Identification of pro-apoptotic genes as toxicity-predictive biomarkers using hES-derived hepatocyte-like cells

Abstract

Toxicogenomics is a new emerging field which combines toxicology with genomics to understand the toxicity and efficacy of drugs in drug development. The altered gene expression patterns induced by reference toxic compounds show the list of potential toxic molecules involved in cytotoxic signal pathway causing adverse drug effects. One of the most important issues for the application of potential toxicity-predictive biomarkers discovered by toxicogenomics is to establish human biology-based toxicity test because there are some limitations to extrapolate between animal models and human, such as differences of metabolic enzymes among species. Drug-induced liver injury (DILI) is a phenomenon of adverse drug activity. It is important to identify potential toxicity-predictive biomarkers associated hepatotoxicity.

In this study, microarray data from hES-derived hepatocyte-like cells treated with known hepatotoxic drugs, namely APAP, diclofenac, and thioacetamide, was analyzed by Ingenuity Pathway Analysis (IPA). Based on molecular networks predicted by IPA, we choose to up-regulated pro-apoptotic proteins; ATF3 and GADD34 as target genes with cytotoxic properties. We confirmed that mRNA and protein levels of ATF3 and GADD34 were increased after treating with the three hepatotoxic drugs, corresponding with IPA results. We further identified the ER stress pathway consisting of ATF3 and GADD34, ultimately culminating apoptosis. Collectively, these data suggested that hepatotoxic drugs induce pro-apoptotic proteins which are involved in ER stress-mediated apoptosis. Such toxic proteins could be a useful toxicity-predictive biomarker for evaluating a potential hepatotoxicant triggering ER stress.