PTTG induces EMT through integrin αVβ3-focal adhesion kinase signaling in lung cancer cells

Oncogene. 2012 Jun 28;31(26):3124-35. doi: 10.1038/onc.2011.488. Epub 2011 Nov 14.

Abstract

Pituitary tumor transforming gene (PTTG) is a well-studied oncogene for its role in tumorigenesis and serves as a marker of malignancy in several cancer types including lung. In the present study, we defined the role of PTTG in actin cytoskeleton remodeling, cell migration and induction of epithelial mesenchymal transition (EMT) through the regulation of integrin α(V)β(3)-FAK (focal adhesion kinase) signaling pathway. Overexpression of PTTG through an adenovirus vector resulted in a significant increase in the expression of integrins α(V) and β(3), a process that was reversed with the downregulation of PTTG expression through the use of an adenovirus expressing PTTG-specific small interfering RNA (siRNA). Western blot analysis of cells infected with adenovirus PTTG cDNA resulted in increased FAK and enhanced expression of adhesion complex molecules paxillin, metavincullin, and talin. Furthermore, downstream signaling genes Rac1, RhoA, Cdc42 and DOCK180 showed upregulation upon PTTG overexpression. This process was dependent on integrin α(V), as blockage by antagonist echistatin (RGD peptide) or α(V)-specific siRNA resulted in a decrease in FAK and subsequent adhesion molecules. Actin cytoskeleton disruption was detected as a result of integrin-FAK signaling by PTTG as well as enhanced cell motility. Taken together, our results suggest for the first time an important role of PTTG in regulation of integrins α(V) and β(3) and adhesion-complex proteins leading to induction of EMT.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Actin Cytoskeleton / drug effects
  • Actin Cytoskeleton / metabolism
  • Actin Cytoskeleton / pathology
  • Biomarkers, Tumor / genetics
  • Cadherins / genetics
  • Cell Line, Tumor
  • Cell Movement / drug effects
  • Epithelial-Mesenchymal Transition* / drug effects
  • Focal Adhesion Protein-Tyrosine Kinases / metabolism*
  • Gene Expression Regulation, Neoplastic / drug effects
  • Gene Knockdown Techniques
  • Humans
  • Integrin alphaVbeta3 / antagonists & inhibitors
  • Integrin alphaVbeta3 / deficiency
  • Integrin alphaVbeta3 / genetics
  • Integrin alphaVbeta3 / metabolism*
  • Lung Neoplasms / enzymology
  • Lung Neoplasms / metabolism*
  • Lung Neoplasms / pathology*
  • Neoplasm Proteins / metabolism*
  • Oligopeptides / pharmacology
  • Phosphorylation / drug effects
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • RNA, Small Interfering / genetics
  • Securin
  • Signal Transduction* / drug effects
  • Vimentin / genetics

Substances

  • Biomarkers, Tumor
  • Cadherins
  • Integrin alphaVbeta3
  • Neoplasm Proteins
  • Oligopeptides
  • RNA, Messenger
  • RNA, Small Interfering
  • Securin
  • Vimentin
  • pituitary tumor-transforming protein 1, human
  • arginyl-glycyl-aspartic acid
  • Focal Adhesion Protein-Tyrosine Kinases