Cytotoxic Doses of Ketoconazole Affect Expression of a Subset of Hepatic Genes

Abstract

Ketoconazole is a widely prescribed antifungal drug, which has also been investigated as an anticancer therapy in both clinical and pre-clinical settings. However, severe hepatic injuries were reported to be associated with the use of ketoconazole, even in patients routinely monitored for their liver functions. Several questions concerning ketoconazole-induced hepatic injury remain unanswered, including (1) does ketoconazole alter cytochrome P450 expression at the transcriptional level?, (2) what types of gene products responsible for cytotoxicity are induced by ketoconazole?, and (3) what role do the major metabolites of ketoconazole play in this pathophysiologic process? A mouse model was employed to investigate hepatic gene expression following hepatotoxic doses of ketoconazole. Hepatic gene expression was analyzed using a toxicogenomic microarray platform, which is comprised of cDNA probes generated from livers exposed to various hepatoxicants. These hepatoxicants fall into five well-studied toxicological categories: peroxisome proliferators, aryl hydrocarbon receptor agonists, noncoplanar polychlorinated biphenyls, inflammatory agents, and hypoxia-inducing agents. Nine genes encoding enzymes involved in Phase I metabolism and one Phase II enzyme (glutathione S-transferase) were found to be upregulated. Serum amyloid A (SAA1/2) and hepcidin were the only genes that were downregulated among the 2364 genes assessed. In vitro cytotoxicity and transcription analyses revealed that SAA and hepcidin are associated with the general toxicity of ketoconazole, and might be usefully explored as generalized surrogate markers of xenobiotic-induced hepatic injury. Finally, it was shown that the primary metabolite of ketoconazole (de-N-acetyl ketoconazole) is largely responsible for the hepatoxicity and the downregulation of SAA and hepcidin.

We are grateful to Dr. Chris Bradfield at University of Wisconsin for the microarray analyses. We thank Michele Lemieux and Sophie Smith for their technical assistance, as well as Drs. T. Cyr, P Zaphiropoulos, and R. Rodriguez for helpful discussions. Frank Yin is acknowledged for statistical analysis. WLC, CO, LW, MAH, RAA, CFT, ASW, and XL are involved in the experiment design, data interpretation, and writing of the article. CO, LL, BJ, CLW, and JAM conducted experiments and collected data. The authors declare no conflicts of financial interests. This project was funded by the Canadian Regulatory Biotechnology Initiative of the Government of Canada. ASW was supported in part by grant 1 P30 ES013508-01A1 from the National Institute of Environmental Health Sciences (NIEHS), NIH.