EGF up-regulates miR-31 through the C/EBPβ signal cascade in oral carcinoma

PLoS One. 2014 Sep 17;9(9):e108049. doi: 10.1371/journal.pone.0108049. eCollection 2014.

Abstract

Oral squamous cell carcinoma (OSCC) is one of the most prevalent carcinomas worldwide. MicroRNAs (miRNAs) are short, non-coding RNAs that regulate gene expression and modulate physiological or pathological processes including OSCC carcinogenesis. miR-31 has been found to be up-regulated in OSCC and to act as an oncogenic miRNA. However, the molecular mechanism underlying miR-31 up-regulation in OSCC is still obscure. The activation of epidermal growth factor receptor (EGFR) signaling axis plays key roles in driving oral carcinogenesis. Our screening identified that there is up-regulation of miR-31, miR-181b and miR-222 in OSCC cells following EGF treatment. Subsequent analysis showed that EGF treatment led to AKT activation, which then resulted in miR-31 up-regulation. Moreover, EGF treatment and the AKT activation induced by exogenous expression up-regulated C/EBPβ expression. The miR-31 up-regulation induced by EGF was abrogated by AKT inhibition or by the knockdown of C/EBPβ expression. In OSCC cell subclones stably overexpressing the functional isoform of C/EBPβ, miR-31 expression was up-regulated. Curcumin is a natural ingredient exhibiting anti-cancer potential. It was found that curcumin attenuated AKT activation and the up-regulation of C/EBPβ and miR-31 caused by EGF stimulation in OSCC cells. Lastly, concordance across the expression of EGFR, the expression of C/EBPβ and the expression of miR-31 in OSCC tissues was found. This study describes a novel scenario where the up-regulation of miR-31 expression in OSCC is, at least in part, a consequence of EGFR oncogenic activation. Although the AKT activation and C/EBPβ expression after EGF treatment might not be directly linked, both events are the crucial mediators underlying miR-31 up-regulation in the EGFR signaling axis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • CCAAT-Enhancer-Binding Protein-beta / metabolism*
  • Carcinoma, Squamous Cell / pathology*
  • Cell Line, Tumor
  • Curcumin / pharmacology
  • Epidermal Growth Factor / pharmacology*
  • Humans
  • MicroRNAs / genetics*
  • Mouth Mucosa / drug effects
  • Mouth Mucosa / metabolism
  • Mouth Mucosa / pathology
  • Mouth Neoplasms / pathology*
  • Proto-Oncogene Proteins c-akt / antagonists & inhibitors
  • Proto-Oncogene Proteins c-akt / metabolism
  • Signal Transduction / drug effects*
  • Up-Regulation / drug effects*

Substances

  • CCAAT-Enhancer-Binding Protein-beta
  • MIRN31 microRNA, human
  • MicroRNAs
  • Epidermal Growth Factor
  • Proto-Oncogene Proteins c-akt
  • Curcumin

Grants and funding

This study was supported by grants NSC-102-2628-B-010-011-MY3 and NSC-102-2314-B-010-035 from National Science Council and Taipei Veterans General Hospital grant V102C-062. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.