Effect of deficiencies in DNA repair on the toxicity of mitomycin C and porfiromycin to CHO cells under aerobic and hypoxic conditions.

A wild type Chinese hamster cell line (AA8) and three repair-deficient sublines of AA8 (EM9, UV4, and UV5) were used to study the nature of the cytotoxic lesions produced by the bioreductive alkylating agents mitomycin C and porfiromycin under aerobic and hypoxic conditions. The sensitivities of the repair-deficient sublines to the drugs varied markedly: EM9 was similar to AA8, whereas UV4 was exquisitely sensitive and UV5 was of intermediate sensitivity. Moreover, both the relative toxicities of the two drugs and the relative toxicities of each drug under aerobic and hypoxic conditions varied for the different cell lines. These data suggest that there are differences in the spectra of toxic lesions produced by mitomycin and porfiromycin and that there are differences in the lesions produced by these drugs under aerobic and hypoxic conditions.