X-RAY-SENSITIVE MUTANTS OF MOUSE MAMMARY CARCINOMA CELLS ARE HYPERSENSITIVE TO BLEOMYCIN AND HYDROGEN PEROXIDE

Abstract

Radiation-sensitive mutants, SX9 and SX10, were isolated from mouse mammary carcinoma FM3A cells. The mutant SX9 complemented another radiation-sensitive strain M10 of mouse leukemia L5178Y cells, but SX10 did not. SX9 and SX10 cells were more sensitive than the wild-type cells to the lethal effects of bleomycin. The frequency of X-ray-induced mutations to 6-thioguanine resistance was much higher in SX9 cells than in the wild-type cells in the dose range up to 1 Gy, although the induced mutant frequencies were not very different between these two cell strains when compared at equivalent survival. SX9, SX10 and M10 cells were found to be far more sensitive than the respective wild-type cells to hydrogen peroxide inactivation, but the levels of catalase activity were similar among these cell strains. These mutants should be useful for cloning and identifying the human genes responsible for radiation sensitivity.