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: Paola B Arimondo, Craig J Thomas, Kahina Oussedik, Brigitte Baldeyrou, Christine Mahieu, Ludovic Halby, Dominique Guianvarc'h, Amélie Lansiaux, Sidney M Hecht, Christian Bailly, Carine Giovannangeli
• Journal: Molecular and cellular biology (Mol Cell Biol) Vol. 26 Issue 1 Pg. 324-33 (Jan 2006) ISSN: 0270-7306 [Print] United States
• PMID: 16354702 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Antineoplastic Agents, Phytogenic
• Oligonucleotides
• DNA
• Luciferases
• DNA Topoisomerases, Type I
• Camptothecin

Topics

• Antineoplastic Agents, Phytogenic (chemistry, pharmacology)
• Base Sequence
• Camptothecin (chemistry, pharmacology)
• Cells, Cultured
• DNA (metabolism)
• DNA Topoisomerases, Type I (drug effects, metabolism)
• Fireflies (enzymology)
• Gene Expression (drug effects)
• Genes, Reporter (genetics)
• Humans
• Luciferases (analysis, genetics)
• Molecular Sequence Data
• Oligonucleotides (chemistry, pharmacology)
• Tumor Cells, Cultured