Somatostatin inhibits rapid centrosomal separation and cell proliferation induced by epidermal growth factor.

The role of endogenous growth inhibitors in the regulation of cell proliferation is unclear. Although there are numerous studies on the stimulatory effect of peptide hormones such as insulin, the somatomedins and epidermal growth factor (EGF) on cell proliferation, little is known about the existence of hormones that might exert an antiproliferative effect on cells. Somatostatin (SS), a cyclic tetradecapeptide hormone that is widely distributed in the body, exerts an inhibitory effect on numerous cellular processes. We observed that SS at concentrations of 10(-8) - 10(13M), inhibited EGF-induced centrosomal separation, which recent evidence suggests is necessary for DNA synthesis in response to EGF. This SS effect was associated with inhibition of DNA synthesis and cell replication induced by EGF in gerbil fibroma and HeLa cells. Inhibition of centrosomal separation and the consequent antiproliferative effect of SS may represent a biologically significant action of this ubiquitous hormone.