Open AccessAn Anti-Human Lutheran Glycoprotein Phage Antibody Inhibits Cell Migration on Laminin-511: Epitope Mapping of the Antibody
Author(s) -
Yurie Enomoto-Okawa,
Yuka Maeda,
Nozomi Harashima,
Yumika Sugawara,
Fumihiko Katagiri,
Kentaro Hozumi,
Kam M. Hui,
Motoyoshi Nomizu,
Yuji Ito,
Yamato Kikkawa
Publication year - 2017
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0167860
Subject(s) - epitope , microbiology and biotechnology , antibody , phage display , monoclonal antibody , biology , laminin , mimotope , periplasmic space , chemistry , biochemistry , cell , immunology , escherichia coli , gene
The Lutheran glycoprotein (Lu), also known as basal cell adhesion molecule (B-CAM), is an Ig superfamily (IgSF) transmembrane receptor for laminin α5. Although Lu is not present in normal hepatocytes, its expression is significantly increased in hepatocellular carcinoma (HCC). In this study, we isolated thirteen phage antibodies to Lu from a phage library of peripheral blood from HCC patients, suggesting that these patients produced autoantibodies against endogenous Lu. To characterize the phage antibodies, we determined the Lu domains they recognize. The extracellular domain of Lu contains five IgSF domains, D1-D2-D3-D4-D5. The epitope of one phage antibody (A7) was localized to the D5 domain. The other phage antibodies recognized the D2 domain, which is also recognized by a function blocking mouse monoclonal antibody. One of the antibodies to D2 (C7) inhibited the binding of Lu to ligand, and it also prevented tumor cell migration on laminin-511 (LM-511). However, the C7 scFv purified from the periplasm fraction of bacteria did not exhibit the inhibitory effects, indicating that the scFv form could not sterically inhibit the binding of Lu to LM-511. We also identified the amino acid residues that form the epitope recognized by the C7 phage antibody. Mutagenesis studies showed that Arg 247 is necessary for forming the epitope. The C7 phage antibody and its epitope may be useful for developing drugs to prevent HCC progression and/or metastasis.