HBV Hijacks Copper Cell Death Pathway to Help Liver Tumors Survive

Hepatocellular carcinoma (HCC) driven by hepatitis B virus (HBV) remains one of the deadliest and most treatment-resistant cancers worldwide. Understanding how HBV rewires tumor cell survival mechanisms is critical for developing better therapies.

This study focused on cuproptosis — a recently identified form of regulated cell death triggered by copper accumulation inside mitochondria. The researchers asked whether HBV actively suppresses this vulnerability in liver cancer cells. Using clinical tumor specimens, HBx-transgenic mice, and multi-omics datasets, they found that STEAP4, a metalloreductase protein essential for cuproptosis sensitivity, is significantly downregulated in HBV-positive HCC tumors.

Mechanistically, the HBV protein HBx reduces levels of the mitochondrial deacetylase SIRT3. Without sufficient SIRT3 activity, a specific lysine residue (K404) on STEAP4 remains acetylated, blocking STEAP4 from entering mitochondria. Cells consequently shift from TCA cycle-based oxidative respiration to glycolysis — a metabolic switch that reduces their dependence on mitochondria and shields them from copper-induced death.

Restoring STEAP4 expression or pharmacologically reactivating SIRT3 with honokiol (a natural compound) relocated STEAP4 back to mitochondria and re-sensitized cancer cells to elesclomol, a copper ionophore. The honokiol-elesclomol combination produced synergistic tumor suppression both in cell cultures and in orthotopic (surgically implanted) liver tumor mouse models.

These findings establish a clear mechanistic chain — HBx → SIRT3 suppression → STEAP4 mis-localization → glycolytic shift → cuproptosis resistance — and provide pre-clinical justification for copper-directed combination therapies in HBV-associated HCC. Caveats include reliance on animal and in vitro models, with human clinical validation still needed.