Solar and UVC-induced mutation in human cells and inhibition by deoxynucleosides.
Optimum conditions were established for quantitating the induction of hypoxanthine guanine phosphoribosyl transferase-deficient (HGPRT-) mutants in HeLa cells and in a human amelanotic melanoma cell line (MM96L). Compared at a fluence of equal toxicity (D37, fluence required to decrease cell survival to 37% of unirradiated control), noon sunlight in summer was slightly more mutagenic in MM96L than in HeLa cells (17 and 12 HGPRT- mutants per 10(6) survivors respectively). UVC (predominantly 254 nm) exhibited similar mutagenicity as equitoxic sunlight in HeLa but was 8-fold more effective in MM96L than equitoxic sunlight. Addition of a mixture of deoxyguanosine (20 microM), deoxyadenosine (20 microM), deoxycytidine (100 microM) and thymidine (20 microM) to the culture medium during the 7-day expression period following irradiation gave a 3-fold reduction in the UVC-induced mutation frequency of MM96L but not HeLa cells. The results suggest that these melanocytic cells are highly susceptible to mutagenesis by short wavelength UV, in a mechanism sensitive to deoxynucleosides.
Queensland Institute of Medical Research, Herston, Australia.
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D004249:DNA Damage; D003853:Deoxyribonucleosides / Q000494:pharmacology*; D006367:HeLa Cells / Q000528:radiation effects*; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics; D008544:Melanocytes / Q000528:radiation effects*; D008545:Melanoma / Q000473:pathology; D009152:Mutagenicity Tests; D011836:Radiation Tolerance; D013472:Sunlight; D014407:Tumor Cells, Cultured / Q000528:radiation effects; D014466:Ultraviolet Rays
D003853:Deoxyribonucleosides; D007041:Hypoxanthine Phosphoribosyltransferase