The aurora kinase A regulates GSK-3beta in gastric cancer cells

Oncogene. 2009 Feb 12;28(6):866-75. doi: 10.1038/onc.2008.434. Epub 2008 Dec 8.

Abstract

Aurora kinase A (AURKA) is located at 20q13, a region that is frequently amplified in gastric cancer. In this study, we have investigated the role of AURKA in regulating glycogen synthase kinase (GSK)-3beta and beta-catenin/TCF complex in gastric cancer cells. Our results demonstrate a significant increase in the phosphorylation of GSK-3beta at Ser 9 following the overexpression of AURKA in AGS cells. The immunoprecipitation with antibodies specific for AURKA and GSK-3beta indicated that the two proteins coexist in the same protein complex. The recombinant human AURKA protein phosphorylated the GSK-3beta protein at Ser 9 in a concentration-dependent manner, in vitro. The phosphorylation of beta-catenin (Ser33/37/Thr41) by GSK-3beta is known to target beta-catenin towards degradation. In line with our findings, the increase in phospho-GSK-3beta level was accompanied by a significant decrease in beta-catenin phosphorylation (Ser33/37/Thr41) and accumulation of beta-catenin protein. The knockdown of AURKA reversed the phosphorylation of GSK-3beta and the beta-catenin protein levels. The immunofluorescence analysis demonstrated colocalization of AURKA and GSK-3beta proteins and a significant increase in the nuclear beta-catenin levels in cells overexpressing AURKA. The beta-catenin/TCF transcription activity was measured using the pTopFlash and its mutant pFopFlash luciferase reporter vectors. Indeed, AURKA overexpression led to a significant increase in the pTopFlash reporter activity, whereas kinase dead AURKA mutant (D274A) had no effect. Consistent with these findings, we detected a significant mRNA up-regulation of several direct targets of the beta-catenin/TCF transcription complex (cyclin D1, c-MYC, c-MYC-binding protein, CLDN1, FGF18 and vascular endothelial growth factor), and a two-fold increase in the proliferation rate in AURKA overexpressing cells. We conclude that the AURKA/GSK-3beta interaction is important in regulating beta-catenin, underscoring a novel oncogenic potential for AURKA in gastric tumorigenesis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Active Transport, Cell Nucleus
  • Aurora Kinase A
  • Aurora Kinases
  • Cell Line, Tumor
  • Cell Separation
  • Flow Cytometry
  • Gene Expression Regulation, Neoplastic*
  • Glycogen Synthase Kinase 3 / metabolism*
  • Glycogen Synthase Kinase 3 beta
  • Humans
  • Microscopy, Fluorescence / methods
  • Models, Biological
  • Phosphorylation
  • Protein-Serine-Threonine Kinases / metabolism*
  • RNA, Small Interfering / metabolism
  • Recombinant Proteins / chemistry
  • Stomach Neoplasms / enzymology
  • Stomach Neoplasms / metabolism*
  • beta Catenin / metabolism

Substances

  • RNA, Small Interfering
  • Recombinant Proteins
  • beta Catenin
  • AURKA protein, human
  • Aurora Kinase A
  • Aurora Kinases
  • GSK3B protein, human
  • Glycogen Synthase Kinase 3 beta
  • Protein-Serine-Threonine Kinases
  • Glycogen Synthase Kinase 3