title: Ketoconazole suppresses prostaglandin E(2)-induced cyclooxygenase-2 expression in human epidermoid carcinoma A-431 cells.
abstract: Cyclooxygenase-2 is a key enzyme in the conversion of arachidonic acid to prostaglandins. The overexpression of cyclooxygenase-2 has been reported in skin cancer cells, and may be involved in carcinogenesis. Prostaglandin E2, the end product of cyclooxygenase-2-induced catalysis, autoamplifies the cyclooxygenase-2 expression. It is suggested that an anti-mycotic drug, ketoconazole may inhibit carcinogenesis. We herein investigated if ketoconazole may inhibit prostaglandin E2-induced cyclooxygenase-2 expression in human epidermoid carcinoma A-431 cells. Ketoconazole suppressed prostaglandin E2-induced cyclooxygenase-2 protein and mRNA expression and promoter activation in A-431; the suppressive effects of ketoconazole were counteracted by cyclic adenosine monophosphate analog. Analyses using deleted or mutated cyclooxygenase-2 promoters revealed that cyclic adenosine monophosphate response element (- 59 to - 53 bp) on the promoter was involved in prostaglandin E2-induced stimulation and ketoconazole-induced inhibition of the promoter activity. Electrophoretic mobility shift assays indicated that cyclic adenosine monophosphate response element binding protein and activating transcription factor-1 may constitutively bind to cyclic adenosine monophosphate response element on cyclooxygenase-2 promoter. Prostaglandin E2 increased the proportion of phosphorylated forms among total bound cyclic adenosine monophosphate response element binding protein/activating transcription factor-1, and the effect was suppressed by ketoconazole. Prostaglandin E2 induced the phosphorylation of cyclic adenosine monophosphate response element binding protein and activating transcription factor-1, and the phosphorylation was suppressed by cyclic adenosine monophosphate-dependent protein kinase (protein kinase A) inhibitor, indicating protein kinase A-mediated phosphorylation. Ketoconazole suppressed the prostaglandin E2-induced phosphorylation of cyclic adenosine monophosphate response element binding protein/activating transcription factor-1. Prostaglandin E2 increased intracellular cyclic adenosine monophosphate level by activating adenylate cyclase in A-431, and the increase was suppressed by ketoconazole. These results suggest that ketoconazole may suppress prostaglandin E2-induced cyclooxygenase-2 expression by inhibiting the cyclic adenosine monophosphate signal in A-431, and stress its anti-cancer effect.
authors.affiliation: Department of Dermatology, Teikyo University, School of Medicine, 11-1 Kaga-2, Itabashi-Ku, Tokyo 173-8605, Japan. nmk@med.teikyo-u.ac.jp
authors.forename: Naoko
authors.initials: N
authors.lastname: Kanda
authors.forename: Shinichi
authors.initials: S
authors.lastname: Watanabe
mesh_terms: D051697:Activating Transcription Factor 1; D000262:Adenylyl Cyclases / Q000378:metabolism; D000935:Antifungal Agents / Q000494:pharmacology*; D002294:Carcinoma, Squamous Cell; D000242:Cyclic AMP / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D051546:Cyclooxygenase 2; D004268:DNA-Binding Proteins; D015232:Dinoprostone / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000235:genetics*; D007654:Ketoconazole / Q000494:pharmacology*; D008565:Membrane Proteins; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000187:drug effects; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D015398:Signal Transduction / Q000187:drug effects; D012878:Skin Neoplasms; D014157:Transcription Factors / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D051697:Activating Transcription Factor 1; D000935:Antifungal Agents; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D007527:Isoenzymes; D008565:Membrane Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D000242:Cyclic AMP; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D000262:Adenylyl Cyclases; D015232:Dinoprostone; D007654:Ketoconazole