SUPPRESSION OF UV-INDUCED MUTATIONS BY WILD-TYPE P53 PROTEIN IN HUMANOSTEOSARCOMA CELLS

We have examined whether the tumour suppressor p53 protein suppressed UV-induced mutations in the hypoxathine-guanine phosphoribosyl transfe rase (HPRT) gene and in the supF gene of the shuttle vector plasmid pM Y189, We used human osteosarcoma Saos-LP12 cells, in which wild type ( wt) p53 protein was induced by treatment with isopopyl-beta-D-thiogala ctopyranoside. The induction of wt p53 protein suppressed UV-induced m utations but not spontaneous mutations in the HPRT gene, The frequency of UV-induced mutations induced by UV-irradiation of the plasmid was also significantly lower in cells with induced wt p53 protein than in the uninduced cells, In addition, we found that frequency of G : C to A : T transition mutations which occurred at the 3' base pair of dipyr imidine sites were significantly lower in the cells with induced wt p5 3 protein than in the uninduced cells, These findings suggest that wt p53 protein may play roles in modulating DNA repair pathway, resulting in the suppression of UV-induced mutations.