Protein kinase D1 promotes anchorage-independent growth, invasion, and angiogenesis by human pancreatic cancer cells

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal diseases. Novel molecularly targeted therapies are urgently needed. Here, we extended our studies on the role of protein kinase D1 (PKD1) in PDAC cell lines. Given that Panc-1 express moderate levels of PKD1, we used retroviral-mediated gene transfer to create a Panc-1 derivative that stably over-expresses PKD1 (Panc-1-PKD1). Reciprocally, we used shRNA targeting PKD1 in Panc-28 to produce a PKD1 under-expressing Panc-28 derivative (Panc-28-shPKD1). Our results demonstrate that Panc-1-PKD1 cells exhibit significantly increased anchorage-independent growth in soft agar and increased in vitro invasion compared with Panc-1-mock. Reciprocally, Panc-28-shPKD1 cells show a significant decrease in anchorage-independent growth and invasiveness, as compared with Panc-28-mock cells. The selective PKD family inhibitor CRT0066101 markedly decreased colony-forming ability and invasiveness by either Panc-1-PKD1 or Panc-28-mock cells. Secretion of the pro-angiogenic factors vascular endothelial growth factor (VEGF) and CXC chemokines (CXCL8) was significantly elevated by PKD1 over-expression in Panc-1 cells and reduced either by depletion of PKD1 via shRNA in Panc-28 cells or by addition of CRT0066101 to either Panc-1-PKD1 or Panc-28-mock cells. Furthermore, human umbilical vein endothelial cell (HUVEC) tube formation was significantly enhanced by co-culture with Panc-1-PKD1 compared with Panc-1-mock in an angiogenesis assay in vitro. Conversely, PKD1 depletion in Panc-28 cells decreased their ability to induce endotube formation by HUVECs. PDAC-induced angiogenesis in vitro and in vivo was markedly inhibited by CRT0066101. Our results lend further support to the hypothesis that PKD family members provide a novel target for PDAC therapy.