Antibody targeting of the EphA2 tyrosine kinase inhibits malignant cell behavior.
Antibody targeting of the EphA2 tyrosine kinase inhibits malignant cell behavior.
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发表时间：
2002-05
期刊：
影响因子：
11.2
通讯作者：
Kelly Carles‐Kinch;K. Kilpatrick;J. Stewart;M. Kinch
中科院分区：
文献类型：
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作者：
Kelly Carles‐Kinch;K. Kilpatrick;J. Stewart;M. Kinch
EphA 2是一种跨膜受体酪氨酸激酶，在许多侵袭性癌细胞中上调。尽管EphA 2过表达，但恶性细胞上的EphA 2不能结合其配体ephrinA 1，ephrinA 1锚定在相邻细胞的膜上。与其他受体激酶不同，EphA 2表现出不依赖于配体结合的激酶活性。然而，配体结合导致EphA 2负调节肿瘤细胞生长和迁移。在此，我们将EphA 2的知识转化为选择性靶向恶性细胞的策略。使用一种新的方法来保护细胞外表位并优化抗体多样性，我们产生了识别EphA 2细胞外结构域表位的单克隆抗体。选择EphA 2抗体是因为它们能够抑制转移性细胞特有的行为，同时使对非转化细胞的损伤最小化。发现EphA 2单克隆抗体的子集抑制MDA-MB-231乳腺肿瘤细胞的软琼脂定殖，但不影响非转化的MCF-10A乳腺上皮细胞的单层生长。这些EphA 2抗体还阻止肿瘤细胞在重建的基底膜上形成管状网络，这是转移特性的敏感指标。生化分析表明，生物活性抗体诱导EphA 2磷酸化和随后的降解。基于反义的EphA 2靶向类似地抑制软琼脂定殖，表明抗体通过下调EphA 2来抑制恶性行为。这些结果表明了基于抗体靶向过表达EphA 2的许多癌症的机会。我们的研究还强调了如何利用肿瘤特异性细胞行为来识别和筛选潜在的治疗靶点。
EphA2 is a transmembrane receptor tyrosine kinase that is up-regulated on many aggressive carcinoma cells. Despite its overexpression, the EphA2 on malignant cells fails to bind its ligand, ephrinA1, which is anchored to the membrane of adjacent cells. Unlike other receptor kinases, EphA2 demonstrates kinase activity that is independent of ligand binding. However, ligand binding causes EphA2 to negatively regulate tumor cell growth and migration. Herein, we translate knowledge of EphA2 into strategies that selectively target malignant cells. Using a novel approach to preserve extracellular epitopes and optimize antibody diversity, we generated monoclonal antibodies that identify epitopes on the extracellular domain of EphA2. EphA2 antibodies were selected for their abilities to inhibit behaviors that are unique to metastatic cells while minimizing damage to nontransformed cells. A subset of EphA2 monoclonal antibodies were found to inhibit the soft agar colonization by MDA-MB-231 breast tumor cells but did not affect monolayer growth by nontransformed MCF-10A breast epithelial cells. These EphA2 antibodies also prevented tumor cells from forming tubular networks on reconstituted basement membranes, which is a sensitive indicator of metastatic character. Biochemical analyses showed that biologically active antibodies induced EphA2 phosphorylation and subsequent degradation. Antisense-based targeting of EphA2 similarly inhibited soft agar colonization, suggesting that the antibodies repress malignant behavior by down-regulating EphA2. These results suggest an opportunity for antibody-based targeting of the many cancers that overexpress EphA2. Our studies also emphasize how tumor-specific cellular behaviors can be exploited to identify and screen potential therapeutic targets.