Activated PAR-2 regulates pancreatic cancer progression through ILK/HIF-α-induced TGF-α expression and MEK/VEGF-A-mediated angiogenesis

Am J Pathol. 2013 Aug;183(2):566-75. doi: 10.1016/j.ajpath.2013.04.022. Epub 2013 Jun 10.


Tissue factor initiates the process of thrombosis and activates cell signaling through protease-activated receptor-2 (PAR-2). The aim of this study was to investigate the pathological role of PAR-2 signaling in pancreatic cancer. We first demonstrated that activated PAR-2 up-regulated the protein expression of both hypoxia-inducible factor-1α (HIF-1α) and HIF-2α, resulting in enhanced transcription of transforming growth factor-α (TGF-α). Down-regulation of HIFs-α by siRNA or YC-1, an HIF inhibitor, resulted in depleted levels of TGF-α protein. Furthermore, PAR-2, through integrin-linked kinase (ILK) signaling, including the p-AKT, promoted HIF protein expression. Diminishing ILK by siRNA decreased the levels of PAR-2-induced p-AKT, HIFs-α, and TGF-α; our results suggest that ILK is involved in the PAR-2-mediated TGF-α via an HIF-α-dependent pathway. Furthermore, the culture medium from PAR-2-treated pancreatic cancer cells enhanced human umbilical vein endothelial cell proliferation and tube formation, which was blocked by the MEK inhibitor, PD98059. We also found that activated PAR-2 enhanced tumor angiogenesis through the release of vascular endothelial growth factor-A (VEGF-A) from cancer cells, independent of the ILK/HIFs-α pathways. Consistent with microarray analysis, activated PAR-2 induced TGF-A and VEGF-A gene expression. In conclusion, the activation of PAR-2 signaling induced human pancreatic cancer progression through the induction of TGF-α expression by ILK/HIFs-α, as well as through MEK/VEGF-A-mediated angiogenesis, and it plays a role in the interaction between cancer progression and cancer-related thrombosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Basic Helix-Loop-Helix Transcription Factors / physiology
  • Cell Line, Tumor
  • Down-Regulation
  • Flavonoids / pharmacology
  • Humans
  • Hypoxia-Inducible Factor 1, alpha Subunit / antagonists & inhibitors
  • Hypoxia-Inducible Factor 1, alpha Subunit / physiology
  • Indazoles / pharmacology
  • Mitogen-Activated Protein Kinase Kinases / antagonists & inhibitors
  • Mitogen-Activated Protein Kinase Kinases / physiology*
  • Neovascularization, Pathologic / enzymology
  • Neovascularization, Pathologic / etiology
  • Pancreatic Neoplasms / blood supply
  • Pancreatic Neoplasms / enzymology
  • Protein Kinase Inhibitors / pharmacology
  • Protein-Serine-Threonine Kinases / physiology*
  • RNA, Small Interfering / physiology
  • Receptor, PAR-2 / physiology*
  • Signal Transduction / physiology
  • Transforming Growth Factor alpha / metabolism*
  • Up-Regulation
  • Vascular Endothelial Growth Factor A / physiology*


  • Basic Helix-Loop-Helix Transcription Factors
  • Flavonoids
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Indazoles
  • Protein Kinase Inhibitors
  • RNA, Small Interfering
  • Receptor, PAR-2
  • Transforming Growth Factor alpha
  • Vascular Endothelial Growth Factor A
  • 3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole
  • endothelial PAS domain-containing protein 1
  • integrin-linked kinase
  • Protein-Serine-Threonine Kinases
  • Mitogen-Activated Protein Kinase Kinases
  • 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one