Role of Daxx in inhibiting megakaryocytic differentiation of K562 cells

AIM: To examine the effects of death domain-associated protein (Daxx) overexpression on the viability and megakaryocytic differentiation of K562 cells. METHODS: Daxx overexpression in the K562 cells was established. The expression of Daxx was detected by fluorescence microscopy, fluorescence quantitative real-time PCR and Western blot after transfection. CCK-8 assay was used to detect the cell viability after overexpression of Daxx. The expression of CD41 and CD61 in phorbol 12-myristate 13-acetate (PMA) induced K562 cells was detected by flow cytometry. The protein levels of Daxx and p-ERK were determined by Western blot. Nitroblue tetrazolium (NBT)-reducing test was used to assess leukemia cell differentiation in Daxx-overexpressing K562 cells and control cells. The expression of CD41 and CD61 induced by PMA in Daxx-overexpressing K562 cells was analyzed by flow cytometry. The protein levels of Daxx and p-ERK were also examined by Western blot. RESULTS: The stable overexpression of Daxx in the K562 cells was established. The viability was reduced in Daxx-overexpressing K562 cells. The expression of CD41 and CD61 was significantly increased after PMA induction in the K562 cells (P < 0.01). The protein expression of Daxx was reduced, but the protein level of p-ERK was increased. The expression of CD41 and CD61 was reduced after PMA induction in Daxx-overexpressing K562 cells (P < 0.01). The protein level of p-ERK was also reduced. CONCLUSION: Daxx overexpression inhibits the growth, megakaryocytic differentiation and production of p-ERK in the K562 cells.     

Apoptosis induced by berbamine in K562 cells correlates with the expression levels of bcr/abl gene and P210

AIM: To explore the effect of berbamine(BER) on apoptosis in K562 cells and its possible molecular mechanisms. METHODS: The apoptosis rate was measured by flow cytometry while electron microscopy and DNA electrophoresis were used to evaluate the characteristic changes of apoptosis, RT-PCR and Western blot were used to examine the expression levels of apoptosis related gene bcr/abl and BCR/ABL protein. RESULTS: By FCM, the apoptosis rate of K562 cells treated with 8.0 mg/L BER for 24 h and 72 h increased from (29.20±3.82)% to (61.77±4.35)% (P＜0.01); The typical apoptosis morphologic changes and the DNA ladder were more clearly observed. After treated with BER 0 to 16.0 mg/L for 24 h, the expression levels of bcr/abl mRNA and P210 (semiquantity value) decreased quickly from 1.19±0.02 to 0.73±0.02 (P＜0.01) and from 1.04±0.02 to 0.63±0.01 (P＜0.01), respectively. CONCLUSION: BER induces apoptosis of K562 cells in a time-and-concentration-dependent manner, the decline of bcr/abl mRNA and P210 may play an important role in the apoptotic effect of BER in K562 cells. BER could be used as a new clinical trials for bcr-abl⁺ diseases such as CML.     

The effect of antisense bcr-abl oligonucleotides on the growth of K562 cells

AIM:To study the effect of bcr- abl gene antisense phosphorothioate oligonucleotides(Aspo) on K562 cell line and explore its significance in chrenic myelogeneous leukemia (CML) gene therapy.METHODS:Cells were exposed to oligomeis, observed by inverted microscope.Cells inhibitory rate were determined by 0.4 trypan blue exclusion . CFU-K562 were cultured in 0.8 % methylcellulose . P210 was measured by flow cytomety RESULTS: K562 cells were treated with Aspo, they still grew in clone state and show antisense sequence specific and dose dependent. When the concentration of Aspo was more than Spznol/L, the growth of cells was inhibited and P210 was down regulated or completely suppressed, and the greatest growth inhibition was at 120h . There was signifi-cant inhibition of cell proliferation in a rang‘cells number from 1×10⁴/mL to 5×10⁴/mL after treatment with 10unol/L Aspo. b2a2 Aspo was also effect on K562 cells which expressing b3a2 mRNA.CONCLUSION: bcr-abl Aspo has a specific growth inhibition effect on K562 cells, and worths further study in CML gene therapy.     

Valproate enhances imatinib-induced apoptosis and down-regulates Bcr/Abl mRNA and phosphorylated protein kinase B in chronic myeloid leukemia cell line K562

AIM：To investigate the effects of valproate and imatinib on the apoptosis of chronic myeloid leukemic cell line K562. METHODS：K562 cells were divided into 3 groups and treated with valproate, imatinib and cotreatment, respectively. Cell cycle, apoptosis, the mRNA expression of Bcr/Abl, total protein kinase B (PKB) and phosphorylated PKB (p-PKB) were analyzed. RESULTS：The apoptotic rates in valproate group, imatinib group and cotreatment group were (11.47±0.25)%, (28.43±1.70)% and (57.73±4.38)%, respectively (P<0.05). No obvious difference was observed in cell cycle between cotreatment group and monodrug group. Bcr/Abl mRNA and p-PKB in the above 3 groups were (0.00±0.00), (64.17±12.27), and (0.00±0.00) ×10 9 copies/(g total mRNA), respectively (P<005), and 0.25±0.02, 0.17±0.01 and 0.08±0.01, respectively (P<0.05). No apparent difference of PKB was found in the 3 groups. CONCLUSION：Valproate enhances imatinib-induced apoptosis and may link to the down-regulation of Bcr/Abl mRNA and p-PKB in chronic myeloid leukemic cell line K562.     

Cellular biological effects of matrine on K562 and K562/Vin cells

AIM: To investigate the cellular biological effects of matrine on K562 and K562/Vin cells and discuss the anticancer mechanism of matrine. METHODS: MTT assay was used to detect the IC₅₀ of matrine on these two cell lines and the reversal effect of matrine on K562/Vin cell's resistance to vincristine. In addition, the growth curve of cells was drawed. The p-glycoprotein (P-gp) expression was determined by immunohistochemistry analysis. The morphological changes of cells under light microscopy and the structural changes under transmission electron microscope were observed. RT-PCR assay was used to detect the hTERT-mRNA expression. RESULTS: The IC₅₀ of matrine was 3.4, 4.6 mmol·L ^-1 for K562 and K562/Vin cells, respectively. Matrine (4.0 mmol·L ^-1) inhibited the growth of K562, K562/Vin cells, 2.0 mmol·L ^-1 matrine inhibited expression of P-gp and with 492.4 reversal index. Matrine killed K562 cells by inducing the apoptosis and the same effect on K562/Vin cells was also observed. The hTERT-mRNA expression of K562 cells were also inhibited by matrine. CONCLUSIONS: Matrine enhanced the cytotoxicity of vincristine in K562/Vin cells, induced the apoptosis of K562 and K562/Vin cells, also inhibited the hTERT-mRNA expression in K562 cells. It shows that matrine would be an effective anticancer medicine.     

Salinomycin inhibits proliferation and induces apoptosis of Gleevec-resistant chronic myeloid leukemic cell line K562/Glv

AIM: To study the effect of salinomycin on inhibiting proliferation and inducing apoptosis of Gleevec-resistant chronic myeloid leukemia cell line K562/Glv. METHODS: The inhibitory effect of salinomycin on the growth of K562/Glv cells was detected by CCK-8 assay in vitro. Flow cytometry was used to observe apoptosis, mitochondria membrane potential (ΔΨ_m), reactive oxygen species (ROS) and the concentration of intracellular Ca²⁺ ([Ca²⁺]_i) in K562/Glv cells. The activity of caspase-3, -8 and -9 was measured by the method of colorimetry. The levels of cytochrome C, Bcl-2, Bax, β-catenin and phosphorylated low-density lipoprotein receptor-related protein 6 (p-LRP6) were determined by Western blotting. RESULTS: Salinomycin inhibited the growth of K562/Glv cells in a dose-dependent manner. Salinomycin at concentration of 0.2 μmol/L inhibited the growth of the cells with the inhibitory rate of (36.70±2.31)%. The cell apoptotic rate was (19.66±2.23)%. Salinomycin at concentration of 0.2 μmol/L decreased the level of ΔΨ_m, and increased the levels of ROS, cytochrome C and[Ca²⁺]_i in the cells. Salinomycin also increased the activity of caspase-3, -8 and -9 in the cells, reduced the ratio of Bcl-2/Bax, and attenuated the levels of β-catenin and p-LRP6. CONCLUSION: Salinomycin induces the apoptosis of Gleevec-resistant myeloid leukemia cell line K562/Glv via Bcl-2/Bax and mitochondria-dependent pathways, and inhibits the cell growth through Wnt signal pathway.     

Knockdown of RALA by siRNA inhibits cell proliferation and induces apoptosis in human leukemic K562 cells

AIM: To investigate the effect of siRNA-induced knockdown of v-ral simian leukemia viral oncogene homolog A(RALA) on proliferation and apoptosis of chronic myelogenous leukemia(CML) K562 cells. METHODS: The chemically synthesized siRNA targeting to RALA gene was transfected into K562 cells using Lipofectamine^TM 2000. The proliferation and viability of K562 cells were detected by MTT assay and trypan blue dye exclusion. The expression levels of RALA mRNA and protein were determined by quantitative real-time PCR and Western blotting,respectively. The cell apoptosis was analyzed using flow cytometry by double staining with annexin V and propidium iodide, and the apoptotic morphological changes were detected by Hoechst 33258 staining. RESULTS: RALA siRNA significantly down-regulated RALA mRNA and protein expression in K562 cells(P<0.05). The proliferation of K562 cells in RALA siRNA group was inhibited compared with control group(P<0.05). The apoptotic rate was much higher in RALA siRNA group than that in negative control group(P<0.05). The apoptotic morphological changes were observed in the nuclei of K562 cells transfected with RALA siRNA. CONCLUSION: The siRNA-mediated knockdown of RALA results in inhibition of proliferation and induction of apoptosis in K562 cells, indicating that RALA might be used as a potential therapeutic target in chronic myelogenous leukemia.     

Apelin-13 inhibits nicotine-induced apoptosis of H9c2 cells via PI3K/Akt signaling pathway

AIM:To investigate the effect of apelin-13 on nicotine-induced apoptosis of cardiomyocytes and its potential molecular mechanism. METHODS:Rat H9c2 cells were treated with nicotine (10 μmol/L) to induced apoptosis. Flow cytometry was used to detect apoptotic rate. Western blot was used to determined the expression of related proteins. RESULTS:Compared with control group, nicotine treatment significantly increased the apoptotic rate of the H9c2 cells (P<0.01), and the protein levels of apoptosis-related proteins Bax and cleaved caspase-3, but markedly decreased the protein levels of Bcl-2, p-Akt, p-PI3K and APJ (P<0.05). Compared with nicotine group, apelin-13+nicotine significantly decreased the apoptotic rate of the H9c2 cells (P<0.01) and the the protein levels of Bax and cleaved caspase-3, but markedly increased the protein levels of Bcl-2, p-Akt, p-PI3K and APJ (P<0.05). Compared with apelin-13+nicotine group, apelin-13+nicotine+PI3K/Akt inhibitor LY294002 significantly increased the apoptotic rate of the H9c2 cells (P<0.01) and the protein levels of Bax and cleaved caspase-3, but markedly decreased the protein levels of Bcl-2, p-Akt and p-PI3K (P<0.05). CONCLUSION:Apelin-13 inhibits nicotine-induced apoptosis of H9c2 cells through PI3K/Akt signaling pathway.     

Effects of p38 MAPK on SETD4 expression and location in p38 +/+ and p38 -/- cells treated with sodium arsenite

AIM: To investigate the expression and location of SET domain-containing 4(SETD4) protein in p38 ^+/+ and p38 ^-/- cells treated with sodium arsenite(NaAsO₂). METHODS: The expression and location of SETD4 were detected in different cells with or without NaAsO₂ treatment by Western blotting and immunofluorescence technique. RESULTS: The expression of SETD4 was detectable in both murine- and human-derived cells. Its distribution was found to be located in the whole cell, mainly in the cytoplasm. Further investigation also suggested that the protein expression of SETD4 was reduced in both p38 ^+/+ and p38 ^-/- cells 6 h after NaAsO₂ treatment. Moreover, SETD4 protein was translocated from cytoplasm to nucleus in p38 ^+/+ cells treated with NaAsO₂, which was unobvious in p38 ^-/- cells. CONCLUSION: SETD4 protein is expressed in various cells derived from different species and tissues, and it is mainly located in cytoplasm. NaAsO₂ treatment influences the expression of SETD4, and induces the translocation of SETD4 protein to nucleus, which might be involved in the p38 MAPK signal pathway.     

Overexpression of Smad7 inhibits TGF-β-induced Smad2 mRNA and protein expression in peritoneal mesothelial cells

AIM: To investigate the role of Smad7 in the Smad2 expression induced by transforming growth factor-β₁ (TGF-β₁) in rat peritoneal mesothelial cells (PMCs).METHODS: Rat PMCs were cultured at different doses of TGF-β₁ (0，1.25，2.5，10 μg/L) for different time (0，5，15，30，60，120 min).PCDNA3-Smad7 was then transfected into cultured rat PMCs by lipofectamine, and the cells were stimulated like the above.Endogenous Smad2 and Smad7 expression was evaluated by RT-PCR and Western blotting.RESULTS: TGF-β₁ induced increase in Smad2 mRNA and protein expression at 5 min, peaked at 30 min, and declined to baseline levels at 120 min, which was in a time-dependent manner.TGF-β₁ also induced Smad7 mRNA expression at 5 min, and then declined, down to the lowest at 30 min, but at 60 min it increased again.Smad2, Smad7 mRNA and protein expression induced by TGF-β₁ were also dose-dependent.After transfection, overexpressions of Smad7 mRNA and protein in rat PMCs were observed, which did not decline with time.The expression of Smad2 mRNA significantly decreased by 33%, 56%, 67%, 71%, 63% and 57% (P<0.05), the expression of Smad2 protein declined by 78%，89%，89%，88% and 76% (P<0.05) respectively at 0, 5, 15, 30, 60 and 120 min.CONCLUSION: Overexpression of Smad7 inhibits Smad2 gene and protein expression in peritoneal mesothelial cells.Smad7 may be a negative regulator of TGF-β₁ signaling.     

Expression of fusion protein anti-HER2-ScFv-GFP in insect cells and binding to surface of breast cancer cells

AIM: To express a recombinant fusion protein anti-human epidermal growth factor receptor-2 single-chain variable fragment with green fluorescent protein (anti-HER2-ScFv-GFP) using the insect cells-Bac-to-Bac baculovirus expression system and to analyze the binding function of this fusion protein with HER2 on the surface of the breast cancer cells. METHODS: Human anti-HER2-ScFv gene from mice was fused with GFP gene. To obtain the recombinant plasmid pFAST Bac-to-Bac HT A/anti-HER2-ScFv-GFP, we inserted it into Bac-to-Bac baculovirus expression plasmid pFAST Bac-to-Bac HT A. The identified recombinant plasmid was transferred into Escherichia coli DH10Bac to allow the generation of a recombinant bacmid. After transfected the recombinant virus bacmid into the insect cells Tn-5B1-4, the recombinant virus was collected to infect Tn-5B1-4. SDS-PAGE and Western blotting analysis were used to verify the expression product in Tn-5B1-4. The fusion protein was purified with Ni²⁺-NTA affinity chromatography. The purified fusion protein was bound to the surface of HER2-positive breast cancer cells SKBR3 and HER2-negative breast cancer cells MCF7. The binding effects on the surface of breast cancer cells were observed under laser confocal microscope. RESULTS: The fusion gene anti-HER2-ScFv-GFP was successfully constructed with the length of 1 539 bp. The green fluorescence was also observed in Tn-5B1-4 cells infected with the recombinant virus under fluorescent microscope. A 60 kD protein was examined and confirmed by SDS-PAGE and Western blotting. Under laser confocal microscope, strong green fluorescence was observed on the surface of the HER2-positive breast cancer cells SKBR3. However, no green fluorescence was observed on the surface of HER2-negative breast cancer cell MCF7. Obvious green fluorescence on the surface of HER2-positive breast cancer cell SKBR3 was also found after the cells were eluted with 1×PBS. CONCLUSION: The fusion protein anti-HER2-ScFv-GFP was successfully expressed in insect cells Tn-5B1-4, and can firmly bind to the surface of breast cancer cells SKBR3 and emit the green fluorescent light.     

HTPP-MDC inhibits replication and subcellular localization of hepatitis B virus in HepG2.2.15 cells

AIM：To investigate the antiviral effect of hepatocyte-targeting and cell-penetrating peptide and Musca domestica cecropin (HTPP-MDC) fusion polypeptide against hepatitis B virus (HBV) in vitro, and to observe the penetrating ability of HTPP-MDC in hepatocytes. METHODS： HepG2.2.15 cells and Chang liver cells were co-cultured in vitro with HTPP-MDC at different concentrations. MTT assay was used to detect the cytotoxicity of HTPP-MDC in vitro. The levels of HBsAg, HBeAg and HBV DNA in HepG2.2.15 cell culture supernatants were measured by ELISA and real-time fluorescence quantitative PCR. The penetrating ability of HTPP-MDC was detected by laser confocal microscopy. RESULTS：The levels of HBsAg, HBeAg and HBV DNA in the supernatants of HepG2.2.15 cells treated with HTPP-MDC were remarkably reduced. The inhibitory effect of HTPP-MDC depended on the dose and action time of the drug. FITC-labeled HTPP-MDC was observed inside the cells under laser confocal microscope. CONCLUSION：HTPP-MDC strongly inhibits HBV replication in HepG2.2.15 cells. The penetrating ability of HTPP-MDC into hepatocytes indicates that HTPP-MDC is useful in clinic therapy for chronic hepatitis B-related diseases in the future.     

Astragalus injection inhibits the expression of JNK3 mRNA after hypoxia/hypoglycemia and reoxygenation in hippocampal neurons of rats

AIM: To investigate the effect of astragalus injection on the expression of c-jun N terminal kinase (JNK3) mRNA interrelated with apoptosis after hypoxia/hypoglycemia and reoxygenation in hippocampal neurons of rats. METHODS: The hippocampal neurons cultured for eight days were divided into 4 groups: normal control group, original astragalus injection group, hypoxia/hypoglycemia and reoxygenation group, astragalus injection group. Hypoxia/ hypoglycemia and reoxygenation group, astragalus injection group and original astragalus injection group were treated with hypoglycemia and reoxygenation after deprived of oxygen and glucose for 30 min. Methods of in situ hybridization and RT-PCR were used respectively to measure the expression of JNK3 mRNA after hypoxia/hypoglycemia and reoxygenation 0 h, 0.5 h, 2 h, 6 h, 24 h, 72 h and 120 h. RESULTS: In normal control group the volume of hippocampal neuronal nucleolus was accretion, cellular tuber was distinct and cytokinesis was dyed by yellow a lot. In hypoxia/hypoglycemia and reoxygenation group the hippocampal neuronal nucleolus was crimple, cellular tuber was shrinked, large number of cytokinesis was dyed by yellow and yellow granule was observed. Compared with normal control group, the numbers of JNK3 mRNA positive neuronal cells at each time point increased obviously in the hypoxia/hypoglycemia and reoxygenation group (P<0.05). The change of neuronal configuration and the numbers of JNK3 mRNA positive neuronal cells in original astragalus injection group accorded with hypoxia/ hypoglycemia and reoxygenation group (P>0.05). In astragalus injection group the hippocampal neuronal nucleolus was crimple slightly and segmental cytokinesis was dyed by yellow.Compared to hypoxia/hypoglycemia and reoxygenation group, the numbers of JNK3 mRNA positive neuronal cells at each time point were less obviously in the astragalus injection group besides 120 h (P<0.05). Compared to normal control group, the mean optic density of expression of JNK3 mRNA in hippocampal neurons of rats at each time point increased obviously in hypoxia/ hypoglycemia and reoxygenation group (P<0.05). Compared to hypoxia/hypoglycemia and reoxygenation group, the mean optic density of JNK3 mRNA expression at each time point in original astragalus injection group had no obvious change (P>0.05), however the mean optic density of JNK3 mRNA expression in hippocampal neurons of rats at each time point decreased obviously in the astragalus injection group besides 120 h (P<0.05). CONCLUSION: Astragalus injection inhibits the expression of JNK3 mRNA after hypoxia/hypoglycemia and reoxygenation, accordingly inhibits hippocampal neuronal apoptosis.     

Potentiation of the action of phorbol ester by heparin in human CNE2 cells: Association with enhanced expression of c-jun,p53 and p21

AIM: To measure the effect of addition of heparin to TPA on cell proliferation and apoptosis in CNE2 cells and investigate the possible molecular mechanisms underlying heparin and TPA interaction on cell proliferation and apoptosis. METHODS: Cell viability and cell cycle were determined by cell counting and flow cytometry.Apoptosis was evaluated by terminal deoxynucleotidyl transferase-mediated dUPT nick-end labeling (TUNEL)and agarose gel electrophoresis. The expression of c-jun, c-fos, p21 and p53 was examined by Western blot. RESULTS: TPA alone inhibited CNE2 cell proliferation and evoked apoptosis associated with typical morphological changes and DNA fragmentation,which was augmented when heparin was added. Compared with TPA or heparin alone, TPA plus heparin obviously enhanced the number of TUNEL-positive cells from 23%±1.2% to 51%±0.9%. After exposure to different concentrations of heparin (with or without TPA) for 24 h, CNE2 cells were accumulated G₀/G₁ phase. There was a decrease in the number of cells in S phase by the combined heparin and TPA treatment compared to heparin or TPA alone. Western blot analysis revealed that TPA induced the increases in c-jun and p53, p21 protein expression and the levels were remarkably increased following heparin in combination with TPA treatment,whereas no significant change in c-fos was detected. CONCLUSION: These results suggest that heparin synergistically potentiates the action of TPA in CNE2 cells, which may be associated with the increase in c-jun protein level and the upregulation of p21, p53 protein expression.     

Antigen-loaded dendritic cells and CD40L triggers the killing effects of cytotoxic T lymphocytes on K562 cells in vitro

AIM:To investigate the anti-tumor effects of special cytotoxic T lymphocytes (CTLs) activated by dendritic cells (DCs) loaded with antigens and CD40L in vitro.METHODS:Peripheral blood mononuclear cells were isolated by Ficoll density gradient centrifugation from normal human heparinized blood.The adherent cells were cultured with granulocyte-macrophage colony stimulating factor (GM-CSF),interleukin-4 (IL-4),alpha tumor necrosis factor (TNF-α),DCs were co-cultured with frozen-thawed antigen of K562 cells and CD40L,then triggered T cells into specific CTLs.RESULTS:Most suspended cells exhibited distinctive morphological features of DCs which expressed CD40 96%,CD86 97%,CD80 77%,CD1a 69%,and gained the powerful capacity to stimulate proliferation of allogenic lymphocytes.Under the effector∶target ratio of 20∶1,CTLs derived from cultures with DCs and frozen-thawed antigen of K562 cells were showed 71.3% cytotoxicities against K562 cells.CTLs derived from cultures with DCs loaded with frozen-thawed antigen and CD40L were showed 86.9% cytotoxicities against K562 cells.Cytotoxicities by CTLs derived from cultures with unloaded DCs against K562 cells were 37.6% and cytotoxicities by monocytes were 21.1%.Cytotoxicities by CTLs derived from experiment groups were stronger than control groups (P<0.05).CONCLUSIONS:The tumor antigen-pulsed DCs induces efficient and specific anti-tumor immunity,CTLs derived from cultures containing DCs pulsed with CD40L show the strongest cytolytic activities on K562 cells.     

Expression relevance of GATA-1 and miR-451a in erythroid differentiation of K562 cells under hypoxia

AIM To investigate the expression relevance of GATA binding protein-1 (GATA-1) and microR?NA-451a (miR-451a) in erythroid differentiation of human chronic myeloid leukemia K562 cells under hypoxia. METHODS The K562 cells were divided into 2 groups: normoxia group and hypoxia (1% O₂) group, and 40 μmol/L hemin chloride was used to induce K562 cell differentiation for 48 and 72 h. The mRNA expression of γ-globin was detected by RT-qPCR, hemoglobin production was observed by benzidine staining, and flow cytometry was used to detect CD235a expression for verifying erythroid differentiation model. The protein expression of GATA-1 during K562 cell differentiation under normoxia and hypoxia was determined by Western blot. RT-qPCR was used to detect the mRNA expression of GATA-1 and the expression level of miR-451a, and their correlation was analysis. The K562 cells were infected by lentivirus for over-expression or knock-down of GATA-1. Meanwhile, the morphological changes of the cells in the above groups were analyzed by Wright-Giemsa staining method to clarify the erythroid differentiation of K562 cells. The expression miR-451a was detected by RT-qPCR after GATA-1 over-expression or knock-down. REULTS: Under normoxia and hypoxia conditions, the expression levels of γ?-globin and CD235a and the positive rate of benzidine staining at 48 and 72 h were significantly higher than those at 0 h (P<0.05).At 72 h, the expression levels of γ?-globin and CD235a and the benzidine staining positive rate in hypoxia group were significantly higher than normoxia group (P<0.05). The expression of GATA-1 mRNA and miR-451a under hypoxia showed an upward trend during the erythroid differentiation of K562 cells, and was significantly higher than that in normoxia group at 72 h (P<0.05). Correlation analysis showed that the mRNA expression of GATA-1 was positively correlated with miR-451a expression under hypoxia (P<0.01). After over-expression of GATA-1 under hypoxia, the expression of γ-globin and CD235a, the positive rate of benzidine staining, and the cell counts of size augmentation, nuclear deflection and nuclear shrinkage at 72 h were significantly higher than those in negative control group (P<0.05). After knock-down of GATA-1 under hypoxia, the expression of γ-globin and CD235a, the benzidine staining positive rate, and the cell counts of size augmentation, nuclear deflection and nuclear shrinkage at 72 h were significantly lower than those in negative control group (P<0.05). Compared with negative control group under hypoxia, the expression of miR-451a was significantly increased after GATA-1 over-expression (P<0.05), while the expression of miR-451a was significantly decreased after GATA-1 knock-down (P<0.05). CONCLUSION Hypoxia increases the expression of GATA-1 and then up-regulates miR-451a to promote erythroid differentiation of K562 cells.     

Cloning of hCD154 gene from human activated peripheral blood mononuclear cell and expression of hCD154-GST fusion protein in prokaryote

AIM:To express recombinant hCD154-GST fusion protein, to prepare anti-hCD154 monoclonal antibody, and to investigate the effect of anti-hCD154 monoclonal antibody on graft rejection. METHODS AND RESULTS: Total RNA was prepared from human peripheral blood mononuclear cell (PBMC) activated with 10ng/mL PMA and 1 μg/mL PHA for 8h, the total RNA was reversetranscribed to cDNA. The entire coding region and a part of the 3'non-coding regions were amplified by PCR using a pair of primers designed and synthesized according to the sequence of human CD154 gene from gene bank. The amplified product, a 820bp DNA fragment was cloned into pGEX-4T-1 plasmid expressing glutathione S-transferase(GST). The cloned insert was identified by double digestion of the cloned pGEX-4T-1 plasmid with retriction enzymes BamHⅠand EcoRⅠ.The fusion protein expression plasmid of PGEX-4T-1/hCD154 was constructed, then transformed to E coli BL21. The human CD154-GST fusion protein expression was induced by IPTG in BL21. The expression of recombinant 26kD GST and 55kD human CD154-GST fusion protein were confirmed by SDS-PAGE. CONCLUSION: We have express the recombinant human CD154-GST fusion protein. The expressed hCD154-GST fusion protein will be used to prepare anti-hCD154 monoclonal antibody, to investigate the role of anti-CD154 monoclonal antibody on graft rejection.     

Marsdenia tenacissima extract inhibits viability and induces apoptosis of melanoma cells via regulating PI3K/AKT/mTOR signaling pathway

AIM:To evaluate the effects of Marsdenia tenacissima extract (MTE) on the viability and apoptosis of mouse skin melanoma cell line B16-F10. METHODS:B16-F10 cells were treated with MTE at different doses for 24 h or at different doses for different time, and the cell viability was measured by MTT assay. The apoptosis was analyzed by flow cytometry. The protein levels were determined by Western blot. Meanwhile, the cells were treated with insulin-like growth factor-1 (IGF-1) and the protein levels were measured again. RESULTS:The cells were treated with MTE for 72 h for further study according to the results of pre-experiments. MTE at 100 and 200 mg/L inhibited the viability of B16-F10 cells and decreased the protein expression of Ki67 and PCNA significantly. MTE induced the apoptosis of B16-F10 cells as demonstrated by increasing cleaved caspase-3 and cleaved caspase-9. Meanwhile, MTE down-regulated the protein levels of p-PI3K, p-AKT and mTOR. In addition, IGF-1, the activator of PI3K/AKT/mTOR pathway, alleviated the effects of MTE on the viability and apoptosis markedly. CONCLUSION:MTE inhibits the viability and induces the apoptosis of melanoma cells by down-regulating PI3K/AKT/mTOR signaling pathway.     

TGF β1 inhibits the maturation of dendritic cells and down-regulates TLR4 expression

AIM: To investigate the effects of transforming growth factor β1 (TGF-β1) on murine-derived dendritic cells (DC). METHODS: Murine bone marrow cells were cultured with GM-CSF and TGF-β1 to develop TGF β-DC. Then they were stimulated by lipopolysaccharide (LPS). Their phenotypes were assessed by flow cytometry (FCM). The allogeneic stimulating capacity of DC was measured by mixed lymphocyte reaction (MLR) using BrdU ELISA method. IL-12 p70 protein was detected by ELISA and the expressions of Toll like receptor 4 (TLR4) on DCs were measured by semi-quantitative RT-PCR and FCM. RESULTS: Compared to immature DC (imDC) cultured with GM-CSF alone, the expressions of CD80, CD86, I-Ab and CD40 in TGF β-DC were lower. The TGF β-DC was resistant to maturation by LPS. Maturation resistance was evident from a failure to up-regulate CMs, to stimulate larger T cell proliferation and to increase secretion of IL-12 p70. Down-regulation of TLR4 expression on TGF β-DC was also found. CONCLUSION: TGF-β1 inhibits the expression of co-stimulatory molecules on DC. It is resistant to maturation stimulus (LPS) and might be linked with TLR4 down-regulation.