中文摘要：

目的：研究雷公藤内酯醇（triptolide,TP）对人肝癌SMMC-7721细胞增殖的影响以及对P53基因的去甲基化作用。方法：MTT法检测TP对SMMC-7721细胞增殖的影响,甲基特异性PCR检测TP对SMMC-7721细胞P53基因甲基化的影响,RT-PCR检测SMMC-7721细胞甲基转移酶DNMT1、DNMT3a、DNMT3bmRNA的表达,Western blotting检测SMMC-7721细胞中P53蛋白的表达。结果：TP剂量依赖性抑制SMMC-7721细胞的增殖（P〈0.05）,40 ng/ml时的抑制率达（73.5±3.02）%,其半数抑制浓度（IC50）约为20 ng/ml。TP显著抑制SMMC-7721细胞中DNMT1、DNMT3a、DNMT3bmRNA的表达（P〈0.05,P〈0.01）;TP作用后P53基因的高甲基化被逆转,并呈剂量依赖性;TP可显著增强SMMC-7721细胞中P53蛋白的表达。结论：TP可通过抑制甲基转移酶使P53基因去甲基化,促进P53蛋白的表达,从而抑制SMMC-7721细胞的增殖。

英文摘要：

Objective： To study the effect of triptolide（TP） on the proliferation of hepatocarcinoma SMMC-7721 cells and its effect on demethylation of P53 gene.Methods： The effect of TP on proliferation of SMMC-7721 cells was measured by MTT method,the effect of TP on P53 gene methylation in SMMC-7721 cells was analyzed by methylation specific PCR,the expressions of methyltransferase DNMT1,DNMT3a and DNMT3b mRNA in SMMC-7721 cells were measured by RT-PCR,and the protein expression of P53 in SMMC-7721 cells was detected by Western blotting assay.Results： TP inhibited the proliferation of SMMC-7721 cells in a dose-dependent manner（P〈0.05）,with the inhibitory rate being（73.5±3.02）% at 40 ng/ml TP,and IC50 of TP was 20 ng/ml.TP significantly inhibited DNMT1,DNMT3a,and DNMT3b mRNA expressions in SMMC-7721 cells（P〈0.05,P〈0.01）,and dose-dependently reversed the hypermethylation of P53 gene and enhanced P53 protein expression in SMMC-7721 cells.Conclusion： TP can inhibit the proliferation of SMMC-7721 cells through the inhibiting methyltransferase expression,which augment the demethylation of P53 gene and results in the increased expression of P53 protein.