Mechanistic Investigation of the Androgen Receptor DNA-Binding Domain Inhibitor Pyrvinium

Abstract

Pyrvinium was identified as the first small molecule inhibitor of the androgen receptor (AR) DNA-binding domain (DBD). It was also among the first small molecules shown to directly inhibit the activity of AR splice variants (ARVs), which has important clinical implications in the treatment of castration-resistant prostate cancer. Important questions about pyrvinium’s mechanism of action remain. Here, we demonstrate through mutational analysis that amino acids 609 and 612 are important for pyrvinium action. Nuclear magnetic resonance demonstrates a specific interaction between a soluble pyrvinium derivative and the AR DBD homodimer–DNA complex. Chromatin immunoprecipitation and electrophoretic mobility shift assay experiments demonstrate that, despite an interaction with this complex, pyrvinium does not alter the DNA-binding kinetics in either assay. AR immunoprecipitation followed by mass spectrometry was used to identify proteins whose interaction with AR is altered by pyrvinium. Several splicing factors, including DDX17, had reduced interactions with AR in the presence of pyrvinium. RNA sequencing of prostate cancer cells treated with pyrvinium demonstrated changes in splicing, as well as in several other pathways. However, pyrvinium did not alter the levels of ARVs in several prostate cancer cell lines. Taken together, our new data pinpoint the direct interaction between pyrvinium and AR DBD and shed light on the mechanism by which it inhibits AR transcriptional activity.

The Androgen Receptor in Prostate Cancer: Effect of Structure, Ligands and Spliced Variants on Therapy

“…However, although PP decreased prostate weight and did not affect lean body mass, it also decreased bone mineral density [ 121 ]. Later studies showed that several splicing factors, such as DDX17, had reduced interactions with AR in the presence of pyrvinium [ 122 ]. However, pyrvinium did not alter the levels of AR-Vs in several PCa cell lines [ 121 , 122 ].…”

“…Later studies showed that several splicing factors, such as DDX17, had reduced interactions with AR in the presence of pyrvinium [ 122 ]. However, pyrvinium did not alter the levels of AR-Vs in several PCa cell lines [ 121 , 122 ]. As a result, this drug, though promising, has not progressed to the stage of clinical investigation.…”

Virtual screening of potentially endocrine-disrupting chemicals against nuclear receptors and its application to identify PPARγ-bound fatty acids

“…In addition, only the ligand-binding domains (LBDs) of NRs were targeted in this study. However, it has been suggested that the DNA binding domains (DBDs) of NRs and even the DNA sites recognized by NRs can also be targeted by ligands (Brodie 2005 ; Meijsing et al 2009 ; Li et al 2014 ; Dalal et al 2014 ; Shizu et al 2018 ; Frank et al 2018 ; Pal et al 2019 ; Veras Ribeiro Filho et al 2019 ). Thus we expect that the application of our in silico method to these new molecular interfaces will also facilitate potential EDC prediction.…”

Breaking androgen receptor addiction of prostate cancer by targeting different functional domains in the treatment of advanced disease

“… BiAb 3E10-AR441 Bispecific antibody complementary to aa 302-318 in NTD [ 109 ] . AR-DBD targeting: inhibits AR interaction with DNA Pyridium pamoate Interacts with AR-DBD already bound to DNA to prevent RNA pol II recruitment [ 110 , 111 ] . VPC compounds Binds region under DBD P-box reducing interactions with AR and chromatin [ 112 , 113 ] .…”