Abstract PR14: Potent knock down of lncRNAs in vitro and in vivo with antisense LNA™ GapmeRs

Abstract

Abstract Exiqon develops strategies for the optimal design of single stranded LNA™-enhanced antisense oligonucleotides (ASOs, also known as LNA™ GapmeRs) that catalyze RNaseH dependent degradation of target mRNAs and long non-coding RNAs (lncRNA). We have developed an empirically derived design algorithm to provide ASOs that achieve potent target knockdown with a high hit-rate. We describe the latest improvements to the design algorithm, including the incorporation of alignments to both spliced and unspliced transcriptomes in the Ensembl database, to provide maximal target specificity. Many lncRNAs are nuclear retained or have long residence time in the nucleus. This makes them hard to target by RNAi based methods. However since RNaseH is almost exclusively present in the nucleus nuclear RNAs are expected to be particularly sensitive LNA™ GapmeR targets. We have tested LNA™ GapmeRs to knockdown multiple different RNA targets in vitro – including mRNA and lncRNA targets residing in either cytoplasmic or nuclear compartments. Our results demonstrate that all of these targets were equally efficiently silenced irrespective of the type of RNA target and its subcellular localization. We also report highly efficient and long lasting knockdown of a nuclear retained lncRNA in a broad range of tissues in mice subjected to systemic adminstration of a LNA™ GapmeR. LNA GapmeRs are therefore excellent tools for lncRNA loss of function analysis in vitro and in vivo and provide an excellent platform for therapeutic targeting of lncRNA. Risk of hybridization based off-target activity with gapmers has traditionally been considered to be low. However in a recent publication1 it was shown that unless properly designed antisense off-target activity with gapmers can be quite significant. Surprisingly, particularly sensitive off-targets were frequently localized in introns of primary transcripts causing significant reduction of the amount of mature spliced mRNAs. Since RNaseH is confined to the nucleus we therefore speculated that the true target of gapmers might be unspliced primary transcripts in the nucleus rather than the spliced mature transcripts that are exported to the cytoplasm. We present data showing that intron targeting LNA GapmeRs often provide highly potent knockdown of the mature spliced RNA. These results have profound implications on therapeutic gapmer design. 1. Kamola PJ, Nucl. Acids Res. 2015, pii: gkv857 This abstract is also presented as Poster B45. Citation Format: Johnathan Lai, Asli Ozen, Peter Mouritzen, Niels Tolstrup, Niels Montano Frandsen. Potent knock down of lncRNAs in vitro and in vivo with antisense LNA™ GapmeRs. [abstract]. In: Proceedings of the AACR Special Conference on Noncoding RNAs and Cancer: Mechanisms to Medicines ; 2015 Dec 4-7; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2016;76(6 Suppl):Abstract nr PR14.