Abstract 5729: Dynamic phase separation of the androgen receptor and its coactivators to regulate gene expression

Abstract

Abstract Numerous cancers, including prostate cancer (PCa), have been shown to be addicted to transcription programs driven by specific genomic sites known as superenhancers (SEs). Recently, it has been proposed that the robust transcription of genes at such SEs is enabled by the formation of phase-separated condensates by transcription factors and coactivators with intrinsically disordered regions. The androgen receptor (AR), the main oncogenic driver in PCa, contains large disordered regions and is co-recruited with the transcriptional coactivator MED1 to SEs in androgen-dependent prostate cancer cells, thereby promoting oncogenic transcriptional programs. In this work, we show that AR-rich, liquid-like foci form in prostate cancer models upon androgen stimulation. We reveal that foci formation correlates with AR transcriptional activity, which can be modulated by changing cellular foci content genetically or chemically. We also demonstrate that the transcriptional coactivator MED1 plays an essential role in the formation of transcriptionally active AR-rich foci and that AR antagonists that block cofactor recruitment or DNA binding hinder foci formation and thus AR transcriptional activity. The liquid like properties of the condensates were also validated in-vitro by using recombinant AR protein. Using clinical specimens, we detected the interaction between AR and MED1 in advanced forms of prostate cancer and not in benign tissues. These results suggest that enhanced compartmentalization of AR and coactivators at SEs may play an important role in the activation of oncogenic transcription programs in androgen-dependent PCa. A better understanding of the assembly and the regulation of these AR-rich compartments may provide novel therapeutic options for PCa by targeting downstream events of androgen activation and DNA binding of AR. Citation Format: Fan Zhang, Maitree Biswas, Joseph Lee, Shreyas Lingadahalli, Samantha Wong, Christopher Wells, Neetu Saxena, Bei Sun, Ana K. Parra-Nuñez, Christophe Sanchez, Jane Foo, Novia Chan, Lauren Ung, Nabeel Khan, Umut Berkay Altıntaş, Jennifer M. Bui, Yuzhuo Wang, Ladan Fazli, Paul S. Rennie, Nathan Lack, Artem Cherkasov, Martin E. Gleave, Joerg Gsponer, Nada Lallous. Dynamic phase separation of the androgen receptor and its coactivators to regulate gene expression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5729.