Blockade of epidermal growth factor receptor function by bivalent and monovalent fragments of 225 anti-epidermal growth factor receptor monoclonal antibodies.
Blockade of epidermal growth factor receptor function by bivalent and monovalent fragments of 225 anti-epidermal growth factor receptor monoclonal antibodies.
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发表时间：
1993-09
期刊：
影响因子：
11.2
通讯作者：
Zhen Fan;Hideo Masui;Ian Altas;John Mendelsohn
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文献类型：
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作者：
Zhen Fan;Hideo Masui;Ian Altas;John Mendelsohn
我们之前描述过抗表皮生长因子（EGF）受体单克隆抗体（MAb），它可以阻断转化生长因子α（TGF-α）和EGF与受体的结合并抑制受体酪氨酸激酶的激活。涉及细胞培养物和裸鼠异种移植物的这些 MAb 的研究证明了它们抑制多种肿瘤细胞系生长的能力，这些肿瘤细胞系表达 EGF 受体和 TGF-α，并且细胞增殖似乎依赖于受体激活。为了探索抗 EGF 受体 225 MAb 抑制细胞增殖的机制，我们将天然 225 MAb 的活性与对二价 225 F(ab')2 和单价 225 Fab' 片段的反应进行了比较。天然 225 MAb 及其片段均可抑制 125I-EGF 与 EGF 受体的结合。 Scatchard 分析表明，225 F(ab')2 的 Kd 与 225 MAb (1 nM) 相当，而 225 Fab' 的 Kd 为 5 nM。通过 MCF10A 非恶性人乳腺细胞、MDA468 人乳腺癌细胞和 A431 人上 EGF 受体酪氨酸残基的自磷酸化进行测定，二价 225 MAb 和 225 F(ab')2 以及单价 225 Fab' 均能够完全抑制 TGF-α 诱导的 EGF 受体酪氨酸激酶活化 外阴鳞状癌细胞。 MAb 的二价形式可以抑制这三种细胞系培养物中内源性（自分泌）TGF-α 刺激的增殖。他们还在 MCF10A 细胞培养物中添加外源 TGF-α 来阻断生长刺激，以及外源 TGF-α 对 MDA468 和 A431 细胞培养物的生长抑制作用。单价225 Fab'对这些细胞系的增殖具有较弱的抑制作用。为了确定抗 EGF 受体 MAb 的体内抗增殖活性是否可以在没有 MAb Fc 部分参与的情况下发生，225 F(ab')2 和天然 225 MAb 抑制皮下生长的能力。比较 A431 细胞异种移植物。以相当于分子半衰期的时间间隔施用等摩尔量的225 MAb或225 F(ab')2，以尝试维持可比较的血浆水平。 225 MAb 和 225 F(ab')2 均以剂量依赖性方式抑制 A431 细胞异种移植物生长，在完整抗体的情况下反应更持久。（摘要截断为 400 字）
We have previously described anti-epidermal growth factor (EGF) receptor monoclonal antibodies (MAbs) which can block binding of transforming growth factor alpha (TGF-alpha) and EGF to receptors and inhibit activation of receptor tyrosine kinase. Studies with these MAbs involving cell cultures and nude mouse xenografts demonstrated their capacity to inhibit the growth of a variety of tumor cell lines, which express EGF receptors and TGF-alpha and appear to depend upon receptor activation for cell proliferation. To explore the mechanism(s) by which anti-EGF receptor 225 MAb inhibits cell proliferation, we have compared the activity of native 225 MAb with the response to bivalent 225 F(ab')2 and monovalent 225 Fab' fragments. Both native 225 MAb and its fragments could inhibit the binding of 125I-EGF to EGF receptors. Scatchard analysis revealed that the Kd of 225 F(ab')2 is comparable to that of 225 MAb (1 nM), whereas the Kd of 225 Fab' is 5 nM. Both bivalent 225 MAb and 225 F(ab')2 and monovalent 225 Fab' were able to completely inhibit TGF-alpha-induced EGF receptor tyrosine kinase activation, as assayed by autophosphorylation of tyrosine residues of EGF receptors on MCF10A nonmalignant human mammary cells, MDA468 human breast adenocarcinoma cells, and A431 human vulvar squamous carcinoma cells. The bivalent forms of MAb could inhibit proliferation stimulated by endogenous (autocrine) TGF-alpha in cultures of these three cell lines. They also blocked growth stimulation by added exogenous TGF-alpha in cultures of MCF10A cells and the growth-inhibitory effect of exogenous TGF-alpha upon MDA468 and A431 cell cultures. Monovalent 225 Fab' had weaker inhibitory effects upon the proliferation of these cell lines. To determine whether the in vivo antiproliferative activity of anti-EGF receptor MAb can occur without the participation of the Fc portion of MAb, the capacities of 225 F(ab')2 and native 225 MAb to inhibit growth of s.c. A431 cell xenografts were compared. Equimolar amounts of either 225 MAb or 225 F(ab')2 were administered at intervals equivalent to the half-lives of the molecules, to attempt to maintain comparable plasma levels. Both 225 MAb and 225 F(ab')2 inhibited A431 cell xenograft growth in a dose-dependent manner, with a more sustained response in the case of the intact antibody.(ABSTRACT TRUNCATED AT 400 WORDS)