Somatostatin and cancer: applying endocrinology to oncology.

Somatostatin is a peptide hormone that normally suppresses growth hormone (GH), thyrotropin (TSH), insulin and gut hormone release, as well as affecting multiple aspects of gastrointestinal function. It achieves these pleiotropic effects by binding somatostatin receptors (SSTR), a family of five G-protein coupled membrane receptors. Somatostatin analogs, such as octreotide, lanreotide and vapreotide, are well-established treatments for tumors that over secrete these hormones. Recently, use of somatostatin analogs for treating nonendocrine malignancies are being explored. Hu et al. found progressive reduction in SSTR3 expression when comparing normal gastric mucosa versus well differentiated versus poorly differentiated gastric adenocarcinomas; octreotide inhibited growth and induced apoptosis in vitro of those cells expressing SSTR3. Potential mechanisms by which somatostatin analogs may be useful in oncology include its endocrine actions, autocrine/paracrine effects, SSTR-mediated cell signaling and SSTR-mediated cell labeling.