1
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Wang JX, Wang XD, Hu MH. Novel quinoxaline analogs as telomeric G-quadruplex ligands exert antitumor effects related to enhanced immunomodulation. Eur J Med Chem 2024; 274:116536. [PMID: 38805936 DOI: 10.1016/j.ejmech.2024.116536] [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: 04/12/2024] [Revised: 05/21/2024] [Accepted: 05/25/2024] [Indexed: 05/30/2024]
Abstract
G-quadruplexes (G4s) are commonly formed in the G-rich strand of telomeric DNA. Ligands targeting telomeric G4 induce DNA damage and telomere dysfunction, which makes them potential antitumor drugs. New telomeric G4 ligands with drug-likeness are still needed to be exploited, especially with their antitumor mechanisms thoroughly discussed. In this study, a novel series of quinoxaline analogs were rationally designed and synthesized. Among them, R1 was the most promising ligand for its cytotoxic effects on tumor cells and stabilizing ability with telomeric G4. Cellular assays illustrated that R1 stabilized G4 and induced R-loop accumulation in the telomeric regions, subsequently triggering DNA damage responses, cell cycle arrest in G2/M phase, apoptosis and antiproliferation. Moreover, R1 evoked immunogenic cell death (ICD) in tumor cells, which promoted the maturation of bone marrow derived dendritic cells (BMDCs). In breast cancer mouse model, R1 exhibited a significant decrease in tumor burden through the immunomodulatory effects, including the increase of CD4+ and CD8+ T cells in tumors and cytokine levels in sera. Our research provides a new idea that targeting telomeric G4 induces DNA damage responses, causing antitumor effects both in vitro and in vivo, partially due to the enhancement of immunomodulation.
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Affiliation(s)
- Jia-Xin Wang
- Nation-Regional Engineering Lab for Synthetic Biology of Medicine, International Cancer Center, School of Pharmacy, Shenzhen University Medical School, Shenzhen, 518060, China
| | - Xiao-Dong Wang
- Nation-Regional Engineering Lab for Synthetic Biology of Medicine, International Cancer Center, School of Pharmacy, Shenzhen University Medical School, Shenzhen, 518060, China
| | - Ming-Hao Hu
- Nation-Regional Engineering Lab for Synthetic Biology of Medicine, International Cancer Center, School of Pharmacy, Shenzhen University Medical School, Shenzhen, 518060, China.
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2
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Michael Sabo T, Trent JO, Chaires JB, Monsen RC. Strategy for modeling higher-order G-quadruplex structures recalcitrant to NMR determination. Methods 2024; 230:9-20. [PMID: 39032720 DOI: 10.1016/j.ymeth.2024.07.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 06/22/2024] [Accepted: 07/17/2024] [Indexed: 07/23/2024] Open
Abstract
Guanine-rich nucleic acids can form intramolecularly folded four-stranded structures known as G-quadruplexes (G4s). Traditionally, G4 research has focused on short, highly modified DNA or RNA sequences that form well-defined homogeneous compact structures. However, the existence of longer sequences with multiple G4 repeats, from proto-oncogene promoters to telomeres, suggests the potential for more complex higher-order structures with multiple G4 units that might offer selective drug-targeting sites for therapeutic development. These larger structures present significant challenges for structural characterization by traditional high-resolution methods like multi-dimensional NMR and X-ray crystallography due to their molecular complexity. To address this current challenge, we have developed an integrated structural biology (ISB) platform, combining experimental and computational methods to determine self-consistent molecular models of higher-order G4s (xG4s). Here we outline our ISB method using two recent examples from our lab, an extended c-Myc promoter and long human telomere G4 repeats, that highlights the utility and generality of our approach to characterizing biologically relevant xG4s.
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Affiliation(s)
- T Michael Sabo
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY, United States
| | - John O Trent
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY, United States
| | - Jonathan B Chaires
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY, United States
| | - Robert C Monsen
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY, United States.
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3
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Zhang Z, Mlýnský V, Krepl M, Šponer J, Stadlbauer P. Mechanical Stability and Unfolding Pathways of Parallel Tetrameric G-Quadruplexes Probed by Pulling Simulations. J Chem Inf Model 2024; 64:3896-3911. [PMID: 38630447 PMCID: PMC11094737 DOI: 10.1021/acs.jcim.4c00227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 04/02/2024] [Accepted: 04/02/2024] [Indexed: 05/14/2024]
Abstract
Guanine quadruplex (GQ) is a noncanonical nucleic acid structure formed by guanine-rich DNA and RNA sequences. Folding of GQs is a complex process, where several aspects remain elusive, despite being important for understanding structure formation and biological functions of GQs. Pulling experiments are a common tool for acquiring insights into the folding landscape of GQs. Herein, we applied a computational pulling strategy─steered molecular dynamics (SMD) simulations─in combination with standard molecular dynamics (MD) simulations to explore the unfolding landscapes of tetrameric parallel GQs. We identified anisotropic properties of elastic conformational changes, unfolding transitions, and GQ mechanical stabilities. Using a special set of structural parameters, we found that the vertical component of pulling force (perpendicular to the average G-quartet plane) plays a significant role in disrupting GQ structures and weakening their mechanical stabilities. We demonstrated that the magnitude of the vertical force component depends on the pulling anchor positions and the number of G-quartets. Typical unfolding transitions for tetrameric parallel GQs involve base unzipping, opening of the G-stem, strand slippage, and rotation to cross-like structures. The unzipping was detected as the first and dominant unfolding event, and it usually started at the 3'-end. Furthermore, results from both SMD and standard MD simulations indicate that partial spiral conformations serve as a transient ensemble during the (un)folding of GQs.
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Affiliation(s)
- Zhengyue Zhang
- Institute
of Biophysics of the Czech Academy of Sciences, Královopolská 135, Brno 61200, Czech Republic
- CEITEC−Central
European Institute of Technology, Masaryk
University, Kamenice
5, Brno 625 00, Czech Republic
- National
Center for Biomolecular Research,
Faculty of Science, Masaryk University, Kamenice 5, Brno 625 00, Czech Republic
| | - Vojtěch Mlýnský
- Institute
of Biophysics of the Czech Academy of Sciences, Královopolská 135, Brno 61200, Czech Republic
| | - Miroslav Krepl
- Institute
of Biophysics of the Czech Academy of Sciences, Královopolská 135, Brno 61200, Czech Republic
| | - Jiří Šponer
- Institute
of Biophysics of the Czech Academy of Sciences, Královopolská 135, Brno 61200, Czech Republic
| | - Petr Stadlbauer
- Institute
of Biophysics of the Czech Academy of Sciences, Královopolská 135, Brno 61200, Czech Republic
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4
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Wang C, Xu G, Liu X, Jiang L, Zhou X, Liu M, Li C. 19F Nuclear Magnetic Resonance Fingerprinting Technique for Identifying and Quantifying G-Quadruplex Topology in Human Telomeric Overhangs. J Am Chem Soc 2024; 146:4741-4751. [PMID: 38346932 DOI: 10.1021/jacs.3c12247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
G-quadruplexes (G4s) are noncanonical nucleic acid secondary structures with diverse topological features and biological roles. Human telomeric (Htelo) overhangs consisting of TTAGGG repeats can fold into G4s that adopt different topologies under physiological conditions. These G4s are potential targets for anticancer drugs. Despite intensive research, the existence and topology of G4s at Htelo overhangs in vivo are still unclear because there is no method to distinguish and quantify the topology of Htelo overhangs with native lengths that can form more than three tandem G4s in living cells. Herein, we present a novel 19F chemical shift fingerprinting technique to identify and quantify the topology of the Htelo overhangs up to five G-quadruplexes (G4s) and 120 nucleotides long both in vitro and in living cells. Our results show that longer overhang sequences tend to form stable G4s at the 5'- and 3'-ends, while the interior G4s are dynamic and "sliding" along the sequence, with TTA or 1-3 TTAGGG repeats as a linker. Each G4 in the longer overhang is conformationally heterogeneous, but the predominant ones are hybrid-2, two- or three-tetrad antiparallel, and hybrid-1 at the 5'-terminal, interior, and 3'-terminal, respectively. Additionally, we observed a distinct behavior of different lengths of telomeric sequences in living cells, suggesting that the overhang length and protein accessibility are related to its function. This technique provides a powerful tool for quickly identifying the folding topology and relative population of long Htelo overhangs, which may provide valuable insights into telomere functionality and be beneficial for structure-based anticancer drug development targeting G4s.
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Affiliation(s)
- Chen Wang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Guohua Xu
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China
| | - Xiaoli Liu
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China
| | - Ling Jiang
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China
| | - Xin Zhou
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China
| | - Maili Liu
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China
| | - Conggang Li
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan National Laboratory for Optoelectronics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China
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5
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Shiekh S, Kodikara SG, Balci H. Structure, Topology, and Stability of Multiple G-quadruplexes in Long Telomeric Overhangs. J Mol Biol 2024; 436:168205. [PMID: 37481156 PMCID: PMC10799177 DOI: 10.1016/j.jmb.2023.168205] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 07/05/2023] [Accepted: 07/12/2023] [Indexed: 07/24/2023]
Abstract
Telomeres and their single stranded overhangs gradually shorten with successive cell divisions, as part of the natural aging process, but can be elongated by telomerase, a nucleoprotein complex which is activated in the majority of cancers. This prominent implication in cancer and aging has made the repetitive telomeric sequences (TTAGGG repeats) and the G-quadruplex structures that form in their overhangs the focus of intense research in the past several decades. However, until recently most in vitro efforts to understand the structure, stability, dynamics, and interactions of telomeric overhangs had been focused on short sequences that are not representative of longer sequences encountered in a physiological setting. In this review, we will provide a broad perspective about telomeres and associated factors, and introduce the agents and structural characteristics involved in organizing, maintaining, and protecting telomeric DNA. We will also present a summary of recent research performed on long telomeric sequences, nominally defined as those that can form two or more tandem G-quadruplexes, i.e., which contain eight or more TTAGGG repeats. Results of experimental studies using a broad array of experimental tools, in addition to recent computational efforts will be discussed, particularly in terms of their implications for the stability, folding topology, and compactness of the tandem G-quadruplexes that form in long telomeric overhangs.
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Affiliation(s)
- Sajad Shiekh
- Department of Physics, Kent State University, Kent, OH 44242, USA
| | | | - Hamza Balci
- Department of Physics, Kent State University, Kent, OH 44242, USA.
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6
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Yarawsky AE, Dinu V, Harding SE, Herr AB. Strong non-ideality effects at low protein concentrations: considerations for elongated proteins. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2023; 52:427-438. [PMID: 37055656 PMCID: PMC10599268 DOI: 10.1007/s00249-023-01648-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 03/17/2023] [Accepted: 03/29/2023] [Indexed: 04/15/2023]
Abstract
A recent investigation was aimed at obtaining structural information on a highly extended protein via SEC-MALS-SAXS. Significantly broadened elution peaks were observed, reminiscent of a phenomenon known as viscous fingering. This phenomenon is usually observed above 50 mg/mL for proteins like bovine serum albumin (BSA). Interestingly, the highly extended protein (Brpt5.5) showed viscous fingering at concentrations lower than 5 mg/mL. The current study explores this and other non-ideal behavior, emphasizing the presence of these effects at relatively low concentrations for extended proteins. BSA, Brpt5.5, and a truncated form of Brpt5.5 referred to as Brpt1.5 are studied systematically using size-exclusion chromatography (SEC), sedimentation velocity analytical ultracentrifugation (AUC), and viscosity. The viscous fingering effect is quantified using two approaches and is found to correlate well with the intrinsic viscosity of the proteins-Brpt5.5 exhibits the most severe effect and is the most extended protein tested in the study. By AUC, the hydrodynamic non-ideality was measured for each protein via global analysis of a concentration series. Compared to BSA, both Brpt1.5 and Brpt5.5 showed significant non-ideality that could be easily visualized at concentrations at or below 5 mg/mL and 1 mg/mL, respectively. A variety of relationships were examined for their ability to differentiate the proteins by shape using information from AUC and/or viscosity. Furthermore, these relationships were also tested in the context of hydrodynamic modeling. The importance of considering non-ideality when investigating the structure of extended macromolecules is discussed.
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Affiliation(s)
- Alexander E Yarawsky
- Division of Immunobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
- BioAnalysis, LLC, 3401 I Street Suite 206, Philadelphia, PA, 19134, USA.
| | - Vlad Dinu
- National Centre for Macromolecular Hydrodynamics (NCMH), University of Nottingham, Sutton Bonington, Loughborough, LE12 5RD, UK
| | - Stephen E Harding
- National Centre for Macromolecular Hydrodynamics (NCMH), University of Nottingham, Sutton Bonington, Loughborough, LE12 5RD, UK
| | - Andrew B Herr
- Division of Immunobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
- Division of Infectious Diseases, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
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7
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Monsen RC. Higher-order G-quadruplexes in promoters are untapped drug targets. Front Chem 2023; 11:1211512. [PMID: 37351517 PMCID: PMC10282141 DOI: 10.3389/fchem.2023.1211512] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 05/30/2023] [Indexed: 06/24/2023] Open
Abstract
G-quadruplexes (G4s) are four-stranded nucleic acid secondary structures that form within guanine-rich regions of chromatin. G4 motifs are abundant in the genome, with a sizable proportion (∼40%) existing within gene promoter regions. G4s are proven epigenetic features that decorate the promoter landscape as binding centers for transcription factors. Stabilizing or disrupting promoter G4s can directly influence adjacent gene transcription, making G4s attractive as indirect drug targets for hard-to-target proteins, particularly in cancer. However, no G4 ligands have progressed through clinical trials, mostly owing to off targeting effects. A major hurdle in G4 drug discovery is the lack of distinctiveness of the small monomeric G4 structures currently used as receptors. This mini review describes and contrasts monomeric and higher-order G-quadruplex structure and function and provides a rationale for switching focus to the higher-order forms as selective molecular targets. The human telomerase reverse transcriptase (hTERT) core promoter G-quadruplex is then used as a case study that highlights the potential for higher-order G4s as selective indirect inhibitors of hard-to-target proteins in cancer.
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8
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Kench T, Rakers V, Bouzada D, Gomez-González J, Robinson J, Kuimova MK, Vázquez López M, Vázquez ME, Vilar R. Dimeric Metal-Salphen Complexes Which Target Multimeric G-Quadruplex DNA. Bioconjug Chem 2023; 34:911-921. [PMID: 37119235 DOI: 10.1021/acs.bioconjchem.3c00114] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
G-Quadruplex DNA structures have attracted increasing attention due to their biological roles and potential as targets for the development of new drugs. While most guanine-rich sequences in the genome have the potential to form monomeric G-quadruplexes, certain sequences have enough guanine-tracks to give rise to multimeric quadruplexes. One of these sequences is the human telomere where tandem repeats of TTAGGG can lead to the formation of two or more adjacent G-quadruplexes. Herein we report on the modular synthesis via click chemistry of dimeric metal-salphen complexes (with NiII and PtII) bridged by either polyether or peptide linkers. We show by circular dichroism (CD) spectroscopy that they generally have higher selectivity for dimeric vs monomeric G-quadruplexes. The emissive properties of the PtII-salphen dimeric complexes have been used to study their interactions with monomeric and dimeric G-quadruplexes in vitro as well as to study their cellular uptake and localization.
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Affiliation(s)
- Timothy Kench
- Department of Chemistry, Imperial College London, White City Campus, 82 Wood Lane, London W12 0BZ, United Kingdom
| | - Viktoria Rakers
- Department of Chemistry, Imperial College London, White City Campus, 82 Wood Lane, London W12 0BZ, United Kingdom
| | - David Bouzada
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS), Departamento de Química Orgánica, Universidade de Santiago de Compostela, Santiago de Compostela 15782, Spain
| | - Jacobo Gomez-González
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS), Departamento de Química Orgánica, Universidade de Santiago de Compostela, Santiago de Compostela 15782, Spain
| | - Jenna Robinson
- Department of Chemistry, Imperial College London, White City Campus, 82 Wood Lane, London W12 0BZ, United Kingdom
| | - Marina K Kuimova
- Department of Chemistry, Imperial College London, White City Campus, 82 Wood Lane, London W12 0BZ, United Kingdom
| | - Miguel Vázquez López
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS), Departamento de Química Inorgánica, Universidade de Santiago de Compostela, Santiago de Compostela 15782, Spain
| | - M Eugenio Vázquez
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS), Departamento de Química Orgánica, Universidade de Santiago de Compostela, Santiago de Compostela 15782, Spain
| | - Ramon Vilar
- Department of Chemistry, Imperial College London, White City Campus, 82 Wood Lane, London W12 0BZ, United Kingdom
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9
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Monsen RC, Chua ED, Hopkins J, Chaires J, Trent J. Structure of a 28.5 kDa duplex-embedded G-quadruplex system resolved to 7.4 Å resolution with cryo-EM. Nucleic Acids Res 2023; 51:1943-1959. [PMID: 36715343 PMCID: PMC9976903 DOI: 10.1093/nar/gkad014] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 12/16/2022] [Accepted: 01/04/2023] [Indexed: 01/31/2023] Open
Abstract
Genomic regions with high guanine content can fold into non-B form DNA four-stranded structures known as G-quadruplexes (G4s). Extensive in vivo investigations have revealed that promoter G4s are transcriptional regulators. Little structural information exists for these G4s embedded within duplexes, their presumed genomic environment. Here, we report the 7.4 Å resolution structure and dynamics of a 28.5 kDa duplex-G4-duplex (DGD) model system using cryo-EM, molecular dynamics, and small-angle X-ray scattering (SAXS) studies. The DGD cryo-EM refined model features a 53° bend induced by a stacked duplex-G4 interaction at the 5' G-tetrad interface with a persistently unstacked 3' duplex. The surrogate complement poly dT loop preferably stacks onto the 3' G-tetrad interface resulting in occlusion of both 5' and 3' tetrad interfaces. Structural analysis shows that the DGD model is quantifiably more druggable than the monomeric G4 structure alone and represents a new structural drug target. Our results illustrate how the integration of cryo-EM, MD, and SAXS can reveal complementary detailed static and dynamic structural information on DNA G4 systems.
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Affiliation(s)
- Robert C Monsen
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - Eugene Y D Chua
- National Center for CryoEM Access and Training (NCCAT), Simons Electron Microscopy Center, New York Structural Biology Center, NY 10027, USA
| | - Jesse B Hopkins
- The Biophysics Collaborative Access Team (BioCAT), Department of Biological, Chemical, and Physical Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Jonathan B Chaires
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
- Department of Medicine, University of Louisville, Louisville, KY 40202, USA
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40202, USA
| | - John O Trent
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
- Department of Medicine, University of Louisville, Louisville, KY 40202, USA
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40202, USA
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10
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Zheng BX, Yu J, Long W, Chan KH, Leung ASL, Wong WL. Structurally diverse G-quadruplexes as the noncanonical nucleic acid drug target for live cell imaging and antibacterial study. Chem Commun (Camb) 2023; 59:1415-1433. [PMID: 36636928 DOI: 10.1039/d2cc05945b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The formation of G-quadruplex structures (G4s) in vitro from guanine (G)-rich nucleic acid sequences of DNA and RNA stabilized with monovalent cations, typically K+ and Na+, under physiological conditions, has been verified experimentally and some of them have high-resolution NMR or X-ray crystal structures; however, the biofunction of these special noncanonical secondary structures of nucleic acids has not been fully understood and their existence in vivo is still controversial at present. It is generally believed that the folding and unfolding of G4s in vivo is a transient process. Accumulating evidence has shown that G4s may play a role in the regulation of certain important cellular functions including telomere maintenance, replication, transcription and translation. Therefore, both DNA and RNA G4s of human cancer hallmark genes are recognized as the potential anticancer drug target for the investigation in cancer biology, chemical biology and drug discovery. The relationship between the sequence, structure and stability of G4s, the interaction of G4s with small molecules, and insights into the rational design of G4-selective binding ligands have been intensively studied over the decade. At present, some G4-ligands have achieved a new milestone and successfully entered the human clinical trials for anticancer therapy. Over the past few decades, numerous efforts have been devoted to anticancer therapy; however, G4s for molecular recognition and live cell imaging and for application as antibacterial agents and antibiofilms against antibiotic resistance have been obviously underexplored. The recent advances in G4-ligands in these areas are thus selected and discussed concentratedly in this article in order to shed light on the emerging role of G4s in chemical biology and therapeutic prospects against bacterial infections. In addition, the recently published molecular scaffolds for designing small ligands selectively targeting G4s in live cell imaging, bacterial biofilm imaging, and antibacterial studies are discussed. Furthermore, a number of underexplored G4-targets from the cytoplasmic membrane-associated DNA, the conserved promoter region of K. pneumoniae genomes, the RNA G4-sites in the transcriptome of E. coli and P. aeruginosa, and the mRNA G4-sites in the sequence for coding the vital bacterial FtsZ protein are highlighted to further explore in G4-drug development against human diseases.
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Affiliation(s)
- Bo-Xin Zheng
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China.
| | - Jie Yu
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China.
| | - Wei Long
- The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen 518057, P. R. China
| | - Ka Hin Chan
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China.
| | - Alan Siu-Lun Leung
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China.
| | - Wing-Leung Wong
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China. .,The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen 518057, P. R. China
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11
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Kristoffersen E, Coletta A, Lund L, Schiøtt B, Birkedal V. Inhibited complete folding of consecutive human telomeric G-quadruplexes. Nucleic Acids Res 2023; 51:1571-1582. [PMID: 36715345 PMCID: PMC9976873 DOI: 10.1093/nar/gkad004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 12/24/2022] [Accepted: 01/04/2023] [Indexed: 01/31/2023] Open
Abstract
Noncanonical DNA structures, termed G-quadruplexes, are present in human genomic DNA and are important elements in many DNA metabolic processes. Multiple sites in the human genome have G-rich DNA stretches able to support formation of several consecutive G-quadruplexes. One of those sites is the telomeric overhang region that has multiple repeats of TTAGGG and is tightly associated with both cancer and aging. We investigated the folding of consecutive G-quadruplexes in both potassium- and sodium-containing solutions using single-molecule FRET spectroscopy, circular dichroism, thermal melting and molecular dynamics simulations. Our observations show coexistence of partially and fully folded DNA, the latter consisting of consecutive G-quadruplexes. Following the folding process over hours in sodium-containing buffers revealed fast G-quadruplex folding but slow establishment of thermodynamic equilibrium. We find that full consecutive G-quadruplex formation is inhibited by the many DNA structures randomly nucleating on the DNA, some of which are off-path conformations that need to unfold to allow full folding. Our study allows describing consecutive G-quadruplex formation in both nonequilibrium and equilibrium conditions by a unified picture, where, due to the many possible DNA conformations, full folding with consecutive G-quadruplexes as beads on a string is not necessarily achieved.
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Affiliation(s)
- Emil Laust Kristoffersen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus, Denmark
| | - Andrea Coletta
- Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus, Denmark
| | - Line Mørkholt Lund
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus, Denmark
| | - Birgit Schiøtt
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus, Denmark,Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus, Denmark
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12
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Monsen RC, Trent JO, Chaires JB. G-quadruplex DNA: A Longer Story. Acc Chem Res 2022; 55:3242-3252. [PMID: 36282946 DOI: 10.1021/acs.accounts.2c00519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
G-quadruplexes (G4s) are distinctive four-stranded DNA or RNA structures found within cells that are thought to play functional roles in gene regulation and transcription, translation, recombination, and DNA damage/repair. While G4 structures can be uni-, bi-, or tetramolecular with respect to strands, folded unimolecular conformations are most significant in vivo. Unimolecular G4 can potentially form in sequences with runs of guanines interspersed with what will become loops in the folded structure: 5'GxLyGxLyGxLyGx, where x is typically 2-4 and y is highly variable. Such sequences are highly conserved and specifically located in genomes. In the folded structure, guanines from each run combine to form planar tetrads with four hydrogen-bonded guanine bases; these tetrads stack on one another to produce four strand segments aligned in specific parallel or antiparallel orientations, connected by the loop sequences. Three types of loops (lateral, diagonal, or "propeller") have been identified. The stacked tetrads form a central cavity that features strong coordination sites for monovalent cations that stabilize the G4 structure, with potassium or sodium preferred. A single monomeric G4 typically forms from a sequence containing roughly 20-30 nucleotides. Such short sequences have been the primary focus of X-ray crystallographic or NMR studies that have produced high-resolution structures of a variety of monomeric G4 conformations. These structures are often used as the basis for drug design efforts to modulate G4 function.We believe that the focus on monomeric G4 structures formed by such short sequences is perhaps myopic. Such short sequences for structural studies are often arbitrarily selected and removed from their native genomic sequence context, and then are often changed from their native sequences by base substitutions or deletions intended to optimize the formation of a homogeneous G4 conformation. We believe instead that G-quadruplexes prefer company and that in a longer natural sequence context multiple adjacent G4 units can form to combine into more complex multimeric G4 structures with richer topographies than simple monomeric forms. Bioinformatic searches of the human genome show that longer sequences with the potential for forming multiple G4 units are common. Telomeric DNA, for example, has a single-stranded overhang of hundreds of nucleotides with the requisite repetitive sequence with the potential for formation of multiple G4s. Numerous extended promoter sequences have similar potentials for multimeric G4 formation. X-ray crystallography and NMR methods are challenged by these longer sequences (>30 nt), so other tools are needed to explore the possible multimeric G4 landscape. We have implemented an integrated structural biology approach to address this challenge. This approach integrates experimental biophysical results with atomic-level molecular modeling and molecular dynamics simulations that provide quantitatively testable model structures. In every long sequence we have studied so far, we found that multimeric G4 structures readily form, with a surprising diversity of structures dependent on the exact native sequence used. In some cases, stable hairpin duplexes form along with G4 units to provide an even richer landscape. This Account provides an overview of our approach and recent progress and provides a new perspective on the G-quadruplex folding landscape.
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Affiliation(s)
- Robert C Monsen
- UofL Health Brown Cancer Center, University of Louisville, 505 S. Hancock St., Louisville, Kentucky 40202, United States
| | - John O Trent
- UofL Health Brown Cancer Center, University of Louisville, 505 S. Hancock St., Louisville, Kentucky 40202, United States.,Department of Medicine, University of Louisville, 505 S. Hancock St., Louisville, Kentucky 40202, United States.,Department of Biochemistry and Molecular Genetics, University of Louisville, 505 S. Hancock St., Louisville, Kentucky 40202, United States
| | - Jonathan B Chaires
- UofL Health Brown Cancer Center, University of Louisville, 505 S. Hancock St., Louisville, Kentucky 40202, United States.,Department of Medicine, University of Louisville, 505 S. Hancock St., Louisville, Kentucky 40202, United States.,Department of Biochemistry and Molecular Genetics, University of Louisville, 505 S. Hancock St., Louisville, Kentucky 40202, United States
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13
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Chen L, Dickerhoff J, Sakai S, Yang D. DNA G-Quadruplex in Human Telomeres and Oncogene Promoters: Structures, Functions, and Small Molecule Targeting. Acc Chem Res 2022; 55:2628-2646. [PMID: 36054116 PMCID: PMC9937053 DOI: 10.1021/acs.accounts.2c00337] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
DNA G-quadruplex secondary structures formed in guanine-rich human telomeres and oncogene promoters are functionally important and have emerged as a promising new class of cancer-specific drug targets. These globular intramolecular structures are stabilized by K+ or Na+ and form readily under physiological solution conditions. Moreover, G-quadruplexes are epigenetic features and can alter chromatin structure and function together with interactive proteins. Here, we discuss our efforts over the last two decades to understand the structures and functions of DNA G-quadruplexes formed in key oncogene promoters and human telomeres and their interactions with small molecules. Using high-field NMR spectroscopy, we determined the high-resolution structures of physiologically relevant telomeric G-quadruplexes in K+ solution with a major form (hybrid-2) and a minor form (hybrid-1), as well as a two-tetrad intermediate. The intrinsic structural polymorphism of telomeric DNA may be important for the biology of human telomeres, and we proposed a model for the interconversion. More recently, we have worked on G-quadruplexes of MYC, BCL2, PDGFR-β, VEGF, and k-RAS oncogene promoters. We determined the structure of the major G-quadruplex formed in the MYC promoter, a prototype for parallel G-quadruplexes. It is the first example of the parallel-stranded G3NG3 structure motif with a 1-nt loop, which is prevalent in promoter sequences and likely evolutionarily selected to initiate folding. Remarkably, the parallel MYC promoter G-quadruplexes are highly stable. Additionally, we determined the molecular structures of G-quadruplexes formed in human BCL2, VEGF, and PDGFR-β promoters, each adopting a unique structure. For example, the BCL2 promoter contains distinct interchangeable G-quadruplexes in two adjacent regions, suggesting precise regulation by different proteins. The PDGFR-β promoter adopts unique "broken-strand" and vacancy G-quadruplexes, which can be recognized by cellular guanine metabolites for a potential regulatory role.Structural information on G-quadruplexes in complex with small-molecules is critical for understanding specific recognition and structure-based rational drug design. Our studies show that many G-quadruplexes contain unique structural features such as capping and loop structures, allowing specific recognition by drugs and protein. This represents a paradigm shift in understanding DNA as a drug target: Rather than a uniform, nonselective binding site in duplex DNA, the G-quadruplex is being pursued as a new class of selectively targetable drug receptors. We focus on targeting the biologically relevant MYC promoter G-quadruplex (MycG4) with small molecules and have determined its first and additional drug complex structures. Very recently, we have discovered clinically tested indenoisoquinolines as strong MycG4 binders and potent MYC inhibitors. We have also discovered drugs targeting the unique dGMP-bound-vG4 formed in the PDGFR-β promoter. Moreover, we determined the complex structures of the first small molecules that specifically recognize the physiologically relevant human telomeric G-quadruplexes. Unlike the previously recognized dogma that the optimal G-quadruplex ligands are large aromatic or cyclic compounds, our results suggest that smaller asymmetric compounds with appropriate functional groups are better choices to specifically bind G-quadruplexes. This body of work lays a strong foundation for future work aimed at understanding the cellular functions of G-quadruplexes and G-quadruplex-targeted drug design.
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Affiliation(s)
- Luying Chen
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, 575 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
| | - Jonathan Dickerhoff
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, 575 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
| | - Saburo Sakai
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, 575 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
- Biogeochemistry Research Center, Japan Agency for Marine-Earth Science and Technology, 2-15, Natsushima-cho, Yokosuka-city, Kanagawa 237-0061, Japan
| | - Danzhou Yang
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, 575 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
- Purdue Center for Cancer Research, Purdue University, 201 University Street, West Lafayette, Indiana 47907, United States
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
- Purdue Institute for Drug Discovery, Purdue University, 720 Clinic Drive, West Lafayette, Indiana 47907, United States
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14
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Cozzaglio M, Ceschi S, Groaz E, Sturlese M, Sissi C. G-quadruplexes formation within the promoter of TEAD4 oncogene and their interaction with Vimentin. Front Chem 2022; 10:1008075. [PMID: 36186582 PMCID: PMC9520404 DOI: 10.3389/fchem.2022.1008075] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 08/24/2022] [Indexed: 11/13/2022] Open
Abstract
G-quadruplexes (G4s) are nucleic acid secondary structures detected within human chromosomes, that cluster at gene promoters and enhancers. This suggests that G4s may play specific roles in the regulation of gene expression. Within a distinct subgroup of G-rich domains, the formation of two or more adjacent G4 units (G4-repeats) is feasible. Recently it was shown that Vimentin, a protein highly expressed within mesenchymal cells, selectively recognizes these arrangements. Putative G4-repeats have been searched within the human gene proximal promoters by the bioinformatics tool QPARSE and they resulted to be enriched at genes related to epithelial-to-mesenchymal transition (EMT). This suggested that Vimentin binding at these sites might be relevant for the maintenance of the mesenchymal phenotype. Among all the identified sequences, in the present study we selected the one located within the promoter of the TEAD4 oncogene. TEAD4 codifies for a transcriptional enhancer factor, TEAD4, that actively promotes EMT, supporting, cell proliferation and migration. Moreover, in colorectal cancer cells TEAD4 directly enhances the expression of Vimentin. Thus, the possible interaction of Vimentin with TEAD4 promoter could highlight a positive feedback loop between these two factors, associated to important tumor metastasis related events. Here, we exploited spectroscopic and electrophoretic measurements under different conditions to address the folding behavior of the selected sequence. This allowed us to validate the folding of TEAD4 promoter into a G4-repeat able to interact with Vimentin.
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Affiliation(s)
- Marta Cozzaglio
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
| | - Silvia Ceschi
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
| | - Elisabetta Groaz
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
- KU Leuven, Rega Institute for Medical Research, KU Leuven, Medicinal Chemistry, Leuven, Belgium
| | - Mattia Sturlese
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
| | - Claudia Sissi
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova, Italy
- *Correspondence: Claudia Sissi,
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15
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Xiong K, Ouyang C, Liu J, Karges J, Lin X, Chen X, Chen Y, Wan J, Ji L, Chao H. Chiral RuII‐PtII Complexes Inducing Telomere Dysfunction against Cisplatin‐Resistant Cancer Cells. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202204866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Kai Xiong
- Sun Yat-Sen University School of Chemistry CHINA
| | - Cheng Ouyang
- Sun Yat-Sen University School of Chemistry CHINA
| | - Jiaqi Liu
- Central China Normal University College of Chemistry CHINA
| | | | - Xinlin Lin
- Sun Yat-Sen University School of Chemistry CHINA
| | - Xiang Chen
- Sun Yat-Sen University School of Chemistry CHINA
| | - Yu Chen
- Sun Yat-Sen University School of Chemistry CHINA
| | - Jian Wan
- Central China Normal University College of Chemistry CHINA
| | - Liangnian Ji
- Sun Yat-Sen University School of Chemistry CHINA
| | - Hui Chao
- Sun Yat-Sen University Chemistry Xingang Xilu 135# 510275 Guangzhou CHINA
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16
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Xiong K, Ouyang C, Liu J, Karges J, Lin X, Chen X, Chen Y, Wan J, Ji L, Chao H. Chiral Ru II -Pt II Complexes Inducing Telomere Dysfunction against Cisplatin-Resistant Cancer Cells. Angew Chem Int Ed Engl 2022; 61:e202204866. [PMID: 35736788 DOI: 10.1002/anie.202204866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Indexed: 11/06/2022]
Abstract
The application of G-quadruplex stabilizers presents a promising anticancer strategy. However, the molecular crowding conditions within cells diminish the potency of current G-quadruplex stabilizers. Herein, chiral RuII -PtII dinuclear complexes were developed as highly potent G-quadruplex stabilizers even under challenging molecular crowding conditions. The compounds were encapsulated with biotin-functionalized DNA cages to enhance sub-cellular localization and provide cancer selectivity. The nanoparticles were able to efficiently inhibit the endogenous activities of telomerase in cisplatin-resistant cancer cells and cause cell death by apoptosis. The nanomaterials demonstrated high antitumor activity towards cisplatin-resistant tumor cells as well as tumor-bearing mice. To the best of our knowledge, this study presents the first example of a RuII -PtII dinuclear complex as a G-quadruplex stabilizer with an anti-cancer effect towards drug-resistant tumors inside an animal model.
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Affiliation(s)
- Kai Xiong
- MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry, Guangdong Provincial Key Laboratory of Digestive Cancer Research, The Seventh Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510006, P. R. China
| | - Cheng Ouyang
- MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry, Guangdong Provincial Key Laboratory of Digestive Cancer Research, The Seventh Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510006, P. R. China
| | - Jiaqi Liu
- College of Chemistry, Central China Normal University, Wuhan, 430079, P. R. China
| | - Johannes Karges
- Department of Chemistry and, Biochemistry University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Xinlin Lin
- MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry, Guangdong Provincial Key Laboratory of Digestive Cancer Research, The Seventh Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510006, P. R. China
| | - Xiang Chen
- MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry, Guangdong Provincial Key Laboratory of Digestive Cancer Research, The Seventh Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510006, P. R. China
| | - Yu Chen
- MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry, Guangdong Provincial Key Laboratory of Digestive Cancer Research, The Seventh Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510006, P. R. China
| | - Jian Wan
- College of Chemistry, Central China Normal University, Wuhan, 430079, P. R. China
| | - Liangnian Ji
- MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry, Guangdong Provincial Key Laboratory of Digestive Cancer Research, The Seventh Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510006, P. R. China
| | - Hui Chao
- MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry, Guangdong Provincial Key Laboratory of Digestive Cancer Research, The Seventh Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510006, P. R. China.,MOE Key Laboratory of Theoretical Organic Chemistry and Functional Molecule, School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan, 400201, P. R. China
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17
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Monsen RC, Maguire JM, DeLeeuw LW, Chaires JB, Trent JO. Drug discovery of small molecules targeting the higher-order hTERT promoter G-quadruplex. PLoS One 2022; 17:e0270165. [PMID: 35709230 PMCID: PMC9202945 DOI: 10.1371/journal.pone.0270165] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 06/03/2022] [Indexed: 12/15/2022] Open
Abstract
DNA G-quadruplexes (G4s) are now widely accepted as viable targets in the pursuit of anticancer therapeutics. To date, few small molecules have been identified that exhibit selectivity for G4s over alternative forms of DNA, such as the ubiquitous duplex. We posit that the lack of current ligand specificity arises for multiple reasons: G4 atomic models are often small, monomeric, single quadruplex structures with few or no druggable pockets; targeting G-tetrad faces frequently results in the enrichment of extended electron-deficient polyaromatic end-pasting scaffolds; and virtual drug discovery efforts often under-sample chemical search space. We show that by addressing these issues we can enrich for non-standard molecular templates that exhibit high selectivity towards G4s over other forms of DNA. We performed an extensive virtual screen against the higher-order hTERT core promoter G4 that we have previously characterized, targeting 12 of its unique loop and groove pockets using libraries containing 40 million drug-like compounds for each screen. Using our drug discovery funnel approach, which utilizes high-throughput fluorescence thermal shift assay (FTSA) screens, microscale thermophoresis (MST), and orthogonal biophysical methods, we have identified multiple unique G4 binding scaffolds. We subsequently used two rounds of catalogue-based SAR to increase the affinity of a disubstituted 2-aminoethyl-quinazoline that stabilizes the higher-order hTERT G-quadruplex by binding across its G4 junctional sites. We show selectivity of its binding affinity towards hTERT is virtually unaffected in the presence of near-physiological levels of duplex DNA, and that this molecule downregulates hTERT transcription in breast cancer cells.
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Affiliation(s)
- Robert C. Monsen
- UofL Health Brown Cancer Center, University of Louisville, Louisville, Kentucky, United States of America
| | - Jon M. Maguire
- UofL Health Brown Cancer Center, University of Louisville, Louisville, Kentucky, United States of America
| | - Lynn W. DeLeeuw
- UofL Health Brown Cancer Center, University of Louisville, Louisville, Kentucky, United States of America
| | - Jonathan B. Chaires
- UofL Health Brown Cancer Center, University of Louisville, Louisville, Kentucky, United States of America
- Department of Medicine, University of Louisville, Louisville, Kentucky, United States of America
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, Kentucky, United States of America
- * E-mail: (JBC); (JOT)
| | - John O. Trent
- UofL Health Brown Cancer Center, University of Louisville, Louisville, Kentucky, United States of America
- Department of Medicine, University of Louisville, Louisville, Kentucky, United States of America
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, Kentucky, United States of America
- * E-mail: (JBC); (JOT)
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18
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Monsen RC, DeLeeuw LW, Dean W, Gray R, Chakravarthy S, Hopkins J, Chaires J, Trent J. Long promoter sequences form higher-order G-quadruplexes: an integrative structural biology study of c-Myc, k-Ras and c-Kit promoter sequences. Nucleic Acids Res 2022; 50:4127-4147. [PMID: 35325198 PMCID: PMC9023277 DOI: 10.1093/nar/gkac182] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 03/03/2022] [Accepted: 03/21/2022] [Indexed: 12/15/2022] Open
Abstract
We report on higher-order G-quadruplex structures adopted by long promoter sequences obtained by an iterative integrated structural biology approach. Our approach uses quantitative biophysical tools (analytical ultracentrifugation, small-angle X-ray scattering, and circular dichroism spectroscopy) combined with modeling and molecular dynamics simulations, to derive self-consistent structural models. The formal resolution of our approach is 18 angstroms, but in some cases structural features of only a few nucleotides can be discerned. We report here five structures of long (34-70 nt) wild-type sequences selected from three cancer-related promoters: c-Myc, c-Kit and k-Ras. Each sequence studied has a unique structure. Three sequences form structures with two contiguous, stacked, G-quadruplex units. One longer sequence from c-Myc forms a structure with three contiguous stacked quadruplexes. A longer c-Kit sequence forms a quadruplex-hairpin structure. Each structure exhibits interfacial regions between stacked quadruplexes or novel loop geometries that are possible druggable targets. We also report methodological advances in our integrated structural biology approach, which now includes quantitative CD for counting stacked G-tetrads, DNaseI cleavage for hairpin detection and SAXS model refinement. Our results suggest that higher-order quadruplex assemblies may be a common feature within the genome, rather than simple single quadruplex structures.
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Affiliation(s)
- Robert C Monsen
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - Lynn W DeLeeuw
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - William L Dean
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - Robert D Gray
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - Srinivas Chakravarthy
- The Biophysics Collaborative Access Team (BioCAT), Department of Biological, Chemical, and Physical Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Jesse B Hopkins
- The Biophysics Collaborative Access Team (BioCAT), Department of Biological, Chemical, and Physical Sciences, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Jonathan B Chaires
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
- Department of Medicine, University of Louisville, Louisville, KY 40202, USA
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40202, USA
| | - John O Trent
- UofL Health Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
- Department of Medicine, University of Louisville, Louisville, KY 40202, USA
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40202, USA
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19
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Frasson I, Pirota V, Richter SN, Doria F. Multimeric G-quadruplexes: A review on their biological roles and targeting. Int J Biol Macromol 2022; 204:89-102. [PMID: 35124022 DOI: 10.1016/j.ijbiomac.2022.01.197] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 01/20/2022] [Accepted: 01/31/2022] [Indexed: 12/12/2022]
Abstract
In human cells, nucleic acids adopt several non-canonical structures that regulate key cellular processes. Among them, G-quadruplexes (G4s) are stable structures that form in guanine-rich regions in vitro and in cells. G4 folded/unfolded state shapes numerous cellular processes, including genome replication, transcription, and translation. Moreover, G4 folding is involved in genomic instability. G4s have been described to multimerize, forming high-order structures in both DNA and/or RNA strands. Multimeric G4s can be formed by adjacent intramolecular G4s joined by stacking interactions or connected by short loops. Multimeric G4s can also originate from the assembly of guanines embedded on independent DNA or RNA strands. Notably, crucial regions of the human genome, such as the 3'-terminal overhang of the telomeric DNA as well as the open reading frame of genes involved in the preservation of neuron viability in the human central and peripheral nervous system are prone to form multimeric G4s. The biological importance of such structures has been recently described, with multimeric G4s playing potentially protective or deleterious effects in the pathogenic cascade of various diseases. Here, we portray the multifaceted scenario of multimeric G4s, in terms of structural properties, biological roles, and targeting strategies.
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Affiliation(s)
- Ilaria Frasson
- Department of Molecular Medicine, University of Padova, via A. Gabelli 63, 35121 Padova, Italy
| | - Valentina Pirota
- Department of Chemistry, University of Pavia, v. le Taramelli 10, 27100 Pavia, Italy; G4-INTERACT, USERN, v. le Taramelli 10, 27100 Pavia, Italy
| | - Sara N Richter
- Department of Molecular Medicine, University of Padova, via A. Gabelli 63, 35121 Padova, Italy.
| | - Filippo Doria
- Department of Chemistry, University of Pavia, v. le Taramelli 10, 27100 Pavia, Italy.
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20
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Rigo R, Groaz E, Sissi C. Polymorphic and Higher-Order G-Quadruplexes as Possible Transcription Regulators: Novel Perspectives for Future Anticancer Therapeutic Applications. Pharmaceuticals (Basel) 2022; 15:ph15030373. [PMID: 35337170 PMCID: PMC8950063 DOI: 10.3390/ph15030373] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 03/14/2022] [Accepted: 03/15/2022] [Indexed: 02/06/2023] Open
Abstract
In the past two decades, significant efforts have been put into designing small molecules to target selected genomic sites where DNA conformational rearrangements control gene expression. G-rich sequences at oncogene promoters are considered good points of intervention since, under specific environmental conditions, they can fold into non-canonical tetrahelical structures known as G-quadruplexes. However, emerging evidence points to a frequent lack of correlation between small molecule targeting of G-quadruplexes at gene promoters and the expression of the associated protein, which hampers pharmaceutical applications. The wide genomic localization of G-quadruplexes along with their highly polymorphic behavior may account for this scenario, suggesting the need for more focused drug design strategies. Here, we will summarize the G4 structural features that can be considered to fulfill this goal. In particular, by comparing a telomeric sequence with the well-characterized G-rich domain of the KIT promoter, we will address how multiple secondary structures might cooperate to control genome architecture at a higher level. If this holds true, the link between drug–DNA complex formation and the associated cellular effects will need to be revisited.
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Affiliation(s)
- Riccardo Rigo
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Marzolo 5, 35131 Padova, Italy; (R.R.); (E.G.)
- CEITEC—Central European Institute of Technology, Masaryk University, Kamenice 753/5, 625 00 Brno, Czech Republic
| | - Elisabetta Groaz
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Marzolo 5, 35131 Padova, Italy; (R.R.); (E.G.)
- KU Leuven, Rega Institute for Medical Research, Medicinal Chemistry, Herestraat 49-Box 1041, 3000 Leuven, Belgium
| | - Claudia Sissi
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Marzolo 5, 35131 Padova, Italy; (R.R.); (E.G.)
- Correspondence:
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21
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Ceschi S, Berselli M, Cozzaglio M, Giantin M, Toppo S, Spolaore B, Sissi C. Vimentin binds to G-quadruplex repeats found at telomeres and gene promoters. Nucleic Acids Res 2022; 50:1370-1381. [PMID: 35100428 PMCID: PMC8860586 DOI: 10.1093/nar/gkab1274] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 11/22/2021] [Accepted: 01/24/2022] [Indexed: 11/15/2022] Open
Abstract
G-quadruplex (G4) structures that can form at guanine-rich genomic sites, including telomeres and gene promoters, are actively involved in genome maintenance, replication, and transcription, through finely tuned interactions with protein networks. In the present study, we identified the intermediate filament protein Vimentin as a binder with nanomolar affinity for those G-rich sequences that give rise to at least two adjacent G4 units, named G4 repeats. This interaction is supported by the N-terminal domains of soluble Vimentin tetramers. The selectivity of Vimentin for G4 repeats versus individual G4s provides an unprecedented result. Based on GO enrichment analysis performed on genes having putative G4 repeats within their core promoters, we suggest that Vimentin recruitment at these sites may contribute to the regulation of gene expression during cell development and migration, possibly by reshaping the local higher-order genome topology, as already reported for lamin B.
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Affiliation(s)
- Silvia Ceschi
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova 35131, Italy
| | - Michele Berselli
- Department of Molecular Medicine, University of Padova, Padova 35131, Italy
| | - Marta Cozzaglio
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova 35131, Italy
| | - Mery Giantin
- Department of Comparative Biomedicine and Food Science, University of Padova, Legnaro 35020, Italy
| | - Stefano Toppo
- CRIBI Biotechnology Center (Centro di Ricerca Interdipartimentale per le Biotecnologie Innovative), University of Padova, Padova 35131, Italy
- Department of Molecular Medicine, University of Padova, Padova 35131, Italy
| | - Barbara Spolaore
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova 35131, Italy
- CRIBI Biotechnology Center (Centro di Ricerca Interdipartimentale per le Biotecnologie Innovative), University of Padova, Padova 35131, Italy
| | - Claudia Sissi
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova 35131, Italy
- CRIBI Biotechnology Center (Centro di Ricerca Interdipartimentale per le Biotecnologie Innovative), University of Padova, Padova 35131, Italy
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22
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Libera V, Andreeva EA, Martel A, Thureau A, Longo M, Petrillo C, Paciaroni A, Schirò G, Comez L. Porphyrin Binding and Irradiation Promote G-Quadruplex DNA Dimeric Structure. J Phys Chem Lett 2021; 12:8096-8102. [PMID: 34406777 DOI: 10.1021/acs.jpclett.1c01840] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Nucleic acid sequences rich in guanines can organize into noncanonical DNA G-quadruplexes (G4s) of variable size. The design of small molecules stabilizing the structure of G4s is a rapidly growing area for the development of novel anticancer therapeutic strategies and bottom-up nanotechnologies. Among a multitude of binders, porphyrins are very attractive due to their light activation that can make them valuable conformational regulators of G4s. Here, a structure-based strategy, integrating complementary probes, is employed to study the interaction between TMPyP4 porphyrin and a 22-base human telomeric sequence (Tel22) before and after irradiation with blue light. Porphyrin binding is discovered to promote Tel22 dimerization, while light irradiation of the Tel22-TMPyP4 complex controls dimer fraction. Such a change in quaternary structure is found to be strictly correlated with modifications at the secondary structure level, thus providing an unprecedented link between the degree of dimerization and the underlying conformational changes in G4s.
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Affiliation(s)
- Valeria Libera
- Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, 06123 Perugia, Italy
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
- CNR-IOM c/o Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, 06123 Perugia, Italy
| | - Elena A Andreeva
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, F-38000 Grenoble, France
| | - Anne Martel
- Institut Laue-Langevin, 71 avenue des Martyrs, 38042 Grenoble Cedex 9, France
| | - Aurelien Thureau
- Swing Beamline, Synchrotron SOLEIL, 91192 Gif sur Yvette, France
| | - Marialucia Longo
- Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Lichtenbergstraße 1, 85748 Garching, Germany
| | - Caterina Petrillo
- Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, 06123 Perugia, Italy
| | - Alessandro Paciaroni
- Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, 06123 Perugia, Italy
| | - Giorgio Schirò
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, F-38000 Grenoble, France
| | - Lucia Comez
- CNR-IOM c/o Dipartimento di Fisica e Geologia, Università di Perugia, Via Pascoli, 06123 Perugia, Italy
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23
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Hagihara M. Inhibition of protein synthesis through RNA-based tandem G-quadruplex formation. Chem Commun (Camb) 2021; 57:8063-8066. [PMID: 34296230 DOI: 10.1039/d1cc02995a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
We demonstrate that an RNA template containing eight GGG repeat sequences exhibits a unique tandem G-quadruplex structure in which two individual G-quadruplexes are aligned in close proximity. Because of their unexpected stability, tandem G-quadruplexes formed in the coding region of mRNA strands effectively inhibited in vitro protein synthesis.
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Affiliation(s)
- Masaki Hagihara
- Graduate School of Science and Technology, Hirosaki University, Hirosaki 036-8561, Japan.
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24
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Alessandrini I, Recagni M, Zaffaroni N, Folini M. On the Road to Fight Cancer: The Potential of G-quadruplex Ligands as Novel Therapeutic Agents. Int J Mol Sci 2021; 22:5947. [PMID: 34073075 PMCID: PMC8198608 DOI: 10.3390/ijms22115947] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 05/27/2021] [Accepted: 05/27/2021] [Indexed: 12/14/2022] Open
Abstract
Nucleic acid sequences able to adopt a G-quadruplex conformation are overrepresented within the human genome. This evidence strongly suggests that these genomic regions have been evolutionary selected to play a pivotal role in several aspects of cell biology. In the present review article, we provide an overview on the biological impact of targeting G-quadruplexes in cancer. A variety of small molecules showing good G-quadruplex stabilizing properties has been reported to exert an antitumor activity in several preclinical models of human cancers. Moreover, promiscuous binders and multiple targeting G-quadruplex ligands, cancer cell defense responses and synthetic lethal interactions of G-quadruplex targeting have been also highlighted. Overall, evidence gathered thus far indicates that targeting G-quadruplex may represent an innovative and fascinating therapeutic approach for cancer. The continued methodological improvements, the development of specific tools and a careful consideration of the experimental settings in living systems will be useful to deepen our knowledge of G-quadruplex biology in cancer, to better define their role as therapeutic targets and to help design and develop novel and reliable G-quadruplex-based anticancer strategies.
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Affiliation(s)
| | | | | | - Marco Folini
- Molecular Pharmacology Unit, Department of Applied Research and Technological Development, Fondazione IRCCS Istituto Nazionale dei Tumori di Milano, Via G.A. Amadeo 42, 20133 Milan, Italy; (I.A.); (M.R.); (N.Z.)
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