title: Essential role of c-Jun induction and coactivator p300 in epidermal growth factor-induced gene expression of cyclooxygenase-2 in human epidermoid carcinoma A431 cells.
abstract: Cyclooxygenase-2 (COX-2) is an inducible enzyme responsible for high-level prostaglandin production during inflammation and carcinogenesis. In this study, the transcriptional regulation of COX-2 expression induced by epidermal growth factor (EGF) in human epidermoid carcinoma A431 cells was studied. EGF treatment induced the expression of COX-2 mRNA, protein, promoter and enzyme activity in a time-dependent manner. EGF-induced COX-2 promoter activity was inhibited by overexpression of the dominant-negative forms of Ras and ERK2. Induction of COX-2 and c-Jun by EGF was completely suppressed by MEK inhibitor combined with JNK inhibitor. Analysis of the COX-2 promoter binding proteins by gel mobility shift assay and DNA affinity precipitation assay revealed that c-Jun and p300 binding to CRE/E-box site were responsible for the EGF-induced COX-2 gene transcription. Overexpression of p300 significantly enhanced COX-2 promoter activity in cells overexpressed of c-Jun or treated with EGF. EGF- and c-Jun-induced transcription of COX-2 promoter was repressed by cotransfection of E1A in a dose-dependent manner. All together, these results indicated that the EGF-induced expression of COX-2 in A431 cells was mediated through the Ras-ERK/JNK signaling pathway, and subsequent induction of c-Jun following MAPK activation, in cooperation with coactivator p300, was required for the EGF response.
authors.affiliation: Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Lei-Chin
authors.initials: LC
authors.lastname: Chen
authors.forename: Ben-Kuen
authors.initials: BK
authors.lastname: Chen
authors.forename: Jia-Ming
authors.initials: JM
authors.lastname: Chang
authors.forename: Wen-Chang
authors.initials: WC
authors.lastname: Chang
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000201:enzymology* / Q000473:pathology; D051546:Cyclooxygenase 2; D024202:Electrophoretic Mobility Shift Assay; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D015870:Gene Expression; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D007527:Isoenzymes / Q000235:genetics* / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020935:MAP Kinase Signaling System; D008565:Membrane Proteins; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000502:physiology*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics* / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000502:physiology*; D017384:Sequence Deletion; D015534:Trans-Activators / Q000502:physiology*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured; D020744:rac GTP-Binding Proteins / Q000502:physiology
chemical_list: D004791:Enzyme Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D009687:Nuclear Proteins; D016755:Proto-Oncogene Proteins c-jun; D015534:Trans-Activators; D004815:Epidermal Growth Factor; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; D020744:rac GTP-Binding Proteins