Hepatocellular copper toxicity and its attenuation by zinc

Area of Science:

• Hepatocyte toxicology
• Cellular response to metals

Background:

• Excess copper is toxic to liver cells (HepG2).
• The protective mechanisms of zinc against copper toxicity are not fully understood.

Purpose of the Study:

• To investigate the toxic effects of excess copper on HepG2 cells.
• To elucidate the mitigating role of zinc in copper-induced toxicity.

Main Methods:

• HepG2 cells were exposed to varying concentrations of copper chloride.
• Cell viability, growth, and protein synthesis were assessed.
• The effect of zinc acetate pre-incubation on copper toxicity was evaluated.

Main Results:

• Copper concentrations above 500 microM reduced HepG2 cell survival and growth (LD50 = 750 microM).
• High copper levels (1,000 microM) inhibited protein synthesis without altering cellular ultrastructure.
• Zinc pre-treatment increased copper LD50 to 1,250 microM, enhanced protein synthesis, and induced a 10-kD protein, likely metallothionein.

Conclusions:

• Excess copper induces toxicity in HepG2 cells through mechanisms affecting survival and protein synthesis.
• Zinc mitigates copper toxicity, potentially by inducing metallothionein synthesis in hepatocytes.