RADIATION-INDUCED APOPTOTIC CELL-DEATH IN HUMAN GASTRIC EPITHELIAL TUMOR-CELLS - CORRELATION BETWEEN MITOTIC DEATH AND APOPTOSIS

The mode of cell death in cells undergoing mitotic death after gamma-i rradiation was studied in seven human gastric epithelial tumour cell l ines and two strains of normal gastric fibroblasts. Apoptotic cells we re frequently observed in all tumour lines after irradiation, whereas the two fibroblast strains were quite low in apoptosis frequency. The advent of apoptosis depended on the radiation doses and incubation tim e. Detailed analysis of one of the carcinoma lines, SH101-P4, revealed that G(2)-phase arrest was maximum at 12 h postirradiation. The cells began to escape G(2) arrest by 24 h. Apoptotic cells began to increas e at 12 h postirradiation and became maximal from 72 to 96 h. Apoptosi s developed in the G(1) phase of the cell cycle subsequent to the irra diation. These results suggest that apoptosis is one of the modes of m itotic death after irradiation.