Promoter methylation of E-cadherin gene in gastric mucosa associated with Helicobacter pylori infection and in gastric cancer

Background: E-cadherin is an adhesion molecule involved in tumour invasion/metastasis. Silencing of E-cadherin by promoter CpG methylation has been shown in both familial and sporadic gastric cancers. Helicobacter pylori is a class I carcinogen in gastric cancer. Aims: This study was undertaken to investigate the association between methylation of E-cadherin and H pylori in gastric mucosa from dyspeptic patients, and in intestinal metaplasia and primary and meta-static adenocarcinoma from surgical specimens of patients with gastric cancer. Methods: E-cadherin methylation was studied using methylation specific polymerase chain reaction in microdissected tissue from biopsies or surgical resection specimens. E-cadherin expression was studied by immunohistochemistry. Results: E-cadherin methylation was present in 31% (11/35) of gastric mucosae from dyspeptic patients, and was associated with H pylori infection (p=0.002), but was independent of the age of the patient or presence or absence of gastritis. E-cadherin methylation was present in 0% (0/8) of normal mucosa, 57% (12/21) of intestinal metaplasias, and 58% (15/26) of primary and 65% (21/32) of metastatic cancers. E-cadherin methylation status was concordant in 92% (11/12) of intestinal metaplasias and primary cancers, and in 85% (17/20) of primary and metastatic cancers from the same resected specimen. E-cadherin methylation in gastric cancer was associated with depth of tumour invasion (p=0.02) and regional nodal metastasis (p=0.05). Conclusion: E-cadherin methylation is an early event in gastric carcinogenesis, and is initiated by H pylori infection.