The design of new antisense oligomers with improved binding affinity for targeted RNA, while still activating RNase H, is a major research area in medicinal chemistry. RNase H recognizes the RNADNA duplex and cleaves the complementary mRNA strand, providing the main mechanism by which antisense oligomers elicit their activities. It has been shown that configuration inversion at the C2' position of the DNA sugar moiety (arabinonucleic acid, ANA), combined with the substitution of the 2'OH group by a fluorine atom (2' F-ANA) increases the oligomer's binding affinity for targeted RNA. In the present study, we evaluated the antisense activity of mixed-backbone phosphorothioate oligomers composed of 2'-deoxy-2'-fluoro-β-D-arabinose and 2'-deoxyribose sugars (S-2' F-ANADNA chimeras). We determined their abilities to inhibit the protein expression and phosphorylation of Flk-1, a vascular endothelial growth factor receptor (VEGF), and VEGF biological effects on endothelial cell proliferation, migration, and platelet-activating factor synthesis. Treatment of endothelial cells with chimeric oligonucleotides reduced Flk-1 protein expression and phosphorylation more efficiently than with phosphorothioate antisenses (S-DNA). Nonetheless, these two classes of antisenses inhibited VEGF activities equally. Herein, we also demonstrated the capacity of the chimeric oligomers to elicit RNase H activity and their improved binding affinity for complementary RNA as compared with S-DNA.Key words: antisense DNA, 2' F-ANA nucleosides, mixed-backbone antisense, Flk-1, VEGF.
RNase H is responsible for the non-specific inhibition ofin vitrotranslation by 2′-O-alkyl chimeric oligonucleotides: high affinity or selectivity, a dilemma to design antisense oligomers
