Subependimal dev hücreli astrositomlarda belirgin olmayan farklılaşma ve mTOR yolaǧı bozuklukları

Translated title of the contribution: Evidence of ambiguous differentiation and mTOR pathway dysregulation in subependymal giant cell astrocytoma

Brad D. Barrows, Martin J. Rutkowski, Şakir Humayun Gültekin, Andrew T. Parsa, Tarik Tihan

Research output: Contribution to journalArticle

6 Scopus citations


Objective: The exact cell of origin of subependymal giant cell astrocytoma is debated but most currently consider the tumor in the astrocytic category. Mutations and subsequent biallelic inactivation of TSC1 encoding hamartin, or TSC2 encoding tuberin appear to be the underlying genetic aberrations. Inactivation leads to loss of proteins that inhibit mammalian target of rapamycin (mTOR) disrupting tightly regulated cell functions. Material and Method: We analyzed the expression of tuberin and hamartin along with an array of neuroepithelial markers in 9 subependymal giant cell astrocytomas. In addition, RPS6 and 4EBP1 regulatory proteins that are downstream in the mTOR pathway were also evaluated. Results: While hamartin and tuberin expression levels were relatively decreased compared to control tissue, this was not of particular practical use to detect the mutated gene since low levels of positivity could be detected throughout the central nervous system. As expected, the levels of RPS6 and 4EBP1 were increased, further confirming the activation of the mTOR pathway. GFAP was positive in 5 cases, while Synaptophysin positivity was found in all tumors. CD34 (a marker often observed in well differentiated glio-neuronal tumors), Olig2 (a nuclear marker present in most gliomas), IDH1 and IDH2 were entirely negative in all tumor cells. Ki67 (MIB-1) showed a low proliferation rate ranging from 2% to 8%. Conclusion: Staining with neuroepithelial markers supports the suggestion of ambiguous differentiation. Subependymal giant cell astrocytomas do not appear to have the typical expression profiles of astrocytic tumors, under which they have been classified.

Original languageTurkish
Pages (from-to)95-103
Number of pages9
JournalTurk Patoloji Dergisi/Turkish Journal of Pathology
Issue number2
StatePublished - 2012
Externally publishedYes



  • Hamartin
  • Idh1
  • Idh2
  • Mtor complex
  • Olig2
  • Subependymal giant cell astrocytoma
  • Tuberin

ASJC Scopus subject areas

  • Pathology and Forensic Medicine

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