Figure 1. Tumors recycle GCs to drive Treg-mediated immunosuppression.

The murine B16 tumor cell lines express 11β-HSD1 to convert inactive GCs to their active metabolites (6). Within the tumor microenvironment of immunocompetent mice, GCs act on CD4⁺ Tregs to enhance their immunosuppressive function (6) and on CD8⁺ T cells to impede function (2), thereby promoting tumor growth. 11β-HSD1–producing B16 tumor cells in Rag2-deficient mice, which lack T and B cells, cease to expand, suggesting that GCs act locally on adaptive immune cells to promote tumor growth.