%0 Journal Article %T Impact of dose-rate on the low-dose hyper-radiosensitivity and induced radioresistance (HRS/IRR) response. %+ Centre de Recherche en Cancérologie de Lyon (UNICANCER/CRCL) %+ European Synchrotron Radiation Facility (ESRF) %+ Institut de recherche biomédicale des armées. Antenne Grenoble (IRBA [Grenoble]) %+ Centre de Lutte contre le Cancer Antoine Lacassagne [Nice] (UNICANCER/CAL) %A Thomas, Charles %A Jennifer, Martin %A Devic, Clément %A Bräuer-Krisch, Elke %A Diserbo, Michel %A Thariat, Juliette %A Foray, Nicolas %< avec comité de lecture %@ 0955-3002 %J International Journal of Radiation Biology %I Taylor and Francis %V 89 %N 10 %P 813-22 %8 2013-10 %D 2013 %R 10.3109/09553002.2013.800248 %M 23631649 %K Hyper-radiosensitivity (HRS) response %K induced radioresistance (IRR) response %K dose-rate %K DSB repair %K tumor cells %K radiotherapy %Z Life Sciences [q-bio]/Bioengineering/Nuclear medicineJournal articles %X PURPOSE: To ask whether dose-rate influences low-dose hyper- radiosensitivity and induced radioresistance (HRS/IRR) response in rat colon progressive (PRO) and regressive (REG) cells. METHODS: Clonogenic survival was applied to tumorigenic PRO and non-tumorigenic REG cells irradiated with (60)Co γ-rays at 0.0025-500 mGy.min(-1). Both clonogenic survival and non-homologous end-joining (NHEJ) pathway involved in DNA double-strand breaks (DSB) repair assays were applied to PRO cells irradiated at 25 mGy.min(-1) with 75 kV X-rays only. RESULTS: Irrespective of dose-rates, marked HRS/IRR responses were observed in PRO but not in REG cells. For PRO cells, the doses at which HRS and IRR responses are maximal were dependent on dose-rate; conversely exposure times during which HRS and IRR responses are maximal (t(HRSmax) and t(IRRmax)) were independent of dose-rate. The t(HRSmax) and t(IRRmax) values were 23 ± 5 s and 66 ± 7 s (mean ± standard error of the mean [SEM], n = 7), in agreement with literature data. Repair data show that t(HRSmax) may correspond to exposure time during which NHEJ is deficient while t(IRRmax) may correspond to exposure time during which NHEJ is complete. CONCLUSION: HRS response may be maximal if exposure times are shorter than t(HRSmax) irrespective of dose, dose-rate and cellular model. Potential application of HRS response in radiotherapy is discussed. %G English %2 https://inserm.hal.science/inserm-00868975/document %2 https://inserm.hal.science/inserm-00868975/file/IJRB2013.pdf %L inserm-00868975 %U https://inserm.hal.science/inserm-00868975 %~ INSERM %~ CNRS %~ UNIV-LYON1 %~ UNIV-COTEDAZUR %~ CRCL %~ UDL %~ UNIV-LYON