Effect of Helicobacter pylori infection on Bax protein expression in patients with gastric precancerous lesions

Abstract

Aim: To investigate the effect of Helicobacter pylori (H pylori) infection on Bax protein expression, and explore the role of H pylori in gastric carcinogenesis. Methods: H pylori was assessed by rapid urease test and Warthin-Starry method, and expression of Bax protein was examined immunohistochemically in 72 patients with pre-malignant lesions. Results: Bax protein was differently expressed in intestinal metaplasia and gastric dysplasia, and showed 63.99% positivity. The positivity of Bax protein expression in H pylori-positive gastric precancerous lesions (72.3%) was significantly higher than that in H pylori-negative gastric precancerous lesions (48.0%, χ2 = 4.191, P<0.05). H pylori infection was well correlated with the expression of Bax protein in gastric precancerous lesions (r= 0.978, P<0.01). After eradication of H pylori, the positivity of Bax protein expression significantly decreased in H pylori-positive gastric precancerous lesions (χ2 = 5.506, P<0.05). In the persisting H pylori-infected patients, the positivity of Bax protein expression was not changed. Conclusion: H pylori infection may be involved in the upregulation of Bax gene, which might be one of the mechanisms of H pylori infection-induced gastric epithelial cell apoptosis. H pylori might act as a tumor promoter in the genesis of gastric carcinoma and eradication of H pylori could inhibit gastric carcinogenesis. © 2005 The WJG Press and Elsevier Inc. All rights reserved.