RESUMEN
PURPOSE: Promoter hypermethylation of E-cadherin plays an important role on gastric cancer development. Whereas E-cadherin methylation was frequently detected in the stomach of Helicobacter pylori-infected individuals, we tested whether eradication of H. pylori alters the methylation status of the noncancerous gastric epithelium. EXPERIMENTAL DESIGN: Endoscopic biopsies were taken from the antrum and corpus of H. pylori-infected subjects without gastric cancer. Presence of methylated E-cadherin sequences in the gastric specimens was detected by methylation-specific PCR. Bisulfite DNA sequencing was done to determine the topographical distribution and changes in methylation profiles with H. pylori eradication. RESULTS: Among the 28 H. pylori-infected subjects (median age, 44.5 years), 15 (53.6%) had E-cadherin methylation detected in stomach at baseline. Discordant methylation patterns between the antrum and corpus were noted in six patients. One year after successful H. pylori eradication, there was a significant reduction in the methylation density of the promoter region and exon 1 of the E-cadherin gene as detected by bisulfite DNA sequencing (P < 0.001). CONCLUSION: Promoter methylation in E-cadherin was frequently detected in the stomach of H. pylori-infected individuals. Eradication of H. pylori might possibly reduce the methylation density in E-cadherin gene and the chance of subsequent neoplastic transformation.