Mesyl phosphoramidate backbone modified antisense oligonucleotides targeting miR-21 with enhanced in vivo therapeutic potency

Abstract

The design of modified oligonucleotides that combine in one molecule several therapeutically beneficial properties still poses a major challenge. Recently a new type of modified mesyl phosphoramidate (or µ-) oligonucleotide was described that demonstrates high affinity to RNA, exceptional nuclease resistance, efficient recruitment of RNase H, and potent inhibition of key carcinogenesis processes in vitro. Herein, using a xenograft mouse tumor model, it was demonstrated that microRNA miR-21–targeted µ-oligonucleotides administered in complex with folate-containing liposomes dramatically inhibit primary tumor growth via long-term down-regulation of miR-21 in tumors and increase in biosynthesis of miR-21–regulated tumor suppressor proteins. This antitumoral effect is superior to the effect of the corresponding phosphorothioate. Peritumoral administration of µ-oligonucleotide results in its rapid distribution and efficient accumulation in the tumor. Blood biochemistry and morphometric studies of internal organs revealed no pronounced toxicity of µ-oligonucleotides. This new oligonucleotide class provides a powerful tool for antisense technology.

Towards next generation antisense oligonucleotides: mesylphosphoramidate modification improves therapeutic index and duration of effect of gapmer antisense oligonucleotides

“…The MsPA modifcation was recently reported by Stetsenko as an alternate for PS in uniform DNA ASOs targeting miR-21 ( 13 ). Uniform DNA MsPA oligonucleotides administered in complex with folate-containing liposomes demonstrated RNaseH1-mediated inhibition of primary tumor growth by downregulating miR-21 in tumors and increased biosynthesis of miR-21–regulated tumor suppressor proteins ( 12 ). Peritumoral administration of MsPA DNA ASOs resulted in efficient accumulation in the tumor.…”

“…The mesylphosphoramidate (MsPA) linkage was recently reported by Stetsenko as an alternate to PS for RNaseH1-mediated knock down of micro RNA targets and to modulate mRNA splicing ( 12–14 ). In the MsPA linkage, one of the non-bridging oxygen atoms in the phosphodiester linkage is replaced with methanesulfonylamido group (Figure 1A ).…”

The regulatory roles of microRNAs toward pathogenesis and treatments in Huntington's disease

“…Therefore, PS and 2’-OMe RNA techniques are also broadly used as miRNA antisense inhibitors to block the functions of miRNAs [ 86 , 88 ]. Even more, new modified mesyl phosphoramidate RNA targeting to miRNAs has shown more efficient to block miRNA functions [ 89 ]. These results suggest the increase of miRNA stability to prolong half-life is a critical step to apply miRNA therapy, and synthetic biology would also play an important role for this application.…”

Novel Lipid-Oligonucleotide Conjugates Containing Long-Chain Sulfonyl Phosphoramidate Groups: Synthesis and Biological Properties

“…The obtained lipid-oligonucleotide conjugates (LONs) can be conveniently isolated by the usual C18 reverse-phased HPLC, due to significant difference in retention times with unmodified oligonucleotides (see Supplementary Materials) for HPLC profiles and ESI-MS spectra). Our preliminary data have shown that such lipophilic groups are fully compatible with other phosphate group modifications such as phosphorothioate, mesyl phosphoramidate [27,37,38] and phosphoryl guanidine [39].…”