Retroviral integration at the Epi1 locus cooperates with Nf1 gene loss in the progression to acute myeloid leukemia

Juvenile myelomonocytic leukemia (JMML) is a disease that occurs in young children and is associated with a high mortality rate. In most patients, JMML has a progressive course leading to death by virtue of infection, bleeding, or progression to acute myeloid leukemia (AML). As it is known that children with neurofibromatosis type 1 syndrome have a markedly increased risk of developing JMML, we have previously developed a mouse model of JMML through reconstitution of lethally irradiated mice with hematopoietic stem cells homozygous for a loss-of-function mutation in the Nf1 gene (D. L. Largaespada, C. I. Brannan, N. A. Jenkins, and N. G. Copeland, Nat. Genet. 12:137-143, 1996). In the course of these experiments, we found that all these genetically identical reconstituted mice developed a JMML-like disorder, but only a subset went on to develop more acute disease. This result strongly suggests that additional genetic lesions are responsible for disease progression to AML. Here, we describe the production of a unique tumor panel, created using the BXH-2 genetic background, for identification of these additional genetic lesions. Using this tumor panel, we have identified a locus, Epi1, which maps 30 to 40 kb downstream of the Myb gene and appears to be the most common site of somatic viral integration in BXH-2 mice. Our findings suggest that proviral integrations at Epi1 cooperate with loss of Nf1 to cause AML.     

Overexpression miR-520a-3p inhibits acute myeloid leukemia progression via targeting MUC1

BackgroundAcute myeloid leukemia (AML) is one of the familiar malignant tumors in the hematological system. miR-520a-3p is reported to be involved in several cancers’ progression. However, miR-520a-3p role in AML remains unclear. In this study, we aimed to clarify the role and potential mechanism of miR-520a-3p in AML.MethodsCell viability, proliferation, cycle and apoptosis were detected by MTT assay, colony formation assay, flow cytometry, respectively. The levels of PNCA, Bcl-2, Cleaved caspase 3, Cleaved caspase 9 and β-catenin protein were detected by Western blot. Dual-luciferase reported assay was performed to detect the regulation between miR-520a-3p and MUC1. To verify the effect of miR-520a-3p on tumor proliferation in vivo, a non-homogenous transplant model of tumors was established.ResultsmiR-520a-3p expression was down-regulated, and MUC1 expression was up-regulated in AML patients. miR-520a-3p overexpression suppressed THP-1 cell proliferation, induced cell cycle G0/G1 inhibition and promoted apoptosis. miR-520a-3p targeted MUC1 and negatively regulated its expression. MUC1 knockdown inhibited THP-1 cell proliferation and promoted apoptosis. miR-520a-3p overexpression inhibited AML tumors growth.ConclusionOverexpression miR-520a-3p inhibited AML cell proliferation, and promoted apoptosis via inhibiting MUC1 expression and repressing Wnt/β-catenin pathway activation.     

ATF3 coordinates serine and nucleotide metabolism to drive cell cycle progression in acute myeloid leukemia

1. Download : Download high-res image (170KB)
2. Download : Download full-size image

     

CSF3R,SETBP1 and CALR mutations in chronic neutrophilic leukemia

The WHO 2008 definition of chronic neutrophilic leukemia (CNL) is based on clinical and laboratory parameters but not on molecular abnormalities. Mutations in CSF3R, SETBP1 and CALR are reported in patients with chronic neutrophilic leukemia (CNL). However, because CNL is rare, there are few large studies of this issue. We sequenced these genes in 14 patients who met the WHO-criteria of CNL. 8 subjects had CSF3R ^T618I , 6 SETBP1 mutations and 1 a CALR mutation. Our data suggest mutation analysis of CSF3R, SETBP1 and CALR should be included in the diagnostic criteria for CNL. These data may also have therapy implications.     

Wogonoside impedes the progression of acute myeloid leukemia through inhibiting bone marrow angiogenesis

Decreasing bone marrow (BM) microvessel density and circulating angiogenic cytokine levels are promising strategies for the treatment of relapsed and resistant acute myeloid leukemia (AML). Previous studies have reported that wogonoside could inhibit the progression of AML and suppress angiogenesis in a solid tumor, but the correlation of these two effects was ignored. In this research, we determined whether wogonoside could inhibit angiogenesis in this hematologic malignancy. We found that wogonoside could inhibit tumor growth and progression, and prolong the survival of nude mice inoculated with U937/MDR. Besides, reducing BM angiogenesis might cause therapeutic effect against resistant AML. Therefore, coculture between AML cells and BM stromal cells was established to imitate their crosstalk. Then, the effect of wogonoside on BM angiogenesis was tested in vitro and in vivo. We found that wogonoside could suppress microvessel formation in the chicken chorioallantoic membrane assay model and matrigel plug assay. The mechanism research revealed that wogonoside could block the JAK2-STAT3 pathway in AML cells and stromal cells to break their positive feedback. We detected several cytokines related to AML or angiogenesis and found that secreted interleukin-8 was a significant angiogenic cytokine to induce BM angiogenesis. These findings supported that new diagnostics and promising treatment strategies could be developed in relapsed and resistant AML patients.     

Morphometric analysis of myelofibrosis in agnogenic myeloid metaplasia and chronic myelogenous leukemia.

A morphometric analysis of bone marrow biopsy specimens from patients with myelofibrosis was made to determine the amount of lattice fiber and the number of megakaryocytes, to compare the degree of myelofibrosis in primary and secondary myelofibrosis, and to assess the relationship between the morphometric findings and other parameters. Eight patients with agnogenic myeloid metaplasia (AMM) and six with chronic myelogenous leukemia associated with frank myelofibrosis (CML-MF) were studied. When the main clinical, hematological, and laboratory features of both groups of patients were compared, the only significant difference was in the neutrophil alkaline phosphatase score. Morphometric study showed that the amount of lattice fiber and the number of megakaryocytes in AMM were not statistically different from those in CML-MF, and that neither the number of megakaryocytes nor the platelet count correlated with the amount of lattice fiber.     

Dihydromyricetin sensitizes human acute myeloid leukemia cells to retinoic acid-induced myeloid differentiation by activating STAT1

The success of all-trans retinoic acid (ATRA) in differentiation therapy for patients with acute promyelocytic leukemia (APL) highly encourages researches to apply a new combination therapy based on ATRA. Therefore, research strategies to further sensitize cells to retinoids are urgently needed. In this study, we showed that Dihydromyricetin (DMY), a 2,3-dihydroflavonol compound, exhibited a strong synergy with ATRA to promote APL NB4 cell differentiation. We observed that DMY sensitized the NB4 cells to ATRA-induced cell growth inhibition, CD11b expression, NBT reduction and myeloid regulator expression. PML-RARα might not be essential for DMY-enhanced differentiation when combined with ATRA, while the enhanced differentiation was dependent on the activation of p38-STAT1 signaling pathway. Taken together, our study is the first to evaluate the synergy of DMY and ATRA in NB4 cell differentiation and to assess new opportunities for the combination of DMY and ATRA as a promising approach for future differentiation therapy.     

Annular promyelocytes in acute myeloid leukemia

Granulocytes with ring-shaped nuclei (annular granulocytes; ring granulocytes) are normal bone marrow constituents in rodents. Studies in man have shown a small number of these cells in cases of myeloproliferative diseases. Myelocytes and metamyelocytes have also been described. Similar to rodents and some other animal species, the annular promyelocyte also exists in humans. The significance of these very rare cells in human haemopoiesis becomes an interesting question.     

Interleukin-17 in acute myeloid leukemia

There are several reports that angiogenesis plays important roles in hematological malignancies including acute myeloid leukemia (AML). Human interleukin-17 (IL-17) is a proinflammatory cytokine produced by activated CD4 T cells. IL-17 plays a potential role in T cell mediated angiogenesis. The role of IL-17 in pathologic angiogenesis has not been evaluated yet. The aim of the study was to determine plasma level of IL-17 in patients with AML. IL-17 levels were measured by ELISA in plasma samples taken from 68 adult patients with AML before chemotherapy was administered. In addition 20 out of 68 patients were reanalysed after achieving complete remission (CR). Ten samples from healthy volunteers were evaluated as the control. In this study we have demonstrated that serum level of IL-17 is not elevated in AML patients. These results suggest that angiogenesis in AML is not mediated by CD4 T cells. To our knowledge this is the first report about IL-17 serum level in acute leukemias. We are currently evaluating IL-17 levels in others haematological malignancies.     

Preferential loss of mismatch repair function in refractory and relapsed acute myeloid leukemia： potential contribution to AML proqression

Acute myeloid leukemia （AML） is an aggressive hematological cancer. Despite therapeutic regimens that lead to complete remission, the vast majority of patients undergo relapse. The molecular mechanisms underlying AML development and relapse remain incompletely defined. To explore whether loss of DNA mismatch repair （MMR） function is involved in AML, we screened two key MMR genes, MSH2 and MLH1, for mutations and promoter hypermethylation in leukemia specimens from 53 AML patients and blood from 17 non-cancer controls. We show here that whereas no amino acid alteration or promoter hypermethylation was detected in all control samples, 18 AML patients exhibited either mutations in MMR genes or hypermethylation in the MLH1 promoter. In vitro functional MMR analysis revealed that almost all the mutations analyzed resulted in loss of MMR function. MMR defects were significantly more frequent in patients with refractory or relapsed AML compared with newly diagnosed patients. These observations suggest for the first time that the loss of MMR function is associated with refractory and relapsed AML and may contribute to disease Datho8enesis.     

Epigenetic dysregulation of ID4 predicts disease progression and treatment outcome in myeloid malignancies

Promoter hypermethylation‐mediated inactivation of ID4 plays a crucial role in the development of solid tumours. This study aimed to investigate ID4 methylation and its clinical relevance in myeloid malignancies. ID4 hypermethylation was associated with higher IPSS scores, but was not an independent prognostic biomarker affecting overall survival (OS) in myelodysplastic syndrome (MDS). However, ID4 hypermethylation correlated with shorter OS and leukaemia‐free survival (LFS) time and acted as an independent risk factor affecting OS in acute myeloid leukaemia (AML). Moreover, ID4 methylation was significantly decreased in the follow‐up paired AML patients who achieved complete remission (CR) after induction therapy. Importantly, ID4 methylation was increased during MDS progression to AML and chronic phase (CP) progression to blast crisis (BC) in chronic myeloid leukaemia (CML). Epigenetic studies showed that ID4 methylation might be one of the mechanisms silencing ID4 expression in myeloid leukaemia. Functional studies in vitro showed that restoration of ID4 expression could inhibit cell proliferation and promote apoptosis in both K562 and HL60 cells. These findings indicate that ID4 acts as a tumour suppressor in myeloid malignancies, and ID4 methylation is a potential biomarker in predicting disease progression and treatment outcome.     

The frequency of NPM1 mutations in childhood acute myeloid leukemia

Leser-Trélat syndrome is characterized by the eruptive appearance of multiple seborrheic keratoses in association with underlying malignant disease. Usually, the sign of Leser-Trélat is associated with adenocarcinoma, most frequently of the colon, breast, or stomach, but also of the lung, kidney, liver, and pancreas. Herein, we present a case that we believe is the first report of the sign of Leser-Trélat in association with occult gastric adenocarcinoma and the anamnestic oncologic history of five other multiple primitive cancers. Epidermal growth factor receptor (EGFR) immunohistochemical expression analysis of multiple seborrheic keratoses revealed an intense membranous staining in the basal keratinocytes and in all the upper epidermal layers. Patients with the sign of Leser-Trélat should undergo a diagnostic screening programme for malignant disease along with patients with known Leser-Trélat syndrome who present with a recent acute and florid eruption of their seborrheic keratoses. We propose the importance of combining the molecular features of multiple seborrheic keratoses with EGFR immunohistochemistry analyses to determine the likelihood of Leser-Trélat syndrome and the consequent high risk of underlying multiple visceral malignancies.     

Dendritic cell vaccination in acute myeloid leukemia

The prognosis of patients with acute myeloid leukemia (AML) remains dismal, with a 5-year overall survival rate of only 5.2% for the continuously growing subgroup of AML patients older than 65 years. These patients are generally not considered eligible for intensive chemotherapy and/or allogeneic hematopoietic stem cell transplantation because of high treatment-related morbidity and mortality, emphasizing the need for novel, less toxic, treatment alternatives. It is within this context that immunotherapy has gained attention in recent years. In this review, we focus on the use of dendritic cell (DC) vaccines for immunotherapy of AML. DC are central orchestrators of the immune system, bridging innate and adaptive immunity and critical to the induction of anti-leukemic immunity. We discuss the rationale and basic principles of DC-based therapy for AML and review the clinical experience that has been obtained so far with this form of immunotherapy for patients with AML.