STROMAL AND EPITHELIAL-CELLS OF THE CANINE PROSTATE EXPRESS PARATHYROID HORMONE-RELATED PROTEIN, BUT NOT THE PTH PTHRP RECEPTOR/

BACKGROUND. Parathyroid hormone-related protein (PTHrP), a principal f actor in the pathogenesis of humoral hyyercalcemia of malignancy, is a lso widely expressed in many normal tissues, including human prostatic epithelial cells. The role of PTHrP in the prostate is not known, but may include regulation of cell growth and differentiation or calcium secretion into prostatic fluid. The dog is a valuable animal model fur human prostatic dis eases. The objective was to investigate the expre ssion of PTHrP and the PTH/PTHrP (type 1) receptor in primary cultures of canine stromal and epithelial prostatic cells. METHODS. Expression and secretion of PTHrP and the PTH/PTrP receptor was: measured in hom ogenous primary cultures of canine prostatic stromal and epithelial ce lls using immunochemistry, Northern blots, radioimmunoassay, RT-PCR, a nd receptor stimulation assays RESULTS. Epithelial and stromal cells e xpressed and secreted abundant PTHrP, but PTH/ PTHrP receptor expressi on was not detected in either cell type. CONCLUSIONS. PTHrP expression by stromal and epithelial prostatic cells and the absence of the PTH/ PTHrP (type I) receptor suggest that some functions previously propose d fur PTHrP in the prostate are unlikely. The separation procedure pre sented is a valuable tool for studying the role and regulation of PTHr P in the prostate. (C) 1998 Wiley-Liss, Inc.