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Tentscher PR, Escher BI, Schlichting R, König M, Bramaz N, Schirmer K, von Gunten U. Toxic effects of substituted p-benzoquinones and hydroquinones in in vitro bioassays are altered by reactions with the cell assay medium. WATER RESEARCH 2021; 202:117415. [PMID: 34348209 DOI: 10.1016/j.watres.2021.117415] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 06/19/2021] [Accepted: 07/02/2021] [Indexed: 06/13/2023]
Abstract
Substituted para-benzoquinones and hydroquinones are ubiquitous transformation products that arise during oxidative water treatment of phenolic precursors, for example through ozonation or chlorination. The benzoquinone structural motive is associated with mutagenicity and carcinogenicity, and also with induction of the oxidative stress response through the Nrf2 pathway. For either endpoint, toxicological data for differently substituted compounds are scarce. In this study, oxidative stress response, as indicated by the AREc32 in vitro bioassay, was induced by differently substituted para-benzoquinones, but also by the corresponding hydroquinones. Bioassays that indicate defense against genotoxicity (p53RE-bla) and DNA repair activity (UmuC) were not activated by these compounds. Stability tests conducted under incubation conditions, but in the absence of cell lines, showed that tested para-benzoquinones reacted rapidly with constituents of the incubation medium. Compounds were abated already in phosphate buffer, but even faster in biological media, with reactions attributed to amino- and thiol-groups of peptides, proteins, and free amino acids. The products of these reactions were often the corresponding substituted hydroquinones. Conversely, differently substituted hydroquinones were quantitatively oxidized to p-benzoquinones over the course of the incubation. The observed induction of the oxidative stress response was attributed to hydroquinones that are presumably oxidized to benzoquinones inside the cells. Despite the instability of the tested compounds in the incubation medium, the AREc32 in vitro bioassay could be used as an unspecific sum parameter to detect para-benzoquinones and hydroquinones in oxidatively treated waters.
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Affiliation(s)
- Peter R Tentscher
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Duebendorf CH-8600, Switzerland; Department of Chemistry and Bioscience, Aalborg University, Aalborg 9220, Denmark
| | - Beate I Escher
- Department of Cell Toxicology, UFZ - Helmholtz Centre for Environmental Research, Leipzig 04318, Germany; Center for Applied Geoscience, Eberhard Karls University of Tübingen, Schnarrenbergstr. 94-96, Tübingen 72076, Germany
| | - Rita Schlichting
- Department of Cell Toxicology, UFZ - Helmholtz Centre for Environmental Research, Leipzig 04318, Germany
| | - Maria König
- Department of Cell Toxicology, UFZ - Helmholtz Centre for Environmental Research, Leipzig 04318, Germany
| | - Nadine Bramaz
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Duebendorf CH-8600, Switzerland
| | - Kristin Schirmer
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Duebendorf CH-8600, Switzerland; Department of Environmental Systems Science, ETH Zürich, Zürich CH-8092, Switzerland; Civil and Environmental Engineering (ENAC), School of Architecture, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland
| | - Urs von Gunten
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Duebendorf CH-8600, Switzerland; Civil and Environmental Engineering (ENAC), School of Architecture, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015, Switzerland.
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Berthelet J, Michail C, Bui LC, Le Coadou L, Sirri V, Wang L, Dulphy N, Dupret JM, Chomienne C, Guidez F, Rodrigues-Lima F. The benzene hematotoxic and reactive metabolite 1,4-benzoquinone impairs the activity of the histone methyltransferase SETD2 and causes aberrant H3K36 trimethylation (H3K36me3). Mol Pharmacol 2021; 100:283-294. [PMID: 34266924 DOI: 10.1124/molpharm.121.000303] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 06/28/2021] [Indexed: 11/22/2022] Open
Abstract
Human SETD2 is the unique histone methyltransferase that generates H3K36me3, an epigenetic mark that plays a key role in normal hematopoiesis. Interestingly, recurrent-inactivating mutations of SETD2 and aberrant H3K36 trimethylation (H3K36me3) are increasingly reported to be involved in hematopoietic malignancies. Benzene (BZ) is an ubiquitous environmental pollutant and carcinogen that causes leukemia. The leukemogenic properties of BZ depend on its biotransformation in the bone marrow into oxidative metabolites in particular 1,4-benzoquinone (BQ). This hematotoxic metabolite can form DNA and protein adducts that result in the damage and the alteration of cellular processes. Recent studies suggest that BZ-depend leukemogenesis could depend on epigenetic perturbations notably aberrant histone methylation. We investigated whether H3K36 trimethylation by SETD2 could be impacted by BZ and its hematotoxic metabolites. Herein, we show that BQ, the major leukemogenic metabolite of BZ, inhibits irreversibly the human histone methyltransferase SETD2 resulting in decreased H3K36 trimethylation (H3K36me3). Our mechanistic studies further indicate that the BQ-dependent inactivation of SETD2 is due to covalent binding of BQ to reactive Zn-finger cysteines within the catalytic domain of the enzyme. The formation of these quinoprotein adducts results in loss of enzyme activity and protein cross-links/oligomers. Experiments conducted in hematopoietic cells confirm that exposure to BQ results in the formation of SETD2 cross-links/oligomers and concomitant loss of H3K36me3 in cells. Taken together, our data indicate that BQ, a major hematotoxic metabolite of BZ could contribute to BZ-dependent leukemogenesis by perturbing the functions of SETD2, an histone lysine methyltransferase of hematopoietic relevance. Significance Statement Benzoquinone is a major leukemogenic metabolite of benzene. Dysregulation of histone methyltransferase is involved in hematopoietic malignancies. We found that benzoquinone irreversibly impairs SETD2, a histone H3K36 methyltransferase that plays a key role in hematopoiesis. Benzoquinone forms covalent adducts on Zn-finger cysteines within the catalytic site leading to loss of activity, protein cross-links/oligomers and concomitant decrease of H3K36me3 histone mark. Our data provide evidence that a leukemogenic metabolite of benzene can impair a key epigenetic enzyme.
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Affiliation(s)
| | | | | | | | | | - Li Wang
- The First Affiliated Hospital of Chongqing Medical University, China
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Vann KR, Oviatt AA, Osheroff N. Topoisomerase II Poisons: Converting Essential Enzymes into Molecular Scissors. Biochemistry 2021; 60:1630-1641. [PMID: 34008964 PMCID: PMC8209676 DOI: 10.1021/acs.biochem.1c00240] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The extensive length, compaction, and interwound nature of DNA, together with its controlled and restricted movement in eukaryotic cells, create a number of topological issues that profoundly affect all of the functions of the genetic material. Topoisomerases are essential enzymes that modulate the topological structure of the double helix, including the regulation of DNA under- and overwinding and the removal of tangles and knots from the genome. Type II topoisomerases alter DNA topology by generating a transient double-stranded break in one DNA segment and allowing another segment to pass through the DNA gate. These enzymes are involved in a number of critical nuclear processes in eukaryotic cells, such as DNA replication, transcription, and recombination, and are required for proper chromosome structure and segregation. However, because type II topoisomerases generate double-stranded breaks in the genetic material, they also are intrinsically dangerous enzymes that have the capacity to fragment the genome. As a result of this dualistic nature, type II topoisomerases are the targets for a number of widely prescribed anticancer drugs. This article will describe the structure and catalytic mechanism of eukaryotic type II topoisomerases and will go on to discuss the actions of topoisomerase II poisons, which are compounds that stabilize DNA breaks generated by the type II enzyme and convert these essential enzymes into "molecular scissors." Topoisomerase II poisons represent a broad range of structural classes and include anticancer drugs, dietary components, and environmental chemicals.
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Affiliation(s)
- Kendra R Vann
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | - Alexandria A Oviatt
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | - Neil Osheroff
- Departments of Biochemistry and Medicine (Hematology/Oncology), Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
- VA Tennessee Valley Healthcare System, Nashville, Tennessee 37212, United States
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4
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Abstract
1,2-Naphthoquinone, a secondary metabolite of naphthalene, is an environmental pollutant found in diesel exhaust particles that displays cytotoxic and genotoxic properties. Because many quinones have been shown to act as topoisomerase II poisons, the effects of this compound on DNA cleavage mediated by human topoisomerase IIα and IIβ were examined. The compound increased the levels of double-stranded DNA breaks generated by both enzyme isoforms and did so better than a series of naphthoquinone derivatives. Furthermore, 1,2-naphthoquinone was a more efficacious poison against topoisomerase IIα than IIβ. Topoisomerase II poisons can be classified as interfacial (which interact noncovalently at the enzyme-DNA interface and increase DNA cleavage by blocking ligation) or covalent (which adduct the protein and increase DNA cleavage by closing the N-terminal gate of the enzyme). Therefore, experiments were performed to determine the mechanistic basis for the actions of 1,2-naphthoquinone. In contrast to results with etoposide (an interfacial poison), the activity of 1,2-naphthoquinone against topoisomerase IIα was abrogated in the presence of sulfhydryl and reducing agents. Moreover, the compound inhibited cleavage activity when incubated with the enzyme prior to the addition of DNA and induced virtually no cleavage with the catalytic core of the enzyme. It also induced stable covalent topoisomerase IIα-DNA cleavage complexes and was a partial inhibitor of DNA ligation. Findings were also consistent with 1,2-naphthoquinone acting as a covalent poison of topoisomerase IIβ; however, mechanistic studies with this isoform were less conclusive. Whereas the activity of 1,2-naphthoquinone was blocked in the presence of a sulfhydryl reagent, it was much less sensitive to the presence of a reducing agent. Furthermore, the reduced form of 1,2-naphthoquinone, 1,2-dihydroxynaphthalene, displayed high activity against the β isoform. Taken together, results suggest that 1,2-naphthoquinone increases topoisomerase II-mediated double-stranded DNA scission (at least in part) by acting as a covalent poison of the human type II enzymes.
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Affiliation(s)
- Jessica A. Collins
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
| | - Neil Osheroff
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
- Department of Medicine (Hematology/Oncology), Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
- VA Tennessee Valley Healthcare System, Nashville, Tennessee 37212, United States
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Porras G, Chassagne F, Lyles JT, Marquez L, Dettweiler M, Salam AM, Samarakoon T, Shabih S, Farrokhi DR, Quave CL. Ethnobotany and the Role of Plant Natural Products in Antibiotic Drug Discovery. Chem Rev 2021; 121:3495-3560. [PMID: 33164487 PMCID: PMC8183567 DOI: 10.1021/acs.chemrev.0c00922] [Citation(s) in RCA: 133] [Impact Index Per Article: 44.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The crisis of antibiotic resistance necessitates creative and innovative approaches, from chemical identification and analysis to the assessment of bioactivity. Plant natural products (NPs) represent a promising source of antibacterial lead compounds that could help fill the drug discovery pipeline in response to the growing antibiotic resistance crisis. The major strength of plant NPs lies in their rich and unique chemodiversity, their worldwide distribution and ease of access, their various antibacterial modes of action, and the proven clinical effectiveness of plant extracts from which they are isolated. While many studies have tried to summarize NPs with antibacterial activities, a comprehensive review with rigorous selection criteria has never been performed. In this work, the literature from 2012 to 2019 was systematically reviewed to highlight plant-derived compounds with antibacterial activity by focusing on their growth inhibitory activity. A total of 459 compounds are included in this Review, of which 50.8% are phenolic derivatives, 26.6% are terpenoids, 5.7% are alkaloids, and 17% are classified as other metabolites. A selection of 183 compounds is further discussed regarding their antibacterial activity, biosynthesis, structure-activity relationship, mechanism of action, and potential as antibiotics. Emerging trends in the field of antibacterial drug discovery from plants are also discussed. This Review brings to the forefront key findings on the antibacterial potential of plant NPs for consideration in future antibiotic discovery and development efforts.
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Affiliation(s)
- Gina Porras
- Center for the Study of Human Health, Emory University, 1557 Dickey Dr., Atlanta, Georgia 30322
| | - François Chassagne
- Center for the Study of Human Health, Emory University, 1557 Dickey Dr., Atlanta, Georgia 30322
| | - James T. Lyles
- Center for the Study of Human Health, Emory University, 1557 Dickey Dr., Atlanta, Georgia 30322
| | - Lewis Marquez
- Molecular and Systems Pharmacology Program, Laney Graduate School, Emory University, 615 Michael St., Whitehead 115, Atlanta, Georgia 30322
| | - Micah Dettweiler
- Department of Dermatology, Emory University, 615 Michael St., Whitehead 105L, Atlanta, Georgia 30322
| | - Akram M. Salam
- Molecular and Systems Pharmacology Program, Laney Graduate School, Emory University, 615 Michael St., Whitehead 115, Atlanta, Georgia 30322
| | - Tharanga Samarakoon
- Emory University Herbarium, Emory University, 1462 Clifton Rd NE, Room 102, Atlanta, Georgia 30322
| | - Sarah Shabih
- Center for the Study of Human Health, Emory University, 1557 Dickey Dr., Atlanta, Georgia 30322
| | - Darya Raschid Farrokhi
- Center for the Study of Human Health, Emory University, 1557 Dickey Dr., Atlanta, Georgia 30322
| | - Cassandra L. Quave
- Center for the Study of Human Health, Emory University, 1557 Dickey Dr., Atlanta, Georgia 30322
- Emory University Herbarium, Emory University, 1462 Clifton Rd NE, Room 102, Atlanta, Georgia 30322
- Department of Dermatology, Emory University, 615 Michael St., Whitehead 105L, Atlanta, Georgia 30322
- Molecular and Systems Pharmacology Program, Laney Graduate School, Emory University, 615 Michael St., Whitehead 115, Atlanta, Georgia 30322
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Zhang W, Berthelet J, Michail C, Bui LC, Gou P, Liu R, Duval R, Renault J, Dupret JM, Guidez F, Chomienne C, Rodrigues Lima F. Human CREBBP acetyltransferase is impaired by etoposide quinone, an oxidative and leukemogenic metabolite of the anticancer drug etoposide through modification of redox-sensitive zinc-finger cysteine residues. Free Radic Biol Med 2021; 162:27-37. [PMID: 33278510 DOI: 10.1016/j.freeradbiomed.2020.11.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 11/22/2020] [Accepted: 11/23/2020] [Indexed: 12/25/2022]
Abstract
Etoposide is an extensively prescribed anticancer drug that, unfortunately, causes therapy-related leukemia. The mechanisms by which etoposide induces secondary hematopoietic malignancies are poorly documented. However, etoposide-related leukemogenesis is known to depend on oxidative metabolites of etoposide, notably etoposide quinone, that can react with protein cysteine residues such as in topoisomerases II. CREBBP is a major histone acetyltransferase that functions mainly as a transcriptional co-activator. This epigenetic enzyme is considered as a tumor suppressor that plays a major role in hematopoiesis. Genetic alterations affecting CREBBP activity are highly common in hematopoietic malignancies. We report here that CREBBP is impaired by etoposide quinone. Molecular and kinetic analyses show that this inhibition occurs through the rapid and covalent (kinhib = 16.102 M-1. s-1) adduction of etoposide quinone with redox sensitive cysteine residues within the RING and PHD Zn2+-fingers of CREBBP catalytic core leading to subsequent release of Zn2+. In agreement with these findings, experiments conducted in cells and in mice treated with etoposide showed irreversible inhibition of endogenous CREBBP activity and decreased H3K18 and H3K27 acetylation. As shown for topoisomerases II, our work thus suggests that the leukemogenic metabolite etoposide quinone can impair the epigenetic CREBBP acetyltransferase through reaction with redox sensitive cysteine residues.
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Affiliation(s)
- Wenchao Zhang
- Université de Paris, BFA, UMR 8251, CNRS, F-75013, Paris, France
| | - Jérémy Berthelet
- Université de Paris, BFA, UMR 8251, CNRS, F-75013, Paris, France; Université de Paris, CEDC, UMR 7216, CNRS, F-75013, Paris, France
| | | | - Linh-Chi Bui
- Université de Paris, BFA, UMR 8251, CNRS, F-75013, Paris, France
| | - Panhong Gou
- Université de Paris, Institut de Recherche Saint-Louis, UMRS 1131, INSERM, F-75010, Paris, France
| | - Rongxing Liu
- Université de Paris, BFA, UMR 8251, CNRS, F-75013, Paris, France
| | - Romain Duval
- Université de Paris, BIGR, UMRS 1134, INSERM, F-75015, Paris, France
| | - Justine Renault
- Université de Paris, BFA, UMR 8251, CNRS, F-75013, Paris, France
| | | | - Fabien Guidez
- Université de Paris, Institut de Recherche Saint-Louis, UMRS 1131, INSERM, F-75010, Paris, France
| | - Christine Chomienne
- Université de Paris, Institut de Recherche Saint-Louis, UMRS 1131, INSERM, F-75010, Paris, France; Service de Biologie Cellulaire, Assistance Publique des Hôpitaux de Paris (AP-HP), Hôpital Saint Louis, Paris, France
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7
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Waugh TM, Masters J, Aliev AE, Marson CM. Monocyclic Quinone Structure-Activity Patterns: Synthesis of Catalytic Inhibitors of Topoisomerase II with Potent Antiproliferative Activity. ChemMedChem 2019; 15:114-124. [PMID: 31778038 DOI: 10.1002/cmdc.201900548] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 10/28/2019] [Indexed: 12/12/2022]
Abstract
The monocyclic 1,4-benzoquinone, HU-331, the direct oxidation product of cannabidiol, inhibits the catalytic activity of topoisomerase II but without inducing DNA strand breaks or generating free radicals, and unlike many fused-ring quinones exhibits minimal cardiotoxicity. Thus, monocyclic quinones have potential as anticancer agents, and investigation of the structural origins of their biological activity is warranted. New syntheses of cannabidiol and (±)-HU-331 are here reported. Integrated synthetic protocols afforded a wide range of polysubstituted resorcinol derivatives; many of the corresponding novel 2-hydroxy-1,4-benzoquinone derivatives are potent inhibitors of the catalytic activity of topoisomerase II, some more so than HU-331, whose monoterpene unit replaced by a 3-cycloalkyl unit conferred increased antiproliferative properties in cell lines with IC50 values extending below 1 mM, and greater stability in solution than HU-331. The principal pharmacophore of quinones related to HU-331 was identified. Selected monocyclic quinones show potential for the development of new anticancer agents.
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Affiliation(s)
- Thomas M Waugh
- Department of Chemistry, University College London Christopher Ingold Laboratories, 20 Gordon Street, London, WC1H OAJ, UK
| | - John Masters
- Prostate Cancer Research Centre Research Department of Urology Charles Bell House, University College London, 67-75 Riding House Street, London, W1 W 7EJ, UK
| | - Abil E Aliev
- Department of Chemistry, University College London Christopher Ingold Laboratories, 20 Gordon Street, London, WC1H OAJ, UK
| | - Charles M Marson
- Department of Chemistry, University College London Christopher Ingold Laboratories, 20 Gordon Street, London, WC1H OAJ, UK
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8
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Keck JM, Conner JD, Wilson JT, Jiang X, Lisic EC, Deweese JE. Clarifying the Mechanism of Copper(II) α-(N)-Heterocyclic Thiosemicarbazone Complexes on DNA Topoisomerase IIα and IIβ. Chem Res Toxicol 2019; 32:2135-2143. [PMID: 31512855 DOI: 10.1021/acs.chemrestox.9b00311] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Topoisomerase II is a nuclear enzyme involved in the maintenance of DNA and is an effective anticancer drug target. However, several clinical topoisomerase II-targeted agents display significant off-target toxicities and adverse events. Thus, it is important to continue characterizing compounds with activity against topoisomerase II. We previously analyzed α-(N)-heterocyclic thiosemicarbazone copper(II) complexes against human topoisomerase IIα (TOP2A), but humans also express topoisomerase IIβ (TOP2B), which has distinct functional roles. Therefore, we examined two α-(N)-heterocyclic thiosemicarbazone copper [Cu(II)] complexes for activity against TOP2B in a purified system. The Cu(II) complexes, Cu(APY-ETSC)Cl and Cu(BZP-ETSC)Cl, were examined using plasmid DNA cleavage, supercoiled DNA relaxation, enzyme inactivation, protein cross-linking, DNA ligation, and ATP hydrolysis assays with TOP2B to determine whether these compounds act similarly against both enzymes. Both of the Cu(II) thiosemicarbazone (Cu-TSC) complexes we tested disrupted the function of TOP2B in a way similar to the effect on TOP2A. In particular, TOP2B DNA cleavage activity is increased in the presence of these compounds, while the relaxation and ATPase activities are inhibited. Further, both Cu-TSCs stabilize the N-terminal DNA clamp of TOP2A and TOP2B and rapidly inactivate TOP2B when the compounds are present before DNA. Our data provide evidence that the Cu-TSC complexes we tested utilize a similar mechanism against both isoforms of the enzyme. This mechanism may involve interaction with the ATPase domain of TOP2A and TOP2B outside of the ATP binding pocket. Additionally, these data support a model of TOP2 function where the ATPase domain communicates with the DNA cleavage/ligation domain.
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Affiliation(s)
- J Myles Keck
- Department of Pharmaceutical Sciences , Lipscomb University College of Pharmacy and Health Sciences , Nashville , Tennessee 37204-3951 , United States
| | - Jennifer D Conner
- Department of Chemistry , Tennessee Technological University , Cookeville , Tennessee 38505 , United States
| | - James T Wilson
- Department of Pharmaceutical Sciences , Lipscomb University College of Pharmacy and Health Sciences , Nashville , Tennessee 37204-3951 , United States
| | - Xiaohua Jiang
- Department of Chemistry , Tennessee Technological University , Cookeville , Tennessee 38505 , United States
| | - Edward C Lisic
- Department of Chemistry , Tennessee Technological University , Cookeville , Tennessee 38505 , United States
| | - Joseph E Deweese
- Department of Pharmaceutical Sciences , Lipscomb University College of Pharmacy and Health Sciences , Nashville , Tennessee 37204-3951 , United States.,Department of Biochemistry , Vanderbilt University School of Medicine , Nashville , Tennessee 37232-0146 , United States
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9
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Holmes TH, Winn LM. DNA Damage and Perturbed Topoisomerase IIα as a Target of 1,4-Benzoquinone Toxicity in Murine Fetal Liver Cells. Toxicol Sci 2019; 171:339-346. [PMID: 31340051 DOI: 10.1093/toxsci/kfz158] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 06/28/2019] [Accepted: 07/11/2019] [Indexed: 01/10/2023] Open
Abstract
Benzene is a ubiquitous environmental pollutant. Recent studies have shown a link between the development of childhood leukemias and maternal benzene exposure, suggesting that these leukemias may be initiated in utero. Benzene crosses the placental barrier however the mechanisms behind in utero benzene toxicity have not been well elucidated. This study is the first to show that the benzene metabolite, benzoquinone (BQ), perturbs fetal topoisomerase IIα (Topo IIα), an enzyme essential for DNA repair. Using cultured murine CD-1 fetal liver cells, this study shows that Topo IIα activity decreases following 24 hours of exposure to BQ (12.5 and 15.625 µM), with the 12.5 µM confirmed to disrupt the c-kit+Lin-Sca-1-Il7rα- population of cells in culture. Pre-treatment with the antioxidant, N-acetylcysteine did not prevent the inhibtion of Topo IIα by BQ. An increase in Topo IIα-DNA covalent adducts was detected following 24-hour exposures to BQ (12.5 and 50 µM). Interestingly, BQ (12.5 µM) exposure did not significantly increase levels of 4-hydroxynonenal (4-HNE), a marker of oxidative stress after 24 hours. However, increased levels of the double-stranded DNA break marker γH2AX were detected following 24 hours of BQ exposure, confirming that Topo IIα-induced breaks are increased in BQ treated cells. This study shows that fetal Topo IIα is perturbed by BQ and suggests that this protein is a target of benzene and may be implicated with in utero benzene toxicity.
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Affiliation(s)
- Trent H Holmes
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Louise M Winn
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada.,School of Environmental Studies, Queen's University, Kingston, Ontario, Canada
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10
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Duval R, Bui LC, Mathieu C, Nian Q, Berthelet J, Xu X, Haddad I, Vinh J, Dupret JM, Busi F, Guidez F, Chomienne C, Rodrigues-Lima F. Benzoquinone, a leukemogenic metabolite of benzene, catalytically inhibits the protein tyrosine phosphatase PTPN2 and alters STAT1 signaling. J Biol Chem 2019; 294:12483-12494. [PMID: 31248982 DOI: 10.1074/jbc.ra119.008666] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 06/21/2019] [Indexed: 12/12/2022] Open
Abstract
Protein tyrosine phosphatase, nonreceptor type 2 (PTPN2) is mainly expressed in hematopoietic cells, where it negatively regulates growth factor and cytokine signaling. PTPN2 is an important regulator of hematopoiesis and immune/inflammatory responses, as evidenced by loss-of-function mutations of PTPN2 in leukemia and lymphoma and knockout mice studies. Benzene is an environmental chemical that causes hematological malignancies, and its hematotoxicity arises from its bioactivation in the bone marrow to electrophilic metabolites, notably 1,4-benzoquinone, a major hematotoxic benzene metabolite. Although the molecular bases for benzene-induced leukemia are not well-understood, it has been suggested that benzene metabolites alter topoisomerases II function and thereby significantly contribute to leukemogenesis. However, several studies indicate that benzene and its hematotoxic metabolites may also promote the leukemogenic process by reacting with other targets and pathways. Interestingly, alterations of cell-signaling pathways, such as Janus kinase (JAK)/signal transducer and activator of transcription (STAT), have been proposed to contribute to benzene-induced malignant blood diseases. We show here that 1,4-benzoquinone directly impairs PTPN2 activity. Mechanistic and kinetic experiments with purified human PTPN2 indicated that this impairment results from the irreversible formation (k inact = 645 m-1·s-1) of a covalent 1,4-benzoquinone adduct at the catalytic cysteine residue of the enzyme. Accordingly, cell experiments revealed that 1,4-benzoquinone exposure irreversibly inhibits cellular PTPN2 and concomitantly increases tyrosine phosphorylation of STAT1 and expression of STAT1-regulated genes. Our results provide molecular and cellular evidence that 1,4-benzoquinone covalently modifies key signaling enzymes, implicating it in benzene-induced malignant blood diseases.
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Affiliation(s)
- Romain Duval
- Université de Paris, BFA, UMR 8251, CNRS, F-75013 Paris, France
| | - Linh-Chi Bui
- Université de Paris, BFA, UMR 8251, CNRS, F-75013 Paris, France
| | - Cécile Mathieu
- Université de Paris, BFA, UMR 8251, CNRS, F-75013 Paris, France
| | - Qing Nian
- Université de Paris, BFA, UMR 8251, CNRS, F-75013 Paris, France
| | | | - Ximing Xu
- Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
| | - Iman Haddad
- ESPCI Paris, PSL Université, USR 3149, CNRS, F-75005 Paris, France
| | - Joelle Vinh
- ESPCI Paris, PSL Université, USR 3149, CNRS, F-75005 Paris, France
| | | | - Florent Busi
- Université de Paris, BFA, UMR 8251, CNRS, F-75013 Paris, France
| | - Fabien Guidez
- Université de Paris, Institut de Recherche Saint-Louis, UMRS 1131, INSERM, F-75010 Paris, France
| | - Christine Chomienne
- Université de Paris, Institut de Recherche Saint-Louis, UMRS 1131, INSERM, F-75010 Paris, France; Service de Biologie Cellulaire, Assistance Publique des Hôpitaux de Paris (AP-HP), Hôpital Saint Louis, F-75010 Paris, France
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11
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Rozanov D, Cheltsov A, Nilsen A, Boniface C, Forquer I, Korkola J, Gray J, Tyner J, Tognon CE, Mills GB, Spellman P. Targeting mitochondria in cancer therapy could provide a basis for the selective anti-cancer activity. PLoS One 2019; 14:e0205623. [PMID: 30908483 PMCID: PMC6433232 DOI: 10.1371/journal.pone.0205623] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 02/25/2019] [Indexed: 12/29/2022] Open
Abstract
To determine the target of the recently identified lead compound NSC130362 that is responsible for its selective anti-cancer efficacy and safety in normal cells, structure-activity relationship (SAR) studies were conducted. First, NSC13062 was validated as a starting compound for the described SAR studies in a variety of cell-based viability assays. Then, a small library of 1,4-naphthoquinines (1,4-NQs) and quinoline-5,8-diones was tested in cell viability assays using pancreatic cancer MIA PaCa-2 cells and normal human hepatocytes. The obtained data allowed us to select a set of both non-toxic compounds that preferentially induced apoptosis in cancer cells and toxic compounds that induced apoptosis in both cancer and normal cells. Anti-cancer activity of the selected non-toxic compounds was confirmed in viability assays using breast cancer HCC1187 cells. Consequently, the two sets of compounds were tested in multiple cell-based and in vitro activity assays to identify key factors responsible for the observed activity. Inhibition of the mitochondrial electron transfer chain (ETC) is a key distinguishing activity between the non-toxic and toxic compounds. Finally, we developed a mathematical model that was able to distinguish these two sets of compounds. The development of this model supports our conclusion that appropriate quantitative SAR (QSAR) models have the potential to be employed to develop anti-cancer compounds with improved potency while maintaining non-toxicity to normal cells.
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Affiliation(s)
- Dmitri Rozanov
- Department of Molecular and Medical Genetics, Knight Cancer Institute, Oregon Health and Science University, Portland, Oregon, United States of America
- * E-mail:
| | - Anton Cheltsov
- Q-MOL LLC, San Diego, California, United States of America
| | - Aaron Nilsen
- Medicinal Chemistry Core, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Christopher Boniface
- Department of Molecular and Medical Genetics, Knight Cancer Institute, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Isaac Forquer
- Chemistry Department, Portland State University, Portland, Oregon, United States of America
| | - James Korkola
- Department of Biomedical Engineering, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Joe Gray
- Department of Biomedical Engineering, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Jeffrey Tyner
- Department of Cell, Developmental and Cancer Biology, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Cristina E. Tognon
- Department of Cell, Developmental and Cancer Biology, Oregon Health and Science University, Portland, Oregon, United States of America
- Howard Hughes Medical Institute, Portland, Oregon, United States of America
- Division of Hematology & Medical Oncology, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Gordon B. Mills
- Department of Cell, Developmental and Cancer Biology, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Paul Spellman
- Department of Molecular and Medical Genetics, Knight Cancer Institute, Oregon Health and Science University, Portland, Oregon, United States of America
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12
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Mahalapbutr P, Chusuth P, Kungwan N, Chavasiri W, Wolschann P, Rungrotmongkol T. Molecular recognition of naphthoquinone-containing compounds against human DNA topoisomerase IIα ATPase domain: A molecular modeling study. J Mol Liq 2017. [DOI: 10.1016/j.molliq.2017.10.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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13
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Combination of Near Infrared Light-Activated Photodynamic Therapy Mediated by Indocyanine Green with Etoposide to Treat Non-Small-Cell Lung Cancer. Cancers (Basel) 2017; 9:cancers9060063. [PMID: 28587258 PMCID: PMC5483882 DOI: 10.3390/cancers9060063] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 06/01/2017] [Indexed: 11/17/2022] Open
Abstract
Indocyanine green (ICG) has been reported as a potential near-infrared (NIR) photosensitizer for photodynamic therapy (PDT) of cancer. However the application of ICG-mediated PDT is both intrinsically and physiologically limited. Here we report a combination of ICG-PDT with a chemotherapy drug etoposide (VP-16), aiming to enhance the anticancer efficacy, to circumvent limitations of PDT using ICG, and to reduce side effects of VP-16. We found in controlled in vitro cell-based assays that this combination is effective in killing non-small-cell lung cancer cells (NSCLC, A549 cell line). We also found that the combination of ICG-PDT and VP-16 exhibits strong synergy in killing non-small-cell lung cancer cells partially through inducing more DNA double-strand breaks (DSBs), while it has a much weaker synergy in killing human normal cells (GM05757). Furthermore, by studying the treatment sequence dependence and the cytotoxicity of laser-irradiated mixtures of ICG and VP-16, we found that the observed synergy involves direct/indirect reactions between ICG and VP-16. We further propose that there exists an electron transfer reaction between ICG and VP-16 under irradiation. This study therefore shows the anticancer efficacy of ICG-PDT combined with VP-16. These findings suggest that ICG-mediated PDT may be applied in combination with the chemotherapy drug VP-16 to treat some cancers, especially the non-small-cell lung cancer.
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14
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Vann KR, Ekiz G, Zencir S, Bedir E, Topcu Z, Osheroff N. Effects of Secondary Metabolites from the Fungus Septofusidium berolinense on DNA Cleavage Mediated by Human Topoisomerase IIα. Chem Res Toxicol 2016; 29:415-20. [PMID: 26894873 DOI: 10.1021/acs.chemrestox.6b00009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Two metabolites from the ascomycete fungus Septofusidium berolinense were recently identified as having antineoplastic activity [Ekiz et al. (2015) J. Antibiot. , DOI: 10.1038/ja.2015.84]. However, the basis for this activity is not known. One of the compounds [3,6-dihydroxy-2-propylbenzaldehyde (GE-1)] is a hydroquinone, and the other [2-hydroxymethyl-3-propylcyclohexa-2,5-diene-1,4-dione (GE-2)] is a quinone. Because some hydroquinones and quinones act as topoisomerase II poisons, the effects of GE-1 and GE-2 on DNA cleavage mediated by human topoisomerase IIα were assessed. GE-2 enhanced DNA cleavage ∼4-fold and induced scission with a site specificity similar to that of the anticancer drug etoposide. Similar to other quinone-based topoisomerase II poisons, GE-2 displayed several hallmark characteristics of covalent topoisomerase II poisons, including (1) the inability to poison a topoisomerase IIα construct that lacks the N-terminal domain, (2) the inhibition of DNA cleavage when the compound was incubated with the enzyme prior to the addition of plasmid, and (3) the loss of poisoning activity in the presence of a reducing agent. In contrast to GE-2, GE-1 did not enhance DNA cleavage mediated by topoisomerase IIα except at very high concentrations. However, the activity and potency of the metabolite were dramatically enhanced under oxidizing conditions. These results suggest that topoisomerase IIα may play a role in mediating the cytotoxic effects of these fungal metabolites.
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Affiliation(s)
| | | | - Sevil Zencir
- Department of Medical Biology, Faculty of Medicine, Pamukkale University , 20070 Denizli, Turkey
| | | | | | - Neil Osheroff
- VA Tennessee Valley Healthcare System , Nashville, Tennessee 37212, United States
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15
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Sinha BK, Mason RP. IS METABOLIC ACTIVATION OF TOPOISOMERASE II POISONS IMPORTANT IN THE MECHANISM OF CYTOTOXICITY? ACTA ACUST UNITED AC 2015; 6. [PMID: 31171989 DOI: 10.4172/2157-7609.1000186] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The antitumor drugs doxorubicin and etoposide, a phodophyllotoxin derivative, are clinically active for the treatment of human malignancies. Because of their extreme effectiveness in the clinic, their modes of actions have been the subject of intense research for over several decades both in the laboratory and in the clinic. It has been found that both doxorubicin and etoposide (VP-16) act on topoisomerase II, induce DNA cleavage, and form double-strand breaks, causing tumor cell death. However, both of these drugs also undergo extensive metabolism in tumor cells and in vivo to various reactive intermediates that bind covalently to cellular DNA and proteins. Moreover, both drugs are metabolized to reactive free radicals that induce lipid peroxidation and DNA damage. However, the role of drug activation in the mechanism of cytotoxicity remains poorly defined. In this review, we critically evaluate the significance of metabolic activation of doxorubicin and etoposide in the mechanism of tumor cytotoxicity.
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Affiliation(s)
- Birandra K Sinha
- Immunity, Inflammation and Disease Laboratory, National Institutes of Environmental Health Sciences, NIH, Research Triangle, Park, North Carolina, USA
| | - Ronald P Mason
- Immunity, Inflammation and Disease Laboratory, National Institutes of Environmental Health Sciences, NIH, Research Triangle, Park, North Carolina, USA
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16
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Vann KR, Sedgeman CA, Gopas J, Golan-Goldhirsh A, Osheroff N. Effects of Olive Metabolites on DNA Cleavage Mediated by Human Type II Topoisomerases. Biochemistry 2015; 54:4531-41. [PMID: 26132160 PMCID: PMC4520624 DOI: 10.1021/acs.biochem.5b00162] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
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Several
naturally occurring dietary polyphenols with chemopreventive
or anticancer properties are topoisomerase II poisons. To identify
additional phytochemicals that enhance topoisomerase II-mediated DNA
cleavage, a library of 341 Mediterranean plant extracts was screened
for activity against human topoisomerase IIα. An extract from Phillyrea latifolia L., a member of the olive tree family,
displayed high activity against the human enzyme. On the basis of
previous metabolomics studies, we identified several polyphenols (hydroxytyrosol,
oleuropein, verbascoside, tyrosol, and caffeic acid) as potential
candidates for topoisomerase II poisons. Of these, hydroxytyrosol,
oleuropein, and verbascoside enhanced topoisomerase II-mediated DNA
cleavage. The potency of these olive metabolites increased 10–100-fold
in the presence of an oxidant. Hydroxytyrosol, oleuropein, and verbascoside
displayed hallmark characteristics of covalent topoisomerase II poisons.
(1) The activity of the metabolites was abrogated by a reducing agent.
(2) Compounds inhibited topoisomerase II activity when they were incubated
with the enzyme prior to the addition of DNA. (3) Compounds were unable
to poison a topoisomerase IIα construct that lacked the N-terminal
domain. Because hydroxytyrosol, oleuropein, and verbascoside are broadly
distributed across the olive family, extracts from the leaves, bark,
and fruit of 11 olive tree species were tested for activity against
human topoisomerase IIα. Several of the extracts enhanced enzyme-mediated
DNA cleavage. Finally, a commercial olive leaf supplement and extra
virgin olive oils pressed from a variety of Olea europea subspecies enhanced DNA cleavage mediated by topoisomerase IIα.
Thus, olive metabolites appear to act as topoisomerase II poisons
in complex formulations intended for human dietary consumption.
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Affiliation(s)
| | | | - Jacob Gopas
- ∥Department of Microbiology, Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.,⊥Department of Oncology, Soroka University Medical Center, Beer Sheva 84105, Israel
| | - Avi Golan-Goldhirsh
- @The Jacob Blaustein Institutes for Desert Research (BIDR), French Associates Institute for Agriculture and Biotechnology of Drylands, Ben-Gurion University of the Negev, Sede Boqer Campus, Beer Sheva 84990, Israel
| | - Neil Osheroff
- §VA Tennessee Valley Healthcare System, Nashville, Tennessee 37212, United States
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17
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Roberts NB, Curtis SA, Milan AM, Ranganath LR. The Pigment in Alkaptonuria Relationship to Melanin and Other Coloured Substances: A Review of Metabolism, Composition and Chemical Analysis. JIMD Rep 2015; 24:51-66. [PMID: 26093627 DOI: 10.1007/8904_2015_453] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 04/30/2015] [Accepted: 05/04/2015] [Indexed: 01/02/2023] Open
Abstract
The pigments found in plants, animals and humic substances are well described and classified. In humans considerable progress has been made with the main pigment melanin in defining its biochemistry, the different types and function. However, analytical techniques to show these differences in vivo are still not readily available. NMR and IR spectroscopy are relatively insensitive and reveal only major structural differences. Techniques utilising MS are useful in determining elemental content but require further studies to optimise conditions for accurate mass analysis. How the components may be structurally organised seems to be the most problematic with scanning TEM and the improved FTIR of use in this respect. As regards understanding the nature of the pigment related to HGA seen in patients with Alkaptonuria (AKU), it is still thought of as a melaninlike pigment simply because of its colour and likewise thought to be a polymer of undetermined size. It is important that detailed analysis be carried out to define more accurately this pigment. However, observations suggest it to be the same as the HGA-derived pigment, pyomelanin, produced by bacteria and containing both quinone and phenolic groups. The interesting developments in alkaptonuria will be to understand how such a polymer can cause such profound collagen and connective tissue damage and how best to reverse this process.
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Affiliation(s)
- N B Roberts
- Department of Clinical Biochemistry and Metabolic Medicine, The Royal Liverpool and Broadgreen University Hospitals Trust, Liverpool, L7 8XP, UK.
| | - S A Curtis
- Department of Clinical Biochemistry and Metabolic Medicine, The Royal Liverpool and Broadgreen University Hospitals Trust, Liverpool, L7 8XP, UK
| | - A M Milan
- Department of Clinical Biochemistry and Metabolic Medicine, The Royal Liverpool and Broadgreen University Hospitals Trust, Liverpool, L7 8XP, UK
| | - L R Ranganath
- Department of Clinical Biochemistry and Metabolic Medicine, The Royal Liverpool and Broadgreen University Hospitals Trust, Liverpool, L7 8XP, UK
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18
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Andres SN, Schellenberg MJ, Wallace BD, Tumbale P, Williams RS. Recognition and repair of chemically heterogeneous structures at DNA ends. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2015; 56:1-21. [PMID: 25111769 PMCID: PMC4303525 DOI: 10.1002/em.21892] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2014] [Accepted: 07/28/2014] [Indexed: 05/13/2023]
Abstract
Exposure to environmental toxicants and stressors, radiation, pharmaceutical drugs, inflammation, cellular respiration, and routine DNA metabolism all lead to the production of cytotoxic DNA strand breaks. Akin to splintered wood, DNA breaks are not "clean." Rather, DNA breaks typically lack DNA 5'-phosphate and 3'-hydroxyl moieties required for DNA synthesis and DNA ligation. Failure to resolve damage at DNA ends can lead to abnormal DNA replication and repair, and is associated with genomic instability, mutagenesis, neurological disease, ageing and carcinogenesis. An array of chemically heterogeneous DNA termini arises from spontaneously generated DNA single-strand and double-strand breaks (SSBs and DSBs), and also from normal and/or inappropriate DNA metabolism by DNA polymerases, DNA ligases and topoisomerases. As a front line of defense to these genotoxic insults, eukaryotic cells have accrued an arsenal of enzymatic first responders that bind and protect damaged DNA termini, and enzymatically tailor DNA ends for DNA repair synthesis and ligation. These nucleic acid transactions employ direct damage reversal enzymes including Aprataxin (APTX), Polynucleotide kinase phosphatase (PNK), the tyrosyl DNA phosphodiesterases (TDP1 and TDP2), the Ku70/80 complex and DNA polymerase β (POLβ). Nucleolytic processing enzymes such as the MRE11/RAD50/NBS1/CtIP complex, Flap endonuclease (FEN1) and the apurinic endonucleases (APE1 and APE2) also act in the chemical "cleansing" of DNA breaks to prevent genomic instability and disease, and promote progression of DNA- and RNA-DNA damage response (DDR and RDDR) pathways. Here, we provide an overview of cellular first responders dedicated to the detection and repair of abnormal DNA termini.
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Affiliation(s)
- Sara N Andres
- Laboratory of Structural Biology, National Institute of Environmental Health Sciences, NIH, DHHS, North Carolina
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19
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Regal KM, Mercer SL, Deweese JE. HU-331 is a catalytic inhibitor of topoisomerase IIα. Chem Res Toxicol 2014; 27:2044-51. [PMID: 25409338 DOI: 10.1021/tx500245m] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Topoisomerases are essential enzymes that are involved in DNA metabolism. Topoisomerase II generates transient DNA strand breaks that are stabilized by anticancer drugs, such as doxorubicin, causing an accumulation of DNA damage. However, doxorubicin causes cardiac toxicity and, like etoposide and other topoisomerase II-targeted agents, can induce DNA damage, resulting in secondary cancers. The cannabinoid quinone HU-331 has been identified as a potential anticancer drug that demonstrates more potency in cancer cells with less off-target toxicity than that of doxorubicin. Reports indicate that HU-331 does not promote cell death via apoptosis, cell cycle arrest, caspase activation, or DNA strand breaks. However, the precise mechanism of action is poorly understood. We employed biochemical assays to study the mechanism of action of HU-331 against purified topoisomerase IIα. These assays examined DNA binding, cleavage, ligation, relaxation, and ATPase activities of topoisomerase IIα. Our results demonstrate that HU-331 inhibits topoisomerase IIα-mediated DNA relaxation at micromolar levels. We find that HU-331 does not induce DNA strand breaks in vitro. When added prior to the DNA substrate, HU-331 blocks DNA cleavage and relaxation activities of topoisomerase IIα in a redox-sensitive manner. The action of HU-331 can be blocked, but not reversed, by the presence of dithiothreitol. Our results also show that HU-331 inhibits the ATPase activity of topoisomerase IIα using a noncompetitive mechanism. Preliminary binding studies also indicate that HU-331 decreases the ability of topoisomerase IIα to bind DNA. In summary, HU-331 inhibits relaxation activity without poisoning DNA cleavage. This action is sensitive to reducing agents and appears to involve noncompetitive inhibition of the ATPase activity and possibly inhibition of DNA binding. These studies provide a promising foundation for the exploration of HU-331 as a catalytic inhibitor of topoisomerase IIα.
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Affiliation(s)
- Kellie M Regal
- Department of Pharmaceutical Sciences, Lipscomb University College of Pharmacy and Health Sciences , Nashville, Tennessee 37204-3951, United States
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20
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Lindsey RH, Pendleton M, Ashley RE, Mercer SL, Deweese JE, Osheroff N. Catalytic core of human topoisomerase IIα: insights into enzyme-DNA interactions and drug mechanism. Biochemistry 2014; 53:6595-602. [PMID: 25280269 PMCID: PMC4204876 DOI: 10.1021/bi5010816] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Coordination between the N-terminal gate and the catalytic core of topoisomerase II allows the proper capture, cleavage, and transport of DNA during the catalytic cycle. Because the activities of these domains are tightly linked, it has been difficult to discern their individual contributions to enzyme-DNA interactions and drug mechanism. To further address the roles of these domains, we analyzed the activity of the catalytic core of human topoisomerase IIα. The catalytic core and the wild-type enzyme both maintained higher levels of cleavage with negatively (as compared to positively) supercoiled plasmid, indicating that the ability to distinguish supercoil handedness is embedded within the catalytic core. However, the catalytic core alone displayed little ability to cleave DNA substrates that did not intrinsically provide the enzyme with a transport segment (i.e., substrates that did not contain crossovers). Finally, in contrast to interfacial topoisomerase II poisons, covalent poisons did not enhance DNA cleavage mediated by the catalytic core. This distinction allowed us to further characterize the mechanism of etoposide quinone, a drug metabolite that functions primarily as a covalent poison. Etoposide quinone retained some ability to enhance DNA cleavage mediated by the catalytic core, indicating that it still can function as an interfacial poison. These results further define the distinct contributions of the N-terminal gate and the catalytic core to topoisomerase II function. The catalytic core senses the handedness of DNA supercoils during cleavage, while the N-terminal gate is critical for capturing the transport segment and for the activity of covalent poisons.
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Affiliation(s)
- R Hunter Lindsey
- Department of Biochemistry, ‡Department of Pharmacology, and §Department of Medicine (Hematology/Oncology), Vanderbilt University School of Medicine , Nashville, Tennessee 37232-0146, United States
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21
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Smith NA, Byl JAW, Mercer SL, Deweese JE, Osheroff N. Etoposide quinone is a covalent poison of human topoisomerase IIβ. Biochemistry 2014; 53:3229-36. [PMID: 24766193 PMCID: PMC4033626 DOI: 10.1021/bi500421q] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
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Etoposide is a topoisomerase II poison
that is utilized to treat
a broad spectrum of human cancers. Despite its wide clinical use,
2–3% of patients treated with etoposide eventually develop
treatment-related acute myeloid leukemias (t-AMLs) characterized by
rearrangements of the MLL gene. The molecular basis
underlying the development of these t-AMLs is not well understood;
however, previous studies have implicated etoposide metabolites (i.e.,
etoposide quinone) and topoisomerase IIβ in the leukemogenic
process. Although interactions between etoposide quinone and topoisomerase
IIα have been characterized, the effects of the drug metabolite
on the activity of human topoisomerase IIβ have not been reported.
Thus, we examined the ability of etoposide quinone to poison human
topoisomerase IIβ. The quinone induced ∼4 times more
enzyme-mediated DNA cleavage than did the parent drug. Furthermore,
the potency of etoposide quinone was ∼2 times greater against
topoisomerase IIβ than it was against topoisomerase IIα,
and the drug reacted ∼2–4 times faster with the β
isoform. Etoposide quinone induced a higher ratio of double- to single-stranded
breaks than etoposide, and its activity was less dependent on ATP.
Whereas etoposide acts as an interfacial topoisomerase II poison,
etoposide quinone displayed all of the hallmarks of a covalent poison:
the activity of the metabolite was abolished by reducing agents, and
the compound inactivated topoisomerase IIβ when it was incubated
with the enzyme prior to the addition of DNA. These results are consistent
with the hypothesis that etoposide quinone contributes to etoposide-related
leukemogenesis through an interaction with topoisomerase IIβ.
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Affiliation(s)
- Nicholas A Smith
- Departments of †Biochemistry, ‡Medicine (Hematology/Oncology), and §Pharmacology, Vanderbilt University School of Medicine , Nashville, Tennessee 37232-0146, United States
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22
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Ashley RE, Osheroff N. Natural products as topoisomerase II poisons: effects of thymoquinone on DNA cleavage mediated by human topoisomerase IIα. Chem Res Toxicol 2014; 27:787-93. [PMID: 24650156 PMCID: PMC4033629 DOI: 10.1021/tx400453v] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
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The
seeds of Nigella sativa (often
referred to as black seed) have long been utilized as a medicinal
herb in Middle Eastern, Northern African, and Indian cultures. Historically,
black seed has been used to treat a variety of illnesses associated
with inflammation. More recent studies have found that it induces
apoptosis and displays anticancer activity in animal and cellular
models. The major bioactive compound of black seed is thymoquinone,
which shares structural features with 1,4-benzoquinone and other covalent
topoisomerase II poisons. Because a number of anticancer drugs target
type II topoisomerases, we determined the effects of thymoquinone
and a series of related quinones on human topoisomerase IIα.
Thymoquinone enhanced enzyme-mediated DNA cleavage ∼5-fold,
which is similar to the increase seen with the anticancer drug etoposide.
In order to enhance cleavage, compounds had to have at least two positions
available for acylation. Furthermore, activity was decreased by the
inclusion of electron-donating groups or bulky substituents. As predicted
for a covalent topoisomerase II poison, the activity of thymoquinone
(and related compounds) was abrogated by the addition of a reducing
agent. Also, thymoquinone inhibited topoisomerase IIα activity
when incubated with the enzyme prior to the addition of DNA. Cleavage
complexes formed in the presence of the compound were stable for at
least 8 h. Lastly, black seed extract and black seed oil both increased
levels of enzyme-mediated DNA cleavage, suggesting that thymoquinone
is active even in more complex herbal formulations. These findings
indicate that thymoquinone can be added to the growing list of dietary
and medicinal natural products with activity against human type II
topoisomerases.
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Affiliation(s)
- Rachel E Ashley
- Departments of †Biochemistry and ‡Medicine (Hematology/Oncology), Vanderbilt University School of Medicine , Nashville, Tennessee 37232-0146, United States
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23
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Ketron AC, Osheroff N. Phytochemicals as Anticancer and Chemopreventive Topoisomerase II Poisons. PHYTOCHEMISTRY REVIEWS : PROCEEDINGS OF THE PHYTOCHEMICAL SOCIETY OF EUROPE 2014; 13:19-35. [PMID: 24678287 PMCID: PMC3963363 DOI: 10.1007/s11101-013-9291-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Phytochemicals are a rich source of anticancer drugs and chemopreventive agents. Several of these chemicals appear to exert at least some of their effects through interactions with topoisomerase II, an essential enzyme that regulates DNA supercoiling and removes knots and tangles from the genome. Topoisomerase II-active phytochemicals function by stabilizing covalent protein-cleaved DNA complexes that are intermediates in the catalytic cycle of the enzyme. As a result, these compounds convert topoisomerase II to a cellular toxin that fragments the genome. Because of their mode of action, they are referred to as topoisomerase II poisons as opposed to catalytic inhibitors. The first sections of this article discuss DNA topology, the catalytic cycle of topoisomerase II, and the two mechanisms (interfacial vs. covalent) by which different classes of topoisomerase II poisons alter enzyme activity. Subsequent sections discuss the effects of several phytochemicals on the type II enzyme, including demethyl-epipodophyllotoxins (semisynthetic anticancer drugs) as well as flavones, flavonols, isoflavones, catechins, isothiocyanates, and curcumin (dietary chemopreventive agents). Finally, the leukemogenic potential of topoisomerase II-targeted phytochemicals is described.
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Affiliation(s)
- Adam C. Ketron
- Department of Biochemistry and the Vanderbilt Institute of Chemical Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232 USA
| | - Neil Osheroff
- Departments of Biochemistry and Medicine (Hematology/Oncology) and the Vanderbilt Institute of Chemical Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232 USA
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24
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Pendleton M, Lindsey RH, Felix CA, Grimwade D, Osheroff N. Topoisomerase II and leukemia. Ann N Y Acad Sci 2014; 1310:98-110. [PMID: 24495080 DOI: 10.1111/nyas.12358] [Citation(s) in RCA: 141] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Type II topoisomerases are essential enzymes that modulate DNA under- and overwinding, knotting, and tangling. Beyond their critical physiological functions, these enzymes are the targets for some of the most widely prescribed anticancer drugs (topoisomerase II poisons) in clinical use. Topoisomerase II poisons kill cells by increasing levels of covalent enzyme-cleaved DNA complexes that are normal reaction intermediates. Drugs such as etoposide, doxorubicin, and mitoxantrone are frontline therapies for a variety of solid tumors and hematological malignancies. Unfortunately, their use also is associated with the development of specific leukemias. Regimens that include etoposide or doxorubicin are linked to the occurrence of acute myeloid leukemias that feature rearrangements at chromosomal band 11q23. Similar rearrangements are seen in infant leukemias and are associated with gestational diets that are high in naturally occurring topoisomerase II-active compounds. Finally, regimens that include mitoxantrone and epirubicin are linked to acute promyelocytic leukemias that feature t(15;17) rearrangements. The first part of this article will focus on type II topoisomerases and describe the mechanism of enzyme and drug action. The second part will discuss how topoisomerase II poisons trigger chromosomal breaks that lead to leukemia and potential approaches for dissociating the actions of drugs from their leukemogenic potential.
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Affiliation(s)
- Maryjean Pendleton
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee
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Uc-Cachón AH, Borges-Argáez R, Said-Fernández S, Vargas-Villarreal J, González-Salazar F, Méndez-González M, Cáceres-Farfán M, Molina-Salinas GM. Naphthoquinones isolated from Diospyros anisandra exhibit potent activity against pan-resistant first-line drugs Mycobacterium tuberculosis strains. Pulm Pharmacol Ther 2013; 27:114-20. [PMID: 23968826 DOI: 10.1016/j.pupt.2013.08.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 08/04/2013] [Accepted: 08/09/2013] [Indexed: 10/26/2022]
Abstract
BACKGROUND AND OBJECTIVES The recent emergence of multidrug-resistant (MDR), extensively drug-resistant (XDR), and totally drug-resistant (TDR) Mycobacterium tuberculosis (MTB) strains have further complicated the control of tuberculosis (TB). There is an urgent need of new molecules candidates to be developed as novel, active, and less toxic anti-tuberculosis (anti-TB) drugs. Medicinal plants have been an excellent source of leads for the development of drugs, particularly as anti-infective agents. In previous studies, the non-polar extract of Diospyros anisandra showed potent anti-TB activity, and three monomeric and five dimeric naphthoquinones have been obtained. In this study, we performed bioguided chemical fractionation and the isolation of eight naphthoquinones from D. anisandra and their evaluation of anti-TB and cytotoxic activities against mammalian cells. METHODS The n-hexane crude extract from the stem bark of the plant was obtained by maceration and liquid-liquid fractionation. The isolation of naphthoquinones was carried out by chromatographic methods and identified by gas chromatography and mass spectroscopy data analysis. Anti-TB activity was evaluated against two strains of MTB (H37Rv) susceptible to all five first-line anti-TB drugs and a clinical isolate that is resistant to these medications (pan-resistant, CIBIN 99) by measuring the minimal inhibitory concentration (MIC). Cytotoxicity of naphthoquinones was estimated against two mammalian cells, Vero line and primary cultures of human peripheral blood mononuclear (PBMC) cells, and their selectivity index (SI) was determined. RESULTS Plumbagin and its dimers maritinone and 3,3'-biplumbagin showed the strongest activity against both MTB strains (MIC = 1.56-3.33 μg/mL). The bioactivity of maritinone and 3,3'-biplumbagin were 32 times more potent than rifampicin against the pan-resistant strain, and both dimers showed to be non-toxic against PBMC and Vero cells. The SI of maritinone and 3,3'-biplumbagin on Vero cells was 74.34 and 194.11 against sensitive and pan-resistant MTB strains, respectively. CONCLUSION Maritinone and 3,3'-biplumbagin possess a very interesting potential for development as new drugs against M. tuberculosis, mainly resistant profile strains.
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Affiliation(s)
- Andrés Humberto Uc-Cachón
- Unidad de Biotecnología del Centro de Investigación Científica de Yucatán A.C., Calle 43, No. 130, Col. Chuburná de Hidalgo, CP 97200 Mérida, Yucatán, Mexico.
| | - Rocío Borges-Argáez
- Unidad de Biotecnología del Centro de Investigación Científica de Yucatán A.C., Calle 43, No. 130, Col. Chuburná de Hidalgo, CP 97200 Mérida, Yucatán, Mexico.
| | - Salvador Said-Fernández
- División de Biología Celular y Molecular, Centro de Investigación Biomédica del Noreste, IMSS, San Luis Potosí y 2 de Abril, Col. Independencia, CP 65720 Monterrey, Nuevo León, Mexico.
| | - Javier Vargas-Villarreal
- División de Biología Celular y Molecular, Centro de Investigación Biomédica del Noreste, IMSS, San Luis Potosí y 2 de Abril, Col. Independencia, CP 65720 Monterrey, Nuevo León, Mexico.
| | - Francisco González-Salazar
- División de Biología Celular y Molecular, Centro de Investigación Biomédica del Noreste, IMSS, San Luis Potosí y 2 de Abril, Col. Independencia, CP 65720 Monterrey, Nuevo León, Mexico; Departamento de Ciencias Básicas, División de Ciencia de la Salud, Universidad de Monterrey, Ave. Ignacio Morones Prieto 4500 Pte., CP 66238 San Pedro Garza García, Nuevo León, Mexico.
| | - Martha Méndez-González
- Unidad de Recursos Naturales del Centro de Investigación Científica de Yucatán A.C., Calle 43, No. 130, Col. Chuburná de Hidalgo, CP 97200 Mérida, Yucatán, Mexico.
| | - Mirbella Cáceres-Farfán
- Unidad de Biotecnología del Centro de Investigación Científica de Yucatán A.C., Calle 43, No. 130, Col. Chuburná de Hidalgo, CP 97200 Mérida, Yucatán, Mexico.
| | - Gloria María Molina-Salinas
- División de Biología Celular y Molecular, Centro de Investigación Biomédica del Noreste, IMSS, San Luis Potosí y 2 de Abril, Col. Independencia, CP 65720 Monterrey, Nuevo León, Mexico.
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Jacob DA, Gibson EG, Mercer SL, Deweese JE. Etoposide catechol is an oxidizable topoisomerase II poison. Chem Res Toxicol 2013; 26:1156-8. [PMID: 23863110 DOI: 10.1021/tx400205n] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Topoisomerase II regulates DNA topology by generating transient double-stranded breaks. The anticancer drug etoposide targets topoisomerase II and is associated with the formation of secondary leukemias in patients. The quinone and catechol metabolites of etoposide may contribute to strand breaks that trigger leukemic translocations. To further analyze the characteristics of etoposide metabolites, we extend our previous analysis of etoposide quinone to the catechol. We demonstrate that the catechol is ∼2-3-fold more potent than etoposide and under oxidative reaction conditions induces high levels of double-stranded DNA cleavage. These results support a role for etoposide catechol in contributing to therapy-induced DNA damage.
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Affiliation(s)
- David A Jacob
- Department of Pharmaceutical Sciences, Lipscomb University College of Pharmacy and Health Sciences, Nashville, Tennessee 37204-3951, USA
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27
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Timmel MA, Byl JAW, Osheroff N. Epimerization of green tea catechins during brewing does not affect the ability to poison human type II topoisomerases. Chem Res Toxicol 2013; 26:622-8. [PMID: 23514406 DOI: 10.1021/tx4000667] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
(-)-Epigallocatechin gallate (EGCG) is the most abundant and biologically active polyphenol in green tea (Camellia sinensis) leaves, and many of its cellular effects are consistent with its actions as a topoisomerase II poison. In contrast to genistein and several related bioflavonoids that act as interfacial poisons, EGCG was the first bioflavonoid shown to act as a covalent topoisomerase II poison. Although studies routinely examine the effects of dietary phytochemicals on enzyme and cellular systems, they often fail to consider that many compounds are altered during cooking or cellular metabolism. To this point, the majority of EGCG and related catechins in green tea leaves are epimerized during the brewing process. Epimerization inverts the stereochemistry of the bond that bridges the B- and C-rings and converts EGCG to (-)-gallocatechin gallate (GCG). Consequently, a significant proportion of EGCG that is ingested during the consumption of green tea is actually GCG. Therefore, the effects of GCG and related epimerized green tea catechins on human topoisomerase IIα and IIβ were characterized. GCG increased levels of DNA cleavage mediated by both enzyme isoforms with an activity that was similar to that of EGCG. GCG acted primarily by inhibiting the ability of topoisomerase IIα and IIβ to ligate cleaved DNA. Several lines of evidence indicate that GCG functions as a covalent topoisomerase II poison that adducts the enzyme. Finally, epimerization did not affect the reactivity of the chemical substituents (the three hydroxyl groups on the B-ring) that were required for enzyme poisoning. Thus, the activity of covalent topoisomerase II poisons appears to be less sensitive to stereochemical changes than interfacial poisons.
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Affiliation(s)
- M Anne Timmel
- Departments of †Biochemistry and ‡Medicine (Hematology/Oncology), Vanderbilt University School of Medicine , Nashville, Tennessee 37232-0146, United States
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Karkare S, Chung TTH, Collin F, Mitchenall LA, McKay AR, Greive SJ, Meyer JJM, Lall N, Maxwell A. The naphthoquinone diospyrin is an inhibitor of DNA gyrase with a novel mechanism of action. J Biol Chem 2012; 288:5149-56. [PMID: 23275348 PMCID: PMC3576119 DOI: 10.1074/jbc.m112.419069] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Tuberculosis and other bacterial diseases represent a significant threat to human health. The DNA topoisomerases are excellent targets for chemotherapy, and DNA gyrase in particular is a well-validated target for antibacterial agents. Naphthoquinones (e.g. diospyrin and 7-methyljuglone) have been shown to have therapeutic potential, particularly against Mycobacterium tuberculosis. We have found that these compounds are inhibitors of the supercoiling reaction catalyzed by M. tuberculosis gyrase and other gyrases. Our evidence strongly suggests that the compounds bind to the N-terminal domain of GyrB, which contains the ATPase active site, but are not competitive inhibitors of the ATPase reaction. We propose that naphthoquinones bind to GyrB at a novel site close to the ATPase site. This novel mode of action could be exploited to develop new antibacterial agents.
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Affiliation(s)
- Shantanu Karkare
- Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
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29
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Ketron AC, Gordon ON, Schneider C, Osheroff N. Oxidative metabolites of curcumin poison human type II topoisomerases. Biochemistry 2012; 52:221-7. [PMID: 23253398 DOI: 10.1021/bi3014455] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The polyphenol curcumin is the principal flavor and color component of the spice turmeric. Beyond its culinary uses, curcumin is believed to positively impact human health and displays antioxidant, anti-inflammatory, antibacterial, and chemopreventive properties. It also is in clinical trials as an anticancer agent. In aqueous solution at physiological pH, curcumin undergoes spontaneous autoxidation that is enhanced by oxidizing agents. The reaction proceeds through a series of quinone methide and other reactive intermediates to form a final dioxygenated bicyclopentadione product. Several naturally occurring polyphenols that can form quinones have been shown to act as topoisomerase II poisons (i.e., they increase levels of topoisomerase II-mediated DNA cleavage). Because several of these compounds have chemopreventive properties, we determined the effects of curcumin, its oxidative metabolites, and structurally related degradation products (vanillin, ferulic acid, and feruloylmethane) on the DNA cleavage activities of human topoisomerase IIα and IIβ. Intermediates in the curcumin oxidation pathway increased the level of DNA scission mediated by both enzymes ~4-5-fold. In contrast, curcumin and the bicyclopentadione, as well as vanillin, ferulic acid, and feruloylmethane, had no effect on DNA cleavage. As found for other quinone-based compounds, curcumin oxidation intermediates acted as redox-dependent (as opposed to interfacial) topoisomerase II poisons. Finally, under conditions that promote oxidation, the dietary spice turmeric enhanced topoisomerase II-mediated DNA cleavage. Thus, even within the more complex spice formulation, oxidized curcumin intermediates appear to function as topoisomerase II poisons.
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Affiliation(s)
- Adam C Ketron
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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Lin TY, Huang CP, Au LC, Chang YW, Hu CY, Lin SB. A cysteine-reactive alkyl hydroquinone modifies topoisomerase IIα, enhances DNA breakage, and induces apoptosis in cancer cells. Chem Res Toxicol 2012; 25:2340-51. [PMID: 23088786 DOI: 10.1021/tx3002302] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We previously reported that the anticancer activity of a botanical compound 10'(Z),13'(E),15'(E)-heptadecatrienylhydroquinone [HQ17(3)] was attributed to topoisomerase (Topo) IIα poisoning and the induction of oxidative damage. HQ17(3) irreversibly inhibits Topo IIα activity in vitro and is more cytotoxic in leukemia HL-60 cells than in Topo IIα-deficient variant HL-60/MX2 cells, which suggests that Topo IIα is a cellular target of HQ17(3). This study further characterizes the molecular mechanisms of the anticancer activity of HQ17(3). Proteomic analyses indicated that HQ17(3) reacted with Cys-427, Cys-733, and Cys-997 of recombinant Topo IIα in vitro, whereas it reacted with Cys-427 of cellular Topo IIα in Huh7 hepatoma cells. The modification of HQ17(3) inhibited Topo IIα catalytic activity, increased the Topo IIα-DNA cleavage complex, and caused the accumulation of DNA breakage. In Huh7 cells, HQ17(3) treatment caused prompt inhibition of DNA synthesis and consequently induced the expression of DNA damage-related genes DDIT3, GADD45A, and GADD45G. Topo IIα inhibition, apoptosis, and oxidative stress were found to account for cytotoxicity caused by HQ17(3). Pretreatment of Huh7 cells with N-acetylcysteine (NAC) partially attenuated mitochondrial membrane damage, DNA breakage, and caspase activation. However, NAC pretreatment did not diminish HQ17(3)-induced cell death. These results suggest that the anticancer activity of HQ17(3) is attributed significantly to Topo IIα poisoning. The structural feature of HQ17(3) can be used as a model for the design of Topo IIα inhibitors and anticancer drugs.
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Affiliation(s)
- Ting-Yu Lin
- Department of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University, Taipei, Taiwan, Republic of China
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Benes P, Alexova P, Knopfova L, Spanova A, Smarda J. Redox state alters anti-cancer effects of wedelolactone. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2012; 53:515-524. [PMID: 22733624 DOI: 10.1002/em.21712] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Accepted: 05/23/2012] [Indexed: 06/01/2023]
Abstract
Wedelolactone is one of the active plant polyphenolic compounds. Anti-tumor effects of this drug have been demonstrated recently. We have described that wedelolactone acts as catalytic inhibitor of DNA topoisomerase IIα. The aim of this study was to further characterize the mechanism of its anti-tumor effects. We showed that wedelolactone inhibits binding of DNA topoisomerase IIα to plasmid DNA and antagonizes formation of etoposide-induced DNA cleavage complex. The inhibition of topoisomerase IIα by wedelolactone is reversible by excess of the enzyme but not DNA. The in vitro inhibitory effect of wedelolactone on the topoisomerase IIα activity is redox-dependent as it diminished in the presence of reducing agents. Cytotoxicity of wedelolactone was partially inhibited by N-acetylcysteine and glutathione ethyl ester in breast cancer MDA-MB-231 and MDA-MB-468 cells while the inhibitory effect of catalase was observed only in the former cell line. Finally, we found that wedelolactone can be oxidized in the presence of copper ions resulting in DNA strand break and abasic site formation in vitro. However, wedelolactone induced neither DNA damage in MDA-MB-231 cells nor mutations in bacterial cells detectable by Ames test suggesting that wedelolactone may not be an effective inducer of DNA damage. We conclude that the topoisomerase IIα inhibitory- and DNA damaging activities of wedelolactone in vitro depend on its redox state. Pro-oxidant activity could, however, explain only part of wedelolactone-induced cytotoxicity. Therefore, the major cellular target(s) of wedelolactone and the exact mechanism of wedelolactone-induced cytotoxicity still remain to be identified.
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Affiliation(s)
- Petr Benes
- Department of Experimental Biology, Masaryk University, Czech Republic.
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Chen YT, Collins TRL, Guan Z, Chen VB, Hsieh TS. Probing conformational changes in human DNA topoisomerase IIα by pulsed alkylation mass spectrometry. J Biol Chem 2012; 287:25660-8. [PMID: 22679013 DOI: 10.1074/jbc.m112.377606] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Type II topoisomerases are essential enzymes for solving DNA topological problems by passing one segment of DNA duplex through a transient double-strand break in a second segment. The reaction requires the enzyme to precisely control DNA cleavage and gate opening coupled with ATP hydrolysis. Using pulsed alkylation mass spectrometry, we were able to monitor the solvent accessibilities around 13 cysteines distributed throughout human topoisomerase IIα by measuring the thiol reactivities with monobromobimane. Most of the measured reactivities are in accordance with the predicted ones based on a homology structural model generated from available crystal structures. However, these results reveal new information for both the residues not covered in the structural model and potential differences between the modeled and solution holoenzyme structures. Furthermore, on the basis of the reactivity changes of several cysteines located at the N-gate and DNA gate, we could monitor the movement of topoisomerase II in the presence of cofactors and detect differences in the DNA gate between two closed clamp enzyme conformations locked by either 5'-adenylyl β,γ-imidodiphosphate or the anticancer drug ICRF-193.
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Affiliation(s)
- Yu-Tsung Chen
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA
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Ambati J, Song Y, Rankin SE, Lehmler HJ. Density Functional Theory Study of Semiquinone Radical Anions of Polychlorinated Biphenyls in the Syn- and Anti-like Conformation. J Phys Chem A 2012; 116:1586-95. [DOI: 10.1021/jp2077193] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Jyothirmai Ambati
- Department
of Chemical and Materials
Engineering, University of Kentucky, Lexington,
Kentucky 40506-0046, United States
| | - Yang Song
- College of Pharmaceutical Sciences, Southwest University, Chong Qing, 400716, P.R. China
- Department of Occupational and
Environmental Health, The University of Iowa, UI Research Park, Iowa City, Iowa 52242-5000, United States
| | - Stephen E. Rankin
- Department
of Chemical and Materials
Engineering, University of Kentucky, Lexington,
Kentucky 40506-0046, United States
| | - Hans-Joachim Lehmler
- Department of Occupational and
Environmental Health, The University of Iowa, UI Research Park, Iowa City, Iowa 52242-5000, United States
- Interdisciplinary Graduate Program
in Human Toxicology, The University of Iowa, Iowa City, Iowa 52242-5000, United States
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Ketron AC, Denny WA, Graves DE, Osheroff N. Amsacrine as a topoisomerase II poison: importance of drug-DNA interactions. Biochemistry 2012; 51:1730-9. [PMID: 22304499 DOI: 10.1021/bi201159b] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Amsacrine (m-AMSA) is an anticancer agent that displays activity against refractory acute leukemias as well as Hodgkin's and non-Hodgkin's lymphomas. The drug is comprised of an intercalative acridine moiety coupled to a 4'-amino-methanesulfon-m-anisidide headgroup. m-AMSA is historically significant in that it was the first drug demonstrated to function as a topoisomerase II poison. Although m-AMSA was designed as a DNA binding agent, the ability to intercalate does not appear to be the sole determinant of drug activity. Therefore, to more fully analyze structure-function relationships and the role of DNA binding in the action of m-AMSA, we analyzed a series of derivatives for the ability to enhance DNA cleavage mediated by human topoisomerase IIα and topoisomerase IIβ and to intercalate DNA. Results indicate that the 3'-methoxy (m-AMSA) positively affects drug function, potentially by restricting the rotation of the headgroup in a favorable orientation. Shifting the methoxy to the 2'-position (o-AMSA), which abrogates drug function, appears to increase the degree of rotational freedom of the headgroup and may impair interactions of the 1'-substituent or other portions of the headgroup within the ternary complex. Finally, the nonintercalative m-AMSA headgroup enhanced enzyme-mediated DNA cleavage when it was detached from the acridine moiety, albeit with 100-fold lower affinity. Taken together, our results suggest that much of the activity and specificity of m-AMSA as a topoisomerase II poison is embodied in the headgroup, while DNA intercalation is used primarily to increase the affinity of m-AMSA for the topoisomerase II-DNA cleavage complex.
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Affiliation(s)
- Adam C Ketron
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, United States
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Gurbani D, Kukshal V, Laubenthal J, Kumar A, Pandey A, Tripathi S, Arora A, Jain SK, Ramachandran R, Anderson D, Dhawan A. Mechanism of inhibition of the ATPase domain of human topoisomerase IIα by 1,4-benzoquinone, 1,2-naphthoquinone, 1,4-naphthoquinone, and 9,10-phenanthroquinone. Toxicol Sci 2012; 126:372-90. [PMID: 22218491 DOI: 10.1093/toxsci/kfr345] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The inhibition of human topoisomerase IIα (Hu-TopoIIα), a major enzyme involved in maintaining DNA topology, repair, and chromosome condensation/decondensation results in loss of genomic integrity. In the present study, the inhibition of ATPase domain of Hu-TopoIIα as a possible mechanism of genotoxicity of 1,4-benzoquinone (BQ), hydroquinone (HQ), naphthoquinone (1,2-NQ and 1,4-NQ), and 9,10-phenanthroquinone (9,10-PQ) was investigated. In silico modeling predicted that 1,4-BQ, 1,2-NQ, 1,4-NQ, and 9,10-PQ could interact with Ser-148, Ser-149, Asn-150, and Asn-91 residues of the ATPase domain of Hu-TopoIIα. Biochemical inhibition assays with the purified ATPase domain of Hu-TopoIIα revealed that 1,4-BQ is the most potent inhibitor followed by 1,4-NQ > 1,2-NQ > 9,10-PQ > HQ. Ligand-binding studies using isothermal titration calorimetry revealed that 1,4-BQ, HQ, 1,4-NQ, 1,2-NQ, and 9,10-PQ enter into four sequentially binding site models inside the domain. 1,4-BQ exhibited the strongest binding, followed by 1,4-NQ > 1,2-NQ > 9,10-PQ > HQ, as revealed by their average K(d) values. The cellular fate of such inhibition was further evidenced by an increase in the number of Hu-TopoIIα-DNA cleavage complexes in the human lung epithelial cells (BEAS-2B) using trapped in agarose DNA immunostaining (TARDIS) assay, which utilizes antibody specific for Hu-TopoIIα. Furthermore, the increase in γ-H2A.X levels quantitated by flow cytometry and visualized by immunofluorescence microscopy illustrated that accumulation of DNA double-strand breaks inside the cells can be attributed to the inhibition of Hu-TopoIIα. These findings collectively suggest that 1,4-BQ, 1,2-NQ, 1,4-NQ, and 9,10-PQ inhibit the ATPase domain and potentially result in Hu-TopoIIα-mediated clastogenic and leukemogenic events.
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Affiliation(s)
- Deepak Gurbani
- Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research, Lucknow-226001, Uttar Pradesh, India
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Song Y, Ambati J, Parkin S, Rankin SE, Robertson LW, Lehmler HJ. Crystal structure and density functional theory studies of toxic quinone metabolites of polychlorinated biphenyls. CHEMOSPHERE 2011; 85:386-392. [PMID: 21824639 PMCID: PMC3206982 DOI: 10.1016/j.chemosphere.2011.07.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 06/29/2011] [Accepted: 07/06/2011] [Indexed: 05/31/2023]
Abstract
Lower chlorinated polychlorinated biphenyls (PCBs) are readily metabolized via hydroxylated metabolites to reactive PCB quinones. Although these PCB metabolites elicit biochemical changes by mechanisms involving cellular target molecules, such as the aryl hydrocarbon receptor, and toxicity by interacting with enzymes like topoisomerases, only few PCB quinones have been synthesized and their conformational properties investigated. Similar to the parent compounds, knowledge of the three-dimensional structure of PCB quinones may therefore be important to assess their fate and risk. To address this gap in our knowledge, the gas phase molecular structure of a series of PCB quinones was predicted using HF/3-21G, B3LYP/6-31G∗∗ and UB3LYP/6-311G∗∗ calculations and compared to the respective solid state structure. All three methods overestimated the Cl-C bond length, but otherwise provided a reasonable approximation of the solid state bond angles and bond lengths. Overall, the UB3LYP/6-311G∗∗ level of theory yielded the best approximation of the molecular structure of PCB quinones in the solid state. Chlorine addition at the ortho position of both rings was found to increase the dihedral angle of the resulting quinone compound, which may have important implications for their interaction with cellular targets and, thus, their toxicity.
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Affiliation(s)
- Yang Song
- Key Laboratory on Luminescence and Real-Time Analysis (Ministry of Education), College of Pharmaceutical Sciences, Southwest University, Chong Qing, 400716, P.R. China
- Department of Occupational and Environmental Health, The University of Iowa, 100 UI Research Park, 221 IREH, Iowa City, IA 52242-5000, USA
| | - Jyothirmai Ambati
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506-13 0046, USA
| | - Sean Parkin
- Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055, USA
| | - Stephen E. Rankin
- Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506-13 0046, USA
| | - Larry W. Robertson
- Department of Occupational and Environmental Health, The University of Iowa, 100 UI Research Park, 221 IREH, Iowa City, IA 52242-5000, USA
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, Iowa City, IA 52242-5000, USA
| | - Hans-Joachim Lehmler
- Department of Occupational and Environmental Health, The University of Iowa, 100 UI Research Park, 221 IREH, Iowa City, IA 52242-5000, USA
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, Iowa City, IA 52242-5000, USA
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Lin RK, Zhou N, Lyu YL, Tsai YC, Lu CH, Kerrigan J, Chen YT, Guan Z, Hsieh TS, Liu LF. Dietary isothiocyanate-induced apoptosis via thiol modification of DNA topoisomerase IIα. J Biol Chem 2011; 286:33591-600. [PMID: 21828038 DOI: 10.1074/jbc.m111.258137] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Studies in animal models have indicated that dietary isothiocyanates (ITCs) exhibit cancer preventive activities through carcinogen detoxification-dependent and -independent mechanisms. The carcinogen detoxification-independent mechanism of cancer prevention by ITCs has been attributed at least in part to their ability to induce apoptosis of transformed (initiated) cells (e.g. through suppression of IκB kinase and nuclear factor κB as well as other proposed mechanisms). In the current studies we show that ITC-induced apoptosis of oncogene-transformed cells involves thiol modification of DNA topoisomerase II (Top2) based on the following observations. 1) siRNA-mediated knockdown of Top2α in both SV40-transformed MEFs and Ras-transformed human mammary epithelial MCF-10A cells resulted in reduced ITC sensitivity. 2) ITCs, like some anticancer drugs and cancer-preventive dietary components, were shown to induce reversible Top2α cleavage complexes in vitro. 3) ITC-induced Top2α cleavage complexes were abolished by co-incubation with excess glutathione. In addition, proteomic analysis revealed that several cysteine residues on human Top2α were covalently modified by benzyl-ITC, suggesting that ITC-induced Top2α cleavage complexes may involve cysteine modification. Interestingly, consistent with the thiol modification mechanism for Top2α cleavage complex induction, the thiol-reactive selenocysteine, but not the non-thiol-reactive selenomethionine, was shown to induce Top2α cleavage complexes. In the aggregate, our results suggest that thiol modification of Top2α may contribute to apoptosis induction in transformed cells by ITCs.
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Affiliation(s)
- Ren-Kuo Lin
- Department of Pharmacology and the Cancer Institute of New Jersey, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Jersey 08854, USA
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39
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Jacob DA, Mercer SL, Osheroff N, Deweese JE. Etoposide quinone is a redox-dependent topoisomerase II poison. Biochemistry 2011; 50:5660-7. [PMID: 21595477 DOI: 10.1021/bi200438m] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Etoposide is a topoisomerase II poison that is used to treat a variety of human cancers. Unfortunately, 2-3% of patients treated with etoposide develop treatment-related leukemias characterized by 11q23 chromosomal rearrangements. The molecular basis for etoposide-induced leukemogenesis is not understood but is associated with enzyme-mediated DNA cleavage. Etoposide is metabolized by CYP3A4 to etoposide catechol, which can be further oxidized to etoposide quinone. A CYP3A4 variant is associated with a lower risk of etoposide-related leukemias, suggesting that etoposide metabolites may be involved in leukemogenesis. Although etoposide acts at the enzyme-DNA interface, several quinones poison topoisomerase II via redox-dependent protein adduction. The effects of etoposide quinone on topoisomerase IIα-mediated DNA cleavage have been examined previously. Although findings suggest that the activity of the quinone is slightly greater than that of etoposide, these studies were carried out in the presence of significant levels of reducing agents (which should reduce etoposide quinone to the catechol). Therefore, we examined the ability of etoposide quinone to poison human topoisomerase IIα in the absence of reducing agents. Under these conditions, etoposide quinone was ∼5-fold more active than etoposide at inducing enzyme-mediated DNA cleavage. Consistent with other redox-dependent poisons, etoposide quinone inactivated topoisomerase IIα when incubated with the protein prior to DNA and lost activity in the presence of dithiothreitol. Unlike etoposide, the quinone metabolite did not require ATP for maximal activity and induced a high ratio of double-stranded DNA breaks. Our results support the hypothesis that etoposide quinone contributes to etoposide-related leukemogenesis.
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Affiliation(s)
- David A Jacob
- Department of Pharmaceutical Sciences, Lipscomb University College of Pharmacy, Nashville, Tennessee 37204-3951, USA
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Mondrala S, Eastmond DA. Topoisomerase II inhibition by the bioactivated benzene metabolite hydroquinone involves multiple mechanisms. Chem Biol Interact 2010; 184:259-68. [DOI: 10.1016/j.cbi.2009.12.023] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2009] [Revised: 12/07/2009] [Accepted: 12/15/2009] [Indexed: 11/26/2022]
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41
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Pyranonaphthoquinone derivatives of eleutherin, ventiloquinone L, thysanone and nanaomycin A possessing a diverse topoisomerase II inhibition and cytotoxicity spectrum. Bioorg Med Chem 2009; 17:7131-7. [DOI: 10.1016/j.bmc.2009.08.064] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2009] [Revised: 08/20/2009] [Accepted: 08/29/2009] [Indexed: 11/24/2022]
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42
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Bakunina IY, Kol′tsova EA, Pokhilo ND, Shestak OP, Yakubovskaya AY, Zvyagintseva TN, Anufriev VF. Effect of 5-hydroxy- and 5,8-dihydroxy-1,4-naphthoquinones on the hydrolytic activity of α-galactosidase. Chem Nat Compd 2009. [DOI: 10.1007/s10600-009-9252-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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43
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Deweese JE, Osheroff N. The DNA cleavage reaction of topoisomerase II: wolf in sheep's clothing. Nucleic Acids Res 2008; 37:738-48. [PMID: 19042970 PMCID: PMC2647315 DOI: 10.1093/nar/gkn937] [Citation(s) in RCA: 332] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Topoisomerase II is an essential enzyme that is required for virtually every process that requires movement of DNA within the nucleus or the opening of the double helix. This enzyme helps to regulate DNA under- and overwinding and removes knots and tangles from the genetic material. In order to carry out its critical physiological functions, topoisomerase II generates transient double-stranded breaks in DNA. Consequently, while necessary for cell survival, the enzyme also has the capacity to fragment the genome. The DNA cleavage/ligation reaction of topoisomerase II is the target for some of the most successful anticancer drugs currently in clinical use. However, this same reaction also is believed to trigger chromosomal translocations that are associated with specific types of leukemia. This article will familiarize the reader with the DNA cleavage/ligation reaction of topoisomerase II and other aspects of its catalytic cycle. In addition, it will discuss the interaction of the enzyme with anticancer drugs and the mechanisms by which these agents increase levels of topoisomerase II-generated DNA strand breaks. Finally, it will describe dietary and environmental agents that enhance DNA cleavage mediated by the enzyme.
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Affiliation(s)
- Joseph E Deweese
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146 USA
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44
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Bandele OJ, Clawson SJ, Osheroff N. Dietary polyphenols as topoisomerase II poisons: B ring and C ring substituents determine the mechanism of enzyme-mediated DNA cleavage enhancement. Chem Res Toxicol 2008; 21:1253-60. [PMID: 18461976 DOI: 10.1021/tx8000785] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Dietary polyphenols are a diverse and complex group of compounds that are linked to human health. Many of their effects have been attributed to the ability to poison (i.e., enhance DNA cleavage by) topoisomerase II. Polyphenols act against the enzyme by at least two different mechanisms. Some compounds are traditional, redox-independent topoisomerase II poisons, interacting with the enzyme in a noncovalent manner. Conversely, others enhance DNA cleavage in a redox-dependent manner that requires covalent adduction to topoisomerase II. Unfortunately, the structural elements that dictate the mechanism by which polyphenols poison topoisomerase II have not been identified. To resolve this issue, the activities of two classes of polyphenols against human topoisomerase IIalpha were examined. The first class was a catechin series, including (-)-epigallocatechin gallate (EGCG), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and (-)-epicatechin (EC). The second was a flavonol series, including myricetin, quercetin, and kaempferol. Compounds were categorized into four distinct groups: EGCG and EGC were redox-dependent topoisomerase II poisons, kaempferol and quercetin were traditional poisons, myricetin utilized both mechanisms, and ECG and EC displayed no significant activity. On the basis of these findings, a set of rules is proposed that predicts the mechanism of bioflavonoid action against topoisomerase II. The first rule centers on the B ring. While the C4'-OH is critical for the compound to act as a traditional poison, the addition of -OH groups at C3' and C5' increases the redox activity of the B ring and allows the compound to act as a redox-dependent poison. The second rule centers on the C ring. The structure of the C ring in the flavonols is aromatic and planar and includes a C4-keto group that allows the formation of a proposed pseudo ring with the C5-OH. Disruption of these elements abrogates enzyme binding and precludes the ability to function as a traditional topoisomerase II poison.
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Affiliation(s)
- Omari J Bandele
- Department of Biochemistry, Vanderbilt UniVersity School of Medicine, Nashville, Tennessee 37232-0146, USA
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45
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Jacobus J, Flor S, Klingelhutz A, Robertson L, Ludewig G. 2-(4'-CHLOROPHENYL)-1,4-BENZOQUINONE INCREASES THE FREQUENCY OF MICRONUCLEI AND SHORTENS TELOMERES. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2008; 25:267-272. [PMID: 18438462 PMCID: PMC2346440 DOI: 10.1016/j.etap.2007.10.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The toxicity of polychlorinated biphenyls (PCBs) has been attributed widely to receptor-mediated effects, buttressed by the popularity of the Toxic Equivalency Factor. We propose that a crucial toxic mechanism of lower-chlorinated PCBs is their enzymatic biotransformation to electrophiles, including quinoid metabolites, that bind intracellular sulfhydryl groups, such as those found in microtubulin and enzymes like telomerase. To test this hypothesis, we have examined micronuclei induction, cell cycle, and telomere shortening in cells in culture. Our findings show a large increase in micronuclei frequency and cell cycle perturbation in V79 cells, and a marked decrease in telomere length in HaCaT cells exposed to 2-(4'-chlorophenyl)-1,4-benzoquinone (PCB3pQ).
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Affiliation(s)
- J.A. Jacobus
- Department of Occupational and Environmental Health, University of Iowa, 100 Oakdale Campus # 124 IREH, Iowa City, IA 52242-5000
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa
| | - S. Flor
- Department of Occupational and Environmental Health, University of Iowa, 100 Oakdale Campus # 124 IREH, Iowa City, IA 52242-5000
| | | | - L.W. Robertson
- Department of Occupational and Environmental Health, University of Iowa, 100 Oakdale Campus # 124 IREH, Iowa City, IA 52242-5000
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa
| | - G. Ludewig
- Department of Occupational and Environmental Health, University of Iowa, 100 Oakdale Campus # 124 IREH, Iowa City, IA 52242-5000
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa
- Address all correspondence to: Dr. Gabriele Ludewig, Department of Occupational & Environmental Health, College of Public Health, University of Iowa, 100 Oakdale Campus, #234 IREH, Iowa City, IA 52242-5000, Phone: 319/335-4650, Fax: 319/335-4290, e-mail:
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46
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Ludewig G, Lehmann L, Esch H, Robertson LW. Metabolic Activation of PCBs to Carcinogens in Vivo - A Review. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2008; 25:241-6. [PMID: 18452002 PMCID: PMC2364599 DOI: 10.1016/j.etap.2007.10.029] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Many higher-chlorinated biphenyls, persistent and predominant in foods, are active as promoters in hepatocarcinogenesis. Lower-chlorinated biphenyls, predominating in indoor and outdoor air, are more readily metabolized and therefore shorter lived, 'episodic' contaminants. Thus inhalation of such lower chlorinated biphenyls may expose humans to reactive, possibly genotoxic/carcinogenic intermediates. Lower chlorinated biphenyls may be metabolized via arene-oxides to mono- and dihydroxylated intermediates and further to (semi)quinones, highly reactive intermediates. Covalently bound lower chlorinated biphenyls have been detected in rodent tissues in vivo. We recently showed using the modified Solt-Farber foci assay that several mono- to tetrachlorinated biphenyls have initiating activity in the livers of rats. In a follow-up study of PCB3 (4-chlorobiphenyl) metabolites only one monohydroxy- and one quinoid- metabolite showed initiating activity, indicating that the metabolic activation of PCB3 proceeds via hydroxylation and oxidation to the 3,4-quinone, the ultimate carcinogen. Since cancer initiation is based on genotoxic event(s), we hypothesized that PCB3 and/or its metabolite(s) are mutagenic in rat liver in vivo. To investigate this, BigBlue® rats, transgenic for the lacI reporter gene, were exposed to PCB3 and 4-hydroxy-PCB3 (4-HO-PCB3). In male rats the mutant frequency (MF) of lac I in the liver was significantly elevated and the mutation spectrum differed significantly from the control. 4-HO-PCB3 caused a non-significant (p = 0.115) doubling of the MF compared to the control. These studies prove that lower halogenated biphenyls may be metabolically activated in vivo to genotoxic and initiating intermediates.
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Affiliation(s)
- Gabriele Ludewig
- Department of Occupational & Environmental Health, College of Public Health, University of Iowa, Iowa City, IA 52242, USA
- Address all correspondence to: Dr. Gabriele Ludewig, Department of Occupational & Environmental Health, College of Public Health, University of Iowa, 100 Oakdale Campus, #234 IREH, Iowa City, IA 52242-5000, Phone: 319/335-4650, Fax: 319/335-4290, e-mail:
| | | | | | - Larry W. Robertson
- Department of Occupational & Environmental Health, College of Public Health, University of Iowa, Iowa City, IA 52242, USA
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47
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Bandele OJ, Osheroff N. (-)-Epigallocatechin gallate, a major constituent of green tea, poisons human type II topoisomerases. Chem Res Toxicol 2008; 21:936-43. [PMID: 18293940 DOI: 10.1021/tx700434v] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
(-)-Epigallocatechin gallate (EGCG) is the most abundant and biologically active polyphenol in green tea, and many of the therapeutic benefits of the beverage have been attributed to this compound. High concentrations of EGCG are cytotoxic and trigger genotoxic events in mammalian cells. Although this catechin affects a number of cellular systems, the genotoxic effects of several bioflavonoid-based dietary polyphenols are believed to be mediated, at least in part, by their actions on topoisomerase II. Therefore, the effects of green tea extract and EGCG on DNA cleavage mediated by human topoisomerase IIalpha and beta were characterized. The extract and EGCG increased levels of DNA strand breaks generated by both enzyme isoforms. However, EGCG acted by a mechanism that was distinctly different from those of genistein, a dietary polyphenol, and etoposide, a widely prescribed anticancer drug. In contrast to these agents, EGCG exhibited all of the characteristics of a redox-dependent topoisomerase II poison that acts by covalently adducting to the enzyme. First, EGCG stimulated DNA scission mediated by both isoforms primarily at sites that were cleaved in the absence of compounds. Second, exposure of EGCG to the reducing agent dithiothreitol (DTT) prior to its addition to DNA cleavage assays abrogated the effects of the catechin on DNA scission. Third, once EGCG stimulated topoisomerase II-mediated DNA cleavage, exposure to DTT did not effect levels of DNA strand breaks. Finally, EGCG inhibited the DNA cleavage activities of topoisomerase IIalpha and beta when incubated with either enzyme prior to the addition of DNA. Taken together, these results provide strong evidence that EGCG is a redox-dependent topoisomerase II poison and utilizes a mechanism similar to that of 1,4-benzoquinone.
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Affiliation(s)
- Omari J Bandele
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146, USA
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Peters M, Kogan NM. HU-331: a cannabinoid quinone, with uncommon cytotoxic properties and low toxicity. Expert Opin Investig Drugs 2007; 16:1405-13. [PMID: 17714026 DOI: 10.1517/13543784.16.9.1405] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The oxidation of cannabis constituents has given rise to their corresponding quinones, which have been identified as cytotoxic agents. Out of these molecules the quinone of cannabidiol--the most abundant non-psychoactive cannabinoid in Cannabis sativa--has shown the highest cytotoxicity. This compound was named HU-331 and it exerts antiangiogenic properties, induces apoptosis to endothelial cells and inhibits topoisomerase II in nanomolar concentrations. Unlike other quinones, it is not cardiotoxic and does not induce the formation of free radicals. A comparative in vivo study in mice has shown HU-331 to be less toxic and more effective than the commonly used doxorubicin. This review summarises the properties of HU-331 and compares it with doxorubicin and other topoisomerase II inhibitors.
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Affiliation(s)
- Maximilian Peters
- The Hebrew University, Department of Medicinal Chemistry and Natural Products, School of Pharmacy, Jerusalem, Israel
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49
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Bender RP, Osheroff N. Mutation of cysteine residue 455 to alanine in human topoisomerase IIalpha confers hypersensitivity to quinones: enhancing DNA scission by closing the N-terminal protein gate. Chem Res Toxicol 2007; 20:975-81. [PMID: 17516663 PMCID: PMC2893044 DOI: 10.1021/tx700062t] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Several quinone-based metabolites of industrial and environmental toxins are potent topoisomerase II poisons. These compounds act by adducting the protein, and previous studies suggest that they increase levels of enzyme-associated DNA strand breaks by at least two potential mechanisms. Quinones act directly on the DNA cleavage-ligation equilibrium of topoisomerase II by inhibiting the rate of ligation. They also block the N-terminal gate of the protein, thereby stabilizing topoisomerase II in its "closed clamp" form and trapping DNA in the central annulus of the enzyme. It has been proposed that this latter activity enhances DNA cleavage by increasing the population of enzyme molecules with DNA in their active sites, but a causal relationship has not been established. In order to more fully characterize the mechanistic basis for quinone action against topoisomerase II, the present study characterized the sensitivity of human topoisomerase IIalpha carrying a Cys455-->Ala mutation (top2alphaC455A) toward quinones. Cys455 was identified as a site of quinone adduction by mass spectrometry. The mutant enzyme was approximately 1.5-2-fold hypersensitive to 1,4-benzoquinone and the polychlorinated biphenyl quinone 4'Cl-2,5pQ, but it displayed wild-type sensitivity to traditional topoisomerase II poisons. The ability of 1,4-benzoquinone to inhibit DNA ligation mediated by top2alphaC455A was similar to that of wild-type topoisomerase IIalpha. However, the quinone induced approximately 3 times the level of clamp closure with the mutant enzyme. These findings strongly support the hypothesis that the ability of quinones to block the N-terminal gate of the type II enzyme contributes to their actions as topoisomerase II poisons.
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MESH Headings
- Alanine/chemistry
- Alanine/genetics
- Alanine/metabolism
- Amino Acid Substitution
- Antigens, Neoplasm/chemistry
- Antigens, Neoplasm/genetics
- Antigens, Neoplasm/metabolism
- Benzoquinones/chemistry
- Benzoquinones/pharmacology
- Cysteine/chemistry
- Cysteine/genetics
- Cysteine/metabolism
- DNA Cleavage/drug effects
- DNA Topoisomerases, Type II/chemistry
- DNA Topoisomerases, Type II/genetics
- DNA Topoisomerases, Type II/metabolism
- DNA, Superhelical/genetics
- DNA, Superhelical/metabolism
- DNA-Binding Proteins/chemistry
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- Etoposide/chemistry
- Etoposide/pharmacology
- Humans
- Kinetics
- Mass Spectrometry
- Models, Molecular
- Mutant Proteins/chemistry
- Mutant Proteins/metabolism
- Mutation
- Protein Structure, Tertiary
- Quinones/chemistry
- Quinones/pharmacology
- Recombinant Proteins/chemistry
- Recombinant Proteins/metabolism
- Temperature
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Affiliation(s)
| | - Neil Osheroff
- To whom correspondence should be addressed. Tel: 615-322-4338. Fax: 615-343-1166.
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