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Kageler L, Aquilanti E. Discovery of telomerase inhibitors: existing strategies and emerging innovations. Biochem Soc Trans 2024; 52:1957-1968. [PMID: 39194999 DOI: 10.1042/bst20230264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 08/05/2024] [Accepted: 08/06/2024] [Indexed: 08/29/2024]
Abstract
Telomerase, crucial for maintaining telomere length, is an attractive target for cancer therapy due to its role in cellular immortality. Despite three decades of research efforts, no small-molecule telomerase inhibitors have been clinically approved, highlighting the extensive challenges in developing effective telomerase-based therapeutics. This review examines conventional and emerging methods to measure telomerase activity and discusses existing inhibitors, including oligonucleotides and small molecules. Furthermore, this review highlights recent breakthroughs in structural studies of telomerase using cryo-electron microscopy, which can facilitate improved structure-based drug design. Altogether, advancements in structural methodologies and high-throughput screening offer promising prospects for telomerase-based cancer therapeutic development.
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Affiliation(s)
- Lauren Kageler
- Stem Cell Program and Division of Hematology/Oncology, Boston Children's Hospital, Boston, MA, U.S.A
| | - Elisa Aquilanti
- Division of Neuro Oncology, Dana Farber Cancer Institute, Boston, MA, U.S.A
- Department of Medical Oncology, Dana Farber Cancer Institute, Boston, MA, U.S.A
- Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA, U.S.A
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2
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Dey A, Anand K, Singh A, Prasad R, Barthwal R. MOSR and NDHA Genes Comprising G-Quadruplex as Promising Therapeutic Targets against Mycobacterium tuberculosis: Molecular Recognition by Mitoxantrone Suppresses Replication and Gene Regulation. Genes (Basel) 2023; 14:978. [PMID: 37239338 PMCID: PMC10217741 DOI: 10.3390/genes14050978] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/19/2022] [Accepted: 04/18/2023] [Indexed: 05/28/2023] Open
Abstract
Occurrence of non-canonical G-quadruplex (G4) DNA structures in the genome have been recognized as key factors in gene regulation and several other cellular processes. The mosR and ndhA genes involved in pathways of oxidation sensing regulation and ATP generation, respectively, make Mycobacterium tuberculosis (Mtb) bacteria responsible for oxidative stress inside host macrophage cells. Circular Dichroism spectra demonstrate stable hybrid G4 DNA conformations of mosR/ndhA DNA sequences. Real-time binding of mitoxantrone to G4 DNA with an affinity constant ~105-107 M-1, leads to hypochromism with a red shift of ~18 nm, followed by hyperchromism in the absorption spectra. The corresponding fluorescence is quenched with a red shift ~15 nm followed by an increase in intensity. A change in conformation of the G4 DNA accompanies the formation of multiple stoichiometric complexes with a dual binding mode. The external binding of mitoxantrone with a partial stacking with G-quartets and/or groove binding induces significant thermal stabilization, ~20-29 °C in ndhA/mosR G4 DNA. The interaction leads to a two/four-fold downregulation of transcriptomes of mosR/ndhA genes apart from the suppression of DNA replication by Taq polymerase enzyme, establishing the role of mitoxantrone in targeting G4 DNA, as an alternate strategy for effective anti-tuberculosis action in view of deadly multi-drug resistant tuberculosis disease causing bacterial strains t that arise from existing therapeutic treatments.
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Affiliation(s)
- Arpita Dey
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India
| | - Kushi Anand
- Centre for Infectious Disease Research, Indian Institute of Science, Bengaluru 560012, Karnataka, India
| | - Amit Singh
- Centre for Infectious Disease Research, Indian Institute of Science, Bengaluru 560012, Karnataka, India
| | - Ramasare Prasad
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India
| | - Ritu Barthwal
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India
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3
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Binding characterization of anthraquinone derivatives by stabilizing G-quadruplex DNA leads to an anticancerous activity. MOLECULAR THERAPY. NUCLEIC ACIDS 2022; 30:648-662. [PMID: 36514353 PMCID: PMC9720492 DOI: 10.1016/j.omtn.2022.11.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Accepted: 11/11/2022] [Indexed: 11/16/2022]
Abstract
G-quadruplex is a non-canonical secondary structure identified in the telomeric region and the promoter of many oncogenes. Anthraquinone derivatives, a well-known inducer of telomere disruption in malignant cells and activate the apoptotic pathway. We used biophysical and biochemical studies to confirm the interaction of synthesized anthraquinone derivatives with the human telomeric G-quadruplex sequence. The binding affinity of N-2DEA and N-1DEA are K b = 4.8 × 106 M-1 and K b = 7.6 × 105 M-1, respectively, leading to hypochroism, fluorescence quenching with minor redshift and ellipticity variations indicating ligand binding in the external groove. We found that sodium ions induced stabilization more rather than potassium ions. Molecular docking of complex demonstrates a molecule's exterior binding to a quadruplex. The investigation of ROS activity indicated that the cell initiates mortality in response to the IC50 concentration. Cellular morphology, nuclear condensation, and fragmentation were altered in the treated cell, impairing cellular function. Finally, the transcriptional regulatory study paves the way for drug design as an anti-cancer agent because of the tremendous possibilities of changing substituent groups on anthraquinones to improve efficacy and selectivity for G-quartet DNA. Our research focused on how ligand binding to telomere sequences induces oxidative stress and inhibits the growth of malignant cells.
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Dey A, Pandav K, Nath M, Barthwal R, Prasad R. Molecular rec§ognition of telomere DNA sequence by 2, 6 anthraquinone derivatives leads to thermal stabilization and induces apoptosis in cancer cells. Int J Biol Macromol 2022; 221:355-370. [PMID: 36041576 DOI: 10.1016/j.ijbiomac.2022.08.156] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 08/21/2022] [Accepted: 08/22/2022] [Indexed: 11/25/2022]
Abstract
According to current research, anti-cancer anthraquinones impact telomere disruption and may interact with G-quadruplex DNA that triggers signaling to apoptosis. The present study represents the biophysical investigation of oxidative stress, late apoptosis, and induced senescence among cancer cells after binding laboratory synthesized piperidine-based anthraquinone derivatives, 2, 6- Bis [(3-piperidino)acetamido)]anthracene-9,10-dione (N1P) and 2, 6-Bis [piperidino)propionamido]anthracene-9,10-dione (N2P), with G-quadruplex DNA. We employed biophysical approaches to explore the interaction of synthetic anthraquinone derivatives with quadruplex DNA sequences to influence biological activities in the presence of K+ and Na+ cations. The binding affinity for N2P and N1P are Kb = 5.8 × 106 M-1 and Kb = 1.0 × 106 M-1, respectively, leading to hypo-/hyper-chromism with 5-7 nm red shift and significant fluorescence quenching and changes in ellipticity resulting in external binding of both the ligands to G-quadruplex DNA. Ligand binding induced enhancement of thermostability of G4 DNA is greater in Na+ environment (ΔTm = 34 °C) as compared to that in K+ environment (ΔTm = 21 °C), thereby restricting telomerase binding access to telomeres. Microscopic images of treated cells indicated cellular shape, nuclear condensation, and fragmentation alterations. The findings pave the path for therapeutic research, given the great potential of modifying anthraquinone substituent groups towards improved efficacy, ROS generation, and G-quadruplex DNA selectivity.
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Affiliation(s)
- Arpita Dey
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India
| | - Kumud Pandav
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India
| | - Mala Nath
- Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India
| | - Ritu Barthwal
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India.
| | - Ramasare Prasad
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667, India.
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Monteiro AR, Ramos CIV, Lourenço LMO, Fateixa S, Rodrigues J, Neves MGPMS, Trindade T. Interfacial assembly of zinc(II) phthalocyanines on graphene oxide (GO): Stable "turn-off-on" nanoplatforms to detect G-quadruplexes (G4). J Colloid Interface Sci 2022; 627:900-912. [PMID: 35901569 DOI: 10.1016/j.jcis.2022.07.075] [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: 03/25/2022] [Revised: 06/29/2022] [Accepted: 07/12/2022] [Indexed: 10/17/2022]
Abstract
HYPOTHESIS The aggregation of phthalocyanines (Pcs) enfeebles their suitability as G-quadruplex (G4) ligands over time. It is hypothesized that the interfacial assembly of Pcs on graphene oxide (GO) influences intermolecular interactions, thereby affecting their physicochemical properties and inducing stabilization of Pcs in solution. Hence, the stacking of Pcs on GO could be tuned to create nanosystems with the ability to detect G4 for longer periods through a slow release of Pcs. EXPERIMENTS Four cationic structurally-related zinc(II) phthalocyanines (ZnPc) were non-covalently assembled on GO by ultrasonic exfoliation. A comprehensive characterization of ZnPcs@GO was carried out by spectroscopic techniques and electron microscopy to understand the organization of ZnPcs on GO. The fluorescence of ZnPcs@GO was studied in the presence of G4 (T2G5T)4 and duplex ds26 through spectrofluorimetric titrations and monitored along time. FINDINGS GO induced a re-organization of the ZnPcs mostly to J-aggregates and quenched their original fluorescence up to 98 % ("turn-off"). In general, ZnPcs@GO recovered their fluorescence ("turn-on") after the titrations and showed affinity to G4 (KD up to 1.92 μM). This is the first report that highlights the contribution of GO interfaces to assemble ZnPcs and allow their slow and controlled release to detect G4 over longer periods.
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Affiliation(s)
- Ana R Monteiro
- CICECO, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal; LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - Catarina I V Ramos
- LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - Leandro M O Lourenço
- LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - Sara Fateixa
- CICECO, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - Joana Rodrigues
- I3N, Department of Physics, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - Maria G P M S Neves
- LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - Tito Trindade
- CICECO, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
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Trinh KH, Kadam US, Rampogu S, Cho Y, Yang KA, Kang CH, Lee KW, Lee KO, Chung WS, Hong JC. Development of novel fluorescence-based and label-free noncanonical G4-quadruplex-like DNA biosensor for facile, specific, and ultrasensitive detection of fipronil. JOURNAL OF HAZARDOUS MATERIALS 2022; 427:127939. [PMID: 34893377 DOI: 10.1016/j.jhazmat.2021.127939] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 11/23/2021] [Accepted: 11/25/2021] [Indexed: 06/14/2023]
Abstract
Fipronil is a broad-spectrum insecticide widely used in agriculture and residential areas; its indiscriminate use leads to environmental pollution and poses health hazards. Early detection of fipronil is critical to prevent the deleterious effects. However, current insecticide analysis methods such as HPLC, LC/MS, and GC/MS are incompetent; they are costly, immobile, time-consuming, laborious, and need skilled technicians. Hence, a sensitive, specific, and cheap biosensor are essential to containing the contamination. Here, we designed two novel biosensors-the first design relied on fluorescent labeling/quenching, while the second sensor focused on label-free detection using Thioflavin T displacement. Altogether, we identified four candidate aptamers, predicted secondary structures, and performed 3D molecular modeling to predict the binding pocket of fipronil in FiPA6B aptamer. Furthermore, the aptameric sensors showed high sensitivity to fipronil of sub-ppb level LOD, attributed to stringent experimental design. The biosensors displayed high specificity against other phenylpyrazole insecticides and demonstrated robust sensitivity for fipronil in real samples like cabbage and cucumber. Notably, to the best of our knowledge, this is the first demonstration of noncanonical G4-quadruplex-like aptamer binding to fipronil, verified using CD spectroscopy. Such aptasensors possess considerable potential for real-time measurements of hazardous insecticides as point-of-care technology.
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Affiliation(s)
- Kien Hong Trinh
- Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, Gyeongnam 52828, Republic of Korea; Division of Life Science and Division of Applied Life Science (BK21 Four), Gyeongsang National University, Jinju, Gyeongnam 52828, Republic of Korea; Faculty of Biotechnology, Vietnam National University of Agriculture, Hanoi City 12400, Vietnam
| | - Ulhas Sopanrao Kadam
- Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, Gyeongnam 52828, Republic of Korea; Division of Life Science and Division of Applied Life Science (BK21 Four), Gyeongsang National University, Jinju, Gyeongnam 52828, Republic of Korea
| | - Shailima Rampogu
- Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, Gyeongnam 52828, Republic of Korea; Division of Life Science and Division of Applied Life Science (BK21 Four), Gyeongsang National University, Jinju, Gyeongnam 52828, Republic of Korea
| | - Yuhan Cho
- Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, Gyeongnam 52828, Republic of Korea; Division of Life Science and Division of Applied Life Science (BK21 Four), Gyeongsang National University, Jinju, Gyeongnam 52828, Republic of Korea
| | - Kyung-Ae Yang
- Department of Medicine, Columbia University, New York, NY 10032, USA
| | - Chang Ho Kang
- Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, Gyeongnam 52828, Republic of Korea; Division of Life Science and Division of Applied Life Science (BK21 Four), Gyeongsang National University, Jinju, Gyeongnam 52828, Republic of Korea
| | - Keun-Woo Lee
- Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, Gyeongnam 52828, Republic of Korea; Division of Life Science and Division of Applied Life Science (BK21 Four), Gyeongsang National University, Jinju, Gyeongnam 52828, Republic of Korea
| | - Kyun Oh Lee
- Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, Gyeongnam 52828, Republic of Korea; Division of Life Science and Division of Applied Life Science (BK21 Four), Gyeongsang National University, Jinju, Gyeongnam 52828, Republic of Korea
| | - Woo Sik Chung
- Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, Gyeongnam 52828, Republic of Korea; Division of Life Science and Division of Applied Life Science (BK21 Four), Gyeongsang National University, Jinju, Gyeongnam 52828, Republic of Korea
| | - Jong Chan Hong
- Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju, Gyeongnam 52828, Republic of Korea; Division of Life Science and Division of Applied Life Science (BK21 Four), Gyeongsang National University, Jinju, Gyeongnam 52828, Republic of Korea; Division of Plant Sciences, University of Missouri, Columbia, Missouri, MO 65211, USA.
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Barthwal R, Raje S, Pandav K. Structural basis for stabilization of human telomeric G-quadruplex [d-(TTAGGGT)] 4 by anticancer drug epirubicin. Bioorg Med Chem 2020; 28:115761. [PMID: 32992248 DOI: 10.1016/j.bmc.2020.115761] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 08/25/2020] [Accepted: 09/06/2020] [Indexed: 02/07/2023]
Abstract
Anthracycline anticancer drugs show multiple strategies of action on gene functioning by regulation of telomerase enzyme by apoptotic factors, e.g. ceramide level, p53 activity, bcl-2 protein levels, besides inhibiting DNA/RNA synthesis and topoisomerase-II action. We report binding of epirubicin with G-quadruplex (G4) DNA, [d-(TTAGGGT)]4, comprising human telomeric DNA sequence TTAGGG, using 1H and 31P NMR spectroscopy. Diffusion ordered spectroscopy, sequence selective changes in chemical shift (~0.33 ppm) and line broadening in DNA signals suggest formation of a well-defined complex. Presence of sequential nuclear Overhauser enhancements at all base quartet steps and absence of large downfield shifts in 31P resonances preclude intercalative mode of interaction. Restrained molecular dynamics simulations using AMBER force field incorporating intermolecular drug to DNA interproton distances, involving ring D protons of epirubicin depict external binding close to T1-T2-A3 and G6pT7 sites. Binding induced thermal stabilization of G4 DNA (~36 °C), obtained from imino protons and differential scanning calorimetry, is likely to come in the way of telomerase association with telomeres. The findings pave the way for drug-designing with modifications at ring D and daunosamine sugar.
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Affiliation(s)
- Ritu Barthwal
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, India.
| | - Shailja Raje
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, India
| | - Kumud Pandav
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, India
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Barthwal R, Raje S, Pandav K. Structural basis for stabilization of human telomeric G-quadruplex [d-(TTAGGGT)] 4 by anticancer drug adriamycin. J Biomol Struct Dyn 2020; 39:795-815. [PMID: 32070245 DOI: 10.1080/07391102.2020.1730969] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Besides inhibiting DNA duplication, DNA dependent RNA synthesis and topoisomerase-II enzyme action, anticancer drug adriamycin is found to cause telomere dysfunction and shows multiple strategies of action on gene functioning. We present evidence of binding of adriamycin to parallel stranded intermolecular [d-(TTAGGGT)]4 G-quadruplex DNA comprising human telomeric DNA by proton and phosphorus-31 nuclear magnetic resonance spectroscopy. Diffusion ordered spectroscopy shows formation of complex between the two molecules. Changes in chemical shift and line broadening of DNA and adriamycin protons suggest participation of specific chemical groups/moieties in interaction. Presence of sequential nuclear Overhauser enhancements at all base quartet steps and absence of large downfield shifts in 31P resonances give clear proof of absence of intercalation of adriamycin chromophore between base quartets. Restrained molecular dynamics simulations using observed 15 short intermolecular inter proton distance contacts depict stacking of ring D of adriamycin with terminal G6 quartet by displacing T7 base and external groove binding close to T1-T2-A3 bases. The disappearance of imino protons monitored as a function of temperature and differential scanning calorimetry experiments yield thermal stabilization of 24 °C, which is likely to come in the way of telomerase association with telomeres. The findings pave the way for design of alternate anthracycline based drugs with specific modifications at ring D to enhance induced thermal stabilization and use alternate mechanism of binding to G-quadruplex DNA for interference in functional pathway of telomere maintenance by telomerase enzyme besides their well known action on duplex DNA. Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Ritu Barthwal
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, India
| | - Shailja Raje
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, India
| | - Kumud Pandav
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, India
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Raje S, Pandav K, Barthwal R. Binding of anticancer drug adriamycin to parallel G‐quadruplex DNA [d‐(TTAGGGT)]
4
comprising human telomeric DNA leads to thermal stabilization: A multiple spectroscopy study. J Mol Recognit 2019; 33:e2815. [DOI: 10.1002/jmr.2815] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 08/31/2019] [Accepted: 09/03/2019] [Indexed: 12/23/2022]
Affiliation(s)
- Shailja Raje
- Department of BiotechnologyIndian Institute of Technology Roorkee Roorkee India
| | - Kumud Pandav
- Department of BiotechnologyIndian Institute of Technology Roorkee Roorkee India
| | - Ritu Barthwal
- Department of BiotechnologyIndian Institute of Technology Roorkee Roorkee India
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10
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Raje S, Pandav K, Barthwal R. Dual mode of binding of anti cancer drug epirubicin to G-quadruplex [d-(TTAGGGT)] 4 containing human telomeric DNA sequence induces thermal stabilization. Bioorg Med Chem 2019; 27:115131. [PMID: 31685331 DOI: 10.1016/j.bmc.2019.115131] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 09/08/2019] [Accepted: 09/19/2019] [Indexed: 12/16/2022]
Abstract
Epirubicin exerts its anti cancer action by blocking DNA/RNA synthesis and inhibition of topoisomerase-II enzyme. Recent reports on its influence on telomere maintenance, suggest interaction with G-quadruplex DNA leading to multiple strategies of action. The binding of epirubicin with parallel stranded inter molecular G-quadruplex DNA [d-(TTAGGGT)]4 comprising human telomeric DNA sequence TTAGGG was investigated by absorption, fluorescence, circular dichroism and nuclear magnetic resonance spectroscopy. The epirubicin binds as monomer to G-quadruplex DNA with affinity, Kb1 = 3.8 × 106 M-1 and Kb2 = 2.7 × 106 M-1, at two independent sites externally. The specific interactions induce thermal stabilization of DNA by 13.2-26.3 °C, which is likely to come in the way of telomere association with telomerase enzyme and contribute to epirubicin-induced apoptosis in cancer cell lines. The findings pave the way for drug designing in view of the possibility of altering substituent groups on anthracyclines to enhance efficacy using alternate mechanism of its interaction with G4 DNA, causing interference in telomere maintenance pathway by inducing telomere dysfunction.
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Affiliation(s)
- Shailja Raje
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, India
| | - Kumud Pandav
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, India
| | - Ritu Barthwal
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, India.
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11
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Raje S, Barthwal R. Molecular recognition of 3+1 hybrid human telomeric G-quadruplex DNA d-[AGGG(TTAGGG) 3] by anticancer drugs epirubicin and adriamycin leads to thermal stabilization. Int J Biol Macromol 2019; 139:1272-1287. [PMID: 31421170 DOI: 10.1016/j.ijbiomac.2019.08.109] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 08/12/2019] [Accepted: 08/12/2019] [Indexed: 11/30/2022]
Abstract
Recent reports suggest influence of anti-cancer anthracyclines on telomere dysfunction and their possible interaction with G-quadruplex (G4) DNA as an alternate pathway to apoptosis. We have investigated interaction of epirubicin and adriamycin with G4 DNA [d-AGGG(TTAGGG)3] comprising human telomeric DNA sequence by surface plasmon resonance, absorption, fluorescence, circular dichroism and thermal denaturation. Epirubicin and adriamycin bind with affinity, Kb, = 2.5×105 and 5.2×105M-1, respectively in monomeric form leading to decrease in absorbance, fluorescence quenching and ellipticity changes without any significant shift in absorption emission maxima with corresponding induced thermal stabilization by 13.0 and 11.6°C in K+ rich solution. Na+ ions did not induce any thermal stabilization. Molecular docking confirmed external binding at grooves and loops of G4 DNA involving 4OCH3 of ring D, 9COCH2OH of ring A, 4'OH/H and 3'NH3+ of daunosamine sugar. Thermal stabilization induced by specific interactions is likely to hamper telomere association with telomerase enzyme and contribute to drug-induced apoptosis in cancer cell lines besides causing damage to duplex DNA. The findings pave the way for drug designing in view of immense possibilities of altering substituent groups on anthracyclines for enhancement of efficacy, reduced cell toxicity as well as specificity towards G-quadruplex DNA.
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Affiliation(s)
- Shailja Raje
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, India
| | - Ritu Barthwal
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee 247667, India.
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Todorov G, Cunha C. Hypothesis: Regulation of neuroplasticity may involve I-motif and G-quadruplex DNA formation modulated by epigenetic mechanisms. Med Hypotheses 2019; 127:129-135. [PMID: 31088636 DOI: 10.1016/j.mehy.2019.04.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 04/04/2019] [Accepted: 04/08/2019] [Indexed: 01/12/2023]
Abstract
Recent studies demonstrated the existence in vivo of various functional DNA structures that differ from the double helix. The G-quadruplex (G4) and intercalated motif (I-motif or IM) DNA structures are formed as knots where, correspondingly, guanines or cytosines on the same strand of DNA bind to each other. There are grounds to believe that G4 and IM sequences play a significant role in regulating gene expression considering their tendency to be found in or near regulatory sites (such as promoters, enhancers, and telomeres) as well as the correlation between the prevalence of G4 or IM conformations and specific phases of cell cycle. Notably, G4 and IM capable sequences tend to be found on the opposite strands of the same DNA site with at most one of the two structures formed at any given time. The recent evidence that K+, Mg2+ concentrations directly affect IM formation (and likely G4 formation indirectly) lead us to believe that these structures may play a major role in synaptic plasticity of neurons, and, therefore, in a variety of central nervous system (CNS) functions including memory, learning, habitual behaviors, pain perception and others. Furthermore, epigenetic mechanisms, which have an important role in synaptic plasticity and memory formation, were also shown to influence formation and stability of G4s and IMs. Our hypothesis is that non-canonical DNA and RNA structures could be an integral part of neuroplasticity control via gene expression regulation at the level of transcription, translation and splicing. We propose that the regulatory activity of DNA IM and G4 structures is modulated by DNA methylation/demethylation of the IM and/or G4 sequences, which facilitates the switch between canonical and non-canonical conformation. Other neuronal mechanisms interacting with the formation and regulatory activity of non-canonical DNA and RNA structures, particularly G4, IM and triplexes, may involve microRNAs as well as ion and proton fluxes. We are proposing experiments in acute brain slices and in vivo to test our hypothesis. The proposed studies would provide new insights into fundamental neuronal mechanisms in health and disease and potentially open new avenues for treating mental health disorders.
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Affiliation(s)
- German Todorov
- Emotional Brain Institute, Nathan Kline Institute, Orangeburg, NY, USA
| | - Catarina Cunha
- Emotional Brain Institute, Nathan Kline Institute, Orangeburg, NY, USA.
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Wu G, Chen L, Liu W, Yang D. Molecular Recognition of the Hybrid-Type G-Quadruplexes in Human Telomeres. Molecules 2019; 24:molecules24081578. [PMID: 31013622 PMCID: PMC6514847 DOI: 10.3390/molecules24081578] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Revised: 04/17/2019] [Accepted: 04/19/2019] [Indexed: 12/13/2022] Open
Abstract
G-quadruplex (G4) DNA secondary structures formed in human telomeres have been shown to inhibit cancer-specific telomerase and alternative lengthening of telomere (ALT) pathways. Thus, human telomeric G-quadruplexes are considered attractive targets for anticancer drugs. Human telomeric G-quadruplexes are structurally polymorphic and predominantly form two hybrid-type G-quadruplexes, namely hybrid-1 and hybrid-2, under physiologically relevant solution conditions. To date, only a handful solution structures are available for drug complexes of human telomeric G-quadruplexes. In this review, we will describe two recent solution structural studies from our labs. We use NMR spectroscopy to elucidate the solution structure of a 1:1 complex between a small molecule epiberberine and the hybrid-2 telomeric G-quadruplex, and the structures of 1:1 and 4:2 complexes between a small molecule Pt-tripod and the hybrid-1 telomeric G-quadruplex. Structural information of small molecule complexes can provide important information for understanding small molecule recognition of human telomeric G-quadruplexes and for structure-based rational drug design targeting human telomeric G-quadruplexes.
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Affiliation(s)
- Guanhui Wu
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, 575 W Stadium Ave, West Lafayette, IN 47907, USA.
| | - Luying Chen
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, 575 W Stadium Ave, West Lafayette, IN 47907, USA.
| | - Wenting Liu
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, 575 W Stadium Ave, West Lafayette, IN 47907, USA.
| | - Danzhou Yang
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, 575 W Stadium Ave, West Lafayette, IN 47907, USA.
- Purdue Center for Cancer Research, 201 S University St, West Lafayette, IN 47906, USA.
- Purdue Institute for Drug Discovery, 720 Clinic Dr, West Lafayette, IN 47907, USA.
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Parasitic Protozoa: Unusual Roles for G-Quadruplexes in Early-Diverging Eukaryotes. Molecules 2019; 24:molecules24071339. [PMID: 30959737 PMCID: PMC6480360 DOI: 10.3390/molecules24071339] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 04/02/2019] [Accepted: 04/03/2019] [Indexed: 12/17/2022] Open
Abstract
Guanine-quadruplex (G4) motifs, at both the DNA and RNA levels, have assumed an important place in our understanding of the biology of eukaryotes, bacteria and viruses. However, it is generally little known that their very first description, as well as the foundational work on G4s, was performed on protozoans: unicellular life forms that are often parasitic. In this review, we provide a historical perspective on the discovery of G4s, intertwined with their biological significance across the protozoan kingdom. This is a history in three parts: first, a period of discovery including the first characterisation of a G4 motif at the DNA level in ciliates (environmental protozoa); second, a period less dense in publications concerning protozoa, during which DNA G4s were discovered in both humans and viruses; and third, a period of renewed interest in protozoa, including more mechanistic work in ciliates but also in pathogenic protozoa. This last period has opened an exciting prospect of finding new anti-parasitic drugs to interfere with parasite biology, thus adding new compounds to the therapeutic arsenal.
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