Isolation of breast cancer cell specific antibodies by whole cell selections

Phage display strategy has been used for selection of scFv antibodies that recognize cell surface tumour-associated antigens expressed in human breast cancer cells. The human naïve scFv library was first depleted with normal cell lines to remove those antibodies that bind to common cell surface epitopes. The antibody selection was not target-driven; instead selected antibodies will be used to identify new cancer related cell surface antigens which could have applications both in cancer therapy and diagnostic. 15 different scFv antibodies with preferential binding specificity towards MCF-7 breast cancer cell line have been isolated. The potential antigens will be immunoprecipitated from MCF-7 lysates with biotinylated scFvs immobilized to streptavidin coated magnetic beads and identified by mass spectrometry. We have also isolated metastasis related antibodies by using whole cell panning procedure to a pair of monoclonal cell lines that have opposite metastatic capabilities in immunocompromised mice. GD8 cell line is tumorigenic and more aggressively metastatic to the lungs than parent cell line while BD12 cell line is totally nonmetastatic but equally tumorigenic in athymic mice. Five different scFv clones binding more strongly to GD8 cell line that BD12 cell line has been isolated, and their functions and target antigens are under investigation.