食管鳞癌中hMLH1、E-cadherin、p16^INK4a基因启动子甲基化及其意义  

Promoter methylation and its significance of hMLH1, E-cadherin and p16^(INK4a) gene in esophageal squamous cell carcinoma

作　　者：缪珑昇[1] 相加庆[1] 张亚伟[1] 黄丹[2] 沈镇宙[1] 

机构地区：[1]复旦大学附属肿瘤医院胸外科 复旦大学上海医学院肿瘤学系,上海200032 [2]学附属肿瘤医院病理科 复旦大学上海医学院肿瘤学系,上海200032

出　　处：《中国癌症杂志》2009年第5期340-346,共7页China Oncology

摘　　要：背景与目的:目前认为抑癌基因启动子甲基化导致转录抑制是恶性肿瘤发生的重要机制之一,hMLH1、E-cadherin及p16INK4a基因在多种恶性肿瘤中都已被证实存在较高频率的甲基化。本研究通过检测食管鳞癌组织及癌旁组织中hMLH1、E-cadherin、p16INK4a基因启动子甲基化的发生情况,探讨hMLH1、E-cadherin、p16INK4a基因启动子甲基化在食管鳞癌发生发展中的作用。方法:采用酚-氯仿法提取105例食管鳞癌组织及癌旁组织的基因组DNA,应用甲基化特异性PCR对所提DNA进行hMLH1、E-cadherin、p16INK4a基因甲基化检测。采用EnVison免疫组织化学二步法对癌组织中上述3种基因蛋白表达进行检测。结果:癌组织中E-cadherin、hMLH1、p16INK4a基因启动子甲基化的阳性率分别为57.1%(60/105)、20.9%(22/105)和50.5%(53/105),而癌旁食管组织中相应的3个基因的甲基化率分别为10.5%(11/105)、1.9%(2/105)和7.6%(8/105),均显著低于癌组织。E-cadherin(P=0.021)及p16INK4a(P=0.026)基因甲基化与蛋白表达缺失密切相关,而hMLH1基因甲基化与蛋白表达无显著相关性。E-cadherin基因启动子甲基化与淋巴结转移有关(P=0.016),p16INK4a基因启动子甲基化与低分化癌有关性(P=0.024)。hMLH1基因甲基化与各项临床病理特征均无关。结论:食管鳞癌中p16INK4a基因启动子甲基化与相应蛋白表达缺失密切相关,且在低分化癌中更多见;E-cadherin基因启动子甲基化与相应蛋白质表达缺失有相关性,并且有淋巴结转移多见的显著特征,这2个基因的甲基化位点与食管鳞癌密切相关。hMLH1基因甲基化可能并不直接参与食管鳞癌的发生、发展。Background and purpose： Transcriptional silencing by promoter methylation is now believed to be an important mechanism of carcinogenesis. High frequency of promoter methylation of hMLH1, E-cadherin, and p16^INK4a gene is detected in various tumours. This study was to detect the methylation pattern of hMLH1, E-cadherin and p16^INK4a gene in esophageal squamous cell carcinoma and explore the role of these epigenetic changes in tumorigenesis. Methods： The frozen tumor specimens and matched normal mucosal tissue specimens from 105 patients with esophageal squamous carcinoma were used for the extraction of DNA by phenol-chloroform method. Methylation changes in the promoter region of hMLH1,E-cadherin, and p16^INK4a genes were determined by using methylation-specific PCR （MSP）. Immunohistochemical staining of hMLHI, E-cadherin, and p16^INK4a protein was performed by using EnVision two-step method in the tumor tissues. Results： The positive rates of genes promoter hypermethylation of E-cadherin, hMLH1, and p16^INK4a were 57.1% （60/105）, 20.9% （22/105） and 50.5% （53/105） in tumor tissues, as compared to 10.5% （11/105）, 1.9% （2/105） and 7.6% （8/105） in normal mucosal tissue, respectively. The positive rates were significantly higher in tumor tissues than in normal mucosal tissue for each of the three genes. The absence rates of protein expression of E-cadherin, hMLH1, andp 16^INK4a were 48.6% （51/105）, 21.9% （23/105） and 71.4% （75/105） respectively. Promoter hypermethylation of E-cadherin （P=0.021） or p16^INK4a （P=-0.026） gene was remarkably associated with the loss of protein, hMLH 1 promoter hypermethylation was not significantly correlated with the loss of protein. ESCC with E-cadherin gene promoter hypermethylation was significantly correlated with lymph node metastasis （P=0.01 6）, p 16^INK4a gene promoter hypermethylation was found more in poorly-differentiated squamous cell carcinoma （P--0.024）, hMLHI promoter hypermethylation was not associated with any

关 键 词：食管肿瘤 癌 鳞状细胞 启动子 甲基化hMLH1基因 E-CADHERIN基因 p16INK4a基因 

分 类 号：R735.1[医药卫生—肿瘤] R730.43[医药卫生—临床医学]