Activation of GPR56, a novel adhesion GPCR, is necessary for nuclear androgen receptor signaling in prostate cells

AbstractThe androgen receptor (AR) is activated in patients with castration resistant prostate cancer (CRPC) despite low circulating levels of androgen, suggesting that intracellular signaling pathways and non-androgenic factors may contribute to AR activation. Many G-protein coupled receptors (GPCR) and their ligands are also activated in these cells indicating a role for these in CRPC. Although a cross talk has been suggested between the two pathways, yet, the identity of GPCRs which may play a role in androgen signaling, is not established yet. We demonstrate that adhesion GPCR 205, also known as GPR56, can be activated by androgens to stimulate the Rho signaling pathway, a pathway that plays an important role in prostate tumor cell metastasis. Testosterone stimulation of GPR56 also activates the cAMP/ Protein kinase A (PKA) pathway, that is necessary for AR signaling. Knocking down the expression of GPR56 using siRNA, disrupts nuclear translocation of AR and transcription of prototypic AR target genes such as PSA. GPR56 expression is higher in all prostate tumor samples tested and cells expressing GPR56 exhibit increased proliferation. These findings provide new insights about androgen signaling and identify GPR56 as a possible therapeutic target in advanced prostate cancer patients.

Download Full-text

Isoform specific activities of androgen receptor and its splice variants in prostate cancer cells

Endocrinology ◽

10.1210/endocr/bqaa227 ◽

2020 ◽

Author(s):

Harika Nagandla ◽

Matthew J Robertson ◽

Vasanta Putluri ◽

Nagireddy Putluri ◽

Cristian Coarfa ◽

...

Keyword(s):

Prostate Cancer ◽

Androgen Receptor ◽

Target Gene ◽

Target Genes ◽

Splice Variants ◽

Clinical Samples ◽

Castration Resistant Prostate Cancer ◽

Castration Resistant ◽

Specific Activities ◽

Lncap Prostate Cancer Cell

Abstract Androgen receptor (AR) signaling continues to drive castration resistant prostate cancer (CRPC) in spite of androgen deprivation therapy (ADT). Constitutively active shorter variants of AR, lacking the ligand binding domain, are frequently expressed in CRPC and have emerged as a potential mechanism for prostate cancer to escape ADT. ARv7 and AR v567es are two of the most commonly detected variants of AR in clinical samples of advanced, metastatic prostate cancer. It is not clear if variants of AR merely act as weaker substitutes for AR or can mediate unique isoform specific activities different from AR. In this study, we employed LNCaP prostate cancer cell lines with inducible expression of ARv7 or AR v567es to delineate similarities and differences in transcriptomics, metabolomics and lipidomics resulting from the activation of AR, ARv7 or AR v567es. While the majority of target genes were similarly regulated by the action of all three isoforms, we found a clear difference in transcriptomic activities of AR versus the variants, and a few differences between ARv7 and AR v567es. Some of the target gene regulation by AR isoforms was similar in the VCaP background as well. Differences in downstream activities of AR isoforms were also evident from comparison of the metabolome and lipidome in an LNCaP model. Overall our study implies that shorter variants of AR are capable of mediating unique downstream activities different from AR and some of these are isoform specific.

Download Full-text

Huaier Extract Inhibits Prostate Cancer Growth via Targeting AR/AR-V7 Pathway

Frontiers in Oncology ◽

10.3389/fonc.2021.615568 ◽

2021 ◽

Vol 11 ◽

Author(s):

Zhengfang Liu ◽

Cheng Liu ◽

Keqiang Yan ◽

Jikai Liu ◽

Zhiqing Fang ◽

...

Keyword(s):

Prostate Cancer ◽

Androgen Receptor ◽

Nuclear Translocation ◽

Mrna Levels ◽

Castration Resistant Prostate Cancer ◽

Castration Resistant ◽

Specific Protease ◽

Hormone Sensitive

The androgen receptor (AR) plays a pivotal role in prostatic carcinogenesis, and it also affects the transition from hormone sensitive prostate cancer (HSPC) to castration-resistant prostate cancer (CRPC). Particularly, the persistent activation of the androgen receptor and the appearance of androgen receptor splicing variant 7 (AR-V7), could partly explain the failure of androgen deprivation therapy (ADT). In the present study, we reported that huaier extract, derived from officinal fungi, has potent antiproliferative effects in both HSPC and CRPC cells. Mechanistically, huaier extract downregulated both full length AR (AR-FL) and AR-V7 mRNA levels via targeting the SET and MYND domain-containing protein 3 (SMYD3) signaling pathway. Huaier extract also enhanced proteasome-mediated protein degradation of AR-FL and AR-V7 by downregulating proteasome-associated deubiquitinase ubiquitin-specific protease 14 (USP14). Furthermore, huaier extract inhibited AR-FL/AR-V7 transcriptional activity and their nuclear translocation. More importantly, our data demonstrated that huaier extract could re-sensitize enzalutamide-resistant prostate cancer cells to enzalutamide treatment in vitro and in vivo models. Our work revealed that huaier extract could be effective for treatment of prostate cancer either as monotherapy or in combination with enzalutamide.

Download Full-text

ODM-204: A novel dual inhibitor of CYP17A1 and androgen receptor for the treatment of castration-resistant prostate cancer—Preclinical data.

Journal of Clinical Oncology ◽

10.1200/jco.2015.33.7_suppl.221 ◽

2015 ◽

Vol 33 (7_suppl) ◽

pp. 221-221

Author(s):

Riikka Oksala ◽

Anu Moilanen ◽

Reetta Riikonen ◽

Petteri Rummakko ◽

Riikka Huhtaniemi ◽

...

Keyword(s):

Prostate Cancer ◽

Androgen Receptor ◽

Nuclear Translocation ◽

Leuprolide Acetate ◽

Male Rats ◽

Castration Resistant Prostate Cancer ◽

Dual Inhibitor ◽

Castration Resistant

221 Background: Castration-resistant prostate cancer (CRPC) is characterized by high androgen receptor (AR) expression and persistent activation of AR signaling axis by residual tissue/tumor androgens. Targeting AR and androgen biosynthesis together may be more effective than either alone. ODM-204 is a novel, non-steroidal dual inhibitor of CYP17A1 and AR, which has shown promising results in preclinical studies. Methods: The binding affinity of ODM-204 to wild type AR was determined in rat prostate cytosolic lysates. The potency and functional activity of ODM-204 to human AR were demonstrated in cells stably transfected with the full-length AR and androgen-responsive reporter gene constructs. In addition, assays for AR nuclear translocation and the transactivation of human AR mutants T877A, W741L, and F876L were conducted. The effects of ODM-204 on the growth of androgen-dependent VCaP and LNCaP cells in vitro and subcutaneously grafted VCaP cells in vivo with the oral dose of 50 mg/kg/day were studied. The inhibition of CYP17A1 by ODM-204 was studied in vitro by using human and rat testicular microsomes and a human adrenal cortex cell line, and in vivo in male rats coadministered with luteinizing hormone releasing hormone agonist leuprolide acetate to mimic clinical situation. Results: ODM-204 is a potent inhibitor of both AR and CYP17A1. It binds to AR with a high affinity (Ki=47 nM) and selectivity and has a high potency towards CYP17A1 (IC50=22 nM). In addition, ODM-204 inhibited testosterone-mediated nuclear translocation of AR and the mutant ARs (IC50 values for AR(T877A), AR(W741L), and AR(F876L) were 95, 277, and 6 nM, respectively), and suppressed androgen-induced cell proliferation of LNCaP (IC50=170 nM) and VCaP (IC50=280 nM) cells. In a VCaP xenograft model, ODM-204 showed significant antitumor activity (tumor growth inhibition=66%). In rats, inhibitory effects of leuprolide acetate on testosterone production and androgen-sensitive organ weights were potentiated by ODM-204. Conclusions: ODM-204 is a promising new dual CYP17A1 and AR inhibitor for the treatment of CRPC. Clinical trials in patients with mCRPC will be started in early 2015.

Download Full-text

Androgen Receptor Splice Variant 7 Drives the Growth of Castration Resistant Prostate Cancer without Being Involved in the Efficacy of Taxane Chemotherapy

Journal of Clinical Medicine ◽

10.3390/jcm7110444 ◽

2018 ◽

Vol 7 (11) ◽

pp. 444 ◽

Cited By ~ 8

Author(s):

Yasuomi Shimizu ◽

Satoshi Tamada ◽

Minoru Kato ◽

Yukiyoshi Hirayama ◽

Yuji Takeyama ◽

...

Keyword(s):

Prostate Cancer ◽

Androgen Receptor ◽

Splice Variant ◽

Target Genes ◽

Inhibitory Effect ◽

Cross Resistance ◽

Castration Resistant Prostate Cancer ◽

Amino Terminal ◽

Castration Resistant ◽

Androgen Receptor Splice Variant

Expression of androgen receptor (AR) splice variant 7 (AR-V7) has been identified as the mechanism associated with the development of castration-resistant prostate cancer (CRPC). However, a potential link between AR-V7 expression and resistance to taxanes, such as docetaxel or cabazitaxel, has not been unequivocally demonstrated. To address this, we used LNCaP95-DR cells, which express AR-V7 and exhibit resistance to enzalutamide and docetaxel. Interestingly, LNCaP95-DR cells showed cross-resistance to cabazitaxel. Furthermore, these cells had increased levels of P-glycoprotein (P-gp) and their sensitivity to both docetaxel and cabazitaxel was restored through treatment with tariquidar, a P-gp antagonist. Results generated demonstrated that P-gp mediated cross-resistance between docetaxel and cabazitaxel. Although the LNCaP95-DR cells had increased expression of AR-V7 and its target genes (UBE2C, CDC20), the knockdown of AR-V7 did not restore sensitivity to docetaxel or cabazitaxel. However, despite resistance to docetaxel and carbazitaxel, EPI-002, an antagonist of the AR amino-terminal domain (NTD), had an inhibitory effect on the proliferation of LNCaP95-DR cells, which was similar to that achieved with the parental LNCaP95 cells. On the other hand, enzalutamide had no effect on the proliferation of either cell line. In conclusion, our results suggested that EPI-002 may be an option for the treatment of AR-V7-driven CRPC, which is resistant to taxanes.

Download Full-text

Peroxisome Proliferator-Activated Receptor γ Coactivator-1α Interacts with the Androgen Receptor (AR) and Promotes Prostate Cancer Cell Growth by Activating the AR

Molecular Endocrinology ◽

10.1210/me.2009-0302 ◽

2010 ◽

Vol 24 (1) ◽

pp. 114-127 ◽

Cited By ~ 45

Author(s):

Masaki Shiota ◽

Akira Yokomizo ◽

Yasuhiro Tada ◽

Junichi Inokuchi ◽

Katsunori Tatsugami ◽

...

Keyword(s):

Prostate Cancer ◽

Androgen Receptor ◽

Cell Growth ◽

Target Genes ◽

Specific Antigen ◽

Peroxisome Proliferator ◽

Castration Resistant Prostate Cancer ◽

Promoter Regions ◽

Peroxisome Proliferator Activated Receptor ◽

Castration Resistant

Abstract There are currently few successful therapies for castration-resistant prostate cancer (CRPC). CRPC is thought to result from augmented activation of the androgen/androgen receptor (AR) signaling pathway, which could be enhanced by AR cofactors. In this study, peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) was found to be an AR cofactor. PGC-1α interacted with the N-terminal domain of AR, was involved in the N- and C-terminal interaction of AR, and enhanced the DNA-binding ability of AR to androgen-responsive elements in the prostate-specific antigen enhancer and promoter regions to increase the transcription of AR target genes. Silencing of PGC-1α suppressed cell growth of AR-expressing prostate cancer (PCa) cells by inducing cell-cycle arrest at the G1 phase, similar to inhibition of androgen/AR signaling. Furthermore, PGC-1α knock-down also suppressed cell growth in the castration-resistant LNCaP-derivatives. These findings indicate that PGC-1α is involved in the proliferation of AR-expressing PCa cells by acting as an AR coactivator. Modulation of PGC-1α expression or function may offer a useful strategy for developing novel therapeutics for PCa, including CRPC, which depends on AR signaling by overexpressing AR and its coactivators.

Download Full-text

Human heterochromatin protein 1 isoform HP1β enhances androgen receptor activity and is implicated in prostate cancer growth

Endocrine Related Cancer ◽

10.1677/erc-09-0321 ◽

2010 ◽

Vol 17 (2) ◽

pp. 455-467 ◽

Cited By ~ 14

Author(s):

M Shiota ◽

Y Song ◽

A Yokomizo ◽

Y Tada ◽

K Kuroiwa ◽

...

Keyword(s):

Prostate Cancer ◽

Androgen Receptor ◽

Target Genes ◽

Specific Antigen ◽

Castration Resistant Prostate Cancer ◽

Heterochromatin Protein 1 ◽

Promoter Regions ◽

Heterochromatin Protein ◽

Castration Resistant ◽

Androgen Receptor Activity

There are currently few successful therapies for castration-resistant prostate cancer (CRPC). CRPC is thought to result from augmented activation of the androgen/androgen receptor (AR) signaling pathway, which could be enhanced by AR cofactors. In this study, heterochromatin protein 1β (HP1β), but not HP1α or HP1γ was found to be an AR cofactor. HP1β interacted with the AR, and enhanced the DNA-binding ability of AR to androgen-responsive element in the prostate-specific antigen enhancer and promoter regions, and to increase the transcription of AR target genes. In prostate cancer (PCa) tissues, HP1β expressions correlated with Gleason score and tri-methylation levels of histone H3 lysine 9. Silencing of HP1β suppressed the growth of AR-expressing PCa cells by inducing cell-cycle arrest at the G1 phase, similar to inhibition of androgen/AR signaling. Furthermore, HP1β was overexpressed in castration-resistant LNCaP derivative CxR cells, and HP1β knockdown also suppressed the cell growth in CxR cells. These findings indicate that HP1β is involved in the proliferation of AR-expressing PCa cells and progression to CRPC as an AR coactivator. Modulation of HP1β expression or function might be a useful strategy for developing novel therapeutics for PCa, even in CRPC.

Download Full-text

3β-Hydroxysteroid Dehydrogenase Is a Possible Pharmacological Target in the Treatment of Castration-Resistant Prostate Cancer

Endocrinology ◽

10.1210/en.2010-0138 ◽

2010 ◽

Vol 151 (8) ◽

pp. 3514-3520 ◽

Cited By ~ 50

Author(s):

Kristen Evaul ◽

Rui Li ◽

Mahboubeh Papari-Zareei ◽

Richard J. Auchus ◽

Nima Sharifi

Keyword(s):

Prostate Cancer ◽

Cell Proliferation ◽

Androgen Receptor ◽

Nuclear Translocation ◽

De Novo ◽

Hydroxysteroid Dehydrogenase ◽

Adrenal Steroids ◽

Castration Resistant Prostate Cancer ◽

Castration Resistant ◽

Pharmacological Target

Prostate cancer usually responds to androgen deprivation therapy, although the response in metastatic disease is almost always transient and tumors eventually progress as castration-resistant prostate cancer (CRPC). CRPC continues to be driven by testosterone or dihydrotestosterone from intratumoral metabolism of 19-carbon adrenal steroids from circulation, and/or de novo intratumoral steroidogenesis. Both mechanisms require 3β-hydroxysteroid dehydrogenase (3βHSD) metabolism of Δ5-steroids, including dehydroepiandrosterone (DHEA) and Δ5-androstenediol (A5diol), to testosterone. In contrast, reports that DHEA and A5diol directly activate the androgen receptor (AR) suggest that 3βHSD metabolism is not required and that 3βHSD inhibitors would be ineffective in the treatment of CRPC. We hypothesized that activation of AR in prostate cancer by DHEA and A5diol requires their conversion via 3βHSD to androstenedione and testosterone, respectively. Here, we show that DHEA and A5diol induce AR chromatin occupancy and AR-regulated genes. Furthermore, we show that Δ5-androgens undergo 3β-dehydrogenation in prostate cancer and that induction of AR nuclear translocation, AR chromatin occupancy, transcription of PSA, TMPRSS2, and FKBP5, as well as cell proliferation by DHEA and A5diol, are all blocked by inhibitors of 3βHSD. These findings demonstrate that DHEA and A5diol must be metabolized by 3βHSD to activate AR in these models of CRPC. Furthermore, this work suggests that 3βHSD may be exploited as a pharmacologic target in the treatment of CRPC.

Download Full-text