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1.
Int J Mol Sci ; 22(19)2021 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-34638964

RESUMO

G-quadruplex existence was proved in cells by using both antibodies and small molecule fluorescent probes. However, the G-quadruplex probes designed thus far are structure- but not conformation-specific. Recently, a core-extended naphthalene diimide (cex-NDI) was designed and found to provide fluorescent signals of markedly different intensities when bound to G-quadruplexes of different conformations or duplexes. Aiming at evaluating how the fluorescence behaviour of this compound is associated with specific binding modes to the different DNA targets, cex-NDI was here studied in its interaction with hybrid G-quadruplex, parallel G-quadruplex, and B-DNA duplex models by biophysical techniques, molecular docking, and biological assays. cex-NDI showed different binding modes associated with different amounts of stacking interactions with the three DNA targets. The preferential binding sites were the groove, outer quartet, or intercalative site of the hybrid G-quadruplex, parallel G-quadruplex, and B-DNA duplex, respectively. Interestingly, our data show that the fluorescence intensity of DNA-bound cex-NDI correlates with the amount of stacking interactions formed by the ligand with each DNA target, thus providing the rationale behind the conformation-sensitive properties of cex-NDI and supporting its use as a fluorescent probe of G-quadruplex structures. Notably, biological assays proved that cex-NDI mainly localizes in the G-quadruplex-rich nuclei of cancer cells.

2.
Biomolecules ; 11(7)2021 07 16.
Artigo em Inglês | MEDLINE | ID: mdl-34356672

RESUMO

In the search for new therapeutic strategies to contrast SARS-CoV-2, we here studied the interaction of polydatin (PD) and resveratrol (RESV)-two natural stilbene polyphenols with manifold, well known biological activities-with Spike, the viral protein essential for virus entry into host cells, and ACE2, the angiotensin-converting enzyme present on the surface of multiple cell types (including respiratory epithelial cells) which is the main host receptor for Spike binding. Molecular Docking simulations evidenced that both compounds can bind Spike, ACE2 and the ACE2:Spike complex with good affinity, although the interaction of PD appears stronger than that of RESV on all the investigated targets. Preliminary biochemical assays revealed a significant inhibitory activity of the ACE2:Spike recognition with a dose-response effect only in the case of PD.


Assuntos
Enzima de Conversão de Angiotensina 2/metabolismo , COVID-19/tratamento farmacológico , Glucosídeos/farmacologia , Resveratrol/farmacologia , SARS-CoV-2/efeitos dos fármacos , Glicoproteína da Espícula de Coronavírus/metabolismo , Estilbenos/farmacologia , COVID-19/metabolismo , Descoberta de Drogas , Medicamentos de Ervas Chinesas/farmacologia , Inibidores Enzimáticos/farmacologia , Interações Hospedeiro-Patógeno/efeitos dos fármacos , Humanos , Simulação de Acoplamento Molecular , Ligação Proteica/efeitos dos fármacos , SARS-CoV-2/metabolismo
3.
Molecules ; 26(12)2021 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-34200901

RESUMO

Peptides and their synthetic analogs are a class of molecules with enormous relevance as therapeutics for their ability to interact with biomacromolecules like nucleic acids and proteins, potentially interfering with biological pathways often involved in the onset and progression of pathologies of high social impact. Nucleobase-bearing peptides (nucleopeptides) and pseudopeptides (PNAs) offer further interesting possibilities related to their nucleobase-decorated nature for diagnostic and therapeutic applications, thanks to their reported ability to target complementary DNA and RNA strands. In addition, these chimeric compounds are endowed with intriguing self-assembling properties, which are at the heart of their investigation as self-replicating materials in prebiotic chemistry, as well as their application as constituents of innovative drug delivery systems and, more generally, as novel nanomaterials to be employed in biomedicine. Herein we describe the properties of nucleopeptides, PNAs and related supramolecular systems, and summarize some of the most relevant applications of these systems.


Assuntos
Nanoestruturas/química , Ácidos Nucleicos Peptídicos/química , Peptídeos/química , Animais , DNA/química , Humanos , Prebióticos , RNA/química
4.
J Med Chem ; 64(7): 3578-3603, 2021 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-33751881

RESUMO

In the context of developing efficient anticancer therapies aimed at eradicating any sort of tumors, G-quadruplexes represent excellent targets. Small molecules able to interact with G-quadruplexes can interfere with cell pathways specific of tumors and common to all cancers. Naphthalene diimides (NDIs) are among the most promising, putative anticancer G-quadruplex-targeting drugs, due to their ability to simultaneously target multiple G-quadruplexes and their strong, selective in vitro and in vivo anticancer activity. Here, all the available biophysical, biological, and structural data concerning NDIs targeting G-quadruplexes were systematically analyzed. Structure-activity correlations were obtained by analyzing biophysical data of their interactions with G-quadruplex targets and control duplex structures, in parallel to biological data concerning the antiproliferative activity of NDIs on cancer and normal cells. In addition, NDI binding modes to G-quadruplexes were discussed in consideration of the structures and properties of NDIs by in-depth analysis of the available structural models of G-quadruplex/NDI complexes.


Assuntos
Antineoplásicos/farmacologia , DNA/metabolismo , Quadruplex G , Naftalimidas/farmacologia , Animais , Antineoplásicos/química , Antineoplásicos/metabolismo , Linhagem Celular Tumoral , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Simulação de Dinâmica Molecular , Estrutura Molecular , Naftalimidas/química , Naftalimidas/metabolismo , Relação Estrutura-Atividade
5.
Curr Med Chem ; 28(24): 5004-5015, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33593247

RESUMO

BACKGROUND: Nucleopeptides are chimeric compounds of biomedical importance carrying DNA nucleobases anchored to peptide backbones with the ascertained capacity to bind nucleic acids. However, their ability to interact with proteins involved in pathologies of social relevance is a feature that still requires investigation. The worrying situation currently observed worldwide for the COVID-19 pandemic urgently requires the research on novel anti-SARSCoV- 2 molecular weapons, whose discovery can be aided by in silico predictive studies. OBJECTIVE: The aim of this work is to explore by spectroscopic methods novel features of a thymine-bearing nucleopeptide based on L-diaminopropanoic acid, including conformational aspects as well as its ability to bind proteins, starting from bovine serum albumin (BSA) as a model protein. Moreover, in consideration of the importance of targeting viral proteins in the current fight against COVID-19, we evaluated in silico the interaction of the nucleopeptide with some of the most relevant coronavirus protein targets. METHODS: First, we investigated via circular dichroism (CD) the conformational behaviour of this thymine-bearing nucleopeptide with temperature: we observed CD spectral changes, particularly passing from 15 to 35 °C. Scanning Electron Microscopy (SEM) analysis of the nucleopeptide was also conducted on nucleopeptide solid samples. Additionally, CD binding and preliminary in silico investigations were performed with BSA as a model protein. Moreover, molecular dockings were run using as targets some of the main SARS-CoV-2 proteins. RESULTS: The temperature-dependent CD behaviour reflected the three-dimensional rearrangement of the nucleopeptide at different temperatures, with higher exposure to the solvent of its chromophores at higher temperatures compared to a more stacked structure at a low temperature. SEM analysis of nucleopeptide samples in the solid-state showed a granular morphology, with a low roughness and some thread structures. Moreover, we found through spectroscopic studies that the modified peptide bound the albumin target by inducing significant changes to the protein secondary structure. CONCLUSION: CD and preliminary in silico studies suggested that the nucleopeptide bound the BSA protein with high affinity according to different binding modes, as testified by binding energy scores lower than -11 kcal/mol. Interestingly, a predictive study performed on 3CLpro and other SARS-CoV-2 protein targets suggested the potential ability of the nucleopeptide to bind with good affinity the main protease of the virus and other relevant targets, including the RNAdependent RNA polymerase, especially when complexed with RNA, the papain-like protease, and the coronavirus helicase at the nucleic acid binding site.


Assuntos
COVID-19 , Pandemias , Dicroísmo Circular , Humanos , Simulação de Acoplamento Molecular , Ligação Proteica , SARS-CoV-2
6.
Pharmacol Ther ; 217: 107649, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-32777331

RESUMO

First studies on thrombin-inhibiting DNA aptamers were reported in 1992, and since then a large number of anticoagulant aptamers has been discovered. TBA - also named HD1, a 15-mer G-quadruplex (G4)-forming oligonucleotide - is the best characterized thrombin binding aptamer, able to specifically recognize the protein exosite I, thus inhibiting the conversion of soluble fibrinogen into insoluble fibrin strands. Unmodified nucleic acid-based aptamers, in general, and TBA in particular, exhibit limited pharmacokinetic properties and are rapidly degraded in vivo by nucleases. In order to improve the biological performance of aptamers, a widely investigated strategy is the introduction of chemical modifications in their backbone at the level of the nucleobases, sugar moieties or phosphodiester linkages. Besides TBA, also other thrombin binding aptamers, able to adopt a well-defined G4 structure, e.g. mixed duplex/quadruplex sequences, as well as homo- and hetero-bivalent constructs, have been identified and optimized. Considering the growing need of new efficient anticoagulant agents associated with the strong therapeutic potential of these thrombin inhibitors, the research on thrombin binding aptamers is still a very hot and intriguing field. Herein, we comprehensively described the state-of-the-art knowledge on the DNA-based aptamers targeting thrombin, especially focusing on the optimized analogues obtained by chemically modifying the oligonucleotide backbone, and their biological performances in therapeutic applications.

7.
Int J Biol Macromol ; 166: 1320-1334, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33166559

RESUMO

To selectively target telomeric G-quadruplex (G4) DNA, monomeric and dimeric naphthalene diimides (NDIs) were investigated as binders of multimeric G4 structures able to discriminate duplex DNA. These NDIs were analysed by the affinity chromatography-based screening G4-CPG (G-quadruplex on Controlled Pore Glass), using the sequence d[AGGG(TTAGGG)7] (tel46), folding into two consecutive G4s, as model of the human telomeric G4 multimer. In parallel, a telomeric G4 monomer (tel26) and a duplex structure (ds27) were used as controls. According to G4-CPG screening, NDI-5 proved to be the best ligand in terms of dimeric G4 vs. duplex DNA selectivity and was analysed by circular dichroism (CD), gel electrophoresis, isothermal titration calorimetry (ITC) and fluorescence spectroscopy in its interactions with tel46. NDI-5 strongly binds and stabilizes tel46 G4, favouring a hybrid folding in K+-containing buffer. Under these conditions, the binding process comprises a first event involving three molecules of NDI-5 and a second one in which other six molecules bind to the DNA. In a metal cation-free system, NDI-5 induces tel46 G4 folding, as indicated by CD and PAGE, favouring an antiparallel structuring. Docking simulations showed that NDI-5 can effectively bind to the pocket between two G4 units, representing a promising ligand for multimeric G4s.


Assuntos
Quadruplex G , Imidas/química , Substâncias Intercalantes/química , Naftalenos/química , Humanos , Simulação de Acoplamento Molecular , Telômero/química
8.
Med Res Rev ; 41(1): 464-506, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33038031

RESUMO

The vascular endothelial growth factor (VEGF) family and its receptors play fundamental roles not only in physiological but also in pathological angiogenesis, characteristic of cancer progression. Aiming at finding putative treatments for several malignancies, various small molecules, antibodies, or protein-based drugs have been evaluated in vitro and in vivo as VEGF inhibitors, providing efficient agents approved for clinical use. Due to the high clinical importance of VEGF, also a great number of anti-VEGF nucleic acid-based aptamers-that is, oligonucleotides able to bind with high affinity and specificity a selected biological target-have been developed as promising agents in anticancer strategies. Notable research efforts have been made in optimization processes of the identified aptamers, searching for increased target affinity and/or bioactivity by exploring structural analogues of the lead compounds. This review is focused on recent studies devoted to the development of DNA-based aptamers designed to target VEGF. Their therapeutic potential as well as their significance in the construction of highly selective biosensors is here discussed.

9.
Molecules ; 25(22)2020 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-33182593

RESUMO

Multivalent interactions frequently occur in biological systems and typically provide higher binding affinity and selectivity in target recognition than when only monovalent interactions are operative. Thus, taking inspiration by nature, bivalent or multivalent nucleic acid aptamers recognizing a specific biological target have been extensively studied in the last decades. Indeed, oligonucleotide-based aptamers are suitable building blocks for the development of highly efficient multivalent systems since they can be easily modified and assembled exploiting proper connecting linkers of different nature. Thus, substantial research efforts have been put in the construction of dimeric/multimeric versions of effective aptamers with various degrees of success in target binding affinity or therapeutic activity enhancement. The present review summarizes recent advances in the design and development of dimeric and multimeric DNA-based aptamers, including those forming G-quadruplex (G4) structures, recognizing different key proteins in relevant pathological processes. Most of the designed constructs have shown improved performance in terms of binding affinity or therapeutic activity as anti-inflammatory, antiviral, anticoagulant, and anticancer agents and their number is certainly bound to grow in the next future.


Assuntos
Aptâmeros de Nucleotídeos/química , Quadruplex G , Fosfoproteínas/química , Proteínas de Ligação a RNA/química , Anti-Inflamatórios/química , Anticoagulantes/química , Antineoplásicos/química , Antivirais/química , Complexo CD3/química , Moléculas de Adesão Celular/química , DNA/química , Dimerização , Humanos , Imunoglobulina M/química , Estrutura Secundária de Proteína , Proteínas Proto-Oncogênicas c-met/química , Pirrolidinas/química , Receptores Proteína Tirosina Quinases/química , Receptores de Antígenos de Linfócitos T/química , Fator A de Crescimento do Endotélio Vascular/metabolismo , Vitronectina/química
10.
Pharmaceuticals (Basel) ; 13(10)2020 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-33007911

RESUMO

We here report our studies on the reaction with the platinum(II) ion of a nucleoamino acid constituted by the l-2,3-diaminopropanoic acid linked to the thymine nucleobase through a methylenecarbonyl linker. The obtained new platinum complexes, characterized by spectroscopic and mass spectrometric techniques, were envisaged to exploit synergistic effects due to the presence of both the platinum center and the nucleoamino acid moiety. The latter can be potentially useful to protect the complexes from early deactivation, as well as to facilitate their cell internalization. The biological activity of the complexes in terms of antiproliferative effects was evaluated in vitro on different cancer cell lines and healthy cells, showing the best results on human cervical adenocarcinoma (HeLa) cells along with good selectivity for cancer over normal cells. In contrast, the metal-free nucleoamino acid did not show any cytotoxicity on both normal and cancer cell lines. Finally, the ability of the novel Pt(II) complexes to bind various DNA model systems was investigated by circular dichroism (CD) spectroscopy and polyacrylamide gel electrophoresis analyses proving that the newly obtained compounds can potentially target DNA, similarly to other well-known anticancer Pt complexes, with a peculiar G-quadruplex vs. duplex selectivity.

11.
Bioorg Chem ; 100: 103862, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32428744

RESUMO

Herein we present the synthesis of a l-diaminobutanoic acid (DABA)-based nucleopeptide (3), with an oligocationic backbone, realized by solid phase peptide synthesis using thymine-bearing DABA moieties alternating in the sequence with free ones. CD studies evidenced the ability of this oligothymine nucleopeptide, well soluble in aqueous solution, to alter the secondary structure particularly of complementary RNA (poly rA vs poly rU) and inosine-rich RNAs, like poly rI and poly rIC, and showed its preference in binding double vs single-stranded DNAs. Furthermore, ESI mass spectrometry revealed that 3 bound also G-quadruplex (G4) DNAs, with either parallel or antiparallel topologies (adopted in our experimental conditions by c-myc and tel22, respectively). However, it caused detectable changes only in the CD of c-myc (whose parallel G4 structure was also thermally stabilized by ~3 °C), while leaving unaltered the antiparallel structure of tel22. Interestingly, CD and UV analyses suggested that 3 induced a hybrid mixed parallel/antiparallel G4 DNA structure in a random-coil tel22 DNA obtained under salt-free buffer conditions. Titration of the random-coil telomeric DNA with 3 gave quantitative information on the stoichiometry of the obtained complex. Overall, the findings of this work suggest that DABA-based nucleopeptides are synthetic nucleic acid analogues potentially useful in antigene and antisense strategies. Nevertheless, the hexathymine DABA-nucleopeptide shows an interesting behaviour as molecular tool per se thanks to its efficacy in provoking G4 induction in random coil G-rich DNA, as well as for the possibility to bind and stabilize c-myc oncogene in a G4 structure.


Assuntos
Aminobutiratos/química , Aminobutiratos/farmacologia , DNA/metabolismo , RNA/metabolismo , Timina/análogos & derivados , Timina/farmacologia , Aminobutiratos/síntese química , DNA/química , Quadruplex G/efeitos dos fármacos , Conformação de Ácido Nucleico/efeitos dos fármacos , RNA/química , Técnicas de Síntese em Fase Sólida , Timina/síntese química
12.
Int J Mol Sci ; 21(6)2020 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-32183038

RESUMO

A focused library of newly designed monomeric and dimeric naphthalene diimides (NDIs) was analyzed in its ability to recognize specific G-quadruplex (G4) structures discriminating duplex DNA. The best G4 ligands-according to an affinity chromatography-based screening method named G4-CPG-were tested on human cancer and healthy cells, inducing DNA damage at telomeres, and in parallel, showing selective antiproliferative activity on HeLa cancer cells with IC50 values in the low nanomolar range. CD and fluorescence spectroscopy studies allowed detailed investigation of the interaction in solution with different G4 and duplex DNA models of the most promising NDI of the series, as determined by combining the biophysical and biological assays' data.


Assuntos
Antineoplásicos/química , Quadruplex G/efeitos dos fármacos , Iminas/química , Naftalenos/química , Antineoplásicos/farmacologia , Proliferação de Células/efeitos dos fármacos , Dano ao DNA , Células HeLa , Humanos , Iminas/farmacologia , Ligantes , Naftalenos/farmacologia , Telômero/efeitos dos fármacos
13.
Int J Mol Sci ; 21(6)2020 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-32183039

RESUMO

In the optimization process of nucleic acid aptamers, increased affinity and/or activity are generally searched by exploring structural analogues of the lead compound. In many cases, promising results have been obtained by dimerization of the starting aptamer. Here we studied a focused set of covalent dimers of the G-quadruplex (G4) forming anti-Vascular Endothelial Growth Factor (VEGF) V7t1 aptamer with the aim of identifying derivatives with improved properties. In the design of these covalent dimers, connecting linkers of different chemical nature, maintaining the same polarity along the strand or inverting it, have been introduced. These dimeric aptamers have been investigated using several biophysical techniques to disclose the conformational behavior, molecularity and thermal stability of the structures formed in different buffers. This in-depth biophysical characterization revealed the formation of stable G4 structures, however in some cases accompanied by alternative tridimensional arrangements. When tested for their VEGF165 binding and antiproliferative activity in comparison with V7t1, these covalent dimers showed slightly lower binding ability to the target protein but similar if not slightly higher antiproliferative activity on human breast adenocarcinoma MCF-7 cells. These results provide useful information for the design of improved dimeric aptamers based on further optimization of the linker joining the two consecutive V7t1 sequences.


Assuntos
Aptâmeros de Nucleotídeos/química , Quadruplex G , Fator A de Crescimento do Endotélio Vascular/metabolismo , Aptâmeros de Nucleotídeos/farmacologia , Proliferação de Células/efeitos dos fármacos , Humanos , Células MCF-7 , Ligação Proteica
14.
J Inorg Biochem ; 203: 110868, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31837618

RESUMO

An artificial alanine-based amino acid {(S)-2-amino-3-[4-propyl-3-(thiophen-2-yl)-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-1-yl]propanoic acid, here named TioxAla}, bearing a substituted triazolyl-thione group on the side chain and able to bind RNA biomedical targets, was here chosen as a valuable scaffold for the synthesis of new platinum complexes with potential dual action owing to the concomitant presence of the metal centre and the amino acid moiety. Three new platinum complexes, obtained from the reaction of TioxAla with K2PtCl4, were characterized by mass spectrometry, nuclear magnetic resonance and UV-vis spectroscopy: one compound (Pt1, bis-{(S)-2-amino-3-[4-propyl-3-(thiophen-2-yl)-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-1-yl]propanoate-O,S} platinum(II)) consisted of two amino acid units coordinating the Pt(II) ion; the other two, Pt2 [potassium dichloro-{(S)-2-amino-3-[4-propyl-3-(thiophen-2-yl)-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-1-yl]propanoate (O,S)} platinum(II)] and Pt3 [potassium dichloro-{(S)-2-amino-3-[4-propyl-3-(thiophen-2-yl)-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-1-yl]propanoate (O,N)} platinum(II)], were isomers bearing one TioxAla unit, and two chlorides as Pt-ligands. Pt coordination involved preferentially the amino, carboxylic and thione functions of TioxAla. By preliminary antiproliferative assays, a moderate cytotoxic activity on cancer cells was observed only for Pt2 and Pt3, while no anticancer activity was found for both the chloride-free complex (Pt1) and TioxAla. This cytotoxicity, however lower than that of cisplatin, well correlated with the marked ability, here found only for Pt2 and Pt3 complexes, to bind DNA sequences either in random coil or in structured forms (duplex and G-quadruplex), as verified by spectroscopic and spectrometric analysis.


Assuntos
Alanina/farmacologia , Antineoplásicos/farmacologia , Complexos de Coordenação/farmacologia , DNA/metabolismo , Alanina/análogos & derivados , Alanina/metabolismo , Antineoplásicos/síntese química , Antineoplásicos/metabolismo , Linhagem Celular Tumoral , Complexos de Coordenação/síntese química , Complexos de Coordenação/metabolismo , DNA/genética , Ensaios de Seleção de Medicamentos Antitumorais , Quadruplex G , Humanos , Ligantes , Platina/química
15.
Int J Biol Macromol ; 151: 1163-1172, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-31747572

RESUMO

Among polyphenols, trans-resveratrol (tRES) and trans-polydatin (tPD) exert multiple biological effects, particularly antioxidant and antiproliferative. In this work, we have investigated the interaction of tPD with three cancer-related DNA sequences able to form G-quadruplex (G4) structures, as well as with a model duplex, and compared its behaviour with tRES. Interestingly, fluorescence analysis evidenced the ability of tPD to bind all the studied DNA systems, similarly to tRES, with tRES displaying a higher ability to discriminate G4 over duplex with respect to tPD. However, neither tRES nor tPD produced significant conformational changes of the analyzed DNA upon binding, as determined by CD-titration analysis. Computational analysis and biological data confirmed the biophysical results: indeed, molecular docking evidenced the stronger interaction of tRES with the promoter of c-myc oncogene, and immunoblotting assays revealed a reduction of c-myc expression, more effective for tRES than tPD. Furthermore, in vitro assays on melanoma cells proved that tPD was able to significantly reduce telomerase activity, and inhibit cell proliferation, with tRES producing higher effects than tPD.


Assuntos
DNA/química , Quadruplex G , Glucosídeos/química , Glucosídeos/farmacologia , Resveratrol/química , Resveratrol/farmacologia , Estilbenos/química , Estilbenos/farmacologia , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Humanos , Modelos Moleculares , Conformação Molecular , Proteínas Proto-Oncogênicas c-myc/genética , Proteínas Proto-Oncogênicas c-myc/metabolismo , Análise Espectral , Relação Estrutura-Atividade
16.
Pharmaceuticals (Basel) ; 12(4)2019 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-31561546

RESUMO

The great advances in the studies on metal complexes for the treatment of different cancer forms, starting from the pioneering works on platinum derivatives, have fostered an increasingly growing interest in their properties and biomedical applications. Among the various metal-containing drugs investigated thus far, ruthenium(III) complexes have emerged for their selective cytotoxic activity in vitro and promising anticancer properties in vivo, also leading to a few candidates in advanced clinical trials. Aiming at addressing the solubility, stability and cellular uptake issues of low molecular weight Ru(III)-based compounds, some research groups have proposed the development of suitable drug delivery systems (e.g., taking advantage of nanoparticles, liposomes, etc.) able to enhance their activity compared to the naked drugs. This review highlights the unique role of Ru(III) complexes in the current panorama of anticancer agents, with particular emphasis on Ru-containing nanoformulations based on the incorporation of the Ru(III) complexes into suitable nanocarriers in order to enhance their bioavailability and pharmacokinetic properties. Preclinical evaluation of these nanoaggregates is discussed with a special focus on the investigation of their mechanism of action at a molecular level, highlighting their pharmacological potential in tumour disease models and value for biomedical applications.

17.
Nucleic Acids Res ; 47(15): 8318-8331, 2019 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-31276595

RESUMO

The G-quadruplex-forming VEGF-binding aptamer V7t1 was previously found to be highly polymorphic in a K+-containing solution and, to restrict its conformational preferences to a unique, well-defined form, modified nucleotides (LNA and/or UNA) were inserted in its sequence. We here report an in-depth biophysical characterization of V7t1 in a Na+-rich medium, mimicking the extracellular environment in which VEGF targeting should occur, carried out combining several techniques to analyse the conformational behaviour of the aptamer and its binding to the protein. Our results demonstrate that, in the presence of high Na+ concentrations, V7t1 behaves in a very different way if subjected or not to annealing procedures, as evidenced by native gel electrophoresis, size exclusion chromatography and dynamic light scattering analysis. Indeed, not-annealed V7t1 forms both monomeric and dimeric G-quadruplexes, while the annealed oligonucleotide is a monomeric species. Remarkably, only the dimeric aptamer efficiently binds VEGF, showing higher affinity for the protein compared to the monomeric species. These findings provide new precious information for the development of improved V7t1 analogues, allowing more efficient binding to the cancer-related protein and the design of effective biosensors or theranostic devices based on VEGF targeting.


Assuntos
Aptâmeros de Nucleotídeos/metabolismo , Quadruplex G , Oligonucleotídeos/metabolismo , Fator A de Crescimento do Endotélio Vascular/metabolismo , Aptâmeros de Nucleotídeos/química , Aptâmeros de Nucleotídeos/genética , Ligação Competitiva , Dicroísmo Circular , Conformação de Ácido Nucleico , Oligonucleotídeos/química , Oligonucleotídeos/genética , Potássio/química , Potássio/metabolismo , Ligação Proteica , Sódio/química , Sódio/metabolismo , Espectrofotometria Ultravioleta , Fator A de Crescimento do Endotélio Vascular/genética
18.
Int J Biol Macromol ; 133: 839-849, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31022491

RESUMO

Exploiting a variant of SELEX called "Ligand-Guided Selection" (LI-GS), we recently identified two novel truncated G-rich aptamers, called R1.2 and R1.3, specific for membrane-bound IgM (mIgM), the hallmark of B cells. Herein, the conformational behaviour of these aptamers has been analysed by multiple biophysical methods. In order to investigate their functional secondary structures, these studies have been carried out in pseudo-physiological buffers mimicking different cellular environments. Both aptamers proved to be highly polymorphic, folding into stable, unimolecular G-quadruplex structures in K+-rich buffers. In turn, in buffered solutions containing Na+/Mg2+ ions, R1.2 and R1.3 formed mainly duplex structures. Remarkably, these aptamers were able to effectively bind mIgM on B-cell lymphoma exclusively in the presence of potassium ions. These findings demonstrate the key role of G-quadruplex folding in the molecular recognition and efficient binding of R1.2 and R1.3 to mIgM expressed in lymphoma and leukemia cells, providing a precious rational basis for the design of effective aptamer-based biosensors potentially useful for the detection of cancer-relevant biomarkers.


Assuntos
Aptâmeros de Nucleotídeos/química , Aptâmeros de Nucleotídeos/metabolismo , Quadruplex G , Imunoglobulina M/metabolismo , Simulação por Computador , Humanos
19.
Future Med Chem ; 2019 02 25.
Artigo em Inglês | MEDLINE | ID: mdl-30801198

RESUMO

AIM: Our goal is to evaluate benzodifuran-based scaffolds for biomedical applications. METHODOLOGY: We here explored the anticancer and anti-amyloid activities of a novel compound (BZ4) in comparison with other known benzodifuran analogs, previously studied in our group, and we have explored its ability to interact with different DNA model systems. RESULTS: BZ4 shows antiproliferative activity on different cancer cells; does not affect noncancerous control cells and alters the aggregation properties of ß-amyloid, as ascertained by circular dichroism, fluorescence spectroscopy and scanning electron microscopy analysis. An overall, qualitative picture on the mechanistic aspects related to the biological activities is discussed in light of the dynamic light scattering, UV, circular dichroism and fluorescence data, as well as of the metal ion-binding properties of BZ4.

20.
Inorg Chem ; 58(2): 1216-1223, 2019 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-30614697

RESUMO

The RuIII-based prodrug AziRu efficiently binds to proteins, but the mechanism of its release is still disputed. Herein, in order to test the hypothesis of a reduction-mediated Ru release from proteins, a Raman-assisted crystallographic study on AziRu binding to a model protein (hen egg white lysozyme), in two different oxidation states, RuII and RuIII, was carried out. Our results indicate Ru reduction, but the Ru release upon reduction is dependent on the reducing agent. To better understand this process, a pH-dependent, spectroelectrochemical surface-enhanced Raman scattering (SERS) study was performed also on AziRu-functionalized Au electrodes as a surrogate and simplest model system of RuII- and RuIII-based drugs. This SERS study provided a p Ka of 6.0 ± 0.4 for aquated AziRu in the RuIII state, which falls in the watershed range of pH values separating most cancer environments from their physiological counterparts. These experiments also indicate a dramatic shift of the redox potential E0 by >600 mV of aquated AziRu toward more positive potentials upon acidification, suggesting a selective AziRu reduction in cancer lumen but not in healthy ones. It is expected that the nature of the ligands (e.g., pyridine vs imidazole, present in well-known RuIII complex NAMI-A) will modulate the p Ka and E0, without affecting the underlying reaction mechanism.


Assuntos
Muramidase/química , Pró-Fármacos/química , Rutênio/química , Sítios de Ligação , Concentração de Íons de Hidrogênio , Estrutura Molecular , Muramidase/metabolismo , Pró-Fármacos/síntese química
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