肝癌细胞VEGF转录调控的信号传导通路

目的研究磷脂酰肌醇3-激酶(PI3K)和p42／p44丝裂源激活的蛋白激酶(MAPK)在肝癌细胞血管内皮生长因子(VEGF)转录调控中的作用。方法应用缺氧诱导剂氯化钴或重组人表皮生长因子(EGF)刺激HepG2细胞中VEGF的转录，在此过程中应用PI3K特异性阻断剂LY294002或p42／p44 MAPK特异性阻断剂PD98059干预，采用半定量逆转录PCR检测VEGF mRNA表达的变化。结果氯化钴或EGF可以诱导HepG2细胞中VEGF的表达。PI3K阻断剂LY294002可以在一定范围内浓度依赖性地抑制VEGF mRNA的表达，而p42／p44 MAPK阻断剂PD98059对VEGF mRNA的表达无抑制作用。结论肝癌细胞VEGF的转录调控受PI3K通路调控，而不受p42／p44 MAPK调控。     

低盐诱导的致密斑细胞环氧化酶2表达与p38丝裂素激活蛋白激酶信号通路

目的 探讨低盐(LS)培养对小鼠致密斑细胞 (MMDD1)环氧化酶2 (COX-2)表达、前列腺素E2(PGE2)释放的诱导作用及p38丝裂素激活蛋白激酶(MAPK)信号通路的调控作用。方法 采用RT-PCR和免疫印迹方法检测正常盐(NS)与LS培养对MMDD1细胞COX-2表达的影响。用ELISA法检测上清液PGE2的含量。用免疫印迹检测细胞内p-p38 MAPK表达的变化。 结果 与NS培养相比,LS培养均能诱导MMDD1细胞COX-2 mRNA和蛋白表达增加(16 h时高峰 mRNA 0.94±0.12比0.26±0.09,28 h时高峰蛋白0.59±0.02比0.25±0.07,P均< 0.01);PGE2分泌各时间点均显著升高,于24 h达高峰 [(644.33±26.54)ng/L比(224.0±18.33)ng/L, P < 0.01。LS培养后,MMDD1细胞内p38MAPK的磷酸化程度显著上调,180 min时较高(从0.17±0.01升至0.28±0.01,P < 0.01)。20 μmol/L p38抑制剂SB-203580下调 LS诱导的COX-2蛋白表达(从0.58±0.01降至0.19±0.02, P < 0.01)。 结论 低盐培养促进MMDD1细胞COX-2的表达和PGE2的分泌。p38 MAPK激活介导了低盐诱导的MMDD1细胞COX-2表达。     

三氧化二砷诱导前列腺癌PC-3细胞凋亡P_(38)信号通路的研究

目的:探讨P38信号通路在三氧化二砷(As2O3)诱导雄激素非依赖性前列腺癌PC-3细胞凋亡中的作用。方法:应用四甲基偶氮唑蓝(MTT)法检测不同浓度(0.312 5、0.625、1.25、2.5、5、10、20μmol/L)As2O3作用PC-3细胞24、48、72 h后的细胞生长抑制情况。Western印迹检测As2O3作用PC-3细胞后P38信号转导通路的表达。Annexin V/PI双染色法检测As2O3作用PC-3细胞后细胞凋亡,同时检测应用P38通路高选择抑制剂SB203580干扰P38信号通路后As2O3诱导PC-3细胞凋亡的变化。结果:As2O3诱导PC-3细胞凋亡呈现时间、剂量依赖性。As2O3可以使P38信号通路蛋白快速磷酸化,激活P38信号通路。2、10、20μmol/L As2O3作用PC-3细胞24 h后,PC-3细胞凋亡率分别为(18.9±0.43)%、(24.7±0.29)%和(49.7±1.79)%。应用P38信号通路高选择抑制剂SB203580干扰P38信号通路后,PC-3细胞凋亡率分别降低为(14.8±0.81)%、(22.1±0.51)%和(39.6±1.74)%,抑制P38信号通路可以显著降低As2O3诱导PC-3细胞的凋亡(P<0.05)。结论:P38信号通路在As2O3诱导雄激素非依赖性前列腺癌PC-3细胞凋亡中有表达,干扰P38信号通路可影响As2O3诱导PC-3细胞凋亡,提示P38信号通路参与了As2O3诱导的PC-3细胞凋亡。     

靶向抑制PI3K对人体外周血破骨细胞分化p38/c-Fos 信号通路调控的研究

目的探讨靶向抑制磷脂酰肌醇3-激酶(PI3K)调控p38/c-Fos信号通路对破骨细胞分化的影响。方法采用人体外周血分离单个核细胞,并诱导形成破骨细胞,干预组应用靶向抑制PI3K的LY294002对细胞进行处理,通过细胞形态学观察并检测细胞活性,再分别采用RT-PCR和Western-Blot两种方法考察p38MAPK通路及下游转录因子c-fos基因和蛋白的表达水平。结果模型组与干预组细胞形态学观察均可见诱导培养的破骨细胞形态明显;与模型组比较,干预组破骨细胞样细胞的形成减少,活性减弱,具有统计学意义(P0.05);RT-PCR结果均显示,干预组p38MAPK通路下游转录因子c-fos表达水平较对照组下降,有显著性差异(P0.01);Western-Blot检测结果显示干预组c-fos蛋白表达水平较对照组降低,具有统计学意义(P0.05)。结论靶向抑制PI3K在体外细胞培养中可抑制破骨细胞形态,并可通过下调p38MAPK通路中c-fos基因和蛋白水平的表达,从而减弱破骨细胞吸收功能。     

结缔组织生长因子诱导人近端肾小管上皮细胞整合素连接激酶的表达及与激酶信号途径的关系

目的探讨结缔组织生长因子（CTGF）对人近端肾小管上皮细胞系HK-2整合素连接激酶（ILK）表达的影响，以及丝裂原激活蛋白激酶（MAPK）和磷脂酰肌醇3激酶（P13-K）途径对该因子表达的影响。方法用不同浓度的CTGF作用HK-2细胞24h及50μg／L的CTGF作用HK-2细胞不同时间，以实时PCR和Western印迹方法检测ILKmRNA及蛋白的表达。用信号通路特异性抑制剂预处理，观察其对CTGF的干预作用。结果CTGF呈时间及浓度依赖性诱导人近端肾小管上皮细胞ILK蛋白表达。5、20、50μg／L的CTGF可使ILK表达量分别增加为对照组的3．284、5．103、5．638倍。50μg／LCTGF使ILK的表达在6h开始升高，高峰在48h（为对照组5．740倍），MEK抑制剂PD98059和P13．K抑制剂LY294002显著降低CTGF诱导的HK-2细胞ILK基因和蛋白的表达（P均〈0．05）。p38MAPK抑制剂SB203580对CTGF诱导的ILK表达无显著影响。结论CTGF能诱导HK-2细胞ILK蛋白的表达，该作用可能与ERK1／2和P13-K信号途径激活有关。     

p38MAPK信号通路在盐酸戊乙奎醚减轻内毒素诱导人脐静脉内皮细胞损伤中的作用

目的 探讨p38丝裂原活化蛋白激酶(p38 MAPK)信号通路在盐酸戊乙奎醚减轻内毒素诱导人脐静脉内皮细胞损伤中的作用.方法 培养人脐静脉内皮细胞,以1×104/ml密度接种于96孔培养板(100μl/孔)或24孔培养板(3 ml/孔),以1×106/ml密度接种于培养瓶(5 ml/瓶),采用随机数字表法,将其随机分为4组(n=23):正常对照组(C组)、脂多糖(LPS)组(L组)、盐酸戊乙奎醚组(P组)和盐酸戊乙奎醚+LPS组(PL组),P组和PL组加入终浓度为2μg/ml的盐酸戊乙奎醚,L组和PL组加入终浓度为1 μg∥ml的LPS,PL组于加入盐酸戊乙奎醚后1h加入LPS.加入LPS后24h时,收集细胞,测定磷酸化p38 MAPK(p-p38 MAPK)和p38 MAPK的表达水平,以二者比值反映p38 MAPK激活程度,并测定细胞活力、NO含量和诱导型一氧化氮合酶(iNOS)表达.结果 与C组比较,L组细胞活力降低,NO、p-p38 MAPK和p38 MAPK激活程度升高,iNOS表达上调(P＜0.01),P组上述指标差异无统计学意义(P＞0.05);与L组比较,PL组细胞活力升高,NO、p-p38 MAPK和p38 MAPK激活程度降低,iNOS表达下调(P＜0.05或0.01).结论 p38 MAPK信号通路参与了盐酸戊乙奎醚减轻内毒素诱导人脐静脉内皮细胞损伤的作用.     

表皮生长因子对人小细胞肺癌细胞Survivin表达的影响及其机制

目的 探讨表皮生长因子(EGF)对人小细胞肺癌NIC-H446细胞中凋亡抑制因子Survivin表达的影响及其调控Survivin的机制.方法 噻唑蓝(MTT)法测定EGF对细胞增殖率的作用.逆转录-聚合酶链反应(RT-PCR)和免疫印迹(Western blot)方法测定EGF对NIC -H446细胞Survivin表达的影响.Western blot方法测定EGF对NIC-H446细胞p38丝裂原活化激酶(p38MAPK)、磷酸化p38MAPK(p-p38MAPK)、c-Jun氨基端激酶(JNK)、磷酸化JNK (p-JNK)、细胞外信号调节蛋白激酶(ERK)、磷酸化ERK(p-ERK)信号通路蛋白的表达影响.结果 EGF可促进NIC-H446细胞增殖,具有浓度-时间依赖性.与对照组(0.36±0.06、0.57 ±0.15)比较,EGF组Survivin mRNA(0.69±0.12)和蛋白(0.89±0.19)表达明显升高(P＜0.01).与对照组(0.29±0.08)比较,EGF组p-p38MAPK蛋白表达水平(0.68±0.27)明显上升(P＜0.01),其他蛋白表达均无明显变化.EGF+ SB203580组Survivin蛋白表达(0.56±0.17)、p-p38MAPK蛋白表达(0.41±0.11)显著低于EGF组(0.92 ±0.21、0.72 ±0.19,P＜0.01),与对照组比较差异无统计学意义.结论 EGF通过活化p38MAPK信号通路上调小细胞肺癌细胞中Survivin的表达,促进细胞增殖,这可能是小细胞肺癌发展的重要机制.     

热损伤诱导的丝裂原活化蛋白激酶对活化蛋白-1的影响及其意义

目的 观察成纤维细胞热烫伤后丝裂原活化蛋白激酶以及活化蛋白-1的表达。方法 将培养的人成纤维细胞分成4组：(1)单纯热损伤刺激组；(2)热损伤刺激 碱性成纤维细胞生长因子处理组(10μg／L)；(3)预先加入PD98059(10μmoL/L)，再行热损伤 碱性成纤维细胞生长因子(bFGF)刺激；(4)预先加入PD98059 SB203580(各10μmol／L)阻断剂30min，再行热损伤 碱性成纤维细胞生长因子刺激。伤后0、30、60和180min检测细胞外信号调节激酶(ERK)和原癌基因c-fos蛋白。结果单纯热刺激的成纤维细胞ERK表达增加，随后消失。碱性成纤维细胞生长因子刺激ERK表达增加显著，时间延长。加入PD98059拮抗剂，ERK的表达受抑制。原癌基因c-fos的表达开始增加，随后减弱。同时阻断ERK和p38MAPK两条通路，c-fos弱阳性表达。结论 碱性成纤维细胞生长因子引起热损伤成纤维细胞ERK表达增加，原癌基因c-fos是MAPK信号通路下游重要的靶蛋白。     

脊髓糖皮质激素受体在吗啡耐受大鼠PI3K/Akt信号通路中的作用

目的 探讨脊髓糖皮质激素受体(GR)在吗啡耐受大鼠磷脂酰肌醇-3激酶/蛋白激酶B(PI3K/Akt)信号通路中的作用.方法 健康雄性SD大鼠,8～ 10周龄,体重300 ～ 350 g,取鞘内置管成功的大鼠40只,采用随机数字表法,将大鼠随机分为4组(n=10):对照组(C组)鞘内注射生理盐水10μl;吗啡耐受组(M组)鞘内注射吗啡10 μg;地塞米松组(GR激动剂,DEX组)鞘内注射地塞米松4μg,30 min后注射吗啡10 μg; RU38486组(GR阻断剂,R组)鞘内注射RU38486 2 μg,30 min后注射吗啡10 μg.注射药物容量均为10μl,2次/d,连续7d.于每天第1次鞘内给药前和鞘内给药结束后1d测定甩尾潜伏期,计算最大抗伤害效应百分比( MPAE),最后一次甩尾潜伏期测定结束后,取脊髓背角组织,测定PI3K、Caspase-3的表达水平和Akt活性.结果 M组、DEX组和R组发生了吗啡耐受,C组未发生吗啡耐受.与C组比较,M组脊髓背角Akt活性降低,PI3K表达下调,Caspase-3表达上调(P＜0.01);与M组比较,DEX组MPAE和Akt活性降低,PI3K表达下调,Caspase-3表达上调,R组MPAE和Akt活性升高,PI3K表达上调,Caspase-3表达下调(P＜0.05).结论 脊髓GR可通过抑制PI3K/Akt信号通路参与吗啡耐受的形成.     

姜黄素与LY294002联合应用对前列腺癌PC-3细胞体外生长的影响

【摘要】 目的〓探讨姜黄素与PI3K/Akt抑制剂LY294002联合应用对前列腺癌PC-3细胞体外生长的影响。方法〓根据给药不同将实验分为对照组、姜黄素组、LY294002组和姜黄素组+LY294002联合组,分别加入等量的培养基、25 μmoL/L姜黄素、25 μmoL/L的LY294002和两种混合液。采用MTS法检测各组细胞的增殖情况、流式细胞仪术检测各组细胞凋亡情况、q-PCR测定各组细胞中NF-κB、P53及caspase-9的表达情况。结果〓姜黄素组、LY组和联合组的细胞增值率均较对照组明显降低,且联合组明显低于两个单独用药组(P<0.05)。姜黄素与LY294002联合作用前列腺癌PC-3细胞后,细胞总凋亡率较姜黄素及LY294002单独使用后明显增加(P值均<0.05)。联合用药组的NF-κB表达量明显低于两单独用药组(P<0.05),而P53和caspase-9的表达量均明显高于两单独用药组(P<0.05)。结论〓姜黄素与LY294002联合使用较两种药物单独使用更能有效抑制前列腺癌PC-3细胞的体外生长,作用机制可能是通过抑制NF-κB的表达从而抑制细胞增殖,并增加P53和caspase-9的表达从而促进细胞凋亡来实现的。     

米非司酮诱导雄激素非依赖性前列腺癌细胞凋亡的实验研究

目的探讨米非司酮在体外诱导雄激素非依赖性前列腺癌DU-145、PC-3细胞凋亡的作用。方法采用四甲基偶氮唑蓝法检测1,10,50和100μmol／L米非司酮作用于前列腺癌DU-145、PC-3细胞24～120h的吸光度（A）值,用流式细胞仪检测10μmol／L米非司酮作用24和48h后DU．145、PC-3细胞凋亡率的变化;采用免疫组化法检测米非司酮作用DU-145、PC．3细胞后bax、bcl-2、血管内皮生长因子（VEGF）蛋白表达的变化。结果1μmol／L米非司酮组的A值与对照组相比,差异无统计学意义（P〉0．05）;10,50和100μmol／L米非司酮组的A值与对照组比较,差异有统计学意义（P〈0．01）;米非司酮对前列腺癌DU-145、PC-3细胞的抑制作用呈时间-剂量依赖性。10μmol／L米非司酮作用前列腺癌DU-145细胞24和48h的凋亡率分别为15．3％和30．4％,PC-3细胞的凋亡率分别为22．2％和32．0％。经10μmol／L米非司酮作用后,DU-145、PC-3细胞中VEGF和bcl-2蛋白的表达明显减少,而bax的表达显著增加（P〈0．05）。结论米非司酮以时间．剂量依赖性方式抑制激素非依赖性前列腺癌DU-145和Pc-3细胞的增殖,其作用可能是通过降低VEGF蛋白的表达。从而下调bcl-2、激活bax蛋白的表达来实现。     

Sphingosine-1-phosphate stimulates smooth muscle cell migration through galpha(i)- and pi3-kinase-dependent p38(MAPK) activation

BACKGROUND: Sphingosine-1-phosphate (S-1-P) is an extracellular mediator released in response to vessel injury. S-1-P binds to G-protein-coupled receptors, which can be Galpha(i)-, Galpha(q)-, or G(12/13)-linked. This study examines the role of p38 mitogen-activated protein kinase (p38(MAPK)) in vascular smooth muscle cell migration after stimulation with S-1-P, and pathways leading to p38(MAPK) activation. S-1-P has previously been shown to stimulate migration of vascular smooth muscle cells (VSMCs) in vitro through ERK1/2 and G(i). We hypothesized that S-1-P-induced VSMC migration is also dependent on p38(MAPK) activation through a G(i)-coupled extracellular receptor and phosphoinositide 3-kinase (PI3-K). METHODS: VSMCs were cultured in vitro. A linear wound assay was performed in the presence of S-1-P and inhibitors of p38(MAPK) (SB203580) or epidermal growth factor (EGF) receptor kinase (AG1478). Chemotaxis stimulated by S-1-P was also assayed in a modified Boyden chamber with and without SB203580 pretreatment. Western blotting was performed to examine p38(MAPK) activation in response to S-1-P with and without SB203580, AG1478, or inhibitors of G(i) (pertussis toxin), PI3-K (Wortmannin and LY294002), or MEK1 (PD98059). Western blotting and immunoprecipitation for targets of p38(MAPK) (MAPKAP kinase-2) and PI3-K (Akt) were also performed.S-1-P stimulated migration of VSMCs in both wound and Boyden transwell assays. This migration was inhibited by SB203580 to the level of control, whereas AG478 had no effect. RESULTS: S-1-P stimulated activation of p38(MAPK) that peaked at 10 min, as well as activation of MAPKAP kinase-2. Activation of p38(MAPK) was significantly inhibited by SB203580, pertussis toxin, Wortmannin, and LY294002, but not by PD98059 or AG1478; MAPKAP kinase-2 activation was inhibited by SB203580. Akt was activated by S-1-P at 3 to 5 min; this response was inhibited by Wortmannin and LY294002, but not by SB203580 or pertussis toxin. CONCLUSIONS: S-1-P induced VSMC migration through a G(i)-linked and a PI3-K coupled, p38(MAPK)- dependent process. PI3-K appears to function upstream of p38(MAPK), but was not G(i)-dependent. S-1-P-stimulated activation of p38(MAPK) does not signal via transactivation of the EGF receptor. Understanding signal transduction will allow targeted molecular interventions to treat the response of a vessel to injury.     

重组人红细胞生成素预处理对肾小管上皮细胞缺血再灌注损伤中PI3K-Akt-GSK-3β通路的调控作用

目的 探讨磷脂酰肌醇-3激酶（PI3K）-蛋白激酶B（Akt）-糖原合成酶激酶3β（GSK-3β）通路对人肾小管上皮细胞（HK-2）缺血再灌注（IR）损伤过程中细胞凋亡的调控及重组人红细胞生成素（rHuEPO）的保护作用。 方法 正常培养的HK-2细胞,分为7组：正常对照组、IR组、LY294002干预组（PI3K-Akt阻断剂,10 μmol/L）、LiCl干预组（GSK-3β阻断剂,20 μmol/L）、rHuEPO干预组（20 U/L）、rHuEPO+LY294002干预组、rHuEPO+LiCl干预组。Western印迹法检测Akt（Ser473）、GSK-3β（Ser9）及半胱氨酸天冬氨酸蛋白酶（caspase-3）活性; MTT法检测细胞活力;Annexin V和PI染色结合流式细胞仪技术检测细胞凋亡。 结果 IR损伤诱导HK-2细胞凋亡率上调（15.20%±1.43％）、Akt活性水平下降、GSK-3β及caspase-3酶活性水平上调,与正常对照组相比,差异有统计学意义（P < 0.05）。与IR组相比,LY294002干预使细胞凋亡率进一步上调（18.20%±2.06％）、Akt活性水平下调、GSK-3β及caspase-3酶活性上调,LiCl干预使细胞凋亡率下调（12.30%±0.85％）、Akt活性水平上调、GSK-3β及caspase-3酶活性下调,差异均有统计学意义（P < 0.05）。rHuEPO干预与IR组相比,细胞凋亡率下降（11.10%±1.62％）、Akt活性水平升高而GSK-3β及caspase-3酶活性下调,差异有统计学意义（P < 0.05）。与rHuEPO干预相比,rHuEPO+LY294002双干预细胞凋亡率升高（13.40%±1.94％）、Akt活性水平下降而GSK-3β及caspase-3酶活性上调,rHuEPO+LiCl双干预细胞凋亡率下调（7.50%±1.31％）、Akt活性水平上升而GSK-3β及caspase-3酶活性下降,差异均有统计学意义（P < 0.05）。 结论 IR损伤可引起肾小管上皮细胞凋亡,Akt活性降低及GSK-3β活性升高,影响caspase-3依赖的外源性凋亡途径可能是其凋亡机制之一。rHuEPO可通过增强Akt活性,降低GSK-3β及caspase-3酶活性,从而减轻细胞凋亡,对HK-2 IR损伤有一定的保护作用。     

三氧化二砷对前列腺癌细胞株PC-3生长影响的研究

目的 :探讨三氧化二砷 (As2 O3 )对雄激素非依赖性人前列腺癌细胞株PC 3生长的影响及其机制。　方法 :通过光学显微镜观察As2 O3 处理前后培养的PC 3细胞生长和形态的变化 ,采用MTT法了解不同浓度As2 O3 作用后PC 3细胞的生长抑制曲线 ,应用流式细胞仪Annexin V FITC/PI双染法分析不同浓度As2 O3 处理的PC 3细胞的凋亡情况。　结果 :As2 O3 作用后 ,PC 3细胞形状变圆 ,体积变小 ,胞质透亮度下降 ,部分细胞脱落悬浮于培养基中。在7.81 2 5、1 5 .6 2 5、31 .2 5 0、6 2 .5 0 0、1 2 5、2 5 0、5 0 0 μmol/LAs2 O3 作用 4 8h和 72h后 ,MTT法检测细胞生长抑制率分别为(0 .0 6± 0 .99)、(1 5 .0 1± 1 .1 2 )、(2 9.2 1± 1 .31 )、(34.32± 1 .1 4 )、(4 0 .5 1± 1 .81 )、(6 9.39± 1 .74 )、(73.1 9± 2 .4 1 ) %和(0 .0 4± 1 .5 1 )、(1 6 .1 9± 1 .0 4 )、(4 3.6 1± 1 .1 2 )、(5 6 .6 6± 1 .2 3)、(73.1 3± 2 .6 1 )、(85 .2 2± 1 .74 )、(91 .4 1± 2 .81 ) %。用流式细胞仪检测经过 0 (对照组 )和 0 .1、1 .0、3.0、5 .0、2 0 .0、5 0 .0 μmol/LAs2 O3 作用 4 8、72h后的PC 3细胞 ,凋亡率分别为 0 .87%、5 .33%、8.94 %、9.6 6 %、1 2 .5 6 %、4 5 .5 9%、6 9.0 9%和 0 .1 3%、1 3.4 9%、     

High uric acid induces phenotypic transition of renal tubular cells via PI3K/Akt signaling pathway

Objective To investigate the effect and the mechanism of epithelial-mesenchymal transition (EMT) in renal tubular cells induced by uric acid. Methods Normal rat kidney tubular cell line (NRK-52E) were exposed to different concentrations of uric acid (100, 200, 400, 600, 800 μmol/L UA) for 48 hours to induce EMT. Morphological changes of the NRK-52E cells were examined under an inverted phase contrast microscope. The protein expression of E-cadherin, α-SMA, p-Akt and Akt were detected by Western blotting. The distribution of E-cadherin and α-SMA were detected by immunofluorescence. NRK-52E cells were pretreated by different concentrations of LY294002(0, 2.5, 5, 10, 15 μmol/L), the inhibitor of PI3K/p-Akt signaling pathway, and then processed by uric acid (400 μmol/L) for 48 hours. Western blotting was used to detect the protein expression of p-Akt and Akt. NRK-52E cells were then divided into four groups: normal group (N), uric acid group (UA), LY294002 group (LY), uric acid with LY294002 group (UA+LY). The protein expression of E-cadherin and α-SMA were detected by Western blotting, the distribution of E-cadherin, α-SMA and p-Akt were detected by immunofluorescence. Results There was abundant cellular expression of E-cadherin in unstimulated renal tubular cells whereas its expression was significantly decreased in uric acid-stimulated cells (P＜0.05). In addition, uric acid induced de novo expression of α-SMA in contrast to almost negative staining in untreated cells (P＜0.05). p-Akt were obviously increased in high uric acid group (P＜0.05) and Akt changed not significantly (P＞0.05). NRK-52E cells transformed into elongated fibroblast-like cells from cuboidal clustered epithelial cells. These indicated that uric acid has induced EMT and activated PI3K/p-Akt signaling pathway in NRK-52E cells. However, the above effects of uric acid were abolished when p-Akt was blocked by the PI3K inhibitor (10, 15 μmol/L LY294002), indicated that LY294002 has reversed the trend of EMT. Conclusions High uric acid induces phenotypic transition of renal tubular cells probably via activating PI3K/Akt signaling pathway.     

Bile salt exposure causes phosphatidyl-inositol-3-kinase-mediated proliferation in a Barrett's adenocarcinoma cell line

BACKGROUND: The mechanisms by which gastroesophageal reflux promotes malignant progression in Barrett's esophagus are poorly understood. The phosphatidylinositol-3-kinase (PI3 kinase)/Akt pathway regulates proliferation and apoptosis. We hypothesized that the PI3 kinase/Akt pathway mediates the pro-proliferative and antiapoptotic effects of bile. METHODS: The Barrett's adenocarcinoma cell line, SEG-1, was exposed to the conjugated bile salt, glycochenodeoxycholic acid (GCDA). Cell number was measured by the MTT incorporation assay and by Coulter counter. PI3 kinase/Akt activity was inferred from Western blots of phosphorylated and total Akt. Proliferation and apoptosis were determined by BrdU incorporation and cell death ELISA. RESULTS: A dose-dependent cell number increase was seen with a 20-minute exposure to GCDA. On Western blot, 200 micromol/L GCDA caused a 3-fold increase in Akt phosphorylation within 20 minutes, which was inhibited by 90% with the addition of PI3 kinase inhibitor, LY294002. LY294002 produced dose-dependent inhibition of GCDA-induced cell number increases. 200 micromol/L GCDA decreased apoptosis by 25%. Addition of LY294002 did not completely inhibit the antiapoptotic effect of bile. CONCLUSIONS: Bile salts activate the PI3 kinase/Akt signaling pathway and stimulate cell growth in SEG-1. The majority of this PI3 kinase-mediated effect is secondary to increases in proliferation rather than to decreases in apoptosis.