Department of Pediatrics, Section of Hematology/Oncology, University of Colorado School of Medicine, Aurora, CO, USA.
University of Colorado Hemophilia and Thrombosis Center, Aurora, CO, USA.
J Thromb Haemost. 2018 Feb;16(2):352-363. doi: 10.1111/jth.13875. Epub 2018 Jan 12.
Essentials Signaling by Gas6 through Tyro3/Axl/Mer receptors is essential for stable platelet aggregation. UNC2025 is a small molecule inhibitor of the Mer tyrosine kinase. UNC2025 decreases platelet activation in vitro and thrombus formation in vivo. UNC2025's anti-platelet effect is synergistic with inhibition of the ADP receptor, P2Y .
Background Growth arrest-specific protein 6 signals through the TAM (TYRO-3-AXL-MERTK) receptor family, mediating platelet activation and thrombus formation via activation of the aggregate-stabilizing α β integrin. Objective To describe the antithrombotic effects mediated by UNC2025, a small-molecule MERTK tyrosine kinase inhibitor. Methods MERTK phosphorylation and downstream signaling were assessed by immunoblotting. Light transmission aggregometry, flow cytometry and microfluidic analysis were used to evaluate the impact of MERTK inhibition on platelet activation and stability of aggregates in vitro. The effects of MERTK inhibition on arterial and venous thrombosis, platelet accumulation at microvascular injury sites and tail bleeding times were determined with murine models. The effects of combined treatment with ADP-P2Y pathway antagonists and UNC2025 were also evaluated. Results and Conclusions Treatment with UNC2025 inhibited MERTK phosphorylation and downstream activation of AKT and SRC, decreased platelet activation, and protected animals from pulmonary embolism and arterial thrombosis without increasing bleeding times. The antiplatelet effect of UNC2025 was enhanced in combination with ADP-P2Y pathway antagonists, and a greater than additive effect was observed when these two agents with different mechanisms of inhibition were coadministered. TAM kinase signaling represents a potential therapeutic target, as inhibition of this axis, especially in combination with ADP-P2Y pathway antagonism, mediates decreased platelet activation, aggregate stability, and thrombus formation, with less hemorrhagic potential than current treatment strategies. The data presented here also demonstrate antithrombotic activity mediated by UNC2025, a novel translational agent, and support the development of TAM kinase inhibitors for clinical applications.
Gas6 通过 Tyro3/Axl/Mer 受体的信号传导对于稳定的血小板聚集至关重要。UNC2025 是 Mer 酪氨酸激酶的小分子抑制剂。UNC2025 可减少体外血小板活化和体内血栓形成。UNC2025 的抗血小板作用与抑制 ADP 受体（P2Y ）协同作用。
背景：生长停滞特异性蛋白 6 通过 TAM（TYRO-3-AXL-MERTK）受体家族发出信号，通过激活稳定聚集的 αβ整合素来介导血小板激活和血栓形成。目的：描述 UNC2025 介导的抗血栓形成作用，UNC2025 是一种小分子 MERTK 酪氨酸激酶抑制剂。
通过免疫印迹评估 MERTK 磷酸化和下游信号转导。使用透光比浊法、流式细胞术和微流控分析评估 MERTK 抑制对体外血小板活化和聚集稳定性的影响。使用小鼠模型确定 MERTK 抑制对动脉和静脉血栓形成、微血管损伤部位血小板积聚和尾部出血时间的影响。还评估了 MERTK 抑制与 ADP-P2Y 通路拮抗剂联合治疗的效果。
UNC2025 治疗抑制了 MERTK 磷酸化及其下游 AKT 和 SRC 的激活，减少了血小板活化，并保护动物免受肺栓塞和动脉血栓形成的影响，而不会增加出血时间。UNC2025 与 ADP-P2Y 通路拮抗剂联合使用可增强其抗血小板作用，并且当这两种具有不同抑制机制的药物联合使用时，可观察到大于相加的作用。TAM 激酶信号转导代表一种潜在的治疗靶点，因为抑制该轴，特别是与 ADP-P2Y 通路拮抗作用联合使用，可介导血小板活化、聚集稳定性和血栓形成减少，其出血风险低于目前的治疗策略。这里呈现的数据还证明了 UNC2025（一种新型转化剂）介导的抗血栓形成活性，并支持 TAM 激酶抑制剂在临床应用中的开发。
