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1.  Isoform-Specific Potentiation of Stem and Progenitor Cell Engraftment by AML1/RUNX1  
PLoS Medicine  2007;4(5):e172.
AML1/RUNX1 is the most frequently mutated gene in leukaemia and is central to the normal biology of hematopoietic stem and progenitor cells. However, the role of different AML1 isoforms within these primitive compartments is unclear. Here we investigate whether altering relative expression of AML1 isoforms impacts the balance between cell self-renewal and differentiation in vitro and in vivo.
Methods and Findings
The human AML1a isoform encodes a truncated molecule with DNA-binding but no transactivation capacity. We used a retrovirus-based approach to transduce AML1a into primitive haematopoietic cells isolated from the mouse. We observed that enforced AML1a expression increased the competitive engraftment potential of murine long-term reconstituting stem cells with the proportion of AML1a-expressing cells increasing over time in both primary and secondary recipients. Furthermore, AML1a expression dramatically increased primitive and committed progenitor activity in engrafted animals as assessed by long-term culture, cobblestone formation, and colony assays. In contrast, expression of the full-length isoform AML1b abrogated engraftment potential. In vitro, AML1b promoted differentiation while AML1a promoted proliferation of progenitors capable of short-term lymphomyeloid engraftment. Consistent with these findings, the relative abundance of AML1a was highest in the primitive stem/progenitor compartment of human cord blood, and forced expression of AML1a in these cells enhanced maintenance of primitive potential both in vitro and in vivo.
These data demonstrate that the “a” isoform of AML1 has the capacity to potentiate stem and progenitor cell engraftment, both of which are required for successful clinical transplantation. This activity is consistent with its expression pattern in both normal and leukaemic cells. Manipulating the balance of AML1 isoform expression may offer novel therapeutic strategies, exploitable in the contexts of leukaemia and also in cord blood transplantation in adults, in whom stem and progenitor cell numbers are often limiting.
The truncated "a" isoform of AML1 is shown to have the capacity to potentiate stem and progenitor cell engraftment, both of which are required for successful clinical transplantation.
Editors' Summary
Blood contains red blood cells (which carry oxygen round the body), platelets (which help the blood to clot), and white blood cells (which fight off infections). All these cells, which are regularly replaced, are derived from hematopoietic stem cells, blood-forming cells present in the bone marrow. Like all stem cells, hematopoietic stem cells self-renew (reproduce themselves) and produce committed progenitor cells, which develop into mature blood cells in a process called hematopoiesis. Many proteins control hematopoiesis, some of which are called transcription factors; these factors bind to DNA through their DNA-binding domain and then control the expression of genes (that is, how DNA is turned into proteins) through particular parts of the protein (their transcription regulatory domains). An important hematopoietic transcription factor is AML1—a protein first identified because of its involvement in acute myelogenous leukemia (AML, a form of blood cancer). Mutations (changes) in the AML1 gene are now known to be present in other types of leukemia, which are often characterized by overproliferation of immature blood cells.
Why Was This Study Done?
Because of AML1′s crucial role in hematopoiesis, knowing more about which genes it regulates and how its activity is regulated could provide clues to treating leukemia and to improving hematopoietic cell transplantation. Many cancer treatments destroy hematopoietic stem cells, leaving patients vulnerable to infection. Transplants of bone marrow or cord blood (the cord that links mother and baby during pregnancy contains peripheral blood stem cells) can replace the missing cells, but cord blood in particular often contains insufficient stem cells for successful transplantation. It would be useful, therefore, to expand the stem cell content of these tissues before transplantation. In this study, the researchers investigated the effect of AML1 on self-renewal and differentiation of hematopoietic stem and progenitor cells in the laboratory (in vitro) and in animals (in vivo). In particular, they have asked how two isoforms (closely related versions) of AML1 affect the ability of these cells to grow and differentiate (engraft) in mice after transplantation.
What Did the Researchers Do and Find?
The researchers artificially expressed AML1a and AML1b (both isoforms contain a DNA binding domain, but only AML1b has transcription regulatory domains) in mouse hematopoietic stem and progenitor cells and then tested the cells' ability to engraft in mice. AML1a-expressing cells engrafted better than unaltered cells and outgrew unaltered cells when transplanted as a mixture. AML1b-expressing cells, however, did not engraft. In vitro, AML1a-expressing cells grew more than AML1b-expressing cells, whereas differentiation was promoted in AML1b-expressing cells. To investigate whether the isoforms have the same effects in human cells, the researchers measured the amount of AML1a and AML1b mRNA (the template for protein production) made by progenitor cells in human cord blood. Although AML1b (together with AML1c, an isoform with similar characteristics) mRNA predominated in all the progenitor cell types, the relative abundance of AML1a was greatest in the stem and progenitor cells. Furthermore, forced expression of AML1a in these cells improved their ability to divide in vitro and to engraft in mice.
What Do These Findings Mean?
These findings indicate that AML1a expression increases the self-renewal capacity of hematopoietic stem and progenitor cells and consequently improves their ability to engraft in mice, whereas AML1b expression encourages the differentiation of these cell types. These activities are consistent with the expression patterns of the two isoforms in normal hematopoietic cells and in leukemic cells—the mutated AML made by many leukemic cells resembles AML1a. Because the AML1 isoforms were expressed at higher than normal levels in these experiments, the physiological relevance of these findings needs to be confirmed by showing that normal levels of AML1a and AML1b produce similar results. Nevertheless, these results suggest that manipulating the balance of AML1 isoforms made by hematopoietic cells might be useful clinically. In leukemia, a shift toward AML1b expression might slow the proliferation of leukemic cells and encourage their differentiation. Conversely, in cord blood transplantation, a shift toward AML1a expression might improve patient outcomes by expanding the stem and progenitor cell populations.
Additional Information.
Please access these Web sites via the online version of this summary at
Wikipedia has pages on hematopoiesis and hematopoietic stem cells (note: Wikipedia is a free online encyclopedia that anyone can edit; available in several languages)
The US National Cancer Institute has a fact sheet on bone marrow and peripheral blood stem cell transplantation (in English and Spanish) and information for patients and professionals on leukemia (in English)
The American Society of Hematology provides patient information about blood diseases, including information on bone marrow and stem cell transplantation
PMCID: PMC1868041  PMID: 17503961
2.  The leukemogenic t(8;21) fusion protein AML1-ETO controls ribosomal RNA genes and associates with nucleolar organizing regions at mitotic chromosomes 
Journal of cell science  2008;121(Pt 23):3981-3990.
RUNX1/AML1 is required for definitive hematopoiesis and is frequently targeted by chromosomal translocation in acute myeloid leukemias (AML). The t(8;21) related AML1-ETO fusion protein blocks differentiation of myeloid progenitors. Here, we show by immunofluorescence microscopy that during interphase, endogenous AML1-ETO localizes to nuclear microenvironments distinct from those containing native RUNX1/AML1 protein. At mitosis, we clearly detect binding of AML1-ETO to nucleolar organizing regions (NORs) in AML derived Kasumi-1 cells and binding of RUNX1/AML1 to NORs in Jurkat cells. Both RUNX1/AML1 and AML1-ETO occupy ribosomal DNA repeats during interphase, as well as interact with the endogenous RNA Pol I transcription factor UBF-1. Promoter cytosine methylation analysis indicates that RUNX1/AML1 binds to rDNA repeats that are more highly CpG methylated than those bound by AML1-ETO. Down-regulation by RNA interference reveals that RUNX1/AML1 negatively regulates rDNA transcription, while AML1-ETO is a positive regulator in Kasumi-1 cells. Taken together, our findings identify a novel role for the leukemia-related AML1-ETO protein in epigenetic control of cell growth through upregulation of RNA Pol I-mediated ribosomal gene transcription, consistent with the hyper-proliferative phenotype of myeloid cells in AML patients.
PMCID: PMC2904240  PMID: 19001502
acute myelogenous leukemia; Runx1; ribosomal DNA transcription; RNA polymerase I; UBF1; nucleolar organizing region
3.  An unusual case of splenomegaly and increased lactate dehydrogenase heralding acute myeloid leukemia with eosinophilia and RUNX1–MECOM fusion transcripts 
Leukemia Research Reports  2014;3(2):83-85.
We report the first case of acute myeloid leukemia (AML) with RUNX1–MECOM fusion transcripts, showing marked eosinophilia. A 63-year old man admitted in August 2013, had previously been observed in April 2013, because of persisting homogeneous splenomegaly and increased LDH, which were initially attributed to both minor β-thalassemia and previous acute myocardial infarction. However, based upon the retrospective analysis of clinical features combined with the documentation of both JAK2 V617F and c-KIT D816V mutations at AML diagnosis, an aggressive leukemic transformation with eosinophilia of a previously unrecognized myeloproliferative neoplasm, rather than the occurrence of de novo AML, may be hypothesized.
•We report the first case of AML with RUNX1–MECOM fusion transcripts and eosinophilia.•JAK2 V617F and c-KIT D816V mutations have been concurrently observed.•Leukemic transformation of a previously unrecognized MPN may be hypothesized.
PMCID: PMC4220014  PMID: 25379409
Acute myeloid leukemia; t(3;21)(q26;q22); RUNX1–MECOM; Eosinophilia; Splenomegaly; Myeloproliferative neoplasm
4.  Differences in Platelet Function In Patients with Acute Myeloid Leukaemia and Myelodysplasia Compared to Equally Thrombocytopenic Patients with Immune Thrombocytopenia 
Severe thrombocytopenia is a major risk factor for haemorrhage, and yet platelet function and bleeding risk at low platelet counts are poorly understood because of limitations of platelet function testing at very low platelet counts.
To examine and compare platelet function in severely thrombocytopenic patients with acute myeloid leukaemia (AML) or myelodysplasia (MDS) to patients with immune thrombocytopenia (ITP).
Whole blood flow cytometric measurement of platelet activation and platelet reactivity to agonists was correlated with the immature platelet fraction (IPF) and bleeding symptoms.
Compared with patients with ITP, patients with AML/MDS had smaller platelets, lower IPF, and substantially lower platelet surface expression of activated GPIIb/IIIa and GPIb both with and without addition of ex vivo ADP or TRAP. In both ITP and AML/MDS, increased platelet surface GPIb on circulating platelets and expression of activated GPIIb/IIIa and GPIb on ex vivo activated platelets correlated with a higher IPF. Whereas platelet reactivity was higher for AML/MDS patients with bleeding than those with no bleeding, platelet reactivity was lower for ITP patients with bleeding than those with no bleeding.
AML/MDS patients have lower in vivo platelet activation and ex vivo platelet reactivity than patients with ITP. The proportion of newly-produced platelets correlates with the expression of platelet surface markers of activation. These differences might contribute to differences in bleeding tendency between AML/MDS and ITP. This study is the first to define differences in platelet function between AML/MDS patients and ITP patients with equivalent degrees of thrombocytopenia.
PMCID: PMC3210015  PMID: 21920014
Autoimmunity; bleeding; flow cytometry; haemorrhage; thrombocytopenia; thrombopoiesis
5.  Molecular characterization of the rare translocation t(3;10)(q26;q21) in an acute myeloid leukemia patient 
In acute myeloid leukemia (AML), the MDS1 and EVI1 complex locus - MECOM, also known as the ecotropic virus integration site 1 - EVI1, located in band 3q26, can be rearranged with a variety of partner chromosomes and partner genes. Here we report on a 57-year-old female with AML who presented with the rare translocation t(3;10)(q26;q21) involving the MECOM gene. Our aim was to identify the fusion partner on chromosome 10q21 and to characterize the precise nucleotide sequence of the chromosomal breakpoint.
Cytogenetic and molecular-cytogenetic techniques, chromosome microdissection, next generation sequencing, long-range PCR and direct Sanger sequencing were used to map the chromosomal translocation.
Using a combination of cytogenetic and molecular approaches, we mapped the t(3;10)(q26;q21) to the single nucleotide level, revealing a fusion of the MECOM gene (3q26.2) and C10orf107 (10q21.2).
The approach described here opens up new possibilities in characterizing acquired as well as congenital chromosomal aberrations. In addition, DNA sequences of chromosomal breakpoints may be a useful tool for unique molecular minimal residual disease target identification in acute leukemia patients.
PMCID: PMC4113123  PMID: 25071866
AML; MECOM; Chromosomal microdissection; Next-generation sequencing; Molecular marker
6.  5′RUNX1-3′USP42 chimeric gene in acute myeloid leukemia can occur through an insertion mechanism rather than translocation and may be mediated by genomic segmental duplications 
Molecular Cytogenetics  2014;7(1):66.
The runt-related transcription factor 1 (RUNX1) gene is a transcription factor that acts as a master regulator of hematopoiesis and represents one of the most frequent targets of chromosomal rearrangements in human leukemias. The t(7;21)(p22;q22) rearrangement generating a 5′RUNX1-3′USP42 fusion transcript has been reported in two cases of pediatric acute myeloid leukemia (AML) and further in eight adult cases of myeloid neoplasms. We describe the first case of adult AML with a 5′RUNX1-3′USP42 fusion gene generated by an insertion event instead of chromosomal translocation.
Conventional and molecular cytogenetic analyses allowed the precise characterization of the chromosomal rearrangement and breakpoints identification. Gene expression analysis was performed by quantitative real-time PCR experiments, whereas bioinformatic studies were carried out for revealing structural genomic characteristics of breakpoint regions.
We identified an adult AML case bearing a ins(21;7)(q22;p15p22) generating a 5′RUNX1-3′USP42 fusion gene on der(21) chromosome and causing USP42 gene over-expression. Bioinformatic analysis of the genomic regions involved in ins(21;7)/t(7;21) showed the presence of interchromosomal segmental duplications (SDs) next to the USP42 and RUNX1 genes, that may underlie a non-allelic homologous recombination between chromosome 7 and 21 in AML.
We report the first case of a 5′RUNX1-3′USP42 chimeric gene generated by a chromosomal cryptic insertion in an adult AML patient. Our data revealed that there may be a pivotal role for SDs in this very rare but recurrent chromosomal rearrangement.
PMCID: PMC4189616  PMID: 25298786
Acute myeloid leukemia; Cancer genetics; Insertion event; Segmental duplications
7.  NPM1 Gene Type A Mutation in Bulgarian Adults with Acute Myeloid Leukemia: A Single-Institution Study 
Turkish Journal of Hematology  2014;31(1):40-48.
Objective: Mutations of the nucleophosmin (NPM1) gene are considered as the most frequent acute myeloid leukemia (AML)-associated genetic lesion, reported with various incidences in different studies, and type A (NPM1-A) is the most frequent type. However, since most series in the literature report on the features of all patients regardless of the type of mutation, NPM1-A(+) cases have not been well characterized yet. Therefore, we evaluated the prevalence of NPM1-A in Bulgarian AML patients and searched for an association with clinical and laboratory features.
Materials and Methods: One hundred and four adults (51 men, 53 women) were included in the study. NPM1-A status was determined using allele-specific reverse-transcription polymerase chain reaction with co-amplification of NPM1-A and β-actin and real-time quantitative TaqMan-based polymerase chain reaction. Patients received conventional induction chemotherapy and were followed for 13.2±16.4 months.
Results: NPM1-A was detected in 26 (24.8%) patients. NPM1-A mutation was detected in all AML categories, including in one patient with RUNX1-RUNX1T1. There were no differences associated with the NPM1-A status with respect to age, sex, hemoglobin, platelet counts, percentage of bone marrow blasts, splenomegaly, complete remission rates, and overall survival. NPM1-A(+) patients, compared to NPM1-A(-) patients, were characterized by higher leukocyte counts [(75.4±81.9)x109/L vs. (42.5±65.9)x109/L; p=0.049], higher frequency of normal karyotype [14/18 (77.8%) vs. 26/62 (41.9%); p=0.014], higher frequency of FLT3-ITD [11/26 (42.3%) vs. 8/77 (10.4%); p=0.001], and lower incidence of CD34(+) [6/21 (28.8%) vs. 28/45 (62.2%); p=0.017]. Within the FLT3-ITD(-) group, the median overall survival of NPM1-A(-) patients was 14 months, while NPM1-A(+) patients did not reach the median (p=0.10).
Conclusion: The prevalence of NPM1-A mutation in adult Bulgarian AML patients was similar to that reported in other studies. NPM1-A(+) patients were characterized by higher leukocyte counts, higher frequency of normal karyotypes and FLT3-ITD, and lower incidence of CD34(+), supporting the idea that the specific features of type A mutations might contribute to the general clinical and laboratory profile of NPM1(+) AML patients.
PMCID: PMC3996648  PMID: 24764728
Acute myeloid leukemia; NPM1 gene type A mutation; FLT3-ITD; allele-specific polymerase chain reaction
8.  Both SEPT2 and MLL are down-regulated in MLL-SEPT2 therapy-related myeloid neoplasia 
BMC Cancer  2009;9:147.
A relevant role of septins in leukemogenesis has been uncovered by their involvement as fusion partners in MLL-related leukemia. Recently, we have established the MLL-SEPT2 gene fusion as the molecular abnormality subjacent to the translocation t(2;11)(q37;q23) in therapy-related acute myeloid leukemia. In this work we quantified MLL and SEPT2 gene expression in 58 acute myeloid leukemia patients selected to represent the major AML genetic subgroups, as well as in all three cases of MLL-SEPT2-associated myeloid neoplasms so far described in the literature.
Cytogenetics, fluorescence in situ hybridization (FISH) and molecular studies (RT-PCR, qRT-PCR and qMSP) were used to characterize 58 acute myeloid leukemia patients (AML) at diagnosis selected to represent the major AML genetic subgroups: CBFB-MYH11 (n = 13), PML-RARA (n = 12); RUNX1-RUNX1T1 (n = 12), normal karyotype (n = 11), and MLL gene fusions other than MLL-SEPT2 (n = 10). We also studied all three MLL-SEPT2 myeloid neoplasia cases reported in the literature, namely two AML patients and a t-MDS patient.
When compared with normal controls, we found a 12.8-fold reduction of wild-type SEPT2 and MLL-SEPT2 combined expression in cases with the MLL-SEPT2 gene fusion (p = 0.007), which is accompanied by a 12.4-fold down-regulation of wild-type MLL and MLL-SEPT2 combined expression (p = 0.028). The down-regulation of SEPT2 in MLL-SEPT2 myeloid neoplasias was statistically significant when compared with all other leukemia genetic subgroups (including those with other MLL gene fusions). In addition, MLL expression was also down-regulated in the group of MLL fusions other than MLL-SEPT2, when compared with the normal control group (p = 0.023)
We found a significant down-regulation of both SEPT2 and MLL in MLL-SEPT2 myeloid neoplasias. In addition, we also found that MLL is under-expressed in AML patients with MLL fusions other than MLL-SEPT2.
PMCID: PMC2689242  PMID: 19445675
9.  Five distinct biological processes and 14 differentially expressed genes characterize TEL/AML1-positive leukemia 
BMC Genomics  2007;8:385.
The t(12;21)(p13;q22) translocation is found in 20 to 25% of cases of childhood B-lineage acute lymphoblastic leukemia (B-ALL). This rearrangement results in the fusion of ETV6 (TEL) and RUNX1 (AML1) genes and defines a relatively uniform category, although only some patients suffer very late relapse. TEL/AML1-positive patients are thus an interesting subgroup to study, and such studies should elucidate the biological processes underlying TEL/AML1 pathogenesis. We report an analysis of gene expression in 60 children with B-lineage ALL using Agilent whole genome oligo-chips (44K-G4112A) and/or real time RT-PCR.
We compared the leukemia cell gene expression profiles of 16 TEL/AML1-positive ALL patients to those of 44 TEL/AML1-negative patients, whose blast cells did not contain any additional recurrent translocation. Microarray analyses of 26 samples allowed the identification of genes differentially expressed between the TEL/AML1-positive and negative ALL groups. Gene enrichment analysis defined five enriched GO categories: cell differentiation, cell proliferation, apoptosis, cell motility and response to wounding, associated with 14 genes -RUNX1, TCFL5, TNFRSF7, CBFA2T3, CD9, SCARB1, TP53INP1, ACVR1C, PIK3C3, EGFL7, SEMA6A, CTGF, LSP1, TFPI – highlighting the biology of the TEL/AML1 sub-group. These results were first confirmed by the analysis of an additional microarray data-set (7 patient samples) and second by real-time RT-PCR quantification and clustering using an independent set (27 patient samples). Over-expression of RUNX1 (AML1) was further investigated and in one third of the patients correlated with cytogenetic findings.
Gene expression analyses of leukemia cells from 60 children with TEL/AML1-positive and -negative B-lineage ALL led to the identification of five biological processes, associated with 14 validated genes characterizing and highlighting the biology of the TEL/AML1-positive ALL sub-group.
PMCID: PMC2211320  PMID: 17956600
10.  Cytoplasmic Localization of Nucleophosmin in Bone Marrow Blasts of Acute Myeloid Leukemia Patients is not Completely Concordant with NPM1 Mutation and is not Predictive of Prognosis 
Cancer  2009;115(20):4737-4744.
NPM1 mutations are reported to predict a favorable prognosis in acute myeloid leukemia (AML) patients. Aberrant cytoplasmic localization of NPM protein is reported be a surrogate for NPM1 gene mutation.
Using immunohistochemical analysis (IHC), we assessed for NPM (clone 376) expression in formalin-fixed, formic acid-decalcified bone marrow biopsy specimens. DNA sequencing of the exon 12 of NPM1 gene was performed in 104 patients.
The study included 252 AML patients: 192 de novo AML, 33 AML following a myelodysplastic syndrome or chronic myelomonocytic leukemia, and 27 therapy-related AML. The median age was 62 years and 115 patients were ≤ 60 years old. All patients received intensive chemotherapy. Cytoplasmic NPM was detected in 59 of 252 (23%) patients, including 48 of 192 (25%) de novo AML and 33 of 94 (35%) with a normal karyotype. DNA sequencing identified NPM1 mutations in 30 of 38 cases with cytoplasmic NPM and 10 of 66 cases with nuclear NPM. Cytoplasmic NPM was associated with young patient age (p=0.024), FLT3/ITD (p=0.005), CD34- negative blasts (p<0.001), high peripheral blood blast counts (p=0.041), and high serum albumin level (p=0.028). No statistical differences in overall or event-free survival were found on the basis of NPM localization. Similar results were obtained in patients ≤ 60 years old with normal karyotype and wild-type FLT3 (p=0.768).
Immunohistochemical assessment for NPM localization did not predict prognosis in this patient cohort. The discordance between immunohistochemistry and DNA sequencing results indicates that DNA sequencing cannot be replaced by IHC assessment.
PMCID: PMC4199225  PMID: 19637342
AML; NPM1 mutation; immunohistochemical analysis; prognosis; FLT3/ITD
11.  Significance of Neuropilin-1 Expression in Acute Myeloid Leukemia 
Turkish Journal of Hematology  2013;30(3):300-306.
Objective: Neuropilin-1 is a vascular endothelial growth factor receptor that acts as a mediator of angiogenesis. Its importance in hematological malignancies such as acute myeloid leukemia (AML) remains to be elucidated. The aim of this study was to evaluate the significance of neuropilin-1 expression in AML patients by both flow cytometry and real-time polymerase chain reaction (PCR) in regard to its diagnostic and prognostic values.
Materials and Methods: Bone marrow aspirates of 44 patients with de novo AML and 12 relapsed AML patients were examined in this study. Ten subjects with nonhematological malignancy serving as the control group were also included.
Results: Neuropilin-1 expression by flow cytometry showed a highly significant increase in de novo and relapsed AML patients with a mean of 27.1±17.5% and 21.5±16.6%, respectively, compared to control group’s mean of 3.4±1.9%. A cut-off value of 6% was established as differentiating patients from the control group. By real-time PCR, no statistical significance was found in de novo and relapsed AML patients with a mean of 1.9±3.6 IU/L and 0.3±0.2 IU/L, respectively, compared to the control group’s mean of 0.3±0.1 IU/L. Neuropilin-1 surface expression by flow cytometry showed a significant correlation with total leukocyte count and a negative correlation with hemoglobin level in de novo AML patients. In relapsed AML patients, positive significant correlations were found with age, bone marrow blast percentage, and CD14. Neuropilin-1 mRNA level by real-time PCR showed a positive significant correlation with peripheral blood blast percentage and CD117 and a negative correlation with hemoglobin level in de novo AML patients. In relapsed patients, a positive correlation was found with lactate dehydrogenase.
Conclusion: Neuropilin-1 can be used as a tool for diagnosis and prognosis in AML patients.
Conflict of interest:None declared.
PMCID: PMC3878529  PMID: 24385810
Neuropilin-1; Acute myeloid leukemia
12.  Frequency of 11q23/MLL gene rearrangement in Egyptian childhood acute myeloblastic leukemia: Biologic and clinical significance 
South Asian Journal of Cancer  2014;3(4):206-208.
Molecular cytogenetic abnormalities involving 11q23 are among the most common cytogenetic abnormalities in acute myeloid leukemia (AML) patients.
Aim of the work:
we aimed to evaluate the frequency of MLL/AF9 fusion gene in de novo AML patients, its impact on clinical features, and its prognostic significance.
Patients and Methods:
Twenty-eight children patients with AML and 20 healthy controls were subjected to complete clinical examination and laboratory investigations including, complete hemogram and bone marrow (BM) examination. Diagnosis was based on FAB morphologic and immunophenotypic criteria. Detection of (MLL/AF9) fusion gene was assessed by dual color fluorescent in situ hybridization (FISH). Follow-up were carried out clinically and by blast count in BM, and response to therapy to detect the outcome of the disease.
The incidence of MLL-fusion gene MLL/AF9 in AML cases was about (6/28) (21%). Four patients with MLL/AF9 fusion gene were newly diagnosed, two cases were at relapse and no patient at remission showed positivity. As regard the clinical outcome, five out of six MLL positive cases died, three of them during induction and two during relapse. The FAB AML subtypes with MLL/AF9 fusion were one M2, three M4, and two M5.
MLL-fusion gene MLL/AF9 was found in about 21% of studied AML patients when assessed by FISH technique and this is of high clinical relevance as most of these abnormalities have been associated with poor prognosis.
PMCID: PMC4236697  PMID: 25422805
Acute myelobastic leukemia; 11q23/MLL gene; Dual color FISH
13.  MicroRNA-155 as an inducer of apoptosis and cell differentiation in Acute Myeloid Leukaemia 
Molecular Cancer  2014;13:79.
Acute myeloid leukaemia (AML) is characterised by the halt in maturation of myeloid progenitor cells, combined with uncontrolled proliferation and abnormal survival, leading to the accumulation of immature blasts. In many subtypes of AML the underlying causative genetic insults are not fully described. MicroRNAs are known to be dysregulated during oncogenesis. Overexpression of miR-155 is associated with some cancers, including haematological malignancies, and it has been postulated that miR-155 has an oncogenic role. This study investigated the effects of modulating miR-155 expression in human AML cells, and its mechanism of action.
Analysis of miR-155 expression patterns in AML patients found that Fms-like tyrosine kinase 3 (FLT3)-wildtype AML has the same expression level as normal bone marrow, with increased expression restricted to AML with the FLT3-ITD mutation. Induction of apoptosis by cytarabine arabinoside or myelomonocytic differentiation by 1,23-dihydroxyvitaminD3 in FLT3-wildtype AML cells led to upregulated miR-155 expression. Knockdown of miR-155 by locked nucleic acid antisense oligonucleotides in the FLT3-wildtype AML cells conferred resistance to cytarabine arabinoside induced apoptosis and suppressed the ability of cells to differentiate.
Ectopic expression of miR-155 in FLT3-wildtype AML cells led to a significant gain of myelomonocytic markers (CD11b, CD14 and CD15), increase in apoptosis (AnnexinV binding), decrease in cell growth and clonogenic capacity.
In silico target prediction identified a number of putative miR-155 target genes, and the expression changes of key transcription regulators of myeloid differentiation and apoptosis (MEIS1, GF1, cMYC, JARID2, cJUN, FOS, CTNNB1 and TRIB2) were confirmed by PCR. Assessment of expression of apoptosis-related proteins demonstrated a marked increase in cleaved caspase-3 expression confirming activation of the apoptosis cascade.
This study provides evidence for an anti-leukaemic role for miR-155 in human FLT3-wildtype AML, by inducing cell apoptosis and myelomonocytic differentiation, which is in contrast to its previously hypothesized role as an oncogene. This highlights the complexity of gene regulation by microRNAs that may have tumour repressor or oncogenic effects depending on disease context or tissue type.
PMCID: PMC4021368  PMID: 24708856
Acute Myeloid Leukaemia (AML); microRNA; miR-155; Apoptosis; Myeloid differentiation
14.  MDM4 Overexpressed in Acute Myeloid Leukemia Patients with Complex Karyotype and Wild-Type TP53 
PLoS ONE  2014;9(11):e113088.
Acute myeloid leukemia patients with complex karyotype (CK-AML) account for approximately 10–15% of adult AML cases, and are often associated with a poor prognosis. Except for about 70% of CK-AML patients with biallelic inactivation of TP53, the leukemogenic mechanism in the nearly 30% of CK-AML patients with wild-type TP53 has remained elusive. In this study, 15 cases with complex karyotype and wild-type TP53 were screened out of 140 de novo AML patients and the expression levels of MDM4, a main negative regulator of p53-signaling pathway, were detected. We ruled out mutations in genes associated with a poor prognosis of CK-AML, including RUNX1 or FLT3-ITD. The mRNA expression levels of the full-length of MDM4 (MDM4FL) and short isoform MDM4 (MDM4S) were elevated in CK-AML relative to normal karyotype AML (NK-AML) patients. We also explored the impact of MDM4 overexpression on the cell cycle, cell proliferation and the spindle checkpoint of HepG2 cells, which is a human cancer cell line with normal MDM4 and TP53 expression. The mitotic index and the expression of p21, BubR1 and Securin were all reduced following Nocodazole treatment. Moreover, karyotype analysis showed that MDM4 overexpression might lead to aneuploidy or polyploidy. These results suggest that MDM4 overexpression is related to CK-AML with wild-type TP53 and might play a pathogenic role by inhibiting p53-signal pathway.
PMCID: PMC4236138  PMID: 25405759
15.  Accelerated Telomere Shortening Precedes Development of Therapy-Related Myelodysplasia or Acute Myelogenous Leukemia After Autologous Transplantation for Lymphoma 
Journal of Clinical Oncology  2009;27(5):791-798.
Therapy-related myelodysplasia or acute myelogenous leukemia (t-MDS/AML) is a lethal complication of autologous hematopoietic stem-cell transplantation (aHCT) for Hodgkin's lymphoma (HL) and non-Hodgkin's lymphoma (NHL). Here, we investigated the hypothesis that accelerated telomere shortening after aHCT could contribute to the development of t-MDS/AML.
Patients and Methods
A prospective longitudinal cohort was constructed to investigate the sequence of cellular and molecular abnormalities leading to development of t-MDS/AML after aHCT for HL/NHL. This cohort formed the sampling frame for a nested case-control study to compare changes in telomere length in serial blood samples from patients who developed t-MDS/AML with matched controls who did not develop t-MDS/AML.
An initial increase in telomere length at day 100 after aHCT was followed by an accelerated telomere shortening in t-MDS/AML patients when compared with controls. These telomere alterations preceded the onset of t-MDS and were independent of other known risk factors associated with development of t-MDS/AML on multivariate analysis. Additionally, we observed reduced generation of committed progenitors in patients who developed t-MDS/AML, indicating that these telomere alterations were associated with reduced regenerative capacity of hematopoietic stem cells.
The development of t-MDS/AML after aHCT is associated with and preceded by markedly altered telomere dynamics in hematopoietic cells. Accelerated telomere loss in patients developing t-MDS/AML may reflect increased clonal proliferation and/or altered telomere regulation in premalignant cells. Genetic instability associated with shortened telomeres may contribute to leukemic transformation in t-MDS/AML.
PMCID: PMC2645091  PMID: 19124806
16.  Prognostic value of miR-96 in patients with acute myeloid leukemia 
Diagnostic Pathology  2014;9:76.
Aberrant expression of miRNA (miR)-96 is associated with tumorigenesis and tumor progression in several solid cancers. However, little is known about the expression and prognostic value of miR-96 in acute myeloid leukemia (AML). Therefore, the aim of this study was to investigate the correlation of miR-96 expression with clinicopathological features and prognosis of AML.
Real-time quantitative RT-PCR assay was performed to evaluate the expression levels of miR-96 in mononuclear cells from bone marrow or peripheral blood specimens in 86 patients with newly diagnosed AML.
Compared with normal controls, miR-96 expression was significantly downregulated in patients with newly diagnosed AML (P < 0.001). In analysis of 14 diagnosis/CR-paired samples, the expression level of miR-96 was found markedly elevated in patients after treatment than before (P < 0.001). Moreover, lower levels of miR-96 were associated with a higher white blood cell count, bone marrow blast count (P < 0.001 and 0.022, respectively), and lower hemoglobin and platelet count (P = 0.036 and 0.033, respectively). Although the low-expression group seemed to have a lower CR rate (53.85% vs 70.0%), there was no significant difference between the two groups (P = 0.213). The low-expression group had a lower relapse-free survival (RFS) (P = 0.038) and overall survival (OS) (P = 0.022) compared with the high-expression group during a median follow-up of 20 months.
Our data demonstrated that the expression of miR-96 was downregulated in newly diagnosed AML patients and associated with leukemic burden, as well as RFS and OS. This suggests that miR-96 detection might become a potential biomarker of prognosis and monitoring in AML.
Virtual slides
The virtual slide(s) for this article can be found here:
PMCID: PMC3975266  PMID: 24678958
miR-96; Acute myeloid leukemia; Real-time quantitative RT-PCR assay; Prognosis
17.  Multivariate and subgroup analyses of a randomized, multinational, phase 3 trial of decitabine vs treatment choice of supportive care or cytarabine in older patients with newly diagnosed acute myeloid leukemia and poor- or intermediate-risk cytogenetics 
BMC Cancer  2014;14:69.
Compared with younger patients, older adults with acute myeloid leukemia (AML) generally have poorer survival outcomes and less benefit from clinical trials. A recent phase 3 trial demonstrated a trend toward improved overall survival (OS) with decitabine, a hypomethylating agent, compared with treatment choice of either cytarabine or supportive care (7.7 months, 95% CI: 6.2–9.2 vs 5.0 months, 95% CI: 4.3–6.3, respectively) in older adults with newly diagnosed AML. The current analyses investigated prognostic factors for outcomes in this trial and examined OS and responses in prespecified subgroups.
A multivariate Cox proportional hazards model was used to investigate effects of demographic and baseline characteristics, including age, sex, cytogenetic risk, AML type, ECOG Performance Status, geographic region, bone marrow blasts, platelets, and white blood cells on OS, based on mature data. Similar analyses were conducted with a logistic regression model to predict response rates. Prespecified subgroup analyses were performed for OS and response rates, also using mature data.
Patient characteristics that appeared to negatively influence OS included more advanced age (hazard ratio [HR] 1.560 for ≥75 vs <70 years; p = 0.0010), poorer performance status at baseline (HR 0.771 for 0 or 1 vs 2; p = 0.0321), poor cytogenetics (HR 0.699 for intermediate vs poor; p = 0.0010), higher bone marrow blast counts (HR 1.355 for >50% vs ≤50%; p = 0.0045), low baseline platelet counts (HR 0.775 for each additional 100 × 109/L; p = 0.0015), and high white blood cell counts (HR 1.256 for each additional 25 × 109/L; p = 0.0151). Regarding geographic regions, patients from Western Europe had the longest median OS. Response rates favored decitabine for all subgroups investigated, including patients ≥75 years (odds ratio 5.94, p = 0.0006).
Response to decitabine in AML is associated with known prognostic factors related to both patient demographics and disease characteristics.
Trial registration identifier NCT00260832
PMCID: PMC3928608  PMID: 24498872
Decitabine; Acute Myelocytic Leukemia; Elderly; Treatment
18.  AML1/ETO Oncoprotein Is Directed to AML1 Binding Regions and Co-Localizes with AML1 and HEB on Its Targets 
PLoS Genetics  2008;4(11):e1000275.
A reciprocal translocation involving chromosomes 8 and 21 generates the AML1/ETO oncogenic transcription factor that initiates acute myeloid leukemia by recruiting co-repressor complexes to DNA. AML1/ETO interferes with the function of its wild-type counterpart, AML1, by directly targeting AML1 binding sites. However, transcriptional regulation determined by AML1/ETO probably relies on a more complex network, since the fusion protein has been shown to interact with a number of other transcription factors, in particular E-proteins, and may therefore target other sites on DNA. Genome-wide chromatin immunoprecipitation and expression profiling were exploited to identify AML1/ETO-dependent transcriptional regulation. AML1/ETO was found to co-localize with AML1, demonstrating that the fusion protein follows the binding pattern of the wild-type protein but does not function primarily by displacing it. The DNA binding profile of the E-protein HEB was grossly rearranged upon expression of AML1/ETO, and the fusion protein was found to co-localize with both AML1 and HEB on many of its regulated targets. Furthermore, the level of HEB protein was increased in both primary cells and cell lines expressing AML1/ETO. Our results suggest a major role for the functional interaction of AML1/ETO with AML1 and HEB in transcriptional regulation determined by the fusion protein.
Author Summary
Acute myeloid leukemias (AML) are a group of hematologic malignancies initiated by chromosomal abnormalities that often give origin to oncogenic proteins with transcriptional regulatory functions. These aberrant transcription factors bind to specific sequences on DNA and influence the activity of adjacent genes. The result is that leukemic blasts display abnormalities in their gene expression programs, which are ultimately responsible for the malignant phenotype. In this study, genome-wide approaches were exploited not only to identify target genes, but also to discover interactions among different transcription factors, with the aim of defining disease-linked regulatory networks. We performed a detailed analysis of the DNA binding pattern of an oncogenic transcription factor, AML1/ETO, which is responsible for approximately 10–15% of AML. We identified a specific signature, which is characterized by the presence of binding regions for AML1/ETO and for other transcription factors, AML1 and HEB, and found that the DNA binding pattern of AML1 and HEB is significantly affected in cells expressing AML1/ETO. Our results, therefore, describe genes regulated by AML1/ETO and demonstrate that this oncogenic protein can significantly interfere with the function of other transcriptional regulators.
PMCID: PMC2577924  PMID: 19043539
19.  Integrative analysis of RUNX1 downstream pathways and target genes 
BMC Genomics  2008;9:363.
The RUNX1 transcription factor gene is frequently mutated in sporadic myeloid and lymphoid leukemia through translocation, point mutation or amplification. It is also responsible for a familial platelet disorder with predisposition to acute myeloid leukemia (FPD-AML). The disruption of the largely unknown biological pathways controlled by RUNX1 is likely to be responsible for the development of leukemia. We have used multiple microarray platforms and bioinformatic techniques to help identify these biological pathways to aid in the understanding of why RUNX1 mutations lead to leukemia.
Here we report genes regulated either directly or indirectly by RUNX1 based on the study of gene expression profiles generated from 3 different human and mouse platforms. The platforms used were global gene expression profiling of: 1) cell lines with RUNX1 mutations from FPD-AML patients, 2) over-expression of RUNX1 and CBFβ, and 3) Runx1 knockout mouse embryos using either cDNA or Affymetrix microarrays. We observe that our datasets (lists of differentially expressed genes) significantly correlate with published microarray data from sporadic AML patients with mutations in either RUNX1 or its cofactor, CBFβ. A number of biological processes were identified among the differentially expressed genes and functional assays suggest that heterozygous RUNX1 point mutations in patients with FPD-AML impair cell proliferation, microtubule dynamics and possibly genetic stability. In addition, analysis of the regulatory regions of the differentially expressed genes has for the first time systematically identified numerous potential novel RUNX1 target genes.
This work is the first large-scale study attempting to identify the genetic networks regulated by RUNX1, a master regulator in the development of the hematopoietic system and leukemia. The biological pathways and target genes controlled by RUNX1 will have considerable importance in disease progression in both familial and sporadic leukemia as well as therapeutic implications.
PMCID: PMC2529319  PMID: 18671852
20.  Pretreatment long interspersed element (LINE)-1 methylation levels, not early hypomethylation under treatment, predict hematological response to azacitidine in elderly patients with acute myeloid leukemia 
OncoTargets and therapy  2013;6:741-748.
Epigenetic modulations, including changes in DNA cytosine methylation, are implicated in the pathogenesis and progression of acute myeloid leukemia (AML). Azacitidine is a hypomethylating agent that is incorporated into RNA as well as DNA. Thus, there is a rationale to its use in patients with AML. We determined whether baseline and/or early changes in the methylation of long interspersed element (LINE)-1 or CDH13 correlate with bone marrow blast clearance, hematological response, or survival in patients with AML treated with azacitidine.
An open label, phase I/II trial was performed in 40 AML patients (median bone marrow blast count was 42%) unfit for intensive chemotherapy treated with azacitidine 75 mg/m2/day subcutaneously for 5 days every 4 weeks. Bone marrow mononuclear cell samples were taken on day 0 (pretreatment) and day 15 during the first treatment cycle; LINE-1 and CDH13 methylation levels were quantified by methylation-specific, semiquantitative, real-time polymerase chain reaction.
Treatment with azacitidine significantly reduced LINE-1 but not CDH13 methylation levels over the first cycle (P < 0.0001). Absolute LINE-1 methylation levels tended to be lower on day 0 (P = 0.06) and day 15 of cycle 1 (P = 0.03) in patients who went on to achieve subsequent complete remission, partial remission or hematological improvement versus patients with stable disease. However, the decrease in LINE-1 methylation over the first treatment cycle did not correlate with subsequent response (P = 0.31). Baseline methylation levels of LINE-1 or CDH13 did not correlate with disease-related prognostic factors, including cytogenetic risk, relapsed/refractory AML, or presence of NPM1 or FLT3 mutations. No correlation was observed between LINE-1 or CDH13 methylation levels and overall survival.
Analysis of baseline LINE-1 methylation levels may help identify elderly AML patients who are most likely to respond to azacitidine therapy.
PMCID: PMC3699298  PMID: 23836986
DNA methylation; acute myeloid leukemia; azacitidine; clinical response; CDH13; LINE-1 methylation
21.  Successful management of acute myeloid leukemia transformed from chronic myelomonocytic leukemia in the elderly by a combination regimen of decitabine and cytarabine, aclarubicin and granulocyte colony-stimulating factor: A case report 
Oncology Letters  2015;9(3):1217-1220.
Despite advances in the treatment of acute myeloid leukemia (AML) in recent years, the outcome of elderly AML patients with antecedent hematological disorders remains unsatisfactory. The present study describes a case of complete remission in an elderly patient with AML transformed from chronic myelomonocytic leukemia (CMML) and the treatment of the case with decitabine in combination with cytarabine, aclarubicin and granulocyte colony-stimulating factor (CAG). A 70-year-old male was admitted with fever, pruritus and weakness that had been apparent for two weeks, and a two-year history of monocytosis (22.5–27.0%). Further examinations revealed a hemoglobin level of 106 g/l, a white blood cell count of 39.52×109/l, a platelet count of 81×109/l, Y chromosome loss and uniparental disomy on chromosomes 4q, 2q and 19p. The patient was diagnosed with AML transformed from CMML, with cytogenetic anomalies. A combination regimen of decitabine and CAG was administered. Subsequent to one cycle, the patient achieved complete remission. The patient was then followed up with three courses of the same regimen and achieved clinical remission, with no evidence of AML relapse. The present study suggests that a combination of low-dose decitabine and CAG may offer a novel and potentially effective treatment regimen for elderly AML patients.
PMCID: PMC4315126  PMID: 25663885
acute myeloid leukemia; chronic myeloid leukemia; decitabine; cytarabine; aclarubicin and granulocyte colony-stimulating factor; single nucleotide polymorphism
22.  Characteristics of hematologic malignancies with coexisting t(9;22) and inv(16) chromosomal abnormalities 
Blood research  2014;49(1):22-28.
The coexistence of t(9;22)(q34;q11.2) and inv(16)(p13q22) chromosomal abnormalities is extremely uncommon, and only a small number of such cases have been reported. Here, we characterized 7 cases of hematologic malignancy exhibiting t(9;22) and inv(16) coexistence.
We reviewed the cytogenetic data for hematologic malignancies treated at the Catholic Blood and Marrow Transplantation Center between January 2004 and June 2013. We identified 7 cases exhibiting t(9;22) and inv(16) coexistence. In addition, we analyzed mutations in the IKZF1, NPM1, FLT3, N-RAS, K-RAS, c-KIT, and TP53 genes.
Four cases of chronic myelogenous leukemia (CML; 1 chronic phase, 2 accelerated phase, and 1 blast phase) and 3 cases of acute myeloid leukemia (AML; 1 de novo and 2 therapy-related) were identified. The percentages of circulating blasts and bone marrow eosinophils were higher in AML cases than in CML cases (53% vs. 5% and 30% vs. 5.5%, respectively). The proportions of each chromosomal abnormality were used along with follow-up karyotyping results to identify secondary changes. In BCR/ABL, a p210 fusion transcript was associated with CML, whereas a p190 fusion transcript was associated with AML. One patient with AML harbored 2 mutations: c-KIT D816V and TP53 E11Q. All patients except 1 with CML blast phase sustained clinical remission after treatment, which included an imatinib mesylate regimen.
This study shows that observations of bone marrow morphology, initial and follow-up cytogenetic studies, and karyotyping of BCR/ABL1 and CBFB/MYH11 provide valuable information for characterizing hematologic malignancies exhibiting t(9;22) and inv(16) coexistence.
PMCID: PMC3974952  PMID: 24724063
Chronic myelogenous leukemia; Acute myeloid leukemia; t(9;22); BCR/ABL1; inv(16); CBFB/MYH11
23.  Correlations of hematological parameters with bone marrow findings in chronic lymphoproliferative disorders associated with hepatitis viruses 
Journal of Medicine and Life  2013;6(4):464-471.
Background. Hepatitis B and C viruses’ infections are often associated with hematological disorders in evolution, suggesting that these viruses have a tropism for peripheral blood and/or bone marrow cells.
Aim. To analyze the hematological parameters and bone marrow findings in a group of patients diagnosed with chronic lymphoproliferative disorders (CLD) and hepatitis viruses B, C, D infections, which were included in the research grant (acronym LIMFO-VIR) between December 2007 and May 2010 in the Hematology Department of the Emergency University Hospital of Bucharest.
Methods and results. Patients were diagnosed by using immunopathology according to the WHO criteria. The analyzed group included 42 patients (both sexes), with the mean age of 60,35 years. The most frequent hematologic disease was non-Hodgkin’s lymphoma 30/42 (71,42%), followed by chronic lymphocytic leukemia (16,66%) and Hodgkin’s lymphoma (7,14%). Hepatitis viruses were distributed: 17/42 (40,47%) patients with HBV, 22/42 (52,38%) with HCV and 3/42 (7,14%) had a double/triple association of viruses. Most of the patients had an indolent type of disease - 27/42 (64,28%), whereas 15/42 (35,71%) had an aggressive one, pattern found both in the HBV and HCV infected groups. An abnormal bone marrow result was revealed in 32/42 (76,19%) patients, 19 (59,37%) of them being HCV infected. Myelodysplasia was found in 6/42(14,28%) patients, the majority being HCV infected, all having an indolent form of CLD. The antiviral therapy did not influence the hematological parameters (no significant differences were found between the groups with/without an antiviral therapy).
Discussions. Patients with hepatitis virus infections may associate neutropenia and thrombocytopenia; the mechanisms are thought to involve hypersplenism, autoimmune processes and antiviral therapy. We excluded the influence of chemotherapy, as the study was performed before the treatment. In our group, patients whether HBV or HCV infected, presented an isolated cytopenia. The abnormal bone marrow cellularity (increased or decreased) and dysplasia were found especially in the HCV group. There are studies showing no association between myelodysplasia and hepatitis viruses; others found a strong relation of these. One of the mechanisms of myelodysplasia could be a dysregulation of the immune system.
Conclusions. Bone marrow/peripheral blood features correlate with the type of viral infection and HCV is more prone to develop additional hematological changes than HBV. The degree of bone marrow involvement by CLDs influences these features. We considered mandatory to perform a bone marrow analysis at the diagnosis of CLDs to stage and to establish if other bone marrow changes were present, a crucial aspect for therapy and outcome of the disease. The association between the hepatitis viruses – myelodysplasia- autoimmunity seems to have a role in the lymphoproliferative disorders etiology.
Abbreviations: CLD – chronic lymphoproliferative disorders; NHL- non-Hodgkin’s lymphoma, CLL- chronic lymphocytic leukemia, HL- Hodgkin’s lymphoma, MDS – myelodysplastic syndrome, AML – acute myeloid leukemia
PMCID: PMC4034312  PMID: 24868264
hepatitis viruses; chronic lymphoproliferative disorders; myelodysplasia; cytopenia
24.  Myeloid leukemia with t(7;21)(p22;q22) and 5q deletion 
Oncology Reports  2013;30(4):1549-1552.
The rare but recurrent RUNX1-USP42 fusion gene is the result of a t(7;21)(p22;q22) chromosomal translocation and has been described in 6 cases of acute myeloid leukemia (AML) and one case of refractory anemia with excess of blast. In the present study, we present the molecular genetic analysis and the clinical features of a t(7;21)(p22;q22)-positive AML case. PCR amplified two RUNX1-USP42 cDNA fragments but no reciprocal USP42-RUNX1 fragment indicating that the RUNX1-USP42 is the leukemogenic fusion gene. Sequencing of the two amplified fragments showed that exon 6 or exon 7 of RUNX1 (accession number NM_001754 version 3) was fused to exon 3 of USP42 (accession number NM_032172 version 2). The predicted RUNX1-USP42 fusion protein would contain the Runt homology domain (RHD), which is responsible for heterodimerization with CBFB and for DNA binding, and the catalytic UCH (ubiquitin carboxyl terminal hydroxylase) domain of the USP42 protein. The bone marrow cells in the present case also had a 5q deletion, and it was revealed that 5 out of the 8 reported cases (including the present case) with t(7;21)(p22;q22)/RUNX1-USP42 also had cytogenetic abnormalities of 5q. The fact that t(7;21) and 5q- occur together much more often than chance would allow seems to be unquestionable, although the pathogenetic connection between the two aberrations remains unknown.
PMCID: PMC3810351  PMID: 23877199
acute myeloid leukemia; cytogenetic; t(7;21)(p22;q22); 5q aberration; RUNX1; USP42; fusion gene
25.  Chromosomal Minimal Critical Regions in Therapy-Related Leukemia Appear Different from Those of De Novo Leukemia by High-Resolution aCGH 
PLoS ONE  2011;6(2):e16623.
Therapy-related acute leukemia (t-AML), is a severe complication of cytotoxic therapy used for primary cancer treatment. The outcome of these patients is poor, compared to people who develop de novo acute leukemia (p-AML). Cytogenetic abnormalities in t-AML are similar to those found in p-AML but present more frequent unfavorable karyotypes depending on the inducting agent. Losses of chromosome 5 or 7 are observed after alkylating agents while balanced translocations are found after topoisomerase II inhibitors. This study compared t-AML to p-AML using high resolution array CGH in order to find copy number abnormalities (CNA) at a higher resolution than conventional cytogenetics. More CNAs were observed in 30 t-AML than in 36 p-AML: 104 CNAs were observed with 63 losses and 41 gains (mean number 3.46 per case) in t-AML, while in p-AML, 69 CNAs were observed with 32 losses and 37 gains (mean number of 1.9 per case). In primary leukemia with a previously “normal” karyotype, 18% exhibited a previously undetected CNA, whereas in the (few) t-AML with a normal karyotype, the rate was 50%. Several minimal critical regions (MCRs) were found in t-AML and p-AML. No common MCRs were found in the two groups. In t-AML a 40kb deleted MCR pointed to RUNX1 on 21q22, a gene coding for a transcription factor implicated in frequent rearrangements in leukemia and in familial thrombocytopenia. In de novo AML, a 1Mb MCR harboring ERG and ETS2 was observed from patients with complex aCGH profiles. High resolution cytogenomics obtained by aCGH and similar techniques already published allowed us to characterize numerous non random chromosome abnormalities. This work supports the hypothesis that they can be classified into several categories: abnormalities common to all AML; those more frequently found in t-AML and those specifically found in p-AML.
PMCID: PMC3038855  PMID: 21339820

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