Stimulation of DNA Synthesis in Pancreatic Duct Cells by Gastrointestinal Hormones

Pancreatic duct cells of the Syrian hamster were grown as monolayers on thin layers of type I collagen coated onto microporous membranes. The effects of a number of potential trophic factors were tested by their ability to increase [3H]thymidine incorporation into cellular DNA. To measure the effect of growth factors, cells were subjected to a period of growth factor depletion to induce a state of partial quiescence in DNA synthesis. Cells responded with a significant increase in thymidine incorporation after the addition of epidermal growth factor (EGF) alone or a growth factor mixture containing EGF plus insulin, transferrin, selenium, linoleic acid, bovine pituitary extract, triiodothyronine, and dexamethasone. When the serum substitute, Nu Serum IV (5%, vol/vol), was added to this mixture, addition of several gastrointestinal (GI) hormones including secretin, vasoactive intestinal polypeptide (VIP), bombesin, and gastrin caused significant increases in thymidine incorporation at concentrations of 0.01-1 microM. At 1 microM, these hormones stimulated DNA synthesis relative to their respective control in the order secretin (178%) greater than bombesin (153%) greater than VIP (138%) greater than gastrin (126%). Cholecystokinin octapeptide, a known trophic factor for pancreatic acinar cells, did not cause significant increases in thymidine incorporation in cultured duct cells. These results suggest that pancreatic duct cells possess receptors for a number of GI hormones and respond to the trophic effects of hormones known to stimulate pancreatic growth in vivo.