ANALYSIS OF PROSTATIC FLUID - EVIDENCE FOR THE PRESENCE OF A PROSPECTIVE MARKER FOR PROSTATIC-CANCER

In an endeavor to identify marker(s) for prostatic cancer, proteins in prostatic fluids were analyzed by two-dimensional (2-D) gel electroph oresis. The fluids were obtained from five males who had no prostate l esions and five patients each with benign prostatic hyperplasia (BPH) and prostatic carcinoma (PCA). The specimens were collected directly o ver a mixture of protease inhibitors and centrifuged, and the supernat ants were lyophilized and solubilized in sodium dodecyl sulfate mix. I dentical amounts of proteins were pooled according to donors' prostate disease and the resulting samples were subjected to 2-D gel analysis employing the ISO-DALT system. The electrophoretograms were developed by silver or double stain. The samples of each group exhibited distinc tive profiles with the exception of similar relative positions of majo r protein spots. A predominant protein occurring as several charge var iants was consistently present in prostatic fluids of patients with PC A. This protein appeared to be a previously unknown constituent that w e have called protein D (molecular weight similar to 22 kDa and isoele ctric point similar to 4), and was undetectable in the fluids of ''nor mal'' men and patients with BPH. An analysis of pooled, unprocessed ur ine from PCA patients revealed that perhaps this protein is excreted i n urine in very low quantities. These results strongly suggest that th e potential of this protein as a marker for prostatic cancer should be further explored. (C) 1995 Wiley-Liss, Inc.