Diffuse intrinsic pontine glioma (DIPG) is the most deadly solid tumor in children, with rapid disease progression, poor response to therapy, and average survival less than one year from diagnosis. Epigenetic regulation of gene expression has been implicated in a variety of human diseases, including cancer. Recently, point mutations in histone H3 have been identified in up to 80% of DIPG, causing altered chromatin function and extensive transcriptome reprogramming. Here, we describe a hypothesis-driven research plan to elucidate the mechanism by which histone H3 post-translational modifications contribute to pediatric brainstem glioma (DIPG) formation and progression. A career development plan is also described to facilitate successful transition from a mentored investigator to an independent investigator. In support of the hypothesis that histone modifications in H3K27M mutant pediatric brainstem glioma contribute to disease pathogenesis, we will characterize alterations in gene expression in DIPG associated with specific histone H3 transcriptional regulatory marks. Further, we will investigate the enzymatic mechanisms responsible for these histone modifications, to determine if these represent rational therapeutic targets. In order to investigate the effect of Histone H3 modifications on gene transcription in DIPG, we will perform chromatin immunoprecipitation in association with DNA sequencing (ChIP-Seq) to characterize genomic locations of specific H3 marks, and correlate these findings with gene expression (RNA-Seq). We will then characterize the effects of altered expression of specific oncogenes (PDGFRA) and tumor suppressor genes (p21), and enzymes responsible for identified H3 modifications, on DIPG tumor biology in vitro and in vivo. Human H3K27M mutant and wild type DIPG tumor cells will be used for in vitro studies, while a mouse xenograft model of DIPG will be used for in vivo investigations.
The aims of this proposal are: 1) To determine DIPG transciptomes with respect to histone H3 modifications; 2) To elucidate the enzymatic basis of histone H3 modifications in DIPG, and determine whether specific enzymatic activities are actionable for treating DIPG; and 3) To validate specific oncogene activations and tumor suppressor gene inactivations as causally associated with DIPG malignant phenotypes The findings of this proposal will demonstrate the effect of epigenetic dysregulation on gene expression in pediatric brainstem glioma, providing novel insight on the mechanism of DIPG tumorigenesis and a potential for developing rational, effective treatment for children with this disease.

Public Health Relevance

Diffuse intrinsic pontine glioma (DIPG) is an infiltrative high-grade glioma of the brainstem affecting young children for which there is no effective treatment. Somatic mutation of genes encoding Histone H3 isoforms are found in up to 80% of DIPGs, and are associated with distinct patterns of gene expression. We hypothesize that specific post-translational modifications of Histone H3 result in altered regulation of gene expression contributing to DIPG formation, and that enzymes responsible for these modifications represent novel therapeutic targets whose inhibition could promote improved outcomes for children with this deadly disease.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Clinical Investigator Award (CIA) (K08)
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Neurological Sciences Training Initial Review Group (NST)
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Fountain, Jane W
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Northwestern University at Chicago
Schools of Medicine
United States
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Piunti, Andrea; Hashizume, Rintaro; Morgan, Marc A et al. (2017) Therapeutic targeting of polycomb and BET bromodomain proteins in diffuse intrinsic pontine gliomas. Nat Med 23:493-500
Panwalkar, Pooja; Clark, Jonathan; Ramaswamy, Vijay et al. (2017) Immunohistochemical analysis of H3K27me3 demonstrates global reduction in group-A childhood posterior fossa ependymoma and is a powerful predictor of outcome. Acta Neuropathol 134:705-714
Huang, Tina Y; Piunti, Andrea; Lulla, Rishi R et al. (2017) Detection of Histone H3 mutations in cerebrospinal fluid-derived tumor DNA from children with diffuse midline glioma. Acta Neuropathol Commun 5:28