Inhibition of autophagy induced by TSA sensitizes colon cancer cell to radiation.

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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.

Relationship of radiation sensitivity and aberrant DNA synthesis in repair deficient CHO cells

International Nuclear Information System (INIS)

Newman, C.N.; Hagler, H.; Miller, J.H.

1986-11-01

Comparison of alkaline sucrose gradient profiles of pulse-labeled DNA from a normal CHO cell line and its radiation-sensitive mutant, xrs-5, reveals significant differences in the replicon elongation/maturation process in these two cells. During a one hr period of growth subsequent to labeling, the molecular weight of pulse-labeled DNA from the mutant cell increases considerably more rapidly than that of the parent cell. For xrs-5, the presence of 2 mM deoxycytidine (CdR) in the culture medium reduces the replication rate to one approaching that of the parent cell growing in the standard medium. Corresponding uv resistance of the mutant likewise increases to nearly that of the parent cell line. These results suggest that the locus conferring radiation sensitivity to xrs-5 affects the DNA replisome complex and that replicative activity and radiation sensitivity are jointly modulated by CdR. 19 refs., 4 figs

Sensitivity of hyperthermia-treated human cells to killing by ultraviolet or gamma radiation

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Mitchel, R.E.; Smith, B.P.; Wheatly, N.; Chan, A.; Child, S.; Paterson, M.C.

1985-01-01

Human xeroderma pigmentosum (XP) or Fanconi anemia (FA) fibroblasts displayed shouldered 45 0 C heat survival curves not significantly different from normal fibroblasts, a result similar to that previously found for ataxia telangiectasia (AT) cells, indicating heat resistance is not linked to either uv or low-LET ionizing radiation resistance. Hyperthermia (45 0 C) sensitized normal and XP fibroblasts to killing by gamma radiation but failed to sensitize the cells to the lethal effects of 254 nm uv radiation. Thermal inhibition of repair of ionizing radiation lesions but not uv-induced lesions appears to contribute synergistically to cell death. The thermal enhancement ratio (TER) for the synergistic interaction of hyperthermia (45 0 C, 30 min) and gamma radiation was significantly lower in one FA and two strains (TER = 1.7-1.8) than that reported previously for three normal strains (TER = 2.5-3.0). These XP and FA strains may be more gamma sensitive than normal human fibroblasts. Since hyperthermia treatment only slightly increases the gamma-radiation sensitivity of ataxia telangiectasia (AT) fibroblasts compared to normal strains, it is possible that the degree of thermal enhancement attainable reflects the genetically inherent ionizing radiation repair capacity of the cells. The data indicate that both repair inhibition and particular lesion types are required for lethal synergism between heat and radiation. We therefore postulate that the transient thermal inhibition of repair results in the conversion of gamma-induced lesions to irrepairable lethal damage, while uv-type damage can remain unaltered during this period

Intervention of oxygen-control ability to radiation sensitivity, cell aging and cell transformation

International Nuclear Information System (INIS)

Yoshii, Hanako; Watanabe, Masami

2009-01-01

Oxygen is essential for life, and cells have therefore developed numerous adaptive responses to oxygen change. Here, we examined the difference in oxygen-control functions of human (HE), mouse (ME), and Syrian hamster embryo (SHE) cells cultured under different oxygen conditions (0.5%, 2% and 20%), and also examined whether oxygen tensions contributed to cellular lifespan and transformation. HE cells had their replicative lifespan slightly extended under hypoxic (0.5% and 2% oxygen) conditions, but were not immortalized under any of the oxygen concentrations. On the other hand, although ME cells cultured under 20% oxygen tension decreased their proliferation potency temporarily at early stage, all rodent cells were immortalized and acquired anchorage-independency, regardless of oxygen tension. These results suggest that cellular oxygen control function is related to sensitivities cellular immortalization and transformation. To understand intervention of oxygen control ability on cellular immortalization and transformation, we examined the intracellular oxidative level, mitochondria functions and radiation sensitivity. Intracellular oxidative levels of hypoxically cultured rodent cells were significantly enhanced. Mitochondrial membrane potential was altered depend on oxygen tensions, but the change was not parallel to mitochondria number in rodent cells. ME cells were particularly sensitive to oxygen change, and showed a clear oxygen effect on the X-ray survival. However, there was no difference in frequency of radiation-induced micronuclei between HE and ME cells. These results suggest that the response to oxygen change differs markedly in HE and rodent cells. (author)

Genetic and epigenetic features in radiation sensitivity. Part I: Cell signalling in radiation response

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Bourguignon, Michel H.; Gisone, Pablo A.; Perez, Maria R.; Michelin, Severino; Dubner, Diana; Giorgio, Marina di; Carosella, Edgardo D.

2005-01-01

Recent progress especially in the field of gene identification and expression has attracted greater attention to genetic and epigenetic susceptibility to cancer, possibly enhanced by ionising radiation. It has been proposed that the occurrence and severity of the adverse reactions to radiation therapy are also influenced by such genetic susceptibility. This issue is especially important for radiation therapists since hypersensitive patients may suffer from adverse effects in normal tissues following standard radiation therapy, while normally sensitive patients could receive higher doses of radiation offering a better likelihood of cure for malignant tumours. This paper, the first of two parts, reviews the main mechanisms involved in cell response to ionising radiation. DNA repair machinery and cell signalling pathways are considered and their role in radiosensitivity is analysed. The implication of non-targeted and delayed effects in radiosensitivity is also discussed. (orig.)

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

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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)

Modulation of DNA methylation levels sensitizes doxorubicin-resistant breast adenocarcinoma cells to radiation-induced apoptosis

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Luzhna, Lidia [Department of Biological Sciences, University of Lethbridge, AB, Canada T1K 3M4 (Canada); Kovalchuk, Olga, E-mail: olga.kovalchuk@uleth.ca [Department of Biological Sciences, University of Lethbridge, AB, Canada T1K 3M4 (Canada)

2010-02-05

Chemoresistant tumors often fail to respond to other cytotoxic treatments such as radiation therapy. The mechanisms of chemo- and radiotherapy cross resistance are not fully understood and are believed to be epigenetic in nature. We hypothesize that MCF-7 cells and their doxorubicin-resistant variant MCF-7/DOX cells may exhibit different responses to ionizing radiation due to their dissimilar epigenetic status. Similar to previous studies, we found that MCF-7/DOX cells harbor much lower levels of global DNA methylation than MCF-7 cells. Furthermore, we found that MCF-7/DOX cells had lower background apoptosis levels and were less responsive to radiation than MCF-7 cells. Decreased radiation responsiveness correlated to significant global DNA hypomethylation in MCF-7/DOX cells. Here, for the first time, we show that the radiation resistance of MCF-7/DOX cells can be reversed by an epigenetic treatment - the application of methyl-donor SAM. SAM-mediated reversal of DNA methylation led to elevated radiation sensitivity in MCF-7/DOX cells. Contrarily, application of SAM on the radiation sensitive and higher methylated MCF-7 cells resulted in a decrease in their radiation responsiveness. This data suggests that a fine balance of DNA methylation is needed to insure proper radiation and drug responsiveness.

MicroRNA-203 Modulates the Radiation Sensitivity of Human Malignant Glioma Cells

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Chang, Ji Hyun; Hwang, Yeo Hyun; Lee, David J.; Kim, Dan Hyo; Park, Ji Min; Wu, Hong-Gyun; Kim, In Ah

2016-01-01

Purpose: We investigated whether miR-203 could modulate the radiation sensitivity of glioblastoma (GBM) cells and which target gene(s) could be involved. Methods and Materials: Three human malignant glioma (MG) cell lines and normal human astrocytes were transfected with control microRNA, pre-miR-203, or antisense miR-203. Real-time PCR (RT-PCR), clonogenic assays, immunofluorescence, and invasion/migration assays were performed. To predict the target(s), bioinformatics analyses using microRNA target databases were performed. Results: Overexpression of miR-203 increased the radiation sensitivity of all 3 human MG cell lines and prolonged radiation-induced γ-H2AX foci formation. Bioinformatics analyses suggested that miR-203 could be involved in post-transcriptional control of DNA repair, PI3K/AKT, SRC, and JAK/STAT3 and the vascular signaling pathway. Western blot analysis validated the fact that miR-203 downregulated ATM, RAD51, SRC, PLD2, PI3K-AKT, JAK-STAT3, VEGF, HIF-1α, and MMP2. Overexpression of miR-203 inhibited invasion and migration potentials, downregulated SLUG and Vimentin, and upregulated Claudin-1 and ZO1. Conclusions: These data demonstrate that miR-203 potentially controls DNA damage repair via the PI3K/AKT and JAK/STAT3 pathways and may collectively contribute to the modulation of radiation sensitivity in MG cells by inhibiting DNA damage repair, prosurvival signaling, and epithelium-mesenchyme transition. Taken together, these findings demonstrate that miR-203 could be a target for overcoming the radiation resistance of GBM.

MicroRNA-203 Modulates the Radiation Sensitivity of Human Malignant Glioma Cells

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Chang, Ji Hyun [Department of Radiation Oncology, Graduate School of Medicine, Seoul National University, Seoul (Korea, Republic of); Hwang, Yeo Hyun; Lee, David J.; Kim, Dan Hyo; Park, Ji Min [Medical Science Research Institute, Seoul National University Bundang Hospital, Kyeonggido (Korea, Republic of); Wu, Hong-Gyun [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, Kyeonggido (Korea, Republic of); Cancer Research Institute, Seoul National University, Seoul (Korea, Republic of)

2016-02-01

Purpose: We investigated whether miR-203 could modulate the radiation sensitivity of glioblastoma (GBM) cells and which target gene(s) could be involved. Methods and Materials: Three human malignant glioma (MG) cell lines and normal human astrocytes were transfected with control microRNA, pre-miR-203, or antisense miR-203. Real-time PCR (RT-PCR), clonogenic assays, immunofluorescence, and invasion/migration assays were performed. To predict the target(s), bioinformatics analyses using microRNA target databases were performed. Results: Overexpression of miR-203 increased the radiation sensitivity of all 3 human MG cell lines and prolonged radiation-induced γ-H2AX foci formation. Bioinformatics analyses suggested that miR-203 could be involved in post-transcriptional control of DNA repair, PI3K/AKT, SRC, and JAK/STAT3 and the vascular signaling pathway. Western blot analysis validated the fact that miR-203 downregulated ATM, RAD51, SRC, PLD2, PI3K-AKT, JAK-STAT3, VEGF, HIF-1α, and MMP2. Overexpression of miR-203 inhibited invasion and migration potentials, downregulated SLUG and Vimentin, and upregulated Claudin-1 and ZO1. Conclusions: These data demonstrate that miR-203 potentially controls DNA damage repair via the PI3K/AKT and JAK/STAT3 pathways and may collectively contribute to the modulation of radiation sensitivity in MG cells by inhibiting DNA damage repair, prosurvival signaling, and epithelium-mesenchyme transition. Taken together, these findings demonstrate that miR-203 could be a target for overcoming the radiation resistance of GBM.

Mutant p53 transfection of astrocytic cells results in altered cell cycle control, radiation sensitivity, and tumorigenicity

International Nuclear Information System (INIS)

Kanady, Kirk E.; Mei Su; Proulx, Gary; Malkin, David M.; Pardo, Francisco S.

1995-01-01

Introduction: Alterations in the p53 tumor suppressor gene are one of the most frequent genetic alterations in malignant gliomas. An understanding of the molecular genetic events leading to glial tumor progression would aid in designing therapeutic vectors for controlling these challenging tumor types. We investigated whether mutations in coding exons of the p53 gene result in functional changes altering cell cycle 'checkpoint' control and the intrinsic radiation sensitivity of glial cells. Methods: An astrocytic cell line was derived from a low grade astrocytoma and characterized to be of human karyotype and GFAP positivity. Additionally, the cellular population has never formed tumors in immune-deficient mice. At early passage ( 2 as parameters. Cell kinetic analyses after 2, 5, and 10 Gy of ionizing radiation were conducted using propidium iodide FACS analyses. Results: Overall levels of p53 expression were increased 5-10 fold in the transfected cellular populations. Astrocytic cellular populations transfected with mutant p53 revealed a statistically significant increase in levels of resistance to ionizing radiation in vitro (2-tailed test, SF2, MID). Astrocytic cellular populations transfected with mutant p53, unlike the parental cells, were tumorigenic in SCID mice. Cell kinetic analyses indicated that the untransfected cell line demonstrated dose dependent G1 and G2 arrests. Following transfection, however, the resultant cellular population demonstrated a predominant G2 arrest. Conclusions: Astrocytic cellular populations derived from low grade astrocytomas, are relatively radiation sensitive, non-tumorigenic, and have intact cell cycle ''checkpoints.'' Cellular populations resulting upon transfection of parental cells with a dominant negative p53 mutation, are relatively radiation resistant, when compared to both parental and mock-transfected cells. Transfected cells demonstrate abnormalities of cell cycle control at the G1/S checkpoint, increases in levels

Toxic clinical hypoxic radiation sensitizers plus radiation-induced toxicity

International Nuclear Information System (INIS)

Richmond, R.C.

1984-01-01

The operational definition espoused twelve years ago that clinical hypoxic radiation sensitizers should be nontoxic interferes with the recognition and research of useful radiation sensitizers. Eight years ago the toxic antitumor drug cis-dichlorodiammineplatinum(II) was reported to be a hypoxic radiation sensitizer and the selective antitumor action of this drug was stressed as potentially creating tumor-targeted radiation sensitization. This rationale of oxidative antitumor drugs as toxic and targeted clinical sensitizers is useful, and has led to the study reported here. The antitumor drug cis-(1,1-cyclobutane-dicarboxylato)diammineplatinum(II), or JM-8, is being tested in clinical trials. Cells of S. typhimurium in PBS in the presence of 0.2mM JM-8 are found to be sensitized to irradiation under hypoxic, but not oxic, conditions. JM-8 is nontoxic to bacteria at this concentration, but upon irradiation the JM-8 solution becomes highly toxic. This radiation induced toxicity of JM-8 preferentially develops from hypoxic solution, and thus contributes to the rationale of hypoxic tumor cell destruction

Resveratrol sensitization of DU145 prostate cancer cells to ionizing radiation is associated to ceramide increase.

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Scarlatti, Francesca; Sala, Giusy; Ricci, Clara; Maioli, Claudio; Milani, Franco; Minella, Marco; Botturi, Marco; Ghidoni, Riccardo

2007-08-08

Radiotherapy is an established therapeutic modality for prostate cancer. Since it is well known that radiotherapy is limited due to its severe toxicity towards normal cells at high dose and minimal effect at low dose, the search for biological compounds that increase the sensitivity of tumors cells to radiation may improve the efficacy of therapy. Resveratrol, a natural antioxidant, was shown to inhibit carcinogenesis in animal models, and to block the process of tumor initiation and progression. The purpose of this study was to examine whether or not resveratrol can sensitize DU145, an androgen-independent human prostate cancer cell line, to ionizing radiation. We report here that DU145 cells are resistant to ionizing radiation-induced cell death, but pretreatment with resveratrol significantly enhances cell death. Resveratrol acts synergistically with ionizing radiation to inhibit cell survival in vitro. Resveratrol also potentiates ionizing radiation-induced ceramide accumulation, by promoting its de novo biosynthesis. This confirms ceramide as an effective mediator of the anticancer potential induced by resveratrol.

Role of p53 status in radiation sensitivity and cell cycle progression

International Nuclear Information System (INIS)

Zellars, Richard C.; Loney, Tania; Schott, Ann F.; Davis, Mary A.; Maybaum, Jonathan; Clarke, Michael F.; Lawrence, Theodore S.

1995-01-01

Purpose: Although p53 function plays a major role in G1 arrest after radiation, the influence of p53 status on progress through other phases of the cell cycle and on radiation sensitivity of human tumors is less clear. We investigated these issues using cells with a conditional expression system for wild type p53. Methods: A temperature sensitive murine wild type p53 plasmid was used (Ginsberg D, et al: Mol. Cell.Biol . 11:582, 1991). At the permissive temperature (32 deg. C), this plasmid produces a protein which assumes a conformation that exhibits wild type p53 function. However, when cells are cultured at 38 deg. C, this protein assumes an inactive conformation. HT29 human colon cancer cells (which are p53 mutant) were transduced with this plasmid (designated PEP A and PEP G cells) or a control vector (designated CCH1 cells) using electroporation and Geneticin selection. The presence of murine p53 transcript in the PEP cells was confirmed by Northern analysis. Results: Cells were cultured under 3 conditions: 1) 38 deg. C at all times; 2) 32 deg. C for 24 hours prior to irradiation and 3) 32 deg. C for 24 hours after irradiation. We found that culturing under permissive temperatures produced a small decrease in surviving fraction in the PEP clones (0.61 ± 0.10 and 0.64 ± 0.07, for PEP A and G, respectively) but not the CCH1 controls (1.14 ± 0.15). PEP cells tended to be more radiosensitive than CCH1 cells (even under non-permissive conditions) and demonstrated a trend towards increased radiosensitivity under both Conditions 2 and 3. In addition, flow cytometry revealed that a 24 hour exposure to permissive conditions increased the fraction of cells in G1 slightly and in G2/M substantially. S phase was almost absent. Conclusion: Restoration of p53 function in HT29 human colon cancer cells using this temperature sensitive system produced increased cytotoxicity and radiation sensitivity as well as cell cycle redistribution. It will be important to assess the

Study of radiation sensitization of artesunate on human HeLa cells of cervical cancer

International Nuclear Information System (INIS)

Ji Rong; Cao Jianping; Chen Xialin; Zhu Wei; Jiang Qing; Pan Chunyan; Zhou Yuanyuan; Feng Yang; Peng Xiaomei; Liu Yang; Fan Saijun

2010-01-01

Objective: To investigate the radiosensitizing effects of artesunate on human HeLa cells of cervical cancer in vitro. Methods: Hela cells irradiated with 60 Co γ-rays. The dose rate was 0.635 Gy/min and the radiation dose was 0, 1, 2, 4, 6 Gy, respectively. The anti-proliferation activities of artesunate on HeLa cells were evaluated with MTT assay, to determine the most appropriate drug concentration. The effect of radiosensitivity was observed by using clonogenic assay. The single-hit multi-target model was used to plot the HeLa cell's dose-survival curve, to calculate mean lethal dose, quasi-threshold dose and sensitization enhancement rate, and to evaluate its radiosensitization effect. The apoptosis was analyzed with flow cytometry (FCM) to further test the radiation sensitization of artesunate on HeLa cells. Results: The inhibition of artesunate on HeLa cells increased with concentration. In radiation group, the cell cloning efficiency were 91.67%, 82.02%, 58.06%, 25.01%, respectively, and in artesunate (2.0 μmol/L) + radiation group, the cell cloning efficiency were 74.93%, 60.53%, 22.38%, 5.05%. In radiation group and artesunate (2.0 μmol/L) + radiation group, the mean lethal dose (D 0 ) was 2.95 and 2.07 Gy, respectively, while the qusai-threshold dose (D q ) were 2.01 and 1.24 Gy, respectively, and SER was 1.43. Compared with 2 and 6 Gy radiation group, the apoptosis rate of drug + radiation group increased from 12.26%, 40.08% to 22.71%, 59.92. Conclusions: The inhibiting effect of artesunate on HeLa cells is concentration-dependent. Artesunate has radiosensitizing effect on HeLa cells in vitro. (authors)

Autophagic cell death induced by reactive oxygen species is involved in hyperthermic sensitization to ionizing radiation in human hepatocellular carcinoma cells.

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Yuan, Guang-Jin; Deng, Jun-Jian; Cao, De-Dong; Shi, Lei; Chen, Xin; Lei, Jin-Ju; Xu, Xi-Ming

2017-08-14

To investigate whether autophagic cell death is involved in hyperthermic sensitization to ionizing radiation in human hepatocellular carcinoma cells, and to explore the underlying mechanism. Human hepatocellular carcinoma cells were treated with hyperthermia and ionizing radiation. MTT and clonogenic assays were performed to determine cell survival. Cell autophagy was detected using acridine orange staining and flow cytometric analysis, and the expression of autophagy-associated proteins, LC3 and p62, was determined by Western blot analysis. Intracellular reactive oxygen species (ROS) were quantified using the fluorescent probe DCFH-DA. Treatment with hyperthermia and ionizing radiation significantly decreased cell viability and surviving fraction as compared with hyperthermia or ionizing radiation alone. Cell autophagy was significantly increased after ionizing radiation combined with hyperthermia treatment, as evidenced by increased formation of acidic vesicular organelles, increased expression of LC3II and decreased expression of p62. Intracellular ROS were also increased after combined treatment with hyperthermia and ionizing radiation. Pretreatment with N-acetylcysteine, an ROS scavenger, markedly inhibited the cytotoxicity and cell autophagy induced by hyperthermia and ionizing radiation. Autophagic cell death is involved in hyperthermic sensitization of cancer cells to ionizing radiation, and its induction may be due to the increased intracellular ROS.

Radiation sensitization by dihydroartemisinin on human HeLa cells of cervical cancer

International Nuclear Information System (INIS)

Chen Xialin; Cao Jianping; Ji Rong; Zhu Wei; Liu Yang; Gong Xiaomei; Tang Yan; Pan Chunyan; Fan Saijun

2009-01-01

Objective: To investigate the radiosensitizing effects of dihydroartemisinin (DHA) on human HeLa cells of cervical cancer irradiated by X rays. Methods: Cell growth kinetics was determined using MTF assay. Cell survival was analyzed by elonogenic assay. The change of cell cycle and apeptosis was measured by flow cytometry. Results: Dihydroartemisinin inhibited the growth of HeLa cells of human cervical cancer and showed a dose-dependent and time-dependent manner. Dihydroartemisinin (20 μmol/L) showed the radiosensitizing effects on HeLa cells, and the sensitizing enhancement ratio (SER) was 1.47. Dihydroartemisinin abrogated radiation-induced G 2 arrest of the tested HeLa cells, the G 2 ratio of medicine + radiation group dechned from 73.58% to 48.31%. Dihydroartemisinin enhanced the apoptosis of HeLa cells by X-irradiation, the apoptosis rates of medicine + radiation group significantly increased from 29.46%, 48.04%, 70.21% to 45.79%, 66.36% and 79.58%, respectively for 2, 4 and 6 Gy. Conclusions: Dihydroartemisinin could increase the radiosensitivity of HeLa cells of human cervical cancer. Abrogation of radiation-induced C 2 arrest could be part of the mechanism. (authors)

The sensitivity of human mesenchymal stem cells to ionizing radiation

International Nuclear Information System (INIS)

Chen, M.-F.; Lin, C.-T.; Chen, W.-C.; Yang, C.-T.; Chen, C.-C.; Liao, S.-K.; Liu, J.M.; Lu, C.-H.; Lee, K.-D.

2006-01-01

Purpose: Recent studies have shown that mesenchymal stem cells (MSCs) obtained from bone marrow transplantation patients originate from the host. This clinical observation suggests that MSCs in their niches could be resistant to irradiation. However, the biologic responses of bone marrow MSCs to irradiation have rarely been described in the literature. Methods and Materials: In this study, human bone marrow-derived, clonally expanded MSCs were used to investigate their sensitivity to irradiation in vitro, and the cellular mechanisms that may facilitate resistance to irradiation. The human lung cancer cell line A549 and the breast cancer cell line HCC1937 were used as controls for radiosensitivity; the former line has been shown to be radioresistant and the latter radiosensitive. We then examined their in vitro biologic changes and sensitivities to radiation therapy. Results: Our results suggest that MSCs are characterized as resistant to irradiation. Several cellular mechanisms were demonstrated that may facilitate resistance to irradiation: ATM protein phosphorylation, activation of cell-cycle checkpoints, double-strand break repair by homologous recombination and nonhomologous end joining (NHEJ), and the antioxidant capacity for scavenging reactive oxygen species. Conclusions: As demonstrated, MSCs possess a better antioxidant reactive oxygen species-scavenging capacity and active double-strand break repair to facilitate their radioresistance. These findings provide a better understanding of radiation-induced biologic responses in MSCs and may lead to the development of better strategies for stem cell treatment and cancer therapy

Gene targeting associated with the radiation sensitivity in squamous cell carcinoma by using microarray analysis

International Nuclear Information System (INIS)

Nimura, Yoshinori; Kumagai, Ken; Kouzu, Yoshinao; Higo, Morihiro; Kato, Yoshikuni; Seki, Naohiko; Yamada, Shigeru

2005-01-01

In order to identify a set of genes related to radiation sensitivity of squamous cell carcinoma (SCC) and establish a predictive method, we compared expression profiles of radio-sensitive/radio-resistant SCC cell lines, using the in-house cDNA microarray consisting of 2,201 human genes derived from full-length enriched SCC cDNA libraries and the Human oligo chip 30 K (Hitachi Software Engineering). Surviving fractions (SF) after irradiation of heavy iron were calculated by colony formation assay. Three pairs (TE2-TE13, YES5-YES6, and HSC3-HSC2), sensitive (SF1 0.6), were selected for the microarray analysis. The results of cDNA microarray analysis showed that 20 genes in resistant cell lines and 5 genes in sensitive cell lines were up regulated more than 1.5-fold compared with sensitive and resistant cell lines respectively. Fourteen out of 25 genes were confirmed the gene expression profiles by real-time polymerase chain reaction (PCR). Twenty-seven genes identified by Human oligo chip 30 K are candidate for the markers to distinguish radio-sensitive from radio-resistant. These results suggest that the isolated 27 genes are the candidates that might be used as specific molecular markers to predict radiation sensitivity. (author)

Role of the NRP-1-mediated VEGFR2-independent pathway on radiation sensitivity of non-small cell lung cancer cells.

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Hu, Chenxi; Zhu, Panrong; Xia, Youyou; Hui, Kaiyuan; Wang, Mei; Jiang, Xiaodong

2018-07-01

To determine if inhibiting neuropilin-1 (NRP-1) affects the radiosensitivity of NSCLC cells through a vascular endothelial growth factor receptor 2 (VEGFR2)-independent pathway, and to assess the underlying mechanisms. The expression of VEGFR2, NRP-1, related signaling molecules, abelson murine leukemia viral oncogene homolog 1 (ABL-1), and RAD51 were determined by RT-PCR and Western blotting, respectively. Radiosensitivity was assessed using the colony-forming assay, and the cell apoptosis were analyzed by flow cytometry. We selected two cell lines with high expression levels of VEGFR2, including Calu-1 cells that have high NRP-1 expression, and H358 cells that have low NRP-1 expression. Upon inhibition of p-VEGFR2 by apatinib in Calu-1 cells, the expression of NRP-1 protein and other related proteins in the pathway was still high. Upon NRP-1 siRNA treatment, the expression of both NRP-1 and RAD51 decreased (p cells treated with NRP-1 siRNA exhibited significantly higher apoptosis and radiation sensitivity in radiation therapy compared to Calu-1 cells treated with apatinib alone (p cells with NRP-1 overexpression was similar to the control group regardless of VEGFR2 inhibition. We demonstrated that when VEGFR2 was inhibited, NRP-1 appeared to regulate RAD51 expression through the VEGFR2-independent ABL-1 pathway, consequently regulating radiation sensitivity. In addition, the combined inhibition of VEGFR2 and NRP-1 appears to sensitize cancer cells to radiation.

In vitro radiation and chemotherapy sensitivity of established cell lines of human small cell lung cancer and its large cell morphological variants

International Nuclear Information System (INIS)

Carney, D.N.; Mitchell, J.B.; Kinsella, T.J.

1983-01-01

The in vitro response to radiation and chemotherapeutic drugs of cell lines established from 7 patients with small cell (SC) lung cancer were tested using a soft agarose clonogenic assay. Five cell lines retained the typical morphological and biochemical amine precursor uptake decarboxylation characteristics of SC, while two cell lines had undergone ''transformation'' to large cell (LC) morphological variants with loss of amine precursor uptake decarboxylation cell characteristics of SC. The radiation survival curves for the SC lines were characterized by D0 values ranging from 51 to 140 rads and extrapolation values (n) ranging from 1.0 to 3.3. While the D0 values of the radiation survival curves of the LC variants were similar (91 and 80 rads), the extrapolation values were 5.6 and 11.1 In vitro chemosensitivity testing of the cell lines revealed an excellent correlation between prior treatment status of the patient and in vitro sensitivity or resistance. No correlation was observed between in vitro chemosensitivity and radiation response. These data suggest that transformation of SC to LC with loss of amine precursor uptake and decarboxylation characteristics is associated with a marked increase in radiation resistance (n) in vitro. The observation of a 2- to 5-fold increase in survival of the LC compared to the SC lines following 200 rads suggests that the use of larger daily radiation fractions and/or radiation-sensitizing drugs might lead to a significantly greater clinical response in patients with LC morphology. This clinical approach may have a major impact on patient response and survival

Origin of the effects of cell cycle age on radiation sensitivity

International Nuclear Information System (INIS)

Nelson, J.M.; Braby, L.A.; Metting, N.F.; Roesch, W.C.

1987-01-01

The observed differences in radiation sensitivity as a function of cell age could reflect either differences in cellular capacity to remove different types of damage, or differences in damage production. The authors used centrifugal elutriation methods to produce enriched populations of G/sub 1/-, S-, and G/sub 2/-phase cells from stationary phase CHO cultures. Recognizing the imperfect correlation between cell age and cross-sectional area (the criterion upon which the separation process is based) flow-cytometric methods were used to measure cellular DNA content and determine cell age distributions. Split-dose repair kinetics were then determined for cells in different phases of the cycle. The authors find no striking differences in total repair, indicating that damage is removed at generally the same rate and with essentially the same efficiency, throughout the cell cycle. This suggests that changes in the production of damage are likely responsible for the change in sensitivity

Histone Deacetylase Inhibitor Induced Radiation Sensitization Effects on Human Cancer Cells after Photon and Hadron Radiation Exposure

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Ariungerel Gerelchuluun

2018-02-01

Full Text Available Suberoylanilide hydroxamic acid (SAHA is a histone deacetylase inhibitor, which has been widely utilized throughout the cancer research field. SAHA-induced radiosensitization in normal human fibroblasts AG1522 and lung carcinoma cells A549 were evaluated with a combination of γ-rays, proton, and carbon ion exposure. Growth delay was observed in both cell lines during SAHA treatment; 2 μM SAHA treatment decreased clonogenicity and induced cell cycle block in G1 phase but 0.2 μM SAHA treatment did not show either of them. Low LET (Linear Energy Transfer irradiated A549 cells showed radiosensitization effects on cell killing in cycling and G1 phase with 0.2 or 2 μM SAHA pretreatment. In contrast, minimal sensitization was observed in normal human cells after low and high LET radiation exposure. The potentially lethal damage repair was not affected by SAHA treatment. SAHA treatment reduced the rate of γ-H2AX foci disappearance and suppressed RAD51 and RPA (Replication Protein A focus formation. Suppression of DNA double strand break repair by SAHA did not result in the differences of SAHA-induced radiosensitization between human cancer cells and normal cells. In conclusion, our results suggest SAHA treatment will sensitize cancer cells to low and high LET radiation with minimum effects to normal cells.

In vivo sensitivity of the embryonic and adult neural stem cell compartments to low-dose radiation.

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Barazzuol, Lara; Jeggo, Penny A

2016-08-01

The embryonic brain is radiation-sensitive, with cognitive deficits being observed after exposure to low radiation doses. Exposure of neonates to radiation can cause intracranial carcinogenesis. To gain insight into the basis underlying these outcomes, we examined the response of the embryonic, neonatal and adult brain to low-dose radiation, focusing on the neural stem cell compartments. This review summarizes our recent findings. At E13.5-14.5 the embryonic neocortex encompasses rapidly proliferating stem and progenitor cells. Exploiting mice with a hypomorphic mutation in DNA ligase IV (Lig4(Y288C) ), we found a high level of DNA double-strand breaks (DSBs) at E14.5, which we attribute to the rapid proliferation. We observed endogenous apoptosis in Lig4(Y288C) embryos and in WT embryos following exposure to low radiation doses. An examination of DSB levels and apoptosis in adult neural stem cell compartments, the subventricular zone (SVZ) and the subgranular zone (SGZ) revealed low DSB levels in Lig4(Y288C) mice, comparable with the levels in differentiated neuronal tissues. We conclude that the adult SVZ does not incur high levels of DNA breakage, but sensitively activates apoptosis; apoptosis was less sensitively activated in the SGZ, and differentiated neuronal tissues did not activate apoptosis. P5/P15 mice showed intermediate DSB levels, suggesting that DSBs generated in the embryo can be transmitted to neonates and undergo slow repair. Interestingly, this analysis revealed a stage of high endogenous apoptosis in the neonatal SVZ. Collectively, these studies reveal that the adult neural stem cell compartment, like the embryonic counterpart, can sensitively activate apoptosis. © The Author 2016. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

LyGDI expression in HeLa cells increased its sensitivity to radiation-induced apoptosis

International Nuclear Information System (INIS)

Zhou Xinwen; Xu Yaxiang

2006-01-01

Objective: In order to confirm whether LyGDI has apoptotic signal transduction function and can increase the apoptotic rate of radiation-induced cell death, the lyGDI and mutant D19lyGDI gene, which constructed with the pCDNA3. 1 His A, were transfected into no-endogenous lyGDI HeLa cells. Methods Transient expressions of lyGDI and D19lyGDI in HeLa cells were analyzed by Western blot using anti-mono antibody of LyGDI and Xpress tag. Cell apoptosis was assayed with Annexin V-FITC apoptosis kit. To select stable clone, the transferred HeLa cells had been maintained in G418 medium for 3 weeks, then a cell line, which stably expressed LyGDI and mutant D19lyGDI, was selected. The selected cell line was irradiated with 12 Gy 60 Co y-rays. Caspase-3 activity of the cells was determined by Western blot and cell viability by clone-forming assay after 48 hours post-irradiation culture. Results: Western blot and Annexin V-FITC apoptotic analysis revealed that lyGDI and D19lyGDI transient expressions in HeLa cells induced apoptosis; Caspase-3 activity measurement and clone-forming assay showed that lyGDI increased sensitivity to radiation-induced cell apoptosis. Conclusions: lyGDI performs function in apoptosis signal transduction, its expression in HeLa cells can increase the sensitivity to radiation-induced cell apoptosis. (authors)

Sensitization of ultraviolet radiation damage in bacteria and mammalian cells

International Nuclear Information System (INIS)

Fisher, G.J.; Watts, M.E.; Patel, K.B.; Adams, G.E.

1978-01-01

Bacteria (Serratia marcescens) and mammalian cells (Chinese hamsters V79-379A) were irradiated in monolayers with ultraviolet light at 254 nm or 365 nm in the presence or absence of radiosensitizing drugs. At 254 nm, killing is very efficient (Dsub(37) approximately equal 1 J m -2 exposure, or approximately equal 6 x 10 4 photons absorbed by DNA per bacterium), and sensitizers have no effect. At 365 nm, cells are not killed in buffer, but are inactivated in the presence of nifurpipone or misonidazole. Lethal exposures (approximately equal 5 x 10 3 J m -2 at 10 nM misonidazole) correspond to about 10 7 photons absorbed by sensitizer molecules per bacterium. Toxicity of stable photoproducts of the drugs is not involved, nor is oxygen required. Hence the transient species formed by photo-excitation of radiosensitizer molecules are capable of killing cells in the absence of other types of radiation damage. (author)

Phenylbutyrate Sensitizes Human Glioblastoma Cells Lacking Wild-Type P53 Function to Ionizing Radiation

International Nuclear Information System (INIS)

Lopez, Carlos A.; Feng, Felix Y.; Herman, Joseph M.; Nyati, Mukesh K.; Lawrence, Theodore S.; Ljungman, Mats

2007-01-01

Purpose: Histone deacetylase (HDAC) inhibitors induce growth arrest, differentiation, and apoptosis in cancer cells. Phenylbutyrate (PB) is a HDAC inhibitor used clinically for treatment of urea cycle disorders. Because of its low cytotoxicity, cerebrospinal fluid penetration, and high oral bioavailability, we investigated PB as a potential radiation sensitizer in human glioblastoma cell lines. Methods and Materials: Four glioblastoma cell lines were selected for this study. Phenylbutyrate was used at a concentration of 2 mM, which is achievable in humans. Western blots were used to assess levels of acetylated histone H3 in tumor cells after treatment with PB. Flow cytometry was used for cell cycle analysis. Clonogenic assays were performed to assess the effect of PB on radiation sensitivity. We used shRNA against p53 to study the role of p53 in radiosensitization. Results: Treatment with PB alone resulted in hyperacetylation of histones, confirmed by Western blot analysis. The PB alone resulted in cytostatic effects in three cell lines. There was no evidence of G 1 arrest, increase in sub-G 1 fraction or p21 protein induction. Clonogenic assays showed radiosensitization in two lines harboring p53 mutations, with enhancement ratios (± SE) of 1.5 (± 0.2) and 1.3 (± 0.1), respectively. There was no radiopotentiating effect in two cell lines with wild-type p53, but knockdown of wild-type p53 resulted in radiosensitization by PB. Conclusions: Phenylbutyrate can produce p21-independent cytostasis, and enhances radiation sensitivity in p53 mutant human glioblastoma cells in vitro. This suggests the potential application of combined PB and radiotherapy in glioblastoma harboring mutant p53

Age and radiation sensitivity of rat mammary clonogenic cells

International Nuclear Information System (INIS)

Shimada, Yoshiya; Yasukawa-Barnes, J.; Kim, R.Y.; Gould, M.N.; Clifton, K.H.

1994-01-01

The relative risk of breast cancer is very high among women who were exposed to ionizing radiation during or before puberty. In the current studies, the surviving fractions of clonogenic mammary cells of groups of virgin rats were estimated after single exposures to 137 Cs γ rays at intervals from 1 to 12 weeks after birth. The radiosensitivity of clonogens from prepubertal rats was high and changed with the onset of puberty at between 4 and 6 weeks of age. By this time, the increase in the size of the clonogenic cell subpopulation was slowing and differentiation of terminal mammary end buds and alveolar structures was occurring. Analysis of the relationship of clonogen survival and radiation dose according to the α/β model showed that the exponential αD term predominated at the second and fourth weeks of age. By the eighth week of age, the βD 2 term had come to predominate and the survival curve had a pronounced initial convex shoulder. Further experiments are required to determine whether there is an association between the high sensitivity of the prepubertal and pubertal mammary clonogens to radiation killing and a high susceptibility to radiogenic initiation of cancer. 24 refs., 4 figs., 1 tab

Sensitivity of mitochondria of the mouse liver cells to radiation

Energy Technology Data Exchange (ETDEWEB)

Shima, A [Tokyo Univ. (Japan). Faculty of Science

1974-06-01

In order to study the sensitivity of mitochondria (Mt) of the liver cells to radiation, 0.4 mg of riboflavine (RF) was intraperitoneally injected into mice which had been fed RF deficient food for 13 weeks. Three hours later 400 R of X-ray (190 KVP, 25 mA, 0.5 mmCu, 0.5 mmAl filter, FSD 61.5 cm, and HVL 0.80 mmCu) were irradiated to the whole body, and giant Mt of the liver cells were observed. When the liver cells were observed 24 hours after injection, neither giant Mt nor mitotic findings of Mt were found. All Mt observed were small (1.2 ..mu..), although mice received 400 R of X-ray.

Relationship between intrinsic radiation sensitivity and metastatic potential

International Nuclear Information System (INIS)

Lewis, Anne M.; Mei, Su; Doty, Jay; Chen Yi; Pardo, Francisco S.

1996-01-01

Purpose: Prior studies emphasized genetic modulation of tumorigenicity, and experimental metastatic potential in cells transfected with oncogenes. Whether the intrinsic radiation sensitivity of cells might correlate with parallel changes in metastatic potential is unknown. Methods and Materials: Rat embryo cells (REC) were transfected with the following oncogenes, and where appropriate, with corresponding selection markers: pCMV neopEJ6.6ras, pEJ6.6ras/v-myc, pE1a, and pEJ6-.6ras/E1a. Individual transfectant clones and corresponding pooled cellular populations were propagated in selective medium. In vitro cellular radiation sensitivity was determined via clonogenic assays, a minimum of three, by standard techniques and individual SF 2 and MID parameters determined. Tumorigenicity was defined as the number of tumors forming following the injection of 1 x 10 5 - 1 x 10 6 cells into the axillary pouch of three different strains of immune-deficient mice. Animals were killed once resultant tumors reached a maximum size of 1.5-2.0 cm in maximum diameter. For determination of experimental metastatic potential, between 1 x 10 5 -1 x 10 6 cells were injected into the tail veins of litter-matched sibling mice in parallel to the tumorigenicity studies. Results: Radiobiologic studies indicate similar levels of radiation sensitivity among REC, mock-transfected REC, E1a, and combined E1a/ras transfectants. pEJ6.6ras, and combined ras/myc transfected pooled cellular populations demonstrated increases in radiation resistance when compared to the pooled radiobiologic data from untransfected and mock-transfected corresponding pooled cellular populations (p 2 , MID). Rat embryo cells, E1a, and mock-transfectants were relatively radiation sensitive and nontumorigenic. pE1a/ras was tumorigenic but demonstrated relatively low experimental metastatic potential. Ras, and ras/myc transfectants, demonstrated similar levels of experimental metastatic potential on lung colonization assays

In vivo sensitivity of the embryonic and adult neural stem cell compartments to low-dose radiation

International Nuclear Information System (INIS)

Barazzuol, Lara; Jeggo, Penny A.

2016-01-01

The embryonic brain is radiation-sensitive, with cognitive deficits being observed after exposure to low radiation doses. Exposure of neonates to radiation can cause intracranial carcinogenesis. To gain insight into the basis underlying these outcomes, we examined the response of the embryonic, neonatal and adult brain to low-dose radiation, focusing on the neural stem cell compartments. This review summarizes our recent findings. At E13.5–14.5 the embryonic neocortex encompasses rapidly proliferating stem and progenitor cells. Exploiting mice with a hypomorphic mutation in DNA ligase IV (Lig4 Y288C ), we found a high level of DNA double-strand breaks (DSBs) at E14.5, which we attribute to the rapid proliferation. We observed endogenous apoptosis in Lig4 Y288C embryos and in WT embryos following exposure to low radiation doses. An examination of DSB levels and apoptosis in adult neural stem cell compartments, the subventricular zone (SVZ) and the subgranular zone (SGZ) revealed low DSB levels in Lig4 Y288C mice, comparable with the levels in differentiated neuronal tissues. We conclude that the adult SVZ does not incur high levels of DNA breakage, but sensitively activates apoptosis; apoptosis was less sensitively activated in the SGZ, and differentiated neuronal tissues did not activate apoptosis. P5/P15 mice showed intermediate DSB levels, suggesting that DSBs generated in the embryo can be transmitted to neonates and undergo slow repair. Interestingly, this analysis revealed a stage of high endogenous apoptosis in the neonatal SVZ. Collectively, these studies reveal that the adult neural stem cell compartment, like the embryonic counterpart, can sensitively activate apoptosis

Parg deficiency confers radio-sensitization through enhanced cell death in mouse ES cells exposed to various forms of ionizing radiation

Energy Technology Data Exchange (ETDEWEB)

Shirai, Hidenori; Fujimori, Hiroaki [Division of Genome Stability Research, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045 (Japan); Gunji, Akemi [Biochemistry Division, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045 (Japan); Maeda, Daisuke [Biochemistry Division, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045 (Japan); ADP-Ribosylation in Oncology Project, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045 (Japan); Hirai, Takahisa [Division of Genome Stability Research, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045 (Japan); Department of Radiation Oncology, Juntendo University Faculty of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421 (Japan); Poetsch, Anna R. [ADP-Ribosylation in Oncology Project, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045 (Japan); Harada, Hiromi [Division of Genome Stability Research, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045 (Japan); Yoshida, Tomoko [Biochemistry Division, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045 (Japan); Kyoritsu College of Pharmacy, 1-5-30 Shibakoen, Minatoku, Tokyo 105-8512 (Japan); Sasai, Keisuke [Department of Radiation Oncology, Juntendo University Faculty of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421 (Japan); Okayasu, Ryuichi [International Open Laboratory, National Institute of Radiological Science, 4-9-1 Anagawa, Inage, Chiba 263-8555 (Japan); Masutani, Mitsuko, E-mail: mmasutan@ncc.go.jp [Division of Genome Stability Research, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045 (Japan); Biochemistry Division, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045 (Japan); ADP-Ribosylation in Oncology Project, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045 (Japan)

2013-05-24

Highlights: •Parg{sup −/−} ES cells were more sensitive to γ-irradiation than Parp-1{sup −/−} ES cells. •Parg{sup −/−} cells were more sensitive to carbon-ion irradiation than Parp-1{sup −/−} cells. •Parg{sup −/−} cells showed defects in DSB repair after carbon-ion irradiation. •PAR accumulation was enhanced after carbon-ion irradiation compared to γ-irradiation. -- Abstract: Poly(ADP-ribose) glycohydrolase (Parg) is the main enzyme involved in poly(ADP-ribose) degradation. Here, the effects of Parg deficiency on sensitivity to low and high linear-energy-transfer (LET) radiation were investigated in mouse embryonic stem (ES) cells. Mouse Parg{sup −/−} and poly(ADP-ribose) polymerase-1 deficient (Parp-1{sup −/−}) ES cells were used and responses to low and high LET radiation were assessed by clonogenic survival and biochemical and biological analysis methods. Parg{sup −/−} cells were more sensitive to γ-irradiation than Parp-1{sup −/−} cells. Transient accumulation of poly(ADP-ribose) was enhanced in Parg{sup −/−} cells. Augmented levels of phosphorylated H2AX (γ-H2AX) from early phase were observed in Parg{sup −/−} ES cells. The induction level of p53 phophorylation at ser18 was similar in wild-type and Parp-1{sup −/−} cells and apoptotic cell death process was mainly observed in the both genotypes. These results suggested that the enhanced sensitivity of Parg{sup −/−} ES cells to γ-irradiation involved defective repair of DNA double strand breaks. The effects of Parg and Parp-1 deficiency on the ES cell response to carbon-ion irradiation (LET13 and 70 keV/μm) and Fe-ion irradiation (200 keV/μm) were also examined. Parg{sup −/−} cells were more sensitive to LET 70 keV/μm carbon-ion irradiation than Parp-1{sup −/−} cells. Enhanced apoptotic cell death also accompanied augmented levels of γ-H2AX in a biphasic manner peaked at 1 and 24 h. The induction level of p53 phophorylation at ser18 was

Parg deficiency confers radio-sensitization through enhanced cell death in mouse ES cells exposed to various forms of ionizing radiation

International Nuclear Information System (INIS)

Shirai, Hidenori; Fujimori, Hiroaki; Gunji, Akemi; Maeda, Daisuke; Hirai, Takahisa; Poetsch, Anna R.; Harada, Hiromi; Yoshida, Tomoko; Sasai, Keisuke; Okayasu, Ryuichi; Masutani, Mitsuko

2013-01-01

Highlights: •Parg −/− ES cells were more sensitive to γ-irradiation than Parp-1 −/− ES cells. •Parg −/− cells were more sensitive to carbon-ion irradiation than Parp-1 −/− cells. •Parg −/− cells showed defects in DSB repair after carbon-ion irradiation. •PAR accumulation was enhanced after carbon-ion irradiation compared to γ-irradiation. -- Abstract: Poly(ADP-ribose) glycohydrolase (Parg) is the main enzyme involved in poly(ADP-ribose) degradation. Here, the effects of Parg deficiency on sensitivity to low and high linear-energy-transfer (LET) radiation were investigated in mouse embryonic stem (ES) cells. Mouse Parg −/− and poly(ADP-ribose) polymerase-1 deficient (Parp-1 −/− ) ES cells were used and responses to low and high LET radiation were assessed by clonogenic survival and biochemical and biological analysis methods. Parg −/− cells were more sensitive to γ-irradiation than Parp-1 −/− cells. Transient accumulation of poly(ADP-ribose) was enhanced in Parg −/− cells. Augmented levels of phosphorylated H2AX (γ-H2AX) from early phase were observed in Parg −/− ES cells. The induction level of p53 phophorylation at ser18 was similar in wild-type and Parp-1 −/− cells and apoptotic cell death process was mainly observed in the both genotypes. These results suggested that the enhanced sensitivity of Parg −/− ES cells to γ-irradiation involved defective repair of DNA double strand breaks. The effects of Parg and Parp-1 deficiency on the ES cell response to carbon-ion irradiation (LET13 and 70 keV/μm) and Fe-ion irradiation (200 keV/μm) were also examined. Parg −/− cells were more sensitive to LET 70 keV/μm carbon-ion irradiation than Parp-1 −/− cells. Enhanced apoptotic cell death also accompanied augmented levels of γ-H2AX in a biphasic manner peaked at 1 and 24 h. The induction level of p53 phophorylation at ser18 was not different between wild-type and Parg −/− cells. The augmented

Sensitivity to radiation and cycle-active drugs as a function of stem cell compartment repletion

International Nuclear Information System (INIS)

Degowin, R.L.; Gibson, D.P.

1976-01-01

We have studied the sensitivity of normal mouse hemopoietic tissue to radiation and cycle-active drugs in relation to stem cell compartment repletion. Recovery of erythropoiesis in endogenous spleen colonies, blood reticulocytes, and 30-day survivals were determined in mice after an initial large dose of partial-body irradiation. We found that the normal stem cell compartment is more sensitive to cycle-independent modes of therapy, like radiation and cyclophosphamide, than it is to cycle-active agents like cytosine arabinoside and methotrexate. The depleted stem cell compartment exhibits marked sensitivity to cycle-independent agents but less to cycle-active agents, which, however, suppress its recovery more than they do the normal. The overshoot phase of recovery is relatively resistant to either cycle-independent or cycle-active agents. A reticulocytosis following a reticulocytopenia signals the overshoot phase of stem cell compartment recovery and relatively increased resistance. These findings may prove useful in designing chemotherapy regimens and in anticipating marrow recovery in planning for supportive care in patients with neoplastic disease

Comparison of radiation sensitivity for three cell lines as measured by the cloning assay and the micro-nucleus test

NARCIS (Netherlands)

Stap, J.; Aten, J. A.

1990-01-01

The correlation between cell killing and the induction of micro-nuclei was studied for three cell lines after treatment with gamma radiation to investigate whether the frequency of micro-nucleated cells can be used to determine the radiation sensitivity of a cell type. R1 rat rhabdomyosarcoma cells

Development of a model system to study leukotriene-induced modification of radiation sensitivity in mammalian cells

Energy Technology Data Exchange (ETDEWEB)

Walden, Jr, T L; Holahan, Jr, E V; Catravas, G N

1986-01-01

Leukotrienes (LT) are an important class of biological mediators for which no information exists concerning their synthesis following a radiation insult or on their ability to modify cellular response to a subsequent radiation exposure. Results are presented which illustrate that the Chinese hamster lung fibroblast cell line, V79A03, is useful as a model system to study the metabolic fate of leukotrienes and the effect of LT on radiation sensitivity of mammalian cells in vitro. (U.K.).

Caffeine-enhanced survival of radiation-sensitive, repair-deficient Chinese hamster cells

International Nuclear Information System (INIS)

Utsumi, H.; Elkind, M.M.

1983-01-01

A clone of V79 Chinese hamster cells (V79-AL162/S-10) with unique properties has been isolated after a challenge of parental cells (V79-AL162) with 1 mM ouabain. Compared with parental cells, or with other clones isolated after the ouabain challenge, these cells form smaller colonies, are more sensitive to both x rays and fission-spectrum neutrons, and respond atypically to a postirradiation treatment with caffeine. Their enhanced response to x rays results mainly from a large reduction in the shoulder of their survival curve, probably because in late S phase, the most resistant phase in the cell cycle, the survival curve of these cells has a reduced shoulder width. Caffeine, and to a lesser extent theophylline, added to the colony-forming medium immediately after exposure appreciably increases the width of the shoulder of these sensitive cells, whereas caffeine has the opposite effect on the response of normal V79 cells. Thus the unique response of the V79-AL162/S-10 cells to a radiation posttreatment with caffeine (increased survival) results from a net increase in their ability to repair damage that is otherwise lethal; caffeine treatment ordinarly prevents normal V79 cells from repairing damage that is only potentially lethal

Sensitivity of mitochondria of the mouse liver cells to radiation

International Nuclear Information System (INIS)

Shima, Akihiro

1974-01-01

In order to study the sensitivity of mitochondria (Mt) of the liver cells to radiation, 0.4 mg of riboflavine (RF) was intraperitoneally injected into mice which had been fed RF deficient food for 13 weeks. Three hours later 400 R of X-ray (190 KVP, 25 mA, 0.5 mmCu, 0.5 mmAl filter, FSD 61.5 cm, and HVL 0.80 mmCu) were irradiated to the whole body, and giant Mt of the liver cells were observed. When the liver cells were observed 24 hours after injection, neither giant Mt nor mitotic findings of Mt were found. All Mt observed were small (1.2 μ), although mice received 400 R of X-ray. (Serizawa, K.)

Investigation of the modifying effects of vitamin A and hypoxic cell sensitizers in radiation carcinogenesis in mice

International Nuclear Information System (INIS)

Mian, T.A.

1982-01-01

The effect of vitamin A (retinyl acetate) and three hypoxic cell sensitizers (metronidazole, misonidazole and desmethylmisonidazole) on lung tumor development in strain A mice exposed to radiation was assessed. In experiments involving vitamin A, two groups of mice were fed a low vitamin A diet (< 100 IU/100g diet) while the two other groups were fed a high vitamin A diet (800 IU/100 g diet). After two weeks one group maintained on the high vitamin A diet and one group maintained on the low vitamin A diet were given an acute dose of 500 rad of gamma radiation to the thoracic region. Mice were killed, their lungs were removed and the number of surface adenomas were counted. There was a significant increase in the number of mice bearing lung tumors and the mean number of lung tumors per mouse in the irradiated group maintained on the high vitamin A diet at 40 weeks post irradiation as compared to the irradiated group maintained on a low vitamin A diet. In the other experiment two dose levels of the hypoxic cell sensitizers, 0.2 mg/g and 0.6 mg/g, were used either alone or in combination with 900 rad of gamma radiation in a fractionated dose schedule of twice a week for three weeks. In the groups of mice which received hypoxic cell sensitizers only, the prevalence and the mean number of lung tumors per mouse were somewhat increased in the higher dose group (0.6 mg/g) of misonidazole but was not significantly different from the control animals in the other two sensitizer groups. The combination of hypoxic cell sensitizer and radiation did not show any significant enhancement of lung tumor response when compared with the group which received radiation only. The dose of radiation used in this study significantly enhanced lung tumor formation in mice when compared with the control group

In vivo radiation sensitivity of glioblastoma multiforme

International Nuclear Information System (INIS)

Taghian, Alphonse; Freeman, Jill; Suit, Herman; DuBois, Willem; Budach, Wilfried; Baumann, Michael

1995-01-01

Purpose: Human glioblastoma (GBM) is one of the most resistant tumors to radiation. In previous reports, we have demonstrated a wide range of radiation sensitivity of GBM in vitro; that is, SF 2 values of 0.2 to 0.8. The great sensitivity of some of the cell lines is not in accord with the almost invariably fatal clinical outcome of patients with GBM. The sensitivity of cells in vitro pertains to cells cultured in optimal nutritional conditions. The TCD 50 (the radiation dose necessary to control 50% of the tumors locally) determined in lab animals is analogous to the use of radiation with curative intent in clinical radiation oncology. The aim of the present study was (a) to evaluate the sensitivity of GBM in vivo relative to that of other tumor types and (b) assess the relationship between the single dose TCD 50 of the xenografts and the sensitivity of the corresponding cell lines in vitro. Methods and Materials: The TCD 50 assay was used to study twelve human tumor lines. Four previously published values were added. A total of 10 GBM, 4 squamous cell carcinoma (SCC), 1 soft tissue sarcoma (STS), and 1 cancer colon (CC) are included in the analysis. For further suppression of the residual immune system, all the animals received 6 Gy whole-body irradiation 1 day before transplantation. Local tumor irradiations were given as a single dose, under conditions of clamp hypoxia using a Cs irradiator. Results: The TCD 50 values for the 10 GBM xenografts varied between 32.5 and 75.2 Gy, with an average of 47.2 ± 13.1 Gy. The TCD 50 values for the SCC were similar to those of the GBM and ranged from 40.7 and 54.4 Gy, with a mean of 46.8 ± 6.4. The difference between the average TCD 50 of GBM and SCC was not significant. The STS and CC xenografts had TCD 50 values of 46.0 and 49.2 Gy, respectively. No correlation was found between the TCD 50 in vivo and the SF 2 or D 0 in vitro. Conclusions: Our data on GBM xenografts showed a wide range of sensitivities to single dose

In vivo radiation sensitivity of glioblastoma multiforme

Energy Technology Data Exchange (ETDEWEB)

Taghian, Alphonse; Freeman, Jill; Suit, Herman; DuBois, Willem; Budach, Wilfried; Baumann, Michael

1995-04-30

Purpose: Human glioblastoma (GBM) is one of the most resistant tumors to radiation. In previous reports, we have demonstrated a wide range of radiation sensitivity of GBM in vitro; that is, SF{sub 2} values of 0.2 to 0.8. The great sensitivity of some of the cell lines is not in accord with the almost invariably fatal clinical outcome of patients with GBM. The sensitivity of cells in vitro pertains to cells cultured in optimal nutritional conditions. The TCD{sub 50} (the radiation dose necessary to control 50% of the tumors locally) determined in lab animals is analogous to the use of radiation with curative intent in clinical radiation oncology. The aim of the present study was (a) to evaluate the sensitivity of GBM in vivo relative to that of other tumor types and (b) assess the relationship between the single dose TCD{sub 50} of the xenografts and the sensitivity of the corresponding cell lines in vitro. Methods and Materials: The TCD{sub 50} assay was used to study twelve human tumor lines. Four previously published values were added. A total of 10 GBM, 4 squamous cell carcinoma (SCC), 1 soft tissue sarcoma (STS), and 1 cancer colon (CC) are included in the analysis. For further suppression of the residual immune system, all the animals received 6 Gy whole-body irradiation 1 day before transplantation. Local tumor irradiations were given as a single dose, under conditions of clamp hypoxia using a Cs irradiator. Results: The TCD{sub 50} values for the 10 GBM xenografts varied between 32.5 and 75.2 Gy, with an average of 47.2 {+-} 13.1 Gy. The TCD{sub 50} values for the SCC were similar to those of the GBM and ranged from 40.7 and 54.4 Gy, with a mean of 46.8 {+-} 6.4. The difference between the average TCD{sub 50} of GBM and SCC was not significant. The STS and CC xenografts had TCD{sub 50} values of 46.0 and 49.2 Gy, respectively. No correlation was found between the TCD{sub 50} in vivo and the SF{sub 2} or D{sub 0} in vitro. Conclusions: Our data on GBM

Radiation sensitivity of human malignant lymphocytes

International Nuclear Information System (INIS)

Seshadri, R.; Matthews, C.; Morley, A.A.

1985-01-01

A simple and rapid in vitro technique to assess the sensitivity of human malignant lymphocytes to roentgen irradiation is described. A variety of established malignant lymphocyte cell lines were cloned in microwells and clone survival was used as the end-point. The survival of the clonogenic malignant lymphocyte down to a fraction of approximately 0.001 could be measured accurately. Except for a T-cell line, the radiation sensitivities of the cell lines were similar to that of normal T-lymphocytes. (orig.)

Sensitivity to ionizing radiation and chemotherapeutic agents in gemcitabine-resistant human tumor cell lines

International Nuclear Information System (INIS)

Bree, Chris van; Kreder, Natasja Castro; Loves, Willem J.P.; Franken, Nicolaas A.P.; Peters, Godefridus J.; Haveman, Jaap

2002-01-01

Purpose: To determine cross-resistance to anti-tumor treatments in 2',2'difluorodeoxycytidine (dFdC, gemcitabine)-resistant human tumor cells. Methods and Materials: Human lung carcinoma cells SW-1573 (SWp) were made resistant to dFdC (SWg). Sensitivity to cisplatin (cDDP), paclitaxel, 5-fluorouracil (5-FU), methotrexate (MTX), cytarabine (ara-C), and dFdC was measured by a proliferation assay. Radiosensitivity and radioenhancement by dFdC of this cell panel and the human ovarian carcinoma cell line A2780 and its dFdC-resistant variant AG6000 were determined by clonogenic assay. Bivariate flowcytometry was performed to study cell cycle changes. Results: In the SWg, a complete deoxycytidine kinase (dCK) deficiency was found on mRNA and protein level. This was accompanied by a 10-fold decrease in dCK activity which resulted in the >1000-fold resistance to dFdC. Sensitivity to other anti-tumor drugs was not altered, except for ara-C (>100-fold resistance). Radiosensitivity was not altered in the dFdC-resistant cell lines SWg and AG6000. High concentrations (50-100 μM dFdC) induced radioenhancement in the dFdC-resistant cell lines similar to the radioenhancement obtained at lower concentrations (10 nM dFdC) in the parental lines. An early S-phase arrest was found in all cell lines after dFdC treatment where radioenhancement was achieved. Conclusions: In the dFdC-resistant lung tumor cell line SWg, the deficiency in dCK is related to the resistance to dFdC and ara-C. No cross-resistance was observed to other anti-tumor drugs used for the treatment in lung cancer. Sensitivity to ionizing radiation was not altered in two different dFdC-resistant cell lines. Resistance to dFdC does not eliminate the ability of dFdC to sensitize cells to radiation

Irradiation of cells by single and double pulses of high intensity radiation: oxygen sensitization and diffusion kinetics

International Nuclear Information System (INIS)

Epp, E.R.; Ling, C.C.; Weiss, H.

1976-01-01

This paper discusses advances made on both experimental and theoretical approaches involving single and double pulses of high intensity ionizing radiation delivered to cultured bacterial and mammalian cells where the effect of oxygen is concerned. Information gained on the lifetime of oxygen-sensitive species suspected to be produced in critical molecules in irradiated cells and perhaps intimately related to the still unknown mechanisms of oxygen sensitization is described. The diffusion characteristics of oxygen at the cellular level obtained from experimental data are discussed. Current knowledge on intracellular radiolytic oxygen depletion is also presented. Future work on the use of high intensity pulsed radiation as a tool in cellular radiobiological research is outlined. It is expected that obtaining knowledge of the time available for damaged molecules to enter into chemical reactions may lead to insights into the mechanisms of radiation injury in cells, such as those involved in the oxygen effect. (Auth.)

Radiation sensitivity of T-lymphocytes from immunodeficient wasted mice

International Nuclear Information System (INIS)

Padilla, M.; Libertin, C.; Krco, C.; Woloschak, G.E.

1990-01-01

Mice with the autosomal recessive gene wasted (wst/wst) exhibit neurologic disorders, reduced mucosal immune responses, and abnormal DNA repair mechanisms. The wst/wst mouse has been proposed as a murine model for the human disorder ataxia telangiectasia. Experiments were designed to examine the sensitivity of T-cells from wasted mice to ionizing radiation. Results demonstrated that T-cell clones derived from wasted mice are more sensitive to the killing effects of gamma-rays than similar T-cell clones from control mice. Bulk thymocyte and splenic cell cultures demonstrated similar radiation sensitivity. Both thymic and splenic lymphocytes from wasted mice also expressed low proliferative responses to mitogenic stimulation with concanavalin A (Con A) that could not be attributed to an absence or reduction in T-cell number. However, following activation with Con A, cell cultures exhibited a marked decrease in the percentage of Thyl + cells in wasted mice, in contrast to cultures from control mice in which significant increases in Thyl + cells were observed. Furthermore, when cells were treated with gamma-rays in combination with Con A, Thyl + cells were decreased in control spleen and thymus, but were elevated in similarly treated wasted cultures. These changes were accompanied by an increase in cell volume in T-cells from wasted but not from control mice. These results describe the sensitivity of T-cells from wasted mice to ionizing radiation; in addition, they suggest that the wst/wst abnormality may be associated with cell cycle aberrancies

Intrinsic radiation resistance in human chondrosarcoma cells

International Nuclear Information System (INIS)

Moussavi-Harami, Farid; Mollano, Anthony; Martin, James A.; Ayoob, Andrew; Domann, Frederick E.; Gitelis, Steven; Buckwalter, Joseph A.

2006-01-01

Human chondrosarcomas rarely respond to radiation treatment, limiting the options for eradication of these tumors. The basis of radiation resistance in chondrosarcomas remains obscure. In normal cells radiation induces DNA damage that leads to growth arrest or death. However, cells that lack cell cycle control mechanisms needed for these responses show intrinsic radiation resistance. In previous work, we identified immortalized human chondrosarcoma cell lines that lacked p16 ink4a , one of the major tumor suppressor proteins that regulate the cell cycle. We hypothesized that the absence of p16 ink4a contributes to the intrinsic radiation resistance of chondrosarcomas and that restoring p16 ink4a expression would increase their radiation sensitivity. To test this we determined the effects of ectopic p16 ink4a expression on chondrosarcoma cell resistance to low-dose γ-irradiation (1-5 Gy). p16 ink4a expression significantly increased radiation sensitivity in clonogenic assays. Apoptosis did not increase significantly with radiation and was unaffected by p16 ink4a transduction of chondrosarcoma cells, indicating that mitotic catastrophe, rather than programmed cell death, was the predominant radiation effect. These results support the hypothesis that p16 ink4a plays a role in the radiation resistance of chondrosarcoma cell lines and suggests that restoring p16 expression will improve the radiation sensitivity of human chondrosarcomas

Silencing of poly(ADP-ribose) glycohydrolase sensitizes lung cancer cells to radiation through the abrogation of DNA damage checkpoint

Energy Technology Data Exchange (ETDEWEB)

Nakadate, Yusuke [Shien-Lab, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045 (Japan); Department of Bioengineering, Graduate School of Engineering, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan); Kodera, Yasuo; Kitamura, Yuka [Shien-Lab, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045 (Japan); Tachibana, Taro [Department of Bioengineering, Graduate School of Engineering, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan); Tamura, Tomohide [Division of Thoracic Oncology, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045 (Japan); Koizumi, Fumiaki, E-mail: fkoizumi@ncc.go.jp [Division of Thoracic Oncology, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045 (Japan)

2013-11-29

Highlights: •Radiosensitization by PARG silencing was observed in multiple lung cancer cells. •PAR accumulation was enhanced by PARG silencing after DNA damage. •Radiation-induced G2/M arrest and checkpoint activation were impaired by PARG siRNA. -- Abstract: Poly(ADP-ribose) glycohydrolase (PARG) is a major enzyme that plays a role in the degradation of poly(ADP-ribose) (PAR). PARG deficiency reportedly sensitizes cells to the effects of radiation. In lung cancer, however, it has not been fully elucidated. Here, we investigated whether PARG siRNA contributes to an increased radiosensitivity using 8 lung cancer cell lines. Among them, the silencing of PARG induced a radiosensitizing effect in 5 cell lines. Radiation-induced G2/M arrest was largely suppressed by PARG siRNA in PC-14 and A427 cells, which exhibited significantly enhanced radiosensitivity in response to PARG knockdown. On the other hand, a similar effect was not observed in H520 cells, which did not exhibit a radiosensitizing effect. Consistent with a cell cycle analysis, radiation-induced checkpoint signals were not well activated in the PC-14 and A427 cells when treated with PARG siRNA. These results suggest that the increased sensitivity to radiation induced by PARG knockdown occurs through the abrogation of radiation-induced G2/M arrest and checkpoint activation in lung cancer cells. Our findings indicate that PARG could be a potential target for lung cancer treatments when used in combination with radiotherapy.

Drug and radiation sensitivity measurements of successful primary monolayer culturing of human tumor cells using cell-adhesive matrix and supplemented medium

International Nuclear Information System (INIS)

Baker, F.L.; Spitzer, G.; Ajani, J.A.

1986-01-01

The limitations of the agar suspension culture method for primary culturing of human tumor cells prompted development of a monolayer system optimized for cell adhesion and growth. This method grew 83% of fresh human tumor cell biopsy specimens, cultured and not contaminated, from a heterogeneous group of 396 tumors including lung cancer (93 of 114, 82%); melanoma (54 of 72, 75%); sarcoma (46 of 59, 78%); breast cancer (35 of 39, 90%); ovarian cancer (16 of 21, 76%); and a miscellaneous group consisting of gastrointestinal, genitourinary, mesothelioma, and unknown primaries (78 of 91, 86%). Cell growth was characterized morphologically with Papanicolaoustained coverslip cultures and cytogenetically with Giemsastained metaphase spreads. Morphological features such as nuclear pleomorphism, chromatin condensation, basophilic cytoplasm, and melanin pigmentation were routinely seen. Aneuploid metaphases were seen in 90% of evaluable cultures, with 15 of 28 showing 70% or more aneuploid metaphases. Colony-forming efficiency ranged between 0.01 and 1% of viable tumor cells, with a median efficiency of 0.2%. This culture system uses a low inoculum of 25,000 viable cells per well which permitted chemosensitivity testing of nine drugs at four doses in duplicate from 2.2 X 10(6) viable tumor cells and radiation sensitivity testing at five doses in quadruplicate from 0.6 X 10(6) cells. Cultures were analyzed for survival by computerized image analysis of crystal violet-stained cells. Drug sensitivity studies showed variability in sensitivity and in survival curve shape with exponential cell killing for cisplatin, Adriamycin, and etoposide, and shouldered survival curves for 5-fluorouracil frequently seen. Radiation sensitivity studies also showed variability in both sensitivity and survival curve shape. Many cultures showed exponential cell killing, although others had shouldered survival curves

Superoxide dismutase amplifies organismal sensitivity to ionizing radiation

International Nuclear Information System (INIS)

Scott, M.D.; Meshnick, S.R.; Eaton, J.W.

1989-01-01

Although increased superoxide dismutase (SOD) activity is often associated with enhanced resistance of cells and organisms to oxidant challenges, few direct tests of the antioxidant importance of this enzyme have been carried out. To assess the importance of SOD in defending against gamma-radiation, we employed Escherichia coli with deficient, normal, and super-normal enzyme activities. Surprisingly, the radiation sensitivity of E. coli actually increases as bacterial SOD activity increases. Elevated intracellular SOD activity sensitizes E. coli to radiation-induced mortality, whereas SOD-deficient bacteria show normal or decreased radiosensitivity. Toxic effects of activated oxygen species are involved in this phenomenon; bacterial SOD activity has no effect on radiation sensitivity under anaerobic conditions or on the lethality of other, non-oxygen-dependent, toxins such as ultraviolet radiation

Radiation-sensitive genetically susceptible pediatric sub-populations

Energy Technology Data Exchange (ETDEWEB)

Kleinerman, Ruth A. [National Cancer Institute, NIH, DHHS, Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, Rockville, MD (United States)

2009-02-15

Major advances in pediatric cancer treatment have resulted in substantial improvements in survival. However, concern has emerged about the late effects of cancer therapy, especially radiation-related second cancers. Studies of childhood cancer patients with inherited cancer syndromes can provide insights into the interaction between radiation and genetic susceptibility to multiple cancers. Children with retinoblastoma (Rb), neurofibromatosis type 1 (NF1), Li-Fraumeni syndrome (LFS), and nevoid basal cell carcinoma syndrome (NBCCS) are at substantial risk of developing radiation-related second and third cancers. A radiation dose-response for bone and soft-tissue sarcomas has been observed in hereditary Rb patients, with many of these cancers occurring in the radiation field. Studies of NF1 patients irradiated for optic pathway gliomas have reported increased risks of developing another cancer associated with radiotherapy. High relative risks for second and third cancers were observed for a cohort of 200 LFS family members, especially children, possibly related to radiotherapy. Children with NBCCS are very sensitive to radiation and develop multiple basal cell cancers in irradiated areas. Clinicians following these patients should be aware of their increased genetic susceptibility to multiple primary malignancies enhanced by sensitivity to ionizing radiation. (orig.)

SiRNA-mediated IGF-1R inhibition sensitizes human colon cancer SW480 cells to radiation

International Nuclear Information System (INIS)

Yavari, Kamal; Taghikhani, Mohammad; Mesbah-Namin, Seyed A.; Maragheh, Mohammad Ghannadi; Babaei, Mohammad Hosein; Arfaee, Ali Jabbary; Madani, Hossein; Mirzaei, Hamid Reza

2010-01-01

Purpose. Insulin like growth factor receptor 1 (IGF-1R) is well-documented to play a key role in radiation response and tumor radiosensitivity, thus offering an attractive clinic drug target to enhance tumor sensitivity to anti-cancer radiotherapy. Material and methods. Human colon carcinoma SW480 cells were transfected with the specific small interference RNA (siRNA) expression vector (pkD-shRNA-IGF-1R-V2) designed to target IGF-1R mRNA. The expression of IGF-1R mRNA and its protein among the transfected and untransfected cells were detected by semi-quantitative RT-PCR and ELISA assay. The changes in cell radiosensitivity were examined by MTT assay. Results. Transfection of mammalian expression vector pkD containing IGF-1R siRNA was shown to reduce IGF-1R mRNA levels by up to 95%. ELISA assay detected a similar inhibition of IGF-1R protein levels in cells transfected with IGF-1R siRNA. SW480 cells transfected with the expression vector for siRNA significantly rendered cells more sensitive to radiation and the highest radiation enhancement ratio was 2.02 ± 0.08. Conclusion. These data provide the first evidence that specific siRNA fragment (pkD-shRNA-IGF-1R-V2) targeting human IGF-1R mRNA is able to enhance colon cancer radiosensitivity. Also results indicated that, combining IGF-1R siRNA and radiation significantly enhances antitumor efficacy compared with either modality alone

Cooperation between human cells sensitive to UVA radiations: a clue to the mechanism of cellular hypersensitivity associated with different clinical conditions

International Nuclear Information System (INIS)

Francis, A.J.; Giannelli, F.

1991-01-01

Six fibroblast strains sensitive to long wavelength ultraviolet radiation (UVA) and one control strain were used to see if cooperation between the different cell strains could modify the abnormally high yield of single-strand DNA breaks (SSB) in the sensitive strains caused by UVA irradiation in complete Dulbecco's MEM. The sensitive strains were established from individuals showing proneness to different types of light-induced skin damage (actinic reticuloid, familial actinic keratoses with internal malignancies, and unusual frequency of basal cell carcinomata). When sensitive and normal cells were cocultivated, the UVA-induced SSB decreased in the sensitive cells and increased in the normal ones by amounts proportional to the ratio of the two types of cells in the mixtures. Furthermore the regression of SSB, in the sensitive cells, on the proportion of normal cells in the mixture extrapolated to normal levels of SSB when the proportion of normal cells increased to one. Cocultivation of different sensitive cells did not reduce the UVA-induced SSB to levels below those of the less sensitive cell strains. From these results we conclude that substances, present in limiting amounts, even in normal cells, can be transferred from cell to cell, presumably by metabolic cooperation, and modify the yield of SSB caused by UVA radiation. The abnormal yields of SSB in the sensitive cells appear to be entirely attributable to deficits in the substances responsible for the intercellular cooperation. We suggest that such substances are small molecular weight scavengers of active oxygen species

Individual radiation sensitivity: implications in medical practice

Energy Technology Data Exchange (ETDEWEB)

Gisone, P.; Dubner, D.; Perez, M.D.R.; Michelin, S.; Di Giogio, M. [Autoridad Regulatoria Nuclear, Buenos Aires (Argentina); Bourguignon, M. [Direction Generale de la Surete Nucleaire et de la Radioprotection, Paris (France)

2006-07-01

Important advances in radiotherapy and nuclear medicine towards better treatment modalities and safer applications have taken place in recent years. Progress in medical imaging, better tumour targeting and optimization of radiation delivery have allowed for dose escalation and improved patient outcome. However, the tolerance of normal tissues constitutes the limiting factor for dose escalation in therapeutical uses of ionizing radiation (IR). Patients vary considerably in their normal tissue response to IR even after similar treatments. As many as 5% of cancer patients develop severe effects to external radiation therapy in normal tissues within the treatment field: they may include acute effects such as erythema and desquamation of the exposed skin and mucosa that appear during or directly after radiotherapy, late effects developed months or years later, such as fibrosis and telangiectasia and cancer induction. Several patient and treatment related factors are known to influence the variability of side effects, however up to a 70% of the total variance of normal tissue radiation response remained unexplained. Thus, individual sensitivity to IR, i.e. hypersensitivity to carcinogenic risks (stochastic effects) and hypersensitivity to deterministic effects, is becoming an important issue in oncology and raises questions regarding the underlying mechanisms. The mechanisms of DNA repair, the signalling pathways involved in radiation sensitivity and non-targeted effects are key aspects, essential to understanding radiation effects at genetic level. Moreover, human genetic diseases that combine higher incidence of cancer and hypersensitivity to IR are associated with defects in cell response to DNA damage. Therefore, much interest has raised during the last years in the developing of predictive tests capable to detect in advance such hypersensitive conditions. The goal of this presentation is to review the possible mechanisms involved in genetic and epigenetic

Individual radiation sensitivity: implications in medical practice

International Nuclear Information System (INIS)

Gisone, P.; Dubner, D.; Perez, M.D.R.; Michelin, S.; Di Giogio, M.; Bourguignon, M.

2006-01-01

Important advances in radiotherapy and nuclear medicine towards better treatment modalities and safer applications have taken place in recent years. Progress in medical imaging, better tumour targeting and optimization of radiation delivery have allowed for dose escalation and improved patient outcome. However, the tolerance of normal tissues constitutes the limiting factor for dose escalation in therapeutical uses of ionizing radiation (IR). Patients vary considerably in their normal tissue response to IR even after similar treatments. As many as 5% of cancer patients develop severe effects to external radiation therapy in normal tissues within the treatment field: they may include acute effects such as erythema and desquamation of the exposed skin and mucosa that appear during or directly after radiotherapy, late effects developed months or years later, such as fibrosis and telangiectasia and cancer induction. Several patient and treatment related factors are known to influence the variability of side effects, however up to a 70% of the total variance of normal tissue radiation response remained unexplained. Thus, individual sensitivity to IR, i.e. hypersensitivity to carcinogenic risks (stochastic effects) and hypersensitivity to deterministic effects, is becoming an important issue in oncology and raises questions regarding the underlying mechanisms. The mechanisms of DNA repair, the signalling pathways involved in radiation sensitivity and non-targeted effects are key aspects, essential to understanding radiation effects at genetic level. Moreover, human genetic diseases that combine higher incidence of cancer and hypersensitivity to IR are associated with defects in cell response to DNA damage. Therefore, much interest has raised during the last years in the developing of predictive tests capable to detect in advance such hypersensitive conditions. The goal of this presentation is to review the possible mechanisms involved in genetic and epigenetic

Novel concepts in modification of radiation sensitivity

International Nuclear Information System (INIS)

Bump, E.A.; Palayoor, S.T.; Lai, L.L.; Cerce, B.A.; Langley, R.E.; Coleman, C.N.; Braunhut, S.J.

1994-01-01

The purpose of this study was to determine whether biological effects of radiation, such as apoptosis, that differ from classical clonogenic cell killing, can be modified with agents that would not be expected to modify classical clonogenic cell killing. This would expand the range of potential modifiers of radiation therapy. EL4 murine lymphoma cell apoptosis was determined by electrophoretic analysis of deoxyribonucleic acid (DNA) fragmentation. DNA was extracted 24 h after irradiation or addition of inducing agents. Modifiers of radiation-induced apoptosis were added immediately after irradiation. The effects of radiation on wounded endothelial monolayers were studied by scraping a line across the monolayer 30 min after irradiation. Cell detachment was used as an endpoint to determine the protective effect of prolonged exposure to retinol prior to irradiation. EL4 cell apoptosis can be induced by tert-butyl hydroperoxide or the glutathione oxidant SR-4077. Radiation-induced EL4 cell apoptosis can be inhibited with 3-aminobenzamide, an agent that sensitizes cells to classical clonogenic cell killing. Radiation-induced endothelial cell detachment from confluent monolayers can be modified by pretreatment with retinol. These results raise the possibility that radiation could induce apoptosis by an oxidative stress mechanism that is different from that involved in classical clonogenic cell killing. These and other recent findings encourage the notion that differential modification of classical clonogenic cell killing and other important endpoints of radiation action may be possible. 47 refs., 3 figs

Apoptotic potential and cell sensitivity to fractionated radiotherapy

International Nuclear Information System (INIS)

Rupnow, Brent A.; Murtha, Albert D.; Alarcon, Rodolfo M.; Giaccia, Amato J.; Knox, Susan J.

1997-01-01

Purpose/Objective: At present, the relationship between sensitivity to radiation-induced apoptosis and overall cellular radiosensitivity remains unclear. In particular, the relationship of apoptotic sensitivity to the survival of cells following fractionated irradiation has not been well studied. The purpose of the present study was to determine if increasing cell sensitivity to radiation-induced apoptosis would result in decreased clonogenic survival following single dose and fractionated irradiation in vitro. Materials and Methods: To address this, we chose a cell line (Rat-1MycER) in which the sensitivity to radiation-induced apoptosis could be altered by switching on or off the activity of a conditional c-Myc allele (c-MycER). The c-MycER construct expresses a full length c-Myc protein fused to a modified hormone binding domain of the estrogen receptor. Only in the presence of the estrogen analog 4-hydroxytamoxifen (4HT), does the conditional c-MycER become active. Apoptosis following irradiation in these cells (with and without c-MycER activation) was analyzed by flow cytometry to determine the percentage of cells undergoing apoptosis following various radiation doses and at different times after irradiation. Additionally, clonogenic survival analysis was performed following single radiation doses from 0 to 10 Gy and following five fractions of 2 or 4 Gy each. Survival of cells with and without c-MycER activation was compared. Furthermore, the effect of overexpressing the anti-apoptotic Bcl-2 gene on apoptosis induction and clonogenic survival of these cells was examined. Results: Rat-1MycER cells were strongly sensitized to radiation-induced apoptosis in a dose and time dependent manner when MycER was activated relative to cells treated without c-MycER activation. This c-Myc-mediated sensitivity to radiation-induced apoptosis was suppressed by overexpression of the anti-apoptotic protein Bcl-2. In addition to increasing apoptosis, activating c-MycER prior to

Physical determinants of radiation sensitivity in bacterial spores

International Nuclear Information System (INIS)

Powers, E.L.

1982-01-01

Several factors modifying radiation sensitivity in dry bacterial spores are described and discussed. Vacuum inducing the loss of critical structural water, very low dose rates of radiation from which the cell may recover, radiations of high linear energy transfer, and the action of temperature over long periods of time on previously irradiated cells are recognized from extensive laboratory work as important in determining survival of spores exposed to low radiation doses at low temperatures for long periods of time. Some extensions of laboratory work are proposed

Experimental investigations on the relationship between radiation dose and sensitization of hypoxic cells by electron affinic compounds. Coordinated programme on improvement in radiotherapy of cancer using modifiers of radiosensitivity of cells

International Nuclear Information System (INIS)

Revesz, L.

1981-12-01

The investigations concern experimental studies on the factors which determine the inherent radiation response of mammalian cells, and the mechanism by which treatment with radiation protectors and hypoxic sensitizers modifies the response. Several mammalian cell lines including some derived from humans, were used in the tests of the biological response to radiation. Especially, the establishment of glutathione-deficient cell lines opened new experimental approaches to the question on the role of aminothiols in determining cellular radiation response. As the endpoints for the effect of radiation, single-strand DNA breaks by means of the sucrose gradient centrifugation and the unwinding technique in weak alkali, and colony forming ability of the cells were chosen. Radical reactions were also studied by the pulse-radiolysis technique. The enhancement of cellular radiosensitivity by oxygen and hypoxic cell sensitizers was found to be directly related to the glutathione level in the cells. Some particular aminothiols could substitute for the effect of glutathione in protecting against sensitization by oxygen and oxygen mimic sensitizers. The post irradiation repair of some DNA lesions induced by oxygen or hypoxic cell sensitizers was also associated with the level of glutathione and some specific aminothiols in the cells. The experiments revealed an efficient cellular cooperation in the repair of radiation induced DNA damage. Pulse radiolysis studies showed radical reactions characteristic for glutathione and not shared by other naturally occurring aminothiols. Inherent glutathione appears to play an important role in determining the intrinsic radiosensitivity of cells and the result of treatment with radioprotective and radiosensitizing substances. In particular, glutathione participates in both immediate radical reactions following exposure to ionizing radiation, and in the subsequent biochemical processes, and functions in promoting repair of the radiation damage

Characterization of new radiation-sensitive mutant, Escherichia coli K-12 radC102

International Nuclear Information System (INIS)

Felzenszwalb, I.; Sargentini, N.J.; Smith, K.C.

1984-01-01

A new radiation-sensitive mutant, radC, has been isolated. The radC gene is located at 81.0 min on the Escherichia coli K-12 linkage map. The radC mutation sensitized cells to uv radiation, but unlike most DNA repair mutations, sensitization to X rays was observed only for rich medium-grown cells. For cells grown in rich medium, the radC mutant was normal for γ radiation mutagenesis, but showed less uv-radiation mutagenesis than the wild-type strain; it showed normal amount of X- and uv-radiation-induced DNA degradation, and it wasapprox. =60% deficient in recombination ability. The radC strain was normal for host cell reactivation of γ and uv-irradiated bacteriophage the radC mutation did not sensitize a recA strain, but did sensitize a radA and a polA strain to X and uv radiation and a uvrA strain to uv radiation. Therefore, it is suggested that the radC gene product plays a role in the growth medium-dependent, recA gene-dependent repair of DNA single-strand breaks after X irradiation, and in postreplication repair after uv irradiation

Changes in sensitivity to radiation and to bleomycin occurring during the life history of monolayer cultures of a mouse tumour cell line

International Nuclear Information System (INIS)

Twentyman, P.R.; Bleehen, N.M.

1975-01-01

The response to X-radiation and to bleomycin has been measured at a number of times during the life of monolayer cultures of EMT6 mouse tumour cells. Little change in radiation sensitivity was seen at any time and no loss of the shoulder to the survival curve occurred. Cultures in early plateau phase (where a considerable amount of cell proliferation is balanced by cell loss) showed a reduced sensitivity to bleomycin when compared with cells in exponential growth. However, after a longer period in plateau phase, when proliferation had virtually ceased, the sensitivity became greater than that of exponential phase cells. These findings are discussed with reference to the conflicting results of other workers. (author)

Role of mitochondria in radiation sensitivity

International Nuclear Information System (INIS)

Indo, Hiroko; Tomita, Kazuo; Majima, Hideyuki; Matsui, Hirofumi; Ozawa, Toshihiko

2007-01-01

This paper describes mainly the role of mitochondrial (Mt) manganese superoxide dismutase (MnSOD) for deciding the radiation sensitivity of cells. The fact that Mt concerns with apoptosis has been shown by the finding that change in Mt membrane potential relates with the cell death. Mt has the electron transport system to yield the cellular energy molecule (ATP) and from which electrons are leaked out in 2-3%, a considerably large proportion in a cell. The electrons react with oxygen nearby to yield SO (O 2 ·- ), which in turn induces apoptosis through oxidation stress (OS). On the other hand, MnSOD is transported in Mt from cytoplasm and excludes the reactive oxygen species (ROS) like SO. Studies by MnSOD gene-deletion, knockout, cDNA-transfection, and transgenesis have indicated MnSOD is essential for keeping life and resistance to OS. Authors have shown that overexpression of Mt MnSOD protects against radiation-induced cell death, suggesting that Mt participates in radiation sensitivity where SO is involved. Interestingly, MnSOD activity is low in cancer cells, its overexpression results in tumor suppression and MnSOD is a target in leukemia therapy. When MTS (Mt targeting sequence, necessary for the enzyme to enter Mt)-deleted MnSOD is transfected, cells lack resistance to radiation, indicating the enzyme must be present in Mt. Mt DNA damage leading to electron transport system impairment is found to increase ROS, and to be reversed by the transfection of MnSOD gene. Studies of Mt DNA damage in cancer cells where aerobic glycolysis is actively operated, are currently in progress lively, and are thought to promote the development of diagnosis and treatment of cancer. (R.T.)

Toward the elucidation of factors concerning the individual difference of radiation sensitivity, and the reduction of radiation risks

International Nuclear Information System (INIS)

Nenoi, Mitsuru; Nakajima, Tetsuo; Wang, Bing

2013-01-01

This article describes studies aiming at the title subject and contains 2 topics of genetic and non-genetic factors modifying the radiation sensitivity. The ultimate purposes of those studies are the introduction of individual weighting factor to correct the individual differences of the sensitivity (IDS) and the practical control of the sensitivity-concerned factors, in the field of medical exposure. For genetic factors, described are studies on factors modifying the sensitivity at DNA repair and on the control of the sensitivity through the DNA repairing factors. The former, using cultured cells, aims at identifying protein (gene) of possible biomarker for IDS in non-homologous end-joining (NHEJ), an important mechanism in repairing the double strand break of DNA. Ku protein is found as the candidate. The latter has revealed that cells lacking Artemis, XRCC4 or MDC1 gene are highly sensitive, and are planning to suppress Artemis activity artificially, which may lead to the reduction of radiation cancer formation due to the death of highly sensitive cells. For non-genetic factors, described are studies on the life habits modifying the sensitivity, on the control of the sensitivity through the radiation-induced adaptive response and with steroid hormone. In the first, in mice treated with high-calorie diet and X-irradiation, a possible radiation response is suggested in the hepatic DNA-methylation and micro-RNA. Second, the combination of radiation adaptive response in the genome damage and restriction of diet ingestion is shown to lower the sensitivity of mice with use of C, Ne ion or X-ray irradiation. Third, in studies on the radiation-induced formation and condensation of breast cancer stem cells in the presence of progesterone, the hormone is found to produce micro-RNA molecules relating with the suppression of cellular senescence and repressed carcinogenesis with over-expression of apoptosis inhibitory molecules. (T.T.)

Effect of a hypoxic cell sensitizer doranidazole on the radiation-induced apoptosis of mouse L5178Y lymphoma cells

International Nuclear Information System (INIS)

Aoki, Mizuho; Furusawa, Yoshiya; Shibamoto, Yuta

2002-01-01

We investigated the sensitizing effect of the 2-nitroimidazole analogue doranidazole, a new hypoxic radiosensitizer, on radiation-induced apoptosis in L5178Y cells. Apoptosis was assessed by checking DNA ladder formation, the presence of sub-G1 peaks in flow cytometry, and chromation condensation. A radiosensitizing effect of doranidazole was also confirmed by a soft-agar colony assay of surviving cells. In the assay of DNA ladder formation, DNA fragmentation was observed following irradiation under an aerobic or hypoxic condition with or without doranidazole. The proportions of the cells at the sub-G1 peak in a flow cytometric measurement was not very different among the irradiations at 5 Gy under the aerobic condition, 15 Gy under hypoxia, and 10 Gy with 1 mM doranidazole under hypoxia. The fraction of cells with chromatin condensation was found to be significantly increased with doranidazole up to 3 mM when applied under hypoxic irradiation, but did not increase even at 10 mM. The sensitizer enhancement ratio was estimated to be about 1.7 with a concentration of 1 mM. This enhancement ratio was not different from that observed by assaying cell survivals. On the other hand, doranidazole showed no radiosensitizing effect under aerobic conditions with 1 mM. In conclusion, the radiation-induced apoptosis of L5178Y cells was enhanced by doranidazole under hypoxia. (author)

Changes in bacterial radiation sensitivity due to deuterium substitution

International Nuclear Information System (INIS)

Strauss, A.; Weiss, H.

1985-01-01

The influence of deuterium substitution for hydrogen on radiation sensitivity was measured under various conditions for E. coli B/r irradiated by 450 kev electrons in single intense pulses. Cells were grown in a nutrient medium made from a deuterium oxide based solution. They were suspended in a D/sub 2/O based buffered saline and plated in thin aqueous layers on membrane filters and irradiated in 100% N/sub 2/ or 100% O/sub 2/. Comparisons were made to cells similarly plated and irradiated but grown instead in a water based nutrient medium and suspended in either a water based or a D/sub 2/O based buffered saline. For the conventionally grown cells, D/sub 2/O increased the radiation sensitivity in both gases by about 10%. For cells grown and suspended with D/sub 2/O based media, a 50% reduction of radiation sensitivity was found with both gas and an increased extrapolation number was observed. In this latter method, deuterium is more fully substituted for hydrogen in the molecular substrate of the cell. These cells were also irradiated over a temperature range of 2 0 C to 43 0 C after being suspended in deuterated ethanol. Speculations for the changes induced by the substitution are presented

Familial melanoma associated with dominant ultraviolet radiation sensitivity

International Nuclear Information System (INIS)

Ramsay, R.G.; Chen, P.; Imray, F.P.; Kidson, C.; Lavin, M.F.; Hockey, A.

1982-01-01

Sensitivity to ultraviolet radiation was studied in lymphoblastoid cell lines derived from 32 members of two families with histories of multiple primary melanomas in several generations. As assayed by colony formation in agar or by trypan blue exclusion following irradiation, cellular sensitivity showed a bimodal distribution. All persons with melanoma or multiple moles were in the sensitive group, while some family members exhibited responses similar to those of controls. Cells from four cases of sporadic melanoma showed normal levels of sensitivity. The data are consistent with a dominantly inherited ultraviolet light sensitivity associated with these examples of familial melanoma. Spontaneous and ultraviolet light-induced sister chromatid exchange frequencies were similar to those in control cell lines. No defect in excision repair was detected in any of the above cell lines, but the sensitive group showed postirradiation inhibition of DNA replication intermediate between controls and an excision-deficient xeroderma pigmentosum cell line

Effects of sensitizers on cell respiration. 3. The effects of hypoxic cell radiosensitizers on oxidative metabolism and the radiation response of an in vitro tumour model

Energy Technology Data Exchange (ETDEWEB)

Durand, R E [Wisconsin Clinical Cancer Center, Madison (USA). Dept. of Human Oncology; Biaglow, J E; Greenstock, C L

1978-06-01

Physiological factors are important when considering the effects of radiosensitizers on the radiation response of complex systems such as multi-cellular spheroids. In this system, under conditions of unlimited nutrient supply, cells are rendered hypoxic by metabolism. Thus, using the spheroid system as an in vitro model of the tumour-cell microenvironment, we have determined the relative contribution of radiosensitization and respiratory effects of a number of electron-affinic sensitizers having potential clinical use. These studies are indicative of physiological responses at the cellular level, and suggest optimal drug administration schemes for obtaining maximal radiation response in vivo with hypoxic cell sensitizers.

Susceptibility of ATM-deficient pancreatic cancer cells to radiation.

Science.gov (United States)

Ayars, Michael; Eshleman, James; Goggins, Michael

2017-05-19

Ataxia telangiectasia mutated (ATM) is inactivated in a significant minority of pancreatic ductal adenocarcinomas and may be predictor of treatment response. We determined if ATM deficiency renders pancreatic cancer cells more sensitive to fractionated radiation or commonly used chemotherapeutics. ATM expression was knocked down in three pancreatic cancer cell lines using ATM-targeting shRNA. Isogenic cell lines were tested for sensitivity to several chemotherapeutic agents and radiation. DNA repair kinetics were analyzed in irradiated cells using the comet assay. We find that while rendering pancreatic cancer cells ATM-deficient did not significantly change their sensitivity to several chemotherapeutics, it did render them exquisitely sensitized to radiation. Pancreatic cancer ATM status may help predict response to radiotherapy.

Suppression of DNA-dependent protein kinase sensitize cells to radiation without affecting DSB repair

International Nuclear Information System (INIS)

Gustafsson, Ann-Sofie; Abramenkovs, Andris; Stenerlöw, Bo

2014-01-01

Highlights: • We reduced the level of DNA-PKcs with siRNA and examined cells after γ-irradiation. • Low DNA-PKcs levels lead to radiosensitivity but did not affect repair of DSB. • Low DNA-PKcs levels may block progression of mitosis. • DNA-PKcs role in mitotic progression is independent of its role in DSB repair. • We suggest different mechanisms by which loss of DNA-PKcs function sensitize cells. - Abstract: Efficient and correct repair of DNA double-strand break (DSB) is critical for cell survival. Defects in the DNA repair may lead to cell death, genomic instability and development of cancer. The catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) is an essential component of the non-homologous end joining (NHEJ) which is the major DSB repair pathway in mammalian cells. In the present study, by using siRNA against DNA-PKcs in four human cell lines, we examined how low levels of DNA-PKcs affected cellular response to ionizing radiation. Decrease of DNA-PKcs levels by 80–95%, induced by siRNA treatment, lead to extreme radiosensitivity, similar to that seen in cells completely lacking DNA-PKcs and low levels of DNA-PKcs promoted cell accumulation in G2/M phase after irradiation and blocked progression of mitosis. Surprisingly, low levels of DNA-PKcs did not affect the repair capacity and the removal of 53BP1 or γ-H2AX foci and rejoining of DSB appeared normal. This was in strong contrast to cells completely lacking DNA-PKcs and cells treated with the DNA-PKcs inhibitor NU7441, in which DSB repair were severely compromised. This suggests that there are different mechanisms by which loss of DNA-PKcs functions can sensitize cells to ionizing radiation. Further, foci of phosphorylated DNA-PKcs (T2609 and S2056) co-localized with DSB and this was independent of the amount of DNA-PKcs but foci of DNA-PKcs was only seen in siRNA-treated cells. Our study emphasizes on the critical role of DNA-PKcs for maintaining survival after radiation exposure

Suppression of DNA-dependent protein kinase sensitize cells to radiation without affecting DSB repair

Energy Technology Data Exchange (ETDEWEB)

Gustafsson, Ann-Sofie, E-mail: ann-sofie.gustafsson@bms.uu.se; Abramenkovs, Andris; Stenerlöw, Bo

2014-11-15

Highlights: • We reduced the level of DNA-PKcs with siRNA and examined cells after γ-irradiation. • Low DNA-PKcs levels lead to radiosensitivity but did not affect repair of DSB. • Low DNA-PKcs levels may block progression of mitosis. • DNA-PKcs role in mitotic progression is independent of its role in DSB repair. • We suggest different mechanisms by which loss of DNA-PKcs function sensitize cells. - Abstract: Efficient and correct repair of DNA double-strand break (DSB) is critical for cell survival. Defects in the DNA repair may lead to cell death, genomic instability and development of cancer. The catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) is an essential component of the non-homologous end joining (NHEJ) which is the major DSB repair pathway in mammalian cells. In the present study, by using siRNA against DNA-PKcs in four human cell lines, we examined how low levels of DNA-PKcs affected cellular response to ionizing radiation. Decrease of DNA-PKcs levels by 80–95%, induced by siRNA treatment, lead to extreme radiosensitivity, similar to that seen in cells completely lacking DNA-PKcs and low levels of DNA-PKcs promoted cell accumulation in G2/M phase after irradiation and blocked progression of mitosis. Surprisingly, low levels of DNA-PKcs did not affect the repair capacity and the removal of 53BP1 or γ-H2AX foci and rejoining of DSB appeared normal. This was in strong contrast to cells completely lacking DNA-PKcs and cells treated with the DNA-PKcs inhibitor NU7441, in which DSB repair were severely compromised. This suggests that there are different mechanisms by which loss of DNA-PKcs functions can sensitize cells to ionizing radiation. Further, foci of phosphorylated DNA-PKcs (T2609 and S2056) co-localized with DSB and this was independent of the amount of DNA-PKcs but foci of DNA-PKcs was only seen in siRNA-treated cells. Our study emphasizes on the critical role of DNA-PKcs for maintaining survival after radiation exposure

Effects of radiation sensitivity of 17-DMAG on hypoxic carcinima cells

International Nuclear Information System (INIS)

Wu Xiaofen; Hong Chengjiao; Zhang Baoguo

2011-01-01

Objective: To investigate the radiosensitivity effect of 17-DMAG on human HeLa cells of cervical cancer, which was induced by Hypoxia mimetic cobalt chloride(CoCl 2 ). Methods: First, HeLa cells was treated by different concentrations of CoCl 2 for 24 hours. And HIF-1α protein level was detected by Western blot analysis. Then the HeLa cells was dealed with CoCl 2 in concentration of 200 μmol/L. Cells were pre-treated with different concentrations of 17-DMAG 16h after receiving different doses of 2, 4, 6, 8 Gy irradiation. The method of colony-forming was used to detect the radiation sensitivity. HIF-la protein level was detected by Western blot analysis. Results: When CoCl 2 was in concentration in 200 μmol/L, the HIF-1a protein expression was highest; HeLa cells were cultured in different concenreations of 17-DMAG and exposed to different doses of Irradiation, the cell servival rate was significant(P<0.01); After 17-DMAG pretreatment hypoxia of HeLa cells, HIF-1a protein expression with the drug concentration were inhibited significantly. Conclusions: 17-DMAG pretreatment hypoxia of HeLa cells can enhance radiosensitization and the mechanism may be through inhibition of HIF-1a protein expression. (authors)

Unique proteomic signature for radiation sensitive patients; a comparative study between normo-sensitive and radiation sensitive breast cancer patients

Energy Technology Data Exchange (ETDEWEB)

Skiöld, Sara [Center for Radiation Protection Research, Department of Molecular Biosciences, The Wernner-Gren Institute, Stockholm University, Stockholm (Sweden); Azimzadeh, Omid [Institute of Radiation Biology, German Research Center for Environmental Health, Helmholtz Zentrum München (Germany); Merl-Pham, Juliane [Research Unit Protein Science, German Research Center for Environmental Health, Helmholtz Zentrum München, Neuherberg (Germany); Naslund, Ingemar; Wersall, Peter; Lidbrink, Elisabet [Division of Radiotherapy, Radiumhemmet, Karolinska University Hospital, Stockholm (Sweden); Tapio, Soile [Institute of Radiation Biology, German Research Center for Environmental Health, Helmholtz Zentrum München (Germany); Harms-Ringdahl, Mats [Center for Radiation Protection Research, Department of Molecular Biosciences, The Wernner-Gren Institute, Stockholm University, Stockholm (Sweden); Haghdoost, Siamak, E-mail: Siamak.Haghdoost@su.se [Center for Radiation Protection Research, Department of Molecular Biosciences, The Wernner-Gren Institute, Stockholm University, Stockholm (Sweden)

2015-06-15

Highlights: • The unique protein expression profiles were found that separate radiosensitive from normal sensitive breast cancer patients. • The oxidative stress response, coagulation properties and acute phase response suggested to be the hallmarks of radiation sensitivity. - Abstract: Radiation therapy is a cornerstone of modern cancer treatment. Understanding the mechanisms behind normal tissue sensitivity is essential in order to minimize adverse side effects and yet to prevent local cancer reoccurrence. The aim of this study was to identify biomarkers of radiation sensitivity to enable personalized cancer treatment. To investigate the mechanisms behind radiation sensitivity a pilot study was made where eight radiation-sensitive and nine normo-sensitive patients were selected from a cohort of 2914 breast cancer patients, based on acute tissue reactions after radiation therapy. Whole blood was sampled and irradiated in vitro with 0, 1, or 150 mGy followed by 3 h incubation at 37 °C. The leukocytes of the two groups were isolated, pooled and protein expression profiles were investigated using isotope-coded protein labeling method (ICPL). First, leukocytes from the in vitro irradiated whole blood from normo-sensitive and extremely sensitive patients were compared to the non-irradiated controls. To validate this first study a second ICPL analysis comparing only the non-irradiated samples was conducted. Both approaches showed unique proteomic signatures separating the two groups at the basal level and after doses of 1 and 150 mGy. Pathway analyses of both proteomic approaches suggest that oxidative stress response, coagulation properties and acute phase response are hallmarks of radiation sensitivity supporting our previous study on oxidative stress response. This investigation provides unique characteristics of radiation sensitivity essential for individualized radiation therapy.

Unique proteomic signature for radiation sensitive patients; a comparative study between normo-sensitive and radiation sensitive breast cancer patients

International Nuclear Information System (INIS)

Skiöld, Sara; Azimzadeh, Omid; Merl-Pham, Juliane; Naslund, Ingemar; Wersall, Peter; Lidbrink, Elisabet; Tapio, Soile; Harms-Ringdahl, Mats; Haghdoost, Siamak

2015-01-01

Highlights: • The unique protein expression profiles were found that separate radiosensitive from normal sensitive breast cancer patients. • The oxidative stress response, coagulation properties and acute phase response suggested to be the hallmarks of radiation sensitivity. - Abstract: Radiation therapy is a cornerstone of modern cancer treatment. Understanding the mechanisms behind normal tissue sensitivity is essential in order to minimize adverse side effects and yet to prevent local cancer reoccurrence. The aim of this study was to identify biomarkers of radiation sensitivity to enable personalized cancer treatment. To investigate the mechanisms behind radiation sensitivity a pilot study was made where eight radiation-sensitive and nine normo-sensitive patients were selected from a cohort of 2914 breast cancer patients, based on acute tissue reactions after radiation therapy. Whole blood was sampled and irradiated in vitro with 0, 1, or 150 mGy followed by 3 h incubation at 37 °C. The leukocytes of the two groups were isolated, pooled and protein expression profiles were investigated using isotope-coded protein labeling method (ICPL). First, leukocytes from the in vitro irradiated whole blood from normo-sensitive and extremely sensitive patients were compared to the non-irradiated controls. To validate this first study a second ICPL analysis comparing only the non-irradiated samples was conducted. Both approaches showed unique proteomic signatures separating the two groups at the basal level and after doses of 1 and 150 mGy. Pathway analyses of both proteomic approaches suggest that oxidative stress response, coagulation properties and acute phase response are hallmarks of radiation sensitivity supporting our previous study on oxidative stress response. This investigation provides unique characteristics of radiation sensitivity essential for individualized radiation therapy

Inhibition of ERK1/2 or AKT Activity Equally Enhances Radiation Sensitization in B16F10 Cells

Science.gov (United States)

Kalal, Bhuvanesh Sukhlal; Fathima, Faraz; Pai, Vinitha Ramanath; Sanjeev, Ganesh; Krishna, Chilakapati Murali; Upadhya, Dinesh

2018-01-01

Background The aim of the study was to evaluate the radiation sensitizing ability of ERK1/2, PI3K-AKT and JNK inhibitors in highly radiation resistant and metastatic B16F10 cells which carry wild-type Ras and Braf. Methods Mouse melanoma cell line B16F10 was exposed to 1.0, 2.0 and 3.0 Gy of electron beam radiation. Phosphorylated ERK1/2, AKT and JNK levels were estimated by ELISA. Cells were exposed to 2.0 and 3.0 Gy of radiation with or without prior pharmacological inhibition of ERK1/2, AKT as well as JNK pathways. Cell death induced by radiation as well as upon inhibition of these pathways was measured by TUNEL assay using flow cytometry. Results Exposure of B16F10 cells to 1.0, 2.0 and 3.0 Gy of electron beam irradiation triggered an increase in all the three phosphorylated proteins compared to sham-treated and control groups. B16F10 cells pre-treated with either ERK1/2 or AKT inhibitors equally enhanced radiation-induced cell death at 2.0 as well as 3.0 Gy (P < 0.001), while inhibition of JNK pathway increased radiation-induced cell death to a lesser extent. Interestingly combined inhibition of ERK1/2 or AKT pathways did not show additional cell death compared to individual ERK1/2 or AKT inhibition. This indicates that ERK1/2 or AKT mediates radiation resistance through common downstream molecules in B16F10 cells. Conclusions Even without activating mutations in Ras or Braf genes, ERK1/2 and AKT play a critical role in B16F10 cell survival upon radiation exposure and possibly act through common downstream effector/s. PMID:29581812

Radiation sensitivity of tumour cells stained in vitro or in vivo with the bisbenzimide fluorochrome Hoechst 33342

Energy Technology Data Exchange (ETDEWEB)

Young, S D; Hill, R P [Ontario Cancer Inst., Toronto, ON (Canada)

1989-11-01

The DNA-binding bisbenzimide fluorochrome Hoechst 33342 is being used routinely in radio-biological studies to assess cell kinetic parameters and tumour blood flow. Results indicate that the amount of H33342 accumulated by cells may affect the radiation sensitivity of populations exposed to high concentrations of this fluorochrome, such as those required to achieve stoichiometric binding to DNA. (author).

Radiation effects on cultured human lymphoid cells

International Nuclear Information System (INIS)

Johansson, L.; Nilsson, K.; Carlsson, J.; Larsson, B.; Jakobsson, P.

1981-01-01

The cloning efficiency of human normal and malignant lymphoid cells is usually low. Radiation effects in vitro on such cells can therefore not be analysed with conventional cloning. However, this problem can be circumscribed by using the growth extrapolation method. A panel of human leukemia-lymphoma cell-lines representing Epstein-Barr virus carrying lymphoblastoid cells of presumed non-neoplastic derivation and neoplastic T- and B-lymphocytes was used to test the efficiency of this method. The sensitivity to radiation could be determined for all these cell types. The growth extrapolation method gave generally the same result as conventional cloning demonstrated by comparison with one exceptional cell-line with capacity for cloning in agar. The sensitivity varied largely between the different cell types. A common feature was that none of the cell lines had a good capacity to accumulate sublethal radiation injury. (Auth.)

How far is cancer cured by radiation sensitization?

International Nuclear Information System (INIS)

Ando, Koichi; Sasaki, Takehito; Ikeda, Hiroshi

1990-01-01

Some types of cancer are not cured by radiation alone in view of histology, location, and size. In facing so-called radioresistant cancer, antineoplastic agents, hypoxic cell sensitizers, biological response modifiers, or hyperthermia are used in combination with radiation, with the aim of cancer cure. First of all, this chapter discusses the subject of 'what is tumor cure by radiation therapy'. Current conditions of the aforementioned combined modalities and the future perspectives are presented. The following subjects are covered: (1) tumor control - significance of the number of stem cells; (2) biological evaluation of chemo-radiotherapy with cisplatin; (3) clinical results and experience with combination of radiotherapy and radiosensitizers; (4) radiosensitization with hypoxic cell radiosensitizers - present status (5) hypoxic cell radiosensitizers - present status and problems from the viewpoint of clinical radiotherapy; (6) thermal radiosensitization in vitro and its implications for radiotherapy; (7) clinical assessment of thermoradiotherapy for breast cancer and cancer of the urinary bladder; (8) interactions of radiation and biological response modifiers in the treatment of malignant tumor; (9) improvement in the effects of radiation therapy with biological response modifiers. (N.K.)

HIV-1 Tat depresses DNA-PKCS expression and DNA repair, and sensitizes cells to ionizing radiation

International Nuclear Information System (INIS)

Sun Yi; Huang Yuechen; Xu Qinzhi; Wang Huiping; Bai Bei; Sui Jianli; Zhou Pingkun

2006-01-01

Purpose There is accumulating evidence that cancer patients with human immmunodeficiency virus-1/acquired immunodeficency syndrome (HIV-1/AIDS) have more severe tissue reactions and often develop cutaneous toxic effects when subjected to radiotherapy. Here we explored the effects of the HIV-1 Tat protein on cellular responses to ionizing radiation. Methods and Materials Two Tat-expressing cell lines, TT2 and TE671-Tat, were derived from human rhabdomyosarcoma cells by transfecting with the HIV-1 tat gene. Radiosensitivity was determined using colony-forming ability. Gene expression was assessed by cDNA microarray and immunohybridization. The Comet assay and γ-H2AX foci were use to detect DNA double-strand breaks (DSBs) and repair. Radiation-induced cell cycle changes were detected by flow cytometry. Results The radiosensitivity of TT2 and TE671-Tat cells was significantly increased as compared with parental TE671 cells or the control TE671-pCI cells. Tat also increased proliferation activity. The comet assay and γH2AX foci detection revealed a decreased capacity to repair radiation-induced DNA DSBs in Tat-expressing cells. Microarray assay demonstrated that the DNA repair gene DNA-PKcs, and cell cycle-related genes Cdc20, Cdc25C, KIF2C and CTS1 were downregulated in Tat-expressing cells. Depression of DNA-PKcs in Tat-expressing cells was further confirmed by RT-PCR and immuno-hybridization analysis. Tat-expressing cells exhibited a prolonged S phase arrest after 4 Gy γ-irradiation, and a noticeable delay in the initiation and elimination of radiation-induced G 2 /M arrest as compared with parental cells. In addition, the G 2 /M arrest was incomplete in TT2 cells. Moreover, HIV-1 Tat resulted in a constitutive overexpression of cyclin B1 protein. Conclusion HIV-1 Tat protein sensitizes cells to ionizing radiation via depressing DNA repair and dysregulating cell cycle checkpoints. These observations provide new insight into the increased tissue reactions of AIDS

Multiparametric assessment of radiation effects for the individual radiation sensitivity estimation

International Nuclear Information System (INIS)

2006-01-01

The effects of low dose irradiation are highly relevant for radiation protection in the public. The sensitivity to clastogenic and tumorigenic effects of ionizing radiation (IR) varies considerably amongst individuals. Examples for genetically determined enhanced sensitivity are well known in some hereditary diseases: patients with chromosomal instability syndromes, Ataxia telangiectasia (A-T), Nijmegen Breakage Syndrome (NBS) and Bloom Syndrome (BS) show strongly enhanced sensitivity towards IR, severe immunodeficiencies, and a high incidence for developing leukemias and lymphomas. This obvious coincidence of enhanced radiosensitivity and tumor risk, and the frequently observed enhanced radiosensitivity of genetically non-defined tumor patients indicate that tumor patients may constitute a subpopulation with enriched genetical predisposition for enhanced radiosensitivity. Furthermore, a subpopulation of radiosensitive individuals may be part of the probably inconspicuous total population. For example, individuals heterozygous for the above mentioned genes (and possibly some other genes) show enhanced radiosensitivity if compared with the normal population. In general, heterozygous carriers of those hereditary deficiencies are clinically inconspicuous, but due an haploinsufficiency their tumour risk may be enhanced. This has been shown for mice carrying an heterozygous Nbs1 mutation (J.-Q. Wang, Lyon, pers. Communication). Our findings concerning enhanced radiation-induced chromosomal aberrations in heterozygous Nbs1 cell lines support this notion. The identification of high risk groups with enhanced radiosensitivity is therefore an important task for radioprotection. This project aimed at establishing a procedure which allows to test various cellular parameters as indicators for effects of radiation. A standard protocol for the isolation and cryoconservation of primary blood cells was developed. DNA repair analysis (Comet Assay) and radiation-induced apoptosis

Ionizing radiation sensitivity of DNA polymerase lambda-deficient cells.

NARCIS (Netherlands)

Vermeulen, C.; Bertocci, B.; Begg, A.C.; Vens, C.

2007-01-01

Ionizing radiation induces a diverse spectrum of DNA lesions, including strand breaks and oxidized bases. In mammalian cells, ionizing radiation-induced lesions are targets of non-homologous end joining, homologous recombination, and base excision repair. In vitro assays show a potential involvement

TERRA Expression Levels Do Not Correlate With Telomere Length and Radiation Sensitivity in Human Cancer Cell Lines

Directory of Open Access Journals (Sweden)

Alexandra eSmirnova

2013-05-01

Full Text Available Mammalian telomeres are transcribed into long non-coding telomeric RNA molecules (TERRA that seem to play a role in the maintenance of telomere stability. In human cells, CpG island promoters drive TERRA transcription and are regulated by methylation. It was suggested that the amount of TERRA may be related to telomere length. To test this hypothesis we measured telomere length and TERRA levels in single clones isolated from five human cell lines: HeLa (cervical carcinoma, BRC-230 (breast cancer, AKG and GK2 (gastric cancers and GM847 (SV40 immortalized skin fibroblasts. We observed great clonal heterogeneity both in TRF (Terminal Restriction Fragment length and in TERRA levels. However, these two parameters did not correlate with each other. Moreover, cell survival to γ-rays did not show a significant variation among the clones, suggesting that, in this cellular system, the intra-population variability in telomere length and TERRA levels does not influence sensitivity to ionizing radiation. This conclusion was supported by the observation that in a cell line in which telomeres were greatly elongated by the ectopic expression of telomerase, TERRA expression levels and radiation sensitivity were similar to the parental HeLa cell line.

Changes in antibiotic sensitivity and cell surface hydrophobicity in Escherichia coli injured by heating, freezing, drying or gamma radiation

International Nuclear Information System (INIS)

Mackey, B.M.

1983-01-01

Escherichia coli cells exposed to mild heating, freezing and thawing, drying or γ-radiation were sensitised to hydrophobic antibiotics and sodium deoxycholate but not to small hydrophilic antibiotics. These stress treatments also caused increases in cell surface hydrophobicity broadly reflecting the degree of sensitivity to hydrophobic antibiotics. (Auth.)

Modification of radiation sensitivity by edaravone

International Nuclear Information System (INIS)

Sasano, Nakashi; Enomoto, Atsushi; Miyagawa, Kiyoshi; Hosoi, Yoshio; Nakagawa, Keiichi

2009-01-01

Studied was the effect of edaravone (E), a clinical therapeutic drug for brain infarction possessing properties of free radical scavenger, on apoptosis in vitro. Human T-cell leukemic MOLT-4 cells and p53-knockdown MOLT-4 cells which overexpressing short hairpin type p53 by siRNA treatment were X-irradiated by Shimadzu Pantak HF 350 machine at 135-140 cGy/min for 2-5 Gy in total, in the presence of E. Cell death was estimated by dye-exclusion, apoptosis by EPICS flow cytometry, cellular reactive oxygen species by chloromethyl-2',7'-dichlorodihydrofluoresein diacetate (CM-H 2 -DCFDA) fluorometry, and p53-related protein expression by Western blotting. E was found to have a radio-protective effect on cells at high concentrations (e.g., 2.7 and 3 mg/mL, 2Gy) and radio-sensitizing action at low concentrations (e.g., 0.15-1.5 mg/mL). Clinical plasma levels of E have been reportedly far lower than the concentrations in this experiment: ideally, E can sensitize tumor cells to radiation and protect normal cells from. (K.T.)

DNA-nuclear matrix interactions and ionizing radiation sensitivity

International Nuclear Information System (INIS)

Schwartz, J.L.; Vaughan, A.T.M.

1993-01-01

The association between inherent ionizing radiation sensitivity and DNA supercoil unwinding in mammalian cells suggests that the organization of the DNA in chromosomes plays an important role in radiation responses. In this paper, a model is proposed which suggests that these DNA unwinding alterations reflect differences in the attachment of DNA to the nuclear matrix. In radioresistant cells, the MAR structure might exist in a more stable, open configuration, limiting DNA unwinding following strand break induction and influencing the rate and nature of DNA double-strand break rejoining

The influence of oxygen on the induction of radiation damage in DNA in mammalian cells after sensitization by intracellular glutathione depletion

International Nuclear Information System (INIS)

Schans, G.P. van der; Vos, O.; Roos-Verheij, W.S.D.; Lohman, P.H.M.

1986-05-01

Treatment of mammalian cells with buthionine sulphoximine (BSO) or diethyl maleate (DEM) results in a decrease in the intracellular GSH (glutathione) and NPSH (non-protein-bound SH) levels. The effect of depletion of GSH and NPSH on radiosensitivity was studied in relation to the concentration of oxygen during irradiation. Single- and double-strand DNA breaks (ssb and dsb) and cell killing were used as criteria for radiation damage. Under aerobic conditions, BSO and DEM treatment gave a small sensitization of 10-20% for the 3 types of radiation damage. Also under severely hypoxic conditions (0.01 μM oxygen in the medium) the sensitizing effect of both compounds on the induction of ssb and dsb and on cell killing was small (0-30%). At somewhat higher concentrations of oxygen (0.5-10 μM) however, the sensitization amounted to about 90% for the induction of ssb and dsb and about 50% for cell killing. These results strengthen the widely accepted idea that intracellular SH-compounds compete with oxygen and other electron-affinic radiosensitizers with respect to reaction with radiation-induced damage, thus preventing the fixation of DNA damages by oxygen. These results imply that the extent to which SH-compounds affect the radiosensitivity of cells in vivo depends strongly on the local concentration of oxygen. (Auth.)

Enhanced sensitivity of the RET proto-oncogene to ionizing radiation in vitro.

Science.gov (United States)

Volpato, Claudia Béu; Martínez-Alfaro, Minerva; Corvi, Raffaella; Gabus, Coralie; Sauvaigo, Sylvie; Ferrari, Pietro; Bonora, Elena; De Grandi, Alessandro; Romeo, Giovanni

2008-11-01

Exposure to ionizing radiation is a well-known risk factor for a number of human cancers, including leukemia and thyroid cancer. It has been known for a long time that exposure of cells to radiation results in extensive DNA damage; however, a small number of studies have tried to explain the mechanisms of radiation-induced carcinogenesis. The high prevalence of RET/PTC rearrangements in patients who have received external radiation, and the evidence of in vitro induction of RET rearrangements in human cells, suggest an enhanced sensitivity of the RET genomic region to damage by ionizing radiation. To assess whether RET is indeed more sensitive to radiations than other genomic regions, we used a COMET assay coupled with fluorescence in situ hybridization, which allows the measurement of DNA fragmentation in defined genomic regions of single cells. We compared the initial DNA damage of the genomic regions of RET, CXCL12/SDF1, ABL, MYC, PLA2G2A, p53, and JAK2 induced by ionizing radiation in both a lymphoblastoid and a fetal thyroid cell line. In both cell lines, RET fragmentation was significantly higher than in other genomic regions. Moreover, a differential distribution of signals within the COMET was associated with a higher percentage of RET fragments in the tail. RET was more susceptible to fragmentation in the thyroid-derived cells than in lymphoblasts. This enhanced susceptibility of RET to ionizing radiation suggests the possibility of using it as a radiation exposure marker.

Functional inhibition of Ubiquitin conjugating Enzyme (UBE2C) reduces proliferation and sensitizes cervical and breast cancer cells to radiation, doxorubicin, tamoxifen and letrozole

International Nuclear Information System (INIS)

Bose, Mayil Vahanan; Rawat, Akhilesh; Gopisetty, Gopal; Thangarajan, Rajkumar; Ganesharaja, Selvaluxmy

2014-01-01

Cervical cancer is the second most common cancer in women, worldwide. About 80% of cervical cancer cases occur in developing countries. Breast cancer has overtaken cervical cancer in most of the urban centers in India. In recent years, interest in the role of Ubiquitin conjugating Enzyme E2C (UBE2C) in cancer has shown a dramatic increase. Several studies have reported UBE2C as a potential oncogene and therapeutic target. The objective of the study was to elucidate radiation and chemo-sensitivity in response to functional inhibition of UBE2C in cervical and breast cancer cell lines. Taqman Real time PCR was performed to measure UBE2C levels in cervical and breast cancer cell lines. A dominant negative form of UBE2C (DN-UBE2C) was used to functionally inhibit wild type UBE2C. Cell proliferation and anchorage independent growth were measured by colorimetric assay and soft agar assay respectively. Radiation and chemo response of cell lines were assessed by colorimetric assay and clonogenic assay. Difference in sensitivity to radiation was observed among the cervical cancer cell lines studied. The growth rate of SiHa and HeLa transfected with DN- UBE2C was significantly reduced compared to vector control. Further, DN-UBE2C mediated radio-sensitivity was correlated with a significant decrease in resistance to radiation by SiHa and HeLa cells after transfection when compared to control cultures. Similarly, both the growth rate and the anchorage independent growth of MCF7 and MDAMB231 cells transfected with DN-UBE2C were significantly reduced compared to cells transfected with vector alone. MCF7 and MDAMB231 cells expressing DN-UBE2C were significantly more sensitive to different doses of radiation and doxorubicin compared to controls. In addition, DN-UBE2C transfected MCF7 cells were more sensitive to inhibition by tamoxifen and letrozole compared to vector controls. These results suggest that UBE2C can be used as a potential therapeutic target for cervical and breast

Radiation and/or hyperthermia sensitivity of human melanoma cells grown for several days in media with reduced pH

International Nuclear Information System (INIS)

Zoelzer, F.; Streffer, C.

1999-01-01

MeWo cells were used throughout. Cells were incubated for 0, 3 or 6 days in media with pH 6.5, 6.7, 6.9, 7.1 or 7.3. The sensitivity against 250 kV X-rays and hyperthermia at 43 C were determined in the colony-forming assay. The intracellular pH was measured flow cytometrically using 5(and 6)-carboxyfluoroescein. Calibration curves were established with cells incubated in different buffers containing nigericin to equilibrate intra- and extracellular pH. Results: Cell growth was optimal with pH 7.3 and 7.1 in the medium, somewhat reduced at pH 6.9, and largely inhibited at pH 6.7 and 6.5. Radiation and/or hyperthermia sensitivities were noticeably increased after several days of incubation at reduced pH; the surviving fraction after 4 Gy and 1 h at 43 C either alone or in combination being a factor of 2 to 4 lower at pH 6.5 than at 7.3. These changes in sensitivity could not be correlated with changes in the intracellular pH. Cells seemed to be capable of regulating this parameter very well; the flow cytometric measurements revealed that the intracellular pH was 7.2±0.2 irrespective of the extracellular pH in the range considered here. Conclusions: In contrast to the almost generally accepted hypothesis that intracellular pH is decisive for the heat sensitivity, the human melanoma cells studied here became sensitive after a few days of incubation under acidic conditions without changes in the intracellular pH. Other factors seem to be influencing the cellular response to radiation and/or heat under chronically low pH. (orig./MG) [de

JNK inhibition sensitizes tumor cells to radiation-induced premature senescence via Bcl-2/ROS/DDR signaling pathway

International Nuclear Information System (INIS)

Lee, Jae Seon; Lee, Je Jung

2009-01-01

Premature senescence is considered as a cellular defense mechanism to prevent tumorigenesis. Although recent evidences demonstrate that c-Jun N-terminal kinase (JNK) is involved in the senescence process, the target and exact mechanism of JNK signaling in the regulation of cell proliferation has yet to be defined. In this study, we investigated the role of JNK in premature senescence and demonstrated JNK inhibition sensitized tumor cells to radiation-induced premature senescence

Sensitivity of clostridium acetobutylicum to oxygen and ionizing radiation

International Nuclear Information System (INIS)

Sozer, A.C.; Adler, H.I.; Machanoff, R.; Haney, S.

1984-01-01

The authors are studying the sensitivity of four strains of the obligate anaerobe, Clostridium acetobutylicum, to oxygen and ionizing radiation. Anaerobic bacteria are useful for such studies because of the absence of elaborate oxygen detoxification mechanisms that are found in aerobes. Their experiments make use of sterile membrane fragments from Escherichia coli that rapidly remove molecular oxygen from media and permit growth of anaerobes without the use of reducing agents or anaerobic chambers. Of the four strains examined for sensitivity to ionizing radiation under anaerobic conditions, one has an LD/sub 50/ of -- 25 krads and the others have an LD/sub 50/ of -- 7 krads. The radiation resistant strain is also relatively resistant to oxygen exposure. Sensitivity to oxygen was determined by diluting cells in buffer at 28 0 and bubbling with air. An exposure to air for 40 min induced only slight inactivation in the radiation resistant strain. All strains are capable of removing oxygen from complex media but there is no apparent correlation between this oxygen consuming reaction and inactivation by either oxygen or radiation

Oxygen-dependent sensitization of irradiated cells

International Nuclear Information System (INIS)

Ewing, D.; Powers, E.L.

1979-01-01

Attention is focused primarily on O 2 effects in three biological systems, all tested in suspension: bacterial spores, vegetative bacterial cells, and mammalian cells. Information from these systems shows that O 2 has more than one process through which it can act. Studies with bacterial spore suspensions provide clear evidence that multiple components to oxygen-dependent radiation sensitization exist. Studies with mammalian cell suspensions also show that at least two oxygen-dependent sensitization processes can be distinguished. Similar studies with vegetative bacteria in suspension have not resolved oxic sensitization into components. The roles of water-derived radicals in radiation sensitivity and, specifically, in sensitization by O 2 were examined. OH radicals are clearly implicated in damage in all three biological test systems. However, the specific roles proposed for OH radicals are different in these organisms. In bacterial spores, OH radical removal in itself does not protect in anoxia or in high concentrations of O 2 . OH radical removal over a limited intermediate range of O 2 concentrations will, however, protect. OH radical scavenging probably results in the formation of the actual protector. In bacteria, the supposition is that OH radical removal will protect both in anoxia and in the presence of O 2 . OH radicals probably react with a cellular target molecule and leave a radicalsite; this is the site which can then react with O 2 to cause damage; DNA is the likely cellular target. In mammalian cells, a reaction scheme, similar to that proposed for bacteria, has been suggested for O 2 -dependent sensitization

Research on Paramecium aurelia sensitivity factors to natural ionizing radiations

International Nuclear Information System (INIS)

Croute, F.; Soleilhavoup, J.P.; Gros, N.; Planel, H.

1976-01-01

Previous results have demonstrated that the proliferative activity of Paramecium aurelia is linked to the level of natural ionizing radiations since this activity is decreased under radiation protection (lead cell) and increased under chronic exposure to very low dose of 60 Co gamma rays. The results of this investigation indicate that cell sensitivity in spite of variations in natural irradiation levels can be isolated; they are called 'radioresistant' in opposition to 'radiosensitive' cells which present the other response. These characters are being retained for 9 months after the strains have been isolated. On the other hand, in the case of radiosensitive strains, it has been demonstrated that autogamy affected the cell response to background irradiation; no response at all occured on the very day when autogamy took place, but it reached a maximum level 8 days approximately after autogamy. Moreover, it has been proved that the catalase activity of Paramecium aurelia is higher than those already studied in other cell varieties. This great amount of catalase, which seems to vary with the age of cultures after autogamy, could act on Paramecium sensitivity to very low radiation doses [fr

Targeting DNA repair with PNKP inhibition sensitizes radioresistant prostate cancer cells to high LET radiation.

Directory of Open Access Journals (Sweden)

Pallavi Srivastava

Full Text Available High linear energy transfer (LET radiation or heavy ion such as carbon ion radiation is used as a method for advanced radiotherapy in the treatment of cancer. It has many advantages over the conventional photon based radiotherapy using Co-60 gamma or high energy X-rays from a Linear Accelerator. However, charged particle therapy is very costly. One way to reduce the cost as well as irradiation effects on normal cells is to reduce the dose of radiation by enhancing the radiation sensitivity through the use of a radiomodulator. PNKP (polynucleotide kinase/phosphatase is an enzyme which plays important role in the non-homologous end joining (NHEJ DNA repair pathway. It is expected that inhibition of PNKP activity may enhance the efficacy of the charged particle irradiation in the radioresistant prostate cancer cell line PC-3. To test this hypothesis, we investigated cellular radiosensitivity by clonogenic cell survival assay in PC-3 cells.12Carbon ion beam of62 MeVenergy (equivalent 5.16 MeV/nucleon and with an entrance LET of 287 kev/μm was used for the present study. Apoptotic parameters such as nuclear fragmentation and caspase-3 activity were measured by DAPI staining, nuclear ladder assay and colorimetric caspase-3method. Cell cycle arrest was determined by FACS analysis. Cell death was enhanced when carbon ion irradiation is combined with PNKPi (PNKP inhibitor to treat cells as compared to that seen for PNKPi untreated cells. A low concentration (10μM of PNKPi effectively radiosensitized the PC-3 cells in terms of reduction of dose in achieving the same survival fraction. PC-3 cells underwent significant apoptosis and cell cycle arrest too was enhanced at G2/M phase when carbon ion irradiation was combined with PNKPi treatment. Our findings suggest that combined treatment of carbon ion irradiation and PNKP inhibition could enhance cellular radiosensitivity in a radioresistant prostate cancer cell line PC-3. The synergistic effect of PNKPi

Contribution of autophagy inhibitor to radiation sensitization in nasopharyngeal carcinoma cells

International Nuclear Information System (INIS)

Zhou Zhirui; Zhu Xiaodong; Zhao Wei; Qu song; Pan Wenyan; Guo Ya; Su Fang; Li Xiaoyu

2012-01-01

Objective: To investigate the role of autophagy in radiation-induced death response of human nasopharyngeal carcinoma cells. Methods: MTT method was used to detect cell viability of CNE-2 cells in different time after irradiation. Clonogenic survival assay was used to evaluate the effect of autophagy inhibitor (chloroquine phosphate) and autophagy inductor (rapamycin) on radiosensitivity of nasopharyngeal carcinoma cells.Cell apoptosis was assessed by flow cytometry. The expressions of LC3 and P62 were measured with Western blot. Cell ultrastructural analysis was performed under an electron microscope.Results Irradiation with 10 Gy induced a massive accumulation of autophagosomes accompanied with up-regulation of LC3-Ⅱ expression in CNE-2 cells. Compared with radiation alone, chloroquine phosphate (CDP) enhanced radiosensitivity significantly by decreasing cell viability (F=25.88, P<0.05), autophagic ratio (F=105.15, P<0.05), and LC3-Ⅱ protein level (F=231.68, P<0.05), while up-regulating the expression of P62 (F=117.52, P<0.05). Inhibition of autophagy increased radiation-induced apoptosis (F=143.72, P<0.05). Rapamycin (RAPA) also significantly decreased cell viability, but increased autophagic ratio and LC3-Ⅱ protein level while down-regulated the expression of P62. Induction of autophagy increased radiation-induced apoptosis (F=167.32, P<0.05). Conclusions: Blockage of autophagy with CDP could enhance radiosensitivity in human nasopharyngeal carcinoma cells, suggesting that inhibition of autophagy could be used as an adjuvant treatment to nasopharyngeal carcinoma. (authors)

DNA-nuclear matrix interactions and ionizing radiation sensitivity

International Nuclear Information System (INIS)

Schwartz, J.L.; Chicago Univ., IL; Vaughan, A.T.M.

1993-01-01

The association between inherent ionizing radiation sensitivity and DNA supercoil unwinding in mammalian cells suggests that the DNA-nuclear matrix attachment region (MAR) plays an important role in radiation response. In radioresistant cells, the MAR structure may exist in a more stable, open configuration, limiting DNA unwinding following strand break induction and maintaining DNA ends in close proximity for more rapid and accurate rejoining. In addition, the open configuration at these matrix attachment sites may serve to facilitate rapid DNA processing of breaks by providing (1) sites for repair proteins to collect and (2) energy to drive enzymatic reactions

Modification of radiation sensitivity by edaravone

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Sasano, Nakashi; Enomoto, Atsushi; Miyagawa, Kiyoshi [Tokyo Univ., Graduate School of Medicine, Tokyo (Japan); Hosoi, Yoshio [Niigata Univ., School of Health Sciences, Niigata, Niigata (Japan); Nakagawa, Keiichi [Tokyo Univ., Hospital, Tokyo (Japan)

2009-03-15

Studied was the effect of edaravone (E), a clinical therapeutic drug for brain infarction possessing properties of free radical scavenger, on apoptosis in vitro. Human T-cell leukemic MOLT-4 cells and p53-knockdown MOLT-4 cells which overexpressing short hairpin type p53 by siRNA treatment were X-irradiated by Shimadzu Pantak HF 350 machine at 135-140 cGy/min for 2-5 Gy in total, in the presence of E. Cell death was estimated by dye-exclusion, apoptosis by EPICS flow cytometry, cellular reactive oxygen species by chloromethyl-2',7'-dichlorodihydrofluoresein diacetate (CM-H{sub 2}-DCFDA) fluorometry, and p53-related protein expression by Western blotting. E was found to have a radio-protective effect on cells at high concentrations (e.g., 2.7 and 3 mg/mL, 2Gy) and radio-sensitizing action at low concentrations (e.g., 0.15-1.5 mg/mL). Clinical plasma levels of E have been reportedly far lower than the concentrations in this experiment: ideally, E can sensitize tumor cells to radiation and protect normal cells from. (K.T.)

Cellular determinants of the inverse cross sensitivity of mouse lymphoma L5178Y cell lines to ionizing radiation and hydrogen peroxide

International Nuclear Information System (INIS)

Kruszewski, M.

1999-01-01

The pair of L5178Y sublines (LY-R and LY-S) is exceptional among mammalian cell lines because of their unique inverse cross-sensitivity to ionizing radiation and hydrogen peroxide. The high sensitivity of LY-S cells to ionizing radiation is reasonably explained by the impairment of DNA double strand breaks rejoining. Although the enzymatic defect of LY-S cells is not yet identified, the more pronounced effect of DNA-dependent protein kinase (DNA-PK) inhibitor (OK-1035) on DNA damage repair after 8 Gy x-irradiation in LY-R cells than in LY-S cells, suggests that LY-S cells may be defective in DNA-PK activity or in the other enzymatic activities downstream from DNA-PK. An additional feature is a higher protection of DNA against ionizing radiation by nuclear proteins in LY-R cells. These data support the concept that nuclear matrix organization may contribute to the cellular susceptibility to DNA damaging agents. Ionizing radiation-sensitive LY-S cells suffer also more DNA base damage than ionizing radiation-resistant LY-R cells. However, the repair rates of the γ-ray-induced DNA base damage in LY sublines are related neither to the initial amounts of the damaged bases nor to the lethal or mutagenic effects of ionizing radiation. In contrast, hydrogen peroxide (H 2 O 2 ) sensitive LY-R cells suffer more DNA base damage after H 2 O 2 treatment. This may be due to the lower activity of catalase and/or the lower level of glutathione and other monobromobimane-reactive thiols in LY-R cells than in LY-S cells. However, the main cause of LY-R cells' sensitivity to H 2 O 2 seems to be a higher iron ion content in these cells as compared to LY-S cells. A higher content of iron ions and a higher iron:copper ratio is found in isolated nuclei of LY-R cells than in those of LY-S cells. This is further confirmed by a higher ''labile iron'' pool in LY-R cells than in LY-S cells. Further evidence of different ions content in LY cells and its influence on nuclear matrix organization

At the Crossroads of Cancer Stem Cells, Radiation Biology, and Radiation Oncology.

Science.gov (United States)

Gerweck, Leo E; Wakimoto, Hiroaki

2016-03-01

Reports that a small subset of tumor cells initiate and sustain tumor growth, are resistant to radiation and drugs, and bear specific markers have led to an explosion of cancer stem cell research. These reports imply that the evaluation of therapeutic response by changes in tumor volume is misleading, as volume changes reflect the response of the sensitive rather than the resistant tumorigenic cell population. The reports further suggest that the marker-based selection of the tumor cell population will facilitate the development of radiation treatment schedules, sensitizers, and drugs that specifically target the resistant tumorigenic cells that give rise to treatment failure. This review presents evidence that contests the observations that cancer stem cell markers reliably identify the subset of tumor cells that sustain tumor growth and that the marker-identified population is radioresistant relative to the marker-negative cells. Experimental studies show that cells and tumors that survive large radiation doses are not more radioresistant than unirradiated cells and tumors, and also show that the intrinsic radiosensitivity of unsorted colony-forming tumor cells, in combination with the fraction of unsorted tumor cells that are tumor initiating, predicts tumor radiocurability. ©2016 American Association for Cancer Research.

Polo-like kinase 1 (PLK1) inhibition suppresses cell growth and enhances radiation sensitivity in medulloblastoma cells

International Nuclear Information System (INIS)

Harris, Peter S; Foreman, Nicholas K; Vibhakar, Rajeev; Venkataraman, Sujatha; Alimova, Irina; Birks, Diane K; Donson, Andrew M; Knipstein, Jeffrey; Dubuc, Adrian; Taylor, Michael D; Handler, Michael H

2012-01-01

Medulloblastoma is the most common malignant brain tumor in children and remains a therapeutic challenge due to its significant therapy-related morbidity. Polo-like kinase 1 (PLK1) is highly expressed in many cancers and regulates critical steps in mitotic progression. Recent studies suggest that targeting PLK1 with small molecule inhibitors is a promising approach to tumor therapy. We examined the expression of PLK1 mRNA in medulloblastoma tumor samples using microarray analysis. The impact of PLK1 on cell proliferation was evaluated by depleting expression with RNA interference (RNAi) or by inhibiting function with the small molecule inhibitor BI 2536. Colony formation studies were performed to examine the impact of BI 2536 on medulloblastoma cell radiosensitivity. In addition, the impact of depleting PLK1 mRNA on tumor-initiating cells was evaluated using tumor sphere assays. Analysis of gene expression in two independent cohorts revealed that PLK1 mRNA is overexpressed in some, but not all, medulloblastoma patient samples when compared to normal cerebellum. Inhibition of PLK1 by RNAi significantly decreased medulloblastoma cell proliferation and clonogenic potential and increased cell apoptosis. Similarly, a low nanomolar concentration of BI 2536, a small molecule inhibitor of PLK1, potently inhibited cell growth, strongly suppressed the colony-forming ability, and increased cellular apoptosis of medulloblastoma cells. Furthermore, BI 2536 pretreatment sensitized medulloblastoma cells to ionizing radiation. Inhibition of PLK1 impaired tumor sphere formation of medulloblastoma cells and decreased the expression of SRY (sex determining region Y)-box 2 (SOX2) mRNA in tumor spheres indicating a possible role in targeting tumor inititiating cells. Our data suggest that targeting PLK1 with small molecule inhibitors, in combination with radiation therapy, is a novel strategy in the treatment of medulloblastoma that warrants further investigation

Hypoxia Potentiates the Radiation-Sensitizing Effect of Olaparib in Human Non-Small Cell Lung Cancer Xenografts by Contextual Synthetic Lethality

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Jiang, Yanyan; Verbiest, Tom; Devery, Aoife M.; Bokobza, Sivan M.; Weber, Anika M.; Leszczynska, Katarzyna B.; Hammond, Ester M.; Ryan, Anderson J., E-mail: anderson.ryan@oncology.ox.ac.uk

2016-06-01

Purpose: Poly(ADP-ribose) polymerase (PARP) inhibitors potentiate radiation therapy in preclinical models of human non-small cell lung cancer (NSCLC) and other types of cancer. However, the mechanisms underlying radiosensitization in vivo are incompletely understood. Herein, we investigated the impact of hypoxia on radiosensitization by the PARP inhibitor olaparib in human NSCLC xenograft models. Methods and Materials: NSCLC Calu-6 and Calu-3 cells were irradiated in the presence of olaparib or vehicle under normoxic (21% O{sub 2}) or hypoxic (1% O{sub 2}) conditions. In vitro radiosensitivity was assessed by clonogenic survival assay and γH2AX foci assay. Established Calu-6 and Calu-3 subcutaneous xenografts were treated with olaparib (50 mg/kg, daily for 3 days), radiation (10 Gy), or both. Tumors (n=3/group) were collected 24 or 72 hours after the first treatment. Immunohistochemistry was performed to assess hypoxia (carbonic anhydrase IX [CA9]), vessels (CD31), DNA double strand breaks (DSB) (γH2AX), and apoptosis (cleaved caspase 3 [CC3]). The remaining xenografts (n=6/group) were monitored for tumor growth. Results: In vitro, olaparib showed a greater radiation-sensitizing effect in Calu-3 and Calu-6 cells in hypoxic conditions (1% O{sub 2}). In vivo, Calu-3 tumors were well-oxygenated, whereas Calu-6 tumors had extensive regions of hypoxia associated with down-regulation of the homologous recombination protein RAD51. Olaparib treatment increased unrepaired DNA DSB (P<.001) and apoptosis (P<.001) in hypoxic cells of Calu-6 tumors following radiation, whereas it had no significant effect on radiation-induced DNA damage response in nonhypoxic cells of Calu-6 tumors or in the tumor cells of well-oxygenated Calu-3 tumors. Consequently, olaparib significantly increased radiation-induced growth inhibition in Calu-6 tumors (P<.001) but not in Calu-3 tumors. Conclusions: Our data suggest that hypoxia potentiates the radiation-sensitizing effects of

Role of membrane Hsp70 in radiation sensitivity of tumor cells

International Nuclear Information System (INIS)

Murakami, Naoya; Kühnel, Annett; Schmid, Thomas E.; Ilicic, Katarina; Stangl, Stefan; Braun, Isabella S.; Gehrmann, Mathias; Molls, Michael; Itami, Jun; Multhoff, Gabriele

2015-01-01

The major stress-inducible heat shock protein 70 (Hsp70) is frequently overexpressed in the cytosol and integrated in the plasma membrane of tumor cells via lipid anchorage. Following stress such as non-lethal irradiation Hsp70 synthesis is up-regulated. Intracellular located Hsp70 is known to exert cytoprotective properties, however, less is known about membrane (m)Hsp70. Herein, we investigate the role of mHsp70 in the sensitivity towards irradiation in tumor sublines that differ in their cytosolic and/or mHsp70 levels. The isogenic human colon carcinoma sublines CX + with stable high and CX − with stable low expression of mHsp70 were generated by fluorescence activated cell sorting, the mouse mammary carcinoma sublines 4 T1 (4 T1 ctrl) and Hsp70 knock-down (4 T1 Hsp70 KD) were produced using the CRISPR/Cas9 system, and the Hsp70 down-regulation in human lung carcinoma sublines H1339 ctrl/H1339 HSF-1 KD and EPLC-272H ctrl/EPLC-272H HSF-1 KD was achieved by small interfering (si)RNA against Heat shock factor 1 (HSF-1). Cytosolic and mHsp70 was quantified by Western blot analysis/ELISA and flow cytometry; double strand breaks (DSBs) and apoptosis were measured by flow cytometry using antibodies against γH2AX and real-time PCR (RT-PCR) using primers and antibodies directed against apoptosis related genes; and radiation sensitivity was determined using clonogenic cell surviving assays. CX + /CX − tumor cells exhibited similar cytosolic but differed significantly in their mHsp70 levels, 4 T1 ctrl/4 T1 Hsp70 KD cells showed significant differences in their cytosolic and mHsp70 levels and H1339 ctrl/H1339 HSF-1 KD and EPLC-272H ctrl/EPLC-272H HSF-1 KD lung carcinoma cell sublines had similar mHsp70 but significantly different cytosolic Hsp70 levels. γH2AX was significantly up-regulated in irradiated CX − and 4 T1 Hsp70 KD with low basal mHsp70 levels, but not in their mHsp70 high expressing counterparts, irrespectively of their cytosolic Hsp70 content. After

Radioresistant DNA synthesis in cells of patients showing increased chromosomal sensitivity to ionizing radiation

International Nuclear Information System (INIS)

Barenfeld, L.S.; Pleskach, N.M.; Bildin, V.N.; Prokofjeva, V.V.; Mikhelson, V.M.

1986-01-01

The rate of DNA synthesis after γ-irradiation was studied either by analysis of the steady-state distribution of daughter [ 3 H]DNA in alkaline sucrose gradients or by direct assay of the amount of [ 3 H]thymidine incorporated into DNA of fibroblasts derived from a normal donor (LCH882) and from Down's syndrome (LCH944), Werner's syndrome (WS1LE) and xeroderma pigmentosum (XP2LE) patients with chromosomal sensitivity to ionizing radiation. Doses of γ-irradiation that markedly inhibited the rate of DNA synthesis in normal human cells caused almost no inhibition of DNA synthesis in the cells from the affected individuals. The radioresistant DNA synthesis in Down's syndrome cells was mainly due to a much lower inhibition of replicon initiation than that in normal cells; these cells were also more resistant to damage that inhibited replicon elongation. Our data suggest that radioresistant DNA synthesis may be an intrinsic feature of all genetic disorders showing increased radiosensitivity in terms of chromosome aberrations. (orig.)

A mutation (radA100) in Escherichia coli that selectively sensitizes cells grown in rich medium to X- or U.V.-radiation, or methyl methanesulphonate

International Nuclear Information System (INIS)

Diver, W.P.; Sargentini, N.J.; Smith, K.C.

1982-01-01

The radA100 mutant was isolated from Escherichia coli K-12 after mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine and selection for gamma radiation sensitivity. The radA100 mutation sensitized stationary phase cells to X-rays if they had been grown in glucose-supplemented rich medium, but not if they had been grown in nonsupplemented rich medium (indicating a defect in glucose-induced resistance). Similarly, logarithmic phase cells were sensitized to X-rays, U.V. radiation and methyl methanesulphonate if they had been grown in rich medium, but not if they had been grown in minimal medium (indicating a defect in medium-dependent resistance). Relative to the wild-type strain, the radA100 mutant was deficient in the repair of X-ray-induced DNA single-strand breaks when grown to logarithmic phase in rich medium, but not when grown in minimal medium. This is a novel mutation amongst the known DNA repair defects in that it did not sensitize logarithmic phase cells, grown in minimal medium, to either X- or U.V.-radiation. (author)

Ionizing radiation and nitric oxide donor sensitize Fas-induced apoptosis via up-regulation of Fas in human cervical cancer cells

International Nuclear Information System (INIS)

Park, In Chul; Woo, Sang Hyeok; Park, Myung Jin; Lee, Hyung Chahn; Lee Su Jae; Hong, Young Joon; Lee, Seung Hoon; Hong, Seok II; Rhee, Chang Hun

2004-01-01

Fas/CD95/Apo1 is a transmembrane receptor known to trigger apoptotic cell death in several cell types. In the present study, we showed that ionizing radiation (IR) and NO donor, S-nitroso-N-acetyl-penicillamine (SNAP), sensitized Fas-induced apoptotic cell death of HeLa human cervical cancers. Suboptimal dose of IR and SNAP up-regulated cell-surface Fas antigen, detected by FACScan using FITC-anti-Fas antibody. When combined with IR or SNAP, agonistic anti-Fas antibody CH-11 resulted in marked enhancement of apoptosis. This sensitization was completely abrogated by anti-Fas neutralizing antibody ZB4. During the IR and SNAP sensitized Fas-induced apoptosis, mitochondria permeabilization, cytochrome c release, and DNA fragmentation were detected. Furthermore, combined treatment of IR and SNAP additively up-regulated the surface Fas protein expression and sensitized Fas-induced apoptosis. Our finding demonstrate that sensitization of HeLa cervical cells to Fas-mediated apoptosis by IR and NO donor is most likely due to the up-regulation of Fas expression and also provides a means with which to sensitize tumors to the killing effects of cancer therapy via the Fas receptor

High-Density and Very-Low-Density Lipoprotein Have Opposing Roles in Regulating Tumor-Initiating Cells and Sensitivity to Radiation in Inflammatory Breast Cancer

Energy Technology Data Exchange (ETDEWEB)

Wolfe, Adam R. [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Morgan Welch Inflammatory Breast Cancer Research Program and Clinic, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Atkinson, Rachel L. [Morgan Welch Inflammatory Breast Cancer Research Program and Clinic, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Reddy, Jay P. [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Debeb, Bisrat G.; Larson, Richard; Li, Li [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Department of Clinical Cancer Prevention, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Masuda, Hiroko; Brewer, Takae [Department of Clinical Cancer Prevention, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Atkinson, Bradley J. [Department of Clinical Pharmacy Services, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Brewster, Abeena [Morgan Welch Inflammatory Breast Cancer Research Program and Clinic, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Ueno, Naoto T. [Department of Clinical Cancer Prevention, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Woodward, Wendy A., E-mail: wwoodward@mdanderson.org [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Department of Clinical Cancer Prevention, University of Texas MD Anderson Cancer Center, Houston, Texas (United States)

2015-04-01

Purpose: We previously demonstrated that cholesterol-lowering agents regulate radiation sensitivity of inflammatory breast cancer (IBC) cell lines in vitro and are associated with less radiation resistance among IBC patients who undergo postmastectomy radiation. We hypothesized that decreasing IBC cellular cholesterol induced by treatment with lipoproteins would increase radiation sensitivity. Here, we examined the impact of specific transporters of cholesterol (ie lipoproteins) on the responses of IBC cells to self-renewal and to radiation in vitro and on clinical outcomes in IBC patients. Methods and Materials: Two patient-derived IBC cell lines, SUM 149 and KPL4, were incubated with low-density lipoproteins (LDL), very-low-density lipoproteins (VLDL), or high-density lipoproteins (HDL) for 24 hours prior to irradiation (0-6 Gy) and mammosphere formation assay. Cholesterol panels were examined in a cohort of patients with primary IBC diagnosed between 1995 and 2011 at MD Anderson Cancer Center. Lipoprotein levels were then correlated to patient outcome, using the log rank statistical model, and examined in multivariate analysis using Cox regression. Results: VLDL increased and HDL decreased mammosphere formation compared to untreated SUM 149 and KPL4 cells. Survival curves showed enhancement of survival in both of the IBC cell lines when pretreated with VLDL and, conversely, radiation sensitization in all cell lines when pretreated with HDL. In IBC patients, higher VLDL values (>30 mg/dL) predicted a lower 5-year overall survival rate than normal values (hazard ratio [HR] = 1.9 [95% confidence interval [CI]: 1.05-3.45], P=.035). Lower-than-normal patient HDL values (<60 mg/dL) predicted a lower 5-year overall survival rate than values higher than 60 mg/dL (HR = 3.21 [95% CI: 1.25-8.27], P=.015). Conclusions: This study discovered a relationship among the plasma levels of lipoproteins, overall patient response, and radiation resistance in IBC patients

High-Density and Very-Low-Density Lipoprotein Have Opposing Roles in Regulating Tumor-Initiating Cells and Sensitivity to Radiation in Inflammatory Breast Cancer

International Nuclear Information System (INIS)

Wolfe, Adam R.; Atkinson, Rachel L.; Reddy, Jay P.; Debeb, Bisrat G.; Larson, Richard; Li, Li; Masuda, Hiroko; Brewer, Takae; Atkinson, Bradley J.; Brewster, Abeena; Ueno, Naoto T.; Woodward, Wendy A.

2015-01-01

Purpose: We previously demonstrated that cholesterol-lowering agents regulate radiation sensitivity of inflammatory breast cancer (IBC) cell lines in vitro and are associated with less radiation resistance among IBC patients who undergo postmastectomy radiation. We hypothesized that decreasing IBC cellular cholesterol induced by treatment with lipoproteins would increase radiation sensitivity. Here, we examined the impact of specific transporters of cholesterol (ie lipoproteins) on the responses of IBC cells to self-renewal and to radiation in vitro and on clinical outcomes in IBC patients. Methods and Materials: Two patient-derived IBC cell lines, SUM 149 and KPL4, were incubated with low-density lipoproteins (LDL), very-low-density lipoproteins (VLDL), or high-density lipoproteins (HDL) for 24 hours prior to irradiation (0-6 Gy) and mammosphere formation assay. Cholesterol panels were examined in a cohort of patients with primary IBC diagnosed between 1995 and 2011 at MD Anderson Cancer Center. Lipoprotein levels were then correlated to patient outcome, using the log rank statistical model, and examined in multivariate analysis using Cox regression. Results: VLDL increased and HDL decreased mammosphere formation compared to untreated SUM 149 and KPL4 cells. Survival curves showed enhancement of survival in both of the IBC cell lines when pretreated with VLDL and, conversely, radiation sensitization in all cell lines when pretreated with HDL. In IBC patients, higher VLDL values (>30 mg/dL) predicted a lower 5-year overall survival rate than normal values (hazard ratio [HR] = 1.9 [95% confidence interval [CI]: 1.05-3.45], P=.035). Lower-than-normal patient HDL values (<60 mg/dL) predicted a lower 5-year overall survival rate than values higher than 60 mg/dL (HR = 3.21 [95% CI: 1.25-8.27], P=.015). Conclusions: This study discovered a relationship among the plasma levels of lipoproteins, overall patient response, and radiation resistance in IBC patients

Sensitivity to low-dose radiation in radiosensitive ''wasted'' mice

International Nuclear Information System (INIS)

Paunesku, T.; Protic, M.; Woloschak, G. E.

1999-01-01

Mice homozygous for the autosomal recessive wasted mutation (wst/wst) have abnormalities in T-lymphocytes and in the anterior motor neuron cells of the spinal cord, leading to sensitivity to low doses of ionizing radiation, hind limb paralysis, and immunodeficiency. This defect results in a failure to gain weight by 20 days and death at 28 days of age. The wasted mutation (previously mapped to mouse chromosome 2) is shown to be a 3-bp deletion in a T-cell-specific (and perhaps motor-neuron-specific) regulatory region (promoter) of the proliferating cell nuclear antigen (PCNA) gene on mouse chromosome 2. A regulatory element is also shown to be important in PCNA expression in T-lymphocytes and motor neuron cells afflicted by the 3-bp deletion in the PCNA promoter. The model is as follows: Absence of PCNA expression in the thymuses (and motor neurons) of wasted mice causes cellular apoptosis; this absence of expression is mediated by a positive transactor that can bind to the wild-type but not the wasted mutant PCNA promoter; the bound protein induces late expression of PCNA in T-lymphocytes and prevents onset of radiation sensitivity in the cells

DIP and DIP + 2 as glutathione oxidants and radiation sensitizers in cultured Chinese hamster cells

International Nuclear Information System (INIS)

Harris, J.W.; Power, J.A.; Kosower, N.S.; Kosower, E.M.

1975-01-01

Two diamide analogues, diazene dicarboxylic acid bis (N'-methyl-piperazide) or DIP, and its bis-N'-methyl iodide salt, or DIP + 2, were tested for their ability to penetrate cultured Chinese hamster cells and oxidize intracellular glutathione. DIP penetrated the cells at a reasonable rate at 18 0 C, 160 nmoles being required to oxidize the endogenous glutathione of 2 x 10 6 cells, but it penetrated very slowly at 0 0 C. DIP + 2 did not effectively oxidize glutathione in Chinese hamster cells, possibly because it did not enter the cels. DIP became toxic after about 10 min of exposure, but its toxicity could be moderated by using anoxic conditions. DIP, but not DIP + 2, sensitized anoxic Chinese hamster cells to X-radiation by a factor of 1.5, an effect that was due entirely to removal of the shoulder from the survival curve. (author)

Study on intraoperative radiotherapy applying hyperthermia together with radiation sensitizers for progressive local carcinoma

Energy Technology Data Exchange (ETDEWEB)

Abe, M; Takahashi, M; Ono, K; Hiraoka, M [Kyoto Univ. (Japan). Faculty of Medicine

1980-08-01

Intraoperative radiotherapy for gastric cancer, colonic cancer, pancreatic cancer, cancer of the biliary tract, prostatic carcinoma, cerebral tumor, tumor of soft tissues, and osteosarcoma and its clinical results were described. Basic and clinical studies on effects of both hyperthermia and radiation sensitizers to elevate radiation sensitivity were also described, because effects of intraoperative radiotherapy were raised by applying hyperthermia and hypoxic cell sensitizers.

Tumor Cells Surviving Exposure to Proton or Photon Radiation Share a Common Immunogenic Modulation Signature, Rendering Them More Sensitive to T Cell–Mediated Killing

Energy Technology Data Exchange (ETDEWEB)

Gameiro, Sofia R.; Malamas, Anthony S. [Laboratory of Tumor Immunology and Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland (United States); Bernstein, Michael B. [Division of Radiation Oncology, M. D. Anderson Cancer Center, Houston, Texas (United States); Tsang, Kwong Y. [Laboratory of Tumor Immunology and Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland (United States); Vassantachart, April; Sahoo, Narayan; Tailor, Ramesh; Pidikiti, Rajesh [Division of Radiation Oncology, M. D. Anderson Cancer Center, Houston, Texas (United States); Guha, Chandan P. [Department of Radiation Oncology, Montefiore Medical Center, Bronx, New York (United States); Hahn, Stephen M.; Krishnan, Sunil [Division of Radiation Oncology, M. D. Anderson Cancer Center, Houston, Texas (United States); Hodge, James W., E-mail: jh241d@nih.gov [Laboratory of Tumor Immunology and Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland (United States)

2016-05-01

Purpose: To provide the foundation for combining immunotherapy to induce tumor antigen–specific T cells with proton radiation therapy to exploit the activity of those T cells. Methods and Materials: Using cell lines of tumors frequently treated with proton radiation, such as prostate, breast, lung, and chordoma, we examined the effect of proton radiation on the viability and induction of immunogenic modulation in tumor cells by flow cytometric and immunofluorescent analysis of surface phenotype and the functional immune consequences. Results: These studies show for the first time that (1) proton and photon radiation induced comparable up-regulation of surface molecules involved in immune recognition (histocompatibility leukocyte antigen, intercellular adhesion molecule 1, and the tumor-associated antigens carcinoembryonic antigen and mucin 1); (2) proton radiation mediated calreticulin cell-surface expression, increasing sensitivity to cytotoxic T-lymphocyte killing of tumor cells; and (3) cancer stem cells, which are resistant to the direct cytolytic activity of proton radiation, nonetheless up-regulated calreticulin after radiation in a manner similar to non-cancer stem cells. Conclusions: These findings offer a rationale for the use of proton radiation in combination with immunotherapy, including for patients who have failed radiation therapy alone or have limited treatment options.

Low and high linear energy transfer radiation sensitization of HCC cells by metformin

International Nuclear Information System (INIS)

Kim, Eun Ho; Jung, Won-Gyun; Kim, Mi-Sook; Cho, Chul-Koo; Jeong, Youn Kyoung; Jeong, Jae-Hoon

2014-01-01

The purpose of this study was to investigate the efficacy of metformin as a radiosensitizer for use in combination therapy for human hepatocellular carcinoma (HCC). Three human HCC cell lines (Huh7, HepG2, Hep3B) and a normal human hepatocyte cell line were treated with metformin alone or with radiation followed by metformin. In vitro tests were evaluated by clonogenic survival assay, FACS analysis, western blotting, immunofluorescence and comet assay. Metformin significantly enhanced radiation efficacy under high and low Linear Energy Transfer (LET) radiation conditions in vitro. In combination with radiation, metformin abrogated G2/M arrest and increased the cell population in the sub-G1 phase and the ROS level, ultimately increasing HCC cellular apoptosis. Metformin inhibits the repair of DNA damage caused by radiation. The radiosensitizing effects of metformin are much higher in neutron (high LET)-irradiated cell lines than in γ (low LET)-irradiated cell lines. Metformin only had a moderate effect in normal hepatocytes. Metformin enhances the radiosensitivity of HCC, suggesting it may have clinical utility in combination cancer treatment with high-LET radiation. (author)

Ionizing radiation induces stemness in cancer cells.

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Laura Ghisolfi

Full Text Available The cancer stem cell (CSC model posits the presence of a small number of CSCs in the heterogeneous cancer cell population that are ultimately responsible for tumor initiation, as well as cancer recurrence and metastasis. CSCs have been isolated from a variety of human cancers and are able to generate a hierarchical and heterogeneous cancer cell population. CSCs are also resistant to conventional chemo- and radio-therapies. Here we report that ionizing radiation can induce stem cell-like properties in heterogeneous cancer cells. Exposure of non-stem cancer cells to ionizing radiation enhanced spherogenesis, and this was accompanied by upregulation of the pluripotency genes Sox2 and Oct3/4. Knockdown of Sox2 or Oct3/4 inhibited radiation-induced spherogenesis and increased cellular sensitivity to radiation. These data demonstrate that ionizing radiation can activate stemness pathways in heterogeneous cancer cells, resulting in the enrichment of a CSC subpopulation with higher resistance to radiotherapy.

9-β-arabinofuranosyladenine preferentially sensitizes radioresistant squamous cell carcinoma cell lines to x-rays

International Nuclear Information System (INIS)

Heaton, D.

1992-06-01

The effect of 9-β-arabinofuranosyladenine (ara-A) on sensitivity to the deleterious effects of x-rays was studied in six squamous cell carcinoma cell lines. Three lines were relatively radioresistant, having D 0 values of 2.31 to 2.89 Gy, and the other three lines were relatively radiosensitive, having D 0 values of between 1.07 and 1.45 Gy. Ara-A (50 or 500 μM) was added to cultures 30 min prior to irradiation and removed 30 min after irradiation, and sensitivity was measured in terms of cell survival. The radiosensitizing effect of ara-A was very dependent on the inherent radiosensitivity of the tumor cell line. Fifty micromolar concentrations of ara-A sensitized only the two most radioresistant lines, SCC-12B.2 and JSQ-3. Five hundred micromolar concentrations of ara-A sensitized the more sensitive cell lines, SQ-20B and SQ-9G, but failed to have any effect on the radiation response of the two most sensitive cell lines, SQ-38 and SCC-61. Concentrations of ara-A as low as 10 μM were equally efficient in inhibiting DNA synthesis in all six cell lines. These results suggest that the target for the radiosensitizing effect of ara-A is probably related to the factor controlling the inherent radiosensitivity of human tumor cells. Therefore, ara-A might be useful in overcoming radiation resistance in vivo

9-{beta}-arabinofuranosyladenine preferentially sensitizes radioresistant squamous cell carcinoma cell lines to x-rays

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Heaton, D. [Rush Univ. Medical Center, Chicago, IL (United States). Therapeutic Radiology; Mustafi, R. [Chicago Univ., IL (United States). Dept. of Radiation and Cellular Oncology; Schwartz, J.L. [Chicago Univ., IL (United States). Dept. of Radiation and Cellular Oncology]|[Argonne National Lab., IL (United States)

1992-06-01

The effect of 9-{beta}-arabinofuranosyladenine (ara-A) on sensitivity to the deleterious effects of x-rays was studied in six squamous cell carcinoma cell lines. Three lines were relatively radioresistant, having D{sub 0} values of 2.31 to 2.89 Gy, and the other three lines were relatively radiosensitive, having D{sub 0} values of between 1.07 and 1.45 Gy. Ara-A (50 or 500 {mu}M) was added to cultures 30 min prior to irradiation and removed 30 min after irradiation, and sensitivity was measured in terms of cell survival. The radiosensitizing effect of ara-A was very dependent on the inherent radiosensitivity of the tumor cell line. Fifty micromolar concentrations of ara-A sensitized only the two most radioresistant lines, SCC-12B.2 and JSQ-3. Five hundred micromolar concentrations of ara-A sensitized the more sensitive cell lines, SQ-20B and SQ-9G, but failed to have any effect on the radiation response of the two most sensitive cell lines, SQ-38 and SCC-61. Concentrations of ara-A as low as 10 {mu}M were equally efficient in inhibiting DNA synthesis in all six cell lines. These results suggest that the target for the radiosensitizing effect of ara-A is probably related to the factor controlling the inherent radiosensitivity of human tumor cells. Therefore, ara-A might be useful in overcoming radiation resistance in vivo.

X-rays sensitive mammalian cell mutant

International Nuclear Information System (INIS)

Utsumi, Hiroshi

1982-01-01

A phenomenon that in x-ray-sensitive mammalian-cell mutants, cellular death due to x-ray radiation was not increased by caffeine, but on the contrary, the dead cells were resuscitated by it was discussed. The survival rate of mutant cells increased by caffein in a low concentration. This suggested that caffeine may have induced some mechanism to produce x-ray resistant mutant cells. Postirradiation treatment with caffeine increased considerably the survival rate of the mutant cells, and this suggested the existence of latent caffeine-sensitive potentially lethal damage repair system. This system, after a few hours, is thought to be substituted by caffeine-resistant repair system which is induced by caffeine, and this may be further substituted by x-ray-resistant repair system. The repair system was also induced by adenine. (Ueda, J.)

Chromatin status of apoptosis genes correlates with sensitivity to chemo-, immune- and radiation therapy in colorectal cancer cell lines.

Science.gov (United States)

Benard, Anne; Janssen, Connie M; van den Elsen, Peter J; van Eggermond, Marja C J A; Hoon, Dave S B; van de Velde, Cornelis J H; Kuppen, Peter J K

2014-12-01

The apoptosis pathway of programmed cell death is frequently deregulated in cancer. An intact apoptosis pathway is required for proper response to anti-cancer treatment. We investigated the chromatin status of key apoptosis genes in the apoptosis pathway in colorectal cancer cell lines in relation to apoptosis induced by chemo-, immune- or radiation therapy. Using chromatin immunoprecipitation (ChIP), we measured the presence of transcription-activating histone modifications H3Ac and H3K4me3 and silencing modifications H3K9me3 and H3K27me3 at the gene promoter regions of key apoptosis genes Bax, Bcl2, Caspase-9, Fas (CD95) and p53. Cell lines DLD1, SW620, Colo320, Caco2, Lovo and HT29 were treated with cisplatin, anti-Fas or radiation. The apoptotic response was measured by flow cytometry using propidium iodide and annexin V-FITC. The chromatin status of the apoptosis genes reflected the activation status of the intrinsic (Bax, Bcl2, Caspase-9 and p53) and extrinsic (Fas) pathways. An active intrinsic apoptotic pathway corresponded to sensitivity to cisplatin and radiation treatment of cell lines DLD1, SW620 and Colo320. An active Fas promoter corresponded to an active extrinsic apoptotic pathway in cell line DLD1. mRNA expression data correlated with the chromatin status of the apoptosis genes as measured by ChIP. In conclusion, the results presented in this study indicate that the balance between activating and silencing histone modifications, reflecting the chromatin status of apoptosis genes, can be used to predict the response of tumor cells to different anti-cancer therapies and could provide a novel target to sensitize tumors to obtain adequate treatment responses.

Snail-induced epithelial-to-mesenchymal transition of MCF-7 breast cancer cells: systems analysis of molecular changes and their effect on radiation and drug sensitivity

International Nuclear Information System (INIS)

Mezencev, Roman; Matyunina, Lilya V.; Jabbari, Neda; McDonald, John F.

2016-01-01

Epithelial-to-mesenchymal transition (EMT) has been associated with the acquisition of metastatic potential and the resistance of cancer cells to therapeutic treatments. MCF-7 breast cancer cells engineered to constitutively express the zinc-finger transcriptional repressor gene Snail (MCF-7-Snail cells) have been previously shown to display morphological and molecular changes characteristic of EMT. We report here the results of a comprehensive systems level molecular analysis of changes in global patterns of gene expression and levels of glutathione and reactive oxygen species (ROS) in MCF-7-Snail cells and the consequence of these changes on the sensitivity of cells to radiation treatment and therapeutic drugs. Snail-induced changes in global patterns of gene expression were identified by microarray profiling using the Affymetrix platform (U133 Plus 2.0). The resulting data were processed and analyzed by a variety of system level analytical methods. Levels of ROS and glutathione (GSH) were determined by fluorescent and luminescence assays, and nuclear levels of NF-κB protein were determined by an ELISA based method. The sensitivity of cells to ionizing radiation and anticancer drugs was determined using a resazurin-based cell cytotoxicity assay. Constitutive ectopic expression of Snail in epithelial-like, luminal A-type MCF-7 cells induced significant changes in the expression of >7600 genes including gene and miRNA regulators of EMT. Mesenchymal-like MCF-7-Snail cells acquired molecular profiles characteristic of triple-negative, claudin-low breast cancer cells, and displayed increased sensitivity to radiation treatment, and increased, decreased or no change in sensitivity to a variety of anticancer drugs. Elevated ROS levels in MCF-7-Snail cells were unexpectedly not positively correlated with NF-κB activity. Ectopic expression of Snail in MCF-7 cells resulted in morphological and molecular changes previously associated with EMT. The results underscore the

Atypical radiation response of SCID cells

Science.gov (United States)

Chawapun, Nisa

Murine SCID (severe combined immune deficiency) cells are well known for their defect in DNA double-strand break repair and in variable(diversity)joining [V(D)J] recombination due to a mutation in a catalytic subunit of DNA-dependent protein kinase (DNA-PKcs). As a consequence, scid cells are hypersensitive to ionizing radiation. The present study showed that asynchronous populations of scid cells were about two-fold more sensitive than Balb/c with respect to cell killing and the defect in scid cells was corrected by complementation with human chromosome 8. Analysis of the survival of synchronized populations as a function of the cell cycle revealed that while scid cells were hypersensitive in all cell cycle phases compared to wild-type cells, this hypersensitivity is even more pronounced in G1 phase. The hypersensitivity reduced as the cells progressed into S phase suggested that homologous recombination repair plays a role. The results imply that there are at least two pathways for the repair of DSB DNA, consistent with a model previously proposed by others. The scid cells were also more sensitive to UVC light (254 nm) killing as compared to wild type cells by clonogenic survival. Using a host cell reactivation (HCR) assay to study the nucleotide excision repair (NER) which is the major repair pathway for UV-photoproducts, the results showed that NER in scid cells was not as efficient as CB- 17. This suggests that DNA-PK is involved in NER as well as non-homologous end-joining (NHEJ) DSB repair which is responsible for ionizing radiation sensitivity in scid cells. Repair in scid cells was not totally absent as shown by low dose rate sparing of cell killing after exposure to 137Cs γ-rays at dose rate of 0.6 cGy/h, 1.36 cGy/h, 6 cGy/h as compared to high dose rate at 171 cGy/min, although this phenomenon could be explained partly by proliferation. However, for radiation induced transformation, no significant dose rate effect was seen. A plot of transformation

DNA conformation of Chinese hamster V79 cells and sensitivity to ionizing radiation

International Nuclear Information System (INIS)

Olive, P.L.; Hilton, J.; Durand, R.E.

1986-01-01

Chinese hamster V79 cells grown for 20 h in suspension culture form small clusters of cells (spheroids) which are more resistant to killing by ionizing radiation than V79 cells grown as monolayers. This resistance appears to be due to the greater capacity of cells grown in contact to repair radiation damage. Attempts to relate this ''contact effect'' to differences in DNA susceptibility or DNA repair capacity have provided conflicting results. Two techniques, alkaline sucrose gradient sedimentation and alkaline elution, show no difference in the amounts of radiation-induced DNA single-strand breakage or its repair between suspension or monolayer cells. However, using the alkali-unwinding assay, the rate of DNA unwinding is much slower for suspension cells than for monolayer cells. Interestingly, a decrease in salt concentration or in pH of the unwinding solution eliminates these differences in DNA unwinding kinetics. A fourth assay, sedimentation of nucleoids on neutral sucrose gradients, also shows a significant decrease in radiation damage produced in suspension compared to monolayer cultures. It is believed that this assay measures differences in DNA conformation (supercoiling) as well as differences in DNA strand breakage. We conclude from these four assays that the same number of DNA strand breaks/Gy is produced in monolayer and spheroid cells. However, changes in DNA conformation or packaging occur when cells are grown as spheroids, and these changes are responsible for reducing DNA damage by ionizing radiation

Comparison of two different techniques on the human lymphocytes morphology and sensitivity to gamma radiation

International Nuclear Information System (INIS)

Kol, R.

1985-02-01

The lymphocytes in the peripheral blood are divided into two main subclasses: T cells and B cells. These differ from each other in function and in their sensitivity to radiation. The effort to study which group is more sensitive to radiation has resulted in many contradictory results. In the present study we examined whether the methods that are used to separate the lymphocytes from the whole blood, before their separation into subclasses, have an effect on the cells and whether this might contribute to the contradictory results. Blood samples were taken from several normal donors and each sample was devided into two fractions. Lymphocytes in each fraction were separated by one of the two following methods: a) sedimentation of erythrocytes by gravitation; b) separation on Ficoll-Paque density gradient. For cells obtained by these two methods, the ultrastructure was examined by electron microscopy and their ability to incorporate radioactive thymidine was measured. Samples separated on Ficoll-Paque showed a subpopulation with morphological changes similar to those occuring in lymphocytes undergoing stimulation. Unstimulated cells separated on Ficoll-Paque showed greater sensitivity to radiation. The effect of gamma radiation on the capability of lymphocytes to undergo transformation in response to three mitogens; PHA, PWM and Con A was examined. Different mitogens stimulate different lymphocytes subpopulations. There was no difference between the two separation methods regarding the sensitivity to gamma radiation of stimulation by PAH and PWM. The transformation by Con A of lymphocytes separated on Ficoll-Paque was more radiosensitive. This could indicate that the separation by Ficoll-Paque density gradient causes a selective depletion of T lymphocytes that react with Con A and are considered more radioresistant. The use of different methods for separating lymphocytes from whole blood- each has a different influence on the cells- can contribute to contradictory

Models for cell survival with low LET radiation

International Nuclear Information System (INIS)

Payne, M.G.; Garrett, W.R.

1975-01-01

A model for cell survival under low LET irradiation was developed in which the cell is considered to have N 0 -independent sensitive sites, each of which can exist in either an undamaged state (state A) or one of two damaged states. Radiation can change the sensitive sites from the undamaged state to either of two damaged states. The first damaged state (state B) can either be repaired or be promoted on the second damaged state (state C), which is irreparable. The promotion from the first damaged state to the second can occur due to any of the following: (1) further radiation damage, (2) an abortive attempt to repair the site, or (3) the arrival at a part of the cell cycle where the damage is ''fixed.'' Subject to the further assumptions that radiation damage can occur either indirectly (i.e., through radiation products) or due to direct interaction, and that repair of the first damaged state is a one-step process, expressions can be derived for P(N/sub A/, N/sub B/,t) = probability that after time t a cell will have N/sub A/ sites in state A and N/sub B/ in state B. The problem of determining P(N/sub A/, N/sub B/, t) is formulated for arbitrary time dependences of the radiation field and of all rate coefficients. A large family of cell-survival models can be described by interpreting the sensitive sites in different ways and by making different choices of rate coefficients and of the combinations of numbers of sites in different states that will lead to cell death. (U.S.)

Cell lines derived from a Medaka radiation-sensitive mutant have defects in DNA double-strand break responses

International Nuclear Information System (INIS)

Hidaka, Masayuki; Oda, Shoji; Mitani, Hiroshi; Kuwahara, Yoshikazu; Fukumoto, Manabu

2010-01-01

It was reported that the radiation-sensitive Medaka mutant 'ric1' has a defect in the repair of DNA double-strand breaks (DSBs) induced by γ-rays during early embryogenesis. To study the cellular response of a ric1 mutant to ionizing radiation (IR), we established the mutant embryonic cell lines RIC1-e9, RIC1-e42, RIC1-e43. Following exposure to γ-irradiation, the DSBs in wild-type cells were repaired within 1 h, while those in RIC1 cells were not rejoined even after 2 h. Cell death was induced in the wild-type cells with cell fragmentation, but only a small proportion of the RIC1 cells underwent cell death, and without cell fragmentation. Although both wild-type and RIC1 cells showed mitotic inhibition immediately after γ-irradiation, cell division was much slower to resume in the wild-type cells (20 h versus 12 h). In both wild-type and RIC1 cells, Ser139 phosphorylated H2AX (γH2AX) foci were formed after γ-irradiation, however, the γH2AX foci disappeared more quickly in the RIC1 cell lines. These results suggest that the instability of γH2AX foci in RIC1 cells cause an aberration of the DNA damage response. As RIC1 cultured cells showed similar defective DNA repair as ric1 embryos and RIC1 cells revealed defective cell death and cell cycle checkpoint, they are useful for investigating DNA damage responses in vitro. (author)

SEM probe of IC radiation sensitivity

Science.gov (United States)

Gauthier, M. K.; Stanley, A. G.

1979-01-01

Scanning Electron Microscope (SEM) used to irradiate single integrated circuit (IC) subcomponent to test for radiation sensitivity can localize area of IC less than .03 by .03 mm for determination of exact location of radiation sensitive section.

Fibulin-3 negatively regulates ALDH1 via c-MET suppression and increases γ-radiation-induced sensitivity in some pancreatic cancer cell lines

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Kim, In-Gyu, E-mail: igkim@kaeri.re.kr [Department of Radiation Biology, Environmental Radiation Research Group, Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Department of Radiation Biotechnology and Applied Radioisotope, Korea University of Science and Technology (UST), 989-111 Daedeok-daero, Yusong-gu, Daejeon 305-353 (Korea, Republic of); Lee, Jae-Ha [Department of Radiation Biology, Environmental Radiation Research Group, Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Department of Radiation Biotechnology and Applied Radioisotope, Korea University of Science and Technology (UST), 989-111 Daedeok-daero, Yusong-gu, Daejeon 305-353 (Korea, Republic of); Kim, Seo-Yoen; Kim, Jeong-Yul [Department of Radiation Biology, Environmental Radiation Research Group, Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Cho, Eun-Wie [Epigenomics Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon 305-806 (Korea, Republic of)

2014-11-21

Highlights: • FBLN-3 gene was poorly expressed in some pancreatic cancer lines. • FBLN-3 promoter region was highly methylated in some pancreatic cancer cell lines. • FBLN-3 inhibited c-MET activation and expression and reduced cellular level of ALDH1. • FBLN-3/c-Met/ALDH1 axis modulates stemness and EMT in pancreatic cancer cells. - Abstract: Fibulin-3 (FBLN-3) has been postulated to be either a tumor suppressor or promoter depending on the cell type, and hypermethylation of the FBLN-3 promoter is often associated with human disease, especially cancer. We report that the promoter region of the FBLN-3 was significantly methylated (>95%) in some pancreatic cancer cell lines and thus FBLN-3 was poorly expressed in pancreatic cancer cell lines such as AsPC-1 and MiaPaCa-2. FBLN-3 overexpression significantly down-regulated the cellular level of c-MET and inhibited hepatocyte growth factor-induced c-MET activation, which were closely associated with γ-radiation resistance of cancer cells. Moreover, we also showed that c-MET suppression or inactivation decreased the cellular level of ALDH1 isozymes (ALDH1A1 or ALDH1A3), which serve as cancer stem cell markers, and subsequently induced inhibition of cell growth in pancreatic cancer cells. Therefore, forced overexpression of FBLN-3 sensitized cells to cytotoxic agents such as γ-radiation and strongly inhibited the stemness and epithelial to mesenchymal transition (EMT) property of pancreatic cancer cells. On the other hand, if FBLN3 was suppressed in FBLN-3-expressing BxPC3 cells, the results were opposite. This study provides the first demonstration that the FBLN-3/c-MET/ALDH1 axis in pancreatic cancer cells partially modulates stemness and EMT as well as sensitization of cells to the detrimental effects of γ-radiation.

Fibulin-3 negatively regulates ALDH1 via c-MET suppression and increases γ-radiation-induced sensitivity in some pancreatic cancer cell lines

International Nuclear Information System (INIS)

Kim, In-Gyu; Lee, Jae-Ha; Kim, Seo-Yoen; Kim, Jeong-Yul; Cho, Eun-Wie

2014-01-01

Highlights: • FBLN-3 gene was poorly expressed in some pancreatic cancer lines. • FBLN-3 promoter region was highly methylated in some pancreatic cancer cell lines. • FBLN-3 inhibited c-MET activation and expression and reduced cellular level of ALDH1. • FBLN-3/c-Met/ALDH1 axis modulates stemness and EMT in pancreatic cancer cells. - Abstract: Fibulin-3 (FBLN-3) has been postulated to be either a tumor suppressor or promoter depending on the cell type, and hypermethylation of the FBLN-3 promoter is often associated with human disease, especially cancer. We report that the promoter region of the FBLN-3 was significantly methylated (>95%) in some pancreatic cancer cell lines and thus FBLN-3 was poorly expressed in pancreatic cancer cell lines such as AsPC-1 and MiaPaCa-2. FBLN-3 overexpression significantly down-regulated the cellular level of c-MET and inhibited hepatocyte growth factor-induced c-MET activation, which were closely associated with γ-radiation resistance of cancer cells. Moreover, we also showed that c-MET suppression or inactivation decreased the cellular level of ALDH1 isozymes (ALDH1A1 or ALDH1A3), which serve as cancer stem cell markers, and subsequently induced inhibition of cell growth in pancreatic cancer cells. Therefore, forced overexpression of FBLN-3 sensitized cells to cytotoxic agents such as γ-radiation and strongly inhibited the stemness and epithelial to mesenchymal transition (EMT) property of pancreatic cancer cells. On the other hand, if FBLN3 was suppressed in FBLN-3-expressing BxPC3 cells, the results were opposite. This study provides the first demonstration that the FBLN-3/c-MET/ALDH1 axis in pancreatic cancer cells partially modulates stemness and EMT as well as sensitization of cells to the detrimental effects of γ-radiation

Clinical evaluation of hypoxic cell sensitizer (Misonidazole)

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Asakawa, Hiroshi (Miyagi Prefectural Adult Disease Center, Natori (Japan)); Watarai, Jiro; Hoshino, Toshiaki

1984-06-01

Clinical effectiveness and toxicity of Misonidazole were analyzed and discussed in 22 cases of carcinoma of uterine cervix, 17 cases of esophageal cancer and 11 with other malignancies treated by radiation. By clinical and histologic examination in the controlled trial, it was shown that radiation response of tumor was slightly sensitized in the treated group with this drug, compared with that in the control group. It was confirmed that there was no significant difference between radiation response of tumor in both groups. Peripheral neuropathy was a complication in 10% and toxicodermatitis in 12% even if the total dose administered was below 10 g/m/sup 2/. From these results, it was strongly suggested that this drug is not suitable in combination with simple fractionated irradiation as a hypoxic cell sensitizer.

Radiation-sensitive material and method of recording information upon radiation-sensitive material

International Nuclear Information System (INIS)

Petrov, V.V.; Krjuchin, A.A.

1981-01-01

The invention can be employed for recording binary information in memory units of electronic computers, in video-recording equipment, laser recording devices and other recording means. The proposed radiation-sensitive material comprises a metallic layer made of silver, or copper, or nickel, or thallium, or alloy thereof, an inorganic material layer made of arsenic chalcogenide, or antimony chalcogenide, or bismuth chalcogenide, and a separation layer disposed between the metallic layer and the inorganic material layer made of a material which is inert relative to said layers, which separation layer has a thickness sufficient for preventing interaction between the metallic layer and the inorganic material layer when the radiation-sensitive materials is exposed to electromagnetic or corpuscular radiation having a power density lower than a threshold value required for the breakdown of the separation layer in the area exposed to radiation. The separation layer can be made from As, Sb, Si or Ge or their oxides, metallic oxides of e.g. Al, Ti, V or Fe, or from polyorganosiloxane films. (author)

Haemopoietic cell renewal in radiation fields

Science.gov (United States)

Fliedner, T. M.; Nothdurft, W.; Tibken, B.; Hofer, E.; Weiss, M.; Kindler, H.

1994-10-01

Space flight activities are inevitably associated with a chronic exposure of astronauts to a complex mixture of ionising radiation. Although no acute radiation consequences are to be expected as a rule, the possibility of Solar Particle Events (SPE) associated with relatively high doses of radiation (1 or more Gray) cannot be excluded. It is the responsibility of physicians in charge of the health of astronauts to evaluate before, during and after space flight activities the functional status of haemopoietic cell renewal. Chronic low level exposure of dogs indicate that daily gamma-exposure doses below about 2 cGy are tolerated for several years as far as blood cell concentrations are concerned. However, the stem cell pool may be severely affected. The maintenance of sufficient blood cell counts is possible only through increased cell production to compensate for the radiation inflicted excess cell loss. This behaviour of haemopoietic cell renewal during chronic low level exposure can be simulated by bioengineering models of granulocytopoiesis. It is possible to define a ``turbulence region'' for cell loss rates, below which an prolonged adaptation to increased radiation fields can be expected to be tolerated. On the basis of these experimental results, it is recommended to develop new biological indicators to monitor haemopoietic cell renewal at the level of the stem cell pool using blood stem cells in addition to the determination of cytokine concentrations in the serum (and other novel approaches). To prepare for unexpected haemopoietic effects during prolonged space missions, research should be increased to modify the radiation sensitivity of haemopoietic stem cells (for instance by the application of certain regulatory molecules). In addition, a ``blood stem cell bank'' might be established for the autologous storage of stem cells and for use in space activities keeping them in a radiation protected container.

Bovine ocular squamous cell carcinoma: UV sensitivity in lymphocytes

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Lavin, M.F.; Jennings, P.A.; Hughes, D.J. (Queensland Univ., Brisbane (Australia))

1982-05-01

Increased sensitivity to UV light has been demonstrated in Phytohaemagglutinin stimulated lymphocytes from normal and tumour-bearing Hereford cattle when compared to lymphocytes from other breeds. Trypan blue exclusion and inhibition of DNA synthesis were used to determine cell viability. The results obtained from time course and radiation dose experiments demonstrate biphasic survival kinetics. This is indicative of at least two separate cell populations, exhibiting differential sensitivity to UV. The increased sensitivity to UV observed in Herefords may reflect a general sensitivity to UV or alternatively a different cellular constitution in the mitogen stimulated cultures. DNA repair synthesis, measured in the presence of hydroxyurea, was of similar levels in cell cultures from Herefords and one of the control breeds.

Radiation sensitizations at DNA-level by chemical and biological agents. Coordinated programme on improvement of radiotherapy of cancer using modifiers of radiosensitivity of cells

International Nuclear Information System (INIS)

Altmann, H.

1982-01-01

Radiation sensitization by chemical agents at DNA level is discussed. Procaine, Halothan and Metronidazole showed no significant effect on unscheduled DNA synthesis (UDS) in mouse spleen cells, investigated by autoradiography and no effect on rejoining of DNA single strand breaks after gamma or UV irradiation. Oxyphenbutazon and prednisolone reduced the replicative DNA synthesis in vitro and in vivo but there was only little effect on DNA repair in the in vivo experiments. These two substances showed also a small reduction in poly(ADP-ribose) synthesis (PAR synthesis). 5-methoxypsoralen (5-MOP) and 8-methoxypsoralen (8-MOP) in combination with UV irradiation showed that 5-MOP was more toxic than mutagen, but induced much less DNA crosslinks than 8-MOP. Autoradiographic studies of radiation sensitization by biological agents showed significant inhibition of UDS in Yoshida tumor cells after acute mycoplasma infection in rats. Nucleoid sedimentation studies showed only in the case of Yoshida tumor cells after mycoplasma infection a dramatic effect in the sedimentation behaviour. Sensitization of cells by changing chromatin structure was also studied. Benzamide, 3-NH 2 -benzamide, 3-Methoxybenzamide, Spermine, Theophyllin and Caffeine were tested in different concentrations on replicative DNA synthesis, UDS after UV irradiation and PAR synthesis Chinese hamster ovary cells. 5-Methoxybenzamide was the strongest sensitizer and inhibitor of the PAR synthesis, and was used in further experiments. Results of KFA Juelich on sensitization of a mamma-adenocarcinoma EO 771 on C57 B1 mice are given. Replicative DNA synthesis, DNA repair and PAR synthesis were compared in spleen cells and adenocarcinoma cells after treatment with 5-Methoxybenzamide. An inhibitory effect on UDS could be shown only in adenocarcinoma cells but not in the mice spleen cells

Dying cells protect survivors from radiation-induced cell death in Drosophila.

Directory of Open Access Journals (Sweden)

Amber Bilak

2014-03-01

Full Text Available We report a phenomenon wherein induction of cell death by a variety of means in wing imaginal discs of Drosophila larvae resulted in the activation of an anti-apoptotic microRNA, bantam. Cells in the vicinity of dying cells also become harder to kill by ionizing radiation (IR-induced apoptosis. Both ban activation and increased protection from IR required receptor tyrosine kinase Tie, which we identified in a genetic screen for modifiers of ban. tie mutants were hypersensitive to radiation, and radiation sensitivity of tie mutants was rescued by increased ban gene dosage. We propose that dying cells activate ban in surviving cells through Tie to make the latter cells harder to kill, thereby preserving tissues and ensuring organism survival. The protective effect we report differs from classical radiation bystander effect in which neighbors of irradiated cells become more prone to death. The protective effect also differs from the previously described effect of dying cells that results in proliferation of nearby cells in Drosophila larval discs. If conserved in mammals, a phenomenon in which dying cells make the rest harder to kill by IR could have implications for treatments that involve the sequential use of cytotoxic agents and radiation therapy.

Cell cycle kinetics and radiation therapy

International Nuclear Information System (INIS)

Mendelsohn, M.L.

1975-01-01

Radiation therapy as currently practiced involves the subtle largely empirical art of balancing the recurrence of cancer due to undertreatment against severe damage to local tissues due to overtreatment. Therapeutic results too often fall short of desired success rates; yet, the therapist is continually tantalized to the likelihood that a slight shift of therapeutic ratio favoring normal tissue over cancer would have a profoundly beneficial effect. The application of cell cycle kinetics to radiation therapy is one hope for improving the therapeutic ratio; but, as I will try to show, kinetic approaches are complex, poorly understood, and presently too elusive to elicit confidence or to be used clinically. Their promise lies in their diversity and in the magnitude of our ignorance about how they work and how they should be used. Potentially useful kinetic approaches to therapy can be grouped into three classes. The first class takes advantage of intracyclic differential sensitivity, an effect involving the metabolism and biology of the cell cycle; its strategies are based on synchronization of cells over intervals of hours to days. The second class involves the distinction between cycling and noncycling cells; its strategies are based on the resistance of noncycling cells to cycle-linked radiation sensitizers and chemotherapeutic agents. The third class uses cell repopulation between fractions; its strategies are based on the relative growth rates of tumor and relevant normal tissue before and after perturbation

Disturbance of DKK1 level is partly involved in survival of lung cancer cells via regulation of ROMO1 and γ-radiation sensitivity

Energy Technology Data Exchange (ETDEWEB)

Kim, In Gyu, E-mail: igkim@kaeri.re.kr [Department of Radiation Biology, Environmental Radiation Research Group, Korea Atomic Energy Research Institute, P.O. Box 105, Yuseong, Daejeon 305-600 (Korea, Republic of); Department of Radiation Biotechnology and Applied Radioisotope, University of Science and Technology (UST), 989-111 Daedeok-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Kim, Seo Yoen [Department of Radiation Biology, Environmental Radiation Research Group, Korea Atomic Energy Research Institute, P.O. Box 105, Yuseong, Daejeon 305-600 (Korea, Republic of); Biomedical Translational Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon 305-806 (Korea, Republic of); Kim, Hyun A; Kim, Jeong Yul [Department of Radiation Biology, Environmental Radiation Research Group, Korea Atomic Energy Research Institute, P.O. Box 105, Yuseong, Daejeon 305-600 (Korea, Republic of); Lee, Jae Ha; Choi, Soo Im [Department of Radiation Biology, Environmental Radiation Research Group, Korea Atomic Energy Research Institute, P.O. Box 105, Yuseong, Daejeon 305-600 (Korea, Republic of); Department of Radiation Biotechnology and Applied Radioisotope, University of Science and Technology (UST), 989-111 Daedeok-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Han, Jeong Ran; Kim, Kug Chan [Department of Radiation Biology, Environmental Radiation Research Group, Korea Atomic Energy Research Institute, P.O. Box 105, Yuseong, Daejeon 305-600 (Korea, Republic of); Cho, Eun Wie [Biomedical Translational Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Yuseong-gu, Daejeon 305-806 (Korea, Republic of)

2014-01-03

Highlights: •DKK1 was expressed differently among non-small-cell lung cancer cell lines. •DKK1 negatively regulated ROMO1 gene expression. •Disturbance of DKK1 level induced the imbalance of cellular ROS. •DKK1/ROMO1-induced ROS imbalance is involved in cell survival in NSCLC. -- Abstract: Dickkopf1 (DKK1), a secreted protein involved in embryonic development, is a potent inhibitor of the Wnt signaling pathway and has been postulated to be a tumor suppressor or tumor promoter depending on the tumor type. In this study, we showed that DKK1 was expressed differently among non-small-cell lung cancer cell lines. The DKK1 expression level was much higher in A549 cells than in H460 cells. We revealed that blockage of DKK1 expression by silencing RNA in A549 cells caused up-regulation of intracellular reactive oxygen species (ROS) modulator (ROMO1) protein, followed by partial cell death, cell growth inhibition, and loss of epithelial–mesenchymal transition property caused by ROS, and it also increased γ-radiation sensitivity. DKK1 overexpression in H460 significantly inhibited cell survival with the decrease of ROMO1 level, which induced the decrease of cellular ROS. Thereafter, exogenous N-acetylcysteine, an antioxidant, or hydrogen peroxide, a pro-oxidant, partially rescued cells from death and growth inhibition. In each cell line, both overexpression and blockage of DKK1 not only elevated p-RB activation, which led to cell growth arrest, but also inactivated AKT/NF-kB, which increased radiation sensitivity and inhibited cell growth. This study is the first to demonstrate that strict modulation of DKK1 expression in different cell types partially maintains cell survival via tight regulation of the ROS-producing ROMO1 and radiation resistance.

Disturbance of DKK1 level is partly involved in survival of lung cancer cells via regulation of ROMO1 and γ-radiation sensitivity

International Nuclear Information System (INIS)

Kim, In Gyu; Kim, Seo Yoen; Kim, Hyun A; Kim, Jeong Yul; Lee, Jae Ha; Choi, Soo Im; Han, Jeong Ran; Kim, Kug Chan; Cho, Eun Wie

2014-01-01

Highlights: •DKK1 was expressed differently among non-small-cell lung cancer cell lines. •DKK1 negatively regulated ROMO1 gene expression. •Disturbance of DKK1 level induced the imbalance of cellular ROS. •DKK1/ROMO1-induced ROS imbalance is involved in cell survival in NSCLC. -- Abstract: Dickkopf1 (DKK1), a secreted protein involved in embryonic development, is a potent inhibitor of the Wnt signaling pathway and has been postulated to be a tumor suppressor or tumor promoter depending on the tumor type. In this study, we showed that DKK1 was expressed differently among non-small-cell lung cancer cell lines. The DKK1 expression level was much higher in A549 cells than in H460 cells. We revealed that blockage of DKK1 expression by silencing RNA in A549 cells caused up-regulation of intracellular reactive oxygen species (ROS) modulator (ROMO1) protein, followed by partial cell death, cell growth inhibition, and loss of epithelial–mesenchymal transition property caused by ROS, and it also increased γ-radiation sensitivity. DKK1 overexpression in H460 significantly inhibited cell survival with the decrease of ROMO1 level, which induced the decrease of cellular ROS. Thereafter, exogenous N-acetylcysteine, an antioxidant, or hydrogen peroxide, a pro-oxidant, partially rescued cells from death and growth inhibition. In each cell line, both overexpression and blockage of DKK1 not only elevated p-RB activation, which led to cell growth arrest, but also inactivated AKT/NF-kB, which increased radiation sensitivity and inhibited cell growth. This study is the first to demonstrate that strict modulation of DKK1 expression in different cell types partially maintains cell survival via tight regulation of the ROS-producing ROMO1 and radiation resistance

Tumor progression: analysis of the instability of the metastatic phenotype, sensitivity to radiation and chemotherapy

International Nuclear Information System (INIS)

Welch, D.R.

1984-01-01

The major complications for tumor therapy are 1) tumor spread (metastasis); 2) the mixed nature of tumors (heterogeneity); and 3) the capacity of tumors to evolve (progress). To study these tumor characteristics, the rat 13762NF mammary adenocarcinoma was cloned and studied for metastatic properties and sensitivities to therapy (chemotherapy, radiation and hyperthermia). The cell clones were heterogeneous and no correlation between metastatic potential and therapeutic sensitivities was observed. Further, these phenotypes were unstable during pasage in vitro; yet, the changes were clone dependent and reproducible using different cryoprotected cell stocks. To understand the phenotypic instability, subclones were isolated from low and high passage cell clones. The results demonstrated that 1) tumor cells are heterogeneous for multiple phenotypes; 2) tumor cells are unstable for multiple phenotypes; 3) the magnitude, direction and time of occurrence of phenotypic drift is clone dependent; 4) the sensitivity of cell clones to ionizing radiation (γ or heat) and chemotherapy agents is independent of their metastatic potential; 5) shifts in metastatic potential and sensitivity to therapy may occur simultaneously but are not linked; and 6) tumor cells independently diverge to form several subpopulations with unique phenotypic profiles

Mesenchymal Stem Cells Retain Their Defining Stem Cell Characteristics After Exposure to Ionizing Radiation

International Nuclear Information System (INIS)

Nicolay, Nils H.; Sommer, Eva; Lopez, Ramon; Wirkner, Ute; Trinh, Thuy; Sisombath, Sonevisay; Debus, Jürgen; Ho, Anthony D.; Saffrich, Rainer; Huber, Peter E.

2013-01-01

Purpose: Mesenchymal stem cells (MSCs) have the ability to migrate to lesion sites and undergo differentiation into functional tissues. Although this function may be important for tissue regeneration after radiation therapy, the influence of ionizing radiation (IR) on cellular survival and the functional aspects of differentiation and stem cell characteristics of MSCs have remained largely unknown. Methods and Materials: Radiation sensitivity of human primary MSCs from healthy volunteers and primary human fibroblast cells was examined, and cellular morphology, cell cycle effects, apoptosis, and differentiation potential after exposure to IR were assessed. Stem cell gene expression patterns after exposure to IR were studied using gene arrays. Results: MSCs were not more radiosensitive than human primary fibroblasts, whereas there were considerable differences regarding radiation sensitivity within individual MSCs. Cellular morphology, cytoskeletal architecture, and cell motility were not markedly altered by IR. Even after high radiation doses up to 10 Gy, MSCs maintained their differentiation potential. Compared to primary fibroblast cells, MSCs did not show an increase in irradiation-induced apoptosis. Gene expression analyses revealed an upregulation of various genes involved in DNA damage response and DNA repair, but expression of established MSC surface markers appeared only marginally influenced by IR. Conclusions: These data suggest that human MSCs are not more radiosensitive than differentiated primary fibroblasts. In addition, upon photon irradiation, MSCs were able to retain their defining stem cell characteristics both on a functional level and regarding stem cell marker expression

Effects of radiation on parafollicular C cells of the thyroid gland

International Nuclear Information System (INIS)

Shah, K.H.; Oslapas, R.; Calandra, D.B.

1983-01-01

While radiation has well-recognized effects on follicular cells of the thyroid gland, those on parafollicular C cells are not yet established. Low-dose radiation that has been proved to be nonablative and carcinogenic to follicular cells was administered to 8-week-old Long-Evans rats to study the changes in C cell number and function. Circulating calcitonin levels were significantly reduced in animals that had undergone radiation at age 24 months. Mean calcitonin values were 0.66 (+/- 0.20) ng/ml and 1.64 (+/- 0.59) ng/ml for control males and females compared with 0.14 (+/- 0.06) ng/ml and 0.11 (+/- 0.01) ng/ml for males (P less than 0.05) and females (P less than 0.001) that had undergone radiation, respectively. These levels correlated well with C cell population density in thyroid glands in the control group and in the group that had undergone radiation as evidenced by light microscopy. Routine hematoxylin and eosin staining showed C cell hyperplasia in 77% of control animals of both sexes compared with 4% in animals that had undergone radiation (P less than 0.005). Immunoperoxidase staining with an anticalcitonin antibody showed virtual absence of C cells in most animals that had undergone radiation compared with diffusely scattered cells in animals in the control group. Medullary carcinomas occurred in 14% of animals in the control group compared with 3% of animals that had undergone radiation (P less than 0.05). These data indicate that the radiation dosage that is carcinogenic to the follicular epithelium causes lethal injury to C cells and thus suggest that C cells are more sensitive to radiation than are follicular cells. This increased sensitivity could explain the virtual absence of C cells, decrease in calcitonin levels, and reduced numbers of medullary carcinomas in the animals that had undergone radiation

Bovine ocular squamous cell carcinoma: UV sensitivity in lymphocytes

International Nuclear Information System (INIS)

Lavin, M.F.; Jennings, P.A.; Hughes, D.J.

1982-01-01

Increased sensitivity to UV light has been demonstrated in Phytohaemagglutinin stimulated lymphocytes from normal and tumour-bearing Hereford cattle when compared to lymphocytes from other breeds. Trypan blue exclusion and inhibition of DNA synthesis were used to determine cell viability. The results obtained from time course and radiation dose experiments demonstrate biphasic survival kinetics. This is indicative of at least two separate cell populations, exhibiting differential sensitivity to UV. The increased sensitivity to UV observed in Herefords may reflect a general sensitivity to UV or alternatively a different cellular constitution in the mitogen stimulated cultures. DNA repair synthesis, measured in the presence of hydroxyurea, was of similar levels in cell cultures from Herefords and one of the control breeds. (author)

Caffeine markedly sensitizes human mesothelioma cell lines to pemetrexed

Science.gov (United States)

Min, Sang Hee; Goldman, I. David; Zhao, Rongbao

2013-01-01

Pemetrexed is a new generation antifolate approved for the treatment of mesothelioma and non-small cell lung cancer. Caffeine is known to augment radiation or chemotherapeutic drug-induced cell killing. The current study addresses the impact of caffeine on the activity of pemetrexed in mesothelioma cell lines. Caffeine enhanced pemetrexed activity in all four mesothelioma cell lines tested (H2052, H2373, H28 and MSTO-211H). Caffeine sensitized H2052 cells in a dose- and schedule-dependent manner, and was associated with a markedly decreased clonogenic survival. Caffeine sensitization occurred only in cells subjected to pulse, but not continuous, exposure to pemetrexed. Similar pemetrexed sensitization was also observed with the clinically better tolerated caffeine analog, theobromine. Pemetrexed sensitization by caffeine was associated with an increase in pemetrexed-induced phosphorylation of ataxia-telangiectasia-mutated (ATM) and Chk1. These data indicate that caffeine and its analog, theobromine, may be a useful approach to enhance pemetrexed-based chemotherapy. PMID:17594092

Effect of free radicals and cultivation media on radiation sensitivities of escherichia coli and related bacteria

International Nuclear Information System (INIS)

Ito, Hitoshi

2000-01-01

Effects of gamma-irradiation on some strains of Escherichia coli, Salmonella enteritidis and Staphylococcus aureus were investigated in the presence of N 2 , N 2 O and O 2 and with the hydroxyl radical (OH) scavengers glycerol, polyethylene glycerol and formate. Injured cell membrane of bacteria was detected using with MacConkey agar for E. coli and S. enteritidis and 7% NaCl Triptic soy agar for St. aureus instead of Tryptic soy agar for recovery medium. From this study, addition of glycerol significantly reduced the sensitivity in all of strains, and cell membrane was not injured significantly except in radiation sensitive strain E. coli A4-1. When superoxide radicals (O 2 ) were generated during irradiation in the presence of formate, injured cell membrane increased significantly in all of strains. However, molecular oxygen (O 2 ) and OH radicals also had some effects on the damage of cell membrane. These results suggest that most radiation induced cell lethality was responsible to the cooperative effects of intracellular OH radicals and O 2 on DNA with lessor effect of damage on cell membrane by O 2 radicals, O 2 and OH radicals. On the radiation sensitive strain of E. coli, cell lethality occurred significantly by the injury of cell membrane compared with other strains. (author)

Comparative studies on the effect of radiation-sensitizing agents used in radiating VX2 Carcinoma

International Nuclear Information System (INIS)

Migita, Hidenobu

1975-01-01

The effects of 5-Fu and BUdR as radiation-sensitizing agents macroscopically were investigated in 122 VX2 Carcinomas transplanted into the calves of the hind legs of rabbits. Experimental groups and contrast groups are divided into six as follows: A: No treatment, B: 5-Fu infusion, C: BUdR+Antimetabolite infusion, D: Radiation, E: 5-Fu infusion and radiation, and F: BUdR+Antimetabolite infusion and radiation. The amount of agent given to each was 5 mg/kg/day of 5-Fu and 50 mg/kg/day of BUdR, and the amount of radiation was 300 rad/day. 5-Fu was used as the Antimetabolite, and its amount was one-tenth of that in the 5-Fu Infusion Group. The agent and the radiation were given for five days. 1. In the 300 rad/day Group, the radiation was not enough to result in a complete cure. 2. In the two Agent Infusion Group, 5-Fu and BUdR+Antimetabolite proved to be anti-cancer, but neither of them resulted in effective treatment. 3. The 5-Fu Infusion and Radiation Group, showed a strong degenerative change in the tumor cell and a radiosensitive effect from 5-Fu, but the tumor was not lessened. 4. In the BUdR-Antimetabolite Infusion and Radiation Group, the tumor began to reduce on the third day. On the seventh and fourteenth days, necrosis of the greater part of tumor was seen, and the rest of the tumor cells were found to be in degenerative change. On the twenty first day, no live tumor cell was found, only dead remains of tumor cells. The results were confirmed both macroscopically and histopathologically. 5. BUdR can be expected to be effective in clinical application to oral malignant tumors. (Evans, J.)

Gimeracil sensitizes cells to radiation via inhibition of homologous recombination

International Nuclear Information System (INIS)

Takagi, Masaru; Sakata, Koh-ichi; Someya, Masanori; Tauchi, Hiroshi; Iijima, Kenta; Matsumoto, Yoshihisa; Torigoe, Toshihiko; Takahashi, Akari; Hareyama, Masato; Fukushima, Masakazu

2010-01-01

Background and purpose: 5-Chloro-2,4-dihydroxypyridine (Gimeracil) is a component of an oral fluoropyrimidine derivative S-1. Gimeracil is originally added to S-1 to yield prolonged 5-FU concentrations in tumor tissues by inhibiting dihydropyrimidine dehydrogenase, which degrades 5-FU. We found that Gimeracil by itself had the radiosensitizing effect. Methods and materials: We used various cell lines deficient in non-homologous end-joining (NHEJ) or homologous recombination (HR) as well as DLD-1 and HeLa in clonogenic assay. γ-H2AX focus formation and SCneo assay was performed to examine the effects of Gimeracil on DNA double strand break (DSB) repair mechanisms. Results: Results of γ-H2AX focus assay indicated that Gimeracil inhibited DNA DSB repair. It did not sensitize cells deficient in HR but sensitized those deficient in NHEJ. In SCneo assay, Gimeracil reduced the frequency of neo-positive clones. Additionally, it sensitized the cells in S-phase more than in G0/G1. Conclusions: Gimeracil inhibits HR. Because HR plays key roles in the repair of DSBH caused by radiotherapy, Gimeracil may enhance the efficacy of radiotherapy through the suppression of HR-mediated DNA repair pathways.

Potentially three distinct roles for hypoxic cell sensitizers in the clinic

International Nuclear Information System (INIS)

Chapman, J.D.; Raleigh, J.A.; Pedersen, J.E.; Ngan, J.; Shum, F.Y.

1979-01-01

Nitroaromatic drugs have been applied to radiation therapy on the basis of their effectiveness to enhance radiation damages selectively in hypoxic mammalian cells at nontoxic concentration. Such sensitizers could improve the rate of local tumor control by conventional radiotherapy in such cases that the resistance due to hypoxia in a limiting factor. The selective cytotoxicity of the drug to hypoxic cells is the second distinct action. A third potential role for nitroaromatic drugs could involve their use for the diagnosis of the number and location of hypoxic cells within tumors. The gain in therapeutic ratio by a factor from 5 to 10 is necessary before the full clinical impact of hypoxic cell radiosensitizers can be evaluated. The drugs selected for the use as clinical radiosensitizers were originally developed as the antibacterial agents with selective activity against anaerobes. The hypoxic cells in tumors are usually resistant to chemotherapy as well as resistant to radiation, and this specific drug action of sensitizers combined with that of an agent effective against oxygenated and cycling cells could possibly produce improved tumor cures. Electron-affinitive chemicals become selectively bound to the macromolecules of hypoxic mammalian cells by radiation-induced chemical reaction. This technique was used to identify by autoradiographic procedures the location of the radioactive nitrofurazone bound to hypoxic cells within multicellular spheroids. (Yamashita, S.)

Attenuation of the DNA Damage Response by Transforming Growth Factor-Beta Inhibitors Enhances Radiation Sensitivity of Non–Small-Cell Lung Cancer Cells In Vitro and In Vivo

Energy Technology Data Exchange (ETDEWEB)

Du, Shisuo; Bouquet, Sophie; Lo, Chen-Hao; Pellicciotta, Ilenia; Bolourchi, Shiva [Department of Radiation Oncology, New York University School of Medicine, New York, New York (United States); Parry, Renate [Varian Medical Systems, Palo Alto, California (United States); Barcellos-Hoff, Mary Helen, E-mail: mhbarcellos-hoff@nyumc.org [Department of Radiation Oncology, New York University School of Medicine, New York, New York (United States)

2015-01-01

Purpose: To determine whether transforming growth factor (TGF)-β inhibition increases the response to radiation therapy in human and mouse non–small-cell lung carcinoma (NSCLC) cells in vitro and in vivo. Methods and Materials: TGF-β–mediated growth response and pathway activation were examined in human NSCLC NCI-H1299, NCI-H292, and A549 cell lines and murine Lewis lung cancer (LLC) cells. Cells were treated in vitro with LY364947, a small-molecule inhibitor of the TGF-β type 1 receptor kinase, or with the pan-isoform TGF-β neutralizing monoclonal antibody 1D11 before radiation exposure. The DNA damage response was assessed by ataxia telangiectasia mutated (ATM) or Trp53 protein phosphorylation, γH2AX foci formation, or comet assay in irradiated cells. Radiation sensitivity was determined by clonogenic assay. Mice bearing syngeneic subcutaneous LLC tumors were treated with 5 fractions of 6 Gy and/or neutralizing or control antibody. Results: The NCI-H1299, A549, and LLC NSCLC cell lines pretreated with LY364947 before radiation exposure exhibited compromised DNA damage response, indicated by decreased ATM and p53 phosphorylation, reduced γH2AX foci, and increased radiosensitivity. The NCI-H292 cells were unresponsive. Transforming growth factor-β signaling inhibition in irradiated LLC cells resulted in unresolved DNA damage. Subcutaneous LLC tumors in mice treated with TGF-β neutralizing antibody exhibited fewer γH2AX foci after irradiation and significantly greater tumor growth delay in combination with fractionated radiation. Conclusions: Inhibition of TGF-β before radiation attenuated DNA damage recognition and increased radiosensitivity in most NSCLC cells in vitro and promoted radiation-induced tumor control in vivo. These data support the rationale for concurrent TGF-β inhibition and RT to provide therapeutic benefit in NSCLC.

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)

Specific inhibition of Wee1 kinase and Rad51 recombinase: A strategy to enhance the sensitivity of leukemic T-cells to ionizing radiation-induced DNA double-strand breaks

International Nuclear Information System (INIS)

Havelek, Radim; Cmielova, Jana; Kralovec, Karel; Bruckova, Lenka; Bilkova, Zuzana; Fousova, Ivana; Sinkorova, Zuzana; Vavrova, Jirina; Rezacova, Martina

2014-01-01

Highlights: • Pre-treatment with the inhibitors increased the sensitivity of Jurkat cells to irradiation. • Combining both inhibitors together resulted in a G2 cell cycle arrest abrogation in Jurkat. • Jurkat cells pre-treated with inhibitors were positive for γH2AX foci 24 h upon irradiation. • Pre-treatment with Rad51 RI-1 had no effect on apoptosis induction in MOLT-4 cells. • When dosed together, the combination decreased MOLT-4 cell survival. - Abstract: Present-day oncology sees at least two-thirds of cancer patients receiving radiation therapy as a part of their anticancer treatment. The objectives of the current study were to investigate the effects of the small molecule inhibitors of Wee1 kinase II (681641) and Rad51 (RI-1) on cell cycle progression, DNA double-strand breaks repair and apoptosis following ionizing radiation exposure in human leukemic T-cells Jurkat and MOLT-4. Pre-treatment with the Wee1 681641 or Rad51 RI-1 inhibitor alone increased the sensitivity of Jurkat cells to irradiation, however combining both inhibitors together resulted in a further enhancement of apoptosis. Jurkat cells pre-treated with inhibitors were positive for γH2AX foci 24 h upon irradiation. MOLT-4 cells were less affected by inhibitors application prior to ionizing radiation exposure. Pre-treatment with Rad51 RI-1 had no effect on apoptosis induction; however Wee1 681641 increased ionizing radiation-induced cell death in MOLT-4 cells

Studies on the Mechanism of Radiation Resistance in Micrococcus Radiodurans and its Sensitization

Energy Technology Data Exchange (ETDEWEB)

Kitayama, S.; Matsuyama, A. [Radiobiology Laboratory, Institute of Physical and Chemical Research, Wako-shi, Saitama-ken (Japan)

1978-06-15

Efficient and accurate repair of radiation-induced lesions in M. radiodurans was investigated as to the cause of its extreme radioresistance. The cells were made permeable to deoxyribonucleoside triphosphate by treatment with non-ionic detergent, Triton X-100. After irradiation with 2 krad gamma rays more than 80% of the single-strand scissions were rejoined in the permeable cells within 10 min at 37 Degree-Sign C. This fast repair process requires the presence of deoxyribonucleoside triphosphates and NAD. However, rejoining of DNA strand scission was incomplete after prolonged incubation in the permeable cells. This suggests that alternate repair reaction(s) is necessary for complete recovery. The other type of radiation lesion was found by postirradiation incubation at non-permissive temperature, which markedly sensitizes this bacterium to radiation. Postincubation at this temperature also sensitizes the cells to chemicals that damage DNA. The extreme radioresistance of this bacterium was also lost by mutation and an isolated radiosensitive mutant showed almost the same radiosensitivity as E. coli K12 or B/r. These results are discussed in connection with the extreme radioresistance of M. radiodurans. (author)

Studies on the mechanism of radiation resistance in Micrococcus radiodurans and its sensitization

International Nuclear Information System (INIS)

Kitayama, S.; Matsuyama, A.

1978-01-01

Efficient and accurate repair of radiation-induced lesions in M. radiodurans was investigated as to the cause of its extreme radioresistance. The cells were made permeable to deoxyribonucleoside triphosphate by treatment with non-ionic detergent, Triton X-100. After irradiation with 2 krad gamma rays more than 80% of the single-strand scissions were rejoined in the permeable cells within 10 min at 37 0 C. This fast repair process requires the presence of deoxyribonucleoside triphosphates and NAD. However, rejoining of DNA strand scission was incomplete after prolonged incubation in the permeable cells. This suggests that alternate repair reaction(s) is necessary for complete recovery. The other type of radiation lesion was found by post-irradiation incubation at non-permissive temperature, which markedly sensitizes this bacterium to radiation. Postincubation at this temperature also sensitizes the cells to chemicals that damage DNA. The extreme radioresistance of this bacterium was also lost by mutation and an isolated radiosensitive mutant showed almost the same radiosensitivity as E. coli K12 or B/r. These results are discussed in connection with the extreme radioresistance of M. radiodurans. (author)

Antiangiogenic Agent Might Upgrade tumor Cell Sensitivity to Ionizing Radiation

International Nuclear Information System (INIS)

Badr, N.M.S.A.

2013-01-01

The understanding of the fundamental role of angiogenesis and metastasis in cancer growth has led to tremendous interest in research regarding its regulatory mechanisms and clinical implications in the management of cancer. The present study was conducted to evaluate the influence of the angiogenic regulators modification on the tumor growth and the cell sensitivity to ionizing radiation targeting the improvement of cancer therapeutic protocols. Accordingly, the antiangiogenic activity of apigenin and selenium was tested in vitro via MTT assay. The action of Apigenin and or Selenium was examined in vivo by using a model of solid tumor carcinoma (EAC). The growth rate of solid tumor in all experimental groups was measured by Caliper. The irradiated mice were exposed to 6.5 Gy of gamma rays. Apigenin 50 mg/kg body weight and selenium 5 μg per mice were daily administrated for 14 consecutive days after tumor volume reached 1mm 3 . The angiogenic activators TNF-α (key cytokine) in spleen, serum MMP 2 and MMP 9, liver and tumor NO, the lipid peroxidation (LPx) and angiogenic inhibitor TIMP-1 in spleen as well as, antioxidant markers (CAT, SOD, GPX) in tumor and liver tissue and DNA fragmentation in splenocytes were estimated to monitor efficacy of Apigenin and selenium in cancer treatment strategy. All parameters were determined as a time course on days 16 and 22 after tumor volume reached 1mm 3 . The using of MTT assay on EAC cells shows inhibition in EAC cell proliferation after the incubation with apigenin and /or selenium. The administration of apigenin and /or selenium to mice bearing tumor and to irradiated mice bearing tumor reduce significantly the TNF-α expression, MMP 2,9 , NO , LPx level and increased the antioxidant enzymes (GPx , SOD and CAT) activities. The DNA fragmentation and the antiangiogenic factors TIMP-1 were significantly increased when compared with their values in mice bearing tumor or in irradiated mice bearing tumor. From the results

Near-ultraviolet radiation-induced damage using an actinic reticuloid strain as a possible sensitive model

International Nuclear Information System (INIS)

Kralli, A.

1987-01-01

The introduction to this thesis consists of a review of current concepts regarding the effects of ultraviolet radiation on living cells. Actinic reticuloid, a disease condition for which a near-ultraviolet radiation cellular sensitivity has been proposed as an underlying cause, is described. The experimental work, the broad aim of which is to expand existing knowledge of the effects of near-ultraviolet radiation that may lead to cell lethality, has centred upon the irradiation of a normal human skin fibroblast strain, GM730, and a strain derived from an actinic reticuloid patient, AR6LO. Parts 1 and 2 examine the effects of the irradiation on both normal and actinic fibroblast sensitivities to a range of ultraviolet wavelengths. The next two sections include observations on the protective effect of Trolox-C, a vitamin E analogue and the sensitization resulting from the replacement of the irradiation medium by a deuterated one, using both normal and actinic reticuloid fibroblasts. The final part examines broad-band near- and far-ultraviolet radiation induced membrane damage by the use of radioactively labelled rubidium as a potassium analogue. (author)

Oocyte toxicity: female germ-cell loss from radiation and chemical exposures

International Nuclear Information System (INIS)

Dobson, R.L.

1984-01-01

In some mammals, female germ cells are extraordinarily sensitive to killing by exposure to ionizing radiation, especially during development. Immature oocytes, which constitute the lifetime germ-cell pool of the female, have an LD 50 in juvenile mice of only 6 rad (compared with typical LD 50 s of 100-300 rad for most other cell types studied). Essentially, the entire germ-cell supply in female squirrel monkeys is destroyed prenatally by exposure of only 0.7 rad/day. Severe but lesser destruction has been found in other species. However, evidence suggests (though not ruled out for all developmental stages) that unusually high sensitivity probably does not occur in the human female. Germ cells can also be killed by certain chemicals, and similarities exist between chemical and radiation effects. More than 75 compounds have been quantitatively studied in mice, with determination of OTI values (OTI = oocyte toxicity index = mouse LD 50 /oocyte LD 50 ) to measure the degree of preferential oocyte killing. High sensitivity in mice does not mean necessarily high sensitivity in women. Of special interest is the recent discovery that the lethal target in the extremely sensitive mouse immature oocyte is probably the plasma membrane, not DNA. Since mouse data form the main basis from which human genetic hazard (for both radiation and chemicals) is estimated, this has important implications for the determination of genetic risk in women

TAS-116, a novel Hsp90 inhibitor, selectively enhances radio-sensitivity of human cancer cells to X-rays and carbon ion radiation

Science.gov (United States)

Lee, Younghyun; Sunada, Shigeaki; Hirakawa, Hirokazu; Fujimori, Akira; Nickoloff, Jac A.; Okayasu, Ryuichi

2016-01-01

Hsp90 inhibitors have been investigated as cancer therapeutics in mono-therapy and to augment radiotherapy, however serious adverse effects of early generation Hsp90 inhibitors limited their development. TAS-116 is a novel Hsp90 inhibitor with lower adverse effects than other Hsp90 inhibitors, and here we investigated the radio-sensitizing effects of TAS-116 in low LET X-ray, and high LET carbon ion irradiated human cancer cells and mouse tumor xenografts. TAS-116 decreased cell survival of both X-ray and carbon ion-irradiated human cancer cell lines (HeLa and H1299 cells), and similar to other Hsp90 inhibitors, it did not affect radiosensitivity of non-cancerous human fibroblasts. TAS-116 increased the number of radiation-induced γ-H2AX foci, and delayed the repair of DNA double-strand breaks (DSBs). TAS-116 reduced the expression of proteins that mediate repair of DSBs by homologous recombination (RAD51) and non-homologous end joining (Ku, DNA-PKcs), and suppressed formation of RAD51 foci and phosphorylation/activation of DNA-PKcs. TAS-116 also decreased expression of the cdc25 cell cycle progression marker, markedly increasing G2/M arrest. Combined treatment of mouse tumor xenografts with carbon ions and TAS-116 showed promising delay in tumor growth compared to either individual treatment. These results demonstrate that TAS-116 radio-sensitizes human cancer cells to both X rays and carbon ions by inhibiting the two major DSB repair pathways, and these effects were accompanied by marked cell cycle arrest. The promising results of combination TAS-116 + carbon ion radiation therapy of tumor xenografts justify further exploration of TAS-116 as an adjunct to radiotherapy using low or high LET radiation. PMID:28062703

Correlation between endogenous glutathione content and sensitivity of cultured human skin cells to radiation at defined wavelengths in the solar ultraviolet range

International Nuclear Information System (INIS)

Tyrrell, R.M.; Pidoux, M.

1988-01-01

Glutathione depletion of cultured human skin fibroblasts by treatment with buthionine-S.R.-sulfoximine (BSO) sensitises them to solar UV radiation. We now show that there is a close quantitative correlation between cellular glutathione content and sensitivity to radiation at 365 nm. A weaker correlation is observed when cells are depleted of glutathione using diethylmaleimide. Both fibroblasts and epidermal keratinocytes derived from the same foreskin biopsy are sensitised to radiation at 313 nm by glutathione depletion. At low to intermediate fluence levels, 10 mM cysteamine present during irradiation at 302 nm is able to almost completely reverse the sensitising effects of glutathione depletion suggesting that the endogenous thiol protects against radiation at this wavelength by a free radical scavenging mechanism. At 313 nm, the sensitisation is not reversed by cysteamine suggesting that glutathione plays a more specific role in protection against radiation at longer wavelengths. Xeroderma pigmentosum group A fibroblasts (excision deficient) are also sensitised to radiation at 313 and 365 nm by depletion of glutathione. The results provide further evidence that endogenous glutathione is involved in protecting human skin cells against a wide range of solar radiation damage. (author)

A ΔdinB mutation that sensitizes Escherichia coli to the lethal effects of UV- and X-radiation

Energy Technology Data Exchange (ETDEWEB)

Lee, Mei-Chong W.; Franco, Magdalena; Vargas, Doris M. [Department of Biological Sciences, San Jose State University, San Jose, CA 95192 (United States); Hudman, Deborah A. [Department of Microbiology and Immunology, A.T. Still University, Kirksville College of Osteopathic Medicine, Kirksville, MO 63501 (United States); White, Steven J. [Department of Biological Sciences, San Jose State University, San Jose, CA 95192 (United States); Fowler, Robert G., E-mail: rfowler@sjsu.edu [Department of Biological Sciences, San Jose State University, San Jose, CA 95192 (United States); Sargentini, Neil J. [Department of Microbiology and Immunology, A.T. Still University, Kirksville College of Osteopathic Medicine, Kirksville, MO 63501 (United States)

2014-05-15

Highlights: • We describe Δ(dinB-yafN)883(::kan), a novel dinB allele, referred to as ΔdinB883, a deletion that sensitizes E. coli cells to UV irradiation. • This UV radiation sensitivity is most acute in the early logarithmic phase of culture growth. • This UV radiation sensitivity is completely dependent upon a functional umuDC operon. • Sequencing reveals ΔdinB883 retains the proximal 161 nucleotides, i.e., 54 amino acids, of the wild-type sequence. • The ΔdinB883 mutant is hypothesized to produce a peptide of 83 amino acids, DinB883, that compromises UmuDC function. - Abstract: The DinB (PolIV) protein of Escherichia coli participates in several cellular functions. We investigated a dinB mutation, Δ(dinB-yafN)883(::kan) [referred to as ΔdinB883], which strongly sensitized E. coli cells to both UV- and X-radiation killing. Earlier reports indicated dinB mutations had no obvious effect on UV radiation sensitivity which we confirmed by showing that normal UV radiation sensitivity is conferred by the ΔdinB749 allele. Compared to a wild-type strain, the ΔdinB883 mutant was most sensitive (160-fold) in early to mid-logarithmic growth phase and much less sensitive (twofold) in late log or stationary phases, thus showing a growth phase-dependence for UV radiation sensitivity. This sensitizing effect of ΔdinB883 is assumed to be completely dependent upon the presence of UmuDC protein; since the ΔdinB883 mutation did not sensitize the ΔumuDC strain to UV radiation killing throughout log phase and early stationary phase growth. The DNA damage checkpoint activity of UmuDC was clearly affected by ΔdinB883 as shown by testing a umuC104 ΔdinB883 double-mutant. The sensitivities of the ΔumuDC strain and the ΔdinB883 ΔumuDC double-mutant strain were significantly greater than for the ΔdinB883 strain, suggesting that the ΔdinB883 allele only partially suppresses UmuDC activity. The ΔdinB883 mutation partially sensitized (fivefold) uvrA and uvr

MiR-33a Decreases High-Density Lipoprotein-Induced Radiation Sensitivity in Breast Cancer

Energy Technology Data Exchange (ETDEWEB)

Wolfe, Adam R.; Bambhroliya, Arvind [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Morgan Welch Inflammatory Breast Cancer Research Program and Clinic, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Reddy, Jay P. [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Debeb, Bisrat G. [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Morgan Welch Inflammatory Breast Cancer Research Program and Clinic, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Huo, Lei [Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Larson, Richard; Li, Li [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Morgan Welch Inflammatory Breast Cancer Research Program and Clinic, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Ueno, Naoto T. [Morgan Welch Inflammatory Breast Cancer Research Program and Clinic, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Woodward, Wendy A., E-mail: wwoodward@mdanderson.org [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Morgan Welch Inflammatory Breast Cancer Research Program and Clinic, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)

2016-06-01

Purpose: We previously showed that high-density lipoprotein (HDL) radiosensitizes inflammatory breast cancer (IBC) cells in vitro and is associated with better local control after radiation therapy in IBC patients. The microRNA miR-33 family negatively regulates the adenosine triphosphate binding cassette transporter subfamily A member 1. We hypothesized that variations in miR-33a expression in IBC cancer cells versus non-IBC cells would correlate with radiation sensitivity following exposure to HDL in vitro. Methods and Materials: MiR-33a expression was analyzed by reverse transcriptase–polymerase chain reaction in 4 cell lines representing common clinical breast cancer subtypes. Overexpression and knockdown of miR-33a was demonstrated via transfection of an miR-33a mimic or an anti-miR-33a construct in high- and low-expressing miR-33a cell lines. Clonogenic survival in vitro in these cells was quantified at baseline and following HDL treatment. MiR-33a expression on distant relapse-free survival (DRFS) of 210 cases downloaded from the Oxford breast cancer dataset was determined. Results: Expression levels of miR-33a were lower in IBC cell lines and IBC tumor samples than in non-IBC cell lines and normal breast tissue. Cholesterol concentrations in the cell membranes were higher in IBC cells than in non-IBC cells. Clonogenic survival following 24 hours of HDL treatment was decreased in response to irradiation in the low-miR-33a–expressing cell lines SUM149 and KPL4, but survival following HDL treatment decreased in the high-miR-33a–expressing cell lines MDA-MB-231 and SUM159. In the high-miR-33a–expressing cell lines, anti-miR-33a transfection decreased radiation resistance in clonogenic assays. Conversely, in the low-miR-33a–expressing cell lines, the miR-33a mimic reversed the HDL-induced radiation sensitization. Breast cancer patients in the top quartile based on miR-33a expression had markedly lower rates of DRFS than the bottom quartile (P

MiR-33a Decreases High-Density Lipoprotein-Induced Radiation Sensitivity in Breast Cancer

International Nuclear Information System (INIS)

Wolfe, Adam R.; Bambhroliya, Arvind; Reddy, Jay P.; Debeb, Bisrat G.; Huo, Lei; Larson, Richard; Li, Li; Ueno, Naoto T.; Woodward, Wendy A.

2016-01-01

Purpose: We previously showed that high-density lipoprotein (HDL) radiosensitizes inflammatory breast cancer (IBC) cells in vitro and is associated with better local control after radiation therapy in IBC patients. The microRNA miR-33 family negatively regulates the adenosine triphosphate binding cassette transporter subfamily A member 1. We hypothesized that variations in miR-33a expression in IBC cancer cells versus non-IBC cells would correlate with radiation sensitivity following exposure to HDL in vitro. Methods and Materials: MiR-33a expression was analyzed by reverse transcriptase–polymerase chain reaction in 4 cell lines representing common clinical breast cancer subtypes. Overexpression and knockdown of miR-33a was demonstrated via transfection of an miR-33a mimic or an anti-miR-33a construct in high- and low-expressing miR-33a cell lines. Clonogenic survival in vitro in these cells was quantified at baseline and following HDL treatment. MiR-33a expression on distant relapse-free survival (DRFS) of 210 cases downloaded from the Oxford breast cancer dataset was determined. Results: Expression levels of miR-33a were lower in IBC cell lines and IBC tumor samples than in non-IBC cell lines and normal breast tissue. Cholesterol concentrations in the cell membranes were higher in IBC cells than in non-IBC cells. Clonogenic survival following 24 hours of HDL treatment was decreased in response to irradiation in the low-miR-33a–expressing cell lines SUM149 and KPL4, but survival following HDL treatment decreased in the high-miR-33a–expressing cell lines MDA-MB-231 and SUM159. In the high-miR-33a–expressing cell lines, anti-miR-33a transfection decreased radiation resistance in clonogenic assays. Conversely, in the low-miR-33a–expressing cell lines, the miR-33a mimic reversed the HDL-induced radiation sensitization. Breast cancer patients in the top quartile based on miR-33a expression had markedly lower rates of DRFS than the bottom quartile (P

Radio-sensitization by Piper longumine of human breast adenoma MDA-MB-231 cells in vitro.

Science.gov (United States)

Yao, Jian-Xin; Yao, Zhi-Feng; Li, Zhan-Feng; Liu, Yong-Biao

2014-01-01

The current study investigated the effects of Piper longumine on radio-sensitization of human breast cancer MDA-MB-231 cells and underlying mechanisms. Human breast cancer MDA-MB-231 cells were cultured in vitro and those in logarithmic growth phase were selected for experiments divided into four groups: control, X-ray exposed, Piper longumine, and Piper longumine combined with X-rays. Conogenic assays were performed to determine the radio-sensitizing effects. Cell survival curves were fitted by single-hit multi-target model and then the survival fraction (SF), average lethal dose (D0), quasi-threshold dose (Dq) and sensitive enhancement ratio (SER) were calculated. Cell apoptosis was analyzed by flow cytometry (FCM).Western blot assays were employed for expression of apoptosis-related proteins (Bc1-2 and Bax) after treatment with Piper longumine and/or X-ray radiation. The intracellular reactive oxygen species (ROS) level was detected by FCM with a DCFH-DA probe. The cloning formation capacity was decreased in the group of piperlongumine plus radiation, which displayed the values of SF2, D0, Dq significantly lower than those of radiation alone group and the sensitive enhancement ratio (SER) of D0 was1.22 and 1.29, respectively. The cell apoptosis rate was increased by the combination treatment of Piper longumine and radiation. Piper longumine increased the radiation-induced intracellular levels of ROS. Compared with the control group and individual group, the combination group demonstrated significantly decreased expression of Bcl-2 with increased Bax. Piper longumine at a non-cytotoxic concentration can enhance the radio-sensitivity of MDA- MB-231cells, which may be related to its regulation of apoptosis-related protein expression and the increase of intracellular ROS level, thus increasing radiation-induced apoptosis.

Radiation sensitive solid state devices

International Nuclear Information System (INIS)

Shannon, J.M.; Ralph, J.E.

1975-01-01

A solid state radiation sensitive device is described employing JFETs as the sensitive elements. Two terminal construction is achieved by using a common conductor to capacitively couple to the JFET gate and to one of the source and drain connections. (auth)

Ethacrynic acid: a novel radiation enhancer in human carcinoma cells

International Nuclear Information System (INIS)

Khil, Mark S.; Sang, Hie Kim; Pinto, John T.; Jae, Ho Kim

1996-01-01

Purpose: Because agents that interfere with thiol metabolism and glutathione S-transferase (GST) functions have been shown to enhance antitumor effects of alkylating agents in vitro and in vivo, the present study was conceived on the basis that an inhibitor of GST would enhance the radiation response of some selected human carcinoma cells. Ethacrynic acid (EA) was chosen for the study because it is an effective inhibitor of GST and is a well known diuretic in humans. Methods and Materials: Experiments were carried out with well-established human tumor cells in culture growing in Eagle's minimum essential medium (MEM) supplemented with 10% fetal calf serum (FCS). Cell lines used were MCF-7, MCF-7 adriamycin resistant (AR) cells (breast carcinoma), HT-29 cells (colon carcinoma), DU-145 cells (prostate carcinoma), and U-373 cells (malignant glioma). Cell survival following the exposure of cells to drug alone, radiation alone, and a combined treatment was assayed by determining the colony-forming ability of single plated cells in culture to obtain dose-survival curves. The drug enhancement ratio was correlated with levels of GST. Results: The cytotoxicity of EA was most pronounced in MCF-7, U-373, and DU-145 cells compared to MCF-7 AR and HT-29 cells. The levels of GST activity were found to be lower in those EA-sensitive cells. A significant radiation enhancement was obtained with EA-sensitive cells exposed to nontoxic concentrations of the drug immediately before or after irradiation. The sensitizer enhancement ratio (SER) of MCF-7 cells was 1.55 with EA (20 μg/ml), while the SER of MCF-7 AR was less than 1.1. Based on five different human tumor cells, a clear inverse relationship was demonstrated between the magnitude of SER and GST levels of tumor cells prior to the combined treatment. Conclusion: The present results suggest that EA, which acts as both a reversible and irreversible inhibitor of GST activity, could significantly enhance the radiation response of

Sensitivity of Escherichia coli acrA Mutants to Psoralen plus Near-Ultraviolet Radiation

DEFF Research Database (Denmark)

Hansen, M. Trier

1982-01-01

The sensitivity to psoralen plus near-ultraviolet radiation (PUVA) was compared in a pair of E. coli strains differing at the acrA locus. Survival was determined for both bacteria and phage λ. AcrA mutant cells were 40 times more sensitive than wild type to the lethal effect of PUVA. Free λ phage...

Radiation induced bystander effects in modification of cellular radio-sensitivity in human cancer cells

International Nuclear Information System (INIS)

Pandey, B.N.

2012-01-01

Radiation-induced Bystander Effect is manifestation of radiation effects in non-irradiated cells in the population. The phenomenon may have significant implication in risk of radiation induced cancer incidence and outcome of cancer radiotherapy. To understand the bystander interaction in tumor cells, we have studied secretion of diffusible factors from control and irradiated tumor cells of different origin. Our results showed a good correlation between magnitude of secretion of diffusible factors and survival of tumor cells. These diffusible factors are shown to affect proliferation and survival of tumor cells involving regulation of kinases and genes/proteins involved in apoptotic machinery. Our experiments using pharmacological inhibitors showed involvement of activating transcription factor 2 (ATF-2) signaling in survival of tumor cells after treatment with diffusible factors. These factors seem to be involved in exerting radio-resistance in tumor cells. Furthermore, in proton microbeam irradiation studies showed induction of double strand break measured as gH2AX foci in human lung carcinoma cells, which was found to propagate to bystander tumor cells during post-irradiation incubation. Implication of these observations in outcome of cancer radiotherapy scenario would be discussed. (author)

Modification of the radiation sensitivity of human tumour cells by a bis-benzimidazole derivative

Energy Technology Data Exchange (ETDEWEB)

Smith, P J; Anderson, C O [Medical Research Council, Cambridge (UK)

1984-10-01

A comparison was made of the ability of either X-radiation or a DNA-specific ligand (the vital bis-benzimidazole dye; Hoechst 33342) to induce: cell killing, inhibition of de novo DNA synthesis, DNA strand breakage and the delay of cell division in human colon adenocarcinoma cells in vitro. Unlike radiation-induced cell killing, ligand-induced cytotoxicity appeared to be positively correlated with the extent of inhibition of de novo DNA synthesis-a feature consistent with the persistent binding of ligand molecules to nuclear DNA. Ligand-induced DNA strand-breaks disappeared slowly although ligand-treated cells retained apparently normal capacities to repair discrete radiogenic DNA strand-breaks. Pre-treatment of cells with Hoechst 33342 resulted in a dose-modifying enhancement of radiation resistance not associated with altered dosimetry for strand-break induction. However, radioresistance was accompanied by the protracted retention of cells in the G/sub 2/ phase of the cell cycle. We suggest that the results provide direct evidence that the retention of cells in G/sub 2/ phase is a sparing phenomenon and is triggered by the responses of chromatin domains to the presence of DNA damage.

Control of radiation sensitivity of mammalian cells. Regulation of expression of DNA repair genes

International Nuclear Information System (INIS)

Yoshida, Kayo; Morita, Takashi

2003-01-01

This review describes authors' investigations concerning regulation of expression of DNA repair genes for the purpose of control of radiosensitivity of mammalian cells for cancer radiotherapy. One of their experiments concerns the enhancement of sensitivity to radiation and anti-tumor agents by suppressing the expression of mammalian Rad51 gene which playing a central role in recombination repair against DNA double-strand break, by RNA interference (RNAi). Described are the mode of action of RNAi, mechanism of suppression of Rad51 gene expression by it, enhancing effect in radiosensitivity, stable suppression and enhancement by hairpin RNA and its possible usefulness in cancer therapy. The other concerns the histone H2AX gene, which delivering the repair signal post phosphorylation in chromatin against the double-strand break. Experimental results of suppression of the histone H2AX gene by tet-off system, enhancement of radiosensitivity by the suppression and functional recovery by the gene transfer are described, and the radiosensitivity can be thus artificially controlled by tetracycline in authors' F9 2AX (tet/tet) cells. (N.I.)

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)

Photodamage of the cells in culture sensitized with bilirubin

Science.gov (United States)

Kozlenkova, O. A.; Plavskaya, L. G.; Mikulich, A. V.; Leusenko, I. A.; Tretyakova, A. I.; Plavskii, V. Yu

2016-08-01

It has been shown that exposure to radiation of LED sources of light with an emission band maximum at about 465 and 520 nm having substantially identical damaging effects on animal cells in culture, that are in a logarithmic growth phase and preincubated with pigment. Photobiological effect is caused by photodynamic processes involving singlet oxygen generated by triplet excited sensitizer. Mono-exponential type dependence of cell survival on the energy dose indicates that it is bilirubin that acts as a sensitizer but not its photoproducts. The inclusion of bilirubin in the cells, where it is primarily localized in the mitochondria cells, it is accompanied by multiple amplification photochemical stability compared to pigment molecules bound with albumin

Radiation-sensitive diacrylates

International Nuclear Information System (INIS)

Demajistre, R.

1976-01-01

Novel diacrylates are prepared by reacting a monohydroxylated acrylic monomer with a polyisocyanate. The reaction product may be polymerized by subjecting to ionizing irradiation, actinic light or to free radical catalysts to form a useful coating material. The diacrylates may also be copolymerized with other radiation sensitive materials. 6 claims, no drawings

Hypoxic-cell sensitizers

International Nuclear Information System (INIS)

Dische, S.

1983-01-01

There is now 6 years of clinical experience with misonidazole as a hypoxic-cell sensitizer. Neurotoxicity limits the total dose which may be given, and so relatively low concentrations of radiosensitizing drugs are likely to be achieved in hypoxic cells in man as compared with those in animal tumors. It is likely that benefit will only be shown in those situations where radioresistant hypoxic cells strongly dominate as a cause of radiation failure. Many clinical trials are underway, and thus far some show no benefit while in others there is a definite advantage to the patients given the drug. These trials must be continued to their conclusion, but misonidazole must be regarded as the first of a series of radiosensitizers to reach the clinic for trial. There is a promise of more effective drugs becoming available within the next few years. Those showing a lower lipophilicity than misonidazole have been found to have a shorter half-life and a lower uptake in neural tissue in animal studies. One such drug, desmethylmisonidazole, is presently undergoing clinical trial

Bio-molecular alterations induced by a chemical or radiating stress in isolated human cells

International Nuclear Information System (INIS)

Gault, N.

2004-01-01

After having recalled some aspects of radiobiology (effects of ionizing radiations, molecular targets of radiations, cellular responses with respect to the radiation), the author discusses various aspects of radio-sensitivity: intrinsic radio-sensitivity of tumoral and normal cells, DNA injuries and in vitro radio-sensitivity, genes of susceptibility to ionizing radiations, clustered injuries. Then she reports investigations performed by infrared micro-spectroscopy: characterization of pathological lines, of biological processes, of oxidative injuries induced by xenobiotics, of injuries induced by ionizing radiations

Mutation induction in a mouse lymphoma cell mutant sensitive to 4-nitroquinoline 1-oxide and ultraviolet radiation

International Nuclear Information System (INIS)

Sato, K.; Hieda, N.

1980-01-01

The mutant mouse lymphoma cell Q31, which is sensitive to 4-nitroquinoline 1-oxide and ultraviolet radiation (UV), was compared with the parental L5178Y cell for the effect of caffeine and mutation induction after UV irradiation. Caffeine potentiated the lethal effect of UV in both cell strains to a similar extent, indicating that the defective process in Q31 cells was caffeine-insensitive. UV-induced mutation to 6-thioguanine resistance was determined in L5178Y and Q31 cells. The maximal yield of mutants was obtained 7 days post-irradiation in L5178Y cells and 14 days in Q31 cells for higher UV doses. It appears that a much longer time is required for the mutant cells than for the parental cells for full expression of the resistance phenotype even at equitoxic UV doses. A substantially higher frequency in induced mutations was observed in Q31 cells than in L5178Y cells at a given dose of UV. A plot of induced mutation frequency as a function of logarithm of surviving fraction again indicates hypermutability of Q31 cells as compared with the parental strain. In contrast, X-rays induced a similar frequency of mutations to 6-thioguanine resistance in L5178Y and Q31 cells. (orig.)

Ionizing Radiation Induces Morphological Changes and Immunological Modulation of Jurkat Cells.

Science.gov (United States)

Voos, Patrick; Fuck, Sebastian; Weipert, Fabian; Babel, Laura; Tandl, Dominique; Meckel, Tobias; Hehlgans, Stephanie; Fournier, Claudia; Moroni, Anna; Rödel, Franz; Thiel, Gerhard

2018-01-01

Impairment or stimulation of the immune system by ionizing radiation (IR) impacts on immune surveillance of tumor cells and non-malignant cells and can either foster therapy response or side effects/toxicities of radiation therapy. For a better understanding of the mechanisms by which IR modulates T-cell activation and alters functional properties of these immune cells, we exposed human immortalized Jurkat cells and peripheral blood lymphocytes (PBL) to X-ray doses between 0.1 and 5 Gy. This resulted in cellular responses, which are typically observed also in naïve T-lymphocytes in response of T-cell receptor immune stimulation or mitogens. These responses include oscillations of cytosolic Ca 2+ , an upregulation of CD25 surface expression, interleukin-2 and interferon-γ synthesis, elevated expression of Ca 2+ sensitive K + channels and an increase in cell diameter. The latter was sensitive to inhibition by the immunosuppressant cyclosporine A, Ca 2+ buffer BAPTA-AM, and the CDK1-inhibitor RO3306, indicating the involvement of Ca 2+ -dependent immune activation and radiation-induced cell cycle arrest. Furthermore, on a functional level, Jurkat and PBL cell adhesion to endothelial cells was increased upon radiation exposure and was highly dependent on an upregulation of integrin beta-1 expression and clustering. In conclusion, we here report that IR impacts on immune activation and functional properties of T-lymphocytes that may have implications in both toxic effects and treatment response to combined radiation and immune therapy in cancer patients.

Evaluation of Radiation Response and Gold Nanoparticle Enhancement in Drug-Resistant Pancreatic Cancer Cells

Science.gov (United States)

Abourabia, Assya

Pancreatic cancer is a major cause of cancer-related death worldwide after lung cancer and colorectal cancer Pancreatic treatment modalities consist of surgery, chemotherapy, and radiation therapy or combination of these therapies. These modalities are good to some extents but they do have some limitations. For example, during the chemotherapy, tumor cells can develop some escape mechanisms and become chemoresistant to protect themselves against the chemo drugs and pass on theses escape mechanisms to their offspring, despite the treatment given. Cancer Cells can become chemoresistant by many mechanisms, for example, decreased drug influx mechanisms, decreased of drug transport molecules, decreased drug activation, altered drug metabolism that diminishes the capacity of cytotoxic drugs, and enhanced repair of DNA damage. Given that some of these chemoresistance mechanisms may impact sensitivity to radiation. Therefore, there is a strong need for a new alternative treatment option to amplify the therapeutic efficacy of radiotherapy and eventually increase the overall efficacy of cancer treatment. Nano-radiation therapy is an emerging and promising modality aims to enhance the therapeutic efficacy of radiotherapy through the use of radiosensitizing nanoparticles. The primary goal of using GNP-enhanced radiation is that GNPs are potent radiosensitizer agents that sensitize the tumor cells to radiation, and these agents promote generation of the free radicals produced by Photo- and Auger- electrons emission at the molecular level which can enhance the effectiveness of radiation-induced cancer cell death. The main aim of this research is to analyze and compare the response to radiation of pancreatic cancer cells, PANC-1, and PANC-1 cells that are resistant to oxaliplatin, PANC-1/OR, and investigate the radiation dose enhancement effect attributable to GNP when irradiating the cells with low-energy (220 kVp) beam at various doses. Based on evidence from the existing

Comparative study of different surrogate markers for individual radiation sensitivity

International Nuclear Information System (INIS)

Hoffmann, Nele Julia

2013-01-01

Radiotherapy is an important part of therapeutic tumor treatment concept. The applied total dose is limited by the unavoidable radiation effect on the surrounding normal tissue and the risk of radiation induced acute or chronic side effects. The clinical radiation sensitivity, i.e. the risk of radiogenic side effects is strongly coupled to the cellular radiation sensitivity. The contribution is focused on the development of a predictive tool for the individual radiation sensitivity for individual radiotherapeutic planning using lymphocytes. Residual foci, i.e. accumulated repair associated proteins at the residual double strand break are supposed to be surrogate markers of the cellular radiation sensitivity. No relation between the foci detection and the G(0)/G(1) was found assay with respect to the individual radiation sensitivity.

Radiation-induced bystander effects enhanced by elevated sodium chloride through sensitizing cells to bystander factors

International Nuclear Information System (INIS)

Zhu Lingyan; Han Wei; Chen Shaopeng; Zhao Ye; Jiang Erkang; Bao Lingzhi; Pei Bei; Yang Gen; Zhao Guoping; Wang Jun; Xu An; Wu Lijun

2008-01-01

Radiation-induced bystander effects (RIBE) have been demonstrated to occur widely in various cell lines. However, very little data is available on the genotoxic effects of RIBE combined with other factor(s). We reported previously that with a low dose of α-particle irradiation, the fraction of γ-H2AX foci-positive cells in non-irradiated bystander cells was significantly increased under elevated NaCl culture conditions. In this study, we further investigated the functional role of NaCl in the enhancement of RIBE using a specially designed co-culture system and micronucleus (MN) test. It was shown that the MN frequency was not increased significantly by elevated NaCl (9.0 g/L) alone or by medium exposure. However, with 1.0 cGy α-particle irradiation, the induced MN frequency increased significantly in both irradiated and non-irradiated bystander regions. Additional studies showed that elevated NaCl made the non-irradiated bystander cells more vulnerable to bystander factors. Furthermore, it was found that the induced MN frequency in cells both in irradiated and non-irradiated bystander regions was weakened when the hypertonic medium was changed to normotonic medium for 2 h before irradiation. Such observations were quite similar to the co-effect of NaCl and hydrogen peroxide (H 2 O 2 ), indicating that elevated NaCl might sensitize non-irradiated cells to bystander factors-induced oxidative stress

The importance of bystander effects in radiation therapy in melanoma skin-cancer cells and umbilical-cord stromal stem cells

International Nuclear Information System (INIS)

Gómez-Millán, Jaime; Katz, Iana Suly Santos; Farias, Virgínea de Araujo; Linares-Fernández, Jose-Luis; López-Peñalver, Jesús; Ortiz-Ferrón, Gustavo; Ruiz-Ruiz, Carmen; Oliver, Francisco Javier; Ruiz de Almodóvar, José Mariano

2012-01-01

Purpose: To examine direct and bystander radiation-induced effects in normal umbilical-cord stromal stem cell (HCSSC) lines and in human cancer cells. Materials and methods: The UCSSC lines used in this study were obtained in our laboratory. Two cell lines (UCSSC 35 and UCSSC 37) and two human melanoma skin-cancer cells (A375 and G361) were exposed to ionizing radiation to measure acute radiation-dosage cell-survival curves and radiation-induced bystander cell-death response. Normal cells, although extremely sensitive to ionizing radiation, were resistant to the bystander effect whilst tumor cells were sensitive to irradiated cell-conditioned media, showing a dose–response relationship that became saturated at relatively low doses. We applied a biophysical model to describe bystander cell-death through the binding of a ligand to the cells. This model allowed us to calculate the maximum cell death (χ max ) produced by the bystander effect together with its association constant (K By ) in terms of dose equivalence (Gy). The values obtained for K By in A375 and G361 cells were 0.23 and 0.29 Gy, respectively. Conclusion: Our findings help to understand how anticancer therapy could have an additional decisive effect in that the response of sub-lethally hit tumor cells to damage might be required for therapy to be successful because the survival of cells communicating with irradiated cells is reduced.

Targeting Nucleophosmin 1 Represents a Rational Strategy for Radiation Sensitization

Energy Technology Data Exchange (ETDEWEB)

Sekhar, Konjeti R. [Department of Radiation Oncology, Vanderbilt University School of Medicine, Nashville, Tennessee (United States); Benamar, Mouadh [Department of Radiation Oncology, University of Virginia School of Medicine, Charlottesville, Virginia (United States); Venkateswaran, Amudhan; Sasi, Soumya [Department of Radiation Oncology, Vanderbilt University School of Medicine, Nashville, Tennessee (United States); Penthala, Narsimha R.; Crooks, Peter A. [Department of Pharmaceutical Sciences, College of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, Arkansas (United States); Hann, Stephen R. [Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee (United States); Geng, Ling [Department of Radiation Oncology, Vanderbilt University School of Medicine, Nashville, Tennessee (United States); Balusu, Ramesh [Department of Internal Medicine, University of Kansas Medical Center, Kansas City, Kansas (United States); Abbas, Tarek [Department of Radiation Oncology, University of Virginia School of Medicine, Charlottesville, Virginia (United States); Freeman, Michael L., E-mail: michael.freeman@vanderbilt.edu [Department of Radiation Oncology, Vanderbilt University School of Medicine, Nashville, Tennessee (United States)

2014-08-01

Purpose: To test the hypothesis that small molecule targeting of nucleophosmin 1 (NPM1) represents a rational approach for radiosensitization. Methods and Materials: Wilde-type and NPM1-deficient mouse embryo fibroblasts (MEFs) were used to determine whether radiosensitization produced by the small molecule YTR107 was NPM1 dependent. The stress response to ionizing radiation was assessed by quantifying pNPM1, γH2AX, and Rad51 foci, neutral comet tail moment, and colony formation. NPM1 levels in a human-derived non-small-cell lung cancer (NSCLC) tissue microarray (TMA) were determined by immunohistochemistry. YTR107-mediated radiosensitization was assessed in NSCLC cell lines and xenografts. Results: Use of NPM1-null MEFs demonstrated that NPM1 is critical for DNA double- strand break (DSB) repair, that loss of NPM1 increases radiation sensitivity, and that YTR107-mediated radiosensitization is NPM1 dependent. YTR107 was shown to inhibit NPM1 oligomerization and impair formation of pNPM1 irradiation-induced foci that colocalized with γH2AX foci. Analysis of the TMA demonstrated that NPM1 is overexpressed in subsets of NSCLC. YTR107 inhibited DNA DSB repair and radiosensitized NSCLC lines and xenografts. Conclusions: These data demonstrate that YTR107-mediated targeting of NPM1 impairs DNA DSB repair, an event that increases radiation sensitivity.

Targeting Nucleophosmin 1 Represents a Rational Strategy for Radiation Sensitization

International Nuclear Information System (INIS)

Sekhar, Konjeti R.; Benamar, Mouadh; Venkateswaran, Amudhan; Sasi, Soumya; Penthala, Narsimha R.; Crooks, Peter A.; Hann, Stephen R.; Geng, Ling; Balusu, Ramesh; Abbas, Tarek; Freeman, Michael L.

2014-01-01

Purpose: To test the hypothesis that small molecule targeting of nucleophosmin 1 (NPM1) represents a rational approach for radiosensitization. Methods and Materials: Wilde-type and NPM1-deficient mouse embryo fibroblasts (MEFs) were used to determine whether radiosensitization produced by the small molecule YTR107 was NPM1 dependent. The stress response to ionizing radiation was assessed by quantifying pNPM1, γH2AX, and Rad51 foci, neutral comet tail moment, and colony formation. NPM1 levels in a human-derived non-small-cell lung cancer (NSCLC) tissue microarray (TMA) were determined by immunohistochemistry. YTR107-mediated radiosensitization was assessed in NSCLC cell lines and xenografts. Results: Use of NPM1-null MEFs demonstrated that NPM1 is critical for DNA double- strand break (DSB) repair, that loss of NPM1 increases radiation sensitivity, and that YTR107-mediated radiosensitization is NPM1 dependent. YTR107 was shown to inhibit NPM1 oligomerization and impair formation of pNPM1 irradiation-induced foci that colocalized with γH2AX foci. Analysis of the TMA demonstrated that NPM1 is overexpressed in subsets of NSCLC. YTR107 inhibited DNA DSB repair and radiosensitized NSCLC lines and xenografts. Conclusions: These data demonstrate that YTR107-mediated targeting of NPM1 impairs DNA DSB repair, an event that increases radiation sensitivity

Butyrate down regulates BCL-XL and sensitizes human fibroblasts to radiation and chemotherapy induced apoptosis

International Nuclear Information System (INIS)

Chung, Diana H.; Ljungman, Mats; Zhang Fenfen; Chen Feng; McLaughlin, William P.

1997-01-01

Purpose/Objective: Butyrate is a short chain fatty acid that has been implicated in the induction of cell cycle arrest, cell differentiation and apoptosis. The purpose of this study was to determine if butyrate treatment sensitizes cells to radiation or chemotherapy induced apoptosis. Materials and Methods: Normal neonatal human diploid fibroblasts were used throughout this study. Apoptosis was scored and quantified using three different methods. First, cell morphology using propidium iodide and fluorescence microscopy was used to qualitatively determine apoptosis and to quantify the percentage of cells undergoing apoptosis. Second, apoptosis induced DNA degradation was scored by quantifying the amount of cells appearing in a sub-G1 peak using fixed and PI-stained cells and flow cytometry. Third, apoptosis-induced DNA degradation was examined by using an assay involving direct lysis of cells in the wells of agarose gels followed by conventional gel electrophoresis. Western blotting was used to quantify the cellular levels of the apoptosis regulators, Bcl-2, Bcl-XL and Bax. Results: Human diploid fibroblasts, which were resistant to radiation induced apoptosis, were found to undergo massive apoptosis when radiation was combined with butyrate treatment. Sensitization was obtained when butyrate was added before or after radiation although the combination of both pre and post-treatment was the most effective. Butyrate was also found to enhance UV light and cisplatin-induced apoptosis. These findings correlated with a reduction of the apoptosis antagonist Bcl-XL. Bcl-XL levels significantly dropped in a time and dose dependent manner. In addition, butyrate effectively blocked UV-induced accumulation of p53. Conclusion: Our results suggest that butyrate may be an attractive agent to use in combination with radiation or chemotherapy to lower the apoptotic threshold of tumor cells, regardless of the p53 status of the tumor cells

Radiation-induced inhibition of human endothelial cells replicating in culture

International Nuclear Information System (INIS)

DeGowin, R.L.; Lewis, L.J.; Mason, R.E.; Borke, M.K.; Hoak, J.C.

1976-01-01

The radiosensitivity of some tumors may depend upon the sensitivity of their microvasculature to radiation. Heretofore, the dose-response of human endothelial cells replicating in tissue culture has not been published. In studies reported here, we exposed flasks containing 4 to 7 x 10 4 genetically identical human endothelial cells to doses of x irradiation from 125 to 1000 rad. During the phase of logarithmic growth, cell counts were compared to those of an unirradiated control to construct a dose--response curve. Similar studies were performed with normal fibroblasts. We found that 160 rad suppressed endothelial cell replication by 37 percent. Although recovery was evident with doses of 500 rad, no net increase in cell number occurred in 3 weeks in flasks of endothelial cells that received 750 or 1000 rad. Fibroblasts were slightly less sensitive under these conditions. To our knowledge, this is the first report of a radiation dose--response curve for human endothelial cells replicating in culture

MicroRNA-223 Enhances Radiation Sensitivity of U87MG Cells In Vitro and In Vivo by Targeting Ataxia Telangiectasia Mutated

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Liang, Liping; Zhu, Ji [Departments of Radiation Oncology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai (China); Zaorsky, Nicholas G. [Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania (United States); Deng, Yun [Departments of Radiation Oncology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai (China); Wu, Xingzhong [Department of Biochemistry and Molecular Biology, Shanghai Medical College, Fudan University, Shanghai (China); Liu, Yong [Departments of Radiation Oncology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai (China); Liu, Fangqi; Cai, Guoxiang; Gu, Weilie [Department of Colorectal Cancer, Fudan University, Shanghai Cancer Center, Shanghai (China); Shen, Lijun [Departments of Radiation Oncology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai (China); Zhang, Zhen, E-mail: zhenzhang6@hotmail.com [Departments of Radiation Oncology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai (China)

2014-03-15

Purpose: Ataxia telangiectasia mutated (ATM) protein is important in the DNA damage response because it repairs radiation-induced damage in cancers. We examined the effect of microRNA-223 (miR-223), a regulator of ATM expression, on radiation sensitivity of cancer cells. Methods and Materials: Human embryonic kidney 293 T (293T) cells were infected with pLL3.7-miR-223 plasmid to generate the pLL3.7-miR-223 and -empty virus (EV) lentivirus (miR-223 and EV). A dual luciferase assay in which the reporter contained wild-type 3′ untranslated region (UTR) of ATM was performed. U87MG cells were infected with miR-223 or EV to establish the overexpressed stable cell lines (U87-223 or U87-EV, respectively). Cells were irradiated in vitro, and dose enhancement ratios at 2 Gy (DER{sub 2}) were calculated. Hind legs of BALB/c athymic mice were injected with U87-223 or U87-EV cells; after 2 weeks, half of the tumors were irradiated. Tumor volumes were tracked for a total of 5 weeks. Results: The dual luciferase reporter assay showed a significant reduction in luciferase activity of 293T cells cotransfected with miR-223 and the ATM 3′UTR compared to that in EV control. Overexpression of miR-223 in U87MG cells showed that ATM expression was significantly downregulated in the U87-223 cells compared to that in U87-EV (ATM/β-actin mRNA 1.0 vs 1.5, P<.05). U87-223 cells were hypersensitive to radiation compared to U87-EV cells in vitro (DER{sub 2} = 1.32, P<.01). Mice injected with miR-223-expressing tumors had almost the same tumors after 3 weeks (1.5 cm{sup 3} vs 1.7 cm{sup 3}). However, irradiation significantly decreased tumor size in miR-223-expressing tumors compared to those in controls (0.033 cm{sup 3} vs 0.829 cm{sup 3}). Conclusions: miR-223 overexpression downregulates ATM expression and sensitizes U87 cells to radiation in vitro and in vivo. MicroRNA-223 may be a novel cancer-targeting therapy, although its cancer- and patient-specific roles are

Radiation-induced Genomic Instability and Radiation Sensitivity

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Varnum, Susan M.; Sowa, Marianne B.; Kim, Grace J.; Morgan, William F.

2013-01-19

The obvious relationships between reactive oxygen and nitrogen species, mitochondrial dysfunction, inflammatory type responses and reactive chemokines and cytokines suggests a general stress response induced by ionizing radiation most likely leads to the non-targeted effects described after radiation exposure. We argue that true bystander effects do not occur in the radiation therapy clinic. But there is no question that effects outside the target volume do occur. These “out of field effects” are considered very low dose effects in the context of therapy. So what are the implications of non-targeted effects on radiation sensitivity? The primary goal of therapy is to eradicate the tumor. Given the genetic diversity of the human population, lifestyle and environment factors it is likely some combination of these will influence patient outcome. Non-targeted effects may contribute to a greater or lesser extent. But consider the potential situation involving a partial body exposure due to a radiation accident or radiological terrorism. Non-targeted effects suggest that the tissue at risk for demonstrating possible detrimental effects of radiation exposure might be greater than the volume actually irradiated.

Ionizing Radiation Induces Morphological Changes and Immunological Modulation of Jurkat Cells

Directory of Open Access Journals (Sweden)

Patrick Voos

2018-04-01

Full Text Available Impairment or stimulation of the immune system by ionizing radiation (IR impacts on immune surveillance of tumor cells and non-malignant cells and can either foster therapy response or side effects/toxicities of radiation therapy. For a better understanding of the mechanisms by which IR modulates T-cell activation and alters functional properties of these immune cells, we exposed human immortalized Jurkat cells and peripheral blood lymphocytes (PBL to X-ray doses between 0.1 and 5 Gy. This resulted in cellular responses, which are typically observed also in naïve T-lymphocytes in response of T-cell receptor immune stimulation or mitogens. These responses include oscillations of cytosolic Ca2+, an upregulation of CD25 surface expression, interleukin-2 and interferon-γ synthesis, elevated expression of Ca2+ sensitive K+ channels and an increase in cell diameter. The latter was sensitive to inhibition by the immunosuppressant cyclosporine A, Ca2+ buffer BAPTA-AM, and the CDK1-inhibitor RO3306, indicating the involvement of Ca2+-dependent immune activation and radiation-induced cell cycle arrest. Furthermore, on a functional level, Jurkat and PBL cell adhesion to endothelial cells was increased upon radiation exposure and was highly dependent on an upregulation of integrin beta-1 expression and clustering. In conclusion, we here report that IR impacts on immune activation and functional properties of T-lymphocytes that may have implications in both toxic effects and treatment response to combined radiation and immune therapy in cancer patients.

Effects of radiation and chemical substances on cells and organism

International Nuclear Information System (INIS)

Fremuth, F.

1981-01-01

The book treats the radiation chemistry part of biophysics and applied biophysics in the sphere of ionizing radiation. Discussed are the concepts of radiation units and radioactivity units and the relative biological efficiency. The effects of ionizing and UV radiations are analyzed at the level of macromolecular changes. Chapters dealing with genetic radiation effects discuss the effects at the cellular level with respect to cell proliferation. All these problems are used to illustrate the effect on the organism as a whole. The chapters on applied biophysics deal with the indications of radiation and chemical damage, sensitivity of cells and the organism, and the study and influencing of growth at the cellular level. The concluding chapter is devoted to the environmental impact of radiation. (J.P.)

Regulation of the oxidative balance with coenzyme Q10 sensitizes human glioblastoma cells to radiation and temozolomide.

Science.gov (United States)

Frontiñán-Rubio, Javier; Santiago-Mora, Raquel María; Nieva-Velasco, Consuelo María; Ferrín, Gustavo; Martínez-González, Alicia; Gómez, María Victoria; Moreno, María; Ariza, Julia; Lozano, Eva; Arjona-Gutiérrez, Jacinto; Gil-Agudo, Antonio; De la Mata, Manuel; Pesic, Milica; Peinado, Juan Ramón; Villalba, José M; Pérez-Romasanta, Luis; Pérez-García, Víctor M; Alcaín, Francisco J; Durán-Prado, Mario

2018-05-18

To investigate how the modulation of the oxidative balance affects cytotoxic therapies in glioblastoma, in vitro. Human glioblastoma U251 and T98 cells and normal astrocytes C8D1A were loaded with coenzyme Q10 (CoQ). Mitochondrial superoxide ion (O 2 - ) and H 2 O 2 were measured by fluorescence microscopy. OXPHOS performance was assessed in U251 cells with an oxytherm Clark-type electrode. Radio- and chemotherapy cytotoxicity was assessed by immunostaining of γH2AX (24 h), annexin V and nuclei morphology, at short (72 h) and long (15 d) time. Hif-1α, SOD1, SOD2 and NQO1 were determined by immunolabeling. Catalase activity was measured by classic enzymatic assay. Glutathione levels and total antioxidant capacity were quantified using commercial kits. CoQ did not affect oxygen consumption but reduced the level of O 2 - and H 2 O 2 while shifted to a pro-oxidant cell status mainly due to a decrease in catalase activity and SOD2 level. Hif-1α was dampened, echoed by a decrease lactate and several key metabolites involved in glutathione synthesis. CoQ-treated cells were twofold more sensitive than control to radiation-induced DNA damage and apoptosis in short and long-term clonogenic assays, potentiating TMZ-induced cytotoxicity, without affecting non-transformed astrocytes. CoQ acts as sensitizer for cytotoxic therapies, disarming GBM cells, but not normal astrocytes, against further pro-oxidant injuries, being potentially useful in clinical practice for this fatal pathology. Copyright © 2018 Elsevier B.V. All rights reserved.

WE-FG-BRA-11: Theranostic Platinum Nanoparticle for Radiation Sensitization in Breast Cancer Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Yue, Y; Wagner, S; Medina-Kauwe, L; Cui, X; Zhang, G; Shiao, S; Sandler, H; Fraass, B [Cedars Sinai Medical Center, Los Angeles, CA (United States)

2016-06-15

Purpose: We have developed a novel receptor-targeted theranostic platinum nanoparticle (HER-PtNP) for enhanced radiation sensitization in HER2-positive breast cancer radiation treatment. This study aims to evaluate receptor-targeting specificity, and radiation sensitization of the nanoparticle. Methods: The platinum nanoparticle (PtNP) was synthesized with the diameter of 2nm, and capped with cysteine. The nanoparticle was tagged with a fluorescent dye (cy5) for the fluoresence detection, and conjuated with HER2/3 targeted protein (HerPBK10) for HER2-targeting specificity. We evaluated the theranostic features using in vitro breast cancer cell models: HER2-positive BT-474, and HER2-negative MDA-MB-231. The HER2-targeting specificity was evaluated using immunofluorescence and confocal microscopy. For each cell line, three sets of samples, including non-stained control, fluorescence stained PtNP-cy5 treated, and HER-PtNP treated, were imaged by confocal microscopy. Two breast cancer cell lineages were incubated with PtNP and HER-PtNP at 10 µg/mL, and then irradiated with X-rays for 2 Gy dose at 50 kVp. A colonogenic assay was used to determine cellular survival fractions by immediately reseeding 300 cells after irradiation in growth media and allowing colonies to grow for 2 weeks. Results: The results of confocal images show that no apparent nanoparticle cellular uptake was observed in the HER2-(MDA-MB-231) cells with 1% for PtNP-cy5 and 0.5% for HER-PtNP. Similarly no apparent PtNP-cy5 uptake (<1%) for BT474 cells was observed. However, there was significant HER-PtNP uptake (73%) for the HER2+(BT474) cells. The clonogenic assay showed that BT474 cells treated with HER-PtNP had significantly lower survival compared to those treated with PtNP (32% vs 81%, p=0.01). However, no significant radiosensitivity enhancement was observed for MDA-MB-231 cell treated with PtNP and HER-PtNP (89% vs 92%, p=0.78). Conclusion: Our studies suggest that the HER2-targeted platinum

WE-FG-BRA-11: Theranostic Platinum Nanoparticle for Radiation Sensitization in Breast Cancer Radiotherapy

International Nuclear Information System (INIS)

Yue, Y; Wagner, S; Medina-Kauwe, L; Cui, X; Zhang, G; Shiao, S; Sandler, H; Fraass, B

2016-01-01

Purpose: We have developed a novel receptor-targeted theranostic platinum nanoparticle (HER-PtNP) for enhanced radiation sensitization in HER2-positive breast cancer radiation treatment. This study aims to evaluate receptor-targeting specificity, and radiation sensitization of the nanoparticle. Methods: The platinum nanoparticle (PtNP) was synthesized with the diameter of 2nm, and capped with cysteine. The nanoparticle was tagged with a fluorescent dye (cy5) for the fluoresence detection, and conjuated with HER2/3 targeted protein (HerPBK10) for HER2-targeting specificity. We evaluated the theranostic features using in vitro breast cancer cell models: HER2-positive BT-474, and HER2-negative MDA-MB-231. The HER2-targeting specificity was evaluated using immunofluorescence and confocal microscopy. For each cell line, three sets of samples, including non-stained control, fluorescence stained PtNP-cy5 treated, and HER-PtNP treated, were imaged by confocal microscopy. Two breast cancer cell lineages were incubated with PtNP and HER-PtNP at 10 µg/mL, and then irradiated with X-rays for 2 Gy dose at 50 kVp. A colonogenic assay was used to determine cellular survival fractions by immediately reseeding 300 cells after irradiation in growth media and allowing colonies to grow for 2 weeks. Results: The results of confocal images show that no apparent nanoparticle cellular uptake was observed in the HER2-(MDA-MB-231) cells with 1% for PtNP-cy5 and 0.5% for HER-PtNP. Similarly no apparent PtNP-cy5 uptake (<1%) for BT474 cells was observed. However, there was significant HER-PtNP uptake (73%) for the HER2+(BT474) cells. The clonogenic assay showed that BT474 cells treated with HER-PtNP had significantly lower survival compared to those treated with PtNP (32% vs 81%, p=0.01). However, no significant radiosensitivity enhancement was observed for MDA-MB-231 cell treated with PtNP and HER-PtNP (89% vs 92%, p=0.78). Conclusion: Our studies suggest that the HER2-targeted platinum

Distinctions in sensitivity and repair of cells of children with some hereditary diseases

International Nuclear Information System (INIS)

Zasukhina, G.D.; Barashnev, Yu.I.; Vasil'eva, I.M.; Sdirkova, N.I.; Semyachkina, A.N.

1982-01-01

A study was made of blood cell sensitivity of children, with some hereditary diseases, to ν-radiation and 4-nitro-quinoline-1-oxide. Using the host cell reactivation and chromatographic methods we revealed the increase in the sensitivity to the above mentioned agents and inhibition of the repair function in cells of patients with the following diseases: Marfan's disease, histidinemia, osteogenesis imperfecta, Sylvere-Russelle, Laurence, Franchescetti, and Losch-Nychane syndromes

Radiation-sensitive mutant of hypertoxinogenic strain 569B of Vibro cholerae

International Nuclear Information System (INIS)

Das, G.; Das, J.

1983-01-01

A radiation-sensitive mutant of the hypertoxinogenic strain 569B of Vibrio cholerae was isolated and characterized. The mutant, designated V. cholerae 569Bsub(s), lacks both excision- and medium-dependent dark-repair mechanisms of UV-induced DNA damage while retaining the wild-type photoreactivating capability. Analysis of the UV-irradiated cell DNA by velocity sedimentation in alkaline sucrose gradient suggests that UV-induced pyrimidine dimers may not be incised in these cells. In contrast to the wild-type cells, the mutant cell DNA was degraded after treatment with nalidixic acid. The mutant cells failed to produce any detectable amount of cholera toxin as measured by ileal-loop assay. (orig.)

Regulation of radiation-induced protein kinase Cδ activation in radiation-induced apoptosis differs between radiosensitive and radioresistant mouse thymic lymphoma cell lines

International Nuclear Information System (INIS)

Nakajima, Tetsuo; Yukawa, Osami; Tsuji, Hideo; Ohyama, Harumi; Wang, Bing; Tatsumi, Kouichi; Hayata, Isamu; Hama-Inaba, Hiroko

2006-01-01

Protein kinase Cδ (PKCδ) has an important role in radiation-induced apoptosis. The expression and function of PKCδ in radiation-induced apoptosis were assessed in a radiation-sensitive mouse thymic lymphoma cell line, 3SBH5, and its radioresistant variant, XR223. Rottlerin, a PKCδ-specific inhibitor, completely abolished radiation-induced apoptosis in 3SBH5. Radiation-induced PKCδ activation correlated with the degradation of PKCδ, indicating that PKCδ activation through degradation is involved in radiation-induced apoptosis in radiosensitive 3SBH5. In radioresistant XR223, radiation-induced PKCδ activation was lower than that in radiosensitive 3SBH5. Cytosol PKCδ levels in 3SBH5 decreased markedly after irradiation, while those in XR223 did not. There was no apparent change after irradiation in the membrane fractions of either cell type. In addition, basal cytosol PKCδ levels in XR223 were higher than those in 3SBH5. These results suggest that the radioresistance in XR223 to radiation-induced apoptosis is due to a difference in the regulation of radiation-induced PKCδ activation compared to that of 3SBH5. On the other hand, Atm -/- mouse thymic lymphoma cells were more radioresistant to radiation-induced apoptosis than wild-type mouse thymic lymphoma cells. Irradiated wild-type cells, but not Atm -/- cells, had decreased PKCδ levels, indicating that the Atm protein is involved in radiation-induced apoptosis through the induction of PKCδ degradation. The decreased Atm protein levels induced by treatment with Atm small interfering RNA had no effect on radiation-induced apoptosis in 3SBH5 cells. These results suggest that the regulation of radiation-induced PKCδ activation, which is distinct from the Atm-mediated cascade, determines radiation sensitivity in radiosensitive 3SBH5 cells

Characterization of radiation-induced Apoptosis in rodent cell lines

International Nuclear Information System (INIS)

Guo, Min; Chen, Changhu; Ling, C.C.

1997-01-01

For REC:myc(ch1), Rat1 and Rat1:myc b cells, we determined the events in the development of radiation-induced apoptosis to be in the following order: cell division followed by chromatin condensation, membrane blebbing, loss of adhesion and the uptake of vital dye. Experimental data which were obtained using 4 He ions of well defined energies and which compared the dependence of apoptosis and clonogenic survival on 4 He range strongly suggested that in our cells both apoptosis and loss of clonogenic survival resulted from radiation damage to the cell nucleus. Corroboratory evidence was that BrdU incorporation sensitized these cells to radiation-induced apoptosis. Comparing the dose response for apoptosis and the clonogenic survival curves for Rat1 and Rat1:myc b cells, we concluded that radiation-induced cell inactivation as assayed by clonogenic survival, and that a modified linear-quadratic model, proposed previously, modeled such a contribution effectively. In the same context, the selective increase in radiation-induced apoptosis. Comparing the dose response for apoptosis and the clonogenic survival curves for Rat1 and Rat1:myc b cells, we concluded that radiation-induced apoptosis contributed to the overall radiation-induced cell inactivation as assayed by clonogenic survival, and that a modified linear-quadratic model, proposed previously, modeled such a contribution effectively. In the same context, the selective increase in radiation-induced apoptosis during late S and G 2 phases reduced the relative radioresistance observed for clonogenic survival during late S and G 2 phases. 30 refs., 8 figs

Radiation sensitive devices and systems for detection of radioactive materials and related methods

Science.gov (United States)

Kotter, Dale K

2014-12-02

Radiation sensitive devices include a substrate comprising a radiation sensitive material and a plurality of resonance elements coupled to the substrate. Each resonance element is configured to resonate responsive to non-ionizing incident radiation. Systems for detecting radiation from a special nuclear material include a radiation sensitive device and a sensor located remotely from the radiation sensitive device and configured to measure an output signal from the radiation sensitive device. In such systems, the radiation sensitive device includes a radiation sensitive material and a plurality of resonance elements positioned on the radiation sensitive material. Methods for detecting a presence of a special nuclear material include positioning a radiation sensitive device in a location where special nuclear materials are to be detected and remotely interrogating the radiation sensitive device with a sensor.

Folic acid deficiency increases chromosomal instability, chromosome 21 aneuploidy and sensitivity to radiation-induced micronuclei

International Nuclear Information System (INIS)

Beetstra, Sasja; Thomas, Philip; Salisbury, Carolyn; Turner, Julie; Fenech, Michael

2005-01-01

Folic acid deficiency can lead to uracil incorporation into DNA, hypomethylation of DNA, inefficient DNA repair and increase chromosome malsegregation and breakage. Because ionising radiation increases demand for efficient DNA repair and also causes chromosome breaks we hypothesised that folic acid deficiency may increase sensitivity to radiation-induced chromosome breakage. We tested this hypothesis by using the cytokinesis-block micronucleus assay in 10 day WIL2-NS cell cultures at four different folic acid concentrations (0.2, 2, 20, and 200 nM) that span the 'normal' physiological range in humans. The study showed a significant dose-dependent increase in frequency of binucleated cells with micronuclei and/or nucleoplasmic bridges with decreasing folic acid concentration (P < 0.0001, P = 0.028, respectively). These biomarkers of chromosomal instability were also increased in cells irradiated (1.5 Gy γ-rays) on day 9 relative to un-irradiated controls (P < 0.05). Folic acid deficiency and γ-irradiation were shown to have a significant interactive effect on frequency of cells containing micronuclei (two-way ANOVA, interaction P 0.0039) such that the frequency of radiation-induced micronucleated cells (i.e. after subtracting base-line frequency of un-irradiated controls) increased with decreasing folic acid concentration (P-trend < 0.0001). Aneuploidy of chromosome 21, apoptosis and necrosis were increased by folic acid deficiency but not by ionising radiation. The results of this study show that folate status has an important impact on chromosomal stability and is an important modifying factor of cellular sensitivity to radiation-induced genome damage

Tumourigenicity and radiation resistance of mesenchymal stem cells.

Science.gov (United States)

D'Andrea, Filippo P; Horsman, Michael R; Kassem, Moustapha; Overgaard, Jens; Safwat, Akmal

2012-05-01

Cancer stem cells are believed to be more radiation resistant than differentiated tumour cells of the same origin. It is not known, however, whether normal nontransformed adult stem cells share the same radioresistance as their cancerous counterpart. Nontumourigenic (TERT4) and tumourigenic (TRET20) cell lines, from an immortalised mesenchymal stem cell line, were grown in culture prior to irradiation and gene expression analysis. Radiation resistance was measured using a clonogenic assay. Differences in gene expression between the two cell lines, both under nontreated and irradiated conditions, were assessed with microarrays (Affymetrix Human Exon 1.0 ST array). The cellular functions affected by the altered gene expressions were assessed through gene pathway mapping (Ingenuity Pathway Analysis). Based on the clonogenic assay the nontumourigenic cell line was found to be more sensitive to radiation than the tumourigenic cell line. Using the exon chips, 297 genes were found altered between untreated samples of the cell lines whereas only 16 genes responded to radiation treatment. Among the genes with altered expression between the untreated samples were PLAU, PLAUR, TIMP3, MMP1 and LOX. The pathway analysis based on the alteration between the untreated samples indicated cancer and connective tissue disorders. This study has shown possible common genetic events linking tumourigenicity and radiation response. The PLAU and PLAUR genes are involved in apoptosis evasion while the genes TIMP3, MMP1 and LOX are involved in regulation of the surrounding matrix. The first group may contribute to the difference in radiation resistance observed and the latter could be a major contributor to the tumourigenic capabilities by degrading the intercellular matrix. These results also indicate that cancer stem cells are more radiation resistant than stem cells of the same origin.

Radiation-induced bystander effects enhanced by elevated sodium chloride through sensitizing cells to bystander factors

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Zhu Lingyan; Han Wei; Chen Shaopeng; Zhao Ye; Jiang Erkang; Bao Lingzhi; Pei Bei; Yang Gen; Zhao Guoping; Wang Jun; Xu An [Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei 230031, Anhui (China); Wu Lijun [Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei 230031, Anhui (China)], E-mail: ljw@ipp.ac.cn

2008-09-26

Radiation-induced bystander effects (RIBE) have been demonstrated to occur widely in various cell lines. However, very little data is available on the genotoxic effects of RIBE combined with other factor(s). We reported previously that with a low dose of {alpha}-particle irradiation, the fraction of {gamma}-H2AX foci-positive cells in non-irradiated bystander cells was significantly increased under elevated NaCl culture conditions. In this study, we further investigated the functional role of NaCl in the enhancement of RIBE using a specially designed co-culture system and micronucleus (MN) test. It was shown that the MN frequency was not increased significantly by elevated NaCl (9.0 g/L) alone or by medium exposure. However, with 1.0 cGy {alpha}-particle irradiation, the induced MN frequency increased significantly in both irradiated and non-irradiated bystander regions. Additional studies showed that elevated NaCl made the non-irradiated bystander cells more vulnerable to bystander factors. Furthermore, it was found that the induced MN frequency in cells both in irradiated and non-irradiated bystander regions was weakened when the hypertonic medium was changed to normotonic medium for 2 h before irradiation. Such observations were quite similar to the co-effect of NaCl and hydrogen peroxide (H{sub 2}O{sub 2}), indicating that elevated NaCl might sensitize non-irradiated cells to bystander factors-induced oxidative stress.

Influence of chemical inhibitors on cell recovery after exposure to different LET radiation

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Evstratova, Ekaterina S.; Petin, Vladislav G. [Medical Radiological Research Center, Obninsk (Russian Federation); Kim, Jin Kyu; KIm, Jin Hong [Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

2016-12-15

Chemical radiosensitizers are often used to increase cell radiosensitivity. It is known that the ability of chemical drugs to increase cell radiosensitivity is related with inhibition of cell recovery from damage induced by ionizing radiation. However, there are little comparative investigations of cell sensitivity modification after exposure to radiation with high linear energy transfer (LET). Therefore, we studied the anticancer drugs cisplatin and endoxan and their impact on the ability of yeast cells to recover after cell exposure to radiations with different LET. The ability of cell recovery from radiation damage was less effective after exposure to high-LET radiation, when cells were irradiated without drug, with the increase in cisplatin concentration resulting in the disappearance of this difference. The increase of cisplatin concentration results in progressive increase in the fraction of irreversible damage independently of radiation quality.

Influence of chemical inhibitors on cell recovery after exposure to different LET radiation

International Nuclear Information System (INIS)

Evstratova, Ekaterina S.; Petin, Vladislav G.; Kim, Jin Kyu; KIm, Jin Hong

2016-01-01

Chemical radiosensitizers are often used to increase cell radiosensitivity. It is known that the ability of chemical drugs to increase cell radiosensitivity is related with inhibition of cell recovery from damage induced by ionizing radiation. However, there are little comparative investigations of cell sensitivity modification after exposure to radiation with high linear energy transfer (LET). Therefore, we studied the anticancer drugs cisplatin and endoxan and their impact on the ability of yeast cells to recover after cell exposure to radiations with different LET. The ability of cell recovery from radiation damage was less effective after exposure to high-LET radiation, when cells were irradiated without drug, with the increase in cisplatin concentration resulting in the disappearance of this difference. The increase of cisplatin concentration results in progressive increase in the fraction of irreversible damage independently of radiation quality.

Effects of peroxide and catalase on near ultraviolet radiation sensitivity in Escherichia coli strains

International Nuclear Information System (INIS)

Coombs, A.M.L.; Moss, S.H.

1987-01-01

The role of peroxide and catalase on NUV radiation sensitivity was examined in two repair competent E. coli strains, AB1157 and B/r. Exponential phase B/r is considerably more sensitive to NUV radiation than exponential phase AB1157. However, resistance to 5 mmol dm -3 H 2 O 2 was induced in both AB1157 and B/r by pretreating growing cells with 30 μmol dm -3 H 2 O 2 . Pretreatment also induced resistance to broad-band NUV radiation in these strains. The addition of catalase to the post-irradiation plating medium increased survival to the same extent as that provided by pretreatment with 30 μmol dm -3 H 2 O 2 , in both strains. The NUV radiation sensitivity seen in B/r does not appear to be due to a deficiency in enzymes that scavenge H 2 O 2 , as a catalase deficient mutant, E. coli UM1, is more resistant to NUV radiation than B/r. Also, assays for H 2 O 2 scavenging ability show little difference between AB1157 and B/r in this respect. Two hypotheses are put forward to account for the sensitivity of exponential phase B/r. Whilst it is apparent that peroxides and catalase do have a role in NUV radiation damage, it is clear that other factors also influence survival under certain conditions. (author)

Curcumin sensitizes prostate cancer cells to radiation partly via epigenetic activation of miR-143 and miR-143 mediated autophagy inhibition.

Science.gov (United States)

Liu, Jianbo; Li, Min; Wang, Yuewei; Luo, Jianchao

2017-08-01

Curcumin has been reported as a radiosensitizer in prostate cancer. But the underlying mechanism is not well understood. In this study, we firstly assessed how curcumin affects the expression of miR-143/miR-145 cluster. Then, we investigated whether miR-143 is involved in regulation of radiosensitivity and its association with autophagy in prostate cancer cells. Our data showed that PC3, DU145 and LNCaP cells treated with curcumin had significantly restored miR-143 and miR-145 expression. Curcumin showed similar effect as 5-AZA-dC on reducing methylation of CpG dinucleotides in miR-143 promoter. In addition, curcumin treatment reduced the expression of DNMT1 and DNMT3B, which contribute to promoter hypermethylation of the miR-143/miR-145 cluster. Therefore, we infer that curcumin can restore miR-143 and miR-145 expression via hypomethylation. MiR-143 overexpression and curcumin pretreatment enhanced radiation induced cancer cell growth inhibition and apoptosis. MiR-143 and curcumin remarkably reduced radiation-induced autophagy in PC3 and DU145 cells. MiR-143 overexpression alone also reduced the basal level of autophagy in DU145 cells. Mechanistically, miR-143 can suppress autophagy in prostate cancer cells at least via downregulating ATG2B. Based on these findings, we infer that curcumin sensitizes prostate cancer cells to radiation partly via epigenetic activation of miR-143 and miR-143 mediated autophagy inhibition.

SU-F-T-678: Clotrimazole Sensitizes MCF-7 Breast Cancer Cell Line to Radiation

Energy Technology Data Exchange (ETDEWEB)

Garcia, L; Tambasco, M [San Diego State University, San Diego, CA (United States)

2016-06-15

Purpose: To study the effects of Clotrimazole (CLT) on radiosensitivity of MCF-7 Cells in correlation to detachment of Hexokinase II from the Voltage Dependent Anion Channel on the outer membrane of the mitochondria. Apoptotic fractions were also analyzed in relation to the detachment of Hexokinase. Methods: This study focused on the mammary adenocarcinoma cell line, MCF-7. Colony forming assays were used to analyze radiosensitization by CLT. Flow cytometry methods were used to analyze apoptotic vs necrotic fractions after treatment with CLT. Spectrophotometery was used to analyze the mitochondrial bound and soluble fraction of Hexokinase by means of relative enzymatic activity. Results: Our preliminary data have shown that CLT sensitizes MCF-7 cells to radiation in a dose and incubation time dependent manner up. We have also demonstrated that there are two radiosensitizing periods in MCF-7 cells with the first corresponding to the cycle arrest after 24 hours observed in other cell lines. The second radiosensitizing period occurs with incubation in CLT after irradiation which reaches maximum effect around 24 hours of incubation time. Preliminary data from our Hexokinase detachment assay show a factor of two increase in the ratio of unbound to bound Hexokinase when comparing incubation for 24 hours in media containing 0 and 20 µM CLT. Conclusion: This study and others indicate CLT as a possible radiosensitizing agent in cancer therapies. While CLT itself shows toxicity to the liver in high doses, this study further demonstrates that disruption of the Warburg Effect and unbinding of mitochondrial bound Hexokinase as a possible pathway for cancer treatment.

SU-F-T-678: Clotrimazole Sensitizes MCF-7 Breast Cancer Cell Line to Radiation

International Nuclear Information System (INIS)

Garcia, L; Tambasco, M

2016-01-01

Purpose: To study the effects of Clotrimazole (CLT) on radiosensitivity of MCF-7 Cells in correlation to detachment of Hexokinase II from the Voltage Dependent Anion Channel on the outer membrane of the mitochondria. Apoptotic fractions were also analyzed in relation to the detachment of Hexokinase. Methods: This study focused on the mammary adenocarcinoma cell line, MCF-7. Colony forming assays were used to analyze radiosensitization by CLT. Flow cytometry methods were used to analyze apoptotic vs necrotic fractions after treatment with CLT. Spectrophotometery was used to analyze the mitochondrial bound and soluble fraction of Hexokinase by means of relative enzymatic activity. Results: Our preliminary data have shown that CLT sensitizes MCF-7 cells to radiation in a dose and incubation time dependent manner up. We have also demonstrated that there are two radiosensitizing periods in MCF-7 cells with the first corresponding to the cycle arrest after 24 hours observed in other cell lines. The second radiosensitizing period occurs with incubation in CLT after irradiation which reaches maximum effect around 24 hours of incubation time. Preliminary data from our Hexokinase detachment assay show a factor of two increase in the ratio of unbound to bound Hexokinase when comparing incubation for 24 hours in media containing 0 and 20 µM CLT. Conclusion: This study and others indicate CLT as a possible radiosensitizing agent in cancer therapies. While CLT itself shows toxicity to the liver in high doses, this study further demonstrates that disruption of the Warburg Effect and unbinding of mitochondrial bound Hexokinase as a possible pathway for cancer treatment.

Up-regulation of DNA-dependent protein kinase correlates with radiation resistance in oral squamous cell carcinoma

International Nuclear Information System (INIS)

Shintani, Satoru; Mihara, Mariko; Li, Chunnan; Nakahara Yuuji; Hino, Satoshi; Nakashiro, Koh-ichi; Hamakawa, Hiroyuki

2003-01-01

DNA-PK is a nuclear protein with serine/threonine kinase activity and forms a complex consisting of the DNA-PKcs and a heterodimer of Ku70 and Ku80 proteins. Recent laboratory experiments have demonstrated that the DNA-PK complex formation is one of the major pathways by which mammalian cells respond to DNA double-strand breaks induced by ionizing radiation. In this study, we evaluated the relationship between expression levels of DNA-PKcs, Ku70 and Ku80 proteins and radiation sensitivity in oral squamous cell carcinoma (OSCC) cell lines and in OSCC patients treated with preoperative radiation therapy. The OSCC cell lines greatly differed in their response to irradiation, as assessed by a standard colony formation assay. However, the expression levels of the DNA-PK complex proteins were all similar, and there was no association between the magnitude of their expression and the tumor radiation sensitivity. Expression of DNA-PK complex proteins increased after radiation treatment, and the increased values correlated with the tumor radiation resistance. Expression of DNA-PKcs and Ku70 after irradiation was increased in the surviving cells of OSCC tissues irradiated preoperatively. These results suggest that up-regulation of DNA-PK complex protein, especially DNA-PKcs, after radiation treatment correlates to radiation resistance. DNA-PKcs might be a molecular target for a novel radiation sensitization therapy of OSCC. (author)

Distinctions in sensitivity and repair of cells of children with some hereditary diseases

Energy Technology Data Exchange (ETDEWEB)

Zasukhina, G.D.; Barashnev, Yu.I.; Vasil' eva, I.M.; Sdirkova, N.I.; Semyachkina, A.N. (AN SSSR, Moscow. Inst. Obshchej Genetiki)

A study was made of blood cell sensitivity of children with some hereditary diseases, to ..gamma..-radiation and 4-nitro-quinoline-1-oxide. Using the host cell reactivation and chromatographic methods we revealed the increase in the sensitivity to the above mentioned agents and inhibition of the repair function in cells of patients with the following diseases: Marfan's disease, histidinemia, osteogenesis imperfecta, Sylvere-Russelle, Laurence, Franchescetti, and Losch-Nychane syndromes.

Influence of catalase on the radiation sensitizing effect of misonidazole

International Nuclear Information System (INIS)

Gazso, G.L.; Dam, A.

1985-01-01

The radiation modifying action of misonidazole and catalase was investigated in Bacillus megaterium spores at various oxygen concentrations. Catalase (120 μg/ml) decreased the radiation sensitizing action of misonidazole. Misonidazole as an electron affinic radiation sensitizer enhanced the build up of H 2 O 2 , thus promoting the reaction with catalase. Protection by catalase was not enough to eliminate the total radiation sensitizing effect of misonidazole. (orig.)

Anti-apoptotic peptides protect against radiation-induced cell death

International Nuclear Information System (INIS)

McConnell, Kevin W.; Muenzer, Jared T.; Chang, Kathy C.; Davis, Chris G.; McDunn, Jonathan E.; Coopersmith, Craig M.; Hilliard, Carolyn A.; Hotchkiss, Richard S.; Grigsby, Perry W.; Hunt, Clayton R.

2007-01-01

The risk of terrorist attacks utilizing either nuclear or radiological weapons has raised concerns about the current lack of effective radioprotectants. Here it is demonstrated that the BH4 peptide domain of the anti-apoptotic protein Bcl-xL can be delivered to cells by covalent attachment to the TAT peptide transduction domain (TAT-BH4) and provide protection in vitro and in vivo from radiation-induced apoptotic cell death. Isolated human lymphocytes treated with TAT-BH4 were protected against apoptosis following exposure to 15 Gy radiation. In mice exposed to 5 Gy radiation, TAT-BH4 treatment protected splenocytes and thymocytes from radiation-induced apoptotic cell death. Most importantly, in vivo radiation protection was observed in mice whether TAT-BH4 treatment was given prior to or after irradiation. Thus, by targeting steps within the apoptosis signaling pathway it is possible to develop post-exposure treatments to protect radio-sensitive tissues

Interference with Activator Protein-2 transcription factors leads to induction of apoptosis and an increase in chemo- and radiation- sensitivity in breast cancer cells

LENUS (Irish Health Repository)

Thewes, Verena

2010-05-11

Abstract Background Activator Protein-2 (AP-2) transcription factors are critically involved in a variety of fundamental cellular processes such as proliferation, differentiation and apoptosis and have also been implicated in carcinogenesis. Expression of the family members AP-2α and AP-2γ is particularly well documented in malignancies of the female breast. Despite increasing evaluation of single AP-2 isoforms in mammary tumors the functional role of concerted expression of multiple AP-2 isoforms in breast cancer remains to be elucidated. AP-2 proteins can form homo- or heterodimers, and there is growing evidence that the net effect whether a cell will proliferate, undergo apoptosis or differentiate is partly dependent on the balance between different AP-2 isoforms. Methods We simultaneously interfered with all AP-2 isoforms expressed in ErbB-2-positive murine N202.1A breast cancer cells by conditionally over-expressing a dominant-negative AP-2 mutant. Results We show that interference with AP-2 protein function lead to reduced cell number, induced apoptosis and increased chemo- and radiation-sensitivity. Analysis of global gene expression changes upon interference with AP-2 proteins identified 139 modulated genes (90 up-regulated, 49 down-regulated) compared with control cells. Gene Ontology (GO) investigations for these genes revealed Cell Death and Cell Adhesion and Migration as the main functional categories including 25 and 12 genes, respectively. By using information obtained from Ingenuity Pathway Analysis Systems we were able to present proven or potential connections between AP-2 regulated genes involved in cell death and response to chemo- and radiation therapy, (i.e. Ctgf, Nrp1, Tnfaip3, Gsta3) and AP-2 and other main apoptosis players and to create a unique network. Conclusions Expression of AP-2 transcription factors in breast cancer cells supports proliferation and contributes to chemo- and radiation-resistance of tumor cells by impairing the

Interference with Activator Protein-2 transcription factors leads to induction of apoptosis and an increase in chemo- and radiation-sensitivity in breast cancer cells

International Nuclear Information System (INIS)

Thewes, Verena; Orso, Francesca; Jäger, Richard; Eckert, Dawid; Schäfer, Sabine; Kirfel, Gregor; Garbe, Stephan; Taverna, Daniela; Schorle, Hubert

2010-01-01

Activator Protein-2 (AP-2) transcription factors are critically involved in a variety of fundamental cellular processes such as proliferation, differentiation and apoptosis and have also been implicated in carcinogenesis. Expression of the family members AP-2α and AP-2γ is particularly well documented in malignancies of the female breast. Despite increasing evaluation of single AP-2 isoforms in mammary tumors the functional role of concerted expression of multiple AP-2 isoforms in breast cancer remains to be elucidated. AP-2 proteins can form homo- or heterodimers, and there is growing evidence that the net effect whether a cell will proliferate, undergo apoptosis or differentiate is partly dependent on the balance between different AP-2 isoforms. We simultaneously interfered with all AP-2 isoforms expressed in ErbB-2-positive murine N202.1A breast cancer cells by conditionally over-expressing a dominant-negative AP-2 mutant. We show that interference with AP-2 protein function lead to reduced cell number, induced apoptosis and increased chemo- and radiation-sensitivity. Analysis of global gene expression changes upon interference with AP-2 proteins identified 139 modulated genes (90 up-regulated, 49 down-regulated) compared with control cells. Gene Ontology (GO) investigations for these genes revealed Cell Death and Cell Adhesion and Migration as the main functional categories including 25 and 12 genes, respectively. By using information obtained from Ingenuity Pathway Analysis Systems we were able to present proven or potential connections between AP-2 regulated genes involved in cell death and response to chemo- and radiation therapy, (i.e. Ctgf, Nrp1, Tnfaip3, Gsta3) and AP-2 and other main apoptosis players and to create a unique network. Expression of AP-2 transcription factors in breast cancer cells supports proliferation and contributes to chemo- and radiation-resistance of tumor cells by impairing the ability to induce apoptosis. Therefore, interference

Estramustine: A novel radiation enhancer in human carcinoma cells

International Nuclear Information System (INIS)

Ryu, S.; Gabel, M.; Khil, M.S.

1994-01-01

Estramustine (EM), an antimicrotubule agent, binds microtubule-associated proteins, causes spindle disassembly, and arrests cells at the late G 2 /M phase of the cell cycle. Since cells in the G 2 /M phase are the most radiosensitive and some human cancer cells contain high level of EM-binding protein, experiments were carried out to determine whether radiation sensitization could be obtained in human carcinoma cells. Cells containing a high level of EM-binding protein such as prostate carcinoma (DU-145), breast carcinoma (MCF-7), and malignant glioma (U-251) were used to demonstrate radiosensitization. Cervical carcinoma (HeLa-S 3 ) and colon carcinoma (HT-29) cells which are not known to contain EM-binding protein were also employed. Cell survival was assayed by the colony forming ability of single plated cells in culture to obtain dose-survival curves. Pretreatment of DU-145, MCF-7, and U-251 cells to a nontoxic concentration (5 μM) of EM for more than one cell cycle time, substantially enhanced the radiation-induced cytotoxicity. The sensitizer enhancement ratio of these cells ranged from 1.35-1.52. The magnitude of the enhancement was dependent on the drug concentration and exposure time. The rate of cell accumulation in G 2 /M phase, as determined by flow cytometry, increased with longer treatment time in the cell lines which showed radiosensitization. Other antimicrotubule agents such as taxol and vinblastine caused minimal or no radiosensitization at nontoxic concentrations. The data provide a radiobiological basis for using EM as a novel radiation enhancer, with the property of tissue selectivity. 29 refs., 4 figs., 1 tab

DNA replication and post-replication repair in U.V.-sensitive mouse neuroblastoma cells

International Nuclear Information System (INIS)

Lavin, M.F.; McCombe, P.; Kidson, C.

1976-01-01

Mouse neuroblastoma cells differentiated when grown in the absence of serum; differentiation was reversed on the addition of serum. Differentiated cells were more sensitive to U.V.-radiation than proliferating cells. Whereas addition of serum to differentiated neuroblastoma cells normally resulted in immediate, synchronous entry into S phase, irradiation just before the addition of serum resulted in a long delay in the onset of DNA replication. During this lag period, incorporated 3 H-thymidine appeared in the light density region of CsCl gradients, reflecting either repair synthesis or abortive replication. Post-replication repair (gap-filling) was found to be present in proliferating cells and at certain times in differentiated cells. It is suggested that the sensitivity of differentiated neuroblastoma cells to U.V.-radiation may have been due to ineffective post-replication repair or to deficiencies in more than one repair mechanism, with reduction in repair capacity beyond a critical threshold. (author)

Evaluation of texaphyrins as tumor selective radiation sensitizers

International Nuclear Information System (INIS)

Qing Fan; Woodburn, Kathryn W.; Young, Stuart W.

1997-01-01

Texaphyrins are expanded porphyrin macrocycles that selectively localize and are retained in cancerous lesions. The function of the texaphyrin can be manipulated by the incorporation of different metal ions into the macrocycle's central cavity. Gadolinium texaphyrin (Gd-Tex) and lutetium texaphyrin (Lu-Tex) were evaluated as radiation sensitizers. Radiation sensitization studies were performed using SMT-F and EMT6 mammary tumor-bearing mice. Single and multifraction dose regimens were performed. SMT-F bearing DBA/2N mice and EMT6 bearing Balb/c mice were intravenously administered with Gd-Tex of Lu-Tex (5-40 μmol/kg) 30 minutes to 5 hours prior to radiation (10-50 Gray) for the single fraction studies. The more radioresistant EMT-6 sarcoma model was used for the multifraction studies. The tumor bearing animals were injected with Gd-Tex (5, 20, or 40 μmol/kg) to 2 hours prior radiation (1, 2, or 4 Gray), this regimen was performed for five consecutive days. Gd-Tex is paramagnetic and has a strong fluorescence signal. Tumor selectivity was determined by MRI and fluorescence spectral imaging before and up to 24 hours following the administration of Gd-Tex. Gd-Tex but not Lu-Tex, proved to be an effective radiation sensitizer. Administration of Gd-Tex (40 μmol/kg) prior to a single dose of 30 Gray radiation provided a significant improvement in survival in SMT-F-bearing DBA/2N mice as compared to animals receiving radiation alone (p = 0.0034). A significant radiation sensitization effect was also found in multiple fraction studies (five consecutive days) with Balb/C mice bearing EMT-6 neoplasma-- following 1 Gray of radiation for 5 days there was a significant difference between the 20 and 40 μmol/kg group and controls (p = 0.003, p = 0.005 respectively). MRI and fluorescence spectral imaging studies of tumor bearing animals revealed excellent contrast enhancement of the tumor which persisted up to 24 hours. Texaphyrins localize in neoplasms as visualized using MRI

Radiation-induced apoptosis in sensitive and resistant cells isolated from a mouse lymphoma

International Nuclear Information System (INIS)

Story, M.D.; Voehringer, D.W.; Malone, C.G.; Hobbs, M.L.; Meyn, R.E.

1994-01-01

Cells were isolated from a mouse lymphoma (LY-TH) and grown in vitro. They were susceptible to radiation-induced apoptosis after low doses with the appearance of endonucleolytically fragmented DNA 1 h after irradiation. Four hours after receiving 5 Gy, 80% of the DNA was endonucleolytically cleaved. Apoptosis induction by DNA double-strand break (dsb) formation was more effective compared with induction by single-strand break (ssb) formation. After long-term culturing, LY-TH cultures became refractory to apoptosis. Apoptosis-permissive cells (LY-as, cloned from LY-TH cells) were three times more radiosensitive than clonally expanded apoptosis-refractory cells (LY-ar). Low dose-rate irradiation and maintenance at 25 o C for 5 h postirradiation was sparing in LY-ar but not LY-as cells, suggesting a repair deficiency in LY-as cells. Analysis of dsb rejoining kinetics revealed no difference in the initial phase of dsb rejoining. After 1 h, however, relative dsbs in the LY-as variant increased as endonucleolytic cleavage was initiated. Signalling for radiation-induced apoptosis in LY-as cells was independent of the DNA dsb repair pathway and appeared determined by initial events, whereas in LY-ar cells, because of an inhibition in the apoptotic pathway, survival was enhanced and modifiable by repair processes. (author)

Enhanced killing of mammalian cells by radiation combined with m-AMSA

International Nuclear Information System (INIS)

Roberts, P.B.; Millar, B.C.

1980-01-01

m-AMSA is an intercalating agent at present on Phase II trial as a chemotherapeutic drug. A 30min exposure of Chinese hamster (Line V79-753B) cells to submicromolar concentrations of m-AMSA killed 50% of the cells. The survivors had an enhanced sensitivity to radiation-induced cell killing. Depending upon the conditions, m-AMSA enhanced the radiation effect by either a decrease in the survival-curve shoulder or by an increase in slope. m-AMSA may act partly by suppressing the accumulation of sublethal damage but, if so, recovery from damage as measured in split-dose experiments with cells pretreated with the drug is not affected. m-AMSA increased radiation lethality throughout the cell cycle, but a contribution to its radiation effect from selective toxicity to cells in a radioresistant phase of the cell cycle cannot be excluded. Radiation and the drug interacted to give increased cell killing, even when the exposures to each agent were separated in time. It is concluded that m-ASMA may behave like actinomycin D and adriamycin, and enhance clinical radiation responses. In vivo testing to determine the effect of m-AMSA on the therapeutic index is recommended. (author)

Enhanced killing of mammalian cells by radiation combined with m-AMSA

Energy Technology Data Exchange (ETDEWEB)

Roberts, P B; Millar, B C [Institute of Cancer Research, Sutton (UK). Surrey Branch

1980-11-01

m-AMSA is an intercalating agent at present on Phase II trial as a chemotherapeutic drug. A 30 min exposure of Chinese hamster (Line V79-753B) cells to submicromolar concentrations of m-AMSA killed 50% of the cells. The survivors had an enhanced sensitivity to radiation-induced cell killing. Depending upon the conditions, m-AMSA enhanced the radiation effect by either a decrease in the survival-curve shoulder or by an increase in slope. m-AMSA may act partly by suppressing the accumulation of sublethal damage but, if so, recovery from damage as measured in split-dose experiments with cells pretreated with the drug is not affected. m-AMSA increased radiation lethality throughout the cell cycle, but a contribution to its radiation effect from selective toxicity to cells in a radioresistant phase of the cell cycle cannot be excluded. Radiation and the drug interacted to give increased cell killing, even when the exposures to each agent were separated in time. It is concluded that m-ASMA may behave like actinomycin D and adriamycin, and enhance clinical radiation responses. In vivo testing to determine the effect of m-AMSA on the therapeutic index is recommended.

Primary radiation damage and disturbance in cell divisions

International Nuclear Information System (INIS)

Kim, Jin Kyu; Lee, Yun-Jong; Kim, Jae-Hun; Petin, Vladislav G.; Nili, Mohammad

2008-01-01

Survived cells from a homogeneous population exposed to ionizing radiation form various colonies of different sizes and morphology on a solid nutrient medium, which appear at different time intervals after irradiation. Such a phenomenon agrees well with the modern theory of microdosimetry and classical hit-and-target models of radiobiology. According to the hit-principle, individual cells exposed to the same dose of radiation are damaged in different manners. It means that the survived cells can differ in the content of sublethal damage (hits) produced by the energy absorbed into the cell and which is not enough to give rise to effective radiation damage which is responsible for cell killing or inactivation. In diploid yeast cells, the growth rate of cells from 250 colonies of various sizes appeared at different time intervals after irradiation with 600 Gy of gamma radiation from a 60 Co isotopic source was analyzed. The survival rate after irradiation was 20%. Based on the analyses results, it was possible to categorize the clones grown from irradiated cells according to the number of sub-lesions from 1 to 4. The clones with various numbers of sub-lesions were shown to be different in their viability, radiosensitivity, sensitivity to environmental conditions, and the frequency of recombination and respiratory deficient mutations. Cells from unstable clones exhibited an enhanced radiosensitivity, and an increased portion of morphologically changed cells, nonviable cells and respiration mutants, as well. The degree of expression of the foregoing effects was higher if the number of primary sublethal lesions was greater in the originally irradiated cell. Disturbance in cell division can be characterized by cell inactivation or incorrect distribution of mitochondria between daughter cells. Thus, the suggested methodology of identification of cells with a definite number of primary sublethal lesions will promote further elucidation of the nature of primary radiation

Radiation Response in Two HPV-Infected Head-and-Neck Cancer Cell Lines in Comparison to a Non-HPV-Infected Cell Line and Relationship to Signaling Through AKT

International Nuclear Information System (INIS)

Gupta, Anjali K.; Lee, John H.; Wilke, Werner W.; Quon, Harry; Smith, Gareth; Maity, Amit; Buatti, John M.; Spitz, Douglas R.

2009-01-01

Purpose: Human papilloma virus (HPV)-associated cancers of the head and neck (H and N) are increasing in frequency and are often treated with radiation. There are conflicting data in the literature regarding the radiation response in the presence of HPV infection, with some data suggesting they may be more sensitive to radiation. There are few studies looking at in vitro effects of HPV and further sensitization by inhibitors of specific signaling pathways. We are in the process of starting a clinical trial in H and N cancer patients using nelfinavir (NFV) (which inhibits Akt) and it would be important to know the effect of HPV on radiation response ± NFV. Methods and Materials: Two naturally infected HPV-16 cell lines (UPCI-SCC90 and UMSCC47) and the HPV-negative SQ20B H and N squamous carcinoma cells were used. Western blots with or without 10 uM NFV were done to evaluate signaling from the PI3K-Akt pathway. Clonogenic assays were done in the three cell lines with or without NFV. Results: Both UPCI-SCC90 and UMSCC47 cells were sensitive to radiation as compared with SQ20B and the degree corresponded to Akt activation. The SQ20B cell line has an activating mutation in EGFR resulting in phosphorylation (P) of Akt; UMSCC47 has decreased P-phosphatase and TENsin (PTEN), resulting in increased P-Akt; UPCI-SCC90 had overexpression of P-PTEN and decreased P-Akt. NFV resulted in downregulation of Akt in all three cell lines, resulting in sensitization to radiation. Conclusions: HPV-infected H and N cancers are sensitive to radiation. The degree of sensitivity correlates to Akt activation and they can be further sensitized by NFV.

Effect of radiation on the induction of cell death in melanoma cells

International Nuclear Information System (INIS)

Notcovich, C; Delgado Gonzalez, D; Salguero, N; Bracalente, C; Molinari, B; Duran H

2012-01-01

Apoptosis is one of the desired effects of radiation during tumor treatment with radiotherapy. However, cutaneous melanoma cells are highly resistant to this kind of treatment. In order to understand the impact of radiation on melanoma cells apoptosis, the aim of this study was to characterize the radiobiological response of human melanoma cells, and to study whether a correlation between intrinsic radiosensitivity and apoptosis exists. The human melanoma cell lines A375, MELJ and SB2 were gamma-irradiated ( 137 Cs) and their radiosensitivity was evaluated through the α parameter and surviving fraction at 2 Gy (SF2) of a clonogenic assay, adjusted to the Linear-Quadratic (LQ) survival model. MELJ resulted the most radioresistant (α= 0,150±0,034 SF2= 0,71), while A375 and SB2 were the most sensitive (α=0,45±0,028 SF2=0,29 and α=0,41±0,004 SF2=0,21 respectively). Apoptotic process was evaluated at 0, 2, 6, 24 and 48 hs post irradiation at 2 and 4 Gy. Nuclear morphology was analyzed by Hoechst staining, and PARP-1 cleavage by western blot. The three cell lines nucleus with apoptotic morphology were found, being A375 and SB2 percentage of apoptotic nucleus higher than MELJ (p<0.01%). Besides, PARP-1 western blot showed for MEL-J a low presence of the cleaved forms (apoptosis indicator) compared to A375 and SB2 cell lines. Our results indicate that MELJ, the most radioresistant cell line in this study, is the less radiation induced apoptotic, demonstrating a correlation between cellular intrinsic radiosensitivity and apoptosis. Understanding melanoma radioresistance mechanism becomes extremely important in the search of new therapeutic targets that allow cell sensitization to radiotherapy (author)

Low-power millimeter wave radiations do not alter stress-sensitive gene expression of chaperone proteins.

Science.gov (United States)

Zhadobov, M; Sauleau, R; Le Coq, L; Debure, L; Thouroude, D; Michel, D; Le Dréan, Y

2007-04-01

This article reports experimental results on the influence of low-power millimeter wave (MMW) radiation at 60 GHz on a set of stress-sensitive gene expression of molecular chaperones, namely clusterin (CLU) and HSP70, in a human brain cell line. Selection of the exposure frequency is determined by its near-future applications for the new broadband civil wireless communication systems including wireless local area networks (WLAN) for domestic and professional uses. Frequencies around 60 GHz are strongly attenuated in the earth's atmosphere and such radiations represent a new environmental factor. An exposure system operating in V-band (50-75 GHz) was developed for cell exposure. U-251 MG glial cell line was sham-exposed or exposed to MMW radiation for different durations (1-33 h) and two different power densities (5.4 microW/cm(2) or 0.54 mW/cm(2)). As gene expression is a multiple-step process, we analyzed chaperone proteins induction at different levels. First, using luciferase reporter gene, we investigated potential effect of MMWs on the activation of transcription factors (TFs) and gene promoter activity. Next, using RT-PCR and Western blot assays, we verified whether MMW exposure could alter RNA accumulation, translation, or protein stability. Experimental data demonstrated the absence of significant modifications in gene transcription, mRNA, and protein amount for the considered stress-sensitive genes for the exposure durations and power densities investigated. The main results of this study suggest that low-power 60 GHz radiation does not modify stress-sensitive gene expression of chaperone proteins. (c) 2006 Wiley-Liss, Inc.

Effects of peroxide and catalase on near ultraviolet radiation sensitivity in Escherichia coli strains

Energy Technology Data Exchange (ETDEWEB)

Coombs, A.M.L.; Moss, S.H.

1987-03-01

The role of peroxide and catalase on NUV radiation sensitivity was examined in two repair competent E. coli strains, AB1157 and B/r. Exponential phase B/r is considerably more sensitive to NUV radiation than exponential phase AB1157. However, resistance to 5 mmol dm/sup -3/ H/sub 2/O/sub 2/ was induced in both AB1157 and B/r by pretreating growing cells with 30 ..mu..mol dm/sup -3/ H/sub 2/O/sub 2/. Pretreatment also induced resistance to broad-band NUV radiation in these strains. The addition of catalase to the post-irradiation plating medium increased survival to the same extent as that provided by pretreatment with 30 ..mu..mol dm/sup -3/ H/sub 2/O/sub 2/, in both strains. The NUV radiation sensitivity seen in B/r does not appear to be due to a deficiency in enzymes that scavenge H/sub 2/O/sub 2/, as a catalase deficient mutant, E. coli UM1, is more resistant to NUV radiation than B/r. Also, assays for H/sub 2/O/sub 2/ scavenging ability show little difference between AB1157 and B/r in this respect. Two hypotheses are put forward to account for the sensitivity of exponential phase B/r. Whilst it is apparent that peroxides and catalase do have a role in NUV radiation damage, it is clear that other factors also influence survival under certain conditions.

Squamous cell and basal cell carcinoma of the skin in relation to radiation therapy and potential modification of risk by sun exposure.

Science.gov (United States)

Karagas, Margaret R; Nelson, Heather H; Zens, Michael S; Linet, Martha; Stukel, Therese A; Spencer, Steve; Applebaum, Katie M; Mott, Leila; Mabuchi, Kiyohiko

2007-11-01

Epidemiologic studies consistently find enhanced risk of basal cell carcinoma of the skin among individuals exposed to ionizing radiation, but it is unclear whether the radiation effect occurs for squamous cell carcinoma. It is also not known whether subgroups of individuals are at greater risk, eg, those with radiation sensitivity or high ultraviolet radiation exposure. We analyzed data from a case-control study of keratinocyte cancers in New Hampshire. Incident cases diagnosed in 1993-1995 and 1997-2000 were identified through a state-wide skin cancer surveillance system, and controls were identified through the Department of Transportation and Center for Medicare and Medicaid Service Files (n = 1121 basal cell carcinoma cases, 854 squamous cell carcinoma cases, and 1049 controls). We found an association between history of radiation treatment and basal cell carcinoma. The association was especially strong for basal cell carcinomas arising within the radiation treatment field (odds ratio = 2.6; 95% confidence interval = 1.5-4.3), and among those treated with radiation therapy before age 20 (3.4; 1.8-6.4), those whose basal cell carcinomas occurred 40 or more years after radiation treatment (3.2; 1.8-5.8), and those treated with radiation for acne (11; 2.7-49). Similar age and time patterns of risk were observed for squamous cell carcinoma, although generally with smaller odds ratios. For basal cell carcinoma, early exposure to radiation treatment was a risk factor largely among those without a history of severe sunburns, whereas for squamous cell carcinoma, radiation treatment was a risk factor primarily among those with a sun-sensitive skin type (ie, a tendency to sunburn). Radiation treatment, particularly if experienced before age 20, seems to increase the long-term risk of both basal and squamous cell carcinomas of the skin. These risks may differ by sun exposure or host response to sunlight exposure.

Biodegradable, pH-sensitive chitosan beads obtained under microwave radiation for advanced cell culture.

Science.gov (United States)

Piątkowski, Marek; Janus, Łukasz; Radwan-Pragłowska, Julia; Bogdał, Dariusz; Matysek, Dalibor

2018-04-01

A new type of promising chitosan beads with advanced properties were obtained under microwave radiation according to Green Chemistry principles. Biomaterials were prepared using chitosan as raw material and glutamic acid/1,5-pentanodiol mixture as crosslinking agents. Additionally beads were modified with Tilia platyphyllos extract to enhance their antioxidant properties. Beads were investigated over their chemical structure by FT-IR analysis. Also their morphology has been investigated by SEM method. Additionally swelling capacity of the obtained hydrogels was determined. Lack of cytotoxicity has been confirmed by MTT assay. Proliferation studies were carried out on L929 mouse fibroblasts. Advanced properties of the obtained beads were investigated by studying pH sensitivity and antioxidant properties by DPPH method. Also susceptibility to degradation and biodegradation by Sturm Test method was evaluated. Results shows that proposed chitosan beads and their eco-friendly synthesis method can be applied in cell therapy and tissue engineering. Copyright © 2018 Elsevier B.V. All rights reserved.

Radiation-induced genetic effects in germ cells of mammals

International Nuclear Information System (INIS)

Van der Schans, G.P.

1993-01-01

The objectives of the project are a better understanding of the fundamental principles that determine the radiation sensitivity in humans, with specific attention for the role of DNA repair in germ cells. The induction and repair of damage in DNA of germ cells of the Syrian golden hamster exposed to ionizing radiation is studied at biologically relevant doses. It has also been investigated which aspects of DNA sequence or chromosomal organisation are important with respect to their influence on the repairability of DNA damage. (R.P.) 10 refs

Radiation sensitivity of fibroblast strains from patients with Usher's syndrome, Duchenne muscular dystrophy, and Huntington's disease

International Nuclear Information System (INIS)

Nove, J.; Little, J.B.; Tarone, R.E.; Robbins, J.H.

1987-01-01

The colony-forming ability of 10 normal human fibroblast cell strains and of 10 strains representing 3 degenerative diseases of either nerve or muscle cells was determined after exposure of the cells to X-rays or β-particles from tritiated water. Both methods of irradiation yielded similar comparative results. The fibroblast strains from the 5 Usher's syndrome patients and from 1 of the 2 Huntington's disease patients were hypersensitive to radiation, while those from the 3 Duchenne muscular dystrophy patients and the second Huntington's disease patient had normal sensitivity to radiation. These results indicate both disease-specific and strain-specific differences in the survival of fibroblasts after exposure to ionizing radiation. 38 refs.; 2 figs.; 3 tabs

Radiation effects on cultured mouse embryos in relation to cell division cycle

International Nuclear Information System (INIS)

Domon, M.

1982-01-01

The authors have worked with mouse embryos in vitro asking first, what are the suitable parameters to define the radiation sensitivity of embryos, and second what is a major factor determining it. The LD 50 was adopted as a parameter of the radiation sensitivity of a population in a mouse embryo system in culture. The fertilized ova were collected into Whitten's medium at various times during the pronuclear and 2-cell stages of development. They were irradiated in chambers with X-rays at doses of 0 to 800 rads. After the embryos were cultured, a set of the lethal fractions for various X-ray doses were obtained. Regarding the radiation sensitivity variation of the embryos, the LD 50 varied from 100 to 200 rads during the pronuclear stage and from 100 to 600 rads during the 2-cell stage. The embryos during the pronuclear stage were most radioresistant at early G 2 phase, followed by an increase in the sensitivity. The embryos during the 2-cell stage were also most radioresistant at early G 2 phase and were more sensitive when they got close to either the first or the second cleavage division. Furthermore, it seems that the factor 6 of the large variation was due to the extremely long G 2 period, 14 hrs for the 2-cell embryos. That is, the pooled 2-cell embryos were in a relative sense well synchronized with G 2 phase. In contrast, the synchrony was poor during the pronuclear stage, which led to less variation of the LD 50 for the pronuclear embryos. It is concluded that during the early cleavage stages of mice, radiosensitivity is mainly governed by the content of cells of various cell cycle ages in the embryo. (Namekawa, K.)

Fabrication and characterization of UV-emitting nanoparticles as novel radiation sensitizers targeting hypoxic tumor cells

Science.gov (United States)

Squillante, Michael R.; Jüstel, Thomas; Anderson, R. Rox; Brecher, Charles; Chartier, Daniel; Christian, James F.; Cicchetti, Nicholas; Espinoza, Sara; McAdams, Daniel R.; Müller, Matthias; Tornifoglio, Brooke; Wang, Yimin; Purschke, Martin

2018-06-01

Radiation therapy is one of the primary therapeutic techniques for treating cancer, administered to nearly two-thirds of all cancer patients. Although largely effective in killing cancer cells, radiation therapy, like other forms of cancer treatment, has difficulty dealing with hypoxic regions within solid tumors. The incomplete killing of cancer cells can lead to recurrence and relapse. The research presented here is investigating the enhancement of the efficacy of radiation therapy by using scintillating nanoparticles that emit UV photons. UV photons, with wavelengths between 230 nm and 280 nm, are able to inactivate cells due to their direct interaction with DNA, causing a variety of forms of damage. UV-emitting nanoparticles will enhance the treatment in two ways: first by generating UV photons in the immediate vicinity of cancer cells, leading to direct and oxygen-independent DNA damage, and second by down-converting the applied higher energy X-rays into softer X-rays and particles that are more efficiently absorbed in the targeted tumor region. The end result will be nanoparticles with a higher efficacy in the treatment of hypoxic cells in the tumor, filling an important, unmet clinical need. Our preliminary experiments show an increase in cell death using scintillating LuPO4:Pr nanoparticles over that achieved by the primary radiation alone. This work describes the fabrication of the nanoparticles, their physical characterization, and the spectroscopic characterization of the UV emission. The work also presents in vitro results that demonstrate an enhanced efficacy of cell killing with x-rays and a low unspecific toxicity of the nanoparticles.

Effect of antisense c-raf-1 on tumorigenicity and radiation sensitivity of a human squamous carcinoma

International Nuclear Information System (INIS)

Kasid, U.; Pfeifer, A.; Brennan, T.; Beckett, M.; Weichselbaum, R.R.; Dritschilo, A.; Mark, G.E.

1989-01-01

Antisense RNA-mediated inhibition of gene expression was used to investigate the biological function of the c-raf-1 gene in a radiation-resistant human squamous carcinoma cell line, SQ-20B. S1 nuclease protection assays revealed that transfection of full-length raf complementary DNA in the antisense orientation (AS) leads to a specific reduction (greater than tenfold) of steady-state levels of the endogenous c-raf-1 sense (S) transcript in SQ-20B cells. In nude mice, the malignant potential of SQ-20B cells transfected with raf (S) was significantly increased relative to that of SQ-20B cells transfected with raf (AS). SQ-20B cells containing transfected raf (S) maintained a radiation-resistant phenotype as compared to those cells harboring the AS version, which appeared to have enhanced radiation sensitivity. These data indicate that the reduced expression of endogenous c-raf-1 is sufficient to modulate the tumorigenicity and the radiation-resistant phenotype of SQ-20B cells, thus implicating c-raf-1 in a pathway important to the genesis of this type of cancer

Enhancement of radiation effect on cancer cells by gold-pHLIP

Science.gov (United States)

Antosh, Michael P.; Wijesinghe, Dayanjali D.; Shrestha, Samana; Lanou, Robert; Huang, Yun Hu; Hasselbacher, Thomas; Fox, David; Neretti, Nicola; Sun, Shouheng; Katenka, Natallia; Cooper, Leon N; Andreev, Oleg A.; Reshetnyak, Yana K.

2015-01-01

Previous research has shown that gold nanoparticles can increase the effectiveness of radiation on cancer cells. Improved radiation effectiveness would allow lower radiation doses given to patients, reducing adverse effects; alternatively, it would provide more cancer killing at current radiation doses. Damage from radiation and gold nanoparticles depends in part on the Auger effect, which is very localized; thus, it is important to place the gold nanoparticles on or in the cancer cells. In this work, we use the pH-sensitive, tumor-targeting agent, pH Low-Insertion Peptide (pHLIP), to tether 1.4-nm gold nanoparticles to cancer cells. We find that the conjugation of pHLIP to gold nanoparticles increases gold uptake in cells compared with gold nanoparticles without pHLIP, with the nanoparticles distributed mostly on the cellular membranes. We further find that gold nanoparticles conjugated to pHLIP produce a statistically significant decrease in cell survival with radiation compared with cells without gold nanoparticles and cells with gold alone. In the context of our previous findings demonstrating efficient pHLIP-mediated delivery of gold nanoparticles to tumors, the obtained results serve as a foundation for further preclinical evaluation of dose enhancement. PMID:25870296

Effect of growth temperature on lipid composition and ultraviolet sensitivity of human cells

International Nuclear Information System (INIS)

McAleer, M.A.; Moore, S.P.; Moss, S.H.

1987-01-01

Human skin fibroblasts were incubated at either 25 or 37 0 C before UV irradiation. Cells incubated at 25 0 C were more resistant to near UV radiation than cells grown at 37 0 C, but cells grown at the lower temperature were more sensitive to 254 nm radiation. Fatty acid analysis of membranes of cells showed that cells incubated at the lower temperature contained significantly higher amounts of linoleic acid (18:2) and linolenic acid (18:3) than cells incubated at 37 0 C. To determine if this difference in fatty acid content of the membranes was responsible for the UV survival characteristics of cells incubated at different temperatures, cells were enriched with either linoleate or linolenate during a 37 0 C incubation period. Gas chromatography revealed that cells incorporated the supplied fatty acid. Fatty acid enriched cells were then irradiated with near UV, and survival characteristics were compared to those obtained with cells grown at the lower incubation temperature. The results suggest that the different proportion of fatty acid content of the cells is not the cause of different UV sensitivities of cells grown at 25 0 C compared to cells grown at 37 0 C. (author)

Overexpression of metallothionein in CHO cells and its effect on cell killing by ionizing radiation and alkylating agents

International Nuclear Information System (INIS)

Lohrer, H.; Robson, T.

1989-01-01

Metallothionein protein protects cells from the toxic effects of heavy metal ions. To establish its protective function against ionizing radiation and alkylating agents, a model system was created by transfecting two CHO cell lines (wild-type, K1-2 and X-ray sensitive, xrs-2 subclone Bc11) with the human metallothionein II-A (hMTII-A) gene integrated in a bovine papilloma derived autonomously replicating vector. The isolated transfectants are cadmium-resistant (Cd 1 ), due to the overexpression of the hMTII-A gene. Their steady-state level of hMTII-A mRNA can be increased up to 40-fold after Cd treatment and 20-fold after induction with ionizing radiation. The transfected cell lines proved to be as sensitive as the recipient cell lines to ionizing radiation and bleomycin but the transfectants were significantly more resistant to N-methyl-nitro-nitrosoguanidine (MNNG) and mitomycin C (MMC). These results lead to the conclusion that the MT protein does provide a defence mechanism to protect cells from monofunctional alkylating and cross-linking agents but not from free radicals. (author)

Overexpression of metallothionein in CHO cells and its effect on cell killing by ionizing radiation and alkylating agents

Energy Technology Data Exchange (ETDEWEB)

Lohrer, H.; Robson, T. (Newcastle upon Tyne Univ. (UK). Cancer Research Unit)

1989-12-01

Metallothionein protein protects cells from the toxic effects of heavy metal ions. To establish its protective function against ionizing radiation and alkylating agents, a model system was created by transfecting two CHO cell lines (wild-type, K1-2 and X-ray sensitive, xrs-2 subclone Bc11) with the human metallothionein II-A (hMTII-A) gene integrated in a bovine papilloma derived autonomously replicating vector. The isolated transfectants are cadmium-resistant (Cd{sup 1}), due to the overexpression of the hMTII-A gene. Their steady-state level of hMTII-A mRNA can be increased up to 40-fold after Cd treatment and 20-fold after induction with ionizing radiation. The transfected cell lines proved to be as sensitive as the recipient cell lines to ionizing radiation and bleomycin but the transfectants were significantly more resistant to N-methyl-nitro-nitrosoguanidine (MNNG) and mitomycin C (MMC). These results lead to the conclusion that the MT protein does provide a defence mechanism to protect cells from monofunctional alkylating and cross-linking agents but not from free radicals. (author).

Effect of nitric oxide and hydrogen sulfide on radiation sensitivity of spores of Bacillus megaterium in suspension

Energy Technology Data Exchange (ETDEWEB)

Russell, C

1966-01-01

The effect of nitric oxide on the sensitivity to radiation of spores of B. megaterium in water suspension is similar to that seen in vegetative cells of E. coli. The spores are less sensitive in the presence of hydrogen sulfide. 11 references, 1 figure.

The effect of dexamethasone on the radiation survival response and misonidazole-induced hypoxic-cell cytotoxicity in Chinese hamster cells V-79-753B in vitro

International Nuclear Information System (INIS)

Millar, B.C.; Jinks, S.

1981-01-01

Overnight exposure of Chinese hamster cells, V-79-753B, to microgram quantities of the synthetic corticosteroid, dexamethasone, resulted in a decrease in sensitivity towards radiation, both in air and in hypoxia. The effect was dose-modifying and the oxygen enhancement ratio did not change appreciably. Similarly, when dexamethasone-treated hypoxic cells were irradiated in the presence of misonidazole, a hypoxic cell radiosensitizer, there was a decrease in radiation sensitivity compared with untreated hypoxic cells irradiated with misonidazole. (author)

Regulation of early and delayed radiation responses in rat small intestine by capsaicin-sensitive nerves

International Nuclear Information System (INIS)

Wang Junru; Zheng Huaien; Kulkarni, Ashwini; Ou Xuemei; Hauer-Jensen, Martin

2006-01-01

Purpose: Mast cells protect against the early manifestations of intestinal radiation toxicity, but promote chronic intestinal wall fibrosis. Intestinal sensory nerves are closely associated with mast cells, both anatomically and functionally, and serve an important role in the regulation of mucosal homeostasis. This study examined the effect of sensory nerve ablation on the intestinal radiation response in an established rat model. Methods and Materials: Rats underwent sensory nerve ablation with capsaicin or sham ablation. Two weeks later, a localized segment of ileum was X-irradiated or sham irradiated. Structural, cellular, and molecular changes were examined 2 weeks (early injury) and 26 weeks (chronic injury) after irradiation. The mast cell dependence of the effect of sensory nerve ablation on intestinal radiation injury was assessed using c-kit mutant (Ws/Ws) mast cell-deficient rats. Results: Capsaicin treatment caused a baseline reduction in mucosal mast cell density, crypt cell proliferation, and expression of substance P and calcitonin gene-related peptide, two neuropeptides released by sensory neurons. Sensory nerve ablation strikingly exacerbated early intestinal radiation toxicity (loss of mucosal surface area, inflammation, intestinal wall thickening), but attenuated the development of chronic intestinal radiation fibrosis (collagen I accumulation and transforming growth factor β immunoreactivity). In mast cell-deficient rats, capsaicin treatment exacerbated postradiation epithelial injury (loss of mucosal surface area), but none of the other aspects of radiation injury were affected by capsaicin treatment. Conclusions: Ablation of capsaicin-sensitive enteric neurons exacerbates early intestinal radiation toxicity, but attenuates development of chronic fibroproliferative changes. The effect of capsaicin treatment on the intestinal radiation response is partly mast cell dependent

Sensitivity of planktonic and biofilm-associated Aeromonas spp. to ionizing radiation

International Nuclear Information System (INIS)

Nagar, Vandan; Bandekar, J.R.

2015-01-01

Aeromonas cells, on radiation sensitivity is isolate specific. (author)

Radiation effects on cell membranes

International Nuclear Information System (INIS)

Koeteles, G.J.

1982-01-01

The recent developments in the field of membrane biology of eukaryotic cells result in revival of relevant radiobiological studies. The spatial relations and chemical nature of membrane components provide rather sensitive targets. Experimental data are presented concerning the effects of relatively low doses of X-irradiation and low concentration of tritiated water (HTO) on various receptor functions - concanavalin A, cationized ferritin, poliovirus - of plasma membranes of animal and human cells which point to early and temporary disturbances of the composite structures and functions of membranes. References are given to the multifold roles of radiationinduced membrane phenomena on the development and regeneration of radiation injuries. (orig.)

Radiation effects on cell membranes

Energy Technology Data Exchange (ETDEWEB)

Koeteles, G.J.

1982-11-01

The recent developments in the field of membrane biology of eukaryotic cells result in revival of relevant radiobiological studies. The spatial relations and chemical nature of membrane components provide rather sensitive targets. Experimental data are presented concerning the effects of relatively low doses of X-irradiation and low concentration of tritiated water (HTO) on various receptor functions - concanavalin A, cationized ferritin, poliovirus - of plasma membranes of animal and human cells which point to early and temporary disturbances of the composite structures and functions of membranes. References are given to the multifold roles of radiationinduced membrane phenomena on the development and regeneration of radiation injuries.

DNA Damage by Radiation in Tradescantia Leaf Cells

International Nuclear Information System (INIS)

Han, Min; Hyun, Kyung Man; Ryu, Tae Ho; Kim, Jin Kyu; Nili, Mohammad

2010-01-01

The comet assay is currently used in different areas of biological sciences to detect DNA damage. The comet assay, due to its simplicity, sensitivity and need of a few cells, is ideal as a short-term genotoxicity test. The comet assay can theoretically be applied to every type of eukaryotic cell, including plant cells. Plants are very useful as monitors of genetic effects caused by pollution in the atmosphere, water and soil. Tradescantia tests are very useful tools for screening the mutagenic potential in the environment. Experiments were conducted to study the genotoxic effects of ionizing radiations on the genome integrity, particularly of Tradescantia. The increasingly frequent use of Tradescantia as a sensitive environmental bioindicator of genotoxic effects. This study was designed to assess the genotoxicity of ionizing radiation using Tradescnatia-comet assay. The development of comet assay has enabled investigators to detect DNA damage at the levels of cells. To adapt this assay to plant cells, nuclei were directly obtained from Tradescantia leaf samples. A significant dose-dependent increase in the average tail moment values over the negative control was observed. Recently the adaptation of this technique to plant cells opens new possibilities for studies in variety area. The future applications of the comet assay could impact some other important areas, certainly, one of the limiting factors to its utility is the imagination of the investigator.

DNA Damage by Radiation in Tradescantia Leaf Cells

Energy Technology Data Exchange (ETDEWEB)

Han, Min; Hyun, Kyung Man; Ryu, Tae Ho; Kim, Jin Kyu [Korea Atomic Energy Research Institute, Advanced Radiation Technology Institute, Jeongeup (Korea, Republic of); Nili, Mohammad [Dawnesh Radiation Research Institute, Barcelona (Spain)

2010-04-15

The comet assay is currently used in different areas of biological sciences to detect DNA damage. The comet assay, due to its simplicity, sensitivity and need of a few cells, is ideal as a short-term genotoxicity test. The comet assay can theoretically be applied to every type of eukaryotic cell, including plant cells. Plants are very useful as monitors of genetic effects caused by pollution in the atmosphere, water and soil. Tradescantia tests are very useful tools for screening the mutagenic potential in the environment. Experiments were conducted to study the genotoxic effects of ionizing radiations on the genome integrity, particularly of Tradescantia. The increasingly frequent use of Tradescantia as a sensitive environmental bioindicator of genotoxic effects. This study was designed to assess the genotoxicity of ionizing radiation using Tradescnatia-comet assay. The development of comet assay has enabled investigators to detect DNA damage at the levels of cells. To adapt this assay to plant cells, nuclei were directly obtained from Tradescantia leaf samples. A significant dose-dependent increase in the average tail moment values over the negative control was observed. Recently the adaptation of this technique to plant cells opens new possibilities for studies in variety area. The future applications of the comet assay could impact some other important areas, certainly, one of the limiting factors to its utility is the imagination of the investigator.

Combined radiation-protective and radiation-sensitizing agents. III. Radiosensitization by misonidazole as a function of concentrations of endogenous glutathione or exogenous thiols

International Nuclear Information System (INIS)

Koch, C.J.; Stobbe, C.C.; Baer, K.A.

1986-01-01

Radiosensitization of V79 Chinese hamster fibroblasts by 0.5 mM misonidazole is a smooth function of endogenous glutathione (GSH) levels as modulated upwards by pre-incubation in medium containing cysteamine, or downwards by pre-incubation in medium containing buthionine sulfoximine. The enhancement ratio (radiation sensitivity in nitrogen/radiation sensitivity in nitrogen +/- sensitizer or thiol) varies from 1.3 at 12 mM to 2.25 at less than 0.1 mM endogenous GSH. The enhanced radiosensitivity of thiol-depleted hypoxic cells is reversed when exogenous thiols are added, and for equivalent ER, the exogenous thiol concentrations are much lower than the endogenous GSH concentrations. Measurement of intracellular drug concentrations amplified rather than diminished the above discrepancy, since intracellular concentrations of cysteamine were lower and glutathione much lower than the extracellular concentrations. Three possible explanations are addressed: an external membrane component of damage is involved, long-range protection to DNA target radicals is possible from outside the cell (e.g., donation of electrons), and (c) endogenous glutathione is not in a free or exchangeable state (e.g., bound)

The radiation hypersensitivity of cells at mitosis.

Science.gov (United States)

Stobbe, C C; Park, S J; Chapman, J D

2002-12-01

Mitotic cells are hypersensitive to ionizing radiation, exhibiting single-hit inactivation coefficients near to those of repair deficient cell lines and lymphocytes. To elucidate possible mechanisms for this hypersensitivity, the kinetics of oxygen radiosensitization, the proportion of indirect effect by OH radicals and the kinetics of radiation-induced DNA strand breakage in the chromatin of mitotic cells were investigated. Synchronized populations of >90% mitotic HT-29 cells were obtained by the mitotic shake-off method. Cells were irradiated at indirect effect of OH radicals was investigated with the radical scavenger, DMSO. DNA strand breakage was measured by the comet assay. Mitotic HT-29 cell inactivation is well described by a single-hit inactivation coefficient (alpha) of 1.14 +/- 0.06 Gy(-1). The oxygen enhancement ratio of mitotic cells (at 10% survival) was found to be approximately 2.0, significantly lower than the value of 2.8 measured for interphase (asynchronous) cells. More than 60% of mitotic cell killing was eliminated when the media contained 2 M DMSO, indicating that indirect effect is as important in the killing of mitotic cells as it is for interphase cells. The chromatin in mitotic cells was found to be ~2.8 times more sensitive to radiation-induced DNA single-strand breakage than the chromatin of interphase cells. The alpha-inactivation coefficient of mitotic HT-29 cells was ~30 times larger than that of interphase cells. Mitotic cell chromatin appears to contain intrinsic DNA breaks that are not lethal. In addition, chromatin in mitotic cells was found to be more susceptible to radiation-induced DNA strand-breakage than the dispersed chromatin of interphase cells. How the enhanced production of these simple DNA lesions (that are usually reparable) translates into the lethal (non-reparable) events associated with alpha-inactivation is not known. The compaction/dispersion status of DNA throughout the cell cycle appears to be an important

Recent Advances in Dye Sensitized Solar Cells

Directory of Open Access Journals (Sweden)

Umer Mehmood

2014-01-01

Full Text Available Solar energy is an abundant and accessible source of renewable energy available on earth, and many types of photovoltaic (PV devices like organic, inorganic, and hybrid cells have been developed to harness the energy. PV cells directly convert solar radiation into electricity without affecting the environment. Although silicon based solar cells (inorganic cells are widely used because of their high efficiency, they are rigid and manufacturing costs are high. Researchers have focused on organic solar cells to overcome these disadvantages. DSSCs comprise a sensitized semiconductor (photoelectrode and a catalytic electrode (counter electrode with an electrolyte sandwiched between them and their efficiency depends on many factors. The maximum electrical conversion efficiency of DSSCs attained so far is 11.1%, which is still low for commercial applications. This review examines the working principle, factors affecting the efficiency, and key challenges facing DSSCs.

Sensitivities in synchrotron radiation TXRF

International Nuclear Information System (INIS)

Pianetta, P.; Baur, K.; Brennan, S.

2000-01-01

This work describes the progress we achieved at the Stanford Synchrotron Radiation Laboratory (SSRL) in improving the sensitivity for both the transition metals and light elements such as Al and Na. The transition metal work has matured to the point where a facility exists at SSRL in which semiconductor companies are able to perform industrially relevant measurements at state of the art detection limits. This facility features clean wafer handling and automated data acquisition making routine analytical measurements possible. The best sensitivity demonstrated so far is 3.4 E7 atoms/cm 2 for a 5000 second count time corresponding to 7.6 E7 atoms/cm 2 for a standard 1000 second count time. This is more than a factor of 100 better than what can be achieved with conventional TXRF systems. The detection of light elements such as Al and Na is challenging due to the presence of the h stronger Si fluorescence peak. For traditional energy-dispersive detection only the tunability of synchrotron radiation to excitation energies below the Si-K absorption edge leads to an acceptable sensitivity for Al detection which is limited by a large background due to inelastic x-ray Raman scattering. An alternative approach to overcome the Raman contribution and the strong Si fluorescence is to use a wavelength-dispersive spectrometer for fluorescence detection. The benefits of such a multilayer spectrometer over a solid state detector are its higher energy resolution and greater dynamic range. This strategy allows primary excitation above the Si K absorption edge, eliminating the background due to Raman scattering, and a gracing emission geometry to guarantee high surface sensitivity. Studies testing this concept in combination with high flux synchrotron radiation are underway and first results will be presented. (author)

Curcumin induces chemo/radio-sensitization in ovarian cancer cells and curcumin nanoparticles inhibit ovarian cancer cell growth

Directory of Open Access Journals (Sweden)

Yallapu Murali M

2010-04-01

Full Text Available Abstract Background Chemo/radio-resistance is a major obstacle in treating advanced ovarian cancer. The efficacy of current treatments may be improved by increasing the sensitivity of cancer cells to chemo/radiation therapies. Curcumin is a naturally occurring compound with anti-cancer activity in multiple cancers; however, its chemo/radio-sensitizing potential is not well studied in ovarian cancer. Herein, we demonstrate the effectiveness of a curcumin pre-treatment strategy for chemo/radio-sensitizing cisplatin resistant ovarian cancer cells. To improve the efficacy and specificity of curcumin induced chemo/radio sensitization, we developed a curcumin nanoparticle formulation conjugated with a monoclonal antibody specific for cancer cells. Methods Cisplatin resistant A2780CP ovarian cancer cells were pre-treated with curcumin followed by exposure to cisplatin or radiation and the effect on cell growth was determined by MTS and colony formation assays. The effect of curcumin pre-treatment on the expression of apoptosis related proteins and β-catenin was determined by Western blotting or Flow Cytometry. A luciferase reporter assay was used to determine the effect of curcumin on β-catenin transcription activity. The poly(lactic acid-co-glycolic acid (PLGA nanoparticle formulation of curcumin (Nano-CUR was developed by a modified nano-precipitation method and physico-chemical characterization was performed by transmission electron microscopy and dynamic light scattering methods. Results Curcumin pre-treatment considerably reduced the dose of cisplatin and radiation required to inhibit the growth of cisplatin resistant ovarian cancer cells. During the 6 hr pre-treatment, curcumin down regulated the expression of Bcl-XL and Mcl-1 pro-survival proteins. Curcumin pre-treatment followed by exposure to low doses of cisplatin increased apoptosis as indicated by annexin V staining and cleavage of caspase 9 and PARP. Additionally, curcumin pre

Combined effects of hyperthermia and radiation in cultured mammalian cells

International Nuclear Information System (INIS)

Ben-Hur, E.; Elkind, M.M.; Riklis, E.

1977-01-01

Hyperthermia (temperatures of 39 0 C or higher) enhances the killing of mammalian cells by ionizing radiation (fission-spectrum neutrons and x-rays). The nature and the magnitude of the enhanced radiation killing varies with temperature and for a fixed temperature during irradiation, the enhanced lethality varies inversely with dose rate. For temperatures up to 41 0 C, dose fractionation measurements indicate that hyperthermia inhibits the repair of sublethal damage. At higher temperatures, the expression of potentially lethal damage is enhanced. Since the effect of heat is greatest in cells irradiated during DNA synthesis, the radiation age-response pattern is flattened by hyperthermia. In addition to the enhanced cell killing described above, three other features of the effect of hyperthermia are important in connection with the radiation treatment of cancer. The first is that heat selectively sensitizes S-phase cells to radiation. The second is that it takes radiation survivors 10 to 20 hrs after a modest heat treatment to recover their ability to repair sublethal damage. And the third is that hyperthermia reduces the magnitude of the oxygen enhancement ratio. Thus, heat if applied selectively, could significantly increase the margin of damage between tumors and normal tissues

Interaction of nitroimidazole sensitizers and oxygen in the radiosensitization of mammalian cells at ultrahigh dose rates

International Nuclear Information System (INIS)

Michaels, H.B.; Ling, C.C.; Epp, E.R.; Peterson, E.C.

1981-01-01

When CHO cells, equilibrated with 0.44% oxygen, are irradiated with single 3-nsec pulses of electrons from a 600-kV-field emission source, a breaking survival curve is observed. The breaking behavior, believed to be the result of radiolytic oxygen depletion, can be prevented by the presence of a relatively low concentration of the hypoxic cell sensitizer misonidazole; similar results are obtained with metronidazole and Ro-05-9963. The resulting survival curves exhibit a sensitized response similar to that obtained with conventional dose rate radiation for CHO cells under this oxygen concentration. This degree of sensitization is greater than that observed for CHO cells irradiated at ultrahigh dose rates under the same concentration of sensitizer in nitrogen. The data suggest that the nitroimidazole compounds interfere with the radiation chemical oxygen depletion process and that the radiosensitization observed in the nonbreaking survival curve is the consequence of sensitization by both the nitroimidazole and, primarily, the oxygen rather than a direct subsitution for oxygen by the sensitizer. This conclusion is also supported by data obtained in double-pulse experiments. The results are discussed with regard to the mechanisms of the oxygen depletion process and radiosensitization

Correlation of radiation sensitivity and nitrofurantoin sensitivity of Escherichia coli K-12

International Nuclear Information System (INIS)

Kloeck, K.

1981-01-01

The Uvr- and rec-mutants of E.coli K-12 have been tested with a view to their radiation- and nitrofuration sensitivity. The tests showed that all mutants tested were more radiation- and NF-sensitive than the wild type AB 1157. When the NF-sensitivity had been compared to the UV- and X-ray sensitivity it became obvious that the NF-sensitivity is correlated to the UV-sensitivity. Studies carried out with regard to the time dependence of the NF-effect on E.coli showed that the effect of NF on E. Coli became weaker after about 1 1/2 to 2 hours. That is possibly caused by the fact that the E. coli bacteria succeed in reducing the NF to an inactive form. By means of nitrosoguanidine mutants of E-coli AB 1157 had been induced and by means of the Replicite Plating Method, NF-sensible mutants had been isolated from the plutonium mixture. Among the mutants which had been isolated by this method, 74% had been more UV-sensitive than the wild type and 55% more X-ray sensitive. Thus NF-sensitive mutants have not necessarily to be considered as rec-mutants as there are also uvr-mutants in the mixture. (orig.) [de

Radiation-induced changes in nucleoid halo diameteres of aerobic and hypoxic SF-126 human brain tumor cells

International Nuclear Information System (INIS)

Wang, J.; Basu, H.S.; Hu, L.; Feuerstein, B.G.; Deen, D.F.

1995-01-01

Nucleoid halo diameters were measured to assay changes in DNA supercoiling in human brain tumor cell line SF-126 after irradiation under aerobic or hypoxic conditions. In unirradiated aerobic cells, a typical propidium iodide titration curve showed that with increasing concentrations of propodium iodide, the halo diameter increased and then decreased with the unwinding and subsequent rewinding of DNA supercoils. In irradiated cells, the rewinding of DNA supercoils was inhibited, resulting in an increased halo diameter, in a radiation dose-dependent manner. To produce equal increases in halo diameter required about a threefold higher radiation dose in hypoxic cells than in aerobic cells. Quantitatively similiar differences in the radiation sensitivities of hypoxic and aerobic cells were demonstrated by a colony-forming efficiency assay. These findings suggest that the nucleoid halo assay may be used as a rapid measure of the inherent radiation sensitivity of human tumors. 22 refs., 5 figs

Roadmap to Clinical Use of Gold Nanoparticles for Radiation Sensitization

Energy Technology Data Exchange (ETDEWEB)

Schuemann, Jan, E-mail: jschuemann@mgh.harvard.edu [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (United States); Berbeco, Ross [Department of Radiation Oncology, Brigham and Women' s Hospital, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts (United States); Chithrani, Devika B. [Department of Physics, Ryerson University, Toronto, Ontario (Canada); Cho, Sang Hyun [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Kumar, Rajiv [Nanomedicine Science and Technology Center, Northeastern University, Boston, Massachusetts (United States); Department of Radiation Oncology, Harvard Medical School, Boston, Massachusetts (United States); McMahon, Stephen J. [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts (United States); Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom); Sridhar, Srinivas [Nanomedicine Science and Technology Center, Northeastern University, Boston, Massachusetts (United States); Department of Radiation Oncology, Harvard Medical School, Boston, Massachusetts (United States); Krishnan, Sunil [Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)

2016-01-01

The past decade has seen a dramatic increase in interest in the use of gold nanoparticles (GNPs) as radiation sensitizers for radiation therapy. This interest was initially driven by their strong absorption of ionizing radiation and the resulting ability to increase dose deposited within target volumes even at relatively low concentrations. These early observations are supported by extensive experimental validation, showing GNPs' efficacy at sensitizing tumors in both in vitro and in vivo systems to a range of types of ionizing radiation, including kilovoltage and megavoltage X rays as well as charged particles. Despite this experimental validation, there has been limited translation of GNP-mediated radiation sensitization to a clinical setting. One of the key challenges in this area is the wide range of experimental systems that have been investigated, spanning a range of particle sizes, shapes, and preparations. As a result, mechanisms of uptake and radiation sensitization have remained difficult to clearly identify. This has proven a significant impediment to the identification of optimal GNP formulations which strike a balance among their radiation sensitizing properties, their specificity to the tumors, their biocompatibility, and their imageability in vivo. This white paper reviews the current state of knowledge in each of the areas concerning the use of GNPs as radiosensitizers, and outlines the steps which will be required to advance GNP-enhanced radiation therapy from their current pre-clinical setting to clinical trials and eventual routine usage.

The sensitivity of an actinic reticuloid cell strain to near-ultraviolet radiation and its modification by Trolox-C, a vitamin E analogue

International Nuclear Information System (INIS)

Kralli, A.; Moss, S.H.

1987-01-01

Near-UV radiation (365 nm)-induced lethality, as measured by colony-forming ability, showed an actinic reticuloid cell strain to be sensitive relative to normal human fibroblasts, when irradiated at 25 0 C. This effect was not seen after far-UV (254 nm) irradiation. Trolox-C, a water-soluble analogue of vitamin E, incorporated in the pre-irradiation growth medium or in the post-irradiation plating medium, protected the actinic reticuloid cells to the extent that they were as resistant as normal cells. Plating medium containing Trolox-C did not provide differential protection against inactivation of the two cell strains by wavelengths in the far-UV region. The protection provided by Trolox-C, an analogue of the natural antioxidant vitamin E, suggests some free radical involvement in the aetiology of the disease. (author)

VARIATIONS IN RADIATION SENSITIVITY AND REPAIR AMONG DIFFERENT HEMATOPOIETIC STEM-CELL SUBSETS FOLLOWING FRACTIONATED-IRRADIATION

NARCIS (Netherlands)

DOWN, JD; BOUDEWIJN, A; VANOS, R; THAMES, HD; PLOEMACHER, RE

1995-01-01

The radiation dose-survival of various hematopoietic cell subsets in murine bone marrow (BM) was determined in the cobblestone area forming cell (CAFC) assay under conditions of single-, split-, and multiple-dose irradiation. A greater recovery in cell survival with decreasing dose per fraction, or

Characterization of glioma stem cells through multiple stem cell markers and their specific sensitization to double-strand break-inducing agents by pharmacological inhibition of ataxia telangiectasia mutated protein.

Science.gov (United States)

Raso, Alessandro; Vecchio, Donatella; Cappelli, Enrico; Ropolo, Monica; Poggi, Alessandro; Nozza, Paolo; Biassoni, Roberto; Mascelli, Samantha; Capra, Valeria; Kalfas, Fotios; Severi, Paolo; Frosina, Guido

2012-09-01

Previous studies have shown that tumor-driving glioma stem cells (GSC) may promote radio-resistance by constitutive activation of the DNA damage response started by the ataxia telangiectasia mutated (ATM) protein. We have investigated whether GSC may be specifically sensitized to ionizing radiation by inhibiting the DNA damage response. Two grade IV glioma cell lines (BORRU and DR177) were characterized for a number of immunocytochemical, karyotypic, proliferative and differentiative parameters. In particular, the expression of a panel of nine stem cell markers was quantified by reverse transcription-polymerase chain reaction (RT-PCR) and flow cytometry. Overall, BORRU and DR177 displayed pronounced and poor stem phenotypes, respectively. In order to improve the therapeutic efficacy of radiation on GSC, the cells were preincubated with a nontoxic concentration of the ATM inhibitors KU-55933 and KU-60019 and then irradiated. BORRU cells were sensitized to radiation and radio-mimetic chemicals by ATM inhibitors whereas DR177 were protected under the same conditions. No sensitization was observed after cell differentiation or to drugs unable to induce double-strand breaks (DSB), indicating that ATM inhibitors specifically sensitize glioma cells possessing stem phenotype to DSB-inducing agents. In conclusion, pharmacological inhibition of ATM may specifically sensitize GSC to DSB-inducing agents while sparing nonstem cells. © 2012 The Authors; Brain Pathology © 2012 International Society of Neuropathology.

Do intracellular thiol or peroxidase levels block radiation sensitization by nitrous oxide in some E. coli strains?

International Nuclear Information System (INIS)

Ewing, D.; Guilfoil, D.S.; Ohm, M.B.

1991-01-01

Although nitrous oxide (N 2 O) is often a radiation sensitizer in procaryotic cells, it fails to sensitize some strains of bacteria, some yeast strains, and most eucaryotic cell lines. At present this inconsistency cannot be satisfactorily explained. The experiments here use eight strains of E. coli, some of which are not sensitized by N 2 O, to test the hypotheses that N 2 O's failure to sensitize might be based on high thiol content or on low peroxidase activity. Our data contradict those hypotheses. In addition, further data show that the strains not sensitized by N 2 O contain no unique cellular component or compound which blocks damage from N 2 O. (author)

Relative radiation sensitivity of insulators, stabilizers, and superconductors

International Nuclear Information System (INIS)

Van Konynenburg, R.A.; Guinan, M.W.

1980-12-01

The operating conditions of the magnets including temperature and radiation fields are discussed. Comments were made on the nuclear heating. Components of the magnet system, including the materials used, the important properties, the atomic structure, the damage mechanism, and the effects of room temperature warmup are described. Some failure criteria for the various components are suggested. Available data concerning radiation effects on each component are discussed. Their radiation sensitivities are compared using the conditions calculated for the ETF toroidal field magnet inboard leg, and ranked in order of sensitivity. Comments were made on the implications of this ranking for the directions of future applied materials research

Mesenchymal stem cells are sensitive to treatment with kinase inhibitors and ionizing radiation

Energy Technology Data Exchange (ETDEWEB)

Nicolay, Nils H.; Debus, Juergen; Huber, Peter E. [Heidelberg University Hospital, Department of Radiation Oncology, Heidelberg (Germany); German Cancer Research Center (dkfz), Department of Molecular and Radiation Oncology, Heidelberg (Germany); Sommer, Eva; Lopez Perez, Ramon; Wirkner, Ute [German Cancer Research Center (dkfz), Department of Molecular and Radiation Oncology, Heidelberg (Germany); Bostel, Tilman [Heidelberg University Hospital, Department of Radiation Oncology, Heidelberg (Germany); Ho, Anthony D.; Saffrich, Rainer [Heidelberg University Hospital, Department of Hematology, Oncology and Rheumatology, Heidelberg (Germany); Lahn, Michael [Lilly Research Laboratories, Oncology Early Clinical Investigation, Indianapolis, IN (United States)

2014-11-15

Mesenchymal stem cells (MSCs) can regenerate damaged tissues and may therefore be of importance for normal tissue repair after cancer treatment. Small molecule receptor kinase inhibitors (RKIs) have recently been introduced into cancer treatment. However, the influence of these drugs - particularly in combination with radiotherapy - on the survival of MSCs is largely unknown. The sensitivity of human primary MSCs from healthy volunteers and primary human fibroblast cells to small molecule kinase inhibitors of the vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF) and transforming growth factor β (TGFβ) receptors, as well to inhibitors of c-Kit, was examined in combination with ionizing radiation (IR); cell survival and proliferation were assessed. Expression patterns of different kinase receptors and ligands were investigated using gene arrays. MSCs were highly sensitive to the tyrosine kinase inhibitors SU14816 (imatinib) and SU11657 (sunitinib), but showed only moderate sensitivity to the selective TGFβ receptor 1 inhibitor LY2109761. Primary adult human fibroblasts were comparably resistant to all three inhibitors. The addition of IR had an additive or supra-additive effect in the MSCs, but this was not the case for differentiated fibroblasts. Proliferation was markedly reduced in MSCs following kinase inhibition, both with and without IR. Gene expression analysis revealed high levels of the PDGF α and β receptors, and lower levels of the TGFβ receptor 2 and Abl kinase. IR did not alter the expression of kinase receptors or their respective ligands in either MSCs or adult fibroblasts. These data show that MSCs are highly sensitive to RKIs and combination treatments incorporating IR. Expression analyses suggest that high levels of PDGF receptors may contribute to this effect. (orig.) [German] Mesenchymale Stammzellen (MSCs) koennen die Geweberegeneration unterstuetzen und haben daher moeglicherweise eine Rolle bei der Reparatur

Breast cancers radiation-resistance: key role of the cancer stem cells marker CD24

International Nuclear Information System (INIS)

Bensimon, Julie

2013-01-01

This work focuses on the characterization of radiation-resistant breast cancer cells, responsible for relapse after radiotherapy. The 'Cancer Stem Cells' (CSC) theory describes a radiation-resistant cellular sub-population, with enhanced capacity to induce tumors and proliferate. In this work, we show that only the CSC marker CD24-/low defines a radiation resistant cell population, able to transmit the 'memory' of irradiation, expressed as long term genomic instability in the progeny of irradiated cells. We show that CD24 is not only a marker, but is an actor of radiation-response. So, CD24 expression controls cell proliferation in vitro and in vivo, and ROS level before and after irradiation. As a result, CD24-/low cells display enhanced radiation-resistance and genomic stability. For the first time, our results attribute a role to CD24-/low CSCs in the transmission of genomic instability. Moreover, by providing informations on tumor intrinsic radiation-sensitivity, CD24- marker could help to design new radiotherapy protocols. (author)

Destruction of radiation-resistant cell populations by hyperthermia

International Nuclear Information System (INIS)

Roettinger, E.M.; Gerweck, L.E.

1979-01-01

Animal experiments with local hyperthermia have shown that the radiauion dose necessary for the local control of 50% of the tumours examined was essentially reduced by heating to 42,5 0 C. In-vitro experients indicated selective destruction of relatively radiation-resistent cell populations by the combination of hyperthermie and reduced hydrogen ion concentration. Experiments with glioblastoma cells confirmed these results qualitatively, but showed quantitatively considerably lower sensitivity towards hyperthermia. (orig.) 891 MG/orig. 892 RDG [de

Radiation hard solar cell and array

International Nuclear Information System (INIS)

Russell, R.L.

1975-01-01

A power generating solar cell for a spacecraft solar array is hardened against transient response to nuclear radiation while permitting normal operation of the cell in a solar radiation environment by shunting the cell with a second solar cell whose contacts are reversed relative to the power cell to form a cell module, exposing the power cell only to the solar radiation in a solar radiation environment to produce an electrical output at the module terminals, and exposing both cells to the nuclear radiation in a nuclear radiation environment so that the radiation induced currents generated by the cells suppress one another

A biphasic radiation survival response of mammalian cells to molecular oxygen

International Nuclear Information System (INIS)

Millar, B.C.; Fielden, E.M.; Steele, J.J.

1979-01-01

A study has been made of the responses of exponentially growing monolayers of Chinese hamster cells to γ-irradiation at low oxygen concentrations. Survival data showed progressively more sensitization with increasing oxygen concentration in the range 0.4 to 1.5 μM, but a constant amount of sensitization between 1.5 and 7.0 μM. Further sensitization was achieved at greater oxygen concentrations. The data imply that there are at least two components to the radiation inactivation of this cell line, and the full oxygen effect curve cannot be described in terms of a single competitive mechanism. (UK)

Sensitization of rat 9L gliosarcoma cells to low dose rate irradiation by long duration 41 degrees C hyperthermia.

Science.gov (United States)

Armour, E P; Wang, Z H; Corry, P M; Martinez, A

1991-06-15

Modification of survival by long duration, 41 degrees C hyperthermia in combination with low dose rate radiation (0.5 Gy/h) was determined in rat 9L gliosarcoma cells. Cells were exposed to radiation in a manner that simulated continuous irradiation at a dose rate relevant to clinical brachytherapy. High dose rate X-irradiation was fractionated in 1.0-Gy fractions at 2-h intervals (FLDRI). Previous studies had demonstrated that 9L cells exposed to FLDRI with these parameters have survival characteristics that are equivalent to continuous low dose rate irradiation. Cells exposed to 41 degrees C throughout FLDRI were sensitized significantly (thermal enhancement ratio of 2.07) compared with cells irradiated at 37 degrees C. Incubation for 24 h at 41 degrees C before and/or after FLDRI at either 37 degrees C or 41 degrees C did not increase the slope of the radiation survival curves but did reduce the shoulder. Similarly, heating at 43 degrees C for 30 or 60 min before and/or after irradiation at 0.5 Gy/h also did not enhance cell sensitivity. Survival of cells after irradiation at high dose rate (60 Gy/h) was independent of the temperature during irradiation. Preheat at 41 degrees C for 24 h did not sensitize cells to high dose rate irradiation by increasing the slope of the survival curve, although a loss of shoulder was observed. Sensitization of cells heated at 43 degrees C for 30 or 60 min before high dose rate irradiation was expressed as classical slope modification. Our results demonstrate that 41 degrees C heating during FLDRI greatly sensitizes cells to radiation-induced killing for exposure durations up to 36 h. Heating 9L cells at 41 degrees C or 43 degrees C adjacent to FLDRI at 0.5 Gy/h resulted in no additional enhancement of terminal sensitivity, although shoulder modification was observed. The sensitization by simultaneous heating described above occurred even though thermotolerance developed during extended incubation at 41 degrees C. These in vitro

Radiation sensitivity of integrated circuits Pt. 1

International Nuclear Information System (INIS)

Bereczkine Kerenyi, Ilona

1986-01-01

The cosmic ray sensitivity of CMOS integrated circuits are overviewed in three parts. The aim is to analyze the effects of ionizing radiation on the degradation of electronic parameters, the effects of the electric state during irradiation, and the radiation hardening of ICs. In this Part 1 a general introduction of the response of semiconductors to cosmic radiation is given, and the radiation tolerance and hardening of small-scale integrated CMOS ICs is analyzed in detail. The devices include various basic inverters and simple gate ICs. (R.P.)

Differential biological effects of iodoacetate in mammalian cell lines; radio sensitization and radio protection

International Nuclear Information System (INIS)

Yadav, Usha; Anjaria, K.B.; Desai, Utkarsha N.; Chaurasia, Rajesh K.; Shirsath, K.B.; Bhat, Nagesh N.; Balakrishnan, Sreedevi; Sapra, B.K.; Nairy, Rajesha

2014-01-01

There are several studies where it has been shown that Iodoacetate (IA) possesses in vivo anti-tumor activity. The fact that it is a model glycolytic inhibitor makes it more interesting. As seen in recent trends, glycolytic inhibitors are emerging as new strategy for cancer therapeutic research taking advantage of glycolytic phenotype of cancerous tissues. IA has been reported to have radioprotective effects in yeast cells and human lymphocytes. Biological effects of IA in response to radiation in mammalian cell lines are not well documented. We screened IA for cytotoxicity using clonogenic assay at different concentrations ranging from 0.1 to 2.5 μg/ml using three different mammalian cell lines; A-549 (human lung carcinoma cell line), MCF-7 (human mammary cancer cell line) and a noncancerous CHO (Chinese hamster ovary cell line). For studying radioprotective/radio sensitizing efficacy, cells were exposed to 4 Gy of 60 Co-γ radiation using a teletherapy source at a dose rate of 1 Gy/min, following which IA post-treatment was carried out. Clonogenic and micronucleus assay were performed to assess radioprotection/sensitization. The results indicated that IA was highly cytotoxic in cancerous cell lines A-549 (IC 50 =1.25 μg/ml) and MCF-7 (IC 50 = 1.9 μg/ml). In contrast, it was totally non-toxic in non-cancerous cell line, viz. CHO, in the same concentration range. In addition, IA exhibited radio protective effect in CHO cell line, whereas in other two cancer cell lines, viz. A-549 and MCF-7, radio sensitizing effect was seen as judged by induction of cell killing and micronuclei. In conclusion, lA, a model glycolytic inhibitor, was found to be selectively cytotoxic in cancer cells as compared to normal cells. Further, it reduced radiation induced damage (micronuclei and cell killing) in normal cells but increased it in cancer cells indicating its potential use in cancer therapy. (author)

MicroRNA-221 and -222 Regulate Radiation Sensitivity by Targeting the PTEN Pathway

International Nuclear Information System (INIS)

Zhang Chunzhi; Kang Chunsheng; Wang Ping; Cao Yongzhen; Lv Zhonghong; Yu Shizhu; Wang Guangxiu; Zhang Anling; Jia Zhifan; Han Lei; Yang Chunying; Ishiyama, Hiromichi; Teh, Bin S.; Xu Bo; Pu Peiyu

2011-01-01

Purpose: MicroRNAs (miRNAs) are noncoding RNAs inhibiting expression of numerous target genes by posttranscriptional regulation. miRNA-221 and miRNA-222 (miRNA-221/-222) expression is elevated in radioresistant tumor cell lines; however, it is not known whether and how miRNAs control cellular responses to ionizing irradiation. Methods and Materials: We used bioinformatic analyses, luciferase reporter assay, and genetic knockdown and biochemical assays to characterize the regulation pathways of miRNA-221/-222 in response to radiation treatment. Results: We identified the PTEN gene as a target of miRNA-221/-222. Furthermore, we found that knocking down miRNA-221/-222 by antisense oligonucleotides upregulated PTEN expression. Upregulated PTEN expression suppressed AKT activity and increased radiation-induced apoptosis, resulting in enhancement of radiosensitivity in tumor cells. Conclusions: miRNA-221/-222 control radiation sensitivity by regulating the PTEN/AKT pathway and can be explored as novel targets for radiosensitization.

DNA replication and repair in Tilapia cells. 1. The effect of ultraviolet radiation

Energy Technology Data Exchange (ETDEWEB)

Yew, F.H.; Chang, L.M. (National Taiwan Univ., Taipei (China))

1984-12-01

The effect of ultraviolet radiation on a cell line established from the warm water fish Tilapia has been assessed by measuring the rate of DNA synthesis, excision repair, post-replication repair and cell survival. The cells tolerate ultraviolet radiation better than mammalian cells with respect to DNA synthesis, post-replication repair and cell survival. They are also efficient in excision repair, which in other fish cell lines has been found to be at a low level or absent. Their response to the inhibitors hydroxyurea and 1-..beta..-D-arabinofuranosylcytosine is less sensitive than that of other cell lines, yet the cells seem to have very small pools of DNA precursor.

Immunological aspects of light radiation sensitivity

International Nuclear Information System (INIS)

Hellman, K.B.; Schuller, G.B.

1981-01-01

The immune system comprises one aspect of the host's defense mechanism against potentially harmful agents. It has become recognized as an important factor in light radiation sensitivity and light-mediated disease. The interaction of light radiation with the immune system has formed the basis for the evolving discipline of photoimmunology. A description of the multicomponent immune system, its modification by light radiation, and a discussion of how photoimmunological studies may provide data important for understanding the mechanisms involved in photosensitivity are presented in this review. Photosensitivity may be either acquired or may be genetic in nature. Acquired photosensitivity involves an individual's reaction to either light alone or light in conjunction with topically or systemically administered photosenitizing agents. The outcome of such a reaction can be benign or severe, depending on a number of factors. Genetic photosensitivity includes the reactions to light radiation of individuals carrying the genetic information for inherited diseases such as Ataxia telangiectasia (AT) and Xeroderma pigmentosum (XP). Factors associated with these conditions can lead to enhanced sensitivity to radiation-related diseases, such as cancer. In addition, there are conditions which cannot be readily placed in either of the categories just described but, nevertheless, have been correlated with immune system dysfunction. These include photoallergy, photosensitivity associated with autoimmunity, and light-induced skin cancer. Immunological studies have provided information which may aid in elucidating the problem of photosensitivity and in the development of suitable radioprotective measures

Association of polymorphism in TP53 gene with susceptibility and radiation sensitivity of non-small-cell-lung cancer in Chinese population

International Nuclear Information System (INIS)

Shao Guoguang; Liu Linlin; Xu Chuanjie

2005-01-01

Objective: To study the association of polymorphism in TP53 gene with the susceptibility and radiation sensitivity of non-small-cell-lung cancer (NSCLC) of the population in the North of China. Methods: Using RFLP-PCR assays, TP53 genotypes were detected by amplifying DNA fragments with sequence specific primers and digested by FnuD II enzyme in 88 patients with NSCLC as well as 112 healthy controls. Results: The C/C allele frequency was significantly higher in NSCLC patients than that in the healthy controls (χ 2 =5.65, P=0.017). The C/C genotype frequency was significantly higher in NSCLC patients than that of the healthy controls (χ 2 =9.33, P=0.0023). The risk of C/C homozygotes in NSCLC patients was about 2.7 times against G/G homozygotes with odds ratio of 2.43(95% CI=1.32-4.51). Conclusion: In the population in the North of China, TP53 C/C genotype is closely associated with the susceptibility of NSCLC. There is no significant relationship between the polymorphism in TP53 gene and radiation sensitivity in NSCLC. (authors)

Do intracellular thiol or peroxidase levels block radiation sensitization by nitrous oxide in some E. coli strains

Energy Technology Data Exchange (ETDEWEB)

Ewing, D.; Guilfoil, D.S.; Ohm, M.B. (Hahnemann Univ., Philadelphia, PA (USA). Dept. of Radiation Oncology and Nuclear Medicine)

1991-01-01

Although nitrous oxide (N{sub 2}O) is often a radiation sensitizer in procaryotic cells, it fails to sensitize some strains of bacteria, some yeast strains, and most eucaryotic cell lines. At present this inconsistency cannot be satisfactorily explained. The experiments here use eight strains of E. coli, some of which are not sensitized by N{sub 2}O, to test the hypotheses that N{sub 2}O's failure to sensitize might be based on high thiol content or on low peroxidase activity. Our data contradict those hypotheses. In addition, further data show that the strains not sensitized by N{sub 2}O contain no unique cellular component or compound which blocks damage from N{sub 2}O. (author).

Inhibition of COX-2 expression by topical diclofenac enhanced radiation sensitivity via enhancement of TRAIL in human prostate adenocarcinoma xenograft model

Science.gov (United States)

2013-01-01

Background COX-2 inhibitors have an antitumor potential and have been verified by many researchers. Treatment of cancer cells with external stressors such as irradiation can stimulate the over-expression of COX-2 and possibly confer radiation resistance. In this study, we tested if topical diclofenac, which inhibits both COX-1 and COX-2, administration rendered prostate tumor cells sensitize to the effects of radiation. Methods LNCaP-COX-2 and LNCaP-Neo cells were treated with 0 to 1000 μM diclofenac. Next, a clonogenic assay was performed in which cells were subjected to irradiation (0 to 4 Gy) with or without diclofenac. COX-2 expression and other relevant molecules were measured by real-time PCR and immunohistochemistry after irradiation and diclofenac treatment. In addition, we assessed the tumor volumes of xenograft LNCaP-COX-2 cells treated with topical diclofenac with or without radiation therapy (RT). Results LNCaP-COX-2 and LNCaP-Neo cell lines experienced cytotoxic effects of diclofenac in a dose related manner. Clonogenic assays demonstrated that LNCaP-COX-2 cells were significantly more resistant to RT than LNCaP-Neo cells. Furthermore, the addition of diclofenac sensitized LNCaP-COX-2 not but LNCaP-Neo cells to the cytocidal effects of radiation. In LNCaP-COX-2 cells, diclofenac enhanced radiation-induced apoptosis compared with RT alone. This phenomenon might be attributed to enhancement of RT-induced TRAIL expression as demonstrated by real-time PCR analysis. Lastly, tumor volumes of LNCaP-COX-2 cells xenograft treated with diclofenac or RT alone was >4-fold higher than in mice treated with combined diclofenac and radiation (pdiclofenac enhances the effect of RT on prostate cancer cells that express COX-2. Thus, diclofenac may have potential as radiosensitizer for treatment of prostate cancer. PMID:23289871

Cell Cycle Regulation and Apoptotic Responses of the Embryonic Chick Retina by Ionizing Radiation.

Directory of Open Access Journals (Sweden)

Margot Mayer

Full Text Available Ionizing radiation (IR exerts deleterious effects on the developing brain, since proliferative neuronal progenitor cells are highly sensitive to IR-induced DNA damage. Assuming a radiation response that is comparable to mammals, the chick embryo would represent a lower vertebrate model system that allows analysis of the mechanisms underlying this sensitivity, thereby contributing to the reduction, refinement and replacement of animal experiments. Thus, this study aimed to elucidate the radiation response of the embryonic chick retina in three selected embryonic stages. Our studies reveal a lack in the radiation-induced activation of a G1/S checkpoint, but rapid abrogation of G2/M progression after IR in retinal progenitors throughout development. Unlike cell cycle control, radiation-induced apoptosis (RIA showed strong variations between its extent, dose dependency and temporal occurrence. Whereas the general sensitivity towards RIA declined with ongoing differentiation, its dose dependency constantly increased with age. For all embryonic stages RIA occurred during comparable periods after irradiation, but in older animals its maximum shifted towards earlier post-irradiation time points. In summary, our results are in good agreement with data from the developing rodent retina, strengthening the suitability of the chick embryo for the analysis of the radiation response in the developing central nervous system.

Combined action of radiation, salts of copper and nickel on cell viability in vitro

Directory of Open Access Journals (Sweden)

D. D. Gapeenko

2014-09-01

Full Text Available Experimental study of the combined action of heavy metals and ionizing radiation on the viability of cells in culture was made. We established a significant toxic effect of copper and nickel in the proliferative and mitotic activity of cells in vitro. Under the combined effects of radiation and copper ions on cells we observed the mor-phological changes in morphologically-functional properties of cells that were determined by or radiation dose or by concentration of copper ions. While incubation of irradiated cells with nickel ions we observed sensitiza-tion of cells by nickel ions under the irradiation dose of 0.5 and 5.0 Gy, and the resistance of cells to exposure to sublethal dose of 10.0 Gy.

Sensitization to radiation and alkylating agents by inhibitors of poly(ADP-ribose) polymerase is enhanced in cells deficient in DNA double-strand break repair.

Science.gov (United States)

Löser, Dana A; Shibata, Atsushi; Shibata, Akiko K; Woodbine, Lisa J; Jeggo, Penny A; Chalmers, Anthony J

2010-06-01

As single agents, chemical inhibitors of poly(ADP-ribose) polymerase (PARP) are nontoxic and have clinical efficacy against BRCA1- and BRCA2-deficient tumors. PARP inhibitors also enhance the cytotoxicity of ionizing radiation and alkylating agents but will only improve clinical outcomes if tumor sensitization exceeds effects on normal tissues. It is unclear how tumor DNA repair proficiency affects the degree of sensitization. We have previously shown that the radiosensitizing effect of PARP inhibition requires DNA replication and will therefore affect rapidly proliferating tumors more than normal tissues. Because many tumors exhibit defective DNA repair, we investigated the impact of double-strand break (DSB) repair integrity on the sensitizing effects of the PARP inhibitor olaparib. Sensitization to ionizing radiation and the alkylating agent methylmethane sulfonate was enhanced in DSB repair-deficient cells. In Artemis(-/-) and ATM(-/-) mouse embryo fibroblasts, sensitization was replication dependent and associated with defective repair of replication-associated damage. Radiosensitization of Ligase IV(-/-) mouse embryo fibroblasts was independent of DNA replication and is explained by inhibition of "alternative" end joining. After methylmethane sulfonate treatment, PARP inhibition promoted replication-independent accumulation of DSB, repair of which required Ligase IV. Our findings predict that the sensitizing effects of PARP inhibitors will be more pronounced in rapidly dividing and/or DNA repair defective tumors than normal tissues and show their potential to enhance the therapeutic ratio achieved by conventional DNA-damaging agents.

Radiation-induced enhancement of enzymatic cell lysis of Micrococcus radiodurans

International Nuclear Information System (INIS)

Watanabe, H.; Takehisa, M.; Iizuka, H.

1981-01-01

The intact cells of M. radiodurans were rendered sensitive to the action of lytic enzyme (P2-2 enzyme) by irradiation. The radiation-induced enhancement of cell lysis with P2-2 enzyme was completely prevented by the addition of t-butanol and irradiation at liquid nitrogen temperature. These results indicate that the enhancement is due to indirect action resulting from OH radicals. Cell lysis by lysozyme was enhanced only when the cells were irradiated under N 2 O. The enhancement of cell lysis with lysozyme was also prevented by adding alcohols. On the other hand, when lipid components in cells were removed by extraction with n-butanol, the radiation-induced enhancement of cell lysis with P2-2 enzyme and lysozyme was not observed. From these results it is concluded that the enhancement of enzymatic cell lysis by irradiation is attributable to alteration in the lipid-rich layer of the cell wall caused by OH radicals

Radiation-induced enhancement of enzymatic cell lysis of Micrococcus radiodurans

Energy Technology Data Exchange (ETDEWEB)

Watanabe, H.; Takehisa, M. [Japan Atomic Energy Research Inst., Takasaki, Gunma, Takasaki Radiation Chemistry Research Establishment (Japan); Iizuka, H.

1981-10-15

The intact cells of M. radiodurans were rendered sensitive to the action of lytic enzyme (P2-2 enzyme) by irradiation. The radiation-induced enhancement of cell lysis with P2-2 enzyme was completely prevented by the addition of t-butanol and irradiation at liquid nitrogen temperature. These results indicate that the enhancement is due to indirect action resulting from OH radicals. Cell lysis by lysozyme was enhanced only when the cells were irradiated under N{sub 2}O. The enhancement of cell lysis with lysozyme was also prevented by adding alcohols. On the other hand, when lipid components in cells were removed by extraction with n-butanol, the radiation-induced enhancement of cell lysis with P2-2 enzyme and lysozyme was not observed. From these results it is concluded that the enhancement of enzymatic cell lysis by irradiation is attributable to alteration in the lipid-rich layer of the cell wall caused by OH radicals.

Retinopathy secondary to radiation therapy for squamous cell carcinoma

International Nuclear Information System (INIS)

Groomer, A.E.; Gutwein, D.E.

1989-01-01

This report discusses a case of radiotherapy-induced retinopathy following treatment of squamous cell carcinoma. Treatment of the carcinoma with external beam radiotherapy to the supraorbital region and base of the skull was followed by the onset of retinopathy. The sensory retina, as well as other central nervous system tissues, is highly resistant to radiation damage; however, the retinal vasculature is extremely sensitive to radiation damage, producing a retinopathy that is characteristic of other vascular occlusive diseases. Management is discussed

Differential response to gamma radiation of human stomach cancer cells in vitro

International Nuclear Information System (INIS)

Jenkins, V.K.; Barranco, S.C.; Townsend, C.M. Jr.; Perry, R.R.; Ives, K.L.

1986-01-01

In vitro effects of radiation were studied in two permanent cell lines (AGS and SII) from two patients with stomach adenocarcinoma and three permanent sublines from each cell line. Radiation survival parameters for AGS and SII parent cell lines and sublines were determined after in vitro irradiation with 0.5 to 10 Gy of 60 Co gamma rays. AGS and SII cell lines had different growth properties. DNA contents and radiation survival curves. Surviving fractions of SII parent cells (76 chromosomes) after 2.0 and 10 Gy were 1.22 and 17.8 times greater, respectively, than values for AGS parent cells (47 chromosomes). Sensitivities (D 0 ) were 1.08 and 1.45 Gy for AGS and SII parent lines, respectively. D 0 values for AGS parent cells and sublines were similar (1.01 to 1.08 Gy), but SII parent cells and sublines had D 0 values of 1.45, 1.36, 1.37 and 1.12 Gy (for SII-A). The SII parent cells had survival fractions after 2.0 and 10 Gy that were 1.3 and 11.3 times greater, respectively, than values for the SII-A cells. These data show differences in radiation responses among stomach cancer cell lines and sublines that may relate to DNA content, but there was no consistent correlation between radiation response and a particular cell characteristic. (author)

Glow discharge, its sensitivity to infra-red radiation. Observations made during the testing of multiwire proportional chambers

International Nuclear Information System (INIS)

Marsh, J.B.; Souten, K.H.; O'Hagan, B.

1979-05-01

It has been shown that under glow discharge conditions, multiwire proportional chambers are sensitive to infra-red radiation. Discharge current measurements and light change measurements have been made and the effect of the input window on the output signal and the importance of the finish of the anode and HT wires have been investigated. From these observations it would appear that a glow discharge in the form detailed in this report is sensitive to infra-red radiation though work is still required to optimise the parameters of such a device for IR detection or solar cell technology. (UK)

In vitro study of cytotoxicity by U.V. radiation and differential sensitivity in combination with alkylating agents on established cell systems

International Nuclear Information System (INIS)

Ramudu, K.

1991-01-01

The effect of U.V. radiation or alkylating agents, such as actinomycin-D, cycloheximide and mitomycin-C (MMC), was studied on CHO, BHK and HeLa cells. U.V. radiation caused DNA ssb and dsb and were prevented by cycloheximide and actinomycin-D. MMC is known to be cytotoxic in CHO/BHK cells by forming free radical generation. MMC in combination with U.V. radiation enhanced DNA ssb ampersand dsb in these cell types. However, HeLa cells were insensitive to U.V. radiation. This insensitivity to U.V. radiation could be ascribed to the presence of glutathione transferase which is absent in CHO/BHK cell line

Comparative studies on the effect of radiation-sensitizing agents used in radiating VX2 Carcinoma. With reference to 5-bromodeoxyuridine (BUdR)

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Migita, H [Kyushu Dental Coll., Kitakyushu, Fukuoka (Japan)

1975-11-01

The effects of 5-Fu and BUdR as radiation-sensitizing agents macroscopically were investigated in 122 VX2 Carcinomas transplanted into the calves of the hind legs of rabbits. Experimental groups and contrast groups are divided into six as follows: A: No treatment, B: 5-Fu infusion, C: BUdR+Antimetabolite infusion, D: Radiation, E: 5-Fu infusion and radiation, and F: BUdR+Antimetabolite infusion and radiation. The amount of agent given to each was 5 mg/kg/day of 5-Fu and 50 mg/kg/day of BUdR, and the amount of radiation was 300 rad/day. 5-Fu was used as the Antimetabolite, and its amount was one-tenth of that in the 5-Fu Infusion Group. The agent and the radiation were given for five days. 1. In the 300 rad/day Group, the radiation was not enough to result in a complete cure. 2. In the two Agent Infusion Group, 5-Fu and BUdR+Antimetabolite proved to be anti-cancer, but neither of them resulted in effective treatment. 3. The 5-Fu Infusion and Radiation Group, showed a strong degenerative change in the tumor cell and a radiosensitive effect from 5-Fu, but the tumor was not lessened. 4. In the BUdR-Antimetabolite Infusion and Radiation Group, the tumor began to reduce on the third day. On the seventh and fourteenth days, necrosis of the greater part of tumor was seen, and the rest of the tumor cells were found to be in degenerative change. On the twenty first day, no live tumor cell was found, only dead remains of tumor cells. The results were confirmed both macroscopically and histopathologically. 5. BUdR can be expected to be effective in clinical application to oral malignant tumors.

Radio-sensitivity of the cells from amyotrophic lateral sclerosis model mice transfected with human mutant SOD1

International Nuclear Information System (INIS)

Wate, Reika; Ito, Hidefumi; Kusaka, Hirofumi; Takahashi, Sentaro; Kubota, Yoshihisa; Suetomi, Katsutoshi; Sato, Hiroshi; Okayasu, Ryuichi

2005-01-01

In order to clarify the possible involvement of oxidative damage induced by ionizing radiation in the onset and/or progression of familial amyotrophic lateral sclerosis (ALS), we studied radio-sensitivity in primary cells derived from ALS model mice expressing human mutant Cu/Zn superoxide dismutase (SOD1). The primary mouse cells expressed both mouse and the mutant human SOD1. The cell survival of the transgenic mice (with mutant SOD1), determined by counting cell numbers at a scheduled time after X-irradiation, is very similar to that of cells from wild type animals. The induction and repair of DNA damage in the transgenic cells, measured by single cell gel electrophoresis and pulsed field gel electrophoresis, are also similar to those of wild type cells. These results indicate that the human mutant SOD1 gene does not seem to contribute to the alteration of radio-sensitivity, at least in the fibroblastic cells used here. Although it is necessary to consider the difference in cell types between fibroblastic and neuronal cells, the present results may suggest that ionizing radiation is not primarily responsible for the onset of familial ALS with the SOD1 mutation, and that the excess risks are probably not a concern for radiation diagnosis and therapy in familial ALS patients. (author)

Inhibition of phosphatidylinositol-3-kinase causes increased sensitivity to radiation through a PKB-dependent mechanism

International Nuclear Information System (INIS)

Gottschalk, Alexander R.; Doan, Albert; Nakamura, Jean L.; Stokoe, David; Haas-Kogan, Daphne A.

2005-01-01

Purpose: To identify whether inhibition of phosphatidylinositol-3-kinase (PI3K) causes increased radiosensitivity through inhibition of protein kinase B (PKB), implicating PKB as an important therapeutic target in prostate cancer. Methods and Materials: The prostate cancer cell line LNCaP was treated with the PI3K inhibitor LY294002, radiation, and combinations of the two therapies. Apoptosis and survival were measured by cell cycle analysis, Western blot analysis for cleaved poly (ADP-ribose) polymerase, and clonogenic survival. To test the hypothesis that inhibition of PKB is responsible for LY294002-induced radiosensitivity, LNCaP cells expressing a constitutively active form of PKB were used. Results: The combination of PI3K inhibition and radiation caused an increase in apoptosis and a decrease in clonogenic survival when compared to either modality alone. The expression of constitutively activated PKB blocked apoptosis induced by combination of PI3K inhibition and radiation and prevented radiosensitization by LY294002. Conclusion: These data indicate that PI3K inhibition increases sensitivity of prostate cancer cell lines to ionizing radiation through inactivation of PKB. Therefore, PTEN mutations, which lead to PKB activation, may play an important role in the resistance of prostate cancer to radiation therapy. Targeted therapy against PKB could be beneficial in the management of prostate cancer patients

DNA from radiation resistant human tumor cells transfers resistance to NIH/3T3 cells with varying degrees of penetrance

International Nuclear Information System (INIS)

Kasid, U.; Dritschilo, A.; Weichselbaum, R.

1987-01-01

Experimental evidence suggests that clinical radiation resistance may correlate with in vitro radiation survival parameters. Specifically, they isolated several cell lines from radioresistant head and neck carcinomas with D/sub 0/ values greater than 2 Gy. The authors co-transfected DNA from cell line SQ2OB (D/sub 0/ = 2.4 Gy) with the rhoSVNeO plasmid into NIH/3T3 cells (D/sub 0/ = 1.7 Gy). Antibiotic G418 resistant, transformed clones were isolated and confirmed by Southern blotting to contain human alu, as well as rhoSVNeO sequences. Screening for radiation resistance with 8Gy (Cs-137) revealed that 3 of 4 tested hybrid clones show a radiation survival intermediate between NIH/3T3 and SQ2OB. This suggests that radiation resistance is a dominant, transfectable phenotype of mammalian cells and can be expressed in more sensitive cells. Karyotyping of resistant hybrid clones shows the presence of double minute chromosomes. Secondary transfection results and experiments to clone the genetic factors responsible for radiation resistance are in progress and results will be reported

Effect of single-dose radiation on cell survival and growth hormone secretion by rat anterior pituitary cells

International Nuclear Information System (INIS)

Hochberg, Z.; Kuten, A.; Hertz, P.; Tatcher, M.; Kedar, A.; Benderly, A.

1983-01-01

Cranial irradiation has been shown to impair growth hormone secretion in children. In this study a cell culture of dispersed rat anterior pituitary cells was exposed to single doses of radiation in the range of 100 to 1500 rad. Survival curves were obtained for the different anterior pituitary cell lines, and growth hormone secretion was measured in the tissue culture medium. Both survival and growth hormone secretion curves showed an initial shoulder in the range of 0 to 300 rad, followed by a decline between 300 to 750 rad. It is concluded that growth hormone secreting acidophilic pituicytes are sensitive to radiation at single doses greater than 300 rad

Effect of recombinant adenovirus encoding human p53 tumor suppressor gene combined with radiation therapy on human lymphoma cells lines

International Nuclear Information System (INIS)

Yu Zeyang; Fan Wo; Li Dongqing; Zhu Ran; Wan Jianmei; Wang Yongqing; Wu Jinchang

2008-01-01

This paper analyzes the inhibitory effect and radiation sensitization of recombinant adenovirus encoding human p53 tumor suppressor gene (rAd-p53) on human lymphoma cell lines. Human lymphoma cell lines were treated with rAd-p53, radiation therapy and combined treatment, respectively. The cell growth inhibition was assessed by MTF. The cell cycle and apoptosis were detected by flow cytometry, and the p53 protein expression was detected by Western blotting. The results showed that extrinsic p53 gene have expressed to some degree, but not at high level. The role of inhibition and radiation sensitivity of rAd-p53 was not significant to human lymphoma cell lines. (authors)

Enhanced radiation response in radioresistant MCF-7 cells by targeting peroxiredoxin II

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Diaz AJG

2013-10-01

Full Text Available Anthony Joseph Gomez Diaz,1 Daniel Tamae,2 Yun Yen,3 JianJian Li,4 Tieli Wang1 1Department of Chemistry and Biochemistry, California State University at Dominguez Hills, Carson, CA, 2Center of Excellence in Environmental Toxicology, Department of Pharmacology, University of Pennsylvania, Philadelphia, PA, 3Department of Clinical and Molecular Pharmacology, Beckman Research Institute of City of Hope National Medical Center, Duarte, CA, 4Department of Radiation Oncology, University of California Davis, Sacramento, CA, USA Abstract: In our previous study, we identified that a protein target, peroxiredoxin II (PrxII, is overexpressed in radioresistant MCF+FIR3 breast-cancer cells and found that its expression and function is associated with breast-cancer radiation sensitivity or resistance. Small interference RNA (siRNA targeting PrxII gene expression was able to sensitize MCF+FIR3 radioresistant breast-cancer cells to ionizing radiation. The major focus of this work was to investigate how the radiation response of MCF+FIR3 radioresistant cells was affected by the siRNA that inhibits PrxII gene expression. Our results, presented here, show that silencing PrxII gene expression increased cellular toxicity by altering cellular thiol status, inhibiting Ca2+ efflux from the cells, and perturbing the intracellular Ca2+ homeostasis. By combining radiotherapy and siRNA technology, we hope to develop new therapeutic strategies that may have potential to enhance the efficacy of chemotherapeutic agents due to this technology's property of targeting to specific cancer-related genes. Keywords: siRNA, PrxII, radiation resistance, Ca2+, MCF+FIR3

[Influence of low doses of ionizing radiation on tenascin expression in hybridoma cell systems].

Science.gov (United States)

Lunga, I N

2003-01-01

One of the achievements of the modern radiation ecology is the preparation and application of stable eukariotic cell lines to solve various problems occurring under exposure to ionizing radiation, especially to low doses. The detection of onco-fetal protein--tenascin in different embryonic and tumor cells of humans and animals supposes the probability of appropriate gene expression in lymphoid cells, including hybridomal cells. Using the immunochemical method, the study of tenascin expression in two mouse hybridomal lines was carried out. Tenascin was revealed in hybridomal lines MLC-1 and K-48. Further hybridomal cell lines were exposed to X-ray radiation (120 KV) with doses 2.10,15 cGy. The obtained results demonstrated the sensitivity of tenascin expression to low doses of ionizing radiation, that may be used as a convenient model of studying of genotoxic effects of various damaging ionizing agents on a cell level.

Low-dose radiation employed in diagnostic imaging causes genetic effects in cultured cells

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Ponzinibbio, Maria V.; Peral-Garcia, Pilar; Seoane, Analia (Inst. de Genetica Veterinaria, Univ. Nacional de La Plata CONICET, La Plata (Argentina)), e-mail: aseoane@fcv.unlp.edu.ar; Crudeli, Cintia (Agencia Nacional de Promocion Cientifica y Tecnologica, La Plata (Argentina))

2010-11-15

Background: Exposure to environmental, diagnostic, and occupational sources of radiation frequently involves low doses. Although these doses have no immediately noticeable impact on human health there is great interest in their long-term biological effects. Purpose: To assess immediate and time-delayed DNA damage in two cell lines exposed to low doses of ionizing radiation by using the comet assay and micronucleus test, and to compare these two techniques in the analysis of low-dose induced genotoxicity. Material and Methods: CHO and MRC-5 cells were exposed to 50 milliSievert (mSv) of ionizing radiation and assayed immediately after irradiation and at 16 or 12 passages post-irradiation, respectively. Comet assay and micronucleus test were employed. Results: The comet assay values observed in 50 mSv-treated cells were significantly higher than in the control group for both sample times and cell lines (P < 0.001). Micronuclei frequencies were higher in treated cells than in the control group (P < 0.01, CHO cells passage 16; P < 0.05, MRC-5 cells immediately after exposure; P < 0.01 MRC-5 cells passage 12). Correlation analysis between the two techniques was statistically significant (correlation coefficient 0.82, P < 0.05 and correlation coefficient 0.86, P < 0.05 for CHO and MRC-5 cells, respectively). Cells scored at passages 12 or 16 showed more damage than those scored immediately after exposure in both cell lines (no statistically significant differences). Conclusion: Cytomolecular and cytogenetic damage was observed in cells exposed to very low doses of X-rays and their progeny. A single low dose of ionizing radiation was sufficient to induce such response, indicating that mammalian cells are exquisitely sensitive to it. Comet and micronucleus assays are sensitive enough to assess this damage, although the former seems to be more efficient

Low-dose radiation employed in diagnostic imaging causes genetic effects in cultured cells

International Nuclear Information System (INIS)

Ponzinibbio, Maria V.; Peral-Garcia, Pilar; Seoane, Analia; Crudeli, Cintia

2010-01-01

Background: Exposure to environmental, diagnostic, and occupational sources of radiation frequently involves low doses. Although these doses have no immediately noticeable impact on human health there is great interest in their long-term biological effects. Purpose: To assess immediate and time-delayed DNA damage in two cell lines exposed to low doses of ionizing radiation by using the comet assay and micronucleus test, and to compare these two techniques in the analysis of low-dose induced genotoxicity. Material and Methods: CHO and MRC-5 cells were exposed to 50 milliSievert (mSv) of ionizing radiation and assayed immediately after irradiation and at 16 or 12 passages post-irradiation, respectively. Comet assay and micronucleus test were employed. Results: The comet assay values observed in 50 mSv-treated cells were significantly higher than in the control group for both sample times and cell lines (P < 0.001). Micronuclei frequencies were higher in treated cells than in the control group (P < 0.01, CHO cells passage 16; P < 0.05, MRC-5 cells immediately after exposure; P < 0.01 MRC-5 cells passage 12). Correlation analysis between the two techniques was statistically significant (correlation coefficient 0.82, P < 0.05 and correlation coefficient 0.86, P < 0.05 for CHO and MRC-5 cells, respectively). Cells scored at passages 12 or 16 showed more damage than those scored immediately after exposure in both cell lines (no statistically significant differences). Conclusion: Cytomolecular and cytogenetic damage was observed in cells exposed to very low doses of X-rays and their progeny. A single low dose of ionizing radiation was sufficient to induce such response, indicating that mammalian cells are exquisitely sensitive to it. Comet and micronucleus assays are sensitive enough to assess this damage, although the former seems to be more efficient

Sensitivity to ionizing radiation and chemotherapeutic agents in gemcitabine-resistant human tumor cell lines

NARCIS (Netherlands)