Discovery of the first dual G-triplex/G-quadruplex stabilizing compound: a new opportunity in the targeting of G-rich DNA structures?
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.



The discovery of molecules able to bind and stabilize G-triplex structures is highly appealing, but their transient state makes challenging their recognition. These findings suggest that the identification of ligands with dual G-triplex/G-quadruplex stabilizing properties may represent a new route for the design of anticancer agents targeting the G-rich DNA structures. This article is part of a Special Issue entitled "G-quadruplex" Guest Editor: Dr. Concetta Giancola and Dr. Daniela Montesarchio.
Department of Pharmacy, University of Naples Federico II, via D. Montesano 49, 80131 Naples, Italy.
Jussara
J
Amato
Department of Pharmacy, University of Naples Federico II, via D. Montesano 49, 80131 Naples, Italy.
Alessia
A
Pagano
DiSTABiF, Second University of Naples, via Vivaldi 43, 81100 Caserta, Italy.
Sandro
S
Cosconati
DiSTABiF, Second University of Naples, via Vivaldi 43, 81100 Caserta, Italy.
Giorgio
G
Amendola
Department of Pharmacy, University of Naples Federico II, via D. Montesano 49, 80131 Naples, Italy.
Iolanda
I
Fotticchia
Department of Pharmacy, University of Naples Federico II, via D. Montesano 49, 80131 Naples, Italy.
Nunzia
N
Iaccarino
Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy.
Jessica
J
Marinello
Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy.
Alessio
A
De Magis
Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy.
Giovanni
G
Capranico
Department of Pharmacy, University of Naples Federico II, via D. Montesano 49, 80131 Naples, Italy.
Ettore
E
Novellino
Department of Pharmacy, University of Naples Federico II, via D. Montesano 49, 80131 Naples, Italy.
Bruno
B
Pagano
Department of Pharmacy, University of Naples Federico II, via D. Montesano 49, 80131 Naples, Italy. Electronic address: antonio.randazzo@unina.it.
Antonio
A
Randazzo
D000970:Antineoplastic Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D001665:Binding Sites; D002152:Calorimetry, Differential Scanning; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002942:Circular Dichroism; D004273:DNA, Neoplasm / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015195:Drug Design; D054856:G-Quadruplexes / Q000187:drug effects*; D006151:Guanosine / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D020128:Inhibitory Concentration 50; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D062105:Molecular Docking Simulation; D063347:Native Polyacrylamide Gel Electrophoresis; D012516:Osteosarcoma / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D013329:Structure-Activity Relationship; D013997:Time Factors
D000970:Antineoplastic Agents; D004273:DNA, Neoplasm; D008024:Ligands; D006151:Guanosine
Anticancer agents; Drug discovery; G-quadruplex; G-triplex; Ligand