Pickering J G, Bacha P A, Weir L, Jekanowski J, Nichols J C, Isner J M
Department of Medicine, St. Elizabeth's Hospital, Tufts University School of Medicine, Boston, Massachusetts 02135.
J Clin Invest. 1993 Feb;91(2):724-9. doi: 10.1172/JCI116254.
Smooth muscle cell proliferation in the intima of arteries is a principal event associated with vascular narrowing after balloon angioplasty and bypass surgery. Techniques for limiting smooth muscle cell proliferation, however, have not as yet yielded any therapeutic benefit for these conditions. This may reflect the present lack of sufficiently potent and specific inhibitors of smooth muscle cell proliferation. DAB389 EGF is a genetically engineered fusion protein in which the receptor-binding domain of diphtheria toxin has been replaced by human epidermal growth factor. We evaluated the effect of this fusion toxin on human vascular smooth muscle cells in culture. Incubation of proliferating cells with DAB389 EGF yielded a dose-dependent inhibition of protein synthesis, as assessed by uptake of [3H]leucine, with an IC50 of 40 pM. The cytotoxic effect was inhibited in the presence of excess EGF or with monoclonal antibody to the EGF receptor. We further studied the effect of the fusion toxin on smooth muscle cell outgrowth from human atherosclerotic plaque. Outgrowth was markedly inhibited after as little as 1 h of exposure to the fusion protein. Furthermore, complete inhibition of proliferation of cells within the plaque could be attained. These results demonstrate that DAB389 EGF is highly cytotoxic to human smooth muscle cells proliferating in culture and can prevent smooth muscle cell outgrowth from "growth-stimulated" human atherosclerotic plaque. DAB389 EGF may therefore be of therapeutic value in vascular diseases characterized by smooth muscle cell accumulation.
动脉内膜平滑肌细胞增殖是与球囊血管成形术和搭桥手术后血管狭窄相关的主要事件。然而，限制平滑肌细胞增殖的技术尚未对这些病症产生任何治疗益处。这可能反映了目前缺乏足够强效和特异性的平滑肌细胞增殖抑制剂。DAB389 EGF是一种基因工程融合蛋白，其中白喉毒素的受体结合结构域已被人表皮生长因子取代。我们评估了这种融合毒素对培养的人血管平滑肌细胞的作用。用DAB389 EGF孵育增殖细胞，通过[3H]亮氨酸摄取评估，产生了剂量依赖性的蛋白质合成抑制，IC50为40 pM。在过量EGF存在下或用抗EGF受体单克隆抗体时，细胞毒性作用受到抑制。我们进一步研究了融合毒素对人动脉粥样硬化斑块中平滑肌细胞生长的影响。暴露于融合蛋白仅1小时后，生长就受到明显抑制。此外，可以完全抑制斑块内细胞的增殖。这些结果表明，DAB389 EGF对培养中增殖的人平滑肌细胞具有高度细胞毒性，并可防止平滑肌细胞从“生长刺激的”人动脉粥样硬化斑块中生长出来。因此，DAB389 EGF在以平滑肌细胞积聚为特征的血管疾病中可能具有治疗价值。
