Epigenetic mechanism of RBM15 in affecting cisplatin resistance in laryngeal carcinoma cells by regulating ferroptosis.

Laryngeal carcinoma (LC) is a common cancer of the respiratory tract. This study aims to investigate the role of RNA-binding motif protein 15 (RBM15) in the cisplatin (DDP) resistance of LC cells. LC-DDP-resistant cells were constructed. RBM15, lysine-specific demethylase 5B (KDM5B), lncRNA Fer-1 like family member 4 (FER1L4), lncRNA KCNQ1 overlapping transcript 1 (KCNQ1OT1), glutathione peroxidase 4 (GPX4), and Acyl-CoA synthetase long-chain family (ACSL4) was examined. Cell viability, IC₅₀, and proliferation were assessed after RBM15 downregulation. The enrichment of insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3) and N6-methyladenosine (m6A) on KDM5B was analyzed. KDM5B mRNA stability was measured after actinomycin D treatment. A tumor xenograft assay was conducted to verify the role of RBM15 in LC. Results showed that RBM15 was upregulated in LC and its knockdown decreased IC₅₀, cell viability, proliferation, glutathione, and upregulated iron ion content, ROS, malondialdehyde, ACSL4, and ferroptosis. Mechanistically, RBM15 improved KDM5B stability in an IGF2BP3-dependent manner, resulting in FER1L4 downregulation and GPX4 upregulation. KDM5B increased KCNQ1OT1 and inhibited ACSL4. KDM5B/KCNQ1OT1 overexpression or FER1L4 knockdown promoted DDP resistance in LC by inhibiting ferroptosis. In conclusion, RBM15 promoted KDM5B expression, and KDM5B upregulation inhibited ferroptosis and promoted DDP resistance in LC by downregulating FER1L4 and upregulating GPX4, as well as by upregulating KCNQ1OT1 and inhibiting ACSL4. Silencing RBM15 inhibited tumor growth in vivo.