In bone androgens and estrogens exert profound osteoprotective effects. Cul
tured human osteoblast (hOB)-like cells are able to metabolize circulating
androgens or androgen precursors, such as testosterone and androstenedione,
respectively, by aromatization (aromatase). 5 alpha -reduction (5 alpha -r
eductase) and reduction/oxidation at the 17 beta -position (17-beta -hydrox
ysteroid dehydrogenases, 17 beta -HSDs). In this study it was demonstrated
that cultured normal human osteoblast-like cells as well as the osteosarcom
a cell lines HOS and MG 63 express 17 beta -HSDs types 1. 2, 3 and 4. (C) 2
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