胰岛素通过PI3K/AKT/GSK3通路促多囊卵巢综合征患者子宫内膜病变机制的研究

目的 研究多囊卵巢综合征(PCOS)胰岛素抵抗(IR)与非抵抗患者子宫内膜的PI3 K/AKT/GSK3信号通路蛋白表达情况;探讨胰岛素在PCOS患者子宫内膜病变的作用机制.方法 以2006年3月至2010年5月北京天坛医院妇产科门诊治疗的34例PCOS患者为实验组,以同期因输卵管因素不孕行诊刮术的非PCOS患者30例为对照组.实验组患者行OGTT、INS实验及性腺6项测定,根据是否存在IR将PCOS患者分为Ⅰ组(IR组)和Ⅱ组(非IR组).对实验组和对照组患者子宫内膜石蜡标本应用免疫组化方法测定PI3K(磷脂酰肌醇-3激酶)、p-AKT(PPKB,磷酸化蛋白激酶B)、GSK3(糖原合成酶激3)的表达.结果 PCOS患者的PDK表达水平要明显高于对照组(P=0.000,0.003),其中PCOS Ⅰ组最高(P=0.022).在p-AKT表达上,PCOS患者要明显高于对照组(P=0.011,0.000),其中以PCOS Ⅰ组最高(P =0.002),而在GSK3表达上,PCOS Ⅰ组,Ⅱ组和对照组三组之间差异无统计学意义(P＞0.05).结论胰岛素信号通路PI3K、p-AKT可能是IR PCOS患者子宫内膜病变的信号转导通路.     

骨化三醇通过PI3K/AKT促进BMP9诱导的间充质干细胞成骨分化作用

目的研究骨化三醇(calcitriol)对骨形态发生蛋白9(bone morphogenetic protein 9,BMP9)诱导的间充质干细胞(mesenchymal stem cells,MSCs)成骨分化作用的影响。方法实验分为4组:对照组、calcitriol组、BMP9组、calcitriol联合BMP9组。通过PNPP法检测各组碱性磷酸酶(alkaline phosphatase,ALP)活性;通过RT-PCR和Western blotting方法检测成骨分化标记物骨钙蛋白(osteocalcin,OCN)和骨桥蛋白(osteopontin,OPN)表达变化,同时检测AKT和β-catenin磷酸化水平以及和ALP活性水平;茜素红染色检测矿化结节形成。此外,用原子力显微镜测试MSCs成骨分化过程中细胞形态及细胞弹性模量改变。结果 calcitriol单独作用对MSCs成骨分化过程无明显作用,但是calcitriol可以增强BMP9诱导MSCs的ALP、OCN、OPN表达和矿化结节形成。同时,calcitriol和BMP9作用均不影响细胞弹性模量数值。BMP9和calcitriol联合作用可以增强AKT和β-catenin磷酸化水平,而PI3K抑制剂应用以后可以抑制这种磷酸化变化,并抑制联合作用后的ALP活性。calcitriol作用以后不影响BMP9诱导的BMP/Smad信号通路。结论 calcitriol通过激活PI3K/AKT信号通路从而协同BMP9促进MSCs成骨分化。研究不同调控因子对MSCs成骨分化的作用及机制对于骨质疏松等疾病的治疗和骨组织工程的发展有一定意义。     

Interleukin-1 Beta Increases Activity of Human Endothelial Progenitor Cells: Involvement of PI3K-Akt Signaling Pathway

Interleukin-1β (IL-1β) is a multifunctional proinflammatory cytokine upregulated in acute phase of heart ischemic disease. Controversial effects of IL-1β have been demonstrated on endothelial progenitor cells (EPCs) functional activity. The aim of this study was to investigate the in vitro effect of IL-1β on activity of human origin EPCs and the possible mechanism involved. EPCs were isolated from peripheral blood of healthy volunteers without cardiovascular risk factors and characterized. After ex vivo cultivation, EPCs were stimulated with a series of final concentrations (0, 0.1, 1, and 10 ng/ml) of IL-1β for 24 h. In some other experiments, EPCs were pretreated with 10 μM LY294002 (Akt inhibitor) for 30 min and then stimulated with 1 ng/ml IL-1β for 24 h. Cell proliferation, apoptosis, adhesion, and migration were determined, respectively, by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, annexin V/propidium iodide binding assay, adhesion assay, and transwell migration assay. In addition, the vascular endothelial vascular growth factor-A (VEGF-A) production has been examined using quantitative real-time RT-PCR and ELISA assay. Furthermore, the total and phosphorylation level of Akt was determined by Western blot. IL-1β significantly stimulated EPC proliferation, migration, and adhesion and upregulated the angiogenic growth factor VEGF-A at mRNA and protein level, while exerted no influence on cell apoptosis. However, pretreatment with LY294002 significantly diminished IL-1β-induced proliferation, migration, adhesion, and VEGF-A production. One nanogram per milliliter IL-1β for 15 min activated phosphorylation of Akt. These results suggest a potent role for IL-1β in upregulating EPCs functions. The phosphatidyl-inositol-3-kinase-Akt signaling pathway could be involved in the regulation of EPCs functions induced by IL-1β.     

Regulation of Antioxidants and Phase 2 Enzymes by Shear-Induced Reactive Oxygen Species in Endothelial Cells

Exposure of vascular endothelial cells (ECs) to steady laminar shear stress activates the NF-E2-related factor 2 (Nrf2) which binds to the antioxidant response element (ARE) and upregulates the expression of several genes. The onset of shear is known to increase the EC reactive oxygen species (ROS) production, and oxidative stress can activate the ARE. ARE-regulated genes include phase 2 enzymes, such as glutathione-S-transferase (GST) and NAD(P)H:quinone oxidoreductase 1 (NQO1), and antioxidants, such as glutathione reductase (GR), glutathione peroxidase (GPx) and catalase. We examined how shear stress affects the antioxidant/phase 2 enzyme activities and whether ROS mediate these effects. ROS production, measured by dichlorofluorescin fluorescence, depended on level and time of shear exposure and EC origin, and was inhibited by either an endothelial nitric oxide synthase (eNOS) inhibitor or a superoxide dismutase (SOD) mimetic and peroxynitrite (ONOO⁻) scavenger. Shear stress (10 dynes/cm², 16 h) significantly increased the NQO1 activity, did not change significantly the glutathione (GSH) content, and significantly decreased the GR, GPx, GST and catalase activities in human umbilical vein ECs. Either eNOS inhibition or superoxide radical (O₂^•−)/ONOO⁻ scavenging differentially modulated the shear effects on enzyme activities suggesting that the intracellular redox status coordinates the shear-induced expression of cytoprotective genes.     

Involvement of Heme Oxygenase-1 in Kaempferol-Induced Anti-Allergic Actions in RBL-2H3 Cells

Kaempferol is one of the most commonly found dietary flavonoids. The exposure to kaempferol is known to inhibit degranulation from mast cells, but the inhibitory mechanism of degranulation has not been clarified yet. In this study, we investigated the involvement of heme oxygenase (HO)-1 in the anti-allergic action of kaempferol against degranulation in rat basophilic leukemia (RBL-2H3) cells. Our results demonstrate upregulation of HO enzymatic activity after short (15 min) exposure to kaempferol, followed by the induction of HO-1 expression in protein. The involvement of HO-1 in the kaempferol-induced inhibition of degranulation was confirmed using tin protoporphyrin IX (SnPP), a HO-1 inhibitor. These findings strongly suggest that kaempferol exerts anti-allergic actions via activation of the HO-1. Etsuko Hirose and Miyoko Matsushima have contributed equally to this work.     

Mycoplasma fermentans MALP-2 Induces Heme Oxygenase-1 Expression via Mitogen-Activated Protein Kinases and Nrf2 Pathways To Modulate Cyclooxygenase 2 Expression in Human Monocytes

Heme oxygenase-1 (HO-1) is a stress-inducible rate-limiting enzyme in heme degradation that confers cytoprotection against oxidative injury and performs a vital function in the maintenance of cell hemostasis. Increasing numbers of reports have indicated that mycoplasma-derived membrane lipoproteins/lipopeptides, such as macrophage-activating lipopeptide-2 (MALP-2), function as agents that stimulate the immune system by producing various inflammatory mediators, such as cytokines and cyclooxygenase 2 (COX-2), which play roles in the pathogenesis of inflammatory responses during mycoplasma infection. Here, we report that MALP-2 induced HO-1 mRNA and protein expression and upregulated HO-1 enzyme activity in THP-1 cells. Specific inhibitors of mitogen-activated protein kinases (MAPKs), SB203580, PD98059, and SP600125, significantly abolished HO-1 expression. In addition, MALP-2 also induced NF-E2-related factor 2 (Nrf2) translocation, and the silencing of Nrf2 expression in THP-1 cells decreased the levels of MALP-2-mediated HO-1 expression. Furthermore, COX-2 protein expression levels were upregulated in THP-1 cells in response to MALP-2, and transfection with small interfering RNAs of HO-1 significantly increased COX-2 accumulation. These results demonstrate that MALP-2 induces HO-1 expression via MAPKs and Nrf2 pathways and, furthermore, that MALP-2-induced COX-2 expression was modulated by HO-1 in THP-1 cells.     

Alkaline ceramidase 3 promotes growth of hepatocellular carcinoma cells via regulating S1P/S1PR2/PI3K/AKT signaling

Objective

Hepatocellular carcinoma (HCC) is one of the cancer types with poor prognosis. To effectively treat HCC, new molecular targets and therapeutic approaches must be identified. Alkaline ceramidase 3 (Acer3) hydrolyzed long-chain unsaturated ceramide to produce free fatty acids and sphingosine. However, whether and how Acer3 modulates progression of HCC remains largely unknown.

miR-296-5p 靶向 PLK1 调控 PI3K/ AKT 通路诱导骨肉瘤细胞中的自噬并抑制上皮-间质转化

目的 探讨 miR-296-5p 靶向 PLK1 对骨肉瘤 (osteosarcoma, OS) 细胞自噬及抑制上皮-间质转化 (EMT) 的作用机制。 方法 qRT-PCR 检测 miR-296-5p 在 OS 细胞中的表达。 采用生物信息学分析预测 miR-296-5p 的靶基因, 验证 miR-296-5p 对靶基因 PLK1 的直接靶向调控; 细胞转染构建 miR-296-5p 过表达 和干扰细胞, CCK-8、 克隆形成、 Transwell 小室、 流式、 蛋白免疫印迹实验检测 miR-296-5p 的不同表达对 U2OS 细胞中 PTBP1 表达水平及细胞增殖、 侵袭、 凋亡、 自噬及 EMT 的影响。 结果 与对照组比较, miR-296-5p 在 OS 中表达降低, 而 PLK1 则升高 (P< 0. 05); 与 miR-NC 组比较, mimic 组的克隆形成率、 侵袭 细胞数目及 PTBP1、 p62、 N-cadherin、 Vimentin、 p-PI3K/ PI3K、 p-AKT/ AKT 水平降低, 细胞凋亡率、 Beclin-1、 LC3-Ⅱ/ Ⅰ、 E-cadherin 水平升高 (P< 0. 05); 与 PLK1 组比较, PLK1 + mimic 组的克隆形成率、 侵袭 细胞数目及 PTBP1、 p62、 N-cadherin、 Vimentin、 p-PI3K/ PI3K、 p-AKT/ AKT 水平降低, 细胞凋亡率、 Beclin-1、 LC3-Ⅱ/ Ⅰ、 E-cadherin 水平升高 (P< 0. 05)。 结论 miR-296-5p 可能能够靶向 PLK1 调控 PI3K/ AKT 通路诱导 OS 细胞中的自噬并抑制 EMT。     

PI3K/AKT inhibition induces caspase-dependent apoptosis in HTLV-1-transformed cells

The phosphatidylinositol-3-kinase (PI3K) and AKT (protein kinase B) signaling pathways play an important role in regulating cell cycle progression and cell survival. In previous studies, we demonstrated that AKT is activated in HTLV-1-transformed cells and that Tax activation of AKT is linked to p53 inhibition and cell survival. In the present study, we extend these observations to identify regulatory pathways affected by AKT in HTLV-1-transformed cells. We demonstrate that inhibition of AKT reduces the level of phosphorylated Bad, an important member of the pro-apoptotic family of proteins. Consistent with the decrease of phosphorylated Bad, cytochrome c is released from the mitochondria and caspase-9 is activated. Pretreatment of the cells with caspase-9 specific inhibitor z-LEHD-FMK or pan caspase inhibitor Ac-DEVD-CHO prevented LY294002-induced apoptosis. Of interest, p53 siRNA prevents LY294002-induced apoptosis in HTLV-1-transformed cells, suggesting that p53 reactivation is linked to apoptosis. In conclusion, the AKT pathway is involved in targeting multiple proteins which regulate caspase- and p53-dependent apoptosis in HTLV-1-transformed cells. Since AKT inhibitors simultaneously inhibit NF-kappaB and activate p53, these drugs should be promising candidates for HTLV-1-associated cancer therapy.     

Endothelial Cells Promote Anti-CD3-Induced T-cell Proliferation via Cell-Cell Contact Mediated by LFA-1 and CD2

T-cell activation requires not only T-cell receptor (TCR) engagement and subsequent TCR/CD3 cross-linking, but also one or more secondary activation signals generated by accessory cells (AC). We investigated the accessory function endothelial cells (EC) in an in vitro model for T-cell activation where the first cross-linking signal was delivered to peripheral human T lymphocytes by cither immobilized anti-CD3 monoclonal antibody (MoAb) or by PHA. In a previous report, we showed that EC provided a potent costimulatory signal in this model system. We have now analysed the nature of the EC-derived costirnulatory signal by testing whether EC could be substituted by cy lokines. by studying the effect of EC fixation and by testing the involvement of a number of adhesion molecules. Our findings indicate that EC accessory function is mediated mainly by membrane-bound factors. The nature of these membrane-bound factors was analysed by studying the inhibitory properties of a series of MoAbs directed against several adhesion molecules. Antibodies directed against CD44, E-selectin, CD31, CD26, B7/BBI, VLA-4 or VCAM-1 were not inhibitory. However, an inhibition, was clearly observed with antibodies against LFA-1 and CD2. Remarkably, this inhibition was not found with MoAbs to their respective counterstructures ICAM-1 and LFA-3. In summary, we postulate that both LFA-l/ICAM-1, and CD2 LFA-3 interactions are involved in EC accessory function, although the role of the EC-associated adhesion partners is not fully understood.     

Modulatory role of garlicin in migration and invasion of intrahepatic cholangiocarcinoma via PI3K/AKT pathway

Increasing evidences have indicated the role of garlicin in inhibiting the progression of various tumors including glioma, pulmonary carcinoma and pancreatic carcinoma, via mediating cell apoptosis or cell cycle. The regulatory effect and related molecular mechanism of garlicin in intrahepatic cholangiocarcinoma, however, remained unknown. This study thus aimed to investigate this scientific issue. HCCC-9810 cell line was treated with serially diluted garlicin, followed by cell proliferation assay using MTT approach. Transwell migration and invasion assays were further employed the regulatory effect of garlicin. The expression level of p-AKT and AKT proteins in tumor cells was quantified by Western blot. The growth of tumor cells was significantly inhibited by high concentration of garlicin (> 1.5 μM). Lower concentration of garlicin showed dose-dependent inhibition of tumor cell invasion and migration. After using specific agonist IGF-1 (50 ng/mL) of PI3K/AKT signaling pathway, such facilitating effects of garlicin were depressed (P < 0.05). Western blotting showed significantly decreased phosphorylation level of AKT after treated with gradient concentrations of garlicin, while leaving the total AKT protein level unchanged. Garlicin may inhibit the invasion and migration of intrahepatic cholangiocarcinoma cells via inhibiting PI3K/AKT signaling pathway.     

杜仲绿原酸通过PI3K/AKT/Nrf-2通路增强视网膜母细胞瘤细胞系HXO-Rb44放射敏感性

目的　探究杜仲绿原酸（CGA）通过调控PI3K/AKT/Nrf-2通路,对视网膜母细胞瘤细胞系HXO-Rb44放射敏感性的增强作用。 方法　通过不同浓度的CGA处理HXO-Rb44细胞,检测IC10,作为后续实验中CGA浓度。将细胞分为Ctrl、Radio、CGA、Radio+CGA组,Radio组给予4 MV X射线照射24 h,CGA组使用CGA处理24 h,Radio+CGA组在CGA处理24 h后再给予4 MV X射线照射24 h,流式细胞术检测细胞周期与细胞凋亡,蛋白质印迹检测Ki67、依赖还原型辅酶I/II醌氧化还原酶I（NQO1）、活化型半胱天冬酶（cl-caspase-3）、硫氧还蛋白还原酶1（TrxR1）、活化磷脂酰肌醇3-激酶（p-PI3K）、蛋白激酶B（AKT）、p-AKT、核因子E2相关因子2（Nrf2）蛋白表达。进一步通过PI3K激活剂740Y-P处理细胞,检测细胞周期、凋亡、增殖和相关蛋白表达、PI3K/AKT/Nrf2通路蛋白表达。 结果　随着CGA浓度的增高,细胞的相对存活率降低,药物毒性呈浓度依赖性,IC10为81.59 μmol/L。与Ctrl组相比,Radio和CGA组G2/M期细胞比例显著升高,细胞凋亡比率显著升高（P<0.01）;与Radio组相比,Radio+CGA组G2/M期细胞比例和细胞凋亡比率进一步显著升高（P<0.01）。同时在蛋白水平上,与Ctrl组相比,Radio和CGA组Ki67、NQO1、TrxR1、p-PI3K、Nrf2蛋白表达及p-AKT/AKT比率显著降低（P<0.01）;放射和CGA联合作用进一步降低以上各指标（P<0.01）。此外,PI3K激活剂可逆转放射对细胞周期、增殖、凋亡以及PI3K/AKT/Nrf2通路的作用,CGA可恢复放射引起的上述各指标的变化（P<0.01）。 结论　CGA可增强HXO-Rb44细胞的放射敏感性,其作用机制与抑制PI3K/AKT/Nrf2通路相关。     

ERK1/2信号转导途径在低切应力上调人脐静脉内皮细胞IL-8基因表达中的作用

血管内皮细胞位于血流和血管壁之间,除受化学因素的调节外还受力学因素的影响。切应力可通过刺激相应的力学感受系统来调节内皮细胞某些基因的表达,其中包括诱导内皮细胞表达IL- 8。为了阐明MAPK信号途径中的ERK1/ 2信号通路是否参与调控低切应力上调人脐静脉内皮细胞IL- 8基因表达,采用Western blot分析了低切应力(4.2 0 dyne/ cm2 )处理不同时间内皮细胞ERK1/ 2的磷酸化水平及TPK抑制剂Genistein,MEK抑制剂PD980 5 9对其磷酸化的影响;采用定量RT- PCR检测内皮细胞经低切应力刺激或给予阻断剂后再行切应力刺激等处理后IL- 8基因的表达。结果显示:(1)低切应力处理可引起内皮细胞ERK1/ 2蛋白磷酸化水平上调,其磷酸化水平与切应力作用时间有关,具有快速、双向性的特点(在刺激10 min时达到高峰,2 h左右降至未刺激水平) ,阻断剂Genistein和PD980 5 9处理后,ERK1/ 2磷酸化水平与低切应力刺激10 min比较明显降低;(2 )阻断剂Genistein,PD980 5 9可显著抑制低切应力所致的内皮细胞IL- 8m RNA上调。结果表明低切应力可通过ERK1/ 2信号途径上调人脐静脉内皮细胞IL- 8基因的表达。     

1-磷酸鞘氨醇受体2介导PI3K/AKT/eNOS通路抑制甲型流感病毒诱导的病毒性肺炎

目的:探讨1-磷酸鞘氨醇受体2(S1PR2)对甲型流感病毒诱导的病毒性肺炎的作用及机制。方法:采用甲型流感病毒鼠肺适应株FM1滴鼻感染野生C57BL/6小鼠和S1pr2~(-/-)小鼠,建立甲型流感病毒性肺炎动物模型。病毒感染4和6 d时观察比较对照组(模型组的野生小鼠)、JTE-013(S1PR2高效拮抗剂)处理的小鼠及S1pr2~(-/-)小鼠肺组织的病理改变,检测支气管肺泡灌洗液(BALF)中的蛋白浓度、细胞总数及细胞因子[白细胞介素(IL)-1β、IL-6和肿瘤坏死因子α(TNF-α)]的表达,Western blot法检测小鼠肺组织的AKT和e NOS的磷酸化水平。结果:与模型对照组的野生鼠比较,JTE处理组和S1pr2~(-/-)组甲型流感病毒性肺炎更加严重;BALF中的蛋白浓度,总细胞数及炎性细胞因子表达显著增加;且PI3K下游靶点AKT和e NOS磷酸化显著增高(P0.01)。结论:S1PR2通过介导PI3K/AKT/e NOS信号转导通路,调节NO生成,抑制血管通透性和炎性细胞因子释放,从而减轻甲型流感病毒诱导的病毒性肺炎。     

Prostaglandin transporter,SLCO2A1, mediates the invasion and apoptosis of lung cancer cells via PI3K/AKT/mTOR pathway

Treatment of lung cancer involves regulation of various key factors in many signaling pathways. The prostaglandin transporter, solute carrier organic anion transporter family member 2A1 (SLCO2A1), is a promising regulatory factor of cancer cells. By analyzing the invasion and apoptosis status of lung cancer cells, and detecting the expression changes of key factors in PI3K/AKT/mTOR pathway after overexpression and knockdown of SLCO2A1 in vitro, this study intended to investigate the function of SLCO2A1 in mediating lung cancer cells. Results showed overexpression of SLCO2A1 could induce the invasion of lung cancer cells, and its knockdown inhibited the invasion and induced the apoptosis of cells. mTOR, AKT and S6 in PI3K/AKT/mTOR pathway were not affected by SLCO2A1. But the expression levels of p-mTOR, p-AKT and p-S6 were up-regulated or down-regulated with the overexpression or knockdown of SLCO2A1. Thus SLCO2A1 was inferred to mediate the invasion and apoptosis of lung cancer cells via PI3K/AKT/mTOR pathway. These results implied SLCO2A1 could be a regulatory factor of the invasion and apoptosis of lung cancer cells and serve as a promising target for lung cancer therapy.