The effect of methylation on the let-7-BCL2L1-BCL2 axis and the potential use of hypomethylating and BH3 mimetic drugs in histiocytic neoplasms
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ABSTRACT:
PROVIDER: PRJNA1170180 | ENA |
REPOSITORIES: ENA
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Project description:The histiocytoses [Erdheim-Chester Disease (ECD), Langerhans cell histiocytosis (LCH), and Rosai-Dorfman-Destombes disease (RDD)] are characterized by the infiltration of monocytes, macrophages, and dendritic cells in normal tissues, leading to significant morbidity due to disruption of critical organ systems. While their pathogenesis involves MAPK-ERK pathway mutations, their epigenetic landscape remains poorly understood. Epigenetic mechanisms such as DNA methylation, histone modification, and non-coding RNA are crucial in gene expression regulation and cancer development. We previously identified a distinct non-coding RNA profile in histiocytosis patients compared to controls. We analyzed the DNA methylation profile of 30 patients and found significant alterations in 23,322 methylation sites compared to controls, independent of age, gender, mutation type, or disease site. We observed a significant hypermethylation in the let-7b transcript, resulting in decreased let-7b expression. This led to the lack of regulation on the anti-apoptotic proteins BCL2L1, which was overexpressed in 21/21 (100%) patients' biopsies and BCL2 in 11/21 biopsies (52%). Treatment with the hypomethylating agent, 5-Azacytidine, restored let-7b expression, reduced BCL2L1 levels, and induced apoptosis in BRAFV600E mutant cells. Additionally, BCL2L1 and BCL2 inhibitors also induced apoptosis. This novel epigenetic mechanism suggests that hypomethylating agents or BH3 mimetic drugs may offer new therapeutic targets for histiocytosis.
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Project description:BH3 mimetics are used as an efficient strategy to promote mitochondrial-dependent cell death in blood malignancies, including acute myeloid leukemia (AML). Venetoclax, a potent BCL2 antagonist, is used clinically in combination with hypomethylating agents for the treatment of AML, while various compounds targeting MCL1 are in clinical trials. Yet, drug resistance eventually ensues, highlighting the urgency to understand the underlying mechanisms. Our genome-wide CRISPR/Cas9 screens revealed that loss of mitophagy regulators sensitizes AML to BH3 mimetics. One such regulator is Mitofusin-2 (MFN2), a GTPase that controls mitochondrial dynamics and the degradation of damaged mitochondria through mitophagy. Resistance to BH3 mimetics is accompanied by alterations in mitochondrial morphology, enhanced mitochondria-endoplasmic reticulum interactions, and augmented mitophagy flux. MFN2 inactivation, using a novel small molecule inhibitor, and pharmacologic inhibition of mitophagy synergizes with BH3 mimetics. Overall, targeting of mitophagy along with BCL2-family members is a promising strategy to overcome drug resistance in AML.
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Project description:This SuperSeries is composed of the SubSeries listed below. The translocation t(11;14) occurs in 20% of multiple myeloma (MM) patients and results in the upregulation of CCND1. Nearly two-thirds of t(11;14) MM cells are BCL2 primed and highly responsive to the oral BCL2 inhibitor venetoclax. While it is evident that this unique sensitivity to venetoclax depends on the BH3-proapoptotic protein priming of BCL2, the biology underlying t(11;14) MM dependency on BCL2 is poorly defined. Importantly, the epigenetic regulation of t(11;14) transcriptomes and its impact on gene regulation and clinical response to venetoclax remains elusive. In this study, by integrating ATACseq and RNAseq at the single-cell level in primary MM samples, we have defined the epigenetic regulome and transcriptome associated with t(11;14) MM. A "B cell-like" epigenetic signature was enriched in t(11;14) MM, confirming its phylogeny link to B cell rather than plasma cell biology. Of note, a loss of a "B cell-like" epigenetic signature with a gain of canonical plasma cell transcription factors was observed at the time of resistance to venetoclax. In addition, MCL1 and BCL2L1 copy number gains and structural rearrangements were linked to venetoclax resistance in t(11;14) MM patients. To date, this is the first study in which both scATAC-seq and scRNA-seq analysis are integrated into primary MM cells to obtain a deeper resolution of the epigenetic regulome and transcriptome associated with t(11;14) MM biology and venetoclax resistance.
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Project description:The translocation t(11;14) occurs in 20% of multiple myeloma (MM) patients and results in the upregulation of CCND1. Nearly two-thirds of t(11;14) MM cells are BCL2 primed and highly responsive to the oral BCL2 inhibitor venetoclax. While it is evident that this unique sensitivity to venetoclax depends on the BH3-proapoptotic protein priming of BCL2, the biology underlying t(11;14) MM dependency on BCL2 is poorly defined. Importantly, the epigenetic regulation of t(11;14) transcriptomes and its impact on gene regulation and clinical response to venetoclax remains elusive. In this study, by integrating ATACseq and RNAseq at the single-cell level in primary MM samples, we have defined the epigenetic regulome and transcriptome associated with t(11;14) MM. A "B cell-like" epigenetic signature was enriched in t(11;14) MM, confirming its phylogeny link to B cell rather than plasma cell biology. Of note, a loss of a "B cell-like" epigenetic signature with a gain of canonical plasma cell transcription factors was observed at the time of resistance to venetoclax. In addition, MCL1 and BCL2L1 copy number gains and structural rearrangements were linked to venetoclax resistance in t(11;14) MM patients. To date, this is the first study in which both scATAC-seq and scRNA-seq analysis are integrated into primary MM cells to obtain a deeper resolution of the epigenetic regulome and transcriptome associated with t(11;14) MM biology and venetoclax resistance.
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Project description:The translocation t(11;14) occurs in 20% of multiple myeloma (MM) patients and results in the upregulation of CCND1. Nearly two-thirds of t(11;14) MM cells are BCL2 primed and highly responsive to the oral BCL2 inhibitor venetoclax. While it is evident that this unique sensitivity to venetoclax depends on the BH3-proapoptotic protein priming of BCL2, the biology underlying t(11;14) MM dependency on BCL2 is poorly defined. Importantly, the epigenetic regulation of t(11;14) transcriptomes and its impact on gene regulation and clinical response to venetoclax remains elusive. In this study, by integrating ATACseq and RNAseq at the single-cell level in primary MM samples, we have defined the epigenetic regulome and transcriptome associated with t(11;14) MM. A "B cell-like" epigenetic signature was enriched in t(11;14) MM, confirming its phylogeny link to B cell rather than plasma cell biology. Of note, a loss of a "B cell-like" epigenetic signature with a gain of canonical plasma cell transcription factors was observed at the time of resistance to venetoclax. In addition, MCL1 and BCL2L1 copy number gains and structural rearrangements were linked to venetoclax resistance in t(11;14) MM patients. To date, this is the first study in which both scATAC-seq and scRNA-seq analysis are integrated into primary MM cells to obtain a deeper resolution of the epigenetic regulome and transcriptome associated with t(11;14) MM biology and venetoclax resistance.
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Project description:The translocation t(11;14) occurs in 20% of multiple myeloma (MM) patients and results in the upregulation of CCND1. Nearly two-thirds of t(11;14) MM cells are BCL2 primed and highly responsive to the oral BCL2 inhibitor venetoclax. While it is evident that this unique sensitivity to venetoclax depends on the BH3-proapoptotic protein priming of BCL2, the biology underlying t(11;14) MM dependency on BCL2 is poorly defined. Importantly, the epigenetic regulation of t(11;14) transcriptomes and its impact on gene regulation and clinical response to venetoclax remains elusive. In this study, by integrating ATACseq and RNAseq at the single-cell level in primary MM samples, we have defined the epigenetic regulome and transcriptome associated with t(11;14) MM. A "B cell-like" epigenetic signature was enriched in t(11;14) MM, confirming its phylogeny link to B cell rather than plasma cell biology. Of note, a loss of a "B cell-like" epigenetic signature with a gain of canonical plasma cell transcription factors was observed at the time of resistance to venetoclax. In addition, MCL1 and BCL2L1 copy number gains and structural rearrangements were linked to venetoclax resistance in t(11;14) MM patients. To date, this is the first study in which both scATAC-seq and scRNA-seq analysis are integrated into primary MM cells to obtain a deeper resolution of the epigenetic regulome and transcriptome associated with t(11;14) MM biology and venetoclax resistance.
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