title: Suppression of RelA/p65 nuclear translocation independent of IkappaB-alpha degradation by cyclooxygenase-2 inhibitor in gastric cancer.
abstract: Selective cyclooxygenase-2 (COX-2) inhibitors are promising anti-inflammatory drugs with potential antitumor activities. The nuclear factor-kappa B (NF-kappaB) family of proteins is important transcriptional regulators of genes involved in immunity, inflammation, and carcinogenesis. In the present study, we investigated whether and by which molecular mechanism the selective COX-2 inhibitors inhibit NF-kappaB activation in gastric cancer. The effects of SC236 and its derivative, but devoid of COX-2 enzyme inhibition activity on NF-kappaB signaling, were evaluated using electromobility shift, transfection, and reporter gene assay. The translocation of RelA/p65 was investigated using Western blotting and immunocytochemistry. We showed that SC236 suppressed NF-kappaB-mediated gene transcription and binding activity in gastric cancer. This effect occurred through a mechanism independent of cyclooxygenase activity and prostaglandin synthesis. Furthermore, unlike aspirin, SC236 affected neither the phosphorylation, degradation, nor expression of IkappaB-alpha, suggesting that the effects of SC236 are independent of IKK activity and IkappaB-alpha gene transcription. Instead, SC236 worked directly through suppressing nuclear translocation of RelA/p65. It is possible that SC236 directly targets proteins that facilitate the nuclear translocation of NF-kappaB. Our study suggests an important molecular mechanism by which COX-2 inhibitors reduce inflammation and suppress carcinogenesis in gastrointestinal tract.
authors.affiliation: Department of Medicine, Unoversity of Hong Kong, Hong Kong, Republic of China. bcywong@hku.hk
authors.forename: Benjamin Chun Yu
authors.initials: BC
authors.lastname: Wong
authors.forename: Xiao hua
authors.initials: Xh
authors.lastname: Jiang
authors.forename: Xiao Ming
authors.initials: XM
authors.lastname: Fan
authors.forename: Marie Chia Mi
authors.initials: MC
authors.lastname: Lin
authors.forename: Shi Hu
authors.initials: SH
authors.lastname: Jiang
authors.forename: Shiu Kum
authors.initials: SK
authors.lastname: Lam
authors.forename: Hsiang Fu
authors.initials: HF
authors.lastname: Kung
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects*; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D001241:Aspirin / Q000494:pharmacology; D003110:Colonic Neoplasms / Q000473:pathology*; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D004273:DNA, Neoplasm / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D051550:I-kappa B Kinase; D020672:I-kappa B Proteins / Q000235:genetics / Q000378:metabolism; D007527:Isoenzymes / Q000037:antagonists & inhibitors*; D008565:Membrane Proteins; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors*; D010766:Phosphorylation / Q000187:drug effects; D011451:Prostaglandin-Endoperoxide Synthases; D011485:Protein Binding / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology*; D013274:Stomach Neoplasms / Q000473:pathology*; D013449:Sulfonamides / Q000494:pharmacology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D051996:Transcription Factor RelA; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D000096926:Benzenesulfonamides
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D016588:Anticarcinogenic Agents; D001241:Aspirin; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D004273:DNA, Neoplasm; D051550:I-kappa B Kinase; D020672:I-kappa B Proteins; D007527:Isoenzymes; D008565:Membrane Proteins; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B; D009363:Neoplasm Proteins; D011451:Prostaglandin-Endoperoxide Synthases; D017346:Protein Serine-Threonine Kinases; D011720:Pyrazoles; D013449:Sulfonamides; D013755:Tetradecanoylphorbol Acetate; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; C119130:4-(5-(4-chlorophenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl)benzenesulfonamide; D000096926:Benzenesulfonamides; C000606204:NFKBIA protein, human; C496540:PTGS2 protein, human; C496559:CHUK protein, human; C496560:IKBKB protein, human; C496565:IKBKE protein, human