1
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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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2
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Grün JT, Schwalbe H. Folding dynamics of polymorphic G-quadruplex structures. Biopolymers 2021; 113:e23477. [PMID: 34664713 DOI: 10.1002/bip.23477] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 09/30/2021] [Accepted: 09/30/2021] [Indexed: 12/14/2022]
Abstract
G-quadruplexes (G4), found in numerous places within the human genome, are involved in essential processes of cell regulation. Chromosomal DNA G4s are involved for example, in replication and transcription as first steps of gene expression. Hence, they influence a plethora of downstream processes. G4s possess an intricate structure that differs from canonical B-form DNA. Identical DNA G4 sequences can adopt multiple long-lived conformations, a phenomenon known as G4 polymorphism. A detailed understanding of the molecular mechanisms that drive G4 folding is essential to understand their ambivalent regulatory roles. Disentangling the inherent dynamic and polymorphic nature of G4 structures thus is key to unravel their biological functions and make them amenable as molecular targets in novel therapeutic approaches. We here review recent experimental approaches to monitor G4 folding and discuss structural aspects for possible folding pathways. Substantial progress in the understanding of G4 folding within the recent years now allows drawing comprehensive models of the complex folding energy landscape of G4s that we herein evaluate based on computational and experimental evidence.
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Affiliation(s)
- J Tassilo Grün
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Harald Schwalbe
- Institute for Organic Chemistry and Chemical Biology, Johann Wolfgang Goethe-University, Frankfurt/M, Germany.,Center for Biomolecular Magnetic Resonance (BMRZ), Johann Wolfgang Goethe-University Frankfurt, Frankfurt/M, Germany
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3
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Lago S, Nadai M, Ruggiero E, Tassinari M, Marušič M, Tosoni B, Frasson I, Cernilogar FM, Pirota V, Doria F, Plavec J, Schotta G, Richter SN. The MDM2 inducible promoter folds into four-tetrad antiparallel G-quadruplexes targetable to fight malignant liposarcoma. Nucleic Acids Res 2021; 49:847-863. [PMID: 33410915 PMCID: PMC7826256 DOI: 10.1093/nar/gkaa1273] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 12/18/2020] [Accepted: 12/21/2020] [Indexed: 02/06/2023] Open
Abstract
Well-differentiated liposarcoma (WDLPS) is a malignant neoplasia hard to diagnose and treat. Its main molecular signature is amplification of the MDM2-containing genomic region. The MDM2 oncogene is the master regulator of p53: its overexpression enhances p53 degradation and inhibits apoptosis, leading to the tumoral phenotype. Here, we show that the MDM2 inducible promoter G-rich region folds into stable G-quadruplexes both in vitro and in vivo and it is specifically recognized by cellular helicases. Cell treatment with G-quadruplex-ligands reduces MDM2 expression and p53 degradation, thus stimulating cancer cell cycle arrest and apoptosis. Structural characterization of the MDM2 G-quadruplex revealed an extraordinarily stable, unique four-tetrad antiparallel dynamic conformation, amenable to selective targeting. These data indicate the feasibility of an out-of-the-box G-quadruplex-targeting approach to defeat WDLPS and all tumours where restoration of wild-type p53 is sought. They also point to G-quadruplex-dependent genomic instability as possible cause of MDM2 expansion and WDLPS tumorigenesis.
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Affiliation(s)
- Sara Lago
- Department of Molecular Medicine, University of Padua, via A. Gabelli 63, 35121 Padua, Italy
| | - Matteo Nadai
- Department of Molecular Medicine, University of Padua, via A. Gabelli 63, 35121 Padua, Italy
| | - Emanuela Ruggiero
- Department of Molecular Medicine, University of Padua, via A. Gabelli 63, 35121 Padua, Italy
| | - Martina Tassinari
- Department of Molecular Medicine, University of Padua, via A. Gabelli 63, 35121 Padua, Italy
| | - Maja Marušič
- Slovenian NMR center, National Institute of Chemistry, Hajdrihova, 19, Ljubljana SI-1000, Slovenia
| | - Beatrice Tosoni
- Department of Molecular Medicine, University of Padua, via A. Gabelli 63, 35121 Padua, Italy
| | - Ilaria Frasson
- Department of Molecular Medicine, University of Padua, via A. Gabelli 63, 35121 Padua, Italy
| | - Filippo M Cernilogar
- Division of Molecular Biology, Biomedical Center, Faculty of Medicine, LMU Munich, Germany
| | - Valentina Pirota
- Department of Chemistry, University of Pavia, V. le Taramelli 10, 27100, Pavia, Italy
| | - Filippo Doria
- Department of Chemistry, University of Pavia, V. le Taramelli 10, 27100, Pavia, Italy
| | - Janez Plavec
- Slovenian NMR center, National Institute of Chemistry, Hajdrihova, 19, Ljubljana SI-1000, Slovenia
| | - Gunnar Schotta
- Division of Molecular Biology, Biomedical Center, Faculty of Medicine, LMU Munich, Germany
| | - Sara N Richter
- Department of Molecular Medicine, University of Padua, via A. Gabelli 63, 35121 Padua, Italy
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4
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Vozdova M, Kubickova S, Fictum P, Cernohorska H, Fröhlich J, Rubes J. Mutation and methylation status of KIT and TP 53 in canine cutaneous and subcutaneous mast cell tumours. Vet Comp Oncol 2019; 18:438-444. [PMID: 31574575 DOI: 10.1111/vco.12543] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 09/10/2019] [Accepted: 09/16/2019] [Indexed: 01/08/2023]
Abstract
Cutaneous and subcutaneous mast cell tumours (MCTs) are counted among the most frequent cancers in dogs. However, the genetic aetiology of their development is still mostly unknown, with the exception of KIT and tumor protein p53 (TP53 ) mutations reported in less than a half of cutaneous MCTs. In subcutaneous MCTs, no gene alterations were previously detected. We analysed KIT and TP53 mutations in cutaneous and subcutaneous MCTs, and identified methylated CpG sites in KIT and TP53 promoters and adjacent exon 1 regions. The mutation analysis focused on KIT exons 8, 9 and 11, and TP53 exons 5-8, and revealed mutations in 26% and 7% cutaneous MCT cases, respectively. Moreover, we report a first case of KIT mutation ever detected in subcutaneous MCTs. KIT exon 11 mutations and high Kiupel and Patnaik grades were associated with reduced survival in this study. Both KIT and TP53 gene were generally unmethylated in canine cutaneous MCTs. A sporadic methylation of the CpG positions in KIT promoter and adjacent exon 1 was detected in 70.4% of cutaneous and 82% of subcutaneous MCTs. A sporadic methylation of the CpG positions in the TP53 promoter and exon 1 was observed in 36.8% of the analysed cutaneous MCT samples. Only in two subcutaneous MCTs, we observed more than 30% of clones showing KIT methylation at the CpG positions 13 or 14. The CpG position 14 is involved in a predicted binding site for Sp1 transcription factor. However, the significance of KIT promoter methylation at this specific position needs further evaluation.
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Affiliation(s)
- Miluse Vozdova
- Department of Genetics and Reproduction, Central European Institute of Technology-Veterinary Research Institute, Brno, Czech Republic
| | - Svatava Kubickova
- Department of Genetics and Reproduction, Central European Institute of Technology-Veterinary Research Institute, Brno, Czech Republic
| | - Petr Fictum
- Department of Pathological Morphology and Parasitology, Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Sciences Brno, Brno, Czech Republic
| | - Halina Cernohorska
- Department of Genetics and Reproduction, Central European Institute of Technology-Veterinary Research Institute, Brno, Czech Republic
| | - Jan Fröhlich
- Department of Genetics and Reproduction, Central European Institute of Technology-Veterinary Research Institute, Brno, Czech Republic
| | - Jiri Rubes
- Department of Genetics and Reproduction, Central European Institute of Technology-Veterinary Research Institute, Brno, Czech Republic
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5
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Kotar A, Rigo R, Sissi C, Plavec J. Two-quartet kit* G-quadruplex is formed via double-stranded pre-folded structure. Nucleic Acids Res 2019; 47:2641-2653. [PMID: 30590801 PMCID: PMC6411839 DOI: 10.1093/nar/gky1269] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 11/16/2018] [Accepted: 12/10/2018] [Indexed: 01/13/2023] Open
Abstract
In the promoter of c-KIT proto-oncogene, whose deregulation has been implicated in many cancers, three G-rich regions (kit1, kit* and kit2) are able to fold into G-quadruplexes. While kit1 and kit2 have been studied in depth, little information is available on kit* folding behavior despite its key role in regulation of c-KIT transcription. Notably, kit* contains consensus sites for SP1 and AP2 transcription factors. Herein, a set of complementary spectroscopic and biophysical methods reveals that kit*, d[GGCGAGGAGGGGCGTGGCCGGC], adopts a chair type antiparallel G-quadruplex with two G-quartets at physiological relevant concentrations of KCl. Heterogeneous ensemble of structures is observed in the presence of Na+ and NH4+ ions, which however stabilize pre-folded structure. In the presence of K+ ions stacking interactions of adenine and thymine residues on the top G-quartet contribute to structural stability together with a G10•C18 base pair and a fold-back motif of the five residues at the 3′-terminal under the bottom G-quartet. The 3′-tail enables formation of a bimolecular pre-folded structure that drives folding of kit* into a single G-quadruplex. Intriguingly, kinetics of kit* G-quadruplex formation matches timescale of transcriptional processes and might demonstrate interplay of kinetic and thermodynamic factors for understanding regulation of c-KIT proto-oncogene expression.
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Affiliation(s)
- Anita Kotar
- Slovenian NMR Center, National Institute of Chemistry, 1000 Ljubljana, Slovenia
| | - Riccardo Rigo
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, 35131 Padova, Italy
| | - Claudia Sissi
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, 35131 Padova, Italy
| | - Janez Plavec
- Slovenian NMR Center, National Institute of Chemistry, 1000 Ljubljana, Slovenia.,Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1000 Ljubljana, Slovenia.,EN-FIST Center of Excellence, 1000 Ljubljana, Slovenia
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6
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Whole-Transcriptome Profiling of Canine and Human in Vitro Models Exposed to a G-Quadruplex Binding Small Molecule. Sci Rep 2018; 8:17107. [PMID: 30459395 PMCID: PMC6244004 DOI: 10.1038/s41598-018-35516-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 11/06/2018] [Indexed: 11/24/2022] Open
Abstract
G-quadruplexes (G4) are secondary nucleic acid structures that have been associated with genomic instability and cancer progression. When present in the promoter of some oncogenes, G4 structures can affect gene regulation and, hence, represent a possible therapeutic target. In this study, RNA-Seq was used to explore the effect of a G4-binding anthraquinone derivative, named AQ1, on the whole-transcriptome profiles of two common cell models for the study of KIT pathways; the human mast cell leukemia (HMC1.2) and the canine mast cell tumor (C2). The highest non-cytotoxic dose of AQ1 (2 µM) resulted in 5441 and 1201 differentially expressed genes in the HMC1.2 and C2 cells, respectively. In both cell lines, major pathways such as cell cycle progression, KIT- and MYC-related pathways were negatively enriched in the AQ1-treated group, while other pathways such as p53, apoptosis and hypoxia-related were positively enriched. These findings suggest that AQ1 treatment induces a similar functional response in the human and canine cell models, and provide news insights into using dogs as a reliable translational model for studying G4-binding compounds.
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7
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Zorzan E, Da Ros S, Giantin M, Shahidian LZ, Guerra G, Palumbo M, Sissi C, Dacasto M. Targeting Canine KIT Promoter by Candidate DNA G-Quadruplex Ligands. J Pharmacol Exp Ther 2018; 367:461-472. [PMID: 30275152 DOI: 10.1124/jpet.118.248997] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 09/26/2018] [Indexed: 12/16/2022] Open
Abstract
G-quadruplexes (G4) are nucleic acid secondary structures frequently assumed by G-rich sequences located mostly at telomeres and proto-oncogenes promoters. Recently, we identified, in canine KIT (v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog) promoter, two G-rich sequences able to fold into G4: d_kit1 and d_kit2_A16. In this study, an anthraquinone (AQ1) and an anthracene derivative (AN6), known to stabilize the G4 structures of the corresponding human h_kit1 and h_kit2, were tested on the canine G4 and in two canine mast cell tumor (MCT) cell lines (C2 and NI-1) to verify their capability to down-regulate KIT expression. The cytotoxicity of AQ1 and AN6 was determined using the Alamar Blue test; also the constitutive expression of KIT and other proto-oncogenes containing G4 structures in their promoter (BCL2, VEGFα, VEGFR2, KRAS, and TERT) was assessed by quantitative real-time polymerase chain reaction (qRT-PCR). Then the time- and dose-dependent effects of both ligands on target gene expression were assessed by qRT-PCR. All target genes were constitutively expressed up to 96 hours of culture. Both ligands decreased KIT mRNA levels and c-kit protein amount, and AN6 was comparatively fairly more effective. DNA interaction studies and a dual-luciferase gene reporter assay performed on a noncancerous canine cell line (Madin-Darby Canine Kidney cells) proved that this down-regulation was the result of the interaction of AN6 with KIT proximal promoter. Interestingly, our results only partially overlap with those previously obtained in human cell lines, where AQ1 was found as the most effective compound. These preliminary data might suggest AN6 as a promising candidate for the selective targeting of canine KIT-dependent tumors.
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Affiliation(s)
- Eleonora Zorzan
- Department of Comparative Biomedicine and Food Science, University of Padua, Agripolis Legnaro, Padua, Italy (E.Z., M.G., L.Z.S., G.G., M.D.), and Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Padua, Italy (S.D.R., M.P., C.S.)
| | - Silvia Da Ros
- Department of Comparative Biomedicine and Food Science, University of Padua, Agripolis Legnaro, Padua, Italy (E.Z., M.G., L.Z.S., G.G., M.D.), and Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Padua, Italy (S.D.R., M.P., C.S.)
| | - Mery Giantin
- Department of Comparative Biomedicine and Food Science, University of Padua, Agripolis Legnaro, Padua, Italy (E.Z., M.G., L.Z.S., G.G., M.D.), and Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Padua, Italy (S.D.R., M.P., C.S.)
| | - Lara Zorro Shahidian
- Department of Comparative Biomedicine and Food Science, University of Padua, Agripolis Legnaro, Padua, Italy (E.Z., M.G., L.Z.S., G.G., M.D.), and Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Padua, Italy (S.D.R., M.P., C.S.)
| | - Giorgia Guerra
- Department of Comparative Biomedicine and Food Science, University of Padua, Agripolis Legnaro, Padua, Italy (E.Z., M.G., L.Z.S., G.G., M.D.), and Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Padua, Italy (S.D.R., M.P., C.S.)
| | - Manlio Palumbo
- Department of Comparative Biomedicine and Food Science, University of Padua, Agripolis Legnaro, Padua, Italy (E.Z., M.G., L.Z.S., G.G., M.D.), and Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Padua, Italy (S.D.R., M.P., C.S.)
| | - Claudia Sissi
- Department of Comparative Biomedicine and Food Science, University of Padua, Agripolis Legnaro, Padua, Italy (E.Z., M.G., L.Z.S., G.G., M.D.), and Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Padua, Italy (S.D.R., M.P., C.S.)
| | - Mauro Dacasto
- Department of Comparative Biomedicine and Food Science, University of Padua, Agripolis Legnaro, Padua, Italy (E.Z., M.G., L.Z.S., G.G., M.D.), and Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Padua, Italy (S.D.R., M.P., C.S.)
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8
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Conjunction of G-quadruplex and stem-loop in the 5' untranslated region of mouse hepatocyte nuclear factor 4-alpha1 mediates strong inhibition of protein expression. Mol Cell Biochem 2018; 446:73-81. [PMID: 29332143 DOI: 10.1007/s11010-018-3274-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 01/04/2018] [Indexed: 10/18/2022]
Abstract
Hepatocyte nuclear factor 4-alpha (HNF4α) is a well-established master regulator of liver development and function. Restoration of HNF4α can treat multiple liver disorders and liver cancers. To date, HNF4α is still "undruggable" due to lack of known activating ligands. Thus, understanding the regulatory mechanism of HNF4α expression may help develop an alternative approach to modulate HNF4α protein levels. G-quadruplexes (G4) are non-canonical stable secondary structures discovered mostly in the promoters of oncogenes. Recent genome-wide studies demonstrate the enrichment of G4s in the 5' untranslated region (UTR). By protoporphyrin IX-binding assay and circular dichroism spectrum, we validated the presence of a chemically highly stable 4-ring G4 within the 5' UTR of mouse Hnf4a1. Our real-time PCR and Western blot data showed that the Hnf4a1 5' UTR caused a remarkable translational suppression regardless of a moderate effect on Hnf4a1 mRNA levels. The subsequent deletion/mutation analysis of Hnf4a1 5' UTR using dual-luciferase reporter assays further demonstrated that although the disruption of the chemically highly stable 4-ring G4 resulted in a marked attenuation of inhibition, the G4 alone only weakly inhibited translation. Likewise, disruption of a long stem-loop adjacent to the 4-ring G4 markedly attenuated translational inhibition, although the stem-loop alone only exerted a weak inhibitory effect. Thus, the tight conjunction of G4s and an adjacent stem-loop within the Hnf4a1 5' UTR was both necessary and sufficient to mediate the very strong translational repression. Our results establish a novel working model that a chemically stable G4 may require co-factors to be bio-stable for exerting biological functions.
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9
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Rigo R, Dean WL, Gray RD, Chaires JB, Sissi C. Conformational profiling of a G-rich sequence within the c-KIT promoter. Nucleic Acids Res 2018; 45:13056-13067. [PMID: 29069417 PMCID: PMC5727440 DOI: 10.1093/nar/gkx983] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 10/11/2017] [Indexed: 12/03/2022] Open
Abstract
G-quadruplexes (G4) within oncogene promoters are considered to be promising anticancer targets. However, often they undergo complex structural rearrangements that preclude a precise description of the optimal target. Moreover, even when solved structures are available, they refer to the thermodynamically stable forms but little or no information is supplied about their complex multistep folding pathway. To shed light on this issue, we systematically followed the kinetic behavior of a G-rich sequence located within the c-KIT proximal promoter (kit2) in the presence of monovalent cations K+ and Na+. A very short-lived intermediate was observed to start the G4 folding process in both salt conditions. Subsequently, the two pathways diverge to produce distinct thermodynamically stable species (parallel and antiparallel G-quadruplex in K+ and Na+, respectively). Remarkably, in K+-containing solution a branched pathway is required to drive the wild type sequence to distribute between a monomeric and dimeric G-quadruplex. Our approach has allowed us to identify transient forms whose relative abundance is regulated by the environment; some of them were characterized by a half-life within the timescale of physiological DNA processing events and thus may represent possible unexpected targets for ligands recognition.
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Affiliation(s)
- Riccardo Rigo
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, 35131 Padova, Italy
| | - William L Dean
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - Robert D Gray
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - Jonathan B Chaires
- James Graham Brown Cancer Center, University of Louisville, Louisville, KY 40202, USA
| | - Claudia Sissi
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, 35131 Padova, Italy
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10
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Guo S, Lu H. Conjunction of potential G-quadruplex and adjacent cis-elements in the 5' UTR of hepatocyte nuclear factor 4-alpha strongly inhibit protein expression. Sci Rep 2017; 7:17444. [PMID: 29234104 PMCID: PMC5727235 DOI: 10.1038/s41598-017-17629-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 11/28/2017] [Indexed: 01/11/2023] Open
Abstract
Hepatocyte nuclear factor 4-alpha (HNF4α) is a well established master regulator of liver development and function. We identified the in vitro presence of a stable secondary structure, G-quadruplex (G4) in the 5' UTR of P1-HNF4A, the predominant HNF4α isoform(s) in adult liver. Our data suggest that the cooperation of G4 and the adjacent putative protein-binding sites within the 5' UTR was necessary and sufficient to mediate a strong translational repression. This was supported by analysis of deleted/mutated 5'UTRs and two native regulatory single-nucleotide polymorphisms in the 5'UTR. Additional results indicated that G4 motifs in the 5' UTRs of other liver-enriched transcription factors also inhibited protein expression. Moreover, pyridostatin, a G4 ligand, specifically potentiated the translational suppressing effect of P1-HNF4A-5' UTR. In summary, the present study provides the first evidence of the presence of G4 in human P1-HNF4A-5' UTR in vitro, and establishes a novel working model of strong inhibition of protein translation via interactions of G4 with potential RNA-binding proteins (RBPs). The protein expression of the tumor suppressor HNF4α may be inhibited by interactions of RBPs with the G4 motif in the 5' UTR to promote cell proliferation during liver development and carcinogenesis.
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Affiliation(s)
- Shangdong Guo
- Department of Pharmacology, SUNY Upstate Medical University, Syracuse, NY, 13210, United States
| | - Hong Lu
- Department of Pharmacology, SUNY Upstate Medical University, Syracuse, NY, 13210, United States.
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11
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Rigo R, Sissi C. Characterization of G4-G4 Crosstalk in the c-KIT Promoter Region. Biochemistry 2017; 56:4309-4312. [PMID: 28763217 DOI: 10.1021/acs.biochem.7b00660] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The proximal promoter of c-KIT contains a peculiar domain that consists of three short G-rich sequences that are close together and can fold into noncanonical DNA secondary structures called G-quadruplexes (G4). Here, we focused on a sequence containing two consecutive G4 (kit2 and kit*). By electrophoretic, surface plasmon resonance, and spectroscopic techniques, we demonstrated that they retain the ability to fold into G4 upon being inserted into the extended sequence. Here, we highlighted the occurrence of crosstalk between the two forming units. This previously unexplored G4-G4 interaction modulates both the conformation and the stability of the overall arrangement of the c-KIT promoter. It is not supported by stacking of single nucleotides but refers to a G4-G4 interaction surface surrounded by a two-nucleotides loop that might represent a reliable unprecedented target for anticancer therapy.
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Affiliation(s)
- Riccardo Rigo
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova , Via Marzolo 5, 35131 Padova, Italy
| | - Claudia Sissi
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova , Via Marzolo 5, 35131 Padova, Italy
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12
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Rigo R, Palumbo M, Sissi C. G-quadruplexes in human promoters: A challenge for therapeutic applications. Biochim Biophys Acta Gen Subj 2016; 1861:1399-1413. [PMID: 28025083 DOI: 10.1016/j.bbagen.2016.12.024] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 12/21/2016] [Accepted: 12/22/2016] [Indexed: 12/19/2022]
Abstract
BACKGROUND G-rich sequences undergo unique structural equilibria to form G-quadruplexes (G4) both in vitro and in cell systems. Several pathologies emerged to be directly related to G4 occurrence at defined genomic portions. Additionally, G-rich sequences are significantly represented around transcription start sites (TSS) thus leading to the hypothesis of a gene regulatory function for G4. Thus, the tuning of G4 formation has been proposed as a new powerful tool to regulate gene expression to treat related pathologies. However, up-to date this approach did not provide any new really efficient treatment. SCOPE OF REVIEW Here, we summarize the most recent advances on the correlation between the structural features of G4 in human promoters and the role these systems physiologically exert. In particular we focus on the effect of G4 localization among cell compartments and along the promoters in correlation with protein interaction networks and epigenetic state. Finally the intrinsic structural features of G4 at promoters are discussed to unveil the contribution of different G4 structural modules in this complex architecture. MAJOR CONCLUSIONS It emerges that G4s play several roles in the intriguing and complex mechanism of gene expression, being able to produce opposite effects on the same target. This reflects the occurrence of a highly variegate network of several components working simultaneously. GENERAL SIGNIFICANCE The resulting picture is still fuzzy but some points of strength are definitely emerging, which prompts all of us to strengthen our efforts in view of a selective control of gene expression through G4 modulation. This article is part of a Special Issue entitled "G-quadruplex" Guest Editor: Dr. Concetta Giancola and Dr. Daniela Montesarchio.
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Affiliation(s)
- Riccardo Rigo
- Dept. of Pharmaceutical and Pharmacological Sciences, University of Padova, v. Marzolo, 5, 35131 Padova, Italy
| | - Manlio Palumbo
- Dept. of Pharmaceutical and Pharmacological Sciences, University of Padova, v. Marzolo, 5, 35131 Padova, Italy
| | - Claudia Sissi
- Dept. of Pharmaceutical and Pharmacological Sciences, University of Padova, v. Marzolo, 5, 35131 Padova, Italy.
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Abstract
Quadruplex-forming sequences are widely prevalent in human and other genomes, including bacterial ones. These sequences are over-represented in eukaryotic telomeres, promoters, and 5' untranslated regions. They can form quadruplex structures, which may be transient in many situations in normal cells since they can be effectively resolved by helicase action. Mutated helicases in cancer cells are unable to unwind quadruplexes, which are impediments to transcription, translation, or replication, depending on their location within a particular gene. Small molecules that can stabilize quadruplex structures augment these effects and produce cell and proliferation growth inhibition. This article surveys the chemical biology of quadruplexes. It critically examines the major classes of quadruplex-binding small molecules that have been developed to date and the various approaches to discovering selective agents. The challenges of requiring (and achieving) small-molecule targeted selectivity for a particular quadruplex are discussed in relation to the potential of these small molecules as clinically useful therapeutic agents.
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Affiliation(s)
- Stephen Neidle
- UCL School of Pharmacy, University College London , 29-39 Brunswick Square, London WC1N 1AX, U.K
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14
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Zorzan E, Hanssens K, Giantin M, Dacasto M, Dubreuil P. Mutational Hotspot of TET2, IDH1, IDH2, SRSF2, SF3B1, KRAS, and NRAS from Human Systemic Mastocytosis Are Not Conserved in Canine Mast Cell Tumors. PLoS One 2015; 10:e0142450. [PMID: 26562302 PMCID: PMC4643045 DOI: 10.1371/journal.pone.0142450] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 10/21/2015] [Indexed: 12/11/2022] Open
Abstract
Introduction Both canine cutaneous mast cell tumor (MCT) and human systemic mastocytosis (SM) are characterized by abnormal proliferation and accumulation of mast cells in tissues and, frequently, by the presence of activating mutations in the receptor tyrosine kinase V-Kit Hardy-Zuckerman 4 Feline Sarcoma Viral Oncogene Homolog (c-KIT), albeit at different incidence (>80% in SM and 10–30% in MCT). In the last few years, it has been discovered that additional mutations in other genes belonging to the methylation system, the splicing machinery and cell signaling, contribute, with c-KIT, to SM pathogenesis and/or phenotype. In the present study, the mutational profile of the Tet methylcytosine dioxygenase 2 (TET2), the isocitrate dehydrogenases 1 and 2 (IDH1 and IDH2), the serine/arginine-rich splicing factor 2 (SRSF2), the splicing factor 3b subunit 1 (SF3B1), the Kirsten rat sarcoma viral oncogene homolog (KRAS) and the neuroblastoma RAS viral oncogene homolog (NRAS), commonly mutated in human myeloid malignancies and mastocytosis, was investigated in canine MCTs. Methods Using the Sanger sequencing method, a cohort of 75 DNA samples extracted from MCT biopsies already investigated for c-KIT mutations were screened for the “human-like” hot spot mutations of listed genes. Results No mutations were ever identified except for TET2 even if with low frequency (2.7%). In contrast to what is observed in human TET2 no frame-shift mutations were found in MCT samples. Conclusion Results obtained in this preliminary study are suggestive of a substantial difference between human SM and canine MCT if we consider some target genes known to be involved in the pathogenesis of human SM.
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Affiliation(s)
- Eleonora Zorzan
- Department of Comparative Biomedicine and Food Science, University of Padua, Legnaro, Padua, Italy
| | - Katia Hanssens
- Inserm U1068, Centre de Recherche en Cancérologie de Marseille, Signalisation, Hematopoiesis and Mechanisms of Oncogenesis, Centre de référence des mastocytoses, Institut Paoli Calmettes, CNRS, Aix Marseille Université, Marseille, France
| | - Mery Giantin
- Department of Comparative Biomedicine and Food Science, University of Padua, Legnaro, Padua, Italy
| | - Mauro Dacasto
- Department of Comparative Biomedicine and Food Science, University of Padua, Legnaro, Padua, Italy
| | - Patrice Dubreuil
- Inserm U1068, Centre de Recherche en Cancérologie de Marseille, Signalisation, Hematopoiesis and Mechanisms of Oncogenesis, Centre de référence des mastocytoses, Institut Paoli Calmettes, CNRS, Aix Marseille Université, Marseille, France
- * E-mail:
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15
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Formation and stabilization of the telomeric antiparallel G-quadruplex and inhibition of telomerase by novel benzothioxanthene derivatives with anti-tumor activity. Sci Rep 2015; 5:13693. [PMID: 26329134 PMCID: PMC4557076 DOI: 10.1038/srep13693] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 08/03/2015] [Indexed: 12/20/2022] Open
Abstract
G-quadruplexes formed in telomeric DNA sequences at human chromosome ends can be a novel target for the development of therapeutics for the treatment of cancer patients. Herein, we examined the ability of six novel benzothioxanthene derivatives S1–S6 to induce the formation of and stabilize an antiparallel G-quadruplex by EMSA, UV-melting and CD techniques and the influence of S1–S6 on A549 and SGC7901 cells through real-time cell analysis, wound healing, trap assay methods. Results show that six compounds could differentially induce 26 nt G-rich oligonucleotides to form the G-quadruplex with high selectivity vs C-rich DNA, mutated DNA and double-stranded DNA, stabilize it with high affinity, promote apoptosis and inhibit mobility and telomerase activity of A549 cells and SGC7901 cells. Especially, S1, S3, S4 displayed stronger abilities, of which S3 was the most optimal with the maximum ΔTm value being up to 29.8 °C for G-quadruplex, the minimum IC50 value being 0.53 μM and the maximum cell inhibitory rate being up to 97.2%. This study suggests that this type of compounds that induce the formation of and stabilize the telomeric antiparallel G-quadruplex, and consequently inhibit telomerase activity, leading to cell apoptosis, can be screened for the discovery of novel antitumor therapeutics.
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