1
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Mahapatra D, Franzosa JA, Roell K, Kuenemann MA, Houck KA, Reif DM, Fourches D, Kullman SW. Confirmation of high-throughput screening data and novel mechanistic insights into VDR-xenobiotic interactions by orthogonal assays. Sci Rep 2018; 8:8883. [PMID: 29891985 PMCID: PMC5995905 DOI: 10.1038/s41598-018-27055-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 05/30/2018] [Indexed: 01/21/2023] Open
Abstract
High throughput screening (HTS) programs have demonstrated that the Vitamin D receptor (VDR) is activated and/or antagonized by a wide range of structurally diverse chemicals. In this study, we examined the Tox21 qHTS data set generated against VDR for reproducibility and concordance and elucidated functional insights into VDR-xenobiotic interactions. Twenty-one potential VDR agonists and 19 VDR antagonists were identified from a subset of >400 compounds with putative VDR activity and examined for VDR functionality utilizing select orthogonal assays. Transient transactivation assay (TT) using a human VDR plasmid and Cyp24 luciferase reporter construct revealed 20/21 active VDR agonists and 18/19 active VDR antagonists. Mammalian-2-hybrid assay (M2H) was then used to evaluate VDR interactions with co-activators and co-regulators. With the exception of a select few compounds, VDR agonists exhibited significant recruitment of co-regulators and co-activators whereas antagonists exhibited considerable attenuation of recruitment by VDR. A unique set of compounds exhibiting synergistic activity in antagonist mode and no activity in agonist mode was identified. Cheminformatics modeling of VDR-ligand interactions were conducted and revealed selective ligand VDR interaction. Overall, data emphasizes the molecular complexity of ligand-mediated interactions with VDR and suggest that VDR transactivation may be a target site of action for diverse xenobiotics.
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Affiliation(s)
- Debabrata Mahapatra
- Comparative Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA
| | - Jill A Franzosa
- National Center for Computational Toxicology, Office of Research and Development, U.S. Environmental Protection Agency, RTP, Raleigh, North Carolina, USA
| | - Kyle Roell
- Department of Chemistry, Bioinformatics Research Center, North Carolina State University, Raleigh, North Carolina, USA
| | - Melaine Agnes Kuenemann
- Department of Chemistry, Bioinformatics Research Center, North Carolina State University, Raleigh, North Carolina, USA
| | - Keith A Houck
- National Center for Computational Toxicology, Office of Research and Development, U.S. Environmental Protection Agency, RTP, Raleigh, North Carolina, USA
| | - David M Reif
- Department of Chemistry, Bioinformatics Research Center, North Carolina State University, Raleigh, North Carolina, USA
| | - Denis Fourches
- Department of Chemistry, Bioinformatics Research Center, North Carolina State University, Raleigh, North Carolina, USA
| | - Seth W Kullman
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, USA. .,Program in Environmental and Molecular Toxicology, North Carolina State University, Raleigh, North Carolina, USA.
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2
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Le Guével R, Oger F, Martinez-Jimenez CP, Bizot M, Gheeraert C, Firmin F, Ploton M, Kretova M, Palierne G, Staels B, Barath P, Talianidis I, Lefebvre P, Eeckhoute J, Salbert G. Inactivation of the Nuclear Orphan Receptor COUP-TFII by Small Chemicals. ACS Chem Biol 2017; 12:654-663. [PMID: 28059499 DOI: 10.1021/acschembio.6b00593] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Chicken ovalbumin upstream promoter-transcription factor II (COUP-TFII/NR2F2) is an orphan member of the nuclear receptor family of transcription factors whose activities are modulated upon binding of small molecules into an hydrophobic ligand-binding pocket (LBP). Although the LBP of COUP-TFII is filled with aromatic amino-acid side chains, alternative modes of ligand binding could potentially lead to regulation of the orphan receptor. Here, we screened a synthetic and natural compound library in a yeast one-hybrid assay and identified 4-methoxynaphthol as an inhibitor of COUP-TFII. This synthetic inhibitor was able to counteract processes either positively or negatively regulated by COUP-TFII in different mammalian cell systems. Hence, we demonstrate that the true orphan receptor COUP-TFII can be targeted by small chemicals which could be used to study the physiological functions of COUP-TFII or to counteract detrimental COUP-TFII activities in various pathological conditions.
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Affiliation(s)
- Rémy Le Guével
- Université Rennes 1, F-35042 Rennes, France
- UMR6290 CNRS,
Team SP@RTE, Campus de Beaulieu, F-35042 Rennes, France
- SFR Biosit, UMS
3480 CNRS, US 018 INSERM, Campus de
Villejean, F-35043 Rennes, France
| | - Frédérik Oger
- European Genomic
Institute for Diabetes (EGID), FR 3508, F-59000 Lille, France
- Inserm
UMR U1011, F-59000 Lille, France
- Université Lille 2, F-59000 Lille, France
- Institut Pasteur de Lille, F-59019 Lille, France
| | | | - Maud Bizot
- Université Rennes 1, F-35042 Rennes, France
- UMR6290 CNRS,
Team SP@RTE, Campus de Beaulieu, F-35042 Rennes, France
| | - Céline Gheeraert
- European Genomic
Institute for Diabetes (EGID), FR 3508, F-59000 Lille, France
- Inserm
UMR U1011, F-59000 Lille, France
- Université Lille 2, F-59000 Lille, France
- Institut Pasteur de Lille, F-59019 Lille, France
| | - François Firmin
- European Genomic
Institute for Diabetes (EGID), FR 3508, F-59000 Lille, France
- Inserm
UMR U1011, F-59000 Lille, France
- Université Lille 2, F-59000 Lille, France
- Institut Pasteur de Lille, F-59019 Lille, France
| | - Maheul Ploton
- European Genomic
Institute for Diabetes (EGID), FR 3508, F-59000 Lille, France
- Inserm
UMR U1011, F-59000 Lille, France
- Université Lille 2, F-59000 Lille, France
- Institut Pasteur de Lille, F-59019 Lille, France
| | - Miroslava Kretova
- Cancer
Research Institute BMC, Slovak Academy of Sciences, Dúbravská
cesta 9, SK-845 05 Bratislava, Slovak Republic
| | - Gaëlle Palierne
- Université Rennes 1, F-35042 Rennes, France
- UMR6290 CNRS,
Team SP@RTE, Campus de Beaulieu, F-35042 Rennes, France
| | - Bart Staels
- European Genomic
Institute for Diabetes (EGID), FR 3508, F-59000 Lille, France
- Inserm
UMR U1011, F-59000 Lille, France
- Université Lille 2, F-59000 Lille, France
- Institut Pasteur de Lille, F-59019 Lille, France
| | - Peter Barath
- Cancer
Research Institute BMC, Slovak Academy of Sciences, Dúbravská
cesta 9, SK-845 05 Bratislava, Slovak Republic
| | | | - Philippe Lefebvre
- European Genomic
Institute for Diabetes (EGID), FR 3508, F-59000 Lille, France
- Inserm
UMR U1011, F-59000 Lille, France
- Université Lille 2, F-59000 Lille, France
- Institut Pasteur de Lille, F-59019 Lille, France
| | - Jérôme Eeckhoute
- European Genomic
Institute for Diabetes (EGID), FR 3508, F-59000 Lille, France
- Inserm
UMR U1011, F-59000 Lille, France
- Université Lille 2, F-59000 Lille, France
- Institut Pasteur de Lille, F-59019 Lille, France
| | - Gilles Salbert
- Université Rennes 1, F-35042 Rennes, France
- UMR6290 CNRS,
Team SP@RTE, Campus de Beaulieu, F-35042 Rennes, France
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3
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Bacallao K, Plaza-Parrochia F, Cerda A, Gabler F, Romero C, Vantman D, Vega M. Levels of Regulatory Proteins Associated With Cell Proliferation in Endometria From Untreated Patients Having Polycystic Ovarian Syndrome With and Without Endometrial Hyperplasia. Reprod Sci 2015; 23:211-8. [DOI: 10.1177/1933719115597762] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- K. Bacallao
- Department of Obstetrics and Gynecology, School of Medicine, University of Chile Clinical Hospital, Santiago, Chile
- Interdisciplinary Stem Cell Institute, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - F. Plaza-Parrochia
- Department of Obstetrics and Gynecology, School of Medicine, University of Chile Clinical Hospital, Santiago, Chile
| | - A. Cerda
- Department of Obstetrics and Gynecology, School of Medicine, University of Chile Clinical Hospital, Santiago, Chile
| | - F. Gabler
- Department of Pathology, School of Medicine, University of Chile, San Borja Arriarán Clinical Hospital, Santiago, Chile
| | - C. Romero
- Department of Obstetrics and Gynecology, School of Medicine, University of Chile Clinical Hospital, Santiago, Chile
| | - D. Vantman
- Department of Obstetrics and Gynecology, School of Medicine, University of Chile Clinical Hospital, Santiago, Chile
| | - M. Vega
- Department of Obstetrics and Gynecology, School of Medicine, University of Chile Clinical Hospital, Santiago, Chile
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4
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Schmidt A, Meissner RS, Gentile MA, Chisamore MJ, Opas EE, Scafonas A, Cusick TE, Gambone C, Pennypacker B, Hodor P, Perkins JJ, Bai C, Ferraro D, Bettoun DJ, Wilkinson HA, Alves SE, Flores O, Ray WJ. Identification of an anabolic selective androgen receptor modulator that actively induces death of androgen-independent prostate cancer cells. J Steroid Biochem Mol Biol 2014; 143:29-39. [PMID: 24565564 DOI: 10.1016/j.jsbmb.2014.02.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 02/10/2014] [Accepted: 02/14/2014] [Indexed: 11/26/2022]
Abstract
Prostate cancer (PCa) initially responds to inhibition of androgen receptor (AR) signaling, but inevitably progresses to hormone ablation-resistant disease. Much effort is focused on optimizing this androgen deprivation strategy by improving hormone depletion and AR antagonism. However we found that bicalutamide, a clinically used antiandrogen, actually resembles a selective AR modulator (SARM), as it partially regulates 24% of endogenously 5α-dihydrotestosterone (DHT)-responsive genes in AR(+) MDA-MB-453 breast cancer cells. These data suggested that passive blocking of all AR functions is not required for PCa therapy. Hence, we adopted an active strategy that calls for the development of novel SARMs, which induce a unique gene expression profile that is intolerable to PCa cells. Therefore, we screened 3000 SARMs for the ability to arrest the androgen-independent growth of AR(+) 22Rv1 and LNCaP PCa cells but not AR(-) PC3 or DU145 cells. We identified only one such compound; the 4-aza-steroid, MK-4541, a potent and selective SARM. MK-4541 induces caspase-3 activity and cell death in both androgen-independent, AR(+) PCa cell lines but spares AR(-) cells or AR(+) non-PCa cells. This activity correlates with its promoter context- and cell-type dependent transcriptional effects. In rats, MK-4541 inhibits the trophic effects of DHT on the prostate, but not the levator ani muscle, and triggers an anabolic response in the periosteal compartment of bone. Therefore, MK-4541 has the potential to effectively manage prostatic hypertrophic diseases owing to its antitumor SARM-like mechanism, while simultaneously maintaining the anabolic benefits of natural androgens.
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MESH Headings
- Anabolic Agents/chemistry
- Anabolic Agents/pharmacology
- Androgen Receptor Antagonists/pharmacology
- Androgens/pharmacology
- Animals
- Apoptosis/drug effects
- Azasteroids/chemistry
- Azasteroids/pharmacology
- Blotting, Western
- Breast Neoplasms/drug therapy
- Breast Neoplasms/metabolism
- Breast Neoplasms/pathology
- Carbamates/chemistry
- Carbamates/pharmacology
- Cell Proliferation/drug effects
- Combinatorial Chemistry Techniques
- Female
- Humans
- Male
- Mice
- Mice, Inbred C57BL
- Prostatic Neoplasms/drug therapy
- Prostatic Neoplasms/metabolism
- Prostatic Neoplasms/pathology
- Prostatic Neoplasms, Castration-Resistant/drug therapy
- Prostatic Neoplasms, Castration-Resistant/metabolism
- Prostatic Neoplasms, Castration-Resistant/pathology
- RNA, Messenger/genetics
- Rats
- Rats, Sprague-Dawley
- Real-Time Polymerase Chain Reaction
- Receptors, Androgen/chemistry
- Receptors, Androgen/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Tumor Cells, Cultured
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Affiliation(s)
- Azriel Schmidt
- Departments of Molecular Endocrinology, West Point, PA 19486, USA.
| | | | | | | | - Evan E Opas
- Departments of Molecular Endocrinology, West Point, PA 19486, USA
| | - Angela Scafonas
- Departments of Molecular Endocrinology, West Point, PA 19486, USA
| | - Tara E Cusick
- Departments of Molecular Endocrinology, West Point, PA 19486, USA; Departments of Medicinal Chemistry, West Point, PA 19486, USA; Departments of Molecular Profiling Merck & Co., West Point, PA 19486, USA
| | - Carlo Gambone
- Departments of Molecular Endocrinology, West Point, PA 19486, USA
| | | | - Paul Hodor
- Departments of Molecular Profiling Merck & Co., West Point, PA 19486, USA
| | - James J Perkins
- Departments of Medicinal Chemistry, West Point, PA 19486, USA
| | - Chang Bai
- Departments of Molecular Endocrinology, West Point, PA 19486, USA
| | - Damien Ferraro
- Departments of Molecular Endocrinology, West Point, PA 19486, USA
| | - David J Bettoun
- Departments of Molecular Endocrinology, West Point, PA 19486, USA
| | | | - Stephen E Alves
- Departments of Molecular Endocrinology, West Point, PA 19486, USA
| | - Osvaldo Flores
- Departments of Molecular Endocrinology, West Point, PA 19486, USA
| | - William J Ray
- Departments of Molecular Endocrinology, West Point, PA 19486, USA.
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5
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Ko YM, Wu TY, Wu YC, Chang FR, Guh JY, Chuang LY. Annonacin induces cell cycle-dependent growth arrest and apoptosis in estrogen receptor-α-related pathways in MCF-7 cells. JOURNAL OF ETHNOPHARMACOLOGY 2011; 137:1283-1290. [PMID: 21840388 DOI: 10.1016/j.jep.2011.07.056] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 07/11/2011] [Accepted: 07/28/2011] [Indexed: 05/31/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Tamoxifen resistance is common in estrogen receptor-α (ERα)-positive breast cancers. Pawpaw and soursop are anticancer annonaceous plants in complementary medicine. Thus, we studied the effects of annonacin, an annonaceous acetogenin, in breast cancer cells. MATERIALS AND METHODS Cell growth and ERα-related pathways were studied. The effects of annonacin were tested in MCF-7 xenografts in nude mice. RESULTS In ERα-positive MCF-7 cells, annonacin (half-effective dose ED(50) = 0.31 μM) and 4-hydroxytamoxifen (ED(50) = 1.13 μM) decreased cell survival whereas annonacin (0.5-1 μM) increased cell death at 48 h. Annonacin and 4-hydroxytamoxifen were additive in inhibiting cell survival. Annonacin (0.1 μM) induced G(0)/G(1) growth arrest while increasing p21(WAF1) and p27(kip1) and decreasing cyclin D1 protein expression. Annonacin (0.1μM) decreased cyclin D1 protein expression more than 4-hydroxytamoxifen (1 μM). Annonacin (0.1 μM) increased apoptosis while decreasing Bcl-2 protein expression. The combination of annonacin (0.1 μM) and 4-hydroxytamoxifen (1 μM) decreased Bcl-2 protein expression and ERα transcriptional activity more than annonacin (0.1 μM) did alone. Annonacin, but not 4-hydroxytamoxifen, decreased ERα protein expression. Moreover, annonacin decreased phosphorylation of ERK1/2, JNK and STAT3. In nude mice, annonacin decreased MCF-7 xenograft tumor size at 7-22 days. Moreover, annonacin decreased ERα, cyclin D1 and Bcl-2 protein expression in the xenograft at 22 days. CONCLUSIONS Annonacin induced growth arrest and apoptosis in ERα-related pathways in MCF-7 cells. Annonacin and 4-hydroxytamoxifen were additive in inhibiting cell survival and ERα transcriptional activity. Moreover, annonacin attenuated MCF-7 xenograft tumor growth while inhibiting ERα, cyclin D1 and Bcl-2 protein expressions in nude mice.
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Affiliation(s)
- Yu-Min Ko
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC
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6
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Wardell SE, Marks JR, McDonnell DP. The turnover of estrogen receptor α by the selective estrogen receptor degrader (SERD) fulvestrant is a saturable process that is not required for antagonist efficacy. Biochem Pharmacol 2011; 82:122-30. [PMID: 21501600 DOI: 10.1016/j.bcp.2011.03.031] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Revised: 03/29/2011] [Accepted: 03/31/2011] [Indexed: 02/06/2023]
Abstract
It has become apparent of late that even in tamoxifen and/or aromatase resistant breast cancers, ERα remains a bona fide therapeutic target. Not surprisingly, therefore, there has been considerable interest in developing Selective ER Degraders (SERDs), compounds that target the receptor for degradation. Currently, ICI 182,780 (ICI, fulvestrant) is the only SERD approved for the treatment of breast cancer. However, the poor pharmaceutical properties of this injectable drug and its lack of superiority over second line aromatase inhibitors in late stage breast cancer have negatively impacted its clinical use. These findings have provided the impetus to develop second generation, orally bioavailable SERDs with which quantitative turnover of ERα in tumors can be achieved. Interestingly however, the contribution of SERD activity to fulvestrant efficacy is unclear, making it difficult to define the characteristics desired of the next generation of ER antagonists. It is of significance therefore, that we have determined that the antagonist activity of ICI and its ability to induce ERα degradation are not coupled processes. Specifically, our results indicate that it is the ability of ICI to interact with ERα and to (a) competitively displace estradiol and (b) induce a conformational change in ER incompatible with transcriptional activation that are likely to be the most important pharmacological characteristics of this drug. Collectively, these data argue for a renewed emphasis on the development of high affinity, orally bioavailable pure antagonists and suggest that SERD activity though proven effective may not be required for ERα antagonism in breast cancer.
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Affiliation(s)
- Suzanne E Wardell
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC 27710, USA.
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7
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Abstract
Both prolactin (PRL) and estrogen (E2) are involved in the pathogenesis and progression of mammary neoplasia, but the mechanisms by which these hormones interact to exert their effects in breast cancer cells are not well understood. We show here that PRL is able to activate the unliganded estrogen receptor (ER). In breast cancer cells, PRL activates a reporter plasmid containing estrogen response elements (EREs) and induces the ER target gene pS2. These actions are blocked by the antagonist ICI 182,780, showing that ER is required for the PRL-mediated effect. Moreover, PRL leads to phosphorylation of ERalpha in serine-118 (P-ERalpha), a modification related to the potentiation of ligand-independent transcriptional activation. In addition, PRL mimics the effect of E2 on target gene expression by inducing cyclical recruitment of ERalpha and P-ERalpha to ERE-containing promoters, resulting in recruitment of co-activators and acetylation of histone H3. Finally, PRL induces expression of c-Myc and Cyclin D1 and leads to increased cell proliferation, which is specifically antagonized by ICI 182,780 or ERalpha depletion. These results show that ligand-independent ERalpha activation appears to be an important component of the proliferative and transcriptional actions of PRL in breast cancer cells.
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8
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Scafonas A, Reszka AA, Kimmel DB, Hou XS, Su Q, Birzin ET, Kim S, Chen HY, Tan Q, Roher SP, Dininno F, Hammond ML, Rodan GA, Towler DA, Schmidt A. Agonist-like SERM effects on ERalpha-mediated repression of MMP1 promoter activity predict in vivo effects on bone and uterus. J Steroid Biochem Mol Biol 2008; 110:197-206. [PMID: 18508261 DOI: 10.1016/j.jsbmb.2007.10.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2006] [Accepted: 10/25/2007] [Indexed: 10/22/2022]
Abstract
Estradiol receptors (ER), ERalpha and ERbeta, are ligand-dependent transcription factors that regulate gene expression. Human and murine genetics suggest that ERalpha is the key target for estradiol action on bone, uterus and breast. To date, the molecular mode of action of estradiol and selective estradiol receptor modulators (SERMs) on bone is not fully understood. This is exemplified by a lack of in vitro assays that reliably predict SERM agonist activities in vivo. We hypothesized that ligand-dependent ERalpha transrepression, via protein-protein interactions at AP1, may predict estrogenic effects on bone. We modeled this using the MMP1 promoter, which encodes an AP1 binding site. We show that ICI-182780, raloxifene, 4-hydroxytamoxifen and estradiol all exhibit differential agonistic activities on the MMP1 promoter by suppressing activity by 20-80%. Transrepression efficacy and potency correlated with both uterotrophic (R(2)=0.98) and osteoprotective (R(2)=0.80) potential in the ovariectomized rat. This identifies MMP1 promoter transrepression as an agonist activity commonly shared by AF2 agonists and "antagonists" alike. Mutation analysis showed that the repression by estradiol and SERMs required correct amino acid sequences in the AF-2 domain. For instance, L540Q AF2 mutation did not alter responses to raloxifene, although it greatly increased responses to ICI-182780 (threefold) and reduced estradiol's effect by 20%. Furthermore, all tested ligands repressed the MMP1 promoter through the L540Q mutant with identical efficacy. Together, these data suggest that estradiol and SERMs share common agonist transcriptional activity via protein-protein interactions at AP1.
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Affiliation(s)
- Angela Scafonas
- Molecular Endocrinology, Merck Research Laboratories, West Point, 770 Sumneytown Pike, PA 19486, USA
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9
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Activation of estrogen receptor-alpha by E2 or EGF induces temporally distinct patterns of large-scale chromatin modification and mRNA transcription. PLoS One 2008; 3:e2286. [PMID: 18509470 PMCID: PMC2386239 DOI: 10.1371/journal.pone.0002286] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2007] [Accepted: 04/14/2008] [Indexed: 12/31/2022] Open
Abstract
Estrogen receptor-alpha (ER) transcription function is regulated in a ligand-dependent (e.g., estradiol, E2) or ligand-independent (e.g., growth factors) manner. Our laboratory seeks to understand these two modes of action. Using a cell line that contains a visible prolactin enhancer/promoter array (PRL-HeLa) regulated by ER, we analyzed ER response to E2 and EGF by quantifying image-based results. Data show differential recruitment of GFP-ER to the array, with the AF1 domain playing a vital role in EGF-mediated responsiveness. Temporal analyses of large-scale chromatin dynamics, and accumulation of array-localized reporter mRNA over 24 hours showed that the EGF response consists of a single pulse of reporter mRNA accumulation concomitant with transient increase in array decondensation. Estradiol induced a novel cyclical pattern of mRNA accumulation with a sustained increase in array decondensation. Collectively, our work shows that there is a stimuli-specific pattern of large-scale chromatin modification and transcript levels by ER.
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10
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Thomas RS, Sarwar N, Phoenix F, Coombes RC, Ali S. Phosphorylation at serines 104 and 106 by Erk1/2 MAPK is important for estrogen receptor-alpha activity. J Mol Endocrinol 2008; 40:173-84. [PMID: 18372406 PMCID: PMC2277492 DOI: 10.1677/jme-07-0165] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Phosphorylation of estrogen receptor-alpha (ERalpha) at specific residues in transcription activation function 1 (AF-1) can stimulate ERalpha activity in a ligand-independent manner. This has led to the proposal that AF-1 phosphorylation and the consequent increase in ERalpha activity could contribute to resistance to endocrine therapies in breast cancer patients. Previous studies have shown that serine 118 (S118) in AF-1 is phosphorylated by extracellular signal-regulated kinases 1 and 2 (Erk1/2) mitogen-activated protein kinase (MAPK) in a ligand-independent manner. Here, we show that serines 104 (S104) and 106 (S106) are also phosphorylated by MAPK in vitro and upon stimulation of MAPK activity in vivo. Phosphorylation of S104 and S106 can be inhibited by the MAP-erk kinase (MEK)1/2 inhibitor U0126 and by expression of kinase-dead Raf1. Further, we show that, although S118 is important for the stimulation of ERalpha activity by the selective ER modulator 4-hydroxytamoxifen (OHT), S104 and S106 are also required for the agonist activity of OHT. Acidic amino acid substitution of S104 or S106 stimulates ERalpha activity to a greater extent than the equivalent substitution at S118, suggesting that phosphorylation at S104 and S106 is important for ERalpha activity. Collectively, these data indicate that the MAPK stimulation of ERalpha activity involves the phosphorylation not only of S118 but also of S104 and S106, and that MAPK-mediated hyperphosphorylation of ERalpha at these sites may contribute to resistance to tamoxifen in breast cancer.
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Affiliation(s)
| | | | | | | | - Simak Ali
- (Correspondence should be addressed to S Ali; )
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11
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Development of ER-alpha and ER-beta expression in the developing ovine brain and pituitary. Gene Expr Patterns 2008; 8:457-463. [PMID: 18424193 DOI: 10.1016/j.gep.2008.03.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2007] [Revised: 03/02/2008] [Accepted: 03/06/2008] [Indexed: 11/22/2022]
Abstract
Fetal neuroendocrine development in late gestation is critical for maintenance of fetal homeostasis, growth, and readiness for birth. We designed the present study to identify the regional patterns of expression of the two main isoforms of the estrogen receptor, ER-alpha and ER-beta, in the developing ovine fetal brain. Fetal (80, 100, 120, 130, and 145 days gestation), neonatal (1 and 7 days), and adult sheep were euthanized and the following tissues were collected: pituitary, hypothalamus, hippocampus, cerebral cortex, and brainstem. Both ER's are expressed in the ovine brain as early as 80 days gestation, and the expression of both receptors appears to be developmentally regulated. We conclude that both forms of the estrogen receptor are expressed in fetal brain and pituitary throughout the latter half of gestation.
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12
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Eertmans F, Dhooge W, De Wever O, Bracke M, Comhaire F, Kaufman JM. Estrogen receptor alpha (ERalpha) and insulin-like growth factor I receptor (IGF-IR) cross-talk in the gonadotropic alphaT3-1 cell line. J Cell Physiol 2007; 212:583-90. [PMID: 17458895 DOI: 10.1002/jcp.21053] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
In reproductive tissues such as the breast and the uterus, cell proliferation and differentiation is strongly regulated by complex interactions between estrogen receptor alpha (ERalpha) and growth factor receptors. In the present study, we investigated the potential occurrence of such cross-talk in the murine, gonadotropic alphaT3-1 cell line, which expresses ERalpha and the IGF-I receptor (IGF-IR). Under estrogen-free conditions, basal cell proliferation and ER-mediated gene transcription was strongly inhibited by the selective estrogen receptor modulator (SERM) 4-hydroxy-tamoxifen (4-OH-Tam) and by the pure anti-estrogen ICI 182,780 (ICI). These effects can be reversed by either 17-beta-estradiol (E(2)) or insulin-like growth factor I (IGF-I), both exerting modest mitogenic effects in the alphaT3-1 cell line. Furthermore, IGF-I enhanced both basal and E(2)-induced ER-driven gene transcription. This may be explained, at least in part, by enhanced phosphorylation of ERalpha at serine 118, a prerequisite for the transactivation capacity of the receptor. Finally, the IGF-I-induced response on cell growth and ER-mediated transactivation can be inhibited with either ICI or 4-OH-Tam. In conclusion, our data indicate IGF-IR and ER interactions in the alphaT3-1 cell line, an in vitro model for the pituitary gonadotrophs, hereby suggesting a role of IGF-I in the regulation of gonadotropin synthesis and secretion.
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Affiliation(s)
- Frank Eertmans
- Department of Endocrinology, 6K12IE, Ghent University Hospital, De Pintelaan 185, Ghent, Belgium.
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Zheng A, Kallio A, Härkönen P. Tamoxifen-induced rapid death of MCF-7 breast cancer cells is mediated via extracellularly signal-regulated kinase signaling and can be abrogated by estrogen. Endocrinology 2007; 148:2764-77. [PMID: 17363451 DOI: 10.1210/en.2006-1269] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Tamoxifen (Tam) is widely used in chemotherapy of breast cancer. It inhibits proliferation and induces apoptosis of breast cancer cells by estrogen receptor (ER)-dependent modulation of gene expression. In addition, recent reports have shown that Tam also has nongenomic effects. We previously reported induction of a rapid mitochondrial death program in breast cancer cells at pharmacological concentrations of Tam. Here we studied the upstream signaling events leading to mitochondrial disruption by Tam. We observed that 5 mum Tam rapidly induced sustained activation of ERK1/2 in ER-positive breast cancer cell lines (MCF-7 and T47D) and that PD98059 (inhibitor of ERK activation) was able to protect MCF-7 cells against Tam-induced death. These data suggest that activation of ERK has a primary role in the acute death response of the cells. In addition, inhibition of epidermal growth factor receptor (EGFR) opposed both Tam-induced ERK1/2 phosphorylation and cell death, which suggests that EGFR-associated mechanisms are involved in Tam-induced death. ERK1/2 phosphorylation was associated with a prolonged nuclear localization of ERK1/2 as determined by fluorescence microscopy with ERK2-green fluorescent protein construct. 17beta-Estradiol was shown to exert a different kind of temporal pattern of ERK nuclear localization in comparison with Tam. Moreover, 17beta-estradiol was found to oppose the rapid effects of Tam in MCF-7 and T47D cells but not in MDA-MB-231 cells, which implies a role for estrogen receptors in the protective effect of estrogen. The pure antiestrogen ICI182780 could not, however, prevent Tam-induced ERK1/2 phosphorylation, suggesting that the Tam-induced rapid cell death is primarily ER-independent or mediated by ICI182780 insensitive nongenomic mechanisms.
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Affiliation(s)
- Aiping Zheng
- Institute of Biomedicine, Department of Anatomy, University of Turku, Tykistökatu 6A, 20520 Turku, Finland
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Timsit YE, Negishi M. CAR and PXR: the xenobiotic-sensing receptors. Steroids 2007; 72:231-46. [PMID: 17284330 PMCID: PMC1950246 DOI: 10.1016/j.steroids.2006.12.006] [Citation(s) in RCA: 311] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2006] [Revised: 12/07/2006] [Accepted: 12/11/2006] [Indexed: 01/13/2023]
Abstract
The xenobiotic receptors CAR and PXR constitute two important members of the NR1I nuclear receptor family. They function as sensors of toxic byproducts derived from endogenous metabolism and of exogenous chemicals, in order to enhance their elimination. This unique function of CAR and PXR sets them apart from the steroid hormone receptors. In contrast, the steroid receptors, exemplified by the estrogen receptor (ER) and glucocorticoid receptor (GR), are the sensors that tightly monitor and respond to changes in circulating steroid hormone levels to maintain body homeostasis. This divergence of the chemical- and steroid-sensing functions has evolved to ensure the fidelity of the steroid hormone endocrine regulation while allowing development of metabolic elimination pathways for xenobiotics. The development of the xenobiotic receptors CAR and PXR also reflect the increasing complexity of metabolism in higher organisms, which necessitate novel mechanisms for handling and eliminating metabolic by-products and foreign compounds from the body. The purpose of this review is to discuss similarities and differences between the xenobiotic receptors CAR and PXR with the prototypical steroid hormone receptors ER and GR. Interesting differences in structure explain in part the divergence in function and activation mechanisms of CAR/PXR from ER/GR. In addition, the physiological roles of CAR and PXR will be reviewed, with discussion of interactions of CAR and PXR with endocrine signaling pathways.
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Affiliation(s)
| | - Masahiko Negishi
- *CORRESPONDING AUTHOR ADDRESS: Dr, Masahiko Negishi, Ph.D., Head, Pharmacogenetics Section, Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, 111 T.W. Alexander Drive, Research Triangle Park, NC, 27709, Tel: (919) 541-2942, Fax (919) 541-0696,
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Wang Z, Chen W, Kono E, Dang T, Garabedian MJ. Modulation of glucocorticoid receptor phosphorylation and transcriptional activity by a C-terminal-associated protein phosphatase. Mol Endocrinol 2006; 21:625-34. [PMID: 17185395 DOI: 10.1210/me.2005-0338] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The glucocorticoid receptor (GR) is phosphorylated at three major sites on its N terminus (S203, S211, and S226), and phosphorylation modulates GR-regulatory functions in vivo. We examined the phosphorylation site interdependence, the contribution of the receptor C-terminal ligand-binding domain, and the participation of protein phosphatases in GR N-terminal phosphorylation and gene expression. We found that GR phosphorylation at S203 was greater when S226 was not phosphorylated and vice versa, indicative of intersite dependency. We also observed that a GR derivative lacking the ligand-binding domain, which no longer binds the heat shock protein 90 (Hsp90) complex, exhibits increased GR phosphorylation at all three sites as compared with the full-length receptor. A GR mutation (F602S) that produces a receptor less dependent on Hsp90 for function as well as treatment with the Hsp90 inhibitor geldanamycin also increased basal GR phosphorylation at a subset of sites. Pharmacological inhibition of serine/threonine protein phosphatases increased GR basal phosphorylation. Likewise, a reduction in protein phosphatase 5 protein levels enhanced GR phosphorylation at a subset of sites and selectively reduced the induction of endogenous GR target genes. Together, our findings suggest that GR undergoes a phosphorylation/dephosphorylation cycle that maintains steady-state receptor phosphorylation at a low basal level in the absence of ligand. Our findings also suggest that the ligand-dependent increase in GR phosphorylation results, in part, from the dissociation of a ligand-binding domain-linked protein phosphatase(s), and that changes in the intracellular concentration of protein phosphatase 5 differentially affect GR target gene expression.
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Affiliation(s)
- Zhen Wang
- Department of Microbiology, New York University Cancer Institute, New York University School of Medicine, 550 First Avenue, New York, New York 10016, USA
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