scholarly journals Androgens Suppress EZH2 Expression Via Retinoblastoma (RB) and p130-Dependent Pathways: A Potential Mechanism of Androgen-Refractory Progression of Prostate Cancer

Endocrinology ◽  
2010 ◽  
Vol 151 (11) ◽  
pp. 5136-5145 ◽  
Author(s):  
Laura R. Bohrer ◽  
Shuai Chen ◽  
Timothy C. Hallstrom ◽  
Haojie Huang
Keyword(s):  
Prostate Cancer ◽  
Androgen Receptor ◽  
Target Genes ◽  
Retinoblastoma Protein ◽  
Lncap Cells ◽  
Normal Prostate ◽  
Androgen Ablation ◽  
Androgen Treatment ◽  
Polycomb Protein ◽  
Ezh2 Expression

Androgens and the androgen receptor are important for both normal prostate development and progression of prostate cancer (PCa). However, the underlying mechanisms are not fully understood. The Polycomb protein enhancer of zeste homolog 2 (EZH2) functions as an epigenetic gene silencer and plays a role in oncogenesis by promoting cell proliferation and invasion. EZH2 has been implicated in human PCa progression, because its expression is often elevated in hormone-refractory PCa. Here, we demonstrated that expression of EZH2 is lower in androgen-sensitive LNCaP PCa cells compared with Rf and C4-2 cells, two androgen-refractory sublines that are derived from LNCaP cells. Androgen ablation by castration increased the level of EZH2 proteins in LNCaP xenografts in mice. In contrast, treatment of LNCaP cells in culture with the synthetic androgen methyltrieolone (R1881) at doses of 1 nm or higher suppressed EZH2 expression. Moreover, our data suggest that androgen repression of EZH2 requires a functional androgen receptor and this effect is mediated through the retinoblastoma protein and its related protein p130. We further showed that androgen treatment not only increases expression of EZH2 target genes DAB2IP and E-cadherin but also affects LNCaP cell migration. Our results reveal that androgens function as an epigenetic regulator in prostatic cells by repression of EZH2 expression through the retinoblastoma protein and p130-dependent pathways. Our findings also suggest that blockade of EZH2 derepression during androgen deprivation therapy may represent an effective tactic for the treatment of androgen-refractory PCa.

Androgen receptor (AR) modulation strategies for recurrent prostate cancer (PC) without androgen suppression

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 4657-4657
Author(s):  
A. C. Ferrari ◽  
L. Wang ◽  
X. Liu ◽  
X. Liu
Keyword(s):  
Prostate Cancer ◽  
Dna Methylation ◽  
Androgen Receptor ◽  
Target Genes ◽  
Trichostatin A ◽  
Second Messengers ◽  
Growth Factor Receptor ◽  
Global Strategy ◽  
Lncap Cells ◽  
Aberrant Expression

4657 Background: Prostate cancer (PC) progression is tightly linked to aberrant expression and activation of the androgen receptor (AR) gene and protein. Activation of AR is supported by increased/promiscuous ligand-binding to AR and cross-talk with activated growth factor receptor pathways and intracellular second messengers. Overexpression of AR mRNA has been linked to increased Sp1 and/or loss of AR suppressor protein (ARS) binding to the AR promoter (Oncogene, 2004). The purpose of this work was to test the hypothesis that down-regulation of AR levels and inhibition of ligand-dependent and ligand-independent activation can control androgen-dependent (AD) and -independent (AI) PC cells growth and sensitivity to apoptosis. Methods: AD and AI LNCaP cells treated with inhibitors of signal transduction pathways or inhibitors of Sp1, HDAC and/or DNA methylation were assessed for growth and apoptosis in the presence or absence of the anti-androgen bicalutamide. The combination index(CI)(CalcuSyn program) was used to measure activity: CI>1=antagonistic; CI=1, additive; CI<1,synergistic. Pertinent proteins were evaluated by Western blot. AR transactivation by transfection assays using AR and PSA reporter constructs. Results: Combinations of bicalutamide with inhibitors of Akt (Rapmycin), Sp1 (Mithramycin), HDAC (trichostatin A, Sodium butyrate) and DNA methylation (5’-Aza) were synergistic against AD and AI LNCaP cells while EGFR (Iressa) was additive. Decreased AR expression/phosphorylation and transactivation activity preceded the biologic effect. Some triplet combinations enhanced further AR modulation and biologic activity. Conclusion: a global strategy to simultaneously reduce AR levels and activation activity of downstream target genes might be an effective approach against androgen-dependent and androgen-independent clones present in recurrent, high-risk PC patients with potential to spare or postpone the need for castration. No significant financial relationships to disclose.

scholarly journals Leupaxin, a Novel Coactivator of the Androgen Receptor, Is Expressed in Prostate Cancer and Plays a Role in Adhesion and Invasion of Prostate Carcinoma Cells

2008 ◽  
Vol 22 (7) ◽  
pp. 1606-1621 ◽  
Author(s):  
Silke Kaulfuss ◽  
Michal Grzmil ◽  
Bernhard Hemmerlein ◽  
Paul Thelen ◽  
Stefan Schweyer ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Androgen Receptor ◽  
Nuclear Export ◽  
Mutational Analysis ◽  
Specific Antigen ◽  
High Rate ◽  
Dependent Manner ◽  
Lncap Cells ◽  
Normal Prostate ◽  
Progression Marker

Abstract In the present study, we demonstrate that leupaxin mRNA is overexpressed in prostate cancer (PCa) as compared with normal prostate tissue by using cDNA arrays and quantitative RT-PCR analyses. Moderate to strong expression of leupaxin protein was detected in approximately 22% of the PCa tissue sections analyzed, and leupaxin expression intensities were found to be significantly correlated with Gleason patterns/scores. In addition, different leupaxin expression levels were observed in PCa cell lines, and at the subcellular level, leupaxin was usually localized in focal adhesion sites. Furthermore, mutational analysis and transfection experiments of LNCaP cells using different green fluorescent protein-leupaxin constructs demonstrated that leupaxin contains functional nuclear export signals in its LD3 and LD4 motifs, thus shuttling between the cytoplasm and the nucleus. We could also demonstrate for the first time that leupaxin interacts with the androgen receptor in a ligand-dependent manner and serves as a transcriptional activator of this hormone receptor in PCa cells. Down-regulation of leupaxin expression using RNA interference in LNCaP cells resulted in a high rate of morphological changes, detachment, spontaneous apoptosis, and a reduction of prostate-specific antigen secretion. In contrast, knockdown of leupaxin expression in androgen-independent PC-3 and DU 145 cells induced a significant decrease of both the invasive capacity and motility. Our results therefore indicate that leupaxin could serve as a potential progression marker for a subset of PCa and may represent a novel coactivator of the androgen receptor. Leupaxin could function as a putative target for therapeutic interventions of a subset of advanced PCa.

scholarly journals The Immunophilin Ligands Cyclosporin A and FK506 Suppress Prostate Cancer Cell Growth by Androgen Receptor-Dependent and -Independent Mechanisms

Endocrinology ◽  
2007 ◽  
Vol 148 (10) ◽  
pp. 4716-4726 ◽  
Author(s):  
Sumudra Periyasamy ◽  
Manya Warrier ◽  
Manoranjani P. M. Tillekeratne ◽  
Weinian Shou ◽  
Edwin R. Sanchez
Keyword(s):  
Prostate Cancer ◽  
Androgen Receptor ◽  
Cell Growth ◽  
Cyclosporin A ◽  
Cell Lines ◽  
Cancer Cell ◽  
Prostate Cancer Cell ◽  
Lncap Cells ◽  
Androgen Ablation ◽  
Prostate Cells

The androgen receptor (AR) contributes to growth of prostate cancer even under conditions of androgen ablation. Thus, new strategies to target AR activity are needed. The AR interacts with the immunophilin FK506-binding protein 52 (FKBP52), and studies in the FKBP52 knockout mouse have shown that this protein is essential to AR activity in the prostate. Therefore, we tested whether the immunophilin ligand FK506 affected AR activity in prostate cancer cell lines. We also tested the hypothesis that the AR interacts with another immunophilin, cyclophilin 40 (Cyp40), and is regulated by its cognate ligand cyclosporin A (CsA). We show that levels of FKBP52, FKBP51, Cyp40, and a related co-chaperone PP5 were much higher in prostate cancer cells lines [(LNCaP), PC-3, and DU145] compared with primary prostate cells, and that the AR of LNCaP cells can interact with Cyp40. In the absence of androgen, CsA caused inhibition of cell growth in the AR-positive LNCaP and AR-negative PC-3 and DU145 cell lines. Interestingly, FK506 only inhibited LNCaP cells, suggesting a dependence on the AR for this effect. Both CsA and FK506 inhibited growth without inducing apoptosis. In LNCaP cells, CsA completely blocked androgen-stimulated growth, whereas FK506 was partially effective. Further studies in LNCaP cells revealed that CsA and FK506 were able to block or attenuate several stages of AR signaling, including hormone binding, nuclear translocation, and activity at several AR-responsive reporter and endogenous genes. These findings provide the first evidence that CsA and FK506 can negatively modulate proliferation of prostate cells in vitro. Immunophilins may now serve as new targets to disrupt AR-mediated prostate cancer growth.

scholarly journals miR-22 and miR-29a Are Members of the Androgen Receptor Cistrome Modulating LAMC1 and Mcl-1 in Prostate Cancer

2015 ◽  
Vol 29 (7) ◽  
pp. 1037-1054 ◽  
Author(s):  
Lorenza Pasqualini ◽  
Huajie Bu ◽  
Martin Puhr ◽  
Narisu Narisu ◽  
Johannes Rainer ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Androgen Receptor ◽  
Target Genes ◽  
Myeloid Cell ◽  
Specific Expression ◽  
Normal Prostate ◽  
Growth And Survival ◽  
Downstream Target ◽  
Additional Information ◽  
Induced Apoptosis

Abstract The normal prostate as well as early stages and advanced prostate cancer (PCa) require a functional androgen receptor (AR) for growth and survival. The recent discovery of microRNAs (miRNAs) as novel effector molecules of AR disclosed the existence of an intricate network between AR, miRNAs and downstream target genes. In this study DUCaP cells, characterized by high content of wild-type AR and robust AR transcriptional activity, were chosen as the main experimental model. By integrative analysis of chromatin immunoprecipitation-sequencing (ChIP-seq) and microarray expression profiling data, miRNAs putatively bound and significantly regulated by AR were identified. A direct AR regulation of miR-22, miR-29a, and miR-17-92 cluster along with their host genes was confirmed. Interestingly, endogenous levels of miR-22 and miR-29a were found to be reduced in PCa cells expressing AR. In primary tumor samples, miR-22 and miR-29a were less abundant in the cancerous tissue compared with the benign counterpart. This specific expression pattern was associated with a differential DNA methylation of the genomic AR binding sites. The identification of laminin gamma 1 (LAMC1) and myeloid cell leukemia 1 (MCL1) as direct targets of miR-22 and miR-29a, respectively, suggested a tumor-suppressive role of these miRNAs. Indeed, transfection of miRNA mimics in PCa cells induced apoptosis and diminished cell migration and viability. Collectively, these data provide additional information regarding the complex regulatory machinery that guides miRNAs activity in PCa, highlighting an important contribution of miRNAs in the AR signaling.

scholarly journals Response to Androgens and Androgen Receptor Antagonists in the Presence of Cytokines in Prostate Cancer

Cancers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2944
Author(s):  
Zoran Culig
Keyword(s):  
Prostate Cancer ◽  
Androgen Receptor ◽  
Cellular Response ◽  
Target Genes ◽  
Neuroendocrine Differentiation ◽  
Cancer Tissue ◽  
Androgen Ablation ◽  
Prostate Cancers

Non-steroidal anti-androgens have a major role in the treatment of non-localized prostate cancer. Interleukins are involved in the regulation of many cellular functions in prostate cancer and also modify cellular response to anti-androgens. A specific role of selected IL is presented in this review. IL-8 is a cytokine expressed in prostate cancer tissue and microenvironment and promotes proliferation and androgen receptor-mediated transcription. In contrast, IL-1 displays negative effects on expression of androgen receptor and its target genes. A subgroup of prostate cancers show neuroendocrine differentiation, which may be in part stimulated by androgen ablation. A similar effect was observed after treatment of cells with IL-10. Another cytokine which is implicated in regulation of androgenic response is IL-23, secreted by myeloid cells. Most studies on androgens and IL were carried out with IL-6, which acts through the signal transducer and activator of the transcription (STAT) factor pathway. IL-6 is implicated in resistance to enzalutamide. Activation of the STAT-3 pathway is associated with increased cellular stemness. IL-6 activation of the androgen receptor in some prostate cancers is associated with increased growth in vitro and in vivo. Molecules such as galiellalactone or niclosamide have an inhibitory effect on both androgen receptor and STAT-3 pathways.

scholarly journals Inhibition of MAPK-signaling pathway promotes the interaction of the corepressor SMRT with the human androgen receptor and mediates repression of prostate cancer cell growth in the presence of antiandrogens

2009 ◽  
Vol 42 (5) ◽  
pp. 429-435 ◽  
Author(s):  
Michael Eisold ◽  
Mohammad Asim ◽  
Hanna Eskelinen ◽  
Thomas Linke ◽  
Aria Baniahmad
Keyword(s):  
Prostate Cancer ◽  
Androgen Receptor ◽  
Cell Growth ◽  
Signaling Pathway ◽  
Specific Inhibitor ◽  
Mapk Signaling ◽  
Lncap Cells ◽  
Cancer Cell Growth ◽  
Normal Prostate ◽  
Prostate Epithelial Cells

Prostate cancer is one of the most prominent malignancies of elderly males. The growth of normal prostate and prostate cancer (PCa) cells depend on functional androgen receptor (AR), a ligand controlled transcription factor and member of the nuclear receptor superfamily. Binding of agonistic ligand enhances the transactivation function of AR and hence promotes the growth of prostate epithelial cells. We have earlier shown that AR antagonistic ligands such as cyproterone acetate (CPA) promote the recruitment of transcriptional corepressors such as silencing mediator of retinoid and thyroid receptor (SMRT) leading to repression of AR transactivation in non-PCa cells. Unfortunately, however, in LNCaP PCa cells, CPA functions as an agonist and thereby increases AR transactivation function. Here, we show that activated MEK signaling cascade inhibits functional recruitment of corepressor SMRT to CPA-bound AR in PCa cells. Chemical blockade of MEK kinase using a specific inhibitor U0126 increases the interaction and hence repression of AR by the corepressor SMRT in LNCaP PCa cells. This inhibition also results in enhanced antagonistic behavior of CPA as assessed by reporter and cell-growth assays. Moreover, the growth of LNCaP cells stably overexpressing SMRT was more robustly inhibited in the presence of CPA and U1026. In line with this, the growth rate of LNCaP cells was decelerated in the presence of both CPA and U0126. This suggests that activated MEK signaling pathway attenuates the functional recruitment of corepressor SMRT to AR induced by antagonists and thus indicates the important role of corepressors in mediating repression of both AR transactivation and PCa cell growth by antagonists. Furthermore, these findings suggest that combining receptor antagonists with signaling inhibitors could be a beneficial approach for PCa treatment.

The significance of Her2 on androgen receptor protein stability in the transition of androgen requirement in prostate cancer cells

2011 ◽  
Vol 300 (5) ◽  
pp. E902-E908 ◽  
Author(s):  
Fu-Ning Hsu ◽  
Min-Shiou Yang ◽  
Eugene Lin ◽  
Chun-Fu Tseng ◽  
Ho Lin
Keyword(s):  
Prostate Cancer ◽  
Cell Cycle ◽  
Androgen Receptor ◽  
Protein Stability ◽  
Cancer Cells ◽  
Cell Lines ◽  
Lncap Cells ◽  
Prostate Cancer Cells ◽  
Androgen Ablation ◽  
Androgen Independent

Androgen ablation therapy is the most common strategy for suppressing prostate cancer progression; however, tumor cells eventually escape androgen dependence and progress to an androgen-independent phase. The androgen receptor (AR) plays a pivotal role in this transition. To address this transition mystery in prostate cancer, we established an androgen-independent prostate cancer cell line (LNCaPdcc), by long-term screening of LNCaP cells in androgen-deprived conditions, to investigate changes of molecular mechanisms before and after androgen withdrawal. We found that LNCaPdcc cells displayed a neuroendocrine morphology, less aggressive growth, and lower expression levels of cell cycle-related factors, although the cell cycle distribution was similar to parental LNCaP cells. Notably, higher protein expression of AR, phospho-Ser81-AR, and PSA in LNCaPdcc cells were observed. The nuclear distribution and protein stability of AR increased in LNCaPdcc cells. In addition, cell proliferation results exhibited the biphasic nature of the androgen (R1881) effect in two cell lines. On the other hand, LNCaPdcc cells expressed higher levels of Her2, phospho-Tyr1221/1222-Her2, ErbB3, and ErbB4 proteins than parental LNCaP cells. These two cell lines exhibited distinct responses to Her2 activation (by heregulin treatment) on Her2 phosphorylation and Her2 inhibition (by AG825 or Herceptin treatments) on proliferation. In addition, the Her2 inhibitor more effectively caused AR degradation and diminished AR Ser81 phosphorylation in LNCaPdcc cells. Taken together, our data demonstrate that Her2 plays an important role in the support of AR protein stability in the transition of androgen requirement in prostate cancer cells. We hope these findings will provide novel insight into the treatment of hormone-refractory prostate cancer.

scholarly journals Cytostatic Action of Novel Histone Deacetylase Inhibitors in Androgen Receptor-Null Prostate Cancer Cells

2021 ◽  
Vol 14 (2) ◽  
pp. 103
Author(s):  
Zohaib Rana ◽  
Joel D. A. Tyndall ◽  
Muhammad Hanif ◽  
Christian G. Hartinger ◽  
Rhonda J. Rosengren
Keyword(s):  
Prostate Cancer ◽  
Androgen Receptor ◽  
Cancer Cells ◽  
Hdac Inhibitors ◽  
G1 Arrest ◽  
Prostate Cancer Cells ◽  
Prostate Tumors ◽  
Normal Prostate ◽  
Pc3 Cells ◽  
Du145 Cells

Androgen receptor (AR)-null prostate tumors have been observed in 11–24% of patients. Histone deacetylases (HDACs) are overexpressed in prostate tumors. Therefore, HDAC inhibitors (Jazz90 and Jazz167) were examined in AR-null prostate cancer cell lines (PC3 and DU145). Both Jazz90 and Jazz167 inhibited the growth of PC3 and DU145 cells. Jazz90 and Jazz167 were more active in PC3 cells and DU145 cells in comparison to normal prostate cells (PNT1A) and showed a 2.45- and 1.30-fold selectivity and higher cytotoxicity toward DU145 cells, respectively. Jazz90 and Jazz167 reduced HDAC activity by ~60% at 50 nM in PC3 lysates. At 4 μM, Jazz90 and Jazz167 increased acetylation in PC3 cells by 6- to 8-fold. Flow cytometry studies on the cell phase distribution demonstrated that Jazz90 causes a G0/G1 arrest in AR-null cells, whereas Jazz167 leads to a G0/G1 arrest in DU145 cells. However, apoptosis only occurred at a maximum of 7% of the total cell population following compound treatments in PC3 and DU145 cells. There was a reduction in cyclin D1 and no significant changes in bcl-2 in DU145 and PC3 cells. Overall, the results showed that Jazz90 and Jazz167 function as cytostatic HDAC inhibitors in AR-null prostate cancer cells.

scholarly journals Chromatin-directed proteomics-identified network of endogenous androgen receptor in prostate cancer cells

Oncogene ◽  
2021 ◽  
Author(s):  
Kaisa-Mari Launonen ◽  
Ville Paakinaho ◽  
Gianluca Sigismondo ◽  
Marjo Malinen ◽  
Reijo Sironen ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Androgen Receptor ◽  
Target Genes ◽  
Epithelial Mesenchymal Transition ◽  
Protein A ◽  
Chorioallantoic Membrane ◽  
Chromatin Accessibility ◽  
Castration Resistant Prostate Cancer ◽  
Novel Therapy ◽  
Mesenchymal Transition

AbstractTreatment of prostate cancer confronts resistance to androgen receptor (AR)-targeted therapies. AR-associated coregulators and chromatin proteins hold a great potential for novel therapy targets. Here, we employed a powerful chromatin-directed proteomics approach termed ChIP-SICAP to uncover the composition of chromatin protein network, the chromatome, around endogenous AR in castration resistant prostate cancer (CRPC) cells. In addition to several expected AR coregulators, the chromatome contained many nuclear proteins not previously associated with the AR. In the context of androgen signaling in CRPC cells, we further investigated the role of a known AR-associated protein, a chromatin remodeler SMARCA4 and that of SIM2, a transcription factor without a previous association with AR. To understand their role in chromatin accessibility and AR target gene expression, we integrated data from ChIP-seq, RNA-seq, ATAC-seq and functional experiments. Despite the wide co-occurrence of SMARCA4 and AR on chromatin, depletion of SMARCA4 influenced chromatin accessibility and expression of a restricted set of AR target genes, especially those involved in cell morphogenetic changes in epithelial-mesenchymal transition. The depletion also inhibited the CRPC cell growth, validating SMARCA4’s functional role in CRPC cells. Although silencing of SIM2 reduced chromatin accessibility similarly, it affected the expression of a much larger group of androgen-regulated genes, including those involved in cellular responses to external stimuli and steroid hormone stimulus. The silencing also reduced proliferation of CRPC cells and tumor size in chick embryo chorioallantoic membrane assay, further emphasizing the importance of SIM2 in CRPC cells and pointing to the functional relevance of this potential prostate cancer biomarker in CRPC cells. Overall, the chromatome of AR identified in this work is an important resource for the field focusing on this important drug target.

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