OBJECTIVETo investigate the role of Rheb (mTOR activator) in AML development by measuring Rheb expression in bone marrow of adult AML patients and in AML cell line HL-60.

METHODSReal-time PCR assay was used to measure the Rheb mRNA expression in 27 AML patients and 29 ITP patients as control. The relationship between Rheb mRNA expression and age, AML subtype, fusion gene, splenomegaly, hepatomegaly and survival of AML patients was analyzed and compared. In addition, HL-60 cell line over-expressing Rheb was established, and the HL-60 cells and HL-60 cells with overexpression of Rheb were treated with Ara-C of different concentrations, the proliferation level was detected by CCK-8 method, and the IC50 was calculated.

RESULTSThe mRNA level of Rheb in AML patients was similar to that in ITP patients (control). Interestingly, higher expression of Rheb was associated with better survival and was sensitive to Ara-C treatment. However, the expression level of Rheb was not associated with age, AML subtype, fusion gene, and hepatomegaly of patients. Lower expression level of Rheb was associated with splenomegaly. In vitro analysis of HL-60 line indicated that overexpression of Rheb could increased the cell sensitivity to Ara-C treatment (IC50=0.54 µmol/L) and caused HL-60 cell apoptosis.

CONCLUSIONThe lower Rheb expression is a poor prognostic indicator for AML patients, which is associated with AML splenomegaly, the patients and HL-60 cells with low expression of Rheb are insensitive to Ara-C treatment.

Adult ; Apoptosis ; Bone Marrow ; metabolism ; Cytarabine ; pharmacology ; HL-60 Cells ; Humans ; Leukemia, Myeloid, Acute ; genetics ; metabolism ; pathology ; Monomeric GTP-Binding Proteins ; genetics ; metabolism ; Neuropeptides ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Ras Homolog Enriched in Brain Protein ; Real-Time Polymerase Chain Reaction ; Spleen ; pathology

OBJECTIVETo investigate miR-181a function and regulation mechanism by identifying miR-181a target genes in acute myeloid leukemia (AML).

METHODSThe HL-60 cells of human AML was transfected by small molecular analog miR-181a, the cell proliferation was detected by CCK-8 method after electroporation in HL-60 cell lines. Target genes of miR-181a were predicted and analyzed by the bioinformatics software and database. Target genes were confirmed by HL-60 cell line and the patient leukemia cells.

RESULTSOverexpressed miR-181a in HL-60 cell line significantly enhanced cell proliferation compared with that in control (P < 0.05). Dual luciferase reporter gene assay showed that miR-181a significantly suppressed the reporter gene activity containing ATM 3'-UTR by about 56.8% (P < 0.05), but it didn't suppress the reporter gene activity containing 3'-UTR ATM mutation. Western blot showed that miR-181a significantly downregulated the expression of ATM in human leukemia cells. It is also found that miR-181a was significantly increased in AML, which showed a negative correlation with ATM expression.

CONCLUSIONmiR-181a promotes cell proliferation in AML by regulating the tumor suppressor ATM, thus it plays the role as oncogene in pathogenesis of AML.

Ataxia Telangiectasia Mutated Proteins ; metabolism ; Cell Proliferation ; Down-Regulation ; HL-60 Cells ; Humans ; Leukemia, Myeloid, Acute ; metabolism ; pathology ; MicroRNAs ; genetics ; metabolism ; Transfection

OBJECTIVETo explore the effect of decitabine on Dickkopf-1 (DKK1) gene expression level and its downstream Wnt signaling pathway in acute myeloid leukemia (AML) cell line HL-60.

METHODSFlow cytometry and DNA ladder analysis were performed to detect apoptosis in HL-60 cell treated with different concentration of decitabine. Methylation-specific polymerase chain reaction (MS-PCR) was used to examine the methylation status of DKK1 gene. The expressions of mRNA and protein were determined by qRT-PCR and Western blot, respectively.

RESULTSFlow cytometric detection showed that after treating HL-60 cell line with decitabine of different concentrations for 48 h, the early apoptosis of HL-60 cells increased significantly as compared with control group (P < 0.05). DNA ladder analysis showed that the DNA ladder and demethylation of DKK1 gene appeared. RT-PCR and Western blot showed that the expressions of mRNA and protein increased. The protein expressions of β-catenin and C-MYC decreased.

CONCLUSIONThe decitabine can promote the apoptosis of HL-60 cells throngh demethylation of DDK1 gene and inhibition of Wnt signalling pathway.

Apoptosis ; Azacitidine ; analogs & derivatives ; pharmacology ; DNA Methylation ; Gene Expression Regulation, Bacterial ; Genes, myc ; HL-60 Cells ; drug effects ; Humans ; Intercellular Signaling Peptides and Proteins ; metabolism ; Leukemia, Myeloid, Acute ; pathology ; RNA, Messenger ; Wnt Signaling Pathway ; beta Catenin ; metabolism

BACKGROUNDThe acute myeloid leukemia 1 (AML1)-eight-twenty-one (ETO) fusion protein generated by the t(8;21)(q22;q22) translocation is considered to display a crucial role in leukemogenesis in AML. By focusing on the anti-leukemia effects of eyes absent 4 (EYA4) gene on AML cells, we investigated the biologic and molecular mechanism associated with AML1-ETO expressed in t(8;21) AML.

METHODSQualitative polymerase chain reaction (PCR), quantitative reverse transcription PCR (RT-PCR), and Western blotting analysis were used to observe the mRNA and protein expression levels of EYA4 in cell lines. Different plasmids (including mutant plasmids) of dual luciferase reporter vector were built to study the binding status of AML1-ETO to the promoter region of EYA4. Chromatin immunoprecipitation assay was used to study the epigenetic silencing mechanism of EYA4. Bisulfite sequencing was applied to detect the methylation status in EYA4 promoter region. The influence of EYA4 gene in the cell proliferation, apoptosis, and cell clone-forming ability was detected by the technique of Cell Counting Kit-8, flow cytometry, and clonogenic assay.

RESULTSEYA4 gene was hypermethylated in AML1-ETO+ patients and its expression was down-regulated by 6-fold in Kasumi-1 and SKNO-1 cells, compared to HL-60 and SKNO-1-siA/E cells, respectively. We demonstrated that AML1-ETO triggered the epigenetic silencing of EYA4 gene by binding at AML1-binding sites and recruiting histone deacetylase 1 and DNA methyltransferases. Enhanced EYA4 expression levels inhibited cellular proliferation and suppressed cell colony formation in AML1-ETO+ cell lines. We also found EYA4 transfection increased apoptosis of Kasumi-1 and SKNO-1 cells by 1.6-fold and 1.4-fold compared to negative control, respectively.

CONCLUSIONSOur study identified EYA4 gene as targets for AML1-ETO and indicated it as a novel tumor suppressor gene. In addition, we provided evidence that EYA4 gene might be a novel therapeutic target and a potential candidate for treating AML1-ETO+ t (8;21) AML.

Apoptosis ; genetics ; physiology ; Blotting, Western ; Cell Line, Tumor ; Cell Proliferation ; genetics ; physiology ; Chromatin Immunoprecipitation ; Core Binding Factor Alpha 2 Subunit ; genetics ; metabolism ; DNA Methylation ; genetics ; Epigenesis, Genetic ; genetics ; Gene Silencing ; HL-60 Cells ; Humans ; Leukemia, Myeloid, Acute ; genetics ; metabolism ; pathology ; Oncogene Proteins, Fusion ; genetics ; metabolism ; RNA, Small Interfering ; genetics ; RUNX1 Translocation Partner 1 Protein ; Radioimmunoprecipitation Assay ; Trans-Activators ; genetics ; metabolism

OBJECTIVETo investigate the antitumor efficacy and mechanism of HSP90 inhibitor FW-04-806 against Bcr/Abl(+) leukemia K562 and HL60 cells and their mechanisms of action.

METHODSMTT assay was used to assess the proliferation-inhibiting effect of FW-04-806. Cell cycle was analyzed with propidium iodide by flow cytometry. Cell apoptosis was determined using the FITC mV apoptosis detection kit. Western blot was applied to reveal the protein expression of related proliferative and apoptotic signaling pathways. The changes of mitochondrial membrane potential were detected by flow cytometry. Protein-protein interactions was shown by co-immunoprecipitation. The level of mRNA was assessed by real-time RT-PCR.

RESULTSFW-04-806 obviously inhibited cell proliferation in the HL60, K562 and HL60/Bcr-Abl cell lines, with an IC50 of (30.89 ± 0.12) µmol/L, (9.76 ± 0.19) µmol/L and (8.03 ± 0.26) µmol/L, respectively (P<0.001). Compared with the vehicle group, the two increasing doses of FW-04-806 showed inhibition of tumor growth at a rate of (17.40 ± 0.34)% and (34.33 ± 5.00)%, respectively, in the K562 cell line groups (P=0.003), and (18.90 ± 1.45)% and (35.60 ± 3.55)% (P=0.001) in the HL60/Bcr-Abl cell line groups. FW-04-806 dissociated Hsp90/Cdc37 chaperon/co-chaperon complex, followed by degradation of the Hsp90 proteins through proteasome pathway without affecting mRNA expression. FW-04-806 induced apoptosis and led to G2/M arrest.

CONCLUSIONOur findings indicate that FW-04-806 displays potential antitumor effect by suppressing the proliferation and apoptosis in Bcr/Abl(+) leukemia cells in vivo.

Apoptosis ; drug effects ; Cell Cycle ; Cell Proliferation ; drug effects ; Fusion Proteins, bcr-abl ; HL-60 Cells ; HSP90 Heat-Shock Proteins ; antagonists & inhibitors ; Humans ; K562 Cells ; Leukemia ; drug therapy ; metabolism ; pathology ; Membrane Potential, Mitochondrial ; Oxazoles ; pharmacology ; RNA, Messenger ; metabolism ; Signal Transduction

SUV39H1 is a histone 3 lysine 9 (H3K9)-specific methyltransferase that is important for heterochromatin formation and the regulation of gene expression. Chaetocin specifically inhibits SUV39H1, resulted in H3K9 methylation reduction as well as reactivation of silenced genes in cancer cells. Histone deacetylase (HDAC) inhibitors inhibit deacetylases and accumulate high levels of acetylation lead to cell cycle arrest and apoptosis. In this study, we demonstrated that treatment with chaetocin enhanced apoptosis in human leukemia HL60, KG1, Kasumi, K562, and THP1 cells. In addition, chaetocin induced the expression of cyclin-dependent kinase inhibitor 2B (p15), E-cadherin (CDH1) and frizzled family receptor 9 (FZD9) through depletion of SUV39H1 and reduced H3K9 methylation in their promoters. Co-treatment with chaetocin and HDAC inhibitor trichostatin A (TSA) dramatically increased apoptosis and produced greater activation of genes. Furthermore, this combined treatment significantly increased loss of SUV39H1 and reduced histone H3K9 trimethylation responses accompanied by increased acetylation. Importantly, co-treatment with chaetocin and TSA produced potent antileukemic effects in leukemia cells derived from patients. These in vitro findings suggest that combination therapy with SUV39H1 and HDAC inhibitors may be of potential value in the treatment of leukemia.
Acetylation/drug effects ; Adolescent ; Adult ; Aged ; Apoptosis/*drug effects ; Cadherins/metabolism ; Cell Line, Tumor ; Cyclin-Dependent Kinase Inhibitor p15/metabolism ; DNA Methylation/drug effects ; Enzyme Inhibitors/therapeutic use/*toxicity ; Frizzled Receptors/metabolism ; Gene Expression Regulation/drug effects ; HL-60 Cells ; Histone Deacetylase Inhibitors/therapeutic use/*toxicity ; Histone-Lysine N-Methyltransferase/*antagonists & inhibitors/metabolism ; Histones/genetics/metabolism ; Humans ; Hydroxamic Acids/therapeutic use/*toxicity ; K562 Cells ; Leukemia/drug therapy/metabolism/pathology ; Leukemia, Myeloid, Acute/genetics/metabolism/pathology ; Male ; Middle Aged ; Piperazines/therapeutic use/toxicity ; Promoter Regions, Genetic ; Young Adult

The activity of the mTOR pathway is frequently increased in acute myeloid leukemia, and is tightly related with cellular proliferation. Leucine is tightly linked to the mTOR pathway and can activate it, thereby stimulating cellular proliferation. LAT3 is a major transporter for leucine, and suppression of its expression can reduce cell proliferation. Here, we show that suppression of LAT3 expression can reduce proliferation of the acute leukemia cell line, K562. We investigated the mRNA and protein expression of LAT3 in several leukemia cell lines and normal peripheral blood mononuclear cells (PBMNCs) using RT-PCR and Western blotting. We also evaluated cell viability using a methyl thiazolyl tetrazolium (MTT) assay after blocking LAT3 expression with either shRNA targeted to LAT3 or a small molecular inhibitor BCH (2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid). LAT3 mRNA and protein expression was detected in leukemia cell lines, but not in normal PBMNCs. Using K562 cells, it was found that cellular proliferation and mTOR pathway activity were significantly reduced when LAT3 was blocked with either shRNA or BCH. Our results suggest that leukemia cell proliferation can be significantly suppressed by blocking LAT3. This finding may lead to a new strategy to develop clinical therapy for the treatment of acute myeloid leukemia.
Amino Acid Transport Systems, Basic ; antagonists & inhibitors ; genetics ; metabolism ; Amino Acids, Cyclic ; pharmacology ; Blotting, Western ; Cell Line, Tumor ; Cell Proliferation ; Cell Survival ; drug effects ; genetics ; Cells, Cultured ; Dose-Response Relationship, Drug ; Gene Expression Regulation, Leukemic ; genetics ; HL-60 Cells ; Humans ; Jurkat Cells ; K562 Cells ; Leukemia, Erythroblastic, Acute ; genetics ; metabolism ; pathology ; Phosphorylation ; drug effects ; RNA Interference ; Reverse Transcriptase Polymerase Chain Reaction ; TOR Serine-Threonine Kinases ; metabolism

OBJECTIVETo investigate the proliferation-inhibiting and multidrug-resistant reversing effect of bortezomib on human HL-60 cells, and to explore the mechanism of bortezomib-induced proliferation inhibition in human leukemia cells.

METHODSThe multidrug resistant leukemia cell lines HL-60/DNR and HL-60/VCR cells were used as models, and sensitive HL-60 cells as a control. The cytotoxicity of bortezomib on HL-60, HL-60/DNR, HL-60/VCR cells were measured by MTT method, and the non-cytotoxicity dose was determined as reversible dose. The cells were divided into 4 experimental groups: HL-60/DNR + DNR, HL-60/DNR + DNR + bortezomib, HL-60/VCR + VCR, HL-60/VCR + VCR + bortezomib. The bortezomib resistant reversal fold was calculated. The levels of XIAP, cIAP-1, and cIAP-2 mRNA and proteins expression and the activation of NF-κB of the HL-60/DNR, HL-60/VCR cells were examined by quantitative real time RT-PCR and western blot respectively after treated with gradually increasing concentrations of bortezomib (10, 40, 80 nmol/L) for 48 hours.

RESULTSBortezomib inhibited the cell growth of HL-60, HL-60/DNR, and HL-60/VCR in a concentration-dependent manner. The IC(50) values were (28.90 ± 3.99), (81.19 ± 9.34), and (73.48 ± 8.94) nmol/L, respectively. After treated with 10nmol/L bortezomib for 48 hours, the IC(50) value of DNR to HL-60/DNR decreased from (12.90 ± 1.75) µmol/L to (3.54 ± 0.57) µmol/L (P < 0.01), and that of VCR to HL-60/VCR from (33.25 ± 7.28) µmol/L to (9.97 ± 1.15) µmol/L (P < 0.01). The reversal fold (RF) values were 3.32 ± 0.53 and 2.64 ± 0.28, respectively. Bortezomib down-regulated the levels of XIAP, cIAP-1, and cIAP-2 mRNA and protein expression and inhibited the NF-κB activation in a concentration-dependent manner.

CONCLUSIONBortezomib can inhibit the proliferation of HL-60 cells and reverse multidrug-resistance in the cells. The possible mechanism is associated with down-regulation of IAPs expression.

Boronic Acids ; pharmacology ; Bortezomib ; Cell Proliferation ; drug effects ; Drug Resistance, Multiple ; Drug Resistance, Neoplasm ; HL-60 Cells ; Humans ; Leukemia ; genetics ; metabolism ; pathology ; NF-kappa B ; metabolism ; Pyrazines ; pharmacology ; RNA, Messenger ; genetics

To investigate the effect of a microsomal prostaglandin E synthase-1 (mPGES-1) inhibitor MK886 on cell cycle of the human acute myeloid leukemia HL-60 cells. HL-60 cells were treated with different concentration of MK886 (10, 25, 50 µmol/L) for 24 h. Flow cytometry, Western blot and ELISA were used to measure cell cycle, cyclin D1, mPGES-1, PGE(2), Akt, P-Akt and C-MYC. The results indicated that after treated with MK886, the percentage of HL-60 cells decreased in G(0)/G(1) phase and increased in S phase, and expressions of mPGES-1, cyclin D1, P-Akt and C-MYC and synthesis of PGE(2) decreased significantly. It is concluded that MK886 can arrest HL-60 cells in G(0)/G(1) phase, the mechanism of which is possibly associated to inhibition of mPGES-1 expression, reduction of PGE(2) synthesis, suppression of Akt phosphorylation and C-MYC expression, down-regulation of cyclin D1 expression.
Cell Cycle ; drug effects ; HL-60 Cells ; Humans ; Indoles ; pharmacology ; Intramolecular Oxidoreductases ; antagonists & inhibitors ; Leukemia ; metabolism ; pathology ; Prostaglandin-E Synthases

OBJECTIVETo investigate the synergistic effects of carnosic acid (CA) with arsenic trioxide (As₂O₃) on proliferation and apoptosis in HL-60 human myeloid leukemia cells, and the major cellular signaling pathway involved in these effects.

METHODSHL-60 cellular proliferation was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) analysis. Cell cycle distribution and apoptosis were monitored by flow cytometry. The activation of casepase-9, Bcl-2-associated agonist of cell death (BAD), p-BAD, p27, phosphatase and tensin homolog deleted on chromosome ten (PTEN), Akt, p-Akt was assessed by Western blot analysis. The expression of PTEN mRNA was tested by reverse transcription polymerase chain reaction (RT-PCR) analysis.

RESULTSCA reduced HL-60 cell viability in a dose- and time-dependent manner, and induced G1 arrest and apoptosis. Moreover, CA upregulated PTEN expression, blocked the Akt signaling pathway, subsequently inhibited phosphorylation of BAD, reactivated caspase-9, and elevated levels of p27. CA also augmented these effects of As₂O₃.

CONCLUSIONCA might be a novel candidate of the combination therapy for leukemia treatment; these effects were apparently associated with the modulation of PTEN/Akt signaling pathway.

Apoptosis ; drug effects ; Arsenicals ; pharmacology ; Base Sequence ; Blotting, Western ; Cell Cycle ; drug effects ; DNA Primers ; Diterpenes, Abietane ; pharmacology ; Drug Synergism ; HL-60 Cells ; Humans ; Leukemia, Myeloid, Acute ; metabolism ; pathology ; Oxides ; pharmacology ; PTEN Phosphohydrolase ; metabolism ; Plant Extracts ; pharmacology ; Proto-Oncogene Proteins c-akt ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Signal Transduction ; drug effects