基因工程腺病毒H101逆转A549/DDP细胞对顺铂耐药性的实验研究

背景及目的:耐药性产生是化疗失败的主要原因之一,克服耐药性的方法之一是使用逆转剂。目前尚无一种理想的、可应用于临床的顺铂(DDP)耐药逆转剂。本研究探讨基因工程腺病毒H101对DDP耐药性的逆转作用及其机制。方法:体外利用人肺腺癌细胞株A549的DDP耐药模型A549/DDP,采用MTT法检测H101对A549/DDP细胞耐药性的逆转作用。用流式细胞仪(FCM)测定细胞多药耐药蛋白1(multidrugresistantprotein1,MRP1)、谷胱甘肽鄄S鄄转移酶(GST)及TOPO鄄Ⅱ蛋白表达量,荧光鄄考马斯亮蓝法检测细胞内GSH含量,原子吸收法测定细胞内铂浓度。结果:A549/DDP细胞对DDP的耐药指数为14.3。加入H101后,DDP对A549/DDP的半数抑制浓度(IC50)由352.4μmol/L降至61.6μmol/L,逆转倍数为5.7倍。FCM检测结果显示,A549/DDP细胞的GST和TOPO鄄Ⅱ蛋白水平均较A549细胞高,而两种细胞内均未检测到MRP1的表达,经H101处理后的A549/DDP细胞胞内GST蛋白和TOPO鄄Ⅱ蛋白水平均明显下降。A549/DDP胞内GSH含量比A549高2倍多;H101感染A549/DDP细胞后,胞内的GSH含量下降,随着H101剂量的增加,胞内GSH含量逐渐下降,达A549细胞内GSH水平。原子吸收法测定细胞内铂含量的结果显示,A549细胞内铂含量是A549/DDP细胞内铂含量的3倍,加入H101后,A549细胞内铂的含量无明显变化,但A549/DDP细胞内铂的含量明显增加。结论:H101能逆转A549/DDP对DDP的耐药性,H101逆转DDP耐药性的机制可能是减少A549/DDP细胞内GSH和TOPOⅡ蛋白的水平,增加了A549/DDP细胞内铂的蓄积。     

氯丙嗪对耐药细胞系K562/AO2多药耐药逆转作用的研究

目的研究氯丙嗪对耐药细胞系K562/AO2多药耐药逆转作用.方法应用免疫组化观察K562/AO2细胞系的耐药蛋白表达情况,用MTT法测定不同浓度的氯丙嗪对K562/AO2细胞系耐药逆转作用,用流式细胞术测定不同浓度的氯丙嗪与K562/AO2细胞作用后细胞内罗丹明的蓄积情况,用半定量RT-PCR法测定氯丙嗪对K562/AO2细胞多药耐药基因(mdr-1)mRNA表达的影响.结果K562/AO2细胞不但P-gp表达阳性,而且肺耐药相关蛋白(lung resistanceelatedprotein,LRP)表达也阳性;氯丙嗪能增强多柔比星对K562/AO2细胞的杀伤作用(单用ADM组、氯丙嗪0.75 μg/mL+ADM组、氯丙嗪1.5μg/m L+ADM组和氯丙嗪3μg/mL+ADM组对K562/AO2的抑制率分别为5.2%、25.9%、39.1%和74.8%)增加K562/AO2细胞内罗丹明的蓄积(对照组、氯丙嗪0.75 μg/mL组、氯丙嗪1.5 μg/mL组和氯丙嗪3μg/mL组细胞内的荧光强度的均值分别为1.87、10.28、48.75和65.63)对K562/AO2细胞mdr-1 mRNA表达无明显影响(对照组mdr-1和β-actin的面积比为0.41,氯丙嗪组为0.42).结论氯丙嗪对K562/AO2细胞的耐药有较强的逆转作用,并呈剂量依赖关系.     

氯丙嗪对耐药细胞系K_(562)/AO_2多药耐药逆转作用的研究

目的 :研究氯丙嗪对耐药细胞系K562 /AO2 多药耐药逆转作用。方法 :应用免疫组化观察K562 /AO2 细胞系的耐药蛋白表达情况 ,用MTT法测定不同浓度的氯丙嗪对K562 /AO2 细胞系耐药逆转作用 ,用流式细胞术测定不同浓度的氯丙嗪与K562 /AO2 细胞作用后细胞内罗丹明的蓄积情况 ,用半定量RT PCR法测定氯丙嗪对K562 /AO2 细胞多药耐药基因 (mdr 1)mRNA表达的影响。结果 :K562 /AO2 细胞不但P gp表达阳性 ,而且肺耐药相关蛋白 (lungresistanceelatedprotein ,LRP)表达也阳性 ;氯丙嗪能增强多柔比星对K562 /AO2 细胞的杀伤作用 (单用ADM组、氯丙嗪 0 75 μg/mL ADM组、氯丙嗪 1 5μg/mL ADM组和氯丙嗪 3 μg/mL ADM组对K562 /AO2 的抑制率分别为 5 2 %、 2 5 9%、3 9 1%和 74 8% ) ;增加K562 /AO2 细胞内罗丹明的蓄积 (对照组、氯丙嗪 0 75 μg/mL组、氯丙嗪1 5 μg/mL组和氯丙嗪 3μg/mL组细胞内的荧光强度的均值分别为 1 87、 10 2 8、 48 75和65 63 ) ;对K562 /AO2 细胞mdr 1mRNA表达无明显影响 (对照组mdr 1和 β actin的面积比为0 41,氯丙嗪组为 0 42 )。结论 :氯丙嗪对K562 /AO2 细胞的耐药有较强的逆转作用 ,并呈剂量依赖关系     

青蒿琥酯对K562细胞凋亡诱导作用及其与亚砷酸的协同作用

目的研究青蒿琥酯体外诱导K562细胞凋亡的作用及其与亚砷酸的协同作用。方法采用MTT法、透射电镜技术、流式细胞术检测青蒿琥酯或(和)亚砷酸作用后K562细胞的凋亡发生情况。结果青蒿琥酯抑制K562细胞的增殖,IC50值为12.41μg/mL,其有时间、剂量-效应关系;12.50～50.00μg/mL的青蒿琥酯可诱导K562细胞凋亡,并具有一定的时间剂量-效应关系;12.50μg/mL青蒿琥酯与1.00μmol/L亚砷酸联合作用于K562细胞48h后,凋亡率为21.07%,与阴性对照(1.87%)、单独应用青蒿琥酯(7.45%)、亚砷酸(2.57%)相比,差异有统计学意义,χ2依次为1128.39、335.47和1058.40,P值均为0.000。结论青蒿琥酯对K562细胞具有凋亡诱导作用,并且与亚砷酸具有协同作用。     

青蒿琥酯对K562细胞凋亡诱导作用及其与亚砷酸的协同作用

目的：研究青蒿琥酯体外诱导K562细胞凋亡的作用及其与亚砷酸的协同作用.方法： 采用MTT法、透射电镜技术、流式细胞术检测青蒿琥酯或（和）亚砷酸作用后K562细胞的凋亡发生情况.结果：青蒿琥酯抑制K562细胞的增殖,IC50值为12.41 μg/mL,其有时间、剂量-效应关系;12.50～50.00 μg/mL的青蒿琥酯可诱导K562细胞凋亡,并具有一定的时间剂量-效应关系;12.50μg/mL青蒿琥酯与1.00 μmol/L亚砷酸联合作用于K562细胞48 h后,凋亡率为21.07%,与阴性对照（1.87%）、单独应用青蒿琥酯（7.45%）、亚砷酸（2.57%）相比,差异有统计学意义,χ^2次为1 128.39、335.47和1 058.40,P值均为0.000.结论： 青蒿琥酯对K562细胞具有凋亡诱导作用,并且与亚砷酸具有协同作用.     

榄香烯联合热疗对Raji细胞增殖的影响及其机制探讨

目的:观察榄香烯(elemene,ELE)联合热疗(hyperthermia,HTM)对人Burkitt’s淋巴瘤Raji细胞增殖及DNA拓扑异构酶Ⅰ和Ⅱ(TOPOⅠ,TOPOⅡ)表达的影响。方法:采用噻唑蓝还原法(MTT)观察ELE联合HTM对Raji细胞增殖的影响;流式细胞术(FCM)检测细胞周期;RT-PCR法检测细胞TOPOⅠ和TOPOⅡmRNA表达;Western Blot法检测细胞TOPOⅠ和TOPOⅡ蛋白表达。结果:与单纯HTM和单纯ELE比较,ELE联合HTM对Raji细胞增殖的抑制作用增强(P<0.05),呈时间和剂量依赖性,而ELE联合HTM作用Raji细胞24h、48h和72h后,IC50值(93μg/ml、68μg/ml和41μg/ml)小于单纯ELE IC50值(116μg/ml、84μg/ml和60μg/ml);ELE联合HTM阻滞Raji细胞于S期[(35.40±1.27)%、(42.38±2.50)%VS(48.88±1.93)%,P<0.05],并下调TOPOⅠ和TOPOⅡmRNA及蛋白的表达。结论:ELE联合HTM可增强对Raji细胞增殖的抑制作用,下调TOPOⅠ、TOPOⅡ表达可能是其机制之一。     

TNFα诱导K562/VCR和K562细胞凋亡及逆转其耐药作用的实验研究

目的探讨肿瘤坏死因子α(TNFα)体外诱导K562/VCR及K562细胞凋亡,及其逆转K562/VCR细胞多药耐药(MDR)的作用机制.方法以光镜、电镜、流式细胞仪观察细胞凋亡;流式细胞仪检测P-gp和bcl-2表达.MTT检测药物敏感性.结果 (1)TNFα浓度>100 U/ml,作用时间>48小时,2株细胞均可见典型凋亡现象,以K562/VCR细胞明显.(2)以TNFα 1 000 U/ml处理后,K562/VCR和K562细胞凋亡率分别为29.4%和10.7%.(3)K562/VCR经TNFα 1 000 U/ml处理72小时P-gp表达率从93.6%降至82.4%,bcl-2表达率从32.9%降至7.0%.(4)K562/VCR和K562细胞分别经TNFα 100 U/ml和1 000 U/ml处理后,VCR、Ara-C和VP-16的药物敏感性增加(P<0.05).结论 (1)TNFα可诱导K562/VCR和K562细胞凋亡,以前者更加敏感,且存在时间和剂量依赖性.(2)高浓度TNFα可下调bcl-2表达,但不显著改变P-gp表达.(3)TNFα能增加K562/VCR和K562细胞对VCR、Ara-C和VP-16的药物敏感性,以K562/VCR细胞更明显.(4)TNFα逆转K562/VCR多药耐药是通过诱导细胞凋亡,降低bcl-2表达,而非下调P-gp表达途径实现.     

抗VEGF抗体诱导K562细胞凋亡及其机制的研究

目的 观察抗VEGF抗体对K562细胞凋亡的影响,探讨VEGF抑制白血病细胞凋亡的机理.方法 采用半定量逆转录聚合酶链反应（RT-PCR）检测抗VEGF单抗对拓扑异构酶Ⅱ（TOPOⅡ）表达的影响;采用低浓度溴乙啶荧光测定法检测细胞TOPOⅡ的活性;应用琼脂糖凝胶电泳检测K562细胞凋亡的情况.结果 抗VEGF抗体能抑制K562细胞TOPOⅡ的表达,降低TOPOⅡ的活性,促进DNA解旋、断裂;抗VEGF单抗作用于K562细胞后,电泳结果显示有凋亡细胞特有的“梯状”条带.结论 抗VEGF单抗能引起白血病细胞凋亡,其原因可能是抗VEGF单抗抑制了白血病细胞TOPOⅡ基因的表达.     

氯丙嗪对耐药细胞系K562／AO2多药耐药逆转作用的研究

目的：研究氯丙嗪对耐药细胞系K562/AO2多药耐药逆转作用。方法：应用免疫组化观察K562／AO2细胞系的耐药蛋白表达情况，用MTT法测定不同浓度的氯丙嗪对K562/AO2细胞系耐药逆转作用，用流式细胞术测定不同浓度的氯丙嗪与K562／AO2细胞作用后细胞内罗丹明的蓄积情况，用半定量RT—PCR法测定氯丙嗪对K562／AO2细胞多药耐药基因(mdr-1)mRNA表达的影响。结果：K562／AO2细胞不但P-gP表达阳性，而且肺耐药相关蛋白(lung resistanceelated protein．LRP)表达也阳性；氯丙嗪能增强多柔比星对K562／AO2细胞的杀伤作用(单用ADM组、氯丙嗪0．75μg／mL+ADM组、氯丙嗪1．5μg／mL+ADM组和氯丙嗪3μg／mL+ADM组对K562／AO2的抑制率分别为5．2％、25．9％、39．1％和74．8％)；增加K562／AO2细胞内罗丹明的蓄积(对照组、氯丙嗪0．75μg／mL组、氯丙嗪1．5μg/mL组和氯丙嗪3μg／mL组细胞内的荧光强度的均值分别为1．87、10．28、48．75和65．63)；对K562／AO2细胞mdr-1 mRNA表达无明显影响(对照组mdr-1和β-actin的面积比为0．41，氯丙嗪组为0．42)。结论：氯丙嗪对K562／AO2细胞的耐药有较强的逆转作用，并呈剂量依赖关系。     

特异性环氧合酶抑制剂和抗癌药联用对胃癌细胞增殖的影响

目的观察特异性环氧合酶抑制剂(SCI)罗非昔布和塞来昔布与抗癌药联用对胃癌细胞增殖的影响。方法0.1μmol/L罗非昔布、50μmol/L塞来昔布与不同浓度5-氟尿嘧啶(5-Fu)、顺铂(DDP)、鬼臼乙叉甙(VP-16)单用、联用48 h。四甲基偶氮唑盐(MTT)法检测各组抑制率,中效原理和金正均法评价SCI与常用抗癌药联用的效果。结果0.1μmol/L罗非昔布和50μmol/L塞来昔布单用对胃癌细胞增殖抑制率分别为42.63%±1.26%和50.67%±2.35%。1、10、100μg/ml抗癌药单用对胃癌细胞增殖抑制率,5-Fu分别为39.75%±3.14%、49.96%±2.08%和87.93%±3.66%;DDP分别为48.28%±2.08%、59.46%±1.69%和88.23%±4.81%;VP-16分别为29.23%±3.27%、49.34%±3.75%和79.24%±2.44%。罗非昔布和塞来昔布与不同浓度抗癌药联用抑制率均高于单用,具有协同作用。结论罗非昔布和塞来昔布与抗癌药联用后起协同作用,SCI可作为抗癌药的化疗增敏剂。     

Altered stability of etoposide-induced topoisomerase II-DNA complexes in resistant human leukaemia K562 cells.

K562 leukaemia cells were selected for resistance using 0.5 microM etoposide (VP-16). Cloned K/VP.5 cells were 30-fold resistant to growth inhibition by VP-16 and 5- to 13-fold resistant to m-AMSA, adriamycin and mitoxantrone. K/VP.5 cells did not overexpress P-glycoprotein; VP-16 accumulation was similar to that in K562 cells. VP-16-induced DNA damage was reduced in cells and nuclei from K/VP.5 cells compared with K562 cells. Topoisomerase II protein was reduced 3- to 7-fold and topoisomerase II alpha and topoisomerase II beta mRNAs were each reduced 3-fold in resistant cells. After drug removal, VP-16-induced DNA damage disappeared 1.7 times more rapidly and VP-16-induced DNA-topoisomerase II adducts dissociated 1.5 times more rapidly in K/VP.5 cells than in K562 cells. ATP (1 mM) was more effective in enhancing VP-16-induced DNA damage in nuclei isolated from sensitive cells than in nuclei from resistant cells. In addition, ATP (0.3-5 mM) stimulated VP-16-induced DNA-topoisomerase II adducts to a greater extent in K562 nuclei than in K/VP.5 nuclei. Taken together, these results indicate that resistance to VP-16 in a K562 subline is associated with a quantitative reduction in topoisomerase II protein and, in addition, a distinct qualitative alteration in topoisomerase II affecting the stability of drug-induced DNA-topoisomerase II complexes.     

Non-ionic detergent Tween 80 modulates VP-16 resistance in classical multidrug resistant K562 cells via enhancement of VP-16 influx

The non-ionic detergent Tween 80, which is used as a solvent for lipophilic drugs such as VP-16 and Taxotere, was found to reverse VP-16 resistance of the P-glycoprotein-associated multidrug resistance phenotype via increasing VP-16 influx. In adriamycin-resistant human chronic myelogenous leukemia K562 cells (K562/ADM), which overexpress mdr1 mRNA, the accumulation of VP-16 was only about 10% that in wild-type K562 cells. Tween 80 enhanced VP-16 accumulation in K562/ADM cells but did not influence VP-16 accumulation in parental K562 cells. VP-16 efflux was rapid and similar in both sensitive and resistant cell lines and was not blocked by Tween 80 or verapamil. Under glucose-free conditions, VP-16 accumulation in K562/ADM cells was only half of that in K562 cells. Tween 80 increased VP-16 accumulation in K562/ADM cells in glucose-free medium. In growth inhibition assay, Tween 80 reversed K562/ADM sensitivity to VP-16 without cell damage. Taken together, Tween 80 reverses VP-16 sensitivity in multidrug-resistant K562 cells by increasing influx, which is considered to be the primary mechanism of VP-16 resistance in K562/ADM cells.     

整合素α5β1在IFNα-2b抑制白血病细胞系K562细胞增殖中的作用

背景与目的:慢性粒细胞白血病ph 细胞大量增殖与整合素β1介导的增殖抑制功能存在障碍密切相关。本研究通过观察整合素α5β1在干扰素(IFNα-2b)抑制慢性粒细胞白血病细胞K562增殖中的作用,探讨整合素β1在CML发病机制中的作用。方法:流式细胞仪检测K562细胞表面整合素α5β1的表达并检测纤维粘连蛋白(FN)与K562细胞的结合以及整合素α5β1单抗阻断两者结合的程度;MTT法测定整合素α5β1对IFNα-2b抑制K562细胞增殖的影响;RT-PCR法检测IFNα-2b作用后K562细胞中粘着斑激酶(FAK)表达量的改变。结果:整合素α5和β1在K562细胞表面高表达,分别为(97.59±1.04)%、(99.24±0.52)%,而健康人骨髓单核细胞为(64.05±2.38)%、(72.40±3.56)%;IFNα-2b不能改变其表达量,但可增强K562细胞整合素与FN的结合能力;K562细胞与FN的结合可被整合素α5和β1单抗阻断。与未处理组相比,IFNα-2b处理组的K562细胞发生增殖抑制(P<0.05),细胞内FAK基因表达水平增加2.21倍(P<0.05)。整合素α5和β1单抗可增强IFNα-2b引起的增殖抑制作用,并阻断IFNα-2b引起的FAK基因表达水平的增加。结论:IFNα-2b通过恢复整合素α5β1功能,增强FN与K562细胞表面整合素α5β1结合的能力而抑制K562细胞增殖并提高细胞内FAK表达量。     

Moxifloxacin enhances antiproliferative and apoptotic effects of etoposide but inhibits its proinflammatory effects in THP-1 and Jurkat cells

Etoposide (VP-16) is a topoisomerase II (topo II) inhibitor chemotherapeutic agent. Studies indicate that VP-16 enhances proinflammatory cytokines secretion from tumour cells, including IL-8, a chemokine associated with proangiogenic effects. Fluoroquinolones inhibit topo II activity in eukaryotic cells by a mechanism different from that of VP-16. The fluoroquinolone moxifloxacin (MXF) has pronounced anti-inflammatory effects in vitro and in vivo. We studied the effects of MXF and VP-16 on purified human topo II activity and further analysed their combined activity on proliferation, apoptosis and caspase-3 activity in THP-1 and Jurkat cells. Moxifloxacin alone slightly inhibited the activity of human topo II; however, in combination with VP-16 it led to a 73% reduction in enzyme activity. VP-16 inhibited cell proliferation in a time and dose-dependent manner. The addition of moxifloxacin for 72 h to low-dose VP-16 doubled its cytotoxic effect in THP-1 and Jurkat cells (1.8- and 2.6-fold decrease in cell proliferation, respectively) (P<0.004). Moxifloxacin given alone did not induce apoptosis but enhanced VP-16-induced apoptosis in THP-1 and Jurkat cells (1.8- and two-fold increase in annexin V positive cells and caspase-3 activity, respectively) (P<0.04). VP-16 induced the release of IL-8 in a time and dose-dependent manner from THP-1 cells. Moxifloxacin completely blocked the enhanced release of IL-8 induced by 0.5 and 1 microg ml(-1) VP-16, and decreased IL-8 release from cells incubated for 72 h with 3 microg ml(-1) VP-16 (P<0.001). VP-16 enhanced the release of IL-1beta and TNF-alpha from THP-1 cells, whereas the addition of MXF prevented the enhanced cytokine secretion (P<0.001). We conclude that MXF significantly enhances VP-16 cytotoxicity in tumour-derived cells while preventing VP-16-induced proinflammatory cytokine release. This unique combination may have clinical benefits and cytotoxic drug 'sparing effect' and should be further studied in vivo.     

中药提取物逆转K562/ADM细胞的耐药作用及其分子机制的探讨

目的 观察两种中药提取物黄芩苷、京尼平苷对多药耐药(MDR)K562/ADM细胞的耐药逆转作用,探讨其分子机制.方法 建立阿霉素(ADM)诱导K562/ADM细胞耐药模型,分别将不同浓度黄芩苷、京尼平苷作用于K562/ADM细胞,用四甲基偶氮唑盐(MTT)法检测其对化疗药物的敏感性,用逆转录聚合酶链反应(RT-PCR)检测多药耐药基因-1(mdr-1)、拓扑异构酶Ⅱ(TopoⅡ)基因在mRNA水平的表达变化.结果 两种中药提取物黄芩苷、京尼平苷,可增加K562/ADM细胞对ADM的敏感性,K562/ADM细胞增殖受到明显抑制,耐药逆转倍数分别为1.95倍及1.46倍;RT-PCR检测mdr-1基因表达减弱,Topo Ⅱ基因表达增强(P<0.01).结论 黄芩苷、京尼平苷可通过降低K562/ADM细胞mdr-1基因表达和提高TopoⅡ的表达来逆转白血病细胞MDR.     

粉防己碱对人口腔上皮癌多药耐药KB-MRP1细胞株多药耐药性的逆转作用

背景与目的:粉防己碱(tetrandrine,Tet)是从中草药粉防已的根块中提取的双苄基异喹啉生物碱,具有逆转P-糖蛋白(P-glycoprotein,P-gp)介导的肿瘤多药耐药(multidrug resistance,MDR)作用.本研究探讨粉防己碱对人口腔上皮癌多药耐药细胞株KB-MRP1耐药的逆转作用及其可能的机制.方法:采用MTT法检测不同浓度粉防己碱对KB-3-1细胞和KB-MRP1细胞的增殖抑制效应;MTT法检测顺铂(cisplatin,DDP)、长春新碱(vincristine,VCR)、阿霉素(adriamycin,ADM)、依托泊苷(etoposide,VP-16)对KB-3-1、KB-MRP1细胞增殖的抑制作用及加用粉防己碱时的变化;采用流式细胞仪检测细胞内ADM蓄积程度以及细胞凋亡.结果:1.5μg/ml及更低浓度的粉防己碱对KB-3-1和KB-MRP1细胞无明显细胞毒性作用.KB-MRP1对VCR、ADM、VP-16和DDP的耐药倍数分别为21.23、38.39、12.47和1.31.加入1 μg/ml粉防己碱后,KB-MRP1对VCR、ADM、VP-16的耐药逆转倍数分别为4.96、5.85和4.27倍.加入1.5 μg/ml粉防己碱后,KB-MRP1对上述化疗药物的敏感程度提高更明显.1.5 μg/ml浓度的粉防己碱可明显提高ADM在KB-MRP1细胞内的蓄积,增强VCR诱导的KB-MRP1细胞凋亡.结论:粉防己碱可以逆转KB-MRP1细胞的多药耐药,逆转效果与药物浓度有关,逆转机制可能与增加细胞内化疗药物蓄积和增强化疗药物诱导的细胞凋亡有关.     

RNAi对白血病细胞mdr-1基因和多药耐药表型的影响

目的:探讨RNA干扰技术(RNAi)对慢性粒细胞白血病急变细胞系K562/AO2细胞mdr1基因的抑制和耐药表型的逆转作用。方法:选择合成封闭mdr-1基因的小干扰序列(si-MDR1),以1个碱基突变的si-MDR1-mut为对照序列,在脂质体介导下转染至K562/AO2细胞系。RT-PCR和Western blot检测mdr1 mRNA及P-gp蛋白水平,流式细胞术分析细胞内柔红霉素(daunorubicin,DNR)积累量,并以四甲基唑蓝快速比色法(MTT)反映K562/AO2对阿霉素、长春新碱、足叶乙甙药物敏感性的变化。结果:实验证实该序列能高效封闭K562/AO2细胞内mdr-1基因表达,增加细胞内化疗药物DNR积累量,增强K562/AO2细胞对阿霉素、长春新碱、足叶乙甙的敏感性。结论:RNAi可以通过抑制mdr1基因表达,逆转K562/AO2细胞耐药表型。     

Indomethacin induces apoptosis and inhibits proliferation in chronic myeloid leukemia cells

A nonsteroidal anti-inflammatory drug (NSAID)--indomethacin (IN), was found to induce apoptosis and inhibit proliferation of K562 cells and primary culture bone marrow cells from six chronic myelogenous leukemia (CML) patients. IN induced cells apoptosis and inhibited cells proliferation in a dose-and time-dependent manner, the optimum IN concentration and incubation time for eliciting these effects were 400 micromol/l and 72 h, respectively. A synergic effect on Vp-16 (2.5 microg/ml) induced apoptosis was observed when combined with 100 micromol/l IN in K562 cells. RT-PCR results showed that IN down-regulated Bcl-2 mRNA expression, and did not change Bax mRNA expression; Western blot results confirmed that IN inhibited Bcl-2 protein expression, no influence was found on the translative level of bax protein. Our study indicate that IN induce apoptosis of CML cells by down-regulating Bcl-2 expression partially, and there is a potential significance in the treatment of CML.     

Reversal of drug resistance using hammerhead ribozymes against multidrug resistance-associated protein and multidrug resistance 1 gene

We examined the effects of suppressing multidrug resistance-associated protein (MRP) and multidrug resistance 1 (MDR1) gene expression in HCT-8DDP human colon cancer cell lines, which showed both cisplatin and multidrug resistance. Hammerhead ribozymes, designed to cleave MRP mRNA (anti-MRP Rz) and MDR1 mRNA (anti-MDR1 Rz), were transfected into the HCT-8DDP cells. Drug sensitivity was estimated by MTT assay in vitro. The HCT-8DDP/anti-MRP Rz cells were more sensitive to doxorubicin (DOX) and etoposide (VP-16) by 2.5- and 4.1-fold, respectively, compared with HCT-8DDP cells. The HCT-8DDP/anti-MDR Rz cells were more sensitive to DOX and VP-16 by 2.3- and 3.8-fold, respectively. The anti-MRP Rz and anti-MDR1 Rz significantly down-regulated resistance to DOX and VP-16, while anti-MRP Rz and anti-MDR1 Rz did not affect resistance to cisplatin, methotrexate and 5-fluorouracil. The hammerhead ribozyme-mediated specific suppression of MRP or MDR1 was sufficient to reverse multidrug resistance in the human colon cancer cell line.