POSTER ABSTRACT / DETAILS:
Human pluripotent stem cell (hPSC)-derived hepatocyte has been considered to be the most promising cell model for hepatotoxicity testing. However, it has not been well predictive because of its low expression and activity of drug metabolizing enzymes (DMEs).
In this study, we measured mRNA levels of a variety of DMEs and their major regulators including AHR, CAR and PXR during in vitro hepatic differentiation.
The mRNA expression levels of most DMEs regulated by CAR and PXR were considerably low in hPSC-derived hepatocytes. On the other hand, the mRNA expression levels of CYP1A1 and CYP1B1 regulated by AHR were comparable to those seen in human adult hepatocytes. Moreover, AHR and its signaling components were active in hPSC-derived hepatocytes, whereas the expression of CAR and PXR mRNA was weak or negligible. In addition, to demonstrate the functional utility of AHR signaling in hPSC-derived hepatocyte, we measured the induction of several AHR downstream target genes in response to well-known AHR agonists.
Quantitative real-time polymerase chain reaction (qRT-CPR) analysis revealed strong induction of both CYP1A1 and CYP1B1 by benzo(a)pyrene (BaP), 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 3-methylcholanthrene (3-MC), and 2-(1′H-indole-3′-carbonyl)-thiazole-4-carboxylicacid methyl ester (ITE). Furthermore, 6, 2′, 4′-trimethoxyflavone (TMF), a known AHR antagonist, exhibited strong inhibitory effect on the transcriptional activity associated with AHR in hPSC-derived hepatocytes. These results indicated that hPSC-derived hepatocytes can be useful model for screening toxic substances triggering human AHR signaling pathway.