title: Inactivation of helicase-like transcription factor by promoter hypermethylation in human gastric cancer.
abstract: Helicase-like transcription factor (HLTF), a member of the SWI/SNF (mating type switching/sucrose nonfermenting) chromatin-remodeling complex, is recently found to be inactivated by promoter hypermethylation in human colorectal cancer. However, the role of this putative tumor suppressor gene in other tumors has not been determined. We evaluated the role of HLTF promoter hypermethylation in gastric cancer. Expression of HLTF was examined by reverse-transcription (RT)-polymerase chain reaction (PCR), and promoter hypermethylation in HLTF was determined by methylation-specific PCR. Bisulfite DNA sequencing was performed to determine the detailed methylation profiles of the promoter region. HLTF expression was lost in two of five gastric cell lines and in 13 (28%) of 46 primary gastric cancers. Accordingly, promoter hypermethylation was detected in the two cell lines and in nine of 13 gastric cancer samples. Of the ten normal gastric specimens and ten paired adjacent nonneoplastic tissues, methylation was detected in only one adjacent nonneoplastic tissue. Bisulfite DNA sequencing of the promoter region of HLTF showed that the CpG island was densely methylated in cell lines and cancer samples; this also appeared to correlate with expression level. Treatment of gastric cell lines that lacked HLTF expression with the demethylating agent 5-azacytidine (5-azaDC) restored HLTF expression. These results suggest that HLTF promoter hypermethylation is frequently demonstrated in human gastric cancer, and inactivation of HLTF or the chromatin-remodeling complex may play a crucial role in gastric carcinogenesis.
authors.affiliation: Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong.
authors.forename: Wai K
authors.initials: WK
authors.lastname: Leung
authors.forename: Jun
authors.initials: J
authors.lastname: Yu
authors.forename: Alfa H C
authors.initials: AH
authors.lastname: Bai
authors.forename: Michael W Y
authors.initials: MW
authors.lastname: Chan
authors.forename: Ka-Kui
authors.initials: KK
authors.lastname: Chan
authors.forename: Ka-Fai
authors.initials: KF
authors.lastname: To
authors.forename: Francis K L
authors.initials: FK
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: D048868:Adaptor Proteins, Signal Transducing; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D001374:Azacitidine / Q000494:pharmacology; D002352:Carrier Proteins; D018899:CpG Islands; D019175:DNA Methylation / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D005753:Gastric Mucosa / Q000166:cytology / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D006801:Humans; D000070957:MutL Protein Homolog 1; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000502:physiology*; D017422:Sequence Analysis, DNA / Q000379:methods; D013274:Stomach Neoplasms / Q000235:genetics* / Q000378:metabolism; D013447:Sulfites / Q000737:chemistry; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000964:Antimetabolites, Antineoplastic; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C100023:HLTF protein, human; C501486:MLH1 protein, human; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D013447:Sulfites; D014157:Transcription Factors; D000070957:MutL Protein Homolog 1; D001374:Azacitidine