SOMATOSTATIN RECEPTORS IN PROSTATE TISSUES AND DERIVED CELL-CULTURES,AND THE IN-VITRO GROWTH-INHIBITORY EFFECT OF BIM-23014 ANALOG

We investigated somatostatin receptors (SSTRs) in surgical specimens o f prostate cancer and benign prostate hyperplasia (BPH), a normal immo rtalized epithelial cell line (PNT1), epithelial cancer cell lines, an d stromal cells in short-term culture derived from normal and BPH biop sies. Cross-linking studies with I-125-Tyr(11)-SRIF-14 (I-125-SRIF) an d the SRIF analog I-125-BIM-23014 identified one major 57-kDa band bot h in surgical specimens and in epithelial and stromal cells cultures. In membrane-enriched fractions and whole stromal cells from a normal p rostate and from one BPH, a single type of SSTR was characterized (K-d = 6.10(-9) and 10(-8) M, respectively, Bmax = 1.6 pmol per mg of prot eins). mRNA for SSTR1 was detected in all epithelial and stromal cells tested except for PNT1, while SSTR2 mRNA was detected in one BPH stro mal cell culture. BIM-23014 had no effect on the in vitro growth of th e epithelial cells tested. Conversely, 10(-10) M BIM-23014 induced > 5 0% growth inhibition of stromal cells after 6 days in culture. These r esults may have implications for therapeutic strategies using SRIF ana logs in BPH and prostate cancer.