Transcription factor GATA-2 gene is located near 3q21 breakpoints in myeloid leukemia

A patient with a germline GATA2 mutation and primary myelofibrosis

First description of a patient with a germline GATA2 mutation and diagnosis of primary myelofibrosis. Development of bone marrow failure on a Janus kinase inhibitor.

Gynecologic manifestations in Emberger syndrome

Immune system vulnerability seems to play a significant role in the development and malignant transformation of pre-malignant squamous cell lesions. Emberger syndrome is a condition that affects the immune system, which is caused by GATA2 gene mutations. Our objective was to present the gynecologic expressions of this rare syndrome in our case. Here, we discussed a relatively young patient with findings related to Emberger syndrome such as recurrent infections, myelodysplastic syndrome, lower extremity edema, and multifocal, multicentric premalignant/malignant genital lesions. Sequencing of the GATA2 gene was accomplished for suspected Emberger syndrome and a point mutation in intron5, c1143+8C >T was detected. Gynecologists may play an important role in the early detection of Emberger syndrome and guiding multidisciplinary treatment options as the initial signs related to this rare entity can appear on the genitalia.

GATA2 deficiency and related myeloid neoplasms

The GATA2 gene codes for a hematopoietic transcription factor that through its two zinc fingers (ZF) can occupy GATA-DNA motifs in a countless number of genes. It is crucial for the proliferation and maintenance of hematopoietic stem cells. During the past 5 years, germline heterozygous mutations in GATA2 were reported in several hundred patients with various phenotypes ranging from mild cytopenia to severe immunodeficiency involving B cells, natural killer cells, CD4+ cells, monocytes and dendritic cells (MonoMAC/DCML), and myeloid neoplasia. Some patients additionally show syndromic features such as congenital deafness and lymphedema (originally defining the Emberger syndrome) or pulmonary disease and vascular problems. The common clinical denominator in all reported cohorts is the propensity for myeloid neoplasia (myelodysplastic syndrome [MDS], myeloproliferative neoplasms [MPN], chronic myelomonocytic leukemia [CMML], acute myeloid leukemia [AML]) with an overall prevalence of approximately 75% and a median age of onset of roughly 20 years. Three major mutational types are encountered in GATA2-deficient patients: truncating mutations prior to ZF2, missense mutations within ZF2, and noncoding variants in the +9.5kb regulatory region of GATA2. Recurrent somatic lesions comprise monosomy 7 and trisomy 8 karyotypes and mutations in SETBP1 and ASXL1 genes. The high risk for progression to advanced myeloid neoplasia and life-threatening infectious complications guide decision-making towards timely stem cell transplantation.

Haematopoietic and immune defects associated with GATA2 mutation

Heterozygous familial or sporadic GATA2 mutations cause a multifaceted disorder, encompassing susceptibility to infection, pulmonary dysfunction, autoimmunity, lymphoedema and malignancy. Although often healthy in childhood, carriers of defective GATA2 alleles develop progressive loss of mononuclear cells (dendritic cells, monocytes, B and Natural Killer lymphocytes), elevated FLT3 ligand, and a 90% risk of clinical complications, including progression to myelodysplastic syndrome (MDS) by 60 years of age. Premature death may occur from childhood due to infection, pulmonary dysfunction, solid malignancy and MDS/acute myeloid leukaemia. GATA2 mutations include frameshifts, amino acid substitutions, insertions and deletions scattered throughout the gene but concentrated in the region encoding the two zinc finger domains. Mutations appear to cause haplo-insufficiency, which is known to impair haematopoietic stem cell survival in animal models. Management includes genetic counselling, prevention of infection, cancer surveillance, haematopoietic monitoring and, ultimately, stem cell transplantation upon the development of MDS or another life-threatening complication.

Heritable GATA2 mutations associated with familial myelodysplastic syndrome and acute myeloid leukemia

We report the discovery of the GATA2 gene as a new myelodysplastic syndrome (MDS)/acute myeloid leukemia (AML) predisposition gene. We found the same, novel heterozygous c.1061C>T (p.Thr354Met) missense mutation in the GATA2 transcription factor gene segregating with the multigenerational transmission of MDS/AML in three families, and a GATA2 c.1063_1065delACA (p.Thr355del) mutation at an adjacent codon in a fourth MDS/AML family. The mutations reside within the second zinc finger of GATA2 which mediates DNA-binding and protein-protein interactions. We show differential effects of the mutants on transactivation of target genes, cellular differentiation, apoptosis and global gene expression. Identification of such predisposing genes to familial forms of MDS and AML is critical for more effective diagnosis and prognosis, counselling, selection of related bone marrow transplant donors, and development of therapies.

GATA-2 L359 V mutation is exclusively associated with CML progression but not other hematological malignancies and GATA-2 P250A is a novel single nucleotide polymorphism

Chronic myeloid leukemia (CML) progression is characterized by occurrence of new cytogenetic and molecular abnormalities. In the previous study, we have shown the important role of GATA-2 L359 V mutation in CML progression. To further ascertain the truth of transcription factor GATA-2 in hematological malignancies, we expanded our study to GATA-2 full length by directly sequencing and applied MassARRAY assay into GATA-2 L359 V mutation analysis. Finally, no GATA-2 L359 V mutation was found in 270 acute myeloid leukemia, 30 myelodysplastic syndrome, 50 acute lymphoblastic leukemia, 12 chronic lymphocytic leukemia, 40 CML chronic phase and 286 BCR/ABL negative myeloproliferative disorders except CML blast crisis. A new variation of GATA-2 resulted in P250A change was identified, which was not found to have statistical difference between patients with hematological malignancies and healthy control. Hence, we concluded GATA-2 L359 V is exclusively associated with CML progression but not other hematological malignancies and P250A is a new single nucleotide polymorphism.

In vivo biological effects of ATRA in the treatment of AML

BACKGROUND

All-trans retinoic acid (ATRA) is mandatory in the treatment of acute promyelocytic leukaemia (APL). Experimental studies suggest that ATRA can induce differentiation and apoptosis in leukaemia cells also for other acute myelogenous leukaemia (AML) subtypes, but the clinical observations are conflicting.

DESIGN AND METHODS

Twenty-two AML patients with non-APL disease received oral ATRA alone (22.5 mg/m2 twice daily) for two days, the patients thereafter continued ATRA together with valproic acid and theophylline. We investigated the biological effects of the initial 2 days treatment with ATRA alone. Serum/plasma samples were collected before and after 2 days of ATRA, peripheral blood AML cells were collected from all 12 patients with circulating leukaemia cells (ClinicalTrials.gov NCT00175812; EudraCT no. 2004-001663-22).

RESULTS

AML cells collected during therapy had altered flow cytometric forward and right angle light scatters but no morphological signs of differentiation. ATRA increased the percentage of circulating AML cells in G0/G1 phase for 9 out of 12 patients (p = 0.043). Circulating leukaemia cells derived during therapy had increased intracellular levels of P21 (mean increase in mean fluorescence intensity (MFI) being 18.2%, p = 0.017), and decreased levels of Gata-2 (mean decrease in MFI 19%, p = 0.026), NF-kappaB p65 (mean decrease in MFI 15.4%, p = 0.033) and Bcl-2 (mean decrease in MFI 7.2%, p = 0.005). In addition, increased systemic levels of the endothelial marker endocan (plasma) and the angioregulatory mediator angiopoietin-2 (serum) were observed.

CONCLUSIONS

In vivo ATRA treatment in AML affects leukaemic cell morphology, regulation of cell cycle progression and apoptosis, and possibly also microvascular endothelial cell functions.

Cooperation of Gata3, c-Myc and Notch in malignant transformation of double positive thymocytes

Gata transcription factors are critical regulators of proliferation and differentiation implicated in various human cancers, but specific genes activated by Gata proteins remain to be identified. We previously reported that enforced expression of Gata3 during T cell development in CD2-Gata3 transgenic mice induced CD4(+)CD8(+) double-positive (DP) T cell lymphoma. Here, we show that the presence of the DO11.10 T-cell receptor transgene, which directs DP cells towards the CD4 lineage, resulted in enhanced lymphoma development and a dramatic increase in thymocyte cell size in CD2-Gata3 transgenic mice. CD2-Gata3 DP cells expressed high levels of the proto-oncogene c-Myc but the Notch1 signaling pathway, which is known to induce c-Myc, was not activated. Gene expression profiling showed that in CD2-Gata3 lymphoma cells transcription of c-Myc and its target genes was further increased. A substantial fraction of CD2-Gata3 lymphomas had trisomy of chromosome 15, leading to an increased c-Myc gene dose. Interestingly, most lymphomas showed high expression of the Notch targets Deltex1 and Hes1, often due to activating Notch1 PEST domain mutations. Therefore, we conclude that enforced Gata3 expression converts DP thymocytes into a pre-malignant state, characterized by high c-Myc expression, whereby subsequent induction of Notch1 signaling cooperates to establish malignant transformation. The finding that Gata3 regulates c-Myc expression levels, in a direct or indirect fashion, may explain the parallel phenotypes of mice with overexpression or deficiency of either of the two transcription factors.

GATA1-related leukaemias

GATA1 is a prototypical lineage-restricted transcription factor that is central to the correct differentiation, proliferation and apoptosis of erythroid and megakaryocytic cells. Mutations in GATA1 can generate a truncated protein, which contributes to the genesis of transient myeloproliferative disorder (TMD) and acute megakaryoblastic leukaemia (AMKL) in infants with Down syndrome. Similarly, Gata1 knockdown to 5% of its wild-type level causes high incidence of erythroid leukaemia in mice. The GATA1-related leukaemias in both human and mouse could provide important insights into the mechanism of multi-step leukaemogenesis. Efforts are afoot to produce mouse models that are reflective of TMD and AMKL.

Retroviral insertional mutagenesis identifies genes that collaborate with NUP98-HOXD13 during leukemic transformation

The t(2;11)(q31;p15) chromosomal translocation results in a fusion between the NUP98 and HOXD13 genes and has been observed in patients with myelodysplastic syndrome (MDS) or acute myelogenous leukemia. We previously showed that expression of the NUP98-HOXD13 (NHD13) fusion gene in transgenic mice results in an invariably fatal MDS; approximately one third of mice die due to complications of severe pancytopenia, and about two thirds progress to a fatal acute leukemia. In the present study, we used retroviral insertional mutagenesis to identify genes that might collaborate with NHD13 as the MDS transformed to an acute leukemia. Newborn NHD13 transgenic mice and littermate controls were infected with the MOL4070LTR retrovirus. The onset of leukemia was accelerated, suggesting a synergistic effect between the NHD13 transgene and the genes neighboring retroviral insertion events. We identified numerous common insertion sites located near protein-coding genes and confirmed dysregulation of a subset of these by expression analyses. Among these genes were Meis1, a known collaborator of HOX and NUP98-HOX fusion genes, and Mn1, a transcriptional coactivator involved in human leukemia through fusion with the TEL gene. Other putative collaborators included Gata2, Erg, and Epor. Of note, we identified a common insertion site that was >100 kb from the nearest coding gene, but within 20 kb of the miR29a/miR29b1 microRNA locus. Both of these miRNA were up-regulated, demonstrating that retroviral insertional mutagenesis can target miRNA loci as well as protein-coding loci. Our data provide new insights into NHD13-mediated leukemogenesis as well as retroviral insertional mutagenesis mechanisms.

Protein lysine acetylation in normal and leukaemic haematopoiesis: HDACs as possible therapeutic targets in adult AML

Several new therapeutic strategies are now considered for acute myelogenous leukaemia (AML), including modulation of protein lysine acetylation through inhibition of histone deacetylases (HDACs): a large group of enzymes that alters the acetylation and, thereby, the function of a wide range of nuclear and cytoplasmic proteins. Firstly, HDACs can deacetylate histones as well as transcription factors, and can modulate gene expression through both these mechanisms. Secondly, acetylation is an important post-translational modulation of several proteins involved in the regulation of cell proliferation, differentiation and apoptosis (e.g., p53, tubulin, heat-shock protein 90). The only HDAC inhibitors that have been investigated in clinical studies of AML are butyrate derivatives, valproic acid and depsipeptide. In the first studies, the drugs have usually been used as continuous therapy for several weeks or months, and in most studies the drugs were used alone or in combination with all-trans retinoic acid for treatment of patients with relapsed or primary resistant AML. Neurological toxicity and gastrointestinal side effects seem to be common for all three drugs. Complete haematological remission lasting for several months has been reported for a few patients (< 5% of included patients), whereas increased peripheral blood platelet counts seem more common and have been described both for patients with AML and myelodysplastic syndromes. Taken together, these studies suggest that HDAC inhibition can mediate antileukaemic effects in AML, but for most patients the clinical benefit seems limited and further studies of combination therapy are required.

Gene expression regulation and domain function of hematopoietic GATA factors

The hierarchical gene regulatory network in hematopoiesis is highly complex, making elucidation of the processes of specification and differentiation of hematopoietic cells a challenging task. Recent discoveries have divulged the GATA factors as central to the genetic control of hematopoiesis. In particular, hematopoietic development is subject to extensive and precise regulation of GATA-1 and GATA-2 at the molecular level. We wish to emphasize the regulatory relationships between GATA-1 and GATA-2 implicated in cell development. An advanced experimental genetic approach has provided evidence that abnormalities in this network may result in a variety of blood disorders. The most striking new finding is the novel pathogenesis arising from GATA-1 dysfunction that leads to leukemia.

Molecular heterogeneity in AML/MDS patients with 3q21q26 rearrangements

Patients with 3q21q26 rearrangements seem to share similar clinicopathologic features and a common molecular mechanism, leading to myelodysplasia or acute myeloid leukemia (AML). The ectopic expression of EVI1 (3q26) has been implicated in the dysplasia that characterizes this subset of myeloid neoplasias. However, lack of EVI1 expression has been reported in several cases, and overexpression of EVI1 was detected in 9% of AML cases without 3q26 abnormalities. We report the molecular characterization of seven patients with inv(3)(q21q26), t(3;3)(q21;q26) or related abnormalities. EVI1 expression was detected in only one case, and thus ectopic expression of this gene failed to explain all of these cases. GATA2 (3q21) was found to be overexpressed in 5 of the 7 patients. GATA2 is highly expressed in stem cells, and its expression dramatically decreases when erythroid and megakaryocytic differentiation proceeds. No mutations in GATA1 were found in any patient, excluding loss of function of GATA1 as the cause of GATA2 overexpression. We report finding molecular heterogeneity in patients with 3q21q26 rearrangements in both breakpoints and in the expression pattern of the genes near these breakpoints. Our data suggest that a unique mechanism is not likely to be involved in 3q21q26 rearrangements.

Roles of hematopoietic transcription factors GATA-1 and GATA-2 in the development of red blood cell lineage

The transcription factors GATA-1 and GATA-2 play key roles in gene regulation during erythropoiesis. Gene ablation studies in mouse revealed that GATA-2 is crucial for the maintenance and proliferation of immature hematopoietic progenitors, whereas GATA-1 is essential for the survival of erythroid progenitors as well as the terminal differentiation of erythroid cells. Both GATA-1 and GATA-2 are regulated in a cell-type-specific manner, their expression being strictly controlled during the development and differentiation of erythroid cells. Closer examination revealed a cross-regulatory mechanism by which GATA-1 can control the expression of GATA-2 and vice versa, possibly via essential GATA binding sites in their cis-acting elements. In addition, recent studies identified several human inherited hematopoietic disorders that are caused by mutations in cis-acting GATA binding motifs or mutations in GATA-1 itself.

Molecular, cytogenetic and genetic abnormalities in MDS and secondary AML

Myelodysplasia (MDS) is a clonal disease, which increases with age, suggesting that multiple steps are required for the evolution of the condition. Approximately 30% of MDS evolve into acute myelogenous leukemia (AML). In this review, we intend to delineate the genetic events, which may drive this sequence and therefore we will focus primarily on cytogenetic abnormalities where the genes have been identified and oncogenes and suppressor genes that have been implicated. In terms of the biological mechanisms, which characterise this process, it is generally thought that the MDS cell has impaired differentiation, and has increased apoptosis. As the disease progresses in addition, the cells have increased proliferation. As the disease evolves, the population of cells, which predominate remain immature, have decreased apoptosis and in many cases, upregulate anti-apoptotic genes and have deregulated proliferation as the number of blast cells increase. Etiological factors, which contribute to the development of leukemia, include therapeutic agents administered for a primary malignancy. The cytogenetic abnormalities, predisposition factors and genes involved in secondary leukemia will also be reviewed.

Rearrangements of chromosome band 3q21 in myeloid leukemia

Chromosome rearrangements affecting band 3q21, namely, the inv(3)(q21q26), the t(3;3)(q21;q26), and the t(1;3)(p36;q21), are associated with a particularly poor prognosis in myeloid leukemia or myelodysplasia. Originally, inv(3) and t(3;3) breakpoints have been reported to cluster in a region (breakpoint cluster region, BCR) of approximately 30 kb, which is located centromeric and downstream of the ribophorin I (RPN-I) gene. More recently, we established a PAC contig that includes the 3q21 BCR, and used these PAC clones to map breakpoints in patient samples by both metaphase and interphase fluorescence in situ hybridization (FISH) analysis. A significant proportion of inv(3) and t(3;3) breakpoints was located at sometimes considerable distances centromeric of the originally described BCR, in a region recently also implicated in t(1;3) rearrangements. These breakpoints may thus define a second, centromeric BCR (BCR-C), or extend the original 3q21 BCR to a size of approximately 100 kb. Activation of the EVI-1 gene in 3q26 by regulatory sequences of the housekeeping gene RPN-I has been suggested as a leukemogenic mechanism in patients with inv(3) and t(3;3). However, despite a number of characteristics that make EVI-1 an attractive candidate oncogene, its biological properties fail to fully explain the phenotype of leukemias carrying 3q rearrangements. Several additional candidate genes have been identified in or near the 3q21 breakpoint region, but their possible contribution to the characteristics of leukemias with 3q21 rearrangements remains to be explored.

Interphase fluorescence in situ hybridization assay for the detection of 3q21 rearrangements in myeloid malignancies

In myeloid malignancies, chromosome rearrangements involving band 3q21 are associated with a particularly poor prognosis of the disease. Their sensitive and unequivocal detection is therefore of great clinical importance. In this report, we describe the establishment of an interphase fluorescence in situ hybridization (FISH) assay that complements classical cytogenetic analysis in the diagnosis of such aberrations. PACs that map centromeric and telomeric of known 3q21 breakpoints were labeled with different fluorescent dyes, and the separation of the normally colocalizing signals was used as an indicator of the presence of a 3q21 rearrangement. Two cell lines and 10 primary samples from myeloid leukemia and myelodysplastic syndrome (MDS) patients with 3q21 rearrangements were investigated using the newly established method. The rate of false positivity was determined in 27 control samples from patients with various types of myeloid malignancies. In addition to providing a sensitive and rapid test for the detection of 3q21 aberrations, the interphase FISH assay yields preliminary information about the localization of individual breakpoints. Six of the 10 breakpoints in the patient samples map to an only recently described breakpoint cluster region (BCR) 60 kb centromeric of the originally reported 3q21 BCR. These findings may contribute to the understanding of the molecular basis of the clinical features associated with 3q21 rearrangements.