Yuan Yuanyuan, Gong Faming, Cao Yang, Chen Weicai, Cheng Du, Shuai Xintao
J Biomed Nanotechnol. 2015 Apr;11(4):668-79. doi: 10.1166/jbn.2015.1966.
The gene silencing activity of small interfering RNA (siRNA) has led to their use as tools for target validation and as potential therapeutics for a variety of diseases. A major challenge is the development of vectors with high delivery efficiency and low toxicity. Although poly(ethylenimine) (PEI) has been regarded as the most promising polymeric vector for nucleic acid delivery, the nonbiodegradable structure greatly hinders its clinical application. In the present study, a diblock copolymer, PEG-PAsp(DIP-DETA), of poly(ethylene glycol) (PEG) and poly(L-aspartic acid) (PAsp) randomly grafted with pH-sensitive 2-(diisopropylamino)ethylamine (DIP) and diethylenetriamine (DETA) groups was synthesized via ring-opening polymerization and aminolysis reaction. Similar to polyethylenimine (PEI), the copolymer possesses a multiamine structure that not only allows effective siRNA complexation at neutral pH but also facilitates lysosomal release of siRNA via a proton buffering effect. Moreover, the poly(L-aspartic acid) backbone renders the vector biodegradability, which is not achievable with PEI. This novel polymeric vector can mediate effective intracellular siRNA delivery in various cancer cells. Consequently, the delivery of BCL-2 siRNA resulted in target gene silencing, inducing apoptosis and inhibiting the growth of cancer cells. These results show the potential of this non-PEI based polymeric vector with proton buffering capacity and biodegradability for siRNA delivery in cancer therapy.
小干扰RNA（siRNA）的基因沉默活性使其成为用于靶点验证的工具以及多种疾病的潜在治疗手段。一个主要挑战是开发具有高递送效率和低毒性的载体。尽管聚乙烯亚胺（PEI）被认为是用于核酸递送最有前景的聚合物载体，但其不可生物降解的结构极大地阻碍了其临床应用。在本研究中，通过开环聚合和氨解反应合成了一种聚乙二醇（PEG）与聚（L-天冬氨酸）（PAsp）的二嵌段共聚物PEG-PAsp（DIP-DETA），该共聚物随机接枝了pH敏感的2-（二异丙基氨基）乙胺（DIP）和二乙烯三胺（DETA）基团。与聚乙烯亚胺（PEI）类似，该共聚物具有多胺结构，不仅能在中性pH下实现有效的siRNA络合，还能通过质子缓冲效应促进siRNA从溶酶体释放。此外，聚（L-天冬氨酸）主链赋予载体生物可降解性，这是PEI无法实现的。这种新型聚合物载体可在各种癌细胞中介导有效的细胞内siRNA递送。因此，递送BCL-2 siRNA导致靶基因沉默，诱导细胞凋亡并抑制癌细胞生长。这些结果表明这种具有质子缓冲能力和生物可降解性的非PEI基聚合物载体在癌症治疗中用于siRNA递送的潜力。
