title: Intracellular stability of 2'-OMe-4'-thioribonucleoside modified siRNA leads to long-term RNAi effect.
abstract: Chemically modified siRNAs are expected to have resistance toward nuclease degradation and good thermal stability in duplex formation for in vivo applications. We have recently found that 2'-OMe-4'-thioRNA, a hybrid chemical modification based on 2'-OMeRNA and 4'-thioRNA, has high hybridization affinity for complementary RNA and significant resistance toward degradation in human plasma. These results prompted us to develop chemically modified siRNAs using 2'-OMe-4'-thioribonucleosides for therapeutic application. Effective modification patterns were screened with a luciferase reporter assay. The best modification pattern of siRNA, which conferred duration of the gene-silencing effect without loss of RNAi activity, was identified. Quantification of the remaining siRNA in HeLa-luc cells using a Heat-in-Triton (HIT) qRT-PCR revealed that the intracellular stability of the siRNA modified with 2'-OMe-4'-thioribonucleosides contributed significantly to the duration of its RNAi activity.
authors.affiliation: Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-12, Nishi-6, Kita-ku, Sapporo 060-0812, Japan.
authors.forename: Mayumi
authors.initials: M
authors.lastname: Takahashi
authors.forename: Chisato
authors.initials: C
authors.lastname: Nagai
authors.forename: Hiroto
authors.initials: H
authors.lastname: Hatakeyama
authors.forename: Noriaki
authors.initials: N
authors.lastname: Minakawa
authors.forename: Hideyoshi
authors.initials: H
authors.lastname: Harashima
authors.forename: Akira
authors.initials: A
authors.lastname: Matsuda
mesh_terms: D017930:Genes, Reporter; D006367:HeLa Cells; D006801:Humans; D049409:Luciferases, Firefly / Q000235:genetics; D034622:RNA Interference; D020871:RNA Stability; D034741:RNA, Small Interfering / Q000737:chemistry* / Q000378:metabolism; D012260:Ribonucleases / Q000378:metabolism; D012263:Ribonucleosides / Q000737:chemistry; D013872:Thionucleosides / Q000737:chemistry*
chemical_list: D034741:RNA, Small Interfering; D012263:Ribonucleosides; D013872:Thionucleosides; D049409:Luciferases, Firefly; D012260:Ribonucleases