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Identification of prostate specific membrane antigen (PSMA) as the target of monoclonal antibody 107‐1A4 by proteinchip®; array, surface‐enhanced laser desorption/ionization (seldi) technology
Author(s) -
Wang Shunyou,
Diamond Deborah L.,
Hass G. Michael,
Sokoloff Roger,
Vessella Robert L.
Publication year - 2001
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.1272
Subject(s) - epitope , monoclonal antibody , microbiology and biotechnology , antigen , lncap , prostate specific antigen , immunocytochemistry , antibody , blot , biology , chemistry , immunohistochemistry , prostate cancer , biochemistry , immunology , endocrinology , cancer , genetics , gene
Recently we described the generation of the prostate tissue‐specific monoclonal antibody (MAb) 107‐1A4, its expression pattern and preliminary targeting of human prostate cancer xenografts. In this report we demonstrate that the target antigen for MAb 107‐1A4 is prostate‐specific membrane antigen (PSMA) using immunoaffinity absorption followed by SDS‐PAGE and mass spectrometric analysis of peptides produced by in‐gel tryptic digestion. The identity of the antigen has been confirmed by Western blots using MAbs of known specificity. MAb 107‐1A4 is not reactive on Western blots. The conformational epitope for 107‐1A4 is on the extracellular domain of PSMA. In competition studies, the binding of MAb 107‐1A4 to LNCaP cells is inhibited by itself but not by any other of several other anti‐PSMA MAbs, suggesting that the epitope may be unique. These results suggest that 107‐1A4 is reactive to a conformational epitope in the external domain of PSMA that is unique among the panel of anti‐PSMA MAbs in this study. Furthermore this work demonstrates the ability of mass spectroscopy to elucidate antibody‐ligand interaction. © 2001 Wiley‐Liss, Inc.