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Sequence‐specific targeting of IGF‐I and IGF‐IR genes by camptothecins
Author(s) -
Oussedik Kahina,
François JeanChristophe,
Halby Ludovic,
SenamaudBeaufort Catherine,
Toutirais Géraldine,
Dallavalle Sabrina,
Pommier Yves,
Pisano Claudio,
Arimondo Paola B.
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.09-132324
Subject(s) - camptothecin , oligonucleotide , gene , biology , dna , topoisomerase , cleavage (geology) , intron , microbiology and biotechnology , chemistry , genetics , biochemistry , paleontology , fracture (geology)
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 insulinlike 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.—Oussedik, K., François, J.‐C, Halby, L., Senamaud‐Beaufort, C, Toutirais, G., Dallavalle, S., Pommier, Y., Pisano, C, Arimondo, P. B. Sequence‐specific targeting of IGF‐I and IGF‐IR genes by camptothecins. FASEB J. 24, 2235–2244 (2010). www.fasebj.org