NSUN2 promotes leukemogenesis by ferritin heavy chain 1-mediated anti-ferroptosis and enhancing global protein synthesis in an m(5)C-dependent manner in B-acute lymphoblastic leukemia.

BACKGROUND: NOP2/Sun RNA methyltransferase family member 2 (NSUN2) catalyzes 5-methylcytosine (m(5)C) modifications in tRNA, rRNA, and mRNA, playing critical roles in various malignancies. However, its expression and functional relevance in B-acute lymphoblastic leukemia (B-ALL) remain largely undefined. METHODS: Lineage-negative progenitor cells from Nsun2 knockout (Δ/Δ) and wild-type (fl/fl) mice were used to generate BCR-ABL (P190)-driven murine B-ALL model. Furthermore, RNA sequencing (RNA-seq) was performed to identify NSUN2 targets. Cell proliferation, apoptosis, and colony formation, and global protein synthesis were measured in B-ALL cells with NSUN2 deficiency. RESULTS: Here, we found that NSUN2 expression was significantly higher in bone marrow (BM) cells from B-ALL patients than normal controls (NCs). Knockdown of NSUN2 reduced m(5)C amounts and induced ferroptosis and apoptosis in B-ALL cells. Moreover, Nsun2 knockout significantly suppressed the leukemic burden and extended the OS in the murine B-ALL model in vivo. RNA-seq and subsequent studies identified ferritin heavy chain 1 (FTH1) as a downstream target of NSUN2. NSUN2 depletion sensitized B-ALL cells to ferroptosis induction via inhibiting FTH1 expression. In addition, overexpression of FTH1 rescued the ferroptosis and apoptosis induced by NSUN2 knockdown. Mechanistically, NSUN2 knockdown reduced m(5)C modifications on 3'UTR of FTH1 mRNA, impairing its stability and reducing FTH1 expression. Overexpression of wild-type (WT) NSUN2, but not its mutants, blocked NSUN2 knockdown-induced cytotoxic effects, indicating that NSUN2 enhances leukemogenesis in an m(5)C-dependent manner. In addition, NSUN2 deficiency inhibited global protein synthesis in both human and murine B-ALL cells. In contrast, Nsun2 depletion had a minimal impact on ferroptosis and protein synthesis in murine pre-B (B220(+)) cells, suggesting selective leukemic dependency. CONCLUSIONS: Our results demonstrate that NSUN2 facilitates leukemogenesis by increasing FTH1 expression and enhancing global protein synthesis in an m(5)C-dependent manner. Targeting NSUN2 might provide a promising therapeutic strategy for B-ALL.