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Megestrol acetate is a specific inducer of CYP3A4 mediated by human pregnane X receptor

Yakun Chen1, Yong Tang1, Jeffrey Z Nie1

  • 1Department of Medical Microbiology, Immunology and Cell Biology, Southern Illinois University School of Medicine and Simmons Cancer Institute, Springfield, IL, 62794-9626, USA.

Cancer Chemotherapy and Pharmacology
|September 15, 2021
PubMed
Abstract

Insights

Megestrol acetate significantly induces CYP3A4 enzyme activity by activating the human pregnane X receptor (hPXR). This induction can lead to potential drug interactions when megestrol acetate is used with other CYP3A4 substrate medications.

Area of Science:

  • Pharmacology
  • Drug Metabolism
  • Molecular Biology

Background:

  • Megestrol acetate, a synthetic progestogen, is used for cancer treatment and managing cachexia.
  • Its potential to interact with other drugs is not well understood.
  • Understanding its effects on drug-metabolizing enzymes is crucial for patient safety.

Purpose of the Study:

  • To investigate the regulation of drug-metabolizing enzymes by megestrol acetate.
  • To determine if megestrol acetate affects the expression or activity of key metabolic enzymes.
  • To elucidate the molecular mechanisms underlying these effects.

Main Methods:

  • Human hepatocytes and HepG2 cells were treated with megestrol acetate.
  • Gene expression was analyzed using PCR arrays and reporter gene assays (CYP3A4).
  • Enzyme activity was assessed via HPLC analysis of nifedipine metabolites.
  • Ligand binding assays and electrophoretic mobility shift assays were used to study interactions with the human pregnane X receptor (hPXR).

Main Results:

  • Megestrol acetate significantly induced CYP3A4 (cytochrome P450 3A4) levels and activity by over 4-fold in human hepatocytes and HepG2 cells.
  • This induction was mediated through the activation of the human pregnane X receptor (hPXR).
  • Mechanism studies confirmed that megestrol acetate binds to the hPXR ligand-binding domain, enhancing cofactor recruitment.

Conclusions:

  • Megestrol acetate is a specific inducer of CYP3A4 via hPXR activation.
  • This finding highlights the potential for megestrol acetate to cause drug interactions.
  • Caution is advised when co-administering megestrol acetate with drugs metabolized by CYP3A4.
Keywords:
CYP3A4Drug metabolizing enzymesMegestrol acetatePXR

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