bombesinGRPR

The gastrin-releasing peptide receptor (GRPR), also known as bombesin receptor subtype-2 (BB2), is a G protein-coupled receptor that binds bombesin-like peptides. In humans, the receptor is encoded by the GRPR gene and is part of the bombesin receptor family, which also includes receptors for neuromedin B and other related peptides.

GRPR binds gastrin-releasing peptide (GRP) with high affinity and can also interact with bombesin. Upon ligand binding, it typically engages G proteins (such as Gq/11) to trigger intracellular signaling cascades that include phospholipase C activation, calcium mobilization, and downstream pathways like MAP kinase signaling. These signals influence a range of cellular responses, including secretion, cell growth, and motility.

Expression of GRPR is widespread, occurring in certain brain regions as well as peripheral tissues such as the gastrointestinal tract, pancreas, and various organs. In the central nervous system, GRPR participates in processes including feeding, satiety regulation, and possibly nociception and learning. In peripheral tissues, it can affect smooth muscle activity, secretion in the gut, and other physiologic functions.

GRPR has drawn biomedical interest because it is overexpressed in several cancer types, including prostate, breast, and lung cancers, where it may contribute to tumor growth and angiogenesis. This has led to the development of GRPR-targeted diagnostic and therapeutic approaches, including radiolabeled ligands for PET or SPECT imaging and antagonists or agonists that may modulate receptor activity. Research continues to explore GRPR’s utility as a biomarker and a target for cancer theranostics, as well as its broader roles in physiology.