A role for the TGFbeta-Par6 polarity pathway in breast cancer progression

Proc Natl Acad Sci U S A. 2009 Aug 18;106(33):14028-33. doi: 10.1073/pnas.0906796106. Epub 2009 Aug 10.


The role of polarity signaling in cancer metastasis is ill defined. Using two three-dimensional culture models of mammary epithelial cells and an orthotopic mouse model of breast cancer, we reveal that Par6 signaling, which is regulated directly by TGFbeta, plays a role in breast cancer metastasis. Interference with Par6 signaling blocked TGFbeta-dependent loss of polarity in acini-like structures formed by non-transformed mammary cells grown in three-dimensional structures and suppressed the protrusive morphology of mesenchymal-like invasive mammary tumor cells without rescuing E-cadherin expression. Moreover, blockade of Par6 signaling in an in vivo orthotopic model of metastatic breast cancer induced the formation of ZO-1-positive epithelium-like structures in the primary tumor and suppressed metastasis to the lungs. Analysis of the pathway in tissue microarrays of human breast tumors further revealed that Par6 activation correlated with markers of the basal carcinoma subtype in BRCA1-associated tumors. These studies thus reveal a key role for polarity signaling and the control of morphologic transformation in breast cancer metastasis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism*
  • Animals
  • Breast Neoplasms / metabolism*
  • Breast Neoplasms / pathology*
  • Disease Progression
  • Female
  • Gene Expression Regulation, Neoplastic*
  • Genes, BRCA1
  • Humans
  • Mammary Neoplasms, Animal / metabolism*
  • Mammary Neoplasms, Animal / pathology*
  • Mice
  • Mice, Inbred BALB C
  • Microscopy, Fluorescence / methods
  • Neoplasm Metastasis
  • Signal Transduction
  • Transforming Growth Factor beta / metabolism*


  • Adaptor Proteins, Signal Transducing
  • PARD6A protein, human
  • Par6 protein, mouse
  • Transforming Growth Factor beta