title: Targeted inhibition of COX-2 expression by RNA interference suppresses tumor growth and potentiates chemosensitivity to cisplatin in human gastric cancer cells.
abstract: Although selective cyclooxygenase-2 (COX-2) inhibitors suppress cell proliferation in gastric cancer, it remains debatable whether their effect is mediated through COX-2 dependent or independent pathways. We investigated the effects of the targeted inhibition of COX-2 expression by small interfering RNA (siRNA) in human gastric cancer cells and compared it to the effects of treatment with a specific COX-2 inhibitor. COX-2 mRNA and proteins were significantly reduced by up to 80% on day 2 after COX-2 siRNA transfection to the gastric cancer cell line MKN45. Concentrations of prostaglandins E2 (PGE2) in the condition medium were also reduced to 30% after siRNA transfection. Transfection of COX-2 siRNA exhibited a more potent anti-proliferative effect on MKN45 cells than treatment with high-dose (100 microM) NS398. COX-2 siRNA also significantly reduced tumor growth in nude mice. While COX-2 siRNA transfection alone had no obvious pro-apoptotic effects, unlike low-dose (10 microM) NS398 it enhanced the apoptotic reaction of MKN45 cells to cisplatin therapy. In conclusion, our results demonstrate for the first time that COX-2 siRNA inhibits cell growth and enhances the chemosensitivity of gastric cancer cells. RNA interference may be a promising alternative to specific COX-2 inhibitors in the prevention and treatment of gastric cancer.
authors.affiliation: Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong, PR China.
authors.forename: Michael W Y
authors.initials: MW
authors.lastname: Chan
authors.forename: Christine Y P
authors.initials: CY
authors.lastname: Wong
authors.forename: Alfred S L
authors.initials: AS
authors.lastname: Cheng
authors.forename: Victor Y W
authors.initials: VY
authors.lastname: Chan
authors.forename: Ka K
authors.initials: KK
authors.lastname: Chan
authors.forename: Ka F
authors.initials: KF
authors.lastname: To
authors.forename: Francis K L
authors.initials: FK
authors.lastname: Chan
authors.forename: Joseph J Y
authors.initials: JJ
authors.lastname: Sung
authors.forename: Wai K
authors.initials: WK
authors.lastname: Leung
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000627:therapeutic use*; D051546:Cyclooxygenase 2 / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D010957:Plasmids; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics*; D013274:Stomach Neoplasms / Q000188:drug therapy / Q000473:pathology*
chemical_list: D000970:Antineoplastic Agents; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D051546:Cyclooxygenase 2; D002945:Cisplatin