The Achilles' heel of hepatocellular carcinoma: ginsenoside compound K as a novel GPX4 degrader promotes ferroptosis in hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) remains a major therapeutic challenge, highlighting the need for agents that engage non-apoptotic regulated cell death pathways. Ginsenoside compound K (CK), a bioactive metabolite derived from ginseng saponins, has demonstrated antitumor activity, however, its efficacy and underlying mechanisms in HCC are not well defined. Given the emerging role of ferroptosis in HCC, we investigated whether CK suppresses HCC by inducing this iron-dependent form of cell death. METHODS: The antitumor effects of CK were evaluated in HepG2 and Hep3B cells and in a xenograft mouse model. Ferroptotic cell death was assessed by measuring reactive oxygen species (ROS), ferrous iron (Fe²⁺), malondialdehyde (MDA), and glutathione (GSH) levels, and by rescue experiments using ferroptosis inhibitors (N-acetylcysteine, NAC; Trolox) or GPX4 overexpression. Mechanistic studies were performed using RNA sequencing, ubiquitination assays, and genetic manipulation of OTUB2 expression. RESULTS: CK inhibited HCC cell proliferation in a dose-dependent manner and robustly induced ferroptosis hallmarks, including ROS accumulation, enhanced lipid peroxidation, and GSH depletion. These cytotoxic effects were largely abrogated by ferroptosis inhibitors or GPX4 overexpression, confirming a ferroptosis-dependent mechanism. In vivo, CK significantly reduced tumor growth in xenograft models and recapitulated key ferroptosis features. Mechanistically, CK was identified as a functional inhibitor of the deubiquitinase OTUB2. Suppression of OTUB2 promoted ubiquitin-dependent degradation of GPX4, a central negative regulator of ferroptosis, thereby sensitizing HCC cells to ferroptosis. CONCLUSIONS: Our findings identify CK as a novel OTUB2 inhibitor that induces ferroptosis in HCC by destabilizing GPX4. This work delineates a previously unrecognized OTUB2/GPX4 regulatory axis in ferroptosis and supports CK as a promising candidate for further translational development for HCC therapy.