on Analytica chimica acta
by Platella C, Musumeci D, Arciello A, Doria F, Freccero M, Randazzo A, Amato J, Pagano B, Montesarchio D
Target selectivity is one of the main challenges in the search for small molecules able to act as effective and non-toxic anticancer and/or antiviral drugs. To achieve this goal, handy, rapid and reliable High Throughput Screening methodologies are needed. We here describe a novel functionalization for the solid phase synthesis of oligonucleotides on Controlled Pore Glass, including a flexible hexaethylene glycol spacer linking the first nucleoside through the nucleobase via a covalent bond stable to the final deprotection step. This allowed us preparing fully deprotected oligonucleotides still covalently attached to their supports. In detail, on this support we performed both the on-line synthesis of different secondary structure-forming oligonucleotides and the affinity chromatography-based screenings of conformation-selective G-quadruplex ligands. By using a fluorescent core-extended naphthalene diimide with different emitting response upon binding to sequences folding into G-quadruplexes of different topologies, we have been able to discriminate not only G-quadruplex vs. duplex DNA structures, but also different G-quadruplex conformations on the glass beads by confocal microscopy.
on Chemical communications (Cambridge, England)
by Amato J, Madanayake TW, Iaccarino N, Novellino E, Randazzo A, Hurley LH, Pagano B
This communication reports on a possible distinct role of HMGB1 protein. Biophysical studies revealed that HMGB1 binds and stabilizes the G-quadruplex of the KRAS promoter element that is responsible for most of the transcriptional activity. Biological data showed that inhibition of HMGB1 increases KRAS expression. These results suggest that HMGB1 could play a role in the gene transcriptional regulation via the functional recognition of the G-quadruplex.
by Amato J, Pagano A, Capasso D, Di Gaetano S, Giustiniano M, Novellino E, Randazzo A, Pagano B
Targeting of G-quadruplex-forming DNA in BCL2 gene promoter to inhibit the expression of anti-apoptotic Bcl-2 protein represents an attractive opportunity in cancer treatment. So far, efforts made in the discovery of molecules able to target BCL2 G-quadruplex mainly succeeded in the identification of ligands with poor drug-like properties. Here, a small series of furo[2,3-d]pyridazin-4(5H)-one derivatives were evaluated as a new class of drug-like G-quadruplex-targeting compounds. Biophysical studies showed that two derivatives could effectively bind to BCL2 G-quadruplex with good selectivity. Moreover, one of such ligands appreciably inhibited BCL2 gene transcription, with a substantial reduction of protein expression level, and showed significant cytotoxicity on the human T lymphoblastoid cell line Jurkat.
on Molecules (Basel, Switzerland)
by Pagano B, Caterino M, Filosa R, Giancola C
Harmine belongs to a group of β-carboline alkaloids endowed with antitumor properties. Harmine and its derivatives are thought to bind to DNA and interfere with topoisomerase activities. We investigated the base-dependent binding of harmine, and three of its synthetic anticancer-active derivatives to the genomic DNA from calf thymus and two synthetic 20-mer double helices, the poly(dG-dC)·poly(dG-dC) and the poly(dA-dT)·poly(dA-dT), by means of UV-Vis and circular dichroism (CD) spectroscopies. The data show that the DNA binding and stabilising properties of the investigated derivatives are base pair-dependent. These results could be used as a guide to design and develop further bioactive analogues.
on Journal of medicinal chemistry
by Salvati E, Botta L, Amato J, Di Leva FS, Zizza P, Gioiello A, Pagano B, Graziani G, Tarsounas M, Randazzo A, Novellino E, Biroccio A, Cosconati S
G-quadruplex stabilizers are an established opportunity in anticancer chemotherapy. To circumvent the antiproliferative effects of G4 ligands, cancer cells recruit PARP enzymes at telomeres. Herein, starting from the structural similarity of a potent G4 ligand previously discovered by our group and a congeneric PARP inhibitor, a library of derivatives was synthesized to discover the first dual G4/PARP ligand. We demonstrate that a properly decorated thieno[3,2-c]quinolin-4(5H)-one stabilizes the G4 fold in vitro and in cells, induces a DNA damage response localized to telomeres, inhibits PARylation in cells, and has an antiproliferative effect in BRCA2 deficient tumor cells.
on Journal of the American Chemical Society
by Gajarský M, Živković ML, Stadlbauer P, Pagano B, Fiala R, Amato J, Tomáška L, Šponer J, Plavec J, Trantírek L
In this study, we report the first atomic resolution structure of a stable G-hairpin formed by a natively occurring DNA sequence. An 11-nt long G-rich DNA oligonucleotide, 5'-d(GTGTGGGTGTG)-3', corresponding to the most abundant sequence motif in irregular telomeric DNA from Saccharomyces cerevisiae (yeast), is demonstrated to adopt a novel type of mixed parallel/antiparallel fold-back DNA structure, which is stabilized by dynamic G:G base pairs that transit between N1-carbonyl symmetric and N1-carbonyl, N7-amino base-pairing arrangements. Although the studied sequence first appears to possess a low capacity for base pairing, it forms a thermodynamically stable structure with a rather complex topology that includes a chain reversal arrangement of the backbone in the center of the continuous G-tract and 3'-to-5' stacking of the terminal residues. The structure reveals previously unknown principles of the folding of G-rich oligonucleotides that could be applied to the prediction of natural and/or the design of artificial recognition DNA elements. The structure also demonstrates that the folding landscapes of short DNA single strands is much more complex than previously assumed.
on Proceedings of the National Academy of Sciences of the United States of America
by Moraca F, Amato J, Ortuso F, Artese A, Pagano B, Novellino E, Alcaro S, Parrinello M, Limongelli V
G-quadruplexes (G4s) are higher-order DNA structures typically present at promoter regions of genes and telomeres. Here, the G4 formation decreases the replicative DNA at each cell cycle, finally leading to apoptosis. The ability to control this mitotic clock, particularly in cancer cells, is fascinating and passes through a rational understanding of the ligand/G4 interaction. We demonstrate that an accurate description of the ligand/G4 binding mechanism is possible using an innovative free-energy method called funnel-metadynamics (FM), which we have recently developed to investigate ligand/protein interaction. Using FM simulations, we have elucidated the binding mechanism of the anticancer alkaloid berberine to the human telomeric G4 (d[AG3(T2AG3)3]), computing also the binding free-energy landscape. Two ligand binding modes have been identified as the lowest energy states. Furthermore, we have found prebinding sites, which are preparatory to reach the final binding mode. In our simulations, the ions and the water molecules have been explicitly represented and the energetic contribution of the solvent during ligand binding evaluated. Our theoretical results provide an accurate estimate of the absolute ligand/DNA binding free energy ([Formula: see text] = -10.3 ± 0.5 kcal/mol) that we validated through steady-state fluorescence binding assays. The good agreement between the theoretical and experimental value demonstrates that FM is a most powerful method to investigate ligand/DNA interaction and can be a useful tool for the rational design also of G4 ligands.
on Biochimica et biophysica acta
by Musumeci D, Amato J, Zizza P, Platella C, Cosconati S, Cingolani C, Biroccio A, Novellino E, Randazzo A, Giancola C, Pagano B, Montesarchio D
G-quadruplex (G4) structures are key elements in the regulation of cancer cell proliferation and their targeting is deemed to be a promising strategy in anticancer therapy.
on Biochimica et biophysica acta
by Amato J, Pagano A, Cosconati S, Amendola G, Fotticchia I, Iaccarino N, Marinello J, De Magis A, Capranico G, Novellino E, Pagano B, Randazzo A
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.
on Journal of medicinal chemistry
by Amato J, Morigi R, Pagano B, Pagano A, Ohnmacht S, De Magis A, Tiang YP, Capranico G, Locatelli A, Graziadio A, Leoni A, Rambaldi M, Novellino E, Neidle S, Randazzo A
G-Quadruplex-binding compounds are currently perceived as possible anticancer therapeutics. Here, starting from a promising lead, a small series of novel hydrazone-based compounds were synthesized and evaluated as G-quadruplex binders. The in vitro G-quadruplex-binding properties of the synthesized compounds were investigated employing both human telomeric and oncogene promoter G-quadruplexes with different folding topologies as targets. The present investigation led to the identification of potent G-quadruplex stabilizers with high selectivity over duplex DNA and preference for one G-quadruplex topology over others. Among them, selected derivatives have been shown to trap G-quadruplex structures in the nucleus of cancer cells. Interestingly, this behavior correlates with efficient cytotoxic activity in human osteosarcoma and colon carcinoma cells.