Deubiquitinase USP32 stabilizes DDX17 to promote tumor progression and lenvatinib resistance in hepatocellular carcinoma via the miR-3163/MAPK pathway.

Lenvatinib, a first-line therapy for hepatocellular carcinoma (HCC), is frequently compromised by the development of acquired resistance. Although aberrant protein ubiquitination contributes to drug resistance, the underlying mechanisms remain incompletely understood. In this study, we identify ubiquitin-specific protease 32 (USP32) as a clinically significant oncogene that is overexpressed in HCC and closely associated with aggressive tumor progression and lenvatinib resistance. USP32 knockdown markedly inhibits tumor growth, metastasis, and restores lenvatinib sensitivity both in vitro and in vivo, whereas USP32 overexpression aggravates malignant behaviors. Mechanistically, USP32 directly interacts with and deubiquitinates DEAD-box helicase 17 (DDX17) by cleaving K48-linked polyubiquitin chains, thereby stabilizing DDX17. Furthermore, DDX17 transcriptionally represses the tumor-suppressive microRNA miR-3163, leading to hyperactivation of the MAPK signaling pathway involved in lenvatinib resistance. Notably, combined treatment with the MAPK inhibitor selumetinib and lenvatinib synergistically overcomes drug resistance in lenvatinib-resistant xenograft models. Collectively, our findings identify USP32 as an important regulator of HCC malignancy and lenvatinib resistance via the DDX17/miR-3163/MAPK axis, highlighting its potential as a therapeutic target in refractory HCC.