Integrated genomics has identified a new AT/RT-like yet INI1-positive brain tumor subtype among primary pediatric embryonal tumors

Donald Ming Tak Ho, Chuan Chi Shih, Muh Lii Liang, Chan Yen Tsai, Tsung Han Hsieh, Chin Han Tsai, Shih Chieh Lin, Ting Yu Chang, Meng En Chao, Hsei Wei Wang, Tai-Tong Wong

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

Background: Pediatric embryonal brain tumors (PEBTs), which encompass medulloblastoma (MB), primitive neuroectodermal tumor (PNET) and atypical teratoid/rhabdoid tumor (AT/RT), are the second most prevalent pediatric brain tumor type. AT/RT is highly malignant and is often misdiagnosed as MB or PNET. The distinction of AT/RT from PNET/MB is of clinical significance because the survival rate of patients with AT/RT is substantially lower. The diagnosis of AT/RT relies primarily on morphologic assessment and immunohistochemical (IHC) staining for a few known markers such as the lack of INI1 protein expression. However, in our clinical practice we have observed several AT/RT-like tumors, that fulfilled histopathological and all other biomarker criteria for a diagnosis of AT/RT, yet retained INI1 immunoreactivity. Recent studies have also reported preserved INI1 immunoreactivity among certain diagnosed AT/RTs. It is therefore necessary to re-evaluate INI1(+), AT/RT-like cases. Method: Sanger sequencing, array CGH and mRNA microarray analyses were performed on PEBT samples to investigate their genomic landscapes. Results: Patients with AT/RT and those with INI(+) AT/RT-like tumors showed a similar survival rate, and global array CGH analysis and INI1 gene sequencing showed no differential chromosomal aberration markers between INI1(-) AT/RT and INI(+) AT/RT-like cases. We did not misdiagnose MBs or PNETs as AT/RT-like tumors because transcriptome profiling revealed that not only did AT/RT and INI(+) AT/RT-like cases express distinct mRNA and microRNA profiles, their gene expression patterns were different from those of MBs and PNETs. The most similar transcriptome profile to that of AT/RTs was the profile of embryonic stem cells. However; the transcriptome profile of INI1(+) AT/RT-like tumors was more similar to that of somatic neural stem cells, while the profile of MBs was closer to that of fetal brain tissue. Novel biomarkers were identified that can be used to distinguish INI1(-) AT/RTs, INI1(+) AT/RT-like cases and MBs. Conclusion: Our studies revealed a novel INI1(+) ATRT-like subtype among Taiwanese pediatric patients. New diagnostic biomarkers, as well as new therapeutic tactics, can be developed according to the transcriptome data that were unveiled in this work.

Original languageEnglish
Article number32
JournalBMC Medical Genomics
Volume8
Issue number1
DOIs
Publication statusPublished - Jun 25 2015

Keywords

  • Atypical teratoid/rhabdoid tumor
  • INI1
  • Pediatric embryonal brain tumor
  • Stem cell
  • Transcriptome

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)

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