EWSR1-PATZ1 gene fusion may define a new glioneuronal tumor entity

Brain Pathol. 2019 Jan;29(1):53-62. doi: 10.1111/bpa.12619. Epub 2018 Jul 13.

Abstract

We investigated the challenging diagnostic case of a ventricular cystic glioneuronal tumor with papillary features, by RNA sequencing using the Illumina TruSight RNA Fusion panel. We did not retrieve the SLC44A1-PRKCA fusion gene specific for papillary glioneuronal tumor, but an EWSR1-PATZ1 fusion transcript. RT-PCR followed by Sanger sequencing confirmed the EWSR1-PATZ1 fusion. It matched with canonic EWSR1 fusion oncogene, juxtaposing the entire N-terminal transcriptional activation domain of EWSR1 gene and the C-terminal DNA binding domain of a transcription factor gene, PATZ1. PATZ1 protein belongs to the BTB-ZF (broad-complex, tramtrack and bric-à-brac -zinc finger) family. It directly regulates Pou5f1 and Nanog and is essential to maintaining stemness by inhibiting neural differentiation. EWSR1-PATZ1 fusion is a rare event in tumors: it was only reported in six round cell sarcomas and in three gliomas of three exclusively molecular studies. The first reported glioma was a BRAFV600E negative ganglioglioma, the second a BRAFV600E negative glioneuronal tumor, not otherwise specified and the third, very recently reported, a high grade glioma, not otherwise specified. In our study, forty BRAFV600E negative gangliogliomas were screened by FISH using EWSR1 break-apart probes. We performed methylation profiling for the index case and for seven out of the ten FISH positive cases. The index case clustered apart from other pediatric low grade glioneuronal entities, and specifically from the well-defined ganglioglioma methylation group. An additional pediatric intraventricular ganglioglioma clustered slightly more closely with ganglioglioma, but showed differences from the main ganglioglioma group and similarities with the index case. Both cases harbored copy number variations at the PATZ1 locus. EWSR1-PATZ1 gene fusion might define a new type of glioneuronal tumors, distinct from gangliogliomas.

Keywords: DNA methylation profiling; EWSR1; PATZ1; ganglioglioma; glioneuronal tumors.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Biomarkers, Tumor / genetics
  • Brain Neoplasms / pathology
  • Child
  • DNA Copy Number Variations
  • DNA Methylation
  • Female
  • Ganglioglioma / genetics*
  • Ganglioglioma / metabolism
  • Gene Fusion
  • Glioma / genetics
  • Humans
  • In Situ Hybridization, Fluorescence
  • Kruppel-Like Transcription Factors / genetics*
  • Kruppel-Like Transcription Factors / metabolism
  • Male
  • Neoplasms, Neuroepithelial / genetics
  • RNA-Binding Protein EWS / genetics*
  • RNA-Binding Protein EWS / metabolism
  • Repressor Proteins / genetics*
  • Repressor Proteins / metabolism

Substances

  • Biomarkers, Tumor
  • EWSR1 protein, human
  • Kruppel-Like Transcription Factors
  • PATZ1 protein, human
  • RNA-Binding Protein EWS
  • Repressor Proteins