Background

Ferroptosis is an emerging iron-dependent programmed cell death mode characterized by lipid peroxidation and iron accumulation, closely associated with Hepatocellular Carcinoma (HCC) progression. Although the impact of Polyphyllin I (PPI), a prominent bioactive constituent derived from Paris polyphylla, on diverse malignancies has been established, the specific role and potential mechanistic pathways through which PPI modulates ferroptosis in HCC remain elusive.

Purpose

This study aimed to elucidate the anti-cancer properties and potential mechanisms of PPI in inducing ferroptosis and triggering mitochondrial injury in HCC.

Methods

Cell viability was assessed using CCK-8 assays. EdU proliferation and colony formation assays were employed to evaluate cell proliferation. A wound-healing assay was performed to assess cell migration. Transwell assay was utilized to evaluate cell invasion. Ferroptosis was evaluated through the utilization of a FerroOrange fluorescent probe, malondialdehyde (MDA) and reduced glutathione (GSH) assay kits, DCFH-DA fluorescent probe, western blotting, and transmission electron microscopy (TEM) analysis. Molecular docking, immunofluorescence, and western blotting were employed to predict and validate the binding and interaction of PPI with Nrf2, HO-1, xCT, and GPX4. Mitochondrial structure and membrane potential changes were evaluated using JC-1 and Mito Tracker Green fluorescent probes. A nude mice xenograft model was constructed to determine the inhibitory effects and the levels of ferroptosis of PPI on HCC through hematoxylin and eosin (H&E), Prussian blue reaction, immunofluorescence staining, immunohistochemistry, and western blotting analysis, in vivo.

Results

PPI exhibited dose-dependent inhibitory effects on the proliferation, invasion, and metastasis of HCC cells mediated by increasing reactive oxygen species (ROS) and MDA levels, promoting Fe²⁺ accumulation, depleting GSH, and suppressing the expression of xCT and GPX4, thereby inducing ferroptosis in HCC. The induction of ferroptosis by PPI was associated with the binding of PPI to Nrf2, HO-1, and GPX4 proteins, modulating the Nrf2/HO-1/GPX4 antioxidant axis. PPI also induced mitochondrial structural damage and decreased mitochondrial membrane potential (MMP). Inhibition of ferroptosis by ferrostatin-1 (Fer-1) mitigated the mitochondrial disruption induced by PPI. In vivo, PPI inhibited Nrf2/HO-1/GPX4 axis-induced ferroptosis, impeding HCC growth similar to the effects of sorafenib.

Conclusion

These results demonstrated that PPI intervention can suppress the proliferation, invasion, and metastasis of HCC cells by enhancing mitochondrial disruption and inducing ferroptosis via the Nrf2/HO-1/GPX4 axis. Consequently, our research advances the frontiers of pharmacodynamics and deepens our comprehension of the intricate mechanisms underpinning PPI. Furthermore, it has yielded an innovative treatment stratagem rooted in the tenets of Traditional Chinese Medicine (TCM), thereby furnishing a novel therapeutic avenue for addressing HCC.