Targeting NAT10 Activates Tumor-Intrinsic Immunity and Suppresses Tumor Progression in Head and Neck Squamos Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) remain a major clinical challenge due to its high heterogeneity and limited therapeutic response, resulting in a 5-year overall survival rate of only [~]50%. Identifying molecular pathways that drive tumor progression while suppressing anti-tumor immunity is therefore critical for developing more effective therapies. NAT10 (N-acetyltransferase 10) is the only known enzyme responsible for catalyzing the RNA modification N4-acetylcytidine (ac4C) on rRNA, tRNA, and mRNA, and has been implicated in tumor progression in several cancers. In this study, we identify NAT10 as a key suppressor of tumor-intrinsic immune signaling in HNSCC. NAT10 expression was significantly elevated in tumor tissues and HNSCC cell lines and was associated with poor overall survival. Moreover, high-risk HPV, a major etiological factor in HNSCC, upregulated NAT10 protein expression through the viral oncoproteins E6 and E7. Functional inhibition of NAT10, either by genetic depletion or the small-molecule inhibitor Remodelin, activated tumor-intrinsic innate immune responses, as evidenced by increased IRF3 phosphorylation and induction of type I/II interferons and interferon-stimulated genes. Depletion of NAT10 was able to suppress tumorigenic phenotypes, including cell proliferation, migration, and colony formation in HNSCC cells. Importantly, activation of the STING signaling pathway using agonist cyclic di-GMP further amplified immune activation in NAT10-inhibited cancer cells. Together, our findings establish NAT10 as a previously unrecognized negative regulator of tumor-intrinsic immunity in HNSCC and support NAT10 targeting, particularly in combination with STING agonists, as a promising immunotherapeutic strategy.