大鼠肝癌变中p53点突变及其蛋白表达的研究

Study on expression of mutant P53 protein and point mutation in exon 6 of p53 gene during hepatocarcinogenesis in rats

目的 研究大鼠肝癌变中突变型Ｐ５３蛋白（ｍＰ５３）的表达及 ｐ５３基因第６外显子点突变。方法 通过ＤＥＮ诱发的启动模型和肝癌模型，应用免疫组化、ＭＤＴ－ＰＣＲ－ＳＳＣＰ和直接测序技术分别研究ｍＰ５３表达和 ｐ５３基因第６外显子点突变。结果 ｍＰ５３阳性细胞仅见于癌前个别肝细胞增生结节中，８／１８例（４４．４４％）肝细胞癌呈ｍＰ５３阳性；８例ｍＰ５３阳性肝癌中仅有１例（１２．５０％）被检出ｐ５３基因第６外显子发生点突变，即第２０８位密码子第１碱基Ｃ—Ｇ颠换。结论 在 ＤＥＮ诱发的启动模型和肝癌模型中 ｐ５３基因突变可发生于大鼠肝癌变之癌前及肝癌形成阶段，且第６外显子突变率低。

Objective To study the expression of mutant P53 protein(mP53) and point mutation in exon 6 of p53 gene during hepatocarcino- genesis in rats. Methods By using immunohistochemical fechnique, MDT-PCR-SSCP and direct sequencing the mP53 expression and point muta- tion in exon 6 of p53 gene in both Solt-Farber model and DEN-induced liver cancer model were detected. Results The mP53 was detectable in a few preneoplastic nodules and 8 of 18 rats with hepatocellular carcinomas(HCC) (44.44% ). Only 1 of 8 HCCs mP53 positive reactivity with a C- G transversion was found. The mutation sat on the fist base of 208th codon. Conclusion p53 gene mutation could occur in precancerous stage as well as in HCC with a low frequency in both Solt-Farber model and DEN-induced liver cancer model.