Identification of the glycosaminoglycan keratan sulfate in the prostatic secretory cell

BACKGROUND. Prostate secretory granules (PSG) represent the basic secretory unit of the prostate gland, containing many of its exocrine proteases. Rec ent analysis of intraluminal corpora amylacea, a proposed by-product of PSG secretion, detected sulfated glycosaminoglycans (GAG) possibly keratan sul fate (KS),indicating a secretory mechanism for GAG in the human prostate su rface epithelial cell. METHODS. Immunostains using anti-KS and anti-prostate-specific antigen (PSA ) were evaluated on 10 sequential radical prostatectomy specimens, three of which had received neoadjuvant antiandrogen therapy. Extracts of normal se cretory tissue as well as a sample composed almost entirely of prostatic st roma were subjected to Western blot analysis, using the same antibody panel . RESULTS. Keratan sulfate secretion from the normal prostate epithelial cell has been confirmed and correlates, as does PSA, with the presence of cytop lasmic PSG. No such correlation exists in most adenocarcinomas or in benign epithelium after androgen ablation. Western blot analyses confirmed tissue immunostains and demonstrated a secretory proteoglycan of 70-95 kDa. CONCLUSIONS. Recognition of PSG heralds a novel secretory mechanism within the human prostate gland that is linked to the secretion of KS. The role of KS in normal prostate secretion remains unknown, although it appears downr egulated in neoplastic and androgen-ablated cells. (C) 2000 Wiley-Liss, Inc .