RT Journal Article
SR Electronic
T1 CYP3A4 Catalytic Activity Is Induced in Confluent Huh7 Hepatoma Cells
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 995
OP 1002
DO 10.1124/dmd.110.032367
VO 38
IS 6
A1 Sivertsson, Louise
A1 Ek, Monica
A1 Darnell, Malin
A1 Edebert, Irene
A1 Ingelman-Sundberg, Magnus
A1 Neve, Etienne P. A.
YR 2010
UL http://dmd.aspetjournals.org/content/38/6/995.abstract
AB Drug-induced hepatotoxicity is an important cause for disapproval, limitations of use, or withdrawal of drugs, and there is a high need for reproducible in vitro systems that can predict such toxicity. In this study, we show that confluent growth of the human hepatoma cell line Huh7 up to 5 weeks results in increased gene expression of several cytochromes P450 (P450s), UDP-glucuronosyltransferases, transporters, transcription factors, and several liver-specific genes, as measured by low-density array. The most striking effect was seen for CYP3A4 expression. Western blot analysis revealed increased amounts of CYP3A4 together with increased levels of NADPH-P450 reductase, cytochrome b5, and albumin with prolonged time of confluence. By using the CYP3A4-specific substrates luciferin 6′ benzyl ether, testosterone, and midazolam, we could confirm that the increased CYP3A4 gene expression also was accompanied by a similar increase in catalytic activity, inhibitable by the CYP3A4-selective inhibitor ketoconazole. The CYP3A4 activity in confluent cells was also inducible by rifampicin. Finally, the cell system could support the CYP3A4-dependent hepatotoxic activation of aflatoxin B1, which was effectively inhibited by ketoconazole. Our results show that Huh7 cells grown confluent differentiate into a more metabolically competent cell line, especially with regard to CYP3A4. Copyright © 2010 by The American Society for Pharmacology and Experimental Therapeutics