Analysis of the factors in determining radiosensitivity in mammalian cells by using radio-sensitive and -resistant clones isolated from HeLa S3 cells in vitro

International Nuclear Information System (INIS)

Nikaido, Osamu; Horikawa, Masakatsu

1976-01-01

The factors in determining radiosensitivity of cultured mammalian cells were analysed by using two clones each having different radiosensitivities. The radiosensitive clones were isolated from HeLa S3 cells by the N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-treatment, X-irradiation (200 R) and 5-bromodeoxyuridine (BUdR)-visible light method. On the other hand, the radioresistant clone was isolated by single X-irradiation (2000 R) from MNNG-treated HeLa S3 cell population. The radiosensitivities expressed in D sub(o) and D sub(q) values were 110 and 140 R in radiosensitive SM-1a clone and 180 and 230 R in radioresistant RM-1b clone respectively. The biological and biochemical characteristics of both clones such as the distribution of chromosome numbers, formation and rejoining of single strand breaks in DNA caused by X-irradiation, non-protein sulfhydryl (NPSH) and apparent total sulfhydryl (APSH) contents were measured. Among the characteristics analysed, different contents of NPSH in the cell were well correlated to their daiosensitivities among the original HeLa S3 cells, SM-1a and RM-1b clone. Additionally, it was found that the radioresistant L.P3 Co-3 cells isolated by Tsuboi et al. from the original mouse L.P3 cells by means of serial irradiation with 60 Co γ-rays have more abundant NPSH than the original L.P3 cells. From these results, it can be concluded that the amount of NPSH play the main role in determining radiosensitivity in cultured mammalian cells. (auth.)

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

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Debin Ma

2015-09-01

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

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

NARCIS (Netherlands)

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

2010-01-01

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

Radiosensitization of hypoxic tumor cells in vitro by nitric oxide

International Nuclear Information System (INIS)

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

1996-01-01

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

Radiosensitization of mouse spermatogenic stem cells by Ro-07-0582

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Suzuki, N.; Withers, R.; Hunter, N.

1977-01-01

The hypoxic character of the spermatogenic stem cells of the mouse testis was investigated by measuring the effect on radiosensitivity of treatment with the hypoxic cell radiosensitizer, Ro-07-0582 or hyperbaric oxygen (30 psi). The D 0 values obtained were 181 (161-207) rad for irradiation alone, 140 (133-148) rad for irradiation after treatment with Ro-07-0582, and about 100 rad for irradiation in the presence of hyperbaric oxygen. Ro-07-0582 alone was slightly cytotoxic. The results demonstrate that mouse spermatogenic stem cells are radiosensitized by Ro-07-0582 or hyperbaric oxygen and are not as well oxygenated as other normal tissues

Radiosensitizing efficiency of sodium glycididazole on V79 cells in vitro

International Nuclear Information System (INIS)

Zheng Xiulong; Gao Jianguo; Zhang Hong; Zhu Qin; Meng Xiangshun; Zhao Fang

1995-01-01

Radiosensitizing effect of sodium glycididazole (SGDD) on the hypoxic V 79 cells by standard in vitro colon formation method has been further studied. The results showed its toxicity was low. Its ID 50 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 (p 1.6 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

Effect of Quercetin on radio-sensitivity of HeLa cells

International Nuclear Information System (INIS)

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

2011-01-01

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

Prenyltransferase inhibitor radiosensitization of pancreatic ductal carcinoma (PaCa) cells

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

2003-01-01

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

Differential radiosensitivity among B cell subpopulations

International Nuclear Information System (INIS)

Riggs, J.E.

1988-01-01

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

Radiosensitization of hypoxic tumor cells by simultaneous administration of hyperthermia and nitroimidazoles

International Nuclear Information System (INIS)

Hofer, K.G.; Hofer, M.G.; Ieracitano, J.; McLaughlin, W.H.

1977-01-01

The radiation response of oxygenated and hypoxic L1210 leukemia cells subjected to in vivo treatments with hyperthermia and/or chemical radiosensitizers was evaluated with the [ 125 I]iododeoxyuridine prelabeling assay. X irradiation of L1210 cells at body temperatures of 41 0 C or higher resulted in strongly enhanced tumor cell death. The magnitude of this thermal effect increased with increasing temperatures. Hypoxic L1210 cells were particularly sensitive to heat induced enhancement of radiation damage, i.e., the sensitizing effects were more pronounced and occurred at lower temperatures. Chemical radiosensitizers (metronidazole, Ro 7-0582) selectively sensitized hypoxic L1210 populations; fully oxygenated cells were not affected. Considerable radiosensitization was achieved at nontoxic dose levels of the two sensitizers. Experiments designed to determine the degree of radiosensititization as a function of drug dose showed that Ro 7-0582 was consistently more effective than metronidazole in sensitizing hypoxic tumor populations. At the highest drug dose used (3 mg/g body wt) the DMF was 2.2 for metronidazole and 2.8 for Ro 7-0582. Combined administration of hyperthermia and Ro 7-0582 (or metronidazole) produced synergistic potentiation of radiation damage in hypoxic L1210 populations (DMF of 4.2). Under optimal conditions, hypoxic L1210 cells subjected simultaneously to both modes of radiosensitization became more radiosensitive than untreated, fully oxygenated L1210 cells. Experiments on two other tumor lines (BP-8 murine sarcoma and Ehrlich ascites cells) indicate that such synergistic radiosensitization effects are not unique to L1210 cells

Osmotic homeostasis and NKLy lymphoma cells radiosensitivity

International Nuclear Information System (INIS)

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

1992-01-01

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

Preferential radiosensitization of human prostatic carcinoma cells by mild hyperthermia

International Nuclear Information System (INIS)

Ryu, Samuel; Brown, Stephen L.; Kim, Sang-Hie; Khil, Mark S.; Kim, Jae Ho

1996-01-01

Purpose: Recent cell culture studies by us and others suggest that some human carcinoma cells are more sensitive to heat than are rodent cells following mild hyperthermia. In studying the cellular mechanism of enhanced thermosensitivity of human tumor cells to hyperthermia, prostatic carcinoma cells of human origin were found to be more sensitive to mild hyperthermia than other human cancer cells. The present study was designed to determine the magnitude of radiosensitization of human prostatic carcinoma cells by mild hyperthermia and to examine whether the thermal radiosensitization is related to the intrinsic thermosensitivity of cancer cells. Methods and Materials: Two human prostatic carcinoma cell lines (DU-145 and PC-3) and other carcinoma cells of human origin, in particular, colon (HT-29), breast (MCF-7), lung (A-549), and brain (U-251) were exposed to temperatures of 40-41 deg. C. Single acute dose rate radiation and fractionated radiation were combined with mild hyperthermia to determine thermal radiosensitization. The end point of the study was the colony-forming ability of single-plated cells. Results: DU-145 and PC-3 cells were found to be exceedingly thermosensitive to 41 deg. C for 24 h, relative to other cancer cell lines. Ninety percent of the prostatic cancer cells were killed by a 24 h heat exposure. Prostatic carcinoma cells exposed to a short duration of heating at 41 deg. C for 2 h resulted in a substantial enhancement of radiation-induced cytotoxicity. The thermal enhancement ratios (TERs) of single acute dose radiation following heat treatment 41 deg. C for 2 h were 2.0 in DU-145 cells and 1.4 in PC-3 cells. The TERs of fractionated irradiation combined with continuous heating at 40 deg. C were similarly in the range of 2.1 to 1.4 in prostate carcinoma cells. No significant radiosensitization was observed in MCF-7 and HT-29 cells under the same conditions. Conclusion: The present data suggest that a significant radiosensitization of

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

International Nuclear Information System (INIS)

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

2013-01-01

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

Preferential radiosensitization of G1 checkpoint--deficient cells by methylxanthines

International Nuclear Information System (INIS)

Russell, Kenneth J.; Wiens, Linda W.; Demers, G. William; Galloway, Denise A.; Le, Tiep; Rice, Glenn C.; Bianco, James A.; Singer, Jack W.; Groudine, Mark

1996-01-01

Purpose: To develop a checkpoint-based strategy for preferential radiosensitization of human tumors with deficient and/or mutant p53. Methods and Materials: A549 human lung adenocarcinoma cell lines differing in their expression of the p53 tumor suppressor gene were produced by transduction with the E6 oncogene from human papilloma virus type 16. The cells expressing E6 (E6+) lack a G1 arrest in response to ionizing radiation, are deficient in p53 and p21 expression, and exhibit a fivefold greater clonogenic survival following 10 Gy radiation. Results: Postirradiation incubation with millimolar concentrations of the methylxanthine pentoxifylline (PTX) results in preferential radiosensitization of the E6+ cells compared to the LXSN+ vector transduced controls. There is a threefold sensitization of the LXSN+ cells and a 15-fold sensitization of the E6+ cells, which results in equal clonogenic survival of the two lines. Flow cytometry reveals PTX abrogation of the radiation induced G2 arrest for both cell lines. PTX also prolongs G1 transit for both cell lines. Preliminary results are presented using a novel methylxanthine, lisofylline (LSF), which has similar cell cycle effects on G1 and G2 and achieves differential radiosensitization at micromolar concentrations that are sustainable in humans. Conclusions: This checkpoint-based strategy is a promising approach for achieving preferential radiosensitization of p53- tumors relative to p53+ normal tissues

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

International Nuclear Information System (INIS)

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

1993-01-01

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

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

International Nuclear Information System (INIS)

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

2010-01-01

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

Clonal cell populations unresponsive to radiosensitization induced by telomerase inhibition

International Nuclear Information System (INIS)

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

2010-01-01

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

Differences in radiosensitivity between three HER2 overexpressing cell lines

International Nuclear Information System (INIS)

Steffen, Ann-Charlott; Tolmachev, Vladimir; Stenerloew, Bo; Goestring, Lovisa; Palm, Stig; Carlsson, Joergen

2008-01-01

HER2 is a potential target for radionuclide therapy, especially when HER2 overexpressing breast cancer cells are resistant to Herceptin registered treatment. Therefore, it is of interest to analyse whether HER2 overexpressing tumour cells have different inherent radiosensitivity. The radiosensitivity of three often used HER2 overexpressing cell lines, SKOV-3, SKBR-3 and BT-474, was analysed. The cells were exposed to conventional photon irradiation, low linear energy transfer (LET), to characterise their inherent radiosensitivity. The analysis was made with clonogenic survival and growth extrapolation assays. The cells were also exposed to alpha particles, high LET, from 211 At decays using the HER2-binding affibody molecule 211 At-(Z HER2:4 ) 2 as targeting agent. Assays for studies of internalisation of the affibody molecule were applied. SKOV-3 cells were most radioresistant, SKBR-3 cells were intermediate and BT-474 cells were most sensitive as measured with the clonogenic and growth extrapolation assays after photon irradiation. The HER2 dependent cellular uptake of 211 At was qualitatively similar for all three cell lines. However, the sensitivity to the alpha particles from 211 At differed; SKOV-3 was most resistant, SKBR-3 intermediate and BT-474 most sensitive. These differences were unexpected because it is assumed that all types of cells should have similar sensitivity to high-LET radiation. The sensitivity to alpha particle exposure correlated with internalisation of the affibody molecule and with size of the cell nucleus. There can be differences in radiosensitivity, which, if they also exist between patient breast cancer cells, are important to consider for both conventional radiotherapy and for HER2-targeted radionuclide therapy. (orig.)

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

International Nuclear Information System (INIS)

Wilson, W.R.; Anderson, R.F.

1989-01-01

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

Effect of cisplatin on the clinically relevant radiosensitivity of human cervical carcinoma cell lines

International Nuclear Information System (INIS)

Britten, Richard A.; Evans, Andrew J.; Allalunis-Turner, M. Joan; Pearcey, Robert G.

1996-01-01

Purpose: To evaluate the effect of clinically relevant levels of cisplatin on the radiosensitivity of human cervical tumor cells, and to estimate what changes in local control rates might be expected to accrue from the concomitant use of cisplatin during fractionated radiotherapy. Methods and Materials: The effects of concomitant cisplatin (1 μg/ml, a typical intratumor concentration) on the clinically relevant radiosensitivity, i.e., surviving fraction after 2 G (SF 2 ) values, was determined in 19 cloned human cervical tumor cell lines. These early passage cell lines had SF 2 values ranging from 0.26 to 0.87. Results: The concomitant administration of cisplatin reduced the clinically relevant radiosensitivity in the majority (11 out of 19) of the human tumor cell lines investigated. In only 4 out of 19 was any radiosensitization observed, and in 4 out of 19 cell lines there was no significant change in radiosensitivity. However, the sum of the independent cell killing by radiation and cisplatin, was approximately twofold higher than after radiation alone. There was no apparent dependence of the cisplatin-induced changes in SF 2 values upon the level of cell killing by cisplatin. However, there is a suggestion that concomitant cisplatin administration may have a differential effect in inherently radiosensitive and resistant human tumor cell lines. Conclusions: Our data suggest that concomitant cisplatin/radiotherapy regimens may result in a higher level of local tumor control, but primarily through additive toxicity and not through radiosensitization. Future improvements in local tumor control may, thus, be derived by increasing the total dose of cisplatin

Radiosensitization of non-small cell lung cancer by kaempferol.

Science.gov (United States)

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

2015-11-01

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

Profound radiosensitivity in leukemic T-cell lines and T-cell-type acute lymphoblastic leukemia demonstrated by sodium [51Cr]chromate labeling

International Nuclear Information System (INIS)

Nakazawa, S.; Minowada, J.; Tsubota, T.; Sinks, L.F.

1978-01-01

Radiation sensitivity was determined by measuring spontaneous release from 51 Cr-labeled cells in various lymphoid cell populations. Among six leukemia T-cell lines originating from acute lymphoblastic leukemia, four such lines were found to be highly radiosensitive. In contrast, two of the leukemic T-cell lines and four normal control B-cell lines were not radiosensitive. Thymocytes from six patients and leukemia T-cell blasts from three patients with T-cell leukemia were likewise found to be highly radiosensitive, whereas leukemic blasts from six patients with null-cell (non-T, non-B-cell) acute lymphoblastic leukemia were not radiosensitive. Normal peripheral blood lymphocytes and mitogen-induced normal lymphoblasts were found not to be radiosensitive. The results indicate that measurement of the radiation sensitivity of acute leukemic blasts may have a therapeutic significance in coping with the heterogeneous nature of individual leukemia cases

Radiosensitization of nitroindazole derivatives on HeLa cells

International Nuclear Information System (INIS)

Wang Hao; Shi Peiji; Zhou Xiaoliang; Wang Yan; Tang Weisheng

2010-01-01

Objective: To investigate the cytotoxicity and radiosensitization of 5-nitroindazole-3-formyliminodiacetic acid on HeLa cells. Methods: HeLa cells in exponential growth phase were incubated in culture media with different doses and the survival rate was determined by MTT assay. The survival rate of cells receiving radiation combined with different doses of medicine was compared with that of the control.Results: The cytotoxicity of S-nitroindazole-3-formyliminodiacetic acid on HeLa cells was very low. The drug had hypoxia radiosensitizing effect on HeLa cells. At doses of 0, 6, 12, 24, 48 and 96 μg/ml under hypoxia, the survival rate were 0.91 , 0.87, 0.84, 0.81, 0.76 and 0.60, respectively. At the dosage of 48 and 96 μg/ml, the survival rate were 0.85 and 0.73 under oxygenous). Conclusions: 5-Nitroindazole-3-formyliminodiacetic acid has low cytotoxicity and rediosensitizing effect on HeLa cells. (authors)

Radiosensitization effect of CMNa on hypoxic pancreatic cancer cell in vitro

International Nuclear Information System (INIS)

Yin Lijie; Zhang Li; Ding Tiangui; Peng Zhaoxiang; Yu Huan; Gao Yuwei

2006-01-01

Objective: To investigate the effects of glycodidazolum natrium (CMNa) on pancreatic cancer cells under hypoxic condition. Methods: The human pancreatic cancer Panc-1 cells were exposed to a single fraction of high-dose γ-ray radiation either with CMNa or under hypoxic condition. The percentage of dead cells was detected with a multiwell plated reader, and fluorescence intensities of propidium iodide were measured before and after digitonin treatment. The sensitizing effect of CMNa on cell killing induced by high-dose irradiation was evaluated by time and concentration dependence. The selective radiosensitive effect of CMNa on hypoxia was evaluated by flow cytometry. Results: The death rate of pancreatic cancer Panc-1 cells paralleled with the increasing concentration of CMNa under hypoxic condition after 30 gray irradiation. The selective radiosensitive effect of CMNa on hypoxia was time-dependent. Conclusions: CMNa can enhance the radiosensitivity of pancreatic cancer Pane-1 cells under hypoxic condition with high-dose irradiation. (authors)

Overview of Radiosensitivity of Human Tumor Cells to Low-Dose-Rate Irradiation

International Nuclear Information System (INIS)

Williams, Jerry R.; Zhang Yonggang; Zhou Haoming; Gridley, Daila S.; Koch, Cameron J.; Slater, James M.; Little, John B.

2008-01-01

Purpose: We compared clonogenic survival in 27 human tumor cell lines that vary in genotype after low-dose-rate (LDR) or high-dose rate (HDR) irradiation. We measured susceptibility to LDR-induced redistribution in the cell cycle in eight of these cell lines. Methods and Materials: We measured clonogenic survival after up to 96 hours of LDR (0.25 Gy/h) irradiation. We compared these with clonogenic survival after HDR irradiation (50 Gy/h). Using flow cytometry, we measured LDR-induced redistribution as a function of time during LDR irradiation in eight of these cell lines. Results: Coefficients that describe clonogenic survival after both LDR and HDR irradiation segregate into four radiosensitivity groups that associate with cell genotype: mutant (mut)ATM, wild-type TP53, mutTP53, and an unidentified gene in radioresistant glioma cells. The LDR and HDR radiosensitivity correlates at lower doses (∼2 Gy HDR, ∼6 Gy LDR), but not at higher doses (HDR > 4 Gy; LDR > 6 Gy). The rate of LDR-induced loss of clonogenic survival changes at approximately 24 hours; wild-type TP53 cells become more resistant and mutTP53 cells become more sensitive. Redistribution induced by LDR irradiation also changes at approximately 24 hours. Conclusions: Radiosensitivity of human tumor cells to both LDR and HDR irradiation is genotype dependent. Analysis of coefficients that describe cellular radiosensitivity segregates 27 cell lines into four statistically distinct groups, each associating with specific genotypes. Changes in cellular radiosensitivity and redistribution in the cell cycle are strongly time dependent. Our data establish a genotype-dependent time-dependent model that predicts clonogenic survival, explains the inverse dose-rate effect, and suggests possible clinical applications

Gemcitabine radiosensitizes multiple myeloma cells to low let, but not high let, irradiation

International Nuclear Information System (INIS)

Supiot, Stephane; Thillays, Francois; Rio, Emmanuel; Gouard, Sebastien; Morgenstern, Alfred; Bruchertseifer, Frank; Mahe, Marc-Andre; Chatal, Jean-Francois; Davodeau, Francois; Cherel, Michel

2007-01-01

The radiosensitizing properties of gemcitabine in relation to low Linear Energy Transfer (LET) particles (Cobalt 60) and high-LET particles (alpha-RIT 213 Bi-radiolabeled CHX-DTPA-B-B4) were analyzed. Three multiple myeloma cell lines (LP1, RPMI 8226, U266) were irradiated with or without 10 nM gemcitabine 24 h prior to radiation. Gemcitabine led to radiosensitization of LP1 and U266 cells with low-LET (Radiation Enhancement Ratio: 1.55 and 1.49, respectively) but did not radiosensitize any cell line when combined with high-LET

Phytochemicals radiosensitize cancer cells by inhibiting DNA repair

International Nuclear Information System (INIS)

Singh, Rana P.

2017-01-01

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

Study of radiosensitization of chloroquine on esophageal cancer cell line

International Nuclear Information System (INIS)

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

2014-01-01

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

Radiosensitization of human endothelial cells by IL-24

International Nuclear Information System (INIS)

Meyn, R.E.

2003-01-01

Radiation therapy remains an important cancer treatment modality but despite improvements in dose delivery many patients still fail at their primary tumor site. Therefore, new strategies designed to improve local control are needed. Protocols combining radiation with anti-angiogenic agents might be of particular advantage based on their documented low toxicity. In this regard, we have been conducting preclinical investigations of a novel cytokine, mda7/IL-24. Our collaborators have shown that mda7/IL-24 protein targets the endothelial cells of the tumor microvascular system and has potent anti-angiogenic properties in both in vitro and in vivo assays. Recently, we have demonstrated that recombinant mda7/IL-24 protein radiosensitizes human endothelial cells in vitro. Specifically, 10 ng/ml of recombinant human IL-24 protein for 12 hrs reduced the survival at 2 Gy for human umbilical vein endothelial cells (HUVECs) from 0.33 to 0.12. We are also working on understanding the molecular basis for this radiosensitizing effect. Preliminary data suggest a model whereby mda7/IL-24 engages a specific receptor on the surface of endothelial cells and initiates a signal transduction pathway that modulates the cell's propensity for radiation-induced apoptosis and capacity for repairing radiation-induced DNA double strand breaks. Mechanistic insight gained from these studies may have implications for the actions of other anti-angiogenic agents and may generally explain the regulation of radiosensitivity imparted by growth factors and cytokines

LET effects on normal and radiosensitive cell lines

International Nuclear Information System (INIS)

Geard, C.R.; Travisano, M.

1986-01-01

Charged particles in the track segment mode were produced by the RARAF Van de Graaff accelerator and used to irradiate two CHO cell lines, a radiosensitive hypermutable line EM9 and its normal parent AA8. Asynchronous cells were irradiated attached to 6 micrometer thick Mylar with protons, deuterons and helium-3 particles at LETs ranging from 10 to 150 keV per micrometer. A 50 kVp x-ray tube integrated into the track segment facility provided a low LET comparison. Following irradiation cells were monitored for clonogenicity, and in a separate series of experiments frequencies of sister chromatid exchanges. Up to 9 experiments were carried out at each LET, with a total of 8 radiations of different LETs being compared. The optimally effective LET for cell survival was between 80 and 120 keV per micrometer, with the 150 keV per micrometer particles indicating energy wastage. The differential between the normal and radiosensitive cell lines was maintained at all LETs

The dependence of fibroblast radiosensitivity on cell pH

International Nuclear Information System (INIS)

Veksler, A.M.; Kublik, L.N.; Degtyareva, O.V.; Ehjdus, L.Kh.

1983-01-01

The problem of the change of radiosensitivity of Chinese hamster fibroblasts, irradiated under aerobic and hypoxic conditions in the course of intracellular pH (pHsub(intr.)) change by means of a phosphate buffer has been studied. It has been found that pHsub(intr.) reduction considerably increases the radiosensitivity, the effect being more pronounced on hypoxic cells which is essential for radiotherapy of tumors. The survival rate of cell irradiated under hypoxia conditions does not depend on season while cell resistance in case of irradiation in open air in spring and autumn is different. The effect discovery in case of pHsub(intr.) reduction upon irradiation shows up the influence of the studied factor on repair processes

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

International Nuclear Information System (INIS)

Shah, Tushar; Ryu, Samuel; Lee, Ho Jun; Brown, Stephen; Kim, Jae Ho

2002-01-01

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

Radiosensitization by PARP inhibition to proton beam irradiation in cancer cells

Energy Technology Data Exchange (ETDEWEB)

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

2016-09-09

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

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

Science.gov (United States)

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

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, and significantly enhanced the radiation-induced growth delay of FSaII tumors (s.c.) in the legs of C3H mice. Both metformin and ionizing radiation activated AMPK leading to inactivation of mTOR and suppression of its downstream effectors such as S6K1 and 4EBP1, a crucial signaling pathway for proliferation and survival of cancer cells, in vitro as well as in the in vivo tumors. Conclusion: Metformin kills and radiosensitizes cancer cells and eradicates radioresistant cancer stem cells by activating AMPK and suppressing mTOR. PMID:22500211

Heterogeneity of the radiosensitivity and origins of tissue macrophage colony-forming cells

Energy Technology Data Exchange (ETDEWEB)

Oghiso, Yoichi; Yamada, Yutaka (National Inst. of Radiological Sciences, Chiba (Japan))

1992-12-01

Previous studies suggest that the radiosensitivity and origin of tissue macrophage precursors differ from those of hemopoietic macrophage colony-forming units (CFU-Ms) committed to macrophage-lineage cells. We assessed the origins of tissue macrophage colony-forming cells (M-CFCs) in mice by comparing their kinetics and radiosensitivities in the normal steady state and under the conditions of bone marrow depletion by [sup 89]Sr-administration and/or splenectomy. The results indicate that the radiosensitive peritoneal M-CFCs elicited by thioglycollate are derived from bone marrow macrophage precursors; where as alveolar M-CFCs, which are radioresistant, are self-sustained locally and independent of hemopoietic macrophage precursors. In contrast, highly radiosensitive liver M-CFCs are probably derived from CFU-Ms that appear to be propagated in the spleen in association with hemopoietic responses. (author).

Chromatin structure and cellular radiosensitivity : A comparison of two human tumour cell lines

NARCIS (Netherlands)

Woudstra, EC; Roesink, JM; Rosemann, M; Brunsting, JF; Driessen, C; Orta, T; Konings, AWT; Peacock, JH; Kampinga, HH

1996-01-01

The role of variation in susceptibility to DNA damage induction was studied as a determinant for cellular radiosensitivity. Comparison of the radiosensitive HX142 and radioresistant RT112 cell lines previously revealed higher susceptibility to X-ray-induced DNA damage in the sensitive cell line

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

International Nuclear Information System (INIS)

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

2014-01-01

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

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

Science.gov (United States)

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

2015-01-01

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

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.

Radiosensitive xrs-5 and parental CHO cells show identical DNA neutral filter elution dose-response: implications for a relationship between cell radiosensitivity and induction of DNA double-strand breaks

International Nuclear Information System (INIS)

Iliakis, George; Okayasu, Ryuichi; Seaner, Robert

1988-01-01

The purpose of this work was to investigate a possible correlation between DNA elution dose-response and cell radiosensitivity. For this purpose neutral (pH 9.6) DNA filter elution dose-response curves were measured with radiosensitive xrs-5 and the parental Chinese hamster ovary (CHO) cells in the logarithmic and plateau phase of growth. No difference was observed between the two cell types in the DNA elution dose-response curves either in logarithmic or plateau phase, despite the dramatic differences in cell radiosensitivity. This observation indicates that the shape of the DNA elution dose-response curve and the shape of the cell survival curve are not causally related. It is proposed that the shoulder observed in the DNA elution dose-response curve reflects either partial release of DNA from chromatin, or cell cycle-specific alterations in the physicochemical properties of the DNA. (author)

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.

Relationship between α/β and radiosensitivity and biologic effect of fractional irradiation of tumor cells

International Nuclear Information System (INIS)

Guo Chuanling; Chinese Academy of Sciences, Beijing; Wang Jufang; Jin Xiaodong; Li Wenjian

2006-01-01

Five kinds of malignant human tumor cells, i.e. SMMC-7721, HeLa, A549, HT29 and PC3 cell lines, were irradiated by 60 Co γ-rays to 1-6 Gy in a single irradiation or two irradiations of half dose. The radiosensitivity was compared with the dose-survival curves and D 50 and D 10 values. Differences in the D 50 and D 10 between the single and fractional irradiation groups showed the effect of fractional irradiation. Except for PC3 cells, all the cell lines showed obvious relationship between radiosensitivity and biologic effect of fractional irradiation and the α/β value. A cell line with bigger α/β was more radiation sensitive, with less obvious effect of fractional irradiation. The results indicate that there were obvious differences in radiosensitivity, repair ability and biologic effect of fractional irradiation between tumor cells from different tissues. To some tumor cell lines, the relationship between radiosensitivity, biologic effect of fractional irradiation and repair ability was attested. The α/β value of single irradiation can be regarded as a parameter to investigate the radiosensitivity and biologic effect of fractional irradiation of tumor cells. (authors)

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)

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

1986-01-01

Three different cell lines, Ehrlich ascites tumour (EAT) cells, HeLa S 3 cells and LM mouse fibroblasts, were used to investigate whether or not the extent of heat killing (44 0 C) and heat radio-sensitization (44 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 0 , EAT = 8.0 min; D 0 , LM = 10.0 min; D 0 , 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)

Study on relationship between apoptosis-related genes and radiosensitivity of esophageal squamous cell carcinoma

International Nuclear Information System (INIS)

Li Huixiang; Wang Yaohe; Shi Yonggang; Gao Dongling; Zhang Yunhan

2000-01-01

Objective: To observing the relationship between apoptosis-related genes bcl-2,c-myc, p53 and the radiosensitivity of esophageal squamous cell carcinoma. Methods: The expression levels of bcl-2, c-myc and p53 genes in 57 biopsy samples from patients of esophageal squamous cell carcinoma were detected with the LSAB immunohistochemistry method. All the patients were treated with radiotherapy. The radiotherapeutic effect in these patients was observed and the relation between gene expression and radiosensitivity was analyzed. Results: Compared with the bcl-2-negative group, the radiosensitivity of bcl-2-positive one was lower(P<0.01). The radiosensitivity of p53-positive group was slightly lower than that of the p53-negative one (P<0.05). The c-myc protein expression was not related to radiosensitivity. Conclusion: Detection and comprehensive analysis of bcl-2, c-myc and p53 protein expressions are useful in forecasting the radiotherapeutic effect on squamous cell carcinoma of esophagus

DNA repair , cell repair and radiosensitivity

International Nuclear Information System (INIS)

Zhestyanikov, V.D.

1983-01-01

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

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

Directory of Open Access Journals (Sweden)

M Emmy M Dolman

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

Enhancement of P53-Mutant Human Colorectal Cancer Cells Radiosensitivity by Flavonoid Fisetin

International Nuclear Information System (INIS)

Chen Wenshu; Lee Yijang; Yu Yichu; Hsaio Chinghui

2010-01-01

Purpose: The aim of this study was to investigate whether fisetin is a potential radiosensitizer for human colorectal cancer cells, which are relatively resistant to radiotherapy. Methods and Materials: Cell survival was examined by clonogenic survival assay, and DNA fragmentation was assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay. The effects of treatments on cell cycle distribution and apoptosis were examined by flow cytometry. Western blot analysis was performed to ascertain the protein levels of γ-H2AX, phospho-Chk2, active caspase-3, PARP cleavage, phospho-p38, phospho-AKT, and phospho-ERK1/2. Results: Fisetin pretreatment enhanced the radiosensitivity of p53-mutant HT-29 human colorectal cancer cells but not human keratocyte HaCaT cells; it also prolonged radiation-induced G 2 /M arrest, enhanced radiation-induced cell growth arrest in HT-29 cells, and suppressed radiation-induced phospho-H2AX (Ser-139) and phospho-Chk2 (Thr-68) in p53-mutant HT-29 cells. Pretreatment with fisetin enhanced radiation-induced caspase-dependent apoptosis in HT-29 cells. Fisetin pretreatment augmented radiation-induced phosphorylation of p38 mitogen-activated protein kinase, which is involved in caspase-mediated apoptosis, and SB202190 significantly reduced apoptosis and radiosensitivity in fisetin-pretreated HT-29 cells. By contrast, both phospho-AKT and phospho-ERK1/2, which are involved in cell proliferation and antiapoptotic pathways, were suppressed after irradiation combined with fisetin pretreatment. Conclusions: To our knowledge, this study is the first to provide evidence that fisetin exerts a radiosensitizing effect in p53-mutant HT-29 cells. Fisetin could potentially be developed as a novel radiosensitizer against radioresistant human cancer cells.

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.

Radiosensitizers and protectors

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

1987-01-01

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

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

International Nuclear Information System (INIS)

Liang Xiaofang; Hong Chengjiao; Zhang Baoguo

2009-01-01

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

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

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

2012-01-01

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

Radiosensitivity of four human tumor xenografts. Influence of hypoxia and cell-cell contact

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Guichard, M.; Dertinger, H.; Malaise, E.P.

1983-01-01

Contact effect (CE) and hypoxia have been studied in human tumor cell lines transplanted in athymic nude mice. Four cell lines - one melanoma (Bell) and three colorectal adenocarcinomas (HT29, HRT18, and HCT8) - were studied. Cell survival was determined with an in vivo in vitro colony-forming assay. Survival curves were obtained under three different conditions: (1) tumor cells irradiated in air-breathing mice, (2) tumor cells irradiated in animals asphyxiated for 10 min, and (3) tumor cells plated and irradiated either immediately or 5 hr later. For all cell lines, radiosensitivity appeared to be lower when cells were irradiated in vivo than when they were irradiated in vitro. Only in the case of the HCT8 tumor did the relative in vivo radioresistance seem to be linked to hypoxia; in the other cell lines, hypoxia alone could not account for the lower in vivo radiosensitivity. Our results suggest that a CE plays an important role in the response of human xenografts to irradiation

Genetic control of yeast cell radiosensitivity modification by oxygen and hypoxic sensitizers

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Zhuranovskaya, G.P.; Petin, V.G.

1984-01-01

Diploid yeast cells Saccharomyces cerevisiae ''of the wild type'', individual mutants, homozygous in rad 2 and rad 54 and double mutants, containing both these loci in homozygous state are considered to prove genetic determination of radiosensitivity modification of hypoxic cells by oxygen and electron acceptor compounds previously demonstrated on yeast cells of other genotypes. It is shown that both ''oxygen effect'' and the effect of hypoxic sensitizers depend on the activity of repair systems. The possible mechanism of participation of post-radiation restoration processes in the modification of cell radiosensitivity, is discussed

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

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Ikeuchi, Shunji

1983-01-01

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

Phase I/II Trial of Sequential Chemoradiotherapy Using a Novel Hypoxic Cell Radiosensitizer, Doranidazole (PR-350), in Patients With Locally Advanced Non-Small-Cell Lung Cancer (WJTOG-0002)

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Nishimura, Yasumasa; Nakagawa, Kazuhiko; Takeda, Koji; Tanaka, Masahiro; Segawa, Yoshihiko; Tsujino, Kayoko; Negoro, Shunichi; Fuwa, Nobukazu; Hida, Toyoaki; Kawahara, Masaaki; Katakami, Nobuyuki; Hirokawa, Keiko; Yamamoto, Nobuyuki; Fukuoka, Masahiro; Ariyoshi, Yutaka

2007-01-01

Purpose: This Phase I/II trial was conducted to assess the efficacy and safety of PR-350, a novel hypoxic cell radiosensitizer, when administered with thoracic radiation therapy (RT) after induction chemotherapy (CT) for locally advanced non-small-cell lung cancer (NSCLC). Methods and Materials: Two cycles of cisplatin (80 mg/m 2 ) and paclitaxel (180 mg/m 2 ), or carboplatin (AUC = 6) and paclitaxel (200 mg/m 2 ) were given before RT of 60 Gy in 30 fractions. In the Phase I portion, the starting dosage of PR-350 was 10 daily administrations (2000 mg/m 2 ) in combination with RT, and this number was increased in increments of 10 for successive groups to 30 doses. Results: In total, 37 patients were enrolled. In Phase I (n = 20), PR-350 could be administered 30 times with concurrent thoracic RT. Thus, in Phase II (n = 17), PR-350 was administered 30 times. The major toxicity was radiation pneumonitis, with Grade 3 or more pneumonitis noted in 6 patients (16%) including 2 with treatment-related deaths. However, no Grade 3 or more esophageal toxicity was noted, and only Grade 1 peripheral neuropathy was noted in 9 patients (24%). For all 37 patients, the median survival time (MST) and the 2-year survival rate were 15.9 months and 24%, respectively. For 18 patients receiving 21 to 30 doses of PR-350, the MST and 2-year survival rate were 20.9 months and 33%, respectively. Conclusions: Thoracic RT combined with 30 daily administrations of PR-350 after induction CT was well tolerated and promising for locally advanced NSCLC

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

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Tong Liumei; Feng Libo; Lu Xueguan; Chen Liesong; Guo Xinwei; Tian Ye

2010-01-01

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% O 2 ) or continuous hypoxia (1% O 2 ) 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, SF 2 (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)

Studies on radiosensitization of Escherichia coli cells by cis-platinum complexes

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Zimbrick, J.D.; Sukrochana, A.; Richmond, R.C.

1979-01-01

We recently reported that the antitumor drug cis-Pt(NH 3 ) 2 Cl 2 (cis-DDP) produces significant radiosensitization of anoxic E coli C cells. We have extended these studies to three other platinum drugs, all of which have been shown to be more effective antitumor drugs than cis-DDP. The drugs are: cis-dichloro bis(ethylene imine) Pt(II) (cis-DEP); cis-dichlorobicyclopentylamine Pt(II) (cis-PAD); and Pt-thymine blue (cis-PTB). Survival curve studies indicate that these drugs all produce greater anoxic radiosensitization of E coli C than cis-DDP at concentrations which are less toxic to the cells than similar concentrations of cis-DDP. If the cells are treated with any one of these drugs for two hours and then washed to remove the drug before irradiation, no detectable radiosensitization is found. We conclude that these drugs have the potential for being useful agents in combined modality therapy and that they warrant further study in mammalian systems

Evaluation of 2-amino-5-nitrothiazole as a hypoxic cell radiosensitizer

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Rockwell, S.; Mroczkowski, Z.; Rupp, W.D.

1982-01-01

The nitroheterocyclic compound 2-amino-5-nitrothiazole (ANT) was evaluated as a hypoxic radiosensitizer. Experiments with bacteria showed that this agent was similar to misonidozole in radiosensitizing activity, but was less cytotoxic and less mutagenic than misonidazole. Experiments with EMT6 tumor cells in culture showed ANT to be an effective hypoxic radiosensitizer, although slightly less active than misonidazole, and to be less cytotoxic than misonidazole. ANT was more toxic to mice than misonidazole and produced a spectrum of symptoms, including hyperactivity and agitation, different from those of misonidazole. The toxicities of ANT and misonidazole were additive. The maximum levels of ANT achieveable in the tumors after ip injection of nontoxic doses of drug were low ( -4 M) and the radiosensitization obtainable with the drug in vivo was inferior to that obtainable with misonidazole. These findings suggest that nitrothiazoles might be an interesting class of nitroheterocyclic radiosensitizers, but that molecules with increased solubility and improved pharmacokinetics would be necessary for efficacy in vivo

THERMAL RADIOSENSITIZATION IN HEAT-SENSITIVE AND RADIATION-SENSITIVE MUTANTS OF CHO CELLS

NARCIS (Netherlands)

KAMPINGA, HH; KANON, B; KONINGS, AWT; STACKHOUSE, MA; BEDFORD, JS

Recently, it has been hypothesized (Iliakis and Seaner 1990) that DNA double-strand break (dsb) repair proficiency is a prerequisite for heat radiosensitization on the basis of the finding that the radiosensitive and dsb-repair-deficient mutant xrs-5 cell line shows no significant heat-induced

HAP1 gene expression is associated with radiosensitivity in breast cancer cells

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Wu, Jing; Zhang, Jun-ying; Yin, Li; Wu, Jian-zhong; Guo, Wen-jie; Wu, Jian-feng; Chen, Meng; Xia, You-you; Tang, Jin-hai; Ma, Yong-chao; He, Xia

2015-01-01

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

A study on the toxicity of three radiosensitizers on retinoblastoma cells by MTT assay

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

1994-01-01

The toxicity of three radiosensitizers BSO, CM and RSU-1069 on retinoblastoma cells was determined and the efficiency of in vitro MTT assay on drug-screening for retinoblastoma was also evaluated. The results showed that the MTT assay is very useful. The toxicity of radiosensitizers on retinoblastoma cells is dependent on cell line characteristics, drug concentration and time of exposure to it

Cabazitaxel-induced stabilization of microtubules enhances radiosensitivity in ovarian cancer cells

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Charles eKunos

2013-09-01

Full Text Available Background: Up to 40% of women with ovarian cancer have short disease-free intervals due to molecular mechanisms of chemotherapy resistance. New therapeutic strategies are sought. Ovarian cancers are sensitive to radiochemotherapy. The taxane cabazitaxel (XRP6258, Jevtana promotes tubulin assembly and stabilizes microtubules against depolymerization in cells, acting similarly in mechanism to paclitaxel. Here, sequences of cabazitaxel-radiation co-administration are tested for drug-alone cytotoxicity and optimal radiosensitization.Methods: SKOV3, OVCAR3, and TOV-112D ovarian cancer cells were administered cabazitaxel 24 h before (first, 18 h before (second, together (third, or 24 h after (fourth a single radiation dose, and then, investigated by clonogenic assay and flow cytometric assays. Radiation dose-cell survival data were fitted by two-stage multivariate analyses of variance. High content flow cytometry partitioned cabazitaxel effects into G2-phase versus M-phase events by DNA content, cyclin A2, and phospho-S10-histone H3 (PHH3. Paclitaxel served as a comparator. Findings: Cabazitaxel cytotoxicity and radiosensitization were dose dependent. Cabazitaxel added 24 h before radiation was the most lethal schedule. DNA content measurements by flow cytometry showed that cabazitaxel-treated cells accumulated in the radiosensitive G2/M 4C DNA complement compartment. Cytometry also showed that surviving cabazitaxel-induced cell cycle arrested cells resolve the arrest by entering 4C or by 8C DNA complement cell cycles.Interpretation: The radiosensitizing effect of cabazitaxel was schedule dependent, due to cell cycle redistribution, and best when cabazitaxel was given 24 h before radiation. Clinical trials of administering both cabazitaxel and radiation should be explored in women with chemoresistant ovarian cancer. Funding: Case Comprehensive Cancer Center and Sanofi-Aventis

Cellular radiosensitivity of small-cell lung cancer cell lines

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Krarup, Marianne; Poulsen, Hans Skovgaard; Spang-Thomsen, Mogens

1997-01-01

Purpose: The objective of this study was to determine the radiobiological characteristics of a panel of small-cell lung cancer (SCLC) cell lines by use of a clonogenic assay. In addition, we tested whether comparable results could be obtained by employing a growth extrapolation method based on the construction of continuous exponential growth curves. Methods and Materials: Fifteen SCLC cell lines were studied, applying a slightly modified clonogenic assay and a growth extrapolation method. A dose-survival curve was obtained for each experiment and used for calculating several survival parameters. The multitarget single hit model was applied to calculate the cellular radiosensitivity (D 0 ), the capacity for sublethal damage repair (D q ), and the extrapolation number (n). Values for α and β were determined from best-fit curves according to the linear-quadratic model and these values were applied to calculate the surviving fraction after 2-Gy irradiation (SF 2 ). Results: In our investigation, the extrapolation method proved to be inappropriate for the study of in vitro cellular radiosensitivity due to lack of reproducibility. The results obtained by the clonogenic assay showed that the cell lines studied were radiobiologically heterogeneous with no discrete features of the examined parameters including the repair capacity. Conclusion: The results indicate that SCLC tumors per se are not generally candidates for hyperfractionated radiotherapy

Targeting Mcl-1 for Radiosensitization of Pancreatic Cancers

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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.

Radiation could induce p53-independent and cell cycle - unrelated apoptosis in 5-fluorouracil radiosensitized head and neck carcinoma cells

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Didelot, C.; Mirjolet, J.F.; Barberi-Heyob, M.; Ramacci, C.; Merlin, J.L.

2002-01-01

The effect of chemoresistance induction in radio sensitivity and cellular behavior after irradiation remains misunderstood. This study was designed to understand the relationship between radiation-induced cell cycle arrest, apoptosis, and radiosensitivity in KB cell line and KB3 subline selected after 5-fluorouracil (5FU) exposure. Exposure of KB cells to 5FU led to an increase in radiosensitivity. G 2 /M cell cycle arrest was observed in the two cell lines after irradiation. The radioresistant KB cell line reached the maximum arrest two hours before KB3. The cellular exit from this arrest was found to be related to the wild type p53 protein expression induction. After irradiation, only KB3 cell line underwent apoptosis. This apoptosis induction seemed to be independent of G 2 /M arrest exit, which was carried out later. The difference in radiosensitivity between KB and KB3 subline may result therefore from both a difference in apoptosis induction and a difference in G 2 /M arrest maximum duration. Moreover, 5FU exposure has led to an increase in constitutive p53 protein expression, which may be associated with an increase in basal apoptosis cell fraction. Given the existing correlation between radiosensitivity and the percentage of basal apoptosis. the constitutive p53 protein expression may be related to intrinsic radiosensitivity in our cellular model. (author)

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

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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.

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

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

2015-01-01

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

Different radiosensitivities of mast-cell precursors in the bone marrow and skin of mice

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Kitamura, Y.; Yokoyama, M.; Sonoda, T.; Mori, K.J.

1983-01-01

Although tissue mast cells are derived from the bone marrow, some descendants of bone marrow-derived precursors retain the ability to proliferate and differentiate into mast cells even after localization in the skin. The purpose of the present study was to determine the D0 values for mast-cell precursors in the bone marrow and those localized in the skin. Bone marrow cells were removed from (WB X C57BL/6)F1-+/+ mice after various doses of irradiation and injected into the skin of the congenic W/Wv mice which were genetically without mast cells. Radiosensitivity of mast-cell precursors in the bone marrow was evaluated by determining the proportion of the injection sites at which mast cells did not appear. For the assay of the radiosensitivity of mast-cell precursors localized in the skin, pieces of skin were removed from beige C57BL/6 (bgJ/bgJ. Chediak-Higashi syndrome) mice after various doses of irradiation and grafted onto the back of the normal C57BL/6 mice. Radiosensitivity of mast-cell precursors in the skin was evaluated by determining the decrease of beige-type mast cells which possessed giant granules. Mast-cell precursors in the bone marrow were much more radiosensitive than those localized in the skin. D0 value was about 100 rad for the former and about 800 rad for the latter

Differential Radiosensitizing Potential of Temozolomide in MGMT Promoter Methylated Glioblastoma Multiforme Cell Lines

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Nifterik, Krista A. van; Berg, Jaap van den; Stalpers, Lukas J.A.; Lafleur, M. Vincent M.; Leenstra, Sieger; Slotman, Ben J.; Hulsebos, Theo J.M.; Sminia, Peter

2007-01-01

Purpose: To investigate the radiosensitizing potential of temozolomide (TMZ) for human glioblastoma multiforme (GBM) cell lines using single-dose and fractionated γ-irradiation. Methods and Materials: Three genetically characterized human GBM cell lines (AMC-3046, VU-109, and VU-122) were exposed to various single (0-6 Gy) and daily fractionated doses (2 Gy per fraction) of γ-irradiation. Repeated TMZ doses were given before and concurrent with irradiation treatment. Immediately plated clonogenic cell-survival curves were determined for both the single-dose and the fractionated irradiation experiments. To establish the net effect of clonogenic cell survival and cell proliferation, growth curves were determined, expressed as the number of surviving cells. Results: All three cell lines showed MGMT promoter methylation, lacked MGMT protein expression, and were sensitive to TMZ. The isotoxic TMZ concentrations used were in a clinically feasible range of 10 μmol/L (AMC-3046), 3 μmol/L (VU-109), and 2.5 μmol/L (VU-122). Temozolomide was able to radiosensitize two cell lines (AMC 3046 and VU-122) using single-dose irradiation. A reduction in the number of surviving cells after treatment with the combination of TMZ and fractionated irradiation was seen in all three cell lines, but only AMC 3046 showed a radiosensitizing effect. Conclusions: This study on TMZ-sensitive GBM cell lines shows that TMZ can act as a radiosensitizer and is at least additive to γ-irradiation. Enhancement of the radiation response by TMZ seems to be independent of the epigenetically silenced MGMT gene

Survey of radiosensitivity in a variety of human cell strains

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Arlett, C.F.; Harcourt, S.A.

1980-03-01

Gamma-ray sensitivity for cell killing was assayed in 54 human cell strains, including some derived from individuals suffering from certain hereditary diseases. The overall range of Do values in this study was 38 to 180 rads, indicating a considerable range of variability in humans. The normal sensitivity was described by a range of Do values of 97 to 180 rads. All ten ataxia telangiectasia cell strains tested proved radiosensitive and gave a mean Do value of 57 +- 15 (S.E.) rads, and these represent the most radiosensitive human skin fibroblasts currently available. Representative cell strains from familial retinoblastoma, Fanconi's anemia, and Hutchinson-Gilford progeria occupied positions of intermediate sensitivity, as did one of two ataxia telangiectasia heterozygotes. Six xeroderma pigmentosum cell strains together with two Cockayne's syndrome cell strains (all known to be sensitive to ultraviolet light) fell into the normal range, indicating an absence of cross-sensitivity between ultraviolet light and gamma-irradiation.

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

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

2016-01-01

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

Effect of 17-AAG on radio-sensitivity of HeLa and V79 cells

International Nuclear Information System (INIS)

Pan Yanling; Hong Chengjiao; Zhang Baoguo

2010-01-01

In order to investigate the radio-sensitizing effect of 17-AAG, an inhibitor of Heat Shock Protein 90, on human Uterine Cervix Cancer HeLa and V79 cells, Clonogenic assay was used to observe the cell survival rate. The results show that 17-AAG can decrease obviously (p 0.05). This indicates that 17-AAG may enhance the radio-sensitivity of the HeLa cell line and has no effect on the V79 cell line. (authors)

Radiosensitizers: rationale and potential

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Brown, J.M.

1981-01-01

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

Radiosensitivity of hemopoietic stem cells on cloning in bone marrow and spleen

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Shvets, V.N.; Shafirkin, A.V.

1979-01-01

It was shown that population of stem cells from bone marrow of mice is heterogenous by radiosensitivity. A 55%-survival of CFU is exponential function of radiation dose (D 0 -9 rad). A dose-effect curve for radioresistant part of the population (D 0 =180 rad) is sygmoid (Dsub(q)=130 rad). Radiosensitive CFU are suggested to represent a primarily committed fraction of half-semi cells, and radioresistant CFU are referable to a pool of pluripotent stem cells. Heterogenous nature of CFU population is proved with different modifications of radiation effect and interactions of CFU with T-lymphocytes

Radiosensitization by overexpression of the nonphosphorylation form of IκB-α in human glioma cells

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Honda, Naoko; Yagi, Kasumi; Ding, Gui-Rong; Miyakoshi, Junji

2002-01-01

To assess the role of NF-κB in cellular radiosensitivity, we constructed mutated IκB expression plasmids for SY-IκB (with mutations at residues of 32, 36 and 42) expression in human malignant glioma cells (radiosensitive MO54 and radioresistant T98 cells), giving respective cell types referred to as MO54-SY4 and T98-SY14. Both of the clones expressing SY-IκB became radiosensitive, compared with the parental MO54 and T98 cells. A treatment with herbimycin A or genistein did not change the radiosensitivity of cells expressing SY-IκB, but made both the MO54 and T98 parental cells more sensitive to ionizing radiation. A treatment with TNF-α induced DNA fragmentation and apoptosis in cells expressing SY-IκB, but not in MO54 and T98 cells. The survival after X-ray exposure of the parental MO54 cells was slightly increased by a TNF-α treatment, but that of the parental T98 cells did not change. The change in sensitivity to ultra-violet (UV) radiation and adriamycin in MO54-SY4 cells was very similar to that for X-ray sensitivity, but no change was observed in T98-SY14 cells. Significant sublethal damage repair was observed in T98 cells, whereas MO54 cells showed little repair activity. The expression of p53 was enhanced in the parental MO54 cells, while the p53 levels in the MO54-SY4, and in the parent and clonal T98 cells, did not change. Our data suggest that the serine and tyrosine phosphorylation of IκB-α may play a role in determining the radiosensitivity of malignant glioma cells. (author)

Alterations in gene expression profiles between radioresistant and radiosensitive cell lines

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Zhou Fuxiang; Zhou Yunfeng; Xie Conghua; Dai Jing; Cao Zhen; Yu Haijun; Liao Zhengkai; Luo Zhiguo

2007-01-01

Objective: To study the-difference of gene expressions by the contrastive model including the cells with same pathological origin and genetic background, but definitely different radioresponse, and to find the main molecular targets related to radiosensitivity. Methods: Human larynx squamous carcinoma cell, Hep -2 was irradiated with dose of 637 cGy repeatedly to establish a radioresistant daughter cell line. The radiobiology characteristics were obtained using clone forming assay. The difference of gene expression between parent and daughter cells was detected by cDNA microarray using two different arrays including 14000 genes respectively. Results: A radioresistant cell strain Hep-2R was isolated from its parental strain Hep-2 cell. The SF 2 , D 0 , α, β for Hep-2R cell line were 0.6798, 3.24, 0.2951 and 0.0363, respectively, while 0.4148, 2.06, 0.1074 and 0.0405 for Hep-2, respectively (for SF 2 , χ 2 =63.957, P<0.001). Compared with Hep-2 cells, the expressions of 41 genes were significantly altered in the radioresistant Hep-2R cells, including 22 genes up-regulated and 19 genes down-regulated, which were involved in DNA repair, regulation of the cell cycle, cell proliferation, cytoskeleton, protein synthesis, cellular metabolism and especially apoptosis which is responsible for the different radiosensitivity between these two larynx cancer cells. The telomere protection protein gene, POT1, was the mostly up-regulated by 3.348 times. Conclusions: There is difference of gene expression between the radioresistant contrastive models. POT1 gene may be the target of radiosensitization. (authors)

Mechanisms of oxygen radiosensitization in CHO cells

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Whillans, D.W.

1981-01-01

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

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

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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.)

Comparison of radiosensitivities of human autologous normal and neoplastic thyroid epithelial cells

International Nuclear Information System (INIS)

Miller, R.C.; Kopecky, K.J.; Hiraoka, T.; Ezaki, H.; Clifton, K.H.

1986-01-01

Studies were conducted to examine differences between the radiosensitivities of normal and neoplastic epithelial cells of the human thyroid. Freshly excised thyroid tissues from the tumours of eight patients with papillary carcinoma (PC) and five with follicular adenoma (FA) were cultured in vitro separately from normal thyroid tissue obtained from the surgical margins of the same patients. Plating efficiency of unirradiated control tissue was lower, on average for tumour tissue compared with normal tissue. Radiosensitivity, measured by the 37% inactivation dose D 0 , was greater for carcinoma tissue than for normal tissue in seven out of eight PC cases. Adenomatous tissue was less radiosensitive than normal tissue in four out of five FA cases. This is the first report comparing the radiosensitivity of autologous normal and abnormal epithelial tissue from the human thyroid. (author)

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

Science.gov (United States)

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

2016-01-01

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

G{sub 2} radiosensitivity of cells derived from cancer-prone individuals

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Darroudi, F.; Vyas, R.C.; Vermeulen, S.; Natarajan, A.T. [J.A. Cohen Institute of Radiopathology and Radiation Protection, Interuniversity Institute, Leiden (Netherlands)

1995-04-01

The potential of enhanced chromatid damage, observed after X-irradiation of G{sub 2} phase, has been used to detect individuals genetically predisposed to cancer, utilising fibroblasts/lymphocytes from these patients as well as fibroblasts derived from human tumours. Fibroblasts and/or lymphocyte samples of two autosomal recessive syndromes (xeroderma pigmentosum (XP), Fanconi`s anaemia (FA)) and one congenital or acquired disorder, aplastic anaemia (AA), were employed for the G{sub 2} radiosensitivity assay. In addition, we have estimated the frequencies of spontaneously occurring chromosomal aberrations as well as G{sub 2} radiosensitivity of eight samples of fibroblasts/fibroblast-like cells (two normal, two colorectal carcinoma, two Wilms` tumour, one retinoblastoma and one polyposis coli), and three samples of lymphocytes (two normal and one from a lymphoma patient). The results obtained indicate that there were no differences between fibroblast cells derived from patients or tumours, except FA patients, in the frequency of spontaneously occurring chromosomal aberrations when compared to normal cells. Following X-irradiation we did not observe any significantly increased G{sub 2} radiosensitivity in FA and XP cells. Lymphocytes from AA and lymphoma patients, and all tumour cell lines except retinoblastoma, responded with increased frequencies of aberrations following G{sub 2} X-irradiation in comparison to cells derived from normal individuals. In our hands, the G{sub 2} sensitivity assay could not always discriminate cells from cancer-prone individuals from those of controls.

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

Science.gov (United States)

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

2017-10-01

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

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

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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

Effect of misonidazole on radiosensitivity of Ehrlich ascites tumor cells

International Nuclear Information System (INIS)

Takeuchi, Hiroshi

1986-01-01

The effect of Misonidazole on radiosensitivity of Ehrlich ascites tumor cells was studied in vivo. Ehrlich ascites tumor cells growing intraperitoneally (ICR/SIC mice) for either 1, 4, 6 or 10 days were irradiated in vivo (whole body irradiation) with or without Misonidazole. Immediately after irradiation tumor cells were transplanted intraperitoneally into new animals. Four days later, the propagated surviving cells were removed and counted for analyses. Enhancement ratio of Misonidazole at the surviving fraction of 0.1 were 1.0 (for 1-day-old), 1.3 (for 4-day-old), 1.9 (for 6-day-old), 1.9 (for 10-day-old) and 2.8 (for anoxic cells) respectively. The gradual increase of the enhancement ratio of the ascites tumore cells during intraperitoneal growth from 1 through 10 days might be attributed to an increase of hypoxic tumor cells. Cytotoxicity was not observed at 0.1 mg per gram body weight of Misonidazole but was at 1 mg per gram body weight of Misonidazole in 6-day-old and 10-day-old Ehrlich ascites tumor cells which were supposed to contain hypoxic cells. These results suggest that Misonidazole may prove an effective radiosensitizer for hypoxic tumor cells. (author)

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

International Nuclear Information System (INIS)

Sun Jianxiang; Sun Weijian; Sui Jianli; Zhou Pingkun

2008-01-01

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 60 Co 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 (D 0 or SF 2 ). 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)

The influence of autologous tumor fibroblasts on the radiosensitivity of squamous cell carcinoma megacolonies

International Nuclear Information System (INIS)

Kummermehr, Johann; Malinen, Eirik; Freykowski, Sabine; Sund, Malte; Trott, Klaus-Ruediger

2001-01-01

Purpose: To study the influence of tumor fibroblasts on radiosensitivity and stem cell fraction of tumor cells in squamous cell carcinoma megacolonies by determining colony cure and clonogen survival. Methods and Materials: Murine squamous cell carcinoma cells (AT478c) grown as flat but multilayered megacolonies were co-cultured with pre-irradiated tumor fibroblasts derived from the same carcinoma, and irradiated with 1, 2, 4, or 8 fractions. Recurrent clones and their growth pattern in situ were recorded. From megacolony cure data and clonogen survival data, the clonogen number and the parameters of cellular radiosensitivity were calculated. Results: The curability of the co-cultured megacolonies, as determined by TCD50 values, was significantly increased compared to the megacolonies without fibroblasts (p<0.01). Both the megacolony cure and clonogen survival data suggested a decrease of the clonogen fraction in the co-cultured megacolonies. Conclusion: The presence of tumor fibroblasts increases megacolony radiosensitivity. This is due to a decrease in the fraction of clonogens in the tumor megacolony, apparently caused by a downregulation of the stem cell fraction of the tumor cells

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

Science.gov (United States)

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

2017-05-10

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

Chromosomal radiosensitivity during the G2 cell-cycle period of skin fibroblasts from individuals with familial cancer

International Nuclear Information System (INIS)

Parshad, R.; Sanford, K.K.; Jones, G.M.

1985-01-01

The authors reported previously that human cells after neoplastic transformation in culture had acquired an increased susceptibility to chromatid damage induced by x-irradiation during the G2 phase of the cell cycle. Evidence suggested that this results from deficient DNA repair during G2 phase. Cells derived from human tumors also showed enhanced G2-phase chromosomal radiosensitivity. Furthermore, skin fibroblasts from individuals with genetic diseases predisposing to a high risk of cancer, including ataxia-telangiectasia, Bloom syndrome, Fanconi anemia, and xeroderma pigmentosum exhibited enhanced G2-phase chromosomal radiosensitivity. The present study shows that apparently normal skin fibroblasts from individuals with familial cancer--i.e., from families with a history of neoplastic disease--also exhibit enhanced G2-phase chromosomal radiosensitivity. This radiosensitivity appears, therefore, to be associated with both a genetic predisposition to cancer and a malignant neoplastic state. Furthermore, enhanced G2-phase chromosomal radiosensitivity may provide the basis for an assay to detect genetic susceptibility to cancer

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

International Nuclear Information System (INIS)

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

2009-01-01

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

The HSP90 Inhibitor Ganetespib Radiosensitizes Human Lung Adenocarcinoma Cells

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Roberto Gomez-Casal

2015-05-01

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

Cell proliferation and radiosensitivity of cow lymphocytes in culture

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Modave, C.; Fabry, L.; Leonard, A.

1982-01-01

The harlequin-staining technique has been used to study, after PHA-stimulation, the cell proliferation of cow lymphocytes in culture and to assess the radiosensitivity in first mitosis cells. At the 48 h fixation time, only 34% of the cells are in first mitosis whereas 55% are already in second and 11% in third mitosis. The exposure of cow lymphocytes to 200 rad X-rays result in the production of 16% dicentric chromosomes in first mitosis cells [fr

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

International Nuclear Information System (INIS)

Sun Baosheng; Liu Shixin; Wang Tiejun; Liu Linlin; Huang Guomin; Gong Shouliang

2008-01-01

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 (P 0 and SER D q ) 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)

Retention of the In Vitro Radiosensitizing Potential of Gemcitabine Under Anoxic Conditions, in p53 Wild-Type and p53-Deficient Non-Small-Cell Lung Carcinoma Cells

International Nuclear Information System (INIS)

Wouters, An; Pauwels, Bea; Lambrechts, Hilde A.J.; Pattyn, Greet G.O.; Ides, Johan; Baay, Marc; Meijnders, Paul; Peeters, Marc; Vermorken, Jan B.; Lardon, Filip

2011-01-01

Purpose: Whereas radiosensitization by gemcitabine is well studied under normal oxygen conditions, little is known about its radiosensitizing potential under reduced oxygen conditions. Therefore, the present study evaluated the impact of anoxia on gemcitabine-mediated radiosensitization. Methods and Materials: The clonogenic assay was performed in three isogenic A549 cell lines differing in p53 status (24 h, 0-15 nM gemcitabine, 0-8 Gy irradiation, normoxia vs. anoxia). Using radiosensitizing conditions, cells were collected for cell cycle analysis and apoptosis detection. Results: Whereas wild-type p53 A549-LXSN cells were more sensitive to radiation than p53-deficient A549-E6 cells, both cell lines showed similar radiosensitization by gemcitabine under normoxia and anoxia. Independent of p53 functionality, gemcitabine was able to overcome anoxia-induced G 0/1 arrest and established an (early) S phase block in normoxic and anoxic cells. The percentage early and late apoptotic/necrotic cells increased with the gemcitabine/radiation combination, with a significant difference between A549-LXSN and A549-E6. Conclusions: This study is the first to show that gemcitabine retains its radiosensitizing potential under low oxygen conditions. Although radiosensitization was observed in both p53 wild-type and p53-deficient cells, p53 status might influence induction of apoptosis after gemcitabine/radiation treatment, whereas no effect on cell cycle progression was noticed.

Radiosensitivity and genes

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

1995-07-01

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

Radiosensitivity and genes

International Nuclear Information System (INIS)

Hu Qiyue; Lun Mingyue

1995-07-01

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

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

International Nuclear Information System (INIS)

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

2010-01-01

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

Radiosensitizing potential of gemcitabine (2',2'-difluoro-2'-deoxycytidine) within the cell cycle in vitro

International Nuclear Information System (INIS)

Latz, Detlev; Fleckenstein, Katharina; Eble, Michael; Blatter, Johannes; Wannenmacher, Michael; Weber, Klaus J.

1998-01-01

Purpose: Gemcitabine (2',2'-difluorodeoxycytidine; dFdCyd) is a new deoxycitidine analog which exhibits substantial activity against solid tumors and radiosensitizing properties in vitro. To examine cell cycle-specific effects of a combined treatment with gemcitabine and radiation, the in vitro clonogenic survival of two different cell lines was measured for cells from log-phase culture, G1 and S-phase cells. Methods and Materials: Chinese hamster (V79) and human colon carcinoma (Widr) cells were exposed to different radiation doses and for different points of time relative to gemcitabine treatment (2 h). Experiments were also carried out with different cell-cycle populations obtained after mitotic selection (V79) or after serum stimulation of plateau-phase cells (Widr). The resulting survival curves were analyzed according to the LQ model, and mean inactivation doses (MID) and the cell cycle-specific enhancement ratios (ER) were calculated from the survival curve parameters. Results: Effectiveness of combined treatment of log-phase cells was greatest when cells were irradiated at the end of the gemcitabine exposure [ER: 1.28 (V79), 1.24 (Widr)]. For later times after the removal of the drug, radiosensitization declined, approaching independent toxicity. From the time course of interactive-type damage decay half-life values of 75 min (V79) and 92 min (Widr) were derived. Gemcitabine did not radiosensitize G1 Widr cells or V79 cells from the G1/S border, but substantial radiosensitization was observed for the S-phase cell preparations [ER: 1.45 (V79-lateS), 1.57 (Widr)]. Conclusions: Treatment of cells with gemcitabine immediately before irradiation eliminates, or at least greatly reduces, the variation in radiosensitivity during the cell cycle that is manifested by radioresistance during S phase. This reversal of S-phase radioresistance could imply that gemcitabine interferes with the potentially lethal damage repair/fixation pathway. Other approaches have been

Relation between number of hemopoietic stem cells in newborn mice and their radiosensitivity

International Nuclear Information System (INIS)

Sutter, T.; Maes, J.; Gerber, G.B.; Leonard, A.

1985-01-01

Fractionation of a radiation exposure causes greater damage in newborn mice than a single application since it induces radioresistant foetal hemopoietic stem cells to differentiate prematurely to more radiosensitive adult ones. In the present investigation, it was studied whether other agents that give rise to extensive stem cell destruction also lead to such a change in radiosensitivity. Indeed, treatment with cytostatic drugs which reduces the number of spleen colony forming units (CFU-s) and total cells also diminished the D 0 value of the surviving cells 3 days later. Adriamycin was most effective in causing damage to hemopoietic stem cells and in inducing micronuclei in bone marrow; it also had the most marked action on the D 0 of the surviving stem cells. (orig.)

Radiosensitivity of amphibia

Energy Technology Data Exchange (ETDEWEB)

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

1975-04-01

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

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

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...

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

International Nuclear Information System (INIS)

Sørensen, Brita Singers; Busk, Morten; Olthof, Nadine; Speel, Ernst-Jan; Horsman, Michael R.; Alsner, Jan; Overgaard, Jens

2013-01-01

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 FaDu DD , 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

Radiosensitivity of yeast cells as a function of radiation LET

International Nuclear Information System (INIS)

Lobachevskij, P.N.; Krasavin, E.A.

1988-01-01

A model is proposed for interpreting the radiosensitivity of yeast cells as a function of linear energy transfer (LET) of ionizing radiation. The model takes into account the role of repair processes in sensitivity of yeast cells to ionizing radiation of different LET. Two types of repair are discussed: (1) a nonspecific repair (characteristic of both haploid and diploid cells), and (2) a diploid - soecific repair (characteristic of diploid cells only)

Lethality of radiation-induced chromosome aberrations in human tumour cell lines with different radiosensitivities.

Science.gov (United States)

Coco-Martin, J M; Ottenheim, C P; Bartelink, H; Begg, A C

1996-03-01

In order to find an explanation for the eventual disappearance of all chromosome aberrations in two radiosensitive human tumour cell lines, the type and stability of different aberration types was investigated in more detail. To classify the aberrations into unstable and stable types, three-colour fluorescence in situ hybridization was performed, including a whole-chromosome probe, a pancentromere probe, and a stain for total DNA. This technique enables the appropriate classification of the aberrations principally by the presence (stable) or not (unstable) of a single centromere per chromosome. Unstable-type aberrations were found to disappear within 7 days (several divisions) in the two radiosensitive and the two radioresistant tumour lines investigated. Stable-type aberrations were found to remain at an approximately constant level over the duration of the experiment (14 days; 8-10 divisions) in the two radioresistant lines. In contrast, the majority of these stable-type aberrations had disappeared by 14 days in the two radiosensitive lines. The previous findings of disappearance of total aberrations in radiosensitive cells was therefore not due to a reduced induction of stable-type aberrations, but the complete disappearance of cells with this aberration type. These results could not be explained by differences in apoptosis or G1 blocks. Two possible explanations for these unexpected findings involve non-random induction of unstable-type aberrations, or lethality of stable-type aberrations. The results suggest caution in the use of stable-type aberration numbers as a predictor for radiosensitivity.

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

Science.gov (United States)

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

2014-01-01

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

Radiosensitization of hypoxic bacterial cells by nitroimidazoles of low lipophilicity: steady-state and rapid-mix studies

International Nuclear Information System (INIS)

Anderson, R.F.; Patel, K.B.; Sehmi, D.S.

1981-01-01

Radiosensitization of hypoxic bacterial cells by five 2-nitroimidazoles, with similar reduction potentials to misonidazole but having lower lipophilicites, has been measured in Escherichia coli AB 1157 and Streptococcus lactis 712. Sensitization efficiency progressively decreased with decreasing lepophilicity in E. coli but not in S. lactis. This difference is discussed in terms of the differing membrane properties of the two bacteria; E. coli resembled a multicompartment model, as would also be expected with mammalian cells. Rapid-mix experiments are described which show that the radiosensitization observed after experiments are described which show that the radiosensitization observed after preirradiation contact times between ca. 3 and 30 msec is dependent on the lipophilicity of the sensitizer, higher lipophilicity resulting in a lower contact time being required for radiosensitization. This result and the observation that a highly lipophilic compound affects only half the full oxygen enhancement level after short contact times suggest that part of the sensitization process occurs in a lipophilic compartment of the cell

Radiosensitivity of cultured insect cells: II. Diptera

International Nuclear Information System (INIS)

Koval, T.M.

1983-01-01

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

Radiosensitivity of human lymphocytes and thymocytes

International Nuclear Information System (INIS)

Kwan, D.K.; Norman, A.

1977-01-01

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

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

International Nuclear Information System (INIS)

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

2014-01-01

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

Genetic control of the radiosensitivity of lymphoid cells for antibody formation ability in mice

International Nuclear Information System (INIS)

Okumoto, Masaaki; Mori, Nobuko; Esaki, Kozaburo; Imai, Shunsuke; Haga, Satomi; Hilgers, Jo; Takamori, Yasuhiko.

1994-01-01

To analyze the genetic basis of the relationship between the radiosensitivity of the immune response and radiation lymphomagenesis, we examined the radiosensitivity of lymphoid cells for antibody formation in BALB/cHeA, STS/A, F 1 hybrids, and their recombinant inbred mouse strains. The decrease in the number of plaque-forming spleen cells in BALB/cHeA mice exposed to 3 Gy X-irradiation was more than tenfold that in STS/A mice. The phenotype of radioresistance was dominant over sensitivity. The coincidence between the strain distribution patterns of the genetic markers and radiosensitivities of antibody formation in the various recombinant inbred strains was in the region with the lgh locus on chromosome 12. There was obvious difference between the patterns in the region containing the lfa locus on chromosome 4 which has been shown to be related to the incidence of radiation-induced lymphomas. These results indicate that the region on chromosome 12 may contain major gene(s) related to radiosensitivity for antibody formation. (author)

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

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)

Sebastià, N.; Montoro, A.; Hervás, D.; Pantelias, G.; Hatzi, V.I.; Soriano, J.M.; Villaescusa, J.I.

2014-01-01

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

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

International Nuclear Information System (INIS)

Wazer, D.E.; Joyce, M.; Jung, L.; Band, V.

1993-01-01

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

Effect of BRCA1 on radiosensitivity of different lung cancer cells

International Nuclear Information System (INIS)

Zhang Huiwen; Wang Miao; Wang Yansu; Ren Hang; Xu Jiaying; Jiao Yang; Fan Saijun; Meng Qinghui

2011-01-01

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)

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

International Nuclear Information System (INIS)

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

2008-01-01

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

Comparison of radiosensitivity between tumor and normal tissue in terms of cell population kinetics

International Nuclear Information System (INIS)

Sugahara, Tsutomu; Utsumi, Hiroshi

1975-01-01

Puck and Marcus in 1956 established the in vitro colony formation of mammalian cells and demonstrated a dose-survival curve of mammalian cells well fitted to the target theory. Since then almost all of the work on the radiosensitivity of malignant and normal cells has been based on the reproductive integrity of cells. However, in the author's laboratory, a recent work was done on the effect of ionizing radiation on the differentiative trait, using clonal cell cultures developed by Coon (1966) in chick embryonic cartilage cells. This work demonstrated clearly that the differentiative trait is more radiosensitive than is reproduction. Based on this finding a new compartment model is proposed for a cell renewal system which demonstrates the difference between normal and malignant tissue. (author)

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

International Nuclear Information System (INIS)

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

2011-01-01

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

Daily variation in radiosensitivity of circulating blood cells and bone marrow cell density in mice

International Nuclear Information System (INIS)

Tabatabai, R.N.

1984-01-01

Mice on a 12/12 light/dark cycle were bled during a twenty-four hour period each week for eight weeks to establish daily values of circulating blood cells. No significant daily variation was found in total red blood cells, hematocrit, or percentage of reticulocytes. A significant (P < 0.001) daily variation was found in total white blood cells, with the minimum occurring at 8 PM and the maximum occurring during the daylight hours from 8 a.m. to 2 p.m. Mice were then exposed to 0 R, 20 R, 50 R, or 100 R of x-radiation to determine what dose significantly reduces the total white cell count in circulating blood. It was found that 100 R significantly (P < .05) reduces the total white cell count over a four week period post-exposure. To determine if circulating blood cells and bone marrow cells show a diurnal radiosensitivity, mice were exposed to 100 R or 200 R of x-radiation at noon or midnight. Hematocrits, reticulocyte and white blood cell counts, daily white blood cell rhythm, and bone marrow cell density indicate that these mice were more radiosensitive at night

Development of Radiosensitizer using farnesyltransferase inhibitors

Energy Technology Data Exchange (ETDEWEB)

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

1999-03-01

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

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)

Bueren, J.A.; Nieto, M.

1983-01-01

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

Cell kinetic and radiosensitivity of PHA stimulated goat lymphocytes

International Nuclear Information System (INIS)

Debuyst, B.; Rosenthal, M.; Leonard, A.

1982-01-01

The harlequin-staining method has been used to study the cell kinetic of goat peripheral blood lymphocytes stimulated by phytohemagglutinin and to assess their radiosensitivity. At 48 h, the standardized culture time employed for human lymphocytes, 71% of the goat lymphocytes are in first mitosis, 23% are in second mitosis and 5% in third. Irradiation with 200 rads X-rays induces an average of 24,5 dicentric chromosomes per hundred cells in first mitosis [fr

The radiosensitivity of spermatogonial stem cells in C3H/101 F1 hybrid mice

International Nuclear Information System (INIS)

Van der Meer, Yvonne; De Rooij, Dirk G.; Cattanach, Bruce M.

1993-01-01

The radiosensitivity of spermatogonial stem cells of C3H/HeHx101/H F 1 hybrid mice was determined by counting undifferentiated spermatogonia at 10 days after X-irradiation. During the spermatogenic cycle, differences in radiosensitivity were found, which were correlated with the proliferative activity of the spermatogonial stem cells. In stage VIII irr , during quiescence, the spermatogonial stem cells were most radiosensitive with a D 0 of 1.4 Gy. In stages XI irr -V irr , when the cells were proliferatively active, the D 0 was about 2.6 Gy. Based on the D 0 values for sensitive and resistant spermatogonia and on the D 0 for the total population, a ratio of 45:55% of sensitive to resistant spermatogonial stem cells was estimated for cell killing. When the present data were compared with data on translocation induction obtained in mice of the same genotype, a close fit was obtained when the translocation yield (Y; in % abnormal cells) after a radiation dose D was described by Y=e τD , with τ=1 for the sensitive and τ=0.1 for the resistant spermatogonial stem cells, with a maximal e τD of 100

Predisposition to cancer and radiosensitivity

International Nuclear Information System (INIS)

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

2000-01-01

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

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

Science.gov (United States)

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

2018-04-01

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

Radiosensitivity of human haematopoietic stem/progenitor cells

International Nuclear Information System (INIS)

Kato, Kengo; Kashiwakura, Ikuo; Omori, Atsuko

2013-01-01

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)

Radiosensitivity and TP 53, EGFR amplification and LOH10 analysis of primary glioma cell cultures

International Nuclear Information System (INIS)

Gerlach, B.; Harder, A.H.; Slotman, B.J.; Sminia, P.; Hulsebos, T.J.M.; Leenstra, S.; Peter Vandertop, W.; Hartmann, K.A.

2002-01-01

Aim: Determination of in-vitro radiosensitivity and genetic alterations of cell cultures derived from human glioma biopsy tissue and established glioma cell lines. Material and Methods: Fresh brain tumor specimens of six patients were processed to early passage cell cultures. In addition the cell lines D 384 and Gli 6 were used. Cell cultures were irradiated with doses from 2 to 10 Gy. Following irradiation, cell survival was determined by clonogenic assay and survival curves were generated. The surviving fractions after 2 Gy (SF2) and 4 Gy (SF4) were used as radiosensitivity parameters. Genetic analysis included determination of the mutational and loss of heterozygosity (LOH) status of TP 53 (exons 5-8), the LOH 10- and epidermal growth factor receptor gene (EGFR) amplification status. Results: The SF2 and SF4 values ranged from 0.54 to 0.88 (mean: 0.70) and from 0.13 to 0.52 (mean: 0.32), respectively. Genetic alterations were found in the Gli 6 cell line and in two primary cell cultures. The genetic profile of Gli 6 showed LOH but no TP 53 mutation, complete LOH 10 and no EGFR amplification. The VU 15 cell culture showed TP 53 mutation but no LOH 10 or EGFR amplification, while VU 24 showed incomplete LOH 10, EGFR amplification and no TP 53 mutation. In the other four cell cultures and D 384 cell line no genetic alterations were diagnosed. Histopathological classification of glioblastoma multiforme and/or genetic alterations resulted in lower radiosensitivity. Conclusion: In this small series of early passage glioma cell cultures low radiosensitivity and alterations in cell regulatory genes were seen. Further testing of biological behavior in larger series of patient-derived material is ongoing. (orig.)

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

International Nuclear Information System (INIS)

Virsik-Peuckert, P.; Rave-Fraenk, M.; Schmidberger, H.

1996-01-01

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

Autophagy involved in resveratrol increased radiosensitivity in glioma stem cells

International Nuclear Information System (INIS)

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

2012-01-01

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

Hypoxic cell radiosensitization by moderate hyperthermia and glucose deprivation

International Nuclear Information System (INIS)

Kim, J.H.; Kim, S.H.; Hahn, E.W.

1983-01-01

Cell culture studies were carried out to determine whether moderate hyperthermia reduces the oxygen enhancement ratio of cells under well-defined cultural conditions. Using asynchronously growing HeLa cells, the OER of cells with and without glucose was determined following exposure of cells to moderate hyperthermia, 40.5omicronC for 1 hr, immediately after X irradiation. The OER of cells with 5 mM glucose was 3.2, whereas the OER of glucose-deprived cells was reduced to 2.0. The pH of the cell culture medium was kept at 7.4 throughtout the experiments. The present finding may provide a clue toward further enhancing the radiosensitization of hypoxic cells by heat

Hypoxic cell radiosensitization by moderate hyperthermia and glucose deprivation

International Nuclear Information System (INIS)

Kim, J.H.; Kim, S.H.; Hahn, E.W.

1983-01-01

Cell culture studies were carried out to determine whether moderate hyperthermia reduces the oxygen enhancement ratio of cells under well-defined cultural conditions. Using asynchronously growing HeLa cells, the OER of cells with and without glucose was determined following exposure of cells to moderate hyperthermia, 40.5 degrees C for 1 hr, immediately after X irradiation. The OER of cells with 5 mM glucose was 3.2, whereas the OER of glucose-deprived cells was reduced to 2.0. The pH of the cell culture medium was kept at 7.4 throughout the experiments. The present finding may provide a clue toward further enhancing the radiosensitization of hypoxic cells by heat

ATM-induced radiosensitization in vitro and in vivo

International Nuclear Information System (INIS)

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

2003-01-01

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

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

International Nuclear Information System (INIS)

Roberts, P.B.; Anderson, R.F.; Wilson, W.R.

1987-01-01

NC (1-nitroacridine nitracine) radiosensitization was evaluated in CHO cultures at 4 0 C. 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.)

Radiosensitization of human prostate cell line LNCAP by [6]- gingerol

International Nuclear Information System (INIS)

Silva, Josias Paulino Leal; Bellini, Maria Helena

2017-01-01

Full text: Introduction: Prostate cancer is the second most prevalent malignancy and second leading cause of cancer-related deaths among men in the world. Several different diagnostic and therapeutic approaches have been developed in order to decrease the death rates. A number of experimental and clinical studies have showed antiproliferative, pro-apoptotic, anti-metastatic and anti-angiogenic effects of several phytochemicals. [6]-Gingerol (1-[4'-hydroxy-3'-methoxyphenyl]-5-hydroxy-3- decanone), the major pungent principle of ginger, has anti-oxidant, anti-inflammation and antitumor promoting activities. Aim: The purpose of this study was to evaluate the radiosensitizing activity of [6]-Gingerol in the human prostate cancer cells. Methods: The viability was assessed (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) tetrazolium (MTS) assay. The prostate human cells (LNCAP) (2,5×103 cells/well) were seeded into 96-well plates, after 24 hr they were treated with 150 and 300μg/mL of [6]-Gingerol or vehicle alone (0.1% DMSO) in serum containing media. After incubation, MTS solution was added to the plate at a final concentration of 0.5 mg/mL. The cells were incubated for 2 hr in dark at 37. The resulting MTS-products were determined by measuring the absorbance at 490 nm with ELISA reader. In the clonogenic cell survival assay, the cells were divided into two groups: A) control, B) treated with [6]-Gingerol, C) irradiated control and D) treated with [6]-Gingerol and irradiated. The cells were irradiated by 60Co source in the range from 0 to 15 Gy, using the GammaCell 220 - Irradiation Unit of Canadian-Atomic Energy Commision Ltd. (CTR-IPEN). After 10-14 days of culture in normoxia conditions, cell colonies were fixed and stained with methanol 20% and crystal violet 0.5% and counted. Multiple comparisons were assessed by One-way ANOVA followed by Bonferroni´s tests with GraphPad Prism version 6.0 software. p< 0.05 was considered statistically

Radiosensitization of human prostate cell line LNCAP by [6]- gingerol

Energy Technology Data Exchange (ETDEWEB)

Silva, Josias Paulino Leal; Bellini, Maria Helena [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil)

2017-07-01

Full text: Introduction: Prostate cancer is the second most prevalent malignancy and second leading cause of cancer-related deaths among men in the world. Several different diagnostic and therapeutic approaches have been developed in order to decrease the death rates. A number of experimental and clinical studies have showed antiproliferative, pro-apoptotic, anti-metastatic and anti-angiogenic effects of several phytochemicals. [6]-Gingerol (1-[4'-hydroxy-3'-methoxyphenyl]-5-hydroxy-3- decanone), the major pungent principle of ginger, has anti-oxidant, anti-inflammation and antitumor promoting activities. Aim: The purpose of this study was to evaluate the radiosensitizing activity of [6]-Gingerol in the human prostate cancer cells. Methods: The viability was assessed (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) tetrazolium (MTS) assay. The prostate human cells (LNCAP) (2,5×103 cells/well) were seeded into 96-well plates, after 24 hr they were treated with 150 and 300μg/mL of [6]-Gingerol or vehicle alone (0.1% DMSO) in serum containing media. After incubation, MTS solution was added to the plate at a final concentration of 0.5 mg/mL. The cells were incubated for 2 hr in dark at 37. The resulting MTS-products were determined by measuring the absorbance at 490 nm with ELISA reader. In the clonogenic cell survival assay, the cells were divided into two groups: A) control, B) treated with [6]-Gingerol, C) irradiated control and D) treated with [6]-Gingerol and irradiated. The cells were irradiated by 60Co source in the range from 0 to 15 Gy, using the GammaCell 220 - Irradiation Unit of Canadian-Atomic Energy Commision Ltd. (CTR-IPEN). After 10-14 days of culture in normoxia conditions, cell colonies were fixed and stained with methanol 20% and crystal violet 0.5% and counted. Multiple comparisons were assessed by One-way ANOVA followed by Bonferroni´s tests with GraphPad Prism version 6.0 software. p< 0.05 was considered statistically

Different radiosensitivities of mast-cell precursors in the bone marrow and skin of mice

International Nuclear Information System (INIS)

Kitamura, Y.; Yokoyama, M.; Sonoda, T.; Mori, K.J.

1983-01-01

Although tissue mast cells are derived from the bone marrow, some descendants of bone marrow-derived precursors retain the ability to proliferate and differentiate into mast cells even after localization in the skin. The purpose of the present study was to determine the D 0 values for mast-cell precursors in the bone marrow and those localized in the skin. Bone marrow cells were removed from (WB X C57BL/6)F 1 +/+ mice after various doses of irradiation and injected into the skin of the congenic W/W/sup v/ mice which were genetically without mast cells. Radiosensitivity of mast-cell precursors in the bone marrow was evaluated by determining the proportion of the injection sites at which mast cells did not appear. For the assay of the radiosensitivity of mast-cell precursors localized in the skin, pieces of skin were removed from beige C57BL/6 (bg/sup J//bg/sup J/, Chediak-Higashi syndrome) mice after various doses of irradiation and grafted onto the backs of the normal C57BL/6 mice. Radiosensitivity of mast-cell precursors in the skin was evaluated by determining the decrease of beige-type mast cells which possessed giant granules. Mast-cell precursors in the bone marrow were much more radiosenitive than those localized in the skin. D 0 value was about 100 rad for the former and about 800 rad for the latter

Isolation and characterization of a radiosensitive Chinese hamster ovary cell line

International Nuclear Information System (INIS)

Fuller, L.F.

1987-01-01

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

Paraquat-induced radiosensitization of mammalian cells

International Nuclear Information System (INIS)

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

1983-06-01

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

Radiosensitivity of mouse germ cells

International Nuclear Information System (INIS)

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

1991-01-01

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

Radiosensitivity of Hela cells in various O2 concentrations and consideration of oxygen effect in radiotherapy

International Nuclear Information System (INIS)

Kuroda, Yoshikazu; Nyunoya, Koichiro

1979-01-01

The aim of this paper is the study of the radiosensitivity of HeLa cells in vitro in various oxygen concentrations and the consideration of the utilization of oxygen effect in radiation therapy, based on the data of HeLa cells and tumor oxygen tension. Survival curves of HeLa cells are found to be exponential as a function of radiation dose and the radiosensitivity is dependent on oxygen tension of culture medium. Relative radiosensitivity decreases remarkably at low level of oxygen, especially under 9 mmHg pO 2 . The utilization of oxygen effect in radiation may be useful in hyperbaric oxygen inhalation and not useful under local tissue hypoxia induced by tourniquet application. Reoxygenation occurs with shrinkage of tumor after irradiation and this phenomenon will diminish the value of hyperbaric oxygen in radiation therapy. (author)

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

International Nuclear Information System (INIS)

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

2011-01-01

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

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.)

Individual differences in the radiosensitivity of hematopoietic progenitor cells detected in steady-state human peripheral blood

International Nuclear Information System (INIS)

Oriya, Asami; Takahashi, Kenji; Kashiwakura, Ikuo; Inanami, Osamu; Kuwabara, Mikinori; Miura, Toshiaki; Abe, Yoshinao

2008-01-01

The aim of this study is to evaluate the individual differences in radiosensitivity of lineage-committed myeloid hematopoietic progenitors, colony-forming cells (CFC), detected in steady-state human peripheral blood (PB). Mononuclear cells were prepared from the buffy-coat of 30 individuals PB, and were assayed for CFC by semi-solid culture supplemented with cytokines. X irradiation was performed in the range of 0.5-4 Gy at a dose rate of about 80 cGy/min. The mean number of hematopoietic progenitor cells is 5866±3408 in 1 ml of buffy-coat, suggesting that the erythroid progenitor cells are the major population. The total CFC radiosensitivity parameter D 0 and n value are 1.18±0.24 and 1.89±0.98, respectively. Using a linear regression analysis, a statistically significant correlation is observed between the D 0 value and the surviving fraction at 4 Gy (r=0.611 p 0 parameter and the level of antioxidants, plasma uric acid, plasma bilirubin, and intracellular glutathione. The present study demonstrates that there are large individual differences in the radiosensitivity of hematopoietic progenitor cells as detected in steady-state human PB. These differences demonstrate almost no correlation with plasma or intracellular antioxidants. The prediction of individual differences in radiosensitivity of CFC can only be measured by 4 Gy irradiation. (author)

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-09-09

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

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

International Nuclear Information System (INIS)

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

2016-01-01

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

The merits of DNA content and cell kinetic parameters for the assessment of intrinsic cellular radiosensitivity to photon and high-LET neutron irradiation

International Nuclear Information System (INIS)

Theron, C.S.; Serafin, A.; Bohm, L.; Slabbert, J.P.

1997-01-01

Differences of the intrinsic cellular radiosensitivity between tumours make the selection of patients for specific radiation schedules very difficult. The reasons for these variations are still unclear, but are thought to be due to genomic and cellular characteristics. Radiosensitivities vary between cell cycle stages, with S-phase cells being most radioresistant and G2/M phase cells most radiosensitive. It is also well established that most tumour cells have an abnormal ploidy. DNA content and cellular proliferation kinetics therefore could influence the intrinsic radiosensitivity. This prompted us to assess the merits of these parameters as predictors of radiation response. (authors)

5-Fluorouracil modulation of radiosensitivity in cultured human carcinoma cells

International Nuclear Information System (INIS)

Smalley, S.R.; Kimler, B.F.; Evans, R.G.

1991-01-01

We evaluated conventional pulse exposure versus continuous exposure models of 5-fluorouracil (5-FU) radiosensitization in HT-29 (human colon adenocarcinoma) and DU-145 (human prostate cancer adenocarcinoma) cell lines. Cell survival following treatment with drug and/or radiation was determined by colony formation assays. Radiation was delivered either by itself, approximately midway through a 1-hr exposure to 5-FU (10 micrograms/ml), or at various times following initiation of exposure to 5-FU (0.5 microgram/ml) present throughout the entire period of incubation. Drug concentrations were selected to approximate those achieved in vivo in humans. HT-29 cells showed a plating efficiency of 87% and similar cytotoxicity (survival reduced to 0.57-0.71) for all 5-FU conditions. The Do's of the radiation survival curves were not different for 1 hr of 5-FU exposure versus radiation alone. However, continuous exposure conditions demonstrated statistically significantly different Do's from radiation alone and pulse 5-FU exposure. DU-145 cells displayed a plating efficiency of 17% and cytotoxicities of 0.10-0.91 for the 5-FU conditions. DU-145 cells showed different radiation 5-FU interactions: 5-FU produced statistically significant changes in Do well as the differences between cell lines insofar as their radiosensitization by 5-FU underscore the caution required in extrapolating these radiobiologic models to the clinical setting

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

International Nuclear Information System (INIS)

Chu Liping; Liu Qiang; Wang Qin; Li Jin; Yue Jingyin; Mu Chuanjie; Fan Feiyue

2008-01-01

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, HepG 2 , 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 HepG 2 and EC-9706 was higher than that of MCF-7. The ratio of mtDNA 4977 bp deletion of HepG 2 and EC-9706 was higher significantly than that of MCF-7 (P 2 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)

Radiosensitizers and the oxygen effects in mammalian cells

International Nuclear Information System (INIS)

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

1979-01-01

The survival curves for Chinese Hamster cells irradiated under various oxygen tensions have been determined. The variation in OER with oxygen concentration shows two distinct components. Between 1.4 and 7.0 μM the OER is constant with a value of 1.9. Experiments with nitroaromatic radiosensitizers in combination with low concentrations of oxygen show that they can all mimic the 'low concentration' oxygen effect. Of the compounds tested only misonidazole can apparently mimic the 'high concentration' oxygen effect although the full OER cannot be obtained with the authors cell line because of toxicity by the sensitizer. (Auth.)

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

Science.gov (United States)

Rahman, Wan Nordiana; Corde, Stéphanie; Yagi, Naoto; Abdul Aziz, Siti Aishah; Annabell, Nathan; Geso, Moshi

2014-01-01

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 3.47. The dose enhancement factor obtained at other energy levels followed the same direction as the theoretical calculations based on the ratio of the mass energy absorption coefficients of gold and water. This experimental evidence shows that the radiosensitization effect of gold nanoparticles varies with photon energy as predicted from theoretical calculations. However, prediction based on theoretical assumptions is sometimes difficult due to the complexity of biological systems, so further study at the cellular level is required to fully characterize the effects

Chemosensitivity and radiosensitivity testing of freshly explanted human tumour cells in vitro

International Nuclear Information System (INIS)

Wells, J.

1977-10-01

In this thesis, in vitro testing for the chemosensitivity and radiosensitivity of freshly explanted human tumour cells is described. The cells were incubated with anti-tumour drugs and either a 6-day growth test performed or a clonal growth test as a measure of survival of cell reproductive capacity. It was shown that if one aims to develop a suitable in vitro method for predicting the subsequent response of human tumour cells in situ to cytotoxic chemotherapy, the test procedure must be initiated before the explanted cells have undergone significant growth in vitro. The survival of the reproductive capacity of tumour cell explants following X-radiation was also studied. Using a 'feeder' layer technique, values for the survival curve parameter Dsub(q) were in the range 400-610 rad and the values for D 0 were in the range 120-160 rad. The shape of the X-ray survival curves did not change when cells were retested after repeated subculturing in vitro. Therefore, unlike chemosensitivity measured by the same biological end-point, radiosensitivity apparently does not change once cells have reached their maximum growth potential. (UK)

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

International Nuclear Information System (INIS)

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

2013-01-01

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

Radiosensitivity of a monoclonal human lung adenocarcinoma cell line with MDR phenotype induced by CDDP: an in vitro study

International Nuclear Information System (INIS)

Zhang Junxiang; Kong Zhaolu; Shen Zhifen; Tong Shungao; Jin Yizun

2006-01-01

The study was to evaluate radiosensitivity of a monoclonal human lung adenocarcinoma cell line SPC-A-1/CDDP-4 with MDR phenotype induced by cisplatin (CDDP) compared with its parental cell SPC-A-1 in vitro. The glutathione (GSH) content and the radiosensitivity of SPC-A-1/CDDP-4 and SPC-A-1 cells were investigated in aerobic and under hypoxia, respectively. The radiosensitization effect of buthionine sulfoximine (BSO), an inhibitor of glutathione (GSH) synthesis, to SPC-A-1/CDDP-4 and SPC-A-1 cells was observed. The results indicated that the monoclonal human lung adenocarcinoma cell line SPC-A-1/CDDP-4 showed, to some extent, a cross-resistance to 137 Cs γ-ray, in addition to its resistance to anticancer drugs (CDDP, ADM, MTX and VCR). The GSH content of SPC-A-1/CDDP-4 cells was higher than that of SPC-A-1 cells both in aerobic and under hypoxia which might account for it. BSO had radiosensitization effect to SPC-A-1/CDDP-4 and SPC-A-1 cells both in aerobic and under hypoxia, but it was stronger under hypoxia than in aerobic and it was stronger to SPC-A-1/CDDP-4 cells than to SPC-A-1 cells. (authors)

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

International Nuclear Information System (INIS)

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

2010-01-01

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

KIH-802: 2-nitroimidazole-1-acetohydroxamate as a hypoxic cell radiosensitizer

International Nuclear Information System (INIS)

Hori, H.; Murayama, C.; Mori, T.; Shibamoto, Y.; Abe, M.; Onoyama, Y.; Inayama, S.

1989-01-01

We have identified potassium 2-nitroimidazole-1-acetohydroxamate (KIH-802) as a hypoxic cell radiosensitizer potentially superior to Miso. The water-soluble acetohydroxamates of 2-nitroimidazole (KIH-802; free acid 801) and 4-nitroimidazole (KIH-852) were designed, synthesized, and evaluated by in vitro and in vivo screening against EMT6 cells. Enhancement ratios of KIH-802 and 801 were 1.92 and 1.68, respectively, compared with 1.58 for MISO all at 1 mM. These acetohydroxamates are also expected to be more effective in vitro than SR-2508 based on our previous experiments. In vivo ERs of KIH-802, 801, and 852 were 1.75, 1.50, and 1.35, respectively, compared with 1.57 for MISO all at the same dose of 200 mg/kg. The data clearly show that the addition of an acetohydroxamic acid moiety to the 2-nitroimidazole skeleton can enhance radiosensitizing ability

Potential in a single cancer cell to produce heterogeneous morphology, radiosensitivity and gene expression

International Nuclear Information System (INIS)

Ban, Sadayuki; Ishikawa, Ken-ichi; Kawai, Seiko; Koyama-Saegusa, Kumiko; Ishikawa, Atsuko; Imai, Takashi; Shimada, Yutaka; Inazawa, Johji

2005-01-01

Morphologically heterogeneous colonies were formed from a cultured cell line (KYSE70) established from one human esophageal carcinoma tissue. Two subclones were separated from a single clone (clone 13) of KYSE70 cells. One subclone (clone 13-3G) formed mainly mounding colonies and the other (clone 13-6G) formed flat, diffusive colonies. X-irradiation stimulated the cells to dedifferentiate from the mounding state to the flat, diffusive state. Clone 13-6G cells were more radiosensitive than the other 3 cell lines. Clustering analysis for gene expression level by oligonucleotide microarray demonstrated that in the radiosensitive clone 13-6G cells, expression of genes involved in cell adhesion was upregulated, but genes involved in the response to DNA damage stimulus were downregulated. The data demonstrated that a single cancer cell had the potential to produce progeny heterogeneous in terms of morphology, radiation sensitivity and gene expression, and irradiation enhanced the dedifferentiation of cancer cells. (author)

In vitro radiosensitivity of six human cell lines. A comparative study with different statistical models

International Nuclear Information System (INIS)

Fertil, B.; Deschavanne, P.J.; Lachet, B.; Malaise, E.P.

1980-01-01

The intrinsic radiosensitivity of human cell lines (five tumor and one nontransformed fibroblastic) was studied in vitro. The survival curves were fitted by the single-hit multitarget, the two-hit multitarget, the single-hit multitarget with initial slope, and the quadratic models. The accuracy of the experimental results permitted evaluation of the various fittings. Both a statistical test (comparison of variances left unexplained by the four models) and a biological consideration (check for independence of the fitted parameters vis-a-vis the portion of the survival curve in question) were carried out. The quadratic model came out best with each of them. It described the low-dose effects satisfactorily, revealing a single-hit lethal component. This finding and the fact that the six survival curves displayed a continuous curvature ruled out the adoption of the target models as well as the widely used linear regression. As calculated by the quadratic model, the parameters of the six cell lines lead to the following conclusions: (a) the intrinsic radiosensitivity varies greatly among the different cell lines; (b) the interpretation of the fibroblast survival curve is not basically different from that of the tumor cell lines; and (c) the radiosensitivity of these human cell lines is comparable to that of other mammalian cell lines

Hyperthermic radiosensitization of synchronous Chinese hamster cells: relationship between lethality and chromosomal aberrations

International Nuclear Information System (INIS)

Dewey, W.C.; Sapareto, S.A.; Betten, D.A.

1978-01-01

Synchronous Chinese hamster cells in vitro were obtained by mitotic selection. The cells were heated at 45.5 0 C for 4 min in mitosis, 11 min in G 1 , or 7 min in S sphase and then x-irradiated immediately thereafter. Colony survival from heat alone was 0.30 to 0.45, and the frequency of chromosomal aberrations induced by heat was 0.00, 0.14, or 0.97 for heat treatments during M, G 1 , or S, respectively. As shown previously, lethality from hyperthermia alone is due to chromosomal aberrations only when the cells are heated during S phase. The log survival (D 0 /sup approximately/ = 80 rad) and aberration frequency curves for cells irradiated during mitosis were linear, and the only effect of hyperthermia was to shift the curves in accord with the effect from heat alone. Thus, hyperthermia did not radiosensitize the mitotic cells. The cells irradiated in G 1 were more resistant (D 0 /sup approximately/ = 100 rad) than those irradiated in mitosis, and the survival and aberration frequency curves both had shoulders. The primary effect of hyperthermia was to greatly reduce the shoulders of the curves and to increase the slopes by about 23%. The cells irradiated in S were the most resistant (D 0 /sup approximately/ = 140 rad), and the survival and aberration frequency curves both had large shoulders. For both end points of lethality and chromosomal aberrations, heat selectively radiosensitized S-phase cells relative to G 1 cells by removing most of the shoulder and increasing the slope by about 45%. For cells treated in G 1 or S, the increase in radiosensitization following hyperthermia can be accounted for by an increase in the frequency of chromosomal aberrations

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

International Nuclear Information System (INIS)

Caputo, A.

1974-01-01

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

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

International Nuclear Information System (INIS)

Zhang Chunzhi; Kang Chunsheng; Cao Yongzhen; Pu Peiyu; Lu Zhonghong; Du Yue

2009-01-01

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)

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

International Nuclear Information System (INIS)

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

2005-01-01

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

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

Directory of Open Access Journals (Sweden)

Gang Xu

2017-01-01

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

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)

Hehlgans, Stephanie; Lange, Inga; Eke, Iris; Cordes, Nils

2009-01-01

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.

Hereditary syndromes with enhanced radiosensitivity

International Nuclear Information System (INIS)

Lohmann, D.

2000-01-01

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

The inherited basis of human radiosensitivity

International Nuclear Information System (INIS)

Gatti, R.A.

2001-01-01

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

The effects of BSO on GSH contents and radiosensitivity of retinoblastoma cells

International Nuclear Information System (INIS)

Yi Xanjin; Ding Li; Jin Yizun; Ni Chuo; Wang Wenji; Yi Yuzhen

1995-01-01

The radiobiological effects of thiol modifier BSO on retinoblastoma were studied using cultured retinoblastoma cell lines Y-79 and So-Rb 50 and retinoblastoma bearing nude mouse. The preliminary results showed that BSO can deplete intracellular GSH contents of retinoblastoma cells in vitro and vivo. In vitro data demonstrated that low and nontoxic concentration BSO increased the retinoblastoma cells radiosensitivity especially under the hypoxic condition

Knockdown of AMPKα decreases ATM expression and increases radiosensitivity under hypoxia and nutrient starvation in an SV40-transformed human fibroblast cell line, LM217.

Science.gov (United States)

Murata, Yasuhiko; Hashimoto, Takuma; Urushihara, Yusuke; Shiga, Soichiro; Takeda, Kazuya; Jingu, Keiichi; Hosoi, Yoshio

2018-01-22

Presence of unperfused regions containing cells under hypoxia and nutrient starvation contributes to radioresistance in solid human tumors. It is well known that hypoxia causes cellular radioresistance, but little is known about the effects of nutrient starvation on radiosensitivity. We have reported that nutrient starvation induced decrease of mTORC1 activity and decrease of radiosensitivity in an SV40-transformed human fibroblast cell line, LM217, and that nutrient starvation induced increase of mTORC1 activity and increase of radiosensitivity in human liver cancer cell lines, HepG2 and HuH6 (Murata et al., BBRC 2015). Knockdown of mTOR using small interfering RNA (siRNA) for mTOR suppressed radiosensitivity under nutrient starvation alone in HepG2 cells, which suggests that mTORC1 pathway regulates radiosensitivity under nutrient starvation alone. In the present study, effects of hypoxia and nutrient starvation on radiosensitivity were investigated using the same cell lines. LM217 and HepG2 cells were used to examine the effects of hypoxia and nutrient starvation on cellular radiosensitivity, mTORC1 pathway including AMPK, ATM, and HIF-1α, which are known as regulators of mTORC1 activity, and glycogen storage, which is induced by HIF-1 and HIF-2 under hypoxia and promotes cell survival. Under hypoxia and nutrient starvation, AMPK activity and ATM expression were increased in LM217 cells and decreased in HepG2 cells compared with AMPK activity under nutrient starvation alone or ATM expression under hypoxia alone. Under hypoxia and nutrient starvation, radiosensitivity was decreased in LM217 cells and increased in HepG2 cells compared with radiosensitivity under hypoxia alone. Under hypoxia and nutrient starvation, knockdown of AMPK decreased ATM activity and increased radiation sensitivity in LM217 cells. In both cell lines, mTORC1 activity was decreased under hypoxia and nutrient starvation. Under hypoxia alone, knockdown of mTOR slightly increased ATM

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

International Nuclear Information System (INIS)

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

2016-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-12-15

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

Evaluation of nitrobenzimidazoles as hypoxic cell radiosensitizers

International Nuclear Information System (INIS)

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

1983-01-01

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

Evaluation of nitrobenzimidazoles as hypoxic cell radiosensitizers

International Nuclear Information System (INIS)

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

1983-01-01

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

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

International Nuclear Information System (INIS)

Lawrence, Theodore S.; Chang, Emily Y.; Hahn, Tina M.; Hertel, Larry W.; Shewach, Donna S.

1996-01-01

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

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

International Nuclear Information System (INIS)

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

1997-01-01

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

In vitro radiosensitization by oxaliplatin and 5-fluorouracil in a human colon cancer cell line

International Nuclear Information System (INIS)

Kjellstroem, Johan; Kjellen, Elisabeth; Johnsson, Anders

2005-01-01

The current study was designed to compare the radiosensitizing effects of oxaliplatin and 5-fluorouracil (5FU) in a human colon cancer cell line. A human colon cancer cell line (S1) was treated with various doses of oxaliplatin, 5FU, radiation, and combinations thereof. Various clinically used schedules were mimicked. 5FU was either incubated during 1 h ('bolus') or 24 h ('continuous infusion'). When combining oxaliplatin and 5FU, an isobologram analysis revealed synergistic effects, regardless of 5FU schedule. The IC 10 and IC 50 -doses for the drugs where then combined with radiotherapy. With equitoxic drug doses (IC 50 ), radiosensitization was observed in the following order: oxaliplatin>5FU 24 h>5FU 1 h exposure. The degree of potentiation corresponded to approximately 0.8 Gy, 0.7 Gy, and 0.2 Gy, respectively. In this experimental setting, oxaliplatin seemed to be a better radiosensitizer than 5FU, and longer incubation time with 5FU was better than short exposure

Radiosensitivity and TP 53, EGFR amplification and LOH10 analysis of primary glioma cell cultures

NARCIS (Netherlands)

Gerlach, Bärbel; Harder, Anna H.; Hulsebos, Theo J. M.; Leenstra, Sieger; Slotman, Berend J.; Vandertop, W. Peter; Hartmann, Karl-Axel; Sminia, Peter

2002-01-01

Aim: Determination of in-vitro radiosensitivity and genetic alterations of cell cultures derived from human glioma biopsy tissue and established glioma cell lines. Material and Methods: Fresh brain tumor specimens of six patients were processed to early passage cell cultures. In addition the cell

Correlation between the parameters of radiosensitivity in human cancer cell lines

International Nuclear Information System (INIS)

Park, Woo Yoon; Kim, Won Dong; Min, Kyung Soo

1998-01-01

We conducted clonogenic assay using human cancer cell lines (MKN-45, PC-14, Y-79, HeLa) to investigate a correlation between the parameters of radiosensitivity. Human cancer cell lines were irradiated with single doses of 1, 2, 3, 5, 7 and 10Gy for the study of radiosensitivity and sublethal damage repair capacity was assessed with two fractions of 5Gy separated with a time interval of 0, 1, 2, 3, 4, 6 and 24 hours. Surviving fraction was assessed with clonogenic assay using Sperman-Karber method and mathematical analysis of survival curves was done with linear-quadratic (LQ), multitarget-single hit(MS) model and mean inactivation dose(D). Surviving fractions at 2Gy(SF2) were variable among the cell lines, ranged from 0.174 to 0.85. The SF2 of Y-79 was lowest and that of PC-14 was highest(p<0.05, t-test). LQ model analysis showed that the values of α for Y-79, MKN-45, HeLa and PC-14 were 0.603, 0.356, 0.275 and 0.102 respectively, and those of β were 0.005, 0.016, 0.025 and 0.027 respectively. Fitting to MS model showed that the values of Do for Y-79, MKN-45, HeLa and PC-14 were 1.59, 1.84, 1.88 and 2.52 respectively, and those of n were 0.97, 1.46, 1.52 and 1.69 respectively. The Ds calculated by Gauss-Laguerre method were 1.62, 2.37, 2.61 and 3.95 respectively. So the SF2 was significantly correlated with α, Do and D. Their Pearson correlation coefficiencics were -0.953 and 0.993, 0.999 respectively(p<0.05). Sublethal damage repair was saturated around 4 hours and recovery ratios (RR) at plateau phase ranged from 2 to 3.79. But RR was not correlated with SF2, α, β, Do, D. The intrinsic radiosensitivity was very different among the tested human cell lines. Y-79 was the most sensitive and PC-14 was the least sensitive. SF2 was well correlated with α, Do, and D. RR was high for MKN-45 and HeLa but had nothing to do with radiosensitivity parameters. These basic parameters can be used as baseline data for various in vitro radiobiological experiments

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

International Nuclear Information System (INIS)

Guo Xinwei; Lu Xueguan; Tong Liumei; Zong Tianzhou; Chen Liesong

2011-01-01

Objective: To investigate the radiosensitive effect of hypoxia-inducible factor 1α (HIF-1α) inhibitor YC-1 on hypoxic glioma SHG44 cell line and its related mechanism. Methods: Glioma SHG44 cell line was cultured in normoxic (20% O 2 ), continuous hypoxia (1% O 2 ) for 12 h and 24 h, continuous hypoxia plus YC-1 was performed for 12 h and 24 h, respectively. The expression of HIF-1α was assessed by Western blot. The radiosensitivity was evaluated by the survival curve, and the sublethal damage repair (SLDR) ability was measured by dose-fraction experiment. Results: HIF-1α protein levels of glioma SHG44 cells were significantly increased after hypoxic cultures for 12 h and 24 h than those of the corresponding cells cultured in normoxic, while the radiosensitivity was lower. The OER (oxygen-enhancement ratio) of SHG44 cells in hypoxia for 12 h and 24 h were 1.22 and 1.37, respectively. By the further statistical analysis it was found that SLDR ability of glioma SHG44 was increased at hypoxia, and when irradiation was carried one at the interval of 8, 10, 12 h it was statistically significant (P<0.05). HIF-1α protein levels of glioma SHG44 cells cultured in hypoxia plus YC-1 for 12 h and 24 h were decreased significantly compared to the corresponding cells cultured in hypoxia only, while the radiosensitivity was significantly increased. the EF (enhancement factor) of YC-1 for glioma SHG44 cells at hypoxia for 12 h and 24 h was 1.27. By the further statistical analysis it was also found that SLDR ability was decreased significantly for hypoxic SHG44 cells which was co-cultured with YC-1, and at the interval of 8, 10, 12 h irradiation was statistically significant (P<0.05). Conclusion: YC-1 can increase the radiosensitivity of hypoxic glioma SHG44 cell line, and its mechanism is related to SLDR inhibited by YC-1. (authors)

The inherited basis of human radiosensitivity

Energy Technology Data Exchange (ETDEWEB)

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

2001-11-01

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

The potential value of the neutral comet assay and the expression of genes associated with DNA damage in assessing the radiosensitivity of tumor cells.

Science.gov (United States)

Jayakumar, Sundarraj; Bhilwade, Hari N; Pandey, Badri N; Sandur, Santosh K; Chaubey, Ramesh C

2012-10-09

The assessment of tumor radiosensitivity would be particularly useful in optimizing the radiation dose during radiotherapy. Therefore, the degree of correlation between radiation-induced DNA damage, as measured by the alkaline and the neutral comet assays, and the clonogenic survival of different human tumor cells was studied. Further, tumor radiosensitivity was compared with the expression of genes associated with the cellular response to radiation damage. Five different human tumor cell lines were chosen and the radiosensitivity of these cells was established by clonogenic assay. Alkaline and neutral comet assays were performed in γ-irradiated cells (2-8Gy; either acute or fractionated). Quantitative PCR was performed to evaluate the expression of DNA damage response genes in control and irradiated cells. The relative radiosensitivity of the cell lines assessed by the extent of DNA damage (neutral comet assay) immediately after irradiation (4Gy or 6Gy) was in agreement with radiosensitivity pattern obtained by the clonogenic assay. The survival fraction of irradiated cells showed a better correlation with the magnitude of DNA damage measured by the neutral comet assay (r=-0.9; Pcomet assay (r=-0.73; Pcomet assay was better than alkaline comet assay for assessment of radiosensitivities of tumor cells after acute or fractionated doses of irradiation. © 2012 Elsevier B.V. All rights reserved.

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

International Nuclear Information System (INIS)

Liu Shuhua

1992-01-01

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

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

Characteristics of fluorinated nitroazoles as hypoxic cell radiosensitizers

International Nuclear Information System (INIS)

Shibamoto, Y.; Nishimoto, S.; Shimokawa, K.

1989-01-01

Types of 2-nitroimidazoles and 3-nitro-1,2,4-triazoles bearing one or two fluorine atoms on their side chains were synthesized to evaluate their physicochemical properties, radiosensitizing effects, and toxicity. The reduction potential of the compounds containing one fluorine was similar to that of misonidazole (MISO), whereas that of the difluorinated compounds was slightly higher. Both mono- and difluorinated compounds had an in vitro sensitizing activity comparable to or slightly higher than that of MISO. The fluorinated 3-nitrotriazoles were almost as efficient as the 2-nitroimidazoles with the same substituent. In vivo, some of the compounds were up to twice more efficient than MISO, whereas others were as efficient as MISO. Toxicity in terms of LD50/7 in mice was quite variable depending on the side-chain structure; the amide derivatives were less toxic than MISO, whereas the alcohol and ether derivatives were more toxic. In view of the radiosensitizing effect and toxicity in vivo, at least one compound, KU-2285 (a 2-nitroimidazole with an N1-substituent of: CH2CF2CONHCH2CH2OH) has been found to be as useful a hypoxic cell sensitizer as SR-2508

A preliminary investigation into the extent of increased radioresistance or hyper-radiosensitivity in cells of hamster cell lines known to be deficient in DNA repair

International Nuclear Information System (INIS)

Skov, K.; Marples, B.; Matthews, J.B.; Zhou, H.; Joiner, M.C.

1994-01-01

The response to low doses of X rays was assessed in cells of three hamster cell lines which are defective in DNA repair and was compared with their parental lines. Cells of the V79-derived double-strand break repair-deficient line XR-V15B showed no radioresistance in the 0.5-Gy range compared with the V79B wild type, but instead showed an exponential response. Cells of the single-strand break repair-deficient line EM9 showed hyper-radiosensitivity and exhibited increased radioresistance. Most interestingly, cells of the UV-20 cell line appeared to respond exponentially, as a continuation of the hyper-radiosensitive portion of the curve, with no evidence of increased radioresistance. This line is defective in an incision step of excision repair and is sensitive to crosslinking agents. Further studies are warranted to address the possible role of single- and double-strand break repair and excision repair in hyper-radiosensitivity and increased radioresistance. 24 refs., 4 figs

EGFR inhibitor C225 increases the radiosensitivity of human lung squamous cancer cells

Directory of Open Access Journals (Sweden)

Yang Ruijie

2010-10-01

Full Text Available Abstract Background The purpose of the present study is to investigate the direct biological effects of the epidermal growth factor receptor (EGFR inhibitor C225 on the radiosensitivity of human lung squamous cancer cell-H520. H520 cells were treated with different dosage of 60Co γ ray irradiation (1.953 Gy/min in the presence or absence of C225. The cellular proliferation, colony forming capacity, apoptosis, the cell cycle distribution as well as caspase-3 were analyzed in vitro. Results We found that C225 treatment significantly increased radiosensitivity of H-520 cells to irradiation, and led to cell cycle arrest in G1 phase, whereas 60Co γ ray irradiation mainly caused G2 phase arrest. H-520 cells thus displayed both the G1 and G2 phase arrest upon treatment with C225 in combination with 60Co γ ray irradiation. Moreover, C225 treatment significantly increased the apoptosis percentage of H-520 cells (13.91% ± 1.88% compared with the control group (5.75% ± 0.64%, P Conclusion In this regard, C225 treatment may make H-520 cells more sensitive to irradiation through the enhancement of caspase-3 mediated tumor cell apoptosis and cell cycle arrest.

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

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

2012-01-01

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

Evaluation of a MTT assay in measurement of radiosensitizing effect

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

1999-01-01

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

Exogenous wild type p53 gene affects radiosensitivity of human lung adenocarcinoma cell line under hypoxia

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Wang Jianhua; Wang Feng; Liu Yongping; Zhang Yaping; Ni Yan; Li Shirong

2008-01-01

Objective: To evaluate the effect of exogenous wild type p53 (wtp53) gene on radiosensitivity of human lung adenocarcinoma cell line under hypoxia. Methods: Human lung adenocarcinoma cell line A549 was transfected with adenovirus carrying recombinant exogenous wtp53. Four irradiation groups were studied: normal cell (Group A), wtp53 transfected cell (Group B), normal cell under hypoxia (Group C) and wtp53 transfected cell under hypoxia(Group D). Cells were irradiated with 9 MeV electron beams. Cellular survival fraction was analyzed. Multi-target single-hit model was used to plot the survival curve. D 0 , D q , oxygen enhancement ratio (OER), sensitizing enhancement ratio (SER) and other parameters were used to evaluate the effects of wtp53 gene on radiosensitivity of A549. The cell apoptotic rate of each group was examined by flow cytometry. Results: OER was 1.75 and 0.81 before and after wtp53 transfection. SER was 1.77 in oxic circumstance and 3.84 under hypoxia. The cell apoptotic rate of Group A and B was lower than Group C and D (F=7.92, P=0.048), with Group A lower than B and Group C lower than D (F=82.50, P=0.001). But Group B and D were similar(t=2.04, P=0.111). Conclusions: Hypoxia can increase the radiation resistance of lung adenocarcinoma cell line A549. The wtp53 can promote apoptosis and improve tumor radiosensitivity, especially under hypoxia. (authors)

Radiobiological properties of radiosensitive XR-1 Chinese hamster cells and hybrids from these and human A-T cells

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Bahari, I.B.

1989-01-01

Results indicate that XR-1 cells were very radiosensitive to gamma-irradiation compared to its parental type, and that this radiosensitivity is cell cycle dependent. Irradiating the cells the G 1 or plateau phase did not induce any delay entering S-phase but mitotic delays were observed in both XR-1 and the wild-type cells. The delays per unit dose were much longer for XR-1. A delay in subculture from plateau phase reduced the mitotic delay in both cell lines. Unlike the wild-type cells which expressed virtually all chromosome-type aberrations after irradiation of G 1 cells, the XR-1 cells expressed both chromatid- as well as chromosome-type aberrations. There was a one-to-one correlation between total aberrations induced and lethality for both cells. Many of these radiobiological properties of XR-1 cells relative to the wild-type cells, mimic the response of A-T cells relative to the normal human cells. However, the restoration of radioresistance and cytogenetic response in the XR1/AT5BI(4) hybrid cells suggest that the XR-1 and A-T cells have different defects because of the complementation in the hybrids. It also appears that this genetic defect is recessive in nature

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

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Mohamed, H.M.S.

2009-01-01

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

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

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Noaman, E.; Sayed, H.M.; Medhat, A.M.; Morcos, N.Y.S.

2010-01-01

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

Radiosensitivity evaluation of Human tumor cell lines by detecting 4977bp deletion in mitochondrial DNA

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Zhang Yipei

2009-01-01

Objective: To explore the feasibility of determining radiosensitivity of human tumor cell lines in vitro using the assay of mtDNA4977bp deletion. Methods: Three human tumor cell lines were selected in this study, HepG 2 , EC-9706 and MCF-7. The surviving fraction(SF), the ratio of mtDNA4977bp deletion and DNA damage were detected by MTT assay and nested PCR technique respectively. Results: MTT assay: The SF of HepG 2 and EC-9706 after irradiated by 2, 4and 8Gy was lower significantly than that of MCF-7, which showed that the radiosensitivity of HepG 2 and EC-9706 was higher than that of MCF-7. But there was no statistical difference of SF between HepG 2 and EC-9706. PCR method:The differences on mtDNA 4977bp deletion in mitochondrial DNA among HepG 2 , EC-9706 and MCF-7 were not significant after 1Gy and 4Gy γ-ray irradiation. The ratio of 4977bp deletion in mitochondrial DNA of HepG 2 and EC-9706 increased while that of MCF-7 decreased after 8Gy irradiation. The ratio of mtDNA 4977bp deletion of HepG 2 and EC-9706 was higher significantly than that of MCF-7, which implies that the radiosensitivity of HepG 2 and EC-9706 was higher than that of MCF -7. Conclusion: As a new biological marker, mtDNA4977bp deletion may be hopeful to evaluate the radiosensitivity of tumor cells more objectively and exactly. (authors)

The small molecule inhibitor QLT0267 Radiosensitizes squamous cell carcinoma cells of the head and neck.

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Iris Eke

Full Text Available BACKGROUND: The constant increase of cancer cell resistance to radio- and chemotherapy hampers improvement of patient survival and requires novel targeting approaches. Integrin-Linked Kinase (ILK has been postulated as potent druggable cancer target. On the basis of our previous findings clearly showing that ILK transduces antisurvival signals in cells exposed to ionizing radiation, this study evaluated the impact of the small molecule inhibitor QLT0267, reported as putative ILK inhibitor, on the cellular radiation survival response of human head and neck squamous cell carcinoma cells (hHNSCC. METHODOLOGY/PRINCIPAL FINDINGS: Parental FaDu cells and FaDu cells stably transfected with a constitutively active ILK mutant (FaDu-IH or empty vectors, UTSCC45 cells, ILK(floxed/floxed(fl/fl and ILK(-/- mouse fibroblasts were used. Cells grew either two-dimensionally (2D on or three-dimensionally (3D in laminin-rich extracellular matrix. Cells were treated with QLT0267 alone or in combination with irradiation (X-rays, 0-6 Gy single dose. ILK knockdown was achieved by small interfering RNA transfection. ILK kinase activity, clonogenic survival, number of residual DNA double strand breaks (rDSB; gammaH2AX/53BP1 foci assay, cell cycle distribution, protein expression and phosphorylation (e.g. Akt, p44/42 mitogen-activated protein kinase (MAPK were measured. Data on ILK kinase activity and phosphorylation of Akt and p44/42 MAPK revealed a broad inhibitory spectrum of QLT0267 without specificity for ILK. QLT0267 significantly reduced basal cell survival and enhanced the radiosensitivity of FaDu and UTSCC45 cells in a time- and concentration-dependent manner. QLT0267 exerted differential, cell culture model-dependent effects with regard to radiogenic rDSB and accumulation of cells in the G2 cell cycle phase. Relative to corresponding controls, FaDu-IH and ILK(fl/fl fibroblasts showed enhanced radiosensitivity, which failed to be antagonized by QLT0267. A

DNA-radiosensitivity and repair in mammolian cells

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

1979-01-01

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

Preliminary screening of the radiosensitivity-associated genes on colorectal cancer

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Xing Chungen; Yang Xiaodong; Zhou Liying; Wu Yongyou; Jiang Yinfen; Dai Hong; Lv Xiaodong; Gong Wei

2007-01-01

The screening of radiosensitive genes of human colorectal cancer was made by gene chip. Two human colorectal cancer cell lines LOVO and SW480 were cultivated and the total RNA was extracted from at least lxl0 7 cells. Then the gene expression profiling was performed by HG-U133 Plus 2.0 Array and the difference of gene expression has been analyzed. The results shows that there are 16882 genes expressed in LOVO cell and 17114 genes expressed in SW480 cell through gene expression profiling. It has been found that the genes with 2-fold expressed differentially include 908 genes up-regulated and 1312 genes down-regulated. The same genes, such as Fas and NFkB which is up-regulated, Caspas6, and RAD21 which is down-regulated, have been proved to be related to radiosensitivity. The genes with high expression level including CEACAM5, THBS1, SERPINE2, ARL7, HPGD in LOVO cell may also be related to the radiosensitivity. And the genes with high expression level including SCD, NQ01, LYZ, KRT20, ATP1B1 in SW480 cell may be related to the radioresistance of human colorectal cancer. It could be concluded that the radiosensitivity of colorectal cancer can be reflected from gene and protein expression level. And gene expression profiling is a fast and sensitive tool to predict the radiosensitivity and screen radiosensitive genes of colorectal cancer. (authors)

EGFR and its mutant EGFRvIII as modulators of tumor cell radiosensitivity

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Lammering, G.; Hewit, T.H.; Contessa, J.N.; Hawkins, W.; Lin, P.S.; Valerie, K.; Mikkelsen, R.; Dent, P.; Schmidt-Ullrich, R.K.

2001-01-01

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

Release from the Crabtree effect by hypoxic cell radiosensitizers

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Mustea, I.; Bara, A.

1979-01-01

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

Review of our histological criteria for the radiosensitivity of uterine cervical cancer

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Tsukahara, Yoshiharu; Shiozawa, Kyuyo; Tsukamoto, Takashi; Sonehara, Morio; Noguchi, Hiroshi

1975-01-01

The determination of radiosensitiveness based on 111 operated specimens after test irradiation of 1000R was compared with that based on 64 specimens which had received biopsies seven days after irradiation. It was concluded that the determination of radiosensitiveness by local biopsy could be applied to practical use. The results of this study are listed as follows: (1) Radiosensitivity exists within tumor cells themselves before irradiation, while radiosensitiveness is a complicated change in which some reaction on the host side added to degenerated tumor cells. (2) In the determination of radio-sensitiveness, there was a good accordance of 85% between biopsies and removed specimens. (3) The followings are findings of favorable radiosensitiveness based on the removed specimens; (a) neutrocyte infiltration within cancer nests, (b) lysis of cancer nests, (c) destruction of fundus of cancer nests, (d) damages of advanced sites of cancer infiltration, (e) damages of chromatin. As unfavorable findings, (f) mitosis, (g) abundant viable cells. (4) Various histological findings within cancer nests and variation of radiosensitiveness according to various regions of the tumor often cause a discord with biopsies. (5) Many specimens which show the intermediate histological type in maturation before irradiation indicate favorable radiosensitiveness. Even if they belong to the intermediate type, the specimens in which the issued histological findings are mixed show mostly unfavorable radiosensitiveness. (6) Removed specimens can be expressed in indices of radiosensitiveness. (Ichikawa, K.)

Potential predictive assay using RAR-β for radiosensitization by 13-cis-retinoic acid and interferonα2a in human carcinoma cells

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Ryu, Samuel; Nevaldine, Barbara H.; Unguraneau, Carmen; Chung, Chung T.; King, Gerald A.; Stein, Joseph P.

1997-01-01

Purpose: Cell culture studies have shown increased cytotoxicity and inhibition of cell proliferation by combined use of 13-cis-retinoic acid (CRA) and interferon-α2a (IFN). Clinically, a direct antitumor activity has been observed by combined use of CRA and IFN in patients with cancer of the cervix and skin. Since IFN is known to enhance radiation response in selected human carcinoma cell lines, we carried out a series of experiments in an effort to improve the efficacy of radiation therapy by CRA and IFN in combination. Materials and Methods: Human cervical carcinoma ME-180 and HeLa cell lines were exposed to 10 μM CRA and 1000 unit/ml IFN in combination for 48 hours prior to radiation. Endpoint of radiosensitization study was colony-forming ability of single cells. Retinoic acid receptors (RAR and RXR) were detected by RNAse protection assay. Apoptosis was quantitated by using immunohistochemical staining method (Apop Tag). The cells were also transfected with bcl-2 or RAR-β gene to explore the mechanism of radiation-induced cell killing. Results: A substantial radiosensitization was observed by the combined use of CRA and IFN in human cervical carcinoma ME-180 cells in culture. The radiation enhancement ratio was 2.0 at 1% cell survival level. The principal mode of radiation-induced cell killing was apoptosis since more than 90% of the ME-180 cells showed evidence of apoptosis by combined treatment of CRA, IFN, and radiation. Both apoptosis and radiosensitization were blocked by transfecting bcl-2 gene into ME-180 cells. In contrast to these results with ME-180 cells, no radiosensitization was observed in HeLa cells by CRA and IFN under the same experimental conditions. Both cell lines express various RXR and RAR mRNAs. However, the RAR-β was undetectable in HeLa cells but present at high levels in ME-180 cells, as determined by RNAse protection assay. Because of this differential expression of RAR-β mRNA, we hypothesized that RAR-β may mediate the

Investigations of the radiosensitivity of enzymes of the NAD metabolism localized in the cell nucleus in the spleen of white mice

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Beisel, P.

1975-01-01

The radiosensitivity of enzymes of the NAD metabolism localized in the cell nuclei and of NAD glycohydrolase in the total homogenate of the spleen of white mice was investigated. At the same time the DNA and protein contents were determined. After whole-body irradiation with 510 R, the activity of NAD pyrophosphorylase and NAD glycohydrolase located in the cell nuclei is markedly lower as early as 3 hours after irradiation; this decrease is noticeable until the 10th day after irradiation. With regard to the dose dependence of the radiosensitivity at 6 and 24 hours after irradiation, it was found that NAD pyrophosphorylase and the NAD glycohydrolase localized in the cell nuclei were very radiosensitive even at doses [de

The merits of cell kinetic parameters for the assessment of intrinsic cellular radiosensitivity to photon and high linear energy transfer neutron irradiation

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Theron, Therina; Slabbert, Jacobus; Serafin, Antonio; Boehm, Lothar

1997-01-01

Purpose: Differences in tumor response and intrinsic cellular radiosensitivity make the selection of patients for specific radiation modalities very difficult. The reasons for these differences are still unclear, but are thought to be due to genomic and cellular characteristics. Because radiosensitivities vary between cell cycle stages and because S phase cells are very radioresistant, cell cycle kinetic parameters could be a candidate for predicting intrinsic radiosensitivity. Methods and Materials: A panel of 15 tumor cell lines was analyzed for S phase content and potential doubling times (T pot ), and the influence of these parameters on the intrinsic radiosensitivity to 60 Coγ- and p(66)/Be neutron irradiation was assessed. Results: S phase content and T pot show a statistically significant correlation with the mean inactivation dose for photons. The correlation between cell kinetic parameters and the mean inactivation dose for neutrons showed the same trend as photon sensitivity but this was not found to be statistically significant. Conclusions: S phase content and T pot were identified as suitable criteria for predicting photon sensitivity. It is suggested that cell kinetic parameters could play a role in identifying neutron sensitive tumors if both tumor and normal cells are analyzed

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

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

2008-01-01

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

The combination of olaparib and camptothecin for effective radiosensitization

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

2012-01-01

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

Correlation of RAD51 and radiosensitization of methotrexate

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

2012-01-01

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

Effect of radiosensitizer BSO on the incidence of micronuclei in cultured cells

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Jin Yizun; Cai Rongmei; Ding Li; Shen Zhifen; Xu Liming; Yang Jiakuan

1992-01-01

The effects of BSO, a potent radiosensitizing and chemical sensitizing chemical, on the incidence of micronuclei in four different cell lines have been studied using the cytokinesis-block (CB) method. The number of micronuclei in cultured human peripheral lymphocytes, Chinese hamster cells and human breast cancer cells were not affected by 0.1-2 mmol/L BSO treatment alone. However, significant increase in the incidence of micronuclei in these cells could be detected when BSO was used in combination with γ-irradiation. Linear relationship between the incidence of micronuclei and the radiation dose was observed

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

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Chen, Susie; Wang Hongyan; Ng, Wooi Loon; Curran, Walter J.; Wang Ya

2011-01-01

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.

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

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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.

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

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Bache, Matthias; Taubert, Helge; Vordermark, Dirk; Zschornak, Martin P; Passin, Sarina; Keßler, Jacqueline; Wichmann, Henri; Kappler, Matthias; Paschke, Reinhard; Kaluđerović, Goran N; Kommera, Harish

2011-01-01

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 (IC 50 ) 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

Catecholamines of the body tissues and radiosensitivity of rodents

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

1975-01-01

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

Modulation of clonogenicity, growth, and radiosensitivity of three human epidermoid tumor cell lines by a fibroblastic environment

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Gery, Bernard; Little, John B.; Coppey, Jacques

1996-01-01

Purpose: To develop a model vitro system to examine the influence of fibroblasts on the growth and survival of human tumor cells after exposure to ionizing radiation. Methods and Materials: The cell system consists of three epidermoid carcinoma cell lines derived from head and neck tumors having differing growth potentials and intrinsic radiosensitivities, as well as a low passage skin fibroblast strain from a normal human donor. The tumor cells were seeded for five days prior to exposure to radiation: (a) in the presence of different numbers of fibroblasts, (b) in conditioned medium from stationary fibroblast cultures, and (c) on an extracted fibroblastic matrix. Results: When grown with fibroblasts, all three tumor cell lines showed increased clonogenicity and increased radioresistance. The radioprotective effect was maximal at a density of approximately 10 5 fibroblasts/100 mm Petri dish, and was greatest in the intrinsically radiosensitive tumor cell line. On the other hand, the effects of incubation with conditioned medium or on a fibroblastic matrix varied among the tumor cell lines. Thus, the protective effect afforded by coculture with fibroblasts must involve several cellular factors related to the fibroblast itself. Conclusions: These observations emphasize the importance of cultural conditions on the apparent radiosensitivity of human tumor cell lines, and suggest that the fibroblastic connective tissue enveloping the malignant cells should be considered when the aim is to establish a radiopredictive assay from surgical tumors fragments

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

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Dikomey, Ekkehard

2012-01-01

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

Radiosensitizing effect of epothilone B on human epithelial cancer cells

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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.)

Intrinsic radiosensitivity and PLD repair in osteosarcoma cell lines

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Sugimoto, M.; Toguchida, J.; Kotoura, Y.; Yamamuro, T.; Utsumi, H.

1992-01-01

The response to radiation of seven osteosarcoma cell lines was analysed by in vitro colony-forming assay and compared with that of eight human fibroblast strains. The values of D 0 , the surviving fraction after 2 Gy (S2Gy), and the mean inactivation dose (D-bar) of osteosarcoma cells in log-phase culture were significantly higher than those of fibroblast strains (p<0.01). PLD (potentially lethal damage) repair of osteosarcoma cells evaluated in the plateau phase of growth showed great variation for enhancement of survival, although all of the values were maximised within 12 h after irradiation. In the osteosarcoma, intrinsic radiosensitivity in vitro reflected the clinical response to radiation. However, the capacity for PLD repair might not be a good indicator for predicting the results of radiation therapy. (author)

Catecholamines of the body tissues and radiosensitivity of rodents

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

1975-01-01

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

Studies on Drosophila radiosensitivity strains

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

1985-01-01

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

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

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Wenbo Wang

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

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

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

2004-01-01

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

Fulvestrant radiosensitizes human estrogen receptor-positive breast cancer cells

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Wang, Jing; Yang, Qifeng; Haffty, Bruce G.; Li, Xiaoyan; Moran, Meena S.

2013-01-01

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

Radiosensitization effect by combination with paclitaxel in vivo, including the effect on intratumor quiescent cells

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Masunaga, Shin-ichiro; Ono, Koji; Suzuki, Minoru; Nishimura, Yasumasa; Kinashi, Yuko; Takagaki, Masao; Hori, Hitoshi; Nagasawa, Hideko; Uto, Yoshihiro; Tsuchiya, Izumi; Sadahiro, Sotaro; Murayama, Chieko

2001-01-01

Purpose: To evaluate the radiosensitization effect on solid tumors upon combination treatment with paclitaxel (TXL), including the effect on intratumor quiescent (Q) cells. Methods and Materials: Mice bearing SCC VII or EL4 solid tumors received 5-bromo-2'-deoxyuridine (BrdU) continuously for 5 days to label all proliferating (P) cells. The mice then received γ-irradiation with or without tirapazamine (TPZ) at various time points after TXL administration. Another group of mice received a series of test doses of γ-rays while alive or after tumor clamping to obtain hypoxic fractions (HFs) in the tumors at various time points after TXL administration. Immediately after irradiation, the tumor cells were isolated and incubated with a cytokinesis blocker. The micronucleus (MN) frequency in cells without BrdU labeling (Q cells) was determined using immunofluorescence staining for BrdU. Meanwhile, 6 h after irradiation, the tumor cells were isolated from the solid tumors in another group of mice, and the apoptosis frequency in Q cells was also determined with immunofluorescence staining for BrdU. The MN and apoptosis frequency in total (P+Q) tumor cells were determined from the tumors that were not pretreated with BrdU. For the measurement of the HFs, the MN or apoptosis frequency of Q cells was then used to calculate the surviving fraction of Q cells from the regression line for the relationship between the MN or apoptosis frequency and the surviving fraction of total tumor cells. Results: In both SCC VII and EL4 tumors, maximum values of mitotic index (MI) and apoptosis frequency were observed 9 and 24 h after TXL administration, respectively. However, on the whole, the apoptosis frequency for SCC VII was very low. γ-Irradiation 9 h after TXL administration induced significant radiosensitization effects on the total cells of both tumors. Irradiation at 60 h had a more significant effect on total cells of EL4 tumor, but no significant effect on total cells of SCC VII

Cyclin D1 overexpression, cell cycle progression and radiosensitivity in MBP cells

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Wu Lijun; Yu Zengliang

2000-11-01

Clones that exhibited a minimum of 7-8 fold cyclin D1 level above the parent cell lines or the vector control were obtained after transfected with the entire coding sequence of human 1.1 kb cyclin D1 cDNA. Studies showed that there was no significant difference in Radiosensitivity between over-expressing cyclin D1 and control cultures from either mouse or human origin. Using flow cytometry to access cell cycle distribution in the exponentially growth cultures of MCF10F-D1-21 and MCF10F-V-3, it was found that there was a 50 percent increase in the proportion of G2/M phase cells and 5.3 percent decrease in the proportion of G0/G1 phase cells in MCF10F-D1-21 comparing with MCF10F-V-3, though they were with the same proportion of cells in S phase

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

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Zhao Baofeng; Tian Mei; Lei Hongwei; Su Xu

2006-01-01

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

Radiosensitivity of cultured insect cells: I. Lepidoptera

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Koval, T.M.

1983-01-01

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

The combination of olaparib and camptothecin for effective radiosensitization

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Miura Katsutoshi

2012-04-01

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

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

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Ji Xiaoqin; Ji Jiang; Chen Yongbing; Shan Fang; Lu Xueguan

2014-01-01

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 A 549 and H 1299 cells, and the effects of CAF on the radiosensitivity of A 549 and H 1299 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 A 549 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 H 1299 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 (SF 2 ) of A 549 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 SF 2 of H 1299 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 A 549 cells and H 1299 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)

Tumour-specific radiosensitizers for radiation therapy

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Denekamp, J.

1977-01-01

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

EphA2 modulates radiosensitive of hepatocellular carcinoma cells via p38/mitogen-activated protein kinase-mediated signal pathways

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Qiao Jin

2015-10-01

Full Text Available This experiment was conducted to investigate the role of EPH receptor A2 (EphA2 in the modulation of radiosensitivity of hepatic cellular cancer (HCC cells and to determine whether p38/mitogen-activated protein kinase (p38MAPK signaling mediated EphA2 function in this respect. The protein expressions of EphA2 and phosphorylated p38MAPK were tested in HCC and normal hepatic tissues. In HCC 97H cells, EphA2 was overexpressed and knocked out by transfection with EphA2 expression vector and EphA2-ShRNA, respectively, prior to cell exposure to low-dose irradiation. Significantly upregulated EphA2 and phosphorylated p38MAPK were observed in HCC tissues, compared with those in normal hepatic tissues. Low-dose irradiation (1 Gy only caused minor damage to HCC 97H cells, as assessed by alterations in cell viability, apoptosis rate, and cell healing capacity (p = 0.072, p = 0.078, and p = 0.069 respectively. However, EphA2 knock-out in HCC 97H cells induced significant reduction in cell viability and cell healing capacity after these cells were subjected to low-dose irradiation. Apoptosis rate underwent dramatic increase (p < 0.01. By contrast, EphA2 overexpression in HCC 97H cells reversed these effects and enhanced cell colony formation rate, thus displaying remarkable attenuation of radiosensitivity of HCC 97H cells. Further, SB203580, a specific inhibitor of p38MAPK, was added to HCC 97H cells over-expressing EphA2. The effect of EphA2 overexpression on the radiosensitivity of HCC 97H cells was abrogated. Thus, the present study indicates that EphA2 have the ability to negatively regulate the radiosensitivity of HCC 97H cells, which mainly depends on 38MAPK-mediated signal pathways.

Radiosensitivity of soft tissue sarcomas

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

1989-01-01

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

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

Science.gov (United States)

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

2018-05-16

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

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

International Nuclear Information System (INIS)

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

1994-01-01

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

Changes in radiosensitivity of V-79 cells accompanying growth and cell division

International Nuclear Information System (INIS)

Lehnert, S.

1975-01-01

The X-ray survival curve for asynchronous Chinese hamster V-79 cells at 17 to 20 hr after plating when cells are irradiated as microclones of two to four cells differs from the survival curve seen at short times after plating, when single cells are irradiated, in having higher D 0 (300 rad vs 160 rad) and negligible extrapolation number. As a consequence of the difference in D 0 the difference in survival between single cells and clones increases with increasing dose. Transient cyclic changes in survival occur at early times after plating and are probably related to partial synchronization induced by trypsinization. In addition there is a progressive increase in survival which develops with increasing time after plating, as the number of cells in the clones increases. Decrease in radiosensitivity with increasing number of cells irradiated is also observed for synchronous cells when cells at corresponding points in the cell cycle are irradiated. Accumulation and repair of sublethal damage is demonstrable in cells irradiated at short times after plating, but cannot be shown at 20 hr after plating when cells are irradiated as microclones. (U.S.)

Modern concepts for basic radiobiological factors characterizing tumor tissue radiosensitivity

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Gocheva, L.; Sergieva, K.

2002-01-01

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

Trypsinization and the radiosensitivity of mitotic and log phase Chinese hamster V79 cells exposed to 250 kVp X-rays

International Nuclear Information System (INIS)

Reddy, N.M.S.; Stevenson, A.F.G.; Lange, C.S.

1989-01-01

The authors studied the influence of trypsin-induced morphological changes on the x-radiosensitivity of cells plated at either low (4-600/cm 2 ) or high (2 x 10 4 /cm 2 ) density and grown overnight before treatments. Trypsin treatment induced contraction and rounding of spread cells. The results suggest that: (1) trypsin-induced cell contraction affects the ability of cells to repair radiation damage, (2) spread cells are better able to repair potential lethal damage (PLD) than rounded cells, (3) immediate plating survival of cells in high-density cultures may not represent their intrinsic radiosensitivity and (4) cell-to-cell contact is not necessary for log phase cells to repair PLD. (author)

Re-evaluation of in vitro radiosensitivity of human fibroblasts of different genetic origins

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Deschavanne, P.J.; Debieu, D.; Malaise, E.P.; Fertil, B.

1986-08-01

Statistical analysis of the radiosensitivity of 204 survival curves of non-transformed human fibroblast cell strains of different genetic origins was made using the multi-target one-hit model (characterized by parameters eta and D/sub 0/), the surviving fraction for a 2 Gy dose (S/sub 2/) and the mean inactivation dose (D-bar). D-bar is found to be the parameter for characterization of anomalous radiosensitivity linked to a genetic disorder and discrimination between groups of cell strains of differing radiosensitivity. It allows the description of a range of 'normal' radiosensitivity for control fibroblasts and classification of genetic disorders as a function of their mean radiosensitivity expressed in terms of D-bar. Nine groups of cell strains appear to exhibit radiosensitivity differing significantly from the controls: seven groups are hypersensitive (ataxia-telengiectasia homozygotes and heterozygotes, Cockayne's syndrome, Gardner's syndrome, 5-oxoprolinuria homozygotes and heterozygotes, Fanconi's anaemia) and two groups are more radioresistant (fibroblasts from retinoblastoma patients and individuals with chromosome 13 anomalies). Since the coupled parameter eta and D/sub 0/ failed to discriminate between the radiosensitivity of the different genetic groups, the use of D-bar to make an intercomparison of intrinsic radiosensitivity of non-transformed human fibroblasts is recommended. (U.K.).

Re-evaluation of in vitro radiosensitivity of human fibroblasts of different genetic origins

International Nuclear Information System (INIS)

Deschavanne, P.J.; Debieu, D.; Malaise, E.P.; Fertil, B.

1986-01-01

Statistical analysis of the radiosensitivity of 204 survival curves of non-transformed human fibroblast cell strains of different genetic origins was made using the multi-target one-hit model (characterized by parameters eta and D 0 ), the surviving fraction for a 2 Gy dose (S 2 ) and the mean inactivation dose (D-bar). D-bar is found to be the parameter for characterization of anomalous radiosensitivity linked to a genetic disorder and discrimination between groups of cell strains of differing radiosensitivity. It allows the description of a range of 'normal' radiosensitivity for control fibroblasts and classification of genetic disorders as a function of their mean radiosensitivity expressed in terms of D-bar. Nine groups of cell strains appear to exhibit radiosensitivity differing significantly from the controls: seven groups are hypersensitive (ataxia-telengiectasia homozygotes and heterozygotes, Cockayne's syndrome, Gardner's syndrome, 5-oxoprolinuria homozygotes and heterozygotes, Fanconi's anaemia) and two groups are more radioresistant (fibroblasts from retinoblastoma patients and individuals with chromosome 13 anomalies). Since the coupled parameter eta and D 0 failed to discriminate between the radiosensitivity of the different genetic groups, the use of D-bar to make an intercomparison of intrinsic radiosensitivity of non-transformed human fibroblasts is recommended. (U.K.)

Membrane specific drugs as radiosensitizers

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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)

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

International Nuclear Information System (INIS)

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

1985-01-01

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

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

International Nuclear Information System (INIS)

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

2012-01-01

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

The yield of DNA double strand breaks determined after exclusion of those forming from heat-labile lesions predicts tumor cell radiosensitivity to killing.

Science.gov (United States)

Cheng, Yanlei; Li, Fanghua; Mladenov, Emil; Iliakis, George

2015-09-01

The radiosensitivity to killing of tumor cells and in-field normal tissue are key determinants of radiotherapy response. In vitro radiosensitivity of tumor- and normal-tissue-derived cells often predicts radiation response, but high determination cost in time and resources compromise utility as routine response-predictor. Efforts to use induction or repair of DNA double-strand-breaks (DSBs) as surrogate-predictors of cell radiosensitivity to killing have met with limited success. Here, we re-visit this issue encouraged by our recent observations that ionizing radiation (IR) induces not only promptly-forming DSBs (prDSBs), but also DSBs developing after irradiation from the conversion to breaks of thermally-labile sugar-lesions (tlDSBs). We employ pulsed-field gel-electrophoresis and flow-cytometry protocols to measure total DSBs (tDSB=prDSB+tlDSBs) and prDSBs, as well as γH2AX and parameters of chromatin structure. We report a fully unexpected and in many ways unprecedented correlation between yield of prDSBs and radiosensitivity to killing in a battery of ten tumor cell lines that is not matched by yields of tDSBs or γH2AX, and cannot be explained by simple parameters of chromatin structure. We propose the introduction of prDSBs-yield as a novel and powerful surrogate-predictor of cell radiosensitivity to killing with potential for clinical application. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

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

Science.gov (United States)

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

2014-01-01

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

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

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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.

Expression of p210 BCR/ABl increases hematopoietic progenitor cell radiosensitivity

International Nuclear Information System (INIS)

Santucci, M.A.; Anklesaria, P.; Das, I.J.; Sakakeeny, M.A.; FitzGerald, T.J.; Greenberger, J.S.; Laneuville, P.

1993-01-01

The cytogenetic finding of the Ph1+ chromosome and its molecular biologic marker bcr/abl gene rearrangement in cells from patients with chronic myeloid leukemia are associated with a proliferative advantage of the Ph1+ clone in vivo. Although the transition to the acute terminal phase or blastic crisis is often associated with additional cytogenetic abnormalities, the molecular events which correlate the initial cytogenetic lesion with the terminal phase are poorly understood. Defective cellular DNA repair capacity is often associated with chromosomal instability, increased mutation frequency, and biologic alterations. The authors tested whether the protein product of the bcr/abl translocation (p210) could alter DNA repair after gamma-irradiation of murine cell lines expressing the bcr/abl cDNA. The 32D cl 3 parent, 32D cl 3 pYN (containing the control vector plasmid) and each of two sources of 32D cl 3 cells expressing p210 cDNA (32D-PC1 cell line and 32D-LG7 subclone) showed a D 0 of 1.62, 1.57, 1.16, and 1.27 Gy, respectively. Thus, expression of the p210 product induced a significant increase in radiosensitivity at the clinically relevant radiation therapy dose-rate. The increased radiosensitivity of p210-expressing cells persisted if cells were held before plating in a density-inhibited state for 8 hr after gamma-irradiation, indicating little effect on the repair of potentially lethal gamma-irradiation damage. The IL-3 dependent parent 32D cl 3 cells demonstrated programmed cell death in the absence of growth factor or following gamma-irradiation to 200 cGy. Expression of p210 cDNA in the 32D-PC1 and 32D-LG7 subclones abrogated IL-3 requirement of these cell lines and inhibited gamma-irradiation induced programmed cell death. These data suggest a role for p210 in amplifying gamma-irradiation DNA damage or broadly inhibiting DNA repair, conditions that may stimulate further cytogenetic alterations in hematopoietic cells. 43 refs., 3 figs., 1 tab

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

Energy Technology Data Exchange (ETDEWEB)

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

1978-06-01

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

Effects of binding metronidazole to a copper-acetate compound on radiosensitizer properties

International Nuclear Information System (INIS)

Negron, Ana C. Valderrama; Silva, Denise de Oliveira; Cruz, Aurea S.

2009-01-01

Copper compounds exhibit interesting biological properties. Nitroimidazoles show radiosensitizer properties for radiotherapy tumor treatment. In the present work, the effect of binding metronidazole (1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole = MTZ) to copper-acetate on the radiosensitizer properties has been investigated. A compound of copper-acetate-MTZ was prepared and characterized. The experiments were carried out by gamma-irradiation of Hep2 (human larynx cancer) cells under hypoxic conditions. The radiation doses for 50% cell survival in the presence of radiosensitizer were about 8.2 Gy for CuAcMTZ or free MTZ. The effect of binding metronidazole to copper acetate on radiosensitizer properties is mainly related to the radiosensitizer process which involves two events for CuAcMTZ in contrast to one event observed for the MTZ free drug. (author)

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.

Effect of constitutive androstane receptor on radiosensitization of mictomycin C and its homologoue-629

International Nuclear Information System (INIS)

Zhang Jianghong; Jin Yizun

2008-01-01

The object of this work is to evaluate radiosensitization of MMC and its analogue 5-(aziridin-l-yl)-3- hydroxymethyl-1-methylindole-4,7-dione(629) and how transfection of constitutive androstane receptor (CAR) affect their biological effects. The expressions of CAR mRNA and CYP2B6 mRNA in HepG2 cells and g2car cells were detected by RT-PCR. The radiosensitization of MMC and 629 in vitro were evaluated in HepG2 cells and g2car cells by colony formation under anaerobic and aerobic condition. The effect of 629 on cell cycle and apoptosis of HepG2 cells and g2car cells were assayed by flow cytometry. It was found that plasmid mCAR1/pCR3 was transfected into g2car cells successfully and target CYP2B6 was transactivated by CAR. To compare with aerobic and anaerobic, the radiosensitization of MMC and 629 to HepG2 cells and g2car cells had significantly enhanced, the radiosensitization of 629 was stronger than its parent compound-MMC under aerobic and anaerobic condition, and transfect CAR gene could improve the radiosensitization of MMC and 629. Furthermore, CYP2B6 is one master enzyme for the metabolism of MMC and 629. Transfection of CAR can increase expression of CYP2B6 mRNA in HepG2 cells, and can affect radiosensitization of MMC and 629. (authors)

Radiosensitivity in ataxia-telangiectasia

International Nuclear Information System (INIS)

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

1998-01-01

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

Radiosensitivity in ataxia-telangiectasia

Energy Technology Data Exchange (ETDEWEB)

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

1998-12-31

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

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

International Nuclear Information System (INIS)

Hoshino, K.; Kameyama, Y.

1988-01-01

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

Radiosensitivity of higher plants

International Nuclear Information System (INIS)

Feng Zhijie

1992-11-01

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

Radiosensitivity and ras oncogene expression in preneoplastic rat tracheal epithelial cells

International Nuclear Information System (INIS)

Thomassen, D.G.; Wuensch, S.A.; Kelly, G.

1988-01-01

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)

Prediction of radiosensitivity of human tumor cell lines in vitro by determining 4977bp deletion in mitochondrial DNA

International Nuclear Information System (INIS)

Rong Qinglin; Cao Yongzhen; Zhang Yaowen; Zhao Xinran; Wang Qin; Li Jin; Liu Qiang

2008-01-01

Objective: To evaluate the possibility of predicting the radiosensitivity of tumor cell lines using the assay of the mtDNA4977bp deletion. Methods: The mtDNA4977bp deletion of HepG 2 cells and PC-3 cells were detected by nested PCR after irradiated by various doses of x-ray. Results: The radiation-induced mtDNA4977bp deletion of the tumor cell lines of HepG 2 and PC-3 were detected after irradiated. There was a dose dependent in the mtDNA4977bp deletion of two tumor cell lines. The deletion rate of HepG 2 was higher significantly than that of PC-3 at each point of radiation dose (P 2 was higher than that of PC-3. Conclusion: The assay of the mtDNA4977bp deletion may be an approach to predict the radiosensitivity of tumor cells. (authors)

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

International Nuclear Information System (INIS)

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

2015-01-01

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

The measurement of intrinsic cellular radiosensitivity in human tumours and normal tissues

International Nuclear Information System (INIS)

Lawton, P.A.

1995-01-01

Human tumour and normal cell radiosensitivity are thought to be important factors determining the response of tumour and normal tissues to radiotherapy, respectively. Clonogenic assays are the standard method for measuring radiosensitivity but they are of limited applicability for clinical use with fresh human tumours. The main aim of this work was to evaluate the Adhesive Tumour Cell Culture System (ATCCS), as a method for measuring the radiosensitivity of human tumours. A soft agar clonogenic assay, the modified Courtenay-Mills assay, was used as a standard to compare with the ATCCS. The demonstration that fibroblast contamination could occur with both assay methods led to the investigation of a new technique for removing unwanted fibroblasts from tumour cell suspensions and to the use of a multiwell assay for measuring fibroblast radiosensitivity. (author)

The measurement of intrinsic cellular radiosensitivity in human tumours and normal tissues

Energy Technology Data Exchange (ETDEWEB)

Lawton, P.A.

1995-12-31

Human tumour and normal cell radiosensitivity are thought to be important factors determining the response of tumour and normal tissues to radiotherapy, respectively. Clonogenic assays are the standard method for measuring radiosensitivity but they are of limited applicability for clinical use with fresh human tumours. The main aim of this work was to evaluate the Adhesive Tumour Cell Culture System (ATCCS), as a method for measuring the radiosensitivity of human tumours. A soft agar clonogenic assay, the modified Courtenay-Mills assay, was used as a standard to compare with the ATCCS. The demonstration that fibroblast contamination could occur with both assay methods led to the investigation of a new technique for removing unwanted fibroblasts from tumour cell suspensions and to the use of a multiwell assay for measuring fibroblast radiosensitivity. (author).

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

International Nuclear Information System (INIS)

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

2009-01-01

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

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

International Nuclear Information System (INIS)

Michelin, S.C.; Gallegos, C.E.; Dubner, D.L.; Baffa Trasci, S.; Favier, B.; Carosella, E.D.

2010-01-01

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) [es

Hematoporphyrin derivatives potentiate the radiosensitizing effects of 2-deoxy-D-glucose in cancer cells

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Dwarakanath, B.S.; Adhikari, J.S.; Jain, Viney

1999-01-01

Purpose: Two deoxy-D-glucose (2-DG), an inhibitor of glucose transport and glycolysis, has been shown to differentially inhibit the repair of radiation damage in cancer cells by reducing the flow of metabolic energy. Since hematoporphyrin derivatives (Hpd) inhibit certain enzymes of the respiratory metabolism, resulting in an increase in the glucose usage and glycolysis, Hpd could possibly enhance the energy-linked radiosensitizing effects of 2-DG in cancer cells. The purpose of the present work was to verify this suggestion. Methods and Materials: Two human tumor cell lines (cerebral glioma, BMG-1 and squamous cell carcinoma, 4197) and a murine tumor cell line (Ehrlich ascites tumor [EAT], F-15) in vitro were investigated. A commercially available preparation of Hpd, Photosan-3 (PS-3) was used in the present studies. Cells incubated with 0-10 μg/ml PS-3 for 0-24 h before irradiation were exposed to 2.5 Gy of Co-60 gamma rays and maintained under liquid holding conditions for 1-4 h to facilitate repair. 2-DG (0-5 mM) added at the time of irradiation was present during the liquid holding. Radiation-induced cytogenetic damage (micronuclei formation) and cell death (macrocolony assay) were analyzed as parameters of radiation response. Effects of these radiosensitizers on glucose usage and glycolysis were also studied by measuring the glucose consumption and lactate production using enzymatic assays. Results: The glucose consumption and lactate production of BMG-1 cells (0.83 and 1.43 pmole/cell/h) were twofold higher than in the 4197 cells (0.38 and 0.63 pmole/cell/h). Presence of PS-3 (10 μg/ml) enhanced the rate of glycolysis (glucose consumption and lactate production) in these cells by 35% to 65%, which was reduced by 20% to 40% in the presence of 5 mM 2-DG. In exponentially growing BMG-1 and EAT cells, presence of 2-DG (5 mM; equimolar with glucose) for 4 hours after irradiation increased the radiation-induced micronuclei formation and cell death by nearly 40

Radiosensitivity of spermatogenous epithelium stem cells of mice of different strains and age

International Nuclear Information System (INIS)

Konoplyannikova, O.A.; Konoplyannikov, A.G.

1988-01-01

In experiments on CBA and BALB/c male mices (3 months of age) and F 1 (CBAxC57BL/6) hybrides (at the age of 3, 12, and 24 months) a difference was noted in the radiosensitivity of spermatogenous epithelium stem cells displayed by the changes in their colony-forming ability to testicular tubules 42 days following local 60 Co-γ-irradiation. The older the hybrid mice the smaller was the number of spermatogenous epithelium stem cells

Determining and predictive factors for the tumor radiosensitivity

International Nuclear Information System (INIS)

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

2008-01-01

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

ATM-mediated Snail Serine 100 phosphorylation regulates cellular radiosensitivity

International Nuclear Information System (INIS)

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

2013-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

1984-06-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2006-07-01

Eradication of circulating hematopoietic cells has been long known to be the first noticeable somatic effect following total body ionizing radiation (IR) exposure. Among these hematopoietic cells a marked differences in sensitivity to IR have been documented reflecting the remarkable degree of heterogeneity in cell type, proliferative capacity and cell cycle status within the bone marrow cells. From all the hematopoietic cells, the small lymphocyte has the greatest radiosensitivity. In fact, a decline in absolute lymphocyte count has been used to assess IR dose in the early phase of observation after IR exposure. At moderate doses, bone marrow recovery is triggered by the differentiation of stem/early progenitor cells, which confirms further their differential sensitivity to radiation exposure. Although differences in radiosensitivity of the stem cell pool have also been documented, little is known from a molecular viewpoint. To gain insight into the molecular programs underlying the response o f hematopoietic cells to radiation exposure, we have applied a genome wide analysis strategy based on cDNA micro arrays. This technology offers a unique opportunity to dissect complex biological process by assessing three types of questions, which are, in order of complexity: Which genes are differentially expressed among the samples studied:Which genes are expressed in a coordinated manner and what are the regulators involved,what are the global biological pathways mobilized. To answer these questions transcriptional changes occurring after exposure of mice to whole body irradiation (2 Gy) were monitored in bone marrow and spleen. The time course was established in vivo and encompassed the reversible eradication of cells. For each kinetic point RNA was collected from both, spleen or sorted B.M. populations from irradiated and sham irradiated mice. The sham irradiated mice were used to eliminate stress modifications due to handling.The results highlight numerous

The molecular basis of radiosensitivity

International Nuclear Information System (INIS)

McMillan, T.J.

1989-01-01

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

Cooperative Enhancement of Radiosensitivity After Combined Treatment of 17-(Allylamino)-17-Demethoxygeldanamycin and Celecoxib in Human Lung and Colon Cancer Cell Lines

Science.gov (United States)

Kim, Young-Mee

2012-01-01

We investigated whether the combined treatment of 17-(allylamino)-17-demethoxygeldanamycin (17-AAG), an inhibitor of heat-shock protein 90 (hsp90), and celecoxib, an inhibitor of cyclooxygenase-2, can cooperatively enhance the radiosensitivity of various human cancer cells. Combined treatment with 17-AAG and celecoxib, at clinically relevant concentrations, cooperatively induced radiosensitization in all tested cancer cells, but not in normal cells. Cooperative radiosensitization by the drug combination was also shown in a human tumor xenograft system. We found that ataxia-telangiectasia and rad3-related (ATR) and ataxia-telangiectasia mutated (ATM) are novel client proteins of hsp90. Combined treatment with 17-AAG and celecoxib cooperatively induced downregulation of ATR and ATM. In conclusion, combined treatment with 17-AAG and celecoxib at clinically relevant concentrations may significantly enhance the therapeutic efficacy of ionizing radiation. PMID:21830942

Axin gene methylation status correlates with radiosensitivity of lung cancer cells

International Nuclear Information System (INIS)

Yang, Lian-He; Stoecker, Maggie; Wang, Endi; Xu, Ke; Wang, En-Hua; Han, Yang; Li, Guang; Xu, Hong-Tao; Jiang, Gui-Yang; Miao, Yuan; Zhang, Xiu-Peng; Zhao, Huan-Yu; Xu, Zheng-Fan

2013-01-01

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

Radiosensitivity of hepatocellular carcinoma

International Nuclear Information System (INIS)

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

2011-01-01

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

Response of resting L5178Y-S and L5178Y-R cells with different radiosensitivity to radiation and hydroxyurea

International Nuclear Information System (INIS)

Afanas'ev, G.G.; Shumel', I.; Valitska, M.; Nekokojchitska, Eh.; Beer, Ya. Z.; Pelevina, I.I.

1981-01-01

A study was made of cloning capacity of radiosensitive L5178YS and radioresjstant L5J78YR cells of mouse leukaemia suspension culture after X-irradiation and postradiation treatment with hydroxyurea at 37 deg and 34 deg C. It was shown that both cell lines possess a good cloning capacity at the stationary phase of growth; they are more radiosensitive than cells at the logarithmic phase of growth and cannot repair potentially lethal damages either after decreasing the temperature or the administration of h droxyurea. The postradiation treatment with hydroxyurea enhances the effect of radiation by 2 times in the case of R cells, and by 2 and 1.3 times, depending on the incubation temperature, in the case of S cells

Effects of glutathione depletion by buthionine sulfoximine on radiosensitization by oxygen and misonidazole in vitro

International Nuclear Information System (INIS)

Shrieve, D.C.; Denekamp, J.; Minchinton, A.I.

1985-01-01

Buthionine sulfoximine (BSO) has been used to deplete glutathione (GSH) in V79-379A cells in vitro, and the effect on the efficiency of oxygen and misonidazole (MISO) as radiosensitizers has been determined. Treatment with 50 or 500 μM BSO caused a rapid decline in GSH content to less than 5% of control values after 10 hr of exposure. Removal of BSO resulted in a rapid regeneration of GSH after 50 μM BSO, but little regeneration was observed over the subsequent 10-hr period after 500 μM. Cells irradiated in monolayer on glass had an oxygen enhancement ratio (OER) of 3.1. After 10-14 hr pretreatment with 50 μM BSO, washed cells were radiosensitized by GSH depletion at all oxygen tensions tested. The OER was reduced to 2.6, due to greater radiosensitization of hypoxic cells than aerated ones by GSH depletion. In similar experiments performed with MISO, an enhancement ratio of 2.0 could be achieved with 0.2 mM MISO in anoxic BSO-pretreated cells, compared to 2.7 mM MISO in non-BSO-treated cells. These apparent increases in radiosensitizer efficiency in GSH-depleted cells could be explained on the basis of radiosensitization of hypoxic cells by GSH depletion alone. These results are consistent with hypoxic cell radiosensitization by GSH depletion and by MISO or oxygen acting by separate mechanisms

Increased radiosensitivity of HPV-positive head and neck cancer cell lines due to cell cycle dysregulation and induction of apoptosis

International Nuclear Information System (INIS)

Arenz, Andrea; Ziemann, Frank; Wittig, Andrea; Preising, Stefanie; Engenhart-Cabillic, Rita; Mayer, Christina; Wagner, Steffen; Klussmann, Jens-Peter; Wittekindt, Claus; Dreffke, Kirstin

2014-01-01

Human Papillomavirus (HPV)-related head and neck squamous cell carcinoma (HNSCC) respond favourably to radiotherapy as compared to HPV-unrelated HNSCC. We investigated DNA damage response in HPV-positive and HPV-negative HNSCC cell lines aiming to identify mechanisms, which illustrate reasons for the increased sensitivity of HPV-positive cancers of the oropharynx. Radiation response including clonogenic survival, apoptosis, DNA double-strand break (DSB) repair, and cell cycle redistribution in four HPV-positive (UM-SCC-47, UM-SCC-104, 93-VU-147T, UPCI:SCC152) and four HPV-negative (UD-SCC-1, UM-SCC-6, UM-SCC-11b, UT-SCC-33) cell lines was evaluated. HPV-positive cells were more radiosensitive (mean SF2: 0.198 range: 0.22-0.18) than HPV-negative cells (mean SF2: 0.34, range: 0.45-0.27; p = 0.010). Irradiated HPV-positive cell lines progressed faster through S-phase showing a more distinct accumulation in G2/M. The abnormal cell cycle checkpoint activation was accompanied by a more pronounced increase of cell death after x-irradiation and a higher number of residual and unreleased DSBs. The enhanced responsiveness of HPV-related HNSCC to radiotherapy might be caused by a higher cellular radiosensitivity due to cell cycle dysregulation and impaired DNA DSB repair. (orig.) [de

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

International Nuclear Information System (INIS)

Chu Xuegang; Hong Chengjiao; Zhang Baoguo

2012-01-01

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

Correlation between radiosensitivity of transplanted solid tumor and nutritive condition of host animal

Energy Technology Data Exchange (ETDEWEB)

Ando, K [Showa Univ., Tokyo (Japan). School of Medicine

1975-04-01

Studies on radiosensitivity of the transplanted tumor were carried out and the following results were obtained: 1. Radiosensitivity of the tumor ran parallel to the growth rate. 2. Malnutrition of the host after irradiation made the tumor radiosensitive, probably because the sublethally damaged tumor cell did not recover. 3. Mitotic index correlated well with radiosensitivity, and the low mitotic index caused by starvation made the tumor cell recover poorly. 4. The DNA synthetic rate measured by means of iodine labeled IUdR did not successfully correlate with the mitotic rate, presumably because of the role of thymidine pool size in this experiment. 5. The serum protein level possibly with the tumor growth, which modified the radiosensitivity. 6. Serum oxygen was difficult to interpret, however, it might be compensated by erythrocytosis in a starved condition.

Radiosensitivity of continuous cultures: experiments with diploid yeast

International Nuclear Information System (INIS)

Kiefer, J.; Wagner, E.

1975-01-01

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

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

International Nuclear Information System (INIS)

Revesz, L.; Edgren, M.

1982-01-01

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

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.

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

Directory of Open Access Journals (Sweden)

Xiaomeng Zhang

2011-02-01

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

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

International Nuclear Information System (INIS)

Xia Shu; Yu Shiying

2006-01-01

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

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

International Nuclear Information System (INIS)

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

2003-01-01

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

The enhancement of radiosensitivity by celecoxib, selective cyclooxygenase-2 inhibitor, on human cancer cells expressing differential levels of cyclooxygenase-2

International Nuclear Information System (INIS)

Pyo, Hong Ryull; Shin, You Keun; Kim, Hyun Seok; Seong, Jin Sil; Suh, Chang Ok; Kim, Gwi Eon

2003-01-01

To investigate the modulation of radiosensitivity by celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, on cancer cells over- and under-expressing COX-2. A clonogenic radiation survival analysis was performed on A549 human lung and MCF-7 human breast cancer cell lines incubated in both 1 and 10% fetal bovine serum (FBS) containing media. The apoptosis in both cell lines was measured after treatment with radiation and/or celecoxib. Celecoxib enhanced the radiation sensitivity of the A549 cells in the medium containing the 10% FBS, with radiation enhancement ratios of 1.58 and 1.81 respectively, at surviving fractions of 0.1, with 30 μ M and 50 μ M celecoxib. This enhanced radiosensitivity disappeared in the medium containing the 1% FBS. Celecoxib did not change the radiation sensitivity of the MCF-7 cells in either media. The induction of apoptosis by celecoxib and radiation was not synergistic in either cell line. Celecoxib, a selective COX-2 inhibitor, preferentially enhanced the effect of radiation on COX-2 over-expressing cancer cells compared to the cells with a low expression, and this effect disappeared on incubation of the cells during drug treatment in the medium with suboptimal serum concentration. Apoptosis did not appear to be the underlying mechanism of this radiation enhancement effect due to celecoxib on the A549 cells. These findings suggest radiosensitization by a selective COX-2 inhibitor is COX-2 dependent

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

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

2017-12-01

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

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

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

2014-01-01

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

Rapid-mix studies on the anomalous radiosensitization of mammalian cells by 5-chloro-1-methyl-4-nitroimidazole

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Watts, M.E.; Hodgkiss, R.J.; Sehmi, D.S.; Woodcock, M.

1980-01-01

It has been suggested that the anomalously high radiosensitization shown by 5-chloro-1-methyl-4-nitroimidazole (CMNI) arises from dissociation of the CMNI radical-anion, yielding Cl - and an arylating free radical, and that the importance of this dehalogenation process could be investigated by irradiating hypoxic mammalian cells in vitro in the presence of CMNI, followed by the rapid addition of oxygen to prevent the dehalogenation process. 0.1 mmol dm -3 CMNI gave a sensitizer enhancement ratio (SER) of 1.7 when irradiated under steady-state conditions with 250 kVp X-rays (dose rate 3.93 Gymin -1 ) using V79 379A cells. Irradiation with 2.5 MeV electrons in the rapid-mix apparatus with 0.15 mmol dm -3 CMNI flowing through both tubes gave a slightly lower value, SER=1.5, in hypoxia. When air- or oxygen saturated 0.15 mmol dm -3 CMNI in Eagle's MEM were added to cells irradiated in hypoxic 0.15 mmol dm -3 CMNI solution 17 ms after irradiation, no change in SER was observed. Control experiments without CMNI also confirmed that the addition of oxygen at this time has no influence on radiosensitization. It was concluded that since a significant reduction in SER was not observed, the elimination of the ortho-substituted 'leaving group' is not responsible for the anomalously high radiosensitization efficiency. (U.K.)

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

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

2001-01-01

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

In vitro studies on radiosensitization effect of glucose capped gold nanoparticles in photon and ion irradiation of HeLa cells

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Kaur, Harminder; Pujari, Geetanjali; Semwal, Manoj K.; Sarma, Asitikantha; Avasthi, Devesh Kumar

2013-01-01

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

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

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Chiricuta, I.

1981-12-01

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

Interspecies variations inchromosomal radiosensitivity and repair among mammals

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Leonard, A.

1988-01-01

A review is presented of studies comparing relative chromosomal radiosensitivity of different mammalian species with the objective of assessing the induction of chromosomal aberrations in somatic cells following acute irradiation, the in vivo survival of peripheral blood lymphocytes carrying chromosomal abberations, and the correlation between chromosomal radiosensitivity of peripheral blood lymphocytes and of male germ cells. The ultimate aim was to find whether animal cell experiments can be used to replace experiments in man. The studies showed that the differences in radiosensitivity of the peripheral blood lymphocytes in the most commonly used animals and in man are insignificant and the results in animals are qualitatively and quantitatively representative of what can be expected for man. The life of peripheral blood lymphocytes carrying chromosomal abberations, however, is very short in most experimental animals. The animals thus cannot be used in studies of chromosome damage resulting from chronic irradiation. The studies also show that the yields of dicentric chromosomes in peripheral blood lymphocytes and of reciprocal translocations induced in germ cells are characteristic of each species and animal experiments cannot replace direct studies in man in this respect. (L.O.). 3 tabs., 40 refs

pSv3neo transfection and radiosensitivity of human cancer cell lines

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Parris, C.N.; Masters, J.R.W.; Green, M.H.L.

1990-01-01

Immortalisation of human fibroblasts by transfection with a plasmid, pSV3neo, results in an increase in their radioresistance. The change in radiosensitivity may either be a consequence of transformation or due to expression of the SV40 T-antigen in pSV3neo. To investigate these two possibilities, we transfected pSV3neo into cells already transformed and immortalised. The radiosensitivies of three human bladder cancer cell lines were unaltered in clones expressing T-antigen, indicating that the changes observed in fibroblasts probably are a consequence of transformation, and not the presence of SV40 T-antigen. (author)

Radiosensitivities of sensitized lymphocytes

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Taniguchi, Kazuto

1979-01-01

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

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

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

2001-01-01

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

Role and mechanism of PKC on radiosensitization in pancreatic carcinoma cell line Panc-1

International Nuclear Information System (INIS)

Qiao Qiao; Zhang Shuo; Chen Yanzhi; Li Guang

2008-01-01

Objective: To explore the effect of PKC on radiosensitization in pancreatic carcinoma cell line Panc-1, and its mediating mechanism. Methods: Panc-1 cells were treated with the specific activator of PKC (phorbol 12-myristate 13-acetate, PMA) and the specific inhibitor of PKC (chelerythrine, CH) to observe the SF2 changes. Cell survival was determined by clonogenic assay. The apoptosis rates of the cells were analyzed by flow cytometry with Annexin V/PI staining. The expression of apoptosis related protein Bcl-2 and Bax after the treatment of CH and/or irradiation was determined by immunocytochemistry. Results: The SF 2 values of radiation group, PMA group and CH group were 0.78 ± 0.02, 0.92 ± 0.11 and 0.19 ± 0.20, respectively. CH can significantly increase the sensitivity of Panc-1 to irradiation. SERs of Panc-1 cells were 1.05, 1.24 and 1.77 after the treatment of 0.5, 2 and 8 μmol/L of CH, respectively. The result of flow cytometry analysis showed that PMA decreased the apoptosis index with irradiation, while CH significantly increased the apoptosis index. Expression of Bax protein was increased significantly (P<0.05) while that of Bcl-2 was not influenced; however, the ratio of Bax/Bcl-2 was increased. Conclusions: PKC regulates the radiosensitivity of Panc-1 by mediating the apoptosis of tumor cells. (authors)

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

International Nuclear Information System (INIS)

Policastro, Lucia L.; Duran, Hebe; Molinari, Beatriz L.; Somacal, Hector R.; Valda, Alejandro A.

2003-01-01

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

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

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

2005-01-01

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

Clinical and Functional Assays of Radiosensitivity and Radiation-Induced Second Cancer

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Mohammad Habash

2017-10-01

Full Text Available Whilst the near instantaneous physical interaction of radiation energy with living cells leaves little opportunity for inter-individual variation in the initial yield of DNA damage, all the downstream processes in how damage is recognized, repaired or resolved and therefore the ultimate fate of cells can vary across the population. In the clinic, this variability is observed most readily as rare extreme sensitivity to radiotherapy with acute and late tissue toxic reactions. Though some radiosensitivity can be anticipated in individuals with known genetic predispositions manifest through recognizable phenotypes and clinical presentations, others exhibit unexpected radiosensitivity which nevertheless has an underlying genetic cause. Currently, functional assays for cellular radiosensitivity represent a strategy to identify patients with potential radiosensitivity before radiotherapy begins, without needing to discover or evaluate the impact of the precise genetic determinants. Yet, some of the genes responsible for extreme radiosensitivity would also be expected to confer susceptibility to radiation-induced cancer, which can be considered another late adverse event associated with radiotherapy. Here, the utility of functional assays of radiosensitivity for identifying individuals susceptible to radiotherapy-induced second cancer is discussed, considering both the common mechanisms and important differences between stochastic radiation carcinogenesis and the range of deterministic acute and late toxic effects of radiotherapy.

Cell lines radiosensitization of thyroid cancer by histone deacetylase inhibitors

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Perona, M; Dagrosa, M A; Rossich, L; Casal, M; Pisarev, M A; Thomasz, L; Juvenal G J

2012-01-01

Introduction: Thyroid cancer is the most common endocrine neoplasia. Surgical resection and radioactive iodine is an effective treatment for well-differentiated tumors. Histone deacetylase inhibitors (HDAC-I) are agents that cause hyperacetylation of histone proteins and as a consequence remodeling of chromatin structure. They can induce growth arrest, differentiation and apoptotic cell death in different tumor cells. The use of HDAC-I agents could be of utility to enhance the response to external radiation therapy of those thyroid cancers that are refractory to most conventional therapeutic treatments. Objective: To study the effect of HDAC-I as radiosensitizers for the treatment of thyroid cancer and their ability to induce differentiation of thyroid cancer cells. Materials and methods: The human thyroid follicular (WRO) and papillary (TPC-1) carcinoma cell lines were seeded and incubated with increasing doses (0, 0.3, 0.5, 1 and 1.5 mM) of the HDAC-I sodium butirate (NaB) and valproic acid (VA) to evaluate cell proliferation and iodide uptake. Cells were irradiated with a 60 Co γ-ray source (1 ± 5% Gy/min) and postirradiation survival was quantified with the colony formation assay. Survival fraction at 2 Gy (SF2) was calculated for each cell line. Cell cycle and cell death were evaluated at a dose of 3 Gy. Iodide uptake, PCR analysis and transient transfection studies were performed. Results: Cell proliferation was not significantly suppressed after 24 hours of incubation with both drugs at all assayed doses. Iodide uptake was not modified after incubation with HDAC-I of both cell lines. SF2 was reduced from 68 ± 1.6 % in the control WRO cells to 42 ± 3.8 % (P<0.001) in NaB-treated cells. In TPC-1 SF2 was reduced from 32 ± 1.1 % in the control cells to 24 ± 0.8 % (P<0.01). In VA-treated cells SF2 was reduced from 69 ± 0.02 % in control WRO cells to 56 ± 0.01 % (P<0.01) and from 31 ± 2 % in control TPC-1 cells to 11 ± 1 % (P<0.01). There was an arrest

Glutathione in the modulation of radiosensitivity: a review

International Nuclear Information System (INIS)

Umadevi, P.; Prasanna, P.G.S.

1993-01-01

Glutathione (γ - glutamyl cysteinyl glycine, GSH) constitutes the major low molecular weight thiol compound in the mammalian cells. GSH has been assigned an important role in determining the inherent radiosensitivity of cells. Endogenous GSH involved in a number of radiation induced chemical processes, which help in the repair of radiation injury to the target molecules. Experimental evidence suggests that GSH competes with molecular oxygen in the cells to prevent fixation of DNA damage. Certain chemicals like buthionine sulfoximine are found to deplete the cellular GSH content by interactions at specific sites in the GSH cycle. It may be possible to take advantage of this phenomenon by increasing the radiosensitivity of hypoxic tumor cells, without seriously affecting the normal cells, so as to increase the therapeutic efficiency of radiation treatment. (author). 52 refs., 1 fig

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

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Kato, Kengo; Kashiwakura, Ikuo; Kuwabara, Mikinori

2011-01-01

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 10 5 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)

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

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Werner, F.; Zoelzer, F.; Streffer, C.

2001-01-01

Background: The tumor suppressor protein p53 which can mediate an ionizing radiation-induced G 1 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 G 1 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 G 1 arrest and had a relatively high radiosensitivity, whereas the strain with a low p53 level showed a significant G 1 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 G 1 arrest is one of the factors determining radiosensitivity. (orig.) [de

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

International Nuclear Information System (INIS)

Liu Xiaoqun; Qiao Tiankui

2014-01-01

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 A 549 cells. Methods: Eukaryotic expression plasmid containing ATM small interfering RNA (siRNA) (pSilencer2.1-ATM), as well as pSilencer2.1-nonspecific, was constructed.Lung adenocarcinoma A 549 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 (D 0 ratios) for the positive group and negative group were 1.50 and 1.01, respectively. The flow cytometry revealed that the proportions of A 549 cells in G 1 and G 2 /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 A 549 cells, probably by affecting the cell cycle and promoting cell apoptosis. (authors)

antiEGFR conjugated gold nanoparticles for increasing radiosensitivity in lung cancer cells

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Pujari, Geetanjali; Sarma, Asitikantha; Avasthi, Devesh K.

2014-01-01

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 12 C 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)

Transfection of wild type ADVP53 gene into human brain tumor cell lines has a radiosensitizing effect independent of apoptosis

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Geng, L.; Walter, S; Vaughan, A.T.M.

1997-01-01

Purpose: Despite attempts with a variety of therapeutic approaches there has been little impact on the survival of patients with Glioblastoma multiforme, with median survivals reported of approximately 12 months. In this study a replication restricted adenovirus vector is used to transfer the wild type p53 gene into two cell lines derived from a human astrocytoma U87MG or glioblastoma T98G, to determine its ability to act as a radiosensitizer in conjunction with conventional radiotherapy. Methods: An adenovirus vector containing the human wild type p53 (Advp53) gene was used in addition to a control vector containing the β-galactosidase (Advγgal) reporter gene. To achieve cellular incorporation both vectors were incubated with cells for 30 minutes - washed and returned to culture. The successful incorporation of each vector was determined by either a p53 assay using either a western blotting or flow cytometry techniques, or specific staining for β-galactosidase activity. The presence of each vector was assayed until the constructs were eliminated from the cell. To determine the effects of these vectors on cell survival sufficient vector was added to produce a measurable reduction in clonogenic survival and this value was used in subsequent irradiation experiments. To determine the ability of wild type p53 to induce apoptosis the cells were examined from 1 to 5 days after irradiation by H and E staining for the characteristic morphology indicating an apoptotic process. Results: Both the Advp53 and Advβgal vectors were successfully incorporated into each cell line. Expression of each gene was reduced to approximately half by 5 days and virtually eliminated by 15 days after transfection in both lines. At the doses used the wild type Advp53 adenovirus was toxic to both cell lines giving surviving fractions between 39-74%. When this toxicity was taken into account the presence of the Advp53 gene had a radiosensitizing effect in each cell line. To determine the

Reduction of nitric oxide level enhances the radiosensitivity of hypoxic non-small cell lung cancer

International Nuclear Information System (INIS)

Saleem, Wael; Suzuki, Yoshiyuki; Mobaraki, Abdulelah; Yoshida, Yukari; Noda, Shinei; Saitoh, Jun-ichi; Nakano, Takashi

2011-01-01

The epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (E-TKI) resistance has emerged as an important clinical issue. To overcome this resistance, researchers have examined different modalities, either for use as a monotherapy or in combination with E-TKI therapy. In the present study, we investigated whether a decrease in nitric oxide (NO) levels affects the radiosensitization of non-small cell lung cancer (NSCLC) cell lines. A549 and H3255 NSCLC cells were examined. They were subjected to hypoxic conditions and monotherapy, or combined therapy using radiation and N G -monomethyl- L -arginine, monoacetate (LNMMA). Reductions in nitric oxide levels enhanced the radiosensitivity of both cell lines and significantly reduced the expression of both hypoxia-inducible factor-1α (HIF-1α) and EGFR in H3255 cells compared to A549 cells. Since NO is significantly associated with cell metabolism, we measured the levels of pyruvate dehydrogenase kinase-1 (PDK-1), reactive oxygen species, and oxygen and observed that the expression of PDK-1 was significantly reduced. This reduction was seen simultaneously after the silencing of HIF-1α; however, not following LNMMA treatment. The oxygen concentration was significantly increased in the treated cells, and their viability decreased in parallel. Reactive oxygen species were decreased after LNMMA and radiation treatment. Adding EGFR-TKI to cells with reduced NO levels further suppressed cell viability when combined with radiation. This study suggests that a reduction in the NO level might substantially overcome the radioresistance of mutant NSCLC cells. (author)

Increased radiosensitivity and radiothermosensitivity of human pancreatic MIA PaCa-2 and U251 glioblastoma cell lines treated with the novel Hsp90 inhibitor NVP-HSP990

International Nuclear Information System (INIS)

Milanović, Dušan; Firat, Elke; Grosu, Anca Ligia; Niedermann, Gabriele

2013-01-01

Heat shock Protein 90 (Hsp90) is a molecular chaperone that folds, stabilizes, and functionally regulates many cellular proteins involved in oncogenic signaling and in the regulation of radiosensitivity. It is upregulated in response to stress such a heat. Hyperthermia is a potent radiosensitizer, but induction of Hsp90 may potentially limit its efficacy. Our aim was to investigate whether the new Hsp90 inhibitor NVP-HSP990 increases radiosensitivity, thermosensitivity and radiothermosensitivity of human tumor cell lines. U251 glioblastoma and MIA PaCa-2 pancreatic carcinoma cells were used. To determine clonogenic survival, colony forming assays were performed. Cell viability and proliferation were assesed by Trypan blue staining. Cell cycle and apoptosis analyses were performed by flow cytometry. DAPI staining was used to detect mitotic catastrophe. NVP-HSP990 increased the thermosensitivity, radiosensitivity and radio-thermosensitivity of both cell lines in clonogenic assays. 72 hours after irradiation with 4 Gy, a significant reduction in cell number associated with considerable G2/M acumulation and mitotic catastrophe as well as cell death by apoptosis/necrosis was observed. Treatment with NVP-HSP990 strongly sensitized U251 and MIA PaCa-2 cells to hyperthermia and ionizing radiation or combination thereof through augmentation of G2/M arrest, mitotic catastrophe and associated apoptosis

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

International Nuclear Information System (INIS)

Smeets, M.F.M.A.; Mooren, E.H.M.; Begg, A.C.

1993-01-01

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)

Radiosensitization of tumors and normal tissues by combined treatment with misonidazole and heat

International Nuclear Information System (INIS)

Hofer, K.G.; MacKinnon, A.R.; Schubert, A.L.; Lehr, J.E.; Grimmett, E.V.

1981-01-01

Combination treatment of mice with misonidazole (0.5 mg/g body wt.) and hyperthermia (41.5/sup o/C for 45 mins.) produced dramatic radiosensitization in hypoxic BP-8 murine sarcoma cells. The dose modifying factor (DMF: 4.3) was such that hypoxic BP-8 cells subjected to combination therapy became more radiosensitive than untreated, fully oxygenated cell populations. In contrast, radiosensitization by combination treatment was comparatively minor or completely absent in normal body tissues such as skin (DMF: 1.57), intestine (DMF: 1.0), and bone marrow (DMF: 1.0). These results suggest that simultaneous administration of misonidazole and hyperthermia may prove an effective adjuvant to conventional clinical radiation therapy

Ellagic acid radiosensitizes tumor cells by evoking apoptotic pathway

International Nuclear Information System (INIS)

Ahire, Vidhula R.; Mishra, K.P.

2016-01-01

Cancer causes millions of deaths each year globally. In most patients, the cause of treatment failure is found associated with the resistance to chemotherapy and radiotherapy. The development of tumor cell resistance evokes multiple intracellular molecular pathways. In addition, the limitation in treatment outcome arises due to unintended cytotoxic effects of the synthetic anticancer drugs to normal cells and tissues. Considerable focus of research is, therefore, devoted to examine plant-based herbal compounds which may prove potential anticancer drug for developing effective cancer therapy. Research results from our laboratory have shown that ellagic acid (EA), a natural flavonoid displays enhanced tumor toxicity in combination with gamma radiation to many types of cancers in vitro as well as in vivo. Studies on the underlying mechanisms of toxicity suggest that EA employs the cellular signaling pathways in producing the observed effects. This paper gives an account of molecular mechanisms of EA-induced apoptosis process in tumor cytotoxicity. It is suggested that EA acts as a novel radiosensitizer for tumors and a radioprotector for normal cells which may offer a novel protocol for cancer treatment. (author)

Autophagy influences the low-dose hyper-radiosensitivity of human lung adenocarcinoma cells by regulating MLH1.

Science.gov (United States)

Wang, Qiong; Xiao, Zhuya; Lin, Zhenyu; Zhou, Jie; Chen, Weihong; Jie, Wuyun; Cao, Xing; Yin, Zhongyuan; Cheng, Jing

2017-06-01

To investigate the impact of autophagy on the low-dose hyper-radiosensitivity (HRS) of human lung adenocarcinoma cells via MLH1 regulation. Immunofluorescent staining, Western blotting, and electron microscopy were utilized to detect autophagy in A549 and H460 cells. shRNA was used to silence MLH1 expression. The levels of MLH1, mTOR, p-mTOR, BNIP3, and Beclin-1 were measured by real-time polymerase chain reaction (PCR) and Western blotting. A549 cells, which have low levels of MLH1 expression, displayed HRS/induced radioresistance (IRR). Conversely, the radiosensitivity of H460 cells, which express high levels of MLH1, conformed to the linear-quadratic (LQ) model. After down-regulating MLH1 expression, A549 cells showed increased HRS and inhibition of autophagy, whereas H460 cells exhibited HRS/IRR. The levels of mTOR, p-mTOR, and BNIP3 were reduced in cells harboring MLH1 shRNA, and the changes in the mTOR/p-mTOR ratio mirrored those in MLH1 expression. Low MLH1-expressing A549 cells may exhibit HRS. Both the mTOR/p-mTOR and BNIP3/Beclin-1 signaling pathways were found to be related to HRS, but only mTOR/p-mTOR is involved in the regulation of HRS via MLH1 and autophagy.

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

International Nuclear Information System (INIS)

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

1981-01-01

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

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

International Nuclear Information System (INIS)

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

1993-01-01

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

Radiosensitization by hematocrit manipulation

International Nuclear Information System (INIS)

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

1985-01-01

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

Radiation dose rate affects the radiosensitization of MCF-7 and HeLa cell lines to X-rays induced by dextran-coated iron oxide nanoparticles.

Science.gov (United States)

Khoshgard, Karim; Kiani, Parvaneh; Haghparast, Abbas; Hosseinzadeh, Leila; Eivazi, Mohammad Taghi

2017-08-01

The aim of radiotherapy is to deliver lethal damage to cancerous tissue while preserving adjacent normal tissues. Radiation absorbed dose of the tumoral cells can increase when high atomic nanoparticles are present in them during irradiation. Also, the dose rate is an important aspect in radiation effects that determines the biological results of a given dose. This in vitro study investigated the dose-rate effect on the induced radiosensitivity by dextran-coated iron oxide in cancer cells. HeLa and MCF-7 cells were cultured in vitro and incubated with different concentrations of dextran-coated iron oxide nanoparticles. They were then irradiated with 6 MV photons at dose rates of 43, 185 and 370 cGy/min. The MTT test was used to obtain the cells' survival after 48 h of irradiations. Incubating the cells with the nanoparticles at concentrations of 10, 40 and 80 μg/ml showed no significant cytotoxicity effect. Dextran-coated iron oxide nanoparticles showed more radiosensitivity effect by increasing the dose rate and nanoparticles concentration. Radiosensitization enhancement factors of MCF-7 and HeLa cells at a dose-rate of 370 cGy/min and nanoparticles' concentration of 80 μg/ml were 1.21 ± 0.06 and 1.19 ± 0.04, respectively. Increasing the dose rate of 6 MV photons irradiation in MCF-7 and HeLa cells increases the radiosensitization induced by the dextran-coated iron nanoparticles in these cells.

In vitro radiosensitizing effects of ultrasmall gadolinium based particles on tumour cells.

Science.gov (United States)

Mowat, P; Mignot, A; Rima, W; Lux, F; Tillement, O; Roulin, C; Dutreix, M; Bechet, D; Huger, S; Humbert, L; Barberi-Heyob, M; Aloy, M T; Armandy, E; Rodriguez-Lafrasse, C; Le Duc, G; Roux, S; Perriat, P

2011-09-01

Since radiotherapy is widely used in cancer treatment, it is essential to develop strategies which lower the irradiation burden while increasing efficacy and become efficient even in radio resistant tumors. Our new strategy is relying on the development of solid hybrid nanoparticles based on rare-earth such as gadolinium. In this paper, we then evidenced that gadolinium-based particles can be designed to enter efficiently into the human glioblastoma cell line U87 in quantities that can be tuned by modifying the incubation conditions. These sub-5 nm particles consist in a core of gadolinium oxide, a shell of polysiloxane and are functionalized by diethylenetriaminepentaacetic acid (DTPA). Although photoelectric effect is maximal in the [10-100 keV] range, such particles were found to possess efficient in-vitro radiosensitizing properties at an energy of 660 keV by using the "single-cell gel electrophoresis comet assay," an assay that measures the number of DNA damage that occurs during irradiation. Even more interesting, the particles have been evidenced by MTT assays to be also efficient radiosensitizers at an energy of 6 MeV for doses comprised between 2 and 8 Gy. The properties of the gadolinium-based particles give promising opening to a particle-assisted radio-therapy by using irradiation systems already installed in the majority of hospitals.

Enhancement of misonidazole radiosensitization by an inhibitor of glutathione biosynthesis

International Nuclear Information System (INIS)

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

1983-01-01

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

Lack of dependence of 5-fluorodeoxyuridine-mediated radiosensitization on cytotoxicity

International Nuclear Information System (INIS)

Lawrence, T.S.; Davis, M.A.; Chang, E.Y.

1995-01-01

It has been proposed that fluoropyrimidine-mediated cytotoxicity and radiosensitization are closely correlated. We have shown that HT29 human colon cancer cells transfected with the E. coli dUTPase gene are resistant to 5-fluorodeoxyuridine (FdUrd)-mediated cytotoxicity, presumably through more effective elimination of dUTP. We used these cells to assess the association between radiosensitization and cytotoxicity produced by FdUrd. The radiation sensitivities of the clones expressing elevated dUTPase activity (dutE clones) were similar to those of untransfected HT29 cells or HT29 cells which has been transfected with only the expression vector for the E. coli gene (con clones). We found that FdUrd produced similar increases in radiation sensitivity regardless of dUTPase activity. Levels of dUTPase in the dutE clones remained elevated during the entire period of FdUrd exposure, demonstrating that the lack of difference between dutE and Con clones was not a reflection of down-regulation of dUTPase activity by FdUrd, Flow cytometry showed that all clones progressed past the G 1 /S-phase boundary and into early S phase during FdUrd treatment. These data suggest that the mechanisms of FdUrd-mediated cytotoxicity and radiosensitization are not closely linked. These findings, combined with our previous investigations, are consistent with the hypothesis that radiosensitization occurs in cells which progress past the G 1 /S-phase boundary in the presence of FdUrd. 24 refs., 2 figs., 2 tabs

Individual radiosensitivity does not correlate with radiation-induced apoptosis in lymphoblastoid cell lines or CD{sup 3+} lymphocytes

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Wistop, A.; Keller, U.; Grabenbauer, G.G.; Sauer, R.; Distel, L.V.R. [Dept. of Radiation Oncology, Friedrich Alexander Univ. Erlangen-Nuremberg, Erlangen (Germany); Sprung, C.N. [Div. of Research, Peter MacCallum Cancer Centre, East Melbourne, VIC (Australia)

2005-05-01

Background and purpose: spontaneous and radiation-induced apoptosis of lymphoblastoid cell lines (LCLs) derived from healthy donors, cancer patients and donors with radiosensitivity syndromes as well as CD{sup 3+} lymphocytes from patients with {>=} grade 3 late toxicity were investigated as a possible marker for the detection of individual radiosensitivity. These investigations are based on the hypothesis that hypersensitive patients have reduced levels of apoptosis after in vitro irradiation as a result of a defect in the signaling pathway. Material and methods: Epstein-Barr virus-(EBV-)transformed LCLs derived from five healthy donors, seven patients with heterozygous or homozygous genotype for ataxia-telangiectasia or Nijmegen breakage syndrome and five patients with {>=} grade 3 late toxicity (RTOG) were investigated. In addition, CD{sup 3+} lymphocytes from 21 healthy individuals and 18 cancer patients including five patients with a proven cellular hypersensitivity to radiation were analyzed. Cells were irradiated in vitro with a dose of 2 and 5 Gy and were incubated for 48 h. Apoptotic rates were measured by the TUNEL assay followed by customized image analysis. Results: four out of seven radiosensitivity syndrome patients were identified to have an increased cellular radiosensitivity as determined by reduced apoptotic rates after irradiation of their respective LCLs. Comparatively, only two of the five hypersensitive cancer patients were clearly identified by reduced apoptotic rates. Spontaneous apoptotic rates were very homogeneous among all 39 samples from controls and patients, while lymphocytes of all cancer patients showed significantly lower radiation-induced rates. Conclusion: only a subgroup of hypersensitive patients may be identified by reduction of radiation-induced apoptotic rate. It is concluded that the hypothesis according to which hypersensitive cells have reduced levels of apoptosis is only conditionally true. The authors suggest that this

Cytogenetic characterization of low-dose hyper-radiosensitivity in Cobalt-60 irradiated human lymphoblastoid cells

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Joshi, Gnanada S. [Department of Biological Sciences, Wayne State University, Detroit, MI 48202 (United States); Joiner, Michael C. [Department of Radiation Oncology, Wayne State University, Detroit, MI 48201 (United States); Tucker, James D., E-mail: jtucker@biology.biosci.wayne.edu [Department of Biological Sciences, Wayne State University, Detroit, MI 48202 (United States)

2014-12-15

Highlights: • Human cells were irradiated in G1 or G2 and evaluated for micronuclei and bridges. • Cells irradiated in G2 but not in G1 exhibit low dose hyper-radiosensitivity. • Response curves of cells irradiated in G2 do not fit a linear-no-threshold model. • Response curves of cells irradiated in G1 fit a linear-no-threshold model. - Abstract: The dose-effect relationships of cells exposed to ionizing radiation are frequently described by linear quadratic (LQ) models over an extended dose range. However, many mammalian cell lines, when acutely irradiated in G2 at doses ≤0.3 Gy, show hyper-radiosensitivity (HRS) as measured by reduced clonogenic cell survival, thereby indicating greater cell lethality than is predicted by extrapolation from high-dose responses. We therefore hypothesized that the cytogenetic response in G2 cells to low doses would also be steeper than predicted by LQ extrapolation from high doses. We tested our hypothesis by exposing four normal human lymphoblastoid cell lines to 0–400 cGy of Cobalt-60 gamma radiation. The cytokinesis block micronucleus assay was used to determine the frequencies of micronuclei and nucleoplasmic bridges. To characterize the dependence of the cytogenetic damage on dose, univariate and multivariate regression analyses were used to compare the responses in the low- (HRS) and high-dose response regions. Our data indicate that the slope of the response for all four cell lines at ≤20 cGy during G2 is greater than predicted by an LQ extrapolation from the high-dose responses for both micronuclei and bridges. These results suggest that the biological consequences of low-dose exposures could be underestimated and may not provide accurate risk assessments following such exposures.

Chromosomal radiosensitivity of prostate cancer patients

International Nuclear Information System (INIS)

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

2003-01-01

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

Heat shock protein 90 chaperone complex inhibitor enhanced radiosensitivity through modification of response to hormone and degradation of androgen receptor in hormone sensitive prostate cancer cell line

International Nuclear Information System (INIS)

Mitsuhashi, N.; Harashima, K.; Akimoto, T.

2003-01-01

It is easily speculated that androgen or androgen deprivation affects proliferative activity or radiosensitivity, but there has been enough information how androgen or androgen deprivation influences the response to radiation. In this setting, the effect of dihydrotestosterone (DHT) on cellular growth and radiosensitivity was examined in hormone-responsive human prostate cancer cell line (LnCap). The binding of androgen receptor (AR) with heat shock protein 90 (Hsp90) plays an important role in stability of the function of receptor. It was, therefore, examined how Hsp90 chaperone complex inhibitor modified the effect of DHT on radiosensitivity in addition to the effect of DHT, especially focusing on AR and its downstream signal transduction pathways. Hydroxy-flutamide (OH-flutamide) was also used to confirm the effect of activation of AR on radiosensitivity because AR of LnCap has a point mutation, leading to activation of AR caused by the binding of OH-flutamide. Radicicol was used as a Hsp90 chaperone complex inhibitor, and incubated with cells at a concentration of 500 nM. Radicicol was incubated with cells for 9 h, and cells were irradiated 1 h after the start of incubation. DHT and OH-flutamide were incubated with cells until staining. DHT or OH-flutamide resulted in stimulation of cellular growth in contrast to inhibition of cellular growth caused by higher concentrations, so that we adopted 1 nM as a concentration of DHT and 1μM as a concentration of OH-flutamide. DHT or OH-flutamide in combination with radiation resulted in slight decrease in radiosensitivity compared with radiation alone. Radicicol at a concentration of 500 nM in combination with DHT or OH-flutamide abolished decrease in radiosensitivity caused by DHT or OH-flutamide. In terms of the expression of AR, radicicol in combination with radiation and/or DHT, OH-flutamide induced degradation of AR. In consistent with degradation of AR, the expression of prostate specific antigen (PSA) decreased

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

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

2012-04-15

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

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

International Nuclear Information System (INIS)

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

2012-01-01

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

Radiosensitivity of pulmonary alveolar macrophages in rats exposed to local X-irradiation

International Nuclear Information System (INIS)

Gong Yifen; Fei Lihua; Wu Dechang

1987-01-01

The radiosensitivity of pulmonary alveolar macrophages (PAMs) in rats exposed to local thoracic X-irradiatoin was studied. The percentages of mitotic and labeling cells were used as biological endpoints. The parameters of radiosensitivity of PAMs obtained on the second day after local exposure are as follows: D 0 = 0.68 Gy, Dq = 0.06 Gy, n = 1.1 for mitotic cells and D 0 = 1.04 Gy, Dq = 0.12 Gy, n = 1.12 for labeling cells. The parameters of radiosensitivity of PAMs in bronchical lavage obtained immediately after X-irradiation are: D 0 = 3.56 Gy, Dq = 0.77 Gy, n = 1.24 for labeling cells and D 0 = 3.69 Gy, Dq = 0.35 Gy, n = 1.1 for mitotic cells. The comparison of thses results indicates that the radiation effect on PAMs obtained immediately after X-irradiation is less severe than that of PAMs obtained 2 days later. It might be caused by the delay of cell cycle within 2 days after X-irradiation

Differential response of DU145 and PC3 prostate cancer cells to ionizing radiation: role of reactive oxygen species, GSH and Nrf2 in radiosensitivity.

Science.gov (United States)

Jayakumar, Sundarraj; Kunwar, Amit; Sandur, Santosh K; Pandey, Badri N; Chaubey, Ramesh C

2014-01-01

Radioresistance is the major impediment in radiotherapy of many cancers including prostate cancer, necessitating the need to understand the factors contributing to radioresistance in tumor cells. In the present study, the role of cellular redox and redox sensitive transcription factor, Nrf2 in the radiosensitivity of prostate cancer cell lines PC3 and DU145, has been investigated. Differential radiosensitivity of PC3 and DU145 cells was assessed using clonogenic assay, flow cytometry, and comet assay. Their redox status was measured using DCFDA and DHR probes. Expression of Nrf2 and its dependent genes was measured by EMSA and real time PCR. Knockdown studies were done using shRNA transfection. PC3 and DU145 cells differed significantly in their radiosensitivity as observed by clonogenic survival, apoptosis and neutral comet assays. Both basal and inducible levels of ROS were higher in PC3 cells than that of DU145 cells. DU145 cells showed higher level of basal GSH content and GSH/GSSG ratio than that of PC3 cells. Further, significant increase in both basal and induced levels of Nrf2 and its dependent genes was observed in DU145 cells. Knock-down experiments and pharmacological intervention studies revealed the involvement of Nrf2 in differential radio-resistance of these cells. Cellular redox status and Nrf2 levels play a causal role in radio-resistance of prostate cancer cells. The pivotal role Nrf2 has been shown in the radioresistance of tumor cells and this study will further help in exploiting this factor in radiosensitization of other tumor cell types. © 2013.

Study on the relationship between DNA-PKcs and genomic instability and hyper-radiosensitivity

International Nuclear Information System (INIS)

Yang Kang; Zhu Jiayun; Ding Nan; Li Junhong; Hu Wentao; Su Fengtao; He Jinpeng; Li Sha

2010-01-01

To investigate the relationship between DNA-PKcs and genome instability and hyper-radiosensitivity, human glioma cell lines M059K and M059J, as a model expressing wild-type DNA-PKcs and a model defective in DNA-PKcs activity, were exposed to low doses of X-rays. Cells survival fractions were assessed by colony-forming assay and Cytochalasin-B micronucleus assay was employed to detect the genomic instability happening in each single irradiated colony. It has been found that as the post-incubation time increased, M059K cells expressing wild-type DNA-PKcs exhibited low-dose hyper-radiosensitivity and showed a similar genomic instability after 0.2 Gy and 0.6 Gy irradiations, but the M059J cells lacking in DNA-PKcs didn't present low-dose hyper-radiosensitivity and showed a higher genomic instability of 0.6 Gy than that of 0.2 Gy. The results indicate that DNA-PKcs may act as one of the key factors that lead to low-dose hyper-radiosensitivity. (authors)

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

International Nuclear Information System (INIS)

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

1994-01-01

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