KIF20A inhibits TRIM21-dependent ubiquitination of DHX9 to boost SOX2 stability, enhancing OSCC stemness and ferroptosis resistance.

Oral squamous cell carcinoma (OSCC) is an aggressive malignancy characterized by poor prognosis, largely attributable to cancer stem cell (CSC) persistence and ferroptosis resistance. However, the molecular mechanisms that coordinately regulate stemness maintenance and ferroptosis suppression in OSCC remain insufficiently characterized. In this study, KIF20A was identified as significantly overexpressed in OSCC and strongly correlated with adverse clinical outcomes. An integrative approach identified DHX9 as a candidate interactor of KIF20A. Mechanistic investigations revealed that KIF20A regulates DHX9 nucleocytoplasmic distribution and inhibits TRIM21-mediated K48-linked polyubiquitination at DHX9-K755, thereby preventing its proteasomal degradation and enhancing protein stability. Elevated DHX9 enhanced SOX2 mRNA stability, leading to upregulation of SOX2, a central regulator of both CSC maintenance and ferroptosis resistance. Functionally, KIF20A promoted CSC phenotypes, inhibited ferroptosis in vitro and in vivo, and activated the PI3K/AKT signaling pathway. Notably, treatment with ENMD-2076 (identified through Connectivity Map analysis) significantly reduced KIF20A expression, attenuated CSC characteristics, augmented cisplatin sensitivity, and exerted marked antitumor activity. These findings elucidate a novel KIF20A-DHX9-SOX2 regulatory axis that simultaneously governs CSC maintenance and ferroptosis evasion in OSCC. Targeting KIF20A, either as a monotherapy or in combination with chemotherapy, may offer a promising strategy to improve therapeutic outcomes in OSCC.