RBM15B/IGF2BP2‐m6A Mediated Upregulation of FNBP1 Promotes the Progression of Glioblastoma by Promoting Smad3‐Mediated Glycolysis

Glioblastoma (GBM) is the most common and lethal primary intracranial tumor, and glycolysis has been reported to play a critical role in its progression. Formin-binding protein 1 (FNBP1) has been implicated in GBM progression; however, the precise molecular mechanisms remain unclear. In this study, we demonstrated that FNBP1 expression was significantly higher in GBM tissues compared with adjacent tissues. Elevated FNBP1 expression was correlated with higher tumor grade and reduced 5-year survival in GBM patients. In vitro, knockdown of FNBP1 inhibited proliferation, invasion, and glycolysis, while promoting apoptosis in GBM cells. Mechanistically, RNA-binding motif protein 15B (RBM15B) increased the m6A modification level of FNBP1 mRNA, and insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) recognized this m6A mark and enhanced the stability of FNBP1 mRNA. Furthermore, FNBP1 interacted with LIM and SH3 Domain Protein 1 (LASP1), upregulating LASP1 protein expression and subsequently activating the Smad3 signaling pathway to promote glycolysis. In vivo, subcutaneous xenograft models were established using U251/U87 cells, and a lung metastasis model was generated via tail vein injection of U87 cells. FNBP1 knockdown significantly suppressed tumor growth in the subcutaneous model and reduced the number of lung nodules in the metastasis model. In conclusion, FNBP1, regulated by the RBM15B-m6A-IGF2BP2 axis, promotes GBM progression by interacting with LASP1 to activate Smad3-mediated glycolysis.