Involvement of anoikis-resistance in the metastasis of hepatoma cells

Acquisition of anoikis-resistance is a pre-requisite for cancer cell metastasis. We have demonstrated that hepatoma cells could resist anoikis by a synoikis-like survival style. In this study, we further suggest that acquisition of anoikis-resistance confer cancer cells more capacity for invasiveness, evading from cancer therapeutic agents and escaping from host immune attacks. We investigated the response of anoikis-resistant hepatoma cells to TNF-related apoptosis-inducing ligand (TRAIL), a typical immune surveillant molecule as well as a potential anticancer agent. Our data indicated that detached hepatoma cells not only resist TRAIL-induced apoptosis, but also domesticate TRAIL to exert a stealth “tumor counterattack” effect. These results reveal that acquisition of anoikis-resistance may act as a selective pressure to superimpose on hepatoma cells more metastatic potential for the development of cancer.     

HBV DNA can bind to P53 protein and influence p53 transactivation in hepatoma cells

Hepatitis B virus (HBV) may contribute to hepatocarcinogenesis by blocking p53 function. A p53 response element-like binding sequences, TGCCT?TGCCT, was found in HBV genome. To clarify whether HBV DNA can, like some other DNA viruses, bind to P53 protein and form a DNA-protein complex, we used a series of plasmids encoding full-length or mutant HBV or p53 fragments to determine the binding ability of HBV DNA after cotransfected into cells by electrophoretic mobility shift (and supershift) assay. We found that HBV DNA could bind to P53 protein and form DNA-protein complexes in human hepatoma cell lines. Cotransfection with p53 and HBV DNA increased the replication of HBV, CAT activity, tumor cell apoptosis, and cytoplasmic P53 accumulation in the hepatoma cells. In conclusions, our observations suggest that the interaction of HBV and p53 at the levels of protein-protein and DNA-protein, which resulted in inactivation of p53 transactivation.     

IGF2基因组印迹系统人重组腺病毒载体的构建与鉴定

目的:构建携带IGF2印迹系统的腺病毒载体,并验证其在肿瘤细胞及正常细胞中的功效,为IGF2印迹在肿瘤靶向治疗中的应用提供理论基础.方法:将人源的IGF2印迹系统启动子H19、增强子enhancer及甲基化区域CTCF克隆至穿梭质粒pDC-312中构建IGF2基因印迹系统,从pDC-315-EGFP质粒中扩增出EGFP片段插入到构建好的IGF2印迹系统中,然后与腺病毒骨架Ad5通过脂质体Lipofectamine2000介导共转染HEK293细胞,包装成有感染能力的腺病毒Ad-H19-CTCF-enlmncer-EGFP,命名为Ad-EGFP;构建好的腺病毒分别感染IGF2基因印记保持的细胞MCF-7和GES-1及IGF2基因印迹丢失的细胞HRT-18,荧光显微镜下观察EGFP在三种细胞中表达的差异.结果:转染腺病毒载体的HEK293细胞表达EGFP随着时间逐渐增强,并且出现明显的细胞病变效应,EGFP在HRT-18细胞中有大量表达,在MCF-7和GES-1细胞中不表达或仅有少量表达.结论:成功构建了携带IGF2基因印迹系统的腺病毒载体,证明其在IGF2基因印迹丢失的肿瘤细胞中特异性的表达,在正常细胞及IGF2基因印迹保持细胞中不表达,为IGF2基因印迹系统应用于肿瘤细胞的靶向治疗提供了理论基础.     

Genome-Wide Analysis of Small RNA and Novel MicroRNA Discovery in Human Acute Lymphoblastic Leukemia Based on Extensive Sequencing Approach

Background

MicroRNAs (miRNAs) have been proved to play an important role in various cellular processes and function as tumor suppressors or oncogenes in cancers including leukemia. The identification of a large number of novel miRNAs and other small regulatory RNAs will provide valuable insights into the roles they play in tumorgenesis.

Methodology/Principal Findings

To gain further understanding of the role of miRNAs relevant to acute lymphoblastic leukemia (ALL), we employed the sequencing-by-synthesis (SBS) strategy to sequence small RNA libraries prepared from ALL patients and normal donors. In total we identified 159 novel miRNAs and 116 novel miRNA*s from both libraries. Among the 159 novel miRNAs, 42 were identified with high stringency in our data set. Furthermore, we demonstrated the different expression patterns of 20 newly identified and several known miRNAs between ALL patients and normal donors, suggesting these miRNAs may be associated with ALL and could constitute an ALL-specific miRNA signature. Interestingly, GO “biological process” classifications revealed that a set of significantly abnormally expressed miRNAs are associated with disease relapse, which implies that these dysregulated miRNAs might promote the progression of ALL by regulating genes involved in the pathway of the disease development.

Conclusion/Significance

The study presents a comprehensive picture of the expression of small RNAs in human acute lymphoblastic leukemia and highlights novel and known miRNAs differentially expressed between ALL patients and normal donors. To our knowledge, this is the first study to look at genome-wide known and novel miRNA expression patterns in in human acute lymphoblastic leukemia. Our data revealed that these deregulated miRNAs may be associated with ALL or the onset of relapse.     

细菌群体感应系统的研究

群体感应是细菌根据细胞密度变化进行基因表达调控的一种生理行为.细菌通过群体感应与周围环境进行信息交流,参与多种生理过程.就细菌群体感应系统的组成、作用机制、类型、特点及细菌中群体感应的最新进展作以综述.