Lack of Direct Involvement of 8-Hydroxy-2'-deoxyguanosine in Hypoxanthine-guanine Phosphoribosyltransferase Mutagenesis in V79 Cells Treated with N,N'-Bis(2-hydroxyperoxy-2-methoxyethyl)-l,4,5,8-naphthalenetetracarboxylic-diimide (NP-III) or Riboflavin

The object of this study is to investigate the relationship between a typical product of oxidative DNA damage, 8-hydroxy-2'-deoxyguanosine (8OHdG), and mutagenesis in V79 cells through a molecular analysis of hypoxanthine-guanine phosphoribosyltransferase ( hprt ) gene mutants. We performed a direct sequencing analysis of the cDNA of mutants obtained after treatment with N,N'-bis(2-hydroxyperoxy-2-methoxyethyl)-l,4,5,8-naphthalenetetracarboxylic-diimide (NP-III) or riboflavin, each of which induces the formation of 8OHdG in cellular DNA upon UVA irradiation. The frequency of mutation after both treatments was no more than 2 to 5 times the control value. A considerable number of the mutants could not be amplified by RT-PCR, and this was also the case for the control mutants. Among the mutants analyzed, deletions and a TA→Ã transversion occurred predominantly. The reasons for the weak association of induction of 8OHdG with frequency of mutation and the possible mechanism of oxidative-stress-derived mutagenesis are discussed.