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目的 探讨中国人诱导型一氧化氮合酶 (iNOS)基因多态性与胃癌易感性的关系。方法 以社区为基础的病例对照研究。病例经胃镜及病理确诊 ,有效分析样本包括肠型胃癌 93例 ,胃贲门癌 5 0例 ,对照 2 4 6人。结果 iNOS基因第 16外显子存在C→T多态性 (产生Tsp 5 0 9Ⅰ内切酶的识别位点 ) ,使编码的氨基酸由丝氨酸 (Ser)改变为亮氨酸 (Leu) ,对照人群T等位基因频率为13.2 1% ,单独存在C→T多态性与肠型胃癌、胃贲门癌易感性增加无统计学关联 ,但与吸烟因素同时存在 ,对肠型胃癌、胃贲门癌产生明显的 2型超相乘交互作用 ;与缺乏CagA抗体同时存在 ,对胃贲门癌产生明显的相加交互作用。结论 iNOS基因C→T多态性可能是胃癌的易感基因 ,特别与吸烟、缺乏幽门螺杆菌CagA抗体的肠型胃癌、胃贲门癌发生密切相关。
Objective To investigate the relationship between Chinese inducible nitric oxide synthase (iNOS) gene polymorphism and gastric cancer susceptibility. Methods Community-based case-control study. The cases were diagnosed by endoscopy and pathology. The effective samples included 93 cases of enteric gastric cancer, 50 cases of gastric cardia carcinoma and 246 controls. Results There was a C → T polymorphism in the exon 16 of iNOS gene (the recognition site of Tsp509I endonuclease was generated), and the encoded amino acid was changed from Ser to Leu. T allele frequency was 13.2%. There was no statistical relationship between the C → T polymorphism and the susceptibility of intestinal gastric cancer and gastric cardia cancer. However, there was no significant correlation between smoking and C-T polymorphism. Obvious type 2 hyper-multiplication interactions; coexisting with lack of CagA antibodies have a significant additive interaction on gastric cardia. Conclusion The C → T polymorphism of iNOS gene may be a susceptibility gene of gastric cancer, especially closely related to smoking, lack of CagA antibody of H. pylori and gastric cardia cancer.