Py2T murine breast cancer cells, a versatile model of TGFβ-induced EMT in vitro and in vivo

PLoS One. 2012;7(11):e48651. doi: 10.1371/journal.pone.0048651. Epub 2012 Nov 7.

Abstract

Introduction: Increasing evidence supports a role of an epithelial to mesenchymal transition (EMT) process in endowing subsets of tumor cells with properties driving malignant tumor progression and resistance to cancer therapy. To advance our understanding of the underlying mechanisms, we sought to generate a transplantable cellular model system that allows defined experimental manipulation and analysis of EMT in vitro and at the same time recapitulates oncogenic EMT in vivo.

Methodology/results: We have established a stable murine breast cancer cell line (Py2T) from a breast tumor of an MMTV-PyMT transgenic mouse. Py2T cells display a metastable epithelial phenotype characterized by concomitant expression of luminal and basal cytokeratins and sheet migration. Exposure of Py2T cells to transforming growth factor β (TGFβ) in vitro induces reversible EMT accompanied by downregulation of E-cadherin and upregulation of mesenchymal markers, including EMT transcription factors, and a gain in single cell motility and invasiveness. Py2T cells give rise to tumors after orthotopic injection into syngeneic FVB/N mice. Notably, transplantation of epithelial Py2T cells results in the formation of invasive primary tumors with low to absent E-cadherin expression, indicating that the cells undergo EMT-like changes in vivo. This process appears to at least in part depend on TGFβ signaling, since tumors formed by Py2T cells expressing a dominant-negative version of TGFβ receptor widely maintain their epithelial differentiation status.

Conclusions/significance: Together, the data demonstrate that the Py2T cell line represents a versatile model system to study the EMT process in vitro and in vivo. The observation that Py2T cells give rise to tumors and collectively undergo EMT-like changes in vivo highlights the suitability of the Py2T model system as a tool to study tumor-related EMT. In particular, Py2T cells may serve to corroborate recent findings relating EMT to cancer cell stemness, to therapy resistance and to tumor recurrence.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line, Tumor
  • Cell Movement / drug effects
  • Cell Shape / drug effects
  • Disease Models, Animal
  • Epithelial Cells / drug effects
  • Epithelial Cells / pathology
  • Epithelial-Mesenchymal Transition / drug effects*
  • Female
  • Humans
  • Kinetics
  • Mammary Neoplasms, Animal / pathology*
  • Mice
  • Mice, Transgenic
  • Neoplasm Invasiveness
  • Neoplasm Transplantation
  • Phenotype
  • Signal Transduction / drug effects
  • Transforming Growth Factor beta / pharmacology*

Substances

  • Transforming Growth Factor beta

Grant support

This work was supported by the Swiss National Science Foundation, the SystemsX.ch RTD project Cellplasticity, and the Krebsliga Beider Basel. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.