Fig. 1
From: Targeting tumor-associated macrophages for cancer treatment
M2-like TAMs enhance cancer progression. M2-like TAMs accelerate cancer progression through four ways. (1) M2-like TAMs promote cell proliferation and tumorigenesis via secreting growth factors including CCL2, IL-6 and IL-10 to advance the activation of proliferation pathways in cancer cells. In addition, M2-like TAMs act on CAFs to lead to ECM degradation. (2) M2-like TAMs secrete EGF/VEGF to activate EMT-related pathways, and produce MMPs and CCL20 to enhance tumor invasion and migration. (3) M2-like TAMs strengthen tumor angiogenesis by secreting exosomes, MMPs and VEGF. (4) M2-like TAMs advance immunosuppression by downregulating CXCL9 /CXCL10 and secreting IL-10 and TGF-β to inhibit recruitment of CD8 T cells, while IL-10 and TGF-β improve cell proliferation of Tregs that contribute to tumor immune escape. TAMs tumor-associated macrophages, TME tumor microenvironment, CAFs tumor-associated fibroblasts, CCL2 chemokine (C-C motif) ligand 2, MMPs matrix metalloproteinases, VEGF vascular endothelial growth factor, PD-1 programmed cell death 1(PD-1), PD-L1 PD ligand 1, Tregs regulatory T cells