Activation of expression of p15, p73 and E-cadherin in myeloid leukemia cells by different concentrations of 5-aza-2'-deoxycytidine

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Caractérisation de l'oncogène MLF1 (Myeloid Leukemia Factor 1)

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Activation of expression of p15, p73 and E-cadherin in myeloid leukemia cells by different concentrations of 5-aza-2'-deoxycytidine

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Caractérisation de l'oncogène MLF1 (Myeloid Leukemia Factor 1)

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Inter-Laboratory Evaluation of a Next-Generation Sequencing Panel for Acute Myeloid Leukemia

INTRODUCTION: Acute myeloid leukemia (AML) is a heterogeneous clonal disorder often associated with dismal overall survival. The clinical diversity of AML is reflected in the range of recurrent somatic mutations in several genes, many of which have a prognostic and therapeutic value. Targeted next-generation sequencing (NGS) of these genes has the potential for translation into clinical practice. In order to assess this potential, an inter-laboratory evaluation of a commercially available AML gene panel across three diagnostic centres in the UK and Ireland was performed.

METHODS: DNA from six AML patient samples was distributed to each centre and processed using a standardised workflow, including a common sequencing platform, sequencing chips and bioinformatics pipeline. A duplicate sample in each centre was run to assess inter- and intra-laboratory performance.

RESULTS: An average sample read depth of 2725X (range 629-5600) was achieved using six samples per chip, with some variability observed in the depth of coverage generated for individual samples and between centres. A total of 16 somatic mutations were detected in the six AML samples, with a mean of 2.7 mutations per sample (range 1-4) representing nine genes on the panel. 15/16 mutations were identified by all three centres. Allelic frequencies of the mutations ranged from 5.6 to 53.3 % (median 44.4 %), with a high level of concordance of these frequencies between centres, for mutations detected.

CONCLUSION: In this inter-laboratory comparison, a high concordance, reproducibility and robustness was demonstrated using a commercially available NGS AML gene panel and platform.

Emergency emicolectomy for intestinal primary Aspergillosis in acute myeloid leukemia

ntestinal aspergillosis is an infection with a very high death rate especially in leukemic patients. Here we describe a case of a 46 years old woman with acute myeloid leukemia (LAM M5) who developed intestinal primary aspergillosis. This patient was diagnosed with LAM M5 through bone marrow aspiration and bone biopsy in March 2004. Symptoms of the disease were slight persistent fever, weight loss, asthenia, anemia, thrombocytopenia,and leukocytosis with high number of blasts in peripheral blood. After induction chemotherapy with ICE (Ifosfamide, Carboplatin, Etoposide), she developed neutropenia and high fever without apparent infective foci. She was treated with empiric antibiotic therapy, nevertheless she developed an intense diarrhea and ileo-cecal distention. Diagnostic exams didn’t show signs of a focal lesion. Despite the change in antibiotic treatment and the transfusions of granulocytes and blood cells, the patient developed extremely critical conditions with persistence of neutropenia and abdominal distention. A surgical treatment was decided at the time. We treated the patient with a two steps surgical procedure. The first step was a right abdominal ileostomy followed by improvement of general conditions and then the second step a right colectomy. The histological morphology confirmed necrotizing colitis with Aspergillus ife. At that time , treatment with voriconazole was started. The general conditions of the patient improved rapidly and we were able to treat the patient with other medical anti-leukemic therapies. The patient is now cured and in healthy state. We obtained a good clinical result as only in other few cases described in literature.

Molecular and functional characterization of the interplay between malignant and stromal cells in acute myeloid leukemia and myelodysplastic syndrome

In this thesis, we studied the cross-talk between malignant cells and stromal cells, with the aim to elucidate the respective contribution to myeloid neoplasm onset and progression. First, we characterized and compared mesenchymal stromal cells (MSCs) isolated from myelodysplastic syndrome (MDS-MSCs) and acute myeloid leukemia (AML-MSCs) patients. We demonstrated that, despite some unaltered functions, patient-derived MSCs show also intrinsic, distinct functional abnormalities, which could all potentially favor a leukemia-protective bone marrow (BM) niche in vivo. Second, we investigated the ability of AML cells to modulate the AML-MSC functions. In a GEP-screening, we found that 40% of BM-derived AML samples show a higher IFN-γ expression, compared to the mean IFN-γ expression in healthy BM-derived cells. We demonstrated that in co-culture experiments, IFN-γ+ AML cells modify AML-MSC gene expression and function, inducing the up-regulation of IDO1, and consequently the generation of T regulatory cells. Finally, we wondered if the transcriptome of stromal cells could be influenced by the hematopoietic-specific alterations, i.e. Dnmt3a and Asxl1 mutations, which occur early in MDS/AML patients. We found that Dnmt3a- and Asxl1-null BM cells, when transplanted in wild-type mice, induce profound and deletion-specific modifications in the transcriptome of wild-type BM stromal cells, suggesting the ability of Dnmt3a- and Asxl1-null BM cells to shape the niche. Furthermore, we compared the transcriptome of wild-type BM stromal cells, obtained from transplantation experiments, with that of MSCs isolated from low-risk MDS patients with DNMT3A and ASXL1 mutations, and we highlighted some common modifications, which could be potentially relevant for human disease and specific for DNMT3A/ASXL1 mutations. In conclusion, this thesis pointed out that there is a bi-directional cross-talk, in which stromal cells can influence malignant cells, and in turn malignant/pre-malignant cells can alter stromal cell gene expression and function. Both mechanisms could potentially contribute to the pathogenesis of myeloid malignancies.

Exploring novel targeted therapeutic strategies against Acute Myeloid Leukemia cells based on inhibition of bromodomain proteins and CDC20 activity

Acute myeloid leukemia (AML) is a haematological malignancies arising from the accumulation of undifferentiated myeloid progenitors with an uncontrolled proliferation. The genomic landscape of AML revealed that the disease is characterized by high level of heterogeneity and is subjected to clonal evolution driven by selective pressure of chemotherapy. In this study, we investigated the therapeutic effects of the inhibition of BRD4 and CDC20 in vitro and ex vivo. We demonstrated that inhibition of BRD4 with GSK1215101A in AML cell lines was effective under hypoxia. It induced the activation of antioxidant response both, at transcriptomic and metabolomic levels, driven by enrichment of NRF2 pathway under normoxic and hypoxic condition. Moreover, the combined treatment with Omaveloxolone, a drug inducing NRF2 activation and NF-κB inhibition, potentiated the effects on apoptosis and colony forming capacity of stem progenitor cells. Lastly, gene expression profiling data revealed that combination treatment induced major changes in genes related to cell cycle, together with enrichment of cell differentiation pathways and negative regulation of WNT, in normoxia and hypoxia. Regarding CDC20, we observed its up-regulation in AML patients. Treatment with two different inhibitors, Apcin and proTAME, was effective in primary AML cells and in AML cell lines, through induction of apoptosis and mitotic arrest. The lack of correlation between proliferation markers and CDC20 levels in AML cell subpopulations supports the idea of alternative CDC20 functions, independent from its essential role during mitosis. CDC20-KD experiments conducted in AML cell lines revealed a mild effect on apoptosis induction, but no significant change in cell cycle progression. In summary, these results allowed the identification of a new strategy combination to improve the effects of BRD4 inhibition on LSC residing in the BM hypoxic niche, and provide some new evidence regarding the potential role of CDC20 as a new target for AML treatment.

Dissecting and resetting SETD2/H3K36ME3 deficiency in chronic myeloid leukemia

Chronic myeloid leukemia (CML) is characterized by the presence of the BCR::ABL1 fusion gene, leading to a constitutively active tyrosine kinase that drives the disease. Genomic instability is a hallmark of CML, contributing to disease progression and treatment resistance. A study identified SETD2, a histone methyltransferase, as frequently dysfunctional in advanced-phase CML, resulting in reduced trimethylation of Histone H3 at lysine 36 (H3K36Me3). This loss is associated with poor prognosis and increased genetic instability. Investigations revealed that SETD2 dysfunction is caused by post-translational modifications mediated by Aurora kinase A and MDM2, leading to proteasome-mediated degradation. Aurora kinase A phosphorylates SETD2, while MDM2 ubiquitinates it, targeting it for degradation. Inhibition of MDM2 and Aurora kinase A restored SETD2 expression and activity, suggesting potential therapeutic targets. Loss of SETD2 and H3K36Me3 impairs DNA repair mechanisms, favoring error-prone repair pathways over faithful ones, exacerbating genetic instability. Reintroduction of SETD2 into deficient cells restored DNA repair pathways, preserving genomic integrity. Analysis of CD34+ progenitor cells from CML patients showed reduced SETD2 levels compared to healthy individuals, correlating with decreased clonogenic capacity. Notably, SETD2 loss is not detectable at diagnosis but emerges during disease progression, indicating its role as an early indicator of CML advancement. Therapeutically, inhibitors targeting Aurora kinase A, MDM2, and the proteasome showed efficacy in cells expressing SETD2, particularly in those with low SETD2 levels. Proteasome inhibitors induced apoptosis and DNA damage in SETD2-deficient cells, highlighting their potential for CML treatment. In conclusion, SETD2 acts as a tumor suppressor in CML, with its dysfunction contributing to genetic instability and disease progression. Targeting the mechanisms of SETD2 loss presents promising therapeutic avenues for controlling CML proliferation and restoring genomic integrity.

Characterization of myeloid or lymphoid acute leukemia by a chemiluminescence assay: Comparison with immunocytochemistry using an antimyeloperoxidase antibody

A simple and sensitive chemiluminescence assay for the demonstration of the activity of intracellular myeloperoxidase (MPO) is described, which is useful for the distinction between myeloid and lymphoid commitment in blasts from acute leukemia patients. When the cut-off point was settled at 13 mV of chemiluminescence all cases of acute myeloid leukemia (AML) were distinguished from those of acute lymphoid leukemia. In addition, this technique was able to demonstrate MPO activity in AML poorly differentiated (FAB-M0) which usually does not stain for MPO in classical cytochemistry preparations and could be negative also by immunocytochemistry with anti-MPO monoclonal antibody. Therefore the method here described presented a higher sensitivity than the immunocytochemistry procedure with anti-MPO.

ABO genotyping in leukemia patients reveals new ABO variant alleles

The ABO blood group is the most important blood group system in transfusion medicine and organ transplantation. To date, more than 160 ABO alleles have been identified by molecular investigation. Almost all ABO genotyping studies have been performed in blood donors and families and for investigation of ABO subgroups detected serologically. The aim of the present study was to perform ABO genotyping in patients with leukemia. Blood samples were collected from 108 Brazilian patients with chronic myeloid leukemia (N = 69), chronic lymphoid leukemia (N = 13), acute myeloid leukemia (N = 15), and acute lymphoid leukemia (N = 11). ABO genotyping was carried out using allele specific primer polymerase chain reaction followed by DNA sequencing. ABO*001 was the most common allele found, followed by ABO*022 and by ABO*A103. We identified 22 new ABO*(variants) in the coding region of the ABO gene in 25 individuals with leukemia (23.2%). The majority of ABO variants was detected in O alleles (15/60.0%). In 5 of 51 samples typed as blood group O (9.8%), we found non-deletional ABO*O alleles. Elucidation of the diversity of this gene in leukemia and in other diseases is important for the determination of the effect of changes in an amino acid residue on the specificity and activity of ABO glycosyltransferases and their function. In conclusion, this is the first report of a large number of patients with leukemia genotyped for ABO. The findings of this study indicate that there is a high level of recombinant activity in the ABO gene in leukemia patients, revealing new ABO variants.

The CEBPA gene is down-regulated in acute promyelocytic leukemia and its upstream promoter, but not the core promoter, is highly methylated

impairment of CCAAT Enhancer Binding Protein alpha (CEBPA) function is a common finding in acute myeloid leukemia; nevertheless, its relevance for acute promyelocytic leukemia pathogenesis is unclear. We analyzed the expression and assessed the methylation status of the core and upstream promoters of CEBPA in acute promyelocytic leukemia at diagnosis. Patients with acute promyelocytic leukemia (n=18) presented lower levels of CEBPA expression compared to healthy controls (n=5), but higher levels than those in acute myeloid leukemia with t(8;21) (n=9) and with inv(16) (n=5). Regarding the core promoter, we detected no methylation in 39 acute promyelocytic leukemia samples or in 8 samples from controls. In contrast, analysis of the upstream promoter showed methylation in 37 of 39 samples, with 17 patients showing methylation levels over 30%. Our results corroborate data obtained in animal models showing that CEBPA is down-regulated in acute promyelocytic leukemia stem cells and suggest that epigenetic mechanisms may be involved.

Cytogenetic Instability in Childhood Acute Lymphoblastic Leukemia Survivors

Contemporary anticancer therapies have largely improved the outcome for children with cancer, especially for Acute Lymphoblastic Leukemia (ALL). Actually, between 78% and 85% of patients achieve complete remission and are alive after 5 years of therapy completion. However, as cure rates increase, new concerns about the late effects of genotoxic treatment emerge, being the risk of developing secondary neoplasias, the most serious life-threatening rising problem. In the present paper, we describe and review the cytogenetic findings in peripheral lymphocytes from ALL survivors, and discuss aspects associated to the occurrence of increased chromosome rearrangements in this growing cohort.

The role of p38 mitogen-activated protein kinase in serum-induced leukemia inhibitory factor secretion by bone marrow stromal cells from pediatric myelodysplastic syndromes

Stromal cells from pediatric myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) associated with MDS(MDS-AML) present high expression of leukemia inhibitor factor (LIF). We demonstrated using mitogen-activated protein kinase ( MAPK) inhibitors that in stromal cells from pediatric MDS and MDS-AML, p38MAPK was critical in serum-induced secretion of LIF. The serum induction of phosphorylated p38MAPK form was observed only in stromal cells from healthy children, whereas in MDS and MDS-AML basal levels were maintained suggesting constitutive p38MAPK activation. Our study suggested the possible importance in pediatric MDS of p38MAPK signaling pathway which may be a future therapeutic target. (C) 2009 Elsevier Ltd. All rights reserved.

Genetic heterogeneity in familial acute myelogenous leukemia: Evidence for a second locus at chromosome 16q21-23.2

The identification of genes responsible for the rare cases of familial leukemia may afford insight into the mechanism underlying the more common sporadic occurrences. Here we test a single family with 11 relevant meioses transmitting autosomal dominant acute myelogenous leukemia (AML) and myelodysplasia for linkage to three potential candidate loci. In a different family with inherited AML, linkage to chromosome 21q22.1-22.2 was recently reported; we exclude linkage to 21q22.1-22.2, demonstrating that familial AML is a heterogeneous disease. After reviewing familial leukemia and observing anticipation in the form of a declining age of onset with each generation, we had proposed 9p21-22 and 16q22 as additional candidate loci. Whereas linkage to 9p21-22 can be excluded, the finding of a maximum two-point LOD score of 2.82 with the microsatellite marker D16S522 at a recombination fraction theta = 0 provides evidence supporting linkage to 16q22. Haplotype analysis reveals a 23.5-cM (17.9-Mb) commonly inherited region among all affected family members extending from D16S451 to D1GS289, In order to extract maximum linkage information with missing individuals, incomplete informativeness with individual markers in this interval, and possible deviance from strict autosomal dominant inheritance, we performed nonparametric linkage analysis (NPL) and found a maximum NPL statistic corresponding to a P-value of .00098, close to the maximum conditional probability of linkage expected for a pedigree with this structure. Mutational analysis in this region specifically excludes expansion of the AT-rich minisatellite repeat FRA16B fragile site and the CAG trinucleotide repeat in the E2F-4 transcription factor. The ''repeat expansion detection'' method, capable of detecting dynamic mutation associated with anticipation, more generally excludes large CAG repeat expansion as a cause of leukemia in this family.