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Published on: January 22, 2019
Physachenolide C is a Potent, Selective BET Inhibitor
Christopher J Zerio1, Jared Sivinski1, E M Kithsiri Wijeratne2
1College of Pharmacy, Department of Pharmacology and Toxicology, University of Arizona, 1703 E. Mabel Street, PO Box 210207, Tucson, Arizona 85721, United States.
Physachenolide C (PCC), a natural product, inhibits bromodomain and extra-terminal domain (BET) proteins, showing potent anti-cancer effects in prostate cancer cells by promoting BET protein degradation.
Area of Science:
- Chemical Biology
- Molecular Oncology
- Natural Products Chemistry
Background:
- Bromodomain and extra-terminal domain (BET) proteins (BRD2, BRD3, BRD4) are epigenetic readers regulating gene transcription.
- Dysregulation of BET proteins is implicated in various cancers, including prostate cancer (PC).
- Natural products offer a rich source for novel therapeutic agents targeting cancer pathways.
Purpose of the Study:
- To identify cellular targets of the natural product physachenolide C (PCC).
- To characterize the inhibitory mechanism of PCC against BET proteins.
- To evaluate the anti-cancer efficacy of PCC in prostate cancer models.
Main Methods:
- Biotinylated pulldown assays to identify protein interactors.
- BROMOscan bromodomain profiling and biochemical assays.
- X-ray crystallography and NMR spectroscopy for structural analysis.
- Cytotoxicity assays in prostate cancer cell lines.
Main Results:
- PCC identified BET proteins (BRD2, BRD3, BRD4) as potential cellular targets.
- PCC acts as a BET inhibitor with selectivity for bromodomain (BD)-1 of BRD3 and BRD4.
- Structural studies revealed specific interactions underlying PCC's potency and selectivity.
- PCC functions as a molecular glue, inducing proteasome-mediated degradation of BRD3 and BRD4.
- PCC demonstrated superior cytotoxicity compared to (+)-JQ1 in diverse prostate cancer cell lines.
Conclusions:
- PCC is a potent BET inhibitor and molecular glue targeting BRD3 and BRD4.
- PCC exhibits significant anti-cancer activity in prostate cancer cells, independent of AR signaling.
- PCC represents a promising therapeutic lead for prostate cancer treatment.
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