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Low-dose hyper-radiosensitivity of progressive and regressive cells isolated from a rat colon tumour: impact of DNA repair.

Abstract : PURPOSE: To ask whether highly metastatic sublines show more marked low-dose hyper-radiosensitivity (HRS) response than poorly metastatic ones. MATERIALS AND METHODS: The progressive (PRO) subline showing tumourigenicity and metastatic potential and the regressive (REG) subline showing neither tumourigenicity nor metastatic potential were both isolated from a parental rat colon tumour. Clonogenic survival, micronuclei and apoptosis, cell cycle distribution, DNA single- (SSB) and double-strand breaks (DSB) induction and repair were examined. RESULTS: HRS phenomenon was demonstrated in PRO subline. Before irradiation, PRO cells show more spontaneous damage than REG cells. After 0.1 Gy, PRO cells displayed: (i) More DNA SSB 15 min post-irradiation, (ii) more unrepaired DNA DSB processed by the non-homologous end-joining (NHEJ) and by the RAD51-dependent recombination pathways, (iii) more micronuclei, than REG cells while neither apoptosis nor p53 phosphorylation nor cell cycle arrest was observed in both sublines. CONCLUSIONS: HRS response of PRO subline may be induced by impairments in NHEJ repair that targets G(1) cells and RAD51-dependent repair that targets S-G(2)/M cells. The cellular consequences of such impairments are a failure to arrest in cell cycle, the propagation of damage through cell cycle, mitotic death but not p53-dependent apoptosis. Tumourigenic cells with high metastatic potential may preferentially show HRS response.
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Submitted on : Thursday, June 6, 2013 - 12:36:20 PM
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Charles Thomas, Josiane Charrier, Catherine Massart, Michel Cherel, Bernard Fertil, et al.. Low-dose hyper-radiosensitivity of progressive and regressive cells isolated from a rat colon tumour: impact of DNA repair.. International Journal of Radiation Biology, Informa Healthcare, 2008, 84 (7), pp.533-548. ⟨10.1080/09553000802195331⟩. ⟨inserm-00831027⟩



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