William T. Tino

ISOLATION AND CHARACTERIZATION OF MONOCLONAL ANTIBODIES SPECIFIC FOR THE EXTRACELLULAR DOMAIN OF PROSTATE SPECIFIC MEMBRANE ANTIGEN

PURPOSE Monoclonal antibodies specific for protein epitopes of prostate specific membrane antigen (PSMA) expressed on the external surface of prostatic epithelial cells were prepared to provide material for use in the diagnosis or treatment of prostatic cancer. MATERIALS AND METHODS Mice were immunized with LNCaP cell membranes followed by purified PSMA before fusion. Hybridomas were screened by reactivity with purified PSMA. Resulting antibodies were characterized by enzyme-linked immunosorbent assay, Western blot and fluorescence-activated cell sorter analyses. RESULTS Monoclonal antibody producing hybridomas designated 3E11, 3C2, 4E10-1.14, 3C9 and 1G3 were obtained which displayed specificities for differing regions of the extracellular domain of the PSMA protein. These antibodies reacted strongly with PSMA from multiple sources and specifically stained unfixed PSMA expressing cells by flow cytometric analysis. CONCLUSIONS The antibodies obtained displayed strong reactivity and specificity for extracellular epitopes of PSMA. These antibodies will have value in future diagnostic and therapeutic applications focusing on PSMA as a target antigen.

Analysis of glycosylation of prostate-specific membrane antigen derived from LNCaP cells, prostatic carcinoma tumors, and serum from prostate cancer patients.

Prostate‐specific membrane antigen (PSMA) has been detected in human prostatic cancer tissues, serum, and seminal fluid based on Western blot data with the monoclonal antibody 7E11.C5. The reactive protein is very similar in size to that from human prostatic carcinoma LNCaP cells and corresponds to a protein with a molecular size of about 110,000 daltons. Given that PSMA is known to be a 750 amino acid protein of about 84,000 daltons, a substantial portion, perhaps 20–25% of the native molecular weight, is composed of carbohydrates.