Alterations of Cyclooxygenase-2 Methylation Levels Before and After Intervention Trial to Prevent Gastric Cancer in a Chinese Population.

To explore the epigenetic mechanisms underlying the effects of anti-Helicobacter pylori (H. pylori) alone and combined with COX-2 inhibitor (celecoxib), we dynamically evaluated the associations between COX-2 methylation alterations and gastric lesion evolution during the process of interventions. In a total of 809 trial participants COX-2 methylation levels were quantitatively detected before and after treatment. The self-comparison at the same stomach site for each subject showed significant methylation alteration differences among intervention groups (P < 0.001). With placebo group as reference, COX-2 methylation levels were decreased in anti-H. pylori [OR, 3.30; 95% confidence interval (CI), 2.16-5.02], celecoxib (OR, 2.04; 95% CI, 1.36-3.07), and anti-H. pylori followed by celecoxib (OR, 2.10; 95% CI, 1.38-3.17) groups. When stratified by baseline histology, the three active arms significantly decreased COX-2 methylation levels in indefinite dysplasia/dysplasia subjects, and ORs were 3.65 (95% CI, 1.96-6.80) for anti-H. pylori, 2.43 (95% CI 1.34-4.39) for celecoxib, and 2.80 (95% CI, 1.52-5.15) for anti-H. pylori followed by celecoxib, respectively. No additive effect on COX-2 methylation was found for anti-H. pylori followed by celecoxib than two treatments alone. Compared with subjects without methylation reduction, higher opportunity for gastric lesion regression was found in subjects with decreased COX-2 methylation levels, especially for indefinite dysplasia/dysplasia subjects (OR, 1.92; 95% CI, 1.03-3.60). These findings suggest that anti-H. pylori or celecoxib treatment alone could decrease COX-2 methylation levels in gastric mucosa. COX-2 methylation alteration was associated with the regression of indefinite dysplasia/dysplasia, which might serve as a potential biomarker for chemoprevention efficacy. Cancer Prev Res; 9(6); 484-90. ©2016 AACR.