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- Abdulkadir Ali, Hani
(författare)
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Exploring the role of epigenetic alterations in myeloid malignancies with focus on drug response
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The production of blood cells (hematopoiesis), where the hematopoietic stem cell (HSC) is the cell of origin of all blood cells, is regulated by a complex network of intrinsic and extrinsic signals. Dysregulation of hematopoiesis, including somatic heterozygous mutations, cytogenetic aberrations, or epigenetic aberrations, are found in hematological malignancies. Advances in the technical field have lead to identification of many genetic and epigenetic alterations in myeloid malignancies. However, their exact role in disease pathogenesis and prognosis remains unclear. The main purpose of this thesis was to explore the role of epigenetic alterations in the myeloid malignancies systemic mastocytosis (SM), the myelodysplastic syndromes (MDS), and acute myeloid leukemia (AML). In study I, we investigated the overall effect on the epigenome caused by Azacitidine in primary MDS bone marrow CD34+ cells. We observed an increase in genes important for the immune system, ERVs, however with no clear correlation with the changes in the epigenome. In study II, four different HDACi were found to dose dependently kill KIT D816V mutated mast cells. Primary patient mast cells were selectively targeted compared to healthy mast cells, and the more aggressive disease, the more sensitive to HDACi mediated killing. In study III, we examined the epigenetic effects of Selenium compounds in AML cell line K562 as well as primary patient AML cells, and found that MSA treatment affected the adhesion capacity of AML cells, which may implicate MSA as a complement to chemotherapy to better target leukemic cells in the bone marrow niche. In study IV, we further investigated the mechanism of action of the findings in study II, delineating the effects of HDACi treatment on mast cell epigenome and transcriptome. We demonstrate a direct effect of HDACi on KIT as well as KIT downstream signaling in D816V KIT mutated cells. In conclusion, this thesis provides insight of the mechanism of action of epigenetically active drugs used in the clinic today, findings that may have direct consequences for improved treatment strategies in myeloid malignancies.
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| 2. |
- Khalkar, Prajakta, et al.
(författare)
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Selenite and methylseleninic acid epigenetically affects distinct gene sets in myeloid leukemia : A genome wide epigenetic analysis
- 2018
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Ingår i: Free Radical Biology & Medicine. - : Elsevier BV. - 0891-5849 .- 1873-4596. ; 117, s. 247-257
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Tidskriftsartikel (refereegranskat)abstract
- Selenium compounds have emerged as promising chemotherapeutic agents with proposed epigenetic effects, however the mechanisms and downstream effects are yet to be studied. Here we assessed the effects of the inorganic selenium compound selenite and the organic form methylseleninic acid (MSA) in a leukemic cell line K562, on active (histone H3 lysine 9 acetylation, H3K9ac and histone H3 lysine 4 tri-methylation, H3K4me3) and repressive (histone H3 lysine 9 tri-methylation, H3K9me3) histone marks by Chromatin immunoprecipitation followed by DNA sequencing (ChIP-Seq). Both selenite and MSA had major effects on histone marks but the effects of MSA were more pronounced. Gene ontology analysis revealed that selenite affected genes involved in response to oxygen and hypoxia, whereas MSA affected distinct gene sets associated with cell adhesion and glucocorticoid receptors, also apparent by global gene expression analysis using RNA sequencing. The correlation to adhesion was functionally confirmed by a significantly weakened ability of MSA treated cells to attach to fibronectin and linked to decreased expression of integrin beta 1. A striking loss of cellular adhesion was also confirmed in primary patient AML cells. Recent strategies to enhance the cytotoxicity of chemotherapeutic drugs by disrupting the interaction between leukemic and stromal cells in the bone marrow are of increasing interest; and organic selenium compounds like MSA might be promising candidates. In conclusion, these results provide new insight on the mechanism of action of selenium compounds, and will be of value for the understanding, usage, and development of new selenium compounds as anticancer agents.
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| 3. |
- Lyberg, Katarina, et al.
(författare)
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Histone deacetylase inhibitor SAHA mediates mast cell death and epigenetic silencing of constitutively active D816V KIT in systemic mastocytosis.
- 2017
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Ingår i: Oncotarget. - : Impact Journals, LLC. - 1949-2553. ; 8:6, s. 9647-9659
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Tidskriftsartikel (refereegranskat)abstract
- Systemic mastocytosis (SM) is a clonal bone marrow disorder, where therapeutical options are limited. Over 90% of the patients carry the D816V point mutation in the KIT receptor that renders this receptor constitutively active. We assessed the sensitivity of primary mast cells (MC) and mast cell lines HMC1.2 (D816V mutated), ROSA (KIT WT) and ROSA (KIT D816V) cells to histone deacetylase inhibitor (HDACi) treatment. We found that of four HDACi, suberoyl anilide hydroxamic acid (SAHA) was the most effective in killing mutated MC. SAHA downregulated KIT, followed by major MC apoptosis. Primary SM patient MC cultured ex vivo were even more sensitive to SAHA than HMC1.2 cells, whereas primary MC from healthy subjects were less affected. There was a correlation between cell death and SM disease severity, where cell death was more pronounced in the case of aggressive SM, with almost 100% cell death among MC from the mast cell leukemia patient. Additionally, ROSA (KIT D816V) was more affected by HDACi than ROSA (KIT WT) cells. Using ChIP qPCR, we found that the level of active chromatin mark H3K18ac/H3 decreased significantly in the KIT region. This epigenetic silencing was seen only in the KIT region and not in control genes upstream and downstream of KIT, indicating that the downregulation of KIT is exerted by specific epigenetic silencing. In conclusion, KIT D816V mutation sensitized MC to HDACi mediated killing, and SAHA may be of value as specific treatment for SM, although the specific mechanism of action requires further investigation.
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