The two faces of regulatory T cells in cancer.

Regulatory T cells (Tregs) that expand in human colon cancer express retinoid-related orphan receptor γt (RORγt) and exert potent T-cell suppressive functions while mediating pro-inflammatory effects. Similar Tregs expand and drive a vicious cycle of inflammation in murine polyposis. Targeting RORγt in Tregs interrupts such a cycle and protects mice against polyposis, suggesting that a similar intervention may provide therapeutic benefits to colon cancer patients.