Cancer Cell-Intrinsic Type I Interferon Signaling Promotes Antitumor Immunity in Head and Neck Squamous Cell Carcinoma.

Background: The cyclic GMP-AMP synthase (cGAS)-type I interferon (IFN-I) pathway detects cytoplasmic DNA and triggers immune responses. Cancer cells often suppress this pathway to evade immune surveillance; however, its therapeutic potential remains unclear. Methods: Mouse oral squamous cell carcinoma models, representing a prominent subtype of head and neck squamous cell carcinoma (HNSCC), were employed in this study. Flow cytometry, Western blot, ELISA, and PCR were used for analysis. Results: We found that immune-unresponsive MOC2 tumors exhibited a deficiency of antigen-presenting cells and cytotoxic T lymphocytes, along with a significant suppression of the cGAS-IFN-I pathway, compared to immune-responsive MOC1 tumors. An MOC2-conditioned medium impaired the differentiation of bone marrow-derived cells into dendritic cells (DCs), reducing the expression of DC markers as well as class I and II major histocompatibility complex (MHC) molecules. The activation of the cGAS-IFN-I pathway in MOC2 cells, either through exogenous DNA or direct IFN-I expression, enhanced class I MHC expression and antigen presentation on MOC2 cells. Furthermore, IFNB1 expression in MOC2 cells induced apoptosis and upregulated chemokines, such as CXCL9 and CXCL10, which recruit immune cells. In immunocompetent mice, IFNB1 expression suppressed MOC2 tumor growth by attracting DCs and T cells, an effect amplified by co-expressing the granulocyte-macrophage colony-stimulating factor. Conclusions: These findings highlight the potential of enhancing cancer cell-intrinsic cGAS-IFN-I signaling to improve tumor immune surveillance and control the progression of immune-cold HNSCC tumors.