低频率超声对MCF-7/DOX细胞多药耐药逆转的体外研究*

目的:观察低频率超声空化效应对人乳腺癌细胞株MCF-7/DOX 多药耐药的逆转作用,并探讨其逆转肿瘤多药耐药的机制。方法:以不同的超声辐射时间照射MCF-7/S 、MCF-7/DOX 细胞,采用MTT 法筛选出非细胞毒剂量的超声照射时间。以无毒剂量的超声照射联合不同浓度的DOX,比较单独DOX组与联合组MCF-7/DOX 细胞对DOX的IC 50值有无明显差异,从而判断低频率超声的增敏作用,并计算增敏倍数和相对逆转效率。用流式细胞仪检测细胞凋亡、细胞内阿霉素的浓度。结果:低频率超声辐射对MCF-7/DOX 细胞具有一定的细胞毒作用,其非细胞毒辐射时间是10s。非细胞毒性的超声辐射可显著增加阿霉素对MCF-7/DOX 细胞的抑制率（从21.65%±0.05% 升至43.13%±0.19%）,可显著降低阿霉素对MCF-7/DOX 细胞的IC 50 （从61.08± 0.27μg/mL降至 28.12± 5.94μ g/mL）;对MCF-7 细胞的抑制率（从66.47% ± 0.02%升至 67.25% ± 0.20%）及IC 50 （从0.84± 0.07μ g/mL 降至 0.802 ±0.03μ g/mL）无明显的影响。低频率超声对MCF-7/DOX 细胞的逆转倍数为2.17倍,相对逆转效率为:54.71% 。流式细胞仪检测结果显示:单独应用DOX,MCF-7 细胞的凋亡率为33.99% ,MCF-7/DOX 细胞的凋亡率为4.4% ,低频率超声与DOX合用后,MCF-7/DOX凋亡率为13.70% 。低频率超声处理后,MCF-7/DOX 细胞内DOX浓度显著增加,峰值明显右移,但尚不能达到敏感细胞的水平。结论:低频率超声可部分逆转人乳腺癌MCF-7/DOX 细胞对阿霉素的耐药性,其逆转机制考虑为低频率超声空化效应增加细胞膜的通透性,增加肿瘤细胞内抗肿瘤药物的浓度,从而杀灭耐药的肿瘤细胞,逆转肿瘤耐药性。      

环孢素A对白血病耐药细胞化疗药物敏感性的研究

目的 研究环孢素A对K562/DOX细胞多药耐药的逆转作用.方法 用流式细胞仪和MTT法观察了CsA对K562/DOX细胞P-糖蛋白的抑制作用及对阿霉素(doxorubicin,DOX)、长春新碱(vincristine,VCR)耐药的逆转作用.结果 CsA能剂量相关性地增加K562/DOX细胞内罗丹明123(rhodamine123,Rh123)的累积,明显抑制P-gp介导的Rh123外排,显著增强DOX、VCR的细胞毒作用,增加VCR诱导的细胞凋亡和G2/M期细胞百分率.结论 CsA能显著抑制P-gp的外排功能,逆转K562/DOX细胞的多药耐药性.     

汉防己甲素逆转白血病细胞株K562/ADM多药耐药性机制研究

目的 研究汉防己甲素(TTD)对慢性粒细胞白血病急性变白血病细胞株K562／ADM多药耐药(MDR)逆转的机理。方法 采用流式细胞仪检测细胞内化疗药物的浓度及细胞表面P糖蛋白(P-gp)的表达；荧光定量PCR法检测MDR1 mRNA；通过流式细胞仪检测Anexin—V判断凋亡细胞的数量。结果 10μmol/L的TTD处理K562／ADM细胞后，细胞内阿霉素(ADM)的浓度明显提高；K562／ADM细胞MDR1 mRNA／P-gp的表达下降；TTD能增强ADM致细胞凋亡的作用。结论 汉防己甲素的耐药逆转机制除了下调MDR1 mRNA／P-gp的表达引起细胞内抗癌药物的积聚外，增加抗癌药物致细胞凋亡也是耐药逆转的重要原因。．     

川芎嗪联合三氧化二砷逆转K562/ADM细胞多药耐药的实验研究

目的探讨川芎嗪与三氧化二砷联合逆转耐药人红白血病细胞株K562/ADM多药耐药的效果。方法采用WST-8法测定细胞的药敏性及抗药性逆转,应用流式细胞术检测细胞凋亡、细胞内ADM浓度、P-gp蛋白的表达,采用免疫细胞化学二步法检测细胞GST-π表达。结果非细胞毒性浓度的TMP（20μg/ml）及As2O3（0.5μmol/L）可降低ADM对K562/ADM细胞的IC50（P〈0.05）,2种药物联合应用对ADM的逆转倍数明显高于两者单独应用（P〈0.05）,而且也高于两者单独应用之和;两者以非细胞毒性浓度联合应用提高K562/ADM细胞内ADM浓度和细胞凋亡百分率,作用大于两药单独应用,并且明显下调细胞P-gp和GST-π表达（P〈0.05,P〈0.01）。结论非细胞毒性剂量的TMP和As2O3,均可部分逆转有多药耐药表型的细胞株K562/ADM对阿霉素的耐药性,两者联合应用效果优于单独应用,具有协同作用,其机制可能与下调P-gp和GST-π表达有关。     

Gleevec耐药白血病细胞中P-糖蛋白功能失调及其调节

目的：明确Pgp在Gleevec耐药白血病细胞中的表达和功能,为临床合理用药提供理论指导。方法：四甲基偶氮唑盐（MTT）法检测K562/G01细胞对阿霉素（Doxorubicin,DOX）和伊马替尼（Gleevec,STI571）细胞毒作用的敏感性以及Pgp抑制剂维拉帕米（Verapamil,VPL）对K562/G01细胞药物敏感性的调节作用;RT-PCR和Western-blotting方法检测细胞中MDR基因mdr1及Pgp的表达;流式细胞仪（Flow cytometry,FCM）检测细胞内DOX及罗丹明123（Rhodamin123,Rho123）水平以及Gleevec和ATP对Pgp功能的调节作用。结果：人白血病Gleevec耐药K562/G01细胞对Gleevec耐药约40倍,但对MDR类化疗药物DOX却保持敏感,而且,Pgp抑制剂VPL不改变K562/G01细胞对DOX的敏感性。与MDR表型的K562/A02细胞一样,K562/G01细胞表达mdr1及其编码的Pgp蛋白,但Pgp却没有药物外排泵功能,K562/G01细胞中DOX或Rh123浓度与敏感细胞K562相当。加入Gleevec或ATP可明显降低K562/G01细胞中DOX水平。结论：人白血病Gleevec耐药细胞K562/G01表达mdr1/Pgp,但Pgp功能明显受阻,Bcr/Abl抑制剂Gleevec或ATP可部分恢复K562/G01细胞中Pgp的药物外排泵功能。     

5-溴汉防己甲素与汉防己甲素对K562/A02细胞多药耐药性逆转作用的比较

背景与目的:5-溴汉防己甲素(5-bromotetrandrine,BrTet)是汉防己甲素(tetrandrine,Tet)的溴化产物,具有逆转P-糖蛋白(P-glyeoprotein,P-gp)介导的肿瘤多药耐药(muhidrug resistance,MDR)的作用。本研究旨在比较BrTet与Tet对人白血病细胞K562/A02多药耐药的逆转作用。方法:采用四甲基偶氮唑蓝法(MTT)法检测不同浓度BrTet对K562细胞和K562/A02细胞的增殖抑制效应;检测阿霉素(adfiamycin,ADM)对K562细胞和K562/A02细胞增殖的抑制作用,以及加用BrTet、Tet时上述抑制作用的变化,并计算半数抑制浓度(IC50)及逆转倍数。Westernblot法检测各组细胞P-gp的表达,流式细胞仪检测各组细胞内ADM的蓄积。结果:K562/A02细胞对ADM的耐药倍数为49.51倍。2.0μmol/L及更低浓度的BrTet和1.5μmol/L及更低浓度的Tet对K562细胞和K562/A02细胞抑制率均小于10%,无明显细胞毒性作用。加入1.0μmol/L的Tet后,K562/A02细胞对ADM的耐药倍数为12.17倍。加入0.25、0.5和1.0μmol/L的BrTet后,K562/A02细胞对ADM的耐药倍数分别为17.88、9.97和4.24倍。1.0"mol/L的BrTet和Tet分别使K562/A02细胞内ADM浓度提高了69.0%和51.6%,使P-gp表达分别下调了51.1%和43.73%,其差异具有统计学意义(P<0.05)。结论:BrTet及Tet均可逆转K562/A02细胞耐药,且前者较后者逆转作用更强,逆转机制与抑制P-gp的表达、增加细胞内抗肿瘤药物浓度有关。     

PSC833逆转人骨肉瘤细胞株多药耐药性的研究

目的 探讨PSC 833对骨肉瘤耐药细胞株U2OS/DOX的逆转作用及其机制。方法 用MTT法进行PSC 833逆转MDR活性测定;用流式细胞仪技术，观察PSC833对细胞内Rh123积聚和外排的影响；用免疫荧光技术定量检测逆转剂对P-gp表达水平的影响。结果 PSC833能显著增加DOX对U2OS/DOX的细胞毒性作用，逆转效果明显强于VPL和 CSA，且存在剂量依赖关系,对敏感株U2OS无明显作用；PSC 833能使耐药株细胞内Rh123外排减少、积聚增加，而对P-gp的表达水平没有明显影响。结论 PSC833能增强DOX对U2OS/DOX的细胞毒性作用，逆转MDR效果明显优于VPL和CSA，其机理在于抑制耐药株细胞膜上P-gp的功能，而对P-gp的表达水平没有影响。     

阿帕替尼逆转P-gp转运体介导的乳腺癌化疗多药耐药性的作用及其机制

目的 探讨阿帕替尼对人乳腺癌化疗多药耐药性的逆转作用及其机制。方法 不同浓度的阿帕替尼作用于体外培养的人乳腺癌MCF-7及MCF-7/ADR细胞48 h,MTT法检测阿帕替尼对两种细胞的细胞毒性;低毒浓度的阿帕替尼与化疗药物紫杉醇及阿霉素联用,探讨阿帕替尼对两种细胞化疗耐药性的影响;采用流式细胞术检测阿帕替尼对罗丹明123在MCF-7及MCF-7/ADR细胞内蓄积的影响;采用Pgp-Glo? Assay Systems试剂盒观察阿帕替尼对多药耐药相关蛋白P-gp的ATPase活性的影响;采用Western blot法检测阿帕替尼对P-gp表达及AKT磷酸化的影响。结果 阿帕替尼可浓度依赖性地逆转乳腺癌MCF-7/ADR细胞对紫杉醇及阿霉素的多药耐药性（P<0.05）、增加罗丹明123在MCF-7/ADR细胞内的蓄积（P<0.05）及激活P-gp转运体的ATPase活性（P<0.05）,而对P-gp的表达没有影响;此外,阿帕替尼不改变AKT的磷酸化水平。结论 阿帕替尼可能通过抑制P-gp转运体的外排功能逆转P-gp转运体介导的乳腺癌化疗多药耐药性。     

PSC833逆转人骨肉瘤细胞系多药耐药性的研究

目的 探讨PSC833对骨肉瘤耐药细胞系U2OS/DOX和SaOS/DOX的逆转作用及其机制。方法 用MTT法和细胞计数法测定PSC833逆转MDR的活性;用流式细胞仪观察PSC833对细胞内Rh123积聚和外排的影响;用免疫荧光技术定量检测逆转剂对P-gp表达水平的影响。结果 PSC833对DOX敏感系U2OS和SaOS无明显作用。PSC833能显著增加DOX对U2OS/DOX和SaOS/DOX的细胞毒性作用,逆转效果明显强于VPL和CSA,且存在剂量依赖关系。PSC833能减少耐药细胞系内Rh123的外排,增加Rh123的积聚,而对P-gp的表达水平没有明显影响。结论 PSC833能逆转U2OS/DOX和SaOS/DOX的MDR,其效果明显优于VPL和CSA,逆转机理在于抑制耐药系细胞膜上P-gp的功能,而对P-gp的表达水平没有影响。     

马钱子碱对白血病K562/A02细胞多药耐药性的逆转作用

目的：研究马钱子碱（vauqueline）对人白血病K562/A02细胞多药耐药性的逆转作用。方法：采用噻唑蓝（MTT）法检测马钱子碱的细胞毒作用;采用半定量逆转录聚合酶链反应（RT-PCR）和免疫印迹（Western blot）分别检测非细胞毒浓度（IC10）的马钱子碱对K562/A02细胞MDR1 （multidrug resistance gene 1）、多药耐药相关蛋白（multidrug resistance-associated protein,MRP）、拓扑异构酶Ⅱ（topoisomeraseⅡ,TopoⅡ）、谷胱苷肽-S-转移酶（glutathione s-transferase,GST-π）mRNA及其蛋白表达的影响。结果：非细胞毒浓度（IC10）的马钱子碱作用后,K562/A02细胞中MDR1mRNA及P-gp表达降低（P<0.01）。而MRP、TopoⅡ、GST-π mRNA及其蛋白的表达无明显变化（P>0.05）,同时马钱子碱能增加化疗药物在白血病细胞内的积累。结论：马钱子碱能部分逆转K562/A02细胞的耐药性,其作用机制可能与下调K562/A02细胞MDR1 mRNA的表达,导致细胞膜上P-gp的表达量减少,化疗药物从细胞内溢出减少有关。     

FG020327逆转肿瘤多药耐药性的作用及其机制

背景与目的肿瘤细胞过量表达P鄄糖蛋白穴P-glycoprotein.P-gp雪导致多药耐药穴multidrug resistance,MDR雪是目前肿瘤化疗的一大障碍,使用多药耐药逆转剂与抗癌药物联合化疗是克服临床多药耐药的重要方法。本研究对一种新的多芳基取代咪唑化合物FG020327的体外逆转活性及其逆转机制进行了探讨。方法以MTT法检测FG020327对多药耐药肿瘤细胞MCF-7/ADR及KBv200的耐药逆转活性;以荧光分光光度计法检测FG020327对MCF-7/ADR细胞内抗癌药物阿霉素累积的影响;以罗丹明蓄积实验检测该化合物对P-gp功能的影响。结果FG020327在体外具有较强的逆转活性,在5μmol/L浓度下使多药耐药细胞KBv200对长春新碱的敏感性增加44.9倍,逆转活性是公认的强逆转剂维拉帕米的3倍熏但它对敏感株对抗癌药物的敏感性基本无影响。2.5、5和10μmol/L的FG020327使MCF-7/ADR细胞中阿霉素的累积分别增加2.3、2.7和3.7倍,但是在敏感株MCF鄄7细胞却观察不到阿霉素累积的增加。FG020327浓度依赖性增加KBv200细胞内的罗丹明蓄积,但对敏感株KB细胞内的罗丹明蓄积无影响。结论FG020327具有较强的体外逆转MDR的活性,它可能通过抑制P鄄gp功能及增加MDR细胞内抗癌药物的累积逆转MDR。     

The synergistic reversal effect of multidrug resistance by quercetin and hyperthermia in doxorubicin-resistant human myelogenous leukemia cells

Purpose: This study aimed to evaluate the multidrug resistance (MDR) reversal activity of quercetin (Que) in combination with hyperthermia (HT) in human myelogenous leukemia cells K562/A.

Methods: The cytotoxicity of Que alone and the effect of Que and HT to doxorubicin (Dox) cytotoxicity were determined using MTT assay in K562 and K562/A cells. K562/A cells was heated with or without Que pretreatment, and the protein and mRNA levels of heat shock protein 70 (HSP70) and P-glycoprotein (P-gp) were determined by flow cytometry (FCM) and RT-PCR, respectively. Intracellular accumulation of Dox, cell cycle and apoptosis were monitored with FCM.

Results: Que alone inhibited cell growth in a dose-dependent manner in K562 and K562/A cells. Either Que or HT alone had a weak reversal effect on Dox resistance, however, combination HT and Que showed a much more significant reversal effect on Dox resistance (reverse fold 9.49). The elevated protein expression and mRNA level of HSP70 and P-gp in response to HT were inhibited by Que. Pretreatment with Que caused the cells to accumulate Dox 8.3-fold higher than in control cells. In addition, Que induced apoptosis and G2/M arrest in a dose-dependent manner, and the combination of Que and HT was found to have a synergistic efeect on apoptosis.

Conclusions: Que pretreatment could significantly inhance the MDR reversal activity of HT in resistant cell line, by sensitizing the cell to reversing MDR activity of HT.     

The synergistic reversal effect of multidrug resistance by quercetin and hyperthermia in doxorubicin-resistant human myelogenous leukemia cells

PURPOSE: This study aimed to evaluate the multidrug resistance (MDR) reversal activity of quercetin (Que) in combination with hyperthermia (HT) in human myelogenous leukemia cells K562/A. METHODS: The cytotoxicity of Que alone and the effect of Que and HT to doxorubicin (Dox) cytotoxicity were determined using MTT assay in K562 and K562/A cells. K562/A cells was heated with or without Que pretreatment, and the protein and mRNA levels of heat shock protein 70 (HSP70) and P-glycoprotein (P-gp) were determined by flow cytometry (FCM) and RT-PCR, respectively. Intracellular accumulation of Dox, cell cycle and apoptosis were monitored with FCM. RESULTS: Que alone inhibited cell growth in a dose-dependent manner in K562 and K562/A cells. Either Que or HT alone had a weak reversal effect on Dox resistance, however, combination HT and Que showed a much more significant reversal effect on Dox resistance (reverse fold 9.49). The elevated protein expression and mRNA level of HSP70 and P-gp in response to HT were inhibited by Que. Pretreatment with Que caused the cells to accumulate Dox 8.3-fold higher than in control cells. In addition, Que induced apoptosis and G2/M arrest in a dose-dependent manner, and the combination of Que and HT was found to have a synergistic effect on apoptosis. CONCLUSIONS: Que pretreatment could significantly enhance the MDR reversal activity of HT in resistant cell line, by sensitizing the cell to reversing MDR activity of HT.     

Modulation of resistance to idarubicin by the cyclosporin PSC 833 (valspodar) in multidrug-resistant cells

Idarubicin (IDA) is an anthracycline anticancer drug utilized in the treatment of acute leukemias. There are conflicting data published with regard to the cross-resistance of IDA in multidrug-resistant (MDR) cells expressing P-glycoprotein (P-gp). We evaluated the cytotoxicity and cellular accumulation of IDA in a panel of anthracycline-selected MDR cell lines. Leukemia K562/R7 cells and sarcoma MES-SA/Dx5 cells expressing high levels of the MDR1 (ABCB1) gene were resistant to IDA (42-fold and 150-fold, respectively). In both of these cell lines, resistance to IDA was equivalent to that for doxorubicin, the drug used to select for the MDR variants. The P-gp inhibitor PSC 833 (valspodar) at 2 microM completely restored sensitivity to IDA. IDA accumulation was decreased 12-fold in MES-SA/Dx5 cells vs parental cell line, and drug uptake was restored to control levels by PSC 833. Reduced intracellular IDA was correlated with P-gp content by flow cytometry. Experiments in NIH3T3 murine cells transfected with the human MDR1 gene substantiated the findings of cross-resistance to IDA and reversal of resistance by PSC 833. Our data indicate that IDA is a high-affinity substrate for P-gp.     

MDR1基因短发卡样RNA表达载体逆转K562/A02人白血病细胞多药耐药的研究

目的构建MDR1基因短发卡样RNA(shRNA)真核表达载体,观察对K562/A02人白血病细胞株MDR1基因的沉默作用以及对P-糖蛋白(P-gp)表达及功能的影响。方法以基因重组技术构建表达质粒,转染重组质粒pEGFP-C1/U6/MDR1-A和pEGFP-C1/U6/MDR1-B至K562/A02细胞株,通过半定量RT-PCR和蛋白质印迹法,检测MDR1基因表达及P-gp表达水平的变化;以MTT法检测阿霉素(ADM)对K562/A02细胞的半数抑制浓度(IC_(50));高效液相色谱(HPLC)法检测细胞内ADM含量。结果构建的2种重组质粒pEGFP-C1/U6/MDR1-A和pEGFP-C1/U6/MDR1-B均明显抑制K562/A02细胞株MDR1基因表达,抑制率最高为48．2%±2．5%;同时抑制P-gp蛋白的表达,抑制率最高为50．67%。对ADM药物敏感性的相对逆转效率分别为40．8%和62．4%;同时使K562/ A02细胞内ADM含量增加。结论shRNA表达载体可明显抑制K562/A02细胞MDR1 mRNA的转录和P-gp蛋白的表达,增加K562/A02细胞内ADM含量,恢复K562/A02细胞对化疗药物的敏感性,逆转MDR1基因编码蛋白P-gp介导的多药耐药。     

Screening novel, potent multidrug-resistant modulators from imidazole derivatives

The overexpression of P-glycoprotein (P-gp) by tumor cells results in multidrug resistance (MDR) to structurally unrelated anticancer drugs. Combined therapy with MDR-related cytotoxins and MDR modulators is a promising strategy to overcome clinical MDR. This study was designed to screen potent MDR modulators from imidazole derivatives. Cytotoxicity was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The intracellular accumulation of doxorubicin (Dox) was detected by fluorescence spectrophotometry. The function of P-gp was examined by Rhodamine 123 accumulation detected with flow cytometry (FCM). Among imidazole derivatives, FG020326, FG020327, and FG020318 were found to possess three- to fourfold stronger reversal MDR activity than verapamil, a well-known positive MDR modulator. Imidazole derivatives significantly increased the Dox accumulation and inhibited P-gp function exhibited by the increase of Rhodamine accumulation in MDR cells. The fold reversal of MDR was relative with the increase of Rhodamine accumulation. FG020326, FG020327, and FG020318 showed potent MDR reversal activity in vitro. Their mechanism of MDR reversal is associated with the inhibition of P-gp function and the increase of anticancer accumulation. These results suggest FG020326, FG020327, and FG020318 are promising to further study and develop.