title: Identification of methylation profile of HOX genes in extrahepatic cholangiocarcinoma.
abstract: OBJECTIVE
  To identify methylation profile and novel tumor marker of extrahepatic cholangiocarcinoma (CCA) with high throughout microarray.
  
  
  METHODS
  Differential methylation profile was compared between normal bile duct epithelial cell lines and CCA cell lines by methyl-DNA immunoprecipitation (MeDIP) microarray. Bisulfite-polymerase chain reaction (BSP) was performed to identify the methylated allels of target genes. Expression of target genes was investigated before and after the treatment with DNA demethylating agent. Expression of candidate genes was also evaluated by immunofluorescence in 30 specimens of CCA tissues and 9 normal bile duct tissues.
  
  
  RESULTS
  Methylation profile of CCA was identified with MeDIP microarray in the respects of different gene functions and signaling pathways. Interestingly, 97 genes with hypermethylated CpG islands in the promoter region were homeobox genes. The top 5 hypermethylated homeobox genes validated by BSP were HOXA2 (94.29%), HOXA5 (95.38%), HOXA11 (91.67%), HOXB4 (90.56%) and HOXD13 (94.38%). Expression of these genes was reactivated with 5'-aza-2'-deoxycytidine. Significant expression differences were found between normal bile duct and extrahepatic CCA tissues (66.67%-100% vs 3.33%-10%).
  
  
  CONCLUSIONS
  HOXA2, HOXA5, HOXA11, HOXB4 and HOXD13 may work as differential epigenetic biomarkers between malignant and benign biliary tissues.
authors.affiliation: General Surgery Department of Tongji Hospital, Tongji Medical College of Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, Hubei Province, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Shu
authors.forename: Bing
authors.initials: B
authors.lastname: Wang
authors.forename: Ji
authors.initials: J
authors.lastname: Wang
authors.forename: Jian-Ming
authors.initials: JM
authors.lastname: Wang
authors.forename: Sheng-Quan
authors.initials: SQ
authors.lastname: Zou
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000378:metabolism; D001374:Azacitidine / Q000031:analogs & derivatives / Q000378:metabolism; D001650:Bile Duct Neoplasms / Q000235:genetics* / Q000473:pathology; D014408:Biomarkers, Tumor / Q000235:genetics; D018281:Cholangiocarcinoma / Q000235:genetics* / Q000473:pathology; D019175:DNA Methylation; D000077209:Decitabine; D015972:Gene Expression Regulation, Neoplastic; D053263:Gene Regulatory Networks; D005801:Genes, Homeobox; D006801:Humans; D046228:Microarray Analysis
chemical_list: D000964:Antimetabolites, Antineoplastic; D014408:Biomarkers, Tumor; D000077209:Decitabine; D001374:Azacitidine