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

ABSTRACT 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 10 pmol/L‐10 nmol/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.