Reduction of c-Fos via Overexpression of miR-34a Results in Enhancement of TNF- Production by LPS in Neutrophils from Myelodysplastic Syndrome Patients

PLoS One. 2016 Aug 11;11(8):e0158527. doi: 10.1371/journal.pone.0158527. eCollection 2016.

Abstract

Although increased TNF-α has been considered to cause ineffective hematopoiesis in myelodysplastic syndromes (MDS), the mechanisms of TNF-α elevation are not known. We recently found that c-Fos mRNA stabilization under translation-inhibiting stimuli was impaired in MDS-derived neutrophilic granulocytes. In the current study, we identified overexpression of c-Fos-targeting miR-34a and miR-155 as the cause of impairment. Expression levels of miR-34a but not miR-155 inversely correlated with ratios of c-Fos-positive cells in MDS-derived CD16+ neutrophils (r = -0.618, P<0.05), which were analyzed by flow cytometry. Among the seventeen patients, c-Fos was detectable in less than 60% of CD16+ cells in eight patients (Group A), while five (Group B) expressed c-Fos in more than 80% of CD16+ cells, which was consistent with the controls (88.6 ± 7.8%). Group A-derived granulocytes secreted more TNF-α in response to 1 μM LPS for 3 hours (735.4 ± 237.5 pg/mL) than Group B (143.5 ± 65.7 pg/mL, P<0.05) and healthy controls (150.8 ± 91.5 pg/mL, P<0.05). Knockdown of c-Fos in neutrophil-like differentiated HL60 increased the binding of NF-κB p65 to the promoter region of TNF-α DNA. Thus, c-Fos reduction via overexpression of miR-34a contributes to TNF-α overproduction under inflammatory stimuli in MDS.

Publication types

  • Comparative Study

MeSH terms

  • Aged
  • Aged, 80 and over
  • Case-Control Studies
  • Cell Differentiation / drug effects
  • Female
  • Gene Expression Regulation / drug effects*
  • Granulocytes / drug effects
  • Granulocytes / metabolism
  • Granulocytes / pathology
  • Humans
  • Lipopolysaccharides / pharmacology*
  • Male
  • MicroRNAs / genetics*
  • Middle Aged
  • Myelodysplastic Syndromes / genetics
  • Myelodysplastic Syndromes / immunology
  • Myelodysplastic Syndromes / metabolism*
  • NF-kappa B / genetics
  • NF-kappa B / metabolism
  • Neutrophils / drug effects
  • Neutrophils / metabolism
  • Neutrophils / pathology
  • Proto-Oncogene Proteins c-fos / antagonists & inhibitors*
  • Proto-Oncogene Proteins c-fos / genetics
  • Proto-Oncogene Proteins c-fos / metabolism
  • Signal Transduction / drug effects
  • Tumor Necrosis Factor-alpha / metabolism*

Substances

  • Lipopolysaccharides
  • MIRN34 microRNA, human
  • MicroRNAs
  • NF-kappa B
  • Proto-Oncogene Proteins c-fos
  • Tumor Necrosis Factor-alpha

Grants and funding

This study was supported by the Japanese Society for Promotion of Science Grant-in-Aids for Scientific Research (C) [MO23591400] to YS, [MO26461409] to YS, and [MO24590325] to JK.