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

Abstract

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.

Rapid protein kinase D1 signaling promotes migration of intestinal epithelial cells

“…Consistent with the results presented here, PKD1 has been also implicated in the motility of fibroblasts (34,61), endothelial cells (11), and prostate cancer cells (22,63) and invasion of pancreatic cancer cells (30). However, other studies concluded that PKD1 inhibits the motility of other cell lines, including HeLa and breast cancer cell lines (10,32).…”

Positive cross talk between protein kinase D and β-catenin in intestinal epithelial cells: impact on β-catenin nuclear localization and phosphorylation at Ser552

“…New recurrent PRKD1 gene rearrangements and variant fusions have been found in cribriform adenocarcinoma of the oropharynx (71). PKD1 has been proposed as a therapeutic target in pancreatic (15,31,37) and colon (69) cancers, although a different conclusion has also been presented (57). It is conceivable that the PKD/␤-catenin cross talk identified here contributes to the mechanism(s) by which PKDs promote malignant transformation of epithelial cells, but further systematic studies are needed to prove this hypothesis.…”

Protein Kinase D1 Mediates Anchorage-dependent and -independent Growth of Tumor Cells via the Zinc Finger Transcription Factor Snail1

“…However, specific and detailed functions for distinct PKD isoforms have not been addressed so far. In a previous work, Ochi et al (38) have proposed a function for PKD1 in the regulation of anchorage-dependent growth. However, the properties of distinct PKD isoforms were not directly compared or addressed by inhibitors that are not isoform-specific.…”