Human pancreatic cancer cells express a functional autocrine growth loop requiring the EGF receptor and map kinase

Several potential aulocrine growth pathways have been detected in human pancreatic cancer cells. However, no clear evidence exists to show if endogenous growth factors produced from pancreatic cancer ceils directly stimulates cell proliferation in an autocrine fashion. This study investigated whether or not functional autocrine growth pathways are expressed in different pancreatic cancer cells lines (HPAF and CAPAN-2) and if the EGF receptor (EGFR) is required for the autocrine effect. HPAF (weaned from serum dependence to amplify autocrine processes) and CAPAN-2 cells were seeded in 24-well plates (35,000/well). After 3 days, fresh serum-free media was added. Control cells continued to receive fresh media every 12 hours (to prevent build up of endogenous growth factors) and stimulated cells received no change of media for 4 days. Cells were also exposed to an EGFR-specific tyrosine kinase inhibitor (AGI478. lOuM) and an inhibitor of MAP kinase activation (PD98059, 20u,M). Proliferation was measured using [3H]-thymidine incorporation into DNA. Data is expressed as % of control. Stimulation AC 1478 PD98059 (All data HPAF(n-6) 117±28 -49i5 5±15 significant. CAPAN-2 (n=5) 137±32 -7i 7 -27±8 p0.001) A FGFa neutralizing antibody had no significant effect on endogenous stimulation whereas heparin caused a 70% inhibition (p<0.001). This study clearly shows an active autocrine loop in human pancreatic cancer cells which employs the EGFR and MAP kinase. Amphiregulin or heparin binding-EG!; mav he Ihe endogenous hy.ind that activates the EGFR.