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.
|Titolo:||Sequence-specific targeting of IGF-I and IGF-IR genes by camptothecins|
|Parole Chiave:||DNA regulation ; specific DNA cleavage ; topoisomerase I poisons ; triplex-forming oligonucleotides ; anticancer agents|
|Settore Scientifico Disciplinare:||Settore CHIM/06 - Chimica Organica|
|Data di pubblicazione:||lug-2010|
|Digital Object Identifier (DOI):||10.1096/fj.09-132324|
|Appare nelle tipologie:||01 - Articolo su periodico|