Metformin suppresses pregnane X receptor (PXR)-regulated transactivation of CYP3A4 gene

Lucie Krausova, Lucie Stejskalova, Hongwei Wang, Radim Vrzal, Zdenek Dvorak, Sridhar Mani, Petr Pavek

Research output: Contribution to journalArticle

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Abstract

Metformin is widely used in the treatment of type-2 diabetes. The pleotropic effects of metformin on glucose and lipid metabolism have been proposed to be mediated by the activation of AMP-activated protein kinase (AMPK) and the subsequent up-regulation of small heterodimer partner (SHP). SHP suppresses the functions of several nuclear receptors involved in the regulation of hepatic metabolism, including pregnane X receptor (PXR), which is referred to as a "master regulator" of drug/xenobiotic metabolism. In this study, we hypothesize that metformin suppresses the expression of CYP3A4, a main detoxification enzyme and a target gene of PXR, due to SHP up-regulation. We employed various gene reporter assays in cell lines and qRT-PCR in human hepatocytes and in Pxr -/- mice. We show that metformin dramatically suppresses PXR-mediated expression of CYP3A4 in hepatocytes. Consistently, metformin significantly suppressed the up-regulation of Cyp3a11 mRNA in the liver and intestine of wild-type mice, but not in Pxr -/- mice. A mechanistic investigation of the phenomenon showed that metformin does not significantly up-regulate SHP in human hepatocytes. We further demonstrate that AMPK activation is not involved in this process. We show that metformin disrupts PXR's interaction with steroid receptor coactivator-1 (SRC1) in a two-hybrid assay independently of the PXR ligand binding pocket. Metformin also inhibited vitamin D receptor-, glucocorticoid receptor- and constitutive androstane receptor (CAR)-mediated induction of CYP3A4 mRNA in human hepatocytes. We show, therefore, a suppressive effect of metformin on PXR and other ligand-activated nuclear receptors in transactivation of the main detoxification enzyme CYP3A4 in human hepatocytes.

Original languageEnglish (US)
Pages (from-to)1771-1780
Number of pages10
JournalBiochemical Pharmacology
Volume82
Issue number11
DOIs
StatePublished - Dec 1 2011

Fingerprint

Cytochrome P-450 CYP3A
Metformin
Transcriptional Activation
Genes
Hepatocytes
Up-Regulation
Detoxification
AMP-Activated Protein Kinases
Cytoplasmic and Nuclear Receptors
Metabolism
Assays
Nuclear Receptor Coactivator 1
Chemical activation
Ligands
pregnane X receptor
Messenger RNA
Two-Hybrid System Techniques
Calcitriol Receptors
Liver
Glucocorticoid Receptors

Keywords

  • AMPK
  • Cytochrome P450
  • Induction
  • Metformin
  • PXR

ASJC Scopus subject areas

  • Pharmacology
  • Biochemistry

Cite this

Metformin suppresses pregnane X receptor (PXR)-regulated transactivation of CYP3A4 gene. / Krausova, Lucie; Stejskalova, Lucie; Wang, Hongwei; Vrzal, Radim; Dvorak, Zdenek; Mani, Sridhar; Pavek, Petr.

In: Biochemical Pharmacology, Vol. 82, No. 11, 01.12.2011, p. 1771-1780.

Research output: Contribution to journalArticle

Krausova, L, Stejskalova, L, Wang, H, Vrzal, R, Dvorak, Z, Mani, S & Pavek, P 2011, 'Metformin suppresses pregnane X receptor (PXR)-regulated transactivation of CYP3A4 gene', Biochemical Pharmacology, vol. 82, no. 11, pp. 1771-1780. https://doi.org/10.1016/j.bcp.2011.08.023
Krausova, Lucie ; Stejskalova, Lucie ; Wang, Hongwei ; Vrzal, Radim ; Dvorak, Zdenek ; Mani, Sridhar ; Pavek, Petr. / Metformin suppresses pregnane X receptor (PXR)-regulated transactivation of CYP3A4 gene. In: Biochemical Pharmacology. 2011 ; Vol. 82, No. 11. pp. 1771-1780.
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AU - Krausova, Lucie

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AU - Wang, Hongwei

AU - Vrzal, Radim

AU - Dvorak, Zdenek

AU - Mani, Sridhar

AU - Pavek, Petr

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AB - Metformin is widely used in the treatment of type-2 diabetes. The pleotropic effects of metformin on glucose and lipid metabolism have been proposed to be mediated by the activation of AMP-activated protein kinase (AMPK) and the subsequent up-regulation of small heterodimer partner (SHP). SHP suppresses the functions of several nuclear receptors involved in the regulation of hepatic metabolism, including pregnane X receptor (PXR), which is referred to as a "master regulator" of drug/xenobiotic metabolism. In this study, we hypothesize that metformin suppresses the expression of CYP3A4, a main detoxification enzyme and a target gene of PXR, due to SHP up-regulation. We employed various gene reporter assays in cell lines and qRT-PCR in human hepatocytes and in Pxr -/- mice. We show that metformin dramatically suppresses PXR-mediated expression of CYP3A4 in hepatocytes. Consistently, metformin significantly suppressed the up-regulation of Cyp3a11 mRNA in the liver and intestine of wild-type mice, but not in Pxr -/- mice. A mechanistic investigation of the phenomenon showed that metformin does not significantly up-regulate SHP in human hepatocytes. We further demonstrate that AMPK activation is not involved in this process. We show that metformin disrupts PXR's interaction with steroid receptor coactivator-1 (SRC1) in a two-hybrid assay independently of the PXR ligand binding pocket. Metformin also inhibited vitamin D receptor-, glucocorticoid receptor- and constitutive androstane receptor (CAR)-mediated induction of CYP3A4 mRNA in human hepatocytes. We show, therefore, a suppressive effect of metformin on PXR and other ligand-activated nuclear receptors in transactivation of the main detoxification enzyme CYP3A4 in human hepatocytes.

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KW - Induction

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KW - PXR

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