Abstract
The pregnane X receptor (PXR) binds xenobiotics and regulates the expression of several drug-metabolizing enzymes and transporters. Human PXR (hPXR) activation and CYP3A4 induction can be involved in drug-drug interactions, resulting in reduced efficacy or increased toxicity. However, there are known species-specific differences with regard to PXR activation that should be taken into account when animal PXR data are extrapolated to humans. We profiled 2816 clinically used drugs from the National Institutes of Health Chemical Genomics Center Pharmaceutical Collection for their ability to activate hPXR and rat PXR (rPXR) at the cellular level, induce human CYP3A4 at the cellular level, and bind human PXR at the protein level. From 6 to 11% of drugs were identified as active across the four assays, which included assay-specific and pan-active compounds. The lowest concordance was observed between the hPXR and rPXR assays, and many compounds active in both assays nonetheless demonstrated significant potency differences between species. Analysis based on clustering potency values demonstrated the greatest activity correlation between the hPXR activation and CYP3A4 induction assays. Structure-activity relationship analysis identified chemical scaffolds that were pan-active (e.g., dihydropyridine calcium channel blockers) and others that were uniquely active in individual assays (e.g., steroids and fatty acids). These results provide important information on PXR activation by clinically used drugs, highlight the species specificity of PXR activation by xenobiotics, and provide a means of prioritizing compounds for follow-up studies and optimization efforts.
Footnotes
- Received June 22, 2010.
- Accepted October 21, 2010.
This research was supported in part by the Intramural Research Program of the National Institutes of Health National Human Genome Research Institute.
Article, publication date, and citation information can be found at http://dmd.aspetjournals.org.
doi:10.1124/dmd.110.035105.
↵ The online version of this article (available at http://dmd.aspetjournals.org) contains supplemental material.
ABBREVIATIONS:
- PXR
- pregnane X receptor
- NR
- nuclear receptor
- P450
- cytochrome P450
- GST
- glutathione transferase
- LBD
- ligand binding domain
- hPXR
- human pregnane X receptor
- qHTS
- quantitative high-throughput screening
- rPXR
- rat pregnane X receptor
- PXRE
- PXR response element
- RXR
- retinoid X receptor
- NPC
- National Institutes of Health Chemical Genomics Center Pharmaceutical Collection
- DMSO
- dimethyl sulfoxide
- FRD
- flying reagent dispenser
- TR-FRET
- time-resolved fluorescence resonance energy transfer
- SR12813
- 3,5-di-tert-butyl-4-hydroxystyrene-β,β-diphosphonic acid tetraethyl ester
- CRC
- concentration response curve
- SAR
- structure-activity relationship
- LC
- liquid chromatography
- MS
- mass spectrometry
- TFA
- trifluoroacetic acid
- CDK
- cyclin-dependent kinase
- PPAR-γ
- peroxisome proliferator-activated receptor.
- Copyright © 2011 by The American Society for Pharmacology and Experimental Therapeutics
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