Targeting Mettl8-Tcf1 axis promotes CD8+ TPEX differentiation and antitumor immunity
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ABSTRACT: CD8+ T cell exhaustion represents a major obstacle to effective cancer immunotherapy. While stem-like progenitor exhausted T (TPEX) cells can differentiate into intermediate (Int-TEX) and terminally exhausted (TEX) subsets, the epigenetic regulation of this process is unclear. We identify the RNA methyltransferase Mettl8 as a critical regulator, with expression significantly higher in TPEX than in TEX subsets. In anti-PD-1 responding human NSCLC patients, Mettl8 and the stemness factor TCF7 were downregulated. In murine models, Mettl8 deletion restrained tumor progression by driving TPEX differentiation into effective Int-TEX cells. Mechanistically, Mettl8 stabilizes Tcf7 mRNA via m³C modification and enhances Tcf1 protein expression. Additionally, Mettl8 interacts with Tcf1 to facilitate chromatin looping at the Tox locus, maintaining TPEX stemness. Pharmacological Mettl8 inhibition promoted TPEX-to-Int-TEX differentiation and tumor control. Combining this inhibition with anti-PD-1 therapy yielded synergistic efficacy. Our findings establish Mettl8 as a pivotal regulator of TPEX fate and a promising therapeutic target for enhancing immunotherapy.
ORGANISM(S): Mus musculus
PROVIDER: GSE249068 | GEO | 2026/03/07
REPOSITORIES: GEO
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