食管鳞状细胞癌中Apaf-1基因启动子区甲基化状态及其与EZH2蛋白表达的关系

Promoter Methylation and Protein Expression of Apoptosis Protease Activating Factor-1 Gene in Esophageal Squamous Cell Carcinoma

目的探讨食管鳞状细胞癌(ESCC)中凋亡蛋白酶活化因子-1(Apaf-1)启动子区的甲基化状态及其与EZH2蛋白表达之间的相关性。方法应用甲基化特异性PCR(MSP)方法检测128例食管鳞癌患者癌灶组织及相应癌旁组织的Apaf-1基因甲基化情况,应用免疫组织化学方法检测Apaf-1和EZH2的蛋白表达情况。结果 Apaf-1基因在食管鳞癌组织中的甲基化率为52.3%,显著高于癌旁正常组织的4.7%(P<0.01),不同肿瘤TNM分期患者的Apaf-1基因甲基化率差异有统计学意义(P<0.01)。食管鳞癌组织Apaf-1蛋白表达阳性率为41.4%,显著低于相应癌旁正常组织的94.5%(P<0.01)。食管鳞癌组织EZH2蛋白表达阳性率为72.7%,显著高于相应癌旁正常组织的12.5%(P<0.01),不同肿瘤TNM分期和组织分化程度患者的Apaf-1和EZH2蛋白阳性表达率差异有统计学意义(P<0.01)。食管鳞癌中Apaf-1基因甲基化与其蛋白阳性表达率呈负相关(r=-0.722),Apaf-1与EZH2的蛋白表达呈明显的负相关(r=-0.232)。结论 Apaf-1和EZH2可能共同参与了食管鳞癌的发生发展,Apaf-1基因启动子区的异常高甲基化可能是食管鳞癌中此基因失活的重要原因之一。

Objective To investigate the promoter methylation of apoptosis protease activating factor-1 （Apaf-1） and its association with the protein expression of enhancer of zeste homolog 2 （EZH2） in esophageal squamous cell carcinoma （ESCC）. Methods The methylation-specific PCR （MSP） method was used to examine the methylation status of Apaf-1 in 128 ESCC patients, and immunohistochemistry method was used to detect the protein expression of Apaf-1 and EZH2 in tu- mors and corresponding normal tissues. Results The frequencies of Apaf-1 methylation in ESCC tumor tissues （52.3%, 67/ 128） were significantly higher than those in normal tissues （4.7%, 6/128） （P 〈 0.01）, which was associated with TNM stage. The positive protein expression of Apaf-1 was significantly decreased in ESCC tumor tissues （41.4%, 53/128） compared with that of paired normal tissues （94.5%, 21/128） （P 〈 0.01）. The positive protein expression of EZH2 was significantly increased in ESCC tumor tissues （72.7%, 93/128） than that of paired normal tissues （12.5%, 16/128） （P 〈 0.01）. The protein expressions of Apaf-1 and EZH2 were associated with the TNM stage and pathological differentiation in ESCC patients （P 〈 0.01）. The methylation status of Apaf-1 in ESCC was negatively correlated with the positive protein expression. The protein expressions of Apaf-1 and EZH2 were negatively correlated in ESCC. Conclusion Promoter hypermethylation of Apaf-1 and the higher protein expression of EZH2 may play important role in esophageal squamous cell carcinoma.