Inhibition of Human Epithelial Ovarian Cancer Cell Growth in vitro by Somatostatin Analog RC-160

In this study, we investigated the effects of somatostatin analog RC-160 on the growth of the OV-1063 human epithelial ovarian cancer cell line in vitro. RC-160 inhibited cell proliferation, as measured by cell number, and [³H]thymidine incorporation into DNA at 10^–9–10^–5<i>M</i>. In OV-1063 cells, ¹²⁵I-labeled RC-160 was bound to one class of specific, saturable binding sites with high affinity (K_d = 0.2 ± 0.03 n<i>M</i>) and low capacity (5,500 binding sites per cell). ¹²⁵I-labeled RC-160 could be displaced by unlabeled RC-160. Ligand binding was dependent on time and temperature. Receptor internalization assay showed that the ligand-receptor complex was internalized at 37°C, which indicates the presence of biologically active somatostatin receptors on OV-1063 cells. These results suggest that somatostatin analog RC-160 can suppress the growth of OV-1063 human epithelial ovarian cancer cells by a direct action and that the inhibitory effect of somatostatin analog is mediated through the high-affinity somatostatin receptors.