scholarly journals Potentiation of androgen receptor transcriptional activity by inhibition of histone deacetylation--rescue of transcriptionally compromised mutants

2004 ◽  
Vol 182 (3) ◽  
pp. 377-389 ◽  
Author(s):  
CG Korkmaz ◽  
K Fronsdal ◽  
Y Zhang ◽  
PI Lorenzo ◽  
F Saatcioglu
Keyword(s):  
Androgen Receptor ◽  
Histone Acetylation ◽  
Nuclear Receptor ◽  
Transcriptional Activation ◽  
Transcriptional Activity ◽  
Trichostatin A ◽  
Specific Antigen ◽  
Histone Deacetylation ◽  
Lncap Cells ◽  
Viral Oncoprotein

Androgens are critical in the development and maintenance of the male reproductive system and important in the progression of prostate cancer. The effects of androgens are mediated by the androgen receptor (AR), which is a ligand-modulated transcription factor that belongs to the nuclear receptor superfamily. We and others have previously shown that CREB-binding protein (CBP) can function as a coactivator for AR. Similar to some other nuclear receptor coactivators and/or the proteins that they interact with, CBP has histone acetyl transferase (HAT) activity that is thought to contribute to transcriptional activation by nuclear receptors. We have therefore assessed whether an increase in the histone acetylation status in the cell can influence AR transcriptional activity, by using the histone deacetylase (HDAC) inhibitors (HDACIs) trichostatin A (TSA), sodium butyrate (Na-But) and depsipeptide (FR901228). We found that inhibition of HDAC activity significantly increased the ability of endogenous AR in LNCaP cells, or ectopically expressed AR in HeLa cells, to activate transcription from AR-dependent reporter constructs. In addition, HDACIs increased the androgen-dependent activation of the prostate-specific antigen (PSA) gene in LNCaP cells, an increase that was not due to an increase in nuclear AR protein levels. Moreover, the viral oncoprotein E1A that inhibits CBP HAT activity fully repressed the ability of HDACIs to stimulate AR-mediated transcription, indicating that CBP is involved in this process. Deletional mutagenesis of AR indicated that whereas the AF-2 domain in the C-terminus is dispensable, the AF-1 domain in the N-terminus is required for augmentation of AR action by HDACIs, an observation which is in concordance with the reduced ability of CBP to activate AR N-terminal deletion mutants. Furthermore, HDACI treatment rescued the deficiency in the transactivation potential of AF-2 mutants. Taken together, our findings suggest that a change in the level of histone acetylation of target genes is an important determinant of AR action, possibly mediated by CBP.

scholarly journals Negative Modulation of Androgen Receptor Transcriptional Activity by Daxx

2004 ◽  
Vol 24 (24) ◽  
pp. 10529-10541 ◽  
Author(s):  
Ding-Yen Lin ◽  
Hsin-I Fang ◽  
Ai-Hong Ma ◽  
Yen-Sung Huang ◽  
Yeong-Shiau Pu ◽  
...  
Keyword(s):  
Androgen Receptor ◽  
Prostate Specific Antigen ◽  
Transcriptional Activity ◽  
Specific Antigen ◽  
Antigen Expression ◽  
Lncap Cells ◽  
Negative Regulators ◽  
Amino Terminal

ABSTRACT The transcriptional activity of the androgen receptor (AR) modulated by positive or negative regulators plays a critical role in controlling the growth and survival of prostate cancer cells. Although numerous positive regulators have been identified, negative regulators of AR are less well understood. We report here that Daxx functions as a negative AR coregulator through direct protein-protein interactions. Overexpression of Daxx suppressed AR-mediated promoter activity in COS-1 and LNCaP cells and AR-mediated prostate-specific antigen expression in LNCaP cells. Conversely, downregulation of endogenous Daxx expression by RNA interference enhances androgen-induced prostate-specific antigen expression in LNCaP cells. In vitro and in vivo interaction studies revealed that Daxx binds to both the amino-terminal and the DNA-binding domain of the AR. Daxx proteins interfere with the AR DNA-binding activity both in vitro and in vivo. Moreover, sumoylation of AR at its amino-terminal domain is involved in Daxx interaction and trans-repression. Together, these findings not only provide a novel role of Daxx in controlling AR transactivation activity but also uncover the mechanism underlying sumoylation-dependent transcriptional repression of the AR.

scholarly journals BRG-1 Is Recruited to Estrogen-Responsive Promoters and Cooperates with Factors Involved in Histone Acetylation

2000 ◽  
Vol 20 (20) ◽  
pp. 7541-7549 ◽  
Author(s):  
James DiRenzo ◽  
Yongfeng Shang ◽  
Michael Phelan ◽  
Säid Sif ◽  
Molly Myers ◽  
...  
Keyword(s):  
Histone Acetylation ◽  
Nuclear Receptors ◽  
Transcriptional Activation ◽  
Trichostatin A ◽  
Critical Role ◽  
Histone Deacetylation ◽  
Estrogen Signaling ◽  
Creb Binding Protein ◽  
Histone Deacetylase 1 ◽  
Acetylation State

ABSTRACT Several factors that mediate activation by nuclear receptors also modify the chemical and structural composition of chromatin. Prominent in this diverse group is the steroid receptor coactivator 1 (SRC-1) family, which interact with agonist-bound nuclear receptors, thereby coupling them to multifunctional transcriptional coregulators such as CREB-binding protein (CBP), p300, and PCAF, all of which have potent histone acetyltransferase activity. Additionally factors including the Brahma-related gene 1 (BRG-1) that are involved in the structural remodeling of chromatin also mediate hormone-dependent transcriptional activation by nuclear receptors. Here, we provide evidence that these two distinct mechanisms of coactivation may operate in a collaborative manner. We demonstrate that transcriptional activation by the estrogen receptor (ER) requires functional BRG-1 and that the coactivation of estrogen signaling by either SRC-1 or CBP is BRG-1 dependent. We find that in response to estrogen, ER recruits BRG-1, thereby targeting BRG-1 to the promoters of estrogen-responsive genes in a manner that occurs simultaneous to histone acetylation. Finally, we demonstrate that BRG-1-mediated coactivation of ER signaling is regulated by the state of histone acetylation within a cell. Inhibition of histone deacetylation by trichostatin A dramatically increases BRG-1-mediated coactivation of ER signaling, and this increase is reversed by overexpression of histone deacetylase 1. These studies support a critical role for BRG-1 in ER action in which estrogen stimulates an ER–BRG-1 association coupling BRG-1 to regions of chromatin at the sites of estrogen-responsive promoters and promotes the activity of other recruited factors that alter the acetylation state of chromatin.

scholarly journals Role of Testosterone Levels on the Combinatorial Effect of Boswellia serrata Extract and Enzalutamide on Androgen Dependent LNCaP Cells and in Patient Derived Cells

2021 ◽  
Vol 20 ◽  
pp. 153473542199682
Author(s):  
Prathesha Pillai ◽  
Ginil Kumar Pooleri ◽  
Shantikumar V. Nair
Keyword(s):  
Prostate Cancer ◽  
Androgen Receptor ◽  
Early Stage ◽  
Therapeutic Option ◽  
Specific Antigen ◽  
Cell Killing ◽  
Receptor Expression ◽  
Lncap Cells ◽  
Boswellia Serrata ◽  
Physiological Serum

Co-therapy with herbal extracts along with current clinical drugs is being increasingly recognized as a useful complementary treatment for cancer. The anti-cancer property of the phyto-derivative acetyl-11 keto β boswellic acid (AKBA) has been studied in many cancers, including prostate cancer. However, the whole extract of the gum resin Boswellia serrata (BS) and anti-androgen enzalutamide has not been explored in prostate cancer to date. We hypothesized that the BS extract containing 30% (AKBA) with enzalutamide acted synergistically in the early phase of cancer, especially in LNCaP cells, by inhibiting androgen receptor (AR) and by reducing cell proliferation, and further, that the extract would be superior to the action of the active ingredient AKBA when used alone or in combination with enzalutamide. To test our hypothesis, we treated LNCaP cells with BS extract or AKBA and enzalutamide both individually and in combination to analyze cell viability under different levels of dihydrotestosterone (DHT). The inhibition of androgen receptor (AR) followed by the expression of prostate-specific antigen (PSA) and the efflux mechanism of the cells were analyzed to determine the effect of the combination on the cellular mechanism. Cells derived from prostate cancer patients were also tested with the combination. Only 6 µM enzalutamide along with BS in the range of 4.1 µg/ml to 16.4 µg/ml gave the best synergistic results with nearly 50% cell killing even though standard enzalutamide doses were as high as 48 µM. Cell killing was most effective at intermediate DHT concentrations of approximately 1 nM, which corresponds to normal physiological serum levels of DHT. The Pgp expression level and the androgen receptor expression levels were reduced under the combination treatment; the former helping to minimize drug efflux and the latter by reducing the sensitivity to hormonal changes. Furthermore, the combination reduced the PSA level secreted by the cells. In contrast, AKBA could not achieve the needed synergism for adequate cell killing at equivalent concentrations. The combination of enzalutamide and BS extract containing 30% AKBA because of their synergistic interaction is an attractive therapeutic option for treating early stage (hormone-dependent) prostate cancer and is superior to the use of AKBA alone.

Ethanolic extract of Algerian propolis decreases androgen receptor transcriptional activity in cultured LNCaP cells

2019 ◽  
Vol 189 ◽  
pp. 108-115 ◽  
Author(s):  
Nada Zabaiou ◽  
Allan Fouache ◽  
Amalia Trousson ◽  
Julio Buñay-Noboa ◽  
Geoffroy Marceau ◽  
...  
Keyword(s):  
Androgen Receptor ◽  
Transcriptional Activity ◽  
Ethanolic Extract ◽  
Lncap Cells

Molecular inhibition of histone deacetylation results in major enhancement of the production of IL-1β in response to LPS

2006 ◽  
Vol 290 (3) ◽  
pp. E490-E493 ◽  
Author(s):  
Timothy A. Sato ◽  
Murray D. Mitchell
Keyword(s):  
Dna Methylation ◽  
Receptor Antagonist ◽  
Histone Acetylation ◽  
Trichostatin A ◽  
Cell Types ◽  
Causative Factor ◽  
Histone Deacetylation ◽  
The Other ◽  
Acetylation Status ◽  
Tnf Α

It has been postulated that the progression of human pregnancy to term is, in part, the result of a relative maternal Th2 immunological state. This can be activated in some cell types by modifying DNA methylation and histone acetylation status. We demonstrate that the molecular inhibition of histone deacetylation, using trichostatin A (TSA), in human choriodecidual explants leads to a massive increase in lipopolysaccharide (LPS)-stimulated IL-1β. The inhibition of histone deacetylation had no effect on LPS-stimulated TNF-α production or production of the other cytokines studied (IL-10, IL-1 receptor antagonist). The molecular inhibition of DNA methylation and histone deacetylation, using 5-aza-2′-deoxycytidine and TSA, respectively, in human choriodecidual explants also results in an increase in the basal production of TNF-α but not that of IL-1β. The differential response is unique, and the relative uncoupling of IL-1β and TNF-α responsiveness may have importance in other biological systems and provide new therapeutic targets for pathologies where upregulation of IL-1β is known to be a causative factor.

scholarly journals TAF1 Differentially Enhances Androgen Receptor Transcriptional Activity via Its N-Terminal Kinase and Ubiquitin-Activating and -Conjugating Domains

2010 ◽  
Vol 24 (4) ◽  
pp. 696-708 ◽  
Author(s):  
Peyman Tavassoli ◽  
Latif A. Wafa ◽  
Helen Cheng ◽  
Amina Zoubeidi ◽  
Ladan Fazli ◽  
...  
Keyword(s):  
Androgen Receptor ◽  
Cancer Cells ◽  
Transcriptional Activity ◽  
Specific Antigen ◽  
Tissue Microarrays ◽  
Compensatory Mechanism ◽  
Castration Resistance ◽  
Aberrant Expression ◽  
Androgen Withdrawal ◽  
Prostate Cancers

Abstract Aberrant expression of androgen receptor (AR) coregulators has been linked to progression of prostate cancers to castration resistance. Using the repressed transactivator yeast two-hybrid system, we found that TATA binding protein-associated factor 1 (TAF1) interacted with the AR. In tissue microarrays, TAF1 was shown to steadily increase with duration of neoadjuvant androgen withdrawal and with progression to castration resistance. Glutathione S-transferase pulldown assays established that TAF1 bound through its acetylation and ubiquitin-activating/conjugating domains (E1/E2) directly to the AR N terminus. Coimmunoprecipitation and ChIP assays revealed colocalization of TAF1 and AR on the prostate-specific antigen promoter/enhancer in prostate cancer cells. With respect to modulation of AR activity, overexpression of TAF1 enhanced AR activity severalfold, whereas small interfering RNA knockdown of TAF1 significantly decreased AR transactivation. Although full-length TAF1 showed enhancement of both AR and some generic gene transcriptional activity, selective AR coactivator activity by TAF1 was demonstrated in transactivation experiments using cloned N-terminal kinase and E1/E2 functional domains. In keeping with AR coactivation by the ubiquitin-activating and -conjugating domain, TAF1 was found to greatly increase the cellular amount of polyubiquitinated AR. In conclusion, our results indicate that increased TAF1 expression is associated with progression of human prostate cancers to the lethal castration-resistant state. Because TAF1 is a coactivator of AR that binds and enhances AR transcriptional activity, its overexpression could be part of a compensatory mechanism adapted by cancer cells to overcome reduced levels of circulating androgens.

scholarly journals 134INCOMPLETE HISTONE ACETYLATION OF SOMATIC CHROMATIN IN BOVINE OOCYTES

2004 ◽  
Vol 16 (2) ◽  
pp. 189
Author(s):  
G. Wee ◽  
S.-H. Kim ◽  
K.P. Kim ◽  
S. Yeo ◽  
D.-B. Koo ◽  
...  
Keyword(s):  
Gene Expression ◽  
Somatic Cell ◽  
Histone Acetylation ◽  
Transcriptional Activation ◽  
Linear Models ◽  
Trichostatin A ◽  
Specific Inhibitor ◽  
Early Embryo ◽  
Image Analyzer ◽  
Cell Nuclei

Histone acetylation as an important regulatory mechanism of chromatin structure preceeding zygotic gene expression in early embryo development. After fertilization, transcriptional activation of the embryo begins during the S/G2 phase of the first cell cycle. However, the precise mechanism underlying activation of zygotic transcription remains to be understood, especially in bovine nuclear transfer (NT) embryos. It is known that acetylation of histone H4 lysine 5 (H4K5) represents hyperacetylation state, which is correlated with gene expression. In this study, the acetylation of H4K5 was observed during pronuclear formation by using immunofluorescence analysis with anti-AcH4K5. Our data were analyzed by the general linear models (GLM) procedure of the SAS. In IVF embryos, acetylation of H4K5 occurred on the paternal chromatin at 8h after fertilization but did not occur on the maternal chromatin until 10h after fertilization. Reconstructed oocytes with deactylated somatic cell nuclei began to show signs of acetylation on chromatin at 3h after fusion. When acetylation intensity was calculated using an image analyzer, IVF embryos presented a higher acetylation signal than NT embryos (P<0.05). To induce hyperacetylation in NT embryos, somatic cells were exposed to trichostatin A (TSA, 1μM for 60h), a specific inhibitor of histone deacetylase (HDAC), prior to NT. Acetylated signals of H4K5 increased significantly in TSA-treated cells as compared with non-treated cells (P<0.05). The reconstructed embryos with TSA-treated cells showed a higher fluorescence intensity than the oocytes with non-treated cells (P<0.05), but weak signals compared to IVF embryos. Thus, the results demonstrated low histone acetylation level of somatic cell nuclei after NT during the zygotic progress. Our findings suggest that developmental failures of NT embryos may be due to incomplete chromatin remodeling of somatic cell nuclei during early embryonic development.

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.

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