Novel Insights Into Epigenetic Reprogramming and Destabilization of Pericentromeric Heterochromatin in Cancer

The use of human dental pulp stromal cells (hDPSCs) has gained increasing attention as an alternative stem cell source for bone tissue engineering. The modification of the cells’ epigenetics has been found to play an important role in regulating differentiation, with the inhibition of histone deacetylases 3 (HDAC3) being linked to increased osteogenic differentiation. This study aimed to induce epigenetic reprogramming using the HDAC2 and 3 selective inhibitor, MI192 to promote hDPSCs osteogenic capacity for bone regeneration. MI192 treatment caused a time–dose-dependent change in hDPSC morphology and reduction in viability. Additionally, MI192 successfully augmented hDPSC epigenetic functionality, which resulted in increased histone acetylation and cell cycle arrest at the G2/M phase. MI192 pre-treatment exhibited a dose-dependent effect on hDPSCs alkaline phosphatase activity. Quantitative PCR and In-Cell Western further demonstrated that MI192 pre-treatment significantly upregulated hDPSCs osteoblast-related gene and protein expression (alkaline phosphatase, bone morphogenic protein 2, type I collagen and osteocalcin) during osteogenic differentiation. Importantly, MI192 pre-treatment significantly increased hDPSCs extracellular matrix collagen production and mineralisation. As such, for the first time, our findings show that epigenetic reprogramming with the HDAC2 and 3 selective inhibitor MI192 accelerates the osteogenic differentiation of hDPSCs, demonstrating the considerable utility of this MSCs engineering approach for bone augmentation strategies.

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SAVER: sodium valproate for the epigenetic reprogramming of high-risk oral epithelial dysplasia—a phase II randomised control trial study protocol

Trials ◽

10.1186/s13063-021-05373-8 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Caroline McCarthy ◽

Joseph Sacco ◽

Stefano Fedele ◽

Michael Ho ◽

Stephen Porter ◽

...

Keyword(s):

High Risk ◽

Sodium Valproate ◽

Study Protocol ◽

Epigenetic Reprogramming ◽

Epithelial Dysplasia ◽

Phase Iii ◽

Cancer Development ◽

Randomised Control Trial ◽

Oral Epithelial Dysplasia ◽

Oral Epithelial

Abstract Background Sodium valproate (VPA) has been associated with a reduced risk of head and neck cancer development. The potential protective mechanism of action is believed to be via inhibition of histone deacetylase and subsequent epigenetic reprogramming. SAVER is a phase IIb open-label, randomised control trial of VPA as a chemopreventive agent in patients with high-risk oral epithelial dysplasia (OED). The aim of the trial is to gather preliminary evidence of the clinical and biological effects of VPA upon OED and assess the feasibility and acceptability of such a trial, with a view to inform a future definitive phase III study. Methods One hundred and ten patients with high-risk OED will be recruited from up to 10 secondary care sites in the UK and randomised into either VPA or observation only for 4 months. Women of childbearing potential will be excluded due to the teratogenic properties of VPA. Tissue and blood samples will be collected prior to randomisation and on the last day of the intervention/observation-only period (end of 4 months). Clinical measurement and additional safety bloods will be taken at multiple time points during the trial. The primary outcome will be a composite, surrogate endpoint of change in lesion size, change in grade of dysplasia and change in LOH profile at 8 key microsatellite regions. Feasibility outcomes will include recruitment targets, compliance with the study protocol and adverse effects. A qualitative sub-study will explore patient experience and perception of the trial. Discussion The current management options for patients with high-risk OED are limited and mostly include surgical resection and clinical surveillance. However, there remains little evidence whether surgery can effectively lead to a notable reduction in the risk of oral cancer development. Similarly, surveillance is associated with concerns regarding delayed diagnosis of OED progressing to malignancy. The SAVER trial provides an opportunity to investigate the effects of a repurposed, inexpensive and well-tolerated medication as a potential chemopreventive strategy for patients with high-risk OED. The clinical and biological findings of SAVER will inform the appropriateness, design and feasibility of a definitive phase III trial. Trial registration The trial is registered with the European Clinical Trials Database (Eudra-CT 2018-000197-30). (http://www.isrctn.com/ISRCTN12448611). The trial was prospectively registered on 24/04/2018.

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Chromatin assembly factor 1 suppresses epigenetic reprogramming toward adaptive drug resistance

Journal of the National Cancer Center ◽

10.1016/j.jncc.2020.12.003 ◽

2021 ◽

Author(s):

Zhiquan Wang ◽

Rentian Wu ◽

Qian Nie ◽

Kelly J. Bouchonville ◽

Robert B. Diasio ◽

...

Keyword(s):

Drug Resistance ◽

Epigenetic Reprogramming ◽

Chromatin Assembly ◽

Chromatin Assembly Factor ◽

Assembly Factor

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CBIO-16. SUPPRESSION OF HISTONE H3.3 MITOTIC PHOSPHORYLATION DRIVES DEVELOPMENT OF H3K27M-MUTANT DIFFUSE MIDLINE GLIOMAS

Neuro-Oncology ◽

10.1093/neuonc/noaa215.076 ◽

2020 ◽

Vol 22 (Supplement_2) ◽

pp. ii18-ii19

Author(s):

Charles Day ◽

Alyssa Langfald ◽

Florina Grigore ◽

Leslie Sepaniac ◽

Jason Stumpff ◽

...

Keyword(s):

Chromosome Segregation ◽

Treatment Options ◽

Chromosome Instability ◽

Pericentromeric Heterochromatin ◽

Low Grade ◽

High Grade ◽

Chromosome Missegregation ◽

Mitotic Phosphorylation ◽

Chk1 Kinase

Abstract Pediatric midline gliomas – including DIPG – are lethal brain tumors in children, with poor prognosis and limited treatment options that provide only short-term benefits. The majority have a lysine-to-methionine substitution at residue 27 (H3K27M) in genes expressing histone H3 – predominantly in the H3.3 variant. This causes a global reduction in H3 Lys27 tri-methylation (H3K27Me3), comprehensive epigenetic reprogramming, and is a key driver in gliomagenesis. We show that the H3.3K27M mutation also induces chromosome segregation defects, which in high-grade tumors, results in extensive copy number alterations (CNAs). Ser31 is one of five amino acid substitutions differentiating H3.3 from canonical H3.1. Mitotic phosphorylation of H3.3 Ser31 by Chk1 kinase is restricted to pericentromeric heterochromatin, where it plays a role in chromosome segregation. We show that the K27M mutation affects neighboring Ser31 phosphorylation and pericentromeric heterochromatin organization. We demonstrate that (i) H3.3 K27M protein is defective for Ser31 phosphorylation by Chk1 kinase in vitro; (ii) DIPG cell lines have significantly decreased mitotic Ser31 phosphorylation, and are chromosomally unstable; and (iii) CRISPR-reversion of H3.3K27M to Lys27 restores phospho-Ser31 (and Lys27 tri-methylation) and significantly decreases chromosome instability. Expression of H3.3K27M or non-phosphorylatable H3.3S31A mutants in WT cells results in chromosome missegregation; this is suppressed by co-expression of phospho-mimetic H3.3K27M/S31E. In normal cells, chromosome missegregation stimulates p53-dependent cell cycle arrest in G1 to prevent the proliferation of aneuploid daughters. However, cells expressing H3.3 K27M or S31A failed to arrest following missegregation - despite having WT p53. Finally, in a novel mouse model of glioma, mean survival of mice with tumors induced with H3.3K27M and H3.3S31A was 81 and 68 days: 100% of H3.3S31A mice developed high-grade tumors. H3.3 WT controls developed only low-grade tumors and all survived 100 days. H3.3S31A is WT for Lys27 tri-methylation and thus, loss of Ser31 phosphorylation alone is oncogenic.

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