MicroRNA-7 inhibits epithelial-to-mesenchymal transition and metastasis of breast cancer cells via targeting FAK expression

PLoS One. 2012;7(8):e41523. doi: 10.1371/journal.pone.0041523. Epub 2012 Aug 2.


Focal adhesion kinase (FAK) is an important mediator of extracellular matrix integrin signaling, cell motility, cell proliferation and cell survival. Increased FAK expression is observed in a variety of solid human tumors and increased FAK expression and activity frequently correlate with metastatic disease and poor prognosis. Herein we identify miR-7 as a direct regulator of FAK expression. miR-7 expression is decreased in malignant versus normal breast tissue and its expression correlates inversely with metastasis in human breast cancer patients. Forced expression of miR-7 produced increased E-CADHERIN and decreased FIBRONECTIN and VIMENTIN expression in breast cancer cells. The levels of miR-7 expression was positively correlated with E-CADHERIN mRNA and negatively correlated with VIMENTIN mRNA levels in breast cancer samples. Forced expression of miR-7 in aggressive breast cancer cell lines suppressed tumor cell monolayer proliferation, anchorage independent growth, three-dimensional growth in Matrigel, migration and invasion. Conversely, inhibition of miR-7 in the HBL-100 mammary epithelial cell line promoted cell proliferation and anchorage independent growth. Rescue of FAK expression reversed miR-7 suppression of migration and invasion. miR-7 also inhibited primary breast tumor development, local invasion and metastatic colonization of breast cancer xenografts. Thus, miR-7 expression is decreased in metastatic breast cancer, correlates with the level of epithelial differentiation of the tumor and inhibits metastatic progression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3' Untranslated Regions
  • Animals
  • Base Sequence
  • Breast Neoplasms / genetics*
  • Breast Neoplasms / metabolism
  • Breast Neoplasms / pathology*
  • Cell Line, Tumor
  • Cell Movement / genetics
  • Cell Proliferation
  • Down-Regulation / genetics
  • Epithelial-Mesenchymal Transition / genetics*
  • Female
  • Focal Adhesion Protein-Tyrosine Kinases / genetics*
  • Gene Expression Regulation, Neoplastic*
  • Humans
  • Mice
  • Mice, Nude
  • MicroRNAs / genetics*
  • Neoplasm Metastasis / genetics
  • Phenotype
  • Xenograft Model Antitumor Assays


  • 3' Untranslated Regions
  • MIRN7 microRNA, human
  • MicroRNAs
  • Focal Adhesion Protein-Tyrosine Kinases

Grants and funding

This work was supported by the National Key Scientific Program of China (2010CB912804,2012CB934002), National Natural Science Foundation of China (30971492), Cancer Science Institute of Singapore and the Chinese Academy of Sciences Visiting Professorship for Senior International Scientists (2010T2SO3). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.