Preliminary studies on the isolation and characterization of predominant prostatic proteins

BACKGROUND The increasing incidence of prostate cancer demands that we give our full attention not only to the etiology and prevention of this common type of cancer, but also to the diagnosis and prognostic course of this disease. In an effort to develop new prostatic tumor markers that could be useful to the physician at the current state of our knowledge in the diagnosis and prognosis of this disease, our laboratories have undertaken an effort to isolate and characterize the nature of the major proteins in the normal prostate and in prostatic neoplasia. METHODS In this preliminary study, tissue was obtained from open prostatic surgery in patients with a pre‐ and postoperative diagnosis of benign prostatic hyperplasia. The initial fractionation and separation of the proteins was achieved through the use of ultrafiltration of homogenates followed by SDS‐PAGE. Initial analysis of four prominent protein bands was accomplished by amino acid sequencing, and identified by a search in GeneBank data base. RESULTS Two proteins previously identified in prostatic tissue were prostate specific antigen (Mr 26,496) with 240 amino acid residues and β‐inhibin (Mr 10,704) with 94‐amino acid residues. A third protein was identified as human cysteine rich protein (hCRP). This protein functions as a DNA binding protein and has previously been postulated to contain four putative zinc fingers and to play a fundamental role in cellular function. Ubiquitin, the fourth major protein identified was a 76‐amino acid polypeptide whose function is to target other proteins for destruction. CONCLUSIONS hCRP and ubiquitin are reported as being found in high levels in prostatic tissue for the first time. © 1996 Wiley‐Liss, Inc.