DISSOCIATED SECRETION OF ISLET AMYLOID POLYPEPTIDE AND INSULIN IN SERUM-FREE CULTURE MEDIA CONDITIONED BY HUMAN PANCREATIC ADENOCARCINOMA CELL-LINES

Conclusion. The cosecretion of insulin and islet amyloid polypeptide ( IAPP) is altered when isolated rat pancreatic islets are incubated in culture media conditioned by human pancreatic cancer cells. Background . Pancreatic cancer is usually associated with impaired glucose tolera nce. This study investigates the tumor-derived influence on beta-cell secretion of pancreatic islets. Methods. Four conditioned media were p repared from two human pancreatic cancer cell lines (Pane-1 and HPAF), a hamster pancreatic cancer cell line (PC-1), and a fibroblast cell l ine (Ag 1523). Isolated rat pancreatic islets were incubated first in the conditioned media or nonconditioned control medium for 24 h, then in the same kind of media containing 100 mu M carbamylcholine for 90 m in. Insulin and IAPP secretion were measured by radioimmunoassay. Resu lts. Islets in media conditioned by Pane-1 and HPAF cells demonstrated dissociation of insulin and IAPP secretion. During 24-h incubation, t he dissociation was expressed as selectively decreased insulin secreti on. With addition of 100 mu M carbamylcholine, the dissociation was ex pressed as normal secretion of insulin and hypersecretion of IAPP. As a result, the IAPP/insulin molar ratios were increased in both groups during both time periods. The islets in PC-1 and Ag 1523 media did not show any significant changes in insulin and IAPP secretion.