DHX15 promotes prostate cancer progression by stimulating Siah2-mediated ubiquitination of androgen receptor


Androgen receptor (AR) activation is critical for prostate cancer (PCa) development and progression, including castration resistance. The nuclear export signal of AR (NESAR) has an important role in AR intracellular trafficking and proteasome-dependent degradation. Here, we identified the RNA helicase DHX15 as a novel AR co-activator using a yeast mutagenesis screen and revealed that DHX15 regulates AR activity by modulating E3 ligase Siah2-mediated AR ubiquitination independent of its ATPase activity. DHX15 and Siah2 form a complex with AR, through NESAR. DHX15 stabilized Siah2 and enhanced its E3 ubiquitin-ligase activity, resulting in AR activation. Importantly, DHX15 was upregulated in PCa specimens and its expression was correlated with Gleason scores and prostate-specific antigen recurrence. Furthermore, DHX15 immunostaining correlated with Siah2. Finally, DHX15 knockdown inhibited the growth of C4-2 prostate tumor xenografts in mice. Collectively, our data argue that DHX15 enhances AR transcriptional activity and contributes to PCa progression through Siah2.

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We thank Aiyuan Zhang for technical support, Richard Gaber (Northwestern University) for advice on yeast screen, the PCBN for TMA with PCa specimens, Megan Lambert, Krystal Roskov and Robin Frederick for animal husbandry, and members of the Wang Lab for discussion. This work was supported in part by NIH R01 CA186780 (ZW), NIH R01 CA108675 (ZW), ACS #PF-05-229-01-CSM (MMN), the Department of Defense Prostate Cancer Research Program Award No W81XWH-14-2-0182, W81XWH-14-2-0183, W81XWH-14-2-0185, W81XWH-14-2-0186, and W81XWH-15-2-0062 PCBN, National Nature Science Foundation of China #81402091 (YJ), and National Natural Science Foundation of China Key Project 81130046 (JZ) and 2013GXNSFEA053004 (JZ). This work was also supported by a post-doctoral fellowship from the Urology Care Foundation of the American Urological Association (DW), the Mellam Family Fellowship (DW and KZM), the Tippens Scholarship (LEP) and NIH R50 CA211242-01 (LEP). In addition, this research was supported by the UPCI Animal Facility, Vector Core and Tissue and Research Pathology Services (TARPS) funded through NCI CCSG P30CA047904.

Author contributions

Yifeng Jing conceived and performed the majority of experiments and wrote manuscript. Minh M Nguyen performed the yeast screening. Dan Wang constructed the plasmids of flag-DHX15 and myc-DHX15, performed radioactive ligand-binding assay and ChIP and assisted with technical details and experimental design. Laura E Pascal performed animal experiments and analysis of the animal data, and helped with manuscript. Wenhuan Guo constructed the truncated Siah2 plasmids, performed parts of BrdU assay and several extractions of proteins and RNAs. Yadong Xu generated data for Supplementary Figures S1 and S3. Junkui Ai constructed the plasmid of Flag-AR and C4-2-AR, assisted with technical details. Fang-ming Deng performed IHC. Khalid Masoodi constructed and standardized the primers of DHX15. Xinpei Yu performed some of the ubiquitination IP assays. Shujie Xia, Jian Zhang, Joel B Nelson conceived study and helped with manuscript. Zhou Wang conceived and directed study, and helped with manuscript.

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Correspondence to S Xia or Z Wang.

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Jing, Y., Nguyen, M., Wang, D. et al. DHX15 promotes prostate cancer progression by stimulating Siah2-mediated ubiquitination of androgen receptor. Oncogene 37, 638–650 (2018). https://doi.org/10.1038/onc.2017.371

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