Diphtheria toxin mutant CRM197 possesses weak EF2-ADP-ribosyl activity that potentiates its anti-tumorigenic activity.
Diphtheria toxin mutant CRM197 possesses weak EF2-ADP-ribosyl activity that potentiates its anti-tumorigenic activity.
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DOI：
10.1093/jb/mvm116
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发表时间：
2007-07
影响因子：
2.7
通讯作者：
T. Kageyama;Minako Ohishi;S. Miyamoto;H. Mizushima;R. Iwamoto;E. Mekada
中科院分区：
文献类型：
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作者：
T. Kageyama;Minako Ohishi;S. Miyamoto;H. Mizushima;R. Iwamoto;E. Mekada
CRM197是一种突变的白喉毒素(DT)，长期以来被认为是一种无毒蛋白。基于其无毒的特性，该蛋白已被用于各种目的，包括作为肝素结合的EGF样生长因子(HB-EGF)的抑制剂和作为疫苗接种的免疫佐剂。在这里，我们展示了CRM197具有弱毒性的证据。在高表达DT受体/proHB-EGF的细胞中观察到这种毒性，但在亲本细胞中没有观察到这种毒性，表明这种毒性是通过DT受体介导的。CRM197对具有延伸因子2突变的DT耐药细胞没有任何毒性，无细胞实验显示CRM197片段A中存在弱的EF-2-ADP核糖化活性。因此，本研究表明，尽管CRM197的毒性比野生型DT低约10(6)倍，但在高剂量使用CRM197时需要特殊护理。我们发现，抗DT的单抗可抑制CRM197的毒性，但不影响CRM197对HB-EGF诱导的有丝分裂活性的抑制活性。CRM197对裸鼠体内肿瘤生长有强烈抑制作用。抗DT单抗与CRM197共同作用后，CRM197的抗肿瘤作用减弱，表明CRM197的毒性增强了其抗肿瘤作用。
CRM197, a mutated diphtheria toxin (DT), has long been recognized to be a non-toxic protein. Based on its non-toxic feature, this protein has been utilized for various purposes, including as an inhibitor of heparin-binding EGF-like growth factor (HB-EGF) and as an immunological adjuvant for vaccination. Here we show evidence that CRM197 has a weak toxicity. This toxicity was observed in cells over-expressing the DT receptor/proHB-EGF, but not in parental cells, indicating that the toxicity was mediated through DT receptor. CRM197 did not show any toxicity toward DT-resistant cells, which have a mutation in elongation factor 2, and a cell-free assay revealed the existence of weak EF-2-ADP ribosylation activity in fragment A of CRM197. Thus, the present study indicates a requirement for specific care in the use of CRM197 at a high dosage, although the toxicity of CRM197 is about 10(6) times less than that of wild-type DT. We found that a monoclonal antibody to DT inhibited CRM197 toxicity, but did not affect the inhibitory activity of CRM197 toward HB-EGF-induced mitogenic activity. CRM197 strongly inhibits tumour growth in nude mice. The anti-DT monoclonal antibody administered with CRM197 reduced the anti- tumourigenic effect of CRM197, indicating that the toxicity of CRM197 potentiates its anti- tumourigenic effect.