Resistance of three immortalized human hepatocyte cell lines to acetaminophen and N-acetyl-p-benzoquinoneimine toxicity.

Abstract Background/Aims: Acetaminophen toxicity in hepatocytes is attributed to generation of the toxic metabolite N -acetyl-p-benzoquinoneimine, leading to depletion of intracellular glutathione, alteration of redox potential and ultimately, cellular necrosis. We aimed to determine the effect of acetaminophen and N -acetyl-p-benzoquinoneimine on three human hepatocyte cell lines HH25, HH29 and HHY41, and for comparison, on primary rat hepatocytes, a cell type that is relatively resistant to acetaminophen-induced toxicity. Methods: We investigated the effect of incubation of rat hepatocytes and 3 hepatocyte cell lines with acetaminophen or N -acetyl-p-benzoquinoneimine on LDH release, glutathione status, mitochondrial function, CYP1A activity, albumin synthesis and DNA content. Results: We demonstrated that HH25, HH29 and HHY41 are resistant to the toxic effects of acetaminophen under conditions that induce cytotoxicity in rat primary hepatocytes, as indicated by maintenance of glutathione levels and basal LDH release. Incubation with N -acetyl-p-benzoquinoneimine caused a dose-dependent cytotoxicity in rat hepatocytes. Under comparable conditions N -acetyl-p-benzoquinoneimine had no effect on any of the hepatocyte cell lines. Nevertheless, when culturing the cells for a further 48 h, a decrease in glutathione levels, albumin synthesis, CYP1A activity, DNA content and mitochondrial function was apparent. Conclusion: HH25, HH29 and HHY41 cells are highly resistant to acetaminophen and N -acetyl-p-benzoquinoneimine-induced toxicity. They tolerate a much higher concentration of both toxins for a longer period of time compared to rat primary hepatocytes. These results are of relevance in the use of these cell lines to investigate acetaminophen hepatotoxicity, and may be of importance in the choice of cells for use in bioartificial liver support systems.