HCV核心蛋白与NS4B对HepG2细胞增殖的影响

目的 探讨HCV核心蛋白与非结构蛋白4B（NS4B）对HepG2细胞增殖的影响及可能机制.方法 重组质粒pcDNA3.1（-）Core与pcDNA3.1（-）NS4B单独和联合转染HepG2细胞,同时以转染空载体和未转染HepG2细胞作为对照.RT-PCR及Western Blot检测各组细胞中HCVCore、NS4B 、Wnt1、β-catenin 、c-myc及CyclinD1表达;MTT法,平板克隆形成试验检测HCV核心蛋白与NS4B对HepG2细胞增殖的影响;流式细胞术检测细胞周期.结果 ①pcDNA3.1（-）Core与pcDNA3.1（-）NS4B单独和联合转染HepG2细胞,成功表达HCV Core或/（和）NS4B mRNA和蛋白.②pcDNA3.1（-）Core和pcDNA3.1（-）NS4B单独转染和联合转染的HepG2细胞Wnt1、β-catenin、c-myc、CyclinD1 mRNA与蛋白的相对表达量均高于HepG2/pcDNA3.1（-）组和HepG2组（P＜0.01）.③与HepG2/pcDNA3.1（-）组和HepG2组比较,pcDNA3.1（-）Core和pcDNA3.1（-） NS4B单独转染和联合转染的HepG2细胞活力和克隆形成能力增强,S期和G2/M期细胞比例升高（P＜0.01）.结论 HCV核心蛋白与NS4B能加速HepG2细胞周期进程,促进细胞增殖,这种效应可能与其增强Wnt1、β-catenin、c-myc及CyclinD1的表达相关.     

PRL-2基因转染对肝细胞增殖及细胞周期的影响

目的：研究PRL-2基因对肝细胞增殖和细胞周期的影响。方法:采用脂质体转染的方法将重组质粒稳定转染至正常永生化肝细胞系CL1中，G418筛选阳性克隆。应用实时荧光定量聚合酶链反应、Western印迹和免疫组化分析PRL-2在阳性细胞的表达及蛋白定位，MTT法检测细胞的群体倍增时间，流式细胞仪检测细胞周期变化，Western印迹分析细胞周期素A、D1、E以及周期蛋白依赖激酶抑制因子p16、p21WAF1及p27Kip1的变化,实时荧光定量聚合酶链反应检测p21WAF1mRNA的变化。结果: 成功构建PRL-2真核表达载体pcDNA3-PRL-2。脂质体转染细胞经过G418筛选后,获得稳定表达PRL-2的细胞亚系PRL-2-CL1。经实时荧光定量PCR、Western印迹和免疫组化证实,PRL-2-CL1细胞系PRL-2基因及蛋白表达水平高于对照组，流式细胞仪检测细胞周期S期细胞比例明显增高，MTT法检测细胞群体倍增时间缩短。Western印迹及实时荧光定量聚合酶链反应显示p21WAF1在转染后较对照组明显降低，细胞周期素A、D1、E及p16、p27Kip1无明显变化。结论: 重组PRL-2真核表达载体构建正确,并在永生化肝细胞中获得稳定、高效表达。PRL-2基因具有促进细胞增殖的作用，这种作用与其降低p21WAF1蛋白含量相关。     

Hepatitis C virus (HCV) NS2 protein up-regulates HCV IRES-dependent translation and down-regulates NS5B RdRp activity

Chronic hepatitis C virus (HCV) infection often leads to liver cancer. The HCV NS2 protein is a hydrophobic transmembrane protein that associates with several cellular proteins in mammalian cells. In this report, we investigated the function of NS2 protein on HCV replication and translation by using a transient cell-based expression system. Cells co-transfected with pcDNA3.1 (−)-NS2 and the dual-luciferase reporter construct containing the HCV IRES were used to detect the effect of NS2 protein on HCV translation. Cells co-transfected with pcDNA3.1(−)-NS2, pcDNA-NS5B and a reporter plasmid were used to detect the effect of NS2 protein on HCV replication. The results showed that HCV NS2 protein up-regulated HCV IRES-dependent translation in a specific and dose-dependent manner in Huh7 cells but not in HeLa and HepG2 cells, and NS2 protein inhibited NS5B RdRp activity in a dose-independent manner in all three cell lines. These findings may suggest a novel mechanism by which HCV modulates its NS5B replication and IRES-dependent translation and facilitates virus persistence. Y. She and Q. Liao contributed equally to this work.     

KLF4对结直肠癌细胞生长抑制及化疗敏感性的影响

目的:探讨Krüppel样因子4(KLF4)对结直肠癌细胞活力、凋亡及顺铂化疗敏感性的影响。方法:Western blot法检测KLF4在结直肠癌Caco2、SW480和HCT116细胞中的表达。将SW480细胞分为pc DNA3. 1组(转染pc DNA3. 1空质粒)、pc DNA3. 1-KLF4组(转染构建的pc DNA3. 1-KLF4过表达质粒)和pc DNA3. 1-KLF4+顺铂组(转染pc DNA3. 1-KLF4 48 h后用1 mg/L顺铂处理细胞48 h),Western blot检测KLF4、p-IκBα、细胞周期素D1(cyclin D1)和生存素(survivin)的蛋白水平; CCK-8法检测各组细胞活力;流式细胞术检测细胞凋亡率; DCFH-DA探针检测活性氧簇(ROS)含量。结果:KLF4在结直肠癌细胞中的表达均显著低于在人结肠黏膜上皮NCM460细胞的表达(P 0. 05)。与pc DNA3. 1组相比,pc DNA3. 1-KLF4组的KLF4蛋白表达显著增高(P 0. 05),细胞活力及cyclin D1和survivin的蛋白表达均显著降低,细胞凋亡率、ROS含量及p-IκBα的蛋白表达均显著增高;而pc DNA3. 1-KLF4+顺铂组细胞活力及cyclin D1和survivin的蛋白表达均显著低于pc DNA3. 1-KLF4组,细胞凋亡率、ROS含量及p-IκBα的蛋白表达均显著高于pc DNA3. 1-KLF4组(P 0. 05)。结论:上调结直肠癌细胞KLF4基因表达可降低肿瘤细胞活力,诱导细胞凋亡,增强顺铂化疗敏感性,其机制可能与提高细胞内ROS含量及下调NF-κB信号关键分子IκBα的磷酸化水平有关。     

阿片类生长因子受体抑制雄激素依赖性前列腺癌LNCaP细胞的生长

目的:观察阿片类生长因子受体(opioid growth factor receptor,OGFr)对雄激素依赖性前列腺癌LNCaP细胞活力的影响.方法:将LNCaP细胞随机分为非转染组、空白质粒组(转染pcDNA3.1空白质粒)和OGFr质粒组(转染表达质粒pcDNA3.1-OGFr),RT-qPCR和Western...     

线粒体铁蛋白过表达抑制神经肿瘤细胞的增长与细胞铁代谢及细胞周期蛋白表达相关

目的 探讨过表达线粒体铁蛋白（MtFt） 抑制成神经母细胞瘤SH-SY5Y细胞的增殖机制。方法 以过表达MtFt的成神经母细胞瘤细胞MtFt-SY5Y为实验模型,野生型SH-SY5Y和pcDNA3.1-SY5Y（空质粒对照）为实验对照,运用流式细胞术、Western blotting技术等检测了MtFt对SH-SY5Y肿瘤细胞增殖的影响及铁代谢相关蛋白转铁蛋白受体1 （TfR1）,铁蛋白和细胞周期相关蛋白（cyclin）及其依赖性激酶（CDK）、cyclinD1、CDK4、cyclinE、CDK2的表达变化。结果 MtFt过表达通过调节细胞内铁代谢显著抑制了神经肿瘤细胞SH-SY5Y的增殖,与对照组相比,MtFt-SY5Y细胞增殖速度慢了近4倍。MtFt造成了细胞质内铁缺乏, TfR1表达显著上调,而铁蛋白H 亚基（H-ferritin）显著下调。同时 cyclinD1与CDK2蛋白表达显著降低,cyclinE蛋白表达显著上升,CDK4蛋白表达无显著性差异。结论 MtFt过表达能够显著抑制神经肿瘤细胞的生长,其机制可能是通过调节细胞内铁代谢,从而影响细胞周期相关蛋白及其周期蛋白激酶的表达。     

人表皮生长因子受体显性负性突变体诱导胃癌细胞发生G0/G1期阻滞

 目的：探讨人表皮生长因子受体显性负性突变体（dominant negative epidermal growth factor receptor,DNEGFR）对胃癌细胞细胞周期的影响及其分子机制。方法：选用2株人胃癌细胞,分为如下6组：SGC-7901细胞未转染组（US组）、SGC-7901细胞pEGFP-N1质粒转染组(ES组)、SGC-7901细胞pEGFPN1-DNEGFR质粒转染组(DS组)、NCI-N87细胞未转染组（UN组)、NCI-N87细胞pEGFP-N1质粒转染组(EN组)和NCI-N87细胞pEGFPN1-DNEGFR质粒转染组(DN组)。采用流式细胞术检测细胞周期,Western blotting检测细胞周期素依赖性蛋白激酶2（CDK2）、cyclin D1、Ser9位点磷酸化糖原合成酶激酶3β［p-GSK-3β(Ser9)］、p21和p27蛋白水平。结果：转染pEGFPN1-DNEGFR质粒的人胃癌细胞株出现G0/G1期阻滞,CDK2、cyclin D1和p-GSK-3β（Ser9）蛋白水平降低,p21和p27蛋白水平则升高。结论：DNEGFR通过激活GSK-3β使cyclin D1蛋白水平降低,并降低CDK2蛋白水平,上调p21和p27蛋白水平,最终导致胃癌细胞发生G0/G1期阻滞。这一结果将为胃癌生物治疗研究提供新思路。     

HIV-1 Vpr对细胞周期的影响和致凋亡作用的研究

目的 研究人免疫缺陷病毒1型(HIV-1)的vpr基因和不同变异株对宿主细胞周期和凋亡的影响,以及其致细胞周期变化和致细胞凋亡机制的两者间的可能关系.方法 将14个带有不同变异位点的中国感染者HIV-1 upr片段分别连入pcDNA3.1(+)真核表达载体,构建重组质粒.将这些重组质粒电转染Jurkat细胞,并设立保守株vpr基因转染细胞、突变株vpr-Fs基因转染细胞、空载体转染细胞和未转染细胞作为对照.经G418选择培养及RT-PCR检测目的基因转染成功后,PI染色,流式细胞仪检测被转染细胞的细胞周期分布和细胞凋亡.结果 流式细胞仪检测上述14个带有不同变异位点的HIV-1 vpr基因片段的Jurkat细胞,发现转染保守片段HIV-1 vpr的Jurkat细胞,其细胞周期出现G_2期阻滞和细胞凋亡率明显升高,但转染vpr C端截断的vpr-Fs片段的细胞、空载体peDNA3.1(+)转染细胞和未转染的Jurkat细胞无此现象.转染了,HIV-1 vpr基因序列相对应的Vpr蛋白中含有70V、85P、86G、94G突变的片段,较vpr保守片段其致感染细胞G_2期阻滞和凋亡的能力明显下降,且Vpr蛋白的AE亚型致细胞周期阻滞和致凋亡能力较其他亚型普遍为低.初步发现vpr诱导G2期阻滞百分比越高其所致凋亡率越高.结论 HIV-I vpr基因有明显的致感染细胞G_2周期阻滞和致细胞凋亡的作用,但vpr C端截断的vpr-Fs片段无此功能.首次发现中国感染者HIV-1 vpr基因表达蛋白的70V、85P、86G、94G位点突变能使其致感染细胞G_2期阻滞和凋亡的能力下降,Vpr的AE亚型致细胞周期阻滞和凋亡能力较其他亚型普遍为低.对14个变异片段的分析显示vpr诱导G_2期阻滞的程度与其致凋亡水平可能相关,提示两者的发生机制可能有一定的关联.本研究为进一步探讨HIV-1致病机制和探索可能的基因干预措施打下基础.     

Simvastatin inhibits cell growth and induces apoptosis and G0/G1 cell cycle arrest in hepatic cancer cells

Hepatocellular carcinoma (HCC) is one of major health concerns worldwide and one of leading causes of cancer death after lung and gastric cancers. Simvastatin is a cholesterol-lowering drug which inhibits 3-hydroxy-3-methylglutarylcoenzyme CoA (HMG-CoA) reductase. Simvastatin exhibits numerous pleiotropic effects including anti-cancer activity. Yet, the anticancer effects in HCC remain poorly characterized. Therefore, in this study, we investigated the effects of simvastatin on tumor cell growth, apoptosis and cell cycle. HepG2 and Huh7 cell lines were treated with simvastatin (32 and 64 μM) for different time periods. Tumor cell growth was assessed using MTT assay. Apoptosis and cell cycle analysis were also evaluated. Analysis of cell cycle proteins involved in simvastatin-induced manipulation was performed by Western blot and quantitative RT-PCR analyses. Simvastatin induced a reduction of tumor cell growth. In both cell lines, simvastatin induced apoptosis and impaired cell cycle progression as depicted by the greater rates of G0/G1-phase cells than the rates of S-phase cells. Protein expression levels of cell cycle regulating proteins CDK1, CDK2, CDK4, cyclin D1, cyclin E, p19 and p27 were markedly altered by simvastatin. Moreover, CDC2, CCND1 and CDCN2D mRNA expressions were also altered by drug treatment. Collectively, these results suggest that simvastatin induces apoptosis in tumor cells and its anti-proliferative activity was accompanied by inhibition of cyclin-dependent kinases and cyclins, whereas CDK inhibitors p19 and p27 were enhanced. These results may provide novel insights into simvastatin tumor-suppressive action.     

AEG-1表达下调对人宫颈癌细胞细胞周期和侵袭能力的影响及其机制

 目的：研究星形细胞上调基因1（astrocyte elevated gene-1,AEG-1）在人宫颈鳞癌细胞和组织中的表达,探讨AEG-1表达下调对宫颈癌SiHa细胞细胞周期和侵袭能力的影响,并分析其可能的分子机制。方法：采用Western blotting检测正常宫颈组织、宫颈鳞癌组织、HeLa、SiHa和CaSki细胞中AEG-1蛋白的表达。将对照siRNA和AEG-1 siRNA分别转染SiHa细胞,利用Western blotting检测SiHa细胞中AEG-1蛋白的表达,采用流式细胞术检测细胞周期分布的变化,采用Boyden小室检测细胞侵袭能力的变化,最后采用Western blotting检测cyclin D1、细胞周期素依赖性激酶 2（CDK2）和基质金属蛋白酶9(MMP-9)蛋白表达的变化。结果：宫颈鳞癌组织中AEG-1蛋白表达显著高于正常宫颈组织（P<0.05）,同时3株宫颈癌细胞中AEG-1蛋白表达均显著高于正常宫颈组织,其中SiHa细胞中AEG-1蛋白表达最高（P<0.05）。此外,AEG-1 siRNA能显著下调SiHa细胞中AEG-1蛋白的表达（P<0.05）,其表达下调能明显促使SiHa细胞在G0/G1期的比例增加和降低其侵袭能力。Western blotting结果表明,AEG-1 siRNA组中cyclin D1、CDK2和MMP-9蛋白的表达均显著低于未处理组和对照siRNA组（P<0.05）。结论：AEG-1在宫颈癌中的高表达可能与宫颈癌的发生发展密切相关,其表达下调介导的细胞周期静止和侵袭能力降低可能与cyclin D1、CDK2和MMP-9蛋白表达下调密切相关。     

丙型肝炎病毒非结构蛋白NS4A反式激活基因的克隆化研究

目的应用抑制性消减杂交（SSH）技术构建丙型肝炎病毒非结构蛋白4A（HCV NS4A）转染细胞差异表达cDNA消减文库，克隆HCV NS4A蛋白反式激活相关基因。方法以HCV NS4A表达质粒pcDNA3．1（-）-NS4A转染Hep G2细胞，以空载体pcDNA3．1（-）为对照，制备转染后的细胞裂解液，提取mRNA并逆转录为cDNA，进行SSH分析。将富集的二次PCR产物与TIA载体连接，并转染大肠埃希菌进行文库扩增，随机挑取克隆，聚合酶链反应（PCR）扩增后进行测序及同源性分析。结果文库扩增后得到36个阳性克隆，经菌落PCR分析显示200～1000bp插入片段。对其中的25个片段测序，并进行同源性分析，显示18种已知基因编码蛋白和2种未知功能基因序列，包括一些与细胞周期、细胞凋亡、信号传导及肿瘤发生等细胞生长调节密切相关的蛋白编码基因，可能是NS4A反式激活靶基因。结论成功构建了HCV NS4A反式激活基因差异表达的cDNA消减文库，为进一步阐明HCV NS4A反式调节的靶基因等提供了相关的平台。     

Survivin-2B诱导人乳腺癌细胞凋亡的初步研究*

 目的：探讨存活蛋白2B (survivin-2B)在诱导肿瘤细胞凋亡中的分子机制。方法：将survivin-2B基因插入真核表达载体pCDNA3.1,得到重组载体pCDNA3.1-survivin-2B。将空载体pCDNA3.1及重组载体pCDNA3.1-survivin-2B分别转染人乳腺癌细胞株MCF7,转染后48 h,用annexin V/7-AAD染色法分析细胞凋亡情况,利用碘化丙啶染色法分析转染对细胞周期的影响;同时提取总RNA并反转录成cDNA,进行多重聚合酶链反应。利用GeXP多基因表达分析系统检测21个与肿瘤相关基因的表达情况。结果：过表达survivin-2B基因导致MCF7细胞凋亡与细胞周期阻滞,并引起8个基因表达上调,2个基因表达下调。变化最大的为醛脱氢酶4家族成员A1（ALDH4A1）,表达下降48%;变化最小的为胞质分裂调控蛋白1（PRC1）,上调1.08倍。结论：Survivin-2B能够诱导细胞凋亡与细胞周期G2/M期阻滞,并引起部分肿瘤相关基因的表达变化。     

Polo-like激酶1反义RNA对肺癌细胞A549生长的实验研究

目的:探讨Polo-like激酶1(Plk1)基因表达下调对肺癌细胞周期分布及其生长的影响。方法:培养肺腺癌细胞株A549,构建表达Plk1反义RNA的质粒pcDNA3-Plk1,通过脂质体介导转染A549细胞,采用RT-PCR和Western blotting的方法检测Plk1基因的表达,细胞计数、BrdU脉冲标记检测细胞增殖,流式细胞仪分析细胞周期变化和凋亡,MTT法检测长春瑞宾(NVB)对各组细胞的生长抑制率。结果:A549细胞转染pcDNA3-Plk1后24h,Plk1mRNA及蛋白表达均下降;细胞变圆、漂浮、增殖减慢;S期细胞百分数(BrdU标记指数)显著低于对照组(P<0.05);转染后48hA549细胞出现G2/M期阻滞(P<0.05)并发生凋亡;等浓度化疗药物诺维本对转染pcDNA3-Plk1细胞的抑制率明显高于各对照组(P<0.05),转染pcDNA3与未转染的对照细胞差异无显著(P>0.05)。结论:pcDNA3-Plk1的转染能下调Plk1基因的表达,抑制A549细胞增殖,诱导凋亡,并能增加A549细胞对化疗药物的敏感性。     

MicroRNA-25 regulates small cell lung cancer cell development and cell cycle through cyclin E2

Purpose: We intended to examine the underlying mechanism of microRNA-25 (miR-25) in regulating small cell lung cancer (SCLC). Methods: The miR-25 expression was measured by quantitative RT-PCR (qRT-PCR) in 5 SCLC cell lines and 9 human SCLC tissues. In SCLC cell line H510A cells, endogenous miR-25 was downregulated by stable transfection of antisense oligonucleotide of miR-25 (miR-25-as). Then the effects of miR-25 downregulation on SCLC growth, invasion and chemoresistance were assessed by MTT, migration and cisplatin assays, respectively. Furthermore, the effects of miR-25 downregulation on cancer cell cycle arrest, production of cell cycle proteins cyclin E2 and CDK2 were examined by cell cycle assay, western blot and luciferase assays, respectively. Finally, cyclin E2 was over-expressed in H510A cells to investigate its effect on miR-25 mediated SCLC regulation. Results: In both SCLC cells and human SCLC tumor tissues, miR-25 was overexpressed. Down-regulation of miR-25 in H510A cells significantly reduced cancer cell growth, invasive capability and resistance to cisplatin. Also, it induced G1 cell cycle arrest and downregulated cell cycle related proteins cyclin E2 and CDK2. Luciferase assay demonstrated cyclin E2 was directly targeted by miR-25. Overexpression of cyclin E2 in H510A cells reversed the cell cycle arrest and restored invasive capability impaired by miR-25 downregulation. Conclusions: Our study shows miR-25 is overexpressed in SCLC and acting as oncogenic regulator by regulating cyclin E2.     

HCV core,NS3, NS5A and NS5B proteins modulate cell proliferation independently from p53 expression in hepatocarcinoma cell lines

Summary. Several reports have shown that activity and/or expression of p53 can be modulated by Hepatitis C virus (HCV) proteins and may interfere with normal regulation of cell growth. In order to understand the relationship between p53 function and HCV proteins expression, we have investigated potential effects of the core, NS3, NS5A and NS5B proteins on Huh-7 (p53 +/+) and Hep3B (p53 –/–) cell proliferation.The effect of HCV proteins transiently expressed after recombinant-adenoviral infection was analyzed by Western blot, crystal violet and propidium iodide staining.Expression of the core, NS3, NS5A or NS5B proteins inhibited cell proliferation and blocked both cell lines in the G2/M phase of the cell cycle. c-myc and p53 expression were respectively induced and increased in Huh-7 cells only following expression of the Core protein. No expression of p21^waf1/cip1 could be detected and expression of cyclin A, cdk2 and p27^Kip1 were independent of HCV proteins expression.Our results show that the effect of core, NS3, NS5A and NS5B on cell proliferation is independent of p53 expression and that only the Core protein, induces the expression of both c-myc and p53.     

丙型肝炎病毒核心蛋白对HepG2细胞生长周期的影响

目的: 构建丙型肝炎病毒核心蛋白(HCV-core-1b)真核重组质粒,获得稳定表达HCV-core-1b的HepG2细胞株,观察HCV-core-1b对HepG2细胞株生长周期及cyclin D1 和pRb/p130表达的影响,探讨丙型肝炎病毒慢性感染的可能机制。方法: 将HCV-core-1b亚克隆入pBabe-Flag-puro载体,获得重组质粒pBabe-Flag-HCV-core-1b;将重组质粒转染病毒包装细胞Pheonix 293T,筛选获得分泌HCV-core-1b的病毒包装细胞株。利用包装细胞产生的病毒上清感染靶细胞,筛选后获得稳定表达HCV-core-1b的HepG2细胞株,流式细胞仪检测靶细胞生长周期的变化,Western blotting检测cyclin D1 和pRb/p130蛋白的表达。结果: 基因测序确认HCV-core-1b亚型基因编码区完整无移位,与标签蛋白Flag形成融合蛋白。HepG2-HCV-core细胞株成功表达Flag-HCV-core-1b蛋白,并导致细胞cyclin D1 和 pRb/p130的水平下调,显著改变了HepG2细胞生长周期,使细胞阻滞在G₀/G₁期。结论: 成功构建了pBabe-Flag-HCV-core-1b真核表达质粒,获得稳定表达Flag-HCV-core-1b融合蛋白的HepG2细胞。由于HCV-core-1b蛋白的表达,下调了HepG2细胞 cyclin D1和pRb/p130的表达,显著抑制HepG2细胞生长周期。     

Polo-like激酶l反义RNA对肺癌细胞A549生长的实验研究

目的： 探讨Polo-like激酶1（Plk1）基因表达下调对肺癌细胞周期分布及其生长的影响。方法： 培养肺腺癌细胞株A549，构建表达Plk1反义RNA的质粒pcDNA3-Plk1，通过脂质体介导转染A549细胞，采用RT-PCR和Western blotting的方法检测Plk1基因的表达，细胞计数、BrdU脉冲标记检测细胞增殖，流式细胞仪分析细胞周期变化和凋亡，MTT法检测长春瑞宾（NVB）对各组细胞的生长抑制率。结果： A549细胞转染pcDNA3-Plk1后24 h，Plk1 mRNA及蛋白表达均下降；细胞变圆、漂浮、增殖减慢；S期细胞百分数（BrdU标记指数）显著低于对照组（P<0.05）；转染后48 h A549细胞出现G₂/M期阻滞（P<0.05）并发生凋亡；等浓度化疗药物诺维本对转染pcDNA3-Plk1细胞的抑制率明显高于各对照组（P<0.05），转染pcDNA3与未转染的对照细胞差异无显著（P>0.05）。结论： pcDNA3-Plk1的转染能下调Plk1基因的表达，抑制A549细胞增殖，诱导凋亡，并能增加A549细胞对化疗药物的敏感性。     

Herpes simplex virus type 1 infection imposes a G(1)/S block in asynchronously growing cells and prevents G(1) entry in quiescent cells

Herpes simplex virus type 1 (HSV-1) infection disrupted cell cycle regulation in at least two ways. First, infection of quiescent human embryonic lung cells simultaneously with readdition of serum caused inhibition of cyclin D/cyclin-dependent kinase (CDK) 4,6-specific and cyclin E/CDK2-specific phosphorylation of the retinoblastoma protein pRb. The inhibition of cyclin D/CDK4,6 kinase activity corresponded to a loss of cyclin D1 protein and a failure of CDK4 and CDK6 to translocate to the nucleus. Failure to detect cyclin E/CDK2 kinase activity was accompanied by a loss of cyclin E protein and a failure of CDK2 to translocate to the nucleus. Levels of pocket protein p130 persisted, whereas p107 did not accumulate. As a result of these effects on cyclin kinase, G(0)-infected cells failed to reenter the cell cycle. The second type of HSV-induced cell cycle dysregulation was observed in asynchronously dividing cell cultures. A rapid inhibition of preexisting cyclin E/CDK2 and cyclin A/CDK2 activities was observed in human embryonic lung cells, as well as two other human cell lines: C33 and U2OS. HSV-1 immediate-early gene expression was necessary for the inhibition of CDK2 kinase activity. Cyclin and CDK subunit protein levels, intracellular localization, and complex stability were unaffected by infection. In addition, levels of cyclin-dependent kinase inhibitors, p27 and p21, were not affected by HSV-1. Previous experiments demonstrated that in asynchronous infected cells, hypophosphorylated pRb and pocket protein-E2F complexes accumulated, and cellular DNA synthesis was rapidly inhibited. Coupled with the present results, this indicates that HSV-1 has evolved mechanisms for preventing cells in G(1) from proceeding through the restriction point and for cells in S from completing a round of DNA replication.     

高表达p27基因对子宫颈癌HeLa细胞增殖的影响

目的构建抑癌基因p27高表达细胞株,研究其对子宫颈癌HeLa细胞增殖的影响。方法运用RT-PCR技术从HeLaRNA中扩增p27 cDNA,连接酶连接至真核表达载体pcDNA3.1(+),所得的重组质粒pcDNA3.1(+)-p27用脂质体法转染子宫颈癌HeLa细胞,使用RT-PCR以及Western blot法筛选p27基因高表达的细胞株。MTT法和流式细胞术检测p27基因高表达对细胞增殖的影响。结果成功获得p27高表达的HeLa细胞株。细胞增殖分析和流式细胞术结果显示,p27基因高表达对细胞增殖有抑制作用,并明显增加G1期的细胞数(由44.4%增加到59%,P<0.05)。结论 p27基因在HeLa细胞中高表达能通过抑制细胞G1/S转换从而抑制细胞增殖,提示p27基因可能成为子宫颈癌基因治疗的靶基因。     

Transmissible gastroenteritis virus infection induces cell cycle arrest at S and G2/M phases via p53-dependent pathway

p53 signaling pathway plays an important role in the regulation of cell cycle. Our previous studies have demonstrated that TGEV infection induces the activation of p53 signaling pathway. In this study we investigated the effects of TGEV infection on the cell cycle of host cells and the roles of p53 activation in this process. The results showed that TGEV infection induced cell cycle arrest at S and G2/M phases in both asynchronous and synchronized PK-15 and ST cells, while UV-inactivated TGEV lost the ability of induction of cell cycle arrest. TGEV infection promoted p21 accumulation, down-regulated cell cycle-regulatory proteins cyclins B1, cdc2, cdk2 and PCNA. Further studies showed that inhibition of p53 signaling could attenuate the TGEV-induced S- and G2/M-phase arrest by reversing the expression of p21 and corresponding cyclin/cdk. In addition, TGEV infection of the cells synchronized in various stages of cell cycle showed that viral genomic RNA and subgenomic RNA, and virus titer were higher in the cells released from S-phase- or G2/M phase-synchronized cells than that in the cells released from the G0/G1 phase-synchronized or asynchronous cells after 18 h p.i. Taken together, our data suggested that TGEV infection induced S and G2/M phase arrest in host cells, which might provide a favorable condition for viral replication.