Taetle R, Honeysett J M, Houston L L
Department of Medicine, University of California, San Diego.
J Natl Cancer Inst. 1988 Sep 7;80(13):1053-9. doi: 10.1093/jnci/80.13.1053.
The effects of antiepidermal growth factor (EGF) receptor monoclonal antibodies (MAbs) 528 and 225 and a 528-ricin A conjugate on the growth of normal and malignant human cells were tested in vitro. Malignant human cell lines with EGF receptor numbers ranging from 0 to 4 X 10(5) receptors/cell, human fetal fibroblasts, and normal marrow granulocyte/macrophage progenitors (CFU-gm) showed no effect when grown with 10(-12) M to 10(-7) M MAb 225 or 528. MAbs 225 and 528 and EGF also had no effect on the ability of marrow stromal cells to maintain CFU-gm viability in long-term marrow cultures. Reversible growth inhibition of A431 epidermoid and MDA-468 breast carcinoma cells with 2 and 3 X 10(6) EGF receptors/cell, respectively, was observed with both antibodies and with 10(-8) M EGF. In contrast, an immunoconjugate prepared with MAb 528 and recombinant ricin A chain (528-rRA) showed dose-dependent killing over a concentration range of 10(-12) M to 10(-8) M against cells with greater than or equal to 1.2 X 10(5) EGF receptors/cell [concentration that causes 50% inhibition of growth (IC50) values, approximately 10(-12) M to 10(-10) M]. Human fetal fibroblasts (5.6 X 10(4) EGF receptors/cell), melanoma cells without detectable EGF receptors, and human CFU-gm showed IC50 values of greater than 10(-8) M. Killing of KB epidermoid carcinoma cells and 547 ovarian carcinoma cells with 4 and 1.2 X 10(5) EGF receptors/cell by 10(-10) or 10(-11) M 528-rRA was time dependent, but cytotoxicity to 547 cells was not complete even with 48 hours of immunotoxin treatment. Cytotoxicity of 528-rRA was not enhanced by chloroquine or verapamil. In vitro, anti-EGF receptor MAbs cause reversible antiproliferative effects only against malignant cell lines with amplified EGF receptor expression. In contrast, 528-rRA shows potent, specific toxicity to cells with greater than 50,000 EGF receptors/cell. However, kinetics of cell killing with 528-rRA are protracted, suggesting that prolonged exposure may be required for in vivo antitumor effects.
在体外测试了抗表皮生长因子（EGF）受体单克隆抗体（MAb）528和225以及528-蓖麻毒蛋白A缀合物对正常和恶性人类细胞生长的影响。表皮生长因子受体数量范围为0至4×10⁵个受体/细胞的恶性人类细胞系、人胎儿成纤维细胞以及正常骨髓粒细胞/巨噬细胞祖细胞（CFU-gm），在与10⁻¹²M至10⁻⁷M的MAb 225或528一起培养时未显示出影响。MAb 225和528以及EGF对骨髓基质细胞在长期骨髓培养中维持CFU-gm活力的能力也没有影响。用这两种抗体以及10⁻⁸M EGF分别观察到对A431表皮样癌细胞和MDA-468乳腺癌细胞（分别具有2×10⁶和3×10⁶个EGF受体/细胞）的可逆生长抑制。相比之下，用MAb 528和重组蓖麻毒蛋白A链制备的免疫缀合物（528-rRA）在10⁻¹²M至10⁻⁸M的浓度范围内对具有大于或等于1.2×10⁵个EGF受体/细胞的细胞表现出剂量依赖性杀伤作用[导致生长抑制50%的浓度（IC50）值，约为10⁻¹²M至10⁻¹⁰M]。人胎儿成纤维细胞（5.6×10⁴个EGF受体/细胞）、未检测到EGF受体的黑色素瘤细胞以及人CFU-gm的IC50值大于10⁻⁸M。10⁻¹⁰或10⁻¹¹M的528-rRA对具有4×10⁵和1.2×10⁵个EGF受体/细胞的KB表皮样癌细胞和547卵巢癌细胞的杀伤作用是时间依赖性的，但即使进行48小时的免疫毒素处理，对547细胞的细胞毒性也不完全。氯喹或维拉帕米未增强528-rRA的细胞毒性。在体外，抗EGF受体单克隆抗体仅对具有扩增的EGF受体表达的恶性细胞系产生可逆的抗增殖作用。相比之下，528-rRA对具有大于50,000个EGF受体/细胞的细胞显示出强大的特异性毒性。然而，528-rRA的细胞杀伤动力学较为缓慢，这表明体内抗肿瘤作用可能需要延长暴露时间。
