Stimulation of Bone Resorption in vitro by Synthetic Transforming Growth Factor-Alpha

Experiments were conducted to test the hypothesis that tumor-derived transforming growth factor-alpha (TGF-α ) is responsible for the increased bone resorption and hypercalcemia seen in some malignant diseases. Homogeneous synthetic TGF-α prepared by the solid-phase synthesis method stimulated bone resorption directly in vitro in a concentration-dependent manner. Incubation times of 72 hours or more were required to stimulate resorption, which is similar to the time course of bone resorption by epidermal growth factor.