Production and Characterization of High Affinity Single-Chain Antibody Fragments (scFvst) That Inhibit Breast Cancer Metastasis

摘要

We have generated high affinity, specific single chain antibodies that recognize two key components of the metastatic phenotype: urokinase-type plasminogen activator (uPA) and its cell surface receptor (uPA-R). A total of six different scFv antibodies were found for each of the two antigens. Competition ELISA assays show that 5 of the 6 anti-uPA-R scFv antibodies compete with uPA for binding to the receptor and therefore are candidates for scFv which may inhibit metastasis by disrupting the uPA:uPA-R interaction. We have also developed the technology to convert a scFv selected from a phage display library, which due to its small size has an extremely short serum half life in mouse, into a longer lived format to allow for in vivo anti-metastasis assays. We have accomplished this by creating plasmid vectors that fuse the scFv to the human IgG1 Fc domain. The resulting scFv-Fc fusion is expressed to high levels in yeast cells, retains the affinity and specificity of the parent scFv, and has a serum half life in mice of 93 hours, similar to a IgG molecule.