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Teslenko I, Watson CJW, Chen G, Lazarus P. Inhibition of the aromatase enzyme by exemestane cysteine conjugates. Mol Pharmacol 2022; 102:MOLPHARM-AR-2022-000545. [PMID: 35953090 PMCID: PMC9595203 DOI: 10.1124/molpharm.122.000545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 08/02/2022] [Accepted: 08/05/2022] [Indexed: 11/25/2022] Open
Abstract
Exemestane (EXE) is an aromatase inhibitor used to treat hormone-dependent breast cancer. EXE is extensively metabolized, with unchanged EXE and its active metabolite 17-dihydroexemestane (17-DHE) accounting for 17 and 12%, respectively, of total plasma EXE in vivo The major circulating EXE metabolites are the cysteine conjugates of EXE and 17-DHE, and the 17-DHE glucuronide, which together account for 70% of total plasma EXE in vivo The goal of the present study was to examine the inhibition potential of major metabolites of EXE through inhibition assays using aromatase-overexpressing cells and pooled ovarian tissues. Estrone formation was used as a measure of aromatase activity and was detected and quantified using UPLC-MS. EXE-cys, 17β-DHE, and 17β-DHE-cys all exhibited inhibition of estrone formation at both 1 µM and 10 µM concentrations, with 17β-DHE and EXE-cys showing significant inhibition of estrone formation (63% each) at 10 µM. In contrast, 17β-DHE-Gluc displayed minimal inhibition (5-8%) at both concentrations. In ovarian tissue, EXE-cys and 17β-DHE showed similar patterns of inhibition, with 49% and 47% inhibition, respectively, at 10 µM. The IC50 value for EXE-cys (16 {plus minus} 10 µM) was similar to 17β-DHE (9.2 {plus minus} 2.7 µM) and higher than EXE (1.3 {plus minus} 0.28 µM), and all three compounds showed time-dependent inhibition with IC50 shifts of 13 {plus minus} 10, 5.0 {plus minus} 2.5 and 36 {plus minus} 12-fold, respectively. Given its high circulating levels in patients taking EXE, these results suggest that EXE-cys may contribute to the pharmacologic effect of EXE in vivo Significance Statement The current study is the first to examine the major phase II metabolites of EXE (EXE-cys, 17β-DHE-cys, and 17β-DHE-Gluc) for inhibition potential against the target enzyme, aromatase (CYP19A1). EXE-cys was found to significantly inhibit aromatase in a time dependent manner. Given its high circulating levels in patients taking EXE, this phase II metabolite may play an important role in reducing circulating estrogen levels in vivo.
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Affiliation(s)
- Irina Teslenko
- Pharmaceutical Sciences, Washington State University, United States
| | | | - Gang Chen
- Pharmaceutical Sciences, WSU College of Pharmacy, United States
| | - Philip Lazarus
- Pharmaceutical Sciences, Washington State University College of Pharmacy, United States
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Miranda C, Galleguillos M, Torres R, Tardón K, Cáceres DD, Lee K, Redal MA, Varela NM, Quiñones LA. Preliminary Pharmacogenomic-Based Predictive Models of Tamoxifen Response in Hormone-dependent Chilean Breast Cancer Patients. Front Pharmacol 2021; 12:661443. [PMID: 34899282 PMCID: PMC8656167 DOI: 10.3389/fphar.2021.661443] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 10/25/2021] [Indexed: 12/15/2022] Open
Abstract
Tamoxifen (TAM), a selective oestrogen receptor modulator, is one of the most used treatments in oestrogen receptor-positive (ER+) early and metastatic breast cancer (BC) patients. The response to TAM has a high degree of inter-individual variability. This is mainly due to genetic variants in CYP2D6 gene, as well as other genes encoding proteins involved in the TAM pharmacokinetic and/or pharmacodynamic. Therefore, prediction of the TAM response using these genetic factors together with other non-genetic variables may be relevant to improve breast cancer treatment. Thus, in this work, we used genetic polymorphisms and clinical variables for TAM response modelling. One hundred sixty-two ER + BC patients with 2 years of TAM treatment were retrospectively recruited, and the genetic polymorphisms CYP2D6*4, CYP3A4*1B (CYP3A4*1.001), CYP3A5*3, UGT2B7*2, UGT2B15*2, SULT1A1*2, and ESRA V364E were analyzed by PCR-RFLP. Concomitantly, the therapeutic response was obtained from clinical records for association with genotypes using univariate and multivariate biostatistical models. Our results show that UGT2B15*1/*2 genotype protects against relapse (OR = 0.09; p = 0.02), CYP3A5*3/*3 genotype avoids endometrial hyperplasia (OR = 0.07; p = 0.01), SULT1A1*1/*2 genotype avoids vaginal bleeding (OR = 0.09; p = 0.03) and ESRA 364E/364E genotype increases the probability of vaginal bleeding (OR = 5.68; p = 0.02). Logistic regression models, including genomic and non-genomic variables, allowed us to obtain preliminary predictive models to explain relapse (p = 0.010), endometrial hyperplasia (p = 0.002) and vaginal bleeding (p = 0.014). Our results suggest that the response to TAM treatment in ER + BC patients might be associated with the presence of the studied genetic variants in UGT2B15, CYP3A5, SULT1A1 and ESRA genes. After clinical validation protocols, these models might be used to help to predict a percentage of BC relapse and adverse reactions, improving the individual response to TAM-based treatment.
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Affiliation(s)
- Carla Miranda
- Laboratory of Chemical Carcinogenesis and Pharmacogenetics, Department of Basic-Clinical Oncology (DOBC), Faculty of Medicine, University of Chile, Santiago, Chile
| | - Macarena Galleguillos
- Laboratory of Chemical Carcinogenesis and Pharmacogenetics, Department of Basic-Clinical Oncology (DOBC), Faculty of Medicine, University of Chile, Santiago, Chile
| | | | | | - Dante D Cáceres
- Institute of Population Health, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Kuen Lee
- Laboratory of Chemical Carcinogenesis and Pharmacogenetics, Department of Basic-Clinical Oncology (DOBC), Faculty of Medicine, University of Chile, Santiago, Chile.,Faculty of Medicine, University of Chile, Santiago, Chile
| | - María A Redal
- Genetic Division, Department of Medicine, Hospital de Clínicas José de San Martín, Buenos Aires, Argentina.,Latin American Network for Implementation and Validation of Clinical Pharmacogenomics Guidelines (RELIVAF-CYTED), Madrid, Spain
| | - Nelson M Varela
- Laboratory of Chemical Carcinogenesis and Pharmacogenetics, Department of Basic-Clinical Oncology (DOBC), Faculty of Medicine, University of Chile, Santiago, Chile.,Latin American Network for Implementation and Validation of Clinical Pharmacogenomics Guidelines (RELIVAF-CYTED), Madrid, Spain
| | - Luis A Quiñones
- Laboratory of Chemical Carcinogenesis and Pharmacogenetics, Department of Basic-Clinical Oncology (DOBC), Faculty of Medicine, University of Chile, Santiago, Chile.,Latin American Network for Implementation and Validation of Clinical Pharmacogenomics Guidelines (RELIVAF-CYTED), Madrid, Spain
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Teslenko I, Watson CJW, Xia Z, Chen G, Lazarus P. Characterization of Cytosolic Glutathione S-Transferases Involved in the Metabolism of the Aromatase Inhibitor, Exemestane. Drug Metab Dispos 2021; 49:1047-1055. [PMID: 34593616 PMCID: PMC11025106 DOI: 10.1124/dmd.121.000635] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 09/28/2021] [Indexed: 12/14/2022] Open
Abstract
Exemestane (EXE) is a hormonal therapy used to treat estrogen receptor-positive breast cancer by inhibiting the final step of estrogen biosynthesis catalyzed by the enzyme aromatase. Cysteine conjugates of EXE and its active metabolite 17β-dihydro-EXE (DHE) are the major metabolites found in both the urine and plasma of patients taking EXE. The initial step in cysteine conjugate formation is glutathione conjugation catalyzed by the glutathione S-transferase (GST) family of enzymes. The goal of the present study was to identify cytosolic hepatic GSTs active in the GST-mediated metabolism of EXE and 17β-DHE. Twelve recombinant cytosolic hepatic GSTs were screened for their activity against EXE and 17β-DHE, and glutathionylated EXE and 17β-DHE conjugates were detected by ultra-performance liquid chromatography tandem mass spectrometry. GST α (GSTA) isoform 1, GST μ (GSTM) isoform 3 and isoform 1 were active against EXE, whereas only GSTA1 exhibited activity against 17β-DHE. GSTM1 exhibited the highest affinity against EXE with a Michaelis-Menten constant (KM) value that was 3.8- and 7.1-fold lower than that observed for GSTA1 and GSTM3, respectively. Of the three GSTs, GSTM3 exhibited the highest intrinsic clearance against EXE (intrinsic clearance = 0.14 nl·min-1·mg-1). The KM values observed for human liver cytosol against EXE (46 μM) and 17β-DHE (77 μM) were similar to those observed for recombinant GSTA1 (53 and 30 μM, respectively). Western blot analysis revealed that GSTA1 and GSTM1 composed 4.3% and 0.57%, respectively, of total protein in human liver cytosol; GSTM3 was not detected. These data suggest that GSTA1 is the major hepatic cytosolic enzyme involved in the clearance of EXE and its major active metabolite, 17β-DHE. SIGNIFICANCE STATEMENT: Most previous studies related to the metabolism of the aromatase inhibitor exemestane (EXE) have focused mainly on phase I metabolic pathways and the glucuronidation phase II metabolic pathway. However, recent studies have indicated that glutathionylation is the major metabolic pathway for EXE. The present study is the first to characterize hepatic glutathione S-transferase (GST) activity against EXE and 17β-dihydro-EXE and to identify GST α 1 and GST μ 1 as the major cytosolic GSTs involved in the hepatic metabolism of EXE.
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Affiliation(s)
- Irina Teslenko
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Christy J W Watson
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Zuping Xia
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Gang Chen
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
| | - Philip Lazarus
- Department of Pharmaceutical Sciences, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington
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Goda AE, Elsisi AE, Sokkar SS, Abdelrazik NM. Enhanced in vivo targeting of estrogen receptor alpha signaling in murine mammary adenocarcinoma by nilotinib/rosuvastatin novel combination. Toxicol Appl Pharmacol 2020; 404:115185. [PMID: 32771489 DOI: 10.1016/j.taap.2020.115185] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 07/19/2020] [Accepted: 08/04/2020] [Indexed: 02/06/2023]
Abstract
The development of resistance to endocrine therapy of estrogen receptor alpha (ERα)-positive breast cancer is inevitable, necessitating the introduction of alternative treatment strategies. Therefore, the current study was carried out to investigate the in vivo efficacy and tolerability of nilotinib/rosuvastatin novel combination against ERα-positive breast carcinoma. Results showed that treatment of tumor-bearing mice with nilotinib/rosuvastatin exerted a significant antitumor activity. Mechanistically, the combination treatment efficiently inhibited the in vivo ERα protein expression, whereas ERα mRNA levels were unaffected suggesting a posttranslational regulation. In addition, the combination treatment markedly downregulated the expression of two ERα downstream target genes: C3 and pS2 confirming the inhibition of ERα signaling in vivo. Further, nilotinib/rosuvastatin combination strongly induced apoptosis evidenced by a marked caspase-3 cleavage and downregulation of tumor nitric oxide levels. Moreover, histopathology showed significant declines in mitotic figures and tumor giant cells implying the in vivo capability of the combination treatment to interfere with cancer cell proliferation and persistence. Of note, the combination treatment abrogated nilotinib-induced hypercholesterolemia and did not adversely affect the liver function or body weight. Overall, the present study provided evidences that warrant further assessment of nilotinib/rosuvastatin combination as an alternative therapeutic modality for ERα-positive breast cancer.
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Affiliation(s)
- Ahmed E Goda
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Tanta University, Tanta 31527, Egypt.
| | - Alaa E Elsisi
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Tanta University, Tanta 31527, Egypt
| | - Samia S Sokkar
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Tanta University, Tanta 31527, Egypt
| | - Noha M Abdelrazik
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Tanta University, Tanta 31527, Egypt
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