Summary STING (stimulator of interferon genes) has been shown to be critical for controlling anti-viral responses, as well as anti-tumor adaptive immunity but little is known regarding its regulation in human tumors. Here, we report that STING-signaling is recurrently suppressed in a wide variety of cancers, including colorectal carcinoma. Loss of STING signaling impeded DNA damage responses accountable for generating key cytokines that facilitate tissue repair and anti-tumor-T cell priming, such as type I interferon (IFN). Correspondingly, defective STING function was also highly predictive of effectual DNA virus-mediated oncolytic activity. Thus, impaired STING responses may enable damaged cells to evade host immunosurveillance processes, although provides a critical prognostic measurement that could help predict the outcome to effective oncoviral therapy.

Inflammatory autoimmune diseases such as systemic lupus erythematosus (SLE) and polyarthritis are characterized by chronic cytokine overproduction, suggesting that the stimulation of host innate immune responses, speculatively by persistent infection or self nucleic acids, plays a role in the manifestation of these disorders. Mice lacking DNase II die during embryonic development through comparable inflammatory disease because phagocytosed DNA from apoptotic cells cannot be adequately digested and intracellular host DNA sensor pathways are engaged, resulting in the production of a variety of cytokines including type I IFN. The cellular sensor pathway(s) responsible for triggering DNA-mediated inflammation aggravated autoimmune disease remains to be determined. However, we report here that Stimulator of IFN Genes (STING) is responsible for inflammation-related embryonic death in DNase II defective mice initiated by self DNA. DNase II-dependent embryonic lethality was rescued by loss of STING function, and polyarthritis completely prevented because cytosolic DNA failed to robustly trigger cytokine production through STING-controlled signaling pathways. Our data provides significant molecular insight into the causes of DNA-mediated inflammatory disorders and affords a target that could plausibly be therapeutically controlled to help prevent such diseases.

Chronic stimulation of innate immune pathways by microbial agents or damaged tissue is known to promote inflammation-driven tumorigenesis by mechanisms that are not well understood. Here we demonstrate that mutagenic 7,12-dimethylbenz(a)anthracene (DMBA), cisplatin and etoposide induce nuclear DNA leakage into the cytosol that intrinsically activates stimulator of interferon genes (STING)-dependent cytokine production. Inflammatory cytokine levels are subsequently augmented in a STING-dependent extrinsic manner by infiltrating phagocytes purging dying cells. Consequently, STING−/− mice, or wild-type mice adoptively transferred with STING−/− bone marrow, are almost completely resistant to DMBA-induced skin carcinogenesis compared with their wild-type counterparts. Our data establish a role for STING in the control of cancer, shed significant insight into the causes of inflammation-driven carcinogenesis and may provide a basis for therapeutic strategies to help prevent malignant disease.