Somatostatin receptor sst1–sst5 expression in normal and neoplastic human tissues using receptor autoradiography with subtype-selective ligands

摘要: Somatostatin receptors are known to be expressed in a large number of human tumours and represent the basis for vivo tumour targeting. Stable somatostatin derivatives such as octreotide or lanreotide most frequently used radiopharmaceuticals acting through specific binding receptors; however, they do not bind with high affinity all five receptor subtypes. Whereas mRNAs subtypes have been detected tumours, it is cases unclear which subtype proteins expressed. Since vitro methods close correlates predictors peptide targeting, we took advantage recently developed subtype-selective analogues evaluated approximately 200 their protein expression assays using autoradiography 125I-[Leu8, D-Trp22, Tyr25]-somatostatin-28 displacement by analogues. The majority tested neuroblastomas, meningiomas, medulloblastomas, breast carcinomas, lymphomas, renal cell paragangliomas, small lung carcinomas hepatocellular predominantly sst2. prostate sarcomas preferentially sst1, while inactive pituitary adenomas displayed sst3 and, lesser extent, Growth hormone-secreting sst2 sst5; gastroenteropancreatic phaeochromocytomas and/or sst1. Non-neoplastic tissues vessels, nerve plexus, pancreatic islets, prostatic stroma, adrenal medulla, spleen germinal centres lymphoid However, gastric mucosa sst1 colonic Interestingly, minority showed strong binding, less than 50% could displaced sum This observation suggests existence an yet unknown selected tumours. study first report analyse methods. We conclude that sst2, current Octreoscan, Fewer types (sarcomas, cancers, adenomas) express another subtype. information importance regard clinical applications development distinct selectivities.