GRPRexpressing

GRPRexpressing refers to cells or tissues that express the gastrin-releasing peptide receptor (GRPR), a member of the bombesin receptor family. GRPR is a G protein-coupled receptor that binds gastrin-releasing peptide (GRP) or bombesin and activates intracellular signaling pathways, most commonly via Gq/11 proteins leading to phospholipase C activation, inositol trisphosphate production, diacylglycerol formation, and increased intracellular calcium. The receptor plays roles in various physiological processes, including regulation of gastrointestinal motility, pancreatic and gastric secretion, and central nervous system functions such as appetite and arousal.

GRPR expression is diverse across tissues. It is found in the brain, gastrointestinal tract, pancreas, and lungs, with notable upregulation reported in several cancer types. In oncology, GRPRexpression is of interest because GRPR signaling can influence cell proliferation, migration, and survival. Tumors such as prostate, breast, lung, and colorectal cancers have shown GRPR expression, making GRPR a potential biomarker for tumor characterization and a target for diagnostic imaging and therapeutic strategies.

Detection of GRPRexpressing cells typically involves immunohistochemistry for GRPR protein, in situ hybridization for GRPR mRNA, or quantitative PCR. Radiolabeled GRPR ligands and bombesin analogs enable PET or SPECT imaging to visualize receptor distribution in vivo, and some approaches explore GRPR-targeted therapies. Challenges include variable and heterogeneous receptor expression, receptor subtypes with overlapping ligand specificity, and potential desensitization or off-target effects, which may affect clinical utility.