Molecular mechanisms of tumor-associated macrophages in hepatocellular carcinoma development and therapy

Figure 1 Tumor-associated macrophages contribute to hepatocellular carcinoma development. Tumor-associated macrophages contribute to an immunosuppressive tumor microenvironment by activating or inducing angiogenesis, fibrosis, tumor cell metastasis, and T cell exhaustion. TAMs: Tumor-associated macrophages; VEGF: Vascular endothelial growth factor; MMPs: Matrix metalloproteinases; EGF: Endothelial growth factor; TGF: Transforming growth factor; TNF: Tumor necrosis factor; PDGF: Platelet-derived growth factor; G-CSF: Granulocyte colony-stimulating factor; GM-CSF: Granulocyte-macrophage colony-stimulating factor; IL: Interleukin; HCC: Hepatocellular carcinoma.

Figure 2 Triggering receptor expressed on myeloid cells-1 and triggering receptor expressed on myeloid cells-2 in tumor-associated macrophages modulate the infiltration and function of cluster of differentiation 8⁺ T cells and regulatory T cells, thereby impacting hepatocellular carcinoma progression. TAMs: Tumor-associated macrophages; TREM: Triggering receptor expressed on myeloid cells; CD: Cluster of differentiation; Treg: Regulatory T cell; HCC: Hepatocellular carcinoma.

Figure 3 Treatment with a dipeptidyl peptidase 4 inhibitor increases C-C motif chemokine ligand 16 expression and immune cell infiltration in the tumor microenvironment. DPP-4: Dipeptidyl peptidase 4; CCL: C-C motif chemokine ligand; STAT: Signal transduction and transcription activation; JAK: Janus kinase; IL: Interleukin; TAMs: Tumor-associated macrophages; HCC: Hepatocellular carcinoma.

Figure 4 Blocking the secreted phosphoprotein 1 signaling pathway in tumor-associated macrophages inhibits hepatocellular carcinoma growth. SPP1: Secreted phosphoprotein 1; TAMs: Tumor-associated macrophages; CD: Cluster of differentiation; IFN: Interferon; PD-1: Programmed cell death protein 1; PD-L1: Programmed cell death ligand 1; ITGF1: Integrin subunit beta 1.