title: DG-041 inhibits the EP3 prostanoid receptor--a new target for inhibition of platelet function in atherothrombotic disease.
abstract: Receptors for prostanoids on platelets include the EP3 receptor for which the natural agonist is the inflammatory mediator prostaglandin E(2) (PGE(2)) produced in atherosclerotic plaques. EP3 is implicated in atherothrombosis and an EP3 antagonist might provide atherosclerotic lesion-specific antithrombotic therapy. DG-041 (2,3-dichlorothiophene-5-sulfonic acid, 3-[1-(2,4-dichlorobenzyl)-5-fluoro-3-methyl-1H-indol-7-yl]acryloylamide) is a direct-acting EP3 antagonist currently being evaluated in Phase 2 clinical trials. We have examined the contributions of EP3 to platelet function using the selective EP3 agonist sulprostone and also PGE(2), and determined the effects of DG-041 on these. Studies were in human platelet-rich plasma or whole blood and included aggregometry and flow cytometry. Sulprostone enhanced aggregation induced by primary agonists including collagen, TRAP, platelet activating factor, U46619, serotonin and adenosine diphosphate, and enhanced P-selectin expression and platelet-leukocyte conjugate formation. It inhibited adenylate cyclase (measured by vasodilator-stimulated phosphoprotein phosphorylation) and enhanced Ca(2+) mobilization. It potentiated platelet function even in the presence of aspirin and/or AR-C69931 (a P2Y(12) antagonist). DG-041 antagonized the effects of sulprostone on platelet function. The effect of PGE(2) on platelet aggregation depended on the nature of the agonist and the concentration of PGE(2) used as a consequence of both pro-aggregatory effects via EP3 and anti-aggregatory effects via other receptors. DG-041 potentiated the protective effects of PGE(2) on platelet aggregation by inhibiting the pro-aggregatory effect via EP3 stimulation. DG-041 remained effective in the presence of a P2Y(12) antagonist and aspirin. DG-041 warrants continued investigation as a potential agent for the treatment of atherothrombosis without inducing unwanted bleeding risk.
authors.affiliation: Department of Cardiovascular Medicine, University of Nottingham, Nottingham, UK. s.heptinstall@nottingham.ac.uk
authors.forename: Stan
authors.initials: S
authors.lastname: Heptinstall
authors.forename: David Iyu
authors.initials: DI
authors.lastname: Espinosa
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Manolopoulos
authors.forename: Jackie R
authors.initials: JR
authors.lastname: Glenn
authors.forename: Ann E
authors.initials: AE
authors.lastname: White
authors.forename: Andrew
authors.initials: A
authors.lastname: Johnson
authors.forename: Natalia
authors.initials: N
authors.lastname: Dovlatova
authors.forename: Sue C
authors.initials: SC
authors.lastname: Fox
authors.forename: Jane A
authors.initials: JA
authors.lastname: May
authors.forename: David
authors.initials: D
authors.lastname: Hermann
authors.forename: Olafur
authors.initials: O
authors.lastname: Magnusson
authors.forename: Kari
authors.initials: K
authors.lastname: Stefansson
authors.forename: Dan
authors.initials: D
authors.lastname: Hartman
authors.forename: Mark
authors.initials: M
authors.lastname: Gurney
mesh_terms: D000178:Acrylamides / Q000494:pharmacology* / Q000627:therapeutic use; D000249:Adenosine Monophosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D001241:Aspirin / Q000494:pharmacology; D050197:Atherosclerosis / Q000188:drug therapy*; D001792:Blood Platelets / Q000166:cytology / Q000187:drug effects; D002478:Cells, Cultured; D015232:Dinoprostone / Q000031:analogs & derivatives / Q000494:pharmacology; D004347:Drug Interactions; D006801:Humans; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D058919:Purinergic P2 Receptor Antagonists; D018078:Receptors, Prostaglandin E / Q000037:antagonists & inhibitors* / Q000502:physiology*; D058308:Receptors, Prostaglandin E, EP3 Subtype; D058925:Receptors, Purinergic P2Y12; D013450:Sulfones / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: C531572:3-(1-((2,4-dichlorophenyl)methyl)-5-fluoro-3-methyl-1H-indol-7-yl)-N-((4,5-dichloro-2-thienyl)sulfonyl)-2-propenamide; D000178:Acrylamides; C548576:P2RY12 protein, human; C545647:PTGER3 protein, human; D010975:Platelet Aggregation Inhibitors; D058919:Purinergic P2 Receptor Antagonists; D018078:Receptors, Prostaglandin E; D058308:Receptors, Prostaglandin E, EP3 Subtype; D058925:Receptors, Purinergic P2Y12; D013450:Sulfones; D000249:Adenosine Monophosphate; C016767:sulprostone; C117446:cangrelor; D015232:Dinoprostone; D001241:Aspirin