title: Epigenetic inactivation of the SFRP1 gene in esophageal squamous cell carcinoma.
abstract: BACKGROUND
  The secreted frizzled-related protein 1 (SFRP1) gene, as a Wnt signaling modulator, is frequently inactivated by promoter methylation in many tumors including gastric cancer, breast cancer, oral squamous cell carcinoma, and esophageal adenocarcinoma. However, the role of SFRP1 in esophageal squamous cell carcinoma (ESCC) is not clear. In this study, we investigated the epigenetic inactivation of the SFRP1 gene in ESCC.
  
  
  METHODS
  Nine ESCC cell lines, two immortalized human esophageal epithelial cell lines, twenty ESCC tissues, and paired adjacent nontumor tissues were analyzed in the study. Methylation-specific polymerase chain reaction (PCR), bisulfite sequencing, reverse-transcription PCR, immunohistochemistry, and chromatin immunoprecipitation assay were used to detect SFRP1 promoter methylation, expression of the SFRP1 gene, and histone modification in the SFRP1 promoter region.
  
  
  RESULTS
  The SFRP1 promoter was found to be highly methylated in 95% (19/20) of the ESCC tissues and in nine ESCC cell lines, compared with 65% (13/20) of the paired nontumor tissues. Moreover, we confirmed that complete methylation of the SFRP1 gene promoter was correlated with its greatly reduced expression level. After individual treatment with 5-aza-2'-deoxycytidine (DAC) and trichostatin A (TSA), the messenger RNA (mRNA) level of the SFRP1 gene was not obviously rescued in the EC9706 cell line. Combined incubation with DAC and TSA can, however, substantially increase the SFRP1 mRNA expression level in the EC9706 cell line. Chromatin immunoprecipitation assay showed that acetylated histone H3 and H4 were found in the SFRP1 promoter region.
  
  
  CONCLUSIONS
  Promoter hypermethylation of SFRP1 is a frequent event in ESCC. Promoter methylation and histone acetylation may cooperatively regulate expression of the SFRP1 gene.
authors.affiliation: Department of Gastroenterology, Beijing Friendship Hospital Affiliated to the Capital Medical University, 95 Yong'an Road, 100050 Beijing, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Meng
authors.forename: Qing-Gang
authors.initials: QG
authors.lastname: Wang
authors.forename: Jun-Xiong
authors.initials: JX
authors.lastname: Wang
authors.forename: Sheng-tao
authors.initials: ST
authors.lastname: Zhu
authors.forename: Yue
authors.initials: Y
authors.lastname: Jiao
authors.forename: Peng
authors.initials: P
authors.lastname: Li
authors.forename: Shu-tian
authors.initials: ST
authors.lastname: Zhang
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor / Q000187:drug effects; D019175:DNA Methylation; D000077209:Decitabine; D004938:Esophageal Neoplasms / Q000235:genetics* / Q000378:metabolism; D020868:Gene Silencing; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D000094742:Secreted Frizzled-Related Proteins
chemical_list: D000964:Antimetabolites, Antineoplastic; D001374:Azacitidine; D000077209:Decitabine; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C117636:SFRP1 protein, human; D000094742:Secreted Frizzled-Related Proteins; C012589:trichostatin A