title: Triple helix-forming oligonucleotides conjugated to indolocarbazole poisons direct topoisomerase I-mediated DNA cleavage to a specific site.
abstract: Topoisomerase I is an ubiquitous DNA-cleaving enzyme and an important therapeutic target in cancer chemotherapy for camptothecins as well as for indolocarbazole antibiotics such as rebeccamycin. To achieve a sequence-specific cleavage of DNA by topoisomerase I, a triple helix-forming oligonucleotide was covalently linked to indolocarbazole-type topoisomerase I poisons. The three indolocarbazole-oligonucleotide conjugates investigated were able to direct topoisomerase I cleavage at a specific site based upon sequence recognition by triplex formation. The efficacy of topoisomerase I-mediated DNA cleavage depends markedly on the intrinsic potency of the drug. We show that DNA cleavage depends also upon the length of the linker arm between the triplex-forming oligonucleotide and the drug. Based on a known structure of the DNA-topoisomerase I complex, a molecular model of the oligonucleotide conjugates bound to the DNA-topoisomerase I complex was elaborated to facilitate the design of a potent topoisomerase I inhibitor-oligonucleotide conjugate with an optimized linker between the two moieties. The resulting oligonucleotide-indolocarbazole conjugate at 10 nM induced cleavage at the triple helix site 2-fold more efficiently than 5 microM of free indolocarbazole, while the other drug-sensitive sites were not cleaved. The rational design of drug-oligonucleotide conjugates carrying a DNA topoisomerase poison may be exploited to improve the efficacy and selectivity of chemotherapeutic cancer treatments by targeting specific genes and reducing drug toxicity.
authors.affiliation: INSERM U524 and Laboratoire de Pharmacologie Antitumorale du Centre Oscar Lambret, IRCL, Place Verdun, 59045 Lille, France.
authors.forename: P B
authors.initials: PB
authors.lastname: Arimondo
authors.forename: C
authors.initials: C
authors.lastname: Bailly
authors.forename: A S
authors.initials: AS
authors.lastname: Boutorine
authors.forename: P
authors.initials: P
authors.lastname: Moreau
authors.forename: M
authors.initials: M
authors.lastname: Prudhomme
authors.forename: J S
authors.initials: JS
authors.lastname: Sun
authors.forename: T
authors.initials: T
authors.lastname: Garestier
authors.forename: C
authors.initials: C
authors.lastname: Hélène
mesh_terms: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D001483:Base Sequence; D002227:Carbazoles; D004247:DNA / Q000378:metabolism*; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D015195:Drug Design; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D007211:Indoles; D008958:Models, Molecular; D009841:Oligonucleotides / Q000138:chemical synthesis / Q000378:metabolism*; D013379:Substrate Specificity; D059004:Topoisomerase I Inhibitors
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D000970:Antineoplastic Agents; D002227:Carbazoles; D004791:Enzyme Inhibitors; D007211:Indoles; D009841:Oligonucleotides; D059004:Topoisomerase I Inhibitors; D004247:DNA; C053339:rebeccamycin; D004264:DNA Topoisomerases, Type I