Insulinlike Growth Factor I: A Potent Mitogen for Human Osteogenic Sarcoma

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Abstract
Insulinlike growth factor I (IGF-I) is among the peptide mitogens that play key roles in the regulation of normal skeletal growth. To investigate the pos-sibility that certain skeletal neoplasms retain a sensitivity to mitogenic stim-ulation by IGF-I, we studied the effects of this growth factor on human osteosarcoma. Competitive-binding as-says and affinity-labeling experiments on membranes prepared from MG-63 immortalized human osteosarcoma cells and primary human osteogenic sarcoma cells demonstrate the presence of specific IGF-I receptors. Further-more, we show that IGF-I is a potent stimulator of proliferation of MG-63 cells in vitro and is active at concentrations as low as 10 −10M. abstract blocking antibody against the IGF-I receptor (α-IR3) significantly reduces IGF-I-stimulated proliferation in a dose-dependent man-ner. These results are consistent with the hypothesis that at least a subset of human osteogenic sarcomas are re-sponsive to IGF-I and indicate that it may be possible to exploit this respon-siveness therapeutically. [J Natl Cancer Inst 82: 301– 305, 1990]