Smith, Carolyn Margaret; (1994) Characterisation of androgen metabolism and 5α-reductase activity in human prostate cells in vitro. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

Androgen metabolism was investigated in the human prostate cancer cell lines (HPC-36M, DU145, PC-3/MA2 and LNCaP), BPH tissue slices, BPH cell suspensions and primary cultures of epithelium and stroma with the aim of developing in vitro systems for the study of androgen metabolism and for evaluating the effects of inhibitors of 5α-reductase. Pathways of testosterone metabolism were characterised by identifying metabolites produced after incubation of cells with [3H]-testosterone. BPH slices, cell suspensions, HPC-36M and DU145 formed predominantly dihydrotestosterone (DHT) via 5α-reductase. In contrast, PC-3/MA2 formed androstenedione, while LNCaP formed only testosterone-glucuronide. LNCaP was the only cell line whose growth and colony-forming ability was stimulated by testosterone and DHT. COS cells expressing 5α-reductase 1 and 2 cDNAs were used as sources of 5α-reductase isozymes. COS cell expressed 5α-reductase isozymes differed in their optimum pH and sensitivity to the inhibitors finasteride, SKF 105,657, 4-MA and UK117,026. These compounds were used to characterise the DHT-forming activity in prostate cancer cell lines, BPH tissue slices, BPH cell suspensions and BPH primary cultures. The properties of the 5α-reductase activity in HPC-36M and DU145, resembled those of 5α-reductase 1, while the properties of 5α-reductase activity in BPH cells resembled those of 5α-reductase 2. When human BPH epithelium and stroma were cultured separately, proliferation of the epithelium was accompanied by a gradual decrease in the production of DHT. However, preliminary results from studies with 5α-reductase inhibitors indicated that cultured epithelial cells lose the expression of 5α-reductase 2 activity. In contrast, fibroblast cultures converted testosterone to androstenedione and only low levels of DHT were detected. BPH cell suspensions and tissue slices represent useful systems for studying 5α-reductase 2 activity while DU145 and HPC-36M provide opportunity to investigate 5α-reductase 1. The low level of 5α-reductase activity in cultured cells may indicate the importance of cell-cell interactions in maintaining 5α-reductase expression.

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