RESUMO
The growth and motility factor Hepatocyte Growth Factor/Scatter Factor (HGF/SF) and its receptor, the product of the MET proto-oncogene, promote invasion and metastasis of tumor cells and have been considered potential targets for cancer therapy. We generated a new Met-blocking antibody which binds outside the ligand-binding site, and determined the crystal structure of the Fab in complex with its target, which identifies the binding site as the Met Ig1 domain. The antibody, 107_A07, inhibited HGF/SF-induced cell migration and proliferation in vitro and inhibited growth of tumor xenografts in vivo. In biochemical assays, 107_A07 competes with both HGF/SF and its truncated splice variant NK1 for MET binding, despite the location of the antibody epitope on a domain (Ig1) not reported to bind NK1 or HGF/SF. Overlay of the Fab-MET crystal structure with the InternalinB-MET crystal structure shows that the 107_A07 Fab comes into close proximity with the HGF/SF-binding SEMA domain when MET is in the "compact", InternalinB-bound conformation, but not when MET is in the "open" conformation. These findings provide further support for the importance of the "compact" conformation of the MET extracellular domain, and the relevance of this conformation to HGF/SF binding and signaling.
Assuntos
Anticorpos Bloqueadores/isolamento & purificação , Anticorpos Bloqueadores/metabolismo , Antineoplásicos Imunológicos/isolamento & purificação , Antineoplásicos Imunológicos/metabolismo , Proteínas Proto-Oncogênicas c-met/metabolismo , Animais , Anticorpos Bloqueadores/administração & dosagem , Anticorpos Bloqueadores/química , Antineoplásicos Imunológicos/administração & dosagem , Antineoplásicos Imunológicos/química , Sítios de Ligação , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Cristalografia por Raios X , Modelos Animais de Doenças , Glioblastoma/tratamento farmacológico , Xenoenxertos , Humanos , Fragmentos Fab das Imunoglobulinas/administração & dosagem , Fragmentos Fab das Imunoglobulinas/química , Fragmentos Fab das Imunoglobulinas/isolamento & purificação , Fragmentos Fab das Imunoglobulinas/metabolismo , Camundongos Nus , Transplante de Neoplasias , Ligação Proteica , Conformação Proteica , Proto-Oncogene Mas , Resultado do TratamentoRESUMO
We have created a high quality phage display library containing over 1010 human antibodies and describe its use in the generation of antibodies on an unprecedented scale. We have selected, screened and sequenced over 38,000 recombinant antibodies to 292 antigens, yielding over 7,200 unique clones. 4,400 antibodies were characterized by specificity testing and detailed sequence analysis and the data/clones are available online. Sensitive detection was demonstrated in a bead based flow cytometry assay. Furthermore, positive staining by immunohistochemistry on tissue microarrays was found for 37% (143/381) of antibodies. Thus, we have demonstrated the potential of and illuminated the issues associated with genome-wide monoclonal antibody generation.