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A Protocol for Rapid Post-mortem Cell Culture of Diffuse Intrinsic Pontine Glioma DIPG
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A Protocol for Rapid Post-mortem Cell Culture of Diffuse Intrinsic Pontine Glioma DIPG

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PTEN regulates glioblastoma oncogenesis through chromatin-associated complexes of DAXX and histone H3.3

Jorge A Benitez1, Jianhui Ma1, Matteo D'Antonio2,3

  • 1Ludwig Institute for Cancer Research, La Jolla, California 92093-0660, USA.

Nature Communications
|May 13, 2017
PubMed

Insights

PTEN loss in glioblastoma involves a new chromatin role. Inhibiting DAXX, a protein interacting with PTEN, suppresses tumor growth by altering histone H3.3 distribution.

Area of Science:

  • Oncology
  • Molecular Biology
  • Epigenetics

Background:

  • Glioblastoma (GBM) is an aggressive brain cancer with frequent PTEN tumor suppressor gene alterations.
  • PTEN loss is linked to therapeutic resistance and poor prognosis in GBM.
  • A novel chromatin-associated function of PTEN is investigated.

Purpose of the Study:

  • To elucidate the non-enzymatic, chromatin-associated function of PTEN.
  • To explore the interaction between PTEN, DAXX, and H3.3 in glioblastoma.
  • To evaluate DAXX inhibition as a therapeutic strategy for PTEN-deficient GBM.

Main Methods:

  • Co-immunoprecipitation to assess protein interactions.
  • Chromatin immunoprecipitation to analyze histone modifications and occupancy.
  • Orthotopic mouse xenograft models using human PTEN-deficient glioma cells.
  • Analysis of PTEN and DAXX expression in GBM patient samples.

Main Results:

  • PTEN interacts with the histone chaperone DAXX and modulates DAXX-H3.3 complex formation on chromatin.
  • PTEN regulates oncogene expression via DAXX-H3.3 interaction, independent of its phosphatase activity.
  • DAXX inhibition in mice with PTEN-deficient gliomas suppressed tumor growth and improved survival.
  • DAXX inhibition led to global H3.3 redistribution, upregulating tumor suppressors and downregulating oncogenes.
  • DAXX expression inversely correlates with PTEN expression in GBM patient tumors.

Conclusions:

  • PTEN functions in a novel chromatin complex with DAXX and H3.3 to regulate gene expression.
  • DAXX inhibition presents a targeted therapeutic strategy for PTEN-deficient glioblastomas.
  • This synthetic lethality approach offers a promising avenue for treating a subset of aggressive brain cancers.

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