SRY-box 17基因在食管鳞状细胞癌中异常甲基化及表达的研究

目的:检测食管磷癌(esophageal squamous cell cancer,ESCC)细胞株及组织标本中Wnt通路相关因子SRY-box 17基因的甲基化状态及表达情况,探讨其与食管鳞癌发生的相关性.方法:分别采用甲基化特异性-PCR(methylation specific-PCR,MSP)和RT-PCR的方法检测食管癌细胞株TE1、TE13及109例食管鳞癌及相应癌旁非肿瘤组织中SRY-box 17基因的甲基化状态及mRNA表达情况,并分析其与Wnit通路中心因子β-catenin蛋白表达的关系.结果:在食管癌细胞株TE1和TE13中,SRY-box 17基因mRNA均呈阴性或弱阳性表达,用甲基化抑制剂5-氮-2’-脱氧胞苷(5-aza-2’-deoxycytidine,5-Aza-dC)处理后,其mRNA全部恢复阳性表达；MSP检测结果显示,在食管癌细胞株中SRY-box 17基因均呈高甲基化状态；在食管癌组织标本中,SRY-box17基因的甲基率为89.0％ (97/109),明显高于癌旁组织的53.2％ (58/109)(P＜0.01)；癌组织中SRY-box 17基因的甲基化率在Ⅲ和Ⅳ期肿瘤患者中明显高于Ⅰ和Ⅱ期患者(P＜0.05),而该基因的甲基化率与肿瘤患者的组织学分级无相关性；在癌组织中该SRY-box17mRNA的阳性表达率为28.4％(31/109),明显低于癌旁组织(P＜0.01).其mRNA表达的缺失率及通路中心因子β-catenin蛋白的异质表达率均与该基因的甲基化状态有相关性(P＜0.05).结论:食管鳞癌组织及细胞株中SRY-box 17基因均呈高甲基化状态,该基因的高甲基化可能是引起mRNA表达下调的重要机制之一,并可能通过Wnt/β-catenin信号转导通路的激活在食管癌的发生、发展中具有重要作用；对该基因的甲基化检测可能对食管癌的预后判断有一定的临床指导意义.

Hypermethylation and aberrant expression of SRY-box17 gene in esophageal squamous cell cancer

Objective: To investigate the methylation status of SRY-box17 gene in Wnt signaling pathway in esophageal squamous cell carcinoma (ESCC) cell lines and ESCC tissues, and to explore the association between SRY-box17 gene and the pathogenesis of ESCC. Methods: The methylation of SRY-box17 gene and its mRNA expression in ESCC cell lines TE1 and TE13 as well as ESCC tissues and their adjacent tissues from 109 patients were detected by methylation specific-PCR (MSP) and RT-PCR, respectively. The association of SRY-box17 gene with β-catenin in Wnt signaling pathway was analyzed. Results: The expression of SRY-box17 mRNA was undetected or at extremely low level in ESCC cell lines TE1 and TE13. The expression level of SRY-box17 mRNA was obviously increased after treatment with a demethylation agent 5-aza-2’-deoxycytidine (5-Aza-dC). The result of MSP indicated that the SRY-box17 gene exerted a hypermethylation status in ESCC cell lines TE1 and TE13. The methylation rate of SRY-box17 gene was 89.0% (97/109) in the ESCC tissues, which was significantly higher than that in the adjacent tissues [53.2% (58/109); P<0.01]. The methylation rates of SRY-box17 gene for clinical stage Ⅲ-Ⅳ was significantly higher than that for clinical stage Ⅰ-Ⅱ (P < 0.05), but the methylation rate was not associated with the histologic grade (P > 0.05). Furthermore, the positive rate of SRY-box17 mRNA expression [28.4% (31/109)] in the ESCC tissues was significantly lower than that in the adjacent tissues. The hypermethylation status of SRY-box17 gene was associated with the loss of SRY-box17 mRNA expression and the ectopic expression of β-catenin (P < 0.05). Conclusion: The hypermethylation of SRY-box17 gene is a frequent event in ESCC cell lines and the ESCC tissues, and it may play an important role in the downregulation of SRY-box17 mRNA expression and the pathogenesis and development of ESCC through the activation of Wnt/β-catenin signaling pathway. Analysis of methylation status of SRY-box17 gene may have definite value in predicting the prognosis of ESCC.