Overexpressed MicroRNA-182 Promotes Proliferation and Invasion in Prostate Cancer PC-3 Cells by Down-Regulating N-myc Downstream Regulated Gene 1 (NDRG1)

MicroRNAs, non-coding 20–22 nucleotide single-stranded RNAs, result in translational repression or degradation and gene silencing of their target genes, and significantly contribute to the regulation of gene expression. In the current study, we report that miR-182 expression was significantly upregulated in prostate cancer tissues and four cell lines, compared to benign prostatic hyperplasia tissues and normal prostatic epithelial (RWPE-1) cells. Ectopic overexpression of miR-182 significantly promotes the proliferation, increases the invasion, promotes the G1/S cell cycle transition and reduces early apotosis of PC-3 cells, while suppression of miR-182 decreased the proliferation and invasion, inhibits the G1/S cell cycle transition and increase early apotosis of PC-3 cells. Additionally, we demonstrated that miR-182 could downregulate expression of NDRG1 by directly targeting the NDRG1 3′-untranslated region. In conclusion, our results suggest that miR-182 plays an important role in the proliferation of human prostate cancer cells by directly suppressing the tumor supressor gene NDRG1. We uncovered a new epigenetic regulation of NDRG1.     

PRC2 during vertebrate organogenesis: a complex in transition

During organogenesis, tissues expand in size and eventually acquire consistent ratios of cells with dazzling diversity in morphology and function. During this process progenitor cells exit the cell cycle and execute differentiation programs through extensive genetic reprogramming that involves the silencing of proliferation genes and the activation of differentiation genes in a step-wise temporal manner. Recent years have witnessed expansion in our understanding of the epigenetic mechanisms that contribute to cellular differentiation and maturation during organ development, as this is a crucial step toward advancing regenerative therapy research for many intractable disorders. Among such epigenetic programs, the developmental roles of the polycomb repressive complex 2 (PRC2), a chromatin remodeling complex that mediates silencing of gene expression, have been under intensive examination. This review summarizes recent findings of how PRC2 functions to regulate the transition from proliferation to differentiation during organogenesis and discusses some aspects of the remaining questions associated with its regulation and mechanisms of action.     

Time-course network analysis reveals TNF-α can promote G1/S transition of cell cycle in vascular endothelial cells

MOTIVATION: Tumor necrosis factor-alpha (TNF-α), a major inflammatory cytokine, is closely related to several cardiovascular pathological processes. However, its effects on the cell cycle of vascular endothelial cells (VECs) have been the subject of some controversy. To investigate the molecular mechanism underlying this process, we constructed time-course protein-protein interaction (PPI) networks of TNF-α induced regulation of cell cycle in VECs using microarray datasets and genome-wide PPI datasets. Then, we analyzed the topological properties of the responsive PPI networks and calculated the node degree and node betweenness centralization of each gene in the networks. We found that p21, p27 and cyclinD1, key genes of the G1/S checkpoint, are in the center of responsive PPI networks and their roles in PPI networks are significantly altered with induction of TNF-α. According to the following biological experiments, we proved that TNF-α can promote G(1)/S transition of cell cycle in VECs and facilitate the cell cycle activation induced by vascular endothelial growth factor. CONTACT: shaoli@mail.tsinghua.edu.cn SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.     

小干扰RNA抑制LRP16基因表达限制了MCF-7乳腺癌细胞增殖

雌激素雌二醇上调人乳腺癌细胞MCF 7中LRP16基因表达 ,该基因过表达促进MCF 7细胞增殖 .为进一步探讨LRP16基因不同表达水平对MCF 7细胞增殖的影响以及对雌激素的反应性增殖能力 ,采用针对LRP16基因特异的小干扰RNA策略 ,通过逆转录病毒介导及抗性筛选构建了LRP16基因被稳定抑制的 2个MCF 7细胞系 ,针对绿色荧光蛋白的干扰序列作为阴性对照 .Northern印迹实验检测了LRP16基因在各个细胞株中mNRA的水平 ,与对照组细胞比较 ,针对LRP16基因不同位置的 2个小干扰RNA可分别将该基因抑制 90 %和 6 0 % .细胞增殖试验结果显示 ,MCF 7细胞中LRP16基因表达抑制率越高 ,细胞增殖速率减慢越显著 (P <0 0 5 ) ;软琼脂集落形成试验结果显示 ,抑制LRP16基因在MCF 7细胞中表达 ,限制了细胞锚定非依赖性生长 ;细胞周期分析结果表明 ,LRP16基因抑表达使MCF 7细胞G1 S周期转换受抑 ;Western印迹结果表明 ,LRP16基因表达抑制的细胞中细胞周期蛋白E及细胞周期蛋白D1蛋白水平显著下调 ,但未检测到P5 3及Rb蛋白表达水平的影响 .雌二醇刺激的增殖实验结果显示 ,抑制LRP16基因表达没有消除MCF 7细胞的反应性增殖特征 .上述结果表明 ,LRP16基因表达量与MCF 7细胞增殖能力密切相关 ,抑制其表达可有效限制MCF 7细胞的增殖能力 ,提     

批次和流加培养中国仓鼠卵巢工程细胞的细胞周期相关基因转录谱分析

以表达人重组尿激酶原中国仓鼠卵巢 (CHO) 工程细胞系11G-S为研究对象,运用基因芯片技术比较了CHO工程细胞在批次及流加培养不同生长阶段基因表达水平的差异,在此基础上采用Genmapp软件,同时结合已知的细胞周期信号通路图,着重分析了批次及流加培养CHO工程细胞的细胞周期调控基因转录谱差异。在基因芯片涉及的19 191个目标基因中,批次和流加培养不同生长阶段CHO工程细胞的下调表达的基因数量多于上调表达基因数目;两种培养模式下的基因差异表达有着明显的不同,尤其是在细胞生长的衰退期,流加培养CHO工程细胞中下调表达的基因数量明显多于批次培养。有关调控细胞周期关键基因的转录谱分析表明,CHO工程细胞主要是通过下调表达CDKs、Cyclin及CKI家族中的Cdk6、Cdk2、Cdc2a、Ccne1、Ccne2基因及上调表达Smad4基因,来达到调控细胞增殖及维持自身活力的目的。     

Beta-adrenergic receptors (betaAR) regulate cardiomyocyte proliferation during early postnatal life.

Cardiomyocyte development switches from hyperplasmic to hypertrophic growth between postnatal days 3 and 4 in rats. The mechanisms responsible for this transition have been controversial. beta-Adrenergic receptor (betaAR) activation of mitogenic responses in vitro has been reported. We hypothesized that tonic activation of the betaAR signaling regulates cell division in neonatal cardiomyocytes via effects on signaling kinases known to be important in cell cycle regulation. The purpose of the current study was to elucidate the roles of betaAR in rat cardiomyocyte growth in vivo. We demonstrated that betaAR blockade induced a significant reduction in cardiomyocyte proliferation as measured by the BrdU labeling index. Blockade of betaAR did not affect p38 or p44/42 MAPK activities. We further demonstrated that betaAR blockade induced a prompt deactivation of the p70 ribosomal protein S6 kinase (p70 S6K). To confirm these results, we measured p70 S6K activity directly. Basal activity of p70 S6K in neonatal cardiomyocytes was fourfold higher than that of insulin-treated adult rat liver. The activity of p70 S6K was reduced by 60% within 1 min after betaAR blockade. We conclude that the betaAR are involved in regulation of neonatal cardiomyocyte proliferation and that this mitogenic control may be mediated via the p70 S6K pathway.     

Cell cycle regulation of the c-Myc transcriptional activation domain.

The product of the c-myc gene (c-Myc) is a sequence-specific DNA-binding protein that has previously been demonstrated to be required for cell cycle progression. Here we report that the c-Myc DNA binding site confers cell cycle regulation to a reporter gene in Chinese hamster ovary cells. The observed transactivation was biphasic with a small increase in G1 and a marked increase during the S-to-G2/M transition of the cell cycle. This cell cycle regulation of transactivation potential is accounted for, in part, by regulatory phosphorylation of the c-Myc transactivation domain. Together, these data demonstrate that c-Myc may have an important role in the progression of cells through both the G1 and G2 phases of the cell cycle.     

Specific checkpoints regulate plant cell cycle progression in response to oxidative stress

The effects of oxidative stress on plant cell cycle progression were studied both in cell suspensions and in planta . Oxidative stress of variable severity was imposed by the addition of different concentrations of the methyl-quinone, menadione, into the growth media. In cell suspensions, flow cytometry analyses demonstrated that low concentrations (20–50 μM) of menadione impaired the G1/S transition, slowed DNA replication, and delayed the entry into mitosis. Furthermore, cells in G1 were more sensitive to menadione-mediated oxidative stress than cells in S phase. Cell cycle arrest was associated with an inhibition of the activity of cyclin-dependent kinases, cell cycle gene expression, and a concomitant activation of stress genes. Menadione-mediated oxidative stress was shown to have very similar effects on tobacco plants, suggesting that a general regulation mechanism takes place in plants. These results define an oxidative stress checkpoint pathway that modulates both the expression of the core cell cycle genes and oxidative defence genes. Redox sensing could be of key importance in controlling cell cycle progression in environmental stress conditions.     

Eps15同源结构域包含蛋白2通过调控Cyclin D1-CDK4-pRb信号轴影响食管鳞癌细胞的增殖

微丝结合蛋白是微丝细胞骨架的重要组成成分,它们通过促进微丝的聚合和解聚来影响微丝的动力学。大量研究已经表明,微丝和微丝结合蛋白参与细胞癌变的所有阶段。我们通过对食管癌蛋白质组数据挖掘结果显示,微丝结合蛋白Eps15同源结构域包含蛋白2(EHD2)在食管癌组织中低表达,且EHD2低表达的食管癌患者预后不良。以往的研究已经证明,EHD2参与调控糖代谢、自噬和肿瘤迁移。然而,EHD2在食管癌进展中的作用和机制仍不清楚。本研究旨在探究EHD2在食管鳞癌细胞中的影响及其作用机制。免疫荧光和细胞组分分离结果显示,EHD2 不仅定位于细胞膜和细胞质,还存在于细胞核中。使用克隆形成实验、EdU细胞增殖实验和细胞流式术检测EHD2对食管鳞癌细胞增殖能力的影响。结果显示,过表达EHD2 和EHD2-3×NLS(核定位信号)抑制食管鳞癌细胞增殖和细胞周期G₁/S转换;同时,双荧光素报告基因结果显示,过表达EHD2 和EHD2-3×NLS抑制Wnt 信号通路活性。而siRNA敲降则获得相反的结果。免疫共沉淀和Duolink-PLA实验证明,EHD2与Wnt信号通路关键分子β-连环蛋白(β-catenin)和T细胞因子3(T-cell factor 3,TCF3)相互作用。蛋白质印迹和荧光定量PCR结果证实,过表达EHD2 和EHD2-3×NLS抑制TCF3下游与增殖和细胞周期相关的靶基因的转录,以及细胞周期蛋白D1(cyclin D1)、细胞周期蛋白激酶4(CDK4)和pRb的蛋白质表达。以上结果表明,核EHD2与β-catenin和TCF3 复合体相互作用,通过Cyclin D1-CDK4-pRb信号轴来调控食管鳞癌细胞的增殖和细胞周期进程。     

Novel Functions for Cell Cycle Genes in Nervous System Development

Many cell cycle genes are known to play important roles in regulating proliferation in the nervous system, however, a growing body of research has proposed that these genes have diverse functions beyond cell cycle regulation. Through the study of new genetic models, cell cycle regulatory genes have been shown to impact on a number of processes during nervous system development including apoptosis, differentiation, and, most recently, neuronal migration. Here we emphasize that the proposed roles for cell cycle genes in neuronal differentiation and migration are not the consequence of deregulated cell cycle, but represent truly novel functions for cell cycle genes.