1
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Sun X, Tang F, Guo Q, Liu Y, He Y, Du Y, Gao F, Zhang G, Yang C. HAS2-Ezrin-ER axis plays a role in acquired antiestrogen resistance of ER-positive breast cancer. Front Pharmacol 2022; 13:1031487. [PMID: 36386154 PMCID: PMC9659586 DOI: 10.3389/fphar.2022.1031487] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 10/20/2022] [Indexed: 08/13/2023] Open
Abstract
The development of endocrine resistance is a major clinical problem in estrogen receptor-positive (ER+) breast cancer (BrCa) treatment, in which how cancer cells acquire resistance remains obscure. Hyaluronan synthase 2 (HAS2) is the most critical synthase in producing hyaluronan and is well known for its involvement in cancer growth, metabolism and metastasis. Recent evidence has proved that HAS2 is involved in cellular acquired resistance to drug therapy in BrCa. In this work, we first observed that HAS2 expression was decreased in the endocrine-resistant ER+ BrCa cells. Further knocking-out experiments confirmed that the loss of HAS2 in parental ER+ BrCa cells resulted in a following antiestrogen resistance. Next, we found that the HAS2-loss could induce an upregulation of Ezrin, a member of the membrane cytoskeletal protein family who plays key roles in cellular signal transduction. Notably, we identified that the increase of Ezrin induced by HAS2-loss could inhibit the ERα expression and augment antiestrogen resistance, suggesting that a HAS2-Ezrin-ER axis may be associated with the acquirement of endocrine resistance in ER+ BrCa cells. Finally, knockdown or inhibition of Ezrin could restore the sensitivity of endocrine-resistant cells to antiestrogens treatment by activating ERα signaling. Taken together, our findings unraveled a novel HAS2-Ezrin-ER route in regulating the sensitivity of ER+ BrCa cells to antiestrogens, in which Ezrin may be a potential target in endocrine therapy.
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Affiliation(s)
- Xiaodan Sun
- Department of Clinical Laboratory, Shanghai Sixth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Department of Molecular Biology, Shanghai Sixth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Fen Tang
- Department of Breast Surgery, Shanghai Sixth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qian Guo
- Department of Molecular Biology, Shanghai Sixth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yiwen Liu
- Department of Molecular Biology, Shanghai Sixth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yiqing He
- Department of Molecular Biology, Shanghai Sixth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yan Du
- Department of Molecular Biology, Shanghai Sixth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Feng Gao
- Department of Clinical Laboratory, Shanghai Sixth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Department of Molecular Biology, Shanghai Sixth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Guoliang Zhang
- Department of Clinical Laboratory, Shanghai Sixth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Department of Molecular Biology, Shanghai Sixth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Cuixia Yang
- Department of Clinical Laboratory, Shanghai Sixth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Department of Molecular Biology, Shanghai Sixth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
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2
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Scheidemann ER, Shajahan-Haq AN. Resistance to CDK4/6 Inhibitors in Estrogen Receptor-Positive Breast Cancer. Int J Mol Sci 2021; 22:12292. [PMID: 34830174 PMCID: PMC8625090 DOI: 10.3390/ijms222212292] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/09/2021] [Accepted: 11/10/2021] [Indexed: 12/12/2022] Open
Abstract
Estrogen receptor-positive (ER+) breast cancer is the most common form of breast cancer. Antiestrogens were the first therapy aimed at treating this subtype, but resistance to these warranted the development of a new treatment option. CDK4/6 inhibitors address this problem by halting cell cycle progression in ER+ cells, and have proven to be successful in the clinic. Unfortunately, both intrinsic and acquired resistance to CDK4/6 inhibitors are common. Numerous mechanisms of how resistance occurs have been identified to date, including the activation of prominent growth signaling pathways, the loss of tumor-suppressive genes, and noncanonical cell cycle function. Many of these have been successfully targeted and demonstrate the ability to overcome resistance to CDK4/6 inhibitors in preclinical and clinical trials. Future studies should focus on the development of biomarkers so that patients likely to be resistant to CDK4/6 inhibition can initially be given alternative methods of treatment.
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Affiliation(s)
| | - Ayesha N. Shajahan-Haq
- Lombardi Comprehensive Cancer Center, Department of Oncology, Georgetown University Medical Center, Washington, DC 20057, USA;
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3
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Lloyd V, Morse M, Purakal B, Parker J, Benard P, Crone M, Pfiffner S, Szmyd M, Dinda S. Hormone-Like Effects of Bisphenol A on p53 and Estrogen Receptor Alpha in Breast Cancer Cells. Biores Open Access 2019; 8:169-184. [PMID: 31681507 PMCID: PMC6823605 DOI: 10.1089/biores.2018.0048] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Bisphenol A (BPA) is a polymerizing agent commonly found in plastics that has been linked to xenoestrogenic activity. In this study, we analyzed the estrogen-like effects of BPA on the expression of estrogen receptor (ER)α and p53 with hormonal and antihormonal treatments in T-47D and MCF-7 cells. Cells were cultured in medium containing 5% charcoal-stripped fetal bovine serum for 6 days to deplete any endogenous steroids or effectors. The cells were then treated for 24 h with 600 nM BPA, which was determined to be the optimal value by a concentration study of BPA from 1 nM to 2 μM. Extracted cellular proteins were quantified and subjected to sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE)/Western blot analysis. The cell proliferation assays were quantified upon exposure to BPA. Laser confocal microscopy was performed to determine the cytolocalization of p53 and ERα upon treatment with BPA. Western blot analysis revealed that BPA caused an increase in the cellular protein p53 in a concentration-dependent manner. While treatment with BPA did not affect the cytolocalization of p53, an increase in cell proliferation was observed. Our studies provide interesting leads to delineate the possible mechanistic relationship among BPA, ER, and tumor suppressor proteins in breast cancer cells.
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Affiliation(s)
- Victoria Lloyd
- Department of Biomedical Diagnostic and Therapeutic Sciences, School of Health Sciences, Center of Biomedical Research, Oakland University, Rochester, Michigan
| | - Mia Morse
- Department of Biomedical Diagnostic and Therapeutic Sciences, School of Health Sciences, Center of Biomedical Research, Oakland University, Rochester, Michigan
| | - Betsy Purakal
- Department of Biomedical Diagnostic and Therapeutic Sciences, School of Health Sciences, Center of Biomedical Research, Oakland University, Rochester, Michigan
| | - Jordan Parker
- Department of Biomedical Diagnostic and Therapeutic Sciences, School of Health Sciences, Center of Biomedical Research, Oakland University, Rochester, Michigan
| | - Paige Benard
- Department of Biomedical Diagnostic and Therapeutic Sciences, School of Health Sciences, Center of Biomedical Research, Oakland University, Rochester, Michigan
| | - Michael Crone
- Department of Biomedical Diagnostic and Therapeutic Sciences, School of Health Sciences, Center of Biomedical Research, Oakland University, Rochester, Michigan
| | - Samantha Pfiffner
- Department of Biomedical Diagnostic and Therapeutic Sciences, School of Health Sciences, Center of Biomedical Research, Oakland University, Rochester, Michigan
| | - Monica Szmyd
- Department of Biomedical Diagnostic and Therapeutic Sciences, School of Health Sciences, Center of Biomedical Research, Oakland University, Rochester, Michigan
| | - Sumi Dinda
- Department of Biomedical Diagnostic and Therapeutic Sciences, School of Health Sciences, Center of Biomedical Research, Oakland University, Rochester, Michigan
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4
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Abstract
Uterine fibroids are the most common gynecological disorder, classically requiring surgery when symptomatic. Although attempts at finding a nonsurgical cure date back to centuries, it is only around the middle of the last century that serious attempts at a medical treatment were carried out. Initially, both progestins and estrogen–progestin combinations have been utilized, although proof of their usefulness is lacking. A major step forward was achieved when peptide analogs of the GnRH were introduced, first those with superagonist properties and subsequently those acting as antagonists. Initially, the latter produced side effects preventing their routine utilization; eventually, this problem was overcome following the synthesis of cetrorelix. Because both types of analogs produce hypoestrogenism, their use is limited to a maximum of 6 months and, for this reason, today they are utilized as an adjuvant treatment before surgery with overall good results. Over the last decade, new, nonpeptidic, orally active GnRH-receptor blockers have also been synthesized. One of them, Elagolix, is in the early stages of testing in women with fibroids. Another fundamental development has been the utilization of the so-called selective progesterone receptor modulators, sometimes referred to as “antiprogestins”. The first such compound to be applied to the long-term treatment of fibroids was Mifepristone; today, this compound is mostly used outside of Western Countries, where the substance of choice is Ulipristal acetate. Large clinical trials have proven the effectiveness of Ulipristal in the long-term medical therapy of fibroids, although some caution must be exercised because of the rare occurrence of liver complications. All selective progesterone receptor modulators produce unique endometrial changes that are today considered benign, reversible, and without negative consequences. In conclusion, long-term medical treatment of fibroids seems possible today, especially in premenopausal women.
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Affiliation(s)
- Manuela Farris
- Department of Gynecology, Obstetrics and Urology, Sapienza, University of Rome, Rome, Italy, .,The Italian Association for Demographic Education, Rome, Italy,
| | - Carlo Bastianelli
- Department of Gynecology, Obstetrics and Urology, Sapienza, University of Rome, Rome, Italy,
| | - Elena Rosato
- Department of Gynecology, Obstetrics and Urology, Sapienza, University of Rome, Rome, Italy,
| | - Ivo Brosens
- Faculty of Medicine, KU Leuven, Leuven, Belgium
| | - Giuseppe Benagiano
- Department of Gynecology, Obstetrics and Urology, Sapienza, University of Rome, Rome, Italy,
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5
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González-González A, Mediavilla MD, Sánchez-Barceló EJ. Melatonin: A Molecule for Reducing Breast Cancer Risk. Molecules 2018; 23:E336. [PMID: 29415446 PMCID: PMC6017232 DOI: 10.3390/molecules23020336] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 01/31/2018] [Accepted: 01/31/2018] [Indexed: 01/10/2023] Open
Abstract
The objective of this article is to review the basis supporting the usefulness of melatonin as an adjuvant therapy for breast cancer (BC) prevention in several groups of individuals at high risk for this disease. Melatonin, as a result of its antiestrogenic and antioxidant properties, as well as its ability to improve the efficacy and reduce the side effects of conventional antiestrogens, could safely be associated with the antiestrogenic drugs presently in use. In individuals at risk of BC due to night shift work, the light-induced inhibition of melatonin secretion, with the consequent loss of its antiestrogenic effects, would be countered by administering this neurohormone. BC risk from exposure to metalloestrogens, such as cadmium, could be treated with melatonin supplements to individuals at risk of BC due to exposure to this xenoestrogen. The BC risk related to obesity may be reduced by melatonin which decrease body fat mass, inhibits the enhanced aromatase expression in obese women, increases adiponectin secretion, counteracts the oncogenic effects of elevated concentrations of leptin; and decreases blood glucose levels and insulin resistance. Despite compelling experimental evidence of melatonin's oncostatic actions being susceptible to lowering BC risk, there is still a paucity of clinical trials focused on this subject.
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Affiliation(s)
- Alicia González-González
- Department of Physiology and Pharmacology, School of Medicina, University of Cantabria, 39011 Santander, Spain.
| | - María Dolores Mediavilla
- Department of Physiology and Pharmacology, School of Medicina, University of Cantabria, 39011 Santander, Spain.
| | - Emilio J Sánchez-Barceló
- Department of Physiology and Pharmacology, School of Medicina, University of Cantabria, 39011 Santander, Spain.
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6
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Aleck K, Hallman K, Quigley M, Lloyd V, Szmyd M, Ruskin D, Bedgood T, Dinda S. Effects of Atrial Natriuretic Peptide on p53 and Estrogen Receptor in Breast Cancer Cells. Biores Open Access 2017; 6:141-150. [PMID: 29098120 PMCID: PMC5665415 DOI: 10.1089/biores.2017.0009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The atrial natriuretic peptide (ANP) hormone is secreted by cardiac atrial myocytes and acts to regulate blood pressure homeostasis in humans. Previous research indicates ANP treatment significantly decreases the proliferation of human prostate cancer cells, pancreatic adenocarcinoma, and breast cancer cells. Minimal studies have been conducted with regard to ANP regulating tumor suppressor genes and steroid hormone receptors in breast cancer cells. Our study analyzed the effects of ANP in combination with 17β-estradiol (E2) and antiestrogen treatments on p53 and ERα levels in T-47D breast cancer cells. Preliminary studies through Western blot analysis showed that ANP treatment decreases p53 and ERα expression levels in a concentration-dependent (10-100 nM) manner. Treatment with ANP alone, at a 100 nM concentration, causes a decrease of p53 and ERα expression compared with Cs (control stripped), but with E2 and antiestrogen combinations, expression of both protein levels decreased compared with treatments without ANP. Combined treatment with E2, an estrogen antagonist, and ANP decreased cellular proliferation compared with treatments without ANP, except in the case of raloxifene (RAL). Our studies indicate that ANP has potential as a therapeutic breast cancer treatment and should inspire further studies on the molecular mechanism of ANP in T-47D breast cancer cells.
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Affiliation(s)
- Katie Aleck
- Department of Biomedical Diagnostic Therapeutic Sciences, School of Health Sciences, Institute for Stem Cell Research and Center for Biomedical Research, Oakland University, Rochester, Michigan
| | - Kelly Hallman
- Department of Biomedical Diagnostic Therapeutic Sciences, School of Health Sciences, Institute for Stem Cell Research and Center for Biomedical Research, Oakland University, Rochester, Michigan
| | - Meghan Quigley
- Department of Biomedical Diagnostic Therapeutic Sciences, School of Health Sciences, Institute for Stem Cell Research and Center for Biomedical Research, Oakland University, Rochester, Michigan
| | - Victoria Lloyd
- Department of Biomedical Diagnostic Therapeutic Sciences, School of Health Sciences, Institute for Stem Cell Research and Center for Biomedical Research, Oakland University, Rochester, Michigan
| | - Monica Szmyd
- Department of Biomedical Diagnostic Therapeutic Sciences, School of Health Sciences, Institute for Stem Cell Research and Center for Biomedical Research, Oakland University, Rochester, Michigan
| | - Dana Ruskin
- Department of Biomedical Diagnostic Therapeutic Sciences, School of Health Sciences, Institute for Stem Cell Research and Center for Biomedical Research, Oakland University, Rochester, Michigan
| | - Tyler Bedgood
- Department of Biomedical Diagnostic Therapeutic Sciences, School of Health Sciences, Institute for Stem Cell Research and Center for Biomedical Research, Oakland University, Rochester, Michigan
| | - Sumi Dinda
- Department of Biomedical Diagnostic Therapeutic Sciences, School of Health Sciences, Institute for Stem Cell Research and Center for Biomedical Research, Oakland University, Rochester, Michigan
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7
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Hallman K, Aleck K, Quigley M, Dwyer B, Lloyd V, Szmyd M, Dinda S. The regulation of steroid receptors by epigallocatechin-3-gallate in breast cancer cells. Breast Cancer (Dove Med Press) 2017; 9:365-373. [PMID: 28579831 PMCID: PMC5447698 DOI: 10.2147/bctt.s131334] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
It has been reported that phytoestrogen epigallocatechin gallate (EGCG) suppresses cancer cell proliferation and may have antitumor properties. In this study, we analyzed the effects of EGCG on estrogen receptor α (ERα) and progesterone receptor in hormone-dependent T-47D breast cancer cells. Western blot analysis revealed EGCG induced a concentration-dependent decrease in ERα protein levels, with a 56% reduction occurring with 60 µM EGCG when compared to controls. Downregulation of ERα protein levels was observed after 24-hour co-treatment of T-47D cells with 60 µM EGCG and 10 nM 17β-estradiol (E2). The proliferative effect of E2 on cell viability was reversed when treated in combination with EGCG. In contrast, the combination of EGCG with the pure ER antagonist, ICI 182, 780, showed no further reduction in cell number as only 5% of the cells were viable after 6 days of treatment. These studies may provide further understanding of the interactions among flavonoids and steroid receptors in breast cancer cells.
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Affiliation(s)
- Kelly Hallman
- Biomedical Diagnostic and Therapeutic Sciences, School of Health Sciences, Center for Biomedical Research, Oakland University, Rochester, MI, USA
| | - Katie Aleck
- Biomedical Diagnostic and Therapeutic Sciences, School of Health Sciences, Center for Biomedical Research, Oakland University, Rochester, MI, USA
| | - Meghan Quigley
- Biomedical Diagnostic and Therapeutic Sciences, School of Health Sciences, Center for Biomedical Research, Oakland University, Rochester, MI, USA
| | - Brigitte Dwyer
- Biomedical Diagnostic and Therapeutic Sciences, School of Health Sciences, Center for Biomedical Research, Oakland University, Rochester, MI, USA
| | - Victoria Lloyd
- Biomedical Diagnostic and Therapeutic Sciences, School of Health Sciences, Center for Biomedical Research, Oakland University, Rochester, MI, USA
| | - Monica Szmyd
- Biomedical Diagnostic and Therapeutic Sciences, School of Health Sciences, Center for Biomedical Research, Oakland University, Rochester, MI, USA
| | - Sumi Dinda
- Biomedical Diagnostic and Therapeutic Sciences, School of Health Sciences, Center for Biomedical Research, Oakland University, Rochester, MI, USA
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8
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Saluzzo J, Hallman KM, Aleck K, Dwyer B, Quigley M, Mladenovik V, Siebert AE, Dinda S. The regulation of tumor suppressor protein, p53, and estrogen receptor (ERα) by resveratrol in breast cancer cells. Genes Cancer 2016; 7:414-25. [PMID: 28191286 DOI: 10.18632/genesandcancer.125] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Resveratrol (RES) is a natural antioxidant found abundantly in grapes, peanuts, and berries, and is known to possess anti-tumorigenic properties. However, there is a noticeable lack of studies on the mechanistic effects of Resveratrol on tumor suppressors. Previous studies from our laboratory have shown the tumor suppressor protein p53 and estrogen receptor-alpha (ERα) to be possible molecular targets for RES. In this study, the anti-estrogenic effects of RES were analyzed on the expression of ERα and p53. The breast cancer cells grown in stripped serum were treated with 60 μM RES, as the optimum concentration based on data obtained from a concentration study using 1-100 μM RES. Our studies indicate that RES caused a decrease in the levels of protein expression of p53 and ERα as compared to the control. Increasing concentrations of RES caused a four-fold decrease in cell number in comparison to estradiol. RES, in conjunction with ICI 182,780 (ICI), caused a down-regulation of both p53 and ERα as compared to the control. These observed effects on cell proliferation and regulation of both p53 and ERα by RES may lead to further understanding of the relationship between tumor suppressor proteins and steroid receptors in breast cancer cells.
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9
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Abstract
About 70% of breast tumors express estrogen receptor alpha (ERα), which mediates the proliferative effects of estrogens on breast epithelial cells, and are candidates for treatment with antiestrogens, steroidal or non-steroidal molecules designed to compete with estrogens and antagonize ERs. The variable patterns of activity of antiestrogens (AEs) in estrogen target tissues and the lack of systematic cross-resistance between different types of molecules have provided evidence for different mechanisms of action. AEs are typically classified as selective estrogen receptor modulators (SERMs), which display tissue-specific partial agonist activity (e.g. tamoxifen and raloxifene), or as pure AEs (e.g. fulvestrant), which enhance ERα post-translational modification by ubiquitin-like molecules and accelerate its proteasomal degradation. Characterization of second- and third-generation AEs, however, suggests the induction of diverse ERα structural conformations, resulting in variable degrees of receptor downregulation and different patterns of systemic properties in animal models and in the clinic.
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MESH Headings
- Animals
- Antineoplastic Agents, Hormonal/chemistry
- Antineoplastic Agents, Hormonal/pharmacology
- Antineoplastic Agents, Hormonal/therapeutic use
- Breast Neoplasms/drug therapy
- Breast Neoplasms/genetics
- Breast Neoplasms/mortality
- Breast Neoplasms/pathology
- Clinical Trials as Topic
- Drug Evaluation, Preclinical
- Drug Resistance, Neoplasm
- Estrogen Antagonists/chemistry
- Estrogen Antagonists/pharmacology
- Estrogen Antagonists/therapeutic use
- Estrogen Receptor alpha/antagonists & inhibitors
- Estrogen Receptor alpha/chemistry
- Estrogen Receptor alpha/metabolism
- Female
- Gene Expression Profiling
- Gene Expression Regulation, Neoplastic/drug effects
- Humans
- Models, Molecular
- Molecular Conformation
- Molecular Structure
- Mutation
- Protein Binding
- Protein Processing, Post-Translational
- Receptors, Estrogen/antagonists & inhibitors
- Receptors, Estrogen/chemistry
- Receptors, Estrogen/genetics
- Receptors, Estrogen/metabolism
- Selective Estrogen Receptor Modulators/chemistry
- Selective Estrogen Receptor Modulators/pharmacology
- Selective Estrogen Receptor Modulators/therapeutic use
- Structure-Activity Relationship
- Treatment Outcome
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Affiliation(s)
- T Traboulsi
- Institute for Research in Immunology and CancerUniversité de Montréal, Montréal, Québec, Canada
- Department of Biochemistry and Molecular MedicineUniversité de Montréal, Montréal, Québec, Canada
| | - M El Ezzy
- Institute for Research in Immunology and CancerUniversité de Montréal, Montréal, Québec, Canada
| | - J L Gleason
- Department of ChemistryMcGill University, Montréal, Québec, Canada
| | - S Mader
- Institute for Research in Immunology and CancerUniversité de Montréal, Montréal, Québec, Canada
- Department of Biochemistry and Molecular MedicineUniversité de Montréal, Montréal, Québec, Canada
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10
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Lau KM, To KF. Importance of Estrogenic Signaling and Its Mediated Receptors in Prostate Cancer. Int J Mol Sci 2016; 17:ijms17091434. [PMID: 27589731 PMCID: PMC5037713 DOI: 10.3390/ijms17091434] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 08/16/2016] [Accepted: 08/23/2016] [Indexed: 12/12/2022] Open
Abstract
Prostate cancer (PCa) treatment was first established by Huggins and Hodges in 1941, primarily described as androgen deprivation via interference of testicular androgen production. The disease remains incurable with relapse of hormone-refractory cancer after treatments. Epidemiological and clinical studies disclosed the importance of estrogens in PCa. Discovery of estrogen receptor ERβ prompted direct estrogenic actions, in conjunction with ERα, on PCa cells. Mechanistically, ERs upon ligand binding transactivate target genes at consensus genomic sites via interactions with various transcriptional co-regulators to mold estrogenic signaling. With animal models, Noble revealed estrogen dependencies of PCa, providing insight into potential uses of antiestrogens in the treatment. Subsequently, various clinical trials were conducted and molecular and functional consequences of antiestrogen treatment in PCa were delineated. Besides, estrogens can also trigger rapid non-genomic signaling responses initiated at the plasma membrane, at least partially via an orphan G-protein-coupled receptor GPR30. Activation of GPR30 significantly inhibited in vitro and in vivo PCa cell growth and the underlying mechanism was elucidated. Currently, molecular networks of estrogenic and antiestrogenic signaling via ERα, ERβ and GPR30 in PCa have not been fully deciphered. This crucial information could be beneficial to further developments of effective estrogen- and antiestrogen-based therapy for PCa patients.
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Affiliation(s)
- Kin-Mang Lau
- Department of Anatomical and Cellular Pathology, State Key Laboratory of Oncology in Southern China, and Sir YK Pao Centre for Cancer, The Chinese University of Hong Kong, Hong Kong, China.
| | - Ka-Fai To
- Department of Anatomical and Cellular Pathology, State Key Laboratory of Oncology in Southern China, and Sir YK Pao Centre for Cancer, The Chinese University of Hong Kong, Hong Kong, China.
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11
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Abstract
Cancer chemoprevention refers to the use of agents for the inhibition, delay, or reversal of carcinogenesis before invasion. In the present review, agents examined in the context of cancer chemoprevention are classified in four major categories—hormonal, medications, diet-related agents, and vaccines—and the main representatives of each category are presented. Although there are serious constraints in the documentation of effectiveness of chemopreventive agents, mainly stemming from the long latency of the condition they are addressing and the frequent lack of intermediate biomarkers, there is little disagreement about the role of aspirin, whereas a diet rich in vegetables and fruits appears to convey more protection than individual micronutrients. Among categories of cancer chemopreventive agents, hormonal ones and vaccines might hold more promise for the future. Also, the identification of individuals who would benefit most from chemopreventive interventions on the basis of their genetic profiles could open new prospects for cancer chemoprevention.
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Affiliation(s)
- Vassiliki Benetou
- Department of Hygiene, Epidemiology and Medical Statistics, University of Athens Medical School, Athens, GR-115 27, Greece
| | - Areti Lagiou
- Department of Public Health and Community Health, Faculty of Health Professions, Athens Technological Educational Institute (TEI Athens), Athens, Greece
| | - Pagona Lagiou
- Department of Hygiene, Epidemiology and Medical Statistics, University of Athens Medical School, Athens, GR-115 27, Greece; Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA
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12
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Abstract
Understanding the molecular changes that drive an acquired antiestrogen resistance phenotype is of major clinical relevance. Previous methodologies for addressing this question have taken a single gene/pathway approach and the resulting gains have been limited in terms of their clinical impact. Recent systems biology approaches allow for the integration of data from high throughput "-omics" technologies. We highlight recent advances in the field of antiestrogen resistance with a focus on transcriptomics, proteomics and methylomics.
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Affiliation(s)
- Kerrie B Bouker
- Department of Oncology and Lombardi Comprehensive Cancer Center, Georgetown University School of Medicine, Washington, DC 20057, U.S.A
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13
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Collins-Burow BM, Antoon JW, Frigo DE, Elliott S, Weldon CB, Boue SM, Beckman BS, Curiel TJ, Alam J, McLachlan JA, Burow ME. Antiestrogenic activity of flavonoid phytochemicals mediated via the c-Jun N-terminal protein kinase pathway. Cell-type specific regulation of estrogen receptor alpha. J Steroid Biochem Mol Biol 2012; 132:186-93. [PMID: 22634477 PMCID: PMC4083692 DOI: 10.1016/j.jsbmb.2012.05.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 05/12/2012] [Accepted: 05/14/2012] [Indexed: 12/14/2022]
Abstract
Flavonoid phytochemicals act as both agonists and antagonists of the human estrogen receptors (ERs). While a number of these compounds act by directly binding to the ER, certain phytochemicals, such as the flavonoid compounds chalcone and flavone, elicit antagonistic effects on estrogen signaling independent of direct receptor binding. Here we demonstrate both chalcone and flavone function as cell type-specific selective ER modulators. In MCF-7 breast carcinoma cells chalcone and flavone suppress ERα activity through stimulation of the stress-activated members of the mitogen-activated protein kinase (MAPK) family: c-Jun N-terminal kinase (JNK)1 and JNK2. The use of dominant-negative mutants of JNK1 or JNK2 in stable transfected cells established that the antiestrogenic effects of chalcone and flavone required intact JNK signaling. We further show that constitutive activation of the JNK pathway partially suppresses estrogen (E2)-mediated gene expression in breast, but not endometrial carcinoma cells. Our results demonstrate a role for stress-activated MAPKs in the cell type-specific regulation of ERα function.
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Affiliation(s)
- Bridgette M. Collins-Burow
- Tulane University Medical Center, New Orleans, Louisiana 70112
- Center for Bioenvironmental Research at Tulane and Xavier Universities, New Orleans, Louisiana 70112
- Department of Medicine, Section of Hematology & Medical Oncology, New Orleans, Louisiana 70112
| | - James W. Antoon
- Tulane University Medical Center, New Orleans, Louisiana 70112
- Department of Medicine, Section of Hematology & Medical Oncology, New Orleans, Louisiana 70112
- Department of Pharmacology, New Orleans, Louisiana 70112
| | - Daniel E. Frigo
- Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, TX
| | - Steven Elliott
- Tulane University Medical Center, New Orleans, Louisiana 70112
- Department of Medicine, Section of Hematology & Medical Oncology, New Orleans, Louisiana 70112
| | - Christopher B. Weldon
- Tulane University Medical Center, New Orleans, Louisiana 70112
- Department of Medicine, Section of Hematology & Medical Oncology, New Orleans, Louisiana 70112
| | - Stephen M. Boue
- U. S. Department of Agriculture, Agricultural Research Service, Southern Regional Research Center, New Orleans, LA 70179
| | - Barbara S. Beckman
- Center for Bioenvironmental Research at Tulane and Xavier Universities, New Orleans, Louisiana 70112
- Department of Medicine, Section of Hematology & Medical Oncology, New Orleans, Louisiana 70112
| | - Tyler J. Curiel
- Cancer Therapy & Research Center, University of Texas Health Science Center, San Antonio
| | - Jawed Alam
- Alton Ochsner Medical Foundation, Department of Molecular Genetics, New Orleans, Louisiana 70121
| | - John A. McLachlan
- Tulane University Medical Center, New Orleans, Louisiana 70112
- Center for Bioenvironmental Research at Tulane and Xavier Universities, New Orleans, Louisiana 70112
| | - Matthew E. Burow
- Tulane University Medical Center, New Orleans, Louisiana 70112
- Center for Bioenvironmental Research at Tulane and Xavier Universities, New Orleans, Louisiana 70112
- Department of Medicine, Section of Hematology & Medical Oncology, New Orleans, Louisiana 70112
- To whom correspondence and requests for reprints should be addressed: Matthew E. Burow, Tulane University Health Sciences Center, Department of Medicine, Section of Hematology & Medical Oncology, 1430 Tulane Ave. SL-78, New Orleans, LA 70112, Phone: 504-988-6688, Fax: 504-988-5483,
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14
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Abstract
The mainstay targets for hormonal prostate cancer (PCa) therapies are based on negating androgen action. Recent epidemiologic and experimental data have pinpointed the key roles of estrogens in PCa development and progression. Racial and geographic differences, as well as age-associated changes, in estrogen synthesis and metabolism contribute significantly to the etiology. This article summarizes how different estrogens/antiestrogens/estrogen mimics contribute to prostate carcinogenesis, the roles of the different mediators of estrogen in the process, and the potentials of new estrogenic/antiestrogenic compounds for prevention and treatment of PCa.
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Affiliation(s)
- Shuk-Mei Ho
- Department of Environmental Health, Center for Environmental Genetics, and the Cancer Institute, College of Medicine, University of Cincinnati, Cincinnati, Ohio
| | - Ming-tsung Lee
- Department of Environmental Health, College of Medicine, University of Cincinnati, Cincinnati, Ohio. Telephone 513-558-0595, Fax 513-558-0071,
| | - Hung-Ming Lam
- Department of Environmental Health, College of Medicine, University of Cincinnati, Cincinnati, Ohio. Telephone 513-558-0595, Fax 513-558-0071,
| | - Yuet-Kin Leung
- Department of Environmental Health, Center for Environmental Genetics, and The Cancer Institute, College of Medicine, University of Cincinnati, Cincinnati, Ohio. Telephone 513-558-5181, Fax 513-558-0071,
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15
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Wu F, Khan S, Wu Q, Barhoumi R, Burghardt R, Safe S. Ligand structure-dependent activation of estrogen receptor alpha/Sp by estrogens and xenoestrogens. J Steroid Biochem Mol Biol 2008; 110:104-15. [PMID: 18400491 PMCID: PMC2519242 DOI: 10.1016/j.jsbmb.2008.02.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2007] [Revised: 02/12/2008] [Accepted: 02/12/2008] [Indexed: 12/15/2022]
Abstract
This study investigated the effects of E2, diethylstilbestrol (DES), antiestrogens, the phytoestrogen resveratrol, and the xenoestrogens octylphenol (OP), nonylphenol (NP), endosulfan, kepone, 2,3,4,5-tetrachlorobiphenyl-4-ol (HO-PCB-Cl(4)), bisphenol-A (BPA), and 2,2-bis-(p-hydroxyphenyl)-1,1,1-trichloroethane (HPTE) on induction of luciferase activity in breast cancer cells transfected with a construct (pSp1(3)) containing three tandem GC-rich Sp binding sites linked to luciferase and wild-type or variant ERalpha. The results showed that induction of luciferase activity was highly structure-dependent in both MCF-7 and MDA-MB-231 cells. Moreover, RNA interference assays using small inhibitory RNAs for Sp1, Sp3 and Sp4 also demonstrated structure-dependent differences in activation of ERalpha/Sp1, ERalpha/Sp3 and ERalpha/Sp4. These results demonstrate for the first time that various structural classes of ER ligands differentially activate wild-type and variant ERalpha/Sp-dependent transactivation, selectively use different Sp proteins, and exhibit selective ER modulator (SERM)-like activity.
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Affiliation(s)
- Fei Wu
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843
| | - Shaheen Khan
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX 77843
| | - Qian Wu
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843
| | - Rola Barhoumi
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843
| | - Robert Burghardt
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843
| | - Stephen Safe
- Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station, TX 77843
- Institute of Biosciences and Technology, Texas A&M University, Health Science Center, Houston, TX 77030
- Correspondence should be sent to: Stephen Safe, Department of Veterinary Physiology and Pharmacology, Texas A&M University, 4466 TAMU, Vet. Res. Bldg. 410, College Station, TX 77843-4466, Tel: 979-845-5988 / Fax: 979-862-4929,
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16
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Sabnis GJ, Macedo L, Goloubeva O, Schayowitz A, Zhu Y, Brodie A. Toremifene-atamestane; alone or in combination: predictions from the preclinical intratumoral aromatase model. J Steroid Biochem Mol Biol 2008; 108:1-7. [PMID: 17942301 PMCID: PMC3081608 DOI: 10.1016/j.jsbmb.2007.04.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2006] [Accepted: 04/05/2007] [Indexed: 11/24/2022]
Abstract
Since most breast cancers occur in postmenopausal women and are hormone dependent, we developed a model system that mimics this situation. In this model, tumors of human estrogen receptor (ER) positive breast cancer cells stably transfected with aromatase (Ac-1) are grown in immune-compromised mice. Using this model we have explored a number of therapeutic strategies to maximize the antitumor efficacy of antiestrogens (AEs) and aromatase inhibitors (AIs). This intratumoral aromatase xenograft model has proved accurate in predicting the outcome of several clinical trials. In this current study we compared the effect of an AE toremifene and steroidal AI atamestane, alone or in combination, on growth of hormone-dependent human breast cancer. We have also compared toremifene plus atamestane combination with tamoxifen in this study. The growth of Ac-1 cells was inhibited by tamoxifen, toremifene and atamestane in vitro with IC(50) values of 1.8+/-1.3 microM, 1+/-0.3 microM and 60.4+/-17.2 microM, respectively. The combination of toremifene plus atamestane was found to be better than toremifene or atamestane alone in vitro. The effect of this combination was then studied in vivo using Ac-1 xenografts grown in ovariectomized female SCID mice. The mice were injected with toremifene (1000 microg/day), atamestane (1000 microg/day), tamoxifen (100 microg/day), or the combination of toremifene plus atamestane. In this study, our results indicate that the combination of toremifene plus atamestane was as effective as toremifene or tamoxifen alone but may not provide any additional benefit over toremifene alone or tamoxifen alone.
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Affiliation(s)
- Gauri J Sabnis
- Department of Pharmacology and Experimental Therapeutics, University of Maryland Baltimore, Baltimore, MD 21201
| | - Luciana Macedo
- Department of Pharmacology and Experimental Therapeutics, University of Maryland Baltimore, Baltimore, MD 21201
| | - Olga Goloubeva
- University of Maryland Greenebaum Cancer Center, Baltimore, MD 21201
| | - Adam Schayowitz
- Department of Pharmacology and Experimental Therapeutics, University of Maryland Baltimore, Baltimore, MD 21201
| | - Yue Zhu
- Department of Pharmacology and Experimental Therapeutics, University of Maryland Baltimore, Baltimore, MD 21201
| | - Angela Brodie
- Department of Pharmacology and Experimental Therapeutics, University of Maryland Baltimore, Baltimore, MD 21201
- University of Maryland Greenebaum Cancer Center, Baltimore, MD 21201
- To whom the correspondence should be addressed, at Department of Pharmacology and Experimental Therapeutics University of Maryland, Baltimore School of Medicine, Health Science Facility I, Room 580G 685 W. Baltimore St. Baltimore, MD 21201. Phone (410)706-3137, Fax (410)706-0032,
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17
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Chu I, Sun J, Arnaout A, Kahn H, Hanna W, Narod S, Sun P, Tan CK, Hengst L, Slingerland J. p27 phosphorylation by Src regulates inhibition of cyclin E-Cdk2. Cell 2007; 128:281-94. [PMID: 17254967 PMCID: PMC1961623 DOI: 10.1016/j.cell.2006.11.049] [Citation(s) in RCA: 284] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2006] [Revised: 10/03/2006] [Accepted: 11/20/2006] [Indexed: 01/02/2023]
Abstract
The kinase inhibitor p27Kip1 regulates the G1 cell cycle phase. Here, we present data indicating that the oncogenic kinase Src regulates p27 stability through phosphorylation of p27 at tyrosine 74 and tyrosine 88. Src inhibitors increase cellular p27 stability, and Src overexpression accelerates p27 proteolysis. Src-phosphorylated p27 is shown to inhibit cyclin E-Cdk2 poorly in vitro, and Src transfection reduces p27-cyclin E-Cdk2 complexes. Our data indicate that phosphorylation by Src impairs the Cdk2 inhibitory action of p27 and reduces its steady-state binding to cyclin E-Cdk2 to facilitate cyclin E-Cdk2-dependent p27 proteolysis. Furthermore, we find that Src-activated breast cancer lines show reduced p27 and observe a correlation between Src activation and reduced nuclear p27 in 482 primary human breast cancers. Importantly, we report that in tamoxifen-resistant breast cancer cell lines, Src inhibition can increase p27 levels and restore tamoxifen sensitivity. These data provide a new rationale for Src inhibitors in cancer therapy.
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Affiliation(s)
- Isabel Chu
- Braman Family Breast Cancer Institute, and Department of Biochemistry and Molecular Biology, U. of Miami Miller School of Medicine, Miami, Florida; U.S.A
- Departments of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Jun Sun
- Braman Family Breast Cancer Institute, and Department of Biochemistry and Molecular Biology, U. of Miami Miller School of Medicine, Miami, Florida; U.S.A
| | - Angel Arnaout
- Surgery, University of Toronto, Toronto, Ontario, Canada
| | - Harriette Kahn
- Pathobiology and Lab Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Wedad Hanna
- Pathobiology and Lab Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Steven Narod
- Pathobiology and Lab Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Ping Sun
- Pathobiology and Lab Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Cheng-Keat Tan
- Braman Family Breast Cancer Institute, and Department of Biochemistry and Molecular Biology, U. of Miami Miller School of Medicine, Miami, Florida; U.S.A
| | - Ludger Hengst
- Division of Medical Biochemistry, Biocenter - Innsbruck Medical University, Innsbruck, Austria
| | - Joyce Slingerland
- Braman Family Breast Cancer Institute, and Department of Biochemistry and Molecular Biology, U. of Miami Miller School of Medicine, Miami, Florida; U.S.A
- Departments of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
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18
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Zujewski J, Vaughn-Cooke A, Flanders KC, Eckhaus MA, Lubet RA, Wakefield LM. Transforming growth factors-beta are not good biomarkers of chemopreventive efficacy in a preclinical breast cancer model system. Breast Cancer Res 2001; 3:66-75. [PMID: 11250748 PMCID: PMC13902 DOI: 10.1186/bcr273] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2000] [Revised: 10/10/2000] [Accepted: 10/19/2000] [Indexed: 12/03/2022] Open
Abstract
Using a carcinogen-initiated rat model of mammary tumorigenesis, we tested the hypothesis that transforming growth factor (TGF)-betas are useful biomarkers of chemopreventive efficacy in the breast. The chemopreventive agents tested were tamoxifen and the retinoids 9-cis-retinoic acid (9cRA) and N-(4-hydroxyphenyl)retinamide (4-HPR), because both antiestrogens and retinoids have previously been shown to upregulate TGF-betas in vitro. Despite demonstrable chemopreventive efficacy in this model, none of these agents, alone or in combination, had any significant impact on the expression of TGF-betas in the mammary ductal epithelium or periductal stroma as determined by immunohistochemistry. These data suggest that TGF-betas are not likely to be useful biomarkers of chemopreventive efficacy in a clinical setting.
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Affiliation(s)
- JoAnne Zujewski
- Medicine Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Anika Vaughn-Cooke
- Medicine Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Kathleen C Flanders
- Laboratory of Cell Regulation and Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Michael A Eckhaus
- Veterinary Resources Program, Office of the Director, National Institutes of Health, Bethesda, Maryland, USA
| | - Ronald A Lubet
- Division of Cancer Prevention, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Lalage M Wakefield
- Laboratory of Cell Regulation and Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
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19
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Andersen HR, Andersson AM, Arnold SF, Autrup H, Barfoed M, Beresford NA, Bjerregaard P, Christiansen LB, Gissel B, Hummel R, Jørgensen EB, Korsgaard B, Le Guevel R, Leffers H, McLachlan J, Møller A, Nielsen JB, Olea N, Oles-Karasko A, Pakdel F, Pedersen KL, Perez P, Skakkeboek NE, Sonnenschein C, Soto AM. Comparison of short-term estrogenicity tests for identification of hormone-disrupting chemicals. Environ Health Perspect 1999; 107 Suppl 1:89-108. [PMID: 10229711 PMCID: PMC1566352 DOI: 10.1289/ehp.99107s189] [Citation(s) in RCA: 213] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The aim of this study was to compare results obtained by eight different short-term assays of estrogenlike actions of chemicals conducted in 10 different laboratories in five countries. Twenty chemicals were selected to represent direct-acting estrogens, compounds with estrogenic metabolites, estrogenic antagonists, and a known cytotoxic agent. Also included in the test panel were 17beta++-estradiol as a positive control and ethanol as solvent control. The test compounds were coded before distribution. Test methods included direct binding to the estrogen receptor (ER), proliferation of MCF-7 cells, transient reporter gene expression in MCF-7 cells, reporter gene expression in yeast strains stably transfected with the human ER and an estrogen-responsive reporter gene, and vitellogenin production in juvenile rainbow trout. 17beta-Estradiol, 17alpha-ethynyl estradiol, and diethylstilbestrol induced a strong estrogenic response in all test systems. Colchicine caused cytotoxicity only. Bisphenol A induced an estrogenic response in all assays. The results obtained for the remaining test compounds--tamoxifen, ICI 182.780, testosterone, bisphenol A dimethacrylate, 4-n-octylphenol, 4-n-nonylphenol, nonylphenol dodecylethoxylate, butylbenzylphthalate, dibutylphthalate, methoxychlor, o,p'-DDT, p,p'-DDE, endosulfan, chlomequat chloride, and ethanol--varied among the assays. The results demonstrate that careful standardization is necessary to obtain a reasonable degree of reproducibility. Also, similar methods vary in their sensitivity to estrogenic compounds. Thus, short-term tests are useful for screening purposes, but the methods must be further validated by additional interlaboratory and interassay comparisons to document the reliability of the methods.
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Affiliation(s)
- H R Andersen
- Department of Environmental Medicine, Odense University, Denmark.
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20
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Abstract
A number of metabolic changes within the liver occur concurrent with hepatic regeneration. These processes suggest that the administration of an antiestrogen might alter the rate of hepatic regeneration. To examine this question, male Wistar rats were treated with tamoxifen (0.1 mg/rat/day or 1.0 mg/rat/day) or vehicle for three days prior to and after partial hepatectomy, and the anatomic and biochemical process of hepatic regeneration was assessed. Tamoxifen administration caused a dose-dependent decrease in the hepatic cytosolic estrogen receptor activity and, conversely, a dose-dependent increase in cytosolic androgen receptor activity. Despite these changes in baseline hepatic sex steroid receptor status, all receptor activities were comparable between the three groups within 24 hr of partial hepatectomy. Moreover, no differences in any of the parameters assessing hepatic regeneration following partial hepatectomy were evident: liver-body ratio, ornithine decarboxylase activity, and thymidine kinase activity. This lack of effect of tamoxifen treatment on hepatic regeneration suggests either that estrogens do not play a role in the modulation of liver growth after partial hepatectomy or that, once initiated, the regenerative process per se determines a series of events that regulate hepatocellular sex hormone receptor status independent of extrahepatic stimuli.
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Affiliation(s)
- D Kahn
- Department of Medicine, University of Pittsburgh, Pennsylvania 15261
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