Somatostatin receptor type 2 and type 5 (SSTR2/5)

Somatostatin receptor type 2 (SSTR2) and type 5 (SSTR5) are G protein-coupled receptors that mediate the inhibitory effects of the hormone somatostatin on various physiological processes. These receptors are primarily expressed in the pituitary gland, pancreas, and gastrointestinal tract, where they regulate the secretion of hormones such as growth hormone, insulin, and glucagon (UniProt P30874, P35346). In the context of disease, SSTR2 and SSTR5 are frequently overexpressed in neuroendocrine tumors (NETs) and pituitary adenomas, serving as both diagnostic markers and therapeutic targets (PubMed PMID: 25353138). Therapeutic intervention typically involves somatostatin analogs (SSAs) like octreotide and lanreotide, which have high affinity for SSTR2, or pasireotide, which targets multiple receptors including SSTR5 with high affinity (StatPearls NBK534850). These drugs work by inducing receptor-mediated signaling that inhibits hormone hypersecretion and exerts anti-proliferative effects on tumor cells. Additionally, SSTR2 is the primary target for peptide receptor radionuclide therapy (PRRT), using radiolabeled peptides like 177Lu-DOTATATE to deliver targeted radiation to malignant tissues (PubMed PMID: 28658583). Clinical management of patients often involves monitoring SSTR expression through functional imaging, such as 68Ga-DOTATATE PET/CT, to predict treatment response. Safety considerations for targeting these receptors include the risk of gallstone formation and potential disturbances in glucose metabolism, especially hyperglycemia associated with SSTR5 inhibition (PubMed PMID: 24459236).

Other names

SSTR2SSTR5SST2SST5Somatostatin receptor 2Somatostatin receptor 5SS2RSS5R

Agonism of SSTR2 and SSTR5 receptors activates inhibitory G-proteins (Gi), which leads to the inhibition of adenylyl cyclase, a reduction in intracellular cyclic AMP (cAMP) levels, and the modulation of potassium and calcium channels, ultimately suppressing hormone release and inhibiting tumor cell proliferation (PubMed PMID: 10448905).