Influence Of Inflammatory Microenvironment Mediated By M2-tumor Associated Macrophages On Liver Cancer Stem Cells

Background and ObjectiveM2-type tumor associated macrophage(M2-TAMs)is the most abundant immune cells infiltrating tumor microenvironment(TME),which promotes hepatocellular carcinoma(HCC)initiation and progression through kinds of mechanisms.Reports show that epithelial-mesenchymal transition(EMT)is closely related to sternness of tumor cells,leading to tumor development,drug resistance and recurrence.However,in HCC,it remains unknown that M2-TAMs promote sternness of HCC cells by EMT through certain mechanisms.In this study,we explore the mechanisms in which HCC is triggered by M2-TAMs.Clarifying the fact that TNF-a derived from M2-TAMs promotes EMT and cancer sternness in HCC,providing new thoughts in targeting HCC.Methods and ResultsIn this study,we have co-cultured HCC cell line SMMC-7721 cells with M2-TAMs induced from THP-1 cell line.Next,we used nude mice subcutaneous tumor to observe whether the growth of tumor was affected by M2-TAMs.EMT related markers(E-cadherin,N-cadherin,Vimentin cancer sternness related markers(CD 133,Oct-4,Sox-2)and Wnt signaling pathway ?-catenin are detected to verify the changes of EMT and cancer sternness both in cells and subcutaneous tumor.Our results showed that the morphology of SMMC-7721 cells changed significantly after co-cultured,tending to the morphology of mesenchymal cell.Markers detection showed SMMC-7721 cells undergone EMT and enhanced sternness and drug resistance ability.In animal models,larger tumor size following subcutaneous injection of SMMC-7721 suspended in M2-TAMs supernatants(experimental group)compared with SMMC-7721 alone(control group),and tumor growth was faster.At the same time,we detected the expression of TNF-a in the serum of all nude mice.We found that TNF-a is highly expressed in experimental group and which in nude mice serum positively correlated with subcutaneous tumor size.We further investigated that the Wnt/p-catenm signaling pathway is a downstream pathway of TNF-a,and Wnt pathway inhibitor ICG-001 could partially reverse EMT and weaken cancer sternness in SMMC-7721 cells.Overall,our study demonstrates that TNF-a from M2-TAM promotes EMT and cancer stem cells in HCC via the Wnt pathway.ConclusionsTNF-? derived from M2-TAMs in TME correlates with EMT and cancer sternness of HCC,promoting growth of HCC in vivo.In-depth study of the mechanism found that the Wnt/?-catenin pathway is a downstream pathway of TNF-a,blocking this pathway can partially reverse EMT and cancer stem cells...