Androgen receptor splice variants drive castration-resistant prostate cancer metastasis by activating distinct transcriptional programs
Dong Han, … , Xiaohong Li, Changmeng Cai
Dong Han, … , Xiaohong Li, Changmeng Cai
Published April 30, 2024
Citation Information: J Clin Invest. 2024;134(11):e168649. https://doi.org/10.1172/JCI168649.
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Research Article Oncology

Androgen receptor splice variants drive castration-resistant prostate cancer metastasis by activating distinct transcriptional programs

Abstract

One critical mechanism through which prostate cancer (PCa) adapts to treatments targeting androgen receptor (AR) signaling is the emergence of ligand-binding domain–truncated and constitutively active AR splice variants, particularly AR-V7. While AR-V7 has been intensively studied, its ability to activate distinct biological functions compared with the full-length AR (AR-FL), and its role in regulating the metastatic progression of castration-resistant PCa (CRPC), remain unclear. Our study found that, under castrated conditions, AR-V7 strongly induced osteoblastic bone lesions, a response not observed with AR-FL overexpression. Through combined ChIP-seq, ATAC-seq, and RNA-seq analyses, we demonstrated that AR-V7 uniquely accesses the androgen-responsive elements in compact chromatin regions, activating a distinct transcription program. This program was highly enriched for genes involved in epithelial-mesenchymal transition and metastasis. Notably, we discovered that SOX9, a critical metastasis driver gene, was a direct target and downstream effector of AR-V7. Its protein expression was dramatically upregulated in AR-V7–induced bone lesions. Moreover, we found that Ser81 phosphorylation enhanced AR-V7’s pro-metastasis function by selectively altering its specific transcription program. Blocking this phosphorylation with CDK9 inhibitors impaired the AR-V7–mediated metastasis program. Overall, our study has provided molecular insights into the role of AR splice variants in driving the metastatic progression of CRPC.

Authors

Dong Han, Maryam Labaf, Yawei Zhao, Jude Owiredu, Songqi Zhang, Krishna Patel, Kavita Venkataramani, Jocelyn S. Steinfeld, Wanting Han, Muqing Li, Mingyu Liu, Zifeng Wang, Anna Besschetnova, Susan Patalano, Michaela J. Mulhearn, Jill A. Macoska, Xin Yuan, Steven P. Balk, Peter S. Nelson, Stephen R. Plymate, Shuai Gao, Kellee R. Siegfried, Ruihua Liu, Mary M. Stangis, Gabrielle Foxa, Piotr J. Czernik, Bart O. Williams, Kourosh Zarringhalam, Xiaohong Li, Changmeng Cai

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Figure 3

AR-V7–activated transcription program is enriched for EMT/metastasis functions.

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AR-V7–activated transcription program is enriched for EMT/metastasis fun...
(A) Heatmap view of identified AR-V7–activated EMT genes (37-gene signature). (B) GSEA NES of 2 public bone metastasis signatures (VICENT_BONE_MET, 20-gene; CAI_BONE_MET, 44-gene) in each model were plotted (red, activated pathways; blue, repressed pathways). Statistical analyses were conducted using unpaired, nonparametric 2-sample Wilcoxon’s test for box-and-whisker plots, with Bonferroni’s correction for multiple comparisons. (C) Fold-change of AR-V7–activated EMT genes (37-gene signature) in 22RV1, 35CR, LN-tet-ARV7, and LN-tet-ARFL cells. P values by Wilcoxon’s test are shown above the horizontal bars. (D) qRT-PCR for a panel of AR-V7–regulated genes in LN-tet-ARV7 cells treated with or without 0.25 μg/mL doxycycline. (E and F) qRT-PCR for a panel of AR-V7–regulated genes in 22Rv1 (E) or 35CR (F) cells transfected with siNTC or siARV7. (G) qRT-PCR for SOX9 and COL25A1 in LN-cu-ARv567es cells treated with 10 nM DHT for 24 hours or 30 μg/mL cumate for 48 hours. (H) qRT-PCR for a panel of AR-V7–regulated genes in parental LNCaP cells treated with or without 10 nM DHT for 24 hours. All the cell lines were hormone depleted prior to the experiments. For the bar graphs, an unpaired, 2-sided Student’s t test was used to determine statistical significance. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. Data are represented as mean ± SEM.