The catalytic subunit of DNA-PK regulates transcription and splicing of AR in advanced prostate cancer
Beth Adamson, … , Johann S. de Bono, Luke Gaughan
Beth Adamson, … , Johann S. de Bono, Luke Gaughan
Published September 26, 2023
Citation Information: J Clin Invest. 2023;133(22):e169200. https://doi.org/10.1172/JCI169200.
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Research Article Endocrinology Oncology Article has an altmetric score of 8

The catalytic subunit of DNA-PK regulates transcription and splicing of AR in advanced prostate cancer

Abstract

Aberrant androgen receptor (AR) signaling drives prostate cancer (PC), and it is a key therapeutic target. Although initially effective, the generation of alternatively spliced AR variants (AR-Vs) compromises efficacy of treatments. In contrast to full-length AR (AR-FL), AR-Vs constitutively activate androgenic signaling and are refractory to the current repertoire of AR-targeting therapies, which together drive disease progression. There is an unmet clinical need, therefore, to develop more durable PC therapies that can attenuate AR-V function. Exploiting the requirement of coregulatory proteins for AR-V function has the capacity to furnish tractable routes for attenuating persistent oncogenic AR signaling in advanced PC. DNA-PKcs regulates AR-FL transcriptional activity and is upregulated in both early and advanced PC. We hypothesized that DNA-PKcs is critical for AR-V function. Using a proximity biotinylation approach, we demonstrated that the DNA-PK holoenzyme is part of the AR-V7 interactome and is a key regulator of AR-V–mediated transcription and cell growth in models of advanced PC. Crucially, we provide evidence that DNA-PKcs controls global splicing and, via RBMX, regulates the maturation of AR-V and AR-FL transcripts. Ultimately, our data indicate that targeting DNA-PKcs attenuates AR-V signaling and provide evidence that DNA-PKcs blockade is an effective therapeutic option in advanced AR-V–positive patients with PC.

Authors

Beth Adamson, Nicholas Brittain, Laura Walker, Ruaridh Duncan, Sara Luzzi, Pasquale Rescigno, Graham Smith, Suzanne McGill, Richard J.S. Burchmore, Elaine Willmore, Ian Hickson, Craig N. Robson, Denisa Bogdan, Juan M. Jimenez-Vacas, Alec Paschalis, Jonathan Welti, Wei Yuan, Stuart R. McCracken, Rakesh Heer, Adam Sharp, Johann S. de Bono, Luke Gaughan

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Figure 5

DNA-PKcs regulates a splicing-associated gene signature.

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DNA-PKcs regulates a splicing-associated gene signature. (A) RNA-Seq dat...
(A) RNA-Seq data derived from CWR22Rv1-AR-EK cells depleted of DNA-PKcs was analyzed for differential splicing activity using SUPPA2 inbuilt statistical test (ref. 65). Events that passed a P value cut off of <0.05 were plotted in the pie chart. (B) Diagrammatic representation and quantification of the statistically significant splicing alterations detected in response to DNA-PKcs depletion, as determined using SUPPA2 inbuilt statistical test (ref 65). (C) Upregulation of AR-V7 in response to darolutamide was validated by Western blotting using an anti-AR-V7 antibody. (D) Differentially expressed splicing-associated genes from DNA-PKcs depleted and NU5455-treated cells were analyzed by GSEA using a darolutamide-responsive gene set (Baumgart et al., ref. 54) to identify splicing factor expression correlating with AR-V7 synthesis. (E) 34 splicing-associated genes were found to be upregulated in response to darolutamide and are shown in the heatmap.