title: Insulin-like growth factors, insulin, and epidermal growth factor cause rapid cytoskeletal reorganization in KB cells. Clarification of the roles of type I insulin-like growth factor receptors and insulin receptors.
abstract: Insulin-like growth factor (IGF) I (greater than or equal to 10(-10)M, insulin-like growth factor II (greater than or equal to 10(-9) M), insulin (greater than or equal to 10(-9) M, and epidermal growth factor (EGF, greater than or equal to 10(-11) M) caused rapid membrane ruffling in KB cells. The morphological change was observed within 1 min after the addition of these growth factors and was accompanied by microfilament reorganization, but not by microtubule reorganization. IGF-I, IGF-II, and insulin induced morphologically very similar or identical membrane ruffles with the order of potency IGF-I greater than IGF-II greater than insulin, whereas EGF-induced membrane ruffles were morphologically different. KB cells possessed EGF receptors, type I IGF receptors, and insulin receptors, but few or no type II IGF receptors. Monoclonal antibody against type I IGF receptors, which completely inhibited the binding of 125I-IGF-I to the cells but did not inhibit the binding of 125I-insulin, caused marked inhibition of IGF-I (10(-8) M)-stimulated membrane ruffling. IGF-II (10(-8) M)-stimulated membrane ruffling was partially inhibited in the presence of this antibody, but insulin (10(-7) M)-stimulated membrane ruffling was only slightly inhibited. In contrast, monoclonal antibody against insulin receptors blocked insulin (10(-7) M) stimulation, but not IGF-I (10(-8) M) stimulation, of membrane ruffling. Thus, this study provides evidence that IGF-I and insulin act mostly through their own (homologous) receptors and that IGF-II acts by cross-reacting with both type I IGF and insulin (heterologous) receptors in causing rapid alterations in cytoskeletal structure.
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D007328:Insulin / Q000378:metabolism / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D007335:Insulin-Like Growth Factor II / Q000494:pharmacology*; D007624:KB Cells; D011972:Receptor, Insulin / Q000276:immunology / Q000502:physiology*; D017451:Receptors, Somatomedin; D013002:Somatomedins / Q000494:pharmacology*
chemical_list: D000911:Antibodies, Monoclonal; D007328:Insulin; D017451:Receptors, Somatomedin; D013002:Somatomedins; D004815:Epidermal Growth Factor; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D011972:Receptor, Insulin