人胃癌组织中肝素酶基因启动子甲基化状态与肿瘤侵袭转移的关系

Methylation status of human heparanase promoter and its correlation with tumor invasion and metastasis in gastric cancer

目的探讨人胃癌组织中肝素酶（HPA）基因启动子的甲基化状态及其与HPA表达、肿瘤侵袭转移的关系。方法应用免疫组织化学、逆转录一聚合酶链反应（RT—PCR）方法检测48例胃癌组织标本及相应癌旁组织中HPA蛋白和mRNA表达；采用亚硫酸氢钠修饰、甲基化PCR（MSP）、甲基化克隆测序（BSP）法检测胃癌组织和癌旁组织中HPA基因启动子区域CpG岛甲基化状态，并探讨与胃癌临床病理特征的关系。结果胃癌组织中HPAmRNA和蛋白的阳性表达率分别为79．20％（38／48）、93．75％（45／48），显著高于癌旁组织（P〈0．05）。MSP、BSP检测发现13例胃癌组织HPA启动子CpG岛呈低甲基化状态，且其甲基化程度与HPA的表达及胃癌的分化程度、TNM分期、淋巴结转移、远处转移明显相关（P〈0．05）。结论HPA基因启动子区域CpG岛甲基化程度与HPA的表达及胃癌的发生、发展有关，在肿瘤侵袭、转移过程中起重要调节作用。

Objective To investigate the methylation status of CpG islands of heparanase （HPA） promoter and its correlation with HPA expression, tumor invasion and metastasis of human gastric cancer. Methods Immunohistochemistry and reverse transcription-polymerase chain reaction （RT-PCR） were applied to detect the expression of HPA in 48 gastric carcinomas and corresponding adjacent non-neoplastic tissues. The methylation status of CpG islands in HPA promoter was determined by hydrosulfite modification, MSP and BSP methods, and its correlation with the clinicopathological features of gastric carcinoma was analyzed. Results The positive expression rate of HPA mRNA and protein in gastric carcinomas was 79. 20% （38/48） and 93.75% （45/48）, respectively, which was significantly higher than that in adjacent non-neoplastic tissues. MSP and BSP revealed the hypomethylation in the CpG islands of HPA promoter in 13 cases of gastric carcinoma, which was significantly associated with the depth of differentiation, TNM stage, lymphatic and distant metastasis in gastric carcinoma （P 〈 0. 05 ）. Conclusion The methylation status of CpG islands of HPA promoter was correlated with the HPA expression and the development of gastric cancer, which may play an important role in the tumor invasion and metastasis.