Prostate-specific membrane antigen (PSMA) enzyme activity is elevated in prostate cancer cells.
BACKGROUND
Prostate-specific membrane antigen (PSMA) is a glutamate carboxypeptidase that cleaves terminal carboxy glutamates from both the neuronal dipeptide N-acetylaspartylglutamate (NAAG) and gamma-linked folate polyglutamate. The prostate enzyme has activity in both the membrane and cytosolic fractions termed PSMA and PSMA', respectively.


METHODS
Using a NAAG hydrolytic radioenzymatic assay, we quantitated the enzymatic activity of PSMA and PSMA' in normal, benign prostatic hyperplasia (BPH), and prostate cancer (PC) tissues from radical prostatectomies. PSMA enzyme activity was evaluated in each tissue type and expressed per milligram protein and epithelial cell content.


RESULTS
PSMA and PSMA' enzyme activities were significantly elevated in prostate cancer when compared to normal prostate tissue and BPH. Ratios of PSMA to PSMA' were also decreased in BPH as compared to cancerous and normal tissue.


CONCLUSIONS
Prostate carcinogenesis is associated with an elevation in PSMA and PSMA' enzyme activity. In contrast, no such enhancement in PSMA activity is observed with benign neoplastic changes in BPH. Thus, the enhancement observed in prostate cancer is not simply related to a generalized prostatic hyperplasia, but is specific to its malignancy.
Lapidus
R G
RG
Guilford Pharmaceuticals, Inc., Baltimore, Maryland 21224, USA.
Tiffany
C W
CW
Isaacs
J T
JT
Slusher
B S
BS
D000954:Antigens, Surface; D002268:Carboxypeptidases / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology; D003600:Cytosol / Q000201:enzymology; D004151:Dipeptides / Q000378:metabolism; D043425:Glutamate Carboxypeptidase II; D006801:Humans; D008297:Male; D011467:Prostate / Q000201:enzymology; D011468:Prostatectomy; D011470:Prostatic Hyperplasia / Q000201:enzymology; D011471:Prostatic Neoplasms / Q000201:enzymology* / Q000601:surgery
D000954:Antigens, Surface; D004151:Dipeptides; C027172:isospaglumic acid; D002268:Carboxypeptidases; C473848:FOLH1 protein, human; D043425:Glutamate Carboxypeptidase II