A long-term goal of research activity in this laboratory is to understand the biochemical processes by which androgens affect target organs and to provide a molecular basis for clinical manipulation of the abnormal growth and function of organs, such as the prostate, a major site of both benign and malignant growth in men. The enzyme 5alpha-reductase plays an important role in androgenic effects by converting testosterone (T) to 5alpha-dihydrotestosterone (DHT), a process believed to amplify the androgenic signal. Excessive DHT or 5alpha-reductase activity has been implicated in a variety of androgen-dependent pathological conditions including benign prostatic hyperplasia (BPH), acne, alopecia, and female idiopathic hirsutism. Inhibition of 5alpha-reductase has been advocated as a method to treat these conditions. A thorough understanding of what cells express what isozymes of 5alpha-reductase, and what factors may control their expression will provide a sound basis for pharmacological intervention in androgen-dependent disorders. Research proposed in this application extends recent discoveries concerning 5alpha-reductase, in particular the observations that 5alpha-reductase is inhibited by specific unsaturated fatty acids and that different isozymes of 5alpha-reductase may have different cellular and subcellular locations.
Specific aims i n the next 5 years are: (1) Cells and tissues expressing specific isozymes of 5alpha-reductase will be tested in vivo and in vitro for inhibition of 5alpha-reductase by a variety of fatty acids. Any differential inhibition will be defined in relation to different 5alpha- reductase isozymes or the cellular environment in which they are expressed. (2) Metabolically stable analogs of unsaturated fatty acids will be synthesized as potential inhibitors of 5alpha-reductase. 5alpha- Reductase inhibitors in plants will be isolated and structurally defined. These new 5alpha-reductase inhibitors or their derivatives have potential clinical usefulness. (3) The intracellular location of different 5alpha- reductase isozymes will be determined using specific antibody probes. Differences in cellular location will be defined in relation to the structure of 5alpha-reductase isozymes (using chimeric 5alpha-reductase expressed in cell lines deficient in this enzyme) or their cellular environment. (4) The pattern of expression of different 5alpha-reductase isozymes in different cell types of an androgen target tissue will be determined using specific antibody and cDNA/cRNA probes. Stromal and epithelial cells will be isolated and screened for expression of specific isozymes. In situ hybridization and immunocytochemical detection may provide rapid detection of isozyme expression in tissue sections. Factors (androgens, IGF-I, etc.) that contribute to cell specific expression will be studied. (5) A cell's response to T may be dependent on the particular type of 5alpha-reductase expressed in the cell. Reporter gene expression in cells expressing specific isozymes will be analyzed. The role of 5alpha-reductase in androgen-regulated gene expression will be analyzed by RNA differential display methodology to determine if T and DHT have different effects on gene expression.
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