RNA干扰ERCC1基因表达对肺腺癌细胞A549/DDP顺铂耐药的影响

背景与目的核苷酸切除修复机制可修复顺铂(DDP)造成的DNA损伤,作为其中的关键酶之一,切除修复交叉互补基因1(excision repair cross-complementing gene 1,ERCC1)的表达可能与DDP耐药有关.本研究旨在探讨小干扰RNA沉默ERCC1基因表达对肺腺癌耐药细胞A549/DDP药物敏感性的影响.方法将体外设计合成针对ERCC1的小分子RNA(siRNA)转染A549/DDP细胞,RT-PCR检测ERCC1 mRNA水平;Western blot检测ERCC1蛋白表达的变化;MTT检测RNA干扰后细胞药物敏感性改变.结果 ERCC1 RNAi干扰后ERCC1 mRNA表达指数降低,明显低于对照组,干扰后ERCC1 mRNA表达抑制率为90.4%.转染ERCC1 siRNA降低TERCC1蛋白的表达水平.MTT显示分别用2μg/mL、4μg/mL、8μg/mL、16μg/mL、32μg/mL顺铂处理细胞48 h,转染ERCC1 siRNA细胞组较对照组敏感性明显增高,干扰前A549/DDP细胞IC50为12.49μg/mL,干扰后A549/DDP细胞IC50下降为9.27 μg/mL.结论 ERCC1siRNA干扰可以降低ERCC1的表达水平,并可提高A549/DDP细胞对顺铂的敏感性.     

顺铂对人肺腺癌细胞作用与ERCC1表达的相关性研究

背景与目的核苷酸切除修复机制可修复顺铂(DDP)造成的DNA损伤,作为其中的关键酶之一,切除修复交叉互补基因1(ERCC1)表达可能与DDP耐药有关。本研究的目的是证实ERCC1表达与DDP作用的关系,推测ERCC1在DDP耐药中的作用。方法选择人肺腺癌细胞A549及其耐DDP细胞株A549/DDP为研究对象,RT-PCR及免疫细胞化学方法检测不同浓度、不同作用时间DDP干预后细胞中ERCC1的表达,采用MTT法检测A549/DDP细胞耐药指数。结果10μmol/LDDP作用12h,A549细胞中ERCC1 mRNA表达开始增高,随着作用时间的延长,ERCC1 mRNA的表达逐渐增高,在72h组ERCC1 mRNA表达最强,为66.69%±5.30%。浓度为5μmol/L的DDP即可刺激A549细胞中ERCC1基因水平上升,而随着DDP浓度的增加,ERCC1 mRNA水平逐渐上升,20μmol/L组达高峰(79.50%±5.46%),为对照组的3.9倍。蛋白表达的增高趋势与mRNA基本平行,但二者幅度不完全一致。与亲本细胞比较,经长期小剂量DDP诱导的耐药株A549/DDP中ERCC1表达明显增高。结论随着小剂量DDP作用时间的延长,A549细胞中ERCC1 mRNA和蛋白的表达量增加,推测ERCC1可能参与了继发耐药的形成。     

TSA对人肺腺癌A549细胞裸鼠移植瘤HIF-1α、VEGF的实验研究

 目的　探讨组蛋白去乙酰化酶抑制剂曲古抑菌素A(trichostatinA ,TSA)对人肺腺癌细胞A549裸鼠HIF 1α、VEGF的影响。方法　建立人肺癌细胞A549裸鼠模型 ,瘤内注射TSA和 0 .9%saline(NS) ,对治疗后的裸鼠进行瘤体积、瘤重的检测 ;用免疫组化和原位杂交法检测瘤组织HIF 1α、VEGF的表达。结果　在实验组和对照组之间 ,瘤重差异有显著性 ,P <0 .0 5;与治疗前瘤体积相比 ,TSA治疗一周和两周后差异无显著性 ,P >0 .0 5,NS治疗一周后无显著性 ,治疗两周后差异有显著性 ,P <0 .0 5。免疫组化和原位杂交检测发现HIF 1α、VEGF表达经TSA治疗组较NS治疗组明显减弱 ,P <0 .0 5。结论　TSA能下调肿瘤细胞HIF 1α、VEGF的表达 ,TSA对人肺癌细胞A549裸鼠模型治疗有效     

雷帕霉素联合顺铂对宫颈癌Hela细胞生长和对HIF-1α与VEGF表达影响的观察

目的:探讨mTOR抑制剂雷帕霉素与顺铂联合应用对宫颈癌Hela细胞生长的抑制作用及对HIF-1α和VEGF表达的影响。方法:分别以雷帕霉素、顺铂及雷帕霉素联合顺铂处理体外培养人宫颈癌Hela细胞,采用MTT比色法检测人宫颈癌Hela细胞的抑制率,金氏公式评价两药联合用药的效果,采用RT-PCR法、蛋白质印迹法检测各组细胞HIF-1α和VEGF mRNA和蛋白的表达。结果:雷帕霉素和顺铂对宫颈癌Hela细胞的生长有明显的抑制作用,并呈剂量依赖性,分别联合应用2种浓度雷帕霉素(10和20nmol/mL)与顺铂(0.25和0.5mg/mL)协同治疗指数q值均>1.15,两者有协同作用。雷帕霉素与顺铂联合用药HIF-1αmRNA的表达为0.242±0.048,单独用药雷帕霉素组为0.428±0.068,顺铂组为0.357±0.051;雷帕霉素与顺铂联合用药组VEGF mRNA的表达为0.498±0.093,单独用药雷帕霉素组为0.651±0.112,顺铂组为0.623±0.125,联合用药组与单独用药组比较表达量明显降低,P<0.05;雷帕霉素与顺铂联合用药组HIF-1α蛋白的表达为0.514±0.092,单独用药雷帕霉素组为0.625±0.132,顺铂组为0.635±0.120;雷帕霉素与顺铂联合用药组VEGF蛋白的表达为0.409±0.082,单独用药雷帕霉素组为0.650±0.114,顺铂组为0.623±0.102,联合用药组与单独用药组比较表达量明显降低,P<0.05。结论:单独及联合应用雷帕霉素与顺铂对宫颈癌Hela细胞的生长均有抑制作用,两药联合应用有明显的协同作用,雷帕霉素联合顺铂具有明显下调HIF-1α、VEGF基因和蛋白表达的作用。     

地塞米松联合顺铂对肺腺癌 A549 细胞增殖和凋亡的影响

目的：探讨地塞米松（dexamethasone,DEX）联合顺铂（cisplatin,DDP）在体外对肺腺癌2,549细胞增殖和凋亡的影响及可能的机制。方法：体外培养人肺腺癌A549细胞。MTF法检测DDP和DEX对A549细胞增殖的影响。流式细胞术分析细胞周期及细胞凋亡。Westernblot检测DEX和DDP对A549细胞内VDR表达水平的影响。结果：地塞米松≥500nmol／L浓度时对A549细胞有一定的增殖抑制作用（P〈0．05）;〈500nmol／L浓度时对A549细胞无明显抑制作用（P〉0．05）;DDP浓度在0．3125-10ug／ml范围内对A549细胞增殖有明显的抑制作用,并呈浓度及时间依赖性（P〈0．05）。流式细胞仪检测到DDP＋DEX组的G．期细胞比例下降,s期比例上升（P〈0．05）,且细胞凋亡数目增加（P〈0．05）。Westernblot观察到DDP＋DEX组VDR表达水平明显升高（P〈0．05）。结论：DEX可能通过上调A549细胞内VDR表达水平,与顺铂协同促进细胞凋亡、诱导细胞周期阻滞,进而提高顺铂化疗敏感性。     

人肺腺癌细胞耐顺铂株A549/CDDP的比较蛋白质组学研究

背景与目的 化疗是肺癌综合治疗的重要部分,但是肿瘤细胞耐药常导致化疗失败.本研究采用蛋白组学方法研究人肺腺癌细胞A549对顺铂产生耐药性前后的蛋白表达差异,筛选有价值的靶位.方法 以顺铂为诱导药物,人肺腺癌细胞系A549为诱导对象,采用逐步增加剂量与大剂量冲击相结合的方法,诱导建立耐顺铂细胞株A549/CDDP.对A549与A549/CDDP进行蛋白组学研究,即利用双向凝胶电泳(2-DE)分离两组总蛋白后,通过图像分析寻找表达差异的蛋白,对其进行MALDI-TOF质谱分析.结果 比较两者2-DE图谱,得到差异蛋白点82个;对其中6个差异蛋白点进行肽质量指纹图分析,鉴定出葡萄糖调节蛋白75、核糖体蛋白S4、线粒体F1-ATP合酶β亚单位、免疫球蛋白重链可变区;以上差异蛋白均在耐药株中过表达,而在对照组细胞中表达下调或不表达.结论 所鉴定的差异蛋白将为阐明肺癌细胞对顺铂耐药性产生的机制提供线索,也为筛选具体潜在价值的肺癌化疗靶位提供理论依据.     

顺铂诱导人肺腺癌A549细胞系多重抗药性的形成

目的建立人肺腺癌的多重抗药细胞系－Ａ５４９／ＤＤＰ。方法采用恒定药物浓度,周期性作用的体外诱导法、ＭＴＴ法、光镜、电镜、活细胞计数法和免疫组化法进行研究。结果Ａ５４９／ＤＤＰ对顺铂抗药,对卡铂和鬼臼乙叉甙产生交叉抗药。Ａ５４９／ＤＤＰ的细胞形态发生了改变,但其体外细胞群体生长倍增时间与Ａ５４９的无差异。Ａ５４９／ＤＤＰ细胞ｂｃ１－２基因表达较Ａ５４９的增强。结论Ａ５４９／ＤＤＰ是抗药性能稳定的多重抗药细胞系,ｂＣ１－２基因过度表达可能是其多重抗药的机理之一。     

XAF1基因对顺铂诱导肺腺癌A549细胞凋亡作用的研究

目的:通过顺铂诱导人肺腺癌细胞A549的凋亡,研究X染色体连锁凋亡抑制蛋白相关因子1(X-linked inhibitor of apoptosis protein associated factor-1,XAF1)基因在A549细胞中的表达情况,初步探讨该基因在凋亡中的作用。方法:采用4μg/mL浓度的顺铂处理A549细胞,MTT法检测细胞的增殖抑制率;AnnexinⅤ/7-AAD检测A549细胞凋亡情况;RT-PCR和蛋白质印迹法分别检测A549凋亡后XAF1mRNA和蛋白的表达;Caspase-3试剂盒检测A549细胞凋亡后Caspase-3的活性。结果:用4μg/mL浓度顺铂处理A549细胞2、12和24h后,A549细胞增殖抑制率分别为(3.40±0.65)%、(8.31±0.73)%和(14.72±0.24)%,与对照组(1.03±0.28)%相比均明显增高,P值分别为0.004、0.000和0.000,细胞增殖抑制率随时间增加而增强;A549细胞凋亡率分别为(4.35±0.95)%、(9.69±2.60)%和(22.35±1.24)%,与对照组(1.39±0.21)%相比均明显增加,P值分别为0.006、0.005和0.000,细胞凋亡率随顺铂作用时间延长而增加;实验组XAF1mRNA表达水平分别为(0.199±0.029)、(0.654±0.093)和(1.216±0.101),对照组为(0.091±0.020),XAF1mRNA表达水平随作用时间的延长呈增加趋势,P值分别为0.006、0.001和0.000;实验组XAF1蛋白表达水平分别为(0.322±0.041)、(0.508±0.014)和(0.901±0.014),对照组为(0.124±0.007),XAF1蛋白表达水平随作用时间的延长呈增加趋势,P值分别为0.001、0.000和0.000;Caspase-3活性(A405nm)分别为(34.745±3.781)、(69.524±3.096)和(94.787±5.429),对照组为(21.914±1.962),Caspase-3活性随顺铂作用时间的延长而增加。结论:顺铂诱导A549细胞凋亡可以引起XAF1表达增加,且随细胞凋亡水平的提高而增加,提示XAF1可能参与顺铂诱导人肺腺癌A549细胞的凋亡过程。     

地塞米松预处理人肺腺癌 A549 细胞对顺铂抗肿瘤活性的影响

目的：探讨地塞米松（dexamethasone,DEX）预处理人肺腺癌A549细胞后,对化疗药物顺铂（cispla—tin,DDP）抗肿瘤活性的影响。方法：以不同浓度（500、1000nmol／L）DEX预先作用于人肺腺癌A549细胞12h后,再用不同浓度（1．25、2．5、5u/ml）DDP处理。流式细胞术测定细胞凋亡,细胞计数观察细胞生长密度、形态。结果：DEX对A549细胞增殖有抑制作用。DDP能够明显抑制A549细胞增殖,促进其凋亡。DEX预处理后DDP干预A549细胞的增殖抑制作用较单一用DDP增强,且随着DEX浓度的增加,其对化疗药物DDP凋亡抑制作用的影响增强。结论：DEX预处理对顺铂诱导的人肺腺癌A549细胞的凋亡具有明显的促进作用,能增强DDP的抗肿瘤活性。     

Inhibition of Notch1 reverses EMT and chemoresistance to cisplatin via direct downregulation of MCAM in triple-negative breast cancer cells

Resistance to chemotherapy continues to be a critical issue in the clinical therapy of triple-negative breast cancer (TNBC). Epithelial–mesenchymal transition (EMT) is thought to contribute to chemoresistance in several cancer types, including breast cancer. Identification of the key signaling pathway that regulates the EMT program and contributes to chemoresistance in TNBC will provide a novel strategy to overcome chemoresistance in this subtype of cancer. Herein, we demonstrate that Notch1 positively associates with melanoma cell adhesion molecule (MCAM), a unique EMT activator, in TNBC tissue samples both at mRNA and protein levels. High expression of Notch1 and MCAM both predicts a poor survival in basal-like/TNBC patients, particularly in those treated with chemotherapy. The expression of Notch1 and MCAM in MDA-MB-231 cells gradually increases in a time-dependent manner when exposing to low dose cisplatin. Moreover, the expressions of Notch1 and MCAM in cisplatin-resistant MDA-MB-231 cells are significantly higher than wild-type counterparts. Notch1 promotes EMT and chemoresistance, as well as invasion and proliferation of TNBC cells via direct activating MCAM promoter. Inhibition of Notch1 significantly downregulates MCAM expression, resulting in the reversion of EMT and chemoresistance to cisplatin in TNBC cells. Our study reveals the regulatory mechanism of the Notch1 pathway and MCAM in TNBC and suggesting that targeting the Notch1/MCAM axis, in conjunction with conventional chemotherapies, might be a potential avenue to enhance the therapeutic efficacy for patients with TNBC.     

MiR-224 promotes the chemoresistance of human lung adenocarcinoma cells to cisplatin via regulating G1/S transition and apoptosis by targeting p21WAF1/CIP1

Background:

Increasing evidence has shown that microRNAs (miRNAs) can serve as oncogenes and tumour suppressors to participate in tumour development. However, the roles of miRNAs in chemoresistance of human lung adenocarcinoma (LA) remain largely undefined.

Methods:

On the basis of miRNA microarray data, miR-224 was identified as the most upregulated miRNA in cisplatin (DDP; cis-diamminedichloroplatinum II)-resistant A549 cells compared with parental A549 cells. The aim of our study was to investigate the roles of miR-224 in the formation of DDP-resistant phenotype of LA cells and its possible molecular mechanisms.

Results:

Here we showed that miR-224 could promote the in vitro and in vivo DDP resistance of LA cells via regulating G₁/S cell cycle transition and apoptosis. p21^WAF1/CIP1, a potent cyclin-dependent kinase inhibitor, was identified as the direct and functional target gene of miR-224. Overexpression of p21^WAF1/CIP1 could phenocopy the effect of miR-224 downregulation and silencing of p21^WAF1/CIP1 could partially reverse the effect of miR-224 downregulation on DDP resistance of DDP-resistant LA cells. In addition, miR-224 could affect the G₁/S transition of cell cycle and apoptosis in LA cells through the p21^WAF1/CIP1-pRb pathway and the intrinsic mitochondrial death pathway. Furthermore, miR-224 was found to be downregulated in DDP-responding LA tissues, and its expression was inversely correlated with p21^WAF1/CIP1. Multivariate analyses indicated that the status of miR-224 might be an independent prognostic factor for predicting the survival of LA patients.

Conclusions:

Our findings shed novel light on the roles of miR-224/p21^WAF1/CIP1 signalling in the DDP resistance of LA cells, and targeting it will be a potential strategic approach for reversing the DDP resistance in human LAs.     

Nicotine increases the resistance of lung cancer cells to cisplatin through enhancing Bcl-2 stability

Background:

Nicotine is able to activate mitogenic signalling pathways, which promote cell growth or survival as well as increase chemoresistance of cancer cells. However, the underlying mechanisms are not fully understood.

Methods:

In this study, we used immunoblotting and immunoprecipitation methods to test the ubiquitination and degradation of Bcl-2 affected by nicotine in lung cancer cells. Apoptotic assay was also used to measure the antagonising effect of nicotine on cisplatin-mediated cytotoxicity.

Results:

We demonstrated that the addition of nicotine greatly attenuated Bcl-2 ubiquitination and degradation, which further desensitised lung cancer cells to cisplatin-induced cytotoxicity. In this process, Bcl-2 was persistently phosphorylated in the cells cotreated with nicotine and cisplatin. Furthermore, Akt was proven to be responsible for sustained activation of Bcl-2 by nicotine, which further antagonised cisplatin-mediated apoptotic signalling.

Conclusions:

Our study suggested that nicotine activates its downstream signalling to interfere with the ubiquitination process and prevent Bcl-2 from being degraded in lung cancer cells, resulting in the increase of chemoresistance.     

miRNA-451逆转非小细胞肺癌A549/DDP细胞对顺铂的耐药性及其机制研究

目的:探讨microRNA-451(miR-451)逆转非小细胞肺癌A549/DDP细胞对顺铂的耐药性及其可能的作用机制.方法:应用实时荧光定量PCR法(real-time fluorescent quantitative PCR,qRT-PCR)检测耐DDP细胞株A549/DDP及其亲本细胞株A549中miR-451的表达差异,同时检测A549/DDP细胞转染miR-451 mimic后miR-451表达的变化;分别应用MTT法、克隆形成实验、流式细胞术检测转染后A549/DDP细胞对DDP药物敏感度,细胞增殖能力,联合DDP处理后细胞凋亡变化;Western印迹法检测转染后A549/DDP细胞Akt、p-Akt( Ser473)、bcl-2和bax的表达变化.结果:miR-451在耐DDP细胞株A549/DDP中的表达量显著低于敏感细胞株A549 (P ＜0.05),A549/DDP细胞转染miR-451 mimic24h后,细胞中miR-451的表达水平较对照组明显提高(P＜0.05).在A549/DDP细胞中过表达miR-451可产生以下效应:相较于对照组,DDP对A549/DDP/miR-451细胞的半数抑制浓度(half inhibition concentration,IC50)减低(P＜0.05),A549/DDP/miR-451细胞的增殖能力减弱,A549/DDP/miR-451经过DDP处理后细胞凋亡增多(P＜0.05).Western印迹法结果显示,与对照组比较,转染miR-451 mimic的A549/DDP细胞p-Akt ( Ser473)、bcl-2表达水平降低;bax表达水平升高.结论:miR-451可能通过诱导细胞凋亡,抑制细胞增殖,上调bax蛋白及下调p-Akt( Ser473)、bcl-2蛋白表达而逆转A549/DDP细胞对DDP的耐药性.     

ERCC1 mRNA表达与恶性胸腹腔积液肿瘤细胞对顺铂体外药敏相关性的研究

目的：分析切除修复交叉互补基因l（excision repair egoS8 complementafion group 1,ERCC1）在恶性胸腹腔积液肿瘤细胞中的表达,探讨ERCC1 mRNA表达与患者顺铂耐药的相关性.方法：收集26例经病理确诊的恶性胸腹腔积液,分离原代肿瘤细胞,CCK8体外药物敏感性试验检测顺铂对原代肿瘤细胞的抗肿瘤作用,荧光定量RT-PCR检测细胞中药物疗效相关基因ERCC1的相对表达水平.结果：ERCCI mRNA在恶性胸腹腔积液原代肿瘤细胞中的表达水平与临床特征无相关性,但与顺铂敏感件呈负相关,低表达者对顺铂敏感性高（P=0.01）.结论：ERCC1 mRNA表达水平可以作为预测转移性胸腹腔积液患者铂类药物化疗疗效的指标之一.     

Survivin-siRNA抑制肺癌A549细胞的增殖并增强其对顺铂的敏感性

目的：构建靶向存活素（survivin）的干扰RNA（siRNA）质粒,观察其对A549细胞增殖、凋亡以及顺铂敏感性的影响。方法：应用pSilencerU6质粒构建survivinsiRNA干扰质粒,RTPCR和Western blotting检测survivin mRNA和蛋白的表达,DAPI染色法检测细胞的凋亡,MTT法检测细胞的增殖。结果：成功构建了survivinsiRNA干扰质粒。SurvivinsiRNA质粒转染可明显下调A549细胞中survivin mRNA和蛋白的表达、抑制A549细胞的增殖、促进细胞的凋亡、增强A549细胞对顺铂的敏感性。结论：SurvivinsiRNA沉默survivin在肺癌细胞中的表达能够抑制肿瘤细胞的增殖、促进细胞凋亡,并能增强肿瘤细胞对化疗药物顺铂的敏感性,survivin 可作为肺癌治疗的潜在靶点。