Emodin triggers cuproptosis to suppress hepatocellular carcinoma via SLC7A11/FDX1 axis.

[BACKGROUND] Hepatocellular carcinoma (HCC) is a lethal malignancy with limited therapeutic options, necessitating novel treatment strategies. This study investigates the potential of emodin, a natural anthraquinone, to suppress HCC by inducing cuproptosis, a newly identified form of regulated cell death.

[METHOD] The anti-tumor effects of emodin were evaluated both using HCCLM3 cells and using nude mouse xenograft models. A series of assays were employed to assess cell proliferation, apoptosis, intracellular copper ion levels, and glutathione (GSH) levels. The expression of key proteins (FDX1, SLC7A11, GPX4) was examined by Western blot and immunohistochemistry. Furthermore, bioinformatics analysis was conducted to predict the interaction between emodin and cuproptosis-related proteins. Crucially, FDX1-knockdown (si-FDX1) and pharmacological inhibition experiments using the copper chelator tetrathiomolybdate (TTM) were performed to establish causality and pathway specificity.

[RESULT] Emodin treatment dose-dependently inhibited HCC cell proliferation, promoted apoptosis, elevated intracellular copper levels, and reduced GSH. Mechanistically, emodin upregulated the expression of FDX1 while downregulating SLC7A11 and GPX4. Molecular docking analysis supported the binding capability of emodin to these core proteins involved in cuproptosis. Most importantly, FDX1 knockdown abolished emodin-induced copper accumulation and rescued cell death. Furthermore, the cytotoxicity was specifically reversed by the cuproptosis inhibitor TTM, but not by ferroptosis or apoptosis inhibitors, confirming the specificity of the death pathway.

[CONCLUSION] Our findings demonstrate that emodin triggers cuproptosis in HCC via the SLC7A11/FDX1 axis. This reveals a novel mechanism underlying emodin's anti-tumor activity and highlights its promise as a therapeutic agent for HCC, particularly in SLC7A11-overexpressing subtypes, with potential to enhance combination therapies and overcome drug resistance.