AIM: The present study adds scientific support to the growing debate regarding the superiority of radiolabeled bombesin-based antagonist peptides over agonists for molecular imaging and therapy of human tumors overexpressing the gastrin-releasing peptide receptor (GRPR) and describes a detailed in vitro and in vivo comparison of 64Cu-NODAGA-6-Ahx-BBN(7-14)NH2 agonist and 64Cu-NODAGA-6-Ahx-DPhe6-BBN(6-13)NHEt antagonist ligands.
MATERIALS AND METHODS: Conjugates were synthesized by solid-phase peptide synthesis, purified by reversed-phase high-performance liquid chromatography, and characterized by electrospray ionization-mass spectroscopy. The conjugates were radiolabeled with 64Cu.
RESULTS:In vitro and in vivo data support the hypothesis for targeting of the GRPR by these tracer molecules. Maximum-intensity micro Positron Emission Tomography (microPET) imaging studies show the agonist ligand to provide high-quality, high-contrast images with very impressive tumor uptake and background clearance, with virtually no residual gastrointestinal or renal-urinary radioactivity.
CONCLUSION: Based on microPET imaging experiments, we conclude the agonist peptide ligand to be a superior molecular imaging agent for targeting GRPR.
Written by:
Nanda PK, Wienhoff BE, Rold TL, Sieckman GL, Szczodroski AF, Hoffman TJ, Rogers BE, Smith CJ. Are you the author?
Department of Radiology, University of Missouri School of Medicine, and Harry S. Truman Memorial Veterans' Hospital, One Hospital Drive, Columbia, MO 65211, USA.
Reference: In Vivo. 2012 Jul;26(4):583-92.
PubMed Abstract
PMID: 22773572
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