title: Mechanism and clinical significance of cyclooxygenase-2 expression in gastric cancer.
abstract: OBJECTIVE
  To determine the correlation between methylation status of 5' CpG island of cyclooxygenase-2 (COX-2) gene and protein expression in gastric cancer tissues for distinguishing the molecular characters of gastric cancers.
  
  
  METHODS
  Methylation status of 5' CpG island of COX-2 gene was studied by PCR amplification after HpaII and Hha I restrictive enzyme digestion; COX-2 expression was evaluated by immunohistochemical method.
  
  
  RESULTS
  Hpa II and HhaI site were all methylated in 12 normal gastric mucosa tissues, whereas they were demethylated in 77.27% (34/44) and 84.09% (37/44) gastric cancer tissues, respectively. Expression of COX-2 was detected in 68.18% (30/44) gastric cancer tissues, but no expression was found in normal gastric mucosa tissues. In gastric cancer tissues, COX-2 expression was correlated significantly with HpaII site demethylation (29/30 vs 5/14, P<0.001 and HhaI site demethylation (28/30 vs 9/14, P<0.05).
  
  
  CONCLUSIONS
  The demethylation of 5' CpG island of gene is necessary for COX-2 expression in human gastric cancer. The expression status of COX-2 may provide theoretical basis for COX-2 targeting gastric cancer treatments.
authors.affiliation: Digestive Department, Xinhua Hospital, Shanghai Second Medical University, 1665 Kongjiang Road, Shanghai 200092, China.
authors.forename: Bao-Can
authors.initials: BC
authors.lastname: Wang
authors.forename: Chang-Qing
authors.initials: CQ
authors.lastname: Guo
authors.forename: Chao
authors.initials: C
authors.lastname: Sun
authors.forename: Qiao-Ling
authors.initials: QL
authors.lastname: Sun
authors.forename: Guo-Yong
authors.initials: GY
authors.lastname: Liu
authors.forename: Ding-Guo
authors.initials: DG
authors.lastname: Li
mesh_terms: D000328:Adult; D000368:Aged; D018899:CpG Islands / Q000502:physiology; D051546:Cyclooxygenase 2; D019175:DNA Methylation; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008565:Membrane Proteins; D008875:Middle Aged; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics*; D013274:Stomach Neoplasms / Q000235:genetics* / Q000503:physiopathology*
chemical_list: D008565:Membrane Proteins; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases