1. Sequence-specific targeting of IGF-I and IGF-IR genes by camptothecins.
- Author
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Oussedik K, François JC, Halby L, Senamaud-Beaufort C, Toutirais G, Dallavalle S, Pommier Y, Pisano C, and Arimondo PB
- Subjects
- Animals, Antineoplastic Agents, Phytogenic, Base Sequence, Binding Sites, Cell Line, Enzyme Inhibitors, Humans, Insulin-Like Growth Factor I genetics, Promoter Regions, Genetic, Rats, Receptor, IGF Type 1 genetics, Camptothecin pharmacology, DNA Damage drug effects, Insulin-Like Growth Factor I antagonists & inhibitors, Receptor, IGF Type 1 antagonists & inhibitors, Topoisomerase I Inhibitors
- Abstract
We and others have clearly demonstrated that a topoisomerase I (Top1) inhibitor, such as camptothecin (CPT), coupled to a triplex-forming oligonucleotide (TFO) through a suitable linker can be used to cause site-specific cleavage of the targeted DNA sequence in in vitro models. Here we evaluated whether these molecular tools induce sequence-specific DNA damage in a genome context. We targeted the insulin-like growth factor (IGF)-I axis and in particular promoter 1 of IGF-I and intron 2 of type 1 insulin-like growth factor receptor (IGF-IR) in cancer cells. The IGF axis molecules represent important targets for anticancer strategies, because of their central role in oncogenic maintenance and metastasis processes. We chemically attached 2 CPT derivatives to 2 TFOs. Both conjugates efficiently blocked gene expression in cells, reducing the quantity of mRNA transcribed by 70-80%, as measured by quantitative RT-PCR. We confirmed that the inhibitory mechanism of these TFO conjugates was mediated by Top1-induced cleavage through the use of RNA interference experiments and a camptothecin-resistant cell line. In addition, induction of phospho-H2AX foci supports the DNA-damaging activity of TFO-CPT conjugates at specific sites. The evaluated conjugates induce a specific DNA damage at the target gene mediated by Top1.
- Published
- 2010
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