title: Exploring the cellular activity of camptothecin-triple-helix-forming oligonucleotide conjugates.
abstract: Topoisomerase I is a ubiquitous DNA-cleaving enzyme and an important therapeutic target in cancer chemotherapy for camptothecins (CPTs). These drugs stimulate DNA cleavage by topoisomerase I but exhibit little sequence preference, inducing toxicity and side effects. A convenient strategy to confer sequence specificity consists of the linkage of topoisomerase poisons to DNA sequence recognition elements. In this context, triple-helix-forming oligonucleotides (TFOs) covalently linked to CPTs were investigated for the capacity to direct topoisomerase I-mediated DNA cleavage in cells. In the first part of our study, we showed that these optimized conjugates were able to regulate gene expression in cells upon the use of a Photinus pyralis luciferase reporter gene system. Furthermore, the formation of covalent topoisomerase I/DNA complexes by the TFO-CPT conjugates was detected in cell nuclei. In the second part, we elucidated the molecular specificity of topoisomerase I cleavage by the conjugates by using modified DNA targets and in vitro cleavage assays. Mutations either in the triplex site or in the DNA duplex receptor are not tolerated; such DNA modifications completely abolished conjugate-induced cleavage all along the DNA. These results indicate that these conjugates may be further developed to improve chemotherapeutic cancer treatments by targeting topoisomerase I-induced DNA cleavage to appropriately chosen genes.
authors.affiliation: UMR 5153 CNRS-Muséum National d'Histoire Naturelle USM0503, INSERM UR565, 43 rue Cuvier, 75231 Paris Cédex 05, France. arimondo@mnhn.fr
authors.forename: Paola B
authors.initials: PB
authors.lastname: Arimondo
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Thomas
authors.forename: Kahina
authors.initials: K
authors.lastname: Oussedik
authors.forename: Brigitte
authors.initials: B
authors.lastname: Baldeyrou
authors.forename: Christine
authors.initials: C
authors.lastname: Mahieu
authors.forename: Ludovic
authors.initials: L
authors.lastname: Halby
authors.forename: Dominique
authors.initials: D
authors.lastname: Guianvarc'h
authors.forename: Amélie
authors.initials: A
authors.lastname: Lansiaux
authors.forename: Sidney M
authors.initials: SM
authors.lastname: Hecht
authors.forename: Christian
authors.initials: C
authors.lastname: Bailly
authors.forename: Carine
authors.initials: C
authors.lastname: Giovannangeli
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000494:pharmacology*; D001483:Base Sequence; D002166:Camptothecin / Q000737:chemistry / Q000494:pharmacology*; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism*; D004264:DNA Topoisomerases, Type I / Q000187:drug effects* / Q000378:metabolism; D048888:Fireflies / Q000201:enzymology; D015870:Gene Expression / Q000187:drug effects; D017930:Genes, Reporter / Q000235:genetics; D006801:Humans; D008156:Luciferases / Q000032:analysis / Q000235:genetics; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000737:chemistry / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D009841:Oligonucleotides; D004247:DNA; D008156:Luciferases; D004264:DNA Topoisomerases, Type I; D002166:Camptothecin