Comparative analysis of glutathione transferase genetic polymorphism, Helicobacter pylori and Epstein-Barr virus between the tumor area and the proximal and distal resection margins of gastric cancer.

ABSTRACT Objective: to compare the polymorphism of the Glutathione S-transferase theta 1 (GSTT1) and Glutathione S-transferase mu 1 (GSTM1) genes from the tumor area with the proximal and distal margins of stomach specimens resected from patients with gastric cancer, and to investigate the presence of Epstein-Barr virus (EBV) DNA and Helicobacter pylori. Methods: we prospectively collected tissue specimens from the tumor area and from the proximal and distal resection margins of the stomachs of ten patients with gastric adenocarcinoma who underwent gastrectomy with D2 lymphadenectomy, and submitted these specimens to DNA extraction. We compared the tumor area with the proximal and distal margins of the resected stomachs for polymorphism of GSTT1 and GSTM1 genes and investigated the presence of EBV-DNA and H. pylori. We used the p53 exon 5 gene as an internal control of the multiplex PCR reaction. Results: in one patient, we detected null GSTT1 and GSTM1 genotypes in the tumor area, in contrast to the presence of both genes in the proximal and distal margins. We found EBV-DNA and H. pylori in the tumor area and also in the proximal and distal margins. In another patient, the proximal margin was negative for GSTT1, and EBV-DNA was negative in the distal margin. In three patients, EBV-DNA was negative only in the distal margin. Conclusion: this is the first report where different genotypes, EBV-DNA and H. pylori infection were observed in the same patient, indicating a probable deletion of these genes in response to tumor progression and intratumoral heterogeneity.

摘要 目的：比较胃癌根治术后患者胃标本肿瘤区域与近端、远端切缘的谷胱甘肽S-转移酶θ1（GSTT1）、谷胱甘肽S-转移酶μ1（GSTM1）基因多态性，并检测爱泼斯坦-巴尔病毒（EBV）DNA与幽门螺杆菌（Helicobacter pylori）的存在情况。方法：前瞻性纳入10例行D2淋巴结清扫术胃切除术的胃腺癌患者，收集其肿瘤区域及胃近端、远端切缘的组织标本并进行DNA提取。比较上述肿瘤区域与近端、远端切缘的GSTT1、GSTM1基因多态性，同时检测EBV DNA与幽门螺杆菌的存在情况；以p53第5外显子基因作为多重聚合酶链反应（multiplex PCR）的内参对照。结果：1例患者的肿瘤区域检出GSTT1与GSTM1基因缺失型，而其近端、远端切缘均存在这两种基因；在肿瘤区域、近端及远端切缘中均检出EBV DNA与幽门螺杆菌。另有1例患者的近端切缘GSTT1呈阴性，远端切缘EBV DNA呈阴性；3例患者仅远端切缘EBV DNA呈阴性。结论：本研究为首次报道同一患者的不同基因型、EBV DNA及幽门螺杆菌感染情况存在差异，提示上述基因的缺失可能与肿瘤进展及肿瘤内异质性相关。