Trimeresurus flavoviridis (habu snake) venom induces human erythrocyte lysis through enzymatic lipolysis, complement activation and decreased membrane expression of CD55 and CD59

Trimeresurus flavoviridis (habu snake) bites can be fatal to man because of its virulent venom, which is clinicopathologically classified as haemorrhagic, necrotic, and haemolytic toxins. Trimeresurus flavoviridis venom causes lysis of human erythrocytes in conditions where plasma is present as well as in plasma-free conditions in a dose-dependent manner. The haemolytic process requires Ca2+ and Mg2+ ions in the solution. Additionally, the venom initiates activation of the human complement cascade as evidenced by C3a and C5a releases, complement consumption indicated by CH50 and formation of soluble membrane attack complex. The insertion of membrane attack complex into the erythrocyte membranes is morphologically identified by electronmicroscopy. Immunofluorescence analysis reveals that incubation of erythrocytes with the venom decreased cell-surface expression of CD55 (decay accelerating factor) and CD59 (protectin), which renders erythrocyte more vulnerable to adherent C3 and C5 convertases and to polymerization of C9 into membranes, and may enhance autologous complement-mediated haemolysis triggered by the venom. Our data demonstrate that Trimeresurus flavoviridis venom induces haemolysis in the presence of plasma by three distinct mechanisms, direct lipolysis through PLA2 activity, activation of the human complement system, and cleavages of CD55 and CD59 from erythrocyte membranes.     

Bcl-2 siRNA抑制HL-60细胞bcl-2基因表达

目的应用RNA干扰技术观察Bcl2siRNA对白血病细胞HL60中bcl2基因表达的影响,探讨siRNA技术在白血病治疗中的作用。方法利用化学合成法体外化学合成Bcl2siRNA,将Bcl2siRNA与HL60细胞共孵育,用MTT法、荧光染色观察细胞增殖及凋亡情况,用RTPCR检测Bcl2mRNA水平,用荧光染色测Bcl2蛋白水平。结果Bcl2siRNA与HL60细胞共孵育48h后,HL60细胞凋亡率增加,Bcl2mRNA水平下调,Bcl2蛋白表达水平降低。转染GAPDHsiRNA组的细胞对Bcl2表达无影响。结论Bcl2siRNA能够特异性降低Bcl2mRNA水平及蛋白质的表达,促进HL60细胞凋亡。     

Tannic acid, an inhibitor of poly(ADP-ribose) glycohydrolase, sensitizes ovarian carcinoma cells to cisplatin

Tannic acid (TA) has been associated with anticancer functions in multiple tumor types both in vitro and in vivo. However, its effect on ovarian carcinoma cells has not been investigated, and its underlying anticancer mechanism(s) remain unclear. In this study, the effects of TA alone and in combination with cisplatin were evaluated using ovarian carcinoma cell lines. Combined treatment with TA and cisplatin was found to induce apoptosis and increase DNA damage in the cisplatin-resistant (SKOV-3 CDDP/R) and cisplatin-sensitive (SKOV-3) human ovarian carcinoma cell lines, respectively. TA was also found to enhance the toxicity of cisplatin in ovarian carcinoma cells associated with the inhibition of poly(ADP-ribose) glycohydrolase (PARG) expression, increase the accumulation of poly(ADP-ribose) (pADPr), following the release of apoptosis-inducing factor, and the activation of caspase-3. In conclusion, as a PARG inhibitor, TA showed anticancer activity and increased the sensitivity of SKOV-3 cells and SKOV-3 CDDP/R cell lines to cisplatin.     

CD55、CD59、CD34对贫血的早期诊断研究应用

目的 探讨CD55、CD59、CD34抗原表达率对贫血的早期诊断及鉴别诊断意义,进而达到早期发现、早期诊断、早期预防治疗目的 .方法 应用流式细胞仪测定贫血病人及对照组粒细胞上CD55、CD59、CD34抗原表达率,并同时做相关血液学试验诊断,经过统计学处理,找出相关性.结果 表明PNH、AA、AA-pNH病人CD55、CD59、CD34抗原表达率较其他全血细胞减少症及正常对照组明显增高,而相互间有显著差异,P＜0.01或P＜0.05.结论 粒细胞上CD55、CD59、CD34抗原异常表达率可做贫血病人早期诊断及鉴别诊断指标,特别对血液病的AA、AA-PNI-I综合征、PNH有重要首选、敏感、特异诊断价值.     

Inhibition of c-Jun N-terminal kinase sensitizes tumor cells to flavonoid-induced apoptosis through down-regulation of JunD

Reduction of susceptibility to apoptosis signals is a crucial step in carcinogenesis. Therefore, sensitization of tumor cells to apoptosis is a promising therapeutic strategy. c-Jun NH2-terminal kinase (JNK) has been implicated in stress-induced apoptosis. However, many studies also emphasize the role of JNK on cell survival, although its mechanisms are not completely understood. Previously, we found that inhibition of JNK activity promotes flavonoid-mediated apoptosis of human osteosarcoma cells. We thus determined whether inhibition of JNK sensitizes tumor cells to a bioflavonoid-induced apoptosis, and whether this effect of JNK is a general effect. As the results, quercetin and genistein as well as a flavonoid fraction induced apoptosis of tumor cells, which was further accelerated by specific JNK inhibitor, SP600125 or by small interfering RNA specific to JNK1/2. This effect was specific to types of cells because it was further apparent in tumorigenic cell lines. Inhibition of JNK by SP600125 also reduced flavonoid-stimulated nuclear induction of JunD which was known to have protective role in apoptosis, whereas JNK inhibition alone had little effect on apoptosis. The flavonoid-induced apoptosis of tumor cells was significantly enhanced by transfecting them with antisense JunD oligonucleotides. These results suggest that inhibition of JNK facilitates flavonoid-induced apoptosis through down-regulation of JunD, which is further sensitive to tumor cells. Therefore, combination with a specific JNK inhibitor further enhances the anti-cancer and chemopreventive potential of bio-flavonoids.     

Butein sensitizes human leukemia cells to apoptosis induced by tumor necrosis factor-related apoptosis inducing ligand (TRAIL)

Resistance to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) therapy is frequently encountered, requiring combined treatments with sensitizing agents. It is, therefore, important to find nontoxic drugs which can be used together with TRAIL. In this study, we investigated natural compounds that can overcome resistance to TRAIL, and found that butein, a polyphenol, exhibits significant synergism with TRAIL. Treatment with TRAIL in combination with subtoxic concentrations of butein sensitizes TRAIL-resistant human leukemia U937 cells to apoptosis. Butein increased caspase-3 activity and expression of death receptor DR5. The apoptotic cell death induced by combined treatment was significantly reduced by z-DEVD-fmk, a caspase-3 inhibitor, suggesting a critical role of caspase-3 in apoptosis. These results indicate that butein sensitizes TRAIL-resistant U937 cells to TRAIL-induced apoptosis in a caspase-3 dependent manner which might be correlated with upregulation of death receptor DR5. Our data suggests that combined treatment with butein and TRAIL may provide a safe and effective strategy for treating cancer.     

Transfection of Smac/DIABLO sensitizes drug-resistant tumor cells to TRAIL or paclitaxel-induced apoptosis in vitro

Smac/DIABLO is a recently identified protein released from mitochondria in response to apoptotic stimuli and promotes apoptosis by antagonizing inhibitor of apoptosis proteins (IAPs). In this study, we observed depressed Smac/DIABLO and increased XIAP expression in ovarian epithelial tissues ordered by normal, benign and malignant epithelia. In epithelial ovarian cancer (EOC), the expression of Smac/DIABLO decreased with the malignancy. Smac/DIABLO expression showed no correlation with TRAIL sensitivity, while lower Smac/DIABLO expression and decreased release of Smac/DIABLO from mitochondria upon apoptosis stimuli were observed in paclitaxel-resistant A2780/pac cells as compared to the sensitive controls. Ectopic Smac/DIABLO alone inhibited cell growth, arrested cells in G0/G1 phase, and sensitized drug-resistant EOC cells to TRAIL or paclitaxel-induced apoptosis. Increased apoptosis was associated with the down-regulation of XIAP, FLIP, and up-regulation of Smac/DIABLO, cytochrome c, p53, along with increased activity of caspase-3. Thus, over-expression of Smac/DIABLO is a promising strategy for drug-resistant ovarian cancer treatment.     

CD59在艾滋病感染者CD4^＋T细胞表达及凋亡的影响

目的探讨补体调节蛋白CD59在艾滋病（HIV）感染者外周血CD4^＋T细胞上的表达及与凋亡之间的关系。方法收集12例确诊HIV感染者外周血标本（观察组）,同时收集10例健康对照者外周血标本（对照组）。分离外周血单个核细胞（PBMC）,并进行细胞表面染色。使用BDFACSCanto流式仪检测各项指标,采用FACSDiva软件分析CD4^＋T细胞CD59的表达情况,并分析CD59^＋CD4^＋T、CD59^-CD4^＋T细胞的凋亡情况。结果观察组CD4^＋T细胞CD59表达明显高于对照组（t=5．198,P〈0．01）;CD59＋CD4^＋细胞凋亡比率明显升高（t=5．968,P〈0．01）;而CD59^-CD4^＋T细胞的凋亡比例二组间差异无统计学意义（t=0．1353,P=0．8577）。结论HIV感染可引起CD4^＋T细胞补体调节蛋白CD59的表达,而CD59的表达会使CD4^＋T细胞凋亡增加。     

Inhibition of STAT3 expression by siRNA suppresses growth and induces apoptosis in laryngeal cancer cells

Aim: To determine the inhibitory effect of the synthetic STAT3 siRNA on the expression of STAT3 gene in human laryngeal cancer cell lines Hep2 and to investigate the effect of STAT3 siRNA on growth and apoptosis in Hep2 cells. Methods: A pair of DNA templates coding siRNA against STAT3-mRNA was synthesized to reconstruct plasmid of pSilencer1.0-U6 siRNA-STAT3. Hep2 cells were transfected with RPMI-1640 media (untreated), plasmid (empty), and STAT3 siRNA, respectively. Northern blot and Western blot analysis of STAT3 and pTyr-STAT3 expression in Hep2 cells and Western blot analysis of Bcl-2 expression in the Hep2 cell was performed 72 h after transfection. MTT, flow cytometry, and AO/EB assay were used for determination of cells proliferation and apoptosis in Hep2 cells. Results: pTyr-STAT3 was markedly expressed in untreated Hep2 cells and the vector-treated Hep2 cells, whereas pTyr-STAT3 expression was significantly reduced in STAT3 siRNA-transfected Hep2 cells, indicating that STAT3 siRNA inhibited the activity of STAT3. Transfection of Hep2 cells with STAT3 siRNA significantly inhibited STAT3 expression at both mRNA and protein level in Hep2 cells and the inhibition was characterized by time-dependent transfection. Treatment of Hep2 cells with STAT3 siRNA resulted in dose-dependent growth inhibition of Hep2, this significantly increased apoptotic cell rate, and decreased Bcl-2 expression level in Hep2 cells. STAT3 siRNA had an effect on induction of either early or late stage apoptosis. Conclusion: This study demonstrates that STAT3 siRNA effectively inhibits STAT3 gene expression in Hep2 cells leading to growth suppression and induction of apoptosis in Hep2 cells. The use of siRNA technique may provide a novel therapeutic approach to treat laryngeal cancer and other malignant tumors expressing constitutively activated STAT3.     

Inhibition of NF-kappaB by hydroquinone sensitizes human bone marrow progenitor cells to TNF-alpha-induced apoptosis

Suppression of hematopoiesis is an important mechanism governing blood cell formation. Factors such as tumor necrosis factor alpha (TNF-alpha) inhibit proliferation and colony-forming activity of bone marrow cells and activate nuclear factor kappa B (NF-kappaB) in multiple cell types. Activated NF-kappaB is required for many cells to escape apoptosis, including hematopoietic progenitor cells (HPC). The benzene metabolite hydroquinone (HQ) alters cytokine response and induces cell death in HPC, and inhibits NF-kappaB activation in T and B cells. Therefore, we studied the potential role of HQ-induced NF-kappaB inhibition in a hematopoietic cell line (TF-1) and primary HPC in rendering these cells susceptible to TNF-alpha-induced apoptosis. We demonstrate in both cell types that TNF-alpha activates NF-kappaB, and HQ exposure inhibits activation of NF-kappaB by TNF-alpha in a dose dependent manner. We further investigated the ability of HQ to potentiate TNF-alpha-induced apoptosis in these cells, and found that HQ sensitized the cells to the pro-apoptotic effect of TNF-alpha. These results suggest that NF-kappaB plays a key role in HPC survival, and that HQ-induced inhibition of NF-kappaB leaves these cells susceptible to cytokine-induced apoptosis. These effects may play a role in the suppression of hematopoiesis seen in some benzene exposed individuals.     

Oxidized low-density lipoprotein sensitizes human vascular smooth muscle cells to FAS (CD95)-mediated apoptosis

1. It was investigated in the present study whether oxidized low-density lipoprotein (oxLDL) was implicated in the susceptibility of human vascular smooth muscle cells (VSMC) to Fas-mediated death. Human fetal aorta smooth muscle cells were treated with agonistic anti-Fas antibody (CH11) and oxLDL and cell death was then determined by viability and DNA fragmentation. 2. The results of the present study show that cross-linking of Fas receptor with anti-Fas antibody in the presence of oxLDL induced death and DNA fragmentation in human VSMC, which were blocked by the caspase inhibitor z-VAD.fmk, followed by the upregulation of cell surface Fas. 3. The data indicate that oxLDL is implicated in death in VSMC and provide evidence that oxLDL is involved in Fas signal transduction. The present study proposes a novel mechanism(s) by which VSMC become susceptible to Fas ligand. 4. One of the mechanisms proposed by which oxLDL upregulates cell surface Fas is by inhibiting the degradation of Fas through the ubiquitin-proteasome pathway.     

Modulation of gene expression by siRNA in hematopoietic cells

RNA interference (RNAi) has been established as a powerful tool for identifying gene function in many biological processes and can be used for genome-wide functional genetic screens in mammalian cells. For such purposes, expression cassettes encoding RNAi triggers can be efficiently introduced into the host cell genome utilizing viral vector systems, resulting in long-term silencing of target gene expression. Transient gene silencing can also be induced by exogenous delivery of suitable RNAi triggers to target cells. However, similarly to other reverse genetic tools, there are technical challenges and limitations associated with RNAi, some of which are specific to hematopoietic cells. In this review we discuss the rational design of effective RNAi triggers, different approaches for their efficient delivery, and the value of RNAi both as a potential therapeutic strategy and as a tool for functional genomics and target validation in hematopoietic cells.     

Inhibition of VEGF expression in A431 and MDA-MB-231 tumour cells by cationic lipid-mediated siRNA delivery

In order to promote siRNA transfer in tumour cells, we used an original cationic lipid, synthesized in our laboratory, dimethyl-hydroxyethyl-aminopropane-carbamoyl-cholesterol (DMHAPC-Chol). Liposomes were prepared from this lipid and dioleoylphosphatidylethanolamine (DOPE) in equimolar proportion. Its transfecting capacity was evaluated using ELISA, cell cytometry, and RT-PCR in estimating the silencing effect of VEGF siRNA. This liposome efficiently delivered VEGF siRNA in two human cancer cell lines abundantly secreting VEGF, A431 and MDA-MB-231. Results showed that 50 nM of VEGF siRNA carried by DMHAPC-Chol/DOPE liposomes already silenced more than 90% of VEGF in these cells. A comparative study with two commercial carriers indicated that the inhibition induced by VEGF siRNA transported by cationic DMHAPC-Chol/DOPE liposomes was comparable to that induced by INTERFERin and better than lipofectamine 2000. Moreover, a transfection by a GFP plasmid followed by a GFP siRNA showed that DMHAPC-Chol/DOPE liposomes compared to lipofectamine were less efficient for plasmid but better for siRNA transport. Following one of our previous works concerning cell delivery of plasmid ( Percot et al., 2004 ), the main interest of results presented here resides in the double potential of DMHAPC-Chol/DOPE liposomes to deliver little-sized siRNA as well as large nucleic acids in cells.     

人脐静脉内皮细胞的补体攻膜复合物C5b-9模型建立

目的 建立人脐静脉内皮细胞(HUVEC)的补体攻膜复合物C5b-9模型并确定其亚溶破剂量.方法 通过体外培养HUVEC,在其表面组装攻膜复合物C5b-9,激光共聚焦检测其组装情况;增加补体浓度,通过激光共聚焦定性观察细胞上清液中乳酸脱氢酶(LDH)活性定量检测,确定其亚溶破剂量.结果 激光共聚焦结果显示C5b-9成功组装于HUVEC表面;当C5b6的浓度达到1.6 mg·L-1时,LDH的分泌量骤增,激光共聚焦显示该剂量下部分细胞胞膜破裂.结论 成功建立人脐静脉内皮细胞的补体攻膜复合物C5b-9模型,为研究动脉粥样硬化药物防治奠定基础.     

Inhibition of tumor cell growth in vitro by 2-mercaptoethanesulfonate (mesna) and other thiols

2-Mercaptoethanesulfonate (Mesna), which is used as a uroprotective agent during oxazaphosphorine treatment, was previously found to inhibit growth of several tumor cell lines in vitro. To test the possibility that this effect is due to the SH-group of mesna, other thiols have now been tested. It has been observed that L-cysteine, N-acetyl-L-cysteine and glutathione, on a molar basis, had effects similar to mesna on [3H]thymidine incorporations of several human tumor cell lines in vitro. The dose-response profiles were monophasic for some cell lines and biphasic for others. It is suggested that compounds with SH-groups, in relatively high concentrations, may be toxic for cells.     

siRNA抑制人乳腺癌SK-BR-3细胞株VEGF基因表达的实验研究

目的研究siRNA(small interfering,RNA)对乳腺癌细胞SK-BR-3的VEGF基因表达的抑制作用,为RNAi技术在肿瘤生物治疗中的应用提供实验基础。方法体外合成一条针对VEGF基因的siRNA,使用脂质体转染的方法导入细胞,观察转染后乳腺癌细胞SK-BR-3的增殖变化,MTT法检测细胞存活率,RT-PCR检测转染后VEGFmRNA表达水平的变化,ELISA检测蛋白表达的下降效果。结果所设计的siRNA能有效抑制乳腺癌细胞的生长;降低了VEGFmRNA的表达;蛋白表达水平也显著降低。作为阴性对照的错义序列组siRNA则没有这种效果,不起作用。结论 siRNA可以有效抑制细胞株SK-BR-3中VEGF的表达,从而抑制细胞生长。应用RNA干扰技术可以有效抑制肿瘤细胞的增殖。     

The p55 tumor necrosis factor receptor (CD120a) induces endothelin-1 synthesis in endothelial and epithelial cells

Synthesis of the vasoconstrictor peptide endothelin-1 by endothelial and epithelial cells is strongly induced by tumor necrosis factor alpha (TNF-alpha). The actions of TNF-alpha are mediated by two transmembrane receptors of approximately 55 (p55, CD120a) and 75 kDa (p75, CD120b). Reagents activating selectively these receptor subtypes have been used to identify which TNF receptor mediates the induction of endothelin-1 synthesis. Stimulation of bovine aortic endothelial cells or human HEp-2 epithelial cells with a p55-selective mutant of human TNF-alpha (R32W-S86T) induced significant and concentration-dependent increases in endothelin-1 release. A p75 receptor-selective TNF-alpha mutant (D143N-A145R) was ineffective alone or in combination with the p55-selective mutant. Competitive binding experiments with [125I]TNF-alpha showed the p55-selective mutant, but not the p75-selective mutant, to inhibit the binding of [125I]TNF-alpha to endothelial and HEp-2 cells. Similar results were obtained with the p55 agonist antibody htr1 in both cell lines. These results establish the p55 TNF receptor as the main receptor involved in the induction of endothelin-1 synthesis by TNF-alpha.     

Dicer-substrate siRNA inhibits tumor necrosis factor alpha secretion in Kupffer cells in vitro: in vivo targeting of Kupffer cells by siRNA-liposomes

Tumor necrosis factor alpha (TNF-α) plays a major role in the pathogenesis of many inflammatory diseases. Neutralizing TNF-α by antibodies or antisense oligodeoxynucleotides, alleviate disease symptoms. In this study, we introduce the new generation of gene-silencing molecules, namely the small interfering RNAs (siRNAs) to reduce TNF-α. Although siRNAs of 19-21bp are commonly used, it is reported that longer siRNAs have much higher efficacies. Here, we report the identification of a 27-mer Dicer-substrate siRNA (DsiRNA) against TNF-α mRNA. Primary cells of rat Kupffer cells were transfected with five 27-mer siRNA constructs (si27-1, si27-2 si27-3, si27-4 and si27-5) for 24h, following which, TNF-α secretion was induced by exposure to LPS (0.1μg/ml) for 2h. TNF-α released to the medium was measured by ELISA. Of the five si27 constructs, si27-3 had the highest inhibitory effect on TNF-α secretion. At 10nM, si27-3 inhibited TNF-α secretion by 80% compared to a 60% inhibition by a 21-mer (SSL3). Following encapsulation in anionic liposomes, si27-3 at 100μg/kg body weight, on two successive days by intravenous administration, inhibited the secretion of TNF-α by 50%. These data demonstrate the identification of a highly efficacious siRNA formulation, which can be used in the treatment of TNF-α mediated diseases.     

青蒿琥酯钠对体外大鼠红细胞膜钠-钾交换ATP酶的抑制

体外测定青蒿琥酯钠(SA)对大鼠红细胞膜Na~( )-K~( )-交换ATP酶活性的影响.方法:在反应系统中分别加入不同浓度的SA(0,0.5,1,5和10 μmol·L~(-1)),通过测定反应系统中释放的无机磷含量,计算酶活性.结果:随着SA浓度(O,0.5,1,5和10 μmol·L~(-1))的增高,对Na~( )-K~( )-交换ATP酶活性的抑制作用也随之增强,抑制率分别为15％,29％,46％和75％.将底物ATP浓度增加为125,250,375和500 μmol·L~(-1),进行了酶的动力学测定.用直线回归分析作Eadie-Hofstee动力学曲线,结果表明,SA对该酶的抑制作用为竞争性抑制.结论:提示SA可影响宿主红细胞膜的离子转运及膜的功能.     

Methylseleninic acid, a potent growth inhibitor of synchronized mouse mammary epithelial tumor cells in vitro

Selenium compounds have been shown to be effective chemopreventive agents in several animal models and in cultured cells in vitro. It has been proposed that compounds able to generate monomethyl Se have an increased potential to inhibit cell growth. To test this hypothesis, methylseleninic acid (MSeA) and other compounds that could generate methylselenol rapidly were compared with Se compounds that do not generate monomethyl Se, using a well-characterized synchronized TM6 mouse mammary epithelial tumor model in vitro. MSeA at a low micromolar concentration inhibited TM6 growth after 10- to 15-min treatment times. Cells resumed growth after 24 hr but remained sensitive to the fresh addition of monomethyl Se-generators. Dimethyl selenide (DMSe), a putative metabolite of methylselenol, was inactive. Cells treated with 5 microM MSeA were arrested in G1. The effects of 5 microM MSeA on gene expression were evaluated using the Atlas mouse cDNA expression array. A 10-min exposure with MSeA caused a 2- to 3-fold change in the expression of three genes: laminin receptor 1 (decreased), integrin beta (decreased), and Egr-1 (increased). The results provide experimental support for the hypothesis that monomethylated forms of Se are the critical effector molecules in Se-mediated growth inhibition in vitro.