STING-dependent cytosolic DNA sensing mediates innate immune recognition of immunogenic tumors

Spontaneous Tcell responses against tumors occur frequently and have prognostic value in patients. The mechanism of innate immune sensing of immunogenic tumors leading to adaptive Tcell responses remains undefined, although type I interferons (IFNs) are implicated in this process. We found that spontaneous CD8⁺ Tcell priming against tumors was defective in mice lacking stimulator of interferon genes complex (STING), but not other innate signaling pathways, suggesting involvement of a cytosolic DNA sensing pathway. Invitro, IFN-β production and dendritic cell activation were triggered by tumor-cell-derived DNA, via cyclic-GMP-AMP synthase (cGAS), STING, and interferon regulatory factor 3 (IRF3). In the tumor microenvironment invivo, tumor cell DNA was detected within host antigen-presenting cells, which correlated with STING pathway activation and IFN-β production. Our results demonstrate that a major mechanism for innate immune sensing of cancer occurs via the host STING pathway, with major implications for cancer immunotherapy.