title: Molecular Recognition of Parallel DNA Quadruplex d(TTAGGGT)4 by Mitoxantrone: Binding with 1:2 Stoichiometry Leading to Thermal Stabilization and Telomerase Inhibition.
abstract: The interaction of the anthraquinone derivative mitoxantrone, a semisynthetic anti-cancer drug with two non-planar side chains, with heptamer G-quadruplex d(TTAGGGT)4 , which contains the human telomere DNA sequence, was evaluated by differential scanning calorimetry, fluorescence Job plotting, absorption, and NMR and CD spectroscopy. Binding led to thermal stabilization of DNA (ΔTm =13-20 °C). The spectra revealed that two mitoxantrone molecules bind externally at two sites of the DNA quadruplex as monomers, by partial insertion of the chromophore and side-chain interaction at the grooves. The inhibition of telomerase (IC50 =2 μM), as determined by a TRAP assay, can be attributed to thermal stabilization of the DNA quadruplex because of the interactions with mitoxantrone. The studies revealed highly specific molecular recognition between a ligand and a parallel-stranded G-quadruplex; this might serve as a platform for the rational design of new drugs.
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, India.
authors.forename: Sweta
authors.initials: S
authors.lastname: Tripathi
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, India.
authors.forename: Tarikere Palakshan
authors.initials: TP
authors.lastname: Pradeep
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, India. ritubfbs@iitr.ac.in.
authors.forename: Ritu
authors.initials: R
authors.lastname: Barthwal
mesh_terms: D002152:Calorimetry, Differential Scanning; D002942:Circular Dichroism; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D054856:G-Quadruplexes; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008942:Mitoxantrone / Q000737:chemistry* / Q000494:pharmacology; D011485:Protein Binding; D055550:Protein Stability; D019098:Telomerase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013696:Temperature
chemical_list: D004791:Enzyme Inhibitors; D008942:Mitoxantrone; D019098:Telomerase
keywords: G-quadruplexes; NMR spectroscopy; circular dichroism; mitoxantrone; telomerase inhibition; thermal stabilization