摘要目的 探讨食管下段鳞癌和反流性食管炎组织中p16基因和hMLH1基因启动子区的甲基化状况,及与其临床病理特征之间的关系.方法 根据胃镜检查及病理学检查确诊正常食管上皮标本12例,食管下段鳞癌13例,反流性食管炎64例(其中基底细胞增生43例、不典型增生21例).提取各个组织的基因组DNA,用甲基化特异性聚合酶链反应法检测p16基因启动子区的甲基化状态;用亚硫酸氢钠-酶切法检测hMLH1基因启动子区的甲基化状态.用免疫组织化学SP法检测蛋白表达情况.结果 正常食管上皮、反流性食管炎中的基底细胞增生和不典型增生,以及食管下段鳞癌组织中p16基因启动子区甲基化率分别为:0/12、14.0%(6/43)、38.1%(8/21)、6/13;并且p16基因启动子区甲基化率随食管病变程度的进展呈逐渐升高趋势;p16蛋白在正常食管上皮组织中均正常表达,基底细胞增生、不典型增生和食管下段鳞癌组织中的阴性表达率分别为:25.6%(11/43)、76.2%(16/21)、11/13;在正常食管上皮和反流性食管炎组织里均未检测出hMLH1基因启动子区甲基化;在食管下段鳞癌组织中1例检测hMLH1基因启动子区甲基化.p16基因启动子区甲基化与蛋白阴性表达密切相关(P＜0.01),而hMLH1基因启动子区甲基化与蛋白表达无显著相关性(P=0.590).结论 p16基因动子区甲基化可能是食管下段鳞癌发生的早期分子事件之一;反流性食管炎的基底细胞增生可能与食管下段鳞癌相关;hMLH1基因启动子区甲基化可能不直接参与食管下段鳞癌的发生.

abstractsObjective To study the promoter methylation pattern of p16 and hMLH1 genes in esophageal squamous cell carcinoma and reflux esophagitis, and to correlate the results with clinical and pathologic findings. Methods Twelve cases of normal esophagus, 13 cases of esophageal squamous cell carcinoma, 43 cases of reflux esophagitis with basal cell hyperplasia and 21 cases of reflux esophagitis with dysplasia, as confirmed by endoscopic and pathologic examination, were enrolled into the study. Genomic DNA was extracted. The promoter methylation status of p16 was measured by methylation-specific polymerase chain reaction. The promoter methylation status of hMLH1 was measured by sodium bisulfite-restriction enzyme digestion. Immunohistochemical study for p16 and hMLH1 proteins was also carried out. Results The rates of p16 methylation in normal esophageal epithelium, basal cell hyperplasia, dysplasia and esophageal squamous cell carcinoma were 0/12, 14.0% (6/43), 38.1% (8/21) and 6/13, respectively.The p16 methylation correlated with the progress of esophageal lesions. On the other hand, the hMLH1 methylation was not observed in the normal esophageal epithelium and reflux esophagitis. One case of esophageal squamous cell carcinoma showed the presence of hMLH1 methylation. The hMLH1 promoter hypermethylation did not correlate with the clinical and pathologic features. Conclusions The p16 methylation may be one of the earliest events in the pathogenesis of esophageal squamous cell carcinoma and is also observed in reflux esophagitis. Reflux esophagitis may be related to the development of esophageal squamous cell carcinoma in Chinese population. In contrast, hMLH1 methylation may not be directly involved in the tumorigenesis of esophageal squamous cell carcinoma.