Etiology and Pathogenesis > Insulin-like Growth Factors

Abstract

Insulin-like growth factor (IGF)-I, -II and IGF-binding proteins in the cyst fluid of a patient with astrocytoma

Zumkeller W, Saaf M, Rahn T

Department of Endocrinology, Karolinska Hospital and Institute, Stockholm, Sweden

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.

PMID: 7686451 [PubMed - indexed for MEDLINE]