| 1. |
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| 2. |
- Agarwal, Prasoon, et al.
(författare)
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Genome-wide profiling of histone H3 lysine 27 and lysine 4 trimethylation in multiple myeloma reveals the importance of Polycomb gene targeting and highlights EZH2 as a potential therapeutic target.
- 2016
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Ingår i: Oncotarget. - : Impact Journals, LLC. - 1949-2553. ; 7:6, s. 6809-6923
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Tidskriftsartikel (refereegranskat)abstract
- Multiple myeloma (MM) is a malignancy of the antibody-producing plasma cells. MM is a highly heterogeneous disease, which has hampered the identification of a common underlying mechanism for disease establishment as well as the development of targeted therapy. Here we present the first genome-wide profiling of histone H3 lysine 27 and lysine 4 trimethylation in MM patient samples, defining a common set of active H3K4me3-enriched genes and silent genes marked by H3K27me3 (H3K27me3 alone or bivalent) unique to primary MM cells, when compared to normal bone marrow plasma cells. Using this epigenome profile, we found increased silencing of H3K27me3 targets in MM patients at advanced stages of the disease, and the expression pattern of H3K27me3-marked genes correlated with poor patient survival. We also demonstrated that pharmacological inhibition of EZH2 had anti-myeloma effects in both MM cell lines and CD138+ MM patient cells. In addition, EZH2 inhibition decreased the global H3K27 methylation and induced apoptosis. Taken together, these data suggest an important role for the Polycomb repressive complex 2 (PRC2) in MM, and highlights the PRC2 component EZH2 as a potential therapeutic target in MM.
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| 3. |
- Agarwal, Prasoon, et al.
(författare)
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The epigenomic map of multiple myeloma reveals the importance of Polycomb gene silencing for the malignancy
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Multiple myeloma (MM) is characterized by accumulation of post-germinal center, isotype switched, long-living plasma cells with retained proliferation capacity within the bone marrow. MM is highly heterogeneous and remains fatal. This heterogeneity has hampered identification of a common underlying mechanism for disease establishment and the development of targeted therapy. We recently provided proof-of-principle that gene silencing associated with H3K27me3 contributes to the malignancy of MM. Here we present the first epigenomic map of MM for H3K27me3 and H3K4me3 derived by ChIP- and RNA sequencing from freshly-isolated bone marrow plasma cells from four patients. We compile lists of targets common among the patients as well as unique to MM when compared with PBMCs. Indicating the clinical relevance of our findings, we find increased silencing of H3K27me3 targets with disease progression and in patients presenting with a poor prognosis. Bivalent genes further significantly correlated to under-expressed genes in MM and were unique to MM when compared to PBMCs. Furthermore, bivalent genes, unlike H3K27me3 targets, significantly associated with transcriptional activation upon Polycomb inhibition indicating a potential for drug targeting. Thus, we suggest that gene silencing by Polycomb plays an important role in the development of the malignant phenotype of the MM cell during tumor progression.
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| 4. |
- Alzrigat, Mohammad, et al.
(författare)
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EZH2 inhibition in multiple myeloma downregulates myeloma associated oncogenes and upregulates microRNAs with potential tumor suppressor functions.
- 2017
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Ingår i: Oncotarget. - : Impact Journals, LLC. - 1949-2553. ; 8:6, s. 10213-10224
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Tidskriftsartikel (refereegranskat)abstract
- Multiple Myeloma (MM) is a plasma cell tumor localized to the bone marrow (BM). Despite the fact that current treatment strategies have improved patients' median survival time, MM remains incurable. Epigenetic aberrations are emerging as important players in tumorigenesis making them attractive targets for therapy in cancer including MM. Recently, we suggested the polycomb repressive complex 2 (PRC2) as a common denominator of gene silencing in MM and presented the PRC2 enzymatic subunit enhancer of zeste homolog 2 (EZH2) as a potential therapeutic target in MM. Here we further dissect the anti-myeloma mechanisms mediated by EZH2 inhibition and show that pharmacological inhibition of EZH2 reduces the expression of MM-associated oncogenes; IRF-4, XBP-1, PRDM1/BLIMP-1 and c-MYC. We show that EZH2 inhibition reactivates the expression of microRNAs with tumor suppressor functions predicted to target MM-associated oncogenes; primarily miR-125a-3p and miR-320c. ChIP analysis reveals that miR-125a-3p and miR-320c are targets of EZH2 and H3K27me3 in MM cell lines and primary cells. Our results further highlight that polycomb-mediated silencing in MM includes microRNAs with tumor suppressor activity. This novel role strengthens the oncogenic features of EZH2 and its potential as a therapeutic target in MM.
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| 5. |
- Alzrigat, Mohammad
(författare)
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Targeted Inhibition of Polycomb Repressive Complexes in Multiple Myeloma : Implications for Biology and Therapy
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Multiple myeloma (MM) is a hematological malignancy of antibody producing plasmablasts/plasma cells. MM is characterized by extensive genetic and clonal heterogeneity, which have hampered the attempts to identify a common underlying mechanism for disease establishment and development of appropriate treatment regimes. This thesis is focused on understanding the role of epigenetic regulation of gene expression mediated by the polycomb repressive complexes 1 and 2 (PRC1 and 2) in MM and their impact on disease biology and therapy.In paper I the genome-wide distribution of two histone methylation marks; H3K27me3 and H3K4me3 were studied in plasma cells isolated from newly diagnosed MM patients or age-matched normal donors. We were able to define targets of H3K27me3, H3K4me3 and bivalent (carry both marks) which are, when compared to normal individuals, unique to MM patients. The presence of H3K27me3 correlated with silencing of MM unique H3K27me3 targets in MM patients at advanced stages of the disease. Notably, the expression pattern of H3K27me3-marked genes correlated with poor patient survival. We also showed that inhibition of the PRC2 enzymatic subunit EZH2 using highly selective inhibitors (GSK343 and UNC1999) demonstrated anti-myeloma activity using relevant in vitro models of MM. These data suggest an important role for gene repression mediated by PRC2 in MM, and highlights the PRC2 component EZH2 as a potential therapeutic target in MM.In paper II we further explored the therapeutic potential of UNC1999, a highly selective inhibitor of EZH2 in MM. We showed that EZH2 inhibition by UNC1999 downregulated important MM oncogenes; IRF-4, XBP-1, BLIMP-1and c-MYC. These oncogenes have been previously shown to be crucial for disease establishment, growth and progression. We found that EZH2 inhibition reactivated the expression of microRNAs genes previously found to be underexpressed in MM and which possess potential tumor suppressor functions. Among the reactivated microRNAs we identified miR-125a-3p and miR-320c as predicted negative regulators of the MM-associated oncogenes. Notably, we defined miR-125a-3p and miR-320c as targets of EZH2 and H3K27me3 in MM cell lines and patients samples. These findings described for the first time PRC2/EZH2/H3K27me3 as regulators of microRNA with tumor suppressor functions in MM. This further strengthens the oncogenic features of EZH2 and its potential as a therapeutic target in MM.In paper III we evaluated the therapeutic potential of targeting PRC1 in MM using the recently developed chemical PTC-209; an inhibitor targeting the BMI-1 subunit of PRC1. Using MM cell lines and primary cells isolated from newly diagnosed or relapsed MM patients, we found that PTC-209 has a potent anti-MM activity. We showed, for the first time in MM, that PTC-209 anti-MM effects were mediated by on-target effects i.e. downregulation of BMI-1 protein and the associated repressive histone mark H2AK119ub, but that other subunits of the PRC1 complex were not affected. We showed that PTC-209 reduced MM cell viability via significant induction of apoptosis. More importantly, we demonstrated that PTC-209 shows synergistic anti-MM activity with other epigenetic inhibitors targeting EZH2 (UNC1999) and BET-bromodomains (JQ1). This work highlights the potential use of BMI-1 and PRC1 as potential therapeutic targets in MM alone or in combination with other anti-MM agents including epigenetic inhibitors.
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| 6. |
- Alzrigat, Mohammad, et al.
(författare)
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The polycomb group protein BMI-1 inhibitor PTC-209 is a potent anti-myeloma agent alone or in combination with epigenetic inhibitors targeting EZH2 and the BET bromodomain
- 2017
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Ingår i: Oncotarget. - : Impact Journals, LLC. - 1949-2553. ; 8:61, s. 103731-103743
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Tidskriftsartikel (refereegranskat)abstract
- Multiple myeloma (MM) is a tumor of plasmablasts/plasma cells (PCs) characterized by the expansion of malignant PCs with complex genetic aberrations in the bone marrow (BM). Recent reports, by us and others, have highlighted the polycomb group (PcG) proteins as potential targets for therapy in MM. The PcG protein BMI-1 of the polycomb repressive complex 1 (PRC1) has been reported to be overexpressed and to possess oncogenic functions in MM. Herein, we report on the anti-myeloma effects of the BMI-1 inhibitor PTC-209 and demonstrate that PTC-209 is a potent anti-myeloma agent in vitro using MM cell lines and primary MM cells. We show that PTC-209 reduces the viability of MM cells via induction of apoptosis and reveal that the anti-MM actions of PTC-209 are mediated by on-target effects i.e. downregulation of BMI-1 protein and the associated repressive histone mark H2AK119ub, leaving other PRC1 subunits such as CBX-7 and the catalytic subunit RING1B unaffected. Importantly, we demonstrate that PTC-209 exhibits synergistic and additive anti-myeloma activity when combined with other epigenetic inhibitors targeting EZH2 and BET bromodomains. Collectively, these data qualify BMI-1 as a candidate for targeted therapy in MM alone or in combinations with epigenetic inhibitors directed to PRC2/EZH2 or BET bromodomains.
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| 7. |
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| 8. |
- Atienza-Párraga, Alba, et al.
(författare)
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Epigenomic re-configuration of primary multiple myeloma underlies the synergistic effect of combined DNMT and EZH2 inhibition.
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Multiple myeloma (MM) is characterized by an overexpression of EZH2 and a subsequent increase in H3K27me3-mediated silencing. However, the genome-wide redistribution of this mark in context with other epigenetic tags remains largely unexplored. Here, we show that EZH2 physically interacts with DNMT1 and that combined inhibition leads to a reduced G2/M arrest and increased apoptosis in MM. In addition, we present a catalogue of the genomic regulatory regions in normal plasma cells (NPC) as defined by their individual combination of histone marks. We used ChIP-seq and ATAC-seq data to generate whole-genome NPC chromatin annotations which we further analysed using DNA methylation arrays and RNA-seq. Comparison between NPC and MM demonstrated that, despite the global hypomethylation, enhancers show a tendency towards a higher DNA methylation levels in MM, whereas Polycomb and heterochromatic sites, highly methylated in NPC, show intermediate levels of the mark. Across all examined regulatory regions, 5-azacytidine treatment strongly reduced DNA methylation in MM. Furthermore, we find an extensive re-structuration of the global histone patterns in MM. We noticed a widespread increase in H3K27me3 except at active TSSs/promoters and enhancers, where we found a selective gain of the mark, suggestive of a directed silencing. In contrast, poised TSSs lose H3K27me3 and gain the activation mark H3K27ac, reflecting potential activation. Taken together, we present a comprehensive map of the epigenomic changes in MM as compared to NPC and provide insights into the interplay between EZH2 and DNMT1 in MM.
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| 9. |
- Bolin, Sara, 1988-, et al.
(författare)
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Dormant SOX9-positive cells behind MYC-driven medulloblastoma recurrence
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Tidskriftsartikel (refereegranskat)abstract
- Tumor recurrence is a slow biological process involving therapy resistance, immune escape, and metastasis and is the leading cause of death in medulloblastoma, the most frequent malignant pediatric brain tumor. By studying paired primary-recurrent patient samples and patient-derived xenografts we identified a significant accumulation of SOX9-positive cells in relapses and metastases. They exist as rare, quiescent cells in Group 3 and Group 4 patients that constitute two-thirds of medulloblastoma. To follow relapse at the single-cell level we developed an inducible dual Tet model of MYC-driven MB, where MYC can be directed from treatment-sensitive bulk cells to resistant, dormant SOX9-positive cells by doxycycline. SOX9 promoted immune es-cape, DNA repair suppression and was essential for recurrence. Tumor cell dormancy was non-hierarchical, migratory, and depended on MYC suppression by SOX9 to promote relapse. By using computational modeling and treatment we further showed how doxorubicin and MGMT inhibitors are specifically targeting relapsing cells.
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| 10. |
- Borgenvik, Anna, 1987-, et al.
(författare)
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Dormant SOX9-Positive Cells Facilitate MYC-Driven Recurrence of Medulloblastoma
- 2022
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Ingår i: Cancer Research. - : AMER ASSOC CANCER RESEARCH. - 0008-5472 .- 1538-7445. ; 82:24, s. 4586-4603
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Tidskriftsartikel (refereegranskat)abstract
- Relapse is the leading cause of death in patients with medulloblas-toma, the most common malignant pediatric brain tumor. A better understanding of the mechanisms underlying recurrence could lead to more effective therapies for targeting tumor relapses. Here, we observed that SOX9, a transcription factor and stem cell/glial fate marker, is limited to rare, quiescent cells in high-risk medulloblastoma with MYC amplification. In paired primary-recurrent patient samples, SOX9-positive cells accumulated in medulloblastoma relapses. SOX9 expression anti-correlated with MYC expression in murine and human medulloblastoma cells. However, SOX9-positive cells were plastic and could give rise to a MYC high state. To follow relapse at the single-cell level, an inducible dual Tet model of medulloblastoma was developed, in which MYC expression was redirected in vivo from treatment-sensitive bulk cells to dormant SOX9-positive cells using doxycycline treatment. SOX9 was essential for relapse initiation and depended on suppression of MYC activity to promote therapy resistance, epithelial-mesenchymal transition, and immune escape. p53 and DNA repair pathways were downregulated in recurrent tumors, whereas MGMT was upregulated. Recurrent tumor cells were found to be sensitive to treatment with an MGMT inhibitor and doxorubicin. These findings suggest that recurrence-specific targeting coupled with DNA repair inhibition comprises a potential therapeutic strategy in patients affected by medulloblastoma relapse.Significance: SOX9 facilitates therapy escape and recurrence in medulloblastoma via temporal inhibition of MYC/MYCN genes, revealing a strategy to specifically target SOX9-positive cells to prevent tumor relapse.
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