中文摘要：

目的探讨去乙酰化转移酶抑制剂TSA对人肝癌SMMC-7721细胞株E-cadherin基因（E-cad）启动子区甲基化及其表达的影响。方法TSA（300nm／L）处理人肝癌SMMC-7721细胞，MTT法、TUNEL染色法分别检测细胞生长抑制及凋亡情况，甲基化特异性的PCR（methylation-specific PCR，MSP）检测处理前后E-cad启动子区CpG岛甲基化状态；Western blot检测处理前后E-cad及DNMT3b表达水平的变化。结果TSA能抑制人肝癌SMMC-7721细胞生长并诱导其发生凋亡，与对照组相比，实验组细胞生长抑制率为21.85％，对照组细胞凋亡率为（4.69±0.56）％，实验组凋亡率为（14.94±0.91）％，与对照组相比，凋亡细胞明显增多（P=0.000）。用药前E-cad启动子区CpG岛为甲基化状态，E-cad蛋白表达阴性。TSA处理后E-cad启动子区CpG岛发生脱甲基化，E-cad蛋白恢复表达。TSA亦导致DNMT3b的表达水平降低。结论去乙酰化转移酶抑制剂TSA能抑制人肝癌SMMC-7721细胞生长，并可诱导其发生凋亡，逆转E-cad基因启动子区的甲基化状态，并恢复该基因表达。TSA有可能通过DNMT3b发挥脱甲基化作用。

英文摘要：

Objective To study the effects of histone deacertylase inhibitor （TSA） on promoter methylation and expression of E-cadherin gene in a hepatocellular carcinoma cell line SMMC7721. Methods Hepatocellular carcinoma cell line SMMC-7721 was treated with TSA（300nm/L）, MTT method was used to investigate the growth inhibition ratio, TUNNL was conducted to measure the apoptosis ratio, methylation-specific PCR（MSP） was employed to detect changes in the CpG island methylation of E-cad promoter region, Western blot technique was used to detect the expression of E-cad gene and DNMT3b before and after TSA treatment, respectively. Results TSA decreases the SMMC-7721 cell viability and induces apoptosis, the growth inhibition ratio was 21.85% compared with control group. The apoptosis ratio of control group was （4.69±0.56）%, the apoptosis ratio of TSA treatment group was（14.94±0.91）%. The apoptosis ratio of TSA treatment group was significantly higher than that of control group （P=0.000）. Before treated with TSA, the CpG island of E-cad promoter region was methylated, and the expression of E-cad was negative. TSA treatment induces demethylation of the CpG island in E-cad promoter region, causes the re-expression of E-cad. TSA reduces the expression of DNMT3b. Conclusions TSA decreases the SMMC-7721 cell viability and induces apoptosis, reverses the methylation status of E-cad promoter region, and resumes E-cad gene expression. TSA may induce demethylation through down-regulating the expression of DNMT3b.