A Human Gastric Cancer Cell Line Possesses a Functional Receptor for Gastrin-Releasing Peptide

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Abstract
Bombesin (BBS) exhibits diverse biological functions including those of neurotransmitter, regulator of gastrointestinal hormone release, and mitogen. Gastrin-releasing peptide (GRP, the mammalian equivalent of BBS) is found in mucosal cells of the gastric fundus and antrum. We determined whether a human gastric cancer cell line (SHA) expresses a functional GRP-receptor (GRP-R). BBS increased intracellular calcium ([Cd2+]i), and a specific GRP-R antagonist, ([D-Phe6. Des-Met14]-BBS (6-14)-ethylamide), blocked BBS-induced increase in [Ca2+]i,- SHA cells possess GRP-R mRNA by reverse transcriptase-PCR. Furthermore, these cells possess an 80-kDa cell surface protein that specifically binds BBS with two high-binding affinities (Kd1 = 0.6 nM, Kd2 = 6.7 nM). These findings indicate that SHA cells possess a GRP-R that is capable of physiological signal transduction, though the cellular response remains unknown.