乳腺癌组织及癌旁组织HER2基因CpG岛甲基化水平及其mRNA表达的研究

目的探讨乳腺癌组织及癌旁组织人类表皮生长因子受体2(HER2)基因CpG岛甲基化率和HER2mRNA表达的差异。方法收集经病理确诊的50份乳腺癌组织和对应的癌旁组织样本,采用焦磷酸测序法、实时聚合酶链反应(PCR)和免疫组化法分别检测HER2启动子CpG岛甲基化率、HER2 mRNA表达和HER2蛋白表达。结果HER2阳性乳腺癌组织HER2 mRNA相对表达量高于HER2阴性癌组织(P<0.05),但HER2启动子CpG岛甲基化率差异无统计学意义(P>0.05)。HER2阴性乳腺癌组织HER2基因启动子CpG岛甲基化率显著高于对应的癌旁组织(P<0.05),而HER2 mRNA表达则低于对应的癌旁组织(P<0.05)。HER2阳性的乳腺癌组织与其对应的癌旁组织之间以及HER2阳性与阴性癌旁组织之间,HER2基因启动子CpG岛甲基化率和HER2 mRNA相对表达量差异均无统计学意义(P>0.05)。结论在HER2阴性的乳腺癌癌旁组织中,HER2基因启动子CpG岛的低甲基化可能是HER2 mRNA高表达的机制之一。

Methylation level and mRNA expression of CpG island of HER2 gene in breast cancer and its adjacent tissues

Objective To investigate the methylation level and mRNA expression of CpG island of human epidermal growth factor receptor 2(HER2)gene in breast cancer and its adjacent tissues.Methods Totally,50 samples of breast cancer tissues and adjacent tissues confirmed by pathology were collected.The methylation rate of CpG island of HER2 promoter,the expression of HER2 mRNA and the expression of HER2 protein were determined by pyrosequencing,real-time polymerase chain reaction(PCR)and immunohistochemistry,respectively.Results The relative expression of HER2 mRNA in HER2 positive breast cancer tissues was higher than that in HER2 negative breast cancer tissues(P<0.05),and there was no statistical significance in the methylation rate of CpG island of HER2 promoter(P>0.05).The methylation rate of HER2 promoter CpG island in HER2 negative breast cancer tissues was higher than that in adjacent tissues(P<0.05),while the expression of HER2 mRNA was lower than that in adjacent tissues(P<0.05).There was no statistical significance in the methylation rate of CpG island of HER2 promoter and the expression of HER2 mRNA between HER2 positive breast cancer and adjacent tissues and between the 2 groups of adjacent tissues(P>0.05).Conclusions Hypomethylation of CpG island of HER2 promoter may be one of the mechanisms of high expression of HER2 mRNA in breast cancer adjacent tissues of HER2 negative group.