Identification of human pregnane X receptor antagonists utilizing a high-throughput screening platform

Area of Science:

• Pharmacology
• Drug Metabolism
• Nuclear Receptors

Background:

• Pregnane X receptor (PXR) regulates drug metabolism and clearance.
• PXR also influences cell proliferation, apoptosis, immune response, and energy homeostasis.
• Identifying PXR modulators is vital for preventing drug-drug interactions, assessing toxicity, and developing therapeutics.

Purpose of the Study:

• To screen the NCATS Pharmacologically Active Chemical Toolbox (NPACT) library for PXR antagonists.
• To identify novel compounds that inhibit PXR activity.
• To evaluate the efficacy and potency of identified PXR antagonists.

Main Methods:

• Screened 5,099 compounds from the NPCT library for PXR antagonism.
• Confirmed 66 compounds as potential PXR antagonists.
• Assessed PXR inhibition by measuring CYP3A4 mRNA expression in HepaRG cells and using pharmacological assays in HepG2-CYP3A4-hPXR cells.

Main Results:

• Identified 94 potential PXR antagonists in the primary screen, with 66 confirmed.
• Selected 20 compounds, including gamma-secretase modulator 2 (GSM2) and fusidic acid, for further study.
• Confirmed GSM2 and fusidic acid as novel PXR antagonists, demonstrating concentration-dependent inhibition of CYP3A4 expression.

Conclusions:

• GSM2 and fusidic acid are identified as novel PXR antagonists.
• These findings provide valuable insights into potential drug-drug interactions.
• The identified compounds warrant further investigation for therapeutic potential and toxicity assessment.