Kusano-Arai Osamu, Iwanari Hiroko, Kudo Shota, Kikuchi Chika, Yui Anna, Akiba Hiroki, Matsusaka Keisuke, Kaneda Atsushi, Fukayama Masashi, Tsumoto Kouhei, Hamakubo Takao
1 Department of Quantitative Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo , Tokyo, Japan .
2 Institute of Immunology Co. Ltd. , Tokyo, Japan .
Monoclon Antib Immunodiagn Immunother. 2018 Feb;37(1):1-11. doi: 10.1089/mab.2017.0043.
Cadherin-17 (CDH17) is highly expressed in gastric cancer and is thus considered to be a good target for antibody therapy. CDH17 is classified as a nonclassical cadherin, in that it is composed of seven extracellular cadherin domains. We generated anti-CDH17 monoclonal antibodies (mAbs) which recognize the extracellular domain of CDH17. Competitive assay using AGS, a gastric cancer cell line, cells revealed that five selected anti-CDH17 mAbs recognize different epitopes on CDH17. As AGS cells were shown to exhibit broad expression pattern of CDH17 by flow cytometry, we separated three clones with a low (10,000/cell), medium (50,000/cell), and high (200,000/cell) expression level, designating them as AGS, AGS, and AGS, respectively. The mAbs, coupled with saporin, exhibited effective cytotoxicity to AGS, but poor cytotoxicity to AGS. By contrast, the immunotoxin cocktail using the three clones D2101, D2005, and D2008, which recognize different epitopes, exhibited efficient cytotoxicity, even to the AGS group. The effect of the immunotoxin cocktail is synergistic, as the combination index was demonstrated to be below 1.0, as calculated by the method of Chou and Talalay using CalcuSyn software. These results suggest that the immunotoxin cocktail targeted to multiple epitopes has synergistic effects on low expression level cells, which expand the applicable range of immunotoxin therapy for cancer.
钙黏蛋白-17（CDH17）在胃癌中高表达，因此被认为是抗体治疗的良好靶点。CDH17被归类为非经典钙黏蛋白，因为它由七个细胞外钙黏蛋白结构域组成。我们制备了识别CDH17细胞外结构域的抗CDH17单克隆抗体（mAb）。使用胃癌细胞系AGS进行的竞争性试验表明，五种选定的抗CDH17 mAb识别CDH17上不同的表位。由于流式细胞术显示AGS细胞呈现广泛的CDH17表达模式，我们分离出三个表达水平低（10,000/细胞）、中（50,000/细胞）和高（200,000/细胞）的克隆，分别将它们命名为AGS、AGS和AGS。与皂草毒素偶联的mAb对AGS表现出有效的细胞毒性，但对AGS的细胞毒性较差。相比之下，使用识别不同表位的三个克隆D2101、D2005和D2008的免疫毒素混合物，即使对AGS组也表现出高效的细胞毒性。免疫毒素混合物的作用是协同的，因为根据Chou和Talalay的方法使用CalcuSyn软件计算得出的组合指数证明低于1.0。这些结果表明，靶向多个表位的免疫毒素混合物对低表达水平细胞具有协同作用，这扩大了免疫毒素疗法在癌症治疗中的适用范围。
