text: GLP-1 receptor expression in human tumors and human normal tissues: potential for in vivo targeting.
  UNLABELLED: Peptide hormone receptors overexpressed in human tumors, such as somatostatin receptors, can be used for in vivo targeting for diagnostic and therapeutic purposes. A novel promising candidate in this field is the GLP-1 receptor, which was recently shown to be massively overexpressed in gut and lung neuroendocrine tumors--in particular, in insulinomas. Anticipating a major development of GLP-1 receptor targeting in nuclear medicine, our aim was to evaluate in vitro the GLP-1 receptor expression in a large variety of other tumors and to compare it with that in nonneoplastic tissues. METHODS: The GLP-1 receptor protein expression was qualitatively and quantitatively investigated in a broad spectrum of human tumors (n=419) and nonneoplastic human tissues (n=209) with receptor autoradiography using (125)I-GLP-1(7-36)amide. Pharmacologic competition experiments were performed to provide proof of specificity of the procedure. RESULTS: GLP-1 receptors were expressed in various endocrine tumors, with particularly high amounts in pheochromocytomas, as well as in brain tumors and embryonic tumors but not in carcinomas or lymphomas. In nonneoplastic tissues, GLP-1 receptors were present in generally low amounts in specific tissue compartments of several organs--namely, pancreas, intestine, lung, kidney, breast, and brain; no receptors were identified in lymph nodes, spleen, liver, or the adrenal gland. The rank order of potencies for receptor binding--namely, GLP-1(7-36)amide = exendin-4 >> GLP-2 = glucagon(1-29)--provided proof of specific GLP-1 receptor identification. CONCLUSION: The GLP-1 receptors may represent a novel molecular target for in vivo scintigraphy and targeted radiotherapy for a variety of GLP-1 receptor-expressing tumors. For GLP-1 receptor scintigraphy, a low-background signal can be expected, on the basis of the low receptor expression in the normal tissues surrounding tumors.
entities.id: T10 T11 T12 T13 T14 T15 T16 T17 T18 T19 T1 T2 T3 T4 T5 T6 T7 T8 T9
entities.type: GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-N GENE-Y GENE-Y GENE-Y CHEMICAL GENE-Y GENE-N GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y
entities.text: GLP-1 receptor GLP-1 receptor GLP-1 receptor GLP-1 receptor GLP-1 receptor GLP-1 receptor somatostatin receptors GLP-1(7-36) GLP-1 receptors GLP-1 receptor somatostatin GLP-1 receptors Peptide hormone receptors GLP-1(7-36) exendin-4 GLP-2 glucagon(1-29) GLP-1 receptor GLP-1 receptors