Aim: To determine the expression of DNA (MMR) proteins, including hMLH1 and hMSH2, in gastric epithelial cells in the patients with or without Helicobacter pylori (H pylori)-infected gastritis.
Methods: Fifty H pylori-positive patients and 50 H pylori-negative patients were enrolled in the study. During endoscopy of patients with non-ulcer dyspepsia, two antral and two corpus biopsies were taken for histological examination (Giemsa stain) and for immunohistochemical staining of hMLH1 and hMSH2.
Results: The percentage of epithelial cell nuclei that demonstrated positivity for hMLH1 staining was 84.14 +/- 7.32% in H pylori-negative patients, while it was 73.34 +/- 10.10% in H pylori-positive patients (P < 0.0001). No significant difference was seen between the two groups regarding the percentage of epithelial cell nuclei that demonstrated positivity for hMSH2 staining (81.16 +/- 8.32% in H pylori-negative versus 78.24 +/- 8.71% in H pylori-positive patients; P = 0.09).
Conclusion: This study indicates that H pylori might promote development of gastric carcinoma at least in part through its ability to affect the DNA MMR system.