Host: The Japan Radiation Research Society, Chairman of the 52nd Annual Meeting, Toshiteru Okubo (Radiation Effects Research Foundation)
Apoptosis is a well-known mode of cell death induced by ionizing radiation (IR). Our previous findings demonstrated that a major mode of IR-induced cell death in normal human fibroblasts was non-apoptotic type, that is, SLGA, which suggested a possibility of SLGA-induction in tumor cell exposed to IR. Here, we performed live-imaging analysis to examine a mode of cell death induced in individual breast carcinoma cells (MCF-7) exposed to 10Gy of X-irradiation.
We found that the majority of IR-induced cell death was a non-apoptotic mode. About 60 % of irradiated MCF-7 failed to enter into mitosis during 5 days incubation after IR, and they showed enlarged cytoplasm with mononuclear. Other 40 % of irradiated MCF-7 also failed to divide up to approximately 20 hrs after irradiation. Then, they started cell division and induced mitotic catastrophe. Interestingly, these cells underwent abnormal cell dividion, frequently fused again and swelled up cytoplasm with multi-nuclear. More than 70 % of cells were positive for senescence-associated ß-galactosidase, by which senescent cells were detected, subsequently, 20 % of all irradiated cells induced necrosis. These results suggest that SLGA-induction contributes to cell death by IR and to radiosensitivity in tumor cells.
