METTL3-mediated m6A modification contributes to anlotinib resistance in osteosarcoma by regulating ferroptosis via the circFAM120B/miR-330-3p/PRKDC axis.

N6-methyladenosine (m6A) modification plays a critical role in tumor progression and drug resistance. Here, we demonstrate that METTL3-mediated m6A modification contributes to anlotinib resistance in osteosarcoma by regulating ferroptosis through the circFAM120B/miR-330-3p/PRKDC axis. We show that anlotinib triggers ferroptosis in osteosarcoma cells by suppressing the VEGFR2/STAT3/GPX4 signaling cascade. DNA-PKcs (encoded by PRKDC) interacts with IGF1R and activates the IGF1R/STAT3/GPX4 pathway, thereby inhibiting ferroptosis. Mechanistically, circFAM120B functions as a molecular sponge for miR-330-3p, leading to PRKDC upregulation. METTL3 enhances circFAM120B stability via YTHDF1-dependent recognition and facilitates its expression, while also promoting YTHDF2-mediated degradation of pri-miR-330, resulting in reduced mature miR-330-3p. In vivo studies confirm that METTL3 overexpression increases anlotinib resistance, which is counteracted by circFAM120B knockdown or miR-330-3p overexpression. Notably, while ferroptosis represents a key mechanism, STAT3 may also contribute to anlotinib resistance through additional pathways including apoptosis, autophagy, and immune evasion, reflecting the multifunctional role of this central signaling hub. Our results delineate a novel mechanism wherein METTL3 governs ferroptosis and anlotinib resistance in osteosarcoma through dual m6A methylation of circFAM120B and pri-miR-330, offering potential targets for overcoming therapeutic resistance.