Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Biomaterials. 2014 Sep;35(27):7887-95. doi: 10.1016/j.biomaterials.2014.05.041. Epub 2014 Jun 13.
For small interfering RNA (siRNA)-based cancer therapies, we report an actively-targeted and stabilized polyion complex micelle designed to improve tumor accumulation and cancer cell uptake of siRNA following systemic administration. Improvement in micelle stability was achieved using two stabilization mechanisms; covalent disulfide cross-linking and non-covalent hydrophobic interactions. The polymer component was designed to provide disulfide cross-linking and cancer cell-targeting cyclic RGD peptide ligands, while cholesterol-modified siRNA (Chol-siRNA) provided additional hydrophobic stabilization to the micelle structure. Dynamic light scattering confirmed formation of nano-sized disulfide cross-linked micelles (<50 nm in diameter) with a narrow size distribution. Improved stability of Chol-siRNA-loaded micelles (Chol-siRNA micelles) was demonstrated by resistance to both the dilution in serum-containing medium and counter polyion exchange with dextran sulfate, compared to control micelles prepared with Chol-free siRNA (Chol-free micelles). Improved stability resulted in prolonged blood circulation time of Chol-siRNA micelles compared to Chol-free micelles. Furthermore, introduction of cRGD ligands onto Chol-siRNA micelles significantly facilitated accumulation of siRNA in a subcutaneous cervical cancer model following systemic administration. Ultimately, systemically administered cRGD/Chol-siRNA micelles exhibited significant gene silencing activity in the tumor, presumably due to their active targeting ability combined with the enhanced stability through both hydrophobic interactions of cholesterol and disulfide cross-linking.
对于基于小干扰 RNA (siRNA) 的癌症治疗，我们报告了一种主动靶向和稳定的聚离子复合物胶束，旨在改善系统给药后 siRNA 在肿瘤中的积累和癌细胞摄取。通过两种稳定机制实现了胶束稳定性的提高；二硫键交联和非共价疏水相互作用。聚合物组分的设计提供了二硫键交联和癌细胞靶向环 RGD 肽配体，而胆固醇修饰的 siRNA（Chol-siRNA）为胶束结构提供了额外的疏水稳定性。动态光散射证实形成了纳米尺寸的二硫键交联胶束（<50nm 直径），具有窄的粒径分布。与用无胆固醇 siRNA（Chol-free micelles）制备的对照胶束相比，载有 Chol-siRNA 的胶束（Chol-siRNA 胶束）的稳定性得到了改善，表现在对含血清介质中稀释的抵抗力以及与硫酸葡聚糖的反聚离子交换方面。Chol-siRNA 胶束的稳定性提高导致其血液循环时间延长与 Chol-free 胶束相比。此外，将 cRGD 配体引入 Chol-siRNA 胶束后，在系统给药后显著促进了 siRNA 在皮下宫颈癌模型中的积累。最终，系统给予的 cRGD/Chol-siRNA 胶束在肿瘤中表现出显著的基因沉默活性，这可能是由于其主动靶向能力与胆固醇的疏水相互作用和二硫键交联增强的稳定性相结合。
