Overcoming drug efflux-based multidrug resistance in cancer with nanotechnology

Multidrug resistance(MDR),which significantly decreases the efficacy of anticancer drugs and causes tumor recurrence,has been a major challenge in clinical cancer treatment with chemotherapeutic drugs for decades.Several mechanisms of overcoming drug resistance have been postulated.Well known P-glycoprotein(P-gp) and other drug efflux transporters are considered to be critical in pumping anticancer drugs out of cells and causing chemotherapy failure.Innovative theranostic(therapeutic and diagnostic) strategies with nanoparticles are rapidly evolving and are anticipated to offer opportunities to overcome these limits.In this review,we discuss the mechanisms of drug efflux-mediated resistance and the application of multiple nanoparticle-based platforms to overcome chemoresistance and improve therapeutic outcome.     

Immunotoxin resistance in multidrug resistant cells

Multidrug resistance (MDR) can be mediated, in part, by overexpression of P-glycoprotein (P-gp) and is characterized by broad resistance to several structurally, chemically, and pharmacologically distinct chemotherapeutic compounds. It has been hypothesized that immunological approaches to cytolysis may be used to overcome drug resistance. RV+ is a P-gp-expressing variant of the human myeloid leukemic cell line HL60 that displays a typical MDR phenotype. MDR RV+ cells displayed relative resistance to the immunotoxin (IT) HuM195-gelonin and to free rGelonin. K562 leukemia cells retrovirally infected to overexpress P-gp are also resistant to HuM195-gelonin. In addition, a monoclonal antibody capable of inhibiting the function of P-gp was able to partially reverse resistance to the IT. These data indicated that the expression of P-gp may contribute to IT resistance in RV+. Resistance to the IT was not mediated through decreased binding to cells, nor reduced internalization into the cell because the IT displayed similar kinetics of binding and internalization for both the parental HL60 and MDR RV+ cell lines. Comparison of the cytotoxicity of other ribosome-inactivating toxins indicated that RV+ cells were not universally resistant to toxins: RV+ cells were sensitive to the actions of ricin A chain, which acts on precisely the same RNase target as gelonin. Sensitivity of the MDR RV+ cells to the protein synthesis inhibitor cycloheximide, saponin, and Pseudomonas exotoxin A additionally confirmed that the resistance was not mediated through the ribosome and that pathways downstream from the inactivation of protein synthesis leading to cell death were not substantially perturbed in the MDR cells. Resistance could be partially abrogated by bafilomycin A, which inhibits lysosomal function. Moreover, direct visualization by confocal microscopy of the intracellular trafficking route of the IT showed that the IT accumulated preferentially in the lysosome in MDR RV+ cells but not in sensitive cells. These observations implicated the process of increased lysosomal degradation as the most likely basis for resistance. Such pathways of resistance may be important in the therapeutic applications of ITs, now becoming available for human use.     

Human multidrug resistant KB cells overexpress protein kinase C: involvement in drug resistance

Among the many phenotypic characteristics of multidrug resistance (MDR), the presence of P-glycoprotein is nearly always observed, and it appears that the plasma membrane of the multidrug resistant cell is integrally involved in controlling drug resistance. Another membrane-associated protein kinase, protein kinase C (PKC), has been shown to regulate the flow of information to the cell interior and to control the efflux of a number of different compounds. We therefore initiated a study of PKC and MDR. We found that multidrug resistant sublines from both mouse sarcoma 180 and human KB lines exhibited 80-90% increases in basal PKC activity. The mechanism of the increase appears to be quite different in the two cell lines. The human KB cells overexpress the alpha isozyme of PKC, commensurate with the increase in alpha-PKC protein, whereas the mouse cells do not overexpress alpha-mRNA but increase alpha-PKC protein. Furthermore, it appears that PKC activity plays a functional role in drug resistance, since inhibition of endogenous PKC activity by staurosporine resulted in decreased resistance to Adriamycin. We also found that phosphorylation of MDR cell membrane vesicles by purified PKC, followed by immunoprecipitation of P-glycoprotein with monoclonal antibody C219, resulted in a level of phosphorylation of P-glycoprotein that was greater than the endogenous phosphorylation level. The data presented indicate that MDR cells of diverse species exhibited enhanced PKC activity but that the mechanisms were different. The increased kinase activity may have biological relevance to MDR since PKC appears to be coupled to P-glycoprotein function.     

Modulation of drug sensitivity by dipyridamole in multidrug resistant tumor cells in vitro

The concept of overcoming multidrug resistance using modulators is based on the hypothesis that there will be a synergistic interaction between the modulator and the cytotoxic agent. We examined the ability of dipyridamole (DPM) to synergistically enhance drug sensitivity in drug-sensitive KB-3-1 cells and their drug-resistant variants, KB-GRC1 and KBV1 cells, using median effect analysis to produce a quantitative measure of the extent of synergy. The drug-resistant variants were resistant to vinblastine (VBL), colchicine (COL), and etoposide (VP-16) in the order VBL greater than COL greater than VP-16 on the basis of 50% inhibitory concentration values obtained by clonogenic assay with continuous drug exposure. The extent of staining with the monoclonal antibody HYB-241, directed at a Mr 180,000 form of the mdrI gene product, correlated with drug resistance for all three drugs (r greater than or equal to 0.92). DPM and verapamil elevated the steady state content (Css) of VBL, but there was no correlation between elevation of Css and the extent of synergy observed. DPM enhanced the cytotoxicity of VBL and COL in a synergistic manner in KB-GRC1 cells, and in KBV1 cells DPM interacted synergistically with VBL. VPL was synergistic with VBL only in KB-GRC1 cells. No synergy was observed in the parental KB-3-1 line. These data indicate that, although both DPM and verapamil can increase Css in cells not expressing P-glycoprotein, such an increase was not associated with synergy. In cells expressing mdrl, synergy was observed, and it was greatest for the cytotoxic agent for which expression of mdrl produced the greatest fold-resistance and enhancement of Css. However, neither the level of resistance, the level of expression of mdrl, nor the ability of the modulator to alter Css accurately predicted whether the interaction would be truly synergistic. We conclude that additional factors determine the nature of the drug interaction.     

EXPRESSION OF THE MULTIDRUG RESISTANCE GENE IN LEUKEMIC CELLS

P-glycoprotein(Pgp; Mr=170,000) to encoded by a family of genes-Multldrug resistance gene. The Pgp has been demonstrated to mediate resistance to multiple structurally dissimilar drugs, which fuctions as an energy- dependent efflux pump so that a cell with high level of mdr expression can more effectively eliminate cytotoxic drugs. In this report, a simplified method for analysis of clinical samples and assess the level of gene expression was set up. Furthermore, by using 32P labelled mdr- 1 cDNA as the probe and RNA dot blotting the mdr-mRNAs from 5 cases of myeloblastic leukemia cells were analysed. It was shown that the level of mdr-1 expression In different myeloleukeic cells was various and reduced In one case after remission. The established method for mRNA analysis could be generalized for evaluating the level of mRNA in clinical samples.     

Overcoming drug resistance in cancer cells with synthetic isoprenoids

A cultured subline (P388/ADM) of mouse P388 leukemia resistant to doxorubicin, vinblastine, vincristine, dactinomycin, and daunorubicin became sensitive again when treated with noncytotoxic doses of either of two synthetic isoprenoids: N-solanesyl-N,N'-bis(3,4-dimethoxybenzyl)ethylenediamine (SDB-ethylenediamine) and N-(p-methylbenzyl)decaprenylamine X HCI (PMB-decaprenylamine). The isoprenoids also reversed resistance to doxorubicin and vincristine in a cultured vincristine-resistant P388 leukemia subline (P388/VCR). Median lethal doses (LD50) for PMB-decaprenylamine and SDB-ethylenediamine administered ip were 123 and 350 mg/kg against mice, whereas the LD50 for verapamil, another modifier of cellular drug resistance, was about 7.6 mg/kg. In vivo experiments with P388/VCR-bearing mice showed that both SDB-ethylenediamine and verapamil overcame vincristine resistance, but PMB-decaprenylamine showed only slight activity. SDB-ethylenediamine was especially effective, overcoming the vincristine resistance at 1 mg drug/kg. Since the structure of SDB-ethylenediamine resembles that of verapamil, a calcium-blocking agent that overcomes drug resistance, it was checked for calcium-blocking activity. However, calcium channel-blocking activity was not observed with 20 micrograms isoprenoid/ml, whereas calcium channel activity was completely blocked by 1 microgram verapamil/ml.     

人肿瘤坏死因子-α基因转导绒癌耐药细胞系体外耐药逆转的研究

目的 将人肿瘤坏死因子-alpha(hTNF-α)基因导入已建立的绒癌耐药细胞系，观察hTNF-α基因转导后对绒癌细胞耐药性逆转的体外作用。方法 通过阳离子脂质体将hTNF-α基因转导绒癌耐药细胞系，用新霉素筛选含hTNF-α片段的单细胞克隆，用RT-PCR方法和细胞免疫组织化学方法，检测转导hTNF-α基因的耐药细胞中MDRl mRNA和MDRl蛋白(P-gp)表,达水平的改变。采用四甲基偶氮唑蓝比色法，检测转导hTNF-α基因的耐药细胞对足叶乙甙(VP-16)的耐药指数。结果 转导hTNF-α基因后，绒癌耐药细胞中检测出hTNF-α mRNA表达，转导hTNF-α基因在mRNA水平能一定程度的逆转绒癌耐药细胞的MDRl，而在P-gp蛋白水平几乎能完全逆转绒癌耐药细胞的MDRl。转导hTNF-α基因的细胞的耐药指数明显降低。结论 hTNF-α基因转导后，可通过调节MDRl的表达，来逆转绒癌耐药细胞系的耐药性。     

Combating apoptosis and multidrug resistant cancers by targeting lysosomes

Acquired therapy resistance is one of the prime obstacles for successful cancer treatment. Partial resistance is often acquired already during an early face of tumor development when genetic changes causing defects in classical caspase-dependent apoptosis pathway provide transformed cells with a growth advantage by protecting them against various apoptosis inducing stimuli including transforming oncogenes themselves and host immune system. Apoptosis defective cells are further selected during tumor progression and finally by apoptosis inducing treatments. Another form of resistance, multidrug resistance, arises during cancer treatment when cancer cells with effective efflux of cytotoxic agents escape the therapy. Remarkably, induction of lysosomal membrane permeabilization has recently emerged as an effective way to kill apoptosis resistant cancer cells and some lysosome targeting drugs can also re-sensitize multidrug resistant cells to classical chemotherapy. In this review, we highlight recent data on lysosomal cell death pathways and their implications for the future treatment of apoptosis defective and multidrug resistant aggressive tumors.     

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.     

人Glioblastoma/HHT多药耐药细胞系的建立及维拉帕米对耐药性的逆转作用

对人Ｇｌｉｏｂｌａｓｔｏｍａ细胞系采用反复短期暴露于高浓度的高三尖杉酯碱（ＨＨＴ）药液中的方法，建立了一株多药耐药（ＭＤＲ）细胞系，命名为Ｇｌｉｏｂｌａｓｔｏｍａ／ＨＨＴ。此细胞系高度表达Ｐ－糖蛋白（Ｐｇｐ），但无多药耐药相关蛋白（ＭＲＰ）的表达。５μｇ／ｍｌ维拉帕米（异搏定）能部分逆转Ｇｌｉｏｂｌａｓｔｏｍａ／ＨＨＴ细胞系的耐药性。２．５μｇ／ｍｌ～１０μｇ／ｍｌ异搏定不仅能增加Ｇｌｉｏｂｌａｓｔｏｍａ／ＨＨＴ细胞对柔红霉素（ＤＮＲ）的摄取量，也能减少ＤＮＲ的外排，而且上述作用随异搏定浓度的增加而增强     

具有转移能力鼻咽癌细胞株候选抗药与多药耐药相关基因的筛选

目的 筛选具有转移能力的鼻咽癌细胞株中候选抗药与多药耐药相关基因.方法 利用8000点的基因芯片比较5-8F和6-10B细胞株之间的差异表达基因,并利用在线MILANO程序分析,筛选抗药与多药耐药相关基因.半定量RT-PCR验证差异表达基因.结果 分析5-8F和6-10B细胞株之间基因表达谱后,共找到283个差异表达基因,其中表达上调基因185个,下调基因98个.MILANO程序分析后,在5-8F细胞株中找到4个可能与抗药和多药耐药相关的高表达基因:UGT1A9(15.85倍)、MVP(6.77倍)、CAV1(2.49倍)和HIF1A(2.67倍).半定量RT-PCR验证4个基因筛选结果的可靠性.结论 经在线MILANO程序分析鉴定的鼻咽癌5-8F和6-10B细胞株之间的差异表达基因可能与具有转移能力鼻咽癌细胞株的抗药和多药耐药有关.     

Evidence for reduced drug influx in multidrug resistant CEM cells by a fluorescent dye

Multidrug resistance (MDR) in cancer cells is commonly ascribed to a reduced drug accumulation mediated by an ATP dependent efflux pump. We have developed a new, rapid and quantitative method for measuring influx of BCECF-AM in sensitive (CEM) and MDR cells (CEM/VLB100). The fluorescence of intracellular accumulated BCECF after hydrolysis of BCECF-AM is rapidly visualized by spectrofluorometry. The rate of BCECF-AM entry into CEM/VLB100 cells is considerably lower than that found in CEM cells, similar to 10-fold after 10 min of incubation. This phenomenon is not in relation with a difference of esterase activities, it is not energy or intracellular pH-dependent, and BCECF efflux is negligible. CEM cells exhibited diffuse fluorescence within cytoplasm in contrast with numerous spots of intense labelling, related to the presence of the cytoplasmic vesicles in CEM/VLB100 cells demonstrated by Nomarski's microscopy. MDR modulators such as verapamil, sodium orthovanadate, chlorpromazine or trifluoperazine induce an enhanced influx in CEM/VLB100 cells (150+/-4%; 204+/-17%; 410+/-17% and 229+/-7% respectively) whereas no major differences were noted with the parental sensitive cells. Vinblastine (under conditions close to IC50) increases the influx only in MDR cells (481+/-6%) by a process that is not linked to competitive inhibition of the P170 efflux pump. These results suggest that reduced influx of drugs could be a major defect in MDR cells, a possible role for P170-membrane lipids interactions is discussed.     

携带PTEN基因重组腺病毒对群司珠单抗耐药乳腺癌细胞的逆转作用

摘 要 目的: 研究重组腺病毒介导的野生型PTEN基因转染对群司珠单抗(traxtuzumab)耐药性乳腺癌细胞的逆转作用。方法: 构建携带野生型PTEN基因的重组腺病毒AdPTEN，感染群司珠单抗耐药性乳腺癌细胞株BT474， MTT比色法和FCM检测AdPTEN感染对群司珠单抗作用下BT474细胞增殖和凋亡的影响； DNA片段化实验分析BT474凋亡与感染时间的关系； Western blotting法检测AdPTEN感染对BT474细胞中丝氨酸/苏氨酸激酶（Akt）磷酸化水平的影响。建立荷乳腺癌裸鼠模型，观察AdPTEN联合群司珠单抗治疗对乳腺癌移植瘤生长的影响，检测移植瘤细胞中PTEN蛋白的表达、细胞凋亡、超微结构的改变。结果: 成功构建重组腺病毒AdPTEN，其滴度为4.2×10 11T CID50/ml。PCR、RT-PCR和Western blotting法证实PTEN基因可被转导入BT474细胞内并稳定高效表达。AdPTEN联合群司珠单抗处理对BT474细胞增殖的抑制非常显著地强于单用群司珠单抗治疗（P<0.01）；细胞出现明显凋亡，凋亡率为（20.7±5.83）%，并且出现G1期阻滞和S期明显减少,与AdLacZ组和对照组相比差异均有统计学意义(P<0.01）；感染组细胞DNA出现典型的梯形条带, 以感染后24~36 h最为明显； AdPTEN感染明显下调BT474细胞内Akt的磷酸化水平。AdPTEN和群司珠单抗联合治疗可强烈抑制裸鼠移植瘤生长，疗效明显强于群司珠单抗治疗组(P<0.01）；AdPTEN治疗后，移植瘤细胞中PTEN表达明显，TUNEL和电镜检测均证实乳腺癌移植瘤细胞的凋亡。结论: AdPTEN治疗可抑制BT474细胞Akt 的磷酸化，阻断PI3K/Akt信号通路的持续活化，恢复耐药细胞对群司珠单抗的敏感性，引起细胞凋亡。     

多药耐药基因产物表达和细胞凋亡对胃癌影响的研究

目的　探讨多药耐药 (MDR)基因产物和细胞凋亡指数 (AI)表达与胃癌分型、分期、预后的关系。方法　应用免疫组化及原位末端标记法 (TUNEL) ,对 80例胃癌标本进行MDR指标 (P gp、GST π、TOPOⅡ )及AI检测。结果　P gp表达与临床分期有关 (P <0 .0 5 ) ,正常组织P gp表达高者生存期长 (P <0 .0 5 ) ;GST π表达强度与预后有关 ,高表达者生存期短 (P <0 .0 5 ) ;TOPOⅡ表达与分型有关 (P <0 .0 5 ) ,低分化癌表达高于高中分化癌 ;凋亡指数表达与临床分期有关 (P <0 .0 5 ) ,高表达者其临床分期越晚。结论　MDR与细胞凋亡都属细胞正常基因组表达的一部分 ,在正常组织及癌组织均可有表达。正常组织P gp、GST π的表达与预后有关 ,不同生存期的MDR与细胞凋亡表达差异无显著性 (P >0 .0 5 ) ,但MDR与AI的表达与胃癌的生物学行为有关     

Luteolin induces apoptosis in multidrug resistant cancer cells without affecting the drug transporter function: involvement of cell line-specific apoptotic mechanisms

Bioflavonoids are of considerable interest to human health as these serve as antioxidant and anticancer agents. Although epidemiological and experimental studies suggest that luteolin, a natural bioflavonoid, exhibits chemopreventive properties, its effectiveness as an antiproliferative agent against multidrug resistant (MDR) cancers is unclear. Thus, we assessed the antiproliferative effects of luteolin and associated molecular mechanisms using two MDR cancer cell lines that express high levels of P-glycoprotein and ABCG2. In this article, we demonstrate that luteolin induces apoptosis in P-glycoprotein- and ABCG2-expressing MDR cancer cells without affecting the transport functions of these drug transporters. Analysis of various proliferative signaling pathways indicated that luteolin-induced apoptosis involves reactive oxygen species generation, DNA damage, activation of ATR → Chk2 → p53 signaling pathway, inhibition of NF-kB signaling pathway, activation of p38 pathway and depletion of antiapoptotic proteins. Importantly, use of luteolin in these analyses also identified specific molecular characteristics of NCI-ADR/RES and MCF-7/Mito(R) cells that highlight their different tissue origins. These results suggest that luteolin possesses therapeutic potential to control the proliferation of MDR cancers without affecting the physiological function of drug transporters in the body tissues.     

Genistein modulates the decreased drug accumulation in non-P-glycoprotein mediated multidrug resistant tumour cells.

In tumour cells the pharmacological basis for multidrug resistance (MDR) often appears to be a reduced cellular cytostatic drug accumulation caused by the drug efflux protein, P-glycoprotein (Pgp MDR), or by other drug transporters (non-Pgp MDR). Here we report the reversal of the decreased daunorubicin (DNR) accumulation in five non-Pgp MDR cell lines (GLC4/ADR, SW-1573/2R120, HT1080/DR4, MCF7/Mitox and HL60/ADR) by genistein. Genistein inhibited the enhanced DNR efflux in the GLC4/ADR cells. In these cells the decreased VP-16 accumulation was also reversed by genistein. Three other (iso)flavonoids biochanin A, apigenin and quercetin also increased the DNR accumulation in the GLC4/ADR cells. In contrast to the effects on non-Pgp MDR cells, 200 microM genistein did not increase the reduced DNR accumulation in three Pgp MDR cell lines (SW-1573/2R160, MCF7/DOX40 and KB8-5) or in the parental cell lines. In conclusion the use of genistein provides a means to probe non-Pgp related drug accumulation defects.     

VX-710 (biricodar) increases drug retention and enhances chemosensitivity in resistant cells overexpressing P-glycoprotein, multidrug resistance protein, and breast cancer resistance protein.

PURPOSE: The pipecolinate derivative VX-710 (biricodar; Incel) is a clinically applicable modulator of P-glycoprotein (Pgp) and multidrug resistance protein (MRP-1); we studied its activity against the third multidrug resistance (MDR)-associated drug efflux protein, breast cancer resistance protein (BCRP). EXPERIMENTAL DESIGN: VX-710 modulation of uptake, retention, and cytotoxicity of mitoxantrone, daunorubicin, doxorubicin, topotecan, and SN38 was studied in cell lines overexpressing Pgp, MRP-1 and wild-type (BCRP(R482)) and mutant (BCRP(R482T)) BCRP. RESULTS: In 8226/Dox6 cells (Pgp), VX-710 increased mitoxantrone and daunorubicin uptake by 55 and 100%, respectively, increased their retention by 100 and 60%, respectively, and increased their cytotoxicity 3.1- and 6.9-fold, respectively. In HL60/Adr cells (MRP-1), VX-710 increased mitoxantrone and daunorubicin uptake by 43 and 130%, increased their retention by 90 and 60%, and increased their cytotoxicity 2.4- and 3.3-fold. In 8226/MR20 cells (BCRP(R482)), VX-710 increased mitoxantrone uptake and retention by 60 and 40%, respectively, and increased cytotoxicity 2.4-fold. VX-710 increased daunorubicin uptake and retention by only 10% in 8226/MR20 cells, consistent with the fact that daunorubicin is not a substrate for BCRP(R482), but, nevertheless, it increased daunorubicin cytotoxicity 3.6-fold, and this increase was not associated with intracellular drug redistribution. VX-710 had little effect on uptake, retention, or cytotoxicity of mitoxantrone, daunorubicin, doxorubicin, topotecan, or SN38 in MCF7 AdVP3000 cells (BCRP(R482T)). CONCLUSIONS: VX-710 modulates Pgp, MRP-1, and BCRP(R482), and has potential as a clinical broad-spectrum MDR modulator in malignancies such as the acute leukemias in which these proteins are expressed.