title: PGE2-mediated upregulation of iNOS in murine breast cancer cells through the activation of EP4 receptors.
abstract: We report here that endogenous prostaglandin E(2) (PGE(2)) resulting from cyclooxygenase (COX)-2 expression in a highly metastatic murine breast cancer cell line C3L5 upregulates IFN-gamma + LPS-induced nitric oxide (NO) synthase (iNOS) expression and NO production. This action of PGE(2) is mediated through the EP(4) receptor in a cAMP-dependent manner. Both nonselective and selective COX-2 inhibitors suppressed IFN-gamma + LPS-induced NO production, which was largely restored by exogenous PGE(2) or EP(4) receptor agonist PGE(1) alcohol. EP(4) antagonist AH-23848B inhibited NO production with a concomitant downregulation of iNOS mRNA in IFN-gamma + LPS-stimulated cells. cAMP dependence of NO production by cells under inducible conditions was demonstrated by the use of known modulators of intracellular cAMP. Since both COX-2 and iNOS are implicated in breast cancer progression, our findings of EP(4) receptor-mediated upregulation of iNOS in COX-2-expressing breast cancer cells suggest that blocking COX-2 and/or EP(4) may provide a simple therapeutic modality in this tumor model.
authors.affiliation: Department of Anatomy and Cell Biology, University of Western Ontario, London, Ontario, Canada.
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Timoshenko
authors.forename: Peeyush K
authors.initials: PK
authors.lastname: Lala
authors.forename: Chandan
authors.initials: C
authors.lastname: Chakraborty
mesh_terms: D000818:Animals; D000242:Cyclic AMP / Q000494:pharmacology; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D015232:Dinoprostone / Q000502:physiology*; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D007527:Isoenzymes / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008325:Mammary Neoplasms, Experimental / Q000201:enzymology* / Q000473:pathology; D008565:Membrane Proteins; D051379:Mice; D008809:Mice, Inbred C3H; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D011458:Prostaglandins E / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018078:Receptors, Prostaglandin E / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D058309:Receptors, Prostaglandin E, EP4 Subtype; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
chemical_list: D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D008070:Lipopolysaccharides; D008565:Membrane Proteins; C545650:PTGER4 protein, human; D011458:Prostaglandins E; C545651:Ptger4 protein, mouse; D012333:RNA, Messenger; D018078:Receptors, Prostaglandin E; D058309:Receptors, Prostaglandin E, EP4 Subtype; D009569:Nitric Oxide; D007371:Interferon-gamma; D000242:Cyclic AMP; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D015232:Dinoprostone