Title
Discovery of the first dual G-triplex/G-quadruplex stabilizing compound: a new opportunity in the targeting of G-rich DNA structures?
Author
Jussara Amato, Alessia Pagano, Sandro Cosconati, Giorgio Amendola, Iolanda Fotticchia, Nunzia Iaccarino, Jessica Marinello, Alessio De Magis, Giovanni Capranico, Ettore Novellino, Bruno Pagano, Antonio Randazzo
Year
2016
Journal
Biochimica et Biophysica Acta (BBA) - General Subjects
Abstract
Guanine-rich DNA motifs can form non-canonical structures known as G-quadruplexes, whose role in tumorigenic processes makes them attractive drug-target candidates for cancer therapy. Recent studies revealed that the folding and unfolding pathways of G-quadruplexes proceed through a quite stable intermediate named G-triplex. Virtual screening was employed to identify a small set of putative G-triplex ligands. The G-triplex stabilizing properties of these compounds were analyzed by CD melting assay. DSC, non-denaturing gel electrophoresis, NMR and molecular modeling studies were performed to investigate the interaction between the selected compound 1 and G-rich DNA structures. Cytotoxic activity of 1 was evaluated by MTT cell proliferation assay. The experiments led to the identification of a promising hit that was shown to bind preferentially to G-triplex and parallel-stranded G-quadruplexes over duplex and antiparallel G-quadruplexes. Molecular modeling results suggested a partial end-stacking of 1 to the external G-triad/G-tetrads as a binding mode. Biological assays showed that 1 is endowed with cytotoxic effect on human osteosarcoma cells. A tandem application of virtual screening along with the experimental investigation was employed to discover a G-triplex-targeting ligand. Experiments revealed that the selected compound actually acts as a dual G-triplex/G-quadruplex stabilizer, thus stimulating further studies aimed at its optimization.
Instrument
J-815
Keywords
Circular dichroism, DNA structure, Ligand binding, Thermal stability, Thermodynamics, Biochemistry