Apoptosis In Leukemia Cell Lines Research Articles

A novel iheyamine A derivative L42 suppresses acute myeloid leukemia via dual regulation of the PI3K/AKT/FOXO3a axis and TNF signaling pathway

Acute myeloid leukemia (AML) is one of the most common hematopoietic malignancies and the development of new drugs is crucial for the treatment of this lethal disease. Iheyamine A is a nonmonoterpenoid azepinoindole alkaloid from the ascidian Polycitorella sp., and its anticancer mechanism has not been investigated in leukemias. Herein, we showed the significant antileukemic activity of L42 in AML cell lines HEL, HL-60 and THP-1. The IC50 values were 0.466±0.099 µM, 0.356±0.023 µM, 0.475±0.084 µM in the HEL, HL-60 and THP-1 cell lines, respectively, which were lower than the IC50 (2.594±0.271 µM) in the normal liver cell line HL-7702. Furthermore, L42 significantly inhibited the growth of peripheral blood mononuclear cells (PBMCs) from an AML patient. In vivo, L42 effectively suppressed leukemia progression in a mouse model induced by Friend murine leukemia virus (F-MuLV). Mechanistically, we showed that L42 induced cell cycle arrest and apoptosis in leukemia cell lines. RNA sequencing analysis of L42-treated THP-1 cells revealed that the differentially expressed genes (DEGs) were enriched in the cell cycle and apoptosis and predominantly enriched in the PI3K/AKT pathway. Accordingly, L42 decreased the expression of the phospho-PI3K (p85), phospho-AKT and phospho-FOXO3a. Docking and CETSA analysis indicated that L42 bound to the PI3K isoform p110α (PIK3CA), which was implicated in the suppression of the PI3K/AKT pathway. L42 was also shown to initiate the TNF signaling-mediated apoptosis. Moreover, L42 exhibited stronger anti-leukemia activity and sensitivity in IDH2-mutant HEL cells than in IDH2-wild-type control. In conclusion, L42 effectively suppresses cell proliferation and triggers apoptosis in AML cell lines in part through inhibition of the PI3K/AKT signaling pathway to restore FOXO3a expression and activation of the TNF signaling pathway. Thus, the iheyamine A derivative L42 represents a novel candidate for AML therapy.

Septin11 and Septin 8 Play Critical and Overlapping Roles Murine Stem Cell Function

Septins are highly conserved GTP binding proteins which regulate a variety of cellular functions including cytokinesis, polarity, cell cycle, vesicle trafficking, and exocytosis and are now considered the fourth component of the cytoskeleton. Septins are implicated in T and B cell lymphomas; and acute myeloid leukemias, where they frequently act as fusion partners with the Mixed-Lineage Leukemia (MLL) gene. Previous data in our laboratory led to the discovery of a small molecular inhibitor, DW0254, which inhibits RAS function and its downstream target RhoGTPase, Rac, including the hematopoietic-specific Rac2 GTPase, also implicated in MLL leukemias. The inhibitor leads to apoptosis of leukemia cell lines. Using biophysical methods, we discovered that DW0254 binds both the RAS chaperone, PDE6D, and Septin11, which is a member of the Septin6 family (Sara CN, et al., Blood Cancer 2022). Although Septins have been reported to be involved in function of the RhoGTPase Cdc42 and hematopoietic stem progenitor cell (HSPC) polarity, the role of Septin11 in hematopoiesis has not been reported. Septin11 is a member of the Septin6 family of proteins which consists of Septin6, 8, 10, 11 and 14 with significant homology between family members. Previous data in yeast has hypothesized functional overlap within each family of Septin proteins. To better understand the functional role of Septin11, we created lentivirus vectors tagged with a GFP reporter that contained shmiRs against Septin11. Culture of Septin11 knockdown (Septin11 KD) murine HSPC in IMDM (10ng/ml IL-3, 25ng/ml of SCF, TPO, Flt-3 and IL-6) resulted in an average of 13-fold decrease in cell counts compared to controls (p=0.02) and a decrease in total clonogenic activity (Figure 1) with defects seen in both myeloid (GM) and erythroid (BFU-E) colonies. Reduced clonogenic numbers were accompanied by a significant increase in early apoptotic cells suggesting that Septin11 is important in regulating apoptosis in HSPC. To determine the potential role of Septin11 in more primitive hematopoietic cells, we utilized competitive repopulation assays. Transduced BoyJ HSPC (GFP+ Septin11 KD and BFP+ control, mixed 1:1) were injected into lethally irradiated C57Bl/6 mice. We observed a reduction in multilineage chimerism in the peripheral blood, bone marrow, spleen and thymus in primary transplant recipients after knockdown of Septin11 (Table 1). To better define function in specific hematopoietic populations of HSPC, we performed knockdown in FACS-sorted purified cells. Engraftment studies demonstrated a significant reduction in bone marrow chimerism in primary transplant recipients after knockdown of Septin11 most clearly in LT-HSC and ST-HSC (Table 1) with no statistically significant change in MPP. Therefore, to better study the hematopoietic stem cell compartment, we performed secondary transplants utilizing the cells obtained from primary competitive repopulation assays. We observed an unexpected recovery in engraftment in secondary transplant recipients that was accompanied by an increase in the mRNA expression of Septin8. Since Septin8 and Septin11 are closely related we hypothesized that induction of Septin8 was subserving key functions of Septin11. To test this hypothesis, we created a lentivirus vector that expressed both a shmiR against Septin11 and the Septin8 cDNA. Concurrent overexpression of Septin8 with Septin11 knockdown HSPC caused a significant increase in the total number of colonies compared to controls (Figure 1). These data indicate an important role of Septin11 in murine hematopoiesis and a potential redundant role for Septin8.

Caracasine, An ent-kaurane Diterpene with Proapoptotic and Pro-differentiator Activity in Human Leukaemia Cell Lines.

Kaurane-type diterpenoids, obtained from various natural sources, have shown many biological activities, including anti-inflammatory and antitumor effects. Caracasine, an ent-kaurane diterpenoid isolated from the flowers of Croton micans, was shown to induce apoptosis in leukaemia cell lines. The present study aimed to ascertain the compound's mechanism of cell death induction using two leukaemia cell lines, Jurkat E6.1 (T cell) and HL-60 (promyeloblast cells). Cell death in Jurkat and HL60 cells were evaluated by flow cytometry for apoptosis with annexin-V/PI, mitochondrial membrane potential disturbance, changes in cell cycle, CD95 expression, caspase activation, Nuclear Factor kappa B inhibition, and differentiation into a neutrophil-like cell (dHL60). Caracasine (10 μM) increased the G0/G1 phase in Jurkat and arrested the cell cycle in the S phase in HL60. Caracasine increased CD95 expression (p<0.01 in Jurkat and p<0.05 in HL60) and caspase-8 activation (p<0.001 in Jurkat and p<0.05 in HL60). Caspase-9 was activated in both cell lines (p<0.001) along with the decline in mitochondrial Δψm (p<0.05 in Jurkat and p<0.001 in HL60). In HL60 cells, the kaurane induced neutrophil differentiation was assessed by CD40 expression and reactive oxygen species production. In Jurkat cells, caracasine inhibited the NF-κB pathway in cells pretreated with PHA to activate the NF-κB pathway, suggesting a possible role in inflammatory diseases. Caracasine induced apoptosis through the intrinsic and extrinsic pathways in both cell lines were evaluated which could be the leading structure for new anti-leukemic and anti-inflammatory drugs.

Loss of DHX15 Function Impairs Hematopoiesis in Vav-Dhx15-KO Mice and Cause DNA Damage-Induced Cell Cycle Arrest and Apoptosis in Leukemia Cell Lines

DHX15, a member of the DEAD-box RNA helicase family, acts as splicing factor in pre-messenger RNA splicing, pre-ribosomal RNA, and RNA metabolism. Our previous studies showed that DHX15 overexpression is associated with poor prognosis in acute myeloid leukemia (AML), and DHX15 regulates cell apoptosis via the NF-kB signaling pathway(Pan et al., 2017). However, its molecular function remains obscure in the blood system. First, with the Cre-loxp knockout system, Dhx15fl/fl male mice were crossed with vav-icre female mice (specifically expressed in blood system), we found that Dhx15fl/fl; vav-icre homozygous knockout mice (vav-Dhx15-KO) are lethal by E17.5-E18.5. Then, to explore the inner difference in blood system, the hematopoietic stem cells (HSC) were analyzed by flow cytometry in fetal liver (FL) (E13.5, E15.5). Compared with Dhx15fl/fl (wild-type, WT) mice, the lineage-negative cells (Lin- cells; Lin+ Cocktail, CD5, CD45R (B220), CD11b, Anti-Gr-1 (Ly-6G/C), 7-4 and Ter-119) significantly increased in vav-Dhx15-KO FL cells (P<0.0001) and the short-term HSC(ST-HSC) proportion compensatively increased in LSK (Lin-c-Kit+Sca1+cells) population (P<0.01), while the proportion of LK(Lin-c-Kit+Sca1-cells) (P<0.0001 in E13.5, P<0.001 in E15.5), LSK(Lin-c-Kit+Sca1+cells)(P<0.1 in E15.5), and multipotent progenitor (MPP) (P<0.0001 in E15.5) all witnessed decrease in the Lin-/LSK population respectively. Meanwhile, vav-Dhx15-KO mice exhibited impaired multi-lineage hematopoiesis especially in erythroid, where the precursors and immature erythrocytes increased, mature erythrocytes decreased (P<0.001 in E13.5). Next, in vivo competitive repopulation assay were performed to further examine any potential cell-intrinsic defect of HSC function caused by Dhx15-inactivation. Thus, 1,000,000 E13.5/E15.5 total FL donor cells (CD45.2, vav-Dhx15-KO or WT) together with 1,000,000 CD45.1 unfractionated BM competitor cells were intra-venous transplanted into lethally irradiated (9Gy) B6.SJL (CD45.1) recipient mice. Recipient mice were sacrificed 8-weeks after transplantation, flow cytometry was conducted to analysis the ratio of CD45.2 in mice, the results showed that vav-Dhx15-KO FL was severely deficient compared to WT FL(0.1±0.04%vs 62.2±2.8% in BM, 0.2±0.05% vs 64.5±6.1% in SP, 0.1±0.05% vs 45.1±5.5% in PB). These results indicate that Dhx15 is crucial in mice blood system, loss of its function may block cell differentiation, leading to the reduction of mature cells. At the same time, to further explore the molecular mechanism of DHX15 in blood system, MOLM-13 and NB4 leukemia cell lines were selected for shRNA-KD (knockdown) experiments due to the lethality of vav-Dhx15-KO mice. We found that Dhx15-KD significantly impaired the proliferation ability of these cell lines in vitro and in vivo, by experiments of survival competition, clone formation, subcutaneous and intra-venous tumorigenesis. Besides, our data demonstrate DHX15-KD-mediated G0/G1 cell cycle arrest and increase in early-late apoptotic cells by Hoechest 33342-EdU cell cycle and DAPI-Annexin V cell apoptosis assays. Mechanistically, we found that UV_RESPONSE signaling pathway which is mainly related to DNA damage was up-regulated by RNAseq and bioinformatics analysis (DHX15-KD cell line vs WT cell line). Correspondingly, the DNA damage indicators γH2AX and 53BP1 were also increased in DHX15-KD cell lines detected by WB and immunofluorescence experiments, suggesting that the deletion of DHX15 could lead to DNA damage-mediated cell cycle arrest and apoptosis in leukemia cell lines. In summary, these results show that DHX15 deficiency leads to DNA damage-induced cell cycle arrest and apoptosis which further impairs the proliferative capacity of leukemia cell lines and lost function of Dhx15 impairs multi-lineage hematopoiesis in mouse embryos, which may lead to its perinatal death.

TPEN selectively eliminates lymphoblastic B cells from bone marrow pediatric acute lymphoblastic leukemia patients.

B-cell acute lymphoblastic leukemia (B-ALL) is a hematologic disorder characterized by the abnormal proliferation and accumulation of immature B-lymphoblasts arrested at various stages of differentiation. Despite advances in treatment, a significant percentage of pediatric patients with precursor B-ALL still relapse. Therefore, alternative therapies are needed to improve the cure rates for pediatric patients. TPEN (N, N, N', N'-tetrakis(2-pyridylmethyl)-ethylenediamine) is a pro-oxidant agent capable of selectively inducing apoptosis in leukemia cell lines. Consequently, it has been suggested that TPEN could be a potential agent for oxidative therapy. However, it is not yet known whether TPEN can selectively destroy leukemia cells in a more disease-like model, for example, the bloodstream and bone marrow (BM), ex vivo. This investigation is an extension of a previous study that dealt with the effect of TPEN on ex vivo isolated/purified refractory B-ALL cells. Here, we evaluated the effect of TPEN on whole BM from nonleukemic patients (control) or pediatric patients diagnosed with de novo B-ALL or refractory B-ALL cells by analyzing the hematopoietic cell lineage marker CD34/CD19. Although TPEN was innocuous to nonleukemic BM (n = 3), we found that TPEN significantly induced apoptosis in de novo (n = 5) and refractory B-ALL (n = 6) leukemic cell populations. Moreover, TPEN significantly increased the counts of cells positive for the oxidation of the stress sensor protein DJ-1, a sign of the formation of H2O2, and significantly increased the counts of cells positive for the pro-apoptotic proteins TP53, PUMA, and CASPASE-3 (CASP-3), indicative of apoptosis, in B-ALL cells. We demonstrate that TPEN selectively eliminates B-ALL cells (CD34 + /CD19 +) but no other cell populations in BM (CD34 + /CD19-; CD34-/CD19 + ; CD34-/CD19-) independent of age, diagnosis status (de novo or refractory), sex, karyotype, or immunophenotype. Understanding TPEN-induced cell death in leukemia cells provides insight into more effective therapeutic oxidation-inducing anticancer agents.

Dysregulation of LINC00324 associated with methylation facilitates leukemogenesis in de novo acute myeloid leukemia.

LINC00324 was overexpressed and facilitated carcinogenesis in various solid malignant tumors. However, the role of LINC00324 in leukemogenesis remains to be elucidated. The relative expression and unmethylation levels of LINC00324 were detected by real-time quantitative PCR (RT-qPCR) and real-time quantitative methylation-specific PCR (RT-qMSP). Cell proliferation experimental and flow cytometer (FCM) was used to detect the change of proliferation and apoptosis in leukemia cell lines after overexpression of LINC00324. The results showed that the expression of LINC00324 and the methylation level of the promoter region were significantly negatively correlated in AML patients. Moreover, patients with lower LINC00324 expression showed more prolonged overall survival (OS). Remarkably, overexpression of LINC00324 in leukemia cell lines promoted the proliferation of target cells and inhibited their apoptosis. Our findings firstly identified that the hypomethylation of LINC00324 was a common molecular event in de novo AML patients. The abnormally upregulated LINC00324 promotes proliferation and inhibits apoptosis in leukemia cells.

The G-Protein-Coupled Estrogen Receptor Agonist G-1 Inhibits Proliferation and Causes Apoptosis in Leukemia Cell Lines of T Lineage.

The G-protein–coupled estrogen receptor (GPER) mediates non-genomic action of estrogen. Due to its differential expression in some tumors as compared to the original healthy tissues, the GPER has been proposed as a therapeutic target. Accordingly, the non-steroidal GPER agonist G-1, which has often demonstrated marked cytotoxicity in experimental models, has been suggested as a novel anticancer agent for several sensitive tumors. We recently revealed that cell lines derived from acute T-cell (query) lymphoblastic leukemia (T-ALL) express the GPER. Here, we address the question whether G-1 is cytotoxic to T-ALL. We have shown that G-1 causes an early rise of intracellular Ca2+, arrests the cell cycle in G2/M, reduces viability, and provokes apoptosis in T-ALL cell lines. Importantly, G-1 caused destabilization and depolymerization of microtubules. We assume that it is a disturbance of the cytoskeleton that causes G-1 cytotoxic and cytostatic effects in our model. The observed cytotoxic effects, apparently, were not triggered by the interaction of G-1 with the GPER as pre-incubation with the highly selective GPER antagonist G-36 was ineffective in preventing the cytotoxicity of G-1. However, G-36 prevented the intracellular Ca2+ rise provoked by G-1. Finally, G-1 showed only a moderate negative effect on the activation of non-leukemic CD4+ lymphocytes. We suggest G-1 as a potential antileukemic drug.

Urolithin A and B Alter Cellular Metabolism and Induce Metabolites Associated with Apoptosis in Leukemic Cells.

Leukemia is persistently a significant cause of illness and mortality worldwide. Urolithins, metabolites of ellagic acid and ellagitannins produced by gut microbiota, showed better bioactive compounds liable for the health benefits exerted by ellagic acid and ellagitannins containing pomegranate and walnuts. Here, we assessed the potential antileukemic activities of both urolithin A and urolithin B. Results showed that both urolithin A and B significantly inhibited the proliferation of leukemic cell lines Jurkat and K562, among which urolithin A showed the more prominent antiproliferative capability. Further, urolithin treatment alters leukemic cell metabolism, as evidenced by increased metabolic rate and notable changes in glutamine metabolism, one-carbon metabolism, and lipid metabolism. Next, we evidenced that both urolithins equally promoted apoptosis in leukemic cell lines. Based on these observations, we concluded that both urolithin A and B alter leukemic cell metabolome, resulting in a halt of proliferation, followed by apoptosis. The data can be used for designing new combinational therapies to eradicate leukemic cells.

Essential oil extracted from plant tuber of nutgrass “Cyperus rotundus” effectively decreased sperm quality of mice

Tuber extract of nutgrass (Cyperus rotundus or rumput teki), induce apoptosis in leukemia cell lines. This effect related to the essential oil content of nutgrass. The present study aim ed to evaluate the effect of nutgrass essential oil on the quality of sperm in mice. Mice were divided into 4 groups using a completely randomized design. Group 1 (control) received only distilled water. Groups 2, 3, and 4 received 9, 18 and 36 mg/ 30gBW essential oil, respectively for 35 days. At the end of 35 d

The rRNA synthesis inhibitor CX-5461 may induce autophagy that inhibits anticancer drug-induced cell damage to leukemia cells.

Autophagy induced in cancer cells during chemotherapy is classified into two types, which differ depending on the kind of cells or anticancer drugs. The first type of autophagy contributes to the death of cells treated with drugs. In contrast, the second type plays a crucial role in preventing anticancer drug-induced cell damages; the use of an autophagy inhibitor is considered effective in improving the efficacy of chemotherapy. Thus, it is important to determine which type of autophagy is induced during chemotherapy. Here, we showed that a novel inhibitor of RNA polymerase I, suppresses growth, induces cell cycle arrest and promotes apoptosis in leukemia cell lines. The number of apoptotic cells induced by co-treatment with CX-5461 and chloroquine, an autophagy inhibitor, increased compared with CX-5461 alone. Thus, the autophagy which may be induced by CX-5461 was the second type.

Effect of SOCS1 Gene on Growth Inhibition of Acute Myeloid Leukemia Cells Mediated by JAK2/STAT Signaling Pathway

To explore the correlation of SOCS1 gene methylation with the activity of JAK2/STAT signaling pathway, genesis and progress of acute myeloid leukemia. Several techniques, such as cell culture, qPCR, MS-PCR, Western bolt, CCK-8 assay, flow cytometry and gene transfection were used to analyze the relation of expression and methylation statues of SOCS1 gene with the genesis and progression of AML in 120 AML patients and leukemia cell lines U937 and THP-1, at the same time to analyze the changes of downstream protein expression in JAK2/STAT signaling pathway and their effect on the growth and apoptosis of leukemia cell lines. The positive rate of WT1/ABL in SOCS1 methylated group was significantly higher than that in SOCS1 non-methylated group, and the complete remission rate of one course treatment in SOCS1-methylated group was significantly lower than that in SOCS1 non-methylated group. The expression level of SOCS1 gene in low methylation rate group was higher, and the expression of down-stream proteins p-JAK2, p-STAT3 and p-STAT5 in JAK2/STAT signaling pathway decreased, while the expression of t-JAK2,t-STAT3 and t-STAT5 was not changed statistically significantly. The growth rate of leukemia cells graduated decreased, and the apoptosis rate of leukemia cells graduated increased along with the enhancement of methylation drug concentration. The methylation of SOCS1 gene results in the gene silencing, thereby declines its inhibition on the down-stream proteins in JAK2/STAT signaling pathway, and finally promotes the growth and proliferation of AML cells.

Endogenous retroviruses are a source of enhancers with oncogenic potential in acute myeloid leukaemia

Acute myeloid leukemia (AML) is characterised by a series of genetic and epigenetic alterations that result in deregulation of transcriptional networks. One understudied source of transcriptional regulators are transposable elements (TEs), whose aberrant usage could contribute to oncogenic transcriptional circuits. However, the regulatory influence of TEs and their links to AML pathogenesis remain unexplored. Here we identify six endogenous retrovirus (ERV) families with AML-associated enhancer chromatin signatures that are enriched in binding of key regulators of hematopoiesis and AML pathogenesis. Using both locus-specific genetic editing and simultaneous epigenetic silencing of multiple ERVs, we demonstrate that ERV deregulation directly alters the expression of adjacent genes in AML. Strikingly, deletion or epigenetic silencing of an ERV-derived enhancer suppresses cell growth by inducing apoptosis in leukemia cell lines. This work reveals that ERVs are a previously unappreciated source of AML enhancers that may be exploited by cancer cells to help drive tumour heterogeneity and evolution.

Hyperoxia Alters Ultrastructure and Induces Apoptosis in Leukemia Cell Lines

Oxygenation conditions are crucial for growth and tumor progression. Recent data suggests a decrease in cancer cell proliferation occurring after exposure to normobaric hyperoxia. Those changes are associated with fractal dimension. The purpose of this research was to study the impact of hyperoxia on apoptosis and morphology of leukemia cell lines. Two hematopoietic lymphoid cancer cell lines (a T-lymphoblastoid line, JURKAT and a B lymphoid line, CCRF-SB) were tested under conditions of normobaric hyperoxia (FiO2 > 60%, ± 18h) and compared to a standard group (FiO2 = 21%). We tested for apoptosis using a caspase-3 assay. Cell morphology was evaluated by cytospin, microphotography after coloration, and analysis by a fractal dimension calculation software. Our results showed that exposure of cell cultures to transient normobaric hyperoxia induced apoptosis (elevated caspase-3) as well as significant and precocious modifications in cell complexity, as highlighted by increased fractal dimensions in both cell lines. These features are associated with changes in structure (pycnotic nucleus and apoptosis) recorded by microscopic analysis. Such morphological alterations could be due to several molecular mechanisms and rearrangements in the cancer cell, leading to cell cycle inhibition and apoptosis as shown by caspase-3 activity. T cells seem less resistant to hyperoxia than B cells.

Melittin-A Natural Peptide from Bee Venom Which Induces Apoptosis in Human Leukaemia Cells.

Bee venom is a very complex mixture produced and secreted by the honeybee (Apis mellifera). Melittin is a major component of bee venom that accounts for about 52% of its dry mass. A vast number of studies have been dedicated to the effects of melittin’s regulation of apoptosis and to the factors that induce apoptosis in various types of cancer such as breast, ovarian, prostate, lung. The latest evidence indicates its potential as a therapeutic agent in the treatment of leukaemia. The aim of our present study is to evaluate melittin’s ability to induce apoptosis in leukaemia cell lines of different origin acute lymphoblastic leukaemia (CCRF-CEM) and chronic myelogenous leukaemia (K-562). We demonstrated that melittin strongly reduced cell viability in both leukaemia cell lines but not in physiological peripheral blood mononuclear cells (PMBCs). Subsequent estimated parameters (mitochondrial membrane potential, Annexin V binding and Caspases 3/7 activity) clearly demonstrated that melittin induced apoptosis in leukaemia cells. This is a very important step for research into the development of new potential anti-leukaemia as well as anticancer therapies. Further analyses on the molecular level have been also planned (analysis of proapoptotic genes expression and DNA damages) for our next research project, which will also focus on melittin.

Clinical and preclinical characterization of CD99 isoforms in acute myeloid leukemia.

In an effort to identify target genes in acute myeloid leukemia (AML), we compared gene expression profiles between normal and AML cells from various publicly available datasets. We identified CD99, a gene that is up-regulated in AML patients. In 186 patients from The Cancer Genome Atlas AML dataset, CD99 was over-expressed in patients with FLT3-ITD and was down-regulated in patients with TP53 mutations. CD99 is a trans-membrane protein expressed on leukocytes and plays a role in cell adhesion, trans-endothelial migration, and T-cell differentiation. The CD99 gene encodes two isoforms with distinct expression and functional profiles in both normal and malignant tissues. Here we report that, although the CD99 long isoform initially induces an increase in cell proliferation, it also induces higher levels of reactive oxygen species, DNA damage, apoptosis and a subsequent decrease in cell viability. In several leukemia murine models, the CD99 long isoform delayed disease progression and resulted in lower leukemia engraftment in the bone marrow. Furthermore, the CD99 monoclonal antibody reduced cell viability, colony formation, and cell migration, and induced cell differentiation and apoptosis in leukemia cell lines and primary blasts. Mechanistically, CD99 long isoform resulted in transient induction followed by a dramatic decrease in both ERK and SRC phosphorylation. Altogether, our study provides new insights into the role of CD99 isoforms in AML that could potentially be relevant for the preclinical development of CD99 targeted therapy.

INTEGRATIVE EPIGENOMIC ANALYSIS TO IDENTIFY POTENTIAL BIOMARKERS IN KMT2A TRANSLOCATED ACUTE MYELOID LEUKEMIA

Introduction Acute leukemia is characterized by abnormalities affecting the self-renewal of hematopoietic stem cells and differentiation of myeloid or lymphoid lineages. Our lab is focused on developing a better understanding of the biology of acute leukemias involving the KMT2A-MLLT3 fusion that is commonly found in pediatric leukemias. Methods/Results By transducing healthy CD34+ cord blood cells with the KMT2A-MLLT3 fusion and xenografting them into immunodeficient mice, we can generate human acute leukemias where the genetic background of the initial donor is defined. We have used this model system to interrogate the epigenetic changes that occur at the earliest stages of leukemogenesis, something which is not possible with patient samples. Interestingly, two distinctive DNA methylation patterns were observed in model myeloid and lymphoid samples, although acute leukemias can arise from the same molecular events. Furthermore, our ChIP-seq and ATAC-seq data revealed that the KMT2A-MLLT3 induction has a significant impact on chromatin rearrangement and distribution of histone marks. By correlating these epigenetic data with gene expression data from patient and model leukemic cells, we identified novel potential biomarkers that are specifically highly expressed and epigenetically regulated in KMT2A-rearranged leukemias. The pharmacological inhibition of one of these genes, encoding a GPCR, leads to significant apoptosis in leukemic cell lines highlighting its essential role in leukemogenesis. Conclusion An epigenetic reprogramming is required for KMT2A-MLLT3 acute leukemia development. This study also highlights novel biomarkers that are not only of potential clinical interest, but also likely reflect important aspects of the underlying biology of KMT2A-translocated leukemias.

Influence of LBP alone or Combined with TRAIL on Apoptosis of MLL Rearranged Leukemic Cells

To investigate the effect of lycium barbarum polysaccharide (LBP) alone or combined with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) on the apoptosis of leukemia cell lines with MLL gene-rearrangement, and to explore the cell apoptotic pathway after the combined action. MLL-ALL cell line KOCL44 and KOCL45 were selected as the research object, then the control and experimental groups were set up. The cell survival rate was measured by the trypan blue dye exclusion method, the cell early apoptosis and expression of death receptors on the cell surface were detected by flow cytometry with Annexin-V/PI double staining. The protein level of caspase-8, BID, caspase-3, caspase-9, BAD, BCL-2, as well as mitochondrial and cytosol Cyto-C were detected by Western blot. LBF combined with TRAIL inhibited the growth of KOCL44 and KOCL-45 cells and showed the synergistic effect, the results of flow cytometry with Amnexiu V/PI double staining were consistent with above-mentioned results. After treatment of KOCL44 and KOCL45 cells with LBF plus TRAIL, the significant expression of DR4 on cell surface was not found, while the expression of DR4 receptor was enhanced significantly, the pro-apoptotic proteins including caspase-8, BID, caspase-3, caspase-9 and BAD were activated significantly and BCL-2 was suppressed significantly with time-dependent manner. The expression of mitochondria cyto-C in KOCL44 and KOCL45 decreased along with prolonging of treatment time (r=-0.95, r=-0.866), while the expression of cytosol cyto-C in KOCL44 and KOCL45 increased along with prolonging of treatment time (r=0.883, r=0.903). The combination of LBP and TRAIL significantly increases the apoptosis of KOCL44 and KOCL45, and the LBP and TRAIL can up-regulate the expression of TRAIL death receptor-DR5 on the cell surface, activate the pathway of caspase and mito-chrondia mitachondria, thus enhance the sensitivity of KOCL44 and KOCL45 to TRAIL induced apoptosis through both mitochondrial and apoptotic pathway.

The Effect of Furanocoumarin Derivatives on Induction of Apoptosis and Multidrug Resistance in Human Leukemic Cells.

Background: The insensitivity of cancer cells to therapeutic agents is considered to be the main cause of failure of therapy and mortality of patients with cancer. A particularly important problem in these patients is the phenomenon of multidrug resistance, consisting of abnormal, elevated expression of transport proteins (ABC family). The aim of this research included determination of IC50 values of selected furanocoumarins in the presence and absence of mitoxantrone in leukemia cells and analysis of changes in apoptosis using anexinV/IP and Casp3/IP after 24 h exposure of cell lines to selected coumarins in the presence and absence of mitoxantrone in IC50 concentrations. Methods: Research was conducted on 3 cell lines derived from the human hematopoietic system: HL-60, HL-60/MX1 and HL-60/MX2. After exposure to coumarin compounds, cells were subjected to cytometric analysis to determine the induction of apoptosis by two methods: the Annexin V test with propidium iodide and the PhiPhiLux-G1D2 reagent containing caspase 3 antibodies. Results: All of the furanocoumarin derivatives studied were found to induce apoptosis in leukemia cell lines. Conclusions: Our results clearly show that the furanocoumarin derivatives are therapeutic substances with antitumor activity inducing apoptosis in human leukemia cells with phenotypes of resistance.

Greensporone A, a Fungal Secondary Metabolite Suppressed Constitutively Activated AKT via ROS Generation and Induced Apoptosis in Leukemic Cell Lines.

Greensporone A is a fungal secondary metabolite that has exhibited potential in vitro for anti-proliferative activity in vitro. We studied the anticancer activity of greensporone A in a panel of leukemic cell lines. Greensporone A-mediated inhibition of proliferation is found to be associated with the induction of apoptotic cell death. Greensporone A treatment of leukemic cells causes inactivation of constitutively activated AKT and its downstream targets, including members GSK3 and FOXO1, and causes downregulation of antiapoptotic genes such as Inhibitor of Apoptosis (IAPs) and Bcl-2. Furthermore, Bax, a proapoptotic member of the Bcl-2 family, was found to be upregulated in leukemic cell lines treated with greensporone A. Interestingly, gene silencing of AKT using AKT specific siRNA suppressed the expression of Bcl-2 with enhanced expression of Bax. Greensporone A-mediated increase in Bax/Bcl-2 ratio causes permeabilization of the mitochondrial membrane leading to the accumulation of cytochrome c in the cytoplasm. Greensporone A-induced cytochrome c accumulation causes the activation of caspase cascade and cleavage of its effector, poly(ADP-ribose) polymerase (PARP), leading to apoptosis. Greensporone A-mediated apoptosis in leukemic cells occurs through the generation of reactive oxygen species (ROS) due to depletion of glutathione (GSH) levels. Finally, greensporone A potentiated the anticancer activity of imatinib in leukemic cells. In summary, our study showed that greensporone A suppressed the growth of leukemic cells via induction of apoptotic cell death. The apoptotic cell death occurs by inhibition of AKT signaling and activation of the intrinsic apoptotic/caspase pathways. These results raise the possibility that greensporone A could be developed as a therapeutic agent for the treatment of leukemia and other hematological malignancies.

Antisense STAT3 inhibitor decreases viability of myelodysplastic and leukemic stem cells.

Acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) are associated with disease-initiating stem cells that are not eliminated by conventional therapies. Transcriptomic analysis of stem and progenitor populations in MDS and AML demonstrated overexpression of STAT3 that was validated in an independent cohort. STAT3 overexpression was predictive of a shorter survival and worse clinical features in a large MDS cohort. High STAT3 expression signature in MDS CD34+ cells was similar to known preleukemic gene signatures. Functionally, STAT3 inhibition by a clinical, antisense oligonucleotide, AZD9150, led to reduced viability and increased apoptosis in leukemic cell lines. AZD9150 was rapidly incorporated by primary MDS/AML stem and progenitor cells and led to increased hematopoietic differentiation. STAT3 knockdown also impaired leukemic growth in vivo and led to decreased expression of MCL1 and other oncogenic genes in malignant cells. These studies demonstrate that STAT3 is an adverse prognostic factor in MDS/AML and provide a preclinical rationale for studies using AZD9150 in these diseases.