Reversal of multidrug resistance by co-delivery of tariquidar (XR9576) and paclitaxel using long-circulating liposomes

One of the major obstacles to the success of cancer chemotherapy is the multidrug resistance (MDR) often resulting due to the overexpression of drug efflux transporter pumps such as P-glycoprotein (P-gp). Highly efficacious third generation P-gp inhibitors, like tariquidar, have shown promising results in overcoming the MDR. However, P-gp is also expressed in normal tissues like blood brain barrier, gastrointestinal track, liver, spleen and kidney. To maximize the efficacy of P-gp inhibitor and reduce the systemic toxicity, it is important to limit the exposure of P-gp inhibitors and the anticancer drugs to normal tissues and increase their co-localization with tumor cells. In this study, we have investigated the co-delivery of the P-gp inhibitor, tariquidar, and cytotoxic drug, paclitaxel, into tumor cells to reverse the MDR using long-circulating liposomes. Tariquidar- and paclitaxel-loaded long-circulating liposomes showed significant resensitization of the resistant variant for paclitaxel, which could be correlated with an increased accumulation of paclitaxel in tumor cells. These results suggest that the co-delivery of the P-gp inhibitor, tariquidar, and the cytotoxicity inducer, paclitaxel, looks like a promising approach to overcome the MDR.     

PEG-PE-based micelles co-loaded with paclitaxel and cyclosporine A or loaded with paclitaxel and targeted by anticancer antibody overcome drug resistance in cancer cells

The over-expression of the P-glycoprotein (P-gp) in cancer cells is one of the main reasons of the acquired Multidrug Resistance (MDR). Combined treatment of MDR cancer cells with P-gp inhibitors and chemotherapeutic agents could result in reversal of resistance in P-gp-expressing cells. In this study, paclitaxel (PTX) was co-encapsulated in actively targeted (anticancer mAb 2C5-modified) polymeric lipid-core PEG-PE-based micelles with Cyclosporine A (CycA), which is one of the most effective first generation P-gp inhibitors. Cell culture studies performed using MDCKII (parental and MDR1) cell lines to investigate the potential MDR reversal effect of the formulations. The average size of both empty and loaded PEG₂₀₀₀-PE/Vitamin E mixed micelles was found between 10 and 25 nm. Zeta potentials of the formulations were found between ?7 and ?35 mV. The percentage of PTX in the micelles was found higher than 3% for both formulations and cumulative PTX release of about 70% was demonstrated. P-gp inhibition with CycA caused an increase in the cytotoxicity of PTX. Dual-loaded micelles demonstrated significantly higher cytotoxicity in the resistant MDCKII-MDR1 cells than micelles loaded with PTX alone. Micelle modification with mAb 2C5 results in the highest cytotoxicity against resistant cells, with or without P-gp modulator, probably because of better internalization bypassing the P-gp mechanism. Our results suggest that micelles delivering a combination of P-gp modulator and anticancer drug or micelles loaded with only PTX, but targeted with mAb 2C5 represent a promising approach to overcome drug resistance in cancer cells.     

Improved cytotoxicity and multidrug resistance reversal of chitosan based polymeric micelles encapsulating oxaliplatin

To overcome the side effects and drug resistance in cancer chemotherapy, oxaliplatin (OXA) was encapsulated in chitosan based polymeric micelles with glycolipid-like structure, which were formed by stearic acid-grafted chitosan oligosaccharide (CSO-SA). CSO-SA with 6.89% amino substituted degree was synthesized in this paper. The critical micelle concentration was about 0.12?mg/mL. CSO-SA micelles with the concentration of 1.0?mg/mL had 34.8?nm number average diameter and +50.8 mV surface potential in the aqueous medium. Thin-film dispersed method mediated by lecithin was chosen to prepare OXA-loaded CSO-SA micelles (CSO-SA/OXA), encapsulation efficiency of which could reach up to about 47%. In vitro anti-tumor activity of CSO-SA/OXA micelles against drug sensitive tumor cells and drug resistant cells was then examined. Using SGC-7901, SKOV3, BEL-7402, K562, and MCF-7 as model drug sensitive tumor cells, the 50% inhibition of cellular growth (IC₅₀) of CSO-SA/OXA micelles could be lowered about 3-6 folds compared to that of free OXA solution. Furthermore, cytotoxicity test of CSO-SA/OXA micelles against MCF-7 and multidrug resistant MCF-7 (MCF-7/Adr) cells presented the reversal activity against MCF-7/Adr cells. The present micelles are a promising carrier candidate for platinum drug to improve the anti-tumor activity.     

Long-circulating PEG-PE micelles co-loaded with paclitaxel and elacridar (GG918) overcome multidrug resistance

Overexpression of drug efflux pump P-gp is one of the major reasons to cause multidrug resistance (MDR). To overcome P-gp mediated MDR, modulators, so called P-gp inhibitors, can be used to block efflux pump activity. Elacridar is one of the most potent P-gp inhibitors, which can cause irreversible and total P-gp blockage. Elacridar, among with other P-gp inhibitors, can be used in combination with anticancer drugs to enhance the effectiveness of chemotherapy against resistant tumor cells. On the other hand, P-gp is presented in normal tissues, thus non-selective blockage of P-gp can cause undesired side effects. Therefore, it is important to deliver P-gp inhibitor only to the tumor cells (along with anticancer drug) and limit its distribution in the body. In this study, we have developed PEG-PE-based long-circulating ca. 15?nm micelles co-loaded with elacridar and paclitaxel, and investigated their ability to overcome paclitaxel resistance in two cancer cell lines. Vitamin E, a common solubility enhancer for PEG-PE micelles, was found to have a negative effect on both particle size and encapsulation efficiencies. The human MDR1 gene-transfected and thus paclitaxel-resistant MDCKII-MDR1 P-gp overexpressing cells were used for cytotoxicity evaluation. Even though PEG-PE based micelles itself have a potential to enhance the cytotoxicity of paclitaxel, elacridar/paclitaxel-co-loaded micelles demonstrated the highest cytotoxicity compared to both free and micellar paclitaxel. The obtained results suggest that co-loading of paclitaxel and elacridar into micellar drug carriers results in promising preparations capable of overcoming paclitaxel resistance.     

Overcoming multiple drug resistance in cancer using polymeric micelles

ABSTRACT

Introduction: A major concern that limits the success of cancer chemotherapy is multidrug resistance (MDR). The drug resistance mechanisms are either host related or tumor related. The host tumor interacting factors also contribute to MDR. Multifunctional polymeric micelles offer several advantages in circumventing MDR due to their design, selectivity, and stability in cancer microenvironment.

Areas covered: The review is broadly divided into two parts: the first part covers MDR and its mechanisms; the second part covers multifunctional polymeric micelles in combating MDR through its state-of-the-art design. This part covers various strategies like use of P-gp transporter inhibitors, TPGS, pH & thermo-sensitive, and siRNA for selectivity of PMs against multidrug-resistant tumors.

Expert opinion: Numerous approaches have been tested using polymeric micelles to overcome MDR tumors. However, these are either limited to only in-vitro investigations and/or preliminary preclinical models and do not investigate the underlying biological mechanism. Hence, there exists an unmet need to perform fundamental research that focuses on studying the underlying mechanism and preclinical/clinical testing of the micellar formulations.     

肿瘤多药耐药逆转剂的研究进展

肿瘤细胞产生的多药耐药(multidrugresistanceMDR)已成为当前影响肿瘤化学治疗疗效的主要障碍。尽管MDR产生机制复杂,但是由mdr1基因编码的P糖蛋白(PglycoproteinPgp)的过表达是产生MDR的主要原因。寻找低毒有效的MDR逆转剂是提高化疗疗效的一个重要方法,是化疗领域亟需解决的问题。     

维拉帕米逆转肿瘤多药耐药性的研究进展

肿瘤细胞对化疗药物产生的多药耐药（MDR）已成为当前影响肿瘤化学治疗疗效的主要障碍，寻找低毒有效的MDR逆转剂是提高化疗疗效的关键。MDR产生机制复杂，由mdrl基因编码的P-糖蛋白（P-glycoprotein P-gp）的过表达是产生MDR的主要原因。维拉帕米是应用最早的MDR逆转剂之一，但其毒副作用大大限制了临床应用。从维拉帕米分离出的光学异构体R-型维拉帕米，在逆转肿瘤MDR时，更加高效安全，具有良好的临床应用前景。     

Comparison of hyaluronic acid-based micelles and polyethylene glycol-based micelles on reversal of multidrug resistance and enhanced anticancer efficacy in vitro and in vivo

Polyethylene glycol (PEG)-based block copolymer micelles and hyaluronic acid (HA)-based grafted copolymer micelles have been widely investigated in chemotherapy. In this study, to evaluate the differences among HA-based grafted polymer micelles, PEG-based block polymer micelles and the mixed of these two micelles in enhancing antitumor effects and overcoming MDR, two amphiphilic vitamin E succinate (VES) derivatives, HA VES (HA-g-VES) and PEG 2000 VES (TPGS2k), were applied as nanocarriers to prepare HA-VES micelles (HA-PMs), TPGS2k micelles (TPGS2k-PMs) and the mixed micelles (HA/TPGS2k-PMs) for the co-delivery of doxorubicin (DOX) and curcumin (Cur). With the addition of TPGS2k, the particle size of HA/TPGS2k-PMs (153.37?±?1.00?nm) was smaller than that of HA-PMs (223.83?±?1.84) but significantly larger than that of TPGS2k-PMs (about 20?nm). The loading efficiency of HA/TPGS2k-PMs was 7.10%, which was lower than HA-PMs (8.31?±?0.15%) but higher than TPGS2k-PMs (4.38?±?0.24%). In vitro, HA/TPGS2k-PMs and TPGS2k-PMs exhibited higher cytotoxicity and reversal MDR effects than HA-PMs in MCF-7/Adr cells. However, HA/TPGS2k-PMs, HA-PMs and TPGS2k-PMs all significantly improved the tumor biodistribution, the antitumor effects and reduced the side effects of DOX in 4T1-tumor-bearing mice, but these three micelles displayed no differences in vivo. Therefore, EPR passive targeting effects caused by PEGylated micelles and CD44 active targeting effects caused by HA-based micelles have no significant variance in the delivery of antitumor drugs by i.v.     

Overcoming multidrug resistance in human cancer cells by natural compounds

Multidrug resistance is a phenomenon whereby tumors become resistant to structurally unrelated anticancer drugs. P-glycoprotein belongs to the large ATP-binding cassette (ABC) transporter superfamily of membrane transport proteins. P-glycoprotein mediates resistance to various classes of anticancer drugs including vinblastine, daunorubicin, and paclitaxel, by actively extruding the drugs from the cells. The quest for inhibitors of anticancer drug efflux transporters has uncovered natural compounds, including (-)-epigallocatechin gallate, curcumin, capsaicin, and guggulsterone, as promising candidates. In this review, studies on the effects of natural compounds on P-glycoprotein and anticancer drug efflux transporters are summarized.     

白血病细胞多药耐药逆转方法的研究进展

白血病细胞耐药的产生是药物治疗中的一大阻碍,耐药细胞过表达的跨膜转运蛋白（主要为P-糖蛋白）导致胞内药物浓度降低是产生耐药的主要原因。此外,凋亡基因的异常表达、药物作用靶点的改变也产生多药耐药（MDR）。针对这些特点寻找合适的药品与化疗药合用以增加肿瘤细胞对化疗药的敏感性,或者利用高分子材料改变释药系统,以及开发新型药物是逆转白血病细胞耐药的主要手段。通过对逆转白血病MDR的方法进行探讨,旨在为白血病治疗提供新思路。     

Reversal of multidrug resistance in murine fibrosarcoma cells by thioxanthene flupentixol

Summary The purpose of this study was to identify calcium channel and calmodulin antagonists effective in increasing the cytotoxic effects of several chemotherapeutic drugs against UV-2237 murine fibrosarcoma MDR cells. Among 8 compounds tested at nontoxic concentrations, flupentixol, a piperazine-substituted thioxanthene, was the most potent in enhancing the cytotoxicity of anticancer drugs commonly associated with the multidrug resistant (MDR) phenotype, such as Adriamycin, actinomycin D, vinblastine, and vincristine, but not 5-fluorouracil, a drug usually unaffected by MDR. The chemosensitizing effects of flupentixol were produced by increasing intracellular drug accumulation via a mechanism unrelated to the binding of the plasma membrane P-glycoprotein.     

洛美利嗪逆转K562/ADM细胞多药耐药性

目的研究洛美利嗪(lomerizine,Lom)逆转K562/ADM细胞多药耐药性的作用及机制。方法MTT法检测细胞毒作用,流式细胞仪研究Lom对ADM和长春新碱(vincristine,VCR)的K562/ADM细胞凋亡诱导作用的影响及对罗丹明123(rhodamine 123,Rh123)外排和P-糖蛋白(P-glycoprotein,P-gp)表达的作用。结果Lom明显提高ADM对K562/ADM多药耐药细胞的细胞毒作用及ADM和VCR的凋亡诱导作用,3,10和30 μmol·L^-1 Lom使K562/ADM对ADM的IC₅₀值由79.03 μmol·L^-1分别降至28.14,8.16和3.16 μmol·L^-1。Lom增加胞内ADM的蓄积浓度并抑制Rh123外排;但作用72 h后对K562/ADM细胞P-gp表达无影响。结论Lom通过抑制P-gp的活性逆转K562/ADM细胞的多药耐药性。     

黄酮类化合物逆转肿瘤多药耐药作用的研究进展

肿瘤多药耐药是肿瘤治疗过程中一个亟待解决的难题,其表现为肿瘤细胞对单一或多种化疗药物同时出现耐药性,从而导致治疗失败,与药物的化学结构和作用机制无关。将化疗药物与肿瘤多药耐药逆转剂联合应用是目前公认的治疗方案之一。黄酮类化合物由于其低毒、高效,具有多种药理作用等优点而受到广泛的关注。在肿瘤治疗期间,黄酮类化合物能通过抑制ABC转运体、诱导凋亡、调节氧化应激等作用逆转肿瘤多药耐药。归纳总结了黄酮类化合物逆转肿瘤多药耐药的主要机制、应用及其纳米剂型改造的进展,为进一步的临床研究提供参考。     

肿瘤多药耐药逆转剂研究进展

化疗是治疗肿瘤的主要手段之一，多药耐药性的产生是肿瘤化疗中存在的主要问题。开发多药耐药逆转剂，逆转现有化疗药物的耐药性将是一种有效的治疗方法。目前已有多种多药耐药逆转剂处于基础和临床试验阶段。本文对近年来多药耐药逆转剂的研究概况做了简要阐述。     

聚合物胶束递药系统逆转肿瘤多药耐药性的研究进展

聚合物胶束是近年来抗肿瘤药物递药系统研究中发展较快的一种新型递药载体,可显著提高药物抗肿瘤效果,尤其在逆转肿瘤多药耐药现象方面表现出极大的潜在价值。本文主要综述了聚合物胶束递药系统抑制肿瘤多药耐药现象的过程和机制,总结了该领域研究的最新进展,以期为聚合物胶束递药系统今后在该领域的研究提供参考。     

P糖蛋白与配体相互作用的结构基础及其肿瘤耐药逆转的研究

P糖蛋白（P-glycoprotein,P-gp）是一种多药外排转运体,对控制各种抗癌药物的生物学活性具有重要意义。P-gp转运体作为生理屏障阻滞药物渗透,从而使药物发挥效应受限。传统的化疗增敏剂通过对转运体的调节可有效改善抗肿瘤药物的药代动力学并逆转多药耐药。本文将简要概述近年来有关P-gp与配体相互作用的结构信息以及肿瘤耐药逆转策略的研究进展。     

外排型转运体与肿瘤多药耐药

肿瘤多药耐药（MDR）是导致肿瘤化疗失败的主要原因之一。肿瘤MDR的机制有多种,其中外排型转运体的过表达是导致MDR的主要机制,因此研究外排型转运体介导的肿瘤MDR机制和发现可以逆转肿瘤MDR的抑制剂成为国内外研究的热点。就目前研究的3种三磷酸腺苷结合盒转运体：P-糖蛋白、多药耐药相关蛋白、乳腺癌耐药蛋白介导的MDR及逆转MDR的机制进行综述,以期为提高肿瘤治疗疗效提供依据。     

吗丙嗪逆转多药抗药性作用及其分子机制的探讨

目的：探讨吗丙嗪逆转肿瘤多药抗药性（ＭＤＲ）的作用及其机制。方法：以ＭＴＴ与Ｆｕｒａ－２－ＡＭ法进行吗丙嗪逆转ＭＤＲ活性测定；以ＤＰＨ荧光测定法探讨吗丙嗪对膜脂流动性的影响；以荧光分光光度计法测定吗丙嗪与高钙或低钙对细胞内阿霉素（Ｄｏｘ）积累的影响及Ｆｕｒａ－２－ＡＭ法测定吗丙嗪对细胞内游离钙离子浓度的影响。结果：在浓度２．５μｍｏｌ·Ｌ－１时，吗丙嗪能显著增加ＭＣＦ－７／ＡＤＲ细胞内Ｆｕｒａ－２的积累和降低ＭＣＦ－７／ＡＤＲ对Ｄｏｘ的ＩＣ５０而对敏感株ＭＣＦ－７无明显影响，表明吗丙嗪具有逆转ＭＤＲ的作用。吗丙嗪能显著增加ＭＤＲ细胞内Ｄｏｘ积累和降低ＭＤＲ细胞的膜脂流动性。高钙或低钙对ＭＤＲ细胞内Ｄｏｘ积累无影响，吗丙嗪也不能改变１９９７－０４－１１收稿１中山医科大学中心实验室，广州５１００８９作者简介：符立梧，男，３２岁，博士，讲师，主要从事逆转多药抗药性的研究；潘启超，男，６７岁，教授，博士生导师，主要从事肿瘤药理与化疗方面的研究ＭＤＲ细胞内游离钙离子浓度。结论：吗丙嗪有逆转ＭＤＲ作用。其逆转机制与降低膜脂流动性增加细胞内ＤＯＸ积累有关，与钙离子浓度无关     

孕烷X受体与肿瘤多药耐药

多药耐药（MDR）是肿瘤化疗失败的主要原因之一。MDR的产生主要由ATP结合盒（ABC）转运蛋白超家族的跨膜蛋白所引起,其中P-糖蛋白及其编码基因mdr1的过表达是MDR产生的最主要机制。研究MDR的产生机制,寻找诱发mdr1表达的诱因并阻断其表达,是克服肿瘤多药耐药性行之有效的方法。近来研究发现,孕烷X受体（PXR）可介导mdr1的表达,活化的PXR诱导MDR1的表达。因此,特异性地阻断PXR的活化可抑制mdr1的表达,从而克服多药耐药性。现已发现多种物质可作为PXR抑制剂或拮抗剂。本文即对核受体PXR与MDR、PXR抑制剂及拮抗剂的研究现状做一介绍,以期为克服肿瘤多药耐药提供参考。     

紫杉醇诱导的人白血病CCRF-CEM多药耐药细胞模型的建立

目的建立稳定的紫杉醇(paclitaxel)诱导的人肿瘤多药耐药细胞系,并对其生物学特点进行评价。方法用亚致死浓度(1/50IC50值)的紫杉醇连续诱导对化疗药物敏感的人急性T淋巴细胞白血病CCRF-CEM细胞,使其成为对紫杉醇耐药的CCRF-CEM/paclitaxel细胞,同时观察CCRF-CEM/paclitaxel细胞对柔红霉素(daunorubicin)和长春碱(vinblastine)的交叉耐药;用相应的单抗和FITC标记的二抗与细胞孵育后,用流式细胞仪分别检测细胞表面和细胞总P糖蛋白(P-gp)、多药耐药相关蛋白1(MRP1)和肺癌耐药相关蛋白(LRP)等表达水平的变化,并用流式细胞仪检测细胞周期和细胞凋亡率的变化。结果CCRF-CEM/paclitaxel细胞传至第90代时,对紫杉醇产生了耐药,耐药倍数约为256.4倍;同时对柔红霉素和长春碱也产生了耐药,耐药倍数约为9.8和2.0倍。与CCRF-CEM细胞比较,CCRF-CEM/paclitaxel细胞表面P-gp和细胞总P-gp表达分别升高了18.8和14.4倍,MRP1和LRP分别升高了2.1和1.2倍;S期细胞比例由(48.3±1.2)%降低至(23.8±0.5)%,细胞凋亡百分率由(7.82±0.19)%减少至(2.47±0.37)%。结论成功建立了稳定的紫杉醇诱导的人CCRF-CEM/paclitaxel多药耐药细胞模型,该模型具有一般肿瘤多药耐药细胞的生物学特点。