1
|
Patel A, Dhande R, Thakkar H. Development of intravaginal rod insert bearing liposomal raloxifene hydrochloride and Leuprolide acetate as a potential carrier for uterine targeting. J Pharm Pharmacol 2021; 73:653-663. [PMID: 33772288 DOI: 10.1093/jpp/rgab003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 01/26/2021] [Indexed: 01/16/2023]
Abstract
OBJECTIVES This project aimed at the formulation of dual drug entrapped liposomes held as freeze-dried intravaginal rod insert (IVR), to be administered by vaginal route for uterine targeting. METHODS Liposomes were formulated by dehydration-rehydration method using 3 : 1 molar ratio of1,2-distearoyl-sn-glycero-3-phosphocholine : Cholesterol. Characterization was done for vesicle size, zeta potential, entrapment efficiency, surface morphology and % loading. KEY FINDINGS Spherical and discrete vesicles of size 354 nm were observed in transmission electron microscopy (TEM) image. The entrapment efficiency of 90.91% and 74.3% w/w was obtained for Raloxifene Hydrochloride (RLX) and Leuprolide acetate (LA) respectively. Drug release was sustained for 6 days. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay results showed that dual drug entrapped liposomal formulation show significant cytotoxicity, as also confirmed by higher apoptosis in cell cycle analysis and apoptosis studies (FACS) analysis. Pharmacodynamic studies in New Zealand white female rabbits revealed that intravaginal administration of RLX-LA entrapped liposomal formulation shows considerable fibroid regression. CONCLUSIONS Uterine targeting of liposomal RLX-LA suggests its potential to solve the limitations of the presently available therapeutic options.
Collapse
Affiliation(s)
- Arpita Patel
- Shri G.H. Patel Pharmacy Building, Centre for Postgraduate Studies in Pharmacy, TIFAC Core in NDDS, Donor's Plaza, Fatehgunj, Vadodara, India
| | - Rahul Dhande
- Shri G.H. Patel Pharmacy Building, Centre for Postgraduate Studies in Pharmacy, TIFAC Core in NDDS, Donor's Plaza, Fatehgunj, Vadodara, India
| | - Hetal Thakkar
- Shri G.H. Patel Pharmacy Building, Centre for Postgraduate Studies in Pharmacy, TIFAC Core in NDDS, Donor's Plaza, Fatehgunj, Vadodara, India
| |
Collapse
|
2
|
Katiki MR, Kommula D, Polepalli S, Jain N, Murty MSR. A One-pot Multicomponent ‘Click’ Approach to the Synthesis of Novel Tamoxifen-triazole Conjugates using Nano Iron Oxide Catalyst and their Preliminary Antiproliferative Activity Studies. LETT DRUG DES DISCOV 2019. [DOI: 10.2174/1570180815666180621100314] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Background:
In an effort to establish new drug candidates with improved antiproliferative
activity, we report here a novel class of compounds designed rationally by the replacement of
an ethyl group in tamoxifen with a methylene (1H-1,2,4-triazole) and the introduction of 1,4-
substituted 1,2,3-triazoles in the basic side chain.
Methods:
Magnetically separable iron oxide nanoparticles have been found to effectively catalyze
the one-pot multicomponent click synthesis of 1,4-disubstituted 1,2,3-triazole conjugates in water.
IR, 1HNMR, 13CNMR and HRMS experiments have been implemented for the unmistakable determination
of the regiochemistry of the process. The novel compounds were evaluated for their antiproliferative
activity against four human tumor cell lines, namely, MCF-7, MDA-MB-231, HeLa,
and A549. Cell growth inhibition was assessed according to the standard Sulforhodamine B (SRB)
cell proliferation method.
Results:
The most active compounds 4h, 4n and 5a have been identified with superior GI50 values
in the range of 0.13–0.31 µM as compared with the reference drug, tamoxifen (0.25-0.72 µM).
Conclusion:
Additionally, taking the stereochemistry into consideration, E isomers seem slightly
more active towards the tested cancer cell lines with respect to Z isomers.
Collapse
Affiliation(s)
- Mohana Rao Katiki
- Medicinal Chemistry & Pharmacology Division, Discovery Laboratory, CSIR–Indian Institute of Chemical Technology, Hyderabad-500 007, India
| | - Dileep Kommula
- Medicinal Chemistry & Pharmacology Division, Discovery Laboratory, CSIR–Indian Institute of Chemical Technology, Hyderabad-500 007, India
| | - Sowjanya Polepalli
- Centre for Chemical Biology, CSIR–Indian Institute of Chemical Technology, Hyderabad- 500 007, India
| | - Nishant Jain
- Centre for Chemical Biology, CSIR–Indian Institute of Chemical Technology, Hyderabad- 500 007, India
| | - Madugula Sree Rama Murty
- Medicinal Chemistry & Pharmacology Division, Discovery Laboratory, CSIR–Indian Institute of Chemical Technology, Hyderabad-500 007, India
| |
Collapse
|
3
|
Low-dose tamoxifen treatment in juvenile males has long-term adverse effects on the reproductive system: implications for inducible transgenics. Sci Rep 2017; 7:8991. [PMID: 28827578 PMCID: PMC5566418 DOI: 10.1038/s41598-017-09016-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 07/17/2017] [Indexed: 11/08/2022] Open
Abstract
The tamoxifen-inducible Cre system is a popular transgenic method for controlling the induction of recombination by Cre at a specific time and in a specific cell type. However, tamoxifen is not an inert inducer of recombination, but an established endocrine disruptor with mixed agonist/antagonist activity acting via endogenous estrogen receptors. Such potentially confounding effects should be controlled for, but >40% of publications that have used tamoxifen to generate conditional knockouts have not reported even the minimum appropriate controls. To highlight the importance of this issue, the present study investigated the long-term impacts of different doses of a single systemic tamoxifen injection on the testis and the wider endocrine system. We found that a single dose of tamoxifen less than 10% of the mean dose used for recombination induction, caused adverse effects to the testis and to the reproductive endocrine system that persisted long-term. These data raise significant concerns about the widespread use of tamoxifen induction of recombination, and highlight the importance of including appropriate controls in all pathophysiological studies using this means of induction.
Collapse
|
4
|
Chakraborty S, Asare BK, Biswas PK, Rajnarayanan RV. Designer interface peptide grafts target estrogen receptor alpha dimerization. Biochem Biophys Res Commun 2016; 478:116-122. [PMID: 27462021 PMCID: PMC5214063 DOI: 10.1016/j.bbrc.2016.07.083] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2016] [Accepted: 07/19/2016] [Indexed: 11/15/2022]
Abstract
The nuclear transcription factor estrogen receptor alpha (ERα), triggered by its cognate ligand estrogen, regulates a variety of cellular signaling events. ERα is expressed in 70% of breast cancers and is a widely validated target for anti-breast cancer drug discovery. Administration of anti-estrogen to block estrogen receptor activation is still a viable anti-breast cancer treatment option but anti-estrogen resistance has been a significant bottle-neck. Dimerization of estrogen receptor is required for ER activation. Blocking ERα dimerization is therefore a complementary and alternative strategy to combat anti-estrogen resistance. Dimer interface peptide "I-box" derived from ER residues 503-518 specifically blocks ER dimerization. Recently using a comprehensive molecular simulation we studied the interaction dynamics of ERα LBDs in a homo-dimer. Based on this study, we identified three interface recognition peptide motifs LDKITDT (ERα residues 479-485), LQQQHQRLAQ (residues 497-506), and LSHIRHMSNK (residues 511-520) and reported the suitability of using LQQQHQRLAQ (ER 497-506) as a template to design inhibitors of ERα dimerization. Stability and self-aggregation of peptide based therapeutics poses a significant bottle-neck to proceed further. In this study utilizing peptide grafted to preserve their pharmacophoric recognition motif and assessed their stability and potential to block ERα mediated activity in silico and in vitro. The Grafted peptides blocked ERα mediated cell proliferation and viability of breast cancer cells but did not alter their apoptotic fate. We believe the structural clues identified in this study can be used to identify novel peptidometics and small molecules that specifically target ER dimer interface generating a new breed of anti-cancer agents.
Collapse
Affiliation(s)
- S Chakraborty
- Laboratory of Computational Biophysics & Bioengineering, Department of Physics, Tougaloo College, Tougaloo, MS 39174, United States
| | - B K Asare
- Department of Pharmacology and Toxicology, University of Buffalo, Buffalo, NY 14214, United States
| | - P K Biswas
- Laboratory of Computational Biophysics & Bioengineering, Department of Physics, Tougaloo College, Tougaloo, MS 39174, United States.
| | - R V Rajnarayanan
- Department of Pharmacology and Toxicology, University of Buffalo, Buffalo, NY 14214, United States.
| |
Collapse
|
5
|
Fan P, Maximov PY, Curpan RF, Abderrahman B, Jordan VC. The molecular, cellular and clinical consequences of targeting the estrogen receptor following estrogen deprivation therapy. Mol Cell Endocrinol 2015; 418 Pt 3:245-63. [PMID: 26052034 PMCID: PMC4760743 DOI: 10.1016/j.mce.2015.06.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 05/20/2015] [Accepted: 06/01/2015] [Indexed: 01/04/2023]
Abstract
During the past 20 years our understanding of the control of breast tumor development, growth and survival has changed dramatically. The once long forgotten application of high dose synthetic estrogen therapy as the first chemical therapy to treat any cancer has been resurrected, refined and reinvented as the new biology of estrogen-induced apoptosis. High dose estrogen therapy was cast aside once tamoxifen, from its origins as a failed "morning after pill", was reinvented as the first targeted therapy to treat any cancer. The current understanding of the mechanism of estrogen-induced apoptosis is described as a consequence of acquired resistance to long term antihormone therapy in estrogen receptor (ER) positive breast cancer. The ER signal transduction pathway remains a target for therapy in breast cancer despite "antiestrogen" resistance, but becomes a regulator of resistance. Multiple mechanisms of resistance come into play: Selective ER modulator (SERM) stimulated growth, growth factor/ER crosstalk, estrogen-induced apoptosis and mutations of ER. But it is with the science of estrogen-induced apoptosis that the next innovation in women's health will be developed. Recent evidence suggests that the glucocorticoid properties of medroxyprogesterone acetate blunt estrogen-induced apoptosis in estrogen deprived breast cancer cell populations. As a result breast cancer develops during long-term hormone replacement therapy (HRT). A new synthetic progestin with estrogen-like properties, such as the 19 nortestosterone derivatives used in oral contraceptives, will continue to protect the uterus from unopposed estrogen stimulation but at the same time, reinforce apoptosis in vulnerable populations of nascent breast cancer cells.
Collapse
Affiliation(s)
- Ping Fan
- Department of Breast Medical Oncology, MD Anderson Cancer Center, Houston, TX, USA
| | - Philipp Y Maximov
- Department of Breast Medical Oncology, MD Anderson Cancer Center, Houston, TX, USA
| | - Ramona F Curpan
- Institute of Chemistry, Romanian Academy, Timisoara, Romania
| | | | - V Craig Jordan
- Department of Breast Medical Oncology, MD Anderson Cancer Center, Houston, TX, USA.
| |
Collapse
|
6
|
Jordan VC, Curpan R, Maximov PY. Estrogen receptor mutations found in breast cancer metastases integrated with the molecular pharmacology of selective ER modulators. J Natl Cancer Inst 2015; 107:djv075. [PMID: 25838462 DOI: 10.1093/jnci/djv075] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Accepted: 02/24/2015] [Indexed: 01/11/2023] Open
Abstract
The consistent reports of mutations at Asp538 and Tyr537 in helix 12 of the ligand-binding domain (LBD) of estrogen receptors (ERs) from antihormone-resistant breast cancer metastases constitute an important advance. The mutant amino acids interact with an anchor amino acid, Asp351, to close the LBD, thereby creating a ligand-free constitutively activated ER. Amino acids Asp 538, Tyr 537, and Asp 351 are known to play a role in either the turnover of ER, the antiestrogenic activity of the ER complex, or the estrogen-like actions of selective ER modulators. A unifying mechanism of action for these amino acids to enhance ER gene activation and growth response is presented. There is a range of mutations described in metastases vs low to zero in primary disease, so the new knowledge is of clinical relevance, thereby confirming an additional mechanism of acquired resistance to antihormone therapy through cell population selection pressure and enrichment during treatment. Circulating tumor cells containing ER mutations can be cultured ex vivo, and tumor tissues can be grown as patient-derived xenografts to add a new dimension for testing drug susceptibility for future drug discovery.
Collapse
Affiliation(s)
- V Craig Jordan
- MD Anderson Cancer Center, Department of Breast Medical Oncology, Houston, TX (VCJ, PYM); Institute of Chemistry, Romanian Academy, Timisoara, Romania (RC).
| | - Ramona Curpan
- MD Anderson Cancer Center, Department of Breast Medical Oncology, Houston, TX (VCJ, PYM); Institute of Chemistry, Romanian Academy, Timisoara, Romania (RC)
| | - Philipp Y Maximov
- MD Anderson Cancer Center, Department of Breast Medical Oncology, Houston, TX (VCJ, PYM); Institute of Chemistry, Romanian Academy, Timisoara, Romania (RC)
| |
Collapse
|
7
|
Chakraborty S, Levenson AS, Biswas PK. Structural insights into Resveratrol's antagonist and partial agonist actions on estrogen receptor alpha. BMC STRUCTURAL BIOLOGY 2013; 13:27. [PMID: 24160181 PMCID: PMC4015837 DOI: 10.1186/1472-6807-13-27] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 09/18/2013] [Indexed: 01/20/2023]
Abstract
BACKGROUND Resveratrol, a naturally occurring stilbene, has been categorized as a phytoestrogen due to its ability to compete with natural estrogens for binding to estrogen receptor alpha (ERα) and modulate the biological responses exerted by the receptor. Biological effects of resveratrol (RES) on estrogen receptor alpha (ERα) remain highly controversial, since both estrogenic and anti-estrogenic properties were observed. RESULTS Here, we provide insight into the structural basis of the agonist/antagonist effects of RES on ERα ligand binding domain (LBD). Using atomistic simulation, we found that RES bound ERα monomer in antagonist conformation, where Helix 12 moves away from the ligand pocket and orients into the co-activator binding groove of LBD, is more stable than RES bound ERα in agonist conformation, where Helix 12 lays over the ligand binding pocket. Upon dimerization, the agonistic conformation of RES-ERα dimer becomes more stable compared to the corresponding monomer but still remains less stable compared to the corresponding dimer in antagonist conformation. Interestingly, while the binding pocket and the binding contacts of RES to ERα are similar to those of pure agonist diethylstilbestrol (DES), the binding energy is much less and the hydrogen bonding contacts also differ providing clues for the partial agonistic character of RES on ERα. CONCLUSIONS Our Molecular Dynamics simulation of RES-ERα structures with agonist and antagonist orientations of Helix 12 suggests RES action is more similar to Selective Estrogen Receptor Modulator (SERM) opening up the importance of cellular environment and active roles of co-regulator proteins in a given system. Our study reveals that potential co-activators must compete with the Helix 12 and displace it away from the activator binding groove to enhance the agonistic activity.
Collapse
Affiliation(s)
- Sandipan Chakraborty
- Laboratory of Computational Biophysics & Bioengineering, Department of Physics, Tougaloo College, 500 West County Line Road, Toogaloo, MS 39174, USA
- Saroj Mohan Institute of Technology, Hooghly, West Bengal 712512, India
| | - Anait S Levenson
- Cancer Institute and Department of Pathology, University of Mississippi Medical Center, Jackson, MS 39202, USA
| | - Pradip K Biswas
- Laboratory of Computational Biophysics & Bioengineering, Department of Physics, Tougaloo College, 500 West County Line Road, Toogaloo, MS 39174, USA
| |
Collapse
|
8
|
Abstract
This review will discuss the concept of reproductive aging, which includes the definition of menopause, its symptoms, and predisposing conditions. It will elaborate upon the contributory factors implicated in the pathogenesis of menopause, focusing most prominently on oxidative stress. Specifically, this paper will explain how oxidative stress, in the form of free radicals and antioxidant deficiencies, has been directly linked to the decline of estrogen during reproductive aging. Additionally, this paper will elaborate upon the treatment options aimed at mitigating the menopausal symptoms and hormonal deficiencies that can lead to various disease processes. Treatment options such as hormonal therapy, antioxidant supplementation, and lifestyle modification have been explored for their effectiveness in treating and preventing the symptoms and sequelae of menopause. The majority of information in this review was obtained through PubMed and the National Library of Medicine. While most references in this paper are original research articles, a limited number of references are comprehensive reviews on the topic.
Collapse
Affiliation(s)
- Sejal B. Doshi
- Department of Andrology, Center for Reproductive Medicine, Cleveland Clinic, Cleveland, Ohio, USA
| | - Ashok Agarwal
- Department of Andrology, Center for Reproductive Medicine, Cleveland Clinic, Cleveland, Ohio, USA
| |
Collapse
|
9
|
Yang G, Nowsheen S, Aziz K, Georgakilas AG. Toxicity and adverse effects of Tamoxifen and other anti-estrogen drugs. Pharmacol Ther 2013; 139:392-404. [PMID: 23711794 DOI: 10.1016/j.pharmthera.2013.05.005] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 05/13/2013] [Indexed: 01/20/2023]
Abstract
Breast cancer is a heterogeneous disease affecting thousands of people every year. Multiple factors are responsible in causing breast cancer while a number of treatment options are also available for the disease. Tamoxifen is the most widely used anti-estrogen for the treatment of hormone-dependent breast cancer. The specific drug is used as a hormonal therapy for patients who exhibit estrogen receptor positive breast cancer. The pharmacological activity of Tamoxifen is dependent on its conversion to its active metabolite, endoxifen, by CYP2D6. Tamoxifen reduces the risk of recurrence and death from breast cancer when given as adjuvant therapy and provides effective palliation for patients with metastatic breast cancer. In this review we focus on the role of Tamoxifen in breast cancer treatment including mechanisms and side-effects. Finally, we discuss in detail the exciting prospects that lie ahead.
Collapse
Affiliation(s)
- Geniey Yang
- Department of Biology, Thomas Harriot College of Arts and Sciences, East Carolina University, Greenville, NC 27858, USA
| | | | | | | |
Collapse
|
10
|
Newcomb PA, Kampman E, Trentham-Dietz A, Egan KM, Titus LJ, Baron JA, Hampton JM, Passarelli MN, Willett WC. Alcohol consumption before and after breast cancer diagnosis: associations with survival from breast cancer, cardiovascular disease, and other causes. J Clin Oncol 2013; 31:1939-46. [PMID: 23569314 DOI: 10.1200/jco.2012.46.5765] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
PURPOSE Alcohol intake is associated with increased risk of breast cancer. In contrast, the relation between alcohol consumption and breast cancer survival is less clear. PATIENTS AND METHODS We assessed pre- and postdiagnostic alcohol intake in a cohort of 22,890 women with incident invasive breast cancer who were residents of Wisconsin, Massachusetts, or New Hampshire and diagnosed from 198 to 200 at ages 20 to 79 years. All women reported on prediagnostic intake; a subsample of 4,881 reported on postdiagnostic intake. RESULTS During a median follow-up of 11.3 years from diagnosis, 7,780 deaths occurred, including 3,484 resulting from breast cancer. Hazard ratios (HR) and 95% CIs were estimated. Based on a quadratic analysis, moderate alcohol consumption before diagnosis was modestly associated with disease-specific survival (compared with nondrinkers, HR = 0.93 [95% CI, 0.85 to 1.02], 0.85 [95% CI, 0.75 to 0.95], 0.88 [95% CI, 0.75 to 1.02], and 0.89 [95% CI, 0.77 to 1.04] for two or more, three to six, seven to nine, and ≥ 10 drinks/wk, respectively). Alcohol consumption after diagnosis was not associated with disease-specific survival (compared with nondrinkers, HR = 0.88 [95% CI, 0.61 to 1.27], 0.80 [95% CI, 0.49 to 1.32], 1.01 [95% CI, 0.55 to 1.87], and 0.83 [95% CI, 0.45 to 1.54] for two or more, three to six, seven to nine, and ≥ 10 drinks/wk, respectively). Results did not vary by beverage type. Women consuming moderate levels of alcohol, either before or after diagnosis, experienced better cardiovascular and overall survival than nondrinkers. CONCLUSION Overall alcohol consumption before diagnosis was not associated with disease-specific survival, but we found a suggestion favoring moderate consumption. There was no evidence for an association with postdiagnosis alcohol intake and breast cancer survival. This study, however, does provide support for a benefit of limited alcohol intake for cardiovascular and overall survival in women with breast cancer.
Collapse
Affiliation(s)
- Polly A Newcomb
- Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
11
|
In silico design of peptidic inhibitors targeting estrogen receptor alpha dimer interface. Mol Divers 2012; 16:441-51. [PMID: 22752657 DOI: 10.1007/s11030-012-9378-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 05/28/2012] [Indexed: 10/28/2022]
Abstract
Human estrogen receptor alpha (ERα), which acts as a biomarker and as a therapeutic target for breast cancers, is activated by agonist ligands and co-activator proteins. Selective estrogen receptor modulators (SERM) act as antagonists in specific tissues and tamoxifen, a SERM, has served as a drug for decades for ERα-positive breast cancers. However, the ligand-selective and tissue-specific response of ERα biological activity and the resistance to tamoxifen treatment in advanced stages of ERα-positive breast cancers underscores the need to find a ligand-independent inhibitor for ERα. Here we present a ligand-independent approach of inhibiting ERα transactivation targeting its dimerization-a key process of ERα biological activity. Using in silico techniques, we first elucidated the hydrogen bond interactions involved in dimerization and identified three interfacial sequence motifs, where sequence I (DKITD) and sequence II (QQQHQRLAQ) of one monomer form hydrogen bonding with sequence II and sequence I of the second monomer, respectively, and sequence III (LSHIRHMSNK) hydrogen bonds with the same from the second monomer. Studying the structural stability and the binding affinity of the peptides derived from these sequence motifs, we found that an extended and ARG mutated version (LQQQHQQLAQ) of sequence II can act as a suitable template for designing peptidic inhibitors. It provides additional structural stability and interacts more strongly with ERα dimer interface groove formed by helices 9 and 10/11 and prevent ERα dimerization. Our result provides a novel therapeutic designing pipeline for ligand-independent inhibition of ERα.
Collapse
|
12
|
Sun L, Shao X, Hu X, Chi J, Jin Y, Ye W, Fu Z. Transcriptional responses in Japanese medaka (Oryzias latipes) exposed to binary mixtures of an estrogen and anti-estrogens. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2011; 105:629-639. [PMID: 21963593 DOI: 10.1016/j.aquatox.2011.08.024] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Revised: 08/23/2011] [Accepted: 08/26/2011] [Indexed: 05/31/2023]
Abstract
Determining ecotoxicological risks of exposure to mixtures of endocrine disrupting chemicals (EDCs) remains a daunting challenge in environmental toxicology. Recently, some studies have illustrated that transcriptional profiling of genes offers the potential to identify the chemical causation of effects that are induced by exposure to complex mixtures. In the present study, the transcriptional responses of a set of genes involved in the hypothalamic-pituitary-gonadal (HPG, or HPG[L]-liver) axis of Japanese medaka (Oryzias latipes) were systematically examined after treatment with a combination of an estrogen (17α-ethinylestradiol [EE2], 20 ng/L) and two model anti-estrogens, the aromatase inhibitor (AI) letrozole (LET) and the selective estrogen-receptor modulator (SERM) tamoxifen (TAM), at three concentrations (30, 100 and 300 μg/L) for 72 h. The data presented demonstrate that although gene transcription analyses increase our mechanistic understanding of the modes of action (MOAs) of EDCs, the characteristic of most genes altered by a certain single chemical exposure may not be useful for diagnostic chemical causation in a mixture exposure situation. For example, the induction of one vitellogenin gene (VTG1) transcription caused by EE2 in male fish was effectively blocked after exposure to a combination of EE2 and LET but not EE2 and TAM. Moreover, the responses in gene transcription to coexposure were elicited partially in a nonmonotonic concentration-dependent manner. Therefore, the application of transcriptional profiling of genes for screening complex environmental samples should be further evaluated until biomarker gene responses are robust and sensitive enough to properly assess the complex interactions.
Collapse
Affiliation(s)
- Liwei Sun
- College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou 310032, PR China
| | | | | | | | | | | | | |
Collapse
|
13
|
The exonuclease activity of hPMC2 is required for transcriptional regulation of the QR gene and repair of estrogen-induced abasic sites. Oncogene 2011; 30:4731-9. [PMID: 21602889 PMCID: PMC3161170 DOI: 10.1038/onc.2011.186] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
We have previously reported that the expression of antioxidative stress enzymes are upregulated by trans-hydroxytamoxifen (TOT) in breast epithelial cell lines providing protection against estrogen-induced DNA damage. This regulation involves Estrogen Receptor beta (ERβ) recruitment to the Electrophile Response Element (EpRE) and a novel protein, human homolog of Xenopus gene which Prevents Mitotic Catastrophe (hPMC2). We have also demonstrated that ERβ and hPMC2 are required for TOT-dependent recruitment of poly (ADP-ribose) polymerase 1 (PARP-1) and Topoisomerase IIβ (Topo IIβ) to the EpRE. Sequence analysis reveals that the C-terminus of hPMC2 encodes a putative exonuclease domain. Using in vitro kinetic assays, we found that hPMC2 is a 3'–5' non-processive exonuclease that degrades both single stranded and double stranded substrates. Mutation of two conserved carboxylate residues drastically reduced the exonuclease activity of hPMC2 indicating the relative importance of the catalytic residues. Western blot analysis of breast cancer cell lines for Quinone Reductase (QR) levels revealed that the intrinsic exonuclease activity of hPMC2 was required for TOT-induced QR upregulation. Chromatin immunoprecipitation assays (ChIP) also indicated that hPMC2 was involved in the formation of strand breaks observed with TOT-treatment and is specific for the EpRE-containing region of the QR gene. We also determined that the transcription factor NF-E2-related factor-2 (Nrf2) is involved in the specificity of hPMC2 for the EpRE. In addition, we determined that the catalytic activity of hPMC2 is required for repair of abasic sites that result from estrogen-induced DNA damage. Thus our study provides a mechanistic basis for transcriptional regulation by hPMC2 and provides novel insights into its role in cancer prevention.
Collapse
|
14
|
Jain R, Vikas, Radhapyari K. Voltammetric quantification of tamoxifen. Drug Test Anal 2011; 3:743-7. [DOI: 10.1002/dta.240] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 11/03/2010] [Accepted: 11/03/2010] [Indexed: 11/09/2022]
|
15
|
Abstract
Several lines of evidence attest to the existence of alternative ligand binding sites on the oestrogen receptor (ER), including non-competitive inhibition by trilostane or tamoxifen. It is possible that the inhibitory action of conventional oestrogen agonists at high concentrations may indicate that they too interact at alternative ER sites, albeit at low affinity. To test this possibility an oestrogen reporter assay was used to compare the activity of different oestrogens and antagonists in breast cancer and prostate cell lines. All four cell lines tested contained different amounts of oestrogen receptor α (ERα), ERβ, progesterone receptor and coregulator mRNA. Though differences were observed in response to stimulation and inhibition, these correlated only with the presence or absence of ERα, and not with the other components. Thus stimulation of the reporter by oestradiol and oestrone was biphasic in the breast cancer cells, while prostate cells were unable to respond. Only T47D cells were stimulated by oestriol or diethylstilboestrol, however reporter activity of all the cell lines was repressed by 10μM diethylstilboestrol. Reporter activity of MCF-7 cells was inhibited by tamoxifen, raloxifene and ICI 182,780, but stimulated by trilostane, yet all these antioestrogens inhibited agonist-stimulated activity. Trilostane also inhibited the agonism seen in cells co-treated with E2 and tamoxifen. It is clear that several of the compounds tested may have either agonist or antagonist effects under different conditions and at different concentrations, acting through ERα alone. Though biphasic dose response curves, or hormesis, have been attributed to various mechanisms, we here provide evidence that alternative ligand binding sites may contribute to this phenomenon.
Collapse
|
16
|
Cyrus K, Wehenkel M, Choi EY, Lee H, Swanson H, Kim KB. Jostling for position: optimizing linker location in the design of estrogen receptor-targeting PROTACs. ChemMedChem 2010; 5:979-85. [PMID: 20512796 PMCID: PMC3516907 DOI: 10.1002/cmdc.201000146] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Indexed: 01/25/2023]
Abstract
Estrogen receptor-alpha (ER) antagonists have been widely used for breast cancer therapy. Despite initial responsiveness, hormone-sensitive ER-positive cancer cells eventually develop resistance to ER antagonists. It has been shown that in most of these resistant tumor cells, the ER is expressed and continues to regulate tumor growth. Recent studies indicate that tamoxifen initially acts as an antagonist, but later functions as an ER agonist, promoting tumor growth. This suggests that targeted ER degradation may provide an effective therapeutic approach for breast cancers, even those that are resistant to conventional therapies. With this in mind, we previously demonstrated that proteolysis targeting chimeras (PROTACs) effectively induce degradation of the ER as a proof-of-concept experiment. Herein we further refined the PROTAC approach to target the ER for degradation. The ER-targeting PROTACs are composed of an estradiol on one end and a hypoxia-inducing factor 1alpha (HIF-1alpha)-derived synthetic pentapeptide on the other. The pentapeptide is recognized by an E3 ubiquitin ligase called the von Hippel Lindau tumor suppressor protein (pVHL), thereby recruiting the ER to this E3 ligase for ubiquitination and degradation. Specifically, the pentapeptide is attached at three different locations on estradiol to generate three different PROTAC types. With the pentapeptide linked through the C7alpha position of estradiol, the resulting PROTAC shows the most effective ER degradation and highest affinity for the estrogen receptor. This result provides an opportunity to develop a novel type of ER antagonist that may overcome the resistance of breast tumors to conventional drugs such as tamoxifen and fulvestrant (Faslodex).
Collapse
Affiliation(s)
- Kedra Cyrus
- Department of Pharmaceutical Sciences, University of Kentucky, 789 South Limestone, Lexington, KY 40536-0596, USA, Fax: (+1)859-257-7564
| | - Marie Wehenkel
- Department of Pharmaceutical Sciences, University of Kentucky, 789 South Limestone, Lexington, KY 40536-0596, USA, Fax: (+1)859-257-7564
| | - Eun-Young Choi
- Department of Molecular and Biomedical Pharmacology, University of Kentucky, 800 Rose Street, Lexington, KY 40536, USA
| | - Hyosung Lee
- Department of Pharmaceutical Sciences, University of Kentucky, 789 South Limestone, Lexington, KY 40536-0596, USA, Fax: (+1)859-257-7564
| | - Hollie Swanson
- Department of Molecular and Biomedical Pharmacology, University of Kentucky, 800 Rose Street, Lexington, KY 40536, USA
| | - Kyung-Bo Kim
- Department of Pharmaceutical Sciences, University of Kentucky, 789 South Limestone, Lexington, KY 40536-0596, USA, Fax: (+1)859-257-7564
| |
Collapse
|
17
|
Hubbell AP, Murray L, Liu W, Witte K. Looking toward the future of clinical trials: The application of communication variables to the recruitment of women into breast cancer clinical trials. ACTA ACUST UNITED AC 2010. [DOI: 10.1080/02604027.2001.9972851] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
18
|
Taylor CK, Levy RM, Elliott JC, Burnett BP. The effect of genistein aglycone on cancer and cancer risk: a review of in vitro, preclinical, and clinical studies. Nutr Rev 2009; 67:398-415. [PMID: 19566600 DOI: 10.1111/j.1753-4887.2009.00213.x] [Citation(s) in RCA: 127] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In Asian epidemiological studies, health benefits, including reduced incidence of breast and prostate cancers, are attributed to soy food and isoflavone consumption. The recent increased intake of soy foods and supplements in the American diet has raised concerns about the possible estrogen-like effects of natural isoflavones and possible promotion or propagation of estrogen-sensitive cancers. These concerns are primarily based on in vitro and rodent data which suggest that genistein aglycone can stimulate tumor cell proliferation and growth in mice having deficient immune systems. In contrast, a recent nested case-control study and meta-analysis of numerous epidemiological studies show an inverse correlation between genistein intake and breast cancer risk. Furthermore, clinical studies in osteopenic and osteoporotic, postmenopausal women support the breast and uterine safety of purified naturally derived genistein administered for up to 3 years. In this review, we summarize the in vitro, preclinical and clinical evidence for the safety of natural genistein.
Collapse
|
19
|
Conde SJ, Luvizotto RAM, Síbio MT, Katayama MLH, Brentani MM, Nogueira CR. Tamoxifen inhibits transforming growth factor-alpha gene expression in human breast carcinoma samples treated with triiodothyronine. J Endocrinol Invest 2008; 31:1047-51. [PMID: 19246968 DOI: 10.1007/bf03345650] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECTIVES To examine the effects of triiodothyronine (T3), 17beta-estradiol (E2), and tamoxifen (TAM) on transforming growth factor (TGF)-alpha gene expression in primary breast cancer cell cultures and interactions between the different treatments. METHODS AND RESULTS Patients included in the study (no.=12) had been newly diagnosed with breast cancer. Fresh human breast carcinoma tissue was cut into 0.3- mm slices. These slices were placed in six 35-mm dishes on 2-ml organ culture medium. Dishes received the following treatments: dish 1: ethanol; dish 2: T3; dish 3: T3+TAM; dish 4: TAM; dish 5: E2; dish 6: E2+TAM. TGF-alpha mRNA content was normalized to glyceraldehyde-3-phosphate dehydrogenase mRNA levels. All tissues included in this study were positive for estrogen receptor (ER) and thyroid hormone receptor expression. Treatment with T3 for 48 h significantly increased TGF-alpha mRNA levels compared to controls (15-fold), and concomitant treatment with TAM reduced expression to 3.4-fold compared to controls. When only TAM was added to the culture medium, TGF-alpha mRNA expression increased 5.3-fold, significantly higher than with all other treatment modalities. CONCLUSION We demonstrate that TGF-alpha mRNA expression is more efficiently upregulated by T3 than E2. Concomitant treatment with TAM had a mitigating effect on the T3 effect, while E2 induced TGF-alpha upregulation. Our findings show some similarities between primary culture and breast cancer cell lines, but also some important differences: a) induction of TGF-alpha, a mitogenic protein, by TAM; b) a differential effect of TAM that may depend on relative expression of ER alpha and beta; and c) supraphysiological doses of T3 may induce mitogenic signals in breast cancer tissue under conditions of low circulating E2.
Collapse
Affiliation(s)
- S J Conde
- Division of Endocrinology and Metabolism, Department of Medical Clinic, UNESP, Botucatu, Brazil
| | | | | | | | | | | |
Collapse
|
20
|
Buriez O, Heldt JM, Labbé E, Vessières A, Jaouen G, Amatore C. Reactivity and Antiproliferative Activity of Ferrocenyl-Tamoxifen Adducts with Cyclodextrins against Hormone-Independent Breast-Cancer Cell Lines. Chemistry 2008; 14:8195-203. [DOI: 10.1002/chem.200800507] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
21
|
Greenspan JD, Craft RM, LeResche L, Arendt-Nielsen L, Berkley KJ, Fillingim RB, Gold MS, Holdcroft A, Lautenbacher S, Mayer EA, Mogil JS, Murphy AZ, Traub RJ. Studying sex and gender differences in pain and analgesia: a consensus report. Pain 2007; 132 Suppl 1:S26-S45. [PMID: 17964077 DOI: 10.1016/j.pain.2007.10.014] [Citation(s) in RCA: 700] [Impact Index Per Article: 41.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Accepted: 10/09/2007] [Indexed: 12/21/2022]
Abstract
In September 2006, members of the Sex, Gender and Pain Special Interest Group of the International Association for the Study of Pain met to discuss the following: (1) what is known about sex and gender differences in pain and analgesia; (2) what are the "best practice" guidelines for pain research with respect to sex and gender; and (3) what are the crucial questions to address in the near future? The resulting consensus presented herein includes input from basic science, clinical and psychosocial pain researchers, as well as from recognized experts in sexual differentiation and reproductive endocrinology. We intend this document to serve as a utilitarian and thought-provoking guide for future research on sex and gender differences in pain and analgesia, both for those currently working in this field as well as those still wondering, "Do I really need to study females?"
Collapse
Affiliation(s)
- Joel D Greenspan
- Department of Biomedical Sciences, University of Maryland Dental School, University of Maryland, Baltimore, MD 21201-1510, USA Research Center for Neuroendocrine Influences on Pain, Baltimore, MD 21201-1510, USA Department of Psychology, Washington State University, Pullman, WA 99164-4820, USA Department of Oral Medicine, University of Washington, Seattle, WA 98195-6370, USA Laboratory for Experimental Pain Research, Department of Health Science and Technology, Center for Sensory-Motor Interaction, Aalborg University, Fredrik Bajers Vej 7, DK-9220 Aalborg, Denmark Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, FL 32306, USA Department of Community Dentistry and Behavioral Science, University of Florida College of Dentistry, Gainesville, FL 32610-3628, USA Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15260, USA Division of Surgery, Oncology, Reproductive Biology and Anaesthetics, Chelsea and Westminster Hospital, Imperial College, London SW10 9NH, UK Department of Physiological Psychology, University of Bamberg, Bamberg 96045, Germany Center for Neurovisceral Sciences and Women's Health, and Departments of Medicine, Psychiatry and Biobehavioral Sciences, and Physiology, UCLA School of Medicine, Los Angeles, CA 900095-1792, USA Department of Psychology, McGill University, Montreal, Canada PQ H3A 1B1 Department of Biology, Georgia State University, Atlanta, GA 30303-0389, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Dowers TS, Qin ZH, Thatcher GRJ, Bolton JL. Bioactivation of Selective Estrogen Receptor Modulators (SERMs). Chem Res Toxicol 2006; 19:1125-37. [PMID: 16978016 PMCID: PMC2517576 DOI: 10.1021/tx060126v] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tamara S Dowers
- Department of Medicinal Chemistry and Pharmacognosy (M/C 781), College of Pharmacy, University of Illinois at Chicago, 833 South Wood Street, Chicago, Illinois 60612-7231, USA
| | | | | | | |
Collapse
|
23
|
Zeisig R, Teppke AD, Behrens D, Fichtner I. Liposomal 4-hydroxy-tamoxifen: effect on cellular uptake and resulting cytotoxicity in drug resistant breast cancer cells in vitro. Breast Cancer Res Treat 2004; 87:245-54. [PMID: 15528967 DOI: 10.1007/s10549-004-8699-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The study was performed to investigate the potency of liposomal formulations to reduce or to overcome tamoxifen resistance. Therefore, estrogen receptor (ER) positive MCF-7 and ER deficient NCI/ADR cells with different sensitivity to tamoxifen were used. Instead of the parent compound, 4-hydroxytamoxifen (HT) was used as drug, because this metabolite is the most cytotoxic derivative in vitro. Liposomes further contained the membrane-active alkylphospholipid octadecyl-(1,1-dimethyl-piperidino-4-yl)-phosphate (OPP). Cellular uptake of HT during 3-24 h was determined by high performance thin layer chromatography technique (HPTLC). Free HT was taken up time independently by the two cell lines at 1.5-2.1 g HT/g cellular phosphate. Liposomal HT was taken up at a significantly higher degree than free HT in both cell lines, but the uptake was delayed in the sensitive MCF-7 cell line with the highest concentration detected after 24 h (3.5 g/g). Oppositely, the highest amount in the 'resistant' line (2.3 g/g) was already measured after 3 h in NCI/ADR cells. It successively decreased with incubation time. The faster uptake of liposomal HT by the NCI/ADR cells correlated with a stronger and earlier destruction of resistant NCI/ADR cells whereas the sensitive MCF-7 cells were mainly inhibited in their proliferation. Cytolytic effects were observed in both cell lines after extended incubation periods. The combination of HT with an alkylphospholipid further enhanced the cytotoxicity of the formulation. The IC50 in the NCI/ADR cells could be significantly reduced by liposomes combining both drugs to 15.1 microM compared with the IC50 of the free drugs (HT:28.9 microM; OPP: 36.8 microM). It is assumed that the enhanced and accelerated uptake of liposomal HT in the cell line with relative drug resistance can increase the intracellular bioavailability of HT. The results of this study demonstrated that liposomes with encapsulated antiestrogen have a superior cytotoxic effect in resistant breast cancer cells. That coincided with the enhanced therapeutic effect of these vesicles observed in vivo.
Collapse
Affiliation(s)
- Reinhard Zeisig
- Experimental Pharmacology Group, Max-Delbrück-Center for Molecular Medicine, Germany.
| | | | | | | |
Collapse
|
24
|
Greene GL, Shiau AK, Nettles KW. A structural explanation for ERalpha/ERbeta SERM discrimination. ERNST SCHERING RESEARCH FOUNDATION WORKSHOP 2004:33-45. [PMID: 15248503 DOI: 10.1007/978-3-662-05386-7_3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
Abstract
Many NRs have multiple subtypes that possess distinct expression patterns and that regulate distinct target genes. Antagonists generated through the addition of bulky side chains to agonist scaffolds are limited to being antagonistic on one or more subtypes of a particular NR. The passive antagonism mechanism, as revealed in our studies through direct comparison of the two THC-ER LBD complexes, suggests a new approach to achieving NR antagonism. Compounds could be designed to selectively stabilize the inactive conformations of certain NR subtypes and the active conformations of others. Such ligands are likely to exert novel biological and therapeutic effects.
Collapse
Affiliation(s)
- G L Greene
- Ben May Institute for Cancer Research, Department of Biochemistry and Molecular Biology, The University of Chicago, IL 60637, USA.
| | | | | |
Collapse
|
25
|
Zeisig R, Rückerl D, Fichtner I. Reduction of tamoxifen resistance in human breast carcinomas by tamoxifen-containing liposomes in vivo. Anticancer Drugs 2004; 15:707-14. [PMID: 15269602 DOI: 10.1097/01.cad.0000136885.65293.e9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We investigated whether it is possible to reduce anti-estrogen resistance using liposomally encapsulated tamoxifen in vivo. Small liposomal vesicles containing up to 5.1 mg tamoxifen/ml liposomal suspension, together with an alkylphospholipid to enhance the cellular uptake, were prepared and characterized. Mice transplanted with different tumor models were treated with tamoxifen liposomes administered i.p. or orally as a bolus dose of 50 mg/kg once a week or as a daily dose of 10 mg/kg/day, both during a 4-week period. After orally administered tamoxifen liposomes, tumor growth was significantly reduced for the 3366/tamoxifen (acquired resistance) and for the MCF-7 (inherent resistance) models to 47 and 16%, respectively (treated to control value of relative tumor volume). Intraperitoneal treatment with tamoxifen liposomes revealed similar results. Investigation of biodistribution revealed especially an accumulation of liposomal tamoxifen in MCF-7 tumors and livers of the treated mice. These liposomes had uterotrophic properties comparable to the dissolved compound. This study demonstrates for the first time that a liposomal formulation of tamoxifen was able to induce pharmacological effects and to improve the therapeutic efficacy in several anti-estrogen-resistant xenografts.
Collapse
Affiliation(s)
- Reiner Zeisig
- Max-Delbrück-Center for Molecular Medicine, Department of Experimental Pharmacology, Berlin, Germany.
| | | | | |
Collapse
|
26
|
Wang LH, Yang XY, Zhang X, Mihalic K, Fan YX, Xiao W, Howard OMZ, Appella E, Maynard AT, Farrar WL. Suppression of breast cancer by chemical modulation of vulnerable zinc fingers in estrogen receptor. Nat Med 2003; 10:40-7. [PMID: 14702633 DOI: 10.1038/nm969] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2003] [Accepted: 11/21/2003] [Indexed: 11/09/2022]
Abstract
Current antiestrogen therapy for breast cancer is limited by the mixed estrogenic and antiestrogenic activity of selective estrogen receptor modulators. Here we show that the function of zinc fingers in the estrogen receptor DNA-binding domain (DBD) is susceptible to chemical inhibition by electrophilic disulfide benzamide and benzisothiazolone derivatives, which selectively block binding of the estrogen receptor to its responsive element and subsequent transcription. These compounds also significantly inhibit estrogen-stimulated cell proliferation, markedly reduce tumor mass in nude mice bearing human MCF-7 breast cancer xenografts, and interfere with cell-cycle and apoptosis regulatory gene expression. Functional assays and computational analysis support a molecular mechanism whereby electrophilic agents preferentially disrupt the vulnerable C-terminal zinc finger, thus suppressing estrogen receptor-mediated breast carcinoma progression. Our results provide the proof of principle for a new strategy to inhibit breast cancer at the level of DNA binding, rather than the classical antagonism of estrogen binding.
Collapse
Affiliation(s)
- Li Hua Wang
- Basic Research Program, SAIC-Frederick, National Cancer Institute-Frederick, National Institutes of Health, PO Box B, Frederick, Maryland 21702, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Audesirk T, Cabell L, Kern M, Audesirk G. β-estradiol influences differentiation of hippocampal neurons in vitro through an estrogen receptor-mediated process. Neuroscience 2003; 121:927-34. [PMID: 14580943 DOI: 10.1016/s0306-4522(03)00294-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We utilized morphometric analysis of 3 day cultures of hippocampal neurons to determine the effects of both estradiol and the synthetic estrogen receptor modulator raloxifene on several parameters of neuronal growth and differentiation. These measurements included survival, neurite production, dendrite number, and axon and dendrite length and branching. 17 beta-Estradiol (10 nM) selectively stimulated dendrite branching; this effect was neither mimicked by alpha-estradiol, nor blocked by the estrogen receptor antagonist ICI 182780. The selective estrogen receptor modulator raloxifene (100 nM) neither mimicked nor reversed the effects of estradiol on dendritic branching. Western immunoblotting for the alpha and beta subtypes of estrogen receptor revealed the presence of alpha, but not beta, estrogen receptors in our hippocampal cultures. There is growing recognition of the effects of 17 beta-estradiol on neuronal development and physiology, with implications for brain sexual dimorphism, plasticity, cognition, and the maintenance of cognitive function during aging. The role of estradiol in hippocampal neuronal differentiation and function has particular implications for learning and memory. These data support the hypothesis that 17 beta-estradiol is acting via alpha estrogen receptors in influencing hippocampal development in vitro. Raloxifene, prescribed to combat osteoporosis in post-menopausal women, is a selective estrogen receptor modulator with tissue-specific agonist/antagonist properties. Because raloxifene had no effect on dendritic branching, we hypothesize that it does not interact with the alpha estrogen receptor in this experimental paradigm.
Collapse
Affiliation(s)
- T Audesirk
- Biology Department, University of Colorado at Denver, PO Box 173364, Denver, CO 80217-3364, USA.
| | | | | | | |
Collapse
|
28
|
Ray S, Rastogi R, Kumar A. Current status of estrogen receptors. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 2003; 59:201-32. [PMID: 12458968 DOI: 10.1007/978-3-0348-8171-5_7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Increasing knowledge on structure and function of estrogen receptors is providing information on the mechanism of action of estrogen agonists, as well as antagonists, and in understanding their tissue-selective action. However, there are still many factors associated with estrogen response which are poorly understood. Therefore, the task of designing a tissue-selective estrogen for use as a pharmaceutical in estrogen-dependent disorders remains an uncertain game. This review provides information on the current status of estrogen receptors for a better understanding.
Collapse
Affiliation(s)
- Suprabhat Ray
- Medicinal Chemistry Division, Central Drug Research Institute, Lucknow 226001, India.
| | | | | |
Collapse
|
29
|
Fichtner I, Reszka R, Arndt D, Zeisig R. Animal experiments-an essential component for the development of liposomal anticancer agents. J Liposome Res 2003; 13:9-15. [PMID: 12725721 DOI: 10.1081/lpr-120017483] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Iduna Fichtner
- Max-Delbrück-Center for Molecular Medicine, Berlin-Buch, Germany
| | | | | | | |
Collapse
|
30
|
Schreurs RHMM, Quaedackers ME, Seinen W, van der Burg B. Transcriptional activation of estrogen receptor ERalpha and ERbeta by polycyclic musks is cell type dependent. Toxicol Appl Pharmacol 2002; 183:1-9. [PMID: 12217637 DOI: 10.1006/taap.2002.9458] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the past decade the list of chemicals in the environment that are able to mimic the natural hormone estrogen, thereby disrupting endocrine function, has grown rapidly. These chemicals are able to bind to estrogen receptors (ERs) and influence estrogen signaling pathways, although several of them have structures that differ substantially from the endogenous hormone 17beta-estradiol. Because of their polycyclic nature, the polycyclic musks AHTN (6-acetyl-1,1,2,4,4,7-hexamethyltetraline) and HHCB (1,2,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-gamma-2-benzopyran) were assessed for interaction with estrogen receptors. These compounds are ubiquitously present in surface waters and have been identified in human milk fat and blood. Using sensitive in vitro reporter gene assays, we found that AHTN and HHCB act as selective estrogen receptor modulators (SERMs), inducing both estrogenic and antiestrogenic activity dependent on the cell line and the ER subtype targeted. Weak estrogenic effects were observed only at relatively high concentrations (10 microM). Antiestrogenic effects were observed in various cell lines starting at concentrations of 0.1 microM. In comparison with the well-known SERM, 4-hydroxytamoxifen, AHTN and HHCB have a much lower potency in suppressing estradiol-induced transactivation. Results with various mutant ER receptor types suggest that binding sites of the musk compounds differ from 17beta-estradiol and 4-hydroxytamoxifen. The cell type dependency of ER transactivation shows that caution should be exerted when interpreting effects of estrogenic compounds using in vitro systems.
Collapse
|
31
|
Koide A, Abbatiello S, Rothgery L, Koide S. Probing protein conformational changes in living cells by using designer binding proteins: application to the estrogen receptor. Proc Natl Acad Sci U S A 2002; 99:1253-8. [PMID: 11818562 PMCID: PMC122176 DOI: 10.1073/pnas.032665299] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A challenge in understanding the mechanism of protein function in biology is to establish the correlation between functional form in the intracellular environment and high-resolution structures obtained with in vitro techniques. Here we present a strategy to probe conformational changes of proteins inside cells. Our method involves: (i) engineering binding proteins to different conformations of a target protein, and (ii) using them to sense changes in the surface property of the target in cells. We probed ligand-induced conformational changes of the estrogen receptor alpha (ER alpha) ligand-binding domain (LBD). By using yeast two-hybrid techniques, we first performed combinatorial library screening of "monobodies" (small antibody mimics using the scaffold of a fibronectin type III domain) for clones that bind to ER alpha and then characterized their interactions with ER alpha in the nucleus, the native environment of ER alpha, in the presence of various ligands. A library using a highly flexible loop yielded monobodies that specifically recognize a particular ligand complex of ER alpha, and the pattern of monobody specificity was consistent with the structural differences found in known crystal structures of ER alpha-LBD. A more restrained loop library yielded clones that bind both agonist- and antagonist-bound ER alpha. Furthermore, we found that a deletion of the ER alpha F domain that is C-terminally adjacent to the LBD increased the crossreactivity of monobodies to the apo-ER alpha-LBD, suggesting a dynamic nature of the ER alpha-LBD conformation and a role of the F domain in restraining the LBD in an inactive conformation.
Collapse
Affiliation(s)
- Akiko Koide
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | | | | | | |
Collapse
|
32
|
Valliant JF, Schaffer P, Stephenson KA, Britten JF. Synthesis of boroxifen, a nido-carborane analogue of tamoxifen. J Org Chem 2002; 67:383-7. [PMID: 11798307 DOI: 10.1021/jo0158229] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A nido-carborane analogue of tamoxifen, the widely employed breast cancer therapy agent, was prepared as an archetype of a potential new class of antiestrogen and boron neutron capture therapy agent in which the carborane is incorporated within the framework of the parent compound. The carborane was introduced through the reaction of 6,9-bis(acetonitrile)decaborane with a unique and highly conjugated ene-yne, which was prepared stereoselectively. NMR spectroscopy and a crystal structure of a key intermediate, the carborane analogue of chloro-tamoxifen, demonstrated the structural similarities between the tamoxifen carboranes and their corresponding phenyl analogues.
Collapse
Affiliation(s)
- John F Valliant
- Department of Chemistry and The Medical Physics Unit, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada, L8S 4M1.
| | | | | | | |
Collapse
|
33
|
Abstract
The human estrogen receptor-alpha (hER) is a ligand-activated transcription factor that functions as a homodimer. We sought to further understand the molecular processes involved in dimerization, and to develop a reagent that may function as an antiestrogen independent of the ligand binding site. To this end, we designed a 16-residue 'dimer-interface' oligopeptide derived from the helical region of the hER which is directly involved in dimerization. This peptide, termed the I-box peptide, has a high helical propensity in aqueous solution. The I-box peptide blocks hER action by causing aggregation and precipitation of both the ligand-bound and apo-hER. This effect is dependent on the helical nature of the peptide. A single Ile to Pro mutation in the helical region of the I-box peptide significantly reduces the helical content and abolishes the precipitation activity. Furthermore, the peptide activity appears to be specific for the hER. The I-box peptide does not significantly affect other proteins or steroid receptors tested. A homologous peptide derived from the nuclear receptor RXRalpha dimer interface, and a LXXLL-containing peptide from the coactivator TIF2 have no detectable in vitro effect on hER function or solubility. Our data suggest that rationally designed molecules capable of affecting steroid receptor quaternary structures may be potential avenues for the development of specific inhibitors of this class of proteins.
Collapse
Affiliation(s)
- M R Yudt
- Department of Biochemistry and Biophysics, Box 712, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | | |
Collapse
|
34
|
Abstract
The continued widespread prevalence of breast cancer supports placing a high priority on research aimed at its primary prevention, particularly among women who are at increased risk for developing this disease. The suggestion of potential agents for the primary chemoprevention of breast cancer evolved out of the treatment setting. Extensive experience with tamoxifen, a first-generation selective estrogen receptor modulator (SERM) showing efficacy, first, in the treatment of advanced breast cancer and, subsequently, as adjuvant therapy for early stage disease established the safety of this agent. Cumulative data from multiple adjuvant studies documented the efficacy of tamoxifen in reducing second primary breast cancers in the contralateral breast, supporting its potential as a chemopreventive agent for breast cancer. The safety and second primary data on tamoxifen, together with extensive information on its pharmacokinetics, metabolism, and antitumor effects, as well as its potentially beneficial effects on lipid metabolism and osteoporosis, led the National Surgical Adjuvant Breast and Bowel Project (NSABP) to select tamoxifen for testing in the first prospective randomized phase III trial of the efficacy of a chemopreventive agent for preventing breast cancer in women at increased risk of the disease. Accordingly, in 1992 the NSABP started the Breast Cancer Prevention Trial (P-1) in which 13,388 women > or = 35 years of age who were at increased risk of breast cancer according to Gail model risk factors [family history, age, and personal history (i.e., age at first birth, age at menarche, previous breast biopsies)] were randomized to tamoxifen 20 mg/day or placebo for 5 years. Through 69 months of follow-up tamoxifen reduced the risk of invasive breast cancer, primarily estrogen receptor-positive tumors, by 49% (two-sided p < 0.00001). Tamoxifen reduced the risk of noninvasive breast cancer by 50% (two-sided p < 0.002). In addition, tamoxifen reduced fractures of the hip, radius, and spine, but it had no effect on the rate of ischemic heart disease. As previously shown, the rates of endometrial cancer and vascular events increased with tamoxifen. With the P-1 results establishing tamoxifen as the standard of care for the primary chemoprevention of breast cancer in high-risk women, concern over the side effects of tamoxifen has prompted a continuing search for an agent that displays a more desirable efficacy/toxicity profile. Raloxifene, a second-generation SERM approved for the prevention of osteoporosis in postmenopausal women, displays antiestrogenic properties in the breast and possibly the endometrium, and estrogenic effects in the bone and on the lipid profile, suggesting it as a candidate for comparison with the chemopreventive standard, tamoxifen. Raloxifene will be compared to tamoxifen in an equivalency trial, the Study of Tamoxifen and Raloxifene (STAR) NSABP P-2, which began in July 1999 at almost 500 centers in North America. The plan is to randomize 22,000 postmenopausal women > or = 35 years of age at increased risk of breast cancer by Gail criteria to tamoxifen 20 mg/day or raloxifene 60 mg/day for 5 years. Study endpoints include invasive and noninvasive breast cancer, cardiovascular disease, endometrial cancer, bone fractures, and vascular events.
Collapse
Affiliation(s)
- B K Dunn
- Division of Cancer Prevention, National Cancer Institute, Bethesda, Maryland, USA
| | | |
Collapse
|
35
|
Abstract
Tamoxifen is one of the most effective drugs to be used in the treatment of women with breast cancer and as a chemopreventive agent in women 'at risk' from this disease. Tamoxifen can be regarded as a paradigm for a new range of selective oestrogen receptor modulators that include toremifene, used in the treatment of metastatic breast cancer and raloxifene, presently approved for use in postmenopausal women for the treatment of osteoporosis. Tamoxifen treatment of women leads to a small increase in the incidence of endometrial cancers. It is important to understand the mechanism for this side effect in order to predict the likely human risk for other drugs of this class. Two such mechanisms have been proposed: (1) conversion of the drug to electrophilic metabolites that damage cellular DNA; and (2) an oestrogen agonist action on the uterus, promoting endogenous lesions. In rats, long-term tamoxifen treatment results in liver cancer via a genotoxic mechanism. However, it seems most likely that, in women treated with tamoxifen, endometrial cancer is related to an oestrogen agonist effect of this drug, promoting uterine cell proliferation.
Collapse
Affiliation(s)
- I N White
- MRC Toxicology Unit, Hodgkin Building, University of Leicester, Lancaster Road, LE1 9HN, Leicester, UK.
| |
Collapse
|
36
|
Li XF, Carter SJ, Dovichi NJ. Non-aqueous capillary electrophoresis of tamoxifen and its acid hydrolysis products. J Chromatogr A 2000; 895:81-5. [PMID: 11105850 DOI: 10.1016/s0021-9673(00)00661-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Tamoxifen and its acid hydrolysis products were separated and tentatively identified by non-aqueous capillary electrophoresis with thermooptical absorbance and electrospray ionization mass spectrometry. Acid hydrolysis is a convenient method of generating tamoxifen degradation products. The parent compound and seven hydrolysis products were separated in 9 min.
Collapse
Affiliation(s)
- X F Li
- Department of Chemistry, University of Alberta, Edmonton, Canada
| | | | | |
Collapse
|
37
|
Abstract
Despite a recent trend toward improvement in the U.S. breast cancer mortality rate, breast cancer incidence (182,800 new cases anticipated in 2000) and mortality figures (over 40,800 anticipated deaths) remain the highest and second highest, respectively, of all cancers in U.S. women. In 1998, the selective-estrogen-receptor-modulator (SERM) tamoxifen achieved positive results in the Breast Cancer Prevention Trial (BCPT), leading to the Food and Drug Administration (FDA) approval of tamoxifen for risk reduction in women at high risk of breast cancer (the historic first FDA approval of a cancer preventive agent). This brought about a paradigm shift in new approaches for controlling breast cancer toward pharmacologic preventive regimens, called chemoprevention. This paper presents a comprehensive clinical review of breast cancer prevention study, highlighting issues of the extensive study of tamoxifen. These issues include the record of primary tamoxifen results in several breast-cancer risk-reduction settings (primary, adjuvant, and ductal carcinoma in situ [DCIS]); critical secondary BCPT risk-benefit findings (including quality of life issues) and their effects on counseling patients on use of tamoxifen for prevention; ethic minorities; optimal tamoxifen dose/duration; and potential impact on mortality and other issues involved with potential net benefit to society. Other breast-cancer chemoprevention issues reviewed here include women at high genetic risk (especially BRCA1 mutation carriers); raloxifene in breast cancer prevention; other SERMs; SERM resistance; and new agents and combinations currently in development. Very recent developments involving PPAR-gamma ligands, COX-2 inhibitors, and RXR-ligands are discussed in the section on new drug development.
Collapse
Affiliation(s)
- P H Brown
- Breast Center, Department of Medicine, Baylor College of Medicine, Houston, Texas, USA
| | | |
Collapse
|
38
|
Block K, Kardana A, Igarashi P, Taylor HS. In utero diethylstilbestrol (DES) exposure alters Hox gene expression in the developing müllerian system. FASEB J 2000; 14:1101-8. [PMID: 10834931 DOI: 10.1096/fasebj.14.9.1101] [Citation(s) in RCA: 202] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Diethylstilbestrol (DES) was widely used to treat pregnant women through 1971. The reproductive tracts of their female offspring exposed to DES in utero are characterized by anatomic abnormalities. Here we show that DES administered to mice in utero produces changes in the expression pattern of several Hox genes that are involved in patterning of the reproductive tract. DES produces posterior shifts in Hox gene expression and homeotic anterior transformations of the reproductive tract. In human uterine or cervical cell cultures, DES induces HOXA9 or HOXA10 gene expression, respectively, to levels approximately twofold that induced by estradiol. The DES-induced expression is not inhibited by cyclohexamide. Estrogens are novel morphogens that directly regulate the expression pattern of posterior Hox genes in a manner analogous to retinoic acid regulation of anterior Hox genes. Alterations in HOX gene expression are a molecular mechanism by which DES affects reproductive tract development. Changes in Hox gene expression are a potential marker for the effects of in utero drug use that may become apparent only at late stages of development.
Collapse
Affiliation(s)
- K Block
- Department of Obstetrics and Gynecology, Yale University School of Medicine, New Haven, Connecticut 06520, USA
| | | | | | | |
Collapse
|
39
|
Kim SH, Katzenellenbogen JA. Triarylethylene bisphenols with a novel cycle are ligands for the estrogen receptor. Bioorg Med Chem 2000; 8:785-93. [PMID: 10819167 DOI: 10.1016/s0968-0896(00)00016-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We have prepared a series of triarylethylene and triarylethane systems, analogues of the selective antiestrogen tamoxifen, in which the alkyl substituent is tethered to the distal, rather than the proximal aryl ring by a 5-, 6-, or 7-membered carbocycle. This unusual cyclic structure rigidifies the ligand and adds bulk in a manner that is different from the more typical cyclization to the proximal aryl ring, as in the antiestrogen nafoxidine. These new systems were prepared efficiently by the addition of a benzylic sodium reagent, generated from the corresponding chloride by treatment with sodium naphthalenide, to a doubly protected 4,4'-dihydroxybenzophenone, followed by dehydration and deprotection. In all cases, formation of the exocyclic alkene was preferred. Two of the corresponding alkanes could be obtained by catalytic hydrogenation. All of these compounds have relatively high binding affinity for the estrogen receptor, and some of them demonstrate a significant level of affinity selectivity for the estrogen receptor alpha subtype. Accommodation of these newly rigidified cyclic triarylethylene systems into the ligand-binding pocket of the estrogen receptor can be visualized by molecular modeling.
Collapse
Affiliation(s)
- S H Kim
- Department of Chemistry, University of Illinois, Urbana 61801, USA
| | | |
Collapse
|
40
|
Ferrucci L, Benvenuti E, Bartali B, Bandinelli S, Di Iorio A, Russo CR, Lauretani F. Preventive health care for older women: life-style recommendations and new directions. AGING (MILAN, ITALY) 2000; 12:113-31. [PMID: 10902053 DOI: 10.1007/bf03339898] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
One of the key paradoxes in gerontology is that, despite a higher longevity, aging women experience worse health and longer disability than men. However, there is growing evidence that changes in life-style, medical interventions and systematic screening for certain diseases may substantially reduce the excess risk of major chronic conditions and disability in aging women, and therefore improve the quality of their late life. The potentials and public health implications of prevention in older women have been recently emphasized, not only by the scientific literature, but also by the media. More and more women are turning to their primary care physicians or other health professionals to seek counselling and help on how to reduce the burden of chronic disease and disability in old age by quitting smoking, eating a healthy diet, increasing physical activity, and coping with stress. Hormone replacement therapy also has a central role in this action of prevention. To maximize compliance, women should be provided a few guidelines that are easy to understand, and can be followed without interfering too much with their daily life activities. This article reviews the current literature on prevention in older women to select preventive strategies that are based on robust scientific evidence. This list of guidelines should be considered as a starting point for all those who are in charge of caring for middle-aged and older women.
Collapse
|
41
|
Abstract
Estrogen-induced hamster kidney tumor model serves as a useful model to study the biochemical and molecular mechanisms of hormonal carcinogenesis. In this model, we have demonstrated an increased expression of estrogen receptor mRNA and protein in estrogen-treated kidneys and in estrogen-induced tumors. The sequence information for hamster estrogen receptor gene is not known and has been investigated in this study. A hamster uterus cDNA library was constructed and the 5'-region of the hamster estrogen receptor cDNA cloned from this library using polymerase chain reaction (PCR) methodology. Additionally, hamster kidney polyadenylated RNA was reverse transcribed and PCR amplified using primers that were designed based on maximum homology between mouse, rat and human estrogen receptor cDNAs. These PCR amplified fragments were cloned into plasmid vectors and clones with the expected size of the insert subjected to Southern blot analysis using human estrogen receptor cDNA as a probe. The positive clones on Southern blot analysis and the PCR amplified products from these clones were subjected to DNA sequence analysis. Using this strategy, a full length, 1978 bp hamster estrogen receptor cDNA has been cloned which shows 87% homology with human, 90% with rat and 91% with mouse estrogen receptor cDNA. The deduced amino acid shares 88% homology with human, and 93% with rat and mouse estrogen receptors. Hamster estrogen receptor domain C (DNA binding domain) shows a 100% homology with a similar domain from mouse, rat, human, pig, sheep, horse and chicken estrogen receptor (Genebank reference ID: AF 181077).
Collapse
Affiliation(s)
- H K Bhat
- Division of Laboratory Research and Development, Department of Medicine, Charles R. Drew University of Medicine and Science, 1731 East 120th Street, Los Angeles, CA 90059, USA
| | | |
Collapse
|
42
|
Webb P, Nguyen P, Valentine C, Lopez GN, Kwok GR, McInerney E, Katzenellenbogen BS, Enmark E, Gustafsson JA, Nilsson S, Kushner PJ. The estrogen receptor enhances AP-1 activity by two distinct mechanisms with different requirements for receptor transactivation functions. Mol Endocrinol 1999; 13:1672-85. [PMID: 10517669 DOI: 10.1210/mend.13.10.0357] [Citation(s) in RCA: 228] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Estrogen receptors (ERs alpha and beta) enhance transcription in response to estrogens by binding to estrogen response elements (EREs) within target genes and utilizing transactivation functions (AF-1 and AF-2) to recruit p160 coactivator proteins. The ERs also enhance transcription in response to estrogens and antiestrogens by modulating the activity of the AP-1 protein complex. Here, we examine the role of AF-1 and AF-2 in ER action at AP-1 sites. Estrogen responses at AP-1 sites require the integrity of the ERalpha AF-1 and AF-2 activation surfaces and the complementary surfaces on the p160 coactivator GRIP1 (glucocorticoid receptor interacting protein 1), the NID/AF-1 region, and NR boxes. Thus, estrogen-liganded ERalpha utilizes the same protein-protein contacts to transactivate at EREs and AP-1 sites. In contrast, antiestrogen responses are strongly inhibited by ERalpha AF-1 and weakly inhibited by AF-2. Indeed, ERalpha truncations that lack AF-1 enhance AP-1 activity in the presence of antiestrogens, but not estrogens. This phenotype resembles ERbeta, which naturally lacks constitutive AF-1 activity. We conclude that the ERs enhance AP-1 responsive transcription by distinct mechanisms with different requirements for ER transactivation functions. We suggest that estrogen-liganded ER enhances AP-1 activity via interactions with p160s and speculate that antiestrogen-liganded ER enhances AP-1 activity via interactions with corepressors.
Collapse
Affiliation(s)
- P Webb
- Metabolic Research Unit, University of California School of Medicine, San Francisco 94143, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
43
|
Leung LK, Wang TT. Paradoxical regulation of Bcl-2 family proteins by 17beta-oestradiol in human breast cancer cells MCF-7. Br J Cancer 1999; 81:387-92. [PMID: 10507761 PMCID: PMC2362930 DOI: 10.1038/sj.bjc.6690706] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Tumorigenesis is related to the dysregulation of cell growth or cell death pathways. Hence, elucidation of the mechanisms involved in the modulation of pro- or anti-apoptotic proteins is important in furthering understanding of breast cancer aetiology and may aid in designing prevention and treatment strategies. In the present study, we examined the role of 17beta-oestradiol on the regulation of apoptosis in the breast cancer cell line MCF-7. Using multi-probe RNAase protection assays, we found changes in the mRNA levels of several Bcl-2 family proteins upon treatment of MCF-7 cells with 17beta-oestradiol. Unexpectedly, we found a paradoxical effects of 17beta-oestradiol on two anti-apoptotic proteins Bcl-2 and Bcl-x. Treatment with 17beta-oestradiol resulted in up-regulation of Bcl-2 mRNA and protein, but down-regulated Bcl-x(L) mRNA and protein. The effect of 17beta-oestradiol on Bcl-x(L) occurred at concentration-dependent fashion. The effect was specific to 17beta-oestradiol since other steroid hormones exert no effect on Bcl-x(L). Tamoxifen, an anti-oestrogen, blocked the down-regulation of Bcl-x(L) by 17beta-oestradiol demonstrating this effect is oestrogen receptor-dependent. We speculate that different members of the Bcl-2 family proteins may be regulated through different pathway and these pathways may be modulated by 17beta-oestradiol.
Collapse
Affiliation(s)
- L K Leung
- Basic Research Laboratory, Division of Basic Sciences, National Cancer Institute, Frederick, MD 21702-1201, USA
| | | |
Collapse
|
44
|
Chlebowski RT, Collyar DE, Somerfield MR, Pfister DG. American Society of Clinical Oncology technology assessment on breast cancer risk reduction strategies: tamoxifen and raloxifene. J Clin Oncol 1999; 17:1939-55. [PMID: 10561236 DOI: 10.1200/jco.1999.17.6.1939] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
OBJECTIVE To conduct an evidence-based technology assessment to determine whether tamoxifen and raloxifene as breast cancer risk-reduction strategies are appropriate for broad-based conventional use in clinical practice. POTENTIAL INTERVENTION Tamoxifen and raloxifene. OUTCOME Outcomes of interest include breast cancer incidence, breast cancer-specific survival, overall survival, and net health benefits. EVIDENCE A comprehensive, formal literature review was conducted for tamoxifen and raloxifene on the following topics: breast cancer risk reduction; tamoxifen side effects and toxicity, including endometrial cancer risk; tamoxifen influences on nonmalignant diseases, including coronary heart disease and osteoporosis; and decision making by women at risk for breast cancer. Testimony was collected from invited experts and interested parties. VALUES More weight was given to publications that described randomized trials. BENEFITS/HARMS/COSTS: The American Society of Clinical Oncology (ASCO) Working Group acknowledges that a woman's decision regarding breast cancer risk-reduction strategies will depend on the importance and weight attributed to the information provided regarding both cancer and non-cancer-related risks. CONCLUSIONS For women with a defined 5-year projected risk of breast cancer of >/= 1.66%, tamoxifen (at 20 mg/d for up to 5 years) may be offered to reduce their risk. It is premature to recommend raloxifene use to lower the risk of developing breast cancer outside of a clinical trial setting. On the basis of available information, use of raloxifene should currently be reserved for its approved indication to prevent bone loss in postmenopausal women. Conclusions are based on single-agent use of the drugs. At the present time, the effect of using tamoxifen or raloxifene with other medications (such as hormone replacement therapy), or using tamoxifen and raloxifene in combination or sequentially, has not been studied adequately. The continuing use of placebo-controlled trials in other risk-reduction trials highlights the current unanswered issues concerning the use of such interventions, especially when the influence on net health benefit remains to be determined. Breast cancer risk reduction is a rapidly evolving area. This technology assessment represents an ongoing process with existing plans to monitor and review data and to update recommendations in a timely matter. (See VALIDATION The conclusions of the Working Group were evaluated by the ASCO Health Services Research Committee and by the ASCO Board of Directors. SPONSOR American Society of Clinical Oncology.
Collapse
Affiliation(s)
- R T Chlebowski
- American Society of Clinical Oncology, Alexandria, VA 22314, USA
| | | | | | | |
Collapse
|
45
|
Affiliation(s)
- F Liebermann
- Department of Neurology, Mt. Sinai School of Medicine, New York, NY, USA
| | | |
Collapse
|
46
|
Moreno A, Clemente J, Crespo C, Martínez A, Navarro M, Fernández L, Minguell J, Vázquez G, Andreu FJ. Pelvic insufficiency fractures in patients with pelvic irradiation. Int J Radiat Oncol Biol Phys 1999; 44:61-6. [PMID: 10219795 DOI: 10.1016/s0360-3016(98)00534-3] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Insufficiency fractures (IF) occur as a result of normal physiological stress on bones with deficient elastic resistance. Pelvic insufficiency fractures are a complication of osteoporosis due to postmenopausal status, high dose of corticosteroids, or local irradiation. They are important because differential diagnosis includes pelvic bone metastases. Diagnosis is based on both clinical manifestations and radiographic and scintigraphic findings. METHODS AND MATERIALS We examined eight patients with pelvic cancer who had previously undergone external beam radiation therapy as part of their treatment. In the follow-up, they developed insufficiency fractures, and no factor other than pelvic irradiation was present. Diagnosis was confirmed by radionuclide bone scan followed by conventional radiography and computed tomography (CT) scan. RESULTS The average onset of symptoms was 13.7 months after radiation therapy was completed. The initial symptom in all cases was pain. In all of the patients, the bone scan showed abnormalities. One to four increased uptake foci were observed, in the sacroiliac joint in all cases, and in the pubis in three cases. The initial diagnosis was bone metastases in five patients. CT scan showed fractures in all of the patients, in sacrum and pubis, both endostic and cortical. Treatment, consisting of nonsteroidal anti-inflammatory drugs and rest, led to symptomatic relief in all cases. CONCLUSION Knowledge of pelvic insufficiency fractures is essential in order to rule out metastasic disease, and thus avoid inaccurate treatment. Although radionuclide bone scan is useful in early detection of pelvic IF, definitive diagnosis is provided by CT scan.
Collapse
Affiliation(s)
- A Moreno
- Department of Radiation Oncology, University Hospital of San Juan, Alicante, Spain.
| | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Shiau AK, Barstad D, Loria PM, Cheng L, Kushner PJ, Agard DA, Greene GL. The structural basis of estrogen receptor/coactivator recognition and the antagonism of this interaction by tamoxifen. Cell 1998; 95:927-37. [PMID: 9875847 DOI: 10.1016/s0092-8674(00)81717-1] [Citation(s) in RCA: 1865] [Impact Index Per Article: 71.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Ligand-dependent activation of transcription by nuclear receptors (NRs) is mediated by interactions with coactivators. Receptor agonists promote coactivator binding, and antagonists block coactivator binding. Here we report the crystal structure of the human estrogen receptor alpha (hER alpha) ligand-binding domain (LBD) bound to both the agonist diethylstilbestrol (DES) and a peptide derived from the NR box II region of the coactivator GRIP1 and the crystal structure of the hER alpha LBD bound to the selective antagonist 4-hydroxytamoxifen (OHT). In the DES-LBD-peptide complex, the peptide binds as a short alpha helix to a hydrophobic groove on the surface of the LBD. In the OHT-LBD complex, helix 12 occludes the coactivator recognition groove by mimicking the interactions of the NR box peptide with the LBD. These structures reveal the two distinct mechanisms by which structural features of OHT promote this "autoinhibitory" helix 12 conformation.
Collapse
Affiliation(s)
- A K Shiau
- Howard Hughes Medical Institute and the Department of Biochemistry and Biophysics, University of California at San Francisco, 94143-0448, USA
| | | | | | | | | | | | | |
Collapse
|
48
|
Women's health literatureWatch. J Womens Health (Larchmt) 1998; 7:1175-84. [PMID: 9861595 DOI: 10.1089/jwh.1998.7.1175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
49
|
Affiliation(s)
- S M Lippman
- Department of Clinical Cancer Prevention, The University of Texas M. D. Anderson Cancer Center, Houston 77030, USA
| | | | | |
Collapse
|
50
|
Komm BS, Bodine PV. The ongoing saga of osteoporosis treatment. J Cell Biochem 1998; 72 Suppl 30-31:277-283. [DOI: 10.1002/(sici)1097-4644(1998)72:30/31+<277::aid-jcb33>3.0.co;2-l] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/1998] [Accepted: 09/23/1998] [Indexed: 11/08/2022]
|