An androgen receptor N-terminal domain antagonist for treating prostate cancer
Jae-Kyung Myung, Carmen A. Banuelos, Javier Garcia Fernandez, Nasrin R. Mawji, Jun Wang, Amy H. Tien, Yu Chi Yang, Iran Tavakoli, Simon Haile, Kate Watt, Iain J. McEwan, Stephen Plymate, Raymond J. Andersen, Marianne D. Sadar
Jae-Kyung Myung, Carmen A. Banuelos, Javier Garcia Fernandez, Nasrin R. Mawji, Jun Wang, Amy H. Tien, Yu Chi Yang, Iran Tavakoli, Simon Haile, Kate Watt, Iain J. McEwan, Stephen Plymate, Raymond J. Andersen, Marianne D. Sadar
View: Text | PDF
Research Article Oncology

An androgen receptor N-terminal domain antagonist for treating prostate cancer

Abstract

Hormone therapies for advanced prostate cancer target the androgen receptor (AR) ligand-binding domain (LBD), but these ultimately fail and the disease progresses to lethal castration-resistant prostate cancer (CRPC). The mechanisms that drive CRPC are incompletely understood, but may involve constitutively active AR splice variants that lack the LBD. The AR N-terminal domain (NTD) is essential for AR activity, but targeting this domain with small-molecule inhibitors is complicated by its intrinsic disorder. Here we investigated EPI-001, a small-molecule antagonist of AR NTD that inhibits protein-protein interactions necessary for AR transcriptional activity. We found that EPI analogs covalently bound the NTD to block transcriptional activity of AR and its splice variants and reduced the growth of CRPC xenografts. These findings suggest that the development of small-molecule inhibitors that bind covalently to intrinsically disordered proteins is a promising strategy for development of specific and effective anticancer agents.

Authors

Jae-Kyung Myung, Carmen A. Banuelos, Javier Garcia Fernandez, Nasrin R. Mawji, Jun Wang, Amy H. Tien, Yu Chi Yang, Iran Tavakoli, Simon Haile, Kate Watt, Iain J. McEwan, Stephen Plymate, Raymond J. Andersen, Marianne D. Sadar

×

Figure 4

Chemical mechanism of EPI binding to AF1.

Options: View larger image (or click on image) Download as PowerPoint
Chemical mechanism of EPI binding to AF1. (A) AF1 protein was incubated ...
(A) AF1 protein was incubated with EPI-054, EPI-063 (inactive), or DMSO (vehicle) at the indicated molar ratios on ice for 1 hour or 20 hours, prior to Click-chemistry for fluorescein labeling, SDS-PAGE, and detection of fluorescein-labeled probe covalently bound to AF1. Quantification of fluorescein band intensity, normalized to Coomassie blue bands, is also shown. The value from each EPI condition was normalized to the value of DMSO for each individual experiment (n = 4 separate experiments). (B) AF1 protein was incubated with DMSO, EPI-054, EPI-063, EPI-056, or EPI-096 (AF1/EPI 1:3 molar ratio) at 25°C for 18 hours, prior to Click-chemistry for fluorescein labeling, SDS-PAGE, and detection of fluorescein-labeled probe covalently bound to AF1. (C) EPI analogs do not alkylate glutathione or mercaptoethanol. A mixture of glutathione (127 μM) and EPI-001 (25 μM), or a mixture of EPI-001 (55 μM) and 2-mercaptoethanol (155 μM), was monitored by proton and carbon NMR over a period of 7 days. There was no evidence for reaction of EPI-001 with either glutathione or mercaptoethanol. (D) Steady-state spectra of 1 μM recombinant wild-type AF1 protein in buffer, buffer plus 2.9 μM EPI-001, buffer plus 6 M urea, or buffer plus 6 M urea and 2.9 μM EPI-001. (E) Prostate weights from mice treated with DMSO (i.v.), EPI-093 or EPI-002 (50 mg/kg body weight; i.v.), or bicalutamide (10 mg/kg body weight; gavage daily) for 14 days. Data are mean ± SEM. There was no significant difference between EPI and bicalutamide. #P < 0.001.