SERUM-FREE PROSTATE-SPECIFIC ANTIGEN - ISOENZYMES IN BENIGN HYPERPLASIA AND CANCER OF THE PROSTATE

Prostate specific antigen (PSA) in serum of patients with benign prost atic hyperplasia (BPH) or prostate cancer (P-CA) not bound to alpha-1- antichymotrypsin (ACT) was analyzed by chromatofocusing. The procedure allowed the simultaneous separation of complexed and free PSA and the fractionation of the free PSA fraction into several isoenzymes. The d etection of the isoenzymes was strongly dependent on the combination o f: antibodies introduced in the applied commercially available immunoa ssays (Cobas(R) Core, Delfia(R)). Isoenzymes in sera of patients with benign prostatic hyperplasia were mainly situated in the pi range of 6 .6 to 7.3. Isoenzymes in sera of prostate cancer patients or in PSA fr om LNCAP cells were mainly situated in the pi range 7.0 to 8.3. Neuram inidase treatment of the sera shifted the isoelectric points of all th ree sources towards more basic pHs. An irregular glycosylation process in the dysplastic cells of the prostate is suggested to be the cause for the shift of the isoelectric points. The difference of isoenzyme d istribution along the pH axis is discussed as a diagnostic tool to dif ferentiate between BPH and P-CA. (C) 1995 Wiley-Liss, Inc.