Yu Xiaolin, Xue Lu, Zhao Jing, Zhao Shuhua, Wu Daqing, Liu Hong Yan
Georgia Cancer Center, Augusta University, Augusta, GA 30912, USA.
Department of Pediatrics Hematology, The First Hospital of Jilin University, Changchun 130021, China.
Pharmaceutics. 2021 Dec 17;13(12):2182. doi: 10.3390/pharmaceutics13122182.
Despite the recent successes in siRNA therapeutics, targeted delivery beyond the liver remains the major hurdle for the widespread application of siRNA in vivo. Current cationic liposome or polymer-based delivery agents are restricted to the liver and suffer from off-target effects, poor clearance, low serum stability, and high toxicity. In this study, we genetically engineered a non-cationic non-viral tumor-targeted universal siRNA nanocarrier (MW 26 KDa). This protein nanocarrier consists of three function domains: a dsRNA binding domain (dsRBD) (from human protein kinase R) for any siRNA binding, 18-histidine for endosome escape, and two RGD peptides at the N- and C-termini for targeting tumor and tumor neovasculature. We showed that cloned dual-RGD-dsRBD-18his (dual-RGD) protein protects siRNA against RNases, induces effective siRNA endosomal escape, specifically targets integrin αβ expressing cells in vitro, and homes siRNA to tumors in vivo. The delivered siRNA leads to target gene knockdown in the cell lines and tumor xenografts with low toxicity. This multifunctional and biomimetic siRNA carrier is biodegradable, has low toxicity, is suitable for mass production by fermentation, and is serum stable, holding great potential to provide a widely applicable siRNA carrier for tumor-targeted siRNA delivery.
尽管近期在小干扰RNA（siRNA）疗法方面取得了成功，但在肝脏以外的靶向递送仍然是siRNA在体内广泛应用的主要障碍。目前基于阳离子脂质体或聚合物的递送剂局限于肝脏，且存在脱靶效应、清除率低、血清稳定性差和毒性高等问题。在本研究中，我们通过基因工程构建了一种非阳离子、非病毒的肿瘤靶向通用siRNA纳米载体（分子量26千道尔顿）。这种蛋白质纳米载体由三个功能结构域组成：一个用于结合任何siRNA的双链RNA结合结构域（dsRBD）（来自人类蛋白激酶R）、用于内体逃逸的18个组氨酸，以及在N端和C端的两个RGD肽，用于靶向肿瘤和肿瘤新生血管。我们发现，克隆的双RGD-dsRBD-18his（双RGD）蛋白可保护siRNA免受核糖核酸酶的降解，诱导有效的siRNA内体逃逸，在体外特异性靶向表达整合素αβ的细胞，并将siRNA在体内导向肿瘤。递送的siRNA可在细胞系和肿瘤异种移植物中导致靶基因敲低，且毒性较低。这种多功能且仿生的siRNA载体可生物降解，毒性低，适合通过发酵进行大规模生产，并且具有血清稳定性，极有可能为肿瘤靶向siRNA递送提供一种广泛适用的siRNA载体。
