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Sample records for network inhibition radiosensitizes

  1. Clonal cell populations unresponsive to radiosensitization induced by telomerase inhibition

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    Ju, Yeun-Jin; Shin, Hyun-Jin; Park, Jeong-Eun; Juhn, Kyoung-Mi; Woo, Seon Rang; Kim, Hee-Young; Han, Young-Hoon; Hwang, Sang-Gu; Hong, Sung-Hee; Kang, Chang-Mo; Yoo, Young-Do; Park, Won-Bong; Cho, Myung-Haing; Park, Gil Hong; Lee, Kee-Ho

    2010-01-01

    Research highlights: → In our present manuscript, we have clearly showed an interesting but problematic obstacle of a radiosensitization strategy based on telomerase inhibition by showing that: Clonal population unresponsive to this radiosensitization occasionally arise. → The telomere length of unsensitized clones was reduced, as was that of most sensitized clones. → The unsensitized clones did not show chromosome end fusion which was noted in all sensitized clones. → P53 status is not associated with the occurrence of unsensitized clone. → Telomere end capping in unsensitized clone is operative even under telomerase deficiency. -- Abstract: A combination of a radiotherapeutic regimen with telomerase inhibition is valuable when tumor cells are to be sensitized to radiation. Here, we describe cell clones unresponsive to radiosensitization after telomere shortening. After extensive division of individual transformed clones of mTERC -/- cells, about 22% of clones were unresponsive to radiosensitization even though telomerase action was inhibited. The telomere lengths of unsensitized mTERC -/- clones were reduced, as were those of most sensitized clones. However, the unsensitized clones did not exhibit chromosomal end-to-end fusion to the extent noted in all sensitized clones. Thus, a defense mechanism preventing telomere erosion is operative even when telomeres become shorter under conditions of telomerase deficiency, and results in unresponsiveness to the radiosensitization generally mediated by telomere shortening.

  2. Inhibiting DNA-PKCS radiosensitizes human osteosarcoma cells

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    Mamo, Tewodros; Mladek, Ann C.; Shogren, Kris L.; Gustafson, Carl; Gupta, Shiv K.; Riester, Scott M.; Maran, Avudaiappan; Galindo, Mario; Wijnen, Andre J. van; Sarkaria, Jann N.; Yaszemski, Michael J.

    2017-01-01

    Osteosarcoma survival rate has not improved over the past three decades, and the debilitating side effects of the surgical treatment suggest the need for alternative local control approaches. Radiotherapy is largely ineffective in osteosarcoma, indicating a potential role for radiosensitizers. Blocking DNA repair, particularly by inhibiting the catalytic subunit of DNA-dependent protein kinase (DNA-PK CS ), is an attractive option for the radiosensitization of osteosarcoma. In this study, the expression of DNA-PK CS in osteosarcoma tissue specimens and cell lines was examined. Moreover, the small molecule DNA-PK CS inhibitor, KU60648, was investigated as a radiosensitizing strategy for osteosarcoma cells in vitro. DNA-PK CS was consistently expressed in the osteosarcoma tissue specimens and cell lines studied. Additionally, KU60648 effectively sensitized two of those osteosarcoma cell lines (143B cells by 1.5-fold and U2OS cells by 2.5-fold). KU60648 co-treatment also altered cell cycle distribution and enhanced DNA damage. Cell accumulation at the G2/M transition point increased by 55% and 45%, while the percentage of cells with >20 γH2AX foci were enhanced by 59% and 107% for 143B and U2OS cells, respectively. These results indicate that the DNA-PK CS inhibitor, KU60648, is a promising radiosensitizing agent for osteosarcoma. - Highlights: • DNA-PKcs is consistently expressed in human osteosarcoma tissue and cell lines. • The DNA-PKcs inhibitor, KU60648, effectively radiosensitizes osteosarcoma cells. • Combining KU60648 with radiation increases G2/M accumulation and DNA damage.

  3. Phytochemicals radiosensitize cancer cells by inhibiting DNA repair

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    Singh, Rana P.

    2017-01-01

    Solid tumors are mostly treated with radiotherapy. Radiotherapy is toxic to normal tissues and also promote the invasiveness and radioresistance in cancer cells. The resistance against radiotherapy and adverse effects to normal cells reduce the overall therapeutic effects of the treatment. Radiosensitizing agents usually show limited success during clinical trials. Therefore, the search and development of new radiosensitizers showing selective response to only cancer cells is desirable. We analyzed the radiosensitizing effects including cell death effect of silibinin, a phytochemical on prostate cancer cells. Silibinin enhanced gamma radiation (2.5-10 Gy) induced inhibition in colony formation selectively in prostate cancer cells. In cell cycle progression, G2/M phase is the most sensitive phase for radiation-induced damage which was delayed by the compound treatment in radiation exposed cells. The lower concentrations of silibinin substantially enhanced radiation-induced apoptosis. A prolonged reactive oxygen species production was also observed in these treatments EGFR signaling pathway can contribute to radiation-induced pro-survival mechanisms and to the therapeutic resistance. Agent treatment reduced the IR-induced EGFR phosphorylation and consequently reversed the resistance mediating mechanisms within the cancer cell. Thus, inhibiting DNA repair in cancer cells would enhance therapeutic response of radiation in cancer cells. Silibinin affected the localization of EGFR and DNA-dependent protein kinase, the DNA-PK is known to be an important mediator of DSB repair in human cells, and showed increased number of pH2AX (ser139) foci, and thus indicating lower DNA repair in these cancer cells. This was also confirmed in the tumor xenograft study. Our findings suggest that a combination of silibinin with radiation could be an effective treatment of radioresistant human prostate cancer and warrants further investigation. (author)

  4. Radiosensitization by histone deacetylase inhibition in an osteosarcoma mouse model

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    Blattmann, C.; University Children's Hospital of Heidelberg; Thiemann, M.; Stenzinger, A.

    2013-01-01

    Background: Osteosarcomas (OS) are highly malignant and radioresistant tumors. Histone deacetylase inhibitors (HDACi) constitute a novel class of anticancer agents. We sought to investigate the effect of combined treatment with suberoylanilide hydroxamic acid (SAHA) and radiotherapy in OS in vivo. Methods: Clonogenic survival of human OS cell lines as well as tumor growth delay of OS xenografts were tested after treatment with either vehicle, radiotherapy (XRT), SAHA, or XRT and SAHA. Tumor proliferation, necrosis, microvascular density, apoptosis, and p53/p21 were monitored by immunohistochemistry. The CD95 pathway was performed by flow cytometry, caspase (3/7/8) activity measurements, and functional inhibition of CD95 death signaling. Results: Combined treatment with SAHA and XRT markedly reduced the surviving fraction of OS cells as compared to XRT alone. Likewise, dual therapy significantly inhibited OS tumor growth in vivo as compared to XRT alone, reflected by reduced tumor proliferation, impaired angiogenesis, and increased apoptosis. Addition of HDACi to XRT led to elevated p53, p21, CD95, and CD95L expression. Inhibition of CD95 signaling reduced HDACi- and XRT-induced apoptosis. Conclusion: Our data show that HDACi increases the radiosensitivity of osteosarcoma cells at least in part via ligand-induced apoptosis. HDACi thus emerge as potentially useful treatment components of OS. (orig.)

  5. Radiosensitization by histone deacetylase inhibition in an osteosarcoma mouse model

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    Blattmann, C. [Olgahospital, Stuttgart (Germany). Paediatrie 5; University Children' s Hospital of Heidelberg (Germany). Dept. of Pediatric Oncology, Hematology and Immunology; Thiemann, M. [German Cancer Research Center (DKFZ), Heidelberg (Germany). Dept. of Radiotherapy, Molecular- and Translational Radiation Oncology; Stenzinger, A. [Heidelberg Univ. (Germany). Inst. of Pathology; and others

    2013-11-15

    Background: Osteosarcomas (OS) are highly malignant and radioresistant tumors. Histone deacetylase inhibitors (HDACi) constitute a novel class of anticancer agents. We sought to investigate the effect of combined treatment with suberoylanilide hydroxamic acid (SAHA) and radiotherapy in OS in vivo. Methods: Clonogenic survival of human OS cell lines as well as tumor growth delay of OS xenografts were tested after treatment with either vehicle, radiotherapy (XRT), SAHA, or XRT and SAHA. Tumor proliferation, necrosis, microvascular density, apoptosis, and p53/p21 were monitored by immunohistochemistry. The CD95 pathway was performed by flow cytometry, caspase (3/7/8) activity measurements, and functional inhibition of CD95 death signaling. Results: Combined treatment with SAHA and XRT markedly reduced the surviving fraction of OS cells as compared to XRT alone. Likewise, dual therapy significantly inhibited OS tumor growth in vivo as compared to XRT alone, reflected by reduced tumor proliferation, impaired angiogenesis, and increased apoptosis. Addition of HDACi to XRT led to elevated p53, p21, CD95, and CD95L expression. Inhibition of CD95 signaling reduced HDACi- and XRT-induced apoptosis. Conclusion: Our data show that HDACi increases the radiosensitivity of osteosarcoma cells at least in part via ligand-induced apoptosis. HDACi thus emerge as potentially useful treatment components of OS. (orig.)

  6. Radiosensitization of colorectal carcinoma cell lines by histone deacetylase inhibition

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    Flatmark, Kjersti; Nome, Ragnhild V; Folkvord, Sigurd; Bratland, Åse; Rasmussen, Heidi; Ellefsen, Mali Strand; Fodstad, Øystein; Ree, Anne Hansen

    2006-01-01

    The tumor response to preoperative radiotherapy of locally advanced rectal cancer varies greatly, warranting the use of experimental models to assay the efficacy of molecular targeting agents in rectal cancer radiosensitization. Histone deacetylase (HDAC) inhibitors, agents that cause hyperacetylation of histone proteins and thereby remodeling of chromatin structure, may override cell cycle checkpoint responses to DNA damage and amplify radiation-induced tumor cell death. Human colorectal carcinoma cell lines were exposed to ionizing radiation and HDAC inhibitors, and cell cycle profiles and regulatory factors, as well as clonogenicity, were analyzed. In addition to G 2 /M phase arrest following irradiation, the cell lines displayed cell cycle responses typical for either intact or defective p53 function (the presence or absence, respectively, of radiation-induced expression of the cell cycle inhibitor p21 and subsequent accumulation of G 1 phase cells). In contrast, histone acetylation was associated with complete depletion of the G 1 population of cells with functional p53 but accumulation of both G 1 and G 2 /M populations of cells with defective p53. The cellular phenotypes upon HDAC inhibition were consistent with the observed repression of Polo-like kinase-1, a regulatory G 2 /M phase kinase. Following pre-treatment with HDAC inhibitors currently undergoing clinical investigation, the inhibitory effect of ionizing radiation on clonogenicity was significantly amplified. In these experimental models, HDAC inhibition sensitized the tumor cells to ionizing radiation, which is in accordance with the concept of increased probability of tumor cell death when chromatin structure is modified

  7. Hedgehog Pathway Inhibition Radiosensitizes Non-Small Cell Lung Cancers

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    Zeng, Jing; Aziz, Khaled; Chettiar, Sivarajan T. [Department of Radiation Oncology and Molecular Radiation Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Aftab, Blake T. [Department of Medical Oncology, The Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Armour, Michael; Gajula, Rajendra; Gandhi, Nishant; Salih, Tarek; Herman, Joseph M.; Wong, John [Department of Radiation Oncology and Molecular Radiation Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Rudin, Charles M. [Department of Medical Oncology, The Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Tran, Phuoc T. [Department of Radiation Oncology and Molecular Radiation Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Department of Medical Oncology, The Johns Hopkins University School of Medicine, Baltimore, Maryland (United States); Hales, Russell K., E-mail: rhales1@jhmi.edu [Department of Radiation Oncology and Molecular Radiation Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland (United States)

    2013-05-01

    Purpose: Despite improvements in chemoradiation, local control remains a major clinical problem in locally advanced non-small cell lung cancer. The Hedgehog pathway has been implicated in tumor recurrence by promoting survival of tumorigenic precursors and through effects on tumor-associated stroma. Whether Hedgehog inhibition can affect radiation efficacy in vivo has not been reported. Methods and Materials: We evaluated the effects of a targeted Hedgehog inhibitor (HhAntag) and radiation on clonogenic survival of human non-small cell lung cancer lines in vitro. Using an A549 cell line xenograft model, we examined tumor growth, proliferation, apoptosis, and gene expression changes after concomitant HhAntag and radiation. In a transgenic mouse model of Kras{sup G12D}-induced and Twist1-induced lung adenocarcinoma, we assessed tumor response to radiation and HhAntag by serial micro-computed tomography (CT) scanning. Results: In 4 human lung cancer lines in vitro, HhAntag showed little or no effect on radiosensitivity. By contrast, in both the human tumor xenograft and murine inducible transgenic models, HhAntag enhanced radiation efficacy and delayed tumor growth. By use of the human xenograft model to differentiate tumor and stromal effects, mouse stromal cells, but not human tumor cells, showed significant and consistent downregulation of Hedgehog pathway gene expression. This was associated with increased tumor cell apoptosis. Conclusions: Targeted Hedgehog pathway inhibition can increase in vivo radiation efficacy in lung cancer preclinical models. This effect is associated with pathway suppression in tumor-associated stroma. These data support clinical testing of Hedgehog inhibitors as a component of multimodality therapy for locally advanced non-small cell lung cancer.

  8. Radiosensitive Down syndrome lymphoblastoid lines have normal ionizing-radiation-induced inhibition of DNA synthesis

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    Ganges, M.B.; Robbins, J.H.; Jiang, H.; Hauser, C.; Tarone, R.E.

    1988-01-01

    The extent of X-ray-induced inhibition of DNA synthesis was determined in radiosensitive lymphoblastoid lines from 3 patients with Down syndrome and 3 patients with ataxia telangiectasia (AT). Compared to 6 normal control lines, the 3 AT lines were abnormally resistant to X-ray-induced inhibition of DNA synthesis, while the 3 Down syndrome lines had normal inhibition. These results demonstrate that radiosensitive human cells can have normal X-ray-induced inhibition of DNA synthesis and provide new evidence for the dissociation of radioresistant DNA synthesis. (author). 27 refs.; 1 fig.; 1 tab

  9. Apoptosis and radiosensitization of Hodgkin cells by proteasome inhibition

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    Pajonk, Frank; Pajonk, Katja; McBride, William H.

    2000-01-01

    Purpose: Malignant cells from Hodgkin's disease have been reported to be defective in regulation of NF-κB activity. Ionizing radiation is known to activate NF-κB, and it has been suggested that this pathway may protect cells from apoptosis following exposure to radiation and other therapeutic agents. Defective NF-κB regulation in Hodgkin cells could therefore dictate the response of this disease to therapy, as well as be responsible for maintaining the malignant phenotype. The purpose of this study was to explore whether NF-κB activity could be modulated in Hodgkin cells and whether it determines the response of these cells to treatment with ionizing radiation and/or dexamethasone. Methods and Materials: Activation of NF-κB in cells is accomplished in large part by degradation of its inhibitor IκB through the 26s proteasome. HD-My-Z Hodgkin cells were treated with the proteasome inhibitor MG-132 or transduced with a dominant negative super-repressor IκBα. Clonogenic survival, apoptosis, proteasome activity, and NF-κB binding activity were monitored in response to ionizing radiation and/or dexamethasone treatment. Results: HD-My-Z Hodgkin cells had modest NF-κB levels but, unlike other cell types, did not decrease their level of constitutively active NF-κB in response to proteasome inhibition with MG-132. In contrast, transduction with a non-phosphorable IκBα construct abolished expression. MG-132 did, however, induce apoptosis in HD-My-Z cells and sensitized them to ionizing radiation. Dexamethasone treatment had no effect on NF-κB activity or clonogenic survival of Hodgkin cells, but protected them from irradiation. Conclusion: We conclude that inhibition of 26s proteasome activity can induce apoptosis in HD-My-Z Hodgkin cells and radiosensitize them, in spite of the fact that their constitutively active NF-κB levels are unaltered. The proteasome may be a promising new therapeutic target for intervention in this disease. In contrast, the use of

  10. The inhibition of PARP but not EGFR results in the radiosensitization of HPV/p16-positive HNSCC cell lines

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    Güster, Julian David; Weissleder, Stephanie Valerie; Busch, Chia-Jung; Kriegs, Malte; Petersen, Cordula; Knecht, Rainald; Dikomey, Ekkehard; Rieckmann, Thorsten

    2014-01-01

    Background and purpose: HPV-negative and HPV-positive HNSCC comprise distinct tumor entities with different biological characteristics. Specific regimens for the comparably well curable HPV-positive entity that reduce side effects without compromising outcome have yet to be established. Therefore, we tested here whether the inhibition of EGFR or PARP may be used to specifically enhance the radiosensitivity of HPV-positive HNSCC cells. Materials and methods: Experiments were performed with five HPV/p16-positive HNSCC cell lines. Inhibitors used were cetuximab, olaparib and PF-00477736. The respective inhibition of EGFR, PARP and Chk1 was evaluated by Western blot, immunofluorescence analysis and assessment of cell cycle distribution. Cell survival was assessed by colony formation assay. Results: Inhibition of EGFR by cetuximab failed to radiosensitize any of the HPV-positive HNSCC cell lines tested. In contrast, PARP-inhibition resulted in a substantial radiosensitization of all strains, with the sensitization being further enhanced by the additional inhibition of Chk1. Conclusions: PARP-inhibition effectively radiosensitizes HPV-positive HNSCC cells and may therefore represent a viable alternative to chemotherapy possibly even allowing for a reduction in radiation dose. For the latter, PARP-inhibition may be combined with the inhibition of Chk1. In contrast, the inhibition of EGFR cannot be expected to radiosensitize HPV-positive HNSCC through the modulation of cellular radiosensitivity

  11. Garcinol, a Histone Acetyltransferase Inhibitor, Radiosensitizes Cancer Cells by Inhibiting Non-Homologous End Joining

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    Oike, Takahiro [Division of Multistep Carcinogenesis, National Cancer Center Research Institute, Chuo-ku, Tokyo (Japan); Division of Genome Biology, National Cancer Center Research Institute, Chuo-ku, Tokyo (Japan); Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Gunma (Japan); Ogiwara, Hideaki [Division of Genome Biology, National Cancer Center Research Institute, Chuo-ku, Tokyo (Japan); Torikai, Kohta [Gunma University Heavy Ion Medical Center, Maebashi, Gunma (Japan); Nakano, Takashi [Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Gunma (Japan); Yokota, Jun [Division of Multistep Carcinogenesis, National Cancer Center Research Institute, Chuo-ku, Tokyo (Japan); Kohno, Takashi, E-mail: tkkohno@ncc.go.jp [Division of Genome Biology, National Cancer Center Research Institute, Chuo-ku, Tokyo (Japan)

    2012-11-01

    Purpose: Non-homologous end joining (NHEJ), a major pathway used to repair DNA double-strand breaks (DSBs) generated by ionizing radiation (IR), requires chromatin remodeling at DSB sites through the acetylation of histones by histone acetyltransferases (HATs). However, the effect of compounds with HAT inhibitory activities on the DNA damage response (DDR), including the NHEJ and cell cycle checkpoint, as well as on the radiosensitivity of cancer cells, remains largely unclear. Here, we investigated whether garcinol, a HAT inhibitor found in the rinds of Garcinia indica fruit (called mangosteens), has effects on DDR, and whether it can be used for radiosensitization. Methods and Materials: The following assays were used to examine the effect of garcinol on the inhibition of DSB repair, including the following: a conventional neutral comet assay; a cell-based assay recently developed by us, in which NHEJ repair of DSBs on chromosomal DNA was evaluated; the micrococcal nuclease sensitivity assay; and immunoblotting for autophosphorylation of DNA-dependent protein kinase catalytic subunit (DNA-PKcs). We assessed the effect of garcinol on the cell cycle checkpoint after IR treatment by analyzing the phosphorylation levels of checkpoint kinases CHK1 and CHK2 and histone H3, and by cell cycle profile analysis using flow cytometry. The radiosensitizing effect of garcinol was assessed by a clonogenic survival assay, whereas its effects on apoptosis and senescence were examined by annexin V and senescence-associated {beta}-galactosidase (SA-{beta}-Gal) staining, respectively. Results: We found that garcinol inhibits DSB repair, including NHEJ, without affecting cell cycle checkpoint. Garcinol radiosensitized A549 lung and HeLa cervical carcinoma cells with dose enhancement ratios (at 10% surviving fraction) of 1.6 and 1.5, respectively. Cellular senescence induced by IR was enhanced by garcinol. Conclusion: These results suggest that garcinol is a radiosensitizer that

  12. Inhibition of DNA synthesis and radiosensitization effects of thalidomide on esophageal carcinoma TE1 cells

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    Yu Jingping; Sun Suping; Sun Zhiqiang; Sun Meiling; Liu Fenju

    2010-01-01

    Objective: To explore the radiosensitization effect of thalidomide combined with X-ray on esophageal carcinoma TE1 cells. Methods: Cell scratch assay was used to detect the inhibition ability of different concentration of Thalidomide on cell invasion and metastasis. H 3 -TdR incorporation assay was used to investigate the inhibition of DNA synthesis in TE1 cells by treated with Thalidomide singly or combination with X-rays. The colony formation assay was used to analyze the radiosensitization of Thalidomide effect on TE1 cells. Results: Thalidomide had obvious inhibition effect on TE1 cell metastasis, DNA synthesis and colony formation, which were correlated with drug concentration. The values D 0 , D q and SF 2 in TE1 cells were gradually decreased with thalidomide concentration increased. When the concentration of thalidomide was 100μg/ml, the SER D 0 and SER D 0 and SER D q were (1.4±0.2) and (1.5±0.1), respectively, While the concentration of thalidomide was 150 μg/ml, the SER D 0 and SER D q were (1.5±0.2) and (1.8±0.2), respectively. Conclusions: Thalidomide could inhibit TE1 cell invasion, metastasis, DNA synthesis, and significantly enhance the radiosensitizing effect on esophageal carcinoma TE1 cells. (authors)

  13. Radiosensitization In Vivo by Histone Deacetylase Inhibition with No Increase in Early Normal Tissue Radiation Toxicity.

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    Groselj, Blaz; Ruan, Jia-Ling; Scott, Helen; Gorrill, Jessica; Nicholson, Judith; Kelly, Jacqueline; Anbalagan, Selvakumar; Thompson, James; Stratford, Michael R L; Jevons, Sarah J; Hammond, Ester M; Scudamore, Cheryl L; Kerr, Martin; Kiltie, Anne E

    2018-02-01

    As the population ages, more elderly patients require radiotherapy-based treatment for their pelvic malignancies, including muscle-invasive bladder cancer, as they are unfit for major surgery. Therefore, there is an urgent need to find radiosensitizing agents minimally toxic to normal tissues, including bowel and bladder, for such patients. We developed methods to determine normal tissue toxicity severity in intestine and bladder in vivo , using novel radiotherapy techniques on a small animal radiation research platform (SARRP). The effects of panobinostat on in vivo tumor growth delay were evaluated using subcutaneous xenografts in athymic nude mice. Panobinostat concentration levels in xenografts, plasma, and normal tissues were measured in CD1-nude mice. CD1-nude mice were treated with drug/irradiation combinations to assess acute normal tissue effects in small intestine using the intestinal crypt assay, and later effects in small and large intestine at 11 weeks by stool assessment and at 12 weeks by histologic examination. In vitro effects of panobinostat were assessed by qPCR and of panobinostat, TMP195, and mocetinostat by clonogenic assay, and Western blot analysis. Panobinostat resulted in growth delay in RT112 bladder cancer xenografts but did not significantly increase acute (3.75 days) or 12 weeks' normal tissue radiation toxicity. Radiosensitization by panobinostat was effective in hypoxic bladder cancer cells and associated with class I HDAC inhibition, and protein downregulation of HDAC2 and MRE11. Pan-HDAC inhibition is a promising strategy for radiosensitization, but more selective agents may be more useful radiosensitizers clinically, resulting in fewer systemic side effects. Mol Cancer Ther; 17(2); 381-92. ©2017 AACR See all articles in this MCT Focus section, "Developmental Therapeutics in Radiation Oncology." ©2017 American Association for Cancer Research.

  14. SHP1-mediated cell cycle redistribution inhibits radiosensitivity of non-small cell lung cancer

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    Cao, Rubo; Ding, Qian; Li, Pindong; Xue, Jun; Zou, Zhenwei; Huang, Jing; Peng, Gang

    2013-01-01

    Radioresistance is the common cause for radiotherapy failure in non-small cell lung cancer (NSCLC), and the degree of radiosensitivity of tumor cells is different during different cell cycle phases. The objective of the present study was to investigate the effects of cell cycle redistribution in the establishment of radioresistance in NSCLC, as well as the signaling pathway of SH2 containing Tyrosine Phosphatase (SHP1). A NSCLC subtype cell line, radioresistant A549 (A549S1), was induced by high-dose hypofractionated ionizing radiations. Radiosensitivity-related parameters, cell cycle distribution and expression of cell cycle-related proteins and SHP1 were investigated. siRNA was designed to down-regulate SHP1expression. Compared with native A549 cells, the proportion of cells in the S phase was increased, and cells in the G0/G1 phase were consequently decreased, however, the proportion of cells in the G2/M phase did not change in A549S1 cells. Moreover, the expression of SHP1, CDK4 and CylinD1 were significantly increased, while p16 was significantly down-regulated in A549S1 cells compared with native A549 cells. Furthermore, inhibition of SHP1 by siRNA increased the radiosensitivity of A549S1 cells, induced a G0/G1 phase arrest, down-regulated CDK4 and CylinD1expressions, and up-regulated p16 expression. SHP1 decreases the radiosensitivity of NSCLC cells through affecting cell cycle distribution. This finding could unravel the molecular mechanism involved in NSCLC radioresistance

  15. Inhibition of STAT-3 results in radiosensitization of human squamous cell carcinoma

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    Bonner, James A.; Trummell, Hoa Q.; Willey, Christopher D.; Plants, Brian A.; Raisch, Kevin P.

    2009-01-01

    Background: Signal transducer and activator of transcription-3 (STAT-3) is a downstream component of the Epidermal Growth Factor Receptor (EGFr) signaling process that may facilitate the resistance of tumor cells to conventional cancer treatments. Studies were performed to determine if inhibition of this downstream protein produces radiosensitization. Methods/Results: A431 cells (human squamous cell carcinoma cells with EGFr overexpression) were found to be sensitized to radiation after treatment with STAT-3 small interfering RNA (siRNA). Therefore, a short hairpin RNA (shRNA) against STAT-3 was designed and cloned into a pBABE vector system modified for shRNA expression. Following transfection, clone 2.1 was selected for further study as it showed a dramatic reduction of STAT-3 protein (and mRNA) when compared to A431 parental cells or a negative control shRNA cell line (transfected with STAT-3 shRNA with 2 base pairs mutated). A431 2.1 showed doubling times of 25-31 h as compared to 18-24 h for the parental cell line. The A431 shRNA knockdown STAT-3 cells A431 were more sensitive to radiation than A431 parental or negative STAT-3 control cells. Conclusion: A431 cells stably transfected with shRNA against STAT-3 resulted in enhanced radiosensitivity. Further work will be necessary to determine whether the inhibition of STAT-3 phosphorylation is a necessary step for the radiosensitization that is induced by the inhibition of EGFr.

  16. Cisplatin-mediated radiosensitization of non-small cell lung cancer cells is stimulated by ATM inhibition

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    Toulany, Mahmoud; Mihatsch, Julia; Holler, Marina; Chaachouay, Hassan; Rodemann, H. Peter

    2014-01-01

    Background and purpose: Cisplatin activates ataxia-telangiectasia-mutated (ATM), a protein with roles in DNA repair, cell cycle progression and autophagy. We investigated the radiosensitizing effect of cisplatin with respect to its effect on ATM pathway activation. Material and methods: Non-small cell lung cancer cells (NSCLC) cell lines (A549, H460) and human fibroblast (ATM-deficient AT5, ATM-proficient 1BR3) cells were used. The effects of cisplatin combined with irradiation on ATM pathway activity, clonogenicity, DNA double-strand break (DNA-DSB) repair and cell cycle progression were analyzed with Western blotting, colony formation and γ-H2AX foci assays as well as FACS analysis, respectively. Results: Cisplatin radiosensitized H460 cells, but not A549 cells. Radiosensitization of H460 cells was not due to impaired DNA-DSB repair, increased apoptosis or cell cycle dysregulation. The lack of radiosensitization demonstrated for A549 cells was associated with cisplatin-mediated stimulation of ATM (S1981) and AMPKα (T172) phosphorylation and autophagy. However, in both cell lines inhibition of ATM and autophagy by KU-55933 and chloroquine diphosphate (CQ) respectively resulted in a significant radiosensitization. Combined treatment with the AMPK inhibitor compound-C led to radiosensitization of A549 but not of H460 cells. As compared to the treatment with KU-55933 alone, radiosensitivity of A549 cells was markedly stimulated by the combination of KU-55933 and cisplatin. However, the combination of CQ and cisplatin did not modulate the pattern of radiation sensitivity of A549 or H460 cells. In accordance with the results that cisplatin via stimulation of ATM activity can abrogate its radiosensitizing effect, ATM deficient cells were significantly sensitized to ionizing radiation by cisplatin. Conclusion: The results obtained indicate that ATM targeting can potentiate cisplatin-induced radiosensitization

  17. Autotaxin inhibition with PF8380 enhances the radiosensitivity of human and murine glioblastoma cell lines

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    Sandeep R Bhave

    2013-09-01

    Full Text Available Purpose: Glioblastoma multiforme (GBM is an aggressive primary brain tumor that is radio-resistant and recurs despite aggressive surgery, chemo and radiotherapy. Autotaxin (ATX is over expressed in various cancers including GBM and is implicated in tumor progression, invasion, and angiogenesis. Using the ATX specific inhibitor, PF-8380, we studied ATX as a potential target to enhance radiosensitivity in GBM.Methods and Materials: Mouse GL-261 and Human U87MG cells were used as GBM cell models. Clonogenic survival assays and tumor transwell invasion assays were performed using PF-8380 to evaluate role of ATX in survival and invasion. Radiation dependent activation of Akt was analyzed by immunoblotting. Tumor induced angiogenesis was studied using the dorsal skin-fold model in Gl-261. Heterotopic mouse GL-261 tumors were used to evaluate the efficacy of PF-8380 as a radiosensitizer.Results: Pretreatment of GL-261 and U87-MG cells with 1µM PF-8380 followed by 4Gy irradiation resulted in decreased clonogenic survival, decreased migration (33% in GL-261;P = 0.002 and 17.9% in U87; P = 0.012 decreased invasion (35.6% in GL-261; P = 0.0037 and 31.8% in U87; P = 0.002, and attenuated radiation induced Akt phosphorylation. In the tumor window model inhibition of ATX abrogated radiation-induced tumor neovascularization (65%; P=0.011. In a heterotopic mouse GL-261 tumors untreated mice took 11.2 days to reach a tumor volume of 7000 mm3 , however combination of PF-8380 (10mg/kg with irradiation (5 fractions of 2Gy took more than 32 days to reach a tumor volume of 7000 mm3 .Conclusion: Inhibition of ATX by PF8380 led to decreased invasion and enhanced radiosensitization of glioma cells. Radiation induced activation of Akt was abrogated by inhibition of ATX. Furthermore, inhibition of ATX led to diminished tumor vascularity and delayed tumor growth. These results suggest that inhibition of ATX may ameliorate glioblastoma response to radiotherapy.

  18. Targeted Radiosensitization of ETS Fusion-Positive Prostate Cancer through PARP1 Inhibition

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    Sumin Han

    2013-10-01

    Full Text Available ETS gene fusions, which result in overexpression of an ETS transcription factor, are considered driving mutations in approximately half of all prostate cancers. Dysregulation of ETS transcription factors is also known to exist in Ewing's sarcoma, breast cancer, and acute lymphoblastic leukemia. We previously discovered that ERG, the predominant ETS family member in prostate cancer, interacts with the DNA damage response protein poly (ADP-ribose polymerase 1 (PARP1 in human prostate cancer specimens. Therefore, we hypothesized that the ERG-PARP1 interaction may confer radiation resistance by increasing DNA repair efficiency and that this radio-resistance could be reversed through PARP1 inhibition. Using lentiviral approaches, we established isogenic models of ERG overexpression in PC3 and DU145 prostate cancer cell lines. In both cell lines, ERG overexpression increased clonogenic survival following radiation by 1.25 (±0.07 fold (mean ± SEM and also resulted in increased PARP1 activity. PARP1 inhibition with olaparib preferentially radiosensitized ERG-positive cells by a factor of 1.52 (±0.03 relative to ERG-negative cells (P < .05. Neutral and alkaline COMET assays and immunofluorescence microscopy assessing γ-H2AX foci showed increased short- and long-term efficiencies of DNA repair, respectively, following radiation that was preferentially reversed by PARP1 inhibition. These findings were verified in an in vivo xenograft model. Our findings demonstrate that ERG overexpression confers radiation resistance through increased efficiency of DNA repair following radiation that can be reversed through inhibition of PARP1. These results motivate the use of PARP1 inhibitors as radiosensitizers in patients with localized ETS fusion-positive cancers.

  19. DNA-PK. The major target for wortmannin-mediated radiosensitization by the inhibition of DSB repair via NHEJ pathway

    International Nuclear Information System (INIS)

    Hashimoto, Mitsumasa; Rao, S.; Tokuno, Osamu; Utsumi, Hiroshi; Takeda, Shunichi

    2003-01-01

    The effect of wortmannin posttreatment was studied in cells derived from different species (hamster, mouse, chicken, and human) with normal and defective DNA-dependent protein kinase (DNA-PK) activity, cells with and without the ataxia telangiectasia mutated (ATM) gene, and cells lacking other regulatory proteins involved in the DNA double-strand break (DSB) repair pathways. Clonogenic assays were used to obtain all results. Wortmannin radiosensitization was observed in Chinese hamster cells (V79-B310H, CHO-K1), mouse mammary carcinoma cells (SR-1), transformed human fibroblast (N2KYSV), chicken B lymphocyte wild-type cells (DT40), and chicken Rad54 knockout cells (Rad54 -/- ). However, mouse mammary carcinoma cells (SX9) with defects in the DNA-PK and chicken DNA-PK catalytic subunit (DNA-PKcs) knockout cells (DNA-PKcs -/-/- ) failed to exhibit wortmannin radiosensitization. On the other hand, severe combined immunodeficiency (SCID) mouse cells (SC3VA2) exposed to wortmannin exhibited significant increases in radiosensitivity, possibly because of some residual function of DNA-PKcs. Moreover, the transformed human cells derived from AT patients (AT2KYSV) and chicken ATM knockout cells (ATM -/- ) showed pronounced wortmannin radiosensitization. These studies demonstrate confirm that the mechanism underlying wortmannin radiosensitization is the inhibition of DNA-PK, but not of ATM, thereby resulting in the inhibition of DSB repair via nonhomologous endjoining (NHEJ). (author)

  20. Inhibition of HAS2 induction enhances the radiosensitivity of cancer cells via persistent DNA damage

    International Nuclear Information System (INIS)

    Shen, Yan Nan; Shin, Hyun-Jin; Joo, Hyun-Yoo; Park, Eun-Ran; Kim, Su-Hyeon; Hwang, Sang-Gu; Park, Sang Jun; Kim, Chun-Ho; Lee, Kee-Ho

    2014-01-01

    Highlights: •HAS2 may be a promising target for the radiosensitization of human cancer. •HAS2 is elevated (up to ∼10-fold) in irradiated radioresistant and -sensitive cancer cells. •HAS2 knockdown sensitizes cancer cells to radiation. •HAS2 knockdown potentiates irradiation-induced DNA damage and apoptotic death. •Thus, the irradiation-induced up-regulation of HAS2 contributes to the radioresistance of cancer cells. -- Abstract: Hyaluronan synthase 2 (HAS2), a synthetic enzyme for hyaluronan, regulates various aspects of cancer progression, including migration, invasion and angiogenesis. However, the possible association of HAS2 with the response of cancer cells to anticancer radiotherapy, has not yet been elucidated. Here, we show that HAS2 knockdown potentiates irradiation-induced DNA damage and apoptosis in cancer cells. Upon exposure to radiation, all of the tested human cancer cell lines exhibited marked (up to 10-fold) up-regulation of HAS2 within 24 h. Inhibition of HAS2 induction significantly reduced the survival of irradiated radioresistant and -sensitive cells. Interestingly, HAS2 depletion rendered the cells to sustain irradiation-induced DNA damage, thereby leading to an increase of apoptotic death. These findings indicate that HAS2 knockdown sensitizes cancer cells to radiation via persistent DNA damage, further suggesting that the irradiation-induced up-regulation of HAS2 contributes to the radioresistance of cancer cells. Thus, HAS2 could potentially be targeted for therapeutic interventions aimed at radiosensitizing cancer cells

  1. Allosuppressor T lymphocytes abolish migration inhibition factor production in autoimmune thyroid disease: evidence from radiosensitivity experiments

    International Nuclear Information System (INIS)

    Topliss, D.J.; Okita, N.; Lewis, M.; Row, V.V.; Volpe, R.

    1981-01-01

    The ability of normal T lymphocytes to abolish the production of migration inhibition factor by antigen-sensitized T lymphocytes of Graves' disease (GD) and Hashimoto's thyroiditis (HT) in response to thyroid antigen has been studied by a modified migration inhibition factor test using isolated T lymphocytes alone. The production of migration inhibition factor was consistently abolished when normal T lymphocytes were mixed with GD or HT T lymphocytes in various ratios (1:9, 2:8, 5:5) as reported previously (Okita et al., 1980b). However, prior in-vitro irradiation (1000 rad) of the normal T lymphocytes resulted in loss of their ability to abolish migration inhibition factor production by the antigen-sensitized T lymphocytes of GD and HT. The effect is consistent with the radiosensitivity of suppressor T lymphocytes and indicates that the effect of normal T lymphocytes on GD and HT T lymphocytes is one of allosuppression. The results support the view that there is a defect in suppressor T cell function in GD and HT. (author)

  2. Radiosensitization of NSCLC cells by EGFR inhibition is the result of an enhanced p53-dependent G1 arrest

    International Nuclear Information System (INIS)

    Kriegs, Malte; Gurtner, Kristin; Can, Yildiz; Brammer, Ingo; Rieckmann, Thorsten; Oertel, Reinhard; Wysocki, Marek; Dorniok, Franziska; Gal, Andreas; Grob, Tobias J.; Laban, Simon; Kasten-Pisula, Ulla; Petersen, Cordula; Baumann, Michael; Krause, Mechthild; Dikomey, Ekkehard

    2015-01-01

    Purpose: How EGF receptor (EGFR) inhibition induces cellular radiosensitization and with that increase in tumor control is still a matter of discussion. Since EGFR predominantly regulates cell cycle and proliferation, we studied whether a G1-arrest caused by EGFR inhibition may contribute to these effects. Materials and methods: We analyzed human non-small cell lung cancer (NSCLC) cell lines either wild type (wt) or mutated in p53 (A549, H460, vs. H1299, H3122) and HCT116 cells (p21 wt and negative). EGFR was inhibited by BIBX1382BS, erlotinib or cetuximab; p21 was knocked down by siRNA. Functional endpoints analyzed were cell signaling, proliferation, G1-arrest, cell survival as well as tumor control using an A549 tumor model. Results: When combined with IR, EGFR inhibition enhances the radiation-induced permanent G1 arrest, though solely in cells with intact p53/p21 signaling. This increase in G1-arrest was always associated with enhanced cellular radiosensitivity. Strikingly, this effect was abrogated when cells were re-stimulated, suggesting the initiation of dormancy. In line with this, only a small non-significant increase in tumor control was observed for A549 tumors treated with fractionated RT and EGFR inhibition. Conclusion: For NSCLC cells increase in radiosensitivity by EGFR inhibition results from enhanced G1-arrest. However, this effect does not lead to improved tumor control because cells can be released from this arrest by re-stimulation

  3. Radiosensitization in esophageal squamous cell carcinoma. Effect of polo-like kinase 1 inhibition

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jenny Ling-Yu [National Taiwan University, Institute of Biomedical Engineering, College of Medicine and College of Engineering, Taipei (China); National Taiwan University Hospital Hsin-Chu Branch, Department of Radiation Oncology, Hsin-Chu (China); National Taiwan University Hospital and National Taiwan University Cancer Center, Department of Oncology, Taipei (China); Chen, Jo-Pai [National Taiwan University Hospital and National Taiwan University Cancer Center, Department of Oncology, Taipei (China); National Taiwan University Hospital Yun-Lin Branch, Department of Oncology, Yun-Lin (China); Huang, Yu-Sen [National Taiwan University, Institute of Biomedical Engineering, College of Medicine and College of Engineering, Taipei (China); National Taiwan University Hospital, Department of Medical Imaging, Taipei (China); National Taiwan University Hospital Yun-Lin Branch, Department of Medical Imaging, Yun-Lin (China); Tsai, Yuan-Chun; Tsai, Ming-Hsien; Jaw, Fu-Shan [National Taiwan University, Institute of Biomedical Engineering, College of Medicine and College of Engineering, Taipei (China); Cheng, Jason Chia-Hsien; Kuo, Sung-Hsin [National Taiwan University Hospital and National Taiwan University Cancer Center, Department of Oncology, Taipei (China); National Taiwan University, Graduate Institute of Oncology, Taipei (China); Shieh, Ming-Jium [National Taiwan University, Institute of Biomedical Engineering, College of Medicine and College of Engineering, Taipei (China); National Taiwan University Hospital and National Taiwan University Cancer Center, Department of Oncology, Taipei (China)

    2016-04-15

    This study examined the efficacy of polo-like kinase 1 (PLK1) inhibition on radiosensitivity in vitro and in vivo by a pharmacologic approach using the highly potent PLK1 inhibitor volasertib. Human esophageal squamous cell carcinoma (ESCC) cell lines KYSE 70 and KYSE 150 were used to evaluate the synergistic effect of volasertib and irradiation in vitro using cell viability assay, colony formation assay, cell cycle phase analysis, and western blot, and in vivo using ectopic tumor models. Volasertib decreased ESCC cell proliferation in a dose- and time-dependent manner. Combination of volasertib and radiation caused G2/M cell cycle arrest, increased cyclin B levels, and induced apoptosis. Volasertib significantly enhanced radiation-induced death in ESCC cells by a mechanism involving the enhancement of histone H3 phosphorylation and significant cell cycle interruption. The combination of volasertib plus irradiation delayed the growth of ESCC tumor xenografts markedly compared with either treatment modality alone. The in vitro results suggested that targeting PLK1 might be a viable approach to improve the effects of radiation in ESCC. In vivo studies showed that PLK1 inhibition with volasertib during irradiation significantly improved local tumor control when compared to irradiation or drug treatment alone. (orig.) [German] Diese Studie untersucht die Wirksamkeit der Polo-like -Kinase 1-(PLK1-)Inhibition auf die Strahlenempfindlichkeit in vitro und in vivo beim oesophagealen Plattenepithelkarzinom durch eine pharmakologische Herangehensweise mit dem hochwirksamen PLK1-Inhibitor Volasertib. Menschliche Zelllinien des oesophagealen Plattenepithelkarzinoms (ESCC), KYSE 70 und KYSE 150, wurden verwendet, um den synergistischen Effekt von Volasertib und Bestrahlung in vitro zu bewerten. Hierzu wurden Zellviabilitaets- und Koloniebildungsuntersuchungen sowie Zellwachstumsanalysen, Immunblots und ektopische In-vivo-Tumormodelle herangezogen. Volasertib verminderte die ESCC

  4. Radiosensitization in esophageal squamous cell carcinoma. Effect of polo-like kinase 1 inhibition

    International Nuclear Information System (INIS)

    Chen, Jenny Ling-Yu; Chen, Jo-Pai; Huang, Yu-Sen; Tsai, Yuan-Chun; Tsai, Ming-Hsien; Jaw, Fu-Shan; Cheng, Jason Chia-Hsien; Kuo, Sung-Hsin; Shieh, Ming-Jium

    2016-01-01

    This study examined the efficacy of polo-like kinase 1 (PLK1) inhibition on radiosensitivity in vitro and in vivo by a pharmacologic approach using the highly potent PLK1 inhibitor volasertib. Human esophageal squamous cell carcinoma (ESCC) cell lines KYSE 70 and KYSE 150 were used to evaluate the synergistic effect of volasertib and irradiation in vitro using cell viability assay, colony formation assay, cell cycle phase analysis, and western blot, and in vivo using ectopic tumor models. Volasertib decreased ESCC cell proliferation in a dose- and time-dependent manner. Combination of volasertib and radiation caused G2/M cell cycle arrest, increased cyclin B levels, and induced apoptosis. Volasertib significantly enhanced radiation-induced death in ESCC cells by a mechanism involving the enhancement of histone H3 phosphorylation and significant cell cycle interruption. The combination of volasertib plus irradiation delayed the growth of ESCC tumor xenografts markedly compared with either treatment modality alone. The in vitro results suggested that targeting PLK1 might be a viable approach to improve the effects of radiation in ESCC. In vivo studies showed that PLK1 inhibition with volasertib during irradiation significantly improved local tumor control when compared to irradiation or drug treatment alone. (orig.) [de

  5. Growth inhibition and radiosensitization of Celecoxib in nasopharyngeal caricnoma cell line CNE-2

    International Nuclear Information System (INIS)

    Xu Xinhua; Yi Fang; Fu Xiangyang; Zhang Xiaohong; Wang Yanlin; Zhang Changju; Du Jingtao

    2009-01-01

    Objective: To investigate the growth inhibition and radiosensitization of Celecoxib in human nasopharyngeal carcinoma cell line CNE-2. Methods: CNE-2 growth inhibition by Celecoxib was evaluated by MTT method. Apoptosis-related changes in morphology were observed by transmission electron microscopy(TEM). Cell cycle distribution and apoptosis rate were measured by flowcytometry(FCM). The expression of COX-2 protein was observed by SP method after the treatment of Celecoxib. Cells were randomly planted into four groups: irradiation control (Ci), drug group (Cd), irradiation group (R), and Celecoxib plus irradiation group (D + R). Single irradiation of 2,4,6,8, and 10 Gy were administered for colonogenic assay. Cell cycle distribution and apoptosis rate were analyzed at 6 Gy irradiation. Results: The growth of CNE-2 cell was inhibited by celecoxib in a dose-and time-dependent manner, the IC 50 was 80 μmol/L. After the treatment, cell ratio of G 0 and G 1 phases wasinereased (47.03 ± 2.76 vs 56.17 ± 1.95, t=4.68, P=0.010), whereas the ratio of S and G 2 /M phases was decreased (33.07 ± 1.86 vs 24.87 ± 1.76, t=5.54,P =0.010;19.30 ± 0.53:17.73 ± 0.83, t=2.75, P=0.050), and the apoptosis rate was increased (1.57 ± 0.47:10.47 ± 0.31,t=27.39, P=0.000) in a dose-dependent manner. Apoptosis with nuclear chromatin condensation, fragmentation and cell shrinkage was found by TEM. SP method showed that Celeib decreased COX-2 expression (17.48 ± 0.34 vs 12.82 ± 0.51, t=13.20, P=0.00). The sensitivity ratio (D 0 ) was 1.15. FCM showed that the percentage of cells in G 2 /M phase was significanty more in R and D + R groups than in Ci and Cd groups (68.00 ± 1.65, 54.27 ± 5.74,17.60 ± 0.80,14.86 ± 1.23, t=47.70,P=0.000; t=11.63, P=0.000), and also significantly different between R group and D + R group (t=3.99, P= 0.020). The apoptosis rate was higher in R and D + R groups than Ci and Cd groups(4.83 ± 0.97,9.50 ± 1.35,1.33 ± 0.86 and 2.28 ± 0.42, t=4.67, P=0.010; t

  6. Pharmacological Inhibition of the Protein Kinase MRK/ZAK Radiosensitizes Medulloblastoma.

    Science.gov (United States)

    Markowitz, Daniel; Powell, Caitlin; Tran, Nhan L; Berens, Michael E; Ryken, Timothy C; Vanan, Magimairajan; Rosen, Lisa; He, Mingzu; Sun, Shan; Symons, Marc; Al-Abed, Yousef; Ruggieri, Rosamaria

    2016-08-01

    Medulloblastoma is a cerebellar tumor and the most common pediatric brain malignancy. Radiotherapy is part of the standard care for this tumor, but its effectiveness is accompanied by significant neurocognitive sequelae due to the deleterious effects of radiation on the developing brain. We have previously shown that the protein kinase MRK/ZAK protects tumor cells from radiation-induced cell death by regulating cell-cycle arrest after ionizing radiation. Here, we show that siRNA-mediated MRK depletion sensitizes medulloblastoma primary cells to radiation. We have, therefore, designed and tested a specific small molecule inhibitor of MRK, M443, which binds to MRK in an irreversible fashion and inhibits its activity. We found that M443 strongly radiosensitizes UW228 medulloblastoma cells as well as UI226 patient-derived primary cells, whereas it does not affect the response to radiation of normal brain cells. M443 also inhibits radiation-induced activation of both p38 and Chk2, two proteins that act downstream of MRK and are involved in DNA damage-induced cell-cycle arrest. Importantly, in an animal model of medulloblastoma that employs orthotopic implantation of primary patient-derived UI226 cells in nude mice, M443 in combination with radiation achieved a synergistic increase in survival. We hypothesize that combining radiotherapy with M443 will allow us to lower the radiation dose while maintaining therapeutic efficacy, thereby minimizing radiation-induced side effects. Mol Cancer Ther; 15(8); 1799-808. ©2016 AACR. ©2016 American Association for Cancer Research.

  7. Metformin enhances radiosensitivity via inhibition of DNA repair pathway in colorectal cancer

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Youn Kyoung; Kim, Mi Sook; Lee, Ji Young; Song, Kyung Hee; Choi, Kyul; Kim, Eun Ho; Ha, Hun Joo [Ewha Womans University, Seoul (Korea, Republic of)

    2014-04-15

    In this study, we provide a scientific rationale for the clinical application of metformin as a radiosensitizer in colorectal cancer. Colorectal cancer (CRC) is the third most common cancer in men and the second most common cancer in women worldwide. Currently, it is one of the commonest chemoradiotherapy worked better than the radiotherapy or chemotherapy in colorectal cancer. To enhance radiosensitivity of tumor cells for chemoradiotherapy, it is to use potential anticancer agents that act as radiosensitizers. Metformin, one of the most widely used antidiabetic drugs, has recently been associated with potential antitumorigenic effects. Our data shows that metformin combined with radiation enhances the efficacy of radiotherapy and down-regulates DNA repair proteins. Therefore, we provides a scientific rationale for the clinical application of metformin as a radiosensitizer in colorectal cancer.

  8. Metformin enhances radiosensitivity via inhibition of DNA repair pathway in colorectal cancer

    International Nuclear Information System (INIS)

    Jeong, Youn Kyoung; Kim, Mi Sook; Lee, Ji Young; Song, Kyung Hee; Choi, Kyul; Kim, Eun Ho; Ha, Hun Joo

    2014-01-01

    In this study, we provide a scientific rationale for the clinical application of metformin as a radiosensitizer in colorectal cancer. Colorectal cancer (CRC) is the third most common cancer in men and the second most common cancer in women worldwide. Currently, it is one of the commonest chemoradiotherapy worked better than the radiotherapy or chemotherapy in colorectal cancer. To enhance radiosensitivity of tumor cells for chemoradiotherapy, it is to use potential anticancer agents that act as radiosensitizers. Metformin, one of the most widely used antidiabetic drugs, has recently been associated with potential antitumorigenic effects. Our data shows that metformin combined with radiation enhances the efficacy of radiotherapy and down-regulates DNA repair proteins. Therefore, we provides a scientific rationale for the clinical application of metformin as a radiosensitizer in colorectal cancer

  9. Icotinib enhances lung cancer cell radiosensitivity in vitro and in vivo by inhibiting MAPK/ERK and AKT activation.

    Science.gov (United States)

    Fu, Yonghong; Zhang, Sen; Wang, Dongjie; Wang, Jing

    2018-05-16

    Icotinib hydrochloride is a small epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) that was developed by Chinese scientists. While clinical trials have revealed its efficacy in the treatment of lung cancer, very little is known about its role in enhancing radiosensitivity. In this study, we investigated the effectiveness of Icotinib in enhancing lung cancer cell radiosensitivity and have detailed its underlying molecular mechanism. The lung cancer cell line H1650 was pretreated with or without Icotinib for 24 hours before radiation, and clonogenic survival assay was performed. Cell apoptosis was also analyzed by flow cytometry, while western blotting was performed to examine the activation of EGFR and its downstream kinases in H1650 cells after Icotinib and radiation treatment. Furthermore, a xenograft animal model was established to evaluate the radiosensitivity of Icotinib in vivo and to confirm its mechanism. Our results demonstrate that pretreatment with Icotinib reduced clonogenic survival after radiation, inhibited EGFR activation, and increased radiation-induced apoptosis in H1650 cells. The phosphorylation of protein kinase B (AKT), extracellular regulated protein kinase 1/2 (ERK1/2), and EGFR was inhibited after Icotinib and radiation combination treatment in vitro and in vivo compared with individual treatments. Combination treatment also affected the expression of the DNA repair protein H2A histone family member X (γ-H2AX). In conclusion, our results reveal that Icotinib enhances radiosensitivity in lung cancers in vitro and in vivo and the mechanism of this may involve blocking the EGFR-AKT and MAPK-ERK pathways and limiting DNA repair. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  10. A ruthenium polypyridyl intercalator stalls DNA replication forks, radiosensitizes human cancer cells and is enhanced by Chk1 inhibition

    Science.gov (United States)

    Gill, Martin R.; Harun, Siti Norain; Halder, Swagata; Boghozian, Ramon A.; Ramadan, Kristijan; Ahmad, Haslina; Vallis, Katherine A.

    2016-08-01

    Ruthenium(II) polypyridyl complexes can intercalate DNA with high affinity and prevent cell proliferation; however, the direct impact of ruthenium-based intercalation on cellular DNA replication remains unknown. Here we show the multi-intercalator [Ru(dppz)2(PIP)]2+ (dppz = dipyridophenazine, PIP = 2-(phenyl)imidazo[4,5-f][1,10]phenanthroline) immediately stalls replication fork progression in HeLa human cervical cancer cells. In response to this replication blockade, the DNA damage response (DDR) cell signalling network is activated, with checkpoint kinase 1 (Chk1) activation indicating prolonged replication-associated DNA damage, and cell proliferation is inhibited by G1-S cell-cycle arrest. Co-incubation with a Chk1 inhibitor achieves synergistic apoptosis in cancer cells, with a significant increase in phospho(Ser139) histone H2AX (γ-H2AX) levels and foci indicating increased conversion of stalled replication forks to double-strand breaks (DSBs). Normal human epithelial cells remain unaffected by this concurrent treatment. Furthermore, pre-treatment of HeLa cells with [Ru(dppz)2(PIP)]2+ before external beam ionising radiation results in a supra-additive decrease in cell survival accompanied by increased γ-H2AX expression, indicating the compound functions as a radiosensitizer. Together, these results indicate ruthenium-based intercalation can block replication fork progression and demonstrate how these DNA-binding agents may be combined with DDR inhibitors or ionising radiation to achieve more efficient cancer cell killing.

  11. Radiosensitization by PARP inhibition to proton beam irradiation in cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Hirai, Takahisa [Department of Radiation Oncology, Juntendo University Faculty of Medicine, Bunkyo-ku, Tokyo (Japan); Division of Chemotherapy and Clinical Cancer Research, National Cancer Center Research Institute, Chuo-ku, Tokyo (Japan); Saito, Soichiro; Fujimori, Hiroaki [Division of Chemotherapy and Clinical Cancer Research, National Cancer Center Research Institute, Chuo-ku, Tokyo (Japan); Matsushita, Keiichiro; Nishio, Teiji [Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima-shi, Hiroshima (Japan); Okayasu, Ryuichi [International Open Laboratory, National Institute of Radiological Science, Chiba-shi, Chiba (Japan); Masutani, Mitsuko, E-mail: mmasutan@nagasaki-u.ac.jp [Division of Chemotherapy and Clinical Cancer Research, National Cancer Center Research Institute, Chuo-ku, Tokyo (Japan); Department of Frontier Life Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki (Japan)

    2016-09-09

    The poly(ADP-ribose) polymerase (PARP)-1 regulates DNA damage responses and promotes base excision repair. PARP inhibitors have been shown to enhance the cytotoxicity of ionizing radiation in various cancer cells and animal models. We have demonstrated that the PARP inhibitor (PARPi) AZD2281 is also an effective radiosensitizer for carbon-ion radiation; thus, we speculated that the PARPi could be applied to a wide therapeutic range of linear energy transfer (LET) radiation as a radiosensitizer. Institutes for biological experiments using proton beam are limited worldwide. This study was performed as a cooperative research at heavy ion medical accelerator in Chiba (HIMAC) in National Institute of Radiological Sciences. HIMAC can generate various ion beams; this enabled us to compare the radiosensitization effect of the PARPi on cells subjected to proton and carbon-ion beams from the same beam line. After physical optimization of proton beam irradiation, the radiosensitization effect of the PARPi was assessed in the human lung cancer cell line, A549, and the pancreatic cancer cell line, MIA PaCa-2. The effect of the PARPi, AZD2281, on radiosensitization to Bragg peak was more significant than that to entrance region. The PARPi increased the number of phosphorylated H2AX (γ-H2AX) foci and enhanced G2/M arrest after proton beam irradiation. This result supports our hypothesis that a PARPi could be applied to a wide therapeutic range of LET radiation by blocking the DNA repair response. - Highlights: • Effective radiosensitizers for particle radiation therapy have not been reported. • PARP inhibitor treatment radiosensitized after proton beam irradiation. • The sensitization at Bragg peak was greater than that at entrance region. • DSB induction and G2/M arrest is involved in the sensitization mechanism.

  12. DW-MRI as a Predictive Biomarker of Radiosensitization of GBM through Targeted Inhibition of Checkpoint Kinases.

    Science.gov (United States)

    Williams, Terence M; Galbán, Stefanie; Li, Fei; Heist, Kevin A; Galbán, Craig J; Lawrence, Theodore S; Holland, Eric C; Thomae, Tami L; Chenevert, Thomas L; Rehemtulla, Alnawaz; Ross, Brian D

    2013-04-01

    The inherent treatment resistance of glioblastoma (GBM) can involve multiple mechanisms including checkpoint kinase (Chk1/2)-mediated increased DNA repair capability, which can attenuate the effects of genotoxic chemotherapies and radiation. The goal of this study was to evaluate diffusion-weighted magnetic resonance imaging (DW-MRI) as a biomarker for Chk1/2 inhibitors in combination with radiation for enhancement of treatment efficacy in GBM. We evaluated a specific small molecule inhibitor of Chk1/2, AZD7762, in combination with radiation using in vitro human cell lines and in vivo using a genetically engineered GBM mouse model. DW-MRI and T1-contrast MRI were used to follow treatment effects on intracranial tumor cellularity and growth rates, respectively. AZD7762 inhibited clonal proliferation in a panel of GBM cell lines and increased radiosensitivity in p53-mutated GBM cell lines to a greater extent compared to p53 wild-type cells. In vivo efficacy of AZD7762 demonstrated a dose-dependent inhibitory effect on GBM tumor growth rate and a reduction in tumor cellularity based on DW-MRI scans along with enhancement of radiation efficacy. DW-MRI was found to be a useful imaging biomarker for the detection of radiosensitization through inhibition of checkpoint kinases. Chk1/2 inhibition resulted in antiproliferative activity, prevention of DNA damage-induced repair, and radiosensitization in preclinical GBM tumor models, both in vitro and in vivo. The effects were found to be maximal in p53-mutated GBM cells. These results provide the rationale for integration of DW-MRI in clinical translation of Chk1/2 inhibition with radiation for the treatment of GBM.

  13. Celecoxib Induced Tumor Cell Radiosensitization by Inhibiting Radiation Induced Nuclear EGFR Transport and DNA-Repair: A COX-2 Independent Mechanism

    International Nuclear Information System (INIS)

    Dittmann, Klaus H.; Mayer, Claus; Ohneseit, Petra A.; Raju, Uma; Andratschke, Nickolaus H.; Milas, Luka; Rodemann, H. Peter

    2008-01-01

    Purpose: The purpose of the study was to elucidate the molecular mechanisms mediating radiosensitization of human tumor cells by the selective cyclooxygenase (COX)-2 inhibitor celecoxib. Methods and Materials: Experiments were performed using bronchial carcinoma cells A549, transformed fibroblasts HH4dd, the FaDu head-and-neck tumor cells, the colon carcinoma cells HCT116, and normal fibroblasts HSF7. Effects of celecoxib treatment were assessed by clonogenic cell survival, Western analysis, and quantification of residual DNA damage by γH 2 AX foci assay. Results: Celecoxib treatment resulted in a pronounced radiosensitization of A549, HCT116, and HSF7 cells, whereas FaDu and HH4dd cells were not radiosensitized. The observed radiosensitization could neither be correlated with basal COX-2 expression pattern nor with basal production of prostaglandin E2, but was depended on the ability of celecoxib to inhibit basal and radiation-induced nuclear transport of epidermal growth factor receptor (EGFR). The nuclear EGFR transport was strongly inhibited in A549-, HSF7-, and COX-2-deficient HCT116 cells, which were radiosensitized, but not in FaDu and HH4dd cells, which resisted celecoxib-induced radiosensitization. Celecoxib inhibited radiation-induced DNA-PK activation in A549, HSF7, and HCT116 cells, but not in FaDu and HH4dd cells. Consequentially, celecoxib increased residual γH2AX foci after irradiation, demonstrating that inhibition of DNA repair has occurred in responsive A549, HCT116, and HSF7 cells only. Conclusions: Celecoxib enhanced radiosensitivity by inhibition of EGFR-mediated mechanisms of radioresistance, a signaling that was independent of COX-2 activity. This novel observation may have therapeutic implications such that COX-2 inhibitors may improve therapeutic efficacy of radiation even in patients whose tumor radioresistance is not dependent on COX-2

  14. Inhibition of cyclic AMP response element-directed transcription by decoy oligonucleotides enhances tumor-specific radiosensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Park, Serk In, E-mail: serkin@korea.edu [Department of Biochemistry and Molecular Biology, Korea University College of Medicine, Seoul (Korea, Republic of); The BK21 Plus Program for Biomedical Sciences, Korea University College of Medicine, Seoul (Korea, Republic of); Department of Medicine and Center for Bone Biology, Vanderbilt University School of Medicine, Nashville, TN (United States); Park, Sung-Jun [Department of Biochemistry and Molecular Biology, Korea University College of Medicine, Seoul (Korea, Republic of); Laboratory of Obesity and Aging Research, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD (United States); Lee, Junghan; Kim, Hye Eun; Park, Su Jin; Sohn, Jeong-Won [Department of Biochemistry and Molecular Biology, Korea University College of Medicine, Seoul (Korea, Republic of); Park, Yun Gyu, E-mail: parkyg@korea.ac.kr [Department of Biochemistry and Molecular Biology, Korea University College of Medicine, Seoul (Korea, Republic of)

    2016-01-15

    The radiation stress induces cytotoxic responses of cell death as well as cytoprotective responses of cell survival. Understanding exact cellular mechanism and signal transduction pathways is important in improving cancer radiotherapy. Increasing evidence suggests that cyclic AMP response element binding protein (CREB)/activating transcription factor (ATF) family proteins act as a survival factor and a signaling molecule in response to stress. We postulated that CREB inhibition via CRE decoy oligonucleotide increases tumor cell sensitization to γ-irradiation-induced cytotoxic stress. In the present study, we demonstrate that CREB phosphorylation and CREB DNA-protein complex formation increased in time- and radiation dose-dependent manners, while there was no significant change in total protein level of CREB. In addition, CREB was phosphorylated in response to γ-irradiation through p38 MAPK pathway. Further investigation revealed that CREB blockade by decoy oligonucleotides functionally inhibited transactivation of CREB, and significantly increased radiosensitivity of multiple human cancer cell lines including TP53- and/or RB-mutated cells with minimal effects on normal cells. We also demonstrate that tumor cells ectopically expressing dominant negative mutant CREB (KCREB) and the cells treated with p38 MAPK inhibitors were more sensitive to γ-irradiation than wild type parental cells or control-treated cells. Taken together, we conclude that CREB protects tumor cells from γ-irradiation, and combination of CREB inhibition plus ionizing radiation will be a promising radiotherapeutic approach. - Highlights: • γ-Irradiation induced CREB phosphorylation and CRE-directed transcription in tumor. • γ-Irradiation-induced transcriptional activation of CREB was via p38 MAPK pathway. • CRE blockade increased radiosensitivity of tumor cells but not of normal cells. • CRE decoy oligonucleotides or p38 MAPK inhibitors can be used as radiosensitizers.

  15. Inhibition of cyclic AMP response element-directed transcription by decoy oligonucleotides enhances tumor-specific radiosensitivity

    International Nuclear Information System (INIS)

    Park, Serk In; Park, Sung-Jun; Lee, Junghan; Kim, Hye Eun; Park, Su Jin; Sohn, Jeong-Won; Park, Yun Gyu

    2016-01-01

    The radiation stress induces cytotoxic responses of cell death as well as cytoprotective responses of cell survival. Understanding exact cellular mechanism and signal transduction pathways is important in improving cancer radiotherapy. Increasing evidence suggests that cyclic AMP response element binding protein (CREB)/activating transcription factor (ATF) family proteins act as a survival factor and a signaling molecule in response to stress. We postulated that CREB inhibition via CRE decoy oligonucleotide increases tumor cell sensitization to γ-irradiation-induced cytotoxic stress. In the present study, we demonstrate that CREB phosphorylation and CREB DNA-protein complex formation increased in time- and radiation dose-dependent manners, while there was no significant change in total protein level of CREB. In addition, CREB was phosphorylated in response to γ-irradiation through p38 MAPK pathway. Further investigation revealed that CREB blockade by decoy oligonucleotides functionally inhibited transactivation of CREB, and significantly increased radiosensitivity of multiple human cancer cell lines including TP53- and/or RB-mutated cells with minimal effects on normal cells. We also demonstrate that tumor cells ectopically expressing dominant negative mutant CREB (KCREB) and the cells treated with p38 MAPK inhibitors were more sensitive to γ-irradiation than wild type parental cells or control-treated cells. Taken together, we conclude that CREB protects tumor cells from γ-irradiation, and combination of CREB inhibition plus ionizing radiation will be a promising radiotherapeutic approach. - Highlights: • γ-Irradiation induced CREB phosphorylation and CRE-directed transcription in tumor. • γ-Irradiation-induced transcriptional activation of CREB was via p38 MAPK pathway. • CRE blockade increased radiosensitivity of tumor cells but not of normal cells. • CRE decoy oligonucleotides or p38 MAPK inhibitors can be used as radiosensitizers.

  16. On enhancing drugs effect on radiosensitivity of HeLa cells by inhibiting P13K/Akt signal transduction

    International Nuclear Information System (INIS)

    Xia Shu; Yu Shiying

    2006-01-01

    Objective: To explore the mechanism of PI3K/Akt in radiosensitization of docetaxel and cisplatin by inhibiting PI3K/Akt pathway in HeLa cells. Methods: To detect the 50% inhibition concentration (IC 50 ) of cisplatin and docetaxel in Hela cells by mono-nuclear cell direct cytotoxicity assay (MTT) in vitro. Using the IC 20 of cisplatin and docetaxel in Hela cell or in association with LY294002 for 24 h, then, the cells were irradiated by X-ray with 2,3,4,6,8 Gy. The cell survival fraction was computed by clone formation. Cell survival curve was fitted by multitarget one-hit model, and D q , D 0 , SF 2 , sensitizing enhancing ratio(SER) was calculated. The expression of pAkt and total Akt by western blot were detected. Apoptosis was detected by flow cytometry. Results: 1. Docetaxel and cisplatin improved the phosphorylation of Akt by irradiation obviously. 2. The SER of docetaxel + LY294002 + irradiation group (1.92) was higher than that of docetaxel + irradiation group(1.41). The SER of cisplatin + LY294002 + irradiation group(1.71) was higher than the cisplatin + irradiation group (1.37). 3. Apoptosis rate of docetaxel + LY294002 + irradiation and cisplatin + LY294002 + irradiation groups(12.5%, 10.2%) were higher than those of docetaxel + irradiation and cisplatin + irradiation groups(6.1%, 5.1%). Conclusions: PI3K/Akt signal transduction activation may be as an important reason of radiosensitization reduction of docetaxel and cisplatin in the HeLa cells. Our results show that inhibiting PI3K/Akt can improve the radiosensitization of docetaxel and cisplatin in the HeLa cells. (authors)

  17. Gefitinib Radiosensitizes Stem-Like Glioma Cells: Inhibition of Epidermal Growth Factor Receptor-Akt-DNA-PK Signaling, Accompanied by Inhibition of DNA Double-Strand Break Repair

    International Nuclear Information System (INIS)

    Kang, Khong Bee; Zhu Congju; Wong Yinling; Gao Qiuhan; Ty, Albert; Wong, Meng Cheong

    2012-01-01

    Purpose: We compared radiosensitivity of brain tumor stem cells (BTSCs) with matched nonstem glioma cells, and determined whether gefitinib enhanced BTSC radiosensitivity by inhibiting epidermal growth factor receptor (EGFR)–Akt-DNA–dependent protein kinase (DNA-PK) signaling, followed by enhanced DNA double-stand breaks (DSBs) and inhibition of DSB repair. Methods and Materials: Radiosensitivity of stem-like gliomaspheres and nonstem glioma cells (obtained at patient neurosurgical resection) were evaluated by clonogenic assays, γ-H 2 AX immunostaining and cell cycle distribution. Survival of irradiated and nonirradiated NOD-SCID mice intracranially implanted with stem-like gliomaspheres were monitored. Glioma cells treated with gefitinib, irradiation, or both were assayed for clonogenic survival, γ-H 2 AX immunostaining, DNA-PKcs expression, and phosphorylation of EGFR and Akt. Results: Stem-like gliomaspheres displayed BTSC characteristics of self-renewal; differentiation into lineages of neurons, oligodendrocytes, and astrocytes; and initiation of glioma growth in NOD-SCID mice. Irradiation dose-dependently reduced clonogenic survival, induced G 2 /M arrest and increased γ-H 2 AX immunostaining of nonstem glioma cells, but not stem-like gliomaspheres. There was no difference in survival of irradiated and nonirradiated mice implanted with stem-like gliomaspheres. The addition of gefitinib significantly inhibited clonogenic survival, increased γ-H 2 AX immunostaining, and reduced DNA-PKcs expression of irradiated stem-like gliomaspheres, without affecting irradiated-nonstem glioma cells. Gefitinib alone, and when combined with irradiation, inhibited phosphorylation of EGFR (Y1068 and Y1045) and Akt (S473) in stem-like gliomaspheres. In nonstem glioma cells, gefitinib alone inhibited EGFR Y1068 phosphorylation, with further inhibition by combined gefitinib and irradiation. Conclusions: Stem-like gliomaspheres are resistant to irradiation

  18. Gefitinib radiosensitizes stem-like glioma cells: inhibition of epidermal growth factor receptor-Akt-DNA-PK signaling, accompanied by inhibition of DNA double-strand break repair.

    Science.gov (United States)

    Kang, Khong Bee; Zhu, Congju; Wong, Yin Ling; Gao, Qiuhan; Ty, Albert; Wong, Meng Cheong

    2012-05-01

    We compared radiosensitivity of brain tumor stem cells (BTSCs) with matched nonstem glioma cells, and determined whether gefitinib enhanced BTSC radiosensitivity by inhibiting epidermal growth factor receptor (EGFR)-Akt-DNA-dependent protein kinase (DNA-PK) signaling, followed by enhanced DNA double-stand breaks (DSBs) and inhibition of DSB repair. Radiosensitivity of stem-like gliomaspheres and nonstem glioma cells (obtained at patient neurosurgical resection) were evaluated by clonogenic assays, γ-H(2)AX immunostaining and cell cycle distribution. Survival of irradiated and nonirradiated NOD-SCID mice intracranially implanted with stem-like gliomaspheres were monitored. Glioma cells treated with gefitinib, irradiation, or both were assayed for clonogenic survival, γ-H(2)AX immunostaining, DNA-PKcs expression, and phosphorylation of EGFR and Akt. Stem-like gliomaspheres displayed BTSC characteristics of self-renewal; differentiation into lineages of neurons, oligodendrocytes, and astrocytes; and initiation of glioma growth in NOD-SCID mice. Irradiation dose-dependently reduced clonogenic survival, induced G(2)/M arrest and increased γ-H(2)AX immunostaining of nonstem glioma cells, but not stem-like gliomaspheres. There was no difference in survival of irradiated and nonirradiated mice implanted with stem-like gliomaspheres. The addition of gefitinib significantly inhibited clonogenic survival, increased γ-H(2)AX immunostaining, and reduced DNA-PKcs expression of irradiated stem-like gliomaspheres, without affecting irradiated-nonstem glioma cells. Gefitinib alone, and when combined with irradiation, inhibited phosphorylation of EGFR (Y1068 and Y1045) and Akt (S473) in stem-like gliomaspheres. In nonstem glioma cells, gefitinib alone inhibited EGFR Y1068 phosphorylation, with further inhibition by combined gefitinib and irradiation. Stem-like gliomaspheres are resistant to irradiation-induced cytotoxicity, G(2)/M arrest, and DNA DSBs, compared with nonstem

  19. Gefitinib Radiosensitizes Stem-Like Glioma Cells: Inhibition of Epidermal Growth Factor Receptor-Akt-DNA-PK Signaling, Accompanied by Inhibition of DNA Double-Strand Break Repair

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Khong Bee, E-mail: dmskkb@nccs.com.sg [Brain Tumour Research Laboratory, Division of Medical Sciences, National Cancer Centre Singapore (Singapore); Zhu Congju; Wong Yinling; Gao Qiuhan; Ty, Albert; Wong, Meng Cheong [Brain Tumour Research Laboratory, Division of Medical Sciences, National Cancer Centre Singapore (Singapore)

    2012-05-01

    Purpose: We compared radiosensitivity of brain tumor stem cells (BTSCs) with matched nonstem glioma cells, and determined whether gefitinib enhanced BTSC radiosensitivity by inhibiting epidermal growth factor receptor (EGFR)-Akt-DNA-dependent protein kinase (DNA-PK) signaling, followed by enhanced DNA double-stand breaks (DSBs) and inhibition of DSB repair. Methods and Materials: Radiosensitivity of stem-like gliomaspheres and nonstem glioma cells (obtained at patient neurosurgical resection) were evaluated by clonogenic assays, {gamma}-H{sub 2}AX immunostaining and cell cycle distribution. Survival of irradiated and nonirradiated NOD-SCID mice intracranially implanted with stem-like gliomaspheres were monitored. Glioma cells treated with gefitinib, irradiation, or both were assayed for clonogenic survival, {gamma}-H{sub 2}AX immunostaining, DNA-PKcs expression, and phosphorylation of EGFR and Akt. Results: Stem-like gliomaspheres displayed BTSC characteristics of self-renewal; differentiation into lineages of neurons, oligodendrocytes, and astrocytes; and initiation of glioma growth in NOD-SCID mice. Irradiation dose-dependently reduced clonogenic survival, induced G{sub 2}/M arrest and increased {gamma}-H{sub 2}AX immunostaining of nonstem glioma cells, but not stem-like gliomaspheres. There was no difference in survival of irradiated and nonirradiated mice implanted with stem-like gliomaspheres. The addition of gefitinib significantly inhibited clonogenic survival, increased {gamma}-H{sub 2}AX immunostaining, and reduced DNA-PKcs expression of irradiated stem-like gliomaspheres, without affecting irradiated-nonstem glioma cells. Gefitinib alone, and when combined with irradiation, inhibited phosphorylation of EGFR (Y1068 and Y1045) and Akt (S473) in stem-like gliomaspheres. In nonstem glioma cells, gefitinib alone inhibited EGFR Y1068 phosphorylation, with further inhibition by combined gefitinib and irradiation. Conclusions: Stem-like gliomaspheres are

  20. Melanoma cells show a heterogeneous range of sensitivity to ionizing radiation and are radiosensitized by inhibition of B-RAF with PLX-4032

    International Nuclear Information System (INIS)

    Sambade, Maria J.; Peters, Eldon C.; Thomas, Nancy E.; Kaufmann, William K.; Kimple, Randall J.; Shields, Janiel M.

    2011-01-01

    Purpose: To assess the relative radiosensitivities of a large collection of melanoma cell lines and to determine whether pharmacologic inhibition of mutant B-RAF with PLX-4032 can radiosensitize B-Raf+ melanoma cells. Materials and methods: A large collection of melanoma cell lines (n = 37) were treated with 0-8 Gy IR and clonogenic survival assays used to generate survival curves to rank relative radiosensitivities among the cell lines. The ability of a B-RAF inhibitor, PLX-4032, to radiosensitize highly radioresistant B-Raf+ cells was also assessed by clonogenic cell survival and spheroid invasion assays and the effects of treatment on the cell cycle assessed by FACS. Results: Melanoma cell lines displayed a very large, heterogeneous range of SF2 values (1.002-0.053) with a mean of 0.51. Cell lines with surviving fractions of 0.29 or less at SF2 and SF4 were observed at a high frequency of 18.9% and 70.2%, respectively. Treatment of B-Raf+ cells with the B-RAF inhibitor PLX-4032 in combination with radiation provided enhanced inhibition of both colony formation and invasion, and radiosensitized cells through an increase in G 1 arrest. Conclusions: Our data suggest that melanomas are not uniformly radioresistant with a significant subset displaying inherent radiosensitivity. Pharmacologic inhibition of B-RAF with PLX-4032 effectively radiosensitized B-Raf+ melanoma cells suggesting that this combination approach could provide improved radiotherapeutic response in B-Raf+ melanoma patients.

  1. Effects of HIF-1 inhibition by chetomin on hypoxia-related transcription and radiosensitivity in HT 1080 human fibrosarcoma cells

    International Nuclear Information System (INIS)

    Staab, Adrian; Einsele, Hermann; Flentje, Michael; Vordermark, Dirk; Loeffler, Jürgen; Said, Harun M; Diehlmann, Désirée; Katzer, Astrid; Beyer, Melanie; Fleischer, Markus; Schwab, Franz; Baier, Kurt

    2007-01-01

    Hypoxia-inducible factor-1 (HIF-1) overexpression has been linked to tumor progression and poor prognosis. We investigated whether targeting of HIF-1 using chetomin, a disrupter of the interaction of HIF-1 with the transcriptional coactivator p300, influences the radiosensitivity of hypoxic HT 1080 human fibrosarcoma cells. Optimal dose of chetomin was determined by EGFP-HRE gene reporter assay in stably transfected HT 1080 cells. Cells were assayed for expression of the hypoxia-inducible genes carbonic anhydrase 9 (CA9) and vascular endothelial growth factor (VEGF) by RT-PCR and for clonogenic survival after irradiation with 2, 5 or 10 Gy, under normoxic or hypoxic (0.1% O 2 , 12 h) conditions in the presence or absence of chetomin (150 nM, 12 h, pre-treatment of 4 h). Chetomin treatment significantly reduced CA9 and VEGF mRNA expression in hypoxic cells to 44.4 ± 7.2% and 39.6 ± 16.0%, respectively, of untreated hypoxic controls. Chetomin clearly reduced the modified oxygen enhancement ratio (OER') compared to untreated cells, from 2.02 to 1.27, from 1.86 to 1.22 and from 1.49 to 1.06 at the 50%, 37% and 10% clonogenic survival levels, respectively. HIF-1 inhibition by chetomin effectively reduces hypoxia-dependent transcription and radiosensitizes hypoxic HT 1080 human fibrosarcoma cells in vitro

  2. Co-inhibition of epidermal growth factor receptor and insulin-like growth factor receptor 1 enhances radiosensitivity in human breast cancer cells

    International Nuclear Information System (INIS)

    Li, Ping; Veldwijk, Marlon R; Zhang, Qing; Li, Zhao-bin; Xu, Wen-cai; Fu, Shen

    2013-01-01

    Over-expression of epidermal growth factor receptor (EGFR) or insulin-like growth factor-1 receptor (IGF-1R) have been shown to closely correlate with radioresistance of breast cancer cells. This study aimed to investigate the impact of co-inhibition of EGFR and IGF-1R on the radiosensitivity of two breast cancer cells with different profiles of EGFR and IGF-1R expression. The MCF-7 (EGFR +/−, IGF-1R +++) and MDA-MB-468 (EGFR +++, IGF-1R +++) breast cancer cell lines were used. Radiosensitizing effects were determined by colony formation assay. Apoptosis and cell cycle distribution were measured by flow cytometry. Phospho-Akt and phospho-Erk1/2 were quantified by western blot. In vivo studies were conducted using MDA-MB-468 cells xenografted in nu/nu mice. In MDA-MB-468 cells, the inhibition of IGF-1R upregulated the p-EGFR expression. Either EGFR (AG1478) or IGF-1R inhibitor (AG1024) radiosensitized MDA-MB-468 cells. In MCF-7 cells, radiosensitivity was enhanced by AG1024, but not by AG1478. Synergistical radiosensitizing effect was observed by co-inhibition of EGFR and IGF-1R only in MDA-MB-468 cells with a DMF 10% of 1.90. The co-inhibition plus irradiation significantly induced more apoptosis and arrested the cells at G0/G1 phase in MDA-MB-468 cells. Only co-inhibition of EGFR and IGF-1R synergistically diminished the expression of p-Akt and p-Erk1/2 in MDA-MB-468 cells. In vivo studies further verified the radiosensitizing effects by co-inhibition of both pathways in a MDA-MB-468 xenograft model. Our data suggested that co-inhibition of EGFR and IGF-1R synergistically radiosensitized breast cancer cells with both EGFR and IGF-1R high expression. The approach may have an important therapeutic implication in the treatment of breast cancer patients with high expression of EGFR and IGF-1R

  3. Inhibition of UBE2D3 expression attenuates radiosensitivity of MCF-7 human breast cancer cells by increasing hTERT expression and activity.

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    Wenbo Wang

    Full Text Available The known functions of telomerase in tumor cells include replenishing telomeric DNA and maintaining cell immortality. We have previously shown the existence of a negative correlation between human telomerase reverse transcriptase (hTERT and radiosensitivity in tumor cells. Here we set out to elucidate the molecular mechanisms underlying regulation by telomerase of radiosensitivity in MCF-7 cells. Toward this aim, yeast two-hybrid (Y2H screening of a human laryngeal squamous cell carcinoma radioresistant (Hep2R cDNA library was first performed to search for potential hTERT interacting proteins. We identified ubiquitin-conjugating enzyme E2D3 (UBE2D3 as a principle hTERT-interacting protein and validated this association biochemically. ShRNA-mediated inhibition of UBE2D3 expression attenuated MCF-7 radiosensitivity, and induced the accumulation of hTERT and cyclin D1 in these cells. Moreover, down-regulation of UBE2D3 increased hTERT activity and cell proliferation, accelerating G1 to S phase transition in MCF-7 cells. Collectively these findings suggest that UBE2D3 participates in the process of hTERT-mediated radiosensitivity in human breast cancer MCF-7 cells by regulating hTERT and cyclin D1.

  4. E3 Ligase cIAP2 Mediates Downregulation of MRE11 and Radiosensitization in Response to HDAC Inhibition in Bladder Cancer.

    Science.gov (United States)

    Nicholson, Judith; Jevons, Sarah J; Groselj, Blaz; Ellermann, Sophie; Konietzny, Rebecca; Kerr, Martin; Kessler, Benedikt M; Kiltie, Anne E

    2017-06-01

    The MRE11/RAD50/NBS1 (MRN) complex mediates DNA repair pathways, including double-strand breaks induced by radiotherapy. Meiotic recombination 11 homolog (MRE11) is downregulated by histone deacetylase inhibition (HDACi), resulting in reduced levels of DNA repair in bladder cancer cells and radiosensitization. In this study, we show that the mechanism of this downregulation is posttranslational and identify a C-terminally truncated MRE11, which is formed after HDAC inhibition as full-length MRE11 is downregulated. Truncated MRE11 was stabilized by proteasome inhibition, exhibited a decreased half-life after treatment with panobinostat, and therefore represents a newly identified intermediate induced and degraded in response to HDAC inhibition. The E3 ligase cellular inhibitor of apoptosis protein 2 (cIAP2) was upregulated in response to HDAC inhibition and was validated as a new MRE11 binding partner whose upregulation had similar effects to HDAC inhibition. cIAP2 overexpression resulted in downregulation and altered ubiquitination patterns of MRE11 and mediated radiosensitization in response to HDAC inhibition. These results highlight cIAP2 as a player in the DNA damage response as a posttranscriptional regulator of MRE11 and identify cIAP2 as a potential target for biomarker discovery or chemoradiation strategies in bladder cancer. Cancer Res; 77(11); 3027-39. ©2017 AACR . ©2017 American Association for Cancer Research.

  5. Inhibition of repopulation is not a determining factor for the radiosensitizing effects of rapamycin

    International Nuclear Information System (INIS)

    Sarkaria, J.N.; Carlson, B.L.; Mladek, A.C.

    2003-01-01

    The mammalian target of rapamycin (mTOR) is a key downstream effector of the PI3K-Akt signaling pathway, and we have previously shown that inhibition of mTOR by rapamycin significantly enhances the efficacy of prolonged fractionated radiation in U87 glioma cells grown as xenografts or spheroids. To test whether inhibition of repopulation between radiation fractions contributes to the sensitizing effects of rapamycin, the efficacy of our previous protracted radiation schedule was compared with an accelerated regimen in U87 spheroids. Regrowth of individual spheroids was tracked over time following treatment with either accelerated or protracted radiation in the presence or absence of rapamycin. As in our previous studies, treatment with 10 nM rapamycin significantly increased the time required for U87 spheroids to regrow to 10 times their original volume (22 ± 2 days [mean ± 95% CI]) compared to control (7 ± 1 days). Regrowth after protracted radiation (2 Gy every 3 days x 4; 9 ± 2 days)did not significantly differ from control treatment, while accelerated radiation (2 Gy every 4 hours x 4) modestly delayed spheroid regrowth (12 ± 2 days). Specific to our model, the relatively small difference in regrowth time between the two radiation fractionation schedules suggests that repopulation is not a major detrimental factor in the protracted radiation schedule. Interestingly, the combination of rapamycin with either protracted or accelerated RT significantly enhanced the efficacy of the radiation with regrowth times of 31 ± 4 days and 29 ± 4 days, respectively. Consistent with this in vitro data, preliminary results from an animal study suggest that treatment with a rapamycin analog and daily radiation is as effective as protracted radiation/ rapamycin schedules. Thus, any effects of rapamycin on repopulation in our model systems do not contribute significantly to the sensitizing effects of rapamycin

  6. SN-38 Acts as a Radiosensitizer for Colorectal Cancer by Inhibiting the Radiation-induced Up-regulation of HIF-1α.

    Science.gov (United States)

    Okuno, Takayuki; Kawai, Kazushige; Hata, Keisuke; Murono, Koji; Emoto, Shigenobu; Kaneko, Manabu; Sasaki, Kazuhito; Nishikawa, Takeshi; Tanaka, Toshiaki; Nozawa, Hiroaki

    2018-06-01

    Hypoxia offers resistance to therapy in human solid tumors. The aim of the study was to investigate whether SN-38, the active metabolite of irinotecan, acts as a radiosensitizer through inhibition of hypoxia-inducible factor (HIF)-1α in the human colorectal cancer (CRC) cells. HT29 and SW480 cells were cultured with SN-38 (0-4 μM) immediately after irradiation (0-8 Gy). HIF-1α expression was assessed using flow-cytometry and western blot analysis. Cell proliferation was evaluated by the calcein assay. Apoptosis and cell cycle were determined by flow-cytometry. Radiation up-regulated HIF-1α, and SN-38 inhibited the radiation-induced HIF-1α. The combination of radiation and SN-38 inhibited cell proliferation more than radiation alone; treatment with SN-38 after radiation exposure did not increase the number of apoptotic cells, whereas, it enhanced the S and G 2 /M cell-cycle arrest and decreased the population of cells in G 1 Conclusion: SN-38 inhibits the radiation-induced up-regulation of HIF-1α and acts as a radiosensitizer by inducing cell-cycle arrest in CRC cells. Copyright© 2018, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

  7. Post-irradiation DNA synthesis inhibition and G2 phase delay in radiosensitive body cells from non-Hodgkin's lymphoma patients: An indication of cell cycle defects

    International Nuclear Information System (INIS)

    Hannan, Mohammed A.; Kunhi, Mohammed; Einspenner, Michael; Khan, Bashir A.; Al-Sedairy, Sultan

    1994-01-01

    In the present study, both post-irradiation DNA synthesis and G 2 phase accumulation were analyzed in lymphoblastoid cell lines (LCLs) and fibroblast cell strains derived from (Saudi) patients with non-Hodgkin's lymphoma (NHL), ataxia telangiectasia (AT), AT heterozygotes and normal subjects. A comparison of the percent DNA synthesis inhibition (assayed by 3 H-thymidine uptake 30 min after irradiation), and a 24 h post-irradiation G 2 phase accumulation determined by flow cytometry placed the AT heterozygotes and the NHL patients in an intermediate position between the normal subjects (with maximum DNA synthesis inhibition and minimum G 2 phase accumulation) and the AT homozygotes (with minimum DNA synthesis inhibition and maximum G 2 accumulation). The similarity between AT heterozygotes and the NHL patients with respect to the two parameters studied after irradiation was statistically significant. The data indicating a moderate abnormality in the control of cell cycle progression after irradiation in the LCLs and fibroblasts from NHL patients may explain the enhanced cellular and chromosomal radiosensitivity in these patients reported by us earlier. In addition to demonstrating a link between cell cycle abnormality and radiosensitivity as a possible basis for cancer susceptibility, particularly in the NHL patients, the present studies emphasized the usefulness of the assay for 24 h post-irradiation G 2 phase accumulation developed elsewhere in characterizing AT heterozygote-like cell cycle anomaly in cancer patients irrespective of whether they carried the AT gene or any other affecting the cell cycle

  8. Radiosensitization of normoxic and hypoxic h1339 lung tumor cells by heat shock protein 90 inhibition is independent of hypoxia inducible factor-1α.

    Science.gov (United States)

    Schilling, Daniela; Bayer, Christine; Li, Wei; Molls, Michael; Vaupel, Peter; Multhoff, Gabriele

    2012-01-01

    Ionizing irradiation is a commonly accepted treatment modality for lung cancer patients. However, the clinical outcome is hampered by normal tissue toxicity and tumor hypoxia. Since tumors often have higher levels of active heat shock protein 90 (Hsp90) than normal tissues, targeting of Hsp90 might provide a promising strategy to sensitize tumors towards irradiation. Hsp90 client proteins include oncogenic signaling proteins, cell cycle activators, growth factor receptors and hypoxia inducible factor-1α (HIF-1α). Overexpression of HIF-1α is assumed to promote malignant transformation and tumor progression and thus might reduce the accessibility to radiotherapy. Herein, we describe the effects of the novel Hsp90 inhibitor NVP-AUY922 and 17-allylamino-17-demethoxygeldanamycin (17-AAG), as a control, on HIF-1α levels and radiosensitivity of lung carcinoma cells under normoxic and hypoxic conditions. NVP-AUY922 exhibited a similar biological activity to that of 17-AAG, but at only 1/10 of the dose. As expected, both inhibitors reduced basal and hypoxia-induced HIF-1α levels in EPLC-272H lung carcinoma cells. However, despite a down-regulation of HIF-1α upon Hsp90 inhibition, sensitivity towards irradiation remained unaltered in EPLC-272H cells under normoxic and hypoxic conditions. In contrast, treatment of H1339 lung carcinoma cells with NVP-AUY922 and 17-AAG resulted in a significant up-regulation of their initially high HIF-1α levels and a concomitant increase in radiosensitivity. In summary, our data show a HIF-1α-independent radiosensitization of normoxic and hypoxic H1339 lung cancer cells by Hsp90 inhibition.

  9. MicroRNA-375 Inhibits Growth and Enhances Radiosensitivity in Oral Squamous Cell Carcinoma by Targeting Insulin Like Growth Factor 1 Receptor

    Directory of Open Access Journals (Sweden)

    Bin Zhang

    2017-08-01

    Full Text Available Background: MicroRNAs (miRNAs have emerged as key players in various human biological processes, including tumorigenesis. Here, we investigated the roles of miR-375 in the pathogenesis of oral squamous cell carcinoma (OSCC. Methods: We performed quantitative real-time PCR (qRT-PCR to detect miR-375 expression in OSCC tissues and corresponding normal oral epithelial tissues and analyze the correlation of miR-375 expression with OSCC metastasis and patient’s survival. Then, the effects of miR-375 expression on proliferation, cell cycle, apoptosis and radiosensitivity in OSCC cells were determined by using MTT, flow cytometry and clonogenic survival assays. A dual-luciferase reporter assay was performed to test whether miR-375 binds to the 3’-untranslated region (3’-UTR of target mRNA. Results: The expression level of miR-375 in OSCC tissues was significantly lower than that in normal oral epithelial tissues, and low miR-375 expression was correlated with higher incidence of lymph node metastasis and poor survival of OSCC patients. Upregulation of miR-375 significantly inhibits growth, induces cell cycle arrest in G0/G1 phase, increases apoptosis and enhances radiosensitivity in OSCC cells. Analysis of luciferase activity demonstrated that miR-375 binds to the 3’-UTR of insulin like growth factor 1 receptor (IGF-1R. Small interfering RNA (shRNA-mediated IGF-1R knockdown mimics the effects of miR-375 upregulation, while overexpression of IGF-1R partially reverses those effects in OSCC cells. Conclusion: It was obviously demonstrated that miRNA-375 inhibits growth and enhances radiosensitivity in OSCC cells by targeting IGF-1R, suggesting that miR-375 may be a potential therapeutic target for OSCC patients.

  10. Radio-sensitization of esophageal cancer EC9706 cells to X ray by histone deacetylase inhibiter Trichostatin A

    International Nuclear Information System (INIS)

    Lin Xiaoli; Qin Guangyong; Fang Huasheng; Zhang Fengqiu; Ya Huiyuan

    2009-01-01

    Cell apoptosis and the expression of DNA damage repair-related genes XRCC2, ATM and Lig4 were detected separately by flow cytometry analysis and real-time fluorescence quantitative (RT-PCR), in order to investigate the effect of Trichostatin A (TSA) pre-treatment on the radiosensitivity of esophageal cancer EC9706 cells to X ray in vitro. The results indicate that pre-irradiation exposure to TSA enhances cell apoptotic rate by X ray markedly (P<0.05) and the mRNA levels of XRCC2, ATM and Lig4 (except 8Gy) are up-regulated by X ray individually (P<0.05). TSA alone and TSA in combination with X ray all reduce mRNA levels of XRCC2, ATM and Lig4. In conclusions, TSA may radio-sensitize EC9706 cells to X ray by reducing mRNA levels of XRCC2, ATM and Lig4. (authors)

  11. AZD2014 Radiosensitizes Oral Squamous Cell Carcinoma by Inhibiting AKT/mTOR Axis and Inducing G1/G2/M Cell Cycle Arrest.

    Directory of Open Access Journals (Sweden)

    Chih-Chia Yu

    Full Text Available Oral squamous cell carcinoma (OSCC is one of the most common malignant neoplasms in Taiwan. Activation of the mTOR signaling pathway has been linked to decreased radiation responsiveness in human oral cancer, thus it limits efficacy of radiotherapy. To address this question, we investigated the effect of AZD2014, a novel small molecular ATP-competitive inhibitor of mTORC1 and mTORC2 kinase, as a radiosensitizer in primary OSCC and OSCC-derived cell line models.We isolated primary tumor cells from OSCC tissues and cell lines. AZD2014 was administered with and without ionizing radiation. The radiosensitizing effect of AZD2014 were then assessed using cell viability assays, clonogenic survival assays, and cell cycle analyses. Western blotting was used to detect protein expression.Combination treatment with AZD2014 and irradiation resulted in significant reduction in OSCC cell line and primary OSCC cell colony formation due to the enhanced inhibition of AKT and both mTORC1 and mTORC2 activity. Pre-treatment with AZD2014 in irradiated oral cancer cells induced tumor cell cycle arrest at the G1 and G2/M phases, which led to disruption of cyclin D1-CDK4 and cyclin B1-CDC2 complexes. Moreover, AZD2014 synergized with radiation to promote both apoptosis and autophagy by increasing caspase-3 and LC3 in primary OSCC cells.These findings suggest that in irradiated OSCC cells, co-treatment with AZD2014, which targets mTORC1 and mTORC2 blockade, is an effective radiosensitizing strategy for oral squamous cell carcinoma.

  12. Radiosensitization and growth inhibition of cancer cells mediated by an scFv antibody gene against DNA-PKcs in vitro and in vivo

    International Nuclear Information System (INIS)

    Du, Li; Zhou, Ping-Kun; Zhou, Li-Jun; Pan, Xiu-Jie; Wang, Yu-Xiao; Xu, Qin-Zhi; Yang, Zhi-Hua; Wang, Yu; Liu, Xiao-Dan; Zhu, Mao-Xiang

    2010-01-01

    Overexpression of DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is commonly occurred in cancers and causes radioresistance and poor prognosis. In present study, the single-chain variable antibody fragments (scFv) targeting DNA-PKcs was developed for the application of radiosensitization in vitro and in vivo. A humanized semisynthetic scFv library and the phage-display antibodies technology were employed to screen DNA-PKcs scFv antibody. DNA-PKcs epitopes were predicted and cloned. A humanized semisynthetic scFv library and the phage-display antibodies technology were employed to screen DNA-PKcs scFv antibody. DNA damage repair was analyzed by comet assay and immunofluorescence detection of γH2AX foci. The radiosensitization in vivo was determined on Balb/c athymic mice transplanted tumours of HeLa cells. Four epitopes of DNA-PKcs have been predicted and expressed as the antigens, and a specific human anti-DNA-PKcs scFv antibody gene, anti-DPK3-scFv, was obtained by screening the phage antibody library using the DNA-PKcs peptide DPK3. The specificity of anti-DPK3-scFv was verified, in vitro. Transfection of HeLa cells with the anti-DPK3-scFv gene resulted in an increased sensitivity to IR, decreased repair capability of DNA double-strand breaks (DSB) detected by comet assay and immunofluorescence detection of γH2AX foci. Moreover, the kinase activity of DNA-PKcs was inhibited by anti-DPK3-scFv, which was displayed by the decreased phosphorylation levels of its target Akt/S473 and the autophosphorylation of DNA-PKcs on S2056 induced by radiation. Measurement of the growth and apoptosis rates showed that anti-DPK3-scFv enhanced the sensitivity of tumours transplanted in Balb/c athymic mice to radiation therapy. The antiproliferation and radiosensitizing effects of anti-DPK3-scFv via targeting DNA-PKcs make it very appealing for the development as a novel biological radiosensitizer for cancer therapeutic potential

  13. Resveratrol enhances radiosensitivity of human non-small cell lung cancer NCI-H838 cells accompanied by inhibition of nuclear factor-kappa B activation

    International Nuclear Information System (INIS)

    Liao, Hui-Fen; Kuo Cheng-Deng; Yang, Yuh-Cheng; Lin, Chin-Ping; Tai, Hung-Chi; Chen, Yu-Jen; Chen, Yu-Yawn

    2005-01-01

    Resveratrol, a polyphenol in red wine, possesses many pharmacological activities including cardio-protection, chemoprevention, anti-tumor effects, and nuclear factor-kappa B (NF-κB) inactivation. The present study was designed to evaluate the effects and possible mechanism of resveratrol in enhancing radiosensitivity of lung cancer cells. Human non-small cell lung cancer NCI-H838 cells were irradiated with or without resveratrol pretreatment. The surviving fraction and sensitizer enhancement ratio (SER) were estimated by using a colony formation assay and linear-quadratic model. The cell-cycle distribution was evaluated by using prospidium iodide staining and flow cytometry. An enzyme-linked immunosorbent assay (ELISA)-based assay with immobilized oligonucleotide was performed to assess the DNA binding activity of NF-κB. Resveratrol had no direct growth-inhibitory effect on NCI-H838 cells treated for 24 hours with doses up to 25 μM. Pretreatment with resveratrol significantly enhanced cell killing by radiation, with an SER up to 2.2. Radiation activated NF-κB, an effect reversed by resveratrol pretreatment. Resveratrol resulted in a decrease of cells in the G 0 /G 1 phase and an increase in the S phase. Our results demonstrate that resveratrol enhances the radiosensitivity of NCI-H838 cells accompanied by NF-κB inhibition and S-phase arrest. (author)

  14. Downregulation of miR-210 expression inhibits proliferation, induces apoptosis and enhances radiosensitivity in hypoxic human hepatoma cells in vitro

    International Nuclear Information System (INIS)

    Yang, Wei; Sun, Ting; Cao, Jianping; Liu, Fenju; Tian, Ye; Zhu, Wei

    2012-01-01

    Hypoxia is a common feature of solid tumors and an important contributor to tumor radioresistance. miR-210 is the most consistently and robustly induced microRNA under hypoxia in different types of tumor cells and normal cells. In the present study, to explore the feasibility of miR-210 as an effective therapeutic target, lentiviral-mediated anti-sense miR-210 gene transfer technique was employed to downregulate miR-210 expression in hypoxic human hepatoma SMMC-7721, HepG2 and HuH7 cells, and phenotypic changes of which were analyzed. Hypoxia led to an increased hypoxia inducible factor-1α (HIF-1α) and miR-210 expression and cell arrest in the G 0 /G 1 phase in all cell lines. miR-210 downregulation significantly suppressed cell viability, induced cell arrest in the G 0 /G 1 phase, increased apoptotic rate and enhanced radiosensitivity in hypoxic human hepatoma cells. Moreover, apoptosis-inducing factor, mitochondrion-associated, 3 (AIFM3) was identified as a direct target gene of miR-210. AIFM3 downregulation by siRNA attenuated radiation induced apoptosis in miR-210 downregulated hypoxic human hepatoma cells. Taken together, these data suggest that miR-210 might be a potential therapeutic target and specific inhibition of miR-210 expression in combination with radiotherapy might be expected to exert strong anti-tumor effect on hypoxic human hepatoma cells. -- Highlights: ► miR-210 downregulation radiosensitized hypoxic hepatoma. ► AIFM3 was identified as a direct target gene of miR-210. ► miR-210 might be a therapeutic target to hypoxic hepatoma.

  15. Downregulation of miR-210 expression inhibits proliferation, induces apoptosis and enhances radiosensitivity in hypoxic human hepatoma cells in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Wei, E-mail: detachedy@yahoo.com.cn [Department of Radiobiology, School of Radiological Medicine and Protection, Soochow University, Suzhou (China); Sun, Ting [Brain and Nerve Research Laboratory, The First Affiliated Hospital, Soochow University, Suzhou (China); Cao, Jianping; Liu, Fenju [Department of Radiobiology, School of Radiological Medicine and Protection, Soochow University, Suzhou (China); Tian, Ye [Department of Radiotherapy and Oncology, The Second Affiliated Hospital, Soochow University, Suzhou (China); Zhu, Wei [Department of Radiobiology, School of Radiological Medicine and Protection, Soochow University, Suzhou (China)

    2012-05-01

    Hypoxia is a common feature of solid tumors and an important contributor to tumor radioresistance. miR-210 is the most consistently and robustly induced microRNA under hypoxia in different types of tumor cells and normal cells. In the present study, to explore the feasibility of miR-210 as an effective therapeutic target, lentiviral-mediated anti-sense miR-210 gene transfer technique was employed to downregulate miR-210 expression in hypoxic human hepatoma SMMC-7721, HepG2 and HuH7 cells, and phenotypic changes of which were analyzed. Hypoxia led to an increased hypoxia inducible factor-1{alpha} (HIF-1{alpha}) and miR-210 expression and cell arrest in the G{sub 0}/G{sub 1} phase in all cell lines. miR-210 downregulation significantly suppressed cell viability, induced cell arrest in the G{sub 0}/G{sub 1} phase, increased apoptotic rate and enhanced radiosensitivity in hypoxic human hepatoma cells. Moreover, apoptosis-inducing factor, mitochondrion-associated, 3 (AIFM3) was identified as a direct target gene of miR-210. AIFM3 downregulation by siRNA attenuated radiation induced apoptosis in miR-210 downregulated hypoxic human hepatoma cells. Taken together, these data suggest that miR-210 might be a potential therapeutic target and specific inhibition of miR-210 expression in combination with radiotherapy might be expected to exert strong anti-tumor effect on hypoxic human hepatoma cells. -- Highlights: Black-Right-Pointing-Pointer miR-210 downregulation radiosensitized hypoxic hepatoma. Black-Right-Pointing-Pointer AIFM3 was identified as a direct target gene of miR-210. Black-Right-Pointing-Pointer miR-210 might be a therapeutic target to hypoxic hepatoma.

  16. Membrane specific drugs as radiosensitizers

    Energy Technology Data Exchange (ETDEWEB)

    George, K.C.; Mishra, K.P.; Shenoy, M.A.; Singh, B.B.; Srinivasan, V.T.; Verma, N.C.

    1981-01-01

    Procaine, paracetamol, and chlorpromazine showed inhibition of post irradiation repair. The chlorpromazie effect could be further augmented by treatment of cells with procaine. Chlorpromazine was also found to be preferentially toxic to hypoxid bacterial cells, and the survivors showed extreme radiosensitivity to gamma rays. Chlorpromazine was found to inhibit tumour growth in swiss mice when given intraperitoneally as well as when injected directly into the tumour. When combined with single x-ray doses, significant radiosensitization was observed in two in vivo tumours sarcoma 180A and fibrosarcoma. These results indicated that chlorpromazine may prove a good drug for combined chemo-radiotherapy of solid tumours. Investigations continued studying various aspects such as effectiveness in other tumour lines, distribution in healthy and tumour bearing animals, hyperthermia and drug combination effects, and encapsulation of the drug in artificial liposomes and blood cells. (ERB)

  17. Glyoxylic compounds as radiosensitizers of hypoxic cells

    International Nuclear Information System (INIS)

    Cornago, M.P.; Lopez Zumel, M.C.; Alvarez, M.V.; Izquierdo, M.C.

    1990-01-01

    The radiosensitizing effect of five glyoxal derivatives on the survival of TC-SV40 cells has been measured, under aerobic and hypoxic conditions. A toxicity study was previously performed in order to use nontoxic concentrations. The OER for the TC-SV40 cells was 2.74. None of the glyoxylic compounds showed radiosensitizing activity under aerobic conditions while in hypoxia their radiosensitizing factors decreased in the order phenylglyoxylic acid (1.68 at 8 x 10(-3) mole dm-3) greater than phenylglyoxal (1.55 at 5 x 10(-6) mole dm-3) greater than 2-2' furil (1.48 at 5 x 10(-5) mole dm-3) greater than glyoxylic acid (1.39 at 1 x 10(-3) mole dm-3) greater than glyoxal (1.30 at 5 x 10(-5) mole dm-3). The dose-modifying factors were also determined at two equimolar concentrations 5 x 10(-5) and 5 x 10(-6) mole dm-3. A concentration effect was noticed for all the compounds although their relative radiosensitizing activity kept, independently of the concentration, the same order noted above. Glyoxals with aromatic or heterocyclic rings exert a greater radiosensitization than the others. The acidic compounds have less radiosensitizing activity than their aldehydic counterparts. Interaction of these glyoxals with NPSH cellular groups was tested and the low degree of inhibition shows that this mechanism would contribute very little, if any, to the radiosensitization effect

  18. Radiosensitivity of higher plants

    International Nuclear Information System (INIS)

    Feng Zhijie

    1992-11-01

    The general views on radiosensitivity of higher plants have been introduced from published references. The radiosensitivity varies with species, varieties and organs or tissues. The main factors of determining the radiosensitivity in different species are nucleus volume, chromosome volume, DNA content and endogenous compounds. The self-repair ability of DNA damage and chemical group of biological molecules, such as -SH thiohydroxy of proteins, are main factors to determine the radiosensitivity in different varieties. The moisture, oxygen, temperature radiosensitizer and protector are important external factors for radiosensitivity. Both the multiple target model and Chadwick-Leenhouts model are ideal mathematical models for describing the radiosensitivity of higher plants and the latter has more clear significance in biology

  19. Regulator of G-protein signaling 5 (RGS5) inhibits cell proliferation and enhances radiosensitivity of human lung cancer cells

    International Nuclear Information System (INIS)

    Xu Zumin; Wang Jin; Zuo Yufang; Yu Zhonghua; Peng Fang; Hu Xiao; Zhou Qichao; Ma Honglian; Bao Yong; Chen Ming

    2014-01-01

    Objective: To investigate the effects of regulator and the underlying molecular mechanisms of G-protein signaling 5 (RGS5) on radiation response in human lung cancer cells. Methods: The effects of RGS5 on viability were determined by MTT assay, and apoptosis rate was detected by flow cytometry, in human lung cancer cells. The combined effect of ionizing radiation and RGS5 on tumor cells was detected by colony formation assay. The protein expression was detected by Western blot. Results: RGS5 overexpression remarkably inhibited the survival of human lung cancer cells, and the growth inhibition rate of RGS5 overexpression on A549 and Calu-3 cells were 44.4% (F = 29.18, P < 0.05) and 39.27% (F = 23.04, P < 0.05) at 48 h, and 54.3%(F = 103.45, P < 0.05), 44.7%(F = 108.02, P < 0.05) at 72 h post-irradiation, respectively. RGS5 might exert its inhibitory effects on human lung cancer cells by inducing tumor cell apoptosis, while the apoptotic cells rate in A549 and Calu-3 cells in control group, pTRiEX group and pTRiEX-RGS5 group were (1.3±0.2)%, (3.4±0.6)%, (19.6±2.3)% (F = 86.62, P < 0.05), and (3.2±0.8)%, (3.0±0.9)%, (12.8±1.8)% (F = 28.80, P < 0.05) at 36 h post-irradiation, respectively. Furthermore, RGS5 could sensitize the lung cancer cells to radiation. Conclusions: RGS5 might play an inhibitory role in human lung cancer cell proliferation, which may explain the pathoclinical observation thet high expression of RGSS is a favorable prognostic factor in NSCLC patients. In addition, RGS5 also enhance the anti-tumor effects of radiation in human lung cancer cells. (authors)

  20. Activating and inhibiting connections in biological network dynamics

    Directory of Open Access Journals (Sweden)

    Knight Rob

    2008-12-01

    Full Text Available Abstract Background Many studies of biochemical networks have analyzed network topology. Such work has suggested that specific types of network wiring may increase network robustness and therefore confer a selective advantage. However, knowledge of network topology does not allow one to predict network dynamical behavior – for example, whether deleting a protein from a signaling network would maintain the network's dynamical behavior, or induce oscillations or chaos. Results Here we report that the balance between activating and inhibiting connections is important in determining whether network dynamics reach steady state or oscillate. We use a simple dynamical model of a network of interacting genes or proteins. Using the model, we study random networks, networks selected for robust dynamics, and examples of biological network topologies. The fraction of activating connections influences whether the network dynamics reach steady state or oscillate. Conclusion The activating fraction may predispose a network to oscillate or reach steady state, and neutral evolution or selection of this parameter may affect the behavior of biological networks. This principle may unify the dynamics of a wide range of cellular networks. Reviewers Reviewed by Sergei Maslov, Eugene Koonin, and Yu (Brandon Xia (nominated by Mark Gerstein. For the full reviews, please go to the Reviewers' comments section.

  1. Spike propagation in driven chain networks with dominant global inhibition

    International Nuclear Information System (INIS)

    Chang Wonil; Jin, Dezhe Z.

    2009-01-01

    Spike propagation in chain networks is usually studied in the synfire regime, in which successive groups of neurons are synaptically activated sequentially through the unidirectional excitatory connections. Here we study the dynamics of chain networks with dominant global feedback inhibition that prevents the synfire activity. Neural activity is driven by suprathreshold external inputs. We analytically and numerically demonstrate that spike propagation along the chain is a unique dynamical attractor in a wide parameter regime. The strong inhibition permits a robust winner-take-all propagation in the case of multiple chains competing via the inhibition.

  2. Genistein, a tyrosine kinase inhibitor, enhanced radiosensitivity in human esophageal cancer cell lines in vitro: Possible involvement of inhibition of survival signal transduction pathways

    International Nuclear Information System (INIS)

    Akimoto, Tetsuo; Nonaka, Tetsuo; Ishikawa, Hitoshi; Sakurai, Hideyuki; Saitoh, Jun-ichi; Takahashi, Takeo; Mitsuhashi, Norio

    2001-01-01

    Purpose: The effect of genistein, a tyrosine kinase inhibitor, on radiosensitivity was examined, especially focusing on 'survival signal transduction pathways'. Methods and Materials: Two human esophageal squamous cell cancer cell lines, TE-1 (p53, mutant) and TE-2 (p53, wild), were used. Radiosensitivity was determined by clonogenic assay, and activation of survival signals was examined by Western blot. Results: Genistein (30 μM) greatly enhanced radiosensitivity in these cell lines by suppressing radiation-induced activation of survival signals, p42/p44 extracellular signal-regulated kinase and AKT/PKB. Significant increase in the percentage of apoptotic cells and increased poly[ADP-ribose] polymerase cleavage were observed in TE-2, but not in TE-1 even after combination of genistein with irradiation. In terms of changes in expression of p53-related proteins, increase in expression of Bax and decrease in that of Bcl-2 were observed in TE-2 but not in TE-1, suggesting that the main mode of cell death induced by genistein in a cell line with wild type p53 differed from that with mutant p53. Conclusions: This study suggested that survival signals, including p42/p44 ERK and AKT/PKB, may be involved in determining radiosensitivity, and genistein would be a potent therapeutic agent that has an enhancing effect on radiation

  3. Radiosensitivities of sensitized lymphocytes

    International Nuclear Information System (INIS)

    Taniguchi, Kazuto

    1979-01-01

    Immunization of mice with cell antigens such as allogeneic tumor cells or xenogeneic erythrocytes raises a variety of immune reactions mediated by T lymphocytes: i.e. delayed type hypersensitivity (DTH), cytotoxicity, and antibody production. The radiosensitivities of these reactions were examined in mice exposed to 600 R x-irradiation a few hours before or after immunization. 1) DTH to xenogeneic erythrocytes, as demonstrated by footpad reaction, was not suppressed by irradiation 3 h before or after immunization. DTH to allogeneic tumor cells, as demonstrated by a migration inhibition test, hardly developed in mice that had been irradiated before or after immunization. It may have belonged to distinct types of delayed reactions which were mediated by distinct subpopulations of T lymphocytes. 2) Cytotoxicity against allogeneic cells and xenogeneic erythrocytes showed almost the same radiosensitivity. It was scarcely detected in mice that had been irradiated before immunization. However, a low but definite degree of cytotoxicity was detected in mice that had been irradiated only a few hours after immunization. Solubilized allogeneic cells instead of native cells were used as immunizing antigens. It was also possible for precursor cells with cytotoxicity to acquire a radioresistant nature by immunization of solubilized antigens, but native cells were required as stimulation for radioresistant precursor cells to differentiated into nature cytotoxic effector cells. 3) Antibody production against xenogeneic erythrocytes or allogeneic cells was almost completely depleted in mice that had been irradiated before or after immunization. It is possible that antibody production essentially requires cell division and clonal expansion of B lymphocytes. (Bell, E.)

  4. Biophysical radiosensitization

    International Nuclear Information System (INIS)

    Vladescu, C.; Apetroae, M.

    1983-01-01

    Experimental studies on normal and tumor-bearing rats revealed that chronic treatment with hydroquinone (5 mg/kg/day) inhibited catalase activity in liver, spleen, blood, and H 18R tumor. 3 H-hydroquinone (1.5 μCi/g body weight) showed tumor specificity, with maximum radioactivity in the tumor at 1 h after administration. The biological half-time of 3 H-hydroquinone in the tumor was 2 h, but there seems to exist a longer component, since 24 h after administration, some 30% of the maximum radioactivity could be detected in the tumor. Hydroquinone treatment produces a specific inhibition of catalase in the tumor and a higher degree of oxygenation at this level. These findings support the assumption that the mechanism of action of hydroquinone as an anticancer agent is achieved mainly via peroxide production. The oxygenation of the hypoxic tumoral tissue is done at non-toxic levels of hydroquinone, through a natural and specific biophysical pathway, recommanding hydroquinone for combined anticancer treatment (radiotherapy and chemotherapy). (orig.)

  5. ADPRT inhibitors and hyperthermia as radiosensitizers

    International Nuclear Information System (INIS)

    Jonsson, G.G.

    1985-01-01

    Hyperthermia given in combination with gamma radiation has given considerable improvement in the therapeutic results for treatment of malignant tumors. The mechanism behind the hyperthermia effect is probably operative at the tissue level as well as at the molecular level. The metabolism of NAD + in relation to the activity of the chromosomal enzyme ADP-ribosyl transferase (ADPRT) has been studied as a possible molecular mechanism for this effect. The ADPRT activity was measured after radiosensitization with both hyperthermia and nicotinamide, which is a potent inhibitor of ADPRT. The results indicate that hyperthermia can improve the effect of radiotherapy by reducing the supply of NAD + , which is a co-substrate for ADPRT, while nicotinamide functions as a radiosensitizing agent by direct inhibition of the enzyme. The hypothesis is discussed in the thesis where inhibition of ADPRT might increase the radiosensitivity because the radiation-induced DNA damage can not be repaired with normal efficiency. The function of nicotinamide as a radiosensitizer was verified by studies on C3H mice with transplanted spontaneous mammary tumors. Because nicotinamide is not toxic, it seems quite attractive to test this vitamin as a radiosensitizing agent against human tumors. (251 refs.) (author)

  6. Targeting Mcl-1 for Radiosensitization of Pancreatic Cancers

    Directory of Open Access Journals (Sweden)

    Dongping Wei

    2015-02-01

    Full Text Available In order to identify targets whose inhibition may enhance the efficacy of chemoradiation in pancreatic cancer, we previously conducted an RNAi library screen of 8,800 genes. We identified Mcl-1 (myeloid cell leukemia-1, an anti-apoptotic member of the Bcl-2 family, as a target for sensitizing pancreatic cancer cells to chemoradiation. In the present study we investigated Mcl-1 inhibition by either genetic or pharmacological approaches as a radiosensitizing strategy in pancreatic cancer cells. Mcl-1 depletion by siRNA produced significant radiosensitization in BxPC-3 and Panc-1 cells in association with Caspase-3 activation and PARP cleavage, but only minimal radiosensitization in MiaPaCa-2 cells. We next tested the ability of the recently identified, selective, small molecule inhibitor of Mcl-1, UMI77, to radiosensitize in pancreatic cancer cells. UMI77 caused dissociation of Mcl-1 from the pro-apoptotic protein Bak and produced significant radiosensitization in BxPC-3 and Panc-1 cells, but minimal radiosensitization in MiaPaCa-2 cells. Radiosensitization by UMI77 was associated with Caspase-3 activation and PARP cleavage. Importantly, UMI77 did not radiosensitize normal small intestinal cells. In contrast, ABT-737, an established inhibitor of Bcl-2, Bcl-XL, and Bcl-w, failed to radiosensitize pancreatic cancer cells suggesting the unique importance of Mcl-1 relative to other Bcl-2 family members to radiation survival in pancreatic cancer cells. Taken together, these results validate Mcl-1 as a target for radiosensitization of pancreatic cancer cells and demonstrate the ability of small molecules which bind the canonical BH3 groove of Mcl-1, causing displacement of Mcl-1 from Bak, to selectively radiosensitize pancreatic cancer cells.

  7. Inhibition delay increases neural network capacity through Stirling transform

    Science.gov (United States)

    Nogaret, Alain; King, Alastair

    2018-03-01

    Inhibitory neural networks are found to encode high volumes of information through delayed inhibition. We show that inhibition delay increases storage capacity through a Stirling transform of the minimum capacity which stabilizes locally coherent oscillations. We obtain both the exact and asymptotic formulas for the total number of dynamic attractors. Our results predict a (ln2) -N-fold increase in capacity for an N -neuron network and demonstrate high-density associative memories which host a maximum number of oscillations in analog neural devices.

  8. Functional neural networks underlying response inhibition in adolescents and adults.

    Science.gov (United States)

    Stevens, Michael C; Kiehl, Kent A; Pearlson, Godfrey D; Calhoun, Vince D

    2007-07-19

    This study provides the first description of neural network dynamics associated with response inhibition in healthy adolescents and adults. Functional and effective connectivity analyses of whole brain hemodynamic activity elicited during performance of a Go/No-Go task were used to identify functionally integrated neural networks and characterize their causal interactions. Three response inhibition circuits formed a hierarchical, inter-dependent system wherein thalamic modulation of input to premotor cortex by fronto-striatal regions led to response suppression. Adolescents differed from adults in the degree of network engagement, regional fronto-striatal-thalamic connectivity, and network dynamics. We identify and characterize several age-related differences in the function of neural circuits that are associated with behavioral performance changes across adolescent development.

  9. In vivo radiosensitization by diethyldithiocarbamate

    International Nuclear Information System (INIS)

    Kent, C.R.; Blekkenhorst, G.H.

    1988-01-01

    Diethyldithiocarbamate (DDC) has been suggested to have both radiosensitizing (due to superoxide dismutase (SOD) inhibition) and radioprotective properties. We have studied the activity of SOD up to 24 h after intratumoral administration of 50, 100, 150, and 300 mg/kg DDC in 3-methylcholanthrene-induced tumors in BALB/c mice. Maximal inhibition of SOD (8% of control) was obtained 1 h after administration of 100 mg/kg DDC. Tumor response to DDC and X irradiation was assessed using a tumor growth-delay assay, after 11 Gy 100-kVp X rays given up to 24 h after DDC administration. Radiation-induced tumor growth delay (7.11 +/- 1.76 days) was enhanced only when tumors were irradiated 2-4 h after 50 mg/kg DDC. When higher doses of DDC were used, tumor cure was noted when DDC was injected 1-6 h before irradiation. We suggest our findings are consistent with radiosensitization being due to SOD inhibition, but that if insufficient time is allowed between DDC injection and irradiation, the sensitization is masked by a radioprotective effect. We believe that further investigations as to the therapeutic potential of DDC in human patients with cancer are warranted

  10. Radiosensitizers and protectors

    International Nuclear Information System (INIS)

    Nori, D.; Kim, J.H.; Hilaris, B.; Chu, F.C.

    1987-01-01

    Over the past decades, various physical, biological, and clinical strategies have been investigated to improve the therapeutic effectiveness of radiation. One of these efforts has been to develop chemical radiosensitizers and protectors. In the broadest sense, a radiation sensitizer is any agent that enhances the cytolethal effects of radiation. Drugs that selectively protect tissues from radiation injury are under active study. This chapter briefly reviews the present status of chemical radiosensitizers and protectors. The discussion of sensitizers will be limited to the oxic cell and hypoxic cell radiosensitizers and their clinical applications

  11. A Critical Role of the PTEN/PDGF Signaling Network for the Regulation of Radiosensitivity in Adenocarcinoma of the Prostate

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, Michael, E-mail: mechristense@uwalumni.com [Department of Radiation Oncology, Wayne State University School of Medicine, Barbara Ann Karmanos Cancer Center, Detroit, Michigan (United States); Najy, Abdo J. [Department of Pathology, Wayne State University School of Medicine, Barbara Ann Karmanos Cancer Center, Detroit, Michigan (United States); Snyder, Michael; Movilla, Lisa S. [Department of Radiation Oncology, Wayne State University School of Medicine, Barbara Ann Karmanos Cancer Center, Detroit, Michigan (United States); Kim, Hyeong-Reh Choi [Department of Pathology, Wayne State University School of Medicine, Barbara Ann Karmanos Cancer Center, Detroit, Michigan (United States)

    2014-01-01

    Purpose: Loss or mutation of the phosphate and tensin homologue (PTEN) is a common genetic abnormality in prostate cancer (PCa) and induces platelet-derived growth factor D (PDGF D) signaling. We examined the role of the PTEN/PDGF axis on radioresponse using a murine PTEN null prostate epithelial cell model. Methods and Materials: PTEN wild-type (PTEN{sup +/+}) and PTEN knockout (PTEN{sup −/−}) murine prostate epithelial cell lines were used to examine the relationship between the PTEN status and radiosensitivity and also to modulate the PDGF D expression levels. PTEN{sup −/−} cells were transduced with a small hairpin RNA (shRNA) lentiviral vector containing either scrambled nucleotides (SCRM) or sequences targeted to PDGF D (shPDGF D). Tumorigenesis and morphogenesis of these cell lines were evaluated in vivo via subcutaneous injection of male nude mice and in vitro using Matrigel 3-dimensional (3D) culture. Effects of irradiation on clonogenic survival, cell migration, and invasion were measured with respect to the PTEN status and the PDGF D expression level. In addition, apoptosis and cell cycle redistribution were examined as potential mechanisms for differences seen. Results: PTEN{sup −/−} cells were highly tumorigenic in animals and effectively formed foci in 3D culture. Importantly, loss of PDGF D in these cell lines drastically diminished these phenotypes. Furthermore, PTEN{sup −/−} cells demonstrated increased clonogenic survival in vitro compared to PTEN{sup +/+}, and attenuation of PDGF D significantly reversed this radioresistant phenotype. PTEN{sup −/−} cells displayed greater migratory and invasive potential at baseline as well as after irradiation. Both the basal and radiation-induced migratory and invasive phenotypes in PTEN{sup −/−} cells required PDGF D expression. Interestingly, these differences were independent of apoptosis and cell cycle redistribution, as they showed no significant difference. Conclusions: We propose

  12. Radiosensitivity of fingermillet genotypes

    Energy Technology Data Exchange (ETDEWEB)

    Raveendran, T S; Nagarajan, C; Appadurai, R; Prasad, M N; Sundaresan, N [Tamil Nadu Agricultural Univ., Coimbatore (India)

    1984-07-01

    Varietal differences in radiosensitivity were observed in a study involving 4 genotypes of fingermillet (Eleusine coracana (Linn.) Gaertn.) subjected to gamma-irradiation. Harder seeds were found to tolerate a higher dose of the mutagen.

  13. TNF-α inhibits trophoblast integration into endothelial cellular networks.

    Science.gov (United States)

    Xu, B; Nakhla, S; Makris, A; Hennessy, A

    2011-03-01

    Preeclampsia has been linked to shallow trophoblast invasion and failure of uterine spiral artery transformation. Interaction between trophoblast cells and maternal uterine endothelium is critically important for this remodelling. The aim of our study was to investigate the effect of TNF-α on the interactions of trophoblast-derived JEG-3 cells into capillary-like cellular networks. We have employed an in vitro trophoblast-endothelial cell co-culture model to quantify trophoblast integration into endothelial cellular networks and to investigate the effects of TNF-α. Controlled co-cultures were also treated with anti-TNF-α antibody (5 μg/ml) to specifically block the effect of TNF-α. The invasion was evaluated by performing quantitative PCR (Q-PCR) to analyse gene expression of matrix metalloproteinases-2 (MMP-2), MMP-9, tissue inhibitor of matrix metalloproteinase (TIMP)-1, integrins (α(1)β(1) and α(6)β(4)), plasminogen activator inhibitor (PAI)-1, E-cadherin and VE-cadherin. JEG-3 cell integration into endothelial networks was significantly inhibited by exogenous TNF-α. The inhibition was observed in the range of 0.2-5 ng/ml, to a maximum 56% inhibition at the highest concentration. This inhibition was reversed by anti-TNF-α antibody. Q-PCR analysis showed that mRNA expression of integrins α(1)β(1) and MMP-2 was significantly decreased. VE-cadherin mRNA expression was significantly up-regulated (32-80%, p integration into maternal endothelial cellular networks, and this process involves the inhibition of MMP-2 and a failure of integrins switch from α(6)β(4) to α(1)β(1.) These molecular correlations reflect the changes identified in human preeclampsia. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Radiosensitivity of mouse germ cells

    International Nuclear Information System (INIS)

    Matsuda, Yoichi; Takeuchi, Toyoko; Maemori, Mamiko; Seki, Naohiko; Tobari, Izuo

    1991-01-01

    To estimate radiosensitivity of mouse germ cells the analysis of chromosome aberrations was performed at diakinesis-metaphase I of spermatocytes and first-cleavage metaphase of one-cell embryos after exposure to radiations at various stages of primary spermatocytes and spermatids. The result provided evidence that there are two major types of DNA damage in X-irradiated sperm : (1) short-lived DNA lesions ; the lesions are subject to repair inhibition by agents added in G 1 , and are converted into chromosome-type aberrations during G 1 , and (2) long-lived DNA lesions ; the lesions persist until S phase and repair of the lesions is inhibited by caffeine, hydroxyurea and arabinofuranosyl cytosine in G 2 . The characteristic of X-ray damage induced in spermiogenic stage and repair mechanism for the damage in the fertilized egg were discussed comparing with the results with two chemicals, methyl methanesulfonate (MMS) and mitomycin C (MMC). (J.P.N.)

  15. Radiosensitizers: rationale and potential

    International Nuclear Information System (INIS)

    Brown, J.M.

    1981-01-01

    This paper briefly reviews agents that are capable of sensitizing hypoxic cells to radiation and chemotherapeutic agents. The first part is a synopsis of the development of hypoxic radiosensitizers, which concludes that misonidazole can be effective against human tumors. Unfortunately, neurotoxicity limits its effectiveness in humans because the dose that can be given in conjunction with daily fractionated radiation is five to ten times lower than is required for full radiosensitization of the hypoxic cells. The second part covers our recent efforts to develop a drug that does not produce such limiting neurotoxicity. The primary rationale of our program was to synthesize a drug with a short plasma half-life that was too hydrophilic to cross the blood-brain barrier but was able to penetrate tumors and radiosensitize hypoxic cells. From this program, a new drug, SR-2508, has been found that is as efficient as misonidazole in its radiosensitizing ability, but is four to ten times less toxic. Finally, the potential of radiosensitizers not only as agents that can sensitize tumor cells to radiation, but also as agents that can specifically sensitize tumors to chemotherapeutic agents, is discussed. In addition, these drugs may be potential cytotoxic agents that produce toxicity only in solid tumors

  16. Genetic components for radiosensitivity. Gene expression in radiosensitive monocygotic twins. Final report

    International Nuclear Information System (INIS)

    Dikomey, Ekkehard

    2012-01-01

    The underlying hypothesis of this project was that the variation of individual radiosensitivity is determined by the different expression of single gens. This concept was tested using 60 monozygotic twin pairs, followed by an evaluation with 80 prostate cancer patients. Radiosensitivity was assessed for both G0- as well as G2-phase using chromosomal assays. G0- radiosensitivity is determined by lethal chromosomal aberrations and reflects the individual amount of cell killing, while G2-sensitivity is determined by chromatid breaks and is taken as an indicator of individual cancer risk. For both populations, G0- and G2-radiosensitivity are characterized by substantial variation with a CV of 11 and 14% or 27 and 21%, respectively. While the mean G0-sensitivity is the same for both populations, there is a slight difference for G2. The slightly higher value of G2-sensitivity found for prostate cancer patients might result from the higher age of this group. For both populations gene expression profiles were determined using the Affymetrix chip HG-U133+2.0. Overall gene expression was characterized by a huge variation covering more than four decades. However, for single genes, expression showed little variation with CV generally ranging only between 2 and 8%. Analysis of data using several different methods revealed that variation of both G0- as well as G2-radiosensitivity cannot be ascribed to the different expression of single genes. For twins, random forests can be used to identify 8 to 10 genes than are relevant either for G0- or G2-radiosensitivity. However, these genes cannot be confirmed by an evaluation with 80 prostate cancer patients. This finding clearly demonstrates that the hypothesis, due to which variation of individual radiosensitivity is caused by different expression of single genes, has to be rejected. It appears more likely that this parameter is determined by complex interactions of several genes in functional networks. (orig.)

  17. Inhibition of DNA-PKcs enhances radiosensitivity and increases the levels of ATM and ATR in NSCLC cells exposed to carbon ion irradiation.

    Science.gov (United States)

    Yang, Lina; Liu, Yuanyuan; Sun, Chao; Yang, Xinrui; Yang, Zhen; Ran, Juntao; Zhang, Qiuning; Zhang, Hong; Wang, Xinyu; Wang, Xiaohu

    2015-11-01

    Non-small cell lung cancer (NSCLC) exhibits radioresistance to conventional rays, due to its DNA damage repair systems. NSCLC may potentially be sensitized to radiation treatment by reducing those factors that continuously enhance the repair of damaged DNA. In the present study, normal lung fibroblast MRC-5 and lung cancer A549 cells were treated with NU7026 and CGK733, which are inhibitors of the DNA-dependent protein kinase catalytic subunit (PKcs) and ataxia telangiectasia mutated (ATM) and ataxia telangiectasia and Rad3-related (ATR), respectively, followed by exposure to X-rays and carbon ion irradiation. The cytotoxic activity, cell survival rate, DNA damage repair ability, cell cycle arrest and apoptosis rate of the treated cells were analyzed with MTT assay, colony formation assay, immunofluorescence and flow cytometry, respectively. The transcription and translation levels of the ATM, ATR and DNA-PKcs genes were detected by reverse transcription-quantitative polymerase chain reaction and western blotting, respectively. The results indicated that the radiosensitivity and DNA repair ability of A549 cells were reduced, and the percentages of apoptotic cells and those arrested at the G 2 /M phase of the cell cycle were significantly increased, following ionizing radiation with inhibitor-pretreatment. The expression levels of ATM, ATR, DNA-PKcs and phosphorylated histone H2AX, a biomarker for DNA double-strand breaks, were all upregulated at the transcriptional or translational level in A549 cells treated with carbon ion irradiation, compared with the control and X-rays-treated cells. In addition, the treatment with 5-50 µM NU7026 or CGK733 did not produce any obvious cytotoxicity in MRC-5 cells, and the effect of the DNA-PKcs-inhibitor on enhancing the radiosensitivity of A549 cells was stronger than that observed for the ATM and ATR-inhibitor. These findings demonstrated a minor role for ATM and ATR in radiation-induced cell death, since the upregulation of

  18. Development of Radiosensitizer using farnesyltransferase inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Jong Seok; Choe, Yong Kyung; Han, Mi Young; Kim, Kwang Dong [Korea Research Institute of Bioscience and Biotechnology, Taejon (Korea)

    1999-03-01

    We selected some compounds that were reported to have an activity of farneyltransferase inhibitor and tested the hypothesis that they might be used to radiosensitize cells transformed by ras oncogenes. The inhibition of ras processing using some, but not all, inhibitors resulted in higher levels of cell death after {gamma}-irradiation and increased radiosensitivity in H-ras-transformed NIH3T3 cells and MCF-10A human tumor cells. They did not induce additional cell death in control cells that doe not have ras mutation. Furthermore, the treatment of inhibitors alone induced a weak G0/G1 block, whereas inhibitors in combination with {gamma}-irradiation induced an additional enrichment in the G2/M phase of the cell cycle that typically represents irradiation-induced growth arrest. At present, the underling mechanism by which the farnesylltransferase inhibitors exert radiosensitizing effect is not known. In summary, our results suggest and lead to the possibility that some of farnesylation inhibitors may prove clinically useful not only as antitumor agents, but also radiosensitizers of tumors whose growth is dependent on ras function. (author). 15 refs., 10 figs., 4 tabs.

  19. Loss of inhibition in sensorimotor networks in focal hand dystonia

    Directory of Open Access Journals (Sweden)

    Cecile Gallea

    2018-01-01

    Interpretation: Impairments of GABAergic neurotransmission in the cerebellum and the sensorimotor cortical areas could explain different aspects of loss of inhibitory control in FHD, the former being involved in maladaptive plasticity, the latter in surround inhibition. Reorganization of the inferior prefrontal cortices, part of the associative network, might be compensatory for the loss of inhibitory control in sensorimotor circuits. These findings suggest that cerebellar and cerebral GABAergic abnormalities could play a role in the functional imbalance of striato-cerebello-cortical loops in dystonia.

  20. Radiosensitivity in plants

    International Nuclear Information System (INIS)

    Nauman, A.F.

    1979-01-01

    The report presents a compilation of available data on the sensitivity of plants to ionizing radiation, and provides basic information on methods of determining such sensitivities, or of estimating radiosensitivities by calcuation of the nuclear factors upon which they depend. The scope of the data presented here is necessarily limited to the most generally useful radiobiological end points and to the most commonly-used types of radiation. Many of the factors which influence radiosensitivity, particularly nuclear factors, will be discussed. Emphasis will be upon whole-plant studies done at Brookhaven National Laboratory by A.H. Sparrow and his associates, since these studies are the source of most of the available radiosensitivity data and of all the sensitivity predictions listed here. Data presented here include summaries of experimentally-determined radiosensitivities at various end points for both herbaceous and woody higher plants, and for a few species of ferns and lower plants. The algae and fungi have not been considered here due to space limitations

  1. Radiosensitivity in plants

    Energy Technology Data Exchange (ETDEWEB)

    Nauman, A F

    1979-01-01

    The report presents a compilation of available data on the sensitivity of plants to ionizing radiation, and provides basic information on methods of determining such sensitivities, or of estimating radiosensitivities by calcuation of the nuclear factors upon which they depend. The scope of the data presented here is necessarily limited to the most generally useful radiobiological end points and to the most commonly-used types of radiation. Many of the factors which influence radiosensitivity, particularly nuclear factors, will be discussed. Emphasis will be upon whole-plant studies done at Brookhaven National Laboratory by A.H. Sparrow and his associates, since these studies are the source of most of the available radiosensitivity data and of all the sensitivity predictions listed here. Data presented here include summaries of experimentally-determined radiosensitivities at various end points for both herbaceous and woody higher plants, and for a few species of ferns and lower plants. The algae and fungi have not been considered here due to space limitations.

  2. Atomoxetine restores the response inhibition network in Parkinson's disease.

    Science.gov (United States)

    Rae, Charlotte L; Nombela, Cristina; Rodríguez, Patricia Vázquez; Ye, Zheng; Hughes, Laura E; Jones, P Simon; Ham, Timothy; Rittman, Timothy; Coyle-Gilchrist, Ian; Regenthal, Ralf; Sahakian, Barbara J; Barker, Roger A; Robbins, Trevor W; Rowe, James B

    2016-08-01

    Parkinson's disease impairs the inhibition of responses, and whilst impulsivity is mild for some patients, severe impulse control disorders affect ∼10% of cases. Based on preclinical models we proposed that noradrenergic denervation contributes to the impairment of response inhibition, via changes in the prefrontal cortex and its subcortical connections. Previous work in Parkinson's disease found that the selective noradrenaline reuptake inhibitor atomoxetine could improve response inhibition, gambling decisions and reflection impulsivity. Here we tested the hypotheses that atomoxetine can restore functional brain networks for response inhibition in Parkinson's disease, and that both structural and functional connectivity determine the behavioural effect. In a randomized, double-blind placebo-controlled crossover study, 19 patients with mild-to-moderate idiopathic Parkinson's disease underwent functional magnetic resonance imaging during a stop-signal task, while on their usual dopaminergic therapy. Patients received 40 mg atomoxetine or placebo, orally. This regimen anticipates that noradrenergic therapies for behavioural symptoms would be adjunctive to, not a replacement for, dopaminergic therapy. Twenty matched control participants provided normative data. Arterial spin labelling identified no significant changes in regional perfusion. We assessed functional interactions between key frontal and subcortical brain areas for response inhibition, by comparing 20 dynamic causal models of the response inhibition network, inverted to the functional magnetic resonance imaging data and compared using random effects model selection. We found that the normal interaction between pre-supplementary motor cortex and the inferior frontal gyrus was absent in Parkinson's disease patients on placebo (despite dopaminergic therapy), but this connection was restored by atomoxetine. The behavioural change in response inhibition (improvement indicated by reduced stop-signal reaction

  3. Acute LSD effects on response inhibition neural networks.

    Science.gov (United States)

    Schmidt, A; Müller, F; Lenz, C; Dolder, P C; Schmid, Y; Zanchi, D; Lang, U E; Liechti, M E; Borgwardt, S

    2017-10-02

    Recent evidence shows that the serotonin 2A receptor (5-hydroxytryptamine2A receptor, 5-HT2AR) is critically involved in the formation of visual hallucinations and cognitive impairments in lysergic acid diethylamide (LSD)-induced states and neuropsychiatric diseases. However, the interaction between 5-HT2AR activation, cognitive impairments and visual hallucinations is still poorly understood. This study explored the effect of 5-HT2AR activation on response inhibition neural networks in healthy subjects by using LSD and further tested whether brain activation during response inhibition under LSD exposure was related to LSD-induced visual hallucinations. In a double-blind, randomized, placebo-controlled, cross-over study, LSD (100 µg) and placebo were administered to 18 healthy subjects. Response inhibition was assessed using a functional magnetic resonance imaging Go/No-Go task. LSD-induced visual hallucinations were measured using the 5 Dimensions of Altered States of Consciousness (5D-ASC) questionnaire. Relative to placebo, LSD administration impaired inhibitory performance and reduced brain activation in the right middle temporal gyrus, superior/middle/inferior frontal gyrus and anterior cingulate cortex and in the left superior frontal and postcentral gyrus and cerebellum. Parahippocampal activation during response inhibition was differently related to inhibitory performance after placebo and LSD administration. Finally, activation in the left superior frontal gyrus under LSD exposure was negatively related to LSD-induced cognitive impairments and visual imagery. Our findings show that 5-HT2AR activation by LSD leads to a hippocampal-prefrontal cortex-mediated breakdown of inhibitory processing, which might subsequently promote the formation of LSD-induced visual imageries. These findings help to better understand the neuropsychopharmacological mechanisms of visual hallucinations in LSD-induced states and neuropsychiatric disorders.

  4. Radiosensitivity of hepatocellular carcinoma

    International Nuclear Information System (INIS)

    Hennequin, C.; Quero, L.; Rivera, S.

    2011-01-01

    The frequency of hepatocellular carcinoma (HCC) is increasing in the western world and the role of radiotherapy is more and more discussed. Classically, hepatocellular carcinoma was considered as a radioresistant tumour: in fact, modern radio-biologic studies, performed on cell lines directly established from patients, showed that hepatocellular carcinoma has the same radiosensitivity than the other epithelial tumours. From clinical studies, its α/β ratio has been estimated to be around 15 Gy. Radiosensitivity of normal hepatic parenchyma is now well evaluated and some accurate NTCP models are available to guide hepatic irradiation. The biology of hepatocellular carcinoma is also better described: the combination of radiotherapy and targeted therapies will be a promising approach in the near future. (authors)

  5. Radiosensitivity of cells

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, P [Radiation Biology Section, Chester Beatty Research Institute, Royal Cancer Hospital, London (United Kingdom)

    1960-07-15

    The mechanism by which radiation kills cells must be investigated with the goal to make possible to devise means to alter the radiosensitivity of cells. The object of our investigation, supported by IAEA, is to try and find the reasons for the variation in sensitivity between different cells. Once we know the reason for the differences in radiosensitivity of different micro-organisms we can begin to look rationally for ways of enhancing the radiation response of the more sensitive organisms. An investigation of this type has implications far beyond food sterilization, as it cannot fail to provide fundamental facts about radiation injury to cells in general. Cancer researchers have looked for many years for means of sensitizing cancer cells to radiation

  6. Radiosensitivity of cells

    International Nuclear Information System (INIS)

    Alexander, P.

    1960-01-01

    The mechanism by which radiation kills cells must be investigated with the goal to make possible to devise means to alter the radiosensitivity of cells. The object of our investigation, supported by IAEA, is to try and find the reasons for the variation in sensitivity between different cells. Once we know the reason for the differences in radiosensitivity of different micro-organisms we can begin to look rationally for ways of enhancing the radiation response of the more sensitive organisms. An investigation of this type has implications far beyond food sterilization, as it cannot fail to provide fundamental facts about radiation injury to cells in general. Cancer researchers have looked for many years for means of sensitizing cancer cells to radiation

  7. Enhanced Radiosensitivity of Tumor Cells Treated with Vanadate in Vitro

    International Nuclear Information System (INIS)

    Lee, Myung Za; Lee, Won Young

    1994-01-01

    Intracellular ions which have a major role in cellular function have been reported to affect repair of radiation damage. Recently it has been reported that ouabain sensitizes A549 tumor cells hut not CCL-120 normal cells to radiation. Ouabain inhibits the Na+-K+-pump rapidly thus it increases intracellular Na concentration. Vanadate which is distributed extensively in almost all living organisms in known to be a Na+-K+-ATPase inhibitors. This study was performed to see any change in radiosensitivity of tumor cell by vanadate and any role of Na+-K+-ATPase in radiosensitization. Experiments have been carried out by pretreatment with vanadate in human cell line(A549, JMG) and mouse cell line(L1210, spleen). For the cell survival MTT assay was performed for A549 and JMG cell and trypan blue dye exclusion test for L120, and spleen cells. Measurements of Na+-K+-ATPase activity in control, vanadate treated cell, radiation treated cell (9 Gy for A549 and JMG, 2 Gy for L1201, spleen), and combined 10-6 M vanadate and radiation treated cells were done. The results were summarized as follows. 1. L1210 cell was most radiosensitive, and spleen cell and JMG cell were intermediate, and A549 cell was least radiosensitive. 2. Minimum or cytotoxicity was seen with vanadate below concentration of 10-6 M. 3. In A549 cells there was a little change in radiosensitivity with treatment of vanadate. However radiation sensitization was shown in low dose level of radiation i. E. 2-Gy. In JMG cells no change in radiosensitivity was noted. Both L1210 and spleen cell had radiosensitization but change was greater in tumor cell. 4. Na+-K+-ATPase activity was inhibited significantly in tumor cell by treatment of vanadate. 5. Radiation itself inhibited Na+-K+-ATPase activity of tumor cell with high Na+- K+-ATPase concention. Increase in radiosensitivity by vanadate was closely associated with original Na+-K+-ATPase contents. From the above results vanadate had little cytotoxicity and it sensitized

  8. Radiosensitivity and genes

    Energy Technology Data Exchange (ETDEWEB)

    Qiyue, Hu; Mingyue, Lun [Suzhou Medical Coll., JS (China)

    1995-07-01

    Reported effects of some oncogenes, tumour suppressor genes and DNA repair genes on sensitivity of cells to ionizing radiation are reviewed. The role of oncogenes in cellular response to irradiation is discussed, especially the extensively studied oncogenes such as the ras gene family. For tumour suppressor genes, mainly the p53, which is increasingly implicated as a gene affecting radiosensitivity, is reviewed. It is considered that there is a cell cycle checkpoint determinant which is postulated to be able to arrest the irradiated cells in G{sub 1} phase to allow them to repair damage before they undergo DNA synthesis. So far there are six DNA repair genes which have been cloned in mammalian cells, but only one, XRCC1, appears to be involved in repair of human X-ray damage. XRCC1 can correct high sisterchromatid exchange levels when transferred into EM{sub 9} cells, but its expression seems to have no correlation with radiosensitivity of human neck and head tumour cells. Radiosensitivity is an intricate issue which may involve many factors. A scheme of cellular reactions after exposure to irradiation is proposed to indicate a possible sequence of events initiated by ionizing radiation.

  9. Radiosensitivity and genes

    International Nuclear Information System (INIS)

    Hu Qiyue; Lun Mingyue

    1995-07-01

    Reported effects of some oncogenes, tumour suppressor genes and DNA repair genes on sensitivity of cells to ionizing radiation are reviewed. The role of oncogenes in cellular response to irradiation is discussed, especially the extensively studied oncogenes such as the ras gene family. For tumour suppressor genes, mainly the p53, which is increasingly implicated as a gene affecting radiosensitivity, is reviewed. It is considered that there is a cell cycle checkpoint determinant which is postulated to be able to arrest the irradiated cells in G 1 phase to allow them to repair damage before they undergo DNA synthesis. So far there are six DNA repair genes which have been cloned in mammalian cells, but only one, XRCC1, appears to be involved in repair of human X-ray damage. XRCC1 can correct high sisterchromatid exchange levels when transferred into EM 9 cells, but its expression seems to have no correlation with radiosensitivity of human neck and head tumour cells. Radiosensitivity is an intricate issue which may involve many factors. A scheme of cellular reactions after exposure to irradiation is proposed to indicate a possible sequence of events initiated by ionizing radiation

  10. Radiosensitivity of amphibia

    Energy Technology Data Exchange (ETDEWEB)

    Muramatsu, S [National Inst. of Radiological Sciences, Chiba (Japan)

    1975-04-01

    Radiosensitivity (semi-lethal dose) and the damages of radiation in the amphibia were studied by /sup 3/H-TdR from the standpoint of cellular kinetics. The cell mitosis cycle of the amphibia required a long time. The functional cell regeneration and the physiological function of the cell were slower than in mice. The reason for the low radiosensitivity of the amphibia was discussed relative to the environmental factor of temperature. Because the amphibia change body temperature according to environmental temperature, the danger of radiation damage, the actual lethal dose and the period of survival were influenced by the environmental temperature. Acute radiation danger to amphibia was essentially the same as the danger to mammalia, both young and old. LD/sub 50/ irradiation effects varied among the species. The cell regeneration, turn over, and the mitosis in the amphibia, were affected by environmental temperature, however, the courses proceeded slower than those of the mammalia. Therefore, the question remains, whether the comparison of the radiosensitivities of amphibia with other classes of animal by LDsub(50/30) irradiation was appropriate.

  11. Correlation of RAD51 and radiosensitization of methotrexate

    International Nuclear Information System (INIS)

    Du Liqing; Bai Jianqiang; Liu Qiang; Wang Yan; Zhao Peng; Chen Fenghua; Wang Hong; Fan Feiyue

    2012-01-01

    Objective: To evaluate the correlation between homologous recombination repair protein RAD51 and methotrexate-enhanced radiosensitivity. Methods: Western blot and RT-PCR assays were used to detect RAD51 expression in HOS osteosarcoma cells exposed to γ-ray irradiation alone and in combination with methotrexate. Colony formation assay was used to test the survival fraction of HOS cells exposed to γ-rays and methotrexate. Results: Methotrexate inhibited both protein and RNA expressions of RAD51, and the combination of radiation and methotrexate enhanced the inhibition of RAD51 expression. Moreover, transfection of cells with RAD51 gene decreased cellular sensitivity to methotrexate and γ-rays. The sensitizer enhancement ratios after irradiation in combination with methotrexate were 1.51 and 0.99, respectively. Methotrexate was a preferred radiosensitizer to HOS cell. Conclusions: RAD51 might be involved in the methotrexate-enhanced radiosensitivity. (authors)

  12. Regulating Cortical Oscillations in an Inhibition-Stabilized Network.

    Science.gov (United States)

    Jadi, Monika P; Sejnowski, Terrence J

    2014-04-21

    Understanding the anatomical and functional architecture of the brain is essential for designing neurally inspired intelligent systems. Theoretical and empirical studies suggest a role for narrowband oscillations in shaping the functional architecture of the brain through their role in coding and communication of information. Such oscillations are ubiquitous signals in the electrical activity recorded from the brain. In the cortex, oscillations detected in the gamma range (30-80 Hz) are modulated by behavioral states and sensory features in complex ways. How is this regulation achieved? Although several underlying principles for the genesis of these oscillations have been proposed, a unifying account for their regulation has remained elusive. In a network of excitatory and inhibitory neurons operating in an inhibition-stabilized regime, we show that strongly superlinear responses of inhibitory neurons facilitate bidirectional regulation of oscillation frequency and power. In such a network, the balance of drives to the excitatory and inhibitory populations determines how the power and frequency of oscillations are modulated. The model accounts for the puzzling increase in their frequency with the salience of visual stimuli, and a decrease with their size. Oscillations in our model grow stronger as the mean firing level is reduced, accounting for the size dependence of visually evoked gamma rhythms, and suggesting a role for oscillations in improving the signal-to-noise ratio (SNR) of signals in the brain. Empirically testing such predictions is still challenging, and implementing the proposed coding and communication strategies in neuromorphic systems could assist in our understanding of the biological system.

  13. Novel radiosensitizers for locally advanced epithelial tumors: inhibition of the PI3K/Akt survival pathway in tumor cells and in tumor-associated endothelial cells as a novel treatment strategy?

    International Nuclear Information System (INIS)

    Riesterer, Oliver; Tenzer, Angela; Zingg, Daniel; Hofstetter, Barbara; Vuong, Van; Pruschy, Martin; Bodis, Stephan

    2004-01-01

    In locally advanced epithelial malignancies, local control can be achieved with high doses of radiotherapy (RT). Concurrent chemoradiotherapy can improve tumor control in selected solid epithelial adult tumors; however, treatment-related toxicity is of major concern and the therapeutic window often small. Therefore, novel pharmacologic radiosensitizers with a tumor-specific molecular target and a broad therapeutic window are attractive. Because of clonal heterogeneity and the high mutation rate of these tumors, combined treatment with single molecular target radiosensitizers and RT are unlikely to improve sustained local tumor control substantially. Therefore, radiosensitizers modulating entire tumor cell survival pathways in epithelial tumors are of potential clinical use. We discuss the preclinical efficacy and the mechanism of three different, potential radiosensitizers targeting the PTEN/PI3K/Akt survival pathway. These compounds were initially thought to act as single-target agents against growth factor receptors (PKI 166 and PTK 787) or protein kinase C isoforms (PKC 412). We describe an additional target for these compounds. PKI 166 (an epidermal growth factor [EGF] receptor inhibitor) and PKC 412, target the PTEN/PI3K/Akt pathway mainly in tumor cells, and PTK 787 (a vascular endothelial growth factor [VEGF] receptor inhibitor) in endothelial cells. Even for these broader range molecular radiosensitizers, the benefit could be restricted to human epithelial tumor cell clones with a distinct molecular profile. Therefore, these potential radiosensitizers have to be carefully tested in specific model systems before introduction in early clinical trials

  14. Normal inhibition of DNA synthesis following γ-irradiation of radiosensitive cell lines from patients with Down's syndrome and Alzheimer's disease

    International Nuclear Information System (INIS)

    Lavin, M.F.; Le poidevin, P.; Chen, P.C.; Bates, P.

    1989-01-01

    Inhibition of DNA synthesis was studied in γ-iradiated lymphoblastoid cells from patients with Alzheimer's disease and Down's syndrome. A normal biphasic pattern of inhibition was observed over a dose range of 0-4 krad of γ-rays in all of the cell lines 3 out of 4 Down's and all the Alzheimer's cell lines were shown to be hypersensitive to ionizing radiation based on induced chromosomal aberrations. Increased G2 phase delay, comparable to that occurring in ataxia-telangiectasia cells, was observed for some of the cell lines, after exposure to γ-rays. Contrary to other data in the literature these results demonstrate that radioresistand DNA synthesis is not an intrinsic feature of all disorders characterized by radiosensitivitey. (author).; 25 refs.; 2 figs.; 1 tab

  15. The radiosensitizing effect of doranidazole on human colorectal cancer cells exposed to high doses of irradiation

    International Nuclear Information System (INIS)

    Zhang, Li; Gong, Aimin; Ji, Jun; Wu, Yuanyuan; Zhu, Xiaoyu; Lv, Suqing; Lv, Hongzhu; Sun, Xizhuo

    2007-01-01

    This paper investigates the effects of a new radiosensitizer, doranidazole, and enhancing irradiation on colorectal cancer cells. The radiosensitizing effect of doranidazole was determined using colony formation and propidium iodide (PI) assays to measure cell growth inhibition and the cell killing effect of human colorectal cancer cell lines exposed to high doses of γ-ray irradiation under hypoxic conditions in vitro. Fluorescence staining and cell migration assays were also used to assess the radiosensitizing effect. Cell proliferation evaluated by clonogenic survival curves was significantly inhibited by 5 mmol/L doranidazole, particularly at doses ranging from 10 to 30 Gy of irradiation. The radiosensitizing effect of doranidazole on colorectal cancer cells occurs in a time- and dose-dependent manner. Doranidazole also inhibited the mobility of cell invasion and migration. Doranidazole can enhance the killing effect and the cell growth inhibition of colorectal cancer after high-dose irradiation in a time and dose-dependent manner

  16. Chromosomes, cancer and radiosensitivity

    International Nuclear Information System (INIS)

    Samouhos, E.

    1983-01-01

    Some specific chromosomal abnormalities are associated with certain cancers. The earliest description of such a specific association is the one of the Philadelphia chromosome and myelogenous leukemia (1960). Other congenital karyotype abnormalities are associated with specific cancers. Examples of these are Down's syndrome with leukemia and Klinefelter's syndrome with male breast cancer. Genetic diseases of increased chromosome breakage, or of defective chromosome repair, are associated with greatly increased cancer incidence. Three such diseases have been recognized: 1) Fanconi's anemia, associated with leukemias and lymphomas, 2) Bloom's syndrome, associated with acute leukemias and lymphosarcoma, and 3) ataxia telangiectasia, associated with Hodgkin's disease, leukemia, and lymphosarcomas. Ten percent of individuals with ataxia telangiectasia will develop one of these neoplasms. Individuals with certain of these syndromes display an unusually high radiosensitivity. Radiation therapy for cancers has been fatal in patients who received as low as 3000 rad. This remarkable radiosensitivity has been quantitated in cell cultures from such cases. Evidence suggests that the apparent sensitivity may reflect subnormal ability to repair radiation damage. The rapid proliferation of information in this field stems from the interdigitation of many disciplines and specialties, including cytogenetics, cell biology, molecular biology, epidemiology, radiobiology, and several others. This paper is intended for clinicians; it presents a structured analytic scheme for correlating and classifying this multidisciplinary information as it becomes available

  17. Radiosensitization by hematocrit manipulation

    International Nuclear Information System (INIS)

    Hirst, D.G.; Hazlehurst, J.L.; Brown, J.M.

    1985-01-01

    The authors show that tumors in mice adapt to anemia in a rather complex manner. Radiosensitivity may be lower, higher or equal to normal depending on when the anemia is induced prior to irradiation. The authors study these changes in radiosensitivity which occur during a period of anemia followed by the restoration of the hematocrit. When mice were made anemic immediately before irradiation, their tumors were very resistant, but the resistance was lost over the following 24 hrs even though the anemia was maintained. If mice which had been anemic for 24 hrs were retransfused to normal levels with red blood cells immediately before irradiation, their tumors were considerably more sensitive than normal. As the interval between retransfusion and irradiation was increased, sensitization was rapidly lost so that by 24 hrs sensitivity was the same as that of control tumors. They attribute this loss of sensitization to rapid tumor growth in response to a restored oxygen supply so that new hypoxic cells are created. The implications of this for the treatment of the anemic patient are discussed

  18. Sensing radiosensitivity of human epidermal stem cells

    International Nuclear Information System (INIS)

    Rachidi, Walid; Harfourche, Ghida; Lemaitre, Gilles; Amiot, Franck; Vaigot, Pierre; Martin, Michele T.

    2007-01-01

    Purpose: Radiosensitivity of stem cells is a matter of debate. For mouse somatic stem cells, both radiosensitive and radioresistant stem cells have been described. By contrast, the response of human stem cells to radiation has been poorly studied. As epidermis is a radiosensitive tissue, we evaluated in the present work the radiosensitivity of cell populations enriched for epithelial stem cells of human epidermis. Methods and materials: The total keratinocyte population was enzymatically isolated from normal human skin. We used flow cytometry and antibodies against cell surface markers to isolate basal cell populations from human foreskin. Cell survival was measured after a dose of 2 Gy with the XTT assay at 72 h after exposure and with a clonogenic assay at 2 weeks. Transcriptome analysis using oligonucleotide microarrays was performed to assess the genomic cell responses to radiation. Results: Cell sorting based on two membrane proteins, α6 integrin and the transferrin receptor CD71, allowed isolation of keratinocyte populations enriched for the two types of cells found in the basal layer of epidermis: stem cells and progenitors. Both the XTT assay and the clonogenic assay showed that the stem cells were radioresistant whereas the progenitors were radiosensitive. We made the hypothesis that upstream DNA damage signalling might be different in the stem cells and used microarray technology to test this hypothesis. The stem cells exhibited a much more reduced gene response to a dose of 2 Gy than the progenitors, as we found that 6% of the spotted genes were regulated in the stem cells and 20% in the progenitors. Using Ingenuity Pathway Analysis software, we found that radiation exposure induced very specific pathways in the stem cells. The most striking responses were the repression of a network of genes involved in apoptosis and the induction of a network of cytokines and growth factors. Conclusion: These results show for the first time that keratinocyte

  19. Icotinib hydrochloride enhances chemo- and radiosensitivity by inhibiting EGFR signaling and attenuating RAD51 expression and function in Hela S3 cells

    Directory of Open Access Journals (Sweden)

    Wang X

    2018-03-01

    Full Text Available Xuanxuan Wang, Yanjun Gu, Hai Liu, Liming Shi, Xiaonan Sun Department of Radiation Oncology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, China Background: Radiotherapy and cisplatin-based chemotherapy are currently considered as standard treatments employed for advanced cervical cancer (CC. However, patients with local recurrence or distant metastasis continue to have poor outcomes. EGFR overexpression correlated with chemo/radioresistance, and disease failure has been well proved in the previous studies. Hence, the aim of this study was to explore the therapeutic efficacy and underlying mechanism of the sensitization to radiation or cisplatin of icotinib hydrochloride (IH, a high-selective EGFR tyrosine kinase inhibitor (TKI, in the Hela S3 human CC cell line.Methods: Cell proliferation was measured with cell counting kit-8 (CCK-8 assay. Flow cytometry analysis was performed to examine cell cycle distribution and apoptosis. The phosphorylation of EGFR and its downstream signaling molecules were measured by Western blot analysis. γ-H2AX foci and RAD51 foci in the cellular nucleus were visualized using immunofluoresence staining. Expression levels of RAD51 in the whole cells and subceullar fractions were detected to demonstrate the impact of IH on DNA repair. Results: IH can significantly inhibit cell proliferation, redistribute cell cycle, enhance apoptosis and impair DNA damage response of Hela S3 cells following radiation or cisplatin treatment through suppressing the activation of the EGFR signaling pathway and attenuating the expression and function of homologous recombination (HR protein RAD51.Conclusion: This study suggests that IH is a potential sensitizer in radiotherapy and cisplatin-based chemotherapy for CC and RAD51 may serve as a prognosis biomarker for this combination treatment. Keywords: icotinib hydrochloride, cervical cancer, EGFR, radiotherapy, chemotherapy

  20. ATM-induced radiosensitization in vitro and in vivo

    International Nuclear Information System (INIS)

    Choi, E. K.; Ahn, S. D.; Rhee, Y. H.; Chung, H. S.; Ha, S. W; Song, C. W.; Griffin, R. J.; Park, H. J.

    2003-01-01

    It has been known that ATM plays a central role in response of cells to ionizing radiation by enhancing DNA repair. We have investigated the feasibility of increasing radiosensitivity of tumor cells with the use of ATM inhibitors such as caffeine, pentoxifylline and wortmannin. Human colorectal cancer RKO.C cells and RKO-ATM cells (RKO cells overexpressing ATM) were used in the present study. The clonogenic cell survival in vitro indicated that RKO-ATM cells were markedly radioresistant than RKO.C cells. Treatment with 3 mM of caffeine significantly increased the radiosensitivity of cells, particulary the RKO-ATM cells, so that the radiosensitivity of RKO.C cells and RKO-ATM cells were almost similar. The radiation induced G2/M arrest in RKO-ATM cells was noticeably longer than that in RKO.C cells and caffeine treatment significantly reduced the length of the radiation induced G2/M arrest in both RKO.C and RKO-ATM cells. Pentoxifylline and wortmannin were also less effective than caffeine to radiosensitize RKO.C or RKO-ATM cells. However, wortmannin was more effective than caffeine against human lung adenocarcinoma A549 cells indicating the efficacy of ATM inhibitor to increase radiosensitivity is cell line dependent. For in vivo study, RKO.C cells were injected s.c. into the hind-leg of BALB/c-nuslc nude mice, and allowed to grow to 130mm3 tumor. The mice were i.p. injected with caffeine solution or saline and the tumors irradiated with 10 Gy of X-rays. The radiation induced growth delay was markedly increased by 1-2 mg/g of caffeine. It was concluded that caffeine increases radiosensitivity of tumor cells by inhibiting ATM kinase function, thereby inhibiting DNA repair, that occurs during the G2/M arrest after radiation

  1. Radiosensitivity of neuroblastoma

    International Nuclear Information System (INIS)

    Deacon, J.M.; Wilson, P.; Steel, G.G.

    1985-01-01

    Neuroblastoma is known to be clinically radioresponsive: it is possible to obtain local tumour control with relatively small doses of radiation. The main therapeutic problem, however, is one of metastatic disease, where in spite of modern combination chemotherapy, the prognosis remains poor. Systemic therapy with either drugs or radiation is dose-limited by toxicity to bone marrow stem cells. However, the advent of new technology which enables tumour cells to be removed from infiltrated marrow prior to autologous bone marrow ''rescue'' allows dose escalation, and makes the use of systemic irradiation in the treatment of stage IV disease feasible. The objective of this study was to investigate the radiobiology of neuroblastoma in detail, including intrinsic cellular radiosensitivity, repair capacity, and extrinsic dose-modifying factors which may affect tumour response in vivo. Cells at three levels of organisation were used: single cell suspensions multicellular tumour spheroids; and xenografts grown in immune-suppressed mice

  2. The molecular basis of radiosensitivity

    International Nuclear Information System (INIS)

    McMillan, T.J.

    1989-01-01

    This paper considers how DNA damage induced by ionising radiation is processed within the cell. The current view of radiobiology is discussed. The author explains the molecular processes that underlie the differences in radiosensitivity

  3. Studies on Drosophila radiosensitive strains

    International Nuclear Information System (INIS)

    Varentsova, E.P.; Zakharov, I.A.

    1976-01-01

    45 of radiosensitive strains of Drosophila melanogaster were isolated by Curly/Lobe technique after EMS treatment of Livadia population males. The lethality of non-Curly late larvae after gamma-irradiation (4000r) characterized radiosensitivity strains. Most of them exhibited higher frequency of the spontaneous dominant lethals (up to 69%). The males of 6 strains were semi-sterile. 5 of these strains exhibited higher frequency of X-chromosome non-disjunction

  4. Radiosensitization by the histone deacetylase inhibitor vorinostat under hypoxia and with capecitabine in experimental colorectal carcinoma

    International Nuclear Information System (INIS)

    Saelen, Marie Grøn; Ree, Anne Hansen; Kristian, Alexandr; Fleten, Karianne Giller; Furre, Torbjørn; Hektoen, Helga Helseth; Flatmark, Kjersti

    2012-01-01

    The histone deacetylase inhibitor vorinostat is a candidate radiosensitizer in locally advanced rectal cancer (LARC). Radiosensitivity is critically influenced by hypoxia; hence, it is important to evaluate the efficacy of potential radiosensitizers under variable tissue oxygenation. Since fluoropyrimidine-based chemoradiotherapy (CRT) is the only clinically validated regimen in LARC, efficacy in combination with this established regimen should be assessed in preclinical models before a candidate drug enters clinical trials. Radiosensitization by vorinostat under hypoxia was studied in four colorectal carcinoma cell lines and in one colorectal carcinoma xenograft model by analysis of clonogenic survival and tumor growth delay, respectively. Radiosensitizing effects of vorinostat in combination with capecitabine were assessed by evaluation of tumor growth delay in two colorectal carcinoma xenografts models. Under hypoxia, radiosensitization by vorinostat was demonstrated in vitro in terms of decreased clonogenicity and in vivo as inhibition of tumor growth. Adding vorinostat to capecitabine-based CRT increased radiosensitivity of xenografts in terms of inhibited tumor growth. Vorinostat sensitized colorectal carcinoma cells to radiation under hypoxia in vitro and in vivo and improved therapeutic efficacy in combination with capecitabine-based CRT in vivo. The results encourage implementation of vorinostat into CRT in LARC trials

  5. Radiosensitization by the histone deacetylase inhibitor vorinostat under hypoxia and with capecitabine in experimental colorectal carcinoma.

    Science.gov (United States)

    Saelen, Marie Grøn; Ree, Anne Hansen; Kristian, Alexandr; Fleten, Karianne Giller; Furre, Torbjørn; Hektoen, Helga Helseth; Flatmark, Kjersti

    2012-09-27

    The histone deacetylase inhibitor vorinostat is a candidate radiosensitizer in locally advanced rectal cancer (LARC). Radiosensitivity is critically influenced by hypoxia; hence, it is important to evaluate the efficacy of potential radiosensitizers under variable tissue oxygenation. Since fluoropyrimidine-based chemoradiotherapy (CRT) is the only clinically validated regimen in LARC, efficacy in combination with this established regimen should be assessed in preclinical models before a candidate drug enters clinical trials. Radiosensitization by vorinostat under hypoxia was studied in four colorectal carcinoma cell lines and in one colorectal carcinoma xenograft model by analysis of clonogenic survival and tumor growth delay, respectively. Radiosensitizing effects of vorinostat in combination with capecitabine were assessed by evaluation of tumor growth delay in two colorectal carcinoma xenografts models. Under hypoxia, radiosensitization by vorinostat was demonstrated in vitro in terms of decreased clonogenicity and in vivo as inhibition of tumor growth. Adding vorinostat to capecitabine-based CRT increased radiosensitivity of xenografts in terms of inhibited tumor growth. Vorinostat sensitized colorectal carcinoma cells to radiation under hypoxia in vitro and in vivo and improved therapeutic efficacy in combination with capecitabine-based CRT in vivo. The results encourage implementation of vorinostat into CRT in LARC trials.

  6. Radiosensitization by the histone deacetylase inhibitor vorinostat under hypoxia and with capecitabine in experimental colorectal carcinoma

    Directory of Open Access Journals (Sweden)

    Saelen Marie

    2012-09-01

    Full Text Available Abstract Background The histone deacetylase inhibitor vorinostat is a candidate radiosensitizer in locally advanced rectal cancer (LARC. Radiosensitivity is critically influenced by hypoxia; hence, it is important to evaluate the efficacy of potential radiosensitizers under variable tissue oxygenation. Since fluoropyrimidine-based chemoradiotherapy (CRT is the only clinically validated regimen in LARC, efficacy in combination with this established regimen should be assessed in preclinical models before a candidate drug enters clinical trials. Methods Radiosensitization by vorinostat under hypoxia was studied in four colorectal carcinoma cell lines and in one colorectal carcinoma xenograft model by analysis of clonogenic survival and tumor growth delay, respectively. Radiosensitizing effects of vorinostat in combination with capecitabine were assessed by evaluation of tumor growth delay in two colorectal carcinoma xenografts models. Results Under hypoxia, radiosensitization by vorinostat was demonstrated in vitro in terms of decreased clonogenicity and in vivo as inhibition of tumor growth. Adding vorinostat to capecitabine-based CRT increased radiosensitivity of xenografts in terms of inhibited tumor growth. Conclusions Vorinostat sensitized colorectal carcinoma cells to radiation under hypoxia in vitro and in vivo and improved therapeutic efficacy in combination with capecitabine-based CRT in vivo. The results encourage implementation of vorinostat into CRT in LARC trials.

  7. The role of propranolol as a radiosensitizer in gastric cancer treatment

    Directory of Open Access Journals (Sweden)

    Liao XH

    2018-03-01

    Full Text Available Xinhua Liao, Prakash Chaudhary, Guanglin Qiu, Xiangming Che, Lin Fan General Surgery Department, First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China Purpose: The National Comprehensive Cancer Network guidelines indicate that radiotherapy in gastric cancer shows limited effectiveness at reducing the growth of gastric cancer. Therefore, enhancing the sensitivity and effect of radiotherapy with propranolol, a β-adrenoceptor antagonist, could reduce tumor growth. The role of propranolol as a radiosensitizer has not been adequately studied; therefore, the purpose of the present study is to evaluate the effect of propranolol as a radiosensitizer against gastric cancer in vivo. Methods: Sixty-four male nude mice bearing tumor xenografts were randomly divided into four groups. Cell culture was performed using the human gastric adenocarcinoma cell line SGC-7901. Mice with tumor xenografts were treated with propranolol, isoproterenol, and radiation. The data for tumor weight and volume were obtained for statistical analyses. Furthermore, the expression levels of COX-2, NF-κB, VEGF, and EGFR were examined using immunohistochemical techniques and Western blotting.Results: The growth in the volume and weight of the tumor was lower in mouse models treated with propranolol and radiation therapy compared to the other groups. Decreased expression of NF-κB was also observed in treatment groups where both propranolol and radiation were used, leading to the reduction of COX-2, EGFR, and VEGF expression compared to that in the other groups.Conclusion: The present study indicated that propranolol potentiates the antitumor effects of radiotherapy in gastric cancer by inhibiting NF-κB expression and its downstream genes: VEGF, EGFR, and COX-2. Keywords: propranolol, radiosensitizer, gastric cancer, radiation therapy 

  8. Control of a local neural network by feedforward and feedback inhibition

    NARCIS (Netherlands)

    Remme, M.W.H.; Wadman, W.J.

    2004-01-01

    The signal transfer of a neuronal network is shaped by the local interactions between the excitatory principal cells and the inhibitory interneurons. We investigated with a simple lumped model how feedforward and feedback inhibition in.uence the steady-state network signal transfer. We analyze how

  9. Modulation of radiosensitivity by growth factors

    International Nuclear Information System (INIS)

    Paris, F.

    2013-01-01

    The full text of the publication follows. For the past 70 years, radiotherapy protocols were defined to target and kill cancer cells. New research developments showed that the tissue or tumor radiosensitivities might be directly modulated by its own microenvironment. Between all the micro-environmental cells, endothelial cells are playing a unique role due to the need of angio-genesis for tumor genesis and to the microvascular endothelial cell apoptosis involved in acute normal tissue and tumor radiosensitivities. Both endothelial behaviours may be controlled by specific growth factors secreted by tumor cells. Vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) are two cytokines involved in angio genesis and endothelial cell survival. Because radiation exposure develops opposite molecular and cellular responses by inhibiting proliferation and by enhancing apoptosis, inhibiting these cytokines has been proposed as a relevant strategy to improve radiotherapy efficiency. Drugs or antibody against VEGF, or other growth factors have been used with success to limit endothelial cell resistance, but also to transiently normalize of blood vessels to improve oxygen distribution into the tumor. However, better characterisation of the role of the cytokines will help to better improve the strategy of the use of their antagonists. We demonstrate that bFGF or sphingosin 1 phosphate (S1P), a lipid endothelial growth factor, protects endothelial cells from radiation stress by inhibiting the pre-mitotic apoptosis through enhancement of pro-survival molecular cascade, such as the Pi3K/AKT pathway, but not post-mitotic death. This discrepancy allowed a specific use of S1P as pharmacological drug protecting quiescent endothelial cells, present in normal tissue blood vessels, but not in proliferating angiogenic blood vessels, majority present in tumor blood vessel. In vivo studies are underway. (author)

  10. Hereditary syndromes with enhanced radiosensitivity

    International Nuclear Information System (INIS)

    Lohmann, D.

    2000-01-01

    Sensitivity to ionizing radiation is modified by heritable genetic factors. This is exemplified by heritable disorders that are characterized by predisposition to the development of neoplasms. Cells derived from patients with ataxia telangiectasia, Nijmegen breakage syndrome and ataxia telangiektasia-like disorder show a markedly changed reaction to exposure to ionizing radiation. Correspondingly, at least in patients with ataxia telangiectasia, an enhanced radiosensitivity that is of clinical importance has been observed. In addition to these recessive disorders, some autosomal dominant cancer predisposition syndromes are associated with increased radiosensitivity. As cells from these patients still have a normal allele (that is dominant over the mutant allele), the cellular phenotype is most often normal. Specifically, there is no overtly altered reaction in response to ionizing radiation. Nevertheless, two dominant cancer predisposition syndromes, namely hereditary retinoblastoma and naevoid basal cell carcinoma syndrome, are associated with a enhanced radiosensitivity as indicated by increased development of tumors following radiation therapy. (orig.) [de

  11. Hormonal status can modify radiosensitivity

    International Nuclear Information System (INIS)

    Ricoul, M.; Sabatier, L.; Dutrillaux, B.

    1997-01-01

    In preliminary experiments, we have demonstrated that pregnancy increases chromosome radiosensitivity in the mouse at the end of gestation. Blood obtained from women at various times of pregnancy was then exposed to ionizing radiations in vitro. By comparison to non pregnant women, an increase in chromosome breakages was observed in metaphases from lymphocytes. Immediately after delivery, this increase of radiosensitivity disappeared. In a prospective study, serial analyses showed a very strong correlation between the amount of pregnancy hormones, progesterone in particular, and the increase of radiosensitivity. Thus, pregnant women may have an increased sensitivity to ionizing radiation during the second half of their pregnancy and the risks of radiation exposure of pregnant women have to be considered not only n relation to the child, but also to their own hypersensitivity. (authors)

  12. Use of Mitochondria-Specific Dye MKT-077 as a Radiosensitizer to Preoperatively Treat Locally Advanced Breast Cancer

    National Research Council Canada - National Science Library

    Braun, Rodney D

    2007-01-01

    The major goal of this project is to determine if the rhodacyanine analog dye, MKT-077, can be used to inhibit breast cancer cell oxygen metabolism and raise tumor oxygen levels, thereby radiosensitizing the tumor...

  13. Use of Mitochondria-Specific Dye MKT-077 as a Radiosensitizer to Preoperatively Treat Locally Advanced Breast Cancer

    National Research Council Canada - National Science Library

    Braun, Rodney D

    2006-01-01

    The major goal of this project is to determine if the rhodacyanine analog dye, MKT-077, can be used to inhibit breast cancer cell oxygen metabolism and raise tumor oxygen levels, thereby radiosensitizing the tumor...

  14. Use of Mitochondria-Specific Dye MKT-077 as a Radiosensitizer to Preoperatively Treat Locally Advanced Breast Cancer

    National Research Council Canada - National Science Library

    Braun, Rodney D

    2008-01-01

    The major goal of this project is to determine if the rhodacyanine analog dye, MKT-077, can be used to inhibit breast cancer cell oxygen metabolism and raise tumor oxygen levels, thereby radiosensitizing the tumor...

  15. ATM-mediated Snail Serine 100 phosphorylation regulates cellular radiosensitivity

    International Nuclear Information System (INIS)

    Boohaker, Rebecca J.; Cui, Xiaoli; Stackhouse, Murray; Xu, Bo

    2013-01-01

    Purpose: Activation of the DNA damage responsive protein kinase ATM is a critical step for cellular survival in response to ionizing irradiation (IR). Direct targets of ATM regulating radiosensitivity remain to be fully investigated. We have recently reported that ATM phosphorylates the transcriptional repressor Snail on Serine 100. We aimed to further study the functional significance of ATM-mediated Snail phosphorylation in response to IR. Material and methods: We transfected vector-only, wild-type, the Serine 100 to alanine (S100A) or to glutamic acid (S100E) substitution of Snail into various cell lines. We assessed colony formation, γ-H2AX focus formation and the invasion index in the cells treated with or without IR. Results: We found that over-expression of the S100A mutant Snail in HeLa cells significantly increased radiosensitivity. Meanwhile the expression of S100E, a phospho-mimicking mutation, resulted in enhanced radio-resistance. Interestingly, S100E could rescue the radiosensitive phenotype in ATM-deficient cells. We also found that expression of S100E increased γ-H2AX focus formation and compromised inhibition of invasion in response to IR independent of cell survival. Conclusion: ATM-mediated Snail Serine 100 phosphorylation in response to IR plays an important part in the regulation of radiosensitivity

  16. Development of novel radiosensitizers for cancer therapy

    CERN Document Server

    Akamatsu, K

    2002-01-01

    The novel radiosensitizers for cancer therapy, which have some atoms with large X-ray absorption cross sections, were synthesized. The chemical and radiation (X-rays, W target, 100kVp) toxicities and the radiosensitivities to LS-180 human colon adenocarcinoma cells were also evaluated. 2,3,4,5,6-pentabromobenzylalcohol (PBBA) derivatives were not radiosensitive even around the maximum concentration. On the other hand, the hydrophilic sodium 2,4,6-triiodobenzoate (STIB) indicated meaningful radiosensitivity to the cells. Moreover, the membrane-specific radiosensitizers, cetyl fluorescein isthiocyanate (cetyl FITC), cetyl eosin isothiocyanate (cetyl br-FITC), cetyl erythrosin isothiocyanate (cetyl I-FITC), which aim for the membrane damage by X-ray photoabsorption on the target atoms, were localized in the plasma membrane. As the results of the colony formation assay, it was found that both cetyl FITC are similarly radiosensitive. In this report, we demonstrate the synthetic methods of the radiosensitizers, the...

  17. Radiosensitization of non-small cell lung cancer by kaempferol.

    Science.gov (United States)

    Kuo, Wei-Ting; Tsai, Yuan-Chung; Wu, His-Chin; Ho, Yung-Jen; Chen, Yueh-Sheng; Yao, Chen-Han; Yao, Chun-Hsu

    2015-11-01

    The aim of the present study was to determine whether kaempferol has a radiosensitization potential for lung cancer in vitro and in vivo. The in vitro radio-sensitization activity of kaempferol was elucidated in A-549 lung cancer cells by using an MTT (3-(4 5-dimethylthiazol-2-yl)-25-diphenyl-tetrazolium bromide) assay, cell cycle analysis and clonogenic assay. The in vivo activity was evaluated in the BALB/c nude mouse xenograft model of A-549 cells by hematoxylin and eosin staining and immunohistochemistry, and the tumor volume was recorded. Protein levels of the apoptotic pathway were detected by western blot analysis. Treatment with kaempferol inhibited the growth of A-549 cells through activation of apoptotic pathway. However, the same doses did not affect HFL1 normal lung cell growth. Kaempferol induced G2/M cell cycle arrest and the enhancement of radiation-induced death and clonogenic survival inhibition. The in vivo data showed that kaempferol increased tumor cell apoptosis and killing of radiation. In conclusion, the findings demonstrated that kaempferol increased tumor cell killing by radiation in vitro and in vivo through inhibition of the AKT/PI3K and ERK pathways and activation of the mitochondria apoptosis pathway. The results of the present study provided solid evidence that kaempferol is a safe and potential radiosensitizer.

  18. Identification of a radiosensitivity signature using integrative metaanalysis of published microarray data for NCI-60 cancer cells

    Directory of Open Access Journals (Sweden)

    Kim Han

    2012-07-01

    Full Text Available Abstract Background In the postgenome era, a prediction of response to treatment could lead to better dose selection for patients in radiotherapy. To identify a radiosensitive gene signature and elucidate related signaling pathways, four different microarray experiments were reanalyzed before radiotherapy. Results Radiosensitivity profiling data using clonogenic assay and gene expression profiling data from four published microarray platforms applied to NCI-60 cancer cell panel were used. The survival fraction at 2 Gy (SF2, range from 0 to 1 was calculated as a measure of radiosensitivity and a linear regression model was applied to identify genes or a gene set with a correlation between expression and radiosensitivity (SF2. Radiosensitivity signature genes were identified using significant analysis of microarrays (SAM and gene set analysis was performed using a global test using linear regression model. Using the radiation-related signaling pathway and identified genes, a genetic network was generated. According to SAM, 31 genes were identified as common to all the microarray platforms and therefore a common radiosensitivity signature. In gene set analysis, functions in the cell cycle, DNA replication, and cell junction, including adherence and gap junctions were related to radiosensitivity. The integrin, VEGF, MAPK, p53, JAK-STAT and Wnt signaling pathways were overrepresented in radiosensitivity. Significant genes including ACTN1, CCND1, HCLS1, ITGB5, PFN2, PTPRC, RAB13, and WAS, which are adhesion-related molecules that were identified by both SAM and gene set analysis, and showed interaction in the genetic network with the integrin signaling pathway. Conclusions Integration of four different microarray experiments and gene selection using gene set analysis discovered possible target genes and pathways relevant to radiosensitivity. Our results suggested that the identified genes are candidates for radiosensitivity biomarkers and that

  19. Predisposition to cancer and radiosensitivity

    International Nuclear Information System (INIS)

    Pichierri, P.; Franchitto, A.; Palitti, F.

    2000-01-01

    Many cancer-prone diseases have been shown to be radiosensitive. The radiosensitivity has been attributed to pitfalls in the mechanisms of repair of induced DNA lesions or to an impaired cell cycle checkpoint response. Although discrepancies exist in the results obtained by various authors on the radiosensitivity of individuals affected by the same disease, these can be attributed to the large variability observed already in the response to radiation of normal individuals. To date three test are commonly used to assess radiosensitivity in human cells: survival, micronucleus and G 2 chromosomal assay. The three tests may be performed using either fibroblasts or peripheral blood lymphocytes and all the three tests share large interindividual variability. In this regard a new approach to the G 2 chromosomal assay which takes into account the eventual differences in cell cycle progression among individuals has been developed. This new approach is based on the analysis of G 2 homogeneous cell populations. Cells irradiated are immediately challenged with medium containing bromodeoxyuridine (BrdU rd). Then cells are sampled at different post-irradiation times and BrdU rd incorporation detected on metaphases spread and the scoring is done only at time points showing similar incidence of labelled cells among the different donors. Using this approach it has been possible to reduce the interindividual variability of the G 2 chromosomal assay. (author)

  20. Increased chromosome radiosensitivity during pregnancy

    International Nuclear Information System (INIS)

    Ricoul, Michelle; Sabatier, Laure; Dutrillaux, Bernard

    1997-01-01

    It was necessary to consider the risks of exposure of pregnant women, not only in relation to the child, but also in relation to their own hypersensitivity. We have demonstrated that pregnancy increases radiosensitivity of chromosome in the mouse at the end of gestation. This is of importance since it may have implications on radioprotection of pregnant women and give experimental guidelines to the problems of hypersensitivity to drugs and cancer aggravation during pregnancy. Blood obtained from women at various times of pregnancy was exposed to ionizing radiations. By comparison to non-pregnant women, an increase in chromosome breakage was observed in metaphases from lymphocytes, after short-term culture in the presence of the serum of the same donor. Immediately after delivery, this increase in radiosensitivity disappeared. In a prospective study, serial analyses showed a very strong correlation between the amount of pregnancy hormones, progesterone in particular, and the increase in radiosensitivity. Pregnant women may have an increased sensitivity to ionizing radiation during the second half of their pregnancy. This study provides the first evidence in human that radiosensitivity may vary in relation to physiological conditions

  1. Effect of electroporation on radiosensitization with cisplatin in two cell lines with different chemo- and radiosensitivity

    International Nuclear Information System (INIS)

    Kranjc, S.; Cemazar, M.; Grosel, A.; Pipan, Z.; Sersa, G.

    2003-01-01

    Aim. Radiosensitization with cisplatin can be enhanced by electroporation of cells and tumours. The aim of this study was to extend our previous studies on two carcinoma tumour models with different chemo- and radiosensitivity in order to evaluate whether this treatment is effective also on less chemo- and radiosensitive tumour cells. Materials and methods. This in vitro study was performed on carcinoma SCK and EAT-E cells. The cytotoxicity of three-modality treatment consisting of cisplatin, electroporation and irradiation was determined by the clonogenic assay. Results. The radiosensitizing effect of cisplatin on the two cell lines was greatly enhanced by electroporation. By this combined treatment, less chemo and radiosensitive EAT-E cells were rendered as sensitive as more chemo and radiosensitive SCK cells. Conclusion. The enhancement of cisplatin-induced radiosensitization of cells by electroporation could be beneficially used in the treatment of intrinsically less chemo- and radiosensitive tumours. (author)

  2. Balance of excitation and inhibition determines 1/f power spectrum in neuronal networks.

    Science.gov (United States)

    Lombardi, F; Herrmann, H J; de Arcangelis, L

    2017-04-01

    The 1/f-like decay observed in the power spectrum of electro-physiological signals, along with scale-free statistics of the so-called neuronal avalanches, constitutes evidence of criticality in neuronal systems. Recent in vitro studies have shown that avalanche dynamics at criticality corresponds to some specific balance of excitation and inhibition, thus suggesting that this is a basic feature of the critical state of neuronal networks. In particular, a lack of inhibition significantly alters the temporal structure of the spontaneous avalanche activity and leads to an anomalous abundance of large avalanches. Here, we study the relationship between network inhibition and the scaling exponent β of the power spectral density (PSD) of avalanche activity in a neuronal network model inspired in Self-Organized Criticality. We find that this scaling exponent depends on the percentage of inhibitory synapses and tends to the value β = 1 for a percentage of about 30%. More specifically, β is close to 2, namely, Brownian noise, for purely excitatory networks and decreases towards values in the interval [1, 1.4] as the percentage of inhibitory synapses ranges between 20% and 30%, in agreement with experimental findings. These results indicate that the level of inhibition affects the frequency spectrum of resting brain activity and suggest the analysis of the PSD scaling behavior as a possible tool to study pathological conditions.

  3. Radiosensitization effects of nicotinamide on malignant and normal mouse tissue

    International Nuclear Information System (INIS)

    Jonsson, G.G.; Kjellen, E.; Pero, R.W.; Cameron, R.

    1985-01-01

    Inhibitors of the chromatin-associated enzyme adenosine diphosphate ribosyltransferase have been found to inhibit DNA strand rejoining and to potentiate lethality of DNA-damaging agents both in vivo and in vitro. The authors have in this work examined the radiosensitizing potential of one such inhibitor, nicotinamide, on tumor tissue by using transplanted C3H mouse mammary adenocarcinomas and on normal tissue in a tail-stunting experiment using BALB/cA mice. The data indicate a radiosensitizing effect of nicotinamide on tumor cells as well as on normal tissue. The data indicate a possible role of adenosine diphosphate ribosyltransferase inhibitors as a sensitizing agent in the radiotherapy of malignant tumors

  4. Radiosensitivity of garlic air bulbs

    International Nuclear Information System (INIS)

    Zhila, Eh.D.

    1975-01-01

    The paper presents data on the radiosensitivity of various sorts of garlic. It is shown that the frequency of chromosomal aberrations in the irradiated aerial bulbs of stemmed varieties of garlic is directly dependent upon the gmma-ray dose. With increasing dose the germination capacity and the viability of the plants diminishes. A dose of 750 r was found to be critical for the bulbs of the garlic varieties studied

  5. Radiosensitivity in ataxia-telangiectasia

    International Nuclear Information System (INIS)

    Lavin, M.F.; Khanna, K.K.; Watters, D.

    1998-01-01

    Full text: Radiosensitivity is a major hallmark of the human genetic disorder ataxia-telangiectasia. This hypersensitivity to ionizing radiation has been demonstrated in vitro after exposure of patients to therapeutic thought to be the major factor contculture. Clearly an understanding of the nature of the molecular defect in ataxia-telangiectasia will be of considerable assistance in delineating additional pathways that determine cellular radiosensitivity/radioresistance. Furthermore, since patients with this syndrome are also predisposed to developing a number of leukaemias and lymphomas the possible connection between radiosensitivity and cancer predisposition is of interest. Now that the gene (ATM) responsible for this genetic disease has been cloned and identified, progress is being made in determining the role of the ATM protein in mediating the effects of cellular exposure to ionizing radiation and other forms of redox stress. Proteins such as the product of the tumour suppressor gene p53 and the proto-oncogene c-Abl (a protein tyrosine kinase) have been shown to interact with ATM. Since several intermediate steps in both the p53 and c-Abl pathways, activated by ionizing radiation, are known it will be possible to map the position of ATM in these pathways and describe its mechanism of action. What are the clinical implications of understanding the molecular basis of the defect in ataxia-telangiectasia? As outlined above since radiosensitivity is a universal characteristic of A-T understanding the mechanism of action of ATM will provide additional information or radiation signalling in human cells. With this information it may be possible to sensitize tumour cells to radiation and thus increase the therapeutic benefit of radiotherapy. This might involve the use of small molecules that would interfere with the normal ATM controlled pathways and thus sensitize cells to radiation or alternatively it might involve the efficient introduction of ATM anti-sense c

  6. Radiosensitivity in ataxia-telangiectasia

    Energy Technology Data Exchange (ETDEWEB)

    Lavin, M.F. [Royal Brisbane Hospital, QLD (Australia). Queensland Institute of Medical Research and The Department of Surgery; Khanna, K.K.; Watters, D. [Royal Brisbane Hospital, QLD (Australia). Queensland Institute of Medical Research

    1998-12-31

    Full text: Radiosensitivity is a major hallmark of the human genetic disorder ataxia-telangiectasia. This hypersensitivity to ionizing radiation has been demonstrated in vitro after exposure of patients to therapeutic thought to be the major factor contculture. Clearly an understanding of the nature of the molecular defect in ataxia-telangiectasia will be of considerable assistance in delineating additional pathways that determine cellular radiosensitivity/radioresistance. Furthermore, since patients with this syndrome are also predisposed to developing a number of leukaemias and lymphomas the possible connection between radiosensitivity and cancer predisposition is of interest. Now that the gene (ATM) responsible for this genetic disease has been cloned and identified, progress is being made in determining the role of the ATM protein in mediating the effects of cellular exposure to ionizing radiation and other forms of redox stress. Proteins such as the product of the tumour suppressor gene p53 and the proto-oncogene c-Abl (a protein tyrosine kinase) have been shown to interact with ATM. Since several intermediate steps in both the p53 and c-Abl pathways, activated by ionizing radiation, are known it will be possible to map the position of ATM in these pathways and describe its mechanism of action. What are the clinical implications of understanding the molecular basis of the defect in ataxia-telangiectasia? As outlined above since radiosensitivity is a universal characteristic of A-T understanding the mechanism of action of ATM will provide additional information or radiation signalling in human cells. With this information it may be possible to sensitize tumour cells to radiation and thus increase the therapeutic benefit of radiotherapy. This might involve the use of small molecules that would interfere with the normal ATM controlled pathways and thus sensitize cells to radiation or alternatively it might involve the efficient introduction of ATM anti-sense c

  7. Mesoscopic segregation of excitation and inhibition in a brain network model.

    Directory of Open Access Journals (Sweden)

    Daniel Malagarriga

    2015-02-01

    Full Text Available Neurons in the brain are known to operate under a careful balance of excitation and inhibition, which maintains neural microcircuits within the proper operational range. How this balance is played out at the mesoscopic level of neuronal populations is, however, less clear. In order to address this issue, here we use a coupled neural mass model to study computationally the dynamics of a network of cortical macrocolumns operating in a partially synchronized, irregular regime. The topology of the network is heterogeneous, with a few of the nodes acting as connector hubs while the rest are relatively poorly connected. Our results show that in this type of mesoscopic network excitation and inhibition spontaneously segregate, with some columns acting mainly in an excitatory manner while some others have predominantly an inhibitory effect on their neighbors. We characterize the conditions under which this segregation arises, and relate the character of the different columns with their topological role within the network. In particular, we show that the connector hubs are preferentially inhibitory, the more so the larger the node's connectivity. These results suggest a potential mesoscale organization of the excitation-inhibition balance in brain networks.

  8. Mean-field analysis of orientation selectivity in inhibition-dominated networks of spiking neurons.

    Science.gov (United States)

    Sadeh, Sadra; Cardanobile, Stefano; Rotter, Stefan

    2014-01-01

    Mechanisms underlying the emergence of orientation selectivity in the primary visual cortex are highly debated. Here we study the contribution of inhibition-dominated random recurrent networks to orientation selectivity, and more generally to sensory processing. By simulating and analyzing large-scale networks of spiking neurons, we investigate tuning amplification and contrast invariance of orientation selectivity in these networks. In particular, we show how selective attenuation of the common mode and amplification of the modulation component take place in these networks. Selective attenuation of the baseline, which is governed by the exceptional eigenvalue of the connectivity matrix, removes the unspecific, redundant signal component and ensures the invariance of selectivity across different contrasts. Selective amplification of modulation, which is governed by the operating regime of the network and depends on the strength of coupling, amplifies the informative signal component and thus increases the signal-to-noise ratio. Here, we perform a mean-field analysis which accounts for this process.

  9. Studies on Drosophila radiosensitivity strains

    International Nuclear Information System (INIS)

    Varentsova, E.R.; Sharygin, V.I.; Khromykh, Yu.U.

    1985-01-01

    Fertility of radiosensitive mutant drosophila female strain rad (2) 201 61 after irradiation and frequency of dominant lethal mutations (DLM), induced by γ-radiation for 0-5 h and 5-7 days, are investigated. It is shown, that oocytes of the mutant strain are more radiosensitive as compared with cells of mongrel flies as to criterion of DLM appearance over the period of maturing. Early oocytes of stages 2-7 are the most sensitive, i.e. at the stages, corresponding to the manifestation of previously established recombination-defective properties of mutations rad (2) 201 61 . It is also sown, that doses of γ-rays, exceeding 10 Gy produce a strong sterilizing effect on mutant females due to destruction and resorption of egg chambers, irradiated at the stages of previtellogenetic growth of oocytes. In females, carrying mutation of radiosensitivity there is no direct correlation betwen sensitivity of oocytes proper to DLM induction and sensitivity of egg folleicles to resorbing effect of γ-rays. The ways of possible involvement of mutant locus studied into genetic processes in various specialized cells of drosophila

  10. The inherited basis of human radiosensitivity

    International Nuclear Information System (INIS)

    Gatti, R.A.

    2001-01-01

    Certain individuals cannot tolerate 'conventional' doses of radiation therapy. This is known to be true of patients with ataxia-telangiectasia and ligase IV deficiency. Although in vitro testing may not correlate completely with clinical radiosensitivity, fibroblasts and lymphoblasts from patients with both of these disorders have been clearly shown to be radiosensitive. Using a colony survival assay (CSA) to test lymphoblastoid cells after irradiation with 1 Gy, a variety of other genetic disorders have been identified as strong candidates for clinical radiosensitivity, such as Nijmegen breakage syndrome, Mre11 deficiency, and Fanconi's anemia. These data are presented and considered as a starting-point for the inherited basis of human radiosensitivity

  11. Orientation selectivity in inhibition-dominated networks of spiking neurons: effect of single neuron properties and network dynamics.

    Science.gov (United States)

    Sadeh, Sadra; Rotter, Stefan

    2015-01-01

    The neuronal mechanisms underlying the emergence of orientation selectivity in the primary visual cortex of mammals are still elusive. In rodents, visual neurons show highly selective responses to oriented stimuli, but neighboring neurons do not necessarily have similar preferences. Instead of a smooth map, one observes a salt-and-pepper organization of orientation selectivity. Modeling studies have recently confirmed that balanced random networks are indeed capable of amplifying weakly tuned inputs and generating highly selective output responses, even in absence of feature-selective recurrent connectivity. Here we seek to elucidate the neuronal mechanisms underlying this phenomenon by resorting to networks of integrate-and-fire neurons, which are amenable to analytic treatment. Specifically, in networks of perfect integrate-and-fire neurons, we observe that highly selective and contrast invariant output responses emerge, very similar to networks of leaky integrate-and-fire neurons. We then demonstrate that a theory based on mean firing rates and the detailed network topology predicts the output responses, and explains the mechanisms underlying the suppression of the common-mode, amplification of modulation, and contrast invariance. Increasing inhibition dominance in our networks makes the rectifying nonlinearity more prominent, which in turn adds some distortions to the otherwise essentially linear prediction. An extension of the linear theory can account for all the distortions, enabling us to compute the exact shape of every individual tuning curve in our networks. We show that this simple form of nonlinearity adds two important properties to orientation selectivity in the network, namely sharpening of tuning curves and extra suppression of the modulation. The theory can be further extended to account for the nonlinearity of the leaky model by replacing the rectifier by the appropriate smooth input-output transfer function. These results are robust and do not

  12. Orientation selectivity in inhibition-dominated networks of spiking neurons: effect of single neuron properties and network dynamics.

    Directory of Open Access Journals (Sweden)

    Sadra Sadeh

    2015-01-01

    Full Text Available The neuronal mechanisms underlying the emergence of orientation selectivity in the primary visual cortex of mammals are still elusive. In rodents, visual neurons show highly selective responses to oriented stimuli, but neighboring neurons do not necessarily have similar preferences. Instead of a smooth map, one observes a salt-and-pepper organization of orientation selectivity. Modeling studies have recently confirmed that balanced random networks are indeed capable of amplifying weakly tuned inputs and generating highly selective output responses, even in absence of feature-selective recurrent connectivity. Here we seek to elucidate the neuronal mechanisms underlying this phenomenon by resorting to networks of integrate-and-fire neurons, which are amenable to analytic treatment. Specifically, in networks of perfect integrate-and-fire neurons, we observe that highly selective and contrast invariant output responses emerge, very similar to networks of leaky integrate-and-fire neurons. We then demonstrate that a theory based on mean firing rates and the detailed network topology predicts the output responses, and explains the mechanisms underlying the suppression of the common-mode, amplification of modulation, and contrast invariance. Increasing inhibition dominance in our networks makes the rectifying nonlinearity more prominent, which in turn adds some distortions to the otherwise essentially linear prediction. An extension of the linear theory can account for all the distortions, enabling us to compute the exact shape of every individual tuning curve in our networks. We show that this simple form of nonlinearity adds two important properties to orientation selectivity in the network, namely sharpening of tuning curves and extra suppression of the modulation. The theory can be further extended to account for the nonlinearity of the leaky model by replacing the rectifier by the appropriate smooth input-output transfer function. These results are

  13. Impairment of GABA transporter GAT-1 terminates cortical recurrent network activity via enhanced phasic inhibition

    Directory of Open Access Journals (Sweden)

    Daniel Simon Razik

    2013-09-01

    Full Text Available In the central nervous system, GABA transporters (GATs very efficiently clear synaptically released GABA from the extracellular space, and thus exert a tight control on GABAergic inhibition. In neocortex, GABAergic inhibition is heavily recruited during recurrent phases of spontaneous action potential activity which alternate with neuronally quiet periods. Therefore, such activity should be quite sensitive to minute alterations of GAT function. Here, we explored the effects of a gradual impairment of GAT-1 and GAT-2/3 on spontaneous recurrent network activity – termed network bursts and silent periods – in organotypic slice cultures of rat neocortex. The GAT-1 specific antagonist NO-711 depressed activity already at nanomolar concentrations (IC50 for depression of spontaneous multiunit firing rate of 42 nM, reaching a level of 80% at 500-1000 nM. By contrast, the GAT-2/3 preferring antagonist SNAP-5114 had weaker and less consistent effects. Several lines of evidence pointed towards an enhancement of phasic GABAergic inhibition as the dominant activity-depressing mechanism: network bursts were drastically shortened, phasic GABAergic currents decayed slower, and neuronal excitability during ongoing activity was diminished. In silent periods, NO-711 had little effect on neuronal excitability or membrane resistance, quite in contrast to the effects of muscimol, a GABA mimetic which activates GABAA receptors tonically. Our results suggest that an enhancement of phasic GABAergic inhibition efficiently curtails cortical recurrent activity and may mediate antiepileptic effects of therapeutically relevant concentrations of GAT-1 antagonists.

  14. Effect of quercetin and 17-AAG on radiosensitivity of rat peripheral blood lymphocyte

    International Nuclear Information System (INIS)

    Chu Xuegang; Hong Chengjiao; Zhang Baoguo

    2012-01-01

    To investigate the effect of quercetin and 17-AAG on proliferation and on radiosensitivity of blood lymphocyte cells. CCK-8 assay is performed to evaluate the cytotoxicity of Quercetin on proliferation of blood lymphocyte cells. CCK-8 assay employed to observe its effects on the radiosensitivity of the cells quantified by calculating the sensitive enhancement ratio (SER). CCK-8 results showed that the inhibition of Quercetin on the cells was the dose-dependent and time-dependent, and the results of assay showed the inhibition of 17-AAG on blood lymphocyte cells was the dose-dependent and time-dependent. The study showed that Quercetin and 17-AAG have no effect on the radiosensitivity of the blood lymphocyte cells. (authors)

  15. Radiosensitivity study of cultured barley (hordeum vulgare)

    International Nuclear Information System (INIS)

    Wang Cailian; Shen Mei; Xu Gang; Zhao Kongnan; Chen Qiufang

    1991-07-01

    For studying the radioactivity, forty seven varieties of dormant barley seeds were irradiated with various doses (0 ∼ 400 Gy) of 137 Cs γ-rays. The results showed that the dose-effects relations of seedling growth inhibition could be fitted by an equation of F(D) = 1 - (1 - e -a 1 D ) N , and the dose-effects of cell-nucleus, the frequency of root tip cell with chromosome aberations and peroxidase isoenzyme band could be expressed by a linear regression equation Y = A + B · X. The radioactivity of naked barley was much higher than of covered barley. According to different radiosensitivities the varieties studied could be divided into five types i.e. extreme resistant, resistant, intermediate, sensitive, and extreme sensitive. The results also showed that there was close relationship between the DNA content of cell-nucleus, peroxidase isoenzyme zymogram and radioactivity. The radiosensitivty was proportional to the DNA content. The volume of cell-nucleus varied inversly as D 50 of nucleus volume and no obvious correlation with the D 50 of seedling growth inhibition

  16. Effect of retinoic acid on the radiosensitivity of normal human oral keratinocyte

    International Nuclear Information System (INIS)

    Lee, Jean; Heo, Min Suk; Lee, Sam Sun; Oh, Sung Ook; Choi, Soon Chul; Park, Tae Won; Lee, Sul Mi; Choi, Hang Moon

    2003-01-01

    To evaluate the effect of all-trans-retinotic acid (ATRA) on the radiosensitivity of normal human oral keratinocyte (NHOK). Relative cell survival fraction including SF2 (survival fraction at 2 Gy) was calculated on the basis of colony formation assay. Data were fitted to the linear-quadratic model to establish the survival curve and calculate α and β values. Using flow cytometry at 1, 2, 3, 4, and 5 days after exposure to 2 and 10 Gy irradiation, cell cycle arrest and apoptosis were analysed. To understand the molecular mechanism of the radiosensitization of ATRA on NHOK, proteins related with apoptosis and cell cycle arrest were investigated by Western blot analysis. Treatment with ATRA resulted in a significant decrease of SF2 value for NHOK from 0.63 to 0.27, and increased α and β value, indicating that ATRA increased radiosensitivity of NHOK. ATRA increased LDH significantly, but increasing irradiation dose decreased LDH, suggesting that the radiosensitizing effect of ATRA is not directly related with increasing cell necrosis by ATRA. ATRA did not induce appotosis but increased G2 arrest after 10 Gy irradiation, implying that the increased radiosensitivity of NHOK may be due to a decrease in mitosis caused by increasing G2 arrest. ATRA inhibited the reduction of p53 at 3 days after 10 Gy irradiation and increased p21 at 1 day after 10 Gy irradiation. Further study is required to determine the precise relationship between this effect and the radiosensitizing effect of ATRA. These results suggested that ATRA increase radiosensitivity by inhibiting mitosis caused by increasing G2 arrest.

  17. The HSP90 Inhibitor Ganetespib Radiosensitizes Human Lung Adenocarcinoma Cells

    Directory of Open Access Journals (Sweden)

    Roberto Gomez-Casal

    2015-05-01

    Full Text Available The molecular chaperone HSP90 is involved in stabilization and function of multiple client proteins, many of which represent important oncogenic drivers in NSCLC. Utilization of HSP90 inhibitors as radiosensitizing agents is a promising approach. The antitumor activity of ganetespib, HSP90 inhibitor, was evaluated in human lung adenocarcinoma (AC cells for its ability to potentiate the effects of IR treatment in both in vitro and in vivo. The cytotoxic effects of ganetespib included; G2/M cell cycle arrest, inhibition of DNA repair, apoptosis induction, and promotion of senescence. All of these antitumor effects were both concentration- and time-dependent. Both pretreatment and post-radiation treatment with ganetespib at low nanomolar concentrations induced radiosensitization in lung AC cells in vitro. Ganetespib may impart radiosensitization through multiple mechanisms: such as down regulation of the PI3K/Akt pathway; diminished DNA repair capacity and promotion of cellular senescence. In vivo, ganetespib reduced growth of T2821 tumor xenografts in mice and sensitized tumors to IR. Tumor irradiation led to dramatic upregulation of β-catenin expression in tumor tissues, an effect that was mitigated in T2821 xenografts when ganetespib was combined with IR treatments. These data highlight the promise of combining ganetespib with IR therapies in the treatment of AC lung tumors.

  18. Study of radiosensitization of chloroquine on esophageal cancer cell line

    International Nuclear Information System (INIS)

    Yuan Xiaoli; Li Tao; Huang Jianming; Zha Xiao; Deng Bifang; Lang Jinyi

    2014-01-01

    Objective: To investigate the possibility of chloroquine radiosensitization of esophageal cancer cell line TE-1 and its further mechanism. Methods: Effect of chloroquine on cell viability of TE-1 cells was determined by MTT method. Expression of LC3, Beclin-1 and formation of acidic vesicular organelles (AVOs) were determined by Western blot, and fluorescence staining with Lyso-Tracker Red DND-99, respectively. Clonogenic survival of TE-1 cells was examined by clonogenic forming assay. Results: Chloroquine showed dose-dependent inhibition of TE-1 cell growth, and its values of IC_5_0 and IC_1_0 were (72.33±5.28) and (15.42±3.33) μmol/L, respectively. The expression of Beclin-1 and LC3-II/I markedly increased in irradiated TE-1 cells. The addition of chloroquine with IC_1_0 concentration significantly reduced the fluorescence and intensity of AVOs accumulation in the cytoplasm of TE-1 cells. Clonogenic survival fraction decreased obviously in TE-1 cells with addition of chloroquine after radiation and the value of SERD0 was 1.439. Conclusions: Chloroquine could radiosensitize esophageal cancer cells by blocking autophagy-lysosomal pathway and be used as a potential radiosensitizing strategy. (authors)

  19. Radiosensitivity of lymphocytes among Filipinos: final report

    International Nuclear Information System (INIS)

    Medina, F.I.S.; Gregorio, J.S.; Aguilar, C.P.; Poblete, E.E.

    1996-01-01

    This report is about the studies on the radiosensitivity of Filipino lymphocytes to radiation that can elucidate on the potential of blood chromosomes as biological dosimeters. The objective of this study is to determine the radiosensitivity of lymphocytes among Filipinos and to establish the radiation-induced chromosome anomaly standard curve in lymphocytes for radiological dosimetry. 47 refs., 9 figs., 1 tab

  20. Radiosensitivity of mesothelioma cell lines

    International Nuclear Information System (INIS)

    Haekkinen, A.M.; Laasonen, A.; Linnainmaa, K.; Mattson, K.; Pyrhoenen, S.

    1996-01-01

    The present study was carried out in order to examine the radiosensitivity of malignant pleural mesothelioma cell lines. Cell kinetics, radiation-induced delay of the cell cycle and DNA ploidy of the cell lines were also determined. For comparison an HeLa and a human foetal fibroblast cell line were simultaneously explored. Six previously cytogenetically and histologically characterized mesothelioma tumor cell lines were applied. A rapid tiazolyl blue microtiter (MTT) assay was used to analyze radiosensitivity and cell kinetics and DNA ploidy of the cultured cells were determined by flow cytometry. The survival fraction after a dose of 2 Gy (SF2), parameters α and β of the linear quadratic model (LQ-model) and mean inactivation dose (D MID ) were also estimated. The DNA index of four cell lines equaled 1.0 and two cell lines equaled 1.5 and 1.6. Different mesothelioma cell lines showed a great variation in radiosensitivity. Mean survival fraction after a radiation dose of 2 Gy (SF2) was 0.60 and ranged from 0.36 to 0.81 and mean α value was 0.26 (range 0.48-0.083). The SF2 of the most sensitive diploid mesothelioma cell line was 0.36: Less than that of the foetal fibroblast cell line (0.49). The survival fractions (0.81 and 0.74) of the two most resistant cell lines, which also were aneuploid, were equal to that of the HeLa cell line (0.78). The α/β ratios of the most sensitive cell lines were almost an order of magnitude greater than those of the two most resistant cell lines. Radiation-induced delay of the most resistant aneuploid cell line was similar to that of HeLa cells but in the most sensitive (diploid cells) there was practically no entry into the G1 phase following the 2 Gy radiation dose during 36 h. (orig.)

  1. Periodic Forcing of Inhibition-Stabilized Networks: Nonlinear Resonances and Phase-Amplitude Coupling

    OpenAIRE

    Veltz, Romain; Sejnowski, Terrence J.

    2015-01-01

    International audience; Inhibition stabilized networks (ISNs) are neural architectures with strong positive feedback among pyramidal neurons balanced by strong negative feedback from in-hibitory interneurons, a circuit element found in the hippocampus and the primary vi-sual cortex. In their working regime, ISNs produce damped oscillations in the γ-range in response to inputs to the inhibitory population. In order to understand the proper-ties of interconnected ISNs, we investigated periodic ...

  2. Radiosensitivity of soft tissue sarcomas

    International Nuclear Information System (INIS)

    Hirano, Toru; Iwasaki, Katsuro; Suzuki, Ryohei; Monzen, Yoshio; Hombo, Zenichiro

    1989-01-01

    The correlation between the effectiveness of radiation therapy and the histology of soft tissue sarcomas was investigated. Of 31 cases with a soft tissue sarcoma of an extremity treated by conservative surgery and postoperative radiation of 3,000-6,000 cGy, local recurrence occurred in 12; 5 out of 7 synovial sarcomas, 4 of 9 MFH, one of 8 liposarcomas, none of 4 rhabdomyosarcomas and 2 of 3 others. As for the histological subtyping, the 31 soft tissue sarcomas were divided into spindle cell, pleomorphic cell, myxoid and round cell type, and recurrence rates were 75%, 33.3%, 16.7% and 0%, respectively. From the remarkable difference in recurrent rate, it was suggested that round cell and myxoid type of soft tissue sarcomas showed a high radiosensitivity compared to the spindle cell type with low sensitivity. Clarifying the degree of radiosensitivity is helpful in deciding on the management of limb salvage in soft tissue sarcomas of an extremity. (author)

  3. Activity-dependent switch of GABAergic inhibition into glutamatergic excitation in astrocyte-neuron networks.

    Science.gov (United States)

    Perea, Gertrudis; Gómez, Ricardo; Mederos, Sara; Covelo, Ana; Ballesteros, Jesús J; Schlosser, Laura; Hernández-Vivanco, Alicia; Martín-Fernández, Mario; Quintana, Ruth; Rayan, Abdelrahman; Díez, Adolfo; Fuenzalida, Marco; Agarwal, Amit; Bergles, Dwight E; Bettler, Bernhard; Manahan-Vaughan, Denise; Martín, Eduardo D; Kirchhoff, Frank; Araque, Alfonso

    2016-12-24

    Interneurons are critical for proper neural network function and can activate Ca 2+ signaling in astrocytes. However, the impact of the interneuron-astrocyte signaling into neuronal network operation remains unknown. Using the simplest hippocampal Astrocyte-Neuron network, i.e., GABAergic interneuron, pyramidal neuron, single CA3-CA1 glutamatergic synapse, and astrocytes, we found that interneuron-astrocyte signaling dynamically affected excitatory neurotransmission in an activity- and time-dependent manner, and determined the sign (inhibition vs potentiation) of the GABA-mediated effects. While synaptic inhibition was mediated by GABA A receptors, potentiation involved astrocyte GABA B receptors, astrocytic glutamate release, and presynaptic metabotropic glutamate receptors. Using conditional astrocyte-specific GABA B receptor ( Gabbr1 ) knockout mice, we confirmed the glial source of the interneuron-induced potentiation, and demonstrated the involvement of astrocytes in hippocampal theta and gamma oscillations in vivo. Therefore, astrocytes decode interneuron activity and transform inhibitory into excitatory signals, contributing to the emergence of novel network properties resulting from the interneuron-astrocyte interplay.

  4. Inhibition of the mitotic exit network in response to damaged telomeres.

    Directory of Open Access Journals (Sweden)

    Mauricio Valerio-Santiago

    Full Text Available When chromosomal DNA is damaged, progression through the cell cycle is halted to provide the cells with time to repair the genetic material before it is distributed between the mother and daughter cells. In Saccharomyces cerevisiae, this cell cycle arrest occurs at the G2/M transition. However, it is also necessary to restrain exit from mitosis by maintaining Bfa1-Bub2, the inhibitor of the Mitotic Exit Network (MEN, in an active state. While the role of Bfa1 and Bub2 in the inhibition of mitotic exit when the spindle is not properly aligned and the spindle position checkpoint is activated has been extensively studied, the mechanism by which these proteins prevent MEN function after DNA damage is still unclear. Here, we propose that the inhibition of the MEN is specifically required when telomeres are damaged but it is not necessary to face all types of chromosomal DNA damage, which is in agreement with previous data in mammals suggesting the existence of a putative telomere-specific DNA damage response that inhibits mitotic exit. Furthermore, we demonstrate that the mechanism of MEN inhibition when telomeres are damaged relies on the Rad53-dependent inhibition of Bfa1 phosphorylation by the Polo-like kinase Cdc5, establishing a new key role of this kinase in regulating cell cycle progression.

  5. Influence of the size of garlic propagules on radiosensitivity of clones

    International Nuclear Information System (INIS)

    Perez Talavera, S.; Acevedo, A.M.; Perez, A.

    1989-01-01

    The influence of the size of garlic propagules selected to be irradiated on the results of radiosensitivity was studied so as to determine the useful radiation doses for improvement. This was done using radio inhibition of the plant height index as criteria and the mahalanobis distance stadigrapher calculated among defined groups for the behaviour of cloves in reference to six radiation doses. Significative differences were found among dose-effect curves obtained when using big cloves and small cloves, in five garlic clones, as well as different behaviours of clone radiosensitivity when it was investigated using the two proposed variants

  6. The radio-sensitizing effects and mechanisms of artemisinin and its derivates

    Energy Technology Data Exchange (ETDEWEB)

    Jing, Zeng; Jianping, Cao; Saijun, Fan [School of Radiation Medicine and Public Health, Suzhou Univ., Suzhou (China)

    2008-10-15

    It has been proved that the antimalarial agent, Artemisinin and its derivates (such as artemether, arteether, artesunate, dihydroartemisinine, etc) boast powerful antitumor effects. Recently, researches have found that Artemisinin and its derivates can also enhance the radio-sensitivity of tumors through regulating cell cycle, creating cytotoxic effects induced by ROS, suppressing GSH activity and inhibiting the reparation of DNA damage etc. Moreover, they can reduce cell survival in a dose-dependent manner. This paper is paying more attention on the radio-sensitizing effects, characteristics and mechanisms of artemisinin and its derivates. (authors)

  7. The radio-sensitizing effects and mechanisms of artemisinin and its derivates

    International Nuclear Information System (INIS)

    Zeng Jing; Cao Jianping; Fan Saijun

    2008-01-01

    It has been proved that the antimalarial agent, Artemisinin and its derivates (such as artemether, arteether, artesunate, dihydroartemisinine, etc) boast powerful antitumor effects. Recently, researches have found that Artemisinin and its derivates can also enhance the radio-sensitivity of tumors through regulating cell cycle, creating cytotoxic effects induced by ROS, suppressing GSH activity and inhibiting the reparation of DNA damage etc. Moreover, they can reduce cell survival in a dose-dependent manner. This paper is paying more attention on the radio-sensitizing effects, characteristics and mechanisms of artemisinin and its derivates. (authors)

  8. Atomoxetine restores the response inhibition network in Parkinson’s disease

    Science.gov (United States)

    Rae, Charlotte L.; Nombela, Cristina; Rodríguez, Patricia Vázquez; Ye, Zheng; Hughes, Laura E.; Jones, P. Simon; Ham, Timothy; Rittman, Timothy; Coyle-Gilchrist, Ian; Regenthal, Ralf; Sahakian, Barbara J.; Barker, Roger A.; Robbins, Trevor W.

    2016-01-01

    Abstract Parkinson’s disease impairs the inhibition of responses, and whilst impulsivity is mild for some patients, severe impulse control disorders affect ∼10% of cases. Based on preclinical models we proposed that noradrenergic denervation contributes to the impairment of response inhibition, via changes in the prefrontal cortex and its subcortical connections. Previous work in Parkinson’s disease found that the selective noradrenaline reuptake inhibitor atomoxetine could improve response inhibition, gambling decisions and reflection impulsivity. Here we tested the hypotheses that atomoxetine can restore functional brain networks for response inhibition in Parkinson’s disease, and that both structural and functional connectivity determine the behavioural effect. In a randomized, double-blind placebo-controlled crossover study, 19 patients with mild-to-moderate idiopathic Parkinson’s disease underwent functional magnetic resonance imaging during a stop-signal task, while on their usual dopaminergic therapy. Patients received 40 mg atomoxetine or placebo, orally. This regimen anticipates that noradrenergic therapies for behavioural symptoms would be adjunctive to, not a replacement for, dopaminergic therapy. Twenty matched control participants provided normative data. Arterial spin labelling identified no significant changes in regional perfusion. We assessed functional interactions between key frontal and subcortical brain areas for response inhibition, by comparing 20 dynamic causal models of the response inhibition network, inverted to the functional magnetic resonance imaging data and compared using random effects model selection. We found that the normal interaction between pre-supplementary motor cortex and the inferior frontal gyrus was absent in Parkinson’s disease patients on placebo (despite dopaminergic therapy), but this connection was restored by atomoxetine. The behavioural change in response inhibition (improvement indicated by reduced

  9. Premotor spinal network with balanced excitation and inhibition during motor patterns has high resilience to structural division

    DEFF Research Database (Denmark)

    Petersen, Peter C; Vestergaard, Mikkel; Reveles Jensen, Kristian

    2014-01-01

    Direct measurements of synaptic inhibition (I) and excitation (E) to spinal motoneurons can provide an important insight into the organization of premotor networks. Such measurements of flexor motoneurons participating in motor patterns in turtles have recently demonstrated strong concurrent E...

  10. Normal cellular radiosensitivity in an adult Fanconi anaemia patient with marked clinical radiosensitivity

    International Nuclear Information System (INIS)

    Marcou, Yiola; D'Andrea, Andrew; Jeggo, Penelope A.; Plowman, Piers N.

    2001-01-01

    Background: Fanconi anaemia is a rare disease associated with cellular sensitivity to chemicals (e.g. mitomycin C and diepoxybutane); variable but mild cellular radiosensitivity has also been reported. Materials and methods: A 32-year-old patient with Fanconi anaemia and tonsillar carcinoma, treated by radiotherapy, was found to exhibit profound clinical radiosensitivity. Confluent, ulcerating oropharyngeal mucositis developed after a conventionally fractionated dose of 34 Gy and healing was incomplete by 2 months after cessation of therapy. Results: Cellular radiosensitivity assays and RPLD studies from this patient did not suggest any major detectable radiosensitivity. Conclusion: There is a discrepancy between the observed clinical radiosensitivity and the usual 'predictive' radiosensitivity assays in this patient with Fanconi anaemia

  11. Directional spike propagation in a recurrent network: dynamical firewall as anisotropic recurrent inhibition.

    Science.gov (United States)

    Samura, Toshikazu; Hayashi, Hatsuo

    2012-09-01

    It has been demonstrated that theta rhythm propagates along the septotemporal axis of the hippocampal CA1 of the rat running on a track, and it has been suggested that directional spike propagation in the hippocampal CA3 is reflected in CA1. In this paper, we show that directional spike propagation occurs in a recurrent network model in which neurons are connected locally and connection weights are modified through STDP. The recurrent network model consists of excitatory and inhibitory neurons, which are intrinsic bursting and fast spiking neurons developed by Izhikevich, respectively. The maximum length of connections from excitatory neurons is shorter in the horizontal direction than the vertical direction. Connections from inhibitory neurons have the same maximum length in both directions, and the maximum length of inhibitory connections is the same as that of excitatory connections in the vertical direction. When connection weights between excitatory neurons (E→E) were modified through STDP and those from excitatory neurons to inhibitory neurons (E→I) were constant, spikes propagated in the vertical direction as expected from the network structure. However, when E→I connection weights were modified through STDP, as well as E→E connection weights, spikes propagated in the horizontal direction against the above expectation. This paradoxical propagation was produced by strengthened E→I connections which shifted the timing of inhibition forward. When E→I connections are enhanced, the direction of effective inhibition changes from horizontal to vertical, as if a gate for spike propagation is opened in the horizontal direction and firewalls come out in the vertical direction. These results suggest that the advance of timing of inhibition caused by potentiation of E→I connections is influential in network activity and is an important element in determining the direction of spike propagation. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Radiosensitizing effects of 9401 on mice bearing H22 hepatoma

    International Nuclear Information System (INIS)

    Liu Xiaoqiu; Wang Qin; Zhou Zewei; Han Ying; Wang Dezhi; Shen Xiu

    2013-01-01

    Objective: To investigate the radiosensitizing effects of 9401 on mice bearing H22 hepatoma. Methods: Mouse model bearing H22 hepatoma cells were established. Mice were randomly divided into six groups, the control group,the radiation group and four treatment groups including 9401 at high, medium and low dosages and nicotinamide combined with radiation. After irradiated, the growth of tumor was observed, the time of tumor growth was recorded, the delay time of tumor growth and enhancement factor (EF) were calculated. After 28 days, the mice were killed, the tumors were stripped and inhibition rate was calculated. Results: Groups of 9401 combined with radiation could postpone tumor growth. The difference was statistically significant between 9401 groups at high, medium dosages combined with radiation and nicotinamide combined with radiation group (t=24.7 and 7.5, both P<0.01). Compared with radiation alone group, groups of 9401 combined with radiation had significant radiosensitizing effect. The enhancement factor of 9401 combined with radiation groups at high and medium dosages were 2.13 and 1.73 respectively, they were significant higher than nicotinamide combined with radiation group (t=2.26 and 9.04, both P<0.05). The inhibition rate of 9401 groups at high, medium and low dosages combined with radiation were 64.5%, 50.9% and 42.6% respectively. The inhibition rate of nicotinamide group combined radiation was 53.2%. The inhibition rate of 9401 at high dosage combined with radiation had significant difference with nicotinamide combined radiation (t =2.8, P<0.05). Nicotinamide combined with radiation group, 9401 combined with radiation groups could significant inhibit the growth of tumors compared with radiation alone group (t=5.7, 4.0 and 2.2, all P<0.05). Conclusion: 9401 can inhibit the tumor growth and the inhibition effect increases gradually with the drug dose increasing. It also has radiosensitizing effects on mice bearing H22 hepatoma and present broadly

  13. Radiogenomics: predicting clinical normal tissue radiosensitivity

    DEFF Research Database (Denmark)

    Alsner, Jan

    2006-01-01

    Studies on the genetic basis of normal tissue radiosensitivity, or  'radiogenomics', aims at predicting clinical radiosensitivity and optimize treatment from individual genetic profiles. Several studies have now reported links between variations in certain genes related to the biological response...... to radiation injury and risk of normal tissue morbidity in cancer patients treated with radiotherapy. However, after these initial association studies including few genes, we are still far from being able to predict clinical radiosensitivity on an individual level. Recent data from our own studies on risk...

  14. Thermal radiosensitization in heat- and radiation-sensitive mutants of CHO cells

    International Nuclear Information System (INIS)

    Kampinga, H.H.; Kanon, B.; Konings, A.W.T.; Stackhouse, M.A.; Bedford, J.S.

    1993-01-01

    In the current study, the extent of hyperthermic radiosensitization in a new γ-radiation-sensitive cell line, irs-20, recently isolated by Stackhouse and Bedford (1991) and a heat-sensitive mutant hs-36 (Harvey and Bedford 1988) was compared with the radiosensitization of their mutual parent CHO 10B12 cell line. The irs-20 and CHO 10B12 cells have comparable heat (43.5 o C) sensitivities, whereas hs-36 and CHO 10B12 show a similar sensitivity to γ- and X-rays. Radiosensitization due to pre-exposure to 43.5 o C heating of plateau phase cultures was found for all three cell lines, even after relatively mild heat treatment killing <20% of cells. Experiments using CHEF electrophoresis confirmed the dsb repair deficiency of the irs-20 cells (Stackhouse and Bedford 1992) and showed that heat inhibited dsb repair in all three cell lines. (Author)

  15. MiR-122 Induces Radiosensitization in Non-Small Cell Lung Cancer Cell Line

    Directory of Open Access Journals (Sweden)

    Debin Ma

    2015-09-01

    Full Text Available MiR-122 is a novel tumor suppresser and its expression induces cell cycle arrest, or apoptosis, and inhibits cell proliferation in multiple cancer cells, including non-small cell lung cancer (NSCLC cells. Radioresistance of cancer cell leads to the major drawback of radiotherapy for NSCLC and the induction of radiosensitization could be a useful strategy to fix this problem. The present work investigates the function of miR-122 in inducing radiosensitization in A549 cell, a type of NSCLC cells. MiR-122 induces the radiosensitization of A549 cells. MiR-122 also boosts the inhibitory activity of ionizing radiation (IR on cancer cell anchor-independent growth and invasion. Moreover, miR-122 reduced the expression of its targeted genes related to tumor-survival or cellular stress response. These results indicate that miR-122 would be a novel strategy for NSCLC radiation-therapy.

  16. Effect of Quercetin on radio-sensitivity of HeLa cells

    International Nuclear Information System (INIS)

    Wu Xiaofen; Hong Chengjiao; Guo Wenxiu; Pan Yanling; Zhang Baoguo

    2011-01-01

    In order to investigate the mechanism of Quercetin on radio-sensitivity of human Uterine Cervix Cancer HeLa cells, HeLa cells were cultured in different concentrations of Quercetin and different doses of irradiation. The clonogenic assay was used to observe the cell survival rate. The repair of DNA double-strand breaks and effect of Quercetin combination of radiation on the cell cycle were detected by flow cytometry. The results show that the radio-sensitivity of Quercetin on HeLa cells was obvious and the unrepaired DSBs after irradiation increased, but did not decrease G2/M cell cycle arrest. From this it can be inferred that the effect on HeLa cell radio-sensitivity may be related to the inhibition of the repair of DNA double-strand breaks induced by Quercetin, but it dose not reveal a significant relation with the cell cycle and G2/M arrest. (authors)

  17. Radiosensitivity of mesothelioma cell lines

    Energy Technology Data Exchange (ETDEWEB)

    Haekkinen, A.M. [Dept. of Oncology, Univ. Central Hospital, Helsinki (Finland); Laasonen, A. [Dept. of Pathology, Central Hospital of Etelae-Pohjanmaa, Seinaejoki (Finland); Linnainmaa, K. [Dept. of Industrial Hygiene and Toxicology, Inst. of Occupational Health, Helsinki (Finland); Mattson, K. [Dept. Pulmonary Medicine, Univ. Central Hospital, Helsinki (Finland); Pyrhoenen, S. [Dept. of Oncology, Univ. Central Hospital, Helsinki (Finland)

    1996-10-01

    The present study was carried out in order to examine the radiosensitivity of malignant pleural mesothelioma cell lines. Cell kinetics, radiation-induced delay of the cell cycle and DNA ploidy of the cell lines were also determined. For comparison an HeLa and a human foetal fibroblast cell line were simultaneously explored. Six previously cytogenetically and histologically characterized mesothelioma tumor cell lines were applied. A rapid tiazolyl blue microtiter (MTT) assay was used to analyze radiosensitivity and cell kinetics and DNA ploidy of the cultured cells were determined by flow cytometry. The survival fraction after a dose of 2 Gy (SF2), parameters {alpha} and {beta} of the linear quadratic model (LQ-model) and mean inactivation dose (D{sub MID}) were also estimated. The DNA index of four cell lines equaled 1.0 and two cell lines equaled 1.5 and 1.6. Different mesothelioma cell lines showed a great variation in radiosensitivity. Mean survival fraction after a radiation dose of 2 Gy (SF2) was 0.60 and ranged from 0.36 to 0.81 and mean {alpha} value was 0.26 (range 0.48-0.083). The SF2 of the most sensitive diploid mesothelioma cell line was 0.36: Less than that of the foetal fibroblast cell line (0.49). The survival fractions (0.81 and 0.74) of the two most resistant cell lines, which also were aneuploid, were equal to that of the HeLa cell line (0.78). The {alpha}/{beta} ratios of the most sensitive cell lines were almost an order of magnitude greater than those of the two most resistant cell lines. Radiation-induced delay of the most resistant aneuploid cell line was similar to that of HeLa cells but in the most sensitive (diploid cells) there was practically no entry into the G1 phase following the 2 Gy radiation dose during 36 h. (orig.).

  18. Sensory and cross-network contributions to response inhibition in patients with schizophrenia

    Directory of Open Access Journals (Sweden)

    Matthew J. Hoptman

    Full Text Available Patients with schizophrenia show response inhibition deficits equal to or greater than those seen in impulse-control disorders, and these deficits contribute to poor outcome. However, little is known about the circuit abnormalities underlying this impairment. To address this, we examined stop signal task performance in 21 patients with schizophrenia and 21 healthy controls using event related potential (ERP and resting state functional connectivity. Patients showed prolonged stop signal reaction time (SSRT and reduced N1, N2, and P3 amplitudes compared to controls. Across groups, P3 amplitudes were maximal after SSRT (i.e., after the time associated with the decision to stop occurred, suggesting that this component indexed response monitoring. Multiple regression analyses showed that longer SSRTs were independently related to 1 patient status, 2 reduced N1 amplitude on successful stop trials and 3 reduced anticorrelated resting state functional connectivity between visual and frontoparietal cortical networks. This study used a combined multimodal imaging approach to better understand the network abnormalities that underlie response inhibition in schizophrenia. It is the first of its kind to specifically assess the brain's resting state functional architecture in combination with behavioral and ERP methods to investigate response inhibition in schizophrenia. Keywords: EEG, Stop signal task, Impulsivity, Schizophrenia, Resting state functional connectivity

  19. Curcumin enhances the radiosensitivity of renal cancer cells by suppressing NF-κB signaling pathway.

    Science.gov (United States)

    Li, Gang; Wang, Ziming; Chong, Tie; Yang, Jie; Li, Hongliang; Chen, Haiwen

    2017-10-01

    The radiation resistance of renal cell carcinoma (RCC) remains the primary obstacle to improve patient survival. This study aimed to investigate the effects of curcumin on the radiosensitivity of RCC cells. Human RCC cell (ACHN) was exposed to irradiation (IR) and/or curcumin treatment. Cell viability, DNA repair, cell cycle, and apoptosis, were evaluated by MTT, immunofluoresence staining and flow cytometry. Moreover, ACHN cells were xenografted into nude mice and subjected to IR and/or curcumin treatment. The expression of NF-κB signaling related proteins in ACHN cells and xenografts was detected by western blot analysis. The results showed that curcumin significantly increased radiosensitivity of ACHN cells by inhibiting the cell proliferation and DNA damage repair, causing cell cycle arrest at G2/M phase, inducing apoptosis in vitro, and suppressing the growth of xenografts in vivo. In addition, curcumin enhanced radiosensitivity was through markedly inhibiting IR-induced NF-κB signaling by modulating the related protein expressions including NF-κBP65, I-κB, VEGF, COX2, and Bcl-2 in ACHN cells, which was further strengthened by NF-κB inhibitor PDTC treatment. Thus, curcumin may confer radiosensitivity on RCC via inhibition of NF-κB activation and its downstream regulars, suggesting the potential application of curcumin as an adjuvant in radiotherapy of RCC. Copyright © 2017. Published by Elsevier Masson SAS.

  20. Local excitation-inhibition ratio for synfire chain propagation in feed-forward neuronal networks

    Science.gov (United States)

    Guo, Xinmeng; Yu, Haitao; Wang, Jiang; Liu, Jing; Cao, Yibin; Deng, Bin

    2017-09-01

    A leading hypothesis holds that spiking activity propagates along neuronal sub-populations which are connected in a feed-forward manner, and the propagation efficiency would be affected by the dynamics of sub-populations. In this paper, how the interaction between local excitation and inhibition effects on synfire chain propagation in feed-forward network (FFN) is investigated. The simulation results show that there is an appropriate excitation-inhibition (EI) ratio maximizing the performance of synfire chain propagation. The optimal EI ratio can significantly enhance the selectivity of FFN to synchronous signals, which thereby increases the stability to background noise. Moreover, the effect of network topology on synfire chain propagation is also investigated. It is found that synfire chain propagation can be maximized by an optimal interlayer linking probability. We also find that external noise is detrimental to synchrony propagation by inducing spiking jitter. The results presented in this paper may provide insights into the effects of network dynamics on neuronal computations.

  1. Radiosensitization and relative mechanisms of vanillin derivative BVAN08 on human glioma U-251 cells

    International Nuclear Information System (INIS)

    Wang Shubin; Zhang Bo; Sun Weijian; Wang Yu; Liu Xiaodan; Xu Qinzhi; Zhou Pingkun

    2010-01-01

    Objective: To provide more convincing evidences and experimental data for exploring vanillin derivative BVAN08, 6-bromine-5-hydroxy-4-methoxy-benzaldehyde, as a new anticancer drug, and to investigate the effect on the growth, radiosensitization of human glioma cell line U-251 and the relative mechanism. Methods: The effect of BVAN08 on cell proliferation of U-251 and radiosensitivity to 60 Co γ-rays (irradiation dose rate 2.3 Gy/min) were analyzed with MTT and colony-forming ability assay. Change in cellular morphology was observed by using light microscope. Change in cell cycle and apoptosis was detected with flow cytometry. The autophagy was observed by using TEM (irradiation dose rate is transmission electron microscope). DNA-PKcs protein level was detected through Western blot analysis. Results: BVAN08 exhibited a dose- and time-dependent inhibition on the proliferation of U-251 cells during the concentration range of 10-100 mol/L (t=1.83-3.07, P 50 at 48 h and 72 h after administration with BVAN08 were 55.3 and 52.7 mol/L, respectively. Obvious G 2 /M arrest was induced in U-251 cells after 4 h administration with BVAN08, and reached peck at 12 h. The G 2 /M population reached 63.3% in U-251 cells after 12 h administration of 60 μmol/L BVAN08 and kept increasing with the time, while both apoptosis and autophagic cell death were induced. The most effective radiosensitization time for BVAN08 treatment was 12 h before irradiation. The enhancement ratio of radiosensitivity was 3.14 for 20 μmol/L of BVAN08 12 h before 2 Gy irradiation. Conclusions: BVAN08 can induce apoptosis as radiosensitizing effect might be associated with the induction of G 2 /M arrest and inhibition of DNA-PKcs expression. BVAN08 seemed to be a promising radiosensitizing anticancer drug. (authors)

  2. Joint immobilization inhibits spontaneous hyaline cartilage regeneration induced by a novel double-network gel implantation.

    Science.gov (United States)

    Arakaki, Kazunobu; Kitamura, Nobuto; Kurokawa, Takayuki; Onodera, Shin; Kanaya, Fuminori; Gong, Jian-Ping; Yasuda, Kazunori

    2011-02-01

    We have recently discovered that spontaneous hyaline cartilage regeneration can be induced in an osteochondral defect in the rabbit, when we implant a novel double-network (DN) gel plug at the bottom of the defect. To clarify whether joint immobilization inhibits the spontaneous hyaline cartilage regeneration, we conducted this study with 20 rabbits. At 4 or 12 weeks after surgery, the defect in the mobile knees was filled with a sufficient volume of the hyaline cartilage tissue rich in proteoglycan and type-2 collagen, while no cartilage tissues were observed in the defect in the immobilized knees. Type-2 collagen, Aggrecan, and SOX9 mRNAs were expressed only in the mobile knees at each period. This study demonstrated that joint immobilization significantly inhibits the spontaneous hyaline cartilage regeneration induced by the DN gel implantation. This fact suggested that the mechanical environment is one of the significant factors to induce this phenomenon.

  3. The inherited basis of human radiosensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Gatti, R.A. [Univ. of California, School of Medicine, Los Angeles, CA (United States). Experimental Pathology

    2001-11-01

    Certain individuals cannot tolerate 'conventional' doses of radiation therapy. This is known to be true of patients with ataxia-telangiectasia and ligase IV deficiency. Although in vitro testing may not correlate completely with clinical radiosensitivity, fibroblasts and lymphoblasts from patients with both of these disorders have been clearly shown to be radiosensitive. Using a colony survival assay (CSA) to test lymphoblastoid cells after irradiation with 1 Gy, a variety of other genetic disorders have been identified as strong candidates for clinical radiosensitivity, such as Nijmegen breakage syndrome, Mre11 deficiency, and Fanconi's anemia. These data are presented and considered as a starting-point for the inherited basis of human radiosensitivity.

  4. Comparative radiosensitivity in the class insecta

    International Nuclear Information System (INIS)

    Willard, W.K.; Cherry, D.S.

    1975-01-01

    A 'radiosensitivity index' (LT 50 /mean longevity) was correlated with the mean longevity and dry weight of 37 insect species (both sexes of 12 species) representing eight orders. Curvilinear regression analysis relating radiosensitivity to mean longevity and mean dry weight indicated that 46.3% of the observed variation could be attributed to longevity and 32.6% to the dry weight of the species. In general, large long-lived adults were more radiosensitive than small short-lived adults. Correlation of the phylogeny of insect orders and order groupings with the radio-sensitivity index was found to be poor. However, when the index was related to longevity, there was a tendency for species comprising the major orders investigated to occur in groups along the predicted curve. (author)

  5. In vitro and in vivo study of a nanoliposomal cisplatin as a radiosensitizer

    Directory of Open Access Journals (Sweden)

    Xiaomeng Zhang

    2011-02-01

    Full Text Available Xiaomeng Zhang1*, Huanjun Yang1*, Ke Gu1, Jian Chen2, Mengjie Rui2, Guo-Liang Jiang11Departments of Radiation Oncology, Fudan University Shanghai Cancer Center; Department of Oncology, Shanghai Medical College,Fudan University,Shanghai, People’s Republic of China; 2School of Pharmacy, Shanghai Jiao Tong University, Shanghai, People’s Republic of China; *Xiaomeng Zhang and Huanjun Yang share the first authorshipObjective: To investigate the in vitro and in vivo radiosensitization effect of an institutionally designed nanoliposome encapsulated cisplatin (NLE-CDDP.Materials and methods: NLE-CDDP was developed by our institute. In vitro radiosensitization of NLE-CDDP was evaluated by colony forming assay in A549 cells. In vivo radiosensitization was studied with tumor growth delay (TGD in Lewis lung carcinoma. The radiosensitization for normal tissue was investigated by jejunal crypt survival. The radiosensitization studies were carried out with a 72 h interval between drug administration and irradiation. The mice were treated with 6 mg/kg of NLE-CDDP or CDDP followed by single doses of 2 Gy, 6 Gy, 16 Gy, and 28 Gy. Sensitization enhancement ratio (SER was calculated by D0s of cell survival curves for A549 cells, doses needed to yield TGD of 20 days in Lewis lung carcinoma, or D0s of survival curves in crypt cells in radiation alone and radiation plus drug groups.Results: Our NLE-CDDP could inhibit A549 cells in vitro with half maximal inhibitory concentration of 1.12 µg/mL, and its toxicity was 2.35 times that observed in CDDP. For in vitro studies of A549 cells, SERs of NLE-CDDP and CDDP were 1.40 and 1.14, respectively, when combined with irradiation. For in vivo studies of Lewis lung carcinoma, the strongest radiosensitization was found in the 72 h interval between NLE-CDDP and irradiation. When given 72 h prior to irradiation, NLE-CDDP yielded higher radiosensitization than CDDP (SER of 4.92 vs 3.21 and slightly increased injury in jejunal

  6. Integrin inhibitor (Cilengitide) as radiosensitization strategy for malignant tumors

    International Nuclear Information System (INIS)

    Silva, Felipe Henrique de Souza

    2017-01-01

    Radiotherapy is effective in tumor control, but several tumors have molecular characteristics that lead to radioresistance and possible posttreatment recurrence. Many tumors have overexpression of integrin receptors. Integrins play a central role in growth, motility, regulation of adhesion and survival, leading to increased proliferation, invasion and metastasis of tumors, making these receptors excellent targets for the development of new therapies. Studies have shown that inhibiting the interaction of matrix proteins with integrin receptors may increase the cytotoxic effect of ionizing radiation by demonstrating the radiosensitizing potential of combination therapy in tumoral lines. Cilengitide an inhibitor of integrins receptors α Vβ3 and αVβ5 stands out for its great antitumor potential against gliomas. Thus, the combination of ionizing radiation with cilengitide is an alternative therapeutic strategy. However, the effect of this combination is little studied in Glioblastomas (U87 and T98) and not studied in melanoma (UACC). The objective of this study was to evaluate the radiosensitising potential of the RGD molecule cilengitida by means of the combined treatment with gamma radiation in different tumor lines, as well as to compare the effect of this combination therapy with cisplatin, a molecule already used in clinical practice. Our panel of tumor cell lines was composed of U87 (wild-type p53 malignant glioblastoma) T98 (malignant glioblastoma mutant p53), MCF7 (mammary carcinoma) and UACC (melanoma). The radiosensitizer effect of cilengitide was evaluated by the quantification of metabolic cell viability through the MTT assay. Inhibition of colony formation was investigated in clonogenicity assays. The flow cytometer was used to investigate cell cycle distribution and the type of cell death induced. We observed that in all cell lines examined, cilengitida promoted detachment, metabolic alterations and reduction of proliferation, as well as alteration of

  7. Andrographolide radiosensitizes human esophageal cancer cell line ECA109 to radiation in vitro.

    Science.gov (United States)

    Wang, Z-M; Kang, Y-H; Yang, X; Wang, J-F; Zhang, Q; Yang, B-X; Zhao, K-L; Xu, L-P; Yang, L-P; Ma, J-X; Huang, G-H; Cai, J; Sun, X-C

    2016-01-01

    To explore the radiosensitivity of andrographolide on esophageal cancer cell line ECA109. The inhibition effects of andrographolide were measured using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium (MTT) assay. Clonogenic survival assay was used to evaluate the effects of andrographolide on the radiosensitivity of esophageal cancer cells. Immunofluorescence was employed to examine Bax expression. The changes in cell cycle distribution and apoptosis were assayed using flow cytometry. The expression of NF-κb/Cleaved-Caspase3/Bax/Bcl-2 was measured using Western blot analysis. DNA damage was detected via γ-H2AX foci counting. With a clear dose and time effects, andrographolide was found to inhibit the proliferation of esophageal cell line ECA109. The results of the clonogenic survival assay show that andrographolide could markedly enhance radiosensitivity (P Andrographolide caused a dose-dependent increase in Cleaved-Caspase3/Bax protein expression and a decrease in Bcl-2/NF-κb expression. Apoptosis in andrographolide-treated ECA-109 increased significantly compared with the apoptosis in the simple drug and radiation combined with drug groups (P andrographolide combined with radiation group increased the number of DNA double chain breaks. Andrographolide can increase the radiosensitivity of esophageal cell line ECA109. This result may be associated with the decrease in the NF-κb level and the induced apoptosis of esophageal cancer cells. © 2014 International Society for Diseases of the Esophagus.

  8. 53BP1 loss suppresses the radiosensitizing effect of icotinib hydrochloride in colorectal cancer cells.

    Science.gov (United States)

    Huang, Ai; Yao, Jing; Liu, Tao; Lin, Zhenyu; Zhang, Sheng; Zhang, Tao; Ma, Hong

    2018-04-01

    This study aimed to investigate the influence of the expression of P53-binding protein 1 (53BP1), a key component in DNA damage repair pathways, on the radiosensitizing effect of icotinib hydrochloride in colorectal cancer and to elucidate the mechanisms underlying this influence. Real-time RT-PCR and Western blotting were performed to verify the gene-knockout effect of 53BP1 small hairpin RNA (ShRNA), and colony formation assay was employed to investigate the influence of 53BP1 downregulation on the radiosensitizing effect of icotinib hydrochloride in HCT116 cells. Cell apoptosis, cell cycle distributions, and histone H2AX (γ-H2AX) fluorescence foci after 53BP1 knockdown were evaluated. Relative protein expression in the ataxia telangiectasia mutated kinase (ATM)-checkpoint kinase-2 (CHK2)-P53 pathway was measured by Western blot analysis to unravel the molecular mechanisms linking the pathway to the above phenomena. Icotinib hydrochloride increased the radiosensitivity of HCT116 cells; however, this effect was suppressed by the downregulation of 53BP1 expression, a change that inhibited cell apoptosis, increased the percentage of HCT116 cells arrested in S-phase and inhibited the protein expression of key molecules in the ATM-CHK2-P53 apoptotic pathway. Our studies confirmed that the loss of 53BP1 serves as a negative regulator of the radiosensitizing effect of icotinib in part by suppressing the ATM-CHK2-P53 apoptotic pathway.

  9. Effect of allicin on the radiosensitivity of human pancreatic carcinoma BXPC3 cells

    International Nuclear Information System (INIS)

    Ma Hongbing; Di Zhengli; He Na; Wen Jiao; Ke Yue

    2014-01-01

    Objective: To study the effect of allicin on the growth and radiosensitivity of human pancreatic carcinoma BXPC3 cells. Methods: BXPC3 cells were exposed to X-rays in the presence or absence of allicin. Cell proliferation was measured by MTT assay. Cell cycle distribution and apoptosis were detected by flow cytometry assay. Cell radiosensitivity and the influence of allicin on it was evaluated by colony formation assay. The expressions of Bax and Bcl-2 proteins were assayed by RT-PCR and Western blot. Results: IC 50 values of allicin on cell growth were 76.24, 58.34 and 43.58 μmol/L under 12, 24 and 48 h treatment, respectively. Treatment of cells with allicin obviously inhibited cell growth after irradiation and hence increased radiosensitivity (t = 2.74, P < 0.05). This treament also enhanced radiation-induced cell cycle arrest at G 2 /M phase (t = 11.41, P < 0.05), apoptosis induction (t = 12.36, P < 0.05), and Bax expression (t = 4.83, P < 0.05), but it decreased Bcl-2 expression (t = 3.69, P < 0.05). Conclusions: Allicin could inhibit cell growth, induce cell cycle arrest and apoptosis via Bax/Bcl-2 pathway and hence increases radiosensitivity of BXPC3 cells. (authors)

  10. Activating PTEN by COX-2 inhibitors antagonizes radiation-induced AKT activation contributing to radiosensitization

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Zhen [Central Laboratory, Peking University School and Hospital of Stomatology, 22 Zhongguancun Avenue South, Haidian District, Beijing 100081 (China); Department of Oral & Maxillofacial Surgery, Peking University School and Hospital of Stomatology, 22 Zhongguancun Avenue South, Haidian District, Beijing 100081 (China); Gan, Ye-Hua, E-mail: kqyehuagan@bjmu.edu.cn [Central Laboratory, Peking University School and Hospital of Stomatology, 22 Zhongguancun Avenue South, Haidian District, Beijing 100081 (China); Department of Oral & Maxillofacial Surgery, Peking University School and Hospital of Stomatology, 22 Zhongguancun Avenue South, Haidian District, Beijing 100081 (China)

    2015-05-01

    Radiotherapy is still one of the most effective nonsurgical treatments for many tumors. However, radioresistance remains a major impediment to radiotherapy. Although COX-2 inhibitors can induce radiosensitization, the underlying mechanism is not fully understood. In this study, we showed that COX-2 selective inhibitor celecoxib enhanced the radiation-induced inhibition of cell proliferation and apoptosis in HeLa and SACC-83 cells. Treatment with celecoxib alone dephosphorylated phosphatase and tensin homolog deleted on chromosome ten (PTEN), promoted PTEN membrane translocation or activation, and correspondingly dephosphorylated or inactivated protein kinase B (AKT). By contrast, treatment with radiation alone increased PTEN phosphorylation, inhibited PTEN membrane translocation and correspondingly activated AKT in the two cell lines. However, treatment with celecoxib or another COX-2 selective inhibitor (valdecoxib) completely blocked radiation-induced increase of PTEN phosphorylation, rescued radiation-induced decrease in PTEN membrane translocation, and correspondingly inactivated AKT. Moreover, celecoxib could also upregulate PTEN protein expression by downregulating Sp1 expression, thereby leading to the activation of PTEN transcription. Our results suggested that COX-2 inhibitors could enhance radiosensitization at least partially by activating PTEN to antagonize radiation-induced AKT activation. - Highlights: • COX-2 inhibitor, celecoxib, could enhance radiosensitization. • Radiation induced PTEN inactivation (phosphorylation) and AKT activation. • COX-2 inhibitor induced PTEN expression and activation, and inactivated AKT. • COX-2 inhibitor enhanced radiosensitization through activating PTEN.

  11. Dynamic telomerase gene suppression via network effects of GSK3 inhibition.

    Directory of Open Access Journals (Sweden)

    Alan E Bilsland

    2009-07-01

    Full Text Available Telomerase controls telomere homeostasis and cell immortality and is a promising anti-cancer target, but few small molecule telomerase inhibitors have been developed. Reactivated transcription of the catalytic subunit hTERT in cancer cells controls telomerase expression. Better understanding of upstream pathways is critical for effective anti-telomerase therapeutics and may reveal new targets to inhibit hTERT expression.In a focused promoter screen, several GSK3 inhibitors suppressed hTERT reporter activity. GSK3 inhibition using 6-bromoindirubin-3'-oxime suppressed hTERT expression, telomerase activity and telomere length in several cancer cell lines and growth and hTERT expression in ovarian cancer xenografts. Microarray analysis, network modelling and oligonucleotide binding assays suggested that multiple transcription factors were affected. Extensive remodelling involving Sp1, STAT3, c-Myc, NFkappaB, and p53 occurred at the endogenous hTERT promoter. RNAi screening of the hTERT promoter revealed multiple kinase genes which affect the hTERT promoter, potentially acting through these factors. Prolonged inhibitor treatments caused dynamic expression both of hTERT and of c-Jun, p53, STAT3, AR and c-Myc.Our results indicate that GSK3 activates hTERT expression in cancer cells and contributes to telomere length homeostasis. GSK3 inhibition is a clinical strategy for several chronic diseases. These results imply that it may also be useful in cancer therapy. However, the complex network effects we show here have implications for either setting.

  12. Arbuscular-mycorrhizal networks inhibit Eucalyptus tetrodonta seedlings in rain forest soil microcosms.

    Directory of Open Access Journals (Sweden)

    David P Janos

    Full Text Available Eucalyptus tetrodonta, a co-dominant tree species of tropical, northern Australian savannas, does not invade adjacent monsoon rain forest unless the forest is burnt intensely. Such facilitation by fire of seedling establishment is known as the "ashbed effect." Because the ashbed effect might involve disruption of common mycorrhizal networks, we hypothesized that in the absence of fire, intact rain forest arbuscular mycorrhizal (AM networks inhibit E. tetrodonta seedlings. Although arbuscular mycorrhizas predominate in the rain forest, common tree species of the northern Australian savannas (including adult E. tetrodonta host ectomycorrhizas. To test our hypothesis, we grew E. tetrodonta and Ceiba pentandra (an AM-responsive species used to confirm treatments separately in microcosms of ambient or methyl-bromide fumigated rain forest soil with or without severing potential mycorrhizal fungus connections to an AM nurse plant, Litsea glutinosa. As expected, C. pentandra formed mycorrhizas in all treatments but had the most root colonization and grew fastest in ambient soil. E. tetrodonta seedlings also formed AM in all treatments, but severing hyphae in fumigated soil produced the least colonization and the best growth. Three of ten E. tetrodonta seedlings in ambient soil with intact network hyphae died. Because foliar chlorosis was symptomatic of iron deficiency, after 130 days we began to fertilize half the E. tetrodonta seedlings in ambient soil with an iron solution. Iron fertilization completely remedied chlorosis and stimulated leaf growth. Our microcosm results suggest that in intact rain forest, common AM networks mediate belowground competition and AM fungi may exacerbate iron deficiency, thereby enhancing resistance to E. tetrodonta invasion. Common AM networks-previously unrecognized as contributors to the ashbed effect-probably help to maintain the rain forest-savanna boundary.

  13. Radiosensitivity in cultured human fibroblasts

    International Nuclear Information System (INIS)

    Cox, R.; Masson, W.K.

    1980-01-01

    Caution is urged in the use of freshly isolated cultures of human diploid fibroblasts for quantitative studies of radiosensitivity. The distribution of x ray sensitivities of 'normal' human fibroblast cultures of foetal origin (10 subjects, skin or lung biopsy) and post-foetal origin (34 subjects, skin biopsy) are compared with the distribution in 12 patients with ataxia telangiectasia (probability of including any one of these in a normal post-foetal distribution is 0.01%). Cultures from nominally normal subjects showed a broad distribution of D 0 range of 98 +- 160 rad and assuming normal distribution, a mean +- one standard deviation of 122 +- 17 rad. Mean D 0 values for foetal origin cultures were 117 +- 12; values for post-foetal cultures D 0 were 124 +- 18. No systematic variation in D 0 was observed for age of donor, number of cell divisions in culture or for cloning efficiency. For ataxia telangiectasia D 0 values were 46 +- 7 rad. (U.K.)

  14. DNA damage repair and radiosensitivity

    International Nuclear Information System (INIS)

    Suzuki, Norio

    2003-01-01

    Tailored treatment is not new in radiotherapy; it has been the major subject for the last 20-30 years. Radiation responses and RBE (relative biological effectiveness) depend on assay systems, endpoints, type of tissues and tumors, radiation quality, dose rate, dose fractionation, physiological and environmental factors etc, Latent times to develop damages also differ among tissues and endpoints depending on doses and radiation quality. Recent progress in clarification of radiation induced cell death, especially of apoptotic cell death, is quite important for understanding radiosensitivity of tumor cure process as well as of tumorigenesis. Apoptotic cell death as well as dormant cells had been unaccounted and missed into a part of reproductive cell death. Another area of major progress has been made in clarifying repair mechanisms of radiation damage, i.e., non-homologous end joining (NHEJ) and homologous recombinational repair (HRR). New approaches and developments such as cDNA or protein micro arrays and so called informatics in addition to basic molecular biological analysis are expected to aid identifying molecules and their roles in signal transduction pathways, which are multi-factorial and interactive each other being involved in radiation responses. (authors)

  15. Effect of hypothermia on radiosensitization

    International Nuclear Information System (INIS)

    Nias, A.H.W.; Perry, P.; Photiou, A.; Reghebi, K.

    1986-01-01

    The blood supply and oxygen tension have been measured in C3H mouse mammary tumours under hypothermia and hyperbaric oxygen, and the enhancement of radiosensitivity by hyperbaric oxygen has been estimated in mice irradiated at different temperatures with and without anaesthesia. Measurement of xenon-133 clearance showed that the blood supply of a tumour tended to increase when anaesthetized mice became hypothermic. Oxygen cathode data showed that the oxygen tension tended to be relatively higher in tumours and lower in subcutaneous tissue when mice exposed to hyperbaric oxygen became hypothermic under anaesthesia. Hyperbaric oxygen enhanced the radiation response of the tumour in terms of an increase in regrowth delay by a factor of 1.7 when the mice had been anaesthetized, whether or not they became hypothermic. A lower factor of 1.4 was obtained without anaesthesia although induced hypothermia increased the response to a small extent. The authors conclude that anaesthesia and hypothermia affect oxygen metabolism in tumours by different mechanisms. (author)

  16. Periodic Forcing of Inhibition-Stabilized Networks: Nonlinear Resonances and Phase-Amplitude Coupling

    Science.gov (United States)

    Veltz, Romain; Sejnowski, Terrence J.

    2016-01-01

    Inhibition-stabilized networks (ISNs) are neural architectures with strong positive feedback among pyramidal neurons balanced by strong negative feedback from inhibitory interneurons, a circuit element found in the hippocampus and the primary visual cortex. In their working regime, ISNs produce damped oscillations in the γ-range in response to inputs to the inhibitory population. In order to understand the properties of interconnected ISNs, we investigated periodic forcing of ISNs. We show that ISNs can be excited over a range of frequencies and derive properties of the resonance peaks. In particular, we studied the phase-locked solutions, the torus solutions, and the resonance peaks. Periodically forced ISNs respond with (possibly multistable) phase-locked activity, whereas networks with sustained intrinsic oscillations respond more dynamically to periodic inputs with tori. Hence, the dynamics are surprisingly rich, and phase effects alone do not adequately describe the network response. This strengthens the importance of phaseamplitude coupling as opposed to phase-phase coupling in providing multiple frequencies for multiplexing and routing information. PMID:26496044

  17. Targeted radiosensitization of cells expressing truncated DNA polymerase {beta}.

    NARCIS (Netherlands)

    Neijenhuis, S.; Verwijs-Janssen, M.; Broek, Bart van den; Begg, A.C.; Vens, C.

    2010-01-01

    Ionizing radiation (IR) is an effective anticancer treatment, although failures still occur. To improve radiotherapy, tumor-targeted strategies are needed to increase radiosensitivity of tumor cells, without influencing normal tissue radiosensitivity. Base excision repair (BER) and single-strand

  18. Hyperthermic radiosensitization : mode of action and clinical relevance

    NARCIS (Netherlands)

    Kampinga, HH; Dikomey, E

    Purpose: To provide an update on the recent knowledge about the molecular mechanisms of thermal radiosensitization and its possible relevance to thermoradiotherapy. Summary: Hyperthermia is probably the most potent cellular radiosensitizer known to date. Heat interacts with radiation and potentiates

  19. Hippocampal Ripple Oscillations and Inhibition-First Network Models: Frequency Dynamics and Response to GABA Modulators.

    Science.gov (United States)

    Donoso, José R; Schmitz, Dietmar; Maier, Nikolaus; Kempter, Richard

    2018-03-21

    Hippocampal ripples are involved in memory consolidation, but the mechanisms underlying their generation remain unclear. Models relying on interneuron networks in the CA1 region disagree on the predominant source of excitation to interneurons: either "direct," via the Schaffer collaterals that provide feedforward input from CA3 to CA1, or "indirect," via the local pyramidal cells in CA1, which are embedded in a recurrent excitatory-inhibitory network. Here, we used physiologically constrained computational models of basket-cell networks to investigate how they respond to different conditions of transient, noisy excitation. We found that direct excitation of interneurons could evoke ripples (140-220 Hz) that exhibited intraripple frequency accommodation and were frequency-insensitive to GABA modulators, as previously shown in in vitro experiments. In addition, the indirect excitation of the basket-cell network enabled the expression of intraripple frequency accommodation in the fast-gamma range (90-140 Hz), as in vivo In our model, intraripple frequency accommodation results from a hysteresis phenomenon in which the frequency responds differentially to the rising and descending phases of the transient excitation. Such a phenomenon predicts a maximum oscillation frequency occurring several milliseconds before the peak of excitation. We confirmed this prediction for ripples in brain slices from male mice. These results suggest that ripple and fast-gamma episodes are produced by the same interneuron network that is recruited via different excitatory input pathways, which could be supported by the previously reported intralaminar connectivity bias between basket cells and functionally distinct subpopulations of pyramidal cells in CA1. Together, our findings unify competing inhibition-first models of rhythm generation in the hippocampus. SIGNIFICANCE STATEMENT The hippocampus is a part of the brain of humans and other mammals that is critical for the acquisition and

  20. Impact of homologous recombination on individual cellular radiosensitivity

    International Nuclear Information System (INIS)

    Koch, Kerstin; Wrona, Agnieszka; Dikomey, Ekkehard; Borgmann, Kerstin

    2009-01-01

    Purpose: Individual radiosensitivity as measured with in vitro irradiated lymphocytes using metaphase analysis can predict the risk of normal tissue effects after radiotherapy. This parameter is considered to be primarily determined by the cellular repair capacity of DNA double-strand breaks (DSBs). It is now tested to which extent this capacity also depends on homologous recombination (HR), which is a pathway available when cells are in S/G2 phase. Methods: Experiments were performed with CHO K1 cells, in which HR was suppressed via knock-down of RAD51 using RNA interference (RNAi). RAD51 was measured via western and foci formation, cell survival by colony forming, DSBs by γH2AX foci formation, and chromosomal damage using PCC, G0 or G2 assay. Results: In quiescent G1 cells DSB repair is completed 6 h after irradiation. But there is still a substantial fraction of non-repaired DSBs. Most of these DSBs are repaired when G1 cells are stimulated into cell cycle. Suppression of HR by down-regulation of RAD51 did not affect this repair. In contrast, repair was inhibited when cells were irradiated in late S/G2. In line with these data down-regulation of HR did affect survival of cells irradiated in late S/G2, but not in G1. Conclusions: Individual radiosensitivity as measured for G0/1 cells using metaphase analysis does not depend on homologous recombination

  1. Radiosensitivity of peripheral blood lymphocytes in autoimmune disease

    Energy Technology Data Exchange (ETDEWEB)

    Harris, G [Kennedy Inst. of Rheumatology, London (UK). Div. of Experimental Pathology; Cramp, W A; Edwards, J C; George, A M; Sabovljev, S A; Hart, L; Hughes, G R.V. [Hammersmith Hospital, London (UK); Denman, A M [Northwich Park Hospital, Harrow (UK); Yatvin, M B [Wisconsin Clinical Cancer Center, Madison (USA)

    1985-06-01

    The proliferation of peripheral blood lymphocytes, cultured with Con A, can be inhibited by ionizing radiation. Lymphocytes from patients with conditions associated with autoimmunity, such as rheumatoid arthritis, systemic lupus erythematosus and polymyositis, are more radiosensitive than those from healthy volunteers or patients with conditions not associated with autoimmunity. Nuclear material isolated from the lymphocytes of patients with autoimmune diseases is, on average, lighter in density than the nuclear material from most healthy controls. This difference in density is not related to increased sensitivity to ionizing radiation but the degree of post-irradiation change in density (lightening) is proportional to the initial density, i.e. more dense nuclear material always shows a greater upward shift after radiation. The recovery of pre-irradiation density of nuclear material, 1 h after radiation exposure, taken as an indication of DNA repair, correlates with the radiosensitivity of lymphocyte proliferation (Con A response); failure to return to pre-irradiation density being associated with increased sensitivity of proliferative response. These results require extension but, taken with previously reported studied of the effects of DNA methylating agents, support the idea that DNA damage and its defective repair could be important in the aetio-pathogenesis of autoimmune disease.

  2. Dimethoxycurcumin, a metabolically stable analogue of curcumin enhances the radiosensitivity of cancer cells: Possible involvement of ROS and thioredoxin reductase

    Energy Technology Data Exchange (ETDEWEB)

    Jayakumar, Sundarraj; Patwardhan, R.S.; Pal, Debojyoti [Radiation Biology & Health Sciences Division, Modular Laboratories, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Sharma, Deepak [Radiation Biology & Health Sciences Division, Modular Laboratories, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094 (India); Sandur, Santosh K., E-mail: sskumar@barc.gov.in [Radiation Biology & Health Sciences Division, Modular Laboratories, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094 (India)

    2016-09-09

    Dimethoxycurcumin (DIMC), a structural analogue of curcumin, has been shown to have more stability, bioavailability, and effectiveness than its parent molecule curcumin. In this paper the radiosensitizing effect of DIMC has been investigated in A549 lung cancer cells. As compared to its parent molecule curcumin, DIMC showed a very potent radiosensitizing effect as seen by clonogenic survival assay. DIMC in combination with radiation significantly increased the apoptosis and mitotic death in A549 cells. This combinatorial treatment also lead to effective elimination of cancer stem cells. Further, there was a significant increase in cellular ROS, decrease in GSH to GSSG ratio and also significant slowdown in DNA repair when DIMC was combined with radiation. In silico docking studies and in vitro studies showed inhibition of thioredoxin reductase enzyme by DIMC. Overexpression of thioredoxin lead to the abrogation of radiosensitizing effect of DIMC underscoring the role of thioredoxin reductase in radiosensitization. Our results clearly demonstrate that DIMC can synergistically enhance the cancer cell killing when combined with radiation by targeting thioredoxin system. - Highlights: • DIMC enhances radiosensitivity of cancer cells by inducing cell death. • DIMC with radiation disrupted the cellular redox and targeted cancer stem cells. • DNA repair is hampered when cells are treated with DIMC. • DIMC inhibited thioredoxin reductase in cancer cells.

  3. Dimethoxycurcumin, a metabolically stable analogue of curcumin enhances the radiosensitivity of cancer cells: Possible involvement of ROS and thioredoxin reductase

    International Nuclear Information System (INIS)

    Jayakumar, Sundarraj; Patwardhan, R.S.; Pal, Debojyoti; Sharma, Deepak; Sandur, Santosh K.

    2016-01-01

    Dimethoxycurcumin (DIMC), a structural analogue of curcumin, has been shown to have more stability, bioavailability, and effectiveness than its parent molecule curcumin. In this paper the radiosensitizing effect of DIMC has been investigated in A549 lung cancer cells. As compared to its parent molecule curcumin, DIMC showed a very potent radiosensitizing effect as seen by clonogenic survival assay. DIMC in combination with radiation significantly increased the apoptosis and mitotic death in A549 cells. This combinatorial treatment also lead to effective elimination of cancer stem cells. Further, there was a significant increase in cellular ROS, decrease in GSH to GSSG ratio and also significant slowdown in DNA repair when DIMC was combined with radiation. In silico docking studies and in vitro studies showed inhibition of thioredoxin reductase enzyme by DIMC. Overexpression of thioredoxin lead to the abrogation of radiosensitizing effect of DIMC underscoring the role of thioredoxin reductase in radiosensitization. Our results clearly demonstrate that DIMC can synergistically enhance the cancer cell killing when combined with radiation by targeting thioredoxin system. - Highlights: • DIMC enhances radiosensitivity of cancer cells by inducing cell death. • DIMC with radiation disrupted the cellular redox and targeted cancer stem cells. • DNA repair is hampered when cells are treated with DIMC. • DIMC inhibited thioredoxin reductase in cancer cells.

  4. Application of bio-marker to study on tumor radiosensitivity

    International Nuclear Information System (INIS)

    Guo Wanfeng; Ding Guirong; Han Liangfu

    2001-01-01

    To definite tumor radiosensitivity is important for applying the schedules of individualization of patient radiotherapy. Many laboratories were carrying on the research which predict the tumor radiosensitivity with one bio-marker or/and multi-bio-marker in various levels. At present has not witnessed the specific bio-marker, but it provides an excellent model for predicting tumor radiosensitivity

  5. Autophagy involved in resveratrol increased radiosensitivity in glioma stem cells

    International Nuclear Information System (INIS)

    Long Linmei; Zhang Qingqing; Yang Neng; Ji Wenjun; Song Yunzhen; Zhao Jianghu; Liang Zhongqin

    2012-01-01

    Objective: To investigate the effect of Resveratrol combined with X-ray on radiosensitivity in glioma stem cells. Methods: The proliferation inhibition of glioma stem cells induced by X-rays and Resveratrol was assessed with MTT assay. The activation of proapoptotic effect was characterized by Hoechst 33258 stain. MDC stain and Western blot analysis were used to analyze the autophagy mechanism in X-rays-induced death of glioma stem cells. Results: MTT assay indicated that X-rays and Resveratrol decreased the viability of glioma stem cells (P<0.05); we found the proliferative inhibition of glioma stem cells was declined when we used 3-MA to inhibit autophagy(P<0.05). When the cells were treated by the Resveratrol and x-rays, their spherical shape were changed. Apoptosis was induced in glioma stem cells by combined X-rays and Resveratrol as detected by Hoechst 33258 staining. In addition, autophagy was induced in glioma stem cells in the combined treatment group as detected by MDC staining. Western blotting showed that Bcl-2 expression was decreased. in the combined treatment group (P<0.01), and the LC3-Ⅱ expression was increased in the combined treatment group (P<0.01). Conclusion: Resveratrol can increased the radiation sensitivity of glioma stem cells, the apoptosis and autophagy was induced in the glioma stem cells in the combined treatment X-rays and Resveratrol. Our results suggest that autophagy plays an essential role in the regulation of radiosensitization of glioma stem cells. (authors)

  6. Age-dependent radiosensitivity of mouse oocytes

    International Nuclear Information System (INIS)

    Koehler, C.

    1976-01-01

    It has been shown that there are three distinct phases of radiosensitivity in oocytes of prepubertal mice: a period of rapidly increasing sensitivity between 0 and 4 days of age; a period of consistent, high sensitivity between 5 and 18 days of age; and a period of decreasing sensitivity from 19 to at least 21 days of age. Two distinct phases have been demonstrated for the rate of population decline of the oocytes of primary follicles: an initial period of rapid loss from 0 to 4 days of age; and a period of much slower loss from 5 through 23 days of age. Correlations have been drawn between the first two phases of radiosensitivity and morphological changes in the oocyte, and between the third phase of radiosensitivity and endocrinological changes in the maturing animal. The reaction of oocytes to radiation has been separated into two categories: immediate death (within 24 hours); and delayed death (over the entire lifespan of the animal)

  7. Radiosensitizers in cervical cancer. Cisplatin and beyond

    International Nuclear Information System (INIS)

    Candelaria, Myrna; Garcia-Arias, Alicia; Cetina, Lucely; Dueñas-Gonzalez, Alfonso

    2006-01-01

    Cervical cancer continues to be a significant health burden worldwide. Globally, the majority of cancers are locally advanced at diagnosis; hence, radiation remains the most frequently used therapeutical modality. Currently, the value of adding cisplatin or cisplatin-based chemotherapy to radiation for treatment of locally advanced cervical cancer is strongly supported by randomized studies and meta-analyses. Nevertheless, despite these significant achievements, therapeutic results are far from optimal; thus, novel therapies need to be assayed. A strategy currently being investigated is the use of newer radiosensitizers alone or in combination with platinum compounds. In the present work, we present preclinical information on known and newer cytotoxic agents as radiosensitizers on cervical cancer models, as well as the clinical information emanating from early phase trials that incorporate them to the cervical cancer management. In addition, we present the perspectives on the combined approach of radiation therapy and molecular target-based drugs with proven radiosensitizing capacity

  8. Prostate-Specific Natural Health Products (Dietary Supplements) Radiosensitize Normal Prostate Cells

    International Nuclear Information System (INIS)

    Hasan, Yasmin; Schoenherr, Diane; Martinez, Alvaro A.; Wilson, George D.; Marples, Brian

    2010-01-01

    Purpose: Prostate-specific health products (dietary supplements) are taken by cancer patients to alleviate the symptoms linked with poor prostate health. However, the effect of these agents on evidence-based radiotherapy practice is poorly understood. The present study aimed to determine whether dietary supplements radiosensitized normal prostate or prostate cancer cell lines. Methods and Materials: Three well-known prostate-specific dietary supplements were purchased from commercial sources available to patients (Trinovin, Provelex, and Prostate Rx). The cells used in the study included normal prostate lines (RWPE-1 and PWR-1E), prostate tumor lines (PC3, DU145, and LNCaP), and a normal nonprostate line (HaCaT). Supplement toxicity was assessed using cell proliferation assays [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] and cellular radiosensitivity using conventional clonogenic assays (0.5-4Gy). Cell cycle kinetics were assessed using the bromodeoxyuridine/propidium iodide pulse-labeling technique, apoptosis by scoring caspase-3 activation, and DNA repair by assessing γH2AX. Results: The cell growth and radiosensitivity of the malignant PC3, DU145, and LNcaP cells were not affected by any of the dietary prostate supplements (Provelex [2μg/mL], Trinovin [10μg/mL], and Prostate Rx [50 μg/mL]). However, both Trinovin (10μg/mL) and Prostate Rx (6μg/mL) inhibited the growth rate of the normal prostate cell lines. Prostate Rx increased cellular radiosensitivity of RWPE-1 cells through the inhibition of DNA repair. Conclusion: The use of prostate-specific dietary supplements should be discouraged during radiotherapy owing to the preferential radiosensitization of normal prostate cells.

  9. DNA-Dependent Protein Kinase As Molecular Target for Radiosensitization of Neuroblastoma Cells.

    Directory of Open Access Journals (Sweden)

    M Emmy M Dolman

    Full Text Available Tumor cells might resist therapy with ionizing radiation (IR by non-homologous end-joining (NHEJ of IR-induced double-strand breaks. One of the key players in NHEJ is DNA-dependent protein kinase (DNA-PK. The catalytic subunit of DNA-PK, i.e. DNA-PKcs, can be inhibited with the small-molecule inhibitor NU7026. In the current study, the in vitro potential of NU7026 to radiosensitize neuroblastoma cells was investigated. DNA-PKcs is encoded by the PRKDC (protein kinase, DNA-activated, catalytic polypeptide gene. We showed that PRKDC levels were enhanced in neuroblastoma patients and correlated with a more advanced tumor stage and poor prognosis, making DNA-PKcs an interesting target for radiosensitization of neuroblastoma tumors. Optimal dose finding for combination treatment with NU7026 and IR was performed using NGP cells. One hour pre-treatment with 10 μM NU7026 synergistically sensitized NGP cells to 0.63 Gy IR. Radiosensitizing effects of NU7026 increased in time, with maximum effects observed from 96 h after IR-exposure on. Combined treatment of NGP cells with 10 μM NU7026 and 0.63 Gy IR resulted in apoptosis, while no apoptotic response was observed for either of the therapies alone. Inhibition of IR-induced DNA-PK activation by NU7026 confirmed the capability of NGP cells to, at least partially, resist IR by NHEJ. NU7026 also synergistically radiosensitized other neuroblastoma cell lines, while no synergistic effect was observed for low DNA-PKcs-expressing non-cancerous fibroblasts. Results obtained for NU7026 were confirmed by PRKDC knockdown in NGP cells. Taken together, the current study shows that DNA-PKcs is a promising target for neuroblastoma radiosensitization.

  10. DNA-Dependent Protein Kinase As Molecular Target for Radiosensitization of Neuroblastoma Cells.

    Science.gov (United States)

    Dolman, M Emmy M; van der Ploeg, Ida; Koster, Jan; Bate-Eya, Laurel Tabe; Versteeg, Rogier; Caron, Huib N; Molenaar, Jan J

    2015-01-01

    Tumor cells might resist therapy with ionizing radiation (IR) by non-homologous end-joining (NHEJ) of IR-induced double-strand breaks. One of the key players in NHEJ is DNA-dependent protein kinase (DNA-PK). The catalytic subunit of DNA-PK, i.e. DNA-PKcs, can be inhibited with the small-molecule inhibitor NU7026. In the current study, the in vitro potential of NU7026 to radiosensitize neuroblastoma cells was investigated. DNA-PKcs is encoded by the PRKDC (protein kinase, DNA-activated, catalytic polypeptide) gene. We showed that PRKDC levels were enhanced in neuroblastoma patients and correlated with a more advanced tumor stage and poor prognosis, making DNA-PKcs an interesting target for radiosensitization of neuroblastoma tumors. Optimal dose finding for combination treatment with NU7026 and IR was performed using NGP cells. One hour pre-treatment with 10 μM NU7026 synergistically sensitized NGP cells to 0.63 Gy IR. Radiosensitizing effects of NU7026 increased in time, with maximum effects observed from 96 h after IR-exposure on. Combined treatment of NGP cells with 10 μM NU7026 and 0.63 Gy IR resulted in apoptosis, while no apoptotic response was observed for either of the therapies alone. Inhibition of IR-induced DNA-PK activation by NU7026 confirmed the capability of NGP cells to, at least partially, resist IR by NHEJ. NU7026 also synergistically radiosensitized other neuroblastoma cell lines, while no synergistic effect was observed for low DNA-PKcs-expressing non-cancerous fibroblasts. Results obtained for NU7026 were confirmed by PRKDC knockdown in NGP cells. Taken together, the current study shows that DNA-PKcs is a promising target for neuroblastoma radiosensitization.

  11. Radiosensitivity of carcinoma of esophagus

    International Nuclear Information System (INIS)

    Furusawa, Hidenori

    1986-01-01

    With a detailed graphic reconstruction of radiation effects shown in 11 operation materials of carcinoma of esophagus with preoperative irradiation, histologic analysis of the radiosensitivity was made. Residual cancer lesions in 11 operation specimens contained adenocarcinoma elements. Carcinoma of esophagus belonged to mixed carcinoma (syn. metaplastic cancer). Radioresistant nature resulted from the remnant adenocarcinoma elements. Protruded type (3 cases) showed about 60 % of residual cancer after preoperative irradiation of 40 Gy (Lineac or 60 Co.). The residual cancer nests histologically revealed well-differentiated squamous cell carcinoma with a few signet-ring cells, compatible with mucoepidermoid carcinoma. In protruded type, the mixed carcinoma was composed of segmental, disproportioned zonal squamous metaplasia. As its histogenetic origin, a main duct of esophageal gland was suggested. In 9 autopsy cases of esophageal cancer, recurrent lesion within the field of irradiation failed to respond to radiotherapy. In recurrent residual lesions, a higher proportion of adenocarcinoma elements was noticed. Therefore, the cancer part formed by a high rate of metaplasia was markedly responsive to irradiation, whereas increased residue of adenocarcinoma elements was enhanced the radioresistant property. In a middle thoracic esophagus (Im) corresponding to the commonest site of esophageal cancer, the distribution of esohageal glands was in a high density with a constant ratio of density in each age group particularly in male. In age groups with higher incidence of carcinoma of esophagus, esophageal glands markedly increased especially in male, in contrast with the indefinite number and density ratio in female cases. A high density of esophageal glands was noticed in the upper (Iu) and lower (Im) parts of the 2nd physiologic constriction, in proportion to the commonest site of carcinoma of esophagus. (J.P.N.)

  12. Network state-dependent inhibition of identified hippocampal CA3 axo-axonic cells in vivo

    Science.gov (United States)

    Tukker, John J; Klausberger, Thomas; Somogyi, Peter

    2015-01-01

    Hippocampal sharp waves are population discharges initiated by an unknown mechanism in pyramidal cell networks of CA3. Axo-axonic cells (AACs) regulate action potential generation through GABAergic synapses on the axon initial segment. We found that CA3 AACs in anesthetized rats and AACs in freely moving rats stopped firing during sharp waves, when pyramidal cells fire most. AACs fired strongly and rhythmically around the peak of theta oscillations, when pyramidal cells fire at low probability. Distinguishing AACs from other parvalbumin-expressing interneurons by their lack of detectable SATB1 transcription factor immunoreactivity, we discovered a somatic GABAergic input originating from the medial septum that preferentially targets AACs. We recorded septo-hippocampal GABAergic cells that were activated during hippocampal sharp waves and projected to CA3. We hypothesize that inhibition of AACs, and the resulting subcellular redistribution of inhibition from the axon initial segment to other pyramidal cell domains, is a necessary condition for the emergence of sharp waves promoting memory consolidation. PMID:24141313

  13. Monetary Reward and Punishment to Response Inhibition Modulate Activation and Synchronization Within the Inhibitory Brain Network

    Directory of Open Access Journals (Sweden)

    Rupesh K. Chikara

    2018-03-01

    Full Text Available A reward or punishment can modulate motivation and emotions, which in turn affect cognitive processing. The present simultaneous functional magnetic resonance imaging-electroencephalography study examines neural mechanisms of response inhibition under the influence of a monetary reward or punishment by implementing a modified stop-signal task in a virtual battlefield scenario. The participants were instructed to play as snipers who open fire at a terrorist target but withhold shooting in the presence of a hostage. The participants performed the task under three different feedback conditions in counterbalanced order: a reward condition where each successfully withheld response added a bonus (i.e., positive feedback to the startup credit, a punishment condition where each failure in stopping deduced a penalty (i.e., negative feedback, and a no-feedback condition where response outcome had no consequences and served as a control setting. Behaviorally both reward and punishment conditions led to significantly down-regulated inhibitory function in terms of the critical stop-signal delay. As for the neuroimaging results, increased activities were found for the no-feedback condition in regions previously reported to be associated with response inhibition, including the right inferior frontal gyrus and the pre-supplementary motor area. Moreover, higher activation of the lingual gyrus, posterior cingulate gyrus (PCG and inferior parietal lobule were found in the reward condition, while stronger activation of the precuneus gyrus was found in the punishment condition. The positive feedback was also associated with stronger changes of delta, theta, and alpha synchronization in the PCG than were the negative or no-feedback conditions. These findings depicted the intertwining relationship between response inhibition and motivation networks.

  14. On the Path to Seeking Novel Radiosensitizers

    International Nuclear Information System (INIS)

    Katz, David; Ito, Emma; Liu Feifei

    2009-01-01

    Radiation therapy is a highly effective cancer treatment modality, and extensive investigations have been undertaken over the years to augment its efficacy in the clinic. This review summarizes the current understanding of the biologic bases underpinning many of the clinically used radiosensitizers. In addition, this review illustrates how the advent of innovative, high-throughput technologies with integration of different disciplines could be harnessed for an expeditious discovery process for novel radiosensitizers, providing an exciting future for such pursuits in radiation biology and oncology

  15. Induction of thermal shock proteins and changes in radiosensitivity after heat treatment of Bombyx mori L. embryos

    International Nuclear Information System (INIS)

    Agaev, F.A.

    1993-01-01

    The method of gel-electrophoresis was used to study thermal shock protein synthesis in Bombyx mori embryos exposed to a mixture of heat and gamma-radiation. Induction of thermal shock protein synthesis was not inhibited by gamma-radiation. It is suggested that thermal shock proteins are involved embryo radiosensitivity modification

  16. Silencing the Girdin gene enhances radio-sensitivity of hepatocellular carcinoma via suppression of glycolytic metabolism.

    Science.gov (United States)

    Yu, Li; Sun, Yifan; Li, Jingjing; Wang, Yan; Zhu, Yuxing; Shi, Yong; Fan, Xiaojun; Zhou, Jianda; Bao, Ying; Xiao, Jie; Cao, Ke; Cao, Peiguo

    2017-08-15

    Radiotherapy has been used increasingly to treat primary hepatocellular carcinoma. Clinically, the main cause of radiotherapy failure is cellular radioresistance, conferred via glycolytic metabolism. Our previous study demonstrated that Girdin is upregulated in primary hepatocellular carcinoma and promotes the invasion and metastasis of tumor cells. However, whether Girdin underlies the radio-sensitivity of hepatocellular carcinoma remains unclear. A short hairpin RNA (shRNA) was used to silence CCDC88A (encoding Girdin), and real-time PCR was performed to determine CCDC88A mRNA expression. Then, cell proliferation, colony formation, flow cytometric, scratch, and transwell assays were to examine the influence of Girdin silencing on cellular radiosensitivity. Glycolysis assays were conducted to exam cell glycolysis process. Western blotting was performed to explore the signaling pathway downstream of Girdin. Finally, animal experiments were performed to demonstrate the effect of CCDC88A silencing on the radiosensitivity of hepatoma in vivo. shRNA-induced Girdin silencing suppressed glycolysis and enhanced the radio-sensitivity of hepatic cell lines, HepG2 and Huh-7. Furthermore, silencing of Girdin inhibited the PI3K/AKT/HIF-1α signaling pathway, which is a central regulator of glycolysis. Girdin can regulate glycolysis in hepatocellular carcinoma cells through the PI3K/AKT/HIF-1α signaling pathway, which decreases the sensitivity of tumor cells to radiotherapy.

  17. Modification of the radiosensitizing effect of metronidazole by 5-fluorouracil and caffeine

    International Nuclear Information System (INIS)

    Esel'baeva, G.O.; Ermekova, S.A.

    1986-01-01

    A study was made of the combined effect of 5-fluorouracil, metronidazole, caffeine and radiation on radiosensitivity of Pliss lymphosarcoma and protein synthesis rate during the first few hours following irradiation. A complete regression of the tumor was noted in 100% of animals after a 3-fold exposure. Effective postirradiation inhibition of protein synthesis was achieved by injection of metronidazole and caffeine together with 5-fluorouracil

  18. Release from the Crabtree effect by hypoxic cell radiosensitizers

    International Nuclear Information System (INIS)

    Mustea, I.; Bara, A.

    1979-01-01

    The Crabtree effect can be observed when the 0 2 consumption of tumour cells or of mammalian cells grown in culture is measured in physiological medium containing glucose. The effect of 2 hypoxic cell radiosensitizers, misonidazole and NDPP, on the 0 2 consumption of Ehrlich ascites tumour cells was compared in media with and without glucose. A stimulatory effect on 0 2 consumption was found for 5-20 mM misonidazole as well as for 0.5mM NDPP, both in media containing 10 -2 M glucose. Thus glucose induced a Crabtree effect in Ehrlich tumour cells, expressed as 38-45% inhibition of 0 2 consumption relative to that in the same medium without glucose. The stimulatory effect of misonidazole and NDPP on 0 2 utilization in medium with glucose undoubtedly appeared as a release from the Crabtree effect. (author)

  19. Radiosensitivity in seeds of Coix lachryma-jobi TOURN

    Energy Technology Data Exchange (ETDEWEB)

    Gabrielli, A C [Universidade Estadual de Campinas (Brazil). Inst. de Biologia; Medina Filho, H P [Instituto Agronomico de Campinas (Brazil)

    1979-04-01

    Radiosensitivity in seeds of Coix lachryma-jobi Tourn. Seeds of Coix lachryma-jobi Tourn., containing 9% humidity were irradiated with 0 to 70 Krad doses of gama-radiation from a /sup 60/Co source. The zero-time was set to be the time of sowing. At high doses of radiation, germination after 15 days was little affected, but after 21 days survival rate decreased. Our results show that the LD/sub 50/ is about 60 Krad and the GR/sub 50/ is approximately 30 Krad. The morphological alterations which were observed in some plants, as well as the effects of gama-radiation on growth inhibition and survival rate of the seedlings, suggest that doses between 30 and 50 Krad could be useful to obtain genetic variability in adapted cultivars of this species.

  20. Radiosensitivity of quince seeds (Cydonia oblonga Mill.)

    International Nuclear Information System (INIS)

    Dall'Orto, F.A.C.; Ojima, M.; Hiroce, R.; Igue, T.; Ferraz, E.S.B.; Nascimento Filho, V.F. do; Menten, J.O.M.; Tulmann Neto, A.; Ando, A.

    1984-01-01

    The investigation with quince seeds (Cydonia oblonga Mill.) radiosensitivity and the mineral composition of the plants obtained for mutation breeding are related. The concentration of some macro and micronutrients in quince seedlings obtained from irradiated seeds are studied. (M.A.C.) [pt

  1. Radiosensitivity of human lymphocytes and thymocytes

    International Nuclear Information System (INIS)

    Kwan, D.K.; Norman, A.

    1977-01-01

    The in vitro survival of human peripheral blood lymphocytes and thymocytes was measured 4 days following graded doses of γ radiation. Results indicate considerable heterogeneity among lymphocyte subpopulations with respect to radiosensitivity. Total T lymphocytes were characterized by rosette formation with neuraminidase-treated sheep red blood cells (nSRBC); early T (T/sub E/) cells, by early rosettes; and B cells, by their inability to form nSRBC rosettes. Late T (T/sub L/) cells were defined as T -- T/sub E/. Survival curves of T, T/sub E/, and B cells are biphasic. The radiosensitive and radioresistant components of T, T/sub E/, and B cells all have a D 0 of about 50 and 550 rad, respectively. B cells appeared to be slightly more radiosensitive than T cells. T/sub L/ cells and thymocytes, however, appeared to be homogeneous with respect to radiosensitivity, both having D 0 values of about 135 rad. The survival of T cells in mixed T and B cell cultures resembled that of separated T cells, suggesting that ionizing radiation has no significant effect on rosette formation. It also indicates that interactions of T and B cells do not significantly affect their radiation responses

  2. Osmotic homeostasis and NKLy lymphoma cells radiosensitivity

    International Nuclear Information System (INIS)

    Tishchenko, V.V.; Magda, I.N.

    1992-01-01

    In experiments with cells of ascites NKLy lymphoma differing in ploidy and position in the cell cycle, a study was made of the radiosensitivity, osmotic homeostasis peculiarities and thermoradiation changes in potassium content. It was shown that the resistance of osmotic homeostasis of NKLy cells to thermoradiation correlated with their radioresistance

  3. Photosensitizers and radiosensitizers in dermatology and oncology

    International Nuclear Information System (INIS)

    Bruckner, V.

    1979-01-01

    Two therapeutic modalities are currently of great interest, namely photo- and radiosensitization. Whereas photosensitizers only function in combination with ultraviolet (UV) light, radiosensitizers act only in combination with ionizing radiation. Because of the small UV penetration, up to a maximum of 0,5 mm, photosensitization can take place only at the surface of the body, i.e. the skin. Photosensitizers are applied in dermatology in order to optimize and improve the UV therapy of certain diseases (mainly psoriasis, mycosis fungoides and vitiligo). Radiosensitizers lead to an increase in sensitivity of the hypoxic and therefore radioresistant parts of tumours against X- and gamma-radiation. With sufficient concentration within the tumour, they can act where the radiation can reach, even in the deeper parts of the body. They represent a modern and useful aid to radiation oncology. Because of neurotoxic effects, however, their practical use is limited. A short review of the history, mechanisms of action, application and side-effects of these photo- and radiosensitizers is presented

  4. Photosensitizers and radiosensitizers in dermatology and oncology

    Energy Technology Data Exchange (ETDEWEB)

    Bruckner, V [Stellenbosch University, Parowvallei (South Africa). Departments of Medical Physics and Radiology

    1979-09-22

    Two therapeutic modalities are currently of great interest, namely photo- and radiosensitization. Whereas photosensitizers only function in combination with ultraviolet (UV) light, radiosensitizers act only in combination with ionizing radiation. Because of the small UV penetration, up to a maximum of 0,5 mm, photosensitization can take place only at the surface of the body, i.e. the skin. Photosensitizers are applied in dermatology in order to optimize and improve the UV therapy of certain diseases (mainly psoriasis, mycosis fungoides and vitiligo). Radiosensitizers lead to an increase in sensitivity of the hypoxic and therefore radioresistant parts of tumours against X- and gamma-radiation. With sufficient concentration within the tumour, they can act where the radiation can reach, even in the deeper parts of the body. They represent a modern and useful aid to radiation oncology. Because of neurotoxic effects, however, their practical use is limited. A short review of the history, mechanisms of action, application and side-effects of these photo- and radiosensitizers is presented.

  5. Expression of hPNAS-4 Radiosensitizes Lewis Lung Cancer

    International Nuclear Information System (INIS)

    Zeng Hui; Yuan Zhu; Zhu Hong; Li Lei; Shi Huashan; Wang Zi; Fan Yu; Deng Qian; Zeng Jianshuang; He Yinbo; Xiao Jianghong; Li Zhiping

    2012-01-01

    Purpose: This study aimed to transfer the hPNAS-4 gene, a novel apoptosis-related human gene, into Lewis lung cancer (LL2) and observe its radiosensitive effect on radiation therapy in vitro and in vivo. Methods and Materials: The hPNAS-4 gene was transfected into LL2 cells, and its expression was detected via western blot. Colony formation assay and flow cytometry were used to detect the growth and apoptosis of cells treated with irradiation/PNAS-4 in vitro. The hPNAS-4 gene was transferred into LL2-bearing mice through tail vein injection of the liposome/gene complex. The tumor volumes were recorded after radiation therapy. Proliferating cell nuclear antigen (PCNA) immunohistochemistry staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay were performed to detect the tumor cell growth and apoptosis in vivo. Results: The hPNAS-4 gene was successfully transferred into LL2 cells and tumor tissue, and its overexpressions were confirmed via western blot analysis. Compared with the control, empty plasmid, hPNAS-4, radiation, and empty plasmid plus radiation groups, the hPNAS-4 plus radiation group more significantly inhibited growth and enhanced apoptosis of LL2 cells in vitro and in vivo (P<.05). Conclusions: The hPNAS-4 gene was successfully transferred into LL2 cells and tumor tissue and was expressed in both LL2 cell and tumor tissue. The hPNAS-4 gene therapy significantly enhanced growth inhibition and apoptosis of LL2 tumor cells by radiation therapy in vitro and in vivo. Therefore, it may be a potential radiosensitive treatment of radiation therapy for lung cancer.

  6. Synaptic excitation in spinal motoneurons alternates with synaptic inhibition and is balanced by outward rectification during rhythmic motor network activity

    DEFF Research Database (Denmark)

    Guzulaitis, Robertas; Hounsgaard, Jorn

    2017-01-01

    channels. Intrinsic outward rectification facilitates spiking by focusing synaptic depolarization near threshold for action potentials. By direct recording of synaptic currents, we also show that motoneurons are activated by out-of-phase peaks in excitation and inhibition during network activity, whereas......Regular firing in spinal motoneurons of red-eared turtles (Trachemys scripta elegans, either sex) evoked by steady depolarization at rest is replaced by irregular firing during functional network activity. The transition caused by increased input conductance and synaptic fluctuations in membrane...... potential was suggested to originate from intense concurrent inhibition and excitation. We show that the conductance increase in motoneurons during functional network activity is mainly caused by intrinsic outward rectification near threshold for action potentials by activation of voltage and Ca2+ gated K...

  7. Prenyltransferase inhibitor radiosensitization of pancreatic ductal carcinoma (PaCa) cells

    International Nuclear Information System (INIS)

    Brunner, T.B.; Hahn, S.M.; Rustgi, A.K.

    2003-01-01

    Farnesyltransferase inhibitors (FTIs) radiosensitize tumor cell lines expressing activated H-Ras. K-Ras however remains active after FTI treatment due to prenylation by geranylgeranyltransferase. Up to 90% of pancreatic carcinomas (PaCa) are mutant in K-ras. We hypothesized that combined FTI and geranylgeranyltransferase inhibitor (GGTI) treatment could radiosensitize PaCa cells. Nine human PaCa lines (7 K-ras-mutant, 2 ras-wt) and transgenic mouse pancreatic ductal cells (PDC) expressing wt-ras or mutant K-ras were tested in clonogenic assays with combined FTI-A +/- GGTI-B (Merck and Co Inc.). Inhibition of PI3- kinase (with LY294002) or inhibition of MEK1/2 (with U0126) served to assess the significance of the PI3-kinase and MAPK to radiation survival in these cells. H- and K-Ras prenylation status and changes in phosphorylation of AKT and MAPK were monitored as were changes in cell cycle distribution. FTI+GGTI treatment achieved inhibition of K-Ras prenylation in all PaCa cell lines. This treatment radiosensitized the K-ras mutant cell lines AsPC-1, Capan-2, MiaPaCa-2 and PSN-1, PancM, but not Capan-1 or the ras-wt cell lines (BxPC-3, HS766T, PDC-wt). L-778,123, a dual action inhibitor, sensitized all K-ras mutant cells. Surprisingly, PancM, Panc-1, MiaPaCa-2 and PDC K-Ras cells were radiosensitized by FTI treatment alone. R11577, another FTI without GGTI activity, also sensitized Panc-1 and MiaPaCa-2 and additionally AsPC-1 cells. Radiosensitization was also achieved after treatment with LY294002 in all PaCa lines expressing mutant-K-ras and the ras-wt line BxPC-3 overexpressing Akt2. However these lines were not sensitized by U0126. FTI+GGTI sensitize K-ras mt PaCa cell lines to radiation. PI3-kinase signaling but not MAPK signaling appears to contribute to radiation survival in PaCa cells. Radiosensitization of certain PaCa cells by FTI alone indicates that alternate pathways or farnesylated targets other than K-Ras may also be involved in radiation survival

  8. Amplification of asynchronous inhibition-mediated synchronization by feedback in recurrent networks.

    Directory of Open Access Journals (Sweden)

    Sashi Marella

    2010-02-01

    Full Text Available Synchronization of 30-80 Hz oscillatory activity of the principle neurons in the olfactory bulb (mitral cells is believed to be important for odor discrimination. Previous theoretical studies of these fast rhythms in other brain areas have proposed that principle neuron synchrony can be mediated by short-latency, rapidly decaying inhibition. This phasic inhibition provides a narrow time window for the principle neurons to fire, thus promoting synchrony. However, in the olfactory bulb, the inhibitory granule cells produce long lasting, small amplitude, asynchronous and aperiodic inhibitory input and thus the narrow time window that is required to synchronize spiking does not exist. Instead, it has been suggested that correlated output of the granule cells could serve to synchronize uncoupled mitral cells through a mechanism called "stochastic synchronization", wherein the synchronization arises through correlation of inputs to two neural oscillators. Almost all work on synchrony due to correlations presumes that the correlation is imposed and fixed. Building on theory and experiments that we and others have developed, we show that increased synchrony in the mitral cells could produce an increase in granule cell activity for those granule cells that share a synchronous group of mitral cells. Common granule cell input increases the input correlation to the mitral cells and hence their synchrony by providing a positive feedback loop in correlation. Thus we demonstrate the emergence and temporal evolution of input correlation in recurrent networks with feedback. We explore several theoretical models of this idea, ranging from spiking models to an analytically tractable model.

  9. Tumour-specific radiosensitizers for radiation therapy

    International Nuclear Information System (INIS)

    Denekamp, J.

    1977-01-01

    Recently Adams and coworkers at the Gray Laboratory have developed a new class of radiosensitizers which act specifically on hypoxic cells by abolishing the protection afforded by low oxygen concentrations. Since most experimental tumours contain a high proportion of oxygen-deprived cells, and most normal tissues are well oxygenated, these drugs are tumour specific radiosensitizers. Based on the hypothesis that sensitization increases with increasing electron affinity, the two nitroimidazoles, metronidazole (Flagyl) and Ro-07/0582 were identified as potent radiosensitizers with low toxicity. These drugs are effective only in the absence of oxygen, and only if the drug is present at the time of irradiation. The degree of sensitization increases with drug concentration rapidly over the range 0.1 to 1.0mg/g body weight for Ro-07-0582, and more gradually for Flagyl. Tumour studies have been performed on at least 12 different experimental tumours, using a variety of end points. Significant sensitization has been observed in every tumour studied, often corresponding to a dose reduction factor of 2.0 for high but non-toxic drug doses. Fractionated studies have also been performed on a few tumour lines. In most cases a useful therapeutic advantage was observed, although the sensitization was smaller. Ro-07-0582 used with X-rays gives a therapeutic gain comparable with that from cyclotron-produced fast neutrons. Neutrons used together with Ro-07-0582 are even more effective. In addition to the radiosensitization there is a specific cytotoxicity to hypoxic cells after prolonged exposure to Ro-07-0582. This cytotoxicity can be greatly enhanced in vitro by moderate hyperthermia. Flagyl and Ro-07-0582 have been used clinically as radiosensitizers, with promising early results. The clinical application is limited to certain dose fractionation patterns because of neurotoxicity. (author)

  10. Chromosomal radiosensitivity of prostate cancer patients

    International Nuclear Information System (INIS)

    McRobbie, M.L.; Riches, A.; Baxby, K.

    2003-01-01

    Full text: Radiosensitivity of peripheral blood lymphocytes from prostate cancer patients is being investigated using the G2 assay and the Cytokinesis Block Micronucleus(CBMN)assay. The G2 assay evaluates chromosomal damage caused by irradiating cells in the G2 phase of the cell cycle. The CBMN assay quantifies the post mitotic micronuclei, which are the expression of damage incurred during G0. An association between hypersensitivity to the chromosome damaging effects of ionising radiation and cancer predispostion has been demonstrated in a number of heritable conditions by using the aforementioned techniques. Recently, increased chromosomal radiosensitivity has been demonstrated in a significant proportion of patients with no obvious family history of malignancy. The aim of this study is to establish whether a group of prostatic carcinoma patients exists and if so whether there are any correlations between their G2 and G0 sensitivities. The study has shown there is no correlation between G2 and G0 sensitivity, confirming the general trend that individuals exhibiting chromosomal radiosensitivity are defective in only one mechanism and G2 and G0 sensitivity are largely independent. Current data indicates that there is an identifiable group of men within the prostate cancer population with increased chromosomal radiosensitivity. Using the G2 assay and the 90th percentile of the controls as a cut off point for sensitivity, no significant difference between the controls and the patient population has been found. However, using the CBMN assay and again the 90th percentile, approximately 11% of the control group are sensitive compared with approximately 40% of the carcinoma cases. The implications of this increased radiosensitivity are as yet unclear, but it is indicative of increased chromosomal fragility and therefore, possibly associated with malignant transformation. Hence, it may prove a useful tool in identifying individuals at increased risk of developing

  11. Triolimus: A Multi-Drug Loaded Polymeric Micelle Containing Paclitaxel, 17-AAG, and Rapamycin as a Novel Radiosensitizer.

    Science.gov (United States)

    Tomoda, Keishiro; Tam, Yu Tong; Cho, Hyunah; Buehler, Darya; Kozak, Kevin R; Kwon, Glen S

    2017-01-01

    Triolimus is a multi-drug loaded polymeric micelle containing paclitaxel (PTX), 17-allylamino-17-demethoxygeldanamycin (17-AAG), and rapamycin (RAP). This study examines the radiosensitizing effect of Triolimus in vitro and in vivo. Radiosensitizing effects of Triolimus on A549 cells are dose dependent and at 2 × 10 -9 m, Triolimus shows significant radiosensitization even at low radiation doses (2 Gy). By sensitivity enhancement ratio, PTX alone, dual drug combinations, and Triolimus treatment at 2 × 10 -9 m have radiosensitizing effects with potency as follows: PTX alone (PTX) > PTX and RAP (P/R) > Triolimus (TRIO) > PTX and 17-AAG (P/17) >17-AAG and RAP (17/R). In vivo, fractionated radiation of 15 Gy preceded by infusion of PTX alone, dual drug combinations, or an intermediate dose of Triolimus (Int. TRIO: PTX/17-AAG/RAP at 15/15/7.5 mg kg -1 ) strongly inhibits A549 tumor growth. Notably, pretreatment with high dose of Triolimus (High TRIO: PTX/17-AAG/RAP at 60/60/30 mg kg -1 ) before the fractionated radiation leads to tumor control for up to 24 weeks. An enhanced radiosensitizing effect is observed without an increase in acute toxicity compared to PTX alone or radiation alone. These results suggest that further investigations of Triolimus in combination with radiation therapy are merited. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Radiosensitization by SAHA in Experimental Colorectal Carcinoma Models-In Vivo Effects and Relevance of Histone Acetylation Status

    International Nuclear Information System (INIS)

    Folkvord, Sigurd; Ree, Anne Hansen; Furre, Torbjorn; Halvorsen, Thomas; Flatmark, Kjersti

    2009-01-01

    Purpose: Histone deacetylase inhibitors are being evaluated as antitumor agents in ongoing clinical trials, and promising preclinical results, combined with favorable toxicity profiles, have rendered the drugs as interesting candidates for combination with other treatment modalities, such as radiotherapy. The aim of the present study was to evaluate the radiosensitizing properties of suberoylanilide hydroxamic acid (SAHA) and the possible requirement of histone hyperacetylation at radiation exposure. Methods and materials: Radiosensitization by SAHA was assessed in a colorectal carcinoma cell line and in two colorectal xenograft models by analysis of clonogenic survival and tumor growth delay, respectively. Histone acetylation status at radiation exposure was evaluated by Western blot. Results: In vitro, radiosensitization was demonstrated when cells were preincubated with SAHA, and, in the xenografts, tumor growth was delayed when the mice were treated with fractionated radiation combined with daily SAHA injections compared with radiation alone. Surprisingly, the SAHA-dependent growth delay was still present when radiation was delivered at restored baseline acetylation levels compared with maximal histone hyperacetylation. Conclusion: SAHA was an effective radiosensitizer in experimental colorectal carcinoma models, suggesting that histone deacetylase inhibition might constitute a valuable supplement to current multimodal treatment strategies in rectal cancer. The presence of histone hyperacetylation at radiation was not required to obtain an increased radiation response, questioning the validity of using histone hyperacetylation as a molecular marker for radiosensitivity.

  13. Experimental studies on the radiosensitizing agents against cultured human glioblastoma and human neurinoma

    International Nuclear Information System (INIS)

    Sawatari, Yutaka

    1976-01-01

    The radiosensitivity increasing effect of bromo-2'-deoxyuridine (BUdR) and 5-fluorouracil (5-FU), alone and in combination, was studied comparatively using tissue culture of brain tumor cells (No. 60 cells originating in human glioblastoma and N cells originating in human neurinoma) with colony formation and growth curve as the quantitative indices and the phase contrast microscope and scanning electron microscope for morphological observation. The inhibitive effect of BUdR on growth of the N cells was above 4μg/ml, while 3000μg/ml was required in the case of the No. 60 cells. This indicates that there is a large difference between the sensitivities of these two cell types against BUdR. Increased sensitivity can be anticipated by pretreatment of the No. 60 cells or the N cells with BUdR with a dose of no growth inhibition effect. N cells have a lower radiosensitivity than No. 60 cells; but when both cells are pretreated with BUdR, N cells have a higher radiosensitivity than No. 60 cells. This increasing radiosensitivity of the N cells, which is clinically benign, suggests the possibility of wider application for radiotherapy in the future. A dose of 2μg/ml of 5-FU alone showed no growth inhibiting effect on either the N cells or the No. 60 cells, but it intensified the effect of BUdR. Using a phase contrast microscope and a scanning electron microscope for morphological observation of the No. 60 cells and the N cells which had been exposed to BUdR+5-FU+X-ray, unique findings were observed on the surface structures of these two kinds of cells. (J.P.N.)

  14. Radiosensitivity and cell kinetics of the human solid cancer transplanted to nude mouse

    International Nuclear Information System (INIS)

    Ikeuchi, Shunji

    1983-01-01

    This study was undertaken to analyse the relationship between radiosensitivity and cell kinetics of human solid cancer in experimental nude mouse system. Four strains of tumors used for the experiment were poorly differentiated squamous cell carcinoma of the lung (Lu-9), oat cell carcinoma of the lung (Lu-24), well differentiated squamous cell carcinoma of the tongue (To-1) and moderately differentiated squamous cell carcinoma of the esophagus (Es-4) which were serially transplantable to BALB/c nude mice. Radiosensitivity was evaluated by tumor growth in terms of inhibition rate, histological change and host reaction after irradiation. Cell kinetics were studied by autoradiography with pulse administration of 3 H-thymidine to mice. Although Lu-24 was most radiosensitive, followed by To-1, Es-4 and Lu-9 in the order of sensitivity, it was suggested that they might be more radioresistant in nude mice without T-cell function than in human. Regarding squamous cell carcinomas, well differentiated type was more radiosensitive than poorly differentiated one. All of these tumors in nude mouse revealed distinct percent labeled mitosis curves with two clear peaks which were quite different from those in human body. Lu-24 showed a characteristic pattern with a long time lag before visible growth, short G 1 , and low growth fraction, compared to other three tumors. Three strains of squamous cell carcinoma demonstrated similar cell kinetic factors which were almost the same as those in human body reported previously. The differences in volume doubling time of tumor, growth fraction and cell loss factor were partially related to those of radiosensitivities among tumors except for Lu-24. The theoretical volume doubling time was proved to be most reliable for estimation of effectiveness of irradiation, but the labeling index was not a valuable indicator for it. (author)

  15. DNMT (DNA methyltransferase) inhibitors radiosensitize human cancer cells by suppressing DNA repair activity

    International Nuclear Information System (INIS)

    Kim, Hak Jae; Kim, Jin Ho; Chie, Eui Kyu; Da Young, Park; Kim, In Ah; Kim, Il Han

    2012-01-01

    Histone modifications and DNA methylation are two major factors in epigenetic phenomenon. Unlike the histone deacetylase inhibitors, which are known to exert radiosensitizing effects, there have only been a few studies thus far concerning the role of DNA methyltransferase (DNMT) inhibitors as radiosensitizers. The principal objective of this study was to evaluate the effects of DNMT inhibitors on the radiosensitivity of human cancer cell lines, and to elucidate the mechanisms relevant to that process. A549 (lung cancer) and U373MG (glioblastoma) cells were exposed to radiation with or without six DNMT inhibitors (5-azacytidine, 5-aza-2'-deoxycytidine, zebularine, hydralazine, epigallocatechin gallate, and psammaplin A) for 18 hours prior to radiation, after which cell survival was evaluated via clonogenic assays. Cell cycle and apoptosis were analyzed via flow cytometry. Expressions of DNMT1, 3A/3B, and cleaved caspase-3 were detected via Western blotting. Expression of γH2AX, a marker of radiation-induced DNA double-strand break, was examined by immunocytochemistry. Pretreatment with psammaplin A, 5-aza-2'-deoxycytidine, and zebularine radiosensitized both A549 and U373MG cells. Pretreatment with psammaplin A increased the sub-G1 fraction of A549 cells, as compared to cells exposed to radiation alone. Prolongation of γH2AX expression was observed in the cells treated with DNMT inhibitors prior to radiation as compared with those treated by radiation alone. Psammaplin A, 5-aza-2'-deoxycytidine, and zebularine induce radiosensitivity in both A549 and U373MG cell lines, and suggest that this effect might be associated with the inhibition of DNA repair

  16. Early childhood behavioral inhibition, adult psychopathology and the buffering effects of adolescent social networks: a twenty-year prospective study.

    Science.gov (United States)

    Frenkel, Tahl I; Fox, Nathan A; Pine, Daniel S; Walker, Olga L; Degnan, Kathryn A; Chronis-Tuscano, Andrea

    2015-10-01

    We examined whether the temperament of behavioral inhibition is a significant marker for psychopathology in early adulthood and whether such risk is buffered by peer social networks. Participants (N = 165) were from a prospective study spanning the first two decades of life. Temperament was characterized during infancy and early childhood. Extent of involvement in peer social networks was measured during adolescence, and psychopathology was assessed in early adulthood. Latent Class Analyses generated comprehensive variables at each of three study time-points. Regressions assessed (a) the direct effect of early behavioral inhibition on adult psychopathology (b) the moderating effect of adolescent involvement in social peer networks on the link between temperamental risk and adult psychopathology. Stable behavioral inhibition in early childhood was negatively associated with adult mental health (R(2 ) = .07, p = .005, β = -.26), specifically increasing risk for adult anxiety disorders (R(2) = .04, p = .037, β = .19). These temperament-pathology relations were significantly moderated by adolescent peer group social involvement and network size (Total R(2) = .13, p = .027, β = -.22). Temperament predicted heightened risk for adult anxiety when adolescent social involvement was low (p = .002, β = .43), but not when adolescent social involvement was high. Stable behavioral inhibition throughout early childhood is a risk factor for adult anxiety disorders and interacts with adolescent social involvement to moderate risk. This is the first study to demonstrate the critical role of adolescent involvement in socially active networks in moderating long-lasting temperamental risk over the course of two decades, thus informing prevention/intervention approaches. © 2015 Association for Child and Adolescent Mental Health.

  17. DNA-AuNP networks on cell membranes as a protective barrier to inhibit viral attachment, entry and budding.

    Science.gov (United States)

    Li, Chun Mei; Zheng, Lin Ling; Yang, Xiao Xi; Wan, Xiao Yan; Wu, Wen Bi; Zhen, Shu Jun; Li, Yuan Fang; Luo, Ling Fei; Huang, Cheng Zhi

    2016-01-01

    Viral infections have caused numerous diseases and deaths worldwide. Due to the emergence of new viruses and frequent virus variation, conventional antiviral strategies that directly target viral or cellular proteins are limited because of the specificity, drug resistance and rapid clearance from the human body. Therefore, developing safe and potent antiviral agents with activity against viral infection at multiple points in the viral life cycle remains a major challenge. In this report, we propose a new modality to inhibit viral infection by fabricating DNA conjugated gold nanoparticle (DNA-AuNP) networks on cell membranes as a protective barrier. The DNA-AuNPs networks were found, via a plaque formation assay and viral titers, to have potent antiviral ability and protect host cells from human respiratory syncytial virus (RSV). Confocal immunofluorescence image analysis showed 80 ± 3.8% of viral attachment, 91.1 ± 0.9% of viral entry and 87.9 ± 2.8% of viral budding were inhibited by the DNA-AuNP networks, which were further confirmed by real-time fluorescence imaging of the RSV infection process. The antiviral activity of the networks may be attributed to steric effects, the disruption of membrane glycoproteins and limited fusion of cell membrane bilayers, all of which play important roles in viral infection. Therefore, our results suggest that the DNA-AuNP networks have not only prophylactic effects to inhibit virus attachment and entry, but also therapeutic effects to inhibit viral budding and cell-to-cell spread. More importantly, this proof-of-principle study provides a pathway for the development of a universal, broad-spectrum antiviral therapy. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Effect of quercetin on radiosensitivity of human uterine cervix cancer HeLa cells

    International Nuclear Information System (INIS)

    Liang Xiaofang; Hong Chengjiao; Zhang Baoguo

    2009-01-01

    In order to investigate the effects of Quercetin on radiosensitivity of human Uterine Cervix Cancer HeLa cells, MTT assay and clonogenic assay were performed to evaluate the cytotoxicity of Quercetin on the cells. Clonogenic assay was used to observe its effects on the radiosensitivity of the cells. MTT result shows that the inhibition of Quercetin on the cells is in the dose-dependent and time-dependent. And the clonogenic assay result shows that the effect of Quercetin on HeLa cells can be divided into two parts, one for the inhibition of HeLa cells and another for the induction of HeLa cell death. The other clonogenic assay result also shows Quercetin can decrease clonogenic survival rate of HeLa cells exposed to X rays. The study shows Quercetin might enhance the radiosensitivity of the HeLa cell line. And it may provide a useful evaluation to combination of ionizing radiation and Quercetin for cancer patients. (authors)

  19. Differential radiosensitivity of seeds, seedlings and callus cultures of Petunia inflata

    International Nuclear Information System (INIS)

    Bapat, V.A.; Rao, P.S.

    1976-01-01

    A comparative study of the effects of γ-irradiation on seeds, seedlings and callus cultures of Petunia inflata showed striking differences in radiosensitivity as reflected in differences in mean fresh and dry weights, seedling height and morphology. Seeds subjected to low doses (4-6 kR) of irradiation showed stimulation of seedling height. Direct exposure of seedlings to high doses (10 kR) of irradiation caused inhibition in their development. Callus cultures, however, were more radioresistant compared to seeds and seedlings. Tissues grown on either an irradiated nutrient medium or on a medium in which sucrose alone had been irradiated, showed a marked inhibition in their growth potential

  20. The effect of anaesthesia on the radiosensitivity of rat intestine, foot skin and R-1 tumours

    International Nuclear Information System (INIS)

    Kal, H.B.; Gaiser, J.F.

    1980-01-01

    A comparison has been made of the effects of Nembutal (sodium pentobarbital) and Ethrane (2-chloro-1,1,2-trifluoroethyldifluoromethyl ether) anaesthesia on the radiation responses of rat intestine, foot skin and R-1 rhabdomyosarcoma. Single-dose experiments under Nembutal or short-lasting Ethrane anaesthesia resulted in equivalent radiosensitivities for the R-1 sarcoma and foot skin, whereas Ethrane induced radiosensitization in the intestine. In the Ethrane anaesthesia lasting 3 hours, and in the split-dose experiments, Ethrane inhibited repair of radiation-induced damage in the R-1 sarcoma and in the foot skin. It is therefore recommended that the use of Ethrane as an anaesthetic should be avoided in experiments designed to investigate repair of damage in fractionated studies or during protracted irradiation treatments. (UK)

  1. The effect of intra- and extracellular GSH depletion on aerobic radiosensitization in three cell lines

    International Nuclear Information System (INIS)

    Clark, E.P.; Epp, E.R.; Morse-Gaudio, M.; Biaglow, J.E.

    1985-01-01

    The effect of changes in the intra- and extracellular glutathione (GSH) concentrations on aerobic radiosensitization was studied in thee cell lines: CHO, V79 and A549. Intracellular GSH was metabolically depleted after the inhibition of GSH synthesis by buthionine sulfoximine (BSO) treatment of attached cell cultures. Extracellular GSH was controlled through the replacement of growth medium with a thiol-free salt solution and, where desired, by the exogenous addition of GSH. Each of the cell lines examined exhibited an enhanced aerobic radioresponse when the intracellular GSH was extensively depleted (GSH < 5% of control after 1.0 mM BSO/24 hr treatment) and the extracellular GSH concentration was zero. However, this enhanced radiosensitivity was eliminated by the addition of exogenous GSH, albeit at a high concentration (5 mM). Most interesting and as yet unexplained is the observation that GSH appears to affect restoration of the control radioresponse without increasing the intracellular GSH concentration

  2. Evaluation of a MTT assay in measurement of radiosensitizing effect

    International Nuclear Information System (INIS)

    Higuchi, Keiko; Mitsuhashi, Norio; Saitoh, Jun-ichi; Maebayashi, Katsuya; Sakurai, Hideyuki; Akimoto, Tetsuo; Niibe, Hideo

    1999-01-01

    The usefulness of a MTT assay by measuring the radiosensitizing effect of caffeine on rat yolk sac tumor cell line with a mutant-type p53 in vitro was evaluated. A rat yolk sac tumor cell line with a mutant-type p53, NMT-1R, was used in this study. The radiosensitivity of NMT-1R with or without caffeine was measured with a MTT assay. The results were compared with those by a clonogenic assay. Caffeine at a concentration of 2.0 mM which released radiation-induced G 2 block demonstrated a radiosensitizing effect, but caffeine at a concentration of 0.5 mM did not. The radiosensitizing effect of caffeine measured by a MTT assay correlated with that measured by a clonogenic assay. A MTT assay was useful to measure radiosensitivity and/or a radiosensitizing effect in vitro. (author)

  3. Gamma radiosensitivity of a common bean cultivar

    International Nuclear Information System (INIS)

    Colaco, W.; Martinez, C.R.

    1995-01-01

    A preliminary experiment was conducted to evaluate the radiosensitivity of common bean (Phaseolous vulgaris L.), cultivar to gamma rays from a 60 Co source. Sets of seeds (60 seed/sample) irradiated with 50, 100, 150, 200, and 250 Gy, were compared to a control without irradiation (0 Gy), under greenhouse conditions. The radiosensitivity was evaluated through seedling height reduction, determined at 15 days after emergence (DAE), and also through seedling survival, root length, and dry matter production of leaves, shoots and roots. Seedling height was significantly reduced for the treatments with 150 and 250 Gy, in relation to the control. The dose causing reduction of 50% seedling height was between 150 and 200 Gy. Survival rates corresponding to these doses, were, respectively, 85% and 60%. Root length and dry matter of leaves, shoots and roots, were inversely related to the doses. (author). 15 refs, 3 figs, 1 tab

  4. Effect of laser radiation on rat radiosensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Laprun, I.B.

    1979-03-01

    Quite a few experimental data have been obtained to date indicating that radioresistance of the organism is enhanced under the influence of electromagnetic emissions in the radiofrequency and optical ranges. But no studies were made of the possible radioprotective properties of coherent laser radiation. At the same time, it was demonstrated that the low-energy emission of optical quantum generators (lasers) in the red band stimulates the protective forces of the organism and accelerates regenerative processes; i.e., it induces effects that are the opposite of that of ionizing radiation. Moreover, it was recently demonstrated that there is activation of catalase, a radiosensitive enzyme that plays an important role in the metabolism of peroxide compounds, under the influence of lasers. For this reason, the effect of pre-exposure to laser beams on radiosensitivity of rats was tested.

  5. Predictive radiosensitivity tests in human lymphocytes

    International Nuclear Information System (INIS)

    Di Giorgio, Marina; Vallerga, Maria B.; Taja, Maria R.; Sardi, M.; Busto, E.; Mairal, L.; Roth, B.; Menendez, P.; Bonomi, M.

    2004-01-01

    Individual radiosensitivity is an inherent characteristic, associated with an abnormally increased reaction to ionising radiation of both the whole body and cells derived from body tissues. Human population is not uniform in its radiation sensitivity. Radiosensitive sub-groups exist, which would suffer an increased incidence of both deterministic and stochastic effects. Clinical studies have suggested that a large part of the spectrum of normal tissue reaction may be due to differences in individual radiosensitivity. The identification of such sub-groups should be relevant for radiation therapy and radiation protection purposes. It is suggested that DNA repair mechanisms are involved. Consequently, the characterization of DNA repair in lymphocytes through cytokinesis blocked micronucleus (MN) and alkaline single-cell microgel electrophoresis (comet) assays could be a suitable approache to evaluate individual radiosensitivity in vitro. The aims of this study were: 1) To assess the in vitro radiosensitivity of peripheral blood lymphocytes from two groups of cancer patients (prospectively and retrospectively studied), using MN and comet assays, in comparison with the clinical radiation reaction and 2) To test the predictive potential of both techniques for the identification of radiosensitivity sub-groups. 38 cancer patients receiving radiation therapy were enrolled in this study. 19 patients were evaluated prior, mid-way and on completion of treatment (prospective group) and 19 patients were evaluated about 6-18 month after radiotherapy (retrospective group). Cytogenetic data from the prospective group were analysed using a mathematical model to evaluate the attenuation of the cytogenetic effect as a function of the time between a single exposure and blood sampling, estimating a cytogenetic recovery factor k. In the retrospective group, blood samples were irradiated in vitro with 0 (control) or 2 Gy and evaluated using MN test. Cytogenetic data were analysed

  6. Radiosensitizers action on Iodine 131 therapeutical effect

    International Nuclear Information System (INIS)

    Agote, Marcos; Kreimann, Erica L.; Bocanera, Laura V.; Dagrosa, Maria A.; Juvenal, Guillermo J.; Pisarev, Mario A.

    1999-01-01

    Present studies were aimed to research the possible application of a radiosensitizer, nicotinamide, to increase the therapeutical effect of radioiodine. There were used goitrous and normal rats with growing dose of Iodine 131, with and without simultaneous treatment with nicotinamide. The obtained results show that the nicotinamide treatment importantly increases the thyroid radio destructive effect induced by radioiodine. Under these experimental conditions, nicotinamide induces to a significant increase of thyroid vascularisation, without changes in the proteins ADP-ribosylation activity. These results show, for the first time, the radiosensitizer effect of nicotinamide in front of Iodine 131 and give the possibility of using it in the treatment of hyperthyroid or thyroid difference cancer patients. (author)

  7. Radiosensitivity study of salmonella enteritidis in chickens

    International Nuclear Information System (INIS)

    Fernandez Gianotti, Tomas

    1997-01-01

    One of the applications of ionizing radiations in food is the inactivation of vegetative phatogenic bacteria (radicidation) such as Salmonella, Shigella, Campylobacter, Vibro and Listeria. These bacteria are associated with the diseases transmitted by food (ETA). Fresh and frozen farmyard fowls can be contaminated with pathogenic microorganisms, between them Salmonella. In Argentine, between years 1987-1990, Salmonella enteritidis was the main cause of salmonellosis. In food irradiation, with the aim of improving and assuring its hygienic quality, it is important to know the radiosensitivity of microorganisms to be inactivated. Inactivation of a determined microorganism shall depend, between others factors, of the species, strain, number and of the irradiation conditions (temperature, media, etc.). D 10 value is a very useful data in order to compare radiosensitivities between the microorganisms and the influence of different factors in their sensitivities. In this paper, it was determined the sensitivity to the gamma radiation of Salmonella enteritidis in fresh and frozen chickens

  8. Wnt activation affects proliferation, invasiveness and radiosensitivity in medulloblastoma.

    Science.gov (United States)

    Salaroli, Roberta; Ronchi, Alice; Buttarelli, Francesca Romana; Cortesi, Filippo; Marchese, Valeria; Della Bella, Elena; Renna, Cristiano; Baldi, Caterina; Giangaspero, Felice; Cenacchi, Giovanna

    2015-01-01

    Medulloblastomas (MBs) associated with the Wnt activation represent a subgroup with a favorable prognosis, but it remains unclear whether Wnt activation confers a less aggressive phenotype and/or enhances radiosensitivity. To investigate this issue, we evaluated the biological behavior of an MB cell line, UW228-1, stably transfected with human β-catenin cDNA encoding a nondegradable form of β-catenin (UW-B) in standard culture conditions and after radiation treatment. We evaluated the expression, transcriptional activity, and localization of β-catenin in the stably transfected cells using immunofluorescence and WB. We performed morphological analysis using light and electron microscopy. We then analyzed changes in the invasiveness, growth, and mortality in standard culture conditions and after radiation. We demonstrated that (A) Wnt activation inhibited 97 % of the invasion capability of the cells, (B) the growth of the UW-B cells was statistically significantly lower than that of all the other control cells (p < 0.01), (C) the mortality of irradiated UW-B cells was statistically significantly higher than that of the controls and their nonirradiated counterparts (p < 0.05), and (D) morphological features of neuronal differentiation were observed in the Wnt-activated cells. In tissue samples, the Ki-67 labeling index (LI) was lower in β-catenin-positive samples compared to non-β-catenin positive ones. The Ki-67 LI median (LI = 40) of the nuclear β-catenin-positive tumor samples was lower than that of non-nuclear β-catenin-positive samples (LI = 50), but the difference was not statistically significant. Overall, our data suggest that activation of the Wnt pathway reduces the proliferation and invasion of MBs and increases the tumor's radiosensitivity.

  9. Radiosensitivity of primary cultured fish cells with different ploidy

    International Nuclear Information System (INIS)

    Mitani, Hiroshi; Egami, Nobuo; Kobayashi, Hiromu.

    1986-01-01

    The radiosensitivity of primary cultured goldfish cells (Carassius auratus) was investigated by colony formation assay. The radiosensitivity of cells from two varieties of goldfish, which show different sensitivity to lethal effect of ionizing radiation in vivo, was almost identical. Primary cultured cells from diploid, triploid and tetraploid fish retained their DNA content as measured by microfluorometry, and the nuclear size increases as ploidy increases. However, radiosensitivity was not related to ploidy. (author)

  10. DNA repair , cell repair and radiosensitivity

    International Nuclear Information System (INIS)

    Zhestyanikov, V.D.

    1983-01-01

    Data obtained in laboratory of radiation cytology and literature data testifying to a considerable role of DNA repair in cell sensitivity to radiation and chemical DNA-tropic agents have been considered. Data pointing to the probability of contribution of inducible repair of DNA into plant cells sensitivity to X-rays are obtained. Certain violations of DNA repair do not result in the increase of radiosensitivity. It is assumed that in the cases unknown mechanisms of DNA repair operate

  11. Radiosensitivity of red flour beetle tribolium castaneum

    International Nuclear Information System (INIS)

    Sattar, A.; Khattak, S.; Hamed, M.

    1992-07-01

    In this report radiosensitivity of red beetle has been discussed. Red flour beetle is the most injurious pest causing great losses to stored grain. Radiation is one of the best tools of insect control. Different radiation doses (50 to 200 krads) were employed for different age groups from 1 to 60 days. It is concluded from these results that 200 krad radiation dose caused 100% mortality in red beetle in all age group. (A.B.)

  12. Nimotuzumab promotes radiosensitivity of EGFR-overexpression esophageal squamous cell carcinoma cells by upregulating IGFBP-3

    Directory of Open Access Journals (Sweden)

    Zhao Lei

    2012-12-01

    Full Text Available Abstract Background Epidermal growth factor receptor (EGFR is suggested to predict the radiosensitivity and/or prognosis of human esophageal squamous cell carcinoma (ESCC. The objective of this study was to investigate the efficacy of Nimotuzumab (an anti-EGFR monoclonal antibody on ESCC radiotherapy (RT and underlying mechanisms. Methods Nimotuzumab was administrated to 2 ESCC cell lines KYSE30 and TE-1 treated with RT. Cell growth, colony formation and apoptosis were used to measure anti-proliferation effects. The method of RNA interference was used to investigate the role of insulin-like growth factor binding protein-3 (IGFBP-3 in ESCC cells radiosensitivity treated with Nimotuzumab. In vivo effect of Nimotuzumab on ESCC radiotherapy was done using a mouse xenograft model. Results Nimotuzumab enhanced radiation response of KYSE30 cells (with high EGFR expression in vitro, as evidenced by increased radiation-inhibited cell growth and colony formation and radiation-mediated apoptosis. Mechanism study revealed that Nimotuzumab inhibited phosphorylated EGFR (p-EGFR induced by EGF in KYSE30 cells. In addition, knockdown of IGFBP-3 by short hairpin RNA significantly reduced KYSE30 cells radiosensitivity (PP>0.05. In KYSE30 cell xenografts, Nimotuzumab combined with radiation led to significant tumor growth delay, compared with that of radiation alone (P=0.029, and also with IGFBP-3 up-regulation in tumor tissue. Conclusions Nimotuzumab could enhance the RT effect of ESCC cells with a functional active EGFR pathway. In particular, the increased ESCC radiosensitivity by Nimotuzumab might be dependent on the up-regulation of IGFBP-3 through EGFR-dependent pathway.

  13. Clinical studies on radiosensitization of cervical cancer by cisplatinum

    International Nuclear Information System (INIS)

    Yu Shiying; Chen Yuan; Xu Zhiqiang

    1993-01-01

    A prospective randomized clinical trial on the radiosensitizing effect of cisplatinum was carried out in 60 patients with cervical cancer, of whom 30 were given cisplatinum in combination with radiotherapy (radiosensitizing group) and the remaining 30 radiotherapy alone (control group). The results showed that the length of time of immediate CR and PR was shorter in the radiosensitizing group than in the control group. The sensitive enhancement ratio was 1.846. No toxicity was observed in the radiosensitizing group, and the treatment was well tolerated by the patients

  14. Catecholamines of the body tissues and radiosensitivity of rodents

    Energy Technology Data Exchange (ETDEWEB)

    Grayevskaya, V M; Zolotariova, N N [AN SSSR, Moscow. Inst. Morfologii Zhivotnykh

    1975-01-01

    Various species of rodents are distinguished by their radiosensitivity (increasing): bank vole < Wistar rat < wild mouse < CC/sub 57/Br mouse < golden hamster < BALB mouse < guinea pig. There is a positive correlation between radiosensitivity of these species and catecholamines content in the adrenals, urea and blood; and negative correlation between radiosensitivity and adrenaline and noradrenaline concentrations in liver and spleen cells. Presumable causes of this correlation, and the possibility of application of the index under study for predicting the organism radiosensitivity and forecasting the outcome of radiation damage are discussed.

  15. Catecholamines of the body tissues and radiosensitivity of rodents

    International Nuclear Information System (INIS)

    Grayevskaya, V.M.; Zolotariova, N.N.

    1975-01-01

    Various species of rodents are distinguished by their radiosensitivity (increasing): bank vole 57 Br mouse < golden hamster < BALB mouse < guinea pig. There is a positive correlation between radiosensitivity of these species and catecholamines content in the adrenals, urea and blood; and negative correlation between radiosensitivity and adrenaline and noradrenaline concentrations in liver and spleen cells. Presumable causes of this correlation, and the possibility of application of the index under study for predicting the organism radiosensitivity and forecasting the outcome of radiation damage are discussed

  16. Stattic Enhances Radiosensitivity and Reduces Radio-Induced Migration and Invasion in HCC Cell Lines through an Apoptosis Pathway

    Directory of Open Access Journals (Sweden)

    Gang Xu

    2017-01-01

    Full Text Available Purpose. Signal transducer and activator of transcription factor 3 (STAT3 is involved in tumorigenesis, development, and radioresistance of many solid tumors. The aim of this study is to investigate the effects of stattic (an inhibitor of STAT3 on the radiosensitivity and radio-induced migration and invasion ability in hepatocellular carcinoma (HCC cell lines. Methods. HCC cells were treated with stattic, and cell survival rate was analyzed through CCK-8 assay. Radiosensitivity was evaluated using cloning formation analysis; STAT3, p-STAT3, and apoptosis related proteins were detected by western blot. Radio-induced migration and invasion ability in HCC cells were analyzed by wound-healing assay and transwell test. Results. Stattic inhibits the expression of p-STAT3 and reduces cell survival in a dose-dependent manner in HCC cell lines, and the IC50 values for Hep G2, Bel-7402, and SMMC-7721 are 2.94 μM, 2.5 μM, and 5.1 μM, respectively. Cloning formation analysis shows that stattic enhances the radiosensitivity of HCC cells. Wound-healing assay and transwell test show that stattic inhibits radio-induced migration and invasion. Further study indicates that stattic promotes radio-induce apoptosis through regulating the expression of apoptosis related proteins in HCC cells. Conclusion. Stattic enhances radiosensitivity and reduces radio-induced migration and invasion ability in HCC cells probably through apoptosis pathway.

  17. Understanding the radiosensitivity of hematopoietic stem cells through CDNA micro-arrays profiling

    Energy Technology Data Exchange (ETDEWEB)

    Pawlik, A.; Cebo, Ch.; Vaigot, P.; Tronik-Le Roux, D. [Evry Univ., Lab. de Genomique et Radiobiologie de l' Hematopoiese, Service de Genomique Fonctionnelle, CEA, 91 (France)

    2006-07-01

    individually, since a large percentage of the identified genes have not been yet attributed to a particular function. To determine whether expression modulations of these genes could be associated with changes in the cell radiosensitivity, we have constructed vectors containing either cDNA s encoding four transcription factors or specific siRNA. Transfections in different cell lines are currently performed to assess whether overexpression or inhibition o f these factors might modify the radiosensitivity of the cell. To determine whether the in vivo transcriptional changes in gene expression triggered by ionizing radiation exposure were dependent on the microenvironment, the effect of IR exposure was monitored in the murine E.M.L. cell line. These cells were defined as possessing a Sca 'B220{sup -} Lin{sup lo} stem-like phenotype and can be potentially differentiated onto both lymphoid and myeloid lineages. Similarities of the in vivo and in vitro responses might be considered mostly as cell autonomous. Altogether this approach has the potential for unraveling molecular networks and finding novel and specific actors participating to the early response o f hematopoietic cells to radiation exposure. The outcome of this research might lead to the identification of molecules that ultimately modify the radiosensitivity of a cell and facilitate the derivation of clinically useful targets for rational therapeutic decisions. (N.C.)

  18. Radiosensitivity of grapevines. Empirical modelling of the radiosensitivity of some clones to x-ray irradiation. Pt. 1

    International Nuclear Information System (INIS)

    Koeroesi, F.; Jezierska-Szabo, E.

    1999-01-01

    Empirical and formal (Poisson) models were utilized, applying experimental growth data to characterize the radiosensitivity of six grapevine clones to X-ray irradiation. According to the radiosensitivity constants (k), target numbers (n) and volumes, GR 37 doses and energy deposition, the following radiosensitivity order has been found for various vine brands: Chardonnay clone type < Harslevelue K. 9 < Koevidinka K. 8 < Muscat Ottonel clone type < Irsai Oliver K. 11 < Cabernet Sauvignon E. 153. The model can be expanded to describe the radiosensitivity of other plant species and varieties, and also the efficiency of various radioprotecting agents and conditions. (author)

  19. Increased catalase activity by all-trans retinoic acid and its effect on radiosensitivity in rat glioma cells

    International Nuclear Information System (INIS)

    Jin, Hua; Jeon, Ha Yeun; Park, Woo Yoon; Kim, Won Dong; Ahn, Hee Yul; Yu, Jae Ran

    2005-01-01

    It has been reported that all-trans retinoic acid (ATRA) can inhibit glioma growing in vitro. However, clinical trials with ATRA alone in gliomas revealed modest results. ATRA has been shown to increase radiosensitivity in other tumor types, so combining radiation and ATRA would be one of alternatives to increase therapeutic efficacy in malignant gliomas. Thus, we intended to know the role of catalase, which is induced by ATRA, for radiosensitivity. If radiation-reduced reactive oxygen species (ROS) is removed by catalase, the effect of radiation will be reduced. A rat glioma cell line (36B10) was used for this study. The change of catalase activity and radiosensitivity by ATRA, with or without 3-amino-1, 2, 4-triazole (ATZ), a chemical inhibitor of catalase were measured. Catalase activity was measured by the decomposition of H 2 O 2 spectrophotometrically. Radiosensitivity was measured with clonogenic assay. Also ROS was measured using a 2, 7-dichlorofluores-cein diacetate spectrophotometrically. When 36B10 cells were exposed to 10, 25 and 50 μ M of ATRA for 48 h, the expression of catalase activity were increased with increasing concentration and incubation time of ATRA. Catalase activity was decreased with increasing the concentration of AT (1, 10 mM) dose-dependently. ROS was increased with ATRA and it was augmented with the combination of ATRA and radiation. ATZ decreased ROS production and increased cell survival in combination of ATRA and radiation despite the reduction of catalase. The increase of ROS is one of the reasons for the increased radiosensitivity in combination with ATRA. The catalase that is induced by ATRA doesn't decrease ROS production and radiosensitivity

  20. Radio-sensitization of WRN helicase deficient cancer cells by targeting homologous recombination pathway

    International Nuclear Information System (INIS)

    Gupta, Pooja; Saha, Bhaskar; Patro, Birija Sankar; Chattopadhyay, Subrata

    2016-01-01

    Ionizing radiation (IR) induced DNA double-strand breaks (DSBs) are primarily repaired by non-homologous end joining (NHEJ). However, it is well established that a subset DSBs which are accumulated in IR-induced G2 phase are dependent on homologous recombination (HR). DNA repair deficient tumor cells have been shown to accumulate high levels of DNA damage. Consequently, these cells become hyperdependent on DNA damage response pathways, including the CHK1-kinase-mediated HR-repair. These observations suggest that DNA repair deficient tumors should exhibit increased radio-sensitivity under HR inhibition. Genetic defects leading to functional loss of werner (WRN) protein is associated with genomic instability and increased cancer incidence. WRN function is known to be abrogated in several human cancer cells due to hypermethylation of CpGisland-promoter and transcriptional silencing of WRN gene. In the current investigation, using isogenic pairs of cell lines differing only in the WRN function, we showed that WRN-deficient cell lines were hyper-radiosensitive to CHK1 pharmacologic inhibition. Here, we found that unrepaired DSB was drastically increased in WRN-deficient cells vis-à-vis WRN-proficient cells in response to IR and CHK1 inhibitor (CHK1i). Our results revealed a marginal role of NHEJ pathway accountable for the radio-sensitivity of WRN-deficient cells. Interestingly, silencing CTIP, a HR protein required for RAD51 loading, significantly abrogated the CHK1i-mediated radiosensitivity in WRN-deficient cells. Silencing of WRN or CTIP individually led to no significant difference in the extent of DNA end resection, as required during HR pathway. Imperatively, our results revealed that WRN and CTIP together play a complementary role in executing DNA end resection during HR-mediated repair of IR induced DSBs. Altogether, our data indicated that inhibition of IR-induced HR pathway at RAD51 loading, but not at DSB end resection, make the WRN-deficient cancer cells

  1. Effect of postirradiation anoxia on radiosensitivity of lymphocytes

    International Nuclear Information System (INIS)

    Schrek, R.

    1976-01-01

    Radiosensitivity was measured by viable-lymphocyte counts and by uridine uptake. The viability of the lymphocytes was based on morphologic characteristics visualized by phase contrast microscopy of the cells in a special slide chamber. Low doses of x rays (10 to 1000 R) and incubation at 37 0 C killed lymphocytes in interphase with the production of pyknotic nuclei (nuclear death), and large doses (6000 R) produced nuclei with clear nucleoplasm (cytoplasmic death). Nuclear, but not cytoplasmic, death was inhibited by incubation of the irradiated cells at 27 0 C. Postirradiation anoxia had no effect on development of the nuclear and cytoplasmic death of lymphocytes irradiated with 100 to 6000 R. Anoxia had no effect on the early response of lymphocytes to phytohemagglutinin (PHA) [increase in ribonucleic acid (RNA) and protein synthesis] but inhibited completely the late effects [increase in deoxyribonucleic acid (DNA) synthesis and transformation into lymphoblastoid cells]. The PHA caused relative radioresistance of lymphocytes under aerobic conditions and, to a lesser extent, under anaerobic conditions. The slight radioresistance induced by PHA in anoxic lymphocytes apparently did not depend on an increase in DNA synthesis or on the transformation to lymphoblastoid cells

  2. Enhanced Radiosensitization Effect of Curcumin Delivered by PVP-PCL Nanoparticle in Lung Cancer

    Directory of Open Access Journals (Sweden)

    Cuixia Wen

    2017-01-01

    Full Text Available Curcumin, the principal polyphenolic curcuminoid, has been reported in numerous studies for its antitumor effect in a series of cancers. It is also reported that curcumin possesses radiosensitization effect in some cancers. However, the poor solubility and unsatisfied bioavailability of curcumin significantly undermine its potential application. Here we prepared curcumin loaded nanoparticles by employing PVP-PCL as drug carrier. Characterization studies indicated the satisfied drug loading efficiency and a sustained in vitro release pattern. Quantification uptake study showed that the uptake efficiency of Cum-NPs by lung cancer cells was time- and dose-dependent. In vitro anticancer study demonstrated the superior cytotoxic effect of Cum-NPs with stronger apoptotic induction over free Cum. Most importantly, there is almost no report on the radiosensitization effect of curcumin loaded nanoparticles. Here, Cum-NPs led to more inhibition of the colony forming ability of A549 cells as compared to the equivalent concentration of free Cum as shown in clonogenic assay. Furthermore, Cum-NPs are much more effective in enhancing the tumor growth inhibitory effect of radiation therapy in a A549 xenograft model. Therefore, results from the current study seem to be the first report on the radiosensitization effect of Cum-NPs and paved the way for a curcumin nanodrug delivery system as a potential radiation adjuvant.

  3. Validation of a radiosensitivity molecular signature in breast cancer

    NARCIS (Netherlands)

    S.A. Eschrich (Steven); C. Fulp (Carl); Y. Pawitan (Yudi); J.A. Foekens (John); M. Smid (Marcel); J.W.M. Martens (John); M. Echevarria (Michelle); P.S. Kamath (Patrick); J.-H. Lee (Ji-Hyun); E.E. Harris (Eleanor); J. Bergh (Jonas); J.F. Torres-Roca (Javier)

    2012-01-01

    textabstractPurpose: Previously, we developed a radiosensitivity molecular signature [radiosensitivity index (RSI)] that was clinically validated in 3 independent datasets (rectal, esophageal, and head and neck) in 118 patients. Here, we test RSI in radiotherapy (RT)-treated breast cancer patients.

  4. Modern concepts for basic radiobiological factors characterizing tumor tissue radiosensitivity

    International Nuclear Information System (INIS)

    Gocheva, L.; Sergieva, K.

    2002-01-01

    Traditionally radiotherapy is prescribed at doses consistent with the expected therapeutic response and tolerance of tumor and normal tissues without consideration to individual differences in radiosensitivity. However, the basic radiobiological knowledge and clinical experience along this line point to significant variations in the observed therapeutic results. It has been established that cells and tissues under experimental and clinical conditions manifest a wide spectrum of individual radiosensitivity. The aim of this survey is to outline the current concepts for the basic radiobiological factors influencing tumor radiosensitivity. A thorough discussion is done of the essence, mechanisms of action, methods of determination and measurement, and effect on the prognosis in patients with malignant diseases of a number of radiobiological factors, such as: tumor-cell proliferation, apoptosis, tumor hypoxia and neovascularization. Although the knowledge of the mechanisms of radiosensitivity is constantly expanding, its clinical implementation is still rather limited. The true role of radiosensitivity in predicting the therapeutic response should be more accurately defined. (authors)

  5. Chromosomal radiosensitivity in patients with multiple sclerosis

    International Nuclear Information System (INIS)

    Milenkova, Maria; Milanov, Ivan; Kmetska, Ksenia; Deleva, Sofia; Popova, Ljubomira; Hadjidekova, Valeria; Groudeva, Violeta; Hadjidekova, Savina; Domínguez, Inmaculada

    2013-01-01

    Highlights: • We studied radiosensitivity to in vitro γ-irradiated lymphocytes from MS patients. • Immunotherapy in RRMS patients reduced the yield of radiation induced MN. • The group of treated RRMS accounts for the low radiosensitivity in MS patients. • Spontaneous yield of MN was similar in treated and untreated RRMS patients. - Abstract: Multiple sclerosis is a clinically heterogeneous autoimmune disease leading to severe neurological disability. Although during the last years many disease-modifying agents as treatment options for multiple sclerosis have been made available, their mechanisms of action are still not fully determined. In the present study radiosensitivity in lymphocytes of patients with relapsing–remitting multiple sclerosis, secondary progressive multiple sclerosis and healthy controls was investigated. Whole blood cultures from multiple sclerosis patients and healthy controls were used to analyze the spontaneous and radiation-induced micronuclei in binucleated lymphocytes. A subgroup of patients with relapsing–remitting multiple sclerosis was treated with immunomodulatory agents, interferon β or glatiramer acetate. The secondary progressive multiple sclerosis patients group was not receiving any treatment. Our results reveal that the basal DNA damage was not different between relapsing–remitting and secondary progressive multiple sclerosis patients, and healthy controls. No differences between gamma-irradiation induced micronuclei frequencies in binucleated cells from relapsing–remitting and secondary progressive multiple sclerosis patients, and healthy controls were found either. Nevertheless, when we compared the radiation induced DNA damage in binucleated cells from healthy individuals with the whole group of patients, a reduction in the frequency of micronuclei was obtained in the patients group. Induced micronuclei yield was significantly lower in the irradiated samples from treated relapsing–remitting multiple

  6. Taxonomic and developmental aspects of radiosensitivity

    International Nuclear Information System (INIS)

    Harrison, F.L.; Anderson, S.L.

    1996-11-01

    Considerable information is available on the effects of radioactivity on adult and early life stages of organisms. The preponderance of data is on mortality after a single irradiation with relatively high doses. Unfortunately, because experiments were carried out under different conditions and for different time periods, the validity of comparing the results from different laxonomic groups is questionable. In general, the conclusions are that there is a relationship (1) between radioresistance to high doses of acute radiation and taxonomy of the organism, primitive forms being more radioresistant than complex vertebrates and (2) between radiosensitivity and developmental stage, early life stages being more sensitive than later stages. The first conclusion may be related to the capability of the organism to repopulate cells and to differentiate and redifferentiate them; the second to the rate of cellular division and to the degree of differentiation. In question, however, is the relevance of the responses from high levels of acute radiation to that of the responses to long-term exposure to low levels of radiation, which are ecologically of more interest. Data from studies of the effects of acute and chronic exposure on development of gametes and zygotes indicate that, for some fishes and invertebrates, responses at the cellular and molecular levels show effect levels comparable to those observed in some mammals. Acute doses between 0,05 and 0.5Cy and dose rates between 0.02 to 0.2mCy/h appear to define critical ranges in which detrimental effects on fertility are first observed in a variety of radiosensitive organisms. To better understand inherent radiosensitivity, we need more information on the ability of cells to repopulate and differentiate and to prevent or repair damage to biological critical molecules, such as DNA, because these factors may alter significantly organisms'' responses to radiation

  7. Chromosomal radiosensitivity in patients with multiple sclerosis

    Energy Technology Data Exchange (ETDEWEB)

    Milenkova, Maria; Milanov, Ivan; Kmetska, Ksenia [III Neurological Clinic, University Hospital Saint Naum, Sofia (Bulgaria); Deleva, Sofia; Popova, Ljubomira; Hadjidekova, Valeria [Laboratory of Radiation Genetics, NCRRP, Sofia (Bulgaria); Groudeva, Violeta [Department of Diagnostic Imaging, University Hospital St. Ekaterina, Sofia (Bulgaria); Hadjidekova, Savina [Department of Medical Genetics, Medical University, Sofia (Bulgaria); Domínguez, Inmaculada, E-mail: idomin@us.es [Department of Cell Biology, Faculty of Biology, University of Seville, Avda. Reina Mercedes 6, 41012 (Spain)

    2013-09-15

    Highlights: • We studied radiosensitivity to in vitro γ-irradiated lymphocytes from MS patients. • Immunotherapy in RRMS patients reduced the yield of radiation induced MN. • The group of treated RRMS accounts for the low radiosensitivity in MS patients. • Spontaneous yield of MN was similar in treated and untreated RRMS patients. - Abstract: Multiple sclerosis is a clinically heterogeneous autoimmune disease leading to severe neurological disability. Although during the last years many disease-modifying agents as treatment options for multiple sclerosis have been made available, their mechanisms of action are still not fully determined. In the present study radiosensitivity in lymphocytes of patients with relapsing–remitting multiple sclerosis, secondary progressive multiple sclerosis and healthy controls was investigated. Whole blood cultures from multiple sclerosis patients and healthy controls were used to analyze the spontaneous and radiation-induced micronuclei in binucleated lymphocytes. A subgroup of patients with relapsing–remitting multiple sclerosis was treated with immunomodulatory agents, interferon β or glatiramer acetate. The secondary progressive multiple sclerosis patients group was not receiving any treatment. Our results reveal that the basal DNA damage was not different between relapsing–remitting and secondary progressive multiple sclerosis patients, and healthy controls. No differences between gamma-irradiation induced micronuclei frequencies in binucleated cells from relapsing–remitting and secondary progressive multiple sclerosis patients, and healthy controls were found either. Nevertheless, when we compared the radiation induced DNA damage in binucleated cells from healthy individuals with the whole group of patients, a reduction in the frequency of micronuclei was obtained in the patients group. Induced micronuclei yield was significantly lower in the irradiated samples from treated relapsing–remitting multiple

  8. Taxonomic and developmental aspects of radiosensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, F.L. [Lawrence Livermore National Lab., CA (United States); Anderson, S.L. [Lawrence Berkeley National Lab., CA (United States)

    1996-11-01

    Considerable information is available on the effects of radioactivity on adult and early life stages of organisms. The preponderance of data is on mortality after a single irradiation with relatively high doses. Unfortunately, because experiments were carried out under different conditions and for different time periods, the validity of comparing the results from different laxonomic groups is questionable. In general, the conclusions are that there is a relationship (1) between radioresistance to high doses of acute radiation and taxonomy of the organism, primitive forms being more radioresistant than complex vertebrates and (2) between radiosensitivity and developmental stage, early life stages being more sensitive than later stages. The first conclusion may be related to the capability of the organism to repopulate cells and to differentiate and redifferentiate them; the second to the rate of cellular division and to the degree of differentiation. In question, however, is the relevance of the responses from high levels of acute radiation to that of the responses to long-term exposure to low levels of radiation, which are ecologically of more interest. Data from studies of the effects of acute and chronic exposure on development of gametes and zygotes indicate that, for some fishes and invertebrates, responses at the cellular and molecular levels show effect levels comparable to those observed in some mammals. Acute doses between 0,05 and 0.5Cy and dose rates between 0.02 to 0.2mCy/h appear to define critical ranges in which detrimental effects on fertility are first observed in a variety of radiosensitive organisms. To better understand inherent radiosensitivity, we need more information on the ability of cells to repopulate and differentiate and to prevent or repair damage to biological critical molecules, such as DNA, because these factors may alter significantly organisms` responses to radiation.

  9. The toxic effects, GSH depletion and radiosensitivity by BSO on retinoblastoma

    International Nuclear Information System (INIS)

    Xianjin Yi; Li Ding; Yizun Jin; Chuo Ni; Wenji Wang

    1994-01-01

    Retinoblastoma is the most common intraocular malignant tumor in children. Previous investigations have reported that buthionine sulfoximine (BSO) can deplete intracellular glutathione (GSH) by specific inhibition and increase cellular radiosensitivity. The toxic effects, GSH depletion and radiosensitivity effects of BSO on retinoblastoma cells are reported in this paper. GSH content of retinoblastoma cell lines Y-79, So-Rb50 and retinoblastoma xenograft is 2.7 ± 1.3 X 1.0 -12 mmol/cell, 1.4 ± 0.2 X 1.0 -12 mmol/cell, and 2.8 ± 1.2 μmol/g, respectively. The ID 50 of BSO on Y-79 and So-Rb50 in air for 3 h exposure is 2.5 mM and 0.2 mM, respectively. GSH depletion by 0.1 mM BSO for 24 h on Y-79 cells and 0.01 mM BSO for 24 h on So-Rb50 cells is 16.35%, and 4.7% of control. GSH depletion in tumor and other organ tissues in retinoblastoma-bearing nude mice after BSO administration is differential. GSH depletion after BSO exposure in Y-79 cells in vitro decreases the Do value of retinoblastoma cells. The SER of 0.01 mM and 0.05 mM BSO for 24 h under hypoxic conditions is 1.21 and 1.36, respectively. Based on these observations, the authors conclude that BSO toxicity on retinoblastoma cells depends on the characteristics of the cell line and that BSO can increase hypoxic retinoblastoma cells' radiosensitivity in vitro. Further study of BSO radiosensitization on retinoblastoma in vivo using nude mouse xenografts is needed. 25 refs., 3 figs., 3 tabs

  10. The toxic effects, GSH depletion and radiosensitivity by BSO on retinoblastoma

    International Nuclear Information System (INIS)

    Yi Xianjin; Ni Chuo; Wang Wengi; Li Ding; Jin Yizun

    1993-01-01

    Retinoblastoma is the most common intraocular malignant tumor in children. Previous investigations have reported that buthionine sulfoximine (BSO) can deplete intracellular glutathione (GSH) by the specific inhibition and increase cellular radiosensitivity. The toxic effects, GSH depletion and radiosensitivity of BSO on retinoblastoma were reported. GSH content of retinoblastoma cell lines Y-79, So-Rb50 and retinoblastoma xenograft is (2.7 +- 1.3) x 10 -12 mmol/cell, (1.4 +- 0.2) x 10 -12 mmol/cell, and 2.8 +- 1.2 μmol/g respectively. The ID50 of BSO on Y-79 and So-Rb50 in air for 3h exposure is 2.5 mM and 0.2 mM respectively. GSH depletion by 0.1 mM BSO for 24h on Y-79 cells and 0.01 mM BSO for 24 h on So-Rb50 cells is 16.35%, and 4.7% of control. GSH depletion in tumor and other organ tissues in retinoblastoma bearing nude mice after BSO administration is differential. BSH depletion after BSO exposure in Y-79 cells in vitro decrease the D 0 value of retinoblastoma cells. The SER of 0.01 mM and 0.05 mM BSO for 24 h under the hypoxic condition is 1.21 and 1.36 respectively. Based on these observations, the authors conclude that BSO toxicity on retinoblastoma cells depends on the characteristics of cell line and BSO can increase hypoxic retinoblastoma cells radiosensitivity in vitro. Further study of BSO radiosensitization on retinoblastoma in vivo using nude mouse xenograft is needed

  11. Chemical radiosensitizers with special reference to metronidazole

    International Nuclear Information System (INIS)

    Sharma, R.; Purohit, O.P.; Nair, C.R.; Dutta, T.K.

    1982-01-01

    An attempt at rationalisation of drug dose schedule for a radiosensitizer in a cancer clinic is attempted. A prospective analysis of tissue tolerance, response data and complications of the two groups of patients (treated by oral and high intermittent rectal routes) was made with matched control. The study group has definite use of metronidazole. It is further highlighted that there is an additional advantage of the rectal administration route of the drug as compared to that of the oral route. This is a preliminary communication. (author)

  12. Radiosensitization of thymidine in deaerated aqueous solution

    International Nuclear Information System (INIS)

    Berger, Maurice.

    1982-09-01

    This work investigates the mode of action of various radiosensitizing agents on the radio-induced degradation of thymidine in deaerated aqueous solution. A special effort was devoted to the separation of addition products formed by one of these substances (a stable nitroxide radical: TAN) with the radio-induced neutral radicals of thymidine. The complex mixture of different diastereoisomers resulting from the covalent addition of the TAN molecule on the thymidine carbons C (5) or C (6) was resolved by HPLC. The structural determination of these adducts (absolute configuration) was achieved by various spectroscopic techniques and specific chemical syntheses. A conformational study has been undertaken [fr

  13. Analysis of mice radiosensitivity depending on age

    International Nuclear Information System (INIS)

    Bogatyrev, A.V.; Timoshenko, S.I.; Nikanorova, N.G.; Sverdlov, A.G.

    1979-01-01

    In order to elucidate mechanisms of age variations in radiosensitivity of mice a study was made of the sensitivity of in vitro irradiated bone marrow stem cells, taken from animals of different age, and postradiation recovery of leukocyte content of peripheral blood and cellularity of bone marrow and spleen. Using the method of spleen colonies similar affections were revealed in bone marrow cells of animals of different age. The degree of recovery of the hemopoietic cell pool was significantly lower in newborn mice than in adults after exposure to a dose (LDsub(50/30)) equally effective with respect to mortality

  14. Radiosensitivity study in rice (Oriza Sativa Lin.)

    International Nuclear Information System (INIS)

    Gonzalez, M.; Santana, N.; Diaz, R.

    1987-01-01

    Four rice varieties (J-104, Amistad-82, 6066 and IR-1529) were irradiated at doses of 10,15,20,25,30,35,40,45,50 and 55 Krad of gamma rays so as to determine radiosensitivity curves for each of the varieties for the following factors; seed germination percentage; survival percentage; height of the plant; length of roots. It was determined that IR-1529 variety is the one with the highest sensitivity and that radiations over 35 Krad should not be used for none of the varieties above mentioned

  15. AT-406, an IAP inhibitor, activates apoptosis and induces radiosensitization of normoxic and hypoxic cervical cancer cells.

    Science.gov (United States)

    Lu, Jing; Qin, Qin; Zhan, Liang-Liang; Liu, Jia; Zhu, Hong-Cheng; Yang, Xi; Zhang, Chi; Xu, Li-Ping; Liu, Zhe-Ming; Wang, Di; Cui, He-Qing; Meng, Ciu-Ciu; Cai, Jing; Cheng, Hong-Yan; Sun, Xin-Chen

    2014-01-01

    IAP antagonists increased the antitumor efficacy of X-irradiation in some types of cancers, but their effects on hypoxic cancer cells remain unclarified. We aims to investigate the radiosensitizing effect of an IAP inhibitor AT-406 on cervical cancer cell lines under both normoxia and hypoxia conditions. Hela and Siha cells were treated to investigate the effects of drug administration on cell proliferation, apoptosis, and radiosensitivity. Western blot analysis was used to determine the role of AT-406 in inhibition of IAPs. The pathway of apoptosis was characterized by caspases activity assay. AT-406 potently sensitized Hela cells but not Siha cells to radiation under normoxia. Notably, the radiosensitizing effect of AT-406 on hypoxic cells was more evident than on normoxic cells in both cell lines. Further mechanism studies by western blot showed that under normoxia AT-406 decreased the level of cIAP1 in Hela cells in a dose-dependent manner; while additional downregulation of XIAP expression was induced by AT-406 treatment under hypoxia in both cell lines. Finally, AT-406 works on both extrinsic death receptor and intrinsic mitochondrial apoptosis pathways to activate apoptosis. Totally, AT-406 acts as a strong radiosensitizer in human cervical cancer cells, especially in hypoxic condition.

  16. Identification and Characterization of a Small Inhibitory Peptide That Can Target DNA-PKcs Autophosphorylation and Increase Tumor Radiosensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Sun Xiaonan [Department of Radiation Oncology, Sir Run Run Shaw Hospital, Sir Run Run Shaw Institute of Clinical Medicine of Zhejiang University, Hangzhou (China); Yang Chunying [Department of Radiation Oncology, Methodist Hospital Research Institute, Weill Cornell Medical College, Houston, TX (United States); Liu Hai; Wang Qi [Department of Radiation Oncology, Sir Run Run Shaw Hospital, Sir Run Run Shaw Institute of Clinical Medicine of Zhejiang University, Hangzhou (China); Wu Shixiu [Department of Radiation Oncology, The First Affiliated Hospital of Wenzhou Medical College, Wenzhou (China); Li Xia; Xie Tian [Research Center of Biomedicine and Health, Hangzhou Normal University, Hangzhou (China); Brinkman, Kathryn L.; Teh, Bin S.; Butler, E. Brian [Department of Radiation Oncology, Methodist Hospital Research Institute, Weill Cornell Medical College, Houston, TX (United States); Xu Bo, E-mail: bxu@tmhs.org [Department of Radiation Oncology, Methodist Hospital Research Institute, Weill Cornell Medical College, Houston, TX (United States); Zheng, Shu, E-mail: zhengshu@zju.edu.cn [Cancer Institute, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou (China)

    2012-12-01

    Purpose: The DNA protein kinase catalytic subunit (DNA-PKcs) is one of the critical elements involved in the DNA damage repair process. Inhibition of DNA-PKcs results in hypersensitivity to ionizing radiation (IR); therefore, this approach has been explored to develop molecular targeted radiosensitizers. Here, we aimed to develop small inhibitory peptides that could specifically target DNA-PKcs autophosphorylation, a critical step for the enzymatic activation of the kinase in response to IR. Methods and Materials: We generated several small fusion peptides consisting of 2 functional domains, 1 an internalization domain and the other a DNA-PKcs autophosphorylation inhibitory domain. We characterized the internalization, toxicity, and radiosensitization activities of the fusion peptides. Furthermore, we studied the mechanisms of the inhibitory peptides on DNA-PKcs autophosphorylation and DNA repair. Results: We found that among several peptides, the biotin-labeled peptide 3 (BTW3) peptide, which targets DNA-PKcs threonine 2647 autophosphorylation, can abrogate IR-induced DNA-PKcs activation and cause prolonged {gamma}-H2AX focus formation. We demonstrated that BTW3 exposure led to hypersensitivity to IR in DNA-PKcs-proficient cells but not in DNA-PKcs-deficient cells. Conclusions: The small inhibitory peptide BTW3 can specifically target DNA-PKcs autophosphorylation and enhance radiosensitivity; therefore, it can be further developed as a novel class of radiosensitizer.

  17. Identification and Characterization of a Small Inhibitory Peptide That Can Target DNA-PKcs Autophosphorylation and Increase Tumor Radiosensitivity

    International Nuclear Information System (INIS)

    Sun Xiaonan; Yang Chunying; Liu Hai; Wang Qi; Wu Shixiu; Li Xia; Xie Tian; Brinkman, Kathryn L.; Teh, Bin S.; Butler, E. Brian; Xu Bo; Zheng, Shu

    2012-01-01

    Purpose: The DNA protein kinase catalytic subunit (DNA-PKcs) is one of the critical elements involved in the DNA damage repair process. Inhibition of DNA-PKcs results in hypersensitivity to ionizing radiation (IR); therefore, this approach has been explored to develop molecular targeted radiosensitizers. Here, we aimed to develop small inhibitory peptides that could specifically target DNA-PKcs autophosphorylation, a critical step for the enzymatic activation of the kinase in response to IR. Methods and Materials: We generated several small fusion peptides consisting of 2 functional domains, 1 an internalization domain and the other a DNA-PKcs autophosphorylation inhibitory domain. We characterized the internalization, toxicity, and radiosensitization activities of the fusion peptides. Furthermore, we studied the mechanisms of the inhibitory peptides on DNA-PKcs autophosphorylation and DNA repair. Results: We found that among several peptides, the biotin-labeled peptide 3 (BTW3) peptide, which targets DNA-PKcs threonine 2647 autophosphorylation, can abrogate IR-induced DNA-PKcs activation and cause prolonged γ-H2AX focus formation. We demonstrated that BTW3 exposure led to hypersensitivity to IR in DNA-PKcs-proficient cells but not in DNA-PKcs-deficient cells. Conclusions: The small inhibitory peptide BTW3 can specifically target DNA-PKcs autophosphorylation and enhance radiosensitivity; therefore, it can be further developed as a novel class of radiosensitizer.

  18. Differential radiosensitivity among B cell subpopulations

    International Nuclear Information System (INIS)

    Riggs, J.E.

    1988-01-01

    The selective radiosensitivity of sIgM >> sIgD marginal zone B cells is associated with the selective loss of B cell function. The simultaneous restoration of impaired function and recovery of these cells with time supports this premise. B cell recovery, delayed one week after irradiation, is in progress at two weeks, and virtually complete by three weeks. XID mice reveal similar recovery kinetics although there are fewer recovering cells and these bear reduced levels of Ia. This observation represents additional evidence that xid B cells are distinct from those of normal mice. The simultaneous loss, and concurrent recovery, of sIgM >> sIgD B cells and TI-2 responsiveness in irradiated mice suggests the existence of a unique B cell subpopulation possessing both phenotypes. Additional support for this hypothesis is provided by demonstrating that splenocytes, depleted of IgD + cells adoptively reconstitute this response in XID mice. The peritoneal B cell pool, which, compared to the spleen, consist of increased numbers of sIgM >> sIgD B cells, is shown to be a source of radiosensitive B cells that are TI-2 responsive. These observations represent additional evidence for an association between sIgM >> sIgD B cells and TI-2 responsiveness

  19. Evaluation of nitrobenzimidazoles as hypoxic cell radiosensitizers

    International Nuclear Information System (INIS)

    Wright, J.; Frank, L.R.; Bush, D.; Harrison, G.H.

    1983-01-01

    Radiobiological and pharmacokinetic assays were performed to determine the potential of 2-nitrobenzimidazole (NBI) as a hypoxic cell radiosensitizing agent. As judged by comparing survival curve slopes of Serratia marcescens irradiated under aerated and hypoxic conditions, the NBI enhancement ratio (ER) at 2 mM concentration was 2.4 +- 0.2, compared with an oxygen enhancement ratio of 3.3 +- 0.3. 2,5-Dinitrobenzimidazole (DNBI) was investigated in vitro; its ER was 3.0 +- 0.3 at 4 mM concentration. Very poor tissue penetration of DNBI precluded further testing in vivo. Acute toxic signs appeared in C3H/HeJ mice following ip injection of NBI at 100 mg/kg. These would be partly attributable to the stress caused by the high pH of the injection vehicle. The LD 50 was estimated to be 125 to 150 mg/kg. Mammary adenocarcinoma tumors grown in the flanks of these mice exhibited maximum NBI levels at 5 min postinjection (ip). Peak tumor radiosensitization occurred in the interval between 5 and 10 min postinjection. The ER for tumor regrowth delay was 2.1 +- 0.3 following 50 mg/kg injected into mice 5 min before irradiation. Functional evaluation up to 40 days after treatment revealed no evidence of neurological deficit

  20. Evaluation of nitrobenzimidazoles as hypoxic cell radiosensitizers

    International Nuclear Information System (INIS)

    Wright, J.; Frank, L.R.; Bush, D.; Harrison, G.H.

    1983-01-01

    Radiobiological and pharmacokinetic assays were performed to determine the potential of 2-nitrobenzimidazole (NBI) as a hypoxic cell radiosensitizing agent. As judged by comparing survival curve slopes of Serratia marcescens irradiated under aerated and hypoxic conditions, the NBI enhancement ratio (ER) at 2 mM concentration was 2.4 +/- 0.2, compared with an oxygen enhancement ratio of 3.3 +/- 0.3. 2,5-Dinitrobenzimidazole (DNBI) was investigated in vitro; its ER was 3.0 +/- 0.3 at 4 mM concentration. Very poor tissue penetration of DNBI precluded further testing in vivo. Acute toxic signs appeared in C3H/HeJ mice following ip injection of NBI at 100 mg/kg. These would be partly attributable to the stress caused by the high pH of the injection vehicle. The LD50 was estimated to be 125-150 mg/kg. Mammary adenocarcinoma tumors grown in the flanks of these mice exhibited maximum NBI levels at 5 min postinjection (ip). Peak tumor radiosensitization occurred in the interval between 5 and 10 min postinjection. The ER for tumor regrowth delay was 2.1 +/- 0.3 following 50 mg/kg injected into mice 5 min before irradiation. Functional evaluation up to 40 days after treatment revealed no evidence of neurological deficit

  1. Mechanisms of oxygen radiosensitization in CHO cells

    International Nuclear Information System (INIS)

    Whillans, D.W.

    1981-01-01

    A model is presented for repair and fixation pathways when CHO cells are irradiated in the presence of O 2 . This analysis predicts that an increase in the repair path such as has been postulated for addition of a radioprotective sulfhydryl should increase OER/sub max/ in porportion to k prime, the new repair rate constant and also increase K with k prime. Any radiosensitizer which mimics the action of O 2 simply increases k prime 2 , so that the OER/sub max/ decreases at 1/k prime 2 but K increases as k prime 2 . These predictions have been tested in mammalian CHO cells making use of a Clark-type oxygen probe with defined conditions to ensure that O 2 is not depleted by radiation or cellular consumption, and so O 2 levels are known with accuracy. In a complementary study, the technique of rapid-mixing was used to measure the rate of development of O 2 sensitization in these same cells. By a variation of this rapid-mixing approach, the rate of diffusion into these cells has also been measured independently. Neither the dependence of OER on O 2 concentration nor the development of radiosensitivity with time of incubation in O 2 gives evidence in CHO cells for two components of sensitization indicative of two sites or two mechanisms of action, as seen in some V79 sublines. 13 references, 4 figures

  2. Molecular mechanism of radiosensitization by nitro compounds

    International Nuclear Information System (INIS)

    Kagiya, T.; Wada, T.; Nishimoto, S.I.

    1984-01-01

    In this chapter a molecular mechanism of radiosensitization by electron-affinic nitro compounds is discussed, mainly on the basis of the results of the radiation-induced chemical studies of DNA-related compounds in aqueous solutions. In Section II the general aspects of the radiation chemistry of organic compounds in the absence and presence of oxygen in aqueous solution are shown in order to demonstrate characteristic differences between radiation chemical reactions in hypoxic and oxic cells. The effects of nitro compounds on the radiolysis yields of DNA-related compounds in aqueous solutions are described in Section III. In Section IV the retardation effects of misonidazole on the radiation chemical processes of DNA-related compounds are shown along with the reaction characteristics of misonidazole with hydroxyl radical ( . OH) and hydrated electron (e/sub aq/-bar) produced by the radiolysis of water. The promotion of radiation-induced oxidation of thymine into thymine glycol (TG) by nitro radiosensitizers in deoxygenated solution and the relations between the activity of nitro compound for the thymine glycol formation and the enhancement activity measured in vitro are described in Section V. Finally, the protection against radiation-induced damage of thymine by a sulfhydryl compound of glutathione and the ability of electron-affinic compounds to decompose the intracellular radioprotector are described in Section VI

  3. Immunosuppression by hypoxic cell radiosensitizers: a phenomenon of potential clinical importance

    International Nuclear Information System (INIS)

    Rockwell, S.; Kapp, D.S.

    1982-01-01

    The nitroimidazoles metronidazole, misonidazol, and desmethyl misonidazole are currently undergoing clinical trials as possible adjuncts to radiotherapy. Ongoing clinical trials are evaluating the effectiveness of these agents and also documenting the pharmacokinetics and toxicities of radiosensitizing doses of these drugs in man. A variety of toxic effects have been noted in man, including anorexia, nausea and vomiting, peripheral neuropathy, central nervous system symptoms, ototoxicity, allergy, and fear. Laboratory studies have also suggested that these agents have potential to be mutagenic, carcinogenic, and teratogenic. In the editorial presented, the author attempts to draw attention to an additional toxic effect of nitroimidazoles - the inhibition of cell-mediated immune responses

  4. Comparison of the radiosensitivity of three goldfish cell lines using short term endpoints

    Energy Technology Data Exchange (ETDEWEB)

    Mitani, H. (Tokyo Univ. (Japan). Faculty of Science)

    1984-06-01

    The induction and rejoining of DNA strand breaks after ..gamma..-irradiation in three goldfish (Carassius auratus) cell lines with different sensitivities to the lethal effect of ..gamma..-rays has been studied by the DNA strand separation method using hydroxylapatite chromatography. The induction and rejoining of DNA strand breaks was similar in all cell lines. There was also little difference in the degree of inhibition of DNA synthesis immediately after irradiation. However, the rank orders of the durations of division delay and the radiosensitivities of the three cell lines were the same.

  5. Radiosensitizing effect of PSMC5, a 19S proteasome ATPase, in H460 lung cancer cells

    International Nuclear Information System (INIS)

    Yim, Ji-Hye; Yun, Hong Shik; Lee, Su-Jae; Baek, Jeong-Hwa; Lee, Chang-Woo; Song, Ji-Young; Um, Hong-Duck; Park, Jong Kuk; Kim, Jae-Sung; Park, In-Chul; Hwang, Sang-Gu

    2016-01-01

    The function of PSMC5 (proteasome 26S subunit, ATPase 5) in tumors, particularly with respect to cancer radioresistance, is not known. Here, we identified PSMC5 as a novel radiosensitivity biomarker, demonstrating that radiosensitive H460 cells were converted to a radioresistance phenotype by PSMC5 depletion. Exposure of H460 cells to radiation induced a marked accumulation of cell death-promoting reactive oxygen species, but this effect was blocked in radiation-treated H460 PSMC5-knockdown cells through downregulation of the p53-p21 pathway. Interestingly, PSMC5 depletion in H460 cells enhanced both AKT activation and MDM2 transcription, thereby promoting the degradation of p53 and p21 proteins. Furthermore, specific inhibition of AKT with triciribine or knockdown of MDM2 with small interfering RNA largely restored p21 expression in PSMC5-knockdown H460 cells. Our data suggest that PSMC5 facilitates the damaging effects of radiation in radiation-responsive H460 cancer cells and therefore may serve as a prognostic indicator for radiotherapy and molecular targeted therapy in lung cancer patients. - Highlights: • PSMC5 is a radiation-sensitive biomarker in H460 cells. • PSMC5 depletion inhibits radiation-induced apoptosis in H460 cells. • PSMC5 knockdown blocks ROS generation through inhibition of the p53-p21 pathway. • PSMC5 knockdown enhances p21 degradation via AKT-dependent MDM2 stabilization.

  6. The Functional Networks of Prepulse Inhibition: Neuronal Connectivity Analysis Based on FDG-PET in Awake and Unrestrained Rats.

    Directory of Open Access Journals (Sweden)

    Cathrin Rohleder

    2016-07-01

    Full Text Available Prepulse inhibition (PPI is a neuropsychological process during which a weak sensory stimulus (prepulse attenuates the motor response (startle reaction to a subsequent strong startling stimulus. It is measured as a surrogate marker of sensorimotor gating in patients suffering from neuropsychological diseases such as schizophrenia, as well as in corresponding animal models. A variety of studies has shown that PPI of the acoustical startle reaction comprises three brain circuitries for: i startle mediation, ii PPI mediation and iii modulation of PPI mediation. While anatomical connections and information flow in the startle and PPI mediation pathways are well known, spatial and temporal interactions of the numerous regions involved in PPI modulation are incompletely understood.We therefore combined [18F]fluoro-2-deoxyglucose positron-emission-tomography (FDG-PET with PPI and resting state control paradigms in awake rats. A battery of subtractive, correlative as well as seed-based functional connectivity analyses revealed a default mode-like network (DMN active during resting state only. Furthermore, two functional networks were observed during PPI: Metabolic activity in the lateral circuitry was positively correlated with PPI effectiveness and involved the auditory system and emotional regions. The medial network was negatively correlated with PPI effectiveness, i.e. associated with startle, and recruited a spatial/cognitive network. Our study provides evidence for two distinct neuronal networks, whose continuous interplay determines PPI effectiveness in rats, probably by either protecting the prepulse or facilitating startle processing.Discovering similar networks affected in neuropsychological disorders may help to better understand mechanisms of sensorimotor gating deficits and provide new perspectives for therapeutic strategies.

  7. The Functional Networks of Prepulse Inhibition: Neuronal Connectivity Analysis Based on FDG-PET in Awake and Unrestrained Rats.

    Science.gov (United States)

    Rohleder, Cathrin; Wiedermann, Dirk; Neumaier, Bernd; Drzezga, Alexander; Timmermann, Lars; Graf, Rudolf; Leweke, F Markus; Endepols, Heike

    2016-01-01

    Prepulse inhibition (PPI) is a neuropsychological process during which a weak sensory stimulus ("prepulse") attenuates the motor response ("startle reaction") to a subsequent strong startling stimulus. It is measured as a surrogate marker of sensorimotor gating in patients suffering from neuropsychological diseases such as schizophrenia, as well as in corresponding animal models. A variety of studies has shown that PPI of the acoustical startle reaction comprises three brain circuitries for: (i) startle mediation, (ii) PPI mediation, and (iii) modulation of PPI mediation. While anatomical connections and information flow in the startle and PPI mediation pathways are well known, spatial and temporal interactions of the numerous regions involved in PPI modulation are incompletely understood. We therefore combined [(18)F]fluoro-2-deoxyglucose positron-emission-tomography (FDG-PET) with PPI and resting state control paradigms in awake rats. A battery of subtractive, correlative as well as seed-based functional connectivity analyses revealed a default mode-like network (DMN) active during resting state only. Furthermore, two functional networks were observed during PPI: Metabolic activity in the lateral circuitry was positively correlated with PPI effectiveness and involved the auditory system and emotional regions. The medial network was negatively correlated with PPI effectiveness, i.e., associated with startle, and recruited a spatial/cognitive network. Our study provides evidence for two distinct neuronal networks, whose continuous interplay determines PPI effectiveness in rats, probably by either protecting the prepulse or facilitating startle processing. Discovering similar networks affected in neuropsychological disorders may help to better understand mechanisms of sensorimotor gating deficits and provide new perspectives for therapeutic strategies.

  8. Radiation and chemical interactions producing cellular and subcellular damage and their repair. Coordinated programme on improvement in radiotherapy of cancer using modifiers of radiosensitivity of cells

    International Nuclear Information System (INIS)

    Kada, T.

    1982-01-01

    As a result of biochemical studies on the DNA repair of damages induced by ionizing radiation as well as on the radiosensitization with chemicals containing halogen atoms, it was suggested that inhibition of the post-irradiation repair by chemical factors may be useful in improving the radiotherapy. It was possbile to prepare an in vitro repair system in combination with transforming DNA of Bacillus subtilis as well as human placenta extracts; it was shown that certain radiosensitizers worked actually as repair inhibitors in this in vitro system

  9. Survivin, a target to modulate the radiosensitivity of Ewing's sarcoma

    International Nuclear Information System (INIS)

    Greve, B.; Sheikh-Mounessi, F.; Ernst, I.; Eich, H.T.; Kemper, B.; Goette, M.

    2012-01-01

    Background and purpose: Radiotherapy constitutes an essential element in the multimodal therapy of Ewing's sarcoma. Compared to other sarcomas, Ewing tumors normally show a good response to radiotherapy. However, there are consistently tumors with a radioresistant phenotype, and the underlying mechanisms are not known in detail. Here we investigated the association between survivin protein expression and the radiosensitivity of Ewing's sarcoma in vitro. Material and methods: An siRNA-based knockdown approach was used to investigate the influence of survivin expression on cell proliferation, double-strand break (DSB) induction and repair, apoptosis and colony-forming ability in four Ewing's sarcoma cell lines with and without irradiation. Results: Survivin protein and mRNA were upregulated in all cell lines tested in a dose-dependent manner. As a result of survivin knockdown, STA-ET-1 cells showed reduced cell proliferation, an increased number of radiation-induced DSBs, and reduced repair. Apoptosis was increased by knockdown alone and increased further in combination with irradiation. Colony formation was significantly reduced by survivin knockdown in combination with irradiation. Conclusion: Survivin is a radiation-inducible protein in Ewing's sarcoma and its down-regulation sensitizes cells toward irradiation. Survivin knockdown in combination with radiation inhibits cell proliferation, repair, and colony formation significantly and increases apoptosis more than each single treatment alone. This might open new perspectives in the radiation treatment of Ewing's sarcoma. (orig.)

  10. DNA-radiosensitivity and repair in mammolian cells

    International Nuclear Information System (INIS)

    Proskuryakov, S.Ya.; Ivannik, B.P.; Ryabchenko, N.I.

    1979-01-01

    Determination was made of the formation and repair of single-stranded DNA breaks (SB) in cells of rat thymus and liver and Ehrlich's ascites tumor (EAT) with the use of the method of low-gradient viscosimetry of alkaline cell lysates. The radiochemical yield of single-stranded breaks (Gsub(SB)) induced by irradiation of animals is 41.2 eV/break for hepatocytes, 96.8 eV/break, for thymocytes, and 129.7 eV/break, for EAT cells. The half-recovery time of single-stranded DNA breaks for cells of thymus and EAT exposed in vivo is 16.0 and 5.1 s -1 , correspondingly. In hepatocytes exposed in vivo and in vitro no repairs occurs for 3 h. Under conditions of inhibition of SB repair, when suspensions of thymocytes and hepatocytes were exposed in vitro at 4 deg C, Gsub(SB) is 35.5 and 38.7 eV/break, respectively. The analysis of the data obtained prompts the conclusion that under in vivo conditions, there is a correlation between DNA radiosensitivity and the rate of repair processes

  11. Survivin, a target to modulate the radiosensitivity of Ewing's sarcoma.

    Science.gov (United States)

    Greve, B; Sheikh-Mounessi, F; Kemper, B; Ernst, I; Götte, M; Eich, H T

    2012-11-01

    Radiotherapy constitutes an essential element in the multimodal therapy of Ewing's sarcoma. Compared to other sarcomas, Ewing tumors normally show a good response to radiotherapy. However, there are consistently tumors with a radioresistant phenotype, and the underlying mechanisms are not known in detail. Here we investigated the association between survivin protein expression and the radiosensitivity of Ewing's sarcoma in vitro. An siRNA-based knockdown approach was used to investigate the influence of survivin expression on cell proliferation, double-strand break (DSB) induction and repair, apoptosis and colony-forming ability in four Ewing's sarcoma cell lines with and without irradiation. Survivin protein and mRNA were upregulated in all cell lines tested in a dose-dependent manner. As a result of survivin knockdown, STA-ET-1 cells showed reduced cell proliferation, an increased number of radiation-induced DSBs, and reduced repair. Apoptosis was increased by knockdown alone and increased further in combination with irradiation. Colony formation was significantly reduced by survivin knockdown in combination with irradiation. Survivin is a radiation-inducible protein in Ewing's sarcoma and its down-regulation sensitizes cells toward irradiation. Survivin knockdown in combination with radiation inhibits cell proliferation, repair, and colony formation significantly and increases apoptosis more than each single treatment alone. This might open new perspectives in the radiation treatment of Ewing's sarcoma.

  12. The development of genes associated with radiosensitivity of cervical cancer

    International Nuclear Information System (INIS)

    Li Hongyan; Chen Zhihua; He Guifang

    2007-01-01

    It has a good application prospect to predict effects of radiotherapy by examining radiosensitivity of patients with cervical cancers before their radiotherapy. Prediction of tumor cell radiosensitivity according to their level of gene expression and gene therapy to reverse radio-resistance prior to radiation on cervical cancers are heated researches on tumor therapy. The expression of some proliferation-related genes, apoptosis-related genes and hypoxia-related genes can inerease the radiosensitivity of cervical cancer. Microarray technology may have more direct applications to the study of biological pathway contributing to radiation resistance and may lead to development of alternative treatment modalities. (authors)

  13. The Effect of VPA on Increasing Radiosensitivity in Osteosarcoma Cells and Primary-Culture Cells from Chemical Carcinogen-Induced Breast Cancer in Rats.

    Science.gov (United States)

    Liu, Guochao; Wang, Hui; Zhang, Fengmei; Tian, Youjia; Tian, Zhujun; Cai, Zuchao; Lim, David; Feng, Zhihui

    2017-05-10

    This study explored whether valproic acid (VPA, a histone deacetylase inhibitor) could radiosensitize osteosarcoma and primary-culture tumor cells, and determined the mechanism of VPA-induced radiosensitization. The working system included osteosarcoma cells (U2OS) and primary-culture cells from chemical carcinogen (DMBA)-induced breast cancer in rats; and clonogenic survival, immunofluorescence, fluorescent in situ hybridization (FISH) for chromosome aberrations, and comet assays were used in this study. It was found that VPA at the safe or critical safe concentration of 0.5 or 1.0 mM VPA could result in the accumulation of more ionizing radiation (IR)-induced DNA double strand breaks, and increase the cell radiosensitivity. VPA-induced radiosensitivity was associated with the inhibition of DNA repair activity in the working systems. In addition, the chromosome aberrations including chromosome breaks, chromatid breaks, and radial structures significantly increased after the combination treatment of VPA and IR. Importantly, the results obtained by primary-culture cells from the tissue of chemical carcinogen-induced breast cancer in rats further confirmed our findings. The data in this study demonstrated that VPA at a safe dose was a radiosensitizer for osteosarcoma and primary-culture tumor cells through suppressing DNA-double strand breaks repair function.

  14. Enterolactone: A novel radiosensitizer for human breast cancer cell lines through impaired DNA repair and increased apoptosis

    International Nuclear Information System (INIS)

    Bigdeli, Bahareh; Goliaei, Bahram; Masoudi-Khoram, Nastaran; Jooyan, Najmeh; Nikoofar, Alireza; Rouhani, Maryam; Haghparast, Abbas; Mamashli, Fatemeh

    2016-01-01

    Introduction: Radiotherapy is a potent treatment against breast cancer, which is the most commonly diagnosed cancer among women. However, the emergence of radioresistance due to increased DNA repair leads to radiotherapeutic failure. Applying polyphenols combined with radiation is a more promising method leading to better survival. Enterolactone, a phytoestrogenic polyphenol, has been reported to inhibit an important radioresistance signaling pathway, therefore we conjectured that enterolactone could enhance radiosensitivity in breast cancer. To assess this hypothesis, radiation response of enterolactone treated MDA-MB-231 and T47D cell lines and corresponding cellular mechanisms were investigated. Methods: Cytotoxicity of enterolactone was measured via MTT assay. Cells were treated with enterolactone before X-irradiation, and clonogenic assay was used to evaluate radiosensitivity. Cell cycle distribution and apoptosis were measured by flow cytometric analysis. In addition, DNA damages and corresponding repair, chromosomal damages, and aberrations were assessed by comet, micronucleus, and cytogenetic assays, respectively. Results: Enterolactone decreased the viability of cells in a concentration- and time dependent manner. Enterolactone significantly enhanced radiosensitivity of cells by abrogating G2/M arrest, impairing DNA repair, and increasing radiation-induced apoptosis. Furthermore, increased chromosomal damages and aberrations were detected in cells treated with enterolactone combined with X-rays than X-ray alone. These effects were more prominent in T47D than MDA-MB-231 cells. Discussion: To our knowledge, this is the first report that enterolactone is a novel radiosensitizer for breast cancer irrespective of estrogen receptor status. Authors propose enterolactone as a candidate for combined therapy to decrease the radiation dose delivered to patients and subsequent side effects. - Highlights: • Enterolactone is proposed to be a novel radiosensitizer for

  15. Enterolactone: A novel radiosensitizer for human breast cancer cell lines through impaired DNA repair and increased apoptosis

    Energy Technology Data Exchange (ETDEWEB)

    Bigdeli, Bahareh, E-mail: bhr.bigdeli@ut.ac.ir [Department of Biophysics, Institute of Biochemistry and Biophysics, University of Tehran, 16th Azar St., Enghelab Sq., Tehran (Iran, Islamic Republic of); Goliaei, Bahram, E-mail: goliaei@ut.ac.ir [Department of Biophysics, Institute of Biochemistry and Biophysics, University of Tehran, 16th Azar St., Enghelab Sq., Tehran (Iran, Islamic Republic of); Masoudi-Khoram, Nastaran, E-mail: n.masoudi@alumni.ut.ac.ir [Department of Biophysics, Institute of Biochemistry and Biophysics, University of Tehran, 16th Azar St., Enghelab Sq., Tehran (Iran, Islamic Republic of); Jooyan, Najmeh, E-mail: n.jooyan@ut.ac.ir [Department of Biophysics, Institute of Biochemistry and Biophysics, University of Tehran, 16th Azar St., Enghelab Sq., Tehran (Iran, Islamic Republic of); Nikoofar, Alireza, E-mail: nikoofar@iums.ac.ir [Department of Radiotherapy, Iran University of Medical Sciences (IUMS), Shahid Hemmat Highway, Tehran (Iran, Islamic Republic of); Rouhani, Maryam, E-mail: rouhani@iasbs.ac.ir [Department of Biological Sciences, Institute for Advanced Studies in Basic Sciences (IASBS), Prof. Yousef Sobouti Blvd., Gava Zang, Zanjan (Iran, Islamic Republic of); Haghparast, Abbas, E-mail: Haghparast@sbmu.ac.ir [Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Daneshjo St., Evin, Tehran (Iran, Islamic Republic of); Mamashli, Fatemeh, E-mail: mamashli@ut.ac.ir [Department of Biophysics, Institute of Biochemistry and Biophysics, University of Tehran, 16th Azar St., Enghelab Sq., Tehran (Iran, Islamic Republic of)

    2016-12-15

    Introduction: Radiotherapy is a potent treatment against breast cancer, which is the most commonly diagnosed cancer among women. However, the emergence of radioresistance due to increased DNA repair leads to radiotherapeutic failure. Applying polyphenols combined with radiation is a more promising method leading to better survival. Enterolactone, a phytoestrogenic polyphenol, has been reported to inhibit an important radioresistance signaling pathway, therefore we conjectured that enterolactone could enhance radiosensitivity in breast cancer. To assess this hypothesis, radiation response of enterolactone treated MDA-MB-231 and T47D cell lines and corresponding cellular mechanisms were investigated. Methods: Cytotoxicity of enterolactone was measured via MTT assay. Cells were treated with enterolactone before X-irradiation, and clonogenic assay was used to evaluate radiosensitivity. Cell cycle distribution and apoptosis were measured by flow cytometric analysis. In addition, DNA damages and corresponding repair, chromosomal damages, and aberrations were assessed by comet, micronucleus, and cytogenetic assays, respectively. Results: Enterolactone decreased the viability of cells in a concentration- and time dependent manner. Enterolactone significantly enhanced radiosensitivity of cells by abrogating G2/M arrest, impairing DNA repair, and increasing radiation-induced apoptosis. Furthermore, increased chromosomal damages and aberrations were detected in cells treated with enterolactone combined with X-rays than X-ray alone. These effects were more prominent in T47D than MDA-MB-231 cells. Discussion: To our knowledge, this is the first report that enterolactone is a novel radiosensitizer for breast cancer irrespective of estrogen receptor status. Authors propose enterolactone as a candidate for combined therapy to decrease the radiation dose delivered to patients and subsequent side effects. - Highlights: • Enterolactone is proposed to be a novel radiosensitizer for

  16. The HSP90 inhibitor NVP-AUY922 radiosensitizes by abrogation of homologous recombination resulting in mitotic entry with unresolved DNA damage.

    Directory of Open Access Journals (Sweden)

    Shane Zaidi

    Full Text Available Heat shock protein 90 (HSP90 is a molecular chaperone responsible for the conformational maintenance of a number of client proteins that play key roles in cell cycle arrest, DNA damage repair and apoptosis following radiation. HSP90 inhibitors exhibit antitumor activity by modulating the stabilisation and activation of HSP90 client proteins. We sought to evaluate NVP-AUY922, the most potent HSP90 inhibitor yet reported, in preclinical radiosensitization studies.NVP-AUY922 potently radiosensitized cells in vitro at low nanomolar concentrations with a concurrent depletion of radioresistance-linked client proteins. Radiosensitization by NVP-AUY922 was verified for the first time in vivo in a human head and neck squamous cell carcinoma xenograft model in athymic mice, as measured by delayed tumor growth and increased surrogate end-point survival (p = <0.0001. NVP-AUY922 was shown to ubiquitously inhibit resolution of dsDNA damage repair correlating to delayed Rad51 foci formation in all cell lines tested. Additionally, NVP-AUY922 induced a stalled mitotic phenotype, in a cell line-dependent manner, in HeLa and HN5 cell lines irrespective of radiation exposure. Cell cycle analysis indicated that NVP-AUY922 induced aberrant mitotic entry in all cell lines tested in the presence of radiation-induced DNA damage due to ubiquitous CHK1 depletion, but resultant downstream cell cycle effects were cell line dependent.These results identify NVP-AUY922 as the most potent HSP90-mediated radiosensitizer yet reported in vitro, and for the first time validate it in a clinically relevant in vivo model. Mechanistic analysis at clinically achievable concentrations demonstrated that radiosensitization is mediated by the combinatorial inhibition of cell growth and survival pathways, ubiquitous delay in Rad51-mediated homologous recombination and CHK1-mediated G(2/M arrest, but that the contribution of cell cycle perturbation to radiosensitization may be cell line

  17. Radiosensitivity and chimera formation in Hibiscus syriacus

    International Nuclear Information System (INIS)

    Kwon, S.H.; Won, J.L.

    1980-01-01

    Radiosensitivity of gamma-irradiated Hibiscus syriacus and chimera formation were investigated. The lethal dose-50 percent with respect to seeding and cuttings was 15kR and 2 approximately 3 kR respectively, chlorophyll mutation rate of seeds irradiated with 15 kR being about 13 percent. The degree of chimeric leaf mutants from the buds by radiation treatment depends on the bud position of the branch. Buds of the middle part of V 1 branch seemed to be more multi-cellular condition than the upper and low part when irradiation was made. It is assumed that at least two primordia of V 2 branch were already differentiated from the V 1 branch in Hibiscus syriacus plant. (Author)

  18. Clinical experience with the radiosensitizer misonidazole

    International Nuclear Information System (INIS)

    Kogelnik, D.; Szepesi, T.; Kaercher, K.H.; Seitz, W.

    1979-01-01

    From April 1976 to June 1978, 74 cancer patients were treated with multiple doses of misonidazole at the University Clinic for Radiotherapy and Radiobiology of Vienna. Thirtyone patients had inoperable brain tumors or high-grade astrocytomas, the remaining patients suffered from late stages of various extracerebral malignancies. All patients were hospitalized and thoroughly examined for possible side-effects of this currently most promising hypoxic cell radiosensitizer. Neurotoxicity, principally the development of peripheral neuropathies, is the most important limiting factor in the clinical application of misonidazole. With total doses of 12 g/m 2 of surface area a low and acceptable incidence of neuropathies is seen. By extension of the over-all treatment time to 6-8 weeks the total dose may be increased to 15 g/m 2 . (orig.) 891 MG/orig. 892 RDG [de

  19. Radiosensitivity of cultured insect cells: II. Diptera

    International Nuclear Information System (INIS)

    Koval, T.M.

    1983-01-01

    The radiosensitivity of five dipteran cell lines representing three mosquito genera and one fruit fly genus were examined. These lines are: (1) ATC-10, Aedes aegypti; (2) RU-TAE-14, Toxorhynchites amboinensis; (3) RU-ASE-2A, Anopheles stephensi; (4) WR69-DM-1, Drosophila melanogaster; and (5) WR69-DM-2, Drosophila melanogaster. Population doubling times for these lines range from approximately 16 to 48 hr. Diploid chromosome numbers are six for the mosquito cells and eight for the fruit fly cells D 0 values are 5.1 and 6.5 Gy for the Drosophila cell lines and 3.6, 6.2, and 10.2 Gy for the mosquito cell lines. The results of this study demonstrate that dipteran insect cells are a few times more resistant to radiation than mammalian cells, but not nearly as radioresistant as lepidopteran cells

  20. RNA binding protein RNPC1 inhibits breast cancer cells metastasis via activating STARD13-correlated ceRNA network.

    Science.gov (United States)

    Zhang, Zhiting; Guo, Qianqian; Zhang, Shufang; Xiang, Chenxi; Guo, Xinwei; Zhang, Feng; Gao, Lanlan; Ni, Haiwei; Xi, Tao; Zheng, Lufeng

    2018-05-07

    RNA binding proteins (RBPs) are pivotal post-transcriptional regulators. RNPC1, an RBP, acts as a tumor suppressor through binding and regulating the expression of target genes in cancer cells. This study disclosed that RNPC1 expression was positively correlated with breast cancer patients' relapse free and overall survival, and RNPC1suppressed breast cancer cells metastasis. Mechanistically, RNPC1 promoting a competing endogenous network (ceRNA) crosstalk between STARD13, CDH5, HOXD10, and HOXD1 (STARD13-correlated ceRNA network) that we previously confirmed in breast cancer cells through stabilizing the transcripts and thus facilitating the expression of these four genes in breast cancer cells. Furthermore, RNPC1 overexpression restrained the promotion of STARD13, CDH5, HOXD10, and HOXD1 knockdown on cell metastasis. Notably, RNPC1 expression was positively correlated with CDH5, HOXD1 and HOXD10 expression in breast cancer tissues, and attenuated adriamycin resistance. Taken together, these results identified that RNPC1 could inhibit breast cancer cells metastasis via promoting STARD13-correlated ceRNA network.

  1. Chromosomal radiosensitivity of lymphocytes in South African breast ...

    African Journals Online (AJOL)

    radiosensitivity has been used as an indirect measure of cancer susceptibility. ... studies have shown that breast cancer patients are more sensitive to ionising radiation than healthy individuals. .... There was an effect of ER positivity on the MN.

  2. HLA‐G modulates the radiosensitivity of human neoplastic cells

    International Nuclear Information System (INIS)

    Michelin, Severino; Gallegos, Cristina; Baffa Trasci, Sofía; Dubner, Diana; Favier, B.; Carosella, E.D.

    2011-01-01

    Tumor cells show a very broad range of radiosensitivities. The differential radiosensitivity may depend on many factors, being the efficiency to recognize and/or repair the DNA lesion, and the cell cycle control mechanisms, the most important (Jeggo and Lavin, 2009; Kumala et al., 2003). Human leukocyte antigen‐G (HLA‐G) is a non‐classical HLA class I molecule involved in fetus protection form the maternal immune system, transplant tolerance, and viral and tumoral immune escape (Carosella et al., 2008). It has been determined that gamma radiation modulates HLA‐G expression at the plasma membrane of human melanoma cells. However, its role in tumoral radiosensitivity has not been demonstrated yet. The objective of this work was to determine if the radiosensitivity of human neoplastic cell lines cultured in vitro was mediated by HLA‐G expression. (authors)

  3. Radiosensitization of mouse skin by oxygen and depletion of glutathione

    International Nuclear Information System (INIS)

    Stevens, Graham; Joiner, Michael; Joiner, Barbara; Johns, Helen; Denekamp, Juliana

    1995-01-01

    Purpose: To determine the oxygen enhancement ratio (OER) and shape of the oxygen sensitization curve of mouse foot skin, the extent to which glutathione (GSH) depletion radiosensitized skin, and the dependence of such sensitization on the ambient oxygen tension. Methods and Materials: The feet of WHT mice were irradiated with single doses of 240 kVp x-rays while mice were exposed to carbogen or gases with oxygen/nitrogen mixtures containing 8-100% O 2 . The anoxic response was obtained by occluding the blood supply to the leg of anesthetized mice with a tourniquet, surrounding the foot with nitrogen, and allowing the mice to breathe 10% O 2 . Further experiments were performed to assess the efficacy of this method to obtain an anoxic response. Radiosensitivity of skin was assessed using the acute skin-reaction assay. Glutathione levels were modified using two schedules of dl-buthionine sulphoximine (BSO) and diethylmaleate (DEM), which were considered to produce extensive and intermediate levels of GSH depletion in the skin of the foot during irradiation. Results: Carbogen caused the greatest radiosensitization of skin, with a reproducible enhancement of 2.2 relative to the anoxic response. The OER of 2.2 is lower than other reports for mouse skin. This may indicate that the extremes of oxygenation were not produced, although there was no direct evidence for this. When skin radiosensitivity was plotted against the logarithm of the oxygen tension in the ambient gas, a sigmoid curve with a K value of 17-21% O 2 in the ambient gas was obtained. Depletion of GSH caused minimal radiosensitization when skin was irradiated under anoxic or well-oxygenated conditions. Radiosensitization by GSH depletion was maximal at intermediate oxygen tensions of 10-21% O 2 in the ambient gas. Increasing the extent of GSH depletion led to increasing radiosensitization, with sensitization enhancement ratios of 1.2 and 1.1, respectively, for extensive and intermediate levels of GSH

  4. Study on ionizing radiosensitivity of respiratory deficiency yeast mutants

    International Nuclear Information System (INIS)

    Mao Shuhong; Chinese Academy of Sciences, Beijing; Jin Genming; Wei Zengquan; Xie Hongmei

    2006-01-01

    The radiosensitivity of respiratory deficiency yeast mutants has been studied in this work. The mutants which were screened from the yeasts after ionizing irradiation were irradiated with 12 C 6+ at different doses. Because of the great change in its mitochondria and mitochondrial DNA, the respiratory deficiency yeast mutants show radio-sensitivity at dose less than 1 Gy and radioresistance at doses higher than 1 Gy. (authors)

  5. Increasing the radiosensitivity of tumours in an hypoxic environment using inhibitors of the pentose phosphate pathway

    International Nuclear Information System (INIS)

    Sahasrabudhe, M.B.; Bhonsle, S.R.; Krishnamurti, K.; Tilak, B.D.

    1977-01-01

    Rapidly growing tumours contain few blood vessels in the tumour mass. Cells in such tumours obtain nutrients and oxygen from the periphery by diffusion, resulting in a diminishing oxygen and nutrient gradient from the periphery to centre of the tumour mass. In normal tissues, oxygen is utilized via a tricarboxylic acid (TCA) cycle; in tumour cells oxygen is utilized via a hexose monophosphate (HMP) pathway and through the TCA cycle at a 30% reduced level. Interference with the HMP pathway selectively inhibits the utilization of oxygen by tumour cells, thus increasing the availability of oxygen to hypoxic cells situated deeper in the tumour mass. This effect has been exploited for increasing the radiosensitivity of tumour cells situated in an hypoxic environment. The influence of sixteen potential antimetabolites on the HMP pathway has been studied. Of these, six compounds, namely, (1) 2-carboxy 5-hydroxymethyl thiophene, (2) the sodium salt of 2:5 dicarbethoxy 3:4 dihydroxy thiophene, (3) the dihydrazide of 2:5 dicarboxy thiophene, (4) the dihydrazide of 3:4 dimethoxy 2:5 dicarboxy thiophene, (5) trithiocyanuric acid, and (6) cyanuric trithioglycollic acid showed an inhibiting effect on the HMP pathway without any influence on the TCA cycle. Influence of administration of compounds (1), (2) and (4) prior to radiation on the growth of transplanted fibrosarcomas in mice has been studied and is reported here. These three compounds showed marked potentiation of radiosensitivity of tumours. (author)

  6. Anti-EGFR therapy radiosensitizes human lung adenocarcinoma xenograft in nude mouse

    International Nuclear Information System (INIS)

    Wang Hui; Li Tianran; Tian Jiahe; Qu Baolin; Zhu Hui

    2008-01-01

    Objective: To investigate the effect of Gefitinib on radiosensitivity of human lung adenocarcinoma xenograft in nude mouse. Methods: Human lung adenocarcinoma cell line A549 was used to establish nude mouse xenograft tumor model. The mice were derided into 4 groups: control, irradiation alone, Gefinitib alone and radiation combined with Genifitib. Radiation schedule was 3 fractions of 5 Gy, once daily. Gefitinib was daily administered by gavage at 100 mg/(kg·day -1 ) for 14 days. In the combination group, radiotherapy was performed 2 hours after Gefitinib administration. Tumor diameter was measured every other day. Percentage of tumor growth inhibition, growth delay time and regrowth delay time were evaluated. Results: For A549 xenografts in radiation alone, gefitinib alone and combination therapy groups, the percentage of tumor growth inhibition was 22.7%, 12.4% and 38.2%, respectively (F=25.75, P=0.000). Tumor growth delay time was 6.0, 7.8 and 21.6 days, respectively (F=70.49, P=0.000). Tumor regrowth delay time in combination therapy and irradiation alone groups was 23.4 and 10.2 days. (F=174.24, P= 0.000). Sensitizing enhancement ratio of combination group was 1.5 in growth and 1.7 in regrowth. Conclusions: Anti-EGFR therapy enhances the radiosensitivity of human lung adenocarcinoma xenograft in nude mouse. (authors)

  7. Effect of sanguinarine on the growth and radiosensitivity of human ovarian cancer cells

    International Nuclear Information System (INIS)

    Xu Jiaying; Ji Junmin; Jiao Yang; Wu Li; Fan Sanjun

    2012-01-01

    Objective: To study the effect of sanguinarine on the growth and radiosensitivity of ovarian cancer SK-OV-3 cells. Methods: Cell growth was determined by MTT and clonogenic assay. Cell cycle analysis was performed by flow cytometry assay. The cell apoptosis was analyzed by Annexin V/PI assay. Results: Sanguinarine inhibited SK-OV-3 cell growth in a dose-and time-dependent fashion and its IC 50 values were 3.02 and 1.11 μmol/L at 24 and 48 h, respectively. Sanguinarine also significantly triggered a sub-G 1 peak, an indicator of apoptosis,and caused a G 0 /G 1 arrest. Furthermore, the cell apoptosis induced by X-irradiation was significantly increased at 6 Gy when the cells were pre-treated with sanguinarine, in which the early apoptotic population increased from 10.28% to 43.28% (t=19.41, P<0.01) and the late apoptotic population increased from 20.26% to 30.80% (t=8.78, P<0.01). The multi-target click model was used to fit survival curves and the SER of sanguinarine treatment approached to 1.625 at the dose of D 0 . Conclusions: Sanguinarine could inhibit SK-OV-3 cell growth by inducing apoptosis and cell cycle arrest and enhance cell radiosensitivity at low doses. (authors)

  8. Hyperthermia radiosensitization in human glioma cells comparison of recovery of polymerase activity, survival, and potentially lethal damage repair

    International Nuclear Information System (INIS)

    Raaphorst, G.P.; Feeley, M.M.

    1994-01-01

    DNA polymerase inactivation is compared to thermal radiosensitization and inhibition of damage recovery in human glioma cells. Two human glioma cell lines (U87MG and U373MG) were exposed to hyperthermia and irradiation. Hyperthermia was given at 43 degrees C and 45 degrees C and DNA polymerase α + δ + ε and β activities were measured. Hyperthermia was given at various times before irradiation and the degree of radiosensitization and polymerase activity was assessed at various times after heating. In addition the ability of cells to undergo repair of potentially lethal radiation damage was assessed for cells irradiated at various times after heating. Polymerase α + δ + ε and polymerase β both recovered after heating but polymerase β was faster and was complete in U373MG but not in the U87MG cell lines after 48 h incubation after heating (45 degrees C, 60 min). Incubation, between hyperthermia and irradiation resulted in a loss of radiosensitization and a loss of inhibition of repair of potentially lethal damage. These changes correlated well with recovery of polymerase β but not with polymerase α + δ + ε. The correlation of polymerase β activity and thermoradiosensitization and its recovery indicate that polymerase β may be one of the mechanisms involved in thermoradiosensitization. 35 refs., 7 figs

  9. Cellular radiosensitivity in human severe-combined-immunodeficiency (SCID) syndromes

    International Nuclear Information System (INIS)

    Sproston, Anthony R.M.; West, Catharine M.L.; Hendry, Jolyon H.

    1997-01-01

    Purpose: The aim of the work was to establish to what extent a variety of human severe-combined-immunodeficiency (SCID) disorders are associated with in vitro cellular hypersensitivity to ionizing radiation. Materials and methods: A study was made of fibroblast strains established from individuals with adenosine deaminase deficiency, T(-)B(-) SCID, Omenn's syndrome and a SCID heterozygote. For comparison, an assessment was also made of the radiosensitivity of a series of fibroblast strains derived from: normal donors, a patient with ataxia-telangiectasia (A-T) and an A-T heterozygote. Radiosensitivity was determined using a clonogenic assay following both high (HDR) and low (LDR) dose-rate irradiation. Results: Following HDR irradiation, the fibroblast strains derived from the different human SCID disorders displayed a wide range of radiosensitivity: the adenosine deaminase deficiency cells were similar in radiosensitivity to normal fibroblasts, T(-)B(-) cells were as hypersensitive to radiation as A-T cells and the Omenn's syndrome cells showed intermediate radiosensitivity. However, whereas all four normal cell strains studied showed significant LDR sparing, none of the SCID fibroblasts did. Conclusions: These data indicate that human SCID is variable in terms of radiosensitivity depending on the particular defect. In addition, the lack of LDR sparing of radiation-induced damage suggests the involvement of some form(s) of DNA repair defect in all the human SCID syndromes

  10. Functional networks of motor inhibition in conversion disorder patients and feigning subjects

    Directory of Open Access Journals (Sweden)

    Thomas Hassa

    2016-01-01

    Full Text Available The neural correlates of motor inhibition leading to paresis in conversion disorder are not well known. The key question is whether they are different of those of normal subjects feigning the symptoms. Thirteen conversion disorder patients with hemiparesis and twelve healthy controls were investigated using functional magnetic resonance tomography under conditions of passive motor stimulation of the paretic/feigned paretic and the non-paretic hand. Healthy controls were also investigated in a non-feigning condition. During passive movement of the affected right hand conversion disorder patients exhibited activations in the bilateral triangular part of the inferior frontal gyri (IFG, with a left side dominance compared to controls in non-feigning condition. Feigning controls revealed for the same condition a weak unilateral activation in the right triangular part of IFG and an activity decrease in frontal midline areas, which couldn't be observed in patients. The results suggest that motor inhibition in conversion disorder patients is mediated by the IFG that was also involved in inhibition processes in normal subjects. The activity pattern in feigning controls resembled that of conversion disorder patients but with a clear difference in the medial prefrontal cortex. Healthy controls showed decreased activity in this region during feigning compared to non-feigning conditions suggesting a reduced sense of self-agency during feigning. Remarkably, no activity differences could be observed in medial prefrontal cortex for patients vs healthy controls in feigning or non-feigning conditions suggesting self-agency related activity in patients to be in between those of non-feigning and feigning healthy subjects.

  11. Functional networks of motor inhibition in conversion disorder patients and feigning subjects.

    Science.gov (United States)

    Hassa, Thomas; de Jel, Esther; Tuescher, Oliver; Schmidt, Roger; Schoenfeld, Mircea Ariel

    2016-01-01

    The neural correlates of motor inhibition leading to paresis in conversion disorder are not well known. The key question is whether they are different of those of normal subjects feigning the symptoms. Thirteen conversion disorder patients with hemiparesis and twelve healthy controls were investigated using functional magnetic resonance tomography under conditions of passive motor stimulation of the paretic/feigned paretic and the non-paretic hand. Healthy controls were also investigated in a non-feigning condition. During passive movement of the affected right hand conversion disorder patients exhibited activations in the bilateral triangular part of the inferior frontal gyri (IFG), with a left side dominance compared to controls in non-feigning condition. Feigning controls revealed for the same condition a weak unilateral activation in the right triangular part of IFG and an activity decrease in frontal midline areas, which couldn't be observed in patients. The results suggest that motor inhibition in conversion disorder patients is mediated by the IFG that was also involved in inhibition processes in normal subjects. The activity pattern in feigning controls resembled that of conversion disorder patients but with a clear difference in the medial prefrontal cortex. Healthy controls showed decreased activity in this region during feigning compared to non-feigning conditions suggesting a reduced sense of self-agency during feigning. Remarkably, no activity differences could be observed in medial prefrontal cortex for patients vs healthy controls in feigning or non-feigning conditions suggesting self-agency related activity in patients to be in between those of non-feigning and feigning healthy subjects.

  12. Effects of age and gender on neural networks of motor response inhibition: from adolescence to mid-adulthood.

    Science.gov (United States)

    Rubia, Katya; Lim, Lena; Ecker, Christine; Halari, Rozmin; Giampietro, Vincent; Simmons, Andrew; Brammer, Michael; Smith, Anna

    2013-12-01

    Functional inhibitory neural networks mature progressively with age. However, nothing is known about the impact of gender on their development. This study employed functional magnetic resonance imaging (fMRI) to investigate the effects of age, sex, and sex by age interactions on the brain activation of 63 healthy males and females, between 13 and 38 years, performing a Stop task. Increasing age was associated with progressively increased activation in typical response inhibition areas of right inferior and dorsolateral prefrontal and temporo-parietal regions. Females showed significantly enhanced activation in left inferior and superior frontal and striatal regions relative to males, while males showed increased activation relative to females in right inferior and superior parietal areas. Importantly, left frontal and striatal areas that showed increased activation in females, also showed significantly increased functional maturation in females relative to males, while the right inferior parietal activation that was increased in males showed significantly increased functional maturation relative to females. The findings demonstrate for the first time that sex-dimorphic activation patterns of enhanced left fronto-striatal activation in females and enhanced right parietal activation in males during motor inhibition appear to be the result of underlying gender differences in the functional maturation of these brain regions. © 2013. Published by Elsevier Inc. All rights reserved.

  13. Modification of radiation effects on E. coli B/r and a radiosensitive mutant Bsub(s-1) by membrane-binding drugs

    International Nuclear Information System (INIS)

    Yonei, S.

    1979-01-01

    In this study, the effects of chlorpromazine, procaine and quinidine on the X-radiation effects on Escherichia coli B/r and its radiosensitive mutant Bsub(s-1) (which is genetically unable to repair radiation damage to DNA) were examined. At chlorpromazine concentrations > = 25 mM, there was loss of colony-forming ability in both strains. Chlorpromazine (0.1 mM) markedly sensitized E. coli B/r under hypoxic conditions of irradiation but not under oxic conditions. There was no significant radiosensitization by chlorpromazine (0.1-1.0mM) in E. coli Bsub(s-1) under either oxic or hypoxic conditions. Similar results were obtained when procaine and quinidine were used as 'membrane-binding radiosensitizers'. Thus these results suggested that radiosensitization by such drugs in E. coli B/r was the result of inhibition of post-irradiation DNA repair in cells. It was concluded that the inhibition of DNA repair could be a secondary consequence of cell membrane alterations or damage caused by the membrane-binding of these drugs. (UK)

  14. Inhibition of Information Flow to the Default Mode Network During Self-Reference Versus Reference to Others.

    Science.gov (United States)

    Soch, Joram; Deserno, Lorenz; Assmann, Anne; Barman, Adriana; Walter, Henrik; Richardson-Klavehn, Alan; Schott, Björn H

    2017-08-01

    The default mode network (DMN), a network centered around the cortical midline, shows deactivation during most cognitive tasks and pronounced resting-state connectivity, but is actively engaged in self-reference and social cognition. It is, however, yet unclear how information reaches the DMN during social cognitive processing. Here, we addressed this question using dynamic causal modeling (DCM) of functional magnetic resonance imaging (fMRI) data acquired during self-reference (SR) and reference to others (OR). Both conditions engaged the left inferior frontal gyrus (LIFG), most likely reflecting semantic processing. Within the DMN, self-reference preferentially elicited rostral anterior cingulate and ventromedial prefrontal cortex (rACC/vmPFC) activity, whereas OR engaged posterior cingulate and precuneus (PCC/PreCun). DCM revealed that the regulation of information flow to the DMN was primarily inhibitory. Most prominently, SR elicited inhibited information flow from the LIFG to the PCC/PreCun, while OR was associated with suppression of the connectivity from the LIFG to the rACC/vmPFC. These results suggest that task-related DMN activation is enabled by inhibitory down-regulation of task-irrelevant information flow when switching from rest to stimulus-specific processing. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  15. Effect of thorium, cerium and lanthanium metals on the radiosensitivity of human osteoblasts

    International Nuclear Information System (INIS)

    Iwahara, Lucas Kiyoshi da Fonseca

    2016-01-01

    This work analyzed the effects of Th, Ce and La combinations on the human osteoblast proliferation. Due to the osteotropic potential of actinides and lanthanides, a human osteoblast cell line was used to evaluate the effects of metals on cell radiosensitivity using cell proliferation and total proteins as indicators. Assays were performed using cultures exposed to metal alone and in combination and to ionising radiation. It was not observed effects on proliferation for cultures exposed to the metals alone. Concerning the influence of the three elements on the radiosensitivity, it was seen that all three metals were able to interfere on this indicator, in a concentration dependent manner. Evaluating cultures exposed to binary mixtures (Th-Ce and Th-La) and a ternary mixture (Th-Ce-La), it was verified that there were chemical interactions between the metals, for the combinations tested. The results showed very strong antagonism on the inhibition of cell proliferation in cultures exposed to Th-La and Th- Ce-La combinations. Regarding the osteoblasts exposed to mixtures and to radiation it was seen an antagonistic effect on the cell proliferation in all tested combinations, and the Th-Ce combination with a higher degree. These results show that metal mixtures containing thorium, in association with ionising radiation, induced different effects on cell proliferation, regarding the exposure to the metals alone, suggesting the possibility that the combinations interfere on osteoblast radiosensitivity expressing the increase of the occupational hazard among workers involved with monazite sands. The results also indicate that the analysis of the effects of metal mixtures on human cells is a more realistic risk assessment in comparison with the analysis of risk for single elements. The work displays the need to development of risk assessment models that include the study of mixtures obtained in the work environment for the evaluation of cytotoxic and radiotoxic effects in

  16. Paraquat-induced radiosensitization of mammalian cells

    International Nuclear Information System (INIS)

    Miller, R.C.; Fujikura, Toshio; Hiraoka, Toshio; Tenou, Hiromi.

    1983-06-01

    The herbicide, paraquat (methyl viologen, 1-1' dimethy1-4, 4'-bipyridinium dichloride), stimulates the production of superoxide anion (O 2 sup(-.)) in aerobic cells and therefore mimics some effects of ionizing radiation. In addition, concentrations of cellular glutathione are reduced by reaction with O 2 sup(-.). It is reported here that paraquat, toxic in its own right to aerobic cells, acts as a radiosensitizer when cells are exposed to nontoxic concentrations of the drug prior to and during irradiation. The radiomimetic effect of paraquat, alone and in combination with X-rays, was examined. Paraquat affects aerated cells (hamster lung V79 cells) in a dose-dependent manner. Doses in excess of 1 mM for two hours cause significant cell killing. In combination with radiation, sublethal doses of paraquat, given for two hours prior to irradiation, enhance the lethal effects of radiation. However, if cells are exposed to the same concentration of paraquat following irradiation, no additional lethal effect is observed. Paraquat is a useful tool to study the effects of O 2 sup(-.) and may lead to better understanding of the mechanisms of radiation-induced energy deposition in cells. (author)

  17. Radiosensitivity of protoplasts of orange (Citrus sinensis)

    International Nuclear Information System (INIS)

    Goldman, M.H.S.; Ando, A.

    1990-01-01

    Full text: The Radiation Genetics Section of the Centre for Nuclear Energy in Agriculture (CENA), University of Sao Paulo, is utilising both ''in vivo'' and ''in vitro'' methods for mutation induction in Citrus, cv. ''Pera'', aiming at resistance to citrus canker. The experiments carried out so far determined the methodology to isolate protoplasts and their sensitivity to gamma-rays. Regarding the culture of protoplasts from embryogenic callus, the best experimental conditions were: enzymatic digestion for 5 h on a medium containing cellulase (307.6 mg/10 ml), macerozyme (30.3 mg/10 ml), mannitol (328.0 mM) and sucrose (336.2 mM) as osmotic stabilisers. The isolation efficiency of 1.2x10 6 viable protoplasts/g will make it possible to use protoplasts in mutation breeding. To determine radiosensitivity of protoplasts, gamma-irradiation from 60 Co source was conducted 42 h after their isolation. This time interval is recommended because during this period protoplasts will reach the stage prior to or at the first mitotic division. Survivals were determined by metylen-blue dyeing, and the LD 50 was found to be around 37.5 Gy. Any difference compared with other authors might be due to different genotypes used or different methods of calculation of survival. (author)

  18. Radiosensitivity, radio-curability and DNA repair

    International Nuclear Information System (INIS)

    Vogin, G.

    2011-01-01

    Improvements in accuracy stand as the heart of the success of today's radiotherapy. The dose may be delivered with a sub millimetric accuracy, may also conform to complex shapes, or track external and internal organ motions. In parallel, we may increase the tumour's radio-curability by modulating the biological effects generated by ionizing radiation into the patient. It was precisely the topic of the 2009 Lucien-Mallet prize organized by the French Society for Radiation Oncology (SFRO) and the Centre Antoine-Beclere under the auspices of the Fondation de France. In this review we will precisely describe the integrated molecular response to ionizing radiations. Starting from early observations, we are going to introduce the concept of cellular radiosensitivity as the global response of the irradiated cell. We will then focus into the cell and especially its nucleus. We will describe here the most complex and deleterious radioinduced damages. In the next chapter, we will dissect the molecular pathway that aims to detect and repair the previous lesions. The last part of the review will finally deal with the diagnostic, prognostic and therapeutic impacts emerging from the alliance between clinical and molecular radiobiology. (author)

  19. Radiosensitivity of cultured insect cells: I. Lepidoptera

    International Nuclear Information System (INIS)

    Koval, T.M.

    1983-01-01

    The radiosensitivity of five lepidopteran insect cell lines representing five different genera has been investigated. These lines are: (1) TN-368, Trichoplusia ni; (2) IPLB-SF-1254, Spodoptera frugiperda; (3) IPLB-1075, Heliothis zea; (4) MRRL-CHl, clone GVl, Manduca sexta; and (5) IAL-PID2, Plodia interpunctella. The cell lines grew at different rates and had population doubling times that ranged from 19 to 52 hr. All of the lines are highly heteroploid and have approximate chromosome numbers near or above 100. The chromosomes are very small. All of the lines are extremely radioresistant; cell populations are able to recover from 260 kVp X-ray exposures up to and including 400 Gy, the highest dose examined. Cell survival curves were obtainable for only the TN-368 and IPLB-SF-1254 lines. The TN-368 cells displayed a biphasic survival response with D 0 , d/sub q/, and n values of 65.7 and 130.2 Gy, 9.0 and -36.1 Gy, and 1.2 and 0.8, respectively, for the steep and shallow portions of the curve. The IPLB-SF-1254 cells had a D 0 of 63.9 Gy. D/sub q/ of 19.0 Gy, and n value of 1.4. These studies provide definitive evidence of the radioresistance of lepidopteran cells, and suggest that this radioresistance is a characteristic of lepidopteran insects

  20. Intranuclear Delivery of a Novel Antibody-Derived Radiosensitizer Targeting the DNA-Dependent Protein Kinase Catalytic Subunit

    Energy Technology Data Exchange (ETDEWEB)

    Xiong Hairong [Institute of Molecular Medicine and Genetics, Georgia Health Sciences University, Augusta, GA (Georgia); State Key Laboratory of Virology, Institute of Medical Virology, Wuhan University School of Medicine, Wuhan (China); Lee, Robert J. [Division of Pharmaceutics, College of Pharmacy, Ohio State University, Columbus, OH (United States); Haura, Eric B. [Thoracic Oncology and Experimental Therapeutics Programs, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL (United States); Edwards, John G. [Apeliotus Technologies, Inc., Atlanta, GA (United States); Dynan, William S. [Institute of Molecular Medicine and Genetics, Georgia Health Sciences University, Augusta, GA (Georgia); Li Shuyi, E-mail: sli@georgiahealth.edu [Institute of Molecular Medicine and Genetics, Georgia Health Sciences University, Augusta, GA (Georgia); Apeliotus Technologies, Inc., Atlanta, GA (United States)

    2012-07-01

    Purpose: To inhibit DNA double-strand break repair in tumor cells by delivery of a single-chain antibody variable region fragment (ScFv 18-2) to the cell nucleus. ScFv 18-2 binds to a regulatory region of the DNA-dependent protein kinase (DNA-PK), an essential enzyme in the nonhomologous end-joining pathway, and inhibits DNA end-joining in a cell-free system and when microinjected into single cells. Development as a radiosensitizer has been limited by the lack of a method for intranuclear delivery to target cells. We investigated a delivery method based on folate receptor-mediated endocytosis. Methods and Materials: A recombinant ScFv 18-2 derivative was conjugated to folate via a scissile disulfide linker. Folate-ScFv 18-2 was characterized for its ability to be internalized by tumor cells and to influence the behavior of ionizing radiation-induced repair foci. Radiosensitization was measured in a clonogenic survival assay. Survival curves were fitted to a linear-quadratic model, and between-group differences were evaluated by an F test. Sensitization ratios were determined based on mean inhibitory dose. Results: Human KB and NCI-H292 lung cancer cells treated with folate-conjugated ScFv 18-2 showed significant radiosensitization (p < 0.001). Sensitization enhancement ratios were 1.92 {+-} 0.42 for KB cells and 1.63 {+-} 0.13 for NCI-H292 cells. Studies suggest that treatment inhibits repair of radiation-induced DSBs, as evidenced by the persistence of {gamma}-H2AX-stained foci and by inhibition of staining with anti-DNA-PKcs phosphoserine 2056. Conclusions: Folate-mediated endocytosis is an effective method for intranuclear delivery of an antibody-derived DNA repair inhibitor.

  1. Preclinical evaluation of sunitinib, a multi-tyrosine kinase inhibitor, as a radiosensitizer for human prostate cancer

    International Nuclear Information System (INIS)

    Brooks, Colin; Sheu, Tommy; Bridges, Kathleen; Mason, Kathy; Kuban, Deborah; Mathew, Paul; Meyn, Raymond

    2012-01-01

    Many prostate cancers demonstrate an increased expression of growth factor receptors such as vascular endothelial growth factor receptor (VEGFR) and platelet derived growth factor receptor (PDGFR) which have been correlated with increased resistance to radiotherapy and poor prognosis in other tumors. Therefore, response to radiation could potentially be improved by using inhibitors of these abnormally activated pathways. We have investigated the radiosensitizing effects of sunitinib, a potent, multi-tyrosine kinase inhibitor of the VEGFR and PDGFR receptors, on human prostate cancer cells. The radiosensitizing effects of sunitinib were assessed on human prostate cancer cell lines DU145, PC3 and LNCaP by clonogenic assay. Sunitinib’s ability to inhibit the activities of its key targets was determined by immunoblot analysis. The radiosensitizing effects of sunitinib in vivo were tested on human tumor xenografts growing in nude mice where response was assessed by tumor growth delay. Clonogenic survival curve assays for both DU145 and PC3 cells showed that the surviving fraction at 2 Gy was reduced from 0.70 and 0.52 in controls to 0.44 and 0.38, respectively, by a 24 hr pretreatment with 100 nM sunitinib. LNCaP cells were not radiosensitized by sunitinib. Dose dependent decreases in VEGFR and PDGFR activation were also observed following sunitinib in both DU145 and PC3 cells. We assessed the ability of sunitinib to radiosensitize PC3 xenograft tumors growing in the hind limb of nude mice. Sunitinib given concurrently with radiation did not prolong tumor growth delay. However, when animals were treated with sunitinib commencing the day after fractionated radiation was complete, tumor growth delay was enhanced compared to radiation alone. We conclude, based on the in vivo results, that sunitinib and radiation do not interact directly to radiosensitize the PC3 tumor cells in vivo as they did in vitro. The fact that tumor growth delay was enhanced when sunitinib was

  2. A review of human cell radiosensitivity in vitro

    International Nuclear Information System (INIS)

    Deschavanne, Patrick J.; Fertil, Bernard

    1996-01-01

    The survival curves of 694 human cell lines irradiated in exponentially growing phase in vitro were collected from the literature. Among them, 271 were derived from tumors, 423 were nontransformed fibroblasts and other normal cell strains from healthy people or people with some genetic disorders. Seventy-six different cell types are identified, and a specific radiosensitivity could be associated with each, using D-bar and surviving fraction at 2 Gy. Technical factors such as culture medium, feeder cells, and scoring method were found to affect intrinsic radiosensitivity. In particular, the cell type is not a discriminating factor when cells are studied in agar. Results obtained with cells irradiated in agar must be used cautiously, depending on how the cells were prepared for the experiments. The use of feeder cells narrows the range of radiosensitivity of human cells. For cells irradiated as monolayer, it was possible to build a scale of radiosensitivity according to cell type, ranging, in terms of D-bar from 0.6 Gy for the most sensitive cell lines to more than 4 Gy for the most resistant. Considering that, in most cases, we could estimate the variation of radiosensitivity within each cell type, our classification among cell types can be used by researchers to place their results in the context of the literature

  3. Randomness in the network inhibits cooperation based on the bounded rational collective altruistic decision

    International Nuclear Information System (INIS)

    Ohdaira, Tetsushi

    2014-01-01

    Previous studies discussing cooperation employ the best decision that every player knows all information regarding the payoff matrix and selects the strategy of the highest payoff. Therefore, they do not discuss cooperation based on the altruistic decision with limited information (bounded rational altruistic decision). In addition, they do not cover the case where every player can submit his/her strategy several times in a match of the game. This paper is based on Ohdaira's reconsideration of the bounded rational altruistic decision, and also employs the framework of the prisoner's dilemma game (PDG) with sequential strategy. The distinction between this study and the Ohdaira's reconsideration is that the former covers the model of multiple groups, but the latter deals with the model of only two groups. Ohdaira's reconsideration shows that the bounded rational altruistic decision facilitates much more cooperation in the PDG with sequential strategy than Ohdaira and Terano's bounded rational second-best decision does. However, the detail of cooperation of multiple groups based on the bounded rational altruistic decision has not been resolved yet. This study, therefore, shows how randomness in the network composed of multiple groups affects the increase of the average frequency of mutual cooperation (cooperation between groups) based on the bounded rational altruistic decision of multiple groups. We also discuss the results of the model in comparison with related studies which employ the best decision. (paper)

  4. Randomness in the network inhibits cooperation based on the bounded rational collective altruistic decision

    Science.gov (United States)

    Ohdaira, Tetsushi

    2014-07-01

    Previous studies discussing cooperation employ the best decision that every player knows all information regarding the payoff matrix and selects the strategy of the highest payoff. Therefore, they do not discuss cooperation based on the altruistic decision with limited information (bounded rational altruistic decision). In addition, they do not cover the case where every player can submit his/her strategy several times in a match of the game. This paper is based on Ohdaira's reconsideration of the bounded rational altruistic decision, and also employs the framework of the prisoner's dilemma game (PDG) with sequential strategy. The distinction between this study and the Ohdaira's reconsideration is that the former covers the model of multiple groups, but the latter deals with the model of only two groups. Ohdaira's reconsideration shows that the bounded rational altruistic decision facilitates much more cooperation in the PDG with sequential strategy than Ohdaira and Terano's bounded rational second-best decision does. However, the detail of cooperation of multiple groups based on the bounded rational altruistic decision has not been resolved yet. This study, therefore, shows how randomness in the network composed of multiple groups affects the increase of the average frequency of mutual cooperation (cooperation between groups) based on the bounded rational altruistic decision of multiple groups. We also discuss the results of the model in comparison with related studies which employ the best decision.

  5. Contributions concerning radiosensitivity proffered by the basic sciences to clinical radiation therapy

    International Nuclear Information System (INIS)

    Caputo, A.

    1974-01-01

    Basic concepts of radiosensitivity are reviewed. Some topics discussed are: probability of lethal injury as a dose dependent function; mutations resulting from radiation damage to DNA; relation of cell radiosensitivity to chromosome volume; relation of molecular structure of DNA to relative radiosensitivity of the organism; repair replication of DNA following uv and x irradiation of Escherichia coli and mammalian cells; and relation of the cell cycle to radiosensitivity. (U.S.)

  6. Targeting Phosphatidylinositol 4-Kinase IIIα for Radiosensitization: A Potential Model of Drug Repositioning Using an Anti-Hepatitis C Viral Agent

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Jeanny [Department of Radiation Oncology, Graduate School of Medicine, Seoul National University, Seoul (Korea, Republic of); Kim, Dan Hyo; Park, Ji Min [Medical Science Research Institute, Seoul National University Bundang Hospital, Seongnam (Korea, Republic of); Park, Young Hee [Department of Radiation Oncology, Graduate School of Medicine, Seoul National University, Seoul (Korea, Republic of); Hwang, Yeo Hyun [Medical Science Research Institute, Seoul National University Bundang Hospital, Seongnam (Korea, Republic of); Wu, Hong-Gyun [Department of Radiation Oncology, Graduate School of Medicine, Seoul National University, Seoul (Korea, Republic of); Institute of Radiation Medicine, Seoul National University, Seoul (Korea, Republic of); Shin, Kyung Hwan [Department of Radiation Oncology, Graduate School of Medicine, Seoul National University, Seoul (Korea, Republic of); Kim, In Ah, E-mail: inah228@snu.ac.kr [Department of Radiation Oncology, Graduate School of Medicine, Seoul National University, Seoul (Korea, Republic of); Medical Science Research Institute, Seoul National University Bundang Hospital, Seongnam (Korea, Republic of); Institute of Radiation Medicine, Seoul National University, Seoul (Korea, Republic of); Cancer Research Institute, Seoul National University, Seoul (Korea, Republic of)

    2016-11-15

    Purpose: To investigate which isotype of phosphatidylinositol 4-kinase (PI4K) may affect radiosensitivity and examine whether anti–hepatitis C viral (HCV) agents, some of which have been shown to inhibit PI4K IIIα activity, could be repositioned as a radiosensitizer in human cancer cells. Methods and Materials: U251, BT474, and HepG2 cell lines and normal human astrocyte were used. Ribonucleic acid interference, clonogenic assays, Western blotting, immunofluorescence, annexin V assay, lysotracker staining, and β-galactosidase assay were performed. Results: Of the 4 PI4K isotypes, specific inhibition of IIIα increased radiosensitivity. For pharmacologic inhibition of PI4K IIIα, we screened 9 anti-HCV agents by half-maximal inhibitory concentration assay. Simeprevir was selected, and its inhibition of PI4K IIIα activity was confirmed. Combination of simeprevir treatment and radiation significantly attenuated expression of phospho-phospho-PKC and phospho-Akt and increased radiation-induced cell death in tested cell lines. Pretreatment with simeprevir prolonged γH2AX foci formation and down-regulation of phospho-DNA-PKcs, indicating impairment of nonhomologous end-joining repair. Cells pretreated with simeprevir exhibited mixed modes of cell death, including apoptosis and autophagy. Conclusion: These data demonstrate that targeting PI4K IIIα using an anti-HCV agent is a viable approach to enhance the therapeutic efficacy of radiation therapy in various human cancers, such as glioma, breast, and hepatocellular carcinoma.

  7. Isolation and characterization of a radiosensitive Chinese hamster ovary cell line

    International Nuclear Information System (INIS)

    Fuller, L.F.

    1987-01-01

    A x-ray sensitive Chinese hamster ovary cell line was isolated using a semi-automated procedure in which mutagenized CHO cells were allowed to form colonies on top of agar, x-irradiated, then photographed at two later times. Comparison of the photographs allowed the identification of colonies which displayed significant growth arrest. One of the colonies identified in this manner produced a stable, radiosensitive line. This cell line is normal in x-ray induced inhibition of DNA synthesis, and single- and double-strand break repair, and is moderately sensitive to ethyl methane sulfonate and UV light. The sensitive line performs only half as much x-ray-induced repair replication as the parental line and this deficiency is believed to be the primary cause of its radiosensitivity. The sensitive line produces significantly higher numbers of x-ray-induced chromosome and chromatid aberrations including chromatid aberrations following exposure during the G 1 phase of the cell cycle. The line is hypomutable compared to the parental line with x-ray exposure inducing only one-third as many 6-thioguanine resistant colonies

  8. Radiosensitization of head and neck cancer cells by the phytochemical agent sulforaphane

    International Nuclear Information System (INIS)

    Kotowski, Ulana; Heiduschka, Gregor; Brunner, Markus; Fahim, Tammer; Thurnher, Dietmar; Czembirek, Cornelia; Eder-Czembirek, Christina; Schmidt, Rainer

    2011-01-01

    Sulforaphane is a naturally occurring compound found in broccoli and other cruciferous vegetables. Recently it gained attention because of its antiproliferative properties in many cancer cell lines. The aim of this study was to investigate whether sulforaphane could act as a radiosensitizer in head and neck squamous cell carcinoma cell lines. Four head and neck squamous cell carcinoma cell lines (i.e., (HNSCC) SCC9, SCC25, CAL27, and FADU) were treated with sulforaphane and subsequently irradiated. Then proliferation and clonogenic assays were performed. Apoptosis was detected by flow cytometry. Possible regulation of Akt and Mcl-1 was investigated by western blotting. Sulforaphane and radiation in combination leads to stronger inhibition of cell proliferation and of clonogenic survival than each treatment method alone. Western blot analysis of Akt and Mcl-1 showed no changed expression. Sulforaphane is a promising agent in the treatment of head and neck cancer due to its antiproliferative and radio-sensitizing properties. A combination of sulforaphane and radiation decreases clonogenic survival. Apoptosis is not regulated through Akt or the Mcl-1 protein. (orig.)

  9. Radiosensitization of head and neck cancer cells by the phytochemical agent sulforaphane

    Energy Technology Data Exchange (ETDEWEB)

    Kotowski, Ulana; Heiduschka, Gregor; Brunner, Markus; Fahim, Tammer; Thurnher, Dietmar [Medical University of Vienna (Austria). Dept. of Otorhinolaryngology, Head and Neck Surgery; Czembirek, Cornelia; Eder-Czembirek, Christina [Medical University of Vienna (Austria). Dept. of Cranio-, Maxillofacial and Oral Surgery; Schmidt, Rainer [Medical University of Vienna (Austria). Dept. of Radiotherapy and -biology

    2011-09-15

    Sulforaphane is a naturally occurring compound found in broccoli and other cruciferous vegetables. Recently it gained attention because of its antiproliferative properties in many cancer cell lines. The aim of this study was to investigate whether sulforaphane could act as a radiosensitizer in head and neck squamous cell carcinoma cell lines. Four head and neck squamous cell carcinoma cell lines (i.e., (HNSCC) SCC9, SCC25, CAL27, and FADU) were treated with sulforaphane and subsequently irradiated. Then proliferation and clonogenic assays were performed. Apoptosis was detected by flow cytometry. Possible regulation of Akt and Mcl-1 was investigated by western blotting. Sulforaphane and radiation in combination leads to stronger inhibition of cell proliferation and of clonogenic survival than each treatment method alone. Western blot analysis of Akt and Mcl-1 showed no changed expression. Sulforaphane is a promising agent in the treatment of head and neck cancer due to its antiproliferative and radio-sensitizing properties. A combination of sulforaphane and radiation decreases clonogenic survival. Apoptosis is not regulated through Akt or the Mcl-1 protein. (orig.)

  10. Roscovitine strongly enhances the effect of olaparib on radiosensitivity for HPV neg. but not for HPV pos. HNSCC cell lines.

    Science.gov (United States)

    Ziemann, Frank; Seltzsam, Steve; Dreffke, Kristin; Preising, Stefanie; Arenz, Andrea; Subtil, Florentine S B; Rieckmann, Thorsten; Engenhart-Cabillic, Rita; Dikomey, Ekkehard; Wittig, Andrea

    2017-12-01

    At present, advanced stage human Papillomavirus (HPV) negative and positive head and neck squamous cell carcinoma (HNSCC) are treated by intense multimodal therapy that includes radiochemotherapy, which are associated with relevant side effects. Patients with HPV positive tumors possess a far better prognosis than those with HPV negative cancers. Therefore, new therapeutic strategies are needed to improve the outcome especially of the latter one as well as quality of life for all HNSCC patients. Here we tested whether roscovitine, an inhibitor of cyclin-dependent kinases (CDKs), which hereby also blocks homologous recombination (HR), can be used to enhance the radiation sensitivity of HNSCC cell lines. In all five HPV negative and HPV positive cell lines tested, roscovitine caused inhibition of CDK1 and 2. Surprisingly, all HPV positive cell lines were found to be defective in HR. In contrast, HPV negative strains demonstrated efficient HR, which was completely suppressed by roscovitine. In line with this, for HPV negative but not for HPV positive cell lines, treatment with roscovitine resulted in a pronounced enhancement of the radiation-induced G2 arrest as well as a significant increase in radiosensitivity. Due to a defect in HR, all HPV positive cell lines were efficiently radiosensitized by the PARP-1 inhibitor olaparib. In contrast, in HPV negative cell lines a significant radiosensitization by olaparib was only achieved when combined with roscovitine.

  11. Enhanced intrinsic radiosensitivity after treatment with stereotactic radiosurgery for an acoustic neuroma

    International Nuclear Information System (INIS)

    Adams, Gerard; Martin, Olga A.; Roos, Daniel E.; Lobachevsky, Pavel N.; Potter, Andrew E.; Zacest, Andrew C.; Bezak, Eva; Bonner, William M.; Martin, Roger F.; Leong, Trevor

    2012-01-01

    Enhanced radiosensitivity is an uncommon phenomenon attributable to deficient DNA repair after radiotherapy which can be assessed with the γ-H2AX assay. Reports of radiosensitivity after stereotactic radiosurgery (SRS) are uncommon. We describe a case where the clinical, radiological and laboratory findings suggest enhanced radiosensitivity after SRS for an acoustic neuroma.

  12. Coculture with astrocytes reduces the radiosensitivity of glioblastoma stem-like cells and identifies additional targets for radiosensitization

    International Nuclear Information System (INIS)

    Rath, Barbara H; Wahba, Amy; Camphausen, Kevin; Tofilon, Philip J

    2015-01-01

    Toward developing a model system for investigating the role of the microenvironment in the radioresistance of glioblastoma (GBM), human glioblastoma stem-like cells (GSCs) were grown in coculture with human astrocytes. Using a trans-well assay, survival analyses showed that astrocytes significantly decreased the radiosensitivity of GSCs compared to standard culture conditions. In addition, when irradiated in coculture, the initial level of radiation-induced γH2AX foci in GSCs was reduced and foci dispersal was enhanced suggesting that the presence of astrocytes influenced the induction and repair of DNA double-strand breaks. These data indicate that astrocytes can decrease the radiosensitivity of GSCs in vitro via a paracrine-based mechanism and further support a role for the microenvironment as a determinant of GBM radioresponse. Chemokine profiling of coculture media identified a number of bioactive molecules not present under standard culture conditions. The gene expression profiles of GSCs grown in coculture were significantly different as compared to GSCs grown alone. These analyses were consistent with an astrocyte-mediated modification in GSC phenotype and, moreover, suggested a number of potential targets for GSC radiosensitization that were unique to coculture conditions. Along these lines, STAT3 was activated in GSCs grown with astrocytes; the JAK/STAT3 inhibitor WP1066 enhanced the radiosensitivity of GSCs under coculture conditions and when grown as orthotopic xenografts. Further, this coculture system may also provide an approach for identifying additional targets for GBM radiosensitization

  13. Radiosensitivities of cultured barley of different type (Hordeum vulgare)

    International Nuclear Information System (INIS)

    Wang Cailian; Shen Mei; Xu Gang; Zhao Kongnan

    1990-01-01

    The dormant seeds (with 13% moisture) of 47 barley varieties were irradiated with various doses (0-40 krad) of 137 Cs γ-rays. The radiosensitivities of naked barley was significantly higher than that of hulled barley. The sensitive coefficients of seedling height were 0.04945 and 0.03667 for naked barley and hulled barley, respectively. The radiosensitivity of four-row naked barley was significantly higher than that of two-row hulled barley and six-row hulled barley. 47 varieties studied could be divided into five types with different radiosensitivities, i.e. extreme resistant, resistant, intermediate, sensitive and extreme sensitive. It was also found that the dose-effect curves of cell nucleus volume had a peal at 30 krad

  14. Leukocyte apoptosis as a predictor of radiosensitivity in Fanconi anemia

    International Nuclear Information System (INIS)

    Petrovic, Sandra; Leskovac, Andreja; Joksic, Ivana; Filipovic, Jelena; Joksic, Gordana; Vujic, Dragana; Guc-Scekic, Marija

    2013-01-01

    Fanconi anemia (FA) is a rare cancer-prone genetic disease characterized by impaired oxygen metabolism and defects in DNA damage repair. Response of FA cells to ionizing radiation has been an issue intensively debated in the literature. To study in vitro radiosensitivity in patients suffering from FA and their parents (heterozygous carriers), we determined radiation-induced leukocyte apoptosis using flow cytometry. As TP53 gene is involved in the control of apoptosis, we studied its status in FA lymphocytes using dual colour fluorescence in situ hybridization (FISH). FA patients and female heterozygous carriers display radiosensitive response to ionizing radiation seen as abnormal elimination of cells via apoptosis. By employment of FISH, the TP53 allele loss in FA lymphocytes was not observed. In diseases related to oxidative stress, determination of radiation-induced apoptosis is the method of choice for testing the radiosensitivity. (author)

  15. Insulin-like growth factor stimulation increases radiosensitivity of a pancreatic cancer cell line through endoplasmic reticulum stress under hypoxic conditions

    International Nuclear Information System (INIS)

    Isohashi, Fumiaki; Endo, Hiroko; Mukai, Mutsuko; Inoue, Masahiro; Inoue, Takehiro

    2008-01-01

    Tumor hypoxia is an obstacle to radiotherapy. Radiosensitivity under hypoxic conditions is determined by molecular oxygen levels, as well as by various biological cellular responses. The insulin-like growth factor (IGF) signaling pathway is a widely recognized survival signal that confers radioresistance. However, under hypoxic conditions the role of IGF signaling in radiosensitivity is still poorly understood. Here, we demonstrate that IGF-II stimulation decreases clonogenic survival under hypoxic conditions in the pancreatic cancer cell lines AsPC-1 and Panc-1, and in the human breast cancer cell line MCF-7. IGF treatment under hypoxic conditions suppressed increased radiation sensitivity in these cell lines by pharmacologically inhibiting the phosphoinositide 3-kinase-mammalian target of rapamycin pathway, a major IGF signal-transduction pathway. Meanwhile, IGF-II induced the endoplasmic reticulum stress response under hypoxia, including increased protein levels of CHOP and ATF4, mRNA levels of CHOP, GADD34, and BiP as well as splicing levels of XBP-1. The response was suppressed by inhibiting phosphoinositide 3-kinase and mammalian target of rapamycin activity. Overexpression of CHOP in AsPC-1 cells increased radiation sensitivity by IGF-II simulation under hypoxic conditions, whereas suppression of CHOP expression levels with small hairpin RNA or a dominant negative form of a proline-rich extensin-like receptor protein kinase in hypoxia decreased IGF-induced radiosensitivity. IGF-induced endoplasmic reticulum stress contributed to radiosensitization independent of cell cycle status. Taken together, IGF stimulation increased radiosensitivity through the endoplasmic reticulum stress response under hypoxic conditions. (author)

  16. Clinical experiences with the radiosensitizer Misonidazol

    International Nuclear Information System (INIS)

    Bamberg, M.; Scherer, C.; Tamulevicius, P.; Streffer, C.

    1981-01-01

    The principle of action of sensitizers with electron affinity is explained and the development of these radiosensitizing substances up to the clinical of Misonidazol (MIS; Ro-07-0582) is shown. With special regard to the pharmacokinetic action of this substance, the therapeutic effects of MIS were examined in ten patients with brain tumors of high malignancy (400 mg/m 2 ) and four patients with oesophageal carcinomas (1 g/m 2 ), all these patients having reached the clinical phase III. Four other patients with recurrent brain tumors received a dose of 1 g/m 2 of MIS before each irradiation. Apart from slight neurotoxic and gastrointestinal side effects, the applicated doses of MIS were generally well tolerated. Only in one case a generalized maculopapular exanthema developed which regressed completely within few days. No correlation could be found between the subjective side effects and the plasma values determined by means of high pressure liquid chromatography (HPLC). After one to four hours following oral application, the maximum plasma concentrations were measured, the half-life (T 1/2) varying in all patients between five and ten hours. It was not possible to demonstrate an influence of dexamethasone on the plasma concentration of half-life of MIS in the brain tumor patients. The cerebrospinal fluid concentrations of MIS which may be used as an index for the concentrations in brain tumors, are closely correlated with the corresponding plasma values. There was no correlation between MIS concentrations in plasma and saliva, so that the determination of MIS in the saliva cannot be recommended as a routine method for control examinations. (orig.) [de

  17. Radiosensitization of hypoxic tumor cells in vitro by nitric oxide

    International Nuclear Information System (INIS)

    Griffin, Robert J.; Makepeace, Carol M.; Hur, Won-Joo; Song, Chang W.

    1996-01-01

    Purpose: The effects of nitric oxide (NO) on the radiosensitivity of SCK tumor cells in oxic and hypoxic environments in vitro were studied. Methods and Materials: NO was delivered to cell suspensions using the NO donors 2,2-diethyl-1-nitroso-oxyhydrazine sodium salt (DEA/NO), and a spermine/nitric oxide complex (SPER/NO), which release NO at half-lives of 2.1 min and 39 min at pH 7.4, respectively. The cells were suspended in media containing DEA/NO or SPER/NO for varying lengths of time under oxic or hypoxic conditions, irradiated, and the clonogenicity determined. Results: Both compounds markedly radiosensitized the hypoxic cells. The drug enhancement ratios (DER) for 0.1, 1.0, and 2.0 mM DEA/NO were 2.0, 2.3 and 3.0, respectively, and those for 0.1, 1.0, and 2.0 mM SPER/NO were 1.6, 2.3, and 2.8, respectively. Aerobic cells were not radiosensitized by DEA/NO or SPER/NO. When DEA/NO and SPER/NO were incubated in solution overnight to allow release of NO, they were found to have no radiosensitizing effect under hypoxic or oxic conditions indicating the sensitization by the NO donors was due to the NO molecule released from these drugs. At the higher concentrations, SPER/NO was found to be cytotoxic in aerobic conditions but not in hypoxic conditions. DEA/NO was only slightly toxic to the cells in both aerobic and hypoxic conditions. Conclusions: NO released from NO donors DEA/NO and SPER/NO is as effective as oxygen to radiosensitize hypoxic cells in vitro. Its application to the radiosensitization of hypoxic cells in solid tumors remains to be investigated

  18. Skin test of radiosensitivity. Application to Fanconi anemia

    International Nuclear Information System (INIS)

    Dutreix, J.; Gluckman, E.

    1983-01-01

    A test of skin radiosensitivity is described. It is achieved by irradiating small skin fields (15 mm in diameter) with 50 kV X-rays. The radiosensitivity is evaluated from the skin reaction observed for a single acute dose of 8 and 10 Gy; it is considered increased if the reaction for 10 Gy exceeds the desquamation threshold, and scored according to the observed reaction. The test includes an evaluation of the cellular repair, assessed on the comparison of the reactions for single dose and split irradiation. The time of the reaction peak is also reported. Abnormal reactions have been observed on 4 out of 8 patients with Fanconi Anemia

  19. Skin test of radiosensitivity. Application to Fanconi anemia

    Energy Technology Data Exchange (ETDEWEB)

    Dutreix, J. (Institut Gustave-Roussy, 94 - Villejuif (France)); Gluckman, E. (Centre Hayem, Hopital St.-Louis, 75 Paris (France))

    1983-01-01

    A test of skin radiosensitivity is described. It is achieved by irradiating small skin fields (15 mm in diameter) with 50 kV X-rays. The radiosensitivity is evaluated from the skin reaction observed for a single acute dose of 8 and 10 Gy; it is considered increased if the reaction for 10 Gy exceeds the desquamation threshold, and scored according to the observed reaction. The test includes an evaluation of the cellular repair, assessed on the comparison of the reactions for single dose and split irradiation. The time of the reaction peak is also reported. Abnormal reactions have been observed on 4 out of 8 patients with Fanconi Anemia.

  20. Parotid radiosensitivity changes: a temporal relation to glandular circadian rhythms

    International Nuclear Information System (INIS)

    El-Mofty, S.K.; Hovenga, T.L.; Russell, J.E.; Simmons, D.J.

    1982-01-01

    The radiosensitivity of the rat parotid gland to X-radiation increased considerably towards the end of the daily light span (0800-2000 hours) and to a lesser extent before the onset of that period. The major sensitivity peak occurred at 1600 hours and coincides with a diurnal nadir in the rates of protein and RNA synthesis. The minor peak occurred at 0400 hours and was temporally related to a daily period of maximal secretory activity. It is suggested that suboptimal repair and secretion-linked cellular perturbations might contribute to the pathogenesis of the circadian increases in radiosensitivity of parotid cells. (author)

  1. Radiosensitivity of continuous cultures: experiments with diploid yeast

    International Nuclear Information System (INIS)

    Kiefer, J.; Wagner, E.

    1975-01-01

    To study the influence of systems parameters on the radiosensitivity of cell populations, stationary chemostat cultures of diploid yeast with different dilution rates were γ-irradiated. Proliferation and budding kinetics were investigated and the doses necessary to eliminate the entire population determined as a function of dilution rate. It was found that this killing dose decreases with dilution rate in a linear manner. The radiosensitivity of the cells was shown to depend on the dilution rate which is presumably due to differing compositions of the population. (U.S.)

  2. Aeromonas caviae inhibits hepatic enzymes of the phosphotransfer network in experimentally infected silver catfish: Impairment on bioenergetics.

    Science.gov (United States)

    Baldissera, M D; Souza, C F; Verdi, C M; Dos Santos, K L M; Da Veiga, M L; da Rocha, M I U M; Santos, R C V; Vizzotto, B S; Baldisserotto, B

    2018-03-01

    Several studies have been demonstrated that phosphotransfer network, through the adenylate kinase (AK) and pyruvate kinase (PK) activities, allows for new perspectives leading to understanding of disease conditions associated with disturbances in energy metabolism, metabolic monitoring and signalling. In this sense, the aim of this study was to evaluate whether experimental infection by Aeromonas caviae alters hepatic AK and PK activities of silver catfish Rhamdia quelen. Hepatic AK and PK activities decreased in infected animals compared to uninfected animals, as well as the hepatic adenosine triphosphate (ATP) levels. Also, a severe hepatic damage was observed in the infected animals due to the presence of dilation and congestion of vessels, degeneration of hepatocytes and loss of liver parenchyma architecture and sinusoidal structure. Therefore, we have demonstrated, for the first time, that experimental infection by A. caviae inhibits key enzymes linked to the communication between sites of ATP generation and ATP utilization. Moreover, the absence of a reciprocal compensatory mechanism between these enzymes contributes directly to hepatic damage and for a severe energetic imbalance, which may contribute to disease pathophysiology. © 2017 John Wiley & Sons Ltd.

  3. Heat shock protein 90 (Hsp90) chaperone complex. A molecular target for enhancement of thermosensitivity and radiosensitivity

    International Nuclear Information System (INIS)

    Akimoto, Tetsuo; Nonaka, Tetsuo; Kitamoto, Yoshizumi; Sakurai, Hideyuki

    2002-01-01

    Heat shock protein 90 (Hsp90) is a highly conserved heat shock protein in animal and plants, and exists abundantly in the cytoplasm in unstressed condition, accounting for 1-2% in cytoplasmic proteins. Main difference of Hsp90 from other Hsps are its substrate that Hsp90 binds to. These substrates include various signal transduction proteins, kinase, steroid receptors and transcription factors, therefore, Hsp90 plays a key role in maintaining cellular signal transduction networks. Many chaperoned proteins (client proteins) of Hsp90 are associated with cellular proliferation or malignant transformation, thus Hsp90 chaperone complex has been focused as targets for cancer therapy. Among the client proteins, there are several molecules that have been defined as targets or factors for determination or enhancement of radiosensitivity or thermosensitivity. Thus, it is easily speculated that Hsp90 chaperone complex inhibitors that disrupt association of Hsp90 and client protein in combination with radiation or/and heat has potential effect on enhancement of radiosensitivity or thermosensitivity. In this paper, possible mechanisms in enhancing radiosensitivity or thermosensitivity according to the client proteins will be summarized. (author)

  4. A network approach to response inhibition: dissociating functional connectivity of neural components involved in action restraint and action cancellation

    NARCIS (Netherlands)

    Dambacher, F.; Sack, A.T.; Lobbestael, J.; Arntz, A.; Brugman, S.; Schuhmann, T.

    2014-01-01

    The ability to inhibit action tendencies is vital for adaptive human behaviour. Various paradigms are supposed to assess action inhibition and are often used interchangeably. However, these paradigms are based on different conceptualizations (action restraint vs. action cancellation) and the

  5. The discussion of method for survey the radiosensitivity of human glioma cell line SHG-44

    International Nuclear Information System (INIS)

    Li Li; Xu Changshao; Zhou Juying; Xu Xiaoting; Luo Jialin

    2005-01-01

    Objective: To investigate if thiazolyl blue colorimetric assay (MTT) and cell counting kit-8 (CCK-8) can replace clone forming assay for survey the radiosensitivity of SHG-44. Methods; Three assays was applied to examine the growth inhibition of human glioma cell line SHG-44 in eight dose groups of 0, 1, 2, 3, 4, 6, 8 and 10 Gy, and statistical research was applied to analyze the correlation between survival fraction and various doses. Results: Dose was associated with survival fraction in these three assays at some range of irradiation doseage (dose≤3 Gy). If out of the range, the relation is poor. CCK-8 has no rather superiority than MTT. Conclusion: By now clone forming assay is still the 'gold standard'. In some cases, MTT and other assays can give us some reference, but these assays still can not replace clone forming assay. (authors)

  6. Radiosensitivity is increased by knockdown of FTS in uterine cervical cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Park, Wo Yoon; Anandharaj, Arunkumar; Cinghu, Senthikumar; Kim, Won Dong [Dept. of Radiation Oncology, Chungbuk National University College of Medicine, Cheongju (Korea, Republic of); Yu, Jae Ran [Dept. of Environmental and Tropical Medicine, Konkuk University College of Medicine, Seoul (Korea, Republic of)

    2012-04-15

    Uterine cervical cancer is still the second largest cancer in women worldwide, despite of effective screening methods. Radiotherapy is used to treat all the stages of cervical cancer and more than 60% of cervical cancer patients receive radiotherapy. New therapeutic targets or approaches are needed to further increase the results of radiotherapy. In the present study, we demonstrated the radiation induced overexpression and nuclear export of FTS in cervical cancer cells. Furthermore, we showed that silencing of FTS expression with FTS shRNA enhanced radiosensitivity of cervical cancer cells, induced cell cycle arrest and apoptosis FTS is involved in radioresistance of cervical cancer. Targeted inhibition of FTS can shutdown the key elemental characteristics of cervical cancer and could lead to an effective therapeutic strategy.

  7. Radiosensitivity is increased by knockdown of FTS in uterine cervical cancer cells

    International Nuclear Information System (INIS)

    Park, Wo Yoon; Anandharaj, Arunkumar; Cinghu, Senthikumar; Kim, Won Dong; Yu, Jae Ran

    2012-01-01

    Uterine cervical cancer is still the second largest cancer in women worldwide, despite of effective screening methods. Radiotherapy is used to treat all the stages of cervical cancer and more than 60% of cervical cancer patients receive radiotherapy. New therapeutic targets or approaches are needed to further increase the results of radiotherapy. In the present study, we demonstrated the radiation induced overexpression and nuclear export of FTS in cervical cancer cells. Furthermore, we showed that silencing of FTS expression with FTS shRNA enhanced radiosensitivity of cervical cancer cells, induced cell cycle arrest and apoptosis FTS is involved in radioresistance of cervical cancer. Targeted inhibition of FTS can shutdown the key elemental characteristics of cervical cancer and could lead to an effective therapeutic strategy

  8. The use of drugs which deplete intracellular glutathione in hypoxic cell radiosensitization

    International Nuclear Information System (INIS)

    Bump, E.A.; Yu, N.Y.; Brown, J.M.

    1982-01-01

    Diethylmaleate (DEM) is a thiol-biding reagent with specificity toward glutathione. Treatment of chinese hamster ovary (CHO) cells in vitro with 2 x 10 -4 M DEM for one hour results in a decrease in glutathione content to less than 5% of control, without cytotoxicity. This treatment results in dose-modifying sensitization to radiation under hypoxic conditions, with no effect on the shoulder of the radiation survival curve. No effect on the radiation sensitivity of oxygenated cells was seen. DEM pretreatment enhances the radiosensitization of hypoxic cells by misonidazole, as well. Similar results were obtained in vivo with EMT6 tumors in BALB/c mice. Analysis of DNA damage by the alkaline elution assay indicates that DEM enhances radiation-induced single-strand breaks, but does not significantly affect repair, while diamide and N-ethylmaleimide inhibit repair, in addition to enhancing radiation-induced single-strand breaks

  9. Proteasome inhibitors block DNA repair and radiosensitize non-small cell lung cancer.

    Directory of Open Access Journals (Sweden)

    Kyle R Cron

    Full Text Available Despite optimal radiation therapy (RT, chemotherapy and/or surgery, a majority of patients with locally advanced non-small cell lung cancer (NSCLC fail treatment. To identify novel gene targets for improved tumor control, we performed whole genome RNAi screens to identify knockdowns that most reproducibly increase NSCLC cytotoxicity. These screens identified several proteasome subunits among top hits, including the topmost hit PSMA1, a component of the core 20 S proteasome. Radiation and proteasome inhibition showed synergistic effects. Proteasome inhibition resulted in an 80-90% decrease in homologous recombination (HR, a 50% decrease in expression of NF-κB-inducible HR genes BRCA1 and FANCD2, and a reduction of BRCA1, FANCD2 and RAD51 ionizing radiation-induced foci. IκBα RNAi knockdown rescued NSCLC radioresistance. Irradiation of mice with NCI-H460 xenografts after inducible PSMA1 shRNA knockdown markedly increased murine survival compared to either treatment alone. Proteasome inhibition is a promising strategy for NSCLC radiosensitization via inhibition of NF-κB-mediated expression of Fanconi Anemia/HR DNA repair genes.

  10. Neoplasms radiosensitivity: how to increase the efficiency of radiotherapy

    International Nuclear Information System (INIS)

    Calais, G.

    1991-01-01

    The hypoxia in the neoplasms is a radioresistance factor. This article is about the methods able to reduce the hypoxia in tumors: use of hyperbaric oxygen, radiosensitizers (as metronidazole), hyperthermia and modification of oxygen release in the tissues in modifying the blood flow and in reducing the hemoglobin affinity for oxygen [fr

  11. Radiosensitivity of drug-resistant human tumour xenografts

    International Nuclear Information System (INIS)

    Mattern, J.; Bak, M. Jr.; Volm, M.; Hoever, K.H.

    1989-01-01

    The radiosensitivity of three drug-resistant sublines of a human epidermoid lung carcinoma growing as xenografts in nude mice was investigated. Drug resistance to vincristine, actinomycin D and cisplatin was developed in vivo by repeated drug treatment. It was found that all three drug-resistant tumour lines were not cross-resistant to irradiation. (orig.) [de

  12. Enhancement of misonidazole radiosensitization by an inhibitor of glutathione biosynthesis

    International Nuclear Information System (INIS)

    Hodgkiss, R.J.; Middleton, R.W.

    1983-01-01

    A well known inhibitor of glutathione biosynthesis, buthione sulphoximine (S-n-butyl homocysteine sulphoximine, BSO) depletes non-protein sulphydryls (NPSH) in Chinese hamster cells in vitro, resulting in a marked increase in the radiosensitization efficiency of misonidazole. V79 379A Chinese hamster cells were maintained in suspension cultures and irradiated in monolayers using 250 kVp X-rays at a dose rate of 3.93 Gy/min. Radiosensitization by misonidazole alone gave results within 0.1 sensitizer enhancement ratio (s.e.r.) of the curve reported by Watts et al. (1980). GSH (2 mmol dm - 3 ) added to the extracellular medium resulted in a marked decrease in the radiosensitization efficiency of misonidazole, eliminating the effect at 0.1 mmol dm - 3 misonidazole (s.e.r. = 1.0 relative to nitrogen control). A marked enhancement of the radiosensitization by misonidazole was observed when the cells had been incubated with BSO (0.1 mmol dm - 3 ). BSO alone at this concentration gave s.e.r. = 1.17; misonidazole alone (0.1 mmol dm - 3 ) gave s.e.r. = 1.18 and misonidazole with BSO (both 0.1. mmol dm - 3 ) gave s.e.r. = 1.9. The BSO treatment gave little effect in aerated cells. The concentration of BSO needed to produce these effects in vitro is ca. 40-fold lower than doses tolerated by mice in repeated administrations. (U.K.)

  13. Radiosensitivity and parameters for its measurement in some cucurbits

    Energy Technology Data Exchange (ETDEWEB)

    Vishnoi, A.K.; Joshi, M.C. (Defence Research and Development Organization, Almora (India). Agricultural Research Unit)

    1981-12-01

    Treatment with gamma-rays resulted in a significant reduction in the germination percentage and root and shoot lengths in Luffa cylindrica (inn). M. Roem, Momordica charantia Linn. Lagenaria siceraria (Mol.) Standl. and Cylanthera pedata Schrad., but radiation had no significant effect on nuclear volume. Species having higher value of nuclear volume had more radiosensitivity.

  14. DNA repair and the genetic control of radiosensitivity in yeast

    International Nuclear Information System (INIS)

    Haynes, R.H.

    1975-01-01

    The following topics are discussed: advantages of yeasts for easily manipulated model systems for studies on molecular biology of eukaryotes; induction of x-ray-resistant mutants by radiations and chemicals; genetics of uv-sensitive mutants; loci of genes affecting radiosensitivity; gene interactions in multiple mutants; liquid-holding recovery; mitotic and meiotic recombination; and repair of yeast mitochondrial DNA

  15. In vivo radiosensitizing effect of nitroimidazole derivative KIN-804

    International Nuclear Information System (INIS)

    Tada, Takuhito; Nakajima, Toshifumi; Onoyama, Yasuto; Murayama, Chieko; Mori, Yomoyuki; Nagasawa, Hideko; Hori, Hitoshi; Inayama, Seiichi

    1994-01-01

    In vivo characteristics of 2-nitroimidazole-1-methylacetohydroxamate (KIN-804), which is a newly developed hypoxic cell radiosensitizer, are presented. The toxicity, pharmacokinetics, and radiosensitizing effect of KIN-804 were studied by in vivo experiments using C3H/He mice bearing the SCCVII tumor. Results were compared with misonidazole (MISO). LD 50 7 of KIN-804 and MISO were 3200 mg/kg and 2000 mg/kg, respectively. The peak concentration of KIN-804 in the tumor occurred 20 min after intraperitoneal injection and reached about 62% of the maximum concentration in the blood. The concentrations in brain and sciatic nerve were very low and clearance from sciatic nerve was rapid. Enhancement ratios of KIN-804 calculated using the growth delay method were 1.22, 1.50, and 1.71 at doses of 50, 100, and 200 mg/kg, respectively, compared with 1.36 for MISO at a dose of 100 mg/kg. In the TCD 50 assay, enhancement ratios at a dose of 200 mg/kg were 1.69 for KIN-804 and 1.52 for MISO, respectively. KIN-804 is a promising radiosensitizer since it shows less toxicity and higher radiosensitizing activity than MISO. 10 refs., 5 figs

  16. Radio-sensitizing effect of ethyl caffeate on nasopharyngeal ...

    African Journals Online (AJOL)

    3Department of Clinical Laboratory, The 5th People's Hospital of Ji'nan, Ji'nan ... Purpose: To investigate the radio-sensitizing effect of ethyl caffeate (ETF) on naso-pharyngeal ... malignant solid tumors of head and neck which ... Excess irradiation could result in severe side .... protein bands were probed with corresponding.

  17. Voltammetry of hypoxic cells radiosensitizer etanidazole radical anion in water

    Czech Academy of Sciences Publication Activity Database

    Gál, Miroslav; Hromadová, Magdaléna; Pospíšil, Lubomír; Híveš, J.; Sokolová, Romana; Kolivoška, Viliam; Kocábová, Jana

    2010-01-01

    Roč. 78, č. 2 (2010), s. 118-123 ISSN 1567-5394 R&D Projects: GA ČR GP203/09/P502 Institutional research plan: CEZ:AV0Z40400503 Keywords : etanidazole * radiosensitizer * electron transfer * voltammetry Subject RIV: CG - Electrochemistry Impact factor: 3.520, year: 2010

  18. Radiosensitivity and parameters for its measurement in some cucurbits

    International Nuclear Information System (INIS)

    Vishnoi, A.K.; Joshi, M.C.

    1981-01-01

    Treatment with gamma-rays resulted in a significant reduction in the germination percentage and root and shoot lengths in Luffa cylindrica (inn). M. Roem, Momordica charantia Linn. Lagenaria siceraria (Mol.) Standl. and Cylanthera pedata Schrad., but radiation had no significant effect on nuclear volume. Species having higher value of nuclear volume had more radiosensitivity. (author)

  19. Impacts of berberine on the growth, migration and radiosensitivity of breast cancer cells

    International Nuclear Information System (INIS)

    Zhao Chaoqian; Xu Jiaying; Jiao Yang; Hu Xudong; Che Jun; Fan Saijun

    2012-01-01

    Objective: To study the impacts of berberine on the growth, migration and radiosensitivity in human breast cancer cells. Methods: MTT assay was used to evaluate cell growth.In vitro scratch migration assay was used to determine cell migration. Annexin V assay was used to detect cell apoptosis. The distribution of cell cycle was evaluated by flow cytometry assay. Colony formation assay was used to detect the influence of berberine on cell radiosensitivity. Western blot assay was employed to measure protein expression. Results: Berberine inhibited cell growth and migration in two human breast cancer cell lines, MCF-7 and MDA-MB-231, in a dose-and time-dependent manner. Furthermore, berberine resulted in a cell cycle G 0 /G 1 arrest. Compared with control, the early apoptosis in MDA-MB-231 and MCF-7 cells treated with 40 pμmol/L of berberine was as high as 86.6% and 66.6% (t=8.79, 10.32, P<0.01), respectively. Berberine caused a dose-dependent increase in Bax and Caspase-3 protein expressions, but did not change Cyclin D1 protein expression, while suppressed the expressions of Cyclin B1 and Bcl-2 protein. As analyzed with multi-target click model fitting curves, the SER D0 of berberine-treated cells were 1.12 and 1.22 for MDA-MB-231 and MCF-7 cells respectively at the dose D 0 of X-rays. Conclusions: The berberine inhibited the growth and migration of breast cancer cells via apoptosis induction and cell cycle arrest. Moreover, berberine increases cell sensitivity to X-ray irradiation. (authors)

  20. Radiosensitizing effect of artesunate on nude mice transplanted with HeLa cells of cervical cancer

    International Nuclear Information System (INIS)

    Zhou Yuanyuan; Feng Yang; Zhang Xuguang; Zhu Wei; Ni Qianying; Geng Chong; Chen Guanglie; Luo Judong; Fan Saijun; Cao Jianping

    2011-01-01

    Objective: To investigate the radiosensitization of artesunate on nude mouse transplanted with HeLa cells,and to explore its possible mechanisms. Methods: HeLa cells were inoculated into the nude mice to establish tumor model. Mice were randomly divided into 4 groups as blank control,artesunate group, radiation group and artesunate + radiation group when average volume of tumor were about 5 mm × 5 mm× 5 mm. During the term of treatment, the volume of tumors were measured every 2 days. After 14 days treatment, the mice were killed and tumor tissues were harvested for flow cytometry to detect the alteration of cell cycle. Meanwhile, the pathological change of the tumor tissue was observed with HE staining method, and the change of expression of cycle regulatory protein Cyclin B1, Cdc2 and Wee1 were detected by Western blot. Results: The growth of tumor was significantly inhibited by artesunate combined with radiation and its inhibition rate was 72.34%. Flow cytometry results showed that the percent of cells in G 1 phase increased and G 2 phase decreased in the artesunate + radiation group compared with those in irradiation group (t=4.41, 4.12, P<0.05). The expression level of Cyclin B1 was obviously increased while that of Wee1 decreased in the artesunate + radiation compared with irradiation group. There was no difference in the expression of Cdc2 among the four groups. Conclusions: Artesunate can dramatically increase the radiosensitivity of transplanted tumor of HeLa cells. The possible mechanism might be related to the decreasing G 2 phase by regulating the expression of Cyclin B1 and Wee1. (authors)

  1. The combination of olaparib and camptothecin for effective radiosensitization

    Directory of Open Access Journals (Sweden)

    Miura Katsutoshi

    2012-04-01

    Full Text Available Abstract Background Poly (ADP-ribose polymerase-1 (PARP-1 is a key enzyme involved in the repair of radiation-induced single-strand DNA breaks. PARP inhibitors such as olaparib (KU-0059436, AZD-2281 enhance tumor sensitivity to radiation and to topoisomerase I inhibitors like camptothecin (CPT. Olaparib is an orally bioavailable inhibitor of PARP-1 and PARP-2 that has been tested in multiple clinical trials. The purpose of this study was to investigate the characteristics of the sensitizing effect of olaparib for radiation and CPT in order to support clinical application of this agent. Methods DLD-1 cells (a human colorectal cancer cell line and H1299 cells (a non-small cell lung cancer cell line with differences of p53 gene status were used. The survival of these cells was determined by clonogenic assay after treatment with drugs and X-ray irradiation. The γH2AX focus formation assay was performed to examine the influence of olaparib on induction and repair of double-stranded DNA breaks after exposure to radiation or CPT. Results A radiosensitizing effect of olaparib was seen even at 0.01 μM. Its radiosensitizing effect after exposure for 2 h was similar to that after 24 h. H1299 cells with depletion or mutation of p53 were more radioresistant than H1299 cells with wild-type p53. However, similar enhancement of radiosensitization by olaparib was observed with all of the tested cell lines regardless of the p53 status. Olaparib also sensitized cells to CPT. This sensitizing effect was seen at low concentrations of olaparib such as 0.01 μM, and its sensitizing effect was the same at both 0.01 μM and 1 μM. The combination of olaparib and CPT had a stronger radiosensitizing effect. The results of the γH2AX focus assay corresponded with the clonogenic assay findings. Conclusion Olaparib enhanced sensitivity to radiation and CPT at low concentrations and after relatively short exposure times such as 2 h. The radiosensitizing effect of olaprib

  2. The combination of olaparib and camptothecin for effective radiosensitization

    International Nuclear Information System (INIS)

    Miura, Katsutoshi; Sakata, Koh-ichi; Someya, Masanori; Matsumoto, Yoshihisa; Matsumoto, Hideki; Takahashi, Akihisa; Hareyama, Masato

    2012-01-01

    Poly (ADP-ribose) polymerase-1 (PARP-1) is a key enzyme involved in the repair of radiation-induced single-strand DNA breaks. PARP inhibitors such as olaparib (KU-0059436, AZD-2281) enhance tumor sensitivity to radiation and to topoisomerase I inhibitors like camptothecin (CPT). Olaparib is an orally bioavailable inhibitor of PARP-1 and PARP-2 that has been tested in multiple clinical trials. The purpose of this study was to investigate the characteristics of the sensitizing effect of olaparib for radiation and CPT in order to support clinical application of this agent. DLD-1 cells (a human colorectal cancer cell line) and H1299 cells (a non-small cell lung cancer cell line) with differences of p53 gene status were used. The survival of these cells was determined by clonogenic assay after treatment with drugs and X-ray irradiation. The γH2AX focus formation assay was performed to examine the influence of olaparib on induction and repair of double-stranded DNA breaks after exposure to radiation or CPT. A radiosensitizing effect of olaparib was seen even at 0.01 μM. Its radiosensitizing effect after exposure for 2 h was similar to that after 24 h. H1299 cells with depletion or mutation of p53 were more radioresistant than H1299 cells with wild-type p53. However, similar enhancement of radiosensitization by olaparib was observed with all of the tested cell lines regardless of the p53 status. Olaparib also sensitized cells to CPT. This sensitizing effect was seen at low concentrations of olaparib such as 0.01 μM, and its sensitizing effect was the same at both 0.01 μM and 1 μM. The combination of olaparib and CPT had a stronger radiosensitizing effect. The results of the γH2AX focus assay corresponded with the clonogenic assay findings. Olaparib enhanced sensitivity to radiation and CPT at low concentrations and after relatively short exposure times such as 2 h. The radiosensitizing effect of olaprib was not dependent on the p53 status of tumor cells. These

  3. Radiosensitizing effect of RHOB protein in melanoma cells

    International Nuclear Information System (INIS)

    Notcovich, C.; Grissi, C.; Sánchez Crespo, R.; Delgado, D.C.; Molinari, B.; Ibañez, I.L.; Durán, H.

    2015-01-01

    Melanoma cells are highly resistant to chemo or radiotherapy. DNA damage agents such as ionizing radiation induce apoptosis involving RhoB protein. In a great variety of tumors the levels of this protein decrease along tumor progression. RhoB is considered a tumor suppressor gene due to its antiproliferative and proapoptotic effect. Considering the aforementioned, the aim of this study was to characterize the radiobiological response of different human melanoma cell lines, and to evaluate the possible correlation between RhoB expression and radiosensitivity. The human melanoma cell lines A375, MELJ and SB2 were gamma-irradiated ( 137 Cs). Survival curves were obtained by clonogenic assay and fitted to the Linear-Quadratic (LQ) model. Radiosensitivity was evaluated by surviving fraction at 2 Gy (SF2). Results showed that MELJ was significantly more radioresistant (SF2=0.71) than A375 and SB2 (0.29 and 0.21 respectively. Expression levels of RhoB, evaluated by western blot, increased in all lines vs. non-irradiated control. SB2, the most radiosensitive cells, showed a greater induction (p<0.05) of RhoB. Finally, to study whether RhoB has a radiosensitizing effect, these cell lines were stably transfected with a wild type RhoB construction, a constitutively active RhoB mutant V14, or with the empty plasmid as control. For all cell lines higher expression level of this protein was found in RhoB or V14 transfected cells (p<0.05). Sensitization was evaluated by SF2. Significant radiosensitization was demonstrated in clones derived from A375 and SB2 ((p<0.05), while for MELJ cells, radio-sensitization was only found in clones overexpressing V14. In conclusion, the increase of RhoB in melanoma cell lines, either by radiation or transfection has a radiosensitizing effect. Thus, we propose RhoB modulation as a potential therapeutic tool to improve the radiation response of radioresistant melanoma. (authors)

  4. Potential clinical impact of normal-tissue intrinsic radiosensitivity testing

    International Nuclear Information System (INIS)

    Bentzen, Soeren M.

    1997-01-01

    A critical appraisal is given of the possible benefit from a reliable pre-treatment knowledge of individual normal-tissue sensitivity to radiotherapy. The considerations are in part, but not exclusively, based on the recent experience with in vitro colony-forming assays of the surviving fraction at 2 Gy, the SF 2 . Three strategies are reviewed: (1) to screen for rare cases with extreme radiosensitivity, so-called over-reactors, and treat these with reduced total dose, (2) to identify the sensitive tail of the distribution of 'normal' radiosensitivities, refer these patients to other treatment, and to escalate the dose to the remaining patients, or (3) to individualize dose prescriptions based on individual radiosensitivity, i.e. treating to isoeffect rather than to a specific dose-fractionation schedule. It is shown that these strategies will have a small, if any, impact on routine radiotherapy. Screening for over-reactors is hampered by the low prevalence of these among otherwise un-selected patients that leads to a low positive predictive value of in vitro radiosensitivity assays. It is argued, that this problem may persist even if the noise on current assays could be reduced to (the unrealistic value of) zero, simply because of the large biological variation in SF 2 . Removing the sensitive tail of the patient population, will only have a minor effect on the dose that could be delivered to the remaining patients, because of the sigmoid shape of empirical dose-response relationships. Finally, individualizing dose prescriptions based exclusively on information from a normal-tissue radiosensitivity assay, leads to a nearly symmetrical distribution of dose-changes that would produce a very small gain, or even a loss, of tumor control probability if implemented in the clinic. From a theoretical point of view, other strategies could be devised and some of these are considered in this review. Right now the most promising clinical use of in vitro radiosensitivity

  5. Determining and predictive factors for the tumor radiosensitivity

    International Nuclear Information System (INIS)

    Hennequin, Ch.; Quero, L.; Hennequin, Ch.; Quero, L.; Favaudon, V.

    2008-01-01

    Many predictive factors of tumor radiosensitivity have been described. Number of clonogenic cells, proliferation rate, hypoxia and intrinsic radiosensitivity are usually considered as the main parameters of tumor control. Intrinsic radiosensitivity is correlated in a first approach to the ability of the cell to detect and repair DNA damages, and so integrity of the different pathways involved in this function: P.A.R.P.-1, X.R.C.C.1, A.T.M., p 53, M.R.N. complex or B.R.C.A.1. Genetic polymorphisms of some of these genes, found in normal lymphocytes, have been correlated to late toxicity of normal tissues. But, in tumors, because of the difficulty to obtain samplings and heterogeneity, accurate molecular analysis is not possible in many cases, and no valuable test of radiosensitivity exist at this moment. For example, T.P. 53 gene has been evaluated in many studies and results regarding its potential as a predictive factor of tumor sensitivity are conflicting. Surviving fraction at 2 Gy (S.F.2) allowed a global evaluation of sensitivity, but the obtention of this parameter often takes a long time and failed in 20 to 40%. Evaluation of double-strand break repair capacity by immuno chemistry quantification of phosphorylated forms of A.T.M., H.2 A.X. or M.R.E.11 is an interesting topic. However, discovery of tumor stem cells in a number of epithelial tumors could revolutionize the understanding of radiosensitivity. Combination of genomic and functional techniques are probably essential to better predict this parameter. (authors)

  6. Reduced Social Network Drinking is Associated with Improved Response Inhibition in Women During Early Recovery from Alcohol Use Disorders: A Pilot Study.

    Science.gov (United States)

    McCutcheon, Vivia V; Luke, Douglas A; Lessov-Schlaggar, Christina N

    2016-01-01

    Social support for recovery from alcohol use disorders (AUDs) is associated with improvements in self-reported impulsive behavior in individuals treated for AUDs. We build on these findings using a behavioral task-based measure of response inhibition, a well-defined component of impulsivity, to examine the association of disinhibition with alcohol-specific social network characteristics during early recovery. Women (n = 28) were recruited from treatment for AUD within 3 to 4 weeks of their last drink and were assessed at baseline and again 3 months later. Outcome measures were level of disinhibition at baseline and change in disinhibition from baseline to follow-up, measured using a computer-based continuous performance test. The primary independent variables were level of drinking in the social network at baseline and change in network drinking from baseline to follow-up. The sample [50% black, age M (SD) = 42.3 (9.5)] reported high rates of physical and sexual abuse before age 13 (43%), psychiatric disorder (71%), drug use disorder (78%), and previous treatment (71%). More drinking in participants' social networks was associated with greater disinhibition at baseline (β = 12.5, 95% CI = 6.3, 18.7). A reduction in network drinking from baseline to follow-up was associated with reduced disinhibition (β = -6.0, 95% CI = -11.3, -0.78) independent of IQ, recent alcohol consumption, and self-reported negative urgency. This study extends previous findings of an association between social networks and self-reported impulsivity to a neurobehavioral phenotype, response inhibition, suggesting that abstinence-supporting social networks may play a role in cognitive change during early recovery from AUDs. Copyright © 2015 by the Research Society on Alcoholism.

  7. Radiosensitive effect of hypoxia-inducible factor 1α inhibitor YC-1 on hypoxic glioma SHG44 cell line

    International Nuclear Information System (INIS)

    Guo Xinwei; Lu Xueguan; Tong Liumei; Zong Tianzhou; Chen Liesong

    2011-01-01

    Objective: To investigate the radiosensitive effect of hypoxia-inducible factor 1α (HIF-1α) inhibitor YC-1 on hypoxic glioma SHG44 cell line and its related mechanism. Methods: Glioma SHG44 cell line was cultured in normoxic (20% O 2 ), continuous hypoxia (1% O 2 ) for 12 h and 24 h, continuous hypoxia plus YC-1 was performed for 12 h and 24 h, respectively. The expression of HIF-1α was assessed by Western blot. The radiosensitivity was evaluated by the survival curve, and the sublethal damage repair (SLDR) ability was measured by dose-fraction experiment. Results: HIF-1α protein levels of glioma SHG44 cells were significantly increased after hypoxic cultures for 12 h and 24 h than those of the corresponding cells cultured in normoxic, while the radiosensitivity was lower. The OER (oxygen-enhancement ratio) of SHG44 cells in hypoxia for 12 h and 24 h were 1.22 and 1.37, respectively. By the further statistical analysis it was found that SLDR ability of glioma SHG44 was increased at hypoxia, and when irradiation was carried one at the interval of 8, 10, 12 h it was statistically significant (P<0.05). HIF-1α protein levels of glioma SHG44 cells cultured in hypoxia plus YC-1 for 12 h and 24 h were decreased significantly compared to the corresponding cells cultured in hypoxia only, while the radiosensitivity was significantly increased. the EF (enhancement factor) of YC-1 for glioma SHG44 cells at hypoxia for 12 h and 24 h was 1.27. By the further statistical analysis it was also found that SLDR ability was decreased significantly for hypoxic SHG44 cells which was co-cultured with YC-1, and at the interval of 8, 10, 12 h irradiation was statistically significant (P<0.05). Conclusion: YC-1 can increase the radiosensitivity of hypoxic glioma SHG44 cell line, and its mechanism is related to SLDR inhibited by YC-1. (authors)

  8. Hematoporphyrin derivatives potentiate the radiosensitizing effects of 2-deoxy-D-glucose in cancer cells

    International Nuclear Information System (INIS)

    Dwarakanath, B.S.; Adhikari, J.S.; Jain, Viney

    1999-01-01

    Purpose: Two deoxy-D-glucose (2-DG), an inhibitor of glucose transport and glycolysis, has been shown to differentially inhibit the repair of radiation damage in cancer cells by reducing the flow of metabolic energy. Since hematoporphyrin derivatives (Hpd) inhibit certain enzymes of the respiratory metabolism, resulting in an increase in the glucose usage and glycolysis, Hpd could possibly enhance the energy-linked radiosensitizing effects of 2-DG in cancer cells. The purpose of the present work was to verify this suggestion. Methods and Materials: Two human tumor cell lines (cerebral glioma, BMG-1 and squamous cell carcinoma, 4197) and a murine tumor cell line (Ehrlich ascites tumor [EAT], F-15) in vitro were investigated. A commercially available preparation of Hpd, Photosan-3 (PS-3) was used in the present studies. Cells incubated with 0-10 μg/ml PS-3 for 0-24 h before irradiation were exposed to 2.5 Gy of Co-60 gamma rays and maintained under liquid holding conditions for 1-4 h to facilitate repair. 2-DG (0-5 mM) added at the time of irradiation was present during the liquid holding. Radiation-induced cytogenetic damage (micronuclei formation) and cell death (macrocolony assay) were analyzed as parameters of radiation response. Effects of these radiosensitizers on glucose usage and glycolysis were also studied by measuring the glucose consumption and lactate production using enzymatic assays. Results: The glucose consumption and lactate production of BMG-1 cells (0.83 and 1.43 pmole/cell/h) were twofold higher than in the 4197 cells (0.38 and 0.63 pmole/cell/h). Presence of PS-3 (10 μg/ml) enhanced the rate of glycolysis (glucose consumption and lactate production) in these cells by 35% to 65%, which was reduced by 20% to 40% in the presence of 5 mM 2-DG. In exponentially growing BMG-1 and EAT cells, presence of 2-DG (5 mM; equimolar with glucose) for 4 hours after irradiation increased the radiation-induced micronuclei formation and cell death by nearly 40

  9. Resveratrol-Induced Apoptosis and Increased Radiosensitivity in CD133-Positive Cells Derived From Atypical Teratoid/Rhabdoid Tumor

    International Nuclear Information System (INIS)

    Kao, C.-L.; Huang, P.-I; Tsai, P.-H.; Tsai, M.-L.; Lo, J.-F.; Lee, Y.-Y.; Chen, Y.-J.; Chen, Y.-W.; Chiou, S.-H.

    2009-01-01

    Purpose: CD133 has recently been proposed as a marker for cancer stem-like cells (CSC) in brain tumors. The aim of the present study was to investigate the possible role of resveratrol (RV) in radiosensitivity of CD133-positive/-negative cells derived from atypical teratoid/rhabdoid tumors (AT/RT-CD133 +/- ). Materials and Methods: AT/RT-CD133 +/- were isolated and characterized by flow cytometry and quantitative real-time reverse transcription-polymerase chain reaction, and then treated with RV at different doses. Migratory ability, colony formation, apoptotic activity, and xenotransplantation were assessed for RV alone, ionizing radiation (IR) alone, and IR with RV conditions. Results: AT/RT-CD133 + displayed enhanced self-renewal and highly coexpressed 'stem cell' genes and drug-resistant genes, in addition to showing significant resistance to chemotherapeutic agents and radiotherapy as compared with CD133 - cells. After treatment with 200 μM RV, the in vitro proliferation rates and in vivo tumor restoration abilities of ATRT-CD133 + were dramatically inhibited. Importantly, treatment with 150 μM RV can effectively inhibit the expression of drug-resistant genes in AT/RT-CD133 + , and further facilitate to the differentiation of CD133 + into CD133 - . In addition, treatment with 150 μM RV could significantly enhance the radiosensitivity and IR-mediated apoptosis in RV-treated ATRT-CD133 +/- . Kaplan-Meier survival analysis indicated that the mean survival rate of mice with ATRT-CD133 + that were treated with IR could be significantly improved when IR was combined with 150 μM RV treatment. Conclusions: AT/RT-CD133 + exhibit CSC properties and are refractory to IR treatment. Our results suggest that RV treatment plays crucial roles in antiproliferative, proapoptotic, and radiosensitizing effects on treated-CD133 +/- ; RV may therefore improve the clinical treatment of AT/RT.

  10. Heat shock protein 90 chaperone complex inhibitor enhanced radiosensitivity through modification of response to hormone and degradation of androgen receptor in hormone sensitive prostate cancer cell line

    International Nuclear Information System (INIS)

    Mitsuhashi, N.; Harashima, K.; Akimoto, T.

    2003-01-01

    It is easily speculated that androgen or androgen deprivation affects proliferative activity or radiosensitivity, but there has been enough information how androgen or androgen deprivation influences the response to radiation. In this setting, the effect of dihydrotestosterone (DHT) on cellular growth and radiosensitivity was examined in hormone-responsive human prostate cancer cell line (LnCap). The binding of androgen receptor (AR) with heat shock protein 90 (Hsp90) plays an important role in stability of the function of receptor. It was, therefore, examined how Hsp90 chaperone complex inhibitor modified the effect of DHT on radiosensitivity in addition to the effect of DHT, especially focusing on AR and its downstream signal transduction pathways. Hydroxy-flutamide (OH-flutamide) was also used to confirm the effect of activation of AR on radiosensitivity because AR of LnCap has a point mutation, leading to activation of AR caused by the binding of OH-flutamide. Radicicol was used as a Hsp90 chaperone complex inhibitor, and incubated with cells at a concentration of 500 nM. Radicicol was incubated with cells for 9 h, and cells were irradiated 1 h after the start of incubation. DHT and OH-flutamide were incubated with cells until staining. DHT or OH-flutamide resulted in stimulation of cellular growth in contrast to inhibition of cellular growth caused by higher concentrations, so that we adopted 1 nM as a concentration of DHT and 1μM as a concentration of OH-flutamide. DHT or OH-flutamide in combination with radiation resulted in slight decrease in radiosensitivity compared with radiation alone. Radicicol at a concentration of 500 nM in combination with DHT or OH-flutamide abolished decrease in radiosensitivity caused by DHT or OH-flutamide. In terms of the expression of AR, radicicol in combination with radiation and/or DHT, OH-flutamide induced degradation of AR. In consistent with degradation of AR, the expression of prostate specific antigen (PSA) decreased

  11. Review of our histological criteria for the radiosensitivity of uterine cervical cancer

    International Nuclear Information System (INIS)

    Tsukahara, Yoshiharu; Shiozawa, Kyuyo; Tsukamoto, Takashi; Sonehara, Morio; Noguchi, Hiroshi

    1975-01-01

    The determination of radiosensitiveness based on 111 operated specimens after test irradiation of 1000R was compared with that based on 64 specimens which had received biopsies seven days after irradiation. It was concluded that the determination of radiosensitiveness by local biopsy could be applied to practical use. The results of this study are listed as follows: (1) Radiosensitivity exists within tumor cells themselves before irradiation, while radiosensitiveness is a complicated change in which some reaction on the host side added to degenerated tumor cells. (2) In the determination of radio-sensitiveness, there was a good accordance of 85% between biopsies and removed specimens. (3) The followings are findings of favorable radiosensitiveness based on the removed specimens; (a) neutrocyte infiltration within cancer nests, (b) lysis of cancer nests, (c) destruction of fundus of cancer nests, (d) damages of advanced sites of cancer infiltration, (e) damages of chromatin. As unfavorable findings, (f) mitosis, (g) abundant viable cells. (4) Various histological findings within cancer nests and variation of radiosensitiveness according to various regions of the tumor often cause a discord with biopsies. (5) Many specimens which show the intermediate histological type in maturation before irradiation indicate favorable radiosensitiveness. Even if they belong to the intermediate type, the specimens in which the issued histological findings are mixed show mostly unfavorable radiosensitiveness. (6) Removed specimens can be expressed in indices of radiosensitiveness. (Ichikawa, K.)

  12. Enhancement of radiosensitivity of recombinant Ad-p53 gene on human lung adenocarcinoma cell with different p53 status

    International Nuclear Information System (INIS)

    Pang Dequan; Wang Peiguo; Wang Ping; Zhang Weiming

    2008-01-01

    Objective: To investigate the enhancement of radiosensitivity of recombinant Ad-p53 gene on human lung adenocarcinoma cell lines(A549 and GLC-82) with different p53 status in vitro. Methods: Two human lung adenocarcinoma cell lines of A549 and GLC-82 were examined on their difference in p53 status with immunohistochemistry stain and PCR-SSCP technique. Expand Ad-wtp53 was transfected into tumor cells. Clonogenic assays were performed to evaluate the inhibition effect on cell growth and the degree of sensitization to irradiation. Apoptosis and cell cycle changes were determined using the flow cytometry assay. Results: The A549 cell line presented positive P53 expression while GLC-82 negative. GLC-82 bore mutant p53 on the exon 7. The wtp53 gene could be efficiently expressed in the two cell lines and greatly inhibit the cell growth. Its efficiency didn't depend on the intrinsic p53 genetic status. After irradiation, its function of inducing G 1 arrest and apoptosis on GLC-82 cell line was much stronger than the A549 cell line. In both the A549 and GLC-82 cell lines, the combination of Ad-p53 plus radiation resulted in more apoptosis than the others. There was no significant difference between two groups. Conclusions: Ad-p53 can depress the tumor growth and enhance the radiosensitivity of human lung adenocarcinoma cells. And this effect is independent of endogenous p53 status. (authors)

  13. Modulation of Olfactory Bulb Network Activity by Serotonin: Synchronous Inhibition of Mitral Cells Mediated by Spatially Localized GABAergic Microcircuits

    Science.gov (United States)

    Schmidt, Loren J.; Strowbridge, Ben W.

    2014-01-01

    Although inhibition has often been proposed as a central mechanism for coordinating activity in the olfactory system, relatively little is known about how activation of different inhibitory local circuit pathways can generate coincident inhibition of principal cells. We used serotonin (5-HT) as a pharmacological tool to induce spiking in ensembles…

  14. Interaction of nitroaromatic radiosensitizers with irradiated polyadenylic acid as measured by an indirect immunochemical assay with specificity for the 8,5'-cycloadenosine moiety

    Energy Technology Data Exchange (ETDEWEB)

    Fuciarelli, A F; Mele, F G; Raleigh, J A

    1987-04-01

    The relative reactivity of a series of nitroaromatic radiosensitizers toward the C(5') radical intermediate leading to 8,5'-cycloadenosine formation in deoxygenated solutions of irradiated polyadenylic acid (poly A) was assessed using standard competition kinetic analysis. Formation of 8,5'-cycloadenosine was assayed by an indirect, competitive, enzyme-linked immunosorbent assay (ELISA) described in an earlier report. In the absence of oxygen, the nitroaromatics inhibit 8,5'-cyclonucleoside formation in a way which generally increases with radiosensitizer electron affinity. Although hydroxyl radical scavenging by the nitroaromatics may account for a relatively small decrease in 8,5'cyclonucleoside formation, the data suggest that oxidation of the C(5') radical intermediate is the more plausible explanation for the decreased yield of the 8,5'-cyclonucleoside with increasing nitroaromatic electron affinity.

  15. Inhibition of GRP78 abrogates radioresistance in oropharyngeal carcinoma cells after EGFR inhibition by cetuximab.

    Directory of Open Access Journals (Sweden)

    Chaonan Sun

    Full Text Available The EGFR-specific mAb cetuximab is one of the most effective treatments for oropharyngeal carcinoma, while patient responses to EGFR inhibitors given alone are modest. Combination treatment with radiation can improve the efficacy of treatment through increasing radiosensitivity, while resistance to radiation after administration of cetuximab limits its efficiency. Radiation and drugs can damage the endoplasmic reticulum (ER homeostatic state and result in ER stress (ERS, subsequently causing resistance to radiation and drugs. Whether the ERS pathway is involved in radioresistance after administration of cetuximab has not been reported. Herein, we show that cetuximab could increase the radiosensitivity of FaDu cells but not Detroit562 cells. In addition, cetuximab inhibited the radiation-induced activation of the ERS signalling pathway IRE1α/ATF6-GRP78 in FaDu cells, while this effect was absent in Detroit562 cells. Silencing GRP78 increased the radiosensitivity of oropharyngeal carcinoma cells and inhibited radiation-induced DNA double-strand-break (DSB repair and autophagy. More interestingly, silencing GRP78 abrogated resistance to cetuximab and radiation in Detroit562 cells and had a synergistic effect with cetuximab in increasing the radiosensitivity of FaDu cells. Immunohistochemistry showed that overexpression of both GRP78 and EGFR was associated with a poor prognosis in oropharyngeal carcinoma patients (P<0.05. Overall, the results of this study show that radioresistance after EGFR inhibition by cetuximab is mediated by the ERS signalling pathway IRE1α/ATF6-GRP78. This suppression was consequently unable to inhibit radiation-induced DSB repair and autophagy in oropharyngeal carcinoma cells, which conferred resistance to radiotherapy and cetuximab. These results suggest that the cooperative effects of radiotherapy and cetuximab could be further improved by inhibiting GRP78 in non-responsive oropharyngeal carcinoma patients.

  16. Use of radiosensitivity to identify irradiated fresh poultry products

    International Nuclear Information System (INIS)

    Copin, M.P.; Bourgeois, C.M.

    1991-01-01

    Microbiological comparison between irradiated and non-irradiated foodstuff has been studied for a long time as a way to detect whether a foodstuff has been irradiated or not. Generally, the proposed methods are based on the fact that ionization select species of bacteria which are recognized to be radioresistant. So reduction or elimination of known radiation sensitive microbes from the normal endogenous microflora could give an indication that the foodstuff has been irradiated, predominance of known radioresistant bacteria should be another indication. In the present work, we try to develop a test based on the radiosensitivity of the bacteria independently of their place. These first experiments show that the determination of radiosensitivity of strains isolated from a product or even of global radioresistance of mesophilic microflora could indicate if this product has been previously submitted to ionizing radiations. (4 tabs)

  17. Rockets, radiosensitizers, and RRx-001: an origin story part I.

    Science.gov (United States)

    Oronsky, Bryan; Scicinski, Jan; Ning, Shoucheng; Peehl, Donna; Oronsky, Arnold; Cabrales, Pedro; Bednarski, Mark; Knox, Susan

    2016-03-01

    From Adam and Eve, to Darwinism, origin stories attempt to fill in the blanks, connect the dots, and define the turning points that are fundamental to subsequent developments. The purpose of this review is to present the origin story of a one-of-a-kind anticancer agent, RRx-001, which emerged from the aerospace industry as a putative radiosensitizer; not since the dynamite-to-dilator transformation of nitroglycerin in 1878 or the post-World War II explosive-to-elixir conversion of hydralazine, an ingredient in rocket fuel, to an antihypertensive, an antidepressant and an antituberculant, has energetic chemistry been harnessed for therapeutic purposes. This is Part 1 of the radiosensitization story; Parts 2 and 3, which detail the crossover activity of RRx-001 as a chemosensitizer in multiple tumor types and disease states including malaria, hemorrhagic shock and sickle cell anemia, are the subject of future reviews.

  18. The dependence of fibroblast radiosensitivity on cell pH

    International Nuclear Information System (INIS)

    Veksler, A.M.; Kublik, L.N.; Degtyareva, O.V.; Ehjdus, L.Kh.

    1983-01-01

    The problem of the change of radiosensitivity of Chinese hamster fibroblasts, irradiated under aerobic and hypoxic conditions in the course of intracellular pH (pHsub(intr.)) change by means of a phosphate buffer has been studied. It has been found that pHsub(intr.) reduction considerably increases the radiosensitivity, the effect being more pronounced on hypoxic cells which is essential for radiotherapy of tumors. The survival rate of cell irradiated under hypoxia conditions does not depend on season while cell resistance in case of irradiation in open air in spring and autumn is different. The effect discovery in case of pHsub(intr.) reduction upon irradiation shows up the influence of the studied factor on repair processes

  19. The radiosensitivity of nile tilapia (Oreochromis niloticus) fingerlings

    International Nuclear Information System (INIS)

    Reyes, Michael Joseph T.; Velasco, Pia Victoria V.

    2000-04-01

    The nile tilapia (Oreochromis niloticus), a very popular fish commercially in the Philippines, was studied to determine its radiosensitivity and to see its potential as a biological indicator in aquatic ecosystems. Nile tilapia was seen to be radiosensitive. The fish were exposed to gamma-irradiation and chromosomal aberrations were induced. The various types of aberrations seen were chromatid gaps, chromosome gaps, chromatid fragments, dicentric rings, fusions, despiralizations and translocations. Among the aberrations observed, dicentric rings, fusions and chromosome gaps were strongly correlated with dosage, with only the dicentric rings increasing steadily with increasing dosage. In the course of the study, the lethal dosage 50 for nile tilapia with 18 days was determined and it was observed at 2.0 krad. The modal chromosome number was also established at 2n=44 with a karyotype exhibiting 22 pairs of acrocentric chromosomes with 2 pairs of marker chromosomes present. (Author)

  20. Glutathione in the modulation of radiosensitivity: a review

    International Nuclear Information System (INIS)

    Umadevi, P.; Prasanna, P.G.S.

    1993-01-01

    Glutathione (γ - glutamyl cysteinyl glycine, GSH) constitutes the major low molecular weight thiol compound in the mammalian cells. GSH has been assigned an important role in determining the inherent radiosensitivity of cells. Endogenous GSH involved in a number of radiation induced chemical processes, which help in the repair of radiation injury to the target molecules. Experimental evidence suggests that GSH competes with molecular oxygen in the cells to prevent fixation of DNA damage. Certain chemicals like buthionine sulfoximine are found to deplete the cellular GSH content by interactions at specific sites in the GSH cycle. It may be possible to take advantage of this phenomenon by increasing the radiosensitivity of hypoxic tumor cells, without seriously affecting the normal cells, so as to increase the therapeutic efficiency of radiation treatment. (author). 52 refs., 1 fig

  1. The radiosensitivity of nile tilapia (Oreochromis niloticus) fingerlings

    Energy Technology Data Exchange (ETDEWEB)

    Reyes, Michael Joseph T; Velasco, Pia Victoria V

    2000-04-01

    The nile tilapia (Oreochromis niloticus), a very popular fish commercially in the Philippines, was studied to determine its radiosensitivity and to see its potential as a biological indicator in aquatic ecosystems. Nile tilapia was seen to be radiosensitive. The fish were exposed to gamma-irradiation and chromosomal aberrations were induced. The various types of aberrations seen were chromatid gaps, chromosome gaps, chromatid fragments, dicentric rings, fusions, despiralizations and translocations. Among the aberrations observed, dicentric rings, fusions and chromosome gaps were strongly correlated with dosage, with only the dicentric rings increasing steadily with increasing dosage. In the course of the study, the lethal dosage{sub 50} for nile tilapia with 18 days was determined and it was observed at 2.0 krad. The modal chromosome number was also established at 2n=44 with a karyotype exhibiting 22 pairs of acrocentric chromosomes with 2 pairs of marker chromosomes present. (Author)

  2. Dosimetry using radiosensitive gels in radiotherapy: significance and methods

    International Nuclear Information System (INIS)

    Gibon, D.; Bourel, P.; Castelain, B.; Marchandise, X.; Rousseau, J.

    2001-01-01

    The goal of conformal radiotherapy is to concentrate the dose in a well-defined volume by avoiding the neighbouring healthy structures. This technique requires powerful treatment planning software and a rigorous control of estimated dosimetry. The usual dosimetric tools are not adapted to visualize and validate complex 3D treatment. Dosimetry by radiosensitive gel permits visualization and measurement of the three-dimensional dose distribution. The objective of this work is to report on current work in this field and, based on our results and our experience, to draw prospects for an optimal use of this technique. Further developments will relate to the realization of new radiosensitive gels satisfying, as well as possible, cost requirements, easy realization and use, magnetic resonance imagery (MRI) sensitivity, tissue equivalence, and stability. Other developments focus on scanning methods, especially in MRI to measure T1 and T2. (author)

  3. Electron paramagnetic resonance highlights that the oxygen effect contributes to the radiosensitizing effect of paclitaxel.

    Directory of Open Access Journals (Sweden)

    Fabienne Danhier

    Full Text Available BACKGROUND: Paclitaxel (PTX is a potent anti-cancer chemotherapeutic agent and is widely used in the treatments of solid tumors, particularly of the breast and ovaries. An effective and safe micellar formulation of PTX was used to administer higher doses of PTX than Taxol® (the current commercialized drug. We hypothesize that PTX-loaded micelles (M-PTX may enhance tumor radiosensitivity by increasing the tumor oxygenation (pO(2. Our goals were (i to evaluate the contribution of the "oxygen effect" to the radiosensitizing effect of PTX; (ii to demonstrate the therapeutic relevance of the combination of M-PTX and irradiation and (iii to investigate the underlying mechanisms of the observed oxygen effect. METHODOLOGY AND PRINCIPAL FINDINGS: We used (PEG-p-(CL-co-TMC polymeric micelles to solubilize PTX. pO(2 was measured on TLT tumor-bearing mice treated with M-PTX (80 mg/kg using electron paramagnetic resonance (EPR oximetry. The regrowth delay following 10 Gy irradiation 24 h after M-PTX treatment was measured. The tumor perfusion was assessed by the patent blue staining. The oxygen consumption rate and the apoptosis were evaluated by EPR oximetry and the TUNEL assay, respectively. EPR oximetry experiments showed that M-PTX dramatically increases the pO(2 24 h post treatment. Regrowth delay assays demonstrated a synergy between M-PTX and irradiation. M-PTX increased the tumor blood flow while cells treated with M-PTX consumed less oxygen and presented more apoptosis. CONCLUSIONS: M-PTX improved the tumor oxygenation which leads to synergy between this treatment and irradiation. This increased pO(2 can be explained both by an increased blood flow and an inhibition of O(2 consumption.

  4. Do prostaglandins affect cellular radiosensitivity in vitro

    International Nuclear Information System (INIS)

    Millar, B.C.; Jinks, S.

    1984-01-01

    The authors were unable to detect any change in the in vitro radiation response of mouse fibrosarcoma cells, HSDM 1 C 1 , which secrete 2 μg PGE 2 /mg cell protein/24 h, in the presence of the prostaglandin biosynthesis inhibitor flurbiprofen. Furthermore, addition of exogenous PGE 1 or PGA 2 to cultures of Chinese hamster cells was similarly without effect on radiation response. Although a high concentration of PGA 2 inhibited the growth of Chinese hamster cells in vitro this effect disappeared upon removal of the prostaglandin. The implications of these results for radiotherapy are discussed. (author)

  5. Do prostaglandins affect cellular radiosensitivity in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Millar, B.C.; Jinks, S. (Institute of Cancer Research, Sutton (UK). Surrey Branch)

    1984-10-01

    The authors were unable to detect any change in the in vitro radiation response of mouse fibrosarcoma cells, HSDM/sub 1/C/sub 1/, which secrete 2 ..mu..g PGE/sub 2//mg cell protein/24 h, in the presence of the prostaglandin biosynthesis inhibitor flurbiprofen. Furthermore, addition of exogenous PGE/sub 1/ or PGA/sub 2/ to cultures of Chinese hamster cells was similarly without effect on radiation response. Although a high concentration of PGA/sub 2/ inhibited the growth of Chinese hamster cells in vitro this effect disappeared upon removal of the prostaglandin. The implications of these results for radiotherapy are discussed.

  6. Radiosensitivity of the swiss-rap mouse as a function of its growth rate

    International Nuclear Information System (INIS)

    Legeay, G.; Glas, J.F.

    1969-01-01

    The results of an exhaustive study of the age dependence of the radiosensitivity of female Swiss-Rap mice are given. A close relationship of radiosensitivity versus age could not be brought out, whereas the weekly growth rate could be accurately related to radiosensitivity. Thus, the latter should be studied when a strain is to be used for biological experiments, as the rates of growth are different with the strains. (author) [fr

  7. Nicotinamide and carbogen: relationship between pO2 and radiosensitivity in three tumour lines

    International Nuclear Information System (INIS)

    Martin, L.M.; Thomas, C.D.; Guichard, M.

    1994-01-01

    The effects of carbogen breathing, nicotinamide injection and their combination on tumour radiosensitivity were correlated with changes in tumour O 2 tension to determine the relationship between radiosensitivity and measured pO 2 . The radiosensitivity (in vivo-in vitro colony assay) and O 2 tension (computerized pO 2 histograph KIMOC 6650) of two human xenografted tumours (HRT18 and NA11 +) and one murine tumour (EMT6) were measured under similar experimental conditions. (author)

  8. Differences in radiosensitivity between three HER2 overexpressing cell lines

    International Nuclear Information System (INIS)

    Steffen, Ann-Charlott; Tolmachev, Vladimir; Stenerloew, Bo; Goestring, Lovisa; Palm, Stig; Carlsson, Joergen

    2008-01-01

    HER2 is a potential target for radionuclide therapy, especially when HER2 overexpressing breast cancer cells are resistant to Herceptin registered treatment. Therefore, it is of interest to analyse whether HER2 overexpressing tumour cells have different inherent radiosensitivity. The radiosensitivity of three often used HER2 overexpressing cell lines, SKOV-3, SKBR-3 and BT-474, was analysed. The cells were exposed to conventional photon irradiation, low linear energy transfer (LET), to characterise their inherent radiosensitivity. The analysis was made with clonogenic survival and growth extrapolation assays. The cells were also exposed to alpha particles, high LET, from 211 At decays using the HER2-binding affibody molecule 211 At-(Z HER2:4 ) 2 as targeting agent. Assays for studies of internalisation of the affibody molecule were applied. SKOV-3 cells were most radioresistant, SKBR-3 cells were intermediate and BT-474 cells were most sensitive as measured with the clonogenic and growth extrapolation assays after photon irradiation. The HER2 dependent cellular uptake of 211 At was qualitatively similar for all three cell lines. However, the sensitivity to the alpha particles from 211 At differed; SKOV-3 was most resistant, SKBR-3 intermediate and BT-474 most sensitive. These differences were unexpected because it is assumed that all types of cells should have similar sensitivity to high-LET radiation. The sensitivity to alpha particle exposure correlated with internalisation of the affibody molecule and with size of the cell nucleus. There can be differences in radiosensitivity, which, if they also exist between patient breast cancer cells, are important to consider for both conventional radiotherapy and for HER2-targeted radionuclide therapy. (orig.)

  9. The progress of radiosensitive genes of human brain glioma

    International Nuclear Information System (INIS)

    Wang Xi; Liu Qiang

    2008-01-01

    Human gliomas are one of the most aggressive tumors in brain which grow infiltrativly. Surgery is the mainstay of treatment. But as the tumor could not be entirely cut off, it is easy to relapse. Radiotherapy plays an important role for patients with gliomas after surgery. The efficacy of radiotherapy is associated with radio sensitivity of human gliomas. This paper makes a summary of current situation and progress for radiosensitive genes of human brain gliomas. (authors)

  10. Cell kinetic and radiosensitivity of PHA stimulated goat lymphocytes

    International Nuclear Information System (INIS)

    Debuyst, B.; Rosenthal, M.; Leonard, A.

    1982-01-01

    The harlequin-staining method has been used to study the cell kinetic of goat peripheral blood lymphocytes stimulated by phytohemagglutinin and to assess their radiosensitivity. At 48 h, the standardized culture time employed for human lymphocytes, 71% of the goat lymphocytes are in first mitosis, 23% are in second mitosis and 5% in third. Irradiation with 200 rads X-rays induces an average of 24,5 dicentric chromosomes per hundred cells in first mitosis [fr

  11. Cell proliferation and radiosensitivity of cow lymphocytes in culture

    International Nuclear Information System (INIS)

    Modave, C.; Fabry, L.; Leonard, A.

    1982-01-01

    The harlequin-staining technique has been used to study, after PHA-stimulation, the cell proliferation of cow lymphocytes in culture and to assess the radiosensitivity in first mitosis cells. At the 48 h fixation time, only 34% of the cells are in first mitosis whereas 55% are already in second and 11% in third mitosis. The exposure of cow lymphocytes to 200 rad X-rays result in the production of 16% dicentric chromosomes in first mitosis cells [fr

  12. Radiosensitivity of yeast cells as a function of radiation LET

    International Nuclear Information System (INIS)

    Lobachevskij, P.N.; Krasavin, E.A.

    1988-01-01

    A model is proposed for interpreting the radiosensitivity of yeast cells as a function of linear energy transfer (LET) of ionizing radiation. The model takes into account the role of repair processes in sensitivity of yeast cells to ionizing radiation of different LET. Two types of repair are discussed: (1) a nonspecific repair (characteristic of both haploid and diploid cells), and (2) a diploid - soecific repair (characteristic of diploid cells only)

  13. Influence of varying diets on radiosensitivity of quinea pigs

    International Nuclear Information System (INIS)

    Darenskaya, N.G.; Kuznetsova, S.S.; Lebengarts, Ya.Z.

    1975-01-01

    Seven groups of 25-day-old Guinea pig males given different diets during the entire observation period. Six groups received full-ration granulated mixed food varying in the contents of protein and cellulose, while the seventh group ate natural food. Experiments with irradiation failed to reveal any essential differences in radiosensitivity of animals grown on natural and mixed food, which enabled us to propose full-ration granulated mixed food for feeding laboratory guinea pigs

  14. Influence of varying diets on radiosensitivity of quinea pigs

    Energy Technology Data Exchange (ETDEWEB)

    Darenskaya, N G; Kuznetsova, S S; Lebengarts, Ya Z

    1975-07-01

    Seven groups of 25-day-old Guinea pig males given different diets during the entire observation period. Six groups received full-ration granulated mixed food varying in the contents of protein and cellulose, while the seventh group ate natural food. Experiments with irradiation failed to reveal any essential differences in radiosensitivity of animals grown on natural and mixed food, which enabled us to propose full-ration granulated mixed food for feeding laboratory guinea pigs.

  15. Days on radiosensitivity: individual variability and predictive tests

    International Nuclear Information System (INIS)

    2008-01-01

    The radiosensitivity is a part of usual clinical observations. It is already included in the therapy protocols. however, some questions stay on its individual variability and on the difficulty to evaluate it. The point will be stocked on its origin and its usefulness in predictive medicine. Through examples on the use of predictive tests and ethical and legal questions that they raise, concrete cases will be presented by specialists such radio biologists, geneticists, immunologists, jurists and occupational physicians. (N.C.)

  16. Comparative study of radiosensitivity of normal and regenerating tissues

    International Nuclear Information System (INIS)

    Samokhvalova, H.S.; Popova, M.F.

    1983-01-01

    A comparative study of radiosensitivity of cells of normal and regenerating tissues of bone marrow and spleen has demonstrated that single exposure to X-rays produces a lesser damaging effect on regenerating tissues than on normal ones. The data obtained indicate that the increase in radioresistance of the organism during active regeneration of the haemopoietic organs is due not merely to the increase in the dividing cell pool of these organs but also to qualitative changes in their functional state

  17. Low-Dose Radiation Cataract and Genetic Determinants of Radiosensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Kleiman, Norman Jay [Columbia University

    2013-11-30

    The lens of the eye is one of the most radiosensitive tissues in the body. Ocular ionizing radiation exposure results in characteristic, dose related, progressive lens changes leading to cataract formation. While initial, early stages of lens opacification may not cause visual disability, the severity of such changes progressively increases with dose until vision is impaired and cataract extraction surgery may be required. Because of the transparency of the eye, radiation induced lens changes can easily be followed non-invasively over time. Thus, the lens provides a unique model system in which to study the effects of low dose ionizing radiation exposure in a complex, highly organized tissue. Despite this observation, considerable uncertainties remain surrounding the relationship between dose and risk of developing radiation cataract. For example, a growing number of human epidemiological findings suggest significant risk among various groups of occupationally and accidentally exposed individuals and confidence intervals that include zero dose. Nevertheless, questions remain concerning the relationship between lens opacities, visual disability, clinical cataract, threshold dose and/or the role of genetics in determining radiosensitivity. Experimentally, the response of the rodent eye to radiation is quite similar to that in humans and thus animal studies are well suited to examine the relationship between radiation exposure, genetic determinants of radiosensitivity and cataractogenesis. The current work has expanded our knowledge of the low-dose effects of X-irradiation or high-LET heavy ion exposure on timing and progression of radiation cataract and has provided new information on the genetic, molecular, biochemical and cell biological features which contribute to this pathology. Furthermore, findings have indicated that single and/or multiple haploinsufficiency for various genes involved in DNA repair and cell cycle checkpoint control, such as Atm, Brca1 or Rad9

  18. Inhibition of autophagy induced by TSA sensitizes colon cancer cell to radiation.

    Science.gov (United States)

    He, Gang; Wang, Yan; Pang, Xueli; Zhang, Bo

    2014-02-01

    Radiotherapy is one of the main treatments for clinical cancer therapy. However, its application was limited due to lack of radiosensitivity in some cancers. Trichostatin A (TSA) is a classic histone deacetylases inhibitor (HDACi) that specifically inhibits the biochemical functions of HDAC and is demonstrated to be an active anticancer drug. However, whether it could sensitize colon cancer to radiation is not clear. Our results showed that TSA enhanced the radiosensitivity of colon cancer cells as determined by CCK-8 and clonogenic survival assay. Moreover, apoptotic cell death induced by radiation was enhanced by TSA treatment. Additionally, TSA also induced autophagic response in colon cancer cells, while autophagy inhibition led to cell apoptosis and enhanced the radiosensitivity of colon cancer cells. Our data suggested that inhibition of cytoprotective autophagy sensitizes cancer cell to radiation, which might be further investigated for clinical cancer radiotherapy.

  19. Radiosensitization: enhancing the radiation inactivation of foodborne bacteria

    Science.gov (United States)

    Borsa, J.; Lacroix, M.; Ouattara, B.; Chiasson, F.

    2004-09-01

    Irradiation of meat products to kill pathogens can be limited by radiation-induced detriment of sensory quality. Since such detriment is directly related to dose, one approach to reduce it is by devising means to lower the dose of radiation required for processing. Increasing the radiation sensitivity of the target microorganisms would lower the dose required for a given level of microbial kill. In this work, the radiation sensitivities of inoculated Escherichia coli and Salmonella typhi in ground beef were examined under a variety of conditions. Results showed that specific manipulations of treatment conditions significantly increased the radiation sensitivity of the test organisms, ranging from a few percent to several-fold reduction in D10. In particular, radiation sensitization could be effected by certain additives, including carvacrol, thymol and trans-cinnamaldehyde, and also by certain compositions of modified atmosphere in the package headspace. A combination of additives and modified atmosphere effected a greater radiosensitization effect than could be achieved by either factor applied alone. Radiosensitization could be demonstrated with irradiation of either fresh or frozen ground meat. The radiosensitization phenomenon may be of practical utility in enhancing the technical effectiveness and feasibility of irradiation of a variety of meat and other food products.

  20. Radiosensitization of human endothelial cells by IL-24

    International Nuclear Information System (INIS)

    Meyn, R.E.

    2003-01-01

    Radiation therapy remains an important cancer treatment modality but despite improvements in dose delivery many patients still fail at their primary tumor site. Therefore, new strategies designed to improve local control are needed. Protocols combining radiation with anti-angiogenic agents might be of particular advantage based on their documented low toxicity. In this regard, we have been conducting preclinical investigations of a novel cytokine, mda7/IL-24. Our collaborators have shown that mda7/IL-24 protein targets the endothelial cells of the tumor microvascular system and has potent anti-angiogenic properties in both in vitro and in vivo assays. Recently, we have demonstrated that recombinant mda7/IL-24 protein radiosensitizes human endothelial cells in vitro. Specifically, 10 ng/ml of recombinant human IL-24 protein for 12 hrs reduced the survival at 2 Gy for human umbilical vein endothelial cells (HUVECs) from 0.33 to 0.12. We are also working on understanding the molecular basis for this radiosensitizing effect. Preliminary data suggest a model whereby mda7/IL-24 engages a specific receptor on the surface of endothelial cells and initiates a signal transduction pathway that modulates the cell's propensity for radiation-induced apoptosis and capacity for repairing radiation-induced DNA double strand breaks. Mechanistic insight gained from these studies may have implications for the actions of other anti-angiogenic agents and may generally explain the regulation of radiosensitivity imparted by growth factors and cytokines

  1. Misonidazole radiosensitization in vivo: A therapeutic gain by penicillin pretreatment

    International Nuclear Information System (INIS)

    Sheldon, P.W.; Clarke, C.; Dawson, K.B.; Simpson, W.; Simmons, D.J.C.; Adams, G.E.

    1984-01-01

    Because intestinal microflora have the potential to metabolize nitroimidazole compounds (possibly to toxic species), the authors investigated their influence on the pharmacological, neurotoxic and radiosensitizing properties of misonidazole (MIS) in mice. This was done by comparing the responses obtained in 'normal' mice to those obtained in mice whose microflora had been depleted by pretreatment for 7-14 days with penicillin (PEN) at the rate of 0.5g/1 of drinking water. Bacteriological studies showed this treatment to C57B1 mice eliminated more than 99% of the flora from the caeca and, furthermore, this efficacy of penicillin was not interfered with by MIS administered IP at 0.3mg/g between days 7-14. This pretreatment resulted not only in the elimination of the caecal flora, but also in an increase in the pharmacokinetic exposure to MIS, an increase in Lewis lung tumour radiosensitization by MIS and a decrease in MIS-induced neurotoxicity. The authors conclude pretreatment with PEN can give a therapeutic gain with MIS radiosensitization. Further, assuming no direct interaction between the PEN and MIS, these findings indicate that the intestinal flora may produce neurotoxic species by their metabolism of MIS

  2. Radiosensitization: enhancing the radiation inactivation of foodborne bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Borsa, J. E-mail: jborsa@mds.nordion.com; Lacroix, M.; Ouattara, B.; Chiasson, F

    2004-10-01

    Irradiation of meat products to kill pathogens can be limited by radiation-induced detriment of sensory quality. Since such detriment is directly related to dose, one approach to reduce it is by devising means to lower the dose of radiation required for processing. Increasing the radiation sensitivity of the target microorganisms would lower the dose required for a given level of microbial kill. In this work, the radiation sensitivities of inoculated Escherichia coli and Salmonella typhi in ground beef were examined under a variety of conditions. Results showed that specific manipulations of treatment conditions significantly increased the radiation sensitivity of the test organisms, ranging from a few percent to several-fold reduction in D{sub 10}. In particular, radiation sensitization could be effected by certain additives, including carvacrol, thymol and trans-cinnamaldehyde, and also by certain compositions of modified atmosphere in the package headspace. A combination of additives and modified atmosphere effected a greater radiosensitization effect than could be achieved by either factor applied alone. Radiosensitization could be demonstrated with irradiation of either fresh or frozen ground meat. The radiosensitization phenomenon may be of practical utility in enhancing the technical effectiveness and feasibility of irradiation of a variety of meat and other food products.

  3. Interspecies variations inchromosomal radiosensitivity and repair among mammals

    International Nuclear Information System (INIS)

    Leonard, A.

    1988-01-01

    A review is presented of studies comparing relative chromosomal radiosensitivity of different mammalian species with the objective of assessing the induction of chromosomal aberrations in somatic cells following acute irradiation, the in vivo survival of peripheral blood lymphocytes carrying chromosomal abberations, and the correlation between chromosomal radiosensitivity of peripheral blood lymphocytes and of male germ cells. The ultimate aim was to find whether animal cell experiments can be used to replace experiments in man. The studies showed that the differences in radiosensitivity of the peripheral blood lymphocytes in the most commonly used animals and in man are insignificant and the results in animals are qualitatively and quantitatively representative of what can be expected for man. The life of peripheral blood lymphocytes carrying chromosomal abberations, however, is very short in most experimental animals. The animals thus cannot be used in studies of chromosome damage resulting from chronic irradiation. The studies also show that the yields of dicentric chromosomes in peripheral blood lymphocytes and of reciprocal translocations induced in germ cells are characteristic of each species and animal experiments cannot replace direct studies in man in this respect. (L.O.). 3 tabs., 40 refs

  4. Formation of radical anions of radiosensitizers and related model compounds via electrospray ionization

    DEFF Research Database (Denmark)

    Feketeová, Linda; Albright, Abigail L; Sørensen, Brita Singers

    2014-01-01

    Radiosensitizers are used in radiotherapy to enhance tumour control of radioresistant hypoxic tumours. While the detailed mechanism of radiosensitization is still unknown, the formation of radical anions is believed to be a key step. Thus understanding the ionization reactions of radiosensitizers......, misonidazole and related compounds using a hybrid linear ion trap – Fourier Transform Ion Cyclotron Resonance mass spectrometer (Finnigan-LTQ-FT). A key finding is that negative electrospray ionization of these radiosensitizers leads to the formation of radical anions, allowing their fragmentation reactions...

  5. Expression of p210 BCR/ABl increases hematopoietic progenitor cell radiosensitivity

    International Nuclear Information System (INIS)

    Santucci, M.A.; Anklesaria, P.; Das, I.J.; Sakakeeny, M.A.; FitzGerald, T.J.; Greenberger, J.S.; Laneuville, P.

    1993-01-01

    The cytogenetic finding of the Ph1+ chromosome and its molecular biologic marker bcr/abl gene rearrangement in cells from patients with chronic myeloid leukemia are associated with a proliferative advantage of the Ph1+ clone in vivo. Although the transition to the acute terminal phase or blastic crisis is often associated with additional cytogenetic abnormalities, the molecular events which correlate the initial cytogenetic lesion with the terminal phase are poorly understood. Defective cellular DNA repair capacity is often associated with chromosomal instability, increased mutation frequency, and biologic alterations. The authors tested whether the protein product of the bcr/abl translocation (p210) could alter DNA repair after gamma-irradiation of murine cell lines expressing the bcr/abl cDNA. The 32D cl 3 parent, 32D cl 3 pYN (containing the control vector plasmid) and each of two sources of 32D cl 3 cells expressing p210 cDNA (32D-PC1 cell line and 32D-LG7 subclone) showed a D 0 of 1.62, 1.57, 1.16, and 1.27 Gy, respectively. Thus, expression of the p210 product induced a significant increase in radiosensitivity at the clinically relevant radiation therapy dose-rate. The increased radiosensitivity of p210-expressing cells persisted if cells were held before plating in a density-inhibited state for 8 hr after gamma-irradiation, indicating little effect on the repair of potentially lethal gamma-irradiation damage. The IL-3 dependent parent 32D cl 3 cells demonstrated programmed cell death in the absence of growth factor or following gamma-irradiation to 200 cGy. Expression of p210 cDNA in the 32D-PC1 and 32D-LG7 subclones abrogated IL-3 requirement of these cell lines and inhibited gamma-irradiation induced programmed cell death. These data suggest a role for p210 in amplifying gamma-irradiation DNA damage or broadly inhibiting DNA repair, conditions that may stimulate further cytogenetic alterations in hematopoietic cells. 43 refs., 3 figs., 1 tab

  6. Radiosensitizing effect of nitric oxide in tumor cells and experimental tumors irradiated with gamma rays and proton beams

    International Nuclear Information System (INIS)

    Policastro, Lucia L.; Duran, Hebe; Molinari, Beatriz L.; Somacal, Hector R.; Valda, Alejandro A.

    2003-01-01

    Nitric oxide (NO) has been reported to be a radiosensitizer of mammalian cells under hypoxic conditions. In a previous study, we demonstrated an enhancement in radiation response induced by NO in mouse tumor cells under aerobic conditions, with an increasing effect as a function of malignancy. The aim of the present study was to evaluate the effect of NO in tumor cells and in experimental tumors irradiated with γ rays and proton beams. Irradiations were performed with a 137 Cs γ source and with proton beams generated by the TANDAR accelerator. Tumor cells were treated with the NO donor DETA-NO and the sensitizer enhancement ratio (SER) was calculated using the α parameter of the survival curve fitted to the linear-quadratic model. Tumor cells irradiated with protons were radio sensitized by DETA-NO only in the more malignant cells irradiated with low LET protons (2.69±0.08 keV/μm). For higher LET protons there were no radiosensitizing effect. For human tumor cells pre-treated with DETA-NO and irradiated with γ rays, a significantly greater effect was demonstrated in the malignant cells (MCF-7) as compared with the near normal cells (HBL-100). Moreover, a significant decrease in tumor growth was demonstrated in mice pre-treated with the NO donor spermine and irradiated with γ rays and low LET protons as compared with mice irradiated without pre-treatment with the NO donor. In conclusion, we demonstrated a differential effect of NO as a radiosensitizer of malignant cells, both with γ rays and low LET protons. This selectivity, coupled to the in vivo inhibition of tumor growth, is of great interest for the potential use of NO releasing agents in radiotherapy. (author)

  7. Cloning of smac gene and its overexpression effects on radiosensitivity of HeLa cells to γ-rays

    International Nuclear Information System (INIS)

    Zhao Baofeng; Tian Mei; Lei Hongwei; Su Xu

    2006-01-01

    Objective: To clone smac gene and construct eukaryocytic expression vector pcDNA3.1/ smac. The smac gene was transfected into HeLa cells to explore the effects of over-expression of extrinsic smac gene on radiosensitivity to γ-rays of HeLa cells. Methods: The full-length smac gene was amplified from total RNA of HeLa cells by RTPCR. The RTPCR product was ligated with the vector pcDNA3.1 and sequenced. The correct pcDNA3.1/smac was transfected into HeLa cells. The expression of smac gene was tested by RTPCR and Western blot. The cellular growth inhibition rates were evaluated by MTT 48 horns after irradiation with different doses of γ-rays. Results: Recombinant eukaryocytic expression vector pcDNA3.1/smac was successfully constructed. RTPCR and Western blot results indicated that the expression of smac gene of HeLa/smac cells was significantly enhanced compared with the expression of smac gene of HeLa/pcDNA3.1 and HeLa cells. 48 hours after different doses of γ-ray irradiation was significantly higher in pcDNA3.1/smac transfected HeLa/smac cells than those of non-transfected HeLa cells or pcDNA3.1 transfected HeLa/pcDNA3.1 cells, inhabitation rates were 38.85%, 17.64% and 20.32%, respectively. Conclusions: smac gene was successfully cloned. Extrinsic smac gene over-expression could significantly enhance radiosensitivity to γ-ray of HeLa cells, which would herald a new approach to improve radiosensitivity of cervical cancer. (authors)

  8. Regional differences in radiosensitivity across the rat cervical spinal cord

    International Nuclear Information System (INIS)

    Bijl, Hendrik P.; Luijk, Peter van; Coppes, Rob P.; Schippers, Jacobus M.; Konings, Antonius W.T.; Kogel, Albert J. van der

    2005-01-01

    Purpose: To study regional differences in radiosensitivity within the rat cervical spinal cord. Methods and materials: Three types of inhomogeneous dose distributions were applied to compare the radiosensitivity of the lateral and central parts of the rat cervical spinal cord. The left lateral half of the spinal cord was irradiated with two grazing proton beams, each with a different penumbra (20-80% isodoses): lateral wide (penumbra = 1.1 mm) and lateral tight (penumbra = 0.8 mm). In the third experiment, the midline of the cord was irradiated with a narrow proton beam with a penumbra of 0.8 mm. The irradiated spinal cord length (CT-2) was 20 mm in all experiments. The animals were irradiated with variable single doses of unmodulated protons (150 MeV) with the shoot-through method, whereby the plateau of the depth-dose profile is used rather than the Bragg peak. The endpoint for estimating isoeffective dose (ED 50 ) values was paralysis of fore and/or hind limbs within 210 days after irradiation. Histology of the spinal cords was performed to assess the radiation-induced tissue damage. Results: High-precision proton irradiation of the lateral or the central part of the spinal cord resulted in a shift of dose-response curves to higher dose values compared with the homogeneously irradiated cervical cord to the same 20-mm length. The ED 50 values were 28.9 Gy and 33.4 Gy for the lateral wide and lateral tight irradiations, respectively, and as high as 71.9 Gy for the central beam experiment, compared with 20.4 Gy for the homogeneously irradiated 20-mm length of cervical cord. Histologic analysis of the spinal cords showed that the paralysis was due to white matter necrosis. The radiosensitivity was inhomogeneously distributed across the spinal cord, with a much more radioresistant central white matter (ED 50 = 71.9 Gy) compared with lateral white matter (ED 50 values = 28.9 Gy and 33.4 Gy). The gray matter did not show any noticeable lesions, such as necrosis or

  9. Biological markers as predictors of radiosensitivity in syngeneic murine tumors

    International Nuclear Information System (INIS)

    Chang, Sei Kyung; Shin, Hyun Soo; Seong, Jin Sil; Kim, Sung Hee

    2006-01-01

    We investigated whether a relationship exists between tumor control dose 50 (TCD 50 ) or tumor growth delay (TGD) and radiation induced apoptosis (RIA) in syngeneic murine tumors. Also we investigated the biological markers that can predict radiosensitivity in murine tumor system through analysis of relationship between TCD 50 , TGD, RIA and constitutive expression levels of the genetic products regulating RIA. Syngeneic murine tumors such as ovarian adenocarcinoma, mammary carcinoma, squamous cell carcinoma, fibrosarcoma, hepatocarcinoma were used in this study. C3H/HeJ mice were bred and maintained in our specific pathogen free mouse colony and were 8 ∼ 12 weeks old when used for the experiments. The tumors, growing in the right hind legs of mice, were analyzed for TCD 50 , TGD, and RIA at 8 mm in diameter. The tumors were also analyzed for the constitutive expression levels of p53, p21 WAF1/CIP1 , BAX, Bcl-2, Bcl-x L , Bcl-x S , and p34. Correlation analysis was performed whether the level of RIA were correlated with TCD 50 or TGD, and the constitutive expression levels of genetic products regulating RIA were correlated with TCD 50 , TGD, RIA. The level of RIA showed a significant positive correlation (R = 0.922, ρ = 0.026) with TGD, and showed a trend to correlation (R = -0.848), marginally significant correlation with TCD 50 (ρ = 0.070). It indicates that tumors that respond to radiation with high percentage of apoptosis were more radiosensitive. The constitutive expression levels of p21 WAF1/CIP1 and p34 showed a significant correlation either with TCD 50 (R = 0.893, ρ = 0.041 and R = 0.904, ρ = 0.035) or with TGD (R = -0.922, ρ 0.026 and R = -0.890, ρ = 0.043). The tumors with high constitutive expression levels of p21 WAF1/CIP1 or p34 were less radiosensitive than those with low expression. Radiosensitivity may be predicted with the level of RIA in murine tumors. The constitutive expression levels of p21 WAF1/CIP1 or p34 can be used as biological

  10. Preferential radiosensitization of human prostatic carcinoma cells by mild hyperthermia

    International Nuclear Information System (INIS)

    Ryu, Samuel; Brown, Stephen L.; Kim, Sang-Hie; Khil, Mark S.; Kim, Jae Ho

    1996-01-01

    Purpose: Recent cell culture studies by us and others suggest that some human carcinoma cells are more sensitive to heat than are rodent cells following mild hyperthermia. In studying the cellular mechanism of enhanced thermosensitivity of human tumor cells to hyperthermia, prostatic carcinoma cells of human origin were found to be more sensitive to mild hyperthermia than other human cancer cells. The present study was designed to determine the magnitude of radiosensitization of human prostatic carcinoma cells by mild hyperthermia and to examine whether the thermal radiosensitization is related to the intrinsic thermosensitivity of cancer cells. Methods and Materials: Two human prostatic carcinoma cell lines (DU-145 and PC-3) and other carcinoma cells of human origin, in particular, colon (HT-29), breast (MCF-7), lung (A-549), and brain (U-251) were exposed to temperatures of 40-41 deg. C. Single acute dose rate radiation and fractionated radiation were combined with mild hyperthermia to determine thermal radiosensitization. The end point of the study was the colony-forming ability of single-plated cells. Results: DU-145 and PC-3 cells were found to be exceedingly thermosensitive to 41 deg. C for 24 h, relative to other cancer cell lines. Ninety percent of the prostatic cancer cells were killed by a 24 h heat exposure. Prostatic carcinoma cells exposed to a short duration of heating at 41 deg. C for 2 h resulted in a substantial enhancement of radiation-induced cytotoxicity. The thermal enhancement ratios (TERs) of single acute dose radiation following heat treatment 41 deg. C for 2 h were 2.0 in DU-145 cells and 1.4 in PC-3 cells. The TERs of fractionated irradiation combined with continuous heating at 40 deg. C were similarly in the range of 2.1 to 1.4 in prostate carcinoma cells. No significant radiosensitization was observed in MCF-7 and HT-29 cells under the same conditions. Conclusion: The present data suggest that a significant radiosensitization of

  11. Biological markers as predictors of radiosensitivity in syngeneic murine tumors

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Sei Kyung; Shin, Hyun Soo [Bundang CHA General Hospital, Seongnam (Korea, Republic of); Seong, Jin Sil; Kim, Sung Hee [Yonsei Cancer Center, Yonsei University College of Medicine, Seoul (Korea, Republic of)

    2006-06-15

    We investigated whether a relationship exists between tumor control dose 50 (TCD{sub 50}) or tumor growth delay (TGD) and radiation induced apoptosis (RIA) in syngeneic murine tumors. Also we investigated the biological markers that can predict radiosensitivity in murine tumor system through analysis of relationship between TCD{sub 50}, TGD, RIA and constitutive expression levels of the genetic products regulating RIA. Syngeneic murine tumors such as ovarian adenocarcinoma, mammary carcinoma, squamous cell carcinoma, fibrosarcoma, hepatocarcinoma were used in this study. C3H/HeJ mice were bred and maintained in our specific pathogen free mouse colony and were 8 {approx} 12 weeks old when used for the experiments. The tumors, growing in the right hind legs of mice, were analyzed for TCD{sub 50}, TGD, and RIA at 8 mm in diameter. The tumors were also analyzed for the constitutive expression levels of p53, p21{sup WAF1/CIP1}, BAX, Bcl-2, Bcl-x{sub L}, Bcl-x{sub S}, and p34. Correlation analysis was performed whether the level of RIA were correlated with TCD{sub 50} or TGD, and the constitutive expression levels of genetic products regulating RIA were correlated with TCD{sub 50}, TGD, RIA. The level of RIA showed a significant positive correlation (R = 0.922, {rho} = 0.026) with TGD, and showed a trend to correlation (R = -0.848), marginally significant correlation with TCD{sub 50} ({rho} = 0.070). It indicates that tumors that respond to radiation with high percentage of apoptosis were more radiosensitive. The constitutive expression levels of p21{sup WAF1/CIP1} and p34 showed a significant correlation either with TCD{sub 50} (R = 0.893, {rho} = 0.041 and R = 0.904, {rho} = 0.035) or with TGD (R = -0.922, {rho} 0.026 and R = -0.890, {rho} = 0.043). The tumors with high constitutive expression levels of p21{sup WAF1/CIP1} or p34 were less radiosensitive than those with low expression. Radiosensitivity may be predicted with the level of RIA in murine tumors. The

  12. Isoliquiritigenin induces growth inhibition and apoptosis through downregulating arachidonic acid metabolic network and the deactivation of PI3K/Akt in human breast cancer

    International Nuclear Information System (INIS)

    Li, Ying; Zhao, Haixia; Wang, Yuzhong; Zheng, Hao; Yu, Wei; Chai, Hongyan; Zhang, Jing; Falck, John R.; Guo, Austin M.; Yue, Jiang; Peng, Renxiu; Yang, Jing

    2013-01-01

    Arachidonic acid (AA)-derived eicosanoids and its downstream pathways have been demonstrated to play crucial roles in growth control of breast cancer. Here, we demonstrate that isoliquiritigenin, a flavonoid phytoestrogen from licorice, induces growth inhibition and apoptosis through downregulating multiple key enzymes in AA metabolic network and the deactivation of PI3K/Akt in human breast cancer. Isoliquiritigenin diminished cell viability, 5-bromo-2′-deoxyuridine (BrdU) incorporation, and clonogenic ability in both MCF-7 and MDA-MB-231cells, and induced apoptosis as evidenced by an analysis of cytoplasmic histone-associated DNA fragmentation, flow cytometry and hoechst staining. Furthermore, isoliquiritigenin inhibited mRNA expression of multiple forms of AA-metabolizing enzymes, including phospholipase A2 (PLA2), cyclooxygenases (COX)-2 and cytochrome P450 (CYP) 4A, and decreased secretion of their products, including prostaglandin E 2 (PGE 2 ) and 20-hydroxyeicosatetraenoic acid (20-HETE), without affecting COX-1, 5-lipoxygenase (5-LOX), 5-lipoxygenase activating protein (FLAP), and leukotriene B 4 (LTB 4 ). In addition, it downregulated the levels of phospho-PI3K, phospho-PDK (Ser 241 ), phospho-Akt (Thr 308 ), phospho-Bad (Ser 136 ), and Bcl-x L expression, thereby activating caspase cascades and eventually cleaving poly(ADP-ribose) polymerase (PARP). Conversely, the addition of exogenous eicosanoids, including PGE 2 , LTB 4 and a 20-HETE analog (WIT003), and caspase inhibitors, or overexpression of constitutively active Akt reversed isoliquiritigenin-induced apoptosis. Notably, isoliquiritigenin induced growth inhibition and apoptosis of MDA-MB-231 human breast cancer xenografts in nude mice, together with decreased intratumoral levels of eicosanoids and phospho-Akt (Thr 308 ). Collectively, these data suggest that isoliquiritigenin induces growth inhibition and apoptosis through downregulating AA metabolic network and the deactivation of PI3K/Akt in

  13. Ectopic Expression of α6 and δ GABAA Receptor Subunits in Hilar Somatostatin Neurons Increases Tonic Inhibition and Alters Network Activity in the Dentate Gyrus

    Science.gov (United States)

    Tong, Xiaoping; Peng, Zechun; Zhang, Nianhui; Cetina, Yliana; Huang, Christine S.; Wallner, Martin; Otis, Thomas S.

    2015-01-01

    The role of GABAA receptor (GABAAR)-mediated tonic inhibition in interneurons remains unclear and may vary among subgroups. Somatostatin (SOM) interneurons in the hilus of the dentate gyrus show negligible expression of nonsynaptic GABAAR subunits and very low tonic inhibition. To determine the effects of ectopic expression of tonic GABAAR subtypes in these neurons, Cre-dependent viral vectors were used to express GFP-tagged GABAAR subunits (α6 and δ) selectively in hilar SOM neurons in SOM-Cre mice. In single-transfected animals, immunohistochemistry demonstrated strong expression of either the α6 or δ subunit; in cotransfected animals, both subunits were consistently expressed in the same neurons. Electrophysiology revealed a robust increase of tonic current, with progressively larger increases following transfection of δ, α6, and α6/δ subunits, respectively, indicating formation of functional receptors in all conditions and likely coassembly of the subunits in the same receptor following cotransfection. An in vitro model of repetitive bursting was used to determine the effects of increased tonic inhibition in hilar SOM interneurons on circuit activity in the dentate gyrus. Upon cotransfection, the frequency of GABAAR-mediated bursting in granule cells was reduced, consistent with a reduction in synchronous firing among hilar SOM interneurons. Moreover, in vivo studies of Fos expression demonstrated reduced activation of α6/δ-cotransfected neurons following acute seizure induction by pentylenetetrazole. The findings demonstrate that increasing tonic inhibition in hilar SOM interneurons can alter dentate gyrus circuit activity during strong stimulation and suggest that tonic inhibition of interneurons could play a role in regulating excessive synchrony within the network. SIGNIFICANCE STATEMENT In contrast to many hippocampal interneurons, somatostatin (SOM) neurons in the hilus of the dentate gyrus have very low levels of nonsynaptic GABAARs and exhibit

  14. Biophysical Network Modelling of the dLGN Circuit: Different Effects of Triadic and Axonal Inhibition on Visual Responses of Relay Cells.

    Directory of Open Access Journals (Sweden)

    Thomas Heiberg

    2016-05-01

    Full Text Available Despite its prominent placement between the retina and primary visual cortex in the early visual pathway, the role of the dorsal lateral geniculate nucleus (dLGN in molding and regulating the visual signals entering the brain is still poorly understood. A striking feature of the dLGN circuit is that relay cells (RCs and interneurons (INs form so-called triadic synapses, where an IN dendritic terminal can be simultaneously postsynaptic to a retinal ganglion cell (GC input and presynaptic to an RC dendrite, allowing for so-called triadic inhibition. Taking advantage of a recently developed biophysically detailed multicompartmental model for an IN, we here investigate putative effects of these different inhibitory actions of INs, i.e., triadic inhibition and standard axonal inhibition, on the response properties of RCs. We compute and investigate so-called area-response curves, that is, trial-averaged visual spike responses vs. spot size, for circular flashing spots in a network of RCs and INs. The model parameters are grossly tuned to give results in qualitative accordance with previous in vivo data of responses to such stimuli for cat GCs and RCs. We particularly investigate how the model ingredients affect salient response properties such as the receptive-field center size of RCs and INs, maximal responses and center-surround antagonisms. For example, while triadic inhibition not involving firing of IN action potentials was found to provide only a non-linear gain control of the conversion of input spikes to output spikes by RCs, axonal inhibition was in contrast found to substantially affect the receptive-field center size: the larger the inhibition, the more the RC center size shrinks compared to the GC providing the feedforward excitation. Thus, a possible role of the different inhibitory actions from INs to RCs in the dLGN circuit is to provide separate mechanisms for overall gain control (direct triadic inhibition and regulation of spatial

  15. Biophysical Network Modelling of the dLGN Circuit: Different Effects of Triadic and Axonal Inhibition on Visual Responses of Relay Cells.

    Science.gov (United States)

    Heiberg, Thomas; Hagen, Espen; Halnes, Geir; Einevoll, Gaute T

    2016-05-01

    Despite its prominent placement between the retina and primary visual cortex in the early visual pathway, the role of the dorsal lateral geniculate nucleus (dLGN) in molding and regulating the visual signals entering the brain is still poorly understood. A striking feature of the dLGN circuit is that relay cells (RCs) and interneurons (INs) form so-called triadic synapses, where an IN dendritic terminal can be simultaneously postsynaptic to a retinal ganglion cell (GC) input and presynaptic to an RC dendrite, allowing for so-called triadic inhibition. Taking advantage of a recently developed biophysically detailed multicompartmental model for an IN, we here investigate putative effects of these different inhibitory actions of INs, i.e., triadic inhibition and standard axonal inhibition, on the response properties of RCs. We compute and investigate so-called area-response curves, that is, trial-averaged visual spike responses vs. spot size, for circular flashing spots in a network of RCs and INs. The model parameters are grossly tuned to give results in qualitative accordance with previous in vivo data of responses to such stimuli for cat GCs and RCs. We particularly investigate how the model ingredients affect salient response properties such as the receptive-field center size of RCs and INs, maximal responses and center-surround antagonisms. For example, while triadic inhibition not involving firing of IN action potentials was found to provide only a non-linear gain control of the conversion of input spikes to output spikes by RCs, axonal inhibition was in contrast found to substantially affect the receptive-field center size: the larger the inhibition, the more the RC center size shrinks compared to the GC providing the feedforward excitation. Thus, a possible role of the different inhibitory actions from INs to RCs in the dLGN circuit is to provide separate mechanisms for overall gain control (direct triadic inhibition) and regulation of spatial resolution

  16. Cell killing and radiosensitization by caffeic acid phenethyl ester (CAPE) in lung cancer cells

    International Nuclear Information System (INIS)

    Chen, Miao-Fen; Chen, Wen-Cheng; Wu, Chun-Te; King, P.C.

    2004-01-01

    Caffeic acid phenethyl ester (CAPE) is a biologically active ingredient of honeybee propoplis. The cytotoxicity and radiation sensitization effects of CAPE were evaluated in human lung cancer A549 cells and normal lung fibroblast WI-38 cells. A549 cells treated with 6 μg/ml CAPE showed marked growth inhibition (60%) at 48 hr after treatments. During the same time, the number of viable cells decreased to 46% of the control value. In contrast, WI-38 cells showed 20% growth inhibition with no change in the number of viable cells under the same treatment conditions. At 72 hr after CAPE treatment (6 μg/ml), the percentage of apoptotic cells in A549 cultures increased significantly to 67% and an S/G2 arrest was also detected in the culture. Furthermore, there was a significant decrease in the level of intracellular glutathione and hydrogen peroxide contents within one hr after CAPE treatment, and the expression of cyclin B 1 was reduced 6 hr after treatment. The radiation sensitization effect of CAPE on A549 cells was determined from the clonogenic survival curves, and the results showed a small but significant difference in radiation survival between cells treated with or without CAPE. Taken together, our results suggest that the effects of CAPE on differential cytotoxicity, apoptosis, and radiosensitization are associated with glutathione depletion that occurred shortly after treatments. (author)

  17. Caffeine inhibits homology-directed repair of I-SceI-induced DNA double-strand breaks.

    Science.gov (United States)

    Wang, Huichen; Boecker, Wilfried; Wang, Hongyan; Wang, Xiang; Guan, Jun; Thompson, Larry H; Nickoloff, Jac A; Iliakis, George

    2004-01-22

    We recently reported that two Chinese hamster mutants deficient in the RAD51 paralogs XRCC2 and XRCC3 show reduced radiosensitization after treatment with caffeine, thus implicating homology-directed repair (HDR) of DNA double-strand breaks (DSBs) in the mechanism of caffeine radiosensitization. Here, we investigate directly the effect of caffeine on HDR initiated by DSBs induced by a rare cutting endonuclease (I-SceI) into one of two direct DNA repeats. The results demonstrate a strong inhibition by caffeine of HDR in wild-type cells, and a substantial reduction of this effect in HDR-deficient XRCC3 mutant cells. Inhibition of HDR and cell radiosensitization to killing shows similar dependence on caffeine concentration suggesting a cause-effect relationship between these effects. UCN-01, a kinase inhibitor that effectively abrogates checkpoint activation in irradiated cells, has only a small effect on HDR, indicating that similar to radiosensitization, inhibition of checkpoint signaling is not sufficient for HDR inhibition. Recombination events occurring during treatment with caffeine are characterized by rearrangements reminiscent to those previously reported for the XRCC3 mutant, and immunofluorescence microscopy demonstrates significantly reduced formation of IR-specific RAD51 foci after caffeine treatment. In summary, our results identify inhibition of HDR as a significant contributor to caffeine radiosensitization.

  18. Genetic factors affecting radiosensitivity and cancer predisposition: application of a continuous low dose-rate irradiation colony formation assay to select radiosensitive retinoblastoma family members for correction with a cDNA library

    International Nuclear Information System (INIS)

    Wilson, P.F.; Nagasawa, H.; Bedford, J.S.; Little, J.B.

    2003-01-01

    Full text: The aim of this study is to identify new or undescribed functions of radiosensitivity and genomic instability genes using a continuous low dose-rate colony formation assay. This assay expands on the standard colony formation assay, whereby colony formation ability (retention of proliferative capacity) is measured during continuous low dose-rate irradiation rather than 10-14 days following the completion of such exposures. This approach has previously employed by the Bedford laboratory to identify a Prkdc (DNA-PKcs) mutant of CHO cells, irs-20. In this study we examine the growth response of fibroblasts derived from recently identified radiosensitive retinoblastoma family members, both affected probands and their unaffected parents, and various apparently normal fibroblast lines obtained from the NIGMS Human Genetic Cell Repository (Coriell Medical Institute, Camden, NJ). Colony formation was assayed by plating single cells, exposing them at 37 deg C to continuous Cs-137 gamma irradiation at dose rates of 0.5-8.5 cGy/h, and scoring survivors as colonies with >100 viable cells. The retinoblastoma family members display severely limited growth (survival less than 10E-3) at dose rates greater than 2-2.5 cGy/h, while the apparently normal cell lines do not display such inhibited growth until 6-7 cGy/h. Two of the retinoblastoma family cell lines, MF-6F and MF-15F (both unaffected but radiosensitive parents), were selected as targets of transfection with a viral cDNA library (ViraPort human cDNA library, Stratagene Cloning Systems, La Jolla, CA) and subjected to a ∼3 cGy/h selection dose rate, where uncorrected survival relative to normal cells is lower by a factor of 50-150. Colonies recovered will provide valuable information regarding the genetic nature of their radiosensitivity (possibly involving chromosome stability, DNA repair, and/or cell cycle regulatory pathways), that may influence risks for cancer and heritable effects for a previously

  19. BMI-1 suppression increases the radiosensitivity of oesophageal carcinoma via the PI3K/Akt signaling pathway.

    Science.gov (United States)

    Yang, Xing-Xiao; Ma, Ming; Sang, Mei-Xiang; Zhang, Xue-Yuan; Liu, Zhi-Kun; Song, Heng; Zhu, Shu-Chai

    2018-02-01

    BMI-1 knockdown, while the kinase agonist IGF-1 reversed the effects of BMI-1 knockdown on cell viability and radiosensitivity. Taken together, BMI-1 knockdown induces radiosensitivity in ESCC and significantly inhibits cell viability, which may contribute to an increased proportion of cells in the G0/G1 phase and cell apoptosis via suppression of the PI3K/Akt signalling pathway.

  20. Autophagy influences the low-dose hyper-radiosensitivity of human lung adenocarcinoma cells by regulating MLH1.

    Science.gov (United States)

    Wang, Qiong; Xiao, Zhuya; Lin, Zhenyu; Zhou, Jie; Chen, Weihong; Jie, Wuyun; Cao, Xing; Yin, Zhongyuan; Cheng, Jing

    2017-06-01

    To investigate the impact of autophagy on the low-dose hyper-radiosensitivity (HRS) of human lung adenocarcinoma cells via MLH1 regulation. Immunofluorescent staining, Western blotting, and electron microscopy were utilized to detect autophagy in A549 and H460 cells. shRNA was used to silence MLH1 expression. The levels of MLH1, mTOR, p-mTOR, BNIP3, and Beclin-1 were measured by real-time polymerase chain reaction (PCR) and Western blotting. A549 cells, which have low levels of MLH1 expression, displayed HRS/induced radioresistance (IRR). Conversely, the radiosensitivity of H460 cells, which express high levels of MLH1, conformed to the linear-quadratic (LQ) model. After down-regulating MLH1 expression, A549 cells showed increased HRS and inhibition of autophagy, whereas H460 cells exhibited HRS/IRR. The levels of mTOR, p-mTOR, and BNIP3 were reduced in cells harboring MLH1 shRNA, and the changes in the mTOR/p-mTOR ratio mirrored those in MLH1 expression. Low MLH1-expressing A549 cells may exhibit HRS. Both the mTOR/p-mTOR and BNIP3/Beclin-1 signaling pathways were found to be related to HRS, but only mTOR/p-mTOR is involved in the regulation of HRS via MLH1 and autophagy.

  1. Ginsenoside Rg3 enhances radiosensitization of hypoxic oesophageal cancer cell lines through vascular endothelial growth factor and hypoxia inducible factor 1α.

    Science.gov (United States)

    Ge, Xiaolin; Zhen, Fuxi; Yang, Baixia; Yang, Xi; Cai, Jing; Zhang, Chi; Zhang, Sheng; Cao, Yuandong; Ma, Jianxin; Cheng, Hongyan; Sun, Xinchen

    2014-06-01

    To determine if the pretreatment of hypoxic human oesophageal carcinoma cell lines (EC109, TE1 and KYSE170) with ginsenoside Rg3 (Rg3) increases their radiosensitivity to X-rays. The growth inhibitory effect of different Rg3 concentrations was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay. Radiation sensitivity was measured using a clone formation assay and flow cytometry was used to measure the effects of Rg3 on radiation-induced apoptosis. Western blot analysis was used to measure the effects of Rg3 on the levels of hypoxia inducible factor (HIF)-1α and vascular endothelial growth factor (VEGF). Rg3 inhibited EC109, TE1 and KYSE170 cell growth in a dose- and time-dependent manner. Pretreatment with 10 µmol/ml Rg3 increased EC109, TE1 and KYSE170 radiosensitivity. Rg3 plus radiation significantly increased the apoptosis rate compared with radiation alone. Rg3 also decreased VEGF and HIF-1α protein levels in EC109 cells in a dose-dependent manner. The combination of Rg3 and radiation increased the fragmentation of double-stranded DNA. Rg3 enhanced the radiosensitivity of human oesophageal carcinoma cell lines cultured under hypoxic conditions possibly by downregulating VEGF and HIF-1α protein levels. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  2. Re-evaluation of in vitro radiosensitivity of human fibroblasts of different genetic origins

    Energy Technology Data Exchange (ETDEWEB)

    Deschavanne, P.J.; Debieu, D.; Malaise, E.P.; Fertil, B.

    1986-08-01

    Statistical analysis of the radiosensitivity of 204 survival curves of non-transformed human fibroblast cell strains of different genetic origins was made using the multi-target one-hit model (characterized by parameters eta and D/sub 0/), the surviving fraction for a 2 Gy dose (S/sub 2/) and the mean inactivation dose (D-bar). D-bar is found to be the parameter for characterization of anomalous radiosensitivity linked to a genetic disorder and discrimination between groups of cell strains of differing radiosensitivity. It allows the description of a range of 'normal' radiosensitivity for control fibroblasts and classification of genetic disorders as a function of their mean radiosensitivity expressed in terms of D-bar. Nine groups of cell strains appear to exhibit radiosensitivity differing significantly from the controls: seven groups are hypersensitive (ataxia-telengiectasia homozygotes and heterozygotes, Cockayne's syndrome, Gardner's syndrome, 5-oxoprolinuria homozygotes and heterozygotes, Fanconi's anaemia) and two groups are more radioresistant (fibroblasts from retinoblastoma patients and individuals with chromosome 13 anomalies). Since the coupled parameter eta and D/sub 0/ failed to discriminate between the radiosensitivity of the different genetic groups, the use of D-bar to make an intercomparison of intrinsic radiosensitivity of non-transformed human fibroblasts is recommended. (U.K.).

  3. A study on the toxicity of three radiosensitizers on retinoblastoma cells by MTT assay

    International Nuclear Information System (INIS)

    Yi Xianjin; Jin Yizun; Ding Li; Ni Zhou; Wang Wenji

    1994-01-01

    The toxicity of three radiosensitizers BSO, CM and RSU-1069 on retinoblastoma cells was determined and the efficiency of in vitro MTT assay on drug-screening for retinoblastoma was also evaluated. The results showed that the MTT assay is very useful. The toxicity of radiosensitizers on retinoblastoma cells is dependent on cell line characteristics, drug concentration and time of exposure to it

  4. Re-evaluation of in vitro radiosensitivity of human fibroblasts of different genetic origins

    International Nuclear Information System (INIS)

    Deschavanne, P.J.; Debieu, D.; Malaise, E.P.; Fertil, B.

    1986-01-01

    Statistical analysis of the radiosensitivity of 204 survival curves of non-transformed human fibroblast cell strains of different genetic origins was made using the multi-target one-hit model (characterized by parameters eta and D 0 ), the surviving fraction for a 2 Gy dose (S 2 ) and the mean inactivation dose (D-bar). D-bar is found to be the parameter for characterization of anomalous radiosensitivity linked to a genetic disorder and discrimination between groups of cell strains of differing radiosensitivity. It allows the description of a range of 'normal' radiosensitivity for control fibroblasts and classification of genetic disorders as a function of their mean radiosensitivity expressed in terms of D-bar. Nine groups of cell strains appear to exhibit radiosensitivity differing significantly from the controls: seven groups are hypersensitive (ataxia-telengiectasia homozygotes and heterozygotes, Cockayne's syndrome, Gardner's syndrome, 5-oxoprolinuria homozygotes and heterozygotes, Fanconi's anaemia) and two groups are more radioresistant (fibroblasts from retinoblastoma patients and individuals with chromosome 13 anomalies). Since the coupled parameter eta and D 0 failed to discriminate between the radiosensitivity of the different genetic groups, the use of D-bar to make an intercomparison of intrinsic radiosensitivity of non-transformed human fibroblasts is recommended. (U.K.)

  5. THERMAL RADIOSENSITIZATION IN HEAT-SENSITIVE AND RADIATION-SENSITIVE MUTANTS OF CHO CELLS

    NARCIS (Netherlands)

    KAMPINGA, HH; KANON, B; KONINGS, AWT; STACKHOUSE, MA; BEDFORD, JS

    Recently, it has been hypothesized (Iliakis and Seaner 1990) that DNA double-strand break (dsb) repair proficiency is a prerequisite for heat radiosensitization on the basis of the finding that the radiosensitive and dsb-repair-deficient mutant xrs-5 cell line shows no significant heat-induced

  6. Chromatin structure and cellular radiosensitivity : A comparison of two human tumour cell lines

    NARCIS (Netherlands)

    Woudstra, EC; Roesink, JM; Rosemann, M; Brunsting, JF; Driessen, C; Orta, T; Konings, AWT; Peacock, JH; Kampinga, HH

    1996-01-01

    The role of variation in susceptibility to DNA damage induction was studied as a determinant for cellular radiosensitivity. Comparison of the radiosensitive HX142 and radioresistant RT112 cell lines previously revealed higher susceptibility to X-ray-induced DNA damage in the sensitive cell line

  7. Axin gene methylation status correlates with radiosensitivity of lung cancer cells

    International Nuclear Information System (INIS)

    Yang, Lian-He; Stoecker, Maggie; Wang, Endi; Xu, Ke; Wang, En-Hua; Han, Yang; Li, Guang; Xu, Hong-Tao; Jiang, Gui-Yang; Miao, Yuan; Zhang, Xiu-Peng; Zhao, Huan-Yu; Xu, Zheng-Fan

    2013-01-01

    We previously reported that Axin1 (Axin) is down-regulated in many cases of lung cancer, and X-ray irradiation increased Axin expression and inhibited lung cancer cells. The mechanisms, however, were not clear. Four lung cancer cell lines were used to detect the methylation status of Axin with or without X-ray treatment. Real-time PCR was used to quantify the expression of Axin, and western blot analysis was applied to measure protein levels of Axin, β-catenin, Cyclin D1, MMP-7, DNMTS, MeCP2 and acetylated histones. Flow cytometric analysis, colony formation assay, transwell assay and xenograft growth experiment were used to study the biological behavior of the cells with hypermethylated or unmethylated Axin gene after X-ray treatment. Hypermethylated Axin gene was detected in 2 of 4 cell lines, and it correlated inversely with Axin expression. X-ray treatment significantly up-regulated Axin expression in H446 and H157 cells, which possess intrinsic hypermethylation of the Axin gene (P<0.01), but did not show up-regulation in LTE and H460 cells, which have unmethylated Axin gene. 2Gy X-ray significantly reduced colony formation (from 71% to 10.5%) in H157 cells, while the reduction was lower in LTE cells (from 71% to 20%). After X-ray irradiation, xenograft growth was significantly decreased in H157 cells (from 1.15 g to 0.28 g) in comparison with LTE cells (from 1.06 g to 0.65 g). Significantly decreased cell invasiveness and increased apoptosis were also observed in H157 cells treated with X-ray irradiation (P<0.01). Down-regulation of DNMTs and MeCP2 and up-regulation of acetylated histones could be detected in lung cancer cells. X-ray-induced inhibition of lung cancer cells may be mediated by enhanced expression of Axin via genomic DNA demethylation and histone acetylation. Lung cancer cells with a different methylation status of the Axin gene showed different radiosensitivity, suggesting that the methylation status of the Axin gene may be one important factor

  8. Comparative Radiosensitivity of Pathogenic Bacteria and Viruses

    International Nuclear Information System (INIS)

    Ghys, R.; Vandergoten, R.; Paquette, J.-C.; Fredette, V.; Plante, C.; Pavilanis, V.; Gilker, J.-C.

    1967-01-01

    The authors exposed to gamma rays from a MCo source (''Gammacell 220'' from Atomic Energy of Canada, Ltd.) various pathogenic micro-organisms: a slow-growing aerobic bacterium (Mycobacterium tuberculosis, 10 varieties of the strain B. C. G.), a fast-growing anaerobic bacterium (Clostridium perfringens, strain SWG-121) and 4 strains of influenza virus (2 from group A and 2 from group B). In the case of B. C. G., an LD 90 of 29 ± 1 kR is reported for bacilli irradiated immediately before subculture and subsequently cultivated for at most 14 days. If the microbes are cultivated for 28 days, the yield from cultures after exposures of up to 50 kR is at least equal to that of control specimens; it then decreases rapidly, and a dose of 140 kR inhibits bacterial growth completely. It is reported that the LD 90 of the strain of Cl. perfringens used in the study is very much dependent on die culture conditions and die conditions under which die microbe growth measurements are made; 24 h after irradiation it is at least 1 MR. Although no spores are seen in the microscope, this would seem to demonstrate the presence in the cultures of extremely radioresistant sporulated individuals. Group A influenza viruses are found to be more radioresistant than those of group B. The LD 90 of relatively low radiation doses varies between 75 and 100 kR, and is higher if irradiation is performed at -78.5°C. It is very difficult to inactivate the last virus particles; multiplicity reactivation seems to occur in certain experimental conditions. Haemagglutinant activity does not vary, even after die highest exposures used (4 MR). Two important practical conclusions are drawn: (1) The use of a single dose (e. g. 2.5 Mrad) for radiosterilization gives an exposure which is unnecessarily high in some cases and insufficient in others, and (2) Selective radiosterilization is sometimes possible: the viability of a micro-organism used, for example, to produce a vaccine may not be

  9. Effects of binding metronidazole to a copper-acetate compound on radiosensitizer properties

    International Nuclear Information System (INIS)

    Negron, Ana C. Valderrama; Silva, Denise de Oliveira; Cruz, Aurea S.

    2009-01-01

    Copper compounds exhibit interesting biological properties. Nitroimidazoles show radiosensitizer properties for radiotherapy tumor treatment. In the present work, the effect of binding metronidazole (1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole = MTZ) to copper-acetate on the radiosensitizer properties has been investigated. A compound of copper-acetate-MTZ was prepared and characterized. The experiments were carried out by gamma-irradiation of Hep2 (human larynx cancer) cells under hypoxic conditions. The radiation doses for 50% cell survival in the presence of radiosensitizer were about 8.2 Gy for CuAcMTZ or free MTZ. The effect of binding metronidazole to copper acetate on radiosensitizer properties is mainly related to the radiosensitizer process which involves two events for CuAcMTZ in contrast to one event observed for the MTZ free drug. (author)

  10. Correlation between radiosensitivity of transplanted solid tumor and nutritive condition of host animal

    Energy Technology Data Exchange (ETDEWEB)

    Ando, K [Showa Univ., Tokyo (Japan). School of Medicine

    1975-04-01

    Studies on radiosensitivity of the transplanted tumor were carried out and the following results were obtained: 1. Radiosensitivity of the tumor ran parallel to the growth rate. 2. Malnutrition of the host after irradiation made the tumor radiosensitive, probably because the sublethally damaged tumor cell did not recover. 3. Mitotic index correlated well with radiosensitivity, and the low mitotic index caused by starvation made the tumor cell recover poorly. 4. The DNA synthetic rate measured by means of iodine labeled IUdR did not successfully correlate with the mitotic rate, presumably because of the role of thymidine pool size in this experiment. 5. The serum protein level possibly with the tumor growth, which modified the radiosensitivity. 6. Serum oxygen was difficult to interpret, however, it might be compensated by erythrocytosis in a starved condition.

  11. Synergism between two helper cell subpopulations characterized by different radiosensitivity and nylon adherence

    International Nuclear Information System (INIS)

    Agarossi, G.; Mancini, C.; Doria, G.

    1981-01-01

    The present work extends our previous results on the radiosensitivity of the helper cell function. Two helper cell subpopulations, 1 radiosensitive and the other radioresistant, have been demonstrated in the spleen of mice at different times after priming with HRBC. The radiosensitive subpopulation increases with the increasing time interval between carrier-priming and irradiation. The 2 cell subpopulations have been further characterized by different nylon adherence properties: radioresistant helper cells adhere to nylon wool, whereas radiosensitive cells pass through. The 2 cell subpopulations were separated by x-irradiation and nylon wool filtration, and their helper activity was assessed separately or after recombination. The results favor the notion that 2 functionally independent helper T cells, as characterized by different radiosensitivity and nylon adherence, participate synergistically in the helper activity of primed spleen cells

  12. Evaluation of 2-amino-5-nitrothiazole as a hypoxic cell radiosensitizer

    International Nuclear Information System (INIS)

    Rockwell, S.; Mroczkowski, Z.; Rupp, W.D.

    1982-01-01

    The nitroheterocyclic compound 2-amino-5-nitrothiazole (ANT) was evaluated as a hypoxic radiosensitizer. Experiments with bacteria showed that this agent was similar to misonidozole in radiosensitizing activity, but was less cytotoxic and less mutagenic than misonidazole. Experiments with EMT6 tumor cells in culture showed ANT to be an effective hypoxic radiosensitizer, although slightly less active than misonidazole, and to be less cytotoxic than misonidazole. ANT was more toxic to mice than misonidazole and produced a spectrum of symptoms, including hyperactivity and agitation, different from those of misonidazole. The toxicities of ANT and misonidazole were additive. The maximum levels of ANT achieveable in the tumors after ip injection of nontoxic doses of drug were low ( -4 M) and the radiosensitization obtainable with the drug in vivo was inferior to that obtainable with misonidazole. These findings suggest that nitrothiazoles might be an interesting class of nitroheterocyclic radiosensitizers, but that molecules with increased solubility and improved pharmacokinetics would be necessary for efficacy in vivo

  13. Whole brain radiotherapy with radiosensitizer for brain metastases

    Directory of Open Access Journals (Sweden)

    Viani Gustavo

    2009-01-01

    Full Text Available Abstract Purpose To study the efficacy of whole brain radiotherapy (WBRT with radiosensitizer in comparison with WBRT alone for patients with brain metastases in terms of overall survival, disease progression, response to treatment and adverse effects of treatment. Methods A meta-analysis of randomized controlled trials (RCT was performed in order to compare WBRT with radiosensitizer for brain metastases and WBRT alone. The MEDLINE, EMBASE, LILACS, and Cochrane Library databases, in addition to Trial registers, bibliographic databases, and recent issues of relevant journals were researched. Significant reports were reviewed by two reviewers independently. Results A total of 8 RCTs, yielding 2317 patients were analyzed. Pooled results from this 8 RCTs of WBRT with radiosensitizer have not shown a meaningful improvement on overall survival compared to WBRT alone OR = 1.03 (95% CI0.84–1.25, p = 0.77. Also, there was no difference in local brain tumor response OR = 0.8(95% CI 0.5 – 1.03 and brain tumor progression (OR = 1.11, 95% CI 0.9 – 1.3 when the two arms were compared. Conclusion Our data show that WBRT with the following radiosentizers (ionidamine, metronidazole, misonodazole, motexafin gadolinium, BUdr, efaproxiral, thalidomide, have not improved significatively the overall survival, local control and tumor response compared to WBRT alone for brain metastases. However, 2 of them, motexafin- gadolinium and efaproxiral have been shown in recent publications (lung and breast to have positive action in lung and breast carcinoma brain metastases in association with WBRT.

  14. Electron microscopic study on radiosensitivity of uterine cervical cancer

    Energy Technology Data Exchange (ETDEWEB)

    Iwai, S; Shiozawa, K; Tsukamoto, T; Noguchi, H; Tsukahara, Y [Shinshu Univ., Matsumoto, Nagano (Japan). Faculty of Medicine

    1974-11-01

    The effects of 1000 R of tele-cobalt upon the changes in the primary lesions of uterine cervical cancer with time were studied with an electron microscope. In addition, twenty cases which were proven to have cancer tissues (10 cases of IInd stage of cancer, 8 cases of IIIrd stage of cancer and 2 cases of IVth stage of cancer) were studied. Four cases were favourably sensitive, 7 cases moderately sensitive and 9 cases unfavourably sensitive to radiation. In favourably radio-sensitive cases, the changes in the cancer cells first appeared in the nucleus. There were other changes such as local clumping of chromatin and, specifically, vacuolization of the nucleus. The changes in the endoplasmic reticulum appeared somewhat late. In addition, the disturbance of mitochondria and the decrease or disappearance of ribosomes were specifically due to radiation injury. From the point of view of changes with time, Golgi's apparatus was enlarged and the membrane of the endoplasmic reticulum was degenerated at the 1st day. At the 3rd day, vacuolization of the nucleus appeared, the nuclear corpuscles were increased, the nucleoplasm became thin, and mitochondria was enlarged and degenerated. At the 5th day, the nuclear membrane disappeared, the nucleus was destroyed, large vacuolization of the endoplasmic reticulum was seen, free ribosomes were decreased, and changes around the endoplasmic reticulum were observed. At the 7th day, collagen around the endoplasmic reticulum appeared. In favourably radiosensitive cases, individual tumor cells showed the same degeneration, which fairly corresponded to that evaluated by the histological observation. The disturbance of the cells was caused by radiation, so-called ''burning'' of the cells. Radiation protection of the cells against burning was considered in terms of their radiosensitivity.

  15. A comparative study on radiosensitivity of neonatal ducks and chickens

    International Nuclear Information System (INIS)

    Nakanishi, Y.H.; Ogata, Kenji; Sugimura, Makoto

    1979-01-01

    Neonatal ducks and chickens are exposed to a wholebody X-irradiation ranging from 100 R to 3,000 R at a dose-rate of 185 R per min. Lethal doses to 50% in 30 days are estimated to be 500 R for the ducks, while 800 R for the chickens. The ducks appear to be much more radiosensitive than the chickens. Histopathological observations of various organs of the exposed specimens after death reveal remarkable alterations: Particularly lymphoid organs are affected much more in the ducks than in the chickens at lesser doses than 1,000 R. (author)

  16. Comparative study on radiosensitivity of neonatal ducks and chickens

    Energy Technology Data Exchange (ETDEWEB)

    Nakanishi, Y H; Ogata, K; Sugimura, M [Hokkaido Univ., Sapporo (Japan)

    1979-05-01

    Neonatal ducks and chickens are exposed to a wholebody X-irradiation ranging from 100 R to 3,000 R at a dose-rate of 185 R per min. Lethal doses to 50% in 30 days are estimated to be 500 R for the ducks, while 800 R for the chickens. The ducks appear to be much more radiosensitive than the chickens. Histopathological observations of various organs of the exposed specimens after death reveal remarkable alterations: Particularly lymphoid organs are affected much more in the ducks than in the chickens at lesser doses than 1,000 R.

  17. Influence of physical and biological factors in cellular radiosensitivity

    International Nuclear Information System (INIS)

    García Lima, Omar

    2016-01-01

    The use of therapeutic radiopharmaceuticals is associated with radiation damage, and this at-nuclear physical properties of radionuclides used and the characteristics of the irradiated cells. The work deals with the damage caused by radiation to DNA, factors that condition and tools that can be used to measure it. It presents current concepts of death and cellular radiosensitivity, based on the pioneering work in this field. Enter the neighborhood effect and adaptive response and evaluates the influence of the same in the paradigms of classical radiobiology. (author)

  18. Nervous system disease associated with dominant cellular radiosensitivity

    International Nuclear Information System (INIS)

    Kidson, C.; Chen, P.; Imray, F.P.; Gipps, E.

    1983-01-01

    Ionizing radiation sensitivity has been demonstrated in the following neurological diseases: sporadic and familial Alzheimer's disease, familial non-specific dementia, amyotrophic lateral sclerosis and Parkinsonism dementia of Guam, Huntington's disease, multiple sclerosis. Family studies in many cases give data consistent with dominant genetics, as does cell fusion analysis in the one disease so studied. In no case was there an absolute association between radiosensitivity and a given neurological disease. It is proposed that the underlying mutations are in genes controlling facets of nervous or immune system differentiation and development. 15 references, 2 tables

  19. Assessment of in vitro radiosensitivity of human peripheral blood lymphocytes

    International Nuclear Information System (INIS)

    Knox, S.J.; Shifrine, M.; Rosenblatt, L.S.

    1980-01-01

    The proliferative capacity of sensitive lymphocyte progenitor cells, from thirty-one clinically normal adults, was evaluated following in vitro x-irradiation (0-400R). Radiation effects were studied using both whole blood and lymphocyte-enriched mononuclear cell fractions in the lymphocyte stimulation test and colony formation assay with 6 different mitogens and antigens. Radiation dose-response survival curves were determined for the different test groups. The sensitivity of the different assay systems is compared and normative values are presented that may be used for comparison purposes to determine the relative radiosensitivity of atypical individuals and groups of individuals

  20. Neuropathy of nitroimidazole radiosensitizers: clinical and pathological description

    International Nuclear Information System (INIS)

    Wasserman, T.H.; Nelson, J.S.; VonGerichten, D.

    1984-01-01

    The dose limiting toxicity of the nitroimidazole radiosensitizers is peripherial neuropathy. Improved pharmacology of newer drugs has eliminated the encephalopathy. Peripheral neuropathies are predominently mild to moderate paresthesias of both hands and feet. Subjective changes occur with or without minimal objective changes on neurologic exam. All of the neuropathies occurred within 30 days of the last drug dose and are of varible duration. Sural nerve biopsies from patients indicate progressive axonal degeneration affecting both large and small caliber myelinated fibers. Axonal damage appears to be more severe in the distal portion of the nerves. More data are needed for correlation of clinical and pathological changes

  1. Differential radiosensitivity on a tissue level in Delphinium ajacis

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, S K; Basu, R K [Bose Research Inst., Calcutta (India). Cryogenetics Lab.

    1980-09-01

    Root, leaf, pollen mother cell and endosperm of D.ajacis showed differential sensitivity as measured by X-ray-induced chromosomal aberrations at mitotic anaphase and telophase stages of the first and second division cycles after irradiation. These tissues differed significantly in Interphase Chromosome Volume (ICV) values. In all the tissues the percentage of aberrant cells increased linearly with increase in X-ray dose. Though endosperm had the largest ICV value it was the most radioresistant tissue tested. The relative radiosensitivity of the other 3 tissues was positively correlated with ICV value. The radioresistance of endosperm is probably due to factors unique to this tissue which remained obscure.

  2. Thermoluminescence studies on plant seeds of different radiosensitivity

    International Nuclear Information System (INIS)

    Yamaguchi, Hikoyuki; Eguchi, Hoshio; Koizumi, Yoshinobu.

    1975-01-01

    The thermoluminescence was found when the pulverized powders from the whole seeds of six plant species or the hypocotyls from the seeds of five soybean varieties were irradiated at a liquid nitrogen temperature with gamma-rays. The spectra of luminescence emitted, the light peak temperature, the decaying after irradiation and the dose relationship of luminescence were determined. A high yield of the rapidly-decaying luminescence occurred in the more radiosensitive variety when irradiated with relatively lower doses. The very drastic decrease of the thermoluminescence was observed in the samples irradiated at room temperature prior to the exposure at 77 0 K. (auth.)

  3. Genetic control of radiosensitivity modification of some yeast strons

    International Nuclear Information System (INIS)

    Petin, V.G.; Zhurakovskaya, I.P.

    1982-01-01

    The genetic determination of the relative biological effectiveness (RBE) of densely ionizing particles and cysteamine's radioprotective effect on irradiated cells, demonstrated earlier on yeast cells of different genotype, has been proved on diploid wild-type cells of Saccharomyces cerevisial yeasts, solitary mutants, homozygous with respect to rad 2 and rad 54, and double mutant containing both locuses in homozygous state. It is shown that RBE of α-particles and radioprotector's efficiency depend on repair system's activity. A possible mechanism of the participation of postirradiation recovery processes in the modification of cell radiosensitivity is discussed [ru

  4. Radiosensitizers and the oxygen effects in mammalian cells

    International Nuclear Information System (INIS)

    Millar, B.C.; Fielden, E.M.; Steele, J.J.

    1979-01-01

    The survival curves for Chinese Hamster cells irradiated under various oxygen tensions have been determined. The variation in OER with oxygen concentration shows two distinct components. Between 1.4 and 7.0 μM the OER is constant with a value of 1.9. Experiments with nitroaromatic radiosensitizers in combination with low concentrations of oxygen show that they can all mimic the 'low concentration' oxygen effect. Of the compounds tested only misonidazole can apparently mimic the 'high concentration' oxygen effect although the full OER cannot be obtained with the authors cell line because of toxicity by the sensitizer. (Auth.)

  5. Multiple roles for executive control in belief-desire reasoning: distinct neural networks are recruited for self perspective inhibition and complexity of reasoning.

    Science.gov (United States)

    Hartwright, Charlotte E; Apperly, Ian A; Hansen, Peter C

    2012-07-16

    Belief-desire reasoning is a core component of 'Theory of Mind' (ToM), which can be used to explain and predict the behaviour of agents. Neuroimaging studies reliably identify a network of brain regions comprising a 'standard' network for ToM, including temporoparietal junction and medial prefrontal cortex. Whilst considerable experimental evidence suggests that executive control (EC) may support a functioning ToM, co-ordination of neural systems for ToM and EC is poorly understood. We report here use of a novel task in which psychologically relevant ToM parameters (true versus false belief; approach versus avoidance desire) were manipulated orthogonally. The valence of these parameters not only modulated brain activity in the 'standard' ToM network but also in EC regions. Varying the valence of both beliefs and desires recruits anterior cingulate cortex, suggesting a shared inhibitory component associated with negatively valenced mental state concepts. Varying the valence of beliefs additionally draws on ventrolateral prefrontal cortex, reflecting the need to inhibit self perspective. These data provide the first evidence that separate functional and neural systems for EC may be recruited in the service of different aspects of ToM. Copyright © 2012 Elsevier Inc. All rights reserved.

  6. Hypoxia-induced p53 modulates both apoptosis and radiosensitivity via AKT

    Science.gov (United States)

    Leszczynska, Katarzyna B.; Foskolou, Iosifina P.; Abraham, Aswin G.; Anbalagan, Selvakumar; Tellier, Céline; Haider, Syed; Span, Paul N.; O’Neill, Eric E.; Buffa, Francesca M.; Hammond, Ester M.

    2015-01-01

    Restoration of hypoxia-induced apoptosis in tumors harboring p53 mutations has been proposed as a potential therapeutic strategy; however, the transcriptional targets that mediate hypoxia-induced p53-dependent apoptosis remain elusive. Here, we demonstrated that hypoxia-induced p53-dependent apoptosis is reliant on the DNA-binding and transactivation domains of p53 but not on the acetylation sites K120 and K164, which, in contrast, are essential for DNA damage–induced, p53-dependent apoptosis. Evaluation of hypoxia-induced transcripts in multiple cell lines identified a group of genes that are hypoxia-inducible proapoptotic targets of p53, including inositol polyphosphate-5-phosphatase (INPP5D), pleckstrin domain–containing A3 (PHLDA3), sulfatase 2 (SULF2), B cell translocation gene 2 (BTG2), cytoplasmic FMR1-interacting protein 2 (CYFIP2), and KN motif and ankyrin repeat domains 3 (KANK3). These targets were also regulated by p53 in human cancers, including breast, brain, colorectal, kidney, bladder, and melanoma cancers. Downregulation of these hypoxia-inducible targets associated with poor prognosis, suggesting that hypoxia-induced apoptosis contributes to p53-mediated tumor suppression and treatment response. Induction of p53 targets, PHLDA3, and a specific INPP5D transcript mediated apoptosis in response to hypoxia through AKT inhibition. Moreover, pharmacological inhibition of AKT led to apoptosis in the hypoxic regions of p53-deficient tumors and consequently increased radiosensitivity. Together, these results identify mediators of hypoxia-induced p53-dependent apoptosis and suggest AKT inhibition may improve radiotherapy response in p53-deficient tumors. PMID:25961455

  7. Lung cancer radiosensitization by CMNa in vitro and in vivo

    International Nuclear Information System (INIS)

    Zhang Xia; Ouyang Xienong; Ji Hongbing; Chen Zhonghua; Yang Rujun

    2005-01-01

    Objective: To probe into the radiosensitization effect of CMNa on lung tumor cell lines after γ-irradiation combined with γ-knife to treat patients suffering from lung cancer. Methods: 1. Cells of small cell lung cancer cell line NCI-H446 and non-small cell lung cancer cell line NCI-H596 irradiated with 60 Co γ-rays combined with or without CMNa were counted using trypan blue exclusion methods, and cell survival rate curves were depicted. 2. Patients suffering from lung cancer at different clinical stages were treated using γ-knife combined with or without CMNa, and the curative effect was evaluated 6 weeks after one cycle of treatment. Results: CMNa could significantly increase the sensitivity of lung cancer cell lines to γ-irradiation. Curative effect increased significantly by γ-knife treatment combined with CMNa i. e., the CR+PR rates for these two groups were 47.22% and 37.67% separately (P 0.05). Conclusion: CMNa could significantly increase the radiation sensitivity of lung cancer cell line cells in vitro and tumors in vivo, therefore, it could be used as a radiosensitization agent in clinical treatment of lung cancer. (authors)

  8. Cellular radiosensitivity of small-cell lung cancer cell lines

    International Nuclear Information System (INIS)

    Krarup, Marianne; Poulsen, Hans Skovgaard; Spang-Thomsen, Mogens

    1997-01-01

    Purpose: The objective of this study was to determine the radiobiological characteristics of a panel of small-cell lung cancer (SCLC) cell lines by use of a clonogenic assay. In addition, we tested whether comparable results could be obtained by employing a growth extrapolation method based on the construction of continuous exponential growth curves. Methods and Materials: Fifteen SCLC cell lines were studied, applying a slightly modified clonogenic assay and a growth extrapolation method. A dose-survival curve was obtained for each experiment and used for calculating several survival parameters. The multitarget single hit model was applied to calculate the cellular radiosensitivity (D 0 ), the capacity for sublethal damage repair (D q ), and the extrapolation number (n). Values for α and β were determined from best-fit curves according to the linear-quadratic model and these values were applied to calculate the surviving fraction after 2-Gy irradiation (SF 2 ). Results: In our investigation, the extrapolation method proved to be inappropriate for the study of in vitro cellular radiosensitivity due to lack of reproducibility. The results obtained by the clonogenic assay showed that the cell lines studied were radiobiologically heterogeneous with no discrete features of the examined parameters including the repair capacity. Conclusion: The results indicate that SCLC tumors per se are not generally candidates for hyperfractionated radiotherapy

  9. Protracted postnatal neurogenesis and radiosensitivity in the rabbit's dentate gyrus

    International Nuclear Information System (INIS)

    Gueneau, G.; Baille, V.; Dubos, M.; Court, L.

    1986-01-01

    In the hippocampal formation of a 3-month-old rabbit submitted to a 4.5 Gy gamma irradiation a cytologic study with light and electron microscopy allowed us to make clear the dentate gyrus particular radiosensitivity as soon as the first hours after irradiation. The pycnosis lesion observed in the subgranular zone has drawn our attention in particular. We apply ourselves to describe and precise the lesion and its evolution; thanks to an autoradiographic study, we have shown its link with late postnatal neurogenesis which goes on in this zone and at last we have used the subgranular cells 'radiosensitivity as a biological test allowing to compare the various rays' effects (gamma and neutron rays). In the brain of a one-month-old monkey submitted to a 4 Gy total irradiation the same pycnotic lesion is observed: 1) in the dentate gyrus's subgranular zone and 2) in the cerebellum's outer granular layer. These two postnatal proliferative zones remain particularly sensitive to ionizing radiations. (orig.)

  10. Survey of radiosensitivity in a variety of human cell strains

    Energy Technology Data Exchange (ETDEWEB)

    Arlett, C.F.; Harcourt, S.A.

    1980-03-01

    Gamma-ray sensitivity for cell killing was assayed in 54 human cell strains, including some derived from individuals suffering from certain hereditary diseases. The overall range of Do values in this study was 38 to 180 rads, indicating a considerable range of variability in humans. The normal sensitivity was described by a range of Do values of 97 to 180 rads. All ten ataxia telangiectasia cell strains tested proved radiosensitive and gave a mean Do value of 57 +- 15 (S.E.) rads, and these represent the most radiosensitive human skin fibroblasts currently available. Representative cell strains from familial retinoblastoma, Fanconi's anemia, and Hutchinson-Gilford progeria occupied positions of intermediate sensitivity, as did one of two ataxia telangiectasia heterozygotes. Six xeroderma pigmentosum cell strains together with two Cockayne's syndrome cell strains (all known to be sensitive to ultraviolet light) fell into the normal range, indicating an absence of cross-sensitivity between ultraviolet light and gamma-irradiation.

  11. Radiosensitizing Silica Nanoparticles Encapsulating Docetaxel for Treatment of Prostate Cancer.

    Science.gov (United States)

    Belz, Jodi; Castilla-Ojo, Noelle; Sridhar, Srinivas; Kumar, Rajiv

    2017-01-01

    The applications of nanoparticles in oncology include enhanced drug delivery, efficient tumor targeting, treatment monitoring, and diagnostics. The "theranostic properties" associated with nanoparticles have shown enhanced delivery of chemotherapeutic drugs with superior imaging capabilities and minimal toxicities. In conventional chemotherapy, only a fraction of the administered drug reaches the tumor site or cancer cells. For successful translation of these formulations, it is imperative to evaluate the design and properties of these nanoparticles. Here, we describe the design of ultra-small silica nanoparticles to encapsulate a radiosensitizing drug for combined chemoradiation therapy. The small size of nanoparticles allows for better dispersion and uptake of the drug within the highly vascularized tumor tissue. Silica nanoparticles are synthesized using an oil-in-water microemulsion method. The microemulsion method provides a robust synthetic route in which the inner hydrophobic core is used to encapsulate chemotherapy drug, docetaxel while the outer hydrophilic region provides dispersibility of the synthesized nanoparticles in an aqueous environment. Docetaxel is commonly used for treatment of resistant or metastatic prostate cancer, and is known to have radiosensitizing properties. Here, we describe a systematic approach for synthesizing these theranostic nanoparticles for application in prostate cancer.

  12. Chromosome aberrations in human lymphocytes for investigation of individual radiosensitivity

    International Nuclear Information System (INIS)

    Zitzelsberger, H.; Bauchinger, M.

    2000-01-01

    Stable translocations and insertions which are not selected against during cell proliferation can be reliably scored by use of fluorescence in situ hybridisation (FISH) which allows painting of selected chromosomes along their entire length. This temporal persistence makes them particulary valuable for quantifying post human radiation exposures ('biodosimetry'). A disadvantage of this approach is that for routine use only a partial genome analysis can be performed which is mostly based on triple combinations of DNA probes for particular chromosomes. Translocation frequencies from partial genome analysis are often scaled-up to equal the full genome. Basic assumptions for such scaling are, that double strand breaks leading to translocations must be distributed randomly throughout the genome and no preferential interaction between particular pairs of chromosomes occurs. Thus, the probability of a particular chromosome being involved in an exchange is proportional to its DNA content. However, this is not always supported by experimental findings and may thus indicate a differential radiosensitivity of particular chromosomes. Translocation measurements in peripheral blood of different healthy donors irradiated in vitro with the same dose revealed also some evidence for the existence of interindividual differences in radiosensitivity. Similar findings have been already demonstrated after therapeutic irradiation of tumour patients. Consequences thereof may result for long-term retrospective biodosimetry. In order to provide reliable estimates of an individual's exposure to ionising radiation, the extent, distribution and dose-dependence of the observed variability has to be carefully examined in larger groups of persons and larger sets of calibration data. (orig.) [de

  13. Cellular uptake and radiosensitization of SR-2508 loaded PLGA nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Jin Cheng [Fourth Military Medical University, Department of Radiation Medicine (China); Bai Ling [Xi' an Gaoxin Hospital, Department of Clinical Laboratories (China); Wu Hong [Fourth Military Medical University, Department of Pharmacy (China); Teng Zenghui [Fourth Military Medical University, Department of Pharmacology (China); Guo Guozhen, E-mail: guozhengg@tom.co [Fourth Military Medical University, Department of Radiation Medicine (China); Chen Jingyuan, E-mail: jy_chen@fmmu.edu.c [Fourth Military Medical University, Department of Occupational and Environmental Health (China)

    2008-08-15

    SR-2508 (etanidazole), a hypoxic radiosensitizer, has potential applications in radiotherapy. The poly(d,l-lactide-co-glycolide)(PLGA) nanoparticles containing SR-2508 were prepared by w/o/w emulsification-solvent evaporation method. The physicochemical characteristics of the nanoparticles (i.e. encapsulation efficiency, particle size distribution, morphology, in vitro release) were studied. The cellular uptake of the nanoparticles for the two human tumor cell lines: human breast carcinoma cells (MCF-7) and human carcinoma cervices cells (HeLa), was evaluated by fluorescence microscopy and transmission electronic microscopy. Cell viability was measured by the ability of single cell to form colonies in vitro. The prepared nanoparticles were spherical in shape with size between 90 nm and 190 nm. The encapsulation efficiency was 20.06%. The drug release pattern exhibited an initial burst followed by a plateau for over 24 h. The cellular uptake of nanoparticles was observed. Co-culture of MCF-7 and HeLa cells with SR-2508 loaded nanoparticles showed that released SR-2508 retained its bioactivity and effectively sensitized two hypoxic tumor cell lines to radiation. The radiosensitization of SR-2508 loaded nanoparticles was more significant than that of free drug.

  14. Characteristics of fluorinated nitroazoles as hypoxic cell radiosensitizers

    International Nuclear Information System (INIS)

    Shibamoto, Y.; Nishimoto, S.; Shimokawa, K.

    1989-01-01

    Types of 2-nitroimidazoles and 3-nitro-1,2,4-triazoles bearing one or two fluorine atoms on their side chains were synthesized to evaluate their physicochemical properties, radiosensitizing effects, and toxicity. The reduction potential of the compounds containing one fluorine was similar to that of misonidazole (MISO), whereas that of the difluorinated compounds was slightly higher. Both mono- and difluorinated compounds had an in vitro sensitizing activity comparable to or slightly higher than that of MISO. The fluorinated 3-nitrotriazoles were almost as efficient as the 2-nitroimidazoles with the same substituent. In vivo, some of the compounds were up to twice more efficient than MISO, whereas others were as efficient as MISO. Toxicity in terms of LD50/7 in mice was quite variable depending on the side-chain structure; the amide derivatives were less toxic than MISO, whereas the alcohol and ether derivatives were more toxic. In view of the radiosensitizing effect and toxicity in vivo, at least one compound, KU-2285 (a 2-nitroimidazole with an N1-substituent of: CH2CF2CONHCH2CH2OH) has been found to be as useful a hypoxic cell sensitizer as SR-2508

  15. Biomarkers of Tumour Radiosensitivity and Predicting Benefit from Radiotherapy.

    Science.gov (United States)

    Forker, L J; Choudhury, A; Kiltie, A E

    2015-10-01

    Radiotherapy is an essential component of treatment for more than half of newly diagnosed cancer patients. The response to radiotherapy varies widely between individuals and although advances in technology have allowed the adaptation of radiotherapy fields to tumour anatomy, it is still not possible to tailor radiotherapy based on tumour biology. A biomarker of intrinsic radiosensitivity would be extremely valuable for individual dosing, aiding decision making between radical treatment options and avoiding toxicity of neoadjuvant or adjuvant radiotherapy in those unlikely to benefit. This systematic review summarises the current evidence for biomarkers under investigation as predictors of radiotherapy benefit. Only 10 biomarkers were identified as having been evaluated for their radiotherapy-specific predictive value in over 100 patients in a clinical setting, highlighting that despite a rich literature there were few high-quality studies for inclusion. The most extensively studied radiotherapy predictive biomarkers were the radiosensitivity index and MRE11; however, neither has been evaluated in a randomised controlled trial. Although these biomarkers show promise, there is not enough evidence to justify their use in routine practice. Further validation is needed before biomarkers can fulfil their potential and predict treatment outcomes for large numbers of patients. Copyright © 2015 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

  16. Strain differences in the radiosensitivity of mouse spermatogonia

    CERN Document Server

    Bianchi, M; Hurtado de Catalfo, G; Hendry, J H

    1985-01-01

    The radiosensitivity of spermatogonia was found to be greater by up to a factor of 2 in C3H mice than in B6D2F1 mice, whether assessed for the highly sensitive spermatogonia (types A2 to In) or the much more resistant clonogenic spermatogonia which repopulate tubules. The latter were similarly resistant in the B6D2F1 hybrid and in the DBA2 parent, but were much more sensitive in the C57BL parent strain. A difference in sensitivity by up to a factor of 2 results in a variation by a factor of 10 or more in the level of survival of clonogenic cells after high doses. This variation is also observed when comparing data in the literature from different authors using various strains of mice. Using the radiosensitizer misonidazole, it was shown that hypoxia did not play a major role in the lesser sensitivity demonstrated in B6D2F1 mice. The variation in sensitivity is similar to the range reported in the literature for reciprocal translocations.

  17. Is variation in human radiosensitivity real or artifactual?

    International Nuclear Information System (INIS)

    Nakamura, Nori; Kushiro, Jun-ichi; Sposto, R.; Akiyama, Mitoshi.

    1989-12-01

    Two methods of producing human T-lymphocyte colonies in vitro are described, as well as dose-survival experiments using these methods for the investigation of possible differential radiosensitivity among individuals. In one method, the cloning efficiency (CE) of nonirradiated lymphocytes was between 10 % and 40 % (method 1), whereas subsequent improvement in assay conditions (method 2) resulted in a CE greater than 30 %. In vitro X-irradiation of colonies produced using method 1 revealed that the dose required to kill 90 % of the cells (D 10 ) was 2.87±0.28 Gy (mean ±SD, n = 18) for repeated examinations of lymphocytes from one reference individual. Using method 2, the D 10 values were greater, viz., 3.66±0.21 Gy for 28 repeated tests of the same reference individual and 3.58±0.19 Gy for 31 different individuals. Analysis of variance to compare the data from repeated examinations of one person versus data from single examinations of different persons showed that variation in the D 10 value was not significantly greater in the latter group. These results support the hypothesis that individual variation in human radiosensitivity is quite small, if it exists at all, as far as can be determined by the loss of colony-forming ability of irradiated G 0 lymphocytes. (author)

  18. Gamma radiosensitivity in common bean plant and cowpea

    International Nuclear Information System (INIS)

    Guimaraes, Sandra da Silva; Colaco, Waldeciro

    2002-01-01

    An indispensable step in mutation induction experiments is the determination of the sensitivity to mutagens to be used. Taking this into consideration the radiosensitivity of bean cultivars Carioca, Princesa (P. vulgaris L.), and IPA-206 [V. unguiculata (L.) Walp] to gamma rays from a 60 Co source was evaluated. Sets of seeds (40 seeds/sample) were irradiated with 100, 150, 200, 250 Gy, and compared to a control without irradiation (0 Gy), under greenhouse conditions. Bean and cowpea seeds were respectively inoculated with a suspension of Rhizobium (SEMIA-4077) and Bradyrhizobium (SEMIA-6145) strains. The radiosensitivity was evaluated through seedling height reduction determined at 15 days after emergence (15-DAE), and also through dry matter yield of above-ground part and root nodules at 40-DAE. Seedling height was significantly reduced with increased dose of radiation in relation to the control. The dose causing reduction of 50% seedling height for P. vulgaris cultivar Princesa was set up between 150-250 Gy. Cowpea (IPA-206) was less sensitive to radiation than common bean cultivars, considering the dose range of radiation studied, and a 75% seedling height reduction was reached in the range of 150-250 Gy. Dry mater yield of the above-ground part, root and nodule, were inversely related to the doses. It is recommended a dose range of 300-350 Gy for mutation breeding purposes using the cowpea cultivar (IPA-206). (author)

  19. ATM induction insufficiency in a radiosensitive breast-cancer patient

    International Nuclear Information System (INIS)

    Clarke, R.A.; Fang, Z.H.; Marr, P.J.; Kearsley, J.H.; Papadatos, G.; Lee, C.S.; University of Sydney, Camperdown, NSW

    2002-01-01

    ATM induction insufficiency in a radiosensitive breast-cancer patient The ataxia telangiectasia (A-T) gene (ATM) is a dominant breast cancer gene with tumour suppressor activity. ATM also regulates cellular sensitivity to ionising radiation (IR) presumably through its role as a facilitator of DNA repair. In normal cells and tissues the ATM protein is rapidly induced by IR to threshold/maximum levels. The kinase function of the ATM protein is also rapidly activated in response to IR. The fact that women carriers of ATM mutations can have an increased risk of developing breast cancer and that many sporadic breast tumours have reduced levels of the ATM protein broadens the scope of ATM's tumour suppressor within the breast. This report describes the downregulation of ATM protein levels in a radiosensitive breast cancer patient. Postinduction ATM levels were up to tenfold lower in the patient's fresh tissues compared to normal controls. These results might indicate a much broader role for ATM anomalies in breast cancer aetiology. Copyright (2002) Blackwell Science Pty Ltd

  20. Radiosensitivity of antibody responses and radioresistant secondary tetanus antitoxin responses

    International Nuclear Information System (INIS)

    Stoner, R.; Terres, G.; Cottier, H.; Hess, M.

    1976-01-01

    Primary tetanus antitoxin responses were increasingly repressed in mice when gamma radiation doses of 100 to 400 rads were delivered by whole-body exposure prior to immunization with fluid tetanus toxoid (FTT). Nearly normal secondary antitoxin responses were obtained in mice exposed to 600 rads of gamma radiation 4 days after secondary antigenic stimulation with FTT. A rapid transition from radiosensitivity of the antibody-forming system on days 1 to 3 was followed by relative radioresistance on day 4 after the booster injection of toxoid. Studies on lymphoid cellular kinetics in popliteal lymph nodes after injection of 3 H--thymidine ( 3 H--TdR) and incorporation of 3 H--L-histidine into circulating antitoxin were carried out. Analysis of tritium radioactivity in antigen--antibody precipitates of serums 2 hr after injection of the labeled amino acid revealed maximum incorporation into antibody around day 7 after the booster in nonirradiated controls and about day 12, i.e., 8 days after irradiation, in experimental mice. The shift from radiosensitivity to relative radioresistance was attributed to a marked peak of plasma-cell proliferation in the medulla of lymph nodes on day 3. Many medullary plasma cells survived and continued to proliferate after exposure to radiation. Germinal centers were destroyed by radiation within 1 day. Since antibody formation continued after exposure to radiation and after the loss of germinal centers, this supports the view that germinal-center cells were involved more in the generation of memory cells than in antibody synthesis

  1. LET effects on normal and radiosensitive cell lines

    International Nuclear Information System (INIS)

    Geard, C.R.; Travisano, M.

    1986-01-01

    Charged particles in the track segment mode were produced by the RARAF Van de Graaff accelerator and used to irradiate two CHO cell lines, a radiosensitive hypermutable line EM9 and its normal parent AA8. Asynchronous cells were irradiated attached to 6 micrometer thick Mylar with protons, deuterons and helium-3 particles at LETs ranging from 10 to 150 keV per micrometer. A 50 kVp x-ray tube integrated into the track segment facility provided a low LET comparison. Following irradiation cells were monitored for clonogenicity, and in a separate series of experiments frequencies of sister chromatid exchanges. Up to 9 experiments were carried out at each LET, with a total of 8 radiations of different LETs being compared. The optimally effective LET for cell survival was between 80 and 120 keV per micrometer, with the 150 keV per micrometer particles indicating energy wastage. The differential between the normal and radiosensitive cell lines was maintained at all LETs

  2. 5-Fluorouracil modulation of radiosensitivity in cultured human carcinoma cells

    International Nuclear Information System (INIS)

    Smalley, S.R.; Kimler, B.F.; Evans, R.G.

    1991-01-01

    We evaluated conventional pulse exposure versus continuous exposure models of 5-fluorouracil (5-FU) radiosensitization in HT-29 (human colon adenocarcinoma) and DU-145 (human prostate cancer adenocarcinoma) cell lines. Cell survival following treatment with drug and/or radiation was determined by colony formation assays. Radiation was delivered either by itself, approximately midway through a 1-hr exposure to 5-FU (10 micrograms/ml), or at various times following initiation of exposure to 5-FU (0.5 microgram/ml) present throughout the entire period of incubation. Drug concentrations were selected to approximate those achieved in vivo in humans. HT-29 cells showed a plating efficiency of 87% and similar cytotoxicity (survival reduced to 0.57-0.71) for all 5-FU conditions. The Do's of the radiation survival curves were not different for 1 hr of 5-FU exposure versus radiation alone. However, continuous exposure conditions demonstrated statistically significantly different Do's from radiation alone and pulse 5-FU exposure. DU-145 cells displayed a plating efficiency of 17% and cytotoxicities of 0.10-0.91 for the 5-FU conditions. DU-145 cells showed different radiation 5-FU interactions: 5-FU produced statistically significant changes in Do well as the differences between cell lines insofar as their radiosensitization by 5-FU underscore the caution required in extrapolating these radiobiologic models to the clinical setting

  3. Clinical experience with intravenous radiosensitizers in unresectable sarcomas

    International Nuclear Information System (INIS)

    Kinsella, T.J.; Glatstein, E.

    1987-01-01

    Traditionally, adult bone and soft tissue sarcomas have been considered to be ''radioresistant.'' Because of this philosophy, patients who present with locally advanced, unresectable sarcomas often are treated in a palliative fashion, usually with low-dose radiotherapy. Over the last 6 years, 29 patients with unresectable primary or metastatic sarcomas were treated using a combination of intravenous chemical radiosensitizers and high-dose irradiation. Twenty-two of 29 patients achieved clinical local control, with six patients having a complete clinical response. The time to tumor response is often several months or longer, which is in contrast to other tumor histologies (carcinomas, lymphomas), where tumor response usually occurs over several weeks. Several large tumors have shown only a minimal tumor response, yet were found to be sterilized in posttreatment biopsy or autopsy examination. Of 15 patients with primary sarcomas without metastases, 11 patients (73%) remain free of local tumor progression from 12 to 83 months. Adult high-grade sarcomas can be controlled with high-dose radiotherapy and intravenous radiosensitizers, although the precise role of these agents is unclear

  4. Cellular uptake and radiosensitization of SR-2508 loaded PLGA nanoparticles

    International Nuclear Information System (INIS)

    Jin Cheng; Bai Ling; Wu Hong; Teng Zenghui; Guo Guozhen; Chen Jingyuan

    2008-01-01

    SR-2508 (etanidazole), a hypoxic radiosensitizer, has potential applications in radiotherapy. The poly(d,l-lactide-co-glycolide)(PLGA) nanoparticles containing SR-2508 were prepared by w/o/w emulsification-solvent evaporation method. The physicochemical characteristics of the nanoparticles (i.e. encapsulation efficiency, particle size distribution, morphology, in vitro release) were studied. The cellular uptake of the nanoparticles for the two human tumor cell lines: human breast carcinoma cells (MCF-7) and human carcinoma cervices cells (HeLa), was evaluated by fluorescence microscopy and transmission electronic microscopy. Cell viability was measured by the ability of single cell to form colonies in vitro. The prepared nanoparticles were spherical in shape with size between 90 nm and 190 nm. The encapsulation efficiency was 20.06%. The drug release pattern exhibited an initial burst followed by a plateau for over 24 h. The cellular uptake of nanoparticles was observed. Co-culture of MCF-7 and HeLa cells with SR-2508 loaded nanoparticles showed that released SR-2508 retained its bioactivity and effectively sensitized two hypoxic tumor cell lines to radiation. The radiosensitization of SR-2508 loaded nanoparticles was more significant than that of free drug.

  5. Radiosensitization of nitroindazole derivatives on HeLa cells

    International Nuclear Information System (INIS)

    Wang Hao; Shi Peiji; Zhou Xiaoliang; Wang Yan; Tang Weisheng

    2010-01-01

    Objective: To investigate the cytotoxicity and radiosensitization of 5-nitroindazole-3-formyliminodiacetic acid on HeLa cells. Methods: HeLa cells in exponential growth phase were incubated in culture media with different doses and the survival rate was determined by MTT assay. The survival rate of cells receiving radiation combined with different doses of medicine was compared with that of the control.Results: The cytotoxicity of S-nitroindazole-3-formyliminodiacetic acid on HeLa cells was very low. The drug had hypoxia radiosensitizing effect on HeLa cells. At doses of 0, 6, 12, 24, 48 and 96 μg/ml under hypoxia, the survival rate were 0.91 , 0.87, 0.84, 0.81, 0.76 and 0.60, respectively. At the dosage of 48 and 96 μg/ml, the survival rate were 0.85 and 0.73 under oxygenous). Conclusions: 5-Nitroindazole-3-formyliminodiacetic acid has low cytotoxicity and rediosensitizing effect on HeLa cells. (authors)

  6. Effect of misonidazole on radiosensitivity of Ehrlich ascites tumor cells

    International Nuclear Information System (INIS)

    Takeuchi, Hiroshi

    1986-01-01

    The effect of Misonidazole on radiosensitivity of Ehrlich ascites tumor cells was studied in vivo. Ehrlich ascites tumor cells growing intraperitoneally (ICR/SIC mice) for either 1, 4, 6 or 10 days were irradiated in vivo (whole body irradiation) with or without Misonidazole. Immediately after irradiation tumor cells were transplanted intraperitoneally into new animals. Four days later, the propagated surviving cells were removed and counted for analyses. Enhancement ratio of Misonidazole at the surviving fraction of 0.1 were 1.0 (for 1-day-old), 1.3 (for 4-day-old), 1.9 (for 6-day-old), 1.9 (for 10-day-old) and 2.8 (for anoxic cells) respectively. The gradual increase of the enhancement ratio of the ascites tumore cells during intraperitoneal growth from 1 through 10 days might be attributed to an increase of hypoxic tumor cells. Cytotoxicity was not observed at 0.1 mg per gram body weight of Misonidazole but was at 1 mg per gram body weight of Misonidazole in 6-day-old and 10-day-old Ehrlich ascites tumor cells which were supposed to contain hypoxic cells. These results suggest that Misonidazole may prove an effective radiosensitizer for hypoxic tumor cells. (author)

  7. Radiosensitization in vitro and in vivo by 3-nitrotriazoles

    International Nuclear Information System (INIS)

    Shibamoto, Y.; Sakano, K.; Kimura, R.; Nishidai, T.; Nishimoto, S.; Ono, K.; Kagiya, T.; Abe, M.

    1986-01-01

    A series of 3-nitro-1,2,4-triazole derivatives bearing various types of side chain (R) at the N1-position (AK-2000 series) were synthesized and their radiosensitizing effect and toxicity in vitro and in vivo were investigated, in comparison with those of Misonidazole (MISO), SR-2508, and RSU-1069. Of the fifteen 3-nitrotriazoles tested, all had sensitizing effects in vitro on hypoxic V79 cells. Also, all but one had definite effects on solid EMT6/KU and SCCVII tumors in vivo. For many of the triazole compounds, the degree of radiosensitization in vitro and in vivo appeared identical. However, they were generally less efficient, both in vitro and in vivo, than the corresponding 2-nitroimidazoles, whereas their aerobic cytotoxicity and toxicity to mice (LD50/7) were comparable to those of the 2-nitroimidazoles. Considering the sensitizing effect and toxicity, AK-2123 (R = CH 2 CONHC 2 H 4 OCH 3 ) may be as useful as MISO, but none of the triazoles have been proved to be superior to SR-2508

  8. Glycine and GABAA receptors mediate tonic and phasic inhibitory processes that contribute to prepulse inhibition in the goldfish startle network

    Directory of Open Access Journals (Sweden)

    Paul C.P. Curtin

    2015-03-01

    Full Text Available Prepulse inhibition (PPI is understood as an inhibitory process that attenuates sensory flow during early stages (20-1000ms of information processing. Here, we applied in vivo electrophysiology and pharmacology to determine if prepulse inhibition (PPI is mediated by glycine receptors (GlyRs and/or GABAA receptors (GABAARs in the goldfish auditory startle circuit. Specifically, we used selective antagonists to dissect the contributions of target receptors on sound-evoked postsynaptic potentials (PSPs recorded in the neurons that initiate startle, the Mauthner-cells (M-cell. We found that strychnine, a GlyR antagonist, disrupted a fast-activated (5 ms and rapidly (< 50ms decaying (feed-forward inhibitory process that disrupts PPI at 20 ms prepulse/pulse inter-stimulus intervals (ISI. Additionally we observed increases of the evoked postsynaptic potential (PSP peak amplitude (+87.43 ± 21.53%; N=9 and duration (+204 ± 48.91%, N=9. In contrast, treatment with bicuculline, a GABAAR antagonist, caused a general reduction in PPI across all tested ISIs (20-500 ms, essentially eliminating PPI at ISIs from 20-100 ms. Bicuculline also increased PSP peak amplitude (+133.8 ± 10.3%, N=5 and PSP duration (+284.95 ± 65.64%, N=5. Treatment with either antagonist also tonically increased post-synaptic excitability in the M-cells, reflected by an increase in the magnitude of antidromically-evoked action potentials (APs by 15.07 ± 3.21%, N=7 and 16.23 ± 7.08%, N=5 for strychnine and bicuculline, respectively. These results suggest that GABAARs and GlyRs are functionally segregated to short- and longer-lasting sound-evoked (phasic inhibitory processes that contribute to PPI, with the mediation of tonic inhibition by both receptor systems being critical for gain control within the M-cell startle circuit.

  9. The power of charisma—perceived charisma inhibits the frontal executive network of believers in intercessory prayer

    Science.gov (United States)

    Stødkilde-Jørgensen, Hans; Geertz, Armin W.; Lund, Torben E.; Roepstorff, Andreas

    2011-01-01

    This study used functional magnetic resonance imaging to investigate how assumptions about speakers’ abilities changed the evoked BOLD response in secular and Christian participants who received intercessory prayer. We find that recipients’ assumptions about senders’ charismatic abilities have important effects on their executive network. Most notably, the Christian participants deactivated the frontal network consisting of the medial and the dorsolateral prefrontal cortex bilaterally in response to speakers who they believed had healing abilities. An independent analysis across subjects revealed that this deactivation predicted the Christian participants’ subsequent ratings of the speakers’ charisma and experience of God’s presence during prayer. These observations point to an important mechanism of authority that may facilitate charismatic influence, a mechanism which is likely to be present in other interpersonal interactions as well. PMID:20228138

  10. Potential predictive assay using RAR-β for radiosensitization by 13-cis-retinoic acid and interferonα2a in human carcinoma cells

    International Nuclear Information System (INIS)

    Ryu, Samuel; Nevaldine, Barbara H.; Unguraneau, Carmen; Chung, Chung T.; King, Gerald A.; Stein, Joseph P.

    1997-01-01

    Purpose: Cell culture studies have shown increased cytotoxicity and inhibition of cell proliferation by combined use of 13-cis-retinoic acid (CRA) and interferon-α2a (IFN). Clinically, a direct antitumor activity has been observed by combined use of CRA and IFN in patients with cancer of the cervix and skin. Since IFN is known to enhance radiation response in selected human carcinoma cell lines, we carried out a series of experiments in an effort to improve the efficacy of radiation therapy by CRA and IFN in combination. Materials and Methods: Human cervical carcinoma ME-180 and HeLa cell lines were exposed to 10 μM CRA and 1000 unit/ml IFN in combination for 48 hours prior to radiation. Endpoint of radiosensitization study was colony-forming ability of single cells. Retinoic acid receptors (RAR and RXR) were detected by RNAse protection assay. Apoptosis was quantitated by using immunohistochemical staining method (Apop Tag). The cells were also transfected with bcl-2 or RAR-β gene to explore the mechanism of radiation-induced cell killing. Results: A substantial radiosensitization was observed by the combined use of CRA and IFN in human cervical carcinoma ME-180 cells in culture. The radiation enhancement ratio was 2.0 at 1% cell survival level. The principal mode of radiation-induced cell killing was apoptosis since more than 90% of the ME-180 cells showed evidence of apoptosis by combined treatment of CRA, IFN, and radiation. Both apoptosis and radiosensitization were blocked by transfecting bcl-2 gene into ME-180 cells. In contrast to these results with ME-180 cells, no radiosensitization was observed in HeLa cells by CRA and IFN under the same experimental conditions. Both cell lines express various RXR and RAR mRNAs. However, the RAR-β was undetectable in HeLa cells but present at high levels in ME-180 cells, as determined by RNAse protection assay. Because of this differential expression of RAR-β mRNA, we hypothesized that RAR-β may mediate the

  11. Cytolethal Distending Toxin Enhances Radiosensitivity in Prostate Cancer Cells by Regulating Autophagy

    Directory of Open Access Journals (Sweden)

    Hwai-Jeng Lin

    2017-06-01

    Full Text Available Cytolethal distending toxin (CDT produced by Campylobacter jejuni contains three subunits: CdtA, CdtB, and CdtC. Among these three toxin subunits, CdtB is the toxic moiety of CDT with DNase I activity, resulting in DNA double-strand breaks (DSB and, consequently, cell cycle arrest at the G2/M stage and apoptosis. Radiation therapy is an effective modality for the treatment of localized prostate cancer (PCa. However, patients often develop radioresistance. Owing to its particular biochemical properties, we previously employed CdtB as a therapeutic agent for sensitizing radioresistant PCa cells to ionizing radiation (IR. In this study, we further demonstrated that CDT suppresses the IR-induced autophagy pathway in PCa cells by attenuating c-Myc expression and therefore sensitizes PCa cells to radiation. We further showed that CDT prevents the formation of autophagosomes via decreased high-mobility group box 1 (HMGB1 expression and the inhibition of acidic vesicular organelle (AVO formation, which are associated with enhanced radiosensitivity in PCa cells. The results of this study reveal the detailed mechanism of CDT for the treatment of radioresistant PCa.

  12. N-acetylphytosphingosine enhances the radiosensitivity of tumor cells by increasing apoptosis

    International Nuclear Information System (INIS)

    Han, Y.; Kim, Y.; Yun, Y.; Jeon, S.; Kim, K.; Song, J.; Hong, S.H.; Park, C.

    2005-01-01

    Ceramides are well-known second messengers which mediate apoptosis, proliferation, differentiation in mammalian cells, but the physiological roles of phytosphingosines are poorly understood. We hypothesized that one of the phytosphingosine derivatives, N-acetylphytosphingosine (NAPS) can induce apoptosis in human leukemia Jurkat cell line and increase apoptosis in irradiated MDA-MB-231 cells. We first examined the effect of NAPS on apoptosis of Jurkat cells. NAPS had a more rapid and stronger apoptotic effect than C 2 -ceramide in Jurkat cells and significant increase of apoptosis was observed at 3 h after treatment. In contrast, the apoptosis induced by C2-ceramide was observed only after 16 h of treatment. NAPS induced apoptosis was mediated by caspase 3 and 8 activation and inhibited by z-VAD-fmk. Ceramide plays a pivotal role in radiation induced apoptosis. We postulated that exogenous treatment of NAPS sensitizes tumor cells to ionizing radiation, since NAPS might be used as a more effective alternative to C2-ceramide. As expected, NAPS decreased clonogenic survival of irradiated MDA-MB-231 cells dose dependently, and apoptosis of irradiated cells in the presence of NAPS was increased through the caspase activation. Taken together, NAPS is an effective apoptosis-inducing agent, which can be readily synthesized from yeast sources, and is a potent alternative to ceramide for the further study of ceramide associated signaling and the development of radiosensitizing agent. (orig.)

  13. The alkylphospholipid, perifosine, radiosensitizes prostate cancer cells both in vitro and in vivo

    International Nuclear Information System (INIS)

    Gao, Yuanhong; Ittmann, Michael; Thompson, Timothy C; Butler, E Brian; Xu, Bo; Teh, Bin S; Ishiyama, Hiromichi; Sun, Mianen; Brinkman, Kathryn L; Wang, Xiaozhen; Zhu, Julie; Mai, Weiyuan; Huang, Ying; Floryk, Daniel

    2011-01-01

    Perifosine is a membrane-targeted alkylphospholipid developed to inhibit the PI3K/Akt pathway and has been suggested as a favorable candidate for combined use with radiotherapy. In this study, we investigated the effect of the combined treatment of perifosine and radiation (CTPR) on prostate cancer cells in vitro and on prostate cancer xenografts in vivo. Human prostate cancer cell line, CWR22RV1, was treated with perifosine, radiation, or CTPR. Clonogenic survival assays, sulforhodamine B cytotoxity assays and cell density assays were used to assess the effectiveness of each therapy in vitro. Measurements of apoptosis, cell cycle analysis by flow cytometry and Western blots were used to evaluate mechanisms of action in vitro. Tumor growth delay assays were used to evaluate radiation induced tumor responses in vivo. In vitro, CTPR had greater inhibitory effects on prostate cancer cell viability and clonogenic survival than either perifosine or radiation treatment alone. A marked increase in prostate cancer cell apoptosis was noted in CTPR. Phosphorylation of AKT-T308 AKT and S473 were decreased when using perifosine treatment or CTPR. Cleaved caspase 3 was significantly increased in the CTPR group. In vivo, CTPR had greater inhibitory effects on the growth of xenografts when compared with perifosine or radiation treatment alone groups. Perifosine enhances prostate cancer radiosensitivity in vitro and in vivo. These data provide strong support for further development of this combination therapy in clinical studies

  14. Suppression of topoisomerase IIα expression and function in human cells decreases chromosomal radiosensitivity

    International Nuclear Information System (INIS)

    Terry, Samantha Y.A.; Riches, Andrew C.; Bryant, Peter E.

    2009-01-01

    The mechanism behind chromatid break formation is as yet unclear, although it is known that DNA double-strand breaks (DSBs) are the initiating lesions. Chromatid breaks formed in cells in the G2-phase of the cell-cycle disappear ('rejoin') as a function of time between radiation exposure and cell fixation. However, the kinetics of disappearance of chromatid breaks does not correspond to those of DSB rejoining, leading us to seek alternative models. We have proposed that chromatid breaks could be formed indirectly from DSB and that the mechanism involves topoisomerase IIα. In support of this hypothesis we have recently shown that frequencies of radiation-induced chromatid breaks are lower in two variant human promyelocytic leukaemic cell lines with reduced topoisomerase IIα expression. Here we report that suppression of topoisomerase IIα in human hTERT-RPE1 cells, either by its abrogation using specific siRNA or by inhibition of its catalytic activity with the inhibitor ICRF-193, causes a reduction in frequency of chromatid breaks in radiation-exposed cells. The findings support our hypothesis for the involvement of topoisomerase IIα in the formation of radiation-induced chromatid breaks, and could help explain inter-individual variation in human chromosomal radiosensitivity; elevation of which has been linked with cancer susceptibility.

  15. Networking

    OpenAIRE

    Rauno Lindholm, Daniel; Boisen Devantier, Lykke; Nyborg, Karoline Lykke; Høgsbro, Andreas; Fries, de; Skovlund, Louise

    2016-01-01

    The purpose of this project was to examine what influencing factor that has had an impact on the presumed increasement of the use of networking among academics on the labour market and how it is expressed. On the basis of the influence from globalization on the labour market it can be concluded that the globalization has transformed the labour market into a market based on the organization of networks. In this new organization there is a greater emphasis on employees having social qualificati...

  16. Drug priming enhances radiosensitivity of adamantinomatous craniopharyngioma via downregulation of survivin.

    Science.gov (United States)

    Stache, Christina; Bils, Christiane; Fahlbusch, Rudolf; Flitsch, Jörg; Buchfelder, Michael; Stefanits, Harald; Czech, Thomas; Gaipl, Udo; Frey, Benjamin; Buslei, Rolf; Hölsken, Annett

    2016-12-01

    radiotherapy, reduced survivin levels in vitro. Accordingly, ACP showed reduced cell viability and proliferation after survivin downregulation by siRNA. CONCLUSIONS These results indicate an impact of EGFR signaling on radioresistance in ACP. Inhibition of EGFR activity by means of TKI treatment acts as a radiosensitizer on ACP tumor cells, leading to increased cell death. Additionally, the results emphasize the antiapoptotic and pro-proliferative role of survivin in ACP biology and its regulation by EGFR signaling. The suppression of survivin by treatment with TKI and combined radiotherapy represents a new promising treatment strategy that will be further assessed in in vivo models of ACP.

  17. Gemcitabine radiosensitizes multiple myeloma cells to low let, but not high let, irradiation

    International Nuclear Information System (INIS)

    Supiot, Stephane; Thillays, Francois; Rio, Emmanuel; Gouard, Sebastien; Morgenstern, Alfred; Bruchertseifer, Frank; Mahe, Marc-Andre; Chatal, Jean-Francois; Davodeau, Francois; Cherel, Michel

    2007-01-01

    The radiosensitizing properties of gemcitabine in relation to low Linear Energy Transfer (LET) particles (Cobalt 60) and high-LET particles (alpha-RIT 213 Bi-radiolabeled CHX-DTPA-B-B4) were analyzed. Three multiple myeloma cell lines (LP1, RPMI 8226, U266) were irradiated with or without 10 nM gemcitabine 24 h prior to radiation. Gemcitabine led to radiosensitization of LP1 and U266 cells with low-LET (Radiation Enhancement Ratio: 1.55 and 1.49, respectively) but did not radiosensitize any cell line when combined with high-LET

  18. Bacterial radiosensitivity to gamma and ultraviolet. Compositional dependence and repair mechanisms

    International Nuclear Information System (INIS)

    Saez Angulo, R. M.; Davila, C. A.

    1974-01-01

    The gamma and ultraviolet radiosensitivity of several species of bacteria has been determined its dependence on DNAs composition and repair processes has been studied. Base composition are evaluated by chromatography, DNA melting temperature and isopycnic sedimentation on CsCl gradient. Repair capacity of gamma -and UV- lesions has been studied in two bacterial strains with same DMA base composition. It is concluded that the postulated correlation between radiosensitivity and base composition can not be generalized, the enzymatic repair mechanisms being of determining on radiosensitivity. (Author) 248 refs

  19. Radiosensitization of mouse spermatogenic stem cells by Ro-07-0582

    International Nuclear Information System (INIS)

    Suzuki, N.; Withers, R.; Hunter, N.

    1977-01-01

    The hypoxic character of the spermatogenic stem cells of the mouse testis was investigated by measuring the effect on radiosensitivity of treatment with the hypoxic cell radiosensitizer, Ro-07-0582 or hyperbaric oxygen (30 psi). The D 0 values obtained were 181 (161-207) rad for irradiation alone, 140 (133-148) rad for irradiation after treatment with Ro-07-0582, and about 100 rad for irradiation in the presence of hyperbaric oxygen. Ro-07-0582 alone was slightly cytotoxic. The results demonstrate that mouse spermatogenic stem cells are radiosensitized by Ro-07-0582 or hyperbaric oxygen and are not as well oxygenated as other normal tissues

  20. Dopamine-signalled reward predictions generated by competitive excitation and inhibition in a spiking neural network model

    Directory of Open Access Journals (Sweden)

    Paul eChorley

    2011-05-01

    Full Text Available Dopaminergic neurons in the mammalian substantia nigra displaycharacteristic phasic responses to stimuli which reliably predict thereceipt of primary rewards. These responses have been suggested toencode reward prediction-errors similar to those used in reinforcementlearning. Here, we propose a model of dopaminergic activity in whichprediction error signals are generated by the joint action ofshort-latency excitation and long-latency inhibition, in a networkundergoing dopaminergic neuromodulation of both spike-timing dependentsynaptic plasticity and neuronal excitability. In contrast toprevious models, sensitivity to recent events is maintained by theselective modification of specific striatal synapses, efferent tocortical neurons exhibiting stimulus-specific, temporally extendedactivity patterns. Our model shows, in the presence of significantbackground activity, (i a shift in dopaminergic response from rewardto reward predicting stimuli, (ii preservation of a response tounexpected rewards, and (iii a precisely-timed below-baseline dip inactivity observed when expected rewards are omitted.

  1. Gimeracil, an inhibitor of dihydropyrimidine dehydrogenase, inhibits the early step in homologous recombination

    International Nuclear Information System (INIS)

    Sakata, Koh-ichi; Someya, Masanori; Matsumoto, Yoshihisa; Takagi, Masaru; Hareyama, Masato; Tauchi, Hiroshi; Kai, Masahiro; Toyota, Minoru; Fukushima, Masakazu

    2011-01-01

    Gimeracil (5-chloro-2, 4-dihydroxypyridine) is an inhibitor of dihydropyrimidine dehydrogenase (DPYD), which degrades pyrimidine including 5-fluorouracil in the blood. Gimeracil was originally added to an oral fluoropyrimidine derivative S-1 to yield prolonged 5-fluorouracil concentrations in serum and tumor tissues. We have already reported that gimeracil had radiosensitizing effects by partially inhibiting homologous recombination (HR) in the repair of DNA double strand breaks. We investigated the mechanisms of gimeracil radiosensitization. Comet assay and radiation-induced focus formation of various kinds of proteins involved in HR was carried out. Small interfering RNA (siRNA) for DPYD were transfected to HeLa cells to investigate the target protein for radiosensitization with gimeracil. SCneo assay was carried out to examine whether DPYD depletion by siRNA inhibited HR repair of DNA double strand breaks. Tail moments in neutral comet assay increased in gimeracil-treated cells. Gimeracil restrained the formation of foci of Rad51 and replication protein A (RPA), whereas it increased the number of foci of Nbs1, Mre11, Rad50, and FancD2. When HeLa cells were transfected with the DPYD siRNA before irradiation, the cells became more radiosensitive. The degree of radiosensitization by transfection of DPYD siRNA was similar to that of gimeracil. Gimeracil did not sensitize DPYD-depleted cells. Depletion of DPYD by siRNA significantly reduced the frequency of neopositive clones in SCneo assay. Gimeracil partially inhibits the early step in HR. It was found that DPYD is the target protein for radiosensitization by gimeracil. The inhibitors of DPYD, such as gimeracil, could enhance the efficacy of radiotherapy through partial suppression of HR-mediated DNA repair. (author)

  2. Effect of DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine on radiosensitivity of the human lung cancer cells in three-dimensional culture

    International Nuclear Information System (INIS)

    Pan Dong; Xue Gang; Li Xiaoman; Chen Yaxiong; Ren Zhenxin; Du Yarong; Hu Burong

    2014-01-01

    5-Aza-CdR is a specific inhibitor of DNMTs which could suppress tumor growth by demethylation of genomic DNA. There have only few studies thus far concerning it as radiosensitizers in three-dimensional (3D) cells. The principal aim of this study is to evaluate the effects of 5-Aza-CdR on the radiosensitivity of A549 cells in monolayer (2D) and 3D cultures in an attempt to find out a new combination treatments with radiotherapy. The cell proliferation was detected by MTT assay after pretreated with different doses of 5-Aza-CdR for 72 h. A549 cells were treated with or without 5-Aza-CdR (2, 5 μmol/L) for 72 h before be exposed to X-rays of 1, 2, 4, 6 Gy, respectively. The DNA damage was evaluated by micronucleus assay and clonogenic assays. Pretreatment with 5-Aza-CdR inhibited the A549 cell proliferation significantly. More micronucleus were observed after irradiation in 3D cells pretreated with 2 and 5 μmol/L concentration of drug than those without treatment. The survival fractions of cells pretreated by both 2 and 5 μmol/L drug reduced significantly in 3D cultures after irradiation. These significances, however, were found in 2D cells pretreated by only 5 μmol/L drug. Our results suggest that 5-Aza-CdR can inhibit the A549 cells proliferation and apparently enhance the radiosensitivity of cells in 3D cultures. Using of the low dose 5-Aza-CdR in clinical radiotherapy may reduce side effects and enhance effectively the cancer target therapy. (authors)

  3. The combination of hyperthermia or chemotherapy with gimeracil for effective radiosensitization

    Energy Technology Data Exchange (ETDEWEB)

    Takagi, M.; Sakata, K.; Someya, M.; Hareyama, M. [Sapporo Medical Univ. (Japan). Dept. of Radiology; Matsumoto, Y. [Tokyo Institute of Technology, Tokyo (Japan). Research Laboratory for Nuclear Reactors; Tauchi, H. [Ibaraki Univ. (Japan). Dept. of Environmental Sciences; Fukushima, M. [Taiho Pharmaceutical Co., Ltd., Tokushima (Japan). Pharmacokinetics Research Lab.

    2012-03-15

    5-chloro-2,4-dihydroxypyridine (gimeracil) is a component of the oral fluoropyrimidine derivative S-1. Gimeracil was originally added to S-1 to yield prolonged 5-fluorouracil (5-FU) concentrations in serum and tumor tissues by inhibiting dihydropyrimidine dehydrogenase, which degrades 5-FU. We previously demonstrated that gimeracil enhances the efficacy of radiotherapy through the suppression of homologous recombination (HR) in DNA double strand repair. The goal of this paper was to examine the effects of gimeracil on the sensitivity of anticancer drugs and hyperthermia in order to obtain effective radiosensitization. Various cell lines, including DLD 1 (human colon carcinoma cells) and cells deficient in HR or nonhomologous end-joining (NHEJ), were used in clonogenic assays. The survival of these cells after various treatments (e.g., drug treatment, heat treatment, and radiation) was determined based on their colony-forming ability. Gimeracil enhanced cell-killing effects of camptothecin (CPT), 5-FU, and hydroxyurea. Gimeracil sensitized effects of CPT or 5-FU to cells deficient in HR or NHEJ to a similar extent as in other cells (DLD1 and a parent cell), indicating that its sensitizing mechanisms may be different from inhibition of HR or NHEJ. Combination of gimeracil and CPT or 5-FU sensitized radiation more effectively than each modality alone. Gimeracil also enhanced heat sensitivity at 42 C or more. The degree of heat sensitization with gimeracil increased as the temperature increased, and the combination of gimeracil and heat-sensitized radiation was more effective than each modality alone. Gimeracil enhanced sensitivity of CPT, 5-FU, and hyperthermia. Combination of these modalities sensitized radiation more efficiently than each modality alone.

  4. Radiosensitizing Effect of a Phenylbutyrate-Derived Histone Deacetylase Inhibitor in Hepatocellular Carcinoma

    International Nuclear Information System (INIS)

    Lu, Yen-Shen; Chou, Chia-Hung; Tzen, Kai-Yuan; Gao, Ming; Cheng, Ann-Lii; Kulp, Samuel K.; Cheng, Jason Chia-Hsien

    2012-01-01

    Purpose: Radiotherapy is integrated into the multimodal treatment of localized hepatocellular carcinoma (HCC) refractory to conventional treatment. Tumor control remains unsatisfactory and the sublethal effect associates with secondary spread. The use of an effective molecularly targeted agent in combination with radiotherapy is a potential therapeutic approach. Our aim was to assess the effect of combining a phenylbutyrate-derived histone deacetylase (HDAC) inhibitor, AR-42, with radiotherapy in in vitro and in vivo models of human HCC. Methods and Materials: Human HCC cell lines (Huh-7 and PLC-5) were used to evaluate the in vitro synergism of combining AR-42 with irradiation. Flow cytometry analyzed the cell cycle changes, whereas Western blot investigated the protein expressions after the combined treatment. Severe combined immunodeficient (SCID) mice bearing ectopic and orthotopic HCC xenografts were treated with AR-42 and/or radiotherapy for the in vivo response. Results: AR-42 significantly enhanced radiation-induced cell death by the inhibition of the DNA end-binding activity of Ku70, a highly versatile regulatory protein for DNA repair, telomere maintenance, and apoptosis. In ectopic xenografts of Huh-7 and PLC-5, pretreatment with AR-42 significantly enhanced the tumor-suppressive effect of radiotherapy by 48% and 66%, respectively. A similar combinatorial effect of AR-42 (10 and 25 mg/kg) and radiotherapy was observed in Huh-7 orthotopic model of tumor growth by 52% and 82%, respectively. This tumor suppression was associated with inhibition of intratumoral Ku70 activity as well as reductions in markers of HDAC activity and proliferation, and increased apoptosis. Conclusion: AR-42 is a potent, orally bioavailable inhibitor of HDAC with therapeutic value as a radiosensitizer of HCC.

  5. Hypoxic cell radiosensitization by moderate hyperthermia and glucose deprivation

    International Nuclear Information System (INIS)

    Kim, J.H.; Kim, S.H.; Hahn, E.W.

    1983-01-01

    Cell culture studies were carried out to determine whether moderate hyperthermia reduces the oxygen enhancement ratio of cells under well-defined cultural conditions. Using asynchronously growing HeLa cells, the OER of cells with and without glucose was determined following exposure of cells to moderate hyperthermia, 40.5omicronC for 1 hr, immediately after X irradiation. The OER of cells with 5 mM glucose was 3.2, whereas the OER of glucose-deprived cells was reduced to 2.0. The pH of the cell culture medium was kept at 7.4 throughtout the experiments. The present finding may provide a clue toward further enhancing the radiosensitization of hypoxic cells by heat

  6. Hypoxic cell radiosensitization by moderate hyperthermia and glucose deprivation

    International Nuclear Information System (INIS)

    Kim, J.H.; Kim, S.H.; Hahn, E.W.

    1983-01-01

    Cell culture studies were carried out to determine whether moderate hyperthermia reduces the oxygen enhancement ratio of cells under well-defined cultural conditions. Using asynchronously growing HeLa cells, the OER of cells with and without glucose was determined following exposure of cells to moderate hyperthermia, 40.5 degrees C for 1 hr, immediately after X irradiation. The OER of cells with 5 mM glucose was 3.2, whereas the OER of glucose-deprived cells was reduced to 2.0. The pH of the cell culture medium was kept at 7.4 throughout the experiments. The present finding may provide a clue toward further enhancing the radiosensitization of hypoxic cells by heat

  7. Dissociative electron attachment to the radiosensitizing chemotherapeutic agent hydroxyurea

    Science.gov (United States)

    Huber, S. E.; Śmiałek, M. A.; Tanzer, K.; Denifl, S.

    2016-06-01

    Dissociative electron attachment to hydroxyurea was studied in the gas phase for electron energies ranging from zero to 9 eV in order to probe its radiosensitizing capabilities. The experiments were carried out using a hemispherical electron monochromator coupled with a quadrupole mass spectrometer. Diversified fragmentation of hydroxyurea was observed upon low energy electron attachment and here we highlight the major dissociation channels. Moreover, thermodynamic thresholds for various fragmentation reactions are reported to support the discussion of the experimental findings. The dominant dissociation channel, which was observed over a broad range of energies, is associated with formation of NCO-, water, and the amidogen (NH2) radical. The second and third most dominant dissociation channels are associated with formation of NCNH- and NHCONH2-, respectively, which are both directly related to formation of the highly reactive hydroxyl radical. Other ions observed with significant abundance in the mass spectra were NH2-/O-, OH-, CN-, HNOH-, NCONH2-, and ONHCONH2-.

  8. Intrinsic radiosensitivity and PLD repair in osteosarcoma cell lines

    International Nuclear Information System (INIS)

    Sugimoto, M.; Toguchida, J.; Kotoura, Y.; Yamamuro, T.; Utsumi, H.

    1992-01-01

    The response to radiation of seven osteosarcoma cell lines was analysed by in vitro colony-forming assay and compared with that of eight human fibroblast strains. The values of D 0 , the surviving fraction after 2 Gy (S2Gy), and the mean inactivation dose (D-bar) of osteosarcoma cells in log-phase culture were significantly higher than those of fibroblast strains (p<0.01). PLD (potentially lethal damage) repair of osteosarcoma cells evaluated in the plateau phase of growth showed great variation for enhancement of survival, although all of the values were maximised within 12 h after irradiation. In the osteosarcoma, intrinsic radiosensitivity in vitro reflected the clinical response to radiation. However, the capacity for PLD repair might not be a good indicator for predicting the results of radiation therapy. (author)

  9. Nanoparticle Drones to Target Lung Cancer with Radiosensitizers and Cannabinoids

    Directory of Open Access Journals (Sweden)

    Wilfred Ngwa

    2017-09-01

    Full Text Available Nanotechnology has opened up a new, previously unimaginable world in cancer diagnosis and therapy, leading to the emergence of cancer nanomedicine and nanoparticle-aided radiotherapy. Smart nanomaterials (nanoparticle drones can now be constructed with capability to precisely target cancer cells and be remotely activated with radiation to emit micrometer-range missile-like electrons to destroy the tumor cells. These nanoparticle drones can also be programmed to deliver therapeutic payloads to tumor sites to achieve optimal therapeutic efficacy. In this article, we examine the state-of-the-art and potential of nanoparticle drones in targeting lung cancer. Inhalation (INH (air versus traditional intravenous (“sea” routes of navigating physiological barriers using such drones is assessed. Results and analysis suggest that INH route may offer more promise for targeting tumor cells with radiosensitizers and cannabinoids from the perspective of maximizing damage to lung tumors cells while minimizing any collateral damage or side effects.

  10. Chromosomal radiosensitivity, cancer predisposition and response to radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Scott, D. [Christie Hospital, Manchester (United Kingdom). Paterson Inst. for Cancer Research

    2000-05-01

    Aim: This paper briefly summarizes the research on this topic, undertaken in the Department of Cancer Genetics, Paterson Institute for Cancer Research, Manchester, England, over the previous 6 years. We have investigated the possible role of radiosensitivity as a marker of cancer predisposition and response to radiotherapy in the general population. Results: We found that 42% (57/135) of breast cancer patients exhibit chromosomal radiosensitivity when lymphocytes are irradiated in the G{sub 2} phase of the cell cycle, compared with 6% (6/105) of healthy controls. These figures are much higher than the estimated frequencies of carriers of the ataxia-telangiectasia gene (heterozygotes) amongst breast cancer patients (<5%) and control (0.5%). We have also obtained evidence of heritability of G{sub 2} sensitivity by studying relatives of breast cancer cases. The pattern of inheritance is relatively simple and attributable to 1 or 2 genes segregating in each family. In a prospective study of 123 breast cancer patients, 9 (7%) had severe acute reactions to radiotherapy and their mean G{sub 2} sensitivity was significantly greater (p=0.001) than that of the remaining patients. In 16 patients with adverse acute reactions we found no mutations of the ataxia-telangiectasia gene (ATM). Using another chromosomal assay (micronucleus induction in G{sub 0} lymphocytes) we found that the mean radiosensitivity of patients with severe late reactions was higher than that of normal reactors. For example, 8 patients with severe fibrosis were more sensitive (p=0.055) than 39 patients with a normal response. However, the discriminatory power of these chromosomal assays is too low for them to be used alone in a clinical setting. Conclusion: Our results provide good evidence that genes other than ATM, that confer chromosomal radiosensitivity, are involved in low penetrance predisposition to breast cancer in a high proportion of cases and contribute to adverse reactions after radiotherapy

  11. Isolation of microorganisms from red pepper powder and their radiosensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Choi, E H; Kim, Y B; Lee, S R [Korea Atomic Energy Research Inst., Seoul (Republic of Korea)

    1977-01-01

    From samples of red pepper powder sold in Korea were isolated and identified 13 species of molds (Aspergillus amsteodami, Asp. chevalieri, Asp. clavatus, Asp. Flavus, Asp. janus var. effusus, Asp. oryzae, Asp. oryzae var. brevis, Asp. repens, Asp. sydowi, Asp. thomii, Asp. tubingensis, Penicillium thomii, Scopulariopsis brevicaulis) and 5 species of bacteria (Bacillus pumilus, Bac. subtilis, Micrococus luteus, M. varians, Staphylococcus aureus). Radiosensitivity of these microorganisms was examined to give D/sub 10/ values of 14-41 krad for molds, 11-24 krad for bacterial vegetative cells and 190-250 krad for bacterial spores. The red pepper powder was contaminated with 2-3x10/sup 2/ mold counts/g and 3-6x10/sup 7/ bacterial counts/g, which would be sufficiently destroyed by irradiating 200 krad r-rays.

  12. Intracellular and extracellular radiosensitization of Serratia marcescens by bipyridinium compounds

    International Nuclear Information System (INIS)

    Anderson, R.F.; Patel, K.B.

    1979-01-01

    The one-electron reduced form of the bipyridinium compounds benzylviologen and methylviologen have been found to diffuse across the cytoplasmic membrane of Serratia marcescens cells. Subsequent reoxidation of the viologens to the dicationic form traps the compound inside the cells. Cells at a density of 4 x 10 9 ml -1 took up approximately half of the compound when incubated with an initial extracellular concentration of 200μM of either reduced viologen. The degree of radiosensitization in anoxia afforded by the compounds parallels the rise in internal concentration and reaches a maximum enhancement ratio of 2.0 +- 0.1 for both compounds. This level in sensitization is similar to that found when the compounds are external to the cell. No additivity in sensitization is found when the viologens are both internal and external to the cells at the time of irradiation suggesting that the same target