TREG Cells in Cancer: Beyond Classical Immunological Control.

A prerequisite for tumor evolution toward a malignant state is the establishment of cell intrinsic and extrinsic mechanisms of immune suppression (Hanahan and Weinberg, 2000, 2011; Schreiber, Old, and Smyth, 2011). Widespread recruitment of Foxp3+ regulatory T cells (TREG) is a prevailing means to dampen antitumor immunity. Advances in the characterization of TREG cell heterogeneity and physiological function of tissue resident TREG cells unfold new possibilities for nontraditional tumor-promoting functions of intratumoral TREG cells. This review will focus on the nonclassical function of TREG cells and their implicancies for cancer biology and treatment.