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Cytoplasmic Localization of RXRα Determines Outcome in Breast Cancer. Cancers (Basel) 2021; 13:cancers13153756. [PMID: 34359656 PMCID: PMC8345077 DOI: 10.3390/cancers13153756] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 07/20/2021] [Accepted: 07/21/2021] [Indexed: 12/24/2022] Open
Abstract
Simple Summary Considering the immense development of today’s therapeutic approaches in oncology towards customized therapy, this study aimed to assess the prognostic value of nuclear versus cytoplasmic retinoid X receptor α (RXRα) expression in breast cancer. Our results demonstrate that RXRα expression may have different roles in tumorigenesis according to its subcellular localization. This study strengthens the need for further research on the behavior of RXRα, depending on its intracellular localization. Abstract The aim of this retrospective study was to assess the prognostic value of cytoplasmic versus nuclear RXRα expression in breast cancer (BC) tissue samples and to correlate the results with clinicopathological parameters. In 319 BC patients, the expression of RXRα was evaluated via immunohistochemistry. Prognosis-determining aspects were calculated through uni- and multivariate analyses. Correlation analysis revealed a trend association with nuclear RXRα expression regarding an improved overall survival (OS) (p = 0.078), whereas cytoplasmic RXRα expression was significantly correlated with a poor outcomes in terms of both OS (p = 0.038) and disease-free survival (DFS) (p = 0.037). Strengthening these results, cytoplasmic RXRα was found to be an independent marker for DFS (p = 0.023), when adjusted to clinicopathological parameters, whereas nuclear RXRα expression was positively associated with lower TNM-staging, i.e., pT (p = 0.01), pN (p = 0.029) and pM (p = 0.001). Additionally, cytoplasmic RXRα expression was positively associated with a higher histopathological tumor grading (p = 0.02). Cytoplasmic RXRα was also found to be a negative prognosticator for Her-2neu-negative and triple-negative patients. Altogether, these findings support the hypothesis that the subcellular localization of RXRα plays an important role in carcinogenesis and the prognosis of BC. The expression of cytoplasmic RXRα is correlated with a more aggressive course of the disease, whereas nuclear RXRα expression appears to be a protective factor. These data may help to identify high-risk BC subgroups in order to find possible specific options in targeted tumor therapy.
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Zehni AZ, Batz F, Vattai A, Kaltofen T, Schrader S, Jacob SN, Mumm JN, Heidegger HH, Ditsch N, Mahner S, Jeschke U, Vilsmaier T. The Prognostic Impact of Retinoid X Receptor and Thyroid Hormone Receptor alpha in Unifocal vs. Multifocal/Multicentric Breast Cancer. Int J Mol Sci 2021; 22:957. [PMID: 33478016 PMCID: PMC7835829 DOI: 10.3390/ijms22020957] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 01/11/2021] [Accepted: 01/18/2021] [Indexed: 12/24/2022] Open
Abstract
The aim of this study was to assess the prognostic value of the steroid hormone receptor expression, counting the retinoid X receptor (RXR) and thyroid hormone receptors (THRs), on the two different breast cancer (BC) entities: multifocal/multicentric versus unifocal. The overall and disease-free survival were considered as the prognosis determining aspects and analyzed by uni- and multi-variate analysis. Furthermore, histopathological grading and TNM staging (T = tumor size, N = lymph node involvement, M = distant metastasis) were examined in relation to RXR and THRs expression. A retrospective statistical analysis was carried out on survival-related events in a series of 319 sporadic BC patients treated at the Department of Gynecology and Obstetrics at the Ludwig-Maximillian's University in Munich between 2000 and 2002. The expression of RXR and THRs, including its two major isoforms THRα1 and THRα2, was analyzed by immunohistochemistry and showed to have a significant correlation for both BC entities in regard to survival analysis. Patients with multifocal/multicentric BC were exposed to a significantly worse disease-free survival (DFS) when expressing RXR. Patients with unifocal BC showed a significantly worse DFS when expressing THRα1. In contrast, a statistically significant positive association between THRα2 expression and enhanced DFS in multifocal/multicentric BC was shown. Especially the RXR expression in multifocal/multicentric BC was found to play a remarkably contradictory role for BC prognosis. The findings imply the need for a critical review of possible molecular therapies targeting steroid hormone receptors in BC treatment. Our results strengthen the need to further investigate the behavior of the nuclear receptor family, especially in relation to BC focality.
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Affiliation(s)
- Alaleh Zati Zehni
- Department of Obstetrics and Gynecology, University Hospital Munich, LMU, 80337 Munich, Germany; (A.Z.Z.); (F.B.); (A.V.); (T.K.); (S.S.); (H.H.H.); (N.D.); (S.M.); (T.V.)
| | - Falk Batz
- Department of Obstetrics and Gynecology, University Hospital Munich, LMU, 80337 Munich, Germany; (A.Z.Z.); (F.B.); (A.V.); (T.K.); (S.S.); (H.H.H.); (N.D.); (S.M.); (T.V.)
| | - Aurelia Vattai
- Department of Obstetrics and Gynecology, University Hospital Munich, LMU, 80337 Munich, Germany; (A.Z.Z.); (F.B.); (A.V.); (T.K.); (S.S.); (H.H.H.); (N.D.); (S.M.); (T.V.)
| | - Till Kaltofen
- Department of Obstetrics and Gynecology, University Hospital Munich, LMU, 80337 Munich, Germany; (A.Z.Z.); (F.B.); (A.V.); (T.K.); (S.S.); (H.H.H.); (N.D.); (S.M.); (T.V.)
| | - Svenja Schrader
- Department of Obstetrics and Gynecology, University Hospital Munich, LMU, 80337 Munich, Germany; (A.Z.Z.); (F.B.); (A.V.); (T.K.); (S.S.); (H.H.H.); (N.D.); (S.M.); (T.V.)
| | - Sven-Niclas Jacob
- Department of General, Visceral, Transplant, Vascular and Thoracic Surgery, LMU, Marchioninistraße 15, 81377 Munich, Germany;
| | - Jan-Niclas Mumm
- Department of Urology, LMU, Marchioninistraße 15, 81377 Munich, Germany;
| | - Helene Hildegard Heidegger
- Department of Obstetrics and Gynecology, University Hospital Munich, LMU, 80337 Munich, Germany; (A.Z.Z.); (F.B.); (A.V.); (T.K.); (S.S.); (H.H.H.); (N.D.); (S.M.); (T.V.)
| | - Nina Ditsch
- Department of Obstetrics and Gynecology, University Hospital Munich, LMU, 80337 Munich, Germany; (A.Z.Z.); (F.B.); (A.V.); (T.K.); (S.S.); (H.H.H.); (N.D.); (S.M.); (T.V.)
- Department of Obstetrics and Gynecology, University Hospital, 86156 Augsburg, Germany
| | - Sven Mahner
- Department of Obstetrics and Gynecology, University Hospital Munich, LMU, 80337 Munich, Germany; (A.Z.Z.); (F.B.); (A.V.); (T.K.); (S.S.); (H.H.H.); (N.D.); (S.M.); (T.V.)
| | - Udo Jeschke
- Department of Obstetrics and Gynecology, University Hospital Munich, LMU, 80337 Munich, Germany; (A.Z.Z.); (F.B.); (A.V.); (T.K.); (S.S.); (H.H.H.); (N.D.); (S.M.); (T.V.)
- Department of Obstetrics and Gynecology, University Hospital, 86156 Augsburg, Germany
| | - Theresa Vilsmaier
- Department of Obstetrics and Gynecology, University Hospital Munich, LMU, 80337 Munich, Germany; (A.Z.Z.); (F.B.); (A.V.); (T.K.); (S.S.); (H.H.H.); (N.D.); (S.M.); (T.V.)
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Osz J, McEwen AG, Wolf J, Poussin-Courmontagne P, Peluso-Iltis C, Chebaro Y, Kieffer B, Rochel N. Modulation of RXR-DNA complex assembly by DNA context. Mol Cell Endocrinol 2019; 481:44-52. [PMID: 30476562 DOI: 10.1016/j.mce.2018.11.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/15/2018] [Accepted: 11/22/2018] [Indexed: 01/16/2023]
Abstract
Retinoid X Receptors (RXRs) act as dimer partners for several nuclear receptors including itself, binding to genomic DNA response elements and regulating gene transcription with cell and gene specificity. As homodimers, RXRs bind direct repeats of the half-site (A/G)G(G/T)TCA separated by 1 nucleotide (DR1) and little variability of this consensus site is observed for natural DR1s. However, these variations are responsible of the modulation of RXR receptors function through differential binding affinity and conformational changes. To further our understanding of the molecular mechanisms underlying RXR-DNA interactions, we examined how RXR DBDs bind to different DR1s using thermodynamics, X-ray crystallography and nuclear magnetic resonance (NMR) spectroscopy. We show that the half-site sequences modulate the binding cooperativity that results from the protein-protein contacts between the two DBDs. Chemical shifts perturbation NMR experiments revealed that sequence variations in half-sites induce changes that propagate from the protein-DNA interface to the dimerization interface throughout the DBD fold.
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Affiliation(s)
- Judit Osz
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Institut National de la Santé et de la Recherche Médicale (INSERM), U1258/Centre National de la Recherche Scientifique (CNRS), UMR7104/Université de Strasbourg, 67404, Illkirch, France
| | - Alastair G McEwen
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Institut National de la Santé et de la Recherche Médicale (INSERM), U1258/Centre National de la Recherche Scientifique (CNRS), UMR7104/Université de Strasbourg, 67404, Illkirch, France
| | - Justine Wolf
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Institut National de la Santé et de la Recherche Médicale (INSERM), U1258/Centre National de la Recherche Scientifique (CNRS), UMR7104/Université de Strasbourg, 67404, Illkirch, France
| | - Pierre Poussin-Courmontagne
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Institut National de la Santé et de la Recherche Médicale (INSERM), U1258/Centre National de la Recherche Scientifique (CNRS), UMR7104/Université de Strasbourg, 67404, Illkirch, France
| | - Carole Peluso-Iltis
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Institut National de la Santé et de la Recherche Médicale (INSERM), U1258/Centre National de la Recherche Scientifique (CNRS), UMR7104/Université de Strasbourg, 67404, Illkirch, France
| | - Yassmine Chebaro
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Institut National de la Santé et de la Recherche Médicale (INSERM), U1258/Centre National de la Recherche Scientifique (CNRS), UMR7104/Université de Strasbourg, 67404, Illkirch, France
| | - Bruno Kieffer
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Institut National de la Santé et de la Recherche Médicale (INSERM), U1258/Centre National de la Recherche Scientifique (CNRS), UMR7104/Université de Strasbourg, 67404, Illkirch, France.
| | - Natacha Rochel
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Institut National de la Santé et de la Recherche Médicale (INSERM), U1258/Centre National de la Recherche Scientifique (CNRS), UMR7104/Université de Strasbourg, 67404, Illkirch, France.
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Watanabe M, Kakuta H. Retinoid X Receptor Antagonists. Int J Mol Sci 2018; 19:ijms19082354. [PMID: 30103423 PMCID: PMC6121510 DOI: 10.3390/ijms19082354] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 08/05/2018] [Accepted: 08/07/2018] [Indexed: 12/18/2022] Open
Abstract
Retinoid X receptor (RXR) antagonists are not only useful as chemical tools for biological research, but are also candidate drugs for the treatment of various diseases, including diabetes and allergies, although no RXR antagonist has yet been approved for clinical use. In this review, we present a brief overview of RXR structure, function, and target genes, and describe currently available RXR antagonists, their structural classification, and their evaluation, focusing on the latest research.
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Affiliation(s)
- Masaki Watanabe
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.
| | - Hiroki Kakuta
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.
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Lin G, Zhu S, Wu Y, Song C, Wang W, Zhang Y, Chen YL, He Z. ω-3 free fatty acids and all-trans retinoic acid synergistically induce growth inhibition of three subtypes of breast cancer cell lines. Sci Rep 2017; 7:2929. [PMID: 28592877 PMCID: PMC5462805 DOI: 10.1038/s41598-017-03231-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 04/24/2017] [Indexed: 02/07/2023] Open
Abstract
All-trans retinoic acid (ATRA), one of vitamin A derivatives, shows greater growth inhibition of breast cancer cell for ER-positive than ER-negative cells, while triple negative breast cancer cell such as MDA-MB-231 cell is poorly responsive to ATRA treatment. In this study, we found that combination of ω-3 free fatty acids (ω-3 FFAs) and ATRA exhibited synergistic inhibition of cell growth in three subtypes (ER+ MCF7, HER2+ SK-BR-3, Triple negative HCC1806 and MDA-MB-231 cells) of human breast cancer cell lines. The combined treatment of ω-3 FFAs and ATRA resulted in cell cycle arrest. ω-3 FFAs combined with ATRA synergistically provoked cell apoptosis via the caspase signals but not p53. These findings suggest that combined chemotherapy of ω-3 FFAs with ATRA is beneficial for improvement of ATRA sensitivity in breast cancer cells.
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Affiliation(s)
- Guangxiao Lin
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, 214122, China.,Synergistic Innovation Center for Food Safety and Nutrition, Jiangnan University, Wuxi, 214122, China
| | - Shenglong Zhu
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, 214122, China.,Synergistic Innovation Center for Food Safety and Nutrition, Jiangnan University, Wuxi, 214122, China
| | - Yikuan Wu
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, 214122, China.,Synergistic Innovation Center for Food Safety and Nutrition, Jiangnan University, Wuxi, 214122, China
| | - Ci Song
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, 214122, China.,Synergistic Innovation Center for Food Safety and Nutrition, Jiangnan University, Wuxi, 214122, China
| | - Wanjing Wang
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, 214122, China.,Synergistic Innovation Center for Food Safety and Nutrition, Jiangnan University, Wuxi, 214122, China
| | - Yuan Zhang
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, 214122, China.,Synergistic Innovation Center for Food Safety and Nutrition, Jiangnan University, Wuxi, 214122, China
| | - Yue-Lei Chen
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, P.R. China.
| | - Zhao He
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, 214122, China. .,Synergistic Innovation Center for Food Safety and Nutrition, Jiangnan University, Wuxi, 214122, China. .,School of Medicine, Jiangnan University, Wuxi, 214122, China.
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Menéndez-Gutiérrez MP, Ricote M. The multi-faceted role of retinoid X receptor in bone remodeling. Cell Mol Life Sci 2017; 74:2135-2149. [PMID: 28105491 PMCID: PMC11107715 DOI: 10.1007/s00018-017-2458-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 12/20/2016] [Accepted: 01/04/2017] [Indexed: 02/07/2023]
Abstract
Retinoid X receptors (RXRs) form a unique subclass within the nuclear receptor (NR) superfamily of ligand-dependent transcription factors. RXRs are obligatory partners for a number of other NRs, placing RXRs in a coordinating role at the crossroads of multiple signaling pathways. In addition, RXRs can function as self-sufficient homodimers. Recent advances have revealed RXRs as novel regulators of osteoclastogenesis and bone remodeling. This review outlines the versatility of RXR action in the control of transcription of bone-forming osteoblasts and bone-resorbing osteoclasts, both through heterodimerization with other NRs and through RXR homodimerization. RXR signaling is currently a major therapeutic target and, therefore, knowledge of how RXR signaling affects bone remodeling creates enormous potential for the translation of basic research findings into successful clinical therapies to increase bone mass and improve bone quality.
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Affiliation(s)
- María P Menéndez-Gutiérrez
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Melchor Fernández Almagro, 3, 28029, Madrid, Spain
| | - Mercedes Ricote
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Melchor Fernández Almagro, 3, 28029, Madrid, Spain.
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Heublein S, Mayr D, Meindl A, Kircher A, Jeschke U, Ditsch N. Vitamin D receptor, Retinoid X receptor and peroxisome proliferator-activated receptor γ are overexpressed in BRCA1 mutated breast cancer and predict prognosis. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2017; 36:57. [PMID: 28427429 PMCID: PMC5399435 DOI: 10.1186/s13046-017-0517-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 03/17/2017] [Indexed: 01/25/2023]
Abstract
Background BRCA1 mutated breast cancers are commonly diagnosed as negative for classical hormone receptors i.e. estrogen receptor, progesterone receptor and/or Her2. Due to these common targets being absent the application of anti-endocrine therapies is rather limited and a certain focus has been set on discovering alternative target molecules. We recently highlighted thyroid hormone receptors (TRs) to predict prognosis in breast cancer patients that had been diagnosed a BRCA1 germline mutation. Vitamin D Receptor (VDR), Retinoid X Receptor (RXR) and Peroxisome Proliferator-activated Receptor γ (PPARγ) are known to interact with TRs by forming functional heterodimers. Whether VDR, RXR or PPARγ are expressed in BRCA1 mutated breast cancer or may even be present in case of triple negativity is not known. Hence the current study aimed to investigate VDR, RXR and PPARγ in BRCA1mut breast cancer and to test whether any of the three may be associated with clinico-pathological criteria including overall survival. Methods This study analyzed VDR, RXR and PPARγ by immunohistochemistry in BRCA1 associated (n = 38) and sporadic breast cancer (n = 79). Receptors were quantified by applying an established scoring system (IR-score) and were tested for association with clinico-pathological variables. Results VDR, RXR and PPARγ were detected in over 90% of triple negative BRCA1mut breast cancer and were significantly (VDR: p < 0.001, RXR: p = 0.010, PPARγ: p < 0.001) overexpressed in BRCA1 mutated as compared to sporadic cancer cases. VDR and RXR positivity predicted prolonged overall survival only in BRCA1 mutated cases while such association was not observed in sporadic breast cancer. Conclusions In conclusion, this is the first study to describe VDR, RXR and PPARγ in BRCA1 mutated breast cancer. Based on the data presented here these receptors may be hypothesized to potentially evolve as interesting markers or even targets in hereditary breast cancer. However, independent studies are indispensable thus to confirm this hypothesis. Electronic supplementary material The online version of this article (doi:10.1186/s13046-017-0517-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sabine Heublein
- Department of Obstetrics and Gynaecology - National Center for Tumor Diseases (NCT), Heidelberg University Hospital, Heidelberg, Germany. .,Department of Obstetrics and Gynecology, Ludwig-Maximilians-University of Munich, Munich, Germany.
| | - Doris Mayr
- Department of Pathology, Ludwig-Maximilians-University of Munich, Munich, Germany
| | - Alfons Meindl
- Department of Obstetrics and Gynecology, Technical University of Munich, Munich, Germany
| | - Alexandra Kircher
- Department of Internal Medicine, SLK-Kliniken Heilbronn GmbH, Heilbronn, Germany
| | - Udo Jeschke
- Department of Obstetrics and Gynecology, Ludwig-Maximilians-University of Munich, Munich, Germany
| | - Nina Ditsch
- Department of Obstetrics and Gynecology, Ludwig-Maximilians-University of Munich, Munich, Germany
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Muccio DD, Atigadda VR, Brouillette WJ, Bland KI, Krontiras H, Grubbs CJ. Translation of a Tissue-Selective Rexinoid, UAB30, to the Clinic for Breast Cancer Prevention. Curr Top Med Chem 2017; 17:676-695. [PMID: 27320329 PMCID: PMC9904082 DOI: 10.2174/1568026616666160617093604] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 03/25/2016] [Accepted: 03/25/2016] [Indexed: 11/22/2022]
Abstract
This review focuses on our efforts to translate a low-toxicity retinoid X receptor-selective agonist, UAB30, to the clinic for the prevention of breast cancers. The review is divided into several sections. First, the current status of breast cancer prevention is discussed. Next, preclinical studies are presented that support translation of rexinoids to the clinic for cancer prevention. While current FDAapproved retinoids and rexinoids demonstrate profound effects in treating cancers, they lack sufficient safety for long term use in the high risk population that is otherwise disease free. The review stresses the need to identify cancer preventive drugs that are effective and safe in order to gain wide use in the clinic. Due to the heterogeneity of the disease, UAB30 is evaluated for the prevention of ER-positive and ER-negative mammary cancers. Since selective estrogen receptor modulators and aromatase inhibitors are used clinically to prevent and treat ER-positive breast cancers, preclinical studies also must demonstrate efficacy of UAB30 in combination with existing drugs under use in the clinic. To support an Investigational New Drug Application to the FDA, data on pharmacology and toxicity as well as mutagenicity is gathered prior to human trials. The review concludes with a discussion of the outcomes of human Phase 0/1 clinical trials that determine the safety and pharmacology of UAB30. These studies are essential before this agent is evaluated for efficacy in phase 2 trials. Success in phase 2 evaluation is critical before long-term and costly phase 3 trials are undertaken. The lack of surrogate biomarkers as endpoints for phase 2 evaluation of rexinoid preventive agents is discussed.
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Affiliation(s)
- Donald D. Muccio
- Department of Chemistry, University of Alabama at Birmingham, Birmingham Alabama 35294 USA
| | - Venkatram R Atigadda
- Department of Chemistry, University of Alabama at Birmingham, Birmingham Alabama 35294 USA
| | - Wayne J Brouillette
- Department of Chemistry, University of Alabama at Birmingham, Birmingham Alabama 35294 USA
| | - Kirby I Bland
- Department of Surgery, University of Alabama at Birmingham, Birmingham Alabama 35294 USA
| | - Helen Krontiras
- Department of Surgery, University of Alabama at Birmingham, Birmingham Alabama 35294 USA
| | - Clinton J Grubbs
- Department of Surgery, University of Alabama at Birmingham, Birmingham Alabama 35294 USA
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Sun J, Narayanasamy S, Curley RW, Harrison EH. β-Apo-13-carotenone regulates retinoid X receptor transcriptional activity through tetramerization of the receptor. J Biol Chem 2014; 289:33118-24. [PMID: 25324544 DOI: 10.1074/jbc.m114.610501] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Retinoid X receptor (RXRα) is activated by 9-cis-retinoic acid (9cRA) and regulates transcription as a homodimer or as a heterodimer with other nuclear receptors. We have previously demonstrated that β-apo-13-carotenone, an eccentric cleavage product of β-carotene, antagonizes the activation of RXRα by 9cRA in mammalian cells overexpressing this receptor. However, the molecular mechanism of β-apo-13-carotenone's modulation on the transcriptional activity of RXRα is not understood and is the subject of this report. We performed transactivation assays using full-length RXRα and reporter gene constructs (RXRE-Luc) transfected into COS-7 cells, and luciferase activity was examined. β-Apo-13-carotenone was compared with the RXRα antagonist UVI3003. The results showed that both β-apo-13-carotenone and UVI3003 shifted the dose-dependent RXRα activation by 9cRA. In contrast, the results of assays using a hybrid Gal4-DBD:RXRαLBD receptor reporter cell assay that detects 9cRA-induced coactivator binding to the ligand binding domain demonstrated that UVI3003 significantly inhibited 9cRA-induced coactivator binding to RXRαLBD, but β-apo-13-carotenone did not. However, both β-apo-13-carotenone and UVI3003 inhibited 9-cRA induction of caspase 9 gene expression in the mammary carcinoma cell line MCF-7. To resolve this apparent contradiction, we investigated the effect of β-apo-13-carotenone on the oligomeric state of purified recombinant RXRαLBD. β-Apo-13-carotenone induces tetramerization of the RXRαLBD, although UVI3003 had no effect on the oligomeric state. These observations suggest that β-apo-13-carotenone regulates RXRα transcriptional activity by inducing the formation of the "transcriptionally silent" RXRα tetramer.
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Affiliation(s)
- Jian Sun
- From the Department of Human Sciences and
| | - Sureshbabu Narayanasamy
- From the Department of Human Sciences and College of Pharmacy, Ohio State University, Columbus, Ohio 43210
| | - Robert W Curley
- College of Pharmacy, Ohio State University, Columbus, Ohio 43210
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Inoue M, Tanabe H, Nakashima KI, Ishida Y, Kotani H. Rexinoids isolated from Sophora tonkinensis with a gene expression profile distinct from the synthetic rexinoid bexarotene. JOURNAL OF NATURAL PRODUCTS 2014; 77:1670-1677. [PMID: 24959987 DOI: 10.1021/np5002016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The retinoid X receptor (RXR) plays a critical role in transcriptional regulation via formation of an RXR homodimer or heterodimers with partner nuclear receptors. Despite the numerous beneficial effects, only a limited number of naturally occurring RXR agonists are known. In this report, two prenylated flavanones (1 and 2) isolated from Sophora tonkinensis were identified as new rexinoids that preferentially activated RXRs, relative to the retinoic acid receptor. The activities of 1 and 2 were the most potent among naturally occurring rexinoids, yet 2 orders of magnitude lower than the synthetic rexinoid bexarotene. Compounds 1 and 2 activated particular RXR heterodimers in a manner similar to bexarotene. A microarray assay followed by quantitative real-time polymerase chain reaction analyses on RNAs isolated from C2C12 myotubes treated with 1 or 2 demonstrated that they significantly increased mRNA levels of lipoprotein lipase, angiopoietin-like protein 4, and heme oxygenase-1. In contrast, bexarotene preferentially potentiated transcription of genes involved in lipogenesis and lipid metabolism such as sterol regulatory element-binding protein-1, fatty acid synthase, and apolipoprotein D by a liver X receptor agonist. In this study, we have demonstrated that two newly identified naturally occurring rexinoids, 1 and 2, possess properties different from bexarotene.
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Affiliation(s)
- Makoto Inoue
- Department of Pharmacology of Natural Compounds, Graduate School of Pharmaceutical Sciences, Aichi Gakuin University , 1-100 Kusumoto-cho, Chikusa-ku, Nagoya 464-8650, Japan
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Niu G, Lu L, Gan J, Zhang D, Liu J, Huang G. Dual roles of orphan nuclear receptor TR3/Nur77/NGFI-B in mediating cell survival and apoptosis. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2014; 313:219-58. [PMID: 25376494 DOI: 10.1016/b978-0-12-800177-6.00007-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
As a transcriptional factor, Nur77 has sparked interests across different research fields in recent years. A number of studies have demonstrated the functional complexity of Nur77 in mediating survival/apoptosis in a variety of cells, including tumor cells. Conflicting observations also exist in clinical reports, in that TR3 behaves like an oncogene in tumors of the GI tract, lung, and breast, that is negatively associated with tumor stage and patient prognosis; while functions as a tumor suppressor gene in malignancies of the hematological and lymphatic system, skin, and ovary whose malfunction results in carcinogenesis. This chapter summarizes the apparent opposing effects of Nur77 on cells and explicates the mechanisms that determine the functional preference of Nur77. We conclude that in addition to cell type and agent context, other factors such as cellular localization, signaling pathway, and posttranslational modification also determine the final effects of Nur77 on cells.
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Affiliation(s)
- Gengming Niu
- Department of General Surgery, Huashan Hospital, Fudan University, Shanghai, China
| | - Lei Lu
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Jun Gan
- Department of General Surgery, Huashan Hospital, Fudan University, Shanghai, China
| | - Di Zhang
- Main Library, Shanghai Jiao Tong University, Shanghai, China
| | - Jingzheng Liu
- Department of General Surgery, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Guangjian Huang
- Department of General Surgery, Huashan Hospital, Fudan University, Shanghai, China
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Boerma LJ, Xia G, Qui C, Cox BD, Chalmers MJ, Smith CD, Lobo-Ruppert S, Griffin PR, Muccio DD, Renfrow MB. Defining the communication between agonist and coactivator binding in the retinoid X receptor α ligand binding domain. J Biol Chem 2013; 289:814-26. [PMID: 24187139 DOI: 10.1074/jbc.m113.476861] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Retinoid X receptors (RXRs) are obligate partners for several other nuclear receptors, and they play a key role in several signaling processes. Despite being a promiscuous heterodimer partner, this nuclear receptor is a target of therapeutic intervention through activation using selective RXR agonists (rexinoids). Agonist binding to RXR initiates a large conformational change in the receptor that allows for coactivator recruitment to its surface and enhanced transcription. Here we reveal the structural and dynamical changes produced when a coactivator peptide binds to the human RXRα ligand binding domain containing two clinically relevant rexinoids, Targretin and 9-cis-UAB30. Our results show that the structural changes are very similar for each rexinoid and similar to those for the pan-agonist 9-cis-retinoic acid. The four structural changes involve key residues on helix 3, helix 4, and helix 11 that move from a solvent-exposed environment to one that interacts extensively with helix 12. Hydrogen-deuterium exchange mass spectrometry reveals that the dynamics of helices 3, 11, and 12 are significantly decreased when the two rexinoids are bound to the receptor. When the pan-agonist 9-cis-retinoic acid is bound to the receptor, only the dynamics of helices 3 and 11 are reduced. The four structural changes are conserved in all x-ray structures of the RXR ligand-binding domain in the presence of agonist and coactivator peptide. They serve as hallmarks for how RXR changes conformation and dynamics in the presence of agonist and coactivator to initiate signaling.
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Rőszer T, Menéndez-Gutiérrez MP, Cedenilla M, Ricote M. Retinoid X receptors in macrophage biology. Trends Endocrinol Metab 2013; 24:460-8. [PMID: 23701753 DOI: 10.1016/j.tem.2013.04.004] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 04/19/2013] [Accepted: 04/23/2013] [Indexed: 01/07/2023]
Abstract
Retinoid X receptors (RXRs) form a distinct and unique subclass within the nuclear receptor (NR) superfamily of ligand-dependent transcription factors. RXRs regulate a plethora of genetic programs, including cell differentiation, the immune response, and lipid and glucose metabolism. Recent advances reveal that RXRs are important regulators of macrophages, key players in inflammatory and metabolic disorders. This review outlines the versatility of RXR action in the control of macrophage gene transcription through its heterodimerization with other NRs or through RXR homodimerization. We also highlight the potential of RXR-controlled transcriptional programs as targets for the treatment of pathologies associated with altered macrophage function, such as atherosclerosis, insulin resistance, autoimmunity, and neurodegeneration.
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Affiliation(s)
- Tamás Rőszer
- Cardiovascular Development and Repair Department, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Melchor Fernández Almagro 3, 28029 Madrid, Spain
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Maeng S, Kim GJ, Choi EJ, Yang HO, Lee DS, Sohn YC. 9-Cis-retinoic acid induces growth inhibition in retinoid-sensitive breast cancer and sea urchin embryonic cells via retinoid X receptor α and replication factor C3. Mol Endocrinol 2012; 26:1821-35. [PMID: 22949521 DOI: 10.1210/me.2012-1104] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
There is widespread interest in defining factors and mechanisms that suppress the proliferation of cancer cells. Retinoic acid (RA) is a potent suppressor of mammary cancer and developmental embryonic cell proliferation. However, the molecular mechanisms by which 9-cis-RA signaling induces growth inhibition in RA-sensitive breast cancer and embryonic cells are not apparent. Here, we provide evidence that the inhibitory effect of 9-cis-RA on cell proliferation depends on 9-cis-RA-dependent interaction of retinoid X receptor α (RXRα) with replication factor C3 (RFC3), which is a subunit of the RFC heteropentamer that opens and closes the circular proliferating cell nuclear antigen (PCNA) clamp on DNA. An RFC3 ortholog in a sea urchin cDNA library was isolated by using the ligand-binding domain of RXRα as bait in a yeast two-hybrid screening. The interaction of RFC3 with RXRα depends on 9-cis-RA and bexarotene, but not on all-trans-RA or an RA receptor (RAR)-selective ligand. Truncation and mutagenesis experiments demonstrated that the C-terminal LXXLL motifs in both human and sea urchin RFC3 are critical for the interaction with RXRα. The transient interaction between 9-cis-RA-activated RXRα and RFC3 resulted in reconfiguration of the PCNA-RFC complex. Furthermore, we found that knockdown of RXRα or overexpression of RFC3 impairs the ability of 9-cis-RA to inhibit proliferation of MCF-7 breast cancer cells and sea urchin embryogenesis. Our results indicate that 9-cis-RA-activated RXRα suppresses the growth of RA-sensitive breast cancer and embryonic cells through RFC3.
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Affiliation(s)
- Sejung Maeng
- Department of Marine Molecular Biotechnology, College of Life Sciences, Gangneung-Wonju National University, Gangneung 210-702, Republic of Korea
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Dawson MI, Xia Z. The retinoid X receptors and their ligands. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:21-56. [PMID: 22020178 DOI: 10.1016/j.bbalip.2011.09.014] [Citation(s) in RCA: 257] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Revised: 08/23/2011] [Accepted: 09/23/2011] [Indexed: 12/12/2022]
Abstract
This chapter presents an overview of the current status of studies on the structural and molecular biology of the retinoid X receptor subtypes α, β, and γ (RXRs, NR2B1-3), their nuclear and cytoplasmic functions, post-transcriptional processing, and recently reported ligands. Points of interest are the different changes in the ligand-binding pocket induced by variously shaped agonists, the communication of the ligand-bound pocket with the coactivator binding surface and the heterodimerization interface, and recently identified ligands that are natural products, those that function as environmental toxins or drugs that had been originally designed to interact with other targets, as well as those that were deliberately designed as RXR-selective transcriptional agonists, synergists, or antagonists. Of these synthetic ligands, the general trend in design appears to be away from fully aromatic rigid structures to those containing partial elements of the flexible tetraene side chain of 9-cis-retinoic acid. This article is part of a Special Issue entitled Advances in High Density Lipoprotein Formation and Metabolism: A Tribute to John F. Oram (1945-2010).
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Affiliation(s)
- Marcia I Dawson
- Cancer Center, Sanford-Burn Medical Research Institute, 10901 North Torrey Pines Rd., La Jolla, CA 93207, USA.
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Lefebvre P, Benomar Y, Staels B. Retinoid X receptors: common heterodimerization partners with distinct functions. Trends Endocrinol Metab 2010; 21:676-83. [PMID: 20674387 DOI: 10.1016/j.tem.2010.06.009] [Citation(s) in RCA: 220] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 06/25/2010] [Accepted: 06/29/2010] [Indexed: 01/19/2023]
Abstract
Retinoid X receptors (RXRs) have been implicated in a diversity of cellular processes ranging from cellular proliferation to lipid metabolism. These pleiotropic effects stem not only from the ability of RXRs to dimerize with diverse nuclear receptors, which exert transcriptional control on specific aspects of cell biology, but also because binding of RXR ligands to heterodimers can stimulate transcriptional activation by RXR partner receptors. This signaling network is rendered more complex by the existence of different RXR isotypes (RXRα, RXRβ, RXRγ) with distinct properties that thereby modulate the transcriptional activity of RXR-containing heterodimers. This review discusses the emerging roles of RXR isotypes in the RXR signaling network and possible implications for our understanding of nuclear receptor biology and pharmacology.
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