Increase of O-glycosylated oncofetal fibronectin in high glucose-induced epithelial-mesenchymal transition of cultured human epithelial cells

PLoS One. 2013 Apr 12;8(4):e60471. doi: 10.1371/journal.pone.0060471. Print 2013.

Abstract

Growing evidences indicate that aberrant glycosylation can modulate tumor cell invasion and metastasis. The process termed "epithelial-mesenchymal transition" (EMT) provides a basic experimental model to shed light on this complex process. The EMT involves a striking decline in epithelial markers, accompanied by enhanced expression of mesenchymal markers, culminating in cell morphology change and increased cell motility. Few recent studies have established the participation glycosylation during EMT. Studies now come into knowledge brought to light the involvement of a site-specific O-glycosylation in the IIICS domain of human oncofetal fibronectin (onfFN) during the EMT process. Herein we show that high glucose induces EMT in A549 cells as demonstrated by TGF-β secretion, cell morphology changes, increased cellular motility and the emergence of mesenchymal markers. The hyperglycemic conditions increased onfFN protein levels, promoted an up regulation of mRNA levels for ppGalNAc-T6 and FN IIICS domain, which contain the hexapeptide (VTHPGY) required for onfFN biosynthesis. Glucose effect involves hexosamine (HBP) biosynthetic pathway as overexpression of glutamine: fructose-6-phosphate amidotransferase increases mesenchymal markers, onfFN levels and mRNA levels for FN IIICS domain. In summary, our results demonstrate, for the first time that the metabolism of glucose through HBP promotes O-glycosylation of the oncofetal form of FN during EMT modulating tumorogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Biomarkers / metabolism
  • Cell Line, Tumor
  • Cell Movement / drug effects
  • Cell Shape / drug effects
  • Epithelial Cells / drug effects
  • Epithelial Cells / metabolism*
  • Epithelial-Mesenchymal Transition / drug effects*
  • Fibronectins / metabolism*
  • Glucose / pharmacology*
  • Glycosylation / drug effects
  • Hexosamines / biosynthesis
  • Humans
  • Hyperglycemia / pathology
  • Mesoderm / drug effects
  • Mesoderm / metabolism
  • Molecular Sequence Data
  • Nitrogenous Group Transferases / metabolism
  • Peptides / chemistry
  • Peptides / pharmacology
  • Transforming Growth Factor beta1 / pharmacology

Substances

  • Biomarkers
  • Fibronectins
  • Hexosamines
  • Peptides
  • Transforming Growth Factor beta1
  • oncofetal fibronectin
  • Nitrogenous Group Transferases
  • Glucose

Grant support

This work was supported by grants from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) and the Instituto Nacional de Ciência e Tecnologia de Vacinas (INCT-V). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.