Characterization of Insulin-Like Growth Factor I Receptors on Madin-Darby Canine Kidney (MDCK) Cell Line

Specific insulin-like growth factor I (IGF-I) receptors on the Madin-Darby canine kidney (MDCK) cell line were identified and characterized. 125IIGF-I specifically bound to the cells, but 125Iinsulin bindings to the cells was minimal. Unlabeled IGF-I displaced both the IGF-I and insulin bindings with potencies that were 100 and 10 times as great as insulin. By an affinity labeling technique, IGF type I receptors were present in the MDCK cells. IGF-I stimulated DNA synthesis and cell proliferation at physiological concentrations. On the other hand, insulin had a little effect on DNA synthesis. These data suggest that IGF type I receptors as demonstrated in MDCK cells are involved in DNA synthesis and cell proliferation.