携多药耐药基因1反义RNA重组腺病毒逆转肝癌多药耐药细胞的实验研究

目的探讨携带多药耐药基因1(multidrug resistance gene 1,MDR1)反义RNA重组腺病毒载体在裸鼠体内逆转肝癌多药耐药细胞HepG2/阿霉素(adriamycin,ADM)的疗效及作用机制。方法构建携带AFP和asmdr1的重组腺病毒载体Adeno-asmdr1,ADM分级诱导肝癌细胞HepG2为多药耐药细胞HepG2/ADM,建立HepG2/ADM裸鼠皮下移植瘤模型,Adeno asmdr1局部注射,观察移植瘤的体积、透射电镜检测移植瘤组织细胞凋亡、RT-PCR检测MDR1转录水平,评价Adeno-asmdr1的抗肿瘤活性。结果在Adeno-asmdr1 ADM组,移植瘤体积无增大,而PBS组、ADM组体积明显增大;RT-PCR检测移植瘤细胞1周和4周MDR1 mRNA水平, ADM组无明显变化,Adeno-amdr1 ADM组在4周时MDR1转录水平仅为单纯ADM组的20%,经ADM Adeno-asmdr1处理组,可见凋亡增加,ADM组和PBS处理组的裸鼠移植瘤组织中出现少量或没有凋亡。结论携带MDR1反义RNA重组腺病毒部分逆转HepG2/ADM的多药耐药,阻止肿瘤生长,下调MDR1转录水平,导致肿瘤细胞凋亡。     

胰岛素抵抗肝细胞多药耐药基因1的表达

目的体外观察诱导发生胰岛素抵抗（IR）肝细胞中多药耐药基因1（mdr1）的表达。方法采用高浓度胰岛素诱导肝源性细胞HepG2建立IR细胞模型（HepG2/IR细胞）,GOD-POD微量化法测定葡萄糖消耗量,RT-PCR检测HepG2/IR细胞mdr1和胰岛素受体（InsR）基因mRNA的表达,流式细胞术检测P糖蛋白（P-gp）和InsR蛋白水平。结果HepG2/IR细胞葡萄糖消耗量降低10%～45%,InsR基因mRNA表达显著下调,受体表达量降低50.2%～82.9%;mdr1表达显著增强,mRNA转录增高0.7～2.1倍,P-gp表达阳性细胞增加0.6～1.7倍,表达强度增高。结论IR肝细胞mdr1和P-gp的表达显著增强。     

重组腺病毒介导反义2型基质金属蛋白酶抑制人肝癌细胞株浸润的实验研究

目的构建携带反义2型基质金属蛋白酶(MMP2)的重组腺病毒并探讨它对人肝癌细胞株HepG2侵袭细胞基底膜的抑制作用。方法从新鲜肝癌组织中提取总RNA,用逆转录聚合酶链反应法合成MMP2cDNA序列中5'端转录起始位点附近长约500bp的基因片段,将此片段反义克隆到腺病毒载体系统的多克隆位点,经转染293细胞包装生成携带反义MMP2基因的重组腺病毒Ad-MMP2AS;利用侵袭小室模型,检测Ad-MMP2AS对肝癌细胞株(HepG2细胞)体外侵袭能力的影响。结果成功构建并生成携带反义MMP2基因片段的重组腺病毒Ad-MMP2AS,病毒滴度达1×108;体外细胞实验中Ad-MMP2AS能明显抑制HepG2细胞穿透人工重组基底膜的能力。结论重组腺病毒介导反义MMP2基因可望有效抑制肝癌细胞的浸润和转移,为肝细胞癌的基因治疗提供新的方法。     

可溶性肿瘤坏死因子相关凋亡诱导配体重组腺病毒载体的构建及其在肝癌细胞株中的表达

肿瘤坏死因子相关凋亡诱导配体（TRAIL）能诱导30余种人类肿瘤细胞凋亡，在抗肿瘤治疗中具有广阔应用前景。目的：构建携带可溶性TRAIL基因的复制缺陷型重组腺病毒载体，鉴定其在肝癌细胞株中的表达。方法：以重叠延伸聚合酶链反应（PCR）扩增白细胞介素（IL）-2信号肽和TRAIL膜外区融合片段，克隆于腺病毒穿梭质粒pAdTrack—CMV，转化含复制缺陷型腺病毒骨架质粒pAdEasy-1的大肠杆菌pAdBJ5183，经细菌内同源重组产生重组腺病毒Ad-IL-2-TRAIL，以脂质体法转染HEK293细胞包装病毒，感染肝癌细胞株HepG2．荧光显微镜下观察增强型绿色荧光蛋白（EGFP）的表达。结果：成功构建了携带可溶性TRAIL基因的复制缺陷型重组腺病毒载体。病毒感染HepG2细胞48h后，超过95％的细胞中出现绿色荧光。结论：所构建的复制缺陷型重组腺病毒Ad—IL-2-TRAIL可在肝癌细胞中高效表达可溶性TRAIL，为进一步行肿瘤TRAIL基因冶疗提供了实验依据。     

反义寡核苷酸并超声微泡造影剂转染联合超声照射逆转肝癌多药耐药

目的探讨体内、体外mdr1、mrp、lrp反义寡核苷酸(AODNs)并超声微泡造影剂转染联合低强度超声照射逆转肝癌多药耐药的可行性,寻找逆转肿瘤多药耐药有效和靶向的方法。方法利用超声微泡造影剂包载肿瘤耐药基因mdr1、mrp、lrp的AODNs进行转染,联合低强度超声照射,以肝癌细胞多药耐药细胞模型(HepG2／ADM) 为研究对象,通过逆转录聚合酶链反应、western blot和四甲基偶氮唑盐法,从体外细胞培养及动物实验,研究 AODNs并超声微泡造影剂转染联合超声照射逆转癌细胞多药耐药及降低肿瘤恶性表型和成瘤能力的作用。结果 HepG2／AMD细胞增殖被抑制,其mdr1和mrp的mRNA、蛋白质表达水平明显降低;裸鼠皮下移植瘤生长受抑制。结论体外、体内AODNs并超声微泡造影剂转染联合低强度超声照射能有效逆转人肝癌细胞HepG2／ADM的多药耐药, 该技术可能为肝癌临床治疗提供新的思路。     

胰岛素抵抗肝癌细胞IGF-1R/NF-κB表达及多药耐药机制研究

目的 探讨胰岛素抵抗（IR）肝癌细胞胰岛素样生长因子1受体（IGF-1R）和核因子-κB（NF-κB）表达变化及多药耐药（MDR）发生机制。方法 采用高浓度胰岛素诱导人肝癌细胞（HepG2和HepG2.2.15）建立胰岛素抵抗（IR）细胞模型。采用Western blot 法检测胰岛素受体（InsR）、IGF-1R、NF-κB 和 P-糖蛋白（P-gp）表达变化。使用流式细胞仪（Annexin V-FITC法）检测阿霉素对细胞凋亡的影响。结果 分别用100 nmol/L 和 1 000 nmol/L 胰岛素培养 HepG2 和 HepG2.2.15 细胞 48 h,成功建立 IR 肝癌细胞模型;IR 肝癌细胞 IGF-1R、NF-κB、P-gp 表达上调,而InsR 表达下调;应用 25μg/mL 阿霉素作用细胞 24 h 后,IR-HepG2 细胞组凋亡率（31.1%±1.9%）显著低于HepG2 细胞组【（49.7%±2.2%）,P＜0.01】,IR-HepG2.2.15细胞凋亡率【（20.1±1.7） %】显著低于 HepG2.2.15 细胞【（33.8±1.8）%,P＜0.01】;HepG2.2.15 和 IR-HepG2.2.15 细胞凋亡率分别较 HepG2 和 IR-HepG2 细胞显著降低（P＜0.01）。结论 IGF-1R/NF-κB/P-gp 过表达可能介导 IR 肝癌细胞对阿霉素的多药耐药。     

靶向多药耐药基因mdr1 RNA干扰载体的构建及鉴定

目的 构建靶向人多药耐药基因mdr1的microRNA(miRNA)干扰表达载体并进行鉴定. 方法 设计并合成4对编码mdr1 pre-miRNA的单链寡核苷酸,退火成双链后将其连接入miRNA干扰载体pcDNA6.2-GW/EmGFP-miR,构建成重组质粒,酶切并测序鉴定其正确性. 结果 获得的重组质粒经酶切测序证实其插入片段大小与预期相符,序列完全正确. 结论 成功构建了4个靶向mdr1的miRNA干扰载体.     

携带AFP增强子反义c-fms真核表达载体的构建及其临床意义

目的 构建人肝癌细胞中高效特异表达的反义c-fms真核表达载体,观察其对肝癌细胞生物学行为的影响。方法 采用PCR法扩增人c-fms癌基因第571位酪氨酸为中心的DNA片段,将其反向克隆人pcDNA3载体（命名pAS);将扩增的人甲胎蛋白（AFP）增强子核心区克隆人pAS（命名pAEAS)。磷酸钙法将空载体pcDNA3及反义真核表达载体pAS、pAEAS分别转导入HepG2肝癌细胞及HeLa宫颈癌细胞,观察细胞生长速度及凋亡。结果 人反义c-fms基因片段及AFP增强子核心区片段,测序结果与Genbank中登录的序列一致。导入反义基因的HepG2肝癌细胞生长速度较对照细胞明显减慢（P＜0．05）,pAEAS抑制作用较pAS强（P＜0．05,pcDNA3组、pAS组、pAEAS组HepG2肝癌细胞凋亡率分别为5．25％、14．7％、31．2％（P＜0．01）,pAEAS组细胞DNA出现梯状凋亡带。在HeLa宫颈癌细胞中,pAS及pAEAS组生长速度减慢,但二者差异无显著性（P＞0．05）,pcDNA3组、pAS组、pAEAS组细胞凋亡率分别为3．99％、8．27％、8．86％（P＜0．05）,DNA均未出现梯状凋亡带。结论 携带AFP增强子的人反义c-fms真核表达载体对AFP阳性肝癌细胞生长有选择性抑制作用,可诱导凋亡,是一种新的肝癌基因治疗方法。     

多药耐药相关蛋白-3表达与肝癌耐药的相关性

目的 探讨多药耐药相关蛋白-3(MRP-3)的表达与肝癌耐药的相关性.方法 应用RT-PCR方法检测正常肝细胞L-02、肝癌细胞BEL及肝癌耐药细胞HepG2/ADM中MRP-3 mRNA的差异表达,再将MRP-3反义及正义寡核苷酸片段分别用脂质体转染进肝癌耐药细胞HepG2/ADM中,用MTT法、流式细胞仪及RT-PCR检测转染后细胞内阿霉素(ADM)的荧光强度、耐药指数及MRP-3 mRNA的表达情况.结果 肝癌耐药细胞HepG2/ADM中MRP-3 mRNA的表达明显高于正常肝细胞L-02和肝癌细胞BEL(P<0.05).MRP-3反义转染进耐药细胞后,可明显降低细胞内ADM的耐药指数,提高细胞内ADM浓度(P<0.05),细胞内MRP-3 mRNA的表达较未转染细胞下降了62.5%(P<0.05).结论 MRP-3的高表达可能是导致肝癌多药耐药的机制之一.     

siRNA腺病毒抑制Survivin基因表达诱导肝癌细胞凋亡

目的为改进质粒siRNA载体的不足,建立siRNA的病毒性载体系统,并探讨凋亡抑制因子Survivin基因在肝癌细胞中的作用。方法通过已建立的Survivin质粒siRNA,构建Survivin的腺病毒siRNA载体系统,筛选重组病毒并感染肝癌细胞HepG2细胞,应用Western blot和RT-PCR检测Survivin基因表达变化,用流式细胞仪观察肿瘤细胞凋亡。结果成功构建Survivin基因的腺病毒siRNA载体及重组腺病毒,感染肝癌细胞明显抑制Survivin蛋白表达,抑制率66.32%;降低Survivin基因的mRNA转录水平达72.04%;应用流式细胞仪观察肿瘤细胞凋亡明显增加。结论腺病毒siRNA载体系统可作为抑制目的基因,进而研究其功能和作用的技术平台,并为其他基因的相关研究打下基础;抑制Survivin基因表达可诱导肿瘤细胞HepG2的凋亡,为今后腺病毒siRNA载体应用于肿瘤动物实验和肿瘤基因治疗提供实验资料。     

Overcoming multi-drug resistance by anti-MDR1 ribozyme

AIM: To reverse multidrug resistance (MDR) of HepG2 by anti-MDR1 hammerhead ribozyme. METHODS: We developed an anti-MDR1 hammerhead ribozyme and delivered it to P-gp-overproducing human hepatocarcinoma cell line HepG2 by a retroviral vector containing RNA polymerase III promoter. We detected the expression of mdr1/Pgp and Rz in HepG2, HepG2 multidrug-resistant cell line and HepG2 Rz-transfected cells by real-time RT-PCR, semi-quantitative RT-PCR and Western blot methods. Moreover, MTT assay was tested to detect sensitivity of these ribozyme-transfected cells, and Rhodamine123 (Rh123) applied to test the function of Pgp. RESULTS: The Rz- transfected HepG2 cells became doxorubicin-sensitive, concomitant with the decreases in MDR1 expression, P-gp amounts and efflux pump function. CONCLUSION: The approaches using either retrovirus or liposome-mediated transfer of anti-MDR1 ribozyme may be selectively applicable to the treatment of MDR cells.     

Subcellular daunorubicin distribution and its relation to multidrug resistance phenotype in drug—resistant cell line SMMC—7721／R

AIM：To investigate the correlation between subcellular daunorubicin distribution and the multidrug resistance phenotype in drug-resistant cell line SMMC-7721/R.METHODS:The multidrug resistant cell line SMMC-7721/R,a human hepatocellular carcinoma cell line,was established.Antisenes oligonucleotides(AS-ODN)were used to obtain different multidrug resistance phenotypes by inhibiting the expression of mdr1 gene and/or multidrug resistance-related protein gene(mrp)using Lipofectamine as delivery agent.Expression of mdr1 and mrp genes was evaluated by RT-PCRand Western blotting.Intracellular daunorubicn(DNR)concentration was measured by flow cytometry.Subcellular DNR distribution was analyzed by confocal laser scanning microscopy.Adriamycin(ADM)and DNR sensitivity was examined by MTTmethod.RESULTS:Low level expression of mdr1 and mrpmRNAs and no expression of P-Glycoprotein(P-gp)and multidrug resistance-related protein(P190)were detected in parental sensitive cells SMMC-7721/S,but over-expression of these two genes was observed in drug-resistant cell SMMC-7721/R,The expression of mdr1 and mrp genes in SMMC-7721/Rcells was down-regulated to the level in the SMMC-7721/Scells by AS-ODN.Intracellular DNAconcentration in SMMC-7721/Scells was 10times higher than that in SMMC-7721/Rcells.In SMMC7721/Scells intracellular DNA distributed evenly in the nucleus and cytoplasm.while in SMMC-7721/Rcells DNR distributed in a punctate pattern in the cytoplasm and was reduced in the nucleus.DNR concentration in SMMC-7721/Rcells co-transfected with AS-ODNs targeting to mdr1and rpmRNAs recovered to 25percent of that in SMMC7721/Scells.Intracellular DNA distribution pattern in drug-resistant cells treated by AS-ODN was similar to drug-sensitive cell.and the cells resistance index(RI)to DNA and AMD decreased at most from 88.0and 116.0to4.0and 2.3,repectively.Co-Transfection of two AS-ODNs showed a stronger synergistic effect than separate transfection.CONCLUSIONS:P-gp and P190are two members mediatingMDR in cellline SMMC7721/R,Intracellular drug concentration increase and subcellular distribution change are two important factos in multidrug resistance(MDR)formation.The second facto,drugs transport by P-gp andP190from cell nucleus to organell in cytoplasm,may play a more important role.     

Reversal of multi-drug resistance by pSUPER-shRNA-mdr1 in vivo and in vitro

AIM： To explore the possibility of reversing multi-drug resistance （MDR） to HepG2/mdr1 in vitro and in vivo with RNA interference （RNAi）. METHODS： HepG2/mdr1 was obtained by cloning the whole gene mdrl into HepG2 cells, shRNA targeting sequence was designed to be homologous to the P-gp encoding MDR1 mRNA consensus sequence, pSUPER- shRNA/mdrl was constructed using the enzyme- digested technique. HepG2/mdrl cells were transfected with vectors of pSUPER-shRNA/mdrl to measure their efficacy by real-time PCR for mdrl mRNA, flow cytometry （FCM） for P-gp expression, and Rhodamine efflux, MTT method for HepG2/mdrl function, respectively. In vivo, mice tumors were treated by injecting pSUPER-shRNA/mdrl in situ and into intra- abdominal cavity. Tumors were collected to create cell suspension and cryosections after chemothearpy with adiramycin and mytomycin. The cell suspension was incubated in RPMI-1640 supplemented with G418 to screen stable cells for appreciating the reversal of MDR. Cryosections were treated with immunohistochemistry technique to show the effectiveness of transfection and the expression of P-gp.RESULTS： pSUPER-shRNA/mdrl was successfully constructed, which was confirmed by sequencing. The MDR phenotype of HepG2/mdr1 was decreased significantly in vitro transfection. HepG2/mdr1 showing its MDR was reversed notably in P-gp expression （11.0% vs 98.2%, P 〈 0.01）. Real-time PCR showed that mRNA/mdrl was lower in test groups than in control groups （18.73± 1.33 vs 68.03±2.21, P 〈 0.001）. Compared with HepG2, the sensitivity of HepG2/ mdrl and HepG2/mdr1-dsRNA cells to ADM was decreased by 1.64 times and 15.6 times, respectively. The accumulation of DNR in positive groups was decreased evidently. In vivo, the p-gp expression in positive groups was significantly lower than that in control groups （65.1% vs 94.1%, P 〈 0.05）. The tumor suppressing rate in test groups was 57.8%. After chemotherapy, the growth rate in test groups was lower than that in control groups （700.14 ± 35.61 vs 1659.70 ± 152.54, P 〈 0.05）. Similar results were also observed under fluorescence microscope, and confirmed by Image-Pro Plus 4.5 analysis. CONCLUSION： pSUPER-shRNA/mdrl vector system allows simple, stable and durable nonviral knockdown of P-gp by RNAi in malignant cells and animals to restore their sensitivity to adriamycin.     

Construction of a targeting adenoviral vector carrying AFP promoter for expressing EGFP gene in AFP-producing hepatocarcinoma cell

AIM:To construct a recombinant adenoviral vector carrying AFP promoter and EGFP gene for specific expression of EGFP gene in AFP producing hepatocellular carcinoma (HCC) HepG2 cells.METHODS: Based on the Adeno-X^TM expression system, the human immediate early cytomegalovirus promoter (PCMV IE)was removed from the plasmid, pshuttle,and replaced by a 0.3 kb (α-fetoprotein (AFP) promoter that was synthesized by polymerase chain reaction (PCR).The enhanced green fluorescent protein (EGFP) gene was inserted into the multiclone site (MCS),and then the recombinant adenovirus vector carrying the 0.3kb AFP promoter and EGFP gene was constructed.Cells of a normal liver cell line (LO2),a hepatocarcinoma cell line (HepG2) and a cervical cancer cell line (HeLa) were transfected with the adenovirus.Northern blot and fluorescence microscopy were used to detect the expression of the EGFP gene at mRNA or protein level in three different cell lines.RESULTS:The 0.3kb AFP promoter was synthesized through PCR from the human genome.The AFP promoter and EGFP gene were directly inserted into the plasmid pshuttle as confirmed by restriction digestion and DNA sequencing.Northern blot showed that EGFP gene was markedly transcribed in HepG2 cells,but only slightly in LO2 and HeLa cells.In addition,strong green fluorescence was observed in HepG2 cells under a fluorescence microscopy,but fluorescence was very weak in LO2 and HeLa cells.CONCLUSION:Under control of the 0.3kb human AFP promoter, the recombinant adenovirus vector carrying EGFP gene can be specially expressed in AFP-producing HepG2 cells,Therefore,this adenovirus system can be used as a novel,potent and specific tool for gene-targeting therapy for the AFP positive primary hepatocellular carcinoma,     

Construction of a targeting adenoviral vector carrying AFP promoter for expressing EGFP gene in AFP-producing hepatocarcinoma cell

AIM:To construct a recombinant adenoviral vector carryingAFPpromoter and EGFPgene for specific expression of EGFPgene in AFP producing hepatocellular carcinoma (HCC)HepG2 cells.METHODS:Based on the Adeno-X~(TM) expression system,thehuman immediate early cytomegalovirus promoter (P_(CMVIE))was removed from the plasmid,pshuttle,and replaced by a0.3 kb α-fetoprotein (AFP) promoter that was synthesizedby polymerase chain reaction (PCR).The enhanced greenfluorescent protein (EGFP) gene was inserted into the multi-clone site (MCS),and then the recombinant adenovirusvector carrying the 0.3 kb AFP promoter and EGFP genewas constructed.Cells of a normal liver cell line (LO2),ahepatocarcinoma cell line (HepG2) and a cervical cancercell line (HeLa) were transfectecl with the adenovirus.Northern blot and fluorescence microscopy were used todetect the expression of the EGFPgene at mRNA or proteinlevel in three different cell lines.RESULTS:The 0.3 kb AFP promoter was synthesizedthrough PCR from the human genome.The AFP promoterand EGFP gene were directly inserted into the plasmidpshuttle as confirmed by restriction digestion and DNAsequencing.Northern blot showed that EGFP gene wasmarkedly transcribed in HepG2 cells,but only slightly in LO2and HeLa cells.In addition,strong green fluorescence wasobserved in HepG2 cells under a fluorescence microscopy,but fluorescence was very weak in LO2 and HeLa cells.CONCLUSION:Under control of the 0.3 kb human AFPpromoter,the recombinant adenovirus vector carrying EGFPgene can be specially expressed in AFP-producing HepG2cells.Therefore,this adenovirus system can be used as anovel,potent and specific tool for gene-targeting therapyfor the AFP positive primary hepatocellular carcinoma.     

Development and characterization of multidrug resistant human hepatocarcinoma cell line in nude mice

INTRODUCTION Tumor cell drug resistance represents a signif icant obstacle to successful chemotherapy. Cells which have acquired resistance to one anti-tumor drug usually show resistance to other anti-tumor drugs[1]. This cellular resistance is known as m…