title: Helicobacter pylori-infection-associated CpG island hypermethylation in the stomach and its possible association with polycomb repressive marks.
abstract: Helicobacter pylori infection can induce CpG island (CGI) hypermethylation in gastric mucosa. Recently, genes occupied by Polycomb proteins in embryonic stem cells were shown to be vulnerable to aberrant DNA hypermethylation in cancers. To explore the relationship between H. pylori infection and DNA methylation changes in neoplastic and non-neoplastic stomach, we analyzed 25 CGIs and repetitive DNA elements from 82 chronic gastritis and 69 gastric carcinomas. Twenty-three CGIs showed significantly higher methylation levels in H. pylori-negative gastric carcinoma (n = 28) than in H. pylori-negative chronic gastritis (n = 39; P < 0.05), indicating cancer-associated methylation. Eight CGIs exhibited significantly higher methylation levels in H. pylori-positive chronic gastritis (n = 43) than in H. pylori-negative chronic gastritis (n = 39; P < 0.05). Six CGIs showed both cancer-associated and H. pylori-associated hypermethylation. Six (75%) of the eight H. pylori-associated hypermethylated genes contained at least one of three repressive marks (Suzl2 occupancy, Eed occupancy, histone H3 K27 trimethylation), whereas 31% of the remaining cancer-associated hypermethylated genes had at least one mark. The findings suggest that H. pylori infection strongly induces CGI hypermethylation in gastric epithelial cells and that susceptibility to H. pylori-induced DNA hypermethylation may be determined by Polycomb repressive marks in stem or progenitor cells.
authors.affiliation: Laboratory of Epigenetics, Cancer Research Institute, Seoul National University College of Medicine, Seoul, South Korea.
authors.forename: Eun Joo
authors.initials: EJ
authors.lastname: Yoo
authors.forename: Seog-Yun
authors.initials: SY
authors.lastname: Park
authors.forename: Nam-Yun
authors.initials: NY
authors.lastname: Cho
authors.forename: Nayoung
authors.initials: N
authors.lastname: Kim
authors.forename: Hye Seung
authors.initials: HS
authors.lastname: Lee
authors.forename: Gyeong Hoon
authors.initials: GH
authors.lastname: Kang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D020087:Alu Elements / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics; D018899:CpG Islands / Q000235:genetics*; D004247:DNA / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D005756:Gastritis / Q000235:genetics* / Q000382:microbiology; D016481:Helicobacter Infections / Q000235:genetics*; D016480:Helicobacter pylori; D006657:Histones / Q000235:genetics; D006801:Humans; D020084:Long Interspersed Nucleotide Elements / Q000235:genetics; D008875:Middle Aged; D009363:Neoplasm Proteins; D009687:Nuclear Proteins / Q000235:genetics; D063151:Polycomb Repressive Complex 2; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins / Q000235:genetics*; D013274:Stomach Neoplasms / Q000235:genetics* / Q000382:microbiology; D014157:Transcription Factors
chemical_list: D002352:Carrier Proteins; D004273:DNA, Neoplasm; C491488:EED protein, human; D006657:Histones; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins; C430461:SUZ12 protein, human; D014157:Transcription Factors; D004247:DNA; D063151:Polycomb Repressive Complex 2