Antiproliferative effect of somatostatin and analogs.

Over the past decade, antiproliferative effects of somatostatin and analogs have been reported in many somatostatin receptor-positive normal and tumor cell types. Regarding the molecular mechanisms involved, somatostatin or analogs mediate their action through both indirect and direct effects. Somatostatin acts through five somatostatin receptors (SSTR1-5) which are variably expressed in normal and tumor cells. These receptors regulate a variety of signal transduction pathways including inhibition of adenylate cyclase, regulation of ion channels, regulation of serine/threonine and tyrosine kinases and phosphatases. This review focuses on recent advances in biological mechanisms involved in the antineoplastic activity of somatostatin and analogs.