PT  - JOURNAL ARTICLE
AU  - Hariparsad, Niresh
AU  - Carr, Brian A.
AU  - Evers, Raymond
AU  - Chu, Xiaoyan
TI  - Comparison of Immortalized Fa2N-4 Cells and Human Hepatocytes as in Vitro Models for Cytochrome P450 Induction
AID  - 10.1124/dmd.108.020677
DP  - 2008 Jun 01
TA  - Drug Metabolism and Disposition
PG  - 1046--1055
VI  - 36
IP  - 6
4099  - http://dmd.aspetjournals.org/content/36/6/1046.short
4100  - http://dmd.aspetjournals.org/content/36/6/1046.full
SO  - Drug Metab Dispos2008 Jun 01; 36
AB  - Fa2N-4 cells have been proposed as a tool to identify CYP3A4 inducers. To evaluate whether Fa2N-4 cells are a reliable surrogate for cryopreserved human hepatocytes, we assessed the basal mRNA expression of 64 drug disposition genes in Fa2N-4 cells. Significant differences were found in the expression of major drug-metabolizing enzymes, nuclear receptors, and transporters between both cell types. Importantly, the expression of constitutive androstane receptor (CAR) and several hepatic uptake transporters was significantly lower (>50-fold) in Fa2N-4 cells, whereas the expression of pregnane X-receptor (PXR) and aryl hydrocarbon receptor (AhR) was similar between Fa2N-4 cells and human hepatocytes. By using an optimized induction assay for Fa2N-4 cells, CYP3A4 induction by rifampicin, the prototypical PXR activator, increased from 1.5- to 7-fold at the level of functional activity. With nine selected compounds, which are known inducers of CYP3A4 either via activation of PXR, CAR, or both, we evaluated CYP3A4 and CYP2B6 mRNA induction using Fa2N-4 cells and human hepatocytes. No response was observed in Fa2N-4 cells treated with the selective CAR activators 6-(4-chlorophenyl)imidazo[2,1-b][1,3]-thiazole-5-carbaldehyde O-(3,4-dichlorobenzyl)oxime and artemisinin. CYP3A4 and CYP2B6 induction in Fa2N-4 cells were also low for phenytoin, phenobarbital, and efavirenz, which are dual activators of PXR/CAR. This finding was in agreement with the lack of expression of CAR. The EC50 value for rifampicin-mediated CYP3A4 induction was 10-fold higher than that in human hepatocytes. This result could be attributed to the low expression of hepatic organic anion-transporting polypeptides OATP1B1 and OATP1B3 in Fa2N-4 cells. In summary, our findings identify limitations of Fa2N-4 cells as a predictive induction model. The American Society for Pharmacology and Experimental Therapeutics