INCREASING THE SUSCEPTIBILITY OF THE RAT 208F FIBROBLAST CELL-LINE TORADIATION-INDUCED APOPTOSIS DOES NOT ALTER ITS CLONOGENIC SURVIVAL DOSE - RESPONSE

Recent studies have suggested a correlation between the rate and incid ence of apoptosis and the radiation response of particular cell lines. However, we found that increasing the rate of induction of apoptosis in the fibroblast line 208F, by transfecting it with human c-myc, did not lead to a change in its clonogenic survival dose-response for eith er gamma-irradiation or I-125-induced DNA damage. It was also found th at expression of mutant (T24) Ha-ras in the 208F line appeared to decr ease the level of apoptosis per mitosis after irradiation and inhibite d the formation of nucleosomal ladders, but did not affect either the onset of the morphological features of apoptosis or the clonogenic sur vival dose-response of the cells to either gamma-irradiation or I-125- induced DNA damage. Our findings suggest that it may be incorrect to m ake predictions about the radiosensitivity of cells based only on know ledge of their mode of death.