Cytotoxicity and specificity of directed toxins composed of diphtheria toxin and the EGF-like domain of heregulin beta1.
Cytotoxicity and specificity of directed toxins composed of diphtheria toxin and the EGF-like domain of heregulin beta1.
复制标题
由白喉毒素和heregulin beta1的EGF样结构域组成的定向毒素的细胞毒性和特异性。
DOI：
10.1021/bi972326z
复制
发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Eisenberg,D
中科院分区：
文献类型：
--
作者：
Landgraf,R;Pegram,M;Slamon,DJ;Eisenberg,D
作为定向毒素设计的一个步骤，针对过表达HER受体的细胞，特别是乳腺癌细胞，我们研究了白喉毒素（DT）和heregulin β1嵌合体的特性。EGF样生长激素调蛋白是HER 3和HER 4受体及其与HER 2的异源二聚体的配体。heregulin的60个残基的EGF样结构域（hrg）主要通过其N末端与这些受体结合，从而引起生物学反应。我们测试了一种融合蛋白，其中hrg取代DT（DT（389）hrg）的C末端受体结合结构域，以及另一种设计，其中该结构域融合到DT（389）的N末端。在这两种构建体中，N-末端融合物作为定向毒素没有活性，但引起生长应答。hrg与DT（389）的C-末端融合产生功能性毒素，并显示与调蛋白特异性一致的细胞系特异性细胞毒性。受体活化、直接结合和与游离hrg竞争显示hrg与其同源受体的结合不受损害。细胞毒性依赖于DT（389）hrg与HER 3和HER 4受体的高亲和力结合，而不是由HER 2过表达单独介导。对于表现出高亲和力结合位点的那些细胞系，细胞毒性水平与内化速率相关。因此，DT（389）hrg嵌合体提供了一种可能的途径，定向毒素对细胞过度表达HER受体。
As a step in the design of directed toxins, aimed at cells that overexpress HER receptors, particularly breast carcinoma cells, we studied the properties of a chimera of diphtheria toxin (DT) and heregulin β1. The EGF-like growth hormone heregulin is a ligand for the HER3 and HER4 receptors and their heterodimers with HER2. The 60-residue EGF-like domain (hrg) of heregulin elicits a biological response and binds to these receptors primarily through its N terminus. We tested a fusion protein in which hrg replaces the C-terminal receptor-binding domain of DT (DT(389)hrg) and an alternative design in which this domain is fused to the N terminus of DT(389). Of those two constructs, the N-terminal fusion was not active as a directed toxin but elicited a growth response. The C-terminal fusion of hrg to DT(389) yielded a functional toxin and showed cell line specific cytotoxicity that is consistent with heregulin specificity. The binding of hrg to its cognate receptor is not impaired as shown by receptor activation, direct binding, and competition with free hrg. Cytotoxicity is dependent on high-affinity binding of DT(389)hrg to HER3 and HER4 receptors and is not mediated by HER2 overexpression alone. For those cell lines exhibiting high-affinity binding sites, the level of cytotoxicity correlates with the rate of internalization. Thus DT(389)hrg chimeras offer a possible avenue toward directed toxins against cells that overexpress HER receptors.