砷对人胶质瘤细胞周期调控相关基因表达的影响

目的比较三氧化二砷（As2O3）对两种不同p53表型胶质瘤细胞U87MG、T98G细胞周期调控相关基因表达的影响。方法应用功能分类细胞周期基因芯片技术，筛选出As2O3作用于两种胶质瘤细胞U87MG、T98G后与细胞周期调控表达有差异的基因，并对3条有共性表达的基因进行Western印迹分析；四甲基偶氮唑蓝（MTT）法检测细胞生长抑制率；流式细胞仪分析细胞周期改变。结果MTT分析表明：As2O2对2个细胞系的生长有抑制作用，且抑制率具有浓度和时间的依赖性，砷作用72h后，U87MG和T98G细胞系的生长抑制率为50％（IC50）时，其浓度分别为1．78、3．55μmol／L。As2O3可以将U87MG和T98G细胞周期阻滞于G0／G1和G2／M期。U87MG细胞在加入As2O3后，差异表达2倍以上的基因共11条，表达上调的有5条，下调的有6条。T98G细胞在加入As2O3后，差异表达的基因共13条，表达上调的有9条，下调的有4条。Western分析显示，As2O3能上调2个胶质瘤细胞系的P53蛋白水平，同时降低细胞周期蛋白B1、D1表达。结论As2O3通过将细胞周期阻滞于G0／G1和G2／M期来抑制U87MG和T98G细胞的增殖；p53、CyclinB、CylinD等基因表达与As2O3诱导胶质瘤细胞周期阻滞的发生有关。     

复方苦参注射液体外诱导鼻咽癌CNE2细胞凋亡的作用及机制

目的探讨复方苦参注射液对人鼻咽癌CNE2细胞的体外抑制作用。方法采用流式细胞仪分析复方苦参注射液对CNE2细胞周期的影响；利用RT—PCR技术检测细胞周期相关基因CyclinB2、Cdc6的表达情况。结果复方苦参注射液可抑制CNE2细胞增殖，诱导其凋亡，改变细胞周期分布，使G0-G1期CNE2细胞比例增高，同时还可使CyclinB2表达下降，Cdc6表达上调（P〈0．05或〈O．01）。上述作用具有剂量依赖性。结论复方苦参注射液可能通过阻滞细胞周期、降低CyclinB：蛋白、上调Cdc6的基因表达来发挥其抗肿瘤作用。     

抑制HSP70—2基因表达诱导肝癌细胞G2／M期阻滞的机制研究

目的探讨HSP70—2在肝癌组织中的表达，以及抑制HSP70—2表达对肝癌细胞生长和周期影响的详细作用机制。方法免疫组织化学检测HSP70—2在45例肝癌组织和癌旁组织中的表达，Westernblot检测HSP70—2在5种肝癌细胞株中的表达。设计合成针对HSP70—2基因的特异性shRNA，构建真核表达载体HSP70-2shRNA1和HSP70—2shRNA2。转染肝癌细胞后，MTT法检测细胞增殖，流式细胞仪检测细胞周期，Westernblot检测HSP70—2表达及细胞周期相关蛋白p-Cdc2（Tyr15）、Cdc25C、Cdc2和cyclinB1的表达变化。结果免疫组织化学检测显示，45例肝癌组织中有33例（73．3％）HSP70—2蛋白表达阳性，45例癌旁组织中仅4例（8．9％）表达阳性，表达差异有显著性（P〈0．05）。HSP70—2蛋白在HepG2、Bel-402、Huh-7、Hep3B、SMMC-7721肝癌细胞中的表达明显高于其在L02细胞中的表达。HSP70—2shRNA1和shRNA2均能有效抑制肝癌细胞HepG2和Bel-7402中HSP70-2的表达。与controlshRNA组相比，转染HSP70-2shRNA1和shRNA2组HepG2和Bel-7402细胞生长增殖速度均明显减慢，细胞周期表现为处于G1／M期的细胞比例显著增加。Westernblot检测发现，转染HSP70-2shRNA1和shRNA2后肝癌细胞中磷酸化的p-Cdc2（Tyr15）表达增加，Cdc25C、Cdc2和cyclinB1表达显著减少。结论HSPT0-2在肝癌中过表达，抑制HSP70．2表达可以显著抑制肝癌细胞的增殖，诱导细胞周期阻滞，其诱导G，／M期阻滞的机制是通过影响Cdc25C-Cdc2／cyclinB1通路来实现的。     

NF-kB、Ki-67和E—cad在皮肤鳞状细胞癌和基底细胞癌的表达及相关分析

目的观察NF．KB、Ki-67和E—cad在皮肤基底细胞癌（BCC）和鳞状细胞癌（SCC）的表达,并探讨其意义。方法采用免疫组化EnVision二步法检测30例皮肤BCC和50例皮肤SCC（其中Ⅰ级26例,Ⅱ～Ⅲ级24例）中的NF—KB、Ki-67和E—cad表达,并以20份正常皮肤组织作为对照组。结果NF—KB、Ki-67在皮肤BCC和SCC的阳性表达率显著高于对照组,且在皮肤SCC的阳性表达率显著高于BCC（P〈0．05）。SCCⅡ-Ⅲ级强阳性率（＋＋-＋＋＋）显著高于SCCI级（P〈0．05）。E—cad在正常皮肤中呈阳性表达,但在肿瘤组织中的表达下降,尤以SCC下降明显,其中在SCCⅡ～Ⅲ级中的表达较SCCI级下降明显（P〈0．05）。皮肤BCC和SCC组织中NF—KB和Ki-67的阳性细胞表达呈正相关（P〈0．05）,NF．KB和E—cad的表达呈负相关（P〈0．05）。结论随着肿瘤细胞分化程度的降低,NF．KB、Ki-67的表达有增高趋势,E．cad的表达有下降趋势。提示BCC和SCC侵袭性生长与NF—KB、Ki-67的表达增高有关,SCC易发生转移的特性与E—cad的低表达有关。NF—KB信号转导通路有可能通过对凋亡基因的控制来对Ki-67、E—cad进行调节,进而控制肿瘤。     

非小细胞肺癌中PI3K/Akt信号通路通过Cdh1调控Skp2表达的机制研究

目的探讨非小细胞肺癌（NSCLC）中Cdc20同源蛋白1（Cdh1）参与磷脂酰肌醇三羟基激酶（PI3K）/Akt信号通路对S期激酶相关蛋白2（Skp2）表达调控的机制。方法体外培养NSCLC细胞系A549、LK2和H460,LY294002特异性阻断PI3K/Akt信号通路后,Western blot检测Skp2、Cdh1及p-Akt蛋白表达的变化,免疫荧光（IF）检测Cdh1在NSCLC中的定位变化。结果 LY294002处理后,与对照组相比3种细胞中Skp2蛋白表达和Akt磷酸化水平均降低（P〈0.01）,Cdh1在3种细胞的核内表达均增多。结论 NSCLC中PI3K/Akt信号通路抑制剂LY294002使Skp2蛋白表达下调与Cdh1由细胞质向细胞核转位有关。     

人Cdc25C基因克隆及其原核表达载体的构建与表达

目的:构建人Cdc25C基因的克隆载体和原核表达载体,并诱导其在大肠杆菌中表达.方法:从人肝癌细胞株Bel-7404中提取总R N A,经RT-P C R法扩增人C d c25C c D N A后,将其正确插入克隆载体pMD18-T和表达载体pET-32a(+),并转化至BL21(DE3)、BL21(DE3)pLysS和Transetta(DE3)三种感受态大肠杆菌中,分别采用0.25 mmol/L IPTG和ArtMediaTM Protein Expression自动诱导表达培养基诱导表达,并对纯化的融合蛋白进行考马斯亮蓝染色和质谱分析鉴定.结果:成功扩增了Cdc25C基因,并获得p M D18-T-C d c25C克隆载体和p E T-32a(+)Cdc25C表达载体;重组质粒在BL21(DE3)、BL21(DE3)pLysS和Transetta(DE3)三种感受态大肠杆菌中均诱导表达出TRx-His-Cdc25C融合蛋白;考马斯亮蓝染色和蛋白质谱分析结果显示基因重组蛋白与目的蛋白相符.结论:获得肿瘤相关抗原Cdc25C重组蛋白,为后续研究奠定基础.     

灵芝酸对锂-匹鲁卡品致痫大鼠海马神经元的保护作用

目的观察灵芝酸对氯化锂-匹鲁卡品致痫大鼠海马神经元p-Akt、Akt蛋白表达的影响,并通过应用wortmannin阻断PI3K/Akt通路,探讨灵芝酸是否具有抗癫痫作用及其作用机制。方法选取雄性SD大鼠50只,随机分为5组(n=10),A组:生理盐水对照组,B组:癫痫模型组,C组:灵芝酸干预组,D组:wortmannin抑制剂组,E组:二甲基亚砜(DMSO)对照组。每组给予相应药后,对大鼠进行行为学观察、HE染色法检测海马神经元细胞形态学变化,免疫组化法检测各组大鼠海马区p-Akt、Akt蛋白表达。结果与A组相比,B、C、D、E组p-Akt、Akt的表达量相对较高(P0.01);灵芝酸干预后,C、D、E组p-Akt、Akt的表达量明显比B组增高(P0.05);PI3K/Akt通路被阻断后,C、E两组p-Akt、Akt的表达量明显比D组增高(P0.05)。结论灵芝酸对海马神经元具有一定的保护作用,并且其机制与PI3K/Akt通路的活化并影响其下游蛋白的表达有关。     

PPN／MG61、CyclinB2在甲状腺肿瘤组织及外周血中的表达

利用Realtime RT—PCR技术检测PPN／MG61、CyclinB2在甲状腺肿瘤患者肿瘤组织及外周血的表达情况，分析上述指标的相互关系。发现CyclinB2的表达在甲状腺乳头状癌组织和外周血血清中明显高于甲状腺良性疾病（P〈0．05）；PPN／MG61基因的表达呈反向变化趋势。提示PPN／MG61、CyclinB2有可能作为甲状腺肿瘤术前良恶性诊断的指标。     

脂联素对脓毒症大鼠急性肺损伤、肺毛细血管通透性的影响及机制

目的观察脂联素（APN）对脓毒症大鼠急性肺损伤（ALI）及肺毛细血管通透性的影响,并分析可能机制。方法将120只雄性sD大鼠按随机数字表法分为模型组、APN干预组、APN治疗组及对照组各30只,前三组均以盲肠结扎穿孔法构建脓毒症动物模型,对照组大鼠开腹后仅分离盲肠,不结扎穿孔;其中APN干预组、治疗组分别于制模前后腹腔注射基因重组APN。每组随机抽取大鼠20只于术后24h处死,取肺组织光镜下观察损伤程度,并进行评分;RT—PCR法检测肺组织T0u样受体4（TLR4）mRNA、NF—KBmRNA表达;ELISA法检测肺组织血管内皮生长因子（VEGF）、细胞间黏附分子（ICAM）-1及血管细胞黏附分子（VCAM）-1水平;Westernblotting法检测肺组织总Akt（t-Akt）、磷酸化Akt（p-Akt）含量;每组剩余10只大鼠采用伊文思蓝法检测肺毛细血管通透性。结果与对照组比较,余三组肺组织损伤明显,肺损伤评分、TLR4mRNA、NF—KBmRNA表达及VEGF、ICAM-1、VCAM-1水平均显著升高,肺毛细血管通透性、肺组织p-Akt含量均显著增加,但APN干预组、治疗组上述前七项指标均显著低于模型组,仅肺组织p-Akt含量显著高于模型组（P均〈0．05）;模型组肺组织NF—KBmRNA表达与TLR4mRNA、VEGF、ICAM-1及VCAM．1水平均呈显著正相关（P均〈0．05）。结论APN可明显减轻脓毒症大鼠ALI、降低肺毛细血管通透性,机制可能为通过磷脂酰肌醇3-激酶/Akt／Akt信号传导通路抑制NF—KB活化,降低VEGF、ICAM-1及VCAM．1表达。     

脂脉宁对香烟提取物诱导血管内皮细胞-304的NF-KB及热休克蛋白-70表达影响

目的：观察含脂脉宁血清对香烟提取物（CSE）诱导血管内皮细胞（VEC）～304的核转录因子-xB（NF—xB）及热休克蛋白-70（HSP-70）表达的影响。方法：将VEc-304细胞分为4组：CSE组、实验1组（脂脉宁大剂量）、实验2组（脂脉宁小剂量）及空白对照组。采用免疫组化方法,观察各组VEC-304细胞NF—KB及HSP-70的表达。结果：CSE组细胞NF—KB[（288±25）：（185±14）]、HsP-70[（370±28）：（258±20）]的表达均较空白对照组明显升高[P〈O．05～O．01],而脂脉宁两组NF—KB[1组（193±17）,2组（211±14）]、HSP-70[1组（262±21）,2组（282±23）]表达明显低于CSE组[P〈O．05～0．01],且1组作用更明显（P〈0．05）。细胞DAB显色：CSE组细胞NF—xB蛋白、HsP-70蛋白显色呈棕黄或棕褐色,明显较空白对照组色深;实验1组和2组显色虽较空白对照组为深,但明显较CSE组色浅。结论：香烟提取物可诱导血管内皮细胞核转录因子-kB、热休克蛋白～70表达．脂脉宁则可使其表达下调。     

PTEN/MMAC1/TEP1 suppresses the tumorigenicity and induces G1 cell cycle arrest in human glioblastoma cells

PTEN/MMAC1/TEP1 is a tumor suppressor that possesses intrinsic phosphatase activity. Deletions or mutations of its encoding gene are associated with a variety of human cancers. However, very little is known about the molecular mechanisms by which this important tumor suppressor regulates cell growth. Here, we show that PTEN expression potently suppressed the growth and tumorigenicity of human glioblastoma U87MG cells. The growth suppression activity of PTEN was mediated by its ability to block cell cycle progression in the G₁ phase. Such an arrest correlated with a significant increase of the cell cycle kinase inhibitor p27^KIP1 and a concomitant decrease in the activities of the G₁ cyclin-dependent kinases. PTEN expression also led to the inhibition of Akt/protein kinase B, a serine-threonine kinase activated by the phosphatidylinositol 3-kinase (PI 3-kinase) signaling pathway. In addition, the effect of PTEN on p27^KIP1 and the cell cycle can be mimicked by treatment of U87MG cells with LY294002, a selective inhibitor of PI 3-kinase. Taken together, our studies suggest that the PTEN tumor suppressor modulates G₁ cell cycle progression through negatively regulating the PI 3-kinase/Akt signaling pathway, and one critical target of this signaling process is the cyclin-dependent kinase inhibitor p27^KIP1.     

Diazepam enhances hypericin-induced photocytotoxicity and apoptosis in human glioblastoma cells

Glioblastoma multiforme (GBM) is neoplasm which is resistant to all currently used treatment modalities including surgery, radiation therapy and chemotherapy. Photodynamic therapy (PDT) has been suggested as a novel therapeutical approach to the treatment of malignant gliomas. Here, we attempted to enhance hypericin-induced photocytotoxicity and apoptosis by diazepam, a non-selective ligand of peripheral benzodiazepine receptors (PBR) which seem to play an important role in apoptosis regulation. For the study, we used U-87 MG and U373 MG glioma cell lines and primary cultures of GBM cells prepared from peroperatively obtained tumor specimens. The patients included 7 histologically confirmed GBMs. Colorimetric MTT assay was employed to study the photocytotoxic effects of hypericin and diazepam. Flow cytometry was used to detect apoptosis and assess the proapoptotic effects of diazepam. We found that hypericin upon photoactivation exerts strong cytotoxic effects against U-87 MG and U373 MG cells as well as primary GBM cell cultures. No cytotoxic effect of hypericin was observed under dark conditions. Diazepam inhibited cell growth in U-87 MG cells and primary cultures whereas proliferation of U373 MG cells remained unaffected. When hypericin was combined with diazepam, photocytotoxicity was increased in U-87 MG cells and primary cultures unlike U373 MG cells. Flow cytometric analysis revealed photoactivated hypericin-induced apoptosis in both cell lines. Apoptosis was significantly enhanced by diazepam in U-87 MG cells. However, no such effect was observed in U373 MG cells. In the present study, we showed that photocytotoxic effect of hypericin in glioma cells can be potentiated by diazepam. This effect is underlied by the ability of diazepam to facilitate hypericin-induced apoptosis. This work provides support to performe clinical studies involving diazepam in the antiglioma treatment regimens as an apoptosis-modulating agent.     

Quercetin-induced growth inhibition and cell death in prostatic carcinoma cells (PC-3) are associated with increase in p21 and hypophosphorylated retinoblastoma proteins expression

Prostate cancer is the major health problem and the leading cause of male cancer death. Quercetin is a novel antitumor and antioxidant, whose molecular mechanism involved in cell cycle arrest in androgen independent prostate cancer cells remains unclear. In this study, we investigated the effects of quercetin on proliferation and cell cycle arrest by modulation of Cdc2/Cdk-1 protein in prostate cancer cells (PC-3). PC- 3 cells are human androgen independent cancer cells and were cultured with quercetin at concentrations of 50 and 100 μM for 24 h. Cell proliferation, apoptosis and cell cycle distribution were analyzed. Expression of Cdc2/Cdk-1, cyclin B1, cyclin A, p21/Cip1, pRb, pRb2/p130, Bcl-2, Bcl-X_L, Bax and caspase-3 proteins were studied with western blot analysis. Addition of quercetin led to substantial decrease in the expression of Cdc2/Cdk-1, cyclin B1 and phosphorlyated pRb and increase in p21. Flowcytometric analysis showed that quercetin blocks G2-M transition, with significant induction of apoptosis. Apoptosis markers like Bcl-2 and Bcl-X_L were significantly decreased and Bax and caspase-3 were increased. From this study, it was concluded that quercetin inhibits prostate cancer cell proliferation by altering the expression of cell cycle regulators and apoptotic proteins. This work was supported by grants from University Grants Commission (UGC award No. F.3.41 / 2002 (SR-II) dated 14-03-2002) to Dr. J. Arunakaran.     

粉防己碱对大鼠静止期肝星状细胞细胞周期的影响

目的观察粉防己碱对大鼠静止期肝星状细胞（HSCs）细胞周期的影响及机制。方法分离正常大鼠HSCs,培养48 h后给予粉防己碱（1.6μmol/L）和（或）TGF-β1（5μg/L）处理3 d。流式细胞仪检测细胞周期分布;应用RT-PCR法检测Cyclin D1、Cyc-lin E、p21WAF1/CiP1和p27Kip1表达;使用Western blot法检测Cyclin D1和PPARγ蛋白水平。结果粉防己碱使G0/G1期和G2/M期细胞增多,S期细胞数显著减少,抑制TGF-β1介导的G0/G1期细胞含量下调和S期细胞含量升高,上调p21WAF1/CiP1mRNA表达,抑制Cyclin D1而维持PPARγ蛋白在一定水平。结论在静止期HSC中,粉防己碱通过抑制Cyclin D1、上调p21WAF1/CiP1和维持PPARγ表达使HSCs出现G0/G1期停滞和S期向G2/M期转换加速。     

p38 mitogen-activated protein kinase contributes to cell cycle regulation by cAMP in FRTL-5 thyroid cells

OBJECTIVE: Thyrotropin activates the cAMP pathway in thyroid cells, and stimulates cell cycle progression in cooperation with insulin or insulin-like growth factor-I. Because p38 mitogen-activated protein kinases (p38 MAPKs) were stimulated by cAMP in the FRTL-5 rat thyroid cell line, we investigated (i) the effect of the specific inhibition of p38 MAPKs on FRTL-5 cell proliferation and (ii) the mechanism of action of p38 MAPKs on cell cycle control, by studying the expression and/or the activity of several cell cycle regulatory proteins in FRTL-5 cells. METHODS: DNA synthesis was monitored by incorporation of [(3)H]thymidine into DNA and the cell cycle distribution was assessed by fluorescence-activated cell sorter analysis. Expression of cell cycle regulatory proteins was determined by Western blot analysis. Cyclin-dependent kinase 2 (Cdk2) activity associated to cyclin E was immunoprecipitated and was measured by an in vitro kinase assay. RESULTS: SB203580, an inhibitor of alpha and beta isoforms of p38 MAPKs, but not its inactive analog SB202474, inhibited DNA synthesis and the G1-S transition induced by forskolin plus insulin. SB203580 inhibited specifically p38 MAPK activity but not other kinase activities such as Akt and p70-S6 kinase. Treatment of FRTL-5 cells with SB203580 decreased total and cyclin E-associated Cdk2 kinase activity stimulated with forskolin and insulin. However, inhibition of p38 MAPKs by SB203580 was without effect on total cyclin E and Cdk2 levels. The decrease in Cdk2 kinase activity caused by SB203580 treatment was not due to an increased expression of p21(Cip1) or p27(Kip1) inhibitory proteins. In addition, SB203580 affected neither Cdc25A phosphatase expression nor Cdk2 Tyr-15 phosphorylation. Inhibition of p38 MAPKs decreased Cdk2-cyclin E activation by regulating the subcellular localization of Cdk2 and its phosphorylation on Thr-160. CONCLUSIONS: These results indicate that p38 MAPK activity is involved in the regulation of cell cycle progression in FRTL-5 thyroid cells, at least in part by increasing nuclear Cdk2 activity.     

连翘三萜类化合物对前列腺癌PC-3细胞增殖抑制及放疗敏感性的实验研究

目的探讨连翘三萜类化合物达玛-24-烯-3β-乙酰氧基-20s-醇（DM）对人前列腺癌PC-3细胞的增殖抑制及放疗增敏作用。方法采用流式细胞术检测不同浓度DM液对PC-3细胞周期、凋亡的影响;PC-3细胞接受6-mVX线照射,用克隆形成法检测细胞存活分数、计算放疗增敏比;端粒重复序列扩增法检测DM对PC-3细胞端粒酶活性的抑制作用;实时定量PCR测定DM对PC-3细胞周期相关基因表达的影响。结果 DM可诱导PC-3细胞凋亡,其作用6 h后肿瘤细胞端粒酶活性降低,48 h后渐恢复至正常。DM可使细胞周期相关基因p21、TGF-β、Smad3表达增加,Cyclin D1、CDC25A表达降低（P均〈0.05）。DM有放疗增敏作用,其放疗增敏比为1.80。结论 DM可诱导PC-3细胞凋亡,抑制其细胞端粒酶活性,调节细胞周期相关基因表达,对前列腺癌PC-3细胞有放疗增敏作用。     

Interferon-alpha delays S-phase progression in human hepatocellular carcinoma cells via inhibition of specific cyclin-dependent kinases

The potential antiproliferative effects of interferon-alpha (IFN-alpha) in the treatment of hepatocellular carcinoma (HCC) are controversial, and the growth inhibitory mechanisms remain poorly understood. Therefore, the current study was designed to delineate the molecular mechanisms responsible for direct antiproliferative actions of IFN-alpha in HCC cells. IFN-alpha receptor expression and signal transduction were examined by RT-PCR, immunoprecipitation, Western analysis, and transient transactivation assays. Effects of IFN-alpha on cell growth and cell-cycle distribution were evaluated based on cell numbers and flow cytometry. Composition and activity of cyclin-dependent kinase complexes were determined by immunoblotting and histone-H1-kinase assays. Expression of IFN-alpha receptors was found in all 3 HCC cell lines. IFN-alpha binding initiated phosphorylation of Jak1 and Tyk2 kinases leading to Stat1/Stat2 activation, nuclear translocation, and transactivation of an ISRE-luciferase reporter gene construct. IFN-alpha treatment resulted in a time- and dose-dependent reduction of proliferation. Cell cycle analysis of G1-synchronized, IFN-alpha-treated HCC cells revealed a substantial delay in S-phase progression but no alteration of G1/S-phase transition or evidence of apoptotic cell death. Reflecting the time course of S-phase accumulation, cell cycle-dependent induction of Cyclin A and Cyclin B was impaired, resulting in reduced activity of Cdk2 and Cdc2 kinases. Furthermore, Cdc25C was selectively down-regulated. IFN-alpha treatment inhibits growth of HCC cells by specifically delaying S-phase progression, most likely because of inhibition of Cyclin A induction, resulting in decreased activity of the associated Cdk2 and Cdc2 kinases.