MAPK信号通路对地塞米松抑制Jurkat细胞增殖及诱导凋亡的影响

目的研究丝裂原活化蛋白激酶(MAPK)信号通路对地塞米松(Dexamethasone,DEX)诱导急性淋巴细胞白血病Jurkat细胞凋亡及抑制细胞增殖的影响。方法观察地塞米松、PD98059、SP600125、SB203580及地塞米松分别联合PD98059、SP600125、SB203580对Jurkat细胞增殖及凋亡的抑制作用。以急性淋巴细胞白血病Jurkat细胞为研究对象,应用WST-1法检测细胞的增殖活力;流式细胞术分析细胞凋亡。结果地塞米松对Jurkat细胞24 h和48 h抑制细胞增殖50%的药物浓度(IC50)分别为829、335μM。100μM以上地塞米松以时间、剂量依赖方式抑制Jurkat细胞增殖;地塞米松分别联合PD98059、SP600125可增加对Jurkat细胞增殖的抑制效应,联合SB203580对地塞米松抑制Jurkat细胞增殖无影响。10μM地塞米松联合20μM PD98059可显著增加地塞米松诱导Jurkat细胞凋亡的作用,细胞凋亡率由8.5%升至28.4%。结论急性淋巴细胞白血病Jurkat细胞为糖皮质激素耐药细胞。阻断p38MAPK对地塞米松抑制Jurkat细胞增殖无明显影响。阻断ERK、JNK信号通路均可增强地塞米松对Jurkat细胞的杀伤作用,达到逆转Jurkat细胞对地塞米松的耐药。急性淋巴细胞白血病Jurkat细胞糖皮质激素耐药可能与ERK、JNK通路的活化有关。     

MAPK信号通路对蟾蜍灵抑制Jurkat细胞增殖及诱导其凋亡的影响

目的研究丝裂原活化蛋白激酶(MAPK)信号通路对蟾蜍灵(Bufalin)抑制急性淋巴细胞白血病Jurkat细胞增殖及诱导细胞凋亡的影响,初步探讨MAPK在蟾蜍灵治疗急性淋巴细胞白血病中的作用。方法WST-1法检测细胞的增殖活力,流式细胞术分析细胞凋亡。结果蟾蜍灵作用Jurkat细胞48 h,抑制细胞增殖50%的药物浓度(IC50)为44 nmol/L;5 nmol/L及以上蟾蜍灵以剂量依赖方式抑制Jurkat细胞增殖;20 nmol/L蟾蜍灵分别联合PD98059、SP600125,可显著增加对Jurkat细胞增殖的抑制,促进细胞凋亡;20 nmol/L蟾蜍灵联合SB203580作用于Jurkat细胞,可显著减少对Jurkat细胞增殖的抑制但对其凋亡无显著影响。结论 MAPK信号通路与蟾蜍灵抑制急性淋巴白血病Jurkat细胞增殖及诱导凋亡有相关性,表现为ERK和JNK促进增殖、抑制细胞凋亡;p38MAPK抑制增殖,但对凋亡无明显影响。     

铜绿假单胞菌通过MAPK信号传导通路诱导U937细胞表达IL-8

目的探讨铜绿假单胞菌(PA)活菌对不同分化状态的U937细胞表达IL-8的诱导作用及通过MAPK信号传导通路的调控机制。方法应用人单核白血病细胞系-U937细胞,采用ELISA和RT-PCR法对PA诱导不同分化状态的U937细胞IL-8蛋白分泌和其mRNA表达进行研究,并观察MAPKs抑制剂PD98059和SB203580对IL-8表达的影响。结果PA可促进U937细胞及PMA分化的U937细胞IL-8的mRNA及蛋白分泌,而且具有明显的量效和时效关系。分别用SB203580抑制p38MAPK通路、用PD98059抑制ERK通路,均能引起抑制剂浓度依赖的IL-8的表达(P<0.01)。结论PA以浓度和时间依赖的方式感染U937细胞,促进IL-8的分泌和mRNA表达,PA可能通过MAPK信号通路启动IL-8的高效表达和分泌。     

丝裂原活化蛋白激酶通路对慢支大鼠肺泡巨噬细胞产生TNF-α的影响及枇杷叶三萜酸的作用机制

目的探究丝裂原活化蛋白激酶(MAPK)信号转导通路对慢性支气管炎(CB)大鼠肺泡巨噬细胞(AM)中肿瘤坏死因子α(TNF-α)生成的影响及枇杷叶三萜酸(TAL)的作用环节。为TAL治疗慢支的抗炎作用机制提供进一步的实验依据。方法以AM为实验平台分别给予MAPK 3条通路(ERK,p38,JNK)的特异性阻滞剂,用RT-PCR和Westernblot的方法来分别检测CB大鼠AM中TNF-α的mRNA及蛋白的表达水平。并采用析因实验设计,ELISA法检测AM培养上清中的TNF-α的水平。结果RT-PCR和Western blot的结果均显示ERK特异性阻滞剂(PD98059)和p38特异性阻滞剂(SB203580)对CB大鼠AM中TNF-α的表达有明显的抑制作用。析因分析结果表明TAL、特异性阻滞剂(PD98059和SB203580)及其交互作用项对TNF-α含量的影响存在统计学意义。结论TAL对TNF-α的抑制作用可能与其作用于ERK和p38通路有关,这可能是TAL治疗与防治慢支的主要作用环节之一。     

鸢尾苷元对血管紧张素Ⅱ作用下心肌成纤维细胞增殖和凋亡的影响

目的探讨鸢尾苷元对血管紧张素Ⅱ(AngⅡ)作用下心肌成纤维细胞增殖和凋亡的影响及其机制。方法采用差速贴壁法获得纯化的大鼠心肌成纤维细胞,采用MTT法和原位末端标记法检测鸢尾苷元或磷脂肌醇-3-激酶(PI3K)/蛋白激酶B(Akt)信号通路对AngⅡ作用下心肌成纤维细胞增殖和凋亡的影响,采用RT-PCR检测鸢尾苷元对AngⅡ作用下心肌成纤维细胞中凋亡相关基因Bcl-2、Bax mRNA表达的影响,Western blot法检测鸢尾苷元对AngⅡ作用下心肌成纤维细胞中凋亡相关蛋白Bcl-2、Bax和PI3K/Akt信号通路相关蛋白p-Akt、T-Akt表达的影响。结果AngⅡ能明显促进心肌成纤维细胞增殖,抑制细胞凋亡;给予50,100和200μmol·L^-1鸢尾苷元后,AngⅡ使心肌成纤维细胞促增殖和抑凋亡作用明显受到抑制,且200μmol·L^-1鸢尾苷元作用最显著。200μmol·L^-1鸢尾苷元能够明显抑制AngⅡ诱导的Bcl-2 mRNA和p-Akt、Bcl-2蛋白的表达;减弱AngⅡ对Bcl-2 mRNA和蛋白表达的抑制作用,不影响T-Akt蛋白表达。PI3K/Akt信号通路抑制剂LY294002作用后,AngⅡ使心肌成纤维细胞的促增殖和抑凋亡作用明显受到抑制;而给予PI3K/Akt信号通路激活剂HY-N1412作用后,AngⅡ对心肌成纤维细胞的促增殖和抑凋亡作用明显得到促进,HY-N1412能明显逆转鸢尾苷元对AngⅡ刺激下的心肌成纤维细胞抑增殖和促凋亡作用。结论鸢尾苷元可通过PI3K/Akt信号通路减弱AngⅡ对心肌成纤维细胞促增殖和抑凋亡作用。     

M受体对H_2O_2诱导PC12细胞凋亡的保护作用及机制

目的研究毒蕈碱型胆碱受体在抗氧化应激所诱导的凋亡中不同亚型之间是否存在差异。方法用含有M1M4毒蕈碱型胆碱受体亚型的质粒pCDNA3.0转染PC12细胞,加入过氧化氢诱导凋亡,观察氨甲酰胆碱激动毒蕈碱型胆碱受体后各亚型之间抗凋亡能力是否存在差异,同时应用毒蕈碱型胆碱受体抑制剂阿托品,ERK和PI3K信号通路抑制剂PD98059与LY294002观察参与保护作用的相关的信号通路。结果氨甲酰胆碱激动毒蕈碱型胆碱受体后产生抗凋亡效应,各亚型之间没有差异,PI3K信号通路参与了保护作用。结论M1M4亚型毒蕈碱型胆碱受体在对抗过氧化氢诱导的凋亡没有亚型之间的差异,PI3K信号通路参与了保护作用。     

PI3K信号通路在LPS诱导RAW264.7细胞表达sTREM-1中的作用

目的：探讨磷脂酰肌醇3-激酶(PI3K)信号通路在脂多糖(LPS)诱导RAW264.7细胞表达可溶性髓样细胞触发受体-1(sTREM-1)中的作用。方法培养小鼠巨噬细胞株RAW264.7,采用相同浓度的LPS在不同时间诱导RAW264.7细胞,应用Western blot法分别检测PI3K蛋白表达水平,RT-PCR法检测PI3K mRNA表达水平,酶联免疫吸附(ELISA)法检测细胞培养血清中sTREM-1表达水平。用不同浓度PI3K特异性抑制剂LY294002处理细胞,观察上述指标变化。结果 LPS可时间依赖性地诱导RAW264.7细胞PI3K蛋白、PI3K mRNA的表达;LY294002可浓度依赖性地抑制PI3K蛋白、PI3K mRNA的表达;LY294002阻断PI3K信号转导通路后,LPS对sTREM-1表达的诱导作用受到显著抑制,并且具有剂量依赖性。结论 LPS通过PI3K信号通路诱导RAW264.7细胞表达sTREM-1。     

PI3K/Akt信号通路抑制剂对人胃癌细胞增殖及相关基因表达的影响

目的 研究磷脂酰肌醇-3-激酶/蛋白激酶B(PI3K/Akt)信号通路抑制剂渥曼青霉素对人胃癌细胞增殖、细胞周期与凋亡的影响以及相关基因蛋白激酶B(pAkt)、磷酸化腺苷酸活化蛋白激酶(pAMPK)、S期激酶相关蛋白2(Skp2)及P27kip1蛋白表达的影响.方法 分别用不同浓度渥曼青霉素处理处于对数生长阶段的BGC823细胞12、24、48 h,利用MTT实验检测其对胃癌细胞增殖的影响,胃癌细胞凋亡及细胞周期的检测采用流式细胞术,Western-blotting检测p-Akt、p-AMPK、Skp2及P27kip1蛋白的表达变化.结果 渥曼青霉素可明显抑制BGC823细胞的增殖,在一定范围内具有时间和浓度依赖性.20 mmol/L渥曼青霉素作用细胞24 h时,细胞生长周期阻滞于G0/G1期,细胞凋亡率为(44.44±3.17)％;Western blot检测显示,pAkt、pAMPK及Skp2蛋白表达随着药物浓度的增加而减少,P27kip1蛋白表达随着药物浓度增加而增加.结论 PI3K/Akt信号通路抑制剂渥曼青霉素能够明显下调胃癌细胞的增殖活性,导致胃癌细胞周期被阻滞于G0/G1期并诱导细胞发生凋亡,进一步研究证实PI3K/Akt信号通路介导的Skp2及P27kip1蛋白调控在凋亡过程中发挥重要作用.     

知母皂苷对Aβ_(25-35)引起的巨噬细胞炎症介质释放的抑制作用及信号转导机制

目的观察知母皂苷(SAaB)是否能对抗淀粉样β蛋白片段25-35(Aβ25-35)引起的巨噬细胞炎症介质释放并探讨其信号转导通路的影响。方法小鼠腹腔巨噬细胞培养24 h,加入不同浓度SAaB(10、30和100μmol·L-1)或加入不同的阻断剂(诱导性一氧化氮合酶阻断剂SMT、MEK1的特异性阻断剂PD98059、p38MAPK特异性阻断剂SB203580和PI3K特异性阻断剂LY294002),之后加入Aβ25-35(20μmol·L-1)继续培养。Aβ25-35作用2 h后,采用Westernblot观察巨噬细胞磷酸化Akt/PKB蛋白表达水平的改变。Aβ25-35作用48 h后,取巨噬细胞培养上清液分别测定肿瘤坏死因子-α(TNF-α)和一氧化氮(NO)的含量变化。结果 PD98059和LY294002均可明显抑制Aβ25-35引起的巨噬细胞TNF-α产生增加和磷酸化Akt/PKB表达明显增加。SMT可完全对抗Aβ25-35引起的NO释放增加。SAaB可明显抑制Aβ25-35引起的TNF-a和NO的产生增加,并呈明显的浓度依赖性。SAaB也可明显抑制Aβ25-35引起磷酸化Akt/PKB表达增加。结论 SAaB能够明显的抑制Aβ25-35引起的巨噬细胞炎症因子释放,这种抑制作用部分通过SAaB抑制Akt/PKB信号转导通路产生。     

胍丁胺对体外培养海马神经前体细胞增殖的影响及作用机制

目的前期证明胍丁胺(agmatine,Agm)作为一种新型神经递质具有抗抑郁作用,能够促进慢性应激小鼠海马神经元再生。本实验通过观察胍丁胺对体外培养海马神经前体细胞增殖的影响及作用机制,探讨其抗抑郁作用的细胞分子机制。方法培养扩增新生大鼠海马神经前体细胞,通过3H-TdR参入法和CCK-8试剂盒检测胍丁胺对其增殖的影响;培养体系内加入H89(PKA特异性抑制剂)或PD98059(MEK特异性抑制剂),观察这两种抑制剂对胍丁胺作用的影响。结果胍丁胺在0.1~10μmol·L-1浓度范围内,浓度依赖性地促进神经前体细胞的增殖,这种促增殖作用可以被H89(10μmol·L-1)和PD98059(10μmol·L-1)取消。结论胍丁胺可以促进体外培养的海马神经前体细胞增殖,此作用与cAMP-PKA-CREB通路和MEK-ERK-CREB通路相关。     

Fluorofenidone inhibits transforming growth factor-beta1-induced cardiac myofibroblast differentiation

Cardiac myofibroblast differentiation, characterized by expression of alpha-smooth muscle actin (alpha-SMA) and fibrillar collagens, plays a key role in the adverse myocardial remodeling. Fluorofenidone (1-(3-fluorophenyl)-5-methyl-2-(1H)-pyridone, AKF-PD) is a novel pyridone antifibrotic agent, which exerts a strong antifibrotic effect. This study investigated the potential role of AKF-PD in suppressing cardiac myofibroblast conversion induced by transforming growth factor-beta1 (TGF-beta1) and the related mitogen-activated protein kinase (MAPK) signaling pathways in neonatal rat cardiac fibroblasts. The MAPK inhibitors used for pathway determination are c-Jun NH(2)-terminal kinase (JNK) inhibitor II (JNK inhibitor), PD98059 (extracellular signal-regulated kinase inhibitor (ERK) inhibitor) and SB203580 (p38 MAPK inhibitor). Cell proliferation was evaluated by multiply-table tournament (MTT) assay. The expressions of fibronectin (FN), alpha-SMA, phosphorylated ERK1/2 (pERK1/2) and ERK1/2 were investigated using Western blot analysis. AKF-PD remarkablely reduced the proliferative response of cardiac fibroblasts by 27.57% compared with TGF-beta1 stimulated group. AKF-PD, PD98059, and JNK inhibitor II completely prevented TGF-beta1-induced FN protein production. In addition, AKF-PD, PD98059 and SB203580 greatly attenuated alpha-SMA expression induced by TGF-beta1. Furthermore, AKF-PD significantly blocked TGF-beta1-induced phosphorylation of ERK. These results indicate that (1) AKF-PD inhibits TGF-beta1-induced myofibroblast differentiation; (2) the anti-fibrotic effects of AKF-PD are partially mediated by ERK phosphorylation.     

Selective pharmacological inhibitors reveal differences between Thy-1- and T cell receptor-mediated signal transduction in mouse T lymphocytes

A compelling body of evidence suggests a role for Thy-1 (CD90), a cell surface glycoprotein of mouse T lymphocytes, in signal transduction resulting in T cell activation. Despite more than 3 decades of investigation, intracellular biochemical events governing the Thy-1 signaling cascade are only vaguely understood. We have employed selective pharmacological inhibitors of signaling molecules to compare downstream elements participating in the Thy-1 signal transduction pathway with those involved in the T cell receptor (TCR)/CD3-associated signaling pathway. Mitogenic anti-Thy-1 or anti-CD3 monoclonal antibody (mAb) were used to cause T cells from C57BL/6 mice to proliferate in the presence or absence of different pharmacological inhibitors. Cyclosporine A, herbimycin A, LY294002, calphostin C and PD98059 all inhibited anti-Thy-1-induced T lymphocyte proliferation, indicating the involvement of calcineurin, protein tyrosine kinases, phosphatidylinositol 3-kinase, protein kinase C, and MEK1 (MAPK kinase 1), respectively, in Thy-1 signaling. Similar results were obtained when T cells were stimulated through the TCR with anti-CD3 monoclonal antibody in the presence or absence of the different inhibitors. Interestingly, the p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580 augmented anti-Thy-1-induced T cell proliferation, whereas anti-CD3-induced proliferative response was partially suppressed by the same inhibitor. The Thy-1 signal transduction pathway, therefore, shares a requirement for calcineurin and several major kinase families with the TCR signaling pathway. However, Thy-1 and TCR-associated signaling pathways are differentially regulated by p38 MAPK.     

Participation of various kinases in staurosporine induced apoptosis of RAW 264.7 cells

Staurosporine induced apoptosis of RAW 264.7 cells, a mouse macrophage-like cell line, as determined by DNA fragmentation, the increase of annexin V-stained cells, and the cleavage of poly(ADP-ribose)polymerase (PARP), a substrate of caspase. Analysis of the increase in the percentage of sub-G(1) cells revealed that the DNA fragmentation occurred in a time- and concentration-dependent manner at 0.021-2.1 microM of staurosporine. Staurosporine induced phosphorylation of p38 mitogen-activated protein kinase (MAPK) but suppressed spontaneous phosphorylation of p44/42 MAPK. The p38 MAPK inhibitor SB203580, the MAPK/extracellular signal-regulated kinase kinase inhibitor PD98059 and the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 potentiated the staurosporine-induced PARP cleavage and DNA fragmentation. The protein kinase A (PKA) inhibitor H-89 potentiated the staurosporine-induced DNA fragmentation without potentiating the PARP cleavage. In contrast, the protein kinase C (PKC) inhibitor Ro-31-8425 suppressed the PARP cleavage and DNA fragmentation. These findings suggested that staurosporine induces apoptosis via the caspase cascade in RAW 264.7 cells. The staurosporine-induced apoptosis is positively regulated by PKC, negatively regulated by p38 MAPK, p44/42 MAPK and PI3K via the caspase cascade, and negatively regulated by PKA without regulation of caspase activation.     

Cryptotanshinone inhibits chemotactic migration in macrophages through negative regulation of the PI3K signaling pathway

BACKGROUND AND PURPOSE: Cryptotanshinone, the major tanshinone isolated from Salvia miltiorrhiza Bunge, exhibits anti-inflammatory activity. However, there is no report on the effect of cryptotanshinone on recruitment of leukocytes to inflammatory sites. We therefore assessed the effects of cryptotanshinone on macrophage chemotaxis. EXPERIMENTAL APPROACH: Macrophage migration induced by complement 5a (C5a) or macrophage inflammatory protein-1alpha (MIP-1alpha) was measured in vitro. Intracellular kinase translocation and phosphorylation was assessed by Western blotting. KEY RESULTS: RAW264.7 cell migration towards C5a (1 microg ml(-1)) was significantly inhibited by cryptotanshinone (1, 3, 10 and 30 microM) in a concentration-dependent manner. Primary human macrophages stimulated by C5a were similarly inhibited. C5a-evoked migration in RAW264.7 cells was significantly suppressed by wortmannin (phosphatidylinositol 3-kinase (PI3K) inhibitor), PD98059 (MEK1/2 inhibitor) and SB203580 (p38 mitogen-activated protein kinase (MAPK) inhibitor), but not by SP600125 (c-Jun N-terminal kinase (JNK) inhibitor), suggesting that activation of PI3K, ERK1/2 and p38 MAPK signal pathways was involved in responses to C5a. Western blotting revealed that cryptotanshinone significantly inhibited PI3K-p110gamma membrane translocation and phosphorylation of Akt (PI3K downstream effector protein) and ERK1/2 induced by C5a. However, neither p38 MAPK nor JNK phosphorylation was affected by cryptotanshinone. Wortmannin significantly attenuated C5a-induced PI3K-p110gamma translocation, Akt and ERK1/2 phosphorylation. PD98059 suppressed ERK1/2 phosphorylation but failed to modify PI3K-p110gamma translocation by C5a stimulation. Furthermore, MIP-1alpha-induced cell migration and PI3K-p110gamma translocation were also inhibited by cryptotanshinone in a concentration-dependent manner. CONCLUSIONS AND IMPLICATIONS: Inhibition of macrophage migration by cryptotanshinone involved inhibition of PI3K activation with consequent reduction of phosphorylation of Akt and ERK1/2.     

Activation of phosphoinositide 3-kinase, protein kinase C, and extracellular signal-regulated kinase is required for oridonin-enhanced phagocytosis of apoptotic bodies in human macrophage-like U937 cells

Our previous study showed that oridonin isolated from Rabdosia rubescens enhanced phagocytosis of apoptotic cells by macrophage-like U937 cells through tumor necrosis factor (TNF) alpha and interleukin (IL)-1beta release. In this study, we further investigated signaling events involved in oridonin-augmented phagocytosis. Phagocytic stimulation was significantly suppressed by inhibitors, including a phosphoinositide 3-kinases (PI3K) inhibitor (wortmannin), a protein kinase C (PKC) inhibitor (stauroporine), and a phospholipase C (PLC) inhibitor (U73122). Exposure of U937 cells to oridonin caused an increase in PKC activity time- dependently, which was prevented by pretreatment with inhibitors of PI3K and PLC. Simultaneously, the activation of protein kinase B (PKB/Akt) and the increased expression of PLCgamma2 were also blocked by wortmannin. In addition, an extracellular signal-regulated kinase (ERK) MAPK inhibitor, PD98059, suppressed oridonin-augmented phagocytosis, whereas the p38 MAPK inhibitor (SB203580) and c-Jun N-terminal kinase (JNK) MAPK inhibitor (SP98059) had no inhibitory effect. Furthermore, pretreatment of U937 cells with anti-TNFalpha and anti-IL-1beta antibodies blocked oridonin-induced phagocytic stimulation as well as phosphorylation of ERK, but did not block the activation of PKC, indicating that these signaling events are triggered by oridonin, whereas secreted TNFalpha or IL-1beta only activate the ERK-dependent pathway. Taken together, oridonin is suggested to enhance phagocytosis of apoptotic bodies by activating PI3K, PKC, and ERK-dependent pathways.     

Effect of bradykinin on bradykinin-B2 receptor in rat aortic vascular smooth muscle cells and the involved signal transduction pathways

The aim of this paper is to study the effect of bradykinin (BK) on bradykinin-B2 receptor as well as the possible involved signal transduction pathways in cultured rat aortic vascular smooth muscle cells (VSMCs). Rat aortic VSMCs were cultured. Cells after 4–6 passages were used in the experiment. VSMCs were incubated with BK, BK + B2 receptor inhibitor (HOE-140), BK + MEK inhibitor (PD98059), BK + mitogen-activated protein kinase (MAPK) inhibitor (apigenin), BK + phosphoinositide 3-kinase (PI3K) inhibitor (LY294002), and BK + Akt inhibitor to evaluate the expression of B2 receptor and phosphorylation of signaling molecules MAPK, Akt, and PI3K by Western blot. (1) BK markedly up-regulated the expression of B2 receptor in VSMC. (2) Apigenin, PD98059, Akt inhibitor, and LY294002 inhibited upregulation of B2 receptor induced by BK. (3) Signal transduction pathways of MAPK and PI3K were involved in the up-regulation of B2 receptor by BK mediation. Results suggest that bradykinin can up-regulate the expression of B2 receptor in VSMCs.     

p38 mitogen-activated protein kinase contributes to angiotensin II-stimulated migration of rat aortic smooth muscle cells

In this study, we clarified the intracellular mechanism of angiotensin II (Ang II) in promoting migration in rat aortic smooth muscle cells (RASMCs). RASMC migration was measured with the Boyden chamber assay, and the result was confirmed with an aortic sprout assay. The activities of kinases were investigated by western blot analysis. Ang II enhanced RASMC migration, which was chemotaxis directed, and induced the phosphorylation of p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase 1/2 (ERK1/2), and heat shock protein 27 (Hsp27). Ang II-enhanced cell migration was inhibited by SB203580 (a p38 MAPK inhibitor) and piceatannol (a spleen tyrosine kinase inhibitor), but only partially by PD98059 (an ERK inhibitor) and PP2 (a Src inhibitor). The Ang II-stimulated phosphorylation of p38 MAPK and Hsp27 in RASMCs was inhibited by piceatannol and SB203580. The phosphorylation of ERK1/2 stimulated by Ang II was suppressed by PD98059, piceatannol, and PP2. Ang II increased the sprout outgrowth from aortic rings and this response was attenuated by pretreatment with SB203580, PD98059, PP2, or piceatannol. These results suggest that p38 MAPK contributes to the regulation of the Ang II-induced chemotactic migration of vascular smooth muscle cells, which is mediated by Hsp27 phosphorylation.     

Beta-sitosterol-induced-apoptosis is mediated by the activation of ERK and the downregulation of Akt in MCA-102 murine fibrosarcoma cells

Beta-sitosterol (SITO) is a potential candidate for cancer chemotherapy, however, little is known about the cellular and molecular mechanisms in cancer cells. We herein identified how SITO induces anti-proliferation and cell death in MCA-102 fibrosarcoma cells. SITO exposure induced-apoptosis and the cell death resulted from a significant loss of the Bcl-2 and the inhibitor of apoptosis protein (IAP) family (XIAP, cIAP-1 and cIAP-2), and increased Bax with an alteration of p53 and p21. SITO-induced cell death significantly also increased caspase activity and poly(ADP-ribose) polymerase (PARP) cleavage, and caspase-3 inhibitor z-DEVD-fmk significantly inhibited SITO-induced cell death. These data suggest that the activation of caspase-3 is associated with SITO-induced-apoptosis. Treatment with SITO also induced phosphorylation of extracellular-signal regulating kinase (ERK) and p38 mitogen-activated protein kinase (MARK), but not c-Jun N-terminal kinase (JNK). A specific ERK inhibitor PD98059 significantly blocks SITO-induced-apoptosis, whereas a JNK inhibitor SP600125 has no affect. A p38 MAPK inhibitor SB203580 very slightly suppressed cell death. The induction of apoptosis was also accompanied by an inactivation of phosphatidylinositol 3-kinase (PI3K)/Akt, and PI3K inhibitor LY29004 significantly increases SITO-induced cell death. These findings provide evidence demonstrating that the proapoptotic effect of SITO is mediated through the activation of ERK and the block of the PI3K/Akt signal pathway in MCA-102 cells. Therefore, SITO has a strong potential as a therapeutic agent for preventing cancers such as fibrosarcoma.     

Differential regulation of eotaxin-1/CCL11 and eotaxin-3/CCL26 production by the TNF-alpha and IL-4 stimulated human lung fibroblast

Allergic asthma and allergic dermatitis are chronic inflammatory diseases and are characterized by an accumulation of eosinophils at sites of inflammation. Eotaxin-1/CCL11 and eotaxin-3/CCL26 are members of the CC chemokine family, which are known to be potent chemoattractants for eosinophils. We observed that a human lung fibroblast, HFL-1 produces eotaxin-1 and -3 in response to TNF-alpha plus IL-4 stimulation, accompanied with NF-kappaB and STAT6 activation. We explored which signaling pathways are operative in the production of eotaxin-1 and -3 using several inhibitors. Eotaxin-1/CCL11 production was inhibited by a p38 mitogen-activated protein kinase (MAPK) inhibitor, SB203580, but not by the MEK (MAPK/ERK kinase) inhibitors, PD98059 and U0126. In contrast, eotaxin-3/CCL26 production was inhibited similarly by PD98059 as well as U0126 and SB203580. In addition, two proteasome inhibitors, N-acetyl-leucyl-leucyl-norleucinal (ALLN) and bortezomib with significant inhibitory activity on NF-kappaB activation, inhibited eotaxin-1/CCL11 production with IC(50) 8 muM for ALLN and IC(50) 16 nM for bortezomib. In contrast, eotaxin-3/CCL26 production was not inhibited significantly up to 10 muM of ALLN (IC(50 )16 muM) and up to 10 nM of bortezomib (IC(50) 11 nM), giving inhibition of eotaxin-3/CCL26 less sensitive than eotaxin-1/CCL11 production by the proteasome inhibitors. Synergistic inhibition was observed among lower doses of SB203580 and proteasome inhibitors, particularly in the eotaxin-1/CCL11 production. No such prominent synergism was found on the eotaxin-3/CCL26 production. The suppression of eotaxin family production by these inhibitors may be efficacious against allergic diseases.