抑制c-FLIP基因促进TRAIL诱导的乳腺癌细胞凋亡(英文)

目的:探讨抑制c-FLIP的表达对TRAIL诱导乳腺癌细胞MCF-7凋亡的影响。方法:重组腺病毒Ad-c-FLIP-siRNA和Ad-sTRAIL单独及联合感染对TRAIL耐药的乳腺癌细胞MCF-7,应用实时荧光定量聚合酶链反应(Real-time PCR)检测病毒感染后各组细胞内c-FLIP和TRAIL的mRNA表达变化;MTT法和结晶紫染色法检测MCF-7细胞活性,Hoechst 33258荧光染色检测各组细胞的凋亡情况。结果:与阴性对照组比较,c-FLIP-siRNA组和c-FLIP-siRNA+TRAIL组c-FLIP的mRNA相对表达量分别是(0.32±0.16)和(0.39±0.48)倍;TRAIL组和c-FLIP-siRNA+TRAIL组TRAIL的mRNA相对表达量分别是(96.21±1.54)和(87.33±1.66)倍;TRAIL组、c-FLIP-siRNA组及c-FLIP-siRNA+TRAIL组的抑制率(%)分别为(60.27±1.25)、(11.34±1.74)及(74.91±2.12)。对比阴性对照组的凋亡率(3.12±1.54),TRAIL组(12.79±2.46)和c-FLIP-siRNA+TRAIL组(25.50±3.17)组的凋亡率明显增高(P0.05),c-FLIP-siRNA组(6.85±2.82)的凋亡率变化不明显,差异无统计学意义(P0.05)。结论:siRNA抑制c-FLIP基因的表达能显著促进TRAIL对乳腺癌细胞MCF-7凋亡的诱导作用。     

抑制PI3K信号通路促进TRAIL诱导人乳腺癌细胞MCF-7凋亡

肿瘤坏死因子相关凋亡诱导配体（tumor necrosis factor-related apoptosis-inducing ligand, TRAIL）对癌细胞有独特的细胞毒性作用,而对正常细胞没有影响. 但乳腺癌细胞耐受TRAIL诱导凋亡.本研究探索磷脂酰肌醇-3激酶（phosphatidylinositol 3-kinase,PI3K）信号通路对人乳腺癌MCF-7细胞耐受TRAIL的影响. 采用MTT法、显微照相以及DAPI染色观察TRAIL对MCF-7细胞生长的抑制作用以及诱导细胞凋亡状况;流式细胞分析细胞凋亡的情况;激光共聚焦显微镜观察多聚ADP核糖多聚酶-1（poly(ADP-ribose) polymerase -1,PARP-1）的迁移和定位;Western印迹分析死亡受体、caspase-3/8、磷酸化的AKT［pAKT(Ser473)］、Src和PARP-1等蛋白质表达. 结果显示,小剂量TRAIL（< 80 nmol/L）和Ly294002（< 40μmol/L）对MCF-7细胞生长没有显著的抑制作用,但是大剂量TRAIL（160 nmol/L）和Ly294002（80 μmol/L）则能抑制MCF-7细胞生长;低剂量Ly294002协同TRAIL抑制MCF-7细胞生长,并诱导细胞凋亡;Ly294002和TRAIL共同作用能促进PARP-1从胞浆进入细胞核;蛋白质表达分析显示,MCF-7细胞均表达死亡受体DR4、DR5、诱骗受体DcR1和DcR2、以及caspase-8,但是不表达caspase-3;Ly294002和TRAIL共同作用也能抑制pAKT(Ser473)和Src的表达,并且导致PARP-1断裂. 本研究结果提示,抑制PI3K信号可增加MCF-7细胞对TRAIL诱导的敏感性;MCF-7细胞通过PI3K/AKT途径促进Src的表达耐受TRAIL的细胞毒性作用Ly294002联合TRAIL是一种新的药物组合方式治疗乳腺癌.     

RNA干扰NUP88基因对人乳腺癌MCF-7细胞生长及侵袭力的影响

目的： 构建重组慢病毒介导的NUP88-shRNA载体,通过RNAi技术分别观察沉默NUP88后对MCF-7增殖,粘附,侵袭和转移情况的影响,为乳腺癌的临床基因治疗寻找新的靶点。方法： 构建NUP88重组慢病毒表达载体,包装后检测滴度,以最佳复感染指数转染乳腺癌MCF-7细胞,利用RT-PCR和Western blot检测各组MCF-7细胞中mRNA和蛋白的表达效率;MTT法和流式细胞仪检测法,检测NUP88基因被干扰后对MCF-7细胞增殖和凋亡的影响;细胞侵袭实验检测NUP88基因被干扰后对MCF-7侵袭力的影响。结果 四组病毒及一组阴性对照均构建成功,滴度均为4E+8TU/ml;RT-PCR和Western blot检测,结果表明：经NUP88-shRNA转染的MCF-7细胞组NUP88 mRNA和蛋白质的表达与经阴性转染组和空白MCF-7细胞组相比,差异明显具有统计学意义（P<0.01）;测定NUP88-shRNA1组沉默效率最高,沉默率可达到86%;MTT法结果表明：实验组经NUP88-shRNA1慢病毒转染后细胞增殖程度显著减少,与空白组和对照组相比有显著性差异（P<0.05）。流式细胞仪检测三组MCF-7细胞凋亡结果表明：实验组经慢病毒转染后细胞凋亡率显著增加,与对照组和空白组相比有显著性差异（P<0.05）;细胞侵袭实验表明：在肿瘤细胞常规培养24h后,实验组与空白组和阴性对照组比较,穿膜细胞数量明显减少,具有显著性差异（P<0.05） 结论： NUP88重组慢病毒可以通过RNAi成功抑制MCF-7中NUP88基因的表达,并能显著抑制其增殖及远处的侵袭能力。     

靶向VEGF小干扰RNA协同5-FU诱导人乳腺癌细胞MCF-7凋亡机制的研究

探讨慢病毒介导的靶向VEGF小干扰RNA联合应用化疗药物5 FU诱导人乳腺癌细胞MCF-7凋亡的机制。以携带VEGF siRNA的慢病毒载体感染MCF-7细胞,应用RT-PCR和Western blot分别检测各组VEGF mRNA、VEGF蛋白及凋亡相关蛋白的表达,流式细胞术检测细胞凋亡。结果表明,慢病毒VEGF siRNA干扰组细胞VEGF mRNA和蛋白表达水平明显低于对照组,凋亡相关蛋白P53及P21表达上调,而SIRT1、Bcl-2及Survivin表达下调。流式细胞术检测显示慢病毒干扰组及5-FU组细胞凋亡率显著升高,联合治疗组的协同作用更为明显。上述结果表明：慢病毒介导的RNA干扰能明显抑制MCF-7细胞VEGF的表达,通过下调SIRTI蛋白的表达,导致P53蛋白表达上调,并调控其下游P21、bcl-2和Survivin的表达,从而诱导MCF-7细胞的凋亡,并且提高了MCF-7对5-FU的敏感性。     

沉默Bmi-1基因表达对MCF-7细胞阿霉素敏感性的影响

目的研究Bmi-1对MCF-7细胞阿霉素敏感性的影响及机制。方法阿霉素处理MCF-7／Bmilsi、MCF-7／GFPsi和MCF一7细胞株,M1Tr法检测阿霉素的IC50;DAPI检测阿霉素处理后细胞的凋亡,计算凋亡指数（apoptosisindex,AI）;Western印迹检测相关蛋白P53,phospho—Akt（Ser473）（pAkt）,totle—Akt（tAkt）,Bcl-2,Bax的表达。结果阿霉素处理72h的MCF-7／Bmi．1si组生长抑制率明显高于MCF-7和MCF-7／GFPsi组,MCF-7／Bmilsi组的IC50为（0．15±0．02）μg／ml,而MCF-7组和MCF-7／GFPsi组的IC50分别为（0．87±0．06）μg/ml和（0．81±0．02）μg/ml（P〈0．05）。阿霉素处理48h后用DAPI检测凋亡发现,MCF-7／Bmi．lsi＋doxorubiein组可见大量凋亡细胞,而MCF-7＋doxorubicin和MCF-7／GFPsi＋doxo—rubicin组出现较少的凋亡细胞,MCF-7／Bmi-1si＋doxorubicin组凋亡指数明显高于对照组（P〈0．05）。进一步研究发现：MCF-7／Bmi．1si＋doxorubicin组与MCF-7＋doxorubiein及MCF-7／GFPsi＋doxorubiein组相比,P53表达量增加,tAkt表达未发生改变,而pAkt的表达明显减少,另外,Bcl-2表达量减少而Bax表达量增加,差异具有显著性（P〈0．05）。结论沉默Bmi—l基因表达能增加MCF-7细胞对阿霉素的敏感性,增加阿霉素引起的凋亡。     

破壁灵芝孢子粉诱导MCF-7细胞凋亡的机理研究

目的：研究破壁灵芝孢子粉对人乳腺癌细胞系MCF-7的诱导凋亡作用。方法：在体外设定不同浓度的孢子粉处理MCF-7细胞系的实验组,细胞培养24h后,用MTT法测定其细胞活力;碘化丙啶（vI）染色后流式细胞仪检测其凋亡情况;罗丹明123（Rodamine123）标记后于酶标仪530nIn处测定其荧光强度值以检测线粒体膜电位情况。结果：与对照组相比,随孢子粉浓度的上升,MCF-7细胞活力和增殖呈剂量依赖型的下降;流式细胞仪检测PI染色显示,各处理组的MCF-7细胞凋亡率随作用浓度的上升而增强,最高浓度组尤为明显;在高浓度组,罗丹明123荧光强度明显降低。这些结果表明孢子粉能抑制MCF-7细胞的活力扣增殖;诱导其凋亡;罗丹明荧光强度的减少,说明MCF-7线粒体膜电位有倒塌扣去极化的情况发生,提示MCF-7细胞的凋亡与线粒体有关。结论：破壁灵芝孢子粉可明显促进MCF-7细胞的凋亡。     

脱氧核酶抑制Akt1基因对MCF-7乳腺癌细胞生长的影响

目的应用脱氧核酶抑制Akt1的表达,观察MCF-7乳腺癌细胞生长及凋亡情况。方法采用噻唑蓝比色法（MTT）检测脱氧核酶抑制MCF-7乳腺癌细胞增殖作用;DAPI染色法分析细胞凋亡形态学的变化;流式细胞术检测脱氧核酶对MCF-7乳腺癌细胞凋亡的影响;运用蛋白免疫印迹检测分析Akt1、pro—caspase-3、pro-caspase-9的变化。结果Aktl脱氧核酶对MCF-7乳腺癌细胞在体外的生长具有抑制作用;DRz1组的细胞早期凋亡率显著高于未处理组;荧光显微镜下可见典型的凋亡形态学变化;脱氧核酶作用后,免疫印迹检测Aktl蛋白表达降低,pro—caspase-3、9均被活化。结论AktlDRzl能有效下调MCF-7乳腺癌细胞Akt1的蛋白表达水平,抑制MCF-7细胞的生长,且凋亡途径可能依赖于caspase-3、9的相关的线粒体凋亡途径。     

RNA干涉介导的Plk1沉默对乳腺癌细胞恶性生物表型的影响

目的：研究乳腺癌细胞中丝／苏氨酸蛋白激酶Plk1基因表达下调后对其恶性生物表型的影响。方法：利用pSitencer4．1-CMVneo质粒,分别构建针对Plk1基因的RNA干涉载体（pSilencer4．1-shPlk1）,利用脂质体Lipofectamine2000转染MCF-7细胞,G418筛选稳定的转染细胞系。半定量RT—PCR和Western blot分别检测Plk1基因mRNA和蛋白表达,MTT和克隆形成试验检测细胞增殖活性的变化,流式细胞仪分析细胞周期和凋亡的变化,最后分析MCF-7细胞对紫杉类药物（紫杉醇和多西他赛）化疗敏感性的变化。结果：成功筛选了稳定转染细胞系（MCF-7／shPlk1和MCF-7／shcontro1）。同MCF-7／shPlk1细胞相比,MCF-7／shPtkl细胞中Plk1基因mRNA和蛋白表达水平分别下调65．8％和74．4％（P〈0．05）。同MCF-7／shcontrol,MCF-7tshPlk1细胞增殖速度显著抑制,到第5天时抑制率达到44．9±3．2％（P〈0．05）。同时,MCF-7／shPlk1细胞的克隆形成能力显著降低（P〈0．01）流式细胞仪技术分析细胞周期结果表明：MCF-7／shPlk1细胞的G2／M期细胞比例显著增加了21．1±4．1％,而S期细胞比例则显著降低了（18．5±3．1％;P〈0．05）。流式细胞仪技术分析细胞凋亡结果表明：MCF-7／shPlk1细胞的凋亡率约显著增加了13．1±213％（P〈0．05）,同时还发现：MCF-7／shPlk1细胞中激活的caspase-3蛋白显著增加,Bcl-2蛋白显著降低,而Bax蛋白则显著增加。结论：RNA干涉载体能特异性下调乳腺癌细胞中Plk1基因的表达,从而抑制乳腺癌细胞的增殖和体外克隆形成能力,同时诱导乳腺癌细胞的G2／M期阻滞和细胞凋亡率显著增加。因此,靶向Plk1基因的生物治疗有望成为未来临床乳腺癌的一个重要的辅助治疗策略.     

ILP-2表达上调减轻双氧水诱导的人MCF-7细胞株凋亡

为探讨乳腺癌细胞生长中凋亡抑制蛋白样蛋白2(ILP-2)对活性氧(ROS)毒性的拮抗作用,该研究用不同浓度双氧水(H_2O_2)对人乳腺癌细胞MCF-7进行氧化应激造模, 2′,7′-二氯荧光黄双乙酸盐探针法(DCFH-DA)检测乳腺癌细胞中活性氧变化,蛋白质印记法检测siRNA干扰效率及干扰后乳腺癌细胞ILP-2的表达,噻唑蓝(MTT)法检测siRNA转染及双氧水处理后乳腺癌细胞的增殖活性,划痕试验分析siRNA转染及双氧水处理对乳腺癌细胞迁移的影响,吖啶橙/溴化乙锭双荧光染色法(AO-EB)检测si RNA转染及双氧水处理对乳腺癌细胞凋亡的影响。结果显示, 200μmol/L双氧水显著诱导MCF-7中活性氧的产生。蛋白质印迹法结果显示, siRNA-5干扰效率较高;双氧水+siRNA-5组ILP-2表达高于双氧水+siRNA阴性对照组。双氧水处理细胞24、48和72 h后, MTT结果显示,细胞存活率明显低于空白对照组,双氧水+siRNA-5组细胞存活率高于双氧水+siRNA阴性对照组;划痕实验结果显示,细胞迁移率低于空白对照组,双氧水+siRNA-5组迁移率高于双氧水+siRNA阴性对照组; AO-EB结果显示,与空白对照组相比,双氧水组细胞凋亡率显著升高,双氧水+siRNA-5组细胞凋亡率低于双氧水+siRNA阴性对照组。以上结果表明,凋亡抑制蛋白ILP-2拮抗活性氧对乳腺癌细胞MCF-7的细胞毒性,促进细胞增殖。     

抑制PI3K信号通路促进TRAIL诱导人乳腺癌MCF-7细胞凋亡

肿瘤坏死因子相关凋亡诱导配体(tumor necrosis factor-related apoptosis-inducing ligand,TRAIL)对癌细胞有独特的细胞毒性作用,而对正常细胞没有影响.但乳腺癌细胞耐受TRAIL诱导凋亡.本研究探索磷脂酰肌醇-3激酶(phosphatidylinositol 3-kinase,PI3K)信号通路对人乳腺癌MCF-7细胞耐受TRAIL的影响.采用MTT法、显微照相以及DAPI染色观察TRAIL对MCF-7细胞生长的抑制作用以及诱导细胞凋亡状况;流式细胞分析细胞凋亡的情况;激光共聚焦显微镜观察多聚ADP核糖多聚酶-1(poly(ADP-ribose)polymerase-1,PARP-1)的迁移和定位;Western印迹分析死亡受体、caspase-3/8、磷酸化的AKT[pAKT(Ser473)]、Src和PARP-1等蛋白质表达.结果显示,小剂量TRAIL(80 nmol/L)和Ly294002(40μmol/L)对MCF-7细胞生长没有显著的抑制作用,但是大剂量TRAIL(160 nmol/L)和Ly294002(80μmol/L)则能抑制MCF-7细胞生长;低剂量Ly294002协同TRAIL抑制MCF-7细胞生长,并诱导细胞凋亡;Ly294002和TRAIL共同作用能促进PARP-1从胞浆进入细胞核;蛋白质表达分析显示,MCF-7细胞均表达死亡受体DR4、DR5、诱骗受体DcR1和DcR2、以及caspase-8,但是不表达caspase-3;Ly294002和TRAIL共同作用也能抑制pAKT(Ser473)和Src的表达,并且导致PARP-1断裂.本研究结果提示,抑制PI3K信号可增加MCF-7细胞对TRAIL诱导的敏感性;MCF-7细胞通过PI3K/AKT途径促进Src的表达耐受TRAIL的细胞毒性作用;Ly294002联合TRAIL是一种新的药物组合方式治疗乳腺癌.     

Chemotherapy overcomes TRAIL-R4-mediated TRAIL resistance at the DISC level

TNF-related apoptosis-inducing ligand or Apo2L (Apo2L/TRAIL) is a promising anti-cancer drug owing to its ability to trigger apoptosis by binding to TRAIL-R1 or TRAIL-R2, two membrane-bound receptors that are often expressed by tumor cells. TRAIL can also bind non-functional receptors such as TRAIL-R4, but controversies still exist regarding their potential to inhibit TRAIL-induced apoptosis. We show here that TRAIL-R4, expressed either endogenously or ectopically, inhibits TRAIL-induced apoptosis. Interestingly, the combination of chemotherapeutic drugs with TRAIL restores tumor cell sensitivity to apoptosis in TRAIL-R4-expressing cells. This sensitization, which mainly occurs at the death-inducing signaling complex (DISC) level, through enhanced caspase-8 recruitment and activation, is compromised by c-FLIP expression and is independent of the mitochondria. Importantly, TRAIL-R4 expression prevents TRAIL-induced tumor regression in nude mice, but tumor regression induced by TRAIL can be restored with chemotherapy. Our results clearly support a negative regulatory function for TRAIL-R4 in controlling TRAIL signaling, and unveil the ability of TRAIL-R4 to cooperate with c-FLIP to inhibit TRAIL-induced cell death.     

Suppression of multidrug resistance by treatment with TRAIL in human ovarian and breast cancer cells with high level of c-Myc

In this study, we investigated the role of c-Myc in overcoming multidrug resistance (MDR) in human ovarian and breast cancer cells by TRAIL. We showed that P-gp expressing MDR variants (Hey A8-MDR and MCF7-MDR cells) with high level of c-Myc were highly susceptible to TRAIL treatment when compared to their drug-sensitive parental human ovarian cancer Hey A8 and breast MCF-7 cells, respectively. Up-regulation of DR5 TRAIL receptor and down-regulation of c-FLIP and the promotion of caspase-dependent cell death, which contribute to TRAIL sensitization of MDR cells, were regulated by the over-expressed c-Myc in the MDR cells. After targeted inhibition of c-Myc with specific siRNA, these responses to TRAIL disappeared and TRAIL-induced apoptosis was also suppressed in MCF7-MDR cells. Treatment with TRAIL significantly reduced P-glycoprotein (P-gp)-mediated efflux of rhodamine123 in both Hey A8-MDR and MCF7-MDR cells. Furthermore, TRAIL significantly potentiated the cytotoxicity of vinblastine, vincristine, doxorubicin and VP-16 that are P-gp substrate anticancer drugs in both MDR cells, which resulted in the reversal effect of TRAIL on the MDR phenotype. The present study shows for the first time that elevated c-Myc expression in the MDR cells plays a critical role in overcoming MDR by TRAIL that can act as a specific sensitizer for P-gp substrate anticancer drug.     

Inhibition of CaMKII-mediated c-FLIP expression sensitizes malignant melanoma cells to TRAIL-induced apoptosis

TRAIL can induce apoptosis in melanoma cells and thus may offer new hope for melanoma therapy. However, many melanoma cells are resistant to TRAIL. To examine molecular mechanisms in cell resistance, we analyzed TRAIL-induced DISC in TRAIL-sensitive melanoma cells and showed that apoptosis-initiating caspase-8 and caspase-10 were recruited to the DISC where they became activated through autocatalytical cleavage, leading to apoptosis through cleavage of downstream substrates such as caspase-3 and DFF45. In TRAIL-resistant melanoma cells, however, c-FLIP proteins were recruited to the DISC, resulting in the inhibition of caspase-8 and caspase-10 cleavage in the DISC. Both calmodulin-dependent protein kinase II (CaMKII) protein and enzymatic activity were upregulated in resistant cells and CaMKII inhibitor KN-93 downregulated expression of c-FLIP proteins, thus sensitizing resistant cells to TRAIL-induced apoptosis. Transfection of CaMKII cDNA in sensitive melanoma cells resulted in cell resistance to TRAIL, where transfection of CaMKII dominant-negative cDNA in resistant cells restored TRAIL sensitivity in cells. These results indicate that the CaMKII-mediated pathway for c-FLIP upregulation protects melanoma cells from TRAIL-induced apoptosis and targeting this pathway may provide novel therapeutic strategies in treatment of melanomas.     

Inhibition of RIP and c-FLIP enhances TRAIL-induced apoptosis in pancreatic cancer cells

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has recently emerged as a cancer therapeutic agent because it is capable of preferentially inducing apoptosis in human cancer over normal cells. The majority of human pancreatic cancers, unfortunately, are resistant to TRAIL treatment. Here, we show that the inhibition of caspase-8 cleavage is the most upstream event in TRAIL resistance in pancreatic cancers. TRAIL treatment led to the cleavage of caspase-8 and downstream caspase-9, caspase-3, and DNA fragmentation factor 45 (DFF45) in TRAIL-sensitive pancreatic cancer cell lines (BXPC-3, PACA-2). This caspase-8-initiated caspase cascade, however, was inhibited in TRAIL-resistant pancreatic cancer cell lines (PANC-1, ASPC-1, CAPAN-1, CAPAN-2). The long and short forms of cellular Fas-associated death domain-like interleukin-1beta-converting enzyme-inhibitory protein (c-FLIP(L), c-FLIP(S)) were highly expressed in the TRAIL-resistant as compared to the sensitive cells; knockdown of c-FLIP(L) and c-FLIP(S) by a short hairpin RNA (shRNA) rendered the resistant cells sensitive to TRAIL-induced apoptosis through the cleavage of caspase-8 and activation of the mitochondrial pathway. Receptor-interacting protein (RIP) has been reported in TRAIL-induced activation of NF-kappaB and we show here that knockdown of RIP sensitized the resistant cells to TRAIL-induced apoptosis. These results indicate the role of c-FLIP and RIP in caspase-8 inhibition and thus TRAIL resistance. Treatment of the resistant cells with camptothecin, celecoxib and cisplatin resulted in the downregulation of c-FLIP and caused a synergistic apoptotic effect with TRAIL. These studies therefore suggest that combination treatment with chemotherapy can overcome TRAIL resistance and enhance TRAIL therapeutic efficacy in treating pancreatic cancers.     

全反式维甲酸联合替莫唑胺对胶质瘤U251细胞增殖与凋亡的影响

目的：研究全反式维甲酸（ATRA）联合替莫唑胺（TMZ）对胶质瘤细胞株U251增殖及凋亡的影响。方法：体外培养胶质瘤细胞株U251,分为ATRA组、TMZ组、ATRA＋TMZ组和空白对照4组,应用MTT法测定U251细胞生长抑制率,流式细胞仪检测细胞周期分布和细胞凋亡率,westernblot法检测细胞维甲酸受体β（RARβ）蛋白和凋亡相关蛋白Caspase．3蛋白的表达情况。结果：对照组、ATRA组、TMZ组及ATRA＋TMZ组的细胞生长抑制率分别为（1．72±0．12）％、（9．87±0．87）％、（23．87＋1．32）％及（35．74±1．44）％,ATRA＋TMZ组的细胞生长抑制率显著高于单独应用TMZ（P〈0．01）。对照组、ATRA组、TMZ组及ATRA＋TMZ组的细胞凋亡率分别为（1．32±0．11）％、（4．16±0．35）％、（8．44±0149）％、（15．27±1．03）％,ATRA＋TMZ组的凋亡率显著高于单独应用TMZ有更高的凋亡率（P〈0．01）。对照组、ATRA组、TMZ组及ATRA＋TMZ组RARp蛋白相对表达量分别0．452±0．054、0．837±0．068、0．195±0．021、0．376±0．039,ATRA＋TMZ组RARβ蛋白相对表达量显著高于TMZ组（P〈0．01）。ATRA＋TMZ组Caspase．的3蛋白表达相对水平为（0．832±0．059）,明显高于ATRA组（0．334±0．041）及TMZ组（0．521＋0．032）,差异具有统计学意义（P〈0．01）。结论：全反式维甲酸联合替莫唑胺能更有效抑制U251细胞的增殖,增加其凋亡率,这可能与其增加RARβ和Caspase-3蛋白的表达抑制U251细胞增殖、诱导细胞凋亡有关。     

肿瘤干细胞标记物CD133与miR-429在大肠癌组织中的表达及其相关性研究

目的：检测CD133不同亚群大肠癌细胞HT-29的miR-429表达情况,探讨miR-429及CD133的表达与肿瘤的发生发展之间的关系。方法：采用荧光活化细胞分选法（FACS）分选出CD133不同亚群细胞,实时荧光定量PCR分别检测两组细胞miR-429的表达,合成miR-429寡核苷酸和阴性对照miRNA并分别转染CD133＋和CD133＋两个亚群细胞。再将细胞种植于非肥胖糖尿病／严重联合免疫缺陷（NOD／SCID）小鼠体内构建移植瘤模型,不同时间测量肿瘤体积和重量,RT—PCR及蛋白质印迹检测CD133＋和CD133＋两组肿瘤CD133mRNA和蛋白质表达。结果：血清检出CD133＋细胞为67．9％,miR-429的表达量是CD133＋细胞的（1．83±0．91）倍（P〈0．05）,CD133＋比例与miR-429表达呈负相关（r=0．591,P〈0．05）;miR-429＋／CD133＋组的移植瘤体积及重量与对照组比较有统计学差异（P〈0．05）,且miR-429＋/CD133＋组成瘤时间较对照组晚约2周,但miR-429＋/CD133＋组的移植瘤CD133表达量低,与阴性对照组比较无明显差异（P〉0．05）。结论：miR-429可能作为CD133的负性调控因子,具有抑制肿瘤生长的作用,但miR-429与CD133在肿瘤发生、发展过程中的作用机制有待进一步研究阐明。     

阿霉素与青蒿素半乳糖苷联合用药对乳腺癌细胞的体外抑制作用及机制

目的：青蒿素及其衍生物具有抗癌活性,本研究旨在探讨阿霉素（DOX）与青蒿素半乳糖苷（AG）联合用药对乳腺癌细胞的体外抑制作用及机制。方法：DOX与AG联合对乳腺癌MCF-7细胞株进行干预,MTT法评价二者对癌细胞增殖的影响;流式细胞计量术检测细胞凋亡;免疫印迹法检测凋亡相关蛋白表达情况。结果：DOX与AG联合作用对MCF-7细胞增殖抑制率最高可达91．6％,均显著高于同浓度DOX或AG抑制效果（P〈0．01）,且浓度分别为10IzM和20μM量效比最佳。10斗MDOX＋20μMAG联合干预纽癌细胞凋亡率为19．8％,显著高于对照组及单用10μMDOX或20／zMAG干预组。DOX与AG联合给药比单独应用其中一种均更加显著激活caspase级联信号通路,进而更加有效的促进癌细胞凋亡。结论：DOX和AG联合用药对人乳腺癌MCF-7细胞具有协同抑制效应,其机制可能与caspase家族介导的蛋白酶级联反应以及PARP裂解失活有关。这项研究为提高DoX治疗乳腺癌的有效性提供了新的思路。     

c-FLIP Degradation Mediates Sensitization of Pancreatic Cancer Cells to TRAIL-Induced Apoptosis by the Histone Deacetylase Inhibitor LBH589

Great efforts have been made to develop novel and efficacious therapeutics against pancreatic cancer to improve the treatment outcomes. Tumor-necrosis factor-related apoptosis-inducing ligand (TRAIL) is such a therapeutic cytokine with selective killing effect toward malignant cells. However, some human pancreatic cancers are intrinsically resistant to TRAIL-mediated apoptosis or therapy. In this study, we have shown that the histone deacetylase inhibitor LBH589 can synergize with TRAIL to augment apoptosis even in TRAIL-resistant cells. LBH589 decreased c-FLIP levels in every tested cell line and survivin levels in some of the tested cell lines. Enforced expression of ectopic c-FLIP, but not survivin, abolished the cooperative induction of apoptosis by the combination of LBH589 and TRAIL, indicating that c-FLIP downregulation plays a critical role in LBH589 sensitization of pancreatic cancer cells to TRAIL. Moreover, LBH589 decreased c-FLIP stability and the presence of the proteasome inhibitor MG132 prevented c-FLIP from reduction by LBH589. Correspondingly, we detected increased levels of ubiqutinated c-FLIP in LBH589-treated cells. These data thus indicate that LBH589 promotes ubiqutin/proteasome-mediated degradation of c-FLIP, leading to downregulation of c-FLIP. Collectively, LBH589 induces c-FLIP degradation and accordingly sensitizes pancreatic cancer cells to TRAIL-induced apoptosis, highlighting a novel therapeutic regimen against pancreatic cancer.     

人参皂甙Rb1对香烟烟雾诱导的大鼠神经细胞凋亡和细胞内Ca抖浓度的影响

目的：探讨人参皂甙Rb1（GRb1）对香烟烟雾诱导的大鼠神经细胞凋亡和细胞内Ca^2±浓度的影响。方法：雄性Wistar大鼠48只,随机分为对照组、吸烟组和GRb1组,每组16只。吸烟组和GRbI组连续吸烟12周制作吸烟大鼠模型,期间每周给予GRb1组和吸烟组大鼠分别腹腔注射40mg／kg的GRb1和等量生理盐水,对照组不做任何处理。提取大鼠大脑皮层组织,TUNEL法检测各组细胞凋亡情况,荧光分光光度法检测细胞内Ca^2±浓度变化情况。结果：TUNEL法检测表明,未经香烟烟雾处理的对照组大鼠大脑皮层细胞自然凋亡率为2．54±0．92个／视窗。连续吸烟12周,吸烟组大鼠大脑皮层细胞凋亡率较对照组显著升高,达20．62±2．13个／视窗（q=35．72,P〈0．01）。GRb1组细胞凋亡率虽也有增加,为11．48±2．37个／视窗,明显低于吸烟组（q=15．39,P〈0．01）。对照组、吸烟组和GRb1组大鼠大脑皮层细胞内Ca^2±浓度分别为236．62±12．52ng／L、636．37±18．63ng／L和353．61±13．72ng／L．GRb1组Ca^2＋浓度显著低于吸烟组（q=54．73,P〈0．01）。结论：GRb1对吸烟大鼠脑损伤的保护作用可能与抑制细胞内的Ca^2＋超载、降低香烟烟雾诱导的神经细胞凋亡有关。