Reversal of HCC Drug Resistance by Using Hammerhead Ribozymes against Multidrug Resistance 1 Gene

To reverse multidrug resistance（MDR） of HepG2 by anti-MDR1 hammerhead ribozyme, an anti-MDR1 hammerhead ribozyme was developed and delivered to P-gp-overproducing human hepatocarcinoma cell line HepG2 by a retroviral vector containing RNA polymerase Ⅲ promoter. The expression of mdrl/Pgp and Rz was detected in HepG2, HepG2 muhidrug-resistant cell line and HepG2 Rz-transfected cells by semi-quantitative RT-PCR and Western blot methods. Moreover, MTT assay was employed to detect the sensitivity of these ribozyme-transfected cells, and Rhodamine123 （Rh123） was used to test the function of Pgp. The Rz- transfected HepG2 cells became doxorubicin-sensitive, which was concomitant with the decreased MDR1 expression. The study showed that the retrovirus vector encoding the anti-MDR1 ribozyme may be applicable to the treatment of MDR cells.     

携反义mrp和mdr1双耐药基因的重组腺相关病毒载体的构建与鉴定

目的构建携带反义多药耐药相关蛋白基因(m rp)和反义多药耐药基因(m dr1)双耐药基因的重组腺相关病毒载体,以用于逆转肝细胞癌(HCC)多药耐药(M DR)的研究。方法将m rp基因cDNA 5′端500 bp的基因片段与m dr1基因cDNA 5′端600 bp的基因片段,用基因片段重叠法连接成为新的基因片段(m rp m dr1),并反向克隆到重组腺相关病毒载体系统(AAV H e lper-F ree System)表达质粒pAAV-IRES-hrGFP的多克隆位点,构建出重组表达质粒pAAV-IRES-hrGFP-(m rp m dr1)AS;再将pAAV-IRES-hrGFP-(m rp m dr1)AS与AAV H e lper-F ree System中的控制质粒pAAV-RC和辅助质粒pH e lper用脂质体转染法共转染293细胞,生成新型重组腺相关病毒载体rAAV 2-(m rp m dr1)AS。结果成功构建并包装出新型重组腺相关病毒载体rAAV 2-(m rp m dr1)AS,病毒滴度达2.5×108efu/m l。结论构建的rAAV 2-(m rp m dr1)AS可望能将反义m rp和m dr1基因片段导入HCC耐药细胞株。     

靶向重组腺病毒载体逆转肝癌细胞多药耐药的实验研究

目的 探讨携带多药耐药基因1(multidrug resistance gene 1,mdr1)反义RNA重组腺病毒载体靶向逆转甲胎蛋白阳性(AFP+)的肝癌多药耐药细胞HepG2R的疗效及作用机制.方法 将携带AFP启动子和EGFP基因的重组腺病毒载体Adeno-EGFP转染人正常肝细胞LO2(AFP-)、人宫颈癌细胞HeLa(AFP-)及HepG2(AFP+)细胞,检测EGFP基因在各细胞的转录水平,证实重组腺病毒载体的靶向性;将携带AFP启动子和mdr1基因反义核苷酸片段的重组腺病毒载体Adeno-asmdr转染HepG2R细胞和HepG2R裸鼠皮下移植瘤模型,检测Adeno-asmdr在体外和体内逆转HepG2R的活性.结果 EGFP基因在AFP阳性的HepG2细胞可得到显著的转录,而在LO2细胞和HeLa细胞,其转录和表达量极少,显示了该载体的良好转录活性以及靶向特异性;Adeno-asmdr转染HepG2R细胞后,mdr1转录水平下降;Rhodamine 123在细胞内聚集量有所下降;在裸鼠皮下移植瘤实验中,经Adeno-asmdr+ADM处理组,移植瘤体积无增大,TUNEL法检测移植瘤内凋亡细胞增加,而经PBS和ADM处理组移植瘤体积明显增大(P<0.05),ADM处理组移植瘤中出现少量的凋亡细胞,而PBS处理组移植瘤未见凋亡细胞.结论 实验构建的Adneo-asmdr重组腺病毒载体可在AFP阳性HepG2R细胞内特异靶向性表达目的 基因,有效降低mdr1基因产物P-gp170的表达,从而达到对HepG2R细胞MDR的逆转作用;结合化疗药物的作用,可以导致裸鼠皮下移植瘤细胞凋亡增加,阻止瘤体生长.     

逆转录病毒转染法建立耐药性大鼠CRBH-7919细胞系

目的:建立高效、稳定的大鼠CRBH-7919多药耐药细胞系.方法:利用逆转录病毒转染法将带有mdr1 cDNA全序列的逆转录病毒载体pHaMDR转入到大鼠CRBH-7919细胞中,MTT法检测细胞系在不同化疗药物作用下的存活率;免疫组化检测细胞的P-糖蛋白(P-GP)表达,RT-PCR检测细胞内mdr1 mRNA的表达量,PCR检测mdr1基因转移到细胞内的基因片段.结果:转基因的细胞系对阿霉素、丝裂霉素的耐药性分别提高 9和7.9倍,免疫组化见转基因细胞系P-GP表达增加,RT-PCR示细胞内mdr1 mRNA的表达量增加,PCR表明转基因细胞内扩增出mdr1片段.结论:利用逆转录病毒转染法成功建立了大鼠CRBH-7919多药耐药细胞系,该细胞系具有耐药强度高、耐药性稳定等特点.     

反义核酸对人肺腺癌细胞多药耐药逆转的实验研究

目的　探讨反义核酸对人肺腺癌细胞多药耐药的逆转效果。方法　以mdr1cDNA -9— 6为靶位点 ,合成反义核酸 (ATCCATCCCGACCTC)并用正义链作为对照 (GAGGTCGGGATGGAT) ,通过脂质体将其导入肺腺癌细胞A5 49/R ,分别采用逆转录聚合酶链反应、流式细胞仪、罗丹明试验及药敏试验观察两组细胞的mdr1mRNA、P糖蛋白 (Pgp)表达、罗丹明的聚集和对阿霉素的敏感性。结果　反义核酸处理的细胞mdr1mRNA下降 5 1 2 % ,正义组细胞和对照组细胞无明显变化、反义组细胞Pgp含量明显降低 ,细胞内罗丹明聚集 ,反义组 ,正义组和对照组的阿霉素IC50 分别为 0 0 0 9μg/ml、0 17μg/ml和 0 18μg/ml。 结论　反义核酸具有逆转人肺腺癌多药耐药的作用 ,其作用水平在mRNA或DNA水平 ,使Pgp的表达受到明显抑制 ,对阿霉素的敏感性明显提高。     

白血病细胞株HL60和HL60/DNR的多药耐药性

目的研究白血病细胞的多药耐药性（ＭＤＲ）。方法用ＲＴ－ＰＣＲ方法检测ＨＬ６０，ＨＬ６０／ＤＮＲＭＤＲ１的ｍＲＮＡ表达，用流式细胞仪分析单抗ＵＩＣ２标记的细胞株Ｐ糖蛋白（Ｐｇｐ）的表达，了解它们摄取和滞留荧光素Ｒ１２３的功能。结果ＨＬ６０／ＤＮＲ在ｍＲＮＡ水平高度表达ＭＤＲＩ，在蛋白质水平高度表达Ｐｇｐ，功能性试验中细胞内Ｒ１２３最终浓度ＨＬ６０为ＨＬ６０／ＤＮＲ的５０倍。结论ＨＬ６０／ＤＮＲ为典型的表达ＭＤＲ１的细胞株     

人MT1-MMP真核表达载体的构建及其在HepG2细胞中的表达及意义

目的：克隆人膜型基质金属蛋白酶1（MT1-MMP）基因,构建真核表达载体,并检测其在人肝癌细胞HepG2中的表达。方法：采用逆转录聚合酶链式反应（RT-PCR）从人正常肝组织中扩增MT1-MMP全长cDNA,将之与pMD18-T载体连接,测序后将该片段亚克隆至真核表达载体pcDNA3.1中。将构建好的pcDNA3.1/MT1-MMP真核表达载体经酶切鉴定后,采用脂质体法转染入HepG2细胞,经G418筛选,得到阳性克隆细胞株。应用RT-PCR检测转染前后该细胞株MT1-MMP mRNA表达水平。结果：①RT-PCR获得长度约为704 bp的目的片段,与预期片段相符;②将pcDNA3.1/MT1-MMP真核表达载体经EcoRⅠ和BamHⅠ双酶切鉴定,得到约5 400 bp和704 bp两个片段,测序结果证实所插入目的片段与GenBank中MT1-MMP cDNA序列匹配;③重组质粒转染株MT1-MMP mRNA表达水平（1.66±0.43）明显高于空质粒组（1.21±0.25）和对照组（1.19±0.18)(P<0.01）。结论：成功构建pcDNA3.1/MT1-MMP真核表达载体,并在人肝癌细胞株HepG2中稳定表达。     

Cytokine-induced killer cells showing multidrug resistance and remaining cytotoxic activity to tumor cells after transfected with mdr1 cDNA

Background Routine treatment of cancer such as surgery, radiation or chemotherapy is sometimes unable to erdiacate metastatic malignant cells. So we tried a new method and increased the adoptive immunotherapy of Cytokine-induced killer (CIK) cells in tumor patients and the multidrug resistance (mdrl) cDNA was transfected into CIK cells. Methods CIK cells were obtained from peripheral blood and induced by IFN-γ, anti-CD3 monoclonal antibody, IL-2 and IL-1. CIK cells were transfected with plasmid PHaMDR containing human mdrl cDNA by electroporation. RT-PCR was used to detect mdrl mRNA in transfected CIK cells. P-glycoprotein (P-gp) expressed on surface of CIK cells was assayed by FITC-conjugated anti-P-gp monoclonal antibody and flow cytometry. Multidrug resistance to doxorubicin and colchicine and cytotoxic activity to human breast cancer cell line MCF7 were performed using MTT method. Results mdrl mRNA was detected in transfected CIK cells. P-gp was expressed on the surface of the transfected CIK cells, and the P-gp positive cells reached 21%-37% of the total CIK cells after transfection. The IC50 to doxorubicin increased to 22.3-45.8 times, and that to colchicines to 6.7-11.35 times, as compared to those of untransfected CIK cells. However, the cytotoxic activity to MCF7 cell line remained unaltered. Conclusions CIK cells were successfully transfected with mdrl cDNA by using electroporation. The transfected CIK cells had the characteristics of multidrug resistance without change in their cytotoxic activity to tumor cells.     

Functional and histochemical analysis of MDR3 P-glycoprotein in a tetracycline-controlled gene expression system

Aim of the present study was to establish a cell system to study the physiological function of human MDR3 P-glycoprotein in cellular phosphatidylcholine (PC) secretion. MDR3 cDNA was expressed in HeLa cells using the tet-off system together with a luciferase reporter gene. MDR3 Pgp expression was turned on upon removal of doxycycline as shown by Western blot analysis. Immunohistochemistry using a specific anti human MDR3 Pgp antibody revealed a prominent staining of MDR3 Pgp covering the cytoplasm and the area of the plasma membrane. In presence of doxycycline MDR3 Pgp expression was turned off. For analysis of PC secretory activity, MDR3 Pgp expressing and non-expressing cells as well as control HeLa cells with low endogenous MDR3 were preincubated with [(3)H]choline for synthesis of cellular [(3)H]PC. Cells were then incubated for 2 h in media with 0-4 mM taurocholate (TC) and release of cellular [(3)H]PC was recorded. [(3)H]PC secretion was observed in presence of TC without impairing cell viability. There was a significant increase in [(3)H]PC excretion in MDR3 Pgp expressing cells compared to non-expressing controls (e.g. 4.5 fold at 4 mM TC), revealing a high efficiency of transport activity (turnover). From the data it is concluded that the MDR3 Pgp expressing cell system under control of a doxycycline responsive promotor is functionally active and provides a tool to further study MDR3 Pgp mediated transport.     

逆转录病毒转染法建立兔VX-2多药耐药株

目的：建立VX-2多药耐药(MDR)细胞(VX-2mdrI)。方法：利用逆转录病毒转染法将带有mdrI cDNA全序列的逆转录病毒载体pHaMDR1转入到兔VX-2细胞中，MTT法检测细胞在不同化疗药物作用下的存活率；免疫组化检测细胞的P-糖蛋白(P-gp)表达，RT-PCR检测细胞内mdrI mRNA的表达量．结果：转基因的细胞对吡柔比星、秋水仙素的耐药性分别提高10和25倍，免疫组化见转基因细胞中P-gp表达增加，RT-PCR示细胞内mdrI mRNA的表达量增加。结论：利用逆转录病毒转染法构建了兔VX-2 MDR细胞。     

The Roles of Four Multi-drug Resistance Proteins in Hepatocellular Carcinoma Multidrug Resistance

The roles of multi-drug resistance protein 1 (MDR1), multi-drug resistance related pro- tein 1 (MRP1), lung resistance protein (LRP) and breast cancer resistance protein (BCRP) in the multi-drug resistance (MDR) of hepatocellular carcinoma (HCC) were studied. By exposing HepG2 cell line to progressively increased concentrations of adriamycin (ADM), HepG2 multi-drug resistant subline (HepG2/ADM) was induced. The MDR index of HepG2/ADM was detected by using MTT. The expressions of the four MDR proteins in the three cell lines (L02, HepG2, HepG2/ADM) were investigated at mRNA and protein levels by real-time RT-PCR and Western blot respectively. Our re- sults showed that when the ADM concentration was under 100 μg/L, HepG2 could easily be induced to be drug-resistant. The IC50 of the HepG2/ADM to ADM was 282 times that of HepG2. The expres- sion of MDR1 and BCRP mRNA in HepG2/ADM cells were 400 and 9 times that of HepG2 cells re- spectively while there was no difference in the mRNA expressions of MRP1 and LRP. There was no difference between HepG2 and L02 cells in the mRNA expressions of the four genes. At the protein level, the expressions of MDR1, BCRP and LRP but MRP1 in HepG2/ADM were significantly higher than those of HepG2 and L02. Between HepG2 and L02, there was no difference in the ex- pressions of four genes at the protein level. HepG2/ADM is a good model for the study of MDR. The four genes are probably the normally expressed gene in liver. The expressions of MDR1 and BCRP could be up-regulated by anti-cancer agents in vitro. The MDR of HCC was mainly due to the up-regulation of MDR1 and BCRP but MRP1 and LRP. These findings suggest they may serve as targets for the reversal of MDR of HCC.     

KBv200细胞株耐药逆转前后HLA、B7抗原的表达

目的 探讨肿瘤多药抗性细胞的免疫逃避机制。方法 利用特异性切割mdr1的核酶为工具,以表达Mdr1的耐药细胞株KBv200为靶细胞,采用脂质体转染技术,将含核酶的质粒pHβApr-1neo/5mR3及空载体pHβApr-1neo导入KBv200及其亲本KB细胞内,运用Northern-blotting、免疫组化方法观察核酶对mdr1 mRNA及P-gp的影响,运用流式细胞仪技术检测各种不同细胞亚株HLA-Ⅰ、HLA-Ⅱ、B7-1、B7-2的表达。 结果 含核酶的质粒pHβApr-1neo/5mR3及空载体pHβApr-1neo可以在KB、KBv200细胞中稳定表达,核酶可以特异性地切割mdr1,导致KBv200/5mR3的mdr1 mRNA含量下降,P 糖蛋白（P-gp）表达减低,各种不同细胞亚株均表达较强的HLA-Ⅰ类抗原,而HLA-Ⅱ、B7-1、B7-2的表达较低。各亚株HLA-Ⅰ表达无明显差异,但HLA-Ⅱ、B7-1、B7-2的表达变化较大,KB的HLA-Ⅱ、B7-1、B7-2的表达较KBv200强,经化疗药物作用后KB的HLA-Ⅱ、B7-2进一步表达增强,核酶逆转后,KBv200/5mR3 HLA-Ⅱ、B7-1、B7-2的表达趋于接近KB水平。 结论 mdr1-核酶在细胞内具有一定的逆转肿瘤多药抗性的生物学效应;多药耐药细胞和敏感株细胞有着不同的免疫逃避特点,与敏感株相比,KBv200较易逃避机体的免疫反应。     

五味子乙素对转染多药耐药1基因的MCF-7细胞的多药耐药逆转作用

目的 探讨五味子乙素(SchB)对转染多药耐药1基因(MDR1)的人乳腺癌细胞MCF-7的多药耐药逆转作用及相关机制。方法 将人MDR1基因导入MCF-7细胞,形成耐药细胞株MCF-7／MDR1;用该细胞株为模型评价SchB的体外逆转多药耐药作用,用MTT法进行化疗药物单独或与SchB联合作用时对耐药细胞的IC50比较,计算逆转倍数。结果 转染细胞MCF-7／MDR表现为P糖蛋白高表达,对阿霉素、长春新碱、紫杉醇、高三尖杉酯的抗药性均增加;SchB(25μmol／L)显著减少阿霉素、长春新碱、紫杉醇和高三尖杉酯对MCF-7／MDR细胞的IC50,逆转倍数达6．03-23．94倍;SchB(25μmol／L)使MCF-7／MDR细胞对若丹明123的胞内积聚增加约5倍。效果与维拉帕米10μmol／L浓度时相当;但SchB(25μmol／L)不影响MCF-7／MDR细胞的P-糖蛋白表达。结论 SchB能有效逆转转染MDR1的MCF-7细胞的多药耐药,其机制可能是抑制了P-糖蛋白的药物外排生物学活性。     

Chemoprotection of transfer of multidrug resistance gene into human hematopoietic progenitor cell

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The role of c-myc in regulating mdr1 gene expression in tumor cell line KB

Ｔｈｅｃ ｍｙｃｐｒｏｔｏ ｏｎｃｏｇｅｎｅｐｌａｙｓａｒｏｌｅｉｎｍａｎｙｃｅｌｌｕｌａｒｐｒｏｃｅｓｓｅｓ ,ｓｕｃｈａｓｐｒｏｌｉｆｅｒａｔｉｏｎ ,ｄｉｆｆｅｒｅｎｔｉａｔｉｏｎａｎｄａｐｏｐｔｏｓｉｓ Ｉｔｉｓａｎｅａｒｌｙ ｒｅｓｐｏｎｓｅｇｅｎｅｎｅｃｅｓｓａｒｙｆｏｒｃｅｌｌ ｃｙｃｌｅｐｒｏｇｒｅｓｓｉｏｎ (Ｇ1 Ｓｔｒａｎｓｉｔｉｏｎ)ａｎｄａｃｔｉｖａｔｅｓｑｕｉｅｓｃｅｎｔｃｅｌｌｓｉｎｔｏｔｈｅｃｅｌｌｃｙｃｌｅ (Ｇ0 Ｇ1ｔｒａｎｓｉｔｉｏｎ) Ｄｏｗｎ ｒｅｇｕｌａｔｉｏｎｏｆｃ …     

Apaf-1通过wnt/β-catenin信号通路调控肝癌的机制研究

目的 研究Apaf-1基因在wnt/β-catenin信号通路中的作用及在肝癌细胞中的调控表达机制.方法 通过TOP-flash实验验证Apaf-1基因在wnt/β-catenin信号通路中调控作用机制;采用实时定量PCR方法检测各种肝癌细胞株(HepG2、H HCC、HB611)及正常肝细胞株(LO2)中Apaf-1基因的表达量;构建Apaf-1 RNA干扰质粒,转染到HepG2中并检测转染效率,检测相关基因及蛋白表达.结果 TOPflash实验发现Apaf-1可以抑制wnt/β-catenin信号通路,并且这种抑制作用具有剂量依赖效应;在肝癌细胞株中,Apaf-1表达量较正常肝细胞表达量降低,且在HepG2细胞株中表达量最低;在肝癌细胞株(HepG2)中RNA干扰Apaf-1基因,Apaf-1基因的的表达量显著降低,wnt信号通路下游基因及蛋白(β-catenin、Cyclin A、CDK2、wnt5a、STAT3、EGFR、APC)的表达量均显著性升高或降低,差异有统计学意义(P＜0.05).结论 Apaf-1基因通过wnt/β-catenin信号通路在肝癌细胞的生成过程中具有重要功能.     

端粒酶逆转录酶线粒体转位促进肝癌细胞干性及耐药的研究

目的 探讨人端粒酶逆转录酶(human telomerase reverse enzyme,hTERT)线粒体转位对肝癌细胞干性及耐药的影响.方法 采用大剂量顺铂(CDDP)冲击、间歇诱导的方法诱导肝癌细胞HepG2、Huh7耐药,构建耐药细胞株HepG2/CDDP、Huh7/CDDP,CCK-8检测细胞耐药能力;Western blot检测细胞线粒体hTERT表达情况;激光共聚焦显微镜观察细胞线粒体膜电位;流式细胞术检测耐药细胞干性相关蛋白CD133、EpCAM表达情况;克隆形成实验检测细胞克隆形成能力;Western blot检测耐药细胞干性相关因子OCT-4蛋白表达水平变化.结果 与亲本细胞HepG2[耐药指数(7.69±0.86)μg/mL及Huh7 (7.18±0.35) μg/mL]相比,耐药细胞株对CDDP耐药指数明显增加[HepG2 (41.16±0.42) μg/mL,Huh7 (33.48±0.33)μg/mL,P＜0.01],经顺铂(CDDP)诱导耐药细胞线粒体hTERT表达显著升高,线粒体膜电位增强,CD133+细胞比例[HepG2 (1.44±0.41),HepG2/CDDP (23.15±1.55),P＜0.01]及EpCAM+细胞比例[HepG2 (0.85 ±0.10),HepG2/CDDP (3.96 ±0.10),P＜0.01]增加,克隆形成能力增强,干性相关因子OCT4蛋白表达水平增加.结论 经顺铂诱导的肝癌耐药细胞线粒体hTERT转位显著增加,且具有明显的肿瘤干细胞特征.     

多元药物抗性基因(mdr-1)在白血病细胞中的表达

多元药物抗性基因(multidrug resistance gene,mdr-1)编码 P 170膜蛋白,可使细胞对多种结构不同的细胞毒药物产生抗性。本文以 mdr-1 cDNA为探针,做白细胞总 RNA 斑点杂交分析了5例髓性白血病人mdr-1的mRNA水平。说明mdr-1基因在此类患者的白细胞中的表达有明显差异,同一病人治疗前后也有改变。所建立的观查临床标本中基因表达水平的方法,具广泛的应用价值。     

Comparison of antileukemic immunity mediated by dendritic cells derived from multidrug resistant leukemia K562/A02 cells and sensitive K562 cells

Dendritic cells (DCs), as the most potent antigen presenting cells in vivo, are central to generating specific immune responses and can be used as important vectors in antitumour immunity. DCs loaded with tumour antigens can induce specific antitumour response in cytotoxic T lymphocytes (CTL) . P-glycoprotein ( P-gp), a product of mdrl gene, widely overexpressed in many multidrug resistant (MDR) tumour cells, is a main mechanism that makes tumour cells escape from death induced by chemotherapeutic agents.