Combined effects of EGFR and Hedgehog signaling pathway inhibition on the proliferation and apoptosis of pancreatic cancer cells.

In the present study, we established a new experimental model to investigate the effects of EGFR targeting by RNAi, and the synergistic actions between the hedgehog (Hh) and EGFR signaling pathways on the proliferation and apoptosis in pancreatic cancer cells. Three human pancreatic cancer cell lines expressing EGFR shRNA were established, and gene expression inhibition was assessed in these lines using RT-PCR and western blot analysis. The effects of EGFR RNAi and Hh inhibition on cell proliferation and apoptosis were explored in vitro and in vivo. We observed that EGFR RNAi notably inhibited cell proliferation and colony formation, induced apoptosis and markedly decreased xenograft tumor growth. Furthermore, EGFR RNAi significantly enhanced cyclopamine sensitivity both in vitro and in vivo, and a synergistic decrease of both AKT and ERK phosphorylation was observed. The present study demonstrates that combined inhibition of both EGFR and Hh signaling pathways could establish a more promising antitumor approach than inhibiting each singly, and that there is a possible synergistic effect for Hh and EGFR signaling pathways on ERK and AKT phosphorylation.