EZH2基因沉默对人脑胶质瘤U251细胞增殖和凋亡影响的研究

目的:研究RNA干扰技术抑制zeste基因增强子人类同源物2(EZH2)的表达对人胶质瘤U251细胞增殖及凋亡的影响.方法:构建靶向EZH2基因的shRNA质粒并转染至U251细胞中,采用RT-PCR和蛋白质印迹法检测EZH2 mRNA和蛋白的表达情况,利用四甲基偶氮哇盐(MTT)实验和Annexin V-FITC/PI流式细胞术实验观察转染后U251细胞增殖和凋亡情况.结果:靶向EZH2基因的shRNA质粒成功抑制了U251细胞EZH2基因的表达,mRNA和蛋白表达抑制率分别为56.00％和88.73％;转染shRNA EZH2后,U251细胞的生长受到明显抑制(P＜0.01),在转染96 h后,生长抑制率达35.79％;转染48 h后,U251细胞早、晚期凋亡率分别为(26.59±0.83)％和(38.63±0.80)％,较阴性质粒组和空白对照组均增加,以晚期明显,差异有统计学意义,P＜0.01.结论:EZH2基因的沉默能有效抑制胶质瘤U251细胞的增殖、促进其凋亡,提示EZH2可能成为胶质瘤基因治疗的新靶点.     

EZH2与卵巢癌合并肺部感染患者化疗铂类耐药的相关性及其机制

目的探讨EZH2(组蛋白甲基化转移酶)与卵巢癌合并肺部感染患者化疗铂类耐药的相关性及其机制。方法对人卵巢上皮性癌细胞株A2780、铂类耐药细胞株A2780/DDP分别采用免疫荧光法、RT-PCR及Western blot方法检查其EZH2蛋白及m RNA表达的水平差异,探讨EZH2对上皮性癌细胞株A2780和铂类耐药细胞株A2780/DDP表达水平的差异性。结果 3种检测方法的结果均表明EZH2(组蛋白甲基化转移酶)蛋白在A2780及A2780/DDP中的表达主要以核表达为主,且A2780/DDP中EZH2的表达明显高于A2780,差异有统计学意义(P<0.05);A2789/DDP中EZH2 m RNA的表达较A2780增加更为显著(P<0.05)。结论 EZH2(组蛋白甲基化转移酶)m RNA及蛋白在卵巢癌细胞A2780和耐顺铂细胞A2780/DDP中的表达水平的差异性表明了EZH2与卵巢癌患者铂类耐药具有一定的相关性,但其具体作用机制是通过协同DNA阻断细胞凋亡引起耐药还是通过甲基化使癌细胞对顺铂产生耐药作用还无法确定,有待进一步的分析研究。     

RNA干扰抑制ERCC1/ERCC2表达对非小细胞肺癌化疗敏感性影响观察

目的探讨利用RNA干扰技术沉默非小细胞肺癌A549和A549/顺铂(DDP)细胞株ERCC1和ERCC2的表达对DDP化疗敏感性的影响。方法设计并合成靶向基因siRNA-ERCC1和siRNA-ERCC2,并构建载体,通过前期转染A549/DDP细胞,筛选出沉默ERCC1和ERCC2基因表达最优的小分子RNA片段及最佳的作用时间,再将筛选出来的最优片段通过脂质体LipofectamineTM2000转染入A549细胞,观察其转染效率,使用RT-PCR及细胞免疫组化分别检测转染后基因及蛋白的表达变化;利用MTT法检测转染后细胞IC50,观察其对DDP耐药性的变化;再根据实验结果,从A549和A549/DDP细胞株中选定一株能够被逆转耐药的细胞接种于12只裸鼠皮下,观察裸鼠成瘤时间,并加用DDP局部化疗4次,记录肿瘤体积变化情况。结果通过siRNA-ERCC1和siRNA-ERCC2转染A549细胞株后,其ERCC1mRNA相对表达量为104.097 8±8.551 3,未转染组为128.465 6±12.360 4;ERCC2 mRNA相对表达量为90.415 7±7.882 1,未转染siRNA-ERCC2组为123.310 0±10.999 2。转染组的mRNA相对表达量均小于未转染组,P<0.05。转染A549细胞后,转染组ERCC1和ERCC2蛋白表达量分别为1.982 1±0.518 7和2.087 1±0.655 2,明显低于未转染组ERCC1(4.576 4±1.271 1)和ERCC2(5.680 0±1.416 7),P<0.01;MTT结果提示,siRNA-ERCC1和siRNA-ERCC2转染细胞A549后的IC50分别为(20.322 7±0.452 1)和(20.394 7±0.479 4)μg/mL,与未转染组(21.062 4±0.766 4)μg/mL差异无统计学意义,P>0.05;转染A549细胞后未发现逆转DDP耐药的效果,故筛选出A549/DDP细胞株。siRNA-ERCC1转染组的肿瘤体积为(144.63±7.67)mm3,siRNA-ERCC2转染组为(130.65±8.45)mm3,均明显小于未转染组的(252.35±12.36)mm3,P<0.01。结论高效的特异性siRNA能抑制非小细胞肺癌细胞中ERCC1和ERCC2基因和蛋白的表达,并能使A549/DDP细胞株对DDP的耐药性降低,但不能改变A549细胞株对DDP的耐药性。     

稳定转染Bcl-2 shRNA对胃癌细胞SGC-7901化疗敏感性的影响

目的:探讨稳定转染靶向Bcl-2基因的短发夹RNA(shRNA)对胃癌细胞株SGC-7901化疗敏感性的影响.方法:筛选出稳定转染Bcl-2 shRNA质粒的胃癌SGC-7901细胞株,将其与不同浓度的氟尿嘧啶(5-FU)或顺铂(DDP)作用,未转染的细胞作为对照.RT-PCR法检测稳定转染前后SGC-7901细胞Bcl-2 mRNA的表达水平,MTT法检测5-FU或DDP的IC50,流式细胞仪分析细胞的凋亡率.结果:稳定转染shRNA的胃癌SGC-7901细胞Bcl-2 mRNA的表达明显下降;shRNA联合5-FU的IC50为(14.36±1.63)mg/L,对照组为(35.62±1.95)mg/L,t=2.57,P＜0.05;shRNA联合DDP的半数抑制浓度(IC50)为(2.53±0.46)mg/L,对照组为(6.89±0.52)mg/L,t=2.52,P＜0.05;流式细胞术检测显示,shRNA联合化疗明显提高SGC-7901细胞的凋亡率,t=2.60,P＜0.05.结论:稳定转染Bcl-2 shRNA的胃癌SGC-7901细胞株,其Bcl-2 mRNA的表达能够在较长时间内受到抑制,并提高对化疗药物5-FU及DDP的敏感性.     

LINC01426通过EZH2调节非小细胞肺癌顺铂耐药的机制研究

目的:探讨长链非编码RNA(lncRNA)LINC01426对非小细胞肺癌(NSCLC)顺铂(DDP)耐药的影响,并研究其潜在机制。方法:体外培养A549细胞和抗DDP细胞株A549/DDP,逆转录定量聚合酶链反应(RT-qPCR)检测细胞中LINC01426、zeste增强子同源物2(EZH2)mRNA表达;LINC01426和EZH2之间的相互作用通过RNA-蛋白质相互作用预测(RIP-seq)、RNA免疫沉淀(RIP)、RT-qPCR和染色质免疫沉淀(ChIP)测定进行验证。将A549/DDP细胞分为对照组(Control组)、si-NC组、si-LINC01426组、si-LINC01426+pc-NC组、si-LINC01426+pc-EZH2组,转染培养48 h,用RT-qPCR检测各组细胞中LINC01426、EZH2 mRNA、PTEN mRNA表达,CCK-8检测细胞对DDP的敏感性,集落形成实验检测细胞增殖,流式细胞术检测细胞凋亡,蛋白质印迹(Western blot)分析细胞中EZH2、PTEN、AKT、p-AKT蛋白表达。裸鼠移植瘤模型验证LINC01426是否...     

EZH2过表达在MCF-7获得性耐药中的作用

目的 探讨EZH2过表达在MCF-7/ADR获得性耐药中的作用。方法 应用荧光定量PCR技术和Western blot技术分别检测EZH2在MCF-7和MCF-7/ADR中的mRNA和蛋白的相对表达量。将带有报告基因eGFP的EZH2 shRNA、EZH2 shRNA-scramble质粒分别转染MCF-7/ADR细胞后,用G418筛选获得稳转细胞株,应用荧光定量PCR技术验证EZH2 shRNA组EZH2 mRNA表达是否被抑制。采用WST-1方法检测EZH2 shRNA、EZH2 shRNA-scramble和阴性对照组细胞对阿霉素敏感性的变化情况。结果 MCF-7/ADR中EZH2 mRNA相对表达量约为MCF-7的2.52±1.523倍,MCF-7/ADR中EZH2蛋白相对表达量约为MCF-7的1.58±0.58倍,差异均有统计学意义(P＜0.05)。EZH2 shRNA组稳转的细胞株EZH2 mRNA的抑制率约为84%(P＜0.05),加入阿霉素后细胞增殖能力约下降25%(P＜0.05),而EZH2 shRNA-scramble组和阴性对照组加入阿霉素后细胞增殖能力无明显变化。结论 在MCF-7/ADR细胞中EZH2 mRNA和蛋白的相对表达量较MCF-7细胞高。沉默EZH2的表达有可能逆转MCF-7/ADR细胞对阿霉素的耐药性。     

沉默CtBP1基因逆转人子宫内膜癌耐药细胞株B-MD-C1(ADR+/+)的多药耐药性

目的:探讨短发夹式RNA(short hairpin RNA,shRNA)干扰羧基末端结合蛋白1(C-terminal-binding proteins 1,CtBP1)基因表达是否可以逆转多药耐药基因1(multidrug resistant gene 1,MDR1)介导的人子宫内膜癌耐药细胞株B-MD-C1(ADR+/+)的多药耐药性.方法:采用脂质体转染法将特异性的shRNA1和shRNA2及非特异性的shRNAHK质粒转染入人子宫内膜癌耐药细胞株B-MD-C1(ADR+/+)中,RT-PCR法检测各组细胞MDR1基因表达水平,Western印迹法检测各组细胞P糖蛋白(P-glycoprotein, P-gp)的表达,MTT法测定各组细胞对多柔比星的敏感性变化.结果:RT-PCR结果显示,shRNA1组和shRNA2组细胞中MDR1基因被抑制,基因表达抑制率约50%;Western印迹结果显示,shRNA1组和shRNA2组细胞P-gp蛋白的表达水平显著降低;MTT检测发现,shRNA转染48和72 h时shRNA1组和shRNA2组细胞对多柔比星的敏感性增加(P<0.01).结论:沉默CtBP1基因可抑制人子宫内膜癌耐药细胞株B-MD-C1(ADR+/+)中MDR1基因和P-gp蛋白的表达,降低细胞的耐药性.     

shRNA沉默RAGE基因表达对前列腺癌细胞增殖的抑制作用

目的:构建针对人晚期糖基化终产物受体(receptor for advanced glycation end products , RAGE)基因的特异性短发夹RNA(small hairpin RNA, shRNA)表达载体,探讨其对前列腺癌细胞DU145增殖的抑制作用.方法:设计并合成4种针对RAGE基因的特异性短链寡核苷酸,构建含shRNA RAGE的表达载体,转染高表达RAGE的亚克隆细胞株sub DU145-2C1.荧光显微镜下观察细胞转染后的情况,实时荧光定量PCR(real-time fluorescence quantitative -PCR, RFQ-PCR)检测转染shRNA后对RAGE mRNA表达的影响,Western印迹法检测对RAGE蛋白表达的影响,CCK-8法检测对细胞增殖的影响,划痕实验观察对细胞迁移能力的影响.结果:构建获得的shRNA RAGE表达载体能够有效抑制RAGE基因的表达(P<0.05),其中以shRNA RAGE -1(R1)的抑制作用最强,其对RAGE mRNA表达的抑制率为84%,对蛋白表达的抑制率为27%.细胞增殖结果显示,转染shRNA RAGE后细胞增殖能力明显降低;而细胞迁移能力则无明显变化.结论:shRNA RAGE能有效下调RAGE基因的表达水平,抑制细胞增殖.     

奥美拉唑逆转人肺腺癌耐顺铂细胞株A549/DDP耐药性的研究

目的:探讨液泡ATPase[vacuolar (H+)-ATPase, V-ATPase]非特异性抑制剂奥美拉唑(omeprazole ,OME)逆转人肺腺癌耐药细胞株A549/DDP的耐药性及可能的作用机制.方法:以非细胞毒性浓度4 μg/mL的OME预处理A549/DDP细胞24 h,再用2 μg/mL顺铂(cisplatin, DDP)处理 A549/DDP细胞.MTT法检测细胞的增殖抑制率,激光扫描共聚焦显微镜(laser scanning confocal microscope,LSCM)法间接检测细胞内pH值的变化,FCM法检测凋亡相关蛋白Bcl-2和PTEN的表达,RT-PCR法检测V-ATPase 、Bcl-2和PTEN mRNA的表达.结果:OME具有逆转A549/DDP细胞耐药性的作用,逆转倍数为1.45 (P<0.01);OME预处理后A549/DDP细胞内pH值明显降低,Bcl-2蛋白表达下降,PTEN蛋白表达增加(P<0.01).V-ATPase在亲本A549及A549/DDP细胞中相对表达量分别为0.88±0.00和0.99±0.00 (P<0.01);A549/DDP细胞中V-ATPase在有无OME预处理的情况下的相对表达量分别为1.09±0.00和1.05±0.02,差异无统计学意义.Bcl-2 mRNA相对表达量下降(P<0.01),PTEN mRNA相对表达量增加(P<0.01).结论:V-ATPase在A549/DDP细胞中高表达,OME能部分逆转A549/DDP耐药性,其作用机制可能与上调PTEN和下调Bcl-2 表达有关.     

EZH2 participates in malignant biological behavior of epithelial ovarian cancer through regulating the expression of BRCA1

Aberrant overexpression of the enhancer of zeste homolog 2 (EZH2), a histone methyltransferase inhibiting targets expression via epigenetic mechanisms, is associated with an invasive phenotype and drug resistance in ovarian cancer. Breast cancer 1 (BRCA1) gene is a well-recognized tumor suppressor, whose downregulation plays a key role in the development of ovarian cancer. In the present study, we found depletion of EZH2 increased BRCA1 protein expression and promoted its nuclear translocation, but decreased BRCA1 mRNA expression. Treatment with the Akt-1 activator insulin-like growth factor-1 (IGF-1) prevented EZH2-induced BRCA1 nuclear/cytoplasmic shuttling. Loss of BRCA1 partially rescued the effects of EZH2 downregulation on proliferation, G₂/M transition, and migration in ovarian cancer cells. However, in a cisplatin-resistant sub-line of A2780 (A2780/DDP), both EZH2 and BRCA1 were overexpressed compared with parental A2780 cells and depletion of EZH2 reduced BRCA1 expression at both mRNA and protein levels. Downregulation of EZH2 or BRCA1 sensitized A2780/DDP cells to cisplatin, whereas simultaneous inhibition of them only resulted in modest resensitization instead of showing any synergistic effect because EZH2 expression was reactivated when BRCA1 expression was very low. Accordingly, our results suggest the expression of BRCA1 is modulated by EZH2 in epithelial ovarian cancer and BRCA1 is required for the effects of EZH2 downregulation on biological behaviors of tumor cells.     

拓扑替康促人卵巢癌顺铂耐药细胞株凋亡机制的初步研究

目的探讨拓扑替康(TPT)对人卵巢癌顺铂耐药细胞株A2780/DDP和COC1/DDP的杀伤和诱导凋亡活性及其作用机制.方法用MTT比色法测定TPT对人卵巢癌顺铂耐药细胞株A2780/DDP和COC1/DDP的杀伤效应;透射电镜和DNA凝胶电泳研究TPT对靶细胞的凋亡诱导活性;Western blot检测凋亡相关蛋白bcl-2和bax的表达.结果TPT对A2780/DDP和COC1/DDP细胞均有较强的体外杀伤作用,其IC50值分别为102.91 ng/ml和111.75 ng/ml;TPT能诱导A2780/DDP和COC1/DDP细胞产生凋亡,DNA凝胶电泳呈现典型的凋亡梯度,透射电镜观察到细胞核染色质固缩、边集,胞质浓缩,出现空泡等典型的凋亡超微结构改变;TPT不影响bcl-2蛋白表达,却能上调bax蛋白表达,增大bax/bcl-2比值,且呈剂量依赖性.结论TPT对人卵巢癌顺铂耐药细胞株A2780/DDP和COC1/DDP均有明显的杀伤和促凋亡作用,其机制可能与bax基因表达上调而提高bax/bcl-2比值有关.     

细胞色素c 介导的半胱天冬氨酸蛋白酶-3活性改变与人卵巢癌顺铂耐药的关系

目的：探讨人卵巢癌顺铂耐药细胞株A2780／DDP、COC1／DDP中抗凋亡基因bcl-XL、细胞色素c的表达和半胱天冬氨酰蛋白酶－3（caspase-3)活性对人卵巢癌顺铂耐药的影响。方法：采用逆转录聚合酶链反应（RT－PCR）和Western blot检测人卵巢癌顺铂敏感细胞株A2780、COC1和顺铂耐药株A2780／DDP、COC1／DDP中bcl-XL的表达,以及顺铂作用后细胞色素c的含量和caspase-3活性的变化,并应用流式细胞仪测定顺铂作用后A2780、COC1、A2780／DDP、COC1／DDP细胞的凋亡率。结果：bcl-XL在A2780/DDP、COC1／DDP细胞中的表达明显高于A2780、COC1细胞;顺铂作用后,细胞色素c在A2780／DDP、COC1／DDP细胞中的表达明显减少,caspase-3活性和凋亡率也较A2780和COC1细胞明显降低（P＜0．05）。结论：人卵巢部细胞对顺铂产生耐药可能与细胞内bcl-XL过度表达、细胞色素c释放受抑制和caspase-3活性下降有关。     

GOLPH3沉默对顺铂诱导的人上皮性卵巢癌 A2780／DDP 细胞凋亡的影响

目的：探究 GOLPH3对顺铂诱导的人上皮性卵巢癌 A2780／DDP 细胞凋亡的影响。方法：不同浓度顺铂处理 A2780和 A2780／DDP 细胞72h,MTT 检测半数抑制浓度 IC50,Western blot 检测 GOLPH3的表达。将培养细胞分为4组：A2780组及 A2780／DDP 组（对照组、Scrambled siRNA 组、GOLPH3 siRNA 组）。40μmol／L顺铂处理48h 后,MTT 检测对细胞活性的影响,流式细胞术检测对细胞凋亡的影响,Western blot 检测对Caspase －3、p －Akt 和 p －mTOR 蛋白表达的影响。Western blot 检测 mTOR 抑制剂雷帕霉素（Rapamycin）和PI3K／Akt 抑制剂（LY294002）对 Caspase －3蛋白表达的影响。结果：顺铂处理72h 时,A2780和 A2780／DDP细胞的 IC50分别为9．8μmol／L 和60．14μmol／L。与 A2780组相比,A2780／DDP 组 GOLPH3蛋白表达明显增加（P ＜0．05）。GOLPH3 siRNA 转染可显著下调 A2780／DDP 细胞中 GOLPH3蛋白的表达（P ＜0．05）。顺铂处理后,与 A2780／DDP 对照组相比,A2780组和 A2780／DDP 细胞 GOLPH3 siRNA 转染组细胞活性显著降低,顺铂敏感性增加,细胞凋亡率和 Caspase －3蛋白表达上调,p －Akt 和 p －mTOR 蛋白表达下调;LY294002和 Ra-pamycin 处理均显著增加 Caspase －3蛋白表达（P ＜0．05）。结论：GOLPH3沉默可通过抑制 Akt／mTOR 激活促进顺铂诱导的 A2780／DDP 细胞凋亡。     

Increased removal of DNA-bound platinum in a human ovarian cancer cell line resistant to cis-diamminedichloroplatinum(II)

A human ovarian cancer cell line resistant to cis-diamminedichloroplatinum(II) (DDP) (2780CP) was compared with its DDP-sensitive parental cell line (A2780) to determine whether differences in the removal rate of DNA-bound platinum were related to resistance. Both cell lines were treated in vitro with various doses of DDP for 2 h and subsequently incubated in arginine-deficient Eagle's minimum essential medium with 2.5% dialyzed fetal bovine serum in the presence or absence of aphidicolin. After 0, 12, and 24 h, DNA was isolated from the cells and DNA-bound platinum was determined by flameless atomic absorption spectrophotometry. Binding of platinum to DNA of either cell line was a linear function of concentration ranging from 20 to 80 microM DDP. Platinum binding was almost equal at each dose in both cell lines. 2780CP cells that were 3-fold resistant to DDP lost 30.5 to 40.1% of their total DNA-bound platinum, compared with a 1.3 to 16.1% loss for A2780 cells, 12 to 24 h after a 2-h exposure to 40 microM DDP, respectively. Aphidicolin (3.0 micrograms/ml) increased the cytotoxicity in 2780CP cells by about 2-fold and caused a significant delay in the time required for platinum removal in the resistant cells (14.6 and 18.9% at 12 and 24 h). These studies indicate that the mechanism of DDP resistance in the 2780CP cell line is related to an increased ability to remove platinum-DNA adducts, and not to a difference in initial DDP binding to DNA.     

Increased accumulation of p53 protein in cisplatin-resistant ovarian cell lines

We have examined p53 protein levels in cell lines selected for resistance to the chemotherapeutic drug cis-diamminedichloroplatinum (II), cisplatin. The majority of the independent cisplatin-resistant clones isolated by a single selection with cisplatin from the ovarian tumour cell line A2780 showed increased levels of p53 protein compared to the parental cell line. Elevated p53 protein levels were also observed in cisplatin-resistant ovarian human tumour lines isolated after multiple exposures to cisplatin (A2780/cp70 and OVIP/DDP). Direct PCR sequencing of p53 cDNAs showed that both the A2780/cp70 and the parental A2780 cell lines had a wild-type p53 gene sequence. The OVI P and OVI P/DDP lines both had a heterozygous mutation at codon 126. Cell-cycle analysis after gamma-irradiation or cisplatin treatment showed evidence of a G1/S and G2/M cell-cycle checkpoint in both A2780/cp70 and the sensitive parental cell lines. However, the resistant cell line A2780/cp70 showed less inhibition of DNA synthesis after gamma-irradiation than the sensitive cell line. Transfection of a mutant p53 gene construct (containing a mutation at codon 143, val to ala) into the A2780/cp70 resistant cells conferred a significantly increased sensitivity to cisplatin, suggesting that p53 is a direct determinant of cisplatin resistance in these cells. However, expression of this mutant p53 in the A2780 cells did not affect sensitivity.     

Effect of lung resistance-related protein on the resistance to cisplatin in human ovarian cancer cell lines

The mechanisms of drug-resistance in human ovarian cancer cells have not been entirely clarified. The purpose of this study was to investigate whether LRP is involved in the resistance of ovarian cancer cell lines to cisplatin and its molecular mechanism. Human ovarian cisplatin-resistant cancer cell lines (A2780/DDP and COC1/DDP) and their parental cisplatin-sensitive cell lines (A2780 and COC1), alone or transfected with antisense LRP-specific oligonucleotides (ODN) or sense ODN, were treated with cisplatin to induce differentiation. Expression of LRP was examined by RT-PCR and Western blot analysis. The sensitivities of cells to cisplatin were assessed using sulforhodamine B (SRB) assay and flow cytometry, and the accumulation and efflux of cisplatin in the cells and isolated nuclei were examined by high performance liquid chromatographic (HPLC) assay. The expressions of LRP in A2780/DDP and COC1/DDP cells were higher than those in A2780 and COC1 cells and conferred resistance to cisplatin. Transfection of LRP AsODN into A2780/DDP and COC1/DDP cells down-regulated LRP expression and reversed the resistance phenotype. Levels of cisplatin accumulating in cells were increased by LRP-specific AsODN and anti-LRP monoclonal antibody. Isolated nuclei from A2780 and COC1 cells or A2780/DDP and COC1/DDP cells incubated with anti-LRP antibody contained more cisplatin than the nuclei of A2780/DDP and COC1/DDP cells not treated with anti-LRP antibody. Efflux of cisplatin was greater from the nuclei of A2780/DDP and COC1/DDP cells than those of A2780 and COC1 cells, and was inhibited by anti-LRP monoclonal antibody. Thus, LRP was involved in the resistance of ovarian cancer cells to cisplatin and has an important role in the transport of cisplatin both in exocytotic vesicles and between the nucleus and cytoplasm.