Characterization of a Triple Helix-specific Ligand

Pilch, Daniel S.; Waring, Michael J.; Sun, Jian‐Sheng; Rougée, Michel; Nguyen, Chi-Hung; Bisagni, Émile; Garestier, Thérèse; Hélène, Claude

doi:10.1006/jmbi.1993.1440

Cited by 77 publications

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“…Because no structural data are available on triple helix-ligand complexes, not much is known about the interactions that direct specific intercalation into triple helices. BPI derivatives have been shown to intercalate between T⅐AϫT base triplets by excitation fluorescence energy transfer from base triplets to ligands (16,25) and by linear and circular dichroism (26). By comparing the effects of various substituents of BPI on triple helix stabilization, molecular modeling has proposed two models of intercalation for BePI and BgPI molecules in triple helices (27).…”

Section: And References Therein)mentioning

confidence: 99%

Rational design of a triple helix-specific intercalating ligand

Escudé

Nguyen

Kukreti

et al. 1998

Proc. Natl. Acad. Sci. U.S.A.

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107

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Section: And References Therein)mentioning

confidence: 99%

Rational design of a triple helix-specific intercalating ligand

Escudé

Nguyen

Kukreti

et al. 1998

Proc. Natl. Acad. Sci. U.S.A.

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107

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Section: Dna Binding -Viscometric Studiesmentioning

confidence: 99%

“…Viscosity experiments were carried out in an Ostwald-type capillary viscometer maintained at 25.0 ± 0.1°C by immersion in a circulating water bath (Pilch et al, 1993;Suh and Chaires, 1995). Aliquots of concentrated drug solution were added directly to the viscometer containing a CT-DNA solution [1.3 ml of 250 µM(bp)] in phosphate buffer to give [total drug]/[DNA(bp)] molar ratios of 0.075, 0.15, 0.225 and 0.30.…”

Section: Dna Binding -Viscometric Studiesmentioning

confidence: 99%

Cellular uptake, cytotoxicity and DNA-binding studies of the novel imidazoacridinone antineoplastic agent C1311

et al. 1999

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Summary C1311 is a novel therapeutic agent with potent activity against experimental colorectal cancer that has been selected for entry into clinical trial. The compound has previously been shown to have DNA-binding properties and to inhibit the catalytic activity of topoisomerase II. In this study, cellular uptake and mechanisms by which C1311 interacts with DNA and exerts cytotoxic effects in intact colon carcinoma cells were investigated. The HT29 colon cancer cell line was chosen to follow cellular distribution of C1311 over a time course of 24 h at drug concentrations that just inhibited cell proliferation by 50% or 100%. Nuclear uptake of C1311 and co-localization with lysosomal or mitochondrial dyes was examined by fluorescence microscopy and effects on these cellular compartments were determined by measurement of acid phosphatase levels, rhodamine 123 release or DNA-binding behaviour. The strength and mode of DNA binding was established by thermal melting stabilization, direct titration and viscometric studies of host duplex length. The onset of apoptosis was followed using a TUNEL assay and DNA-fragmentation to determine a causal relationship of cell death. Growth inhibition of HT29 cells by C1311 was concomitant with rapid drug accumulation in nuclei and in this context we showed that the compound binds to duplex DNA by intercalation, with likely A/T sequence-preferential binding. Drug uptake was also seen in lysosomes, leading to lysosomal rupture and a marked increase of acid phosphatase activity 8 h after exposure to C1311 concentrations that effect total growth inhibition. Moreover, at these concentrations lysosomal swelling and breakdown preceded apoptosis, which was not evident up to 24 h after exposure to drug. Thus, the lysosomotropic effect of C1311 appears to be a novel feature of this anticancer agent. As it is unlikely that C1311-induced DNA damage alone would be sufficient for cytotoxic activity, lysosomal rupture may be a critical component for therapeutic efficacy.Keywords: C1311; HT29 cells; colorectal cancer; cytotoxicity; DNA intercalation; lysosomes 367British Journal of Cancer (1999) 81(2), 367-375 © 1999 Cancer Research Campaign Article no. bjoc.1999 Received MATERIALS AND METHODS Materials/DrugsThe 5-(ω-aminoalkyl)amino-8-hydroxyimidazoacridinone C1311 (Figure 1) was synthesized at the Technical University of Gdansk, as described elsewhere (Cholody et al, 1990(Cholody et al, , 1992. Stock solutions were prepared in dimethyl sulphoxide (DMSO) or normal saline. Aqueous solutions were prepared in polystyrene tubes to minimize adsorption effects and quantified by spectrophotometry. Hoechst 33258 dye (Sigma-Aldrich Ltd) was used as a control ligand for viscometric studies and quantified using ε 338 = 42 000 M -1 cm -1 (Loontiens et al, 1990). All DNA binding experiments were performed in aqueous phosphate buffer (10 mM NaH 2 PO 4 /Na 2 HPO 4 , 1 mM Na 2 EDTA, pH 7.00 ± 0.01). Doublestranded calf thymus DNA (CT-DNA, type-I [Sigma-Aldrich Ltd.]) was sonicated and purified using a publ...

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“…Two distinct categories of nucleic acid-binding ligand have recently been reported that selectively stabilize triplex formation over duplex, probably by direct binding to triplex regions. The first category includes several planar, fused-ring polycyclic compounds possessing large surface areas, such as a benzo[e]pyridoindole derivative (22)(23)(24), methylene blue (25), ethidium (26), and the alkaloid coralyne (27). The second category uses unfused aromatic naphthylquinolines with extended alkylamine cationic side chains, which have been shown by molecular modeling to at least stack partially with all six bases in a triplet intercalation site (28,29).…”

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A molecular anchor for stabilizing triple-helical DNA.

Fox

Polucci

Jenkins

et al. 1995

Proc. Natl. Acad. Sci. U.S.A.

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Molecular modeling has been used to predict that 2,6-disubstituted amidoanthraquinones, and not the 1,4 series, should preferentially interact with and stabilize triplestranded DNA structures over duplex DNA. This is due to marked differences in the nature of chromophore-base stacking and groove accessibility for the two series. A DNA footprinting method that monitors the extent of protection from DNase I cleavage on triplex formation has been used to examine the effects of a number of synthetic isomer compounds in the 1,4 and 2,6 series. The experimental results are in accord with the predicted behavior and confirm that the 1,4 series bind preferentially to double-rather than triplestranded DNA, whereas the isomeric 2,6 derivatives markedly favor binding to triplex DNA.The DNA double helix can, subject to several sequence restrictions, interact with a third strand of oligonucleotide or polynucleotide to form a triple-stranded helix, the DNA triplex (1-4). There are two principal categories of triplex that are defined by these sequence restrictions. In one, a third pyrimidine-rich strand interacts by means of Hoogsteen hydrogen bonds with a stretch of purines in the target duplex and is oriented parallel to it. This involves T-AT and C+*GC triplet base interactions, with a requirement for a low pH in the latter instance due to necessary protonation of the third-strand cytosine to enable the formation of two hydrogen bonds to a guanine base. The second category has a third purine-rich strand, now oriented anti-parallel to a purine stretch in the duplex target, involving A-TA and GCG base interactions. These intermolecular triplexes have aroused considerable interest as potential inhibitors of the expression of particular genes, since a sequence of either third-strand pyrimidines or purines, when -16-18 base pairs long, can be sufficient to be unique for recognition and binding to defined single sites in a genome. A number of experiments have now been reported that demonstrate the feasibility of this concept. Specific inhibition of transcription has been shown by means of triplex formation at poly(purine/pyrimidine) sites in promoter sequences [for example, in the promoter of the a subunit of the interleukin 2 receptor to the NF-KB transcription factor (5, 6), in the c-myc promoter (7-9), and to a Spl transcriptional activator site in the Ha-ras gene (10)]. Triplex formation can also directly inhibit transcription by blocking RNA polymerase (11, 12).Association of a third strand with a duplex is a thermodynamically weaker and a kinetically slower interaction (13-16) than duplex formation itself. Covalent attachment of intercalating groups such as acridines or ellipticines, mostly to the 5' end of the third strand, has been used to provide enhanced triplex stability, with the chromophore probably being intercalated within a duplex site close to the duplex-triplex junction (3,5,17). Functionalization with a photoreactive psoralen has a similar effect, although in this instance UV activation leads to covalent...

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Characterization of a Triple Helix-specific Ligand

Cited by 77 publications

References 0 publications

Rational design of a triple helix-specific intercalating ligand

Rational design of a triple helix-specific intercalating ligand

Cellular uptake, cytotoxicity and DNA-binding studies of the novel imidazoacridinone antineoplastic agent C1311

A molecular anchor for stabilizing triple-helical DNA.

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