Targeting Human Gastrointestinal Stromal Tumor Cells with a Quadruplex-Binding Small Molecule (original) (raw)
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Targeting pancreatic cancer with a G-quadruplex ligand
Bioorganic & Medicinal Chemistry, 2011
The integrity of telomeres in most cancer cells is maintained by the action of the telomerase enzyme complex, which catalyzes the synthesis of telomeric DNA repeats in order to replace those lost during replication. Telomerase is especially up-regulated in metastatic cancer and is thus emerging as a major therapeutic target. One approach to telomerase inhibition involves the sequestration of the singlestranded 3 0 ends of telomeric DNA into higher-order quadruplex structures. We have recently shown that tetra-substituted naphthalene diimide compounds are potent quadruplex-stabilizing molecules with telomerase inhibitory activity in cells. We show here that one such compound, BMSG-SH-3, which has been optimized by computer modeling, has significant in vivo antitumor activity against a model for pancreatic cancer, a cancer that is especially resistant to current therapies. A large reduction in telomerase activity in treated tumors was observed and the naphthalene diimide compound was found to be selectively localized in the treated tumors. We find that the expression of the therapeutically important chaperone protein HSP90, a regulator of telomerase is also reduced in vivo by BMSG-SH-3 treatment. The compound is a potent stabilizer of two G-quadruplex sequences found in the promoter region of the HSP90 gene, as well as a G-quadruplex from human telomeric DNA. It is proposed that the simultaneous targeting of these quadruplexes may be an effective anti-tumor strategy.
GW-2974 is a potent inhibitor for the tyrosine kinase receptor. It inhibits EGFR and ErbB-2 in tumor cells with high selectivity towards malignant over normal cells. SCH-442416 is a potent antagonist for adenosine receptor with high selectivity towards human A2a receptor over other adenosine receptors. The two compounds were reported to possess antitumor properties. In this work, we studied the stabilization of human telomeric G-quadruplex DNA by GW-2974 and SCH-442416, as a probable underlying mechanism for their anticancer effects. Interactions of human telomeric G-quadruplex DNA - sequence AG3(TTAGGG)3 – with both compounds were studied using UV-Vis, fluorescence quenching, melting temperature, circular dichroism and molecular docking techniques. Results obtained from absorption, fluorescence and CD indicated that GW2974 and SCH-442416 interacted with G-quadruplex through intercalation binding modes on two types of dependent binding sites. Binding affinities of 1.3x108 - 1.72x106...
International Journal of Oncology, 2014
naphthalene diimide (nDi) derivatives have shown high affinity for telomeric guanine (G)-quadruplexes and good antiproliferative activity in different human tumor experimental models. A trisubstituted compound (H-NDI-NMe 2 ) has been reported to stabilize the telomeric G-quadruplex and to cause telomere dysfunction and downregulation of telomerase expression. We further investigated its mechanism of action by analyzing the capability of the molecule to interfere with the expression levels of oncogenes, such as MYC, telome rase reverse transcriptase (TERT), KIT and BCL2, known to bear G-quadruplex-forming sequences within their promoters, in human tumor cell lines of different histological origin. Exposure to H-NDI-NMe 2 resulted in a cell type-dependent perturbation of the expression levels of the four selected genes. Biophysical and molecular analyses revealed that H-NDI-NMe 2 bound with high affinity and effectively stabilized mainly MYC and BCL2, which share long sequences and the possibility of multiple G-quadruplex folding. The mRNA levels of both genes, but not protein amounts were affected by NDI treatment. Global gene expression analysis showed modulation of genes implicated in telomere function and mechanisms of cancer; however, G-quadruplex-mediated regulation of gene expression by H-NDI-NMe 2 was largely dependent on the cell context. These data indicate that a deeper knowledge on the molecular mechanisms and biological effects of G-quadruplex structures is still needed to help developing new effective anticancer agents.
Linking of Antitumor trans NHC-Pt(II) Complexes to G-Quadruplex DNA Ligand for Telomeric Targeting
Bioconjugate Chemistry, 2016
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Future medicinal chemistry, 2016
Human telomeric DNA (hTelo), present at the ends of chromosomes to protect their integrity during cell division, comprises tandem repeats of the sequence d(TTAGGG) which is known to form a G-quadruplex secondary structure. This unique structural formation of DNA is distinct from the well-known helical structure that most genomic DNA is thought to adopt, and has recently gained prominence as a molecular target for new types of anticancer agents. In particular, compounds that can stabilize the intramolecular G-quadruplex formed within the human telomeric DNA sequence can inhibit the activity of the enzyme telomerase which is known to be upregulated in tumor cells and is a major contributor to their immortality. This provides the basis for the discovery and development of small molecules with the potential for selective toxicity toward tumor cells. This review summarizes the various families of small molecules reported in the literature that have telomeric quadruplex stabilizing proper...
Clinical and Experimental Medicine, 2018
The purpose of the present study was to investigate the in vitro and in vivo activity of PLX9486, a tyrosine kinase inhibitor (TKI) targeting both primary KIT exon 9 and 11 and secondary exon 17 and 18 mutations in gastrointestinal stromal tumors (GISTs). Imatinib, a potent inhibitor of mutated KIT, has revolutionized the clinical management of advanced, metastatic GIST. However, secondary resistance develops mainly through acquired mutations in KIT exons 13/14 or exons 17/18. Second-line sunitinib potently inhibits KIT exon 13/14 mutants but is ineffective against exon 17 mutations. In our study, PLX9486 demonstrated in vitro nanomolar potency in inhibiting the growth and KIT phosphorylation of engineered BaF3 cells transformed with KIT exon 17 mutations (p.D816V) and with the double KIT exon 11/17 mutations (p.V560G/D816V). The in vivo efficacy of PLX9486 was evaluated using two imatinib-resistant GIST patient-derived xenograft (PDX) models. In UZLX-GIST9 (KIT: p.P577del;W557LfsX5;D820G), PLX9486 100 mg/kg/day resulted in significant inhibition of proliferation. Pharmacodynamic analysis showed a pronounced reduction in mitogen-activated protein kinase (MAPK) activation and other downstream effects of the KIT signaling pathway but no significant effect on KIT Y703 and Y719 phosphorylation. Similarly, in MRL-GIST1 (KIT: p.W557_K558del;Y823D) PLX9486 treatment led to significant tumor regression and strong inhibition of MAPK activation. Interestingly, the inhibitory effect on MAPK activation was evident even after a single dose of PLX9486. In conclusion, PLX9486 showed anti-tumor efficacy in patient-derived imatinib-resistant GIST xenograft models, mainly through inhibition of KIT signaling. These preclinical efficacy data encourage further testing of PLX9486 in the clinical setting.
Journal of Medicinal Chemistry, 2012
Targeting of DNA secondary structures, such as G-quadruplexes, is now considered an appealing opportunity for drug intervention in anticancer therapy. So far, efforts made in the discovery of chemotypes able to target G-quadruplexes mainly succeeded in the identification of a number of polyaromatic compounds featuring end-stacking binding properties. Against this general trend, we were persuaded that the G-quadruplex grooves can recognize molecular entities with better drug-like and selectivity properties. From this idea, a set of small molecules was identified and the structural features responsible for G-quadruplex recognition were delineated. These compounds were demonstrated to have enhanced affinity and selectivity for the G-quadruplex over the duplex structure. Their ability to induce selective DNA damage at telomeric level and to induction of apoptosis and senescence on tumor cells is herein experimentally proven.
Journal of medicinal chemistry, 2018
Human pancreatic ductal adenocarcinoma (PDAC) involves the dysregulation of multiple signalling pathways. A novel approach to the treatment of PDAC is described, involving the targeting of cancer genes in PDAC pathways having over-representation of G-quadruplexes, using the tri-substituted naphthalene diimide quadruplex-binding compound 2,7-bis(3-morpholinopropyl)-4-((2-(pyrrolidin-1-yl)ethyl)amino) benzo[lmn][3,8] phenanthroline-1,3,6,8(2H,7H)-tetraone (CM03). This compound has been designed by computer modelling, is a potent inhibitor of cell growth in PDAC cell lines and has anti-cancer activity in PDAC models, with a superior profile compared to gemcitabine, a commonly used therapy. Whole-transcriptome RNA-seq methodology has been used to analyse the effects of this quadruplex-binding small molecule on global gene expression. This has revealed the down-regulation of a large number of genes, rich in putative quadruplex elements and involved in essential pathways of PDAC survival,...
Chemical targeting of G-quadruplexes in telomeres and beyond for molecular cancer therapeutics
The Journal of Antibiotics
G-quadruplexes (G4s) are higher-order structures formed by guanine-rich sequences of nucleic acids, such as the telomeric 5′-TTAGGG-3′/5′-UUAGGG-3′ repeats and those in gene regulatory regions. G4s regulate various biological events, including replication, transcription, and translation. Imbalanced G4 dynamics is associated with diseases, such as cancer and neurodegenerative diseases. Telomestatin is a natural macrocyclic compound derived from Streptomyces anulatus 3533-SV4. It interacts with the guanine quartet via π-π stacking and potently stabilizes G4. Because G4 stabilization at the telomeric repeat inhibits the telomere-synthesizing enzyme telomerase, telomestatin was originally identified as a telomerase inhibitor. Whereas non-toxic doses of telomestatin induce gradual shortening of telomeres and eventual crisis in human cancer cells, higher doses trigger prompt replication stress and DNA damage responses, resulting in acute cell death. Suppression of the transcription and translation of G4-containing genes is also implicated in the anticancer effects of telomestatin. Because telomestatin is rare, labile, and insoluble, synthetic oxazole telomestatin derivatives have been developed and verified for their therapeutic efficacies in preclinical cancer models. Furthermore, a variety of G4-stabilizing compounds have been reported as promising seeds for molecular cancer therapeutics. To improve the design of future clinical studies, it will be important to identify predictive biomarkers of drug efficacy.
Molecular Pharmacology, 2002
The telomerase complex is responsible for telomere maintenance and represents a promising cancer therapeutic target. We describe herein the antitelomerase and antitumor properties of a small-molecule compound designed by computer modeling to interact with and stabilize human G-quadruplex DNA, a structure that may form with telomeric DNA, thereby inhibiting access to telomerase. The 3,6,9-trisubstituted acridine 9-[4-(N,N-dimethylamino)phenylamino]-3,6-bis(3-pyrrolodinopropionamido) acridine (BRACO19) represents one of the most potent cell-free inhibitors of human telomerase yet described (50% inhibitory concentration of 115 Ϯ 18 nM). Moreover, in contrast to G-quadruplex interactive agents described previously, BRACO19 did not cause nonspecific acute cytotoxicity at similar concentrations to those required to completely inhibit telomerase activity. There exists a 90-fold differential (mean 50% inhibitory concentration for acute cell kill across seven human tumor cell lines of 10.6 Ϯ 0.7 M). The exposure of 21NT human breast cancer cells, which possess