PC12细胞诱导的神经缺血细胞Smad7-siRNA及沉默效果的检测

目的探讨诱导PC12细胞分化的神经细胞靶向沉默Smad7基因特性,同时进行沉默效果检测.方法以Smad7基因为靶目标,设计合成3条siRNA序列,进行细胞转染,利用Real time-PCR和Western blot技术检测沉默效果,筛选出最有效的干扰序列,同时检测出最佳的转染浓度和转染时间.结果针对Smad7基因设计合成及筛选出靶向沉默Smad7基因的干扰序列(siRNA1);siRNA1的最佳转染浓度是4μg/mL;siRNA1的最佳转染时间是24 h;siRNA1对Smad7的抑制效果优于其他干扰序列.结论 siRNA1能有效沉默Smad7基因;lipofectamineTM2000可成功将siRNA1转染至神经细胞,转染效率较高;利用siRNA技术能有效抑制神经细胞.     

在Hep G2细胞中利用siRNA沉默GFP基因的实验探讨

目的:通过探讨小分子双链RNA(siRNA)通过RNA干扰(RNAi)机制沉默肝癌细胞株Hep G2荧光素报告基因GFP的各项生物学指标,为进一步实验和临床研究提供依据.方法:通过体外实验,对siRNA和siRNA脂质体的稳定性和细胞毒性进行评估;通过荧光标记技术,研究不同时间siRNA脂质体的转染效率;通过荧光显微镜下观察转染细胞和RT-PCR检测靶基因mRNA表达,确定不同种类、形式、剂量的siRNA对靶基因的沉默效能.结果:在空白培养液中,siRNA和siRNA脂质体可稳定至4h,在5%血清中2～4h后明显降解;100nM的siRNA和siRNA脂质体无明显细胞毒性;siRNA脂质体转染细胞株的效率随时间不同而不同,4h可达90%;非特异性siRNA/脂质体无沉默靶基因表达作用,特异性siRNA/脂质体对靶基因的沉默作用在一定范围内随剂量升高(20nM、50nM、100nM)而升高.结论:siRNA的稳定性可满足实验需要,且无明显细胞毒性,特异性siRNA转染肝癌细胞株能有效抑制靶基因表达,用脂质体转染可提高转染效率.siRNA通过RNAi机制沉默靶基因表达,为肿瘤的治疗和基础研究提供了新的工具和思路.     

以多药耐药基因为靶标的siRNA对耐药肿瘤细胞药物敏感性和凋亡的影响

目的:研究应用以多药耐药相关蛋白(MRP)基因为靶标的siRNA( small interference RNA) 抑制相应蛋白表达后,耐药肿瘤细胞药物敏感性和凋亡率的改变.方法:通过脂质体将以MRP基因为靶标的siRNA(100 μmol/L)转入柔红霉素(DNR)0.8、1.6、3.2、6.4、12.8 μg/mL处理的肺癌耐药细胞株SW1573/R20;阿霉素(ADM)1.6、3.2、6.4、12.8、25.6 μg/mL处理的白血病耐药细胞株K562/ADM;顺铂(DDP)0.125、0.25、0.5、1.0、2.0、4.0 μmol/mL处理的鼻咽癌耐药细胞株CNE2/DDP;以单纯化疗处理组和未处理组为对照.于转染后24、48、72h,用MTT法检测各组细胞生长抑制率,算出各细胞IC50.转染siRNA联合IC50剂量化疗处理6 h后流式细胞仪检测各细胞凋亡率和死亡率,24 h后RT-PCR检测相应基因mRNA表达水平,48 h后检测MRP蛋白表达率.结果:以MRP为靶标的siRNA 明显抑制各肿瘤细胞靶基因蛋白和mRNA的表达,与未处理组相比均有统计学差异(P＜005);转染以MRP为靶标的siRNA后,耐药肿瘤细胞对化疗药物敏感性明显增强,IC50明显降低,细胞凋亡率明显增加,与单纯化疗组相比有统计学差异(P＜005).结论:以MRP基因为靶标的siRNA,通过降低靶基因mRNA和蛋白表达,明显增加耐药肿瘤细胞药物敏感性和凋亡率.     

靶向肿瘤多药耐药基因mdr1的siRNA的构建与鉴定

mdr 1基因及其表达产物P-gp是引起肿瘤细胞多药耐药(MDR)的主要原因,抑制mdr 1基因的表达可用于逆转MDR.RNAi可用于特异抑制靶基因的表达,本研究的目的是构建获得可特异有效靶向mdr 1基因的siRNA元件.应用siRNA设计软件与mRNA结构分析软件设计构建了3个分别靶向mdr 1基因mRNA环结构和茎结构的siRNA元件,同时构建了携带mdr1基因序列的luc报告质粒,通过siRNA表达质粒与携带靶序列的报告质粒的共转染抑制实验检测不同siRNA的抑制效率,结果显示靶向环结构siMDR1B具有较好的抑制效率和特异性.进一步将siMDR1B表达载体与mdr1基因表达载体共转染细胞,应用免疫流式细胞术检测显示,相比对照细胞,siMDR1B可显著抑制其转染后mdr1基因产物P-gp蛋白的表达活性.同时采用CCK-8细胞活性检测试剂评价了siMDR1B对细胞活性的影响,结果显示siMDR1B不会影响细胞活性,具有良好的特异性.本研究获得的可有效靶向mdr 1基因的siRNA元件可为进一步开展逆转MDR研究提供重要基础.     

BGC-823细胞中慢病毒途径针对HIF-1α基因的RNAi实验

目的：构建人HIF-1α基因的shRNA慢病毒载体、包装生产重组慢病毒颗粒,病毒途径高效感染胃癌细胞株BGC-823,并验证基因沉默效率。方法：在NCBI数据查找人HIF-1α基因序列,然后使用siRNA在线设计软件,设计针对基因CDS区的3条siRNA序列及Negative序列。根据设计好的siRNA序列设计双链互补的shRNA-Oligo DNA,退火形成双链后与线性化载体链接,构建shRNA重组表达载体。经由293TN细胞包装shRNA重组慢病毒颗粒,随后使用重组病毒感染BGC-823,通过荧光标记蛋白GFP确定感染效率后收集细胞样本,分别采用Real-time PCR和Western blot方法检测靶基因在mRNA和蛋白质水平的沉默效率。结果：shRNA重组表达载体测序结果与设计序列完全一致,包装病毒后滴度达到1×104 ifu/μL。慢病毒感染BGC-823细胞取得了极高的基因转导效率。mRNA检测结果显示,siRNA3对于对与目的基因的沉默效果最好,较阴性对照序列组相比较,mRNA的表达量下降了92%,Western blot检测的结果与mRNA检测结果完全相符合。结论：通过慢病毒途径,可以在BGC-823细胞中高效的进行HIF-1α基因的沉默。     

大鼠CRMP1基因siRNA的筛选

目的:筛选有效抑制大鼠CRMP1基因表达的siRNA序列.方法:化学合成3对针对大鼠CRMP1基因的特异性siRNA,用脂质转染胺(lipofectamine)LTX转染大鼠海马神经元,通过流式细胞仪检测转染效率,使用RT-PCR与实时 PCR检测CRMP1基因mRNA的表达,从而筛选抑制效率最高的siRNA.结果:流式细胞仪检测转染效率为52.5%.通过RT-PCR的初步检测和实时 PCR的定量检测结果显示,与对照组相比,所设计的3对siRNA均能不同程度抑制CRMP1基因mRNA的表达,其中CRMP1-249 siRNA抑制效果最佳,抑制率达84.3%.结论:成功筛选出1对能有效抑制大鼠CRMP1基因表达的siRNA序列.     

腺病毒介导的TRF2 RNAi表达载体诱导MCF-7细胞凋亡的研究

选择针对人TRF2 mRNA的特异性siRNA靶序列,设计、合成其相应的双链DNA,并构建成表达siRNA-TRF2的重组腺病毒载体rAd-shRNA-TRF2,转染人乳腺癌MCF-7细胞,以Western印迹法检测MCF-7细胞TRF2蛋白表达、MTT比色法绘制MCF-7细胞生长曲线、流式细胞仪检测细胞凋亡情况.实验结果表明:重组腺病毒载体rAd-shRNA-TRF2构建成功,转染MCF-7细胞后可明显抑制TRF2基因的表达,并抑制细胞增殖、诱导细胞凋亡.说明通过RNAi技术抑制TRF2基因表达,进而诱导肿瘤细胞凋亡可能用于肿瘤的基因治疗.     

蛋白质的二级结构和mRNA的二级结构的相关性研究

利用置信度为95的特征字研究了蛋白质二级结构以及其对应mRNA二级结构，发现蛋白质二级结构和mRNA二级结构有明显的相关性。规则二级结构α—螺旋，β—折叠以及包含有Turn的边界明显倾向于mRNA二级结构的茎区，而避免出现在环区。     

BCR/ABL和SEA双基因重组载体的构建和表达

目的:构建和表达含BCR/ABL融合基因和葡萄球菌肠毒素A(SEA)的真核双表达质粒.方法:利用RT-PCR技术从K562细胞中扩增出含BCR/ABL融合位点基因片段,提取金黄色葡萄球菌基因组DNA扩增出SEA基因,分别将两基因片段连在pIRES载体的多克隆位点A和B上,构建BCR/ABL-pIRES-SEA、SEA- pIRES-BCR/ABL重组质粒.将重组质粒转染K293细胞,RT-PCR鉴定重组质粒在真核细胞的转录情况, SDS-PAGE电泳鉴定目的蛋白在真核细胞的表达.结果:成功扩增出BCR/ABL和 SEA基因片段;双酶切鉴定BCR/ABL-pIRES-SEA、SEA-pIRES-BCR/ABL重组质粒中含有BCR/ABL和SEA基因,测序证实完全正确;将重组质粒转染K293细胞后,经 RT-PCR扩增鉴定,插入到重组质粒的BCR/ABL和SEA基因能在真核细胞正常转录,经SDS-PAGE电泳鉴定重组质粒能够在真核细胞中表达BCR/ABL和SEA蛋白.结论:成功构建BCR/ABL-pIRES-SEA、SEA-pIRES-BCR/ABL真核双表达质粒,可在真核细胞中正常转录并表达BCR/ABL和SEA蛋白.     

3-MA 对阿霉素诱导 K562、K562 / ADM 细胞凋亡及其相关基因 mRNA 表达的影响

目的：通过自噬抑制剂3-甲基腺嘌呤（3-MA）对阿霉素（ADM）诱导白血病K562细胞及K562／ADM细胞的细胞效应和自噬基因Beclinl、凋亡抑制基因SurvivinmR．NA表达的变化观察,探讨自噬在细胞凋亡中的作用和机制．方法：体外培养K562和K562／ADM细胞,采用MTT法分别检测ADM及3-MA预处理对K562、K562／ADM细胞增殖的影响,流式细胞仪检测细胞凋亡率,实时RT—PCR法检测细胞自噬及凋亡相关基因（Beclinl、Survivin）mRNA表达的变化．结果：ADM可抑制K562与K562／ADM细胞增殖,且抑制作用呈现浓度与时间依赖性．ADM诱导组K562与K562／ADM细胞在24h、48h、72h细胞凋亡率均较空白对照组明显提高（P〈0．05）．在ADM诱导前,经3-MA预处理可使ADM诱导的K562与K562／ADM细胞抑制率和细胞凋亡率均较单用ADM显著提高（尸〈0．05）,Bedin1、SurvivinmRNA相对表达量均较单用ADM明显下降（P〈0．05）,呈正相关（r=0．827,P〈0．01）．结论：ADM可抑制K562、K562／ADM细胞的生长,并诱导细胞凋亡．3-MA通过抑制细胞的自噬可增强ADM诱导白血病细胞K562、K562／ADM的凋亡,其机制可能与下调BeclinlmRNA表达,而使Survivin表达受抑制有关．     

Quantification of mRNA by RT-competitive-PCR and high performance liquid chromatography

The use of RT-competitive-PCR with high performance liquid chromatography (HPLC) detection to quantify the absolute number of mRNA copies in mammalian cells is reported. As an example, the glutathione transferase (GST)-α mRNA in human hepatoma Hep G2 cells has been estimated. A PCR-generated internal standard was used as a competitor, co-amplified with the GST-α target sequence. The RT-competitive-PCR method was improved by designing target and competitor molecules which differed in only 30 base pairs. This allowed the two sequences to be co-amplified with the same efficiency. This improvement also facilitated a wider ratio to be used than previous methods (target:competitor ratio between 0.2 and 5). Products were baseline separated by HPLC using an ion-exchange column readily quantified at 260 nm. To validate the improved methodology, the effect of a known GST-α inducer, the anticancer drug oltipraz, was shown to induce GST-α mRNA up to 3-fold in Hep G2 cells. The RT-competitive PCR-HPLC method provides a reliable and sensitive way to quantify the amount of specific mRNA with 0.1 ng of total RNA.     

Chronic lymphocytic leukaemia is driven by antigen-independent cell-autonomous signalling

B-cell antigen receptor (BCR) expression is an important feature of chronic lymphocytic leukaemia (CLL), one of the most prevalent B-cell neoplasias in Western countries. The presence of stereotyped and quasi-identical BCRs in different CLL patients suggests that recognition of specific antigens might drive CLL pathogenesis. Here we show that, in contrast to other B-cell neoplasias, CLL-derived BCRs induce antigen-independent cell-autonomous signalling, which is dependent on the heavy-chain complementarity-determining region (HCDR3) and an internal epitope of the BCR. Indeed, transferring the HCDR3 of a CLL-derived BCR provides autonomous signalling capacity to a non-autonomously active BCR, whereas mutations in the internal epitope abolish this capacity. Because BCR expression was required for the binding of secreted CLL-derived BCRs to target cells, and mutations in the internal epitope reduced this binding, our results indicate a new model for CLL pathogenesis, with cell-autonomous antigen-independent signalling as a crucial pathogenic mechanism.     

Knockdown of <Emphasis Type="Italic">MRP4</Emphasis> by lentivirus-mediated siRNA improves sensitivity to adriamycin in adriamycin-resistant acute myeloid leukemia cells

Chemotherapy remains the standard treatment for acute myeloid leukemia;however,the emergence of drug resistance is a major hurdle in the successful treatment of leukemia.The expression of multidrug resistance-associated protein 4(MRP4)induces re- sistance in the adriamycin-resistant acute myeloid leukemia cell line,K562/ADR.The aim of this study was to investigate whether knockdown of MRP4 by lentivirus-mediated siRNA could improve the sensitivity of K562/ADR cells to adriamycin.Five lenti- virus-mediated short hairpin RNAs(lv-shRNAs-MRP4)were designed to trigger the gene silencing RNA interference(RNAi) pathway.The efficiency of lentivirus-mediated siRNA infection into K562/ADR cells was determined using fluorescence mi- croscopy to observe lentivirus-mediated GFP expression.MRP4 expression in infected K562/ADR cells was evaluated by real- time PCR and Western blot analysis.The MTS assay was used to measure cell viability and flow cytometry was used to measure apoptosis.The transfection efficiency of K562/ADR cells was over 80 percent.The gene silencing efficacy of lv-shRNA1-MRP4 was superior to the other constructs.Infection of K562/ADR cells with lv-shRNA1-MRP4 led to strong inhibition of MRP4 mRNA and protein expression.Combined treatment with lv-shRNA1-MRP4 and adriamycin decreased cell growth and increased apoptosis compared to treatment with lv-shRNA1-MRP4 or adriamycin alone.These data indicate that in K562/ADR cells MRP4 is involved in drug resistance mechanisms and that lentivirus-mediated knockdown of MRP4 may enhance sensitivity to adriamycin.     

以bcl-2为靶标siRNA-2提高HL-60细胞对阿糖胞苷的敏感性

目的:研究以bc l-2基因为靶标有效siRNA-2(sm all interference RNA)能否提高HL-60细胞对阿糖胞苷(Ara-C)的敏感性。方法:将siRNA-2转入HL-60细胞株并与Ara-C联合培养,于24、48、72 h,用MTT法检测细胞增殖生长,用流式细胞仪检测HL-60细胞bc l-2蛋白的表达率、细胞内活性氧(ROS)水平变化及细胞线粒体膜电位的变化。结果:siRNA-2明显提高HL-60细胞对Ara-C敏感性;抑制细胞bc l-2蛋白的表达,提高细胞内ROS水平,降低线粒体膜电位(P<0.05)。结论:siRNA-2能提高白血病细胞HL-60对Ara-C敏感性。     

PTTG基因对人垂体瘤细胞侵袭能力的影响

目的：本研究的目的在于PITG基因过表达及沉默对人垂体瘤细胞侵袭力的影响,探讨其与垂体瘤细胞侵袭性的关系及调控机制。方法：用脂质体转染携带PTTG基因的表达质粒,构建过表达PTTG基因的垂体细胞株,观察细胞形态。另外我们运用脂质体转染PITGsiRNA对垂体瘤中的PITG基因进行干扰;利用Western blot技术检测其基沉默效应;通过Transwell小室法测定垂体瘤细胞侵袭能力的改变。结果：转染PITG siRNA后,垂体瘤细胞中PTIG的mRNA转录和蛋白表达受抑,显著低于未经处理的垂体瘤细胞（P〈0.01）。利用PTTGsiRNA对PTTG进行RNA干扰后,垂体瘤细胞的侵袭能力下降。结论：（1）在正常垂体细胞中过表达PTTG基因也可以引起细胞癌变,增强侵袭能力。（2）设计的PTTG siRNA能有效抑制体外培养垂体瘤细胞中PTTG的mRNA转录和蛋白表达水平,实现其基因沉默效应。PTTG与人垂体瘤的侵袭能力密切相关,其表达水平下降导致细侵袭能力降低。     

siRNA分子设计研究进展

为了设计高效的siRNA（Short interfering Ribonucleic Acid）分子、最大限度地减少siRNA分子的脱靶效应（off-target effects），siRNA分子设计已经成为热门研究领域。siRNA分子设计主要是基于序列和能量特征，以及靶标的二级结构特征，基于这些特征设计的siRNA分子已经有了较高的抑制基因表达的效率。RNAi（RNA interference）在
基因发现以及疾病治疗领域已有非常广泛的应用，就siRNA分子设计近年的研究进展作一综述，为今后siRNA研究提供参考。     

Nucleotide sequence of cloned cDNA of human c-myc oncogene

Like other transforming genes of retroviruses, the v-myc gene of the avian virus, MC29, has a homologue in the genome of normal eukaryotic cells. The human cellular homologue, c-myc, located on human chromosome 8, region q24 leads to qter (refs 1, 2), is translocated into the immunoglobulin heavy-chain locus on human chromosome 14 (ref. 3) in Burkitt's lymphoma, suggesting that c-myc has a primary role in transformation of some human haematopoietic cells. In addition, c-myc is amplified in the human promyelocytic leukaemia cell line, HL60 (refs 6, 7) which also contains high levels of c-myc mRNA. Recently, Colby et al. reported the nucleotide sequence of the human c-myc DNA isolated from a genomic recombinant DNA library derived from human fetal liver. This 4,053-base pair (bp) sequence includes two exons and one intron of the myc gene, and the authors have suggested the existence of a human c-myc mRNA of 2,291 nucleotides that has a coding capacity for a protein of molecular weight (Mr) 48,812. We have approached the problem of accurately defining the characteristics of the human c-myc mRNA and c-myc protein by determining the sequence of the c-myc cDNA isolated from a cDNA library prepared from mRNA of a clone of the K562 human leukaemic cell line. K562 cells are known to contain c-myc mRNA which is similar in size to the c-myc mRNA of other human cell types. We report here the sequence of 2,121 nucleotides of a human c-myc mRNA and demonstrate that its 5' noncoding sequence does not correspond to the sequence of the reported genomic human sequence. However, our data confirm that the intact human c-myc mRNA can encode a 48,812-Mr protein with a sequence identical to that reported by Colby et al.     

siRNA对肺癌细胞株NCI-H460 bcl-2基因表达的影响

目的:研究siRNA (smallinterferenceRNA)对大细胞肺癌细胞株NCI -H4 6 0bcl- 2基因表达的影响。方法:利用Ambion公司提供的设计软件和试剂盒,设计合成以bcl - 2基因为靶标的siRNA ,通过脂质体将合成的siRNA转入NCI-H4 6 0细胞株,设置转染bcl- 2反义药物G3139和空白两对照组。用MTT法检测siRNA对细胞生长的作用;流式细胞仪检测细胞周期的改变和Bcl- 2蛋白表达;RT -PCR检测bcl- 2mRNA水平。结果:siRNA组与对照组细胞存活率均有显著性差异(P <0 0 5 ) ;siRNA组bcl- 2的mRNA明显低于对照组和反义组(P <0 0 5 ) ;siRNA组Bcl- 2蛋白阳性率明显低于对照组和反义组,siRNA组以及反义组细胞阻滞于S期。结论:体外转录合成的siRNA可抑制NCI-H4 6 0细胞bcl- 2基因的表达,抑制率可达5 0 %以上。