The Effect And Mechanism Of Interaction Between Platelets And BM-MSCs On The Metastasis Of Gastric Cancer Cells

Objective Platelet(Plt)and bone marrow mesenchymal stem cells(BM-MSCs)are the main cellular components of the tumor microenvironment and play an important role in the development of tumors,but the interaction between Plt and BM-MSCs and The relationship between tumors is still unclear.This study focuses on the effects of Plt on BM-MSCs growth and metastasis,and the mechanism.Methods The human BM-MSCs and healthy human peripheral blood platelets were isolated and culture in vitro.BM-MSCs were random Ly divided into the control MSCs group,Plt+MSCs group and Tumor-CM+platelets+MSCs group(T-Plt +MSCs)and collect the 24 h supernatants of the three groups,respectively.The culture supernatants were used to detect the transdifferentiation of BM-MSCs to cancer-associated fibroblasts(CAF)about ?-smooth muscle actin(?-SMA),vimentin and signalling molecules transforming growth factor-?(TGF-?)changes by Western blot;The migratory ability of BM-MSCs were analyzed by Transwell assay;cell counting method to detect the proliferation of BM-MSCs;The platelet aggregation assay was used to detect the effects of the supernatant from gastric cancer cell SGC-7901(SGC-7901-CM)and BM-MSCs(BM-MSCs-CM)on platelet aggregation.;Flow cytometry was used to detect the change of P-selectin,the activation index of SGC-7901-CM and BM-MSCs-CM for 2 h.The SGC-7901 cells and co-cultured supernatants were harvested from the MSCs group,Plt+MSCs group and T-Plt+MSCs and co-cultured with gastric cancer cells SGC-7901 for 48 hours.The tumor metastasis in vivo were observed by tail vein injection of SGC-7901 cell lines model.The results were made into pathological sections and the expression of VEGF,Ki-67,C-Myc,and Sall-4 was observed by immunohistochemistry.Formation of small tubes to test the ability of co-cultured supernatant to promote angiogenesis;The proliferation of SGC-7901 was detected by cell counting when stimulated by the co-cultured supernatants.Results The platelet aggregation ability after SGC-7901-CM and BM-MSCs-CM treatment was 58.8%±1.629% and 29.03%±1.481%,respectively,which was significantly higher than that of the Control group(6.30%±1.646%)(P<0.001,P< The expression level of P-selectin was [(31.4±1.71)%,(21.37±1.00)%]significantly higher than that of the control group [(3.17±0.04)%](P<0.001);The expression levels of ?-SMA [(0.79±0.08),(0.90±0.06)] and Vimentin protein[(0.88±0.01),(0.96±0.04)] in Plt+MSCs and T-Plt+MSCs groups were significantly higher in the MSCs group [(0.64±0.02),(0.75±0.05)](P<0.01),and the expression level of TGF-? was increased(P<0.05);The number of migrating cells in the Plt+MSCs and T-Plt+MSCs group[ The results were(340.3±27.7)and(424.3±17.6),respectively,significantly higher than those in the MSCs group(220.7±19.4)(P<0.01),and the proliferative capacity was increased(P<0.001).In vivo experiments showed that(Plt+MSCs)-CM group and(T-Plt+MSCs)-CM group had significantly more metastatic lung metastases [(4±2),(21±4)] than MSCs-CM(P< 0.01),and tumor tissue VEGF,Ki-67,C-Myc,Sall-4 positive expression increased;Compared with Control group,(Plt +MSCs)-CM group and(T-Plt + MSCs)-CM group promoted SGC-7901 proliferation and pro-angiogenic ability.Conclusion SGC-7901-CM and BM-MSCs-CM can promote Plt aggregation and activation.After Plt transfection,BM-MSCs transdifferentiated into CAF and enhanced their migration and proliferation and the ability to promote gastric cancer metastasis is enhanced in vivo.