First- and second-generation antisense oligonucleotide inhibitors targeted against human c-raf kinase.
Following extensive screening of more than 50 antisense-designed phosphorothioate oligodeoxynucleotides targeted to human c-raf mRNA, one oligodeoxynucleotide (ISIS 5132/CGP 69846A) was identified as being the most potent inhibitor of c-raf gene expression both in vitro and in vivo. ISIS 5132 is a highly sequence-specific and target-specific inhibitor of c-raf mRNA and protein levels. c-raf inhibition results in dramatic alteration of downstream signalling events within the MAP kinase signalling pathway. Moreover, this oligodeoxynucleotide displays potent antitumour activity against a broad spectrum of tumour types in mouse models and has progressed to Phase I clinical trails. In an effort to identify potential back-up compounds to ISIS 5132, a variety of second-generation 2' sugar modifications have been evaluated for activity against c-raf in cell culture. We have identified a number of second-generation oligonucleotides with improved biophysical characteristics that result in enhanced activity against c-raf in cell culture. Activity enhancement was most pronounced for 2'-O-methoxyethyl-modified oligonucleotides and this modification also resulted in significantly improved antitumour activity in vivo.
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Isis Pharmaceuticals Inc., Department of Molecular Pharmacology, Carlsbad, CA 92008, USA.
D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D020319:Oligodeoxyribonucleotides, Antisense; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D019908:Proto-Oncogene Proteins c-raf / Q000037:antagonists & inhibitors* / Q000235:genetics; D013873:Thionucleotides / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D020319:Oligodeoxyribonucleotides, Antisense; D016376:Oligonucleotides, Antisense; D013873:Thionucleotides; C099587:ISIS 5132; D019908:Proto-Oncogene Proteins c-raf