MDM2基因敲低对白血病细胞株K562的影响

[目的]研究MDM2基因对白血病细胞的影响,探讨MDM2基因在白血病发病机制和治疗方面的意义.[方法]用pSilencer4.1-CMV neo构建MDM2 shRNA表达载体pMDM2-shRNA,采用脂质体将载体导入K562细胞,G418筛选出稳定表达shRNA细胞,然后用在流式细胞仪检测细胞周期变化和细胞凋亡率,用多重RT-PCR和Western blot检测细胞基因表达水平.[结果]转染pMDM2-shRNA的细胞MDM2 mRNA及蛋白质的表达均下降＞70%,细胞增殖减慢,G1-S期阻滞,细胞凋亡增加.伴随MDM2基因表达下调,多种基因表达出现较明显改变,包括P21表达增加,E2F1和P65表达下降.[结论]MDM2基因表达下降后,可导致细胞增殖减慢和细胞凋亡;结果表明MDM2对多种基因的表达具有调控作用,提示MDM2有可能成为白血病治疗的新靶点.     

RNAi下调PIK3 CB表达抑制U251胶质瘤细胞生长的体内外研究

目的 探讨应用RNAi技术靶向磷酸肌醇酯-3-激酶β催化亚单位(PIK3CB)抑制恶性胶质瘤细胞系U251的PIK3CB表达后在体内外对U251细胞生长抑制作用.方法 将短发夹RNA(shRNA)表达载体psiRNA-PIK3CB进行脂质体介导的U251人脑恶性胶质瘤细胞系表达,检测细胞转染前后的细胞增殖能力和凋亡的变化.应用裸鼠皮下荷瘤模型观察脂质体介导shRNA基因治疗对U251细胞生长抑制作用,对肿瘤组织应用免疫荧光双染色和免疫组化的方法分析结果.结果 靶向PIK3CB的shRNA转染后U251细胞生长受到抑制,细胞周期出现G2/M阻滞,细胞明显凋亡.裸鼠皮下荷瘤模型实验显示psiRNA-PIK3CB显著抑制皮下肿瘤生长(P＜0.01).结论 靶向PIK3CB的shRNA基因治疗可以成为胶质瘤治疗的新策略.     

靶向HIWI基因的shRNA真核表达载体的构建及鉴定

目的构建靶向HIWI基因的shRNA真核表达载体质粒，为利用RNA干扰技术探索HIWI基因的作用的研究做准备。方法根据HIWI mRNA序列设计并合成shRNA寡核苷酸片段，退火形成双链并连接入pGenesil-2载体，并进行酶切鉴定和测序。结果酶切证明构建的shRNA已插入载体中，经测序证明与设计相同。结论成功构靶向HIWI基因的shRNA真核表达载体，为进一步研究HIWI基因在干细胞和肿瘤细胞中的作用机制及后续的体内外RNAi实验研究奠定了基础。     

PEGFP-C1/U6质粒载体介导的表达MDR1 shRNA的质粒构建

为了构建pEGFP-C1／U6载体介导MDR1短发卡RNA（short hairpin RNA，shRNA）表达的质粒，针对MDR1的19碱基大小的片段．分别设计2对寡核苷酸，形成双链后将其依次连入带有U6启动子的pEGFP-C1载体（命名为pEGFP-C1／U6），两对DNA双链连接后形成中间由9个碱基序列间隔的反向互补序列，构建成能产生MDR1短发卡RNA的质粒。结果表明：经酶切、连接后构建成的质粒（pEGFP-C1／U6／A和pEGFP-C1／U6／B），经酶切与测序证实构建成功，无任何碱基突变。结论：成功构建了能表达MDR1 shRNA的质粒栽体pEGFP-C1／U6／A和pEGFP-C1／U6／B，此项研究结果可能为临床上逆转肿瘤多药耐药提供一种有效的方法。     

FOXP3 shRNA3对肝癌细胞趋化因子及受体CXCL12、CXCL11、CXCR4、CXCR7作用的研究

目的研究FOXP3 shRNA对肝癌细胞株SMMC-7721和MHCC-97H的趋化因子及受体CXCL12、CXCL11、CXCR4、CXCR7的影响。方法设计三种编码FOXP3 shRNA的FOXP3干扰慢病毒,sh-FOXP3-1-pGreenPuro、sh-FOXP3-2-pGreenPuro和sh-FOXP3-pgreenpuro并分别转染SMMC-7721和MHCC-97H细胞。q-PCR检测各组CXCL12、CXCL11、CXCR4、CXCR7 mRNA的表达情况;Western Blot检测各组CXCL12、CXCL11、CXCR4、CXCR7蛋白的表达情况。结果经菌落PCR和测序验证证明三个FOXP3干扰慢病毒载体构建正确;三种干扰序列中sh-FOXP3-1干扰效果最明显,因此后期实验都使用sh-FOXP3-1进行下面的实验。研究显示:(1)与对照组相比,sh-FOXP3-1组的CXCL12、CXCL11、CXCR4、CXCR7 mRNA表达明显下降,差异具有统计学意义。(2)与对照组相比,sh-FOXP3-1组的CXCL12、CXCL11、CXCR4、CXCR7蛋白表达明显下降,差异具有统计学意义。结论干扰FOXP3的表达后,能减少趋化因子CXCL12、CXCL11、CXCR4、CXCR7的表达。     

Interference of lysine-specific demethylase 1 inhibits cellular invasion and proliferation in vivo in gastric cancer MKN-28 cells

BackgroundLysine-specific demethylase 1(LSD1), the first identified histone demethylase, plays an important role in the epigenetic regulation of gene activation and repression. Up-regulated LSD1expression has been reported in several malignant tumors.Our aim, therefore, was to better understand the mechanisms underlying the upregulation of LSD1 in gastric cancer.MethodsWe used lentiviral shRNA to knockdown LSD1 in the gastric cancer MKN-28 cell line. Cell proliferation was measured by MTT assay while cell apoptosis was assessed by Annexin V-FITC/PI double staining flow cytometry. The invasive potential of gastric cancer cells was determined by matrigel invasion assay. Protein expression was detected by Western blot. In vivo, the effect of knocking down LSD1 on tumor growth and protein expression in gastric cancer cells in nude mice was investigated.ResultsLSD1 knockdown in MKN-28 cell lines resulted in increasing the activity of cisplatin in vitro and the inhibition of cancer cell proliferation and invasion, and induced cell apoptosis. The expression of TGF-β1, VEGF, Bcl-2, β-catenin, p-ERK and p-Smad 2/3 proteins was inhibited in LSD1 knockdown cells. Moreover, in an in vivo model of gastric cancer, LSD1 knockdown suppressed tumor growth and protein expression.ConclusionLSD1 knockdown affected the fuction of gastric cancer MKN-28 cell line. LSD1 may be a latent target in the diagnosis and therapy of gastric cancer.     

人BNIP3真核表达载体和shRNA表达载体的构建及其对肝癌细胞自噬的影响

目的利用人BNIP3的真核表达载体和靶向BNIP3的shRNA表达载体,研究BNIP3过表达和封闭时对肝癌细胞自噬的影响。方法从人肝癌细胞系中,通过RT-PCR扩增人BNIP3基因编码区序列,酶切后插入pcDNA3.1-His-C载体,以此构建重组pcDNA3.1-BNIP3真核表达载体。同时构建靶向人BNIP3基因的shRNA表达载体pSilencer-BNIP3。分别经测序、酶切、RT-PCR和Western blot等方法对重组载体是否构建成功进行验证。并通过采用Western blot检测自噬标志物LC3蛋白的剪切,研究BNIP3过表达和抑制时对肝癌细胞自噬的影响。结果pcDNA3.1-BNIP3和pSilencer-BNIP3分别过表达BNIP3和抑制BNIP3的表达。BNIP3过表达能够显著增加肝癌细胞的自噬;BNIP3表达受到抑制时,肝癌细胞的自噬明显减少。结论成功构建了人BNIP3的真核表达载体pcDNA3.1-BNIP3和shRNA表达载体pSilencer-BNIP3,并在人肝癌细胞系中证实BNIP3对肝癌细胞自噬的促进作用。     

CCR4 dependent migration of Foxp3+ Treg cells to skin grafts and draining lymph nodes is implicated in enhanced graft survival in CD200tg recipients

We have previously reported that transgenic overexpression of CD200 in either mouse skin graft donors or recipients significantly enhances skin allograft survival. By focused microarray analysis we showed this enhanced graft survival is associated with increased expression of Foxp3, GITR, CTLA-4 and CCR4 mRNA, all genes related to T_reg cell induction/function, and of Gata3, IL-4, IL-5, IL-13, and somewhat surprisingly, of T-bet, INF-γ and granzyme b. Gene-specific real-time PCR and immunohistochemistry analysis confirmed an increase in Foxp3⁺ T_reg cells in both the skin grafts and draining lymph nodes (DLNs) of CD200^tg recipient mice at both 7/14 days post engraftment, as well as providing evidence for increased expression of the ligands for CCR4, CCL17 and CCL22 in both locations. Following lentivirus-mediated shRNA treatment of Dox-treated CD200^tg mice to attenuate expression of CCR4 mRNA, the increased localization of T_reg cells in skin/DLN of CD200^tg recipients was abolished, and the enhanced graft survival similarly reversed. We conclude that enhanced CCR4 dependent migration of Foxp3⁺ T_reg to grafted tissue and DLNs is an essential step in the graft prolongation afforded by overexpression of CD200.     

Multidrug resistance protein (MRP) 4 attenuates benzo[a]pyrene-mediated DNA-adduct formation in human bronchoalveolar H358 cells

Multi-drug resistance protein (MRP) 4, an ATP-binding cassette (ABC) transporter, has broad substrate specificity. It facilitates the transport of bile salt conjugates, conjugated steroids, nucleoside analogs, eicosanoids, and cardiovascular drugs. Recent studies in liver carcinoma cells and hepatocytes showed that MRP4 expression is regulated by the aryl hydrocarbon receptor (AhR) and nuclear factor E2-related factor 2 (Nrf2). The AhR has particular importance in the lung and is most commonly associated with the up-regulation of cytochrome P-450 (CYP)-mediated metabolism of benzo[a]pyrene (B[a]P) to reactive intermediates. Treatment of H358, human bronchoalveolar, cells with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or (−)-benzo[a]pyrene-7,8-dihydro-7,8-diol (B[a]P-7,8-dihydrodiol), the proximate carcinogen of B[a]P, revealed that MRP4 expression was increased compared to control. This suggested that MRP4 expression might contribute to the paradoxical decrease in (+)-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene-2′-deoxyguanosine ((+)-anti-trans-B[a]PDE-dGuo) DNA-adducts observed in TCDD-treated H358 cells. We have now found that decreased MRP4 expression induced by a short hairpin RNA (shRNA), or chemical inhibition with probenecid, increased (+)-anti-trans-B[a]PDE-dGuo formation in cells treated with (−)-B[a]P-7,8-dihydrodiol, but not the ultimate carcinogen (+)-anti-trans-B[a]PDE. Thus, up-regulation of MRP4 increased cellular efflux of (−)-B[a]P-7,8-dihydrodiol, which attenuated DNA-adduct formation. This is the first report identifying a specific MRP efflux transporter that decreases DNA damage arising from an environmental carcinogen.