Project description:We assessed changes in chromatin accessibility in H3.3K27M DIPG cell lines on knockdown of metabolic enzymes including HK2, GDH and IDH1
Project description:The lysine-to-methionine mutation at residue 27 of histone H3 (H3K27M) is a driving mutation in Diffuse Intrinsic Pontine Glioma (DIPG), a highly aggressive form of pediatric brain tumor with no effective treatment and little chance of survival. H3K27M reshapes the epigenome through a global inhibition of PRC2 catalytic activity, displacement of methylation at lysine 27 of histone H3 (H3K27me2/3), and thus promoting oncogenesis of DIPG. As a consequence, a histone modification H3K36me2, antagonistic to H3K27me2/3, is aberrantly elevated. Here, we investigate the role of H3K36me2 in H3K27M-DIPG by tackling its upstream catalyzing enzymes (writers) and downstream binding factors (readers). We determine that NSD1 and NSD2 are the key writers for H3K36me2. Loss of NSD1/2 in H3K27M-DIPG impedes cellular proliferation in vitro and tumorigenesis in vivo, and disrupts tumor-promoting gene expression programs. Further, we demonstrate that LEDGF and HDGF2 are the main readers that mediate the pro-tumorigenic effects downstream of NSD1/2-H3K36me2. Treatment with a chemically modified peptide mimicking endogenous H3K36me2 dislodges LEDGF/HDGF2 from chromatin and specifically inhibits the proliferation of H3K27M-DIPG. Together, our results indicate a functional pathway of NSD1/2-H3K36me2-LEDGF/HDGF2 as an acquired dependency in H3K27M-DIPG and suggest a possibility to target this pathway for therapeutic interventions.
Project description:Diffuse intrinsic pontine gliomas (DIPGs) are lethal pediatric brain tumors with limited therapeutic options. Frequently harboring H3K27M mutations, these tumors are resistant to Histone deacetylase inhibitors (HDACi) in clinical trials for yet unclear reasons. Given this, there is a critical need for exploring the reasons of insufficient clinical manifestations of HDACi and identifying effective combinatorial therapeutic strategy for the treatment of DIPG. To explore the possibility of combining HDACi with EC-8042, an analog of Mithramycin that blocks the DNA binding of SP/KLF factors, We performed RNA-seq in SU-DIPG-IV and SU-DIPG-XVII cells after treated with DMSO, vorinostat and combination vorinostat with EC-8042. And revealed that HDACi treatment amplifies the expression of hypoxia-responsive genes and promotes tumor invasiveness, which is efficiently counteracted by EC8042. And EC-8042 in combination with HDACi synergistically represses the expression of cell cycle-associated genes and therefore suppresses H3K27M-DIPG cell proliferation, inhibiting tumor progression in orthotopic xenograft models. Transcriptomic analysis further supports that the combination treatment drives transcriptional programs correlating with favorable prognosis in DIPG patients. Therefore, our regulome profiling in H3K27M-DIPGs has provided mechanistic insights into HDACi resistance and a proof-of-concept for novel targeting therapeutics.
Project description:Diffuse intrinsic pontine gliomas (DIPGs) are lethal pediatric brain tumors with limited therapeutic options. Frequently harboring H3K27M mutations, these tumors are resistant to Histone deacetylase inhibitors (HDACi) in clinical trials for yet unclear reasons. Given this, there is a critical need for exploring the reasons of insufficient clinical manifestations of HDACi and identifying effective combinatorial therapeutic strategy for the treatment of DIPG. Using ATAC-seq, we identified that HDACi cause heightened accessibility, and the HDACi-opened chromatin regions are highly enriched for SP/KLF motifs. To explore the possibility of combining HDACi with EC-8042, an analog of Mithramycin that blocks the DNA binding of SP/KLF factors,We performed ATAC-seq in SU-DIPG-XVII cells after treated with DMSO, vorinostat and combination vorinostat with EC-8042. And discovered that EC-8042 reverses the gained accessibility caused by HDACi.
Project description:Lysine 27 to methionine mutation (H3K27M) of the H3F3A gene, which encodes the variant histone H3.3, is found in the majority of Diffuse Intrinsic Pontine Gliomas (DIPGs). DIPGs are the most aggressive form of pediatric gliomas and have a median survival of <1 year from diagnosis. As H3K27M mutation is necessary but not sufficient to cause DIPGs, it is accompanied by several other mutations in tumors. However, the mechanisms by which H3K27M increases vulnerability to DIPG tumorigenesis, while expected to involve altered epigenetic regulation is unclear. Thus, in this work we built pairs of isogenic human embryonic stem cell lines with versus without this mutation, in the absence of other DIPG contributory mutations, to investigate mechanisms by which H3K27M mutation could affect cellular proliferation and differentiation and how these were related to alterations in the transcriptome, H3K27me3, and the DNA methylome. We found that H3K27M increased stem cell proliferation and interfered with differentiation, resulting in loss of most H3K27me3 and resulting in anomalous onset of expression of developmental genes during multilineage or directed differentiation. This work suggests mechanisms by which H3K27M mutation influences stem cell properties, contributing to DIPG tumorigenesis.
Project description:Lysine 27 to methionine mutation (H3K27M) of the H3F3A gene, which encodes the variant histone H3.3, is found in the majority of Diffuse Intrinsic Pontine Gliomas (DIPGs). DIPGs are the most aggressive form of pediatric gliomas and have a median survival of <1 year from diagnosis. As H3K27M mutation is necessary but not sufficient to cause DIPGs, it is accompanied by several other mutations in tumors. However, the mechanisms by which H3K27M increases vulnerability to DIPG tumorigenesis, while expected to involve altered epigenetic regulation is unclear. Thus, in this work we built pairs of isogenic human embryonic stem cell lines with versus without this mutation, in the absence of other DIPG contributory mutations, to investigate mechanisms by which H3K27M mutation could affect cellular proliferation and differentiation and how these were related to alterations in the transcriptome, H3K27me3, and the DNA methylome. We found that H3K27M increased stem cell proliferation and interfered with differentiation, resulting in loss of most H3K27me3 and resulting in anomalous onset of expression of developmental genes during multilineage or directed differentiation. This work suggests mechanisms by which H3K27M mutation influences stem cell properties, contributing to DIPG tumorigenesis.
Project description:Lysine 27 to methionine mutation (H3K27M) of the H3F3A gene, which encodes the variant histone H3.3, is found in the majority of Diffuse Intrinsic Pontine Gliomas (DIPGs). DIPGs are the most aggressive form of pediatric gliomas and have a median survival of <1 year from diagnosis. As H3K27M mutation is necessary but not sufficient to cause DIPGs, it is accompanied by several other mutations in tumors. However, the mechanisms by which H3K27M increases vulnerability to DIPG tumorigenesis, while expected to involve altered epigenetic regulation is unclear. Thus, in this work we built pairs of isogenic human embryonic stem cell lines with versus without this mutation, in the absence of other DIPG contributory mutations, to investigate mechanisms by which H3K27M mutation could affect cellular proliferation and differentiation and how these were related to alterations in the transcriptome, H3K27me3, and the DNA methylome. We found that H3K27M increased stem cell proliferation and interfered with differentiation, resulting in loss of most H3K27me3 and resulting in anomalous onset of expression of developmental genes during multilineage or directed differentiation. This work suggests mechanisms by which H3K27M mutation influences stem cell properties, contributing to DIPG tumorigenesis.
Project description:Diffuse intrinsic pontine gliomas (DIPGs) are lethal pediatric brain tumors with limited therapeutic options. Frequently harboring H3K27M mutations, these tumors are resistant to Histone deacetylase inhibitors (HDACi) in clinical trials for yet unclear reasons. Given this, there is a critical need for exploring the reasons of insufficient clinical manifestations of HDACi and identifying effective combinatorial therapeutic strategy for the treatment of DIPG. To explore the possibility of combining HDACi with EC-8042, an analog of Mithramycin that blocks the DNA binding of SP/KLF factors,We performed ChIP-seq of H3K27ac in SU-DIPG-XVII cells after treated with DMSO, vorinostat and combination vorinostat with EC-8042. And discovered that EC-8042 reverses the activated transcriptional programs caused by HDACi.
Project description:Diffuse intrinsic pontine gliomas (DIPG) are characterized by a heterozygous lysine-to-methionine mutation of histone H3 (H3K27M) that potently reduces Polycomb Repressive Complex 2 (PRC2) methylation of wild-type histone H3K27 (H3K27wt). The role of H3K27M and reduced H3K27wt methylation in DIPG pathogenesis has yet to be determined. Here, we have performed epigenomic profiling of patient-derived H3K27M mutant DIPG cells and demonstrate that H3K27M resides in nucleosomes with H3K27wt acetylation (H3K27ac), and H3K27M-H3K27ac containing nucleosomes co-localize with bromodomain proteins at actively transcribed genes and that PRC2 is excluded from H3K27M occupied regions. With respect to therapeutic implications of these observations, we demonstrate that pharmacologic bromodomain protein inhibition suppresses tumor growth in vivo. In total, our results indicate that H3K27M promotes H3K27ac at the expense of H3K27 methylation, and points to bromodomain protein inhibition as a clinical strategy for treating DIPG.