Differences in hepatotoxicity and gene expression profiles by anti-diabetic PPAR γ agonists on rat primary hepatocytes and human HepG2 cells

Abstract

Agonists of peroxisome proliferator-activated receptor gamma (PPARgamma) are a new class of oral drugs designed to treat insulin-resistant diabetes (i.e., type 2 diabetes). However, troglitazone, the first compound in the class approved by the US Food and Drug Administration (FDA) in 1997 was found to be hepatotoxic and was withdrawn from the market after reports of severe liver failure. The mechanism of PPAR gamma agonist-induced hepatotoxicity remains unknown. In this study, we examined the hepatotoxic effects of five PPAR gamma agonists (ciglitazone, pioglitazone, rosiglitazone, troglitazone, and JTT-501) on rat primary hepatocytes and human HepG2 cells. We also compared the gene expression profiles of rat primary hepatocytes after exposure to PPAR gamma agonists by using the Rat Genome Survey Microarray system from Applied Biosystems in order to understand the mechanisms of hepatotoxicities induced by PPARgamma agonists. Consistent with the hepatotoxicity data, our results demonstrate that the gene expression profiles affected by troglitazone and ciglitazone can be clearly distinguished from those by pioglitazone and rosiglitazone. Genes that are differentially expressed between the more toxic troglitazone/ciglitazone group and the less toxic rosiglitazone/pioglitazone group are involved in necrotic, apoptotic, and cell proliferative pathways. The five compounds were also clustered based on a set of molecular descriptors. The clustering based on chemical structural information is in good agreement with the clustering of compounds based on cytotoxicity or gene expression data, indicating a strong relationship between chemical structure and biological endpoints. Our work suggests that microarray analysis together with toxicological observations can be used to rank drugs for hepatotoxicity and to evaluate the safety of new compounds.

Trovafloxacin-Induced Gene Expression Changes in Liver-Derived in Vitro Systems: Comparison of Primary Human Hepatocytes to HepG2 Cells

“…We compared the gene expression changes in HepG2 cells after TVX treatment with those induced by troglitazone in rat hepatocytes, another drug associated with idiosyncratic liver toxicity, as determined by Guo et al (2006). Of the 33 cell death-related genes that Both the genes and experiments were clustered with the agglomerative method using the average link heuristic criteria and using cosine correlation for the similarity measure; 4646 individual probe sets are displayed.…”

“…Another hepatic IDR-causing drug, troglitazone, has similarly been shown to induce a unique set of gene expression changes in rat hepatocytes and to induce a greater number of gene expression changes than a set of negative control compounds (Guo et al, 2006). In an attempt to identify potential commonalities in the effects of IDR-inducing drugs on liver cells, it may prove worthwhile to inspect the similarities between distinct IDR-causing drugs, and therefore, potentially identify and characterize concordances in mechanism(s) (if any).…”

“…In an attempt to identify potential commonalities in the effects of IDR-inducing drugs on liver cells, it may prove worthwhile to inspect the similarities between distinct IDR-causing drugs, and therefore, potentially identify and characterize concordances in mechanism(s) (if any). Indeed, many of the transcripts identified as being regulated uniquely by troglitazone versus its negative controls (Guo et al, 2006) were also regulated uniquely by TVX in HepG2 cells. Hence, these results point to the utility of HepG2 cells as one potential model in the study of hepatic IDRs, despite the basal transcriptomic variation.…”

“…Our laboratory has previously demonstrated that microarray analysis can distinguish trovafloxacin from other quinolones not associated with hepatic toxicity in PHH (Liguori et al, 2005). Since then, other examples of unique gene expression patterns in PHH or other culture systems from IDRcausing drugs relative to pharmacologically related compounds have been reported (Kier et al, 2004;Guo et al, 2006). In these examples, several endpoints including gene expression patterns induced by the IDR-causing drug, troglitazone, could be distinguished from those for other thiazolidinediones in several cell types, including PHH, rat hepatocytes, or HepG2 cells.…”

The peroxisome proliferator-activated receptor γ ligands, pioglitazone and 15-deoxy-Δ12,14-prostaglandin J2, have antineoplastic effects against hepatitis B virus-associated hepatocellular carcinoma cells

“…These ligands might act as an agonist in specific cancer cells. In a microassay test, gene expression profiles differed between troglitazone and pioglitazone in HepG2 cells (33), suggesting that chemical structure determines biological endpoints.…”