Blood Transfusion Center, Botucatu Medical School, UNESP - Sao Paulo State University, Distrito de Rubião Júnior, s/n, 18618-970 Botucatu-SP, Brazil.
World J Gastroenterol. 2010 Jan 21;16(3):312-9. doi: 10.3748/wjg.v16.i3.312.
To verify the methylation status of CDH1, DAPK, COX2, hMLH1 and CDKN2A genes and to evaluate their association with Helicobacter pylori (H. pylori)-cagA(+) and Epstein Barr virus (EBV) infections in gastric adenocarcinomas.
Methylation-specific PCR (MSP) assay was performed in 89 primary gastric carcinomas (intestinal and diffuse types). Microsatellite instability (MSI) analysis was performed using the BAT26 primer set and PCR products were analyzed with the ABI PRISM 3100 Genetic Analyzer using Genescan 3.7 software (Applied Biosystems). Detection of H. pylori and genotyping were performed by PCR, using specific primers for ureaseC and cagA genes. The presence of EBV was assessed by in situ hybridization. Statistical analyses were performed using the chi(2) or Fisher's exact test.
The most frequent hypermethylated gene was COX-2 (63.5%) followed by DAPK (55.7%), CDH1 (51%), CDKN2A (36%) and hMLH1 (30.3%). Intestinal and diffuse adenocarcinomas showed different methylation profiles and there was an association between methylation of E-CDH1 and H. pylori-cagA(+) in the intestinal adenocarcinoma type. MSI was correlated with hMLH1 methylation. There was an inverse correlation between DAPK hypermethylation and MSI.
We found a strong association between CDH1 methylation and H. pylori-cagA(+) in intestinal-type gastric cancer, association of MSI and better prognosis and an heterogeneous COX-2 overexpression.
检测 CDH1、DAPK、COX2、hMLH1 和 CDKN2A 基因的甲基化状态，并分析其与胃腺癌中幽门螺杆菌（H. pylori）-cagA(+)和 Epstein Barr 病毒（EBV）感染的关系。
采用甲基化特异性 PCR（MSP）法检测 89 例原发性胃腺癌（肠型和弥漫型）中上述基因的甲基化状态。采用 BAT26 引物对微卫星不稳定性（MSI）进行分析，PCR 产物用 ABI PRISM 3100 遗传分析仪，基因扫描 3.7 软件（Applied Biosystems）进行分析。采用特异性引物检测 H. pylori 和 cagA 基因，通过 PCR 检测 H. pylori，并用聚合酶链反应-原位杂交法检测 EBV。采用卡方检验或 Fisher 确切概率法进行统计学分析。
最常见的高甲基化基因是 COX-2（63.5%），其次是 DAPK（55.7%）、CDH1（51%）、CDKN2A（36%）和 hMLH1（30.3%）。肠型和弥漫型腺癌具有不同的甲基化谱，并且在肠型腺癌中，E-CDH1 的甲基化与 H. pylori-cagA(+)之间存在关联。MSI 与 hMLH1 甲基化相关。DAPK 高甲基化与 MSI 呈负相关。
我们发现 CDH1 甲基化与胃腺癌肠型中 H. pylori-cagA(+)之间存在强烈关联，MSI 与较好的预后相关，COX-2 过表达具有异质性。
