Proshkina G M, Kiseleva D V, Shilova O N, Ryabova A V, Shramova E I, Stremovskiy O A, Deyev S M
Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997 Russia.
Department of BiologyMoscow State University, Moscow, 119234 Russia.
Mol Biol (Mosk). 2017 Nov-Dec;51(6):997-1007. doi: 10.7868/S0026898417060118.
We have generated and characterized HER2-specific targeted toxin based on the low-immunogenic variant of Pseudomonas exotoxin A (LoPE), in which most of the human immunodominant B-cell epitopes have been inactivated. Nonimmunoglobulin DARPin-based HER2-specific protein was used as a targeting module for toxin delivery to the cellular target. Using confocal microscopy, it has been found that both domains in this hybrid toxin retained their functionality, i.e., the specific interaction with HER2 receptor, as well as the internalization and effective transport to ER typical of the wild-type Pseudomonas exotoxin A. The HER2-dependent cytotoxic effect correlated with receptor expression level at the cell surface, as shown in vitro using cell lines with different levels of HER2 expression. Due to the very high selective cytotoxicity against HER2-positive human tumor cells, as well as expected low immunogenicity, we believe that this new targeted toxin may be promising for future in vivo studies as a therapeutic agent for HER2-positive tumors.
我们基于绿脓杆菌外毒素A的低免疫原性变体（LoPE）生成并表征了HER2特异性靶向毒素，其中大部分人免疫显性B细胞表位已失活。基于非免疫球蛋白的DARPin的HER2特异性蛋白用作将毒素递送至细胞靶点的靶向模块。使用共聚焦显微镜发现，这种杂合毒素的两个结构域都保留了其功能，即与HER2受体的特异性相互作用，以及野生型绿脓杆菌外毒素A典型的内化和向内质网的有效转运。HER2依赖性细胞毒性作用与细胞表面受体表达水平相关，如使用具有不同HER2表达水平的细胞系在体外所示。由于对HER2阳性人肿瘤细胞具有非常高的选择性细胞毒性，以及预期的低免疫原性，我们认为这种新型靶向毒素作为HER2阳性肿瘤的治疗剂，在未来的体内研究中可能具有前景。
