Modulation of cellular migration and survival by c-Myc through the downregulation of urokinase (uPA) and uPA receptor

Mol Cell Biol. 2010 Apr;30(7):1838-51. doi: 10.1128/MCB.01442-09. Epub 2010 Feb 1.

Abstract

It has been proposed that c-Myc proapoptotic activity accounts for most of its restraint of tumor formation. We established a telomerase-immortalized human epithelial cell line expressing an activatable c-Myc protein. We found that c-Myc activation induces, in addition to increased sensitivity to apoptosis, reductions in cell motility and invasiveness. Transcriptome analysis revealed that urokinase (uPA) and uPA receptor (uPAR) were strongly downregulated by c-Myc. Evidence is provided that the repression of uPA and uPAR may account for most of the antimigratory and proapoptotic activities of c-Myc. c-Myc is known to cooperate with Ras in cellular transformation. We therefore investigated if this cooperation could converge in the control of uPA/uPAR expression. We found that Ras is able to block the effects of c-Myc activation on apoptosis and cellular motility but not on cell invasiveness. Accordingly, the activation of c-Myc in the context of Ras expression had only minor influence on uPAR expression but still had a profound repressive effect on uPA expression. Thus, the differential regulation of uPA and uPAR by c-Myc and Ras correlates with the effects of these two oncoproteins on cell motility, invasiveness, and survival. In conclusion, we have discovered a novel link between c-Myc and uPA/uPAR. We propose that reductions of cell motility and invasiveness could contribute to the inhibition of tumorigenesis by c-Myc and that the regulation of uPA and uPAR expression may be a component of the ability of c-Myc to reduce motility and invasiveness.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / physiology
  • Cell Line
  • Cell Movement / physiology*
  • Cell Survival / physiology*
  • Chemokines / metabolism
  • Culture Media, Conditioned / metabolism
  • Cyclin-Dependent Kinase Inhibitor p21 / genetics
  • Cyclin-Dependent Kinase Inhibitor p21 / metabolism
  • Down-Regulation
  • Enzyme Activation
  • Epithelial Cells / cytology
  • Epithelial Cells / physiology
  • Gene Silencing
  • Humans
  • Kruppel-Like Transcription Factors / genetics
  • Kruppel-Like Transcription Factors / metabolism
  • Proto-Oncogene Proteins c-myc / genetics
  • Proto-Oncogene Proteins c-myc / metabolism*
  • Receptors, Urokinase Plasminogen Activator / genetics
  • Receptors, Urokinase Plasminogen Activator / metabolism*
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism
  • Urokinase-Type Plasminogen Activator / genetics
  • Urokinase-Type Plasminogen Activator / metabolism*
  • ras Proteins / genetics
  • ras Proteins / metabolism

Substances

  • Chemokines
  • Culture Media, Conditioned
  • Cyclin-Dependent Kinase Inhibitor p21
  • Kruppel-Like Transcription Factors
  • Proto-Oncogene Proteins c-myc
  • Receptors, Urokinase Plasminogen Activator
  • Tumor Suppressor Protein p53
  • ZBTB17 protein, human
  • Urokinase-Type Plasminogen Activator
  • ras Proteins