PI3K/AKT/mTOR和MAPK/ERK信号通路在胃癌细胞中的相互作用机制

目的探讨磷脂酰肌醇3–激酶/蛋白激酶B/哺乳动物靶蛋白(PI3K/AKT/mTOR)、丝裂原活化蛋白激酶/细胞外信号调节激酶(MAPK/ERK)两条信号通路对胃癌细胞功能的影响及相互作用机制。方法使用PI3K抑制剂LY294002、mTOR抑制剂AZD8055、MEK抑制剂AZD6244单独或联合作用于胃癌MGC-803细胞。应用CCK8法检测细胞增殖;流式细胞术检测细胞凋亡和细胞周期;蛋白印迹法(Western blot)检测通路关键蛋白的表达。结果联合使用LY294002(25μmol/L)与AZD6244(125μmol/L)、AZD8055(0.1μmol/L)与AZD6244(125μmol/L)能够显著抑制胃癌MGC-803细胞的增殖活性,且联用组比单独作用组具有更强的抑制效果(P 0.05);联用组诱导细胞凋亡数量和阻滞于G0/G1期的MGC-803细胞数量增多,高于单独作用组(P 0.05)。与LY294002、AZD8055和AZD6244单独作用相比,LY294002与AZD6244、AZD8055与AZD6244联用组MGC803细胞p-AKT、p-P70S6K和p-ERK1/2蛋白表达明显受到抑制(P 0.05)。结论 PI3K/AKT/mTOR和MAPK/ERK两条信号通路在胃癌MGC-803细胞的生长中具有协同调控作用,对于两条信号通路的多靶点抑制能够更加明显的抑制癌细胞生长。     

EGCG通过PI3-K/Akt信号通路抗神经细胞缺氧/复氧损伤

目的研究表没食子儿茶素没食子酸酯(EGCG)对神经细胞缺氧/复氧(A/R)损伤的影响及其作用机制。方法原代培养神经细胞,实验分4组:对照组、A/R组、EGCG预处理组(EGCG+A/R组)、EGCG+LY294002+A/R组。检测细胞存活率与乳酸脱氢酶(LDH)活性;流式细胞仪检测细胞凋亡和[Ca~(2+)]i;Western blot法检测总-Akt和磷酸化-Akt(p-Akt)蛋白表达。结果与对照组相比,A/R组中细胞存活率降低;LDH、[Ca~(2+)]i与细胞凋亡增加。与A/R组相比,EGCG预处理显著降低LDH、[Ca~(2+)]i与细胞凋亡,提高细胞存活率,表明EGCG可对抗神经细胞A/R损伤。进一步结果显示EGCG预处理后,显著增加神经细胞中p-Akt蛋白表达。然而,PI3K-Akt信号转导通路阻断剂LY294002显著抑制EGCG介导的神经保护作用与p-Akt蛋白上调。结论 EGCG对A/R介导的神经细胞损伤具有保护作用,其保护作用与PI3K-Akt信号转导通路有关。     

皮质酮对海马HT-22细胞株锌含量的影响及机制研究

目的通过观察皮质酮(corticosterone,CORT)对海马HT-22细胞总锌含量的影响,对其可能机制进行探讨,为研究应激相关疾病提供实验依据。方法小鼠海马神经元HT-22细胞株,经10μmol/L CORT处理6h后,采用原子吸收分光光度计火焰法测定胞内总锌含量,并采用实时荧光定量PCR法检测MT1、MT3、ZnT1、ZnT3和ZIP1m RNA表达。结果与对照组相比,10μmol/L CORT处理HT-22细胞6h后,HT-22细胞内总锌含量显著下降,而先于CORT处理前加入糖皮质激素受体阻断剂RU486组总锌含量与对照组无明显变化。与对照组相比,CORT组HT-22细胞MT1、MT3、ZnT1、ZnT3、ZIP1 mRNA表达水平上升,而先于CORT处理前加入糖皮质激素受体阻断剂RU486组上述基因mRNA表达均无明显变化。结论 CORT可影响海马HT-22细胞锌稳态调节分子的表达,进而影响细胞锌稳态失衡。     

姜黄素抑制人肝癌细胞BEL-7402中VEGF和HIF-1α表达通过PI3K／AKT／FRAP信号传导通路

目的探讨MAPK和PI3K信号传导通路在姜黄素调节VEGF和HIF-1α表达中的作用。方法分别加入LY29400225μmol／L、50μmol／L，U012610μmol／L、20μmol／L，rapamycin 5ng／ml、10ng／ml处理人肝癌细胞BEL-7402，30min后加入姜黄素10μmol／L，对照组单独加入0、10μmol／L姜黄素，缺氧环境中培养6h后，行RT—PCR和Western Blot检测VEGF蛋白、mRNA和HIF-1α蛋白表达；分别加入不同浓度的的姜黄素以及LY294002 25 μmol／L处理人肝癌细胞BEL-7402，缺氧环境中培养6h后，行Western Blot检测磷酸化AKT和总AKT蛋白表达。结果姜黄素10μmol／L＋LY29400225μmol／L组、姜黄素10μmol／L＋LY294002 50 μmol／L组、姜黄素10μmol／L＋rapamycin 5 ng／ml组、姜黄素10μmol／L＋rapamycin 10 ng／na组HIF-1α蛋白、VEGF蛋白、mRNA表达分别与姜黄素10μmol／L组相比降低，差异有统计学意义（P〈0．01）；而姜黄素10μmol／L＋U012610μmol／L组、姜黄素10μmol／L＋U0126 20 μmol／L组HIF—1α蛋白、VEGF蛋白、mRNA表达分别与姜黄素10μmol／L组相比差异无统计学意义（P〉0.05）；不同浓度的姜黄素、LY294002 25 μmol／L处理的人肝癌细胞BEL-7402缺氧6h后磷酸化AKT蛋白表达逐渐降低，LY294002 25 μmol／L可以基本阻断磷酸化AKT蛋白的表达，而对总AKT蛋白表达无明显变化。结论姜黄素对人肝癌细胞BEL-7402中HIF-1α蛋白和VEGF的表达通过P13K／AKT／FRAP信号传导通路。     

1,25二羟维生素D3对肝癌HepG2细胞增殖侵袭影响

目的探讨1,25二羟维生素D3[1,25(OH)_2D_3]及PI3K/AKT信号通路抑制剂(LY294002)对人肝癌Hep G2细胞的增殖、侵袭影响及作用机制。方法实验设10~(-8)、10~(-7)、10~(-6)mol/L 1,25(OH)_2D_3组及2.5、5.0、10.0、20.0、40.0、80.0μmol/L LY294002组,10~(-7)mol/L 1,25(OH)_2D_3+5μmol/L LY294002联合组,噻唑蓝法检测人肝癌Hep G2细胞增殖抑制率;Compu Syn软件计算联合指数;Tanswell小室检测HepG2细胞侵袭数;Western blot检测Hep G2细胞增殖细胞核抗原(PCNA),细胞基质金属蛋白酶9(MMP-9)、磷酸化丝氨酸苏氨酸蛋白激酶(p-AKT)、10号染色体缺失且与张力蛋白同源物磷酸脂酶基因(PTEN)蛋白。结果 1,25(OH)_2D_3及LY294002对人肝癌HepG2细胞增殖抑制率呈时间-剂量依赖效应(P0.05);1,25(OH)2D3联合LY294002组细胞增殖抑制率明显高于二者单独处理组(P0.05),联合指数=0.728,2者具有协同效应;10-7mol/L 1,25(OH)2D3组、5μmol/L LY294002组以及联合组Hep G2细胞侵袭数[分别为(45.9±6.4)、(49.9±6.0)、(27.8±4.0)个]明显低于对照组[(64.6±8.0)个](P0.05)。与对照组比较,10-7mol/L 1,25(OH)2D3组及联合组HepG2细胞PTEN蛋白表达量增加,差异有统计学意义(P0.05),10-7mol/L 1,25(OH)_2D_3组、5μmol/L LY294002组及联合组HepG2细胞PCNA、MMP-9、p-AKT蛋白表达均降低,差异有统计学意义(P0.05),且联合组蛋白表达量低于二者单独处理组(P0.05)。结论 1,25(OH)_2D_3可抑制人肝癌HepG2细胞增殖、侵袭,其机制可能与上调PTEN表达,抑制PI3K/AKT信号通路活性,下调PCNA、M M P-9蛋白有关;与LY294002合用具有协同效应。     

表没食子儿茶素没食子酸酯对丙烯酰胺致小脑颗粒神经元氧化损伤的防护作用研究

目的探讨表没食子儿茶素没食子酸酯(EGCG)对丙烯酰胺(ACR)致小脑颗粒神经元(CGNs)损伤的保护作用。方法采用体外细胞培养的方法,建立ACR损伤CGNs的体外模型。经不同浓度EGCG(5、10、25、50、100 mol/L)预处理24h后,加入ACR(5 mmol/L)染毒,24 h后用四甲基偶氮唑盐(MTT)比色法检测细胞存活率,倒置显微镜下观察细胞形态学变化,测定细胞内超氧化物歧化酶(SOD)活性及丙二醛(MDA)的含量,Hochest 33342染色观察凋亡时细胞核形态的变化,末端脱氧核苷酸转移酶介导的原位缺口末端标记(TUNEL)法检测细胞凋亡指数。结果同ACR损伤组比较,终浓度为10、25、50 mol/L的EGCG能减轻ACR引起的CGNs损伤,可明显提高细胞的存活率(P<0.05),SOD活性增高,MDA含量降低(P<0.05),Hoechst33342染色和TUNEL荧光标记显示,细胞核固缩、致密浓染现象较ACR损伤模型组改善明显,凋亡指数下降(P<0.05),且呈现剂量依赖趋势,而终浓度为5、100 mol/L EGCG组较正常组无明显变化。结论 EGCG在一定剂量范围内对ACR氧化损伤的CGNs有防护作用。[营养学报,2012,34(4):362-367]     

表没食子儿茶素没食子酸酯对体外Aβ1-42诱导PC12细胞凋亡的保护机制研究

目的探讨表没食子儿茶素没食子酸酯(epigallocatechin-3-gallate,EGCG)对体外Aβ1-42诱导PC12细胞凋亡的保护作用及机制。方法 20μmol/L Aβ1-42诱导PC12细胞构建细胞损伤模型,设立对照组、模型组(20μmol/L Aβ1-42)、不同浓度EGCG干预组(5、10、20μmol/L EGCG+20μmol/L Aβ1-42)及VE阳性对照组(20μmol/L VE+20μmol/L Aβ1-42)。采用CCK-8法检测PC12细胞存活率,分别用Annexin V-FITC/PI法、DCFH-DA法、JC-1法检测细胞凋亡、ROS及线粒体膜电位,生化法检测细胞ATP含量。结果与对照组相比,模型组细胞存活率明显降低,线粒体膜电位及ATP含量显著降低,ROS水平增加,凋亡率升高。与模型组相比,3个EGCG干预组均可明显提高细胞存活率,降低细胞凋亡率;EGCG-M组及EGCG-H组可以降低ROS水平,提高线粒体膜电位,增加ATP含量,且EGCG-H组改变更显著。结论 EGCG可降低Aβ1-42诱导的PC12细胞凋亡,其机制可能与降低细胞ROS水平,提高线粒体膜电位及ATP含量有关。[营养学报,2020,42(2):173-177]     

邻苯二甲酸-单-乙基己基酯对原代培养新生大鼠海马神经元细胞活性和凋亡率的影响

目的探讨邻苯二甲酸-单-乙基己基酯[mono-(2-ethylhexyl)phthalate,MEHP]对新生大鼠海马神经元细胞活性和凋亡率的影响。方法取出生24 h内清洁级SD大鼠海马组织神经元原代培养8 d后,分别加入含终浓度0(溶剂对照)~100μmol/L MEHP的培养液暴露12、24 h。采用MTT法检测细胞活性,采用Hoechst 33258染色法检测神经元的凋亡情况。结果随着MEHP暴露剂量的升高,新生大鼠海马神经元的存活率、凋亡率均呈先上升后下降的趋势。结论 MEHP可抑制新生大鼠海马神经元细胞活性,促进神经元凋亡。提示MEHP对新生大鼠的海马神经元具有毒性作用。     

脑源性神经营养因子对皮质酮诱导新生大鼠海马神经元凋亡的保护作用

目的 探讨脑源性神经营养因子(brain-derived neurotrophic factor, BDNF)对皮质酮诱导新生大鼠海马神经元凋亡的保护作用。 方法 原代培养新生大鼠海马神经元,并分成对照组、皮质酮组、皮质酮+BDNF组,皮质酮造模浓度为100 μM,分别采用浓度为0.1、1、10、25、50、100 ng/ml的BDNF干预,造模及干预时间均为24 h。CCK8法测定细胞活力,分析BDNF的最佳作用浓度,流式细胞术和 Hoechst荧光染色检测细胞的凋亡情况,免疫印迹(Western-blotting)法检测细胞Caspase-3、Caspase-9的表达水平。 结果 与对照组比较,皮质酮组神经元凋亡率由(10.7±1.2)%上升为(33.9±3.5)%(t=18.707,P<0.01),胞体透亮,部分细胞核碎裂,凋亡特征明显,Caspase-3、Caspase-9表达显著上调(t₁=27.098,P₁＜0.01;t₂=24.311,P₂＜0.01);BDNF作用后,细胞活力显著上升,在浓度为1 ng/ml时与皮质酮组比较差异有统计学意义(t=3.562,P＜0.05),分析得出BDNF最佳浓度为48 ng/ml;BDNF(48 ng/ml)干预完成后,细胞凋亡率较皮质酮组下降至(18.7±2.1)%,差异有统计学意义(t=11.478,P＜0.01),细胞形态基本恢复正常,Caspase-3、Caspase-9表达明显下调(t₁=17.341,P₁=0.002;t₂=14.993,P₂=0.005)。 结论 BDNF能有效拮抗皮质酮诱导的海马神经元凋亡,保护神经元细胞。     

PI3K-AKT信号传导通路与鼻咽癌的相关性的初步研究

目的探讨鼻咽癌患者磷脂酰肌醇3-激酶/蛋白激酶B(PI3K—AKT)信号转导通路及其鼻咽癌细胞株(CNE2)之间的关系。方法按诊断标准选取我院门诊、健康体检和住院病人鼻咽癌患者研究组和空白对照组,各5例。比较2组鼻咽癌患者磷脂酰肌醇3-激酶/蛋白激酶B(PI3K—AKT)信号转导通路及其鼻咽癌细胞株(CNE2)的相关性。结果研究组和空白对照组的PI3K和AKT的蛋白表达量明显高于正常值。而LY294002对CNE2细胞生长、增殖具有抑制作用,而且呈剂量依赖性。LY294002作用后鼻咽癌细胞株CNE2细胞的PI3K和AKT的蛋白表达均减弱。LY294002可以诱导CNE2细胞的凋亡。随着LY294002浓度的增加,凋亡率呈上升趋势,15、30、50nmol/L的LY294002作用后CNE2细胞所产生的凋亡率分别为(5.621±0.125)、(18.522±0.764)、(24.270±0.215),而空白对照组为(3.430±0.234),差异有统计学意义(P<0.05)。结论 LY294002与鼻咽癌鼻咽癌细胞株CNE2间存在显著负相关,并可以抑制鼻咽癌鼻咽癌细胞株CNE2的生长和增殖从而诱导其凋亡。磷脂酰肌醇3-激酶/蛋白激酶B(PI3K—AKT)信号转导通路的激活及其鼻咽癌细胞株(CNE2)之间存在显著正相关关系。     

西红花酸对Aβ25-35诱导海马神经元损伤的神经保护作用

目的 探讨西红花酸对Aβ25-35诱导的SD大鼠海马神经元损伤的神经保护作用.方法 常规培养SD大鼠海马神经元,分为对照组、0.1μM西红花酸组、10μmol/L Aβ25-35组、0.01 μM西红花酸+10μmol/L Aβ25-35组、0.1μM西红花酸+10μmol/L Aβ25-35组、1μM西红花酸+10μmol/L Aβ25-35组;MTT检测细胞活力变化情况;荧光探针DCFH-DA检测细胞内ROS水平变化情况.结果 10μmol/L Aβ25-35显著降低细胞的活性和升高海马神经元ROS水平(P＜0.01);不同浓度西红花酸(0.01、0.1和1μM)预处理后,细胞活性分别比0A25-35组提高了39.2％、56.1％和76.4％,差异有显著性意义(P＜0.05),培养10天和25天海马神经元的ROS水平与Aβ25-35组比较均显著降低(P ＜0.01).结论 西红花酸对Aβ25-35诱导海马神经元的损伤具有保护作用,能显著降低Aβ25-35引起的海马神经元ROS水平的升高.     

磷脂酰肌醇3-激酶/蛋白激酶B信号转导通路在苯醌致HL-60细胞增殖过程中的作用

目的 探讨磷脂酰肌醇3-激酶/蛋白激酶B(PI3K/Akt)信号转导通路在苯醌(BQ)致HL-60细胞增殖中的作用.方法 取对数生长期的HL-60细胞,分为对照组(PBS处理细胞)、BQ染毒组(3 μmol/L BQ染毒)、LY294002+BQ染毒组(3μmol/L BQ染毒前加20 μmol/L LY294002),用alamar blue 法检测细胞增殖率,免疫印迹(Western blot)法检测细胞内p-Akt、Akt蛋白的表达,流式细胞仪检测细胞周期情况.结果 BQ染毒组细胞增殖率(185.00%±30.00%)和S、G2期细胞比例(分别为48.23%±1.37%、15.40%±1.21%)均高于对照组(分别为100.00%±0.00%、42.47%±0.45%、5.40%±0.40%),G1期细胞比例(36.37%±0.40%)低于对照组(52.13%±0.75%),差异均有统计学意义(P＜0.05);BQ染毒组细胞内p-Akt蛋白表达量明显高于对照组,差异有统计学意义(P<0.05),Akt表达量与对照组的差异无统计学意义(P＞0.05).LY294002+BQ染毒组细胞增殖率(82.59%±15.00%)和S、G2期细胞比例(分别为42.03%±0.50%、3.87%±0.47%)比BQ染毒组低,G1期细胞比例(54.43%±0.40%)比BQ染毒组高,差异均有统计学意义(P<0.05),细胞内p-Akt蛋白表达量明显低于BQ染毒组,差异有统计学意义(P<0.05);Akt蛋白表达量与BQ染毒组的差异无统计学意义(P>0.05).结论 PI3K/Akt信号转导通路在BQ致HL-60细胞增殖过程中可能起着重要作用.

Abstract：

Objective To explore the effects of phosphatidylinositol 3-kinase/ Serine-threonine kinase (PI3K/Akt) signal pathway on the proliferation of HL-60 cells exposed to benzoquinone (BQ). Methods HL-60 cells were divided into 3 groups: control group (treated with PBS), BQ group (treated with 3 μmol/L BQ) and LY294002 plus BQ group (treated with 20 μmol/L LY294002 plus 3 μmol/L BQ). The cell proliferation was measured with alamar blue dye assay. Western blot assay was used to detect the expression of p-Akt and Akt proteins and flow cytometer was used to observe the cell cycle. Results The cell proliferation rate and the cell proportion in the S, G2 phase of BQ group were 185.00%±30.00%, 48.23%±1.37% and 15.40%±1.21%, respectively, which were significantly higher than those ( 100.00%±0.00%, 42.47%±0.45% and 5.40%±0.40%) of control group (P<0.05 ). But the cell proportion rate (36.37%±0.40% ) in the G1 phase in BQ group was significantly lower than that (52.13%±0.75% ) in control group (P<0.05). The expression level of p-Akt protein in BQ group was significantly higher than that in control group (P<0.05). The cell proliferation rate and the cell proportion in the S, G2 phase of LY294002 plus BQ group were 82.59%±15.00%, 42.03%±0.50% and 3.87%± 0.47%, respectively, which were significantly lower than those of BQ group (P<0.05). But the cell proportion rate (54.43%±0.40%) in the G1 phase in LY294002 plus BQ group was significantly higher than that in BQ group (P<0.05 ). Conclusion The PI3K/Akt signal pathway may play an important role in the proliferation of HL-60 cells exposed to BQ.     

Epigallocatechin gallate stimulates glucose uptake through the phosphatidylinositol 3-kinase-mediated pathway in L6 rat skeletal muscle cells

The effect of epigallocatechin gallate (EGCG) on glucose uptake was studied in L6 rat skeletal muscle cells. Glucose uptake assay revealed that EGCG increased glucose uptake >70% compared to control. EGCG-stimulated glucose uptake was blocked by LY294002, an inhibitor of phosphatidylinositol (PI) 3-kinase, which is a major regulatory molecule in glucose uptake pathways. However, AMP-activated protein kinase (AMPK), which is another crucial mediator in independent glucose uptake pathways, did not inhibit EGCG-stimulated glucose uptake by SB203585, a specific inhibitor of the AMPK downstream mediator, p38 mitogen-activated protein kinase (MAPK). We also found that EGCG increased the phosphorylation level of protein kinase B and PI 3-kinase activity, when assessed by PI 3-kinase assay, whereas no increase in the phosphorylation level of AMPK and p38 MAPK was observed. Taken together, these results suggest that EGCG might stimulate glucose uptake, not AMPK-mediated but PI 3-kinase-mediated, in skeletal muscle cells, thereby contributing to glucose homeostasis.     

莱菔硫烷对膀胱癌细胞增殖抑制作用

目的研究丝裂原活化蛋白激酶(MAPKs)和磷脂酰肌醇激酶(PI3K)信号途径在莱菔硫烷(sulforaphane,SFN)抑制膀胱癌细胞增殖中的作用。方法噻唑蓝(MTT)法测定膀胱癌细胞的增殖作用,用实时定量PCR方法(re-al time-PCR)测定对环氧化酶(COX-2)mRNA的影响。结果 5～20μmol/L莱菔硫烷能明显抑制膀胱癌细胞的体外增殖、COX-2 mRNA表达;SB202190或LY294002预处理T24细胞,能明显降低莱菔硫烷对T24细胞增殖的抑制作用,提高细胞存活率;SB202190预处理T24细胞1h能完全阻断莱菔硫烷对COX-2 mRNA的抑制作用,而LY294002不影响莱菔硫烷对COX-2 mRNA的抑制作用。结论莱菔硫烷可能是通过活化p38激酶途径和PI3K激酶途径抑制膀胱癌细胞生长,p38激酶信号途径在SFN抑制COX-2 mRNA中起关键作用。     

雌马酚对人卵巢癌SKOV-3细胞增殖的抑制作用及其机制研究

目的观察雌马酚(equol)对人卵巢癌SKOV-3细胞增殖的抑制作用,并探讨其作用的分子机制。方法用不同浓度(10-8、10-7、10-6、10-5、5×10-5、10-4mol/L)雌马酚处理SKOV-3细胞24、48、72h后,及同时用10μmol/LERK通路抑制剂U0126或雌激素受体抑制剂ICI182,780处理1h后再用50μmol/L雌马酚处理2h,测定各组SKOV-3细胞存活率,用Westernblotting检测总ERK和磷酸化ERK1/2(p-ERK)的蛋白表达水平。结果各实验组SKOV-3细胞存活率随着雌马酚作用浓度和时间的增加而降低,总ERK蛋白表达量不变,p-ERK的表达量随雌马酚处理浓度的增加而逐渐降低。U0126、ICI182,780单独使用或与雌马酚联合使用均能够降低p-ERK的蛋白表达。结论雌马酚显著抑制人卵巢癌SKOV-3细胞的增殖,其机制是通过下调磷酸化ERK蛋白的表达发挥作用。     

Insulin-like growth factor-1 attenuates apoptosis and protects neurochemical phenotypes of dorsal root ganglion neurons with paclitaxel-induced neurotoxicity in vitro

Paclitaxel (PT)-induced neurotoxicity is a significant problem associated with successful treatment of cancers. Insulin-like growth factor-1 (IGF-1) is a neurotrophic factor and plays an important role in promoting axonal growth from dorsal root ganglion (DRG) neurons. Whether IGF-1 has protective effects on neurite growth, cell viability, neuronal apoptosis and neuronal phenotypes in DRG neurons with PT-induced neurotoxicity is still unclear. In this study, primary cultured rat DRG neurons were used to assess the effects of IGF-1 on DRG neurons with PT-induced neurotoxicity. The results showed that PT exposure caused neurite retraction in a dose-dependent manner. PT exposure caused a decrease of cell viability and an increase in the ratio of apoptotic cells which could be reversed by IGF-1. The percentage of calcitonin gene-related peptide immunoreactive (CGRP-IR) neurons and neurofilament (NF)-200-IR neurons, mRNA, and protein levels of CGRP and NF-200 decreased significantly after treatment with PT. IGF-1 administration had protective effects on CGRP-IR neurons, but not on NF-200-IR neurons. Either extracellular signal-regulated protein kinase (ERK1/2) inhibitor PD98059 or phosphatidylinositol 3-kinase (PI3 K) inhibitor LY294002 blocked the effect of IGF-1. The results imply that IGF-1 may attenuate apoptosis to improve neuronal cell viability and promote neurite growth of DRG neurons with PT-induced neurotoxicity. Moreover, these results support an important neuroprotective role of exogenous IGF-1 on distinct subpopulations of DRG neurons which is responsible for skin sensation. The effects of IGF-1 might be through ERK1/2 or PI3 K/Akt signaling pathways. These findings provide experimental evidence for IGF-1 administration to alleviate neurotoxicity of distinct subpopulations of DRG neurons induced by PT.     

Quercetin Decreases Claudin-2 Expression Mediated by Up-Regulation of microRNA miR-16 in Lung Adenocarcinoma A549 Cells

Claudin-2 is highly expressed in human lung adenocarcinoma tissues and cells. Knockdown of claudin-2 decreases cell proliferation and migration. Claudin-2 may be a novel target for lung adenocarcinoma. However, there are no physiologically active substances of foods which decrease claudin-2 expression. We here found that quercetin, a flavonoid present in fruits and vegetables, time- and concentration-dependently decreases claudin-2 expression in lung adenocarcinoma A549 cells. In the present study, we examined what regulatory mechanism is involved in the decrease in claudin-2 expression by quercetin. Claudin-2 expression was decreased by LY-294002, a phosphatidylinositol 3-kinase (PI3-K) inhibitor, and U0126, a MEK inhibitor. These drugs inhibited the phosphorylation of Akt and ERK1/2, which are downstream targets of PI3-K and MEK, respectively. In contrast, quercetin did not inhibit the phosphorylation. Both LY-294002 and U0126 inhibited promoter activity of claudin-2, but quercetin did not. The stability of claudin-2 mRNA was decreased by quercetin. Quercetin increased the expression of microRNA miR-16. An inhibitor of miR-16 rescued quercetin-induced decrease in the claudin-2 expression. These results suggest that quercetin decreases claudin-2 expression mediated by up-regulation of miR-16 expression and instability of claudin-2 mRNA in lung adenocarcinoma cells.     

磷酸酰肌醇-3激酶抑制剂对小鼠气道炎症影响的实验研究

目的观察磷酸酰肌醇-3激酶(PI3K)抑制剂LY294002对卵白蛋白(OVA)诱导哮喘小鼠气道炎症的影响。方法Balb/c小鼠30只,随机分为三组,每组10只:PI3K抑制剂治疗组(LY组),OVA组和正常对照组(NC组)。通过OVA多次腹腔注射致敏和反复雾化激发,建立哮喘小鼠模型。末次抗原激发后48h收集支气管肺泡灌洗液(BALF)和骨髓标本,计数细胞总数和嗜酸性粒细胞(Eos),并行肺组织学检查。结果与OVA组比较,LY组BALF中细胞总数及Eos绝对数明显减少(p<0.05);肺组织中细支气管、血管周围Eos浸润得到控制,气道粘液分泌减少。结论PI3K抑制剂(LY294002)对卵白蛋白(OVA)致敏的哮喘小鼠气道炎症具有抑制作用。