Generation and characterization of recombinant human antibodies specific for native laminin epitopes: Potential application in cancer therapy

Laminins are specific cellular regulators that directly and indirectly control activities such as cell attachment and migration, differentiation and polarity, proliferation and apoptosis, and protease expression. Considering the centrality of these issues to tumor progression, the generation of human-derived antibody fragments able to modulate laminin-regulated biological functions would allow the development of new strategies to improve treatment of cancer patients. In this report, we explore the use of phage display technology to isolate human anti-laminin antibody fragments. A library of single chain antibodies was selected using intact mouse laminin, and five different clones were identified. All the antibodies were specific for their cognate antigen, as revealed by lack of cross-reactivity with other components of the basement membranes. A more extensive characterization of the panel indicated that these antibodies recognize the native protein through conformational epitopes. All of them reduced tumor cell attachment to laminin, suggesting that domains of the laminin molecule that are recognized by these antibodies likely bind to cell-surface receptors. The antibody fragments bind to mouse, rat and human laminin, and show strong immunohistochemical reactivity with basement membranes in human and murine tissue sections. Their properties make them ideal candidates for in vivo applications.