Tamoxifen directly stimulates the mineralization of human osteoblast-like osteosarcoma cells through a pathway independent of estrogen response element.

Tamoxifen, an estrogen antagonist, stimulated the mineralization of osteoblasts in vitro in a dose-dependent manner in the presence of inorganic phosphate. The mechanism of mineralization by tamoxifen was different from that by 1 alpha, 25-dihydroxyvitamin D3. In addition, tamoxifen did not activate estrogen-response-element-mediated transcription in osteoblasts. These findings suggest that tamoxifen directly stimulates the mineralization of osteoblasts through a pathway independent of the conventional estrogen-response-element-mediated gene expression.