Down-regulation of uPAR and cathepsin B retards cofilin dephosphorylation

Int J Oncol. 2006 Mar;28(3):633-9.

Abstract

Cathepsin B and uPAR play key roles in cancer cell migration and invasion. Here, we demonstrate that the simultaneous, siRNA-mediated down-regulation of uPAR and cathepsin B inhibits glioma cell migration and is accompanied by cytoskeletal condensation. We show that the dephosphorylation of cofilin is inhibited by the down-regulation of uPAR alone and, to a lesser extent, by the down-regulation of cathepsin B alone, and that the effect was much higher with the down-regulation of both molecules by pUC. Using FACS analysis and western blotting for the alphaVbeta3 integrin heterodimer, we determined that down-regulating uPAR subsequently causes the down-regulation of the alphaVbeta3 integrin heterodimer. As evidenced by western blot analysis of ERK1/2, pERK1/2, p38MAPK, p-p38MAPK, AKT, pAKT and PI3-k, the MEK and PI3-k pathways are inhibited. From cytoskeleton studies, we observed that the down-regulation of uPAR caused cytoskeletal condensation and that the simultaneous down-regulation of uPAR and cathepsin B was even more effective at inducing cytoskeletal condensation than uPAR alone. Our results demonstrate the relevance of uPAR in cytoskeletal dynamics and the potential of uPAR and cathepsin B as targets in the treatment of malignant gliomas.

Publication types

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

MeSH terms

  • Actin Depolymerizing Factors / metabolism*
  • Actins / metabolism
  • Apoptosis Regulatory Proteins / metabolism
  • Blotting, Western
  • Cathepsin B / genetics*
  • Cathepsin B / physiology
  • Cell Line, Tumor
  • Cytoskeleton / metabolism
  • Down-Regulation
  • Humans
  • Integrin alphaVbeta3 / metabolism
  • Models, Biological
  • Oncogene Protein v-akt / metabolism
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphorylation
  • Plasmids / genetics
  • RNA Interference
  • RNA, Small Interfering / genetics
  • Receptors, Cell Surface / genetics*
  • Receptors, Cell Surface / physiology
  • Receptors, Urokinase Plasminogen Activator
  • Transfection
  • p38 Mitogen-Activated Protein Kinases / metabolism

Substances

  • Actin Depolymerizing Factors
  • Actins
  • Apoptosis Regulatory Proteins
  • Integrin alphaVbeta3
  • PLAUR protein, human
  • RNA, Small Interfering
  • Receptors, Cell Surface
  • Receptors, Urokinase Plasminogen Activator
  • prostate apoptosis response-4 protein
  • Phosphatidylinositol 3-Kinases
  • Oncogene Protein v-akt
  • p38 Mitogen-Activated Protein Kinases
  • Cathepsin B