细胞外信号调节激酶1/2参与三氧化二砷诱导的胶质瘤细胞凋亡

目的:探讨细胞外信号调节激酶1/2(ERK1/2)信号通路在三氧化二砷诱导的胶质瘤细胞U251凋亡中的作用,为应用三氧化二砷治疗胶质瘤奠定基础。方法:50μmol/L三氧化二砷作用U251细胞,不同时间检测胶质瘤细胞增殖活性,半定量PCR检测ERK1/2mRNA表达,Western blot检测ERK1/2蛋白表达;Ho-echst33258染色及流式细胞术(FCM)检测细胞凋亡;转染ERK1/2上游激酶MEK1,应用ERK1/2激酶抑制剂U0126观察ERK1/2通路在肿瘤凋亡及增殖中的作用;比色分析法检测Caspase-3活性的变化。结果:三氧化二砷诱导胶质瘤细胞发生明显凋亡,抑制肿瘤细胞增殖;增加ERK1/2蛋白的表达,呈时间依赖性;阻断ERK1/2信号通路后胶质瘤细胞凋亡受到抑制,Caspase-3活性下降。结论:ERK1/2信号通路在三氧化二砷诱导的胶质瘤细胞凋亡中起重要作用。     

Netrin-4对胶质母细胞瘤细胞ERK/MAPK信号通路的影响

目的:通过免疫印迹方法检测不同浓度的Netrin-4(NTN4)重组蛋白对GBM细胞中磷酸化ERK水平的影响,初步探讨NTN4对GBM细胞ERK/MAPK信号通路的调控作用.方法:体外培养野生型GBM细胞:U251 MG细胞及U87MG细胞,加入两种不同浓度的NTN4重组蛋白(5ng/ml,50ng/ml),裂解细胞提取目的蛋白,在不同时间点(0,10min/20min,30min,1h,2h,3h)通过免疫印迹方法检测磷酸化ERK水平变化情况.结果:加入NTN4后,U251 MG细胞和U87MG细胞中的磷酸化ERK水平都有所增加;在U251 MG细胞中,5ng/ml的NTN4作用后1h,磷酸化ERK水平最高,50ng/ml的NTN4作用后10分钟,磷酸化ERK水平最高;在U87MG细胞中,不同浓度的NTN4都在作用10分钟时,磷酸化ERK水平最高.结论:Netrin-4激活胶质母细胞瘤细胞内ERK/MAPK信号通路,是其抑制GBM细胞衰老的可能机制.     

沉默BRG1基因对人胶质瘤细胞增殖的影响及其机制北大核心CSCD

目的探讨小干扰RNA(siRNA)沉默胶质瘤细胞BRG1基因表达对其增殖的影响及其机制。方法化学合成BRG1 siRNA,脂质体介导转染胶质瘤U251和U87细胞。CCK-8细胞增殖实验检测细胞增殖,流式细胞仪分析细胞周期变化,Western blot检测BRG1、cyclin家族、CDK抑制剂蛋白表达水平。结果转染BRG1 siRNA可以有效减少胶质瘤U251和U87细胞BRG1表达,细胞增殖下降,G1期细胞增加。BRG1沉默后cyclin D1和cyclin B1表达降低,CDK抑制剂p21和p27没有明显变化。结论沉默胶质瘤细胞BRG1表达影响细胞周期蛋白使细胞停滞在G1期,最终抑制胶质瘤细胞增殖。     

RNA干扰细胞黏附分子L1表达逆转胶质瘤U251细胞多药耐药

背景与目的：细胞黏附分子L1（cell adhesionmoleculeL1,L1CAM）是一种跨膜黏附蛋白,在神经系统发育及肿瘤发生中发挥重要作用。本研究运用RNA干扰（RNAinterference,RNAi）技术抑制L1CAM表达,并探讨其对胶质瘤U251细胞多药耐药的逆转作用及相关分子机制。方法：将针对L1CAM的小干扰RNA（siLl）和阴性对照siRNAfsiCon）转染人胶质瘤U251细胞。实验分3组：空白对照组（胶质瘤U251细胞）、阴性对照组（转染siCon的胶质瘤U251细胞）、实验组f转染siLl的胶质瘤U251细胞）。蛋白质印迹法（Westernblotting）~U251细胞中L1CAM、MRPl、pAKT及pERK1／2等蛋白表达。细胞增殖实验检测L1CAM对顺铂（cisplatin）和P13K／AKT抑制剂LY294002抑制U251细胞增殖的影响。免疫荧光染色法检测抑制LICAM表达对U251细胞系中AKT磷酸化情况的影响。结果：实验组L1CAM、pAKT．pERKl／2蛋白表达量明显低于阴性对照组和空白对照组（P〈0．01）,但实验组多药耐药蛋白MRPl表达量以及Bcl-2cdBax与阴性对照组和空白对照组相比无明显变化。实验组顺铂和LY294002对U251细胞增殖的抑制率高于阴性对照组和空白对照组,提示抑制LICAM表达后细胞对顺铂和LY294002的敏感性增加。免疫荧光结果显示,与阴性对照组和空白对照组相比,实验组细胞内AKT磷酸化信号明显降低。结论：RNAi抑制L1CAM表达能增强顺铂和LY294002对U251细胞增殖的抑制作用,并可抑制P13K／AKT和MAPK信号激活．一定程度上可逆转胶质瘤细胞的多药耐药性。     

miR-7沉默EGFR/PI3K通路逆转脑胶质瘤U251细胞的恶性表型

目的:探讨利用微RNA(microRNA-7,miR-7)靶向沉默表皮生长因子受体(epidermal growth factor receptor,EGFR)/磷脂酰肌醇3激酶(phosphatidylinositol kinase-3,PI3K)通路途径逆转脑胶质瘤的恶性表型。方法:利用脂质体转染法将带有miR-7基因序列的表达质粒转入人脑胶质瘤细胞株U251中;采用实时荧光定量-PCR(real-time fluorogenic quantitative-PCR,RFQ-PCR)方法检测转染细胞中miR-7的表达水平;免疫细胞化学法和蛋白质印迹法检测EGFR、PI3K和AKT2蛋白的表达情况;绘制细胞生长曲线,FCM法检测细胞周期变化,Transwell小室法检测瘤细胞迁移能力,软琼脂克隆形成实验检测肿瘤细胞致瘤性。结果:RFQ-PCR结果显示,miR-7基因转染组细胞中miR-7水平明显高于对照组和无义序列组;蛋白质印迹法检测结果显示,转染组U251细胞中EGFR、PI3K和AKT2蛋白的水平较对照组均有明显降低(P<0.05);U251细胞增殖速度减慢,处于S期的细胞所占比例减少,细胞迁移及软琼脂克隆形成能力均有明显降低(P<0.05)。结论:转染miR-7可有效沉默胶质瘤U251细胞中EGFR/PI3K通路主要成员蛋白的表达,进而逆转其恶性表型,有望成为一种新的胶质瘤基因治疗方法。     

顺铂耐受胶质瘤细胞株诱导和细胞自噬的观察

背景与目的:明确胶质瘤耐药相关分子机制,有助于寻找新的治疗对策。我们将诱导对顺铂耐药的脑胶质瘤细胞株,探讨细胞自噬和胶质瘤细胞顺铂耐受的关系。方法:应用人胶质瘤细胞株U251,采用顺铂剂量梯度爬升筛选方法,诱导耐药胶质瘤细胞株;用MTT法测定该耐药细胞对顺铂的半数抑制浓度(IC50);电镜和GFP-LC3荧光染色检测细胞内自噬体;AnnexinV-FITC染色检测细胞凋亡;Western blot检测自噬相关蛋白LC3、Beclin1以及凋亡分子Caspase-3水平。结果:我们诱导获得的耐药胶质瘤细胞株U251/CP2对顺铂半数抑制浓度(IC50)较亲代U251增加了62.7倍(分别是1.2±0.4μg/ml和76.5±22.5μg/ml)。电镜和GFP-LC3荧光染色观察表明胶质瘤细胞呈现典型的自噬特征,表现为电镜下广泛的自噬性空泡的出现和GFP-LC3斑点状分布,且能够被自噬抑制剂3-MA和ERK抑制剂PD98059抑制。凋亡检测表明,经顺铂处理后,U251/CP2较U251凋亡率低,3-MA和PD98059能够显著增强顺铂对U251/CP2的凋亡诱导作用。Western blot检测表明,U251/CP2较U251具有显著上调的LC3和Beclin1水平,而Caspase-3水平较低。结论:U251胶质瘤细胞能够通过自噬作用保护细胞免受化疗药物顺铂的杀伤,从而免于发生细胞凋亡。     

Galectin-3调控Wnt信号通路对脑胶质瘤细胞凋亡的影响

目的:半乳糖凝集素-3（Galectin-3）调控Wnt信号通路对人脑胶质瘤细胞凋亡的影响。方法:RT-PCR及Western blot检测人脑胶质瘤组织中Galectin-3的mRNA和蛋白表达;Western blot检测人脑胶质瘤U251、U87、SHG-44细胞中Galectin-3的蛋白表达;将Galectin-3的特异性siRNA(Galectin-siRNA)转染人脑胶质瘤U87细胞,Western blot、流式细胞术分别检测转染48 h后Galectin-3、Wnt5a、β-catenin和Cleaved caspase3蛋白表达及细胞凋亡率。结果:Galectin-3在人脑胶质瘤组织mRNA和蛋白表达均显著高于瘤旁组织（P＜0.01）;U251、U87、SHG-44细胞中Galectin-3蛋白表达从高到低为U87>U251>SHG-44,选择U87细胞作为后续研究;Galectin-3-siRNA1的Galectin-3蛋白表达最低,选择作为后续研究;NC-siRNA组细胞凋亡率、Cleaved caspase3、Wnt5a、β-catenin蛋白表达与对照组差异不显著（P＞0.05）,与对照组比较,Galectin-3-siRNA组细胞凋亡率明显升高,Cleaved caspase3蛋白表达明显升高,Wnt5a和β-catenin蛋白表达明显降低（P＜0.01）。结论:沉默Galectin-3表达可诱导人脑胶质瘤细胞凋亡,机制可能与Wnt信号通路的下调有关。     

褪黑素通过下调HIF-1α表达增强卵巢癌细胞OVCAR3顺铂敏感性

目的:探讨褪黑素对卵巢癌细胞顺铂敏感性的影响及其机制。方法:采用不同浓度褪黑素联合顺铂作用于卵巢癌细胞OVCAR3,MTT法检测细胞增殖,流式细胞术检测细胞凋亡,Western blot检测凋亡相关蛋白及信号通路蛋白AKT及ERK的磷酸化,同时检测褪黑素对HIF-1α蛋白表达的影响。结果:MTT结果显示,褪黑素和顺铂联合作用能够显著抑制OVCAR3细胞增殖(P<0.05)。流式细胞仪检测结果显示,褪黑素和顺铂联合作用相较于单独顺铂作用或褪黑素作用能够显著增加OVCAR3细胞的凋亡。Western blot结果显示,褪黑素与顺铂联合作用能够增加促凋亡蛋白BAX及Caspase3的表达,抑制抗凋亡蛋白BCL2的表达,检测信号通路结果显示,褪黑素与顺铂联合作用能够促进AKT及ERK的磷酸化,同时褪黑素能够抑制HIF-1α蛋白的表达。结论:褪黑素通过抑制HIF-1α的表达使OVCAR3细胞对顺铂敏感。     

PDCD4基因在胶质瘤细胞系的稳定表达及其对肿瘤细胞生长的影响

目的:建立稳定表达程序性死亡4基因(programmed cell death 4, PDCD4)的人神经胶质瘤U251细胞系,观察PDCD4基因对人神经胶质瘤细胞增殖及细胞周期的影响.方法:将构建好的携带PDCD4重组真核表达载体pEGFP-PDCD4转染U251细胞,经过G418筛选获得稳定细胞系;用RT-PCR及Western blotting检测PDCD4 mRNA和蛋白的表达情况,通过锥虫蓝染色活细胞计数法及克隆形成实验检测外源PDCD4转染对细胞增殖和克隆形成能力的影响,以流式细胞术检测细胞周期.结果:成功建立稳定表达PDCD4的胶质瘤细胞U251-PDCD4.未转染的U251及空载体转染的U251细胞均不表达PDCD4,而pEGFP-PDCD4转染的U251-PDCD4细胞表达高水平的PDCD4 mRNA和蛋白质;转染PDCD4基因的细胞生长速度明显减慢(P<0.01)、克隆形成率明显降低(P<0.01);细胞周期检测显示,转染PDCD4的细胞较其他两对照组细胞S期升高、G2/M期明显降低(P<0.05).结论:PDCD4通过干扰细胞周期明显抑制胶质瘤U251细胞的细胞增殖及克隆形成能力.     

乙型肝炎病毒X蛋白对人肝癌细胞hsp90α基因表达调控机制研究

目的:探讨乙型肝炎病毒X蛋白(hepatitis B virus X protein,HBx)参与人肝癌细胞hsp90α基因表达的调控机制。方法:采用半定量RT-PCR、蛋白质印迹法及荧光素酶活性检测技术,检测不同剂量HBx表达载体转染的HepG2细胞中hsp90α基因mRNA和蛋白表达及启动子活性的变化,并观察转录因子c-Myc阻断剂10058-F4对上述效应的影响。采用启动子实验分析c-Myc对hsp90α基因启动子的激活作用。RT-PCR和蛋白质印迹法检测表达HBx的HepG2细胞中c-Myc mRNA和蛋白表达情况;蛋白质印迹法及ELISA分析细胞外信号调节激酶1/2(ERK1/2)和磷酸化ERK1/2(p-ERK1/2)表达水平及内源性ERK的活性。结果:HBx基因转染HepG2细胞中hsp90α基因的mRNA和蛋白表达水平以及启动子活性呈剂量-依赖性增强,P=0.006 1;c-Myc阻断剂抑制了HBx对hsp90α基因表达的上调效应。c-Myc通过与c-Myc位点(-1094/-1088)结合转录激活hsp90α基因启动子活性。HBx使HepG2细胞中c-Myc mRNA和蛋白表达增强,并伴有ERK1/2蛋白磷酸化水平增加,ERK活性明显提高,P=0.032。结论:HBx通过ERK信号通路反式激活肝癌细胞c-Myc介导的hsp90α基因启动子活性,从而上调hsp90α基因表达。     

Downregulation of Smac/DIABLO expression in renal cell carcinoma and its prognostic significance.

PURPOSE: Second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI (Smac/DIABLO) was recently identified as a protein that is released from mitochondria in response to apoptotic stimuli and promotes apoptosis by antagonizing inhibitor of apoptosis proteins. Furthermore, Smac/DIABLO plays an important regulatory role in the sensitization of cancer cells to both immune- and drug-induced apoptosis. However, little is known about the clinical significance of Smac/DIABLO in various cancers, including renal cell carcinoma (RCC). This study examined Smac/DIABLO expression in 78 healthy kidneys and 78 RCCs. MATERIALS AND METHODS: The level of Smac/DIABLO expression was quantified by Western blot analysis using nonfixed fresh frozen tissues. RESULTS: The expression of Smac/DIABLO was lower in RCC compared with the autologous normal kidney. Sixty-four (82%) of 78 of RCC expressed Smac/DIABLO, and 18% were negative, whereas 100% of normal kidney tissues were positive. In stage I/II RCC, 96% expressed Smac/DIABLO, whereas only 50% expressed Smac/DIABLO in stage III/IV. Smac/DIABLO expression inversely correlated with the grade of RCC. Patients with RCC expressing Smac/DIABLO had a longer postoperative disease-specific survival than those without Smac/DIABLO expression in the 5-year follow-up. Transfection with Smac/DIABLO cDNA enhanced tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) -mediated and cisplatin-mediated cytotoxicity in RCC. CONCLUSION: The present study demonstrates for the first time that Smac/DIABLO expression was downregulated in RCC and that no Smac/DIABLO expression in RCC predicted a worse prognosis. In addition, transfection with Smac/DIABLO sensitized RCC to TRAIL/cisplatin-induced apoptosis. These results suggest that Smac/DIABLO expression in RCC may be used as a prognostic parameter, and that enhancement of Smac/DIABLO expression in RCC may potentiate immunotherapy and chemotherapy.     

survivin反义脱氧寡核苷酸对胃癌细胞增殖与凋亡的影响

目的 探讨survivin反义脱氧寡核苷酸(ASODN)对胃癌细胞株BGC-823凋亡、增殖的作用及分子机制.方法 分别以survivin ASODN-1、survivin ASODN-2和survivin ASODN-3转染人胃癌BGC-823细胞株,采用共聚焦显微镜检测转染率,四甲基偶氮唑蓝(MTF)法检测细胞生长活性,流式细胞术检测细胞凋亡指数、增殖指数和细胞周期分布及survivin、血管内皮生长因子(VEGF)、Smac/DIABLO蛋白表达改变,逆转录聚合酶链反应检测survivin、VEGF、Smac/DIABLO mRNA表达改变.结果 转染各序列survivin ASODN均可下调survivin蛋白的表达,且以ASODN-2作用最为显著.以600 nmol/L survivin ASODN-2转染BGC-823细胞48 h后,G0/G1期细胞比例[(72.25±2.95)%]明显高于空脂质体对照组[(56.25±0.75)%,均P＜0.05],凋亡指数[(11.31±0.38)%]明显高于空脂质体对照组[(1.62±0.36)%,均P＜0.05],增殖指数[(27.77±2.97)%]低于空脂质体对照组[(43.80±0.80)%,均P＜0.05].转染后survivin mRNA及蛋白表达(0.523±0.091,0.733±0.009)低于空脂质体对照组(0.861±0.047,0.997±0.233;均P＜0.05),VEGF mRNA及蛋白表达(0.519±0.076,0.75±0.006)低于空脂质体对照组(0.779±0.059,1.000±0.01;均P＜0.05),Smac/DIABLOmRNA及蛋白表达(0.899±0.113,1.637±0.023)高于空脂质体对照组(0.558±0.041,1.000±0.049;均P＜0.05).结论 survivin ASODN具有诱导胃癌细胞凋亡、抑制细胞增殖的作用,其作用是通过下调survivin和VEGF、上调Smac/DIABLO基因表达实现的.

Abstract：

Objective To explore the effects of antisense oligodeoxynucleotides (ASODN)on proliferation and apoptosis in gastric cancer cell line BGC-823 cells and the molecular mechanisms induced by ASODN.Methods survivin ASODN-1, survivin ASODN-2 and survivin ASODN-3 were transfected into BGC-823 cells by LipofectamineTM 2000 transfection reagent.The growth activity of BGC-823 cells was detected by MTT assay.Apoptosis index (AI), proliferation index ( PI), cell cycle and expressions of survivin, VEGF and Smac/DIABLO proteins were detected by flow cytometry (FCM).The changes of survivin mRNA, VEGF mRNA and Smac/DIABLO mRNA were detected by RT-PCR.Results The expression of survivin was down-regulated by the three ASODN sequences, especially the ASODN-2 was best.At 48 hours after transfection with 600 nmol/L survivin ASODN-2, the cells in G1/G0 phase were significantly increased [(72.25 ± 2.95 ) %], apoptotic index increased [( 11.31 ± 0.38 ) %], proliferation index decreased [(27.77 ± 2.97 ) %], compared with those in the control group [( 56.25 ± 0.75 ) %,(1.62 ±0.36)%, (43.80 ±0.80)%, all P ＜ 0.05].The survivin mRNA and protein levels (0.523 ±0.091,0.733 ±0.009) were down-regulated compared with those in the control group (0.861 ±0.047,0.997 ± 0.233 ), VEGF (0.519 ± 0.076, 0.75 ± 0.006) were down-regulated compared with those in the control group (0.779 ± 0.059, 1.000 ± 0.01 ), while those of Smac/DIABLO (0.899 ± 0.113, 1.637 ±0.023) were up-regulated compared with those in the control group (0.558 ± 0.041, 1.000 ± 0.049, all P＜0.05).Conclusions Survivin ASODN can induce apoptosis and inhibit the proliferation of gastric cancer cell line BGC-823 cells.Those effects are induced through up-regulation of Smac/DIABLO and downregulation of survivin and VEGF expression simultaneously.     

Disturbed balance of expression between XIAP and Smac/DIABLO during tumour progression in renal cell carcinomas

Dysregulation of apoptosis plays an important role in tumour progression and resistance to chemotherapy. The X-linked inhibitor of apoptosis (XIAP) is considered to be the most potent caspase inhibitor of all known inhibitor of apoptosis-family members. Only recently, an antagonist of XIAP has been identified, termed Smac/DIABLO. To explore the relevance of antiapoptotic XIAP and proapoptotic Smac/DIABLO for tumour progression in renal cell carcinomas (RCCs), we analysed XIAP and Smac/DIABLO mRNA and protein expression in the primary tumour tissue from 66 RCCs of all major histological types by quantitative real-time PCR, Western blot and ELISA. X-linked inhibitor of apoptosis and Smac/DIABLO mRNA expression was found in all RCCs. Importantly, the relative XIAP mRNA expression levels significantly increased from early (pT1) to advanced (pT3) tumour stages (P=0.0002) and also with tumour dedifferentiation (P=0.04). Western blot analysis confirmed the tumour stage-dependent increase of XIAP expression on the protein level. In contrast, mRNA and protein expression levels of Smac/DIABLO did not significantly change between early and advanced tumour stages or between low and high tumour grades. Consequently, the mRNA expression ratio between antiapoptotic XIAP and proapoptotic Smac/DIABLO markedly increased during progression from early (pT1) to advanced (pT3) tumour stages. Moreover, RCCs confined within the organ capsule (pT1 and pT2) exhibited a significantly lower XIAP to Smac/DIABLO expression ratio when compared with RCCs infiltrating beyond the kidney (pT3; P=0.01). Thus, our investigation demonstrates that the delicate balance between XIAP and Smac/DIABLO expression is gradually disturbed during progression of RCCs, resulting in a relative increase of antiapoptotic XIAP over proapoptotic Smac/DIABLO, thereby probably contributing to the marked apoptosis resistance of RCC.     

凋亡相关基因Livin、Smac／DIABLO在胃癌组织中的表达及其意义

背景与目的：作为一种促凋亡基因,Smac／DIABLO与凋亡抑制基因Livin相互作用,共同参与调控细胞癌变的起始及发展。本研究检测凋亡抑制蛋白Livin及线粒体促凋亡蛋白Smac／DIABLO在胃癌组织中的表达．观察其表达水平与胃癌各临床病理因素的关系。方法：应用实时荧光定量PCR SYBR Green荧光染料法检测75例手术切除的胃癌组织、20例癌旁组织及正常胃组织中Livin mRNA和Smac／DIABLO mRNA的表达,Westernblot结合及免疫组化SP法检测两种蛋白的表达及组织学定位。结果：正常胃组织及癌旁组织中均无Livin mRNA表达,胃癌组织中Livin mRNA表达显著上调,相对表达量为6．374±4．759,低分化胃腺癌组织及有淋巴结转移组的相对表达量显著高于中高分化胃腺癌组织（P〈0．05）,其表达与肿瘤大小、浸润深度及TNM分期无关,Livin蛋白的表达结果与之相符;胃癌组织中Smac／DIABLO mRNA的表达（0．731±0．420）低于正常胃组织（1．104±0．276）及癌旁组织（1．061±0．737）,但差异无统计学意义（P〉0．05）,Smac／DIABLO mRNA表达水平与胃癌各临床病理因素无关;Smac／DIABLO蛋白表达与mRNA表达存在差异。Smac／DIABLO在肠型胃癌（84．38％）与弥漫型胃癌（60．65％）中的表达有一定差异（P〈0．05）。结论：Livin与Smac／DIABLO在不同阶段和不同病理类型胃癌中的表达及相关性存在差异,Livin基因高表达与胃癌的发生及分化转移密切相关。     

Smac/DIABLO增强子宫内膜癌细胞对紫杉醇化疗敏感性的机制研究

目的:研究上调Smac/DIABLO基因在人子宫内膜癌Ishikawa细胞中的表达,对紫杉醇化疗增敏方面的作用及可能机制。方法:构建Smac/DIABLO的过表达质粒pcDNA3.1-Smac,应用脂质体法转染人子宫内膜癌Ishikawa细胞,实验分为过表达组、空载体对照组和空白对照组。转染48 h后,应用qRT-PCR和Western blot法检测Smac/DIABLO mRNA及蛋白表达情况。将转染pcDNA3.1-Smac的Ishikawa细胞暴露于终浓度为0.1 μmol/L紫杉醇中,实验分为pcDNA3.1-Smac+紫杉醇组、紫杉醇组和空白对照组,CCK-8法检测暴露紫杉醇24,48,72,96 h,3组细胞增殖能力的变化。应用Western blot检测Ishikawa细胞过表达Smac/DIABLO并暴露于紫杉醇后,Caspase-3,Caspase-7,Caspase-9蛋白的表达情况。结果:转染48 h后,过表达组较空载体对照组、空白对照组,Smac/DIABLO mRNA及蛋白相对表达量均明显增加（F=152.056,P=0.002;F=697.953,P=0.001）。CCK-8实验结果显示,过表达Smac/DIABLO并暴露于紫杉醇后,pcDNA3.1-Smac+紫杉醇组较紫杉醇组和空白对照组,细胞增殖能力受到抑制（P＜0.05）。Western blot检测到pcDNA3.1-Smac+紫杉醇组Caspase-3,Caspase-7,Caspase-9蛋白的相对表达量比较另外两组明显增加（FCaspase-3=434.277,FCaspase-7=392.401,FCaspase-9=88.936,P＜0.05）。结论:上调Smac/DIABLO表达可增强Ishikawa细胞对紫杉醇的化疗敏感性,其机制可能通过线粒体和死亡受体两条途径,解除凋亡抑制蛋白家族对Caspase的抑制作用。     

Role of Smac/DIABLO in cancer progression

Second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI (Smac/DIABLO) is a proapoptogenic mitochondrial protein that is released to the cytosol in response to diverse apoptotic stimuli, including commonly used chemotherapeutic drugs. In the cytosol, Smac/DIABLO interacts and antagonizes inhibitors of apoptosis proteins (IAPs), thus allowing the activation of caspases and apoptosis. This activity has prompted the synthesis of peptidomimetics that could potentially be used in cancer therapy. For these reasons, several authors have analyzed the expression levels of Smac/DIABLO in samples of patients from different tumors. Although dissimilar results have been found, a tissue-specific role of this protein emerges from the data. The objective of this review is to present the current knowledge of the Smac/DIABLO role in cancer and its possible use as a marker or therapeutic target for drug design.     

Low circulating serum levels of second mitochondria-derived activator of caspase (Smac/DIABLO) in patients with bladder cancer

Smac/DIABLO promotes apoptosis by antagonizing inhibitor of apoptosis proteins. The expression of Smac/DIABLO in tissues has been reported in various cancers; however, little is known about circulating levels of Smac/DIABLO. The present study was designed to first determine if Smac/DIABLO can be detected in the serum and then assess whether the circulating levels of Smac/DIABLO are of prognostic significance in patients with bladder cancer. The levels of Smac/DIABLO in the sera of 173 patients with bladder cancer and 36 normal donors were determined by using an enzyme-linked immunosorbent assay. The mean serum level of Smac/DIABLO in patients with bladder cancer was approximately 2-fold lower than that in normal donors. The mean level of serum Smac/DIABLO in patients with muscle-invasive bladder cancer was lower than that in patients with non-muscle invasive cancer. In addition, the mean serum Smac/DIABLO level in patients with T4 muscle-invasive bladder cancer was lower than that in patients with T2 and T3 cancers. The mean serum level of Smac/DIABLO in patients with Grade 3 bladder cancer was lower than that in patients with Grade 1 and Grade 2 cancers. Analysis by Kaplan-Meier revealed that patients with Ta and T1 non-muscle invasive bladder cancer with high level of serum Smac/DIABLO (more than mean value) had a longer post-operative tumor-free interval than those with low level (less than mean value) in the 3-year follow-up. Furthermore, patients with T2-T4 muscle-invasive bladder cancer with high serum Smac/DIABLO level (more than mean value) had a higher post-operative disease-free rate when compared with patients with low level (less than mean value) in the 5-year follow-up. The present study is the first to analyze circulating levels of Smac/DIABLO in the serum. The findings demonstrate that the mean serum level of Smac/DIABLO was downregulated in patients with bladder cancer compared to control healthy individuals, especially high grade muscle-invasive bladder cancer. Noteworthy, lower serum level of Smac/DIABLO predicted early recurrence in patients with bladder cancer. Overall, the findings suggest that measuring the levels of Smac/DIABLO in the serum may be considered a prognostic parameter in patients with bladder cancer. Furthermore, Smac/DIABLO may be a molecular therapeutic target in bladder cancer.     

CD56 and CD11b Positivity with Low Smac/DIABLO Expression as Predictors of Chemoresistance in Acute Myeloid Leukaemia: Flow Cytometric Analysis

Background: Resistance to chemotherapy is a major obstacle to curing acute myeloid leukaemia (AML), andseveral antigens are claimed to play primary roles in this resistance. Purpose: The aim of this study was to evaluatethe roles of CD56, CD11b and Smac/DIABLO gene expression levels as prognostic markers of the clinical outcome,response to chemotherapy and survival of AML patients. Materials and Methods: A cross-sectional observationalstudy was conducted on 60 naïve-AML patients who received induction therapy with mitoxantrone and cytarabinecombined with a high dose of cytarabine. The CD56,CD11b and Smac/DIABLO expression levels were assessed usingflow cytometry at diagnosis and were analysed for correlation with the possible associated risk factors, response tochemotherapy, and median duration of disease-free survival (DFS) and overall survival (OS). Results: The overall resultsrevealed that AML patients who exhibited positive expression for CD56 and CD11b had short median durations of DFSand OS.(P = 0.019, 0.006, 0.029 and 0.024, respectively). Additionally, low Smac/DIABLO expression had a negativeimpact on treatment outcome in terms of CR rate (p=0.012) and reduced DFS (p=0.000) and OS(p=0.000) values.Conclusions: CD56 and CD11b positivity and low Smac/DIABLO expression are important predictive factors forthe occurrence of chemoresistance, in addition to other risk factors, among AML patients.     

Synthetic Smac peptide enhances the effect of etoposide-induced apoptosis in human glioblastoma cell lines

Summary Smac/DIABLO is a mitochondrial protein released into cytosol during the progression of apoptosis. Smac/DIABLO promotes apoptosis by neutralizing the inhibitory effect of the inhibitor of apoptosis proteins (IAPs) on the processing and activity of the effecter of caspase. Here, we generated synthetic Smac peptide which possesses an IAP-binding domain and Drosophila antennapaedia penetration sequence, and examined whether it enhances the effect of the chemotherapeutic agent etoposide in the human glioblastoma cell line. Cellular uptake of Smac peptide in several glioma cell lines was most prominent at 6–12 h after addition. Caspase activity assay showed that our peptide successfully increased the activity of caspase-3 and caspase-9 in etoposide-induced apoptosis. In addition, Smac peptide increased the amount of cleaved PARP (poly ADP-ribose polymerase), but control peptides did not. Moreover, the addition of z-VAD-fmk, a caspase inhibitor, counterbalanced the effect of Smac peptide. Finally, we demonstrated that Smac peptide could enhance the growth inhibition effect of etoposide compared with control peptides. These results suggest that synthetic Smac peptide may be a new molecular targeting anti-tumor therapy for human glioblastoma.     

Smac/DIABLO与Livin在乳腺癌组织表达及其临床意义

目的：探讨凋亡促进因子Smac/DIABLO和凋亡抑制因子Livin在人乳腺癌组织中的表达及相关性,分析其与乳腺癌转移复发的关系。方法：应用免疫组织化学SP法检测76例乳腺癌组织和相应的癌旁组织中Livin和Smac蛋白的表达情况。结果：76例乳腺癌组织中Livin蛋白表达的阳性率为67.8%（51/76）,显著高于相应的癌旁组织的59.2%（36/76）,P〈0.05;乳腺癌组织中Smac表达为52.6%（40/76）,显著低于癌旁组织的75.0%（57/76）,P〈0.05。两者的表达与组织学分级、肿瘤大小、腋窝淋巴结转移以及术后复发密切相关,P〈0.05。Livin和Smac表达呈显著负相关,γ=-0.238,P〈0.05。结论：Livin的高表达及Smac/DIABLO的低表达或失活可能在乳腺癌的发生、发展中起重要作用。