EZH2 deficient T-cell acute lymphoblastic leukemia is sensitized to CHK1 inhibition through enhanced replication stress
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA613316 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR11348490_1.fastq.gz | Fastqsanger.gz | |||
| SRR11348490_2.fastq.gz | Fastqsanger.gz | |||
| SRR11348491_1.fastq.gz | Fastqsanger.gz | |||
| SRR11348491_2.fastq.gz | Fastqsanger.gz |
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Project description:Loss-of-function mutations of EZH2, the enzymatic component of PRC2, are recurrently found in T-cell acute lymphoblastic leukemia (T-ALL) and have been associated with chemotherapy resistance and poor outcome. Using isogenic T-ALL cells, with and without CRISPR-induced EZH2-inactivating mutations, we performed a cell-based synthetic lethal drug screen. EZH2 deficient cells exhibited increased sensitivity to structurally diverse CHK1 inhibitors, an interaction that could be validated genetically. Notably, EZH2 deficient cells acquired a gene expression signature of immature T-ALL cells, with significant enrichment of MYC target genes. Mechanistically, EZH2 deficiency was associated with marked transcriptional upregulation of MYCN, increased replication stress, and enhanced dependency on CHK1 for cell survival. Furthermore, small molecule inhibition of CHK1 had efficacy in delaying tumor progression in isogenic EZH2 deficient, but not EZH2 wild-type T-ALL cells in vivo, suggesting there is an exploitable therapeutic window for CHK1 inhibitors in high risk EZH2 mutated T-ALL.
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Project description:Loss-of-function mutations of EZH2, the enzymatic component of PRC2, have been associated with poor outcome and chemotherapy resistance in T-cell acute lymphoblastic leukemia (T-ALL). Using isogenic T-ALL cells, with and without CRISPR/Cas9-induced EZH2-inactivating mutations, we performed a cell-based synthetic lethal drug screen. EZH2 deficient cells exhibited increased sensitivity to structurally diverse inhibitors of CHK1, an interaction that could be validated genetically. Furthermore, small molecule inhibition of CHK1 had efficacy in delaying tumor progression in isogenic EZH2 deficient, but not EZH2 wild-type T-ALL cells in vivo, as well as in a primary cell model of PRC2 mutant ALL. Mechanistically, EZH2 deficiency resulted in a gene expression signature of immature T-ALL cells, marked transcriptional upregulation of MYCN, increased replication stress, and enhanced dependency on CHK1 for cell survival. Lastly, we demonstrate this phenotype is mediated through de-repression of a distal PRC2-regulated MYCN enhancer. In conclusion, we highlight a novel and clinically exploitable pathway in high-risk EZH2 mutated T-ALL.
2020-05-31 | GSE147198 | GEO
Project description:EZH2 deficient T-cell acute lymphoblastic leukemia is sensitized to CHK1 inhibition through enhanced replication stress
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Project description:Loss-of-function mutations of EZH2, the enzymatic component of PRC2, have been associated with poor outcome and chemotherapy resistance in T-cell acute lymphoblastic leukemia (T-ALL). Using isogenic T-ALL cells, with and without CRISPR/Cas9-induced EZH2-inactivating mutations, we performed a cell-based synthetic lethal drug screen. EZH2-deficient cells exhibited increased sensitivity to structurally diverse inhibitors of CHK1, an interaction that could be validated genetically. Furthermore, small-molecule inhibition of CHK1 had efficacy in delaying tumor progression in isogenic EZH2-deficient, but not EZH2 wild-type, T-ALL cells in vivo, as well as in a primary cell model of PRC2-mutant ALL. Mechanistically, EZH2 deficiency resulted in a gene-expression signature of immature T-ALL cells, marked transcriptional upregulation of MYCN, increased replication stress, and enhanced dependency on CHK1 for cell survival. Finally, we demonstrate this phenotype is mediated through derepression of a distal PRC2-regulated MYCN enhancer. In conclusion, we highlight a novel and clinically exploitable pathway in high-risk EZH2-mutated T-ALL. SIGNIFICANCE: Loss-of-function mutations of PRC2 genes are associated with chemotherapy resistance in T-ALL, yet no specific therapy for this aggressive subtype is currently clinically available. Our work demonstrates that loss of EZH2 activity leads to MYCN-driven replication stress, resulting in increased sensitivity to CHK1 inhibition, a finding with immediate clinical relevance.This article is highlighted in the In This Issue feature, p. 890.
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Project description:While effective anti-cancer drugs targeting the CHK1 kinase are advancing in the clinic, drug resistance is rapidly emerging. Here, we demonstrate that CRISPR-mediated knockout of the little-known gene FAM122A confers cellular resistance to CHK1 inhibitors and cross-resistance to ATR inhibitors. Knockout of FAM122A results in activation of PP2A-B55α, a phosphatase which dephosphorylates the WEE1 protein and rescues WEE1 from Ubiquitin-mediated degradation. The resulting increase in WEE1 protein expression reduces replication stress, activates the G2/M checkpoint, and confers cellular resistance to CHK1 inhibitors. Interestingly, in tumor cells with oncogene-driven replication stress, CHK1 can directly phosphorylate FAM122A, leading to activation of the PP2A-B55α phosphatase and increased WEE1 expression. A combination of a CHK1 inhibitor plus a WEE1 inhibitor can overcome CHK1 inhibitor resistance of these tumor cells, thereby enhancing anti-cancer activity. The FAM122A expression level in a tumor cell can serve as a useful biomarker for predicting CHK1 inhibitor sensitivity or resistance.
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Project description:Establishment and differentiation of mammary alveoli during pregnancy are controlled by prolactin through the transcription factor STAT5. As pregnancy progresses mammary signature genes are activated in a defined temporal order, which coincides with the recruitment of STAT5 to respective regulatory sequences. This study addressed the question whether the methyltransferase and transcriptional co-activator EZH2 controls the differentiation clock of mammary epithelium. Ablation of Ezh2 from mammary stem cells resulted in precocious differentiation of alveolar epithelium and accelerated activation of mammary signature genes. This coincided with enhanced occupancy by EZH1, Pol II and STAT5 to mammary-specific loci. Notably, loss of EZH2 did not result in overt changes in genome-wide and gene-specific H3K27me3 patterns, suggesting that enhanced EZH1 recruitment can compensate for the loss of EZH2. However, differentiated mammary epithelia failed to form in the combined absence of EZH1 and EZH2. Transplantation experiments failed to demonstrate a role for EZH2 in the biology of mammary stem and progenitor cells. In summary, while EZH1 and EZH2 serve redundant functions in the establishment of H3K27me3 and formation of mammary alveoli, the presence of EZH2 is required to obtain controlled temporal differentiation of mammary epithelium.
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