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Sample records for cell radiosensitizer doranidazole

  1. Effects of hypoxic cell radiosensitizer doranidazole (PR-350) on the radioresponse of murine and human tumor cells in vitro and in vivo

    International Nuclear Information System (INIS)

    We have investigated the radiosensitizing effect of doranidazole, a hypoxic cells radiosensitizer, using SCCVII tumor cells of C3H mice and CFPAC-1 and MIA PaCa-2 human pancreatic tumor cells. The radiosensitivity of hypoxic SCCVII cells in vitro increased with 1 mM doranidazole by a factor of 1.34 and 1.68, when determined by clonogenic survival and micronucleus (MN) formation, respectively. The radiation-induced growth delay of SCCVII tumors was significantly enhanced and the radiation dose required to care to care 50% of tumors 120 days after irradiation (TCD50/120) was reduced by a factor of 1.33 when 200 mg/kg doranidazole was injected, i.v., 20 min prior to tumor irradiation. The in vivo-in vitro excision assay showed that radiosensitivity of SCCVII cells in vivo increased by a factor of 1.47 with 200 mg/kg doranidazole. The radiation-induced growth delay of CFPAC-1 xenografts in nude mice was significantly enhanced and the radiation dose required to care 50% of tumors 90 days after irradiation (TCD50/90) was reduced by a factor of 1.30 by 200 mg/kg doranidazole. On the other hand, 200 mg/kg of doranidazole exerted no influence on the radiation-induced growth delay in MIA PaCa-2 xenografts. The tumor oxygenation status, as determined with an oxygen sensitive needle probe and the immunohistological study using pimonidazole, indicated that MIA PaCa-2 tumors are better oxygenated than CFPAC-1 tumors. The relatively well-oxygenated status in MIA PaCa-2 tumor may account for the lack of radiosensitization by doranidazole. It is concluded that the magnitude of radiosensitization of tumors by doranidazole is dependent on the oxygenation status of the tumors and that doranidazole may be useful in increasing the response of hypoxic human pancreatic tumor to intraoperative radiotherapy (IORT). (author)

  2. The prospective application of a hypoxic radiosensitizer, doranidazole to rat intracranial glioblastoma with blood brain barrier disruption

    International Nuclear Information System (INIS)

    Glioblastoma is one of the intractable cancers and is highly resistant to ionizing radiation. This radioresistance is partly due to the presence of a hypoxic region which is widely found in advanced malignant gliomas. In the present study, we evaluated the effectiveness of the hypoxic cell sensitizer doranidazole (PR-350) using the C6 rat glioblastoma model, focusing on the status of blood brain barrier (BBB). Reproductive cell death in the rat C6 glioma cell line was determined by means of clonogenic assay. An intracranial C6 glioma model was established for the in vivo experiments. To investigate the status of the BBB in C6 glioma bearing brain, we performed the Evans blue extravasation test. Autoradiography with [14C]-doranidazole was performed to examine the distribution of doranidazole in the glioma tumor. T2-weighted MRI was employed to examine the effects of X-irradiation and/or doranidazole on tumor growth. Doranidazole significantly enhanced radiation-induced reproductive cell death in vitro under hypoxia, but not under normoxia. The BBB in C6-bearing brain was completely disrupted and [14C]-doranidazole specifically penetrated the tumor regions. Combined treatment with X-irradiation and doranidazole significantly inhibited the growth of C6 gliomas. Our results revealed that BBB disruption in glioma enables BBB-impermeable radiosensitizers to penetrate and distribute in the target region. This study is the first to propose that in malignant glioma the administration of hydrophilic hypoxic radiosensitizers could be a potent strategy for improving the clinical outcome of radiotherapy without side effects

  3. Phase I clinical trial for the effect of a radiosensitizer, PR-350 (Doranidazole), combined with intraoperative radiation therapy in the treatment of pancreatic carcinoma

    International Nuclear Information System (INIS)

    We tested the safety and efficacy of hypoxic cell sensitizer, PR-350 (Doranidazole), in conjunction with intraoperative electron beam radiation therapy (IORT) in patients with advanced adenocarcinoma of the pancreas. PR-350 was delivered intravenously at a dose of 400 to 2,000 mg/m2 in conjunction with IORT of 20 to 40 Gy applied to the pancreas. In 15 patients treated with PR-350, the blood concentration of PR-350 decreased rapidly and the mean half-time of 50% disappearance was 3.6∼5.0 hours. Eighty five percent of PR-350 was eliminated through the urine without any degradation. One patient showed a slight elevation of glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) values and another patient showed a slight decrease of blood pressure with bradycardia. As both patients recovered without any clinical problems, the adequate dose of PR-350 was determined as 2,000 mg/m2. We will move to the next clinical trial in order to clarify the effect of PR-350 combined with IORT on patients with locally advanced pancreatic cancer without liver metastasis using a double-blind study design. (author)

  4. Hypoxic cell radiosensitizers

    International Nuclear Information System (INIS)

    Hyperbaric oxygen results have demonstrated that there is a problem of hypoxid cells in some types of tumour, and that even small daily fractions with HBO can give improved results. Reasons are given for expecting radiosensitizing drugs to penetrate better than HBO to the hypoxic cells, which exist in tumours exceeding 1 or 2 mm diameter. Preliminary clinical studies have demonstrated significant effects on human tumours of misonidazole and metronidazole. Concentrations of misonidazole have been measured in human tumours which were 40-110% of those in plasma, usually 70-90%. A number of clinical trials are being initiated using misonidazole. Future clinical results of hypoxic cell radiosentizers will clarify further the role of hypoxic cells in causing resistance to radiotherapy. (orig./MG) 891 MG/orig.- 892 RDG

  5. Hypoxic cell radiosensitizer

    International Nuclear Information System (INIS)

    Since an unsuccessful clinical trial of Misonidazole, many investigations were carried out to find out the useful hypoxic cell radio-sensitizers all over the world. In the USA., Dr. M. Brown synthesized and tested SR-2508 and this drug is now on the phase II-III clinical trials. In the U.K., Dr. J. Adams proposed Ro-08-8799. In Japan, partly supported by the Ministry of Education, Science and Culture, a research group was formed and got an agreement to use the same screening system to evaluate newly synthesized drugs. Through this screening system, thousand of drugs were tested. Among these drugs, KU-2285, RK-28, RP-170 and KIH-801(2) showed remarkable sensitizing effects or minor toxicity. Right now, these drugs are on either phase I clinical trial or pre-clinical evaluations. (author)

  6. Radiosensitivity of mesothelioma cell lines

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

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    Čemažar, Maja; Grošel, Alenka; Kranjc, Simona; Pipan, Živa; Serša, Gregor

    2003-01-01

    Aim. Radiosensitization with cisplatin can be enhanced by electroporation of cells and tumours. The aim of this study was to extend our previous studies ontwo carcinoma tumour models with different chemo-and radiosensitivity in order to evaluate whether this treatment is effective also on less chemo-and radiosensitive tumour cells. Materials and methods. This in vitro study was performed on carcinoma SCK and EAT-E cells. The cytotoxicity of three-modalitytreatment consisting of cisplatin, ele...

  9. Radiosensitivity of synchronized Yoshida sarcoma cells

    International Nuclear Information System (INIS)

    Yoshida sarcoma cells were synchronized in vitro, and the cultures were irradiated with the Stabilipan pendulum unit under deep X-ray therapy conditions. Cellular proliferation after irradiation was measured in the cell culture and, after i.p. injection of the cells, in mice. The growth of unsynchronized cultures was inhibited by irradiation, depending on the radiation dose; the LD50 was 380 rad in vivo and 480 rad in vitro. In further investigations, the cultures were irradiated with 150, 300 and 450 rad, and the mitotic behaviour, the rates of proliferation, the incorporation of 3H-thymidine into DNA and of 14C-leucine into cell protein were measured. The mitotic index of unsynchronized cells decreases as a function of the radiation dose, starting 2 h after irradiation and with a peak after periods of different length. Incorporation into DNA of 3H-thymidine is inhibited by 20 to 40%, depending on the radiation dose. Incorporation into the cell proteins of 3H thymidine is inhibited by 10 to 30%, depending on the radiation dose. Synchronized cells were irradiated in the G1/S, S, G2 and G1 phases. As regards incorporation of 3H-thymidine and 14C-lencine and the mitotic index, there was no difference between synchronized cells and unsynchronized control cultures. However, in cultures irradiated in the G2 phase, growth was significantly inhibited in vivo 48 h later. This distinction between cells irradiated in the G2 phase and cells irradiated in other phases was blurred when the cells were cultivated for more than 72 h after irradiation. The higher radiosensitivity of G2 cells can be explained as being due to delayed cell division and does not suggest increased radiosensitivity of this phase. (orig./MG)

  10. Paraquat-induced radiosensitization of mammalian cells

    International Nuclear Information System (INIS)

    The herbicide, paraquat (methyl viologen, 1-1' dimethy1-4, 4'-bipyridinium dichloride), stimulates the production of superoxide anion (O2sup(-.)) in aerobic cells and therefore mimics some effects of ionizing radiation. In addition, concentrations of cellular glutathione are reduced by reaction with O2sup(-.). It is reported here that paraquat, toxic in its own right to aerobic cells, acts as a radiosensitizer when cells are exposed to nontoxic concentrations of the drug prior to and during irradiation. The radiomimetic effect of paraquat, alone and in combination with X-rays, was examined. Paraquat affects aerated cells (hamster lung V79 cells) in a dose-dependent manner. Doses in excess of 1 mM for two hours cause significant cell killing. In combination with radiation, sublethal doses of paraquat, given for two hours prior to irradiation, enhance the lethal effects of radiation. However, if cells are exposed to the same concentration of paraquat following irradiation, no additional lethal effect is observed. Paraquat is a useful tool to study the effects of O2sup(-.) and may lead to better understanding of the mechanisms of radiation-induced energy deposition in cells. (author)

  11. Radiosensitivity of cultured insect cells: I. Lepidoptera

    International Nuclear Information System (INIS)

    The radiosensitivity of five lepidopteran insect cell lines representing five different genera has been investigated. These lines are: (1) TN-368, Trichoplusia ni; (2) IPLB-SF-1254, Spodoptera frugiperda; (3) IPLB-1075, Heliothis zea; (4) MRRL-CHl, clone GVl, Manduca sexta; and (5) IAL-PID2, Plodia interpunctella. The cell lines grew at different rates and had population doubling times that ranged from 19 to 52 hr. All of the lines are highly heteroploid and have approximate chromosome numbers near or above 100. The chromosomes are very small. All of the lines are extremely radioresistant; cell populations are able to recover from 260 kVp X-ray exposures up to and including 400 Gy, the highest dose examined. Cell survival curves were obtainable for only the TN-368 and IPLB-SF-1254 lines. The TN-368 cells displayed a biphasic survival response with D0, d/sub q/, and n values of 65.7 and 130.2 Gy, 9.0 and -36.1 Gy, and 1.2 and 0.8, respectively, for the steep and shallow portions of the curve. The IPLB-SF-1254 cells had a D0 of 63.9 Gy. D/sub q/ of 19.0 Gy, and n value of 1.4. These studies provide definitive evidence of the radioresistance of lepidopteran cells, and suggest that this radioresistance is a characteristic of lepidopteran insects

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

    International Nuclear Information System (INIS)

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

  13. Radiosensitivity of Human Melanoma Cell Lines

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    Bergoc, R. M.; Medina, V.; Cricco, G.; Mohamed, N.; Martin, G.; Nunez, M.; Croci, M.; Crescenti, E. J.; Rivera, E. S.

    2004-07-01

    Cutaneous melanoma is a skin cancer resulting from the malign transformation of skin-pigment cells, the melanocytes. The radiotherapy, alone or in combination with other treatment, is an important therapy for this disease. the objective of this paper was to determine in vitro the radiosensitivity of two human melanoma cell lines with different metastatic capability: WM35 and MI/15, and to study the effect of drugs on radiobiological parameters. The Survival Curves were adjusted to the mathematical Linear-quadratic model using GrapsPad Prism software. Cells were seeded in RPMI medium (3000-3500 cells/flask), in triplicate and irradiated 24 h later. The irradiation was performed using an IBL 437C H Type equipment (189 TBq, 7.7 Gy/min) calibrated with a TLD 700 dosimeter. The range of Doses covered from 0 to 10 Gy and the colonies formed were counted at day 7th post-irradiation. Results obtained were: for WM35, {alpha}=0.37{+-}0.07 Gy''-1 and {beta}=0.06{+-}0.02 Gy''-2, for M1/15m {alpha}=0.47{+-}0.03 Gy''-1 and {beta}=0.06{+-}0.01 Gy''-2. The {alpha}/{beta} values WM35: {alpha}/{beta} values WM35: {alpha}/{beta}=6.07 Gy and M1/15: {alpha}/{beta}{sub 7}.33 Gy were similar, independently of their metastatic capabillity and indicate that both lines exhibit high radioresistance. Microscopic observation of irradiated cells showed multinuclear cells with few morphologic changes non-compatible with apoptosis. By means of specific fluorescent dyes and flow cytometry analysis we determined the intracellular levels of the radicals superoxide and hydrogen peroxide and their modulation in response to ionizing radiation. The results showed a marked decreased in H{sub 2}O{sub 2} intracellular levels with a simultaneous increase in superoxide that will be part of a mechanism responsible for induction of cell radioresistance. This response triggered by irradiated cells could not be abrogated by different treatments like histamine or the

  14. Radiosensitization of hypoxic cells treated with some imidazole derivatives

    International Nuclear Information System (INIS)

    Extensive investigations to seek more effective and less toxic radiosensitizers to hypoxic cells than misonidazole were carried out. It has been considered that the neurotoxicity of misonidazole was mainly due to the nitro substituent which is bounded to the imidazole ring. Instead of the nitro group, many types of sulfur group were introduced to the imidazole ring. Usually the radiosensitizing ability of the compound is supposed to be related to the electron affinity. Therefore, as an indicator of the electron affinity, the lowest unoccupied molecular orbital (LUMO) level of these compounds was determined by the MO calculation using the CNDO/2 method. The LUMO level of these compounds was almost the same as that of misonidazole. Expecting good radiosensitizing effect of these compounds, the radiation enhancement ratio to the hypoxic cells was tested in vitro. To get the hypoxic cells in vitro, HeLa S3 cells were flushed by 95% N2 + 5% CO2 gas in minimum essential medium. The oxygen enhancement ratio (OER) was measured at about 3 in this system. Unfortunately, the sulfur compounds have no radiosensitization to the hypoxic cells. Since the radiosensitizing ability seemed not directly to be related to the electron affinity and the radiosensitizing effect of misonidazole must be mainly due to the nitro substituent, certain dinitroimidazole derivatives (e.g. 2.4-dinitroimidazole-1-ethanol) were further studied for the screening test. It was found that this compound had a radiosensitizing effect on the hypoxic cells about ten times greater than misonidazole. The cytotoxicity of this compound was also investigated in our hypoxic system and it was found to have twice as much as misonidazole. Further investigation of this compound is necessary to apply animal experiments and clinical use. (author)

  15. Pharmacokinetics of hypoxic cell radiosensitizers: a review

    International Nuclear Information System (INIS)

    The comparative pharmacokinetics of various nitroimidazole radiosensitizers in different species are reviewed. Radiosensitization is dependent upon the tumor concentration at the time of radiotherapy, whereas host toxicity, including peripheral neuropathy, appears to be related to the tissue exposure or area under the curve (AUC). Nitroimidazoles penetrate lipoid membranes by passive diffusion, the rate increasing with lipophilicity. Derivatives more hydrophilic than misonidazole penetrate nervous tissues comparatively slowly. They are eliminated mainly by renal clearance. Most plasma data for intravenous radiosensitizers can be described by a two-compartment open model. But in the mouse, the kinetics of misonidazole are dose dependent with increasing apparent t1/2 and AUC at higher doses due to saturable Michaelis-Menten kinetics for metabolism

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

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    Ju, Yeun-Jin; Shin, Hyun-Jin; Park, Jeong-Eun; Juhn, Kyoung-Mi; Woo, Seon Rang; Kim, Hee-Young; Han, Young-Hoon; Hwang, Sang-Gu; Hong, Sung-Hee; Kang, Chang-Mo [Division of Radiation Cancer Research, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of); Yoo, Young-Do [Laboratory of Molecular Cell Biology, Graduate School of Medicine, Korea University College of Medicine, Korea University, Seoul 136-705 (Korea, Republic of); Park, Won-Bong [Division of Natural Science, Seoul Women' s University, Seoul 139-774 (Korea, Republic of); Cho, Myung-Haing [Laboratory of Toxicology, College of Veterinary Medicine, Seoul National University, Seoul (Korea, Republic of); Park, Gil Hong, E-mail: ghpark@korea.ac.kr [Department of Biochemistry, College of Medicine, Korea University, Seoul (Korea, Republic of); Lee, Kee-Ho, E-mail: khlee@kirams.re.kr [Division of Radiation Cancer Research, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of)

    2010-11-12

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

  17. Radiosensitization and radiation chemistry studies using CHO cells

    International Nuclear Information System (INIS)

    The cytotoxicity, radiosensitization and radiation chemistry studies on several recently synthesized isoindole-4,7-diones using chinese hamster ovary cells (CHO) have been carried out. The cytotoxicity studies have shown that these quinones have cytotoxic activity under oxic and hypoxic conditions. Radiosensitization studies using a Cs-137 irradiator at different radiation doses demonstrate that these isoindole-diones have radiosensitization characteristics under hypoxic conditions. The results are compared with the well known radiosensitizer, misoidazole, under the same conditions. The electron redox potential of these quinones are in the vicinity of -440mv to -360mv, which demonstrates that they have the appropriate electron affinity to transfer electrons quite readily. The interaction of glutathione, a well known radioprotector, with these quinones was also studied. The concentration of glutathione in CHO cells decreases very little in the presence of the isoindole-diones. The results of these experiments show that the radiosensitization mechanism of these isoindole-diones is mainly due to electron transfer reactions and not to interaction with chemical radioprotectors such as glutathione in the CHO cells

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

    International Nuclear Information System (INIS)

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

  19. Effect of salt solutions on the radiosensitivity of mammalian cells

    International Nuclear Information System (INIS)

    The effects of a wide concentration range of NaCl solutions containing either ouabain, ethanol, para-nitroacetophenone (PNAP), N-ethylmaleimide (NEM), cysteamine or dimethyl sulphoxide (DMSO) on cellular radiosensitivity have been examined. Ouabain and NEM treatment increased the radiosensitivity of V79 Chinese hamster cells, but the action of these chemicals did not depend on the concentration of NaCl. PNAP increased cellular radiosensitivity with increasing NaCl concentration reaching a maximum effect at 0.6 to 0.7 M NaCl. The radioprotective properties of cysteamine, DMSO and ethanol were all strongly dependent on the NaCl concentration in a complex but qualitatively similar manner. DMSO (2.0 M) increased survival of cells after a 1380 rad dose by a factor of about 104 when present in 0.075 NaCl and by a factor of 8.7 when present in 1.2 M NaCl. (author)

  20. Radiosensitization of EMT6 cells by four platinum complexes.

    Science.gov (United States)

    Teicher, B A; Rockwell, S; Lee, J B

    1985-05-01

    The greatest research effort in producing radiation sensitizers has been directed toward organic compounds. However, platinum complexes also have radiosensitizing capabilities, perhaps because they bind to DNA. The compound described here are dichloro complexes of bivalent platinum with one or two potentially radiosensitizing ligands. The radiosensitization of oxygenated and hypoxic exponentially growing EMT6 cells in vitro was measured. The dose modifying factors obtained with 200 microM and 400 microM trans-bis(2-nitroimidazole)dichloroplatinum II (NIPt) in hypoxic cells were 1.5 and 2.1, respectively. For trans-bis(2-amino-5-nitrothiazole)dichloroplatinum II (Plant) under the same conditions, the dose modifying factor was 1.5 at 200 microM and 1.8 at 400 microM. Neither compound sensitized oxygenated cells when tested similar protocols. Unlike the trans complexes, (1,2-diamino-4-nitrobenzene)dichloroplatinum II (Plato) was cytotoxic toward the hypoxic cells in the absence of X rays. The time course of cytotoxicity for 100 microM Plato in exponentially growing cells showed rapid killing of hypoxic cells, and much less toxicity toward oxygenated cells. In radiosensitization studies, dose modifying factors of 1.6 and 2.0 were found with 200 microM and 400 microM Plato in hypoxic cells. The compound did not sensitize aerobic cells. The well-known platinum complex cis-dipyridinedichloroplatinum II (PyPt) represents a cis-platinum heterocyclic aromatic complex that does not have a nitro-functionality. The dose modifying factor obtained with 400 microM PyPt in hypoxic cells was 1.7. On a molar basis, the nitro-functional platinum complexes appear to be more effective as hypoxic cell radiosensitizers than the corresponding free ligands. PMID:4039304

  1. Anoxic-cell radiosensitization induced by heterocyclic compounds

    International Nuclear Information System (INIS)

    The anoxic cell compartment of in vivo solid tumors limits to some extent the effects of therapeutic radiation. The development of anoxic-cell radiosensitizers, as represented by the imidazole derivatives, has been given considerable attention. Hyperbaric oxygen was also considered for this purpose, Misonidazole, one of the imidazole derivatives, has a radiosensitization effect on anoxic cell killing. However, clinical application was not feasible because the drug proved to be toxic to the central nervous system. The extent of neurotoxicity of the imidazole derivatives correlates with the lipophilicity of the drugs. If the hydrophilicity of the drug could be increased to the extent that the toxicity to the central nervous system would be diminished, then the effect of anoxic-cell radiosensitization of the drug in unit drug amount/body weight or body surface could be maintained. The authors assayed a series of compounds, o-, m-, and p-nitrophenyl-tatrazoles, for their possible anoxic-cell radiosensitization effects. The differential effects were observed among the three isomers by cell survival assays in colony formations of Chinese hamster V-79 strain of cells, in vitro

  2. Radiosensitizing Effect of TRPV1 Channel Inhibitors in Cancer Cells.

    Science.gov (United States)

    Nishino, Keisuke; Tanamachi, Keisuke; Nakanishi, Yuto; Ide, Shunta; Kojima, Shuji; Tanuma, Sei-Ichi; Tsukimoto, Mitsutoshi

    2016-07-01

    Radiosensitizers are used in cancer therapy to increase the γ-irradiation susceptibility of cancer cells, including radioresistant hypoxic cancer cells within solid tumors, so that radiotherapy can be applied at doses sufficiently low to minimize damage to adjacent normal tissues. Radiation-induced DNA damage is repaired by multiple repair systems, and therefore these systems are potential targets for radiosensitizers. We recently reported that the transient receptor potential vanilloid type 1 (TRPV1) channel is involved in early responses to DNA damage after γ-irradiation of human lung adenocarcinoma A549 cells. Therefore, we hypothesized that TRPV1 channel inhibitors would have a radiosensitizing effect by blocking repair of radiation-induced cell damage. Here, we show that pretreatment of A549 cells with the TRPV1 channel inhibitors capsazepine, AMG9810, SB366791 and BCTC suppressed the γ-ray-induced activation of early DNA damage responses, i.e., activation of the protein kinase ataxia-telangiectasia mutated (ATM) and accumulation of p53-binding protein 1 (53BP1). Further, the decrease of survival fraction at one week after γ-irradiation (2.0 Gy) was enhanced by pretreatment of cells with these inhibitors. On the other hand, inhibitor pretreatment did not affect cell viability, the number of apoptotic or necrotic cells, or DNA synthesis at 24 h after irradiation. These results suggest that inhibition of DNA repair by TRPV1 channel inhibitors in irradiated A549 cells caused gradual loss of proliferative ability, rather than acute facilitation of apoptosis or necrosis. TRPV1 channel inhibitors could be novel candidates for radiosensitizers to improve the efficacy of radiation therapy, either alone or in combination with other types of radiosensitizers. PMID:27150432

  3. Neoadjuvant immunotherapy enhances radiosensitivity through natural killer cell activation.

    Science.gov (United States)

    Chi, Chau-Hwa; Wang, Yu-Shan; Yang, Chieh-Han; Chi, Kwan-Hwa

    2010-02-01

    We investigated whether natural killer (NK) cells in the tumor microenvironment have a radiosensitization effect. The radiosensitization effect of combined CpG and Herceptin((R)) (Genentech, Inc., South San Francisco, CA) (CpG/Herceptin), given before or after radiation, was evaluated by using a murine colon cancer cell line overexpressing human HER2/neu, CT26HER2/neu. In vitro radiosensitization effects were investigated by coculture of CT26HER2/neu with splenocytes, CpG, and Herceptin before applying radiation. Tumor cells, cocultured with CpG-pretreated splenocytes and Herceptin, were more vulnerable to radiation damage. In BALB/c mice injected with CT26HER2/neu, CpG/Herceptin administered before radiotherapy was associated with a better retardation of tumor growth than when administered after radiotherapy. The radiosensitization effect was significantly abrogated by NK-cell depletion, indicating that NK cells play an essential role in it. Further, surviving mice treated with CpG or CpG/Herceptin and reverse transcriptase were resistant to renewed tumor challenge, suggesting the presence of an induced immune response to the tumor. Neoadjuvant immunotherapy with CpG/Herceptin may improve response to radiotherapy of HER2/neu-expressing tumors. PMID:20187795

  4. Radiosensitization by cisplatin of RIF1 tumour cells in vitro

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    Begg, A.C.; Kolk, P.J. van der; Dewit, L.; Bartelink, H.

    1986-11-01

    The ability of cis-diamminedichloroplatinum (II) (c-DDP) to enhance radiation-induced cell killing was tested on oxic RIF1 tumour cells in monolayer culture. Marked radiosensitization of the survivors of a 1 h drug treatment was found with all c-DDP doses tested, enhancement ratios increasing from 1.2 to 2.2 with increasing drug dose. Isobologram analyses showed that the interactions of c-DDP with X-rays were supra-additive. To test whether part of the enhancement was due to a selection of subpopulations, the diploid and tetraploid RIF1 cells, normally coexisting in culture, were separated by (a) unit gravity velocity sedimentation, and (b) by developing diploid and tetraploid clones. Both methods showed little difference in either drug sensitivity or radiation sensitivity between diploid and tetraploid cells. DNA histograms obtained by flow cytometry showed little or no cycle progression during the 1 h drug treatment. These data indicate that the radiosensitization was not the result of the drug exposure leaving cells in a radiosensitive phase. The observed radiosensitization, therefore, appears to have resulted from a true drug/X-ray interaction.

  5. Radiosensitizing effect of RHOB protein in melanoma cells

    International Nuclear Information System (INIS)

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

  6. Radiosensitization of EMT6 cells by four platinum complexes

    Energy Technology Data Exchange (ETDEWEB)

    Teicher, B.A.; Rockwell, S.; Lee, J.B.

    1985-05-01

    The compounds described here are dichloro complexes of bivalent platinum with one or two potentially radiosensitizing ligands. The radiosensitization of oxygenated and hypoxic exponentially growing EMT6 cells in vitro was measured. The dose modifying factors obtained with 200 ..mu..M and 400 ..mu..M trans-bis(2-nitroimidazole)dichloroplatinum II (NIPt) in hypoxic cells were 1.5 and 2.1, respectively. For trans-bis(2-amino-5-nitrothiazole)dichloroplatinum II (Plant) under the same conditions, the dose modifying factor was 1.5 at 200 ..mu..M and 1.8 at 400 ..mu..M. Neither compound sensitized oxygenated cells when tested similar protocols. Unlike the trans complexes (1,2-diamino-4-nitrobenzene)dichloroplatinum II (Plato) was cytotoxic toward the hypoxic cells in the absence of X rays. The time course of cytotoxicity for 100 ..mu..M Plato in exponentially growing cells showed rapid killing of hypoxic cells, and much less toxicity toward oxygenated cells. In radiosensitization studies, dose modifying factors of 1.6 and 2.0 were found with 200 ..mu..M and 400 ..mu..M Plato in hypoxic cells. The compound did not sensitize aerobic cells. The well-known platinum complex cis-dipyridinedichloroplatinum II (PyPt) represents a cis-platinum heterocyclic aromatic complex that does not have a nitro-functionality. The dose modifying factor obtained with 400 ..mu..M PyPt in hypoxic cells was 1.7. On a molar basis, the nitro-functional platinum complexes appear to be more effective as hypoxic cell radiosensitizers than the corresponding free ligands.

  7. Radiosensitization of EMT6 cells by four platinum complexes

    International Nuclear Information System (INIS)

    The compounds described here are dichloro complexes of bivalent platinum with one or two potentially radiosensitizing ligands. The radiosensitization of oxygenated and hypoxic exponentially growing EMT6 cells in vitro was measured. The dose modifying factors obtained with 200 μM and 400 μM trans-bis(2-nitroimidazole)dichloroplatinum II (NIPt) in hypoxic cells were 1.5 and 2.1, respectively. For trans-bis(2-amino-5-nitrothiazole)dichloroplatinum II (Plant) under the same conditions, the dose modifying factor was 1.5 at 200 μM and 1.8 at 400 μM. Neither compound sensitized oxygenated cells when tested similar protocols. Unlike the trans complexes (1,2-diamino-4-nitrobenzene)dichloroplatinum II (Plato) was cytotoxic toward the hypoxic cells in the absence of X rays. The time course of cytotoxicity for 100 μM Plato in exponentially growing cells showed rapid killing of hypoxic cells, and much less toxicity toward oxygenated cells. In radiosensitization studies, dose modifying factors of 1.6 and 2.0 were found with 200 μM and 400 μM Plato in hypoxic cells. The compound did not sensitize aerobic cells. The well-known platinum complex cis-dipyridinedichloroplatinum II (PyPt) represents a cis-platinum heterocyclic aromatic complex that does not have a nitro-functionality. The dose modifying factor obtained with 400 μM PyPt in hypoxic cells was 1.7. On a molar basis, the nitro-functional platinum complexes appear to be more effective as hypoxic cell radiosensitizers than the corresponding free ligands

  8. Growth and radiosensitivity of irradiated human glioma cell progeny

    Institute of Scientific and Technical Information of China (English)

    Chao Li; Li Li; Changshao Xu; Juying Zhou

    2008-01-01

    BACKGROUND: Progenitors of the immortalized human glioma cell line, SHG-44, are significantly less sensitive to irradiation. Two hypotheses regarding the mechanism of this effect exist: several studies have suggested that there is a subgroup with different radiosensitivities in identical cell group, and the progenitors of irradiate is a adaptive response subgroup, so its radiosensitivity is descend. A second hypothesis suggests that irradiated glioma progeny have a stronger ability to repair DNA damage. This would suggest that when progeny are continuously irradiated, resistance to irradiation-induced DNA increases, and radiosensitivity decreases.OBJECTIVE: To investigate radiosensitivity and growth features after irradiation to progeny of the human glioma cell line SHG-44.DESIGN, TIME AND SETTING: A randomized, controlled experiment, which was performed at the Department of Radiology Laboratory, the First Hospital Affiliated to Soochow University, between September 2004 and January 2006.MATERIALS: The glioma cell line SHG-44 was provided by the Institute of Neuroscience, First Affiliated Hospital of Suzhou University. Propidium iodide reagent was provided by Coulter Corporation. A linear accelerator, KD-2 type, was provided by Siemens, Germany. The flow cytometer EPICS-XL was provided by Coulter Corporation.METHODS: Brain glioma SHG-44 cells were divided into four groups: SHG-44, SHG-44-2, SHG-44-6, and SHG-44-10. The SHG-44-2, SHG-44-6, and SHG-44-10 cells were vertically irradiated with varying doses of 2,6 and 10 Gy by a linear accelerator (6 MVX). The cells were passaged for 15 generations and cultured in RPMI-1640 culture media.MAIN OUTCOME MEASURES: Community re-double time, mean lethal dose (D0), extrapolation number (N), fraction surviving fraction irradiated by 2 Gy dose (SF2), quasi-threshold dose (Dq), and cell cycle.RESULTS: The Population doubling time (PDT) of SHG-44-2, SHG-44-6, and SHG-44-10 cell groups was not significant (P=0.052). Compared to

  9. [Cisplatin influence on: the radiosensitivity and recovery of yeast cells].

    Science.gov (United States)

    2013-01-01

    The effect of the simultaneous combined action of ionizing radiation and cisplatin on the radiosensitivity and liquid holding recovery (LHR) of diploid yeast cells was studied. It was shown that regardless of the cisplatin concentration (0; 0.002; 0.01; 0.02 g/ml) the radiosensitivity of cells was increased by 1.3 times. The ability of a cell to the LHR was progressively decreased with the increasing cisplatin concentration up to the complete inhibition. It was shown that the LHR of yeast cells after a combined action of ionizing radiation and chemical agents is mainly inhibited due to formation of a greater proportion of irreversible damage. The con- stant of recovery, characterizing the probability of recovery per a unit of time, was independent on cisplatine concentration. PMID:25508873

  10. On the role of ploidy in cell radiosensitivity

    International Nuclear Information System (INIS)

    Sensitivity of experimentally obtained diploid cells of naturally occuring haplonts Pichia pinus and Pichia quilliermondii to gamma-quanta and α-particles has been shown to be twice as high as that of haploid cells and, therefore, independent of the ploidy, as calculated per one set of chromosomes. In this respect, the haplonts under study are similar to diplonts Saccharomyces cerevisiae, carrying rad 51 mutation, and drastically different from Saccharomyces cerevisiae of ''wild type'' whose haploid cells are much more radiosensitive than diploids. It has also been found that relative biological effectiveness (RBE) of α-particles for yeasts of the strains under study decreases, with increasing radiosensitivity, varying from 4.6 to 1.0. It is concluded that: (1) similar lesions lay the basis of radiation damage to both haploid and diploid yeast cells; the probability of formation of these lesions is conditioned by the dimensions of the ''target'' (DNA content) and the effectiveness of the repair systems, (2) the presence in the cell of at least two sets of chromosomes is necessary for productive work of the repair systems, (3) a higher radioresistance of diploid cells as compared to haploids in diplonts is mainly due to the effective work of the repair systems, (4) a higher radiosensitivity of diploid cells as compared to haploids in haplonts is perhaps due to a deficiency of these yeasts in repair systems, (5) an important role is ascribed to repair processes in the estimation of RBE of radiations possessing different LET

  11. The HSP90 Inhibitor Ganetespib Radiosensitizes Human Lung Adenocarcinoma Cells

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Casal, Roberto; Bhattacharya, Chitralekha [The University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213 (United States); Department of Medicine, The University of Pittsburgh, Pittsburgh, PA 15213 (United States); Epperly, Michael W. [The University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213 (United States); Department of Radiation Oncology, The University of Pittsburgh, Pittsburgh, PA 15213 (United States); Basse, Per H. [The University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213 (United States); Department of Immunology, The University of Pittsburgh, Pittsburgh, PA 15213 (United States); Wang, Hong [The University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213 (United States); Department of Biostatistics, The University of Pittsburgh, Pittsburgh, PA 15213 (United States); Wang, Xinhui [Harvard Medical School, Harvard University, 25 Shattuck Street, Boston, MA 02115 (United States); Proia, David A. [Synta Pharmaceuticals Corp., 45 Hartwell Avenue, Lexington, MA 02421 (United States); Greenberger, Joel S. [The University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213 (United States); Department of Radiation Oncology, The University of Pittsburgh, Pittsburgh, PA 15213 (United States); Socinski, Mark A.; Levina, Vera, E-mail: levinav@upmc.edu [The University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213 (United States); Department of Medicine, The University of Pittsburgh, Pittsburgh, PA 15213 (United States)

    2015-05-22

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

  12. The HSP90 Inhibitor Ganetespib Radiosensitizes Human Lung Adenocarcinoma Cells

    International Nuclear Information System (INIS)

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

  13. Radiosensitivity of CD3-CD8+CD56+ NK cells

    Energy Technology Data Exchange (ETDEWEB)

    Vokurkova, Doris [Charles University in Prague, Faculty of Medicine in Hradec Kralove, Department of Medical Biochemistry, Simkova 870, 50038 Hradec Kralove 1 (Czech Republic); Vavrova, Jirina [University of Defence, Faculty of Military Health Sciences, Department of Radiobiology, Hradec Kralove (Czech Republic); Sinkora, Jiri [Becton Dickinson (Czech Republic); Stoklasova, Alena [Charles University in Prague, Faculty of Medicine in Hradec Kralove, Department of Medical Biochemistry, Simkova 870, 50038 Hradec Kralove 1 (Czech Republic); Blaha, Vaclav [University of Defence, Faculty of Military Health Sciences, Department of Radiobiology, Hradec Kralove (Czech Republic); Rezacova, Martina, E-mail: rezacovam@lfhk.cuni.c [Charles University in Prague, Faculty of Medicine in Hradec Kralove, Department of Medical Biochemistry, Simkova 870, 50038 Hradec Kralove 1 (Czech Republic)

    2010-10-15

    The effect of lower doses (0.5-3.0 Gy) of gamma radiation on radiosensitivity of CD3-/CD8+ NK cells subpopulation isolated from the peripheral blood of healthy volunteers was studied 48 h after the irradiation. Only a subtle increase in terms of induction of apoptosis (A+ cells), was observed in Annexin positive CD3-/CD8+ NK cells. The assessment of the relative presence of CD3{sup -}/CD8{sup +} NK cells in Annexin negative populations of lymphocytes considerably contributes to the elimination of individual variability and could be useful in biodosimetry. Living CD3-/CD8+; Annexin negative NK cells were analyzed using five-color flow cytometry 16 h after irradiation by the doses of 1-10 Gy. The study was carried out on NK cells subsets CD3-/CD8- CD16+, CD56 (dim) and CD56 (bright). NK cells characterized with their low-density expression of CD56 (dim) are more cytotoxic and express CD16. Those with high-density expression of CD56 (bright) are known for their capacity to produce cytokines following activation of monocytes but their natural cytotoxicity is low; they are classified as CD16- or CD16 (dim). A dose-depending decrease in the relative presence of CD3-/CD8+ NK cells was observed 16 h after ionizing radiation (1-10 Gy). The decrease was highly pronounced in CD56 (bright) subset of NK cells and this subpopulation was considered as the most radiosensitive one. Unfortunately, the most radiosensitive subpopulation of NK cells - CD56bright cannot be used as a biodosimetric marker due to its insufficient amount in peripheral blood.

  14. Histamine as a Radiosensitizer of Malignant Cell Lines

    International Nuclear Information System (INIS)

    It has been established that the treatment with Histamine (Hi) produces a significant growth inhibition of different cell lines derived from human neoplasia. In a model of Knockout mice completely depleted of endogenous Hi, it was observed a significant delay in bone marroe repopulation after whole body irradiation. These results are in agreement with the hypothesis that histamine has a role in the regulation of haematopoiesis as well as an inhibitory effect on apoptosis. The objective of this paper was to study the possible effect of Hi as protector of normal cells and radiosensitizer of malignant ones. To study the effect of Hi on small-intestine and bone marrow, thirty made mice were randomly separeted into two groups: Control irradiated (C), and irradiated receiving Histamine (HI-group). All animals received a single dose of 10 Gy on whole-body employing a ''137Cs source of 189 TBq (Dose rate: 7.7 Gy/min) calibrated with TLD 700 dosimeter. Hi-group recieved a daily se injection (0.1 mg/kg) starting 20 hs before irradiation. Mice were sacrificed 5 days after irradiation. Histopathological analysis indicated that intestinal mucosae of C group showed important injury, whist mucosae of Hi-treated mice showed mild mucosal atrophy with conservation of villous projections and absence of vascular congestive changes. In order to investigate the effect of Hi on radiosensitivity of transformed cells, MDA-MB-231 (human breast carcinoma cells) were irradiated in vitro with doses ranging from 0 to 10 Gy. Results of radiobiological parameters indicate a significant increase on radiosensitivity of malignant cells. Employing specific fluorescent dyes and flow cytometric analysis we determined that the intracellular levels of hydrogen peroxide (H2O2) are significant increased by Hi 10 μM in control and also in irradiated MDA-MB-231 cells, while the levels of superoxide (SO2) were not significantly modified by Hi-treatment. (Author) 9 refs

  15. In vitro radiosensitivity of human leukemia cell lines

    International Nuclear Information System (INIS)

    The in vitro radiobiologic survival values (n, D0) of four tumor lines derived from human hematopoietic tumors were studied. These cell lines were HL50 (n . 1.3, D0 . 117 rad[1.17 Gy]), promyelocytic leukemia; K562 (n . 1.4, D0 . 165 rad[1.65 Gy]), erythroleukemia; 45 (n . 1.1, D0 . 147 rad[1.47 Gy]), acute lymphocyte leukemia; and 176 (n . 4.0, D0 . 76 rad[0.76 Gy]), acute monomyelogenous leukemia. More cell lines must be examined before the exact relationship between in vitro radiosensitivity and clinical radiocurability is firmly established

  16. Comparative radiosensitivity of Medfly cells and embryos.

    OpenAIRE

    Cavalloro, R.; Muñiz, M; Pozzi, G

    1984-01-01

    This research is dealing with the effect of 6O Co gamma radiation on cultured "In vitro" cells and on embryos at different developmental stages, of Ceratitis capitata Wiedemann. The parameters ana1yzed for both the cells and the embryos were growrh, survival and mortality rates. The immediate and late effects of irradiation were also studied at the level of egg hatching, larval life cycle, emergence of adults and their fertility. A particular result that became evident in the cormparison of t...

  17. Biogenic amines and radiosensitivity of solitary cells

    International Nuclear Information System (INIS)

    Different stability of cells to ionizing radiation is considered from a position of the ''elevated biochemical radioresistance background'' concept. Experimental evidence presented indicates an important role of endogenic amines (serotonin and histamine) possessing radioprotector properties in the cell radioresistance formation. The concept about their effect as being solely a result of circulatory hypoxia is critically discussed. The experimental results favor the existence of a ''cellular'' component, along with the ''hypoxic'' one, in the mechanism of action of biogenic amines. These compounds can affect the initial stages of peroxide oxidation of lipids, thereby favoring a less intensive oxidation induced by radiation. Biogenic amines can also exert influence on the cyclic nucleotide system

  18. NLP-1: a DNA intercalating hypoxic cell radiosensitizer and cytotoxin

    International Nuclear Information System (INIS)

    The 2-nitroimidazole linked phenanthridine, NLP-1 (5-[3-(2-nitro-1-imidazoyl)-propyl]-phenanthridinium bromide), was synthesized with the rationale of targeting the nitroimidazole to DNA via the phenanthridine ring. The drug is soluble in aqueous solution (greater than 25 mM) and stable at room temperature. It binds to DNA with a binding constant 1/30 that of ethidium bromide. At a concentration of 0.5 mM, NLP-1 is 8 times more toxic to hypoxic than aerobic cells at 37 degrees C. This concentration is 40 times less than the concentration of misonidazole, a non-intercalating 2-nitroimidazole, required for the same degree of hypoxic cell toxicity. The toxicity of NLP-1 is reduced at least 10-fold at 0 degrees C. Its ability to radiosensitize hypoxic cells is similar to misonidazole at 0 degrees C. Thus the putative targeting of the 2-nitroimidazole, NLP-1, to DNA, via its phenanthridine group, enhances its hypoxic toxicity, but not its radiosensitizing ability under the present test conditions. NLP-1 represents a lead compound for intercalating 2-nitroimidazoles with selective toxicity for hypoxic cells

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

    International Nuclear Information System (INIS)

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

  20. Ethanol decreases radiosensitivity of human breast cancer MCF-7 cells

    International Nuclear Information System (INIS)

    Objective: To investigate the effect of ethanol on radiosensitivity of human breast cancer MCF-7 cells. Methods: Human breast cancer MCF-7 cells were divided into four groups including control group,ethanol treatment group, X-ray exposed group,and ethanol combined with X-ray group. Clonogenic assay was used to determine cell survival. Flow cytometry was employed to analyze cell cycle progression. Annexin V-FITC kit was used to determine cell apoptosis induction.Results Ethanol (50 and 100 mmol/L, 50 h) had no influence on MCF-7 cell growth (t=0.82, 1.15, P>0.05). The radiosensitivity of MCF-7 cells was reduced when the cells were pretreated with 50 mmol/L ethanol (t=4.15, P<0.05) and 100 mmol/L ethanol (t=10.28, P<0.05) for 2 h. Compared with irradiation with X-ray alone, ethanol treatment decreased G2/M phase arrest (t=7.18, P<0.05) and sub-G1 population (an indicator of apoptosis induction) (t=5.39, P<0.05). A decrease of advanced and early apoptosis in the cells pretreated with ethanol was also confirmed by Annexin V-FITC apoptosis assay (t=4.86, 7.59, P<0.05). Conclusions: Ethanol causes radioresistance in human breast cancer MCF-7 cells, where the decreases of radiation-induced G2/M phase arrest and apoptosis may be involved. (authors)

  1. Radiosensitization by Inhibiting STAT1 in Renal Cell Carcinoma

    International Nuclear Information System (INIS)

    Purpose: Renal cell carcinoma (RCC) has been historically regarded as a radioresistant malignancy, but the molecular mechanism underlying its radioresistance is not understood. This study investigated the role of signal transducer and activator of transcription 1 (STAT1), a transcription factor downstream of the interferon-signaling pathway, in radioresistant RCC. Methods and Materials: The expressions of STAT1 and STAT3 in 164 human clear cell RCC samples, 47 papillary RCC samples, and 15 normal kidney tissue samples were examined by microarray expression profiling and immunohistochemistry. Western blotting was performed to evaluate the total and phosphorylated STAT1 expression in CRL-1932 (786-O) (human clear cell RCC), SKRC-39 (human papillary RCC), CCL-116 (human fibroblast), and CRL-1441 (G-401) (human Wilms tumor). STAT1 was reduced or inhibited by fludarabine and siRNA, respectively, and the effects on radiation-induced cell death were investigated using clonogenic assays. Results: STAT1 expression, but not STAT3 expression, was significantly greater in human RCC samples (p = 1.5 x 10-8 for clear cell; and p = 3.6 x 10-4 for papillary). Similarly, the expression of STAT1 was relatively greater in the two RCC cell lines. STAT1 expression was reduced by both fludarabine and siRNA, significantly increasing the radiosensitivity in both RCC cell lines. Conclusion: This is the first study reporting the overexpression of STAT1 in human clear cell and papillary RCC tissues. Radiosensitization in RCC cell lines was observed by a reduction or inhibition of STAT1 signaling, using fludarabine or siRNA. Our data suggest that STAT1 may play a key role in RCC radioresistance and manipulation of this pathway may enhance the efficacy of radiotherapy

  2. Advances in radiation biology: Radiosensitization in DNA and living cells

    Science.gov (United States)

    Lacombe, S.; Sech, C. Le

    2009-06-01

    One fundamental goal of radiation biology is the evolution of concepts and methods for the elaboration of new approaches and protocols for the treatment of cancers. In this context, the use of fast ions as ionizing particles offers the advantage of optimizing cell killing inside the tumor whilst preserving the surrounding healthy tissues. One extremely promising strategy investigated recently is the addition of radiosensitizers in the targeted tissue. The optimization of radiotherapy with fast ions implies a multidisciplinary approach to ionizing radiation effects on complex living systems, ranging from studies on single molecules to investigations of entire organisms. In this article we review recent studies on ion induced damages in simple and complex biological systems, from DNA to living cells. The specific aspect of radiosensitization induced by metallic atoms is described. As a fundamental result, the addition of sensitizing compounds with ion irradiation may improve therapeutic index in cancer therapy. In conclusion, new perspectives are proposed based on the experience and contribution of different communities including Surface Sciences, to improve the development of radiation biology.

  3. Histamine as a Radiosensitizer of Malignant Cell Lines

    Energy Technology Data Exchange (ETDEWEB)

    Rivera, E. S.; Medina, V.; Cricco, G.; Mohamed, N.; Croci, M.; Martin, G.; Nunez, M.; Bergoc, R. M.

    2004-07-01

    It has been established that the treatment with Histamine (Hi) produces a significant growth inhibition of different cell lines derived from human neoplasia. In a model of Knockout mice completely depleted of endogenous Hi, it was observed a significant delay in bone marroe repopulation after whole body irradiation. These results are in agreement with the hypothesis that histamine has a role in the regulation of haematopoiesis as well as an inhibitory effect on apoptosis. The objective of this paper was to study the possible effect of Hi as protector of normal cells and radiosensitizer of malignant ones. To study the effect of Hi on small-intestine and bone marrow, thirty made mice were randomly separeted into two groups: Control irradiated (C), and irradiated receiving Histamine (HI-group). All animals received a single dose of 10 Gy on whole-body employing a ''137Cs source of 189 TB{sub q} (Dose rate: 7.7 Gy/min) calibrated with TLD 700 dosimeter. Hi-group recieved a daily se injection (0.1 mg/kg) starting 20 hs before irradiation. Mice were sacrificed 5 days after irradiation. Histopathological analysis indicated that intestinal mucosae of C group showed important injury, whist mucosae of Hi-treated mice showed mild mucosal atrophy with conservation of villous projections and absence of vascular congestive changes. In order to investigate the effect of Hi on radiosensitivity of transformed cells, MDA-MB-231 (human breast carcinoma cells) were irradiated in vitro with doses ranging from 0 to 10 Gy. Results of radiobiological parameters indicate a significant increase on radiosensitivity of malignant cells. Employing specific fluorescent dyes and flow cytometric analysis we determined that the intracellular levels of hydrogen peroxide (H{sub 2}O{sub 2}) are significant increased by Hi 10 {mu}M in control and also in irradiated MDA-MB-231 cells, while the levels of superoxide (SO{sub 2}) were not significantly modified by Hi-treatment. (Author) 9 refs.

  4. Radiosensitizing effect of epothilone B on human epithelial cancer cells

    International Nuclear Information System (INIS)

    A combined modality treatment employing radiation and chemotherapy plays a central role in the management of solid tumors. In our study, we examined the cytotoxic and radiosensitive effect of the microtubule stabilizer epothilone B on two human epithelial tumor cell lines in vitro and its influence on the microtubule assembly. Cancer cells were treated with epothilone B in proliferation assays and in combination with radiation in colony-forming assays. For the analysis of ionizing radiation-induced DNA damage and the influence of the drug on its repair a γH2AX foci assay was used. To determine the effect of epothilone B on the microtubule assembly in cells and on purified tubulin, immunofluorescence staining and tubulin polymerization assay, respectively, were conducted. Epothilone B induced a concentration- and application-dependent antiproliferative effect on the cells, with IC50 values in the low nanomolar range. Colony forming assays showed a synergistic radiosensitive effect on both cell lines which was dependent on incubation time and applied concentration of epothilone B. The γH2AX assays demonstrated that ionizing radiation combined with the drug resulted in a concentration-dependent increase in the number of double-strand breaks and suggested a reduction in DNA repair capacity. Epothilone B produced enhanced microtubule bundling and abnormal spindle formation as revealed by immunofluorescence microscopy and caused microtubule formation from purified tubulin. The results of this study showed that epothilone B displays cytotoxic antitumor activity at low nanomolar concentrations and also enhances the radiation response in the tumor cells tested; this may be induced by a reduced DNA repair capacity triggered by epothilone B. It was also demonstrated that epothilone B in fact targets microtubules in a more effective manner than paclitaxel. (orig.)

  5. Radiosensitizing effect of epothilone B on human epithelial cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Baumgart, T.; Kriesen, S.; Hildebrandt, G.; Manda, K. [Univ. of Rostock (Germany). Dept. of Radiotherapy and Radiation Oncology; Klautke, G.; Fietkau, R. [Friedrich-Alexander-Univ. Erlangen-Nuernberg, Erlangen (Germany). Dept. of Radiation Oncology; Kuznetsov, S.A.; Weiss, D.G. [Univ. of Rostock (Germany). Inst. of Biological Sciences, Cell Biology, and Biosystems Technology

    2012-02-15

    A combined modality treatment employing radiation and chemotherapy plays a central role in the management of solid tumors. In our study, we examined the cytotoxic and radiosensitive effect of the microtubule stabilizer epothilone B on two human epithelial tumor cell lines in vitro and its influence on the microtubule assembly. Cancer cells were treated with epothilone B in proliferation assays and in combination with radiation in colony-forming assays. For the analysis of ionizing radiation-induced DNA damage and the influence of the drug on its repair a {gamma}H2AX foci assay was used. To determine the effect of epothilone B on the microtubule assembly in cells and on purified tubulin, immunofluorescence staining and tubulin polymerization assay, respectively, were conducted. Epothilone B induced a concentration- and application-dependent antiproliferative effect on the cells, with IC{sub 50} values in the low nanomolar range. Colony forming assays showed a synergistic radiosensitive effect on both cell lines which was dependent on incubation time and applied concentration of epothilone B. The {gamma}H2AX assays demonstrated that ionizing radiation combined with the drug resulted in a concentration-dependent increase in the number of double-strand breaks and suggested a reduction in DNA repair capacity. Epothilone B produced enhanced microtubule bundling and abnormal spindle formation as revealed by immunofluorescence microscopy and caused microtubule formation from purified tubulin. The results of this study showed that epothilone B displays cytotoxic antitumor activity at low nanomolar concentrations and also enhances the radiation response in the tumor cells tested; this may be induced by a reduced DNA repair capacity triggered by epothilone B. It was also demonstrated that epothilone B in fact targets microtubules in a more effective manner than paclitaxel. (orig.)

  6. Radiosensitivity of human haematopoietic stem/progenitor cells

    International Nuclear Information System (INIS)

    The haematopoietic system is regenerative tissue with a high proliferative potential; therefore, haematopoietic stem cells (HSCs) are sensitive to extracellular oxidative stress caused by radiation and chemotherapeutic agents. An understanding of this issue can help predict haematopoietic recovery from radiation exposure as well as the extent of radiation damage to the haematopoietic system. In the present study, the radiosensitivity of human lineage-committed myeloid haematopoietic stem/progenitor cells (HSPCs), including colony-forming unit–granulocyte macrophage, burst-forming unit–erythroid and colony-forming unit–granulocyte–erythroid–macrophage–megakaryocyte cells, which are contained in adult individual peripheral blood (PB) and fetus/neonate placental/umbilical cord blood (CB), were studied. The PB of 59 healthy individual blood donors and the CB of 42 neonates were investigated in the present study. HSPCs prepared from PB and CB were exposed to 0.5 or 2 Gy x-irradiation. The results showed that large individual differences exist in the surviving fraction of cells. In the case of adult PB, a statistically significant negative correlation was observed between the surviving fraction observed at a dose of 0.5 Gy and the age of the blood donors; however, none of these correlations were observed after 2 Gy x-irradiation. In addition, seasonal and gender variation were observed in the surviving fraction of CB HSPCs. The present results suggest that there are large individual differences in the surviving fraction of HSPCs contained in both adult PB and fetus/neonate CB. In addition, some factors, including the gender, age and season of birth, affect the radiosensitivity of HSPCs, especially with a relatively low-dose exposure. (paper)

  7. Radiosensitivity of CD45RO+ memory and CD45RO- naive T cells in culture

    International Nuclear Information System (INIS)

    Radiosensitivities of various human T-cell subsets were investigated by a proliferation assay and by a single-cell gel electrophoresis assay. Each T-cell subset was purified using a cell sorter and was induced to proliferate by ionomycin and interleukin 2. Unsorted T cells showed biphasic dose-survival curves, indicating the heterogeneity of T cells in terms of radiosensitivity. Purified CD4+ helper and CD8+ killer T cells showed similar biphasic dose-survival curves. Hence both T-cell subsets were composed of cells of different radiosensitivity. The T-cell subsets belonging to different activation stages such as CD45RO+ memory and CD45RO- naive T cells had different dose-survival curves. The former was more radiosensitive than the latter. The high radiosensitivity of CD45RO+ cells was also demonstrated by single-cell gel electrophoresis after irradiation. This is the first demonstration that a particular cell surface marker on T cells is correlated with greater radiosensitivity. 27 refs., 7 figs., 1 tab

  8. Fulvestrant radiosensitizes human estrogen receptor-positive breast cancer cells

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    Wang, Jing, E-mail: wangstella5@163.com [Department of Breast Surgery, Qilu Hospital, Shandong Univeristy, Wenhua Xi Road 107, Shandong Province (China); Department of Oncology, Affiliated Hospital of Qingdao University Medical College, Shandong Province (China); Yang, Qifeng, E-mail: qifengy@gmail.com [Department of Breast Surgery, Qilu Hospital, Shandong Univeristy, Wenhua Xi Road 107, Shandong Province (China); Haffty, Bruce G., E-mail: hafftybg@umdnj.edu [Department of Radiation Oncology, UMDNJ-Robert Wood Johnson School of Medicine, Cancer Institute of New Jersey, NB (United States); Li, Xiaoyan, E-mail: xiaoyanli1219@gmail.com [Department of Oncology, Affiliated Hospital of Qingdao University Medical College, Shandong Province (China); Moran, Meena S., E-mail: meena.moran@yale.edu [Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT (United States)

    2013-02-08

    Highlights: ► Fulvestrant radiosensitizes MCF-7 cells. ► Fulvestrant increases G1 arrest and decreases S phase in MCF-7 cells. ► Fulvestrant down-regulates DNA-PKcs and RAD51 in MCF-7 cells. -- Abstract: The optimal sequencing for hormonal therapy and radiation are yet to be determined. We utilized fulvestrant, which is showing promise as an alternative to other agents in the clinical setting of hormonal therapy, to assess the cellular effects of concomitant anti-estrogen therapy (fulvestrant) with radiation (F + RT). This study was conducted to assess the effects of fulvestrant alone vs. F + RT on hormone-receptor positive breast cancer to determine if any positive or negative combined effects exist. The effects of F + RT on human breast cancer cells were assessed using MCF-7 clonogenic and tetrazolium salt colorimetric (MTT) assays. The assays were irradiated with a dose of 0, 2, 4, 6 Gy ± fulvestrant. The effects of F + RT vs. single adjuvant treatment alone on cell-cycle distribution were assessed using flow cytometry; relative expression of repair proteins (Ku70, Ku80, DNA-PKcs, Rad51) was assessed using Western Blot analysis. Cell growth for radiation alone vs. F + RT was 0.885 ± 0.013 vs. 0.622 ± 0.029 @2 Gy, 0.599 ± 0.045 vs. 0.475 ± 0.054 @4 Gy, and 0.472 ± 0.021 vs. 0.380 ± 0.018 @6 Gy RT (p = 0.003). While irradiation alone induced G2/M cell cycle arrest, the combination of F + RT induced cell redistribution in the G1 phase and produced a significant decrease in the proportion of cells in G2 phase arrest and in the S phase in breast cancer cells (p < 0.01). Furthermore, levels of repair proteins DNA-PKcs and Rad51 were significantly decreased in the cells treated with F + RT compared with irradiation alone. F + RT leads to a decrease in the surviving fraction, increased cell cycle arrest, down regulating of nonhomologous repair protein DNA-PKcs and homologous recombination repair protein RAD51. Thus, our findings suggest that F + RT

  9. Siah1 proteins enhance radiosensitivity of human breast cancer cells

    Directory of Open Access Journals (Sweden)

    Engenhart-Cabillic Rita

    2010-08-01

    Full Text Available Abstract Background Siah proteins play an important role in cancer progression. We evaluated the effect of Siah1, its splice variants Siah1L and the Siah1 mutant with the RING finger deleted (Siah1ΔR on radiosensitization of human breast cancer cells. Methods The status of Siah1 and Siah1L was analysed in five breast cancer cell lines. To establish stable cells, SKBR3 cells were transfected with Siah1, Siah-1L and Siah1ΔR. Siah1 function was suppressed by siRNA in MCF-7 cells. The impact of Siah1 overexpression and silencing on apoptosis, proliferation, survival, invasion ability and DNA repair was assessed in SKBR3 and MCF-7 cells, also in regards to radiation. Results Siah1 and Siah1L mRNA expression was absent in four of five breast cancer cells lines analysed. Overexpression of Siah1 and Siah1L enhanced radiation-induced apoptosis in stable transfected SKBR3 cells, while Siah1ΔR failed to show this effect. In addition, Siah1 and Siah1L significantly reduced cell clonogenic survival and proliferation. Siah1L sensitization enhancement ratio values were over 1.5 and 4.0 for clonogenic survival and proliferation, respectively, pointing to a highly cooperative and potentially synergistic fashion with radiation. Siah1 or Siah1L significantly reduced invasion ability of SKBR3 and suppressed Tcf/Lef factor activity. Importantly, Siah1 siRNA demonstrated opposite effects in MCF-7 cells. Siah1 and Siah1L overexpression resulted in inhibition of DNA repair as inferred by increased levels of DNA double-strand breaks in irradiated SKBR3 cells. Conclusion Our results reveal for the first time how overexpression of Siah1L and Siah1 can determine radiosensitivity of breast cancer cells. These findings suggest that development of drugs augmenting Siah1 and Siah1L activity could be a novel approach in improving tumor cell kill.

  10. Fulvestrant radiosensitizes human estrogen receptor-positive breast cancer cells

    International Nuclear Information System (INIS)

    Highlights: ► Fulvestrant radiosensitizes MCF-7 cells. ► Fulvestrant increases G1 arrest and decreases S phase in MCF-7 cells. ► Fulvestrant down-regulates DNA-PKcs and RAD51 in MCF-7 cells. -- Abstract: The optimal sequencing for hormonal therapy and radiation are yet to be determined. We utilized fulvestrant, which is showing promise as an alternative to other agents in the clinical setting of hormonal therapy, to assess the cellular effects of concomitant anti-estrogen therapy (fulvestrant) with radiation (F + RT). This study was conducted to assess the effects of fulvestrant alone vs. F + RT on hormone-receptor positive breast cancer to determine if any positive or negative combined effects exist. The effects of F + RT on human breast cancer cells were assessed using MCF-7 clonogenic and tetrazolium salt colorimetric (MTT) assays. The assays were irradiated with a dose of 0, 2, 4, 6 Gy ± fulvestrant. The effects of F + RT vs. single adjuvant treatment alone on cell-cycle distribution were assessed using flow cytometry; relative expression of repair proteins (Ku70, Ku80, DNA-PKcs, Rad51) was assessed using Western Blot analysis. Cell growth for radiation alone vs. F + RT was 0.885 ± 0.013 vs. 0.622 ± 0.029 @2 Gy, 0.599 ± 0.045 vs. 0.475 ± 0.054 @4 Gy, and 0.472 ± 0.021 vs. 0.380 ± 0.018 @6 Gy RT (p = 0.003). While irradiation alone induced G2/M cell cycle arrest, the combination of F + RT induced cell redistribution in the G1 phase and produced a significant decrease in the proportion of cells in G2 phase arrest and in the S phase in breast cancer cells (p < 0.01). Furthermore, levels of repair proteins DNA-PKcs and Rad51 were significantly decreased in the cells treated with F + RT compared with irradiation alone. F + RT leads to a decrease in the surviving fraction, increased cell cycle arrest, down regulating of nonhomologous repair protein DNA-PKcs and homologous recombination repair protein RAD51. Thus, our findings suggest that F + RT

  11. Evaluation of nitroimidazole hypoxic cell radiosensitizers in a human tumor cell line high in intracellular glutathione

    International Nuclear Information System (INIS)

    Five nitroimidazole hypoxic cell radiosensitizers were evaluated in a human lung adenocarcinoma cell line (A549) whose GSH level was 8-fold higher than Chinese hamster V79 cells. One millimolar concentrations of Misonidazole (MISO), SR-2508, RSU-1164, RSU-1172, and Ro-03-8799 sensitized hypoxic A549 cells to radiation, with Ro-03-8799 giving the highest sensitizer enhancement ration (SER) (2.3). However, MISO, SR-2508 and Ro-03-8799 were less effective in this cell line than in V79 cells, presumably due to higher GSH content of the A549 cells. Increased hypoxic radiosensitization was seen with 0.1 mM Ro-03-8799 after GSH depletion by BSO as compared to 0.1 mM Ro-03-8799 alone (SER-1.8 vs 1.3). The combination of GSH depletion and 0.1 mM Ro-03-8799 was considerably more toxic than 0.1 mM or 1.0 mM Ro-03-8799 alone. This sensitivity was much greater than has been observed for SR-2508. These data show that Ro-03-8799 was the most efficient hypoxic cell radiosensitizer in a human tumor cell line considerably higher in GSH than the rodent cell lines often used in hypoxic radiosensitization studies. Thus, Ro-03-8799 may be a more effective hypoxic cell sensitizer in human tumors that are high in GSH

  12. Cell cycle effects for radiosensitivity after heavy ion exposure

    International Nuclear Information System (INIS)

    In order to study the relative contribution of the two major DNA double-strand break (DSB) repair pathways, non-homologous end-joining (NHEJ) and homologous recombinational repair (HRR), to the repair of DSBs and non-DSB clustered DNA damage induced by high linear energy transfer (LET) ionizing radiation through the cell cycle, we exposed wild type (WT), NHEJ-deficient, and HRR-deficient Chinese hamster ovary (CHO) cells synchronized by mitotic shake-off to accelerated heavy ions and X-rays. The cell cycle-dependent variation in survival observed in WT cells after X-irradiation was not observed after exposure to 500 MeV/amu iron ions. Non-homologous end joining (NHEJ) and homologous recombinational repair (HRR)-defective cells showed different patterns of cell cycle-dependent radiosensitivity after X-irradiation compared to WT cells, that were likewise significantly attenuated after iron ion exposures. Higher relative biological effectiveness for several other accelerated heavy ions (C, Ne, Si, Ar) of differing LETs was observed for cells exposed in S phase compared to cells exposed in G1. We also observed that HRR deficiency, unlike NHEJ deficiency, did not affect the progression of irradiated G2 cells into mitosis, thus contributing to increased cell killing observed in G2-phase HRR-deficient cells. The HRR-deficient cells showed significantly increased levels of chromatid-type aberrations that correlated with their cell cycle pattern of survival after both X- and iron ion irradiation. Our results suggest that high LET radiation produces not only complex DSBs but also complex non-DSB clustered lesions that specifically require the HRR-mediated repair of these lesions if encountered during DNA replication. In this year, we focused on Fanconi Anemia DNA repair pathway. Only FancA mutant cells showed hypersensitivity to high LET ionizing radiation among other FancC, FancD1, FancD2, and FancG mutant cells. (author)

  13. Radiosensitization of mouse L cells by an electron affinic radiosensitizer, Ro-07-0582 under an extremely hypoxic condition

    International Nuclear Information System (INIS)

    The present investigation was undertaken with the hope for elucidating the effect of a radiosensitizer on mouse L cells in culture following x-irradiation. Under the aerobic condition, a survival curve of irradiated cells showed a shoulder region with the extrapolation number of 6.4 and mean lethal dose (D0 value) of 126 rad. On the other hand, under the extremely hypoxic condition prepared with nitrogen gas using a stainless steel apparatus, a survival curve was found to show no shoulder region, having extrapolation number of 1.1 and D0 value of 629 rad. Thus, the oxygen enhancement ratio (o. e. r.) was calculated as a factor 5. An electron affinic radiosensitizer, Ro-07-0582 revealed a pronounced sensitizing effect under the extremely hypoxic condition by an enhancement ratio 3.9 at a concentration of 10 mM. The sensitizer reduced D0 value with increasing concentration of the drug. The evidence obtained suggests that Ro-07-0582 acts as oxygen-mimic, although the drug shows no radiosensitizing effect at low concentration and low irradiation doses. (author)

  14. Glutathione depletion, radiosensitization, and misonidazole potentiation in hypoxic Chinese hamster ovary cells by buthionine sulfoximine

    International Nuclear Information System (INIS)

    Buthionine sulfoximine (BSO) inhibits the synthesis of glutathione (GSH), the major nonprotein sulfhydryl (NPSH) present in most mammalian cells. BSO exposures used in these experiments were not cytotoxic with the one exception that 2.0 mM BSO/24 hr reduced cell viability to approx.50%. However, alterations in either the cell doubling time(s) or the cell age density distribution(s) were not observed with the BSO exposures used to determine its radiosensitizing effect. BSO significantly radiosensitized hypoxic, but not aerobic, CHO cells when the GSH and NPSH concentrations were reduced to <10 and 20% of control, respectively, and maximum radiosensitivity was even achieved with μM concentrations of BSO. Furthermore, BSO exposure also enhanced the radiosensitizing effect of various concentrations of misonidazole on hypoxic CHO cells

  15. Cell cycle effects for radiosensitivity after heavy ion exposure

    International Nuclear Information System (INIS)

    In order to study the relative contribution of the two major DNA double-strand break (DSB) repair pathways, non-homologous end-joining (NHEJ) and homologous recombinational repair (HRR), to the repair of DSBs and non-DSB clustered DNA damage induced by high linear energy transfer (LET) ionizing radiation through the cell cycle, we exposed wild type (WT), NHEJ-deficient, and HRR-deficient Chinese hamster ovary (CHO) cells synchronized by mitotic shake-off to accelerated heavy ions and X-rays. The cell cycle-dependent variation in survival observed in WT cells after X-irradiation was not observed after exposure to 500 MeV/amu iron ions. Non-homologous end joining (NHEJ) and homologous recombinational repair (HRR)-defective cells showed different patterns of cell cycle-dependent radiosensitivity after X-irradiation compared to WT cells, that were likewise significantly attenuated after iron ion exposures. Higher relative biological effectiveness for several other accelerated heavy ions (C, Ne, Si, Ar) of differing LETs was observed for cells exposed in S phase compared to cells exposed in G1. We also observed that HRR deficiency, unlike NHEJ deficiency, did not affect the progression of irradiated G2 cells into mitosis, thus contributing to increased cell killing observed in G2-phase HRR-deficient cells. The HRR-deficient cells showed significantly increased levels of chromatid-type aberrations that correlated with their cell cycle pattern of survival after both X- and iron ion irradiation. Our results suggest that high LET radiation produces not only complex DSBs but also complex non-DSB clustered lesions that specifically require the HRR-mediated repair of these lesions if encountered during DNA replication. (author)

  16. Metformin kills and radiosensitizes cancer cells and preferentially kills cancer stem cells

    OpenAIRE

    Chang W. Song; Hyemi Lee; Dings, Ruud P. M.; Brent Williams; John Powers; Troy Dos Santos; Bo-Hwa Choi; Heon Joo Park

    2012-01-01

    The anti-cancer effects of metformin, the most widely used drug for type 2 diabetes, alone or in combination with ionizing radiation were studied with MCF-7 human breast cancer cells and FSaII mouse fibrosarcoma cells. Clinically achievable concentrations of metformin caused significant clonogenic death in cancer cells. Importantly, metformin was preferentially cytotoxic to cancer stem cells relative to non-cancer stem cells. Metformin increased the radiosensitivity of cancer cells in vitro, ...

  17. Suppression of autophagy augments the radiosensitizing effects of STAT3 inhibition on human glioma cells

    International Nuclear Information System (INIS)

    Radiotherapy is an essential component of the standard therapy for newly diagnosed glioblastoma. To increase the radiosensitivity of glioma cells is a feasible solution to improve the therapeutic effects. It has been suggested that inhibition of signal transducer and activator of transcription 3 (STAT3) can radiosensitize glioma cells, probably via the activation of mitochondrial apoptotic pathway. In this study, human malignant glioma cells, U251 and A172, were treated with an STAT3 inhibitor, WP1066, or a short hairpin RNA plasmid targeting STAT3 to suppress the activation of STAT3 signaling. The radiosensitizing effects of STAT3 inhibition were confirmed in glioma cells. Intriguingly, combination of ionizing radiation exposure and STAT3 inhibition triggered a pronounced increase of autophagy flux. To explore the role of autophagy, glioma cells were treated with 3-methyladenine or siRNA for autophagy-related gene 5, and it was demonstrated that inhibition of autophagy further strengthened the radiosensitizing effects of STAT3 inhibition. Accordingly, more apoptotic cells were induced by the dual inhibition of autophagy and STAT3 signaling. In conclusion, our data revealed a protective role of autophagy in the radiosensitizing effects of STAT3 inhibition, and inhibition of both autophagy and STAT3 might be a potential therapeutic strategy to increase the radiosensitivity of glioma cells. - Highlights: • Inactivation of STAT3 signaling radiosensitizes malignant glioma cells. • STAT3 inhibition triggers a significant increase of autophagy flux induced by ionizing radiation in glioma cells. • Suppression of autophagy further strengthens the radiosensitizing effects of STAT3 inhibition in glioma cells. • Dual inhibition of autophagy and STAT3 induce massive apoptotic cells upon exposure to ionizing radiation

  18. Suppression of autophagy augments the radiosensitizing effects of STAT3 inhibition on human glioma cells

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Xiaopeng; Du, Jie; Hua, Song; Zhang, Haowen; Gu, Cheng; Wang, Jie; Yang, Lei; Huang, Jianfeng; Yu, Jiahua, E-mail: yujiahua@suda.edu.cn; Liu, Fenju, E-mail: fangsh@suda.edu.cn

    2015-01-15

    Radiotherapy is an essential component of the standard therapy for newly diagnosed glioblastoma. To increase the radiosensitivity of glioma cells is a feasible solution to improve the therapeutic effects. It has been suggested that inhibition of signal transducer and activator of transcription 3 (STAT3) can radiosensitize glioma cells, probably via the activation of mitochondrial apoptotic pathway. In this study, human malignant glioma cells, U251 and A172, were treated with an STAT3 inhibitor, WP1066, or a short hairpin RNA plasmid targeting STAT3 to suppress the activation of STAT3 signaling. The radiosensitizing effects of STAT3 inhibition were confirmed in glioma cells. Intriguingly, combination of ionizing radiation exposure and STAT3 inhibition triggered a pronounced increase of autophagy flux. To explore the role of autophagy, glioma cells were treated with 3-methyladenine or siRNA for autophagy-related gene 5, and it was demonstrated that inhibition of autophagy further strengthened the radiosensitizing effects of STAT3 inhibition. Accordingly, more apoptotic cells were induced by the dual inhibition of autophagy and STAT3 signaling. In conclusion, our data revealed a protective role of autophagy in the radiosensitizing effects of STAT3 inhibition, and inhibition of both autophagy and STAT3 might be a potential therapeutic strategy to increase the radiosensitivity of glioma cells. - Highlights: • Inactivation of STAT3 signaling radiosensitizes malignant glioma cells. • STAT3 inhibition triggers a significant increase of autophagy flux induced by ionizing radiation in glioma cells. • Suppression of autophagy further strengthens the radiosensitizing effects of STAT3 inhibition in glioma cells. • Dual inhibition of autophagy and STAT3 induce massive apoptotic cells upon exposure to ionizing radiation.

  19. Rejoining of prematurely condensed chromosomes in radiosensitive xrs-5 cells

    International Nuclear Information System (INIS)

    Xrs-5 cells, a radiosensitive, DNA double strand break repair deficient mutant of CHO cells have been studied with the premature chromosome condensation (PCC) technique. This mutant displayed a higher number of initial chromosome breaks with x-ray treatment as well as partial deficiency in the rejoining of interphase chromosome breaks with the standard PCC protocol. Moreover, hypertonic treatment during the incubation period which allowed for PCC did not change the yield of PCC breaks in x-irradiated xrs-5 cells. Notably the number of PCC breaks after treatment with hypertonic media is similar in CHO and xrs-5 cells. Recently, a gene product responsible for the xrs phenotype was identified as a Ku-like DNA end binding protein. The present paper summarizes completed information regarding the induction and repair of the α- and β-forms of PCC breaks in xrs-5 cells and demonstrates that this gene product predominantly affects the fast form (β-form) of interphase chromosome breaks

  20. Radiosensitivity evaluation of Human tumor cell lines by single cell gel electrophoresis

    International Nuclear Information System (INIS)

    Objective: To explore the feasibility of determining radiosensitivity of human tumor cell lines in vitro using single cell gel electrophoresis (SCGE). Methods: Three human tumor cell lines were selected in this study, HepG2, EC-9706 and MCF-7. The surviving fraction (SF) and DNA damage were detected by MTT assay, nested PCR technique and comet assay respectively. Results: MTT assay: The SF of HepG2 and EC-9706 after irradiated by 2, 4 and 8 Gy was lower significantly than that of MCF-7, which showed that the radiosensitivity of HepG2 and EC-9706 was higher than that of MCF-7. But there was no statistical difference of SF between HepG2 and EC-9706. SCGE: The difference of radiosensitivity among these three tumor cell lines was significant after 8 Gy γ-ray irradiation. Conclusion: The multi-utilization of many biological parameter is hopeful to evaluate the radiosensitivity of tumor cells more objectively and exactly. (authors)

  1. Dibutyryl cyclic AMP reduces the radiosensitivity of cultured endothelial cells

    International Nuclear Information System (INIS)

    The purpose of this study was to determine whether dibutyryl cyclic AMP modifies the radiosensitivity of confluent monolayers of bovine aortic endothelial cells (BAEC). Three indices of BAEC function were monitored from 4-24 hrs after exposure to 1-10 Gy of 60Co gamma rays: the release of 51Cr from prelabeled cells, and release of lactate dehydrogenase (LDH) and plasminogen activator (PLA) into the culture medium. There was a time- and radiation dose-dependent increase in 51Cr, LDH and PLA release from the BAEC, detectable within 12 hrs after 5 Gy or higher, and by 24 hrs after 1 Gy or higher. This increased release was accompanied by a radiation dose-dependent decrease in 51Cr and LDH, and an increase in PLA activity in the lysate of cells adherent to the monolayer at 24 hrs. The continuous presence of cAMP from 1 hr before to 24 hrs after irradiation reduced all of these radiation reactions, although mM concentrations of cAMP were required for significant sparing. The presence of cAMP from 1 hr before to 10 min after irradiation had no effect on BAEC sensitivity, whereas cAMP added 10 min after irradiation was fully as effective as continuously administered drug. Thus, cultured BAEC exhibit membrane dysfunction within 24 hrs after clinically relevant radiation doses, and this dysfunction is ameliorated by cAMP present after irradiation

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

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

    2013-05-01

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

  5. Thermal enhancement of radiosensitivity in normal and ataxia telangiectasia human cells

    International Nuclear Information System (INIS)

    Normal human and ataxia telangiectasia (AT) fibroblasts were tested for enhancement of radiosensitivity by hyperthermia. In normal fibroblasts, thermal enhancement of radiosensitivity occurred at 42.00 and 45.00C and was greatest for simultaneous treatments of heat and radiation. This thermal enhancement decreased, as an incubation time at 37.00C was introduced either between heat and X-ray, or X-ray and heat, treatments. AT cells were more radiosensitive (D0=0.67 Gy) than normal cells (D0=1.4 Gy). Heating at 42.00 or 45.00C resulted in enhanced radiosensitivity, which was equal for heating before, during or after irradiation. These data show that normal human fibroblasts can recover from heat and radiation treatments, while AT fibroblasts lack this ability

  6. Apoptosis and radiosensitization of Hodgkin cells by proteasome inhibition

    International Nuclear Information System (INIS)

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

  7. Hormonal and cellular factors affecting immature sertoli cells radiosensitivity in rat fetus

    International Nuclear Information System (INIS)

    Immature Sertoli cells population was studied after irradiation either in hypophysectomised (decapited) or in germ cell free foetus (busulfan treated embryo). Decapitation did not modify the 10 % reduction of immature Sertoli cells after 1.5 Gy irradiation. But, without germ cells, immature Sertoli cells were more radiosensitive

  8. Comparative proteomic study of nasopharyngeal carcinoma cell lines with different radiosensitivity

    International Nuclear Information System (INIS)

    Objective: To investigate the proteins which were associated with radiosensitivity of nasopharyngeal carcinoma (NPC) cells and could be used to predict the radiosensitivity. Methods: A radioresistant subclone cell line CNE-2 (R743) derived from NPC cell line CNE-2 was established. Radiosensitivity and cell cycle characteristics of CNE-2 and CNE-2 (R743) were examined and compared by clonogenic survival assay and flow cytometry. The total proteins from the two cell lines were extracted and separated by two-dimensional gel electrophoresis, and the images were analyzed by Image Master 7.0 analysis software. Differentially expressed proteins in the two cell lines were identified through MALDI-TOF/TOF peptide mass fingerprint and searched in the protein sequence database. The protein expressions were confirmed by RT-PCR and Western blot. Results: Totally seven differentially expressed proteins were identified, six of which were upregulated and one downregulated in the radioresistant CNE-2 (R743), compared with those of CNE-2. Three out of the seven, Annexin A2, Tropomyosin 4 and GRP78 were upregulated in the CNE-2 (R743), which were confirmed by Western blot and RT-PCR (t=24.22, 24.20, 29.19, P<0.05). Conclusions: Differentially expressed proteins might be involved in different radiosensitivities of nasopharyngeal carcinoma cell lines, among which Annexin A2, Tropomyosin 4 and GRP78 could be the candidate biomarkers for predicting radiosensitivity of nasopharyngeal carcinoma cells. (authors)

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

    Directory of Open Access Journals (Sweden)

    Zhao Lei

    2012-12-01

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

  10. Trypsin-induced changes in cell shape and chromatin structure result in radiosensitization of monolayer Chinese hamster V79 cells

    International Nuclear Information System (INIS)

    Trypsin is the enzyme commonly used to prepare single cell suspensions from monolayer and spheroid cultures, both to determine survival and to assay DNA damage. Trypsin induces rounding, dissociation and radiosensitization of anchorage-dependent cells. Radiosensitivity and chromatin structure were compared between trypsin-treated (0.05%) round V79 cells from monolayers and spheroids vs. untreated spread monolayer cells in situ. The fluorescent halo technique was used to measure the changes in DNA supercoiling in nucleoids isolated from control and irradiated round and spread cells. Maximal halo diameters, the amount of initial and residual radiation-induced SNA damage and the radiosensitivity were higher in round cells than in spread monolayer V79 cells. The effects on cellular radiosensitivity and maximal halo diameter of other agents which also round and dissociate cells, e.g. 0.25% trypsin, pronase E and a non-enzymatic cell-dissociation solution, were similar to those of 0.05% trypsin. In LY-S cells, which are anchorage-independent, DNA loop size, the initial amount of DNA damage and radiosensitivity were not affected by trypsin. We suggest that the higher radiosensitivity of anchorage-dependent cells under immediate trypsinization and plating conditions, compared to cells with postirradiation in situ repair incubation, is due to correlated changes in cell shape and chromatin structure. (author)

  11. Differential radiosensitivity in cultured B-16 melanoma cells following interrupted melanogenesis induced by glucosamine

    Energy Technology Data Exchange (ETDEWEB)

    Mileo, A.M.; Mattei, E.; Fanuele, M.; Delpino, A.; Ferrini, U. (Regina Elena Cancer Institute, Rome (Italy))

    1989-05-01

    The relationship between cell pigmentation and radiosensitivity was investigated in a cell model in which melanogenesis was suppressed by a glycosylation inhibitor. It was found that X-irradiation of melanotic B-16 melanoma cells and their amelanotic counterparts, obtained by glucosamine treatment, showed an inverse correlation between radiosensitivity and melanin contents. Since melanogenesis interruption by glucosamine does not affect the DNA repair capacity of nonpigmented cells, it is likely that intracellular melanins play a role in the relative resistance of pigmented cells to X-irradiation.

  12. Differential radiosensitivity in cultured B-16 melanoma cells following interrupted melanogenesis induced by glucosamine

    International Nuclear Information System (INIS)

    The relationship between cell pigmentation and radiosensitivity was investigated in a cell model in which melanogenesis was suppressed by a glycosylation inhibitor. It was found that X-irradiation of melanotic B-16 melanoma cells and their amelanotic counterparts, obtained by glucosamine treatment, showed an inverse correlation between radiosensitivity and melanin contents. Since melanogenesis interruption by glucosamine does not affect the DNA repair capacity of nonpigmented cells, it is likely that intracellular melanins play a role in the relative resistance of pigmented cells to X-irradiation

  13. Pronounced radiosensitization of cultured human cancer cells by COX inhibitor under acidic microenvironment

    International Nuclear Information System (INIS)

    Purpose: To demonstrate the influence of pH on the cytotoxicity and radiosensitization by COX (cyclooxygenase) -1 and -2 inhibitors using established human cancer cells in culture. Methods and Materials: Nonselective COX inhibitor, ibuprofen (IB), and selective COX-2 inhibitor, SC-236, were used to determine the cytotoxicity and radiosensitization at varying pH of culture media. Human colon carcinoma cell line (HT-29) was exposed to the drug alone and in combination with radiation at different pH of the cell culture media. The end point was clonogenic ability of the single-plated cells after the treatment. Results: Cytotoxicity and radiosensitization of IB increased with higher drug concentration and longer exposure time. The most significant radiosensitization was seen with IB (1.5 mM) for 2-h treatment at pH 6.7 before irradiation. The dose-modifying factor as defined by the ratio of radiation doses required to achieve the same effect on cell survival was 1.8 at 10% survival level. In contrast, SC-236 (50 μM for 2-8 h) showed no pH-dependent cytotoxicity. There was modest increase in the cell killing at lower doses of radiation. Conclusion: An acidic pH was an important factor affecting the increased cytotoxicity and radiosensitization by ibuprofen. Radiation response was enhanced at shoulder portion of the cell survival curve by selective COX-2 inhibitor

  14. Effect of hydrocortisone on radiosensitivity of hemopoietic stem cells

    International Nuclear Information System (INIS)

    Differentiation and radiosensitivity of colony-forming units (CFU) of the bone marrow and spleen were studied in the course of one month after a single injection of hydrocortisone to mice (5 mg/mouse). The direction of differentiation of CFU from different organs was found to change drastically. CFU of the bone marrow stimulated erythropoiesis and of spleen, myelopoiesis which is different from what we have in normal mice. Study of the radiosensitivity of CFU from various organs by the ''splenic colony'' test did not show any variations in the values of D0 and the extrapolation number, whereas the ''bone marrow colony'' test exhibited considerable atleration of the CFU radiosensitivity. Radioresistance of CFU from bone marrow decreased while that of splenic CFU increased compared with controls. The phenomena described are probably due to redistribution of T-lymphocytes in response to the hydrocortisone administration

  15. Evaluation of Radiosensitivity of HeLa Cells Infected with Polio Virus Irradiated by Co 60

    Directory of Open Access Journals (Sweden)

    F Seif

    2008-04-01

    Full Text Available ABSTRACT: Introduction & Objective: The main purpose of radiotherapy is exposing enough doses of radiation to tumor tissue and protecting the normal tissues around it. Tumor dose for each session in radiotherapy will be considered based on radiosensitivity of the tissues. The presence of viral diseases in tumoral area can affect the radiosensitivity of cells. This study aimed to evaluate the radiosensitivity of Hela cells infected with poliomyelitis virus irradiated by Co 60. Materials & Methods: In this study, the radiosensitivity of HeLa cells, with or without the viral infection, after gamma radiation of cobalt 60, was assessed. Results: Results of comparison of the radisensitivity of infected and uninfected cells indicates that after 2 Gy irradiation by Co 60, polio infection in low, moderate and high virus load, increases the cell death by 20-30%, 30-40% and 70-90% respectively. Conclusion : Radiosensitivity of tumoral cells increase when they are infected with viral agents. Results of this study showed that non cancer diseases should be considered when prescribing dose fraction in radiotherapy of cancers.

  16. Radiosensitization Effect of STI-571 on Pancreatic Cancer Cells In Vitro

    International Nuclear Information System (INIS)

    Purpose: To examine STI-571-induced radiosensitivity in human pancreatic cancer cells in vitro. Methods and Materials: Three human pancreatic cancer cell lines (Bxpc-3, Capan-1, and MiaPaCa-2) exhibiting different expression levels of c-Kit and platelet-derived growth factor receptor β (PDGFRβ) and showing different K-ras mutation types were used. For evaluation of the antitumor activity of STI-571 in combination with radiation, clonogenic survival assays, Western blot analysis, and the annexin V/propidium iodide assay with microscopic evaluation by 4',6-diamidino-2-phenylindole were conducted. Results: Dramatic phosphorylated (p)-c-Kit and p-PDGFRβ attenuation, a modest dose- and time-dependent growth inhibition, and significant radiosensitization were observed after STI-571 treatment in view of apoptosis, although the levels of growth inhibition and increased radiosensitization were different according to cell lines. The grades of radiosensitivity corresponded to the attenuation levels of p-c-Kit and p-PDGFRβ by STI-571, particularly to those of p-c-Kit, and the radiosensitivity was partially affected by K-ras mutation in pancreatic cancer cells. Among downstream pathways associated with c-Kit or PDGFRβ, p-PLCγ was more closely related to radiosensitivity compared with p-Akt1 or p-extracellular signal-regulated kinase 1. Conclusion: STI-571 enhances radiation response in pancreatic cancer cells. This effect is affected by the attenuation levels of p-c-Kit or p-PDGFRβ, and K-ras mutation status. Among them, p-c-Kit plays more important roles in the radiosensitivity in pancreatic cancer compared with p-PDGFRβ or K-ras mutation status.

  17. Effect of antisence VEGF on the radiosensitivity of esophageal cancer cells in vitro

    International Nuclear Information System (INIS)

    Objective: To investigate the effect of' antisense VEGF on the cell proliferation, VEGF protein expression and radiosensitivity of esophageal cancer cells in vitro. Methods: Fragments of antisense cDNA, empty vector plasmid DNA and antisense oligodeoxynucleotide of VEGF were transfected into esophageal cancer (TE-1) cells mediated with lipofectamine, respectively. Cell proliferating rate and apoptotic rate of these groups were edetected by MIT and FCM methods, respectively. After irradiation, the expression of VEGF in transfected cells were detected by using RT-PCR and Western blotting. The radiosensitivity of transfected cells were analyzed with colony forming assay. Results: After antisense cDNA plasmid and antisense oligodeoxynucleotide of VEGF were transfected successfully into TE-1 cells, expressions of VEGF protein decreased, however, the changes in cell growth rate and distribution of cell cycle, and the apoptotic rate were not observed in these transfected cells. After irradiation, the radiosensitivity of transfected TE-1 cells were increased, but there was no significant difference in cell growth rate among groups. The apoptotic rates in antisense groups increased slightly compared to TE-1 and TE-1-E groups. Conclusions: Expression of VEGF mRNA and VEGF protein were significantly suppressed in TE-1 cells transfected by antisense cDNA and antisense oligodeoxynucleotide of VEGF. After irradiation, the radiosensitivity of the transfected TE-1 cells was increased. (authors)

  18. Comet assay as a predictive assay for radiosensitivity of two human brain tumor cell lines

    International Nuclear Information System (INIS)

    Micronucleus assay and comet assay were compared as a predictive assay for radiosensitivity of tumors. Two human brain tumor cell lines, Becker (derived from astrocytoma) and ONS76 (derived from medulloblastoma) were used. Colony methods as the gold standard showed ONS76 as radiosensitive and Becker as radioresistant cell lines. Micronucleus assay revealed no different radiosensitivity between them. With comet assay, Becker cells received irradiation showed less damage to the DNA and faster repair of the damage than ONS76 cells did. The results correlate with those from colony methods. Comet assay is simple and rapid method for clinical use and it has an advantage not to establish the primary culture. Moreover, the results of comet assay showed not only DNA damage but also repair from the damage. It is concluded that comet assay is a superior method than micronucleus assay and has a potent candidate for clinical predictive assay. (author)

  19. Evaluation of radiosensitivity of nasopharyngeal cancer cells by in situ nick translation

    International Nuclear Information System (INIS)

    The radiosensitivity of two nasopharyngeal cell lines was evaluated, which had been treated with γ-rays by in situ nick translation (ISNT). The results indicated that the incorporation rate of dNTP of the two cell lines increased with the radiation dose. Good correlations were found between the radiosensitivity determined by the in situ nick translation assay and confirmed by the colony-forming assay in CNE and CNE-2Z cell lines. Although this report deals with cultured cells, the described technique of detecting DNA nick in situ without destruction of morphology seems to be applicable to tissue section. It may be possible to use it as a tool for predicting radiosensitivity of cancerous tissues treated with γ-rays

  20. Effect of microenviroment hypoxia on glioma cells radiosensitivity through cancer stem cell pathway

    International Nuclear Information System (INIS)

    Objective: To investigate the effect of microenviroment hypoxia on glioma cells radiosensitivity through cancer stem pathway, and to explore the related mechanism. Methods: Glioma cell lines SHG44 and U251 were cultured in normoxia (20% O2) or continuous hypoxia (1% O2) for 12 and 24 h. The fraction of glioma cells with positive expression of CD133 was assayed by flow cytometry. The radiosensitivity of glioma cells was determined by clonogenic cell assay. Western blotting was used to investigate the expressions of HIF-1 α and its downstream gene Notch 1. Results: The fraction of glioma cells with positive expression of CD133 was higher after hypoxic culture for 12 and 24 h than that of the corresponding cells cultured in normoxia. Compared to the cells cultured in normoxia, SF2 (survival fraction at 2 Gy) were enhanced significantly in SHG44 and U251 cells cultured in hypoxia for 12 and 24 h. The OER (oxygen-enhancement ratio) of SHG44 cells in hypoxia for 12 and 24 h was 1.54 and 1.38, respectively. The OER of U251 cells was 1.44 and 1.23, respectively. The radiosensitivity of these two cell line was decreased in hypoxia. The protein expressions of HIF-1 α and Notch 1 genes were elevated more significantly for cells cultured in hypoxia for 12 and 24 h than for those in normoxia. Conclusions: Microenviroment hypoxia could increase the radioresistance of glioma cells through enrichment of cancer stem cells, and HIF-1 α-Notch 1 signal pathway may play an important role in this process. (authors)

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

    Science.gov (United States)

    Hirai, Takahisa; Saito, Soichiro; Fujimori, Hiroaki; Matsushita, Keiichiro; Nishio, Teiji; Okayasu, Ryuichi; Masutani, Mitsuko

    2016-09-01

    The poly(ADP-ribose) polymerase (PARP)-1 regulates DNA damage responses and promotes base excision repair. PARP inhibitors have been shown to enhance the cytotoxicity of ionizing radiation in various cancer cells and animal models. We have demonstrated that the PARP inhibitor (PARPi) AZD2281 is also an effective radiosensitizer for carbon-ion radiation; thus, we speculated that the PARPi could be applied to a wide therapeutic range of linear energy transfer (LET) radiation as a radiosensitizer. Institutes for biological experiments using proton beam are limited worldwide. This study was performed as a cooperative research at heavy ion medical accelerator in Chiba (HIMAC) in National Institute of Radiological Sciences. HIMAC can generate various ion beams; this enabled us to compare the radiosensitization effect of the PARPi on cells subjected to proton and carbon-ion beams from the same beam line. After physical optimization of proton beam irradiation, the radiosensitization effect of the PARPi was assessed in the human lung cancer cell line, A549, and the pancreatic cancer cell line, MIA PaCa-2. The effect of the PARPi, AZD2281, on radiosensitization to Bragg peak was more significant than that to entrance region. The PARPi increased the number of phosphorylated H2AX (γ-H2AX) foci and enhanced G2/M arrest after proton beam irradiation. This result supports our hypothesis that a PARPi could be applied to a wide therapeutic range of LET radiation by blocking the DNA repair response. PMID:27425251

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

    Czech Academy of Sciences Publication Activity Database

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

    2010-01-01

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

  3. Macrophages enhance the radiosensitizing activity of lipid A: A novel role for immune cells in tumor cell radioresponse

    International Nuclear Information System (INIS)

    Purpose: This study examines whether activated macrophages may radiosensitize tumor cells through the release of proinflammatory mediators. Methods and materials: RAW 264.7 macrophages were activated by lipid A, and the conditioned medium (CM) was analyzed for the secretion of cytokines and the production of nitric oxide (NO) through inducible nitric oxide synthase (iNOS). EMT-6 tumor cells were exposed to CM and analyzed for hypoxic cell radiosensitivity. The role of nuclear factor (NF)-κB in the transcriptional activation of iNOS was examined by luciferase reporter gene assay. Results: Clinical immunomodulator lipid A, at a plasma-relevant concentration of 3 μg/mL, stimulated RAW 264.7 macrophages to release NO, tumor necrosis factor (TNF)-α, and other cytokines. This in turn activated iNOS-mediated NO production in EMT-6 tumor cells and drastically enhanced their radiosensitivity. Radiosensitization was abrogated by the iNOS inhibitor aminoguanidine but not by a neutralizing anti-TNF-α antibody. The mechanism of iNOS induction was linked to NF-κB but not to JAK/STAT signaling. Interferon-γ further increased the NO production by macrophages to a level that caused radiosensitization of EMT-6 cells through the bystanding effect of diffused NO. Conclusions: We demonstrate for the first time that activated macrophages may radiosensitize tumor cells through the induction of NO synthesis, which occurs in both tumor and immune cells

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

    International Nuclear Information System (INIS)

    Objective: To provide more convincing evidences and experimental data for exploring vanillin derivative BVAN08, 6-bromine-5-hydroxy-4-methoxy-benzaldehyde, as a new anticancer drug, and to investigate the effect on the growth, radiosensitization of human glioma cell line U-251 and the relative mechanism. Methods: The effect of BVAN08 on cell proliferation of U-251 and radiosensitivity to 60Co γ-rays (irradiation dose rate 2.3 Gy/min) were analyzed with MTT and colony-forming ability assay. Change in cellular morphology was observed by using light microscope. Change in cell cycle and apoptosis was detected with flow cytometry. The autophagy was observed by using TEM (irradiation dose rate is transmission electron microscope). DNA-PKcs protein level was detected through Western blot analysis. Results: BVAN08 exhibited a dose- and time-dependent inhibition on the proliferation of U-251 cells during the concentration range of 10-100 mol/L (t=1.83-3.07, P50 at 48 h and 72 h after administration with BVAN08 were 55.3 and 52.7 mol/L, respectively. Obvious G2/M arrest was induced in U-251 cells after 4 h administration with BVAN08, and reached peck at 12 h. The G2/M population reached 63.3% in U-251 cells after 12 h administration of 60 μmol/L BVAN08 and kept increasing with the time, while both apoptosis and autophagic cell death were induced. The most effective radiosensitization time for BVAN08 treatment was 12 h before irradiation. The enhancement ratio of radiosensitivity was 3.14 for 20 μmol/L of BVAN08 12 h before 2 Gy irradiation. Conclusions: BVAN08 can induce apoptosis as radiosensitizing effect might be associated with the induction of G2/M arrest and inhibition of DNA-PKcs expression. BVAN08 seemed to be a promising radiosensitizing anticancer drug. (authors)

  5. Radiosensitizing efficiency of sodium glycididazole on V79 cells in vitro

    International Nuclear Information System (INIS)

    Radiosensitizing effect of sodium glycididazole (SGDD) on the hypoxic V79 cells by standard in vitro colon formation method has been further studied. The results showed its toxicity was low. Its ID50 in cells under hypoxic and aerobic condition were 23.5 and 35.7 mmol/L respectively. These indicated that SGDD showed more toxicity under hypoxic than under aerobic condition (p1.6 was 0.48 mmol/L. Its maximum SER was 2.3 at 1.38 mmol/L. Comparisons of radiosensitizing effect of SGDD versus MISO and its mother compound (metronidazole) under the same experimental condition, SER for SGDD, MISO and metronidazole were 1.75, 1.53 and 1.07 at 0.3 mmol/L respectively. SGDD showed more radiosensitizing efficiency than MISO and much greater than metronidazole. This study further confirms our previous results i.e. SGDD is a hypoxic radiosensitizer with low toxic, high efficiency and selectively enhances the radiosensitivity of hypoxic cells for tumor radiotherapy

  6. Reaction between nitracrine and glutathione: implications for hypoxic cell radiosensitization and cytotoxicity

    International Nuclear Information System (INIS)

    Nitracrine (NC) is an electron affinic DNA intercalating agent and a potent hypoxia-selective cytotoxin and radiosensitizer in cell culture. Although NC is too cytotoxic and too rapidly metabolized to provide hypoxic cell radiosensitization in tumors, it is of mechanistic interest as an example of a DNA affinic radiosensitizer. We have observed a rapid chemical reaction between NC and reduced glutathione (GSH), which suggests that the observed potent in vitro cytotoxicity and radiosensitization might be dependent on thiol depletion by the large extracellular reservoir of drug. However, no GSH depletion was observed under conditions providing radiosensitization or rapid cell killing, and prior depletion of GSH by buthionine sulphoximine had no effect on cytotoxicity or formation of macromolecular adducts. Further, the intracellular reaction of NC with GSH is slower than predicted on the basis of the measured second order rate constant and the total intracellular concentrations of both species. The results are consistent with a role for DNA binding in protecting NC from reaction with GSH, and in improving the efficiency with which reduced electrophilic metabolites react with DNA in preference to GSH

  7. Effect of STAT1 on radiosensitivity of renal clear cell carcinoma

    International Nuclear Information System (INIS)

    Objective: To study the expression of signal transducer and activator of transcription 1 (STAT1) in human renal clear cell carcinoma (RCC) and the effect of STAT1 inhibition on the radiosensitivity of RCC. Methods: The expression of STAT1 in 34 human RCC samples compared with 12 normal kidney tissues was examined by immunohistochemistry method. For in vitro experiments, a human RCC cell line, CRL-1932, was used. Western blotting was performed to evaluate the expression of total and phosporylated STAT1. Fludarabine and siRNA were respectively used to inhibit the expression of STAT1 in CRL-1932 cells. Clonogenic assay and trypan blue staining assay were used to evaluate the radiosensitivity of CRL-1932 cells. Results: The expression of both total and phosphorylated STAT1 in human RCC samples was significantly higher when compared to normal kidney tissues. Similarly, the expression of STAT1 was higher in CRL-1932 cells when compared to fibroblast and Wilm's tumor cell lines. STAT1 expression was inhibited by both fludarabine and siRNA. Radiosensitivity of CRL-1932 cells was enhanced by both fludarabine and siRNA induced STAT1 inhibition. Conclusions: STAT1 is over-expressed in both human RCC tissue and cell line. Inhibition of STAT1 can enhance the radiosensitivity of RCC cells. (authors)

  8. Usefulness of DNA repair genes in prediction and potentiation of radiosensitivity in tumor cells

    International Nuclear Information System (INIS)

    Radiotherapy is one of the common treatment modalities for cancer. However, owing to the differences in intrinsic radiosensitivity of the different tumor types, a significant variation in therapeutic response is observed during radiotherapy leading to ineffective killing of tumor cells or occasional adverse effects in normal tissues. Hence, an optimization of radiation dose in clinical practice based on the radiosensitivity of individual patients and tumor types is of paramount importance. From this perspective, prediction of radiosensitivity of tumor tissues and understanding about molecular determinants of radiosensitivity can help in improving the efficacy of radiation therapy. Therefore, in the present study, expression of genes which are involved in DNA damage response and cytoprotective pathways were studied to evaluate their use in predicting the radiosensitivity of tumor cells using six different tumor cells (HT1080, DU145, MCF7, A549, PC3 and HT29). Initially the radiosensitivity profile of these tumor cells has been studied using clonogenic survival assay. Then the expression profile of genes, which are involved in crucial radiation response pathways like, DNA damage, repair, apoptosis and redox regulation were analyzed by real time q-PCR (either 2 Gy or 6 Gy). The fold change in expression was calculated for different genes and was correlated with clonogenic survival. Out of 15 genes analyzed, three genes (HSP70, KU80 and RAD51) showed change in gene expression in accordance with their radiosensitivity. The expression of these three genes also showed a significant positive correlation with survival fraction. The 'r' values observed were 0.97, 0.99, and 0.97 for HSP70, KU80 and RAD51, respectively. Since these genes are involved in DNA repair pathways, we have investigated the effect of inhibition of DNA-PK (a protein involved in the non-homologous end joining and consists of Ku70/KU80 complex and DNA-PKcs), in potentiating the radiation induced damage in

  9. Predictive radiosensitivity of differentiated thyroid tumors: comparative study by the fish and the cell clonogenicity

    International Nuclear Information System (INIS)

    To establish a quick and reliable test of the radiosensitivity of thyroid differentiated tumor cells, the technique of hybridization in situ in fluorescence or F.I.S.H. has been used. It consists in, after painting a given chromosome, to evaluate the radioinduced translocations in chromosomes. In order to validate this method as predictive test, we have compared the results got with it to these ones given by the reference technique called survival curves. The F.I.S.H. technique proves to be quick, reliable of the radiosensitivity of thyroid differentiated tumor cells and so can be used in place of the heavy technique of survival curves. (N.C.)

  10. Cellular radiosensitivity of primary and metastatic human uveal melanoma cell lines

    NARCIS (Netherlands)

    G.J.M.J. van den Aardweg (Gerard J. M.); N.C. Naus (Nicole); A.C. Verhoeven; J.E.M.M. de Klein (Annelies); G.P.M. Luyten (Gré)

    2002-01-01

    textabstractPURPOSE: To investigate the radiosensitivity of uveal melanoma cell lines by a clonogenic survival assay, to improve the efficiency of the radiation regimen. METHODS: Four primary and four metastatic human uveal melanoma cell lines were cultured in the presence of condi

  11. Correlation between residual level of DNA double-strand breaks and the radiosensitivity of cancer cells

    International Nuclear Information System (INIS)

    Objective: To understand the variation of the DNA double-strand break rejoining capacity among different cultured cancer cell lines and the primary cancer cells from brain cancer patients, and to explore the predictor of radiotherapy responses of cancers. Methods: DNA double-strand breaks (DSBs) were induced by 60Co γ-irradiation. Pulsed-field gel electrophoresis was used to analyze the initial production and rejoining of DNA DSBs. Radiosensitivity was determined by in vitro assay of clonogenic-forming capacity. Results: A wide variation of radiosensitivity, e.g. the survival parameter of Do varied from 0.65 to 2.15 Gy, was displayed among the eight cell lines derived from different type of cancers. Although differential level of initial DNA DSBs induced by 20 Gy γ-rays was observed among various cell lines, it was not correlated with the radiosensitivity. The deficiency of DNA DSB rejoining in radiosensitive cell lines was shown either in the early rapid-rejoining phase (SX-10 cells) or in the late slow-rejoining phase (A2780 cells). A significant relationship was observed between the residual level of DNA DSBs measured at 2 h post-20 Gy irradiation and the cellular radiosensitivity (D0 or SF2). The kinetic curves of rejoining DNA DSBs in the primary human brain tumor cells indicated a variation on DSB rejoining capacity among different individual tumor. The residual level of DNA DSBs after 2 h of rejoining post 20 Gy irradiation in primary human brain tumor cells is compatible to the results obtained in vitro culture cancer cell lines. Conclusions: The residual level of DNA DSBs is correlated with radioresistance of cancer cells, and the residual DNA damage is a useful parameter in predicting the response of tumor tissue to radiotherapy. (authors)

  12. Cellular radiosensitivity of small-cell lung cancer cell lines

    DEFF Research Database (Denmark)

    Krarup, M; Poulsen, H S; Spang-Thomsen, M

    1997-01-01

    PURPOSE: The objective of this study was to determine the radiobiological characteristics of a panel of small-cell lung cancer (SCLC) cell lines by use of a clonogenic assay. In addition, we tested whether comparable results could be obtained by employing a growth extrapolation method based on the...

  13. The chemopreventive flavonoid apigenin confers radiosensitizing effect in human tumor cells grown as monolayers and spheroids

    International Nuclear Information System (INIS)

    Apigenin, a common dietary flavonoid present in many fruits and vegetables, is a nonmutagenic chemopreventive agent. In the present study, we investigated the effect of apigenin on the radiosensitivity of SQ-5 cells, which are derived from a human lung carcinoma. Actively growing cells were incubated for 16 h at 37 deg C in medium containing 40 μM apigenin. The cells were then irradiated with X-rays and incubated with apigenin for a further 8 h. Radiosensitivity was assessed using a clonogenic assay. Apoptosis and necrosis were assessed using acridine orange/ethidium bromide double staining. Cells incubated with apigenin exhibited significantly greater radiosensitivity and apoptosis levels than cells not incubated with apigenin. Protein levels were measured by Western blotting. Incubation with apigenin increased protein expression of WAF1/p21 and decreased protein expression of Bcl-2. Furthermore, apigenin sensitized SQ-5 spheroids (cell aggregates growing in a three-dimensional structure that simulate the growth and microenvironmental conditions of in vivo tumors) to radiation. Thus, apigenin appears to be a promising radiosensitizing agent for use against human carcinomas. (author)

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

    Science.gov (United States)

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

    2016-01-01

    To explore the radiosensitivity of andrographolide on esophageal cancer cell line ECA109. The inhibition effects of andrographolide were measured using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium (MTT) assay. Clonogenic survival assay was used to evaluate the effects of andrographolide on the radiosensitivity of esophageal cancer cells. Immunofluorescence was employed to examine Bax expression. The changes in cell cycle distribution and apoptosis were assayed using flow cytometry. The expression of NF-κb/Cleaved-Caspase3/Bax/Bcl-2 was measured using Western blot analysis. DNA damage was detected via γ-H2AX foci counting. With a clear dose and time effects, andrographolide was found to inhibit the proliferation of esophageal cell line ECA109. The results of the clonogenic survival assay show that andrographolide could markedly enhance radiosensitivity (P Andrographolide caused a dose-dependent increase in Cleaved-Caspase3/Bax protein expression and a decrease in Bcl-2/NF-κb expression. Apoptosis in andrographolide-treated ECA-109 increased significantly compared with the apoptosis in the simple drug and radiation combined with drug groups (P andrographolide combined with radiation group increased the number of DNA double chain breaks. Andrographolide can increase the radiosensitivity of esophageal cell line ECA109. This result may be associated with the decrease in the NF-κb level and the induced apoptosis of esophageal cancer cells. PMID:25059546

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  17. Radiosensitivity in vitro of clonogenic and non-clonogenic glioblastoma cells obtained from a human brain tumour

    Energy Technology Data Exchange (ETDEWEB)

    Buronfosse, A.; Thomas, C.P.; Ginestet, C.; Dore, J.F. [Centre de Lutte Contre le Cancer Leon-Berard, 69 - Lyon (France)

    1994-11-01

    Cells obtained from a human glioblastoma (G5) were characterized and used to develop an assay measuring their radiosensitivity in vitro. Surviving fractions were estimated 12 days after irradiation by image analysis of the total surface occupied by the cells. This report evaluates 4 experimental factors which may influence the radiosensitivity in vitro of G5 cells: passage number, delay between plating and irradiation, cell density and clonal heterogeneity. The radiosensitivity of the G5 cell line was found to be passage-independent at least between passages 12 and 75. Experimental conditions influence the radiosensitivity as surviving fraction at 2 Gy (SF2) range from 90% (5 000 cells/well, irradiation 72 h after seeding) to 49% (2 500 cells per well, irradiation 24 h after seeding). The heterogeneity of the radiosensitivity is large at the clonal level as SF2 of six clones isolated from the G5 line were 45%, 50%, 72%, 74%, 79% and 84%. Finally, when G5 cells were irradiated at low cell density and at the beginning of the growth phase, the radiosensitivity measured with this assay is comparable to that obtained with a standard colony assay. We propose that this assay may be useful to determine the intrinsic radiosensitivity of cells obtained from human tumours. (authors). 24 refs., 8 figs., 2 tabs.

  18. Prediction of radiosensitivity in tumour cells: use of the alkaline comet assay to assess radiosensitivity in bladder and colorectal tumour cell lines

    International Nuclear Information System (INIS)

    Radiotherapy is the treatment of choice for a wide range of solid tumours yet it is impossible to predict which tumours will show a good response. We have investigated the radiosensitivity of a number of tumour cell lines (5 bladder and 4 colorectal) to verify whether the alkaline comet assay (ACA) can be used to predict tumour radiosensitivity. Preliminary studies showed that it is essential to carry out irradiations on cells pre-embedded in agarose to ensure that repair, prior to lysis, is kept to a minimum. Cells were embedded prior to irradiation, lysed and the comet tail moment analysed; this was compared to cell survival measured using a clonogenic assay. For all doses (0 - 6Gy) there was a good correlation between the two measures: r2 0.897 for bladder tumour cells and r2 = 0.929 for colorectal tumour cells. We also irradiated cells with 4Gy X-rays and measured initial damage, repair rate and residual damage. In both groups initial DNA damage and residual damage correlated with clonogenic survival; repair rate was very similar for the cell lines and was not predictive. One cell line (T24) had a pronounced shoulder on the radiation dose response curve such that there was a radioresistant response at 2 Gy and a radiosensitive response at 4 Gy. This change in response within the clinically relevant range emphasises that for a predictive test to have validity in the clinic it must be carried out in the clinically relevant range. The finding that initial damage varies between individual cell lines is consistent with some, but not all reports in the literature. We have also carried out nuclear texture analysis to measure phenotypic changes in DNA distribution and chromatin organisation. The results support the contention that organisation of nuclear chromatin is inherently different in different cell lines and may be significant in determining their response to radiation damage

  19. Slug inhibition increases radiosensitivity of oral squamous cell carcinoma cells by upregulating PUMA.

    Science.gov (United States)

    Jiang, Fangfang; Zhou, Lijie; Wei, Changbo; Zhao, Wei; Yu, Dongsheng

    2016-08-01

    As a new strategy, radio-gene therapy was widely used for the treatment of cancer patients in recent few years. Slug was involved in the radioresistance of various cancers and has been found to have an anti-apoptotic effect. This study aims to investigate whether the modulation of Slug expression by siRNA affects oral squamous cell carcinoma sensitivity to X-ray irradiation through upregulating PUMA. Two oral squamous cell carcinoma cell lines (HSC3 and HSC6) were transfected with small interfering RNA (siRNA) targeting Slug and subjected to radiotherapy in vitro. After transfection with Slug siRNA, both HSC3 and HSC6 cells showed relatively lower expression of Slug and higher expression of PUMA. The Slug siRNA transfected cells showed decreased survival and proliferation rates, an increased apoptosis rate and enhanced radiosensitivity to X-ray irradiation. Our results revealed that Slug siRNA transfection in combination with radiation increased the expression of PUMA, which contributed to radiosensitivity of oral squamous cell carcinoma cells. Thus, controlling the expression of Slug might contribute to enhance sensitivity of HSC3 and HSC6 cells toward X-ray irradiation in vitro by upregulating PUMA. PMID:27277529

  20. Thermo-radiosensitivity of the granulocyte and macrophage precursor cells of mice. II. - X irradiation effects and influence of hyperthermia on the radiosensitivity

    International Nuclear Information System (INIS)

    The effects of the X-irradiation on the viability of the granulocyte-macrophage precursors, has been determined by means of the agar diffusion chamber culture technique. The results show the high radiosensitivity of these cells, with survival parameter similar to those previously reported in the literature about different granulocyte-macrophage precursors. When a hyperthermic treatment is performed prior to the X-irradiation, a radiosensitization phenomenon is observed due to the synergism existent between hyperthermia and X rays on the lethality of the precursors. (Authors) 37 refs

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-11-01

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

  3. Relationship between the expression of Ku gene and radiosensitivity in nasopharyngeal carcinoma cell strains

    International Nuclear Information System (INIS)

    Objective: To elucidate the relationship between expression of Ku70/Ku80 gene (a modulating subunit of DNA-PK, which is an important component in NHEJ pathway) and radiosensitivity of nasopharyngeal carcinoma cell strains. Methods: Radiosensitivity parameters of nasophryngeal carcinoma cell strains were obtained by the colony forming assay and dose-survival curve was developed according to linear quadratic model. The two cell strains were exposed to 4 Gy of 60Co γ rays, the growth rate of cell group was obtained by MTT assay, and the different radiosensitivity of two cell strains was evaluated. The dynamical changes of the expression of Ku70 and Ku80 in mRNA level in CNE-1 and CNE-2 were detected by RT-FQ-PCR at different doses. Results: The survival rates of CNE-1 were higher than those of CNE-2 at each dose point. The mean inactivation dose was higher in CNE-1 (2.78) than that in CNE-2(1.61), and the values of SF2 was 0.627 and 0.341, respectively. After 4 Gy irradiation, the survival rate in CNE-1 was also higher than that in the CNE-2. The ratio of relative expression of Ku70 and Ku80 in the two cell strains was 1.76 ± 0.54(P=0.07) and 13.82 ± 3.78 (P=0.004), respectively. The expression of Ku80 in CNE-2 was correlated with the irradiation dose. Conclusions: CNE-2 cells are more radiosensitive than CNE-1. The expression of Ku80 gene is correlated with the radiosensitivity of nasophryngeal carcinoma cells. (authors)

  4. The role of glutathione in the radiosensitive effect induced by treating HeLa cells with sanazole

    International Nuclear Information System (INIS)

    Objective: To investigate radiosensitive effect of sanazole on HeLa cells and its relationship with glutathione (GSH). Methods: The anoxia model was made by inflow of nitrogen gas. The survival rate of HeLa cells was observed with method of colony formation after treatment with sanazole and 60Co γ irradiation. Radiosensitive effect was evaluated through measurement of sensitizing enhancement ratio (SER) resulted from single-target multi-hit model. The GSH content in these HeLa cells was determined by the tetra-oxypyrimidine UV-spectrophotometer method to explore the mechanism of radiosensitive effect. Results: SER was more than 1.4. The concentration of GSH decreased significantly with increasing concentration of sensitizer and dose of radiation, especially under anoxia condition. Conclusions: Sanazole has significant radiosensitive effect and decrease in GSH content resulted from combination with 60Co γ irradiation may be one of its radiosensitive mechanisms

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

    Directory of Open Access Journals (Sweden)

    Kim Han

    2012-07-01

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

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

    International Nuclear Information System (INIS)

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

  7. Comet-electrophoresis assay as a method for determining radiosensitivities of tumor cells

    International Nuclear Information System (INIS)

    Objective: To explore the feasibility of applying comet-electrophoresis to determining the radiosensitivity of tumor cells. Methods: The residual rates of DNA damage at 30 minute after 2 Gy gamma irradiation in four human tumor cell lines (WM9839, KB, LS-T-117, PC3M) were determined with the comet assay. The cell survival fraction of tumor cell after 2 Gy gamma ray-irradiation was determined with clonogenic assay. Results: There were good correlations between cell survival fraction (SF2 ) and residual rate of DNA damage at 30 minute after 2 Gy gamma ray-irradiation in these four human tumor cell lines, separately. Conclusion: The comet-electrophoresis assay may be used as a repaid and sensitive method for determining inherent radiosensitivities of tumor cells

  8. Radiosensitization of micro RNA-17-92 on human mantle cell lymphoma cells in vitro

    International Nuclear Information System (INIS)

    Objective: To investigate the effects of microRNA-17-92 on radiosensitivity of human mantle cell lymphoma cells. Methods: Tetracycline-regulated pRevTet-On expression system was established to generate cell line Z138c-miR-17-92 with over-expressed miR-17-92 and cell line Z138c-TMP2. Cell proliferation was measured by 3H-TdR incorporation and viable cell counting stained with typan blue. Cell cycle distribution was analysed by flow cytometry (FCM). Results: More viable and proliferous cells were counted in group miR-17-92, when exposure dose was greater than 2 Gy and incubation time was longer than 48 h under the same condition (t=-3.12 and -3.28, P2/M cell in group TMP2 was increased while no obvious cell cycle arrests were found in group miR-17-92 at 2 and 4 Gy (t=2.885, P<0.05). When cells were incubated for 96 h, higher percentage of propidium iodide (PI) positively stained cells were found in group TMP2 (24.02% vs. 36.16%) compared with group miR-17-92 (6.49% vs. 11.39%) at 2 and 4 Gy, respectively (t=-17.59, -4.972, P<0.05). Conclusions: Overexpression of microRNA-17-92 decreased the radiosensitivity of human mantle cell lymphoma cells by inhibition of cell cycle changes and cell apoptosis. (authors)

  9. Radiosensitivity of CD45RO{sup +} memory and CD45RO{sup {minus}} naive T cells in culture

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    Uzawa, Akiko; Suzuki, Gen; Nakata, Yukiko; Akashi, Makoto; Ohyama, Harumi; Akanuma, Atsuo [National Institute of Radiological Sciences, Chiba (Japan)

    1994-01-01

    Radiosensitivities of various human T-cell subsets were investigated by a proliferation assay and by a single-cell gel electrophoresis assay. Each T-cell subset was purified using a cell sorter and was induced to proliferate by ionomycin and interleukin 2. Unsorted T cells showed biphasic dose-survival curves, indicating the heterogeneity of T cells in terms of radiosensitivity. Purified CD4{sup +} helper and CD8{sup +} killer T cells showed similar biphasic dose-survival curves. Hence both T-cell subsets were composed of cells of different radiosensitivity. The T-cell subsets belonging to different activation stages such as CD45RO{sup +} memory and CD45RO{sup {minus}} naive T cells had different dose-survival curves. The former was more radiosensitive than the latter. The high radiosensitivity of CD45RO{sup +} cells was also demonstrated by single-cell gel electrophoresis after irradiation. This is the first demonstration that a particular cell surface marker on T cells is correlated with greater radiosensitivity. 27 refs., 7 figs., 1 tab.

  10. Induction during G1 of heat radiosensitization in Chinese hamster ovary cells following single and fractionated heat doses

    International Nuclear Information System (INIS)

    When G1 Chinese hamster ovary cells were heated at 42.2 degrees C and X-irradiated, heat radiosensitization increased slightly with cell killing. However, when thermo-tolerance was allowed to develop by continuous heating for periods longer than 4 hours, which reduces survival to 0.18, heat radiosensitization no longer increased with continued heating or cell killing. When cells were heated with single doses at 45.5 degrees C, heat radiosensitization increased as a function of heat killing. However, if acute heat doses at 45.5 degrees C were fractionated and cells incubated for 10 hours at 37 degrees C between fractions, significant tolerance to heat radiosensitization was observed. For example, heating cells at 45.5 degrees C for 15 minutes reduced survival to 0.40 and decreased the D0 to 0.45 gray, whereas 2 fractionated 15-minute doses at 45.5 degrees C, separated by 10 hours at 37 degrees C, resulted in a D0 of 0.65 gray. Thus if heat killing increased without the development of thermotolerance, heat radiosensitization also increased continually, whereas when thermotolerance developed after continuous or fractionated heating without cell progression, some tolerance to continued heat radiosensitization also was observed. This tolerance to both heat killing and heat radiosensitization indicates that both involve similar target(s)

  11. The effects of acetaminophen combine with radiation on the radiosensitivity of filial generation from irradiated human glioma cell line

    International Nuclear Information System (INIS)

    Objective: To study the effects of acetaminophen (ACE) combined with radiation on the filial generation from irradiated human glioma cell line SHG-44 in vitro and to investigate if ACE may prove to be a useful therapeutic agent and be radiosensitive in the treatment of recurrent human glioma. Methods: The SHG-44 cells were irradiated with 6MV X ray and the progeny of the cells were cultured (SHG-44-10 cell line). The population doubling time (PDT) was detected pre-and post-irradiation. The culture of the progeny of irradiated human glioma cell line SHG-44 was treated with ACE to do the radiosensitive experiment. ACE's radiosensitivity was measured by clone forming assay. The cell cycle distribution was analyzed by flow cytometry (FCM). Results: Comparing with SHG-44 cells it was found that growth delay and declined radiosensitivity were confirmed in SHG-44-10 cell after irradiation, but if they were treated with ACE, the radiosensitivity increased. To SHG-44-10 cell, after 12 h irradiation, the percentages of the G2/M phase cells were significantly increased, and then decreased rapidly after treatment ACE for 24 h. While the percentage in the group in which SHG-44 cells were treated with ACE still maintained in high level. Conclusion: (1) In the present study, growth delay and declined radiosensitivity are confirmed in the progeny of irradiated SHG-44 cells. (2)Subtoxic dose of ACE increased the radiosensitivity of the progeny of irradiated human glioma cell line SHG-44. The mechanism may be that the SHG-44 cells were blocked in the G2/M phase of the cell cycle and induce cells apoptosis. (3) ACE may be an useful radiosensitivity in the treatment of recrudescent human malignant glioma. (authors)

  12. DNA polymerase activity in heat killing and hyperthermic radiosensitization of mammalian cells as observed after fractionated heat treatments.

    Science.gov (United States)

    Jorritsma, J B; Burgman, P; Kampinga, H H; Konings, A W

    1986-03-01

    Possible relations between hyperthermic inactivation of alpha and beta DNA polymerase activity and hyperthermic cell killing or hyperthermic radiosensitization were investigated. Ehrlich Ascites Tumor (EAT) cells and HeLa S3 cells were treated with fractionated doses of hyperthermia. The heating schedules were chosen such that the initial heat treatment resulted in either thermotolerance or thermosensitization (step-down heating) for the second heat treatment. The results show that for DNA polymerase activity and heat radiosensitization (cell survival) no thermotolerance or thermosensitization is observed. Thus hyperthermic cell killing and DNA polymerase activity are not correlated. The correlation of hyperthermic radiosensitization and DNA polymerase activity was substantially less than observed in previous experiments with normotolerant and thermotolerant HeLa S3 cells. We conclude that alpha and beta DNA polymerase inactivation is not always the critical cellular process responsible for hyperthermic cell killing or hyperthermic radiosensitization. Other possible cellular systems that might determine these processes are discussed. PMID:3754338

  13. DNA polymerase activity in heat killing and hyperthermic radiosensitization of mammalian cells as observed after fractionated heat treatments

    Energy Technology Data Exchange (ETDEWEB)

    Jorritsma, J.B.; Burgman, P.; Kampinga, H.H.; Konings, A.W.

    1986-03-01

    Possible relations between hyperthermic inactivation of alpha and beta DNA polymerase activity and hyperthermic cell killing or hyperthermic radiosensitization were investigated. Ehrlich Ascites Tumor (EAT) cells and HeLa S3 cells were treated with fractionated doses of hyperthermia. The heating schedules were chosen such that the initial heat treatment resulted in either thermotolerance or thermosensitization (step-down heating) for the second heat treatment. The results show that for DNA polymerase activity and heat radiosensitization (cell survival) no thermotolerance or thermosensitization is observed. Thus hyperthermic cell killing and DNA polymerase activity are not correlated. The correlation of hyperthermic radiosensitization and DNA polymerase activity was substantially less than observed in previous experiments with normotolerant and thermotolerant HeLa S3 cells. We conclude that alpha and beta DNA polymerase inactivation is not always the critical cellular process responsible for hyperthermic cell killing or hyperthermic radiosensitization. Other possible cellular systems that might determine these processes are discussed.

  14. HAP1 gene expression is associated with radiosensitivity in breast cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jing [The Fourth Clinical School of Nanjing Medical University, Nanjing, Jiangsu (China); Department of Radiation Oncology, Nanjing Medical University Affiliated Cancer Hospital, Cancer Institute of Jiangsu Province, Nanjing, Jiangsu (China); Zhang, Jun-ying [Research Center of Clinical Oncology, Nanjing Medical University Affiliated Cancer Hospital, Cancer Institute of Jiangsu Province, Nanjing, Jiangsu (China); Yin, Li [Department of Radiation Oncology, Nanjing Medical University Affiliated Cancer Hospital, Cancer Institute of Jiangsu Province, Nanjing, Jiangsu (China); Research Center of Clinical Oncology, Nanjing Medical University Affiliated Cancer Hospital, Cancer Institute of Jiangsu Province, Nanjing, Jiangsu (China); Wu, Jian-zhong [Research Center of Clinical Oncology, Nanjing Medical University Affiliated Cancer Hospital, Cancer Institute of Jiangsu Province, Nanjing, Jiangsu (China); Guo, Wen-jie; Wu, Jian-feng [Department of Radiation Oncology, Nanjing Medical University Affiliated Cancer Hospital, Cancer Institute of Jiangsu Province, Nanjing, Jiangsu (China); Chen, Meng; Xia, You-you [The Fourth Clinical School of Nanjing Medical University, Nanjing, Jiangsu (China); Department of Radiation Oncology, Nanjing Medical University Affiliated Cancer Hospital, Cancer Institute of Jiangsu Province, Nanjing, Jiangsu (China); Tang, Jin-hai [Department of General Surgery, Nanjing Medical University Affiliated Cancer Hospital, Cancer Institute of Jiangsu Province, Nanjing, Jiangsu (China); Ma, Yong-chao [Department of Hematology, First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu (China); He, Xia, E-mail: hexiadoctor@163.com [Department of Radiation Oncology, Nanjing Medical University Affiliated Cancer Hospital, Cancer Institute of Jiangsu Province, Nanjing, Jiangsu (China)

    2015-01-02

    Highlights: • Overexpression of HAP1 gene promotes apoptosis in MCF-7 cells after irradiation. • HAP1 reduces tumor volume in nude mice xenograft models after irradiation. • HAP1 increases radiosensitivity of breast cancer cells in vitro and vivo. - Abstract: Objectives: The purpose of this study was to investigate the relationship between huntingtin-associated protein1 (HAP1) gene and radiation therapy of breast cancer cells. Methods: HAP1 gene was transfected into breast cancer MCF-7 cells, which was confirmed by quantitative reverse transcription-polymerase chain reaction analysis (qRT-PCR) and Western blot in vitro. The changes of cell radiosensitivity were assessed by colony formation assay. Apoptosis were examined by flow cytometry. The expressions of two radiation-induced genes were evaluated by Western blot. Tumor growth was investigated in nude mice xenograft models in vivo. Results: Our data showed that HAP1 gene expression was significantly increased in HAP1-transfected MCF-7 cells in comparison with the parental cells or negative control cells. The survival rate in MCF-7/HAP1 cells was significantly decreased after irradiation (0, 2, 4, 6, 8 Gy), compared to cells in MCF-7 and MCF-7/Pb groups in vitro. HAP1 gene increased apoptosis in MCF-7 cells after irradiation. Additionally, the tumor volume and weight in MCF-7/HAP1 + RT group were observably lower than in MCF-7/HAP1 group and MCF-7/Pb + RT group. Conclusion: The present study indicated that HAP1 gene expression was related to the radiosensitivity of breast cancer cells and may play an important role in the regulation of cellular radiosensitivity.

  15. HAP1 gene expression is associated with radiosensitivity in breast cancer cells

    International Nuclear Information System (INIS)

    Highlights: • Overexpression of HAP1 gene promotes apoptosis in MCF-7 cells after irradiation. • HAP1 reduces tumor volume in nude mice xenograft models after irradiation. • HAP1 increases radiosensitivity of breast cancer cells in vitro and vivo. - Abstract: Objectives: The purpose of this study was to investigate the relationship between huntingtin-associated protein1 (HAP1) gene and radiation therapy of breast cancer cells. Methods: HAP1 gene was transfected into breast cancer MCF-7 cells, which was confirmed by quantitative reverse transcription-polymerase chain reaction analysis (qRT-PCR) and Western blot in vitro. The changes of cell radiosensitivity were assessed by colony formation assay. Apoptosis were examined by flow cytometry. The expressions of two radiation-induced genes were evaluated by Western blot. Tumor growth was investigated in nude mice xenograft models in vivo. Results: Our data showed that HAP1 gene expression was significantly increased in HAP1-transfected MCF-7 cells in comparison with the parental cells or negative control cells. The survival rate in MCF-7/HAP1 cells was significantly decreased after irradiation (0, 2, 4, 6, 8 Gy), compared to cells in MCF-7 and MCF-7/Pb groups in vitro. HAP1 gene increased apoptosis in MCF-7 cells after irradiation. Additionally, the tumor volume and weight in MCF-7/HAP1 + RT group were observably lower than in MCF-7/HAP1 group and MCF-7/Pb + RT group. Conclusion: The present study indicated that HAP1 gene expression was related to the radiosensitivity of breast cancer cells and may play an important role in the regulation of cellular radiosensitivity

  16. Mitochondrial modulation of oxygen-dependent radiosensitivity in some human tumour cell lines.

    LENUS (Irish Health Repository)

    Anoopkumar-Dukie, S

    2009-10-01

    Oxygen-dependent radiosensitivity of tumour cells reflects direct oxidative damage to DNA, but non-nuclear mechanisms including signalling pathways may also contribute. Mitochondria are likely candidates because not only do they integrate signals from each of the main kinase pathways but mitochondrial kinases responsive to oxidative stress communicate to the rest of the cell. Using pharmacological and immunochemical methods, we tested the role of mitochondrial permeability transition (MPT) and the Bcl-2 proteins in oxygen-dependent radiosensitivity. Drug-treated or untreated cervical cancer HeLa, breast cancer MCF-7 and melanoma MeWo cell lines were irradiated at 6.2 Gy under normoxic and hypoxic conditions then allowed to proliferate for 7 days. The MPT blocker cyclosporin A (2 microM) strongly protected HeLa but not the other two lines against oxygen-dependent radiosensitivity. By contrast, bongkrekic acid (50 microM), which blocks MPT by targeting the adenine nucleotide transporter, had only marginal effect and calcineurin inhibitor FK-506 (0.1 microM) had none. Nor was evidence found for the modulation of oxygen-dependent radiosensitivity by Bax\\/Bcl-2 signalling, mitochondrial ATP-dependent potassium (mitoK(ATP)) channels or mitochondrial Ca(2+) uptake. In conclusion, calcineurin-independent protection by cyclosporin A suggests that MPT but not mitoK(ATP) or the mitochondrial apoptosis pathway plays a causal role in oxygen-dependent radiosensitivity of HeLa cells. Targeting MPT may therefore improve the effectiveness of radiotherapy in some solid tumours.

  17. Radiosensitizing effect of 2,4-dinitroimidazole-1-ethanol and its cytotoxicity in HeLa S3 cells

    International Nuclear Information System (INIS)

    Using cultured HeLa S3 cells, the radiosensitizing and cytotoxic effects of newly synthesized derivatives of dinitroimidazole were investigated and compared with those of misonidazole. 2,4-dinitroimidazole-1-ethanol radiosensitized hypoxic cells selectively. At 5 mM misonidazole, the enhancement ratio was 1.95; with 0.5 mM 2,4-dinitroimidazole-1-ethanol, almost the same enhancement could be obtained. This indicates that the radiosensitizing effect of the latter agent was about 10 times greater than that of misonidazole. However, its cytotoxicity was twice that of misonidazole under hypoxic conditions and there was no apparent differential cytotoxicity to hypoxic and aerobic cells. (orig.)

  18. Cytosine Deaminase/5-Fluorocytosine Exposure Induces Bystander and Radiosensitization Effects in Hypoxic Glioblastoma Cells in vitro

    International Nuclear Information System (INIS)

    Purpose: Treatment of glioblastoma (GBM) is limited by therapeutic ratio; therefore, successful therapy must be specifically cytotoxic to cancer cells. Hypoxic cells are ubiquitous in GBM, and resistant to radiation and chemotherapy, and, thus, are logical targets for gene therapy. In this study, we investigated whether cytosine deaminase (CD)/5-fluorocytosine (5-FC) enzyme/prodrug treatment induced a bystander effect (BE) and/or radiosensitization in hypoxic GBM cells. Methods and Materials: We stably transfected cells with a gene construct consisting of the SV40 minimal promoter, nine copies of a hypoxia-responsive element, and the yeast CD gene. During hypoxia, a hypoxia-responsive element regulates expression of the CD gene and facilitates the conversion of 5-FC to 5-fluorouracil, a highly toxic antimetabolite. We used colony-forming efficiency (CFE) and immunofluorescence assays to assess for BE in co-cultures of CD-expressing clone cells and parent, pNeo- or green fluorescent protein-stably transfected GBM cells. We also investigated the radiosensitivity of CD clone cells treated with 5-FC under hypoxic conditions, and we used flow cytometry to investigate treatment-induced cell cycle changes. Results: Both a large BE and radiosensitization occurred in GBM cells under hypoxic conditions. The magnitude of the BE depended on the number of transfected cells producing CD, the functionality of the CD, the administered concentration of 5-FC, and the sensitivity of cell type to 5-fluorouracil. Conclusion: Hypoxia-inducible CD/5-FC therapy in combination with radiation therapy shows both a pronounced BE and a radiosensitizing effect under hypoxic conditions

  19. Enhancement of human glioma cells SHG44 radiosensitivity with celecoxib in vitro studies

    International Nuclear Information System (INIS)

    In order to understand the radiosensitizing effects on human glioma cells SHG44 using celecoxib, a cyclooxygenase (COX)-2 selective inhibitor, MTT assay was used to determine the effect of celecoxib on the cell growth, and Colony Formation assay, Reverse transcription-PCR assay were used to investigate the effect of celecoxib or combined with 60Co γ-irradiation on cell colony formation rate and the levels of COX-2 mRNA expression. Experimental results suggested that the cytotoxicity of celecoxib enhanced along with the increment of drug's concentration. The celecoxib could inhibit colony formation in SHG44 cells. When combined with 60Co γ-irradiation, COX-2 mRNA expression levels was lower than that of control, drug and irradiation group respectively. The study confirmed the radiosensitizing effects of this drug to human glioma cells SHG44, and it might be closely related to the COX-2 mRNA expression levels. (authors)

  20. The relationship of DNA double-strand break induction to radiosensitivity in human tumour cell lines

    International Nuclear Information System (INIS)

    Recent data suggest that differences in radiosensitivity between cell lines can be related to differences in dsb induction (Radford 1986). The current authors set out to assess the extent to which differences in radiation survival between nine human tumour cell lines could be attributed to differences in dsb induction. The lines varied widely in sensitivity, ranging from a sensitive neuroblastoma (surviving fraction at 2 Gy, SF2 = 0.13) to a resistant bladder carcinoma (SF2 = 0.62). Dsb induction was found to vary between the cell lines, such that resistant cells generally suffered less damage than sensitive ones. The data suggest that, in human tumour cell lines, differences in radiosensitivity may at least in part be due to different levels of damage induction, but that some lines may vary in their tolerance of damage due to differences in biological characteristics such as repair capacity. (author)

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

    International Nuclear Information System (INIS)

    Objective: To explore the radiosensitization effect of thalidomide combined with X-ray on esophageal carcinoma TE1 cells. Methods: Cell scratch assay was used to detect the inhibition ability of different concentration of Thalidomide on cell invasion and metastasis. H3-TdR incorporation assay was used to investigate the inhibition of DNA synthesis in TE1 cells by treated with Thalidomide singly or combination with X-rays. The colony formation assay was used to analyze the radiosensitization of Thalidomide effect on TE1 cells. Results: Thalidomide had obvious inhibition effect on TE1 cell metastasis, DNA synthesis and colony formation, which were correlated with drug concentration. The values D0, Dq and SF2 in TE1 cells were gradually decreased with thalidomide concentration increased. When the concentration of thalidomide was 100μg/ml, the SERD0 and SERD0 and SERDq were (1.4±0.2) and (1.5±0.1), respectively, While the concentration of thalidomide was 150 μg/ml, the SERD0 and SERDq were (1.5±0.2) and (1.8±0.2), respectively. Conclusions: Thalidomide could inhibit TE1 cell invasion, metastasis, DNA synthesis, and significantly enhance the radiosensitizing effect on esophageal carcinoma TE1 cells. (authors)

  2. Radiosensitization of Oropharyngeal Squamous Cell Carcinoma Cells by Human Papillomavirus 16 Oncoprotein E6*I

    International Nuclear Information System (INIS)

    Purpose: Patients with oropharyngeal squamous cell carcinoma (OSCC) whose disease is associated with high-risk human papillomavirus (HPV) infection have a significantly better outcome than those with HPV-negative disease, but the reasons for the better outcome are not known. We postulated that they might relate to an ability of HPV proteins to confer a better response to radiotherapy, a commonly used treatment for OSCC. Methods and Materials: We stably expressed the specific splicing-derived isoforms, E6*I and E6*II, or the entire E6 open reading frame (E6total), which gives rise to both full length and E6*I isoforms, in OSCC cell lines. Radiation resistance was measured in clonogenicity assays, p53 activity was measured using transfected reporter genes, and flow cytometry was used to analyze cell cycle and apoptosis. Results: E6*I and E6total sensitized the OSCC cells to irradiation, E6*I giving the greatest degree of radiosensitization (approximately eightfold lower surviving cell fraction at 10 Gy), whereas E6*II had no effect. In contrast to radiosensitivity, E6*I was a weaker inhibitor than E6total of tumor suppressor p53 transactivator activity in the same cells. Flow cytometric analyses showed that irradiated E6*I expressing cells had a much higher G2M:G1 ratio than control cells, indicating that, after G2, cells were diverted from the cell cycle to programmed cell death. Conclusion: This study supports a role for E6*I in the enhanced responsiveness of HPV-positive oropharyngeal carcinomas to p53-independent radiation-induced death.

  3. Radiosensitivity of marrow stromal cells and the effect of some radioprotective agents

    International Nuclear Information System (INIS)

    The results showed that marrow stromal cells include fibroblasts, reticular cells, macrophages and adipocytes. The capability of the adherent layer derived from marrow cells of 2 mouse femurs to support hematopoietic stem cells was stronger than those of layers derived from 0.5 or 1 mouse femurs. The radiosensitivity of bone marrow stromal cells was lower than that of hematopoietic stem cells. The radioprotective effect of AET and PLP (polysaccharide of Lobaria Pulmonaria Hoffm) on the bone marrow stromal cells and their capability to support hematopoietic stem cells was clearly demonstrated

  4. EGFR-dependent Impact of Indol-3-Carbinol on Radiosensitivity 
of Lung Cancer Cells

    Directory of Open Access Journals (Sweden)

    Xiao XIAO

    2012-07-01

    Full Text Available Background and objective Indole-3-carbinol (I3C is a naturally occurring phytochemical found in cruciferous vegetables. The aim of the present study is to investigate the influence of I3C on radiosensitivity in epidermal growth factor receptor (EGFR-positive and EGFR-negative lung cancer cell lines. Methods Human lung adenocarcinoma NIH-H1975 cells and human lung squamous carcinoma NIH-H226 and NIH-H520 cells were routinely cultured in RPMI-1640. MTT assay and clonogenic assay were used to detect cell growth and survival, respectively. Western blot and RT-PRC assay was employed to detect EGFR protein and mRNA expression. Results 5 μmol/L of I3C significantly reduced radiosensitivity of EGFR-positive NIH-H1975 and NIH-H226 cells, but failed to affect radiosensitivity of EGFR-negative NIH-H520 cells. Furthermore, I3C caused an increased expression of total EGFR and pEGFR (Y845 protein in NIH-H1975 and NIH-H226 cell lines, but not in NIH-H520 cell line. A reduction of EGFR expression by EGFR-siRNA significantly inhibited I3C-caused radioresistance in NIH-H1975 cells. Conclusion Our data presented here for the first time demonstrate that I3C reduces radiosensitivity of lung cancer cells by mediating EGFR expression, indicating that EGFR may be an important target for I3C-mediated radioresistance in lung cancer.

  5. Zidovudine, abacavir and lamivudine increase the radiosensitivity of human esophageal squamous cancer cell lines.

    Science.gov (United States)

    Chen, Xuan; Wang, Cong; Guan, Shanghui; Liu, Yuan; Han, Lihui; Cheng, Yufeng

    2016-07-01

    Telomerase is a type of reverse transcriptase that is overexpressed in almost all human tumor cells, but not in normal tissues, which provides an opportunity for radiosensitization targeting telomerase. Zidovudine, abacavir and lamivudine are reverse transcriptase inhibitors that have been applied in clinical practice for several years. We sought to explore the radiosensitization effect of these three drugs on human esophageal cancer cell lines. Eca109 and Eca9706 cells were treated with zidovudine, abacavir and lamivudine for 48 h before irradiation was administered. Samples were collected 1 h after irradiation. Clonal efficiency assay was used to evaluate the effect of the combination of these drugs with radiation doses of 2, 4, 6 and 8 Gy. DNA damage was measured by comet assay. Telomerase activity (TA) and relative telomere length (TL) were detected and evaluated by real-time PCR. Apoptosis rates were assessed by flow cytometric analysis. The results showed that all the drugs tested sensitized the esophageal squamous cell carcinoma (ESCC) cell lines to radiation through an increase in radiation-induced DNA damage and cell apoptosis, deregulation of TA and decreasing the shortened TL caused by radiation. Each of the drugs investigated (zidovudine, abacavir and lamivudine) could be used for sensitizing human esophageal cancer cell lines to radiation. Consequently, the present study supports the potential of these three drugs as therapeutic agents for the radiosensitization of esophageal squamous cell cancer. PMID:27220342

  6. MicroRNA-449a enhances radiosensitivity in CL1-0 lung adenocarcinoma cells.

    Directory of Open Access Journals (Sweden)

    Yi-Jyun Liu

    Full Text Available Lung cancer is the leading cause of cancer-related mortality worldwide. Radiotherapy is often applied for treating lung cancer, but it often fails because of the relative non-susceptibility of lung cancer cells to radiation. MicroRNAs (miRNAs have been reported to modulate the radiosensitivity of lung cancer cells and have the potential to improve the efficacy of radiotherapy. The purpose of this study was to identify a miRNA that can adjust radiosensitivity in lung adenocarcinoma cells. Two lung adenocarcinoma cell lines (CL1-0 and CL1-5 with different metastatic ability and radiosensitivity were used. In order to understand the regulatory mechanisms of differential radiosensitivity in these isogenic tumor cells, both CL1-0 and CL1-5 were treated with 10 Gy radiation, and were harvested respectively at 0, 1, 4, and 24 h after radiation exposure. The changes in expression of miRNA upon irradiation were examined using Illumina Human microRNA BeadChips. Twenty-six miRNAs were identified as having differential expression post-irradiation in CL1-0 or CL1-5 cells. Among these miRNAs, miR-449a, which was down-regulated in CL1-0 cells at 24 h after irradiation, was chosen for further investigation. Overexpression of miR-449a in CL1-0 cells effectively increased irradiation-induced DNA damage and apoptosis, altered the cell cycle distribution and eventually led to sensitization of CL1-0 to irradiation.

  7. Effect of etanidazole-loaded nanoparticles on radiosensitization of hypoxic tumor cells

    International Nuclear Information System (INIS)

    Objective: To prepare active and controlled etanidazole-loaded nanoparticles and to determine the ability to radiosensitize hypoxie human breast carcinoma cells (MCF-7) and human carcinoma cervices cells (HeLa). Methods: The poly (D, L-lactide-co-glycolide)(PLGA) nanoparticles containing etanidazole were prepared by w/o/w emulsification-solvent evaporation method. The drug loading efficiency, the encapsulation efficiency (EE) and the release profile in vitro were measured by high-performance liquid chromatography. The morphology of the etanidazole-loaded nanoparticles was investigated by transmission electron microscope. The size distribution of nanoparticles was determined by laser diffraction analyzer. Cell viability was measured by the ability of single cell to form colonies in vitro. Results: The prepared nanoparticles were spherical in shape with sizes between 90 and 190 nm. The drug loading efficiency and EE was 1.66% and 18.02%, respectively. The drug release pattern was biphasic with a fast release rate followed by a slow one. Co- culture of hypoxic MCF-7 and HeLa cells with etanidazole-loaded nanoparticles and free etanidazole demonstrated that released etanidazole effectively sensitized hypoxic tumor cells to irradiation. Compared with free etanidazole, radiosensitization of etanidazole-loaded nanoparticles was more significant. Conclusions: It is demonstrated that etanidazole can be effectively released from a biodegradable PLGA nanoparticle delivery system while maintaining potent radiosensitizing ability for hypoxic tumor cells. (authors)

  8. Increased betulinic acid induced cytotoxicity and radiosensitivity in glioma cells under hypoxic conditions

    Directory of Open Access Journals (Sweden)

    Paschke Reinhard

    2011-09-01

    Full Text Available Abstract Background Betulinic acid (BA is a novel antineoplastic agent under evaluation for tumor therapy. Because of the selective cytotoxic effects of BA in tumor cells (including gliomas, the combination of this agent with conservative therapies (such as radiotherapy and chemotherapy may be useful. Previously, the combination of BA with irradiation under hypoxic conditions had never been studied. Methods In this study, the effects of 3 to 30 μM BA on cytotoxicity, migration, the protein expression of PARP, survivin and HIF-1α, as well as radiosensitivity under normoxic and hypoxic conditions were analyzed in the human malignant glioma cell lines U251MG and U343MG. Cytotoxicity and radiosensitivity were analyzed with clonogenic survival assays, migration was analyzed with Boyden chamber assays (or scratch assays and protein expression was examined with Western blot analyses. Results Under normoxic conditions, a half maximal inhibitory concentration (IC50 of 23 μM was observed in U251MG cells and 24 μM was observed in U343MG cells. Under hypoxic conditions, 10 μM or 15 μM of BA showed a significantly increased cytotoxicity in U251MG cells (p = 0.004 and p = 0.01, respectively and U343MG cells (p Conclusion Our results suggest that BA is capable of improving the effects of tumor therapy in human malignant glioma cells, particularly under hypoxic conditions. Further investigations are necessary to characterize its potential as a radiosensitizer.

  9. Radiosensitization of non-small cell lung carcinoma by EGFR inhibition

    Directory of Open Access Journals (Sweden)

    Keta Otilija D.

    2014-01-01

    Full Text Available Molecular targeted cancer therapy is a promising treatment strategy. Considering the central role of the epidermal growth factor receptor in cell proliferation and survival, there are indications that targeted agents like tyrosine kinase inhibitors, i. e., erlotinib, may enhance the antitumor treatment by radiation. The aim of this study is to analyze the inactivation effects of g-rays and to test the radiosensitizing potential of erlotinib on human lung adenocarcinoma cells in vitro. Irradiations were performed with doses ranging from 1 Gy to 8 Gy. In order to increase the radiosensitivity of CRL-5876 lung adenocarcinoma cells, the cells were treated with a clinically relevant concentration of 2 µM erlotinib. The effects of single and combined treatments were monitored using clonogenic survival, cell viability and proliferation assays at different time points. For the detection and visualization of the phosphorylated histone H2AX (γ-H2AX, an important biological marker of DNA double-strand break formation, fluorescence immunocytochemistry, was performed. The response to the treatment was monitored at four time points: 30 min, 2, 6, and 24 h. Irradiations with g-rays resulted in significant cell inactivation regarding all analyzed biological endpoints. Combined treatments revealed consistent cell inactivation. Moreover, compared to g-rays alone, elevated levels of g-H2AX foci were observed after pretreatment with erlotinib, indicating radiosensitization through impaired DNA repair. [Projekat Ministarstva nauke Republike Srbije, br. 173046 i br. 171019

  10. Radiosensitizing and cytotoxic effects of hyperthermia on various biological systems. Radiosensitizing and cytotoxic effect of hyperthermia on mouse leukosis La cells

    Energy Technology Data Exchange (ETDEWEB)

    Shtejn, L.V.; Konoplyannikov, A.G. (Akademiya Meditsinskikh Nauk SSSR, Obninsk. Nauchno-Issledovatel' skij Inst. Meditsinskoj Radiologii)

    When mouse leukosis cell suspensions were subjected to heating the survival rate of animals decreased exponentially with increasing time of heating. It is shown that the increase of temperature for 1 deg C in range 40-45 deg C was equivalent to a decrease in the heating time by a factor of approximately 2. The hyperthermia-induced increase in the radiosensitivity of leukosis cells was dependent upon a medium in which heating was performed.

  11. Radiosensitivity of Ehrlich ascites tumor clonogenic cells forming colonies in agar cultures in diffuse chambers

    International Nuclear Information System (INIS)

    A study was made of the dependence of survival of Ehrlich ascites tumor clonogenic cells on the 3d and 7th days following inoculation upon radiation dose (60Co-γ-rays) delivered under well oxygenated in vitro conditions. No differences were detected in radiosensitivity of 3- and 7-day Ehrlich ascites tumor cells: in both cases, the ''dose - effect'' curves were S-shaped with a small shoulder and close D0 values

  12. Simulation on the molecular radiosensitization effect of gold nanoparticles in cells irradiated by x-rays

    International Nuclear Information System (INIS)

    Abundant studies have focused on the radiosensitization effect of gold nanoparticles (GNPs) in the cellular environment with x-ray irradiation. To better understand the physical foundation and to initially study the molecular radiosensitization effect within the nucleus, a simple cell model with detailed DNA structure in the central nucleus was set up and complemented with different distributions of single and multiple GNPs in this work. With the biophysical Monte Carlo simulation code PARTRAC, the radiosensitization effects on both physical quantities and primary biological responses (DNA strand breaks) were simulated. The ratios of results under situations with GNPs compared to those without GNPs were defined as the enhancement factors (EFs). The simulation results show that the presence of GNP can cause a notable enhancement effect on the energy deposition within a few micrometers from the border of GNP. The greatest upshot appears around the border and is mostly dominated by Auger electrons. The enhancement effect on the DNA strand breakage becomes smaller because of the DNA distribution inside the nucleus, and the corresponding EFs are between 1 and 1.5. In the present simulation, multiple GNPs on the nucleus surface, the 60 kVp x-ray spectrum and the diameter of 100 nm are relatively more effective conditions for both physical and biological radiosensitization effects. These results preliminarily indicate that GNP can be a good radiosensitizer in x-ray radiotherapy. Nevertheless, further biological responses (repair process, cell survival, etc) need to be studied to give more accurate evaluation and practical proposal on GNP’s application in clinical treatment. (paper)

  13. Telomere loss, not average telomere length, confers radiosensitivity to TK6-irradiated cells

    Energy Technology Data Exchange (ETDEWEB)

    Berardinelli, F.; Nieri, D.; Sgura, A.; Tanzarella, C. [Dip. Di Biologia, Università “Roma Tre”, Rome (Italy); INFN – “Roma Tre”, Rome (Italy); Antoccia, A., E-mail: antoccia@uniroma3.it [Dip. Di Biologia, Università “Roma Tre”, Rome (Italy); INFN – “Roma Tre”, Rome (Italy)

    2012-12-15

    Highlights: ► Ionizing radiation induced telomere lengthening in TK6 clones from a single cell. ► Telomerase is not involved in the telomere lengthening observed. ► TK6 cells display very heterogeneous values in telomere length and telomere loss. ► A selective process account for telomere lengthening in irradiated cells. ► Telomere loss, not mean telomere length, is predictive of radiosensitivity. - Abstract: Many and varied are the proposed mechanisms that lead to resistance to ionizing radiation treatment. Among them, an inverse relationship between telomere length and radioresistance has been recently advanced. Investigating such a relationship in TK6 lymphoblasts, we found that clones originating from cells survived to 4 Gy of X-rays showed a significantly higher telomere length when compared with clones grown from untreated cells. The lengthening observed was not attributable to a radiation-induced increase in telomerase activity, as demonstrated by TRAP assay performed in the dose range of 1–10 Gy. Given the evidence that TK6 whole population was characterized by heterogeneity in cellular mean telomere length and telomere loss, we tested the hypothesis that a process of selection may favour cells with longer telomeres (more radioresistant cells) following exposure to irradiation. In order to do this 15 independent TK6 clones were selected and characterized for telomere length and loss on the basis of q-FISH and flow-FISH analysis. Among the screened clones four characterized by long telomeres and four characterized by short telomeres were tested for their radiosensitivity by means of clonogenic assay. The results obtained showed that, in our experimental conditions (cellular model, radiation doses) no significant correlation was observed between radiosensitivity and mean telomere lengths, whereas a positive correlation was observed with respect to telomere loss. Overall, these results indicate that telomere loss and not mean telomere length plays

  14. Radiosensitivity and thermosensitization of thermotolerant Chinese hamster cells and RIF-1 tumors

    International Nuclear Information System (INIS)

    CHO cells subline HA-1 were made thermotolerant by a priming heat treatment(430C, 30 min). Later, 4, 16, or 24 hr, they were either irradiated or heated (430C, 30 min) and irradiated. Thermotolerance had no effect on the radiation sensitivity of the cells as measured by the D0 value of the clonogenic survival curve. However the N value of the curve (width of shoulder) showed a significant increase at 24 hr, indicating an increased capacity to accumulate sublethal damage. The same priming treatment was given to RIF-1 tumors growing in C3H mice. Later, 24 hr, when the tumors were either irradiated or heated (430C, 30 min) and irradiated, it was found that thermotolerance had no effect on the radiosensitivity of the cells as measured by in vitro assay. However, thermal radiosensitization was not apparent 24 hr after the priming treatment

  15. Radioprotection and Cell Cycle Arrest of Intestinal Epithelial Cells by Darinaparsin, a Tumor Radiosensitizer

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Junqiang; Doi, Hiroshi [Department of Radiation Oncology, School of Medicine, Stanford University, Stanford, California (United States); Saar, Matthias; Santos, Jennifer [Department of Urology, School of Medicine, Stanford University, Stanford, California (United States); Li, Xuejun; Peehl, Donna M. [Department of Radiation Oncology, School of Medicine, Stanford University, Stanford, California (United States); Knox, Susan J., E-mail: sknox@stanford.edu [Department of Radiation Oncology, School of Medicine, Stanford University, Stanford, California (United States)

    2013-12-01

    Purpose: It was recently reported that the organic arsenic compound darinaparsin (DPS) is a cytotoxin and radiosensitizer of tumor cells in vitro and in subcutaneous xenograft tumors. Surprisingly, it was also found that DPS protects normal intestinal crypt epithelial cells (CECs) from clonogenic death after ionizing radiation (IR). Here we tested the DPS radiosensitizing effect in a clinically relevant model of prostate cancer and explored the radioprotective effect and mechanism of DPS on CECs. Methods and Materials: The radiation modification effect of DPS was tested in a mouse model of orthotopic xenograft prostate cancer and of IR-induced acute gastrointestinal syndrome. The effect of DPS on CEC DNA damage and DNA damage responses was determined by immunohistochemistry. Results: In the mouse model of IR-induced gastrointestinal syndrome, DPS treatment before IR accelerated recovery from body weight loss and increased animal survival. DPS decreased post-IR DNA damage and cell death, suggesting that the radioprotective effect was mediated by enhanced DNA damage repair. Shortly after DPS injection, significant cell cycle arrest was observed in CECs at both G1/S and G2/M checkpoints, which was accompanied by the activation of cell cycle inhibitors p21 and growth arrest and DNA-damage-inducible protein 45 alpha (GADD45A). Further investigation revealed that DPS activated ataxia telangiectasia mutated (ATM), an important inducer of DNA damage repair and cell cycle arrest. Conclusions: DPS selectively radioprotected normal intestinal CECs and sensitized prostate cancer cells in a clinically relevant model. This effect may be, at least in part, mediated by DNA damage response activation and has the potential to significantly increase the therapeutic index of radiation therapy.

  16. Radioprotection and Cell Cycle Arrest of Intestinal Epithelial Cells by Darinaparsin, a Tumor Radiosensitizer

    International Nuclear Information System (INIS)

    Purpose: It was recently reported that the organic arsenic compound darinaparsin (DPS) is a cytotoxin and radiosensitizer of tumor cells in vitro and in subcutaneous xenograft tumors. Surprisingly, it was also found that DPS protects normal intestinal crypt epithelial cells (CECs) from clonogenic death after ionizing radiation (IR). Here we tested the DPS radiosensitizing effect in a clinically relevant model of prostate cancer and explored the radioprotective effect and mechanism of DPS on CECs. Methods and Materials: The radiation modification effect of DPS was tested in a mouse model of orthotopic xenograft prostate cancer and of IR-induced acute gastrointestinal syndrome. The effect of DPS on CEC DNA damage and DNA damage responses was determined by immunohistochemistry. Results: In the mouse model of IR-induced gastrointestinal syndrome, DPS treatment before IR accelerated recovery from body weight loss and increased animal survival. DPS decreased post-IR DNA damage and cell death, suggesting that the radioprotective effect was mediated by enhanced DNA damage repair. Shortly after DPS injection, significant cell cycle arrest was observed in CECs at both G1/S and G2/M checkpoints, which was accompanied by the activation of cell cycle inhibitors p21 and growth arrest and DNA-damage-inducible protein 45 alpha (GADD45A). Further investigation revealed that DPS activated ataxia telangiectasia mutated (ATM), an important inducer of DNA damage repair and cell cycle arrest. Conclusions: DPS selectively radioprotected normal intestinal CECs and sensitized prostate cancer cells in a clinically relevant model. This effect may be, at least in part, mediated by DNA damage response activation and has the potential to significantly increase the therapeutic index of radiation therapy

  17. Effects of taurolidine on radiosensitivity of murine melanoma cells and its mechanism

    International Nuclear Information System (INIS)

    Objective: To observe the effects of taurolidine on radiosensitivity of B16-F10 cells of murine melanoma via the enhancement of Bax and Bad proteins and induction of Bcl-2 protein. Methods: The apoptosis of B16-F10 cells was assessed after treated with 0, 10, 25, 50, 100 and 150 μmol·L-1 taurolidine, clone survival assay was used to detect the radiosensitivity of B16-F10 cells, and protein expressions were determined by Western blotting. Results: The apoptosis of 5% cells was induced in a dose-and time-dependent manner after B16-F10 cells were treated with 50 μmol·L-1 taurolidine. The survival rate decreased after treated with tautolidine in combination with 2 Gy X-irradiation with the increase of taurolidine concentration and doses of irradiation (P0 and SER Dq) also increased with the increase of its concentration, there was significant difference between 50 μmol·L-1 taurolidine group and 10 μmol·L-1 taurolidine group (P<0.05); meantime, the level of proapototic protein Bax and Bad increased and the level of antiapoptotic protein Bcl-2 reduced. Conclusion: Taurolidine in combination with irradiation can enhance the radiosensitivity by the mediation of Bcl-2 family protein. (authors)

  18. Metabolic potentiation of the radiosensitization of hypoxic bacterial cells afforded by nitroaromatic compounds

    International Nuclear Information System (INIS)

    Prolonged preirradiation incubation of nitroaromatic radiosensitizers with Escherichia coli cells has been found to increase the degree of radiosensitization of the cells in anoxia. Studies with E. coli strains which differ in their nitroreductase activity indicate that the increase in sensitization arises from the action of metabolites produced by the nitroreductase system of the cell. The metabolites alone appear to decrease the extrapolation number of irradiated hypoxic cells and when combined with the parent compound give a biphasic survival curve. The combination of misonidazole (1 mmole dm-3) and its metabolites (1 mmole dm-3) gave initial and final enhancement ratios of 2.4 and 1.4, respectively. The final enhancement ratio is that expected for 1 mmole dm-3 misonidazole alone, whereas the initial enhancement ratio indicates that the metabolites potentiate the action of misonidaxole. The preirradiation incubation effect is removed by dithiothreitol at concentrations which do not affect the radiosensitization level of the nitroaromatic sensitizer. This result indicates that the active metabolite probably depletes a certain amount of the free-thiol compounds inside the cell which assist in the repair of radiation-induced damage

  19. Radiosensitivity of brain cancer stem cells from malignant glicoma cell line U251 in vitro

    International Nuclear Information System (INIS)

    Objective: To investigate the radiosensitivity of brain cancer stem cells of different conditions isolated from malignant glioma cell line U251 irt vitro. Methods: The brain cancer stem cells in U251 or the brain cancer stem cells isolated from U251 were irradiated by 60Co γ-rays. TUNEL and Annexin-FITC were employed to detect the apoptosis. The brain cancer stem cells were subcutaneously transplanted to nude mouse. Flow cytometry was used to detect cell cycle. Results: The brain cancer stem cells isolated from malignant glioma cell line U251 were in active cell cycle and sensitive to 60Co γ-rays. Thed apoptotic cells were increased obviously after irradiation. After subcutaneously transplanted to unde mouse, there was no tumor appear. However; the brain cancer stem cells existed in U251 were in G0-G1 and resisted to 60Co γ-rays. They differentiated into the parent glioma type after traqnsplantation. Conclusions: The brain cancer stem cells existed in the malignant glioma cell line is resisted to irradiation, and this phenomenon may explain the glioma relapse irt situ after radiation therapy. (authors)

  20. Optimal energy for cell radiosensitivity enhancement by gold nanoparticles using synchrotron-based monoenergetic photon beams

    Directory of Open Access Journals (Sweden)

    Rahman WN

    2014-05-01

    Full Text Available Wan Nordiana Rahman,1,2 Stéphanie Corde,3,4 Naoto Yagi,5 Siti Aishah Abdul Aziz,1 Nathan Annabell,2 Moshi Geso21School of Health Sciences, Universiti Sains Malaysia, Kelantan, Malaysia; 2Division of Medical Radiation, School of Medical Sciences, Royal Melbourne Institute of Technology, Bundoora, VIC, 3Radiation Oncology, Prince of Wales Hospital, High Street, Randwick, 4Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia; 5Japanese Synchrotron Radiation Research Institute, Sayo-gun, Hyogo, JapanAbstract: Gold nanoparticles have been shown to enhance radiation doses delivered to biological targets due to the high absorption coefficient of gold atoms, stemming from their high atomic number (Z and physical density. These properties significantly increase the likelihood of photoelectric effects and Compton scattering interactions. Gold nanoparticles are a novel radiosensitizing agent that can potentially be used to increase the effectiveness of current radiation therapy techniques and improve the diagnosis and treatment of cancer. However, the optimum radiosensitization effect of gold nanoparticles is strongly dependent on photon energy, which theoretically is predicted to occur in the kilovoltage range of energy. In this research, synchrotron-generated monoenergetic X-rays in the 30–100 keV range were used to investigate the energy dependence of radiosensitization by gold nanoparticles and also to determine the photon energy that produces optimum effects. This investigation was conducted using cells in culture to measure dose enhancement. Bovine aortic endothelial cells with and without gold nanoparticles were irradiated with X-rays at energies of 30, 40, 50, 60, 70, 81, and 100 keV. Trypan blue exclusion assays were performed after irradiation to determine cell viability. Cell radiosensitivity enhancement was indicated by the dose enhancement factor which was found to be maximum at 40 keV with a value of 3

  1. Radiosensitivity enhancement of typical 15 nm polyethylene-glycol-coated Au nanoparticles on HepG2 cell

    International Nuclear Information System (INIS)

    Objective: To investigate the radiosensitivity enhancement of Au nanoparticles to HepG2 cell. Methods: 15 nm polyethylene-glycol-coated(PEG) Au nanoparticles were synthesized, and then blood stability were tested by using the UV-vis optical absorption. Meanwhile, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide methods were used to investigate the cell viability after 24 and 48 hours treatments, and cloning formation were used to investigate the radiosensitivity enhancement. Results: It was found that PEG-coated Au nanoparticles presented a high blood stability, and surface plasmon response has not shown significant changes after 24 hours. Cell viability was decreased after 24 hours treatment, but it was recovered to 90% after 48 hours. Cloning formation showed Au nanoparticles presented a significant radiosensitivity enhancement. Conclusion: 15 nm PEG-coated Au nanoparticles presented a good blood stability, low cytotoxicity and high radiosensitivity enhancement. (authors)

  2. The interaction of epidermal growth factor and radiation in human head and neck squamous cell carcinoma cell lines with vastly different radiosensitivities

    International Nuclear Information System (INIS)

    This study was performed to characterize the interaction of epidermal growth factor and radiation in two human head and neck squamous cell cancer cell lines of vastly different radiosensitivities (UM-SCC-6 radiosensitive; UM-SCC-1 radioresistant). It was determined that exposure to epidermal growth factor (10 ng/ml) for 24 h prior to radiation resulted in radiosensitization in both cell lines, however, the magnitude of radiosensitization was greater in the radiosensitive UM-SCC-6 cells compared to the radioresistant UM-SCC-1 cells. Treatment of the UM-SCC-6 cells with epidermal growth factor (EGF) (10 ng/ml) for 24 h resulted in a growth delay, however, cell growth returned to normal approximately 26 h following removal of EGF. Similar treatment of the UM-SCC-1 cells resulted in no growth inhibition. The 24 h preradiation exposures to EGF (10 ng/ml) did not affect the radiation-induced growth delay in either cell line. Additionally, the 24 h exposures to EGF (10 ng/ml) did not cause the cells to enter a more radiosensitive cell cycle phase. Further work will be necessary to determine whether events associated with the EGF-induced growth delay in the UM-SCC-6 cells are associated with the enhanced EGF-induced radiosensitization in these cells compared to UM-SCC-1 cells. 11 refs., 2 figs., 2 tabs

  3. Radiosensitization by misonidazole, pimonidazole and azomycin and intracellular uptake in human tumour cell lines

    International Nuclear Information System (INIS)

    Radiosensitization of two human tumour cell lines, HT-1080 and LoVo was compared with Chinese hamster line V73-379A. Although the two human lines were more radiosensitive than V79, enhancement ratios for misonidazole, pimonidazole and azomycin were similar for all three. In all cells uptake of misonidazole and azomycin was very rapid; that of pimonidazole was initially much slower before reaching a plateau. The ratios of intracellular concentration of radiosensitizer to extracellular concentration (Ci to Ce)for misonidazole were 0.8 (HT-1080) and 0.7 (LoVo and V79); for azomycin 0.9 (HT-1080 and LoVo) and 0.8 (V79). CiCe for pimonidazole varied with cell line [1.8 (LoVo), 2.6 (HT-1080) and 3.3 (V79)]. When average cell volume was taken into consideration, concentrations of non-protein sulphydryl were very similar [4.2 (HT-1080), 5.6 (LoVo), 5.7 (V79) m mol dm-3]. MPSH levels expressed as n mol/mg protein were also similar. (author)

  4. Thioredoxin reductase-1 (TxnRd1) mediates curcumin-induced radiosensitization of squamous carcinoma cells

    OpenAIRE

    Javvadi, Prashanthi; Hertan, Lauren; Kosoff, Rachelle; Datta, Tatini; Kolev, Johann; Mick, Rosemarie; Tuttle, Stephen W; Koumenis, Constantinos

    2010-01-01

    Curcumin, a plant polyphenol, is a widely studied chemopreventive agent with demonstrated antitumor activities in preclinical studies and low toxicity profiles in multiple clinical trials against human malignancies. We previously demonstrated that curcumin radiosensitizes cervical tumor cells without increasing the cytotoxic effects of radiation on normal human fibroblasts. Here we report that an inhibitory activity of curcumin on the anti-oxidant enzyme Thioredoxin Reductase-1 (TxnRd1) is re...

  5. Ocular absorption and toxicity of a radiosensitizer and its effect on hypoxic cells

    International Nuclear Information System (INIS)

    The recurrence of retinoblastoma after radiation treatment may be related to hypoxic cell radioresistance. Radiosensitizing drugs acting on hypoxic cells without affecting the response of oxygenated cells could improve treatment of ocular tumors while minimizing complications of radiotherapy. A desmethyl derivative of misonidazole is as effective a radiosensitizer as misonidazole (as measured in vitro) and is better suited to ocular administration, since it is more soluble than misonidazole. We studied the ocular toxic effects of a desmethyl derivative of misonidazole after subconjunctival administration of 140 and 70 mg. The higher dose produced an intolerable ocular toxic effect, but at the lower dose, the toxic effect was moderate and reversible. We compared ocular pharmacokinetics of the desmethyl derivative of misonidazole after subconjunctival and intravenous (IV) injections. Subconjunctival administration yielded vitreous and anterior chamber concentrations of the radiosensitizer sufficient to produce a notable dose-modifying effect (as high as 1.8 in the anterior chamber and 1.25 in the vitreous at 70-mg doses). In contrast, even at doses of 140 mg, IV injections of the desmethyl derivative of misonidazole did not result in therapeutically useful ocular levels

  6. Radiosensitizing effect of medroxyprogesterone acetate on endometrial cancer cells in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Huber, H.; Husslein, P.; Michalica, W.; Wagenbichler, P.

    1984-09-15

    From clinical experience it is known that medroxyprogesterone acetate (MPA) can increase the radiosensitivity of adenocarcinomas of the corpus uteri. This study investigates this phenomenon in vitro. Primary explants of highly differentiated adenocarcinomas were irradiated with or without pretreatment with MPA and compared with an untreated control group and to a group treated with MPA only. Cell culture itself was performed on an agarose medium in order to prevent overgrowth by fibroblasts. Untreated samples formed 43 +/- 5 clones, explants treated with MPA only produced 39 +/- 5 clones, a difference which was not statistically different; samples irradiated without pretreatment produced 16 +/- 8 and samples after combined treatment 9 +/- 3 clones (all values means +/- SD). This numeric reduction of cell growth through preirradiation treatment with MPA was statistically significant. The effect of MPA as a radiosensitizer may be due to its potential to prolong the radiosensitive G2 phase of the cell cycle. This effect of MPA may be useful also in other hormone-dependent tumors.

  7. Hypoxia-selective radiosensitization of mammalian cells by nitracrine, an electron-affinic DNA intercalator

    International Nuclear Information System (INIS)

    NC (1-nitroacridine nitracine) radiosensitization was evaluated in CHO cultures at 40C. Under hypoxia, submicromolar concentrations resulted in sensitization (SER=1.6 at μ mol dm-3). In aerobic conditions, a concentration more than 10-fold higher was required. In aerobic cultures, NC radiosensitization was independent of time of exposure. Postirradiation sensitization was not observed under hypoxia. Time dependence of NC uptake and development of radiosensitization were similar, suggesting that sensitization is due to unmetabolized drug. NC was about 1700 times more potent than misonidazole, (accounted for by the electron affinity of NC (E(1) value at pH 7 of -275 mV versus NHE)) and by its accumulation in cells to give intracellular concentrations approximately 30 times greater than in the medium. Concentrations of free NC appear to be low in AA8 cells, presumably due to DNA binding. If radioisensitization by NC is due to bound rather than free drug, it is suggested that intercalated NC can interact efficiently with DNA target radicals, despite a binding ratio in the cell, estimated as less than 1 NC molecule/400 base pairs under conditions providing efficient sensitization. (U.K.)

  8. Glycosphingolipids in L5178Y murine lymphoma cell sublines differing in radiosensitivity

    International Nuclear Information System (INIS)

    Glycolipid content and composition of LY-S and LY-R sublines of murine lymphoma L5178Y cell line differing in radiosensitivity (LY-S being more sensitive to ionizing radiation) were analysed. Both sublines differ in their lipid-bound sialic acid (in LY-S cells 1.5 times more than in LY-R) and ganglioside content (more in LY-S cells). A small difference between these two sublines was also found in composition of neutral glycosphingolipids. The results were compared with those described for other L5178Y cell variants. 18 refs., 3 figs., 3 tabs. (author)

  9. Effect of elemene on radiosensitivity of A549 cells and its possible molecular mechanism

    International Nuclear Information System (INIS)

    Objective: To investigate the effect of elemene on the radiosensitivity of A549 cells and its possible molecular mechanism. Methods: The effect of radiosensitivity was detected by colony forming assay. The protein expressions of DNA-PKcs, Bcl-2 and P53 were detected with Western blot. The correlation between the protein expression of DNA-PKcs and Bcl-2, DNA-PKcs and P53 was analyzed. Results: Elemene had radiosensitizing effect on A549 cells, with the SERD0 and SERDq 1.54 ± 0.20 and 1.43±0.15, respectively for 10 μg/ml elemene, and 1.63 ±0.32 and 1.75 ±0.19, respectively for 20 μg/ml elemene. Compared with irradiation group, the expression of DNA-PKcs was reduced significantly in 10, 20 μg/ml elemene combined with radiation group (t=7.52, 8.33, P<0.05), so was for Bcl-2 (t=10.74, 11.33, P<0.05). The expression of P53 protein increased significantly (t=-9.25, 7.66, P<0.05). There was a remarkable negative correlation between the expression of DNA-PKcs and P53 (r=-0.569, P<0.05), and a remarkable positive correlation between DNA-PKcs and Bcl-2 (r=0.755, P<0.05 ). Conclusions: Elemene has radiosensitizing effect on A549 cells, which might be related to down-regulation of DNA-PKcs gene expression, up-regulation of P53 and down-regulation of Bcl-2. (authors)

  10. Artemisinin derivative artesunate induces radiosensitivity in cervical cancer cells in vitro and in vivo

    International Nuclear Information System (INIS)

    Cervical cancer is the third most common type of cancer in women worldwide and radiotherapy remains its predominant therapeutic treatment. Artesunate (ART), a derivative of artemisinin, has shown radiosensitization effect in previous studies. However, such effects of ART have not yet been revealed for cervical cancer cells. The effect of ART on radiosensitivity of human cervical cancer cell lines HeLa and SiHa was assessed using the clonogenic assay. Cell cycle progression and apoptosis alterations were analyzed by flow cytometry. For in vivo study, HeLa or SiHa cells were inoculated into nude mice to establish tumors. Tissues from xenografts were obtained to detect the changes of microvessel density, apoptosis and cell cycle distribution. Microarray was used to analyze differentially expressed genes. ART increased the radiosensitivity of HeLa cells (SER = 1.43, P < 0.001) but not of SiHa cells. Apoptosis and the G2-M phase transition induced by X-ray irradiation (IR) were enhanced by ART via increased Cyclin B1 expression in HeLa cells. Tumor growth of xenografts from HeLa but not SiHa cells was significantly inhibited by irradiation combined with ART (tumor volume reduction of 72.34% in IR + ART group vs. 41.22% in IR group in HeLa cells and 48.79% in IR + ART group vs. 44.03% in IR alone group in SiHa cells). Compared with the irradiated group, cell apoptosis was increased and the G2/M cell cycle arrest was enhanced in the group receiving irradiation combined with ART. Furthermore, compared with radiation alone, X-ray irradiation plus ART affected the expression of 203 genes that function in multiple pathways including RNA transport, the spliceosome, RNA degradation and p53 signaling. ART potently abrogates the G2 checkpoint control in HeLa cells. ART can induce radiosensitivity of HeLa cells in vitro and in vivo

  11. Quantitative and comparative proteomics analysis of radiosensitivity for colorectal cancer cells

    International Nuclear Information System (INIS)

    To identify the related proteins about radiosensitivity (RS) of colorectal cancers,as well as make the personal therapeutics for patients, the specimen of transplanted tumor raised by the colorectal cancer cells, LOVO and SW480 with different radiosensitivity, were examined by the fluorescence differential in-gel electrophoresis (DIGE) after labeled with CyDye DIGE fluors Cy3, Cy5 and Cy2. As the result, intensity changes of 35 spots were detected with statistical significance. 18 protein spots of them are up-regulated in tumor specimen of LOVO, otherwise 17 are up-regulated in specimen of SW480. And 27 of them were identified by MALDI-TOF-MS successfully including 17 in LOVO and 15 in SW480. These differential expressed proteins may become the mocular markers and have a key role in predicting the RS of colorectal cancer. (authors)

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

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Yan Nan; Shin, Hyun-Jin; Joo, Hyun-Yoo; Park, Eun-Ran; Kim, Su-Hyeon; Hwang, Sang-Gu [Division of Radiation Cancer Research, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of); Park, Sang Jun; Kim, Chun-Ho [Laboratory of Tissue Engineering, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of); Lee, Kee-Ho, E-mail: khlee@kirams.re.kr [Division of Radiation Cancer Research, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of)

    2014-01-17

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

  13. Radiosensitization and hypoxic cell toxicity of NLA-1 and NLA-2, two new bioreductive compounds

    Energy Technology Data Exchange (ETDEWEB)

    Papadopoulou, M.V.; Epperly, M.W.; Shields, D.S. (Pittsburgh Cancer Institute PA (USA)); Bloomer, W.D.

    1992-04-01

    Two new bioreductive compounds, 9-(3-(2-nitro-1-imidazolyl)propylamino)acridine hydrochloride (NLA-1) and 9-(2-(2-nitro-1-imidazolyl)ethylamino)acridine hydrochloride (NLA-2), have been prepared. They feature an acridine ring to intercalate with DNA, a 2-nitroimidazole ring as the radiosensitizing moiety and an amino functionality for increased DNA-binding and hydrophilicity. Time concentration dependent cytotoxicity as well as radiosensitization efficacy of the two compounds under hypoxic or aerobic conditions were determined in vitro using V-79 cells and an MTT colorimetric or clonogenic assay. The isosensitization point (ISP), defined as that drug concentration which results in the same survival decrement upon exposure of hypoxic of oxygenated cells to a given radiation dose, has been determined for both compounds at 7.5 Gy and the values are significantly lower than the ISPs of 5-(3-(2-nitro-1-imidazolyl)propyl)phenanthridinium bromide, 2-(2-nitro-1-imidazolyl)ethylamine or misonidazole (MISO). NLA-1 and NLA-2 are potent hypoxic cytotoxins and on a concentration basis, more potent than MISO as radiosensitizers in vitro. The sensitization enhancement ratios were significantly increased when 1 h drug preincubation under hypoxia at 37degC was applied, before irradiation at room temperature. (author).

  14. Differences in DNA Repair Capacity, Cell Death and Transcriptional Response after Irradiation between a Radiosensitive and a Radioresistant Cell Line.

    Science.gov (United States)

    Borràs-Fresneda, Mireia; Barquinero, Joan-Francesc; Gomolka, Maria; Hornhardt, Sabine; Rössler, Ute; Armengol, Gemma; Barrios, Leonardo

    2016-01-01

    Normal tissue toxicity after radiotherapy shows variability between patients, indicating inter-individual differences in radiosensitivity. Genetic variation probably contributes to these differences. The aim of the present study was to determine if two cell lines, one radiosensitive (RS) and another radioresistant (RR), showed differences in DNA repair capacity, cell viability, cell cycle progression and, in turn, if this response could be characterised by a differential gene expression profile at different post-irradiation times. After irradiation, the RS cell line showed a slower rate of γ-H2AX foci disappearance, a higher frequency of incomplete chromosomal aberrations, a reduced cell viability and a longer disturbance of the cell cycle when compared to the RR cell line. Moreover, a greater and prolonged transcriptional response after irradiation was induced in the RS cell line. Functional analysis showed that 24 h after irradiation genes involved in "DNA damage response", "direct p53 effectors" and apoptosis were still differentially up-regulated in the RS cell line but not in the RR cell line. The two cell lines showed different response to IR and can be distinguished with cell-based assays and differential gene expression analysis. The results emphasise the importance to identify biomarkers of radiosensitivity for tailoring individualized radiotherapy protocols. PMID:27245205

  15. Radiosensitivity and effect of hypoxia in HPV positive head and neck cancer cells

    International Nuclear Information System (INIS)

    Background and purpose: HPV associated Head and Neck Squamous Cell Carcinoma (HNSCC) represents a distinct subgroup of HNSCC characterized by a favorable prognosis and a distinct molecular biology. Previous data from the randomized DAHANCA 5 trial indicated that HPV positive tumors did not benefit from hypoxic modifications by Nimorazole during radiotherapy, whereas a significant benefit was observed in the HPV negative tumors. However, more studies have demonstrated equal frequencies of hypoxic tumors among HPV-positive and HPV-negative tumors. The aim of the present study was to determine radiosensitivity, the impact of hypoxia and the effect of Nimorazole in HPV positive and HPV negative cell lines. Materials and method: The used cell lines were: UDSCC2, UMSCC47 and UPCISCC90 (HPV positive) and FaDuDD, UTSCC33 and UTSCC5 (HPV negative). Cells were cultured under normoxic or hypoxic conditions, and gene expression levels of previously established hypoxia induced genes were assessed by qPCR. Cells were irradiated with various doses under normoxia, hypoxia or hypoxia +1 mM Nimorazole, and the clonogenic survival was determined. Results: The HPV positive and HPV negative cell lines exhibited similar patterns of upregulation of hypoxia induced genes in response to hypoxia. The HPV positive cell lines were up to 2.4 times more radiation sensitive than HPV negative cell lines. However, all HPV positive cells displayed the same response to hypoxia in radiosensitivity, with an OER in the range 2.3–2.9, and a sensitizer effect of Nimorazole of 1.13–1.29, similar to HPV negative cells. Conclusions: Although HPV positive cells had a markedly higher radiosensitivity compared to HPV negative cells, they displayed the same relative radioresistance under hypoxia and the same relative sensitizer effect of Nimorazole. The clinical observation that HPV positive patients do not seem to benefit from Nimorazole treatment is not due to inherent differences in hypoxia sensitivity

  16. Omega-3 fatty acid supplementation in cancer therapy. Does eicosapentanoic acid influence the radiosensitivity of tumor cells?

    Energy Technology Data Exchange (ETDEWEB)

    Manda, Katrin; Kriesen, Stephan; Hildebrandt, Guido [Rostock Univ. (Germany). Dept. of Radiotherapy; Fietkau, Rainer; Klautke, Gunther [Univ. Hospital Erlangen, Erlangen (Germany). Dept. of Radiation Oncology

    2011-02-15

    Purpose: The aim of this study was to evaluate whether the omega-3 polyunsaturated fatty acid cis-5,8,11,14,17-eicosapentanoic acid (EPA) can enhance the radiosensitivity of different human tumor cell lines. Materials and Methods: Colon adenocarcinoma cells HT-29, and two glioblastoma multiforme tumor cells T98G and U251 were cultured under standard conditions. Cell growth was observed during administration with different concentrations of EPA, using it as the free fatty acid dissolved in ethanol or bound to bovine serum albumin. To investigate the influence of EPA (free and bound) on radiosensitivity, tumor cells were pretreated 30 minutes or 24 hours prior to irradiation with the fatty acid. Cell survival was measured by colony-forming assays. Results: When combined with irradiation, incubation with EPA was found to result in enhanced radiosensitivity with substantial variation: while there was strong radiosensitization for HT-29 and U251 cells, almost no effect for T98G cells was observed. A marked radiosensitization was clearly dependent on the treatment schedule. Conclusion: The observations suggest that EPA is not only a nutritional adjuvant but also may be a potential candidate to enhance the efficacy of irradiation on human cancer cells. (orig.)

  17. EGFR-dependent Impact of Indol-3-Carbinol on Radiosensitivity 
of Lung Cancer Cells

    OpenAIRE

    Xiao, Xiao(Institute for Strings, Cosmology and Astroparticle Physics (ISCAP) and Physics Department, Columbia University, 538 West 120th Street, New York, NY, 10027 U.S.A.); Meng, Qinghui; Xu, Jiaying; Jiao, Yang; Rosen, Eliot M.; Fan, Saijun

    2012-01-01

    Background and objective Indole-3-carbinol (I3C) is a naturally occurring phytochemical found in cruciferous vegetables. The aim of the present study is to investigate the influence of I3C on radiosensitivity in epidermal growth factor receptor (EGFR)-positive and EGFR-negative lung cancer cell lines. Methods Human lung adenocarcinoma NIH-H1975 cells and human lung squamous carcinoma NIH-H226 and NIH-H520 cells were routinely cultured in RPMI-1640. MTT assay and clonogenic assay were used to ...

  18. The c-Met receptor tyrosine kinase inhibitor MP470 radiosensitizes glioblastoma cells

    International Nuclear Information System (INIS)

    Glioblastoma multiforme (GBM) is resistant to current cytotoxic therapies, in part because of enhanced DNA repair. Activation of the receptor tyrosine kinase c-Met has been shown to protect cancer cells from DNA damage. We hypothesized that inhibiting c-Met would decrease this protection and thus sensitize resistant tumor cells to the effects of radiation therapy. Eight human GBM cell lines were screened for radiosensitivity to the small-molecule c-Met inhibitor MP470 with colony-count assays. Double-strand (ds) DNA breaks was quantified by using antibodies to gamma H2AX. Western blotting demonstrate expression of RAD51, glycogen synthase kinase (GSK)-3β, and other proteins. A murine xenograft tumor flank model was used for in vivo radiosensitization studies. MP470 reduced c-Met phosphorylation and enhanced radiation-induced cell kill by 0.4 logs in SF767 cells. Cells pretreated with MP470 had more ds DNA damage than cells treated with radiation alone. Mechanistically, MP470 was shown to inhibit dsDNA break repair and increase apoptosis. MP470 influences various survival and DNA repair related proteins such as pAKT, RAD51 and GSK3β. In vivo, the addition of MP470 to radiation resulted in a tumor-growth-delay enhancement ratio of 2.9 over radiation alone and extended survival time. GBM is a disease site where radiation is often used to address both macroscopic and microscopic disease. Despite attempts at dose escalation outcomes remain poor. MP470, a potent small-molecule tyrosine kinase inhibitor of c-Met, radiosensitized several GBM cell lines both in vitro and in vivo, and may help to improve outcomes for patients with GBM

  19. Role of novel anticancer drug Roscovitine on enhancing radiosensitivity in carcinoma cell lines

    International Nuclear Information System (INIS)

    The present study was conducted to evaluate the radiosensitization effect of Roscovitine (cyclin dependent kinase inhibitor) in carcinoma cell lines. Three cell lines are used liver carcinoma cell line (HepG2), brain carcinoma cell line (U251), Lung carcinoma cell line (H460) in this study cells were treated with Roscovitine in different concentrations ranging from 0.1 ?M to 100 ?M before exposure to radiation doses ranging from 0.5 Gy to 20 Gy according to each experiment. The cell viability by MTT assay, the cell cycle analysis by flow cytometry and DNA fragmentation repair mechanism by diphenylamine were measured after Roscovitine treatment with or without radiation exposure to explore the sensitization effect of Roscovitine. The present study conclude that Roscovitine a good candidate as radiosensitizer for modifying the ionizing radiation (IR) response in cancer cells, beside its cyclin dependent kinase inhibitor function, Roscovitine can generate DNA Double strand Breaks and cooperate to enhance IR induce DNA damages. Roscovitine is currently in clinical trials, although our findings suggest that the combination of Roscovitine with IR appears to be a very promising especially for liver, brain and lung cancer treatment, further investigation is needed to evaluate the therapeutic index before tested in clinical trials

  20. Role of novel anticancer drug Roscovitine on enhancing radiosensitivity in carcinoma cell lines

    International Nuclear Information System (INIS)

    The present study was conducted to evaluate the radiosensitization effect of Roscovitine (cyclin dependent kinase inhibitor) in carcinoma cell lines. Three cell lines are used (HepG2 liver carcinoma cell line, U251 brain carcinoma cell line, H460 Lung carcinoma cell line) in this study .cells were treated with Roscovitine in different concentrations ranging from 0.1μM to 100 μM before exposure to radiation doses ranging from 0.5 Gy to 20 Gy according to each experiment. The cell viability by MTT assay, The cell cycle analysis by flow cytometry and DNA fragmentation repair mechanism by diphenylamine were measured after Roscovitine treatment with or without radiation to explore the sensitization effect of Roscovitine. The present study conclude that Roscovitine a good candidate as radiosensitizer for modifying the ionizing radiation (IR) response in cancer cells, beside its cyclin dependent kinase inhibitor function, roscovitine can generate DNA Double strand Breaks and cooperate to enhance IR induce DNA damages . Roscovitine is currently in clinical trials, although our findings suggest that the combination of Roscovitine with IR appears to be a very promising especially for liver, brain and lung cancer treatment, further investigation is needed to evaluate the therapeutic index before tested in clinical trial

  1. Effect of BRCA1 on radiosensitivity of different lung cancer cells

    International Nuclear Information System (INIS)

    Objective: To investigate the effects BRCA1 on sensitivity of lung cancer cells to γ-irradiation. Methods: A mammalian expression pcDNA3 vectors encoding a full-length of BRCA1 cDNA and BRCA1 siRNA were transfected into lung cancer cells. Western blot, MTT and clonogenic assays were used to determine BRCA1 protein expression and cell survival following γ-irradiation respectively. Results: There is a close relationship between BRCA1 level and radiosensitivity in different lung cancer cell lines. Compared with the control cells transfected with the 'empty' pcDNA3 vector and parental cells, the more survival of cells transfected with BRCA1 was observed after irradiation. The BRCA1-caused radioresistance were observed in both A549 and HTB-58 lung cancer lines. However, NIH-H2170 cells transfected with BRCA1 siRNA became more sensitive to γ-irradiation. Conclusion: This study, for the first time, demonstrates that the alteration of BRCA1 expression significantly affects radiosensitivity of lung cancer, indicating that BRCA1 may be an important mediator in radiotherapy of lung cancer cells. (authors)

  2. Partial knockdown of TRF2 increase radiosensitivity of human mesenchymal stem cells.

    Science.gov (United States)

    Orun, O; Tiber, P Mega; Serakinci, N

    2016-09-01

    Telomere repeat binding factor TRF2 is a member of shelterin complex with an important role in protecting and stabilizing chromosomal ends. In the present study, we investigated the effect of partial knockdown of TRF2 on radiosensitivity of telomerase immortalized human mesenchymal stem cells (hMSC-telo1), which have a higher radioresistance compared to non telomerized counterpart. Partial knockdown of the protein achieved 15-20% reduction in TRF2 protein levels. The study compared the effect of 2.5Gy radiation in two-four days after irradiation for hMSC-telo1 cells and the cells transfected with siTRF2 and null control vector. Radio-response of the cells were examined using senescence associated β-Gal assay (β-Gal), colony forming assay (CFU) and γ-H2AX phosphorylation. TRF2 deficiency substantially increased radiosensitivity of cells compared to controls in both proliferation and senescence assay (2.4 fold increase in β-Gal, 1.6 fold decrease in CFU). In addition, it increased the γ-H2AX foci as revealed by both immunfluorescence and Western blot analysis. Our data suggests that partial knockdown of TRF2 in hMSC-telo1 cells cause increased γ-H2AX foci which led to fail TRF2 to protect telomeres from radiation thus TRF2 deficiency led to a 1,5-2 fold increase in the radiosensitivity of hMSC-telo1 cells through telomere destabilization. PMID:26598048

  3. Adenovirus E4orf6 protein inhibits DNA repair and radiosensitizes human tumor cells

    International Nuclear Information System (INIS)

    Full text: Double strand break repair (DSBR), although vital to normal cell survival and genomic stability, limits tumor cell kill following treatment with ionizing radiation (IR). The primary mechanism for DSBR in mammalian cells, non-homologous end joining (NHEJ), requires multiple proteins, one of which is DNA-dependent protein kinase (DNA-PK). Cells deficient in DNA-PK, although phenotypically normal, are among the most radiosensitive cells available. It has previously been shown that the E4orf6 gene product of adenovirus type 5 interacts with and inhibits the activity of DNA-PK. Therefore, we hypothesized that E4orf6, by interacting with DNA-PK, would inhibit the DSBR capacity of tumor cells and thus increase tumor cell kill upon treatment with IR. Stable clones expressing either wild type E4orf6, an E4orf6 mutant (L245P) that is defective at E1B-55K localization to the nucleus, or a neomycin control vector were established in colorectal carcinoma (RKO) cells. Based on clonogenic assays, we report a 10-fold increase in radiosensitivity of the wild type E4orf6 expressing clones at 6Gy of IR compared to both the neomycin and L245P mutant clones. Furthermore, the increase in sensitivity correlates with inhibition in DSBR based on sub-lethal damage repair assay. Preliminary data suggests that the transfected E4orf6 interacts with the endogenous DNA-PK and this results in a 20% decrease in the kinase activity of the DNA-PK compared to neomycin expressing control cells. These results indicate that E4orf6 radiosensitizes tumor cells by inhibiting their DSBR activity. We have constructed an adenoviral vector expressing E4orf6 in a tetracycline-inducible manner, which provides temporal control for E4orf6 expression. We are currently investigating the radiosensitizing properties of this expression vector. Successful use of this vector in vitro and in mouse xenografts, will set the stage for its future use in conjunction with localized radiotherapy of radioresistant

  4. Small interfering RNA in silencing Bcl-2 expression and enhancing radiosensitivity of esophageal cancer cells

    International Nuclear Information System (INIS)

    Objective: To explore the effects of small interfering RNA (siRNA) specific to Bcl-2 gene on radiosensitivity of esophageal cancer cells. Methods: Bcl-2 gene siRNA ( Bcl-2 siRNA ) was induced into esophageal cancer EC9706 cells by lipofectamine. Bcl-2 protein expression and apoptosis of EC9706 cells were detected by flowcytometer. Clone forming assay was used to determine the inhibitory effects of X-ray radiation combined with Bcl-2 siRNA interference. Results: When Bcl-2 siRNA had been induced into EC9706 cells, Bcl-2 protein expression in EC9706 cells was inhibited, and cell apoptosis was increased. Bcl-2 protein expression rates of EC9706 cells induced with Bcl-2 siRNA1, A2, A3 (25.13% ±2.04%, 8.87% ± 3.34%, 30.55% ± 2.73%) were lower than the control group (84.28% ± 1.47%)(t =4.01, 3.043.64, P 0, Dq, and SF2 of combined treatment group were much lower than those of irradiation alone group . The sensitization enhancing ratio was 1.32 (ratio of D0 values). Conclusions: Bcl-2 gene siRNA could enhance the radiosensitivity of esophageal cancer EC9706 cells and may has a good future in clinical practice. (authors)

  5. Radiosensitization of acetaminophen on human glioma cell lines and its mechanism

    International Nuclear Information System (INIS)

    Objective: To investigate the radiosensitivity enhancement and underlying mechanism of acetaminophen, non-selective cyclooxygenase (COX)-2 inhibitor, on human glioma cell lines expressing differential COX-2 levels. Methods: The SHG-44 cells were irradiated with a dose of 10 Gy using 6 MV X-rays generated by linear accelerator. The progeny of the cells were cultured and named SHG-4410Gy. COX-2 mRNA and protein expression of SHG-44 and SHG-4410Gy were detected by RT-PCR and immunocytochemisty staining. Clongenic assay was used for radiation survival experiment. Results: The declined radiosensitivity was detected in the SHG-4410Gy. RT-PCR showed that the expression of COX-2 mRNA in SHG-4410Gy significantly higher than that in SHG-44 cells (P0) or 1.11(Dq) in SHG-44 cells and 1.12(D0) or 3.01 (Dq) in SHG-4410Gy. Conclusions: SHG-4410Gy cells are more radio-resistant, and one of the fundamental mechanisms might be the upregulation of COX-2 expression in protein and mRNA levels. Acetaminophen could enhance the radisensitivity of glioma cells, especially the surviving progeny from the irradiated SHG-44 cells. (authors)

  6. Semaphorin3B modulates radiosensitivity of human glioma U-87MG cells

    International Nuclear Information System (INIS)

    This study was to determine the Semaphorin3B (SEMA3B) role in glioma cells responding to irradiation. Two glioma cell lines, which were used here was wild-type p53 (U-87MG), and the other was harboring mutated p53 (U-251). The SEMA3B mRNA could be detected in the two cell lines. The expression level of SEMA3B mRNA was higher in U-87MG cells than in U-251 cells, and increased with time in U-87MG cells after irradiation. Knockdown of SEMA3B expression by shRNA decreased the radiosensitivity of U-87MG cells, this may be associated with the increased G2 accumulation after irradiation. In addition, G2 accumulation after irradiation was enhanced in SEMA3B low-expressing U-87MG cells. These results showed that the SEMA3B was implicated in glioma cells responding to irradiation. (authors)

  7. The radiosensitization effect of Tat-SmacN7 on breast cancer cell lines

    International Nuclear Information System (INIS)

    Objective: To investigate the radiosensitive effect of Tat-SmacN7 on human breast cancer cell line of SK-BR-3 and the underlying mechanism. Methods: SK-BR-3 cells in the logarithmic phase were divided into 4 groups: control group,drug group, 137Cs γ-ray radiation group and the case group (γ-ray radiation + Tat-SmacN7). MTT assay was performed to evaluate the cytotoxicity of Tat-SmacN7. Colony formation assay was used to measure cell survival fraction. A single-hit multi-target model was used to fit the survival curve and calculate the sensitive enhancement ratio (SER). Apoptosis rate was analyzed by using flow cytometry. The expressions of inhibitor of apoptosis proteins (IAP) including XIAP, cIAP-1 proteins were detected by Western blot method. Results: Tat-SmacN7 inhibited cell growth in a dose-dependent manner (r =0.924, P<0.05) and its 50% inhibition concentration (IC50) was (62.62 ± 1.19) μmol/L, and IC20 was (5.66 ± 0.67) μmol/L. In addition, 5 μmol/L Tat-SmacN7 could enhance cell radiosensitivity with a SER of 1.48. After 6 Gy γ-ray radiation at 48 h, the incidence of apoptosis in the case group was higher than that in the irradiation alone group (t =7.01, P<0.05). Tat-SmacN7 only inhibited XIAP expression, whereas Tat-SmacN7 combined with radiation inhibited cIAP-1 as well. Conclusions: Tat-SmacN7 has a radiosensitization effect on human breast cancer SK-BR-3 cell by promoting apoptosis,which might be related with XIAP expression. (authors)

  8. The radiosensitivity of some trisomic variants of a diploid mammalian cell line

    International Nuclear Information System (INIS)

    The radiosensitivity of trisomic cells from a diploid BHK21 Cl3 cell line was investigated. The technique used confined measurement of most of the established criteria to a single set of direct observations on one population of cells, and the results from this method were compared with those obtained from some more conventional techniques. Trisomic cells were isolated after a chronic treatment of the diploid cells with low doses of colcemid, which increased the incidence of nondisjunction at anaphase. Over several cell cycles the incidence of trisomy in the population increased to the extent where standard cloning techniques yielded a tolerably high proportion of trisomic clones. The radiosensitivity of one of these clones was examined in detail and the results compared with those obtained by other workers. Other trisomic clones were also assayed for the incidence of chromosome aberrations, post irradiation colony-forming ability and tumourigenicity to identify any which display markedly individual characteristics. These results and their implications in the radiobiology of mammalian cells are discussed. (author)

  9. Radiosensitization of cetuximab on human tongue cancer cell line Tca8113

    International Nuclear Information System (INIS)

    Objective: To investigate the mechanism of radiosensitization by cetuximab (C225) on human tongue cancer Tca8113 cell line in vitro. Methods: Tca8113 cell line with and without C225 treatment received 6 MV X-ray irradiation of different doses (0, 2, 4, 6, 8 and 10 Gy). Cell proliferation, cell-cycle distribution and clonogenic survival were analyzed through cell counting, MTT, colony formation assay, and flow cytometry, respectively. Results: After irradiation of different doses, the growth inhibition rates in C225 group were higher than control (t =-15.6 - -3.0, P<0.05), the radiobiological parameters (D0, Dq, N, and SF2) in C225 group were lower than control so that SER of C225 group was 1.353, and the proportions of G0/G1 cells in C225 group were higher than control (t=-7.64, -7.89, -4.78, P<0.05) at 4, 6, 8 Gy. When the irradiation doses increased, the early phase apoptosis in both groups increased at first and then decreased with the maximum difference at 4 Gy [(7.96±0.36)% in C225 group and (4.13 ±0.29)% in control group, t=-12.75, P<0.01]. Conclusions: C225 has radiosensitization effect on Tca8113 cell line, possible through G0/G1 arrest and induction of apoptosis. (authors)

  10. The radiosensitivities of 4 human tumor cell lines to p (35) Be neutron irradiation

    International Nuclear Information System (INIS)

    Objective: The difference of radiosensitivity of 4 human tumor cell lines to p(35)Be fast neutron and gamma ray was studied in order to provide basis for clinical therapy of tumors. Methods: The radiosensitivity of these cell lines after p(35)Be neutron or gamma ray irradiation was assayed with cell clonogenic survival assay. And the gamma ray-and p(35)Be neutron-induced DNA damage and its repair in human melanoma cells line WM9839 was studied by using the method of comet-electrophoresis assay. Results: The difference of D0(or SF2) after p(35)Be neutron irradiation between these 4 human tumor cell lines was smaller than that after gamma ray irradiation. The repair rate of DNA damage in WM9839 cells after 2 Gy fast-neutron irradiation was lower than that after 2 Gy γ-ray irradiation. The residual DNA damage at 180 min after neutron-irradiation was obviously severer than that after 2 Gy γ-ray irradiation. Conclusion: The fast neutron therapy may make up the defect of the low LET ray therapy, especially to those radioresistant tumor cells to low LET rays

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

    International Nuclear Information System (INIS)

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

  12. MG132 enhances the radiosensitivity of lung cancer cells in vitro and in vivo.

    Science.gov (United States)

    Zhu, Wei; Liu, Jing; Nie, Jihua; Sheng, Wenjiong; Cao, Han; Shen, Wenhao; Dong, Aijing; Zhou, Jundong; Jiao, Yang; Zhang, Shuyu; Cao, Jianping

    2015-10-01

    Radiotherapy is a common treatment modality for lung cancer, however, radioresistance remains a fundamental barrier to attaining the maximal efficacy. Cancer cells take advantage of the ubiquitin-proteasome system (UPS) for increased proliferation and decreased apoptotic cell death. MG132 (carbobenzoxyl-leucinyl-leucinyl-leucinal‑H), a specific and selective reversible inhibitor of the 26S proteasome, has shown anticancer effect in multiple types of cancers. Previously, we have reported that MG132 enhances the anti‑growth and anti-metastatic effects of irradiation in lung cancer cells. However, whether MG132 can enhance the radiosensitivity in lung cancer cells in vitro and in vivo is still unknown. In this study, we found that MG132 increased apoptosis and dicentric chromosome ratio of A549 and H1299 cells treated by irradiation. Radiation-induced NF-κB expression and IκBα phosphorylation was attenuated in MG132 plus irradiation-treated cells. The in vivo model of H1299 xenografts of nude mice showed that the tumor size of MG132 plus irradiation treated xenografts was smaller than that of irradiation, MG132 or the control group. Moreover, MG132 plus irradiation group showed significant reduced Ki67 expression. Taken together, these results demonstrate that MG132 enhances the radiosensitivity through multiple mechanisms in vitro and in vivo. PMID:26238156

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-09-15

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

  14. Adenovirus-mediated p53 gene transfer increases radiosensitivity of human gastric carcinoma cells

    International Nuclear Information System (INIS)

    Objective: To evaluate the effect of adenovirus-mediated p53 gene (Adp53) on apoptosis and radiosensitivity of human gastric carcinoma cell lines. Methods: Recombinant adenovirus carrying wild-type p53 gene was transferred into four human gastric carcinoma cell lines with different p53 genetic status. P53 protein expression was detected by immunohistochemistry and Western blot assay. Cell survival was assessed using a clonogenic assay. TUNEL assay was used in determination of apoptosis. The four human gastric carcinoma cell line infected with Adp53 were irradiated with 4 Gy, and cell cycle distribution and apoptotic rate were assayed by flow cytometry. Nude mice xenograft models of W and M cell were intratumorally injected with Adp53 and 48 h later were irradiated with 6 Gy. Relative volume in growth curve of tumor was used to observe tumor regression. Results: G2/M arrest, apoptosis and inhibition of tumor cell proliferation were induced by infection with Adp53 at 100 MOI, which caused high transfer rate of wild-type p53 and strong expression of P53 protein in the four human gastric carcinoma cell line cells. When evaluating radio-biologic efficacy by apoptotic rate, the apoptotic enhancement ratio of Adp53 at 4 Gy was 3.0 for W cell, 3.6 for M cell, 2.2 for neo cell and 2.5 for 823 cell respectively, in vitro. The antitumor enhancement ratio of Adp53 at 6 Gy was 1.41 for cell-implanted tumor and 1.91 for M cell-implanted tumor in vivo. Conclusion: This study demonstrated that Adp53 transfer increased cellular apoptosis and radiosensitivity of human gastric carcinoma

  15. Radiosensitivity and ras oncogene expression in preneoplastic rat tracheal epithelial cells

    International Nuclear Information System (INIS)

    The sensitivity of preneoplastic rat tracheal epithelial (RTE) cells to the cytotoxic effects of high- and low-LET radiation, and the modulating effect of the viral ras oncogene on this sensitivity were determined. Two lines of preneoplastic RTE cells have the same responsiveness to high-LET radiation, but differ in their responsiveness to a transfected ras oncogene and in their sensitivities to low-LET radiation. Cells that respond to ras by becoming neoplastic are more resistant to the cytotoxic effects of low-LET radiation than cells that are not transformable by ras. The radiosensitivity of ras-responsive cells was not altered by transfection with ras. However, transfection of ras-non responsive cells with ras decreased their sensitivity to low-LET radiation. These data suggest that the ability of cells to repair radiation damage changes as they progress to neoplasia. (author)

  16. Ectopically hTERT expressing adult human mesenchymal stem cells are less radiosensitive than their telomerase negative counterpart

    DEFF Research Database (Denmark)

    Serakinci, Nedime; Christensen, Rikke; Graakjaer, Jesper;

    2007-01-01

    During the past several years increasing evidence indicating that the proliferation capacity of mammalian cells is highly radiosensitive, regardless of the species and the tissue of origin of the cells, has accumulated. It has also been shown that normal bone marrow cells of mice have a similar r...... high telomerase activity have the advantage of re-establishing the telomeric caps...

  17. Radiosensitization by 6-aminonicotinamide and 2-deoxy-D-glucose in human cancer cells.

    Science.gov (United States)

    Varshney, R; Dwarakanath, Bs; Jain, V

    2005-05-01

    The aim was to exploit simultaneous inhibition of glycolytic and pentose phosphate pathways of energy production for radiosensitization using 2-deoxy-D-glucose (2-DG) and 6-aminonicotinamide (6-AN) in transformed mammalian cells. Two human tumour cell lines (cerebral glioma, BMG-1 and squamous carcinoma cells 4197) were investigated. 2-DG and/or 6-AN added at the time of irradiation were present for 4 h after radiation. Radiation-induced cell death (macrocolony assay), cytogenetic damage (micronuclei formation), cell cycle delay (bromodeoxyuridne (BrdU) pulse chase), apoptosis (externalization of phosphotidylserine (PS) by annexin V), chromatin-bound proliferation cell nuclear antigen (PCNA) and cellular glutathione (GSH) levels were investigated as parameters of radiation response. The presence of 2-DG (5 mM) during and for 4 h after irradiation increased the radiation-induced micronuclei formation and cell death, and caused a time-dependent decrease in GSH levels in BMG-1 cells while no significant effects could be observed in 4197 cells. 6-AN (5 microM) enhanced the radiosensitivity of both cell lines and reduced the GSH content by nearly 50% in gamma-irradiated 4197 cells. Combining 2-DG and 6-AN caused a profound decrease in the GSH content and enhanced the radiation damage in both the cell lines by increasing mitotic and apoptotic cell death. Further, the combination (2-DG + 6-AN) enhanced the radiation-induced G2 block, besides arresting cells in S phase and inhibited the recruitment of PCNA. The combination of 2-DG and 6-AN enhances radiation damage by modifying damage response pathways and has the potential for improving radiotherapy of cancer. PMID:16076755

  18. EGFR and its mutant EGFRvIII as modulators of tumor cell radiosensitivity

    International Nuclear Information System (INIS)

    Purpose: Exposure of human carcinoma and malignant glioma cells to ionizing radiation (IR)activates EGFR,which as a consequence mediates a cytoprotective response. We have demonstrated that expression of a dominant negative mutant, EGFR-CD533 disrupts this cytoprotective response, resulting in significant radiosensitization. During studies of in vivo radiosensitization with intratumoral delivery of the Adenovirus (Ad) vector, Ad-EGFR-CD533, it became apparent that xenografts from human carcinoma and malignant glioma cells invariably expressed the constitutively active EGFR mutant, EGFRvIII. This mutant EGFRvIII is frequently found in vivo in glioblastoma, breast, prostate, lung and ovarian carcinoma, but does not appear to be expressed in tumor cells under in vitro conditions. The functional consequences of EGFRvIII expression on tumor cell radiation responses are currently unknown. We have therefore investigated in a transient transfection cell system the responses of EGFRvIII and downstream signal transduction pathways to IR. In addition, the capacity of EGFR-CD533 to disrupt the function of EGFRvIII was tested. Materials and Methods: The MDA-MB-231, U-87 MG and U-373 MG cell lines were established as tumors and then intratumorally transduced with Ad-EGFR-CD533 or Ad-LacZ (control vector). The transduction efficiency was > 40% in MDA-MB-231 tumors and reached > 70% in the glioma xenografts. Radiosensitivity was measured by ex vivo colony formation and growth delay assays. The functional consequences of EGFRvIII expression on cellular IR responses were studied in transiently transfected Chinese hamster ovary (CHO) cells because tumor cells do not express EGFRvIII in vitro. Transfection with null vectors and vectors encoding either EGFRvIII or EGFR were performed and similar protein expression levels were verified by Western blot analyses. Results: The radiosensitivity of Ad-EGFR-CD533 transduced tumors was significantly increased compared with Ad-LacZ transduced

  19. Effect of E1A gene on radiosensitivity of human laryngeal carcinoma cells and its correlated mechanisms

    International Nuclear Information System (INIS)

    Objective: To investigate the effect of E1A gene on the radiosensitivity of human laryngeal carcinoma cells and its correlated mechanisms. Methods: The Ad-E1A and Ad-β-gal were amplificated in Hek293 cells, extracted by freezing(-80 degree C) and thawing (37 degree C) repeatedly (3 times), purificated by the method of density gradient of CsCl and titrated by plaque assay method. Then they were transfected into human laryngeal carcinoma cells (Hep-2) and authenticated by RT-PCR. The radiosensitivity of Hep-2 cells transfected with or without E1A were studied by cell survival curve. Finally we investigated the correlated mechanisms including cell apoptosis studied by flow cytometry and VEGF content studied by RT-PCR. Results: The radiosensitivity of Hep-2 cells transfected with E1A was intensified, D0 and Dq were lowered and α was increased. Flow cytometry showed that the apoptosis rate of cells with E1A or with E1A and radiotherapy was increased. The VEGF content of the cells transfected with E1A or treated by radiotherapy was decreased, which reached the lowest level when the cells were treated with the both methods. Conclusions: E1A gene can intensify the radiosensitivity and contribute to the apoptosis of human laryngeal carcinoma cells. E1A gene and radiotherapy can markedly decrease the VEGF content. (authors)

  20. High radiosensitivity of the MOLT-4 leukaemic cell line

    International Nuclear Information System (INIS)

    Radiation survival of MOLT-4, a leukaemic T-lymphocyte cell line, was measured by counting colonies formed in 0.8% methyl cellulose. The survival curve was a simple exponential and showed the cells to be radiation sensitive, with D0=0.49+-0.02 Gy and extrapolation number n=0.92+-0.09. No increase in survival as measured by colony-forming ability or trypan blue dye exclusion was seen when the dose was split into two fractions, separated by a 5 h incubation period. Electron microscopy and trypan blue dye exclusion showed that 5 h after exposure to high doses, MOLT-4 cells began to die and displayed condensed, marginated chromatin and cellular vesticulation. (author)

  1. Effect of primarily cultured human lung cancer-associated fibroblasts on radiosensitivity of lung cancer cells

    International Nuclear Information System (INIS)

    Objective: To investigate the effect of human lung cancer-associated fibroblasts (CAF) on the radiosensitivity of lung cancer cells when CAF is placed in direct contact co-culture with lung cancer cells. Methods: Human lung CAF was obtained from fresh human lung adenocarcinoma tissue specimens by primary culture and subculture and was then identified by immunofluorescence staining. The CAF was placed in direct contact co-culture with lung cancer A549 and H1299 cells, and the effects of CAF on the radiosensitivity of A549 and H1299 cells were evaluated by colony-forming assay. Results: The human lung CAF obtained by adherent culture could stably grow and proliferate, and it had specific expression of α-smooth muscle actin, vimentin, and fibroblast activation protein,but without expression of cytokeratin-18. The plating efficiency (PE, %) of A549 cells at 0 Gy irradiation was (20.0 ± 3.9)% when cultured alone versus (32.3 ± 5.5)% when co-cultured with CAF (t=3.16, P<0.05), and the PE of H1299 cells at 0 Gy irradiation was (20.6 ± 3.1)% when cultured alone versus (35.2 ± 2.3)% when co-cultured with CAF (t=6.55, P<0.05). The cell survival rate at 2 Gy irradiation (SF2) of A549 cells was 0.727 ±0.061 when cultured alone versus 0.782 ± 0.089 when co-cultured with CAF (t=0.88, P>0.05), and the SF2 of H1299 cells was 0.692 ±0.065 when cultured alone versus 0.782 ± 0.037 when co-cultured with CAF (t=2.08, P>0.05). The protection enhancement ratios of human lung CAF for A549 cells and H1299 cells were 1.29 and 1.25, respectively. Conclusions: Human lung CAF reduces the radiosensitivity of lung cancer cells when placed in direct contact co-culture with them, and the radioprotective effect may be attributed to CAF promoting the proliferation of lung cancer cells. (authors)

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

    International Nuclear Information System (INIS)

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

  3. Nano-diamond as a multimodal platform for drug delivery and radiosensitization of tumor cells

    International Nuclear Information System (INIS)

    Nano-diamonds (NDs) are often considered as inert platforms with high interests for biomedical applications. They are well adapted for drug delivery, and may display embedded fluorescence. We report here on a new way to consider these nano-carbon particles, by revealing therapeutic capacities coming from electronic properties of NDs. With an optimized surface chemistry, the generation of Reactive Oxygen Species (ROS) occurs when those hydrogen-terminated NDs are exposed to photon irradiation, thus opening up the field towards the radiosensitization of tumor cells. (authors)

  4. The molecule HLA-G: radiosensitivity indicator of a human melanoma cell line

    International Nuclear Information System (INIS)

    The physiological and pathological relevance of the HLA-G molecule (non-classical Human Leukocyte Antigen) has been motif of important research studies. Its distribution is restricted to only few tissues. HLA-G takes part in the implantation after in vitro fecundation, in graft tolerance, in auto-immune diseases, and in tumoral immune escape. Its expression has been demonstrated in more than 30% of tumors of 15 different histological types. Gamma radiation modulates HLA-G expression at the cell surface. However, its involvement in tumoral radiosensitivity has not been demonstrated yet. The objective of this work was to demonstrate if the HLA-G molecule intervenes in the radiosensibility of human melanoma cells cultured in vitro. For this purpose we used the human melanoma cell line M8, which was transfected with the plasmid containing the HLA-G gene (M8 HLA-G+) or with the plasmid alone, without the HLA-G gene (M8 pc DNA). Both cell lines were irradiated with 0, 2, 5 y 10 Gy and in all cases survival frequency was determined with the clonogenic assay. We observed a significant reduction in M8 HLA-G+ survival with respect to M8 pc DNA for all irradiation doses and was independent of doses. These results, if confirmed in other histological types, could postulate the HLA-G molecule as a tumoral radiosensitivity marker. The specific mechanism involved in the radiosensibility modification exerted by HLA-G has not been elucidated yet. (authors)

  5. Cancer stem cells: The potential of carbon ion beam radiation and new radiosensitizers (Review).

    Science.gov (United States)

    Baek, Sung-Jae; Ishii, Hideshi; Tamari, Keisuke; Hayashi, Kazuhiko; Nishida, Naohiro; Konno, Masamitsu; Kawamoto, Koichi; Koseki, Jun; Fukusumi, Takahito; Hasegawa, Shinichiro; Ogawa, Hisataka; Hamabe, Atsushi; Miyo, Masaaki; Noguchi, Kozo; Seo, Yuji; Doki, Yuichiro; Mori, Masaki; Ogawa, Kazuhiko

    2015-11-01

    Cancer stem cells (CSCs) are a small population of cells in cancer with stem-like properties such as cell proliferation, multiple differentiation and tumor initiation capacities. CSCs are therapy-resistant and cause cancer metastasis and recurrence. One key issue in cancer therapy is how to target and eliminate CSCs, in order to cure cancer completely without relapse and metastasis. To target CSCs, many cell surface markers, DNAs and microRNAs are considered as CSC markers. To date, the majority of the reported markers are not very specific to CSCs and are also present in non-CSCs. However, the combination of several markers is quite valuable for identifying and targeting CSCs, although more specific identification methods are needed. While CSCs are considered as critical therapeutic targets, useful treatment methods remain to be established. Epigenetic gene regulators, microRNAs, are associated with tumor initiation and progression. MicroRNAs have been recently considered as promising therapeutic targets, which can alter the therapeutic resistance of CSCs through epigenetic modification. Moreover, carbon ion beam radiotherapy is a promising treatment for CSCs. Evidence indicates that the carbon ion beam is more effective against CSCs than the conventional X-ray beam. Combination therapies of radiosensitizing microRNAs and carbon ion beam radiotherapy may be a promising cancer strategy. This review focuses on the identification and treatment resistance of CSCs and the potential of microRNAs as new radiosensitizers and carbon ion beam radiotherapy as a promising therapeutic strategy against CSCs. PMID:26330103

  6. Alterations in growth phenotype and radiosensitivity after fractionated irradiation of breast carcinoma cells from a single patient

    International Nuclear Information System (INIS)

    The purpose was to investigate growth regulation and radiosensitivity in surviving clonogens after fractionated irradiation. Four breast carcinoma cell lines isolated from the primary tumor (21NT, 21PT) and metastases (21MT-1, 21MT-2) of a single patient were exposed to cumulative radiation doses of 30 Gy yielding cell lines designated -IR with respect to their parent. The irradiated lines were then compared to their parent for serum- and growth factor-requirements under defined media conditions, ability to proliferate in soft agar, concentration of TGF-alpha in conditioned medium, and radiosensitivity. The irradiated lines showed no change in proliferative doubling times under serum- and growth factor-supplemented media conditions. A single line, 21MT-1-IR, acquired a limited ability to proliferate in serum- and growth factor-deplete medium with a day 2-4 doubling time of 44.5 hr. Three lines, 21MT-1-IR, 21MT-2-IR, and 21NT-IR, formed colonies in soft agar in contrast to none of the unirradiated parent lines. There were significant 6-8 fold increases in conditioned media TGF-alpha concentrations for 21MT-2-IR and 21NT-IR cells. The 21MT-1-IR and 21NT-IR cells were significantly less radiosensitive than their respective parent lines. This decrease in radiosensitivity appeared to be at least partially mediated by a released factor as the radiosensitivity of 21MT-1 cells was significantly decreased by pre-incubation with conditioned medium from 21MT-1-IR cells. Radiation-induced changes in growth phenotype vary with respect to clonal origin of the cell line and may influence the radiosensitivity of surviving clonogens after fractionated treatment. 18 refs., 4 figs., 3 tabs

  7. Radiosensitivity of hyperpentaploid cell cloni in carcinoma of the vulva

    International Nuclear Information System (INIS)

    In November 1993 a 83-year old patient with a carcinoma of the vulva was introduced to the Strahlenklinik der Staedtischen Kliniken Offenbach. It was a stage T3N0M0 tumor (UICC 1990). We performed daily smears of the tumor surface during radiotherapy. The smears became air-dried before fixation in PBS/formaldehyde and staining with the Feulgen procedure. The DNA-analyse took place at an image-analysis-system (Ahrens Cytometry Analyse System). Nine and 16 weeks after radiotherapy the patient showed clinically complete remission. Macroscopically and histopathologically there was no tumor found. The ploidy-analysis shows the take off of the hyperpentaploid cells on radiotherapy. Nine and 16 weeks after finished therapy there are no more hyperpentaploid cells detectable. (orig.)

  8. Mechanisms of radiosensitization and protection studied with glutathione-deficient human cell lines

    International Nuclear Information System (INIS)

    Glutathione-deficient fibroblasts and lymphoblastoid cells, derived from patients with an inborn error of glutathione synthetase activity, and glutathione-proficient cells, derived from clinically healthy individuals, were used to investigate the importance of glutathione for radiosensitization by misonidazole. With single-strand DNA breaks as an end point, misonidazole as well as oxygen was found to lack any sensitizing effect on cells deficient in glutathione. The post-irradiation repair of single-strand breaks induced by hypoxic irradiation of misonidazole treated cells was found to be a great extent glutathione dependent, like the repair of breaks induced by oxic irradiation. Naturally occurring aminothiols in glutathione-deficient cells appeared to be in efficient as substitutes for glutatione. Artificial aminothiols, such as cysteamine or dithiothreitol, were found to effectively replace glutathione

  9. Increased betulinic acid induced cytotoxicity and radiosensitivity in glioma cells under hypoxic conditions

    International Nuclear Information System (INIS)

    Betulinic acid (BA) is a novel antineoplastic agent under evaluation for tumor therapy. Because of the selective cytotoxic effects of BA in tumor cells (including gliomas), the combination of this agent with conservative therapies (such as radiotherapy and chemotherapy) may be useful. Previously, the combination of BA with irradiation under hypoxic conditions had never been studied. In this study, the effects of 3 to 30 μM BA on cytotoxicity, migration, the protein expression of PARP, survivin and HIF-1α, as well as radiosensitivity under normoxic and hypoxic conditions were analyzed in the human malignant glioma cell lines U251MG and U343MG. Cytotoxicity and radiosensitivity were analyzed with clonogenic survival assays, migration was analyzed with Boyden chamber assays (or scratch assays) and protein expression was examined with Western blot analyses. Under normoxic conditions, a half maximal inhibitory concentration (IC50) of 23 μM was observed in U251MG cells and 24 μM was observed in U343MG cells. Under hypoxic conditions, 10 μM or 15 μM of BA showed a significantly increased cytotoxicity in U251MG cells (p = 0.004 and p = 0.01, respectively) and U343MG cells (p < 0.05 and p = 0.01, respectively). The combination of BA with radiotherapy resulted in an additive effect in the U343MG cell line under normoxic and hypoxic conditions. Weak radiation enhancement was observed in U251MG cell line after treatment with BA under normoxic conditions. Furthermore, under hypoxic conditions, the incubation with BA resulted in increased radiation enhancement. The enhancement factor, at an irradiation dose of 15 Gy after treatment with 10 or 15 μM BA, was 2.20 (p = 0.02) and 4.50 (p = 0.03), respectively. Incubation with BA led to decreased cell migration, cleavage of PARP and decreased expression levels of survivin in both cell lines. Additionally, BA treatment resulted in a reduction of HIF-1α protein under hypoxic conditions. Our results suggest that BA is capable of

  10. Use of single cell micro-gel electrophoresis to detect the cellular radiosensitivity of two fibroblast strains

    International Nuclear Information System (INIS)

    Single cell micro-gel electrophoresis (SCGE) and MTT assay were used to determine the relationships between radiation-induced initial DNA double-strand breaks (DSBs), the ability of cells to repair DSBs and cellular radiosensitivity in both AT5BIVA and GM637 cell lines. The results demonstrated that AT5BIVA cell line was significantly more radiosensitive than GM637. The initial DSBs in both AT5BIVA and GM637 lines increased with the rise of irradiation dose, and showed significant dependence on dose. At a given dose of 20 Gy, radiation-induced initial DSBs in AT5BIVA cell line was significantly higher than those in GM637. The ability of AT5BIVA cell line to repair DSBs was more powerful than that of GM637. The results suggested that the radiation-induced initial DSBs in cells and the ability of cells to repair DSBs both correlated with cellular radiosensitivity to a certain extent, and could be used as potential predictors of intrinsic radiosensitivity of cells

  11. Constitutive NF-κB activity influences basal apoptosis and radiosensitivity of head-and-neck carcinoma cell lines

    International Nuclear Information System (INIS)

    Purpose: Nuclear factor-κB (NF-κB) has been implicated in anti-apoptotic gene transactivation, according to its transcriptional activity. The present study was designed to investigate whether constitutive NF-κB activity could modulate basal apoptosis and intrinsic radiosensitivity of KB head-and-neck carcinoma cell line and KB3 subline. The KB3 subline was more radiosensitive (SF2=0.48, α=0.064) than the radioresistant KB parental cell line (SF2=0.80, α=0.114). Methods and Materials: Constitutive NF-κB DNA-binding activity was determined using electrophoretic mobility shift assay. Modulation of NF-κB activity was performed by exposing both cell lines to tumor necrosis factor α or dexamethasone. Apoptotic cell population was analyzed using flow cytometry (annexin V/propidium iodide). Radiosensitivity was assessed from determination of the surviving fraction at 2 Gy (SF2), and α and β parameters were determined using the linear-quadratic model. Results: Constitutive NF-κB activity was found to be significantly lower in KB3 than in KB. KB cell line exposure to dexamethasone significantly decreased NF-κB DNA-binding activity and, consequently, enhanced baseline apoptosis and radiosensitivity (α values: 0.114 vs. 0.052). Conversely, exposure of KB3 cells to tumor necrosis factor α increased NF-κB DNA-binding activity and resulted in a significant decrease (50%) in rate of apoptosis and in radiosensitivity (SF2 values: 0.48 vs. 0.63). Conclusions: Modulation of NF-κB DNA-binding activity influences baseline apoptosis and intrinsic radiosensitivity

  12. Icaritin synergistically enhances the radiosensitivity of 4T1 breast cancer cells.

    Directory of Open Access Journals (Sweden)

    Jinsheng Hong

    Full Text Available Icaritin (ICT is a hydrolytic form of icariin isolated from plants of the genus Epimedium. This study was to investigate the radiosensitization effect of icaritin and its possible underlying mechanism using murine 4T1 breast cancer cells. The combination of Icaritin at 3 µM or 6 µM with 6 or 8 Gy of ionizing radiation (IR in the clonogenic assay yielded an ER (enhancement ratio of 1.18 or 1.28, CI (combination index of 0.38 or 0.19 and DRI (dose reducing index of 2.51 or 5.07, respectively. These strongly suggest that Icaritin exerted a synergistic killing (? effect with radiation on the tumor cells. This effect might relate with bioactivities of ICT: 1 exert an anti-proliferative effect in a dose- and time-dependent manner, which is different from IR killing effect but likely work together with the IR effect; 2 suppress the IR-induced activation of two survival paths, ERK1/2 and AKT; 3 induce the G2/M blockage, enhancing IR killing effect; and 4 synergize with IR to enhance cell apoptosis. In addition, ICT suppressed angiogenesis in chick embryo chorioallantoic membrane (CAM assay. Taken together, ICT is a new radiosensitizer and can enhance anti-cancer effect of IR or other therapies.

  13. Radiosensitization of Non-Small Cell Lung Cancer Cells by Inhibition of TGF-β1 Signaling With SB431542 Is Dependent on p53 Status.

    Science.gov (United States)

    Zhao, Yifan; Wang, Longxiao; Huang, Qianyi; Jiang, Youqin; Wang, Jingdong; Zhang, Liyuan; Tian, Ye; Yang, Hongying

    2016-01-01

    Although medically inoperable patients with stage I non-small cell lung cancer cells (NSCLC) are often treated with stereotactic body radiation therapy, its efficacy can be compromised due to poor radiosensitivity of cancer cells. Inhibition of transforming growth factor-β1 (TGF-β1) using LY364947 and LY2109761 has been demonstrated to radiosensitize cancer cells such as breast cancer, glioblastoma, and lung cancer. Our previous results have demonstrated that another potent and selective inhibitor of TGF-β1 receptor kinases, SB431542, could radiosensitize H460 cells both in vitro and in vivo. In the present study, we investigated whether SB431542 could radiosensitize other NSCLC cell lines, trying to explore the potential implication of this TGF-β1 inhibitor in radiotherapy for NSCLC patients. The results showed that A549 cells were significantly radiosensitized by SB431542, whereas no radiosensitizing effect was observed in H1299 cells. Interestingly, both H460 and A549 cells have wild-type p53, while H1299 cells have deficient p53. To study whether the radiosensitizing effect of SB431542 was associated with p53 status of cancer cells, the p53 of H460 cells was silenced using shRNA transfection. Then it was found that the radiosensitizing effect of SB431542 on H460 cells was not observed in H460 cells with silenced p53. Moreover, X-irradiation caused rapid Smad2 activation in H460 and A549 cells but not in H1299 and H460 cells with silenced p53. The Smad2 activation postirradiation could be abolished by SB431542. This may explain the lack of radiosensitizing effect of SB431542 in H1299 and H460 cells with silenced p53. Thus, we concluded that the radiosensitizing effect of inhibition of TGF-β1 signaling in NSCLC cells by SB431542 was p53 dependent, suggesting that using TGF-β1 inhibitor in radiotherapy may be more complicated than previously thought and may need further investigation. PMID:27178816

  14. Further studies on the possible relationship between radiation-induced reciprocal translocations and intrinsic radiosensitivity of human tumor cells

    International Nuclear Information System (INIS)

    Background and purpose. The aim of the present study was to estimate yields of radiation-induced translocations in surviving cells of several human tumor cell lines and in normal diploid human fibroblasts, and to compare these yields with corresponding intrinsic radiosensitivities determined by standard colony-formation assay. Material and methods. The yields of radiation-induced reciprocal translocations were investigated by fluorescence in situ hybridization. Chromosomes no. 1 and no. 4 were 'painted' with fluorescent hybridization probes for whole chromosomes. Translocation yields and cell survival were determined for different doses up to 6 Gy of 200 kV X-rays. Results. We observed a higher frequency of reciprocal translocations in the radiosensitive cells MCF-7 and MDA-MB-436 than in the radioresistant cells CaSki, WiDr, A549 and normal skin fibroblasts. For primary squamous cell carcinoma cells, ZMK-1, an intermediate radiosensitivity and an intermediate translocation yield were observed. The dose-dependence of translocation yields involving chromosomes no. 1 or no. 4 varied in different cell lines: it was linear or linear with a plateau at higher doses. Conclusions. A comparison of the data obtained with chromosomes no. 1 and no. 4 in the investigated cell types, indicates that intrinsic radiosensitivity of different tumor cells observed at the survival level, is correlated with different translocation yields, respectively. This correlation was observed for all cell types investigated, independent of the number of copies of the painted chromosome per cell or the radiation dose. However, for low doses (under 1 Gy), the yields of translocations determined for the individual chromosomes seem to be too low for a discrimination between radioresistant or radiosensitive cells

  15. The one-cell mouse embryo: cell cycle-dependent radiosensitivity and development of chromosomal anomalies in postradiation cell cycles

    International Nuclear Information System (INIS)

    One-cell mouse embryos were irradiated with X-rays at different cell cycle stages. Examination of structural chromosomal anomalies and micronucleus formation in postradiation mitoses and interphases demonstrated cell cycle-dependent radiosensitivities in the order: late G2 phase > G1 phase > S phase > early G2 phase > stage of decondensing nuclei. Comparison of the quality and quantity of chromosomal aberrations from the first to third mitosis led to the conclusion that new chromosomal anomalies were formed in the course of postirradiation cell cycles. This hypothesis was supported by an increasing number of micronuclei from 24 to 48 h post-conception. In addition to structural chromosomal aberrations, radiation-induced chromosome loss was observed with a frequency that was obviously independent of the exposed cell cycle phase. Loss of acentric chromosome fragments and of single chromosomes contributed to the micronucleus formation. (author)

  16. Differences in heat-induced cell killing as determined in three mammalian cell lines do not correspond with the extent of heat radiosensitization

    Energy Technology Data Exchange (ETDEWEB)

    Kampinga, H.H.; Jorritsma, J.B.M.; Burgman, P.; Konings, A.W.T.

    1986-10-01

    Three different cell lines, Ehrlich ascites tumour (EAT) cells, HeLa S/sub 3/ cells and LM mouse fibroblasts, were used to investigate whether or not the extent of heat killing (44/sup 0/C) and heat radio-sensitization (44/sup 0/C before 0-6 Gy X-irradiation) are related. Although HeLa cells were the most heat-resistant cell line and showed the least heat radiosensitization, we found that the most heat-sensitive EAT cells (D/sub 0/, EAT = 8.0 min; D/sub 0/, LM = 10.0 min; D/sub 0/, HeLa = 12.5 min) showed less radiosensitization than the more heat-resistant LM fibroblasts (TERsub(HeLa)cell death are not identical to those determining heat radiosensitization. Furthermore the inactivation of DNA polymerase ..cap alpha.. and ..beta.. activities by heat seemed not to correlate with heat survival alone but showed a positive relationship to heat radiosensitization. The possibility of these enzymes being a determinant in heat radiosensitization is discussed.

  17. Differences in heat-induced cell killing as determined in three mammalian cell lines do not correspond with the extent of heat radiosensitization.

    Science.gov (United States)

    Kampinga, H H; Jorritsma, J B; Burgman, P; Konings, A W

    1986-10-01

    Three different cell lines, Ehrlich ascites tumour (EAT) cells, HeLa S3 cells and LM mouse fibroblasts, were used to investigate whether or not the extent of heat killing (44 degrees C) and heat radio-sensitization (44 degrees C before 0-6 Gy X-irradiation) are related. Although HeLa cells were the most heat-resistant cell line and showed the least heat radiosensitization, we found that the most heat-sensitive EAT cells (D0, EAT = 8.0 min; D0, LM = 10.0 min; D0, HeLa = 12.5 min) showed less radiosensitization than the more heat-resistant LM fibroblasts (TERHeLa less than TEREAT less than TERLM). Therefore, it is concluded that the routes leading to heat-induced cell death are not identical to those determining heat radiosensitization. Furthermore the inactivation of DNA polymerase alpha and beta activities by heat seemed not to correlate with heat survival alone but showed a positive relationship to heat radiosensitization. The possibility of these enzymes being a determinant in heat radiosensitization is discussed. PMID:3489689

  18. Differences in heat-induced cell killing as determined in three mammalian cell lines do not correspond with the extent of heat radiosensitization

    International Nuclear Information System (INIS)

    Three different cell lines, Ehrlich ascites tumour (EAT) cells, HeLa S3 cells and LM mouse fibroblasts, were used to investigate whether or not the extent of heat killing (440C) and heat radio-sensitization (440C before 0-6 Gy X-irradiation) are related. Although HeLa cells were the most heat-resistant cell line and showed the least heat radiosensitization, we found that the most heat-sensitive EAT cells (D0, EAT = 8.0 min; D0, LM = 10.0 min; D0, HeLa = 12.5 min) showed less radiosensitization than the more heat-resistant LM fibroblasts (TERsub(HeLa)< TERsub(EAT)< TERsub(LM)). Therefore, it is concluded that the routes leading to heat-induced cell death are not identical to those determining heat radiosensitization. Furthermore the inactivation of DNA polymerase α and β activities by heat seemed not to correlate with heat survival alone but showed a positive relationship to heat radiosensitization. The possibility of these enzymes being a determinant in heat radiosensitization is discussed. (author)

  19. MicroRNA-148b enhances the radiosensitivity of non-Hodgkin's Lymphoma cells by promoting radiation-induced apoptosis

    OpenAIRE

    Wu, Y.; Liu, G.-L.; Liu, S.-H.; Wang, C.-X.; Xu, Y.-L.; Ying, Y; Mao, P.

    2012-01-01

    Growing evidence has demonstrated that microRNAs (miRNAs) play an important role in regulating cellular radiosensitivity. This study aimed to explore the role of miRNAs in non-Hodgkin's lymphoma (NHL) radiosensitivity. Microarray was employed to compare the miRNA expression profiles in B cell lymphoma cell line Raji before and after a 2-Gy dose of radiation. A total of 20 differentially expressed miRNAs were identified including 10 up-regulated and 10 down-regulated (defined as P 

  20. Radiosensitization of pancreatic cancer cells by 2',2'-difluoro-2'-deoxycytidine

    International Nuclear Information System (INIS)

    Purpose: We have reported that the deoxycytidine analog 2',2'-difluoro-2'-deoxycytidine (dFdCyd) is a potent radiosensitizer of HT29 human colon cancer cells probably through its effects on intracellular deoxyribonucleotide (dNTP) pools. Because dFdCyd has activity against pancreatic cancer in clinical trials, we wished to determine if dFdCyd would radiosensitize human pancreatic cancer cells. Methods and Materials: We assessed the effect of dFdCyd on radiation sensitivity of two human pancreatic cancer cell lines, Panc-1 and BxPC-3. To begin to investigate the mechanism of sensitization, we determined the effect of dFdCyd on dNTP pools and cell cycle distribution. Results: We found that dFdCyd produced radiation enhancement ratios of 1.7-1.8 under noncytotoxic conditions in both cell lines. Sensitization was not associated with intracellular levels of 2',2'-difluoro-2'-deoxycytidine triphosphate, the cytotoxic metabolite of dFdCyd, but occurred when dATP pools were depleted below the level of approximately 1 μM. Although both cell lines showed substantial cell cycle redistribution after drug treatment, the flow cytogram of the BxPC-3 cells would not, by itself, be anticipated to result in increased radiation sensitivity. Conclusions: These findings demonstrate that dFdCyd is a potent radiation sensitizer of human pancreatic cancer cells and support the development of a clinical protocol using combined dFdCyd and radiation therapy in the treatment of pancreatic cancer

  1. Radiosensitization of Human Leukemic HL-60 Cells by ATR Kinase Inhibitor (VE-821: Phosphoproteomic Analysis

    Directory of Open Access Journals (Sweden)

    Barbora Šalovská

    2014-07-01

    Full Text Available DNA damaging agents such as ionizing radiation or chemotherapy are frequently used in oncology. DNA damage response (DDR—triggered by radiation-induced double strand breaks—is orchestrated mainly by three Phosphatidylinositol 3-kinase-related kinases (PIKKs: Ataxia teleangiectasia mutated (ATM, DNA-dependent protein kinase (DNA-PK and ATM and Rad3-related kinase (ATR. Their activation promotes cell-cycle arrest and facilitates DNA damage repair, resulting in radioresistance. Recently developed specific ATR inhibitor, VE-821 (3-amino-6-(4-(methylsulfonylphenyl-N-phenylpyrazine-2-carboxamide, has been reported to have a significant radio- and chemo-sensitizing effect delimited to cancer cells (largely p53-deficient without affecting normal cells. In this study, we employed SILAC-based quantitative phosphoproteomics to describe the mechanism of the radiosensitizing effect of VE-821 in human promyelocytic leukemic cells HL-60 (p53-negative. Hydrophilic interaction liquid chromatography (HILIC-prefractionation with TiO2-enrichment and nano-liquid chromatography—tandem mass spectrometry (LC-MS/MS analysis revealed 9834 phosphorylation sites. Proteins with differentially up-/down-regulated phosphorylation were mostly localized in the nucleus and were involved in cellular processes such as DDR, all phases of the cell cycle, and cell division. Moreover, sequence motif analysis revealed significant changes in the activities of kinases involved in these processes. Taken together, our data indicates that ATR kinase has multiple roles in response to DNA damage throughout the cell cycle and that its inhibitor VE-821 is a potent radiosensitizing agent for p53-negative HL-60 cells.

  2. Radiosensitization of Chinese hamster cells by oxygen and misonidazole at low X-ray doses

    International Nuclear Information System (INIS)

    The radiosensitization of Chinese hamster V79 cells in vitro by air and misonidazole at low X-ray doses (0.2-6.0 Gy) has been studied. These survival data, with high-dose data, were fitted to the linear quadratic model ln S= -(αD + βD2), deriving estimates of α and β by six different methods to illustrate the influence of the statistical treatment on the values so derived. This study clearly demonstrated that the survival parameters α and β are dependent to some degree on the method of analysis of the raw survival data; however, their ratios, the values of oxygen enhancement ratios (OERs) and radiosensitizer enhancement ratios (SERs) derived from the different methods, are similar. All methods of analysis give reduced OERs at low radiation doses for combined low- and high-dose X-ray data. However, the OERs are still appreciably high, ranging from 2.45 to 2.50 for an oxic dose of 2 Gy. All methods of analysis gave reduced SERs at low doses for combined low and high X-ray dose data for hypoxic cells irradiated in 1 mmol dm-3 misonidazole. At survival levels corresponding to doses of 2 Gy in the presence of 1 mmol dm-3 misonidazole OERs and SERs ranged from 1.2 to 1.5. (author)

  3. Downregulation of high mobility group box 1 modulates telomere homeostasis and increases the radiosensitivity of human breast cancer cells.

    Science.gov (United States)

    Ke, Shaobo; Zhou, Fuxiang; Yang, Hui; Wei, Yuehua; Gong, Jun; Mei, Zijie; Wu, Lin; Yu, Haijun; Zhou, Yunfeng

    2015-03-01

    The functions of the high mobility group box 1 (HMGB1) in tumor cells include replenishing telomeric DNA and maintaining cell immortality. There is a negative correlation between human telomerase reverse transcriptase (hTERT) and radiosensitivity in tumor cells. Our aim was to elucidate the relationship among HMGB1, telomere homeostasis and radiosensitivity in MCF-7 cells. In this study, we established stably transfected control (MCF-7-NC) and HMGB1 knockdown (MCF-7-shHMGB1) cell lines. The expression of HMGB1 mRNA and the relative telomere length were examined by real-time PCR. Radiosensitivity was detected by clonogenic assay. The protein expressions were determined by western blot analysis. The telomerase activity was detected by PCR-ELISA. Proliferation ability was examined by CCK-8 assay. Cell cycle and apoptosis were examined by flow cytometry. DNA damage foci were detected by immunofluorescence. ShRNA-mediated downregulation of HMGB1 expression increased the radiosensitivity of MCF-7 cells, and reduced the accumulation of hTERT and cyclin D1. Moreover, knockdown of HMGB1 in MCF-7 cells inhibited telomerase activity and cell proliferation, while increasing the extent of apoptosis. Downregulation of HMGB1 modulated telomere homeostasis by changing the level of telomere-binding proteins, such as TPP1 (PTOP), TRF1 and TRF2. This downregulation also inhibited the ATM and ATR signaling pathways. The current data demonstrate that knockdown of HMGB1 breaks telomere homeostasis, enhances radiosensitivity, and suppresses the repair of DNA damage in human breast cancer cells. These results suggested that HMGB1 might be a potential radiotherapy target in human breast cancer. PMID:25501936

  4. Antitumor effects and radiosensitization of cytosine deaminase and thymidine kinase fusion suicide gene on colorectal carcinoma cells

    Institute of Scientific and Technical Information of China (English)

    De-Hua Wu; Li Liu; Long-Hua Chen

    2005-01-01

    AIM: To investigate the killing effect and radiosensitization of double suicide gene mediated by adenovirus on colorectal carcinoma cells.METHODS: Colorectal carcinoma cell line SW480 was transfected with adenovirus expression vector containing cytosine deaminase (CD) and thymidine kinase (Tk) fusion gene. The expression of CD-TK fusion gene was detected by reverse transcriptase-polymerase chain reaction. The toxic effect of ganciclovir (GCV) and 5-fiuorocytosine (5FC) on infected cells was determined by MTT assay. The radiosensitization of double suicide gene was evaluated by clonogenic assay.RESULTS: After prodrugs were used, the survival rate of colorectal carcinoma cells was markedly decreased. When GCV and 5-FC were used in combination, the cytotoxicity and bystandereffect were markedly superior to a single prodrug (x2 = 30.371, P<0.01). Both GCV and 5-FC could sensitize colorectal carcinoma cells to the toxic effect of radiation, and greater radiosensitization was achieved when both prodrug were used in combination. CONCLUSION: CD-TK double suicide gene can kill and radiosensitize colorectal carcinoma cells.

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

    International Nuclear Information System (INIS)

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

  6. A novel approach to sensitize solid tumor to radiosurgery by using hypoxic and proliferating-cell radiosensitizers

    International Nuclear Information System (INIS)

    There are two types of radiosensitizers have been used for clinical trial. Namely, halogenated pyrimidine (e.g. 5-iododeoxyuridine (IUdR)), and hypoxic cell radiosensitizers (e.g. misonidazole (MISO), etanidazole, etc.). However, there is no report of simultaneous application of these two radiosensitizers in research and clinical radiotherapy. In recent years, single dose stereotatic radiosurgery has been used for controlling metastatic lesions in the brain. In these lesions are composing of aerated cycling and hypoxic resting tumor cells. We proposed to used the above two types of radiosensitizers to enhance tumor control probability of the stereotactic radiosurgery. In this study, drugs such as IUdR and MISO were selected and C3H/HeN mice bearing KHT sarcoma were used for evaluation of biodistribution and effectiveness of these two radiosensitizers. The biodistribution of these two drugs was studied using gamma counting and autoradiographic techniques. The optimal effectiveness of these two drugs combined with radiation was evaluated by in vivo - in vitro clonogenic assay system. The biodistribution data obtained from gamma counting was similar to that obtained from autoradiography. Although the clearance rates of [131I] IUdR and [18F] FMISO were very rapid, the incorporation of [131I] IUdR into DNA of KHT sarcoma cells was very stable from 0.5 to 24 hours. The biodistribution of [131I] IUdR and [18F] FMISO as shown by macroautoradiography appeared that they were incorporated/bound to the different areas of the tumor. At 2 hours after quartic injection of IUdR followed by a single injection of MISO appears to be the optimal time for the combination with radiation. The enhancement ratio for MISO, IUdR and MISO + IUdR combined with radiation were 1.2, 1.3 and 1.55 respectively. These results demonstrated for the first time that a maximum radiosensitization effect was occurred using the above method of combination

  7. MiR-26a enhances the radiosensitivity of glioblastoma multiforme cells through targeting of ataxia–telangiectasia mutated

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    Guo, Pin; Lan, Jin; Ge, Jianwei; Nie, Quanmin; Guo, Liemei [Department of Neurosurgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127 (China); Qiu, Yongming, E-mail: qiuzhoub@hotmail.com [Department of Neurosurgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127 (China); Shanghai Institute of Head Trauma, Shanghai 200127 (China); Mao, Qing, E-mail: maoq@netease.com [Department of Neurosurgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127 (China); Shanghai Institute of Head Trauma, Shanghai 200127 (China)

    2014-01-15

    Glioblastoma multiforme (GBM) is notoriously resistant to radiation, and consequently, new radiosensitizers are urgently needed. MicroRNAs are a class of endogenous gene modulators with emerging roles in DNA repair. We found that overexpression of miR-26a can enhance radiosensitivity and reduce the DNA repair ability of U87 cells. However, knockdown miR-26a in U87 cells could act the converse manner. Mechanistically, this effect is mediated by direct targeting of miR-26a to the 3′UTR of ATM, which leads to reduced ATM levels and consequent inhibition of the homologous recombination repair pathway. These results suggest that miR-26a may act as a new radiosensitizer of GBM. - Highlights: ●miR-26a directly target ATM in GBM cells. ●miR-26a enhances the radiosensitivity of GBM cells. ●miR-26a could reduce the DNA repair capacity of GBM cells.

  8. MiR-26a enhances the radiosensitivity of glioblastoma multiforme cells through targeting of ataxia–telangiectasia mutated

    International Nuclear Information System (INIS)

    Glioblastoma multiforme (GBM) is notoriously resistant to radiation, and consequently, new radiosensitizers are urgently needed. MicroRNAs are a class of endogenous gene modulators with emerging roles in DNA repair. We found that overexpression of miR-26a can enhance radiosensitivity and reduce the DNA repair ability of U87 cells. However, knockdown miR-26a in U87 cells could act the converse manner. Mechanistically, this effect is mediated by direct targeting of miR-26a to the 3′UTR of ATM, which leads to reduced ATM levels and consequent inhibition of the homologous recombination repair pathway. These results suggest that miR-26a may act as a new radiosensitizer of GBM. - Highlights: ●miR-26a directly target ATM in GBM cells. ●miR-26a enhances the radiosensitivity of GBM cells. ●miR-26a could reduce the DNA repair capacity of GBM cells

  9. DNA supercoiling changes and nucleoid protein composition in a group of L5178Y cells of varying radiosensitivity

    International Nuclear Information System (INIS)

    Cells of the radioresistant L5178Y-R, -S35, -SR and M10(neo 5)-l and radiosensitive L5178Y-S, M10 and LX830 cell lines were used to investigate the relationship between radiosensitivity and DNA supercoiling ability mediated by the nuclear matrix within chromatin loops containing DNA damage. The ability of DNA loops to undergo changes in supercoiling in the presence of radiation-induced damage revealed that in all cases the degree of inhibition of supercoil rewinding was greater in the radiosensitive cells. Since the amount of DNA damage induced per unit dose is known to be equal in all these cell lines, the same number of DNA lesions produced a greater loss of topological constraint in the radiosensitive cells. The differential loss of DNA supercoiling ability could be due to differences in DNA-nuclear matrix anchor points. High-resolution two-dimensional gel electrophoresis of nucleoid proteins showed numerous reproducible differences in nuclear matrix protein between the cell lines studied. A total of nine proteins were associated with nucleoids from L5178Y-R cells and absent from L5178Y-S nucleoids. None of them, however, correlated absolutely with radioresistance. Thus, unlike previous studies in CHO cells, no candidates for the conveyance of cellular radiosensitivity that were single proteins were detected. However, these results are consistent with the hypothesis that stability of DNA loop domains in the presence of DNA damage is a determinant of the outcome of radiation-induced DNA damage. 21 refs., 3 figs., 1 tab

  10. 2-chloro-4-nitroimidazole radiosensitizers of hypoxic tumor cells in vivo

    International Nuclear Information System (INIS)

    The transplantable rhabdomyosarcoma in WAG/Rij rats was used to test the in vivo efficacy of 1-methyl-2-chloro-4-nitroimidazole (P13) and its analog 1-(2-hydroxy-3-methoxy-propyl)-2-chloro-4-nitroimidazole (P40) as tumor cell radiosensitizers after their i.p. low dose administration. The results indicate that both compounds administered repeatedly at nontoxic concentrations (70-150 mg/kg body wt.) in combination with moderate fractionated doses of irradiation (3.7 Gy) enhance the radiation effect on tumors. The local control of tumors on the 210th day in all experimental groups was higher than in the controls. In case of P40 administered in the maximal dose, the increment in local control was statistically significant (p<0.05). The re-growth delay was also greater after treatment with radiosensitizers. In the course of treatment no symptoms were observed of neurotoxicity of the compounds. The mean body weight of rats during the administration of the compounds remained on the level of control rats whose tumors were only irradiated. (author). 2 tabs., 15 refs

  11. Deficiency of DNA double-strand break repair and enhanced radiosensitivity in Tip60 silenced cells

    International Nuclear Information System (INIS)

    Objective: To investigate the effect of Tip60 on the cellular radiosensitivity,and to explore the related mechanism. Methods: siRNA and anacardic acid (AA, an inhibitor of Tip60 acetyltransferase) were used to inhibit Tip60 expression and its acetyltransferase activity, respectively. Radiosensitivity was analyzed by colony-forming ability assay. γ-H2AX foci were detected to analyze the DNA double-strand break (DSB). Immunoprecipitation was used to determine the interaction of proteins. Results: siRNA-mediated silencing of Tip60 led to enhanced sensitivity of U2OS cells at 1, 2 Gy after γ-ray irradiation, but had no significant effect at 4 Gy post-irradiation (t=3.364, 3.979, P<0.05).γ-H2AX foci detection indicated that Tip60 silencing resulted in a decreased capability of DNA double-strand break repair at 1, 4 and 8 h after irradiation (t=3.875, 3.183 and 3.175, respectively, P<0.05). The interaction of Tip60 and DNA-PKcs was prompted by ionizing radiation. Anacardic acid largely abrogated the phosphorylation of DNA-PKcs at T2609 site induced by irradiation. Conclusions: Tip60 plays a role in the cellular response to ionizing radiation-induced DNA damage through, at least in part, interacting with DNA-PKcs and regulating its phosphorylation. (authors)

  12. Effect of hypoxic cell radiosensitizers on glutathione level and related enzyme activities in isolated rat hepatocytes

    International Nuclear Information System (INIS)

    A comparative study of the effect of misonidazole and novel radiosensitizers on glutathione (GSH) levels and related enzyme activities in isolated rat hepatocytes was performed. Incubation of hepatocytes with 5 mM radiosensitizers led to a decrease in the intracellular GSH level. The most pronounced decrease in cellular GSH was evoked by 2,4-dinitromidazole-1-ethanol (DNIE); after incubation for only 15 min, GSH was hardly detected. DNIE-mediated GSH loss was dependent upon its concentration. DNIE reacted with GSH nonenzymatically as well as with diethylmaleate, while misonidazole and 1-methyl-2-methyl-sulfinyl-5-methoxycarbonylimidazole (KIH-3) did not. Addition of partially purified glutathione S-transferase (GST) did not enhance DNIE-mediated GSH loss in a cell-free system. DNIE inhibited glutathione peroxidase (GSH-Px), GST, and glutathione reductase (GSSG-R) activities in hepatocytes, while misonidazole and KIH-3 did not. GSH-Px activity assayed with H2O2 as substrate was the most inhibited. Inhibition of GSH-Px activity assayed with cumene hydroperoxide as substrate and GST was less than that of GSH-Px assayed with H2O2 as substrate. GSSG-R activity was decreased by DNIE, but not significantly. Incubation of purified GSH-Px with DNIE resulted in a little change in the activity when assayed with H2O2 as substrate. 26 references, 2 figures, 4 tables

  13. Potentiation of radiosensitivity by tetrandrine in human breast cancer cells and its mechanism

    International Nuclear Information System (INIS)

    Objective: To investigate the potentiation of radiosensitivity and mechanism by tetrandrine (Tet) in human breast cancer p53-mutant MCF-7/ADR and p53-wt MCF-7 cells. Methods: Clonogenic assay, flow cytometry, Western blotting were preformed in this experiment. Results: The data of clonogenic assay showed that Tet markedly sensitized MCF-7/ADR cell to X-rays, and the sensitization enhancement ratio (SER) of Tet was 1.51. Flow cytometry assay showed that exposure of MCF-7/ADR cells to X-rays caused cells to arrest in G2 phase, whereas Tet was able to lower the number of cells arrested in G2 phase. However, in MCF-7 cells, the potentiation effect of Tet was lower, and its SER was 1.10. MCF-7 cells were induced to arrest in G1 and G2 phases by X-rays, and the number of cells arrested in G2 phase abrogated by Tet was less than that in MCF-7/ADR cells. Furthermore, the results showed that the levels of Cyclin B1 and Cdc2 expression decreased after X-irradiation, and the mitotic index was lower too. Tet could reverse this decrease and induce X-ray-irradiated cells to enter mitosis. Conclusion: Tet is a potent G2 checkpoint abrogator and markedly enhances the cytotoxicity of X irradiation in the p53-mutant cancer cells

  14. HPV-positive HNSCC cell lines but not primary human fibroblasts are radiosensitized by the inhibition of Chk1

    International Nuclear Information System (INIS)

    Purpose: Despite the comparably high cure rates observed for HPV-positive HNSCC, there is still a great need for specific tumor radiosensitization due to the often severe side effects resulting from intense radiochemotherapy. We recently demonstrated that HPV-positive HNSCC cell lines are characterized by a defect in DNA double-strand break repair associated with a pronounced G2-arrest. Here we tested whether abrogation of this radiation-induced G2-arrest by the inhibition of Chk1 results in specific radiosensitization of HPV-positive HNSCC cells. Materials and methods: Experiments were performed with five HPV and p16-positive (93-VU-147T, UM-SCC-47, UT-SCC-45, UD-SCC-2, UPCI-SCC-154) and two HPV and p16-negative HNSCC cell lines, as well as two normal human fibroblast strains. Chk1 was inhibited by the selective inhibitor PF-00477736. Cell cycle distribution was determined by flow cytometry, Chk1-activity via Western blot and cell survival by colony formation assay. Results: With the exception of UPCI-SCC-154, the inhibition of Chk1 was found to abolish the pronounced radiation-induced G2-arrest in all HPV-positive cells utilized. All tumor cell lines that demonstrated the abrogation of G2-arrest also demonstrated radiosensitization. Notably, in G1-arrest-proficient normal human fibroblasts no radiosensitization was induced. Conclusion: Abrogation of the G2 checkpoint through the inhibition of Chk1 may be used to selectively increase the cellular radiosensitivity of HPV-positive HNSCC without affecting the surrounding normal tissue

  15. Axin gene methylation status correlates with radiosensitivity of lung cancer cells

    International Nuclear Information System (INIS)

    We previously reported that Axin1 (Axin) is down-regulated in many cases of lung cancer, and X-ray irradiation increased Axin expression and inhibited lung cancer cells. The mechanisms, however, were not clear. Four lung cancer cell lines were used to detect the methylation status of Axin with or without X-ray treatment. Real-time PCR was used to quantify the expression of Axin, and western blot analysis was applied to measure protein levels of Axin, β-catenin, Cyclin D1, MMP-7, DNMTS, MeCP2 and acetylated histones. Flow cytometric analysis, colony formation assay, transwell assay and xenograft growth experiment were used to study the biological behavior of the cells with hypermethylated or unmethylated Axin gene after X-ray treatment. Hypermethylated Axin gene was detected in 2 of 4 cell lines, and it correlated inversely with Axin expression. X-ray treatment significantly up-regulated Axin expression in H446 and H157 cells, which possess intrinsic hypermethylation of the Axin gene (P<0.01), but did not show up-regulation in LTE and H460 cells, which have unmethylated Axin gene. 2Gy X-ray significantly reduced colony formation (from 71% to 10.5%) in H157 cells, while the reduction was lower in LTE cells (from 71% to 20%). After X-ray irradiation, xenograft growth was significantly decreased in H157 cells (from 1.15 g to 0.28 g) in comparison with LTE cells (from 1.06 g to 0.65 g). Significantly decreased cell invasiveness and increased apoptosis were also observed in H157 cells treated with X-ray irradiation (P<0.01). Down-regulation of DNMTs and MeCP2 and up-regulation of acetylated histones could be detected in lung cancer cells. X-ray-induced inhibition of lung cancer cells may be mediated by enhanced expression of Axin via genomic DNA demethylation and histone acetylation. Lung cancer cells with a different methylation status of the Axin gene showed different radiosensitivity, suggesting that the methylation status of the Axin gene may be one important factor

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

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    Sandeep R Bhave

    2013-09-01

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

  17. Radiosensitivity evaluation of human tumor cell lines by detecting 4977 bp deletion in mitochondrial DNA and comet assay

    International Nuclear Information System (INIS)

    Objective: To explore the feasibility of determining radiosensitivity of human tumor cell lines in vitro using the assay of mtDNA 4977 bp deletion and comet assay. Methods: Three human tumor cell lines were selected in this study, HepG2, EC-9706 and MCF-7. The surviving fraction(SF), the ratio of mtDNA 4977 bp deletion and DNA damage were detected by MTY assay, nested PCR technique and comet assay, respectively. Results: The results of MTT assay showed that the radiosensitivity of HepG2 and EC-9706 was higher than that of MCF-7. The ratio of mtDNA 4977 bp deletion of HepG2 and EC-9706 was higher significantly than that of MCF-7 (P2 and EC-9706 was higher than that of MCF-7. The difference of radiosensitivity among these three tumor cell lines was significant after 8 Gy γ-ray irradiation. Conclusions: Combination of many biological parameter is helpful to evaluate the radiosensitivity of tumor cells more accurately. (authors)

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

    Science.gov (United States)

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

    2016-09-01

    Dimethoxycurcumin (DIMC), a structural analogue of curcumin, has been shown to have more stability, bioavailability, and effectiveness than its parent molecule curcumin. In this paper the radiosensitizing effect of DIMC has been investigated in A549 lung cancer cells. As compared to its parent molecule curcumin, DIMC showed a very potent radiosensitizing effect as seen by clonogenic survival assay. DIMC in combination with radiation significantly increased the apoptosis and mitotic death in A549 cells. This combinatorial treatment also lead to effective elimination of cancer stem cells. Further, there was a significant increase in cellular ROS, decrease in GSH to GSSG ratio and also significant slowdown in DNA repair when DIMC was combined with radiation. In silico docking studies and in vitro studies showed inhibition of thioredoxin reductase enzyme by DIMC. Overexpression of thioredoxin lead to the abrogation of radiosensitizing effect of DIMC underscoring the role of thioredoxin reductase in radiosensitization. Our results clearly demonstrate that DIMC can synergistically enhance the cancer cell killing when combined with radiation by targeting thioredoxin system. PMID:27381867

  19. Radiosensitization of Chinese hamster cells by pimonidazole (Ro 03-8799) at low x-ray doses

    International Nuclear Information System (INIS)

    The authors report on the radiosensitization of hypoxic Chinese hamster cells by pimonidazole (Ro 03-8799) which has undergone evaluation in clinical trials. The study also includes data obtained concurrently with misonidazole for comparative purposes. The survival data were fitted to the linear quadratic model: 1n S = -(αD + βD2 and estimates of α and β derived. (author)

  20. Modulation in the radiosensitivity of MCF-7 human breast carcinoma cells by 17B-estradiol and tamoxifen

    International Nuclear Information System (INIS)

    Colony-forming ability after irradiation was compared for proliferating hormone response MCF-7 breast carcinoma cells and cells whose growth was inhibited by tamoxifen or 17B-estradiol. Compared with controls (D0=1.20 Gy, n=3.1), cells in 1 μM or 5 μM tamoxifen were less radiosensitive (D0=1.20 Gy, n=70; D0=1.22 Gy, n=7.0, respectively), the predominant effect being a widened shoulder on the survival curve, which could be abolished by co-incubation of 5 μM tamoxifen with 100 nM or 5 μM 17B-estradiol (D0=1.30 Gy, n=2.6; D0=1.20 Gy, n=2.6, respectively). The decrease in radiosensitivity was similar to that seen when replating of irradiated plateau-phase cultures was delayed for 24 h (D0=1.30 Gy, n=6.0). When proliferation of MCF-7 cultures was inhibited by 10 μM 17B-estradiol, radiosensitivity was increased with a markedly diminished survival curve shoulder (D0=1.40 Gy, n=1.0). Different hormonal manipulations of cycling human breast carcinoma cells may have profound but disparate effects on radiosensitivity such that tamoxifen and estrogens may serve as useful agents with which to study the biochemical mechanisms of repair. (author)

  1. Radiosensitizing effect of gold nanoparticles in carbon ion irradiation of human cervical cancer cells

    International Nuclear Information System (INIS)

    Noble metal nanoparticles have received considerable attention in biotechnology for their role in bio sensing due to surface plasmon resonance, medical diagnostics due to better imaging contrast and therapy. The radiosensitization effect of gold nanoparticles (AuNP) has been gaining popularity in radiation therapy of cancer cells. The better depth dose profile of energetic ion beam proves its superiority over gamma radiation for fighting against cancer. In the present work, the glucose capped gold nanoparticles (Glu-AuNP) were synthesised and internalized in the HeLa cells. Transmission electron microscopic analysis of ultrathin sections of Glu-AuNP treated HeLa cells confirmed the internalization of Glu-AuNPs. Control HeLa cells and Glu-AuNp treated HeLa cells were irradiated at different doses of 62 MeV 12C ion beam (LET – 290keV/μm) at BIO beam line of using 15UD Pelletron accelerator at Inter University Accelerator Centre, New Delhi, India. The survival fraction was assessed by colony forming assay which revealed that the dose of carbon ion for 90% cell killing in Glu-AuNP treated HeLa cells and control HeLa cells are 2.3 and 3.2 Gy respectively. This observation shows ∼ 28% reduction of 12C6+ ion dose for Glu-AuNP treated HeLa cells as compared to control HeLa cells

  2. Effects of osteopontin inhibition on radiosensitivity of MDA-MB-231 breast cancer cells

    International Nuclear Information System (INIS)

    Osteopontin (OPN) is a secreted glycophosphoprotein that is overexpressed in various tumors, and high levels of OPN have been associated with poor prognosis of cancer patients. In patients with head and neck cancer, high OPN plasma levels have been associated with poor prognosis following radiotherapy. Since little is known about the relationship between OPN expression and radiosensitivity, we investigated the cellular and radiation induced effects of OPN siRNA in human MDA-MB-231 breast cancer cells. MDA-MB-231 cells were transfected with OPN-specific siRNAs and irradiated after 24 h. To verify the OPN knockdown, we measured the OPN mRNA and protein levels using qRT-PCR and Western blot analysis. Furthermore, the functional effects of OPN siRNAs were studied by assays to assess clonogenic survival, migration and induction of apoptosis. Treatment of MDA-MB-231 cells with OPN siRNAs resulted in an 80% decrease in the OPN mRNA level and in a decrease in extracellular OPN protein level. Transfection reduced clonogenic survival to 42% (p = 0.008), decreased the migration rate to 60% (p = 0.15) and increased apoptosis from 0.3% to 1.7% (p = 0.04). Combination of OPN siRNA and irradiation at 2 Gy resulted in a further reduction of clonogenic survival to 27% (p < 0.001), decreased the migration rate to 40% (p = 0.03) and increased apoptosis to 4% (p < 0.005). Furthermore, OPN knockdown caused a weak radiosensitization with an enhancement factor of 1.5 at 6 Gy (p = 0.09) and a dose modifying factor (DMF10) of 1.1. Our results suggest that an OPN knockdown improves radiobiological effects in MDA-MB-231 cells. Therefore, OPN seems to be an attractive target to improve the effectiveness of radiotherapy

  3. Antigen-primed helper T cell function in CBA/N mice is radiosensitive

    International Nuclear Information System (INIS)

    CBA/N mice have an X-linked immunodeficiency that includes a deficient humoral response to sheep red blood cells (SRBC). In order to study the cellular mechanisms of this deficiency we have examined helper T cell function to SRBC in an adoptive transfer system by using 2 different sources of helper T cells. When thymocytes were used as the source of helper T cell precursors in an adoptive transfer system, CBA/N thymocytes were as effective as CBA/Ca thymocytes in inducing CBA/Ca bone marrow cells to develop into both direct and indirect anti-SRBC plaque-forming cells (PFC). However, when SRBC-primed, irradiated recipient mice were used as the source of helper T cells, primed and irradiated CBA/N recipiets developed significantly fewer direct and indirect anti-SRBC PFC than similarly treated CBA/CA recipients when reconstituted with CBA/Ca bone marrow cells and challenged with SRBC. We conclude that antigen-primed helper T cell function in CBA/N mice is radiosensitive. Possible reasons for this are evaluated and discussed

  4. Chemosensitization and radiosensitization of a lung cancer cell line A549 induced by a composite polymer micelle.

    Science.gov (United States)

    Xu, Jing; Zhang, Bi-Cheng; Li, Xiang-Long; Xu, Wen-Hong; Zhou, Juan; Shen, Li; Wei, Qi-Chun

    2016-08-01

    Multidrug resistance (MDR) to Doxorubicin (DOX) remains a major obstacle to successful cancer treatment. The present study sought to overcome the MDR of lung cancer cells and achieve radiosensitization by developing a composite DOX-loaded micelle (M-DOX). M-DOX containing PEG-PCL/Pluronic P105 was prepared by the solvent evaporation method. Lung cancer cell line A549 was adopted in this study. In vitro cytotoxicity, cellular uptake behavior, subcellular distribution, and radiosensitivity were evaluated by the treatment with M-DOX, and free DOX was used as a control. A549 cells treated with M-DOX as opposed to free DOX showed greater cellular uptake as well as greater cytotoxicity. Furthermore, M-DOX reached the mitochondria and lysosome effectively after cellular uptake, and fluorescence used to track M-DOX was found to be surrounding the nucleus. Finally, colony-forming assays demonstrated that M-DOX treatment improved radiosensitization when compared to free DOX. Based on the increased cytotoxicity and radiosensitization, M-DOX could be considered as a promising drug delivery system to overcome MDR in lung cancer therapy. PMID:27585226

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

    International Nuclear Information System (INIS)

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

  6. N-acetylphytosphingosine enhances the radiosensitivity of tumor cells by increasing apoptosis

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    Han, Y.; Kim, Y.; Yun, Y.; Jeon, S.; Kim, K.; Song, J. [Lab. of Immunology, Korea Inst. of Radiological and Medical Sciences, KAERI, Seoul (Korea); Hong, S.H. [Lab. of Experimental therapeutics, Korea Inst. of Radiological and Medical Sciences, KAERI, Seoul (Korea); Park, C. [Doosan Biotech BU, Yongin-City, Kyonggi-Do (Korea)

    2005-07-01

    Ceramides are well-known second messengers which mediate apoptosis, proliferation, differentiation in mammalian cells, but the physiological roles of phytosphingosines are poorly understood. We hypothesized that one of the phytosphingosine derivatives, N-acetylphytosphingosine (NAPS) can induce apoptosis in human leukemia Jurkat cell line and increase apoptosis in irradiated MDA-MB-231 cells. We first examined the effect of NAPS on apoptosis of Jurkat cells. NAPS had a more rapid and stronger apoptotic effect than C{sub 2}-ceramide in Jurkat cells and significant increase of apoptosis was observed at 3 h after treatment. In contrast, the apoptosis induced by C2-ceramide was observed only after 16 h of treatment. NAPS induced apoptosis was mediated by caspase 3 and 8 activation and inhibited by z-VAD-fmk. Ceramide plays a pivotal role in radiation induced apoptosis. We postulated that exogenous treatment of NAPS sensitizes tumor cells to ionizing radiation, since NAPS might be used as a more effective alternative to C2-ceramide. As expected, NAPS decreased clonogenic survival of irradiated MDA-MB-231 cells dose dependently, and apoptosis of irradiated cells in the presence of NAPS was increased through the caspase activation. Taken together, NAPS is an effective apoptosis-inducing agent, which can be readily synthesized from yeast sources, and is a potent alternative to ceramide for the further study of ceramide associated signaling and the development of radiosensitizing agent. (orig.)

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

    International Nuclear Information System (INIS)

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

  8. Knock-down of miR-221 and miR-222 in the radiosensitization of breast cancer cells

    International Nuclear Information System (INIS)

    Objective: To investigate the radiosensitizing effect of knock-down of miR-221 miR-222 on MCF-7 human breast cancer cells and explore the possible mechanism. Methods: Antisense oligonucleotides of miR-221 and miR-222 (AS-miR-221 and AS-miR-222), mediated by lipofectamine, were transfected to MCF-7 cells to knock down miR-221 and miR-222, Northern blotting was conducted to detect the expression of miR-221 and miR-222 in transfected cells. The cell apoptosis was detected by flow cytometry and Caspase-3 and Caspase-7 activity assay. Clonogenic assay was used to measure the sensitizing enhancement ratio. Target genes of miR-221 and miR-222 relevant to radio-sensitivity were searched using bioinformatics analysis. The targeted protein expression was determined by Western blot analysis. Results: The expression of miR-221 and miR-222 in the AS-miR-221/222 cells determined by Northern blotting was significantly reduced. Compared with the control group, the cell apoptosis and mitotic cell death after the radiation were significantly higher in AS-miR-221/222 cells. The sensitizing enhancement ratio was 1.87. Based on bioinformatics analysis, PTEN was a target gene of miR-221 and miR-222 which could enhance the radiosensitivity of MCF-7 cells. In AS-miR-221/222 cells, the expression of PTEN was up-regulated while pAkt down-regulated. Conclusions: AS-miR-221 and AS-miR-222 may enhance the radiosensitivity of MCF-7 breast cancer cells by up-regulating the expression of PTEN. (authors)

  9. The temporal organization of processes of cell reproduction and its connection with rhythms of radiosensitivity of the body

    Science.gov (United States)

    Druzhinin, Y. P.; Romanov, Y. A.; Vatsek, A.

    1974-01-01

    Radiosensitivity of individual phases of the mitotic cycle was studied in synchronous cell cultures and in several biological objects. It was found that radiosensitivity changed essentially according to phases of the mitotic cycle, depending on the kind of cells, evaluation criteria and the radiation dosage. Tests on partially synchronized HeLa cell populations, according to the criterion of survival, showed them most sensitive during mitosis, as well as in later G sub 1- or early DNA-synthesizing stages. With radiation in doses of 300 rad, the proportion of surviving cells showed a sensitivity directly before DNA synthesis of approximately 4 times higher than the later S-phase and during the major portion of G sub 1- and G sub 2-periods. Sensitivity of cells in mitosis was approximately 3 times higher than in late G sub 1- and early S-phases.

  10. C646, a selective small molecule inhibitor of histone acetyltransferase p300, radiosensitizes lung cancer cells by enhancing mitotic catastrophe

    International Nuclear Information System (INIS)

    Background and purpose: Chromatin remodeling through histone modifications, including acetylation, plays an important role in the appropriate response to DNA damage induced by ionizing radiation (IR). Here we investigated the radiosensitizing effect of C646, a selective small molecule inhibitor of p300 histone acetyltransferase, and explored the underlying mechanisms. Materials and methods: A549, H157 and H460 human non-small cell lung carcinoma (NSCLC) cells, and HFL-III human lung fibroblasts were assessed by clonogenic survival assay. Apoptosis and necrosis were assessed by annexin V staining. Senescence was assessed by Senescence-associated β-galactosidase staining. Mitotic catastrophe was assessed by evaluating nuclear morphology with DAPI staining. Cell cycle profiles were analyzed by flow cytometry. Protein expression was analyzed by immunoblotting. Results: C646 sensitized A549, H460 and H157 cells to IR with a dose enhancement ratio at 10% surviving fraction of 1.4, 1.2 and 1.2, respectively. C646 did not radiosensitize HFL-III cells. In A549 cells, but not in HFL-III cells, C646 (i) enhanced mitotic catastrophe but not apoptosis, necrosis, or senescence after IR; (ii) increased the hyperploid cell population after IR; and (iii) suppressed the phosphorylation of CHK1 after IR. Conclusions: C646 radiosensitizes NSCLC cells by enhancing mitotic catastrophe through the abrogation of G2 checkpoint maintenance

  11. Radiosensitivity of mouse seminal vesicle cells which show proliferative response to androgen and estrogen

    International Nuclear Information System (INIS)

    Injections of either androgen or estrogen have been shown to induce proliferation of epithelial cells in the seminal vesicle of castrated mice. Uptake of 5-[125I]iodo-2'-deoxyuridine ([125I]IdUrd) by the whole seminal vesicle was used as an index for cell proliferation. Although uptake of [125I]IdUrd induced by androgen was about four times as great as that induced by estrogen, both values decreased with a similar pattern after irradiation. Uptake of [125I]IdUrd showed a dose-dependent decrease up to 1000 rad; the values remained unchanged until 4000 rad. Uptake of [125I]IdUrd by the radiosensitive cell population was calculated by substracting [I-125]IdUrd uptake attributable to the radioresistant cell population from total [I-125]IdUrd uptake. Androgen- and estrogen-responsive cells were equally sensitive to irradiation. Recovery of androgen-responsive cells from radiation-induced decrease was examined with or without androgen stimulation. Although recovery occurred without androgen, it was significantly enhanced by androgen stimulation following irradiation. Irradiation seems useful for investigation of kinetic characteristics of epithelial stem cells in the seminal vesicle of mice

  12. In vivo Radiosensitization Effect of HDAC Inhibitor, SK-7041 on RIF-1 Cell Line

    International Nuclear Information System (INIS)

    To test the radiosensitizing effect of the newly synthesized novel histone deacetylase inhibitor, SK-7041 in vivo. The RIF-1 cell line was implanted into the back of a 6-week-old female C3H mouse, intradermally. The mice were grouped into control, drug, radiation (RT), and RT+drug group. SK-7041, 4 mg/kg was administered intraperitoneally for six cycles every 12 hours for mice in the drug and RT+drug group. An identical volume of phosphate buffered saline (PBS) was administered at the same frequency to mice in the control and RT groups. A single 5 Gy fraction was delivered to mice in RT and RT+drug group 6 hours after the fourth delivery. The volume of the implanted tumor was measured every 2-3 days to formulate the growth delay curve. For the control, drug, RT, and RT+drug groups, the average duration for implanted tumor to reach a volume of 1,500 mm3 was 10 days, 10 days, 9 days, and 12 days, respectively. Moreover, the tumor volume on D14 was 276.7 mm3, 279.9 mm3, 292.5 mm3, and 185.5 mm3, respectively (p=0.0004). The difference for the change in slope for the control and drug versus the RT and RT+drug groups were borderline significant (p=0.0650). The results of this study indicate that SK-7041 has a radiosensitizing effect for the RIF-I cell line in vivo at a low concentration and this effect may be synergistic. Implementing this result to clinical trial is warranted.

  13. Individual radiosensitivity, its mechanisms and manifestations

    International Nuclear Information System (INIS)

    Considerable differences exist in radiosensitivity between individuals of the same species. Radiation damage to the organism may be influenced by the immediate state of its physiological functions. A survey is given of the radiosensitivity of cells, cell systems and their role in radiation damage of the organism. Other factors influencing the radiosensitivity of the organism are metabolic processes, biological rhythms and the age of the individual. Radiosensitivity is polyfactorially conditioned and is controlled either by genetic or by peristatic factors. (E.S.)

  14. antiEGFR conjugated gold nanoparticles for increasing radiosensitivity in lung cancer cells

    International Nuclear Information System (INIS)

    One of the set back that lies in lung cancer treatment is the over expression of Epidermal Growth Factor Receptor (EGFR). EGFR is a transmembrane receptor that is highly expressed in lung cancer that leads to cell survival, proliferation and spread of the disease. Over the years, EGFR inhibitors, monoclonal antibodies, are being used in combination with radiotherapy in lung cancer patients so as to achieve better results. In the recent time, application of Au nanoparticles (AuNPs) in diagnosis and treatment of cancer has been extensively used in biomedical research. Among various applications, there is considerable use of AuNPs seen on the dose enhancement effect (radiosensitization) in radiation therapy of cancer. The conjugation of AuNP with monoclonal antibody antiEGFR (antiEGFR-AuNP) may provide excellent agent to sensitize the cells to heavy ion radiation. We synthesized AuNPs by citrate reduction method. Most of AuNPs were in the size range of 6-8 nm as studies by Transmission Electron Microscope (TEM). These AuNPs were found to be non toxic in A549 cells and thus biocompatible. Further, we conjugated AuNPs with antiEGFR (antiEGFR-AuNP). The conjugation was confirmed by UV-Vis spectroscopy. A549 cells were treated with antiEGFR-AuNP. TEM was carried out of ultrathin cross sections of antiEGFR-AuNP treated A549 cells to check the attachment internalization of AuNPs. We observed that the AuNPs are attached on the cell membrane as well as internalized in cytoplasm. Upon exposure of antiEGFR-AuNP treated cells to heavy ion 12C beam, showed increase in radiosensitization as studied by survival assay and MTT assay. We will also explain the EGFR expression and cell cycle proliferation in A549 cells upon heavy ion beam irradiation of these. The study aims to overcome the current limitations of cancer-targeted therapies and improve the treatment modality of lung cancer. (author)

  15. Costunolide causes mitotic arrest and enhances radiosensitivity in human hepatocellular carcinoma cells

    Directory of Open Access Journals (Sweden)

    Chen Chih-Jen

    2011-05-01

    Full Text Available Abstract Purpose This work aimed to investigate the effect of costunolide, a sesquiterpene lactone isolated from Michelia compressa, on cell cycle distribution and radiosensitivity of human hepatocellular carcinoma (HCC cells. Methods The assessment used in this study included: cell viability assay, cell cycle analysis by DNA histogram, expression of phosphorylated histone H3 (Ser 10 by flow cytometer, mitotic index by Liu's stain and morphological observation, mitotic spindle alignment by immunofluorescence of alpha-tubulin, expression of cell cycle-related proteins by Western blotting, and radiation survival by clonogenic assay. Results Our results show that costunolide reduced the viability of HA22T/VGH cells. It caused a rapid G2/M arrest at 4 hours shown by DNA histogram. The increase in phosphorylated histone H3 (Ser 10-positive cells and mitotic index indicates costunolide-treated cells are arrested at mitosis, not G2, phase. Immunofluorescence of alpha-tubulin for spindle formation further demonstrated these cells are halted at metaphase. Costunolide up-regulated the expression of phosphorylated Chk2 (Thr 68, phosphorylated Cdc25c (Ser 216, phosphorylated Cdk1 (Tyr 15 and cyclin B1 in HA22T/VGH cells. At optimal condition causing mitotic arrest, costunolide sensitized HA22T/VGH HCC cells to ionizing radiation with sensitizer enhancement ratio up to 1.9. Conclusions Costunolide could reduce the viability and arrest cell cycling at mitosis in hepatoma cells. Logical exploration of this mitosis-arresting activity for cancer therapeutics shows costunolide enhanced the killing effect of radiotherapy against human HCC cells.

  16. The radiosensitivity of glioblastoma cell lines after hypoxia-induced Bax expression

    International Nuclear Information System (INIS)

    Full text: Radiation therapy is the most effective treatment after surgery for patients with malignant gliomas. However, the hypoxic cells exclusive to tumor tissue have proven resistant to both radiotherapy and many forms of chemotherapy. In order to specifically target these hypoxic cells, U-251 MG and U-87 MG human glioblastoma cells were stably transfected with constructs containing the suicide gene Bax under the regulation of nine copies of hypoxia-responsive elements (HREs). During hypoxia, the transcriptional complex hypoxia-inducible-factor 1 (HIF-1) binds to HRE and facilitates the transcription of downstream genes. Previously, hypoxia-induced Bax expression in transfected U-251 and U-87 clone cells has been shown to increase cell killing. The benefits of the gene therapy could be further expanded if Bax also acted to increase the sensitivity of these clone cells to radiation. To determine whether this was the case, parent and clone cells were irradiated with graded doses of X-rays under hypoxic conditions. These cells were then left hypoxic for varying durations of time, after which they were incubated for two weeks under aerated conditions to assay for clonogenic cell survival. After less than an hour under hypoxia, both U-251 and U-87 clone cells appeared significantly more sensitive to radiation than their respective parent cells. However, after longer amounts of time under anoxia, higher surviving fractions were found in each clone that were consistent with those of their respective parent cell line, showing that potentially lethal damage repair (PLDR) had occurred in the clone cells. Parent cells did not exhibit PLDR. Results are inconclusive at this point in time. Western blot analyses detailing the amount of Bax expression at each time point as well as further research exploring different durations of hypoxia will be necessary to reveal the nature of the correlation between Bax expression and radiosensitivity. Supported by NS-42927 and CA-85356

  17. Costunolide causes mitotic arrest and enhances radiosensitivity in human hepatocellular carcinoma cells

    International Nuclear Information System (INIS)

    This work aimed to investigate the effect of costunolide, a sesquiterpene lactone isolated from Michelia compressa, on cell cycle distribution and radiosensitivity of human hepatocellular carcinoma (HCC) cells. The assessment used in this study included: cell viability assay, cell cycle analysis by DNA histogram, expression of phosphorylated histone H3 (Ser 10) by flow cytometer, mitotic index by Liu's stain and morphological observation, mitotic spindle alignment by immunofluorescence of alpha-tubulin, expression of cell cycle-related proteins by Western blotting, and radiation survival by clonogenic assay. Our results show that costunolide reduced the viability of HA22T/VGH cells. It caused a rapid G2/M arrest at 4 hours shown by DNA histogram. The increase in phosphorylated histone H3 (Ser 10)-positive cells and mitotic index indicates costunolide-treated cells are arrested at mitosis, not G2, phase. Immunofluorescence of alpha-tubulin for spindle formation further demonstrated these cells are halted at metaphase. Costunolide up-regulated the expression of phosphorylated Chk2 (Thr 68), phosphorylated Cdc25c (Ser 216), phosphorylated Cdk1 (Tyr 15) and cyclin B1 in HA22T/VGH cells. At optimal condition causing mitotic arrest, costunolide sensitized HA22T/VGH HCC cells to ionizing radiation with sensitizer enhancement ratio up to 1.9. Costunolide could reduce the viability and arrest cell cycling at mitosis in hepatoma cells. Logical exploration of this mitosis-arresting activity for cancer therapeutics shows costunolide enhanced the killing effect of radiotherapy against human HCC cells

  18. Down-regulation of survivin expression by small interfering RNA induces pancreatic cancer cell apoptosis and enhances its radiosensitivity

    Institute of Scientific and Technical Information of China (English)

    Hai-Tao Guan; Xing-Huan Xue; Zhi-Jun Dai; Xi-Jing Wang; Ang Li; Zhao-Yin Qin

    2006-01-01

    AIM: To investigate the inhibitory effect of small interfering RNA (siRNA) on the expression of survivin in pancreatic cancer cell line PC-2 and the role of siRNA in inducing PC-2 cell apoptosis and enhancing its radiosensitivity.METHODS: A siRNA plasmid expression vector against survivin was constructed and transfected into PC-2 cells with LipofectamineTM 2000. The down regulation of survivin expression was detected by semi-quantitive RT-PCR and immunohistochemical SP method and the role of siRNA in inducing PC-2 cell apoptosis and enhancing its radiosensitivity was detected by flow cytometry.RESULTS: The sequence-specific siRNA efficiently and specifically down-regulated the expression of survivin at both mRNA and protein levels. The expression inhibition ratio was 81.25% at mRNA level detected by semiquantitive RT-PCR and 74.24% at protein level detected by immunohistochemical method. Forty-eight hours after transfection,apoptosis was induced in 7.03% cells by siRNA and in 14.58% cells by siRNA combined with radiation.CONCLUSION: The siRNA plasmid expression vector against survivin can inhibit the expression of survivin in PC-2 cells efficiently and specifically. Inhibiting the expression of survivin can induce apoptosis of PC-2 cells and enhance its radiosensitivity significantly. RNAi against survivin is of potential value in gene tnerapy of pancreatic cancer.

  19. Effects of introducing wild-type p53 gene on the radiosensitivity of SKOV-3 ovarian cancer cells

    International Nuclear Information System (INIS)

    Objective: To study the effect of wild-type p53 gene on the radiosensitivity of SKOV-3 ovarian cancer cells. Methods: Recombinant eukaryotic expression vector pcDNA3 containing full-length human wild-type p53 cDNA was introduced by lipofectamine-mediated gene transfection into cultured SKOV-3 cells which had been irradiated with 2 and 4 Gy X-rays, respectively. The radiosensitivities of the tumor cells with different p53 status were studied. Results: The number of colonies in the SKOV-3, SKOV-3-vect, and SKOV-3-p53 groups decreased by 18.6%, 22.9% and 44.5%, respectively with 2 Gy irradiation, and decreased by 63.6%, 64.9% and 88.9%, respectively with 4 Gy irradiation. After introduction of p53 cDNA, the cell number in S phase and the ratio of G2/M phase of tumor cells decreased and the ratio of G1/G0 phase increased. The introduction of p53 gene into cells led to cell cycle arrest in G1 phase. Conclusion: Exogenous introduction of wild-type p53 cDNA into SKOV-3 ovarian cancer cells can increase their radiosensitivity

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-04-15

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

  1. Genistein Enhances the Radiosensitivity of Breast Cancer Cells via G2/M Cell Cycle Arrest and Apoptosis

    Directory of Open Access Journals (Sweden)

    Li Gong

    2013-10-01

    Full Text Available The aim of the present study was to investigate the radiosensitizing effect of genistein, and the corresponding mechanisms of action on breast cancer cells with different estrogen receptor (ER status. Human breast cancer cell lines such as MCF-7 (ER-positive, harboring wild-type p53 and MDA-MB-231 (ER-negative, harboring mutant p53 were irradiated with X-rays in the presence or absence of genistein. Cell survival, DNA damage and repair, cell cycle distribution, cell apoptosis, expression of proteins related to G2/M cell cycle checkpoint and apoptosis were measured with colony formation assays, immunohistochemistry, flow cytometry and western blot analysis, respectively. Genistein showed relatively weak toxicity to both cell lines at concentrations in the range of 5–20 μM. Using the dosage of 10 μM genistein, the sensitizer enhancement ratios after exposure to X-rays at a 10% cell survival (IC10 were 1.43 for MCF-7 and 1.36 for MDA-MB-231 cells, respectively. Significantly increased DNA damages, arrested cells at G2/M phase, decreased homologous recombination repair protein Rad51 foci formation and enhanced apoptotic rates were observed in both cell lines treated by genistein combined with X-rays compared with the irradiation alone. The combined treatment obviously up-regulated the phosphorylation of ATM, Chk2, Cdc25c and Cdc2, leading to permanent G2/M phase arrest, and up-regulated Bax and p73, down-regulated Bcl-2, finally induced mitochondria-mediated apoptosis in both cell lines. These results suggest that genistein induces G2/M arrest by the activation of the ATM/Chk2/Cdc25C/Cdc2 checkpoint pathway and ultimately enhances the radiosensitivity of both ER+ and ER- breast cancer cells through a mitochondria-mediated apoptosis pathway.

  2. The alkylphospholipid, perifosine, radiosensitizes prostate cancer cells both in vitro and in vivo

    International Nuclear Information System (INIS)

    Perifosine is a membrane-targeted alkylphospholipid developed to inhibit the PI3K/Akt pathway and has been suggested as a favorable candidate for combined use with radiotherapy. In this study, we investigated the effect of the combined treatment of perifosine and radiation (CTPR) on prostate cancer cells in vitro and on prostate cancer xenografts in vivo. Human prostate cancer cell line, CWR22RV1, was treated with perifosine, radiation, or CTPR. Clonogenic survival assays, sulforhodamine B cytotoxity assays and cell density assays were used to assess the effectiveness of each therapy in vitro. Measurements of apoptosis, cell cycle analysis by flow cytometry and Western blots were used to evaluate mechanisms of action in vitro. Tumor growth delay assays were used to evaluate radiation induced tumor responses in vivo. In vitro, CTPR had greater inhibitory effects on prostate cancer cell viability and clonogenic survival than either perifosine or radiation treatment alone. A marked increase in prostate cancer cell apoptosis was noted in CTPR. Phosphorylation of AKT-T308 AKT and S473 were decreased when using perifosine treatment or CTPR. Cleaved caspase 3 was significantly increased in the CTPR group. In vivo, CTPR had greater inhibitory effects on the growth of xenografts when compared with perifosine or radiation treatment alone groups. Perifosine enhances prostate cancer radiosensitivity in vitro and in vivo. These data provide strong support for further development of this combination therapy in clinical studies

  3. Radiosensitizing effects of nitroimidazole nucleoside analogues on cultured mammalian cells at low radiation doses

    International Nuclear Information System (INIS)

    Radiosensitizing effects of nitroimidazole nucleoside analogues (RK-27, RK-28 and RK-29) were studied using cultured mouse leukemic L5178Y (L5178Y) cells and Chinese hamster V79 (CH V79) cells. There was no significant difference in sensitizer enhancement ratio among the three RK-compounds. The ratios were 1.7 for L5178Y cells and 1.6 for CH V79 cells at 1 mM concentration and were comparable to that of misonidazole. Sensitizer enhancement ratios of RK-28 for L5178Y cells irradiated with 1 to 4 Gy X-rays were, respectively, 1.5 to 1.6 at 0.5 mM concentration, which were nearly the same as those obtained at high doses. RK-28 was as effective for fractionated X-irradiation as for single X-irradiation, assuming complete repair of sublethal damage during incubation at 37degC between sessions of fractionated X-irradiation. The sensitizing effects of RK-28 were additive in combination with neocarzinostatin, an antitumor drug, which has different pharmacological and physiological properties, and enhances the radioresponse of cells. RK-28 is known to be rapidly metabolized and excreted in vivo and is thus expected to be less toxic than misonidazole. It was effective at low radiation doses routinely used in radiotherapy practice and for fractionated X-irradiation, suggesting its clinical utility. (author)

  4. Mitochondria-Targeted Analogues of Metformin Exhibit Enhanced Antiproliferative and Radiosensitizing Effects in Pancreatic Cancer Cells.

    Science.gov (United States)

    Cheng, Gang; Zielonka, Jacek; Ouari, Olivier; Lopez, Marcos; McAllister, Donna; Boyle, Kathleen; Barrios, Christy S; Weber, James J; Johnson, Bryon D; Hardy, Micael; Dwinell, Michael B; Kalyanaraman, Balaraman

    2016-07-01

    Metformin (Met) is an approved antidiabetic drug currently being explored for repurposing in cancer treatment based on recent evidence of its apparent chemopreventive properties. Met is weakly cationic and targets the mitochondria to induce cytotoxic effects in tumor cells, albeit not very effectively. We hypothesized that increasing its mitochondria-targeting potential by attaching a positively charged lipophilic substituent would enhance the antitumor activity of Met. In pursuit of this question, we synthesized a set of mitochondria-targeted Met analogues (Mito-Mets) with varying alkyl chain lengths containing a triphenylphosphonium cation (TPP(+)). In particular, the analogue Mito-Met10, synthesized by attaching TPP(+) to Met via a 10-carbon aliphatic side chain, was nearly 1,000 times more efficacious than Met at inhibiting cell proliferation in pancreatic ductal adenocarcinoma (PDAC). Notably, in PDAC cells, Mito-Met10 potently inhibited mitochondrial complex I, stimulating superoxide and AMPK activation, but had no effect in nontransformed control cells. Moreover, Mito-Met10 potently triggered G1 cell-cycle phase arrest in PDAC cells, enhanced their radiosensitivity, and more potently abrogated PDAC growth in preclinical mouse models, compared with Met. Collectively, our findings show how improving the mitochondrial targeting of Met enhances its anticancer activities, including aggressive cancers like PDAC in great need of more effective therapeutic options. Cancer Res; 76(13); 3904-15. ©2016 AACR. PMID:27216187

  5. Basal HIF-1a expression levels are not predictive for radiosensitivity of human cancer cell lines

    Energy Technology Data Exchange (ETDEWEB)

    Schilling, D.; Multhoff, G. [Klinikum rechts der Isar der Technischen Univ. Muenchen (Germany). Dept. of Radiation Oncology; Helmholtz Center Munich, CCG - Innate Immunity in Tumor Biology, Munich (Germany). German Research Center for Environmental Health - Inst. of Pathology; Bayer, C.; Emmerich, K.; Molls, M.; Vaupel, P. [Klinikum rechts der Isar der Technischen Univ. Muenchen (Germany). Dept. of Radiation Oncology; Huber, R.M. [Klinikum der Univ. Muenchen (Germany). Dept. of Pneumology

    2012-04-15

    High levels of hypoxia inducible factor (HIF)-1a in tumors are reported to be associated with tumor progression and resistance to therapy. To examine the impact of HIF-1a on radioresistance under normoxia, the sensitivity towards irradiation was measured in human tumor cell lines that differ significantly in their basal HIF-1a levels. HIF-1a levels were quantified in lysates of H1339, EPLC-272H, A549, SAS, XF354, FaDu, BHY, and CX- tumor cell lines by ELISA. Protein levels of HIF-1a, HIF-2a, carbonic anhydrase IX (CA IX), and GAPDH were assessed by Western blot analysis. Knock-down experiments were performed using HIF-1a siRNA. Clonogenic survival after irradiation was determined by the colony forming assay. According to their basal HIF-1a status, the tumor cell lines were divided into low (SAS, XF354, FaDu, A549, CX-), intermediate (EPLC-272H, BHY), and high (H1339) HIF-1a expressors. The functionality of the high basal HIF-1a expression in H1339 cells was proven by reduced CA IX expression after knocking-down HIF-1a. Linear regression analysis revealed no correlation between basal HIF-1a levels and the survival fraction at either 2 or 4 Gy in all tumor cell lines investigated. Our data suggest that basal HIF-1a levels in human tumor cell lines do not predict their radiosensitivity under normoxia. (orig.)

  6. Expression of the bifunctional suicide gene CDUPRT increases radiosensitization and bystander effect of 5-FC in prostate cancer cells

    International Nuclear Information System (INIS)

    Purpose: To test the hypothesis that, with 5-fluorocytosine (5-FC) treatment, the co-expression of cytosine deaminase (CD) and uracil phosphoribosyltransferase (UPRT) can lead to greater radiosensitization and bystander effect than CD-expression alone. Methods and materials: R3327-AT cell lines stably expressing CD or CDUPRT were generated. The 5-FC and 5-FU cytotoxicity, and the radiosensitivity with/without 5-FC treatment, of these cells were evaluated under both aerobic and hypoxic conditions. The bystander effect was assessed by apoptosis staining and clonogenic survival. The pharmacokinetics of 5-FU and 5-FC metabolism was monitored in mice bearing CD- or CDUPRT-expressing tumors using 19F MR spectroscopy (MRS). Results: CDUPRT-expressing cells were more sensitive to 5-FC and 5-FU than CD-expressing cells. CDUPRT-expression further enhanced the radiosensitizing effect of 5-FC, relative to that achieved by CD-expression alone. A 25-fold lower dose of 5-FC resulted in the same magnitude of radiosensitization in CDUPRT-expressing cells, relative to that in CD-expressing cells. The 5-FC cytotoxicity in co-cultures of parental cells mixed with 10-20% CDUPRT cells was similar to that in 100% CDUPRT cells. 19F MRS measurements showed that expression of CDUPRT leads to enhanced accumulation of fluorine nucleotide (FNuc), relative to that associated with CD-expression alone. Conclusion: Our study suggests that CDUPRT/5-FC strategy may be more effective than CD/5-FC, especially when used in combination with radiation.

  7. A correlation between DNA-nuclear matrix binding and relative radiosensitivity in two human squamous cell carcinoma cell lines

    International Nuclear Information System (INIS)

    Three aspects of DNA topology were examined in two human squamous cell carcinoma lines of differing radiosensitivity (SQ-9G, D0 = 1.46 Gy; and SQ-20B, D0 = 2.36 Gy). High-salt-extracted nuclei (nucleoids) were taken from γ-irradiated cells, stained with ethidium bromide and examined by flow cytometry. After 5 Gy, nucleoids from SQ-9G cells became 30% less efficient at adopting positive DNA supercoils than were unirradiated controls. Only a 4% difference was found with the radioresistant SQ-20B line. Both lines produced positive supercoils more efficiently after irradiation if first exposed to the topoisomerase II inhibitor VP16. Ethidium bromide titration of nucleoids was consistent with each containing similar numbers and sizes of DNA loops. In each line approximately 30-35% of DNA was accessible to trioxsalen, shown by inter-strand crosslinking after UV photo-activation. Exhaustive digestion of nuclear DNA by DNase I removed more DNA from the radiosensitive than from the radioresistant cell line (12% vs 28% remaining), thought to be due to the increased accessibility of SQ-9G DNA in vitro. (author)

  8. VE-821, an ATR inhibitor, causes radiosensitization in human tumor cells irradiated with high LET radiation

    International Nuclear Information System (INIS)

    High linear energy transfer (LET) radiation such as carbon ion particles is successfully used for treatment of solid tumors. The reason why high LET radiation accomplishes greater tumor-killing than X-rays is still not completely understood. One factor would be the clustered or complex-type DNA damages. We previously reported that complex DNA double-strand breaks produced by high LET radiation enhanced DNA end resection, and this could lead to higher kinase activity of ATR protein recruited to RPA-coated single-stranded DNA. Although the effect of ATR inhibition on cells exposed to low LET gamma-rays has recently been reported, little is known regarding the effect of ATR inhibitor on cells treated with high LET radiation. The purpose of this study is to investigate the effects of the ATR inhibitor VE-821 in human tumor and normal cells irradiated with high LET carbon ions. HeLa, U2OS, and 1BR-hTERT (normal) cells were pre-treated with 1 μM VE-821 for 1 hour and irradiated with either high LET carbon ions or X-rays. Cell survival, cell cycle distribution, cell growth, and micronuclei formation were evaluated. VE-821 caused abrogation of G2/M checkpoint and forced irradiated cells to divide into daughter cells. We also found that carbon ions caused a higher number of multiple micronuclei than X-rays, leading to decreased cell survival in tumor cells when treated with VE-821, while the survival of irradiated normal cells were not significantly affected by this inhibitor. ATR inhibitor would be an effective tumor radiosensitizer with carbon ion irradiation. The online version of this article (doi:10.1186/s13014-015-0464-y) contains supplementary material, which is available to authorized users

  9. Prediction of human cell radiosensitivity: Comparison of clonogenic assay with chromosome aberrations scored using premature chromosome condensation with fluorescence in situ hybridization

    International Nuclear Information System (INIS)

    The purpose of the present investigation was to determine whether chromosome aberrations scored by premature chromosome condensation (PCC) and fluorescence in situ hybridization (FISH) can predict the radiosensitivity of human cell lines, thereby providing a possible means of assessing the in situ radiosensitivity of normal tissues and the radiocurability of individual human cancers. We used four cells lines of different radiosensitivity: normal human fibroblasts (AG1522), ataxia-telangiectasia fibroblasts (AT2052), a human fibrosarcoma cell line (HT1080), and a human melanoma cell line (melanoma 903). These were irradiated in plateau phase with a range of doses and assessed both for clonogenic cell survival and for aberrations in a single chromosome (number 4) immediately after, and 24 h after irradiation. The initial number of breaks in chromosome 4 was proportional to irradiation dose and was identical for all the different human cell lines, irrespective of radiosensitivity. On the other hand, the number of chromosome 4 breaks remaining 24 h after irradiation reflected the radiosensitivity of the cells such that the relationship between residual chromosome aberrations and cell survival was the same for the different cell lines. These results suggest that the scoring of chromosome aberrations in interphase using FISH with PCC holds considerable promise for predicting the radiosensitivity of normal and tumor tissues in situ. 28 refs., 4 figs

  10. Apoptosis and radiosensitivity induced by N-acety1 phytosphingosine, in human cancer cell line

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Y. H.; Kim, K. S.; Han, Y. S.; Jeon, S. J.; Song, J. Y.; Jung, I. S.; Hong, S. H.; Yun, Y. S. [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Park, J. S. [Doosan Biotech, Yongin (Korea, Republic of)

    2004-07-01

    Ceramide is a key lipid molecule in signal transduction with a role in various regulatory pathways including differentiation, proliferation and especially apoptosis. Ionizing radiation-induced apoptosis is associated with accumulation of ceramide, and the sphingomyelinase deficiency results in radioresistance. We investigated the exogenous treatment of N-acetyl-phytosphingosine (NAPS), an analogue of N-acetyl-sphingosine (C{sub 2}-Ceramide), and C{sub 2}-ceramide exert apoptotic effect on human T cell lymphoma Jurkat cells and breast cancer cell line MDA-MB-231. NAPS and C{sub 2}-Ceramide has cytotoxic effect in time- and dose-dependent manner, and increased caspase-3, 8 activity. However, NAPS induced apoptosis more effectively, and increased caspase activity induced by NAPS is more higher than C{sub 2}-ceramide. Moreover, NAPS decreased clonogenicity of irradiated cells and increased radiation-induced apoptosis significantly. Increased cell death by irradiation in the presence of NAPS is owing to the increase of caspase activity. These data suggest that NAPS might be used for lead as a new type of radiosensitizing agent increasing radiation-induced apoptosis.

  11. p53 levels, cell cycle kinetics and radiosensitivity in two SV40 transformed Wi38VA13 fibroblast strains

    International Nuclear Information System (INIS)

    Background: The tumor suppressor protein p53 which can mediate an ionizing radiation-induced G1 arrest in mammalian cells, forms complexes with SV40 large T antigen (l-T-Ag). We have analyzed the p53 levels, the capability to undergo a G1 arrest and the radiosensitivity of two SV40 transformed fibroblast strains differing in their large T antigen expression. Material and Methods: One of the two strains (VA13F) is the commercially available form of Wi38VA13, the other (VA13E) arose spontaneously from the original one in our laboratory. Their p53 levels were measured by means of flow cytometry (FCM) and Western blot (WB) with two p53 antibodies (Ab-3, clone PAb240; Ab-6, clone DO-1; both Oncogene Science). Cell cycle distributions were determined flow cytometrically after BrdU labeling at regular time intervals after exposure to 250 kV X-rays. Radiosensitivity was assessed in a clonogenicity assay. Results: The p53 levels of the two strains corresponded to their large T antigen expression, presumably due to complex formation between the two proteins. The strain with a high p53 level did not show a G1 arrest and had a relatively high radiosensitivity, whereas the strain with a low p53 level showed a significant G1 arrest and a lower radiosensitivity. Conclusion: These results suggest that 1. complex formation between the large T antigen and p53 reduces the latter's functionality; 2. in these two strains the G1 arrest is one of the factors determining radiosensitivity. (orig.)

  12. High radiosensitivity of induction in contrast to radioresistance of expression of cells mediating delayed-type hypersensitivity during response to sheep red blood cells in mice

    International Nuclear Information System (INIS)

    The delayed-type hypersensitivity (DTH) reaction observed in mice primed i.v. with low doses of sheep red blood cells was greatly decreased when mice were irradiated with 300 rad before priming. An estimation of the radiosensitivity of DTH-mediating cells (DTH-C) was performed using a titration assay after local adoptive transfer of these cells mixed with antigen into the footpad of unprimed mice. A high radiosensitivity of the induction of DTH-C was observed with a D37 of approximately 50 rad. In contrast, the expression of DTH-C appeared radioresistant, as the D37 was approximately 2000 rad. (author)

  13. 3D cell cultures of human head and neck squamous cell carcinoma cells are radiosensitized by the focal adhesion kinase inhibitor TAE226

    International Nuclear Information System (INIS)

    Background and purpose: Focal adhesion kinase (FAK), a main player in integrin signaling and survival, is frequently overexpressed in human cancers and therefore postulated as potential target in cancer therapy. The aim of this study was to evaluate the radiosensitizing potential of the FAK inhibitor TAE226 in three-dimensional (3D) tumor cell cultures. Materials and methods: Head and neck squamous cell carcinoma (HNSCC) cells (FaDu, UT-SCC15, UT-SCC45), lung cancer cells (A549), colorectal carcinoma cells (DLD-1, HCT-116) and pancreatic tumor cells (MiaPaCa2, Panc1) were treated with different concentrations of TAE226 (0-1 μm; 1 or 24 h) without or in combination with irradiation (0-6 Gy, X-ray, single dose). Subsequently, 3D clonogenic survival assays (laminin-rich extracellular matrix) and Western blotting (expression/phosphorylation, e.g. FAK, Akt, ERK1/2) were performed. Results: All investigated 3D cell cultures showed a dose-dependent reduction in clonogenic survival by TAE226. Intriguingly, TAE226 only significantly radiosensitized 3D HNSCC cell cultures accompanied by a pronounced dephosphorylation of FAK, Akt and ERK1/2. Conclusions: Our data demonstrate TAE226 as potent FAK inhibitor that enhances the cellular radiosensitivity particularly of HNSCC cells grown in a 3D cell culture model. Future in vitro and in vivo investigations will clarify, to which extent this approach might be clinically relevant for radiotherapy of HNSCC.

  14. Cytotoxic and radiosensitizing effects of nano-C{sub 60} on tumor cells in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Ni Jin [Second Military Medical University, Department of Radiation Medicine (China); Wu Qiuye [Second Military Medical University, Organic Chemistry Department, School of Pharmacy (China); Li Yuguo [Chinese Academy of Sciences, Lab of Nanoscale Biomedicine Shanghai Institute of Applied Physics (China); Guo Zhixin [Chinese Academy of Sciences, Institute of Chemistry (China); Tang Gusheng; Sun Ding; Gao Fu; Cai Jianming [Second Military Medical University, Department of Radiation Medicine (China)], E-mail: caijm@smmu.edu.cn

    2008-04-15

    There is growing evidence in recent years that the pristine fullerene may be endowed with strong pro-oxidant capacity to biological samples. In this investigation we tested the hypothesis that water-soluble fullerene-C{sub 60} (nano-C{sub 60}) may interact with ionizing radiation enhancing its antiproliferative effects. The two tumor cell lines with different radiosensitivity B16 and SMMU-7721 were treated by a combination of pristine fullerene and {sup 60}Co {gamma} irradiation. We measured cell survival rates, apoptotic characteristics, reactive oxygen species (ROS) production and alteration of cell diameter with or without {gamma}-irradiation. There was reduced survival with B16 and SMMU-7721 cells exposed to nano-C{sub 60}, with the inhibitory concentrations reducing the viability by 50% to 65 part per billion (ppb) and 150 ppb respectively. For cells exposed to nano-C{sub 60} prior to {gamma}-irradiation, damage to cell membranes and increased numbers of apoptotic cells were detected by morphologic Hoechst-staining analysis and Annexin V/propidium iodide double-staining. In cells exposed to nano-C{sub 60}, there were increased levels of ROS, as measured by fluorescence detection under laser confocal microscopy. Preincubation with non-toxic pristine C{sub 60} before {gamma}-ray caused enlargement of cells with increased diameter. The results show that nano-C{sub 60} inhibits the growth of tumor cells at certain concentrations and increases the effects of {sup 60}Co {gamma}-irradiation, possibly through the elevated production of cellular ROS and the membrane disruption. Data in this study indicates a possible consideration of using C{sub 60} as a candidate of sensitization modifier in tumor radiation biology.

  15. miR-25 modulates NSCLC cell radio-sensitivity through directly inhibiting BTG2 expression

    International Nuclear Information System (INIS)

    A large proportion of the NSCLC patients were insensitive to radiotherapy, but the exact mechanism is still unclear. This study explored the role of miR-25 in regulating sensitivity of NSCLC cells to ionizing radiation (IR) and its downstream targets. Based on measurement in tumor samples from NSCLC patients, this study found that miR-25 expression is upregulated in both NSCLC and radio-resistant NSCLC patients compared the healthy and radio-sensitive controls. In addition, BTG expression was found negatively correlated with miR-25a expression in the both tissues and cells. By applying luciferase reporter assay, we verified two putative binding sites between miR-25 and BTG2. Therefore, BTG2 is a directly target of miR-25 in NSCLC cancer. By applying loss-and-gain function analysis in NSCLC cell lines, we demonstrated that miR-25-BTG2 axis could directly regulated BTG2 expression and affect radiotherapy sensitivity of NSCLC cells. - Highlights: • miR-25 is upregulated, while BTG2 is downregulated in radioresistant NSCLC patients. • miR-25 modulates sensitivity to radiation induced apoptosis. • miR-25 directly targets BTG2 and suppresses its expression. • miR-25 modulates sensitivity to radiotherapy through inhibiting BTG2 expression

  16. Enhancement of cetuximab on radiosensitivity of colorectal cancer cells exposed to 125I seeds

    International Nuclear Information System (INIS)

    Objective: To investigate the effect of cetuximab (C225) on the radiosensitivity of colorectal cancer cells CL187 and underlying mechanism. Methods: Cell survival was detected by colony forming assay. The levels of apoptosis and cell cycle distribution were determined by flow cytometer. The mitotic ratio was measured by Wright's-Giemsa mixed coloring method. The protein levels of Bax and Bcl2 were detected by Western blot. Results: The sensitizing enhancement ratio of C225 was approximately 1.4. C225 treatment and 125I seed radiation induced G1 cell cycle arrest individually. C225 increased the radiation-induced apoptosis (t =6.6, P<0.05) and cellular Bax/Bcl-2 ratio (t =9.4, P<0.05), but did not increase radiation-induced G1 arrest. In addition, there was no difference in mitotic index among different groups. Conclusions: C225 sensitizes CL187 to 125I seed irradiation,which might be related with increase of radiation-induced apoptosis. (authors)

  17. miR-25 modulates NSCLC cell radio-sensitivity through directly inhibiting BTG2 expression

    Energy Technology Data Exchange (ETDEWEB)

    He, Zhiwei, E-mail: carlhe@126.com; Liu, Yi, E-mail: cassieliu@126.com; Xiao, Bing, E-mail: rockg714@aliyun.com; Qian, Xiaosen, E-mail: xiaosenqian@126.com

    2015-02-13

    A large proportion of the NSCLC patients were insensitive to radiotherapy, but the exact mechanism is still unclear. This study explored the role of miR-25 in regulating sensitivity of NSCLC cells to ionizing radiation (IR) and its downstream targets. Based on measurement in tumor samples from NSCLC patients, this study found that miR-25 expression is upregulated in both NSCLC and radio-resistant NSCLC patients compared the healthy and radio-sensitive controls. In addition, BTG expression was found negatively correlated with miR-25a expression in the both tissues and cells. By applying luciferase reporter assay, we verified two putative binding sites between miR-25 and BTG2. Therefore, BTG2 is a directly target of miR-25 in NSCLC cancer. By applying loss-and-gain function analysis in NSCLC cell lines, we demonstrated that miR-25-BTG2 axis could directly regulated BTG2 expression and affect radiotherapy sensitivity of NSCLC cells. - Highlights: • miR-25 is upregulated, while BTG2 is downregulated in radioresistant NSCLC patients. • miR-25 modulates sensitivity to radiation induced apoptosis. • miR-25 directly targets BTG2 and suppresses its expression. • miR-25 modulates sensitivity to radiotherapy through inhibiting BTG2 expression.

  18. Betulinyl Sulfamates as Anticancer Agents and Radiosensitizers in Human Breast Cancer Cells

    Directory of Open Access Journals (Sweden)

    Matthias Bache

    2015-11-01

    Full Text Available Betulinic acid (BA, a natural compound of birch bark, is cytotoxic for many tumors. Recently, a betulinyl sulfamate was described that inhibits carbonic anhydrases (CA, such as CAIX, an attractive target for tumor-selective therapy strategies in hypoxic cancer cells. Data on combined CAIX inhibition with radiotherapy are rare. In the human breast cancer cell lines MDA-MB231 and MCF7, the effects of BA and betulinyl sulfamates on cellular and radiobiological behavior under normoxia and hypoxia were evaluated. The two most effective betulinyl sulfamates CAI 1 and CAI 3 demonstrated a 1.8–2.8-fold higher cytotoxicity than BA under normoxia in breast cancer cells, with IC50 values between 11.1 and 18.1 µM. BA exhibits its strongest cytotoxicity with IC50 values of 8.2 and 16.4 µM under hypoxia. All three substances show a dose-dependent increase in apoptosis, inhibition of migration, and inhibition of hypoxia-induced gene expression. In combination with irradiation, betulinyl sulfamates act as radiosensitizers, with DMF10 values of 1.47 (CAI 1 and 1.75 (CAI 3 under hypoxia in MDA-MB231 cells. BA showed additive effects in combination with irradiation. Taken together; our results suggest that BA and betulinyl sulfamates seem to be attractive substances to combine with radiotherapy; particularly for hypoxic breast cancer.

  19. Knockdown of checkpoint kinase 1 is associated with the increased radiosensitivity of glioblastoma stem-like cells

    International Nuclear Information System (INIS)

    Glioblastoma multiforme is an aggressive brain tumor with a poor prognosis. The glioblastoma stem-like cells (GSCs) represent a rare fraction of human glioblastoma cells with the capacity for multi-lineage differentiation, self-renewal and exact recapitulation of the original tumor. Interestingly, GSCs are more radioresistant compared with other tumor cells. In addition, the remarkable radioresistance of GSCs has been known to promote radiotherapy failure and therefore is associated with a significantly higher risk of a local tumor recurrence. Moreover, the hyperactive cell cycle checkpoint kinase (Chk) 1 and 2 play a pivotal role in the DNA damage response including radiation and chemical therapy. Based on aforementioned, we hypothesized that knockdown of Chk1 or Chk2 might confer radiosensitivity on GSCs and thereby increases the efficiency of radiotherapy. In this study, we knocked down the expression of Chk1 or Chk2 in human GSCs using lentivirus-delivered short hairpin RNA (shRNA) to examine its effect on the radiosensitivity. After radiation, the apoptosis rate and the cell cycle of GSCs were measured with Flow Cytometry. Compared with control GSCs (apoptosis, 7.82±0.38%; G2/M arrest, 60.20±1.28%), Chk1 knockdown in GSCs increased the apoptosis rate (37.87±0.32%) and decreased the degree of the G2/M arrest (22.37±2.01%). In contrast, the radiosensitivity was not enhanced by Chk2 knockdown in GSCs. These results suggest that depletion of Chk1 may improve the radio-sensitivity of GSCs via inducing cell apoptosis. In summary, the therapy targeting Chk1 gene in the GSCs may be a novel way to treat glioblastoma. (author)

  20. Computer simulation of tumour control probabilities after irradiation for varying intrinsic radio-sensitivity using a single cell based model

    International Nuclear Information System (INIS)

    Background. Currently, optimisation of the dose distribution and clinical acceptance are almost entirely based on the physical dose distribution and tumour control probability modelling is far from being routinely used as objective in treatment planning. For future individualised radiotherapeutic strategies, a reliable patient specific simulation model, taking into account customised tumour features, is needed to predict and improve treatment outcome. Materials and methods. To approach these demands, a single cell and Monte-Carlo based model was developed, which enables three-dimensional tumour growth and radiation response simulation. Tumour cells were characterised by cell-associated features such as age, intrinsic radio-sensitivity, proliferation ability, and oxygenation status, while capillary cells were considered as sources of a radial-dependent oxygen profile. Response to radiation was simulated by the linear-quadratic model, taking into account the lower radio-sensitivity of poorly oxygenated tumour cells. Results. The present study shows the influence of the model components and demonstrates the impact of the intra- and inter-tumoural radio-sensitivity heterogeneity on the treatment response. Conclusion. The simulation model adequately delineates the importance of the above described selected parameters on tumour control probability, providing an insight into the interplay of different physical and biological parameters, and its relevance for an individual tumour response

  1. Polyfunctional radiosensitizers. III. Effect of the biradical (Ro-03-6061) in combination with other radiosensitizers on the survival of hypoxic V-79 cells

    International Nuclear Information System (INIS)

    The biradical Ro-03-6061 removes the shoulder from the survival curve of hypoxic V-79 whereas both NPPN and PNAP are dose-modifying sensitizers like oxygen. When hypoxic cells were irradiated in the presence of a combination of NPPN and the biradical at equivalent radical concentrations, the survival curve was similar to that for cells irradiated in the presence of NPPN alone. When a combination of PNAP and the biradical were used at a concentration where the number of electron affinic (PNAP) molecules was equal to the number of free radical moieties, the resultant D0 value was similar to that for PNAP alone, but the shoulder of the curve was not completely restored. In experiments where the biradical was used in combination with diamide the effect was additive. Cell kill was exponential even at low doses when 0.05 mM diamide was used in combination with 0.1 mM biradical; the extrapolation number was 1.0 and the D0 was 240 rad. The results suggest mechanistic differences between electron affinic, free radical, and sulfhydryl-binding radiosensitizers, and also differences between monofunctional and polyfunctional sensitizers

  2. Doxorubicin-mediated radiosensitivity in multicellular spheroids from a lung cancer cell line is enhanced by composite micelle encapsulation

    Directory of Open Access Journals (Sweden)

    Xu WH

    2012-05-01

    Full Text Available Wen-Hong Xu,1 Min Han,2 Qi Dong,3 Zhi-Xuan Fu,3 Yuan-Yuan Diao,2 Hai Liu,3 Jing Xu,3 Hong-Liang Jiang,4 Su-Zhan Zhang,3 Shu Zheng,3 Jian-Qing Gao,2 Qi-Chun Wei11Department of Radiation Oncology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, 2Institute of Pharmaceutics, College of Pharmaceutical Sciences, 3Cancer Institute (Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, The Second Affiliated Hospital, School of Medicine, 4Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, Zhejiang, ChinaBackground: The purpose of this study is to evaluate the efficacy of composite doxorubicin-loaded micelles for enhancing doxorubicin radiosensitivity in multicellular spheroids from a non-small cell lung cancer cell line.Methods: A novel composite doxorubicin-loaded micelle consisting of polyethylene glycol-polycaprolactone/Pluronic P105 was developed, and carrier-mediated doxorubicin accumulation and release from multicellular spheroids was evaluated. We used confocal laser scanning microscopy and flow cytometry to study the accumulation and efflux of doxorubicin from A549 multicellular spheroids. Doxorubicin radiosensitization and the combined effects of irradiation and doxorubicin on cell migration and proliferation were compared for the different doxorubicin delivery systems.Results: Confocal laser scanning microscopy and quantitative flow cytometry studies both verified that, for equivalent doxorubicin concentrations, composite doxorubicin-loaded micelles significantly enhanced cellular doxorubicin accumulation and inhibited doxorubicin release. Colony-forming assays demonstrated that composite doxorubicin-loaded micelles are radiosensitive, as shown by significantly reduced survival of cells treated by radiation + composite micelles compared with those treated with radiation + free doxorubicin or radiation alone. The multicellular spheroid migration area and

  3. Rapid-mixing studies of the mechanisms of chemical radiosensitization and protection in mammalian cells

    International Nuclear Information System (INIS)

    A continuous flow, rapid-mixing system has been constructed to measure the degree of radiosensitization or protection observable after incubation of Chinese hamster ovary cells at room temperature for periods from about 5 to 1000 ms with a number of radiation modifiers. In agreement with earlier results full sensitization by oxygen is obtained in only a few tens of milliseconds. Misonidazole (10 mM) sensitizes at very nearly the steady-state level (E.R. approximately 2.3) in about 300 ms. Similarly near maximum sensitization by 10 mM metronidazole is seen within the same period. For large effects to be observed in such short times makes unlikely the involvement of any biochemical modification of either the drug or cells. Radioprotection by 1M dimethyl sulphoxide reaches about 80% of the equilibrium control value within 850 ms. However if its mode of action involves scavenging of hydroxyl radicals in competition with cellular components, the necessity for very high concentrations in the immediate region of the cellular target would be expected to require longer diffusion times. Cysteamine (10 mM) shows no evidence of its substantial protective ability even after 850 ms incubation. This molecule, which alone in this group exists as an ion in neutral solution, may encounter considerable difficulty in entering the cells. (author)

  4. Developmental-stage-dependent radiosensitivity of neural cells in the ventricular zone of telencephalon in mouse and rat fetuses

    International Nuclear Information System (INIS)

    Pregnant ICR mice were treated with single whole-body X-radiation at a dose of 0.24 Gy on day 10, 13, or 15 of gestation. Fetuses were obtained from mothers during 1 and 24 hours after irradiation. Pyknotic cells in the ventricular zone of telencephalon were counted in serial histological sections. Incidence of pyknotic cells peaked during 6 and 9 hours after irradiation in each gestation day group. Then, dose-response curves were obtained 6 hours after 0-0.48 Gy of irradiation. All three dose-response curves showed clear linearity in the dose range lower than 0.24 Gy. Ratios of radiosensitivity estimated from the slopes of dose-response curves in day 10, 13, and 15 groups were 1, 1.4, and 0.4, respectively. These demonstrated that ventricular cells in the day 13 fetal telencephalon were the most radiosensitive among the three different age groups. In order to confirm the presence of the highly radiosensitive stage common to mammalian cerebral cortical histogenesis, pregnant F344 rats were treated with single whole-body gamma-irradiation at a dose of 0.48 Gy on day 13, 14, 15, 17, or 19 of gestation. The incidence of pyknotic cells in the ventricular zone of telencephalon was examined microscopically during 1 and 24 hours after irradiation. The peak incidence was shown 6 hours after irradiation in all the treated groups, and the highest peak incidence was shown in day-15-treated group. The developmental stage of telencephalon of day 15 rat fetuses was comparable to that of day 13 mouse fetuses. Thus, the highest radiosensitivity in terms of acute cell death was shown in the same developmental stage of brain development, i.e., the beginning phase of cerebral cortical histogenesis, in both mice and rats

  5. Radiosensitive effect of hypoxia-inducible factor 1α inhibitor YC-1 on hypoxic glioma SHG44 cell line

    International Nuclear Information System (INIS)

    Objective: To investigate the radiosensitive effect of hypoxia-inducible factor 1α (HIF-1α) inhibitor YC-1 on hypoxic glioma SHG44 cell line and its related mechanism. Methods: Glioma SHG44 cell line was cultured in normoxic (20% O2), continuous hypoxia (1% O2) for 12 h and 24 h, continuous hypoxia plus YC-1 was performed for 12 h and 24 h, respectively. The expression of HIF-1α was assessed by Western blot. The radiosensitivity was evaluated by the survival curve, and the sublethal damage repair (SLDR) ability was measured by dose-fraction experiment. Results: HIF-1α protein levels of glioma SHG44 cells were significantly increased after hypoxic cultures for 12 h and 24 h than those of the corresponding cells cultured in normoxic, while the radiosensitivity was lower. The OER (oxygen-enhancement ratio) of SHG44 cells in hypoxia for 12 h and 24 h were 1.22 and 1.37, respectively. By the further statistical analysis it was found that SLDR ability of glioma SHG44 was increased at hypoxia, and when irradiation was carried one at the interval of 8, 10, 12 h it was statistically significant (P<0.05). HIF-1α protein levels of glioma SHG44 cells cultured in hypoxia plus YC-1 for 12 h and 24 h were decreased significantly compared to the corresponding cells cultured in hypoxia only, while the radiosensitivity was significantly increased. the EF (enhancement factor) of YC-1 for glioma SHG44 cells at hypoxia for 12 h and 24 h was 1.27. By the further statistical analysis it was also found that SLDR ability was decreased significantly for hypoxic SHG44 cells which was co-cultured with YC-1, and at the interval of 8, 10, 12 h irradiation was statistically significant (P<0.05). Conclusion: YC-1 can increase the radiosensitivity of hypoxic glioma SHG44 cell line, and its mechanism is related to SLDR inhibited by YC-1. (authors)

  6. Study of enhancement of radiosensitivity in colon cancer carcinoma cell line HT-29 by celecoxib in vitro and in vivo

    International Nuclear Information System (INIS)

    Objective: To evaluate the radiosensitizing effect of Celecoxib, a selective cyclooxygenase-2 inhibitor, on colonic carcinoma cell line HT-29 in vivo, and to probe the underlying mechanisms. Methods: Colonic carcinoma cell line HT-29 was managed in vitro, and was treated by different concentration of Celecoxib, and the cell radiosensitivity was analyzed by colony formation unit assays; the change of tumor volume was observed by establishing the bear-tumor mice model of colonic carcinoma and drawing the tumor growth curve under different conditions; the expression of VEGF in colonic carcinoma tissues was detected by Immunohistochemistry assay. Results: The colony formation unit assays showed SER was respectively 1.304 and 1.475 in different groups which were combined with Celecoxib (30 μmol/L and 50 μmol/L). The tumor growth curve was used to do determination in these groups. When radiation was used combined with Celecoxib increase of tumor volume was the slowest. The expression level of VEGF in group Celecoxib was proved lower than that in the other groups (P<0.05). Conclusion: Celecoxib in vitro and in vivo could enhance the radiosensitivity in colon cancer carcinoma cell line HT-29 and inhibiting tumor angiogenesis maybe one of the underlying mechanisms. (authors)

  7. Effects of resveratrol and methoxyamine on the radiosensitivity of iododeoxyuridine in U87MG glioblastoma cell line.

    Science.gov (United States)

    Khoei, Samideh; Shoja, Mohsen; Mostaar, Ahmad; Faeghi, Fariborz

    2016-06-01

    The purpose of this study was to evaluate the combination effect of resveratrol and methoxyamine on radiosensitivity of iododeoxyuridine in spheroid culture of U87MG glioblastoma cell line using colony formation and alkaline comet assays. Spheroids on day-20 with 350 µm diameters were treated with 20 µM resveratrol and/or 6 mM methoxyamine and/or 1 µM iododeoxyuridine for one volume doubling time (67 h), and then irradiated with 2 Gy gamma-radiation ((60)Co) in different groups. After treatment, viability of the cells, colony forming ability and DNA damages were obtained by blue dye exclusion, colony formation and alkaline comet assay, respectively. Our results showed that methoxyamine and resveratrol could significantly reduce colony number and induce the DNA damages of glioblastoma spheroid cells treated with iododeoxyuridine in combination with gamma-rays. Therefore, methoxyamine as base excision repair inhibitor and resveratrol as hypoxia inducible factor 1-alpha inhibitor in combination with iododeoxyuridine as radiosensitizer enhanced the radiosensitization of glioblastoma spheroid cells. PMID:26748400

  8. Radiation-induced DNA damage and repair in radiosensitive and radioresistant human tumour cells measured by field inversion gel electrophoresis

    International Nuclear Information System (INIS)

    Radiation-induced DNA damage induction and repair was measured in two human squamous carcinoma cell lines with differing radiosensitivities. Experiments were carried out with field inversion gel electrophoresis (FIGE), adapted to measure DNA double strand break (DSB) induction and repair in unlabelled cells. The sensitivity of the method was increased by introducing a hybridization membrane into the agarose gel. Damaged DNA accumulated on one spot on the membrane resulting in high local concentrations. This DNA was quantified using radioactively-labelled total human DNA as a probe. Radiosensitivity differences at physiological temperatures could not be explained by differences in either induction or repair of DNA damage as measured by pulsed field gel electrophoresis. (author)

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

    International Nuclear Information System (INIS)

    Purpose: To assess the relative radiosensitivities of a large collection of melanoma cell lines and to determine whether pharmacologic inhibition of mutant B-RAF with PLX-4032 can radiosensitize B-Raf+ melanoma cells. Materials and methods: A large collection of melanoma cell lines (n = 37) were treated with 0-8 Gy IR and clonogenic survival assays used to generate survival curves to rank relative radiosensitivities among the cell lines. The ability of a B-RAF inhibitor, PLX-4032, to radiosensitize highly radioresistant B-Raf+ cells was also assessed by clonogenic cell survival and spheroid invasion assays and the effects of treatment on the cell cycle assessed by FACS. Results: Melanoma cell lines displayed a very large, heterogeneous range of SF2 values (1.002-0.053) with a mean of 0.51. Cell lines with surviving fractions of 0.29 or less at SF2 and SF4 were observed at a high frequency of 18.9% and 70.2%, respectively. Treatment of B-Raf+ cells with the B-RAF inhibitor PLX-4032 in combination with radiation provided enhanced inhibition of both colony formation and invasion, and radiosensitized cells through an increase in G1 arrest. Conclusions: Our data suggest that melanomas are not uniformly radioresistant with a significant subset displaying inherent radiosensitivity. Pharmacologic inhibition of B-RAF with PLX-4032 effectively radiosensitized B-Raf+ melanoma cells suggesting that this combination approach could provide improved radiotherapeutic response in B-Raf+ melanoma patients.

  10. Radiosensitizing Effect of Schinifoline from Zanthoxylum schinifolium Sieb et Zucc on Human Non-Small Cell Lung Cancer A549 Cells: A Preliminary in Vitro Investigation

    Directory of Open Access Journals (Sweden)

    Cheng-Fang Wang

    2014-12-01

    Full Text Available Schinifoline (SF, a 4-quinolinone derivative, was found in Zanthoxylum schinifolium for the first time. 4-Quinolinone moieties are thought to have cytotoxic activity and are often used as a tubulin polymerization inhibitors, heterogeneous enzyme inhibitors and antiplatelet agents. However, very little information respect to radiosensitization has focused on SF. This work aimed to investigate the radiosensitizing effect of SF on A549 cells. The cell viability results indicated cytotoxicity of SF on A549 cells, with IC50 values of 33.7 ± 2.4, 21.9 ± 1.9 and 16.8 ± 2.2 μg/mL, respectively, after 6, 12, 24 h treatment with different concentrations, and the 10% or 20% IC50 concentration during 12 h was applied in later experiments. The results of cell proliferative inhibition and clonogenic assay showed that SF enhanced the radiosensitivity of A549 cells when applied before 60Co γ-irradiation and this effect was mainly time and concentration dependent. The flow cytometric data indicated that SF treatment before the irradiation increased the G2/M phase, thus improving the radiosensitivity of A549, leading to cell apoptosis. This paper is the first study that describes the in vitro radiosensitising, cell cycle and apoptotic-inducing effects of schinifoline.

  11. Relationship between telomere length and radiosensitivity of human cancer cell lines induced by heavy ion irradiation

    International Nuclear Information System (INIS)

    Telomere length is associated with both cancer incidence and cancer mortality. Low linear energy transfer (LET) induced telomere shortening and change in telomerase activity have been studied. However, no information about high LET induced telomere length and telomerase activity alteration was available currently. Here we investigated carbon ions irradiation induced telomerase activity and its expression in mRNA and protein levels. Results indicated that one of the components for telomerase, human telomerase reverse transcriptase (hTERT), was significantly affected by carbon ions irradiation, thus regulated telomerase activity after ionizing irradiation. For further investigate factors involved in telomerase activity, four different cell lines were used. BRCA1 and DNA-PK have been identified to be associated with telomerase activity regulation. In summary, the radiosensitivity of human cancer cell lines after carbon ions irradiation is related to telomerase activity, which is directly regulated by hTERT expression, BRCA1 and DNA-PK statues may play important parts in this regulation. (author)

  12. Experimental study on central nervous toxicity of 'misonidazole' a hypoxic cell radiosensitizer

    International Nuclear Information System (INIS)

    'Misonidazole', a radiosensitizer for hypoxic cells is expected to be applied to the treatment of malignant tumors, but its side effect becomes a subject of study, because its effective dose is close to its lethal dose. The auther performed experiments with mice on the central nervous toxicity, which is the most lethal of the side effects of Misonidazole, with the following results; 1. The abrupt death seen after the administration of a large dose of Misonidazole was attributable to the central nervous toxicity. LD50 for d.d. strain mouse was 1.55 mg per body weight g. 2. The used mice always developed convulsion before death. But the administration of anticonvulsant failed to free them from death. 3. Autopsy findings were such abnormal ones as the degeneration and exfoliation of nerve cells and diapedetic focus. After sacrifice, however, no findings indicative of disturbance of central nerve could be detected. 4. Misonidazole, even in a small divided dose, left intracerebral retention, though slightly, indicating that its accumulation in the brain would be increased with increase in the dose. 5. The disturbance of central nerve was not exacerbated by the whole brain irradiation with Misonidazole. (author)

  13. REG Iα activates c-Jun through MAPK pathways to enhance the radiosensitivity of squamous esophageal cancer cells.

    Science.gov (United States)

    Wakita, Akiyuki; Motoyama, Satoru; Sato, Yusuke; Koyota, Souichi; Usami, Shuetsu; Yoshino, Kei; Sasaki, Tomohiko; Imai, Kazuhiro; Saito, Hajime; Minamiya, Yoshihiro

    2015-07-01

    Identification of the key molecules that mediate susceptibility to anticancer treatments would be highly desirable. Based on clinical and cell biological studies, we recently proposed that regenerating gene (REG) Iα may be such a molecule. In the present study, we hypothesized that REG Iα increases radiosensitivity through activation of mitogen-activated protein kinase (MAPK) pathways. To test that idea, we transfected TE-5 and TE-9 squamous esophageal cancer cells with REG Iα and examined its involvement in MAPK signaling and its effect on susceptibility to radiotherapy. We found that REG Iα-expressing cells showed increased expression of c-Jun messenger RNA (mRNA) and phospho-c-Jun protein mediated via the c-Jun N-terminal kinase (JNK) pathway and extracellular signal-regulated kinase (ERK) pathway, as well as increased radiosensitivity. Immunohistochemical analysis confirmed the activation of c-Jun in tumors expressing REG Iα. Collectively, these findings suggest that REG Iα activates c-Jun via the JNK and ERK pathway, thereby enhancing radiosensitivity. PMID:25656613

  14. Curcumin and trans-resveratrol exert cell cycle-dependent radioprotective or radiosensitizing effects as elucidated by the PCC and G2-assay

    Energy Technology Data Exchange (ETDEWEB)

    Sebastià, N., E-mail: natividad.sebastia@uv.es [Radiation Protection Service, IIS La Fe, Health Research Institute La Fe, Valencia (Spain); Montoro, A. [Radiation Protection Service, Universitary and Politechnic Hospital La Fe, Valencia (Spain); Grupo de Investigación Biomédica en Imagen GIBI230, IIS La Fe, Health Research Institute La Fe, Valencia (Spain); Unidad Mixta de Investigación en Endocrinología, Nutrición y Dietética Clínica, IIS La Fe, Health Research Institute La Fe, Valencia (Spain); Hervás, D. [Biostatistics Unit, IIS La Fe, Health Research Institute La Fe, Valencia (Spain); Pantelias, G.; Hatzi, V.I. [Institute of Nuclear and Radiological Sciences and Technology, Energy and Safety, National Centre for Scientific Research “Demokritos”, Aghia Paraskevi, Athens (Greece); Soriano, J.M. [Grupo de Investigación Biomédica en Imagen GIBI230, IIS La Fe, Health Research Institute La Fe, Valencia (Spain); Unidad Mixta de Investigación en Endocrinología, Nutrición y Dietética Clínica, IIS La Fe, Health Research Institute La Fe, Valencia (Spain); Department of Preventive Medicine and Public Health, Faculty of Pharmacy, University of Valencia, Burjassot, Valencia (Spain); Villaescusa, J.I. [Radiation Protection Service, Universitary and Politechnic Hospital La Fe, Valencia (Spain); and others

    2014-08-15

    Highlights: • Curcumin and trans-resveratrol can exert radioprotective or radiosensitizing effects. • The mechanisms underlying such dual action were elucidated using the PCC and G2-assay. • Radioprotection occurs in non-cycling cells exposed to curcumin and resveratrol. • Radiosensitization occurs in cycling cells exposed to the chemicals. • G2-checkpoint abrogation by the chemicals underlies the radiosensitizing mechanism. - Abstract: Curcumin and trans-resveratrol are well-known antioxidant polyphenols with radiomodulatory properties, radioprotecting non-cancerous cells while radiosensitizing tumor cells. This dual action may be the result of their radical scavenging properties and their effects on cell-cycle checkpoints that are activated in response to radiation-induced chromosomal damage. It could be also caused by their effect on regulatory pathways with impact on detoxification enzymes, the up-regulation of endogenous protective systems, and cell-cycle-dependent processes of DNA damage. This work aims to elucidate the mechanisms underlying the dual action of these polyphenols and investigates under which conditions they exhibit radioprotecting or radiosensitizing properties. The peripheral blood lymphocyte test system was used, applying concentrations ranging from 1.4 to 140 μM curcumin and 2.2 to 220 μM trans-resveratrol. The experimental design focuses first on their radioprotective effects in non-cycling lymphocytes, as uniquely visualized using cell fusion-mediated premature chromosome condensation, excluding, thus, cell-cycle interference to repair processes and activation of checkpoints. Second, the radiosensitizing potential of these chemicals on the induction of chromatid breaks in cultured lymphocytes following G2-phase irradiation was evaluated by a standardized G2-chromosomal radiosensitivity predictive assay. This assay uses caffeine for G2-checkpoint abrogation and it was applied to obtain an internal control for radiosensitivity

  15. Curcumin and trans-resveratrol exert cell cycle-dependent radioprotective or radiosensitizing effects as elucidated by the PCC and G2-assay

    International Nuclear Information System (INIS)

    Highlights: • Curcumin and trans-resveratrol can exert radioprotective or radiosensitizing effects. • The mechanisms underlying such dual action were elucidated using the PCC and G2-assay. • Radioprotection occurs in non-cycling cells exposed to curcumin and resveratrol. • Radiosensitization occurs in cycling cells exposed to the chemicals. • G2-checkpoint abrogation by the chemicals underlies the radiosensitizing mechanism. - Abstract: Curcumin and trans-resveratrol are well-known antioxidant polyphenols with radiomodulatory properties, radioprotecting non-cancerous cells while radiosensitizing tumor cells. This dual action may be the result of their radical scavenging properties and their effects on cell-cycle checkpoints that are activated in response to radiation-induced chromosomal damage. It could be also caused by their effect on regulatory pathways with impact on detoxification enzymes, the up-regulation of endogenous protective systems, and cell-cycle-dependent processes of DNA damage. This work aims to elucidate the mechanisms underlying the dual action of these polyphenols and investigates under which conditions they exhibit radioprotecting or radiosensitizing properties. The peripheral blood lymphocyte test system was used, applying concentrations ranging from 1.4 to 140 μM curcumin and 2.2 to 220 μM trans-resveratrol. The experimental design focuses first on their radioprotective effects in non-cycling lymphocytes, as uniquely visualized using cell fusion-mediated premature chromosome condensation, excluding, thus, cell-cycle interference to repair processes and activation of checkpoints. Second, the radiosensitizing potential of these chemicals on the induction of chromatid breaks in cultured lymphocytes following G2-phase irradiation was evaluated by a standardized G2-chromosomal radiosensitivity predictive assay. This assay uses caffeine for G2-checkpoint abrogation and it was applied to obtain an internal control for radiosensitivity

  16. Downregulation of cell division cycle 25 homolog C reduces the radiosensitivity and proliferation activity of esophageal squamous cell carcinoma.

    Science.gov (United States)

    Yin, Yachao; Dou, Xiaoyan; Duan, Shimiao; Zhang, Lei; Xu, Quanjing; Li, Hongwei; Li, Duojie

    2016-09-30

    Radiation therapy is one of the most important methods of contemporary cancer treatment. Cells in the G2 and M phases are more sensitive to radiation therapy, and cell division cycle 25 homolog C (CDC25C) is essential in shifting the cell cycle between these two phases. In this study, the knockdown of CDC25C in human esophageal squamous carcinoma EC9706 cells was mediated by transfecting shRNA against human CDC25C-subcloning into pGV248. The levels of CDC25C mRNA and protein expression were assessed by reverse transcription-polymerase chain reaction (RT-PCR) and western blotting, respectively. Moreover, cell proliferation and radiosensitivity were measured. Stable CDC25C-knockdown EC9706 cell lines were successfully established. Furthermore, the proliferation of both control and CDC25C-shRNA-EC9706 cells was inhibited after the cells were treated with increasing X-ray doses, and the proliferation of the control cells was affected more significantly (p<0.05). Moreover, cell colony formation assays allowed us to reach the same conclusion. Taken together, our experiments demonstrated that the knockdown of CDC25C can reduce both the radiotherapy sensitivity and the proliferation activity of EC9706 cells. Thus, CDC25C might be a potential biomarker for radiotherapy treatment. PMID:27188256

  17. Intrinsic radiosensitivity and DNA double-strand breaks in human cells

    International Nuclear Information System (INIS)

    Among the large spectrum of DNA damage induced by radiation, DNA double-strand breaks (DSBs) are considered, to date, as the key-lesions responsible for the cell killing. However, although it was always intuitive to radio-biologists, such a conclusion has only been reached after technical developments and conceptual advances and remains consensual rather than demonstrated formally. In this article, we have reviewed the results that have lead to the conclusion that the assessment of successful DSB repair can be the basis of reliable assays predictive of the clinical response to radiotherapy and some chemotherapeutic treatments. We have discussed a number of technical artifacts, the biases due to the extrapolation of data obtained in yeast and rodent model systems to the human situation and the variety of phenotypes observed in human cells and in particular: 1) the most recent techniques developed, based on immunofluorescence, which have revolutionized our understanding of the molecular events occurring early after irradiation but have also raised the crucial questions about the choice of techniques to. assess DSB repair and their specificity for different steps of the repair process; 2) While the homologous recombination repair pathway is predominant in yeasts, its importance in human cells appears less obvious, and raises the problem that the existence of randomized repair events may produce many more errors in human cells than in small genome organisms; 3) the impairment of DSB repair is observed in a plethora of genetic diseases, leading to radiosensitivity, immunodeficiency and sometimes cancer-proneness, but the low frequency and the pleiotropism of such diseases makes difficult the development of a single predictive assay. Therefore, although complete DSB repair appears to be crucial for cell survival, further research is still needed to provide innovative techniques for measuring repair which can be successfully transferred to the clinic and used to ensure

  18. Radiosensitizing effect of nitric oxide in tumor cells and experimental tumors irradiated with gamma rays and proton beams

    International Nuclear Information System (INIS)

    Nitric oxide (NO) has been reported to be a radiosensitizer of mammalian cells under hypoxic conditions. In a previous study, we demonstrated an enhancement in radiation response induced by NO in mouse tumor cells under aerobic conditions, with an increasing effect as a function of malignancy. The aim of the present study was to evaluate the effect of NO in tumor cells and in experimental tumors irradiated with γ rays and proton beams. Irradiations were performed with a 137Cs γ source and with proton beams generated by the TANDAR accelerator. Tumor cells were treated with the NO donor DETA-NO and the sensitizer enhancement ratio (SER) was calculated using the α parameter of the survival curve fitted to the linear-quadratic model. Tumor cells irradiated with protons were radio sensitized by DETA-NO only in the more malignant cells irradiated with low LET protons (2.69±0.08 keV/μm). For higher LET protons there were no radiosensitizing effect. For human tumor cells pre-treated with DETA-NO and irradiated with γ rays, a significantly greater effect was demonstrated in the malignant cells (MCF-7) as compared with the near normal cells (HBL-100). Moreover, a significant decrease in tumor growth was demonstrated in mice pre-treated with the NO donor spermine and irradiated with γ rays and low LET protons as compared with mice irradiated without pre-treatment with the NO donor. In conclusion, we demonstrated a differential effect of NO as a radiosensitizer of malignant cells, both with γ rays and low LET protons. This selectivity, coupled to the in vivo inhibition of tumor growth, is of great interest for the potential use of NO releasing agents in radiotherapy. (author)

  19. Screening radiosensitizing-related genes mediated by elemene in lung adenocarcinoma A549 cells by using gene chip

    International Nuclear Information System (INIS)

    Objective: To screen radiosensitizing-related genes mediated by elemene in lung adenocarcinoma A549 cells by using gene chip. Methods: MTT test was used to calculate the IC50 of elemene. (1) The effect of radiosensitivity was detected by colony forming assay. A549 cells were divided into 2 groups: radiation group and radiation + elemene group. Oligonucleotide chip was used to screen the gene expression changes of A549 cells from these 2 groups. The up-regulated gene Egr-1 and the down-regulated gene CyclinD1 were selected to undergo RT-PCR so as to confirm the reliability of the result. Results: MTT test showed the elemene inhibited the proliferation of the A549 cells dose-dependently. The IC50 value of elemene on the A549 cells was 120 mg/L. (2) 10 mg/L elemene had radiosensitising effect on A549 cells.The values of SERD0 and SERDq obtained from the survival curve were (1.54±0. 20) and (1.43±0.15) respectively. Gene chip screened 122 differentially-expressed genes, including 89 up-regulated genes and 33 down-regulated genes. (3) These altered genes could be related to cell structure, substance metabolism,cell proliferation, cell differentiation, signal transduction, material transport, DNA repair, apoptosis, immune response and so forth. The RT-PCR results of Egr-1 and Cyclin D1 were consistent with the gene chip analysis. Conclusions: The mechanism of elemene enhancing the radiosensitivity of lung adenocarcinoma A549 cells is the result of participation and collaboration of multiple genes. Further study of the newly-discovered differentially-expressed gene helps find out new radiosensitizational targets of elemene. (authors)

  20. Cloning of smac gene and its overexpression effects on radiosensitivity of HeLa cells to γ-rays

    International Nuclear Information System (INIS)

    Objective: To clone smac gene and construct eukaryocytic expression vector pcDNA3.1/ smac. The smac gene was transfected into HeLa cells to explore the effects of over-expression of extrinsic smac gene on radiosensitivity to γ-rays of HeLa cells. Methods: The full-length smac gene was amplified from total RNA of HeLa cells by RTPCR. The RTPCR product was ligated with the vector pcDNA3.1 and sequenced. The correct pcDNA3.1/smac was transfected into HeLa cells. The expression of smac gene was tested by RTPCR and Western blot. The cellular growth inhibition rates were evaluated by MTT 48 horns after irradiation with different doses of γ-rays. Results: Recombinant eukaryocytic expression vector pcDNA3.1/smac was successfully constructed. RTPCR and Western blot results indicated that the expression of smac gene of HeLa/smac cells was significantly enhanced compared with the expression of smac gene of HeLa/pcDNA3.1 and HeLa cells. 48 hours after different doses of γ-ray irradiation was significantly higher in pcDNA3.1/smac transfected HeLa/smac cells than those of non-transfected HeLa cells or pcDNA3.1 transfected HeLa/pcDNA3.1 cells, inhabitation rates were 38.85%, 17.64% and 20.32%, respectively. Conclusions: smac gene was successfully cloned. Extrinsic smac gene over-expression could significantly enhance radiosensitivity to γ-ray of HeLa cells, which would herald a new approach to improve radiosensitivity of cervical cancer. (authors)

  1. Radiosensitization of esophageal carcinoma cells by the silencing of BMI-1.

    Science.gov (United States)

    Yang, Xing-Xiao; Sang, Mei-Xiang; Zhu, Shu-Chai; Liu, Zhi-Kun; Ma, Ming

    2016-06-01

    Radiotherapy (RT) has been widely used to treat cancer patients, particularly esophageal cancer patients. B-cell-specific Moloney murine leukemia virus integration site-1 (BMI-1) plays an important role in promoting the growth of cancer cells after exposure to irradiation. The present study aimed to characterize the effects of BMI-1 on the proliferation and invasion of cancer cells, as well as the mechanism involved in the regulation of the growth of esophageal cancer ECA109 and TE13 cells. The expression levels of the BMI-1 gene and protein in esophageal cancer ECA109 and TE13 cells were determined by quantitative PCR and western blotting after transfection. Co-immunoprecipitation (Co-IP) assay was employed to detect the interaction of BMI-1 with r-H2AX and H2AK119ub. We used flow cytometry to analyze the cell cycle distribution and apoptosis of transfected cells after irradiation or not, and examined cellular growth and invasion in vitro by MTS and Transwell assays. The results revealed that shRNA targeting the BMI-1 gene and protein downregulated BMI-1 expression after transfection for 24 h. The proliferation and invasion of tumor cells in the BMI-1‑shRNA group were suppressed after RT. In addition, the interaction of BMI-1, H2AK119ub and r-H2AX was increased after exposure to IR, followed by an increased apoptosis rate and decreased percentage of cells arrested at the G2/M phase after irradiation and silencing of BMI-1 by shRNA. Knockdown of BMI-1 expression decreased the phosphorylation of H2AX, upregulated p16, and induced the radiosensitivity of esophageal cancer ECA109 and TE13 cells in vitro and significantly inhibited the growth and invasion of tumor cells. The mechanisms were found to be abrogation of cell cycle arrest at the G2/M stage and promotion of apoptosis. PMID:27108688

  2. 3-Methyl pyruvate enhances radiosensitivity through increasing mitochondria-derived reactive oxygen species in tumor cell lines

    International Nuclear Information System (INIS)

    Considerable interest has recently been focused on the special characteristics of cancer metabolism, and several drugs designed to modulate cancer metabolism have been tested as potential anticancer agents. To date, however, very few studies have been conducted to investigate the combined effects of anticancer drugs and radiotherapy. In this study, to evaluate the role of mitochondria-derived reactive oxygen species (ROS) in the radiation-induced cell death of tumor cells, we have examined the effect of 3-methyl pyruvate (MP). MP is a membrane-permeable pyruvate derivative that is capable of activating mitochondrial energy metabolism in human lung carcinoma A549 cells and murine squamous carcinoma SCCVII cells. Pretreatment with MP significantly enhanced radiation-induced cell death in both cell lines, and also led to increases in the mitochondrial membrane potential, intracellular adenosine triphosphate content, and mitochondria-derived ROS production following the exposure of the cells to X-rays. In A549 cells, MP-induced radiosensitization was completely abolished by vitamin C. In contrast, it was partially abolished in SCCVII cells. These results therefore suggest that the treatment of the cells with MP induced radiosensitization via the production of excess mitochondria-derived ROS in tumor cells. (author)

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

    International Nuclear Information System (INIS)

    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)

  4. Radiosensitivity increases with differentiation status of murine hemopoietic progenitor cells selected using enriched marrow subpopulations and recombinant growth factors

    International Nuclear Information System (INIS)

    The radiosensitivity of populations of colony-forming cells (CFC) in murine bone marrow was investigated using different recombinant colony-stimulating factors (CSFs; murine IL-3 and granulocyte-macrophage CSF and human granulocyte CSF), or purified murine macrophage CSF. With unfractionated normal bone marrow the CFC increased in radiosensitivity as they progressed through the granulocyte lineage. The D0 values ranged from 129 +/- 12 cGy for CFC stimulated with GM-CSF down to 42 +/- 2 cGy after stimulation with G-CSF. IL-3 stimulated a CFC population which gave the only survival curve with a shoulder (n = 1.9 +/- 0.3). With semipurified populations of primitive or bipotential CFC, D0 values were generally lower with respect to the equivalent values for unpurified bone marrow (range 62 +/- 7 cGy to 135 +/- 7 cGy). Changes in cluster/colony ratio and colony morphology together possibly with products of accessory cells influence the interpretation of the radiosensitivity parameters

  5. MicroRNA-148b enhances the radiosensitivity of non-Hodgkin's lymphoma cells by promoting radiation-induced apoptosis

    International Nuclear Information System (INIS)

    Growing evidence has demonstrated that microRNAs (miRNAs) play an important role in regulating cellular radiosensitivity. This study aimed to explore the role of miRNAs in non-Hodgkin's lymphoma (NHL) radiosensitivity. Microarray was employed to compare the miRNA expression profiles in B cell lymphoma cell line Raji before and after a 2-Gy dose of radiation. A total of 20 differentially expressed miRNAs were identified including 10 up-regulated and 10 down-regulated (defined as P <0.05). Among the differentially expressed miRNAs, miR-148b was up-regulated 1.53-fold in response to radiation treatment. A quantitative real-time polymerase chain reaction (PCR) assay confirmed the up-regulation of miR-148b after radiation. Transient transfection experiments showed that miR-148b was up-regulated by miR-148b mimic and down-regulated by miR-148b inhibitor in the Raji cells. A proliferation assay showed that miR-148b could inhibit the proliferation of Raji cells before and after radiation. A clonogenic assay demonstrated that miR-148b sensitized Raji cells to radiotherapy. MiR-148b did not affect the cell cycle profile of post-radiation Raji cells compared with controls. An apoptosis assay showed that miR-148b enhanced apoptosis of Raji cells after irradiation. Taken together, these results demonstrate that miR-148b increased the radiosensitivity of NHL cells probably by promoting radiation-induced apoptosis, which suggests that miR-148b plays an important role in the response of NHL to ionizing radiation. (author)

  6. Effect of silencing of ATM expression by siRNA on radiosensitivity of human lung adenocarcinoma A549 cells

    International Nuclear Information System (INIS)

    Objective: To investigate the effect of silencing of ataxia-telangiectasia mutated (ATM) expression by plasmid-mediated RNA interference on the radiosensitivity of human lung adenocarcinoma A549 cells. Methods: Eukaryotic expression plasmid containing ATM small interfering RNA (siRNA) (pSilencer2.1-ATM), as well as pSilencer2.1-nonspecific, was constructed.Lung adenocarcinoma A549 cells were divided into positive group, negative group,and control group to be transfected with pSilencer2.1-ATM, pSilencer2.1-nonspecific, and no plasmid, respectively. The mRNA and protein expression of ATM was measured by RT-PCR and Western blot, respectively. The change in cell radiosensitivity was observed by colony-forming assay. Cell cycle and cell apoptosis were analyzed by flow cytometry. Results: The eukaryotic expression plasmid containing ATM siRNA was successfully constructed. The RT-PCR and Western blot demonstrated that the expression of ATM was down-regulated in the positive group. The sensitization enhancement ratios (D0 ratios) for the positive group and negative group were 1.50 and 1.01, respectively. The flow cytometry revealed that the proportions of A549 cells in G1 and G2/M phases were significantly lower in the positive group than in the control group (51.27% vs 61.85%, P = 0.012; 6.34% vs 10.91%, P = 0.008) and that the apoptosis rate was significantly higher in the positive group than in the control group and negative group (49.31% vs 13.58%, P = 0.000; 49.31% vs 13.17%, P = 0.000). Conclusions: Silencing of ATM expression may increase the radiosensitivity of human lung adenocarcinoma A549 cells, probably by affecting the cell cycle and promoting cell apoptosis. (authors)

  7. Transformed human mesenchymal stem cells are more radiosensitive compared to their cells of origin in normoxia and in physiological hypoxia

    International Nuclear Information System (INIS)

    The full text of the publication follows. Purpose: The presence of hypoxic regions in tumours is associated with the recurrence of solid tumours after treatment with radiotherapy and thought to be an important element in defining the stem cell niche. We studied the effect of hypoxia on the response to radiation in sequentially transformed human mesenchymal stem cells (MSC) to investigate how the genetic events that lead to tumorigenicity influence the cellular response to radiation under hypoxic and normoxic conditions. Experimental Design: Human bone marrow derived SH2+, SH4+, Stro-1+ MSC were transformed step-wise by retroviral transfection of hTERT, HPV-16 E6 and E7, SV40 small T antigen and oncogenic H-ras. Cells were grown and irradiated with 0, 1 to 5 Gy, X-Ray at 20%, 5% and 1% oxygen tensions. Cytotoxicity, DNA double-strand break (DSB) repair and checkpoint signalling were compared between cells at three different stages of transformation and in different oxygen concentrations. Results: MSCs became more radiosensitive at each point during step-wise transformation, and this effect persisted when cells were irradiated in physiological hypoxia. Increased cytotoxicity of radiation was associated with increased residual DNA DSB at 24 post X-irradiation assessed by gamma-H2AX foci. Growth and irradiation in 1% but not 5% oxygen promoted increased radioresistance compared to growth in 20% oxygen but did not change the relative sensitivity of tumorigenic cells compared to parental cells. Activation of checkpoint signalling before and after single radiation doses is more marked in tumorigenic cells compared to parental lines, and is not altered when cells are irradiated and grown in hypoxic conditions. Conclusions: These data show that tumorigenic cells are more radiosensitive compared to non-tumorigenic parental cells in both normoxic and hypoxic conditions. 1% hypoxia promotes radioresistance in all cells. Checkpoint signalling is up-regulated in tumorigenic

  8. Influence the oxidant action of selenium in radiosensitivity induction and cell death in yeast Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    cells when they are challenged with ionizing radiation produced by 60Co. For this, we assessed whether selenium causes oxidative damage to cell and cell death. After that, we assessed whether differences in the oxidative damage occurs after the cells be treated with selenium and gamma irradiation. Our results showed that selenium has a radiosensitizing function playing a oxidant role in yeast cell. (author)

  9. Inhibition of cyclooxygenase-2 activity by celecoxib does not lead to radiosensitization of human prostate cancer cells in vitro

    International Nuclear Information System (INIS)

    Purpose: To evaluate the potential radiosensitizing effect of the specific COX-2 inhibitor celecoxib (Celebrex[reg]) on prostate carcinoma cells in vitro. Materials and methods: The influence of celecoxib (concentration range 5 to 75 μM) on radiation-induced cellular and clonogenic survival was investigated in prostate carcinoma cell lines PC-3, DU145, LNCaP and normal prostate epithelial cells (PrEC). Western blot analysis and ELISA were used to determine the impact of radiation alone or radiation combined with celecoxib treatment on COX-2 expression and prostaglandin E2 synthesis. To evaluate induction of celecoxib-induced apoptosis cell cycle analysis has been performed. Results: Celecoxib (5, 10 and 25 μM) in combination with single-dose irradiation of 2 Gy induced a significant radiosensitization in normal prostate epithelial cells which could not be observed for any of the prostate carcinoma cell lines investigated. Increased COX-2 protein expression in PC-3 cells was obvious only after IR with 15 Gy, while PGE2 production was elevated following irradiation (2-15 Gy) in a dose-dependent manner. Treatment with celecoxib alone or in combination with IR led to a dose-dependent increase in COX-2 protein expression. Nevertheless pre-treatment with celecoxib caused a marked reduction of radiation-induced enzyme activity as tested at the level of PGE2 production, both in PC-3 and DU145 cells. Following fractionated irradiation with single doses of 2 Gy, elevated COX-2 protein expression as well as enhanced PGE2 production was observed already after the second fraction in PC-3 cells. Pre-treatment with celecoxib reduced the amount of PGE2 significantly, but not of COX-2 protein. Conclusions: Our data obtained for the human prostate cancer cell lines do not indicate that a marked inhibition of prostaglandin E2 synthesis by celecoxib leads to enhanced radiosensitization. Thus, in terms of radiosensitization the analysed prostate cancer cells can be classified as non

  10. Development of novel radiosensitizers for cancer therapy

    CERN Document Server

    Akamatsu, K

    2002-01-01

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

  11. ATM-Dependent Hyper-Radiosensitivity in Mammalian Cells Irradiated by Heavy Ions

    International Nuclear Information System (INIS)

    Purpose: Low-dose hyper-radiosensitivity (HRS) and the later appearing radioresistance (termed induced radioresistance [IRR]) was mainly studied in low linear energy transfer (LET) radiation with survival observation. The aim of this study was to find out whether equivalent hypersensitivity occurred in high LET radiation, and the roles of ataxia telangiectasia mutated (ATM) kinase. Methods and Materials: Survival and mutation were measured by clonogenic assay and HPRT mutation assay. ATM Ser1981 activation was detected by Western blotting and immunofluorescent staining. Pretreatment of specific ATM inhibitor (10 μM KU55933) and activator (20 μg/mL chloroquine) before carbon radiation were adopted to explore the involvement of ATM. The roles of ATM were also investigated in its G2/M checkpoint function with histone H3 phosphorylation analysis and flow cytometric assay, and DNA double strand break (DSB) repair function measured using γ-H2AX foci assay. Results: HRS/IRR was observed with survival and mutation in normal human skin fibroblast cells by carbon ions, while impaired in cells with intrinsic ATM deficiency or normal cells modified with specific ATM activator or inhibitor before irradiation. The dose-response pattern of ATM kinase activation was concordant with the transition from HRS to IRR. The ATM-dependent 'early' G2 checkpoint arrest and DNA DSB repair efficiency could explain the difference between HRS and IRR. Conclusions: These data demonstrate that the HRS/IRR by carbon ion radiation is an ATM-dependent phenomenon in the cellular response to DNA damage.

  12. Hepatocytes Determine the Hypoxic Microenvironment and Radiosensitivity of Colorectal Cancer Cells Through Production of Nitric Oxide That Targets Mitochondrial Respiration

    International Nuclear Information System (INIS)

    Purpose: To determine whether host hepatocytes may reverse hypoxic radioresistance through nitric oxide (NO)-induced oxygen sparing, in a model relevant to colorectal cancer (CRC) liver metastases. Methods and Materials: Hepatocytes and a panel of CRC cells were incubated in a tissue-mimetic coculture system with diffusion-limited oxygenation, and oxygen levels were monitored by an oxygen-sensing fluorescence probe. To activate endogenous NO production, cocultures were exposed to a cytokine mixture, and the expression of inducible nitric oxide synthase was analyzed by reverse transcription–polymerase chain reaction, Western blotting, and NO/nitrite production. The mitochondrial targets of NO were examined by enzymatic activity. To assess hypoxic radioresponse, cocultures were irradiated and reseeded for colonies. Results: Resting hepatocytes consumed 10-40 times more oxygen than mouse CT26 and human DLD-1, HT29, HCT116, and SW480 CRC cells, and thus seemed to be the major effectors of hypoxic conditioning. As a result, hepatocytes caused uniform radioprotection of tumor cells at a 1:1 ratio. Conversely, NO-producing hepatocytes radiosensitized all CRC cell lines more than 1.5-fold, similar to the effect of selective mitochondrial inhibitors. The radiosensitizing effect was associated with a respiratory self-arrest of hepatocytes at the level of aconitase and complex II, which resulted in profound reoxygenation of tumor cells through oxygen sparing. Nitric oxide–producing hepatocytes were at least 10 times more active than NO-producing macrophages to reverse hypoxia-induced radioresistance. Conclusions: Hepatocytes were the major determinants of the hypoxic microenvironment and radioresponse of CRC cells in our model of metabolic hypoxia. We provide evidence that reoxygenation and radiosensitization of hypoxic CRC cells can be achieved through oxygen sparing induced by endogenous NO production in host hepatocytes

  13. Relationship between radiosensitivity of human neonatal hematopoietic stem/progenitor cells and individual maternal/neonatal obstetric factors

    International Nuclear Information System (INIS)

    Hematopoietic stem/progenitor cells (HSPCs) in placental/umbilical cord blood (CB), which is neonatal peripheral blood, have increasingly been used for hematopoietic stem cell transplantations. It is likely HSPCs are sensitive to extracellular oxidative stresses, such as ionizing radiation and redox-directed chemotherapeutic agents. However, the radiosensitivity of HSPCs and neonatal hematopoietic system remains unclear. This study investigated the potential relationship between the radiosensitivity of HSPCs in CB, which was obtained from singleton and full-term deliveries, and maternal/neonatal obstetric factors. Freshly prepared CB CD34+ cells exposed to 2 Gy X-irradiation were assayed for hematopoietic progenitor cells such as colony-forming unit-granulocyte-macrophage (CFU-GM), burst-forming unit-erythroid (BFU-E), colony-forming unit-granulocyte-erythroid-macrophage-megakaryocyte (CFU-Mix), and colony-forming unit-megakaryocyte (CFU-Meg). As a result, the neonatal weight, placental weight, CB volume, total low-density (LD) cells, and CD34+ cells showed mutually significant positive correlations. The CB volume and total LD cells showed a significant reverse correlation with the surviving fraction of CFU-Meg. The surviving fraction of CFU-GM in spring (March-May) was significantly higher than that in autumn (September-November). The surviving fraction of CFU-Meg in the spring was significantly lower than that in the autumn. Male neonates showed a significantly higher surviving fraction of CFU-GM than female neonates. Contrarily, females showed a significantly higher surviving fraction of CFU-Meg than males. The present results suggest that the obstetric factors, such as the season of birth and neonatal gender, influence the radiosensitivity of neonatal hematopoiesis. (author)

  14. A Meta Analysis of Radiosensitivity on Non-small Cell Lung Cancer 
by Metronidazole Amino Acidum Natrium

    Directory of Open Access Journals (Sweden)

    Weiwei REN

    2012-06-01

    Full Text Available Background and objective The efficacy and safety of radiosensitivity on non-small cell lung cancer (NSCLC using metronidazole amino acidum natrium (CMNa are yet to be proven. This study evaluates the efficacy and safety of radiosensitivity on NSCLC by CMNa to provide references for further clinical practice and research. Methods Relevant randomized controlled trials (RCTs were obtained from the Cochrane library, Pubmed, EMbase, CBM, CNKI, VIP, and Wan Fang databases. Dates were searched through other means. RCTs of radiosensitivity on NSCLC by CMNa were included. The data included in the study were evaluated and analyzed using the Cochrane Collaboration's RevMan 5.1 software. Results A total of 21 RCTs were included. The results of the meta-analyses showed that the total effective rate of the test group that received CMNa plus radiotherapy was higher than that of the control group that received radiotherapy alone (OR=3.29, 95%CI: 2.47-4.39, P<0.000,01 or radiotherapy plus placebo (OR=3.65, 95%CI: 2.25-5.92, P<0.000,01, respectively. No significant differences were found in the quality of life between one and two-year survival rates (P>0.05. No significant differences were found among radiation pneumonitis, radiation esophagitis, hematological toxicity, and cardiotoxicity (P>0.05. Conclusion CMNa plus radiotherapy elicit beneficial effects in the treatment of NSCLC and produce fewer adverse effects. Therefore, this technique can be recommended and applied in clinics.

  15. Ectopically hTERT expressing adult human mesenchymal stem cells are less radiosensitive than their telomerase negative counterpart

    International Nuclear Information System (INIS)

    During the past several years increasing evidence indicating that the proliferation capacity of mammalian cells is highly radiosensitive, regardless of the species and the tissue of origin of the cells, has accumulated. It has also been shown that normal bone marrow cells of mice have a similar radiosensitivity to other mammalian cells so far tested. In this study, we investigated the genetic effects of ionizing radiation (2.5-15 Gy) on normal human mesenchymal stem cells and their telomerised counterpart hMSC-telo1. We evaluated overall genomic integrity, DNA damage/repair by applying a fluorescence-detected alkaline DNA unwinding assay together with Western blot analyses for phosphorylated H2AX and Q-FISH was applied for investigation of telomeric damage. Our results indicate that hMSC and TERT-immortalized hMSCs can cope with relatively high doses of γ-rays and that overall DNA repair is similar in the two cell lines. The telomeres were extensively destroyed after irradiation in both cell types suggesting that telomere caps are especially sensitive to radiation. The TERT-immortalized hMSCs showed higher stability at telomeric regions than primary hMSCs indicating that cells with long telomeres and high telomerase activity have the advantage of re-establishing the telomeric caps

  16. Influence of heat on the intracellular uptake and radiosensitization of 2-nitroimidazole hypoxic cell sensitizers in vitro

    International Nuclear Information System (INIS)

    The effect of elevated temperature (44 degrees) on the intracellular uptake of the 2-nitroimidazole hypoxic cell radiosensitizer, misonidazole (MIS), and analogues more hydrophilic than MIS was studied in Chinese hamster ovary cells. It was found that the intracellular uptake of these compounds which enter cells by restricted passive diffusion can be enhanced approximately 4-fold when incubated at 44 degrees compared to the uptake at 37 degrees. Peak intracellular uptake (expressed as the ratio of intracellular concentration to extracellular concentration) following incubation of cells in 2 mM MIS was 100% at 44 degrees but only 25% at 37 degrees. Furthermore, a short-term nonlethal heat pulse (44 degrees for 15 min) with MIS present caused a 2-fold enhancement in uptake which was sustained for an additional 45 min at 37 degrees. This same nonlethal heat pulse was found to induce a similar enhancement in uptake even when MIS was added at subsequent time intervals at 37 degrees. The heat pulse induced a time-related enhancement of uptake at 37 degrees which increased for 1 hr and persisted for at least 6 hr. Finally, in vitro radiosensitization studies of hypoxic Chinese hamster ovary cells showed that the nonlethal heat pulse of 44 degrees for 15 min could greatly enhance the sensitization by low concentrations (0.5 mM) of MIS added after heating due to increased intracellular concentrations of the drug. MIS (0.5 mM) alone achieved a radiosensitization enhancement ratio of 1.29 (compared to irradiated hypoxic cells alone), while the addition of the short-term heat pulse, which had only a minor effect itself, achieved an enhancement ratio of 1.78

  17. Standard sub-thermoneutral caging temperature influences radiosensitivity of hematopoietic stem and progenitor cells.

    Directory of Open Access Journals (Sweden)

    Benjamin J Povinelli

    Full Text Available The production of new blood cells relies on a hierarchical network of hematopoietic stem and progenitor cells (HSPCs. To maintain lifelong hematopoiesis, HSPCs must be protected from ionizing radiation or other cytotoxic agents. For many years, murine models have been a valuable source of information regarding factors that either enhance or reduce the survival of HSPCs after exposure of marrow to ionizing radiation. In a recent series of studies, however, it has become clear that housing-related factors such as the cool room temperature required for laboratory mice can exert a surprising influence on the outcome of experiments. Here we report that the mild, but chronic cold-stress endured by mice housed under these conditions exerts a protective effect on HSPCs after both non-lethal and lethal doses of total body irradiation (TBI. Alleviation of this cold-stress by housing mice at a thermoneutral temperature (30°C resulted in significantly greater baseline radiosensitivity to a lethal dose of TBI with more HSPCs from mice housed at thermoneutral temperature undergoing apoptosis following non-lethal TBI. Cold-stressed mice have elevated levels of norepinephrine, a key molecule of the sympathetic nervous system that binds to β-adrenergic receptors. We show that blocking this signaling pathway in vivo through use of the β-blocker propanolol completely mitigates the protective effect of cold-stress on HSPC apoptosis. Collectively this study demonstrates that chronic stress endured by the standard housing conditions of laboratory mice increases the resistance of HSPCs to TBI-induced apoptosis through a mechanism that depends upon β-adrenergic signaling. Since β-blockers are commonly prescribed to a wide variety of patients, this information could be important when predicting the clinical impact of HSPC sensitivity to TBI.

  18. AZD5438, an Inhibitor of Cdk1, 2, and 9, Enhances the Radiosensitivity of Non-Small Cell Lung Carcinoma Cells

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    Raghavan, Pavithra; Tumati, Vasu; Yu Lan [Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas (United States); Chan, Norman [Departments of Medical Biophysics and Radiation Oncology, Princess Margaret Hospital, University Health Network, University of Toronto, Ontario (Canada); Tomimatsu, Nozomi [Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas (United States); Burma, Sandeep [Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas (United States); Simmons Comprehensive Cancer Center, Dallas, Texas (United States); Bristow, Robert G. [Departments of Medical Biophysics and Radiation Oncology, Princess Margaret Hospital, University Health Network, University of Toronto, Ontario (Canada); Saha, Debabrata, E-mail: debabrata.saha@utsouthwestern.edu [Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas (United States); Simmons Comprehensive Cancer Center, Dallas, Texas (United States)

    2012-11-15

    Purpose: Radiation therapy (RT) is one of the primary modalities for treatment of non-small cell lung cancer (NSCLC). However, due to the intrinsic radiation resistance of these tumors, many patients experience RT failure, which leads to considerable tumor progression including regional lymph node and distant metastasis. This preclinical study evaluated the efficacy of a new-generation cyclin-dependent kinase (Cdk) inhibitor, AZD5438, as a radiosensitizer in several NSCLC models that are specifically resistant to conventional fractionated RT. Methods and Materials: The combined effect of ionizing radiation and AZD5438, a highly specific inhibitor of Cdk1, 2, and 9, was determined in vitro by surviving fraction, cell cycle distribution, apoptosis, DNA double-strand break (DSB) repair, and homologous recombination (HR) assays in 3 NSCLC cell lines (A549, H1299, and H460). For in vivo studies, human xenograft animal models in athymic nude mice were used. Results: Treatment of NSCLC cells with AZD5438 significantly augmented cellular radiosensitivity (dose enhancement ratio rangeing from 1.4 to 1.75). The degree of radiosensitization by AZD5438 was greater in radioresistant cell lines (A549 and H1299). Radiosensitivity was enhanced specifically through inhibition of Cdk1, prolonged G{sub 2}-M arrest, inhibition of HR, delayed DNA DSB repair, and increased apoptosis. Combined treatment with AZD5438 and irradiation also enhanced tumor growth delay, with an enhancement factor ranging from 1.2-1.7. Conclusions: This study supports the evaluation of newer generation Cdk inhibitors, such as AZD5438, as potent radiosensitizers in NSCLC models, especially in tumors that demonstrate variable intrinsic radiation responses.

  19. AZD5438, an Inhibitor of Cdk1, 2, and 9, Enhances the Radiosensitivity of Non-Small Cell Lung Carcinoma Cells

    International Nuclear Information System (INIS)

    Purpose: Radiation therapy (RT) is one of the primary modalities for treatment of non-small cell lung cancer (NSCLC). However, due to the intrinsic radiation resistance of these tumors, many patients experience RT failure, which leads to considerable tumor progression including regional lymph node and distant metastasis. This preclinical study evaluated the efficacy of a new-generation cyclin-dependent kinase (Cdk) inhibitor, AZD5438, as a radiosensitizer in several NSCLC models that are specifically resistant to conventional fractionated RT. Methods and Materials: The combined effect of ionizing radiation and AZD5438, a highly specific inhibitor of Cdk1, 2, and 9, was determined in vitro by surviving fraction, cell cycle distribution, apoptosis, DNA double-strand break (DSB) repair, and homologous recombination (HR) assays in 3 NSCLC cell lines (A549, H1299, and H460). For in vivo studies, human xenograft animal models in athymic nude mice were used. Results: Treatment of NSCLC cells with AZD5438 significantly augmented cellular radiosensitivity (dose enhancement ratio rangeing from 1.4 to 1.75). The degree of radiosensitization by AZD5438 was greater in radioresistant cell lines (A549 and H1299). Radiosensitivity was enhanced specifically through inhibition of Cdk1, prolonged G2-M arrest, inhibition of HR, delayed DNA DSB repair, and increased apoptosis. Combined treatment with AZD5438 and irradiation also enhanced tumor growth delay, with an enhancement factor ranging from 1.2-1.7. Conclusions: This study supports the evaluation of newer generation Cdk inhibitors, such as AZD5438, as potent radiosensitizers in NSCLC models, especially in tumors that demonstrate variable intrinsic radiation responses.

  20. Radio-sensitivities and angiogenic signaling pathways of irradiated normal endothelial cells derived from diverse human organs

    International Nuclear Information System (INIS)

    The purpose of the present investigation was to study the effects of ionizing radiation on endothelial cells derived from diverse normal tissues. We first compared the effects of radiation on clonogenic survival and tube formation of endothelial cells, and then investigated the molecular signaling pathways involved in endothelial cell survival and angiogenesis. Among the different endothelial cells studied, human hepatic sinusoidal endothelial cells (HHSECs) were the most radio-resistant and human dermal microvascular endothelial cells were the most radio-sensitive. The radio-resistance of HHSECs was related to adenosine monophosphate-activated protein kinase and p38 mitogen-activated protein kinase-mediated expression of MMP-2 and vascular endothelial growth factor receptor-2 (VEGFR-2), whereas the increased radio-sensitivity of HDMECs was related to extracellular signal-regulated kina0se-mediated generation of angiostatin. These observations demonstrate that there are distinct differences in the radiation responses of normal endothelial cells obtained from diverse organs, which may provide important clues for protection of normal tissue from radiation exposure. (author)

  1. Radiosensitivity of glial progenitor cells of the perinatal and adult rat optic nerve studied by an in vitro clonogenic assay

    International Nuclear Information System (INIS)

    The cellular basis of radiation-induced demyelination and white matter necrosis of the central nervous system (CNS), is poorly understood. Glial cells responsible for myelination in the CNS might be the target cells of this type of damage. Glial cells with stem cell properties derived from the perinatal and adult rat CNS can be cultured in vitro. These cells are able to differentiate into oligodendrocytes or type-2 astrocytes (O-2A) depending on the culture conditions. Growth factors produced by monolayers of type-1 astrocytes inhibit premature differentiation of O-2A progenitor cells and allow colony formation. A method which employs these monolayers of type-1 astrocytes to culture O-2A progenitor cells has been adapted to allow the analysis of colonies of surviving cells after X-irradiation. In vitro survival curves were obtained for glial progenitor cells derived from perinatal and adult optic nerves. The intrinsic radiosensitivity of perinatal and adult O-2A progenitor cells showed a large difference. Perinatal O-2A progenitor cells are quite radiosensitive, in contrast to adult O-2A progenitor cells. For both cell types an inverse relationship was found between the dose and the size of colonies derived from surviving cells. Surviving O-2A progenitor cells maintain their ability to differentiate into oligo-dendrocytes or type-2 astrocytes. This system to assess radiation-induced damage to glial progenitor cells in vitro systems to have a great potential in unraveling the cellular basis of radiation-induced demyelinating syndromes of the CNS. (author). 28 refs.; 4 figs.; 1 tab

  2. Effect of N-Ras by RNA interference on radiosensitivity of hepatoma carcinoma cell MHCC97-H line

    International Nuclear Information System (INIS)

    Objective: To investigate the radiosensitivity of silencing N-Ras by RNA interference in hepatoma carcinoma cell MHCC-97. Methods: N-Ras RNA interference (RNAi) vector was constructed by using pcDNA 6.2-GW/EmGFP-mir plamid. The RNAi effect was detected by RT-PCR, Western bolt, immunohistochemistry and MTT method. Survival curve for each cell line were obtained by measuring the clone forming abilities of irradiated cell populations. Results: After silencing the N-Ras by RNAi. The expression level of N-Ras mRNA, N-Ras protein, immunohistochemistry were decreased 96.9% ±0.159% (t=40.377, P<0.05), 89.8%±0.012% (t=31.595, P<0.05), 90%, respectively, and The survival of hepatoma carcinoma cell MHCC-97 line were inhibited 21.9% (F = 4.63, P<0.05). Which have significant difference in statistics. The SER of hepatoma carcinoma cell MHCC-97 line after interference was 1.15. Conclusions: RNAi targeting silence N-Ras may increase the radiosensitivity of hepatoma carcinoma cell MHCC-97 line. (authors)

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

    International Nuclear Information System (INIS)

    Hypoxia-inducible factor-1 (HIF-1) overexpression has been linked to tumor progression and poor prognosis. We investigated whether targeting of HIF-1 using chetomin, a disrupter of the interaction of HIF-1 with the transcriptional coactivator p300, influences the radiosensitivity of hypoxic HT 1080 human fibrosarcoma cells. Optimal dose of chetomin was determined by EGFP-HRE gene reporter assay in stably transfected HT 1080 cells. Cells were assayed for expression of the hypoxia-inducible genes carbonic anhydrase 9 (CA9) and vascular endothelial growth factor (VEGF) by RT-PCR and for clonogenic survival after irradiation with 2, 5 or 10 Gy, under normoxic or hypoxic (0.1% O2, 12 h) conditions in the presence or absence of chetomin (150 nM, 12 h, pre-treatment of 4 h). Chetomin treatment significantly reduced CA9 and VEGF mRNA expression in hypoxic cells to 44.4 ± 7.2% and 39.6 ± 16.0%, respectively, of untreated hypoxic controls. Chetomin clearly reduced the modified oxygen enhancement ratio (OER') compared to untreated cells, from 2.02 to 1.27, from 1.86 to 1.22 and from 1.49 to 1.06 at the 50%, 37% and 10% clonogenic survival levels, respectively. HIF-1 inhibition by chetomin effectively reduces hypoxia-dependent transcription and radiosensitizes hypoxic HT 1080 human fibrosarcoma cells in vitro

  4. Resveratrol-Induced Apoptosis and Increased Radiosensitivity in CD133-Positive Cells Derived From Atypical Teratoid/Rhabdoid Tumor

    International Nuclear Information System (INIS)

    Purpose: CD133 has recently been proposed as a marker for cancer stem-like cells (CSC) in brain tumors. The aim of the present study was to investigate the possible role of resveratrol (RV) in radiosensitivity of CD133-positive/-negative cells derived from atypical teratoid/rhabdoid tumors (AT/RT-CD133+/-). Materials and Methods: AT/RT-CD133+/- were isolated and characterized by flow cytometry and quantitative real-time reverse transcription-polymerase chain reaction, and then treated with RV at different doses. Migratory ability, colony formation, apoptotic activity, and xenotransplantation were assessed for RV alone, ionizing radiation (IR) alone, and IR with RV conditions. Results: AT/RT-CD133+ displayed enhanced self-renewal and highly coexpressed 'stem cell' genes and drug-resistant genes, in addition to showing significant resistance to chemotherapeutic agents and radiotherapy as compared with CD133- cells. After treatment with 200 μM RV, the in vitro proliferation rates and in vivo tumor restoration abilities of ATRT-CD133+ were dramatically inhibited. Importantly, treatment with 150 μM RV can effectively inhibit the expression of drug-resistant genes in AT/RT-CD133+, and further facilitate to the differentiation of CD133+ into CD133-. In addition, treatment with 150 μM RV could significantly enhance the radiosensitivity and IR-mediated apoptosis in RV-treated ATRT-CD133+/-. Kaplan-Meier survival analysis indicated that the mean survival rate of mice with ATRT-CD133+ that were treated with IR could be significantly improved when IR was combined with 150 μM RV treatment. Conclusions: AT/RT-CD133+ exhibit CSC properties and are refractory to IR treatment. Our results suggest that RV treatment plays crucial roles in antiproliferative, proapoptotic, and radiosensitizing effects on treated-CD133+/-; RV may therefore improve the clinical treatment of AT/RT.

  5. Radiosensitivity - a genotype dependent mechanism

    International Nuclear Information System (INIS)

    For determining relative radiosensitivity, bulbs of 3 different sizes of Allium cepa L. having same cell size, chromosome number, ICV, INV and DNA content were exposed to different doses of gamma-rays. Gamma ray induced chromosomal aberrations as the end point of radiosensitivity was studied in root meristem and it was found that the aberration percentage increased with increase in doses in all cases. The medium size was found to be much sensitive indicating genotype dependent mechanism for radiosensitivity. (author). 34 refs., 3 tabs

  6. In vitro effects of piracetam on the radiosensitivity of hypoxic cells (adaptation of MTT assay to hypoxic conditions)

    International Nuclear Information System (INIS)

    This paper describes the adaptation of the MTT assay to hypoxic conditions in order to test the in vitro effect of piracetam on hypoxic cells and particularly on the radiosensitivity of hypoxic cells since this drug has shown clinical effect on acute and chronic hypoxia. The V79 cell line was selected by reference to preliminary hypoxic experiments using clonogenic assay and euoxic experiments using clonogenic and MTT assays. Cell growth and survival in our hypoxic conditions were assessed using MTT assay with an enclosure and special 48-well plates both made of glass. Growth curves on glass plates after 1-hour exposure to nitrogen versus air were comparable, so there is no bias effect due to gas composition. Survival curves using MTT versus reference clonogenic assay were comparable after radiation exposure in eu- and hypoxic conditions, and confirm the validity of our original technique for creating hypoxia. The Oxygen Enhancement Ratio was of about 3 for 1-hour hypoxic exposure. Piracetam gave no cytotoxic effect up to 10 mM of piracetam. Growth curves after continuous drug exposure and 1-hour euoxic versus hypoxic exposure gave no cytotoxic effect up to 10 mM of piracetam. Survival curves after continuous drug exposure to 10 mM of piracetam gave no significant effect on the radiosensitivity of hypoxic V79 cells using MTT or clonogenic assay. (author). 32 refs., 6 figs

  7. Radiosensitivity of stromal cells human bone marrow precursors, irradiated in vitro inside bone and in cell suspension and a modifying effect of hypoxia

    International Nuclear Information System (INIS)

    A study was made of radiosensitivity of human bone marrow cells that form fibroblast colonies within monolayer cultures (CFUsub(f)) after exposure to 60Co-γ-radiation under different conditions: in pieces of an extirpated bone and in a cell suspension. Dose survival curves for CFUsub(f) obtained from both variants of the experiment vary merkedly in the value of median lethal dose (Dsub(O)) which constitute.s 89 rad for cell suspension and 328 rad for bone pieces. Radioresistance of CFUsub(f) increases (sub(o)=126 rad) in the suspension bubbled with argon whereas substitution of the atmosphere with argon does not influence the sensitivity of CFU irradiated in bone. The observed distinctions in radiosensitivity of human bone marrow CFU irradiated in suspension and bone pieces are probably related to different oxygen status of cells at time of irradiation. Maximum value of the oxygen effect for CFUsub(f) is 3.7

  8. Celecoxib Enhances the Radiosensitizing Effect of 7-Hydroxystaurosporine (UCN-01) in Human Lung Cancer Cell Lines

    International Nuclear Information System (INIS)

    Purpose: 7-Hydroxystaurosporine (UCN-01), a Chk1-specific inhibitor, showed promising in vitro and in vivo chemo- or radiosensitizing activity. However, there have been concerns about its limited therapeutic efficacy and risk of side effects. A method of enhancing the treatment efficacy of UCN-01 while not increasing its side effects on normal tissue may therefore be required to apply this drug in clinical settings. Celecoxib is a cyclooxygenase-2 (COX-2)-specific inhibitor that downregulates ataxia telangiectasia and rad3-related (ATR) protein, an upstream kinase of Chk1. In this study, we investigated whether the addition of celecoxib can potentiate the radiosensitizing effect of UCN-01. Methods and Materials: The cooperative radiosensitizing effects and the underlying molecular mechanisms of UCN-01 plus celecoxib were determined by clonogenic assay, tumor growth delay assay, flow cytometry, and Western blotting. Synergism of the three agents combined (UCN-01 plus celecoxib plus radiation) were evaluated using median drug effect analysis and drug-independent action model analysis. Results: The combination of UCN-01 and celecoxib could induce synergistic cytotoxicity and radiosensitizing effects in in vitro and in vivo systems. The combination of both drugs also cooperatively inhibited IR-induced G2/M arrest, and increased the G2 to mitotic transition. Conclusions: Combined treatment with UCN-01 and celecoxib can exert synergistically enhanced radiosensitizing effects via cooperative inhibition of the ionizing radiation-activated G2 checkpoint. We propose that this combination strategy may be useful in clinical applications of UCN-01 for radiotherapy of cancer patients.

  9. Celecoxib Enhances the Radiosensitizing Effect of 7-Hydroxystaurosporine (UCN-01) in Human Lung Cancer Cell Lines

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young-Mee; Jeong, In-Hye [Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Pyo, Hongryull, E-mail: Quasar93@yahoo.co.kr [Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

    2012-07-01

    Purpose: 7-Hydroxystaurosporine (UCN-01), a Chk1-specific inhibitor, showed promising in vitro and in vivo chemo- or radiosensitizing activity. However, there have been concerns about its limited therapeutic efficacy and risk of side effects. A method of enhancing the treatment efficacy of UCN-01 while not increasing its side effects on normal tissue may therefore be required to apply this drug in clinical settings. Celecoxib is a cyclooxygenase-2 (COX-2)-specific inhibitor that downregulates ataxia telangiectasia and rad3-related (ATR) protein, an upstream kinase of Chk1. In this study, we investigated whether the addition of celecoxib can potentiate the radiosensitizing effect of UCN-01. Methods and Materials: The cooperative radiosensitizing effects and the underlying molecular mechanisms of UCN-01 plus celecoxib were determined by clonogenic assay, tumor growth delay assay, flow cytometry, and Western blotting. Synergism of the three agents combined (UCN-01 plus celecoxib plus radiation) were evaluated using median drug effect analysis and drug-independent action model analysis. Results: The combination of UCN-01 and celecoxib could induce synergistic cytotoxicity and radiosensitizing effects in in vitro and in vivo systems. The combination of both drugs also cooperatively inhibited IR-induced G{sub 2}/M arrest, and increased the G{sub 2} to mitotic transition. Conclusions: Combined treatment with UCN-01 and celecoxib can exert synergistically enhanced radiosensitizing effects via cooperative inhibition of the ionizing radiation-activated G{sub 2} checkpoint. We propose that this combination strategy may be useful in clinical applications of UCN-01 for radiotherapy of cancer patients.

  10. Mechanism of the radiosensitizing effect of low dose ionizing radiation in the HeLa cell culture

    International Nuclear Information System (INIS)

    The sensitizing effect of preliminary irradiation (10 R) 2-3 min prior to applying the main dose of 490 R was studied on a HeLa cell culture. The overall dose, divided in this manner, was found to initially have the same stimulative effect as 10 R. The inhibitory action of the main dose showed only after 1.5-2.0 hr. The results on the radiosensitizing effect of preliminary irradiation with 10 R might be explained by the delayed action of a complex of adaptive responses. An examination of the dosage curve showed preliminary irradiation with 10 R to cause a decline in reparation processes

  11. 5-fluorouracil (5-FU) enhances radiosensitivity of the human pancreatic cancer cell line mia PaCa-2

    International Nuclear Information System (INIS)

    Several studies have suggested that the combination of radiation therapy and 5-FU may improve local control and survival of patients with pancreatic cancer. However, the optimal timing and regimens (pulse vs continuous infusion) of 5-FU have not been clearly defined yet. The purpose is to assess the effect of different administration schedules of 5-FU on the radiosensitivity of human pancreatic tumour cells. These results give experimental support to the association of radiotherapy and 5-FU in pancreatic cancer treatment and suggest that continuous 5-FU infusion could be more effective than pulse administration. (authors)

  12. Azomycin riboside: a new radiosensitizer

    International Nuclear Information System (INIS)

    Azomycin riboside (2-nitro-1-β-D-ribofuranosylimidazole) (AR), a nucleoside analogue with the base component replaced by a 2-nitroimidazole was studied to determine its potential as a radiosensitizer. In vitro evidence showed that AR is as good as or slightly better than misonidazole (MISO) as a hypoxic cell radiosensitizer. AR was also found to kill hypoxic cells directly and this cytotoxicity was at least as great as MISO cytotoxicity. However, when tumor regrowth delay was used to assess in vivo radiosensitization, AR was found to be inferior to MISO while the LD50 host toxicity assay indicated that AR might be nearly as toxic as MISO. Unless AR proves to be less toxic than MISO or can be selectively distributed with nucleoside transport inhibitors, these preliminary observations have not shown any advantage of AR over MISO as a potential clinically useful radiosensitizer

  13. The combination effect of sodium butyrate and 5-Aza-2'-deoxycytidine on radiosensitivity in RKO colorectal cancer and MCF-7 breast cancer cell lines

    Directory of Open Access Journals (Sweden)

    Oh Seong

    2009-05-01

    Full Text Available Abstract Background The overall level of chromatin compaction is an important mechanism of radiosensitivity, and modification of DNA methylation and histone deacetylation may increase radiosensitivity by altering chromatin compaction. In this study, we investigated the effect of a demethylating agent, a histone deacetylase(HDAC inhibitor, and the two agents combined on radiosensitivity in human colon and breast cancer cell lines. Methods In this study, we used RKO colorectal cancer cell line and MCF-7 breast cancer cell lines and normal colon cell lines. On each of the cell lines, we used three different agents: the HDAC inhibitor sodium butyrate(SB, the demethylating agent 5-Aza-2'-deoxycytidine(5-aza-DC, and radiation. We then estimated the percentage of the cell survival using the XTT method and experimented to determine if there was an augmentation in the therapeutic effect by using different combinations of the two or three of the treatment methods. Results After treatment of each cell lines with 5-aza-DC, SB and 6 grays of radiation, we observed that the survival fraction was lower after the treatment with 5-aza-DC or SB than with radiation alone in RKO and MCF-7 cell lines(p Conclusion In conclusion, 5-aza-DC and SB can enhance radiosensitivity in both MCF-7 and RKO cell lines. The combination effect of a demethylating agent and an HDAC inhibitor is more effective than that of single agent treatment in both breast and colon cancer cell lines.

  14. Preclinical Evaluation of Genexol-PM, a Nanoparticle Formulation of Paclitaxel, as a Novel Radiosensitizer for the Treatment of Non-Small Cell Lung Cancer

    International Nuclear Information System (INIS)

    Purpose: A key research objective in radiation oncology is to identify agents that can improve chemoradiation therapy. Nanoparticle (NP) chemotherapeutics possess several properties, such as preferential accumulation in tumors, that are uniquely suited for chemoradiation therapy. To facilitate the clinical translation of NP chemotherapeutics in chemoradiation therapy, we conducted preclinical evaluation of Genexol-PM, the only clinically approved NP chemotherapeutic with a controlled drug release profile, as a radiosensitizer using non-small cell lung cancer (NSCLC) as a model disease. Methods and Materials: The physical characteristics and drug release profile of Genexol-PM were characterized. Genexol-PM's efficacy as a radiosensitizer was evaluated in vitro using NSCLC cell lines and in vivo using mouse xenograft models of NSCLC. Paclitaxel dose to normal lung and liver after Genexol-PM administration were quantified and compared with that after Taxol administration. Results: Genexol-PM has a size of 23.91 ± 0.41 nm and surface charge of −8.1 ± 3.1 mV. It releases paclitaxel in a controlled release profile. In vitro evaluation of Genexol-PM as a radiosensitizer showed it is an effective radiosensitizer and is more effective than Taxol, its small molecule counterpart, at the half maximal inhibitory concentration. In vivo study of Genexol-PM as a radiosensitizer demonstrated that it is more effective as a radiosensitizer than Taxol. We also found that Genexol-PM leads to lower paclitaxel exposure to normal lung tissue than Taxol at 6 hours postadministration. Conclusions: We have demonstrated that Genexol-PM is more effective than Taxol as a radiosensitizer in the preclinical setting and holds high potential for clinical translation. Our data support the clinical evaluation of Genexol-PM in chemoradiation therapy for NSCLC

  15. Preclinical Evaluation of Genexol-PM, a Nanoparticle Formulation of Paclitaxel, as a Novel Radiosensitizer for the Treatment of Non-Small Cell Lung Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Werner, Michael E.; Cummings, Natalie D.; Sethi, Manish; Wang, Edina C.; Sukumar, Rohit [Laboratory of Nano- and Translational Medicine, Department of Radiation Oncology, Lineberger Comprehensive Cancer Center, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina (United States); Carolina Center for Cancer Nanotechnology Excellence, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina (United States); Moore, Dominic T. [Division of Biostatistics and Data Management, Lineberger Comprehensive Cancer Center, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina (United States); Wang, Andrew Z., E-mail: zawang@med.unc.edu [Laboratory of Nano- and Translational Medicine, Department of Radiation Oncology, Lineberger Comprehensive Cancer Center, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina (United States); Carolina Center for Cancer Nanotechnology Excellence, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina (United States)

    2013-07-01

    Purpose: A key research objective in radiation oncology is to identify agents that can improve chemoradiation therapy. Nanoparticle (NP) chemotherapeutics possess several properties, such as preferential accumulation in tumors, that are uniquely suited for chemoradiation therapy. To facilitate the clinical translation of NP chemotherapeutics in chemoradiation therapy, we conducted preclinical evaluation of Genexol-PM, the only clinically approved NP chemotherapeutic with a controlled drug release profile, as a radiosensitizer using non-small cell lung cancer (NSCLC) as a model disease. Methods and Materials: The physical characteristics and drug release profile of Genexol-PM were characterized. Genexol-PM's efficacy as a radiosensitizer was evaluated in vitro using NSCLC cell lines and in vivo using mouse xenograft models of NSCLC. Paclitaxel dose to normal lung and liver after Genexol-PM administration were quantified and compared with that after Taxol administration. Results: Genexol-PM has a size of 23.91 ± 0.41 nm and surface charge of −8.1 ± 3.1 mV. It releases paclitaxel in a controlled release profile. In vitro evaluation of Genexol-PM as a radiosensitizer showed it is an effective radiosensitizer and is more effective than Taxol, its small molecule counterpart, at the half maximal inhibitory concentration. In vivo study of Genexol-PM as a radiosensitizer demonstrated that it is more effective as a radiosensitizer than Taxol. We also found that Genexol-PM leads to lower paclitaxel exposure to normal lung tissue than Taxol at 6 hours postadministration. Conclusions: We have demonstrated that Genexol-PM is more effective than Taxol as a radiosensitizer in the preclinical setting and holds high potential for clinical translation. Our data support the clinical evaluation of Genexol-PM in chemoradiation therapy for NSCLC.

  16. Premature chromosome condensation and cell separation studies in biopsies from head and neck tumors for radiosensitivity prediction

    International Nuclear Information System (INIS)

    Background and purpose: Intrinsic radiosensitivity of tumor cells from biopsies, assayed by colony formation after in vitro irradiation, has shown significant correlations with outcome after radiotherapy. Alternatives to the colony assay have been sought due to its long and cumbersome nature. We have previously shown good correlations between colony formation and radiation-induced chromosome aberrations in human tumor cell lines. In addition, we and others have shown on cell lines that premature chromosome condensation (PCC) induced with phosphatase inhibitors can be used to aid rapid assessment of aberrations in interphase cells, reducing the selection problem with metaphases. The purpose of this study was to translate the in vitro results to human cancer, with the aim of developing a rapid assay for intrinsic radiosensitivity. Methods and results: The problem of admixtures of normal and malignant cells in biopsies was addressed using magnetic bead separation (MACS) employing antibodies to human fibroblasts. This proved to be a reliable and efficient method, enriching mean tumor cell fractions from 20 to almost 80%. PCC could be induced in human normal and tumor cell lines, and in sorted or unsorted suspensions from biopsies, with the phosphatase inhibitor calyculin A. Maximum PCCs were achieved after 1-week culture of biopsy-derived cells. Mean fractions of aneuploid tumor cell PCCs were, however, less than 1%. PCCs were predominantly from S and G2 phase, of which only G2 were scorable for aberrations. Almost no G1 PCCs were found. More scorable PCCs were found after 1 h of calyculin A than metaphases after 5 h of colcemid, but these were calculated to be too few to yield reliable estimates of chromosome damage after radiation. Conlcusions: Tumor cells can be satisfactorily separated from fibroblasts in fresh suspensions from cancer biopsies, but poor growth of tumor cells in short term culture and low yields of PCCs combine to prevent the routine use of such

  17. Radiosensitivity of bone narrow cells and some estimates of postirradiation myelopoiesis kinetics (analysis of Chernobyl disaster consequences)

    International Nuclear Information System (INIS)

    On the basis of the data obtained from 61 cases of accidental exposure (0.1-12.5 Gy) at the Chernobyl A.P.S. the kinetics of acute radiation bone-marrow syndrome was analyzed and radiosensitivity of the entire spectrum of human granulocytic compartment cells was estimated. Changes were found in physiology of myeloid cells during their maturation: the maturation mechanism, for cells of the committed pool, was attached to the division process, whereas these processes were independent for cells of the dividing and maturing pool. It is once again confirmed that the transit time of a maturing myeloid cell, to begin with the primarily committed one and to end with a peripheral blood neutrophil, is not constant and lasts normally for 32 days

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

    Directory of Open Access Journals (Sweden)

    Wenbo Wang

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

  19. Radiosensitization dependent on p53 function in bronchial carcinoma cells by the isoflavone genistein and estradiol in vitro

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    Hermann, R.M.; Fest, J.; Christiansen, H.; Hille, A.; Rave-Fraenk, M.; Nitsche, M. [Goettingen Univ. (Germany). Dept. of Radiotherapy and Radiooncology; Gruendker, C.; Viereck, V. [Goettingen Univ. (Germany). Dept. of Gynecology; Jarry, H. [Goettingen Univ. (Germany). Dept. of Experimental Endocrinology; Schmidberger, H. [University Hospital Mainz (Germany). Dept. of Radiooncology and Radiotherapy

    2007-04-15

    Background and Purpose: Simultaneous radiotherapy with chemotherapy is a standard treatment for inoperable non-small cell lung cancer (NSCLC), but the clinical outcome still remains poor. To further intensify treatment, substances need to be identified, which increase the effect of radiation on tumor cells without further enhancing toxicity to normal tissue. Hormones have a different toxicity profile than radiation or cytostatic drugs. As NSCLC often express estrogen receptors (ERs), the combination of genistein or estradiol and radiation in vitro was investigated. Material and Methods: A549 NSCLC cells with an inducible expression of a mutated TP53 and fibroblasts of a male donor (DF-18) were examined. ER expression was immunocytologically confirmed in all studied cell lines. Clonogenic survival was measured after incubation of the cells with genistein or estradiol (0.01 {mu}M and 10 {mu}M as maximum clinically applicable dose) and irradiation with different doses (0-4 Gy). The differentiation state of fibroblasts after combined therapy was analyzed. Results: A549 cells expressing mutated TP53 were more radioresistant than TP53 wild-type cells. Incubation of nonfunctional TP53 cells with genistein or estradiol increased radiosensitivity in both tested concentrations. By contrast, radiosensitivity of A549 with wild-type TP53 and DF-18 was not altered by hormonal incubation. In DF-18 radiation induced growth arrest that was not increased by additional hormonal incubation. Conclusion: NSCLC cells with nonfunctional TP53 might be sensitized against radiation by genistein or estradiol. As genistein is better tolerable than estradiol in patients, additional studies are warranted to assess potential gains of this combination therapy.

  20. Radiosensitizing effect of conjugated linoleic acid in MCF-7 and MDA-MB-231 breast cancer cells

    International Nuclear Information System (INIS)

    Apoptotic pathways in breast cancer cells are frequently altered, reducing the efficiency of radiotherapy. Conjugated linoleic acid (CLA), known to trigger apoptosis, was tested as radiosensitizer in breast cancer cells MCF-7 and MDA-MB-231. The CLA-mix, made up of the isomers CLA-9cis 11trans and CLA-10trans 12cis, was compared to three purified isomers, i.e., the CLA-9cis 11cis, CLA-9cis 11trans, and CLA-10trans 12cis. Using the apoptotic marker YO-PRO-1, the CLA-9cis 11cis at 50 μmol/L turned out to be the best apoptotic inducer leading to a 10-fold increase in MCF-7 cells and a 2,5-fold increase in MDA-MB-231 cells, comparatively to the CLA-mix. Contrary to previous studies on colorectal and prostate cancer cells, CLA-10trans 12cis does not lead to an apoptotic response on breast cancer cell lines MCF-7 and MDA-MB-231. Our results also suggest that the main components of the CLA-mix (CLA-9cis 11trans and CLA-10trans 12cis) are not involved in the induction of apoptosis in the breast cancer cells studied. A dose of 5 Gy did not induce apoptosis in MCF-7 and MDA-MB-231 cells. The addition of CLA-9cis 11cis or CLA-mix has allowed us to observe a radiation-induced apoptosis, with the CLA-9cis 11cis being about 8-fold better than the CLA-mix. CLA-9cis 11cis turned out to be the best radiosensitizer, although the isomers CLA-9cis 11trans and CLA-10trans 12cis have also reduced the cell survival following irradiation, but using a mechanism not related to apoptosis. In conclusion, the radiosensitizing property of CLA-9cis 11cis supports its potential as an agent to improve radiotherapy against breast carcinoma. (author)

  1. Molecular basis of ‘hypoxic’ breast cancer cell radio-sensitization: phytochemicals converge on radiation induced Rel signaling

    International Nuclear Information System (INIS)

    Heterogeneously distributed hypoxic areas are a characteristic property of locally advanced breast cancers (BCa) and generally associated with therapeutic resistance, metastases, and poor patient survival. About 50% of locally advanced BCa, where radiotherapy is less effective are suggested to be due to hypoxic regions. In this study, we investigated the potential of bioactive phytochemicals in radio-sensitizing hypoxic BCa cells. Hypoxic (O2-2.5%; N2-92.5%; CO2-5%) MCF-7 cells were exposed to 4 Gy radiation (IR) alone or after pretreatment with Curcumin (CUR), curcumin analog EF24, neem leaf extract (NLE), Genistein (GEN), Resveratrol (RES) or raspberry extract (RSE). The cells were examined for inhibition of NFκB activity, transcriptional modulation of 88 NFκB signaling pathway genes, activation and cellular localization of radio-responsive NFκB related mediators, eNos, Erk1/2, SOD2, Akt1/2/3, p50, p65, pIκBα, TNFα, Birc-1, -2, -5 and associated induction of cell death. EMSA revealed that cells exposed to phytochemicals showed complete suppression of IR-induced NFκB. Relatively, cells exposed EF24 revealed a robust inhibition of IR-induced NFκB. QPCR profiling showed induced expression of 53 NFκB signaling pathway genes after IR. Conversely, 53, 50, 53, 53, 53 and 53 of IR-induced genes were inhibited with EF24, NLE, CUR, GEN, RES and RSE respectively. In addition, 25, 29, 24, 16, 11 and 21 of 35 IR-suppressed genes were further inhibited with EF24, NLE, CUR, GEN, RES and RSE respectively. Immunoblotting revealed a significant attenuating effect of IR-modulated radio-responsive eNos, Erk1/2, SOD2, Akt1/2/3, p50, p65, pIκBα, TNFα, Birc-1, -2 and −5 with EF24, NLE, CUR, GEN, RES or RSE. Annexin V-FITC staining showed a consistent and significant induction of IR-induced cell death with these phytochemicals. Notably, EF24 robustly conferred IR-induced cell death. Together, these data identifies the potential hypoxic cell radio-sensitizers and further

  2. ZnFe{sub 2}O{sub 4} nanoparticles as radiosensitizers in radiotherapy of human prostate cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Meidanchi, Alireza [Department of Physics, Payame Noor University (PNU), P.O. Box 19395-3697, Tehran (Iran, Islamic Republic of); Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of); Akhavan, Omid, E-mail: oakhavan@sharif.edu [Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of); Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 14588-89694, Tehran (Iran, Islamic Republic of); Khoei, Samideh [Department of Medical Physics, Iran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Shokri, Ali A. [Department of Physics, Payame Noor University (PNU), P.O. Box 19395-3697, Tehran (Iran, Islamic Republic of); Computational Physical Sciences Research Laboratory, School of Nano-Science, Institute for Studies in Theoretical Physics and Mathematics (IPM), PO Box 19395-5531, Tehran (Iran, Islamic Republic of); Hajikarimi, Zahra [Department of Medical Physics, Iran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Khansari, Nakisa [Department of Cardiology, Hamadan University of Medical Sciences, Hamadan (Iran, Islamic Republic of)

    2015-01-01

    Nanoparticles of high-Z elements exhibit stronger photoelectric effects than soft tissues under gamma irradiation. Hence, they can be used as effective radiosensitizers for increasing the efficiency of current radiotherapy. In this work, superparamagnetic zinc ferrite spinel (ZnFe{sub 2}O{sub 4}) nanoparticles were synthesized by a hydrothermal reaction method and used as radiosensitizers in cancer therapy. The magnetic nanoparticles showed fast separation from solutions (e.g., ∼ 1 min for 2 mg mL{sup −1} of the nanoparticles in ethanol) by applying an external magnetic field (∼ 1 T). The ZnFe{sub 2}O{sub 4} nanoparticles were applied in an in vitro radiotherapy of lymph node carcinoma of prostate cells (as high radioresistant cells) under gamma irradiation of {sup 60}Co source. The nanoparticles exhibited no significant effects on the cancer cells up to the high concentration of 100 μg mL{sup −1}, in the absence of gamma irradiation. The gamma irradiation alone (2 Gy dose) also showed no significant effects on the cells. However, gamma irradiation in the presence of 100 μg mL{sup −1} ZnFe{sub 2}O{sub 4} nanoparticles resulted in ∼ 53% inactivation of the cells (∼ 17 times higher than the inactivation that occurred under gamma irradiation alone) after 24 h. The higher cell inactivation was assigned to interaction of gamma radiation with nanoparticles (photoelectric effect), resulting in a high level electron release in the media of the radioresistant cells. Our results indicated that ZnFe{sub 2}O{sub 4} nanoparticles not only can be applied in increasing the efficiency of radiotherapy, but also can be easily separated from the cell environment by using an external magnetic field after the radiotherapy. - Highlights: • Synthesis of magnetic ZnFe{sub 2}O{sub 4} nanoparticles with high-Z elements as radiosensitizers • Fast separation of the nanoparticles from solutions by applying a magnetic field • Application of the nanoparticles in efficient

  3. AG825对乳腺癌细胞的辐射增敏作用%AG825 increases radiosensitivity of breast cancer cell

    Institute of Scientific and Technical Information of China (English)

    Bo Luo; Shiying Yu; Liang Zhuang; Shu Xia; Zhen Zhao; Lei Rong

    2008-01-01

    Objective: To observe the radiosensitivity effect of AG825 on breast cancer cell line with high expression of ERBB2 in vitro. Methods: MTT and clone formation assay were used to observe the effect of AG825 on proliferation and radiosensitivity of breast cancer line MDA-MB-453. After MDA-MB-453 was exposed to AG825 and radiation, comet assay and Western blotting were applied to detect double strand break and expressions DNA-PKcs protein, respectively. Results: AG825 inhibited proliferation rate and decrease survival fraction of MDA-MB-453. After radiation, compared with control group, expression of DNA-PKcs was lower in group with AG825 presence but double strand break was higher. Conclusion: AG825 could increase radiosensitivity of breast cancer cell line MDA-MB-453, and it may associate with its inhibition of radiation induced expression of DNA-PKcs and double strand break repair.

  4. The study on the mechanism of enhanced radio-sensitivity of glioma cell U251 by thalidomide

    International Nuclear Information System (INIS)

    In order to investigate the inhibition of DNA synthesis and the mechanism of thalidomide enhanced radio-sensitivity on glioma U251 cells, survival rate of the cells was assessed by MTT assay; and 3H-TdR incorporation assay was used to investigate the inhibition of DNA synthesis by thalidomide alone and combined with X-rays; VEGF mRNA expressions were evaluated using RT-PCR assay. Protein expression (VEGF) was detected by Western blot analysis. Thalidomide inhibited DNA synthesis depending on the concentration of thalidomide and radiation dose. Thalidomide markedly down-regulated VEGF mRNA combined with X-rays in which a synergistic action appeared. Low dose X-rays can induce VEGF protein expression in 24 h. Thalidomide was a low toxicity to U251 cells. Thalidomide inhibited DNA synthesis of U251 cells. (authors)

  5. Comparison of the chromosomal radiosensitivity of blood lymphocytes and stem-cell spermatogonia in the rhesus monkey and the mouse

    International Nuclear Information System (INIS)

    By experiments similar to those with the mouse we studied, in the rhesus monkey (Macaca mulatta), the induction by X-rays of reciprocal translocations in steam-cell spermatogonia and of dicentric chromosomes in blood lymphocytes. Human blood lymphocytes and rhesus monkey lymphocytes showed about equal sensitivity to dicentric induction. This equal radiosensitivity of somatic cells, however, provides no clue to the quantitative extrapolation to the human situation of the data obtained on translocation induction in stem-cell spermatogonia of the rhesus monkey. In our opinion, only direct observations on induced chromosomal aberrations in germ cells of higher primates and man can play a decisive role in estimating human genetic radiation risks arising from chromosomal aberrations. (orig./AJ)

  6. Effect of Recombinant Human Endostatin on Radiosensitivity in Patients With Non–Small-Cell Lung Cancer

    International Nuclear Information System (INIS)

    Purpose: To observe the effects of recombinant human endostatin (RHES) on the radiosensitivity of non-small cell lung cancer (NSCLC). Methods and Materials: First, 10 hypoxia-positive cases of pathology-diagnosed NSCLC selected from 15 patients were used to determine the normalization window, a period during which RHES improves NSCLC hypoxia. Second, 50 hypoxia-positive cases of pathology-diagnosed NSCLC (Stages I–III) were randomly divided into a RHES plus radiotherapy group (25 cases) and a radiotherapy-alone group (25 cases). Intensity = modulated radiotherapy with a total dose of 60 Gy in 30 fractions for 6 weeks was adopted in the two groups. The target area included primary foci and metastatic lymph nodes. In the RHES plus radiotherapy group, RHES (15 mg/day) was intravenously given during the normalization window. Results: After RHES administration, the tumor-to=normal tissue radioactivity ratio and capillary permeability surface were first decreased and then increased, with their lowest points on the fifth day compared with the first day (all p < 0.01). Blood flow was first increased and then decreased, with the highest point on the fifth day, compared with the first and tenth day (all p < 0.01). In the RHES plus radiotherapy group and the radiotherapy-alone group, the total effective rates (complete response plus partial response) were 80% and 44% (p = 0.009), respectively. The median survival times were 21.1 ± 0.97 months and 16.5 ± 0.95 months (p = 0.004), respectively. The 1-year and 2-year local control rates were 78.9 ± 8.4% and 68.1 ± 7.8% (p = 0.027) and 63.6 ± 7.2% and 43.4 ± 5.7% (p = 0.022), respectively. The 1-year and 2-year overall survival rates were 83.3 ± 7.2% and 76.6 ± 9.3% (p = 0.247) and 46.3 ± 2.4% and 37.6 ± 9.1% (p = 0.218), respectively. Conclusion: The RHES normalization window is within about 1 week after administration. RHES combined with radiotherapy within the normalization window has better short-term therapeutic

  7. Study on the radiosensitivity of nude mice model transplanted lung adenocarcinoma cell treated by β-elemene

    International Nuclear Information System (INIS)

    Objective: To explore the effect of β-element on the radiosensitivity of transplanted tumor, and its relationship with the expression of surviving. Methods: The transplanted mice model was established through the cell suspension inoculation. The mice with transplanted tumor size of 0.8-1.0 cm3 were randomly divided into 8 groups as blank control, 25, 45 and 100 mg/kg group, irradiation group, 25 mg/kg + irradiation group, 45 mg/kg + irradiation group, 100 mg/kg + irradiation group. The tumor size was measured every other day until tumor size was double, and the growth curve was obtained. The average tumor growth inhibition rate of β-element and tumor size were attained at 2, 4, 6 and 8 d after β-element injection. The expression of surviving was detected with immunohistochemistry. Results: The nude mice model was successfully established and the growth curves were obtained according to the tumor size. Between 2 and 8 d after β-elemene injection, the variation tendency of the average tumor growth inhibition rate was consistent with the size in β-elemene treatment groups. The antitumor effect of β-elemene was in a dose-dependent manner. The values of radiosensitivity enhancement factor were 0.84, 1.24, 2.04 for 25, 45 and 100 mg/kg group, respectively, and the optimal dose was 45 mg/kg. β-element had little effect on the expression of surviving, and the expression of surviving significantly enhanced in irradiation group and decreased in β-element + irradiation groups. Conclusions: β-elemene could enhance the tumor radiosensitivity through inhibition the expression of surviving. (authors)

  8. Different Mechanisms of Cell Death in Radiosensitive and Radioresistant P53 Mutated Head and Neck Squamous Cell Carcinoma Cell Lines Exposed to Carbon Ions and X-Rays

    International Nuclear Information System (INIS)

    Purpose: We initiated studies on the mechanisms of cell death in head and neck squamous cell carcinoma cell lines (HNSCC) since recent clinical trials have shown that local treatment of HNSCC by carbon hadrontherapy is less efficient than it is in other radioresistant cancers. Methods and Materials: Two p53-mutated HNSCC cell lines displaying opposite radiosensitivity were used. Different types of cell death were determined after exposure to carbon ions (33.6 and 184 keV/μm) or X-rays. Results: Exposure to radiation with high linear energy transfer (LET) induced clonogenic cell death for SCC61 (radiosensitive) and SQ20B (radioresistant) cells, the latter systematically showing less sensitivity. Activation of an early p53-independent apoptotic process occurred in SCC61 cells after both types of irradiation, which increased with time, dose and LET. In contrast, SQ20B cells underwent G2/M arrest associated with Chk1 activation and Cdc2 phosphorylation. This inhibition was transient after X-rays, compared with a more prolonged and LET-dependent accumulation after carbon irradiation. After release, a LET-dependent increase of polyploid and multinucleated cells, both typical signs of mitotic catastrophe, was identified. However, a subpopulation of SQ20B cells was able to escape mitotic catastrophe and continue to proliferate. Conclusions: High LET irradiation induced distinct types of cell death in HNSCC cell lines and showed an increased effectiveness compared with X-rays. However, the reproliferation of SQ20B may explain the potential locoregional recurrence observed among some HNSCC patients treated by hadrontherapy. An adjuvant treatment forcing the tumor cells to enter apoptosis may therefore be necessary to improve the outcome of radiotherapy.

  9. Radiosensitivity of amphibia

    International Nuclear Information System (INIS)

    Radiosensitivity (semi-lethal dose) and the damages of radiation in the amphibia were studied by 3H-TdR from the standpoint of cellular kinetics. The cell mitosis cycle of the amphibia required a long time. The functional cell regeneration and the physiological function of the cell were slower than in mice. The reason for the low radiosensitivity of the amphibia was discussed relative to the environmental factor of temperature. Because the amphibia change body temperature according to environmental temperature, the danger of radiation damage, the actual lethal dose and the period of survival were influenced by the environmental temperature. Acute radiation danger to amphibia was essentially the same as the danger to mammalia, both young and old. LD50 irradiation effects varied among the species. The cell regeneration, turn over, and the mitosis in the amphibia, were affected by environmental temperature, however, the courses proceeded slower than those of the mammalia. Therefore, the question remains, whether the comparison of the radiosensitivities of amphibia with other classes of animal by LDsub(50/30) irradiation was appropriate. (Serizawa, K.)

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

    International Nuclear Information System (INIS)

    Over-expression of epidermal growth factor receptor (EGFR) or insulin-like growth factor-1 receptor (IGF-1R) have been shown to closely correlate with radioresistance of breast cancer cells. This study aimed to investigate the impact of co-inhibition of EGFR and IGF-1R on the radiosensitivity of two breast cancer cells with different profiles of EGFR and IGF-1R expression. The MCF-7 (EGFR +/−, IGF-1R +++) and MDA-MB-468 (EGFR +++, IGF-1R +++) breast cancer cell lines were used. Radiosensitizing effects were determined by colony formation assay. Apoptosis and cell cycle distribution were measured by flow cytometry. Phospho-Akt and phospho-Erk1/2 were quantified by western blot. In vivo studies were conducted using MDA-MB-468 cells xenografted in nu/nu mice. In MDA-MB-468 cells, the inhibition of IGF-1R upregulated the p-EGFR expression. Either EGFR (AG1478) or IGF-1R inhibitor (AG1024) radiosensitized MDA-MB-468 cells. In MCF-7 cells, radiosensitivity was enhanced by AG1024, but not by AG1478. Synergistical radiosensitizing effect was observed by co-inhibition of EGFR and IGF-1R only in MDA-MB-468 cells with a DMF10% of 1.90. The co-inhibition plus irradiation significantly induced more apoptosis and arrested the cells at G0/G1 phase in MDA-MB-468 cells. Only co-inhibition of EGFR and IGF-1R synergistically diminished the expression of p-Akt and p-Erk1/2 in MDA-MB-468 cells. In vivo studies further verified the radiosensitizing effects by co-inhibition of both pathways in a MDA-MB-468 xenograft model. Our data suggested that co-inhibition of EGFR and IGF-1R synergistically radiosensitized breast cancer cells with both EGFR and IGF-1R high expression. The approach may have an important therapeutic implication in the treatment of breast cancer patients with high expression of EGFR and IGF-1R

  11. Hyper-radiosensitivity and induced radioresistance and bystander effects in rodent and human cells as a function of radiation quality

    International Nuclear Information System (INIS)

    In the past two decades, a body of experimental evidences in vitro has shown the presence of a plethora of phenomena occurring after low-dose irradiation [including hypersensitivity and induced radioresistance (IRR), adaptive response, bystander effect (BE) and genomic instability], which might imply a non-linear behaviour of cancer risk curves in the low-dose region and question the validity of the linear no-threshold model for cancer risk assessment in such a dose region. In this framework, a systematic investigation have been undertaken on non-linear effects at low doses as a function of different radiation quality and cellular radiosensitivity and in terms of different biological end points. The present article reports the recent results on hyper-radiosensitivity and IRR and BE phenomena, in terms of clonogenic survival in V79 Chinese hamster cells and T98G human glioblastoma cells irradiated with protons and carbon ions with different energy, as a function of dose (and fluence). (authors)

  12. Radiosensitization of E. coli B/r by the cytotoxic agent procarbazine: a hypoxic cell sensitizer preferentially toxic to aerobic cells and easily oxidized

    International Nuclear Information System (INIS)

    Procarbazine has been shown to be a hypoxic cell sensitizer of moderate ability in E. coli B/r, with an achievable enhancement ratio of 1.4 at subtoxic concentrations. The drug appears to act in a manner similar to that expected with the electron-affinic radiosensitizers. However, procarbazine and the electron-affinic sensitizers differ in two important respects. Unlike the electron-affinic sensitizers, procarbazine is not easily reduced, but is easily oxidized. It is more toxic to aerobic than to hypoxic cells. At the drug dosages in present clinical use, procarbazine is likely to be only a weak radiosensitizer. The possible implications of the data for the further development of a new class of sensitizers and combination therapy are discussed. (author)

  13. RGD-conjugated gold nanorods induce radiosensitization in melanoma cancer cells by downregulating αvβ3 expression

    Directory of Open Access Journals (Sweden)

    Pang B

    2012-02-01

    Full Text Available Wencai Xu1, Teng Luo2, Ping Li1, Chuanqing Zhou2, Daxiang Cui3, Bo Pang4, Qiushi Ren4, Shen Fu11Department of Radiation Oncology, Shanghai Sixth People's Hospital, 2School of Biomedical Engineering, and 3National Key Laboratory of Nano/Micro Fabrication Technology, Key Laboratory for Thin Film and Microfabrication of Ministry of Education, Institute of Micro-Nano Science and Technology, Shanghai Jiao Tong University, Shanghai, 4Department of Biomedical Engineering, College of Engineering, Peking University, Beijing, People's Republic of ChinaBackground: Melanoma is known to be radioresistant and traditional treatments have been intractable. Therefore, novel approaches are required to improve the therapeutic efficacy of melanoma treatment. In our study, gold nanorods conjugated with Arg-Gly-Asp peptides (RGD-GNRs were used as a sensitizer to enhance the response of melanoma cells to 6 mV radiation.Methods and materials: A375 melanoma cells were treated by gold nanorods or RGD-GNRs with or without irradiation. The antiproliferative impact of the treatments was measured by MTT assay. Radiosensitizing effects were determined by colony formation assay. Apoptosis and cell cycle data were measured by flow cytometry. Integrin αvβ3expression was also investigated by flow cytometry.Results: Addition of RGD-GNRs enhanced the radiosensitivity of A375 cells with a dose-modifying factor of 1.35, and enhanced radiation-induced apoptosis. DNA flow cytometric analysis indicated that RGD-GNRs plus irradiation induced significant G2/M phase arrest in A375 cells. Both spontaneous and radiation-induced expressions of integrin αvβ3 were downregulated by RGD-GNRs.Conclusion: Our study indicated that RGD-GNRs could sensitize melanoma A375 cells to irradiation. It was hypothesized that this was mainly through downregulation of radiation-induced αvβ3, in addition to induction of a higher proportion of cells within the G2/M phase. The combination of RGD-GNRs and

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

    Directory of Open Access Journals (Sweden)

    Chih-Chia Yu

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

  15. Regional difference of radiosensitivity of neural cells in the fetal brain of mice on day 13 of gestation

    International Nuclear Information System (INIS)

    Pregnant Slc: ICR mice were exposed to a single whole-body X-irradiation at a dose of 12.5 R or 25 R on day 13 of gestation. After irradiation, fetuses were obtained from mothers at 1- or 3-hour intervals and coronal histological sections were made. Pyknotic cells were counted in the ventricular zone of brain mantle, hippocampal anlage and olfactory bulb. In the 25 R group, peak incidences of pyknotic cells in brain mantle, hippocampal anlage and olfactory bulb were 13.2 %, 6.9 % and 2.2 %, respectively. In the 12.5 R group, these were 6.0 %, 3.2 % and 1.7 %, respectively. This result indicates that neural cells in the ventricular zone of brain mantle are the most radiosensitive among the cerebral regions examined in day-13 mouse fetuses. (author)

  16. Evaluation of energy deposition to the urinary bladder wall considering radiosensitive basal cells by beta-ray emitters

    International Nuclear Information System (INIS)

    The present report describes the dose evaluation of the urinary bladder since its absorbed dose from radiopharmaceuticals tends to be higher than other organs. For an accurate dose evaluation, a simple bladder model considering radiosensitive basal cells was used to calculate SAF (specific absorbed fractions) for the basal cells and the whole bladder wall from mono energetic photon and electron sources using Monte Carlo simulation. Furthermore, S values (the mean absorbed doses for the target organ per unit cumulated activity in the source organ) were evaluated for 36 beta-ray emitters. Consequently, considering basal cells and beta particle spectra in the evaluation of absorbed dose for the urinary bladder are very important for an accurate evaluation. (author)

  17. Effect of alpha-tocopherol and alpha-tocopheryl quinone on the radiosensitivity of thiol-depleted mammalian cells

    International Nuclear Information System (INIS)

    The effect of hypoxic cell radiosensitizers is increased when mammalian cells are depleted of endogenous glutathione by buthionine sulphoximine pre-treatment in vitro; a similar gain has not been observed in tumors in vivo despite evidence of glutathione depletion in vivo following buthionine sulphoximine treatment. However, concentrations of biological reducing agents other than glutathione were not measured in the in vivo experiments. Other reducing agents found in tumors include alpha-tocopherol, which reduces the sensitizing efficiency of nitro-aromatic sensitizers in thiol-depleted mammalian cells. These data suggest that the failure to observe large gains in misonidazole sensitizing efficiency in thiol-depleted tumors in vivo may be due, in part, to the presence of biological reducing agents such as alpha-tocopherol

  18. Effect of alpha-tocopherol and alpha-tocopheryl quinone on the radiosensitivity of thiol-depleted mammalian cells

    Energy Technology Data Exchange (ETDEWEB)

    Hodgkiss, R.J.; Stratford, M.R.; Watfa, R.R.

    1989-05-01

    The effect of hypoxic cell radiosensitizers is increased when mammalian cells are depleted of endogenous glutathione by buthionine sulphoximine pre-treatment in vitro; a similar gain has not been observed in tumors in vivo despite evidence of glutathione depletion in vivo following buthionine sulphoximine treatment. However, concentrations of biological reducing agents other than glutathione were not measured in the in vivo experiments. Other reducing agents found in tumors include alpha-tocopherol, which reduces the sensitizing efficiency of nitro-aromatic sensitizers in thiol-depleted mammalian cells. These data suggest that the failure to observe large gains in misonidazole sensitizing efficiency in thiol-depleted tumors in vivo may be due, in part, to the presence of biological reducing agents such as alpha-tocopherol.

  19. Effect and Mechanism of Radiosensitization of Poly (ADP-Ribose Polymerase 
Inhibitor on Lewis Cells and Xenografts

    Directory of Open Access Journals (Sweden)

    Wei WANG

    2016-01-01

    Full Text Available Background and objective The DNA damage of the irradiated tumor cells is mainly single strand breaks (SSBs and double strand breaks (DSBs, in which the frequency of occurrence of SSBs is dozens of times than DSBs. However, most of the SSBs could be repaired by the Poly (ADP-Ribose Polymerase (PARP and other related factors. Recently listed drug-Olaparib (PARP1/PARP2/PARP3 inhibitor could target the repair pathways of single strand breaks, and recent clinical trials of PARP inhibitors combined with chemotherapy obtained encouraging results. The aim of this study is to investigate the effect and potential mechanism of radiosensitization of Poly (ADP-Ribose polymerase inhibitor-Olaparib on lewis cells and xenografts. Methods The inhibition concentration 10% inhibitory concentration (IC10 of Olaparib to Lewis cells was detected by methyl thiazolyltetrazolium (MTT assay. The radiosensitization effect of Olaparib on Lewis cells was determined by classical colony forming assay. Lewis xenografts models were established, and the mice were randomly divided into four groups: Control group, Olaparib group, Radiotherapy group (RT, 2 Gy×5 d, Olaparib combined with RT group. Xenograft volume was measured during the treatment. Flow cytometry was used to analyze the apoptosis rate of the Lewis cells in each group, and the apoptosis of xenograft tissues was observed by TUNEL stain. The ralative protein levels of γH2AX (associated with DNA strand breaks repair, Bax/Bcl-2, Caspase-3 (apoptosis-associated protein were detected by Western blot in vitro and in vivo. Results The IC10 value of Olaparib was 4.4 µmol/L. The radio-sensitivity enhancement ratio (SER of Olaparib combined with RT was 1.211 in vitro. Compared with RT (2 Gy×5 d alone, the combination of Olaparib with fractionated radiotherapy significantly increased the growth delay of Lewis xenografts (P<0.001. Flow cytometry and TUNEL analysis indicated that the apoptosis rate in the combination group was

  20. Involvement of placental/umbilical cord blood acid–base status and gas values on the radiosensitivity of human fetal/neonatal hematopoietic stem/progenitor cells

    OpenAIRE

    Yamaguchi, Masaru; EBINA, SATOKO; Kashiwakura, Ikuo

    2012-01-01

    Arterial cord blood (CB) acid–base status and gas values, such as pH, PCO2, PO2, HCO3 −and base excess, provide useful information on the fetal and neonatal condition. However, it remains unknown whether these values affect the radiosensitivity of fetal/neonatal hematopoiesis. The present study evaluated the relationship between arterial CB acid–base status, gas values, and the radiosensitivity of CB hematopoietic stem/progenitor cells (HSPCs). A total of 25 CB units were collected. The arter...

  1. Control of polyclonal immunoglobulin production from human lymphocytes by leukotrienes; leukotriene B4 induces an OKT8(+), radiosensitive suppressor cell from resting, human OKT8(-) T cells

    International Nuclear Information System (INIS)

    We report that leukotriene B4 (LTB4), a 5-lipoxygenase metabolite of arachidonic acid, is a potent suppressor of polyclonal Ig production in pokeweed mitogen (PWM)-stimulated cultures of human peripheral blood lymphocytes, while LTC4 and LTD4 have little activity in this system. Preincubation of T cells with LTB4 in nanomolar to picomolar concentrations rendered these cells suppressive of Ig production in subsequent PWM-stimulated cultures of fresh, autologous B + T cells. This LTB4-induced suppressor cell was radiosensitive, and its generation could be blocked by cyclohexamide but not by mitomycin C. The LTB4-induced suppressor cell was OKT8(+), while the precursor for the cell could be OKT8(-). The incubation of OKT8(-) T cells with LTB4 for 18 h resulted in the appearance of the OKT8(+) on 10-20% of the cells, and this could be blocked by cyclohexamide but not by mitomycin C. Thus, LTB4 in very low concentrations induces a radiosensitive OKT8(+) suppressor cell from OKT8(-) cells. In this regard, LTB4 is three to six orders of magnitude more potent than any endogenous hormonal inducer of suppressor cells previously described. Glucocorticosteroids, which block suppressor cell induction in many systems, may act by inhibiting endogenous production of LTB4

  2. Radiosensitizing Effects of Ectopic miR-101 on Non–Small-Cell Lung Cancer Cells Depend on the Endogenous miR-101 Level

    International Nuclear Information System (INIS)

    Purpose: Previously, we showed that ectopic miR-101 could sensitize human tumor cells to radiation by targeting ATM and DNA-PK catalytic subunit (DNA-PKcs) to inhibit DNA repair, as the endogenous miR-101 levels are low in tumors in general. However, the heterogeneity of human cancers may result in an exception. The purpose of this study was to test the hypothesis that a few tumor cell lines with a high level of endogenous miR-101 would prove less response to ectopic miR-101. Methods and Materials: Fourteeen non–small-cell lung cancer (NSCLC) cell lines and one immortalized non-malignant lung epithelial cell line (NL20) were used for comparing endogenous miR-101 levels by real-time reverse transcription–polymerase chain reaction. Based on the different miR-101 levels, four cell lines with different miR-101 levels were chosen for transfection with a green fluorescent protein–lentiviral plasmid encoding miR-101. The target protein levels were measured by using Western blotting. The radiosensitizing effects of ectopic miR-101 on these NSCLC cell lines were determined by a clonogenic assay and xenograft mouse model. Results: The endogenous miR-101 level was similar or lower in 13 NSCLC cell lines but was 11-fold higher in one cell line (H157) than in NL20 cells. Although ectopic miR-101 efficiently decreased the ATM and DNA-PKcs levels and increased the radiosensitization level in H1299, H1975, and A549 cells, it did not change the levels of the miR-101 targets or radiosensitivity in H157 cells. Similar results were observed in xenograft mice. Conclusions: A small number of NSCLC cell lines could have a high level of endogenous miR-101. The ectopic miR-101 was able to radiosensitize most NSCLC cells, except for the NSCLC cell lines that had a much higher endogenous miR-101 level. These results suggest that when we choose one miRNA as a therapeutic tool, the endogenous level of the miRNA in each tumor should be considered.

  3. Radiosensitizing Effects of Ectopic miR-101 on Non-Small-Cell Lung Cancer Cells Depend on the Endogenous miR-101 Level

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Susie; Wang Hongyan; Ng, Wooi Loon; Curran, Walter J. [Department of Radiation Oncology, School of Medicine and the Winship Cancer Institute, Emory University, Atlanta, GA (United States); Wang Ya, E-mail: ywang94@emory.edu [Department of Radiation Oncology, School of Medicine and the Winship Cancer Institute, Emory University, Atlanta, GA (United States)

    2011-12-01

    Purpose: Previously, we showed that ectopic miR-101 could sensitize human tumor cells to radiation by targeting ATM and DNA-PK catalytic subunit (DNA-PKcs) to inhibit DNA repair, as the endogenous miR-101 levels are low in tumors in general. However, the heterogeneity of human cancers may result in an exception. The purpose of this study was to test the hypothesis that a few tumor cell lines with a high level of endogenous miR-101 would prove less response to ectopic miR-101. Methods and Materials: Fourteeen non-small-cell lung cancer (NSCLC) cell lines and one immortalized non-malignant lung epithelial cell line (NL20) were used for comparing endogenous miR-101 levels by real-time reverse transcription-polymerase chain reaction. Based on the different miR-101 levels, four cell lines with different miR-101 levels were chosen for transfection with a green fluorescent protein-lentiviral plasmid encoding miR-101. The target protein levels were measured by using Western blotting. The radiosensitizing effects of ectopic miR-101 on these NSCLC cell lines were determined by a clonogenic assay and xenograft mouse model. Results: The endogenous miR-101 level was similar or lower in 13 NSCLC cell lines but was 11-fold higher in one cell line (H157) than in NL20 cells. Although ectopic miR-101 efficiently decreased the ATM and DNA-PKcs levels and increased the radiosensitization level in H1299, H1975, and A549 cells, it did not change the levels of the miR-101 targets or radiosensitivity in H157 cells. Similar results were observed in xenograft mice. Conclusions: A small number of NSCLC cell lines could have a high level of endogenous miR-101. The ectopic miR-101 was able to radiosensitize most NSCLC cells, except for the NSCLC cell lines that had a much higher endogenous miR-101 level. These results suggest that when we choose one miRNA as a therapeutic tool, the endogenous level of the miRNA in each tumor should be considered.

  4. Adenovirus-mediated gene transduction of truncated lκBα enhances radiosensitivity in human colon cancer cells

    International Nuclear Information System (INIS)

    Nuclear factor kappa B (NF-κB) is a transcription factor that is known to regulate apoptosis when cells are exposed to DNA-damaging agents such as ionizing radiation and cytotoxic drugs. We sought to determine if inhibition of NF-κB could enhance radiosensitivity in human colon cancer cells in vitro and in vivo. To inhibit NF-κB activation specifically, we constructed a recombinant adenovirus vector expressing a truncated form of the inhibitor protein IκBα (IκBαΔN) that lacks the phosphorylation sites essential for activation of NF-κB, and transfected two human colon cancer cell lines (HT29 and HCT15) with this vector. In vitro colony-forming assays revealed that the overexpression of the stable lκBα by AxIκBαΔN infection significantly suppressed cell growth after irradiation in both cell lines as compared to infection with a control vector, AxLacZ. Treatment with AxIκBαΔN and irradiation successfully inhibited the growth of HT29 xenografted subcutaneous tumors in nude mice with an 83.8% volume reduction on day 38 as compared to the untreated tumors. Furthermore, it was demonstrated that apoptosis was increased by adenovirus-mediated gene transduction of IκBαΔN in vitro and in vivo. These results indicated that inhibition of NF-κB could enhance radiosensitivity through an increase in radiation-induced apoptosis. We believe that radio-gene therapy using adenovirus-mediated gene transduction of IκBαΔN could be an attractive candidate as a treatment strategy for colorectal cancer. (author)

  5. Pre-treatment number of clonogenic cells and their radiosensitivity are major determinants of local tumour control after fractionated irradiation

    International Nuclear Information System (INIS)

    Objective: The response of tumours to fractionated radiotherapy is determined by many factors including repopulation, reoxygenation, the number of clonogenic cells, and their intrinsic radiosensitivity. However, after single radiation doses given under conditions of clamp hypoxia, the dose to control a tumour locally is dependent only on the number of clonogenic cells and their cellular radiosensitivity. Therefore, these parameters were investigated using local control after single doses given under hypoxia, to predict the outcome of fractionated irradiation. Materials and methods: Ten hSCC cell lines (FaDu, UT-SCC-15, UT-SCC-14, XF354, UT-SCC-5, UT-SCC-45, SAS, CAL-33, UT-SCC-8, and HSC-4) were transplanted subcutaneously into the right hind-leg of NMRI nude mice. At 7 mm in diameter, tumours were irradiated either with graded single doses under clamp blood flow conditions (n = 873) or with 30 graded fractions within 6 weeks (n = 905) under ambient conditions. Local tumour control was determined 120 days after irradiation. Radiation response was quantified in terms of TCD50, i.e. the dose required to control 50% of tumours locally. Results: Ten tumour lines investigated showed a pronounced heterogeneity in both TCD50(30fx/6w) after fractionated irradiation and TCD50(SDclamp) after single dose irradiation. TCD50(30fx/6w) varied between 45 Gy for UT-SCC-45 and 127 Gy for SAS; TCD50(SDclamp) varied between 42 Gy for UT-SCC-14 and 66 Gy for CAL-33. Two tumours were excluded from further analysis due to immunogenicity or non-defined TCD50. Linear regression analysis revealed a significant positive correlation between TCD50(SDclamp) and TCD50(30fx/6w) (R 2 = 0.82, p = 0.002). Conclusions: Significant association between TCD50(SDclamp) and TCD50(30fx/6w) suggests that the pre-treatment number of clonogenic tumour cells and their cellular radiosensitivity have a major impact on local control after fractionated radiotherapy

  6. ATM dependent low-dose hyper-radiosensitivity in mutation induced by heavy ions in mammalian cells

    International Nuclear Information System (INIS)

    On the basis of our last year's work that proved the existence of Low dose Hyper-radiosensitivity (HRS) and later appeared radioresistance (termed Induced radioresistance (IRR)) in normal human skin fibroblast cells exposed to carbon ions irradiation with the endpoints of survival and mutation, we further study the role of ataxia telangiectasia mutated (ATM) kinase, which has been indicated to work in the mechanism of HRS/IRR by low linear energy transfer (LET) irradiation. Normal human fibroblast cells were pretreated with stimulator for ATM kinase, chloroquine, or with ATM inhibitor, KU55933 prior to carbon irradiation, survival fraction and HPRT mutation frequency were measured to test the existence of HRS/IRR. Interestingly there was no HRS/IRR in either ATM stimulator or inhibitor pretreatment. The western blot suggest a dose-dependent increase of ATM kinase activity, which further confirm the role of ATM in the mechanism of HRS/IRR. (author)

  7. Effect of c- erbB2 Antisense Oligodeoxynucleotides on Radiosensitivity of Human Ovarian Cancer Cell Line

    Institute of Scientific and Technical Information of China (English)

    RENQing-Lan

    2003-01-01

    Object To explore tile effect of lipofectin - c - erbB2 antisense oligodeoxynucleotides on radiosensitivity of human ovarian cancer cell llne. Methods The expression of c - erbB2 was detected by means of RT - PCR, cellular response to irradiation was evaluated by tile colony forming assay. Results Lipofectin- c - erbB2 antisense oligodeoxynucleotides(AS- ODN) could suppress the expression of c - erbB2 , and significantly decreased the colony forming rate of human ovarian cancer cells after ionizing irradiation (P 0.05 ). Condusion c - erbB2 antisense oligodeoxynueleotides sensitized the SKOV3 to ionizing irradiation through decreasing the expression of e - erbB2 , which might be the result of the fact that c - erbB2 antisense oligodeoxynueleotides inhibit the eelluar signal transductionpathway relating to the radiation- resistant phenotype.

  8. Heat damage to DNA polymerases as a possible cause for hyperthermic cell killing and radiosensitization by heat

    International Nuclear Information System (INIS)

    Reports in the literature suggest a causal relationship between heat effects on the activity of DNA polymerase β and hyperthermic cell killing. By using thermotolerance as a tool to investigate this possibility it was found that a poor correlation existed between these two parameters, but a good correlation was observed between the decrease in activity of this enzyme and the extent of radiosensitization by heat. To further pursue the role of DNA polymerases in the mechanism of cell killing, step-down heating procedures were introduced. No sensitization of polymerase inactivation was observed with this treatment. From the results of the experiments reported, the authors like to conclude that heat inactivation of DNA polymerase β is not to be considered as the general cause of hypethermic death

  9. Radiosensitization conferred by oxygen and hypoxic cell sensitizers on human cells cultivated in vitro

    International Nuclear Information System (INIS)

    The main purpose was to provide additional information on two questions; (1) How does the radiosensitising effect of oxygen depend on oxygen concentration and cellular age, and (2) How does the radiosensitising effect of hypoxic cell sensitisers depend on concentration of sensitiser and cellular age. The general conclusions reached were as follows. The radiosensitising effect of oxygen on NHIK 3025 cells in G1 increased with increasing dose of radiation. For cells irradiated in S oxygen acted as a dose-modifying agent. For small doses of radiation the sensitising effect of oxygen was weaker for cells irradiated in G1 than for cells irradiated in S. The capacity of NHIK 3025 cells to repair sublethal damage after irradiation under extremely hypoxic conditions was low or even lost (even though the cells were subsequently incubated under aerobic conditions). The radiosensitising effect conferred by TMPN, diamide and misonidazole on NHIK 3025 cells was higher at high doses of radiation than at small doses of radiation (except for the dose-modifying radiosensitisation of cells in S by misonidazole). This observation supports arguments for using high dose fractions in fractionated radiotherapy where such chemicals are involved. (JIW)

  10. Polyfunctional radiosensitizers: VI. Dexamethasone inhibits shoulder modification by uncharged nitroxyl biradicals in mammalian cells irradiated in vitro

    International Nuclear Information System (INIS)

    Overnight exposure of Chinese hamster cells (V.79-753B) in vitro to 1 μg/ml dexamethasone increases the radiation resistance of the cells by about 20% both in air and in hypoxia, while having no appreciable effect on the oxygen enhancement ratio (OER). This is accompanied by substantially higher levels of glutathione. When dexamethasone-treated hypoxic cells are irradiated in the presence of nitroxyl biradicals there is no effect on the slope ratio of the exponential portion of the survival curves. In the case of uncharged biradicals, Ro.03-6061 and RSU-4072, which have been shown to modify the shoulder region of the hypoxic cell survival curve, there is an increase in extrapolation number in dexamethasone-treated cells. When hypoxic cells are exposed to the charged biradical RSU-4073, which does not exhibit shoulder modification, there is no change in extrapolation number. Experiments to examine the effect of concentration of these compounds on radiosensitization show that lower concentrations of both RSU-4072 and RSU-4073 are required to mediate changes in the slope of the hypoxic cell survival curve than to mediate shoulder modification, in the case of RSU-4072. Quantitative ESR data comparing the uptake of RSU-4072 and RSU-4073 with the monoradical TMPN into cells suggest that the cell membrane may act as a barrier to the incorporation of biradicals, and that this is greater for charged than for uncharged compounds. Treatment of cells with dexamethasone does not affect the uptake of the compounds

  11. Further characterization of the adhesive-tumor-cell culture system for measuring the radiosensitivity of human tumor primary cultures

    International Nuclear Information System (INIS)

    This study extends the use of the adhesive-tumor-cell culture system to include: over 100 sensitivity measurements at 2.0 Gy; tumorgenicity determinations in nude mice; and flow cytometry of the cells grown in the system. The malignant nature of the growing cells was proved by injecting cells into nude mice. Tumors resulted in 60% of the cases and the histology of each xenograft was similar to that of the human tumor. Flow cytometry was used to obtain DNA histograms of the original cell suspension and of cultures during the two week culture period in order to obtain quantitative information about the growth of aneuploid versus diploid populations. The results thus far demonstrate that 95% of aneuploid populations yield aneuploid growth; of the first 20 cases studied, only one suspension with an aneuploid peak resulted in diploid growth. Of further interest was the observation that it is not unusual for a minor aneuploid population to become the predominate growth fraction after two weeks in culture. These results demonstrate that the adhesive-tumor-cell culture system supports the growth of malignant cells, that multiple cell populations exist in cell suspensions derived from solid tumors, and that differences exist between the radiosensitivity of cells at 2.0 Gy in different histology types

  12. Low dose hyper-radiosensitivity in human lung cancer cell line A549 and its possible mechanisms

    International Nuclear Information System (INIS)

    Objective: To study the low dose hyper-radiosensitivity in human lung cancer cell line A549, and its possible mechanisms. Methods: Exponentially growing A549 cells were irradiated with 60Co γ-rays at doses of 0-2 Gy. Together with flow cytometry for precise cell sorting, cell survival fraction was measured by mean of conventional colony-formation assay. ATM1981 Ser-P protein expression was examined by Western blot. Apoptosis was identified by Hoechst 33258 fluorescent staining, and Annexin V-FITC and propidium iodide staining flow cytometry. Cell cycle distribution was observed by flow cytometry. Results: There was an excessive cell killing per unit dose when the doses were below about 0.3 Gy, and the cells exhibited more resistant response at the doses between 0.3 and 0.5 Gy, the cell survival fraction was decreased as the doses over 0.5 Gy. The expression of ATM1981Ser-P protein was first observed at 0.2 Gy, followed by an increase over 0.2 Gy, and reached the peak at 0.5 Gy (compared with 0.2 Gy group, t=7.96, P0.05). 24 hours after irradiation, part cells presented the characteristic morphological change of apoptosis, and the apoptosis curve was coincident with the dose-survival curve. Compared with the control group, the cell cycle had no change post-irradiation to 0.1 and 0.2 Gy. G2/M phase arrest was manifested at 6 and 12 hours post-irradiation to 0.3, 0.4 and 0.5 Gy (t=2.87, 2.88, 4.92 and 3.70, 3.12, 8.11, P2/M phase was decreased at 24 hours post-irradiation (t=3.87, 4.77, 3.01, P<0.05). Conclusions: A549 cells displays the phenomenon of hyper-radiosensitivity (HRS) /induced radioresistance (IRR). The model of cell death induced by low dose irradiation is mainly apoptosis. The activity of ATM and cell cycle change might play an important role in HRS/IRR. (authors)

  13. Reciprocal translocation frequency in irradiated sensitive and resistant human tumor cells in correlation with clonogenic in vitro cell survival: a possibility of tumor radiosensitivity prediction?

    International Nuclear Information System (INIS)

    We have investigated the yields of radiation-induced translocation in several human tumor cell lines and in normal diploid human fibroblasts by fluorescence in situ hybridization. The translocation yields were determined with respect to chromosome no. 1 in all cell lines investigated, and moreover in chromosomes nos. 2, 4 and 9 in fibroblasts and one tumor cell line. The chromosomes were 'painted' with fluorescent whole chromosome-hybridization probes. The clonogenic survival of the studied cell lines was determined by standard colony-formation assay. We observed a higher frequency of reciprocal translocations in the radiosensitive cells MCF-7 and MDA-MB-436 as compared with the radioresistant cells CaSki and normal skin fibroblasts. Thus, the results suggest a possibility to predict the intrinsic tumor radiosensitivity on the basis of reciprocal translocation yield determined in cells irradiated in vitro. The correlation was observed in spite of the trisomy no. 1 which occurred in all three investigated tumor cell lines. On the other hand, the results obtained with different chromosomes in MCF-7 cells suggest that only chromosomes with relatively low 'spontaneous' translocation yields are suitable for this kind of analysis

  14. Radiosensitivity of AsPC-1 cell to γ-rays enhanced by up-regulation of PUMA induced by targeted Slug gene

    International Nuclear Information System (INIS)

    Objective: To explore the influence of PUMA on radiosensitivity of pancreatic cancer AsPC-1 cells after Slug gene inhibition by transfected short interferencing RNA (siRNA). Methods: The AsPC-1 cells were infected with MOI 10, 50, 100 for 72 h, respectively. The expression of Slug and PUMA was analyzed by Western blotting and immunohistochemistry methods. The transfected and control cells were exposed to 4 Gy γ-rays. The cells inhibition rate was examined by MTT, Hoechst 33342 and IP double staining. DNA ladder and Giemsa staning was used to observe apoptosis. Results: The relative value of Slug expression was 0.831±0.14, 0.546±0.12 and 0.178±0.08 after AsPC-1 was infected with Slug-siRNA (MOI 10, 50, 100) for 72 h, significantly lower than that of control group (F=4.992, P<0.05). The relative value of PUMA was 0.325±0.07, 0.593±0.11 and 0.978±0.12, after AsPC-1 was infected with Slug-siRNA (MOI 10, 50, 100) for 72 h, significantly higher than that of control group (F=4.324, P<0.05). The cell proliferation rate was (78.76±9.36)% in transfection combined with radiosensitivity group, significantly higher than that of transfection group [(43.68±6.71)%] and radiosensitivity group alone [(19.25±3.72)%] (F=5.056, P<0.05). The apoptosis of transfection combined with radiosensitivity group was significantly higher than that of others. Conclusions: Slug gene targeting siRNA could inhibit the expression of Slug, and consequently increase the activation of PUMA expression, and so enhance the radiosensitivity to γ-rays. (authors)

  15. Radiosensitization of human glioma cells in vitro and in vivo with acyclovir and mutant HSV-TK75 expressed from adenovirus

    International Nuclear Information System (INIS)

    Purpose: We recently reported that an adenovirus-expressing mutant HSV-TK75 (AdCMV-TK75) radiosensitized rat syngeneic gliomas in combination with low concentrations of acyclovir (ACV) much more effectively than a virus expressing wild-type herpes simplex virus thymidine kinase (HSV-TK). In this report we have examined whether similar radiosensitizing effects are also seen with human glioma cells in vitro and in vivo. Methods and Materials: Human U87 MG glioma cells were transduced with AdCMV-TK75 and exposed to ACV followed by single-dose irradiation and colony-forming survival assays. Similarly, U87 MG xenografts were infused with AdCMV-TK75 or Adβgal control virus, followed by ACV administration and fractionated irradiation. Therapeutic efficacy was monitored by tumor growth. Results: U87 MG cells transduced with AdCMV-TK75 were significantly more sensitive to ACV (3 μM) than cells transduced with either wild-type HSV-TK or control virus. To determine whether human cells also demonstrate improved radiosensitization similar to that seen with rat glioma cells and tumors, we transduced U87 MG cells with either AdCMV-TK75, AdCMV-TK, expressing wild-type HSV-TK, or Adβgal and then treated the cells with 3 μM of ACV. Cells transduced with AdCMV-TK75 were significantly more radiosensitive (dose enhancement ratio [D37]: 2.6) by colony-forming survival assay than cells transduced with either AdCMV-TK or Adβgal. Furthermore, we found that U87 MG xenografts infused with AdCMV-TK75 by slow positive pressure infusion were more radiosensitive after administration of ACV than tumors infused with Adβgal. A more dramatic result was achieved when fractionated irradiation was carried out concurrently with ACV administration, in which case AdCMV-TK75-treated tumors did not grow at all. Conclusions: These results demonstrate that transduction of human glioma cells in vitro and infusion of xenografts in vivo with AdCMV-TK75 and treatment with concentrations of ACV that can be

  16. Correlativity study between expression of DNA double-strand break repair protein and radiosensitivity of tumor cells

    Institute of Scientific and Technical Information of China (English)

    Liang ZHUANG; Shiying YU; Xiaoyuan HUANG; Yang CAO; Huihua XIONG

    2009-01-01

    DNA double-strand break (DSB) is generally regarded as the most lethal of all DNA lesions after radiation. KuS0, DNA-PK catalytic subunit (DNA-PKcs) and ataxia telangiectasia mutated (ATM) proteins are major DSB repair proteins. In this study, survival fraction at 2Gy (SF2) values of eight human tumor cell lines (including four human cervical carcinoma cell lines HeLa, SiHa, C33A, Caski, three human breast carcinoma cell lines MCF-7, MDA-MB-231, MDA-MB-453, and one human lung carcinoma cell line A549) were acquired by clone formation assay, and western blot was applied to detect the expressions of Ku80, DNA-PKcs and ATM protein. The correlativity of protein expression with SF2 value was analyzed by Pearson linear correlation analysis. We found that the expression of the same protein in different cell lines and the expression of three proteins in the same cell line had a significant difference. The SF2 values were also different in eight tumor cell lines and there was a positive correlativity between the expression of DNA-PKcs and SF2 (r=0.723, P =0.043), but Ku80 and ATM expression had no correlation with SF2 (P>0.05). These findings suggest that the expression level of DNA-PKcs protein can be an indicator for predicting the radiosensitivity of tumor cells.

  17. Comparison of radiosensitivity and thermosensitivity among three types of cultured mammalian cells and detection of heat-induced cell killing by eosin-staining method

    Energy Technology Data Exchange (ETDEWEB)

    Kashiwado, Kouzou

    1988-12-01

    Radiosensitivity, Thermosensitivity and their combined sensitivity on cell death were studied using mouse L5178Y, mouse FM3A and human Burkitt lymphoma. Eosin-staining method was tested for counting the heat-induced dead cells. The results obtained in the present study were as follows: (1) In irradiation with /sup 60/Co gamma-rays D/sub 0/ values of 1.3 Gy, 1.4 Gy and 1.7 Gy were obtained for Burkitt lymphoma, L5178Y and FM3A respectively. (2) By heating at 43degC, T/sub 0/ values of 4.1 min, 12.5 min and 32 min were obtained for L5178Y, FM3A and Burkitt lymphoma respectively. (3) Thermotolerance decay depended on cell doubling time, that is, the shorter the doubling time, the faster the decay. Furthermore, the cell line with the higher thermosensitivity showed a faster decay of thermotolerance for the three cell lines used in the present study. (4) The radiosensitizing effects were nearly the same in all three cell lines. (5) Using eosin-staining method, the cell survival curves after hyperthermia were ascertained and compared with those obtained by colony forming method. In L5178Y the survival curves obtained by the two methods were nearly the same. In FM3A only some correlation was found betweewn the cell survival curves obtained by the two methods but in Burkitt lymphoma no correlation was found. (author) 52 refs.

  18. The cytotoxicity of nitroaromatic hypoxic cell radiosensitizers on mammalian cells in vitro

    International Nuclear Information System (INIS)

    The cytotoxic action of several representative nitroaromatic compounds towards Chinese hamster V79 cells in vitro was investigated. Particular reference is made to the 2-nitroimidazole, misonidazole. The results showed that compounds, which are likely to affect the rate and extent of reduction of the nitro group, can alter the cytotoxicity of nitroaromatic compounds under hypoxic conditions. Inhibition of oxygen utilization in aerobic cells by respiratory inhibitors can be relieved by the addition of misonidazole. The presence of these inhibitors or exogenous compounds which can act as energy sources, can change the survival response of mammalian cells to misonidazole both aerobic and hypoxic conditions. Post-incubation of cells in caffeine after exposure to either misonidazole, metronidazole or nitrofurantoin accentuates the degree of cell-killing, probably by inhibition of repair of DNA damage. Several of these nitroaromatic compounds are weakly mutagenic, as demonstrated by resistance to the toxic action of Ouabain and Thioguanine. The mechanistic implications of these results and the relevance to the use of these compounds in cancer therapy are discussed. (author)

  19. Electron spin resonance studies on the detectability of radiation damage and radiosensitization of neoplastic cells. Coordinated programme on improvement of radiotherapy of cancer using modifiers of radiosensitivity of cells

    International Nuclear Information System (INIS)

    The comparison of direct and indirect ESR methods applicable for the examination of radiation damage to melanoma cells leads to the conclusion that only the indirect ones appear to be useful for its detection. The new results of animal experiments and clinical trials carried out according to the rules of radio-chelation therapy are briefly discussed. Selective incorporation of 35S-labelled compounds by pigmented hamster melanoma cells was found to be followed by a depression of their proliferative activity in vitro and in situ, which may suggest the possible therapeutic value of endo-irradiation. The ESR measurements performed with the use of newly elaborated indirect methods revealed that pigmented and non-pigmented cells consume oxygen at significantly different rates, which means that oxygen utilization may contribute to the overall level of radioresistance of melanoma cells. This assumption has been confirmed by comparing the radiosensitivity of melanotic and amelanotic cells to fast neutrons. Pigment-containing hamster melanoma cells which are twice as resistant to low LET radiation as their non-pigmented counterparts, proved to be equally susceptible to neutrons. The chance of improving the efficiency of radiotherapy of malignant melanomas does not appear unlikely in the light of new experimental data and clinical trials

  20. Enhancement of radiosensitivity in human glioblastoma cells by the DNA N-mustard alkylating agent BO-1051 through augmented and sustained DNA damage response

    Science.gov (United States)

    2011-01-01

    Background 1-{4-[Bis(2-chloroethyl)amino]phenyl}-3-[2-methyl-5-(4-methylacridin-9-ylamino)phenyl]urea (BO-1051) is an N-mustard DNA alkylating agent reported to exhibit antitumor activity. Here we further investigate the effects of this compound on radiation responses of human gliomas, which are notorious for the high resistance to radiotherapy. Methods The clonogenic assay was used to determine the IC50 and radiosensitivity of human glioma cell lines (U87MG, U251MG and GBM-3) following BO-1051. DNA histogram and propidium iodide-Annexin V staining were used to determine the cell cycle distribution and the apoptosis, respectively. DNA damage and repair state were determined by γ-H2AX foci, and mitotic catastrophe was measure using nuclear fragmentation. Xenograft tumors were measured with a caliper, and the survival rate was determined using Kaplan-Meier method. Results BO-1051 inhibited growth of human gliomas in a dose- and time-dependent manner. Using the dosage at IC50, BO-1051 significantly enhanced radiosensitivity to different extents [The sensitizer enhancement ratio was between 1.24 and 1.50 at 10% of survival fraction]. The radiosensitive G2/M population was raised by BO-1051, whereas apoptosis and mitotic catastrophe were not affected. γ-H2AX foci was greatly increased and sustained by combined BO-1051 and γ-rays, suggested that DNA damage or repair capacity was impaired during treatment. In vivo studies further demonstrated that BO-1051 enhanced the radiotherapeutic effects on GBM-3-beared xenograft tumors, by which the sensitizer enhancement ratio was 1.97. The survival rate of treated mice was also increased accordingly. Conclusions These results indicate that BO-1051 can effectively enhance glioma cell radiosensitivity in vitro and in vivo. It suggests that BO-1051 is a potent radiosensitizer for treating human glioma cells. PMID:21244709

  1. Enhancement of radiosensitivity in human glioblastoma cells by the DNA N-mustard alkylating agent BO-1051 through augmented and sustained DNA damage response

    Directory of Open Access Journals (Sweden)

    Chen Ming-Teh

    2011-01-01

    Full Text Available Abstract Background 1-{4-[Bis(2-chloroethylamino]phenyl}-3-[2-methyl-5-(4-methylacridin-9-ylaminophenyl]urea (BO-1051 is an N-mustard DNA alkylating agent reported to exhibit antitumor activity. Here we further investigate the effects of this compound on radiation responses of human gliomas, which are notorious for the high resistance to radiotherapy. Methods The clonogenic assay was used to determine the IC50 and radiosensitivity of human glioma cell lines (U87MG, U251MG and GBM-3 following BO-1051. DNA histogram and propidium iodide-Annexin V staining were used to determine the cell cycle distribution and the apoptosis, respectively. DNA damage and repair state were determined by γ-H2AX foci, and mitotic catastrophe was measure using nuclear fragmentation. Xenograft tumors were measured with a caliper, and the survival rate was determined using Kaplan-Meier method. Results BO-1051 inhibited growth of human gliomas in a dose- and time-dependent manner. Using the dosage at IC50, BO-1051 significantly enhanced radiosensitivity to different extents [The sensitizer enhancement ratio was between 1.24 and 1.50 at 10% of survival fraction]. The radiosensitive G2/M population was raised by BO-1051, whereas apoptosis and mitotic catastrophe were not affected. γ-H2AX foci was greatly increased and sustained by combined BO-1051 and γ-rays, suggested that DNA damage or repair capacity was impaired during treatment. In vivo studies further demonstrated that BO-1051 enhanced the radiotherapeutic effects on GBM-3-beared xenograft tumors, by which the sensitizer enhancement ratio was 1.97. The survival rate of treated mice was also increased accordingly. Conclusions These results indicate that BO-1051 can effectively enhance glioma cell radiosensitivity in vitro and in vivo. It suggests that BO-1051 is a potent radiosensitizer for treating human glioma cells.

  2. Enhancement of radiosensitivity in human glioblastoma cells by the DNA N-mustard alkylating agent BO-1051 through augmented and sustained DNA damage response

    International Nuclear Information System (INIS)

    1-{4-[Bis(2-chloroethyl)amino]phenyl}-3-[2-methyl-5- (4-methylacridin-9-ylamino)phenyl]urea (BO-1051) is an N-mustard DNA alkylating agent reported to exhibit antitumor activity. Here we further investigate the effects of this compound on radiation responses of human gliomas, which are notorious for the high resistance to radiotherapy. The clonogenic assay was used to determine the IC50 and radiosensitivity of human glioma cell lines (U87MG, U251MG and GBM-3) following BO-1051. DNA histogram and propidium iodide-Annexin V staining were used to determine the cell cycle distribution and the apoptosis, respectively. DNA damage and repair state were determined by γ-H2AX foci, and mitotic catastrophe was measure using nuclear fragmentation. Xenograft tumors were measured with a caliper, and the survival rate was determined using Kaplan-Meier method. BO-1051 inhibited growth of human gliomas in a dose- and time-dependent manner. Using the dosage at IC50, BO-1051 significantly enhanced radiosensitivity to different extents [The sensitizer enhancement ratio was between 1.24 and 1.50 at 10% of survival fraction]. The radiosensitive G2/M population was raised by BO-1051, whereas apoptosis and mitotic catastrophe were not affected. γ-H2AX foci was greatly increased and sustained by combined BO-1051 and γ-rays, suggested that DNA damage or repair capacity was impaired during treatment. In vivo studies further demonstrated that BO-1051 enhanced the radiotherapeutic effects on GBM-3-beared xenograft tumors, by which the sensitizer enhancement ratio was 1.97. The survival rate of treated mice was also increased accordingly. These results indicate that BO-1051 can effectively enhance glioma cell radiosensitivity in vitro and in vivo. It suggests that BO-1051 is a potent radiosensitizer for treating human glioma cells

  3. Down-regulation of BTG1 by miR-454-3p enhances cellular radiosensitivity in renal carcinoma cells

    International Nuclear Information System (INIS)

    B cell translocation gene 1 (BTG1) has long been recognized as a tumor suppressor gene. Recent reports demonstrated that BTG1 plays an important role in progression of cell cycle and is involved in cellular response to stressors. However, the microRNAs mediated regulatory mechanism of BTG1 expression has not been reported so far. MicroRNAs can effectively influence tumor radiosensitivity by preventing cell cycle progression, resulting in enhancement of the cytotoxicity of radiotherapy efficacy. This study aimed to demonstrating the effects of microRNAs on the BTG1 expression and cellular radiosensitivity. The human renal carcinoma 786-O cells were treated with 5 Gy of X-rays. Expressions of BTG1 gene and miR-454-3p, which was predicted to target BTG1 by software algorithm, were analyzed by quantitative polymerase chain reaction. Protein expressions were assessed by Western blot. Luciferase assays were used to quantify the interaction between BTG1 3′-untranslated region (3′-UTR) and miR-454-3p. The radiosensitivity was quantified by the assay of cell viability, colony formation and caspase-3 activity. The expression of the BTG1 gene in 786-O cells was significantly elevated after treatments with X-ray irradiation, DMSO, or serum starvation. The up-regulation of BTG1 after irradiation reduced cellular radiosensitivity as demonstrated by the enhanced cell viability and colony formation, as well as the repressed caspase-3 activity. In comparison, knock down of BTG1 by siRNA led to significantly enhanced cellular radiosensitivity. It was found that miR-454-3p can regulate the expression of BTG1 through a direct interaction with the 3′-UTR of BTG1 mRNA. Decreasing of its expression level correlates well with BTG1 up-regulation during X-ray irradiation. Particularly, we observed that over-expression of miR-454-3p by transfection inhibited the BTG1 expression and enhanced the radiosensitivity. In addition, cell cycle analysis showed that over-expression of miR-454-3p

  4. Rad51C deficiency destabilizes XRCC3, impairs recombination and radiosensitizes S/G2-phase cells

    Energy Technology Data Exchange (ETDEWEB)

    Lio, Yi-Ching; Schild, David; Brenneman, Mark A.; Redpath, J. Leslie; Chen, David J.

    2004-05-01

    The highly conserved Rad51 protein plays an essential role in repairing DNA damage through homologous recombination. In vertebrates, five Rad51 paralogs (Rad51B, Rad51C, Rad51D, XRCC2, XRCC3) are expressed in mitotically growing cells, and are thought to play mediating roles in homologous recombination, though their precise functions remain unclear. Here we report the use of RNA interference to deplete expression of Rad51C protein in human HT1080 and HeLa cells. In HT1080 cells, depletion of Rad51C by small interfering RNA caused a significant reduction of frequency in homologous recombination. The level of XRCC3 protein was also sharply reduced in Rad51C-depleted HeLa cells, suggesting that XRCC3 is dependent for its stability upon heterodimerization with Rad51C. In addition, Rad51C-depleted HeLa cells showed hypersensitivity to the DNA cross-linking agent mitomycin C, and moderately increased sensitivity to ionizing radiation. Importantly, the radiosensitivity of Rad51C-deficient HeLa cells was evident in S and G{sub 2}/M phases of the cell cycle but not in G{sub 1} phase. Together, these results provide direct cellular evidence for the importance of human Rad51C in homologous recombinational repair.

  5. The influence of gender- and age-related differences in the radiosensitivity of hematopoietic progenitor cells detected in steady-state human peripheral blood

    International Nuclear Information System (INIS)

    To investigate the importance of gender and aging on the individual radiosensitivity of lineage-committed myeloid hematopoietic stem/progenitor cells (HSPCs) detected in mononuclear cells (MNCs) of steady-state human peripheral blood (PB), the clonogenic survival of HPCs, including colony-forming unit-granulocyte macrophage; burst-forming unit-erythroid; colony-forming unit-granulocyte-erythroid-macrophage-megakaryocyte cells derived from MNCs exposed to 0.5 Gy and 2 Gy X-irradiation were estimated. MNCs were prepared from the buffy-coats of 59 healthy individual blood donors. The results showed that large individual differences exist in the number of HSPCs, as well as in the surviving fraction of cells. Furthermore, the number of progenitor cells strongly correlated with their surviving fraction, suggesting that the radiosensitivity of hematopoietic progenitor cells decreases with the number of cells in the 105 cells population. A statistically significant negative correlation was observed between the surviving fraction observed at a dose of 0.5 Gy and the age of an individual, however, none of these correlations were observed after 2 Gy irradiation. No statistically significant difference was observed in individual radiosensitivity between males and females at either radiation dose. The present results indicated a correlation between the individual responsiveness of HSPCs to ionizing irradiation, especially to low dose irradiation, and aging. (author)

  6. Heat shock transcription factor1gene silenced with RNAi to enhance radio-sensitivity of cervical carcinoma cell

    International Nuclear Information System (INIS)

    In order to suppress HSF1 gene expression using RNA interference technique and explore the changes of the radiation sensitivity of cervical carcinoma cells, HSF1-pSilencer2.1-U6neo for siRNA expression was transfected into cervical carcinoma cells by lipofectamine. HSF1mRNA expression was detected by real time poly- merase chain reaction and flow cytometry was employed to evaluate HSFlprotein expression. In addiction, the radiation sensitivity of cervical carcinoma cells was assessed by clone forming assay. The results show that HSF1mRNA expression of the cells transfected HSF1A-pSilencer2.1-U6neo descends obviously compared with control. Mean- while the radiation sensitivity of Hela cells increases with the descension of HSF1 gene expression. Experiment has been confirmed that siRNA plasmid expression vector HSF1A-pSilencer2.1-U6neo successfully suppresses HSF1gene expression. Plasmid expression vector of HSF1 gene siRNA can be use to enhance the radio-sensitivity of cervical carcinoma cells and may be used as a powerfully adjunct method for conventional radiotherapy. (authors)

  7. Contribution to some radiobiological aspects of the investigation of radiosensitizers of hypoxic cells. 4

    International Nuclear Information System (INIS)

    Radiosensitizing effect of metronidazole (Entizol, Polfa, Poland) was tested on an experimental model of ischaemized bone marrow. The changes of bone marrow cellularity were recorded after whole-body irradiation of rats protected with abdomen compression during irradiation. With an increasing dose of irradiation proportional and significant decrease of nuclear elements in bone marrow occurred the third day after irradiation. Metronidazole administered to unprotected rats (without compression) did not show any effect. The abdomen compression led to a pronounced radioprotection but metronidazole administration reduced this effect significantly. Ischaemization of the lower half of rat body produced on the level of bone marrow cellularity the protection corresponding to DRF (dose reduction factor) = 1.96 the third day after irradiation. DRF value decreased to 1.52 by metronidazole application which corresponds to ER (enhancement ratio) = 1.29. (author)

  8. The influence of cell kinetics on the radiosensitivity of Down's syndrome lymphocytes

    International Nuclear Information System (INIS)

    In agreement with previous work, [60Co]γ-irradiation shortly after phytohemagglutinin (PHA) stimulation, induces higher frequencies of chromosomal aberrations in trisomy 21 lymphocytes compared to normal controls. However, equal frequencies of chromatid aberrations are induced in fully-stimulated trisomy 21 and normal lymphocytes by irradiation during G2. We have observed that trisomic lymphocytes respond more rapidly to PHA stimulation than normal lymphocytes. Furthermore, we have observed that chromosomal radiosensitivity increases as a function of time after PHA stimulation in normal lymphocytes. When normal lymphocytes are irradiated 8 h after PHA stimulation, the frequencies of chromosomal aberrations induced are comparable to those induced in trisomy 21 lymphocytes irradiated 30 min after PHA stimulation. (orig.)

  9. The occurrence of recruitment supported from the finding of an increase in radiosensitivity of quiescent cells in solid tumors after fractionated irradiation with X-rays

    International Nuclear Information System (INIS)

    We examined the behavior of quiescent cells in solid tumors irradiated twice at various intervals with X-rays, using our recently developed method for selectively detecting the response of quiescent cells in solid tumors. To determine the labeling indices of tumors at the second irradiation, each mouse group included mice that were continuously administered BrdU until just before the second irradiation using mini-osmotic pumps which had been implanted before the first irradiation. Radiosensitivity of total tumor cells at the second irradiation decreased in proportion to the increase in interval time. However, radiosensitivity of quiescent cells was raised with increase in the interval time. In addition, the labeling index at the second irradiation was higher than that at the first irradiation. These findings supported the occurrence of recruitment from quiescent to proliferating state during fractionated irradiation. (author)

  10. Radiosensitizing effect of Chitosan on HeLa and LN 18 brain tumor cells exposed to electron beam radiation

    International Nuclear Information System (INIS)

    Chitosan has been widely used for multiple applications because it is a non-toxic biocompatible, biodegradable, and adsorptive material. A previous study has shown that low-molecular-weight chitosan (LMWC) exerts a cytotoxic effect on oral cancer cells. Although a higher concentration of LMWC in comparison to cisplatin was needed in order to kill cancer cells, it was relatively less cytotoxic to non-cancer cells. Some of the well known anticancer drugs have the property of sensitizing the cell to radiation, which will be more applicable during combination therapy of cancer. The present study was undertaken to find the radiosensitizing effect of chitosan on Hela and Brain tumor (LN18) cells against electron beam radiation (EBR). Both the cancer cell lines, Hela and LN 18 were treated with different concentration of chitosan (50 and 100 μg/ml) pre and post exposure to 4 Gy EBR. The percentage of cell viability, percentage of apoptosis and ssDNA damage in the treated cells were assessed by MTT assay, DNA diffusion assay and comet assay respectively. The obtained results showed 62.1315.08 and 65.2412.45 percent Hela and LN 18 viable cells at 24 hour after the exposure to 4 Gy EBR. The percentage of viability was found to be decreased in cells exposed to EBR in the presence of chitosan. Supporting to this, percentage of apoptotic cells was found to be more in treated groups (28.1314.34 and 25.1313.76) when compared with control (23.1911.07 and 20.7914.86). Treatment of HeLa and LN18 before and after the exposure of EBR showed significantly (P<0.05) more frequency of micronucleus and % of DNA damage than the 4 Gy EBR control group. These results conclude the sensitizing effect of chitosan on cancer cell line against EBR exposure. (author)

  11. Radiosensitivity of pimonidazole-unlabelled intratumour quiescent cell population to γ-rays, accelerated carbon ion beams and boron neutron capture reaction.

    OpenAIRE

    Masunaga, S; Sakurai, Y.; Tanaka, H.; Hirayama, R; Matsumoto, Y; Uzawa, A; Suzuki, M.; Kondo, N; Narabayashi, M.; Maruhashi, A; Ono, K.

    2013-01-01

    [Objectives] To detect the radiosensitivity of intratumour quiescent (Q) cells unlabelled with pimonidazole to accelerated carbon ion beams and the boron neutron capture reaction (BNCR). [Methods] EL4 tumour-bearing C57BL/J mice received 5-bromo-2′-deoxyuridine (BrdU) continuously to label all intratumour proliferating (P) cells. After the administration of pimonidazole, tumours were irradiated with γ-rays, accelerated carbon ion beams or reactor neutron beams with the prior administration of...

  12. Enhancement of radiosensitivity by topoisomerase II inhibitor, amrubicin and amrubicinol, in human lung adenocarcinoma A549 cells and kinetics of apoptosis and necrosis induction

    OpenAIRE

    Hayashi, Sachiko; Hatashita, Masanori; Matsumoto, Hideki; Shioura, Hiroki; KITAI, Ryuhei; Kano, Eiichi

    2006-01-01

    The effects of amrubicin (AMR) and its activemetabolite, amrubicinol (AMROH), on the sensitivity ofhuman lung adenocarcinoma A549 cells to ionizing radiationwere investigated in vitro. Further, the kinetics of apoptosisand necrosis induction were also analyzed. The cytocidalefftcts of X-ray irradiation on A549 cells resulted in a lowlevel of radiosensitivity with a D value of 12 Gy. The slopesof the survival curves in the exponential phase were plottedon semilogarithmic paper for radiation co...

  13. A rapid-mixing comparison of the mechanisms of radiosensitization by oxygen and misonidazole in CHO cells

    International Nuclear Information System (INIS)

    The mechanisms of hypoxic cell radiosensitization by oxygen and by the 2-nitroimidazole chemical sensitizer, misonidazole, were studied in CHO cells using rapid-mixing techniques. Both agents display a dose response of sensitivity in steady-state experiments which is satisfactorily fitted by a K function with maximum enhancement ratios (ER) of about 2.8. Rapid-mixing experiments demonstrated that oxygen sensitization in these cells is complete within about 10 msec even at concentrations as low as 2.6% oxygen, with no evidence for two time-resolved components as had been reported with V79 cells. Full sensitivity persists for at least 165 msec following an 8.4-fold dilution into hypoxic medium. No large temperature dependence was observed in the range 4 to 370C. Partial development of sensitization by misonidazole also occurs very quickly, within 25 msec with a 10mM drug concentration, but only to an ER of about 1.7, much below the level observed after many minutes incubation (approx.2.5) even at ice temperature. This development, too, has a very weak temperature dependence. It is suggested that although uptake of the drug is rapid, probably occurring by passive diffusion, an additional mechanism not involving gross metabolism and operating on the time scale of seconds to minutes is required to produce maximal sensitization in these cells

  14. The primary study of the radiosensitive effect on the H460 cell line by human lactotransferrin high expression in vitro

    International Nuclear Information System (INIS)

    Objective: To investigate the possible radiosensitive effect of human Lactotransferrin (hLF) high expression in lung cancer cell, we hereby constructed and transfected a recombinant vector pBC1 containing exogenous hLF gene. Methods: Firstly the recombinant plasmid pBC1-hLF was transferred into H460 and the hLF expression was evaluated by western blotting. Then we test the cell viability, apoptosis and clone formation after radiation along with the standard hLF treatment control. Results: The results showed that the hLF gene had been successfully transfect into H460 cells and hLF high expression can reduce the clone formation after radiation (P<0.01), and inhibit the cell proliferation with induced apoptosis (P<0.01). And the sensitization ratio of hLF treated and pBC1-hLF transfected were 1.29, 1.59. Conclusion: Our primary data shows that hLF high expression can radio sensitize the H460 cell in vitro. (authors)

  15. Radiosensitivity of squamous cell carcinoma metastases to the neck assessed by immunocytochemical profiling of fine-needle aspiration biopsy cell specimens: A pilot study

    International Nuclear Information System (INIS)

    Purpose: To assess radiosensitivity of neck metastases of squamous cell carcinoma of the head and neck (SCCHN) by immunocytochemical profiling of fine-needle aspiration biopsy (FNAB) cell specimens. Patients and methods: Immunocytochemical reactions to p53, cyclin D1, stefin A and Ki-67 were determined in FNAB cell samples of neck metastases from 21 patients treated with concomitant chemoradiotherapy and correlated to clinical characteristics and response to therapy. Results: Six (28.6%), eight (38.1%), 15 (71.4%) and nine (42.9%) FNAB cell samples were classified as p53, cyclin D1, stefin A and Ki-67 positive, respectively. Statistically significant predictors of favorable nodal response to chemoradiation were p53 (P = 0.025) and cyclin D1 (cytoplasmic fraction, P = 0.048) negativity and Ki-67 positivity (P = 0.045). Regional recurrence correlated with low Ki-67 immunoreactivity. A favorable profile of cyclin D1 and Ki-67 (one or both of the two) further improved the predictive strength of these markers. Conclusions: FNAB is a non-invasive, simple and cheap procedure, which could serve simultaneously for diagnostic purposes and for radiosensitivity testing. Immunocytochemical determination of cyclin D1 and Ki-67 in FNAB cell samples from neck metastases of SCCHN seems to be a valuable marker for predicting regional response to radiotherapy and might assist when deciding on appropriate primary therapy.

  16. Knock-down of hypoxia-induced carbonic anhydrases IX and XII radiosensitizes tumor cells by increasing intracellular acidosis

    Directory of Open Access Journals (Sweden)

    Jérôme eDoyen

    2013-01-01

    Full Text Available The relationship between acidosis within the tumor microenvironment and radioresistance of hypoxic tumor cells remains unclear. Previously we reported that hypoxia-induced carbonic anhydrases CAIX and CAXII constitute a robust pHi-regulating system that confers a survival advantage on hypoxic human colon carcinoma LS174Tr cells in acidic microenvironments. Here we investigate the role of acidosis, CAIX and CAXII knock-down in combination with ionizing radiation. Fibroblasts cells (-/+ CAIX and LS174Tr cells (inducible knock-down for ca9/ca12 were analyzed for cell cycle phase distribution and survival after irradiation in extracellular pHo manipulations and hypoxia (1% O2 exposure. Radiotherapy was used to target ca9/ca12-silenced LS174Tr tumors grown in nude mice. We found that diminishing the pHi-regulating capacity of fibroblasts through inhibition of NHE-1 sensitize cells to radiation-induced cell death. Secondly, the pHi-regulating function of CAIX plays a key protective role in irradiated fibroblasts in an acidic environment as accompanied by a reduced number of cells in the radiosensitive phases of the cell cycle. Thirdly, we demonstrate that irradiation of LS174Tr spheroids, silenced for either ca9 or both ca9/ca12, showed a respective 50% and 75% increase in cell death as a result of a decrease in cell number in the radioresistant S phase and a disruption of CA-mediated pHi regulation. Finally, LS174Tr tumor progression was strongly decreased when ca9/ca12 silencing was combined with irradiation in vivo. These findings highlight the combinatory use of radiotherapy with targeting of the pHi-regulating carbonic anhydrases as an anti-cancer strategy.

  17. Effects of serum starvation on radiosensitivity, proliferation and apoptosis in four human tumor cell lines with different p53 status

    International Nuclear Information System (INIS)

    Purpose: The effects of serum starvation on radiation sensitivity, cell proliferation and apoptosis were investigated with particular consideration of the p53 status. Material and Methods: Four human tumor cell lines, Be11 (melanoma, p53 wild-type), MeWo (melanoma, p53 mutant), 4197 (squamous cell carcinoma, p53 wild-type) and 4451 (squamous cell carcinoma, p53 mutant), were used. After the cells had been incubated in starvation medium (0.5% FCS) for 1-6 days, changes in cell cycle distribution, induction of apoptosis and necrosis, and changes in radiation sensitivity were assessed by two-parameter flow cytometric measurements of DNA content/BrdU labeling, two-parameter flow cytometric measurements of DNA-dye-exclusion/Annexin V binding, and a conventional colony assay, respectively. Results: p53 wild-type cell lines showed a decrease in the BrdU labeling index and an increase in the apoptotic cell frequency in starvation medium. p53 mutant cell lines showed a decrease in the BrdU labeling index but no evidence of apoptosis. These cells went into necrosis instead. The radiation sensitivity was increased in 4451 and slightly decreased in Be11 and 4197 in starvation medium. Conclusion: These data suggest a functional involvement of p53 in starvation-induced G1-block and apoptosis in tumor cells. Altered radiosensitivity after culture in starvation medium seemed to be explained at least in part by the starvation-induced G1-block. The frequency of starvation-induced apoptosis or necrosis was not correlated with radiation sensitivity. (orig.)

  18. The Ku80 inhibition cell model in telomerase-negative tumor cell lines U2OS and its relation to telomere and radiosensitivity

    International Nuclear Information System (INIS)

    Objective: To construct the KU80 inhibition cell model by RNAi in U2OS cell and to explore the relationship between the Ku80, telomeres and radiosensitivity in telomerase-negative tumor cells. Methods: U2OS cells were transfected with the recombinant plasmids of pshRNA-K80 by the lipofectamine, and the stable transfected cell clones were selected by G418. After the selection, the cells were collected and analyzed by the flow cytometry. RT-PCR and Western blot were used to measure the expression of Ku80 and Real-time PCR was used to detect the length of telomeres. The radiosensitivity of U2OS was determined by clone formation array. Results: The transfection efficiency of the positive cell clones detected by the flow cytometry was (83.23 ±7.63)%. The inhibition rate of the Ku80 gene transcription in the cell group with recombinant plasmid was (68.09 ± 1.16)% and the inhibition rate of the Ku80 protein expression in the same group was (11.03 ± 2.45)%. The results of Real-time PCR showed that the telomere length of the cell group with recombinant plasmid (1.07 ± 0.07) was significantly shorter than that of the control group (4.42 ± 1.30, F=38.58, P<0.05) and that of the empty plasmid group (4.11 ±0.84, F=38.58, P<0.05). Compared to the control group, the telomere length of the empty plasmid group did not changed (4.42 ±0.84 vs. 4.11 ±0.84). U2OS cells with Ku80 expression suppressed had lower SF2 than that of the control cells (F=1089.61, P<0.05), and resulted in the SER of 1.47. Conclusions: The Ku80 inhibition cell model in telomerase-negative U2OS cell line is successfully established which has the shorter telomere length, and is more sensitive to radiation. Telomere shortening caused by pshRNA-of Ku80 is likely to be one of the mechanisms of radiosensitization in this kind of cell model. (authors)

  19. Radiosensitive severe combined immunodeficiency disease.

    Science.gov (United States)

    Dvorak, Christopher C; Cowan, Morton J

    2010-02-01

    Inherited defects in components of the nonhomologous end-joining DNA repair mechanism produce a T-B-NK+ severe combined immunodeficiency disease (SCID) characterized by heightened sensitivity to ionizing radiation. Patients with the radiosensitive form of SCID may also have increased short- and long-term sensitivity to the alkylator-based chemotherapy regimens that are traditionally used for conditioning before allogeneic hematopoietic cell transplantation (HCT). Known causes of radiosensitive SCID include deficiencies of Artemis, DNA ligase IV, DNA-dependent protein kinase catalytic subunit, and Cernunnos-XLF, all of which have been treated with HCT. Because of these patients' sensitivity to certain forms of chemotherapy, the approach to donor selection and the type of conditioning regimen used for a patient with radiosensitive SCID requires careful consideration. Significantly more research needs to be done to determine the long-term outcomes of patients with radiosensitive SCID after HCT and to discover novel nontoxic approaches to HCT that might benefit those patients with intrinsic radiosensitivity and chemosensitivity as well as potentially all patients undergoing an HCT. PMID:20113890

  20. Non-genetic phenomenons of radiosensitivity

    International Nuclear Information System (INIS)

    Transcription factors are activated by radiation induced DNA damage. This is followed by cell cycle regulation (cell cycle blocks and DNA repair), which influence radiosensitivity. This phenomenon is seen as a genetic effect. Proteins as transcription factors (e.g. NF-κB) are directly activated by ionizing radiation, genes coding for cytokines and growth factors are expressed and influence the radiosensitivity. Damage of the cell membrane also induces signal transduction cascades and activates genes via transcription factors, which influence radiosensitivity. The latter two phenomenons are described as non genetics and will get more and more importance in He radiobiology. (orig.)

  1. Radiosensitizers, radioprotectors, and radiation mitigators

    Directory of Open Access Journals (Sweden)

    Jayam Raviraj

    2014-01-01

    Full Text Available Radiotherapy is regarded as one of the most important therapeutic modality for the treatment of malignant lesions. This field is undergoing rapid advancements in the recent times. With the use of radiosensitizers and radioprotective agents, the course of radiotherapy has improved the sensitization of tumor cells and protection of normal cells, respectively. The aim of this paper was to critically review and analyze the available compounds used as radiosensitizers, radioprotectors, and radiation mitigators. For reviewing, the author used the electronic search for the keywords ′Radiosensitizers′, ′Radioprotectors′, ′Radiation mitigators′ on PubMed for inclusion of previously published articles and further search of reference papers on individual radiosensitizing and radioprotecting agents was done. Radiosensitizers are agents that sensitize the tumor cells to radiation. These compounds apparently promote fixation of the free radicals produced by radiation damage at the molecular level. The mechanism of action is similar to the oxygen effect, in which biochemical reactions in the damaged molecules prevent repair of the cellular radiation damage. Free radicals such as OH + are captured by the electron affinity of the radiosensitizers, rendering the molecules incapable of repair. Radioprotectors are compounds that are designed to reduce the damage in normal tissues caused by radiation. These compounds are often antioxidants and must be present before or at the time of radiation for effectiveness. Other agents, termed mitigators, may be used to minimize toxicity even after radiation has been delivered. This article tries to discuss the various aspects of radiosensitizers, radioprotectors, and radiation mitigators including the newer agents.

  2. Cellular non-protein thiol depletion and radiosensitization of hypoxic cells by nitroazole derivatives possessing and NPSH-reactive side chain

    International Nuclear Information System (INIS)

    A new class of dual-function hypoxic-cell radiosensitizers that are composed of electron-affinic nitroazole rings and thiol-reactive α,β-unsaturated carbonyl side chains were synthesized. Typically, methyl 4-(2'-nitroimidazolyl)crotonate (1) reacted with glutathione (GSH) in phosphate buffer solution to form the corresponding 1,4-addition products which have been isolated and fully characterized by spectroscopy. The same reaction took place within EMT6/KU cells with intracellular GSH to give the drug-GSH conjugates. The enhanced radiosensitizing activity of 1 on hypoxic EMT6/KU cells by alteration in both D0 and n parameters of dose-survival curve was suggested as the result of the intracellular NPSH-depletion by the common α,β-unsaturated carbonyl side chain. (author)

  3. The Biochemical Effects of the Promising Hypoxic Cell radiosensitizers KIN-804, KIN-844, KIN-806 d TX-1877 in Mice Bearing Ehrlich Ascites Carcinoma

    International Nuclear Information System (INIS)

    The existence of hypoxic cells in solid tumors is one of the important limiting factors in the local control of malignant tumors by radiation therapy. A series of new analogues of 2-nitroimidazole has been synthesized. Among these 2-nitroimidazoles, the derivatives KIN-804, KIN-806 and their analogs KIN-844, TX-1877 were selected, evaluated and compared biochemically with these of misonidazole (MISO). The radiosensitizing activity and acute toxicity of those new hypoxic cell radiosensitizer were previously established both in vitro and in vivo . The present study was design to evaluate the effect of those compounds at dose level 0.4g/kg body weight, injected alone or in combination with g-irradiation on the liver reduced glutathione content, (GSH); glucose-6-phosphate dehydrogenase (G-6-PDH); superoxide dismutase (SOD), catalase and brain acetylcholinesterase (AChE) in Swiss albino mice bearing solid Ehrlich ascites carcinoma (EAC, 2.5 x 10 cells)

  4. Growth kinetics and in vivo radiosensitivity in nude mice of two subpopulations derived from a single human small cell carcinoma of the lung

    DEFF Research Database (Denmark)

    Spang-Thomsen, M; Clerici, M; Engelholm, S A;

    1986-01-01

    The growth kinetics and the in vivo radiosensitivity of two human small cell carcinomas of the lung (SCCL) grown in nude mice were investigated. The tumors, CPH SCCL 54A and 54B, were derived by in vitro cloning of a single SCCL and were subsequently serially grown in nude mice. The growth curves...... were described according to a transformed Gompertz function, and the cell kinetics were examined by flow cytometric DNA analysis (FCM) and by the technique of labelled mitoses. The effect of single-dose irradiation was estimated by the specific growth delay calculated from the growth curves, and by the...... cell cycle distribution changes monitored by FCM. The results showed that the tumors differed in the in vivo radiosensitivity despite similarities in the growth kinetics. The results support the concept that difference in sensitivity among tumor subpopulations is an important reason for therapeutic...

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

    Science.gov (United States)

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

    2016-01-01

    Ruthenium(II) polypyridyl complexes can intercalate DNA with high affinity and prevent cell proliferation; however, the direct impact of ruthenium-based intercalation on cellular DNA replication remains unknown. Here we show the multi-intercalator [Ru(dppz)2(PIP)](2+) (dppz = dipyridophenazine, PIP = 2-(phenyl)imidazo[4,5-f][1,10]phenanthroline) immediately stalls replication fork progression in HeLa human cervical cancer cells. In response to this replication blockade, the DNA damage response (DDR) cell signalling network is activated, with checkpoint kinase 1 (Chk1) activation indicating prolonged replication-associated DNA damage, and cell proliferation is inhibited by G1-S cell-cycle arrest. Co-incubation with a Chk1 inhibitor achieves synergistic apoptosis in cancer cells, with a significant increase in phospho(Ser139) histone H2AX (γ-H2AX) levels and foci indicating increased conversion of stalled replication forks to double-strand breaks (DSBs). Normal human epithelial cells remain unaffected by this concurrent treatment. Furthermore, pre-treatment of HeLa cells with [Ru(dppz)2(PIP)](2+) before external beam ionising radiation results in a supra-additive decrease in cell survival accompanied by increased γ-H2AX expression, indicating the compound functions as a radiosensitizer. Together, these results indicate ruthenium-based intercalation can block replication fork progression and demonstrate how these DNA-binding agents may be combined with DDR inhibitors or ionising radiation to achieve more efficient cancer cell killing. PMID:27558808

  6. Radioimmunotherapy of solid tumors targeting a cell-surface protein, FZD10. Therapeutic efficacy largely depends on radiosensitivity

    International Nuclear Information System (INIS)

    Frizzled homolog 10 (FZD10) is expressed at high levels on the cell surface of almost all synovial sarcoma tissues, but is absent in most normal organs. In a previous study, yttrium-90 (90Y)-labeled anti-FZD10 antibody (MAb 92-13) showed considerable therapeutic efficacy in synovial sarcoma cell-bearing mice. The purpose of the present study was to elucidate the factors associated with this therapeutic efficacy of 90Y-MAb 92-13. FZD10 expression levels of SYO-1 (FZD10-overexpressing synovial sarcoma cell line) and DLD-1/FZD10 (FZD10-transfected DLD-1 cell) were determined by the cell binding assay, and their radiosensitivity was evaluated by incubation with 90Y-MAb 92-13 in vitro. Biodistribution study of indium-111 (111In)-MAb 92-13 was performed in SYO-1 and DLD-1/FZD10 tumor-bearing mice. For therapeutic studies, SYO-1 and DLD-1/FZD10 tumor-bearing mice were treated with 90Y-MAb 92-13 (100, 150, and 200 μCi), after which the change in tumor volume was measured. Immunohistochemical staining was performed on the excised tumor. Expression level of FZD10 on DLD-1/FZD10 was much greater than that on SYO-1. The accumulation of 111In-MAb 92-13 was much higher in DLD-1/FZD10 tumor-bearing mice than in SYO-1 tumor-bearing mice (49.0±4.2 and 22.0±4.5% ID/g, respectively, at 48 h after administration). In SYO-1 tumor, substantial tumor size reduction was observed in all mice treated with 90Y-MAb 92-13 (tumor volume decreased to less than 0.1 cm3 at 11 days after treatment) and tumor regrowth was not observed in most of them. In contrast, only slow progression was observed in DLD-1/FZD10 tumor. When incubated with 90Y-MAb 92-13, high radioactivity was needed to damage DLD-1/FZD10. Immunohistochemical study indicated apoptosis of SYO-1 tumor. The therapeutic efficacy of radioimmunotherapy (RIT) seems to largely depend on the tumor radiosensitivity. (author)

  7. Radiosensitivities of sensitized lymphocytes

    International Nuclear Information System (INIS)

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

  8. Adenovirus-mediated expression of UHRF1 reduces the radiosensitivity of cervical cancer HeLa cells to γ-irradiation

    Institute of Scientific and Technical Information of China (English)

    Xin-li LI; Qing-hui MENG; Sai-jun FAN

    2009-01-01

    Aim:An in vitro study was carried out to determine the effect of UHRF1 overexpression on radiosensitivity in human cervical cancer HeLa ceUs using adenovirus-mediated UHRF1 gene transfer (Ad5-UHRF1). Methods: Cell survival was evaluated using the clonogenic survival assay and the MTT assay; apoptosis and cell cycle distribution were monitored by flow cytometry. Protein levels were measured by Western blotting. Silencing XRCC4 expression was performed by transfection of small interfering RNA (siRNA).Results: Increased expression of UHRF1 by AdS-UHRF1 significantly reduced the radiosensitivity of HeLa cells. The UHRF1-mediated radioresistance was correlated with increased DNA repair capability and increased expression of the DNA damage repair protein, XRCC4. Knocking down XRCC4 expression in the cells using XRCC4 siRNA markedly reduced the UHRFl-mediated radioresistance. Conclusion: These results provide the first evidence for revealing a functional role of UHRF1 in human cervical cancer cells as a negative regulator of radiosensitivity.

  9. Examining the effect of gene reduction in miR-95 and enhanced radiosensitivity in non-small cell lung cancer.

    Science.gov (United States)

    Ma, W; Ma, C-N; Li, X-D; Zhang, Y-J

    2016-02-01

    MicroRNAs (miRNAs) represent a group of novel therapeutic small molecules involved in the management of lung cancer treatment. Our study aims to investigate the potential role of miRNAs in the treatment of non-small cell lung cancer (NSCLC). Human miRNA microarray was performed in 60 recurrent NSCLC patient tissue samples following radiotherapy and their adjacent normal tissues. miRNA profiling results were validated using quantitative real-time PCR. Inner cell radiosensitivity and endogenous miRNA expression was determined by colony-formation assay and RT-PCR. We determined the effect of miRNA on cell proliferation, survival and metastasis; tumor xenografts were taken to identify the presence of miRNA in vivo. miRNA panel results indicated that a total of 14 miRNAs were differentially expressed in the recurrent NSCLC samples. In our study, miRNA-95 was highly overexpressed in recurrent NSCLC cells. Knockdown of miRNA-95 expression increased the radiosensitivity of NSCLC, promoted tumor cell apoptosis and decreased cellular proliferation. In vivo assays demonstrated reduced tumor growth and resistance to radiation in tumor xenografts by downregulating miRNA-95. Our study demonstrated a potential therapeutic measure of miRNA-95 as a radiosensitive marker for the treatment of non-small lung cancer. PMID:26915403

  10. The radio-sensitivity effect of E1A gene transfected by PEI on colon carcinoma cell in vitro

    International Nuclear Information System (INIS)

    As a neotype nonviral vector, (Polyethylenimine, PEI) has been studied in gene transfection experiment. This study was investigated the growth inhibition and radio-sensitizing effect of E1A gene transfected by PEI on human colon carcinoma cell in vitro. The PSV-E1A recombinant plasmid, which was designed for high-level expression of E1A gene in a variety of eukaryotic cell lines, was transfected into SW480 cells by PEI. The transfection was confirmed by RT-PCR and G418 was used to get colon carcinoma cells stably expressed E1A gene. The cell growth curve were investigated to observe the growth inhibition induced by E1A gene. The redistributions of cell cycle were analyzed by flow cytometry. Cells before and after transfection were treated with irradiation, then the changes of radiation-sensitivity were tested by MTT assay after 24 h meanwhile the expression of HER-2 gene in SW480 cells before and after transfection was detected by western-blot. As results, (1) the colon carcinoma cells expressed E1A gene was confirmed by G418. (2) The result of RT-PCR demonstrated that PEI could transfect plasmid psv-E1A and the cells could stably express E1A gene. (3) Flow cytometry revealed that E1A gene transfected into human colon carcinoma cell could induce S stage suppression (p<0.001) and G2/M stage arrest (p<0.001). (4) Compared with the Non-transfected cells, the E1A-transfected cells (SW480-E1A cells) grew slowly observed by MTT assay which was used to get the absorbance of SW480 cell and SW480-E1A cell. (5) The radiation-sensitivity of SW480 cells transfected with E1A gene was up-regulated obviously (p<0.001). (6) The E1A gene obviously down-regulated HER-2 protein expression in colon carcinoma cells. Anyway, PEI can transfect plasmid psv-E1A gene which can significantly inhibit the growth rate of SW480 cell. Moreover, it also obviously enhanced the cell sensitivity to irradiation. (authors)

  11. Radiosensitivity of mouse haemopoietic stem cells that form colonies 8 and 12 days after transplantation of bone marrow cells

    International Nuclear Information System (INIS)

    The method of macro- and microcolonies was used to study the radiosensitivity of CFU-S that form early (8 days) and late (12 days) splenic colonies after transplantation of syngeneic bone marrow fatally exposed mice: no significant differences were found. Median lethal doses (D0) for CFU-S-8 and CFU-S-12 were 1.03 and 1.13 Gy for microtest and 0.99 and 1.116 Gy for microtest respectively

  12. Silencing of osteopontin promotes the radiosensitivity of breast cancer cells by reducing the expression of hypoxia inducible factor 1 and vascular endothelial growth factor

    Institute of Scientific and Technical Information of China (English)

    YANG Li; ZHAO Wei; ZUO Wen-shu; WEI Ling; SONG Xian-rang; WANG Xing-wu; ZHENG Gang; ZHENG Mei-zhu

    2012-01-01

    Background Osteopontin (OPN) is a secreted phosphoglycoprotein (SSP) that is overexpressed in a variety of tumors and was regarded as a molecular marker of tumors.In this study,we intended to demonstrate the role of OPN in human breast cancer cell line MDA-MB-231.Methods Recombinant plasmid expressing small interfering RNA (siRNA) specific to OPN mRNA was transfected into MDA-MB-231 cells to generate the stable transfected cell line MDA-MB-343,and the empty plasmid tansfected cells (MDA-MB-neg) or wildtype MDA-MB-231 cells were used as control cells respectively.Expression of OPN,hypoxia inducible factor-1 (HIF-1) and vascular endothelial growth factor (VEGF) proteins was analyzed by Western blotting analysis.The radiosensitivity of cells was determined by detecting cell apoptosis,cell proliferation and cell senescence.Results HIF-1 and VEGF proteins in MDA-MB-343 cells were significantly downregulated upon the efficient knockdown of OPN expression under either hypoxia or normoxia environment.Moreover,expression of OPN protein was upregualted upon hypoxic culture.Stable OPN-silencing also decreased cell invasion,increased cell apoptosis and cell senescence,as well as reduced clonogenic survival,resulting in increase radiation tolerance.Conclusions Suppression of OPN gene expression can enhance radiosensitivity and affect cell apoptosis in breast cancer cells.OPN seems to be an attractive target for the improvement of radiotherapy.

  13. Enhancement of the radiation-lethal effect of hypoxic cancer cells by some nitroheterocyclic compounds. Part of a coordinated programme on the improvement of radiotherapy of cancer using modifiers of radiosensitivity of cells

    International Nuclear Information System (INIS)

    The possibilities to enhance the lethal effect of ionizing radiation on hypoxic cells by electron-affinic compounds have stimulated the investigations for finding new chemicals with radiobiological and pharmacological features as adequate as possible. On the other hand, the experimental studies and clinical trials had shown that the aerobic toxicity seems to be the major limiting factor in the use of large doses of radiosensitizers required to achieve significant therapeutic efficiency. The investigations in the present paper were attempted to join these two main directions of research and comprised the syntheses of new nitroheterocyclic compounds with potential radiosensitization properties and the knowledge of biochemical alterations involved in the producing of aerobic toxicity of radiosensitizers aiming to find practical solutions to enhance the efficiency of radiotherapy. Several newly synthesized compounds were tested for their radiosensitizing effect. The experiments carried out on hypoxic cells V 79 showed that only 1-(hydroxyethyl-2'-phosphate)-2-methyl-5-nitroimidazole, dipotassium salt displayed an enhancement ratio of 1.17 (at 8 mM), but lower than in case of parent compound, metronidazole (enhancement ratio = 1.53). It was shown that hypoxic cell radiosensitizers interfere with the cellular energy metabolism. These interferences were found dependent on the electron affinity of drugs. In addition, those radiosensitizers producing a decrease in oxygen consumption caused a supplementary oxygenation of both normal and tumour tissues. It is concluded that the improvement of therapeutic efficiency of radiosensitizers by reducing their aerobic toxicity might be achieved by diminishing their effects on the energy metabolism or by the stimulation of this metabolism and restoration of tissue redox equilibrium

  14. Radiosensitizing effects of perfluorochemicals

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, Takeo; Harima, Keizo; Tanaka, Yoshimasa

    1988-10-01

    Malignant neoplasms are often refractory to radiotherapy because they contain areas of hypoxic cells that tolerate irradiation, reducing the effect of the treatment. If these areas of hypoxic cells can be oxygenated, the effect of radiotherapy is expected to be enhanced. Hyperbaric oxygen theray was devised in the 1950s, and the radiosensitizing agent Misonidazole was developed in 1970. However, neither produced satisfactory clinical effects in radiotherapy of tumors. In this study, hypoxic cells in a solid tumor were efficiency oxygenated by the use of perfluorochemicals (PFC) developed as artificial blood with carbogen gas (CG), and the anti-tumor effect of irradiation was enhanced. In C3H mice bearing RIF-1 tumor, the mean oxygen pressure increased to 79.8 mmHg in those treated with PFC and CG as compared with 12.9 mmHg in the controls, and the does modification factor in irradiation of these mice was TCD/sub 50/ 1.47. PFC is currently under clinical trials, and we also noted effective oxygenation of tumors. These findings indicate the usefulness of PFC as a radiosensitizing agent.

  15. Double targeting of Survivin and XIAP radiosensitizes 3D grown human colorectal tumor cells and decreases migration

    International Nuclear Information System (INIS)

    Background and purpose: In the present study, we aimed to investigate the effect of single and double knockdown of the inhibitor of apoptosis proteins (IAP) Survivin and X-linked IAP (XIAP) on three-dimensional (3D) clonogenic survival, migration capacity and underlying signaling pathways. Materials and methods: Colorectal cancer cell lines (HCT-15, SW48, SW480, SW620) were subjected to siRNA-mediated single or Survivin/XIAP double knockdown followed by 3D colony forming assays, cell cycle analysis, Caspase activity assays, migration assays, matrigel transmigration assays and Western blotting (Survivin, XIAP, Focal adhesion kinase (FAK), p-FAK Y397, Akt1, p-Akt1 S473, Extracellular signal-regulated kinase (ERK1/2), p-ERK1/2 T202/Y204, Glycogen synthase kinase (GSK)3β, p-GSK3β S9, nuclear factor (NF)-κB p65). Results: While basal cell survival was altered cell line-dependently, Survivin or XIAP single and Survivin/XIAP double knockdown enhanced cellular radiosensitivity of all tested cancer cell lines grown in 3D. Particularly double knockdown conditions revealed accumulation of cells in G2/M, increased subG1 fraction, elevated Caspase 3/7 activity, and reduced migration. Intracellular signaling showed dephosphorylation of FAK and Akt1 upon Survivin and/or Survivin/XIAP silencing. Conclusions: Our results strengthen the notion of Survivin and XIAP to act as radiation resistance factors and further indicate that these apoptosis-regulating proteins are also functioning in cell cycling and cell migration

  16. Radio-sensitivity of callus and cell cultures, and RAPD characterization of variants in banana [Musa spp.

    International Nuclear Information System (INIS)

    Although bananas and plantains are one of the most important fruit crops, gearing up the breeding programmes for these has always remained the most difficult task due to several inherent problems such as parthenocarpy, barriers in obtaining viable seeds and long life cycle etc. In this regard, incorporation of in vitro techniques such as shoot-tip / cell cultures along with conventional as well as non-conventional methods of genetic improvement is of utmost importance, especially in those vegetatively propagated species with long crop cycle and low in vivo proliferation rate. In order to understand the radio-sensitivity, the callus and cell cultures of banana were exposed to differential doses of gamma-rays. Growth of the callus cultures reduced with increasing dose of gamma-rays. Similar trend was noticed in irradiation of cell suspensions also where a dose of 40 Gy and more was completely lethal. The experience gained from previous and present experiments has yielded optimization of the procedures for gamma-irradiation and subsequent handling of banana in vitro cultures. The RAPD analysis of the selected variants was unable to detect adequate polymorphism, and further experimentation in these regards is being done. (author)

  17. In vitro studies on radiosensitization effect of glucose capped gold nanoparticles in photon and ion irradiation of HeLa cells

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Harminder; Pujari, Geetanjali [Radiation Biology Group, Inter University Accelerator Centre, Post Box 10502, New Delhi 110067 (India); Semwal, Manoj K. [Army Hospital (R and R), Delhi Cantonment, New Delhi 110010 (India); Sarma, Asitikantha [Radiation Biology Group, Inter University Accelerator Centre, Post Box 10502, New Delhi 110067 (India); Avasthi, Devesh Kumar, E-mail: dka@iuac.res.in [Radiation Biology Group, Inter University Accelerator Centre, Post Box 10502, New Delhi 110067 (India)

    2013-04-15

    Highlights: ► Glucose capped gold nanoparticles (Glu-AuNPs) are synthesized for internalization in HeLa cells (cervical cancer cells). ► Internalization of Glu-AuNPs in HeLa cells is confirmed by cross section TEM of cells. ► Irradiation (by C ion or γ-rays) of HeLa cells with internalized Glu-AuNPs results in enhanced radiosensitization. ► There is about 30% reduction in radiation dose for 90% cell killing of HeLa cells, when internalized by Glu-AuNPs. ► The enhanced radiosensitization due to Glu-AuNPs is of interest for researchers in nanobiotechnology and radiation biology. -- Abstract: Noble metal nanoparticles are of great interest due to their potential applications in diagnostics and therapeutics. In the present work, we synthesized glucose capped gold nanoparticle (Glu-AuNP) for internalization in the HeLa cell line (human cervix cancer cells). The capping of glucose on Au nanoparticle was confirmed by Raman spectroscopy. The Glu-AuNP did not show any toxicity to the HeLa cell. The γ-radiation and carbon ion irradiation of HeLa cell with and without Glu-AuNP were performed to evaluate radiosensitization effects. The study revealed a significant reduction in radiation dose for killing the HeLa cells with internalized Glu-AuNPs as compared to the HeLa cells without Glu-AuNP. The Glu-AuNP treatment resulted in enhancement of radiation effect as evident from increase in relative biological effectiveness (RBE) values for carbon ion irradiated HeLa cells.

  18. The female guinea pig, a useful model for the genetic hazard of radiation in man; preliminary results on germ cell radiosensitivity in foetal, neonatal and adult animals

    International Nuclear Information System (INIS)

    A comparison was made of the radiosensitivities of the resting oocyte of guinea pig in its two different states, the 'large' resting and 'contracted' oocyte, also extending the investigations to the radiosensitivity of the female germ cells at earlier stages during intrauterine life. Irradiation induced a dose-dependent decrease in the total number of oocytes, and this effect was more pronounced in animals irradiated as adults (target cells: contracted resting oocytes). Our results also suggested that the LD50 of the large guinea pig resting oocyte should be around 4 Gy, a value similar to that obtained recently for the equivalent human oocyte. This confirms the high radioresistance of the guinea pig oocyte and the consequent suitability of this species for further detailed studies in relation to genetic hazards in man. (author)

  19. Knockdown of TC-1 enhances radiosensitivity of non-small cell lung cancer via the Wnt/β-catenin pathway

    Directory of Open Access Journals (Sweden)

    Dapeng Wu

    2016-04-01

    Full Text Available Thyroid cancer 1 (TC-1, C8ofr4 is widely expressed in vertebrates and associated with many kinds of tumors. Previous studies indicated that TC-1 functions as a positive regulator in the Wnt/β-catenin signaling pathway in non-small cell lung cancer (NSCLC. However, its exact role and regulation mechanism in radiosensitivity of NSCLC are still unclear. The expression level of TC-1 was measured by qRT-PCR and western blot in NSCLC cell lines. Proliferation and apoptosis of NSCLC cells in response to TC-1 knockdown or/and radiation were determined by MTT assay and flow cytometry, respectively. The activation of the Wnt/β-catenin signaling pathway was further examined by western blot in vitro and in vivo. Compared to TC-1 siRNA or radiotherapy alone, TC-1 silencing combined with radiation inhibited cell proliferation and induced apoptosis in NSCLC cell lines by inactivating of the Wnt/β-catenin signaling pathway. Furthermore, inhibition of the Wnt/β-catenin signaling pathway by XAV939, a Wnt/β-catenin signaling inhibitor, contributed to proliferation inhibition and apoptosis induction in NSCLC A549 cells. Combinative treatment of A549 xenografts with TC-1 siRNA and radiation caused significant tumor regression and inactivation of the Wnt/β-catenin signaling pathway relative to TC-1 siRNA or radiotherapy alone. The results from in vitro and in vivo studies indicated that TC-1 silencing sensitized NSCLC cell lines to radiotherapy through the Wnt/β-catenin signaling pathway.

  20. Down-Regulation of EBV-LMP1 Radio-Sensitizes Nasal Pharyngeal Carcinoma Cells via NF-κB Regulated ATM Expression

    OpenAIRE

    Xiaoqian Ma; Lifang Yang; Lanbo Xiao; Min Tang; Liyu Liu; Zijian Li; Mengyao Deng; Lunquan Sun; Ya Cao

    2011-01-01

    BACKGROUND: The latent membrane protein 1 (LMP1) encoded by EBV is expressed in the majority of EBV-associated human malignancies and has been suggested to be one of the major oncogenic factors in EBV-mediated carcinogenesis. In previous studies we experimentally demonstrated that down-regulation of LMP1 expression by DNAzymes could increase radiosensitivity both in cells and in a xenograft NPC model in mice. RESULTS: In this study we explored the molecular mechanisms underlying the radiosens...

  1. The radiosensitizing effect of Ku70/80 knockdown in MCF10A cells irradiated with X-rays and p(66)+Be(40) neutrons

    International Nuclear Information System (INIS)

    A better understanding of the underlying mechanisms of DNA repair after low- and high-LET radiations represents a research priority aimed at improving the outcome of clinical radiotherapy. To date however, our knowledge regarding the importance of DNA DSB repair proteins and mechanisms in the response of human cells to high-LET radiation, is far from being complete. We investigated the radiosensitizing effect after interfering with the DNA repair capacity in a human mammary epithelial cell line (MCF10A) by lentiviral-mediated RNA interference (RNAi) of the Ku70 protein, a key-element of the nonhomologous end-joining (NHEJ) pathway. Following irradiation of control and Ku-deficient cell lines with either 6 MV X-rays or p(66)+Be(40) neutrons, cellular radiosensitivity testing was performed using a crystal violet cell proliferation assay. Chromosomal radiosensitivity was evaluated using the micronucleus (MN) assay. RNAi of Ku70 caused downregulation of both the Ku70 and the Ku80 proteins. This downregulation sensitized cells to both X-rays and neutrons. Comparable dose modifying factors (DMFs) for X-rays and neutrons of 1.62 and 1.52 respectively were obtained with the cell proliferation assay, which points to the similar involvement of the Ku heterodimer in the cellular response to both types of radiation beams. After using the MN assay to evaluate chromosomal radiosensitivity, the obtained DMFs for X-ray doses of 2 and 4 Gy were 2.95 and 2.66 respectively. After neutron irradiation, the DMFs for doses of 1 and 2 Gy were 3.36 and 2.82 respectively. The fact that DMFs are in the same range for X-rays and neutrons confirms a similar importance of the NHEJ pathway and the Ku heterodimer for repairing DNA damage induced by both X-rays and p(66)+Be(40) neutrons. Interfering with the NHEJ pathway enhanced the radiosensitivity of human MCF10A cells to low-LET X-rays and high-LET neutrons, pointing to the importance of the Ku heterodimer for repairing damage induced by both

  2. Chromosomes, cancer and radiosensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Samouhos, E.

    1983-08-01

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

  3. Chromosomes, cancer and radiosensitivity

    International Nuclear Information System (INIS)

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

  4. PARP1 inhibition radiosensitizes HNSCC cells deficient in homologous recombination by disabling the DNA replication fork elongation response.

    Science.gov (United States)

    Wurster, Stephanie; Hennes, Fabian; Parplys, Ann C; Seelbach, Jasna I; Mansour, Wael Y; Zielinski, Alexandra; Petersen, Cordula; Clauditz, Till S; Münscher, Adrian; Friedl, Anna A; Borgmann, Kerstin

    2016-03-01

    There is a need to develop new, more efficient therapies for head and neck cancer (HNSCC) patients. It is currently unclear whether defects in DNA repair genes play a role in HNSCCs' resistance to therapy. PARP1 inhibitors (PARPi) were found to be "synthetic lethal" in cancers deficient in BRCA1/2 with impaired homologous recombination. Since tumors rarely have these particular mutations, there is considerable interest in finding alternative determinants of PARPi sensitivity. Effectiveness of combined irradiation and PARPi olaparib was evaluated in ten HNSCC cell lines, subdivided into HR-proficient and HR-deficient cell lines using a GFP-based reporter assay. Both groups were equally sensitive to PARPi alone. Combined treatment revealed stronger synergistic interactions in the HR-deficient group. Because HR is mainly active in S-Phase, replication processes were analyzed. A stronger impact of treatment on replication processes (p = 0.04) and an increased number of radial chromosomes (p = 0.003) were observed in the HR-deficient group. We could show that radiosensitization by inhibition of PARP1 strongly correlates with HR competence in a replication-dependent manner. Our observations indicate that PARP1 inhibitors are promising candidates for enhancing the therapeutic ratio achieved by radiotherapy via disabling DNA replication processes in HR-deficient HNSCCs. PMID:26799421

  5. Treatment of HeLa cells with Giloe (Tinospora cordifolia meirs) increases the radiosensitivity by increasing DNA damage

    International Nuclear Information System (INIS)

    Radiotherapy is an important treatment modality and screening of phytoceuticals may enhance the clinical outcome of radiotherapy, therefore radiosensitizing activity of various guduchi (Tinospora cordifolia) extracts was studied in HeLa cells. Chromosomal aberrations were scored in HeLa cells treated with 10 μg/ml of aqueous, methanol, or methylene chloride guduchi extracts or doxorubicin before exposure to 0, 0.5, 1, 2 or 3 Gy of γ-radiation at 12, 24, 36 or 48 h post-irradiation. Irradiation of HeLa cells caused a dose dependent rise in the chromatid breaks, chromosome breaks, dicentric, centric rings, acentric fragments and total aberrations at all post-irradiation times and the dose response was linear quadratic for all types of aberrations scored. Chromatid breaks increased up to 12 h post-irradiation and declined steadily up to 48 h post-irradiation, whereas chromosome breaks, dicentric, acentric fragments and total aberrations elevated up to 24 h post-irradiation and declined thereafter. However, centric rings continued to rise steadily up to 48 h post-irradiation. Treatment of HeLa cells with aqueous, methanol or methylene chloride guduchi extract or doxorubicin before irradiation significantly enhanced various types of chromosomal aberrations and a maximum rise in the chromosome aberrations was observed in the HeLa cells treated with methylene chloride extract before irradiation when compared to other groups. Various guduchi extracts enhanced the effect of radiation in HeLa cells by increasing the molecular damage to cellular genome and their effect was similar to or even greater than doxorubicin (positive control) pretreatment, depending on the type of guduchi extract used. (author)

  6. Effects of X-ray irradiation combined with RNAi against STAT3 on radiosensitivity of human esophageal carcinoma cells

    International Nuclear Information System (INIS)

    Objective: To explore the effects of X-ray irradiation combined with RNAi against signal transducer and activator of transcription 3 (STAT3) on the radiosensitivity of human esophageal carcinoma cells. Methods: Human esophageal carcinoma cells of the line Eca-109 were cultured. Three pairs of DNA template aiming at the base sequences of the coding regions 2037-2055, 1243-1261, and 455-473 of the STAT3 mRNA were synthesized(siRNA1, siRNA2, and siRNA3), and a negative sequence was synthesized to be used as control. STAT3-siRNA positive recombinant plasmids(pRNAT-U6.1-siRNA1, pRNAT-U6.1-siRNA2, and pRNAT-U6.1-siRNA3), and a STAT3-siRNA negative recombinant plasmid (pRNAT-U6.1-negative) were thus constructed and then transfected into the cultured Eca-109 cells, which were divided into transfection reagent control group, pRNAT-U6.1-siRNA1-3 transfection groups,and pRNAT-U6.1-negative control group. The positive cell clones were screened. RT-PCR and Western blotting were used to detect the STAT3 mRNA and protein expression. The transfected Eca-109 cells were exposed to 0, 2, 4, 6, and 8 Gy of X-rays,respectively, and the survival fraction of the cells was analyzed by clone formation assay. Flow cytometry was applied to analyze the cycle arrest and cell apoptosis 4 Gy post-irradiation. Results: Agarose gel electrophoresis confirmed the successful construction of the plasmid pRNAT-U6.1-siRNA. RT-PCR and Western blotting demonstrated that the mRNA and protein expression levels of STAT3 transfected with STAT3-siRNA3 were both significantly lower than those of the control groups. At 2-8 Gy, the survival fractions of the siRNA3 group were all significantly lowered than those of the control group (t=-0.228 - -0.051, P<0.05). Flow cytometry showed that the percentage of the cell cycle G0/G1 phase and the apoptosis rate of the siRNA3 group were both significantly higher than those of the control groups at 4 Gy post-irradiation (t=-13.137-16.350, P<0.01). Conclusions: X

  7. Low Dose Hyper-radiosensitivity in Human Lung Cancer Cell Line A549 and Its Possible Mechanisms

    Institute of Scientific and Technical Information of China (English)

    Xiaofang DAI; Dan TAO; Hongge WU; Jing CHENG

    2009-01-01

    The low dose hyper-radiosensitivity (HRS) in human lung cancer cell line A549 was in-vestigated,the changes of ATM kinase,cell cycle and apoptosis of cells at different doses of radiation were observed,and the possible mechanisms were discussed.A549 cells in logarithmic growth phase were irradiated with 60Co γ-rays at doses of 0-2 Gy.Together with flow cytometry for precise cell sorting,cell survival fraction was measured by means of conventional colony-formation assay.The expression of ATM1981Ser-P protein was examined by Western blot 1 h after radiation.Apoptosis was detected by Hoechst 33258 fluorescent staining,and Annexin V-FITC/PI staining flow cytometry 24 h after radiation.Cell cycle distribution was observed by flow cytometly 6,12 and 24 h after ra-diation.The results showed that the expression of ATM1981Ser-P protein was observed at 0.2 Gy,followed by an increase at >0.2 Gy,and reached the peak at 0.5 Gy,with little further increase as the dose exceeded 0.5 Gy.Twenty-four h after radiation,partial cells presented the characteristic mor-phological changes of apoptosis,and the cell apoptosis curve was coincident with the survival curve.As compared with control group,the cell cycle almost had no changes after exposure to 0.1 and 0.2 Gy radiation (P>0.05).After exposure to 0.3,0.4 and 0.5 Cry radiation,G2/M phase arrest occurred 6 and 12 h after radiation (P<0.05),and the ratio of G2/M phase cells was decreased 24 h after radiation (P<0.05).It was concluded that A549 cells displayed the phenomenon of HRS/IRR.The mode of cell death was mainly apoptosis.The activity of ATM and cell cycle change may take an important role in HRS/IRR.

  8. No benefits of ultrafractionation in two head-and-neck cancer cell lines with different inherent radiosensitivity

    International Nuclear Information System (INIS)

    Purpose: To assess if ultrafractionation is applicable in the context of an unknown hyperradiosensitivity (HRS) status, we studied the survival and repair capacity of two tumor cell lines after irradiation with two different dose/fractionation schedules that can be used in a clinical setting. Methods and Materials: Squamous cell carcinoma cell lines SCC-3 (radioresistant) and SCC-6 (radiosensitive) were used. Survival was studied by clonogenic assay after multiple fractions of 0.5 Gy (2 fractions/day, 6-h interval) and 2 Gy (1 fraction/day) for a total dose of 8 Gy of γ-rays. The capacity to repair single-strand and double-strand breaks (SSB, DSB) was assessed by comet assay. The messenger RNA (mRNA) levels of DNA-dependent protein kinase (PK) components were analyzed by RNase protection and real-time polymerase chain reaction (PCR). Results: In both cell lines, no apparent difference was noted between the two fractionation protocols. In particular for SCC-3, the mean surviving fraction tended to be lower after 2 Gy than after 0.5 Gy fractions. In SCC-3 and SCC-6 no significant difference was observed in the repair capacity of SSB and DSB after exposure to single doses of 0.5 Gy or 2 Gy. After exposure to the same single doses, the mRNA levels of DNA-PK catalytic subunit (PKcs), Ku 70, and Ku 80 were similar. Conclusions: Our data do not support the concept of ultrafractionation, at least when using fractions of 0.5 Gy in the cell lines studied. This suggests that methods for testing HRS status in individual tumors need to be developed before the relevance of ultrafractionation can be investigated in the clinic

  9. The spectrum of in vitro radiosensitivity in four human melanoma cell lines is not accounted for by differential induction or rejoining of DNA double strand breaks

    International Nuclear Information System (INIS)

    Purpose: Radioresistance is a significant clinical problem in advanced malignant melanoma and many melanoma cell lines show a radioresistant acute x-ray survival response in vitro. Given that the DNA double strand break is the lesion most closely correlated with x-ray induced cell lethality, differences in the induction and rejoining of these lesions may account for the radioresistance of some human melanoma cell lines. Methods and Materials: The above hypothesis was tested using pulsed field gel electrophoresis to measure x-ray induced DNA double strand break induction and rejoining in four human melanoma cell lines: MM138, MM170, MM96-L and HT 144. Results: The MM138, MM170 and MM96-L cell lines were characterized in vitro by low (α(β)) ratios and board x-ray survival curve shoulders. MM138 and MM170 were the most radioresistant and MM96-L had intermediate sensitivity. In contrast, HT144 was markedly x-ray sensitive, despite retaining a shoulder and like the other lines, having a low (α(β)) ratio. There were no significant differences in DNA double strand break induction between the cell lines, and thus no correlation existed between DNA double strand break induction and radiosensitivity. Consistent with the shoulders on the x-ray survival curves, all four cell lines showed efficient DNA double strand break rejoining. Highly efficient DNA double strand break rejoining could account for the radioresistance of one of the melanoma lines (MM138). For example, MM138 had rejoined 50% of the induced DNA double strand breaks by 5.5 min compared to 13-17 min for the other three cell lines. The development of postirradiation apoptosis was effectively excluded as the cause of the marked radiosensitivity of the HT144 cell line. Conclusion: Other factors (such as lesion repair fidelity or differential lesion tolerance) underlie the differences in the intrinsic radiosensitivity between these melanoma cell lines

  10. The influence of interleukin-2, feeder cells, and timing of irradiation on the radiosensitivity of human T lymphocytes assessed by the colony-forming assay

    International Nuclear Information System (INIS)

    The radiosensitivity of human lymphocytes was investigated by the method of colony formation in the absence of interleukin-2 (IL2) and feeder cells, both of which enhance growth of T-cell colonies. The shape of the survival curve and the radiosensitivity was shown to depend upon the ability of lymphocytes to produce IL2: the survival curve for lymphocytes that were the most competent producers of IL2 is the closest to linearity; the lymphocytes that were poor producers show biphasic survival curves. The radiosensitivity of the lymphocytes from the first group is less than that of the latter, when the comparison is based on the first part of the biphasic survival curve. This is more easily seen when cultures are irradiated 24 h after stimulation by phytohemagglutinin (the time of the peak IL2 production) than when cultures are irradiated 2 h before stimulation. This study demonstrates that growth conditions influence the response of lymphocytes to irradiation and that optimal growth conditions result in a linear survival curve

  11. Selective in vivo radiosensitization by 5-fluorocytosine of human colorectal carcinoma cells transduced with the E. coli cytosine deaminase (CD) gene

    International Nuclear Information System (INIS)

    Purpose: The E. coli cytosine deaminase (CD) gene encodes an enzyme capable of converting the nontoxic prodrug 5-fluorocytosine (5-FC) to 5-fluorouracil (5-FU), a known radiosensitizer. Having previously shown that combined CD suicide gene therapy and radiation (RT) results in pronounced radiosensitization in vitro, we progressed to in vivo studies of combined therapy. Methods and Materials: WiDr human colon cancer cells were transduced in vitro with the CD gene and cells expressing CD were selected for use as xenografts in a nude mouse model. After administration of 5-FC, tumors received 10-30 Gy local field radiation (RT) and tumor growth delay was compared to control animals receiving either 5-FU, 5-FC, or RT alone. Results: Maximal growth delay was seen in mice treated with 5-FC for 6 consecutive days prior to RT. Combined treatment with 15 Gy radiation resulted in a dose-modifying factor (DMF) of 1.50, and a greater DMF was observed with higher doses of radiation. There was no appreciable toxicity using this new approach. In contrast, a similar treatment of combined 5-FU and radiation resulted in considerable toxicity and no appreciable radiosensitization. Conclusion: The present results show that combined suicide gene therapy and RT results in pronounced antitumor effect without any notable toxicity. This indicates that the CD gene may be useful in the development of novel treatment strategies combining radiation and gene therapy in the treatment of locally advanced cancers

  12. Involvement of placental/umbilical cord blood acid-base status and gas values on the radiosensitivity of human fetal/neonatal hematopoietic stem/progenitor cells

    International Nuclear Information System (INIS)

    Arterial cord blood (CB) acid-base status and gas values, such as pH, PCO2, PO2, HCO3- and base excess, provide useful information on the fetal and neonatal condition. However, it remains unknown whether these values affect the radiosensitivity of fetal/neonatal hematopoiesis. The present study evaluated the relationship between arterial CB acid-base status, gas values, and the radiosensitivity of CB hematopoietic stem/progenitor cells (HSPCs). A total of 25 CB units were collected. The arterial CB acid-base status and gas values were measured within 30 min of delivery. The CD34+ HSPCs obtained from CB were exposed to 2 Gy X-irradiation, and then assayed for colony-forming unit-granulocyte-macrophage, burst-forming unit-erythroid (BFU-E), and colony-forming unit-granulocyte erythroid, macrophage and megakaryocyte cells. Acid-base status and gas values for PCO2 and HCO3- showed a statistically significant negative correlation with the surviving fraction of BFU-E. In addition, a significant positive correlation was observed between gestational age and PCO2. Moreover, the surviving fraction of BFU-E showed a significant negative correlation with gestational age. Thus, HSPCs obtained from CB with high PCO2/HCO3- levels were sensitive to X-irradiation, which suggests that the status of arterial PCO2/HCO3- influences the radiosensitivity of fetal/neonatal hematopoiesis, especially erythropoiesis. (author)

  13. Influence of pEgr1-hsTRAIL plasmid on radiosensitivity and DR4 and DR5 expression levels in lung adencarcinoma A549 cells

    International Nuclear Information System (INIS)

    Objective: To measure the changes of the radiosensitivity in human lung adenocarcinoma A549 cells transfected with pEgr1-hsTRAIL plasmid and the effect on death receptor (DR) 4 and DR5 expressions, and to explore the radiosensitizing effect of pEgr1-hsTRAIL plasmid and possible mechanism on inducing apoptosis. Methods: There were normal control, pEgr1-hsTRAIL, 6 Gy X-rays, and pEgr1-hsTRAIL + 6 Gy X-rays groups in the experiment. After the A549 cells were transfected with liposome, and irradiated with X-rays, colony formation assay was used to measure the radiosensitivity, and reverse transcription PCR (RT-PCR) was performed to detect the DR4 and DR5 mRNA expressions, and Western blotting was applied to determine the DR4 and DR5 protein expressions. Results: The D0 values of A549 cells in normal control group and pEgr1-hsTRAIL group were 3.26 and 1.91 Gy, respectively, it indicated that pEgr1-hsTRAIL plasmid could enhance the radiosensitivity in A549 cells. The RT-PCR results showed that as compared with normal control group, the DR4 and DR5 mRNA expression levels in pEgr1-hsTRAIL group had no significant change, but those in 6 Gy X-rays group were increased significantly (P<0.05), and those in pEgr1-hsTRAIL + 6 Gy X-rays group were also increased significantly (P<0.05); the DR5 mRNA expression level in pEgr1-hsTRAIL + 6 Gy X-rays group was higher than that in 6 Gy X-rays group (P<0.05). The Western blotting results showed that the DR4 and DR5 protein expressions in pEgr1-hsTRAIL group did not change obviously compared with normal control group, but those in 6 Gy X-rays and pEgr1-hsTRAIL + 6 Gy X-rays groups were increased, and the DR5 protein expression in pEgr1-hsTRAIL + 6 Gy X-rays group was increased mostly. Conclusion: The recombinant plasmid pEgr1-hsTRAIL can enhance the radiosensitivity of A549 cells, and has the enhancing effect on DR5 expression induced by radiation, but no same effect on DR4 expression. (authors)

  14. Radiosensitization of epithelial growth factor receptor monoclonal antibody on lung adenocarcinoma cell line SPC-A-1

    International Nuclear Information System (INIS)

    Objective: To explore the radiosensitivity of C225 (cetuximab), an anti-epithelial growth factor receptor monoclonal antibody, which combined with irradiation against lung adenocarcinoma cell line SPC-A-1, and provide theoretical basis for clinical combined treatment in non-small lung cancer. Methods: SPC-A-1 were cultivated in vitro for 6 passages, and the SPC-A-1 in logarithmic growth phase were selected for experiment. The SPC-A-1 were divided into control group (PBS), irradiation group (4 Gy), C225 group (100 nmol ·L-1) and irradiation +C225 group (4 Gy + 100 nmol · L-1). The apoptosis of SPC-A-1 was observed by fluorescence microscope after Hoechst 33258 staining. SPC-A-1 were treated with different doses of 6-MV X-Rays including 0, 2, 4 and 8 Gy alone or together with C225 (100 nmol · L-1), 72 h after irradiation,the cells were divided into irradiation group and experimental group (irradiation + C22), the apototic rate was detected by flow cytometry (FCM). SPC-A-1 were divided into control group (PBS), C225 group (100 nmol · L-1), irradiation group (8 Gy) and irradiation + C225 group (8 Gy + 100 nmol · L-1), 48 h after irradiation, the cell cycle was determined by FCM. Results: After staining by Hoechst 33258, the number of apoptotic cells in irradiation + C225 group was significantly higher than those in irradiation group and C225 group. In apoptosis experiment, the apoptotic rate in experimental group was higher than that in irradiation group (P0+G1 phase was increased in C225 group (P0+G1 and G2+M phrases in irradiation +C225 group was increased (P0+G1 phases and inducing apoptosis. (authors)

  15. Radiosensitization by nickel lapachol

    International Nuclear Information System (INIS)

    The properties of interest in the radiosensitization of a metal complex, nickel lapachol, are compared with those of the 2-nitroimidazole, misonidazole. These very different compounds were found to be surprisingly similar in terms of their reduction potential (-370 mV), enhancement ratios for killing of hypoxic Chinese hamster ovary cells by X-irradiation, and enhancement of DNA breaks in hypoxia. For nitroimidazoles, the sensitization depends on 'electron affinity', reduction of the nitro group; for nickel lapachol it is the metal which is necessary for reduction, yet the sensitization efficiencies are remarkably close. However, the metal complex has additional activities (some sensitization in aerobic cells; increased sensitization with preincubation) which are as yet unexplained but are assumed to be related to the nature of the naphthoquinone ligand, rather than to the reduction of the metal. (Author)

  16. Pretreatment with rituximab enhances radiosensitivity of non-Hodgkin's lymphoma cells

    International Nuclear Information System (INIS)

    The present study examines the effects of ionizing radiation in combination with rituximab (RTX), a chimeric human anti-CD20 monoclonal antibody, on proliferation, cell cycle distribution and apoptosis in B-lymphoma RL and Raji cells. Exposure to ionizing radiation (9 Gy) induced cell growth delay and apoptosis in RL cells, whereas Raji cells showed moderate radio-resistance. The simultaneous exposure of lymphoma cells to ionizing radiation and RTX (10 μg/mL) markedly enhanced apoptosis and cell growth delay in RL and Raji cells. Cooperative antiproliferative and apoptotic effects of RTX and radiation were achieved through the inhibition of c-myc and bcl-XL expression. Furthermore, RTX-modulated expression of cell cycle regulating proteins, such as p53, p21/WAF1, p27/KIP1, contributed to the development of radiation-induced cell killing and growth arrest. Each NHL cell line that underwent apoptosis induced by combination treatment revealed enhanced caspase-3 and poly (ADP-ribose) polymerase (PARP) cleavage as compared to only irradiated cells. These findings show that rituximab synergistically enhances radiation-induced apoptosis and cell growth delay through the expression of proteins involved in the programmed cell death and cell cycle regulation pathways. (author)

  17. Cultures of cancer patient's skin tissue fibroblast and radiosensitivity assay

    International Nuclear Information System (INIS)

    In order to test the radiosensitivity of normal skin tissue, the authors cultured cancer patient's skin tissue fibroblast, surviving fraction experiment was employed to provide data for understanding of the different radiosensitivity among the cancer patients, Method: cancer patient's skin tissue fibroblast were cultured in vitro by the way of tar's attachment, cells were irradiated by graded doses of γ-ray , cell dose response experiment was used to test the radiosensitivity of cell. Result: Cancer patient's skin fibroblast could be propagated and passaged by the method of culture in vitro. Radiosensitivity are different among the various cancer patient's skin tissue fibroblasts

  18. Targeting Mcl-1 for Radiosensitization of Pancreatic Cancers

    Directory of Open Access Journals (Sweden)

    Dongping Wei

    2015-02-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-05-01

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

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

    International Nuclear Information System (INIS)

    Purpose: We compared radiosensitivity of brain tumor stem cells (BTSCs) with matched nonstem glioma cells, and determined whether gefitinib enhanced BTSC radiosensitivity by inhibiting epidermal growth factor receptor (EGFR)–Akt-DNA–dependent protein kinase (DNA-PK) signaling, followed by enhanced DNA double-stand breaks (DSBs) and inhibition of DSB repair. Methods and Materials: Radiosensitivity of stem-like gliomaspheres and nonstem glioma cells (obtained at patient neurosurgical resection) were evaluated by clonogenic assays, γ-H2AX immunostaining and cell cycle distribution. Survival of irradiated and nonirradiated NOD-SCID mice intracranially implanted with stem-like gliomaspheres were monitored. Glioma cells treated with gefitinib, irradiation, or both were assayed for clonogenic survival, γ-H2AX immunostaining, DNA-PKcs expression, and phosphorylation of EGFR and Akt. Results: Stem-like gliomaspheres displayed BTSC characteristics of self-renewal; differentiation into lineages of neurons, oligodendrocytes, and astrocytes; and initiation of glioma growth in NOD-SCID mice. Irradiation dose-dependently reduced clonogenic survival, induced G2/M arrest and increased γ-H2AX immunostaining of nonstem glioma cells, but not stem-like gliomaspheres. There was no difference in survival of irradiated and nonirradiated mice implanted with stem-like gliomaspheres. The addition of gefitinib significantly inhibited clonogenic survival, increased γ-H2AX immunostaining, and reduced DNA-PKcs expression of irradiated stem-like gliomaspheres, without affecting irradiated-nonstem glioma cells. Gefitinib alone, and when combined with irradiation, inhibited phosphorylation of EGFR (Y1068 and Y1045) and Akt (S473) in stem-like gliomaspheres. In nonstem glioma cells, gefitinib alone inhibited EGFR Y1068 phosphorylation, with further inhibition by combined gefitinib and irradiation. Conclusions: Stem-like gliomaspheres are resistant to irradiation-induced cytotoxicity, G2/M

  1. Early increase of radiation-induced γH2AX foci in a human Ku70/80 knockdown cell line characterized by an enhanced radiosensitivity

    International Nuclear Information System (INIS)

    A better understanding of the underlying mechanisms of DNA repair after exposure to ionizing radiation represents a research priority aimed at improving the outcome of clinical radiotherapy. Because of the close association with DNA double strand break (DSB) repair, phosphorylation of the histone H2AX protein (γH2AX), quantified by immunodetection, has recently been used as a method to study DSB induction and repair at low and clinically relevant radiation doses. However, the lack of consistency in literature points to the need to further validate the role of H2AX phosphorylation in DSB repair and the use of this technique to determine intrinsic radiosensitivity. In the present study we used human mammary epithelial MCF10A cells, characterized by a radiosensitive phenotype due to reduced levels of the Ku70 and Ku80 repair proteins, and investigated whether this repair-deficient cell line displays differences in the phosphorylation pattern of H2AX protein compared to repair-proficient MCF10A cells. This was established by measuring formation and disappearance of γH2AX foci after irradiating synchronized cell populations with 60Co γ-rays. Our results show statistically significant differences in the number of γH2AX foci between the repair-deficient and -proficient cell line, with a higher amount of γH2AX foci present at early times post-irradiation in the Ku-deficient cell line. However, the disappearance of those differences at later post-irradiation times questions the use of this assay to determine intrinsic radiosensitivity, especially in a clinical setting. (author)

  2. Membrane specific drugs as radiosensitizers

    Energy Technology Data Exchange (ETDEWEB)

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

    1981-01-01

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

  3. Use of halogenated thymidine analogs as clinical radiosensitizers: rationale, current status, and future prospects: non-hypoxic cell sensitizers

    International Nuclear Information System (INIS)

    The halogenated pyrimidine analogs, bromodeoxyuridine (BUdR) and iododeoxyuridine (IUdR) have been recognized as potential clinical radiosensitizers for over two decades. In vivo and in vitro experimental studies document that radiosensitization is directly dependent on the amount of thymidine replacement in DNA by these analogs. Based on recent in vivo and clinical pharmacology studies on continuous intravenous infusions of these drugs, clinical trials are underway evaluating the potential of radiosensitization in high grade gliomass and other poorly radioresponsive tumors using the technically safer intravenous route of administration. In this paper, the authors review the basic strategy for the use of these analogs, the ongoing clinical trials and the potential areas for future experimental and clinical studies

  4. The ribonucleoside diphosphate reductase inhibitor (E)-2'-Deoxy-(fluoromethylene) cytidine, acts as a cytotoxic radiosensitizer on human cancer cell lines in vitro.

    OpenAIRE

    Coucke, Philippe; Decosterd, L-A; Li, Y-X; Cottin, E.; Chen, X; Sun, L-Q; Stern, S.; Paschoud, N; Denekamp, J.

    1999-01-01

    ABSTRACT (E)-2*-Deoxy-(fluoromethylene)cytidine (FMdC) is known as an inhibitor of ribonucleoside diphosphate reductase, a key enzyme in the de novo pathway of DNA synthesis. FMdC was tested as a modifier of radiation response in vitro on a human colon carcinoma cell line (WiDr), and the observed radiosensitization was confirmed on two human cervix cancer cell lines (C33-A and SiHa). Using the clonogenic assay, the effect ratio (ER) at a clinically relevant dose level of ...

  5. Thermo-radiosensitivity of the granulocyte and macrophage precursor cells of mice. I I . - X- irradiation effects and influence of hyperthermia on the radiosensitivity; Termo-radiosensibilidad del precursor hematopoyetico que origina las series granulocitica y macrofaga de raton. II. - Efectos producidos por la radiacion X e influencia de la hipertermia sobre la radiosensibilidad celular

    Energy Technology Data Exchange (ETDEWEB)

    Bueren, J. A.; Nieto, M.

    1983-07-01

    The effects of the X-irradiation on the viability of the granulocyte-macrophage precursors, has been determined by means of the agar diffusion chamber culture technique. The results show the high radiosensitivity of these cells, with survival parameter similar to those previously reported in the literature about different granulocyte-macrophage precursors. When a hyperthermic treatment is performed prior to the X-irradiation, a radiosensitization phenomenon is observed due to the synergism existent between hyperthermia and X rays on the lethality of the precursors. (Authors) 37 refs.

  6. The radiosensitivity of a murine fibrosarcoma as measured by three cell survival assays.

    Science.gov (United States)

    Rice, L; Urano, M; Suit, H D

    1980-04-01

    The radiation sensitivity of a weakly immunogenic spontaneous fibrosarcoma of the C3Hf/Sed mouse (designated FSa-II) was assessed by three in vivo cell survival methods: end-point dilution (TD50) assay, lung colony (LC) assay, and agar diffusion chamber (ADC) assay. The hypoxic fraction of this tumour was also determined by the ADC method. Although there was a good agreement of the cell survival data between the ADC and LC methods, the TD50 method yielded a considerably less steep cell survival curve. Beneficial aspects and limitations of each assay are discussed. In addition, the use of the ADC method for the growth of xenogeneic cell lines and a preliminary experiment with human tumour cells in non-immunosuppressed hosts suggest that this method may be a valuable adjunct for studying the growth and therapeutic responses of human tumour cells. PMID:6932931

  7. Effect of Chronic Exposure to Acidic Environment on Radiosensitivity of Gliosarcoma Cells

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sora; Kim, Eunhee [Seoul National Univ., Seoul (Korea, Republic of)

    2014-05-15

    In this study, the chronic exposure of cells to acid culture medium, prior or posterior to irradiation, has been investigated for its effect on clonogenic cell survival. Unconventional high-dose radiation therapy, such as SRS, SBRT and MRT, may cause severe vascular damage in tumors, thereby a number of tumor cells facing chronic hypoxia and thus acidosis. According to our observation, gliosarcoma cells become more vulnerable to radiation damage by chronic exposure to acidic condition before irradiation. The longer the preirradiation exposure is, the more vulnerable to radiation damage the cells become. However, the repair of PLD by post-irradiation exposure to acid medium is efficient enough to eliminate the difference in number of the cells carrying PLDs due to different durations of preirradiation exposure to acidic condition.

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

    International Nuclear Information System (INIS)

    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)

  9. Studies of the effect on the cell cycle and of the radiosensitization of a novel anti-cancer agent TZT-1027

    International Nuclear Information System (INIS)

    The anticancer agent TZT-1027, an analog of dolastatin 10 originated from a marine organism, is an anti-microtubule agent and the present studies were performed to elucidate its activities in the title. Cell cycle analysis was done in mouse breast carcinoma tsFT210 cell line by flow-cytometry, which revealed that TZT-1027 specifically acted at G2/M, the stage most sensitive to radiation. Human non-small cell lung cancer H460 cell line was used for clonogenic assay: the dose enhancement factor at survival 0.1, estimated by the survival curve of cells irradiated by 60Co gamma ray at 0-6 Gy with or without TZT-1027, was found to be 1.2, which revealed the enhancement of radiosenstivity. In addition, their radiation-induced apoptosis was found to be also enhanced by the agent. When nude-mice transplanted with H460 cells were treated with TZT-1027 and 60Co gamma ray at 10 Gy, radiosensitization and apoptosis enhancement by the agent were also clear in vivo. Thus, TZT-1027 enhances the anti-tumor effect of radiation and this radiosensitizing mechanism involves the apoptotic process at least partly, both of which are conceivably the basis of future clinical trial of the agent. (T.I.)

  10. AT cells are not radiosensitive for simple chromosomal exchanges at low dose

    Energy Technology Data Exchange (ETDEWEB)

    Hada, Megumi; Huff, Janice L.; Patel, Zarana S. [USRA Division of Life Sciences, Houston, TX 77058 (United States); Kawata, Tetsuya [Department of Radiology, School of Medicine, Keio University, Tokyo (Japan); Pluth, Janice M. [Lawrence Berkeley National Laboratory, Life Sciences Division, One Cyclotron Road, Building 74, Berkeley, CA 94720 (United States); George, Kerry A. [Wyle, 1290 Hercules Drive, Houston, TX 77058 (United States); Cucinotta, Francis A., E-mail: Francis.A.Cucinotta@nasa.gov [NASA, Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, TX 77058 (United States)

    2011-11-01

    Cells deficient in ATM (product of the gene that is mutated in ataxia telangiectasia patients) or NBS (product of the gene mutated in the Nijmegen breakage syndrome) show increased yields of both simple and complex chromosomal aberrations after high doses (>0.5 Gy) of ionizing radiation (X-rays or {gamma}-rays), however less is known on how these cells respond at low dose. Previously we had shown that the increased chromosome aberrations in ATM and NBS defective lines was due to a significantly larger quadratic dose-response term compared to normal fibroblasts for both simple and complex exchanges. The linear dose-response term for simple exchanges was significantly higher in NBS cells compared to wild type cells, but not for AT cells. However, AT cells have a high background level of exchanges compared to wild type or NBS cells that confounds the understanding of low dose responses. To understand the sensitivity differences for high to low doses, chromosomal aberration analysis was first performed at low dose-rates (0.5 Gy/d), and results provided further evidence for the lack of sensitivity for exchanges in AT cells below doses of 1 Gy. Normal lung fibroblast cells treated with KU-55933, a specific ATM kinase inhibitor, showed increased numbers of exchanges at a dose of 1 Gy and higher, but were similar to wild type cells at 0.5 Gy or below. These results were confirmed using siRNA knockdown of ATM. The present study provides evidence that the increased radiation sensitivity of AT cells for chromosomal exchanges found at high dose does not occur at low dose.

  11. Experimental Study on the Radiosensitivity and Chemosensitivity of A-431 Cell Line

    International Nuclear Information System (INIS)

    The purpose of this study was to aid in the prediction of tumor cell tolerance to radiotherapy and/or chemotherapy. Human epidermoid carcinoma A-431 cell line were irradiated by 2, 4, 6, 8, 10 Gy at a dose rate of 210 cGy/min using 60Co Irradiator ALDORADO 8 and then were exposed to bleomycin or cisplatin at concentration of 2 μg/ml for 1 hour. The viable cells were determined for each radiation dose and/or each drug at the 4th day and cell surviving curves were obtained using semiautomated MTT assay. The surviving fraction after irradiation of 2 Gy was 0.99, and there was not significant difference of surviving fraction in comparison with the control group on A-431 cell line (p>0.05). But there were significant differences of surviving fractions at doses of 4, 6, 8, 10 Gy in comparison with the control group (p0.05).

  12. In vitro studies on radiosensitization effect of glucose capped gold nanoparticles in photon and ion irradiation of HeLa cells

    Science.gov (United States)

    Kaur, Harminder; Pujari, Geetanjali; Semwal, Manoj K.; Sarma, Asitikantha; Avasthi, Devesh Kumar

    2013-04-01

    Noble metal nanoparticles are of great interest due to their potential applications in diagnostics and therapeutics. In the present work, we synthesized glucose capped gold nanoparticle (Glu-AuNP) for internalization in the HeLa cell line (human cervix cancer cells). The capping of glucose on Au nanoparticle was confirmed by Raman spectroscopy. The Glu-AuNP did not show any toxicity to the HeLa cell. The γ-radiation and carbon ion irradiation of HeLa cell with and without Glu-AuNP were performed to evaluate radiosensitization effects. The study revealed a significant reduction in radiation dose for killing the HeLa cells with internalized Glu-AuNPs as compared to the HeLa cells without Glu-AuNP. The Glu-AuNP treatment resulted in enhancement of radiation effect as evident from increase in relative biological effectiveness (RBE) values for carbon ion irradiated HeLa cells.

  13. A Study on the radiosensitivity and chemosensitivity of YAC-1 Cell Line in Vitroand Maxillofacial

    International Nuclear Information System (INIS)

    The purpose of this study was to aid in the prediction of tumor cell tolerance to radiotherapy and/or chemotherapy. For this study, cell surviving curves were obtained for mouse lymphoma YAC-1 cell line using semiautomated MTT assay. 2, 4, 6, 8, 10 Gy were irradiated at a dose rate of 210 cGy/min using 60Co Irradiator ALDORADO 8. After irradiation, YAC-1 cell lines (3 X 104 cells/ml) were exposed to bleomycin or cisplatin for 1 hour. The viable cells were determined for each radiation dose and/or each concentration of drug at the 4th day. And they were compared to control values. The obtained results were as follows : 1. The surviving curve with gentle slope was obtained after irradiation of 2, 4, 6, 8, 10 Gy on YAC-1 cell line. 2. The cytotoxicity of bleomycin or cisplatin was increased significantly at all concentration of 0.2 μg/ml, 2 μg/ml and 20 μg/ml on YAC-1 cell line (P<0.01). 3. There were no significant differences of surviving fractions among 4 Gy, 6 Gy, and 8 Gy after irradiation of each radiation dose with 2 μg/ml of bleomycin compared with irradiation only on YAC-1 cell line (P<0.05). 5. There were significant differences of surviving fractions between the groups of irradiation only and the groups of irradiation with 2 μg/ml of bleomycin or cisplatin at all doses of 2, 4, 6, 8 and 10 Gy on YAC-1 cell line (P<0.05).

  14. An experimental study on the radiosensitivity and chemosensitivity of MG-63 cell line

    International Nuclear Information System (INIS)

    The purpose of this study was to aid in the prediction of tumor cell tolerance to radiotherapy and/or chemotherapy. For this study, cell surviving curves were obtained for human osteosarcoma MG-63 cell line using semiautomated MTT ass ay. 2, 4, 6, 8, 10 Gy were irradiated at a dose rate of 210 cGy/min using 60Co Irradiator ALDORADO 8. After irradiation, MG- 63 cell lines (3X104 cells/ml) were exposed to bleomycin and cisplatin at concentration of 0.2, 2, 20 μg/ml for 1 hour respectively. The viable cells were determined for each radiation dose and/or each concentration of drug. And they were compared to control values. The obtained results were as follows: 1. There was significant difference of surviving fraction at 4, 6, 8, 10 Gy on MG-63 cell line (p<0.05). 2. There was significant difference of cytotoxicity of bleomycin or cisplatin at all concentration of 0.2, 2, 20 μg/ml (p<0.05) on mg-63 cell line. The cytotoxicity of cisplatin was more effective than bleomycin at concentration after irradiation of 2 Gy on MG-63 cell line. 3. there was significant difference of cytotoxicity of bleomycin or cisplatin at all concentration after irradiation of Gy on MG-63 cell line. 4. There was significant difference of cytotoxicity of bloeomycin or cisplatin at concentration of 20 μg/ml after irradiation than that of irradiation alone (p<0.01). but there was no significant difference of cytotoxicity of bleomycin at concentration of 20 μg/ml after irradiation of 10 Gy than that of irradiation alone.

  15. Micronuclei versus Chromosomal Aberrations Induced by X-Ray in Radiosensitive Mammalian Cells.

    Directory of Open Access Journals (Sweden)

    Cristina Plamadeala

    2015-03-01

    Full Text Available An experimental study was accomplished to compare estimation methods of ionizing radiations genotoxicity in mammalian cell cultures by means of two cytogenetic parameters with focus on aberrant cells characterized by multiple chromosomal damages.In vitro study was carried out on the genotoxicity of low-medium doses of 190 kV X-rays absorbed in Chinese hamster ovary cell cultures. Micronuclei and ten types of chromosomal aberrations were identified with Giemsa dying and optical microscope screening.The first parameter consisting in micronuclei relative frequency has led to higher linear correlation coefficient than the second one consistent with chromosomal aberrations relative frequency. However, the latter parameter estimated as the sum of all chromosomal aberrations appeared to be more sensitive to radiation dose increasing in the studied dose range, from 0 to 3 Gy. The number of micronuclei occurring simultaneously in a single cell was not higher than 3, while the number of chromosomal aberrations observed in the same cell reached the value of 5 for doses over 1 Gy.Polynomial dose-response curves were evidenced for cells with Ni micronuclei (i=1,3 while non-monotonic curves were evidenced through detailed analysis of aberrant cells with Ni chromosomal changes [Formula: see text] - in concordance with in vitro studies from literature. The investigation could be important for public health issues where micronucleus screening is routinely applied but also for research purposes where various chromosomal aberrations could be of particular interest.

  16. Radiosensitization of renal cell carcinoma in vitro through the induction of autophagy

    International Nuclear Information System (INIS)

    Background and purpose: For patients diagnosed with advanced renal cell carcinoma (RCC), there are few therapeutic options. Radiation therapy is predominantly used to treat metastasis and has not proven effective in the adjuvant setting for renal cancer. Furthermore, RCC is resistant to standard cytotoxic chemotherapies. Targeted anti-angiogenics are the standard of care for RCC but are not curative. Newer agents, such as mTOR inhibitors and others that induce autophagy, have shown great promise for treating RCC. Here, we investigate the potential use of the small molecule STF-62247 to modulate radiation. Materials and methods: Using RCC cell lines, we evaluate sensitivity to radiation in addition to agents that induce autophagic cell death by clonogenic survival assays. Furthermore, these were also tested under physiological oxygen levels. Results: STF-62247 specifically induces autophagic cell death in cells that have lost VHL, an essential mutation in the development of RCC. Treatment with STF-62247 did not alter cell cycle progression but when combined with radiation increased cell killing under oxic and hypoxic/physiological conditions. Conclusions: This study highlights the possibility of combining targeted therapeutics such as STF-62247 or temsirolimus with radiation to reduce the reliance on partial or full nephrectomy and improve patient prognosis.

  17. Radiosensitivity of prostatic cell lines: bicalutamide effect (Casodex), micro-RNAs actions

    International Nuclear Information System (INIS)

    The first aim of our study was to evaluate the effect of the association between bicalutamide, an androgen receptor inhibitor, and ionizing radiation in three prostate cancer cell lines. The second aim was to examine a possible correlation between the expression of miR-210 or miR-373, the tolerance to hypoxia tolerance and the responses to radiation.We found that bicalutamide produced cytostatic and cytotoxic effects in the androgen receptor- positive LNCaP cell line. The androgen receptor-negative DU145 and PC3 cell lines were more resistant to bicalutamide. However, these cell lines were affected by high bicalutamide concentration with the same endpoints as for LNCaP cells. The inhibition of proliferation by bicalutamide was associated with G1 cell cycle phase arrest, increased expression of p27KIP1 protein, and decreased expression of HER2 protein. Last but not least, bicalutamide elicited a marked radioprotective effect in LNCaP cells when associated with concomitant irradiation. This result suggests that bicalutamide and radiotherapy should not be delivered in close temporal proximity, especially in case of hypo-fractionated radiotherapy protocols.Hypoxia is a well known radioresistance factor in tumors and is associated with a bad prognosis in prostate cancer. In this study, we found that hypoxia promotes the expression of HIF-1α, CA9, VEGF and miR-210 but not miR-373 in prostate cancer cell lines irrespective of their androgen receptor status.Our findings suggest that miR-210 expression is correlated with resistance to hypoxia and could be used as a prognostic marker in prostate cancer. Conversely, miR-210 inhibition did not impact the radiation susceptibility of PC3 prostate cancer cell line under hypoxia. (author)

  18. TP53 induced glycolysis and apoptosis regulator (TIGAR) knockdown results in radiosensitization of glioma cells

    International Nuclear Information System (INIS)

    Background and purpose: The TP53 induced glycolysis and apoptosis regulator (TIGAR) functions to lower fructose-2,6-bisphosphate (Fru-2,6-P2) levels in cells, consequently decreasing glycolysis and leading to the scavenging of reactive oxygen species (ROS), which correlate with a higher resistance to cell death. The decrease in intracellular ROS levels in response to TIGAR may also play a role in the ability of p53 to protect from the accumulation of genomic lesions. Given these good prospects of TIGAR for metabolic regulation and p53-response modulation, we analyzed the effects of TIGAR knockdown in U87MG and T98G glioblastoma-derived cell lines. Methods/results: After TIGAR-knockdown in glioblastoma cell lines, different metabolic parameters were assayed, showing an increase in Fru-2,6-P2, lactate and ROS levels, with a concomitant decrease in reduced glutathione (GSH) levels. In addition, cell growth was inhibited without evidence of apoptotic or autophagic cell death. In contrast, a clear senescent phenotype was observed. We also found that TIGAR protein levels were increased shortly after irradiation. In addition, avoiding radiotherapy-triggered TIGAR induction by gene silencing resulted in the loss of capacity of glioblastoma cells to form colonies in culture and the delay of DNA repair mechanisms, based in γ-H2AX foci, leading cells to undergo morphological changes compatible with a senescent phenotype. Thus, the results obtained raised the possibility to consider TIGAR as a therapeutic target to increase radiotherapy effects. Conclusion: TIGAR abrogation provides a novel adjunctive therapeutic strategy against glial tumors by increasing radiation-induced cell impairment, thus allowing the use of lower radiotherapeutic doses.

  19. Affect on the structures self-assembly as modification factor for the cultured cell radiosensitivity

    International Nuclear Information System (INIS)

    An assumption is confirmed that the directed effect on the processes of subcellular organelle assembly can be one of the approaches to the modification of radiation damage. It is shown that total cell death rate is conditioned by the effect of toxic compounds (preparations of colchicine, phalloidine and taxol), and by radiobiological effects. It seems that the status of microtubules and microfilaments as integral structures, their organization in 3D cell space, level of different posttranslational modifications of cytoscheleton proteins may be of s-quipicant importance for the realization of the programme of interphase and reproductive death of irradiated cells

  20. Selective assessment of in vitro radiosensitivity of tumour cells and fibroblasts from single tumour biopsies using immunocytochemical identification of colonies in the soft agar clonogenic assay

    International Nuclear Information System (INIS)

    The assumed selective growth of tumour cells has formed the basis for the use of the soft agar clonogenic assay to test in vitro radio- and chemosensitivity of tumours. However, recent studies have demonstrated that fibroblasts proliferate in soft agar in addition to tumour cells. The present study was initiated to quantify the contaminating growth of non-malignant cells in the modified form of the Courtenay-Mills soft agar assay, in order to establish a reliable assay for estimating tumour cell radiosensitivity in squamous cell carcinomas of the head and neck. DNA flow cytometry analysis confirmed that 'tumour fibroblasts' (fibroblasts obtained from tumour biopsies) grow in soft agar. In contrast, white blood cells did not form colonies. Different media were tested with soft agar, but a selective medium for tumour cells was not found. Therefore, a colony filter-technique combined with an immunocytochemical analysis was developed to quantify the number of tumour cell and fibroblast colonies. In 12 tumour biopsies, 2-33% of the colonies were Cytokeratin AE1-3 positive, whereas 83-100% of the colonies were 5B5 fibroblast antibody positive. The parameter normally reported, the overall SF2 (surviving cell fraction at 2 Gy) based on colonies in agar, was found to be statistically significantly correlated to the fibroblast SF2, but not to the tumour cell SF2. The overall SF2 was significantly different from the tumour cell SF2 in half of the tumours. Furthermore, the tumour cell SF2 was not correlated to fibroblast SF2. In consequence of our findings, correcting for fibroblast contamination is a necessity, when studying in vitro sensitivity of tumour cells. Combining the soft agar clonogenic assay with the new colony filter-technique and the immunocytochemical analysis appear to be useful for making this routine correction and for measuring the in vitro radiosensitivity of both tumour cells and fibroblasts from single tumour biopsies, which is of interest in future

  1. siRNA in silencing the expression of DNA-dependent protein kinase and its effect on radiosensitivity of lung adenocarcinoma cells

    International Nuclear Information System (INIS)

    Objective: To discuss the role of DNA-dependent protein kinase catalytic subunit (DNA-DPKCS) in human lung adenocarcinoma cell line (A549) by using small interfering RNA (siRNA) to specifically knockdown DNA-DPKCS expression and its effects on cell proliferation, cell cycle and radio-sensitivity. Methods: The DNA-DPKCS-siRNA expression vector was constructed and transfected into A549 cell line. The transformed clones were randomly selected and isolated. The cell cycle distribution and apoptosis were analyzed by flow cytometry analysis. Cell survival was detected by using clonogenic formation as-say. Results: With specific inhibition of DNA-DPKCS expression, stable transfected cell line 549pRNA-DNA-DPKCS was constructed by RNA interference technique. The 549pRNA-C and 549pSUPER cell lines were the control cell lines transfected with control and blank plasmids, respectively. Compared with A549 cells, the expression levels of DNA-DPKCS mRNA (0.110: 1. 000), protein (0. 870: 2.967) and activity of DNA-DPKCS (0.004: 0.266) in 549pRNA-DNA-DPKCS cells were significantly lower (F = 80.55 ,P 2(0.25:0.76), D0 (1.42:1.62) and Dq (0.06: 1. 00) showed significant difference between 549pRNA-DNA-DPKCS and A549 cells (F = 996.86, P 2 (10.7%: 11.0%) phases was significantly decreased (F = 4.83, P<0.05 and F=32.04, P <0.01, respectively). Conclusions: In A549 cells, inhibit of DNA-DPKCS gene expression can enhance the radiosensitivity and affect cell cycle distribution. (authors)

  2. Brusatol Enhances the Radiosensitivity of A549 Cells by Promoting ROS Production and Enhancing DNA Damage

    Directory of Open Access Journals (Sweden)

    Xiaohui Sun

    2016-06-01

    Full Text Available NF-E2-related factor 2 (Nrf2 has been identified as a master regulatory factor in the protection of cells from oxidative and electrophilic stress. However, overexpression of Nrf2 in lung cancer may cause chemoresistance, as well as radioresistance. In this study, we examined the relationship between radioresistance and Nrf2 protein levels in H1299, A549, and H460 cells, and finally chose the A549 cell line to continue with due to its strong radioresistance and high Nrf2 protein levels. We found that the Nrf2 inhibitor, brusatol, could prevent the increase and accumulation of Nrf2 after exposure to irradiation. Additionally, following treatment with 80 nM brusatol, A549 cells became sensitive to irradiation, suffering severe DNA damage. Combination treatment with brusatol and ionizing radiation (IR can distinctly increase the level of reactive oxygen species in A549 cells, causing a 1.8-fold increase compared with the control, and a 1.4-fold increase compared with IR alone. In fact, in the treatment with both brusatol and IR, lung cancer cell proliferation is halted, gradually leading to cell death. Because Nrf2 is closely linked to DNA damage repair, inhibiting the function of Nrf2, as in brusatol treatment, may increase the DNA damage caused by radiotherapy or chemotherapy, possibly enhancing the efficacy of chemotherapeutic drugs. Our study is the first to demonstrate brusatol’s ability to enhance the responsiveness of lung cancer cells to irradiation, and its potential application as a natural sensitizer in radiotherapy.

  3. Brusatol Enhances the Radiosensitivity of A549 Cells by Promoting ROS Production and Enhancing DNA Damage.

    Science.gov (United States)

    Sun, Xiaohui; Wang, Qin; Wang, Yan; Du, Liqing; Xu, Chang; Liu, Qiang

    2016-01-01

    NF-E2-related factor 2 (Nrf2) has been identified as a master regulatory factor in the protection of cells from oxidative and electrophilic stress. However, overexpression of Nrf2 in lung cancer may cause chemoresistance, as well as radioresistance. In this study, we examined the relationship between radioresistance and Nrf2 protein levels in H1299, A549, and H460 cells, and finally chose the A549 cell line to continue with due to its strong radioresistance and high Nrf2 protein levels. We found that the Nrf2 inhibitor, brusatol, could prevent the increase and accumulation of Nrf2 after exposure to irradiation. Additionally, following treatment with 80 nM brusatol, A549 cells became sensitive to irradiation, suffering severe DNA damage. Combination treatment with brusatol and ionizing radiation (IR) can distinctly increase the level of reactive oxygen species in A549 cells, causing a 1.8-fold increase compared with the control, and a 1.4-fold increase compared with IR alone. In fact, in the treatment with both brusatol and IR, lung cancer