Figure 2.

Effect of BMP signaling in the tumor microenvironment. BMPs act locally to enhance self-renewal/stemness of Cancer Stem Cells (CSC) by induction of STAT3 expression. This in turn enhances the metastatic potential of tumor cells. BMPs also induce Foxp3 expression in conventional CD4 cells (CD4⁺Foxp3⁻) to become regulatory T cells (induced T_reg, iT_reg). T_reg (both iT_reg and thymic-derived natural T_reg (nT_reg)) and MDSC suppress anti-tumor response targeting granzyme/perforin producing CD8⁺ T cells, NK cells and CD4⁺ cells of Th1 lineage by cell-dependent contact and expression of suppressive cytokines or metabolites (TGF-β, IDO, arginase etc.). MDSC-Myeloid Derived Suppressor Cell, NK-Natural Killer, B-B cell, MF-Macrophage, DC-Dendritic Cell