At diagnosis, the majority of
pancreatic cancer patients present with advanced disease when curative resection is no longer feasible and current therapeutic treatments are largely ineffective. An improved understanding of molecular targets for effective intervention of
pancreatic cancer is thus urgent. The
Met receptor tyrosine kinase is one candidate implicated in
pancreatic cancer. Notably, Met is over expressed in up to 80% of invasive
pancreatic cancers but not in normal ductal cells correlating with poor overall patient survival and increased recurrence rates following surgical resection. However the functional role of Met signaling in
pancreatic cancer remains poorly understood. Here we used RNA interference to directly examine the pathobiological importance of increased Met signaling for
pancreatic cancer. We show that Met knockdown in pancreatic
tumor cells results in decreased cell survival, cell invasion, and migration on
collagen I in vitro. Using an orthotopic model for
pancreatic cancer, we provide in vivo evidence that Met knockdown reduced
tumor burden correlating with decreased cell survival and
tumor angiogenesis, with minimal effect on cell growth. Notably, we report that Met signaling regulates the secretion of the pro-angiogenic
chemokine interleukin-8/CXCL8. Our data showing that the
interleukin-8 receptors CXCR1 and CXCR2 are not expressed on pancreatic
tumor cells, suggests a paracrine mechanism by which Met signaling regulates
interleukin-8 secretion to remodel the tumor microenvironment, a novel finding that could have important clinical implications for improving the effectiveness of treatments for
pancreatic cancer.