A Novel Coculture Model for Benign Prostatic Hyperplasia Expressing Both Isoforms of 5α-Reductase¹

Abstract

We have developed a coculture system for primary fibroblast and epithelial cells derived from benign prostatic hyperplasia (BPH) that retained many of the characteristics of the intact human prostate. In contrast to separately cultured prostate fibroblast and epithelial cells, cocultures of fibroblasts and epithelial cells maintained messenger ribonucleic acid expression and functional activity for both isoenzymes of 5 alpha-reductase (type I and type II) as well as maintained expression of androgen receptors and prostate-specific antigen. Furthermore, levels of prostate-specific antigen secreted by cocultured epithelial cells were increased by treatment with androgens, mimicking the situation in the human gland. This contrasted with conventionally cultured fibroblasts or epithelial cells, which failed to express 50 alpha-reductase type II and rapidly lost expression of androgen receptors and androgen sensitivity upon being placed into culture. Electron microscopy demonstrated intracellular structures indicative of the differentiated state of the cocultured cell types, including round nuclei, tonofibrils, and microvilli in epithelial cells and elongated nuclei; large amounts of Golgi and cilia; along with immature collagen fibers in fibroblasts. The present study demonstrates that the coculture model reflects more closely the in vivo system for human BPH and is thus a far more suitable model for investigating the molecular and cellular events that underlie BPH than current in vitro systems.

Identification of androgen receptor protein and 5alpha -reductase mRNA in human ocular tissues

“…This finding appears to conflict with the results of a recent study, which reports that only type 1 transcripts may be detected in these cells 64. However, other researchers have also identified type 2 5α-reductase mRNA in cultured human prostatic epithelial cells, whether primary,42immortalised,65 or LNCaP (Van Luu-The, Quebec, Canada, personal communication). The extent of this mRNA expression is apparently very dependent upon the nature of the culture conditions (Luu-The, personal communication) 42…”

“…Their activity, in turn, is essential for the formation of potent androgen metabolites throughout the body 1820 39 40 Our observation that both types of reductase mRNA are present in the eye and adnexal tissues is not surprising, given that these enzymes are known to be transcribed and translated together in non-ocular sites 4262 However, whether both of these isozymes are translated in ocular tissues, and act to modulate androgen metabolism, has yet to be clarified.…”

Prostate epithelial cell lines form spheroids with evidence of glandular differentiation in three-dimensional Matrigel cultures

“…We hope to investigate this idea further, by increasing our panel of cells to see how Matrigel influences other undifferentiated and invasive cell lines. We would also like to investigate the influence of stroma over this system since other groups have shown that stroma is required for expression of the prostate specific genes, PSA, androgen receptor and 5α reductase (Liu et al, 1997, Bayne et al, 1998. The altered synthesis of basement membrane as a tumour progresses may be due to alter-ations in the stroma, since recent work has shown that stroma derived from tumour tissue has different in vitro qualities to that derived from non-tumour tissue (Lang et al, 1999;Lang et al, 2000).…”

“…Similar work with prostate epithelia has also shown the formation of acini capable of secreting prostate specific proteins (Webber et al, 1997). Studies with the prostate have further shown that stromal cells are also required for growth and functional differentiation of prostate epithelia, though the contribution of basement membranes was not established (Timms et al, 1995;Liu et al, 1997;Bayne et al, 1998).…”

Factors Controlling the Expression of 5α-Reductase in Human Prostate: A Possible New Approach for the Treatment of Prostate Cancer

“…The findings on the tissue were supported by supplementary experiments on primary cultures which demonstrated that both the fibroblast and epithelial cells maintained a capacity to express both isoenzymes in vitro [7]. In the case of the fibroblast this capacity was maintained following sequential passaging of the cells up to passage 6 following which the cells no longer expressed either isoenzyme.…”