Institute for Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Albertstr. 25, 79104 Freiburg, Germany.
Institute of Surgical Pathology, Medical Center - University of Freiburg, Breisacherstr. 115a, 79106 Freiburg, Germany.
Sci Rep. 2017 Jan 27;7:41252. doi: 10.1038/srep41252.
The actin cytoskeleton is an attractive target for bacterial toxins. The ADP-ribosyltransferase TccC3 from the insect bacterial pathogen Photorhabdus luminescence modifies actin to force its aggregation. We intended to transport the catalytic part of this toxin preferentially into cancer cells using a toxin transporter (Protective antigen, PA) which was redirected to Epidermal Growth Factor Receptors (EGFR) or to human EGF receptors 2 (HER2), which are overexpressed in several cancer cells. Protective antigen of anthrax toxin forms a pore through which the two catalytic parts (lethal factor and edema factor) or other proteins can be transported into mammalian cells. Here, we used PA as a double mutant (N682A, D683A; mPA) which cannot bind to the two natural anthrax receptors. Each mutated monomer is fused either to EGF or to an affibody directed against the human EGF receptor 2 (HER2). We established a cellular model system composed of two cell lines representing HER2 overexpressing esophageal adenocarcinomas (EACs) and EGFR overexpressing esophageal squamous cell carcinomas (ESCCs). We studied the specificity and efficiency of the re-directed anthrax pore for transport of TccC3 toxin and established Photorhabdus luminescence TccC3 as a toxin suitable for the development of a targeted toxin selectively killing cancer cells.
肌动蛋白细胞骨架是细菌毒素的一个有吸引力的靶点。来自昆虫细菌病原体发光杆菌的 ADP-核糖基转移酶 TccC3 修饰肌动蛋白以迫使其聚集。我们打算使用毒素转运蛋白（保护性抗原，PA）将这种毒素的催化部分优先输送到癌细胞中，该转运蛋白被重定向到表皮生长因子受体（EGFR）或人表皮生长因子受体 2（HER2），这些受体在多种癌细胞中过度表达。炭疽毒素的保护性抗原形成一个孔，通过该孔可以将两种催化部分（致死因子和水肿因子）或其他蛋白质输送到哺乳动物细胞中。在这里，我们使用 PA 作为不能与两种天然炭疽受体结合的双突变体（N682A，D683A；mPA）。每个突变单体与 EGF 或针对人表皮生长因子受体 2（HER2）的亲和体融合。我们建立了一个由两种代表过表达 HER2 的食管腺癌（EAC）和过表达 EGFR 的食管鳞状细胞癌（ESCC）的细胞系组成的细胞模型系统。我们研究了重新定向的炭疽孔用于转运 TccC3 毒素的特异性和效率，并确立了发光杆菌 TccC3 作为一种适合开发选择性杀伤癌细胞的靶向毒素的毒素。
