MYBL2 disrupts the Hippo-YAP pathway and confers castration resistance and metastatic potential in prostate cancer.

Rationale: Resistance to androgen-deprivation therapy (ADT) associated with metastatic progression remains a challenging clinical task in prostate cancer (PCa) treatment. Current targeted therapies for castration-resistant prostate cancer (CRPC) are not durable. The exact molecular mechanisms mediating resistance to castration therapy that lead to CRPC progression remain obscure. Methods: The expression of MYB proto-oncogene like 2 (MYBL2) was evaluated in PCa samples. The effect of MYBL2 on the response to ADT was determined by in vitro and in vivo experiments. The survival of patients with PCa was analyzed using clinical specimens (n = 132) and data from The Cancer Genome Atlas (n = 450). The mechanistic model of MYBL2 in regulating gene expression was further detected by subcellular fractionation, western blotting, quantitative real-time PCR, chromatin immunoprecipitation, and luciferase reporter assays. Results: MYBL2 expression was significantly upregulated in CRPC tissues and cell lines. Overexpression of MYBL2 could facilitate castration-resistant growth and metastatic capacity in androgen-dependent PCa cells by promoting YAP1 transcriptional activity via modulating the activity of the Rho GTPases RhoA and LATS1 kinase. Importantly, targeting MYBL2, or treatment with either the YAP/TAZ inhibitor Verteporfin or the RhoA inhibitor Simvastatin, reversed the resistance to ADT and blocked bone metastasis in CRPC cells. Finally, high MYBL2 levels were positively associated with TNM stage, total PSA level, and Gleason score and predicted a higher risk of metastatic relapse and poor prognosis in patients with PCa. Conclusions: Our results reveal a novel molecular mechanism conferring resistance to ADT and provide a strong rationale for potential therapeutic strategies against CRPC.

Li Q ，Wang M ，Hu Y ，Zhao E ，Li J ，Ren L ，Wang M ，Xu Y ，Liang Q ，Zhang D ，Lai Y ，Liu S ，Peng X ，Zhu C ，Ye L ... -  《Theranostics》

miR-30a inhibits androgen-independent growth of prostate cancer via targeting MYBL2, FOXD1, and SOX4.

Castrate-resistant prostate cancer (CRPC) is an aggressive and lethal disease. The pathogenesis of CRPC is not fully understood and novel therapeutic targets need to be identified to improve the patients' prognosis. MicroRNA-30a (miR-30a) has been demonstrated to be a tumor suppressor in many types of solid malignancies. However, its role in androgen-independent (AI) growth of prostate cancer (PCa) received limited attention as yet. The clinical association of miR-30a and its potential targets with AI growth was characterized by bioinformatics analyses. Regulation of cell proliferation and colony formation rates by miR-30a were tested using PCa cell models. Xenograft models were used to measure the regulation of prostate tumor growth by miR-30a. The real-time quantitative polymerase chain reaction was used to validate whether miR-30a and its targets regulate cell cycle control genes and androgen receptor (AR)-dependent transcription. Bioinformatics tools, Western blot, and luciferase reporter assays were utilized to identify miR-30a targets. Bioinformatic analysis showed that low expression of miR-30a is associated with castration resistance of PCa patients and poor outcomes. Transfection of miR-30a mimics inhibited the AI growth of PCa cells in vitro and in vivo. Upregulation of miR-30a in 22RV1 cells altered the expression of cell cycle control genes and AR-mediated transcription, while downregulation of miR-30a in LNCaP cells had the opposite effects to AR-mediated transcription. MYBL2, FOXD1, and SOX4 were identified as miR-30a targets. Downregulation of MYBL2, FOXD1, and SOX4 affected the expression of cell cycle control genes and AR-mediated transcription and suppressed the AI growth of 22RV1 cells. Our results suggest that miR-30a inhibits AI growth of PCa by targeting MYBL2, FOXD1, and SOX4. They provide novel insights into developing new treatment strategies for CRPC.

Li X ，Jiao M ，Hu J ，Qi M ，Zhang J ，Zhao M ，Liu H ，Xiong X ，Dong X ，Han B ... -  《-》

BRD4 Regulates Metastatic Potential of Castration-Resistant Prostate Cancer through AHNAK.

The inevitable progression of advanced prostate cancer to castration resistance, and ultimately to lethal metastatic disease, depends on primary or acquired resistance to conventional androgen deprivation therapy (ADT) and accumulated resistance strategies to evade androgen receptor (AR) suppression. In prostate cancer cells, AR adaptations that arise in response to ADT are not singular, but diverse, and include gene amplification, mutation, and even complete loss of receptor expression. Collectively, each of these AR adaptations contributes to a complex, heterogeneous, ADT-resistant tumor. Here, we examined prostate cancer cell lines that model common castration-resistant prostate cancer (CRPC) subtypes, each with different AR composition, and focused on novel regulators of tumor progression, the Bromodomain and Extraterminal (BET) family of proteins. We found that BRD4 regulates cell migration across all models of CRPC, regardless of aggressiveness and AR status, whereas BRD2 and BRD3 only regulate migration and invasion in less aggressive models that retain AR expression or signaling. BRD4, a coregulator of gene transcription, controls migration and invasion through transcription of AHNAK, a large scaffolding protein linked to promotion of metastasis in a diverse set of cancers. Furthermore, treatment of CRPC cell lines with low doses of MZ1, a small-molecule, BRD4-selective degrader, inhibits metastatic potential. Overall, these results reveal a novel BRD4-AHNAK pathway that may be targetable to treat metastatic CRPC (mCRPC). IMPLICATIONS: BRD4 functions as the dominant regulator of CRPC cell migration and invasion through direct transcriptional regulation of AHNAK, which together offer a novel targetable pathway to treat metastatic CRPC.Visual Overview: http://mcr.aacrjournals.org/content/molcanres/17/8/1627/F1.large.jpg.

Shafran JS ，Andrieu GP ，Györffy B ，Denis GV ... -  《-》

miR-302/367/LATS2/YAP pathway is essential for prostate tumor-propagating cells and promotes the development of castration resistance.

Guo Y ，Cui J ，Ji Z ，Cheng C ，Zhang K ，Zhang C ，Chu M ，Zhao Q ，Yu Z ，Zhang Y ，Fang YX ，Gao WQ ，Zhu HH ... -  《-》

RGS2 is prognostic for development of castration resistance and cancer-specific survival in castration-resistant prostate cancer.

Regulator of G-protein signaling 2 (RGS2) is a multifaceted protein with a prognostic value in hormone-naïve prostate cancer (PC). It has previously been associated with the development of castration resistance. However, RGS2 expression in clinical specimens of castration-resistant prostate cancer (CRPC) and its clinical relevance has not been explored. In the present study, RGS2 was assessed in CRPC and in relation to the development of castration resistance. In the present study, RGS2 expression was evaluated with immunohistochemistry in patient materials of hormone-naïve and castration-resistant primary tumors, also in matched specimens before and after 3 months of androgen deprivation therapy (ADT). Cox regression and Kaplan-Meier curves were used to evaluate the clinical significance of RGS2 expression. RGS2 expression in association to castration-resistant growth was assessed experimentally in an orthotopic xenograft mouse model of CRPC. In vitro, hormone depletion of LNCaP and enzalutamide treatment of LNCaP, 22Rv1, and VCaP was performed to evaluate the association between RGS2 and the androgen receptor (AR). Stable RGS2 knockdown was used to evaluate the impact of RGS2 in association to PC cell growth under hormone-reduced conditions. Gene and protein expression were evaluated with quantitative polymerase chain reaction and Western blot analysis, respectively. RGS2 expression is increased in CRPC and enriched under ADT. Furthermore, a high RGS2 level is prognostic for poor cancer-specific survival for CRPC patients and significantly reduced failure-free survival (FFS) after an initiated ADT. Additionally, the prognostic value of RGS2 outperforms prostate-specific antigen (PSA) in terms of FFS. The present study furthermore suggests that RGS2 expression is reflective of AR activity. Moreover, low RGS2-expressing cells display hampered growth under hormone-reduced conditions, in line with the poor prognosis associated with high RGS2 expression. High levels of RGS2 are associated with aggressive forms of castration-resistant PC. The results demonstrate that a high level of RGS2 is associated with poor prognosis in association with castration-resistant PC growth. RGS2 alone, or in association with PSA, has the potential to identify patients that require additional treatment at an early stage during ADT.

Linder A ，Larsson K ，Welén K ，Damber JE ... -  《-》