Apto-Pharm Ltd., Moscow, Russian Federation.
Chemistry Department, Lomonosov Moscow State University, Moscow, Russian Federation.
Nucleic Acid Ther. 2020 Jun;30(3):175-187. doi: 10.1089/nat.2019.0830. Epub 2020 Jan 28.
Nucleic acid aptamers have been proven to be a useful tool in many applications. Particularly, aptamers to epidermal growth factor receptor (EGFR) have been successfully used for the recognition of EGFR-expressing cells, the inhibition of EGFR-dependent pathways, and targeted drug delivery into EGFR-positive cells. Several aptamers are able to discriminate wild-type EGFR from its mutant form, EGFRvIII. Aptamers to EGFR have hairpin-like secondary structures with several possible folding variations. Here, an aptamer, previously selected to EGFRvIII, was chosen as a lead compound for extensive post-SELEX maturation. The aptamer was 1.5-fold truncated, the ends of the hairpin stem were appended with GC-pairs to increase thermal stability, and single pyrene modification was introduced into the aptamer to increase affinity to the target protein. Pyrene modification was selected from extensive computer docking studies of a library of thousands of chemicals to EGFR near the EGF-binding interface. The resulting aptamers bound extracellular domains of both variants of EGFR: EGFRwt and EGFRvIII with subnanomolar apparent dissociation constants. Compared with the initial aptamer, affinity to EGFRwt was increased up to 7.5-fold, whereas affinity to EGFRvIII was increased up to 4-fold.
核酸适体已被证明在许多应用中是一种有用的工具。特别是表皮生长因子受体（EGFR）的适体已成功用于识别表达 EGFR 的细胞、抑制 EGFR 依赖性途径以及将靶向药物递送到 EGFR 阳性细胞中。有几种适体能区分野生型 EGFR 和其突变形式 EGFRvIII。EGFR 的适体具有发夹状的二级结构，具有几种可能的折叠变化。在这里，选择了先前针对 EGFRvIII 选择的适体作为广泛的 SELEX 后成熟的先导化合物。适体被截断了 1.5 倍，发夹茎的末端被添加 GC 对以增加热稳定性，并将单个芘基修饰引入适体以增加与靶蛋白的亲和力。芘基修饰是从针对 EGFR 近 EGF 结合界面的数千种化学物质库的广泛计算机对接研究中选择的。所得的适体与 EGFRwt 和 EGFRvIII 的两种变体的细胞外结构域结合，其表观解离常数达到亚纳摩尔。与初始适体相比，对 EGFRwt 的亲和力增加了高达 7.5 倍，而对 EGFRvIII 的亲和力增加了高达 4 倍。
