Table 1.
Key inflammatory cells in cancer with antitumor or protumoral activities
| Cell type | Protumor activities | Antitumor activities |
|---|---|---|
| Tumor-associated neutrophils (TANs) | ||
| •Promote tumor angiogenesis by inducing continuous release of VEGF from peripheral endothelial cells | •N1 TANs exert an antitumor activity, by direct or indirect cytotoxicity | |
| •Suppress antitumor immunity via production of proinflammatory | ||
| •Create immunosuppressive microenvironment via production of immunosuppressive factors | ||
| •Facilitate the remodeling of local microenvironment that favors tumor cell extravasation through NETs | ||
| Tumor-associated macrophages (TAMs) | ||
| •M2 TAMs induce tumor angiogenesis by upregulating angiogenesis-associated genes such as VEGF | •M1 TAMs facilitate the recruitment and antitumor activities of cytotoxic CD8 + T cells and NK cells | |
| •M2 TAMs facilitate the degradation of tumor extracellular matrix and the metastasis of tumor cells | ||
| •M2 TAMs activate the response of endothelial cells to growth factor signaling | ||
| •M2 TAMs upregulate TGF-β that promotes EMT | ||
| Dendritic cells (DCs) | ||
| •Induce T cell tolerance under pressure of tumor cells | •Provide initial signal for the antitumor response of CD8 + T cells | |
| •Inhibit the proliferation and functional cytokine production of activated T cells by expressing PD-L1 and PD-L2 | •Facilitate antitumor T cell response induced by immunogenic cell death | |
| Myeloid-derived suppressor cells (MDSCs) | ||
| •Suppress antitumor immunity by producing immunosuppressive cytokines | ||
| •Promote tumor angiogenesis via VEGF and matrix metallopeptidase | ||
| •Decrease the expansion and activation of tumor-specific T cells by expressing colony-stimulating factor-1 receptor | ||
| Vascular endothelial cells | ||
| •Promote selectin-mediated rolling of tumor cells due to weakened vascular endothelial junctions upon inflammation | •Form a barrier for blood components including tumor cells to infiltrate tissues under physiological conditions | |
TGF-β, transforming growth factor-β; NETs, neutrophil extracellular traps; NK, natural killer; TAM, tumor-associated macrophage; VEGF, vascular endothelial growth factor