CD176 single-chain variable antibody fragment inhibits the adhesion of cancer cells to endothelial cells and hepatocytes.

CD176 (Thomsen-Friedenreich antigen) is a tumor-associated carbohydrate epitope (glycotope) functionally involved in blood spread and liver metastasis of cancer cells by mediating the adhesion of cancer cells to endothelial cells and hepatocytes, respectively. CD176 could be a promising target for antitumor immunotherapy. We applied B lymphocytes obtained from mice immunized with CD176 antigen and constructed a phage display library. A positive clone of CD176 single-chain variable antibody fragment (scFv) was successfully screened from this library. The CD176 scFv was expressed in Escherichia coli and purified. The purified scFv can bind to the natural CD176 expressed on the surface of cancer cells. Furthermore, the CD176 scFv inhibits the adhesion of CD176(+) cancer cells to endothelial cells and hepatocytes. This CD176 scFv provides a basis for future development of recombinant CD176-specific antibodies that can be used in therapeutic application.