Effect of Helicobacter pylori infection on the expression of DNA Mismatch Repair Protein

Aim : To determine the expression of DNA MMR proteins, including hMLH1 and hMSH2, in gastric epithelial cells of patients with or without H. pylori infected gastritis. Background : Impairment of DNA mismatch repair (MMR) system is a known mechanism of carcinogenesis and tumor progression in both sporadic and hereditary human cancers. Patients and methods : Fifty H.pylori-positive patients and 50 H.pylori-negative subjects were enrolled in the study. During endoscopy of patients with non-ulcer dyspepsia, 2 antral and 2 corpus biopsies were taken for histologic examination (Giemsa stain) and immunohistochemical staining on hMLH1 and hMSH2. Results : The percentage of epithelial cell nuclei demonstrating positivity for hMLH1 staining was 84.14±7.32 in H.pylori-negative subjects in comparison of 73.34±10.10 in H.pylori-positive patients (p Conclusion : Study indicates that H.pylori might promote development of gastric carcinoma at least in part through the ability to affect the DNA MMR system.