Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P61278 (somatostatin)
 22,083 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tumor-specific uptake of the radiolabeled nor-epinephrine analogue meta-iodobenzylguanidine via norepinephrine transporter or radiolabeled somatostatin analogues octreotide/octreotate via somatostatin receptors offers possibilities to diagnose and treat metastatic pheochromocytoma/paraganglioma. High uptake of 123I-meta-iodobenzylguanidine is dependent on high expression of vesicular monoamine transporters responsible for mediating uptake of biogenic amines into dense core granules. A patient with metastatic paraganglioma (liver and bone metastases) underwent surgical removal of the primary after injection of 131I-meta-iodobenzylguanidine and 111In-octreotide. Radioactivity was determined in biopsies from tumor and normal tissue biopsies. The tumor/blood concentration value was high: 180 for 131I-meta-iodobenzylguanidine 3 h after injection and 590 for 111In-octreotide 27 h after injection. Studies of primary tumor cell cultures demonstrated increased cell membrane binding and internalization over time for 131I-meta-iodobenzylguanidine. The vesicular monoamine transporter antagonist reserpine and the norepinephrine transporter inhibitor clomipramine reduced internalization by 90% and 70%, respectively, after 46 h of incubation. The results demonstrated increased cell membrane binding and internalization over time also for 111In-octreotide. Internalization was highest for a low concentration of 111In-octreotide. Excess of octreotide reduced internalization of 111In-octreotide with 75% after 46 h of incubation. In conclusion, uptake and tumor/blood concentration values of radiolabeled meta-iodobenzylguanidine and somatostatin analogues can be determined for metastatic pheochromocytoma/paraganglioma to evaluate the possibility to use one or both agents for therapy. For this patient, the high tumor/blood values clearly demonstrated that therapy using both radiopharmaceuticals would be most beneficial. In vitro studies verified specific cell-membrane binding and internalization in tumor cells of both radiopharmaceuticals.
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PMID:Specific binding and uptake of 131I-MIBG and 111In-octreotide in metastatic paraganglioma--tools for choice of radionuclide therapy. 2256 95

Pheochromocytoma is a rare but potentially lethal chromaffin cell tumor with currently no effective treatment. Peptide hormone receptors are frequently overexpressed on endocrine tumor cells and can be specifically targeted by various anti-tumor peptide analogs. The present study carried out on mouse pheochromocytoma cells (MPCs) and a more aggressive mouse tumor tissue-derived (MTT) cell line revealed that these cells are characterized by pronounced expression of the somatostatin receptor 2 (sst2), growth hormone-releasing hormone (GHRH) receptor and the luteinizing hormone-releasing hormone (LHRH) receptor. We further demonstrated significant anti-tumor effects mediated by cytotoxic somatostatin analogs, AN-162 and AN-238, by LHRH antagonist, Cetrorelix, by the cytotoxic LHRH analog, AN-152, and by recently developed GHRH antagonist, MIA-602, on MPC and for AN-152 and MIA-602 on MTT cells. Studies of novel anti-tumor compounds on these mouse cell lines serve as an important basis for mouse models of metastatic pheochromocytoma, which we are currently establishing.
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PMID:Anti-tumor effects of peptide analogs targeting neuropeptide hormone receptors on mouse pheochromocytoma cells. 2326 37

The new positron emission tomography (PET/CT) methods for neuroendocrine tumors detection are presented and compared with classic, conventional methods. Conventional methods use a gamma scintillation camera for patients with neuroendocrine tumor imaging, after intravenous injection of one of the following radiopharmaceuticals: 1) somatostatin analogues labeled with indium-111 (111In-pentetreotide) or technetium-99m (99mTc-EDDA/HYNIC-TOC); 2) noradrenaline analogue labeled with iodine-131 or -123 (131/123I-MIBG); or 3) 99mTc(V)-DMSA. Contemporary methods use PET/CT equipment for patients with neuroendocrine tumor imaging, after intravenous injection of pharmaceuticals labeled with positron emitters [fluorine-18 (18F), galium-68 (68Ga), or carbon-11 (11C)]: 1) glucose analogue (18FDG); 2) somatostatin analogue (68Ga-DOTATOC/68Ga-DOTATATE/68Ga-DOTANOC); 3) aminoacid precursors of bioamines: [a) dopamine precursor 18F-DOPA (6-18F-dihydroxyphenylalanine), b) serotonin precursor 11C-5HTP (11C-5-hydroxytryptophan)]; or 4) dopamine analogue 18F-DA (6-18F-fluorodopamine). Conventional and contemporary (PET/ CT) somatostatin receptor detection showed identical high spe- cificity (92%), but conventional had very low sensitivity (52%) compared to PET/CT (97%). It means that almost every second neuroendocrine tumor detected by contemporary method cannot be discovered using conventional (classic) method. In metastatic pheochromocytoma detection contemporary (PET/ CT) methods (18F-DOPA and 18F-DA) have higher sensitivity than conventional (131I/123I-MIBG). In medullary thyroid carcinoma diagnostics contemporary method ([18F-DOPA) is more sensitive than conventional 99mTc(V)-DMSA method, and is similar to 18FDG, computed tomography and magnetic resonance. In carcinoid detection contemporary method (18F-DOPA) shows similar results with contemporary somatostatin receptor detection, while for gastroenteropancreatic neuroendocrine tumors it is worse. To conclude, contemporary (PET/CT) methods for somatostatin receptor detection (68Ga-DOTATOC/-NOC/-TATE) in neuroendocrine tumors are much more sensitive (almost twice) and more accurate than conventional. Therefore the classical methods should be urgently replaced by contemporary methods.
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PMID:[Contemporary nuclear medicine diagnostics of neuroendocrine tumors]. 2584 63

Metaiodobenzylguanidine (MIBG) is structurally similar to the neurotransmitter norepinephrine and specifically targets neuroendocrine cells including some neuroendocrine tumors. Iodine-131 (I-131)-labeled MIBG (I-131 MIBG) therapy for neuroendocrine tumors has been performed for more than a quarter-century. The indications of I-131 MIBG therapy include treatment-resistant neuroblastoma (NB), unresectable or metastatic pheochromocytoma (PC) and paraganglioma (PG), unresectable or metastatic carcinoid tumors, and unresectable or metastatic medullary thyroid cancer (MTC). I-131 MIBG therapy is one of the considerable effective treatments in patients with advanced NB, PC, and PG. On the other hand, I-131 MIBG therapy is an alternative method after more effective novel therapies are used such as radiolabeled somatostatin analogs and tyrosine kinase inhibitors in patients with advanced carcinoid tumors and MTC. No-carrier-aided (NCA) I-131 MIBG has more favorable potential compared to the conventional I-131 MIBG. Astatine-211-labeled meta-astatobenzylguanidine (At-211 MABG) has massive potential in patients with neuroendocrine tumors. Further studies about the therapeutic protocols of I-131 MIBG including NCA I-131 MIBG in the clinical setting and At-211 MABG in both the preclinical and clinical settings are needed.
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PMID:Current Consensus on I-131 MIBG Therapy. 3010 Sep 38