HUMAN OSTEOBLAST-LIKE CELLS CONTAIN SPECIFIC, SATURABLE, HIGH-AFFINITY GLUCOCORTICOID, ANDROGEN, ESTROGEN, AND 1-ALPHA,25-DIHDROXYCHOLECALCIFEROL RECEPTORS

Glucocorticoids, androgens, estrogens and 1 alpha,25-dihydroxycholecal ciferol (1 alpha,25-(OH)(2)D-3) exert a variety of effects on bone hom eostasis. We have measured the receptors for these hormones in culture d human osteoblast-like cells. Specific binding was found with each of the four steroids tested, namely maximum binding capacities, B-max, o f 2,581 (1,368-4,223), 146 (101-237), 176 (20-552), and 387 (290-620) fmol.mg DNA(-1) (mean, range) for [H-3]dexamethasone, [H-3]1 alpha-dih ydrotestosterone, [H-3]17 beta-estradiol ([H-3]E(2)), and [H-3]1 alpha ,25-(OH)(2)D-3, respectively. The corresponding apparent dissociation constants were 13.3(9.2-22.2), 0.43(0.23-0.94), 0.45 (0.17-0.88), and 0.020 (0.008-0.030) nM, respectively. Both high-affinity, low-capacity and low-affinity, high-capacity specific [H-3]E(2) binding were demon strable. In conclusion, we could demonstrate that human osteoblast-lik e cells contain specific glucocorticoid receptors. In addition specifi c androgen, estrogen, and 1 alpha,25-(OH)(2)D-3 binding was demonstrat ed. These cells contain several times more binding sites for dexametha sone than for dihydrotestosterone, estradiol, and 1 alpha,25-(OH)(2)D- 3, a feature that might contribute to the marked sensitivity of human bone to glucocorticoids.