1
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Sharma P, Sweta Jha N. Enhanced antioxidant and cytotoxic activity of ferrocenyl-substituted curcumin via stabilization of promoter c-MYC silencer element. J Biomol Struct Dyn 2023; 41:9539-9550. [PMID: 36345790 DOI: 10.1080/07391102.2022.2143424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 10/29/2022] [Indexed: 11/11/2022]
Abstract
We are reporting a successful attachment of ferrocenyl moiety at the active methylene carbon atom of β-diketone of curcumin via Knoevenagel condensation reaction, to utilize the optimum selectivity toward biological targets. The formation of ferrocenyl curcumin (i.e., Fc-cur) has been confirmed by 1H NMR, 13C NMR, and FT-IR spectra analysis. Further, circular dichroism (CD) spectroscopy, thermal denaturation, absorption, and fluorescence spectroscopy have been used to understand the association of ligand (i.e., Fc-cur) with G-quadruplex. Based on these analysis, the binding mechanism of the ligand i.e., Fc-cur to the parallel and hybrid topology present in different G-quadruplex has been proposed. Further, the binding and modes of the interaction of Fc-cur with Pu27 c-MYC silencer element and H-telo G-quadruplex have unravelled selective and stronger binding via intercalation with the parallel topology of c-MYC G-quadruplex rather than the hybrid topology of H-telo quadruplex. The manifestation of better antioxidant activity of Fc-cur has been demonstrated by showing a stronger radical scavenging capability than pristine curcumin. The cytotoxicity analysis of the proposed ligand i.e., Fc-cur against Vero and HeLa cells have clearly reflected the nontoxicity toward Vero cells and quite effective against the HeLa cells which reduces the cancer cells more effectively than the already reported for curcumin.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Padma Sharma
- Department of Chemistry, National Institute of Technology, Patna, India
| | - Niki Sweta Jha
- Department of Chemistry, National Institute of Technology, Patna, India
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2
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Liu L, Geng X, Zhang J, Li S, Gao J. Structure-based discovery of Licoflavone B and Ginkgetin targeting c-Myc G-quadruplex to suppress c-Myc transcription and myeloma growth. Chem Biol Drug Des 2022; 100:525-533. [PMID: 35557489 DOI: 10.1111/cbdd.14064] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 05/04/2022] [Accepted: 05/08/2022] [Indexed: 11/27/2022]
Abstract
G-quadruplex (G4), present in the c-Myc promoter, has emerged as an attractive cancer-specific molecular target for drug development. So, the discovery of small molecules to stabilize c-Myc-G4 to inhibit transcription of c-Myc protein is of great significance. Herein, a combined molecular docking-based virtual screening strategy, molecular dynamics (MD) simulation, and molecular mechanics/generalized Born surface area (MM/GBSA) free energy calculation was conducted on the existing L6000 Natural Compound Library. Four natural compounds, including Licoflavone B, Demethyleneberberine, Ginkgetin, and Mulberroside C, were predicted to have preferable binding affinities to c-Myc G4 and then selected for commercial purchase and experimental evaluation. Compounds Licoflavone B and Ginkgetin can significantly inhibit myeloma cell proliferation, with IC50 values <8 μM against the RPMI-8226 cell line. Moreover, our data demonstrated that the two compounds could simultaneously downregulate c-Myc transcription and expression. Collectively, compounds Licoflavone B and Ginkgetin might be regarded as new candidates for the development of the more potent c-Myc-G4 stabilizers in the future.
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Affiliation(s)
- Linlin Liu
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, China.,College of Medical Imaging, Xuzhou Medical University, Xuzhou, China
| | - Xiaoju Geng
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, China
| | - Jinyuan Zhang
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, China
| | - Shihao Li
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, China
| | - Jian Gao
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, China
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3
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Zhang J, Wang T, Geng X, Liu L, Gao J. Identification of Trovafloxacin, Ozanimod, and Ozenoxacin as potent c-Myc G-quadruplex stabilizers to suppress c-Myc transcription and myeloma growth. Mol Inform 2022; 41:e2200011. [PMID: 35355429 DOI: 10.1002/minf.202200011] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Accepted: 03/31/2022] [Indexed: 11/06/2022]
Abstract
c-Myc is a major oncogene that is estimated to result in almost all human cancers and the c-Myc downregulation has become an attractive strategy for cancer treatment. For it is hard to design compounds that can directly interact with the c-Myc protein, the DNA G-quadruplex (G4) was discovered in its promoter region which was referred to as a potential drug target for controlling c-Myc expression. In this study, a combined strategy of molecular docking-based virtual screening, molecular dynamics (MD) simulation, and molecular mechanics/generalized Born surface area (MM/GBSA) free energy calculation was conducted on the existing FDA-Approved Drugs Library, eight compounds were selected for further experimental assay. Among them, five compounds exhibited dose-dependently anticancer activities against RPMI-8226 cells with IC50 values less than 18.4 μM. Further experiments showed that Trovafloxacin, Ozanimod, and Ozenoxacin decreased c-Myc mRNA level obviously and downregulated c-Myc expression significantly. In summary, compounds Trovafloxacin, Ozanimod, and Ozenoxacin might be regarded as new c-Myc G4 stabilizers for the treatment of c-Myc related cancers in the future.
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Affiliation(s)
| | - Tao Wang
- Xuzhou Medical University, CHINA
| | | | | | - Jian Gao
- Xuzhou Medical University, CHINA
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4
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Pandya N, Bhagwat SR, Kumar A. Regulatory role of Non-canonical DNA Polymorphisms in human genome and their relevance in Cancer. Biochim Biophys Acta Rev Cancer 2021; 1876:188594. [PMID: 34303788 DOI: 10.1016/j.bbcan.2021.188594] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Revised: 07/19/2021] [Accepted: 07/19/2021] [Indexed: 12/17/2022]
Abstract
DNA has the ability to form polymorphic structures like canonical duplex DNA and non-canonical triplex DNA, Cruciform, Z-DNA, G-quadruplex (G4), i-motifs, and hairpin structures. The alteration in the form of DNA polymorphism in the response to environmental changes influences the gene expression. Non-canonical structures are engaged in various biological functions, including chromatin epigenetic and gene expression regulation via transcription and translation, as well as DNA repair and recombination. The presence of non-canonical structures in the regulatory region of the gene alters the gene expression and affects the cellular machinery. Formation of non-canonical structure in the regulatory site of cancer-related genes either inhibits or dysregulate the gene function and promote tumour formation. In the current article, we review the influence of non-canonical structure on the regulatory mechanisms in human genome. Moreover, we have also discussed the relevance of non-canonical structures in cancer and provided information on the drugs used for their treatment by targeting these structures.
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Affiliation(s)
- Nirali Pandya
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Simrol, Indore 453552, India
| | - Sonali R Bhagwat
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Simrol, Indore 453552, India
| | - Amit Kumar
- Department of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Simrol, Indore 453552, India.
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5
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G-quadruplex stabilization via small-molecules as a potential anti-cancer strategy. Biomed Pharmacother 2021; 139:111550. [PMID: 33831835 DOI: 10.1016/j.biopha.2021.111550] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 03/24/2021] [Accepted: 03/24/2021] [Indexed: 12/16/2022] Open
Abstract
G-quadruplexes (G4) are secondary four-stranded DNA helical structures consisting of guanine-rich nucleic acids, which can be formed in the promoter regions of several genes under proper conditions. Several cancer cells have been shown to emerge from genomic changes in the expression of crucial growth-regulating genes that allow cells to develop and begin to propagate in an undifferentiated state. Recent attempts have focused on producing treatments targeted at particular protein products of genes that are abnormally expressed. Many of the proteins found are hard to target and considered undruggable due to structural challenges, protein overexpression, or mutations that affect treatment resistance. The utilization of small molecules that stabilize secondary DNA structures existing in several possible oncogenes' promoters and modulate their transcription is a new strategy that avoids some of these problems. In this review, we outline the function of G-quadruplex stabilization in cancer by small-molecules with the aim to improve cancer therapy.
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6
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Amjadi-Moheb F, Paniri A, Akhavan-Niaki H. Insights into the Links between MYC and 3D Chromatin Structure and Epigenetics Regulation: Implications for Cancer Therapy. Cancer Res 2021; 81:1925-1936. [PMID: 33472888 DOI: 10.1158/0008-5472.can-20-3613] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 12/21/2020] [Accepted: 01/06/2021] [Indexed: 11/16/2022]
Abstract
MYC is embedded in the transcriptional oasis of the 8q24 gene desert. A plethora of genomic elements has roles in MYC aberrant expression in cancer development by interacting with transcription factors and epigenetics regulators as well as altering the structure of chromatin at the MYC locus and tissue-specific long-range enhancer-promoter contacts. Furthermore, MYC is a master regulator of several human cancers by modulating the transcription of numerous cancer-related genes through epigenetic mechanisms. This review provides a comprehensive overview of the three-dimensional genomic organization around MYC and the role of epigenetic machinery in transcription and function of MYC as well as discusses various epigenetic-targeted therapeutic strategies in MYC-driven cancers.
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Affiliation(s)
- Fatemeh Amjadi-Moheb
- Department of Genetics, Faculty of Medicine, Babol University of Medical Sciences, Babol, Iran
| | - Alireza Paniri
- Department of Genetics, Faculty of Medicine, Babol University of Medical Sciences, Babol, Iran
| | - Haleh Akhavan-Niaki
- Department of Genetics, Faculty of Medicine, Babol University of Medical Sciences, Babol, Iran.
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7
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Chaudhuri R, Bhattacharya S, Dash J, Bhattacharya S. Recent Update on Targeting c-MYC G-Quadruplexes by Small Molecules for Anticancer Therapeutics. J Med Chem 2020; 64:42-70. [PMID: 33355454 DOI: 10.1021/acs.jmedchem.0c01145] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Guanine-rich DNA sequences have the propensity to adopt four-stranded tetrahelical G-quadruplex (G4) structures that are overrepresented in gene promoters. The structural polymorphism and physicochemical properties of these non-Watson-Crick G4 structures make them important targets for drug development. The guanine-rich nuclease hypersensitivity element III1 present in the upstream of P1 promoter of c-MYC oncogene has the ability to form an intramolecular parallel G4 structure. The G4 structure that forms transiently in the c-MYC promoter functions as a transcriptional repressor element. The c-MYC oncogene is overexpressed in a wide variety of cancers and plays a key role in cancer progression. Till now, a large number of compounds that are capable of interacting and stabilizing thec-MYC G4 have been reported. In this review, we summarize various c-MYC G4 specific molecules and discuss their effects on c-MYC gene expression in vitro and in vivo.
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Affiliation(s)
- Ritapa Chaudhuri
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
| | - Semantee Bhattacharya
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
| | - Jyotirmayee Dash
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
| | - Santanu Bhattacharya
- School of Applied & Interdisciplinary Sciences, Indian Association for the Cultivation of Science, Kolkata 700032, India.,Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012, India
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8
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Jana J, Weisz K. A Thermodynamic Perspective on Potential G-Quadruplex Structures as Silencer Elements in the MYC Promoter. Chemistry 2020; 26:17242-17251. [PMID: 32761687 PMCID: PMC7839732 DOI: 10.1002/chem.202002985] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 07/31/2020] [Indexed: 01/10/2023]
Abstract
Multiple G‐tracts within the promoter region of the c‐myc oncogene may fold into various G‐quadruplexes with the recruitment of different tracts and guanosine residues for the G‐core assembly. Thermodynamic profiles for the folding of wild‐type and representative truncated as well as mutated sequences were extracted by comprehensive DSC experiments. The unique G‐quadruplex involving consecutive G‐tracts II–V with formation of two one‐nucleotide and one central two‐nucleotide propeller loop, previously proposed to be the biologically most relevant species, was found to be the most stable fold in terms of its Gibbs free energy of formation at ambient temperatures. Its stability derives from its short propeller loops but also from the favorable type of loop residues. Whereas quadruplex folds with long propeller loops are significantly disfavored, a snap‐back loop structure formed by incorporating a 3’‐terminal guanosine into the empty position of a tetrad seems highly competitive based on its thermodynamic stability. However, its destabilization by extending the 3’‐terminus questions the significance of such a species under in vivo conditions.
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Affiliation(s)
- Jagannath Jana
- Institute of Biochemistry, Universität Greifswald, Felix-Hausdorff-Str. 4, 17487, Greifswald, Germany
| | - Klaus Weisz
- Institute of Biochemistry, Universität Greifswald, Felix-Hausdorff-Str. 4, 17487, Greifswald, Germany
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9
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Pandya N, Khan E, Jain N, Satham L, Singh R, Makde RD, Mishra A, Kumar A. Curcumin analogs exhibit anti-cancer activity by selectively targeting G-quadruplex forming c-myc promoter sequence. Biochimie 2020; 180:205-221. [PMID: 33188859 DOI: 10.1016/j.biochi.2020.11.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 10/10/2020] [Accepted: 11/03/2020] [Indexed: 12/30/2022]
Abstract
Curcumin exhibits a broad spectrum of beneficial health properties that include anti-tumor and anti-cancer activities. The down-regulation of c-myc transcription via stabilizing the G-quadruplex structure formed at the promoter region of the human c-myc gene allows the repression in cancer growth. Small molecules can bind and stabilize this structure to provide an exciting and promising strategy for anti-cancer therapeutics. Herein, we investigated the interaction of Curcumin and its synthetic analogs with G-quadruplex DNA formed at the c-myc promoter by using various biophysical and biochemical assays. Further, its cytotoxic effect and mechanistic insights were explored in various cancer cell lines as well as in multicellular tumor spheroid (MCTS) model. The MCTS possesses almost similar microenvironment as avascular tumors, and micro-metastases can be used as a suitable model for the small molecule-based therapeutics development. Our study provides an expanded overview of the anti-cancer effect of a new Curcumin analog via targeting G-quadruplex structures formed at the promoter region of the human c-myc gene.
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Affiliation(s)
- Nirali Pandya
- Discipline of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Simrol, Indore, 453552, India
| | - Eshan Khan
- Discipline of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Simrol, Indore, 453552, India
| | - Neha Jain
- Discipline of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Simrol, Indore, 453552, India
| | - Lakshminarayana Satham
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, 400076, Maharashtra, India
| | - Rahul Singh
- High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Mumbai, 400085, India
| | - Ravindra D Makde
- High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Mumbai, 400085, India
| | - Amit Mishra
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Rajasthan, 342011, India
| | - Amit Kumar
- Discipline of Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Simrol, Indore, 453552, India.
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10
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Human MYC G-quadruplex: From discovery to a cancer therapeutic target. Biochim Biophys Acta Rev Cancer 2020; 1874:188410. [PMID: 32827579 DOI: 10.1016/j.bbcan.2020.188410] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 07/21/2020] [Accepted: 07/21/2020] [Indexed: 02/06/2023]
Abstract
Overexpression of the MYC oncogene is a molecular hallmark of both cancer initiation and progression. Targeting MYC is a logical and effective cancer therapeutic strategy. A special DNA secondary structure, the G-quadruplex (G4), is formed within the nuclease hypersensitivity element III1 (NHE III1) region, located upstream of the MYC gene's P1 promoter that drives the majority of its transcription. Targeting such G4 structures has been a focus of anticancer therapies in recent decades. Thus, a comprehensive review of the MYC G4 structure and its role as a potential therapeutic target is timely. In this review, we first outline the discovery of the MYC G4 structure and evidence of its formation in vitro and in cells. Then, we describe the functional role of G4 in regulating MYC gene expression. We also summarize three types of MYC G4-interacting proteins that can promote, stabilize and unwind G4 structures. Finally, we discuss G4-binding molecules and the anticancer activities of G4-stabilizing ligands, including small molecular compounds and peptides, and assess their potential as novel anticancer therapeutics.
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11
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Rauser V, Weinhold E. Quantitative Formation of Monomeric G-Quadruplex DNA from Multimeric Structures of c-Myc Promoter Sequence. Chembiochem 2020; 21:2445-2448. [PMID: 32267052 PMCID: PMC7496815 DOI: 10.1002/cbic.202000159] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 04/07/2020] [Indexed: 12/02/2022]
Abstract
G‐Quadruplex (G4)‐forming DNA sequences have a tendency to form stable multimeric structures. This can be problematic for studies with synthetic oligodeoxynucleotides. Herein, we describe a method that quantitatively converts multimeric intermolecular structures of the Pu27 sequence from the c‐myc promoter into the desired monomeric G4 by alkaline treatment and refolding.
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Affiliation(s)
- Valerie Rauser
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany
| | - Elmar Weinhold
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany
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12
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Schnarr L, Jana J, Preckwinkel P, Weisz K. Impact of a Snap-Back Loop on Stability and Ligand Binding to a Parallel G-Quadruplex. J Phys Chem B 2020; 124:2778-2787. [DOI: 10.1021/acs.jpcb.0c00700] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Lena Schnarr
- Institute of Biochemistry, Universität Greifswald, Felix-Hausdorff-Strasse 4, D-17487 Greifswald, Germany
| | - Jagannath Jana
- Institute of Biochemistry, Universität Greifswald, Felix-Hausdorff-Strasse 4, D-17487 Greifswald, Germany
| | - Pit Preckwinkel
- Institute of Biochemistry, Universität Greifswald, Felix-Hausdorff-Strasse 4, D-17487 Greifswald, Germany
| | - Klaus Weisz
- Institute of Biochemistry, Universität Greifswald, Felix-Hausdorff-Strasse 4, D-17487 Greifswald, Germany
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13
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Chen B, Fountain G, Sullivan HJ, Paradis N, Wu C. To probe the binding pathway of a selective compound (D089-0563) to c-MYC Pu24 G-quadruplex using free ligand binding simulations and Markov state model analysis. Phys Chem Chem Phys 2020; 22:22567-22583. [DOI: 10.1039/d0cp03863f] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
D089-0563 is a highly promising anti-cancer compound that selectively binds the transcription-silencing G-quadruplex element (Pu27) at the promoter region of the human c-MYC oncogene; however, its binding mechanism remains elusive.
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Affiliation(s)
- Brian Chen
- Rowan University
- College of Science and Mathematics
- Glassboro
- USA
| | | | | | | | - Chun Wu
- Rowan University
- College of Science and Mathematics
- Glassboro
- USA
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14
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Giacalone JC, Andorf JL, Zhang Q, Burnight ER, Ochoa D, Reutzel AJ, Collins MM, Sheffield VC, Mullins RF, Han IC, Stone EM, Tucker BA. Development of a Molecularly Stable Gene Therapy Vector for the Treatment of RPGR-Associated X-Linked Retinitis Pigmentosa. Hum Gene Ther 2019; 30:967-974. [PMID: 31106594 PMCID: PMC6703244 DOI: 10.1089/hum.2018.244] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 04/12/2019] [Indexed: 12/16/2022] Open
Abstract
In a screen of 1,000 consecutively ascertained families, we recently found that mutations in the gene RPGR are the third most common cause of all inherited retinal disease. As the two most frequent disease-causing genes, ABCA4 and USH2A, are far too large to fit into clinically relevant adeno-associated virus (AAV) vectors, RPGR is an obvious early target for AAV-based ocular gene therapy. In generating plasmids for this application, we discovered that those containing wild-type RPGR sequence, which includes the highly repetitive low complexity region ORF15, were extremely unstable (i.e., they showed consistent accumulation of genomic changes during plasmid propagation). To develop a stable RPGR gene transfer vector, we used a bioinformatics approach to identify predicted regions of genomic instability within ORF15 (i.e., potential non-B DNA conformations). Synonymous substitutions were made in these regions to reduce the repetitiveness and increase the molecular stability while leaving the encoded amino acid sequence unchanged. The resulting construct was subsequently packaged into AAV serotype 5, and the ability to drive transcript expression and functional protein production was demonstrated via subretinal injection in rat and pull-down assays, respectively. By making synonymous substitutions within the repetitive region of RPGR, we were able to stabilize the plasmid and subsequently generate a clinical-grade gene transfer vector (IA-RPGR). Following subretinal injection in rat, we demonstrated that the augmented transcript was expressed at levels similar to wild-type constructs. By performing in vitro pull-down experiments, we were able to show that IA-RPGR protein product retained normal protein binding properties (i.e., analysis revealed normal binding to PDE6D, INPP5E, and RPGRIP1L). In summary, we have generated a stable RPGR gene transfer vector capable of producing functional RPGR protein, which will facilitate safety and toxicity studies required for progression to an Investigational New Drug application.
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Affiliation(s)
- Joseph C. Giacalone
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Jeaneen L. Andorf
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Qihong Zhang
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Erin R. Burnight
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Dalyz Ochoa
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Austin J. Reutzel
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Malia M. Collins
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Val C. Sheffield
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Robert F. Mullins
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Ian C. Han
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Edwin M. Stone
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, Carver College of Medicine, University of Iowa, Iowa City, Iowa
| | - Budd A. Tucker
- Department of Ophthalmology and Visual Sciences, Institute for Vision Research, Carver College of Medicine, University of Iowa, Iowa City, Iowa
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15
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Głuszyńska A, Juskowiak B, Kuta-Siejkowska M, Hoffmann M, Haider S. Carbazole ligands as c-myc G-quadruplex binders. Int J Biol Macromol 2018; 114:479-490. [DOI: 10.1016/j.ijbiomac.2018.03.135] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Revised: 03/16/2018] [Accepted: 03/21/2018] [Indexed: 10/24/2022]
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16
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Lee HT, Carr CE, Khutsishvili I, Marky LA. Effect of Loop Length and Sequence on the Stability of DNA Pyrimidine Triplexes with TAT Base Triplets. J Phys Chem B 2017; 121:9175-9184. [PMID: 28875701 DOI: 10.1021/acs.jpcb.7b07591] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We report the thermodynamic contributions of loop length and loop sequence to the overall stability of DNA intramolecular pyrimidine triplexes. Two sets of triplexes were designed: in the first set, the C5 loop closing the triplex stem was replaced with 5'-CTnC loops (n = 1-5), whereas in the second set, both the duplex and triplex loops were replaced with a 5'-GCAA or 5'-AACG tetraloop. For the triplexes with a 5'-CTnC loop, the triplex with five bases in the loop has the highest stability relative to the control. A loop length lower than five compromises the strength of the base-pair stacks without decreasing the thermal stability, leading to a decreased enthalpy, whereas an increase in the loop length leads to a decreased enthalpy and a higher entropic penalty. The incorporation of the GCAA loop yielded more stable triplexes, whereas the incorporation of AACG in the triplex loop yielded a less stable triplex due to an unfavorable enthalpy term. Thus, addition of the GCAA tetraloop can cause an increase in the thermodynamics of the triplex without affecting the sequence or melting behavior and may result in an additional layer of genetic regulation.
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Affiliation(s)
- Hui-Ting Lee
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
| | - Carolyn E Carr
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
| | - Irine Khutsishvili
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
| | - Luis A Marky
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
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Rigo R, Palumbo M, Sissi C. G-quadruplexes in human promoters: A challenge for therapeutic applications. Biochim Biophys Acta Gen Subj 2016; 1861:1399-1413. [PMID: 28025083 DOI: 10.1016/j.bbagen.2016.12.024] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 12/21/2016] [Accepted: 12/22/2016] [Indexed: 12/19/2022]
Abstract
BACKGROUND G-rich sequences undergo unique structural equilibria to form G-quadruplexes (G4) both in vitro and in cell systems. Several pathologies emerged to be directly related to G4 occurrence at defined genomic portions. Additionally, G-rich sequences are significantly represented around transcription start sites (TSS) thus leading to the hypothesis of a gene regulatory function for G4. Thus, the tuning of G4 formation has been proposed as a new powerful tool to regulate gene expression to treat related pathologies. However, up-to date this approach did not provide any new really efficient treatment. SCOPE OF REVIEW Here, we summarize the most recent advances on the correlation between the structural features of G4 in human promoters and the role these systems physiologically exert. In particular we focus on the effect of G4 localization among cell compartments and along the promoters in correlation with protein interaction networks and epigenetic state. Finally the intrinsic structural features of G4 at promoters are discussed to unveil the contribution of different G4 structural modules in this complex architecture. MAJOR CONCLUSIONS It emerges that G4s play several roles in the intriguing and complex mechanism of gene expression, being able to produce opposite effects on the same target. This reflects the occurrence of a highly variegate network of several components working simultaneously. GENERAL SIGNIFICANCE The resulting picture is still fuzzy but some points of strength are definitely emerging, which prompts all of us to strengthen our efforts in view of a selective control of gene expression through G4 modulation. This article is part of a Special Issue entitled "G-quadruplex" Guest Editor: Dr. Concetta Giancola and Dr. Daniela Montesarchio.
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Affiliation(s)
- Riccardo Rigo
- Dept. of Pharmaceutical and Pharmacological Sciences, University of Padova, v. Marzolo, 5, 35131 Padova, Italy
| | - Manlio Palumbo
- Dept. of Pharmaceutical and Pharmacological Sciences, University of Padova, v. Marzolo, 5, 35131 Padova, Italy
| | - Claudia Sissi
- Dept. of Pharmaceutical and Pharmacological Sciences, University of Padova, v. Marzolo, 5, 35131 Padova, Italy.
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18
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Rezzoug F, Thomas SD, Rouchka EC, Miller DM. Discovery of a Family of Genomic Sequences Which Interact Specifically with the c-MYC Promoter to Regulate c-MYC Expression. PLoS One 2016; 11:e0161588. [PMID: 27551915 PMCID: PMC4995011 DOI: 10.1371/journal.pone.0161588] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 08/08/2016] [Indexed: 12/14/2022] Open
Abstract
G-quadruplex forming sequences are particularly enriched in the promoter regions of eukaryotic genes, especially of oncogenes. One of the most well studied G-quadruplex forming sequences is located in the nuclease hypersensitive element (NHE) III1 of the c-MYC promoter region. The oncoprotein c-MYC regulates a large array of genes which play important roles in growth regulation and metabolism. It is dysregulated in >70% of human cancers. The silencer NHEIII1 located upstream of the P1 promoter regulates up-to 80% of c-MYC transcription and includes a G-quadruplex structure (Pu27) that is required for promoter inhibition. We have identified, for the first time, a family of seventeen G-quadruplex-forming motifs with >90% identity with Pu27, located on different chromosomes throughout the human genome, some found near or within genes involved in stem cell maintenance or neural cell development. Notably, all members of the Pu27 family interact specifically with NHEIII1 sequence, in vitro. Crosslinking studies demonstrate that Pu27 oligonucleotide binds specifically to the C-rich strand of the NHEIII1 resulting in the G-quadruplex structure stabilization. Pu27 homologous sequences (Pu27-HS) significantly inhibit leukemic cell lines proliferation in culture. Exposure of U937 cells to the Pu27-HS induces cell growth inhibition associated with cell cycle arrest that is most likely due to downregulation of c-MYC expression at the RNA and/or protein levels. Expression of SOX2, another gene containing a Pu27-HS, was affected by Pu27-HS treatment as well. Our data suggest that the oligonucleotides encoding the Pu27 family target complementary DNA sequences in the genome, including those of the c-MYC and SOX2 promoters. This effect is most likely cell type and cell growth condition dependent. The presence of genomic G-quadruplex-forming sequences homologous to Pu27 of c-MYC silencer and the fact that they interact specifically with the parent sequence suggest a common regulatory mechanism for genes whose promoters contain these sequences.
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Affiliation(s)
- Francine Rezzoug
- James Graham Brown Cancer Center, Department of Medicine, University of Louisville, Louisville Kentucky, United States of America
- * E-mail: (FR); (DMM)
| | - Shelia D. Thomas
- James Graham Brown Cancer Center, Department of Medicine, University of Louisville, Louisville Kentucky, United States of America
| | - Eric C. Rouchka
- Department of Computer Engineering and Computer Science, Speed School of Engineering, University of Louisville, Kentucky, United States of America
| | - Donald M. Miller
- James Graham Brown Cancer Center, Department of Medicine, University of Louisville, Louisville Kentucky, United States of America
- * E-mail: (FR); (DMM)
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Abstract
Since the first description of the canonical B-form DNA double helix, it has been suggested that alternative DNA, DNA–RNA, and RNA structures exist and act as functional genomic elements. Indeed, over the past few years it has become clear that, in addition to serving as a repository for genetic information, genomic DNA elicits biological responses by adopting conformations that differ from the canonical right-handed double helix, and by interacting with RNA molecules to form complex secondary structures. This review focuses on recent advances on three-stranded (triplex) nucleic acids, with an emphasis on DNA–RNA and RNA–RNA interactions. Emerging work reveals that triplex interactions between noncoding RNAs and duplex DNA serve as platforms for delivering site-specific epigenetic marks critical for the regulation of gene expression. Additionally, an increasing body of genetic and structural studies demonstrates that triplex RNA–RNA interactions are essential for performing catalytic and regulatory functions in cellular nucleoprotein complexes, including spliceosomes and telomerases, and for enabling protein recoding during programmed ribosomal frameshifting. Thus, evidence is mounting that DNA and RNA triplex interactions are implemented to perform a range of diverse biological activities in the cell, some of which will be discussed in this review.
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Affiliation(s)
- Albino Bacolla
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Dell Pediatric Research Institute, Austin, Texas, United States of America
| | - Guliang Wang
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Dell Pediatric Research Institute, Austin, Texas, United States of America
| | - Karen M. Vasquez
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Dell Pediatric Research Institute, Austin, Texas, United States of America
- * E-mail:
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20
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PIWIL2 induces c-Myc expression by interacting with NME2 and regulates c-Myc-mediated tumor cell proliferation. Oncotarget 2015; 5:8466-77. [PMID: 25193865 PMCID: PMC4226697 DOI: 10.18632/oncotarget.2327] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
c-Myc serves as a crucial regulator in multiple cellular events. Cumulative evidences demonstrate that anomalous c-Myc overexpression correlates with proliferation, invasion and metastasis in various human tumors. However, the transcriptionally activating mechanisms responsible for c-Myc overexpression are complex and continue to be intangible. Here we showed that Piwi-Like RNA-Mediated Gene Silencing 2 (PIWIL2) can upregulate c-Myc via binding with NME/NM23 nucleoside diphosphate kinase 2 (NME2). PIWIL2 promotes c-Myc transcription by interacting with and facilitating NME2 to bind to G4-motif region within c-Myc promoter. Interestingly, in a c-Myc-mediated manner, PIWIL2 upregulates RhoA, which in turn induces filamentary F-actin. Deficiency of PIWIL2 results in obstacle for c-Myc expression, cell cycle progress and cell proliferation. Taken together, our present work demonstrates that PIWIL2 modulates tumor cell proliferation and F-actin filaments via promoting c-Myc expression.
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Zhou J, Fleming AM, Averill AM, Burrows CJ, Wallace SS. The NEIL glycosylases remove oxidized guanine lesions from telomeric and promoter quadruplex DNA structures. Nucleic Acids Res 2015; 43:4039-54. [PMID: 25813041 PMCID: PMC4417164 DOI: 10.1093/nar/gkv252] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 03/11/2015] [Indexed: 12/31/2022] Open
Abstract
G-quadruplex is a four-stranded G-rich DNA structure that is highly susceptible to oxidation. Despite the important roles that G-quadruplexes play in telomere biology and gene transcription, neither the impact of guanine lesions on the stability of quadruplexes nor their repair are well understood. Here, we show that the oxidized guanine lesions 8-oxo-7,8-dihydroguanine (8-oxoG), guanidinohydantoin (Gh) and spiroiminodihydantoin (Sp) reduce the thermostability and alter the folding of telomeric quadruplexes in a location-dependent manner. Also, the NEIL1 and NEIL3 DNA glycosylases can remove hydantoin lesions but none of the glycosylases, including OGG1, are able to remove 8-oxoG from telomeric quadruplexes. Interestingly, a hydantoin lesion at the site most prone to oxidation in quadruplex DNA is not efficiently removed by NEIL1 or NEIL3. However, NEIL1, NEIL2 and NEIL3 remove hydantoins from telomeric quadruplexes formed by five TTAGGG repeats much more rapidly than the commonly studied four-repeat quadruplex structures. We also show that APE1 cleaves furan in selected positions in Na+-coordinated telomeric quadruplexes. In promoter G-quadruplex DNA, the NEIL glycosylases primarily remove Gh from Na+-coordinated antiparallel quadruplexes but not K+-coordinated parallel quadruplexes containing VEGF or c-MYC promoter sequences. Thus, the NEIL DNA glycosylases may be involved in both telomere maintenance and in gene regulation.
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Affiliation(s)
- Jia Zhou
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT 05405, USA
| | - Aaron M Fleming
- Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA
| | - April M Averill
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT 05405, USA
| | - Cynthia J Burrows
- Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA
| | - Susan S Wallace
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT 05405, USA
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Métifiot M, Amrane S, Litvak S, Andreola ML. G-quadruplexes in viruses: function and potential therapeutic applications. Nucleic Acids Res 2014; 42:12352-66. [PMID: 25332402 PMCID: PMC4227801 DOI: 10.1093/nar/gku999] [Citation(s) in RCA: 175] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 09/26/2014] [Accepted: 10/06/2014] [Indexed: 12/15/2022] Open
Abstract
G-rich nucleic acids can form non-canonical G-quadruplex structures (G4s) in which four guanines fold in a planar arrangement through Hoogsteen hydrogen bonds. Although many biochemical and structural studies have focused on DNA sequences containing successive, adjacent guanines that spontaneously fold into G4s, evidence for their in vivo relevance has recently begun to accumulate. Complete sequencing of the human genome highlighted the presence of ∼300,000 sequences that can potentially form G4s. Likewise, the presence of putative G4-sequences has been reported in various viruses genomes [e.g., Human immunodeficiency virus (HIV-1), Epstein-Barr virus (EBV), papillomavirus (HPV)]. Many studies have focused on telomeric G4s and how their dynamics are regulated to enable telomere synthesis. Moreover, a role for G4s has been proposed in cellular and viral replication, recombination and gene expression control. In parallel, DNA aptamers that form G4s have been described as inhibitors and diagnostic tools to detect viruses [e.g., hepatitis A virus (HAV), EBV, cauliflower mosaic virus (CaMV), severe acute respiratory syndrome virus (SARS), simian virus 40 (SV40)]. Here, special emphasis will be given to the possible role of these structures in a virus life cycle as well as the use of G4-forming oligonucleotides as potential antiviral agents and innovative tools.
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Affiliation(s)
- Mathieu Métifiot
- CNRS UMR-5234, Université de Bordeaux, 146 Rue Léo Saignat, 33076 Bordeaux, France
| | - Samir Amrane
- INSERM, U869, IECB, ARNA laboratory, Université de Bordeaux, 2 Rue Robert Escarpit 33600 Pessac, France
| | - Simon Litvak
- CNRS UMR-5234, Université de Bordeaux, 146 Rue Léo Saignat, 33076 Bordeaux, France
| | - Marie-Line Andreola
- CNRS UMR-5234, Université de Bordeaux, 146 Rue Léo Saignat, 33076 Bordeaux, France
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Du X, Gertz EM, Wojtowicz D, Zhabinskaya D, Levens D, Benham CJ, Schäffer AA, Przytycka TM. Potential non-B DNA regions in the human genome are associated with higher rates of nucleotide mutation and expression variation. Nucleic Acids Res 2014; 42:12367-79. [PMID: 25336616 PMCID: PMC4227770 DOI: 10.1093/nar/gku921] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
While individual non-B DNA structures have been shown to impact gene expression, their broad regulatory role remains elusive. We utilized genomic variants and expression quantitative trait loci (eQTL) data to analyze genome-wide variation propensities of potential non-B DNA regions and their relation to gene expression. Independent of genomic location, these regions were enriched in nucleotide variants. Our results are consistent with previously observed mutagenic properties of these regions and counter a previous study concluding that G-quadruplex regions have a reduced frequency of variants. While such mutagenicity might undermine functionality of these elements, we identified in potential non-B DNA regions a signature of negative selection. Yet, we found a depletion of eQTL-associated variants in potential non-B DNA regions, opposite to what might be expected from their proposed regulatory role. However, we also observed that genes downstream of potential non-B DNA regions showed higher expression variation between individuals. This coupling between mutagenicity and tolerance for expression variability of downstream genes may be a result of evolutionary adaptation, which allows reconciling mutagenicity of non-B DNA structures with their location in functionally important regions and their potential regulatory role.
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Affiliation(s)
- Xiangjun Du
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - E Michael Gertz
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Damian Wojtowicz
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Dina Zhabinskaya
- Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - David Levens
- UC Davis Genome Center, University of California Davis, Davis, CA 95616, USA
| | - Craig J Benham
- Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Alejandro A Schäffer
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Teresa M Przytycka
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
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24
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Su L, Zheng H, Li Z, Qiu J, Chen S, Liu J, Ou TM, Tan JH, Gu LQ, Huang ZS, Li D. Mechanistic studies on the anticancer activity of 2,4-disubstituted quinazoline derivative. Biochim Biophys Acta Gen Subj 2014; 1840:3123-30. [PMID: 25018006 DOI: 10.1016/j.bbagen.2014.07.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 06/23/2014] [Accepted: 07/02/2014] [Indexed: 12/11/2022]
Abstract
BACKGROUND Accelerated proliferation of solid tumor and hematologic cancer cells is related to accelerated transcription of ribosomal DNA by the RNA polymerase I to produce elevated level of ribosomal RNA. Therefore, down-regulation of RNA polymerase I transcription in cancer cells is an important anticancer therapeutic strategy. METHODS A variety of methods were used, including cloning, expression and purification of protein, electrophoretic mobility shift assay (EMSA), circular dichroic (CD) spectroscopy, CD-melting, isothermal titration calorimetry (ITC), chromatin immunoprecipitation (Ch-IP), RNA interference, RT-PCR, Western blot, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) cell assay. RESULTS Our results showed that 2,4-disubstituted quinazoline derivative Sysu12d could down-regulate c-myc through stabilization of c-myc promoter G-quadruplex, resulting in down-regulation of nucleolin expression. Sysu12d could also disrupt nucleolin/G-quadruplex complex. Both of the above contributed to the down-regulation of ribosomal RNA synthesis, followed by activation of p53 and then cancer cell apoptosis. CONCLUSIONS These mechanistic studies set up the basis for further development of Sysu12d as a new type of lead compound for cancer treatment. GENERAL SIGNIFICANCE 2,4-Disubstituted quinazoline derivatives may have multi-functional effect for cancer treatment.
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Affiliation(s)
- Lijuan Su
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Huaqin Zheng
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Zeng Li
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Jun Qiu
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Siqi Chen
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Jinggong Liu
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Tian-Miao Ou
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Jia-Heng Tan
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Lian-Quan Gu
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Zhi-Shu Huang
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China
| | - Ding Li
- School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, 132 Waihuan East Road, Guangzhou 510006, PR China.
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Yuan L, Tian T, Chen Y, Yan S, Xing X, Zhang Z, Zhai Q, Xu L, Wang S, Weng X, Yuan B, Feng Y, Zhou X. Existence of G-quadruplex structures in promoter region of oncogenes confirmed by G-quadruplex DNA cross-linking strategy. Sci Rep 2013; 3:1811. [PMID: 23657205 PMCID: PMC3648798 DOI: 10.1038/srep01811] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 04/22/2013] [Indexed: 01/23/2023] Open
Abstract
Existence of G-quadruplex DNA in vivo always attract widespread interest in the field of biology and biological chemistry. We reported our findings for the existence of G-quadruplex structures in promoter region of oncogenes confirmed by G-quadruplex DNA cross-linking strategy. Probes for selective G-quadruplex cross-linking was designed and synthesized that show high selectivity for G-quadruplex cross-linking. Further biological studies demonstrated its good inhibition activity against murine melanoma cells. To further investigate if G-quadruplex DNA was formed in vivo and as the target, a derivative was synthesized and pull-down process toward chromosome DNAs combined with circular dichroism and high throughput deep sequencing were performed. Several simulated intracellular conditions, including X. laevis oocytes, Ficoll 70 and PEG, was used to investigate the compound's pure cross-linking ability upon preformed G-quadruplex. Thus, as a potent G-quadruplex cross-linking agent, our strategy provided both valuable evidence of G-quadruplex structures in vivo and intense potential in anti-cancer therapy.
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Affiliation(s)
- Libo Yuan
- College of Chemistry and Molecular Sciences, Key Laboratory of Biomedical Polymers of Ministry of Education, Wuhan University, Wuhan, Hubei, 430072, P R China
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26
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Cui J, Waltman P, Le VH, Lewis EA. The effect of molecular crowding on the stability of human c-MYC promoter sequence I-motif at neutral pH. Molecules 2013; 18:12751-67. [PMID: 24132198 PMCID: PMC6270392 DOI: 10.3390/molecules181012751] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Revised: 09/26/2013] [Accepted: 10/10/2013] [Indexed: 12/20/2022] Open
Abstract
We have previously shown that c-MYC promoter sequences can form stable i-motifs in acidic solution (pH 4.5-5.5). In terms of drug targeting, the question is whether c-MYC promoter sequence i-motifs will exist in the nucleus at neutral pH. In this work, we have investigated the stability of a mutant c-MYC i-motif in solutions containing a molecular crowding agent. The crowded nuclear environment was modeled by the addition of up to 40% w/w polyethylene glycols having molecular weights up to 12,000 g/mol. CD and DSC were used to establish the presence and stability of c-MYC i-motifs in buffer solutions over the pH range 4 to 7. We have shown that the c-MYC i-motif can exist as a stable structure at pH values as high as 6.7 in crowded solutions. Generic dielectric constant effects, e.g., a shift in the pKa of cytosine by more than 2 units (e.g., 4.8 to 7.0), or the formation of non-specific PEG/DNA complexes appear to contribute insignificantly to i-motif stabilization. Molecular crowding, largely an excluded volume effect of added PEG, having a molecular weight in excess of 1,000 g/mol, appears to be responsible for stabilizing the more compact i-motif over the random coil at higher pH values.
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Affiliation(s)
- Jingjing Cui
- Department of Chemistry, Mississippi State University, Mississippi State, MS 39762, USA.
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Shalaby T, Fiaschetti G, Nagasawa K, Shin-ya K, Baumgartner M, Grotzer M. G-quadruplexes as potential therapeutic targets for embryonal tumors. Molecules 2013; 18:12500-37. [PMID: 24152672 PMCID: PMC6269990 DOI: 10.3390/molecules181012500] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 09/18/2013] [Accepted: 09/25/2013] [Indexed: 12/27/2022] Open
Abstract
Embryonal tumors include a heterogeneous group of highly malignant neoplasms that primarily affect infants and children and are characterized by a high rate of mortality and treatment-related morbidity, hence improved therapies are clearly needed. G-quadruplexes are special secondary structures adopted in guanine (G)-rich DNA sequences that are often present in biologically important regions, e.g. at the end of telomeres and in the regulatory regions of oncogenes such as MYC. Owing to the significant roles that both telomeres and MYC play in cancer cell biology, G-quadruplexes have been viewed as emerging therapeutic targets in oncology and as tools for novel anticancer drug design. Several compounds that target these structures have shown promising anticancer activity in tumor xenograft models and some of them have entered Phase II clinical trials. In this review we examine approaches to DNA targeted cancer therapy, summarize the recent developments of G-quadruplex ligands as anticancer drugs and speculate on the future direction of such structures as a potential novel therapeutic strategy for embryonal tumors of the nervous system.
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Affiliation(s)
- Tarek Shalaby
- Division of Oncology, University Children's Hospital of Zurich, Zurich 8032, Switzerland.
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28
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Wang L, Wei C. Spectroscopic and Biological Studies of Phenanthroline Compounds: Selective Recognition of Gene-Promoter G-Quadruplex DNAs Preferred over Duplex DNA. Chem Biodivers 2013; 10:1154-64. [DOI: 10.1002/cbdv.201200341] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Indexed: 11/06/2022]
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29
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Du X, Wojtowicz D, Bowers AA, Levens D, Benham CJ, Przytycka TM. The genome-wide distribution of non-B DNA motifs is shaped by operon structure and suggests the transcriptional importance of non-B DNA structures in Escherichia coli. Nucleic Acids Res 2013; 41:5965-77. [PMID: 23620297 PMCID: PMC3695496 DOI: 10.1093/nar/gkt308] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Although the right-handed double helical B-form DNA is most common under physiological conditions, DNA is dynamic and can adopt a number of alternative structures, such as the four-stranded G-quadruplex, left-handed Z-DNA, cruciform and others. Active transcription necessitates strand separation and can induce such non-canonical forms at susceptible genomic sequences. Therefore, it has been speculated that these non-B DNA motifs can play regulatory roles in gene transcription. Such conjecture has been supported in higher eukaryotes by direct studies of several individual genes, as well as a number of large-scale analyses. However, the role of non-B DNA structures in many lower organisms, in particular proteobacteria, remains poorly understood and incompletely documented. In this study, we performed the first comprehensive study of the occurrence of B DNA-non-B DNA transition-susceptible sites (non-B DNA motifs) within the context of the operon structure of the Escherichia coli genome. We compared the distributions of non-B DNA motifs in the regulatory regions of operons with those from internal regions. We found an enrichment of some non-B DNA motifs in regulatory regions, and we show that this enrichment cannot be simply explained by base composition bias in these regions. We also showed that the distribution of several non-B DNA motifs within intergenic regions separating divergently oriented operons differs from the distribution found between convergent ones. In particular, we found a strong enrichment of cruciforms in the termination region of operons; this enrichment was observed for operons with Rho-dependent, as well as Rho-independent terminators. Finally, a preference for some non-B DNA motifs was observed near transcription factor-binding sites. Overall, the conspicuous enrichment of transition-susceptible sites in these specific regulatory regions suggests that non-B DNA structures may have roles in the transcriptional regulation of specific operons within the E. coli genome.
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Affiliation(s)
- Xiangjun Du
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health 8600 Rockville Pike, Bethesda, MD 20894, USA
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30
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Gai W, Yang Q, Xiang J, Sun H, Shang Q, Li Q, Jiang W, Guan A, Zhang H, Tang Y, Xu G. Roles of flanking sequences in the binding between unimolecular parallel-stranded G-quadruplexes and ligands. ACTA ACUST UNITED AC 2013. [DOI: 10.1007/s11434-012-5639-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Yang H, Zhong HJ, Leung KH, Chan DSH, Ma VPY, Fu WC, Nanjunda R, Wilson WD, Ma DL, Leung CH. Structure-based design of flavone derivatives as c-myc oncogene down-regulators. Eur J Pharm Sci 2013; 48:130-41. [DOI: 10.1016/j.ejps.2012.10.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2011] [Revised: 09/19/2012] [Accepted: 10/02/2012] [Indexed: 12/21/2022]
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32
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Chen WJ, Zhou CX, Yao PF, Wang XX, Tan JH, Li D, Ou TM, Gu LQ, Huang ZS. Disubstituted 1,8-dipyrazolcarbazole derivatives as a new type of c-myc G-quadruplex binding ligands. Bioorg Med Chem 2012; 20:2829-36. [PMID: 22484007 DOI: 10.1016/j.bmc.2012.03.031] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2012] [Revised: 03/13/2012] [Accepted: 03/14/2012] [Indexed: 11/19/2022]
Abstract
A series of 1,8-dipyrazolcarbazole (DPC) derivatives (6a-6d, 7a-7d) designed as G-quadruplex ligands have been synthesized and characterized. The FRET-melting and SPR results showed that the DPC derivatives could well recognize G-quadruplex with strong discrimination against the duplex DNA. In addition, the DPC derivatives showed much stronger stabilization activities and binding affinities for c-myc G-quadruplex rather than telomeric G-quadruplex. Therefore, their interactions with c-myc G-quadruplex were further explored by means of CD spectroscopy, PCR-stop assay, and molecular modeling. In cellular studies, all compounds showed strong cytotoxicity against cancer cells, while weak cytotoxicity towards normal cells. RT-PCR assay showed that compound 7b could down-regulate c-myc gene expression in Ramos cell line, while had no effect on c-myc expression in CA46 cell line with NHE III(1) element removed, indicating its effective binding with G-quadruplex on c-myc oncogene in vivo.
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Affiliation(s)
- Wei-Jia Chen
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou 510006, People's Republic of China
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33
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Regulation of the equilibrium between G-quadruplex and duplex DNA in promoter of human c-myc oncogene by a pyrene derivative. Int J Biol Macromol 2011; 49:1173-6. [PMID: 21683090 DOI: 10.1016/j.ijbiomac.2011.05.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2011] [Revised: 05/21/2011] [Accepted: 05/24/2011] [Indexed: 11/22/2022]
Abstract
It has been established that the equilibrium between duplex and G-quadruplex of the nuclease hypersensitivity element III1 (NHE III1) in human c-myc promoter is linked with this gene's transcription. Using NMR and ESI-MS, we have found a pyrene derivative, DMAPP, is able to modulate this equilibrium and, thus, might have the potential to regulate this oncogene's transcription. DMAPP has shown as a G-quadruplex binding agent and could induce c-myc G-quadruplex formation out of duplex. These results provide new clue for rational drug design to target transcription control of c-myc.
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34
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Chan DSH, Yang H, Kwan MHT, Cheng Z, Lee P, Bai LP, Jiang ZH, Wong CY, Fong WF, Leung CH, Ma DL. Structure-based optimization of FDA-approved drug methylene blue as a c-myc G-quadruplex DNA stabilizer. Biochimie 2011; 93:1055-64. [DOI: 10.1016/j.biochi.2011.02.013] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Accepted: 02/24/2011] [Indexed: 12/20/2022]
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35
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Kaluzhny DN, Shchyolkina AK, Ilyinsky NS, Borisova OF, Shtil AA. Novel Indolocarbazole Derivative 12-(α-L-arabinopyranosyl)indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7-dione Is a Preferred c-Myc Guanine Quadruplex Ligand. J Nucleic Acids 2011; 2011:184735. [PMID: 21772991 PMCID: PMC3136114 DOI: 10.4061/2011/184735] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Accepted: 03/04/2011] [Indexed: 12/31/2022] Open
Abstract
The indolocarbazole derivative 12-(α-L-arabinopyranosyl)indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7-dione (AIC) has demonstrated a high potency (at nanomolar to submicromolar concentrations) towards the NCI panel of human tumor cell lines and transplanted tumors. Intercalation into the DNA double helix has been identified as an important prerequisite for AIC cytotoxicity. In this study, we provide evidence for preferential binding to the G-quadruplex derived from the c-Myc oncogene promoter (Pu18 d(AG(3)TG(4))(2); G-c-Myc). The association constant for AIC:G-c-Myc complex was ~100 times and 10 times greater than the respective values for the complexes AIC:c-Myc duplex and AIC:telomeric d(TTAGGG)(4) G-quadruplex. The concentrations at which AIC formed complexes with G-c-Myc were close to those that attenuated the steady-state level of the c-Myc mRNA in the human HCT116 colon carcinoma cell line. We suggest that preferential binding of AIC to G-c-Myc rather than to the c-Myc duplex might favor the quadruplex formation in the cells, thereby contributing to downregulation of the c-Myc expression by AIC.
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Affiliation(s)
- Dmitry N Kaluzhny
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 32 Vavilov Street, Moscow 119991, Russia
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36
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Chemical and structural biology of nucleic acids and protein-nucleic acid complexes for novel drug discovery. Sci China Chem 2011. [DOI: 10.1007/s11426-010-4174-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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37
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Peng D, Tan JH, Chen SB, Ou TM, Gu LQ, Huang ZS. Bisaryldiketene derivatives: A new class of selective ligands for c-myc G-quadruplex DNA. Bioorg Med Chem 2010; 18:8235-42. [DOI: 10.1016/j.bmc.2010.10.021] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2010] [Revised: 10/05/2010] [Accepted: 10/05/2010] [Indexed: 12/11/2022]
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38
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Lee HM, Chan DSH, Yang F, Lam HY, Yan SC, Che CM, Ma DL, Leung CH. Identification of natural product fonsecin B as a stabilizing ligand of c-myc G-quadruplex DNA by high-throughput virtual screening. Chem Commun (Camb) 2010; 46:4680-2. [PMID: 20383387 DOI: 10.1039/b926359d] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Fonsecin B has been identified as stabilizing ligand of c-myc G-quadruplex DNA using high-throughput virtual screening of a natural product database, and inhibited Taq polymerase-mediated DNA extension in vitro through stabilization of the G-quadruplex secondary structure.
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Affiliation(s)
- Ho-Man Lee
- Department of Chemistry and Open Laboratory of Chemical Biology of the Institute of Molecular Technology for Drug Discovery and Synthesis, The University of Hong Kong, Pokfulam Road, Hong Kong
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39
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Abstract
c-MYC is an important regulator of a wide array of cellular processes necessary for normal cell growth and differentiation, and its dysregulation is one of the hallmarks of many cancers. Consequently, understanding c-MYC transcriptional activation is critical for understanding developmental and cancer biology, as well as for the development of new anticancer drugs. The nuclease hypersensitive element (NHE) III(1) region of the c-MYC promoter has been shown to be particularly important in regulating c-MYC expression. Specifically, the formation of a G-quadruplex structure appears to promote repression of c-MYC transcription. This review focuses on what is known about the formation of a G-quadruplex in the NHE III(1) region of the c-MYC promoter, as well as on those factors that are known to modulate its formation. Last, we discuss the development of small molecules that stabilize or induce the formation of G-quadruplex structures and could potentially be used as anticancer agents.
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40
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Shalaby T, von Bueren AO, Hürlimann ML, Fiaschetti G, Castelletti D, Masayuki T, Nagasawa K, Arcaro A, Jelesarov I, Shin-ya K, Grotzer M. Disabling c-Myc in childhood medulloblastoma and atypical teratoid/rhabdoid tumor cells by the potent G-quadruplex interactive agent S2T1-6OTD. Mol Cancer Ther 2010; 9:167-79. [PMID: 20053783 DOI: 10.1158/1535-7163.mct-09-0586] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We investigated here the effects of S2T1-6OTD, a novel telomestatin derivative that is synthesized to target G-quadruplex-forming DNA sequences, on a representative panel of human medulloblastoma (MB) and atypical teratoid/rhabdoid (AT/RT) childhood brain cancer cell lines. S2T1-6OTD proved to be a potent c-Myc inhibitor through its high-affinity physical interaction with the G-quadruplex structure in the c-Myc promoter. Treatment with S2T1-6OTD reduced the mRNA and protein expressions of c-Myc and hTERT, which is transcriptionally regulated by c-Myc, and decreased the activities of both genes. In remarkable contrast to control cells, short-term (72-hour) treatment with S2T1-6OTD resulted in a dose- and time-dependent antiproliferative effect in all MB and AT/RT brain tumor cell lines tested (IC(50), 0.25-0.39 micromol/L). Under conditions where inhibition of both proliferation and c-Myc activity was observed, S2T1-6OTD treatment decreased the protein expression of the cell cycle activator cyclin-dependent kinase 2 and induced cell cycle arrest. Long-term treatment (5 weeks) with nontoxic concentrations of S2T1-6OTD resulted in a time-dependent (mainly c-Myc-dependent) telomere shortening. This was accompanied by cell growth arrest starting on day 28 followed by cell senescence and induction of apoptosis on day 35 in all of the five cell lines investigated. On in vivo animal testing, S2T1-6OTD may well represent a novel therapeutic strategy for childhood brain tumors.
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Affiliation(s)
- Tarek Shalaby
- Department of Oncology, University Children's Hospital Zurich, Zurich, Switzerland
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41
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González V, Guo K, Hurley L, Sun D. Identification and characterization of nucleolin as a c-myc G-quadruplex-binding protein. J Biol Chem 2009; 284:23622-35. [PMID: 19581307 PMCID: PMC2749137 DOI: 10.1074/jbc.m109.018028] [Citation(s) in RCA: 233] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Revised: 07/02/2009] [Indexed: 11/06/2022] Open
Abstract
myc is a proto-oncogene that plays an important role in the promotion of cellular growth and proliferation. Understanding the regulation of c-myc is important in cancer biology, as it is overexpressed in a wide variety of human cancers, including most gynecological, breast, and colon cancers. We previously demonstrated that a guanine-rich region upstream of the P1 promoter of c-myc that controls 85-90% of the transcriptional activation of this gene can form an intramolecular G-quadruplex (G4) that functions as a transcriptional repressor element. In this study, we used an affinity column to purify proteins that selectively bind to the human c-myc G-quadruplex. We found that nucleolin, a multifunctional phosphoprotein, binds in vitro to the c-myc G-quadruplex structure with high affinity and selectivity when compared with other known quadruplex structures. In addition, we demonstrate that upon binding, nucleolin facilitates the formation and increases the stability of the c-myc G-quadruplex structure. Furthermore, we provide evidence that nucleolin overexpression reduces the activity of a c-myc promoter in plasmid presumably by inducing and stabilizing the formation of the c-myc G-quadruplex. Finally, we show that nucleolin binds to the c-myc promoter in HeLa cells, which indicates that this interaction occurs in vivo. In summary, nucleolin may induce c-myc G4 formation in vivo.
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Affiliation(s)
| | - Kexiao Guo
- Department of Biochemistry and Molecular Biophysics, University of Arizona, Tucson, Arizona 85721
| | - Laurence Hurley
- From the College of Pharmacy and
- BIO5 Institute, Tucson, Arizona 85721, and
- Arizona Cancer Center, Tucson, Arizona 85724
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42
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Dexheimer TS, Carey SS, Zuohe S, Gokhale VM, Hu X, Murata LB, Maes EM, Weichsel A, Sun D, Meuillet EJ, Montfort WR, Hurley LH. NM23-H2 may play an indirect role in transcriptional activation of c-myc gene expression but does not cleave the nuclease hypersensitive element III(1). Mol Cancer Ther 2009; 8:1363-77. [PMID: 19435876 DOI: 10.1158/1535-7163.mct-08-1093] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The formation of G-quadruplex structures within the nuclease hypersensitive element (NHE) III(1) region of the c-myc promoter and the ability of these structures to repress c-myc transcription have been well established. However, just how these extremely stable DNA secondary structures are transformed to activate c-myc transcription is still unknown. NM23-H2/nucleoside diphosphate kinase B has been recognized as an activator of c-myc transcription via interactions with the NHE III(1) region of the c-myc gene promoter. Through the use of RNA interference, we confirmed the transcriptional regulatory role of NM23-H2. In addition, we find that further purification of NM23-H2 results in loss of the previously identified DNA strand cleavage activity, but retention of its DNA binding activity. NM23-H2 binds to both single-stranded guanine- and cytosine-rich strands of the c-myc NHE III(1) and, to a lesser extent, to a random single-stranded DNA template. However, it does not bind to or cleave the NHE III(1) in duplex form. Significantly, potassium ions and compounds that stabilize the G-quadruplex and i-motif structures have an inhibitory effect on NM23-H2 DNA-binding activity. Mutation of Arg(88) to Ala(88) (R88A) reduced both DNA and nucleotide binding but had minimal effect on the NM23-H2 crystal structure. On the basis of these data and molecular modeling studies, we have proposed a stepwise trapping-out of the NHE III(1) region in a single-stranded form, thus allowing single-stranded transcription factors to bind and activate c-myc transcription. Furthermore, this model provides a rationale for how the stabilization of the G-quadruplex or i-motif structures formed within the c-myc gene promoter region can inhibit NM23-H2 from activating c-myc gene expression.
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43
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Jain A, Wang G, Vasquez KM. DNA triple helices: biological consequences and therapeutic potential. Biochimie 2008; 90:1117-30. [PMID: 18331847 DOI: 10.1016/j.biochi.2008.02.011] [Citation(s) in RCA: 198] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Accepted: 02/08/2008] [Indexed: 01/25/2023]
Abstract
DNA structure is a critical element in determining its function. The DNA molecule is capable of adopting a variety of non-canonical structures, including three-stranded (i.e. triplex) structures, which will be the focus of this review. The ability to selectively modulate the activity of genes is a long-standing goal in molecular medicine. DNA triplex structures, either intermolecular triplexes formed by binding of an exogenously applied oligonucleotide to a target duplex sequence, or naturally occurring intramolecular triplexes (H-DNA) formed at endogenous mirror repeat sequences, present exploitable features that permit site-specific alteration of the genome. These structures can induce transcriptional repression and site-specific mutagenesis or recombination. Triplex-forming oligonucleotides (TFOs) can bind to duplex DNA in a sequence-specific fashion with high affinity, and can be used to direct DNA-modifying agents to selected sequences. H-DNA plays important roles in vivo and is inherently mutagenic and recombinogenic, such that elements of the H-DNA structure may be pharmacologically exploitable. In this review we discuss the biological consequences and therapeutic potential of triple helical DNA structures. We anticipate that the information provided will stimulate further investigations aimed toward improving DNA triplex-related gene targeting strategies for biotechnological and potential clinical applications.
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Affiliation(s)
- Aklank Jain
- Department of Carcinogenesis, University of Texas, M.D. Anderson Cancer Center, Science Park--Research Division, 1808 Park Road 1-C, P.O. Box 389, Smithville, TX 78957, USA
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44
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45
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Abstract
Myc regulates to some degree every major process in the cell. Proliferation, growth, differentiation, apoptosis, and metabolism are all under myc control. In turn, these processes feed back to adjust the level of c-myc expression. Although Myc is regulated at every level from RNA synthesis to protein degradation, c-myc transcription is particularly responsive to multiple diverse physiological and pathological signals. These signals are delivered to the c-myc promoter by a wide variety of transcription factors and chromatin remodeling complexes. How these diverse and sometimes disparate signals are processed to manage the output of the c-myc promoter involves chromatin, recruitment of the transcription machinery, post-initiation transcriptional regulation, and mechanisms to provide dynamic feedback. Understanding these mechanisms promises to add new dimensions to models of transcriptional control and to reveal new strategies to manipulate Myc levels.
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Affiliation(s)
- J Liu
- Gene Regulation Section, Laboratory of Pathology, NCI, DCS, Bldg. 10, Rm 2N106, Bethesda, MD 20892-1500, USA
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46
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Phan AT, Kuryavyi V, Gaw HY, Patel DJ. Small-molecule interaction with a five-guanine-tract G-quadruplex structure from the human MYC promoter. Nat Chem Biol 2005; 1:167-73. [PMID: 16408022 PMCID: PMC4690526 DOI: 10.1038/nchembio723] [Citation(s) in RCA: 424] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2005] [Accepted: 06/24/2005] [Indexed: 12/29/2022]
Abstract
It has been widely accepted that DNA can adopt other biologically relevant structures beside the Watson-Crick double helix. One recent important example is the guanine-quadruplex (G-quadruplex) structure formed by guanine tracts found in the MYC (or c-myc) promoter region, which regulates the transcription of the MYC oncogene. Stabilization of this G-quadruplex by ligands, such as the cationic porphyrin TMPyP4, decreases the transcriptional level of MYC. Here, we report the first structure of a DNA fragment containing five guanine tracts from this region. An unusual G-quadruplex fold, which was derived from NMR restraints using unambiguous model-independent resonance assignment approaches, involves a core of three stacked guanine tetrads formed by four parallel guanine tracts with all anti guanines and a snapback 3'-end syn guanine. We have determined the structure of the complex formed between this G-quadruplex and TMPyP4. This structural information, combined with details of small-molecule interaction, provides a platform for the design of anticancer drugs targeting multi-guanine-tract sequences that are found in the MYC and other oncogenic promoters, as well as in telomeres.
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Affiliation(s)
- Anh Tuân Phan
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
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47
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Phan AT, Modi YS, Patel DJ. Propeller-type parallel-stranded G-quadruplexes in the human c-myc promoter. J Am Chem Soc 2004; 126:8710-6. [PMID: 15250723 PMCID: PMC4692381 DOI: 10.1021/ja048805k] [Citation(s) in RCA: 426] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The nuclease-hypersensitivity element III1 in the c-myc promoter is a good anticancer target since it largely controls transcriptional activation of the important c-myc oncogene. Recently, the guanine-rich strand of this element has been shown to form an equilibrium between G-quadruplex structures built from two different sets of G-stretches; two models of intramolecular fold-back antiparallel-stranded G-quadruplexes, called "basket" and "chair" forms, were proposed. Here, we show by NMR that two sequences containing these two sets of G-stretches form intramolecular propeller-type parallel-stranded G-quadruplexes in K(+)-containing solution. The two structures involve a core of three stacked G-tetrads formed by four parallel G-stretches with all anti guanines and three double-chain-reversal loops bridging three G-tetrad layers. The central loop contains two or six residues, while the two other loops contain only one residue.
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Affiliation(s)
- Anh Tuân Phan
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
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48
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Zahedi K, Prada AE, Mulligan A, Prada JA, Davis AE. Normal transcription of the C1 inhibitor gene is dependent upon a polypurine-polypyrimidine region within the promoter. Inflammation 2002; 26:183-91. [PMID: 12184632 DOI: 10.1023/a:1016519813252] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Analysis of the transcriptional activity of C1 inhibitor (CIINH) promoter reporter constructs with mutations in the R-Y region indicate that triplex formation by this region is not a predictor of transcriptional activity and that normal promoter function depends on the interaction of trans acting factors with specific elements within this region. Electrophoretic mobility shift assay (EMSA) of Hep3B nuclear extracts using the wild type promoter probe (nucleotides -98 to -9) yielded four major bands. Incubation of the same extracts with probes lacking the HNF-1 site resulted in the disappearance of one band. Supershift assays indicate that HNF-1alpha is the only previously identified protein that is present in the EMSA bands. Southwestern blot analysis detected four bands (M(r)s -130, 75, 65 and 20 kDa). These data suggest that the -98 to -9 region of the C1INH promoter interacts with at least four proteins, one of which is HNF-1alpha.
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Affiliation(s)
- Kamyar Zahedi
- Division of Nephrology and Hypertension, Children's Hospital Research Foundation, Cincinnati, Ohio 45229, USA.
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49
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Fabregat I, Koch KS, Aoki T, Atkinson AE, Dang H, Amosova O, Fresco JR, Schildkraut CL, Leffert HL. Functional pleiotropy of an intramolecular triplex-forming fragment from the 3'-UTR of the rat Pigr gene. Physiol Genomics 2001; 5:53-65. [PMID: 11242589 DOI: 10.1152/physiolgenomics.2001.5.2.53] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
A microsatellite-containing 359-bp restriction fragment, isolated from the rat Pigr gene (murine polymeric immunoglobulin receptor gene) 3'-untranslated region (3'-UTR) and inserted into 3'-UTR or 3' flanking positions in transcription units of supercoiled plasmids, attenuates luciferase reporter gene expression in orientation- and position-dependent ways following transient transfection of human 293 cells. The same fragment stimulates orientation-dependent gene expression in a 5' flanking position. Plasmid linearization abrogates both orientation- and position-dependent responses. Cell-free translation reveals that 5' and 3' flanking expression responses are proportional to increased and decreased luciferase mRNA levels, whereas 3'-UTR expression is associated with control mRNA levels. Hypersensitivity to nucleases S1 and P1, gel mobility differences between supercoiled plasmids carrying opposing microsatellite orientations, and anomalous melting profiles of this fragment are also observed. These results suggest that functional pleiotropy of this fragment depends on the DNA context of its purine-rich microsatellite strand and on DNA supercoiling. Intramolecular triplexes stabilized by supercoiling and secondary structures of purine repeat-rich mRNAs may also confer regulatory properties to similar genomic elements.
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Affiliation(s)
- I Fabregat
- Department of Bioquimica y Biologia Molecular, Instituto de Bioquimica, Centro Mixto CSIC/UCM, Facultad de Farmacia, Universidad Complutense, 28040 Madrid, Spain
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50
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Rangan A, Fedoroff OY, Hurley LH. Induction of duplex to G-quadruplex transition in the c-myc promoter region by a small molecule. J Biol Chem 2001; 276:4640-6. [PMID: 11035006 DOI: 10.1074/jbc.m005962200] [Citation(s) in RCA: 162] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A major control element of the human c-myc oncogene is the nuclease-hypersensitive purine/pyrimidine-rich sequence. This double-stranded DNA fragment, corresponding to the 27-base pair segment in the nuclease-hypersensitive element of the c-myc promoter region, forms a stable Watson-Crick double helix under physiological conditions. However, this duplex DNA can be effectively converted to G-quadruplex DNA by a small molecular weight ligand. Both intermolecular and intramolecular G-quadruplex forms can be induced by this ligand. Similar transitional changes are also observed with the duplex telomeric sequence from the Oxytricha species. These results provide additional support to the idea that G-quadruplex structures may play structural roles in vivo and also provide insight into novel methodologies for rational drug design. These structurally altered DNA elements might serve as regulatory signals in gene expression or in telomere dynamics and hence are promising targets for drug action.
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Affiliation(s)
- A Rangan
- Division of Medicinal Chemistry, College of Pharmacy, University of Texas, Austin, TX 78712, USA
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