ERG induces androgen receptor-mediated regulation of SOX9 in prostate cancer
Changmeng Cai, … , Steven P. Balk, Xin Yuan
Changmeng Cai, … , Steven P. Balk, Xin Yuan
Published February 15, 2013
Citation Information: J Clin Invest. 2013;123(3):1109-1122. https://doi.org/10.1172/JCI66666.
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Research Article Oncology

ERG induces androgen receptor-mediated regulation of SOX9 in prostate cancer

Abstract

Fusion of the androgen receptor-regulated (AR-regulated) TMPRSS2 gene with ERG in prostate cancer (PCa) causes androgen-stimulated overexpression of ERG, an ETS transcription factor, but critical downstream effectors of ERG-mediating PCa development remain to be established. Expression of the SOX9 transcription factor correlated with TMPRSS2:ERG fusion in 3 independent PCa cohorts, and ERG-dependent expression of SOX9 was confirmed by RNAi in the fusion-positive VCaP cell line. SOX9 has been shown to mediate ductal morphogenesis in fetal prostate and maintain stem/progenitor cell pools in multiple adult tissues, and has also been linked to PCa and other cancers. SOX9 overexpression resulted in neoplasia in murine prostate and stimulated tumor invasion, similarly to ERG. Moreover, SOX9 depletion in VCaP cells markedly impaired invasion and growth in vitro and in vivo, establishing SOX9 as a critical downstream effector of ERG. Finally, we found that ERG regulated SOX9 indirectly by opening a cryptic AR-regulated enhancer in the SOX9 gene. Together, these results demonstrate that ERG redirects AR to a set of genes including SOX9 that are not normally androgen stimulated, and identify SOX9 as a critical downstream effector of ERG in TMPRSS2:ERG fusion–positive PCa.

Authors

Changmeng Cai, Hongyun Wang, Housheng Hansen He, Sen Chen, Lingfeng He, Fen Ma, Lorelei Mucci, Qianben Wang, Christopher Fiore, Adam G. Sowalsky, Massimo Loda, X. Shirley Liu, Myles Brown, Steven P. Balk, Xin Yuan

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Figure 5

AR directly regulates SOX9 in VCaP cells through activation of an enhancer in the SOX9 gene.

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AR directly regulates SOX9 in VCaP cells through activation of an enhanc...
(A) VCaP cells were treated with or without DHT for 4, 8, or 24 hours and SOX9 mRNA was measured by qRT-PCR. (B) VCaP cells were treated with or without DHT for 4, 8, or 24 hours and SOX9, PSA, or β-actin was immunoblotted. (C) VCaP cells were treated with cycloheximide (10 ng/mL) and DHT or vehicle (ethanol), and SOX9 mRNA was then measured by qRT-PCR after 0–8 hours. (D) Distinct AR binding sites identified by ChIP-seq and ChIP-chip in LNCaP cells (S1 site) and VCaP cells (S2). A peak at S1 in VCaP could also be detected by decreasing the threshold of peak analysis, suggesting that AR binds weakly to this site in VCaP cells. (E) VCaP cells were treated with or without DHT and with 10 μM Bic or vehicle control (DMSO) for 4 hours followed by AR ChIP and qPCR for the S2 site. (F) VCaP cells were treated with or without DHT for 4 hours followed by AR, FOXA1, active RNA polymerase II (phospho-Ser5 on CTD), p300, or GATA2 ChIP and qPCR for the S1 site, S2 site, or PSA enhancer ARE (PSA-ARE3). (G) LNCaP cells were treated with or without DHT for 4 hours followed by AR, FOXA1, p300, or GATA2 ChIP and qPCR for the S1 site, S2 site, or PSA enhancer. The DHT concentration used in experiments was 10 nM. Data in bar graphs represent means ± SD of at least 3 biological repeats.