美国麻省大学Anastasia Khvorova等研究人员合作通过扩展核酸骨架增强siRNA在体内的疗效。该研究于2024年8月1日在线发表于国际一流学术期刊《自然—生物技术》杂志上。

为了提高寡核苷酸的稳定性，研究人员报道了一种扩展核酸（exNA）的发现、合成及其特性表征，该核酸在核苷的5′-C和5′-OH之间插入了亚甲基。exNA的引入与常见的寡核苷酸合成方案和磷硫酸酯（PS）骨架兼容，能够抵抗3′和5′外切酶，并且在多个寡核苷酸位置上被耐受。

结合exNA的PS骨架相比于传统的PS骨架提高了对3′外切酶的抗性约32倍，相较于自然的磷酸二酯骨架提高了>1000倍，从而改善了小鼠系统性及脑部的组织暴露、组织积累和疗效。exNA所带来的改进的疗效和耐久性，可能使得在肝外组织中的治疗干预成为可能，包括小干扰RNA（siRNA）、CRISPR引导RNA、反义寡核苷酸、mRNA和tRNA等其他寡核苷酸。

据悉，治疗性siRNA需要糖基和骨架修饰以抑制核酸酶降解。然而，目前临床上使用的唯一骨架化学修饰——PS，可能对靶向肝外组织不够有效。

附：英文原文

Title: Enhancing siRNA efficacy in vivo with extended nucleic acid backbones

Author: Yamada, Ken, Hariharan, Vignesh N., Caiazzi, Jillian, Miller, Rachael, Ferguson, Chantal M., Sapp, Ellen, Fakih, Hassan H., Tang, Qi, Yamada, Nozomi, Furgal, Raymond C., Paquette, Joseph D., Biscans, Annabelle, Bramato, Brianna M., McHugh, Nicholas, Summers, Ashley, Lochmann, Clemens, Godinho, Bruno M. D. C., Hildebrand, Samuel, Jackson, Samuel O., Echeverria, Dimas, Hassler, Matthew R., Alterman, Julia F., DiFiglia, Marian, Aronin, Neil, Khvorova, Anastasia

Issue&Volume: 2024-08-01

Abstract: Therapeutic small interfering RNA (siRNA) requires sugar and backbone modifications to inhibit nuclease degradation. However, metabolic stabilization by phosphorothioate (PS), the only backbone chemistry used clinically, may be insufficient for targeting extrahepatic tissues. To improve oligonucleotide stabilization, we report the discovery, synthesis and characterization of extended nucleic acid (exNA) consisting of a methylene insertion between the 5′-C and 5′-OH of a nucleoside. exNA incorporation is compatible with common oligonucleotide synthetic protocols and the PS backbone, provides stabilization against 3′ and 5′ exonucleases and is tolerated at multiple oligonucleotide positions. A combined exNA–PS backbone enhances resistance to 3′ exonuclease by ~32-fold over the conventional PS backbone and by >1,000-fold over the natural phosphodiester backbone, improving tissue exposure, tissue accumulation and efficacy in mice, both systemically and in the brain. The improved efficacy and durability imparted by exNA may enable therapeutic interventions in extrahepatic tissues, both with siRNA and with other oligonucleotides such as CRISPR guide RNA, antisense oligonucleotides, mRNA and tRNA.

DOI: 10.1038/s41587-024-02336-7

Source: https://www.nature.com/articles/s41587-024-02336-7