Carcinogens enhance survival of UV-irradiated simian virus 40 in treated monkey kidney cells: induction of a recovery pathway?

Abstract

Treatment of [African green] monkey kidney cells with low doses of carcinogens enhances the survival of UV-irradiated SV-40. This is true for compounds with UV-like effects (metabolites of aflatoxin B1, N-acetoxyacetylaminofluorene) and compounds with X-ray-like effects (methyl methanesulfonate, ethyl methanesulfonate). This phenomenon resembles the UV-reactivation of viruses in eukaryotic cells. The carcinogen-induced enhancement of the survival of UV-irradiated SV-40 is correlated with the inhibition of host-cell DNA synthesis, suggesting that the inhibition is an inducing agent. An enhancement of UV-irradiated SV-40 survival is also obtained in cells treated with hydroxyurea or cycloheximide for long enough that there is still inhibition of host DNA synthesis during the early stage of SV-40 infection. Treatment of host cells with carcinogens apparently induces a new recovery pathway that facilitates the replication of damaged DNA, bypassing the lesions and resulting in the enhanced survival of UV-irradiated SV-40. This inducible process might represent the expression of SOS repair functions in eukaryotic cells analogous to the previously demonstrated induction of SOS repair in bacteria after UV or carcinogen treatment.