DNMT3A mutations are frequently discovered in acute myeloid leukemia (AML), associated with poor outcome. Recently, a relapse case report of AML extramedullary disease has showed that AML cells harboring DNMT3A variation were detected in the cerebral spinal fluid. However, whether a causal relationship exists between DNMT3A mutation (D3Amut) and extramedullary infiltration (EMI) is unclear. We took advantage of DNMT3A (R882C) mutation-carrying AML cell strain, that is, OCI-AML3, assessing its migration ability in vitro and in vivo. By RNA interfering technology and a xenograft mouse model, we evaluated the effect of DNMT3A mutation on cell mobility and explored the possible mechanism. OCI-AML3 displayed extraordinary migration ability in vitro and infiltrated into meninges of NOD/SCID mice after intravenous transfusion. We found that this leukemic migration or infiltration capacity was significantly compromised by the knockdown of DNMT3A mutant. Notably, TWIST1, a critical inducer of epithelial–mesenchymal transition, which underlies the metastasis of carcinomas, was highly expressed in association with R882 mutations. Abrogation of TWIST1 in DNMT3A mutated cells considerably weakened their mobility or infiltration. Our results demonstrate that D3Amut in OCI-AML3 strain enhances leukemic aggressiveness by promoting EMI process, which is partially through upregulating TWIST1.

Acute myeloid leukemia (AML) with retinoic acid receptor γ (RARG) rearrangement has clinical, morphologic, and immunophenotypic features similar to classic acute promyelocytic leukemia. However, AML with RARG rearrangement is insensitive to alltrans retinoic acid (ATRA) and arsenic trioxide (ATO) and carries a poor prognosis. We initiated a global cooperative study to define the clinicopathological features, genomic and transcriptomic landscape, and outcomes of AML with RARG rearrangements collected from 29 study groups/institutions worldwide. Thirty-four patients with AML with RARG rearrangements were identified. Bleeding or ecchymosis was present in 18 (54.5%) patients. Morphology diagnosed as M3 and M3v accounted for 73.5% and 26.5% of the cases, respectively. Immunophenotyping showed the following characteristics: positive for CD33, CD13, and MPO but negative for CD38, CD11b, CD34, and HLA-DR. Cytogenetics showed normal karyotype in 38% and t(11;12) in 26% of patients. The partner genes of RARG were diverse and included CPSF6, NUP98, HNRNPc, HNRNPm, PML, and NPM1. WT1- and NRAS/KRAS-mutations were common comutations. None of the 34 patients responded to ATRA and/or ATO. Death within 45 days from diagnosis occurred in 10 patients (∼29%). At the last follow-up, 23 patients had died, and the estimated 2-year cumulative incidence of relapse, event-free survival, and overall survival were 68.7%, 26.7%, and 33.5%, respectively. Unsupervised hierarchical clustering using RNA sequencing data from 201 patients with AML showed that 81.8% of the RARG fusion samples clustered together, suggesting a new molecular subtype. RARG rearrangement is a novel entity of AML that confers a poor prognosis. This study is registered with the Chinese Clinical Trial Registry (ChiCTR2200055810).

Acute myeloid leukemia (AML) with an NPM1 mutation (NPMc+) has a distinct gene expression signature and displays molecular abnormalities similar to mixed lineage leukemia (MLL), including aberrant expression of the PBX3 and HOXA gene cluster. However, it is unclear if the aberrant expression of PBX3 and HOXA is essential for the survival of NPM1-mutated leukemic cells.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by a novel bunyavirus named SFTS virus (SFTSV), which is classified into the genus Phlebovirus and family Phenuiviridae. Reactive plasmacytosis mimicking multiple myeloma is a very rare condition in association with SFTS. Here, we describe two SFTS cases who presented with hyperimmunoglobulinemia, as well as extensive bone marrow and peripheral blood plasmacytosis, which mimicked multiple myeloma (MM). We report two cases who presented with fever and blood routine abnormity which were conformed as SFTS eventually. They were performed bone marrow aspiration and were admitted to the department of hematology with a preliminary diagnosis of MM. They all had hyperimmunoglobulinemia, extensive bone marrow and peripheral blood plasma cells, prolonged activated partial thromboplastin time (APTT), elevated hepatic enzyme. The two patients recovered with treatment of doxycycline, human immunoglobulins, plasma transfusion, and other supporting treatments. But case 1 occurred lymphoma 8 months later and died. SFTS might be one of differential diagnosis of MM in certain endemic area. We also conclude that SFTSV is a pantropic virus that could injure most tissues and cells of the human body.

DNA methyltransferase 3A (DNMT3A) catalyzes de novo DNA methylation and plays important roles in the pathogenesis of acute myeloid leukemia. However, the expression status of DNMT3A variants in acute myeloid leukemia remains obscure. This study aimed to assess the expression levels of alternative splicing of DNMT3A variants and explore their roles in acute myeloid leukemia (AML). DNMT3A variants gene expression were assessed, measuring their effects on cell proliferation. In addition, the expression of DNMT3A variants were evaluated in acute myeloid leukemia patients. Four DNMT3A variants were identified, with DNMT3A1 and DNMT3A2V found to be dominant in acute myeloid leukemia cell lines. Moreover, DNMT3A2V overexpression delayed cell proliferation; while, DNMT3A2V R882H mutation promoted cell proliferation. Further, DNMT3A1 and DNMT3A2V were detected in newly diagnosed acute myeloid leukemia (AML) patients and controls with non-malignant hematological disease, with DNMT3A2V significantly up-regulated in AML patients. The main transcript switched from DNMT3A1 to DNMT3A2V in some patients, especially the low risk group based on the NCCN 2016 guidelines. These findings suggest that DNMT3A1 and DNMT3A2V are the main variants in acute myeloid leukemia with different clinical association, and might play important roles in the pathophysiology of acute myeloid leukemia.