Jing Chen, Yuan Lin, Xingguo Pan, Zhijie Huang, Zai-xi Chen, Ru Zhang, Jian You
Department of Cadre ward, The General Hospital of Chengdu Military Area, Chengdu, China.
Asian Pac J Cancer Prev. 2011;12(4):935-7.
Gliomas, with a poor clinical course, account for 30% to 40% of all intracranial tumors. Immunotherapy with monoclonal antibodies has emerged as a promising area of investigation and recently it has been shown that antibodies utilize complementarity-determining regions (CDRs) of their variable domains to bind to antigens with high affinity and specificity. Here, we designed an antibody mimetic fused with diphtheria toxin to target the U87 MG glioma cell line. VHCDR1 and VLCDR3, together with 5 amino acid residues on both side of the CDRs, through a cognate framework region (VHFR2) yielded a mimetic of BT32/A6 (United States Patent number: 5639863). We fused the mimetic with the first 388 amino acid residues of diphtheria toxin and E. coli strain BL21 (ED3) was used to express the soluble immunotoxin DT-MG. The immunotoxin DT-MG alone did not kill Raji up to the maximal concentration tested (10-6M) in vitro. By contrast, concentrations ≥ 10-9M, of the fused DT-MG killed more than 95% of U-87 MG cells. It is suggested that the mimetic maintained the synergic interactions and high-affinity associated with the parent antibody. This construct holds promise for targeting specific cancer epitopes and may be useful when incorporated into diagnostic and therapeutic regimens.
胶质瘤临床病程不佳，占所有颅内肿瘤的30%至40%。单克隆抗体免疫疗法已成为一个有前景的研究领域，最近有研究表明，抗体利用其可变区的互补决定区（CDR）以高亲和力和特异性结合抗原。在此，我们设计了一种与白喉毒素融合的抗体模拟物，以靶向U87 MG胶质瘤细胞系。VHCDR1和VLCDR3与CDR两侧的5个氨基酸残基一起，通过一个同源框架区（VHFR2）产生了BT32/A6的模拟物（美国专利号：5639863）。我们将该模拟物与白喉毒素的前388个氨基酸残基融合，并使用大肠杆菌菌株BL21（ED3）来表达可溶性免疫毒素DT-MG。在体外，单独的免疫毒素DT-MG在测试的最大浓度（10-6M）下都不能杀死Raji细胞。相比之下，浓度≥10-9M的融合DT-MG能杀死超过95%的U-87 MG细胞。这表明该模拟物保持了与亲本抗体相关的协同相互作用和高亲和力。这种构建体有望靶向特定的癌症表位，并且当纳入诊断和治疗方案时可能会有用。
