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

Effect of DNMT3A R882H Hot Spot Mutations on DDX43 Promoter Methylation in Acute Myeloid Leukemia

Epigenetic alterations have been observed in many hematological malignancies, including acute myeloid leukemia (AML). Many of these alterations result from mutations in DNA methyl transferase (DNMT) enzymes, disabling them to methylate target genes in a proper way. In this case-control study, we investigated the association between R882H mutation in DNMT3A gene and DDX43 gene methylation in patients with AML. 47 AML patients and 6 controls were included in this study. After DNA extraction, amplification refractory mutation system (ARMS)-PCR was used to evaluate R882H mutations in DNMT3A gene. The high-resolution melting (HRM) method was used to determine the methylation changes of the DDX43 gene promoter. R882H mutation was only found in 10.6% (5 out of 47) of AML patients. The frequency of DDX43 gene methylation was significantly higher in patients without R882H mutations compared to patients with R882H mutations (P < 0.05). The DNMT3A R882H mutation is typically present in a minority of AML patients. Nevertheless, this mutation is associated with a reduced frequency of methylation in the DDX43 promoter region.

CD7-positive leukemic blasts with DNMT3A mutations predict poor prognosis in patients with acute myeloid leukemia

Background

DNMT3A mutations can be detected in premalignant hematopoietic stem cells and are primarily associated with clonal hematopoiesis of indeterminate potential; however, current evidence does not support assigning them to a distinct European Leukemia Net (ELN) prognostic risk stratification. CD7 is a lymphoid antigen expressed on blasts in approximately 30% of acute myeloid leukemia (AML), and its role in AML remains unclear and depends on subgroup evaluation. This study investigated the prognostic value of DNMT3A mutation combined with CD7 expression in AML.

Methods

We retrospectively analyzed the clinical data of 297 newly diagnosed non-M3 AML patients. According to the DNMT3A mutation and CD7 expression in AML cells, patients were divided into the DNMT3A-mutated/CD7-positive (CD7+), DNMT3A-mutated/CD7-negative (CD7-), DNMT3A-wild-type/CD7+, and DNMT3A-wild-type/CD7- groups.

Results

The DNMT3A-mutated/CD7+ group had lower complete remission rates and higher relapse rates. Importantly, these patients had significantly shorter overall survival (OS) and relapse-free survival (RFS). Furthermore, multivariate analysis showed that CD7+ with DNMT3A mutation was an independent risk factor for OS and RFS.

Conclusion

CD7+ with DNMT3A mutation predicts a poor prognosis in AML patients, and the immunophenotype combined with molecular genetic markers can help to further refine the current risk stratification of AML.

Chronic myelomonocytic leukemia with double-mutations in DNMT3A and FLT3-ITD treated with decitabine and sorafenib

Chronic myelomonocytic leukemia (CMML) is a heterogeneous neoplastic hematologic disorder with worse overall survival. Half of CMML have mutations, but case with concomitant mutations of DNA methyltransferase 3A (DNMT3A) and Internal tandem duplications of the juxtamembrane domain of FLT3 (FLT3-ITD) in CMML was not reported before. We reported a 51-year-old man who had CMML with concomitant mutations in DNMT3A and FLT3-ITD.The patient received decitabine and sorafenib combined treatment. In this report, we reviewed DNMT3A mutation and FLT3 mutation, and we reviewed treatment of decitabine and sorafenib. This report is significant. First: This is the first report on CMML with double-mutations of DNMT3A and FLT3-ITD. Second: It shows the importance of targeted drug in combined treatment of CMML.

DNMT3A mutations in Chinese childhood acute myeloid leukemia

BACKGROUND

DNA methyltransferase 3A (DNMT3A) mutations have been found in approximately 20% of adult acute myeloid leukemia (AML) patients and in 0% to 1.4% of children with AML, and the hotspots of mutations are mainly located in the catalytic methyltransferase domain, hereinto, mutation R882 accounts for 60%. Although the negative effect of DNMT3A on treatment outcome is well known, the prognostic significance of other DNMT3A mutations in AML is still unclear. Here, we tried to determine the incidence and prognostic significance of DNMT3A mutations in a large cohort in Chinese childhood AML.

METHODS

We detected the mutations in DNMT3A exon 23 by polymerase chain reaction and direct sequencing in 342 children with AML (0-16 years old) from January 2005 to June 2013, treated on BCH-2003 AML protocol. The correlation of DNMT3A mutations with clinical characteristics, fusion genes, other molecular anomalies (FLT3 internal tandem duplication [FLT3-ITD], Nucleophosmin 1, C-KIT (KIT proto-oncogene receptor tyrosine kinase), and Wilms tumor 1 mutations), and treatment outcome were analyzed.

RESULTS

DNMT3A mutations were detected in 4 out of 342 (1.2%) patients. Two patients were PML-RARA positive and 1 patient was FLT3-ITD positive. The mutations in coding sequences included S892S, V912A, R885G, and Q886R. Furthermore, there was 1 intronic mutation (c.2739+55A>C) found in 1 patient. No association of DNMT3A mutations with common clinical features was found. Two patients with DNMT3A mutations died of relapse or complications during treatment. One patient gave up treatment due to remission induction failure in day 33. Only 1 patient achieved continuous complete remission.

CONCLUSIONS

DNMT3A mutations were rare in Chinese children with AML including PML-RARA positive APL. The mutation positions were different from the hotspots reported in adult AML. DNMT3A mutations may have adverse impact on prognosis of children with AML.

Expression analysis of BECN1 in acute myeloid leukemia: association with distinct cytogenetic and molecular abnormalities

INTRODUCTION

In acute myeloid leukemia (AML), it has been shown that AML-derived cells often remain sensitive to autophagy-inducing stimuli, leading to the idea that harnessing the autophagy can be pertinent to AML cytotoxic therapy. Despite this promising notion, to date, there is no comprehensive study addressing autophagy-related genes expression status in AML. As a critical mediator, BECN1 influences the onset and advance of autophagy and several studies have pointed to the BECN1 recurrent allelic deletion and expression variation in a broad range of tumors. To explore this caveat, we chose this alteration-prone gene to investigate in our study.

METHODS

We have analyzed the expression status of BECN1 in a series of 128 de novo AML patients using real-time quantitative polymerase chain reaction (qRT-PCR).

RESULTS

In our favorable subgroup, BECN1 expression did not alter (P = 0.301), but in intermediate and unfavorable patients, we have had BECN1 low expression compared to the normal controls (P = 0.008 and P < 0.001, respectively). We found evidence for the association of reduced expression of BECN1 with FLT3-ITD mutation (19 of 27 patients), monosomal karyotype (all of 11 patients), higher age, and WBC count.

CONCLUSION

Overall, remarkable association of reduced expression of BECN1 with FLT3-ITD mutation and monosomal karyotype and their functional relationship is interesting which should be addressed and verified in future studies.