Efficacy of microRNA silencing by lipid-conjugated double-stranded antisense oligonucleotides

MicroRNAs (miRNAs) are important therapeutic targets for intractable diseases and antisense oligonucleotides that silence microRNA (antagomirs) have been developed for clinical applications. Although conjugation of ligands to antagomirs is a promising means of delivering them to target tissues and cells, the efficacy of these constructs is yet to be optimized. In this study, we designed a novel antagomir construct that comprise an antagomir strand and its complementary RNA strand. We were then able to indirectly conjugate ligands to this double-stranded antagomir via the complementary RNA strand. We then used singleor doublestranded antagomirs to examine effects of ligand type, conjugation site, or chemical modifications of the antagomir strand on miRNA silencing in vitro. We found that indirect conjugation of cholesterol ligand to a double-stranded antagomir produced a construct with comparable miRNA-silencing efficacy as that of a single-stranded antagomir directly conjugated with the ligand. Our findings support application of this technology for the therapeutic regulation of miRNA.