title: Essential role of mitogen-activated protein kinase pathway and c-Jun induction in epidermal growth factor-induced gene expression of human 12-lipoxygenase.
abstract: The role of mitogen-activated protein kinase signaling and the transcription factor c-Jun in epidermal growth factor (EGF)-induced expression of 12-lipoxygenase in human epidermoid carcinoma A431 cells was studied. EGF increased the activation of extracellular signal-regulated kinase (ERK) and c-Jun amino terminal kinase (JNK) in a time-dependent manner. Treatment of the cells with an mitogen-activated protein kinase kinase inhibitor, PD098059 (30 microM), inhibited the EGF- and pSV2ras-induced expression of 12-lipoxygenase mRNA. Transfection of the cells with Ras, ERK2, Rac, JNK dominant negative mutants pMMrasDN, K52R ERK2, RacN17, and mJNK all inhibited the EGF-induced promoter activation of the 12-lipoxygenase gene. EGF induced the expression of c-Jun and the activity of transcription factor activator protein 1 in cells, and these effects were blocked by the treatment with K52R ERK2 and mJNK. Overexpression of c-Jun increased the expression of 12-lipoxygenase mRNA and enzyme activity. Furthermore, the Sp1-binding sites in the promoter region of the 12-lipoxygenase gene were requisite for c-Jun response, which was similar to that previously observed in EGF response. The results indicate that the EGF-induced expression of 12-lipoxygenase in A431 cells was mediated through the Ras-ERK and Ras-Rac-JNK signal pathways. Subsequent induction of c-Jun led by ERK and JNK activation was essential for this EGF response.
authors.affiliation: Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
authors.forename: B K
authors.initials: BK
authors.lastname: Chen
authors.forename: H C
authors.initials: HC
authors.lastname: Kung
authors.forename: T Y
authors.initials: TY
authors.lastname: Tsai
authors.forename: W C
authors.initials: WC
authors.lastname: Chang
mesh_terms: D001092:Arachidonate 12-Lipoxygenase / Q000096:biosynthesis / Q000235:genetics*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000502:physiology*; D005419:Flavonoids / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D011905:Genes, ras / Q000502:physiology; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020935:MAP Kinase Signaling System; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D009154:Mutation; D011401:Promoter Regions, Genetic; D016755:Proto-Oncogene Proteins c-jun / Q000096:biosynthesis* / Q000502:physiology; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured; D020744:rac GTP-Binding Proteins / Q000502:physiology
chemical_list: D004791:Enzyme Inhibitors; D005419:Flavonoids; D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1; D004815:Epidermal Growth Factor; D001092:Arachidonate 12-Lipoxygenase; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; D020744:rac GTP-Binding Proteins; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one