鼻咽癌组织、细胞及患者外周血E-钙黏蛋白基因启动子的异常甲基化

Aberrant methylation around E-cadherin gene promoter region in nasopharyngeal carcinoma tissues and cell lines,and the peripheral blood of patients

目的探讨鼻咽癌组织和细胞E-钙黏蛋白(E-cadherin)基因表达水平与启动子甲基化的相关性,以及患者外周血E-cadherin甲基化作为肿瘤分子标志物的可能。方法采用RT-PCR检测鼻咽癌组织及两种鼻咽癌细胞株HNE1和CNE2中E-cadherin表达水平,以甲基化特异性PCR及硫化测序方法甲基化状态分析鼻咽癌组织、两种鼻咽癌细胞株及鼻咽癌患者外周血中E-cadherin启动子区域的甲基化状态。结果 40例鼻咽癌组织中E-cadherin表达下调率为80%(32/40),甲基化率为65%(26/40),5例正常鼻咽组织中未检测到E-cadherin甲基化,鼻咽癌患者外周血中E-cadherin甲基化率为45%(9/20)。结论基因启动子区域高甲基化状态可能是导致鼻咽癌组织中E-cadherin表达下调的重要机制,经外周血检测E-cadherin甲基化将为鼻咽癌的筛查诊断提供敏感、特异的无创检测方法。

Objective To investigate the expression and methylation status of E - cadherin in nasopharyngeal car- o;noma （NPC）, and to evaluate efficacy of methylated E -cadherin in peripheral blood as a potential biomarker on the di- agnosis of NPC, Methods RT - PCR and methylation - specific PCR （MSP） were performed to analyze the mRNA ex- pression levels and methylation status of E - cadherin in primary NPC specimens and two tumor cell lines. MSP was also used to observe the methylated E - cadherin in primary NPC specimens, two tumor cell lines and peripheral blood samples of NPC patients. Results Down - regulated E - cadherin expression was detected in 32 of 40 （80%） primary tumors as well as two NPC cell lines, when compared with normal tissues. Methylated E - cadherin was observed in 26 of 40 （65%） primary tumors but not in normal tissues. Moreover, E - cadherin methylation was also detected in 9 of 20 （45%） periph- eral blood samples of NPC patients. Conclusion Promoter methylation may be one of the mechanisms inducing E - cad- herin silencing. Detection of methylated E - cadherin in peripheral blood suggests potential clinical application for nonin- vasive diagnosis and disease monitoring of NPC.