Investigating The Role Of Platelet αⅡbβ3 Pathway In The Progression Of Multiple Myeloma

Background and objective:Multiple myeloma（MM）,the second most common hematologic malignancy,is currently incurable.Platelet（PLT）has been shown to influence the progression of malignancies in many ways by interacting with cancer cells.In the bone marrow,PLTs are widespread and can be in close contact with MM cells.αⅡbβ3 signal pathway is the key pathway in the aggregation and release of PLT,but whether it plays an important role in the progression of MM remains unclear.The thesis aimed to investigate the role of PLTαⅡbβ3 signal pathway in the progression of multiple myeloma.Methods:The morphological structure,activity,and related cytokines of PLT in MM patients and healthy people were analyzed using microscopic examination,flow cytometry,and enzyme-linked immunosorbent assay,respectively.In addition,flow cytometry,confocal microscopy,and a series of cell experiments were used to observe the changes of PLT and co-cultured MM cells after the intervention of PLTαⅡbβ3 signal pathway with activator and inhibitors.Results:Compared with healthy people,the PLTs of MM patients were more irregular morphology,with more vacuoles,lipid droplets,mild swelling of some mitochondria,and higher activation ratios.Tests of PLT-related cytokines in serum found that PF4 was down-regulated in the MM group,while growth factors,P-selectin,IL-6,and TGF-β1 were up-regulated.After Thrombin activation,the total intracellular Ca²⁺level of PLT was enhanced and mitochondrial membrane potential decreased.The pretreatment ofαⅡbβ3 inhibitor Eptifibatide and Src inhibitor DGY-06-116 failed to effectively alleviate the effects of Thrombin on Ca²⁺levels.However,with the increase of concentration of DGY-06-116,Thrombin induced mitochondrial membrane potential decline was gradually mitigated.PLT stimulated by 1.0 U/ml Thrombin significantly raised PAC-1（activatedαⅡbβ3）.Eptifibatide pretreatment effectively suppressed the PAC-1 expression induced by Thrombin,whereas DGY 06-116 did not.Further tests showed that both 5μM DGY-06-116 and 25μM Eptifibatide effectively inhibited PLT aggregation.Co-culture tests showed that PLTs with appropriate concentration promoted MM cell proliferation,which was further enhanced by activating platelets with Thrombin.Besides,inhibition of PLTαⅡbβ3 signal pathway by 25μM Eptifibatide or 1.0μM DGY-06-116 significantly decreased the proliferative activity of MM cells.Moreover,PLT can also affect the expression of STAT3,IL-34 and TGF-β1.However,no significant effect of PLT on the invasiveness of MM cells and the phosphorylation of NF-κB,Akt and ERK1/2 was found.Conclusion:The PLTαⅡbβ3 signal pathway,which can affect the proliferation of MM cells and the expression of STAT3 and some cytokines,may be a potential therapeutic target for MM.The novel Src inhibitor DGY-06-116 may be one of the potential drugs to affect MM progression by disrupting the PLTαⅡbβ3 signal pathway.