Arabinonucleic Acids: 2′-Stereoisomeric Modulators of siRNA Activity

We have investigated, for the first time, short interfering duplexes containing arabinonucleotides (ANA; the 2′-stereoisomer of RNA), as well as combinations of ANA with RNA, and their 2′-fluorinated derivatives 2F-ANA and/or 2′F-RNA. The results show that ANA is especially well accommodated in the sense strand of small interfering RNA (siRNA) duplexes, which can be extensively modified with little effect on potency. Furthermore, combining ANA with RNA and 2′F-ANA in siRNA passenger strands, particularly in patterns that bias duplex thermal stability, produces duplexes with similar (and sometimes enhanced) potency compared with native siRNA. Effective patterns of modification were identified against firefly luciferase screens in HeLa cells and then applied to knockdown of down-regulated in renal cell carcinoma (DRR), a novel and clinically tractable target for the treatment of glioblastoma.