ALKBH5 demethylation modification of SE-lncRNA ZMIZ1-AS1 promotes FGFR1-mediated proliferation and invasive metastasis in osteosarcoma

Osteosarcoma is the most prevalent primary malignant bone tumor in children and adolescents. However, its underlying pathogenesis and mechanisms driving metastasis remain poorly understood. Here, we identified a novel super-enhancer-associated long noncoding RNA (SE-lncRNA), Zinc Finger MIZ-Type Containing 1 Antisense RNA 1 (ZMIZ1-AS1), which is highly expressed in osteosarcoma and promoted tumor cell proliferation, migration, and invasion. Mechanistically, the m⁶A demethylase ALKBH5 post-transcriptionally stabilized ZMIZ1-AS1 through m⁶A demethylation. Furthermore, ZMIZ1-AS1 directly bound to the RNA-binding protein Polypyrimidine Tract Binding Protein 1 (PTBP1), facilitating the translocation of PTBP1 from the nucleus to the cytoplasm. The relocalized PTBP1 then bound to and stabilized fibroblast growth factor receptor 1 (FGFR1) mRNA. In nude mouse models, ZMIZ1-AS1 overexpression promoted tumor growth and lung metastasis. Notably, combined inhibition of ALKBH5 (using ALKBH5-IN-5) and FGFR1 (using BGJ398/infigratinib) synergistically suppressed ZMIZ1-AS1-driven oncogenesis in vivo. Our study establishes the ALKBH5/ZMIZ1-AS1/PTBP1/FGFR1 signaling axis as a key driver of osteosarcoma progression and a promising target for therapeutic intervention.