Characterization of insulin-like growth factor II receptors in human small cell lung cancer cell lines.
Small cell lung cancer (SCLC) cell lines were investigated for the expression of insulin-like growth factor (IGF) II receptor by means of radioreceptor assays, cross-linking techniques, and Northern blot analysis. 125I-IGF II binds to both the IGF I and the IGF II receptor on intact SCLC cells. Detailed receptor assays performed on microsomal and plasma membranes gave evidence that 125I-IGF II binds with high affinity (70-80 pM) to the IGF I receptor and with low affinity (2-4 nM) to the IGF II receptor, and not conversely. The presence of mannose-6-phosphate enhanced the binding of 125I-IGF II to the IGF II receptor of SCLC. Mannose-6-phosphate also increased the efficiency of N-hydroxysuccinimide ester in cross-linking 125I-IGF II to the IGF II receptor and facilitated the cross-linking of 125I-IGF II to a second protein of 240-250 kDa. Soluble IGF II receptor was also detected in conditioned media of SCLC cell lines.
Schardt
C
C
Department of Internal Medicine, Marburg, Germany.
Rotsch
M
M
Erbil
C
C
Göke
R
R
Richter
G
G
Havemann
K
K
D015152:Blotting, Northern; D018288:Carcinoma, Small Cell / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003432:Cross-Linking Reagents; D017077:Culture Media, Conditioned; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D008175:Lung Neoplasms / Q000378:metabolism*; D008861:Microsomes / Q000648:ultrastructure; D011869:Radioligand Assay; D017527:Receptor, IGF Type 2 / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D003432:Cross-Linking Reagents; D017077:Culture Media, Conditioned; D017527:Receptor, IGF Type 2; D007334:Insulin-Like Growth Factor I