Induction of Cytochrome P450 2A6 by Bilirubin in Human Hepatocytes


The influence of bilirubin on mRNA expression of cytochrome P450 (CYP), UDP-glucuronosyltransferase (UGT) and nuclear receptors in human hepatocytes was investigated. The treatment of the hepatocytes with 40 μg/mL bilirubin, which corresponds to hyperbilirubinemia, resulted in 1.7-fold increase of CYP2A6 mRNA compared to the vehicle control while CYP2A6 mRNA did not change after treatment with 1 μg/mL bilirubin, corresponding to physiologically normal level. No significant change of mRNA expression by 40 μg/mL bilirubin treatment was observed for CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP3A4 and CYP3A5, UGT1A1, UGT1A3, UGT1A6, UGT2B4, UGT2B7, UGT2B10 and UGT2B15, constitutive androstane receptor (CAR), pregnane X receptor (PXR), retinoid X receptor α (RXRα) and hepatocyte nuclear factor-4α (HNF-4α). The induction profile of bilirubin was different from that of rifampicin, a typical PXR activator. This study demonstrated that CYP2A6 can be induced by bilirubin in a concentration dependent manner.

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H. Tanii, Y. Shitara, M. Torii, S. Sekine, H. Iwata and T. Horie, "Induction of Cytochrome P450 2A6 by Bilirubin in Human Hepatocytes," Pharmacology & Pharmacy, Vol. 4 No. 2, 2013, pp. 182-190. doi: 10.4236/pp.2013.42026.

Conflicts of Interest

The authors declare no conflicts of interest.


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