EMT-induced stemness and tumorigenicity are fueled by the EGFR/Ras pathway

PLoS One. 2013 Aug 12;8(8):e70427. doi: 10.1371/journal.pone.0070427. eCollection 2013.

Abstract

Recent studies have revealed that differentiated epithelial cells would acquire stem cell-like and tumorigenic properties following an Epithelial-Mesenchymal Transition (EMT). However, the signaling pathways that participate in this novel mechanism of tumorigenesis have not been fully characterized. In Runx3 (-/-) p53 (-/-) murine gastric epithelial (GIF-14) cells, EMT-induced plasticity is reflected in the expression of the embryonal proto-oncogene Hmga2 and Lgr5, an exclusive gastrointestinal stem cell marker. Here, we report the concurrent activation of an EGFR/Ras gene expression signature during TGF-β1-induced EMT in GIF-14 cells. Amongst the altered genes was the induction of Egfr, which corresponded with a delayed sensitization to EGF treatment in GIF-14. Co-treatment with TGF-β1 and EGF or the expression of exogenous KRas led to increased Hmga2 or Lgr5 expression, sphere initiation and colony formation in soft agar assay. Interestingly, the gain in cellular plasticity/tumorigenicity was not accompanied by increased EMT. This uncoupling of EMT and the induction of plasticity reveals an involvement of distinct signaling cues, whereby the EGFR/Ras pathway specifically promotes stemness and tumorigenicity in EMT-altered GIF-14 cells. These data show that the EGFR/Ras pathway requisite for the sustenance of gastric stem cells in vivo and in vitro is involved in the genesis and promotion of EMT-induced tumor-initiating cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Cell Transformation, Neoplastic / genetics
  • Cell Transformation, Neoplastic / metabolism*
  • Cluster Analysis
  • Epidermal Growth Factor / pharmacology
  • Epithelial-Mesenchymal Transition* / genetics
  • ErbB Receptors / genetics
  • ErbB Receptors / metabolism*
  • Gene Expression Regulation / drug effects
  • Mice
  • Models, Biological
  • Proto-Oncogene Proteins p21(ras) / genetics
  • Proto-Oncogene Proteins p21(ras) / metabolism*
  • Signal Transduction* / drug effects
  • Spheroids, Cellular
  • Stem Cells / drug effects
  • Stem Cells / metabolism*
  • Transcriptome
  • Transforming Growth Factor beta1 / pharmacology
  • Tumor Cells, Cultured

Substances

  • Transforming Growth Factor beta1
  • Epidermal Growth Factor
  • ErbB Receptors
  • Proto-Oncogene Proteins p21(ras)

Grant support

This work is supported in part by the National Research Foundation (NRF, http://www.nrf.gov.sg), Translational and Clinical Research (TCR) Flagship Programme (http://www.nmrc.gov.sg), and the Singapore Stem Cell Consortium (SSCC, http://www.sscc.a-star.edu.sg) grant number SSCC/10/023. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.