Abstract
The constitutive androstane receptor (CAR, NR1I3) plays a key role in governing the transcription of numerous hepatic genes that involve xenobiotic metabolism/clearance, energy homeostasis, and cell proliferation. Thus, identification of novel human CAR (hCAR) modulators may not only enhance early prediction of drug-drug interactions but also offer potentially novel therapeutics for diseases such as metabolic disorders and cancer. In this study, we have generated a double stable cell line expressing both hCAR and a CYP2B6-driven luciferase reporter for quantitative high-throughput screening (qHTS) of hCAR modulators. Approximately 2800 compounds from the NIH Chemical Genomics Center Pharmaceutical Collection were screened employing both the activation and deactivation modes of the qHTS. Activators (115) and deactivators (152) of hCAR were identified from the primary qHTS, among which 10 agonists and 10 antagonists were further validated in the physiologically relevant human primary hepatocytes for compound-mediated hCAR nuclear translocation and target gene expression. Collectively, our results reveal that hCAR modulators can be efficiently identified through this newly established qHTS assay. Profiling drug collections for hCAR activity would facilitate the prediction of metabolism-based drug-drug interactions, and may lead to the identification of potential novel therapeutics.
Highlights
The constitutive androstane receptor (CAR, NR1I3) is well-recognized as a xenobiotic receptor that coordinates comprehensive metabolic responses in the liver when exposed to exogenous compounds including clinically used drugs and environmental chemicals[1,2,3]
A total of 2816 small molecule drugs from the NIH Chemical Genomics Center Pharmaceutical Collection (NPC) were profiled for their potential in modulating CAR signaling in agonist and antagonist modes, which led to the identification of many previously unreported human CAR (hCAR) modulators
2816 drugs from the NPC library were screened in agonist mode of the quantitative high-throughput screening (qHTS) assay, where 2.5 μ M of PK11195 was selected to repress the basal activity of hCAR, and CITCO, which yielded an EC50 of 1.11 μ M, was used as a positive control
Summary
The constitutive androstane receptor (CAR, NR1I3) is well-recognized as a xenobiotic receptor that coordinates comprehensive metabolic responses in the liver when exposed to exogenous compounds including clinically used drugs and environmental chemicals[1,2,3]. Identification of small molecules as CAR activators or deactivators is beneficial for early prediction of metabolism-based DDI and for the development of CAR modulators as potential drug candidates. While TCPOBOP- and phenobarbital (PB)-induced tumor promotion in mice is mCAR dependent, activation of hCAR by CITCO is associated with cell cycle arrest and enhanced apoptosis in human brain tumor stem cells[18] as well as in hCAR transgenic mice (data not shown). Together, these studies suggest that pronounced species variations may exist regarding the role of CAR in energy metabolism and cell proliferation. Selected hits were subjected to hCAR nuclear translocation and target gene expression experiments in human primary hepatocytes (HPH) for further validation
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call