Xia Guo

YTHDF3 suppresses interferon-stimulated gene (ISG)-dependent antitumor immunity and promotes HPV carcinogenesis in cervical cancer

Abstract Interferon-stimulated genes (ISGs) serve as evolutionarily conserved mediators of antiviral defense and tumor surveillance. Emerging evidence underscores the non-oncogenic addiction of high-risk human papillomavirus (hrHPV) E6/E7 oncoproteins in maintaining malignant phenotypes and cervical carcinogenesis. Here, we leveraged CRISPR/Cas9-engineered YTHDF3-knockout (YTHDF3 −/− ) SiHa cells and Ythdf3 −/ − mice to dissect the molecular arbiters governing m 6 A-dependent RNA regulation in HPV-driven carcinogenesis. To further elucidate the role of YTHDF3 in HPV-induced immunosuppressive tumor microenvironment (ITME) formation, we demonstrated that YTHDF3, an m 6 A RNA reader, suppresses type I ISGs responses. Notably, elevated m 6 A modification and YTHDF3 protein levels were observed in HPV + CCa tissues. Mechanistically, YTHDF3 bound to the m 6 A methylation site of STAT3 mRNA, enhancing its stability and transcription efficiency. This YTHDF3-STAT3 axis repressed ISG (e.g., IRF7) transcription and IFN-α production, thereby compromising antiviral immunity and facilitating HPV E6/E7 persistence. Correspondingly, Ythdf3 − mice bearing TC-1 xenografts exhibited a significant reduction in immunosuppressive immune cell infiltration, including Tregs, M2 macrophages, and MDSCs, accompanied by enhanced CD8 + T cell activation. Collectively, our findings unveiled that YTHDF3-mediated upregulation of STAT3 suppresses the type I ISG expression, thus promoting HPV carcinogenesis and establishing an ITME. Taken together, our results suggest that targeting the YTHDF3/STAT3/IRF7 axis could be a promising therapeutic strategy against HPV-associated malignancies.

NAT10/ac4C/FOXP1 Promotes Malignant Progression and Facilitates Immunosuppression by Reprogramming Glycolytic Metabolism in Cervical Cancer

AbstractImmunotherapy has recently emerged as the predominant therapeutic approach for cervical cancer (CCa), driven by the groundbreaking clinical achievements of immune checkpoint inhibitors (ICIs), such as anti‐PD‐1/PD‐L1 antibodies. N4‐acetylcytidine (ac4C) modification, catalyzed by NAT10, is an important posttranscriptional modification of mRNA in cancers. However, its impact on immunological dysregulation and the tumor immunotherapy response in CCa remains enigmatic. Here, a significant increase in NAT10 expression in CCa tissues is initially observed that is clinically associated with poor prognosis. Subsequently, it is found that HOXC8 activated NAT10 by binding to its promoter, thereby stimulating ac4C modification of FOXP1 mRNA and enhancing its translation efficiency, eventually leading to induction of GLUT4 and KHK expression. Moreover, NAT10/ac4C/FOXP1 axis activity resulted in increased glycolysis and a continuous increase in lactic acid secretion by CCa cells. The lactic acid‐enriched tumor microenvironment (TME) further contributed to amplifying the immunosuppressive properties of tumor‐infiltrating regulatory T cells (Tregs). Impressively, NAT10 knockdown enhanced the efficacy of PD‐L1 blockade‐mediated tumor regression in vivo. Taken together, the findings revealed the oncogenic role of NAT10 in initiating crosstalk between cancer cell glycolysis and immunosuppression, which can be a target for synergistic PD‐1/PD‐L1 blockade immunotherapy in CCa.

METTL3-mediated HSPA9 m6A modification promotes malignant transformation and inhibits cellular senescence by regulating exosomal mortalin protein in cervical cancer

The role of RNA methyltransferase 3 (METTL3) in tumor progression when tethered to aberrantly expressed oncogenes remains unknown. In especial, the correlation between cervical cancer (CCa)-derived exosomes and m6A methylation in malignant traits of cervical epithelium is currently elusive. Mortalin expression was found to be up-regulated in plasma exosomes isolated from CCa patients. Furthermore, mortalin gained increased mRNA stability and enhanced translation efficiency via the m6A methylation in the HSPA9 mRNA 3'UTR, which was catalysed by METTL3 in CCa cells. Exosomal mortalin overexpression significantly promoted the proliferation, migration and invasion of CCa both in vitro and in vivo. Additionally, exosome-encapsulated mortalin suppressed cellular senescence and facilitated malignant transformation by blocking nuclear transport of p53, thereby preventing the p53-Gadd45A interaction and resulting in inactivation of p53. Our studies demonstrated the significant role of METTL3 mediated exosomal mortalin in malignant transformation and cellular senescence suppression of CCa. Exosomal mortalin could clinically serve as a potential early-diagnosis biomarker and therapeutic target for CCa given its abundance and propensity to be found.