Acute myelogenous leukemia

Synergistic cooperation between ABT-263 and MEK1/2 inhibitor: effect on apoptosis and proliferation of acute myeloid leukemia cells

In spite of intensive research to improve treatment of acute myeloid leukemia (AML) more than half of all patients continue to develop a refractory disease. Therefore there is need to improve AML treatment. The overexpression of the BCL-2 family anti-apoptotic members, like BCL-2 or BCL-xL has been largely reported in lymphoid tumors but also in AML and other tumors. To counteract the anti-apoptotic effect of BCL-2, BH3 mimetics have been developed to target cancer cells. An increase in activity of ERK1/2 mitogen activated protein (MAP) kinase has also been reported in AML and might be targeted by MEK1/2 inhibitors. Hence, in the current work, we investigated whether the association of a BH3 mimetic such ABT-263 and the MEK1/2 inhibitor pimasertib (MEKI), was efficient to target AML cells. A synergistic increasing of apoptosis was observed in AML cell lines and in primary cells without affecting normal bone marrow cells. Such cooperation was confirmed on tumor growth in a mouse xenograft model of AML. In addition we demonstrated that MEKI sensitized the cells to apoptosis through its ability to promote a G1 cell cycle arrest. So, this combination of a MAP Kinase pathway inhibitor and a BH3 mimetic could be a promising strategy to improve the treatment of AML.

The Prognostic Value of D-Dimer in De Novo Acute Myeloid Leukemia

BACKGROUND

The aim of this study was to evaluate the prognostic value of D-dimer in patients with newly diagnosed de novo non-M3 subtypes of acute myeloid leukemia (AML).

MATERIALS AND METHODS

We retrospectively analyzed the clinical data from 245 patients with newly diagnosed de novo non-M3 subtypes of AML at the Tongji Hospital from January 2010 to December 2014.

RESULTS

The comparison results indicated that the D-dimer values were higher in patients with AML with the following characteristics: WBC count ≥ 20 × 10(9)/L (2.20 versus 6.00, P = 0.001), percentage of bone marrow (BM) blasts ≥ 60% (2.06 versus 5.69, P = 0.003), and poor-risk stratification (P < 0.001). Cox univariate regression analysis showed that overall survival was negatively affected by the following factors: age > 60 years, poor-risk stratification, BM blast cell count ≥60%, and D-dimer ≥1μg/mL. Multivariate analysis showed that only age > 60 years (P < 0.001), BM blast cell counts ≥60% (P = 0.001) and D-dimer values ≥1μg/mL (P = 0.014) were independent adverse prognostic factors.

CONCLUSIONS

D-dimer ≥1μg/mL is related to high tumor burden and can be considered as an independent prognostic factor in patients with de novo non-M3 AML.

Selective AKR1C3 Inhibitors Potentiate Chemotherapeutic Activity in Multiple Acute Myeloid Leukemia (AML) Cell Lines

We report the design, synthesis, and evaluation of potent and selective inhibitors of aldo-keto reductase 1C3 (AKR1C3), an important enzyme in the regulatory pathway controlling proliferation, differentiation, and apoptosis in myeloid cells. Combination treatment with the nontoxic AKR1C3 inhibitors and etoposide or daunorubicin in acute myeloid leukemia cell lines, elicits a potent adjuvant effect, potentiating the cytotoxicity of etoposide by up to 6.25-fold and the cytotoxicity of daunorubicin by >10-fold. The results validate AKR1C3 inhibition as a common adjuvant target across multiple AML subtypes. These compounds in coadministration with chemotherapeutics in clinical use enhance therapeutic index and may avail chemotherapy as a treatment option to the pediatric and geriatric population currently unable to tolerate the side effects of cancer drug regimens.

Proteolytic systems and AMP-activated protein kinase are critical targets of acute myeloid leukemia therapeutic approaches

The therapeutic strategies against acute myeloid leukemia (AML) have hardly been modified over four decades. Although resulting in a favorable outcome in young patients, older individuals, the most affected population, do not respond adequately to therapy. Intriguingly, the mechanisms responsible for AML cells chemoresistance/susceptibility are still elusive. Mounting evidence has shed light on the relevance of proteolytic systems (autophagy and ubiquitin-proteasome system, UPS), as well as the AMPK pathway, in AML biology and treatment, but their exact role is still controversial. Herein, two AML cell lines (HL-60 and KG-1) were exposed to conventional chemotherapeutic agents (cytarabine and/or doxorubicin) to assess the relevance of autophagy and UPS on AML cells’ response to antileukemia drugs. Our results clearly showed that the antileukemia agents target both proteolytic systems and the AMPK pathway. Doxorubicin enhanced UPS activity while drugs’ combination blocked autophagy specifically on HL-60 cells. In contrast, KG-1 cells responded in a more subtle manner to the drugs tested consistent with the higher UPS activity of these cells. In addition, the data demonstrates that autophagy may play a protective role depending on AML subtype. Specific modulators of autophagy and UPS are, therefore, promising targets for combining with standard therapeutic interventions in some AML subtypes.

CBFβ-SMMHC creates aberrant megakaryocyte-erythroid progenitors prone to leukemia initiation in mice

Acute myeloid leukemia (AML) arises through multistep clonal evolution characterized by stepwise accumulation of successive alterations affecting the homeostasis of differentiation, proliferation, self-renewal, and survival programs. The persistence and dynamic clonal evolution of leukemia-initiating cells and preleukemic stem cells during disease progression and treatment are thought to contribute to disease relapse and poor outcome. Inv(16)(p13q22) or t(16;16)(p13.1;q22), one of the most common cytogenetic abnormalities in AML, leads to expression of a fusion protein CBFβ-SMMHC (CM) known to disrupt myeloid and lymphoid differentiation. Anemia is often observed in AML but is presumed to be a secondary consequence of leukemic clonal expansion. Here, we show that CM expression induces marked deficiencies in erythroid lineage differentiation and early preleukemic expansion of a phenotypic pre-megakaryocyte/erythrocyte (Pre-Meg/E) progenitor population. Using dual-fluorescence reporter mice in lineage tracking and repopulation assays, we show that CM expression cell autonomously causes expansion of abnormal Pre-Meg/E progenitors with compromised erythroid specification and differentiation capacity. The preleukemic Pre-Meg/Es display dysregulated erythroid and megakaryocytic fate-determining factors including increased Spi-1, Gata2, and Gfi1b and reduced Zfpm1, Pf4, Vwf, and Mpl expression. Furthermore, these abnormal preleukemic Pre-Meg/Es have enhanced stress resistance and are prone to leukemia initiation upon acquiring cooperative signals. This study reveals that the leukemogenic CM fusion protein disrupts adult erythropoiesis and creates stress-resistant preleukemic Pre-Meg/E progenitors predisposed to malignant transformation. Abnormality in Meg/E or erythroid progenitors could potentially be considered an early predictive risk factor for leukemia evolution.

Inside HDACs with more selective HDAC inhibitors

Inhibitors of histone deacetylases (HDACs) are nowadays part of the therapeutic arsenal mainly against cancers, with four compounds approved by the Food and Drug Administration. During the last five years, several groups have made continuous efforts to improve this class of compounds, designing more selective compounds or compounds with multiple capacities. After a survey of the HDAC biology and structures, this review summarizes the results of the chemists working in this field, and highlights when possible the behavior of the molecules inside their targets.

Resistance to chemotherapy is associated with altered glucose metabolism in acute myeloid leukemia

Altered glucose metabolism has been described as a cause of chemoresistance in multiple tumor types. The present study aimed to identify the expression profile of glucose metabolism in drug-resistant acute myeloid leukemia (AML) cells and provide potential strategies for the treatment of drug-resistant AML. Bone marrow and serum samples were obtained from patients with AML that were newly diagnosed or had relapsed. The messenger RNA expression of hypoxia inducible factor (HIF)-1α, glucose transporter (GLUT)1, and hexokinase-II was measured by quantitative polymerase chain reaction. The levels of LDH and β subunit of human F1-F0 adenosine triphosphate synthase (β-F1-ATPase) were detected by enzyme-linked immunosorbent and western blot assays. The HL-60 and HL-60/ADR cell lines were used to evaluate glycolytic activity and effect of glycolysis inhibition on cellular proliferation and apoptosis. Drug-resistant HL-60/ADR cells exhibited a significantly increased level of glycolysis compared with the drug-sensitive HL-60 cell line. The expression of HIF-1α, hexokinase-II, GLUT1 and LDH were increased in AML patients with no remission (NR), compared to healthy control individuals and patients with complete remission (CR) and partial remission. The expression of β-F1-ATPase in patients with NR was decreased compared with the expression in the CR group. Treatment of HL-60/ADR cells with 2-deoxy-D-glucose or 3-bromopyruvate increased in vitro sensitivity to Adriamycin (ADR), while treatment of HL-60 cells did not affect drug cytotoxicity. Subsequent to treatment for 24 h, apoptosis in these two cell lines showed no significant difference. However, glycolytic inhibitors in combination with ADR increased cellular necrosis. These findings indicate that increased glycolysis and low efficiency of oxidative phosphorylation may contribute to drug resistance. Targeting glycolysis is a viable strategy for modulating chemoresistance in AML.

[Molecular mechanisms of niclosamide antitumor activity]

In this review the recent data regarding the antitumor activity of niclosamide and the molecular mechanisms of its antitumor activity are presented. Niclosamide has been used in the clinic for the treatment of intestinal parasite infections. In recent years in several screening investigations of various drugs and chemical compounds niclosamide was identified as a potential anticancer agent. Niclosamide not only inhibits the Wnt/β-catenin, mTORC1, STAT3, NF-κB and Notch signaling pathways, but also targets mitochondria in cancer cells to induce growth inhibition and apoptosis. A number of studies have established the anticancer activity of niclosamide in both in vitro and in vivo in xenotransplantation models using human tumors and immunodeficient mice. It is important that niclosamide is active not only against tumor cells but also cancer stem cells. Normal cells are resistant to niclosamide. The accumulated experimental data suggest niclosamide is a promising drug for the treatment of various types of cancer.

Cellular Reprogramming Allows Generation of Autologous Hematopoietic Progenitors From AML Patients That Are Devoid of Patient-Specific Genomic Aberrations

Current treatments that use hematopoietic progenitor cell (HPC) transplantation in acute myeloid leukemia (AML) patients substantially reduce the risk of relapse, but are limited by the availability of immune compatible healthy HPCs. Although cellular reprogramming has the potential to provide a novel autologous source of HPCs for transplantation, the applicability of this technology toward the derivation of healthy autologous hematopoietic cells devoid of patient-specific leukemic aberrations from AML patients must first be evaluated. Here, we report the generation of human AML patient-specific hematopoietic progenitors that are capable of normal in vitro differentiation to myeloid lineages and are devoid of leukemia-associated aberration found in matched patient bone marrow. Skin fibroblasts were obtained from AML patients whose leukemic cells possessed a distinct, leukemia-associated aberration, and used to create AML patient-specific induced pluripotent stem cells (iPSCs). Through hematopoietic differentiation of AML patient iPSCs, coupled with cytogenetic interrogation, we reveal that AML patient-specific HPCs possess normal progenitor capacity and are devoid of leukemia-associated mutations. Importantly, in rare patient skin samples that give rise to mosaic fibroblast cultures that continue to carry leukemia-associated mutations; healthy hematopoietic progenitors can also be generated via reprogramming selection. Our findings provide the proof of principle that cellular reprogramming can be applied on a personalized basis to generate healthy HPCs from AML patients, and should further motivate advances toward creating transplantable hematopoietic stem cells for autologous AML therapy. Stem Cells2013;33:1839–1849

Deoxycytidine kinase is downregulated under hypoxic conditions and confers resistance against cytarabine in acute myeloid leukaemia

OBJECTIVES

Leukaemia initiating cells reside within specialised niches in the bone marrow where they undergo complex interactions with different stromal cell types. The bone marrow niche is characterised by a low oxygen content resulting in high expression of hypoxia-inducible factor 1 α in leukaemic cells conferring a negative prognosis to patients with acute myeloid leukaemia (AML).

METHODS AND RESULTS

In the current study, we investigated the impact of hypoxic vs. normoxic conditions on the sensitivity of AML cell lines and primary AML blasts to cytarabine. AML cells cultured under 6% oxygen were significantly more resistant against cytarabine compared to cells cultured under normoxic conditions in proliferation and colony-formation assays. Interestingly upon cultivation under hypoxia, the expression of the cytarabine-activating enzyme deoxycytidine kinase was downregulated in all analysed AML cell lines and primary AML samples representing a possible mechanism for resistance to chemotherapy. Furthermore, the downregulation of deoxycytidine kinase could be associated with hypoxia-inducible factor 1 α as treatment with its inhibitor BAY87-2243 hampered the downregulation of deoxycytidine kinase expression under hypoxic conditions.

CONCLUSIONS

In conclusion, our data reveal that hypoxia-induced downregulation of deoxycytidine kinase represents one stroma-cell-independent mechanism of drug resistance to cytarabine in acute myeloid leukaemia.

Blockage of miR-92a-3p with locked nucleic acid induces apoptosis and prevents cell proliferation in human acute megakaryoblastic leukemia

MicroRNAs (miRNAs) are non-coding RNAs involved in post-transcriptional regulation of gene expression. In many cancers, up- or downregulation of different miRNAs is reported. In acute myeloid leukemia, upregulation of miR-92a-3p was reported in human in vitro studies. We performed blockage of miR-29a-3p in human acute megakaryoblastic leukemia cell line (M-07e) by using locked nucleic acid (LNA) and cell proliferation; apoptosis and necrosis were assessed. At different time points after LNA-anti-miR92a-3p transfection, miR-92a-3p quantitation was assessed by qRT-real-time PCR, MTT assay and annexin/propidium iodide staining were performed. The data were processed using the ANOVA test. At all three time points, the expression of miR-92a-3p was lower in the LNA-anti-miR group compared with the control groups. Cell viability between LNA-Anti-miR and the control group was statistically significant. Blockage of miR-92a-3p was associated with increment of the ratio of apoptotic cells in the LNA-anti-miR group was higher than the other group. The ratio of necrotic cells in the LNA-antimiR group was higher than the other groups. These assessments indicate that miR-92a-3p blockage can decrease the viability of M-07e cells, which is mainly due to induction of apoptosis and necrosis. Our findings could open up a path to a miRNA based therapeutic approach for treatment of acute megakaryoblastic leukemia.

Molecular Dynamics Studies on D835N Mutation in FLT3-Its Impact on FLT3 Protein Structure

Mutations in Fetal Liver Tyrosine Kinase 3 (FLT3) genes are implicated in the constitutive activation and development of Acute Myeloid Leukaemia (AML). They are involved in signalling pathway of autonomous proliferation and block differentiation in leukaemia cells. FLT3 is considered as a promising target for the therapeutic intervention of AML. There are a few missense mutations associated with FLT3 that are found in AML patients. The D835N mutation is the most frequently observed and the aspartic acid in this position acts as a key residue for the receptor activation. The present study aims to understand the structural effect of D835N mutation in FLT3. We carried out the molecular dynamics (MD) simulation for a period of 120 ns at 300 K. Root-mean square deviation, root-mean square fluctuations, surface accessibility, radius of gyration, hydrogen bond, eigenvector projection analysis, trace of covariance matrix, and density analysis revealed the instability of mutant (D835N) protein. Our study provides new insights on the conformational changes in the mutant (D835N) structure of FLT3 protein. Our observations will be useful for researchers exploring AML and for the development of FLT3 inhibitors.

BH3 mimetic ABT-737 induces apoptosis in CD34+ acute myeloid leukemia cells and shows synergistic effect with conventional chemotherapeutic drugs

AIMS

Acute myeloid leukemia (AML) is an immunophenotypically heterogenous malignant disease. The early immature CD34⁺ AML cell subpopulation is frequently impervious to intensive chemotherapy, making them largely responsible for relapse of AML. CD34⁺ AML cells have higher level of Bcl-2 protein expression than the CD34^- subpopulation. As such, development of drugs that specifically target the Bcl-2 may have the potential to eliminate immature CD34⁺ AML progenitor cells and provide therapeutic benefit. In this work, we made an attempt to investigate the cytotoxic effect of a novel Bcl-2 family inhibitor, ABT-737, on CD34⁺ AML cell lines (KG1a and Kasumi-1) as well as CD34⁺ primary AML cells.

METHODS

Primary human CD34⁺ cells were isolated from bone marrow mononuclear cells using CD34 MicroBead kit. The growth inhibitory effect was measured by cell counting kit-8. Apoptosis was analyzed by annexin V/PI assays. Protein expression was determined by Western blotting analysis.

RESULTS

Inhibition of Bcl-2 by ABT-737 effectively inhibited growth and induced apoptosis in CD34⁺ AML cell lines and CD34⁺ primary AML cells without affecting CD34⁺ normal hematopoietic cells. Furthermore, Western blot analysis showed that ABT-737 induced apoptosis associated with caspase-3 activation and poly ADP-ribose polymerase (PARP) degradation. Finally, ABT-737 synergistically enhanced the cytotoxic effect of cytarabine and daunorubicin in CD34⁺ AML cells.

CONCLUSION

Taken together, these findings indicate that ABT-737 may offer as a promising molecular targeting agent in CD34⁺ AML.

miR-181a modulates acute myeloid leukemia susceptibility to natural killer cells

Although daunorubicin (DNR) is the most widely used anthracycline to treat acute myeloid leukemia (AML), resistance to this drug remains a critical problem. The aim of this study was to investigate the relationship between AML resistance to daunorubicin and susceptibility to natural killer (NK) cell-mediated cell lysis, and the putative expression of miRs. For this purpose, we used the parental AML cell lines U-937 and KG-1 and their equivalent resistant U937(R) and KG-1(R) cell lines. We demonstrate for the first time that the acquisition of resistance to DNR by the parental cell lines resulted in the acquisition of cross-resistance to NK cell-mediated cytotoxicity. miR microarray analysis revealed that this cross-resistance was associated with miR-181a downregulation and the subsequent regulation of MAP3K10 and MAP2K1 tyrosine kinases and the BCL^-2 (BCL^-2 and MCL^-1) family. Overexpression of miR-181a in AML blasts resulted in the attenuation of their resistance to DNR and to NK-cell-mediated killing. These data point to a determinant role of miR-181a in the sensitization of leukemic resistant cells to DNR and NK cells and suggest that miR-181a may provide a promising option for the treatment of immuno- and chemo-resistant blasts.

STAT3 contributes to NK cell recognition by modulating expression of NKG2D ligands in adriamycin-resistant K562/AO2 cells

Leukemic cells can survive after chemotherapy by acquisition of multidrug resistance genes, but other phenotypes related to escape from immune recognition remain elusive. Adriamycin-resistant K562/AO2 cells are less susceptible to elimination by NK cells compared with wild type K562 cells due to lower expression of NKG2D ligands. Treatment of K562/AO2 cells with STAT3 inhibitor VII resulted in reduced expression of multidrug resistance gene P-glycoprotein, and up-regulation of NKG2D ligands on K562/AO2 cells. Meanwhile, K562/AO2 cells treated with STAT3 inhibitor proliferated less and were more susceptible to killing by NK cells than untreated K562/AO2 cells. The enhanced cytotoxicity of NK cells against K562/AO2 cells was partly blocked by treatment of NK cells with anti-NKG2D antibodies. These data suggest that STAT3 contributes to NK cell recognition by modulating NKG2D ligands in K562/AO2 cells, which may a mechanism by which cells survive and cause relapse of leukemia.

Targeting Mitochondria with Avocatin B Induces Selective Leukemia Cell Death

Treatment regimens for acute myeloid leukemia (AML) continue to offer weak clinical outcomes. Through a high-throughput cell-based screen, we identified avocatin B, a lipid derived from avocado fruit, as a novel compound with cytotoxic activity in AML. Avocatin B reduced human primary AML cell viability without effect on normal peripheral blood stem cells. Functional stem cell assays demonstrated selectivity toward AML progenitor and stem cells without effects on normal hematopoietic stem cells. Mechanistic investigations indicated that cytotoxicity relied on mitochondrial localization, as cells lacking functional mitochondria or CPT1, the enzyme that facilitates mitochondria lipid transport, were insensitive to avocatin B. Furthermore, avocatin B inhibited fatty acid oxidation and decreased NADPH levels, resulting in ROS-dependent leukemia cell death characterized by the release of mitochondrial proteins, apoptosis-inducing factor, and cytochrome c. This study reveals a novel strategy for selective leukemia cell eradication based on a specific difference in mitochondrial function.

The molecular signature of AML mesenchymal stromal cells reveals candidate genes related to the leukemogenic process

Acute myeloid leukemia (AML) is a heterogeneous disease characterized by myeloid precursor proliferation in the bone marrow, apoptosis reduction and differentiation arrest. Although there are several studies in this field, events related to disease initiation and progression remain unknown. The malignant transformation of hematopoietic stem cells (HSC) is thought to generate leukemic stem cells, and this transformation could be related to changes in mesenchymal stromal cell (hMSC) signaling. Thus, the aim of this work was to analyze the gene expression profile of hMSC from AML patients (hMSC-AML) compared to healthy donors hMSCs (hMSC-HD). The results showed a common molecular signature for all hMSC-AML. Other assays were performed with a large number of patients and the results confirmed a molecular signature that is capable of distinguishing hMSC-AML from hMSC-HD. Moreover, CCL2 and BMP4 genes encode secreted proteins that could affect HSCs. To verify whether these proteins are differentially expressed in AML patients, ELISA was performed with plasma samples. CCL2 and BMP4 proteins are differentially expressed in AML patients, indicating changes in hMSC-AML signaling. Altogether, hMSCs-AML signaling alterations could be an important factor in the leukemic transformation process.

Tetraspanin 3 Is Required for the Development and Propagation of Acute Myelogenous Leukemia

Acute Myelogenous Leukemia (AML) is an aggressive cancer that strikes both adults and children and is frequently resistant to therapy. Thus, identifying signals needed for AML propagation is a critical step toward developing new approaches for treating this disease. Here, we show that Tetraspanin 3 is a target of the RNA binding protein Musashi 2, which plays a key role in AML. We generated Tspan3 knockout mice that were born without overt defects. However, Tspan3 deletion impaired leukemia stem cell self-renewal and disease propagation and markedly improved survival in mouse models of AML. Additionally, Tspan3 inhibition blocked growth of AML patient samples, suggesting that Tspan3 is also important in human disease. As part of the mechanism, we show that Tspan3 deficiency disabled responses to CXCL12/SDF-1 and led to defects in AML localization within the niche. These identify Tspan3 as an important regulator of aggressive leukemias and highlight a role for Tspan3 in oncogenesis.

herg1b expression as a potential specific marker in pediatric acute myeloid leukemia patients with HERG 897K/K genotype

Human ether-a-go-go related gene (herg) encoding HERG K(+) channel has been demonstrated in many previous studies with its association to cell cycle progression and growth in tumor cells. The upregulated expression of HERG K+ channels was determined in different tumor types. Furthermore, not only full-length transcript herg1 but also a truncated isoform herg1b was shown to be expressed in cancer cells. In this study, the expression levels of herg1 and herg1b and the impact of K897T mutation on their expressions were investigated in pediatric acute myeloid leukemia (pAML). Expression levels of herg1 and herg1b isoforms were analyzed by quantitative real time polymerase chain reaction (PCR) in pAML patients together with healthy donors, and their expressions were confirmed by western blotting. The 2690 A>C nucleotide variation in KCNH2 gene corresponding to K897T amino acid change was analyzed by PCR followed by restriction enzyme digestion. herg1b overexpression was observed in tumor cells compared to healthy controls (P = .0024). However, herg1 expression was higher in healthy control cells than tumor cells (P = .001). The prevalence of polymorphic allele 897T was 26% in our patient group and 897T carriers showed increased herg1b expression compared to wild-type allele carriers. Our results demonstrate the presence of the increased levels of herg1b expression in pAML. In addition, we report for the first time that, pAML subgroup with HERG 897K/K genotype compared to 897K/T and T/T genotypes express increased levels of herg1b. In conclusion, HERG 897K/K genotype with increased level of herg1b expression might well be a prognostic marker for pAML.

Linking the future of anticancer metal-complexes to the therapy of tumour metastases

Cancer chemotherapy is almost always applied to patients with one or more diagnosed metastases and is expected to impact these lesions, thus providing significant benefits to the patient.

Connexin expression in human acute myeloid leukemia cells: identification of patient subsets based on protein and global gene expression profiles

Bone marrow stromal cells support both normal and malignant hematopoiesis. Τhis support is mediated through the local cytokine network and by direct cell‑cell interactions mediated via adhesion molecules and the formation of gap junctions by connexins. Previous studies on connexins in human acute myeloid leukemia (AML) have mainly focused on the investigation of leukemia cell lines. In the present study, we therefore investigated the expression of various connexins at the protein (i.e., cell surface expression) and mRNA level in primary human AML cells. The cell surface expression of the connexins, Cx26, Cx32, Cx37, Cx43 and Cx45, varied considerably between patients, and detectable levels were observed only for subsets of patients. On the whole, Cx43 and Cx45 showed the highest cell surface expression. Connexin expression was dependent on AML cell differentiation, but showed no association with cytogenetic abnormalities or mutations of the fms-related tyrosine kinase 3 (FLT3) or nucleophosmin (NPM)‑1 genes. By contrast, only Cx45 showed a significant variation between patients at the mRNA level. A high Cx45 expression was associated with the altered regulation of the mitogen‑activated protein kinase (MAPK) pathway and the release of pro-inflammatory cytokines [interleukin (IL)‑17, tumor necrosis factor (TNF), interferon‑γ], whereas a low Cx45 expression was associated with the altered regulation of protein functions (i.e., ligase activity, protein folding and catabolism). There was no significant correlation observed between the connexin mRNA and protein levels. Thus, differences in connexin expression can be used to subclassify AML patients. Differences in connexin cell surface expression profiles are not reflected at the mRNA level and have to be directly examined, whereas variations in Cx45 mRNA expression are associated with differences in cell signaling and the regulation of protein functions.

Characteristics and clinical evolution of patients with acute myeloblastic leukemia in northeast Mexico: an eight-year experience at a university hospital

BACKGROUND/OBJECTIVE

Acute myeloid leukemia (AML) is the most common acute leukemia in adults. We documented the characteristics and results of treatment of patients with AML at a single reference center.

METHODS

Patients diagnosed with AML between June 2003 and July 2011 at a university hospital in northeast Mexico were studied. Overall survival (OS) and event-free survival (EFS) were determined, and risk factors were analyzed with respect to their influence on prognosis.

RESULTS

A total of 132 AML patients were included. Median age was 32 years. Complete remission (CR) was achieved by 55% of patients. CR was achieved by 65.1% of patients <60 years (n = 109), compared to 8.7% of those >60 years (n = 23; p < 0.001). In all, 39% of patients >60 years suffered an early death, compared to 14.7% of those <60 years (p < 0.001). OS for patients with AML was 35%, whereas EFS was 32%. On multivariate analysis, patients >60 years had a lower OS and EFS (p < 0.001). A total of 28% of patients received a transplant, and they had high er OS and EFS. Conclusions: Our patients were considerably younger and had remarkably lower survival rates than reported for other populations; those >60 years had a higher early death rate, and fewer of these patients achieved CR.

c-Myc regulates expression of NKG2D ligands ULBP1/2/3 in AML and modulates their susceptibility to NK-mediated lysis

Cytarabine (cytosine arabinoside) is one of the most effective drugs for the treatment of patients diagnosed with acute myeloid leukemia (AML). Despite its efficiency against AML cells, the emergence of drug resistance due to prolonged chemotherapy in most patients is still a major obstacle. Several studies have shown that drug resistance mechanisms alter the sensitivity of leukemia cells to immune system effector cells. To investigate this phenomenon, parental acute myeloid cell lines, HL-60 and KG-1, were continuously exposed to increasing doses of cytarabine in order to establish equivalent resistant cell lines, HL-60(R) and KG-1(R). Our data indicate that cytarabine-resistant cells are more susceptible to natural killer (NK)-mediated cell lysis as compared with parental cytarabine-sensitive cells. The increased susceptibility correlates with the induction of UL-16 binding proteins (ULBP) 1/2/3 and NK group 2, member D (NKG2D) ligands on target cells by a mechanism involving c-Myc induction. More importantly, chromatin immunoprecipitation assay revealed that ULBP1/3 are direct targets of c-Myc. Using drug-resistant primary AML blasts as target cells, inhibition of c-Myc resulted in decreased expression of NKG2D ligands and the subsequent impairment of NK cell lysis. This study provides for the first time, the c-Myc dependent regulation of NKG2D ligands in AML.

The human polynucleotide kinase/phosphatase (hPNKP) inhibitor A12B4C3 radiosensitizes human myeloid leukemia cells to Auger electron-emitting anti-CD123 ¹¹¹In-NLS-7G3 radioimmunoconjugates

INTRODUCTION

Leukemia stem cells (LSCs) are believed to be responsible for initiating and propagating acute myeloid leukemia (AML) and for causing relapse after treatment. Radioimmunotherapy (RIT) targeting these cells may improve the treatment of AML, but is limited by the low density of target epitopes. Our objective was to study a human polynucleotide kinase/phosphatase (hPNKP) inhibitor that interferes with DNA repair as a radiosensitizer for the Auger electron RIT agent, ¹¹¹In-NLS-7G3, which recognizes the CD123⁺/CD131⁻ phenotype uniquely displayed by LSCs.

METHODS

The surviving fraction (SF) of CD123⁺/CD131⁻ AML-5 cells exposed to ¹¹¹In-NLS-7G3 (33-266 nmols/L; 0.74MBq/μg) or to γ-radiation (0.25-5Gy) was determined by clonogenic assays. The effect of A12B4C3 (25 μmols/L) combined with ¹¹¹In-NLS-7G3 (16-66 nmols/L) or with γ-radiation (0.25-2Gy) on the SF of AML-5 cells was assessed. The density of DNA double-strand breaks (DSBs) in the nucleus was measured using the γ-H2AX assay. Cellular dosimetry was estimated based on the subcellular distribution of ¹¹¹In-NLS-7G3 measured by cell fractionation.

RESULTS

Binding of (111)In-NLS-7G3 to AML-5 cells was reduced by 2.2-fold in the presence of an excess (1μM) of unlabeled NLS-7G3, demonstrating specific binding to the CD123⁺/CD131⁻ epitope. ¹¹¹In-NLS-7G3 reduced the SF of AML-5 cells from 86.1 ± 11.0% at 33 nmols/L to 10.5 ± 3.6% at 266 nmols/L. Unlabeled NLS-7G3 had no significant effect on the SF. Treatment of AML-5 cells with γ-radiation reduced the SF from 98.9 ± 14.9% at 0.25Gy to 0.03 ± 0.1% at 5 Gy. A12B4C3 combined with ¹¹¹In-NLS-7G3 (16-66 nmols/L) enhanced the cytotoxicity up to 1.7-fold compared to treatment with radioimmunoconjugates alone and was associated with a 1.6-fold increase in DNA DSBs in the nucleus. A12B4C3 enhanced the cytotoxicity of γ-radiation (0.25-0.5Gy) on AML-5 cells by up to 1.5-fold, and DNA DSBs were increased by 1.7-fold. Exposure to ¹¹¹In-NLS-7G3 (66 nmols/L) delivered up to 0.6Gy to AML-5 cells.

CONCLUSIONS

We conclude that A12B4C3 radiosensitized AML cells to the DNA damaging effects of ¹¹¹In-NLS-7G3. Combination treatment may increase the effectiveness for Auger electron RIT of AML targeting the LSC subpopulation.

Benznidazole modulates cell proliferation in acute leukemia cells

CONTEXT

We have previously reported that benznidazole (BZL), known for its trypanocidal action, has anti-proliferative activity against different cell lines like HeLa and Raw 264.7 among others. At the moment, it has not been reported if the anti-proliferative effect of BZL is similar for non-adherent hematopoietic cells like was reported for adherent cancer cell lines.

OBJECTIVE

We aimed to investigate the efficacy of BZL on the growth of the leukemic cell lines THP-1 and OCI/AML3.

MATERIALS AND METHODS

We evaluated cell proliferation by [³H]-thymidine incorporation and MTT reduction as well as cell death by lactate dehydrogenase (LDH) activity. We assessed apoptosis by flow cytometry for detection of annexin V-positive and propidium iodide-negative cells, along with nuclear morphology by diamidino-2-phenolindole (DAPI) staining. Western blot studies were performed to evaluate changes in cell cycle proteins in BZL-treated cells.

RESULTS

BZL significantly reduced proliferation of both cell lines without inducing cell death. Likewise it produced no significant differences in apoptosis between treated cells and controls. In addition, flow cytometry analysis indicated that BZL caused a larger number of THP-1 cells in G0/G1 phase and a smaller number of cells in S phase than controls. This was accompanied with an increase in the expression of the CDK inhibitor p27 and of cyclin D1, with no significant differences in the protein levels of CDK1, CDK2, CDK4, cyclins E, A and B as compared to controls.

CONCLUSION

BZL inhibits the proliferation of leukemic non-adherent cells by controlling cell cycle at G0/G1 cell phase through up-regulation of p27.

Inhibition of microRNA miR-92a induces apoptosis and necrosis in human acute promyelocytic leukemia

BACKGROUND

MicroRNAs (miRNAs) are endogenous non-coding RNAs, 19-25 nucleotides in length, involved in post-transcriptional regulation of gene expression in a considerable majority of mRNAs. Different aspects of cellular activities like cell growth, proliferation, and differentiation are regulated by miRNAs through their regulatory effects on particular RNA species. In many tumors, up- or down-regulation of different miRNAs has been reported. In acute myeloid leukemia, up-regulation of miR-92a has been reported in human in-vitro studies.

MATERIALS AND METHODS

We performed inhibition of miR-92a in an acute promyelocytic leukemia cell line (HL-60), using locked nucleic acid (LNA) Antagomir. At different time points after LNA-anti-miR92a transfection, qRT-Real-Time-polymerase chain reaction (PCR) and Annexin-V/Propidium Iodide staining were performed and the data was analyzed using the Kruskal-Wallis and Mann-Whitney tests.

RESULTS

The assessment of the apoptosis and necrosis indicates that miR-92a inhibition can decrease the viable HL-60 cells and this is at least partially due to induction of apoptosis.

CONCLUSION

These findings suggest the inhibition of miR-92a as a novel approach for treatment of Acute Promyelocytic Leukemia (APL).

Evaluation of the antitumor effects of BPR1J-340, a potent and selective FLT3 inhibitor, alone or in combination with an HDAC inhibitor, vorinostat, in AML cancer

Overexpression or/and activating mutation of FLT3 kinase play a major driving role in the pathogenesis of acute myeloid leukemia (AML). Hence, pharmacologic inhibitors of FLT3 are of therapeutic potential for AML treatment. In this study, BPR1J-340 was identified as a novel potent FLT3 inhibitor by biochemical kinase activity (IC₅₀ approximately 25 nM) and cellular proliferation (GC₅₀ approximately 5 nM) assays. BPR1J-340 inhibited the phosphorylation of FLT3 and STAT5 and triggered apoptosis in FLT3-ITD⁺ AML cells. The pharmacokinetic parameters of BPR1J-340 in rats were determined. BPR1J-340 also demonstrated pronounced tumor growth inhibition and regression in FLT3-ITD⁺ AML murine xenograft models. The combination treatment of the HDAC inhibitor vorinostat (SAHA) with BPR1J-340 synergistically induced apoptosis via Mcl-1 down-regulation in MOLM-13 AML cells, indicating that the combination of selective FLT3 kinase inhibitors and HDAC inhibitors could exhibit clinical benefit in AML therapy. Our results suggest that BPR1J-340 may be further developed in the preclinical and clinical studies as therapeutics in AML treatments.

Neurologic aspects of lymphoma and leukemias

The lymphomas and leukemias are a heterogenous group of hematologic malignancies with protean manifestations. Neurologic sequelae of the diseases have been recognized since the time the conditions were first described in the mid-1800s. Although our understanding of the various presentations of these blood disorders evolved along with our knowledge of malignancies, accurate diagnosis can still be difficult. It is critical for neurologists to have a high index of clinical suspicion to appropriately recognize their heralding features. This review's focus is the relevant clinical neurologic features and diagnostic studies that identify leukemias and lymphomas affecting the nervous system.

Gentle Massage Improves Disease- and Treatment-Related Symptoms in Patients with Acute Myelogenous Leukemia

OBJECTIVE

Cancer treatment is reported to be stressful, and patients diagnosed with hematologic cancers often exhibit higher levels of anxiety and emotional distress than individuals with other malignancies. Management of these symptoms in patients with hematologic cancer presents significant challenges, as many of them are in and out of the hospital while undergoing high dose chemotherapy. Oncology patients use complementary modalities such as therapeutic massage in an attempt to alleviate disease and treatment-related symptoms, including anxiety and emotional distress. In the current study, the feasibility of a novel massage intervention delivered over the continuum of care, as well as assessment of the immediate and cumulative effects of massage, was examined in patients with acute myelogenous leukemia.

METHODS

A mixed-methods, unmasked, prospective, randomized study was conducted with two groups: a usual care alone control group and a massage therapy intervention plus usual care group.

RESULTS

Significant improvements in levels of stress and health-related quality of life were observed in the massage therapy group versus the usual care alone group, after adjusting for anxiety level, including both immediate and cumulative effects of massage.

CONCLUSIONS

While the findings of the current study regarding acceptability, feasibility, and potential efficacy of therapeutic massage as a complementary health-enhancing intervention in patients diagnosed with acute myelogenous leukemia are very promising, the relatively small size of the study sample limits generalizability.

Oncolytic virotherapy and immunogenic cancer cell death: sharpening the sword for improved cancer treatment strategies

Oncolytic viruses are novel immunotherapeutics with increasingly promising outcomes in cancer patient clinical trials. Preclinical and clinical studies have uncovered the importance of virus-induced activation of antitumor immune responses for optimal therapeutic efficacy. Recently, several classes of chemotherapeutics have been shown to cause immunogenic cancer cell death characterized by the release of immunomodulatory molecules that activate antigen-presenting cells and thus trigger the induction of more potent anticancer adaptive immune responses. In preclinical models, several oncolytic viruses induce immunogenic cell death, which is associated with increased cross-priming of tumor-associated antigens. In this review, we discuss the recent advances in immunogenic cancer cell death as induced by chemotherapeutic treatments, including the roles of relevant danger-associated molecular patterns and signaling pathways, and highlighting the significance of the endoplasmic reticulum (ER) stress response. As virtually all viruses modulate both ER stress and cell death responses, we provide perspectives on future research directions that can be explored to optimize oncolytic viruses, alone or in combination with targeted drug therapies, as potent immunogenic cancer cell death-inducing agents. We propose that such optimized virus-drug synergistic strategies will improve the therapeutic outcomes for many currently intractable cancers.

Overexpression of Mcl-1 confers multidrug resistance, whereas topoisomerase IIβ downregulation introduces mitoxantrone-specific drug resistance in acute myeloid leukemia

Drug resistance is a serious challenge in cancer treatment and can be acquired through multiple mechanisms. These molecular changes may introduce varied extents of resistance to different therapies and need to be characterized for optimal therapy choice. A recently discovered small molecule, ethyl-2-amino-6-(3,5-dimethoxyphenyl)-4-(2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate) (CXL017), reveals selective cytotoxicity toward drug-resistant leukemia. A drug-resistant acute myeloid leukemia cell line, HL60/MX2, also failed to acquire resistance to CXL017 upon chronic exposure and regained sensitivity toward standard therapies. In this study, we investigated the mechanisms responsible for HL60/MX2 cells' drug resistance and the molecular basis for its resensitization. Results show that the HL60/MX2 cell line has an elevated level of Mcl-1 protein relative to the parental cell line, HL60, and its resensitized cell line, HL60/MX2/CXL017, whereas it has a reduced level of topoisomerase IIβ. Mcl-1 overexpression in HL60/MX2 cells is mainly regulated through phospho-extracellular signal-regulated protein kinases 1 and 2-mediated Mcl-1 stabilization, whereas the reduction of topoisomerase IIβ in HL60/MX2 cells is controlled through genetic downregulation. Upregulating Mcl-1 introduces multidrug resistance to standard therapies, whereas its downregulation results in significant cell death. Downregulating topoisomerase IIβ confers resistance specifically to mitoxantrone, not to other topoisomerase II inhibitors. Overall, these data suggest that Mcl-1 overexpression is a critical determinant for cross-resistance to standard therapies, whereas topoisomerase IIβ downregulation is specific to mitoxantrone resistance.

Histone deacetylase inhibition in the treatment of acute myeloid leukemia: the effects of valproic acid on leukemic cells, and the clinical and experimental evidence for combining valproic acid with other antileukemic agents

Several new therapeutic strategies are now considered for acute myeloid leukemia (AML) patients unfit for intensive chemotherapy, including modulation of protein lysine acetylation through inhibition of histone deacetylases (HDACs). These enzymes alter the acetylation of several proteins, including histones and transcription factors, as well as several other proteins directly involved in the regulation of cell proliferation, differentiation and apoptosis. Valproic acid (VPA) is a HDAC inhibitor that has been investigated in several clinical AML studies, usually in combination with all-trans retinoic acid (ATRA) for treatment of patients unfit for intensive chemotherapy, for example older patients, and many of these patients have relapsed or primary resistant leukemia. The toxicity of VPA in these patients is low and complete hematological remission lasting for several months has been reported for a few patients (<5% of included patients), but increased peripheral blood platelet counts are seen for 30 to 40% of patients and may last for up to 1 to 2 years. We review the biological effects of VPA on human AML cells, the results from clinical studies of VPA in the treatment of AML and the evidence for combining VPA with new targeted therapy. However, it should be emphasized that VPA has not been investigated in randomized clinical studies. Despite this lack of randomized studies, we conclude that disease-stabilizing treatment including VPA should be considered especially in unfit patients, because the possibility of improving normal blood values has been documented in several studies and the risk of clinically relevant toxicity is minimal.

Antiproliferative activities of lesser galangal (Alpinia officinarum Hance Jam1), turmeric (Curcuma longa L.), and ginger (Zingiber officinale Rosc.) against acute monocytic leukemia

Acute monocytic leukemia (AML M5 or AMoL) is one of the several types of leukemia that are still awaiting cures. The use of chemotherapy for cancer management can be harmful to normal cells in the vicinity of the target leukemia cells. This study assessed the potency of the extracts from lesser galangal, turmeric, and ginger against AML M5 to use the suitable fractions in neutraceuticals. Aqueous and organic solvent extracts from the leaves and rhizomes of lesser galangal and turmeric, and from the rhizomes only of ginger were examined for their antiproliferative activities against THP-1 AMoL cells in vitro. Lesser galangal leaf extracts in organic solvents of methanol, chloroform, and dichloromethane maintained distinctive antiproliferative activities over a 48-h period. The turmeric leaf and rhizome extracts and ginger rhizome extracts in methanol also showed distinctive anticancer activities. The lesser galangal leaf methanol extract was subsequently separated into 13, and then 18 fractions using reversed-phase high-performance liquid chromatography. Fractions 9 and 16, respectively, showed the greatest antiproliferative activities. These results indicate that the use of plant extracts might be a safer approach to finding a lasting cure for AMoL. Further investigations will be required to establish the discriminatory tolerance of normal cells to these extracts, and to identify the compounds in these extracts that possess the antiproliferative activities.