Proteomic identification of lynchpin urokinase plasminogen activator receptor protein interactions associated with epithelial cancer malignancy

J Proteome Res. 2007 Mar;6(3):1016-28. doi: 10.1021/pr060518n.


Urokinase plasminogen activator (uPA) and its high affinity receptor (uPAR) play crucial proteolytic and non-proteolytic roles in cancer metastasis. In addition to promoting plasmin-mediated degradation of extracellular matrix barriers, cell surface engagement of uPA through uPAR binding results in the activation of a suite of diverse cellular signal transduction pathways. Because uPAR is bound to the plasma membrane through a glycosyl-phosphatidylinositol anchor, these signalling sequelae are thought to occur through the formation of multi-protein cell surface complexes involving uPAR. To further characterize uPAR-driven protein complexes, we co-immunoprecipitated uPAR from the human ovarian cancer cell line, OVCA 429, and employed sensitive proteomic methods to identify the uPAR-associated proteins. Using this strategy, we identified several known, as well as numerous novel, uPAR associating proteins, including the epithelial restricted integrin, alphavbeta6. Reverse immunoprecipitation using anti-beta6 integrin subunit monoclonal antibodies confirmed the co-purification of this protein with uPAR. Inhibition of uPAR and/or beta6 integrin subunit using neutralizing antibodies resulted in the inhibition of uPA-mediated ERK 1/2 phosphorylation and subsequent cell proliferation. These data suggest that the association of beta6 integrin (and possibly other lynchpin cancer regulatory proteins) with uPAR may be crucial in co-transmitting uPA signals that induce cell proliferation. Our findings support the notion that uPAR behaves as a lynchpin in promoting tumorigenesis by forming functionally active multiprotein complexes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antigens, Neoplasm / metabolism
  • Cell Line, Tumor
  • Cell Proliferation
  • Epithelium / pathology
  • Female
  • Humans
  • Immunoprecipitation
  • Integrin beta Chains / metabolism
  • Integrins / metabolism
  • Mitogen-Activated Protein Kinase 3 / metabolism
  • Multiprotein Complexes / metabolism
  • Ovarian Neoplasms / etiology*
  • Ovarian Neoplasms / pathology
  • Phosphorylation
  • Proteomics / methods*
  • Receptors, Cell Surface / metabolism*
  • Receptors, Urokinase Plasminogen Activator


  • Antigens, Neoplasm
  • Integrin beta Chains
  • Integrins
  • Multiprotein Complexes
  • PLAUR protein, human
  • Receptors, Cell Surface
  • Receptors, Urokinase Plasminogen Activator
  • integrin alphavbeta6
  • integrin beta6
  • Mitogen-Activated Protein Kinase 3