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- Öberg, Fredrik, et al.
(författare)
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Herbal melanin activates TLR4/NF-kappaB signaling pathway
- 2009
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Ingår i: Phytomedicine. - : Elsevier BV. - 0944-7113 .- 1618-095X. ; 16:5, s. 477-84
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Tidskriftsartikel (refereegranskat)abstract
- Expression of many pro-inflammatory cytokines is controlled by the NF-kappaB signaling pathway. NF-kappaB is induced by LPS through activation of TLR4. Melanins extracted from fungal, plant and human sources modulate cytokine production and activate NF-kappaB pathway. We showed that a herbal melanin (HM) from Nigella sativa L. modulates cytokine production and suggested it as a ligand for TLR4. In this study we investigated the possibility that the HM-induced cytokine production is via an NF-kappaB signaling pathway. We found that HM induced the degradation of IkappaBalpha, a key step in the activation of NF-kappaB. Moreover, addition of IkappaB kinase (IKK) specific inhibitors effectively inhibited the observed HM-induced production of IL-8 and IL-6 by TLR4-transfected HEK293 cells and THP-1 cells. Our results have also shown that HM induced cleavage of caspase 8, and that this cleavage was partially abrogated by IKK inhibitors. We suggest that HM can modulate the inflammatory response by inducing IL-8 and IL-6 production via TLR4-dependent activation of the NF-kappaB signaling pathway.
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- 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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- 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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- 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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- 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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- 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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