Inhibition of Collagen Related Peptide Induced Platelet Activation and Apoptosis by Ceritinib

Background/aims: The anaplastic lymphoma (tyrosine) kinase (ALK) inhibitor ceritinib triggers Apoptosis of tumor cells and eryptosis of erythrocytes. Blood platelets may similarly enter a state resembling Apoptosis, which could be triggered by activation with collagen related peptide (CRP). CRP-induced platelet Apoptosis is characterized by cell membrane scrambling with phosphatidylserine exposure to the platelet surface and cell shrinkage, preceded by externalization of Ca2+ channel Orai1, increase of cytosolic Ca2+-activity ([Ca2+]i), formation of Reactive Oxygen Species (ROS), and Caspase activation. The present study explored whether ceritinib triggers platelet Apoptosis and/or modifies the CRP induced Apoptosis.

Methods: Platelets isolated from wild-type mice were exposed for 30 minutes to ceritinib (1.5 µg/ml) without or with 2.5 - 15 min pretreatment with CRP (2 µg/ml or 5 µg/ml). Flow cytometry was employed to estimate cytosolic Ca2+-activity ([Ca2+]i) from Fluo-3 fluorescence, ROS abundance from 2',7'-dichlorodihydrofluorescein diacetate fluorescence, platelet degranulation from P-selectin abundance, Integrin activation from αIIbβ3 Integrin abundance, Caspase activity utilizing an Active Caspase-3 Staining kit, phosphatidylserine abundance from annexin-V-binding, platelet volume from forward scatter and aggregation utilizing staining with CD9-APC and CD9-PE.

Results: In the absence of CRP, ceritinib slightly, but significantly decreased [Ca2+]i without significantly modifying the other measured parameters. CRP significantly increased [Ca2+]i, ROS abundance, P-selectin abundance, activated αIIbβ3 Integrin, annexin-V-binding, Caspase activity as well as aggregation and decreased cell volume, all effects significantly blunted in the presence of ceritinib.

Conclusions: The present observations uncover a novel, unexpected effect of ceritinib, i.e. inhibition of CRP-induced platelet activation and Apoptosis.