MRP1/MRP2与重金属转运的研究进展

多药耐药相关蛋白(multidrug resistance-associatedprotein,MRPs)是ATP结合盒式转运蛋白(ATP-binding cassette,ABC)家族中的一个亚群,1992年由Cole等[1]最初在耐阿霉素小细胞肺癌细胞株H69/AR的研究中发现,该耐药细胞株表达了一种不同于P糖蛋白(P-gp)的蛋白,此后命名为多药耐药相关蛋白1(multidrug resistance-associated protein 1,MRP1/ABCC1)。随后人们又陆续发现多药耐药相关蛋白2(multidrugresistance-associated protein 2,MRP2/ABCC2)及MRPs的其他成员。MRP1和MRP2是细胞代谢产物、药物、     

以膜转运蛋白为靶点的胃癌多药耐药研究进展

胃癌是我国病死率最高的常见恶性肿瘤,肿瘤多药耐药（MDR）严重影响临床化疗的效果,而膜转运蛋白如P－糖蛋白（P－gp）、MDR相关蛋白（MRP）、乳腺癌耐药蛋白(BCRP)和肺耐药相关蛋白(LRP)的异常表达是引起肿瘤多药耐药的重要机制之一. 简述上述4种膜转运蛋白在胃癌中的异常表达、耐药机制、临床意义及其逆转药.     

ABCC家族基因变异性研究进展

ATP结合盒亚家族C（ATP—Binding Cassette，Subfamily C，ABCC）蛋白家族是新近发现的一个较大的蛋白家族。该家族目前由9个成员所组成，在人体内分布广泛，参与机体内一些重要物质的转运。同时许多化疗药物也是它们的转运底物，其过度表达往往与肿瘤的多药耐药密切相关。最新研究表明，ABCC基因变异可以导致机体内物质代谢的改变和肿瘤耐药程度的改变，有的甚至可以直接导致遗传性疾病的产生。本文对AB—CC家族变异现象及其与肿瘤多药耐药的关系作一综述。     

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。     

五味子醇甲逆转MRP1多药耐药机制的研究

肿瘤的多药抗药性（muhidrug resistance,MDR）是肿瘤化疗失败的主要原因之一。我们及他人的研究已证实五味子醇甲（Schisandrol A）可以逆转P—gP介导的耐药。本实验中,我们以MRP介导的白血病多药耐药细胞株HL-60／ADR和HL-60／MRP为研究对象,探讨了五味子醇甲逆转MRP耐药的作用机理,以进一步阐明耐药发生机制。     

泌尿系肿瘤多药耐药的研究进展

多药耐药(MDR)是导致临床化疗失败的重要原因，对MDR及其逆转药的研究成为克服肿瘤耐药和提高化疗疗效的关键所在。泌尿系常见肿瘤MDR的形成机制复杂，可能与P 糖蛋白(P gp)、多药耐药相关蛋白(MRP)等过度表达、凋亡基因的缺失或抗凋亡基因的过度表达等有关。逆转药有P gp抑制药、细胞因子等。     

阿霉素纳米粒对MRP介导的膀胱肿瘤多药耐药细胞株EJ/MRP多药耐药性的逆转作用

目的 研究阿霉素纳米粒对多药耐药相关蛋白(MRP)介导的膀胱肿瘤多药耐药的逆转作用.方法 采用四甲基偶氮唑盐(MTT)法测定药物的体外杀伤作用,应用流式细胞术测定细胞内药物浓度.结果 阿霉素纳米粒对EJ细胞的细胞毒作用与阿霉素相似,EJ/MRP 细胞对阿霉素纳米粒较阿霉素敏感4.00倍.结论 阿霉素纳米粒通过增加耐药细胞内阿霉素浓度而有效逆转多药耐药.     

贲门癌组织中多药耐药基因和多药耐药相关蛋白基因表达的临床研究

目的 了解多药耐药基因(MDR1)和多药耐药相关蛋白基因(MRP)在贲门癌组织中的表达及其临床意义。方法 采用逆转录-多聚酶链反应(RT-PCR)。观察46侧贲门癌及癌旁组织中MDR1和MRP的表达。结果 癌组织中MDR1和MRP表达的阳性率分别为63%和50%,均高于癌旁组织(P<0.05);贲门癌术前化疗者MDR1 mRNA和MRP mRNA表达水平显著高于未化疗者(P<0.05);中低分化肿瘤MDR1和MRP两基因mRNA表达水平高于高分化肿瘤(P<0.05)。结论 贲门癌组织中具有内源和获得性耐药性;MDR1和MRP表达与肿瘤的TNM分期无关,其高表达状态可预示肿瘤组织的分化不良。     

急性白血病的多药耐药及逆转

多药耐药或多药抗性（MDR）系指肿瘤细胞或白血病细胞对结构和作用靶位不同的多种化疗药物有交叉耐药性,为化疗失败主要原因之一。按MDR发生机制有以下几点:（1）细胞膜上能量外排泵介导的 MDR,以 mdr-1/Pgp、MRP为代表;（2）胞质酶介导的MDR,以GST为代表;（3）胞核核孔蛋白介导的MDR,     

外排型转运体介导的抗肿瘤药物多药耐药的研究进展

多药耐药（MDR）是指肿瘤细胞接触一种抗肿瘤药物后,也对其他多种结构不同、功能不同的抗肿瘤药物产生耐药性,其中外排型转运体所介导的MDR是其中至关重要的一部分。外排型转运体是指位于肿瘤细胞生物膜上的具有将抗肿瘤药物从细胞内外排到细胞外的转运体。已知的具有外排作用的转运体有P糖蛋白（P-gp）、多药耐药相关蛋白（MRP）、乳腺癌耐药蛋白（BCRP）和肺耐药蛋白（LRP）。综述这几种外排型转运体的一般性质并着重于阐述逆转这些转运体介导的多药耐药的药物及方法。     

Nanoparticle delivery of anticancer drugs overcomes multidrug resistance in breast cancer

Breast cancer is a serious threat to women's health, because multidrug resistance (MDR) has hampered treatment and prognosis. Nanodelivery of anticancer agents is a new technology to be exploited in the treatment of patients, because it bypasses multispecific drug efflux transporters such as P-glycoprotein (ABCB1), multidrug resistance protein-1 (MRP1, ABCC1) and breast cancer resistance protein (BCRP, ABCG2). Drugs can be delivered to tumor tissue by passive and active tumor targeting strategies, which may reduce or reverse drug resistance. This review will mainly focus on MDR-associated proteins, as well as various nanoparticle formulations developed to overcome MDR in breast cancer.     

Structural and functional properties of human multidrug resistance protein 1 (MRP1/ABCC1)

Multidrug ABC transporters such as P-glycoprotein (P-gp/MDR1/ABCB1) and multidrug resistance protein 1 (MRP1/ABCC1) play an important role in the extrusion of drugs from the cell and their overexpression can be a cause of failure of anticancer and antimicrobial chemotherapy. Recently, the mouse P-gp/Abcb1a structure has been determined and this has significantly enhanced our understanding of the structure-activity relationship (SAR) of mammalian ABC transporters. This paper highlights our current knowledge on the structural and functional properties and the SAR of human MRP1/ABCC1. Although the crystal structure of MRP1/ABCC1 has yet to be resolved, the current topological model of MRP1/ABCC1 contains two transmembrane domains (TMD1 and TMD2) each followed by a nucleotide binding domain (NBD) plus a third NH2-terminal TMD0. MRP1/ABCC1 is expressed in the liver, kidney, intestine, brain and other tissues. MRP1/ABCC1 transports a structurally diverse array of important endogenous substances (e.g. leukotrienes and estrogen conjugates) and xenobiotics and their metabolites, including various conjugates, anticancer drugs, heavy metals, organic anions and lipids. Cells that highly express MRP1/ABCC1 confer resistance to a variety of natural product anticancer drugs such as vinca alkaloids (e.g. vincristine), anthracyclines (e.g. etoposide) and epipodophyllotoxins (e.g. doxorubicin and mitoxantrone). MRP1/ABCC1 is associated with tumor resistance which is often caused by an increased efflux and decreased intracellular accumulation of natural product anticancer drugs and other anticancer agents. However, most compounds that efficiently reverse P-gp/ABCB1-mediated multidrug resistance have only low affinity for MRP1/ABCC1 and there are only a few effective and relatively specific MRP1/ABCC1 inhibitors available. A number of site-directed mutagenesis studies, biophysical and photolabeling studies, SAR and QSAR, molecular docking and homology modeling studies have documented the role of multiple residues in determining the substrate specificity and inhibitor selectivity of MRP1/ABCC1. Most of these residues are located in the TMs of TMD1 and TMD2, in particular TMs 4, 6, 7, 8, 10, 11, 14, 16, and 17, or in close proximity to the membrane/cytosol interface of MRP1/ABCC1. The exact transporting mechanism of MRP1/ABCC1 is unclear. MRP1/ABCC1 and other multidrug transporters are front-line mediators of drug resistance in cancers and represent important therapeutic targets in future chemotherapy. The crystal structure of human MRP1/ABCC1 is expected to be resolved in the near future and this will provide an insight into the SAR of MRP1/ABCC1 and allow for rational design of anticancer drugs and potent and selective MRP1/ABCC1 inhibitors.     

Multidrug resistance-associated proteins and implications in drug development

1.  The multidrug resistance-associated proteins (MRPs) belong to the ATP-binding cassette superfamily (ABCC family) of transporters that are expressed differentially in the liver, kidney, intestine and blood–brain barrier. There are nine human MRPs that transport a structurally diverse array of endo- and xenobiotics as well as their conjugates.
2.  Multidrug resistance-associated protein 1 can be distinguished from MRP2 and MRP3 by its higher affinity for leukotriene C₄. Unlike MRP1, MRP2 functions in the extrusion of endogenous organic anions, such as bilirubin glucuronide and certain anticancer agents. In addition to the transport of glutathione and glucuronate conjugates, MRP3 has the additional capability of mediating the transport of monoanionic bile acids.
3.  Both MRP4 and MRP5 are able to mediate the transport of cyclic nucleotides and confer resistance to certain antiviral and anticancer nucleotide analogues. Hereditary deficiency of MRP6 results in pseudoxanthoma elasticum. In the body, MRP6 is involved in the transport of glutathione conjugates and the cyclic pentapeptide BQ123.
4.  Various MRPs show considerable differences in tissue distribution, substrate specificity and proposed physiological function. These proteins play a role in drug disposition and excretion and thus are implicated in drug toxicity and drug interactions. Increased efflux of natural product anticancer drugs and other anticancer agents mediated by MRPs from cancer cells is associated with tumour resistance.
5.  A better understanding of the function and regulating mechanisms of MRPs could help minimize and avoid drug toxicity and unfavourable drug–drug interactions, as well as help overcome drug resistance.     

Kinetic validation of the use of carboxydichlorofluorescein as a drug surrogate for MRP5-mediated transport

Multidrug resistance protein-5 (MRP5, ABCC5) is a member of the ATP-binding cassette transporter superfamily that effluxes a broad range of natural and xenobiotic compounds such as cyclic GMP, antiviral compounds, and cancer chemotherapeutic agents including nucleoside-based drugs, antifolate agents and platinum compounds. In cellular assays, MRP5 transfectants are less fluorescent after incubation with 5-chloromethylfluorescein diacetate (CMFDA). The present study examines the uptake of a close fluorescent analog, carboxydichlorofluorescein (CDCF), and drug substrates into inside-out membrane vesicles prepared from MRP transfected cells. MRP5-mediated uptake of CDCF was ATP-dependent and GSH-independent and possessed a K_m of 12 μM and a V_max of 56 pmol/min/mg prot. Comparison of kinetic parameters with drug substrates such as methotrexate (MTX), pemetrexed (Alimta™), and the metabolite of 5-fluorouracil, 5-fluorodeoxyuridine monophosphate (5-FdUMP) (K_m values of 0.3–1.3 mM) indicated that MRP5 has a 25–100-fold higher affinity for CDCF than for these drugs and that they share a common transport binding site. In addition, the potency of MRP5 inhibitors such as probenecid, MK571, and the phosphodiesterase 5 inhibitors correlated well between the uptake of CDCF and MTX. A survey of CDCF uptake by other MRPs revealed that MRP2 (ABCC2) also demonstrated ATP-dependent uptake with a K_m of 19 μM and V_max of 95.5 pmol/min/mg prot, while MRP1 (ABCC1) and MRP4 (ABCC4) had little to no uptake. Taken together, these data indicate that CDCF is a useful fluorescent drug surrogate with which to measure ATP-dependent MRP5-mediated transport.     

Folate concentration dependent transport activity of the Multidrug Resistance Protein 1 (ABCC1)

The Multidrug Resistance Protein MRP1 (ABCC1) can confer resistance to a variety of therapeutic drugs. In addition, MRP1/ABCC1 mediates cellular export of natural folates, such as folic acid and l-leucovorin. In this study we determined whether cellular folate status affected the functional activity of MRP1/ABCC1 mediated efflux of an established substrate, the anthracycline daunorubicin (DNR). As a model system we used the human ovarian carcinoma cell line 2008wt, and its MRP1/ABCC1 transfected subline 2008/MRP1. Both types of these moderate- and high-MRP1/ABCC1 expressing cells displayed efflux of DNR when maintained in standard culture media (2.3microM folic acid). The initial total cellular DNR efflux rate in 2008/MRP1 cells was approximately 2-fold higher compared to 2008wt cells. This efflux consisted of MRP1/ABCC1 mediated transport, possibly non-MRP1 mediated transport, as well as passive diffusion. Benzbromarone, a specific MRP1 inhibitor, decreased the initial efflux rate in 2008/MRP1 cells (4-fold) and in 2008wt cells (2-fold). When 2008/MRP1 cells were challenged for 2 days in folate-free medium, total cellular DNR efflux was decreased to 43% of the initial efflux rate under folate-rich conditions. In 2008wt cells DNR efflux was decreased to 84% of the folate-rich conditions. Benzbromarone did not inhibit DNR efflux after the folate-free period in both cell lines. Repletion of folate by a 2-24hr exposure to 2.5microM l-leucovorin or folic acid resulted in a complete restoration of DNR efflux. In contrast, expression of MRP1/ABCC1 protein was not changed significantly during the folate-free period or the repletion-period, nor were cellular ATP or ADP pools. In conclusion, this study demonstrates that the cellular folate status can influence the transport activity of MRP1/ABCC1. These results have potentially important implications in the understanding of the (patho-)physiological roles of MRP1/ABCC1, and possibly other ABC transporter proteins in cellular folate homeostasis and drug resistance.     

Substrates and inhibitors of human multidrug resistance associated proteins and the implications in drug development

Human contains 49 ATP-binding cassette (ABC) transporter genes and the multidrug resistance associated proteins (MRP1/ABCC1, MRP2/ABCC2, MRP3/ABCC3, MRP4/ABCC4, MRP5/ABCC5, MRP6/ABCC6, MRP7/ABCC10, MRP8/ABCC11 and MRP9/ABCC12) belong to the ABCC family which contains 13 members. ABCC7 is cystic fibrosis transmembrane conductance regulator; ABCC8 and ABCC9 are the sulfonylurea receptors which constitute the ATP-sensing subunits of a complex potassium channel. MRP10/ABCC13 is clearly a pseudo-gene which encodes a truncated protein that is highly expressed in fetal human liver with the highest similarity to MRP2/ABCC2 but without transporting activity. These transporters are localized to the apical and/or basolateral membrane of the hepatocytes, enterocytes, renal proximal tubule cells and endothelial cells of the blood-brain barrier. MRP/ABCC members transport a structurally diverse array of important endogenous substances and xenobiotics and their metabolites (in particular conjugates) with different substrate specificity and transport kinetics. The human MRP/ABCC transporters except MRP9/ABCC12 are all able to transport organic anions, such as drugs conjugated to glutathione, sulphate or glucuronate. In addition, selected MRP/ABCC members may transport a variety of endogenous compounds, such as leukotriene C(4) (LTC(4) by MRP1/ABCC1), bilirubin glucuronides (MRP2/ABCC2, and MRP3/ABCC3), prostaglandins E1 and E2 (MRP4/ABCC4), cGMP (MRP4/ABCC4, MRP5/ABCC5, and MRP8/ABCC11), and several glucuronosyl-, or sulfatidyl steroids. In vitro, the MRP/ABCC transporters can collectively confer resistance to natural product anticancer drugs and their conjugated metabolites, platinum compounds, folate antimetabolites, nucleoside and nucleotide analogs, arsenical and antimonial oxyanions, peptide-based agents, and in concert with alterations in phase II conjugating or biosynthetic enzymes, classical alkylating agents, alkylating agents. Several MRP/ABCC members (MRPs 1-3) are associated with tumor resistance which is often caused by an increased efflux and decreased intracellular accumulation of natural product anticancer drugs and other anticancer agents. Drug targeting of these transporters to overcome MRP/ABCC-mediated multidrug resistance may play a role in cancer chemotherapy. Most MRP/ABCC transporters are subject to inhibition by a variety of compounds. Based on currently available preclinical and limited clinical data, it can be expected that modulation of MRP members may represent a useful approach in the management of anticancer and antimicrobial drug resistance and possibly of inflammatory diseases and other diseases. A better understanding of their substrates and inhibitors has important implications in development of drugs for treatment of cancer and inflammation.     

Reversal of multidrug resistance by the P-glycoprotein modulator, LY335979, from the bench to the clinic

Multidrug resistance may be conferred by P-glycoprotein (Pgp, ABCB1) or the multidrug resistance associated protein (MRP). These membrane proteins are members of the ATP binding cassette transporter superfamily and are responsible for the removal from the cell of several anticancer agents including doxorubicin. Modulators can inhibit these transporters. LY335979 is among the most potent modulators of Pgp with a Ki of 59 nM. LY335979 is selective for Pgp, and does not modulate MRP-mediated resistance by MRP1 (ABCC1) and MRP2 (ABCC2). LY335979 significantly enhanced the survival of mice implanted with Pgp-expressing murine leukemia (P388/ADR) when administered in combination with either daunorubicin, doxorubicin or etoposide. Coadministration of LY335979 with paclitaxel compared to paclitaxel alone significantly reduced the tumor mass of the Pgp-expressing UCLA-P3.003VLB lung carcinoma in a xenograph model and delayed the development of tumors in mice implanted with the parental drug-sensitive UCLA-P3 tumor. LY335979 was without significant effect on the pharmacokinetics of these anticancer agents. This may be due impart to its poor inhibition of four major cytochrome P450 isozymes important in metabolizing doxorubicin and other oncolytics. The selectivity and potency of this modulator allows the clinical evaluation of the role of Pgp in multidrug resistance. LY335979 is currently in clinical trials.     

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。     

High-throughput screening identifies Ceefourin 1 and Ceefourin 2 as highly selective inhibitors of multidrug resistance protein 4 (MRP4)

Multidrug resistance protein 4 (MRP4/ABCC4), a member of the ATP-binding cassette (ABC) transporter superfamily, is an organic anion transporter capable of effluxing a wide range of physiologically important signalling molecules and drugs. MRP4 has been proposed to contribute to numerous functions in both health and disease; however, in most cases these links remain to be unequivocally established. A major limitation to understanding the physiological and pharmacological roles of MRP4 has been the absence of specific small molecule inhibitors, with the majority of established inhibitors also targeting other ABC transporter family members, or inhibiting the production, function or degradation of important MRP4 substrates. We therefore set out to identify more selective and well tolerated inhibitors of MRP4 that might be used to study the many proposed functions of this transporter. Using high-throughput screening, we identified two chemically distinct small molecules, Ceefourin 1 and Ceefourin 2, that inhibit transport of a broad range of MRP4 substrates, yet are highly selective for MRP4 over other ABC transporters, including P-glycoprotein (P-gp), ABCG2 (Breast Cancer Resistance Protein; BCRP) and MRP1 (multidrug resistance protein 1; ABCC1). Both compounds are more potent MRP4 inhibitors in cellular assays than the most widely used inhibitor, MK-571, requiring lower concentrations to effect a comparable level of inhibition. Furthermore, Ceefourin 1 and Ceefourin 2 have low cellular toxicity, and high microsomal and acid stability. These newly identified inhibitors should be of great value for efforts to better understand the biological roles of MRP4, and may represent classes of compounds with therapeutic application.     

介导肿瘤多药耐药的ATP结合盒转运体的研究进展

多药耐药（MDR）是阻碍肿瘤化疗成功的一大障碍,其机制之一就是耐药的肿瘤细胞高表达三磷酸腺苷（ATP）结合盒（ABC）转运体。依据此机制提出克服肿瘤细胞耐药的策略即开发外排转运体抑制剂,以期逆转MDR。最近的研究发现肿瘤干细胞也可能是通过表达外排转运体天然耐药,这就提供了一个新的抗癌药物作用靶点。对介导肿瘤细胞多药耐药的ABC转运体及其抑制剂的开发作一综述。