Structural and Functional Studies of Androgen Receptor and Its Cofactors
Technical Report,15 May 2018,14 May 2019
Sloan Kettering Institute for Cancer Research New York United States
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The androgen receptor AR is the master transcription factor that governs prostate identity. In castration resistant prostate cancer CRPC, AR signaling is hyperactivated and drives advanced disease. AR inhibitors are used to treat CRPC though initially effective, half of patients eventually acquire resistance through further AR amplification, necessitating a need for more potent AR inhibitors. One novel approach is to disrupt disease-specific cofactor interactions that activate AR. Normally not expressed in prostate, the ETS transcription factor ERG is overexpressed in over half of patients with CRPC, and expands the AR transcriptome through a process that is not fully understood. Though one of these avenues may be through a direct AR-ERG interaction, molecular details are lacking primarily due to difficulty in isolating active AR protein. We optimized AR expression and purification, and reconstituted an ARERGDNA complex using recombinant proteins. We found that in the absence of ERG, AR exhibits N-terminal dependent autoinhibition. However, association with ERG stimulates ARs ability to bind DNA through a direct interaction within the ERG ETS domain. This stimulation is maintained in the presence of the AR inhibitor, enzalutamide. These findings may extend to other ETS factors whose expression is altered in CRPC. Finally, we have initiated structural studies of this complex using single particle cryo-electron microscopy to resolve the structure of multidomain AR and define the region of interaction between AR and ERG.
- Medicine and Medical Research