Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York, USA.
Mol Ther Nucleic Acids. 2012 May 15;1(5):e21. doi: 10.1038/mtna.2012.14.
The transferrin receptor, CD71, is an attractive target for drug development because of its high expression on a number of cancer cell lines and the blood brain barrier. To generate serum-stabilized aptamers that recognize the human transferrin receptor, we have modified the traditional aptamer selection protocol by employing a functional selection step that enriches for RNA molecules which bind the target receptor and are internalized by cells. Selected aptamers were specific for the human receptor, rapidly endocytosed by cells and shared a common core structure. A minimized variant was found to compete with the natural ligand, transferrin, for receptor binding and cell uptake, but performed ~twofold better than it in competition experiments. Using this molecule, we generated aptamer-targeted siRNA-laden liposomes. Aptamer targeting enhanced both uptake and target gene knockdown in cells grown in culture when compared to nonmodified or nontargeted liposomes. The aptamer should prove useful as a surrogate for transferrin in many applications including cell imaging and targeted drug delivery.
转铁蛋白受体 CD71 由于在许多癌细胞系和血脑屏障上的高表达，成为药物开发的一个有吸引力的靶点。为了生成能够识别人类转铁蛋白受体的血清稳定适体，我们通过采用功能选择步骤修改了传统的适体选择方案，该步骤富集与靶受体结合并被细胞内化的 RNA 分子。所选适体特异性识别人受体，被细胞快速内吞，并具有共同的核心结构。发现一个最小化的变体与天然配体转铁蛋白竞争受体结合和细胞摄取，但在竞争实验中表现优于它约两倍。使用这种分子，我们生成了适体靶向载有 siRNA 的脂质体。与未修饰或非靶向脂质体相比，适体靶向在细胞培养中显著提高了摄取和靶基因敲低。该适体在包括细胞成像和靶向药物递送在内的许多应用中有望成为转铁蛋白的替代品。
