Knockdown of MicroRNA-10a in Acute Myeloid Leukaemia Cells Bearing the Nucleophosmin1 Mutation Causes Cell Death and Reduced Clonogenicity

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1367-1367
Author(s):  
Adam J Bryant ◽  
Catalina A Palma ◽  
Mark Lutherborrow ◽  
Vivek Jayaswal ◽  
Yee Hwa Yang ◽  
...  
Keyword(s):  
Cell Death ◽  
Acute Myeloid Leukaemia ◽  
Myeloid Leukaemia ◽  
Cell Line ◽  
Caspase 3 ◽  
Luciferase Reporter ◽  
Unknown Etiology ◽  
Wild Type ◽  
Over Expression ◽  
Acute Myeloid

Abstract Abstract 1367 Acute Myeloid Leukaemia (AML) with a mutation in the Nucleophosmin1 gene (NPM1c+) accounts for one of the largest subtypes of AML, with an unknown etiology. MicroRNA dysregulation has now been implicated in the oncogenesis of many cancers including AML. We sought to investigate the role of microRNAs in the initiation and development of AML with the NPM1c+ mutation. MicroRNA profiling of bone marrow samples from 28 AML patients and confirmation by qRT-PCR demonstrated a unique microRNA signature in AML-NPM1c+ samples dominated by miR-10a over-expression of 19.6-fold compared to Nucleophosmin1 wild type (NPM1) samples. Functional assessments were performed in the human OCI-AML3 cell line, which is the only cell line to harbour NPM1c+. miR-10a repression was induced by transfection with miRCURY LNA microRNA knockdown probes (Exiqon). Cell growth (MTS) assay demonstrated a significant decrease of 19% in miR-10a knockdown cells compared to the Scrambled control. AnnexinV and Caspase 3 assays assessed the effect of miR-10a knockdown on apoptosis. miR-10a knockdown increased the proportion of AnnexinV positive events when compared to control treated cells by 34.9% and 39.3% at 24 and 48 hours respectively, but had no effect on Caspase 3 expression. Proliferation (BrdU uptake) assays did not show a change, however, clonogenic assays demonstrated a 26.1% decrease in colony number in miR-10a knockdown cells compared to the control. Potential mechanisms were elucidated by determining miR-10a mRNA targets in silico and confirmed by luciferase reporter assays. These included ARNT, GTFH1, ID4, KLF4, MAPRE1, NR4A3, RB1CC1 and TFAP2C. In this study, we have demonstrated that miR-10a was highly differentially expressed between AML-NPM1c+ cells compared to leukaemic cells bearing wild type NPM1. Knockdown of miR-10a in OCI-AML3 cells resulted in increased cell death as detected by AnnexinV binding (but not Caspase 3, indicating an effect independent of the classical apoptotic pathways) and reduced clonogenic capacity. These effects are thought to occur through miR-10a mediated modulation of ARNT, GTFH1, ID4, KLF4, MAPRE1, NR4A3, RB1CC1 and TFAP2C, all of which are associated with neoplastic transformation. Taken together, our results suggest that aberrant miR-10a over-expression in AML-NPM1c+ patients promotes cell survival. Disclosures: No relevant conflicts of interest to declare.

MicroRNA Expression in Acute Myeloid Leukaemia and Their Effects on the Differentiation of Acute Myeloid Leukaemia Cells

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2430-2430
Author(s):  
Catalina A Palma ◽  
Elise Tonna ◽  
Adam J Bryant ◽  
Vivek Jayaswal ◽  
David Agapiou ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Acute Myeloid Leukaemia ◽  
Myeloid Leukaemia ◽  
Normal Karyotype ◽  
Microrna Expression ◽  
Luciferase Reporter ◽  
Maturation Arrest ◽  
Over Expression ◽  
Qrt Pcr ◽  
Acute Myeloid

Abstract Abstract 2430 Acute myeloid leukaemia (AML) is typified by an aberrant halt in maturation of myeloid progenitor cells, leading to uncontrolled proliferation of immature blasts. In the majority of cases of AML with normal karyotype, the underlying cause of the maturation arrest remains unclear. MicroRNAs, small inhibitory RNAs, are known to be dysregulated in cancers and have been postulated to play a causative role in leukaemogenesis. We aimed to investigate the contribution of aberrant microRNA expression to the inhibition of maturation in AML cells. MicroRNA expression profiling was performed on the bone marrow of 28 AML patients with normal karyotype and 8 normal controls. Differential expression was confirmed by qRT-PCR. We found that the expression of a panel of 12 microRNAs was able to accurately separate AML-M1 and AML-M5 subtypes. The AML-M1 subtype represents a more immature cell population when compared to the monoblast morphology observed in AML-M5. Four candidate microRNAs, miR-181a, -146a, -130a and -135b were selected for further investigation based in their putative targeting of key monocytic transcription factors as determined by in silico modelling followed by luciferase assays. In vitro monocyte and macrophage differentiation of HL60 and NB4 cell lines with 1,25-dihydroxyvitamin D3 and/or phorbol-12-myristate-13-acetate treatment resulted in a significant decrease in all four candidate microRNAs (measured by qRT-PCR), supporting the hypothesis that candidate microRNA over-expression in AML-M1 may contribute to its maturation arrest. Over-expression of the candidate microRNAs by transfection with Pre-miR microRNA precursor molecules (Ambion) into the HL60 and NB4 monocyte differentiation model, resulted in the significant suppression of CD14 (Figure, *p <0.05 compared to Scrambled control) and CD15 expression, markers of monocytes and granulocytes respectively. Conversely, knockdown of miR-181a, -146a, -130a and -135b with miRCURY LNA microRNA knockdown probes (Exiqon) induced an increase in CD14 expression in HL60 cells compared to non-targeting Scrambled control. An important regulatory role of these microRNAs in myeloid/monocytic differentiation is strongly suggested by their targeted suppression of the key transcription factors KLF4, MAFB, IRF8, HOXA10, MCL1 and PU.1 which was confirmed by luciferase reporter assay. This study provides evidence that the over-expressed microRNAs discovered in our profiling work between AML-M1 and AML-M5 are biologically relevant microRNAs, which have the potential to affect the maturation potential of AML cells. Disclosures: No relevant conflicts of interest to declare.

scholarly journals miR-10a is aberrantly overexpressed in Nucleophosmin1 mutated acute myeloid leukaemia and its suppression induces cell death

2012 ◽  
Vol 11 (1) ◽  
pp. 8 ◽  
Author(s):  
Adam Bryant ◽  
Catalina A Palma ◽  
Vivek Jayaswal ◽  
Yee Yang ◽  
Mark Lutherborrow ◽  
...  
Keyword(s):  
Cell Death ◽  
Acute Myeloid Leukaemia ◽  
Myeloid Leukaemia ◽  
Acute Myeloid

scholarly journals Preferential transcription of the mutated allele in NPM1 mutated acute myeloid leukaemia

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
G. D. Bailey ◽  
L. Doolan ◽  
A. Baskar ◽  
L. C. Smith ◽  
C. H. Seedhouse
Keyword(s):  
Acute Myeloid Leukemia ◽  
Acute Myeloid Leukaemia ◽  
Myeloid Leukaemia ◽  
Myeloid Leukemia ◽  
Splice Variants ◽  
Wild Type ◽  
Significant Bias ◽  
Acute Myeloid

Abstract Nucleophosmin is commonly both over-expressed and mutated in acute myeloid leukemia (AML). NPM1 mutations are always heterozygous. In addition, NPM1 has a number of different splice variants with the major variant encoded by exons 1–9 and 11–12 (NPM1.1). Further variants include NPM1.2 which lacks exons 8 and 10 and NPM1.3 which comprises exons 1–10 (and so lacks the region of sequence mutated in AML). In this study we quantified the expression of these three variants in 108 AML patient samples with and without NPM1 mutations and also assessed the level of expression from the wild-type and mutant alleles in variants NPM1.1 and NPM1.2. The results show that NPM1.1 is the most commonly expressed variant, however transcripts from wild-type and mutated alleles do not occur at equal levels, with a significant bias toward the mutated allele. Considering the involvement of mutant nucleophosmin in the progression and maintenance of AML, a bias towards mutated transcripts could have a significant impact on disease maintenance.

Characteristics of a Cell Line Established from a Child with Familial Acute Myeloid Leukaemia

2008 ◽  
Vol 46 (1) ◽  
pp. 23-31 ◽  
Author(s):  
Patricia Fischer ◽  
A. Karpas ◽  
Elisabeth Nacheva ◽  
O. Haas ◽  
Heide Winterixitner ◽  
...  
Keyword(s):  
Acute Myeloid Leukaemia ◽  
Myeloid Leukaemia ◽  
Cell Line ◽  
A Cell ◽  
Acute Myeloid

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.

scholarly journals Hydroxyurea synergizes with valproic acid in wild-type p53 acute myeloid leukaemia

Oncotarget ◽  
2016 ◽  
Vol 7 (7) ◽  
pp. 8105-8118 ◽  
Author(s):  
Calum Leitch ◽  
Tereza Osdal ◽  
Vibeke Andresen ◽  
Maren Molland ◽  
Silje Kristiansen ◽  
...  
Keyword(s):  
Valproic Acid ◽  
Acute Myeloid Leukaemia ◽  
Myeloid Leukaemia ◽  
Wild Type ◽  
Wild Type P53 ◽  
Acute Myeloid
Sign in / Sign up

Export Citation Format

Share Document