AbstractThe role of gastrin in the control of growth of renal G401 cells isolated from a human nephroblastoma (Wilms' tumour) was investigated. G401 cell growth was enhanced in the presence of exogenous gastrin. Addition of anti‐gastrin antibodies to serum‐free medium significantly inhibited the growth of G401 cells. G401 cells contained the equivalent of 4.3 pg/106cells of gastrin, and serum‐free medium collected over 48 hr from G401 cells contained the equivalent of 38 ng/106cells of gastrin, as determined by radioimmunoassay. Growth of G401 cells was inhibited in a concentration‐related way by a variety of gastrin/CCK receptor antagonists. Devazepide and proglumide were, respectively, the most and the least potent inhibitors of G401 cell growth (potency order devazepide>L‐365,260 = lorglumide>loxiglumide>benzotript>proglumide). These gastrin/CCK receptor antagonists had similar growth‐inhibitory activities in human colonic adenocarcinoma HCT‐116 cells. Growth of HCT‐116 cells was stimulated to a lesser extent, as compared with G401 cells, by exogenous gastrin, and endogenous gastrin was not detectable in HCT‐116 cells. The results are consistent with a role for a gastrin‐like peptide in the control of growth of a renal cell line. The data suggest that gastrin/CCK receptor antagonists warrant further investigation as therapeutic agents for the control of gastrin‐responsive tumours derived from outside, as well as inside, the gastrointestinal tract, including tumours derived from the kidney.