Dataset Information

Class I HDAC inhibition reduces DNA damage repair capacity of MYC-amplified medulloblastoma cells.

ABSTRACT:

Purpose

MYC-driven Group 3 medulloblastoma (MB) (subtype II) is a highly aggressive childhood brain tumor. Sensitivity of MYC-driven MB to class I histone deacetylase inhibitors (HDACi) has been previously demonstrated in vitro and in vivo. In this study we characterize the transcriptional effects of class I HDACi in MYC-driven MB and explore beneficial drug combinations.

Methods

MYC-amplified Group 3 MB cells (HD-MB03) were treated with class I HDACi entinostat. Changes in the gene expression profile were quantified on a microarray. Bioinformatic assessment led to the identification of pathways affected by entinostat treatment. Five drugs interfering with these pathways (olaparib, idasanutlin, ribociclib, selinexor, vinblastine) were tested for synergy with entinostat in WST-8 metabolic activity assays in a 5 × 5 combination matrix design. Synergy was validated in cell count and flow cytometry experiments. The effect of entinostat and olaparib on DNA damage was evaluated by γH2A.X quantification in immunoblotting, fluorescence microscopy and flow cytometry.

Results

Entinostat treatment changed the expression of genes involved in 22 pathways, including downregulation of DNA damage response. The PARP1 inhibitors olaparib and pamiparib showed synergy with entinostat selectively in MYC-amplified MB cells, leading to increased cell death, decreased viability and increased formation of double strand breaks, as well as increased sensitivity to additional induction of DNA damage by doxorubicin. Non-MYC-amplified MB cells and normal human fibroblasts were not susceptible to this triple treatment.

Conclusion

Our study identifies the combination of entinostat with olaparib as a new potential therapeutic approach for MYC-driven Group 3 MB.

SUBMITTER: Vollmer J

PROVIDER: S-EPMC10589189 | biostudies-literature | 2023 Sep

REPOSITORIES: biostudies-literature

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Publications

Class I HDAC inhibition reduces DNA damage repair capacity of MYC-amplified medulloblastoma cells.

Vollmer Johanna J Ecker Jonas J Hielscher Thomas T Valinciute Gintvile G Ridinger Johannes J Jamaladdin Nora N Peterziel Heike H van Tilburg Cornelis M CM Oehme Ina I Witt Olaf O Milde Till T

Journal of neuro-oncology 20230901 3

<h4>Purpose</h4>MYC-driven Group 3 medulloblastoma (MB) (subtype II) is a highly aggressive childhood brain tumor. Sensitivity of MYC-driven MB to class I histone deacetylase inhibitors (HDACi) has been previously demonstrated in vitro and in vivo. In this study we characterize the transcriptional effects of class I HDACi in MYC-driven MB and explore beneficial drug combinations.<h4>Methods</h4>MYC-amplified Group 3 MB cells (HD-MB03) were treated with class I HDACi entinostat. Changes in the ge ...[more]

PMID: 37783879

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Project description:MYC-driven Group 3 medulloblastoma (MB) (subtype II) is a highly aggressive childhood brain tumor. Sensitivity of MYC-driven MBs to class I histone deacetylase inhibitors (HDACi) has been previously demonstrated in vitro and in vivo. We here characterize the transcriptional effects of class I HDAC inhibition in MYC-driven MB and explore beneficial drug combinations. MYC-amplified Group 3 MB cells (HD-MB03) were treated with class I HDACi entinostat. Changes in the gene expression profile compared to untreated control were quantified on a microarray. Gene set enrichment analysis, cytoscape enrichment mapping and ingenuity pathway analysis led to the identification of pathways affected by entinostat treatment. Five drugs interfering with these pathways (olaparib, idasanutlin, ribociclib, selinexor, vinblastine) were tested as single agents in metabolic activity assays in three MYC-amplified and two non-MYC-amplified MB cell lines. Synergy with entinostat was evaluated by dose response curve shift, combination index and zero interaction potency synergy model and validated in cell count and flow cytometry experiments in two MYC-amplified and one non-MYC-amplified MB cell line. The effect of the most promising drug combination (entinostat and olaparib) on DNA damage was evaluated by γH2A.X quantification in immunoblotting, fluorescence microscopy and flow cytometry. Entinostat treatment changed the expression of genes involved in 22 pathways, including downregulation of DNA damage response. The PARP1 inhibitors olaparib and pamiparib showed synergy with entinostat. The combination of entinostat and olaparib led to increased cell death, decreased viability and increased formation of double strand breaks selectively in MYC-amplified MB cells. MYC-amplified MB cells treated with entinostat and olaparib were particularly vulnerable to additional induction of DNA damage by doxorubicin. Non-MYC-amplified MB cells and normal human fibroblasts were not susceptible to this triple treatment. Our study identifies the combination of entinostat with olaparib and doxorubicin as a new potential therapeutic approach for MYC-driven Group 3 MB.

Project description:Medulloblastoma (MB) is the most common malignant pediatric brain tumor that can be categorized into four major molecular subgroups. Group 3 MB with MYC amplification (MYCamp-G3-MB) has been shown to be highly aggressive and exhibited worst prognosis, indicating the need for novel effective therapy most urgently. A few epigenetic targeted therapeutic strategies have recently been proven to effectively treat preclinical models of MYCamp-G3-MB, including BET inhibition, HDAC inhibition and SETD8 inhibition, unveiling a promising direction for further investigation. In this study, we carried out systemic bioinformatic analyses of public-available MB datasets as well as functional genomic screening datasets of primary MYCamp-G3-MB lines to search for other potential therapeutic targets within epigenetic modulators. We identified SSRP1, a subunit of histone-chaperone FACT complex, to be the top drug target candidate as it is highly cancer-dependent in whole-genome CRISPR-Cas9 screening across multiple MYCamp-G3-MB lines; significantly upregulated in MYCamp-G3-MB compared to normal cerebellum and most of the rest MB subtypes; its higher expression is correlated with worse prognosis; and it has a blood-brain-barrier penetrable targeted drug that has entered early phase human clinical trials already. Then we utilized RNA-interference approach to verify the cancer-dependency of SSRP1 in multiple MYCamp-G3-MB lines and further confirmed the therapeutic efficacy of FACT-targeted curaxin drug CBL0137 on treating preclinical models of MYCamp-G3-MB in vitro and in vivo, including an orthotopic intracranial xenograft model. Mechanistically, transcriptome analyses showed CBL0137 preferentially suppressed cell-cycle and DNA-repair related biological processes. Moreover, it selectively disrupted transcription of MYC and NEUROD1, two critical oncogenic transcription factors of MYCamp-G3-MB, via depleting FACT complex from their promoter regions. In summary, our study demonstrates FACT-targeted CBL0137 works effectively on treating MYCamp-G3-MB, presenting another promising epigenetic-targeted therapeutic strategy against the most devastating form of MB.

Dataset Information

Class I HDAC inhibition reduces DNA damage repair capacity of MYC-amplified medulloblastoma cells.

Purpose

Methods

Results

Conclusion

Publications

Class I HDAC inhibition reduces DNA damage repair capacity of MYC-amplified medulloblastoma cells.

Similar Datasets

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