Cell signaling by urokinase-type plasminogen activator receptor induces stem cell-like properties in breast cancer cells

Cancer Res. 2010 Nov 1;70(21):8948-58. doi: 10.1158/0008-5472.CAN-10-1936. Epub 2010 Oct 12.


Signaling by urokinase-type plasminogen activator receptor (uPAR) can cause epithelial-mesenchymal transition (EMT) in cultured breast cancer cells. In this report, we show that uPAR signaling can also induce cancer stem cell (CSC)-like properties. Ectopic overexpression of uPAR in human MDA-MB-468 breast cancer cells promoted the emergence of a CD24(-)/CD44(+) phenotype, characteristic of CSCs, while increasing the cell surface abundance of integrin subunits β1/CD29 and α6/CD49f that represent putative mammary gland stem cell biomarkers. uPAR overexpression increased mammosphere formation in vitro and tumor formation in an immunocompromized severe combined immunodeficient (SCID) mouse model of orthotopic breast cancer. Hypoxic conditions that are known to induce EMT in MDA-MB-468 cells also increased cell surface β1/CD29, mimicking the effects of uPAR overexpression. Antagonizing uPAR effector signaling pathways reversed the increase in cell surface integrin expression. Whereas uPAR overexpression did not induce EMT in MCF-7 breast cancer cells, CSC-like properties were nevertheless still induced along with an increase in tumor initiation and growth in the orthotopic setting in SCID mice. Notably, in MCF-7 cell mammospheres, which display a well-defined acinus-like structure with polarized expression of E-cadherin and β1-integrin, cell collapse into the central cavity was decreased by uPAR overexpression, suggesting that uPAR signaling may stabilize epithelial morphology. In summary, our findings show that uPAR signaling can induce CSC-like properties in breast cancer cells, either concomitantly with or separately from EMT.

Publication types

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

MeSH terms

  • Animals
  • Biotinylation
  • Blotting, Western
  • Breast Neoplasms / metabolism*
  • Breast Neoplasms / pathology*
  • Cell Adhesion
  • Cell Membrane / metabolism
  • Cell Movement*
  • Epithelial Cells / metabolism
  • Female
  • Flow Cytometry
  • Fluorescent Antibody Technique
  • Humans
  • Integrin beta1 / metabolism
  • Membrane Proteins / metabolism
  • Mesoderm / cytology
  • Mesoderm / metabolism
  • Mice
  • Mice, SCID
  • Neoplastic Stem Cells / metabolism
  • Neoplastic Stem Cells / pathology*
  • RNA, Messenger / genetics
  • Receptors, Urokinase Plasminogen Activator / genetics
  • Receptors, Urokinase Plasminogen Activator / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction*
  • Tumor Cells, Cultured


  • Integrin beta1
  • Membrane Proteins
  • RNA, Messenger
  • Receptors, Urokinase Plasminogen Activator