EFFECT OF GREEN TEA ON P53 MUTATION DISTRIBUTION IN ULTRAVIOLET-B RADIATION-INDUCED MOUSE SKIN TUMORS

In the present study, administration of green tea to SKH-1 mice, via t he drinking fluid, was found to significantly reduce the incidence and volume of ultraviolet B (UVB) radiation-induced skin tumors. Thirty-s ix skin tumors induced by UVB and 32 skin tumors induced by UVB, in mi ce treated with green tea in their drinking water, were collected and examined for the presence of mutations in the p53 gene, Polymerase cha in reaction products from p53 exons 5-8 were screened by single-strand conformation polymorphism and direct sequence analyses. Eight of 36 U VB-induced tumors contained nine p53 mutations, with four in exon 5 an d five in exon 8, In contrast, nine of 32 UVB-induced tumors in mice t reated with green tea contained 11 p53 mutations, with two in exon 5, five in exon 6 and four in exon 8, All of the p53 mutations occurred a t dipyrimidine sequences. These results were further corroborated by p 53 immunohistochemistry. The most frequent mutations were C-->T or T-- >C transitions, which are consistent with the genetic alterations caus ed by UVB exposure, Interestingly, mutations found in exon 6 of the p5 3 gene occurred only in tumors from the UVB/green tea group. Thus, the tumors observed in UVB/green-tea-treated mice have a different exon d istribution of p53 mutations than tumors obtained from mice treated wi th UVB alone.