title: Effects of a tumor promoter and an anti-promoter on spontaneous and UV-induced 6-thioguanine-resistant mutations and sister-chromatid exchanges in V79 Chinese hamster cells.
abstract: The effects of a tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) and/or an anti-promoter antipain (protease inhibitor) on spontaneous and ultraviolet-induced sister-chromatid exchanges (SCEs) and 6-thioguanine-resistant (6TGr) recessive mutations were examined in V79 Chinese hamster cells in culture. TPA and/or antipain neither significantly altered base-line and UV-induced immediate SCE frequencies, nor decreased the level of delayed SCEs which persisted 6-7 days after irradiation. TPA and/or antipain appeared to enhance the recovery of UV-induced 6TGr colonies at the plateau expression phase despite non-mutagenicity by themselves and unaltered metabolic cooperation. Thus, the results conceivably imply that the 6TGr-recessive mutation expression, but not fixation, can be modulated at the cell level by TPA and/or antipain. Our results, together with the recent results of Loveday and Latt, may argue against the notion that TPA enhances the antipain-suppressible SCEs as an index of mitotic recombination in relevance with a tumor-promotion mechanism.
mesh_terms: D000818:Animals; D000976:Antipain / Q000494:pharmacology*; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D003434:Crossing Over, Genetic / Q000187:drug effects*; D009154:Mutation; D009842:Oligopeptides / Q000494:pharmacology*; D010704:Phorbols / Q000494:pharmacology*; D012854:Sister Chromatid Exchange / Q000187:drug effects* / Q000528:radiation effects; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D013866:Thioguanine / Q000494:pharmacology; D014466:Ultraviolet Rays
chemical_list: D009842:Oligopeptides; D010704:Phorbols; D000976:Antipain; D013866:Thioguanine; D013755:Tetradecanoylphorbol Acetate