NSUN2-mediated m5C modification of E2F1 promotes lung adenocarcinoma progression via the RAD54L signaling axis

Lung adenocarcinoma (LUAD) is a leading cause of cancer-related mortality, often driven by the hyperactivation of cell cycle and DNA repair pathways. While genomic alterations in these pathways are well-documented, the role of RNA epigenetics in orchestrating these oncogenic signals remains poorly understood. Here, we identify a hierarchical signaling axis driven by the RNA methyltransferase NSUN2 that fuels LUAD progression. We demonstrate that NSUN2 is frequently amplified and overexpressed in LUAD, where it correlates with advanced disease stage and poor patient survival. Mechanistically, NSUN2 catalyzes 5-methylcytosine (m5C) modification of the E2F1 3′-untranslated region (3′-UTR). This modification, recognized by the reader protein YBX1, enhances the translational efficiency of E2F1 transcripts. The resulting accumulation of E2F1 transcriptionally activates the DNA translocase RAD54L, which we redefine as a proactive oncogenic effector essential for cell proliferation, invasion, and in vivo tumorigenesis. Integrated multi-omics and rescue experiments confirm that the NSUN2-mediated translational induction of E2F1 is a prerequisite for RAD54L-driven malignancy. Our findings uncover a novel epitranscriptomic-transcriptional regulatory cascade, establishing the NSUN2-E2F1-RAD54L axis as a critical driver of LUAD and a promising target for therapeutic intervention. NSUN2-Mediated Epitranscriptomic Rewiring: Genomic amplification and overexpression of the RNA methyltransferase NSUN2 drive an aberrant m5C landscape in EGFR-mutant lung adenocarcinoma (LUAD). Translational Regulation of E2F1: NSUN2 directly catalyzes m5C modification of the E2F1 3′-UTR, which, in coordination with the reader protein YBX1, enhances E2F1 translational efficiency without altering its mRNA stability. Transcriptional Activation of RAD54L: Elevated E2F1 protein levels directly transcriptionally activate RAD54L, establishing a robust NSUN2-E2F1-RAD54L signaling axis that uncouples cell cycle progression from normal regulatory controls. Redefining RAD54L Function: RAD54L is identified as a proactive oncogenic driver in LUAD, rather than a passive DNA repair enzyme, and is indispensable for the tumorigenic and metastatic phenotypes induced by the E2F1 axis. Clinical and Prognostic Significance: Activation of the NSUN2-E2F1-RAD54L cascade correlates with advanced tumor stage and poor patient survival, nominating this epitranscriptomic-transcriptional axis as a promising therapeutic target for advanced LUAD.