Fattah Omar M, Cloutier Sylvain M, Kündig Christoph, Felber Loyse M, Gygi Christian M, Jichlinski Patrice, Leisinger Hans-Jürg, Gauthier Eric R, Mach Jean Pierre, Deperthes David
Department of Urology, Urology Research Unit, CHUV, Epalinges, Switzerland.
Int J Cancer. 2006 Nov 15;119(10):2455-63. doi: 10.1002/ijc.21541.
The epidermal growth factor receptor (EGFR) plays a central role in cell life by controlling processes such as growth or proliferation. This receptor is commonly overexpressed in a number of epithelial malignancies and its upregulation is often associated with an aggressive phenotype of the tumor. Thus, targeting of EGFR represents a very promising challenge in oncology, and antibodies raised against this receptor have been investigated as potential antitumor agents. Various putative mechanisms of action were proposed for such antibodies, including decreased proliferation, induction of apoptosis, stimulation of the immunological response against targeted cancer cells or combinations thereof. We report here the development of an alternative high affinity molecule that is directed against EGFR. Production of this pentameric protein, named peptabody-EGF, includes expression in a bacterial expression system and subsequent refolding and multimerization of peptabody monomers. The protein complex contains 5 human EGF ligand domains, which confer specific binding towards the extracellular portion of EGFR. Receptor binding of the peptabody-EGF had a strong antiproliferative effect on different cancer cell lines overexpressing EGFR. However, cells expressing constitutive levels of the target receptor were barely affected. Peptabody-EGF treated cancer cells exhibited typical characteristics of apoptosis, which was found to be induced within 30 min after the addition of the peptabody-EGF. In vitro experiments demonstrated a significantly higher binding activity for peptabody-EGF than for the therapeutic monoclonal EGFR antibody Mab-425. Furthermore, the antitumor action provoked by the peptabody-EGF was greatly superior than antibody mediated effects when tested on EGFR overexpressing cancer cell lines. These findings suggest a potential application of this high affinity molecule as a novel tool for anti-EGFR therapy.
表皮生长因子受体（EGFR）通过控制生长或增殖等过程在细胞生命中发挥核心作用。该受体在多种上皮恶性肿瘤中通常过度表达，其上调往往与肿瘤的侵袭性表型相关。因此，靶向EGFR是肿瘤学中一个非常有前景的挑战，针对该受体产生的抗体已作为潜在的抗肿瘤药物进行了研究。针对此类抗体提出了各种假定的作用机制，包括增殖减少、凋亡诱导、针对靶向癌细胞的免疫反应刺激或其组合。我们在此报告一种针对EGFR的新型高亲和力分子的研发情况。这种名为peptabody-EGF的五聚体蛋白的生产包括在细菌表达系统中表达，随后对peptabody单体进行重折叠和多聚化。该蛋白复合物包含5个人表皮生长因子配体结构域，赋予其对EGFR细胞外部分的特异性结合能力。peptabody-EGF与受体的结合对不同过度表达EGFR的癌细胞系具有强烈的抗增殖作用。然而，表达目标受体组成水平的细胞几乎未受影响。经peptabody-EGF处理的癌细胞表现出典型的凋亡特征，发现添加peptabody-EGF后30分钟内即诱导凋亡。体外实验表明，peptabody-EGF的结合活性明显高于治疗性单克隆EGFR抗体Mab-425。此外，在过度表达EGFR的癌细胞系上进行测试时，peptabody-EGF引发的抗肿瘤作用比抗体介导的作用要强得多。这些发现表明这种高亲和力分子作为抗EGFR治疗新工具的潜在应用价值。
