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Project description:Myelodysplastic syndrome (MDS), a largely incurable hematological malignancy, is derived from aberrant clonal hematopoietic stem/progenitor cells (HSPCs) that persist after conventional therapies. Defining the mechanisms underlying MDS HSPC maintenance is critical for developing MDS therapy. The deacetylase SIRT1 regulates stem cell proliferation, survival, and self-renewal by deacetylating downstream proteins. Here we show that SIRT1 protein levels were downregulated in MDS HSPCs. Genetic or pharmacological activation of SIRT1 inhibited MDS HSPC functions, whereas SIRT1 deficiency enhanced MDS HSPC self-renewal. Mechanistically, the inhibitory effects of SIRT1 were dependent on TET2, a safeguard against HSPC transformation. SIRT1 deacetylated TET2 at conserved lysine residues in its catalytic domain, enhancing TET2 activity. Our genome-wide analysis identified cancer-related genes regulated by the SIRT1/TET2 axis. SIRT1 activation also inhibited functions of MDS HSPCs from patients with TET2 heterozygous mutations. Altogether, our results indicate that restoring TET2 function through SIRT1 activation represents a promising means to target MDS HSPCs.
| S-EPMC6143172 | biostudies-literature
Project description:Improved understanding of mechanisms regulating myelodysplastic syndrome (MDS) hematopoietic stem/progenitor cell (HSPC) growth and self-renewal is critical for developing MDS therapy. We revealed a novel regulatory axis that SIRT1-deficiency induced TET2 hyperacetylation promotes MDS HSPC functions, and provide an approach to target MDS HSPCs by activating SIRT1 deacetylase.
2018-08-13 | GSE117363 | GEO
Project description:Improved understanding of mechanisms regulating myelodysplastic syndrome (MDS) hematopoietic stem/progenitor cell (HSPC) growth and self-renewal is critical for developing MDS therapy. We revealed a novel regulatory axis that SIRT1-deficiency induced TET2 hyperacetylation promotes MDS HSPC functions, and provide an approach to target MDS HSPCs by activating SIRT1 deacetylase. Four Groups: Group1: MDS-L cells transduced with lentiviral vector targeting non-silence squence (control shRNA for SIRT1); Group2: MDS-L cells transduced with lentiviral vector containing interference squence targeting SIRT1 (SIRT shRNA); Group 3: MDS-L cells transduced with lentiviral vector targeting non-silence squence (control shRNA for TET2); Group 4: MDS-L cells transduced with lentiviral vector containing interference squence targeting TET2 (TET2 shRNA).
2018-08-13 | GSE117272 | GEO
Project description:SIRT1 Activation Disrupts Maintenance of Myelodysplastic Syndrome Stem and Progenitor Cells by Restoring TET2 Function
| PRJNA481954 | ENA
Project description:SIRT1 Activation Disrupts Maintenance of Myelodysplastic Syndrome Stem and Progenitor Cells by Restoring TET2 Function [hMeDIP-Seq]
| PRJNA481884 | ENA
Project description:SIRT1 Activation Disrupts Maintenance of Myelodysplastic Syndrome Stem and Progenitor Cells by Restoring TET2 Function [microarray expression profiling]
| PRJNA481584 | ENA
Project description:BackgroundMyelodysplastic syndrome (MDS) arises from a rare population of aberrant hematopoietic stem and progenitor cells (HSPCs). These cells are relatively quiescent and therefore treatment resistant. Understanding mechanisms underlying their maintenance is critical for effective MDS treatment.MethodsWe evaluated microRNA-126 (miR-126) levels in MDS patients' sample and in a NUP98-HOXD13 (NHD13) murine MDS model along with their normal controls and defined its role in MDS HSPCs' maintenance by inhibiting miR-126 expression in vitro and in vivo. Identification of miR-126 effectors was conducted using biotinylated miR-126 pulldown coupled with transcriptome analysis. We also tested the therapeutic activity of our anti-miR-126 oligodeoxynucleotide (miRisten) in human MDS xenografts and murine MDS models.ResultsmiR-126 levels were higher in bone marrow mononuclear cells from MDS patients and NHD13 mice relative to their respective normal controls (P < 0.001). Genetic deletion of miR-126 in NHD13 mice decreased quiescence and self-renewal capacity of MDS HSPCs, and alleviated MDS symptoms of NHD13 mice. Ex vivo exposure to miRisten increased cell cycling, reduced colony-forming capacity, and enhanced apoptosis in human MDS HSPCs, but spared normal human HSPCs. In vivo miRisten administration partially reversed pancytopenia in NHD13 mice and blocked the leukemic transformation (combination group vs DAC group, P < 0.0001). Mechanistically, we identified the non-coding RNA PTTG3P as a novel miR-126 target. Lower PTTG3P levels were associated with a shorter overall survival in MDS patients.ConclusionsMiR-126 plays crucial roles in MDS HSPC maintenance. Therapeutic targeting of miR-126 is a potentially novel approach in MDS.
| S-EPMC8516361 | biostudies-literature
Project description:The ten-eleven translocation 2 gene (TET2) encodes a member of the TET family of DNA methylcytosine oxidases that converts 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) to initiate the demethylation of DNA within genomic CpG islands. Somatic loss-of-function mutations of TET2 are frequently observed in human myelodysplastic syndrome (MDS), which is a clonal malignancy characterized by dysplastic changes of developing blood cell progenitors, leading to ineffective hematopoiesis. We used genome-editing technology to disrupt the zebrafish Tet2 catalytic domain. tet2(m/m) (homozygous for the mutation) zebrafish exhibited normal embryonic and larval hematopoiesis but developed progressive clonal myelodysplasia as they aged, culminating in myelodysplastic syndromes (MDS) at 24 months of age, with dysplasia of myeloid progenitor cells and anemia with abnormal circulating erythrocytes. The resultant tet2(m/m) mutant zebrafish lines show decreased levels of 5hmC in hematopoietic cells of the kidney marrow but not in other cell types, most likely reflecting the ability of other Tet family members to provide this enzymatic activity in nonhematopoietic tissues but not in hematopoietic cells. tet2(m/m) zebrafish are viable and fertile, providing an ideal model to dissect altered pathways in hematopoietic cells and, for small-molecule screens in embryos, to identify compounds with specific activity against tet2 mutant cells.
| S-EPMC4323485 | biostudies-literature
Project description:Aberrant DNA methylation often silences transcription of tumor-suppressor genes and is considered a hallmark of myeloid neoplasms. Similarly, histone deacetylation represses transcription of genes responsible for cell differentiation/death. A previous clinical study suggested potential pharmacodynamic antagonism between histone deacetylase inhibitors (HDACi) and DNA hypomethylating agents (HMA). Herein, to determine such antagonism, we used MDS/AML lines and NHD13 transgenic mice, and demonstrated that treatment with the pan-HDACi suberoylanilide hydroxamic acid (SAHA) significantly decreased TET2 expression and global 5-hydroxymethylcytosine (5hmC) levels. Mechanistically, our RNAi screen revealed that HDAC4 was responsible for maintaining TET2 levels. Accordingly, HDAC4 knockout reduced expression levels of MTSS1, a known TET2 target, an event associated with decreased 5hmC enrichment on the MTSS1 enhancer. Retrospective analysis of GEO datasets demonstrated that lower HDAC4 levels predict worse prognosis for AML patients. In an MDS-L xenografted immunodeficient mouse model, vitamin C co-treatment prevented TET2 loss of activity seen following SAHA treatment. Accordingly, vitamin C co-treatment further reduced MDS-L cell engraftment relative to SAHA alone. In summary, our findings suggest that co-administration of a TET2 agonist with pan-HDACi treatment could effectively counter potential diminution in TET2 activity resulting from pan-HDACi treatment alone, providing a rationale for evaluating such combinations against high-risk MDS/AML.
| S-EPMC7521497 | biostudies-literature
Project description:Myelodysplastic syndromes (MDS) with ring sideroblasts are hematopoietic stem cell disorders with erythroid dysplasia and mutations in the SF3B1 splicing factor gene. Patients with MDS with SF3B1 mutations often accumulate excessive tissue iron, even in the absence of transfusions, but the mechanisms that are responsible for their parenchymal iron overload are unknown. Body iron content, tissue distribution, and the supply of iron for erythropoiesis are controlled by the hormone hepcidin, which is regulated by erythroblasts through secretion of the erythroid hormone erythroferrone (ERFE). Here, we identified an alternative ERFE transcript in patients with MDS with the SF3B1 mutation. Induction of this ERFE transcript in primary SF3B1-mutated bone marrow erythroblasts generated a variant protein that maintained the capacity to suppress hepcidin transcription. Plasma concentrations of ERFE were higher in patients with MDS with an SF3B1 gene mutation than in patients with SF3B1 wild-type MDS. Thus, hepcidin suppression by a variant ERFE is likely responsible for the increased iron loading in patients with SF3B1-mutated MDS, suggesting that ERFE could be targeted to prevent iron-mediated toxicity. The expression of the variant ERFE transcript that was restricted to SF3B1-mutated erythroblasts decreased in lenalidomide-responsive anemic patients, identifying variant ERFE as a specific biomarker of clonal erythropoiesis.
| S-EPMC8005358 | biostudies-literature