title: Selective interaction of ethidium derivatives with quadruplexes: an equilibrium dialysis and electrospray ionization mass spectrometry analysis.
abstract: The telomeric G-rich single-stranded DNA can adopt in vitro an intramolecular quadruplex structure, which has been shown to directly inhibit telomerase activity. The reactivation of this enzyme in immortalized and most cancer cells suggests that telomerase is a relevant target in oncology, and telomerase inhibitors have been proposed as new potential anticancer agents. In this paper, we have analyzed the selectivity of four ethidium derivatives and ethidium itself toward different G-quadruplex species, with electrospray mass spectrometry and competitive equilibrium dialysis and evaluated their inhibitory properties against telomerase. A selectivity profile may be obtained through electrospray ionization mass spectrometry (ESI-MS), which is in fair agreement with competitive equilibrium dialysis data. It also provides unambiguous data on the number of binding sites per nucleic acid (maximal number of two ethidium derivatives per quadruplex, in agreement with external stacking). Our experiments also demonstrate that one compound (4) is the most active and selective G-quadruplex ligand within this series and the most selective telomerase inhibitor in a modified TRAP-G4 assay.
authors.affiliation: The Biospectroscopy Laboratory, Chemistry Institute, Bât. B6c, B-4000 Liege, Belgium.
authors.forename: Frederic
authors.initials: F
authors.lastname: Rosu
authors.forename: Edwin
authors.initials: E
authors.lastname: De Pauw
authors.forename: Lionel
authors.initials: L
authors.lastname: Guittat
authors.forename: Patrizia
authors.initials: P
authors.lastname: Alberti
authors.forename: Laurent
authors.initials: L
authors.lastname: Lacroix
authors.forename: Patrick
authors.initials: P
authors.lastname: Mailliet
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Riou
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Mergny
mesh_terms: D001665:Binding Sites; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D003956:Dialysis; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000378:metabolism; D004996:Ethidium / Q000737:chemistry* / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D005456:Fluorescent Dyes / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008024:Ligands; D015394:Molecular Structure; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D019098:Telomerase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016615:Telomere / Q000737:chemistry / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D008024:Ligands; D009841:Oligonucleotides; D004247:DNA; D019098:Telomerase; D004996:Ethidium