Several studies have reported effects of gastrointestinal regulatory peptides on growth of experimentally induced pancreatic neoplasms and human cancer cell lines. The growth of human pancreatic cancer lines PANC-1 and MIA PaCa-2 was characterized in vitro, and the effects of cholecystokinin, bombesin, insulin, epidermal growth factor, secretin, vasoactive intestinal peptide, and somatostatin were determined. Fetal bovine serum was required for initiation of growth in both cell lines. Growth effects of peptides were determined by incubating cells with peptides in serum-free medium after a 72-h preincubation in 10% serum-supplemented medium alone. Epidermal growth factor (3.4 x 10(-9) M) and insulin (10(-6) M) significantly (p less than 0.001) increased growth of both cell lines as determined by increases in deoxyribonucleic acid and protein. Bombesin, secretin, vasoactive intestinal peptide, and somatostatin (all 10(-8) M) did not affect growth of either cell line. Neither cholecystokinin-8 nor [Thr4, Nle7] cholecystokinin-9 altered growth in concentrations from 10(-12)-10(-6) M. Anchorage-dependent clonogenic growth of both cell lines was also not altered by cholecystokinin-8. Cholecystokinin added to cultures was degraded by separate effects of serum and cells. Addition of cholecystokinin-8 to cultures every 8 h maintained cholecystokinin levels but did not alter cell growth. These data support roles for epidermal growth factor and insulin as growth factors for human pancreatic cancer cell lines.