Demonstration of Insulin-Like Growth Factors I, II and Heterogeneous Insulin-Like Growth Factor Binding Proteins in the Cyst Fluid of Patients with Craniopharyngioma

Abstract

Insulin-like growth factor (IGF)-II and its binding proteins were demonstrated to be present in human craniopharyngioma cyst fluid using gel filtration and ligand blot analyses. Immunoreactive IGF-II in 3 patients was found to be 274, 232 and 310 ng/ml after gel chromatography whereas IGF-I concentrations were 13, 8 and 15 ng/ml. The IGF-II levels were severalfold higher in cyst fluid than in spinal fluid while the IGF-I levels in both fluids did not differ significantly. The binding proteins showed high affinities for [125I]IGF-II which could be displaced by unlabelled IGF-II. With the ligand blot analysis, [125I]IGF-II shows bands at 300, 175 and 46/43 kilodaltons probably representing IGF-II receptor and IGFBP-3. IGFBP-1 levels 17, 22 and 45 ng/ml, respectively, were undetectable by ligand blot.