Histone Tail Analysis Reveals H3K36me2 And H4K16ac As Epigenetic Signatures of Diffuse Intrinsic Pontine Glioma

Abstract

Background: Diffuse intrinsic pontine glioma (DIPG) is an aggressive pediatric brainstem tumor. Most DIPGs harbor a histone H3 mutation, which alters histone post-translational modification (PTM) states and transcription. Here, we employed quantitative proteomic analysis to elucidate the impact of H3.3K27M mutation, as well as radiation and bromodomain inhibition (BRDi) with JQ1, on DIPG PTM profiles.Methods: We performed targeted mass spectroscopy on H3.3K27M mutant and wild-type tissues (n=12) and cell lines (n=7).Results: We found 29.2% and 26.4% of total H3.3K27 peptides were H3.3K27M in mutant DIPG tumor cell lines and tissue specimens, respectively. Significant differences in distinct PTMs were observed in H3.3K27M specimens, including at H3K27, H3K36, and H4K16 amino acid residues. In addition, H3.3K27me1 and H4K16ac were the most significantly distinct modifications in H3.3K27M mutant tumors relative to wild-type. Further, H3.3K36me2 was the most abundant modification co-occurring on the H3.3K27M mutant peptide in DIPG tissue, while H4K16ac was the most acetylated residue. Radiation treatment caused changes in PTM abundance in vitro, including increased H3K9me3. BRDi with JQ1 resulted in increased mono- and di-methylation of H3.1K27, H3.3K27, H3.3K36 and H4K20 in vitro. Conclusion: Taken together, our findings provide insight into the effects of the H3K27M mutation on Histone modification states and response to treatment, and suggest H3K36me2 and H4K16ac in DIPG may represent unique tumor epigenetic signatures for targeted therapy.

The H3K36me2 writer-reader dependency in H3K27M-DIPG

“…Previously, we and others reported that H3K27M DIPG cells exhibit elevated levels of another chromatin-associated histone posttranslational modification, demethylated lysine-36 of histone H3 (H3K36me2) (14)(15)(16). While H3K36me2 is antagonistic to the catalysis of H3K27me2/me3 (17,18), it remains unclear as to whether the elevated levels of H3K36me2 in DIPG arise through the increased levels of transcription in these cells or letup from the antagonistic effects of H3K27me2/me3.…”

WDR82 mediated H3K4me3 is associated with tumor proliferation and therapeutic efficacy in pediatric high-grade gliomas

“…Recently, H3K36me2 and H4K16Ac were discovered to be novel epigenetic signatures of DIPG (57). H3K4me3, an important histone mark for developmental neurogenesis, was relatively unaffected regardless of these mutations as shown with western blot analysis (14)(15)(16)(17).…”

“…These mutations crosstalk with other histone modifications and bring about abnormal gene expression involved in pediatric malignant glioma tumorigenesis. Recently, H3K36me2 and H4K16Ac were discovered to be novel epigenetic signatures of DIPG (57). H3K4me3, an important histone mark for developmental neurogenesis, was relatively unaffected regardless of these mutations as shown with western blot analysis (14–17).…”

Mutant MEG3 Enhances the Activity of Telomerase by Increasing DNA Damage Repair in Human Liver Cancer Stem Cells

“…Sirtuin-1 (SIRT1) is a class-III histone deacetylase (HDAC), an NAD+-dependent enzyme deeply involved in gene regulation, genome stability maintenance, apoptosis, autophagy, senescence, proliferation, aging, and tumorigenesis (23). Sirt1 also appears to be important for the turnover of defective mitochondria by mitophagy (24).SIRT1 regulates macrophage selfrenewal (25) and regulates lipid metabolism, oxidative stress and in ammation in the liver (26).Furthermore,SIRT1 has recently garnered tremendous attention because of its various regulatory effects in several pathological conditions (27).In additional, ATGL promotes autophagy/lipophagy via SIRT1 to control hepatic lipid droplet catabolism(28).H4K16Ac acts as epigenetic signatures of diffuse intrinsic pontine glioma (29).Selective binding of the PHD6 nger of MLL4 to histone H4K16Ac links MLL4 and MOF (30).JMJD6 modulates DNA damage response through downregulating H4K16Ac independently of its enzymatic activity (31).Acetylation of hMOF modulates H4K16Ac to regulate DNA repair genes (32,33). Moreover, our results demonstrate mutant MEG3 enhances the expression of SETD2 dependent on H4K16Ac.…”