We monitored both chromogranin A (CgA) and neuron specific enolase (NSE) in serial serum specimens from 14 patients with prostate cancer (CAP patients) showing resistance to hormonal treatment. Elevated serum CgA was detected in 10 out of these 14 patients (71%) during treatment, and an early appearance of elevated serum CgA was found in 6 of 14 (43%) of these patients when serum tPSA levels were still in the normal range. If patients with radical prostatectomy were not included, the percentage of patients showing an early appearance of elevated serum CgA would have been much higher. Elevated serum CgA levels also were found in patients not subject to hormonal therapy. Serial specimens from two out of three prostate cancer patients, randomly selected, contained elevated serum CgA. Serum NSE was not detectable in any of the serial specimens we studied, suggesting that CgA, not NSE, should be used as a marker for neuroendocrine differentiation. We also compared the serum CgA in random serum specimens between patients with BPH (benign prostate hyperplasia) and with prostate cancer in the concentration range of serum tPSA between 3–15 ng/mL. Although serum CgA concentrations in BPH patients overlapped considerably with those levels in patients with prostate cancer, levels > 100 ng/mL should suggest prostate cancer. The early appearance of elevated serum CgA allows an early change of therapy to be made and can lead to the effective prevention of any further development of metastases. J. Clin. Lab. Anal. 12:20–25, 1998. © 1998. Wiley‐Liss, Inc.

We have developed an assay specific for the PSA‐ACT (PSA‐α1‐antichymotrypsin) complex that effectively diminishes the problem of high assay background commonly reported by other investigators. The assay follows a two‐site ELISA format. Polyclonal anti‐PSA antibodies were coated on the microplate to capture the PSA complex from the serum, whereas the biotinylated anti‐ACT polyclonal antibodies and HRP‐conjugated streptavidin were used for detection. The high background ordinarily associated with this assay was greatly reduced when milk casein was added in addition to albumin for blocking and when the Super Block™ was also included in the diluents for sample dilution and dilution of enzyme conjugated detecting antibodies. The assay has a sensitivity of 0.05 ng/mL. The within‐run precision ranges from 4.2–7.2% and the between‐run precision falls between 5.8–8.5%. Cross reactions with ACT and free PSA (fPSA) are 0.0001% and 0.02%, respectively. The highest concentration of PSA‐ACT complex in the maternal sera was < 0.4 ng/mL by this assay, much less than reported in the literature. Using this improved assay, the sum of fPSA and PSA‐ACT concentrations were less than that of their corresponding total PSA (tPSA) most of the time. We believe that this improved assay should be used to replace the current tPSA assay for screening, monitoring, and managing patients with prostate cancer. J. Clin. Lab. Anal. 12:14–19, 1998. © 1998. Wiley‐Liss, Inc.

We have established a procedure for the production of milligrams of free PSA (fPSA) from LNCaP cells derived from a human carcinoma of the prostate. By growing LNCaP cells in a serum‐free medium in the presence of a synthetic androgen (R1881) and taking advantage of the special design of the Micro‐mouse Hollow Fiber Bioreactor, relatively pure fPSA could be obtained. We found that columns containing either Sephacryl S‐100 or S‐200 could be used to remove the small amount of bovine serum albumin (BSA) and PSA‐α1‐antichymotrypsin complex (PSA‐ACT) from the preparation. More than 90% of the PSA from LNCaP cell cultures are fPSA. Like fPSA from seminal plasma, two fractions of fPSA differing in protease activity can be separated by DEAE‐Sepharose chromatography. Based on the band pattern exhibited on the Western blot following sodium dodecyl sulfate‐polyacrylamide electrophoresis separation, fPSA from LNCaP contains more inactive PSA isoforms. This was confirmed by chromatofocusing: the isoelectric point (pI) of the major PSA isoforms from the LNCaP cell culture were higher (6.8 and 6.6) than that (6.4 and 6.1) of fPSA from seminal fluid. We conclude that the LNCaP cell culture is a reliable source for obtaining large quantities of pure fPSA both for the preparation of assay calibrators and controls and for studying the difference in fPSA between benign prostate disease and prostate cancer. J. Clin. Lab. Anal. 12:6–13, 1998. © 1998. Wiley‐Liss, Inc.