A new generation of monoclonal and recombinant antibodies against cell-adherent prostate specific membrane antigen for diagnostic and therapeutic targeting of prostate cancer.
BACKGROUND
Prostate-specific membrane antigen (PSMA) is an excellent candidate for targeting prostate cancer by virtue of its restricted expression on prostatic epithelial cells and its upregulation on prostatic carcinoma cells. PSMA is expressed on the cell surface displaying a specific three-dimensional structure. Therefore, only antibodies with a high cell binding activity will have an important impact on antibody-based imaging and therapy.


METHODS
Monoclonal antibodies (mAbs) and single chain antibody fragments (scFvs) were prepared from spleen cells of mice that had been immunized either with purified PSMA or a cell lysate of prostate cancer LNCaP cells containing native PSMA. mAbs and scFvs were screened for reactivity with purified PSMA and binding to PSMA-expressing LNCaP cells.


RESULTS
From mice immunized with purified PSMA, we obtained three mAbs (K7, K12, D20) and four scFvs (G0, G1, G2, G4), which were highly reactive with the isolated antigen, but showed weak or no reaction with viable LNCaP cells. From mice immunized with unpurified LNCaP lysate, we obtained three mAbs (3/E7, 3/F11, 3/A12), and one scFv (A5), which were reactive with purified PSMA, also showing a strong and specific binding to viable LNCaP cells and PSMA-transfected cells.


CONCLUSIONS
Our results suggest that only the mAbs and scFvs, that were elicited with unpurified LNCaP lysate and not with purified PSMA will be useful agents for diagnostic imaging and therapeutic applications of prostate cancer.
Elsässer-Beile
Ursula
U
Department of Urology, Experimental Urology, University of Freiburg, Freiburg, Germany. ursula.elsaesser@uniklinik-freiburg.de
Wolf
Philipp
P
Gierschner
Dorothee
D
Bühler
Patrick
P
Schultze-Seemann
Wolfgang
W
Wetterauer
Ulrich
U
D000906:Antibodies / Q000276:immunology / Q000627:therapeutic use; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000627:therapeutic use*; D000954:Antigens, Surface / Q000276:immunology*; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D004354:Drug Screening Assays, Antitumor; D043425:Glutamate Carboxypeptidase II / Q000276:immunology*; D006801:Humans; D007128:Immunoglobulin Fragments / Q000276:immunology*; D007167:Immunotherapy / Q000379:methods; D008297:Male; D017430:Prostate-Specific Antigen / Q000276:immunology*; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D011994:Recombinant Proteins / Q000276:immunology / Q000627:therapeutic use; D012680:Sensitivity and Specificity
D000906:Antibodies; D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D007128:Immunoglobulin Fragments; D011994:Recombinant Proteins; C473848:FOLH1 protein, human; D043425:Glutamate Carboxypeptidase II; D017430:Prostate-Specific Antigen