Expression of progastrin-derived peptides and gastrin receptors in a panel of gastrointestinal carcinoma cell lines.

To assess the potential of gastrin receptor antagonists in the treatment of gastrointestinal cancer, the presence of an autocrine loop involving progastrin-derived peptides has been investigated in two colorectal and one gastric carcinoma cell lines. Progastrin, glycine-extended gastrin and amidated gastrin were detected in cell extracts or conditioned media by radio-immunoassay. Low-affinity binding sites for glycine-extended gastrin and amidated gastrin were present, but high-affinity binding sites were not detected with the appropriate iodinated ligands. In addition, neither glycine-extended gastrin nor amidated gastrin in the concentration range 10pmol/L-10nmol/L stimulated cell proliferation. We conclude that it is unlikely that the carcinoma cell lines LIM 1215, LIM 1839 and LIM 1899 use either amidated or glycine-extended gastrins as extracellular autocrine growth factors.