Somatostatin GPCR Family Subtypes and Products

What Are Somatostatin Receptors?

Somatostatin receptors are a family of G protein-coupled receptors (GPCRs) comprised of five receptor subtypes: SST1, SST2, SST3, SST4, and SST5. These receptors are found all throughout tissue in the brain and peripheral, and are involved in a variety of biological functions such as glucagon secretion, insulin secretion, gastric acid secretion, cell proliferation, angiogenesis, and neuron activity. While more research still needs to be done to discover more subtype-specific agonists and antagonists, somatostatin receptor agonists currently have therapeutic potential in the treatment of neuroendocrine tumours.

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Somatostatin Receptor Information

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sst1

sst2

sst3

sst4

sst5

Somatostatin receptors (SSTRs) are activated by somatostatin secreted from nerve and endocrine cells. SSTRs are expressed in a tissue-specific manner and involved in the regulation of secretion of insulin, glucagon and growth hormone as well as cell growth induced by neuronal excitation in both the central and peripheral nervous systems. Aberrant expression of somatostatin receptors is known in a large number of human tumors. SSTR1 has been reported at highest levels in the jejunum and stomach. In addition, this receptor is expressed in adrenal, brain, liver, lung, eye, and pancreas. Selective activation of SSTR1 inhibits hormone secretion and cell viability in GH-secreting and PRL-secreting adenomas in vitro.

SSTR2 is expressed in highest levels in the stomach, jejunum, cerebrum, thyroid and kidney. Its gene expression is lost in 90% of human pancreatic adenocarcinomas while SSTR2 expression in neuroblastoma correlates positively to overall and event-free survival. Expression of SSTR-2 and SSTR-5 may be important in the growth inhibitory effect of somatostatin in human pancreatic cancer.

SSTR3 mRNA is detected in the brain and pancreatic islets. Aberrant expression of somatostatin receptors is known in a large number of human tumors.

SSTR4 is highly expressed in human brain, lungs, gastrointestinal tract, pancreas and prostates. It inhibits the release of many hormones and other secretory proteins.

SSTR5 is expressed in adult pituitary gland, heart, small intestine, adrenal gland, cerebellum and fetal hypothalamus. SSTR5 is a candidate gene for bipolar affective disorder as well as for other neuropsychiatric disorders. Expression of SSTR5 may be important in the growth inhibitory effect of somatostatin in human pancreatic cancer.

Somatostatin Cell Lines

Receptor Family	Receptor	Species	Parental	Stable Cell Lines	Division-Arrested Cells	Membranes
Somatostatin	sst1	human	CHO-K1	C1345-1a	DC1345-1a	MC1345-1a
	sst1	human	CHO-K1 Gα16	CG1345-1	DCG1345-1	MCG1345-1
	sst2	human	CHO-K1	C1346-1	DC1346-1	MC1346-1
	sst2	human	CHO-K1 Gα16	CG1346-1	DCG1346-1	MCG1346-1
	sst3	human	CHO-K1	C1347-1	DC1347-1	MC1347-1
	sst3	human	CHO-K1 Gα16	CG1347-1	DCG1347-1	MCG1347-1
	sst4	human	CHO-K1	C1348-1a	DC1348-1a	MC1348-1a
	sst4	human	CHO-K1 Gα16	CG1348-1	DCG1348-1	MCG1348-1
	sst5	human	CHO-K1	C1349-1	DC1349-1	MC1349-1
	sst5	human	CHO-K1 Gα16	CG1349-1	DCG1349-1	MCG1349-1