Objective:To investigate the role of platelet-derived zyxin in promoting tumor migration by platelets.Methods:The gene expression profile of platelets was analyzed from cancer patients by using the GEO database.Isolated platelets from wild-type(WT)and Zyx-/-mice were co-cultured with B16F10 cells labeled with green fluorescence to investigate the influence of zyxin deficiency on tumor cell migration,invasion,and wound healing.Optical microscopy was employed to evaluate the impact of zyxin deficiency on epithelial-mesenchymal transition(EMT)in B16F10 cells induced by platelets.Employing specific markers to label platelets,fluorescence confocal microscopy was utilized to investigate the impact of platelet-derived zyxin on the binding between tumor cells and platelets.And an aggregometer was employed to observe the influence of zyxin deficiency on tumor cell-induced platelet aggregation.Results:Compared to platelets from healthy volunteers,zyxin was upregulated in platelets from cancer patients.Zyx-/-mouse platelets exhibited a significant reduction in tumor cell invasion and migration,impaired wound healing,and delayed tumor cell EMT compared to WT mouse platelets.Additionally,zyxin deficiency attenuated the interaction between platelets and tumor cells,and diminished the capacity for tumor cell-induced platelet aggregation.Conclusion:Platelet-derived zyxin deficiency diminishes platelet-tumor cell interactions and weakens the ability of tumor cell-induced platelet aggregation,ultimately suppressing tumor cell migration.

Objective:To investigate the effects of oridonin on platelet function and related mechanisms.Methods:Washed platelets from healthy adults and mice were incubated with different concentrations of oridonin(2.5,5 and 10μmol/L)in vitro.The surface expression level of P-selectin and the activation of integrin αⅡbβ3 in platelets were detected by flow cytometry,and the aggregation ability of platelets under the stimulation by various agonists was detected by light transmission aggregometry.The expression of P-AKT(Ser473)was detected by protein immunoblotting.Arterial thrombosis model was established in mice with mesenteric injury induced by ferric chloride,and tail hemorrhage model was established by cutting off the tail of mice.The effect of intraperitoneal injection of oridonin(10 mg/kg)on thrombosis and haemostasis was tested.Results:Oridonin inhibited platelet P-selectin expression and integrin αⅡbβ3 activation.In the presence of different stimulants,oridonin inhibited platelet aggregation in a concentration-dependent manner.The phosphorylation level of AKT Ser473 was reduced in the groups treated with different concentrations of oridonin.Oridonin significantly prolonged the time of mesenteric artery thrombosis in mice,but did not affect the tail bleeding time.Conclusion:Oridonin inhibits platelet activation,aggregation,and thrombosis by inhibiting AKT phosphorylation,and may be used as a potential antiplatelet drug.

Objective:To investigate the role of platelet-derived zyxin in promoting tumor migration by platelets.Methods:The gene expression profile of platelets was analyzed from cancer patients by using the GEO database.Isolated platelets from wild-type(WT)and Zyx-/-mice were co-cultured with B16F10 cells labeled with green fluorescence to investigate the influence of zyxin deficiency on tumor cell migration,invasion,and wound healing.Optical microscopy was employed to evaluate the impact of zyxin deficiency on epithelial-mesenchymal transition(EMT)in B16F10 cells induced by platelets.Employing specific markers to label platelets,fluorescence confocal microscopy was utilized to investigate the impact of platelet-derived zyxin on the binding between tumor cells and platelets.And an aggregometer was employed to observe the influence of zyxin deficiency on tumor cell-induced platelet aggregation.Results:Compared to platelets from healthy volunteers,zyxin was upregulated in platelets from cancer patients.Zyx-/-mouse platelets exhibited a significant reduction in tumor cell invasion and migration,impaired wound healing,and delayed tumor cell EMT compared to WT mouse platelets.Additionally,zyxin deficiency attenuated the interaction between platelets and tumor cells,and diminished the capacity for tumor cell-induced platelet aggregation.Conclusion:Platelet-derived zyxin deficiency diminishes platelet-tumor cell interactions and weakens the ability of tumor cell-induced platelet aggregation,ultimately suppressing tumor cell migration.

Objective:To investigate the factors affecting ferric chloride(FeCl3)-induced carotid artery thrombosis model experiment.Methods:After the common carotid artery was damaged by FeCl3,the injured vessels were dissected for fixation,embedding,frozen section,and then processed HE staining.The carotid thrombus area ratio was calculated.We examined the effect of FeCl3 concentration(5％,10％and 15％),reaction time(2,4 and 6 min),and recipient mouse age(4-5,6-8 and 10 weeks)on the formation and stability of arterial thrombosis model.The model was injected through the post-glomus venous plexus of mouse eyeball with 0.075 μg/g and 0.1 μg/g R300 to verify the accuracy of the FeCl3-induced model on thrombus formation by adjusting the platelet number.Results:HE staining showed that thrombus formation induced by 10％and 15％FeCl3 was more stable,dense and larger than 5％FeCl3-induced thrombosis.10％FeCl3 induced the formation of dense and large thrombosis after 4 and 6 minutes of vascular endothelium injury,while the thrombosis induced for 2 minutes were looser and smaller in area.Mouse age can not affect thrombus formation and stability,because there were no significant differences in the formation of dense thrombus and thrombus area induced by 10％FeCl3 among three different age groups of mice.Conclusion:Many factors affect the formation and stability of arterial thrombosis model induced by FeCl3.This optimal experimental conditions for construction of a stable carotid artery thrombosis model are 10％FeCl3,4 minutes for injury,and 6-8 week old mice.

Objective:To investigate how reactive oxygen species(ROS)regulates the signal transduction of platelet activation and apoptosis,and to explore the relationship between platelet activation and apoptosis.Methods:Platelets were directly stimulated with thrombin or pretreated with ROS inhibitor N-acetylcysteine(NAC)before being stimulated with thrombin,and then flow cytometry was used to detect the effects of thrombin and NAC on P-selectin expression,αⅡbβ3 activation,mitochondrial membrane potential depolarization,phosphatidylserine(PS)externalization,ROS expression and platelet aggregation.Results:Thrombin could induce the production of ROS in platelets in a concentration-and time-dependent manner.0.01 U thrombin induced ROS-dependent high degree of integrin αⅡbβ3 activation,P-selectin expression,and platelet aggregation.The platelets induced by different concentration gradients of thrombin exhibited ROS-dependent mitochondrial membrane potential depolarization and PS externalization in platelets.After induction with thrombin for 30 min,the activation of integrin αⅡbβ3 in platelets reached its maximum level,and after 60 minutes,the depolarization of mitochondrial membrane potential in platelets reached its maximum level.However,the expression of P-selectin,depolarization of mitochondrial membrane potential,and platelet aggregation function were all inhibited to a certain extent when the platelets were pretreated with ROS inhibitor NAC and then induced with thrombin.Conclusion:When platelets are induced by thrombin,ROS first regulates the activation of platelets,and then regulates the apoptosis of platelets.Both platelet activation and apoptosis depend on the production of ROS in platelets,and the signals of activation and apoptosis occur orderly.Inhibiting the ROS signal in platelets can effectively inhibit the activation and apoptosis of platelets.

OBJECTIVE: To explore the effects of Ena/VASP gene family on the expression of glycoprotein (GP) Ib-IX complex in human megakaryoblastic leukemia Dami cells. METHODS: SiRNAs targeting Ena/VASP gene family were designed and synthesized to interfere Enah, EVL and VASP gene expression. When the siRNAs were transfected into Dami cells by using Lipofectamine^TM 2000 for 48 h, the expression of GPIb-IX complex was detected by quantitative real-time PCR, Western blot and flow cytometry. RESULTS: We successfully established siVASP , siEVL and si Enah Dami cell lines. And it was found that the expression of GPIb-IX complex had no evident reduction in siEVL or siVASP Dami cells at both mRNA and protein level, while the total protein and membrane protein of GPIb-IX complex were obviously reduced when Enah was knocked down. CONCLUSION Enah could affect the expression of GPIb-IX complex in human megakaryoblastic leukemia Dami cells, but the underlying mechanism still needs to be further explored.
Humans ; Cell Line ; Platelet Glycoprotein GPIb-IX Complex/metabolism* ; Leukemia/metabolism* ; Blood Platelets/metabolism*

BACKGROUND: Patients with atrial fibrillation (AF) and prior stroke history have a high risk of cardiovascular events despite anticoagulation therapy. It is unclear whether catheter ablation (CA) has further benefits in these patients. METHODS: AF patients with a previous history of stroke or systemic embolism (SE) from the prospective Chinese Atrial Fibrillation Registry study between August 2011 and December 2020 were included in the analysis. Patients were matched in a 1:1 ratio to CA or medical treatment (MT) based on propensity score. The primary outcome was a composite of all-cause death or ischemic stroke (IS)/SE. RESULTS: During a total of 4.1 ± 2.3 years of follow-up, the primary outcome occurred in 111 patients in the CA group (3.3 per 100 person-years) and in 229 patients in the MT group (5.7 per 100 person-years). The CA group had a lower risk of the primary outcome compared to the MT group [hazard ratio (HR) = 0.59, 95% CI: 0.47-0.74, P < 0.001]. There was a significant decreasing risk of all-cause mortality (HR = 0.43, 95% CI: 0.31-0.61, P < 0.001), IS/SE (HR = 0.73, 95% CI: 0.54-0.97, P = 0.033), cardiovascular mortality (HR = 0.32, 95% CI: 0.19-0.54, P < 0.001) and AF recurrence (HR = 0.33, 95% CI: 0.30-0.37, P < 0.001) in the CA group compared to that in the MT group. Sensitivity analysis generated consistent results when adjusting for time-dependent usage of anticoagulants. CONCLUSIONS In AF patients with a prior stroke history, CA was associated with a lower combined risk of all-cause death or IS/SE. Further clinical trials are warranted to confirm the benefits of CA in these patients.

OBJECTIVE: To explore the regulation of mitochondria on platelet apoptosis and activation, and the relationship between platelet apoptosis and activation. METHODS: Platelets were isolated from peripheral venous blood of healthy volunteers. Cyclosporin A (CsA), which has a protective effect on the function of platelet mitochondria, BAPTA, which can chelate calcium ions across membranes in platelets, and NAC, an antioxidant that reduces the level of intracellular reactive oxygen species, were selected for coincubation with washed platelets, respectively. By flow cytometry, platelet aggregator was used to detect the changes of platelet mitochondrial function and platelet activation indexes after different interventions. RESULTS: H89, staurosporine, and A23187 led to platelet mitochondrial abnormalities, while CsA could effectively reverse the decline of platelet mitochondrial membrane potential caused by them. Antioxidant NAC could reverse platelet mitochondrial damage correspondingly, and completely reverse platelet shrinkage and phosphatidylserine eversion induced by H89. BAPTA, prostaglandin E1, acetylsalicylic acid and other inhibitors could not reverse the decline of platelet mitochondrial membrane potential. CONCLUSION Mitochondrial function plays an important role in platelet apoptosis and activation. Abnormal mitochondrial function causes the imbalance of reduction/oxidation state in platelets, which leads to platelet apoptosis. Platelet apoptosis and activation are independent signal processes.
Humans ; Blood Platelets/metabolism* ; Antioxidants/pharmacology* ; Mitochondria/physiology* ; Platelet Activation ; Apoptosis ; Membrane Potential, Mitochondrial ; Reactive Oxygen Species/pharmacology*

Unlike healthy, non-transformed cells, the proteostasis network of cancer cells is taxed to produce proteins involved in tumor development. Cancer cells have a higher dependency on molecular chaperones to maintain proteostasis. The chaperonin T-complex protein ring complex (TRiC) contains eight paralogous subunits (CCT1-8), and assists the folding of as many as 10% of cytosolic proteome. TRiC is essential for the progression of some cancers, but the roles of TRiC subunits in osteosarcoma remain to be explored. Here, we show that CCT4/TRiC is significantly correlated in human osteosarcoma, and plays a critical role in osteosarcoma cell survival. We identify a compound anticarin-β that can specifically bind to and inhibit CCT4. Anticarin-β shows higher selectivity in cancer cells than in normal cells. Mechanistically, anticarin-β potently impedes CCT4-mediated STAT3 maturation. Anticarin-β displays remarkable antitumor efficacy in orthotopic and patient-derived xenograft models of osteosarcoma. Collectively, our data uncover a key role of CCT4 in osteosarcoma, and propose a promising treatment strategy for osteosarcoma by disrupting CCT4 and proteostasis.

OBJECTIVE: To explore the main factors of platelet spreading and provide the foundation for related research. METHODS: Platelets (2×10⁷/ml) were draw from C57BL/6J mouse and kept at 22 ℃ for 1-2 hours. Platelets (2×10⁷/ml) were were allowed to adhere and spread on the fibrinogen-coated slides, after staining F-actin in platelets, the platelets were observed with the confocal microscopy. The effects of different concentrations of fibrinogen (10 μg/ml, 30 μg/ml, 100 μg/ml) and kinds of agonists ［thrombin(0.01,0.05,0.1 U/ml), ADP（5,10,20 μmol/L）, U46619（0.125,0.25,0.5 μmol/L）］ on platelets were analyzed. The platelet spreading was successful if the spreading rate was higher after treated with agonists. RESULTS: Compared to the group which coated with 10 μg/ml and 100 μg/ml fibrinogen, the platelet density is optimal when coated with 30 μg/ml fibrinogen. In addition, under the stimulation of thrombin, ADP and U46619, the spreading rate of platelets showed a certain concentration-dependent increasing. CONCLUSION The platelet spreading is easily influenced by various factors, the platelet spreading can be induced successfully at 0.1 U/ml thrombin, 20 μmol/L ADP and 0.5 μmol/L U46619 on the slide coated with 30 μg/ml fibrinogen.
15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid/pharmacology* ; Adenosine Diphosphate ; Animals ; Blood Platelets/physiology* ; Fibrinogen ; Humans ; Mice ; Mice, Inbred C57BL ; Platelet Adhesiveness/physiology* ; Thrombin/pharmacology*