The clinical success of combined androgen deprivation therapy (ADT) and radiation therapy (RT) in prostate cancer (PCa) created interest in understanding the mechanistic links between androgen receptor (AR) signaling and the DNA damage response (DDR). Convergent data have led to a model where AR both regulates, and is regulated by, the DDR. Integral to this model is that the AR regulates the transcription of DDR genes both at steady state and in response to ionizing radiation (IR). In this study, we sought to determine which immediate transcriptional changes are induced by IR in an AR-dependent manner. Using PRO-seq to quantify changes in nascent RNA transcription in response to IR, the AR antagonist enzalutamide, or the combination of the two, we find that enzalutamide treatment significantly decreased expression of canonical AR target genes but had no effect on DDR gene sets in PCa cells. Surprisingly, we also found that the AR is not a primary regulator of DDR genes either in response to IR or at steady state in asynchronously growing PCa cells. Implications: Our data indicate that the clinical benefit of combining ADT with RT is not due to direct AR regulation of DDR gene transcription, and that the field needs to consider alternative mechanisms for this clinical benefit.
Molecular cancer research : MCR. 2023 Sep 12 [Epub ahead of print]
Sylwia Hasterok, Thomas G Scott, Devin G Roller, Adam Spencer, Arun B Dutta, Kizhakke M Sathyan, Daniel E Frigo, Michael J Guertin, Daniel Gioeli
University of Virginia, Charlottesville, VA, United States., University of Virginia, Charlottesvillle, VA, United States., University of Virginia, Charlottesville, Va, United States., University of Virginia Health System, Charlottesville, Virginia, United States., University of Connecticut Health Center, Farmington, Connecticut, United States., The University of Texas MD Anderson Cancer Center, Houston, TX, United States.