Graduate Group in Biophysics, University of California, San Francisco, California 94158-2517.
Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94158-2517.
J Biol Chem. 2010 Aug 27;285(35):26878-26888. doi: 10.1074/jbc.M109.077677. Epub 2010 May 25.
Interactions between urokinase plasminogen activator receptor (uPAR) and its various ligands regulate tumor growth, invasion, and metastasis. Antibodies that bind specific uPAR epitopes may disrupt these interactions, thereby inhibiting these processes. Using a highly diverse and naïve human fragment of the antigen binding (Fab) phage display library, we identified 12 unique human Fabs that bind uPAR. Two of these antibodies compete against urokinase plasminogen activator (uPA) for uPAR binding, whereas a third competes with beta1 integrins for uPAR binding. These competitive antibodies inhibit uPAR-dependent cell signaling and invasion in the non-small cell lung cancer cell line, H1299. Additionally, the integrin-blocking antibody abrogates uPAR/beta1 integrin-mediated H1299 cell adhesion to fibronectin and vitronectin. This antibody and one of the uPAR/uPA antagonist antibodies shows a significant combined effect in inhibiting cell invasion through Matrigel/Collagen I or Collagen I matrices. Our results indicate that these antagonistic antibodies have potential for the detection and treatment of uPAR-expressing tumors.
尿激酶型纤溶酶原激活物受体 (uPAR) 与其各种配体之间的相互作用调节肿瘤的生长、侵袭和转移。与特定 uPAR 表位结合的抗体可能会破坏这些相互作用，从而抑制这些过程。我们使用高度多样化和原始的人类抗原结合 (Fab) 噬菌体展示文库的片段，鉴定出 12 种独特的与人 uPAR 结合的 Fab。其中两种抗体与尿激酶纤溶酶原激活物 (uPA) 竞争 uPAR 结合，而第三种抗体与β1 整合素竞争 uPAR 结合。这些竞争性抗体抑制非小细胞肺癌细胞系 H1299 中依赖 uPAR 的细胞信号转导和侵袭。此外，整合素阻断抗体消除了 uPAR/β1 整合素介导的 H1299 细胞对纤连蛋白和 vitronectin 的粘附。该抗体和一种 uPAR/uPA 拮抗剂抗体在抑制通过 Matrigel/Collagen I 或 Collagen I 基质的细胞侵袭方面显示出显著的协同作用。我们的结果表明，这些拮抗抗体具有用于检测和治疗表达 uPAR 的肿瘤的潜力。
