Work

NSUN2-mediated m5C hypermethylation of hsa_circ_0004516 promotes breast cancer brain metastasis by activating AKT signaling

Year: 2025

Type: article

Abstract: Breast cancer brain metastasis (BCBM) remains fatal with elusive mechanisms. Here, we unveil the first circRNA m5C methylation landscape in BCBM through MeRIP-seq (methylated RNA immunoprecipitation next-generation sequencing) identifying 7,465 BCBM-specific m5C peaks versus 5,929 in primary breast cancer (BC). A total of 48 hypermethylated and 128 hypomethylated m5C sites in BCBM (231-BR) were identified compared to BC. Bioinformatics enrichment analysis revealed hypermethylated circRNAs enriched in ERBB/VEGF signaling pathways. Among 8 validated differentially methylated circRNAs, hsa_circ_0004516 was consistently upregulated in BCBM tissues/cells and exhibited NSUN2-dependent m5C modification. Mechanistically, NSUN2-mediated m5C methylation enhanced hsa_circ_0004516 stability, evidenced by significantly shortened half-life upon NSUN2 depletion. Crucially, catalytic mutant NSUN2 (C271A/C321A) abolished this effect. Functional assays demonstrated that hsa_circ_0004516 knockdown in 231-BR cells suppressed proliferation, migration, and invasion by reducing p-AKT (Ser473) levels. The AKT activator SC79 reversed these phenotypic impairments, definitively linking hsa_circ_0004516 -driven metastasis to AKT signaling activation. Our study establishes the NSUN2-m5C- hsa_circ_0004516 -AKT axis as a novel therapeutic target and biomarker for BCBM.

Source: Non-coding RNA Research

DOI: 10.1016/j.ncrna.2025.08.009