title: Prostaglandin E2 induces cyclooxygenase-2 expression in human non-pigmented ciliary epithelial cells through activation of p38 and p42/44 mitogen-activated protein kinases.
abstract: Prostaglandins (PGs) have been implicated in lowering intraocular pressure (IOP). A possible role of cyclooxygenase-2 (COX-2) in this process was emphasized by findings showing impaired COX-2 expression in the non-pigmented ciliary epithelium (NPE) of patients with primary open-angle glaucoma. The present study investigates the effect of the major COX-2 product, PGE(2), on the expression of its synthesizing enzyme in human NPE cells (ODM-2). PGE(2) led to an increase of COX-2 mRNA and protein expression, whereas the expression of COX-1 remained unchanged. Upregulation of COX-2 expression by PGE(2) was accompanied by time-dependent phosphorylations of p38 mitogen-activated protein kinase (MAPK) and p42/44 MAPK, and was abrogated by inhibitors of both pathways. Moreover, PGE(2)-induced COX-2 expression was suppressed by the intracellular calcium chelator, BAPTA/AM, and the protein kinase C inhibitor bisindolylmaleimide II, whereas the protein kinase A inhibitor H-89 was inactive in this respect. Induction of COX-2 expression was also elicited by butaprost (EP(2) receptor agonist) and 11-deoxy PGE(1) (EP(2)/EP(4) receptor agonist), but not by EP(1)/EP(3) receptor agonists (17-phenyl-omega-trinor PGE(2), sulprostone). Consistent with these findings, the EP(1)/EP(2) receptor antagonist, AH-6809, and the selective EP(4) receptor antagonist, ONO-AE3-208, significantly reduced PGE(2)-induced COX-2 expression. Collectively, our results demonstrate that PGE(2) at physiologically relevant concentrations induces COX-2 expression in human NPE cells via activation of EP(2)- and EP(4) receptors and phosphorylation of p38 and p42/44 MAPKs. Positive feedback regulation of COX-2 may contribute to the production of outflow-facilitating PGs and consequently to regulation of IOP.
authors.affiliation: Department of Experimental and Clinical Pharmacology and Toxicology, Friedrich Alexander University Erlangen-Nürnberg, Fahrstrasse 17, D-91054 Erlangen, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Rösch
authors.forename: Robert
authors.initials: R
authors.lastname: Ramer
authors.forename: Kay
authors.initials: K
authors.lastname: Brune
authors.forename: Burkhard
authors.initials: B
authors.lastname: Hinz
mesh_terms: D002478:Cells, Cultured; D002924:Ciliary Body / Q000378:metabolism*; D051546:Cyclooxygenase 2 / Q000096:biosynthesis*; D015232:Dinoprostone / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004847:Epithelial Cells / Q000378:metabolism*; D019573:Epithelium, Corneal / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D008565:Membrane Proteins / Q000096:biosynthesis*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D008565:Membrane Proteins; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases; D015232:Dinoprostone