Liu Q, Wang Y, Crist K A, Wang Z Y, Lou Y R, Huang M T, Conney A H, You M
Department of Pathology, Medical College of Ohio, Toledo 43614, USA.
Carcinogenesis. 1998 Jul;19(7):1257-62. doi: 10.1093/carcin/19.7.1257.
In the present study, administration of green tea to SKH-1 mice, via the drinking fluid, was found to significantly reduce the incidence and volume of ultraviolet B (UVB) radiation-induced skin tumors. Thirty-six skin tumors induced by UVB and 32 skin tumors induced by UVB, in mice treated with green tea in their drinking water, were collected and examined for the presence of mutations in the p53 gene. Polymerase chain reaction products from p53 exons 5-8 were screened by single-strand conformation polymorphism and direct sequence analyses. Eight of 36 UVB-induced tumors contained nine p53 mutations, with four in exon 5 and five in exon 8. In contrast, nine of 32 UVB-induced tumors in mice treated 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 at dipyrimidine sequences. These results were further corroborated by p53 immunohistochemistry. The most frequent mutations were C-->T or T-->C transitions, which are consistent with the genetic alterations caused by UVB exposure. Interestingly, mutations found in exon 6 of the p53 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 distribution of p53 mutations than tumors obtained from mice treated with UVB alone.
在本研究中，通过饮用水给SKH - 1小鼠施用绿茶，发现可显著降低紫外线B（UVB）辐射诱导的皮肤肿瘤的发生率和体积。收集了36个由UVB诱导的皮肤肿瘤以及在饮用水中添加绿茶处理的小鼠中32个由UVB诱导的皮肤肿瘤，并检测p53基因中的突变情况。通过单链构象多态性和直接序列分析筛选p53外显子5 - 8的聚合酶链反应产物。36个UVB诱导的肿瘤中有8个含有9个p53突变，其中外显子5中有4个，外显子8中有5个。相比之下，在饮用绿茶处理的小鼠中，32个UVB诱导的肿瘤中有9个含有11个p53突变，其中外显子5中有2个，外显子6中有5个，外显子8中有4个。所有p53突变均发生在二嘧啶序列处。这些结果通过p53免疫组织化学得到进一步证实。最常见的突变是C→T或T→C转换，这与UVB暴露引起的基因改变一致。有趣的是，p53基因外显子6中发现的突变仅出现在UVB/绿茶组的肿瘤中。因此，与仅用UVB处理的小鼠相比，UVB/绿茶处理的小鼠中观察到的肿瘤具有不同的p53突变外显子分布。
