Acute myeloid leukemia with the t(8;21) translocation: clinical consequences and biological implications

The Role of Epithelial-to-Mesenchymal Transition Transcription Factors (EMT-TFs) in Acute Myeloid Leukemia Progression

Acute myeloid leukemia (AML) is a diverse malignancy originating from myeloid progenitor cells, with significant genetic and clinical variability. Modern classification systems like those from the World Health Organization (WHO) and European LeukemiaNet use immunophenotyping, molecular genetics, and clinical features to categorize AML subtypes. This classification highlights crucial genetic markers such as FLT3, NPM1 mutations, and MLL-AF9 fusion, which are essential for prognosis and directing targeted therapies. The MLL-AF9 fusion protein is often linked with therapy-resistant AML, highlighting the risk of relapse due to standard chemotherapeutic regimes. In this sense, factors like the ZEB, SNAI, and TWIST gene families, known for their roles in epithelial-mesenchymal transition (EMT) and cancer metastasis, also regulate hematopoiesis and may serve as effective therapeutic targets in AML. These genes contribute to cell proliferation, differentiation, and extramedullary hematopoiesis, suggesting new possibilities for treatment. Advancing our understanding of the molecular mechanisms that promote AML, especially how the bone marrow microenvironment affects invasion and drug resistance, is crucial. This comprehensive insight into the molecular and environmental interactions in AML emphasizes the need for ongoing research and more effective treatments.

Nucleic acid therapeutics as differentiation agents for myeloid leukemias

Differentiation therapy has proven to be a success story for patients with acute promyelocytic leukemia. However, the remaining subtypes of acute myeloid leukemia (AML) are treated with cytotoxic chemotherapies that have limited efficacy and a high likelihood of resistance. As differentiation arrest is a hallmark of AML, there is increased interest in developing differentiation-inducing agents to enhance disease-free survival. Here, we provide a comprehensive review of current reports and future avenues of nucleic acid therapeutics for AML, focusing on the use of targeted nucleic acid drugs to promote differentiation. Specifically, we compare and discuss the precision of small interfering RNA, small activating RNA, antisense oligonucleotides, and aptamers to modulate gene expression patterns that drive leukemic cell differentiation. We delve into preclinical and clinical studies that demonstrate the efficacy of nucleic acid-based differentiation therapies to induce leukemic cell maturation and reduce disease burden. By directly influencing the expression of key genes involved in myeloid maturation, nucleic acid therapeutics hold the potential to induce the differentiation of leukemic cells towards a more mature and less aggressive phenotype. Furthermore, we discuss the most critical challenges associated with developing nucleic acid therapeutics for myeloid malignancies. By introducing the progress in the field and identifying future opportunities, we aim to highlight the power of nucleic acid therapeutics in reshaping the landscape of myeloid leukemia treatment.

Homoharringtonine: updated insights into its efficacy in hematological malignancies, diverse cancers and other biomedical applications

HHT has emerged as a notable compound in the realm of cancer treatment, particularly for hematological malignancies. Its multifaceted pharmacological properties extend beyond traditional applications, warranting an extensive review of its mechanisms and efficacy. This review aims to synthesize comprehensive insights into the efficacy of HHT in treating hematological malignancies, diverse cancers, and other biomedical applications. It focuses on elucidating the molecular mechanisms, therapeutic potential, and broader applications of HHT. A comprehensive search for peer-reviewed papers was conducted across various academic databases, including ScienceDirect, Web of Science, Scopus, American Chemical Society, Google Scholar, PubMed/MedLine, and Wiley. The review highlights HHT's diverse mechanisms of action, ranging from its role in leukemia treatment to its emerging applications in managing other cancers and various biomedical conditions. It underscores HHT's influence on cellular processes, its efficacy in clinical settings, and its potential to alter pathological pathways. HHT demonstrates significant promise in treating various hematological malignancies and cancers, offering a multifaceted approach to disease management. Its ability to impact various physiological pathways opens new avenues for therapeutic applications. This review provides a consolidated foundation for future research and clinical applications of HHT in diverse medical fields.

The core concepts of core binding factor acute myeloid leukemia: Current considerations for prognosis and treatment

Core binding factor acute myeloid leukemia (CBF AML), defined by t(8;21) or inv(16), is a subset of favorable risk AML. Despite its association with a high complete remission rate after induction and relatively good prognosis overall compared with other subtypes of AML, relapse risk after induction chemotherapy remains high. Optimizing treatment planning to promote recurrence free survival and increase the likelihood of survival after relapse is imperative to improving outcomes. Recent areas of research have included evaluation of the role of gemtuzumab in induction and consolidation, the relative benefit of increased cycles of high dose cytarabine in consolidation, the utility of hypomethylating agents and kinase inhibitors, and the most appropriate timing of stem cell transplant. Surveillance with measurable residual disease testing is increasingly being utilized for monitoring disease in remission, and ongoing investigation seeks to determine how to use this tool for early identification of patients who would benefit from proceeding to transplant. In this review, we outline the current therapeutic approach from diagnosis to relapse while highlighting the active areas of investigation in each stage of treatment.

Cytogenetic culture failure and its causes in hematological disorders; a single centre perspective

OBJECTIVE

To highlight the reasons of culture failure in bone marrow aspirate samples sent for Cytogenetic analysis and to identify the associated parameters causing this impact.

METHODOLOGY

This is a retrospective cross-sectional study conducted in the Clinical and Molecular Cytogenetics Laboratory of NIBD Hospital, Karachi, Pakistan. The rates of culture failure are assessed from the year 2017-2020 along with their reasons. Bone Marrow aspirate samples of patients with hematological malignancies were cultured for chromosomal analysis, both at the time of diagnosis or relapse. Statistical analysis was performed using SPSS version 25.

RESULTS

A total of 1061 bone marrow aspirate samples were assessed for cytogenetic culture failures from the duration of 2017 to 2020. Ratio of males was predominantly higher i.e. 62.7% than female 37.3% with Mean ± SD age was 36.78 ± 18.94. Frequency of culture failure in the year 2020 was relatively high 20% as compared to the preceding years i.e. 8% in 2017, 6% in 2018, 7% in 2019. However, the patients were diagnosed with the following hematological malignancies; ALL 23%, CML 17.1%, AML 16.5% and AA 12.5%. Among the reasons of culture failure, cytogenetic analysis of patients with on-going chemo resulted in significant culture failures with p-value < 0.001 and the hematological malignancy, Acute Promyelocytic Leukemia, significantly impacted the growth of bone marrow aspirate cultures, with p-value < 0.001.

CONCLUSION

Significant findings were associated with causative factors of culture failure including on-going treatment and sample issues of clotted bone marrow as well as with the clinical diagnosis. These evaluations facilitated in overcoming the rise in culture failures. As per our knowledge, no such data, discussing the effects of various parameters such as sample quality, diagnosis, effects of treatment etc., has been documented previously.

Acute Myeloid Leukaemia With Translocation (8;21) Masquerading as Peripheral Blood Eosinophilia Having Dysplastic Features: A Diagnostic Challenge

Eosinophilia with a modest number of blasts (<20%) in the peripheral blood and bone marrow smears raises suspicion for myeloproliferative neoplasms (MPNs) and acute myeloid leukaemia (AML). Here, we present a case of AML in a 16-year-old boy who presented with high-grade fever, respiratory distress, and generalised weakness. Marked eosinophilia with dysplastic features and occasional blasts were found in the peripheral blood. In view of dysplastic eosinophils and occasional blasts in peripheral blood, a bone marrow examination was requested which revealed increased eosinophils and their progenitors with dysplasia and a modest number of blast cells (<20%). The bone marrow findings suggest MPNs, which were eventually identified as AML having translocation (8;21) with the aid of immunophenotyping and cytogenetic studies. Eosinophilia and its phenotypic anomalies are rarely found in peripheral blood smears of AML patients with translocation (8;21) which may have been related to the leukaemic process.

Targeting UHRF1-SAP30-MXD4 axis for leukemia initiating cell eradication in myeloid leukemia

Aberrant self-renewal of leukemia initiation cells (LICs) drives aggressive acute myeloid leukemia (AML). Here, we report that UHRF1, an epigenetic regulator that recruits DNMT1 to methylate DNA, is highly expressed in AML and predicts poor prognosis. UHRF1 is required for myeloid leukemogenesis by maintaining self-renewal of LICs. Mechanistically, UHRF1 directly interacts with Sin3A-associated protein 30 (SAP30) through two critical amino acids, G572 and F573 in its SRA domain, to repress gene expression. Depletion of UHRF1 or SAP30 derepresses an important target gene, MXD4, which encodes a MYC antagonist, and leads to suppression of leukemogenesis. Further knockdown of MXD4 can rescue the leukemogenesis by activating the MYC pathway. Lastly, we identified a UHRF1 inhibitor, UF146, and demonstrated its significant therapeutic efficacy in the myeloid leukemia PDX model. Taken together, our study reveals the mechanisms for altered epigenetic programs in AML and provides a promising targeted therapeutic strategy against AML.

RUNX1T1 function in cell fate

RUNX1T1 (Runt-related transcription factor 1, translocated to 1), a myeloid translocation gene (MTG) family member, is usually investigated as part of the fusion protein RUNX1-RUNX1T1 for its role in acute myeloid leukemia. In the main, by recruiting histone deacetylases, RUNX1T1 negatively influences transcription, enabling it to regulate the proliferation and differentiation of hematopoietic progenitors. Moreover, the formation of blood vessels, neuronal differentiation, microglial activation following injury, and intestinal development all relate closely to the expression of RUNX1T1. Furthermore, through alternative splicing of RUNX1T1, short and long isoforms have been noted to mediate adipogenesis by balancing the differentiation and proliferation of adipocytes. In addition, RUNX1T1 plays wide-ranging and diverse roles in carcinoma as a biomarker, suppressor, or positive regulator of carcinogenesis, closely correlated to specific organs and dominant signaling pathways. The aim of this work was to investigate the structure of RUNX1T1, which contains four conserved nervy homolog domains, and to demonstrate crosstalk with the Notch signaling pathway. Moreover, we endeavored to illustrate the effects of RUNX1T1 on cell fate from multiple aspects, including its influence on hematopoiesis, neuronal differentiation, microglial activation, intestinal development, adipogenesis, angiogenesis, and carcinogenesis.

Chromosome Territories in Hematological Malignancies

Chromosomes are organized in distinct nuclear areas designated as chromosome territories (CT). The structural formation of CT is a consequence of chromatin packaging and organization that ultimately affects cell function. Chromosome positioning can identify structural signatures of genomic organization, especially for diseases where changes in gene expression contribute to a given phenotype. The study of CT in hematological diseases revealed chromosome position as an important factor for specific chromosome translocations. In this review, we highlight the history of CT theory, current knowledge on possible clinical applications of CT analysis, and the impact of CT in the development of hematological neoplasia such as multiple myeloma, leukemia, and lymphomas. Accumulating data on nuclear architecture in cancer allow one to propose the three-dimensional nuclear genomic landscape as a novel cancer biomarker for the future.

Mosaic loss of chromosome Y promotes leukemogenesis and clonal hematopoiesis

Mosaic loss of chromosome Y (mLOY) in blood cells is one of the most frequent chromosome alterations in adult males. It is strongly associated with clonal hematopoiesis, hematopoietic malignancies, and other hematopoietic and nonhematopoietic diseases. However, whether there is a causal relationship between mLOY and human diseases is unknown. Here, we generated mLOY in murine hematopoietic stem and progenitor cells (HSPCs) with CRISPR/Cas9 genome editing. We found that mLOY led to dramatically increased DNA damage in HSPCs. Interestingly, HSPCs with mLOY displayed significantly enhanced reconstitution capacity and gave rise to clonal hematopoiesis in vivo. mLOY, which is associated with AML1-ETO translocation and p53 defects in patients with acute myeloid leukemia (AML), promoted AML in mice. Mechanistically, loss of KDM5D, a chromosome Y-specific histone 3 lysine 4 demethylase in both humans and mice, partially recapitulated mLOY in DNA damage and leukemogenesis. Thus, our study validates mLOY as a functional driver for clonal hematopoiesis and leukemogenesis.

Repurposing cabozantinib with therapeutic potential in KIT-driven t(8;21) acute myeloid leukaemias

Cabozantinib is an orally available, multi-target tyrosine kinase inhibitor approved for the treatment of several solid tumours and known to inhibit KIT tyrosine kinase. In acute myeloid leukaemia (AML), aberrant KIT tyrosine kinase often coexists with t(8;21) to drive leukaemogenesis. Here we evaluated the potential therapeutic effect of cabozantinib on a selected AML subtype characterised by t(8;21) coupled with KIT mutation. Cabozantinib exerted substantial cytotoxicity in Kasumi-1 cells with an IC₅₀ of 88.06 ± 4.32 nM, which was well within clinically achievable plasma levels. The suppression of KIT phosphorylation and its downstream signals, including AKT/mTOR, STAT3, and ERK1/2, was elicited by cabozantinib treatment and associated with subsequent alterations of cell cycle- and apoptosis-related molecules. Cabozantinib also disrupted the synthesis of an AML1-ETO fusion protein in a dose- and time-dependent manner. In a mouse xenograft model, cabozantinib suppressed tumourigenesis at 10 mg/kg and significantly prolonged survival of the mice. Further RNA-sequencing analysis revealed that mTOR-mediated signalling pathways were substantially inactivated by cabozantinib treatment, causing the downregulation of ribosome biogenesis and glycolysis, along with myeloid leukocyte activation. We suggest that cabozantinib may be effective in the treatment of AML with t(8;21) and KIT mutation. Relevant clinical trials are warranted.

Identification of a Cryptic t(8;20;21)(q22;p13;q22) Resulting in RUNX1T1/RUNX1 Fusion in a Patient with Newly Diagnosed Acute Myeloid Leukemia

The detection of recurrent genetic abnormalities in acute myeloid leukemia (AML), including RUNX1T1/RUNX1 gene fusion, is critical for optimal medical management. Herein, we report a 45 year old woman with newly diagnosed AML and conventional chromosome studies that revealed an apparently balanced t(8;20)(q22;p13) in all 20 metaphases analyzed. A RUNX1T1/RUNX1 dual-color dual-fusion fluorescence in situ hybridization (FISH) probe set was subsequently performed and revealed a RUNX1T1/RUNX1 gene fusion. Metaphase FISH studies performed on abnormal metaphases revealed a cryptic, complex translocation resulting in RUNX1T1/RUNX1 fusion, t(8;20;21)(q22;p13;q22). This case study shows the importance of performing FISH studies or other high-resolution genetic testing concurrently with conventional chromosome studies for the detection of cryptic recurrent gene fusions in AML, particularly a focused genetic evaluation such as RUNX1T1/RUNX1 gene fusion, when specific abnormalities involving 8q22 are identified.

A Role for the Bone Marrow Microenvironment in Drug Resistance of Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a heterogeneous disease with a poor prognosis and remarkable resistance to chemotherapeutic agents. Understanding resistance mechanisms against currently available drugs helps to recognize the therapeutic obstacles. Various mechanisms of resistance to chemotherapy or targeted inhibitors have been described for AML cells, including a role for the bone marrow niche in both the initiation and persistence of the disease, and in drug resistance of the leukemic stem cell (LSC) population. The BM niche supports LSC survival through direct and indirect interactions among the stromal cells, hematopoietic stem/progenitor cells, and leukemic cells. Additionally, the BM niche mediates changes in metabolic and signal pathway activation due to the acquisition of new mutations or selection and expansion of a minor clone. This review briefly discusses the role of the BM microenvironment and metabolic pathways in resistance to therapy, as discovered through AML clinical studies or cell line and animal models.

Roles of Histone Deacetylases in Acute Myeloid Leukemia With Fusion Proteins

Accurate orchestration of gene expression is critical for the process of normal hematopoiesis, and dysregulation is closely associated with leukemogenesis. Epigenetic aberration is one of the major causes contributing to acute myeloid leukemia (AML), where chromosomal rearrangements are frequently found. Increasing evidences have shown the pivotal roles of histone deacetylases (HDACs) in chromatin remodeling, which are involved in stemness maintenance, cell fate determination, proliferation and differentiation, via mastering the transcriptional switch of key genes. In abnormal, these functions can be bloomed to elicit carcinogenesis. Presently, HDAC family members are appealing targets for drug exploration, many of which have been deployed to the AML treatment. As the majority of AML events are associated with chromosomal translocation resulting in oncogenic fusion proteins, it is valuable to comprehensively understand the mutual interactions between HDACs and oncogenic proteins. Therefore, we reviewed the process of leukemogenesis and roles of HDAC members acting in this progress, providing an insight for the target anchoring, investigation of hyperacetylated-agents, and how the current knowledge could be applied in AML treatment.

Zeb1 modulates hematopoietic stem cell fates required for suppressing acute myeloid leukemia

Zeb1, a zinc finger E-box binding homeobox epithelial-mesenchymal transition (EMT) transcription factor, confers properties of "stemness," such as self-renewal, in cancer. Yet little is known about the function of Zeb1 in adult stem cells. Here, we used the hematopoietic system as a well-established paradigm of stem cell biology to evaluate Zeb1-mediated regulation of adult stem cells. We employed a conditional genetic approach using the Mx1-Cre system to specifically knock out (KO) Zeb1 in adult hematopoietic stem cells (HSCs) and their downstream progeny. Acute genetic deletion of Zeb1 led to rapid-onset thymic atrophy and apoptosis-driven loss of thymocytes and T cells. A profound cell-autonomous self-renewal defect and multilineage differentiation block were observed in Zeb1-KO HSCs. Loss of Zeb1 in HSCs activated transcriptional programs of deregulated HSC maintenance and multilineage differentiation genes and of cell polarity consisting of cytoskeleton-, lipid metabolism/lipid membrane-, and cell adhesion-related genes. Notably, epithelial cell adhesion molecule (EpCAM) expression was prodigiously upregulated in Zeb1-KO HSCs, which correlated with enhanced cell survival, diminished mitochondrial metabolism, ribosome biogenesis, and differentiation capacity and an activated transcriptomic signature associated with acute myeloid leukemia (AML) signaling. ZEB1 expression was downregulated in AML patients, and Zeb1 KO in the malignant counterparts of HSCs - leukemic stem cells (LSCs) - accelerated MLL-AF9- and Meis1a/Hoxa9-driven AML progression, implicating Zeb1 as a tumor suppressor in AML LSCs. Thus, Zeb1 acts as a transcriptional regulator in hematopoiesis, critically coordinating HSC self-renewal, apoptotic, and multilineage differentiation fates required to suppress leukemic potential in AML.

Kidney Failure and Abdominal Discomfort as Initial Signs of Extramedullary Acute Myelogenous Leukemia

Although rare, acute myelogenous leukemia (AML) can include extramedullary manifestations, sometimes presenting as a solid tumor called a myeloid sarcoma. Myeloid sarcoma can be the cause of the initial presenting complaint before AML diagnosis, or may be detected as a sign of disease-relapse after treatment. Here, we report a case in which the initial presentation included abdominal discomfort and signs of kidney failure. Further investigation revealed signs of unilateral hydronephrosis. Due to a diagnostic delay, the patient was diagnosed with AML with extramedullary manifestation only after the development of full-blown leukemia. Biopsy of the compressive tumor confirmed an extramedullary myeloid sarcoma, and [¹⁸F]-FDG-PET/CT proved useful for patient diagnosis and follow-up. This case report illustrates the importance of thorough examination and diagnosis, as a serious underlying disease with a rare cause can debut with an unusual presentation.

Time point-dependent concordance and prognostic significance of flow cytometry and real time quantitative PCR for measurable/minimal residual disease detection in acute myeloid leukemia with t(8;21)(q22;q22.1)

BACKGROUND

Flow cytometry (FCM) and PCR are reliable methods for assessing minimal residual disease (MRD) in acute myeloid leukemia with t(8;21)(q22;q22.1). The aim of this study was to analyze the concordant rate of these two methods and their prognostic significance.

METHODS

PCR and FCM were simultaneously used for MRD analysis at four different time points on 450 BM samples from 124 patients with AML with t(8;21)(q22;q22.1). The four monitoring time points included post-induction (first), after the first consolidation (second) and the second consolidation (third), and at the end of chemotherapy or before Allo/Auto stem cell transplantation (fourth).

RESULTS

The concordant rates of the two methods were 33.06%, 25.81%, 49.59%, and 75.31%, respectively, and the main discordant cases were FCM-/PCR+ cases. At all monitoring time points, the MRD level ≥ 10^-4 by FCM indicated a poor 3-year Relapse-Free Survival (RFS) (p < 0.001). More than 2-log MRD reduction by PCR after induction and more than 3-log reduction by PCR after the first consolidation remained the significant predictors of better RFS (p < 0.001). After the second consolidation, the negative MRD by PCR (<10-5) was also associated with improved RFS (p = 0.002). A > 1-log increase in PCR can effectively predict recurrence after molecular remission (p < 0.001). In the multivariate analysis, MRD≥0.01% by. FCM and less than 2-log MRD reduction by PCR after induction remained the significant predictors of poor RFS (p < 0.05).

CONCLUSIONS

FCM+ always indicates a poor prognosis. Sequential monitoring by PCR is of significance for evaluating prognosis. Our findings suggest a complementary role of two analyses in optimizing risk stratification in clinical practice.

RUNX1 gene expression in Egyptian acute myeloid leukemia patients: may it have therapeutic implications?

Background

Acute myeloid leukemia represents the highest percentage of all adult acute leukemia variants. Runt-related transcription factor1 (RUNX1), a transcription factor with a known tumor suppressor function, was recently reported as a tumor promoter in acute myeloid leukemia (AML). We investigated the role of RUNX1 gene expression level in Egyptian AML patients and delineated its clinical significance.

Results

We measured RUNX1 gene expression level using reverse transcription-quantitative polymerase chain reaction and found that the RUNX1 gene expression level was significantly higher than the control group (p < 0.001). Patients with FMS-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) mutations had a higher expression level of RUNX1 (p = 0.023). The male patients expressed a significantly higher level of RUNX1 (p = 0.046).

Conclusions

The RUNX1 gene is highly expressed in Egyptian AML patients. It has a relation to FLT3-ITD, which may give a clue that patients carrying this mutation may benefit from new treatments that target RUNX1 in the future. Further studies on a larger number of patients with different ethnic groups may give a clearer vision of the therapeutic implications of a new molecular target.

Allogeneic hematopoietic stem cell transplant in pediatric acute myeloid leukemia: Lessons learnt from a tertiary care center in India

There is paucity of data on outcomes of MSD-HSCT in children with relapsed or high-risk AML from developing countries, which have unique challenges including adverse host factors and resource constraints. We retrospectively reviewed records of children (age ≤ 18 years) who underwent MSD-HSCT for AML at our center from 2009 to 2019 to evaluate clinical outcome and its predictors using Cox proportional hazards model. There were 46 children (36 boys and 10 girls) with mean age 10.7 ± 4.8 years. Indication for HSCT was relapsed AML in CR2 (n = 37), primary refractory (n = 3), or relapsed refractory disease (n = 3); high-risk (n = 1) or secondary (n = 2) AML in CR1. Five-year EFS and OS were 33.3 ± 7.2% and 36.3 ± 7.6%, respectively. On multivariate analysis, CR1 duration less than 12 months, presence of active disease at transplant, and use of bone marrow stem cell graft were associated with poorer EFS and OS. There was one (2.2%) TRM, while disease relapse occurred in 20/40 patients who underwent HSCT in remission. Though the 5-year EFS and OS were inferior to results reported from high-income countries, relapse (and not TRM) was the major cause of treatment failure. A well-sustained CR1, achievement of disease remission, and use of peripheral blood allograft seem imperative to a successful transplant. Targeted therapy along with HSCT may be the option for those with early relapse.

An Unusual Case of Acute Myeloid Leukemia with t(8:21) Presenting with Hypereosinophilia Showing Dysplastic Features

Acute myeloid leukemia (AML) with specific genetic abnormalities is a clinically, biologically, and prognostically distinct category with some of the entities in it displaying characteristic morphology. AML with t(8:21) is one such subtype carrying favorable prognosis with specific blast morphology. Eosinophilia, characteristically, has been described till date in AML with inv (16); however, hypereosinophilia with prominent dysplastic features has yet not been seen with any AML subtype. We report the case of an 8-year-old child presenting with massive splenomegaly, hypereosinophilia, and low marrow blast percentage. The initial clinical and hematological impression was that of a chronic myeloproliferative neoplasm, which was later diagnosed as AML with t(8:21) with the help of cytogenetic studies. The case report highlights the unusual and extremely rare presentation of this AML subtype and the importance of cytogenetic studies in definite categorization, especially in cases with overlapping morphological and immunophenotypic findings.

[The prognostic value of cloned genetic mutations detected by second-generation sequencing in RUNX1-RUNX1T1 positive acute myeloid leukemia patients receiving intensive consolidation therapy]

Objective: To investigate the prognostic value of clonal gene mutations detected by second-generation sequencing in patients with positive RUNX1-RUNX1T1 acute myeloid leukemia (AML) who received high-dose chemotherapy or autologous transplantation (intensive consolidation therapy) in the first complete remission (CR(1)) state. Methods: 79 AML patients with positive RUNX1-RUNX1T1 who received intensive consolidation therapy in CR(1) state from July 2011 to August 2017 were analyzed retrospectively. Kaplan-Meier curve and Cox regression model were used to figure out the effect of leukocyte counts at onset and gene mutations for prognosis. Results: C-KIT, FLT3, CEBPA and DNMT3A gene mutations were found in 25 (31.6%) , 6 (7.6%) , 7 (8.9%) and 1 (1.3%) patient among the population. Mutations in C-KIT exon17 and C-KIT exon8 were detected in 19 (24.1%) and 5 (6.3%) cases, respectively, and mutations of FLT3-ITD were confirmed in 5 (6.3%) cases. The higher leukocyte counts presented at onset of leukemia, the shorter overall survival (OS) was seen in these patients (P=0.03) . Patients with C-KIT exon17 mutation had significantly shorter OS (P=0.01) and disease free survival (DFS) (P=0.006) compared with those without gene mutations, and patients with FLT3-ITD gene mutation got the inferior OS (P=0.048) and DFS (P=0.071) . Conclusion: In AML patients with positive RUNX1-RUNX1T1 receiving intensive consolidation therapy, the white blood cell counts at onset of leukemia, C-KIT mutations in exon 17, and FLT3-ITD gene mutations suggest poor prognosis, which would contribute to elaborate risk stratification, personalized treatment and predict prognosis for these patients.

Single‑cell RNA sequencing of t(8;21) acute myeloid leukemia for risk prediction

Single-cell RNA sequencing (scRNA-seq) of bone marrow or peripheral blood samples from patients with acute myeloid leukemia (AML) enables the characterization of heterogeneous malignant cells. A total of 87 cells from two patients with t(8;21) AML were analyzed using scRNA-seq. Clustering methods were used to separate leukemia cells into different sub-populations, and the expression patterns of specific marker genes were used to annotate these populations. Among the 31 differentially expressed genes in the cells of a patient who relapsed after hematopoietic stem cell transplantation, 13 genes were identified to be associated with leukemia. Furthermore, three genes, namely AT-rich interaction domain 2, lysine methyltransferase 2A and synaptotagmin binding cytoplasmic RNA interacting protein were validated as possible prognostic biomarkers using two bulk expression datasets. Taking advantage of scRNA-seq, the results of the present study may provide clinicians with several possible biomarkers to predict the prognostic outcomes of t(8;21) AML.

Trisomy 8 in acute myeloid leukemia

Introduction: Trisomy 8 is one of the most common cytogenetic alterations in acute myeloid leukemia (AML), with a frequency between 10% and 15%.Areas covered: The authors summarize the latest research regarding biological, translational and clinical aspects of trisomy 8 in AML.Expert opinion: Trisomy 8 can be found together with other karyotypes, although it also occurs as a sole aberration. The last decade's research has brought attention to molecular genetic alterations as strong contributors of leukemogenesis. AML with trisomy 8 seems to be associated with mutations in DNA methylation genes, spliceosome complex genes, and myeloid transcription factor genes, and these alterations probably have stronger implication for leukemic pathogenesis, treatment and hence prognosis, than the existence of trisomy 8 itself. Especially mutations in the RUNX1 and ASXL1 genes occur in high frequencies, and search for such mutations should be mandatory part of the diagnostic workup. AML with trisomy 8 is classified as intermediate-risk AML after recent European Leukemia Net (ELN) classification, and hence allogenic hematopoietic stem cell transplantation (Allo-HSCT) should be consider as consolidation therapy for this patient group.Trisomy 8 is frequently occurring in AML, although future molecular genetic workup should be performed, to optimize the diagnosis and treatment of these patients.

Identification of chromosomal abnormalities and genomic features in near-triploidy/tetraploidy-acute leukemia by fluorescence in situ hybridization

Background

Near-triploidy/tetraploidy is rarely found in acute leukemia. Only limited data are available to characterize this condition, and it remains largely unknown.

Patients and methods

In our study, we performed karyotype analysis on 1,031 patients diagnosed with acute leukemia from 2006 to 2018. A total of 10 patients of near-triploidy/tetraploidy karyotype were enrolled. Two cases of near-triploidy (66-79 chromosomes) and eight cases of near-tetraploidy (84-100 chromosomes) were identified. Bone marrow samples of these 10 patients were analyzed by fluorescence in situ hybridization with 19 commercially available probes that detected a small portion of gene alterations and large regions of chromosome amplifications.

Results

Of the six patients with acute myelocytic leukemia, we detected three cases of double t(8;21)(q22;q22) that have not been previously reported, and one of them demonstrated ins(21;8) (q22;q24q22). We also describe a novel pediatric case carrying double t(15;17)(q22;q21) and receiving targeted treatment with all-trans retinoic acid therapy. To date, this case has responded well to the regimen and has shown continuous complete remission. All patients received chemotherapy. One of them received allogeneic hematopoietic stem cell transplant (HSCT) and survived for 22 months. Eight of the 10 patients died, and the median overall survival was 11 months.

Conclusion

Using fluorescence in situ hybridization, we identified the distinct complex karyotype of near-triploidy/tetraploidy and provided further prognostic information. Tetraploidy acute promyelocytic leukemia had favorable prognosis; thus, HSCT was not necessary. The case of insertion t(21;8)(q22;q24q22) in tetraploidy responded poorly to chemotherapy and achieved molecular remission with difficultly. Data from patients in this group indicated that near-triploidy/tetraploidy acute leukemia has poor prognosis and new therapy is urgently needed.

The immunophenotypic characteristics and flow cytometric scoring system of acute myeloid leukemia with t(8;21) (q22;q22); RUNX1-RUNX1T1

INTRODUCTION

The translocation t(8;21) is one of the most frequent chromosome translocations in AML. Molecular (cyto)genetics is regarded as the gold standard for diagnosis. However, due to the complicated variety of AML-related genetic abnormalities, comprehensive screening for all of these abnormalities may not be cost-effective. Therefore, a flow cytometric (FC) scoring system was generated in this study for rapid screening and diagnosis of t(8;21)AML.

METHODS

The immunophenotypic characteristics of leukemic cells and neutrophils in cases with t(8;21) AML or other subtypes of AML were analyzed to find a method for the flow diagnosis of t(8;21) AML.

RESULTS

In this study, we picked six FC features pointing to the diagnosis of t(8;21) AML: The blasts show high-intensity expression of CD34; aberrant expression of CD19, cCD79a, and CD56 in myeloblasts; co-expression of CD56 in neutrophils, especially in immature neutrophils; and a maturity disturbance in granulocytes. A six-point score was devised using these features. By ROC analysis, the AUC was 0.952, and the sensitivity, specificity, PPV, and NPV were 0.86, 0.90. 0.91, and 0.84 when the score was ≥3 points. The score was then prospectively validated on an independent cohort, and the AUC of the ROC curve for the validation cohort was 0.975. When the cutoff value was set at 3, the obtained sensitivity and specificity values were 0.91 and 0.94, respectively.

CONCLUSIONS

The FC score described can be used for the identification and rapid screening of t(8;21) AML.

Mediation analysis reveals common mechanisms of RUNX1 point mutations and RUNX1/RUNX1T1 fusions influencing survival of patients with acute myeloid leukemia

Alterations of RUNX1 in acute myeloid leukemia (AML) are associated with either a more favorable outcome in the case of the RUNX1/RUNX1T1 fusion or unfavorable prognosis in the case of point mutations. In this project we aimed to identify genes responsible for the observed differences in outcome that are common to both RUNX1 alterations. Analyzing four AML gene expression data sets (n = 1514), a total of 80 patients with RUNX1/RUNX1T1 and 156 patients with point mutations in RUNX1 were compared. Using the statistical tool of mediation analysis we identified the genes CD109, HOPX, and KIAA0125 as candidates for mediator genes. In an analysis of an independent validation cohort, KIAA0125 again showed a significant influence with respect to the impact of the RUNX1/RUNX1T1 fusion. While there were no significant results for the other two genes in this smaller validation cohort, the observed relations linked with mediation effects (i.e., those between alterations, gene expression and survival) were almost without exception as strong as in the main analysis. Our analysis demonstrates that mediation analysis is a powerful tool in the identification of regulative networks in AML subgroups and could be further used to characterize the influence of genetic alterations.

An AML1-ETO/miR-29b-1 regulatory circuit modulates phenotypic properties of acute myeloid leukemia cells

Acute myeloid leukemia (AML) is characterized by an aggressive clinical course and frequent cytogenetic abnormalities that include specific chromosomal translocations. The 8;21 chromosomal rearrangement disrupts the key hematopoietic RUNX1 transcription factor, and contributes to leukemia through recruitment of co-repressor complexes to RUNX1 target genes, altered subnuclear localization, and deregulation of the myeloid gene regulatory program. However, a role of non-coding microRNAs (miRs) in t(8;21)-mediated leukemogenesis is minimally understood. We present evidence of an interplay between the tumor suppressor miR-29b-1 and the AML1-ETO (also designated RUNX1-RUNX1T1) oncogene that is encoded by the t(8;21). We find that AML1-ETO and corepressor NCoR co-occupy the miR-29a/b-1 locus and downregulate its expression in leukemia cells. Conversely, re-introduction of miR-29b-1 in leukemia cells expressing AML1-ETO causes significant downregulation at the protein level through direct targeting of the 3’ untranslated region of the chimeric transcript. Restoration of miR-29b-1 expression in leukemia cells results in decreased cell growth and increased apoptosis. The AML1-ETO-dependent differentiation block and transcriptional program are partially reversed by miR-29b-1. Our findings establish a novel regulatory circuit between the tumor-suppressive miR-29b-1 and the oncogenic AML1-ETO that controls the leukemic phenotype in t(8;21)-carrying acute myeloid leukemia.

Epimutational profile of hematologic malignancies as attractive target for new epigenetic therapies

In recent years, recurrent somatic mutations in epigenetic regulators have been identified in patients with hematological malignancies. Furthermore, chromosomal translocations in which the fusion protein partners are themselves epigenetic regulators or where epigenetic regulators are recruited/targeted by oncogenic fusion proteins have also been described. Evidence has accumulated showing that "epigenetic drugs" are likely to provide clinical benefits in several hematological malignancies, granting their approval for the treatment of myelodysplastic syndromes and cutaneous T-cell lymphomas. A large number of pre-clinical and clinical trials evaluating epigenetic drugs alone or in combination therapies are ongoing. The aim of this review is to provide a comprehensive summary of known epigenetic alterations and of the current use of epigenetic drugs for the treatment of hematological malignancies.

Application of GATA-3 gene marker in the detection of hematologic disorders in children

The aim of the present study was to investigate the use of GATA-3 markers in the detection of hematologic disorders in children. In total, 35 pediatric patients diagnosed with blood disease and treated in Henan Red Cross Blood Center from January 2014 to June 2015 were selected for the observation group. Another 32 healthy children were selected for the control group. The differences in the GATA-3 mRNA expression levels between the control and observation groups were detected via reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The differences in the GATA-3 protein expression levels were detected via enzyme-linked immunosorbent assay (ELISA) and western blot analysis. Compared with those in the healthy children, the mRNA expression levels of GATA-3 in patients with hematologic malignancies, acute lymphoblastic leukemia, myeloproliferative disorder, acute non-lymphocytic leukemia or thrombocytopenic purpura were significantly higher, and there were statistically significant differences between the groups (P<0.05). The results of ELISA showed that the GATA-3 protein expression levels in patients with hematologic malignancies (241.3±42.6 µg/l), acute lymphoblastic leukemia (196.3±21.6 µg/l), myeloproliferative disorder (284.2±45.1 µg/l), acute non-lymphocytic leukemia (269.3±31.4 µg/l) or thrombocytopenic purpura (272.1±39.1 µg/l) were significantly higher than those in healthy subjects (69.3±15.2 µg/l). The results of western blot analysis were consistent with those of ELISA. Based on our results, the expression levels of GATA-3 in healthy children and pediatric patients with blood diseases exhibit significant differences, and can be used as important markers for the clinical diagnosis of blood diseases in children.

Emerging Roles of MTG16 in Cell-Fate Control of Hematopoietic Stem Cells and Cancer

MTG16 (myeloid translocation gene on chromosome 16) and its related proteins, MTG8 and MTGR1, define a small family of transcriptional corepressors. These corepressors share highly conserved domain structures yet have distinct biological functions and tissue specificity. In vivo studies have shown that, of the three MTG corepressors, MTG16 is uniquely important for the regulation of hematopoietic stem/progenitor cell (HSPC) proliferation and differentiation. Apart from this physiological function, MTG16 is also involved in carcinomas and leukemias, acting as the genetic target of loss of heterozygosity (LOH) aberrations in breast cancer and recurrent translocations in leukemia. The frequent involvement of MTG16 in these disease etiologies implies an important developmental role for this transcriptional corepressor. Furthermore, mounting evidence suggests that MTG16 indirectly alters the disease course of several leukemias via its regulatory interactions with a variety of pathologic fusion proteins. For example, a recent study has shown that MTG16 can repress not only wild-type E2A-mediated transcription, but also leukemia fusion protein E2A-Pbx1-mediated transcription, suggesting that MTG16 may serve as a potential therapeutic target in acute lymphoblastic leukemia expressing the E2A-Pbx1 fusion protein. Given that leukemia stem cells share similar regulatory pathways with normal HSPCs, studies to further understand how MTG16 regulates cell proliferation and differentiation could lead to novel therapeutic approaches for leukemia treatment.

Therapeutic targeting of leukemic stem cells in acute myeloid leukemia - the biological background for possible strategies

INTRODUCTION

Acute myeloid leukemia (AML) is an aggressive malignancy, caused by the accumulation of immature leukemic blasts in blood and bone marrow. There is a relatively high risk of chemoresistant relapse even for the younger patients who can receive the most intensive antileukemic treatment. Treatment directed against the remaining leukemic and preleukemic stem cells will most likely reduce the risk of later relapse. Areas covered: Relevant publications were identified through literature searches. The authors searched for original articles and recent reviews describing (i) the characteristics of leukemic/preleukemic stem cells; (ii) the importance of the bone marrow stem cell niches in leukemogenesis; and (iii) possible therapeutic strategies to target the preleukemic/leukemic stem cells. Expert opinion: Leukemia relapse/progression seems to be derived from residual chemoresistant leukemic or preleukemic stem cells, and a more effective treatment directed against these cells will likely be important to improve survival both for patients receiving intensive treatment and leukemia-stabilizing therapy. Several possible strategies are now considered, including the targeting of the epigenetic regulation of gene expression, proapoptotic intracellular signaling, cell metabolism, telomere activity and the AML-supporting effects by neighboring stromal cells. Due to disease heterogeneity, the most effective stem cell-directed therapy will probably differ between individual patients.

Peptide microarray profiling identifies phospholipase C gamma 1 (PLC-γ1) as a potential target for t(8;21) AML

The t(8;21) (q22;q22) chromosomal translocation is one of the most frequent genetic alterations in acute myeloid leukemia (AML) which has a need for improved therapeutic strategies. We found PLC-γ1 as one of the highest phosphorylated peptides in t(8;21) AML samples compared to NBM or CN-AML in our previous peptide microarray. PLC-γ1 is known to play a role in cancer progression, however, the impact of PLC-γ1 in AML is currently unknown. Therefore, we aimed to study the functional role of PLC-γ1 by investigating the cellular growth, survival and its underlying mechanism in t(8;21) AML.

In this study, PLC-γ1 expression was significantly higher in t(8;21) AML compared to other karyotypes. The PLC-γ1 protein expression was suppressed in AML1-ETO knock down cells indicating that it might induce kasumi-1 cell death. ShRNA-mediated PLC-γ1 knockdown in kasumi-1 cells significantly blocked cell growth, induced apoptosis and cell cycle arrest which was explained by the increased activation of apoptotic related and cell cycle regulatory protein expressions. Gene expression array analysis showed the up-regulation of apoptotic and DNA damage response genes together with the downregulation of cell growth, proliferation and differentiation genes in the PLC-γ1 suppressed kasumi-1 cells, consistent with the observed phenotypic effects. Importantly, PLC-γ1 suppressed kasumi-1 cells showed higher chemosensitivity to the chemotherapeutic drug treatments and lower cell proliferation upon hypoxic stress.

Taken together, these in vitro finding strongly support an important role for PLC-γ1 in the survival of t(8;21) AML mimicking kasumi-1 cells and identify PLC-γ1 as a potential therapeutic target for t(8;21) AML treatment.

Prevalence and Clinical Significance of FLT3 and NPM1 Mutations in Acute Myeloid Leukaemia Patients of Assam, India

Acute Myeloid Leukaemia (AML) is one of the common forms of haematological malignancy in adults. We analysed the prevalence and clinical significance of FMS-like tyrosine kinase 3 (FLT3) and Nucleophosmin 1 (NPM1) mutations in AML patients of North East India. Co-prevalence and clinical significance of three recurrent chromosomal translocations namely t(15; 17), t(8; 21), t(16; 16) and expression of epidermal growth factor receptor (EGFR), flow markers were also documented and co-related with disease progress. We analysed bone marrow aspirates or peripheral blood samples from 165 newly diagnosed AML patients. All clinical samples were analysed by Real Time PCR and DNA sequencing based assays. NPM1 was the most frequently detected mutation in the study population (46/165 = 27.90%, 95% CI 20.75-35.05). FLT3 mutations were detected in 27/165 (16.40%, 95% CI 10.45-22.35) patients with internal tandem duplication (FLT3-ITD) in 24/165 (14.60%, 95% CI 8.91-20.29) and FLT3-D835 in 3/165 (1.80%, 95% CI 0-4.13) patients. NPM1 mutations were associated with a higher complete remission rate and longer overall survival (P < 0.01) compared to FLT3-ITD whereas FLT3-ITD showed adverse impact with poor survival rate (P < 0.01), leukocytosis (P < 0.01) and a packed bone marrow. EGFR expression was more in patients with NPM1 mutation compared to FLT3 mutation (P = 0.09). Patients with FLT3 and NPM1 mutations uniformly expressed CD13 and CD33 whereas CD34 was associated with poor prognosis (P ≤ 0.01) in patients with NPM1 mutation. FLT3-ITD was associated with inferior overall survival. However the clinical significance of FLT3-D835 was not clear due to small number of samples. NPM1 mutation showed better prognosis with increased response to treatment in the absence of FLT3-ITD.

Assessing the miRNA sponge potential of RUNX1T1 in t(8;21) acute myeloid leukemia

t(8;21) acute myeloid leukemia (AML) is characterized by a translocation between chromosomes 8 and 21 and formation of a distinctive RUNX1-RUNX1T1 fusion transcript. This translocation places RUNX1T1 under control of the RUNX1 promoter leading to a pronounced upregulation of RUNX1T1 transcripts in t(8;21) AML, compared to normal hematopoietic cells. We investigated the role of highly-upregulated RUNX1T1 under the hypothesis that it acts as competing endogenous RNA (ceRNA) titrating microRNAs (miRNAs) away from their target transcripts and thus contributes to AML formation. Using publicly available t(8;21) AML RNA-Seq and miRNA-Seq data available from The Cancer Genome Atlas (TCGA) project, we obtained a network consisting of 605 genes that may act as ceRNAs competing for miRNAs with the suggested RUNX1T1 miRNA sponge. Among the 605 ceRNA candidates, 121 have previously been implied in cancer development. Players in the integrin, cadherin, and Wnt signaling pathways affected by the RUNX1T1 sponge were overrepresented. Finally, among a set of 21 high interest RUNX1T1 ceRNAs we found multiple genes that have previously been linked to AML formation. In conclusion, our study offers a novel look at the role of the RUNX1-RUNX1T1 fusion transcript in t(8;21) AML beyond previously investigated genetic and epigenetic aberrations.

Patients with acute myeloid leukemia can be subclassified based on the constitutive cytokine release of the leukemic cells; the possible clinical relevance and the importance of cellular iron metabolism

OBJECTIVE

Acute myeloid leukaemia (AML) is a heterogeneous malignancy; we studied how the constitutive cytokine release by the AML cells varies among patients.

METHODS

We investigated the constitutive release of 28 mediators during in vitro culture for 79 consecutive patients.

RESULTS

Constitutive cytokine release profiles differed among patients, and hierarchical clustering identified three subsets with high, intermediate and low release, respectively. The high-release subset showed high levels of most mediators, usually monocytic differentiation as well as altered mRNA expression of proteins involved in intracellular iron homeostasis and molecular trafficking; this subset also included 4 out of 6 patients with inv(16). Spontaneous in vitro apoptosis did not differ among the subsets. For the high-release patients, cytokines were released both by CD34⁺ and CD34^- cells. The mRNA and released protein levels showed statistically significant correlations only for eleven of the cytokines. The overall survival after intensive anti-leukemic therapy was significantly higher for high-release compared with low-release patients. Pharmacological targeting of iron metabolism (iron chelation, transferrin receptor blocking) altered the cytokine release profile.

CONCLUSIONS

Subclassification of AML patients based on the constitutive cytokine release may be clinically relevant and a part of a low-risk (i.e. chemosensitive) AML cell phenotype.

Multiplexed automated digital quantification of fusion transcripts: comparative study with fluorescent in-situ hybridization (FISH) technique in acute leukemia patients

BACKGROUND

The World Health Organization (WHO) classification system defines recurrent chromosomal translocations as the sole diagnostic and prognostic criteria for acute leukemia (AL). These fusion transcripts are pivotal in the pathogenesis of AL. Clinical laboratories universally employ conventional karyotype/FISH to detect these chromosomal translocations, which is complex, labour intensive and lacks multiplexing capacity. Hence, it is imperative to explore and evaluate some newer automated, cost-efficient multiplexed technologies to accommodate the expanding genetic landscape in AL.

METHODS

"nCounter® Leukemia fusion gene expression assay" by NanoString was employed to detect various fusion transcripts in a large set samples (n = 94) utilizing RNA from formalin fixed paraffin embedded (FFPE) diagnostic bone marrow biopsy specimens. This series included AL patients with various recurrent translocations (n = 49), normal karyotype (n = 19), or complex karyotype (n = 21), as well as normal bone marrow samples (n = 5). Fusion gene expression data were compared with results obtained by conventional karyotype and FISH technology to determine sensitivity/specificity, as well as positive /negative predictive values.

RESULTS

Junction probes for PML/RARA; RUNX1-RUNX1T1; BCR/ABL1 showed 100 % sensitivity/specificity. A high degree of correlation was noted for MLL/AF4 (85 sensitivity/100 specificity) and TCF3-PBX1 (75 % sensitivity/100 % specificity) probes. CBFB-MYH11 fusion probes showed moderate sensitivity (57 %) but high specificity (100 %). ETV6/RUNX1 displayed discordance between fusion transcript assay and FISH results as well as rare non-specific binding in AL samples with normal or complex cytogenetics.

CONCLUSIONS

Our study presents preliminary data with high correlation between fusion transcript detection by a throughput automated multiplexed platform, compared to conventional karyotype/FISH technique for detection of chromosomal translocations in AL patients. Our preliminary observations, mandates further vast validation studies to explore automated molecular platforms in diagnostic pathology.

New insights into transcriptional and leukemogenic mechanisms of AML1-ETO and E2A fusion proteins

BACKGROUND

Nearly 15% of acute myeloid leukemia (AML) cases are caused by aberrant expression of AML1-ETO, a fusion protein generated by the t(8;21) chromosomal translocation. Since its discovery, AML1-ETO has served as a prototype to understand how leukemia fusion proteins deregulate transcription to promote leukemogenesis. Another leukemia fusion protein, E2A-Pbx1, generated by the t(1;19) translocation, is involved in acute lymphoblastic leukemias (ALLs). While AML1-ETO and E2A-Pbx1 are structurally unrelated fusion proteins, we have recently shown that a common axis, the ETO/E-protein interaction, is involved in the regulation of both fusion proteins, underscoring the importance of studying protein-protein interactions in elucidating the mechanisms of leukemia fusion proteins.

OBJECTIVE

In this review, we aim to summarize these new developments while also providing a historic overview of the related early studies.

METHODS

A total of 218 publications were reviewed in this article, a majority of which were published after 2004.We also downloaded 3D structures of AML1-ETO domains from Protein Data Bank and provided a systematic summary of their structures.

RESULTS

By reviewing the literature, we summarized early and recent findings on AML1-ETO, including its protein-protein interactions, transcriptional and leukemogenic mechanisms, as well as the recently reported involvement of ETO family corepressors in regulating the function of E2A-Pbx1.

CONCLUSION

While the recent development in genomic and structural studies has clearly demonstrated that the fusion proteins function by directly regulating transcription, a further understanding of the underlying mechanisms, including crosstalk with other transcription factors and cofactors, and the protein-protein interactions in the context of native proteins, may be necessary for the development of highly targeted drugs for leukemia therapy.

Acute myeloid leukaemia with t(8;21)(q22;q22.3) and loss of the X chromosome

Cytogenetic abnormalities occur in approximately 60% of newly diagnosed patients with acute myeloid leukaemia (AML) and are useful in the risk stratification of AML. Translocation between chromosomes 8 and 21-t(8;21)-(q22;q22.3), which carries a favourable prognosis, is found in approximately 5% to 10% of all patients with AML. Additional chromosomal abnormalities have been described in patients with AML with t(8;21), which may impact on the favourable prognosis. We report a patient who had AML with t(8;21)(q22;q22.3) and loss of the X chromosome.

Aberrant expression of miR-9/9* in myeloid progenitors inhibits neutrophil differentiation by post-transcriptional regulation of ERG

Aberrant post-transcriptional regulation by microRNAs (miRNAs) has been shown to be involved in the pathogenesis of acute myeloid leukemia (AML). In a previous study, we performed a large functional screen using a retroviral barcoded miRNA expression library. Here, we report that overexpression of miR-9/9* in myeloid 32D cell line (32D-miR-9/9*) had profound impact on granulocyte colony-stimulating factor-induced differentiation. Further in vitro studies showed that enforced expression of miR-9/9* blocked normal neutrophil development in 32D and in primary murine lineage-negative bone marrow cells. We examined the expression of miR-9/9* in a cohort of 647 primary human AMLs. In most cases, miR-9 and miR-9* were significantly upregulated and their expression levels varied according to AML subtype, with the highest expression in MLL-related leukemias harboring 11q23 abnormalities and the lowest expression in AML cases with t(8;21) and biallelic mutations in CEBPA. Gene expression profiling of AMLs with high expression of miR-9/9* and 32D-miR-9/9* identified ETS-related gene (Erg) as the only common potential target. Upregulation of ERG in 32D cells rescued miR-9/9*-induced block in neutrophil differentiation. Taken together, this study demonstrates that miR-9/9* are aberrantly expressed in most of AML cases and interfere with normal neutrophil differentiation by downregulation of ERG.

Does aberrant membrane transport contribute to poor outcome in adult acute myeloid leukemia?

Acute myeloid leukemia in adults is a highly heterogeneous disease. Gene expression profiling performed using unsupervised algorithms can be used to distinguish specific groups of patients within a large patient cohort. The identified gene expression signatures can offer insights into underlying physiological mechanisms of disease pathogenesis. Here, the analysis of several related gene expression clusters associated with poor outcome, worst overall survival and highest rates of resistant disease and obtained from the patients at the time of diagnosis or from previously untreated individuals is presented. Surprisingly, these gene clusters appear to be enriched for genes corresponding to proteins involved in transport across membranes (transporters, carriers and channels). Several ideas describing the possible relationship of membrane transport activity and leukemic cell biology, including the "Warburg effect," the specific role of chloride ion transport, direct "import" of metabolic energy through uptake of creatine phosphate, and modification of the bone marrow niche microenvironment are discussed.

Age and genetics: how do prognostic factors at diagnosis explain disparities in acute myeloid leukemia?

OBJECTIVES

Survival disparities in acute myeloid leukemia (AML) among blacks and Hispanics have been described but not studied extensively in adults. Although younger age and cytogenetic profiles of t(8;21) and acute promyelocytic leukemia (APL) subtypes of AML are associated with improved survival, these factors have not been investigated by race. The purpose is to evaluate whether the observed survival differences for blacks and Hispanics with AML are attributable to older age at diagnosis or lower rates of favorable cytogenetic profiles at diagnosis. The hypothesis is that survival disparities for blacks and Hispanics with AML will be explained by older age at diagnosis and lower rates of favorable cytogenetics.

METHODS

Patients with AML were identified in the Surveillance Epidemiology and End Results database (1999 to 2008). Kaplan-Meier (KM) survival curves predicted survival by race/ethnicity, stratified by age. Cox proportional hazard models estimated mortality by race with adjustment for age, sex, year of diagnosis, t(8;21), and APL subtypes.

RESULTS

A total of 25,692 patients were included. Blacks and Hispanics were diagnosed at younger ages (younger than 61 y), and had higher rates of t(8;21) and APL compared with non-Hispanic whites (NHWs). The overall KM curve shows that NHWs had a worse survival compared with other races/ethnicities. However, when KM curves were stratified by age, blacks and Hispanics had worse survival in younger age categories (younger than 61 y). In multivariable models, black race was associated with an increased risk of death compared with NHWs (HR, 1.10; 95% CI, 1.04-1.16). Adjustment for t(8;21) and APL subtypes did not attenuate the disparity.

CONCLUSIONS

Despite younger age and higher prevalence of favorable cytogenetics at diagnosis, blacks and Hispanics have an increased mortality from AML compared with other racial/ethnic groups. Future studies should investigate other factors that may influence outcomes among minority populations.

Genome-wide co-occupancy of AML1-ETO and N-CoR defines the t(8;21) AML signature in leukemic cells

Background

Many leukemias result from chromosomal rearrangements. The t(8;21) chromosomal translocation produces AML1-ETO, an oncogenic fusion protein that compromises the function of AML1, a transcription factor critical for myeloid cell differentiation. Because of the pressing need for new therapies in the treatment of acute myleoid leukemia, we investigated the genome-wide occupancy of AML1-ETO in leukemic cells to discover novel regulatory mechanisms involving AML-ETO bound genes.

Results

We report the co-localization of AML1-ETO with the N-CoR co-repressor to be primarily on genomic regions distal to transcriptional start sites (TSSs). These regions exhibit over-representation of the motif for PU.1, a key hematopoietic regulator and member of the ETS family of transcription factors. A significant discovery of our study is that genes co-occupied by AML1-ETO and N-CoR (e.g., TYROBP and LAPTM5) are associated with the leukemic phenotype, as determined by analyses of gene ontology and by the observation that these genes are predominantly up-regulated upon AML1-ETO depletion. In contrast, the AML1-ETO/p300 gene network is less responsive to AML1-ETO depletion and less associated with the differentiation block characteristic of leukemic cells. Furthermore, a substantial fraction of AML1-ETO/p300 co-localization occurs near TSSs in promoter regions associated with transcriptionally active loci.

Conclusions

Our findings establish a novel and dominant t(8;21) AML leukemia signature characterized by occupancy of AML1-ETO/N-CoR at promoter-distal genomic regions enriched in motifs for myeloid differentiation factors, thus providing mechanistic insight into the leukemic phenotype.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1445-0) contains supplementary material, which is available to authorized users.

Esculetin Downregulates the Expression of AML1-ETO and C-Kit in Kasumi-1 Cell Line by Decreasing Half-Life of mRNA

One of the most frequent genetic aberrations in acute myeloid leukemia (AML) is chromosomal translocation between AML1/RUNX1 on chromosome 21 and ETO gene on chromosome 8 resulting in the expression of chimeric oncogene AML1-ETO. Although patients with t(8;21) translocation have good prognosis, 5-year survival is observed only in 50% of the cases. AML1-ETO translocation is usually accompanied by overexpression of mutant C-Kit, a tyrosine kinase, which contributes to uncontrolled proliferation of premature blood cells leading to relapse and poor prognosis. We illustrate the potential use of esculetin on leukemic cell line, Kasumi-1, bearing t(8;21) translocation and mutated C-Kit gene. Esculetin decreases the expression of AML1-ETO at both protein and transcript level within 24 hours of treatment. Half-life of AML1-ETO mRNA was reduced from 7 hours to 1.5 hours. Similarly half-life of C-Kit mRNA was reduced to 2 hours from 5 hours in esculetin treated cells. Esculetin also perturbed the expression of ectopically expressed AML1-ETO in U937 cells. The decreased expression of AML1-ETO chimeric gene was associated with increased expression of LAT1 and RUNX3 genes, targets of AML1. We envisage that discovery of a drug candidate which could target both these mutated genes would be a considerable breakthrough for future application.

STAT3 as a possible therapeutic target in human malignancies: lessons from acute myeloid leukemia

STAT3 is important for transcriptional regulation in human acute myeloid leukemia (AML). STAT3 has thousands of potential DNA binding sites but usually shows cell type specific binding preferences to a limited number of these. Furthermore, AML is a very heterogeneous disease, and studies of the prognostic impact of STAT3 in human AML have also given conflicting results. A more detailed characterization of STAT3 functions and the expression of various isoforms in human AML will therefore be required before it is possible to design clinical studies of STAT3 inhibitors in this disease, and it will be especially important to investigate whether the functions of STAT3 differ between patients. Several other malignancies also show extensive biological heterogeneity, and the present discussion and the suggested scientific approaches may thus be relevant for other cancer patients.

A Case of AML-M2 with Sole Interstitial Deletion in 9q Without AML1-ETO/Inv 16 Rearrangement and FLT3/NPMI Mutations

Conventional/molecular cytogenetics is important in identification of genomic abnormalities, for prognostication and in risk stratification of de novo patients with acute myeloid leukemias (AML). Here we present an AML M2 case showing the sole karyotypic abnormality, the rare interstitial deletion in the long arm of chromosome 9 with the loss of segment q12-q13.