The RhoA pathway mediates MMP-2 and MMP-9-independent invasive behavior in a triple-negative breast cancer cell line

J Cell Biochem. 2013 Jun;114(6):1385-94. doi: 10.1002/jcb.24480.


Breast cancer is a heterogeneous disease that varies in its biology and response to therapy. A foremost threat to patients is tumor invasion and metastasis, with the greatest risk among patients diagnosed with triple-negative and/or basal-like breast cancers. A greater understanding of the molecular mechanisms underlying cancer cell spreading is needed as 90% of cancer-associated deaths result from metastasis. We previously demonstrated that the Tamoxifen-selected, MCF-7 derivative, TMX2-28, lacks expression of estrogen receptor α (ERα) and is highly invasive, yet maintains an epithelial morphology. The present study was designed to further characterize TMX2-28 cells and elucidate their invasion mechanism. We found that TMX2-28 cells do not express human epidermal growth factor receptor 2 (HER2) and progesterone receptor (PR), in addition to lacking ERα, making the cells triple-negative. We then determined that TMX2-28 cells lack expression of active matrix metalloproteinases (MMPs)-1, MMP-2, MMP-9, and other genes involved in epithelial-mesenchymal transition (EMT) suggesting that TMX2-28 may not utilize mesenchymal invasion. In contrast, TMX2-28 cells have high expression of Ras Homolog Gene Family Member, A (RhoA), a protein known to play a critical role in amoeboid invasion. Blocking RhoA activity with the RhoA pathway specific inhibitor H-1152, or a RhoA specific siRNA, resulted in inhibition of invasive behavior. Collectively, these results suggest that TMX2-28 breast cancer cells exploit a RhoA-dependent, proteolytic-independent invasion mechanism. Targeting the RhoA pathway in triple-negative, basal-like breast cancers that have a proteolytic-independent invasion mechanism may provide therapeutic strategies for the treatment of patients with increased risk of metastasis.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / analogs & derivatives
  • 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / pharmacology
  • Cell Movement
  • Epithelial-Mesenchymal Transition / genetics
  • Female
  • Humans
  • MCF-7 Cells
  • Matrix Metalloproteinase 1 / metabolism
  • Matrix Metalloproteinase 2 / physiology*
  • Matrix Metalloproteinase 9 / physiology*
  • Neoplasm Invasiveness
  • Transcriptome
  • Triple Negative Breast Neoplasms
  • rhoA GTP-Binding Protein / antagonists & inhibitors
  • rhoA GTP-Binding Protein / genetics
  • rhoA GTP-Binding Protein / metabolism*


  • 2-methyl-1-((4-methyl-5-isoquinolinyl)sulfonyl)homopiperazine
  • RHOA protein, human
  • 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine
  • MMP2 protein, human
  • Matrix Metalloproteinase 2
  • MMP9 protein, human
  • Matrix Metalloproteinase 9
  • MMP1 protein, human
  • Matrix Metalloproteinase 1
  • rhoA GTP-Binding Protein