PAK5-mediated E47 phosphorylation promotes epithelial-mesenchymal transition and metastasis of colon cancer

Oncogene. 2016 Apr 14;35(15):1943-54. doi: 10.1038/onc.2015.259. Epub 2015 Jul 27.

Abstract

The p21-activated kinase 5 (PAK5) is overexpressed in advanced cancer and the transcription factor E47 is a direct repressor of E-cadherin and inducer of epithelial-mesenchymal transition (EMT). However, the relationship between PAK5 and E47 has not been explored. In this study, we found that PAK5-mediated E47 phosphorylation promoted EMT in advanced colon cancer. PAK5 interacted with E47 and phosphorylated E47 on Ser39 under hepatocyte growth factor (HGF) stimulation, which decreased cell-cell cohesion, increased cell migration and invasion in vitro and promoted metastasis in a xenograft model. Furthermore, phosphorylation of E47 facilitated its accumulating in nucleus in an importin α-dependent manner, and enhanced E47 binding to E-cadherin promoter directly, leading to inhibition of E-cadherin transcription. In contrast, PAK5-knockdown resulted in blockage of HGF-induced E47 phosphorylation, attenuated association of E47 with importin α and decreased E47 binding to E-cadherin promoter. In addition, we demonstrated a close correlation between PAK5 and phospho-Ser39 E47 expression in colon cancer specimens. More importantly, high expression of phospho-E47 was associated with an aggressive phenotype of colon cancer and nuclear phospho-E47 staining was found in certain cases of colon cancer with metastasis. Collectively, E47 is a novel substrate of PAK5, and PAK5-mediated phosphorylation of E47 promotes EMT and metastasis of colon cancer, suggesting that phosphorylated E47 on Ser39 may be a potential therapeutic target in progressive colon cancer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Active Transport, Cell Nucleus
  • Animals
  • Cadherins / metabolism
  • Cell Adhesion
  • Cell Line, Tumor
  • Cell Movement
  • Chromones / pharmacology
  • Colonic Neoplasms / metabolism
  • Colonic Neoplasms / pathology*
  • Epithelial-Mesenchymal Transition*
  • Female
  • Gene Expression Regulation, Neoplastic
  • Genes, Reporter
  • Hepatocyte Growth Factor / pharmacology
  • Humans
  • Liver Neoplasms / secondary
  • Mice
  • Mice, Nude
  • Morpholines / pharmacology
  • Neoplasm Invasiveness
  • Neoplasm Metastasis / genetics*
  • Neoplasm Proteins / antagonists & inhibitors
  • Neoplasm Proteins / metabolism*
  • Phenotype
  • Phosphorylation
  • Phosphoserine / metabolism
  • Protein Binding
  • Protein Interaction Mapping
  • Protein Kinase Inhibitors / pharmacology
  • Protein Processing, Post-Translational*
  • Transcription Factor 3 / metabolism*
  • Transcription, Genetic
  • alpha Karyopherins / metabolism
  • p21-Activated Kinases / antagonists & inhibitors
  • p21-Activated Kinases / metabolism*

Substances

  • Cadherins
  • Chromones
  • KPNA1 protein, human
  • Morpholines
  • Neoplasm Proteins
  • Protein Kinase Inhibitors
  • Transcription Factor 3
  • alpha Karyopherins
  • Phosphoserine
  • 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
  • Hepatocyte Growth Factor
  • PAK5 protein, human
  • p21-Activated Kinases