RNA干扰抑制MDR1表达并逆转Bel7402/5-Fu肝癌细胞耐药性的研究

目的：研究小片段RNA干扰对肝癌耐药细胞系Bel7402／5-Fu中多药耐药基因（muhidrug resistance 1，MDR1）及其蛋白产物P-gP表达的抑制作用和逆转其耐药性的效果。方法：合成针对MDR1启动子区域的RNA干扰小片段，转染肝癌耐药细胞Bel7402／5-Fu。通过RT-PCR和Westem blot方法，在mRNA和蛋白水平评价RNA干扰对MDR1表达的影响。MTT法检测RNA干扰逆转Bel7402／5-Fu细胞耐药性的效果，按实验组和对照组细胞的半数抑制剂量（IC50）计算RNA干扰对细胞耐药倍数的改变和RNA干扰组细胞的耐药逆转倍数。以流式细胞仪比较各组细胞在相同浓度化疗药物作用时细胞的凋亡情况。结果：在耐药肝癌细胞Be17402／5-Fu中，RNA干扰明显抑制了MDR1 mRNA和蛋白产物P-gP的表达水平，其表达仅为对照组细胞的22．55％和25．49％（P〈0．01）。在相同浓度化疗药物的作用下，RNA干扰组Bel7402／5-Fu细胞凋亡比例显著高于对照组（P〈0．01），表明细胞耐药性显著下降，对5-Fu的耐药逆转倍数为14．88倍。结论：肝癌耐药细胞Bel7402／5-Fu中，RNA干扰对MDR1 mRNA及其蛋白产物P-gP的表达水平有显著抑制作用，具有良好的逆转耐药性的效果。     

多药耐药基因在肺癌患者外周血中的表达及意义

目的：探讨肺癌患者外周血中多药耐药基因（MDR1）的表达水平及其与临床病理因素、化疗的关系。方法：经病理证实为肺癌的患者40例（病理组），鳞状细胞癌13例，腺癌14例，小细胞未分化癌13例。应用荧光定量PCR（FQ-PCR）技术，动态监测化疗前后MDR1 mRNA的表达，并与30例健康者（对照组）的检测结果进行比较分析。结果：病理组化疗前MDR1mRNA的检出率明显高于健康对照组，差异具有统计学意义（P〈0．05）；各种类型的肺癌患者随着化疗次数的增多MDR1mRNA的表达增强；化疗前后肺鳞状细胞癌和肺腺癌MDR1mRNA的表达明显高于小细胞肺癌，差异具有统计学意义（P〈0．05）。结论：化疗可诱导各种病理类型肺癌MDR1mRNA表达增加；肺腺癌和肺鳞癌可能为原发性MDR，小细胞肺癌可能为获得性MDR；肺癌患者MDR1mRNA表达程度可作为指导化疗用药及预测预后的指标。     

MDR1 siRNA对结肠癌细胞多药耐药性的影响

[目的]探讨MDR1 siRNA对结肠癌细胞多药耐药性的影响。[方法]设计合成两种针对MDR1 mRNA的siRNA双链分子（#4123 MDR1 siRNA和#4029 MDR1 siRNA）,并转染入COLO 320DM和HT-29结肠癌细胞,观察其对结肠癌细胞MDR1 mRNA和P-gp表达的影响。并分别与5-FU、阿霉素和长春新碱等抗肿瘤药联用,观察结肠癌细胞活力的变化。用阿霉素处理后,观察转染MDR1 siRNA结肠癌细胞的细胞内阿霉素累积浓度的变化。RT-PCR检测细胞MDR1 mRNA的表达,免疫印迹法检测细胞P-gp的表达,MTT法检测细胞活力,流式细胞术检测细胞内阿霉素累积浓度。[结果]#4123 MDR1 siRNA和#4029 MDR1 siRNA均可抑制COLO 320DM结肠癌细胞MDR1 mRNA和P-gp的表达,其最低有效浓度分别为5nmol/L和25nmol/L。同时MDR1 mRNA和P-gp表达的抑制伴随着抗肿瘤药（5-FU、阿霉素和长春新碱）对COLO 320DM结肠癌细胞毒性的增强和细胞内阿霉素累积浓度的增加。而在对照HT-29结肠癌细胞却观察不到此效应。[结论]MDR1 siRNAs能特异逆转结肠癌细胞的多药耐药性,为MDR1/P-gp依赖的多药耐药性结肠癌的治疗提供了一条新的途径。     

MDR1 siRNA对结肠癌细胞多药耐药性的影响

 [目的]探讨MDR1 siRNA对结肠癌细胞多药耐药性的影响。[方法]设计合成两种针对MDR1 mRNA的siRNA双链分子（#4123 MDR1 siRNA和#4029 MDR1 siRNA）,并转染入COLO 320DM和HT-29结肠癌细胞,观察其对结肠癌细胞MDR1 mRNA和P-gp表达的影响。并分别与5-FU、阿霉素和长春新碱等抗肿瘤药联用,观察结肠癌细胞活力的变化。用阿霉素处理后,观察转染MDR1 siRNA结肠癌细胞的细胞内阿霉素累积浓度的变化。RT-PCR检测细胞MDR1 mRNA的表达,免疫印迹法检测细胞P-gp的表达,MTT法检测细胞活力,流式细胞术检测细胞内阿霉素累积浓度。[结果]#4123 MDR1 siRNA和#4029 MDR1 siRNA均可抑制COLO 320DM结肠癌细胞MDR1 mRNA和P-gp的表达,其最低有效浓度分别为5nmol/L和25nmol/L。同时MDR1 mRNA和P-gp表达的抑制伴随着抗肿瘤药（5-FU、阿霉素和长春新碱）对COLO 320DM结肠癌细胞毒性的增强和细胞内阿霉素累积浓度的增加。而在对照HT-29结肠癌细胞却观察不到此效应。[结论]MDR1 siRNAs能特异逆转结肠癌细胞的多药耐药性,为MDR1/P-gp依赖的多药耐药性结肠癌的治疗提供了一条新的途径。     

抑制P-糖蛋白表达逆转视网膜母细胞瘤多药耐药研究

目的:探讨应用RNA干扰(RNAi)技术逆转视网膜母细胞瘤多药耐药的可行性。方法:将设计合成的针对多药耐药基因MDR1的特异性小分子干扰RNA(siRNA),用脂质体转染具有MDR1基因高表达的视网膜母细胞瘤耐药细胞株SO-Rb50/VCR。用实时定量RT-PCR技术和Westernblot分别测定转染前后细胞MDR1mRNA及P-糖蛋白(P-gp)表达的变化;用CCK-8法和TUNEL法检测转染前细胞株(VCR组),转染后细胞(VCR+siRNA组)对不同浓度长春新碱、依托泊苷和卡铂药物敏感性。结果:VCR+siRNA组较VCR组比较,MDR1基因在mRNA水平和蛋白水平表达显著下降,差异具有统计学意义。随着长春新碱、依托泊苷浓度的升高VCR+siRNA组较VCR组比较,细胞存活率显著降低,差异具有统计学意义。不同浓度的卡铂作用于VCR组、CT组和VCR+siRNA组细胞存活率、细胞凋亡率各组见未见显著性差异。随着长春新碱、依托泊苷浓度的升高,VCR+siRNA组较VCR组比较,细胞凋亡率显著性升高,差异具有统计学意义。结论:在SO-Rb50/VCR细胞中,针对MDR1合成的siRNA能够有效地抑制MDR1mRNA和P-gp的表达,并能恢复肿瘤细胞对长春新碱和依托泊苷的敏感性。应用RNAi技术,能够逆转Pgp引起的视网膜母细胞瘤多药耐药性。     

小干扰RNA沉默MAT1基因治疗胰腺癌的实验研究

目的了解体外转录法合成的小干扰RNA（siRNA）沉默MAT1基因对胰腺癌的体内体外抗癌效应。方法用siPORT-脂质体（1ipid）中性阳离子脂质体转染由体外转录法合成、Cy3荧光标记的双链siRNA人胰腺癌BxPC3细胞,观察对胰腺癌细胞生长和细胞周期曲线的影响,检测MAT1基因被siRNA沉默后mRNA和蛋白质的表达水平。在裸鼠胰腺癌皮下移植瘤瘤体内直接注射siRNA观察抑瘤效应。结果合成的4条MAT1-siRNA序列中有一半可显著抑制BxPC3细胞的生长。体外转染MAT1-siRNA72h后,BxPC3细胞生长抑制率达34．9％（P〈0．01）;83．9％的BxPC3细胞滞留于G。／G,期,而空白对照组仅59．86％（P〈0．01）。体外转染MAT1-siRNA48h后MAT1-mRNA水平下调了80．12％,72h后MAT1蛋白质水平下调了50．12％,与各对照组相比差异均有统计学意义（均P〈0．01）。MAT1-siRNA注射组裸鼠移植瘤重量和体积均明显低于对照组（均P〈0．05）,抑瘤率达42．53％。结论siRNA介导的MAT1基因沉默在体外实验中显著抑制了胰腺癌细胞的生长,在体内实验中对裸鼠胰腺癌皮下移植瘤产生明显的抑瘤效应。     

人层粘连蛋白受体调节胃癌细胞多药耐药性的实验研究

目的：探讨相对分子质量为67000的人层粘连蛋白受体（LR）对胃癌细胞多药耐药性（MDR）的调节作用及其机制。方法：应用DNA重组技术构建LR前体蛋白（LRP）的反义RNA表达载体,并借助脂质体将其导入胃癌MDR细胞SGC7901／VCR中。用Western印迹法检测ＬＲ在胃癌细胞中的表达,ＭＴＴ法测定细胞对化疗药物的敏感性,流式细胞仪测定细胞周期以及阿霉素在细胞内的蓄积和潴留。结果：转染LRP反义RNA表达载体显著降低了LR在SGC7901／VCR细胞中的表达。转染细胞（SGC7901／VCR－anLRP)对长春新碱、阿霉素、5－氟尿嘧啶和顺铂的敏感性明显升高,细胞内蓄积和潴留的阿霉素也明显增多。细胞周期分析表明,SGC7901／VCR－anLRP细胞发生了G1期阻滞,并出现了自发性凋亡。结论：LR可能通过影响药物蓄积和细胞凋亡参与对胃癌细胞MDR的调节。     

腺病毒介导p53基因逆转乳腺癌耐药的实验研究

目的探讨腺病毒介导p53基因（Ad-p53）对人乳腺癌阿霉素（ADM）耐药细胞株MCF-7／ADM的耐药性及多药耐药基因1（MDR1）的影响。方法以Ad-p53转染MCF-7／ADM细胞株,流式细胞术检测p53蛋白变化;锥虫蓝活细胞拒染法观察细胞生长情况;MTT法观察MCF-7／ADM细胞对阿霉素耐药性的变化,实时荧光RT—PCR法检测MDR1 mRNA变化。结果流式细胞术观察到MCF-7／ADM细胞经MOI50的Ad-p53作用48h后,p53蛋白表达率由10．24％升高到36．20％;细胞抑制率为7．4％（P=0．003）;逆转MCF-7／ADM对ADM的耐药倍数11．6倍（P=0．001）;实时荧光RT-PCR检测结果显示MDR1 mRNA相对表达量由1．25±0．01下降至0．91±0．01（P=0．011）。结论腺病毒介导p53基因能抑制MCF-7／ADM细胞MDR1基因的表达,并能部分逆转MCF-7／ADM的耐药性,增加阿霉素化疗敏感性。     

蛋白激酶C活性、表达及亚细胞分布与KBV200细胞多药耐药相关性的研究

目的研究多药耐药肿瘤细胞PKC活性、PKC亚型的表达和亚细胞分布与KBV200细胞多药耐药的关系。方法MTT法检测敏感株KB和耐药株KBV200细胞的耐药性；印掺入法测定PKC的活性；Western blot法检测KBV200及其亲本KB细胞株PKC亚型的表达和亚细胞分布。结果长春新碱（VCK）和阿霉素（ADK）对KBV200细胞的IC50值分别高于KB细胞（P〈0．01）；耐药指数（RI）分别为65．03和19．8。KBV200细胞的膜组分、浆组分的PKC活性均较KB细胞高,KBV200细胞的总PKC活性是KB细胞的2．12倍。Western blot结果发现KBV200和KB细胞膜组分及浆组分均有PKCq的表达，且KBV200细胞的表达较KB明显增强。PMA可升高KBV200细胞的PKC总活性和膜组分PKC活性，降低浆组分PKC活性、表达（P〈0．01）；PMA可升高VCR、ADK对KBV200细胞的IC50值（P〈0．01）。SP可降低PKC活性；SP预孵育使PKCα膜组分和浆组分的表达均降低，可降低VCR、ADK对KBV200细胞的IC50值（P〈0．01）。结论KBV200细胞的PKC活性、表达、亚细胞分布与KB细胞有明显差别，这种差别可能与KBV200耐药性的变化密切相关，在PKC亚型中，PKCα的表达明显高于其他亚型，且高于亲本株，提示KBV200细胞中PKCα与多药耐药相关。     

祛风通络方对大鼠系膜细胞增殖及转化生长因子β1和白细胞介素6 mRNA表达的影响

目的：观察祛风通络方对脂多糖（lipopolysaccharide，LPS）诱导的大鼠肾小球系膜细胞（mesangial cell，MC）增殖及其分泌的转化生长因子β1（transforming growth factor—betal，TGF—β1）和白细胞介素6（interleukin-6，IL-6）mRNA表达的影响。方法：采用血清药理学方法，体外培养大鼠肾小球系膜细胞，分为正常对照组、模型组、蒙诺（福辛普利钠）组和祛风通络方组。并采用甲基噻唑基四唑（methyl thiazolyl tetrazolium，MTT）法检测大鼠MC增殖情况，逆转录聚合酶链反应法检测TGF—β1和IL-6mRNA的表达。结果：与正常对照组比较，模型组大鼠肾小球系膜细胞增殖升高（P〈0．05）；与模型组比较，祛风通络方组大鼠肾小球系膜细胞增殖受到抑制（P〈0．05），且祛风通络方作用优于蒙诺（P〈0．05）。模型组系膜细胞TGF-β1mRNA表达高于正常对照组（P〈0．01）；祛风通络方组和蒙诺组系膜细胞TGF—β1mRNA表达低于模型组（P〈0．01）；祛风通络方组与蒙诺组比较，TGF—β1mRNA的表达降低（P〈0．01）。LPS刺激后可提高大鼠系膜细胞内IL-6mRNA的表达，与正常对照组比较，模型组IL-6mRNA表达上升，差异有统计学意义（P〈0．01）；祛风通络方组、蒙诺组与模型组比较，IL-6mRNA表达下降（P〈0．01）；祛风通络方降低IL-6mRNA表达的作用亦优于阳性对照药蒙诺（P〈0．01）。结论：祛风通络方对大鼠MC增殖及其TGF—β1和IL-6mRNA表达均有明显的抑制作用。     

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

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TRAIL抑制胃癌多药耐药基因MDR1/P-gp的表达

目的观察肿瘤坏死因子相关凋亡诱导配体(TRAIL)对胃癌耐药细胞株SGC-7901/VCR多药耐药基因MDR1及其编码P-gp蛋白表达的影响,探讨以TRAIL为靶点逆转胃癌多药耐药的机制。方法 SGC-7901/VCR细胞株经不同浓度的TRAIL处理48 h后,RT-PCR检测各组胃癌细胞株中多药耐药MDR1 mRNA的表达情况,同时用ELISA法检测各组胃癌细胞株中P-gp表达的含量。结果不同浓度TRAIL(50、100、200、400μg/L)作用于细胞后,胃癌耐药细胞株SGC-7901/VCR的MDR1/P-gp表达受不同程度抑制,与对照组相比差异均具有统计学意义(P<0.05)。400μg/L与200μg/L组相比其MDR1/P-gp抑制程度并不明显,其余各组间差异均有统计学意义(P<0.05)。结论 TRAIL可抑制SGC-7901/VCR MDR1/P-gp的表达,且呈量效关系。TRAIL可能通过降低耐药基因MDR1的表达逆转胃癌的多药耐药。     

Reversal of P-glycoprotein-mediated multidrug resistance in SGC7901/VCR cells by PPARγ activation by troglitazone

Over-expression of P-glycoprotein(P-gp),an ATP-dependent drug efflux pump,represents one of the major mechanisms that contribute to multidrug resistance(MDR) in cancer cells.This study examined the effects of troglitazone,a ligand of peroxisome proliferator-activated receptor gamma(PPARγ),on P-gp-mediated MDR in SGC7901/VCR cells(a vincristine-resistant human gastric cancer cell line).The expression of P-gp was detected by RT-PCR and Western blotting,respectively.The SGC7901/VCR cells were treated with 0.1 ...     

粉防己碱逆转P-gp介导的膀胱肿瘤多药耐药的实验研究

目的　观察粉防己碱 (Tetrandrine)对多药耐受糖蛋白 (P - glycoprotein ,P - gp)介导的膀胱癌细胞多药耐药 (MDR)的逆转。方法　MTT法观察MDR的逆转 ,流式细胞仪检测细胞内罗丹明 - 12 3浓度。结果　粉防己碱组与对照组对敏感株的细胞毒作用无显著差异 (P >0 .0 5 ) ;耐药株对粉防己碱组的敏感性是对照组的 4 .6倍 (P <0 .0 5 ) ,粉防己碱明显抑制了细胞内Rh - 12 3的外排 (P <0 .0 5 )。结论　粉防己碱可有效逆转P - gp介导的MDR。     

P糖蛋白在乳腺癌原发性耐药过程中的表达

目的:研究乳腺癌原发性耐药过程中P糖蛋白(Pglycoprotein,P-gp)的表达特征,初步探讨乳腺癌原发性耐药的发生机制.方法:采用免疫组织化学及逆转录多聚酶链反应技术,对25例接受术前新辅助化疗的乳腺癌患者、15例未接受术前化疗的乳腺癌患者、10例乳腺腺病患者组织标本内P-gp和MDR1 mRNA的表达情况进行检测.结果:P-gp表达阳性率在乳腺癌术前化疗组患者和未化疗组患者中分别为84.0%(21/25)和46.7%(7/15),对照组未见P-gp表达;MDR1表达阳性率在三组则分别为84.0%(21/25)、53.3%(8/15)和10%(1/10),组间差异均显著(P＜0.01).结论:部分乳腺癌细胞在恶性变的过程中同时伴有对化疗药物耐受能力的增加,肿瘤细胞内极低水平的MDR1 mRNA表达即可导致多药耐药,MDR1/P-gp与乳腺癌的内源性耐药相关.     

Reversal effect of bufalin on multidrug resistance in K562/VCR vincristine-resistant leukemia cell line

ObjectiveTo probe insights into the reversal effect of bufalin on vincristine-acquired multidrug resistance (MDR) in human leukemia cell line K562/VCR.MethodsProliferative inhibition rate and the reversal index (RI) of bufalin were determined by Methyl thiazolyl tetrazolium assay. The uptake of Adriamycin (ADM) in K562/VCR cells, cell cycle and apoptosis rate were determined by flow cytometry (FCM). Cell morphologic changes were observed with Wright-Giemsa staining. The expression of P-glycoprotein (P-gp), multidrug-associated protein-1 (MRP1), Bcl-xL and Bax protein were measured by immunocytochemistry.ResultsThe human leukemia multidrug resistant K562/VCR cells showed no cross-resistance to bufalin. The RIs of bufalin at concentrations of 0.0002, 0.001 and 0.005 μmol/L were 4.85, 6.94 and 14.77, respectively. Preincubation of 0.001 μmol/L bufalin for 2 h could increase intracellular ADM fluorescence intensity to 28.07% (P<0.05) and down-regulate MRP1 expression simultaneously, but no remarkable effect was found on P-gp protein. Cell cycle analysis indicated increased apoptosis rate and apparent decreased G2/M phase proportion after treatment with bufalin. When exposed to 0.01 μmol/L bufalin, typical morphological changes of apoptosis could be observed. Down-regulation of Bcl-xL and up-regulation of Bax expression in K562/VCR cells could be detected by immunocytochemistry.ConclusionBufalin could partly reverse the MDR of K562/VCR cells, with a possible mechanism of down-regulating MRP1 expression and activating apoptosis pathway by altering Bcl-xL/Bax ratio.     

Reversal of MDR1 gene-dependent multidrug resistance using short hairpin RNA expression vectors

Background RNA interference using short hairpin RNA (shRNA) can mediate sequence-specific inhibition of gene expression in mammalian cells. A vector-based approach for synthesizing shRNA has been developed recently. Overexpression of P-glycoprotein (P-gp), the MDR1 gene product, confers multidrug resistance (MDR) to cancer cells. In this study, we reversed MDR using shRNA expression vectors in a multidrug-resistant human breast cancer cell line (MCF-7/AdrR). Methods The two shRNA expression vectors were constructed and introduced into MCF-7/AdrR cells. Expression of MDR1 mRNA was assessed by RT-PCR, and P-gp expression was determined by Western Blot and immunocytochemistry. Apoptosis and sensitization of the breast cancer cells to doxorubicin were quantified by flow cytometry and methyl thiazolyl tetrazolium (MTT) assays, respectively. Cellular daunorubicin accumulation was assayed by laser confocal scanning microscopy (LCSM). Statistical significance of differences in mean values was evaluated by Student’s t tests. P&lt;0.05 was considered statistically significant.Results In MCF-7/AdrA cells transfected with MDR1-A and MDR1-B shRNA expression vectors, RT-PCR showed that MDR1 mRNA expression was reduced by 40.9% (P&lt;0.05), 30.1% (P&lt;0.01) (transient transfection) and 37.6 % (P&lt;0.05), 28.0% (P&lt;0.01) (stable transfection), respectively. Western Blot and immunocytochemistry showed that P-gp expression was significantly and specifically inhibited. Resistance against doxorubicin was decreased from 162-fold to 109-fold (P&lt;0.05), 54-fold (P&lt;0.01) (transient transfection) and to 108-fold (P&lt;0.05), 50-fold (P&lt;0.01) (stable transfection). Furthermore, shRNA vectors significantly enhanced the cellular daunorubicin accumulation. The combination of shRNA vectors and doxorubicin significantly induced apoptosis in MCF-7/AdrR cells. Conclusions shRNA expression vectors effectively reduce MDR expression in a sustained fashion and can restore the sensitivity of drug-resistant cancer cells to conventional chemotherapeutic agents.     

健脾解毒方可通过COX-2通路逆转大肠癌细胞P-糖蛋白介导的多重耐药性

Objective:To evaluate the underlying mechanism of Jianpi Jiedu Recipe(健脾解毒方,JJR)in the reversion of multidrug resistance concerning colorectal cancer in vitro and in vivo.Methods:Mice were treated orally with JJR at a daily 4.25 g/(kg-day)or injected with vinblastine(VCR)2.5 mg/(kg·day)for 3 weeks after having been inoculated with HCT8/V cells;tumor tissues were assayed by hematoxylin and eosin staining.Firstly,the effects of JJR on the expression of cyclooxygenase-2(COX-2)were tested by real-time polymerase chain reaction(PCR)technique and COX-2 gene silenced by siRNA.Secondly,the variation of intracellular concentration of oxaliplatin(L-OHP)was evaluated by the inductively coupled plasma mass spectroscopy(ICPMS)in HCT8/V and its COX-2 siRNA cells;the concentration of JJR combined with chemotherapeutic drugs and the reverse effect of multidrug resistance(MDR)in HCT8/V cells was evaluated by the MTT assay.Thirdly,real-time quantitative PCR and Western blot analysis were used to detect the multidrug resistance gene 1(MDR1)mRNA and P-gp expression.Results:JJR had an inhibitory effect on the growth of tumors in vivo,and it,in combination with chemotherapeutic drugs,could reverse the drug-resistance of HCT8/V cells and increase the sensitivity of HCT8/V cells to VCR,DDP,5-Fu,and THP.ICP-MS results showed that JJR could increase the concentration of drugs in HCT8/V cells(P0.01).Furthermore,it was shown that JJR could reverse drug resistance of colorectal cancer cells by decreasing MDR1 expression and P-gp level via downregulation of COX-2,which has been represented as one of the major mechanisms that contributes to the MDR phenotype(P0.01).Conclusion:JJR reversed multidrug resistance and enhanced the sensitivity to chemotherapy,which could be attributed to the down-regulation of COX-2 in MDR1/P-gp-mediated MDR colorectal cancer after chemotherapy.     

白血病耐药细胞中多药耐药基因MDR1与核转录因子κB的关系

目的:研究核转录因子κB与多药耐药基因MDR1在白血病化疗耐药中的作用,阐明核转录因子κB(NF-κB)与白血病多药耐药的关系及相关分子机制。方法：白血病细胞K562和阿霉素(ADM)诱导的耐药细胞K562/ADM分别应用ADM（0、0.25、0.50、1.00和2.00 μg·L^-1）或丝裂霉素(MIT)（0、2、4、8和16 mg·L^-1）　作用48 h,通过MTT法检测细胞生存率,计算细胞耐药指数;RT-PCR方法检测MDR1和IκB mRNA表达;Western blotting方法检测P-gp和P65的蛋白表达。结果：ADM和MIT分别作用后,与空白对照组比较,白血病细胞K562细胞生存率下降(P<0.01),呈剂量依赖性;ADM和MIT对耐药细胞K562/ADM生存率作用不明显;在mRNA水平上,与K562细胞比较,K562/ADM细胞的MDR1 mRNA高表达(P<0.01)。与空白对照组比较,ADM 0.50和1.00　 μg·L^-1>或MIT 4和8 mg·L^-1分别作用K562细胞和K562/ADM细胞,IκBα mRNA表达均下降(P<0.01),并呈剂量依赖性;在蛋白水平上,与K562细胞比较,K562/ADM细胞的P-gp蛋白高表达(P<0.01)。与空白对照组比较,ADM 0.50和1.00 μg·L^-1或MIT 4和8 mg·L^-1分别作用K562/ADM细胞,P-gp蛋白表达量升高(P<0.01),同时P65蛋白表达量升高,且呈药物剂量依赖性(P<0.01)。结论：MDR1基因及P-gp蛋白的高表达很可能是白血病细胞K562多药耐药性形成的关键机制,而NF-κB的激活可能参与了多药耐药的调控。