STAT3基因沉默对胰腺癌细胞株的增殖及对吉西他滨敏感性的影响

目的 探讨信号转导与转录激活因子3（STAT3）基因沉默对吉西他滨介导的胰腺癌细胞株增殖和凋亡及对吉西他滨治疗敏感性的影响.方法 以STAT3荧光素慢病毒及对照的海肾萤光素酶慢病毒感染6株胰腺癌细胞株（BxPC3、L3.6pl、CFPAC-1、MPanc-96,PANC1、MiaPaCa-2）及人胰腺癌导管上皮细胞株（HPDE）,检测各细胞STAT3及磷酸化STAT3（pSTAT3）蛋白的表达.应用RNA干扰技术沉默6株胰腺癌细胞株STAT3基因表达,应用蛋白质印迹法检测细胞STAT3蛋白表达,MTS法检测细胞的增殖,流式细胞仪检测细胞的凋亡.结果 6株胰腺癌细胞株STAT3及pSTAT3蛋白表达量均显著高于HPDE细胞,但胰腺癌细胞的表达量与其对吉西他滨耐药性及敏感性无明显相关.转染靶向STAT3的siRNA（siSTAT3）的BxPC3、MiaPaCa-2、PANC1、L3.6pl、CFPAC-1、MPanc-96细胞STAT3蛋白表达量分别为0.40±0.04、0.09±0.01、0.38±0.02、0.27 ±0.06、0.10±0.02、0.24±0.04,较转染阴性对照siRNA（siNC）细胞的表达量2.27±0.21、1.83 ±0.12、2.27±0.17、2.23±0.21、0.33±0.05、1.24±0.19均显著下降（P值均＜0.05）.但对细胞的增殖及凋亡无明显影响.STAT3基因沉默可以增加所有6株细胞对吉西他滨的敏感性,吉西他滨的杀伤效应增加了10％～15％.结论 STAT3表达水平同胰腺癌的化疗药物耐药性无明显相关性,沉默STAT3基因表达可增加细胞对吉西他滨耐治疗的敏感性.     

Beclinl基因沉默对胰腺癌MiaPaCa-2细胞生长的影响

Beclin1基因与酵母自噬基因Atg 6同源,是参与哺乳动物自噬体形成,调控细胞自噬过程的重要基因.Beclin1自噬基因的缺陷可能导致肿瘤细胞逃避自噬性死亡[1],而稳定转染Beclin1后可促进细胞的自噬活性,并降低了其成瘤能力[2].本研究观察沉默胰腺癌MiaPaCa-2细胞的Beclin1基因表达后对其增殖、凋亡及细胞周期分布的影响,为胰腺癌的基因治疗提供新的思路. 一、材料与方法 1.靶向Beclin1的siRNA表达载体构建：根据siRNA设计原理,由上海吉玛制药技术有限公司构建3个插入靶向Beclin1基因的siRNA（Beclin1-siRNA）质粒以及阴性对照siRNA（NC-siRNA）质粒和荧光标记的siRNA（FAM-siRNA）质粒.经筛选后选择沉默效果最好的Beclin1-siRNA序列插入表达载体U6/Neo,构建表达载体U6/Neo-shBeclin1,同时构建阴性对照载体pGPU6/Neo-shNC及荧光对照载体pGPU6/GFP/Neo-shNC.     

MicroRNA-200b在吉西他滨诱导的胰腺癌细胞株MiaPaCa-2上皮间质转化中的作用

目的 探讨MicroRNA-200b (miR-200b)在吉西他滨诱导的胰腺癌MiaPaCa-2细胞上皮间质转化(EMT)过程中的作用.方法 应用不同浓度的吉西他滨诱导MiaPaCa-2细胞,选择50％细胞生长抑制时的药物浓度(IC50),获取耐药MiaPaCa-2细胞.采用脂质体法将miR-200b和无意义小分子片段(阴性对照)分别转染MiaPaCa-2细胞,再用IC50的吉西他滨诱导细胞,获取转染miR-200b的耐药MiaPaCa-2细胞及阴性对照的耐药MiaPaCa-2细胞.倒置显微镜下观察细胞形态变化;Transwell小室测定细胞侵袭能力;实时定量PCR检测细胞miR-200b表达;蛋白质印迹法检测细胞E-cadherin、Vimentin、Zeb1、Zeb2蛋白表达.结果 吉西他滨处理后细胞体积逐渐缩小,呈纺锤样,细胞间连接减少,伪足增多,呈现间质细胞特征.耐药MiaPaCa-2细胞的穿膜数从亲本细胞的(26±3)个上升至(85±6)个,Vimentin、Zeb1、Zeb2表达分别上升至亲本细胞的(1.87±0.17)、(2.57±0.21)、(5.24±0.83)倍,miR-200b表达下降至亲本细胞的(0.36±0.01)倍,E-cadherin表达下降至亲本细胞的(0.47±0.05)倍.而转染miR-200b的耐药MiaPaCa-2细胞的穿膜数下降至(42±4)个,Zeb1、Zeb2表达下降至阴性对照的耐药MiaPaCa-2细胞的(0.36±0.07)、(0.08±0.01)倍.结论 吉西他滨诱导胰腺癌MiaPaCa-2细胞过程中细胞出现EMT,其机制可能与miR-200b表达下调有关.     

人胰腺癌吉西他滨耐药细胞株的建立及其耐药机制初步探讨

背景:吉西他滨是胰腺癌的一线化疗药物,但由于存在原发性和获得性耐药,其改善胰腺癌患者预后的作用并不明显。因此,探讨吉西他滨获得性耐药机制具有重要临床意义。目的:建立人胰腺癌吉西他滨耐药细胞株,初步探讨胰腺癌对吉西他滨的耐药机制。方法:在体外以0.5μmol/L吉西他滨持续刺激人胰腺癌细胞株SW1990,获得耐药细胞株SW1990-0.5。以CCK-8实验检测SW1990-0.5细胞株的耐药指数,细胞群体倍增实验和划痕实验分别检测亲本和耐药细胞株在体外的生长和侵袭能力,流式细胞术检测细胞周期和细胞凋亡,real-time PCR检测多药耐药相关基因MDR-1、MRP-1、BRCP和吉西他滨代谢相关酶基因dC K、RRM1、RRM2表达。结果:SW1990-0.5细胞株的耐药指数为9.32。与亲本细胞株相比,耐药细胞株体外增殖能力减弱,体外侵袭能力无明显变化;经吉西他滨作用后,耐药细胞株细胞周期无明显变化,但细胞凋亡率显著降低,MRP-1、BRCP、dC K mRNA表达降低,MDR-1、RRM1、RRM2 mRNA表达无明显变化。结论:成功建立了稳定的人胰腺癌吉西他滨耐药细胞株SW1990-0.5;胰腺癌对吉西他滨获得性耐药可能与拮抗细胞凋亡和dC K表达下调有关。     

PUMA在吉西他滨诱导胰腺癌细胞凋亡过程中的作用

目的 研究吉西他滨体外对人胰腺癌AsPC-1细胞生长的作用机制.方法 用脂质体转染法将p53正向凋亡调控因子(PUMA)反义核酸(反义PUMA cNA)的真核表达载体pcDNA3.1-PUMAAS和空载体pcDNA3.1-导入AsPC-1细胞,G418筛选阳性细胞,获得稳定转染的阳性克隆.将转染载体的AsPC-1阳性克隆细胞和未转染载体的AsPC-1细胞分别暴露于浓度1、5、10和15 μmol/ml的吉西他滨中作用72 h.RT-PCR和Western blotting检测不同组细胞经吉西他滨作用72 h后的PUMA表达;MTT检测细胞生长抑制,流式细胞仪(FCM)、Hoechst 33258荧光染色法和TUNEL法检测细胞凋亡.结果 吉西他滨促进AsPC-1细胞凋亡,抑制细胞生长,并有明显的剂量依赖性,在细胞凋亡的同时伴有PUMA表达的上调;当细胞转染PUMA反义核酸抑制PUMA表达后,受吉西他滨作用的细胞出现PUMA蛋白表达明显降低,同时伴有细胞凋亡的抑制及细胞的明显增殖.结论 吉西他滨促进体外AsPC-1细胞凋亡,并抑制其生长,其诱导凋亡与上调PUMA有关.     

siRNA靶向沉默YAP1对卵巢癌细胞skov3增殖凋亡的影响

目的探讨小干扰RNA(si RNA)靶向沉默Yes相关蛋白(YAP)1基因表达对人卵巢癌细胞skov3增殖凋亡的影响。方法采用脂质体Lipofectamine~(TM)2000将靶向干扰YAP1的siRNA转染至对数生长期skov3细胞(siYAP1组),同时设不行转染处理的对照组和转染随机序列siRNA的转染对照组(si Control组),转染48 h后采用实时定量PCR(qPCR)检测各组的YAP1 mRNA水平;采用水溶性四氮唑(WST-1)法评价各组转染后的增殖情况,分别采用AnnexinⅤ-FITC/PI双染流式细胞术及qPCR检测转染后凋亡率及凋亡相关蛋白(抗凋亡蛋白Bcl-2、Mcl-1和促凋亡蛋白Bid、Bax)的mRNA水平,PI单染流式细胞术检测转染后的细胞周期分布情况。结果 qPCR法检测发现si YAP1组转染48 h后的YAP1 mRNA水平为(0.141±0.018),低于对照组和siControl组(均P<0.05),提示在skov3细胞中靶向沉默YAP1成功;skov3细胞经siRNA靶向沉默YAP1表达后的生长增殖受明显抑制、凋亡形态明显改变及发生G0/G1期细胞周期阻滞,与对照组和siControl组相比,siYAP1组的增殖抑制率、凋亡率、促凋亡蛋白水平及G0/G1期细胞比例均升高,而促凋亡蛋白水平及S期细胞比例均降低(P<0.05);对照组和siControl组增殖、凋亡及细胞周期相关指标的差异无统计学意义(P>0.05)。结论通过siRNA在基因水平上沉默YAP1表达可抑制skov3细胞的增殖并诱发凋亡和细胞周期阻滞,在卵巢癌的靶向治疗中可能有一定前景。     

RNA干扰抑制FAK基因表达对人胰腺癌细胞凋亡及吉西他滨敏感性的影响

目的 探讨RNA干扰技术抑制黏着斑激酶（FAK）基因表达增强人胰腺癌PANC-1细胞对化疗药物敏感性及凋亡能力的研究.方法 针对FAK mRNA序列设计合成短发夹状干扰RNA（siRNA）的DNA模板,构建pRNAT-FAK重组表达载体,转染人胰腺癌PANC-1细胞;通过RT-PCR分析其对PANC-1细胞内源性FAK表达的影响;激光共聚焦显微镜检测PANC-1细胞凋亡的形态学改变;用四甲基偶氮唑蓝法观察PANC-1细胞对化疗药物吉西他滨敏感性的改变;采用分光光度计检测 Caspase 活性.结果 成功构建 pRNAT-FAK重组质粒,并成功转染PANC-1细胞;RT-PCR证实重组质粒在mRNA显著抑制FAK基因表达（P＜0.01）;吉西他滨组及吉西他滨加pRNAT-FAK组细胞则检测出明显的细胞凋亡;四甲基偶氮唑蓝结果证明在和吉西他滨联合作用下,pRNAT-FAK组PANC-1细胞的生长抑制率明显增高（P＜0.01）;Caspase 3活性明显高于空白对照绀和阴性对照组.结论 pRNAT-FAK可抑制FAK在人胰腺癌PANC-1细胞中的表达,并增强PANC-1细胞对吉西他滨敏感性.     

siRNA沉默APE1／Ref-1基因增强人胰腺癌细胞株对吉西他滨的敏感性

背景：人脱嘌呤脱嘧啶核酸内切酶／氧化还原因子-1（APE1／Ref-1）基因与肿瘤的化放疗抵抗和预后密切相关．是肿瘤基因治疗的理想靶点。目的：以RNA干扰技术靶向沉默人胰腺癌细胞株APE1／Ref-1基因,观察该方法对细胞增殖和凋亡的影响及其能否增强胰腺癌细胞对吉西他滨的敏感性。方法：将靶向APE1／Ref-1基因的小干扰RNA（siRNA）转染人胰腺癌细胞株SW1990,半定量逆转录聚合酶链反应（RT-PCR）和蛋白质印迹法检测APEl／Ref-1基因和蛋白表达,CCK-8检测细胞增殖情况,流式细胞仪和Hoechst33258染色检测细胞凋亡情况。结果：转染APE1siRNA后．SW1990细胞APE1／Ref-1mRNA和蛋白表达显著减低,蛋白表达抑制率为55．4％±3．6％;24h、48h和72h时细胞增殖抑制率分别为41．7％±2．8％、24．8％±3．7％和21．3％±9．8％：吉西他滨组、si-APE1组和联合组均可见明显细胞凋亡．联合组早期凋亡率显著高于两者单用和空白对照组（19．8％±3．5％对7．7％±1．1％、8．4％±1．0％和2．7％±1．4％．P〈0．05）,凋亡核形态学变化最为明显。结论：沉默APE1／ReG1基因能抑制SW1990细胞增殖,促进细胞凋亡,显著提高细胞对吉西他滨的敏感性。RNAi沉默APE1／Ref-1基因联合吉西他滨化疗可能成为胰腺癌治疗的新的选择。     

吉西他滨对人胰腺癌细胞系BXPC-3的放射增敏作用及其机制探讨

目的探讨吉西他滨对人胰腺癌细胞系BXPC-3的细胞毒性作用和放射增敏作用及其相关机制。方法用不同浓度吉西他滨处理BXPC-3细胞（加药组）、0.04μg/ml吉西他滨作用24 h后用不同剂量X线照射（药物＋照射组）,另设单纯照射组。采用MTT法测定吉西他滨对BXPC-3细胞生长的药物敏感性,采用MTT法检测吉西他滨10%细胞抑制浓度（IC10）,以IC10作为研究放射增敏效应的浓度进行放射增敏试验;集落形成法观察吉西他滨的放射增敏作用;流式细胞术分析细胞周期及凋亡变化;免疫细胞化学染色观察Bcl-2,Bax蛋白表达变化。结果随吉西他滨浓度增加,细胞毒性更显著,吉西他滨对人胰腺癌细胞系BXPC-3的IC10为0.04μg/ml。单纯照射组平均致死剂量、外推数均高于药物＋照射组。流式细胞仪检测结果提示,与空白组比较,加药组细胞S期比例增高,细胞Bax表达增加,Bcl-2表达下降。结论吉西他滨对人胰腺癌细胞系BXPC-3有明显的细胞毒性作用和一定的放射增敏作用,其机制可能与吉西他滨引起S期阻滞和调节凋亡相关基因的表达有关。     

HDAC1基因沉默对人胰腺癌细胞PaTu8988细胞周期的影响

目的 探讨组蛋白脱乙酰基酶1( HDAC1)基因沉默对人胰腺癌PaTu8988细胞周期影响及可能机制.方法 常规培养胰腺癌PaTu8988细胞,分为对照组、阴性siRNA转染(c-siRNA)组及15、30 nmol/L HDAC1 siRNA转染组.采用脂质体2000转染细胞48 h后,应用蛋白质印迹法检测细胞HDAC1基因沉默效率及p21基因表达;流式细胞法检测细胞周期的变化.结果 与对照组比较,30 nmol/L HDAC1 siRNA组PaTu8988细胞的HDAC1蛋白表达明显下降,P21蛋白表达明显增加;G2/M 期细胞比例显著减少[(21.48±3.67)％比(28.28±2.94)％,P＜0.05],S期细胞比例显著增加[(50.20±6.85)％比(32.49±2.78)％,P＜0.05].结论 HDACl siRNA能特异、有效地抑制人胰腺癌PaTu8988细胞HDACl的表达,引起细胞S期阻滞,其机制可能与上调p21蛋白表达有关.     

Oil A induces apoptosis of pancreatic cancer cells via caspase activation, redistribution of cell cycle and GADD expression

AIM: To explore the mechanisms of effects of oil A on apoptosis of human pancreatic cancer cells. METHODS: Cellular DNA content was analyzed by flow cytometry. Western blotting was used for caspase-3 and PARP, caspase-7, caspase-9, cytochrome c, Bcl-2, Bax, Mcl-1, cyclinA, cyclin B1, cyclin D1, cyclin E, CDK2, CDK4, CDK6, P21, P27, GADD45, GADD153. RESULTS: The caspase-3, caspase-7, and caspase-9 activities were significantly increased as well as the cleavage of caspase-3, downstream substrate poly-ADP ribose polymerase (PARP) was induced. The amount of cytochrome c in the cytosolic fraction was increased, while the amount of cytochrome c in the mitochondrial fraction was decreased after oil A treatment. The anti-apoptosis proteins Bcl-2 and Mcl-1 were decreased in parallel and Bax increased, indicating that Bcl-2 family proteins-mitochondria-caspase cascade was responsible for oil-induced apoptosis. The proportion of cells in the G0/G1 decreased in MiaPaCa-2 and AsPC-1 cells after the treatment of oil A for 24 hours. The number of cells in S phase was increased in two cancer cell lines at 24 hours. Therefore, cells were significantly accumulated in G2/M phase. The cells with a sub-G0/G1 DNA content, a hallmark of apoptosis, were seen at 24 hours both in MiaPaCa-2 and AsPC-1 cells following exposure to oil A. The expression of cyclin A and cyclin B1 was slightly decreased and cyclin D1 levels were markedly lowered in MiaPaCa-2 cells. The expression of cyclin A and cyclin B1 was markedly decreased and cyclin D1 levels were slightly lowered in AsPC-1 cells, while cyclin E was not affected and the levels of CDK2, CDK4, and CDK6 were unchanged in MiaPaCa-2 and AsPC-1 cells. In response to oil A, P21 expression was increased, but P27 expression was not affected. The expression of both GADD45 and GADD153 was increased in two cell lines following oil A treatment. CONCLUSION: Oil A induces apoptosis of pancreatic cancer cells via activating caspase cascade, modifying cell cycle progress and changing cell cycle-regulating proteins and GADD expression.     

Expression of Heat Shock Protein 70 Modulates the Chemoresponsiveness of Pancreatic Cancer

Background/Aims

Heat shock protein (HSP) 70 is constitutively overexpressed in pancreatic cancer cells (PCCs) and appears to confer protection against chemotherapeutics. We investigated whether modulating HSP 70 increases chemoresponsiveness to gemcitabine in PCCs.

Methods

Varying concentrations of quercetin and gemcitabine, either alone or in combination, were added to PCCs (Panc-1 and MiaPaCa-2). MTT assay was performed to analyze cell viability. HSP 70 expression was assessed by Western blot analysis. Apoptosis was determined by measuring caspase-3 activity. Western blot for the LC3-II protein detected the presence of autophagy.

Results

HSP 70 levels were not affected by the incubation of Panc-1 and MiaPaCa-2 cells with gemcitabine, whereas with quercetin, the levels were reduced in both cell lines. The viability of both Panc-1 and MiaPaCa-2 cells significantly decreased with gemcitabine treatment but not with quercetin. A combination of gemcitabine and quercetin decreased the viability of both cell lines in a dose-dependent manner, which was more pronounced than gemcitabine treatment alone. Treatment with either gemcitabine or quercetin augmented caspase-3 activity in both cell lines, and a combination of these compounds further potentiated caspase-3 activity. LC3-II protein expression was negligible with gemcitabine treatment but marked with quercetin. The addition of gemcitabine to quercetin did not potentiate LC3-II protein expression.

Conclusions

Modulation of HSP 70 expression with quercetin enhanced the chemoresponsiveness of PCCs to gemcitabine. The mechanism of cell death was both apoptosis and autophagy.     

RNA干扰沉默Cyclin D1基因对胰腺癌AsPC-1细胞增殖和凋亡的影响

目的探讨以细胞周期蛋白（Cyclin）D1为靶基因的RNA干扰对胰腺癌AsPC-1细胞增殖和凋亡的影响,为胰腺癌的靶向治疗提供依据。方法用含有10％FBS的DMEM培养液在37℃、5％CO2培养箱中常规培养AsPC-1细胞,至对数生长期后接种于96孔培养板中,随机分为实验组、阴性对照组、空白对照组,并采用Lipo-fectamine^TM 2000脂质体分别转染Cyclin D1-小干扰RNA（siRNA）、阴性对照siRNA、脂质体,48h时收集细胞。应用荧光定量PCR法和Western blot法分别检测细胞中Cyclin D1 mRNA和蛋白表达水平,MTT法检测细胞体外增殖活力,流式细胞仪检测细胞周期分布及凋亡率（AI）。结果与空白对照组和阴性对照组相比,实验组Cyclin D1 mRNA和蛋白表达均明显下调,细胞生长速度明显减慢,G0／G1细胞比例显著增大、S期细胞比例则明显降低、AI显著升高（P均〈0．01）。结论Cyclin D1-siRNA能通过沉默靶基因表达抑制AsPC-1细胞生长、改变细胞周期分布、诱导细胞凋亡,可作为胰腺癌基因治疗的一个有效靶点。     

ShRNA-mediated gene silencing of β-catenin inhibits growt of human colon cancer cells

AIM: To observe the gene silencing mediated by the specific shRNA targeted against β-catenin and its effect on cell proliferation and cycle distribution in the human colon cancer cell line Colo205. METHODS: Two shRNA plasmid vectors against β-catenin were constructed and transfected into Colo205 cells with LipofectamineTM2000. The down-regulations of β-catenin, c-myc and cyclinD1 expressions were detected by RT-PCR and western blot analysis. The cell proliferation inhibitions were determined by MTT assay and soft agar colony formation assay. The effect of these two β-catenin shRNAs on cell cycle distribution and apoptosis was examined by flow cytometry. RESULTS: These two shRNA vectors targeted against β-catenin efficiently suppressed the expression of β-catenin and its down stream genes, c-myc and cyclinD1. The expression inhibition rates were around 40%-50% either at the mRNA or at the protein level. The shRNA-mediated gene silencing of β-catenin resulted in significant inhibition of cell growth both on the culture plates and in the soft agar. Moreover, the cancer cells showed significant G0/G1 arrest and increased apoptosis at 72 h post transfection due to gene silencing. CONCLUSION: These specific shRNAs targeted against β-catenin could have a gene silencing effect and block the WNT signaling pathway. They could inhibit cell growth, increase apoptosis, and induce cell cycle arrest in Colo205 cells. ShRNA interference against β-catenin is of potential value in gene therapy of colon cancer.     

汉防己甲素抑制PANC-1细胞增殖作用的机制探讨

目的：探讨汉防己甲素对人胰腺癌细胞株PANC-1细胞增殖的影响及其相关机制。方法：采用MTT法观察汉防己甲素对人胰腺癌细胞株PANC-1细胞增殖的影响;流式细胞术检测其对PANC-1细胞周期及凋亡的影响;实时定量PCR检测细胞周期和凋亡相关基因P21^cip/waf1、cdc25A、c-Myc、E2F1和survivin mRNA水平的变化;Western blot检测P21^cip/waf1蛋白水平的改变。结果：MTT结果显示汉防己甲素对PANC-1细胞增殖抑制作用呈明显的剂量和时间依赖性。经汉防己甲素处理后,流式细胞术检测到明显的G1期细胞阻滞和细胞凋亡。实时定量PCR结果显示,汉防己甲素处理早期,P21^cip/waf1mRNA水平明显增加,而cdc25A、c-Myc、2F1、survivin mRNA水平均下降。Western blot结果表明P21^cip/waf1蛋白水平在汉防己甲素处理早期升高。结论：我们的研究表明汉防己甲素能有效的抑制人胰腺癌细胞株PANC-1细胞增殖。该过程可能通过上调21^cip/waf1mRNA和蛋白的表达,下调cdc25A、c-Myc、E2F1mRNA的表达,致使PANC-1细胞G1期阻滞;也可能通过下调survivin mRNA的表达,诱导PANC-1细胞凋亡。     

KAI1基因转染对乏氧培养下胰腺癌MiaPaCa-2细胞增殖、迁移及VEGF表达的影响

目的 观察转染KAI1基因的人胰腺癌MiaPaCa-2细胞在乏氧条件下培养后细胞增殖、迁移、侵袭能力的变化,探讨其可能机制.方法 应用KAl1基因过表达质粒转染乏氧条件培养后的人胰腺癌MiaPaCa-2细胞,采用蛋白质印迹法检测转染细胞KAI1、VEGF-C、VEGF-A蛋白的表达,四甲基偶氮唑蓝（MTT）法检测转染细胞的增殖,细胞划痕及Transwell小室实验观察转染细胞的迁移及侵袭能力,酶联免疫吸附测定法检测培养上清液中人VEGF-C、VEGF-A含量.结果 转染KAI1基因后的MiaPaCa-2-K细胞的KAI1蛋白表达量较未转染细胞显著增加[（0.549 ±0.021）比0].乏氧条件培养后转染细胞的增殖无明显变化,但它的迁移距离明显缩短,穿膜细胞数显著减少[（14.0±5.8）比（43.0±14.4）个,P＜0.05];细胞的VEGF-C表达显著降低[（0.218±0.043）比（0.745±0.069）.P＜0.05],但VEGF-A表达变化不显著;细胞培养上清液中VEGF-C含量显著减少[（1236±247）比（2045±221） pg/ml,P＜0.01].结论 转染KAl1基因的MiaPaCa-2细胞在乏氧条件下培养后的细胞迁移、侵袭能力减弱,其机制可能是通过下调VEGF-C的表达来抑制胰腺癌淋巴转移的.     

Identification of effective siRNA against K-ras in human pancreatic cancer cell line MiaPaCa-2 by siRNA expression cassette

AIM: We shall construct the small interfering RNA (siRNA) expression cassette (SEC) targeting activated K-ras gene sequence, identify more effective siRNA sequence against K-ras gene in human pancreatic cancer cell line MiaPaCa-2 by SEC and reveal the anti-cancer effects of RNA interference (RNAi) and its therapeutic possibilities. METHODS: Three different sites of SECs were constructed by PCR. K1/siRNA,K2/siRNA and K3/siRNA are located at sites 194,491 and 327, respectively. They were transfected into MiaPaCa-2 cells by liposome to inhibit the expression of activated K-ras. In the interfering groups of sites 194 and 491, we detected the apoptosis in cells by FACS after they were incubated for 48 h, then we tested the alternation of K-ras gene in MiaPaCa-2 cells by RT-PCR immunofluorescence, respectively. RESULTS: Introduction of the Kl/siRNA and K2/siRNA against K-ras into MiaPaCa-2 cells leads to increased apoptosis, and the number of apoptotic cells is increased compared with control cells. The tests of RT-PCR immunofluorescence show the effects of inhibiting expression of activated K-ras gene by RNA interference in the Kl/siRNA and K2/siRNA groups. We also find that the introduction of K3/siRNA has no effect on MiaPaCa-2 cells. CONCLUSION: Kl/siRNA and K2/siRNA can inhibit the expression of activated K-ras but K3/siRNA has no effect, demonstrating that Kl/siRNA and K2/siRNA are effective sequences against K-ras gene and K3/siRNA are not. We conclude that specific siRNA against K-ras expression may be a powerful tool to be used therapeutically against human pancreatic cancer.     

抑制Survivin表达对胰腺癌细胞凋亡的影响

目的 探讨以Survivin为靶基因的胰腺癌基因治疗的可能性,为胰腺癌基因治疗提供依据.方法 采用化学合成的小十扰RNA(siRNA)和pGCSi载体中的小发夹RNA(shRNA)抑制胰腺癌细胞系PaTu8988的Sunrivin基因表达,通过观察胰腺癌细胞株Survivin基因表达的下调以及细胞形态、细胞凋亡、细胞活力、凋亡信号途径等的改变评价Survivin作为靶基因的治疗效果.结果 不同序列的siRNA和shRNA抑制胰腺癌细胞Survivin的表达后,Survivin mRNA和蛋白表达水平明显下降(P<0.05);碘化吡啶(PI)染色法观察发现RNA干扰(RNAi)后细胞出现核皱缩、细胞凋亡率>20%;流式细胞仪检测发现RNAi后在G0/G1期前出现了亚二倍体峰(P<0.05);Western blot法检测发现RNAi后Casptrqe-3被激活(P<0.05).结论 通过抑制胰腺癌细胞PaTu8988的Survivin表达可以诱导肿瘤细胞启动凋亡程序,加速肿瘤细胞凋亡,由此可望提高胰腺癌的治疗效果.