Production, characterization, and in vitro effects of a novel monoclonal antibody against Mig-7

Development of new cancer therapies based on specific recognition of molecules in cancer cells is a significant challenge, as this requires identification of such molecules (molecular targets) and subsequent development of high-affinity, selective binders (targeting molecules). While several molecular targets for cancer therapies are currently under evaluation in clinical trials, greater selectivity for cancer cells over normal cells is required to enhance efficacy. Migration-inducing gene 7 (Mig-7), a membrane protein found in various types of carcinoma cells, is a cancer-specific biomarker and a promising molecular target for targeted cancer therapies. The purpose of this study was to produce and characterize a novel monoclonal antibody (mAb) raised against an N-terminal peptide of human Mig-7 (Mig-7(1-30)). The Mig-7(1-30) peptide was conjugated with a KLH carrier protein for immunization, and the mAb specific to Mig-7 (STmAb-1) was produced using hybridoma technology. Western blot analysis showed that STmAb-1 specifically reacted with a 23-kDa Mig-7 protein expressed in cancer cell lines, and, crucially, not with primary human fibroblasts. The affinity constant (K-aff) of STmAb-1, as measured by noncompetitive enzyme immunoassay, was 1.31 x 10(9) M-1, indicating high mAb affinity against Mig-7. Immunofluorescence assays demonstrated that STmAb-1 could specifically recognize Mig-7 expressed in cancer cell lines, but not in primary human fibroblasts and keratinocytes. Moreover, STmAb-1 inhibited the growth of MCF7 and HeLa cell lines in contrast to primary human fibroblasts, highlighting its potential usefulness in the development of new cancer therapeutics. (C) 2016 Elsevier Inc. All rights reserved.