INSULIN-LIKE GROWTH-FACTORS AND IGF BINDING-PROTEINS IN CYST FLUID FROM PATIENTS WITH CRANIOPHARYNGIOMA PRIOR TO INTRACAVITARY IRRADIATION WITH (90)YTTRIUM AND THEREAFTER

Aim-To examine a series of cyst fluid samples from patients with crani opharyngioma at various stages of treatment in order to evaluate the u se of insulin-like growth factors (IGFs) and IGF binding proteins as t umour markers or indicators of successful treatment, or both. Methods- Cyst fluid samples were obtained by stereotactic puncture prior to the intracavitary application of (90)Yttrium and at subsequent occasions. Analysis was performed by gel chromatography, radioimmunoassays, bind ing studies, and sodium dodecyl sulphate-polyacrylamide gel electropho resis (SDS-PAGE) with subsequent western blotting. Results-IGF-I, -II and IGF binding protein-1 concentrations were measured in three cranio pharyngioma cyst fluid samples. Immunoreactive IGF-I and IGF binding p rotein-1 concentrations in these three samples were between 6 and 29 n g/ml, and 17 and 48 ng/ml, respectively. In contrast, the IGF-II conce ntrations measured in 19 cyst fluid samples from seven patients with c raniopharyngioma at various stages of treatment were much higher at 25 -671 ng/ml. SDS-PAGE and subsequent western blotting using [I-125]IGF- II as the Ligand gave bands with estimated molecular weights of 330, 2 20, 135, 96, 46, 43, 34, 29, and 13.5 kDa in one adult, and identical bands at 220, 41.5, 37.5, 32, and 19 kDa in three cyst fluid samples f rom three children with craniopharyngioma. Conclusions-These results s uggest that IGFs and IGF binding proteins are secreted by craniopharyn giomas and that they may alter the growth characteristics of these tum ours. Furthermore, the distinct pattern of IGF binding protein sizes m ight be used as a tool for the differential diagnosis of tumours of th e central nervous system.