Department of Physical Pharmaceutics, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan.
Mol Pharm. 2012 Sep 4;9(9):2591-604. doi: 10.1021/mp300188f. Epub 2012 Aug 9.
We previously reported that of the various polyamidoamine (PAMAM) STARBURST dendrimer (generation 3, G3) (dendrimer) conjugates with cyclodextrins (CyDs), the dendrimer (G3) conjugate with α-CyD having an average degree of substitution of 2.4 (α-CDE (G3)) has the greatest potential for a novel carrier for siRNA in vitro and in vivo. To improve the siRNA transfer activity and the lack of target specificity of α-CDE (G3), we prepared folate-polyethylene glycol (PEG)-appended α-CDEs (G3) (Fol-PαCs) with various degrees of substitution of folate (DSF) and evaluated their siRNA transfer activity to folate receptor (FR)-overexpressing cancer cells in vitro and in vivo. Of the three Fol-PαCs (G3, DSF 2, 4 and 7), Fol-PαC (G3, DSF 4) had the highest siRNA transfer activity in KB cells (FR-positive). Fol-PαC (G3, DSF 4) was endocytosed into KB cells through FR. No cytotoxicity of the siRNA complex with Fol-PαC (G3, DSF 4) was observed in KB cells (FR-positive) or A549 cells (FR-negative) up to the charge ratio of 100/1 (carrier/siRNA). In addition, the siRNA complex with Fol-PαC (G3, DSF 4) showed neither interferon response nor inflammatory response. Importantly, the siRNA complex with Fol-PαC (G3, DSF 4) tended to show the in vivo RNAi effects after intratumoral injection and intravenous injection in tumor cells-bearing mice. The FITC-labeled siRNA and TRITC-labeled Fol-PαC (G3, DSF 4) were actually accumulated in tumor tissues after intravenous injection in the mice. In conclusion, the present results suggest that Fol-PαC (G3, DSF 4) could potentially be used as a FR-overexpressing cancer cell-selective siRNA delivery carrier in vitro and in vivo.
我们之前报道过，在各种聚酰胺-胺（PAMAM）星形支化聚合物（第三代，G3）（树枝状聚合物）与环糊精（CyD）的缀合物中，具有平均取代度为 2.4 的 α-CyD 树枝状聚合物（G3）缀合物（α-CDE（G3））具有作为新型 siRNA 载体在体外和体内的最大潜力。为了提高 siRNA 转移活性和 α-CDE（G3）缺乏靶向特异性，我们用不同叶酸取代度（DSF）制备了叶酸-聚乙二醇（PEG）接枝的 α-CDEs（G3）（Fol-PαCs），并评价了它们在体外和体内向叶酸受体（FR）过表达癌细胞的 siRNA 转移活性。在三种 Fol-PαCs（G3，DSF 2、4 和 7）中，Fol-PαC（G3，DSF 4）在 FR 阳性的 KB 细胞中具有最高的 siRNA 转移活性。Fol-PαC（G3，DSF 4）通过 FR 被内吞到 KB 细胞中。在 FR 阳性的 KB 细胞或 FR 阴性的 A549 细胞中，Fol-PαC（G3，DSF 4）与 siRNA 复合物直到电荷比为 100/1（载体/siRNA）时均未观察到细胞毒性。此外，Fol-PαC（G3，DSF 4）与 siRNA 复合物既没有引起干扰素反应，也没有引起炎症反应。重要的是，Fol-PαC（G3，DSF 4）与 siRNA 复合物在荷瘤小鼠肿瘤内注射和静脉注射后，倾向于显示体内 RNAi 效应。在小鼠静脉注射后，FITC 标记的 siRNA 和 TRITC 标记的 Fol-PαC（G3，DSF 4）实际上在肿瘤组织中积累。总之，本研究结果表明，Fol-PαC（G3，DSF 4）可能有潜力作为 FR 过表达癌细胞选择性 siRNA 递药载体在体外和体内使用。
