Gastrin-Enhanced Tumor Growth of a Xenotransplantable Human Gastric Carcinoma in Nude Mice

Abstract

A human tumor line serially transplantable in nude mice, originating from a well-differentiated papillo-tubular adenocarcinoma of the stomach, was established. The growth of this tumor was enhanced by daily injection of C-terminal tetrapeptide gastrin into the mice. Although there was little difference in histology, the gastrin-stimulated tumor had larger glandular spaces filled with mucin-like substance than the control tumor. 3H-thymidine uptake of the gastrin stimulated tumor was higher than that of control, as shown by microradiography and counting of radioactivity in tissue homogenates. The plasma membrane fraction of the tumor revealed positive binding for gastrin and the cytosol fraction contained cyclic AMP dependent- and independent protein kinases. Incubation of tumor slices with gastrin caused a conformational change in the enzymes. Therefore we conclude that this G4 tumor line xenotransplantable in nude mice is sensitive to gastrin in its trophic and secretory mechanisms.