Abstract:

To detect the inhibitory effects of ionizing radiation combined with autophagy and apoptosis inhibitors and inducers on the proliferation of human breast cancer cell line.
Methods  MTT and flow cytometry (FCM) were used to detect the surviving and proliferation of MCF-7 cells，which were under 0,2,4,8 and 10 Gy X-ray radiation and different dealing methods 4 Gy,4 Gy + 3-MA,4 Gy + rapamycin,4 Gy + z-VAD-fmk,and   the relationship of dose-effects and time-effects was analyzed.
Results  With the increase of irradiation doses (4,8 and 10 Gy) and the elongation of irradiation time (48 and 72 h),the inhibitory rates of the  proliferation of breast cancer cells were increased ,there were significant differences between various groups(P<0.05 or P<0.01).The inhibitory rates of the proliferation of breast cancer cells in  4 Gy+3-MA or 4 Gy+ z-VAD-fmk groups  were significantly different from those in 4Gy+rapamycin group(P<0.05 or P<0.01),and there were significant differences after treated for  24,48 and 72 h between various groups (P<0.05 or P<0.01).Conclusion Ionizing radiation in combination with autophagy inducer could induced the autophagy in human breast cancer cells and promote the apoptosis;the ionizing radiation in combination with autophagy inhibitor or apoptosis inhibitor could inhibit the apoptosis.Thus,ionizing  radiation can induce the autophagy in human breast cancer cells,and promote the apoptosis.

Key words: ionizing radiation;autophagy;cell apoptosis;breast neoplasms