Effects of genistein on proliferation,apoptosis and invasiveness in methotrexate-resistant human choriocarcinoma JAR/MTX cells and it s mechanism

AIM:To study the effects of genistein on JAR/MTX cell proliferation, apoptosis and invasion and it's mechanism in vitro. METHODS:MTT assay, Annexin-Ⅴ and propidium iodide label analysis and invasion assay were used to determine the effects of genistein on proliferation, apoptosis and invasiveness in JAR/MTX methotrexate- resistant human choriocarcinoma cells. RT-PCR was used to estimate the relative mRNA amounts of estrogen receptor(ER), MTA3 and snail in the cells. Western blotting and gelatin zymography assay were used to estimate the relative protein amounts of MMP-2, MMP-9 and E-cadherin in the cells. RESULTS:After treatment of genistein, the proliferation and invasiveness of JAR/MTX cells were decreased significantly in a dose-dependent manner. 10 μmol/L genistein induced apoptosis, whereas 25, 50, 100 μmol/L genistein induced apoptosis and necrosis significantly. Genistein led to an increase in ERβ, MTA3 mRNA and E-cadherin protein expression, and decreases in the amounts for snail mRNA and MMP-2 and MMP-9 protein expression of JAR/MTX cells. CONCLUSIONS:Genistein inhibits the cell proliferation by inducing cell apoptosis and necrosis. Genistein also may inhibit JAR/MTX cell invasion in part through the upregulation of E-cadherin and downregulation of MMP-2 and MMP-9. The signal transduction pathway of invasion suppression induced by genistein in JAR/MTX cells may be as follows: MTA3→snail→ E-cadherin.     

Sphingosine kinase 1 enhances invasion and migration of non-small-cell lung cancer cells by ERK1/2 signaling pathway

AIM To explore the effects of sphingosine kinase 1 (SphK1) on the migration and invasion of non-small-cell lung cancer (NSCLC) cells and its mechanism. METHODS Thirty-one tumor specimens, which were surgically resected and routinely histologically confirmed as NSCLC, and matched adjacent lung tissues were selected. Immunohistochemical staining and RT-qPCR were used to detect the expression of SphK1. The pcDNA3.1-SphK1 vector (SphK1 group), empty pcDNA3.1 vector control (NC group), SphK1 siRNA (siSphK1 group) or control siRNA (siNC group) was transfected into human lung adenocarcinoma A549 cells, and the protein levels of SphK1, E-cadherin, fibronectin and p-ERK1/2 were determined by Western blot. The effects of over-expression of SphK1 and inhibition of ERK1/2 on migration and invasion of A549 cells were evaluated by Transwell assays. RESULTS SphK1 was highly expressed in the NSCLC tissues and was associated with tumor stage. SphK1 over-expression significantly promoted the migration and invasion of A549 cells, increased the protein levels of p-ERK1/2 and fibronectin, and decreased the protein expression of E-cadherin (P<0.05), but the opposite result was observed after SphK1 interference. The ERK1/2 inhibitor U0126 significantly inhibited the up-regulation of p-ERK1/2 and fibronectin levels and the down-regulation of E-cadherin expression induced by SphK1 over-expression, and also inhibited the invasion and migration of A549 cells promoted by SphK1 over-expression (P<0.05). CONCLUSION SphK1 may reduce E-cadherin protein levels, increase fibronectin protein levels, and promote the invasion and migration of NSCLC cells through ERK1/2 signaling pathway.     

Effects of microRNA-483-3p on human glioma cells

AIM:To investigate the effects of microRNA (miRNA)-483-3p on the growth and migration of human glioma cell line A172 and its potential mechanisms.METHODS:The abundance of miRNA-483-3p in human embryonic kidney 293 cells and different human glioma cell lines (A172,U251 and SHG44) was measured by RT-qPCR.After down-regulation of miRNA-483-3p by transfection of inhibitor in the A172 cells,the cell viability,cell cycle distribution and cell migration were detected by CCK-8 assay,flow cytometry and Transwell assay,respectively.Furthermore,the protein levels of cell cycle-related molecules and epithelial-mesenchymal transition markers were measured by Western blot.Luciferase reporter assay was used to predict and verify the target gene of miRNA-483-3p.RESULTS:miRNA-483-3p was highly expressed in human glioma cells.Knockdown of miRNA-483-3p inhibited A172 cell viability,arrested cell cycle and decreased cell migration rate.Furthermore,the protein levels of cyclin D1,cyclin-dependent kinase 4,phoshorylated retinoblastoma protein,N-cadherin and vimentin were significantly decreased after knockdown of miRNA-483-3p,accompanied with the up-regulation of E-cadherin and β-catenin protein expression.Luciferase reporter assay demonstrated that Smad4 was a potential target gene of miRNA-483-3p.Down-regulation of Smad4 in the A172 cells transfected with miRNA-483-3p inhibitor partially reversed the effect of miRNA-483-3p on cell viability and migration.CONCLUSION:Knockdown of miRNA-483-3p restrains the growth and migration of A172 cells by targeting Smad4.     

Genistein inhibits proliferation of human oral cancer TCA8113 cells through suppression of VEGF expression

AIM: To investigate the effect of genistein on the proliferation of human oral cancer TCA8113 cells and to explore the underlying mechanisms.METHODS: The cell proliferation was examined by MTT assay, cell counting and colony formation assay. Western blotting was employed to examine the protein levels of vascular endothelial growth factor(VEGF), extracellular signal-regulated kinase(ERK) and p-ERK. RESULTS: Genistein significantly inhibited the proliferation of TCA8113 cells in a concentration-dependent fashion. Moreover, genistein dose-dependently decreased the protein levels of VEGF, ERK and p-ERK. The expression of VEGF was also blunted by U0126, a specific inhibitor of ERK. U0126 and axitinib, a VEGF receptor antagonist, both significantly inhibited the proliferation of TCA8113 cells. CONCLUSION: Genistein inhibits the proliferation of TCA8113 cells, which may be related to its inhibitory effect on ERK expression and activation, thus subsequently decreasing the expression of VEGF.     

Sinomenine inhibits viability,migration and invasion of human ovarian cancer SKOV3 cells

AIM:To investigate the effect of sinomenine on the viability, migration and invasion of human ovarian cancer SKOV3 cells and its possible mechanism. METHODS:The SKOV3 cells were treated with sinomenine at different concentrations for 12 h, 24 h and 48 h. CCK-8 assay was employed to detect the effects of sinomenine on the viability of the SKOV3 cells. Flow cytometry was used to analyze the cell cycle distribution. The cell migration and invasion abilities were measured by Transwell assay. Western blot was used to determine the protein levels of cyclin A, cyclin D1, E-cadherin and matrix metalloproteinase-9 (MMP-9). RESULTS:Sinomenine remarkably inhibited the viability of SKOV3 cells and IOSE80 cells in a time-dependent and dose-dependent manner (P<0.05), and the IC₅₀ values of 48 h were 2.12 mmol/L and 17.35 mmol/L, respectively. In a dose-dependent manner, sinomenine induced G₀/G₁ and S phase arrest in SKOV3 cells (P<0.05), suppressed the migration and invasion abilities of SKOV3 cells (P<0.05), down-regulated the protein levels of cyclin A, cyclin D1 and MMP-9 (P<0.05), and up-regulated the protein level of E-cadherin (P<0.05). CONCLUSION:Sinomenine inhibits the viability, migration and invasion of human ovarian cancer SKOV3 cells most likely via down-regulation of the protein levels of cyclin A, cyclin D1 and MMP-9, and up-regulation of the protein level of E-cadherin.     

Down-regulation of GEP100 inhibits the invasive ability of pancreatic cancer cell AsPC-1 in vitro

AIM: To study the effects of down-regulation of guanine nucleotide exchange protein 100 (GEP100) on the invasive ability of pancreatic cancer cell AsPC-1 in vitro. METHODS: The clone of AsPC-1 cells with stable knock-down of GEP100 by transfection of pSuper-retro-puro-GEP100 was established. The invasive ability was evaluated by matrigel invasion assay and the migratory ability of the cells was examined by crossing-river test. The protein expression of E-cadherin was determined by Western blotting. RESULTS: The invasive ability was inhibited significantly in matrigel invasion assay (P<0.01). The penetrated cells were 46.62±5.25/field in GEP100 knock-down group, 115.40±12.46/field in mock group and 111.82±10.82/field in non-transfected group, respectively. The migratory ability of the cells was just inhibited slightly, showing a crossing-river time period of (52.68±4.12) h, which was a little bit longer than that in non-transfected group (48.60±5.24) h and mock group (47.56±3.42) h without statistical difference. Down-regulation of GEP100 resulted in a morphological change of AsPC-1 cells from mesenchymal type to epithelial type and an obvious up-regulation of E-cadherin protein was observed (P<0.05). CONCLUSION: Suppression of GEP100 inhibits the invasive ability of AsPC-1 cells significantly without obvious influence on the migratory ability. The cells show a transformation from mesenchymal type to epithelial type with increased E-cadherin expression. The above results indicate that GEP100 might play an important role in the invasive ability of pancreatic cells through regulation of the E-cadherin expression.     

Glucosylceramide synthase upregulates apoptosis-related gene bcl-2 expression via MEK/ERK signaling pathway in leukemia multidrug-resis-tant cell line

AIM: To investigate whether glucosylceramide synthase (GCS) regulates apoptosis-related gene bcl-2 expression via MEK/ERK signaling pathway, thus enhancing drug resistance of K562/A02 human leukemia multidrug resistant cell line. METHODS: siRNA targeting GCS was transfected into K562/A02 cells. Bcl-2, p-ERK and total ERK expression at mRNA and protein levels after GCS knockdown were detected by real-time PCR and Western blotting. After exposed to MEK-ERK pathway inhibitor U0126, the expression of Bcl-2 at mRNA and protein levels also was analyzed by real-time PCR and Western blotting, respectively. The viability of the cells was evaluated by CCK-8 assay. RESULTS: The expression of GCS and Bcl-2, as well as MEK/ERK signaling were significantly inhibited in K562/A02 cells by GCS siRNA transfection compared with negative control group. Inactivation of MEK/ERK signaling due to U0126 treatment decreased Bcl-2 mRNA and protein levels in a concentration-dependent manner, and sensitized K562/A02 cells to adriamycin. CONCLUSION: GCS may affect the expression of apoptosis-related gene bcl-2 by MEK/ERK signaling pathway, thus regulating multidrug resistance of human leukemia K562/A02 cells.     

Effects of marrow stromal cell-mediated microenvironment on human lung adenocarcinoma A549 cells

AIM: To investigate the effects of marrow stromal cell line HS-5 on human lung adenocarcinoma A549 cells in the tumor microenvironment. METHODS: The effects of HS-5 cell-conditioned medium (HS-5-CM) on the viability and migration ability of A549 cells were detected by MTT assay and wound-healing assay. After treatment with HS-5-CM, the expression of CX3C chemokine receptor 1 (CX3CR1) at mRNA level in the A549 cells was examined by qPCR. The protein levels of p-ERK and ERK in the A549 cells treated with MAPK/ERK pathway inhibitor U0126 were observed by Western blot, the migration ability of the A549 cells was measured by wound-healing assay, and the protein expression of CX3CR1 was determined by Western blot. RESULTS: HS-5-CM promoted the viability and migration ability of the A549 cells (P<0.01). The expression of CX3CR1 at mRNA level in the A549 cells was increased after treatment with HS-5-CM. MAPK/ERK inhibitor U0126 inhibited the activation of MAPK/ERK signaling pathway (P<0.01), and reduced the migration ability (P<0.01) and the expression of CX3CR1 (P<0.05) in the A549 cells. CONCLUSION: HS-5-CM significantly promotes the A549 cell viability and migration ability. Activation of MAPK/ERK signaling pathway and the expression of CX3CR1 may play a important role in this process.     

Recombinant human defensin α1 induces proliferation of rat glomerular mesangial cells in vitro

AIM: To study the effects and mechanism of recombinant human defensin α₁ on cell proliferation in cultured rat glomerular mesangial cells.METHODS: The influences of defensin α₁ at various concentrations on rat 1097 mesangial cell line cultured in vitro were evaluated with MTT assay.The different concentrations of U0126,signal-regulated protein kinase (MEK) inhibitor,were added into the culture mediums of mesangial cells to do blocking test.Incubated with a final concentration of 3 mg/L defensin α₁,the phosphorylation of extracellular signal regulated kinase (ERK)1/2 and type IV collagen of mesangial cells in different times were evaluated by Western blotting.RESULTS: Defensin α₁ at 3-20 mg/L enhanced proliferation of rat glomerular mesangial cells.The incubation times for the maximum effect on proliferation was 12 h (P<0.01),whereas defensin α₁ concentration >20 mg/L decreased cell proliferation.The cell proliferation induced by defensin α₁ was inhibited by U0126.Stimulation of the cells with defensin α₁ at concentration of 3 mg/L for 5 minutes induced a maximum effect on a ratio of phosphorylation of ERK1/2 to total ERK.After 12 h incubation with defensin α₁,an increase in type IV collagen was observed by Western blotting and continued to increase at 24 h and 48 h (P<0.01).CONCLUSION: Defensin α₁ enhances rat glomerular mesangial cell proliferation and induces type IV collagen production by MAPK signaling pathway.     

Reverse effect of shikonin on epithelial-mesenchymal transition induced by HGF in lung cancer cells

AIM:To investigate the effects of shikonin on the migration, invasion and epithelial-mesenchymal transition (EMT) in human non-small-cell lung cancer PC9 cells induced by hepatocyte growth factor (HGF). METHODS:The effect of shikonin on the viability of PC9 cells was measured by MTT assay. The cell migration and invasion abilities were analyzed by wound healing assay and Transwell method, respectively. The protein expression levels of E-cadherin, N-cadherin and vimentin in the PC9 cells were determined by Western blot. RESULTS:The viability of PC9 cells was significantly inhibited by shikonin in a dose-dependent manner (P<0.01), with IC₅₀ at 9.364 μmol/L. HGF significantly promoted the abilities of migration and invasion, and induced EMT in the PC9 cells. Shikonin significantly inhibited HGF-induced migration and invasion in the PC9 cells. The expression of E-cadherin was significantly down-regulated and the expression of N-cadherin and vimentin was significantly up-regulated in the presence of HGF (50 μg/L). However, shikonin reversed HGF-induced EMT, as indicated by up-regulation of E-cadherin and down-regulation of N-cadherin and vimentin (P<0.01). CONCLUSION:Shikonin reverses HGF-induced EMT in lung cancer PC9 cells.     

Effects of lentivirus-mediated RWDD3 silencing on proliferation and invasion of human glioma U251 cells

AIM: To investigate the effect of RWDD3 gene silencing on the biological characteristics of human glioma U251 cells.METHODS: A lentiviral vector expressing RWDD3 shRNA was constructed and transfeeted into the U251 cells. The expression of RWDD3 at mRNA and protein levels was detected by real-time PCR and Western blot, respectively. The cell activity was determined by MTT assay. The colony formation ability was detected by the colony formation assay. The cell proliferation ability was detected by BrdU incorporation assay. The cell invasion and migration were evaluated by Transwell assay. Flow cytometry was used to monitor the changes of cell cycle distribution and apoptosis.RESULTS: Recombinant lentivirus was successfully transfected into U251 cells. Compared with the cells transfected with the scrambled shRNA and control cells, the cell activity, colony formation ability, and the invasive and migratory activities were inhibited, the cell cycle was arrested in G₀/G₁ phase, and the apoptosis was increased in the U251 cells transfected with RWDD3 shRNA(P<0.05).CONCLUSION: RWDD3 plays a vital role in proliferation and invasion of glioma cells. It may serve as a potential target of gene therapy for glioma.     

p38 MAPK-Pim-3 signal pathway may be involved in cardiomyocyte anoxia preconditioning against anoxia/reoxygenation injury

AIM: To investigate the role of mitogen-activated protein kinases (MAPKs) pathways and the molecular mechanism by which the proto-oncogene Pim-3 protects cardiomyocyte against anoxia/reoxygenation (A/R) injury. METHODS: The primarily cultured neonatal rat ventricular cardiomyocytes were randomly divided into 4 groups: control group; A/R group; APC+A/R group; SB203850, U0126 or SP600125+APC+A/R group. The cells were pre-incubated with U0126 (ERK1/2 inhibitor), SP600125 (SAPK/JNK inhibitor), or SB203850 (p38 MAPK inhibitor) at concentration of 10 μmol/L for 30 min before the APC. The activities of p38 MAPK, JNK and ERK1/2 were detected by Western blotting. The viability of cardiomyocytes was assayed by MTT and the apoptosis of cardiomyocyte was detected by TUNEL. RESULTS: U0126, SB203850, and SP600125 abolished the increased expression of ERK1/2, p38-MAPK, and JNK proteins induced by APC+A/R or A/R, respectively. The expression level of Pim-3 protein significantly decreased when the p38 MAPK signal pathway was inhibited. Meanwhile, the activity of LDH and the apoptosis index increased, and the viability of cardiomyocytes decreased. CONCLUSION: Pim-3 expression through a p38 MAPK signaling pathway may protect cardiomyocytes from A/R injury.     

Effect of toosendanin on invasion and migration of human ovarian cancer cells

AIM: To investigate the effect of toosendanin (TSN) on invasion and migration abilities of human ovarian cancer cells and the related mechanism. METHODS: The human ovarian cancer cell lines CAVO-3 and SKVO-3 were treated with TSN at different concentrations. The cell viabilty at 12, 24, 48, 72 and 96 h after TSN treatment was measured by CCK-8 assay. Scratch wound healing assay and Transwell assay were employed to measure the invasion and migration abilities of CAVO-3 cells. The protein expression of nuclear factor-κB (NF-κB) p65, E-cadherin, N-cadherin, vimentin and Snail was determined by Western blot. RESULTS: TSN significantly inhibited the viability of CAVO-3 and SKVO-3 cells (P<0.05). Compared with control group, the migration and invasion abilities of CAVO-3 cells in TSN group decreased significantly (P<0.05). In addition, the expression of NF-κB p65 and E-cadherin protein increased notably, followed with N-cadherin, vimentin and Snail protein decreased significantly (P<0.05). However, the inhibitor of NF-κB BAY11-7082 reversed the impact above. Compared with TSN group, the migration and invasion abilities in TSN+BAY11-7082 group increased significantly (P<0.05). The protein expression of E-cadherin also decreased notably, followed with the protein expression of N-cadherin, vimentin and Snail increased significantly (P<0.05). CONCLUSION: TSN inhibits the invasion and migration abilities of human ovarian cancer cells, which is related to the inhibition of epithelial-mesenchymal transition process mediated by NF-κB/Snail signaling pathway.     

rhPGRN promotes cell proliferation by regulating autophagy and endoplasmic reticulum stress through MAPK/PI3K pathway

AIM To extract and purify recombinant human progranulin (rhPGRN) and to examine its effect on the proliferation, autophagy and endoplasmic reticulum stress (ERS) in human chondrocyte C28I2 and mouse macrophage RAW264.7. METHODS The histidine-tagged protein was specifically affinity-purified using Ni-NTA Sefinose resin, and the concentration and purity of the target protein were verified by Coomassie blue staining, BCA method and Western blot. The effects of rhPGRN on the proliferation, autophagy and ERS in C28I2 and RAW264.7 cells were detected by cell counting, Western blot and RT-qPCR. RESULTS The highly purified biologically active human recombinant protein rhPGRN was successfully extracted from the cell line with stable PGRN transfection. rhPGRN promoted the proliferation of the C28I2 cells and RAW264.7 cells, up-regulated the mRNA expression of cell cycle-related molecules (PCNA, cyclin B1 and cyclin D1) and the protein expression of Ki67, and increased the phosphorylation levels of proliferation-related signaling molecules ERK and Akt. Treatment with ERK pathway inhibitor U0126 inhibited rhPGRN-promoted proliferation, autophagy and ERS in the cells. The rhPGRN-induced autophagy of the cells was also inhibited by PI3K/Akt pathway inhibitor 3-methyladenine. The rhPGRN-promoted protein expression of Ki67 was down-regulated by autophagy inhibitor bafilomycin A1 and ERS inhibitor 4-phenylbutyric acid. CONCLUSION These results not only established a method for stable extraction of biologically active high-concentration high-purity recombinant protein rhPGRN, but also confirmed that the biological effect of rhPGRN on promoting cell proliferation was achieved through regulating autophagy and ERS via MAPK and PI3K/Akt pathway.     

Effect of hirsutine on hypoxia-induced migration and invasion abilities in human breast cancer MCF-7 cells

AIM: To investigate the effect of hirsutine on hypoxia-induced migration and invasion abilities of human breast cancer MCF-7 cells and its possible mechanism. METHODS: CCK-8 assay was employed to detect the cytotoxic effect of hirsutine on the MCF-7 cells. Cell migration was observed by wound healing assay, and cell invasion ability was measured by Transwell invasion assay. Western blot was used to analyze the protein levels of hypoxia-inducible factor-1α (HIF-1α), Snail, E-cadherin and matrix metalloproteinase-9 (MMP-9). The mRNA levels of HIF-1α was detected by RT-PCR. RESULTS: Hirsutine remarkably reduced the cell viability from 32 μmol/L (P<0.05), and the IC₅₀ value was 62.82 μmol/L. In hypoxia state, MCF-7 cells showed more powerful capabilities of migration and invasion (P<0.05), higher protein levels of HIF-1α, Snail and MMP-9 (P<0.05), lower protein level of E-cadherin (P<0.05), and higher mRNA level of HIF-1α (P<0.05). These hypoxia-induced effects were all inhibited by hirsutine at 16 μmol/L (P<0.05), apart from the mRNA level of HIF-1α. CONCLUSION: Hirsutine inhibits hypoxia-induced migration and invasion in human breast cancer MCF-7 cells most likely via down-regulation of the protein levels of HIF-1α, Snail and MMP-9, and up-regulation of the protein level of E-cadherin.     

Muscarinic receptor 3 agonist promotes epithelial-meschymal transition in human lung cancer A549 cells by activating PI3K/AKT signaling pathway

AIM: To investigate the possible signaling pathway that promotes epithelial-mesenchymal transition (EMT) of the lung cancer A549 cells stimulated with muscarinic receptor 3 (M3R) agonist carbachol. METHODS: The lung cancer cells A549 were treated with 400 μmol/L carbachol. The morphological changes of the cells were observed under inverted phase contrast microscope. The migration and invasion abilites were measured by Wound healing and Transwell assays. qPCR was used to detect the mRNA level of vimentin and E-cadherin. The protein levels of p-AKT, vimentin and E-cadherin were determined by Western blot. RESULTS: After treatment with carbachol, the A549 cells showed loss of the close connection and the cell morphology was transformed from irregular polygon to spindle-like cells. The results of Wound healing and Transwell assays showed that the migration and invasion abilites of the A549 cells were enhanced. Carbachol increased the vimentin expression and decreased the E-cadherin expression at mRNA and protein level (P<0.05). The phosphorylation of AKT in the A549 cells was up-regulated (P<0.05). These changes was inhibited by M3R antagonist 4-DAMP. CONCLUSION: Carbachol promotes EMT in the human lung cancer A549 cells by activating PI3K/AKT signaling pathway.     

The suppressive effects of IFN-α on human gastric carcinoma cell line BGC-823

AIM:To observe the inhibitory effect of interferon-α (IFN-α) on the growth invasiveness and metastasis of human gastric carcinoma cell line BGC-823,and mechanism of its action.METHODS:We detected the influence of IFN-α on the proliferative ability of BGC-823 in cell culture system,the cell vitality with the MTT colorimetric assay,and the cell cycle with flow cytometer (FCM).The regulatory functions of IFN-α to the expression of E-cadherin and matrix metalloproteinase-2 (MMP-2) in tumor cells were estimated by immunohistochemical analysis (S-P).The ultrastructural changes of the junction among the tumor cells were observed under electron microscope.RESULTS:IFN-α can significantly inhibit the growth of human gastric carcinoma cell line BGC-823 in a dose-dependent manner.When the concentration of IFN-α was ≥106 U/L,the cell proliferation can be effectively suppressed，the suppression rate was ≥12.2%,and the blockage appeared at the phase of G1-S of the cell cycle.Under the induction of IFN-α,the expression level of the cell E-cadherin increased while the MMP-2 decreased.The changes on ultrastructure of the cells showed the increased adhesive junctions and the relative compact structure.CONCLUSION:IFN-α can suppress the growth of human gastric carcinoma cell line BGC-823 through its influence on cell cycle.IFN-α can regulate the expression of E-cadherin and MMP-2,make the cell junction closely,so that it has the potential on restricting the invasion and metastasis of gastric carcinoma cells.     

Combination of sorafenib and daunorubicin has antileukemic activity on K562 cells

AIM: To investigate the synergetic inhibitory effect of sorafenib and daunorubicin (DNR) on K562 and U937 cells. METHODS: The inhibitory rate of sorafenib or daunorubicin alone, and the combined inhibitory rate of sorafenib and IC10 daunorubicin were measured by MTT assay. Apoptotic rate of single drug or combination was assessed by flow cytometry (Annexin Ⅴ/PI staining) and Hoechst 33258 staining assay. p-ERK1/2 level was detected by Western blotting after the cells were treated with sorafenib, daunorubicin and U0126 or combinations. Synergistic or antagonistic effect of proliferation and apoptosis on K562 and U937 was estimated according to the Jins Method. RESULTS: Combination of sorafenib and DNR showed synergistic growth inhibition (q>1.15, P<0.01) and synergistic promotion of apoptosis (q>1.15, P<0.05) in K562 and U937 cells. The level of p-ERK1/2 in K562 cells was obviously higher than that in U937 cells (P<0.01). p-ERK1/2 expression was completely inhibited in sorafenib or U0126 treated K562 cells for 24 h. Combination of U0126 with DNR inhibited the proliferation of K562 cells synergistically. CONCLUSION: Combination of sorafenib with DNR showed synergistic cell growth inhibition and promotion of apoptosis in K562 and U937 cells. U937 cells were more sensitive to DNR than K562 cells while K562 cells were more sensitive to sorafenib. Sorafenib enhances the anti-leukemic activity of DNR in K562 and U937 cells via down-regulation of p-ERK1/2 expression.