The Prostate zyx 21:87-97 (1992) Presence of Calcitonin-Like lmmunoreactivity (iCT) in Human Prostate Gland: Evidence for iCT Secretion by Cultured Prostate Cells Girish V. Shah, Mark J. Noble, Mark Austenfeld, John Weigel, L.J. Deftos, and Winston K. Mebust zyxwv Departments of Urologic Surgery (G. V. S., M. J. N., M. A., J. W., W. K.M.) and Physiology (G. V. zyxwvutsrq S.), University of Kansas Medical Center, Kansas City, Kansas, and Kansas City Veterans Administration Medical Center (G. V.S., M. J.N., M.A., J. W., W. K.M.), Kansas City, Missouri; Department of Medicine, University of California, San Diego and San Diego VA Medical Center, La Jolla (L.J.D.) zyxwv Immunoreactivecalcitonin (iCT) has been detected in human prostate tissue extracts as well as seminal plasma. The present studies were undertaken to examine whether iSCT (immu- noreactive salmon CT-like human peptide) co-exists with iHCT (thyroid CT-like substance) in human prostate tissue extracts, and whether these substances are secreted by primary prostate cells in culture. Since the local secretion of these substances seems to increase in some neoplasms, a second objective of the study was to examine whether basal secretion of iCTs from primary prostate cells is increased in carcinoma. The present results have shown that both iHCT and iSCT were present in prostate tissue extracts. The mean iHCT levels in extracts of benign hyperplastic prostates (BPH) were 0.59 ng/g prostate, and these were significantly lower than iHCT concentrations in prostatic carcinoma zyx (PC) (2.53 ng/g). No significant differences in their iSCT contents were observed. However, the results from culture of over 90 individual prostate tissue specimens from BPH or PC indicate that primary prostate cells secreted detectable quantities of iSCT and the basal release of this material from PC prostate cultures was almost four-fold higher than that from BPH prostate cultures. These results suggest that a CT-like immunoreactive material is secreted by primary prostate cells in culture, and the basal secretion of this material is significantly higher in PC cells as compared to BPH cells. Endogenous secretion of prostatic CT, and the elevation of its expression in PC suggest that it may serve as a regulatory factor in the pathophysiology of the prostate gland. zyxwvuts 0 1992 wiley-Liss, Inc. Key words: calcitonin, prostate cells, culture, BPH, prostatic carcinoma INTRODUCTION Calcitonin (CT), a 32-amino acid peptide hormone, is secreted by parafollicular or C cells of the thyroid gland. It inhibits bone resorption and increases renal clear- ance of sodium, phosphate and calcium [l]. In addition to CT, various related pep- Received for publication December 11, 1991; accepted April 6, 1992. Address reprint requests to Girish V. Shah, Ph.D., Department of Surgery, Division of Urology, Uni- versity of Kansas Medical Center, Rainbow Boulevard at 39th Street, Kansas City, KS 66103. 0 1992 Wiley-Liss, Inc.