Diaz Miqueli Arlhee, Blanco Rances, Garcia Beatriz, Badia Teresita, Batista Ana E, Alonso Ruby, Montero Enrique
Center of Molecular Immunology, Havana, Cuba.
Hybridoma (Larchmt). 2007 Dec;26(6):423-31. doi: 10.1089/hyb.2007.0516.
Epidermal growth factor receptor (EGFR) is frequently overexpressed in epithelial tumors and is associated with a poor prognosis. An increasing interest in developing anti-EGFR therapies has resulted in the evaluation of monoclonal antibodies with the capacity to bind to the EGFR, inhibiting EGFR-dependent cellular transformation. A differential toxicity and therapeutic effect in vivo are associated with the affinity and isotype of the molecule. In this study, we examined the biological activities of three monoclonal antibodies (MAbs) -- Ior egf/r3 (mouse IgG2a, 10(-9) M), Nimotuzumab (humanized IgG1, 10(-9) M), and Cetuximab (human/mouse chimeric IgG1, 10(-10) M) -- considering inhibition of cell proliferation, apoptosis, and complement-mediated cell death in squamous cell carcinoma A431 in vitro. All the antibodies bound to the EGFR on these cells, inhibiting the receptor phosphorylation, as measured by flow cytometry, inmunocytochemistry, and Western blot. Exposure to the different antibodies inhibited cell proliferation in culture in a range from 50 to 80% compared to controls. Furthermore, similar capabilities to induce either complement-mediated cytotoxicity (ranging between 70 and 90%) or a two-fold increase in the rate of apoptotic cells were found when tumor cells were exposed to the antibodies. These results suggest that the affinity between specific anti-EGFR antibodies and its receptor could affect, but not determine their biological activity at least in those cell lines that exhibit high sensitivity to withheld EGFR. Our findings also confirm previous evidences that blocking EGFR in A431 cells by means of antibodies significantly changes tumor cell biology by promoting apoptosis while decreasing tumor cell proliferation.
表皮生长因子受体（EGFR）在上皮性肿瘤中常过度表达，且与预后不良相关。人们对开发抗EGFR疗法的兴趣日益浓厚，这促使人们对具有结合EGFR能力的单克隆抗体进行评估，以抑制EGFR依赖性细胞转化。分子的亲和力和同种型与体内不同的毒性和治疗效果相关。在本研究中，我们检测了三种单克隆抗体（MAbs）——Ior egf/r3（小鼠IgG2a，10⁻⁹ M）、尼妥珠单抗（人源化IgG1，10⁻⁹ M）和西妥昔单抗（人/鼠嵌合IgG1，10⁻¹⁰ M）——在体外对鳞状细胞癌A431细胞增殖、凋亡和补体介导的细胞死亡的抑制作用。通过流式细胞术、免疫细胞化学和蛋白质印迹法检测发现，所有抗体均与这些细胞上的EGFR结合，抑制受体磷酸化。与对照组相比，暴露于不同抗体后，培养中的细胞增殖受到50%至80%的抑制。此外，当肿瘤细胞暴露于这些抗体时，发现它们具有相似的诱导补体介导的细胞毒性（70%至90%）或使凋亡细胞率增加两倍的能力。这些结果表明，特异性抗EGFR抗体与其受体之间的亲和力可能会影响，但至少在那些对EGFR抑制表现出高敏感性细胞系中，不能决定它们的生物学活性。我们的研究结果还证实了先前的证据，即通过抗体阻断A431细胞中的EGFR可通过促进凋亡同时减少肿瘤细胞增殖，显著改变肿瘤细胞生物学特性。
