Human Osteoblast-Like Cells Express Predominantly Steroid 5α-Reductase Type 1

The study investigated the expression of 5alpha-reductase (5alpha-R) isozymes in human osteoblast-like cells (hOB cells) cultured from bone, using samples from six donors. It was found that these cells predominantly expressed the type 1 isozyme, as opposed to genital skin fibroblasts, which primarily expressed type 2. The study used selective inhibitors to determine the activity of these isozymes, finding that LY191704, a type 1 inhibitor, effectively blocked 5alpha-R activity in hOB cells, while finasteride, a type 2 inhibitor, was less effective. The research suggested that local production of dihydrotestosterone (DHT) in bone, catalyzed by 5alpha-R type 1, might play a role in bone homeostasis due to the presence of androgen receptors in bone cells.