1
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Rendic SP, Guengerich FP. Formation of potentially toxic metabolites of drugs in reactions catalyzed by human drug-metabolizing enzymes. Arch Toxicol 2024; 98:1581-1628. [PMID: 38520539 DOI: 10.1007/s00204-024-03710-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 02/20/2024] [Indexed: 03/25/2024]
Abstract
Data are presented on the formation of potentially toxic metabolites of drugs that are substrates of human drug metabolizing enzymes. The tabular data lists the formation of potentially toxic/reactive products. The data were obtained from in vitro experiments and showed that the oxidative reactions predominate (with 96% of the total potential toxication reactions). Reductive reactions (e.g., reduction of nitro to amino group and reductive dehalogenation) participate to the extent of 4%. Of the enzymes, cytochrome P450 (P450, CYP) enzymes catalyzed 72% of the reactions, myeloperoxidase (MPO) 7%, flavin-containing monooxygenase (FMO) 3%, aldehyde oxidase (AOX) 4%, sulfotransferase (SULT) 5%, and a group of minor participating enzymes to the extent of 9%. Within the P450 Superfamily, P450 Subfamily 3A (P450 3A4 and 3A5) participates to the extent of 27% and the Subfamily 2C (P450 2C9 and P450 2C19) to the extent of 16%, together catalyzing 43% of the reactions, followed by P450 Subfamily 1A (P450 1A1 and P450 1A2) with 15%. The P450 2D6 enzyme participated in an extent of 8%, P450 2E1 in 10%, and P450 2B6 in 6% of the reactions. All other enzymes participate to the extent of 14%. The data show that, of the human enzymes analyzed, P450 enzymes were dominant in catalyzing potential toxication reactions of drugs and their metabolites, with the major role assigned to the P450 Subfamily 3A and significant participation of the P450 Subfamilies 2C and 1A, plus the 2D6, 2E1 and 2B6 enzymes contributing. Selected examples of drugs that are activated or proposed to form toxic species are discussed.
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Affiliation(s)
| | - F Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, 37232-0146, USA
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2
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Vavrová K, Indra R, Pompach P, Heger Z, Hodek P. The impact of individual human cytochrome P450 enzymes on oxidative metabolism of anticancer drug lenvatinib. Biomed Pharmacother 2021; 145:112391. [PMID: 34847475 DOI: 10.1016/j.biopha.2021.112391] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 10/20/2021] [Accepted: 11/02/2021] [Indexed: 11/26/2022] Open
Abstract
Lenvatinib, a small molecule tyrosine kinase inhibitor (TKI), exhibits good inhibitory effect in several types of carcinomas. Specifically, it is the most effective TKI used for treatment of thyroid cancer. To extend pharmacokinetics data on this anticancer agent, we aimed to identify the metabolites of lenvatinib formed during in vitro incubation of lenvatinib with human hepatic microsomes or recombinant cytochromes P450 (CYPs) by using high performance liquid chromatography and mass spectrometry. The role of CYPs in the oxidation of lenvatinib was initially investigated in hepatic microsomes using specific CYP inhibitors. CYP-catalytic activities in each microsomal sample were correlated with the amounts of lenvatinib metabolites formed by these samples. Further, human recombinant CYPs were employed in the metabolic studies. Based on our data, lenvatinib is metabolized to O-desmethyl lenvatinib, N-descyclopropyl lenvatinib and lenvatinib N-oxide. In the presence of cytochrome b5, recombinant CYP3A4 was the most efficient to form these metabolites. In addition, CYP1A1 significantly contributes to the lenvatinib metabolism. It was even more efficient in forming of O-desmethyl lenvatinib than CYP3A4 in the absence of cytochrome b5. The present study indicates that further research focused on drug-drug interactions, in particular on CYP3A4 and CYP1A1 modulators, is needed. This will pave new avenues towards TKIs-mediated personalized therapy.
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Affiliation(s)
- Katarína Vavrová
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 6, 128 00 Prague 2, Czech Republic
| | - Radek Indra
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 6, 128 00 Prague 2, Czech Republic.
| | - Petr Pompach
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 6, 128 00 Prague 2, Czech Republic
| | - Zbyněk Heger
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, 613 00 Brno, Czech Republic; Central European Institute of Technology, Brno University of Technology, Purkynova 656/123, 612 00 Brno, Czech Republic
| | - Petr Hodek
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 6, 128 00 Prague 2, Czech Republic
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3
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Kim D, Kim V, Tateishi Y, Guengerich FP. Cytochrome b 5 Binds Tightly to Several Human Cytochrome P450 Enzymes. Drug Metab Dispos 2021; 49:902-909. [PMID: 34330716 DOI: 10.1124/dmd.121.000475] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 07/13/2021] [Indexed: 01/18/2023] Open
Abstract
Numerous studies have been reported in the past 50-plus years regarding the stimulatory role of cytochrome b 5 (b 5) in some, but not all, microsomal cytochrome P450 (P450) reactions with drugs and steroids. A missing element in most of these studies has been a sensitive and accurate measure of binding affinities of b 5 with P450s. In the course of work with P450 17A1, we developed a fluorescent derivative of a human b 5 site-directed mutant, Alexa 488-T70C-b 5, that could be used in binding assays at sub-μM concentrations. Alexa 488-T70C-b 5 bound to human P450s 1A2, 2B6, 2C8, 2C9, 2E1, 2S1, 4A11, 3A4, and 17A1, with estimated K d values ranging from 2.5 to 61 nM. Only weak binding was detected with P450 2D6, and no fluorescence attenuation was observed with P450 2A6. All of the P450s that bound b 5 have some reported activity stimulation except for P450 2S1. The affinity of P450 3A4 for b 5 was decreased somewhat by the presence of a substrate or inhibitor. The fluorescence of a P450 3A4•Alexa 488-T70C-b 5 complex was partially restored by titration with NADPH-P450 reductase (POR) (K d,apparent 89 nM), suggesting the existence of a ternary P450 3A4-b 5-POR complex, as observed previously with P450 17A1. Gel filtration evidence was also obtained for this ternary complex with P450 3A4. Overall, the results indicated that the affinity of b 5 for many P450s is very high, and that ternary P450-b 5-POR complexes are relevant in P450 3A4 reactions as opposed to a shuttle mechanism. SIGNIFICANCE STATEMENT: High-affinity binding of cytochrome b 5 (b 5) (K d < 100 nM) was observed with many drug-metabolizing cytochrome P450 (P450) enzymes. There is some correlation of binding with reported stimulation, with several exceptions. Evidence is provided for a ternary P450 3A4-b 5-NADPH-P450 reductase complex.
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Affiliation(s)
- Donghak Kim
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146 (D.K., Y.T., F.P.G.), and Department of Biological Sciences, Konkuk University, Seoul, Republic of Korea (D.K., V.K.)
| | - Vitchan Kim
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146 (D.K., Y.T., F.P.G.), and Department of Biological Sciences, Konkuk University, Seoul, Republic of Korea (D.K., V.K.)
| | - Yasuhiro Tateishi
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146 (D.K., Y.T., F.P.G.), and Department of Biological Sciences, Konkuk University, Seoul, Republic of Korea (D.K., V.K.)
| | - F Peter Guengerich
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146 (D.K., Y.T., F.P.G.), and Department of Biological Sciences, Konkuk University, Seoul, Republic of Korea (D.K., V.K.)
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4
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Abstract
The regulation of brain cytochrome P450 enzymes (CYPs) is different compared with respective hepatic enzymes. This may result from anatomical bases and physiological functions of the two organs. The brain is composed of a variety of functional structures built of different interconnected cell types endowed with specific receptors that receive various neuronal signals from other brain regions. Those signals activate transcription factors or alter functioning of enzyme proteins. Moreover, the blood-brain barrier (BBB) does not allow free penetration of all substances from the periphery into the brain. Differences in neurotransmitter signaling, availability to endogenous and exogenous active substances, and levels of transcription factors between neuronal and hepatic cells lead to differentiated expression and susceptibility to the regulation of CYP genes in the brain and liver. Herein, we briefly describe the CYP enzymes of CYP1-3 families, their distribution in the brain, and discuss brain-specific regulation of CYP genes. In parallel, a comparison to liver CYP regulation is presented. CYP enzymes play an essential role in maintaining the levels of bioactive molecules within normal ranges. These enzymes modulate the metabolism of endogenous neurochemicals, such as neurosteroids, dopamine, serotonin, melatonin, anandamide, and exogenous substances, including psychotropics, drugs of abuse, neurotoxins, and carcinogens. The role of these enzymes is not restricted to xenobiotic-induced neurotoxicity, but they are also involved in brain physiology. Therefore, it is crucial to recognize the function and regulation of CYP enzymes in the brain to build a foundation for future medicine and neuroprotection and for personalized treatment of brain diseases.
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Affiliation(s)
- Wojciech Kuban
- Department of Pharmacokinetics and Drug Metabolism, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
| | - Władysława Anna Daniel
- Department of Pharmacokinetics and Drug Metabolism, Maj Institute of Pharmacology, Polish Academy of Sciences, Kraków, Poland
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Indra R, Vavrová K, Pompach P, Heger Z, Hodek P. Identification of Enzymes Oxidizing the Tyrosine Kinase Inhibitor Cabozantinib: Cabozantinib Is Predominantly Oxidized by CYP3A4 and Its Oxidation Is Stimulated by cyt b 5 Activity. Biomedicines 2020; 8:biomedicines8120547. [PMID: 33260548 PMCID: PMC7759869 DOI: 10.3390/biomedicines8120547] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 11/13/2020] [Accepted: 11/26/2020] [Indexed: 12/24/2022] Open
Abstract
Herein, the in vitro metabolism of tyrosine kinase inhibitor cabozantinib, the drug used for the treatment of metastatic medullary thyroid cancer and advanced renal cell carcinoma, was studied using hepatic microsomal samples of different human donors, human recombinant cytochromes P450 (CYPs), flavin-containing mono-oxygenases (FMOs) and aldehyde oxidase. After incubation with human microsomes, three metabolites, namely cabozantinib N-oxide, desmethyl cabozantinib and monohydroxy cabozantinib, were detected. Significant correlations were found between CYP3A4 activity and generation of all metabolites. The privileged role of CYP3A4 was further confirmed by examining the effect of CYP inhibitors and by human recombinant enzymes. Only four of all tested human recombinant cytochrome P450 were able to oxidize cabozantinib, and CYP3A4 exhibited the most efficient activity. Importantly, cytochrome b5 (cyt b5) stimulates the CYP3A4-catalyzed formation of cabozantinib metabolites. In addition, cyt b5 also stimulates the activity of CYP3A5, whereas two other enzymes, CYP1A1 and 1B1, were not affected by cyt b5. Since CYP3A4 exhibits high expression in the human liver and was found to be the most efficient enzyme in cabozantinib oxidation, we examined the kinetics of this oxidation. The present study provides substantial insights into the metabolism of cabozantinib and brings novel findings related to cabozantinib pharmacokinetics towards possible utilization in personalized medicine.
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Affiliation(s)
- Radek Indra
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 6, 12800 Prague 2, Czech Republic; (K.V.); (P.P.); (P.H.)
- Correspondence: ; Tel.: +420-221-951-285
| | - Katarína Vavrová
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 6, 12800 Prague 2, Czech Republic; (K.V.); (P.P.); (P.H.)
| | - Petr Pompach
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 6, 12800 Prague 2, Czech Republic; (K.V.); (P.P.); (P.H.)
| | - Zbyněk Heger
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, 61300 Brno, Czech Republic;
- Central European Institute of Technology, Brno University of Technology, Purkynova 656/123, 61200 Brno, Czech Republic
| | - Petr Hodek
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 6, 12800 Prague 2, Czech Republic; (K.V.); (P.P.); (P.H.)
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Indra R, Pompach P, Vavrová K, Jáklová K, Heger Z, Adam V, Eckschlager T, Kopečková K, Arlt VM, Stiborová M. Cytochrome P450 and flavin-containing monooxygenase enzymes are responsible for differential oxidation of the anti-thyroid-cancer drug vandetanib by human and rat hepatic microsomal systems. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2020; 74:103310. [PMID: 31837525 DOI: 10.1016/j.etap.2019.103310] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 11/24/2019] [Accepted: 12/02/2019] [Indexed: 06/10/2023]
Abstract
We studied the in vitro metabolism of the anti-thyroid-cancer drug vandetanib in a rat animal model and demonstrated that N-desmethylvandetanib and vandetanib N-oxide are formed by NADPH- or NADH-mediated reactions catalyzed by rat hepatic microsomes and pure biotransformation enzymes. In addition to the structural characterization of vandetanib metabolites, individual rat enzymes [cytochrome P450 (CYP) and flavin-containing monooxygenase (FMO)] capable of oxidizing vandetanib were identified. Generation of N-desmethylvandetanib, but not that of vandetanib N-oxide, was attenuated by CYP3A and 2C inhibitors while inhibition of FMO decreased formation of vandetanib N-oxide. These results indicate that liver microsomal CYP2C/3A and FMO1 are major enzymes participating in the formation of N-desmethylvandetanib and vandetanib N-oxide, respectively. Rat recombinant CYP2C11 > >3A1 > 3A2 > 1A1 > 1A2 > 2D1 > 2D2 were effective in catalyzing the formation of N-desmethylvandetanib. Results of the present study explain differences between the CYP- and FMO-catalyzed vandetanib oxidation in rat and human liver reported previously and the enzymatic mechanisms underlying this phenomenon.
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Affiliation(s)
- Radek Indra
- Department of Biochemistry, Faculty of Science, Charles University, Albertov, 2030, 128 40 Prague 2, Czech Republic
| | - Petr Pompach
- Department of Biochemistry, Faculty of Science, Charles University, Albertov, 2030, 128 40 Prague 2, Czech Republic
| | - Katarína Vavrová
- Department of Biochemistry, Faculty of Science, Charles University, Albertov, 2030, 128 40 Prague 2, Czech Republic
| | - Kateřina Jáklová
- Department of Biochemistry, Faculty of Science, Charles University, Albertov, 2030, 128 40 Prague 2, Czech Republic
| | - Zbyněk Heger
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, 61300 Brno, Czech Republic
| | - Vojtěch Adam
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, 61300 Brno, Czech Republic
| | - Tomáš Eckschlager
- Department of Pediatric Hematology and Oncology, 2nd Medical Faculty, Charles University and University Hospital Motol, 150 06 Prague, Czech Republic
| | - Kateřina Kopečková
- Department of Oncology, 2nd Faculty of Medicine, Charles University and University Hospital Motol, 150 06 Prague 5, Czech Republic
| | - Volker Manfred Arlt
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, 150 Stamford Street, London SE1 9NH, United Kingdom
| | - Marie Stiborová
- Department of Biochemistry, Faculty of Science, Charles University, Albertov, 2030, 128 40 Prague 2, Czech Republic.
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7
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Lin J, Tang M, Zhao R, Du Q, Shen L, Du G, Zhang Y, Li Y, Pan X. Synthetic Optimization of Ellipticine and Antitumor Activity of Novel Hexacyclic Derivatives of Ellipticine. Curr Pharm Des 2019; 25:3578-3589. [DOI: 10.2174/1381612825666190404122650] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 03/27/2019] [Indexed: 01/05/2023]
Abstract
Background:
For decades, a great deal of research work has been done to synthesize ellipticine and
its derivatives because of their potential antitumor properties and anti-HIV activities. However, the resonance
structures in different media, a low level of solubility at physiological pH and systemic toxicity have prevented
the use of ellipticine as a therapeutic agent. Besides, the low yield and complex steps of ellipticine synthesis limit
its application.
Methods:
A high-yield synthetic procedure of ellipticine has been optimized, and the total yield was up to 50%
without silica gel column chromatography. Novel hexacyclic ellipticine derivatives were synthesized by coupling
ellipticine with o-aminobenzoic acid. Their cytotoxicities against HCT116, MGC803, HT29 and MCF-7 tumor
cells were evaluated.
Results:
The synthesis process of ellipticine was optimized, and the total yield of the synthetic route was increased
to 50% through several operation steps optimization. Fourteen ellipticine hexacyclic derivatives were
synthesized. The synthetic compounds were screened for anti-tumor activity in vivo and in vitro, and some of the
derivatives had good anti-tumor activity.
Conclusion:
Compared with ellipticine, the compound 1l showed higher antitumor activity and better tolerance to
tumor models. The compound 1l treatment increased the percentage of late apoptotic cells from 3.1% (DMSO) to
21.6% (20.0 μM) in NCI-H460 cells. It also was observed the effect of 1l on G2 phase arrest was similar as that
of ellipticine. The mechanism of action indicated compound 1l could be a topoisomerase IIα poison. These studies
provided the basis for the pharmacodynamics and toxicology of ellipticine, and further clarifies the structureactivity
relationship of antitumor activity of ellipticine.
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Affiliation(s)
- Jingjing Lin
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines and Beijing Key Laboratory of Active Substances Discovery and Druggability Evaluation, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Mei Tang
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines and Beijing Key Laboratory of Active Substances Discovery and Druggability Evaluation, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Ru Zhao
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines and Beijing Key Laboratory of Active Substances Discovery and Druggability Evaluation, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Qianqian Du
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines and Beijing Key Laboratory of Active Substances Discovery and Druggability Evaluation, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Longying Shen
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines and Beijing Key Laboratory of Active Substances Discovery and Druggability Evaluation, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Guohua Du
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines and Beijing Key Laboratory of Active Substances Discovery and Druggability Evaluation, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Yafen Zhang
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines and Beijing Key Laboratory of Active Substances Discovery and Druggability Evaluation, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Yan Li
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines and Beijing Key Laboratory of Active Substances Discovery and Druggability Evaluation, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Xiandao Pan
- State Key Laboratory of Bioactive Substance and Function of Natural Medicines and Beijing Key Laboratory of Active Substances Discovery and Druggability Evaluation, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
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8
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Indra R, Pompach P, Martínek V, Takácsová P, Vavrová K, Heger Z, Adam V, Eckschlager T, Kopečková K, Arlt VM, Stiborová M. Identification of Human Enzymes Oxidizing the Anti-Thyroid-Cancer Drug Vandetanib and Explanation of the High Efficiency of Cytochrome P450 3A4 in its Oxidation. Int J Mol Sci 2019; 20:ijms20143392. [PMID: 31295928 PMCID: PMC6679423 DOI: 10.3390/ijms20143392] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 07/07/2019] [Accepted: 07/08/2019] [Indexed: 12/15/2022] Open
Abstract
The metabolism of vandetanib, a tyrosine kinase inhibitor used for treatment of symptomatic/progressive medullary thyroid cancer, was studied using human hepatic microsomes, recombinant cytochromes P450 (CYPs) and flavin-containing monooxygenases (FMOs). The role of CYPs and FMOs in the microsomal metabolism of vandetanib to N-desmethylvandetanib and vandetanib-N-oxide was investigated by examining the effects of CYP/FMO inhibitors and by correlating CYP-/FMO-catalytic activities in each microsomal sample with the amounts of N-desmethylvandetanib/vandetanib-N-oxide formed by these samples. CYP3A4/FMO-activities significantly correlated with the formation of N-desmethylvandetanib/ vandetanib-N-oxide. Based on these studies, most of the vandetanib metabolism was attributed to N-desmethylvandetanib/vandetanib-N-oxide to CYP3A4/FMO3. Recombinant CYP3A4 was most efficient to form N-desmethylvandetanib, while FMO1/FMO3 generated N-oxide. Cytochrome b5 stimulated the CYP3A4-catalyzed formation of N-desmethylvandetanib, which is of great importance because CYP3A4 is not only most efficient in generating N-desmethylvandetanib, but also most significant due to its high expression in human liver. Molecular modeling indicated that binding of more than one molecule of vandetanib into the CYP3A4-active center can be responsible for the high efficiency of CYP3A4 N-demethylating vandetanib. Indeed, the CYP3A4-mediated reaction exhibits kinetics of positive cooperativity and this corresponded to the in silico model, where two vandetanib molecules were found in CYP3A4-active center.
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Affiliation(s)
- Radek Indra
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, CZ-12843 Prague 2, Czech Republic
| | - Petr Pompach
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, CZ-12843 Prague 2, Czech Republic
| | - Václav Martínek
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, CZ-12843 Prague 2, Czech Republic
| | - Paulína Takácsová
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, CZ-12843 Prague 2, Czech Republic
| | - Katarína Vavrová
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, CZ-12843 Prague 2, Czech Republic
| | - Zbyněk Heger
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, CZ-61300 Brno, Czech Republic
| | - Vojtěch Adam
- Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, CZ-61300 Brno, Czech Republic
| | - Tomáš Eckschlager
- Department of Pediatric Hematology and Oncology, 2nd Faculty of Medicine, Charles University and University Hospital Motol, V Uvalu 84/1, CZ-150 06 Prague 5, Czech Republic
| | - Kateřina Kopečková
- Department of Oncology, 2nd Medical Faculty, Charles University and University Hospital Motol, V Uvalu 84/1, CZ-150 06 Prague 5, Czech Republic
| | - Volker Manfred Arlt
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, 150 Stamford Street, London SE1 9NH, UK
- NIHR Health Protection Research Unit in Health Impact of Environmental Hazards at King's College London in partnership with Public Health England and Imperial College London, 150 Stamford Street, London SE1 9NH, UK
| | - Marie Stiborová
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, CZ-12843 Prague 2, Czech Republic.
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Ellipticine-loaded apoferritin nanocarrier retains DNA adduct-based cytochrome P450-facilitated toxicity in neuroblastoma cells. Toxicology 2019; 419:40-54. [DOI: 10.1016/j.tox.2019.03.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 03/20/2019] [Accepted: 03/22/2019] [Indexed: 12/17/2022]
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10
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Reed L, Indra R, Mrizova I, Moserova M, Schmeiser HH, Wolf CR, Henderson CJ, Stiborova M, Phillips DH, Arlt VM. Application of hepatic cytochrome b 5/P450 reductase null (HBRN) mice to study the role of cytochrome b 5 in the cytochrome P450-mediated bioactivation of the anticancer drug ellipticine. Toxicol Appl Pharmacol 2019; 366:64-74. [PMID: 30685480 PMCID: PMC6382462 DOI: 10.1016/j.taap.2019.01.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2018] [Revised: 01/14/2019] [Accepted: 01/22/2019] [Indexed: 01/30/2023]
Abstract
The anticancer drug ellipticine exerts its genotoxic effects after metabolic activation by cytochrome P450 (CYP) enzymes. The present study has examined the role of cytochrome P450 oxidoreductase (POR) and cytochrome b5 (Cyb5), electron donors to P450 enzymes, in the CYP-mediated metabolism and disposition of ellipticine in vivo. We used Hepatic Reductase Null (HRN) and Hepatic Cytochrome b5/P450 Reductase Null (HBRN) mice. HRN mice have POR deleted specifically in hepatocytes; HBRN mice also have Cyb5 deleted in the liver. Mice were treated once with 10 mg/kg body weight ellipticine (n = 4/group) for 24 h. Ellipticine-DNA adduct levels measured by 32P-postlabelling were significantly lower in HRN and HBRN livers than in wild-type (WT) livers; however no significant difference was observed between HRN and HBRN livers. Ellipticine-DNA adduct formation in WT, HRN and HBRN livers correlated with Cyp1a and Cyp3a enzyme activities measured in hepatic microsomes in the presence of NADPH confirming the importance of P450 enzymes in the bioactivation of ellipticine in vivo. Hepatic microsomal fractions were also utilised in incubations with ellipticine and DNA in the presence of NADPH, cofactor for POR, and NADH, cofactor for Cyb5 reductase (Cyb5R), to examine ellipticine-DNA adduct formation. With NADPH adduct formation decreased as electron donors were lost which correlated with the formation of the reactive metabolites 12- and 13-hydroxy-ellipticine in hepatic microsomes. No difference in adduct formation was observed in the presence of NADH. Our study demonstrates that Cyb5 contributes to the P450-mediated bioactivation of ellipticine in vitro, but not in vivo.
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Affiliation(s)
- Lindsay Reed
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, London, United Kingdom
| | - Radek Indra
- Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - Iveta Mrizova
- Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - Michaela Moserova
- Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - Heinz H Schmeiser
- Division of Radiopharmaceutical Chemistry, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - C Roland Wolf
- Division of Cancer Research, Jacqui Wood Cancer Centre, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, United Kingdom
| | - Colin J Henderson
- Division of Cancer Research, Jacqui Wood Cancer Centre, School of Medicine, University of Dundee, Ninewells Hospital, Dundee, United Kingdom
| | - Marie Stiborova
- Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic
| | - David H Phillips
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, London, United Kingdom
| | - Volker M Arlt
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, London, United Kingdom.
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11
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Willis AJ, Indra R, Wohak LE, Sozeri O, Feser K, Mrizova I, Phillips DH, Stiborova M, Arlt VM. The impact of chemotherapeutic drugs on the CYP1A1-catalysed metabolism of the environmental carcinogen benzo[a]pyrene: Effects in human colorectal HCT116 TP53(+/+), TP53(+/-) and TP53(-/-) cells. Toxicology 2018; 398-399:1-12. [PMID: 29471073 PMCID: PMC6593262 DOI: 10.1016/j.tox.2018.02.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 01/29/2018] [Accepted: 02/16/2018] [Indexed: 02/02/2023]
Abstract
Polycyclic aromatic hydrocarbons such as benzo[a]pyrene (BaP) can induce cytochrome P450 1A1 (CYP1A1) via a p53-dependent mechanism. The effect of different p53-activating chemotherapeutic drugs on CYP1A1 expression, and the resultant effect on BaP metabolism, was investigated in a panel of isogenic human colorectal HCT116 cells with differing TP53 status. Cells that were TP53(+/+), TP53(+/-) or TP53(-/-) were treated for up to 48 h with 60 μM cisplatin, 50 μM etoposide or 5 μM ellipticine, each of which caused high p53 induction at moderate cytotoxicity (60-80% cell viability). We found that etoposide and ellipticine induced CYP1A1 in TP53(+/+) cells but not in TP53(-/-) cells, demonstrating that the mechanism of CYP1A1 induction is p53-dependent; cisplatin had no such effect. Co-incubation experiments with the drugs and 2.5 μM BaP showed that: (i) etoposide increased CYP1A1 expression in TP53(+/+) cells, and to a lesser extent in TP53(-/-) cells, compared to cells treated with BaP alone; (ii) ellipticine decreased CYP1A1 expression in TP53(+/+) cells in BaP co-incubations; and (iii) cisplatin did not affect BaP-mediated CYP1A1 expression. Further, whereas cisplatin and etoposide had virtually no influence on CYP1A1-catalysed BaP metabolism, ellipticine treatment strongly inhibited BaP bioactivation. Our results indicate that the underlying mechanisms whereby etoposide and ellipticine regulate CYP1A1 expression must be different and may not be linked to p53 activation alone. These results could be relevant for smokers, who are exposed to increased levels of BaP, when prescribing chemotherapeutic drugs. Beside gene-environment interactions, more considerations should be given to potential drug-environment interactions during chemotherapy.
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Affiliation(s)
- Alexandra J Willis
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, 150 Stamford Street, London SE1 9NH, United Kingdom
| | - Radek Indra
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Laura E Wohak
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, 150 Stamford Street, London SE1 9NH, United Kingdom
| | - Osman Sozeri
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, 150 Stamford Street, London SE1 9NH, United Kingdom
| | - Kerstin Feser
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, 150 Stamford Street, London SE1 9NH, United Kingdom
| | - Iveta Mrizova
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - David H Phillips
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, 150 Stamford Street, London SE1 9NH, United Kingdom; NIHR Health Protection Research Unit in Health Impact of Environmental Hazards at King's College London in partnership with Public Health England, London, 150 Stamford Street, London SE1 9NH, United Kingdom
| | - Marie Stiborova
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Volker M Arlt
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, 150 Stamford Street, London SE1 9NH, United Kingdom; NIHR Health Protection Research Unit in Health Impact of Environmental Hazards at King's College London in partnership with Public Health England, London, 150 Stamford Street, London SE1 9NH, United Kingdom.
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12
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Stiborova M. Formation of Covalent DNA Adducts by Enzymatically Activated Carcinogens and Drugs In Vitro and Their Determination by 32P-postlabeling. J Vis Exp 2018. [PMID: 29630053 DOI: 10.3791/57177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Covalent DNA adducts formed by chemicals or drugs with carcinogenic potency are judged as one of the most important factors in the initiation phase of carcinogenic processes. This covalent binding, which is considered the cause of tumorigenesis, is now evaluated as a central dogma of chemical carcinogenesis. Here, methods are described employing the reactions catalyzed by cytochrome P450 and additional biotransformation enzymes to investigate the potency of chemicals or drugs for their activation to metabolites forming these DNA adducts. Procedures are presented describing the isolation of cellular fractions possessing biotransformation enzymes (microsomal and cytosolic samples with cytochromes P450 or other biotransformation enzymes, i.e., peroxidases, NADPH:cytochrome P450 oxidoreductase, NAD(P)H:quinone oxidoreductase, or xanthine oxidase). Furthermore, methods are described that can be used for the metabolic activation of analyzed chemicals by these enzymes as well as those for isolation of DNA. Further, the appropriate methods capable of detecting and quantifying chemical/drug-derived DNA adducts, i.e., different modifications of the 32P-postlabeling technique and employment of radioactive-labeled analyzed chemicals, are shown in detail.
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13
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Jeřábek P, Florián J, Martínek V. Lipid molecules can induce an opening of membrane-facing tunnels in cytochrome P450 1A2. Phys Chem Chem Phys 2018; 18:30344-30356. [PMID: 27722524 DOI: 10.1039/c6cp03692a] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cytochrome P450 1A2 (P450 1A2, CYP1A2) is a membrane-bound enzyme that oxidizes a broad range of hydrophobic substrates. The structure and dynamics of both the catalytic and trans-membrane (TM) domains of this enzyme in the membrane/water environment were investigated using a multiscale computational approach, including coarse-grained and all-atom molecular dynamics. Starting from the spontaneous self-assembly of the system containing the TM or soluble domain immersed in randomized dilauroyl phosphatidylcholine (DLPC)/water mixture into their respective membrane-bound forms, we reconstituted the membrane-bound structure of the full-length P450 1A2. This structure includes a TM helix that spans the membrane, while being connected to the catalytic domain by a short flexible loop. Furthermore, in this model, the upper part of the TM helix interacts directly with a conserved and highly hydrophobic N-terminal proline-rich segment of the catalytic domain; this segment and the FG loop are immersed in the membrane, whereas the remaining portion of the catalytic domain remains exposed to aqueous solution. The shallow membrane immersion of the catalytic domain induces a depression in the opposite intact layer of the phospholipids. This structural effect may help in stabilizing the position of the TM helix directly beneath the catalytic domain. The partial immersion of the catalytic domain also allows for the enzyme substrates to enter the active site from either aqueous solution or phospholipid environment via several solvent- and membrane-facing tunnels in the full-length P450 1A2. The calculated tunnel dynamics indicated that the opening probability of the membrane-facing tunnels is significantly enhanced when a DLPC molecule spontaneously penetrates into the membrane-facing tunnel 2d. The energetics of the lipid penetration process were assessed by the linear interaction energy (LIE) approximation, and found to be thermodynamically feasible.
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Affiliation(s)
- Petr Jeřábek
- Department of Biochemistry, Charles University, Faculty of Science, Albertov 2030, 128 43 Prague 2, Czech Republic
| | - Jan Florián
- Department of Chemistry and Biochemistry, Loyola University Chicago, 1032 W. Sheridan Rd., Chicago, IL 60660, USA
| | - Václav Martínek
- Department of Biochemistry, Charles University, Faculty of Science, Albertov 2030, 128 43 Prague 2, Czech Republic and Department of Teaching and Didactics of Chemistry, Charles University, Faculty of Science, Albertov 3, 128 43 Prague 2, Czech Republic.
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14
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The Histone Deacetylase Inhibitor Valproic Acid Exerts a Synergistic Cytotoxicity with the DNA-Damaging Drug Ellipticine in Neuroblastoma Cells. Int J Mol Sci 2018; 19:ijms19010164. [PMID: 29304031 PMCID: PMC5796113 DOI: 10.3390/ijms19010164] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Revised: 12/22/2017] [Accepted: 12/28/2017] [Indexed: 02/03/2023] Open
Abstract
Neuroblastoma (NBL) originates from undifferentiated cells of the sympathetic nervous system. Chemotherapy is judged to be suitable for successful treatment of this disease. Here, the influence of histone deacetylase (HDAC) inhibitor valproate (VPA) combined with DNA-damaging chemotherapeutic, ellipticine, on UKF-NB-4 and SH-SY5Y neuroblastoma cells was investigated. Treatment of these cells with ellipticine in combination with VPA led to the synergism of their anticancer efficacy. The effect is more pronounced in the UKF-NB-4 cell line, the line with N-myc amplification, than in SH-SY5Y cells. This was associated with caspase-3-dependent induction of apoptosis in UKF-NB-4 cells. The increase in cytotoxicity of ellipticine in UKF-NB-4 by VPA is dictated by the sequence of drug administration; the increased cytotoxicity was seen only after either simultaneous exposure to these drugs or after pretreatment of cells with ellipticine before their treatment with VPA. The synergism of treatment of cells with VPA and ellipticine seems to be connected with increased acetylation of histones H3 and H4. Further, co-treatment of cells with ellipticine and VPA increased the formation of ellipticine-derived DNA adducts, which indicates an easier accessibility of ellipticine to DNA in cells by its co-treatment with VPA and also resulted in higher ellipticine cytotoxicity. The results are promising for in vivo studies and perhaps later for clinical studies of combined treatment of children suffering from high-risk NBL.
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15
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Stiborová M, Indra R, Moserová M, Bořek-Dohalská L, Hodek P, Frei E, Kopka K, Schmeiser HH, Arlt VM. Comparison of human cytochrome P450 1A1-catalysed oxidation of benzo[ a]pyrene in prokaryotic and eukaryotic expression systems. MONATSHEFTE FUR CHEMIE 2017; 148:1959-1969. [PMID: 29104317 PMCID: PMC5653725 DOI: 10.1007/s00706-017-2002-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 05/14/2017] [Indexed: 11/16/2022]
Abstract
ABSTRACT Cytochrome P450 (CYP) 1A1 is the most important enzyme activating and detoxifying the human carcinogen benzo[a]pyrene (BaP). In the previous studies, we had shown that not only the canonic NADPH:CYP oxidoreductase (POR) can act as electron donor but also cytochrome b5 and its reductase, NADH:cytochrome b5 reductase. Here, we studied the role of the expression system used on the metabolites generated and the levels of DNA adducts formed by activated BaP. We used an eukaryotic and a prokaryotic cellular system (Supersomes, microsomes isolated from insect cells, and Bactosomes, a membrane fraction of Escherichia coli, each transfected with cDNA of human CYP1A1 and POR). These were reconstituted with cytochrome b5 with and without NADH:cytochrome b5 reductase. We evaluated the effectiveness of each cofactor, NADPH and NADH, to mediate BaP metabolism. We found that both systems differ in catalysing the reactions activating and detoxifying BaP. Two BaP-derived DNA adducts were generated by the CYP1A1-Supersomes, both in the presence of NADPH and NADH, whereas NADPH but not NADH was able to support this reaction in the CYP1A1-Bactosomes. Seven BaP metabolites were found in Supersomes with NADPH or NADH, whereas NADPH but not NADH was able to generate five BaP metabolites in Bactosomes. Our study demonstrates different catalytic efficiencies of CYP1A1 expressed in prokaryotic and eukaryotic cells in BaP bioactivation indicating some limitations in the use of E. coli cells for such studies. GRAPHICAL ABSTRACT
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Affiliation(s)
- Marie Stiborová
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Radek Indra
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Michaela Moserová
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Lucie Bořek-Dohalská
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Petr Hodek
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Eva Frei
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Klaus Kopka
- Division of Radiopharmaceutical Chemistry, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Heinz H. Schmeiser
- Division of Radiopharmaceutical Chemistry, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Volker M. Arlt
- Analytical and Environmental Sciences Division, MRC-PHE Centre for Environment and Health, King’s College London, London, SE1 9NH UK
- NIHR Health Protection Research Unit in Health Impact of Environmental Hazards at King’s College London in Partnership with Public Health England, London, SE1 9NH UK
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16
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Stiborová M, Indra R, Frei E, Kopečková K, Schmeiser HH, Eckschlager T, Adam V, Heger Z, Arlt VM, Martínek V. Cytochrome b5 plays a dual role in the reaction cycle of cytochrome P450 3A4 during oxidation of the anticancer drug ellipticine. MONATSHEFTE FUR CHEMIE 2017; 148:1983-1991. [PMID: 29104319 PMCID: PMC5653753 DOI: 10.1007/s00706-017-1986-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 04/13/2017] [Indexed: 12/18/2022]
Abstract
Abstract Ellipticine is an anticancer agent that forms covalent DNA adducts after enzymatic activation by cytochrome P450 (CYP) enzymes, mainly by CYP3A4. This process is one of the most important ellipticine DNA-damaging mechanisms for its antitumor action. Here, we investigated the efficiencies of human hepatic microsomes and human recombinant CYP3A4 expressed with its reductase, NADPH:CYP oxidoreductase (POR), NADH:cytochrome b5 reductase and/or cytochrome b5 in Supersomes™ to oxidize this drug. We also evaluated the effectiveness of coenzymes of two of the microsomal reductases, NADPH as a coenzyme of POR, and NADH as a coenzyme of NADH:cytochrome b5 reductase, to mediate ellipticine oxidation in these enzyme systems. Using HPLC analysis we detected up to five ellipticine metabolites, which were formed by human hepatic microsomes and human CYP3A4 in the presence of NADPH or NADH. Among ellipticine metabolites, 9-hydroxy-, 12-hydroxy-, and 13-hydroxyellipticine were formed by hepatic microsomes as the major metabolites, while 7-hydroxyellipticine and the ellipticine N2-oxide were the minor ones. Human CYP3A4 in Supersomes™ generated only three metabolic products, 9-hydroxy-, 12-hydroxy-, and 13-hydroxyellipticine. Using the 32P-postlabeling method two ellipticine-derived DNA adducts were generated by microsomes and the CYP3A4-Supersome system, both in the presence of NADPH and NADH. These adducts were derived from the reaction of 13-hydroxy- and 12-hydroxyellipticine with deoxyguanosine in DNA. In the presence of NADPH or NADH, cytochrome b5 stimulated the CYP3A4-mediated oxidation of ellipticine, but the stimulation effect differed for individual ellipticine metabolites. This heme protein also stimulated the formation of both ellipticine-DNA adducts. The results demonstrate that cytochrome b5 plays a dual role in the CYP3A4-catalyzed oxidation of ellipticine: (1) cytochrome b5 mediates CYP3A4 catalytic activities by donating the first and second electron to this enzyme in its catalytic cycle, indicating that NADH:cytochrome b5 reductase can substitute NADPH-dependent POR in this enzymatic reaction and (2) cytochrome b5 can act as an allosteric modifier of the CYP3A4 oxygenase. Graphical abstract ![]()
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Affiliation(s)
- Marie Stiborová
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Radek Indra
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Eva Frei
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Kateřina Kopečková
- Department of Oncology, 2nd Faculty of Medicine, Charles University and University Hospital Motol, V Uvalu 84, 150 06 Prague 5, Czech Republic
| | - Heinz H Schmeiser
- Division of Radiopharmaceutical Chemistry, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Tomáš Eckschlager
- Department of Pediatric Hematology and Oncology, 2nd Medical Faculty, Charles University and University Hospital Motol, V Uvalu 84, 150 06 Prague 5, Czech Republic
| | - Vojtěch Adam
- Laboratory of Metallomics and Nanotechnology, Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, 61300 Brno, Czech Republic
| | - Zbyněk Heger
- Laboratory of Metallomics and Nanotechnology, Department of Chemistry and Biochemistry, Mendel University in Brno, Zemedelska 1, 61300 Brno, Czech Republic
| | - Volker M Arlt
- Analytical and Environmental Sciences Division, MRC-PHE Centre for Environment and Health, King's College London, London, SE1 9NH UK
| | - Václav Martínek
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
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17
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Stiborová M, Indra R, Moserová M, Frei E, Schmeiser HH, Kopka K, Philips DH, Arlt V. NADH:Cytochrome b5 Reductase and Cytochrome b5 Can Act as Sole Electron Donors to Human Cytochrome P450 1A1-Mediated Oxidation and DNA Adduct Formation by Benzo[a]pyrene. Chem Res Toxicol 2016; 29:1325-34. [PMID: 27404282 PMCID: PMC4987862 DOI: 10.1021/acs.chemrestox.6b00143] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Indexed: 11/29/2022]
Abstract
Benzo[a]pyrene (BaP) is a human carcinogen that covalently binds to DNA after activation by cytochrome P450 (P450). Here, we investigated whether NADH:cytochrome b5 reductase (CBR) in the presence of cytochrome b5 can act as sole electron donor to human P450 1A1 during BaP oxidation and replace the canonical NADPH:cytochrome P450 reductase (POR) system. We also studied the efficiencies of the coenzymes of these reductases, NADPH as a coenzyme of POR, and NADH as a coenzyme of CBR, to mediate BaP oxidation. Two systems containing human P450 1A1 were utilized: human recombinant P450 1A1 expressed with POR, CBR, epoxide hydrolase, and cytochrome b5 in Supersomes and human recombinant P450 1A1 reconstituted with POR and/or with CBR and cytochrome b5 in liposomes. BaP-9,10-dihydrodiol, BaP-7,8-dihydrodiol, BaP-1,6-dione, BaP-3,6-dione, BaP-9-ol, BaP-3-ol, a metabolite of unknown structure, and two BaP-DNA adducts were generated by the P450 1A1-Supersomes system, both in the presence of NADPH and in the presence of NADH. The major BaP-DNA adduct detected by (32)P-postlabeling was characterized as 10-(deoxyguanosin-N(2)-yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydro-BaP (assigned adduct 1), while the minor adduct is probably a guanine adduct derived from 9-hydroxy-BaP-4,5-epoxide (assigned adduct 2). BaP-3-ol as the major metabolite, BaP-9-ol, BaP-1,6-dione, BaP-3,6-dione, an unknown metabolite, and adduct 2 were observed in the system using P450 1A1 reconstituted with POR plus NADPH. When P450 1A1 was reconstituted with CBR and cytochrome b5 plus NADH, BaP-3-ol was the predominant metabolite too, and an adduct 2 was also generated. Our results demonstrate that the NADH/cytochrome b5/CBR system can act as the sole electron donor both for the first and second reduction of P450 1A1 during the oxidation of BaP in vitro. They suggest that NADH-dependent CBR can replace NADPH-dependent POR in the P450 1A1-catalyzed metabolism of BaP.
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Affiliation(s)
- Marie Stiborová
- Department
of Biochemistry, Faculty of Science, Charles
University, Albertov
2030, 128 40, Prague 2, Czech
Republic
| | - Radek Indra
- Department
of Biochemistry, Faculty of Science, Charles
University, Albertov
2030, 128 40, Prague 2, Czech
Republic
| | - Michaela Moserová
- Department
of Biochemistry, Faculty of Science, Charles
University, Albertov
2030, 128 40, Prague 2, Czech
Republic
| | - Eva Frei
- Department
of Biochemistry, Faculty of Science, Charles
University, Albertov
2030, 128 40, Prague 2, Czech
Republic
| | - Heinz H. Schmeiser
- Division
of Radiopharmaceutical Chemistry, German
Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Klaus Kopka
- Department
of Biochemistry, Faculty of Science, Charles
University, Albertov
2030, 128 40, Prague 2, Czech
Republic
| | - David H. Philips
- Analytical
and Environmental Sciences Division, MRC-PHE Centre for Environment
and Health, King’s College London, Franklin-Wilkins Building, 150 Stamford
Street, London SE1 9NH, United Kingdom
- NIHR
Health Protection Research Unit in Health Impact of Environmental
Hazards at King’s College London in Partnership with Public
Health England, Franklin-Wilkins
Building, 150 Stamford Street, London SE1 9NH, United Kingdom
| | - Volker
M. Arlt
- Analytical
and Environmental Sciences Division, MRC-PHE Centre for Environment
and Health, King’s College London, Franklin-Wilkins Building, 150 Stamford
Street, London SE1 9NH, United Kingdom
- NIHR
Health Protection Research Unit in Health Impact of Environmental
Hazards at King’s College London in Partnership with Public
Health England, Franklin-Wilkins
Building, 150 Stamford Street, London SE1 9NH, United Kingdom
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18
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Šulc M, Indra R, Moserová M, Schmeiser HH, Frei E, Arlt VM, Stiborová M. The impact of individual cytochrome P450 enzymes on oxidative metabolism of benzo[a]pyrene in human livers. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2016; 57:229-35. [PMID: 26919089 PMCID: PMC4855618 DOI: 10.1002/em.22001] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 01/13/2016] [Accepted: 01/14/2016] [Indexed: 05/09/2023]
Abstract
Benzo[a]pyrene (BaP) is a human carcinogen that covalently binds to DNA after metabolic activation by cytochrome P450 (CYP) enzymes. In this study human recombinant CYPs (CYP1A1, 1A2, 1B1, 2A6, 2B6, 2C8, 2C9, 2C19, 2E1, 3A4, and 3A5) were expressed in Supersomes™ together with their reductases, NADPH:CYP oxidoreductase, epoxide hydrolase and cytochrome b5 , to investigate BaP metabolism. Human CYPs produced up to eight BaP metabolites. Among these, BaP-7,8-dihydrodiol and BaP-9-ol, which are intermediates in BaP-derived DNA adduct formation, were mainly formed by CYP1A1 and 1B1, and to a lesser extent by CYP2C19 and 3A4. BaP-3-ol, a metabolite that is a 'detoxified' product of BaP, was formed by most human CYPs tested, although CYP1A1 and 1B1 produced it the most efficiently. Based on the amounts of the individual BaP metabolites formed by these CYPs and their expression levels in human liver, we determined their contributions to BaP metabolite formation in this organ. Our results indicate that hepatic CYP1A1 and CYP2C19 are most important in the activation of BaP to BaP-7,8-dihydrodiol, whereas CYP2C19, 3A4, and 1A1 are the major enzymes contributing to the formation of BaP-9-ol. BaP-3-ol is predominantly formed by hepatic CYP3A4, while CYP1A1 and 2C19 are less active.
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Affiliation(s)
- Miroslav Šulc
- Department of BiochemistryFaculty of Science, Charles UniversityPragueCzech Republic
| | - Radek Indra
- Department of BiochemistryFaculty of Science, Charles UniversityPragueCzech Republic
| | - Michaela Moserová
- Department of BiochemistryFaculty of Science, Charles UniversityPragueCzech Republic
| | - Heinz H. Schmeiser
- Division of Radiopharmaceutical ChemistryGerman Cancer Research Center (DKFZ)HeidelbergGermany
| | - Eva Frei
- Department of BiochemistryFaculty of Science, Charles UniversityPragueCzech Republic
| | - Volker M. Arlt
- Analytical and Environmental Sciences DivisionMRC‐PHE Centre for Environment and Health, King's College LondonLondonUnited Kingdom
- NIHR Health Protection Research Unit in Health Impact of Environmental Hazards at King's College London in Partnership with Public Health EnglandLondonUnited Kingdom
| | - Marie Stiborová
- Department of BiochemistryFaculty of Science, Charles UniversityPragueCzech Republic
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19
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Mrízová I, Moserová M, Milichovský J, Šulc M, Kizek R, Kubáčková K, Arlt VM, Stiborová M. Heterologous expression of human cytochrome P450 2S1 in Escherichia coli and investigation of its role in metabolism of benzo[ a]pyrene and ellipticine. MONATSHEFTE FUR CHEMIE 2016; 147:881-888. [PMID: 27110039 PMCID: PMC4828499 DOI: 10.1007/s00706-016-1738-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 01/21/2016] [Indexed: 12/30/2022]
Abstract
ABSTRACT Cytochrome P450 (CYP) 2S1 is "orphan" CYP that is overexpressed in several epithelial tissues and many human tumors. The pure enzyme is required for better understanding of its biological functions. Therefore, human CYP2S1 was considered to be prepared by the gene manipulations and heterologous expression in Escherichia coli. Here, the conditions suitable for efficient expression of human CYP2S1 protein from plasmid pCW containing the human CYP2S1 gene were optimized and the enzyme purified to homogeneity. The identity of CYP2S1 as the product of heterologous expression was confirmed by dodecyl sulfate-polyacrylamide gel electrophoresis, Western blotting, and mass spectrometry. To confirm the presence of the enzymatically active CYP2S1, the CO spectrum of purified CYP2S1 was recorded. Since CYP2S1 was shown to catalyze oxidation of compounds having polycyclic aromatic structures, the prepared enzyme has been tested to metabolize the compounds having this structural character; namely, the human carcinogen benzo[a]pyrene (BaP), its 7,8-dihydrodiol derivative, and an anticancer drug ellipticine. Reaction mixtures contained besides the test compounds the CYP2S1 enzyme reconstituted with NADPH:CYP reductase (POR) in liposomes, and/or this CYP in the presence of cumene hydroperoxide or hydrogen peroxide. High performance liquid chromatography was employed for separation of BaP, BaP-7,8-dihydrodiol, and ellipticine metabolites. The results found in this study demonstrate that CYP2S1 in the presence of cumene hydroperoxide or hydrogen peroxide catalyzes oxidation of two of the test xenobiotics, a metabolite of BaP, BaP-7,8-dihydrodiol, and ellipticine. Whereas BaP-7,8,9,10-tetrahydrotetrol was formed as a product of BaP-7,8-dihydrodiol oxidation, ellipticine was oxidized to 12-hydroxyellipticine, 13-hydroxyellipticine, and the ellipticine N2-oxide. GRAPHICAL ABSTRACT
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Affiliation(s)
- Iveta Mrízová
- />Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Michaela Moserová
- />Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Jan Milichovský
- />Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Miroslav Šulc
- />Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - René Kizek
- />Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University in Brno, 613 00 Brno, Czech Republic
| | - Kateřina Kubáčková
- />Department of Oncology, 2nd Faculty of Medicine, Charles University and University Hospital Motol, V Uvalu 84, 150 06 Prague 5, Czech Republic
| | - Volker M. Arlt
- />Analytical and Environmental Sciences Division, MRC-PHE Centre for Environment and Health, King’s College London, London, SE1 9NH UK
| | - Marie Stiborová
- />Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
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Jeřábek P, Florián J, Martínek V. Membrane-Anchored Cytochrome P450 1A2–Cytochrome b5 Complex Features an X-Shaped Contact between Antiparallel Transmembrane Helices. Chem Res Toxicol 2016; 29:626-36. [DOI: 10.1021/acs.chemrestox.5b00349] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Petr Jeřábek
- Department
of Biochemistry, Faculty of Science, Charles University in Prague, Albertov 2030, 128 43 Prague 2, Czech Republic
| | - Jan Florián
- Department
of Chemistry and Biochemistry, Loyola University Chicago, 1032 West Sheridan
Road, Chicago, Illinois 60660, United States
| | - Václav Martínek
- Department
of Biochemistry, Faculty of Science, Charles University in Prague, Albertov 2030, 128 43 Prague 2, Czech Republic
- Department of Teaching and Didactics of Chemistry, Faculty of Science, Charles University in Prague, Albertov 3, 128 43 Prague 2, Czech Republic
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Stiborová M, Indra R, Moserová M, Šulc M, Hodek P, Frei E, Schmeiser HH, Arlt VM. NADPH- and NADH-dependent metabolism of and DNA adduct formation by benzo[ a]pyrene catalyzed with rat hepatic microsomes and cytochrome P450 1A1. MONATSHEFTE FUR CHEMIE 2016; 147:847-855. [PMID: 27110038 PMCID: PMC4828493 DOI: 10.1007/s00706-016-1713-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 02/11/2016] [Indexed: 11/11/2022]
Abstract
ABSTRACT Benzo[a]pyrene (BaP) is a human carcinogen that covalently binds to DNA after metabolic activation by cytochrome P450 (CYP) enzymes. Here we investigated the efficiencies of rat hepatic microsomes and rat recombinant CYP1A1 expressed with its reductase, NADPH:CYP oxidoreductase (POR), NADH:cytochrome b5 reductase, epoxide hydrolase and/or cytochrome b5 in Supersomes™ to metabolize this carcinogen. We also studied the effectiveness of coenzymes of two of the microsomal reductases, NADPH as a coenzyme of POR, and NADH as a coenzyme of NADH:cytochrome b5 reductase, to mediate BaP metabolism in these systems. Up to eight BaP metabolites and two DNA adducts were generated by the systems, both in the presence of NADPH and NADH. Among BaP metabolites, BaP-9,10-dihydrodiol, BaP-4,5-dihydrodiol, BaP-7,8-dihydrodiol, BaP-1,6-dione, BaP-3,6-dione, BaP-9-ol, BaP-3-ol, and a metabolite of unknown structure were formed by hepatic microsomes and rat CYP1A1. One of two DNA adducts formed by examined enzymatic systems (rat hepatic microsomes and rat CYP1A1) was characterized to be 10-(deoxyguanosin-N2-yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene (dG-N2-BPDE), while another adduct has similar chromatographic properties on polyethylaneimine-cellulose thin layer chromatography to a guanine adduct derived from reaction with 9-hydroxy-BaP-4,5-oxide. In the presence of either of the reductase cofactors tested, NADPH or NADH, cytochrome b5 stimulated CYP1A1-mediated formation of both BaP-DNA adducts. The results demonstrate that NADH can act as a sole electron donor for both the first and the second reduction of CYP1A1 during its reaction cycle catalyzing oxidation of BaP, and suggest that the NADH:cytochrome b5 reductase as the NADH-dependent reductase might substitute POR in this enzymatic system. GRAPHICAL ABSTRACT
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Affiliation(s)
- Marie Stiborová
- />Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Radek Indra
- />Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Michaela Moserová
- />Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Miroslav Šulc
- />Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Petr Hodek
- />Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Eva Frei
- />Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Heinz H. Schmeiser
- />Division of Radiopharmaceutical Chemistry, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Volker M. Arlt
- />Analytical and Environmental Sciences Division, MRC-PHE Centre for Environment and Health, King’s College London, London, SE1 9NH UK
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22
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Stiborová M, Moserová M, Mrízová I, Dračínská H, Martínek V, Indra R, Frei E, Adam V, Kizek R, Schmeiser HH, Kubáčková K, Arlt VM. Induced expression of microsomal cytochrome b5 determined at mRNA and protein levels in rats exposed to ellipticine, benzo[ a]pyrene, and 1-phenylazo-2-naphthol (Sudan I). MONATSHEFTE FUR CHEMIE 2016; 147:897-904. [PMID: 27110040 PMCID: PMC4828491 DOI: 10.1007/s00706-015-1636-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2015] [Accepted: 12/13/2015] [Indexed: 11/29/2022]
Abstract
ABSTRACT The microsomal protein cytochrome b5 , which is located in the membrane of the endoplasmic reticulum, has been shown to modulate many reactions catalyzed by cytochrome P450 (CYP) enzymes. We investigated the influence of exposure to the anticancer drug ellipticine and to two environmental carcinogens, benzo[a]pyrene (BaP) and 1-phenylazo-2-naphthol (Sudan I), on the expression of cytochrome b5 in livers of rats, both at the mRNA and protein levels. We also studied the effects of these compounds on their own metabolism and the formation of DNA adducts generated by their activation metabolite(s) in vitro. The relative amounts of cytochrome b5 mRNA, measured by real-time polymerase chain reaction analysis, were induced by the test compounds up to 11.7-fold in rat livers. Western blotting using antibodies raised against cytochrome b5 showed that protein expression was induced by up to sevenfold in livers of treated rats. Microsomes isolated from livers of exposed rats catalyzed the oxidation of ellipticine, BaP, and Sudan I and the formation of DNA adducts generated by their reactive metabolite(s) more effectively than hepatic microsomes isolated from control rats. All test compounds are known to induce CYP1A1. This induction is one of the reasons responsible for increased oxidation of these xenobiotics by microsomes. However, induction of cytochrome b5 can also contribute to their enhanced metabolism. GRAPHICAL ABSTRACT
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Affiliation(s)
- Marie Stiborová
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Michaela Moserová
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Iveta Mrízová
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Helena Dračínská
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Václav Martínek
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Radek Indra
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Eva Frei
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Vojtěch Adam
- Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University in Brno, 613 00 Brno, Czech Republic
| | - René Kizek
- Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University in Brno, 613 00 Brno, Czech Republic
| | - Heinz H Schmeiser
- Division of Radiopharmaceutical Chemistry, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Kateřina Kubáčková
- Department of Oncology, 2nd Faculty of Medicine, Charles University and University Hospital Motol, V Uvalu 84, 150 06 Prague 5, Czech Republic
| | - Volker M Arlt
- Analytical and Environmental Sciences Division, MRC-PHE Centre for Environment and Health, King's College London, London, SE1 9NH UK
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23
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Stiborová M, Bárta F, Levová K, Hodek P, Schmeiser HH, Arlt VM, Martínek V. A Mechanism of O-Demethylation of Aristolochic Acid I by Cytochromes P450 and Their Contributions to This Reaction in Human and Rat Livers: Experimental and Theoretical Approaches. Int J Mol Sci 2015; 16:27561-75. [PMID: 26593908 PMCID: PMC4661905 DOI: 10.3390/ijms161126047] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 10/30/2015] [Accepted: 11/05/2015] [Indexed: 01/30/2023] Open
Abstract
Aristolochic acid I (AAI) is a plant alkaloid causing aristolochic acid nephropathy, Balkan endemic nephropathy and their associated urothelial malignancies. AAI is detoxified by cytochrome P450 (CYP)-mediated O-demethylation to 8-hydroxyaristolochic acid I (aristolochic acid Ia, AAIa). We previously investigated the efficiencies of human and rat CYPs in the presence of two other components of the mixed-functions-oxidase system, NADPH:CYP oxidoreductase and cytochrome b₅, to oxidize AAI. Human and rat CYP1A are the major enzymes oxidizing AAI. Other CYPs such as CYP2C, 3A4, 2D6, 2E1, and 1B1, also form AAIa, but with much lower efficiency than CYP1A. Based on velocities of AAIa formation by examined CYPs and their expression levels in human and rat livers, here we determined the contributions of individual CYPs to AAI oxidation in these organs. Human CYP1A2 followed by CYP2C9, 3A4 and 1A1 were the major enzymes contributing to AAI oxidation in human liver, while CYP2C and 1A were most important in rat liver. We employed flexible in silico docking methods to explain the differences in AAI oxidation in the liver by human CYP1A1, 1A2, 2C9, and 3A4, the enzymes that all O-demethylate AAI, but with different effectiveness. We found that the binding orientations of the methoxy group of AAI in binding centers of the CYP enzymes and the energies of AAI binding to the CYP active sites dictate the efficiency of AAI oxidation. Our results indicate that utilization of experimental and theoretical methods is an appropriate study design to examine the CYP-catalyzed reaction mechanisms of AAI oxidation and contributions of human hepatic CYPs to this metabolism.
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Affiliation(s)
- Marie Stiborová
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, Prague 2 CZ-12843, Czech Republic.
| | - František Bárta
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, Prague 2 CZ-12843, Czech Republic.
| | - Kateřina Levová
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, Prague 2 CZ-12843, Czech Republic.
| | - Petr Hodek
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, Prague 2 CZ-12843, Czech Republic.
| | - Heinz H Schmeiser
- Division of Radiopharmaceutical Chemistry, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg 69120, Germany.
| | - Volker M Arlt
- Analytical and Environmental Sciences Division, MRC-PHE Centre for Environment and Health, King's College London, London SE1 9NH, UK.
| | - Václav Martínek
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, Prague 2 CZ-12843, Czech Republic.
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Ječmen T, Ptáčková R, Černá V, Dračínská H, Hodek P, Stiborová M, Hudeček J, Šulc M. Photo-initiated crosslinking extends mapping of the protein-protein interface to membrane-embedded portions of cytochromes P450 2B4 and b₅. Methods 2015; 89:128-37. [PMID: 26235815 DOI: 10.1016/j.ymeth.2015.07.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 07/27/2015] [Accepted: 07/28/2015] [Indexed: 01/17/2023] Open
Abstract
Protein-protein interactions play a central role in the regulation of many biochemical processes (e.g. the system participating in enzyme catalysis). Therefore, a deeper understanding of protein-protein interactions may contribute to the elucidation of many biologically important mechanisms. For this purpose, it is necessary to establish the composition and stoichiometry of supramolecular complexes and to identify the crucial portions of the interacting molecules. This study is devoted to structure-functional relationships in the microsomal Mixed Function Oxidase (MFO) complex, which is responsible for biotransformation of many hydrophobic endogenous compounds and xenobiotics. In particular, the cytochrome b5 interaction with MFO terminal oxygenase cytochrome P-450 (P450) was studied. To create photolabile probes suitable for this purpose, we prepared cytochrome b5 which had a photolabile diazirine analog of methionine (pMet) incorporated into the protein sequence, employing recombinant expression in Escherichia coli. In addition to wild-type cytochrome b5, where three methionines (Met) are located at positions 96, 126, and 131, six mutants containing only one Met in the sequence were designed and expressed (see Table 1). In these mutants, a single Met was engineered into the catalytic domain (at positions 23, 41, or 46), into the linker between the protein domains (at position 96), or into the membrane region (at positions 126 or 131). These mutants should confirm or exclude these portions of cytochrome b5 which are involved in the interaction with P450. After UV irradiation, the pMet group(s) in the photolabile cytochrome b5 probe was(were) activated, producing covalent crosslinks with the interacting parts of P450 2B4 in the close vicinity. The covalent complexes were analyzed by the "bottom up" approach with high-accuracy mass spectrometry. The analysis provided an identification of the contacts in the supramolecular complex with low structural resolution. We found that all the above-mentioned cytochrome b5 Met residues can form intermolecular crosslinks and thus participate in the interaction. In addition, our results indicate the existence of at least two P450:cytochrome b5 complexes which differ in the orientation of individual proteins. The results demonstrate the advantages of the photo-initiated crosslinking technique which is able to map the protein-protein interfaces not only in the solvent exposed regions, but also in the membrane-embedded segments (compared to a typical crosslinking approach which generally only identifies crosslinks in solvent exposed regions).
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Affiliation(s)
- Tomáš Ječmen
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic; Institute of Microbiology v.v.i., Academy of Sciences of the Czech Republic, Vídeňská 1083, CZ-14220 Prague 4, Czech Republic
| | - Renata Ptáčková
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic; Institute of Microbiology v.v.i., Academy of Sciences of the Czech Republic, Vídeňská 1083, CZ-14220 Prague 4, Czech Republic
| | - Věra Černá
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic
| | - Helena Dračínská
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic
| | - Petr Hodek
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic
| | - Marie Stiborová
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic
| | - Jiří Hudeček
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic
| | - Miroslav Šulc
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic; Institute of Microbiology v.v.i., Academy of Sciences of the Czech Republic, Vídeňská 1083, CZ-14220 Prague 4, Czech Republic.
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25
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Arlt VM, Henderson CJ, Wolf CR, Stiborová M, Phillips DH. The Hepatic Reductase Null (HRN™) and Reductase Conditional Null (RCN) mouse models as suitable tools to study metabolism, toxicity and carcinogenicity of environmental pollutants. Toxicol Res (Camb) 2015. [DOI: 10.1039/c4tx00116h] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
This review describes the applicability of the Hepatic Reductase Null (HRN) and Reductase Conditional Null (RCN) mouse models to study carcinogen metabolism.
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Affiliation(s)
- Volker M. Arlt
- Analytical and Environmental Sciences Division
- MRC-PHE Centre for Environment and Health
- King's College London
- London SE1 9NH
- UK
| | - Colin J. Henderson
- Division of Cancer Research
- Medical Research Institute
- Jacqui Wood Cancer Centre
- University of Dundee
- Dundee DD1 9SY
| | - C. Roland Wolf
- Division of Cancer Research
- Medical Research Institute
- Jacqui Wood Cancer Centre
- University of Dundee
- Dundee DD1 9SY
| | - Marie Stiborová
- Department of Biochemistry
- Faculty of Science
- Charles University
- 128 40 Prague 2
- Czech Republic
| | - David H. Phillips
- Analytical and Environmental Sciences Division
- MRC-PHE Centre for Environment and Health
- King's College London
- London SE1 9NH
- UK
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26
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Stiborová M, Černá V, Moserová M, Mrízová I, Arlt VM, Frei E. The anticancer drug ellipticine activated with cytochrome P450 mediates DNA damage determining its pharmacological efficiencies: studies with rats, Hepatic Cytochrome P450 Reductase Null (HRN™) mice and pure enzymes. Int J Mol Sci 2014; 16:284-306. [PMID: 25547492 PMCID: PMC4307247 DOI: 10.3390/ijms16010284] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Accepted: 12/17/2014] [Indexed: 12/30/2022] Open
Abstract
Ellipticine is a DNA-damaging agent acting as a prodrug whose pharmacological efficiencies and genotoxic side effects are dictated by activation with cytochrome P450 (CYP). Over the last decade we have gained extensive experience in using pure enzymes and various animal models that helped to identify CYPs metabolizing ellipticine. In this review we focus on comparison between the in vitro and in vivo studies and show a necessity of both approaches to obtain valid information on CYP enzymes contributing to ellipticine metabolism. Discrepancies were found between the CYP enzymes activating ellipticine to 13-hydroxy- and 12-hydroxyellipticine generating covalent DNA adducts and those detoxifying this drug to 9-hydroxy- and 7-hydroellipticine in vitro and in vivo. In vivo, formation of ellipticine-DNA adducts is dependent not only on expression levels of CYP3A, catalyzing ellipticine activation in vitro, but also on those of CYP1A that oxidize ellipticine in vitro mainly to the detoxification products. The finding showing that cytochrome b5 alters the ratio of ellipticine metabolites generated by CYP1A1/2 and 3A4 explained this paradox. Whereas the detoxification of ellipticine by CYP1A and 3A is either decreased or not changed by cytochrome b5, activation leading to ellipticine-DNA adducts increased considerably. We show that (I) the pharmacological effects of ellipticine mediated by covalent ellipticine-derived DNA adducts are dictated by expression levels of CYP1A, 3A and cytochrome b5, and its own potency to induce these enzymes in tumor tissues, (II) animal models, where levels of CYPs are either knocked out or induced are appropriate to identify CYPs metabolizing ellipticine in vivo, and (III) extrapolation from in vitro data to the situation in vivo is not always possible, confirming the need for these animal models.
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Affiliation(s)
- Marie Stiborová
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic.
| | - Věra Černá
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic.
| | - Michaela Moserová
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic.
| | - Iveta Mrízová
- Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic.
| | - Volker M Arlt
- Analytical and Environmental Sciences Division, MRC-PHE Centre for Environmental & Health, King's College London, 150 Stamford Street, London SE1 9NH, UK.
| | - Eva Frei
- Division of Preventive Oncology, National Center for Tumor Diseases, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
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27
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Formation of DNA adducts by ellipticine and its micellar form in rats - a comparative study. SENSORS 2014; 14:22982-97. [PMID: 25479328 PMCID: PMC4299049 DOI: 10.3390/s141222982] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 11/27/2014] [Accepted: 11/28/2014] [Indexed: 01/11/2023]
Abstract
The requirements for early diagnostics as well as effective treatment of cancer diseases have increased the pressure on development of efficient methods for targeted drug delivery as well as imaging of the treatment success. One of the most recent approaches covering the drug delivery aspects is benefitting from the unique properties of nanomaterials. Ellipticine and its derivatives are efficient anticancer compounds that function through multiple mechanisms. Formation of covalent DNA adducts after ellipticine enzymatic activation is one of the most important mechanisms of its pharmacological action. In this study, we investigated whether ellipticine might be released from its micellar (encapsulated) form to generate covalent adducts analogous to those formed by free ellipticine. The 32P-postlabeling technique was used as a useful imaging method to detect and quantify covalent ellipticine-derived DNA adducts. We compared the efficiencies of free ellipticine and its micellar form (the poly(ethylene oxide)-block-poly(allyl glycidyl ether) (PAGE-PEO) block copolymer, P 119 nanoparticles) to form ellipticine-DNA adducts in rats in vivo. Here, we demonstrate for the first time that treatment of rats with ellipticine in micelles resulted in formation of ellipticine-derived DNA adducts in vivo and suggest that a gradual release of ellipticine from its micellar form might produce the enhanced permeation and retention effect of this ellipticine-micellar delivery system.
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28
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Jeřábek P, Florián J, Stiborová M, Martínek V. Flexible docking-based molecular dynamics/steered molecular dynamics calculations of protein-protein contacts in a complex of cytochrome P450 1A2 with cytochrome b5. Biochemistry 2014; 53:6695-705. [PMID: 25313797 DOI: 10.1021/bi500814t] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Formation of transient complexes of cytochrome P450 (P450) with another protein of the endoplasmic reticulum membrane, cytochrome b5 (cyt b5), dictates the catalytic activities of several P450s. Therefore, we examined formation and binding modes of the complex of human P450 1A2 with cyt b5. Docking of soluble domains of these proteins was performed using an information-driven flexible docking approach implemented in HADDOCK. Stabilities of the five unique binding modes of the P450 1A2-cyt b5 complex yielded by HADDOCK were evaluated using explicit 10 ns molecular dynamics (MD) simulations in aqueous solution. Further, steered MD was used to compare the stability of the individual P450 1A2-cyt b5 binding modes. The best binding mode was characterized by a T-shaped mutual orientation of the porphyrin rings and a 10.7 Å distance between the two redox centers, thus satisfying the condition for a fast electron transfer. Mutagenesis studies and chemical cross-linking, which, in the absence of crystal structures, were previously used to deduce specific P450-cyt b5 interactions, indicated that the negatively charged convex surface of cyt b5 binds to the positively charged concave surface of P450. Our simulations further elaborate structural details of this interface, including nine ion pairs between R95, R100, R138, R362, K442, K455, and K465 side chains of P450 1A2 and E42, E43, E49, D65, D71, and heme propionates of cyt b5. The universal heme-centric system of internal coordinates was proposed to facilitate consistent classification of the orientation of the two porphyrins in any protein complex.
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Affiliation(s)
- Petr Jeřábek
- Department of Biochemistry, Faculty of Science, Charles University in Prague , Albertov 2030, 128 43 Prague 2, Czech Republic
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29
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Stiborová M, Moserová M, Černá V, Indra R, Dračínský M, Šulc M, Henderson CJ, Wolf CR, Schmeiser HH, Phillips DH, Frei E, Arlt VM. Cytochrome b5 and epoxide hydrolase contribute to benzo[a]pyrene-DNA adduct formation catalyzed by cytochrome P450 1A1 under low NADPH:P450 oxidoreductase conditions. Toxicology 2014; 318:1-12. [PMID: 24530354 DOI: 10.1016/j.tox.2014.02.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 01/31/2014] [Accepted: 02/04/2014] [Indexed: 10/25/2022]
Abstract
In previous studies we had administered benzo[a]pyrene (BaP) to genetically engineered mice (HRN) which do not express NADPH:cytochrome P450 oxidoreductase (POR) in hepatocytes and observed higher DNA adduct levels in livers of these mice than in wild-type mice. To elucidate the reason for this unexpected finding we have used two different settings for in vitro incubations; hepatic microsomes from control and BaP-pretreated HRN mice and reconstituted systems with cytochrome P450 1A1 (CYP1A1), POR, cytochrome b5, and epoxide hydrolase (mEH) in different ratios. In microsomes from BaP-pretreated mice, in which Cyp1a1 was induced, higher levels of BaP metabolites were formed, mainly of BaP-7,8-dihydrodiol. At a low POR:CYP1A1 ratio of 0.05:1 in the reconstituted system, the amounts of BaP diones and BaP-9-ol formed were essentially the same as at an equimolar ratio, but formation of BaP-3-ol was ∼ 1.6-fold higher. Only after addition of mEH were BaP dihydrodiols found. Two BaP-DNA adducts were formed in the presence of mEH, but only one when CYP1A1 and POR were present alone. At a ratio of POR:CYP1A1 of 0.05:1, addition of cytochrome b5 increased CYP1A1-mediated BaP oxidation to most of its metabolites indicating that cytochrome b5 participates in the electron transfer from NADPH to CYP1A1 required for enzyme activity of this CYP. BaP-9-ol was formed even by CYP1A1 reconstituted with cytochrome b5 without POR. Our results suggest that in livers of HRN mice Cyp1a1, cytochrome b5 and mEH can effectively activate BaP to DNA binding species, even in the presence of very low amounts of POR.
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Affiliation(s)
- Marie Stiborová
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic.
| | - Michaela Moserová
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Věra Černá
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Radek Indra
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Martin Dračínský
- Institute of Organic Chemistry and Biochemistry, v.v.i. Academy of Sciences, Flemingovo n. 2, 166 10 Prague 6, Czech Republic
| | - Miroslav Šulc
- Department of Biochemistry, Faculty of Science, Charles University, Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Colin J Henderson
- Division of Cancer Research, Medical Research Institute, Jacqui Wood Cancer Centre, University of Dundee, Dundee DD1 9SY, United Kingdom
| | - C Roland Wolf
- Division of Cancer Research, Medical Research Institute, Jacqui Wood Cancer Centre, University of Dundee, Dundee DD1 9SY, United Kingdom
| | - Heinz H Schmeiser
- Research Group Genetic Alterations in Carcinogenesis, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - David H Phillips
- Analytical and Environmental Sciences Division, MRC-PHE Centre for Environment and Health, King's College London, 150 Stamford Street, London SE1 9NH, United Kingdom
| | - Eva Frei
- Division of Preventive Oncology, National Center for Tumour Diseases, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Volker M Arlt
- Analytical and Environmental Sciences Division, MRC-PHE Centre for Environment and Health, King's College London, 150 Stamford Street, London SE1 9NH, United Kingdom
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Pyrethroid activity-based probes for profiling cytochrome P450 activities associated with insecticide interactions. Proc Natl Acad Sci U S A 2013; 110:19766-71. [PMID: 24248381 DOI: 10.1073/pnas.1320185110] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Pyrethroid insecticides are used to control diseases spread by arthropods. We have developed a suite of pyrethroid mimetic activity-based probes (PyABPs) to selectively label and identify P450s associated with pyrethroid metabolism. The probes were screened against pyrethroid-metabolizing and nonmetabolizing mosquito P450s, as well as rodent microsomes, to measure labeling specificity, plus cytochrome P450 oxidoreductase and b5 knockout mouse livers to validate P450 activation and establish the role for b5 in probe activation. Using PyABPs, we were able to profile active enzymes in rat liver microsomes and identify pyrethroid-metabolizing enzymes in the target tissue. These included P450s as well as related detoxification enzymes, notably UDP-glucuronosyltransferases, suggesting a network of associated pyrethroid-metabolizing enzymes, or "pyrethrome." Considering the central role P450s play in metabolizing insecticides, we anticipate that PyABPs will aid in the identification and profiling of P450s associated with insecticide pharmacology in a wide range of species, improving understanding of P450-insecticide interactions and aiding the development of unique tools for disease control.
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O'Sullivan EC, Miller CM, Deane FM, McCarthy FO. Emerging Targets in the Bioactivity of Ellipticines and Derivatives. STUDIES IN NATURAL PRODUCTS CHEMISTRY 2013. [DOI: 10.1016/b978-0-444-62615-8.00006-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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Rocha e Silva LF, Montoia A, Amorim RCN, Melo MR, Henrique MC, Nunomura SM, Costa MRF, Andrade Neto VF, Costa DS, Dantas G, Lavrado J, Moreira R, Paulo A, Pinto AC, Tadei WP, Zacardi RS, Eberlin MN, Pohlit AM. Comparative in vitro and in vivo antimalarial activity of the indole alkaloids ellipticine, olivacine, cryptolepine and a synthetic cryptolepine analog. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2012; 20:71-76. [PMID: 23092722 DOI: 10.1016/j.phymed.2012.09.008] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Revised: 07/17/2012] [Accepted: 09/06/2012] [Indexed: 06/01/2023]
Abstract
Indole alkaloids ellipticine (1), cryptolepine triflate (2a), rationally designed 11-(4-piperidinamino)cryptolepine hydrogen dichloride (2b) and olivacine (3) (an isomer of 1) were evaluated in vitro against Plasmodium falciparum and in vivo in Plasmodium berghei-infected mice. 1-3 inhibited P. falciparum (IC₅₀≤1.4 μM, order of activity: 2b>1>2a>3). In vitro toxicity to murine macrophages was evaluated and revealed selectivity indices (SI) of 10-12 for 2a and SI>2.8×10² for 1, 2b and 3. 1 administered orally at 50mg/kg/day was highly active against P. berghei (in vivo inhibition compared to untreated control (IVI)=100%, mean survival time (MST)>40 days, comparable activity to chloroquine control). 1 administered orally and subcutaneously was active at 10 mg/kg/day (IVI=70-77%; MST=27-29 days). 3 exhibited high oral activity at ≥50 mg/kg/day (IVI=90-97%, MST=23-27 days). Cryptolepine (2a) administered orally and subcutaneously exhibited moderate activity at 50mg/kg/day (IVI=43-63%, MST=24-25 days). At 50 mg/kg/day, 2b administered subcutaneously was lethal to infected mice (MST=3 days) and moderately active when administered orally (IVI=45-55%, MST=25 days). 1 and 3 are promising compounds for development of antimalarials.
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Affiliation(s)
- L F Rocha e Silva
- National Institute for Amazonian Research, Av. André Araújo 2936, Aleixo, 69060-001 Manaus, Amazonas, Brazil
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Arlt VM, Poirier MC, Sykes SE, John K, Moserova M, Stiborova M, Wolf CR, Henderson CJ, Phillips DH. Exposure to benzo[a]pyrene of Hepatic Cytochrome P450 Reductase Null (HRN) and P450 Reductase Conditional Null (RCN) mice: Detection of benzo[a]pyrene diol epoxide-DNA adducts by immunohistochemistry and 32P-postlabelling. Toxicol Lett 2012; 213:160-6. [PMID: 22759596 PMCID: PMC7477777 DOI: 10.1016/j.toxlet.2012.06.016] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Revised: 06/20/2012] [Accepted: 06/25/2012] [Indexed: 01/24/2023]
Abstract
Benzo[a]pyrene (BaP) is a widespread environmental carcinogen activated by cytochrome P450 (P450) enzymes. In Hepatic P450 Reductase Null (HRN) and Reductase Conditional Null (RCN) mice, P450 oxidoreductase (Por) is deleted specifically in hepatocytes, resulting in the loss of essentially all hepatic P450 function. Treatment of HRN mice with a single i.p. or oral dose of BaP (12.5 or 125mg/kg body weight) resulted in higher DNA adduct levels in liver (up to 10-fold) than in wild-type (WT) mice, indicating that hepatic P450s appear to be more important for BaP detoxification in vivo. Similar results were obtained in RCN mice. We tested whether differences between hepatocytes and non-hepatocytes in P450 activity may underlie the increased liver BaP-DNA binding in HRN mice. Cellular localisation by immunohistochemistry of BaP-DNA adducts showed that HRN mice have ample capacity for formation of BaP-DNA adducts in liver, indicating that the metabolic process does not result in the generation of a reactive species different from that formed in WT mice. However, increased protein expression of cytochrome b(5) in hepatic microsomes of HRN relative to WT mice suggests that cytochrome b(5) may modulate the P450-mediated bioactivation of BaP in HRN mice, partially substituting the function of Por.
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Affiliation(s)
- Volker M Arlt
- Analytical and Environmental Sciences Division, MRC-HPA Centre for Environment and Health, King's College London, London, United Kingdom.
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Ellipticine oxidation and DNA adduct formation in human hepatocytes is catalyzed by human cytochromes P450 and enhanced by cytochrome b5. Toxicology 2012; 302:233-41. [PMID: 22917556 DOI: 10.1016/j.tox.2012.08.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2012] [Revised: 08/05/2012] [Accepted: 08/06/2012] [Indexed: 11/24/2022]
Abstract
Ellipticine is an antineoplastic agent considered a pro-drug, the pharmacological and genotoxic effects of which are dependent on cytochrome P450 (CYP)- and/or peroxidase-mediated activation to covalent DNA adducts. We investigated whether ellipticine-DNA adducts are formed in human hepatic microsomes and human hepatocytes. We then identified which human CYPs oxidize ellipticine to metabolites forming DNA adducts and the effect of cytochrome b(5) on this oxidation. 13-Hydroxyellipticine, the metabolite forming the major ellipticine-DNA adduct, was generated mainly by CYP3A4 and 1A1, followed by CYP2D6>2C19>1B1>1A2>2E1 and >2C9. Cytochrome b(5) increased formation of this metabolite by human CYPs, predominantly by CYP1A1, 3A4, 1A2 and 2C19. Formation of 12-hydroxyellipticine is generated mainly by CYP2C19, followed by CYP2C9>3A4>2D6>2E1 and >2A6. Other CYPs were less active (CYP2C8 and 2B6) or did not oxidize ellipticine to this metabolite (CYP1A1, 1A2 and 1B1). CYP2D6 was the most efficient enzyme generating ellipticine N(2)-oxide. CYP3A4 and 1A1 in the presence of cytochrome b(5) are mainly responsible for bioactivation of ellipticine to DNA adduct 1 (formed by ellipticine-13-ylium from 13-hydroxyellipticine), while 12-hydroxyellipticine generated during the CYP2C19-mediated ellipticine oxidation is the predominant metabolite forming ellipticine-12-ylium that generates ellipticine-DNA adduct 2. These ellipticine-DNA adducts were also generated by human hepatic microsomes and in primary human hepatocytes exposed to ellipticine. Ellipticine is toxic to these hepatocytes, decreasing their viability; the IC(50) value of ellipticine in these cells was 0.7 μM. In liver CYP3A4 is the predominant ellipticine activating CYP species, which is expected to result in efficient metabolism after oral ingestion of ellipticine in humans.
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Abstract
Considerable support exists for the roles of metabolism in modulating the carcinogenic properties of chemicals. In particular, many of these compounds are pro-carcinogens that require activation to electrophilic forms to exert genotoxic effects. We systematically analyzed the existing literature on the metabolism of carcinogens by human enzymes, which has been developed largely in the past 25 years. The metabolism and especially bioactivation of carcinogens are dominated by cytochrome P450 enzymes (66% of bioactivations). Within this group, six P450s--1A1, 1A2, 1B1, 2A6, 2E1, and 3A4--accounted for 77% of the P450 activation reactions. The roles of these P450s can be compared with those estimated for drug metabolism and should be considered in issues involving enzyme induction, chemoprevention, molecular epidemiology, interindividual variations, and risk assessment.
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Stiborová M, Indra R, Moserová M, Černá V, Rupertová M, Martínek V, Eckschlager T, Kizek R, Frei E. Cytochrome b5 Increases Cytochrome P450 3A4-Mediated Activation of Anticancer Drug Ellipticine to 13-Hydroxyellipticine Whose Covalent Binding to DNA Is Elevated by Sulfotransferases and N,O-Acetyltransferases. Chem Res Toxicol 2012; 25:1075-85. [DOI: 10.1021/tx3000335] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Marie Stiborová
- Department of Biochemistry,
Faculty of Science, Charles University,
Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Radek Indra
- Department of Biochemistry,
Faculty of Science, Charles University,
Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Michaela Moserová
- Department of Biochemistry,
Faculty of Science, Charles University,
Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Věra Černá
- Department of Biochemistry,
Faculty of Science, Charles University,
Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Martina Rupertová
- Department of Biochemistry,
Faculty of Science, Charles University,
Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Václav Martínek
- Department of Biochemistry,
Faculty of Science, Charles University,
Albertov 2030, 128 40 Prague 2, Czech Republic
| | - Tomáš Eckschlager
- Department of Pediatric Hematology
and Oncology, Charles University and University Hospital Motol, Prague, Czech Republic
| | - René Kizek
- Department of Chemistry and Biochemistry,
Faculty of Agronomy, Mendel University,
Brno, Czech Republic
| | - Eva Frei
- Division
of Preventive Oncology,
National Center for Tumor Diseases, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
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