Inhibiting androgen receptor splice variants with cysteineselective irreversible covalent inhibitors to treat prostate cancer

Thirumagal Thiyagarajan, Suriyan Ponnusamy, Dong Jin Hwang, Yali He, Sarah Asemota, Kirsten L. Young, Daniel L. Johnson, Vera Bocharova, Weidong Zhou, Abhinav K. Jain, Emanuel F. Petricoin, Zheng Yin, Lawrence M. Pfeffer, Duane D. Miller, Ramesh Narayanan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Androgen receptor (AR) and its splice variants (AR-SVs) promote prostate cancer (PCa) growth by orchestrating transcriptional reprogramming. Mechanisms by which the low complexity and intrinsically disordered primary transactivation domain (AF-1) of AR and AR-SVs regulate transcriptional programming in PCa remains poorly defined. Using omics, live and fixed fluorescent microscopy of cells, and purified AF-1 and AR-V7 recombinant proteins we show here that AF-1 and the AR-V7 splice variant form molecular condensates by liquid-liquid phase separation (LLPS) that exhibit disorder characteristics such as rapid intracellular mobility, coactivator interaction, and euchromatin induction. The LLPS and other disorder characteristics were reversed by a class of small-molecule-selective AR-irreversible covalent antagonists (SARICA) represented herein by UT-143 that covalently and selectively bind to C406 and C327 in the AF-1 region. Interfering with LLPS formation with UT-143 or mutagenesis resulted in chromatin condensation and dissociation of AR-V7 interactome, all culminating in a transcriptionally incompetent complex. Biochemical studies suggest that C327 and C406 in the AF-1 region are critical for condensate formation, AR-V7 function, and UT-143's irreversible AR inhibition. Therapeutically, UT-143 possesses drug-like pharmacokinetics and metabolism properties and inhibits PCa cell proliferation and tumor growth. Our work provides critical information suggesting that clinically important AR-V7 forms transcriptionally competent molecular condensates and covalently engaging C327 and C406 in AF-1, dissolves the condensates, and inhibits its function. The work also identifies a library of AF-1-binding AR and AR-SV-selective covalent inhibitors for the treatment of PCa.

Original languageEnglish
Article numbere2211832120
JournalProceedings of the National Academy of Sciences of the United States of America
Volume120
Issue number1
DOIs
StatePublished - 3 Jan 2023
Externally publishedYes

Keywords

  • AR splice variants (AR-SVs)
  • Androgen receptor (AR)
  • Selective AR irreversible covalent antagonists (SARICA)
  • castration-resistant prostate cancer (CRPC)
  • liquid-liquid phase separation (LLPS)

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