ABSTRACT
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, P2Y12 . SUMMARY: 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 αIIb ß3 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-P2Y1&12 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-P2Y1&12 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.
Subject(s)
Adenine/analogs & derivatives , Blood Platelets/drug effects , Piperazines/pharmacology , Platelet Activation/drug effects , Platelet Aggregation Inhibitors/pharmacology , Protein Kinase Inhibitors/pharmacology , Pulmonary Embolism/prevention & control , Thrombosis/prevention & control , c-Mer Tyrosine Kinase/antagonists & inhibitors , Adenine/pharmacokinetics , Adenine/pharmacology , Animals , Blood Platelets/enzymology , Disease Models, Animal , Drug Synergism , Drug Therapy, Combination , Female , Humans , Intercellular Signaling Peptides and Proteins/metabolism , Male , Mice, Inbred C57BL , Phosphorylation , Piperazines/pharmacokinetics , Platelet Aggregation/drug effects , Platelet Aggregation Inhibitors/pharmacokinetics , Platelet Glycoprotein GPIIb-IIIa Complex/metabolism , Protein Kinase Inhibitors/pharmacokinetics , Proto-Oncogene Proteins/metabolism , Pulmonary Embolism/blood , Pulmonary Embolism/enzymology , Purinergic P2Y Receptor Antagonists/pharmacology , Receptor Protein-Tyrosine Kinases/metabolism , Signal Transduction/drug effects , Thrombosis/blood , Thrombosis/enzymology , c-Mer Tyrosine Kinase/metabolism , Axl Receptor Tyrosine KinaseABSTRACT
Cellular senescence is an initial barrier for carcinogenesis. However, the signaling mechanisms that trigger cellular senescence are incompletely understood, particularly in vivo. Here we identify Wnt7a as a novel upstream inducer of cellular senescence. In two different mouse strains (C57Bl/6J and FVB/NJ), we show that the loss of Wnt7a is a major contributing factor for increased lung tumorigenesis owing to reduced cellular senescence, and not reduced apoptosis, or autophagy. Wnt7a-null mice under de novo conditions and in both the strains display E-cadherin-to-N-cadherin switch, reduced expression of cellular senescence markers and reduced expression of senescence-associated secretory phenotype, indicating a genetic predisposition of these mice to increased carcinogen-induced lung tumorigenesis. Interestingly, Wnt7a induced an alternate senescence pathway, which was independent of ß-catenin, and distinct from that of classical oncogene-induced senescence mediated by the well-known p16(INK4a) and p19(ARF) pathways. Mechanistically, Wnt7a induced cellular senescence via inactivation of S-phase kinase-associated protein 2, an important alternate regulator of cellular senescence. Additionally, we identified Iloprost, a prostacyclin analog, which initiates downstream signaling cascades similar to that of Wnt7a, as a novel inducer of cellular senescence, presenting potential future clinical translational strategies. Thus pro-senescence therapies using either Wnt7a or its mimic, Iloprost, might represent a new class of therapeutic treatments for lung cancer.
Subject(s)
Cellular Senescence , Lung Neoplasms/pathology , Tumor Suppressor Proteins/physiology , Wnt Proteins/physiology , beta Catenin/physiology , Animals , Cell Line, Tumor , Cellular Senescence/drug effects , Humans , Iloprost/pharmacology , Mice , Mice, Inbred C57BL , S-Phase Kinase-Associated Proteins/physiology , Signal TransductionABSTRACT
The effect of biofeedback-assisted relaxation on cell-mediated immunity, cortisol, and white blood cell count was investigated in healthy adults under low-stress conditions. Fourteen subjects were trained with biofeedback-assisted relaxation for 4 weeks, while 17 subjects were controls. The group trained in relaxation techniques showed increased blastogenesis, decreased white blood cell count, due to decreased neutrophils, and no change in cortisol in comparison to the control group. Subjects with lower initial anxiety scores and forehead muscle tension levels showed larger increases in blastogenesis and larger decreases in neutrophils than subjects with higher initial anxiety and muscle tension levels.
Subject(s)
Arousal/physiology , Biofeedback, Psychology/physiology , Hydrocortisone/blood , Immunity, Cellular/immunology , Leukocyte Count , Muscle Relaxation/immunology , Adult , Female , Humans , Immunocompetence/immunology , Lymphocyte Activation/immunology , Male , PsychoneuroimmunologyABSTRACT
The usefulness of biofeedback-assisted relaxation as an adjunct or substitute for pharmacotherapy in essential hypertension can be enhanced if the effects are shown to persist after formal treatment has ended. Patients with essential hypertension successfully treated with biofeedback-assisted relaxation were recalled for follow-up yearly after the termination of treatment. Twenty-six of 40 patients met the BP criterion for success. At one-, two-, and three-year follow-up, 31%, 38%, and 27% of the successful completers continued to meet the criterion for success. The pretreatment-posttreatment decreases in BP were accompanied by decreases in forehead muscle tension and urinary cortisol. Forehead muscle tension, urinary cortisol, and anxiety levels were significantly lower than pretreatment one year after the end of treatment. Self-report data were used to assess continued relaxation practice. No relationship was found between practice and any other dependent measure. It appears that some patients trained in biofeedback-assisted relaxation can maintain lowered blood pressure, muscle tension, anxiety, and cortisol levels over the long term; however, the role of relaxation practice in maintaining these lowered levels remains unclear.
