Fig. 1

Changes in the expression and activity of CYP enzymes in HepaRG cells induced by the CHIR treatment. The expression of the CYP mRNAs and enzymatic activities of CYPs (CYP2B6, CYP1A2, CYP2E1, and CYP3A4) were analyzed in CHIR-treated HepaRG cells. a Fully differentiated HepaRG cells were exposed to various concentrations of CHIR. The relative levels of CYPs, AXIN2, and ALB (albumin) mRNAs in HepaRG cells were examined after 3 days of CHIR treatment using qRT-PCR. The relative level of ALB was calculated in the HepaRG cells before and after CHIR treatment comparing with THLE2 cells. The basal expression level of ALB mRNA in HepaRG cells was remarkably greater than that of THLE2 cells (b) A microarray analysis was performed using HepaRG cells that had been treated with 9 μM CHIR for 3 days. The heatmap of genes involved in drug metabolism was analyzed using Gene-E software, and canonical pathways of differentially expressed genes (2-fold, P < 0.01) were analyzed using IPA software. c Enzymatic activities of CYPs in HepaRG cells treated with CHIR for up to 10 days. The activities of CYP1A2 and CYP3A4 were measured using the P450-Glo CYP assay, and the CYP activity values were normalized to cell number by dividing the P450-Glo luminescence values by the CCK-8 absorbance values, according to the manufacturer’s instructions. CYP2E1 activity was measured by determining the conversion of chlorzoxazone to OH-chlorzoxazone using HPLC-tandem mass spectrometry. All data are presented as the means ± SD. *P < 0.05 and **P < 0.01 compared with the untreated group at each time point; Student’s t-test