RNA干扰沉默STAT3基因对肝癌细胞株HepG2和SMMC-7721的影响

肝细胞癌是常见的危害人类健康的恶性肿瘤之一,其发生、发展过程受诸多因素的影响.近年研究发现,信号转导和转录激活因子(STAT)具有强烈的抑制细胞凋亡,促进细胞增殖的作用,参与了人类恶性肿瘤的发生、发展和演变,其中以STAT3尤为活跃.本研究利用RNA干扰(RNAi)技术,用短发夹样RNA(shRNA)设计并构建RNAi-DNA质粒,筛选稳定表达小干扰RNA(siRNA)的肝癌HepG2及SMMC-7721细胞株,体外研究siRNA稳定和特异性诱导肝癌STAT3基因转录后沉默并逆转其恶性表型的能力,从而探索肝癌治疗的新方法.     

Polo样激酶1基因在大鼠肝再生和肝卵圆细胞增殖中的差异表达

肝脏具有很强的再生能力,当发生轻、中度肝损害时,肝细胞可经增殖和分化等复杂过程完成肝再生;而在肝细胞大量损害或肝细胞增殖能力被抑制时,卵圆细胞可增殖并分化为肝细胞或胆管细胞.然而,目前研究结果已初步证实肝细胞癌的发生也源起于卵圆细胞,其分子机制仍有待深入研究[1-3]. Polo样激酶1(Plk1)属于保守的丝氨酸/苏氨酸激酶家族,在调控细胞周期进程和细胞分裂方面起着十分重要的作用[4-6].研究结果表明,Plk1在肝癌中的表达增强[7-8].我们在前期研究中也发现Plk1基因在肝细胞癌中差异表达[9].但是Plk1在肝卵圆细胞中的表达及其病理意义鲜见报道.本研究以二乙酰胺基芴(2-AAF)为致癌物诱导大鼠肝卵圆细胞增殖,与单纯肝再生组织进行对比分析,探讨Plk1在肝卵圆细胞中的表达及其与癌前状态的关系.     

靶向cyclinE小干扰RNA对肝癌HepG2细胞增殖和凋亡的影响

目的:以cyclinE基因编码区为靶位,构建表达小干扰RNA(siRNA)的质粒载体,观察转染后对HepG2细胞的影响.方法:针对cyclinE基因序列构建表达siRNA的真核表达载体pSilencer3.1-H1hygro,利用脂质体Metafectene转染CyclinE基因高表达的肝癌细胞株HepG2.流式细胞仪检测细胞周期及凋亡率,MTT法检测细胞增殖活性,RT-PCR和Western blot法观察转染后细胞cyclinE基因表达.结果:成功构建了表达siRNA的真核质粒载体,转染后cyclinE基因mRNA及蛋白表达水平分别下降了79%和65%.结论:靶向cyclinE基因的siRNA可有效沉默HepG2细胞高表达的cyclinE基因,从而抑制肝癌细胞的增殖并促进凋亡.     

小干扰RNA干扰高迁移率族蛋白1对HepG2细胞增殖和凋亡的影响

目的 探讨小干扰RNA(siRNA)抑制高迁移率族蛋白1(HMGB1)基因对人肝癌细胞株HepG2细胞增殖和凋亡的影响. 方法设计并化学合成针对HMGB1的3对siRNA分子序列(siRNAH1、siRNH2、siRNAH3),同时设未转染对照组(Lipo组)及转染阴性siRNA组(阴性siRNA对照组).脂质体法瞬时转染HepG2细胞,通过PCR法和Western blot检测细胞中HMGB1基因在mRNA水平和蛋白质水平的变化,利用四甲基偶氮唑盐法检测转染HMGB1-siRNA的HepG2细胞增殖情况,TdT酶介导的缺口末端标记法检测细胞凋亡情况.两组数据间比较用t检验,组内数据比较用方差分析,细胞增殖数据采用可重复双因素方差分析.结果 3对特异性HMGB1-siRNA转染后,HMGB1 mRNA相对表达量分别为1.147±0.024、1.014±0.042和0.435±0.055,较Lipo组的1.411±0.065明显减少(t值分别为7.187、9.018和20.689,P值均＜0.01);HMGB1蛋白相对表达量分别为0.369±0.035、0.340±0.028和0.097±0.020,较Lipo组的0.553±0.051明显减少(t值分别为6.678、7.919和17.287,P值均＜0.01),其中以siRNAH3抑制效果最好,抑制率可达到80%.转染siRNAH3后HepG2细胞的增殖能力受到明显抑制,与Lipo组相比,72、96、120h时F值分别为34.651、540.550、3778.197,P值均＜0.01,HepG2细胞凋亡指数明显增高(F=130.696,P＜0.01).结论 靶向HMGB1基因的siRNA分子片段可以有效地抑制HepG2细胞生长,促进HepG2细胞凋亡,其作用与下调HMGB1的表达有关,HMGB1可能是肝癌治疗的一个潜在靶点.     

RNA介导survivin基因沉默对肝癌细胞HepG2细胞株凋亡及增殖的影响

目的观察靶向封闭survivin基因对肝癌细胞株HepG2增殖和凋亡的影响,探讨survivin基因在肝癌的发生、发展中的作用。方法设计1对survivin-siRNA,体外转录制备siRNA。应用脂质体转染技术将survivin-siRNA转染肝癌细胞株HepG2,应用有荧光标记的非特异性小分子siRNA检测转染效率;RT-PCR检测survivin-mRNA水平;SABC免疫组化染色技术检测survivin蛋白表达情况;MTT法检测细胞生长情况;流式细胞仪分析细胞凋亡。结果转染survivin-siRNA可使HepG2细胞survivin-mRNA水平下降53.8%,并可使survivin蛋白表达明显减少;转染survivin-siRNA对细胞增殖及细胞凋亡无明显影响(P>0.05)。结论抑制survivin表达对肝癌细胞株HePG2凋亡及增殖无明显影响。提示survivin在肝癌细胞增殖与调亡调控中所起的作用可能并非是关键性的。     

端粒酶逆转录酶小干扰RNA对肝癌细胞的体外抑制作用

目的 研究靶向人端粒酶逆转录酶(hTERT)的小干扰RNA(siRNA)在肝癌细胞SMMC-7721中抗肿瘤作用。方法 针对hTERT基因编码区及非编码区，采用T7转录系统在体外合成了2条siRNA，转染SMMC-7721细胞。以四甲基偶氮唑盐试验、逆转录聚合酶链反应及western blot观察其对SMMC-7721细胞增殖、hTERT mRNA及蛋白表达的影响。结果 2条siRNA以剂量依赖性方式抑制了SMMC-772l细胞增殖，当给药浓度为100nmol／L时，对hTERT mRNA及蛋白表达有明显的抑制作用。结论 靶向hTERT的siRNA对hTERT基因表达有抑制效果，有可能发展为一种新的抗肿瘤药物。     

RNA干扰HIF-1α对食管癌细胞株TE13的生物学特性的影响

目的:探讨HIF-1α仅沉默后对食管癌细胞株TE13的生物学行为的影响.方法:应用倒置荧光显微镜观察HIF-1α的干扰质粒转染食管癌细胞TE13后绿色荧光蛋白的表达:采用、Western blot方法检测HIF-1α蛋白的表达;四甲基偶氮唑蓝(MTT)法检测转染前后细胞增殖能力的变化:Transwell方法检测干扰前后细胞迁移能力的变化;流式细胞术检测干扰前后细胞周期的变化.结果:TE13/12单克隆干扰效果好,Westernblot结果显示无HIF-1α表达.HIF-1α被干扰后,细胞增殖能力明显减弱(p<0.05),运动迁移能力显著下降,与未转染的细胞相比穿过人工基底膜的细胞数明显减少(18.2±3.7 VS 103.8±8.5,P<0.05).与未转染组相比,TE13/12的细胞周期发生变化,G2/M期细胞明显减少(5.99%±1.19% vs 20.47%±4.30%,P<0.05),S期增加(64.67%±1.98%VS 48.53%±3.89%,P<0.05).结论:RNA干扰可引起TE13中HIF-1α的沉默,而HIF-1α表达下调后食管癌细胞株TE13的增殖与迁移能力均减弱.推测阻断HIF-1α通路有可能成为治疗人食管鳞癌的新靶点.     

RNA干扰诱导肝癌HepG2细胞凋亡对丹参酮ⅡA药物敏感性的影响

目的:探讨载体介导的RNA干扰技术诱导HepG2细胞凋亡对丹参酮ⅡA药物敏感性的影响.方法:应用靶向细胞周期E(cyclin E)基因的siRNA真核表达载体转染HepG2细胞诱导凋亡,再以丹参酮ⅡA处理48h(cyclinE siRNA+丹参酮ⅡA组),同时设立cyclin EsiRNA组、无义siRNA组、丹参酮ⅡA组以及空白对照组,流式细胞仪检测细胞周期及凋亡率,吖啶橙荧光染色检测细胞凋亡形态,Western blot法观察细胞Caspase-3蛋白表达.结果:单用cyclinE siRNA质粒转染或丹参酮ⅡA处理肝癌HepG2细胞,细胞凋亡率显著高于空白对照组(P＜0.01),2μg/ml剂量凋亡率分别达到21.6%、23.6%.cyclinE siRNA质粒转染预诱导再经丹参酮ⅡA处理,HepG2细胞G0～G1期比例显著增高,S期、G2～M期细胞所占有比例明显下降;与单用cyclinE siRNA质粒转染、丹参酮ⅡA两组比较,细胞凋亡率分别增高了1.81和1.61倍,比两组合计增高0.35倍,Caspase-3蛋白表达水平分别增高了0.91倍和0.66倍.结论:通过cyclinE siRNA质粒转染诱导的HepG2细胞凋亡可提高丹参酮ⅡA药物敏感性,其机制与增强凋亡控制相关基因表达有关.     

RNA干扰PKM2对食管癌细胞株Eca109生物学特性的影响

目的将靶向PKM2的siRNA转染食管癌细胞株Eca109,观察转染后细胞内PKM2基因的表达变化及其对Eca109细胞增殖和周期的影响。方法将人工合成的针对PKM2基因的siRNA片段通过Lipofectamine 2000转染食管癌细胞株Eca109;实验分为实验组、空白对照组和阴性对照组,分别用实时荧光定量聚合酶链反应(real-time quantita-tive PCR,qRT-PCR)和Western blot法检测各组细胞中PKM2的mRNA和蛋白质的表达量,并用MTT法检测各组细胞的增殖活力,流式细胞仪检测细胞周期的变化。结果与空白对照、阴性对照比较,实验组细胞中PKM2 mRNA及蛋白表达减少(P<0.05),Eca109细胞转染PKM2 siRNA后,增殖能力减弱,细胞周期被阻滞在G0/G1期。结论 PKM2对Eca109细胞的生长起促进作用。     

小干扰RNA沉默脂肪酸合酶基因对人肝细胞株HepG2脂代谢的影响

目的:研究基因干扰技术沉默脂肪酸合酶(FAS)基因后对人肝细胞株HepG2细胞内外脂质含量及脂代谢相关基因表达的影响。方法:合成3对针对FAS mRNA不同位点序列的小干扰RNA(siRNA),分别转染至人肝细胞株HepG 2,实时荧光定量聚合酶链反应(PCR)检测空白对照组(HepG2细胞不经过任何处理)、阴性对照组(转染没有任何基因干扰作用的阴性siRNA)、FAS-siR NA-1转染组、FAS-siRNA-2转染组和FAS-siRNA-3转染组的FAS mRNA的表达。蛋白免疫印迹(Western blot)法检测蛋白质的表达水平,筛选出沉默效果最佳的一对siR NA。将最有效siRNA转染至HepG2细胞,48 h后测定细胞内外甘油三酯及总胆固醇含量以及脂代谢相关基因的mRNA表达水平。结果:25 nmol/L si RNA和3μl/孔(24孔板)转染试剂的转染效率最高。FAS-siRNA-3对HepG2的FAS基因的沉默效果最好,FAS-si RNA-3转染组的FAS在mRNA水平和蛋白水平分别降低为空白对照组的(52.33±3.07)%和(51.57±3.14)%。FAS-siRNA-3沉默FAS基因后HepG2的细胞内和细胞外培养液中甘油三酯含量显著低于空白对照组,细胞外总胆固醇含量显著低于空白对照组。与空白对照组比较,FAS-siRNA-3转染组HepG2的肝脂酶基因mRNA表达水平显著升高(P0.0001),微粒体甘油三酯转运蛋白基因mRNA表达水平显著降低(P0.05),差异均有统计学意义。结论:FAS基因沉默可显著降低HepG2细胞内甘油三酯、细胞外培养液甘油三酯和总胆固醇的含量,需进一步的体内外实验加以验证。     

应用RNA干扰抑制端粒酶逆转录酶表达诱导HepG2细胞凋亡

人端粒酶由RNA亚单位（hTR）和蛋白组分构成。蛋白组分包括端粒酶逆转录酶催化亚基（hTERT）和端粒酶相关蛋白1（hTEPl）。hTERT表达与端粒酶活性密切相关，是细胞永生化过程中端粒酶活化的限速步骤。抑制hTERT的表达可快速诱导细胞凋亡，其机制不是通过端粒缩短所致。表明hTERT除了其蛋白催化活性外，尚可与其他分子相互作用诱导细胞凋亡。     

Specific COX-2 inhibitor NS398 induces apoptosis in human liver cancer cell line HepG2 through BCL-2

AIM: To evaluate the effects of NS-398, a cyclooxygenase-2 (COX-2) inhibitor, on the proliferation and apoptosis of HepG2 cells. METHODS: The effects of NS-398 on the proliferation of HepG2 cells were evaluated by MTT. DNA fragmentation gel analysis was used to analyze the apoptotic cells. DNA ploidy and apoptotic cell percentage were calculated by flow cytornetry. The expression of COX-2 and Bcl-2 mRNA was identified by competitive RT-PCR. Furthermore, expression level of Bcl-2 was detected using Western blot in HepG2 after treated with NS-398. RESULTS: NS-398 inhibited cell proliferation and induced apoptosis of HepG2 cells in a concentration-dependent manner. DNA ploidy analysis showed that S phase cells were significantly decreased with increase of NS-398 concentration. The quiescent GO/G1 phase was accumulated with decrease of Bcl-2 mRNA. Whereas NS-398 had no effect on the expression of COX-2 mRNA, and no correlations were found between COX-2 mRNA and HepG2 cell proliferation and apoptosis induced by NS-398 (r=0.056 and r=0.119, respectively). Bcl-2 protein level was inhibited after treated with NS-398. CONCLUSION: NS-398 significantly inhibits the proliferation and induces apoptosis of HepG2 cells. Mechanisms involved may be accumulation of quiescent GO/G1 phase and decrease of Bcl-2 expression.     

Polo-like kinase 1 expression is a prognostic factor in human colon cancer

AIM: To clarify the expression patterns and prognostic implications of the mitotic regulator Polo-like kinase 1 (PLKl) in colon cancer. METHODS: Expression of PLKl was investigated by immunohistochemistry (158 cases) and immunoblotting in tissue of colon adenomas and adenocarcinomas. PLKl expression patterns were correlated with clinicopathological parameters and patient prognosis. In addition, expression of PLKl was evaluated by immunoblot and PCR in colon carcinoma cell lines, and coexpression of PLKl with the proliferation marker Ki-67 was investigated. RESULTS: Weak PLKl expression was observed in normal colon mucosa and adenomas. In contrast, 66.7% of carcinomas showed strong expression of PLKl. Overexpression of PLKl correlated positively with Dukes stage (P<0.001), tumor stage (P= 0.001) and nodal status (P<0.05). Additionally, PLKl expression was a prognostic marker in univariate survival analysis (P<0.01) and had independent prognostic significance (RR = 3.3, P= 0.02) in patients with locoregional disease. Expression of PLKl mRNA and protein was detected in all cell lines investigated. Coexpression of PLKl and Ki-67 was observed in the majority of colon cancer cells, but a considerable proportion of cells showed PLKl positivity without Ki-67 expression. CONCLUSION: PLKl is a new prognostic marker for colon carcinoma patients and may be involved in tumorigenesis and progression of colon cancer. Strategies focusing on PLKl inhibition in vivo might therefore represent a promising new therapeutic approach for this tumor entity.     

体外培养的肝癌细胞株与正常肝细胞株蛋白质的差异表达

目的:运用SELDI蛋白质芯片技术分析体外培养的肝癌细胞株(HepG2)与正常肝细胞株(L02)蛋白质表达差异．方法:在体外培养HepG2和L02细胞株,收获细胞,将细胞用细胞裂解液裂解后,采用SELDI蛋白质芯片技术用IMAC3 及WCX2芯片检测HepG2、L02的蛋白质谱．结果:体外培养的肝癌细胞株与正常肝细胞株的蛋白质存在差异表达,IMAC3芯片共捕获61个蛋白,发现差异峰7个,与 L02细胞相比,其中3个差异蛋白在肝癌细胞中高表达,4个差异蛋白在肝癌细胞中低表达．WCX2芯片共捕获91个蛋白, 发现差异峰14个,其中3个差异蛋白在肝癌细胞中高表达,11 个差异蛋白在肝癌细胞中低表达．结论:SELDI蛋白芯片技术检测肝癌细胞株与正常肝细胞株蛋白质的差异表达方法简便,敏感性高,重复性好．     

Induction of apoptosis in human liver carcinoma HepG2 cell line by 5-allyl-7-gen-difluoromethylenechrysin

AIM： To investigate the effect of 5-allyl-7-gen-difluoromethylenechrysin （ADFMChR） on apoptosis of human liver carcinoma HepG2 cell line and the molecular mechanisms involved.METHODS： HepG2 cells and L-02 cells were cultured in vitro and the inhibitory effect of ADFMChR on their proliferation was measured by MTT assay. The apoptosis of HepG2 cells was determined by flow cytometry （FCM） using propidium iodide （PI） fluorescence staining. DNA ladder bands were observed by DNA agarose gel electrophoresis. The influence of ADFMChR on the proxisome proliferator-activated receptor γ （PPARγ）, NF-κB, Bcl-2 and Bax protein expression of HepG2 cells were analyzed by Western blotting.RESULTS： MTT assay showed that ADFMChR significantly inhibited proliferation of HepG2 cells in a dose- dependent manner, with little effect on growth of L-02 cells, and when ICs0 was measured as 8.45 μmol/L and 191.55 μmol/L respectively, the potency of ADFMChR to HepG2 cells, was found to be similar to 5-fluorouracil （5-FU, ICso was 9.27 μmol/L）. The selective index of ADFMChR cytotoxicity to HepG2 cells was 22.67 （191.55/8.45）, higher than 5-FU （SI was 7.05 （65.37/9.27）. FCM with PI staining demonstrated that the apoptosis rates of HepG2 cells treated with 3.0, 10.0 and 30.0 μmol/L ADFMChR for 48 h were 5.79%, 9.29% and 37.8%, respectively, and were significantly higher when treated with 30.0 μmol/L ADFMChR than when treated with 30.0 μmol/L ChR （16.0%） （P 〈 0.05） and were similar to those obtained with 30.0 μmol/L 5-FU（41.0%）. DNA agarose gel electrophoresis showed that treatment of HepG2 cells with 10.0 μmol/L ADFMChR for 48 h and 72 h resulted in typical DNA ladders which could be reversed by 10.00 pmol/1 GW9662, a blocker of PPARy. Western blotting analysis revealed that aEer 24 h of treatment with 3.0, 10.0, 30.0 μmol/L ADFMChR, PPARy and Bax protein expression in HepG2 cells increased but Bcl-2 and NF-κB expression decreased; however, pre-incubation with 10.0 μmol/L GW9662 could efficiently antagonize and weaken the regulatory effect of 3.0, 30.0 μmol/L ADFMChR on PPARy and NF-KB protein expression in HepG2 cells.CONCLUSION： ADFMChR induces apoptosis of HepG2 cell lines by activating PPARγ, inhibiting protein expression of Bcl-2 and NF-κB, and increasing Bax expression.     

还原型谷胱甘肽对多柔比星处理HepG2细胞株效果的影响

目的研究还原型谷胱甘肽(GSH)对多柔比星(DOX)处理HepG2细胞株增殖及凋亡的影响;探索核转录因子(NF)-κB p65、Bcl-2在DOX单药及联合GSH诱导HepG2细胞凋亡后的表达及其意义。方法实验分4组,空白组:培养液,对照组:培养液+HepG2细胞+RPMl l640培养基,DOX组:培养液+HepG2细胞+DOX,DOX+GSH组:培养液+HepG2细胞+DOX+GSH。MTT法检测HepG2细胞生长,流式细胞仪检测细胞早期凋亡率,实时荧光定量PCR法检测NF-κB p65 mRNA的表达,Western印迹检测NF-κB p65及Bcl-2的表达。结果 (1)DOX组和DOX+GSH组作用细胞24 h、48 h、72 h均能显著抑制HepG2细胞增殖,DOX组抑制率显著高于DOX+GSH组(P0.05),且抑制率具有时间和剂量依赖性。(2)对照组凋亡率为(0.733±0.153)%,DOX组凋亡率为(28.400±0.007)%,DOX+GSH组凋亡率为(15.500±0.006)%;DOX组、DOX+GSH组分别与对照组相比,差异有统计学意义(P0.01);DOX组与DOX+GSH组相比,差异有统计学意义(P0.01)。(3)两组在处理细胞24 h后,DOX+GSH组NF-κB p65mRNA表达显著高于DOX组(P0.05)。(4)DOX组NF-κB p65、Bcl-2表达较对照组增高,DOX+GSH组表达较DOX组表达增高。结论 GSH与DOX联合使用可导致DOX化疗效果下降,其机制可能是通过进一步上调NF-κB p65和Bcl-2的表达实现的。临床上使用DOX化疗的肿瘤患者应避免同时使用GSH。     

Effects of Terminalia arjuna bark extract on apoptosis of human hepatoma cell line HepG2

AIM:To investigate the effects of Terminalia arjuna(T.arjuna)extract on human hepatoma cell line(HepG2)and its possible role in induction of apoptosis.METHODS:Human hepatoma cells were treated withdifferent concentrations of ethanolic extract of T.arjunaand its cytotoxicity effect was measured by trypan blueexclusion method and lactate dehydrogenase leakageassay.Apoptosis was analyzed by light and fluorescencemicroscopic methods,and DNA fragmentation.Themechanism of apoptosis was studied with expressionof p53 and caspase-3 proteins.Glutathione(GSH)content was also measured in HepG2 cells after T.arjunatreatment.RESULTS:T.arjuna inhibited the proliferation of HepG2cells in a concentration-dependent manner.Apoptoticmorphology was observed in HepG2 cells treated with T.arjuna at the concentrations of 60 and 100 mg/L.DNAfragmentation,accumulation of p53 and cleavage ofprocaspase-3 protein were observed in HepG2 cells afterthe treatment with T.arjuna.The depletion of GSH wasobserved in HepG2 cells treated with T.arjuna.CONCLUSION:T.arjuna induced cytotoxicity in HepG2cells in vitro.Apoptosis of HepG2 cells may be due tothe DNA damage and expression of apoptotic proteins.Depletion of GSH may be involved in the induction ofapoptosis of HepG2 cells.