cGAS–STING and Cancer: Dichotomous Roles in Tumor Immunity and Development

cGMP–AMP synthase (cGAS)–stimulator of interferon genes (STING) sensing has emerged as a key regulator of innate immune responses to both exogenous and endogenous DNA. Recent studies reveal critical roles for this pathway in natural antitumor immunity across cancer types as well as in immune checkpoint blockade therapy. However, it is also clear that some tumors evade cGAS–STING-mediated immune responses, and immunomodulatory therapeutics are currently being explored to target this pathway. Finally, we also discuss recent observations that cGAS–STING-mediated inflammation may promote tumor initiation, growth, and metastasis in certain malignancies and how this may complicate the utility of this pathway in therapeutic development. cGMP–AMP synthase (cGAS)–stimulator of interferon genes (STING) recognizes cytosolic DNA and induces a type I interferon response in both tumor and phagocytic immune cells. cGAS–STING-induced immunity has potent antitumor effects and magnifies the effects of a variety of anticancer therapeutics. In certain tumor types, cGAS–STING promotes cancer growth and metastasis through modulation of the tumor microenvironment.