Correlation between troglitazone cytotoxicity and drug metabolic enzyme activities in cryopreserved human hepatocytes

Nicola J. Hewitt, Scott Lloyd, Mike Hayden, Ryan Butler, Yumiko Sakai, Ryan Springer, Andrew Fackett, Albert P. Li

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

Troglitazone (TRO) was developed for the treatment of type II diabetes. It was withdrawn from use due to idiosyncratic liver damage and failure. The mechanism of toxicity is still not determined, moreover, it is still not clear whether toxicity is due to the parent compound or its metabolite(s). The cytotoxicity of TRO was evaluated in human hepatocytes using previously cryopreserved hepatocyte suspensions from 27 human donors. Cellular adenosine triphosphate content was used as a viability endpoint. To investigate the role of xenobiotic metabolism in TRO toxicity, the correlation between the drug metabolism activities of the hepatocytes from each donor to EC50 values TRO cytotoxicity. The activities examined were cytochrome P450 (CYP) isoform activities (CYP2A6, CYP2D6, CYP2C19, CYP1A2, CYP2E1, CYP3A4 and CYP2C9) and phase 2 conjugation enzyme activities (phenol sulfotransferase (PST) and glucuronyl transferase (UGT)). Taken individually, none of the phase 1 or 2 enzyme activities correlated to the EC50. However, when three enzyme activities ((CYP3A4×UGT)/PST) were taken into account, a correlation was made (r2=0.53). Based on the correlation, we hypothesize that TRO and TRO sulfate are direct acting toxicants, whereas CYP3A4 oxidation and glucuronidation are detoxification pathways.

Original languageEnglish (US)
Pages (from-to)73-82
Number of pages10
JournalChemico-Biological Interactions
Volume142
Issue number1-2
DOIs
StatePublished - Nov 10 2002
Externally publishedYes

Keywords

  • Cytotoxicity
  • Drug metabolism
  • Hepatotoxicity
  • Human hepatocytes
  • P450
  • Troglitazone

ASJC Scopus subject areas

  • Toxicology

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