Regulation of regulatory T cells in cancer

Summary The inflammatory response to transformed cells forms the cornerstone of natural or therapeutically induced protective immunity to cancer. Regulatory T (Treg) cells are known for their critical role in suppressing inflammation, and therefore can antagonize effective anti‐cancer immune responses. As such, Treg cells can play detrimental roles in tumour progression and in the response to both conventional and immune‐based cancer therapies. Recent advances in our understanding of Treg cells reveal complex niche‐specific regulatory programmes and functions, which are likely to extrapolate to cancer. The regulation of Treg cells is reliant on upstream cues from haematopoietic and non‐immune cells, which dictates their genetic, epigenetic and downstream functional programmes. In this review we will discuss how Treg cells are themselves regulated in normal and transformed tissues, and the implications of this cross talk on tumour growth. Regulatory T (Treg) cells are critical mediators of immune function, with essential roles in controlling inflammation and tissue homeostasis. In cancer, Treg cells play a detrimental role and can antagonize the anti‐tumour immune response. This review explores the known upstream regulators of Treg cells by which the tumour environment may influence their recruitment, survival and function.