NSUN2 promotes osteosarcoma metastasis via stabilizing UBE2S mRNA in an m5C-dependent manner

Abstract 5- methylcytosine (m5C) is a prevalent posttranscriptional RNA modification which participates in the initiation and progression of various cancers. NSUN2 is the main RNA methyltransferase import for catalyzing the m5C formation. However, its regulatory role and potential mechanism in osteosarcoma remain unclear. Here, we demonstrated that the NSUN2 expression was markedly upregulated in osteosarcoma tissues and cell lines. Clinically, increased NSUN2 expression was associated with poor prognosis. Functional studies revealed that NSUN2 significantly promoted metastasis and epithelial-mesenchymal transition (EMT) in osteosarcoma. Mechanistically, integrated analysis based on RNA sequencing and expression correlation analysis identified UBE2S as a target downstream gene of NSUN2, while NSUN2 enhanced UBE2S mRNA stabilization in an m5C-dependent manner. More importantly, UBE2S overexpression reversed the inhibition of cell invasion and EMT induced by NSUN2 knockdown. Moreover, UBE2S interacted with and ubiquitinated β-catenin, enhancing its stability and activation. Interestingly, osteosarcoma patients with dual-high expression of NSUN2 and UBE2S exhibited shorter overall survival. In summary, our study revealed that NSUN2 facilitated metastasis by enhancing the UBE2S/β-catenin axis, suggesting a potential therapeutic approach for osteosarcoma.