title: Recombinant human transforming growth factor-alpha stimulates the formation of osteoclast-like cells in long-term human marrow cultures.
abstract: Transforming growth factor-alpha (TGF-alpha) is synthesized by a variety of tumor cell lines and stimulates osteoclastic bone resorption in vitro. The mechanism by which TGF-alpha increases osteoclast activity is unknown. We used a human marrow culture system that forms osteoclast-like multinucleated cells (MNCs) to determine the effects of recombinant human TGF-alpha on MNC formation. Addition of 0.01 ng/ml TGF-alpha for the 1st week followed by 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] for the subsequent 2 wk significantly increased MNCs. Treatment of these cultures with TGF-alpha without later addition of 1,25(OH)2D3 did not increase MNC formation. Autoradiographic studies revealed that TGF-alpha stimulated proliferation of precursors for MNCs, and 1,25(OH)2D3 increased their rate of fusion into MNCs. Addition of murine epidermal growth factor (EGF) (0.1 ng/ml) followed by 1,25(OH)2D3 also significantly stimulated MNC formation. These data suggest that TGF-alpha and EGF may stimulate bone resorption by increasing the proliferation of osteoclast precursors, which leads to increased numbers of osteoclasts.
mesh_terms: D001853:Bone Marrow / Q000187:drug effects; D001854:Bone Marrow Cells; D002117:Calcitriol / Q000494:pharmacology; D002478:Cells, Cultured; D003114:Colony-Forming Units Assay; D004305:Dose-Response Relationship, Drug; D004815:Epidermal Growth Factor / Q000494:pharmacology; D006801:Humans; D010010:Osteoclasts / Q000187:drug effects*; D010455:Peptides / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000494:pharmacology*; D013997:Time Factors; D015291:Transforming Growth Factors
chemical_list: D010455:Peptides; D011994:Recombinant Proteins; D004815:Epidermal Growth Factor; D015291:Transforming Growth Factors; D002117:Calcitriol