中文摘要：

目的研究候选基因GSTP1在胃癌细胞株中的表达及其启动子区的甲基化状态，初步探讨胃癌细胞株GSTP1基因表达水平与其启动子区甲基化的相关性。方法采用RT-PCR和Westernblot技术分别检测GSTPI在人胃癌细胞株MGC803、BGC823和SGC7901中的mRNA和蛋白表达水平。甲基化特异性PCR（MSP）法检测启动子区域甲基化状态。分别用不同浓度的去甲基化药物5-氮杂胞苷处理GSTP1基因启动子区高甲基化状态细胞后，再检测GSTP1基因蛋白表达水平。结果人胃癌细胞株BGC823和SGC7901中GSTP1mRNA和蛋白呈阳性表达，MGC803中mRNA和蛋白呈阴性表达；BGC823和SGC7901细胞GSTP1基因启动子区域未发生甲基化，而MGC803细胞启动子区呈高甲基化状态；经5-氮杂胞苷药物干预后，MGC803细胞的GSTP1蛋白表达明显增强。结论胃癌MGC803细胞株中GSTP1基因表达沉默与启动子区高甲基化状态有关。

英文摘要：

Objective To explore whether aben＇ant metbylation is a contribution factor to transcriptional inactivation of GSTP1 in gastric cancer cell lines via the investigation of the expression and methylation status of GSTP1 gene in human gastric cancer cell lines were investigated. Methods RT-PCR and Western-Blot method were used to explore mRNA and protein expression of the GSTP1 gene. Methylation specific PCR （MSP） was used to test promoter methylation of GSTPI gene in MGC803, BGC823 and SGC7901. The hypermethylation stares was reversed by adding various concentration of 5-aza-2＇-deoxycytidine （5-aza-dC）. Results GSTP1 gene and protein expression were obviously expressed in BGC823 and SGC7901 cell lines,both cell lines showed no methylation. On the contrary,loss of GSTP1 mRNA and protein expression was detected in MGC803 due to the methylation of CpG island of GSTPI gene. After the treatment of 5-aza-dC in hyper- methylafion cell line MGCS03, the levels of GSTP1 protein expressions were increased obviously. Conclusion This promoter hypemlethylation is correlated with GSTP1 gene expression in human gastric cancer MGC803 cell line and plays a key role in GSTP1 silencing.