Evidence of Steroid Receptors in Human Osteoblast-Like Cells

A nuclear binding assay was used to demonstrate steroid receptors in normal human osteoblast-like cells. Nuclear binding of [³H] estradiol was found in 27 of 30 (90%) cell strains and nuclear binding of [³H] androgen was identified in 21 of 25 (84%) separate osteoblast cell strains. The nuclear binding was saturable and steroid-specific. Estrogen and androgen receptor gene expression was confirmed by RNA blot analysis. These data suggest that circulating sex steroids may act directly on normal human osteoblasts through receptor-mediated mechanisms.