MTHFD2 drives retinoblastoma progression via Notch signaling activation: Implications for targeted pediatric ocular cancer therapy

Abstract

Retinoblastoma (RB), the most prevalent intraocular malignancy in children, severely threatens vision and survival, yet therapeutic strategies for recurrent or refractory RB remain limited. MTHFD2 (Methylenetetrahydrofolate Dehydrogenase 2), one of the key enzymes involved in mitochondrial one-carbon metabolism, is aberrantly overexpressed in multiple cancers. Elevated MTHFD2 expression correlates with poor prognosis in various malignancies, and its depletion significantly suppresses tumor invasiveness and induces programmed cell death. However, whether MTHFD2 contributes to RB progression remains largely unexplored. Here, we reported that MTHFD2 expression was markedly upregulated in RB tissues and cell lines (Y79, Weri-RB1). In vitro functional assays demonstrated that MTHFD2 overexpression suppressed apoptosis and enhanced RB cell viability, colony formation, whereas MTHFD2 knockdown promoted apoptosis and inhibited RB cell viability, colony formation. In terms of mechanism, RNA sequencing and KEGG analysis revealed that differentially expressed genes (DEGs) were significantly enriched in pathways related to tumorigenesis. Meanwhile, we further demonstrated that MTHFD2 drove tumor progression by activating the Notch signaling pathway. Additionally, In vivo studies confirmed that MTHFD2 downregulation suppressed tumor graft growth and reduced expression of tumor proliferation marker Ki67. Our findings validate the critical oncogenic properties of MTHFD2 in RB by sustaining cell proliferation and preventing apoptosis. The tumor-promoting effects of MTHFD2 are likely mediated via the Notch signaling cascade, highlighting its potential as a therapeutic target for RB treatment.