title: Promoter hypermethylation of cyclooxygenase-2 gene in esophageal squamous cell carcinoma.
abstract: Cyclooxygenase-2 (COX-2) is overexpressed in various types of human malignancies including esophageal squamous cell carcinoma (ESCC). However, a subset of ESCC either do not express COX-2 or show low level of expression. It is well established that promoter methylation is a major mechanism that mediates transcriptional silencing of COX-2 in gastric and colorectal cancer, but the data on ESCC are very limited. In this study, we attempted to determine whether COX-2 expression was also regulated by promoter methylation in human ESCC cell lines. We examined the methylation status of the COX-2 promoter in five human ESCC cell lines (EC109, EC9706, KYSE 410, KYSE 150, TE-1) using bisulfite sequencing analysis. Western blot analysis was used to determine COX-2 expression. Quantitative real-time polymerase chain reaction was used to determine COX-2 mRNA level. Prostaglandin (PG) E(2) was detected by ELISA. The promoter was densely methylated in TE-1 and KYSE 150, which had a low level of COX-2 expression and less methylated in other three cell lines (EC109, EC9706, KYSE 410), with high level of COX-2 expression. Treatment with 5-aza-deoxycytidine (5-aza-DC), a DNA methyltransferase inhibitor, demethylated the promoter and upregulated COX-2 expression, as well as PGE(2) production in TE-1 and KYSE 150. However, no such effects were observed in EC109. COX-2 protein was negative, but mRNA was positive in TE-1. After treatment with 5-aza-DC, both COX-2 mRNA and protein level had increased. These findings suggest that the promoter methylation may be one of the mechanisms that regulate COX-2 expression in ESCC.
authors.affiliation: Department of Gastroenterology, Qingdao Municipal Hospital(East), Medical College of Qingdao University, Qingdao City, Shandong, PR China.
authors.forename: X Y
authors.initials: XY
authors.lastname: Meng
authors.forename: S T
authors.initials: ST
authors.lastname: Zhu
authors.forename: Y
authors.initials: Y
authors.lastname: Zong
authors.forename: Y J
authors.initials: YJ
authors.lastname: Wang
authors.forename: P
authors.initials: P
authors.lastname: Li
authors.forename: S T
authors.initials: ST
authors.lastname: Zhang
mesh_terms: D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D002294:Carcinoma, Squamous Cell / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D051546:Cyclooxygenase 2 / Q000235:genetics* / Q000378:metabolism; D019175:DNA Methylation / Q000187:drug effects / Q000235:genetics*; D000077209:Decitabine; D015232:Dinoprostone / Q000378:metabolism; D004938:Esophageal Neoplasms / Q000235:genetics* / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D006801:Humans; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism*; D017422:Sequence Analysis, DNA
chemical_list: D012333:RNA, Messenger; D000077209:Decitabine; D051546:Cyclooxygenase 2; D015232:Dinoprostone; D001374:Azacitidine