白喉毒素 (diphtheria toxin DT) 是棒状白喉杆菌被β噬菌体感染后分泌的一种外毒素. 它可以阻断真核细胞的蛋白质合成,杀死细胞. 血管内皮生长因子 (VEGF) 的 R82A, K84A, H86A 突变体可以和肿瘤血管上高表达的 VEGF 受体 1 (VEGFR-1) 特异性结合. 首先从白喉杆菌中提取基因组 DNA,扩增出白喉毒素 C 区、 T 区基因. 并运用点突变技术,制成 VEGF 的 R82A, K84A, H86A 突变体. 利用这个可以和肿瘤血管上特异性受体相结合的 VEGF 的突变体,代替白喉毒素上的受体结合区,制成了针对 VEGFR-1 的靶向融合毒素——— DT391-mVEGF. 以去除了受体结合区的 DT391 为阴性对照,细胞实验表明,融合毒素对 VEGFR-1 阳性的肿瘤细胞有特异性杀伤作用.
Diphtheria toxin is an exotoxin secreted by Corynebacterium diphtheriae that has been lysogenized by β bacteriophage that carries the DT gene. It blocks protein synthesis and kills the target eukaryotic cell. The R82A , K84A , H86A mutant of vascular endothelial growth factor (VEGF) specially binds its receptor 1 (VEGFR-1) that is expressed highly on surface of tumor blood vessel. DT genomic DNA was extracted first and then the gene that coding the T domain and C domain of DT (DT391) were amplified. The R82A , K84A , H86A mutant were introduced to VEGF by site-directed mutagenesis. Then a VEGFR-1 targeting fusion protein, DT391-mVEGF, was constructed by substituting the receptor binding domain of DT with the VEGF mutant which shows high affinity to a receptor expressed on tumor vascular. With DT391, a protein without the mVEGF domain of DT391-mVEGF, as a negative control in cytotoxicity assay, the hybrid protein DT391-mVEGF showed an inhibition to the growth of VEGFR-1 positive tumor cell.
白向阳,倪剑锋,吕安国,吴文芳,牛瑞芳.杀伤血管内皮生长因子受体 1 阳性细胞的靶向毒素[J].生物化学与生物物理进展,2005,32(4):365-370
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