UMR9187 / U1196 – Chimie et Modélisation pour la Biologie du Cancer (CMBC)

Publications de l’unité

Année de publication : 2002

Jean-Louis Mergny, Jean-François Riou, Patrick Mailliet, Marie-Paule Teulade-Fichou, Eric Gilson (2002 Feb 14)

Natural and pharmacological regulation of telomerase.

Nucleic acids research : 30 : 839-865 : DOI : 10.1093/nar/30.4.839 En savoir plus
Résumé

The extremities of eukaryotic chromosomes are called telomeres. They have a structure unlike the bulk of the chromosome, which allows the cell DNA repair machinery to distinguish them from ‘broken’ DNA ends. But these specialised structures present a problem when it comes to replicating the DNA. Indeed, telomeric DNA progressively erodes with each round of cell division in cells that do not express telomerase, a specialised reverse transcriptase necessary to fully duplicate the telomeric DNA. Telomerase is expressed in tumour cells but not in most somatic cells and thus telomeres and telomerase may be proposed as attractive targets for the discovery of new anticancer agents.

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P Alberti, J Ren, M P Teulade-Fichou, L Guittat, J F Riou, J Chaires, C Hélène, J P Vigneron, J M Lehn, J L Mergny (2002 Jan 16)

Interaction of an acridine dimer with DNA quadruplex structures.

Journal of biomolecular structure & dynamics : 19 : 505-513 : DOI : 10.1080/07391102.2001.10506758 En savoir plus
Résumé

The reactivation of telomerase activity in most cancer cells supports the concept that telomerase is a relevant target in oncology, and telomerase inhibitors have been proposed as new potential anticancer agents. The telomeric G-rich single-stranded DNA can adopt an intramolecular G-quadruplex structure in vitro, which has been shown to inhibit telomerase activity. The C-rich sequence can also adopt a quadruplex (intercalated) structure (i-DNA). Two acridine derivatives were shown to increase the melting temperature of the G- quadruplex and the C-quadruplex at 1 microM dye concentration. The increase in Tm value of the G-quadruplex was associated with telomerase inhibition in vitro. The most active compound, « BisA », showed an IC(50) value of 0.75 microM in a standard TRAP assay.

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Année de publication : 2001

M P Teulade-Fichou, D Perrin, A Boutorine, D Polverari, J P Vigneron, J M Lehn, J S Sun, T Garestier, C Helene (2001 Sep 20)

Direct photocleavage of HIV-DNA by quinacridine derivatives triggered by triplex formation.

Journal of the American Chemical Society : 123 : 9283-9292 : DOI : 10.1021/ja0109040 En savoir plus
Résumé

Amino-p-quinacridine compounds (PQs) have been shown to stabilize strongly and specifically triple-helical DNA. Moreover, these derivatives display photoactive properties that make them efficient DNA cleavage agents. We exploited these two properties (triplex-specific binding and photoactivity) to selectively cleave a double-stranded (ds)DNA sequence present in the HIV-1 genome. Cleavage was first carried out on a linearized plasmid (3300 bp) containing the HIV polypurine tract (PPT) that allowed targeting by a triplex-forming oligonucleotide (TFO). PQ3, the most active compound of the series, efficiently cleaved double-stranded DNA in the vicinity of the PPT when this sequence had formed a triplex with a 16-mer TFO. Investigation of the cleavage at the molecular level was addressed on a short DNA fragment (56 bp); the photoinduced cleavage by PQ3 occurred only in the presence of the triple helix. Nevertheless, unusual cleavage patterns were observed:  damage was observed at guanines located 6−9 bp away from the end of the triple helical site. This cleavage is very efficient (up to 60%), does not require alkaline treatment, and is observed on both strands. A quinacridine−TFO conjugate produced the same cleavage pattern. This observation, along with others, excludes the hypothesis of a triplex-induced allosteric binding site of PQ3 adjacent to the damaged sequence and indicates that PQ3 preferentially binds in the vicinity of the 5‘-triplex junction. Irradiation in the presence of TFO-conjugates with acridine (an intercalative agent) and with the tripeptide lys-tryp-lys led to a complete inhibition of the photocleavage reaction. These results are interpreted in terms of competitive binding and of electron-transfer quenching. Together with the findings of simple mechanistic investigations, they led to the conclusion that the photoinduced damage proceeds through a direct electron transfer between the quinacridine and the guanines. This study addresses the chemical mechanism leading to strand breakage and characterizes the particular photosensitivity of the HIV−DNA target sequence which could be an oxidative hot spot for addressed photoinduced strand scission by photosensitizers.

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J L Mergny, L Lacroix, M P Teulade-Fichou, C Hounsou, L Guittat, M Hoarau, P B Arimondo, J P Vigneron, J M Lehn, J F Riou, T Garestier, C Hélène (2001 Mar 15)

Telomerase inhibitors based on quadruplex ligands selected by a fluorescence assay.

Proceedings of the National Academy of Sciences of the United States of America : 98 : 3062-3067 : DOI : 10.1073/pnas.051620698 En savoir plus
Résumé

The reactivation of telomerase activity in most cancer cells supports the concept that telomerase is a relevant target in oncology, and telomerase inhibitors have been proposed as new potential anticancer agents. The telomeric G-rich single-stranded DNA can adopt in vitro an intramolecular quadruplex structure, which has been shown to inhibit telomerase activity. We used a fluorescence assay to identify molecules that stabilize G-quadruplexes. Intramolecular folding of an oligonucleotide with four repeats of the human telomeric sequence into a G-quadruplex structure led to fluorescence excitation energy transfer between a donor (fluorescein) and an acceptor (tetramethylrhodamine) covalently attached to the 5′ and 3′ ends of the oligonucleotide, respectively. The melting of the G-quadruplex was monitored in the presence of putative G-quadruplex-binding molecules by measuring the fluorescence emission of the donor. A series of compounds (pentacyclic crescent-shaped dibenzophenanthroline derivatives) was shown to increase the melting temperature of the G-quadruplex by 2–20°C at 1 μM dye concentration. This increase in Tm value was well correlated with an increase in the efficiency of telomerase inhibition in vitro. The best telomerase inhibitor showed an IC50 value of 28 nM in a standard telomerase repeat amplification protocol assay. Fluorescence energy transfer can thus be used to reveal the formation of four-stranded DNA structures, and its stabilization by quadruplex-binding agents, in an effort to discover new potent telomerase inhibitors.

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Année de publication : 2000

M P Teulade-Fichou, M Fauquet, O Baudoin, J P Vigneron, J M Lehn (2000 Jan 1)

DNA double helix destabilizing properties of cyclobisintercaland compounds and competition with a single strand binding protein.

Bioorganic & medicinal chemistry : 8 : 215-222 : DOI : 10.1016/s0968-0896(99)00283-7 En savoir plus
Résumé

The DNA helix destabilizing activity of a series of cyclobisintercaland compounds (CBIs) has been evaluated by measuring their ability to displace a 32P-labelled oligonucleotide primer (17-mer) hybridized to the single stranded DNA of M13. This destabilizing activity appears to be strongly dependent on the cyclic structure (the linear acyclic references are inactive) and the size of the macrocycle; both features being known to determine the preferential binding of the compound to ssDNA. Interestingly, CBIs induced the dissociation of the duplex template in a concentration range (0.5-1 microM) close to that required for the destabilizing activity of single stranded DNA binding proteins (SSBs). Therefore competition experiments between CBIs and an SSB protein (Eco SSB) for binding to a single stranded oligonucleotide target (36-mer) have been performed through gel electrophoresis and nitrocellulose binding assays and strong inhibitory effects on the formation of the SSB:36-mer complex have been observed.

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Année de publication : 1999

M Jourdan, J Garcia, J Lhomme, M P Teulade-Fichou, J P Vigneron, J M Lehn (1999 Nov 26)

Threading bis-intercalation of a macrocyclic bisacridine at abasic sites in DNA: nuclear magnetic resonance and molecular modeling study.

Biochemistry : 38 : 14205-14213 : DOI : 10.1021/bi991111h En savoir plus
Résumé

The macrocyclic bisacridine (CBA) has been reported previously to specifically recognize single-stranded nucleic acid structures, especially DNA hairpins. The binding of the drug with an abasic site-containing oligonucleotide, was investigated by 1H NMR and molecular modeling. We have used a DNA undecamer, the d(C1G2C3A4C5X6C7A8C9G10C11)·d(G12C13G14T15G16T17G18T19G20C21G22) duplex in which the X residue is a stable analogue of the abasic site [3-hydroxy-2-(hydroxymethyl) tetrahydrofuran]. Analysis of the NMR data reveals that the bisacridine molecule forms two different intercalation complexes in a 80/20 (± 10) ratio. For the major complex, a molecular modeling study was performed guided by nineteen intermolecular drug−DNA restraints, determined from NOESY spectra. In this model, the ligand interacts in the threading binding mode with an acridine ring intercalated between the C7−A8 and T15−G16 base pairs, while the other acridine ring resides in the abasic pocket. The two linker chains are positioned in the minor and in the major groove, respectively. A comparable study was performed to evaluate the interaction of CBA with the parent unmodified duplex in which X6 was replaced by an adenine residue. No complex formation was observed when operating in identical conditions. This shows the selective binding of CBA to the abasic site and its potential interest to target the abasic site lesion.

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Année de publication : 1998

A J Blacker, M P Teulade-Fichou, J P Vigneron, M Fauquet, J M Lehn (1998 Mar 17)

Selective photocleavage of single-stranded nucleic acids by cyclobisintercaland molecules.

Bioorganic & medicinal chemistry letters : 8 : 601-606 : DOI : 10.1016/s0960-894x(98)00085-7 En savoir plus
Résumé

Irradiation of mixtures of a single-stranded circular plasmid and of a double-stranded supercoiled DNA in presence of the cyclobisintercaland compounds 2 or 3 shows that these reagents effect the selective photocleavage of the single-stranded entity. Furthermore, 2 also cleaves tRNAasp preferentially at single-stranded domains.

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Année de publication : 1997

A Slama-Schwok, F Peronnet, E Hantz-Brachet, E Taillandier, M P Teulade-Fichou, J P Vigneron, M Best-Belpomme, J M Lehn (1997 Jul 1)

A macrocyclic bis-acridine shifts the equilibrium from duplexes towards DNA hairpins.

Nucleic acids research : 25 : 2574-2581 : DOI : 10.1093/nar/25.13.2574 En savoir plus
Résumé

Nucleic acids can undergo dynamic conformational changes associated with the regulation of biological processes. A molecule presenting larger affinities for alternative structures relative to a duplex is expected to modify such conformational equilibria. We have previously reported that macrocyclic bis-acridine binds preferentially to single-stranded regions, especially DNA hairpins, due to steric effects. Here, we show, using gel electrophoresis, fluorescence and melting temperature experiments, that the macrocycle bis-acridine shifts an equilibrium from a duplex towards the corresponding hairpins. Competition experiments enlighten the higher affinity of the macrocycle for hairpins compared with double-stranded DNA. The macrocycle bis-acridine destabilizes a synthetic polynucleotide, by the formation of premelted areas. By extrapolation, the macrocycle bis-acridine should be able to disrupt, at least locally, genomic DNA duplexes and to stabilize unpaired areas, especially palindromic ones forming hairpins. Such macrocyclic compounds may have potential applications in the therapy of diseases involving hairpins.

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