The P2Y12 Antagonists, 2MeSAMP and Cangrelor, Inhibit Platelet Activation through P2Y12/Gi-Dependent Mechanism

• Published in: PloS one 2012-12, Vol.7 (12), p.e51037
• Main Authors: Xiang, Binggang, Zhang, Guoying, Ren, Hongmei, Sunkara, Manjula, Morris, Andrew J., Gartner, T. Kent, Smyth, Susan S., Li, Zhenyu
• Format: Article
• Language: English
• Subjects: Activation; Adenosine; Adenosine diphosphate; Agglomeration; AKT protein; Biology; Blood platelets; Calcium mobilization; Clinical trials; Cyclic AMP; Forskolin; Inhibition; Kinases; Laboratory animals; Medical research; Medicine; Mice; Phosphorylation; Physiology; Platelet aggregation; Platelets; Proteins; Receptors; Salts; Thromboembolism; Thrombosis; Vasodilator-stimulated phosphoprotein
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0051037

Background ADP is an important physiological agonist that induces integrin activation and platelet aggregation through its receptors P2Y1 (Gαq-coupled) and P2Y12 (Gαi-coupled). P2Y12 plays a critical role in platelet activation and thrombosis. Adenosine-based P2Y12 antagonists, 2-methylthioadenosine 5′-monophosphate triethylammonium salt hydrate (2MeSAMP) and Cangrelor (AR-C69931MX) have been widely used to demonstrate the role of P2Y12 in platelet function. Cangrelor is being evaluated in clinical trials of thrombotic diseases. However, a recent study reported that both 2MeSAMP and Cangrelor raise intra-platelet cAMP levels and inhibit platelet aggregation through a P2Y12-independent mechanism. Methodology/Principal Findings The present work, using P2Y12 deficient mice, sought to clarify previous conflicting reports and to elucidate the mechanisms by which 2MeSAMP and Cangrelor inhibit platelet activation and thrombosis. 2MeSAMP and Cangrelor inhibited aggregation and ATP release of wild-type but not P2Y12 deficient platelets. 2MeSAMP and Cangrelor neither raised intracellular cAMP concentrations nor induced phosphorylation of vasodilator-stimulated phosphoprotein (VASP) in washed human or mouse platelets. Furthermore, unlike the activators (PGI2 and forskolin) of the cAMP pathway, 2MeSAMP and Cangrelor failed to inhibit Ca2+ mobilization, Akt phosphorylation, and Rap1b activation in P2Y12 deficient platelets. Importantly, while injection of Cangrelor inhibited thrombus formation in a FeCl3-induced thrombosis model in wild-type mice, it failed to affect thrombus formation in P2Y12 deficient mice. Conclusions These data together demonstrate that 2MeSAMP and Cangrelor inhibit platelet function through the P2Y12-dependent mechanism both in vitro and in vivo.