Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P33527 (ABCC1)
 1,164 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The active transport of oxidized glutathione and glutathione S-conjugates has been demonstrated for the first time in erythrocytes and this cell remained the main subject of research on the "glutathione S-conjugate pump" for years. Further studies identifled the "glutathione S-conjugate pump" as multidrug resistance-associated protein (MRP). Even though cells overexpressing MRP and isolated MRP provide useful information on MRP structure and function, the erythrocyte remains an interesting model cell for studies of MRP1 in its natural environment, including the substrate specificity and ATPase activity of the protein.
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PMID:Transport of organic anions by multidrug resistance-associated protein in the erythrocyte. 1131 Sep 75

Cisplatin (DDP) is one of the key drugs used to treat patients with ovarian cancer, although resistance to DDP can occur. Paclitaxel and SN-38 (an active metabolite of irinotecan (CPT-11)) are two drugs that are effective in patients with DDP-resistant ovarian cancer. To study how these drugs may overcome the intrinsic and / or acquired resistance of cancer cells to DDP, we investigated the effect of a combination of DDP with paclitaxel and a combination of DDP with SN-38 on three ovarian cancer cell lines, RTSG (intrinsically resistant cell line), KF (DDP-sensitive cell line), and KFra (acquired resistant cell line obtained from KF). We found that these combinations showed additive to synergistic antitumor activity. A time-dependent platinum (Pt) accumulation was observed in the DDP-sensitive KF cell line, while a decrease occurred in the KFra cell line. Little accumulation was observed in RTSG. Intracellular Pt accumulation was increased in all three cell lines by exposure to paclitaxel or SN-38. Ouabain, a Na(+),K(+)-ATPase inhibitor, decreased Pt accumulation in KF and KFra cell lines and inhibited the paclitaxel- and SN-38-induced increases in Pt accumulation in these cell lines. When we assessed the mRNA levels of the multidrug resistance-associated protein (MRP), which may be an efflux pump for DDP, the combination of paclitaxel or SN-38 with DDP down-regulated these levels, which are up-regulated by DDP alone. These results suggest that paclitaxel and SN-38 overcome DDP resistance of ovarian cell lines by controlling intracellular accumulation of DDP via both the influx and efflux systems.
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PMID:Paclitaxel and SN-38 overcome cisplatin resistance of ovarian cancer cell lines by down-regulating the influx and efflux system of cisplatin. 1171 50

Multidrug-resistance-associated protein 1 (MRP1/ABCC1) is a human ATP-binding cassette transporter that confers cell resistance to antitumour drugs. Its NBDs (nucleotide-binding domains) bind/hydrolyse ATP, a key step in the activation of MRP1 function. To relate its intrinsic functional features to the mechanism of action of the full-size transporter, we expressed the N-terminal NBD1 domain (Asn(642) to Ser(871)) in Escherichia coli. NBD1 was highly purified under native conditions and was characterized as a soluble monomer. (15)N-labelling allowed recording of the first two-dimensional NMR spectra of this domain. The NMR study showed that NBD1 was folded, and that Trp(653) was a key residue in the NBD1-ATP interaction. Thus, interaction of NBD1 with ATP/ADP was studied by intrinsic tryptophan fluorescence. The affinity for ATP and ADP were in the same range (K (d(ATP))=118 microM and K (d(ADP))=139 microM). Binding of nucleotides did not influence the monomeric state of NBD1. The ATPase activity of NBD1 was magnesium-dependent and very low [V (max) and K (m) values of 5x10(-5) pmol of ATP x (pmol NBD1)(-1) x s(-1) and 833 microM ATP respectively]. The present study suggests that NBD1 has a low contribution to the ATPase activity of full-length MRP1 and/or that this activity requires NBD1-NBD2 heterodimer formation.
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PMID:Biochemical characterization and NMR studies of the nucleotide-binding domain 1 of multidrug-resistance-associated protein 1: evidence for interaction between ATP and Trp653. 1295 82

The human ABC (ATP-binding cassette) transporter MRP1 (human multidrug-resistance-associated protein 1; ABCC1) is involved in the cellular extrusion of conjugated metabolites and causes multidrug resistance in tumour cells. The transport of substrate molecules by ABC proteins is energized by ATP hydrolysis, performed by two co-operating ABC units. Orthovanadate (Vi), a non-covalent inhibitor of the ABC ATPases, was found to catalyse a photo-oxidative cleavage of various ATP-binding proteins. In the present study, we have identified three Vi-cleavage sites within MRP1, and found that the cleavage reactions were variably modulated by the presence of nucleotides and by transported substrates. We concluded that Vi cleavage of MRP1 at Site I detects conformational changes due to the binding of MgATP. In contrast, Site II could be identified as part of the substrate-modulated catalytic cycle, probably containing an MRP1.MgADP.Vi transition-state-like complex. Cleavage at Site III was modulated by both the binding and hydrolysis of MgATP, in a biphasic pattern, which was also affected by the presence of transported substrates. We detected two different allosteric effects and found that they control two consecutive steps of the MRP1 ATPase catalytic cycle. Nucleotide binding to the low-affinity site accelerated the formation of the pre-hydrolytic intermediate in the other catalytic centre. Interaction of the transporter with its transported substrates stimulated a later reaction of the hydrolytic cycle, the formation of the post-hydrolytic intermediate, which could be detected in both catalytic sites by the experimental strategy used.
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PMID:Nucleotides and transported substrates modulate different steps of the ATPase catalytic cycle of MRP1 multidrug transporter. 1475 24

Tyrosine kinase inhibitors (TKIs) are promising new agents for specific inhibition of malignant cell growth and metastasis formation. Because most of the TKIs have to reach an intracellular target, specific membrane transporters may significantly modulate their effectiveness. In addition, the hydrophobic TKIs may interact with so-called multidrug transporters and thus alter the cellular distribution of unrelated pharmacological agents. In the present work, we show that certain TKIs, already in the clinical phase of drug development, directly interact with the ABCG2 multidrug transporter protein with a high affinity. We found that in several in vitro assay systems, STI-571 (Gleevec; imatinib mesylate), ZD1839 (Iressa; gefitinib), and N-[4-[(3-bromophenyl)amino]-6-quinazolinyl]-2-butynamide (EKI-785) interacted with ABCG2 at submicromolar concentrations, whereas other multidrug transporters, human multidrug resistance protein (P-glycoprotein, ABCB1) and human multidrug resistance protein 1 (ABCC1), showed much lower reactivity toward these agents. Low concentrations of the TKIs examined selectively modulated ABCG2-ATPase activity, inhibited ABCG2-dependent active drug extrusion, and significantly affected drug resistance patterns in cells expressing ABCG2. Our results indicate that multidrug resistance protein modulation by TKIs may be an important factor in the clinical treatment of cancer patients. These data also raise the possibility that an extrusion of TKIs by multidrug transporters, e.g., ABCG2, may be involved in tumor cell TKI resistance.
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PMID:High-affinity interaction of tyrosine kinase inhibitors with the ABCG2 multidrug transporter. 1515 41

The blood-cerebrospinal fluid barrier (BCSFB) plays a key role in the influx and efflux transport of drugs and endogenous substrates in the cerebrospinal fluid (CSF). To clarify the molecular mechanism of the BCSFB transport system, a new in vitro BCSFB model, i.e. an immortalized rat choroid plexus epithelial cell line (TR-CSFB), has been established from transgenic rats harboring a temperature-sensitive simian virus 40 large T-antigen gene. TR-CSFB cells grow well at 33 degrees C because of activation of the temperature-sensitive large T-antigen. These cells have a polygonal epithelial cell morphology and express typical choroid plexus epithelial cell markers, such as transthyretin (TTR) and Na+, K+ -ATPase, as well as the transporters, system A and ABCC1/mrp1. The localization of Na+, K+ -ATPase, and the transport direction of system A are polarized in TR-CSFB cells as is the case in vivo. TR-CSFB cells exhibit L-proline and L-glutamic acid uptake activities and may reflect the CSF-to-blood efflux transport functions involving these amino acids in vivo. Using TR-CSFB cells, we found for the first time that oatp3 is expressed at the BCSFB. TR-CSFB cells appear to be a useful in vitro model of the BCSFB for the study of drug transport, BCSFB transporters, and the regulation of BCSFB functions.
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PMID:A new in vitro model for blood-cerebrospinal fluid barrier transport studies: an immortalized choroid plexus epithelial cell line derived from the tsA58 SV40 large T-antigen gene transgenic rat. 1538 38

Overexpression of ABCB1 (MDR1) P-glycoprotein, a multidrug efflux pump, is one mechanism by which tumor cells may develop multidrug resistance (MDR), preventing the successful chemotherapeutic treatment of cancer. Sesquiterpenes from Celastraceae family are natural compounds shown previously to reverse MDR in several human cancer cell lines and Leishmania strains. However, their molecular mechanism of reversion has not been characterized. In the present work, we have studied the ability of 28 dihydro-beta-agarofuran sesquiterpenes to reverse the P-glycoprotein-dependent MDR phenotype and elucidated their molecular mechanism of action. Cytotoxicity assays using human MDR1-transfected NIH-3T3 cells allowed us to select the most potent sesquiterpenes reversing the in vitro resistance to daunomycin and vinblastine. Flow cytometry experiments showed that the above active compounds specifically inhibited drug transport activity of P-glycoprotein in a saturable, concentration-dependent manner (K(i) down to 0.24 +/- 0.01 micromol/L) but not that of ABCC1 (multidrug resistance protein 1; MRP1), ABCC2 (MRP2), and ABCG2 (breast cancer resistance protein; BCRP) transporters. Moreover, sesquiterpenes inhibited at submicromolar concentrations the P-glycoprotein-mediated transport of [(3)H]colchicine and tetramethylrosamine in plasma membrane from CH(R)B30 cells and P-glycoprotein-enriched proteoliposomes, supporting that P-glycoprotein is their molecular target. Photoaffinity labeling in plasma membrane and fluorescence spectroscopy experiments with purified protein suggested that sesquiterpenes interact with transmembrane domains of P-glycoprotein. Finally, sesquiterpenes modulated P-glycoprotein ATPase-activity in a biphasic, concentration-dependent manner: they stimulated at very low concentrations but inhibited ATPase activity as noncompetitive inhibitors at higher concentrations. Sesquiterpenes from Celastraceae are promising P-glycoprotein modulators with potential applications in cancer chemotherapy because of their MDR reversal potency and specificity for P-glycoprotein.
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PMID:Celastraceae sesquiterpenes as a new class of modulators that bind specifically to human P-glycoprotein and reverse cellular multidrug resistance. 1546 10

MRP1 (multidrug-resistance-associated protein 1; also known as ABCC1) is a member of the human ABC (ATP-binding cassette) transporter superfamily that confers cell resistance to chemotherapeutic agents. Considering the structural and functional similarities to the other ABC proteins, the interaction between its two NBDs (nucleotide-binding domains), NBD1 (N-terminal NBD) and NBD2 (C-terminal NBD), is proposed to be essential for the regulation of the ATP-binding/ATP-hydrolysis cycle of MRP1. We were interested in the ability of recombinant NBD1 and NBD2 to interact with each other and to influence ATPase activity. We purified NBD1 (Asn642-Ser871) and NBD2 (Ser1286-Val1531) as soluble monomers under native conditions. We measured extremely low intrinsic ATPase activity of NBD1 (10(-5) s(-1)) and NBD2 (6x10(-6) s(-1)) and no increase in the ATP-hydrolysis rate could be detected in an NBD1+NBD2 mixture, with concentrations up to 200 microM. Despite the fact that both monomers bind ATP, no stable NBD1.NBD2 heterodimer could be isolated by gel-filtration chromatography or native-PAGE, but we observed some significant modifications of the heteronuclear single-quantum correlation NMR spectrum of 15N-NBD1 in the presence of NBD2. This apparent NBD1.NBD2 interaction only occurred in the presence of Mg2+ and ATP. Partial sequential assignment of the NBD1 backbone resonances shows that residue Gly771 of the LSGGQ sequence is involved in NBD1.NBD2 complex formation. This is the first NMR observation of a direct interaction between the ABC signature and the opposite NBD. Our study also reveals that the NBD1.NBD2 heterodimer of MRP1 is a transient complex. This labile interaction is not sufficient to induce an ATPase co-operativity of the NBDs and suggests that other structures are required for the ATPase activation mechanism.
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PMID:Attempts to characterize the NBD heterodimer of MRP1: transient complex formation involves Gly771 of the ABC signature sequence but does not enhance the intrinsic ATPase activity. 1601 4

Multidrug resistance is a major cause of chemotherapy failure in cancer patients. One of the resistance mechanisms is the overexpression of drug efflux pumps such as P-glycoprotein and multidrug resistance protein 1 (MRP1, (ABCC1)). In this study, curcumin mixture and three major curcuminoids purified from turmeric (curcumin I, II, and III) were tested for their ability to modulate the function of MRP1 using HEK293 cells stably transfected with MRP1-pcDNA3.1 and pcDNA3.1 vector alone. The IC(50) of curcuminoids in these cell lines ranged from 14.5-39.3 microM. Upon treating the cells with etoposide in the presence of 10 microM curcuminoids, the sensitivity of etoposide was increased by several folds only in MRP1 expressing and not in pcDNA3.1-HEK 293 cells. Western blot analysis showed that the total cellular level of MRP1 protein level was not affected by treatment with 10 microM curcuminoids for three days. The modulatory effect of curcuminoids on MRP1 function was confirmed by the inhibition of efflux of two fluorescent substrates, calcein-AM and fluo4-AM. Although all the three curcuminoids increased the accumulation of fluorescent substrates in a concentration-dependent manner, curcumin I was the most effective inhibitor. In addition, curcuminoids did not affect 8-azido[alpha-(32)P]ATP binding, however they did stimulate the basal ATPase activity and inhibited the quercetin-stimulated ATP hydrolysis of MRP1 indicating that these bioflavonoids interact most likely at the substrate-binding site(s). In summary, these results demonstrate that curcuminoids effectively inhibit MRP1-mediated transport and among curcuminoids, curcumin I, a major constituent of curcumin mixture, is the best modulator.
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PMID:Curcuminoids purified from turmeric powder modulate the function of human multidrug resistance protein 1 (ABCC1). 1602 89

Many studies have been performed with the aim of developing effective resistance modulators to overcome the multidrug resistance (MDR) of human cancers. Potent MDR modulators are being investigated in clinical trials. Many current studies are focused on dietary herbs due to the fact that these have been used for centuries without producing any harmful side effects. In this study, the effect of tetrahydrocurcumin (THC) on three ABC drug transporter proteins, P-glycoprotein (P-gp or ABCB1), mitoxantrone resistance protein (MXR or ABCG2) and multidrug resistance protein 1 (MRP1 or ABCC1) was investigated, to assess whether an ultimate metabolite form of curcuminoids (THC) is able to modulate MDR in cancer cells. Two different types of cell lines were used for P-gp study, human cervical carcinoma KB-3-1 (wild type) and KB-V-1 and human breast cancer MCF-7 (wild type) and MCF-7 MDR, whereas, pcDNA3.1 and pcDNA3.1-MRP1 transfected HEK 293 and MXR overexpressing MCF7AdrVp3000 or MCF7FL1000 and its parental MCF-7 were used for MRP1 and MXR study, respectively. We report here for the first time that THC is able to inhibit the function of P-gp, MXR and MRP1. The results of flow cytometry assay indicated that THC is able to inhibit the function of P-gp and thereby significantly increase the accumulation of rhodamine and calcein AM in KB-V-1 cells. The result was confirmed by the effect of THC on [(3)H]-vinblastine accumulation and efflux in MCF-7 and MCF-7MDR. THC significantly increased the accumulation and inhibited the efflux of [(3)H]-vinblastine in MCF-7 MDR in a concentration-dependent manner. This effect was not found in wild type MCF-7 cell line. The interaction of THC with the P-gp molecule was clearly indicated by ATPase assay and photoaffinity labeling of P-gp with transport substrate. THC stimulated P-gp ATPase activity and inhibited the incorporation of [(125)I]-iodoarylazidoprazosin (IAAP) into P-gp in a concentration-dependent manner. The binding of [(125)I]-IAAP to MXR was also inhibited by THC suggesting that THC interacted with drug binding site of the transporter. THC dose dependently inhibited the efflux of mitoxantrone and pheophorbide A from MXR expressing cells (MCF7AdrVp3000 and MCF7FL1000). Similarly with MRP1, the efflux of a fluorescent substrate calcein AM was inhibited effectively by THC thereby the accumulation of calcein was increased in MRP1-HEK 293 and not its parental pcDNA3.1-HEK 293 cells. The MDR reversing properties of THC on P-gp, MRP1, and MXR were determined by MTT assay. THC significantly increased the sensitivity of vinblastine, mitoxantrone and etoposide in drug resistance KB-V-1, MCF7AdrVp3000 and MRP1-HEK 293 cells, respectively. This effect was not found in respective drug sensitive parental cell lines. Taken together, this study clearly showed that THC inhibits the efflux function of P-gp, MXR and MRP1 and it is able to extend the MDR reversing activity of curcuminoids in vivo.
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PMID:Modulation of function of three ABC drug transporters, P-glycoprotein (ABCB1), mitoxantrone resistance protein (ABCG2) and multidrug resistance protein 1 (ABCC1) by tetrahydrocurcumin, a major metabolite of curcumin. 1696 Jun 58


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