title: MicroRNA-like off-target transcript regulation by siRNAs is species specific.
abstract: siRNAs mediate sequence-specific gene silencing in cultured mammalian cells but also silence unintended transcripts. Many siRNA off-target transcripts match the guide-strand "seed region," similar to the way microRNAs match their target sites. The extent to which this seed-matched, microRNA-like, off-target silencing affects the specificity of therapeutic siRNAs in vivo is currently unknown. Here, we compare microRNA-like off-target regulations in mouse liver in vivo with those seen in cell culture for a series of therapeutic candidate siRNAs targeting Apolipoprotein B (APOB). Each siRNA triggered regulation of consistent microRNA-like off-target transcripts in mouse livers and in cultured mouse liver tumor cells. In contrast, there was only random overlap between microRNA-like off-target transcripts from cultured human and mouse liver tumor cells. Therefore, siRNA therapeutics may trigger microRNA-like silencing of many unintended targets in vivo, and the potential toxicities caused by these off-target gene regulations cannot be accurately assessed in rodent models.
authors.affiliation: Rosetta Inpharmatics LLC, Seattle, Washington 98109, USA.
authors.forename: Julja
authors.initials: J
authors.lastname: Burchard
authors.forename: Aimee L
authors.initials: AL
authors.lastname: Jackson
authors.forename: Vladislav
authors.initials: V
authors.lastname: Malkov
authors.forename: Rachel H V
authors.initials: RH
authors.lastname: Needham
authors.forename: Yejun
authors.initials: Y
authors.lastname: Tan
authors.forename: Steven R
authors.initials: SR
authors.lastname: Bartz
authors.forename: Hongyue
authors.initials: H
authors.lastname: Dai
authors.forename: Alan B
authors.initials: AB
authors.lastname: Sachs
authors.forename: Peter S
authors.initials: PS
authors.lastname: Linsley
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D001055:Apolipoproteins B / Q000235:genetics*; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D020869:Gene Expression Profiling; D020868:Gene Silencing; D006801:Humans; D051379:Mice; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism*; D012641:Selection, Genetic; D013045:Species Specificity; D014158:Transcription, Genetic
chemical_list: D020413:3' Untranslated Regions; D001055:Apolipoproteins B; D035683:MicroRNAs; D034741:RNA, Small Interfering