Inhibition of Telomerase with hTERT Antisense Increases Susceptibility of Leukemic Cells to CDDP-induced Apoptosis

Objective: To investigated the e?ect of inhibition of telomerase with hTERT antisense on leukemic cells (HL-60 and K562) to CDDP-induced apoptosis. Methods: Antisense phosphorothioate oligodeoxynucleotide (AS PS-ODN) was synthesized and puri?ed. Telomerase activity was detected by Telomerase PCR ELASA kit and cell apoptosis was observed by morphological method and determined by ?owcytometry. Results: AS PS-ODN could signi?cantly inhibit telomerase activity by down regulat- ing the hTERT expression, and increase the susceptibility of leukemic cells to CDDP-induced apoptosis. Conclusion: Inhibition of telomerase with hTERT antisense can increases the susceptibility of leukemic cells to CDDP-induced apoptosis.

CHARACTERIZING FLUORESCENCE LIFETIME OF NAD(P)H IN HUMAN LEUKEMIC MYELOID CELLS AND MONONUCLEAR CELLS

The aim of this er vito study was to explore the potential of using the fluorescence lifetime of intraellular reduced nicotinamide adenine dinucleotide(phosphate)(NAD(P)H)as a label-free indicator to characterize the di ferencs between human leukemic myeloid cells and normal mononuclear cells(MNC).The steady-state and time-resolved autofuorescence of two human leukemic myeloid cell lines(K562,HL60)and MNC were measured by a spectrofuorimeter.According to excitation-enmission matrix(EEM)analysis,the optimal emission of NAD(P)H in these cells suspensions occurred at 445 nm.Furthermore,the fuorescence lifetimes of NAD(P)H in leukemic myeloid cells and MNC were determined by fitting the time-resolved autofuorescence data.The mean fuorescence lifetimes of NAD(P)H in K562,HL60,and MNC cells were 557±1.19,4.45±0.71,and 7.31±0.60 ns,respectively.There was a significant diference in the mean lifetime of NAD(P)H between leukemic myeloid cells and MNC(p<0.05).The difference was essentally caused by the change in relative concentration of free and protein-bound NAD(P)H.This study suggests that the mean fuorescence lifetime of NAD(P)H might be a potential label-free indicator for differentiating leukemic myeloid cells from MNC.

Expression and Fuactional Role of HERG1, K^+ Channels in Leukemic Cells and Leukemic Stem Cells

In order to investigate the expression and functional role of HERG1 K+ channels in leukemic cells and leukemic stem cells (LSCs), RT-PCR was used to detect the HERG1 K+ channels expression in leukemic cells and LSCs. The functional role of HERG1 K+ channels in leukemic cell proliferation was measured by MTT assay, and cell cycle and apoptosis were analyzed by flow cy- tometry. The results showed that herg mRNA was expressed in CD34+/CD38-, CD123+ LSCs but not in circulating CD34+ cells. Herg mRNA was also up-regulated in leukemia cell lines K562 and HL60 as well as almost all the primary leukemic cells while not in normal peripheral blood mononuclear cells (PBMNCs) and the expression of herg mRNA was not associated with the clinical and cytoge- netic features of leukemia. In addition, leukemic cell proliferation was dramatically inhibited by HERG K+ channel special inhibitor E-4031. Moreover, E-4031 suppressed the cell growth by induc- ing a specific block at the G1/S transition phase of the cell cycle but had no effect on apoptosis in leukemic cells. The results suggested that HERG1 K+ channels could regulate leukemic cells prolif- eration and were necessary for leukemic cells to proceed with the cell cycle. HERG1 K+ channels may also have oncogenic potential and may be a biomarker for diagnosis of leukemia and a novel potential pharmacological target for leukemia therapy.

THE PRELIMINARY APPLICATION OF IN SITU HYBRIDI-ZATION IN DETECTING PROTO-ONCOGENES EXPRESSION IN HUMAN LEUKEMIC CELLS

An in situ hybridization technique with 35S labelled proto-oncogene probes (c-myc & c-fes) was used to detect their expression in bone marrow cells of 22 cases of leukemia of various types and immature granulocytes and erythroblasts of 16 nomal myelograms as controls. Both c-myc and c-fes were detectable in leukemic cells as well as in immature granulocytes and erythroblasts of normal bone marrow, but the expression extent varied in different cases. The levels of c-myc expression in leukemic cells were higher than those in controls (P<0.001). There was no difference of c-fes expression in two groups of bone marrow cells (P>0.05). This technique provides us a new method in studying variations of proto-oncogene expression in leukemic cells.

Expressions of IL-10 on leukemic cells in acute leukemic patients and its significance

Objective: To explore the expressions of IL-10 on leukemic cells in acute leukemia patients and its significance. Methods: The expressions of IL-10 on leukemic cells in thirty patients was measured by indirect immunofluorescence technique. Results: Observed yellow-green bright fluorescence on leukemic cells membrane, the positive rate of cells was 10-80%, there were 18 patients expressing IL-10 (18/30, 60%) positively, among them 11 with ANLL (11/19, 58%) and 7 with ALL (7/11, 64%) respectively while that of peripheral mononucleate cells in control group was 13%. Compared with that in the control group, there was a significant increase of positive rate in ANLL and ALL but with no significant difference between ANLL and ALL. Conclusion: IL-10 secreted by leukemic cells, contributed to the immunosuppressive state at the tumor site. This is probably one of the important mechanisms of acute leukemic escape.

CHARACTERIZATION OF A HUMAN HERPES VIRUS－6（HHV－6） AND EPSTEIN－BARR VIRUS（EBV） ASSOCIATED LEUKEMIC CELL LINE，J6－1

This report characterizes the J6-1 cell line derived from a Chinese acute myelomonocytic leukemia patient and previously reported to be associated with EBV. These studies showed that J6-1 cells were also infected with HHV-6 as demonstrate at the DNA level by PCR and Southern blot hybridization and by expression of HHV-6 early membrane antigen on the J6-1 cell surface. Further characterization showed J6-1 was co-infected with EBV type 2. Generally, cells infected with EBV type 2 do not grow well in vitro. However, J6-1 , although difficult to maintain in vitro, has been grown for 15 years. Possibly, co-infection with HHV6 confers this property. In this regard, J6-1 cells exhibited density dependent growth which could be inhibited with an anti-HHV-6-MA monoclonal antibody(MAb). In contrast, anti-HHV-6-VCA MAb stimulated the J6-1 cell proliferation. Electron microscopic analysis showed that, morphologically, there were two types of J6-1 cell, one with lymphoblastoid features and one with a monocytoid appearance. Accordingly, the flow profile of the J6-1 cell line showed heterogeneity. with two populations comprised of CD15-, CD19+ cells with low light scatter(small cells) and a population with greater light scatter(larger cells) which was CD15+ , CD19+. The population was negative for progenitor cell markers(CD33, 34 ), and T cell markers. Southern analysis showed no T cell receptor rearrangement, however there was a clonal JH and kappa light chain expressing population. Glycocytochemical analysis showed several endogenous lectin receptors on the J6-1 cell surface: BSA-Xylose, BSA-Rhamnose, BSAGal. BSA-Lac. This cell line shares many characteristics with other monocytic/ lymphoblastoid cell lines isolated elsewhere and provides circumstantial evidence linking Herpes viruses, as least as co- factors,to leukemia cell growth.

Inhibition of Leukemic Cell Telomerase Activity by Antisense Phosphorothioate Oligodeoxynucleotides

Objective To evaluate the effect of human telomerase reverse transcriptase (hTERT) gene antisense oligodeoxynucleotide (ASODN) ontelomerase activity in K562 cells.Methods Telomerase activity was determined by polymerase chain reaction enzyme-linked immunoassay (PCR-ELISA) in K562 cellstreated with ASODN and hTERT mRNA expression was detected by reverse transcriptase polymerase chain reaction (RT-PCR).Results The hTERT mRNA level was decreased, and teloraerase activity was significantly inhibited when the K562 cells were treated withASODN for 48 h.Conclusion It is suggested that hTERT ASODN might specifically inhibit telomerase activity of K562 cells at translation level, and it isfurther proved that hTERT gene has significant correlation with telomerase activity.

High frequency of CD34+CD38-/low immature leukemia cells is correlated with unfavorable prognosis in acute myeloid leukemia

AIM To evaluate the importance of the CD34+CD38-cell population when compared to the CD34+CD38+/low and CD34+CD38+/high leukemic cell sub-populations and to determine its correlations with leukemia characteristics and known prognostic factors, as well as with response to therapy and survival.METHODS Two hundred bone marrow samples were obtained at diagnosis from 200 consecutive patients with newly diagnosed acute myeloid leukemia(AML) were studied between September 2008 and December 2010 at our Institution(Hematology Department, Lyon, France). The CD34/CD38 cell profile was analyzed by multiparameter flowcytometry approach using 8 C panels and FACS CANTO and Diva software(BD Bioscience).RESULTS We analyzed CD34 and CD38 expression in bone marrow samples of 200 AML patients at diagnosis, and investigated the prognostic value of the most immature CD34+CD38-population. Using a cut-off value of 1% of CD34+CD38-from total "bulk leukemic cells" we found that a high(> 1%) level of CD34+CD38-blasts at diagnosis was correlated with advanced age, adverse cytogenetics as well as with a lower rate of complete response after induction and shorter disease-free survival. In a multivariate analysis considering age, leukocytosis, the % of CD34+ blasts cells and the standardized cytogenetic and molecular risk subgroups, a percentage of CD34+CD38-leukemic cells > 1% was an independent predictor of DFS [HR = 2.8(1.02-7.73), P = 0.04] and OS [HR = 2.65(1.09-6.43), P = 0.03].CONCLUSION Taken together, these results show that a CD34/CD38 "backbone" for leukemic cell analysis by multicolour flowcytometry at diagnosis provides useful prognostic information.

ELECTRON MICROSCOPIC OBSERVATION OF DIFFERENTIATION OF LEUKEMIC CELL CLONE AFTER CFU-MIX CULTURE

By scanning and transmission electron microscopy, leukemlc celb were obwrved after CFU-Mix culture. Even though granulocytlc growth factor, erythropoietin and lymphocytlc growth factor were added at vitor, acute leukemlc celb still showed defects In differentiation and maturation. These were characterized by abnormal colony which consisted of smooth cells, bizarre shape, nuclear-cytoplasmic asynchrony In development, and appearance of nuclear bleb. However, chronic myelogenous leukemlc celb were more nature than the acute ones, manifesting in normal colony with finger- like projections and ruffled membrane. Macrophages and eosinophils could be observed. It b suggested that there b a difference In differentiation between acute and chronic leukemia cells.

HPLCASSAY FOR INTRACELLULAR ACCUMULATION OF VERAPAMIL IN VER-RESISTANT HUMAN LEUKEMIC CELL SUSLINES AND THEIR PARENTAL CELL LINES

Objective: To establish a HPLC method using fluorometric detection for quantitatively determinating intracellular accumulation of verapamil (VER). Methods: Chromatography column was packed with spherisorb ODS(250×4.6 mm,10 μm).The mobile phase consisted of the mixture of methanol:NaAC (0.01 mol/L): diethylamine (65:35:0.25). The detect wavelength was 280/310 nm (Ex/Em). Results: The standard curve showed a good correlation between concentration and peak area within the range of 5-50 ng/ml. RSD was 0.86%, and recovery radio of loading sample, 100%. The detection limit for cell sample was 0.2-148 ng/ml. Intracellular accumulation of VER was observed to decrease from a 13 fold to 5 fold in K562/ADM cells, and from a 3.5 fold to 4.3 fold in K562/VER cells and from a 2.1 fold to 6.5 fold in K562/ADM/VER cells, compared with the relevant control cells. Conclusion: HPLC method was proved to be sensitive and specific for using to quantitatively determine the intracellular accumulation of VER.

Apoptosis of Leukemia Cells Induced by CD34^+ Cells Transferred Exogenous Fas Ligand

To assess the value of CD34 + cells transferred exogenous Fas ligand (FasL) in inducing apoptosis of human leukemic cells, the CD34 + cells transfected with F asL or without, pretreated with mitomycin C, was mixed with leukemic cell line U937 cells in presence or absence of daunorubicin (DNR) or cytosine arabinoside (Ara C). After l8 h, apoptosis of cells was detected by FCM and TUNEL. Induced for l8 h by CD34 + cells transfected with FasL or without, the ratio of apoptos is of U937 cells was (5.0±1.3) %, (10.8±0.6) % ( P < 0.01), respectively. Induced by FasL +CD34 ++DNR, FasL +CD34 ++Ara C, the ratio was (13.4±1.0) % ( P < 0.05), (17.9±1.3)% ( P <0.01), respectively. The result demonstrated that CD34 + cells transfected with exogenous FasL could induce apoptosis of human leukemic cells and showed a cytotoxic synergistic effect when used in combination with chemotherapeutic drugs, suggesting that it was possible to develop a new method in treatment of leukemia.

The effects of IL-10 on acute leukemic immune evasion

Objective: To explore the effects of IL-10 on acute leukemic immune evasion.Methods: Plasma concentrations of IL-10 were measured by ELISA in 56 first-visit acute leukemic patients.And expressions of IL-10 on leukemic cells in 30 patients were measured by indirect immunofluorescence technique. Results:Compared with those in control group,IL-10 concentrations increased significantly in first-visit acute leukemic patients.And there was a slight but not significant decrease of IL-10 in patients with acute lymphocytic leukemia(ALL) compared with those with acute non lymphocytic leukemic(ANLL).After intensive chemotherapy,there was a significant decrease of IL-10 in completely remitted(CR) patients,especially in those with ANLL,but there was still a significant increase compared with those in control group.The positive rate of cells giving out yellow-green bright fluorescence on membranes was 10%-80%;there were 18 patients expressing IL-10(18/30,60%) positively:among them 11 with ANLL(11/19,58%) and 7 with ALL(7/11,64%) respectively while that of peripheral mononucleate cells in control group was 13%.Compared with that in control group,there was a significant increase of positive rate in ANLL and ALL but with no significant difference between ANLL and ALL.Conclusion: Probably as one of important mechanisms of acute leukemic immune evasion,IL-10 secreted by leukemic cells,contributing to the immunosuppressive state at the tumor site,increase significantly in acute leukemic patients.

Sunitinib Reduces Acute Myeloid Leukemia Clonogenic Cells in Vitro and Has Potent Inhibitory Effect on Sorted AML ALDH+ Cells

Sunitinib is an orally administered, multi-target tyrosine kinase inhibitor that has been approved by the FDA for the treatment of renal cell carcinoma and imatinib resistant gastro-intestinal tumors. Anti-leukemic activity of sunitinib has been examined in early clinical trials with limited success. However, recent trials on acute myeloid leukemia (AML) patients carrying FLT3 mutations have shown promising results. Effects of sunitinib on leukemic clonogenic cells and potential leukemic stem cells have not been examined so far. We analyzed the anti-proliferative and apoptotic properties of sunitinib on AML-derived cell lines. We also tested the effect of sunitinib on AML patient derived clonogenic cells (AML-CFC), as well as flow-sorted potential leukemic progenitors. Peripheral blood or bone marrow samples were obtained from newly diagnosed AML patients and flow sorted for CD34+ CD133+ or ALDH+ cells. Umbilical cord blood derived CD34+ cells were used as normal controls. Sunitinib induced growth arrest and apoptosis in AML derived cell lines. In addition, 7 μM sunitinib induced 75% reduction of AML-CFC as compared to DMSO treated control (±6.79%;n = 4). In contrast, 7 μM sunitinib treatment of umbilical cord blood derived normal CD34+ cells showed 29% reduction in AML-CFC (±6.77%;n = 5). Treatment of ALDH+ cells sorted from 2 AML cases and CD34+ CD133+ cells from one patient showed reduction of AML-CFC on treatment with sunitinib. Our study highlighted a potent anti-proliferative and proapoptotic effect of sunitinib on AML cell lines, AML patient derived clonogenic cells and potential leukemic stem cells.

Flared inflammatory episode transforms advanced myelodysplastic syndrome into aplastic pancytopenia:A case report and literature review

BACKGROUND Myelodysplastic syndrome(MDS)is a hematological neoplasm,and an increase in myeloblasts is representative of leukemic hematopoiesis in advanced MDS.Lowrisk MDS usually exhibits deranged autoimmunity resembling that of aplastic anemia(AA),whereas advanced MDS is characterized by a phenotype of immune exhaustion.MDS can be normo/hyperplastic or hypoplastic.Generally,bone marrow cellularity and myeloblasts increase with disease progression.Transformation from advanced MDS to AA-like syndrome with leukemic cell regression has not previously been reported.CASE SUMMARY A middle-aged Chinese woman had a 4-year history of leukocytopenia.Six months prior to admission,the patient developed gradually worsening fatigue and performance status.The leukocytopenia further progressed.She was diagnosed with MDS with excess blasts-2 based on increased bone marrow cellularity and an increased percentage of myeloblasts on marrow and blood smears,an increased percentage of cluster of differentiation(CD)34+CD33+progenitors in immunotyping analysis,a normal karyotype in cytogenetic analysis,and the identification of somatic mutations in CBL,KMT2D and NF1 in molecular analysis.Initially,neutropenia was the predominant hematological abnormality,with mild anemia and thrombocytosis,and the degree of fatigue was far more severe than the degree of anemia.In the following months,the patient experienced several febrile episodes.Intravenous antibiotic treatments were able to control the febrile episodes,but the elevated inflammatory indices persisted.The hematological parameters dramatically fluctuated with the waxing and waning of the inflammatory episodes.With recurrent flares of the inflammatory condition,agranulocytosis and severe anemia developed,with mild thrombocytopenia.During the patient’s hospitalization,computed tomography(CT)scans revealed the presence of extensive inflammatory lesions involving the lungs,mediastinum,pleura,gastrointestinal tract,peritoneum and urinary tract,with imaging features suggestive of the reactivation of disseminated tuberculosis.Reevaluation of the bone marrow smears revealed that the cellularity became hypoplastic,and the leukemic cells regressed,suggesting that both normal and leukemic hematopoiesis had been heavily suppressed.Immunological analysis of the bone marrow samples revealed a decreased percentage of CD34+cells and an immunological signature resembling that of severe AA(SAA),confirming the regression of the leukemic cells by autoimmune-mediated attacks.The patient demonstrated resistance to multiple drugs,including antituberculotics,recombinant human granulocyte colony-stimulating factor,broad-spectrum antibiotics,voriconazole,ganciclovir,immune suppressants,eltrombopag and intravenous immunoglobulin,which further worsened the hematological injury and patient’s performance status.The patient eventually died of overwhelming infection and multidrug resistance.CONCLUSION Advanced MDS can transform to aplastic cytopenia with leukemic cell regression and an immunological signature of SAA during inflammatory flare-ups.

Tuberculosis-induced aplastic crisis and atypical lymphocyte expansion in advanced myelodysplastic syndrome:A case report and review of literature

BACKGROUND Myelodysplastic syndrome(MDS)is caused by malignant proliferation and ineffective hematopoiesis.Oncogenic somatic mutations and increased apoptosis,necroptosis and pyroptosis lead to the accumulation of earlier hematopoietic progenitors and impaired productivity of mature blood cells.An increased percentage of myeloblasts and the presence of unfavorable somatic mutations are signs of leukemic hematopoiesis and indicators of entrance into an advanced stage.Bone marrow cellularity and myeloblasts usually increase with disease progression.However,aplastic crisis occasionally occurs in advanced MDS.CASE SUMMARY A 72-year-old male patient was definitively diagnosed with MDS with excess blasts-1(MDS-EB-1)based on an increase in the percentages of myeloblasts and cluster of differentiation(CD)34+hematopoietic progenitors and the identification of myeloid neoplasm-associated somatic mutations in bone marrow samples.The patient was treated with hypomethylation therapy and was able to maintain a steady disease state for 2 years.In the treatment process,the advanced MDS patient experienced an episode of progressive pancytopenia and bone marrow aplasia.During the aplastic crisis,the bone marrow was infiltrated with sparsely distributed atypical lymphocytes.Surprisingly,the leukemic cells disappeared.Immunological analysis revealed that the atypical lymphocytes expressed a high frequency of CD3,CD5,CD8,CD16,CD56 and CD57,suggesting the activation of autoimmune cytotoxic T-lymphocytes and natural killer(NK)/NKT cells that suppressed both normal and leukemic hematopoiesis.Elevated serum levels of inflammatory cytokines,including interleukin(IL)-6,interferon-gamma(IFN-γ)and tumor necrosis factor-alpha(TNF-α),confirmed the deranged type I immune responses.This morphological and immunological signature led to the diagnosis of severe aplastic anemia secondary to large granule lymphocyte leukemia.Disseminated tuberculosis was suspected upon radiological examinations in the search for an inflammatory niche.Antituberculosis treatment led to reversion of the aplastic crisis,disappearance of the atypical lymphocytes,increased marrow cellularity and 2 mo of hematological remission,providing strong evidence that disseminated tuberculosis was responsible for the development of the aplastic crisis,the regression of leukemic cells and the activation of CD56+atypical lymphocytes.Reinstitution of hypomethylation therapy in the following 19 mo allowed the patient to maintain a steady disease state.However,the patient transformed the disease phenotype into acute myeloid leukemia and eventually died of disease progression and an overwhelming infectious episode.CONCLUSION Disseminated tuberculosis can induce CD56+lymphocyte infiltration in the bone marrow and in turn suppress both normal and leukemic hematopoiesis,resulting in the development of aplastic crisis and leukemic cell regression.

Induction of apoptosis by homoharringtonine in G1 phase human chronic myeloid leukemic cells

Background Homoharringtonine (HHT) is a cephalotaxine ester derived from an evergreen tree found wildely throughout southern China, which has antileukemic activities against a variety of acute myeloid leukemic cells. For the sake of illustrating the mechanisms of HHT in the treatment of leukemia, we assessed the effect of HHT on the apoptosis of human chronic myeloid leukemic cell line K562.Methods The apoptosis of K562 cells induced by HHT was analyzed by transmission electron microscopy, agarose gel electrophoresis of DNA, flow cytometry and terminal deoxyribonucleotidyl transferase-mediated dUTP-biotin nick labeling.Results Characteristic apoptosis-related features emerged in K562 cells after exposed to HHT at a concentration 0.05-100 μg/ml. Transmission electron microscopy of HHT treated K562 cells displayed chromatin condensation and aggregation under the nuclear membrane, nuclear fragmentation and apoptosis body formation. Typical DNA ladder in agarose gel electrophoresis was observed in the cells exposed to HHT. The cell cycle analysis measured by flow cytometry showed G1 phase cells decreased with the increase of S phase cells while apoptosis was induced by HHT in K562 cells. The percentage of apoptotic cells in K562 cells treated with 50 μg/ml of HHT decreased significantly when pretreated with 1 μg/ml of cycloheximide, 0.05 μg/ml of Actinomycin D respectively.Conclusions HHT has apoptotic effects on K562 cells. The HHT induced apoptosis mainly of the cells in G1 phase and this process required RNA transcription and protein synthesis.

Expression of the human multidrug resistance gene mdr1 in leukemic cells and its application in studying P-glycoprotein antagonists

Objective To investigate the retrovirus mediated transfer and expression of multidrug resistance gene (mdr1) in hematopoietic cells and to develop a model for studying the possible reversal of the MDR mediated phenotype Methods A retroviral vector HaMDR expressing the human mdr1 gene was packaged by PA317 cells with a titer of up to 8 5×10 5CFU/ml K562 leukemia cells were infected with MDR retrovirus, and transfectant K562/MDR cells were generated The integration and expression of the exogenous mdr1 gene in K562/MDR cells were determined by polymerase chain reaction and flow cytometry The reversal ability of P glycoprotein (P gp) antagonists was analyzed by in vitro drug sensitivity, accumulation and efflux of rhodamine 123 (Rh123) in this model Results Transduction with amphotropic MDR retrovirus resulted in integration and expression of the mdr1 gene in the resistant cells, where an aberrant splicing transcript of the mdr1 gene was found The K562/MDR cells displayed a classic MDR phenotype with a 41-78 fold resistance to vincristine and colchicine in comparison with parental K562 cells The drug sensitivity of K562/MDR cells to vincristine can be completely restored by cyclosporin A (CsA, 2?mg/L) and Cremophor EL (CRE 132?mg/L), either individually or in combination ( P <0 05) CsA (3 ?mg/L) can block the efflux pump function of P gp shown by the significantly increased accumulation and efflux reduction of Rh123 in K562/MDR cells Conclusions Retroviral vector HaMDR allows transfection with high level expression of the mdr1 gene in human myeloid progenitor cells K562 The transfected K562/MDR provides a simple, sensitive model for developing antagonists of P gp and studying their mechanism of action

Effects of Bufalin on Up-regulating Methylation of Wilm's Tumor 1 Gene in Human Erythroid Leukemic Cells

Objective To explore the effects of bufalin on inhibiting proliferation, up-regulating methylation of Wilm’ tumor 1 gene (WT1) as well as its possible mechanisms in human erythroid leukemic (HEL) cells. Methods The HEL cells were treated with bufalin at various concentrations to observe cellular morphology, proliferation assay and cell cycle. The mRNA and protein expression levels of WT1 were detected by reverse transcription polymerase chain reaction (RT-PCR), Western blot and immunocytochemistry, DNA methylation of WT1 and protein expression levels of DNA methyltransferase 3a (DNMT3a) and DNMT3b were analyzed by methylation-specific PCR, and Western blot respectively. Results The bufalin was effective to inhibit proliferation of HEL cells in a dose-dependent manner, their suppression rates were from 23.4%±2.1% to 87.2%±5.4% with an half maximal inhibit concentration (IC50) of 0.046 μmol/L. Typical apoptosis morphology was observed in bufalin-treated HEL cells. The proliferation index of cell cycle decreased from 76.4%±1.9% to 49.7%±1.3%. The expression levels of WT1 mRNA and its protein reduced gradually with increasing doses of bufalin, meanwhile, the methylation status of WT1 gene changed from unmethylated into partially or totally methylated. While, the expression levels of DNMT3a and DNMT3b protein gradually increased by bufalin treatment in a dose-dependent manner. Conclusions Bufalin can not only significantly inhibit the proliferation of HEL cells and arrest cell cycle at G0/G1 phase, but also induce cellular apoptosis and down-regulate the expression level of WT1. Our results provide the evidence of bufalin for anti-leukemia, its mechanism may involve in increasing WT1 methylation status which is related to the up-regulation of DNMT3a and DNMT3b proteins in erythroid leukemic HEL cells.

Effects of Danshen Injection(丹参注射液) on Inhibiting Proliferation and Inducing Apoptosis through Down-Regulation of Mutant JAK2 Gene and Its Protein Phosphorylation in Human Erythroid Leukemic Cells

Objective： To explore the effects of Danshen Injection （丹参注射液） on inhibition proliferation, inducing apoptosis and its possible mechanisms on human erythroid leukemic （HEL） cells. Methods： The commercial Chinese patent medicine of Danshen Injection was extracted and isolated from Chinese herb of Salvia miltiorrhiza bung. The inhibition effects of proliferation were assayed by 3-（4,5-dimethylthiazol-2-yl）-2, 5-diphenyltetrazolium bromide （M＇l-r） method in HEL cells treated by Danshen Injection at various concentrations for 48 h. The cellular apoptosis was observed in morphology, analyzed by flow cytometry with annexin V and propidium iodide （PI） staining, and examined by DNA degradation ladder on agarose gel electrophoresis. Meanwhile, the expression levels of mutant Janus kinasez （JAK2） gene and phosphorylation-JAK2 （P-JAK2） protein were detected by allele specific-polymerase chain reaction and Western blot. ]Results： The proliferation of HEL cells was effectively inhibited by Danshen Injection in a dose-dependent manner, with suppression rates from 19.46 ± 2.31% to 50.20 ± 5.21%. Typical apoptosis cells was observed in Danshen Injection treated HEL cells, the rates of annexin V positive cells increased obviously in a dose-dependent manner, as well as the DNA degradation ladder of apoptosis revealed on gel electrophoresis. The expression levels of mutant JAK2 gene and P-JAK2 protein reduced gradually with increasing dosage of Danshen injection. Conclusion： Danshen Injection could not only significantly inhibit the proliferation, but also induce apoptosis in HEL cells; down-regulation of the mutant JAK2 gene and P-JAK2 protein expressions are probably one of its molecular mechanisms.

The Experimental and Clinical Study on the Effect of Curcumin on Cell Cycle Proteins and Regulating Proteins of Apoptosis in Acute Myelogenous Leukemia

To investigate whether the Bcl- 2 gene family is involved in m odulating mechanism of apoptosis and change of cell cycle protein induced by curcumin in acute myeloid leukemia HL - 6 0 cell line and primary acute m yelogenous leukem ic cells,the Bcl- 2 family member Mcl- 1,Bax and Bak and cell cycle proteins including P2 7kipl,P2 1wafl,cyclin D3and p Rbp- were selected and their ex- pression detected by SABC imm uno- histochem ical stain m ethod.The attitude of sub- G1 peak in DNA histogram was determined by FCM.The TU NEL positive cell percentage was identified by term inal deoxynucleotidyl transferase (Td T ) - m ediated Biotin d U NP end labeling technique.It was found that when HL - 6 0 cells were treated with 2 5μm ol/ L curcumin for 2 4 h,the expression level of Mcl- 1was down- regulated,but that of Bax and Bak up- regulated time- dependently.There was significant difference in the expression level of Mcl- 1,Bax and Bak between the curcumin- treated groups and control group(P<0 .0 5 - 0 .0 1) .At the sam e time,curcumin had no effect on progress of cell cycle in prim aty acute m yelogenous leukemia at newly diagnosis,but could in- crease the peak of Sub- G1 (P<0 .0 5 ) ,and down- regulate the expression of Mcl- 1and up- regulate the expression of Bax and Bak with the difference being statistically significant.The expression of P2 7kipl,P2 1wafl and p Rbp- were elevated and thatof cyclin D3decreased in the presence of curcum in. These findings suggested thatthe Bcl- 2 gene fam ily indeed participated in the regulatory process of apoptosis induced by curcumin in HL - 6 0 cells and AML cells.Curcumin can induce apoptosis of primary acute myelogenous leukemic cells and disturb cell cycle progression of HL - 6 0 cells.The m echanism appeared to be m ediated by perturbing G0 / G1 phases checkpoints which associated with up- regulation of P2 7kipl,P2 1wafl and p Rbp- expression,and down- regulation of cyclin D3.