The tumor-intrinsic role of the m6A reader YTHDF2 in regulating immune evasion.

Tumors evade attacks from the immune system through various mechanisms. Here, we identify a component of tumor immune evasion mediated by YTH domain–containing family protein 2 (YTHDF2), a reader protein that usually destabilizes m⁶A-modified mRNA. Loss of tumoral YTHDF2 inhibits tumor growth and prolongs survival in immunocompetent tumor models. Mechanistically, tumoral YTHDF2 deficiency promotes the recruitment of macrophages via CX3CL1 and enhances mitochondrial respiration of CD8⁺ T cells by impairing tumor glycolysis metabolism. Tumoral YTHDF2 deficiency promotes inflammatory macrophage polarization and antigen presentation in the presence of IFN-γ. In addition, IFN-γ induces autophagic degradation of tumoral YTHDF2, thereby sensitizing tumor cells to CD8⁺ T cell–mediated cytotoxicity. Last, we identified a small molecule compound that preferentially induces YTHDF2 degradation, which shows a potent antitumor effect alone but a better effect when combined with anti–PD-L1 or anti–PD-1 antibodies. Collectively, YTHDF2 appears to be a tumor-intrinsic regulator that orchestrates immune evasion, representing a promising target for enhancing cancer immunotherapy. Editor's Summary: Immune evasion mechanisms facilitate tumor growth and limit immunotherapy efficacy. Xiao et al. identified a role for YTH domain–containing family protein 2 (YTHDF2), a N⁶-methyladenosine reader protein, in regulating immune evasion in solid tumors. YTHDF2 can target CX3CL1 mRNA to limit expression, which prevents inflammatory macrophage recruitment to tumors and cytotoxic T cell responses. CD8 T cell–derived IFN-γ can mediate autophagic degradation of YTHDF2, thus sensitizing tumor cells to T cell–mediated destruction. They also identified a small molecule compound that degrades YTHDF2 in tumor cells, which exhibits antitumor effects that are further enhanced with PD-1/PD-L1 blockade. —Christiana Fogg [ABSTRACT FROM AUTHOR]