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 |
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Authors: | Y Fujiwara Y Kano M Tatsumi P Paul |
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Institution: | Department of Radiation Biophysics, Kobe University School of Medicine, Kusunoki-cho 7-12, Ikuta-ku, Kobe 650 Japan |
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Abstract: | The effects of a tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) and/or an anti-promotor 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 co- operation. Thus, the results conceivably imply that the 6TGr-recessive mutation expression, but not fixation, can be modulated at the cell level by the 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. |
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