Background: Parathyroid hormone-related protein (PTHrP), a principal factor in the pathogenesis of humoral hypercalcemia of malignancy, is also 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 for human prostatic diseases. The objective was to investigate the expression 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/PTHrP receptor was measured in homogeneous primary cultures of canine prostatic stromal and epithelial cells using immunohistochemistry, Northern blots, radioimmunoassay, RT-PCR, and receptor stimulation assays.
Results: Epithelial and stromal cells expressed and secreted abundant PTHrP, but PTH/PTHrP receptor expression 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 proposed for PTHrP in the prostate are unlikely. The separation procedure presented is a valuable tool for studying the role and regulation of PTHrP in the prostate.