scholarly journals Ablation of MYB-dependent leukaemia phenotype in MLL-driven AML correlates with increased expression of MAFB

2020 ◽  
Author(s):  
C Ward ◽  
P Cauchy ◽  
DS Walton ◽  
ML Clarke ◽  
D Blakemore ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Acute Myeloid Leukaemia ◽  
General Trend ◽  
Reciprocal Relationship ◽  
Myeloid Differentiation ◽  
Complex Karyotype ◽  
Aberrant Expression ◽  
Two Factors ◽  
Human Leukaemia ◽  
Acute Myeloid

ABSTRACTThe transcription factor MYB plays a pivotal role in haematopoietic homeostasis and its aberrant expression is involved in the genesis and maintenance of acute myeloid leukaemia (AML). Our previous work has demonstrated that not all AML types display the same dependency on MYB expression and that MYB dependence is dictated by the nature of the driver mutation. However, whether this difference in MYB dependency is a general trend in AML still remains to be further elucidated. In this study, we investigate the importance of MYB in human leukaemia by performing siRNA-mediated knock-down in cell line models of AML with different driver lesions. We show that the characteristic reduction in proliferation and the concomitant induction of myeloid differentiation that is observed in MLL-fusion-driven leukaemia upon MYB suppression is not seen in AML cells with a complex karyotype. By performing transcriptome analysis, we demonstrate that a strong activation of MAFB expression driven by MYB ablation is restricted to MYB-dependent cells. In line with these observations, stratification of publicly available patient data reveals a reciprocal relationship between the expression of MYB and MAFB, highlighting a novel connection between those two factors in AML.

Immunophenotypic dysplasia and aberrant T-cell antigen expression in acute myeloid leukaemia with complex karyotype and TP53 mutations

2018 ◽  
Vol 71 (12) ◽  
pp. 1051-1059
Author(s):  
Katelyn C Dannheim ◽  
Olga Pozdnyakova ◽  
Paola Dal Cin ◽  
Olga K Weinberg
Keyword(s):  
T Cell ◽  
Acute Myeloid Leukaemia ◽  
Myeloid Leukaemia ◽  
Normal Karyotype ◽  
Antigen Expression ◽  
Complex Karyotype ◽  
Aberrant Expression ◽  
T Cell Antigens ◽  
Molecular Aberrations ◽  
Acute Myeloid

AimsCytogenetic and molecular aberrations are the strongest factors in determining outcome in acute myeloid leukaemia (AML). AML with complex karyotype confers a particularly poor prognosis and is associated with morphologic dysplasia. Flow cytometric immunophenotyping (FCI) has been investigated in defining dysplasia within myelodysplastic syndromes, but little is known about immunophenotypic dysplasia in AML and correlation with genetic abnormalities. This study aimed to explore differences in antigen expression by FCI in AML with complex karyotype (AML-CK) and AML with complex karyotype and TP53 mutations (AML-TP53) compared with AML with normal karyotype (AML-NK).MethodsTwenty-five cases of AML-CK, 13 of which had abnormalities of TP53, were compared with 83 cases of AML-NK using FCI.ResultsOur findings demonstrated brighter expression of CD34 with decreased CD33 and aberrant expression of CD5 in blasts of AML-CK, while AML-TP53 blasts exhibited brighter expression of CD13. Granulocytes in AML-CK exhibited brighter expression of CD5, CD7, CD10 and CD14, with brighter CD3 also seen in AML-TP53.ConclusionsOur results suggest that immunophenotypic dysplasia correlates with complex karyotype and TP53 mutation, including increased expression of T-cell antigens.

Aberrant Expression of CD Markers in Acute Myeloid Leukaemia

2018 ◽  
Vol 2 (01) ◽  
pp. 14-16
Author(s):  
Abul Kalam Azad ◽  
Md. Rafiquzzaman Khan ◽  
ABM Hasan Habib ◽  
Md. Abdul Wadud Miah ◽  
Masuda Begum
Keyword(s):  
Flow Cytometry ◽  
Acute Myeloid Leukaemia ◽  
Myeloid Leukaemia ◽  
Acute Leukaemia ◽  
Antigen Expression ◽  
Aberrant Expression ◽  
Female Ratio ◽  
Cd Antigen ◽  
Cd Markers ◽  
Acute Myeloid

Background: Aberrant expression of cluster differentiation (CD) antigen marker is associated with poor outcome of acute leukaemia. Objective: Aim of this study is to determine the frequency and pattern of aberrant expression of CD markers in acute myeloid leukaemia patients in Bangladesh. Methods: This retrospective data analysis was conducted in the Department of Haematology, Bangabandhu Sheikh Mujib Medical University (BSMMU) to assess the frequency of aberrant CD antigen expression in acute myeloid leukaemia from October 2016 to September 2017. During this period, we did one hundred flow cytometry of acute leukaemia patients and among them we found 48 acute myeloid Leukaemia (AML) who were included in this study. Result: Mean age of patients was 35 years (SD­ +14 years; Rang 3 to 50 years) with male: female ratio of 0.92. Four colour flow cytometry was done on fresh bone marrow aspirates and peripheral blood. Among 48 AML patients, aberrant CD expression was observed in 58% cases.  CD5 and cCD79a lymphoid markers were seen to be expressed in 32% cases of AML. Aberrant cCD3 and CD7 were expressed in 29% and 25% cases respectively and aberrant CD10, CD19, cCD22 were expressed in 11%, 3%, 3% cases acute myeloid leukaemia patients respectively. Conclusion: Aberrant CD antigen expression is not uncommon in AML patients of Bangladeshi population that may adversely affect the treatment outcome of the disease.

Aberrant Expression of Hepatocyte Growth Factor Induces Autocrine MET Activation Providing a Novel Therapeutic Target In Acute Myeloid Leukemia.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1042-1042
Author(s):  
Alex Kentsis ◽  
Takaomi Sanda ◽  
Vu Ngo ◽  
Scott J. Rodig ◽  
Jeffery Kutok ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Growth Factor ◽  
Hepatocyte Growth Factor ◽  
Therapeutic Target ◽  
Myeloid Leukemia ◽  
Complex Karyotype ◽  
Aberrant Expression ◽  
Hepatocyte Growth ◽  
Acute Myeloid ◽  
Novel Therapeutic

Abstract Abstract 1042 Despite improvements in the treatment of acute myeloid leukemia (AML), high risk disease such as complex aberrant karyotype AML remains largely refractory to current therapy, and is mostly fatal. Identification of effective therapeutic targets by using candidate gene approaches has been limited by the number and variety of genetic defects associated with AML. Thus, we carried out a genome-wide functional screen in complex karyotype AML using a retroviral library of short hairpin RNAs (shRNAs), and discovered that shRNA-mediated depletion of hepatocyte growth factor (HGF) specifically inhibits growth of AML cells but not a panel of lymphoid cancer cells. HGF was to found to be aberrantly expressed in about 15% of patients with AML, including most patients with complex karyotype disease. In contrast to normal CD34+ cells that express MET (but not HGF), 5 of 7 cell lines derived from patients with complex karyotype AML exhibited aberrant expression of HGF that was associated with autocrine activation of its receptor MET. Depletion of HGF or MET using multiple independent shRNAs profoundly reduced proliferation and induced cell death in AML cells lines that express HGF but not those that lack HGF expression. Inhibition of MET using the tyrosine kinase inhibitor (SU11274) or HGF using neutralizing anti-HGF antibody (R&D Systems) also inhibited growth and induced apoptosis in AML cell lines dependent on HGF/MET activation but not those that lack HGF expression. Thus, aberrant HGF expression causes autocrine MET activation and oncogene dependence in a subset of patients with AML, confers sensitivity to HGF/MET inhibition, and provides a novel therapeutic target for this otherwise lethal disease. Disclosures: No relevant conflicts of interest to declare.

Elucidation and Therapeutic Targeting Of The Molecular Mechanism Of TRIB2-Mediated Acute Myeloid Leukaemia

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3792-3792
Author(s):  
Fiona Lohan ◽  
Ciaran Forde ◽  
Mara Salome ◽  
Caitriona O'Connor ◽  
Fiona Bailey ◽  
...  
Keyword(s):  
Amino Acids ◽  
Cell Death ◽  
Acute Myeloid Leukaemia ◽  
Myeloid Leukaemia ◽  
Kinase Activity ◽  
Proteasomal Degradation ◽  
Myeloid Differentiation ◽  
Direct Binding ◽  
Targeted Inhibition ◽  
Acute Myeloid

Abstract The pseudokinase TRIB2 is a potent acute myeloid leukaemia (AML) oncogene, capable of inducing transplantable AML with a relatively short latency in murine models. Functionally, the oncogencity of TRIB2 has been linked to its degradation of CCAAT/enhancer binding-protein-alpha (C/EBPα), a transcription factor necessary for regulation of haematopoietic stem cells (HSC) and myeloid differentiation and is mutated in ∼10-15% of cytogenetically normal AMLs. Previously, we have demonstrated that elevated TRIB2 mRNA expression is associated with a small subset of C/EBPα dysregulated AML patients. However in our analysis of primary AML patient samples we reveal detectably high TRIB2 protein expression in a greater number of samples than predicted from mRNA studies compared to normal peripheral blood mononuclear cells. Here, using in vivo ubiquitination assays we determined that TRIB2 exerts its effect through K48 specific ubiquitin-dependent proteasomal degradation of C/EBPα. Peptide array analysis identified the specific amino acids involved in the direct binding of these two proteins. Site-directed mutagenesis of these amino acids demonstrated that the direct binding of TRIB2 and C/EBPα was required for TRIB2-mediated C/EBPα degradation. In order to determine if posttranslational modification of C/EBPα was a trigger for TRIB2-mediated binding and degradation, we assessed the phosphorylation of C/EBPα, often a modification involved in target substrate ubiquitination. We found that TRIB2 decreased the levels of phosphorylated Serine 21 (S21) C/EBPα through preferential binding to the phosphorylated form of S21 C/EBPα and mediating its K48 specific ubiquitin-dependent proteasomal degradation. While TRIB2 retains the canonical amino acid motifs of a kinase and the ability to bind ATP, indicative of kinase activity, the absence of phosphorylated S21 C/EBPα in the presence of TRIB2 suggests that it does not have sufficient kinase activity to enable efficient phosphotransfer. The presence of TRIB2 further blocked the ability of mitogenic stimuli to phosphorylate S21 of C/EBPα. TRIB2 thus acts to perturb the regulation and function of C/EBPα phosphorylation ultimately leading to its degradation. We propose this contributes to the leukaemic phenotype of AML cells which include increased self-renewal and proliferation. Using clinically available inhibitors of the proteasomal degradation pathway we have investigated the targeted inhibition of the TRIB2 degradation function to induce cell death in AML cells. In TRIB2 overexpressing AML cell lines, and in AML patient samples identified to have elevated levels of TRIB2, we have demonstrated that elevated TRIB2 expressing samples are more sensitive than low TRIB2 expressing samples to cell death induced by proteasomal inhibition. Our data shows that in the presence of TRIB2 phosphorylated S21 C/EBPα is a trigger for its ubiquitin dependent degradation. We propose TRIB2 mediates is leukaemogenic effects in AML through direct protein-protein interaction, perturbation of phosphorylation signalling, resulting ultimately in proteasomal mediated degradation of its target C/EBPα. As C/EBPα plays a key role in both stem cell function and myeloid differentiation in AML, the targeted inhibition of TRIB2-mediated C/EBPα degradation may provide therapeutic avenues in AML. Disclosures: No relevant conflicts of interest to declare.

Gene Expression Analysis of Bexarotene Differentiated Acute Myeloid Leukemias Identifies Known and Novel Gene Targets.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1199-1199
Author(s):  
Patricia Vanessa Sanchez ◽  
Reid P Bissonnette ◽  
Donald E Tsai ◽  
Martin Carroll
Keyword(s):  
Transcription Factor ◽  
Retinoic Acid ◽  
Cell Differentiation ◽  
Cell Lines ◽  
Leukemic Cell ◽  
Myeloid Differentiation ◽  
Induced Differentiation ◽  
Pparγ Agonist ◽  
Acute Myeloid

Abstract Despite advances in understanding the molecular pathogenesis of acute myeloid leukemia (AML), therapy for relapsed disease remains inadequate with high mortalities. Clinicians at the University of Pennsylvania have demonstrated that the FDA approved retinoid X receptor (RXR) agonist bexarotene (Targretin™) stimulates leukemic cell differentiation in a subset patents with relapsed AML leading to clinical responses. This underscores the importance of identifying the mechanism by which bexarotene induces differentiation in AML in order to enhance the efficacy of this therapeutic approach. To understand the role of bexarotene and RXR receptors in leukemic cell differentiation, we initially utilized a pharmacogenetic approach to study the effects of bexarotene on AML cell lines using combinations of bexarotene with other differentiation induction agents. These studies demonstrate that bexarotene induces myeloid differentiation in MOLM14, HL60, THP-1, and NB4 cell lines but not in the myeloblastic cell line KG1a. Combination treatment of AML cell lines with bexarotene in combination with all trans retinoic acid (ATRA) enhanced differentiation suggesting that the mechanism of action for bexarotene is through RARα (retinoic acid receptor)/RXRα heterodimer stimulation. Consistent with this, differentiation induced by the drug combination was effectively blocked by the RAR antagonist, LG100815 and partially blocked by the RXR antagonist, LG101208. In contrast, bexarotene does not cooperate with valproic acid, theophylline, the PPARγ agonist rosiglitazone, or the LXR agonist T0901317. Preliminary data from quantitative RT-PCR and Affymetrix microarray analysis of bexarotene responsive AML cell lines at 3, 6, 12, and 96 hours post treatment has identified a subset of genes potentially regulated by bexarotene. CEBPε, a transcription factor known to play a critical role in granulopoiesis and PIM-1, a known oncogenic transcription factor, were among the genes that were significantly upregulated after bexarotene treatment of AML cells. Analysis of the functional role of C/EBPε in retinoid induced differentiation will be presented. Overall, this data supports the hypothesis that bexarotene, like ATRA, induces myeloid differentiation through activation of a RAR/RXR heterodimeric partner. However, other data suggests the presence of RAR independent pathways of signaling. LG100268, a pure RXR agonist induced myeloid differentiaton although not as robustly as bexarotene. Analysis of RAR and RXR mRNA expression in AML cell lines demonstrates that bexarotene does not induce expression of RARβ or p21, known targets induced by ATRA during myeloid differentiation. Chromatin immunoprecipitation assays demonstrate RXRα occupancy at RARβ and p21 promoter regions containing retinoid response elements (RARE). However, expression of these genes does not correlate with bexarotene-induced differentiation. This data suggests that although their expression has been linked to ATRA responsiveness, induction of RARβ and p21 expression is not necessary for retinoid induced myeloid differentiation. In summary, bexarotene induces myeloid differentiation through RAR dependent and independent pathways. Further analysis of the signaling events necessary for induction of myeloid differentiation by bexarotene may allow for improved selection of patients with AML who will respond to bexarotene.

scholarly journals The Transcription Factor PU.1 Controls a Reversible Differentiation Program in Acute Myeloid Leukemia

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3930-3930
Author(s):  
Mark D McKenzie ◽  
Margherita Ghisi ◽  
Luisa Cimmino ◽  
Michael Erlichster ◽  
Ethan P Oxley ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Transcription Factor ◽  
Myeloid Leukemia ◽  
Conflicts Of Interest ◽  
Significant Loss ◽  
Polymorphonuclear Neutrophil ◽  
Myeloid Differentiation ◽  
Myeloid Lineage ◽  
Acute Myeloid

Abstract Background: Acute myeloid leukemia (AML) is an aggressive malignancy characterized by clonal expansion of transformed myeloid precursors that fail to differentiate into mature cells. Since myeloid lineage maturation curbs self-renewal and is considered irreversible, engaging this process in AML is an attractive therapeutic strategy. Results: Normal myeloid differentiation requires the transcription factor PU.1 (SPI1), which is functionally compromised in several AML subtypes and is directly inhibited by the recurrent fusion oncoproteins AML1-ETO and PML-RARA. To examine the importance of PU.1 suppression in AML maintenance in vivo, we have combined RNAi-mediated PU.1 inhibition with p53 deficiency to drive highly aggressive AML in mice. Using these models we find that restoring endogenous PU.1 activity in established AML in vivo is sufficient to trigger robust transcriptional, immunophenotypic, and morphological differentiation of leukemic blasts, yielding polymorphonuclear, neutrophil-like cells. Maturation of AML is associated with significant loss of cell viability and yields sustained disease clearance in vivo. Although PU.1 restoration is potently anti-leukemic, remarkably we find that subsequent suppression of PU.1 in mature neutrophil-like cells reverts them to a transformed state within several days. While mature AML-derived cells are slower to form blast colonies in methylcellulose cultures, their clonogenic frequency is only reduced four-fold relative to AML blasts suggesting highly efficient de-differentiation. Conclusions: These results demonstrate that triggering myeloid differentiation can effectively resolve a p53-deficient model of treatment resistant AML, but also identify a previously unrecognised ability of AML cells to bidirectionally transition between transformed and differentiated states based on the activity of a single transcription factor. Our findings challenge the concept of 'terminal differentiation' in AML and highlight the importance of therapeutically eradicating leukemia cells at all stages of myeloid lineage maturation. Disclosures No relevant conflicts of interest to declare.

Genes Located within the del(9q) Commonly Deleted Region Are Down-Regualted in Acute Myeloid Leukaemia.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2040-2040
Author(s):  
Zheng Zhao ◽  
Sarah Daly ◽  
John Liu Yin ◽  
David Sweetser ◽  
Jacqueline Boultwood ◽  
...  
Keyword(s):  
Acute Myeloid Leukaemia ◽  
Myeloid Leukaemia ◽  
Normal Karyotype ◽  
Complex Karyotype ◽  
Down Regulation ◽  
Expression Levels ◽  
Normal Individuals ◽  
Low Expression ◽  
Acute Myeloid

Abstract Deletions of 9q are recurring cytogenetic abnormalities in acute myeloid leukaemia (AML). In approximately one-third of cases del(9q) occurs in association with t(8;21). We have previously identified a 2.4Mb region located on 9q21.32–21.33 which is deleted in cases of del(9q) AML - the del(9q) commonly deleted region (CDR). This region encodes 11 genes which we have also previously shown not to be mutated in del(9q) AML. In order to further investigate the role of these genes in AML and in particular to elucidate the pathogenesis of del(9q) AML we have examined the expression of these genes in AML. RNA was extracted from the bone marrow or peripheral blood of patients with AML at the time of diagnosis. Patient samples from the following cytogenetic subgroups were included in this study: (1) del(9q) AML (n=8) - this includes 3 patients with associated t(8;21); (2) t(8;21) but no del(9q) (n=15); (3) Normal karyotype (n=6); (4) Complex Karyotype (n=6). Taqman assays were designed for 9 of the 11 genes located within the del(9q) CDR: FRMD3; ENSG00000148057; UBQLN1; GKAP42; Q9UF54; Q8N2B1; Q9H9A7; SLC28A3; NTRK2. For the other 2 genes within the region Taqman assays could not be performed because of uniformly low expression levels (Q8IZ41) and lack of specificity of primer-design (HNRPK). CD34-purified progenitors from normal individuals were used as controls. It was found that 6 of the 9 genes were significantly down-regulated in del(9q) AML (p<0.05): ENSG00000148057; UBQLN1; Q9UF54; Q8N2B1; Q9H9A7; NTRK2. Since del(9q) is commonly associated with t(8;21), cases of t(8;21) in which del(9q) was not present were also analysed for the expression levels of the del(9q) CDR genes. It was found that 5 of the 9 genes were significantly down regulated in t(8;21) AML (ENSG00000148057; Q9UF54; Q8N2B1; Q9H9A7; SLC28A3) (p<0.05). Only two of these genes were found to be down-regulated in AML of normal karyotype (Q9H9A7 and UBQLN1) (p<0.05) and no significant down-regulation was detected in any of these genes in AML of complex karyotype. Our findings indicate that several genes from within the del(9q) AML CDR are down-regulated in del(9q) AML. A similar pattern of down-regulation is found in cases of t(8;21) even in the absence of del(9q) AML. This suggests that down-regulation of one or more of these genes may be important in the pathogenesis of AML. It may therefore be hypothesized that this pattern of gene down-regulation provides a mechanism common to the development of AML with both del(9q) and t(8;21).

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