DNMT3A Mutations in Patients with Acute Myeloid Leukemia in South Brazil

Epigenetic regulation in hematopoiesis and its implications in the targeted therapy of hematologic malignancies

Hematologic malignancies are one of the most common cancers, and the incidence has been rising in recent decades. The clinical and molecular features of hematologic malignancies are highly heterogenous, and some hematologic malignancies are incurable, challenging the treatment, and prognosis of the patients. However, hematopoiesis and oncogenesis of hematologic malignancies are profoundly affected by epigenetic regulation. Studies have found that methylation-related mutations, abnormal methylation profiles of DNA, and abnormal histone deacetylase expression are recurrent in leukemia and lymphoma. Furthermore, the hypomethylating agents and histone deacetylase inhibitors are effective to treat acute myeloid leukemia and T-cell lymphomas, indicating that epigenetic regulation is indispensable to hematologic oncogenesis. Epigenetic regulation mainly includes DNA modifications, histone modifications, and noncoding RNA-mediated targeting, and regulates various DNA-based processes. This review presents the role of writers, readers, and erasers of DNA methylation and histone methylation, and acetylation in hematologic malignancies. In addition, this review provides the influence of microRNAs and long noncoding RNAs on hematologic malignancies. Furthermore, the implication of epigenetic regulation in targeted treatment is discussed. This review comprehensively presents the change and function of each epigenetic regulator in normal and oncogenic hematopoiesis and provides innovative epigenetic-targeted treatment in clinical practice.

Molecular regulators of HOXA9 in acute myeloid leukemia

Dysregulation of the oncogenic transcription factor HOXA9 is a prominent feature for most aggressive acute myeloid leukemia cases and a strong indicator of poor prognosis in patients. Leukemia subtypes with hallmark overexpression of HOXA9 include those carrying MLL gene rearrangements, NPM1c mutations, and other genetic alternations. A growing body of evidence indicates that HOXA9 dysregulation is both sufficient and necessary for leukemic transformation. The HOXA9 mRNA and protein regulation includes multilayered controls by transcription factors (such as CDX2/4 and USF2/1), epigenetic factors (such as MLL-menin-LEDGF, DOT1L, ENL, HBO1, NPM1c-XPO1, and polycomb proteins), microRNAs (such as miR-126 and miR-196b), long noncoding RNAs (such as HOTTIP), three-dimensional chromatin interactions, and post-translational protein modifications. Recently, insights into the dynamic regulation of HOXA9 have led to an advanced understanding of the HOXA9 regulome and provided new cancer therapeutic opportunities, including developing inhibitors targeting DOT1L, menin, and ENL proteins. This review summarizes recent advances in understanding the molecular mechanisms controlling HOXA9 regulation and the pharmacological approaches that target HOXA9 regulators to treat HOXA9-driven acute myeloid leukemia.

Clinical Implication of DNMT3A and TET2 Genes Mutations in Cytogenetically Normal Acute Myeloid Leukemia

BACKGROUND

Refining risk stratification of cytogenetically  normal AML (CN-AML) cases is important for decision making and tailoring of therapy. In this context genetic and epigenetic mutations was considered. Among these epigenetic regulators are DNMT3A & TET2 genes. Therefore, the aim of  this study was to determine the prevalence of DNMT3A and TET2 genes mutations and their impact on the outcome of  adult AML patients.

SUBJECTS AND METHODS

The present study is cross sectional study which was conducted on 39 adult CN-AML patients at diagnosis. For all included patients sanger sequencing was done for DNMT3A exon 23 and TET2 exon 3 genes.

RESULTS

DNMT3A mutations were detected in 8 of 39 patients (20.5%), and in 5 of 39 patients(12.8%) in TET gene. Two CN-AML  patients had combined mutations in both genes. All of the mutations detected were missense and only one was frame shift. Mutated TET2 or DNMT3A genes were significantly associated with failure of complete remission (CR) (p <0.001), higher mortality rate, shorter OS (mean=16 versus 22.7 months) and shorter DFS (mean= 9.5 versus 21.4 months) when compared to non-mutated ones.

CONCLUSION

Mutated TET2 and DNMT3A detection define a subgroup of CN-AML patients with poor outcome.

Zebrafish models of acute leukemias: Current models and future directions

Acute myeloid leukemias (AML) and acute lymphoid leukemias (ALL) are heterogenous diseases encompassing a wide array of genetic mutations with both loss and gain of function phenotypes. Ultimately, these both result in the clonal overgrowth of blast cells in the bone marrow, peripheral blood, and other tissues. As a consequence of this, normal hematopoietic stem cell function is severely hampered. Technologies allowing for the early detection of genetic alterations and understanding of these varied molecular pathologies have helped to advance our treatment regimens toward personalized targeted therapies. In spite of this, both AML and ALL continue to be a major cause of morbidity and mortality worldwide, in part because molecular therapies for the plethora of genetic abnormalities have not been developed. This underscores the current need for better model systems for therapy development. This article reviews the current zebrafish models of AML and ALL and discusses how novel gene editing tools can be implemented to generate better models of acute leukemias. This article is categorized under: Adult Stem Cells, Tissue Renewal, and Regeneration > Stem Cells and Disease Technologies > Perturbing Genes and Generating Modified Animals.

Distribution of fusion transcripts and its clinical impact in patients with acute myeloid leukemia in Sudan

OBJECTIVE

Acute myeloid leukemia (AML) is a common malignant disorder of hematopoietic progenitor cells that caused by chromosomal translocation and the formation of fusion oncogenes. This study determined the frequencies of fusion genes in Sudanese patients with AML and their clinical impacts.

METHODS

This study was conducted at Alzaeim Alazhari University, Khartoum, Sudan. A total of 97 patients with AML were recruited in the study from different clinics in Khartoum state. Quantitative real-time polymerase chain reaction was used to determine types of fusion genes.

RESULTS

The highest frequency of genetic defects was observed for AML1-ETO fusion gene (57.6%) followed by MLL-AF9 (35.1%) and FUS-ERG (7.2%). No significant differences in blast cells, hemoglobin, total white blood cells, and platelets were found between different gene fusion groups (P > 0.05). In addition, no differences in the frequency of splenomegaly, hepatomegaly and lymphadenopathy were observed between different gene fusion groups (P > 0.05). With respect to French-American-British (FAB) classification, the M2 and M3 were significantly higher in patients with AML1-ETO fusion (86%, P < 0.01) whereas M4 and M5 were higher in patients with MLL-AF9 fusion (76.5%, P < 0.01).

CONCLUSIONS

The study concluded that AML1-ETO and MLL-AF9 fusion genes were predominant in AML Sudanese patients. None of the examined clinical parameters were different between different fusion genes except for FAB stages.

Prognostic significance of DNMT3a gene expression and reactive nitrogen species in newly diagnosed Egyptian de novo adult acute myeloid leukemia patients

Background

DNA methyltransferase 3a (DNMT3a) gene is a frequently dysregulated epigenetic modifier gene involved in the process of carcinogenesis. Also, there is a dichotomous nature of nitric oxide action with the ability to both promote and repress cancers. There is a host of research work delineating the frequency of DNMT3a mutation in acute myeloid leukemia (AML), but little is known about its level of expression in AML patients or its probable relationship to nitrosative stress. This study aims at the assessment DNMT3a gene expression as well as nitric oxide levels in newly diagnosed adult patients with de novo AML. Moreover, it aims at relating these two variables to other disease features and prognostic indicators as well as treatment outcomes. The study included 45 adult de novo AML patients and 10 healthy control subjects. Measurement of DNMT3a messenger ribonucleic acid (mRNA) transcripts was done by real-time quantitative polymerase chain reaction (RQ-PCR) followed by Sanger sequencing to identify the presence or absence of DNMT3a arginine 882 (R882) mutation. This was followed by the assessment of serum nitrite level as a surrogate marker for nitric oxide radical (NO) using colorimetric methods.

Results

DNMT3a gene expression, as well as serum nitrite levels, were significantly higher among AML cases in relation to controls before chemotherapy with P values of < 0.001 and 0.035, respectively. Dividing patients into low and high expressors in relation to the hotspot mutation demonstrated no difference between the two groups in terms of demographic, clinical, and laboratory characteristics or treatment outcomes.

Conclusion

DNMT3a gene expression is increased among the AML population in relation to normal healthy controls. This may point out the need for the assessment of the influence of this gene expression on methylcytosine content of tumor samples with the subsequent implementation of hypomethylating agents as a line of therapy in cases exhibiting excessive hypermethylation.

Co-existence of mutations in myeloproliferative neoplasms and their clinical significance: a prognostic approach

OBJECTIVE

Myeloproliferative neoplasms (MPNs) are a group of clonal hematopoietic stem cell disorders that may occur after one or more mutations in hematopoietic progenitor cells. In this study, we will review the co-existence of mutations (especially dual mutations) in MPNs and its effect on the prognosis of patients.

METHODS

To find relevant published papers, we systematically searched six major international indexing databases, namely PubMed/Medline, EmBase, Cochrane central, ISI web of science, and Scopus from Feb. 2000 until Jan. 2020. We included the following keywords in the analyzes: Myeloproliferative Disorders, Mutation, Co-existence of Mutations, Acute myeloid leukemia.

RESULTS

Co-existence of several mutations in MPNs is mainly associated with a poor prognosis compared with the unimutated MPN disorders. There are several effective factors such as sequence of mutations, incidence of mutations in one cell or different cells, mutation, and MPN type.

CONCLUSION AND EXPERT COMMENTARY

It seems that monitoring the status of mutations in MPNs and recognizing the co-existence of mutations (especially dual mutations) in order to determine prognosis and possibility of progression to acute form of leukemia can lead to the prediction of prognosis in MPN patients as well as establishment of better and more reliable therapeutic strategies for patients.

FLT3-ITD Compared with DNMT3A R882 Mutation Is a More Powerful Independent Inferior Prognostic Factor in Adult Acute Myeloid Leukemia Patients After Allogeneic Hematopoietic Stem Cell Transplantation: A Retrospective Cohort Study

Objective

This study aimed to evaluate DNMT3A exon 23 mutations and their prognostic impacts in the presence of NPM1 and FLT3 mutations in acute myeloid leukemia (AML) patients who underwent allogeneic hematopoietic stem cell transplantation (HSCT).

Materials and Methods

This study comprised 128 adult AML patients referred to the Hematology-Oncology and Stem Cell Research Center of Shariati Hospital. NPM1 and FLT3-ITD mutations were detected by fragment analysis. For DNMT3A exon 23 mutation analysis, we used Sanger sequencing. Overall survival (OS) and relapse-free survival (RFS) curves were estimated by the Kaplan-Meier method and the log-rank test was used to calculate differences between groups.

Results

The prevalence of DNMT3A exon 23 mutations was 15.6% and hotspot region R882 mutations were prominent. RFS and OS were compared in patients with and without DNMT3A exon 23 mutations using univariate analysis and there was no significant difference between these groups of patients. On the contrary, the FLT3-ITD mutation significantly reduced the OS (p=0.009) and RFS (p=0.006) in AML patients after allogeneic HSCT. In the next step, patients with AML were divided into four groups regarding FLT3-ITD and DNMT3A mutations. Patients with DNMT3A R882mut/FLT3-ITDpos had the worst OS and RFS. These results indicate that DNMT3A mutations alone do not affect the clinical outcomes of AML patients undergoing allogeneic HSCT, but when accompanied by FLT3-ITD mutations, the OS was significantly reduced (5-year OS 0% for DNMT3A R882mut/FLT3-ITDpos patients vs. 62% DNMT3A R882wt/FLT3-ITDneg, p=0.025) and the relapse rate increased.

Conclusion

It can be deduced that DNMT3A R882mut/FLT3-ITDpos is an unfavorable prognostic factor in AML patients even after allogeneic HSCT.

A mutational and expressional analysis of DNMT3A in acute myeloid leukemia cytogenetic subgroups

OBJECTIVES

Despite numerous studies in order to determine the allele frequency and clinical impact of DNA methyltransferase 3 A (DNMT3A) gene mutations in acute myeloid leukemia (AML), reports about the expression analysis of this gene are rare and between the available, differences are evident.

METHODS

In this study, we decided to investigate DNMT3A possible expression changes with regard to their mutation and cytogenetic status in a series of 96 AML patients.

RESULTS

Mutations were founded in 17 of the 96 patients (17.7%) and associated with higher age and white blood cell count (P < 0.001). Our mutants have had shorter overall survival (OS) (P < 0.001) and relapse-free survival (RFS) (P = 0.011) than those without. Multivariate analysis showed that DNMT3A mutation is an independent prognostic indicator for OS and RFS (P < 0.001). In relation to expression results, we had over and under expression for our favorable and unfavorable cytogenetic subgroups, respectively (P = 0.005 and P < 0.001, respectively). In intermediate subgroup, total DNMT3A expression did not alter (P = 0.575). Interestingly, we noticed similar expression results for DNMT3A transcript 2, to that of the total.

DISCUSSION AND CONCLUSION

In relation to DNMT3A expression, from the perspective of diagnostic application and its biological significance, it is difficult to accept its primacy over cytogenetic value in favorable and unfavorable subgroups and if so, we did not address this issue in our study due to sample size limitation. In intermediate subgroup, particularly in normal karyotype-AML, given the lack of convincing results, it seems unlikely that DNMT3A expression analysis could attract attention in diagnostic workup and risk prediction of AML.

The de novo DNA methyltransferase DNMT3A in development and cancer

DNA methylation, one of the best-characterized epigenetic modifications, plays essential roles in development, aging and diseases. The de novo DNA methyltransferase DNMT3A is responsible for the establishment of de novo genomic DNA methylation patterns and, as such, involved in normal development as well as in many diseases including cancer. In recent years, our understanding of this important protein has made significant progress, which was facilitated by stunning development in the analysis of the DNA methylome of multiple organs and cell types. In this review, recent developments in the characterization of DNMT3A were discussed with special emphasis on the roles of DNMT3A in development and cancer.

Effects of somatic mutations are associated with SNP in the progression of individual acute myeloid leukemia patient: the two-hit theory explains inherited predisposition to pathogenesis

This study evaluated the effects of somatic mutations and single nucleotide polymorphisms (SNPs) on disease progression and tried to verify the two-hit theory in cancer pathogenesis. To address this issue, SNP analysis was performed using the UCSC hg19 program in 10 acute myeloid leukemia patients (samples, G1 to G10), and somatic mutations were identified in the same tumor sample using SomaticSniper and VarScan2. SNPs in KRAS were detected in 4 out of 10 different individuals, and those of DNMT3A were detected in 5 of the same patient cohort. In 2 patients, both KRAS and DNMT3A were detected simultaneously. A somatic mutation in IDH2 was detected in these 2 patients. One of the patients had an additional mutation in FLT3, while the other patient had an NPM1 mutation. The patient with an FLT3 mutation relapsed shortly after attaining remission, while the other patient with the NPM1 mutation did not suffer a relapse. Our results indicate that SNPs with additional somatic mutations affect the prognosis of AML.