Figure 3.
Current understanding of the role of TNF-TNFR2 signaling in the tumor microenvironment. In the tumor microenvironment (TME), tumor-associated macrophages, effector cells (CD4+ and CD8+ T effector (Teff) cells and natural killer (NK) cells), and tumor cells are the major source of TNF. In response to TNF stimulation, the number of CD4+Foxp3+TNFR2+ Treg cells are increased. These expanded Treg cells in TME are more stable in phenotype and more immunosuppressive. Moreover, TNF activates TNFR2+ myeloid-derived suppressor cells (MDSCs) and TNFR2+ mesenchymal stem cells (MSCs). Tregs, MDSCs, and MSCs likely operate collaboratively in the inhibition of the anti-tumor immune response and the promotion of tumor evasion. Further, TNFR2 signaling also promotes the survival, metastasis, and growth of the tumor.