Comparison of prostate specific antigen, prostate specific membrane antigen, and LNCaP‐based enzyme‐linked immunosorbent assays in prostatic cancer patients and patients with benign prostatic enlargement

Abstract

Serum assays for prostate specific antigen (PSA; monoclonal), for prostate specific membrane antigen (PSM; Western blot), and a LNCaP/7E11.C5-based competitive enzyme-linked immunosorbent assay (ELISA) were evaluated in a small number of prostate cancer patients with localized or disseminated disease, and judged to be in clinical progression or remission based on National Prostate Cancer Project (NPCP) criteria. PSA values recognized the presence of clinical progression in localized disease (B1-C) and to a lesser degree disseminated disease (D1-D2). In contrast, to a limited degree the ELISA test recognized clinical progression mainly in disseminated disease and chiefly in stage D2. PSM values were elevated in both D1 and D2 but not in a linear fashion as observed with PSA. The ELISA and PSM results may be assessing a different clinical response to prostatic cancer than that recognized by PSA. This could reflect a developing clone of resistant prostatic cells as previously postulated. To further pursue this possibility a secondary generation of monoclonal antibodies to PSM is being developed. The ELISA levels for benign prostatic enlargement were not elevated above normal. In contrast both with PSA and PSM the assays reflected levels significantly above the normal range in benign prostatic hypertrophy (BPH).

Prostate specific membrane antigen expression in prostatic intraepithelial neoplasia and adenocarcinoma

“…These findings differ from serum studies in which elevated concentration of PSM and PSA indicated surgical treatment failure. 5,10,11 Individual cells in poorly differentiated carcinoma produce less PSA than cells in well differentiated and moderately differentiated carcinoma, but usually are present in such large numbers (greater tumor volume) and replace more of the prostate that serum PSA concentration is higher. Given the greater expresssion of PSM per cancer cell with increasing grade, we expect greater amplification of serum concentration with this marker than with PSA.…”

Generation of a Baculovirus Recombinant Prostate-Specific Membrane Antigen and Its Use in the Development of a Novel Protein Biochip Quantitative Immunoassay

“…In prostate, PSMA appeared to be downregulated in benign prostatic hyperplasia (BPH) and overexpressed in poorly differentiated primary tumors, with the highest expression in bone and lymph node metastatic prostate carcinomas, especially in patients who relapsed after androgen deprivation therapy (6,10,11). Besides its expression in prostate tissue, PSMA was also detected in body fluids, i.e., serum and seminal plasma by Western blot analysis, with the highest level in patients with late-stage prostate cancer (4,(12)(13)(14). These results suggest that PSMA activity is inversely correlated with androgen 1 This study was supported in part by grants from the National Cancer Institute (CA85067), the Virginia Prostate Center, and Cytogen Corporation.…”

Improvement of prostate cancer screening by determination of the ratio free/total PSA in addition to PSA levels

“…PSA has proven to be a valuable marker for prostatic cancer, both in the early detection and screening, as well as post-treatment follow-up [4,9,10]. However, because PSA is not a prostate cancer specific protein, considerable overlap exists between the levels of the serum PSA concentration in patients with benign prostatic enlargement and those in prostate cancer patients [11].…”