The GPX1 Pro198Leu polymorphism in gastric cancer patients with and without Helicobacter pylori infection

Helicobacter pylori infection could induce oxidative stress. Oxidative stress is involved in the pathogenesis of gastric diseases. Glutathione peroxidase 1 (GPX1), is part of the enzymatic antioxidant defense, preventing oxidative damage. The aim of the present study was to assess the association of GPX1 Pro(198)Leu genotypes with gastric cancer in patients with and without H. pylori infection in a population of Northern Iran. The present case-control study consisted of 50 patients with gastric cancer and 78 cancer-free subjects as controls. Extraction of DNA was performed on bioptic samples and the GPX1 genotypes were identified using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The frequencies of GPX1 Pro/Pro, Pro/Leu and Leu/Leu genotypes in controls were 21.8, 71.8 and 6.4%, respectively. However, in gastric cancer patients, the frequencies of 34, 56 and 10% were observed for Pro/Pro, Pro/Leu and Leu/Leu genotypes, respectively (p = 0.185). In 38 (76%) patients infected with H. pylori, the frequencies of Pro and Leu alleles were 94.7 and 3.3%, respectively. There was a higher frequency of combined genotype of Pro/Leu + Leu/Leu (94.7%) in H. pylori positive patients than that in patients without H. pylori infection (75%, p = 0.047). The presence of this genotype tended to increase the risk of H. pylori related gastric cancer by 5.88-fold (p = 0.069) in our population. Our findings indicated the absence of association between the GPX1 Pro(198)Leu polymorphism and the risk of gastric cancer in an Iranian population. However, we detected an association between H. pylori related gastric cancer with GPX1 Pro/Leu + Leu/Leu genotype.