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Branigan GL, Torrandell-Haro G, Chen S, Shang Y, Perez-Miller S, Mao Z, Padilla-Rodriguez M, Cortes-Flores H, Vitali F, Brinton RD. Breast cancer therapies reduce risk of Alzheimer's disease and promote estrogenic pathways and action in brain. iScience 2023; 26:108316. [PMID: 38026173 PMCID: PMC10663748 DOI: 10.1016/j.isci.2023.108316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 09/08/2023] [Accepted: 10/20/2023] [Indexed: 12/01/2023] Open
Abstract
Worldwide, an ever-increasing number of women are prescribed estrogen-modulating therapies (EMTs) for the treatment of breast cancer. In parallel, aging of the global population of women will contribute to risk of both breast cancer and Alzheimer's disease. To address the impact of anti-estrogen therapies on risk of Alzheimer's and neural function, we conducted medical informatic and molecular pharmacology analyses to determine the impact of EMTs on risk of Alzheimer's followed by determination of EMT estrogenic mechanisms of action in neurons. Collectively, these data provide both clinical and mechanistic data indicating that select EMTs exert estrogenic agonist action in neural tissue that are associated with reduced risk of Alzheimer's disease while simultaneously acting as effective estrogen receptor antagonists in breast.
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Affiliation(s)
- Gregory L. Branigan
- Center for Innovation in Brain Science, University of Arizona; Tucson AZ, USA
- Department of Pharmacology, University of Arizona College of Medicine; Tucson AZ, USA
- Medical Scientist Training Program, University of Arizona College of Medicine; Tucson AZ, USA
| | - Georgina Torrandell-Haro
- Center for Innovation in Brain Science, University of Arizona; Tucson AZ, USA
- Department of Pharmacology, University of Arizona College of Medicine; Tucson AZ, USA
| | - Shuhua Chen
- Center for Innovation in Brain Science, University of Arizona; Tucson AZ, USA
| | - Yuan Shang
- Center for Innovation in Brain Science, University of Arizona; Tucson AZ, USA
| | | | - Zisu Mao
- Center for Innovation in Brain Science, University of Arizona; Tucson AZ, USA
| | | | | | - Francesca Vitali
- Center for Innovation in Brain Science, University of Arizona; Tucson AZ, USA
- Center of Bioinformatics and Biostatistics, University of Arizona College of Medicine; Tucson AZ, USA
| | - Roberta Diaz Brinton
- Center for Innovation in Brain Science, University of Arizona; Tucson AZ, USA
- Department of Pharmacology, University of Arizona College of Medicine; Tucson AZ, USA
- Department of Neurology, University of Arizona College of Medicine; Tucson AZ, USA
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El Desoky ES, Taha AF, Mousa HS, Ibrahim A, Saleh MA, Abdelrady MA, Hareedy MS. Value of therapeutic drug monitoring of endoxifen in Egyptian premenopausal patients with breast cancer given tamoxifen adjuvant therapy: A pilot study. J Oncol Pharm Pract 2023; 29:1673-1686. [PMID: 36567618 DOI: 10.1177/10781552221146531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
BACKGROUND The complex metabolic profile of tamoxifen anticancer drug and polymorphism in its metabolizing enzymes particularly CYP2D6 contribute to the high-observed inter-individual variability in its main active metabolite endoxifen. Therapeutic drug monitoring of endoxifen may play a key role in optimizing tamoxifen therapy, and control of both adverse effects and cancer recurrence. This pilot study aims to assess the clinical benefits of applying endoxifen measurement during tamoxifen therapy in patients with breast cancer. METHODS Adult premenopausal breast cancer patients ≥ 18 years who received tamoxifen at a fixed dose of 20 mg daily were included. The primary endpoint was to identify the inter-subject variability in serum concentration of the drug and its metabolites especially endoxifen, through fixation of the tamoxifen dose. The secondary endpoint was to check the correlation between endoxifen metabolite concentration and the development of tamoxifen's adverse effects and cancer recurrence. RESULTS Sixty patients were included in the study with a mean age of 38.4 ± 0.6 years (range: 26-50). The mean concentration of tamoxifen and endoxifen was 181 ± 9.6 ng/mL and 31.49 ng/mL, respectively. The inter-individual variability in concentrations for the drug and its active metabolite as estimated by the coefficient of variation percentage was in 41% and 31%, respectively. Cancer recurrence was observed in a group of patients (n = 16) with an average endoxifen level of 24.48 ng/mL. Another group of patients (n = 25) developed different tamoxifen adverse effects including hot flashes, vaginal bleeding, endometrial thickness, and ovarian cysts with the average endoxifen level of 38.61 ng/mL. The rest of the patients (n = 19) who responded smoothly to the drug with no complications had an average endoxifen level of 31.37 ng/mL. Analysis of variance test showed a significant difference in endoxifen levels between the three groups (p = 0.002). CONCLUSION The measurement of the endoxifen active metabolite of tamoxifen in breast cancer patients can help dose optimization in light of the observed wide inter-individual variability in drug fixed-dose related concentration of the metabolite. Monitoring of serum concentration of endoxifen can help to reveal, reduce and control tamoxifen's adverse effects and cancer recurrence.
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Affiliation(s)
- Ehab S El Desoky
- Department of Pharmacology, Faculty of Medicine, Assiut University, Egypt
| | - Amira F Taha
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Assiut University, Egypt
| | - Heba Salah Mousa
- Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, South Valley University, Qena, Egypt
| | - Abeer Ibrahim
- Department of Medical Oncology and Hematological Malignancy, South Egypt Cancer Institute, Assiut University, Egypt
| | - Medhat A Saleh
- Department of Public Health and Community Medicine, Faculty of Medicine, Assiut University, Egypt
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Bosch F, Mulder F, Franken L, Willemsen A, Rentinck M, van den Berg P, Bakker SLD, van der Velden A, van Es N, Mathôt R, Kamphuisen PW. Effect of the P-glycoprotein inhibitor tamoxifen on edoxaban plasma levels in women with breast cancer. Thromb Res 2023; 228:46-53. [PMID: 37269716 DOI: 10.1016/j.thromres.2023.05.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Revised: 05/10/2023] [Accepted: 05/24/2023] [Indexed: 06/05/2023]
Abstract
BACKGROUND Concomitant use of P-glycoprotein inhibitors can reduce clearance of edoxaban and increase its plasma concentration. Caution is advised with simultaneous use of edoxaban and the frequently used P-glycoprotein inhibitor tamoxifen. However, pharmacokinetic data are lacking. OBJECTIVES This study aimed to assess the effect of tamoxifen on edoxaban clearance. METHODS This was a prospective, self-controlled, pharmacokinetic study in breast cancer participants starting tamoxifen. Edoxaban was given at a dose of 60 mg once daily for 4 consecutive days, first without tamoxifen and later with concomitant tamoxifen in steady-state. On day 4 of both edoxaban sequences, serial blood samples were taken. A population pharmacokinetic model was developed using nonlinear mixed effects modelling in which the effect of tamoxifen on edoxaban clearance was assessed. Additionally, mean area under the curves (AUC) were estimated. Geometric least square means (GLM) ratios were calculated and no interaction was concluded if the 90 % CI was within the 80-125 % no-effect boundaries. RESULTS Twenty-four women with breast cancer scheduled for tamoxifen were included. The median age was 56 years (IQR 51-63). The average edoxaban clearance was 32.0 L/h (95 % CI, 11.1-35.0 L/h). There was no effect of tamoxifen on edoxaban clearance, with a fraction of 100 % (95 % CI 92-108) compared to clearance without tamoxifen. The mean AUCs were 1923 ng*h/ml (SD 695) without tamoxifen and 1947 ng*h/ml (SD 595) with tamoxifen (GLM-ratio 100.4; 90 % CI 98.6-102.2). CONCLUSIONS Concomitant use of the P-glycoprotein inhibitor tamoxifen does not lead to reduced clearance of edoxaban in patients with breast cancer.
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Affiliation(s)
- Floris Bosch
- Department of Internal Medicine, Tergooi Medical Center, Hilversum, the Netherlands; Amsterdam UMC location University of Amsterdam, Department of Vascular Medicine, Amsterdam, the Netherlands; Amsterdam Cardiovascular Sciences, Pulmonary Hypertension & Thrombosis, Amsterdam, the Netherlands.
| | - Frits Mulder
- Department of Internal Medicine, Tergooi Medical Center, Hilversum, the Netherlands; Amsterdam UMC location University of Amsterdam, Department of Vascular Medicine, Amsterdam, the Netherlands; Amsterdam Cardiovascular Sciences, Pulmonary Hypertension & Thrombosis, Amsterdam, the Netherlands
| | - Linda Franken
- Department of Hospital Pharmacy - Clinical Pharmacology, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Annelieke Willemsen
- Department of Internal Medicine, Tergooi Medical Center, Hilversum, the Netherlands
| | - Marjolein Rentinck
- Department of Internal Medicine, Tergooi Medical Center, Hilversum, the Netherlands
| | - Pieter van den Berg
- Department of Internal Medicine, Tergooi Medical Center, Hilversum, the Netherlands
| | | | - Ankie van der Velden
- Department of Internal Medicine, Tergooi Medical Center, Hilversum, the Netherlands
| | - Nick van Es
- Amsterdam UMC location University of Amsterdam, Department of Vascular Medicine, Amsterdam, the Netherlands; Amsterdam Cardiovascular Sciences, Pulmonary Hypertension & Thrombosis, Amsterdam, the Netherlands
| | - Ron Mathôt
- Department of Hospital Pharmacy - Clinical Pharmacology, Amsterdam University Medical Center, Amsterdam, the Netherlands
| | - Pieter W Kamphuisen
- Department of Internal Medicine, Tergooi Medical Center, Hilversum, the Netherlands; Amsterdam UMC location University of Amsterdam, Department of Vascular Medicine, Amsterdam, the Netherlands; Amsterdam Cardiovascular Sciences, Pulmonary Hypertension & Thrombosis, Amsterdam, the Netherlands
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Galvano E, Pandit H, Sepulveda J, Ng CAS, Becher MK, Mandelblatt JS, Van Dyk K, Rebeck GW. Behavioral and transcriptomic effects of the cancer treatment tamoxifen in mice. Front Neurosci 2023; 17:1068334. [PMID: 36845433 PMCID: PMC9951777 DOI: 10.3389/fnins.2023.1068334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 01/24/2023] [Indexed: 02/12/2023] Open
Abstract
Introduction Tamoxifen is a common treatment for estrogen receptor-positive breast cancer. While tamoxifen treatment is generally accepted as safe, there are concerns about adverse effects on cognition. Methods We used a mouse model of chronic tamoxifen exposure to examine the effects of tamoxifen on the brain. Female C57/BL6 mice were exposed to tamoxifen or vehicle control for six weeks; brains of 15 mice were analyzed for tamoxifen levels and transcriptomic changes, and an additional 32 mice were analyzed through a battery of behavioral tests. Results Tamoxifen and its metabolite 4-OH-tamoxifen were found at higher levels in the brain than in the plasma, demonstrating the facile entry of tamoxifen into the CNS. Behaviorally, tamoxifen-exposed mice showed no impairment in assays related to general health, exploration, motor function, sensorimotor gating, and spatial learning. Tamoxifen-treated mice showed a significantly increased freezing response in a fear conditioning paradigm, but no effects on anxiety measures in the absence of stressors. RNA sequencing analysis of whole hippocampi showed tamoxifen-induced reductions in gene pathways related to microtubule function, synapse regulation, and neurogenesis. Discussion These findings of the effects of tamoxifen exposure on fear conditioning and on gene expression related to neuronal connectivity suggest that there may be CNS side effects of this common breast cancer treatment.
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Affiliation(s)
- Elena Galvano
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC, United States
| | - Harshul Pandit
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC, United States
| | - Jordy Sepulveda
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States
| | - Christi Anne S. Ng
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC, United States
| | - Melanie K. Becher
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC, United States
| | - Jeanne S. Mandelblatt
- Department of Oncology, Georgetown Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, United States
| | - Kathleen Van Dyk
- Department of Psychiatry, UCLA Semel Institute for Neuroscience and Human Behavior, Los Angeles, CA, United States
| | - G. William Rebeck
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC, United States
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Khattak MA, Iqbal Z, Fazli N, Khan FU, Khan S, Gohar S, Sakhi M, Iqbal M, Pervez S. Using the Design of Experiments for Development, Validation, and Optimization of HPLC-UV Assay of Tamoxifen Citrate in Polymeric Nanoparticles. Pharm Chem J 2022. [DOI: 10.1007/s11094-022-02789-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Langendonk M, de Jong MRW, Smit N, Seiler J, Reitsma B, Ammatuna E, Glaudemans AWJM, van den Berg A, Huls GA, Visser L, van Meerten T. Identification of the estrogen receptor beta as a possible new tamoxifen-sensitive target in diffuse large B-cell lymphoma. Blood Cancer J 2022; 12:36. [PMID: 35256592 PMCID: PMC8901714 DOI: 10.1038/s41408-022-00631-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 01/21/2022] [Accepted: 01/27/2022] [Indexed: 01/14/2023] Open
Abstract
Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoma subtype. Despite the proven efficacy of combined immunochemotherapy (R-CHOP) in the majority of patients, ~40% of DLBCL patients do not respond or will relapse and consequently have a very poor prognosis. The development of targeted therapies has not improved patient survival, underscoring the need for new treatment approaches. Using an unbiased genome-wide CD20 guilt-by-association approach in more than 1800 DLBCL patients, we previously identified the estrogen receptor beta (ERβ) as a new target in DLBCL. Here, we demonstrate that ERβ is expressed at significantly higher levels in DLBCL compared to normal B cells, and ERβ plays a role in the protection against apoptosis in DLBCL. Targeting of the ERβ with the selective estrogen receptor modulator tamoxifen reduces cell viability in all tested DLBCL cell lines. Tamoxifen-induced cell death was significantly decreased in an ERβ knock-out cell line. The activity of tamoxifen was confirmed in a xenograft human lymphoma model, as tumor growth decreased, and survival significantly improved. Finally, tamoxifen-treated breast cancer (BC) patients showed a significantly reduced risk of 38% for DLBCL compared to BC patients who did not receive tamoxifen. Our findings provide a rationale to investigate tamoxifen, a hormonal drug with a good safety profile, in DLBCL patients.
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Affiliation(s)
- Myra Langendonk
- University of Groningen, University Medical Center Groningen, Department of Hematology, Groningen, the Netherlands
| | - Mathilde R W de Jong
- University of Groningen, University Medical Center Groningen, Department of Hematology, Groningen, the Netherlands
| | - Nienke Smit
- University of Groningen, University Medical Center Groningen, Department of Hematology, Groningen, the Netherlands
| | - Jonas Seiler
- University of Groningen, ERIBA, Genomic Instability in Development and Disease, Groningen, the Netherlands
| | - Bart Reitsma
- University of Groningen, University Medical Center Groningen, Department of Hematology, Groningen, the Netherlands
| | - Emanuele Ammatuna
- University of Groningen, University Medical Center Groningen, Department of Hematology, Groningen, the Netherlands
| | - Andor W J M Glaudemans
- University of Groningen, University Medical center Groningen, Department of Nuclear Medicine and Molecular Imaging, Groningen, The Netherlands
| | - Anke van den Berg
- University of Groningen, University Medical Center Groningen, Department of Pathology and Medical Biology, Groningen, the Netherlands
| | - Gerwin A Huls
- University of Groningen, University Medical Center Groningen, Department of Hematology, Groningen, the Netherlands
| | - Lydia Visser
- University of Groningen, University Medical Center Groningen, Department of Pathology and Medical Biology, Groningen, the Netherlands
| | - Tom van Meerten
- University of Groningen, University Medical Center Groningen, Department of Hematology, Groningen, the Netherlands.
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Slanař O, Hronová K, Bartošová O, Šíma M. Recent advances in the personalized treatment of estrogen receptor-positive breast cancer with tamoxifen: a focus on pharmacogenomics. Expert Opin Drug Metab Toxicol 2020; 17:307-321. [PMID: 33320718 DOI: 10.1080/17425255.2021.1865310] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Introduction: Tamoxifen is still an important drug in hormone-dependent breast cancer therapy. Personalization of its clinical use beyond hormone receptor positivity could improve the substantial variability of the treatment response.Areas covered: The overview of the current evidence for the treatment personalization using therapeutic drug monitoring, or using genetic biomarkers including CYP2D6 is provided. Although many studies focused on the PK aspects or the impact of CYP2D6 variability the translation into clinical routine is not clearly defined due to the inconsistent clinical outcome data.Expert opinion: We believe that at least the main candidate factors, i.e. CYP2D6 polymorphism, CYP2D6 inhibition, endoxifen serum levels may become important predictors of clinical relevance for tamoxifen treatment personalization in the future. To achieve this aim, however, further research should take into consideration more precise characterization of the disease, epigenetic factors and also utilize an appropriately powered multifactorial approach instead of a single gene evaluating studies.
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Affiliation(s)
- Ondřej Slanař
- Department of Pharmacology, Charles University and General University Hospital, Prague, Czech Republic
| | - Karolína Hronová
- Department of Pharmacology, Charles University and General University Hospital, Prague, Czech Republic
| | - Olga Bartošová
- Department of Pharmacology, Charles University and General University Hospital, Prague, Czech Republic
| | - Martin Šíma
- Department of Pharmacology, Charles University and General University Hospital, Prague, Czech Republic
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8
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Fotoohi AK, Karim H, Lafolie P, Pohanka A, Östervall J, Hatschek T, Vitols S. Pronounced Interindividual But Not Intraindividual Variation in Tamoxifen and Metabolite Levels in Plasma During Adjuvant Treatment of Women With Early Breast Cancer. Ther Drug Monit 2016; 38:239-45. [DOI: 10.1097/ftd.0000000000000257] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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9
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Intratumor heterogeneity and its impact on drug distribution and sensitivity. Clin Pharmacol Ther 2014; 96:224-38. [PMID: 24827540 DOI: 10.1038/clpt.2014.105] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 05/07/2014] [Indexed: 01/04/2023]
Abstract
We provide an overview of the available information on the distribution of chemotherapeutics in human tumors, highlighting the progress made to assess the heterogeneity of drug concentrations in relation to the complex neoplastic tissue using novel analytical methods, e.g., mass spectrometry imaging. The increase in interstitial fluid pressure due to abnormal vascularization and stiffness of tumor stroma explains the variable and heterogeneous drug concentrations. Therapeutic strategies to enhance tumor drug distribution, thus possibly increasing efficacy, are discussed.
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Extraction of tamoxifen and its metabolites from formalin-fixed, paraffin-embedded tissues: an innovative quantitation method using liquid chromatography and tandem mass spectrometry. Cancer Chemother Pharmacol 2014; 73:475-84. [PMID: 24414550 PMCID: PMC3931943 DOI: 10.1007/s00280-013-2346-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 10/31/2013] [Indexed: 12/29/2022]
Abstract
PURPOSE Tamoxifen is a key therapeutic option for breast cancer treatment. Understanding its complex metabolism and pharmacokinetics is important for dose optimization. We examined the possibility of utilizing archival formalin-fixed paraffin-embedded (FFPE) tissue as an alternative sample source for quantification since well-annotated retrospective samples were always limited. METHODS Six 15 μm sections of FFPE tissues were deparaffinized with xylene and purified using solid-phase extraction. Tamoxifen and its metabolites were separated and detected by liquid chromatography-tandem mass spectrometry using multiple-reaction monitoring. RESULTS This method was linear between 0.4 and 200 ng/g for 4-hydroxy-tamoxifen and endoxifen, and 4-2,000 ng/g for tamoxifen and N-desmethyl-tamoxifen. Inter- and intra-assay precisions were <9 %, and mean accuracies ranged from 81 to 106 %. Extraction recoveries were between 83 and 88 %. The validated method was applied to FFPE tissues from two groups of patients, who received 20 mg/day of tamoxifen for >6 months, and were classified into breast tumor recurrence and non-recurrence. Our preliminary data show that levels of tamoxifen metabolites were significantly lower in patients with recurrent cancer, suggesting that inter-individual variability in tamoxifen metabolism might partly account for the development of cancer recurrence. Nevertheless, other causes such as non-compliance or stopping therapy of tamoxifen could possibly lead to the concentration differences. CONCLUSIONS The ability to successfully study tamoxifen metabolism in such tissue samples will rapidly increase our knowledge of how tamoxifen's action, metabolism and tissue distribution contribute to breast cancer control. However, larger population studies are required to understand the underlying mechanism of tamoxifen metabolism for optimization of its treatment.
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Asp ML, Martindale JJ, Metzger JM. Direct, differential effects of tamoxifen, 4-hydroxytamoxifen, and raloxifene on cardiac myocyte contractility and calcium handling. PLoS One 2013; 8:e78768. [PMID: 24205315 PMCID: PMC3811994 DOI: 10.1371/journal.pone.0078768] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 09/15/2013] [Indexed: 12/14/2022] Open
Abstract
Tamoxifen (Tam), a selective estrogen receptor modulator, is in wide clinical use for the treatment and prevention of breast cancer. High Tam doses have been used for treatment of gliomas and cancers with multiple drug resistance, but long QT Syndrome is a side effect. Tam is also used experimentally in mice for inducible gene knockout in numerous tissues, including heart; however, the potential direct effects of Tam on cardiac myocyte mechanical function are not known. The goal of this study was to determine the direct, acute effects of Tam, its active metabolite 4-hydroxytamoxifen (4OHT), and related drug raloxifene (Ral) on isolated rat cardiac myocyte mechanical function and calcium handling. Tam decreased contraction amplitude, slowed relaxation, and decreased Ca2+ transient amplitude. Effects were primarily observed at 5 and 10 μM Tam, which is relevant for high dose Tam treatment in cancer patients as well as Tam-mediated gene excision in mice. Myocytes treated with 4OHT responded similarly to Tam-treated cells with regard to both contractility and calcium handling, suggesting an estrogen-receptor independent mechanism is responsible for the effects. In contrast, Ral increased contraction and Ca2+ transient amplitudes. At 10 μM, all drugs had a time-dependent effect to abolish cellular contraction. In conclusion, Tam, 4OHT, and Ral adversely and differentially alter cardiac myocyte contractility and Ca2+ handling. These findings have important implications for understanding the Tam-induced cardiomyopathy in gene excision studies and may be important for understanding effects on cardiac performance in patients undergoing high-dose Tam therapy.
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Affiliation(s)
- Michelle L Asp
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, Minnesota, United States of America
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Dorchies OM, Reutenauer-Patte J, Dahmane E, Ismail HM, Petermann O, Patthey- Vuadens O, Comyn SA, Gayi E, Piacenza T, Handa RJ, Décosterd LA, Ruegg UT. The anticancer drug tamoxifen counteracts the pathology in a mouse model of duchenne muscular dystrophy. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 182:485-504. [PMID: 23332367 DOI: 10.1016/j.ajpath.2012.10.018] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Revised: 09/17/2012] [Accepted: 10/07/2012] [Indexed: 12/18/2022]
Abstract
Duchenne muscular dystrophy (DMD) is a severe disorder characterized by progressive muscle wasting,respiratory and cardiac impairments, and premature death. No treatment exists so far, and the identification of active substances to fight DMD is urgently needed. We found that tamoxifen, a drug used to treat estrogen-dependent breast cancer, caused remarkable improvements of muscle force and of diaphragm and cardiac structure in the mdx(5Cv) mouse model of DMD. Oral tamoxifen treatment from 3 weeks of age for 15 months at a dose of 10 mg/kg/day stabilized myofiber membranes, normalized whole body force, and increased force production and resistance to repeated contractions of the triceps muscle above normal values. Tamoxifen improved the structure of leg muscles and diminished cardiac fibrosis by~ 50%. Tamoxifen also reduced fibrosis in the diaphragm, while increasing its thickness,myofiber count, and myofiber diameter, thereby augmenting by 72% the amount of contractile tissue available for respiratory function. Tamoxifen conferred a markedly slower phenotype to the muscles.Tamoxifen and its metabolites were present in nanomolar concentrations in plasma and muscles,suggesting signaling through high-affinity targets. Interestingly, the estrogen receptors ERa and ERb were several times more abundant in dystrophic than in normal muscles, and tamoxifen normalized the relative abundance of ERb isoforms. Our findings suggest that tamoxifen might be a useful therapy for DMD.
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MESH Headings
- Animals
- Antineoplastic Agents/pharmacology
- Antineoplastic Agents/therapeutic use
- Behavior, Animal/drug effects
- Biomarkers/metabolism
- Biomechanical Phenomena/drug effects
- Body Weight/drug effects
- Creatine Kinase/blood
- Diaphragm/pathology
- Diaphragm/physiopathology
- Disease Models, Animal
- Feeding Behavior/drug effects
- Fibrosis
- Mice
- Muscle Contraction/drug effects
- Muscle Fibers, Skeletal/drug effects
- Muscle Fibers, Skeletal/pathology
- Muscular Dystrophy, Animal/blood
- Muscular Dystrophy, Animal/drug therapy
- Muscular Dystrophy, Animal/pathology
- Muscular Dystrophy, Animal/physiopathology
- Muscular Dystrophy, Duchenne/blood
- Muscular Dystrophy, Duchenne/drug therapy
- Muscular Dystrophy, Duchenne/pathology
- Muscular Dystrophy, Duchenne/physiopathology
- Myocardium/pathology
- Organ Size/drug effects
- Receptors, Estrogen/metabolism
- Tamoxifen/blood
- Tamoxifen/pharmacology
- Tamoxifen/therapeutic use
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Affiliation(s)
- Olivier M Dorchies
- Department of Pharmacology, University of Geneva and University of Lausanne, Geneva, Switzerland.
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Determination of clinically therapeutic endoxifen concentrations based on efficacy from human MCF7 breast cancer xenografts. Breast Cancer Res Treat 2013; 139:61-9. [DOI: 10.1007/s10549-013-2530-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 04/06/2013] [Indexed: 10/26/2022]
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Phytoestrogens in menopausal supplements induce ER-dependent cell proliferation and overcome breast cancer treatment in an in vitro breast cancer model. Toxicol Appl Pharmacol 2013; 269:132-40. [PMID: 23541764 DOI: 10.1016/j.taap.2013.03.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Accepted: 03/18/2013] [Indexed: 10/27/2022]
Abstract
Breast cancer treatment by the aromatase inhibitor Letrozole (LET) or Selective Estrogen Receptor Modulator Tamoxifen (TAM) can result in the onset of menopausal symptoms. Women often try to relieve these symptoms by taking menopausal supplements containing high levels of phytoestrogens. However, little is known about the potential interaction between these supplements and breast cancer treatment, especially aromatase inhibitors. In this study, interaction of phytoestrogens with the estrogen receptor alpha and TAM action was determined in an ER-reporter gene assay (BG1Luc4E2 cells) and human breast epithelial tumor cells (MCF-7). Potential interactions with aromatase activity and LET were determined in human adrenocorticocarcinoma H295R cells. We also used the previously described H295R/MCF-7 co-culture model to study interactions with steroidogenesis and tumor cell proliferation. In this model, genistein (GEN), 8-prenylnaringenin (8PN) and four commercially available menopausal supplements all induced ER-dependent tumor cell proliferation, which could not be prevented by physiologically relevant LET and 4OH-TAM concentrations. Differences in relative effect potencies between the H295R/MCF-7 co-culture model and ER-activation in BG1Luc4E2 cells, were due to the effects of the phytoestrogens on steroidogenesis. All tested supplements and GEN induced aromatase activity, while 8PN was a strong aromatase inhibitor. Steroidogenic profiles upon GEN and 8PN exposure indicated a strong inhibitory effect on steroidogenesis in H295R cells and H295R/MCF-7 co-cultures. Based on our in vitro data we suggest that menopausal supplement intake during breast cancer treatment should better be avoided, at least until more certainty regarding the safety of supplemental use in breast cancer patients can be provided.
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Agudelo D, Sanyakamdhorn S, Nafisi S, Tajmir-Riahi HA. Transporting antitumor drug tamoxifen and its metabolites, 4-hydroxytamoxifen and endoxifen by chitosan nanoparticles. PLoS One 2013; 8:e60250. [PMID: 23527310 PMCID: PMC3603901 DOI: 10.1371/journal.pone.0060250] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 02/24/2013] [Indexed: 12/12/2022] Open
Abstract
Synthetic and natural polymers are often used as drug delivery systems in vitro and in vivo. Biodegradable chitosan of different sizes were used to encapsulate antitumor drug tamoxifen (Tam) and its metabolites 4-hydroxytamoxifen (4-Hydroxytam) and endoxifen (Endox). The interactions of tamoxifen and its metabolites with chitosan 15, 100 and 200 KD were investigated in aqueous solution, using FTIR, fluorescence spectroscopic methods and molecular modeling. The structural analysis showed that tamoxifen and its metabolites bind chitosan via both hydrophilic and hydrophobic contacts with overall binding constants of Ktam-ch-15 = 8.7 (±0.5)×103 M−1, Ktam-ch-100 = 5.9 (±0.4)×105 M−1, Ktam-ch-200 = 2.4 (±0.4)×105 M−1 and Khydroxytam-ch-15 = 2.6(±0.3)×104 M−1, Khydroxytam – ch-100 = 5.2 (±0.7)×106 M−1 and Khydroxytam-ch-200 = 5.1 (±0.5)×105 M−1, Kendox-ch-15 = 4.1 (±0.4)×103 M−1, Kendox-ch-100 = 1.2 (±0.3)×106 M−1 and Kendox-ch-200 = 4.7 (±0.5)×105 M−1 with the number of drug molecules bound per chitosan (n) 2.8 to 0.5. The order of binding is ch-100>200>15 KD with stronger complexes formed with 4-hydroxytamoxifen than tamoxifen and endoxifen. The molecular modeling showed the participation of polymer charged NH2 residues with drug OH and NH2 groups in the drug-polymer adducts. The free binding energies of −3.46 kcal/mol for tamoxifen, −3.54 kcal/mol for 4-hydroxytamoxifen and −3.47 kcal/mol for endoxifen were estimated for these drug-polymer complexes. The results show chitosan 100 KD is stronger carrier for drug delivery than chitosan-15 and chitosan-200 KD.
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Affiliation(s)
- Daniel Agudelo
- Departement of Chemistry-Biology, University of Québec at Trois-Rivières, Trois-Rivières, Québec, Canada
| | - Sriwanna Sanyakamdhorn
- Departement of Chemistry-Biology, University of Québec at Trois-Rivières, Trois-Rivières, Québec, Canada
| | - Shoherh Nafisi
- Department of Chemistry, San Jose State University, San Jose, California, United States of America
- * E-mail: (H-AT-R); (SN)
| | - Heidar-Ali Tajmir-Riahi
- Departement of Chemistry-Biology, University of Québec at Trois-Rivières, Trois-Rivières, Québec, Canada
- * E-mail: (H-AT-R); (SN)
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Sensitive HPLC–PDA determination of tamoxifen and its metabolites N-desmethyltamoxifen, 4-hydroxytamoxifen and endoxifen in human plasma. J Pharm Biomed Anal 2013; 76:13-20. [DOI: 10.1016/j.jpba.2012.12.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 12/05/2012] [Accepted: 12/05/2012] [Indexed: 11/21/2022]
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Huber-Wechselberger AE, Niedetzky P, Aigner I, Haschke-Becher E. Impact of CYP2D6 polymorphism on tamoxifen therapy: where are we? Wien Med Wochenschr 2012; 162:252-61. [PMID: 22688624 DOI: 10.1007/s10354-012-0118-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 03/20/2012] [Indexed: 01/06/2023]
Abstract
Tamoxifen is a mainstay in the treatment of hormone-receptor sensitive breast cancer. To be effective, it needs conversion into 4-hydroxy-tamoxifen and endoxifen. The key enzyme involved is encoded by the gene CYP2D6 of which several, sometimes population-specific alleles are known. Corresponding enzyme variants may result in poor, intermediate, and extensive metabolization and therefore different steady-state plasma levels of active metabolites. Those are hypothesized to be linked to clinical outcomes of tamoxifen therapy. However, a wealth of mostly retrospective cohort studies came up with conflicting results. Appraisal of these studies is difficult and a metaanalysis impossible due to heterogeneity of patient populations, disease factors, treatment modalities, and measured outcomes. As standardization would not overcome intrinsic limitations of retrospective analyses, prospective trials comparing genotype-guided versus unsighted tamoxifen treatment are required to prove whether routine CYP2D6 genotyping is clinically effective and cost-effective.
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Affiliation(s)
- Ariana E Huber-Wechselberger
- Competence Center of Molecular Biology and Genetics, Elisabethinen Hospital Linz GmbH, Fadingerstrasse 1, 4020, Linz, Austria.
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Dickschen K, Willmann S, Thelen K, Lippert J, Hempel G, Eissing T. Physiologically Based Pharmacokinetic Modeling of Tamoxifen and its Metabolites in Women of Different CYP2D6 Phenotypes Provides New Insight into the Tamoxifen Mass Balance. Front Pharmacol 2012; 3:92. [PMID: 22661948 PMCID: PMC3357105 DOI: 10.3389/fphar.2012.00092] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Accepted: 04/27/2012] [Indexed: 12/15/2022] Open
Abstract
Tamoxifen is a first-line endocrine agent in the mechanism-based treatment of estrogen receptor positive (ER+) mammary carcinoma and applied to breast cancer patients all over the world. Endoxifen is a secondary and highly active metabolite of tamoxifen that is formed among others by the polymorphic cytochrome P450 2D6 (CYP2D6). It is widely accepted that CYP2D6 poor metabolizers exert a pronounced decrease in endoxifen steady-state plasma concentrations compared to CYP2D6 extensive metabolizers. Nevertheless, an in-depth understanding of the chain of cause and effect between CYP2D6 genotype, endoxifen steady-state plasma concentration, and subsequent tamoxifen treatment benefit still remains to be evolved. In this study, physiologically based pharmacokinetic (PBPK)-modeling was applied to mechanistically investigate the impact of CYP2D6 phenotype on endoxifen formation in female breast cancer patients undergoing tamoxifen therapy. A PBPK-model of tamoxifen and its pharmacologically important metabolites N-desmethyltamoxifen (NDM-TAM), 4-hydroxytamoxifen (4-OH-TAM), and endoxifen was developed and validated. This model is able to simulate the pharmacokinetics (PK) after single and repeated oral tamoxifen doses in female breast cancer patients in dependence of the CYP2D6 phenotype. A detailed model-based analysis of the mass balance offered support for a recent hypothesis stating a more prominent role for endoxifen formation from 4-OH-TAM. In the future this model provides a good basis to further investigate the linkage of PK, mode of action, and treatment outcome in dependence of factors such as phenotype, ethnicity, or co-treatment with CYP2D6 inhibitors.
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Affiliation(s)
- Kristin Dickschen
- Klinische Pharmazie, Institut für Pharmazeutische und Medizinische Chemie, Westfälische Wilhelms-Universität Münster Münster, Germany
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19
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Liquid chromatography-mass spectrometry method for the quantification of tamoxifen and its metabolite 4-hydroxytamoxifen in rat plasma: application to interaction study with biochanin A (an isoflavone). J Chromatogr B Analyt Technol Biomed Life Sci 2011; 879:2845-51. [PMID: 21890435 DOI: 10.1016/j.jchromb.2011.07.036] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 07/26/2011] [Accepted: 07/27/2011] [Indexed: 11/20/2022]
Abstract
Tamoxifen is the agent of choice for the treatment of estrogen receptor-positive breast cancer. Tamoxifen is a substrate of P-glycoprotein (P-gp) and microsomal cytochrome P450 (CYP) 3A, and biochanin A (BCA) is an inhibitor of P-gp and CYP3A. Hence, it could be expected that BCA would affect the pharmacokinetics of tamoxifen. In the present study we have developed and validated a simple, sensitive and specific LC-ESI-MS/MS method for the simultaneous quantification of tamoxifen and its metabolite 4-hydroxytamoxifen with 100 μL rat plasma using centchroman as an internal standard (IS). Tamoxifen, 4-hydroxytamoxifen and IS were separated on a Supelco Discovery C18 (4.6 mm × 50 mm, 5.0 μm) column under isocratic condition using 0.0 1M ammonium acetate (pH 4.5):acetonitrile (10:90, v/v) as a mobile phase. The mobile phase was delivered at a flow rate of 0.8 mL/min. The method was proved to be accurate and precise at linearity range of 0.78-200 ng/mL with a correlation coefficient (r) of ≥ 0.996. The intra- and inter-day assay precision ranged from 1.89 to 8.54% and 3.97 to 10.26%, respectively; and intra- and inter-day assay accuracy was between 87.63 and 109.06% and 96 and 103.89%, respectively for both the analytes. The method was successfully applied to study the effect of oral co-administration of BCA (an isoflavone) on the pharmacokinetics of tamoxifen and 4-hydroxytamoxifen in female rats. The coadministration of BCA caused no significant changes in the pharmacokinetics of tamoxifen and 4-hydroxytamoxifen. However, the peak plasma concentration (C(max)) of 4-hydroxytamoxifen in BCA pretreated rats was significantly (P<0.05) lower than those from control group.
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Bourassa P, Dubeau S, Maharvi GM, Fauq AH, Thomas TJ, Tajmir-Riahi HA. Locating the binding sites of anticancer tamoxifen and its metabolites 4-hydroxytamoxifen and endoxifen on bovine serum albumin. Eur J Med Chem 2011; 46:4344-53. [PMID: 21777996 DOI: 10.1016/j.ejmech.2011.07.005] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Revised: 06/21/2011] [Accepted: 07/02/2011] [Indexed: 10/18/2022]
Abstract
The breast anticancer drug tamoxifen and its metabolites bind serum albumins. We located the binding sites of tamoxifen, 4-hydroxytamoxifen and endoxifen on bovine serum albumin (BSA). FTIR, CD and fluorescence spectroscopic methods as well as molecular modeling were used to characterize the drug binding mode, binding constant and the effect of drug binding on BSA stability and conformation. Structural analysis showed that tamoxifen and its metabolites bind BSA via hydrophobic and hydrophilic interactions with overall binding constants of K(tam-BSA) = 1.96 (± 0.2)× 10(4)M(-1), K(4-hydroxytam-BSA) = 1.80 (± 0.4)× 10(4)M(-1) and K(endox-BSA) = 8.01 (± 0.8)× 10(3)M(-1). The number of bound drug molecules per protein is 1.7 (tamoxifen), 1.4 (4-hydroxitamoxifen) and 1.13 (endoxifen). The participation of several amino acid residues in drug-protein complexes is stabilized by extended hydrogen bonding network with the free binding energy of -13.47 (tamoxifen), -13.79 (4-hydroxtamoxifen) and -12.72 kcal/mol (endoxifen). The order of binding is 4-hydroxy-tamoxen>tamoxifen>endoxifen. BSA conformation was altered by a major reduction of α-helix from 63% (free BSA) to 41% with tamoxifen, to 39% with 4-hydroxytamoxifen, and to 47% with endoxifen. In addition, an increase in turn and random coil structures was found, suggesting partial protein unfolding. These results suggest that serum albumins might act as carrier proteins for tamoxifen and its metabolites in delivering them to target tissues.
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Affiliation(s)
- P Bourassa
- Département de Chimie-Biologie, Université du Québec à Trois-Rivières, CP 500, Trois-Rivières, Québec G9A 5H7, Canada
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Binding of antitumor tamoxifen and its metabolites 4-hydroxytamoxifen and endoxifen to human serum albumin. Biochimie 2011; 93:1089-101. [DOI: 10.1016/j.biochi.2011.03.006] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Accepted: 03/12/2011] [Indexed: 11/17/2022]
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22
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Iusuf D, Teunissen SF, Wagenaar E, Rosing H, Beijnen JH, Schinkel AH. P-Glycoprotein (ABCB1) Transports the Primary Active Tamoxifen Metabolites Endoxifen and 4-Hydroxytamoxifen and Restricts Their Brain Penetration. J Pharmacol Exp Ther 2011; 337:710-7. [DOI: 10.1124/jpet.110.178301] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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An ultra performance liquid chromatography–tandem MS assay for tamoxifen metabolites profiling in plasma: First evidence of 4′-hydroxylated metabolites in breast cancer patients. J Chromatogr B Analyt Technol Biomed Life Sci 2010; 878:3402-14. [DOI: 10.1016/j.jchromb.2010.10.027] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 10/26/2010] [Accepted: 10/26/2010] [Indexed: 11/23/2022]
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Teunissen S, Rosing H, Schinkel A, Schellens J, Beijnen J. Bioanalytical methods for determination of tamoxifen and its phase I metabolites: A review. Anal Chim Acta 2010; 683:21-37. [DOI: 10.1016/j.aca.2010.10.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Revised: 10/06/2010] [Accepted: 10/08/2010] [Indexed: 10/18/2022]
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Tamoxifen decreases ovarian follicular loss from experimental toxicant DMBA and chemotherapy agents cyclophosphamide and doxorubicin in the rat. J Assist Reprod Genet 2010; 27:591-7. [PMID: 20711751 DOI: 10.1007/s10815-010-9463-y] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Accepted: 07/23/2010] [Indexed: 10/19/2022] Open
Abstract
INTRODUCTION we serendipitously observed a protective effect of tamoxifen against depletion of ovarian follicles by 7,12-dimethylbenzanthracene (DMBA), a chemical carcinogen, during a cancer prevention study. Such ovarian protection is being sought as an alternative approach to fertility preservation in human cancer patients. METHODS rats received tamoxifen (0, 1 mg or 2.5 mg/kg/d) and DMBA (0, 1, 2 mg/kg/wk) or cyclophosphamide (0, 35, 50 mg/kg/wk). Ovarian follicles were quantified and effects on fertility and litter size were tested. Cultured oocytes were exposed to chemotherapy drug doxorubicin, with or without 4-hydroxytamoxifen (4HT). RESULTS DMBA and cyclophosphamide decreased the number of primordial and total follicles, and this reduction was prevented by tamoxifen. Cyclophosphamide tended to reduce fertility and lessened neonatal survival. Tamoxifen reversed these defects. Doxorubicin caused oocyte fragmentation which was prevented by 4HT. CONCLUSIONS tamoxifen decreases follicle loss and improves reproductive function following exposure to ovarian toxicants including chemotherapy drugs in the female rat.
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Abstract
Tamoxifen is the most widely used anti-oestrogen for the treatment of hormone-dependent breast cancer. The pharmacological activity of tamoxifen is dependent on its conversion by the hepatic drug-metabolizing enzyme cytochrome P450 2D6 (CYP2D6) to its abundant metabolite, endoxifen. Patients with reduced CYP2D6 activity, as a result of either their genotype or induction by the co-administration of drugs that inhibit CYP2D6 function, produce little endoxifen and seem to derive inferior therapeutic benefit from tamoxifen. Here we review the existing data that relate CYP2D6 genotypes to response to tamoxifen and discuss whether the analysis of the CYP2D6 genotype might be an early example of a pharmacogenetic tool for optimizing breast cancer therapy.
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Affiliation(s)
- Janelle M Hoskins
- UNC Institute for Pharmacogenomics and Individualized Therapy, Division of Pharmacotherapy and Experimental Therapeutics, University of North Carolina, Chapel Hill, 27599, North Carolina, USA
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Zolk O, Solbach TF, König J, Fromm MF. Structural determinants of inhibitor interaction with the human organic cation transporter OCT2 (SLC22A2). Naunyn Schmiedebergs Arch Pharmacol 2008; 379:337-48. [PMID: 19002438 DOI: 10.1007/s00210-008-0369-5] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2008] [Accepted: 10/17/2008] [Indexed: 12/21/2022]
Abstract
The organic cation transporter 2 (OCT2) provides an important pathway for the uptake of cationic compounds in the kidney, which is the essential step in their elimination from the organism. Although many drugs have been identified which interact with human OCT2, structural elements required for an interaction with OCT2 are not well defined. To address this issue, HEK293 cells stably expressing human OCT2 were generated. IC(50) values of commonly used drugs for inhibition of [(3)H]MPP(+) uptake were determined and correlated with physicochemical descriptors. We found only a significant correlation between the topological polar surface area (TPSA) and IC(50) values (r = 0.71, p < 0.0001). Structural alignment of most potent inhibitor drugs of OCT2-mediated MPP(+) uptake was used to construct a two-point pharmacophore consisting of an ion-pair interaction site and a hydrophobic aromatic site separated by 5.0 A. Taken together, our data identify structural determinants for inhibitor interactions with OCT2.
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Affiliation(s)
- Oliver Zolk
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Erlangen-Nuremberg, Fahrstr. 17, 91054, Erlangen, Germany.
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