Sterile alpha motif and HD domain-containing protein 1 (SAMHD1) is a mammalian dNTP hydrolase that acts as a negative regulator in the efficacy of cytarabine treatment against acute myeloid leukemia (AML). However, the role of SAMHD1 in AML development and progression remains unknown. We have reported that SAMHD1 knockout (KO) in the AML-derived THP-1 cells results in enhanced proliferation and reduced apoptosis, but the underlying mechanisms are unclear. Here we show that SAMHD1 KO in THP-1 cells increased PI3K activity and reduced expression of the tumor suppressor PTEN. Pharmacological inhibition of PI3K activity reduced cell proliferation specifically in SAMHD1 KO cells, suggesting that SAMHD1 KO-induced cell proliferation is mediated via enhanced PI3K signaling. However, PI3K inhibition did not significantly affect SAMHD1 KO-reduced apoptosis, implicating the involvement of additional mechanisms. SAMHD1 KO also led to enhanced phosphorylation of p27 at residue T157 and its mis-localization to the cytoplasm. Inhibition of PI3K activity reversed these effects, indicating that SAMHD1 KO-induced changes in p27 phosphorylation and localization is mediated via PI3K-Akt signaling. While SAMHD1 KO significantly enhanced THP-1 cell migration in vitro, SAMHD1 KO attenuated the ability of THP-1 cells to form subcutaneous tumors in xenografted immunodeficient mice. This effect correlated with significantly increased expression of tumor necrosis factor α (TNF-α) in tumors, which may suggest that TNF-α-mediated inflammation could account for the decreased tumorigenicity in vivo. Our findings implicate that SAMHD1 can regulate AML cell proliferation via modulation of the PI3K-Akt-p27 signaling axis, and that SAMHD1 may affect tumorigenicity by downregulating inflammation.

MicroRNAs (miRNAs) involved in regulation of the genes. The CCAAT/enhancer-binding protein-α (CEBPα) is a crucial transcription factor for normal hematopoiesis and cell cycle that frequently disrupted in human acute myeloid leukemia (AML). The miR-182 up-regulation in several malignant diseases such as AML was reported, in the other hand bioinformatics analysis revealed CEBPα targeted by miR-182.miR-182-5p inhibition in human acute promyelocytic leukemia (APL) cell line was performed by using locked nucleic acid (LNA) and subsequently miR-182-5p and CEBPα expression, apoptosis, necrosis and cell proliferation were measured. After LNA-anti-miR-182-5p transfection to cells at different time points, miR-182-5p down regulation and CEBPα overexpression was revealed in the LNA-anti-miR group compared to the control groups. The cell viability was meaningfully varied between LNA-anti-miR and control groups. Increasing of the apoptotic ratio was linked to miR-182-5p inhibition in the LNA-anti-miR group rather than other groups. Similarly, the necrotic ratio in the LNA-anti-miR group was higher.Our results supported the hypothesis that miR-182-5p inhibition can reduce the cell viability predominantly due to induces apoptosis and necrosis. The present results can apply in translational medicine for investigation of antisense therapy and drug development in leukemia.

iASPP is a negative regulator of the apoptotic function of p53, and it can enhance the ability of hematopoietic stem cells to self-renew and resist chemo- and radiation therapy. Recent study showed that iASPP could impact the proliferation and apoptosis of leukemia cells by interacting with FHL2. However, whether they have prognostic significance in acute myeloid leukemia (AML) is unknown. Eighty-four AML patients with FHL2 and iASPP expression data from The Cancer Genome Atlas database were enrolled in the study. Patients with high expressions of FHL2 and iASPP had significantly shorter event-free survival (EFS) and overall survival (OS) than patients with low expressions (P = 0.005, P = 0.003, respectively). Univariate analysis indicated that high expressions of FHL2 or iASPP were unfavorable for EFS and OS (all P < 0.05), while multivariate analysis confirmed that high FHL2 expression was an independent risk factor for EFS and OS (all P < 0.05). In patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT), however, EFS and OS were not significantly different between FHL2 or iASPP high- and low-expression groups. Our results suggested that high expressions of FHL2 and iASPP were poor prognostic factors for AML, but the prognostic effect might be overcome by allo-HSCT.

Leukemia stem cells (LSCs) are thought to drive the genesis of acute myeloid leukemia (AML) as well as relapse following chemotherapy. Because of their unique biology, developing effective methods to eradicate LSCs has been a significant challenge. In the present study, we demonstrate that intrinsic overexpression of the mitochondrial dynamics regulator FIS1 mediates mitophagy activity that is essential for primitive AML cells. Depletion of FIS1 attenuates mitophagy and leads to inactivation of GSK3, myeloid differentiation, cell cycle arrest, and a profound loss of LSC self-renewal potential. Further, we report that the central metabolic stress regulator AMPK is also intrinsically activated in LSC populations and is upstream of FIS1. Inhibition of AMPK signaling recapitulates the biological effect of FIS1 loss. These data suggest a model in which LSCs co-opt AMPK/FIS1-mediated mitophagy as a means to maintain stem cell properties that may be otherwise compromised by the stresses induced by oncogenic transformation.

Recently, Long noncoding RNAs (lncRNAs) have been described as regulatory factors for several biological mechanisms through regulating the gene expression. Among them the TNF and HNRNPL related immunoregulatory (THRIL) lncRNA may be involved in the pathogenesis of immune-related and inflammatory disease through controlling the expression of the tumor necrosis factor-alpha (TNF-α) expression. In this case-control study, we investigate the THRIL expression in blood 25 samples of de novo acute myeloid leukemia (AML) cases (10 females and 15 males, mean age±SD: 35.1±3.2 years) in comparison to 50 healthy age and sex matched controls (21 females and 29 males, mean age±SD: 34.9± 3.1) using real-time quantitative reverse transcription-PCR (qRT-PCR) in order to explore any association between THRIL and AML. Our results revealed that there was no significant difference in the expression level of THRIL lncRNA between AML patients and healthy individuals (p=0.2, 95% CI=-0.129-28.35). In addition, there was no significant association between male subgroup and THRIL expression as well as females (p=0.08, 95% CI=-0.197-19.251, p=0.4, 95% CI=-0.185-12.041, respectively). In comparison between control group and FAB classification subtypes of AML patients, there was not any significant association. In conclusion, our study showed that THRIL cannot be used as an informative biomarker for AML diagnosis, however, our results need to be clarify by evolution of more cases.

T cell exhaustion is an immunosuppressive mechanism which occurs in chronic viral infections, solid tumors and hematologic malignancies. Exhausted T cell has increased the expression of inhibitory receptors, and functional impairment. In this study, we investigated the expression from some of those inhibitory receptors being Programmed death 1 (PD-1), T cell immunoglobulin and mucin domain containing molecules 3 (TIM-3) and CD244 on T cells from Iranian acute myeloid leukemia (AML) patients. Peripheral blood samples were collected from Iranian newly diagnosed AML patients and flow cytometric analysis was accomplished for cell surface expression of PD-1, TIM-3, and CD244 on T lymphocytes. Functionality and proliferation assay were done in the presence of anti-PD-1 and anti-CD244 blocking antibodies. Immunophenotyping of T cells showed a significant increase of PD-1 and CD244 expression on CD4+ and CD8+ T cells of AML patients. Whereas blockade of PD1 and CD244 increased the proliferation of CD4+ and CD8+ T lymphocytes of AML patients but IFN-γ production was not significantly increased. In conclusion, our data indicate that CD4+ and CD8+ T cells from AML patients appeared to be exhausted and blockade of some immune checkpoints can improve the proliferation of those cells.

This study examines the long-term OS of relapsed AML patients who were enrolled to 9 successive ECOG-ACRIN trials for newly diagnosed AML, during 1984-2008. The objectives were to examine whether there is a trend of improvement in the survival of relapsed AML patients in the more recent studies and to search for prognostic factors that are associated with long-term OS after relapse. A total of 3,012 patients were enrolled, 1,779(59.1%) achieved CR1 and of these, 58.9% relapsed. The median follow-up was 9.7 years. The median OS from relapse was 0.5 years and the 5-year OS was 10(±1)%. These results were similar even for the most recent studies. A multivariate model showed that age (p<0.001), cytogenetics at diagnosis, duration of CR1 (p<0.001) and undergoing allogeneic transplantation were significantly associated with OS from relapse. Even among patients who relapsed with better prognostic factors; age<40 and CR1>12 months, there was no significant OS difference between the studies (p=0.48). In conclusion, this large cohort appears to confirm that the survival of AML patients post-relapse continues to be dismal and has not improved during the past quarter of a century. This article is protected by copyright. All rights reserved.

The aim of the current study was to measure the expression of acetyl-N-Ser-Asp-Lys-Pro (ACSDKP) in patients with acute myeloid leukemia (AML) and the effect of prolyl oligopeptidase inhibitor (POPi) on the bone marrow stromal cells of these patients. Serum and bone marrow stromal cell samples were collected from 33 patients with AML admitted to Wuxi Second People's Hospital, Nanjing Medical University between September 2011 and August 2016. ACSDKP levels were measured using a highly specific competitive enzyme immunoassay (EIA). Bone marrow stromal cells were treated with synthetic ACSDKP (10 µM/ml) or different concentrations of POPi S17092 (25, 50 and 100 µg/ml). Cells that received no treatment were used as control. An MTT assay was conducted to measure the proliferation of bone marrow stromal cells. The results demonstrated that serum levels of ACSDKP in patients with AML were significantly higher than those of controls (P<0.05). Following treatment with ACSDKP, cell proliferation was significantly increased compared with untreated cells (P<0.05). However, following treatment with different concentrations of POPi, the expression of ACSDKP was significantly decreased in a dose-dependent manner (P<0.05). Furthermore, the proliferation of bone marrow stromal cells was also decreased in a dose-dependent manner. Therefore, the present study demonstrated that ACSDKP levels were increased in the serum and bone marrow stromal cells of patients with AML and that ACSDKP promoted the proliferation of bone marrow stromal cells of these patients, which was inhibited by POPi. These results may identify a novel target for the treatment of AML.

The mutational spectrum and prognostic stratification of intermediate-risk acute myeloid leukemia (IR-AML), which accounts for a substantial number of AML, are unclear. In order to explore the prognostic significance of the mutational spectrum in IR-AML, 106 IR-AML patients were collected from The Cancer Genome Atlas database. Sixty-two patients underwent chemotherapy-only, forty-four proceeded to allogeneic hematopoietic stem cell transplantation (allo-HSCT). Fifty-five patients had more than five recurrent genetic mutations. NPM1 had the highest mutation frequency, followed by DNMT3A, FLT3, RUNX1, IDH2, IDH1, and TET2. In all patients, allo-HSCT was an independent favorable factor for EFS and OS (P = 0.036, P = 0.001, respectively); age ≥60 years, FLT3-ITD and mutations in DNMT3A and RUNX1 were independent risk factors for survival (all P < 0.05). In the chemotherapy-only group, multivariate analysis showed that age ≥60 years was an independent risk factor for EFS and OS (P = 0.008, P = 0.017, respectively). In the allo-HSCT group, multivariate analysis indicated that MLL-PTD was an independent risk fact for EFS (P = 0.037), FLT3-ITD and RUNX1 mutations independently contributed to poor OS (P = 0.035, P = 0.014, respectively). In conclusion, older age was an important risk factor for IR-AML patients undergoing chemotherapy-only; FLT3-ITD, MLL-PTD and RUNX1 mutations were significant risk factors for IR-AML patients who received allo-HSCT.