Benign prostatic hyperplasia (BPH) is a heterogeneous disease typified by abnormal proliferation of stromal and epithelial cells leading to diffuse hyperplasia and nodule formation. During fetal development of the urogenital sinus-prostate gland, inductive stimuli from mesenchymal cells induce and direct the growth and differentiation of epithelium. This process is androgen regulated, yet specific mechanisms are unknown. The mechanisms of such tissue-tissue interaction are likely to be relevant to abnormal processes of growth control typified by BPH. To address mechanisms, we have characterized paracrine acting factors from fetal rat urogenital sinus (UGS) organ cultures and derived mesenchymal cell lines. UGS mesenchymal cells secrete a factor (UGIF) which alters human prostatic epithelial cell phenotype, stimulates secretory protein synthesis, and inhibits proliferation, suggesting this protein functions as a differentiation-inducing factor. Physiochemical, biological and immunological properties have been determined and the UGIF protein purified to homogeneity. A variant, phenotypically transformed UGS mesenchymal cell strain (U4F1) showed decreased UGIF expression coordinate with a stimulated secretion of activated TGF-beta2 not observed in the parent cell line (U4F). UGIF acted additionally to inhibit the proliferation of UGS mesenchymal cells, suggesting an additional autocrine role. In contrast to UGIF, the TGF-betas are bimodal in action and are generally growth stimulatory to stromal cells. Mutations or alteration in UGIF expression coupled with alterations in the expression of stimulatory growth factors may produce a growth control imbalance, potentially relevant to the initiation and progression of BPH. The following studies are proposed: To develop antibody and oligonucleotide probes to UGIF; To determine the spatial and temporal expression of UGIF and TGF-beta isoforms in normal prostate and in five histological subsets of BPH tissue; To determine the primary structure of human UGIF cDNA and characterize mutational defects in BPH histological subsets by analysis of PCR amplified cDNA products encoding UGIF and; To characterize the in vitro and in vivo responses of human BPH to UGIF. Antibody and cRNA probes will be used for immunocytochemistry and in situ hybridization. The mixed oligonucleotide primed amplification procedure (MOPAC) will be used to analyze human UGIF cDNA, generate probes, and clone full length cDNA. UGIF cDNA from tissue subsets of BPH will be analyzed by PCR/GC-clamp DGGE methods and sequenced to map putative mutations. BPH organ explants exposed to purified rat UGIF +/- androgens will be analyzed for growth and marker protein expression in vitro to correlate with in vivo effects. The athymic nude mouse host system will be used with transplanted normal prostate and BPH tissue subsets with UGIF containing Alzet Micro-Osmotic pumps to assess in vivo effects in intact and castrate animals. Long range goals are to understand the mechanisms of UGIF action in normal prostate development and in abnormal growth control of the prostate gland.