Bombesin

Bombesin (BBN) is a 14-amino acid neuropeptide originally isolated from the skin of Bombina bombina. The bombesin-related family comprises three other peptides, the amphibian homologs alytesin and Neuromedin C (NMC), and the mammalian peptide named Gastrin-Releasing Peptide (GRP). Bombesin and bombesin-related peptides are characterized by a region of homology at the carboxy-terminus ending with Gly-His-Leu-Met-NH2, in which resides their biological activity. Bombesin is active in mammals and affects a broad range of biological functions including smooth muscle contraction, cell growth, blood pressure, plasma glucose, as well as gastric secretions2. These effects are mediated by the interaction of Bombesin peptide with G protein-coupled receptors (GPCRs) called bombesin receptors that are well represented in the gastrointestinal tract and in the central nervous system (CNS). Bombesin peptide is a potent natural agonist of the mammalian Gastrin Releasing Peptide Receptor (GRPR) also know as bombesin receptor 2 (BB2), whose endogenous ligand is the Gastrin Releasing Peptide (GRP). Bombesin has demonstrated a high affinity for human Gastrin-Releasing Peptide Receptors (hGRPR) in both human cells containing native GRP receptors and murine cells stably expressing human GRP receptors (IC50 = 0.17±0.01 nM and 0.07 ± 0.01 nM, respectively).There is increased interest in targeting the bombesin receptors to explore their roles in pathophysiological processes, and for diagnostic imaging of human cancers over-expressing Gastrin-Releasing Peptide Receptors (GRPR), such as prostate, breast, and small-cell lung carcinoma. Bombesin peptide is investigated as targeting peptide to deliver radiotracers and therapeutic agents into tumors. Moreover, many synthetic agonist analogs of the biologically active COOH terminus of bombesin-related peptides have been synthesized to develop more metabolically stable and selective ligands for Bombesin receptors.