Addiction of mesenchymal phenotypes on the FGF/FGFR axis in oral squamous cell carcinoma cells

PLoS One. 2019 Nov 4;14(11):e0217451. doi: 10.1371/journal.pone.0217451. eCollection 2019.

Abstract

The epithelial-mesenchymal transition (EMT) is a crucial morphological event that occurs during epithelial tumor progression. ZEB1/2 are EMT transcription factors that are positively correlated with EMT phenotypes and breast cancer aggressiveness. ZEB1/2 regulate the alternative splicing and hence isoform switching of fibroblast growth factor receptors (FGFRs) by repressing the epithelial splicing regulatory proteins, ESRP1 and ESRP2. Here, we show that the mesenchymal-like phenotypes of oral squamous cell carcinoma (OSCC) cells are dependent on autocrine FGF-FGFR signaling. Mesenchymal-like OSCC cells express low levels of ESRP1/2 and high levels of ZEB1/2, resulting in constitutive expression of the IIIc-isoform of FGFR, FGFR(IIIc). By contrast, epithelial-like OSCC cells showed opposite expression profiles for these proteins and constitutive expression of the IIIb-isoform of FGFR2, FGFR2(IIIb). Importantly, ERK1/2 was constitutively phosphorylated through FGFR1(IIIc), which was activated by factors secreted autonomously by mesenchymal-like OSCC cells and involved in sustained high-level expression of ZEB1. Antagonizing FGFR1 with either inhibitors or siRNAs considerably repressed ZEB1 expression and restored epithelial-like traits. Therefore, autocrine FGF-FGFR(IIIc) signaling appears to be responsible for sustaining ZEB1/2 at high levels and the EMT phenotype in OSCC cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alternative Splicing / genetics
  • Animals
  • Carcinoma, Squamous Cell / genetics*
  • Cell Line, Tumor
  • Epithelial Cells / physiology
  • Epithelial-Mesenchymal Transition / genetics*
  • Fibroblast Growth Factors / genetics*
  • Humans
  • MAP Kinase Signaling System / genetics
  • Mice
  • Mouth Neoplasms / genetics*
  • Phenotype
  • Phosphorylation / genetics
  • Protein Isoforms / genetics
  • RNA, Small Interfering / genetics
  • Receptors, Fibroblast Growth Factor / genetics*
  • Signal Transduction / genetics

Substances

  • Protein Isoforms
  • RNA, Small Interfering
  • Receptors, Fibroblast Growth Factor
  • Fibroblast Growth Factors

Grants and funding

This study was supported by the Mitsubishi Foundation, JSPS KAKENHI grant number 18H02969, and JSPS KAKENHI grant number 15H05018.