Targeted Next-Generation Sequencing of Dedifferentiated Chondrosarcoma in the Skull Base Reveals Combined TP53 and PTEN Mutations With Increased Proliferation Index, an Implication for Pathogenesis

Oncotarget. 2016 Jul 12;7(28):43557-43569. doi: 10.18632/oncotarget.9618.

Abstract

Dedifferentiated chondrosarcoma (DDCS) is a rare disease with a dismal prognosis. DDCS consists of two morphologically distinct components: the cartilaginous and noncartilaginous components. Whether the two components originate from the same progenitor cells has been controversial. Recurrent DDCS commonly displays increased proliferation compared with the primary tumor. However, there is no conclusive explanation for this mechanism. In this paper, we present two DDCSs in the sellar region. Patient 1 exclusively exhibited a noncartilaginous component with a TP53 frameshift mutation in the pathological specimens from the first surgery. The tumor recurred after radiation therapy with an exceedingly increased proliferation index. Targeted next-generation sequencing (NGS) revealed the presence of both a TP53 mutation and a PTEN deletion in the cartilaginous and the noncartilaginous components of the recurrent tumor. Fluorescence in situ hybridization and immunostaining confirmed reduced DNA copy number and protein levels of the PTEN gene as a result of the PTEN deletion. Patient 2 exhibited both cartilaginous and noncartilaginous components in the surgical specimens. Targeted NGS of cells from both components showed neither TP53 nor PTEN mutations, making Patient 2 a naïve TP53 and PTEN control for comparison. In conclusion, additional PTEN loss in the background of the TP53 mutation could be the cause of increased proliferation capacity in the recurrent tumor.

Keywords: PTEN; TP53; chondrosarcoma; dedifferentiated; proliferation.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Cell Dedifferentiation / genetics*
  • Cell Proliferation / genetics*
  • Cell Proliferation / radiation effects
  • Chondrosarcoma / diagnostic imaging
  • Chondrosarcoma / genetics*
  • Chondrosarcoma / radiotherapy
  • Frameshift Mutation
  • Gene Deletion
  • Gene Dosage / genetics
  • High-Throughput Nucleotide Sequencing / methods
  • Humans
  • In Situ Hybridization, Fluorescence
  • Magnetic Resonance Imaging
  • Male
  • Mitotic Index
  • Neoplasm Recurrence, Local / diagnostic imaging
  • Neoplasm Recurrence, Local / genetics*
  • PTEN Phosphohydrolase / genetics*
  • Prognosis
  • Rare Diseases / diagnostic imaging
  • Rare Diseases / genetics
  • Rare Diseases / radiotherapy
  • Skull Base / pathology
  • Tumor Suppressor Protein p53 / genetics*

Substances

  • TP53 protein, human
  • Tumor Suppressor Protein p53
  • PTEN Phosphohydrolase
  • PTEN protein, human