title: Promoter hypermethylation of tumor-related genes in gastric intestinal metaplasia of patients with and without gastric cancer.
abstract: Promoter hypermethylation is an alternative mechanism of gene silencing in human cancers including gastric cancer. While intestinal metaplasia (IM) is generally regarded as a precancerous lesion of the stomach, our study examines the presence of gene promoter hypermethylation in IM of patients with and without gastric cancer. We examined 31 samples of gastric cancer, 36 gastric IM (21 associated with gastric cancer and 15 from noncancer patients) and 10 normal gastric biopsies. Tissues containing foci of IM were carefully microdissected from paraffin-embedded section. Bisulfite-modified DNA was examined for gene promoter hypermethylation in DAP-kinase, E-cadherin, GSTP1, p14, p15, p16, RASSF1A and hMLH1 by methylation-specific-PCR. None of the control gastric tissues had hypermethylation detected, but gene promoter hypermethylation was frequently detected in gastric cancer and IM. The mean number of methylated genes in cancer and IM was 3.0 and 1.4, respectively (p < 0.0001). Methylation in IM from cancer patients was all associated with concurrent methylation in the corresponding tumor samples. The numbers of methylated genes were similar in IM obtained from cancer and noncancer patients. By examining the methylation patterns of these genes, 3 differential methylation patterns were recognized: hypermethylation was more frequent in cancer than in IM (DAP-kinase, p14, p15 and p16); comparable frequencies of methylation in cancer and IM (E-cadherin and hMLH1); and no methylation (GSTP1). Aberrant methylation in tumor-related genes is frequently detected in gastric IM of both cancer and noncancer patients, suggesting their early involvement in the multistep progression of gastric carcinogenesis.
authors.affiliation: Department of Anatomical and Cellular Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong.
authors.forename: Ka-Fai
authors.initials: KF
authors.lastname: To
authors.forename: Wai K
authors.initials: WK
authors.lastname: Leung
authors.forename: Tin-Lap
authors.initials: TL
authors.lastname: Lee
authors.forename: Jun
authors.initials: J
authors.lastname: Yu
authors.forename: Joanna H M
authors.initials: JH
authors.lastname: Tong
authors.forename: Michael W Y
authors.initials: MW
authors.lastname: Chan
authors.forename: Enders K W
authors.initials: EK
authors.lastname: Ng
authors.forename: S C Sydney
authors.initials: SC
authors.lastname: Chung
authors.forename: Joseph J Y
authors.initials: JJ
authors.lastname: Sung
mesh_terms: D000368:Aged; D051017:Apoptosis Regulatory Proteins; D015820:Cadherins / Q000235:genetics; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics; D019175:DNA Methylation; D064550:Death-Associated Protein Kinases; D005260:Female; D005753:Gastric Mucosa / Q000473:pathology*; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase / Q000235:genetics; D006801:Humans; D007527:Isoenzymes / Q000235:genetics; D008297:Male; D008679:Metaplasia; D008875:Middle Aged; D011401:Promoter Regions, Genetic; D013274:Stomach Neoplasms / Q000235:genetics* / Q000473:pathology
chemical_list: D051017:Apoptosis Regulatory Proteins; D015820:Cadherins; D007527:Isoenzymes; C496556:GSTP1 protein, human; D051549:Glutathione S-Transferase pi; D005982:Glutathione Transferase; D064550:Death-Associated Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases