Oxidative stress-driven m5C methylation by NSUN5 confers cisplatin resistance in lung adenocarcinoma through promoting glycolysis.

Platinum-based chemotherapy is the standard first-line treatment for advanced lung adenocarcinoma (LUAD). However, cisplatin resistance often leads to therapeutic failure, which subsequently results in cancer recurrence and metastasis. Here, we identify NSUN5 as a key driver of cisplatin resistance in response to oxidative stress. Cisplatin-induced reactive oxygen species (ROS) not only elevate NSUN5 expression through Nrf2-dependent transcriptional activation, but also enhance its methyltransferase activity by potentiating Cys359 for RNA capture. NSUN5 overexpression is clinically correlated with cisplatin resistance and poor prognosis in LUAD. Mechanistically, integrated RNA bisulfite sequencing (Bis-seq) and RNA sequencing (RNA-seq) analyses identified GLUT1 as a key target. NSUN5 catalyzes m5C methylation of GLUT1 mRNA through two functional sites, Cys359 for RNA binding and Cys308 for the release of m5C-modified RNA. YBX1 subsequently recognizes and stabilizes this m5C-modified transcript. Ultimately, NSUN5 enhances glucose uptake in a GLUT1-dependent manner, leading to increased glycolysis and thereby promoting homologous recombination (HR) repair. Functional studies confirmed that NSUN5 knockdown sensitized LUAD cells to cisplatin through increasing DNA damage, whereas its exogenous expression produced opposite effects. Crucially, silencing GLUT1 partially reversed NSUN5-mediated cisplatin resistance in vitro and in vivo. In summary, NSUN5 acts as a key translator that converts oxidative stress signals into enhanced HR repair by modulating the Warburg effect, thus highlighting its therapeutic potential for overcoming acquired chemoresistance in LUAD.