Cellular response to fludarabine treatment in combination with different ionizing radiation in renal carcinoma 786-O cells

Objective To investigate DNA double-strand breaks and radiosensitization in renal carcinoma 786-O cells induced by fludarabine (FA) combined with different ionizing radiations. Methods The 786-O cells were exposed to FA combined with X-ray or heavy ion beam irradiation. Flow cytometry was used to evaluate the percentage of γH2AX-positive cells and cell cycle. The neutral comet assay was used to detect DNA double-strand breaks. The colony-forming assay was used to evaluate the effects of different treatments on cell survival. Comparison between groups was made by one-way analysis of variance or Dunnet’s t test. Results Compared with FA alone or irradiation alone, FA combined with different ionizing radiations increased DNA double-strand breaks as shown by significantly increased levels of γH2AX (P=0.007, 0.001); FA combined with heavy ion beam irradiation lead to a cell cycle block at the radiosensitive G2/M phase and significantly increased the expression of γH2AX in the G2/M phase (P=0.000, 0.000); the neutral comet assay revealed that FA combined with irradiation significantly increased DNA sublethal damage (P=0.020, 0.060); FA significantly reduced the colony-forming rate after irradiation (P=0.000, 0.030; 0.001, 0.040). Conclusions FA enhances the effects induced by X-ray and heavy ion beam irradiation with different properties. Particularly, FA substantially enhances the cell death induced by heavy ion beam irradiation. Key words: Deoxyribonucleic acid damage; Fludarabine; Heavy ion beam; X-ray; 786-O cell line