The Role And Mechanism Of Hgf Derived From GC-MSCs On The Growth Of Gastric Cancer Cells

Objective: The previous studies by our research group showed that gastric cancer mesenchymal stem cells(GC-MSCs)can promote the progression of gastric cancer through paracrine secretion,and compared with BM-MSCs,GC-MSCs have high secretion of hepatocyte growth factor(HGF),HGF has been found to be abnormally expressed in a variety of tumors and is associated with proliferation,metastasis and angiogenesis in tumor.Therefore,this study aimed to investigate the role of GC-MSCs-derived HGF in proliferation,migration and tumor formation of gastric cancer cell,as well as the effect on the expression of programmed cell death-ligand1(PD-L1)in tumor cells.Methods: The GC-MSCs and BM-MSCs were isolated and cultured from the tumor tissues of gastric cancer patients and healthy human bone marrow by tissue adherence method and their culture medium(GC-MSCs-CM,BM-MSCs-CM)were collected,Enzyme-linked immunosorbent assay(ELISA)was used to detect HGF levels in GC-MSCs-CM and BM-MSCs-CM.GC-MSCs-CM with HGF neutralizing antibody was applied to gastric cancer cell lines(SGC-7901 and/or MGC-803),the proliferation activity of gastric cancer cells was detected with CCK8 assay,the colony forming ability of gastric cancer cells was analyzed via colony formation assay,Transwell assay and cell wound scratch assay were used to measure the migration ability of gastric cancers,Western-blotting was used to detect the expression of proliferation and migration-related proteins in gastric cancer cells.By methods of Western-blotting and Flow cytometry,the expression of PD-L1 in gastric cancer cells or cancer tissues was detected.To verify the effect of HGF on gastric cancer in vivo,BALB/c nu/nu subcutaneous tumor model was constructed to observe tumor formation,then the expression of PD-L1 in tumor tissues was analyzed by Western-blotting.Gastric cancer cells were treated with exogenous HGF,and the effects of HGF on proliferation and PD-L1 expression of gastric cancer cells were further confirmed by CCK8,flow cytometry and Western-blotting.The expression of HGF levels in serum of gastric cancer patients and healthy people was determined by ELISA,and the relationship between HGF m RNA expression and overall survival rate of gastric cancer patients was analyzed through Kmplot database.Immunohistochemistry was utilized to observe the protein levels of HGF in tumor tissues of gastric cancer patients.Results: The content of HGF in GC-MSCs-CM was significantly higher than BM-MSCs-CM(P<0.05).GC-MSCs-CM treatment enhanced the proliferation,migration and colony formation of gastric cancer cells and the promoting effect could be inhibited by HGF blockade.GC-MSCs-CM could also promote the expression of PD-L1 in gastric cancer cell lines,and the proportion of PD-L1 positive cells decreased after HGF inhibition.GC-MSCs-CM promoted tumor growth in mice and enhanced the expression of PD-L1 of tumor tissues in vivo.The above promotion was significantly inhibited by using HGF neutralizing antibody.Exogenous HGF promoted the proliferation of gastric cancer cells and up-regulated the expression of PD-L1 in gastric cancer cells.The serum HGF levels in gastric cancer patients before therapy were significantly higher than those in healthy people(P<0.05)and the overall survival rate of patients with high expression level of HGF m RNA is lower.The positive rate of HGF in tumor tissues of PD-L1-positive patients is higher than PD-L1-negative patients.Conclusions: GC-MSCs-CM-derived HGF plays an important role in promoting gastric cancer cell proliferation,migration,clonal formation,PD-L1 expression and tumor growth.It may be the pivotal factor for GC-MSCs-CM to regulate the high expression of PD-L1 and promotes tumor progression in gastric cancer cells,which is expected to become a potential molecular target for prevention and treatment of gastric cancer.