Sudo Makoto, Chong Ja-Mun, Sakuma Kazuya, Ushiku Tetsuo, Uozaki Hiroshi, Nagai Hideo, Funata Nobuaki, Matsumoto Yoshiro, Fukayama Masashi
Department of Pathology, Graduate School of Medicine, University of Tokyo, Hongo, Tokyo, Japan.
Int J Cancer. 2004 Mar 20;109(2):194-9. doi: 10.1002/ijc.11701.
Promoter hypermethylation of various tumor-related genes is extremely frequent in Epstein-Barr virus (EBV)-associated gastric carcinoma (EBVaGC). To investigate the significance of the promoter methylation in EBVaGC, we focused on one of the important proteins in the carcinogenesis of the stomach, E-cadherin. Methylation-specific PCR analysis (MSP) was applied to surgically resected gastric carcinomas, together with immunohistochemistry, PCR-based analysis of mutations and allelic loss, and site-specific MSP of E-cadherin gene. By MSP, nearly all of the carcinomas showed aberrant methylation of E-cadherin promoter in EBVaGC (21/22), and the frequency of this aberration was significantly higher than that in EBV-negative gastric carcinoma (GC; 45/81; p = 0.0003). According to immunohistochemistry of E-cadherin, the frequency of abnormal staining pattern in EBVaGC (87%) was comparable to that in the diffuse type (80%), but higher than that in the intestinal type of EBV-negative GC (47%). Promoter methylation was well correlated with abnormal staining pattern in EBVaGC, but not in EBV-negative GC. Neither mutation nor allelic loss of E-cadherin was observed in EBVaGC. Methylation status of E-cadherin within each carcinoma was heterogeneous as far as examined. Thus, in addition to the known association involving p16, we determined that promoter methylation-mediated silencing of E-cadherin gene was also closely associated with the development of EBVaGC, although it becomes heterogeneous within a given tumor along its progression.
在爱泼斯坦-巴尔病毒（EBV）相关的胃癌（EBVaGC）中，各种肿瘤相关基因的启动子高甲基化极为常见。为了研究启动子甲基化在EBVaGC中的意义，我们聚焦于胃癌发生过程中的一种重要蛋白质——E-钙黏蛋白。甲基化特异性PCR分析（MSP）应用于手术切除的胃癌组织，同时结合免疫组织化学、基于PCR的突变和等位基因缺失分析以及E-钙黏蛋白基因的位点特异性MSP。通过MSP分析，几乎所有EBVaGC中的癌组织（21/22）都显示出E-钙黏蛋白启动子的异常甲基化，这种异常的频率显著高于EBV阴性胃癌（GC；45/81；p = 0.0003）。根据E-钙黏蛋白的免疫组织化学分析，EBVaGC中异常染色模式的频率（87%）与弥漫型（80%）相当，但高于EBV阴性GC的肠型（47%）。在EBVaGC中，启动子甲基化与异常染色模式密切相关，但在EBV阴性GC中并非如此。在EBVaGC中未观察到E-钙黏蛋白的突变或等位基因缺失。就所检测的情况而言，每个癌组织内E-钙黏蛋白的甲基化状态是异质性的。因此，除了已知的与p16相关的关联外，我们确定E-钙黏蛋白基因的启动子甲基化介导的沉默也与EBVaGC的发生密切相关，尽管在给定肿瘤的进展过程中其会变得异质性。
