Insulin-like growth factor (IGF)-I, -II and IGF-binding proteins in the cyst fluid of a patient with astrocytoma.
Insulin-like growth factor (IGF)-I, -II and IGF-binding proteins (IGFBPs) were demonstrated in the cyst fluid of a patient with a hypothalamic astrocytoma. The astrocytoma cyst fluid was subjected to gel chromatography at low pH and the IGF-I and IGF-II levels were measured by specific radioimmunoassays. Immunoreactive IGF-I and IGF-II levels were 19 ng/ml and 78 ng/ml respectively. Several-fold higher IGF-II values were obtained when cyst fluid was not extracted or was extracted with acid ethanol before radioimmunoassay analysis. The immunoreactive IGFBP-1 concentration was 26 ng/ml. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and subsequent Western ligand blotting with [125I]IGF-II revealed bands at approximately 200, 34.5, 29.5, 24 and 21 kD as visualized by autoradiography. Binding studies demonstrated that these binding proteins bind specifically [125I]IGF-I and [125I]IGF-II. These observations suggest that IGFs as well as IGF-binding proteins are produced by astrocytoma cells and may act in a paracrine or autocrine fashion capable of modulating the growth of astrocytoma tumours.
Zumkeller
W
W
Department of Endocrinology, Karolinska Hospital and Institute, Stockholm, Sweden.
Sääf
M
M
Rähn
T
T
D015153:Blotting, Western; D002352:Carrier Proteins / Q000032:analysis*; D002675:Child, Preschool; D002850:Chromatography, Gel; D005909:Glioblastoma / Q000737:chemistry* / Q000601:surgery; D006131:Growth Inhibitors / Q000032:analysis*; D006801:Humans; D007029:Hypothalamic Neoplasms / Q000737:chemistry* / Q000601:surgery; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D007335:Insulin-Like Growth Factor II / Q000032:analysis*; D008297:Male; D011863:Radioimmunoassay
D002352:Carrier Proteins; D006131:Growth Inhibitors; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II