The EWSR1/NR4A3 fusion protein of extraskeletal myxoid chondrosarcoma activates the PPARG nuclear receptor gene

J Pathol. 2009 Jan;217(1):83-93. doi: 10.1002/path.2445.

Abstract

The NR4A3 nuclear receptor is implicated in the development of extraskeletal myxoid chondrosarcoma (EMC), primitive sarcoma unrelated to conventional chondrosarcomas, through a specific fusion with EWSR1 resulting in an aberrant fusion protein that is thought to disrupt the transcriptional regulation of specific target genes. We performed an expression microarray analysis of EMC tumours expressing the EWSR1/NR4A3 fusion protein, comparing their expression profiles to those of other sarcoma types. We thereby identified a set of genes significantly overexpressed in EMC relative to other sarcomas, including PPARG and NDRG2. Western blot or immunohistochemical analyses confirm that PPARG and NDRG2 are expressed in tumours positive for EWSR1/NR4A3. Bioinformatic analysis identified a DNA response element for EWSR1/NR4A3 in the PPARG promoter, and band-shift experiments and transient transfections indicate that EWSR1/NR4A3 can activate transcription through this element. Western blots further show that an isoform of the native NR4A3 receptor lacking the C-terminal domain is very highly expressed in tumours positive for EWSR1/NR4A3, and co-transfections of this isoform along with EWSR1/NR4A3 indicate that it may negatively regulate the activity of the fusion protein on the PPARG promoter. These results suggest that the overall expression of PPARG in EMC may be regulated in part by the balance between EWSR1/NR4A3 and NR4A3, and that PPARG may play a crucial role in the development of these tumours. The specific up-regulation of PPARG by EWSR1/NR4A3 may also have potential therapeutic implications.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Calmodulin-Binding Proteins / physiology*
  • Chondrosarcoma / genetics
  • Chondrosarcoma / metabolism*
  • DNA-Binding Proteins / metabolism
  • DNA-Binding Proteins / physiology*
  • Electrophoretic Mobility Shift Assay / methods
  • Gene Expression Profiling / methods
  • Humans
  • Immediate-Early Proteins / biosynthesis
  • Immediate-Early Proteins / genetics
  • Molecular Sequence Data
  • Neoplasm Proteins / metabolism
  • Neoplasm Proteins / physiology
  • Oligonucleotide Array Sequence Analysis / methods
  • Oncogene Proteins, Fusion / metabolism
  • Oncogene Proteins, Fusion / physiology*
  • PPAR gamma / genetics*
  • PPAR gamma / metabolism
  • Protein-Serine-Threonine Kinases / biosynthesis
  • Protein-Serine-Threonine Kinases / genetics
  • RNA, Messenger / genetics
  • RNA, Neoplasm / genetics
  • RNA-Binding Protein EWS
  • RNA-Binding Proteins / physiology*
  • Receptors, Steroid / metabolism
  • Receptors, Steroid / physiology*
  • Receptors, Thyroid Hormone / metabolism
  • Receptors, Thyroid Hormone / physiology*
  • Reverse Transcriptase Polymerase Chain Reaction / methods
  • Transcriptional Activation

Substances

  • Calmodulin-Binding Proteins
  • DNA-Binding Proteins
  • EWSR1 protein, human
  • Immediate-Early Proteins
  • NR4A3 protein, human
  • Neoplasm Proteins
  • Oncogene Proteins, Fusion
  • PPAR gamma
  • RNA, Messenger
  • RNA, Neoplasm
  • RNA-Binding Protein EWS
  • RNA-Binding Proteins
  • Receptors, Steroid
  • Receptors, Thyroid Hormone
  • Protein-Serine-Threonine Kinases
  • serum-glucocorticoid regulated kinase