Inhibition of cellular action of thrombin by N3-cyclopropyl-7-[[4-(1-methylethyl)phenyl]methyl]-7H-pyrrolo[3, 2-f]quinazoline-1,3-diamine (SCH 79797), a nonpeptide thrombin receptor antagonist.
A growing body of evidence suggests an important contribution of the cellular actions of thrombin to thrombosis and restenosis following angioplasty. Recently we reported on SCH 79797 (N3-cyclopropyl-7-¿[4-(1-methylethyl)phenyl]methyl¿-7H-pyrrolo[3, 2-f]quinazoline-1,3-diamine) and its analogs as new potent, nonpeptide thrombin receptor antagonists. This study further characterizes the biochemical and pharmacological actions of pyrroloquinazoline inhibitors of protease activated receptor-1 (PAR-1) in human platelets and coronary artery smooth muscle cells (hCASMC). SCH 79797 and its N-methyl analog (SCH 203099) inhibited binding of a high-affinity thrombin receptor-activating peptide ([(3)H]haTRAP, Ala-Phe(p-F)-Arg-ChA-HArg-[(3)H]Tyr-NH(2)) to PAR-1 with IC(50) values of 70 and 45 nM, respectively. SCH 79797 inhibited [(3)H]haTRAP binding in a competitive manner. SCH 79797 and SCH 203099 inhibited alpha-thrombin- and haTRAP-induced aggregation of human platelets, but did not inhibit human platelet aggregation induced by the tethered ligand agonist for protease-activated receptor-4 (PAR-4), gamma-thrombin, ADP, or collagen. SCH 203099 inhibited surface expression of P-selectin induced by haTRAP and thrombin, and it did not increase P-selectin expression or prevent thrombin cleavage of the receptor. Thrombin and TFLLRNPNDK-NH(2) (TK), a PAR-1-selective agonist, produced transient increases in cytosolic free Ca(2+) concentration ([Ca(2+)](i)) in hCASMC. This increase in [Ca(2+)](i) was inhibited effectively by SCH 79797. However, the Ca(2+) transients induced by SLIGKV-NH(2,) a PAR-2-selective agonist, were not inhibited by SCH 79797. Thrombin- and TK-stimulated [(3)H]thymidine incorporation also was inhibited completely by SCH 79797. The results of this study demonstrate that SCH 79797 and SCH 203099 are potent, selective antagonists of PAR-1 in human platelets and hCASMC. These data also suggest that the thrombin stimulation of Ca(2+) transients and mitogenesis in hCASMC is mediated primarily through activation of PAR-1.
Ahn
H S
HS
Schering-Plough Research Institute, Kenilworth, NJ, 07033, USA. ho-sam.ahn@spcorp.com
Foster
C
C
Boykow
G
G
Stamford
A
A
Manna
M
M
Graziano
M
M
D051017:Apoptosis Regulatory Proteins; D001426:Bacterial Proteins; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002352:Carrier Proteins / Q000819:agonists; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis / Q000187:drug effects; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D019007:P-Selectin / Q000096:biosynthesis; D010446:Peptide Fragments / Q000378:metabolism; D010974:Platelet Aggregation / Q000187:drug effects; D011758:Pyrroles / Q000378:metabolism* / Q000494:pharmacology*; D011799:Quinazolines / Q000378:metabolism* / Q000494:pharmacology*; D016601:RNA-Binding Proteins / Q000037:antagonists & inhibitors; D044463:Receptor, PAR-1; D018179:Receptors, Thrombin / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013917:Thrombin / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013936:Thymidine / Q000378:metabolism; D014157:Transcription Factors / Q000037:antagonists & inhibitors; D014214:Triallate
D051017:Apoptosis Regulatory Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; C079092:MtrB protein, Bacteria; C415424:N3-cyclopropyl-7-((4-(1-methylethyl)phenyl)methyl)-7H-pyrrolo(3, 2-f)quinazoline-1,3-diamine; D019007:P-Selectin; D010446:Peptide Fragments; D011758:Pyrroles; D011799:Quinazolines; D016601:RNA-Binding Proteins; D044463:Receptor, PAR-1; D018179:Receptors, Thrombin; D014157:Transcription Factors; C101296:prostate apoptosis response-4 protein; D004247:DNA; D014214:Triallate; D013917:Thrombin; D002118:Calcium; D013936:Thymidine