Use of human embryonic stem cells to model pediatric gliomas with H3.3K27M histone mutation

Abstract

Over 70% of diffuse intrinsic pediatric gliomas, an aggressive brainstem tumor, harbor heterozygous mutations that create a K27M amino acid substitution (methionine replaces lysine 27) in the tail of histone H3.3. The role of the H3.3K27M mutation in tumorigenesis not fully understood. Here, we use a human embryonic stem cell system to model this tumor. We show that H3.3K27M expression synergizes with p53 loss and PDGFRA activation in neural progenitor cells derived from human embryonic stem cells, resulting in neoplastic transformation. Genome-wide analyses indicate a resetting of the transformed precursors to a developmentally more primitive stem cell state, with evidence of major modifications of histone marks at several master regulator genes. Drug screening assays identified a compound targeting the protein menin as an inhibitor of tumor cell growth in vitro and in mice.

Epigenetic modification in chromatin machinery and its deregulation in pediatric brain tumors: Insight into epigenetic therapies

“…101 Treatment with MEN1 inhibitors was previously found to decrease tumor cell growth in vitro and in mice using human embryonic stem cells to model pediatric gliomas with the H3.3K27M histone mutation. 32 Although the role of MEN1 in DIPG is unclear, these studies suggest that it may be an important therapeutic target. Further details of UTX (KDM6A) and JMJD3 (KDM6B) are described below in the section "UTX (KDM6A) and JMJD3 (KDM6B)."…”

“…The expression of the stem cell-associated genes (e.g., LIN28B, PLAG1, and PLAGL1) was also upregulated by H3.3K27M, and reducing expression of these genes inhibited tumor cell growth. 32 All together, these studies demonstrate the role of the K27M mutations on gene expression, methylation patterns, and transformative capacity. Of potential significance, in addition to the reduction in H3K27 methylation levels, overexpressing H3.3K27M in Drosophila melanogaster caused a strong increase in H3K27 acetylation levels, associated with an increased in bromodomain-containing protein 1 (BRD1) and bromodomain-containing protein 4 (BRD4) in H3.3K27M-containing nucleosomes.…”

“…31 To have a better understanding of the role of the H3.3K27M mutation in a specific cell type, another study, from Funato et al, created a model of DIPG by differentiating human embryonic stem cells into neural progenitor cells, and then transducing them with a viral vector carrying the gene encoding H3.3K27M. 32 Remarkably, the mutation was only oncogenic in a specific cell type, neural progenitors derived from embryonic stem cells, and not in undifferentiated embryonic stem cells or astrocytes derived from these cells. The neoplastic transformation occurred due to a synergy between H3.3K27M expression with p53 loss and PDGFRA activation in these particular cells.…”

Epigenomic therapies: the potential of targeting SIRT6 for the treatment of pancreatic cancer

“…As pointed out in the discussion of the study, the reactivation of Lin28b may result not only from the loss of SIRT6, but also from the loss of other epigenetic barriers, as shown for H3.3K27M histone mutations in pediatric gliomas [8]. Hence, one can assume that Lin28b reactivation may occur upon the loss of various epigenetic control mechanisms during carcinogenesis, and thus may not be a specific event for the progression of PDAC.…”

Mechanisms of Nucleosome Dynamics In Vivo

“…All are likely gain-of-function mutations in that these tumors also express normal H3.3 copies. For example, in mammalian cells, expression of the H3.3K27M protein contributes to neoplastic transformation (Funato et al 2014), and a similar neoplastic effect is seen for H3K36M/I mutations found in chondroblastomas (Lu et al 2016). A gain-of-function interpretation of these phenotypes is also supported by studies in Drosophila, whereby introduction of the K27M mutation in an H3.3 transgene results in dominant Polycomb phenotypes, consistent with methionine-27 titrating the PRC2 complex (Lewis et al 2013;Herz et al 2014).…”