Overcoming multidrug resistance with nanomedicines

Introduction: Cancer remains the leading cause of death worldwide. Numerous therapeutic strategies that include smart biological treatments toward specific cellular pathways are being developed. Yet, inherent and acquired multidrug resistance (MDR) to chemotherapeutic drugs remains the major obstacle in effective cancer treatments.

Areas covered: Herein, we focused on an implementation of nanoscale drug delivery strategies (nanomedicines) to treat tumors that resist MDR. Specifically, we briefly discuss the MDR phenomenon and provide structural and functional characterization of key proteins that account for MDR. We next describe the strategies to target tumors using nanoparticles and provide a mechanistic overview of how changes in the influx:efflux ratio result in overcoming MDR.

Expert opinion: Various strategies have been applied in preclinical and clinical settings to overcome cancer MDR. Among them are the use of chemosensitizers that aim to sensitize the cancer cells to chemotherapeutic treatment and the use of nanomedicines as delivery vehicles that can increase the influx of drugs into cancer cells. These strategies can enhance the therapeutic response in resistant tumors by bypassing efflux pumps or by increasing the nominal amounts of therapeutic payloads into the cancer cells at a given time point.     

黄酮类化合物对肿瘤多药耐药调节作用的研究进展

多药耐药是临床上化疗失败的重要原因之一。黄酮类化合物存在于多种植物中,具有广泛的药理活性,对P-糖蛋白(P-gp)、多药耐药相关蛋白(MRP)、乳腺癌耐药蛋白(BCRP)等外向转运蛋白的抑制作用使其可能成为肿瘤多药耐药调节剂。文中分别对黄酮类化合物对ABC家族转运蛋白抑制作用的研究概况、作用机制以及构效关系进行综述,为肿瘤多药耐药抑制剂的开发和应用提供重要信息。     

Effects of chemopreventive citrus phytochemicals on human P-glycoprotein and multidrug resistance protein 1

The effects of dietary chemopreventive citrus phytochemicals on the drug efflux transporters P-glycoprotein (ABCB1) and multidrug resistance protein 1 (MRP1, ABCC1) were investigated using P-glycoprotein-overexpressing human carcinoma KB-C2 cells and human MRP1 gene-transfected KB/MRP cells. The effects of natural chemopreventive citrus phytochemicals, such as auraptene, nobiletin, citral, citronellal, limonene, limonin, and synephrine were examined. The accumulation of daunorubicin, a fluorescent substrate of P-glycoprotein, increased in the presence of auraptene and nobiletin in KB-C2 cells. Nobiletin also increased the accumulation of calcein, a fluorescent substrate of MRP1, in KB/MRP cells. The ATPase activity of P-glycoprotein was stimulated by auraptene and nobiletin. The ATPase activity of MRP1 was stimulated by nobiletin. These results suggest that chemopreventive citrus phytochemicals, such as nobiletin found in oranges, have inhibitory effects on P-glycoprotein and/or MRP1, and may cause food–drug interactions.     

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。     

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。     

Marine sponge-derived sipholane triterpenoids reverse P-glycoprotein (ABCB1)-mediated multidrug resistance in cancer cells

Previously, we reported sipholenol A, a sipholane triterpenoid from the Red Sea sponge Callyspongia siphonella, as a potent reversal of multidrug resistance (MDR) in cancer cells that overexpressed P-glycoprotein (P-gp). Through extensive screening of several related sipholane triterpenoids that have been isolated from the same sponge, we identified sipholenone E, sipholenol L and siphonellinol D as potent reversals of MDR in cancer cells. These compounds enhanced the cytotoxicity of several P-gp substrate anticancer drugs, including colchicine, vinblastine and paclitaxel, and significantly reversed the MDR-phenotype in P-gp-overexpressing MDR cancer cells KB-C2 in a dose-dependent manner. Moreover, these three sipholanes had no effect on the response to cytotoxic agents in cells lacking P-gp expression or expressing MRP1 (ABCC1) or MRP7 (ABCC10) or breast cancer resistance protein (BCRP/ABCG2). All three sipholanes (IC₅₀ >50 μM) were not toxic to all the cell lines that were used. [³H]-Paclitaxel accumulation and efflux studies demonstrated that all three triterpenoids time-dependently increased the intracellular accumulation of [³H]-paclitaxel by directly inhibiting P-gp-mediated drug efflux. Sipholanes also inhibited calcein-AM transport from P-gp-overexpressing cells. The Western blot analysis revealed that these three triterpenoids did not alter the expression of P-gp. However, they stimulated P-gp ATPase activity in a concentration-dependent manner and inhibited the photolabeling of this transporter with its transport substrate [¹²⁵I]-iodoarylazidoprazosin. In silico molecular docking aided the virtual identification of ligand binding sites of these compounds. In conclusion, sipholane triterpenoids efficiently inhibit the function of P-gp through direct interactions and may represent potential reversal agents for the treatment of MDR.     

Enhancement of cellular uptake and cytotoxicity of curcumin-loaded PLGA nanoparticles by conjugation with anti-P-glycoprotein in drug resistance cancer cells

Aim:

To compare the anti-cancer activity and cellular uptake of curcumin (Cur) delivered by targeted and non-targeted drug delivery systems in multidrug-resistant cervical cancer cells.

Methods:

Cur was entrapped into poly (DL-lactide-co-glycolide) (PLGA) nanoparticles (Cur-NPs) in the presence of modified-pluronic F127 stabilizer using nano-precipitation technique. On the surface of Cur-NPs, the carboxy-terminal of modified pluronic F127 was conjugated to the amino-terminal of anti-P-glycoprotein (P-gp) (Cur-NPs-APgp). The physical properties of the Cur-NPs, including particle size, zeta potential, particle morphology and Cur release kinetics, were investigated. Cellular uptake and specificity of the Cur-NPs and Cur-NPs-APgp were detected in cervical cancer cell lines KB-V1 (higher expression of P-gp) and KB-3-1 (lower expression of P-gp) using fluorescence microscope and flow cytometry, respectively. Cytotoxicity of the Cur-NPs and Cur-NPs-APgp was determined using MTT assay.

Results:

The particle size of Cur-NPs and Cur-NPs-APgp was 127 and 132 nm, respectively. The entrapment efficiency and actual loading of Cur-NPs-APgp (60% and 5 μg Cur/mg NP) were lower than those of Cur-NPs (99% and 7 μg Cur/mg NP). The specific binding of Cur-NPs-APgp to KB-V1 cells was significantly higher than that to KB-3-1 cells. Cellular uptake of Cur-NPs-APgp into KB-V1 cells was higher, as compared to KB-3-1 cells. However, the cellular uptake of Cur-NPs and Cur-NPs-IgG did not differ between the two types of cells. Besides, the cytotoxicity of Cur-NPs-APgp in KB-V1 cells was higher than those of Cur and Cur-NPs.

Conclusion:

The results demonstrate that Cur-NPs-APgp targeted to P-gp on the cell surface membrane of KB-V1 cells, thus enhancing the cellular uptake and cytotoxicity of Cur.     

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。     

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。     

多药耐药基因MDR1多态性的研究进展

MDR1所编码的P-糖蛋白是ABC蛋白家族成员之一,它在体内药物的转运和处置中发挥着重要作用。本文就近几年有关MDR1基因多态性对P-糖蛋白在组织中表达的影响、以及MDR1多态性对药物处置、临床疗效以及疾病风险等影响进行综述。     

红霉素逆转人肝癌细胞BEL-7402多药耐药性的研究

目的　研究红霉素 (ERY)对BEL 740 2细胞 (人肝癌细胞 )多药耐药性的逆转作用。方法　将BEL 740 2细胞连续培养在含阿霉素 (ADM )的培养液中诱导耐药细胞株BEL 740 2 /ADM ,用cell ELASA法检测细胞膜表面P gp的表达 ,细胞毒试验采用MTT法 ,用荧光分光光度法测定细胞内ADM浓度。结果　BEL 740 2 /ADM细胞表面P gp高度表达 ,除对ADM耐药外 ,对长春新碱 (VCR)和丝裂霉素(MMC)也有不同程度的交叉耐药 ;ERY可增强ADM、VCR、MMC对BEL 740 2 /ADM细胞的增殖抑制作用 ,可增加BEL 740 2 /ADM细胞内ADM的浓度而对细胞膜表面P gp的表达没有影响。结论　ERY通过竞争性地饱和BEL 740 2 /ADM细胞表面P gp通道 ,使细胞内药物外排减少、浓度增加 ,从而发挥对BEL 740 2 /ADM细胞多药耐药性的逆转作用     

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。     

C421 allele-specific ABCG2 gene amplification confers resistance to the antitumor triazoloacridone C-1305 in human lung cancer cells

The A421 ABCG2 genotype is a frequent polymorphism encoding the K141 transporter, which is associated with a significant decrease in transporter expression and function when compared to the wild type (wt) C421 allele encoding the Q141 ABCG2. Here we show that during the acquisition of resistance to the novel triazoloacridone antitumor agent C-1305 in lung cancer cells harboring a heterozygous C421A genotype, a marked C421 allele-specific ABCG2 gene amplification occurred. This monoallelic C421 ABCG2 gene amplification brought about the overexpression of both C421 ABCG2 mRNA and the transporter at the plasma membrane. This resulted in the lack of cellular drug accumulation due to increased efflux of both C1305 and C-1311, a fluorescent imidazoacridone homologue of C-1305, as well as marked resistance to these antitumor agents and to established ABCG2 substrates including mitoxantrone and SN-38. Consistently, the accumulation and sensitivity to these drugs were restored upon incubation with the potent and specific ABCG2 transport inhibitors Ko143 and fumitremorgin C. Moreover, upon transfection into HEK293 cells, the wt Q141 ABCG2 allele displayed a significantly decreased accumulation of C-1311 and increased resistance to C-1305, C-1311 and mitoxantrone, when compared to the K141 ABCG2 transfectant. Hence, the current study provides the first evidence that during the exposure to anticancer drugs, an allele-specific Q141 ABCG2 gene amplification occurs that confers a drug resistance advantage when compared to the K141 ABCG2. These findings have important implications for the selection and expansion of malignant anticancer drug resistant clones during chemotherapy with ABCG2 drugs.     

The reversal of multidrug resistance in ovarian carcinoma cells by co-application of tariquidar and paclitaxel in transferrin-targeted polymeric micelles

In this study, a transferrin (Tf)-modified polyethylene glycol-phosphatidyl ethanolamine (PEG-PE)-based micellar delivery system containing paclitaxel (PTX) and tariquidar (TRQ), a potent third generation P-gp inhibitor, was prepared. The nanoformulation was evaluated by targeting efficiency, cellular association, cellular internalization pathway and cytotoxicity for reversal of PTX resistance on two multidrug resistant (MDR) ovarian carcinoma cell lines, SKOV-3TR and A2780-Adr. PTX and TRQ are both hydrophobic compounds. They were successfully encapsulated into the micellar structure containing vitamin E as the encapsulation enhancer. The Tf-targeted micelles were internalized mainly via clathrin-dependent endocytosis by both cell lines. For SKOV-3TR, additional mechanisms including caveolin-dependent endocytosis and macropinocytosis were found to play a significant role. The PTX cytotoxicity against the SKOV-3TR and A2780-Adr MDR cells was increased significantly in the presence of micellar encapsulation. However, unlike the A2780-Adr cell line, the Tf-targeting effect was significant on SKOV-3TR cells when co-administrated with TRQ. Penetration of the Tf-targeted micelles in a cancer cell spheroid culture was also investigated.     

新的四氢异喹啉类化合物CPUE1逆转K562/A02细胞的多药耐药性

目的 :研究新的四氢异喹啉类化合物CPUE1逆转K5 6 2 A0 2细胞多药耐药性的作用及机制。方法 :在CPUE1的作用下 ,用MTT法检测长春新碱(vincristine ,VCR)对K5 6 2 A0 2多药耐药细胞的细胞毒作用的变化 ,使用DNA分析和Annexin Ⅴ PI双染法研究CPUE1对VCR诱导K5 6 2 A0 2细胞凋亡的影响 ,流式细胞仪检测CPUE1对P 糖蛋白 (P glycop rotein ,P gp)外排罗丹明 12 3(rhodamine12 3,Rh12 3)的作用。结果 :CPUE1能明显提高VCR对K5 6 2 A0 2多药耐药细胞的细胞毒作用以及凋亡诱导作用 ,10 μmol·L-1的CPUE1能使K5 6 2 A0 2对VCR的IC50值由 6 0 .5 4μmol·L-1降至 4 .17μmol·L-1。CPUE1还能抑制Rh12 3外排从而增加细胞内Rh12 3的蓄积浓度。结论 :CPUE1通过抑制P gp的活性逆转K5 6 2 A0 2细胞的多药耐药性。     

洛美利嗪对人白血病细胞K562/ADM多药耐药的逆转作用

目的：研究洛美利嗪(lomerizine，Lom)对人白血病细胞K562／ADM多药耐药逆转作用及机制。方法：使用MTT法检测Lom对K562／ADM多药耐药细胞柔红霉素(DNR)细胞毒性的影响，使用荧光分光光度计和流式细胞术分析Lom对K562／ADM多药耐药细胞胞内P—糖蛋白(P—glycoprotein，P—gp)底物—罗丹明123(rhodamine 123，Rh123)的累积情况。结果：Lom能明显提高DNR对K562／ADM多药耐药细胞的细胞毒作用，并可使胞内Rh123的浓度增加。K562敏感细胞株则不受影响。结论：Lom能显地抑制：K562／ADM多药耐药细胞上P—gp的活性，提高P—gp底物的胞内浓度，并增强其他抗癌药的细胞毒作用。     

Overcoming drug resistance in pancreatic cancer

Introduction: Pancreatic cancer has the worst survival rate of all cancers. The current standard care for metastatic pancreatic cancer is gemcitabine, however, the success of this treatment is poor and overall survival has not improved for decades. Drug resistance (both intrinsic and acquired) is thought to be a major reason for the limited benefit of most pancreatic cancer therapies.

Areas covered: Previous studies have indicated various mechanisms of drug resistance in pancreatic cancer, including changes in individual genes or signaling pathways, the influence of the tumor microenvironment, and the presence of highly resistant stem cells. This review summarizes recent advances in the mechanisms of drug resistance in pancreatic cancer and potential strategies to overcome this.

Expert opinion: Increasing drug delivery efficiency and decreasing drug resistance is the current aim in pancreatic cancer treatment, and will also benefit the treatment of other cancers. Understanding the molecular and cellular basis of drug resistance in pancreatic cancer will lead to the development of novel therapeutic strategies with the potential to sensitize pancreatic cancer to chemotherapy, and to increase the efficacy of current treatments in a wide variety of human cancers.