vtRNA1-1 drives regorafenib resistance by sustaining cancer stemness via impaired autophagy and altered svRNA biogenesis.

While vault RNA1-1 (vtRNA1-1) has been implicated in tumor biology, its specific role in cancer stemness and regorafenib resistance remains unexplored. In this study, we identify vtRNA1-1 as a critical regulator of cancer stemness and chemoresistance in Hepatocellular carcinoma (HCC). vtRNA1-1 enhances stemness properties by modulating the nuclear accumulation of Nanog, a core transcription factor. This pro-stemness effect could be counteracted through autophagy activation using rapamycin or nutrient starvation. Importantly, we demonstrate that regorafenib treatment induces vtRNA1-1 upregulation, and that acquired resistance correlates with impaired vtRNA1-1 processing, leading to vtRNA1-1 accumulation and reduced generation of small vault RNAs (svRNAs). Genetic silencing of vtRNA1-1 effectively restored regorafenib sensitivity in resistant cells by promoting apoptosis and suppressing stemness markers. Our findings establish vtRNA1-1 as a novel oncogenic driver and reveal its potential as both a predictive biomarker for regorafenib response and a therapeutic target for overcoming drug resistance.