Targeted Degradation of Androgen Receptor by VNPP433-3β in Castration-Resistant Prostate Cancer Cells Implicates Interaction with E3 Ligase MDM2 Resulting in Ubiquitin-Proteasomal Degradation

Elizabeth Thomas; Retheesh S Thankan; Puranik Purushottamachar; David J Weber; Vincent C O Njar

doi:10.3390/cancers15041198

Targeted Degradation of Androgen Receptor by VNPP433-3β in Castration-Resistant Prostate Cancer Cells Implicates Interaction with E3 Ligase MDM2 Resulting in Ubiquitin-Proteasomal Degradation

Cancers (Basel). 2023 Feb 14;15(4):1198. doi: 10.3390/cancers15041198.

Authors

Elizabeth Thomas^{1

2}, Retheesh S Thankan^{1

2

3}, Puranik Purushottamachar^{1

2}, David J Weber^{2

4

5}, Vincent C O Njar^{1

2

5}

Affiliations

¹ Department of Pharmacology, University of Maryland School of Medicine, 685 West Baltimore Street, Baltimore, MD 21201, USA.
² The Center for Biomolecular Therapeutics, University of Maryland School of Medicine, 685 West Baltimore Street, Baltimore, MD 21201, USA.
³ Isoprene Pharmaceuticals, Inc., 801 W Baltimore Street, Suite 502J, Baltimore, MD 21201, USA.
⁴ Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
⁵ Marlene and Stewart Greenebaum Comprehensive Cancer Center, University of Maryland School of Medicine, 685 West Baltimore Street, Baltimore, MD 21201, USA.

Abstract

Targeted protein degradation is a fast-evolving therapeutic strategy to target even the traditionally undruggable target proteins. Contrary to the traditional small-molecule inhibitors of enzyme or receptor antagonists that bind the active site pockets in the target protein, molecular glue degraders facilitate interaction of target proteins with E3 ubiquitin ligases by stabilizing the ternary complex and induce physical proximity, thereby triggering ubiquitination and subsequent proteasomal degradation. AR plays a key role in all stages of prostate cancer. It is activated by the binding of androgenic hormones and transcriptionally regulates multiple genes including the ones that regulate cell cycle. Using HiBiT CRISPR cell line, biochemical methods, and RNA sequencing, we report the potential role of VNPP433-3β, the next generation galeterone analog as molecular glue that brings together AR, the key driver of prostate cancer and MDM2, an E3 ubiquitin ligase leading to ubiquitination and subsequent degradation of f-AR and AR-V7 in prostate cancer cells.

Keywords: HiBiT CRISPR cell; androgen receptor (f-AR/AR-V7) degrader; molecular glue; prostate cancer; targeted protein degradation.

Grants and funding

This work was supported in part by grants from the National Institutes of Health (NIH) and the National Cancer Institute (NCI) R01CA224696 to VCON.