Differently labeled peptide ligands for rapid investigation of receptor expression on a new human glioblastoma cell line

The neuropeptides vasoactive intestinal peptide (VIP), neuropeptide Y (NPY) , and substance P (SP) as well as insulin and insulin-like growth factor 1 (IGF-1) were labeled with biotin, fluorescent dyes, and radioactivity to ch aracterize the expression of peptide receptor of a novel cancer cell line, established from a human glioblastoma multiforme. Thus, not only binding si tes could be detected but advantages and disadvantages of the different lab els could be compared, too. With all three markers, the presence or absence of the receptors could be answered rapidly and sensitively. The glioblasto ma cells express receptors for VIP (IC50 = 9 nM +/- 30%), insulin (K-d = 0. 66 nM +/- 14%, B-max = 0.028 nM +/- 13%), and IGF-1 (K-d = 21 nM +/- 25%, B -max = 1.65 nM +/- 24%), but there are no binding sites for NPY and SP. As especially VIP and IGF-1 receptors are expressed in huge amounts, these rec eptors might be an interesting target for tumor diagnostics and therapy. (C ) 2000 Elsevier Science Inc. All rights reserved.