Stimulation of DNA synthesis by epidermal growth factor in osteoblast-like cells

Normal and malignant osteoblast-like cells in culture have been shown to possess specific, high affinity receptors for epidermal growth factor (EGF). In this study, the mitogenic response to EGF was examined in a clonal line of a rat osteogenic sarcoma (UMR 106) and in osteoblast-rich newborn rat calvarial cells. Twenty-four hour treatment of UMR 106 cells with EGF in doses ranging from 10^-12 m to 2 × 10^-8 m stimulated the incorporation of [³H]thymidine and DNA synthesis in a dose-dependent manner. This short-term stimulatory effect was sustained in long-term culture with a dose-dependent increase in cell proliferation by calvarial cells. A lag period of 8 h occurred before significant stimulation of [³H]thymidine incorporation was observed. Commitment to increased incorporation of [³H]thymidine required a minimum of 6 h continuous incubation with EGF. These results establish the osteoblast as a target cell for EGF action on bone.