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.

Lower Levels of TET2 Gene Expression, with a Higher Level of TET2 Promoter Methylation in Patients with AML; Evidence for the Role of Aberrant Methylation in AML Pathogenesis.

DNA methylation is a key epigenetic mechanism that is dysregulated in leukemia and plays a significant role in leukemogenesis. Ten-eleven translocation 2 (TET2) is one of the most frequently mutated genes among the DNA methylation regulators in hematologic malignancies, indicating its tumor-suppressor function. In this study, we investigated the expression and methylation status of TET2 in patients with AML. Quantitative RT-PCR was used to evaluate TET2 expression in peripheral blood mononuclear cells (PBMCs) from 51 newly diagnosed AML patients and 50 healthy controls. The methylation-sensitive high-resolution melting (MS-HRM) method was used in 45 patients with AML and 15 healthy controls to evaluate the promoter methylation of TET2. TET2 expression was significantly downregulated (P < 0.0001) in patients with AML compared to that in healthy controls. Furthermore, the methylation level of the TET2 promoter was significantly different between patients and controls. Aberrant methylation of the TET2 promoter was observed in 53.3% of the patients. Interestingly, a negative (- 0.3138) and significant (P = 0.0358) correlation between TET2 methylation and expression was found. The survival of patients with downregulated TET2 was poorer than that of other patients. TET2 gene expression was significantly downregulated while the promoter methylation was higher in patients, indicating that TET2 may be a tumor suppressor gene and a prognostic factor in AML and that transcriptional silencing of the TET2 gene may play a role in AML pathogenesis. Since epigenetic mechanisms are reversible, abnormal TET2 methylation could become a therapeutic target in the future.