Examining the non-homologous repair process following cisplatin and radiation treatments

Purpose : To investigate the extent of non-homologous end-joining (NHEJ) in the mechanism of cisplatin radiosensitization. Materials and methods : Ku80-deficient cells are deficient in the non-homologous DNA double-strand break repair process, while the wild-type MEF cells maintain full mammalian cell repair capabilities. Both cell lines were exposed to clinically applicable doses of cisplatin (1, 3 and 6 μ g ml -1) for 1 h immediately before exposure to 250 kV X-rays. Radiation responses were plotted for each cell line and for all doses of cisplatin to observe relative levels of radiosensitization. Split-dose experiments were also performed on each cell line to measure levels of sublethal damage repair. Results : Radiosensitization was observed in the wild-type cells but not in the Ku80 cells when treated with a combination of 1 μ g ml -1 cisplatin followed by X-rays, implying that the NHEJ pathway may play a large role in cisplatin radiosensitization. Concurrent administration of this cisplatin dose wit...