title: Promoter methylation regulates cigarette smoke-stimulated cyclooxygenase-2 expression in esophageal squamous cell carcinoma.
abstract: OBJECTIVE
  Cigarette smoke extracts (CSE) could promote esophageal squamous cell carcinoma (ESCC) through upregulation of cyclooxygenase-2 (COX-2) expression. Promoter methylation mediates the transcriptional modulation of the COX-2 gene. The aim of the study was to explore whether COX-2 promoter methylation regulated COX-2 expression and functional activity in ESCC exposed to CSE.
  
  
  METHODS
  The methylation status of COX-2 promoter in two human ESCC cell lines, EC109 and TE-1, was examined using bisulfite sequencing analysis. COX-2 mRNA and protein expression were detected by reverse-transcription polymerase chain reaction and Western blot. Prostaglandin E₂ (PGE₂) was examined by enzyme linked immunosorbent assay (ELISA).
  
  
  RESULTS
  The promoter was hypermethylated in TE-1 which had a low level of COX-2 expression and was hypomethylated in EC109 with a relatively high level of COX-2 expression. Stimulation by cigarette smoke ethanol extract (EE) resulted in increased COX-2 expression in EC109, but not in TE-1. Treatment with 5-aza-2'-deoxycytidine (5-aza-DC) demethylated the promoter and upregulated COX-2 expression as well as PGE(2) production in TE-1, especially followed by EE stimulation. No significant effect was observed in EC109.
  
  
  CONCLUSIONS
  These findings suggest that promoter methylation may be one of the mechanisms regulating COX-2 expression in ESCC in response to stimulation of CSE.
authors.affiliation: Department of Gastroenterology, Beijing Friendship Hospital, Capital Medical University, China.
authors.forename: Xin Ying
authors.initials: XY
authors.lastname: Meng
authors.forename: Sheng Tao
authors.initials: ST
authors.lastname: Zhu
authors.forename: Qiao Zhi
authors.initials: QZ
authors.lastname: Zhou
authors.forename: Peng
authors.initials: P
authors.lastname: Li
authors.forename: Yong Jun
authors.initials: YJ
authors.lastname: Wang
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 / Q000188:drug therapy / Q000235:genetics* / Q000503:physiopathology; D045744:Cell Line, Tumor; D051546:Cyclooxygenase 2 / Q000235:genetics* / Q000378:metabolism; D019175:DNA Methylation / Q000502:physiology*; D000077209:Decitabine; D004938:Esophageal Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000503:physiopathology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000502:physiology; D006801:Humans; D011401:Promoter Regions, Genetic / Q000502:physiology; D012907:Smoking / Q000009:adverse effects / Q000235:genetics*
chemical_list: D000964:Antimetabolites, Antineoplastic; D000077209:Decitabine; D051546:Cyclooxygenase 2; D001374:Azacitidine