title: Prostaglandin-endoperoxide H synthase-2 expression in human thyroid epithelium. Evidence for constitutive expression in vivo and in cultured KAT-50 cells.
abstract: Prostaglandin-endoperoxide H synthase (PGHS) (EC 1.14.99.1) expression was examined in human thyroid tissue and in KAT-50, a well differentiated human thyroid epithelial cell line. PGHS-1 is found constitutively expressed in most healthy tissues, whereas PGHS-2 is highly inducible and currently thought to be expressed, with few exceptions, only in diseased tissues. Surprisingly, PGHS-2 mRNA and protein were easily detected in normal thyroid tissue. KAT-50 cells express high levels of constitutive PGHS-2 mRNA and protein under basal culture conditions. Compounds usually associated with PGHS-2 induction, including interleukin-1beta (IL-1beta), phorbol 12-myristate 13-acetate, and serum transiently down-regulated PGHS-2 expression. Human PGHS-2 promoter constructs (-1840/+123 and -831/+123) fused to a luciferase reporter and transfected into untreated KAT-50 cells exhibited substantial activity. NS-398, a highly selective inhibitor of PGHS-2 could inhibit substantial basal prostaglandin E2 production. Exogenous IL-1 receptor antagonist or IL-1alpha neutralizing antibodies could attenuate constitutive PGHS-2 expression in KAT-50 cells, suggesting that endogenous IL-1alpha synthesis was driving PGHS-2 expression. Our findings suggest that normal thyroid epithelium expresses high constitutive levels of PGHS-2 in situ and in vitro and this enzyme is active in the generation of prostaglandin E2. Thus, unprovoked PGHS-2 expression might be considerably more widespread in healthy tissues than is currently believed.
authors.affiliation: Division of Molecular and Cellular Medicine, Department of Medicine, Albany Medical College and the Samuel S. Stratton Veterans Affairs Medical Center, Albany, New York 12208, USA.
authors.forename: T J
authors.initials: TJ
authors.lastname: Smith
authors.forename: T A
authors.initials: TA
authors.lastname: Jennings
authors.forename: D
authors.initials: D
authors.lastname: Sciaky
authors.forename: H J
authors.initials: HJ
authors.lastname: Cao
mesh_terms: D002460:Cell Line; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000378:metabolism; D015536:Down-Regulation; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006801:Humans; D007150:Immunohistochemistry; D007375:Interleukin-1 / Q000494:pharmacology; D007527:Isoenzymes / Q000235:genetics*; D008565:Membrane Proteins; D009578:Nitrobenzenes / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D017472:Receptors, Interleukin-1 / Q000037:antagonists & inhibitors; D013449:Sulfonamides / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013961:Thyroid Gland / Q000201:enzymology* / Q000473:pathology; D014162:Transfection
chemical_list: D007375:Interleukin-1; D007527:Isoenzymes; D008565:Membrane Proteins; D009578:Nitrobenzenes; D012333:RNA, Messenger; D017472:Receptors, Interleukin-1; D013449:Sulfonamides; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; C496511:PTGS1 protein, human; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D015232:Dinoprostone; D013755:Tetradecanoylphorbol Acetate