Association of LEC and tnpA Helicobacter pylori genes with gastric cancer in a Brazilian population

Abstract Background H. pylori seroprevalence in Brazilians varies and is dependent on socioeconomic status, sanitation conditions and ethnicity; furthermore, H. pylori is not always associated with the incidence of gastric cancer, suggesting the role of more virulent strains. The purpose of this study was to analyze the association of more virulent H. pylori strains with gastric cancer. Methods DNA was extracted from gastric biopsies of thirty-four cases of gastric cancer (11 intestinal-type, 23 diffuse-type), and thirty-four of patients with endoscopic gastritis. The presence of cagPAI genes (cagA, cagA promoter, cagE, cagM, tnpB, tnpA, cagT and the left end of the cagII (LEC)) and babA were analyzed by PCR. Results Comparison of H. pylori isolates from gastric cancer and gastritis patients showed significant associations of tnpA and LEC with gastric cancer (73.5% [OR, 6.66; 95% CI, 2.30-19.25] and 58.8% [OR, 10.71; 95% CI, 3.07-37.28] of cases, respectively). Other cagPAI genes were detected in both groups at similar frequencies. Conclusions tnpA and LEC of H. pylori cagPAI were associated with gastric cancer; nonetheless, these results were restricted within this group of patients and further studies are needed to confirm these results in a larger sample and determine their role in gastric carcinogenesis.

The authors thank Luis Claudio Alfaia Mendes for performing endoscopies of several patients and Démerson André Polli for helping with the statistical analysis. The molecular genetic studies were partially supported by CAPES (Coordenação de aperfeiçoamento de pessoal de nível superior) and Fundação Faculdade de Medicina. Publication charges and English revision were supported by Fundação Faculdade de Medicina and CAPES/University of São Paulo School of Medicine.

The authors thank Luis Claudio Alfaia Mendes for performing endoscopies of several patients and Démerson André Polli for helping with the statistical analysis. The molecular genetic studies were partially supported by CAPES (Coordenação de aperfeiçoamento de pessoal de nível superior) and Fundação Faculdade de Medicina. Publication charges and English revision were supported by Fundação Faculdade de Medicina and CAPES/University of São Paulo School of Medicine.