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Now showing items 81 - 96 of 109

  • Solubilities of 2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane-3,9-dimethanol, alpha,alpha,alpha ',alpha '-tetramethyl-3,9-dioxide in selected solvents

    Fan, Rui-Lan   Wang, Li-Sheng   Guo, Ting-Ting   Wu, Jun-Sheng  

    A phosphorus-containing flame retardant 2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane-3,9-dimethanol, alpha,alpha,alpha',alpha'-tetramethyl-3,9-dioxide (DPDM) was synthesized. The structure and the thermal stability of the compound were characterized by infrared spectroscopy (IR), nuclear magnetic resonance (H-1 NMR), mass spectroscopy (MS), elemental analysis, and thermogravimetric analysis. Using a static analytical method, the solubilities of DPDM in acetic acid + acetone binary mixtures, water, methanol, and ethanol were determined in the temperature range from (293.14 to 338.14) K. The solubility data were correlated with an empirical equation.
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  • Shp-2 tyrosine phosphatase is required for hepatocyte growth factor-induced activation of sphingosine kinase and migration in embryonic fibroblasts.

    Duan, Hai-Feng   Qu, Cheng-Kui   Zhang, Qun-Wei   Yu, Wen-Mei   Wang, Hong   Wu, Chu-Tse   Wang, Li-Sheng  

    Shp-2, a ubiquitously expressed protein tyrosine phosphatase containing two Src homology 2 domains, plays an important role in integrating signaling from the cell surface receptors to intracellular signaling mechanisms. Previous studies have demonstrated that the Shp-2 is involved in hepatocyte growth factor (HGF)-induced cell scattering. Here we report that Shp-2 is required for the HGF-induced activation of sphingosine kinase-1 (SPK1), a highly conserved lipid kinase that plays an important role in cell migration. Loss-of-function mutation of Shp-2 did not affect the expression of SPK1, but resulted in its inactivation and the blockage of HGF-induced migration in embryonic fibroblasts. Reintroduction of functional wild type (WT) Shp-2 into the mutant cells partially restored SPK1 activation, and overexpression of SPK1 in these mutant cells enhanced HGF-induced cell migration. Inhibition of expression or activity of SPK1 in WT cells markedly decreased intracellular S1P levels and HGF-induced cell migration. Furthermore, we found that Shp-2 co-immunoprecipitated with SPK1 and c-Met in embryonic fibroblasts. These studies suggest that Shp-2 is an SPK1-interacting protein and that it plays an indispensable role in HGF-induced SPK1 activation.
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  • Intercellular adhesion molecule-1 inhibits osteogenic differentiation of mesenchymal stem cells and impairs bio-scaffold-mediated bone regeneration in vivo.

    Xu, Fen-Fen   Zhu, Heng   Li, Xi-Mei   Yang, Fei   Chen, Ji-De   Tang, Bo   Sun, Hong-Guang   Chu, Ya-Nan   Zheng, Rong-Xiu   Liu, Yuan-Lin   Wang, Li-Sheng   Zhang, Yi  

    Mesenchymal stem cell (MSC) loaded bio-scaffold transplantation is a promising therapeutic approach for bone regeneration and repair. However, growing evidence shows that pro-inflammatory mediators from injured tissues suppress osteogenic differentiation and impair bone formation. To improve MSC-based bone regeneration, it is important to understand the mechanism of inflammation mediated osteogenic suppression. In the present study, we found that synovial fluid from rheumatoid arthritis patients and pro-inflammatory cytokines including interleukin-1alpha, interleukin-1beta, and tumor necrosis factor alpha, stimulated intercellular adhesion molecule-1(ICAM-1) expression and impaired osteogenic differentiation of MSCs. Interestingly, overexpression of ICAM-1 in MSCs using a genetic approach also inhibited osteogenesis. In contrast, ICAM-1 knockdown significantly reversed the osteogenic suppression. In addition, after transplanting a traceable MSC-poly(lactic-co-glycolic acid) construct in rat calvarial defects, we found that ICAM-1 suppressed MSC osteogenic differentiation and matrix mineralization in vivo. Mechanistically, we found that ICAM-1 enhances MSC proliferation but causes stem cell marker loss. Furthermore, overexpression of ICAM-1 stably activated the MAPK and NF-kappaB pathways but suppressed the PI3K/AKT pathway in MSCs. More importantly, specific inhibition of the ERK/MAPK and NF-kappaB pathways or activation of the PI3K/AKT pathway partially rescued osteogenic differentiation, while inhibition of the p38/MAPK and PI3K/AKT pathway caused more serious osteogenic suppression. In summary, our findings reveal a novel function of ICAM-1 in osteogenesis and suggest a new molecular target to improve bone regeneration and repair in inflammatory microenvironments. =20
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  • Measurement and Correlation of Solubility of Resorcinol Bis(cyclic 2,2-dimethyl-1,3-propanediol phosphate) in Selected Solvents from T=3D293.15 to 333.15 K

    Zhao, Dong-Fang   Wang, Li-Sheng   Sun, Jian   Chen, Chuan-Ming  

    A phosphorus flame retardant named resorcinol bis(cyclic 2,2-dimethyl-1,3-propanediol phosphate) (RCDMPP) was synthesized and characterized by high-performance liquid chromatography (HPLC), elemental analysis (EA), Fourier transform infrared spectroscopy (FTIR), mass spectra (MS), and nuclear magnetic resonance (NMR). Its thermal stability was evaluated via thermogravimetric analysis (TGA), and the fusion enthalpy and melting point of RCDMPP were detected by differential scanning calorimetry (DSC). The solubilities of RCDMPP in selected solvents at T =3D 293.15 to 333.15 K and atmospheric pressure were measured via a static-analytic method. The solubility data were correlated with modified Apelblat, Scatchard-Hildebrand, Buchowski-Ksiazczak (lambda h), nonrandom two liquid (NRTL), Wilson, and universal quasichemical (UNIQUAC) equations. The calculated results obtained from these models showed good agreement with the experimental data, and the NRTL, Wilson, and UNIQUAC models give better correlation results compared with modified Apelblat and lambda h models. The solubility parameter of RCDMPP was calculated by use of the Scatchard-Hildebrand methodology.
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  • The protein kinase C agonist prostratin induces differentiation of human myeloid leukemia cells and enhances cellular differentiation by chemotherapeutic agents

    Shen, Xing   Xiong, Guo-Lin   Jing, Yu   Xiao, He   Cui, Yu   Zhang, Yan-Feng   Shan, Ya-Jun   Xing, Shuang   Yang, Meng   Liu, Xiao-Lan   Dong, Bo   Wang, Li-Sheng   Luo, Qing-Liang   Yu, Zu-Yin   Cong, Yu-Wen  

    As acute myeloid leukemia (AML) cells are characterized by uncontrolled self-renewal and impaired cellular differentiation, induction of terminal differentiation of leukemia cells by differentiating agents has been proposed as an attractive therapeutic strategy to treat AML Here, we demonstrated that prostratin, a potent protein kinase C (PKC) activator, inhibited the growth of myeloid leukemia cells by a predominant G1 arrest with variable induction of apoptosis. Conversely, prostrafin induced significant differentiation of AML cell lines and primary AML blasts as evidenced by morphology and immunophenotyping. The effects of prostratin were PKC dependent, and activation of mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK) kinase (MEK) 1/2 by PKC was required for prostratin-induced cell differentiation. Consequently, prostratin reprogrammed transcriptional factor expression, and ectopic expression of c-Myc in HL-60 cells significantly eliminated prostratin-mediated cellular differentiation and cell cycle arrest, indicating an essential role for c-Myc suppression in the differentiation-inducing effects of prostratin. Finally, prostratin was able to potentiate cellular differentiation induced by chemotherapeutic agents such as Ara-C. Together, we proposed that prostratin alone or administered with other anticancer agents may be effective in differentiation therapy of AML. (C) 2014 Elsevier Ireland Ltd. All rights reserved.
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  • Endocrine glands-derived vascular endothelial growth factor protects pancreatic cancer cells from apoptosis via upregulation of the myeloid cell leukemia-1 protein

    Ren, Li-Nan   Li, Qing-Fang   Xiao, Feng-Jun   Yan, Jun   Yang, Yue-Feng   Wang, Li-Sheng   Guo, Xiao-Zhong   Wang, Hua  

    Endocrine glands-derived vascular endothelial growth factor (EG-VEGF, also termed as Prok1)-a novel cytokine that selectively acts on the endothelial cells of endocrine glands-was recently reported to be involved in the regulation Of tumor cell growth and Survival. However, its roles in the regulation of pancreatic cancer progression remain unclear. In this report, we investigated the suppressive effects of EG-VEGF on pancreatic cancer cell apoptosis and the relevant mechanisms. By using reverse-transcriptase polymerase chain reaction (RT-PCR) we found that the Mia PaCa II cells of the pancreatic cancer cell line express the mRNAs of both EG-VEGF (Prok1) and its receptors. EG-VEGF protects pancreatic cancer cells from apoptosis through upregulation of myeloid cell leukemia-1 (Mcl-1), an anti-apoptotic protein of the bcl-2 family. Treatment of pancreatic cancer cells with EG-VEGF results in the rapid phosphorylation of mitogen-activated protein kinase (MAPK), STAT3, and AKT, which are involved in the Upregulation of Mcl-1 expression. EG-VEGF (Prok1) protects Mia PaCa II cells from apoptosis through G protein-coupled receptor (GPR)-induced activation of multiple signal pathways, and hence can be a novel target for pancreatic cancer therapy. (C) 2009 Elsevier Inc. All rights reserved.
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  • Activity coefficients at infinite dilution of alkanes, alkenes, and alkyl benzenes in 1-propyl-2,3-dimethylimidazolium tetrafluoroborate using gas-liquid chromatography

    Wang, Ming-Hui   Wu, Jun-Sheng   Wang, Li-Sheng   Li, Mi-Yi  

    Activity coefficients at infinite dilution, gamma(infinity)(i), have been determined for 17 organic solutes, alkanes, alkenes, and alkyl benzenes, in the ionic liquid 1-propyl-2,3-dimethylimidazolium tetrafluoroborate ([PDMIM][BF4]) by the gas-liquid chromatographic method with the ionic liquid as the stationary phase. The measurements were carried out in the temperature range of 303.15 K to 363.15 K. The partial molar excess enthalpies at infinite dilution, H-i(E,infinity), were also determined for the solutes from the temperature dependence of the gamma(infinity)(i) values.
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  • S-H Bond Activation in H2S and Thiols by[RhMn(CO)4(Ph2PCH2PPh2)2]. Compounds Containing Terminal or Bridging Sulfhydryl and Thiolato Groups

    Wang, Li-Sheng   McDonald, Robert   Cowie, Martin  

    The complex [RhMn(CO)4(dppm)2] (dppm = Ph2PCH2PPh2) reacts with H2S and thiols to yield the products [RhMn(SR)(CO)3(mu-H)(dppm)2] (R = H, Et, Ph), containing terminal sulfhydryl or thiolato groups bound to Rh and a bridging hydride ligand. The sulfhydryl species loses H-2 over the period of several days and scavenges CO to yield [RhMn(CO)4(mu-S)(dppm)2]. This sulfide-bridged product can be protonated or alkylated to give the cationic species [RhMn(CO)4(mu-SR)(dppm)2]+ (R = H, CH3, CH2SiMe3), containing bridging sulfhydryl or thiolato groups. The bridging sulfhydryl group in [RhMn(CO)4(mu-SH)(dppm)2]+ Undergoes a Michael-type addition to alkynes to yield [RhMn(CO)4(mu-SC(R) = C(H)R')(dppm)2]+ (R = H, R'= C(O)Me; R = R'= CO2Me) in which the unsaturated thiolato group bridges the metals. With hexafluoro-2-butyne, an analogous reaction occurs to yield the related species [RhMn(SC(CF3) = C(H)CF3)(CO)4(dppm)2]+, but in this case the thiolato group is terminally bound to Rh. The structure of [RhMn(CO)4(mu-S)(dppm)2] has been determined by X-ray crystallography. This compound crystallizes in the monoclinic space group P2(1)/n, with a = 12.419(4) angstrom, b = 25.735(2) angstrom, c = 16.464(2) angstrom, beta = 97.70(2)-degrees, V = 5215(3) angstrom, and Z = 4, and has refined to R = 0.055 and R(W) = 0.071 on the basis of 5865 unique observations and 598 parameters varied. This compound shows a semibridging carbonyl group which is primarily bound to Mn (Mn-C(2) = 1.959(5) angstrom, Rh-C(2) = 2.214(5) angstrom), in line with the small Rh-C coupling of 8 Hz observed in the C-13 NMR for this carbonyl.
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  • Activity coefficients at infinite dilution of alkanes, alkenes, and alkyl benzenes in 1-hexyl-3-methylimidazolium trifluoromethanesulfonate using gas-liquid chromatography

    Yang, Xiao-Jun   Wu, Jun-Sheng   Ge, Ming-Lan   Wang, Li-Sheng   Li, Mi-Yi  

    Activity coefficients at infinite dilution gamma(infinity)(i) have been determined for 17 organic solutes, alkanes, alkenes, and alkyl benzenes, in the ionic liquid 1-hexyl-3-methylimidazolium trifluoromethanesulfonate ([HMIM][CF3SO3]) by the gas-liquid chromatographic (GLC) method with the ionic liquid as the stationary phase. The measurements were carried out in the temperature range of (303.15 to 363.15) K. The partial molar excess enthalpies at infinite dilution H-i(E,infinity) were also determined for the solutes from the temperature dependence of the gamma(infinity)(i) values.
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  • Activity Coefficients at Infinite Dilution of Alkanes, Alkenes, and Alkyl Benzenes in 1-(2-Hydroxyethyl)-3-methylimidazolium Tetrafluoroborate Using Gas-Liquid Chromatography

    Zhang, Ya   Wang, Li-Sheng   Li, Yi  

    Activity coefficients at infinite dilution of 14 organic solutes, alkanes, alkenes, and alkyl benzenes, in 1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate, have been determined using gas-liquid chromatography over a temperature range of (303.15 to 363.15) K with the ionic liquid as the stationary phase. The partial molar excess enthalpies at infinite dilution were also determined for the solutes from the temperature dependence of the experimental activity values.
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  • Bortezomib and sphingosine kinase inhibitor interact synergistically to induces apoptosis in BCR/ABl(+) cells sensitive and resistant to STI571 through down-regulation Mcl-1

    Li, Qing-Fang   Yan, Jun   Zhang, Kai   Yang, Yue-Feng   Xiao, Feng-Jun   Wu, Chu-Tse   Wang, Hua   Wang, Li-Sheng  

    Interactions between the proteasome inhibitor, bortezomib, and the sphingosine kinase (SPK1) inhibitor, SKI, were examined in BCR/ABL human leukemia cells. Coexposure of K562 or chronic myeloid leukemia (CML) cells from patients to subtoxic concentrations of SKI (10 mu M) and bortezomib (100 nM) resulted in a synergistic increase in caspase-3 cleavage and apoptosis. These events were associated with the downregulation of BCR-ABL and Mcl-1, and a marked reduction in SPK1 expression. In imatinib mesylate-resistant K562 cells that displayed decreased BCR-ABL expression, bortezomib/SKI treatment markedly increased apoptosis and inhibited colony-formation in association with the downregulation of Mcl-1. Finally, the bortezomib/SKI regimen also potently induced the downregulation of BCR/ABL and Mcl-1 in human leukemia cells. Collectively, these findings suggest that combining SKI and bortezomib may represent a novel strategy in leukemia, including apoptosis-resistant BCR-ABL(+) hematologic malignancies. (c) 2010 Elsevier Inc. All rights reserved.
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  • Cyclopentadienylmolybdenum(II) and -(III) Complexes Containing Diene and Allyl Ligands. 1. Isomeric Preferences and Isomerization Rates in a Pair of Redox-Related Organometallic Complexes

    Wang, Li-Sheng   Fettinger, James C.   Poli, Rinaldo  

    Treatment of CpMoCl2(eta-C4H6) (1) with 1 equiv of allylmagnesium bromide yields the dinuclear complexes [CPMo(eta-C4H6)(mu-Br)](2) (2, major) and Cp2Mo2(eta-C4H6)(2)(mu-Br)(mu-Cl) (3, minor). A solid solution of compounds 2 and 3 adopts an anti geometry in the solid state, as shown by X-ray crystallography, whereas both anti and syn isomers are observed in benzene solution by H-1-NMR spectroscopy. The reaction of 1 with 2 equiv of allylmagnesium bromide yields [CpMo(eta-C3H5)(eta-C4H6)] as an equilibrium mixture of a major (98%, 4a) and a minor (2%, 4b) isomer. NOE-NMR studies indicate the CpMo(prone-C3H5)(supine-C4H6) orientation for the major isomer 4a, which is also found in the solid state by X-ray crystallography. The orientation of 4b is suggested by the 'H-NMR chemical shifts as CpMo(supine-C3H5)(supine-C4H6). Oxidation of 4a/b by ferrocenium hexafluorophosphate in dichloromethane gives the 17-electron compounds [CpMo(eta-C3H5)(eta-C4H6)][PF6] (5a/b). The green compound 5a converts into the more stable red-violet 5b with an estimated half-life of <20 s in THF. It can be observed, however at low temperature by EPR spectroscopy. The [CpMo(supine-eta-C3H5)(supine-eta-C4H6)][PF6] configuration for 5b has been confirmed by X-ray diffraction methods. Upon reduction with cobaltocene, 5b is converted selectively to 4b, followed by slow equilibration (t(1/2) = 6.5 h) with 4a. Refluxing or photolyzing a solution of 4a/b in benzene generates a third isomer, 4c, which adopts a CpMo(supine-C3K5)(s-trans-C4H6) configuration as confirmed by an X-ray analysis. The distribution of 4a and 4c at equilibrium is approximately 1:1 by starting either from 4a/b or from pure 4c and independent of the equilibration method (thermal/photochemical). Oxidation of 4c generates the corresponding 1-electron oxidation product 5c, which rapidly isomerizes to 5b. It can be observed, however, by EPR in THF together with a fourth isomer, 5d (ca. 1:1), believed to differ from 5c only in the orientation of the allyl ligand. Equilibrium, rate, and electrochemical data allow most of the thermodynamic and kinetic parameters related to the transformation of the different compounds to be sorted out. The faster s-trans- to s-cis-butadiene isomerization for 5 relative to 4 indicates the easier accessibility of the unsaturated 15-electron vs 16-electron intermediate. Possible reasons for this trend are analyzed.
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  • Development of a Universal Group Contribution Equation of State. 4. Prediction of Vapor?Liquid Equilibria of Polymer Solutions with the Volume Translated Group Contribution Equation of State

    Wang, Li-Sheng   Ahlers, Jens   Gmehling, Jürgen  

    The simplified mixing rule for the Peng-Robinson EOS parameters proposed by Ahlers and Gmehling has been extended to calculate the VLE behavior of polymer solutions. To avoid the calculation of the molar volumes in the mixing rule as required in the UNIFAC-FV model, the quadratic mixing rule for parameter b has been modified to take into account the free volume contribution to the excess Gibbs energy for the solvent-polymer solutions. The group interaction parameters and relative van der Waals surface area parameters of the original UNIFAC model are used for the calculations. Satisfactory predictions are obtained for 18 solvent-polymer systems, which cover a wide range of molar mass of the polymers. Additionally, activity coefficients at infinite dilution based on weight fraction for 36 systems have been calculated. The results of this paper show that the presented mixing rule results in a simple, predictive model with satisfying accuracy for the application in industrial process design.
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  • Catalytic Epoxidation of a Technical Mixture of Methyl Oleate and Methyl Linoleate in Ionic Liquids Using MoO(O(2))(2)center dot 2QOH (QOH=8-quinilinol) as Catalyst and NaHCO(3) as co-Catalyst

    Cai, Shuang-Fei   Wang, Li-Sheng   Fan, Chuan-Lei  

    The oxo-diperoxo molybdenum(VI) complex MoO(O(2))(2)center dot 2QOH (QOH = 8-quinilinol) was prepared and characterized by elemental analysis, IR and UV-Vis spectra. The ionic liquids (ILs) [bmim][BF(4)], [hydemim][BF(4)], and [bmim][PF(6)] were characterized by (1)H-NMR and UV-Vis spectra. The epoxidation of a technical mixture of methyl oleate and methyl linoleate with H(2)O(2), in [bmim][BF(4)], [hydemim][BF(4)] and [bmim][PF(6)], catalyzed by MoO(O(2))(2)center dot 2QOH (QOH = 8-quinilinol) and with NaHCO(3) as co-catalyst has been studied for the first time. It was found that high conversions of methyl oleate and methyl linoleate to their respective oxidation products, as well as the total selectivity of their oxidation products to oxirane in [hydemim][BF(4)] were obtained. Also, the IL phases containing the Mo(VI) catalyst can be readily recycled by washing with diethyl ether and drying, and the Mo(VI) catalyst can be reused at least five times.
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  • Plasma-Nitrided Ga2O3(Gd2O3) as Interfacial Passivation Layer for InGaAs Metal–Oxide– Semiconductor Capacitor With HfTiON Gate Dielectric

    Wang, Li-Sheng   Xu, Jing-Ping   Liu, Lu   Lu, Han-Han   Lai, Pui-To   Tang, Wing-Man  

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  • Induction of apoptotic DNA fragmentation mediated by mitochondrial pathway with caspase-3-dependent BID cleavage in human gastric cancer cells by a new nitroxyl spin-labeled derivative of podophyllotoxin

    Yang, Yu-Jie   Qi, She-Ning   Shi, Rui-Yue   Yao, Jun   Wang, Li-Sheng   Yuan, Hu-Qin   Jing, Yuan-Xue  

    Purpose: 4-[4"-(2", 2", 6", 6"-tetramethyl-l"-piperidinyloxy) amino]-4'-demethyl-epipodophyllotoxin (GP7) is a new semi-synthesized nitroxyl spin-labeled derivative of podophyllotoxin with anti-lukemic and anti-osteosarcoma effects. The purpose of the present study is to investigate the anti-gastric cancer (GC) effects of GP7 and the possible involvement of caspase pathway in GP7-induced apoptotic DNA fragmentation in human GC cells. Materials and methods: Effects of GP7 on the proliferation of human GC cell lines MKN28, AGS, BGC-823 and HGC-27 in different degrees of differentiation and normal human gastric epithelial cell line GES-1 were studied by MTT assay and compared with the effects of etoposide. Effects of GP7 on cell viability and heat shock protein 90 expression of BGC-823 and HGC-27 cells were analyzed by trypan blue exclusion test and western blotting, respectively. Effects of GP7 on apoptotic DNA fragmentation and caspase pathway of BGC-823 and HGC-27 cells were detected by agarose gel electrophoresis, colorimetric assay and western blotting. Caspase-3 inhibitor was used to manipulate the activity of caspase-3. Results: GP7 inhibited concentration-and time-dependently the proliferation of human GC cells, and the inhibitory effect of GP7 on the proliferation of BGC-823 or HGC-27 cells was 1.15- or 1.21-fold higher than that of etoposide. GP7 downregulated heat shock protein 90, improved the anti-GC effects of adriamycin, cisplatin, 5-fluorouracil and their combinations, induced apoptotic DNA fragmentation, activations of caspase-9 and -3 but not -8, cytochrome-c release and BID cleavage in BGC-823 and HGC-27 cells. Caspase-3 inhibitor abrogated GP7-induced BID cleavage, decreased cytochrome-c release, caspase-9 and -3 activities and apoptotic DNA fragmentation but increased cell viability in BGC-823 and HGC-27 cells. Conclusion: Our findings indicate that GP7 is a promising anti-GC derivative of podophyllotoxin, and GP7-induced apoptosis in human GC cells may be mediated by mitochondrial pathway with caspase-3dependent BID cleavage. (C) 2017 Elsevier Masson SAS. All rights reserved.
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