Small interfering RNAs targeting mutant K-ras inhibit human pancreatic carcinoma cells growth in vitro and in vivo

AIM: To investigate the effect of small interfering RNAs targeting mutant K-ras on the growth of pancreatic carcinoma cell lines in vitro and in vivo. MATERIALS AND METHODS: We cloned targeting sequence spanning codon 12 of mutant K-ras into the pSilencer-hygro plasmid, yielding two recombinant vectors with one base different. Both human pancreatic carcinoma cell lines were transfected by these two recombinant vectors. The transfected PC-7 cells were injected subcutaneously into nude mice to observe its tumorigenicity. RT-PCR and Western blot analysis were carried out to test the expression of K-ras in all of the transfected cell lines. Growth curves assay were performed to test the abilities of cells proliferation. Anti-K-ras therapy of PC-7 and Panc-1 in subcutaneous mice models were performed by intratumor injection of polyethylenimine/siRNAs complex. RESULTS: The expressions of K-ras in PC-7 cells and Panc-1 cells were significantly inhibited by corresponding small interfering RNAs. The expression of K-ras was particularly inactivated by siRNA without any base mismatch to its homologous mRNA, while this oncogene with central base mismatch could not be inhibited as effectively as that of the former. The growth of PC-7 cells and Panc-1 cells transfected by corresponding mutant K-ras targeted siRNAs were significantly suppressed when compared with controls (p<0.05). The transfected PC-7 cells lost tumorigenic ability. Four weeks treatment of Xenograft of pancreatic carcinoma (PC-7 and Panc-1) in nude mice with Polyethylenimine-encapsulated mutant K-ras targeted siRNAs (20 microg/mouse twice weekly) were effective in reducing tumor growth, when compared with controls (p<0.05). CONCLUSION: The central base may play a key role in the process of RNA interference. The mutant point and its vicinity of 19 nucleotides in K-ras may be the effective targeting sequence for RNA interference. Targeting mutant-k-ras therapy of pancreatic carcinoma may be a clinically applicable therapeutic modality.     

人ＳＴＡＴ３基因ｓｉＲＮＡ真核表达质粒的构建及鉴定

目的：构建针对人ＳＴＡＴ３基因的ｓｉＲＮＡ真核表达质粒,检测其在细胞水平对ＳＴＡＴ３基因表达的抑制效果。方法：用ＤＮＡ重组技术将针对人ＳＴＡＴ３基因ｍＲＮＡ序列不同位点设计的３个ｓｉＲＮＡ序列克隆到真核表达质粒ｐＲＮＡＴ-Ｕ６.１／ｎｅｏ中构建重组体ｐＲＮＡＴ-Ｕ６.１-ｓｉＲＮＡ,重组质粒经ＰＣＲ检测及测序分析,用脂质体转染重组质粒至人食管癌Ｅｃａ-１０９细胞,Ｇ４１８筛选获得阳性克隆,ＲＴ-ＰＣＲ和Ｗｅｓｔｅｒｎｂｌｏｔ检测ＳＴＡＴ３基因ｍＲＮＡ和蛋白的表达,筛选最佳沉默效率的ｓｉＲＮＡ。结果：ＰＣＲ检测及测序分析结果均提示重组质粒构建正确。ＲＴ-ＰＣＲ和Ｗｅｓｔｅｒｎｂｌｏｔ检测证实ｐＲＮＡＴ-Ｕ６.１-ｓｉＲＮＡ３具有最佳的沉默效率。结论：成功构建人ＳＴＡＴ３基因ｓｉＲＮＡ真核表达质粒,并证实其能够从ｍＲＮＡ和蛋白水平抑制ＳＴＡＴ３基因的表达。     

利用siRNA抑制HER-2表达的研究

目的利用siRNA抑制人乳腺癌MCF-7细胞中HER-2基因的表达。方法针对HER-2mR-NA设计了5条siRNA,并构建相应的表达质粒,将质粒转染MCF-7乳腺癌细胞,筛选稳定表达株,利用RT-PCR分析siRNA对细胞中HER-2mRNA的降解作用;利用流式细胞术分析细胞表面HER-2蛋白的表达;利用裸鼠进行体内成瘤性实验,用免疫组化法检测瘤组织中HER-2的表达。结果siRNA3P能明显降低MCF-7细胞中HER-2mRNA的丰度;流式细胞分析表明,其中siRNA2P和3P稳定转染的MCF-7细胞表面HER-2的表达明显降低;五种表达不同siRNA的MCF-7细胞在裸鼠体内的成瘤性均有所降低,并且瘤组织中HER-2蛋白的表达也明显减少。结论靶向HER-2mRNA的siRNA能在体内外有效抑制HER-2的表达,可用于乳腺癌的基因治疗。     

靶向VEGF的不对称siRNA抑制乳腺癌MCF-7细胞的增殖

目的:探讨靶向血管内皮生长因子(vascular endothelial growth factor,VEGF)基因的siRNA对乳腺癌MCF-7细胞的抑制效果。方法:设计靶向VEGF的4种小干扰RNA(small interfering RNA,siRNA),包括对称siRNA(siRNA21/21,siRNA23/23)与不对称siRNA(asymmetric siRNA,aiRNA;aiRNA21/23,aiRNA19/21)。siRNA转染入MCF-7细胞后,MTT及流式细胞术检测MCF-7细胞增殖及凋亡情况,RT-PCR、ELISA法检测MCF-7细胞中VEGF基因和蛋白的表达。结果:与对照组相比,aiRNA21/23、siRNA23/23、aiRNA19/21、siRNA21/21这4种siRNA都能有效抑制VEGF mRNA的表达[(71.4±5.01)%、(40.0±3.11)%、(37.2±2.79)%、(11.1±0.99)%vs(2.4±0.11)%,P<0.01],且抑制MCF-7细胞的增殖[(44.7±5.38)%、(38.5±5.67)%、(33.6±2.18)%、(33.1±3.18)%vs(2.2±0.28)%,P<0.01],其中以不对称aiRNA21/23的抑制效果最明显。与对照组比较,aiRNA21/23显著促进MCF-7细胞的凋亡[(49.9±4.02)%vs(4.7±0.91)%,P<0.01]。结论:靶向VEGF基因的siRNA可抑制MCF-7细胞的增殖、促进细胞凋亡,尤以不对称siRNA的效果最明显。     

Small interfering RNA expression vector targeting hypoxia-inducible factor 1 alpha inhibits tumor growth in hepatobiliary and pancreatic cancers

Hepatobiliary and pancreatic carcinomas are hypovascular tumors that can proliferate under hypoxic conditions. Recent reports have demonstrated that hypoxia-inducible factor 1 alpha (HIF1alpha) plays an important role in the survival of these cancers. Given these findings, the inhibition of the HIF1alpha pathway might prove to be a powerful tool in the treatment of these cancers. To inhibit HIF1alpha expression, we used small interference RNA (siRNA) expression vectors in this study. The transient transfection of siRNA expression vectors significantly reduced both HIF1alpha mRNA levels (13% of control) and protein levels (41% of control) and significantly inhibited the growth of cancer cell lines (P<0.05). VEGF, Glut1, and aldorase A expressions were also significantly reduced by transfection with these vectors (P<0.05), and we found that these vectors induced apoptosis but not cell cycle arrest. In a subcutaneous tumor model using nude mice, transfected MIA PaCa-2 cells, stably expressing siRNAs, barely formed tumors compared to control (P<0.05). This study thus demonstrates the usefulness of siRNA expression vector in targeting HIF1alpha and points to a potential clinical role in the treatment of pancreatic and hepatobiliary carcinomas.     

siRNA抑制卵巢癌细胞株SKOV3 HPA基因表达的研究

目的: 〖HT5"SS〗研究siRNA对卵巢癌细胞株SKOV3中乙酰肝素酶(heparanase,HPA)基因表达的抑制作用。〖HT5W〗方法: 〖HT5"SS〗设计合成两对HPA编码基因的反向重复序列,中间间隔9个核苷酸序列,通过定向克隆至载体PGenesil1,构建siRNA真核表达载体,经稳定转染SKOV3细胞后应用RTPCR、realtime PCR及免疫组化技术检测卵巢癌细胞中HPA基因mRNA及蛋白表达水平的抑制情况。〖HT5W〗结果: 〖HT5"SS〗测序证实成功地构建了编码2条shRNA的siRNA真核表达载体。通过RTPCR、realtime PCR及免疫组化技术检测转染siRNA的SKOV3细胞,与对照组相比,HPA mRNA表达水平和蛋白表达水平明显降低。〖HT5W〗结论:〖HT5"SS〗构建的PGenesil1(+)HPA重组质粒能有效的抑制HPA基因在卵巢癌细胞株SKOV3中的表达,为研究HPA基因在肿瘤细胞中的调节途径和肿瘤的基因治疗提供了新的方法。     

靶向VEGF基因的siRNA体外抑制兔VX2细胞生长的研究

目的:探讨靶向VEGF基因的siRNA对兔VX2肿瘤细胞生长的影响。方法:采用化学合成法得到靶向兔VX2细胞VEGF基因的siRNA分子,应用脂质体将其转染体外培养的VX2细胞。转染48h后,RT-PCR法检测VEGF mRNA水平,ELISA法检测细胞分泌的VEGF蛋白,MTT法检测细胞生长活力。结果:VEGF-si1和VEGF-si3单独转染VX2细胞,细胞的生长抑制率分别为（38.5±7.3）%和（30.0±5.8）%,均显著高于scr-siRNA转染的对照组（P<0.01）;细胞VEGF mRNA表达水平分别为（0.37±0.06）和（0.45±0.07）,均显著低于对照组（P<0.01）;细胞分泌VEGF蛋白的抑制率分别为（58.1±7.3）%和（51.9±7.9）%,均显著高于对照组（P<0.01）。结论:VEGF siRNA分子在体外能特异地抑制兔VX2细胞的VEGF基因mRNA转录,VEGF蛋白分泌以及细胞增殖。     

利用siRNA抑制食管癌VEGF-C的表达

目的 利用siRNA抑制人食管癌EC9706细胞中VEGF-C基因的表达。方法 针对VEGF-C mRNA设计了3条siRNA,并构建相应的表达质粒,将质粒转染食管癌EC9706细胞,筛选稳定表达株,利用RT-PCR和原位杂交技术分析siRNA对细胞中VEGF-C mRNA的降解作用;免疫组织化学法分析细胞中VEGF-C蛋白的表达;利用裸鼠进行体内成瘤性实验,免疫组织化学法检测瘤组织中VEGF-C的表达。结果 siRNA能明显降低食管癌EC9706细胞中VEGF-C mRNA和蛋白的表达,稳定转染的3个siRNA组细胞仅有少量VEGF-C阳性表达颗粒和无阳性条带,与无关序列组和正常EC9706细胞组相比,差异均有统计学意义（P<0.01）;裸鼠体内的成瘤实验,3个siRNA转染组瘤组织中VEGF-C蛋白的表达也明显减少,与正常EC9706组无关序列组相比,差异均有统计学意义（P<0.01）。结论 靶向VEGF-C mRNA的siRNA能在体内外有效抑制VEGF-C的表达,可用于食管癌的基因治疗。     

An <Emphasis Type="Italic">in vitro</Emphasis> Study on the Suppressive Effect of Glioma Cell Growth Induced by Plasmid-Based Small Interference RNA (siRNA) Targeting Human Epidermal Growth Factor Receptor

Summary Objectives:To study the inhibitory effects of plasmid-based siRNA targeting human epidermal growth factor receptor (EGFR) on tumor proliferation and invasion of TJ905 glioblastoma cells. Methods: Two siRNA expression constructs targeting human EGFR extracellular domain (516–536) and catalytic domain (2400–2420) were transfected into TJ905 cell as mediated by Lipofectamine. Immunofluorescence assay and Western blotting were used to detect EGFR expression. Cell cycle was analyzed by flow cytometry, cell proliferative activity was measured by MTT assay. The expression and enzymatic activity of MMP9 were measured by Western blotting and gelatin zymography. Cell invasive capability was evaluated by Transwell method. Results: The expression of EGFR was knocked-down by 90 and 92, respectively in siRNA constructs transfected groups as indicated by immunofluorescence assay and Western blotting. The flow cytometric analysis showed that the S phase fraction (SPF) was lowered in both siRNAs transfected cells than that in parental cells and the cells transfected with empty vector. Compared to parental cells and the cells transfected with empty vector, the survival rates of glioma cells transfected with the siRNAs dramatically dropped down from the first day after implantation (P<0.05) as indicated by MTT assay. Meanwhile, the expression and enzymatic activity of MMP9 decreased significantly in siRNAs transfected in TJ905 cells, and cell invasive potential was also greatly inhibited in the Transwell study. Conclusion: The siRNA expression constructs targeting EGFR could specifically suppress EGFR expression, inhibit cell growth, induce cell cycle arrest and suppress invasion. The plasmid-based siRNA targeting human EGFR approach should be a new strategy for gene therapy of malignant gliomas.     

TFPI-2基因克隆及其在胰腺癌细胞中的表达

目的克隆人TFPI-2基因全长cDNA,构建其真核表达载体,并将其转染到人胰腺癌细胞Panc-1中,检测其表达。方法用RT-PCR法从人胎盘组织中扩增人TFPI-2基因,并将其与真核表达载体pEGFP-C1连接,构建真核表达载体pEGFP-C1-TFPI-2。将构建的重组载体转染到人胰腺癌细胞系Panc-1细胞,Westernblot检测TFPI-2在Pane-1细胞中的表达。结果RT-PCR成功的扩增出一条约708bp的片断,扩增片断与载体连接后,经限制性内切酶酶切电泳分析和DNA序列测定证实该基因已经成功构建到载体上,转染Panc-1细胞后,荧光显微镜观察到稳定转染细胞发出较强绿色荧光,Westernblot技术证明TFPI-2基因能在Panc-1细胞中稳定表达。结论成功构建了人TFPI-2基因的真核表达载体pEGFP-C1-TFPI-2,获得了稳定表达TFPI-2的Panc-1细胞,证实TFPI-2基因能够在人胰腺癌细胞系Panc-1中高效、稳定的表达,为进一步研究其胰腺癌迁移、浸润及转移中的作用打下基础。     

RNA干扰技术沉默STAT3 对人肺癌细胞生长抑制的作用

 目的 探讨RNA干扰技术沉默STAT3基因表达对肺腺癌A549细胞的生长抑制作用。方法针对STAT3mRNA序列设计合成2对编码si RNA的DNA模板,构建pSUPER-si RNA-STAT3重组质粒,转染A549细胞;采用RT-PCR法检测重组质粒对STAT3基因表达的影响;在荧光显微镜下观察细胞的凋亡情况。结果 成功构建pSUPER-si RNA-STAT3重组质粒,并成功转染A549细胞。特异性si RNA片段能有效降低STAT3mRNA水平,最大干扰效率达85.32%,明显高于空质粒对照组;干扰作用于转染后24h即可出现,48h达高峰,72h降低。对应不同位点的两个si RNA片段对STAT3均可产生干扰作用,彼此间差别不大。在荧光显微镜下,与未转染细胞相比,转染si RNA的A549细胞中凋亡细胞所占比例明显增加。结论 pSUPER-si RNA-STAT3可抑制STAT3在人肺腺癌A549细胞中的表达,并抑制肿瘤细胞的生长,促进其凋亡。以STAT3为靶点的RNA干扰技术可望成为肺癌基因治疗的新方法。     

体内阻断胰腺癌细胞FasL表达抑制肿瘤细胞免疫反击的初步研究

目的:探讨体内抑制胰腺癌细胞表面的FasL表达,能否抑制胰腺癌细胞对免疫系统的反击作用。方法:反义核酸技术扩增C57BL/6小鼠FasL mRNA 35~371位点核苷酸序列互补的cDNA片断,构建pBlast质粒后,转染人Panc-1胰腺癌细胞株,蛋白质印迹观察细胞株FasL蛋白表达的变化,ELISA法检测培养上清可溶性FasL水平。将细胞注射到C57BL/6小鼠胰腺包膜下,观测瘤体的直径变化,免疫组化观测肿瘤组织内浸润淋巴细胞的数量。结果:在稳定转染编码反义FasL cDNA的质粒后,胰腺癌细胞表面的FasL表达明显下调;其FasL蛋白表达下降了80%;FasL表达下调对体外生长的胰腺癌细胞无明显影响,但能减少同系免疫活性鼠体内肿瘤的发展。转染了质检DNA的胰腺癌细胞接种组瘤体的平均直径为1.53 mm,而未转染质检DNA的胰腺癌细胞接种组为2.98 mm,两组比较差异有统计学意义,P<0.01。与未来转染组相比,转染组CD45 TIL细胞数量明显增多,是未转染组的3.23倍,P<0.01。结论:胰腺癌细胞表面FasL表达的下调,能在体内增加免疫系统的抗肿瘤能力,从而为"肿瘤反击"促进肿瘤细胞浸润的学说提供了有力的证据。     

RMP基因沉默对肝癌SMMC-7721细胞增殖和迁移能力的影响

目的:建立RMP(RPB5-mediating protein)基因沉默的稳定细胞株,研究RMP小干扰RNA(small interfering RNA, siRNA)对人肝癌SMMC-7721细胞增殖和迁移的抑制作用.方法:首先,体外合成3条RMP基因的siRNA,并转染到SMMC-7721细胞中,RT-PCR检测3条siRNA对RMP基因表达的抑制作用,筛选出最佳干扰序列;然后,pGPU6-Neo-RMP-484真核表达载体转染,G418筛选出稳定干扰RMP基因的细胞株,RT-PCR法检测该稳定细胞株中RMP基因的干扰效率,MTT法检测RMP-siRNA对SMMC-7721细胞增殖及细胞黏附能力的影响,划痕实验检测细胞迁移能力的变化.结果:利用RNA干扰技术成功建立了RMP基因下调的稳定细胞株,与SMMC-7721细胞对照组比较,其RMP mRNA表达水平下调了(83.67±2.56)%.稳定转染siRNA的细胞株细胞增殖受到抑制,增殖抑制率可达(74.33±0.58)%.稳定转染细胞株的细胞黏附能力有所增加,迁移率则相应降低.结论:成功筛选出了稳定转染RMP-siRNA重组载体的细胞株.pGPU6-Neo-RMP-484重组载体能有效抑制RMP基因在肝癌SMMC-7721细胞内的表达,可作为RMP分子机制研究的细胞模型.RMP基因的下调能有效抑制肝癌细胞SMMC-7721的增殖,使其黏附率增加,同时细胞的迁移率降低.     

siRNA沉默多效生长因子表达及其生物学意义

背景与目的:多效生长因子(pleiotrophin,Ptn)基因是一种分泌性的生长因子,具有促进肿瘤细胞的增殖与迁移及肿瘤血管的生成等功能。有研究表明,抑制该基因的表达,就能够有效地控制肿瘤细胞的过度增殖,从而达到抑制肿瘤发生与发展的目的。本研究旨在合成一种能够有效抑制该基因表达的小干扰RNA。方法:(1)设计并合成具有基因特异性的一组寡核苷酸片段,并克隆到pSilencerTM3.1-H1hygro载体;(2)瞬时转染siRNA表达载体至3T3细胞,以检测不同siRNA对Ptn基因表达的抑制能力;(3)用脂质体Lipofectamine2000转染和潮霉素筛选等方法建立能稳定表达相应PtnsiRNAs的一组PTEN-/-MEF241细胞株,并对其Ptn的表达水平进行检测;(4)利用细胞生长曲线检测沉默Ptn基因对PTEN-/-MEF241细胞生长的影响;(5)裸鼠成瘤实验观察Ptn基因沉默后,PTEN-/-MEF241细胞致瘤特性的改变。结果:设计并合成了3条针对Ptn基因的siRNAs,并证实其中的1条小干扰RNA,即PtnsiRNA-B能显著地抑制PTEN-/-MEF241细胞中Ptn基因的表达,抑制效率达到95%以上;同时能使PTEN-/-MEF241的生长速度明显减慢;接种裸鼠后成瘤率仅为1/8,而对照组的成瘤率为5/8,发生肿瘤的潜伏期超过90天,而对照组为30天左右,可见裸鼠成瘤率被显著抑制,发生肿瘤的潜伏期大大延长。结论:本研究设计并合成的针对Ptn基因的小干扰RNA,即PtnsiRNA-B能够抑制PTEN-/-MEF241细胞增殖,降低PTEN-/-MEF241细胞的致瘤性,因此可能成为一种新型的肿瘤基因治疗药物。     

RNA干扰抑制BMP-2基因表达对人肝癌SMMC7721细胞增殖和凋亡的影响

目的：设计并化学合成针对骨形态发生蛋白2（BMP-2）的siRNA分子片段,转染人肝癌SMMC7721细胞,观察其对SMMC7721细胞增殖和凋亡的影响。方法：阳离子脂质体法瞬间转染SMMC7721细胞,半定量逆转录聚合酶链反应(RT-PCR)法和Western印迹法检测转染BMP-2-siRNA后细胞BMP-2 mRNA水平和蛋白水平的变化,MTT法和流式细胞术检测转染BMP-2-siRNA后SMMC7721细胞增殖、细胞周期和凋亡的变化。结果：3对特异性BMP-2-siRNA均有效地抑制了BMP-2基因的表达,以siRNA-B抑制效果最好。转染BMP-2-siRNA后SMMC7721细胞的增殖能力明显受到抑制( P <0.05)且明显促进了SMMC7721细胞的凋亡。结论：靶向BMP-2基因的siRNA分子片段可以有效地抑制人肝癌SMMC7721细胞的增殖并促进其凋亡     

Overexpression of neuropilin-1 promotes constitutive MAPK signalling and chemoresistance in pancreatic cancer cells

Neuropilin-1 (NRP-1) is a novel co-receptor for vascular endothelial growth factor (VEGF). Neuropilin-1 is expressed in pancreatic cancer, but not in nonmalignant pancreatic tissue. We hypothesised that NRP-1 expression by pancreatic cancer cells contributes to the malignant phenotype. To determine the role of NRP-1 in pancreatic cancer, NRP-1 was stably transfected into the human pancreatic cancer cell line FG. Signal transduction was assessed by Western blot analysis. Susceptibility to anoikis (detachment induced apoptosis) was evaluated by colony formation after growth in suspension. Chemosensitivity to gemcitabine or 5-fluorouracil (5-FU) was assessed by MTT assay in pancreatic cancer cells following NRP-1 overexpression or siRNA-induced downregulation of NRP-1. Differential expression of apoptosis-related genes was determined by gene array and further evaluated by Western blot analysis. Neuropilin-1 overexpression increased constitutive mitogen activated protein kinase (MAPK) signalling, possibly via an autocrine loop. Neuropilin-1 overexpression in FG cells enhanced anoikis resistance and increased survival of cells by > 30% after exposure to clinically relevant levels of gemcitabine and 5-FU. In contrast, downregulation of NRP-1 expression in Panc-1 cells markedly increased chemosensitivity, inducing > 50% more cell death at clinically relevant concentrations of gemcitabine. Neuropilin-1 overexpression also increased expression of the antiapoptotic regulator, MCL-1. Neuropilin-1 overexpression in pancreatic cancer cell lines is associated with (a) increased constitutive MAPK signalling, (b) inhibition of anoikis, and (c) chemoresistance. Targeting NRP-1 in pancreatic cancer cells may downregulate survival signalling pathways and increase sensitivity to chemotherapy.     

EphB4 regulates the growth and migration of pancreatic cancer cells

Pancreatic cancer is a serious threat to human life. Moreover, its treatment is complicated and its prognosis is very poor. Therefore, a new method for the diagnosis and treatment of pancreatic cancer is very essential. In this study, a eukaryotic expression plasmid targeting EphB4 was constructed and transfected into PANC-1 pancreatic cancer cells to investigate the inhibition of cell growth and the progression of iRNA against EphB4. This study provides the basis for the gene therapy of pancreatic cancer. The recombinant eukaryotic EphB4 expression plasmid, pSIREN-RetroQ-ZsGreen-EphB4 and a negative control plasmid, pSIREN-RetroQ-ZsGreen-N, were constructed. At 48 h after transfection, the relative messenger RNA (mRNA) and protein levels of EphB4 were measured by RT-PCR and western blot. The proliferation of the transfected cells was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, while cell migration ability was analyzed using the scratch migration assay. At 48 h after transient transfection, EphB4 mRNA expression was significantly decreased in transfected PANC-1 cells as compared to the control group (P?<?0.01). In vitro, inhibition of EphB4 expression weakened the proliferation and cell migration ability of PANC-1 cells compared to the control group. The small interfering RNA (siRNA) eukaryotic expression plasmid vector targeting EphB4 was successfully constructed and effectively transfected into PANC-1 cells. The recombinant plasmid can inhibit the expression of EphB4 mRNA and protein in PANC-1 cells, as well as cell growth and migration.     

Knockdown of Ezrin by RNA Interference Reverses Malignant Behavior of Human Pancreatic Cancer Cells in Vitro

Background: Pancreatic cancer is one of the most aggressive tumors with a dismal prognosis. The membranecytoskeletal crosslinker Ezrin participates in several functions including cell proliferation, adhesion, motilityand survival. There is increasing evidence that Ezrin is overexpressed in vast majority of malignant tumorsand regulates tumor progression. However, its roles in pancreatic cancer remain elusive. Methods: Three pairsof specific Ezrin siRNAs were designed and synthetized and screened to determine the most efficient one forconstruction of a hairpin RNA plasmid targeting Ezrin. After transfection into the Panc-1 pancreatic cancer cellline, real-time quantitative PCR and Western blotting were performed to examine the expression of mRNA andprotein. The MTT method was applied to examine the proliferation and the drug sensibility to Gemcitabine.Flow cytometry was used to assess the cycle and apoptosis, while capacity for invasion was determined withtranswell chambers. Furthermore, we detected phosphorylated-Erk1/2 protein and phosphorylated-Akt proteinby Western blotting. Results: Real-time quantitative PCR and Western blotting revealed that Ezrin expressionwas notably down-regulated at both mRNA and protein levels by RNA interference (P< 0.01). Proliferationwas inhibited and drug resistance to gemcitabine was improved (P< 0.05). Flow cytometry showed that theproportion of cells in the G1/G0 phase increased (P< 0.01), and in G2/M and S phases decreased (P< 0.05), withno apparent differences in apoptosis (P> 0.05). The capacity for invasion was markedly reduced (P< 0.01). Inaddition, down-regulating Ezrin expression had no effect on phosphorylated-Akt protein (P>0.05), but coulddecrease the level of phosphorylated-Erk1/2 protein (P< 0.05). Conclusions: RNA interference of Ezrin couldinhibit its expression in the pancreatic cancer cells line Panc-1, leading to a potent suppression of malignantbehavior in vitro. Assessment of potential as a target for pancreatic cancer treatment is clearly warranted.     

突变型K-ras siRNA抑制肺癌A549细胞的增殖和迁移并诱导细胞凋亡

目的:构建靶向Kras的siRNA,研究Kras siRNA对Kras基因突变型肺癌细胞A549及Kras野生型小细胞肺癌细胞NCIH446生长和迁移的抑制作用。方法:设计并人工合成4条Kras siRNA（针对野生型Kras基因的Kras siRNA1~ Kras siRNA3;针对突变型Kras 基因的Kras siRNA4）,并分别转入A549和NCIH446细胞。RTPCR和Western blotting检测不同Kras siRNA对Kras mRNA和蛋白表达的影响,MTT法检测不同Kras siRNA对A549和NCIH446细胞增殖的抑制作用,Transwell实验和Hoechst 33258染色检测Kras siRNA对细胞迁移和凋亡的影响。结果:靶向突变型Kras的Kras siRNA4能特异性抑制A549细胞中Kras的表达,但对Nras和Hras的表达没有影响。Kras siRNA4抑制A549细胞的增殖,但不影响含野生型Kras基因的NCIH446细胞的增殖。Kras siRNA4还能诱导A549细胞凋亡、抑制A549细胞迁移。结论: 针对突变型Kras基因的siRNA可特异性抑制Kras突变型肺癌细胞的增殖和迁移,并诱导该细胞凋亡,Kras siRNA可望用于Kras突变型肿瘤特别是肺癌的个体化治疗。     

小分子干扰RNA特异性抑制人胰腺癌细胞株PANC-1突变型K-ras基因表达的探讨

目的:研究小分子干扰RNA(small interfering RNA,siRNA)对人胰腺癌细胞株PANC-1中突变型K-ras基因表达的抑制作用.方法:构建真核表达载体pSilencer3.1-K-rasv12,转染PANC-1细胞后应用RT-PCR及Western blot检测突变型K-ras基因mRNA及蛋白质表达变化;噻唑蓝(MTT)测定细胞生长曲线;流式细胞仪测定细胞凋亡率.结果:测序证实siRNA真核表达载体构建成功.RT-PCR光密度比值结果空载体组、阴性对照组、实验组分别为:95.3%±2.5%、97.6%±2.8%、40.1%±3.1%,差异有统计学意义(P＜0.05);Western blot灰度比值结果空载体组、阴性对照组、实验组分别为:96.1%±2.2%、98.5%±2.0%、36.5%±3.2%,差异有统计学意义(P＜0.05);实验组细胞生长受到明显抑制,凋亡率较对照组明显升高(P＜0.05).结论:pSilencer3.1-K-rasv12能有效抑制突变型K-ras基因在人胰腺癌细胞株PANC-1中的表达,抑制细胞生长,诱导细胞凋亡,为肿瘤的生物学治疗提供了新的方法.