Functional analysis and drug response to zinc and D-penicillamine in stable ATP7B mutant hepatic cell lines

AIM: To study the effect of anti-copper treatment for survival of hepatic cells expressing different ATP7 B mutations in cell culture. METHODS: The most common Wilson disease(WD) mutations p.H1069 Q, p.R778 L and p.C271*, found in the ATP7 B gene encoding a liver copper transporter, were studied. The mutations represent major genotypes of the United States and Europe, China, and India, respectively. A human hepatoma cell line previously established to carry a knockout of ATP7 B was used to stably express WD mutants. m RNA and protein expression of mutant ATP7 B, survival of cells, apoptosis, and protein trafficking were determined.RESULTS: Low temperature increased ATP7 B protein expression in several mutants. Intracellular ATP7 B localization was significantly impaired in the mutants. Mutants were classified as high, moderate, and no survival based on their viability on exposure to toxic copper. Survival of mutant p.H1069 Q and to a lesser extent p.C271* improved by D-penicillamine(DPA) treatment, while mutant p.R778 L showed a pronounced response to zinc(Zn) treatment. Overall, DPA treatment resulted in higher cell survival as compared to Zn treatment; however, only combined Zn + DPA treatment fully restored cell viability. CONCLUSION: The data indicate that the basic impact of a genotype might be characterized by analysis of mutant hepatic cell lines.