Association of COX-2 genetic polymorphisms and H pylori infection with gastric cancer in high-incidence Hexi area of Gansu Province in China

Abstract

AIM: To investigate the relationship among cyclooxygenase-2 (COX-2) polymorphisms (COX-2-899G＞C and COX-2 codon587G＞A), H pylori infection and susceptibility to gastric cancer in high-incidence Hexi area of Gansu, Province in China. METHODS: Blood samples were collected from 140 patients with gastric carcinoma and 125 nor mal persons in Hexi area of Gansu Province. Ge nomic DNA was extracted by phenol chloroform method and polymorphisms of COX-2-899G＞C (G to C) and codon 587G＞A (G to A) were genotyped by PCR-TaqMan. For detection of H pylori infection, Warhin-starry staining was used. RESULTS: Three kinds of COX-2-899G＞C genotypes were found, including GG, GC and CC. Their frequencies in gastric cancer patients were 72.9%, 21.4%, 5.7% and their frequencies in the normal controls were 84.0%, 12.8%, 3.2%, respectively. COX-2-899C carriers had an increased risk of gastric carcinoma (OR=1.956, 95%CI: 1.067-3.586).COX-2 587codonG＞A included three genotypes: G/G, G/A and A/A. Their frequencies in the cancer patients were 86.4%, 11.4%, 2.2%, and in the normal controls were 89.6%, 9.6%, 0.8%, respectively. However, No significant differences of COX-2 587codon G＞A polymorphisms were observed between the cancer patients and the normal controls in each genotype. The rate of H pylori infection was significantly higher in the cancer patients than that in the healthy control (68.6% vs 50.4%, P=0.003). Stratification analysis showed that COX-2 -899C carrier with H pylori infection had a higher risk for gastric cancer (OR=2.471, 95%CI: 1.076-5.675). CONCLUSION: COX-2 -899C genotype may increase the susceptibility to gastric cancer in high-incidence Hexi area of Gansu province in China. In addition, H pylori infection and COX-2-899C playa synergic role in gastric cancer pathogenesis. However, COX-2 codon 587G＞A has no relation with gastric cancer in this area.