Histone deacetylase inhibitors induce medulloblastoma cell death independent of HDACs recruited in REST repression complexes.

Abdulelah S Alshawli,Heiko Wurdak,Ian C Wood,John E Ladbury

doi:10.1002/mgg3.1429

Abdulelah S Alshawli, Heiko Wurdak + Show 2 more

Open Access

https://doi.org/10.1002/mgg3.1429

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Journal: Molecular Genetics & Genomic Medicine	Publication Date: Jul 27, 2020
Citations: 5	License type: CC BY 4.0

Affiliation: University of Leeds

Abstract

BackgroundRepressor element 1‐silencing transcription factor (REST) acts as a transcriptional repressor by recruiting several chromatin modifiers, including histone deacetylase (HDAC). Elevated REST expression in medulloblastoma has been associated with tumor progression nevertheless, the tumor shows high sensitivity to HDAC inhibitors (HDACi). However, the functional implications of REST and its requirement for HDACi‐induced anti‐cancer effects are not well understood.MethodsIn this study, the expression of REST was evaluated across the medulloblastoma subgroups and subtypes using published gene expression data. Further, the expression of REST was modulated using the CRISPR/Cas9 knockout and shRNA knockdown in the Daoy medulloblastoma cell line.ResultsThe results of this study showed that the expression of REST is elevated in most medulloblastoma subgroups compared to the non‐cancerous cerebellum. Blocking of REST expression resulted in increasing the expression of REST‐regulated genes, a moderate decrease in the fraction of the cells in the S‐phase, and reducing the cells' migration ability. However, REST deficiency did not lead to a marked decrease in the Daoy cell viability and sensitivity to HDACi.ConclusionThe findings of this study indicate that REST is not essential for sustaining the proliferation/viability of the Daoy cells. It also revealed that the anti‐proliferative effect of HDACi is independent of REST expression.

Highlights

Medulloblastoma is a diverse group of cerebellar tumors initiated from poorly differentiated neuroectodermal stem cells and characterized by the involvement of the genetic and epigenetic alterations in tumor development and treatment response (Aguilera et al, 2009; Hooper, Hawes, Kees, Gottardo, & Dallas, 2014)
Our results showed that Repressor element 1-silencing transcription factor (REST) expression was neither critically required for Daoy proliferation, nor for Histone deacetylases (HDACs) inhibitors (HDACi)-induced anti-proliferation effects, suggesting that the HDACi-anticancer mechanism is independent of REST expression in the Daoy cells
The results indicate that the downregulation of REST expression did not significantly reduce the sensitivity of the cells to the inhibitors (p < 0.0001) as the Daoy wildtype, KO & KD cells and their control counterparts displayed a similar response to HDACi (Figure 5)

Summary

| INTRODUCTION

Medulloblastoma is a diverse group of cerebellar tumors initiated from poorly differentiated neuroectodermal stem cells and characterized by the involvement of the genetic and epigenetic alterations in tumor development and treatment response (Aguilera et al, 2009; Hooper, Hawes, Kees, Gottardo, & Dallas, 2014). Gene expression and DNA-methylation profiling of medulloblastoma tumors revealed a significant heterogeneity within these subgroups, which resulted in further stratification of the medulloblastoma tumors into 12 different subtypes (known as WNTα and β, SHHα, β, γ and δ, Group 3α, β and γ, and Group 4α, β and γ) (Hovestadt et al, 2019) These subtypes are characterized by the activation of different molecular pathways and display different clinical outcomes ranging from favorable to poor prognosis (Cavalli et al, 2017). When REST binds to an RE1 site both its N-terminal and C-terminal domains work as hubs to recruit various chromatin remodeling and histone-modifying enzymes These include SIN3 transcription regulator family member A (SIN3A), REST corepressor 1 (RCOR1), SWI/SNF-related, matrix-associated actin-dependent regulator of chromatin subfamily a member 4 (SMARCA4), HDAC1, HDAC2, HDAC4, HDAC5, lysine demethylase 1A (KDM1A), and synaptonemal complex protein 1 (SYCP1) (Barrios et al, 2014; Ooi & Wood, 2008). Our results showed that REST expression was neither critically required for Daoy proliferation, nor for HDACi-induced anti-proliferation effects, suggesting that the HDACi-anticancer mechanism is independent of REST expression in the Daoy cells

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| DISCUSSION

Findings

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