MEG3 in glioma stem cells promotes glioblastoma angiogenesis through FUBP3-mediated VGF expression

Glioblastoma (GBM) is the most prevalent primary malignant tumor of the adult central nervous system, characterized by pronounced vascularity that facilitates tumor proliferation, invasion, and progression. Although anti-angiogenic therapy has emerged as a potential treatment strategy for GBM, currently available anti-angiogenic agents, such as bevacizumab targeting VEGF, have demonstrated limited efficacy in improving patient survival. This underscores the urgent need for novel therapeutic targets and strategies. In this study, we identified that the expression of maternally expressed gene 3 (MEG3), a tumor-suppressive long non-coding RNA (lncRNA), is negatively correlated with patient prognosis. Spatial transcriptomics sequencing and RT-qPCR analyses revealed that MEG3 is highly expressed in glioma stem cells (GSCs). In vitro tube formation assays further demonstrated that MEG3 in GSCs promotes angiogenesis in human brain microvascular endothelial cells (HBMECs). Transcriptome sequencing identified VGF nerve growth factor inducible (VGF), a secreted pro-angiogenic protein, as a downstream target, and showed that MEG3 regulates the pro-angiogenic activity of GSCs by modulating VGF expression. RNA pull-down assays revealed that MEG3 binds to far upstream element-binding protein 1 (FUBP3), which also regulates VGF expression. In vivo, knockdown of MEG3 significantly extended survival in orthotopic xenograft models of GSCs. Immunohistochemical analysis of mouse tumor tissues showed a corresponding reduction in VGF levels and microvessel density following MEG3 knockdown. In conclusion, this study demonstrates that MEG3 in GSCs promotes GBM angiogenesis through a FUBP3-dependent induction of VGF expression, highlighting MEG3 as a potential therapeutic target for anti-angiogenic intervention in GBM.