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CCK antagonists interact with CCK-B receptors on human small cell lung cancer cells
J Staley1, R T Jensen, T W Moody
1Department of Biochemistry and Molecular Biology, George Washington University School of Medicine and Health Sciences, Washington, DC 20037.
Abstract:
The ability of cholecystokinin (CCK) receptor antagonists to interact with CCK receptors in small cell lung cancer (SCLC) cells was investigated. L-365,260, CCK-8, L-364,718, CBZ-CCK(27-32)-NH2 and proglumide analogue 10 inhibited specific 125I-CCK-8 binding to SCLC cells with IC50 values of 0.2, 2, 500, 100,000 and 500,000 nM, respectively. Gastrin-I and CCK-8 elevated the cytosolic Ca2+ when SCLC cells were loaded with Fura 2-AM. L-365,260 inhibited the cytosolic Ca2+ increase caused by 10 nM CCK-8 in a dose-dependent manner. The effects of 10 nM L-365,260 were reversed by high concentrations of CCK-8. These data indicate that L-365,260 functions as a reversible CCK-8 antagonist using SCLC cells.