Phage display selection of fully human antibody fragments to inhibit growth-promoting effects of glycine-extended gastrin 17 on human colorectal cancer cells

Publication year: 2018
Authors: Khajeh S .1,2, Tohidkia M.R. 2, Aghanejad A. 2, Mehdipour T. 2, Fathi F. 2, Omidi Y. 2

1- Department of Biology, Faculty of Science, Islamic Azad University, Urmia Branch, Urmia, Iran
2 - Research Center for Pharmaceutical Nanotechnology, Tabriz University of Medical Sciences, Tabriz, Iran

Published in: Artificial Cells, Nanomedicine and Biotechnology, 2018, Vol. 46
doi: 10.1080/21691401.2018.1478846

Glycine-extended gastrin 17 (G17-Gly), a dominant processing intermediate of gastrin gene, has been implicated in the development or maintenance of colorectal cancers (CRCs). Hence, neutralizing G17-Gly activity by antibody entities can provide a potential therapeutic strategy in the patients with CRCs. To this end, we isolated fully human antibody fragments from a phage antibody library through biopanning against different epitopes of G17-Gly in order to obtain the highest possible antibody diversity. ELISA screening and sequence analysis identified 2 scFvs and 4 VL antibody fragments. Kinetic analysis of the antibody fragments by SPR revealed KD values to be in the nanomolar range (87.9-334 nM). The selected anti-G17-Gly antibody fragments were analyzed for growth inhibition and apoptotic assays in a CRC cell line, HCT-116, which is well-characterized for expressing gastrin intermediate species but not amidated gastrin. The antibody fragments exhibited significant inhibition of HCT-116 cells proliferation ranging from 36.5 to 73% of controls. Further, Annexin V/PI staining indicated that apoptosis rates of scFv H8 and VL G8 treated cells were 45.8 and 63%, respectively. Based on these results, we for the first time, demonstrated the isolation of anti-G17-Gly human scFv and VL antibodies with potential therapeutic applications in G17-Gly-responsive tumors.

MP-SPR keywords: antibody, binding affinity and kinetics, fragments, peptide capture, streptavidin sensor