Home About us Contact
|
Home About us Contact | ||
|
|
||
Multidrug Resistance Protein (multidrug + resistance_protein)
Selected AbstractsAnticancer multidrug resistance mediated by MRP1: Recent advances in the discovery of reversal agentsMEDICINAL RESEARCH REVIEWS, Issue 4 2005Ahcène Boumendjel Abstract Multidrug resistance protein 1 (MRP1) belongs to the ATP-binding cassette (ABC) transporter family. It is able to transport a broad range of anticancer drugs through cellular membranes, thus limiting their antiproliferative action. Since its discovery in 1992, MRP1 has been the most studied among MRP proteins, which now count nine members. Besides the biological work, which targets structure elucidation, binding sites location, and mode of action, most efforts have been focused on finding molecules which act as MRP1 inhibitors. In this review, we attempt to summarize and highlight studies dealing with modulators of MRP1-mediated multidrug resistance (MDR), which have been accomplished in the last 5 years. The reported MRP1 inhibitors are discussed according to their chemical class. Finally, we try to bring information on structure,activity relationship (SAR) aspects and how modulators might interact with MRP1. This study may facilitate the rational design of future modulators of MDR. © 2005 Wiley Periodicals, Inc. [source] HIV-1 viral envelope glycoprotein gp120 produces oxidative stress and regulates the functional expression of multidrug resistance protein-1 (Mrp1) in glial cellsJOURNAL OF NEUROCHEMISTRY, Issue 3 2008Patrick T. Ronaldson Abstract Brain human immunodeficiency virus type-1 (HIV-1) infection is associated with oxidative stress, which may lead to HIV-1 encephalitis, a chronic neurodegenerative condition. In vitro, oxidative stress can be induced in glial cells by exposure to HIV-1 envelope protein glycoprotein (gp120). Multidrug resistance proteins (Mrps) are known to efflux endogenous substrates (i.e. GSH and GSSG) involved in cellular defense against oxidative stress. Altered GSH/GSSG export may contribute to oxidative damage during HIV-1 encephalitis. At present, it is unknown if gp120 exposure can alter the functional expression of Mrp isoforms. Heat-shock protein 70, inducible nitric oxide synthase, intracellular GSSG, 2,,7,-dichlorofluorescein fluorescence, and extracellular nitrite were increased in primary cultures of rat astrocytes triggered with gp120, suggesting an oxidative stress response. RT-PCR and immunoblot analysis demonstrated increased Mrp1 mRNA (2.3-fold) and protein (2.2-fold), respectively, in gp120 treated astrocytes while Mrp4 mRNA or protein expression was not changed. Cellular retention of 2,,7,-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein, an established Mrp substrate, was reduced (twofold) in gp120-treated astrocytes, suggesting increased Mrp-mediated transport. In addition, GSH and GSSG export were enhanced in gp120-triggered cells. These data suggest that gp120 can up-regulate Mrp1, but not Mrp4, functional expression in cultured astrocytes. Our observation of increased GSH/GSSG efflux in response to gp120 treatment implies that Mrp isoforms may be involved in regulating the oxidative stress response in glial cells. [source] Structural requirements for the apical sorting of human multidrug resistance protein 2 (ABCC2)FEBS JOURNAL, Issue 7 2002Anne T. Nies The human multidrug resistance protein 2 (MRP2, symbol ABCC2) is a polytopic membrane glycoprotein of 1545 amino acids which exports anionic conjugates across the apical membrane of polarized cells. A chimeric protein composed of C-proximal MRP2 and N-proximal MRP1 localized to the apical membrane of polarized Madin,Darby canine kidney cells (MDCKII) indicating involvement of the carboxy-proximal part of human MRP2 in apical sorting. When compared to other MRP family members, MRP2 has a seven-amino-acid extension at its C-terminus with the last three amino acids (TKF) comprising a PDZ-interacting motif. In order to analyze whether this extension is required for apical sorting of MRP2, we generated MRP2 constructs mutated and stepwise truncated at their C-termini. These constructs were fused via their N-termini to green fluorescent protein (GFP) and were transiently transfected into polarized, liver-derived human HepG2 cells. Quantitative analysis showed that full-length GFP,MRP2 was localized to the apical membrane in 73% of transfected, polarized cells, whereas it remained on intracellular membranes in 27% of cells. Removal of the C-terminal TKF peptide and stepwise deletion of up to 11 amino acids did not change this predominant apical distribution. However, apical localization was largely impaired when GFP,MRP2 was C-terminally truncated by 15 or more amino acids. Thus, neither the PDZ-interacting TKF motif nor the full seven-amino-acid extension were necessary for apical sorting of MRP2. Instead, our data indicate that a deletion of at least 15 C-terminal amino acids impairs the localization of MRP2 to the apical membrane of polarized cells. [source] Nucleotide-binding domain 1 of cystic fibrosis transmembrane conductance regulatorFEBS JOURNAL, Issue 17 2000Production of a suitable protein for structural studies Cystic fibrosis is caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR). This protein belongs to the large ATP-binding cassette (ABC) family of transporters. Most patients with cystic fibrosis bear a mutation in the nucleotide-binding domain 1 (NBD1) of CFTR, which plays a key role in the activation of the channel function of CFTR. Determination of the three dimensional structure of NBD1 is essential to better understand its structure,function relationship, and relate it to the biological features of CFTR. In this paper, we report the first preparation of recombinant His-tagged NBD1, as a soluble, stable and isolated domain. The method avoids the use of renaturing processes or fusion constructs. ATPase activity assays show that the recombinant domain is functional. Using tryptophan intrinsic fluorescence, we point out that the local conformation, in the region of the most frequent mutation ,F508, could differ from that of the nucleotide-binding subunit of histidine permease, the only available ABC structure. We have undertaken three dimensional structure determination of NBD1, and the first two dimensional 15N- 1H NMR spectra demonstrate that the domain is folded. The method should be applicable to the structural studies of NBD2 or of other NBDs from different ABC proteins of major biological interest, such as multidrug resistance protein 1 or multidrug resistance associated protein 1. [source] Multidrug resistance,associated proteins are crucial for the viability of activated rat hepatic stellate cells,,HEPATOLOGY, Issue 2 2008Rebekka A. Hannivoort Hepatic stellate cells (HSCs) survive and proliferate in the chronically injured liver. ATP-binding cassette (ABC) transporters play a crucial role in cell viability by transporting toxic metabolites or xenobiotics out of the cell. ABC transporter expression in HSCs and its relevance to cell viability and/or activation have not been reported so far. The aim of this study was to investigate the expression, regulation, and function of multidrug resistance,associated protein (Mrp)-type and multidrug resistance protein (Mdr),type ABC transporters in activated rat HSCs. Rat HSCs were exposed to cytokines or oxidative stress. ABC transporter expression was determined by quantitative polymerase chain reaction and immunohistochemistry. HSCs were exposed to the Mdr inhibitors verapamil and PSC-833 and the Mrp inhibitor MK571. Mdr and Mrp transporter function was evaluated with flow cytometry. Apoptosis was determined by activated caspase-3 and acridine orange staining, and necrosis was determined by Sytox green nuclear staining. An in vivo model of carbon tetrachloride (CCl4),induced liver fibrosis was used. With respect to hepatocytes, activated HSCs expressed high levels of Mrp1 and comparable levels of Mrp3, Mrp4, Mdr1a, and Mdr1b but not the hepatocyte-specific transporters bile salt export pump, Mrp2, and Mrp6. Mrp1 protein staining correlated with desmin staining in livers from CCl4 -treated rats. Mrp1 expression increased upon activation of HSCs. Cytokines induced Mdr1b expression only. Oxidative stress was not a major regulator of Mdr and Mrp transporter expression. Activated HSCs became necrotic when exposed to the Mrp inhibitors. Conclusion: Activated HSCs contain relatively high levels of Mrp1. Mrp-type transporters are required for the viability of activated HSCs. Mrp-dependent export of endogenous metabolites is important for the survival of activated HSCs in chronic liver diseases. (HEPATOLOGY 2008.) [source] Matrine improves 17,-ethinyl estradiol-induced acute cholestasis in ratsHEPATOLOGY RESEARCH, Issue 11 2009Ying Zhao Aim:, To explore the effects of matrine (MT) on acute intrahepatic cholestasis induced by 17,-ethinyl estradiol (EE) in rats. Methods:, Acute intrahepatic cholestasis in rats were induced by EE, and the effects of MT on acute intrahepatic cholestasis were explored and compared with ursodeoxycholic acid (UDCA) by serum biochemical determination and bile excretion experiments. Results:, The serum biochemical and bile biochemical results indicated that MT and UDCA had notable hepatoprotective effects by counteracting cholestasis induced by EE. The bile flow and the bile excretion of glycocholic acid (GC, a substrate of bile salt export pump [Bsep]), ketoprofen glucuronide (KPG) and rhodamine 123 (Rh123, a substrate of multidrug resistance protein 1 [MDR1]) decreased by EE, were significantly improved after administration of MT. Conclusion:, MT exhibited potential protection against EE-induced acute intrahepatic cholestasis. [source] Effect of genipin on the biliary excretion of cholephilic compounds in ratsHEPATOLOGY RESEARCH, Issue 6 2008Masaki Mikami Aim:, Genipin, a metabolite of geniposide, is reported to stimulate the insertion of multidrug resistance protein 2 (Mrp2) in the bile canalicular membrane, and to cause choleresis by increasing the biliary excretion of glutathione, which has been considered to be a substrate of Mrp2. In the present study, the effect of colchicine on the choleretic effect of genipin was investigated. The effect of genipin on the biliary excretion of the substrates of bile salt export pump and Mrp2 was also studied. Methods:, After bile duct cannulation into rats, genipin was administered at the rate of 0.2 ,mol/min/100 g, and the effect of colchicine pretreatment (0.2 mg/100 g) was examined. Metabolites of genipin in the bile were examined by a thin layer chromatography. Taurocholate (TC), sulfobromophthalein (BSP), and pravastatin were infused at the rate of 1.0, 0.2 and 0.3 ,mol/min/100 g, respectively, and the effect of genipin co-administration was examined. Results:, Genipin increased bile flow and the biliary glutathione excretion, and those increases were not inhibited by colchicine. The biliary excretion of genipin glucuronide was less than 10% of the genipin excreted into bile. The biliary excretion of TC, BSP, and pravastatin was unchanged by genipin co-administration. Conclusion:, It was indicated that colchicine-sensitive vesicular transport has no role on the genipin-induced insertion of Mrp2 to the canalicular membrane. Choleresis of genipin is considered to be mainly due to the increased biliary glutathione excretion by genipin, not by the biliary excretion of glucuronide. TC had no effect on the biliary glutathione excretion. [source] The role of radixin in altered localization of canalicular conjugate export pump Mrp2 in cholestatic rat liverHEPATOLOGY RESEARCH, Issue 2 2008Hideyuki Kojima Aim:, Cholestasis has been associated with the endocytic retrieval of multidrug resistance protein 2 (Mrp2), but its mechanism is still unclear. Recent studies have indicated that radixin, a cross-linker between the actin filaments and membrane proteins, may be activated by phosphorylation and may be required for the canalicular localization of Mrp2. Methods:, We investigated the role of radixin in the altered localization of Mrp2 in rat models of intrahepatic (ethinyl estradiol treatment) and extrahepatic (bile duct ligation) cholestasis using immunofluorescence microscopy. The changes in localization and expression were analyzed using Scion Image for Windows. Results:, In both models, Mrp2 was localized outside as well as inside the ZO-1 staining, indicating partial dislocation from the canalicular membrane. In contrast to the steep elevation of the immunostaining intensity curves for Mrp2 in the controls, the corresponding curves in both models were broadened and flattened, confirming endocytic retrieval into the hepatocytes. Mrp2 and radixin were colocalized at the canalicular domain in the controls, whereas in both cholestatic rats they were dissociated at some canaliculi, indicating the disturbed colocalization of Mrp2 and radixin in cholestasis. The fluorescence of phosphorylated radixin, an active form of radixin, markedly decreased in both cholestatic models, which was supported by the reduced peak fluorescence intensities. Conclusion:, The disturbed colocalization of Mrp2 and radixin may contribute to the endocytic retrieval of Mrp2 in cholestasis due to the failure to anchor Mrp2 in the canalicular membrane, in which the phosphorylated radixin may play a major role. [source] Biliary excretion of azelnidipine, a calcium antagonist, in ratsJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 4 2004NAOKO HANAWA Abstract Background and Aims:, Azelnidipine (CS-905) is a novel dihydropyridine calcium antagonist that is known to be excreted in feces. To examine the mechanism of biliary excretion of azelnidipine, the authors studied its biliary excretion in Eisai hyperbilirubinuria rats (EHBR), multidrug resistance protein (Mrp)2-deficient rats, and the effect of cholephilic compounds on the biliary excretion of azelnidipine in rats. Methods:, Radiolabeled azelnidipine was intravenously administered to EHBR and control rats, and the biliary excretion of radiolabeled metabolites was studied. Furthermore, the effect of sulfobromophthalein, taurocholate and vinblastine on the biliary excretion of azelnidipine metabolites was also studied in control rats. Results:, The biliary excretion of azelnidipine metabolites was delayed in EHBR. The biliary excretion of azelnidipine metabolites was inhibited by sulfobromophthalein and vinblastine, but was not inhibited by taurocholate or phenothiazine pretreatment. Conclusion:, These findings suggest that the metabolites of azelnidipine are excreted into the bile partly by Mrp2 and P-glycoprotein. [source] Effluxing ABC transporters in human corneal epitheliumJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 2 2010Kati-Sisko Vellonen Abstract ATP-binding cassette (ABC) transporters are able to efflux their substrate drugs from the cells. We compared expression of efflux proteins in normal human corneal epithelial tissue, primary human corneal epithelial cells (HCEpiC), and corneal epithelial cell culture model (HCE model) based on human immortal cell line. Expression of multidrug resistance protein 1 (MDR1), multidrug resistance-associated protein 1,6 (MRP1,6) and breast cancer resistance protein (BCRP) was studied using quantitative RT-PCR, Western blot, and immunohistochemistry. Only MRP1, MRP5, and BCRP were expressed in the freshly excised human corneal epithelial tissue. Expression of MRP1 and MRP5 was localized predominantly in the basal cells of the central cornea and limbus. Functional efflux activity was shown in the cell models, but they showed over-expression of most efflux transporters compared to that of normal corneal epithelium. In conclusion, MRP1, MRP5, and BCRP are expressed in the corneal epithelium, but MDR1, MRP2, MRP3, MRP4, and MRP6 are not significantly expressed. HCE cell model and commercially available primary cells deviate from this expression profile. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:1087,1098, 2010 [source] The Influence of Acetylcholinesterase Reactivators on Selected Hepatic Functions in RatsBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 2 2008Jaroslav Pejchal Male Wistar rats were randomly divided to seven groups and intramuscularly administered with saline and acetylcholinesterase reactivators (K027, HI-6 and obidoxime) at doses of 5% LD50 and 50% LD50. Liver tissue samples were taken 24 hr after administration. Histochemical detection of lipid droplets and immunohistochemical detection of multidrug resistance protein 2 (Mrp2) were provided. Lipid droplet count in rat liver did not show any significant differences in animals administered with K027, HI-6 and obidoxime in comparison with the control group. Mrp2 protein expression significantly decreased when animals were administered with K027 at a dose of 50% LD50 and HI-6 and obidoxime at doses of 5% LD50 and 50% LD50, when compared to the controls. No statistical differences of Mrp2 expression were measured when animals were administered with K027 at a dose of 5% LD50 in comparison with control animals. We found impaired hepatic transporter function after administration of HI-6, obidoxime and higher concentration of K027, which might be the underlying mechanism of acetylcholinesterase reactivators' hepatotoxicity. [source] Berry anthocyanins and anthocyanidins exhibit distinct affinities for the efflux transporters BCRP and MDR1BRITISH JOURNAL OF PHARMACOLOGY, Issue 8 2009A Dreiseitel Background and purpose:, Dietary anthocyanins hold great promise in the prevention of chronic disease but factors affecting their bioavailability remain poorly defined. Specifically, the role played by transport mechanisms at the intestinal and blood,brain barriers (BBB) is currently unknown. Experimental approach:, In the present study, 16 anthocyanins and anthocyanidins were exposed to the human efflux transporters multidrug resistance protein 1 (MDR1) and breast cancer resistance protein (BCRP), using dye efflux, ATPase and, for BCRP, vesicular transport assays. Key results:, All test compounds interacted with the BCRP transporter in vitro. Of these, seven emerged as potential BCRP substrates (malvidin, petunidin, malvidin-3-galactoside, malvidin-3,5-diglucoside, cyanidin-3-galactoside, peonidin-3-glucoside, cyanidin-3-glucoside) and 12 as potential inhibitors of BCRP (cyanidin, peonidin, cyanidin-3,5-diglucoside, malvidin, pelargonidin, delphinidin, petunidin, delphinidin-3-glucoside, cyanidin-3-rutinoside, malvidin-3-glucoside, pelargonidin-3,5-diglucoside, malvidin-3-galactoside). Malvidin, malvidin-3-galactoside and petunidin exhibited bimodal activities serving as BCRP substrates at low concentrations and, at higher concentrations, as BCRP inhibitors. Effects on MDR1, in contrast, were weak. Only aglycones exerted mild inhibitory activity. Conclusions and implications:, Although the anthocyanidins under study may alter pharmacokinetics of drugs that are BCRP substrates, they are less likely to interfere with activities of MDR1 substrates. The present data suggest that several anthocyanins and anthocyanidins may be actively transported out of intestinal tissues and endothelia, limiting their bioavailability in plasma and brain. [source] Role of multidrug resistance protein 2 (MRP2) in glutathione-bimane efflux from Caco-2 and rat renal proximal tubule cellsBRITISH JOURNAL OF PHARMACOLOGY, Issue 5 2001Sylvie A Terlouw The multidrug resistance protein 2 (MRP2) has been shown to play an important role in the transport of glutathione conjugates in the liver. Its importance in renal excretion, however, is still uncertain and other organic anion transporters may be involved. The objective of the present study was to characterize glutathione conjugate efflux from rat kidney proximal tubule cells (PTC), and to determine the contribution of Mrp2. We used isolated PTC in suspension, as well as grown to monolayer density. For comparison, transport characteristics were also determined in the human intestinal epithelial cell line Caco-2, an established model to study MRP2-mediated transport. The cells were loaded with monochlorobimane (MCB) at 10°C. MCB enters the cells by simple diffusion and is conjugated with glutathione to form the fluorescent glutathione-bimane (GS-B). In primary cultures of rat PTC, no indications for a transporter-mediated mechanism were found. The efflux of GS-B from Caco-2 cells and freshly isolated PTC was time- and temperature-dependent. Furthermore, GS-B transport in both models was inhibited by chlorodinitrobenzene (CDNB), with an inhibitory constant of 46.8±0.9 ,M in freshly isolated PTC. In Caco-2 cells, the inhibitory potency of CDNB was approximately 20 fold higher. Finally, efflux of GS-B from freshly isolated PTC from Mrp2-deficient (TR,) rats was studied. As compared to normal rat PTC, transport characteristics were not different. We conclude that in freshly isolated rat PTC glutathione conjugate excretion is mediated by other organic anion transporters rather than by Mrp2. British Journal of Pharmacology (2001) 134, 931,938; doi:10.1038/sj.bjp.0704284 [source] The sulphonylurea glibenclamide inhibits multidrug resistance protein (MRP1) activity in human lung cancer cellsBRITISH JOURNAL OF PHARMACOLOGY, Issue 3 2001Léa Payen Glibenclamide, a sulphonylurea widely used for the treatment of non-insulin-dependent diabetes mellitus, has been shown to inhibit the activities of various ATP-binding cassette (ABC) transporters. In the present study, its effects towards multidrug resistance protein 1 (MRP1), an ABC efflux pump conferring multidrug resistance and handling organic anions, were investigated. Intracellular accumulation of calcein, an anionic dye substrate for MRP1, was strongly increased by glibenclamide in a dose-dependent manner in MRP1-overexpressing lung tumour GLC4/Sb30 cells through inhibition of MRP1-related calcein efflux. By contrast, glibenclamide did not alter calcein levels in parental control GLC4 cells. Another sulphonylurea, tolbutamide, was however without effect on calcein accumulation in both GLC4/Sb30 and GLC4 cells. Glibenclamide used at 12.5 ,M was, moreover, found to strongly enhance the sensitivity of GLC4/Sb30 cells towards vincristine, an anticancer drug handled by MRP1. Efflux of carboxy-2,,7,-dichlorofluorescein, an anionic dye handled by the ABC transporter MRP2 sharing numerous substrates with MRP1 and expressed at high levels in liver, was also strongly inhibited by glibenclamide in isolated rat hepatocytes. In summary, glibenclamide reversed MRP1-mediated drug resistance likely through inhibiting MRP1 activity and blocked organic anion efflux from MRP2-expressing hepatocytes. Such effects associated with the known inhibitory properties of glibenclamide towards various others ABC proteins suggest that this sulphonylurea is a general inhibitor of ABC transporters. British Journal of Pharmacology (2001) 132, 778,784; doi:10.1038/sj.bjp.0703863 [source] Pegylated liposomal doxorubicin-efficacy in patients with recurrent high-grade gliomaCANCER, Issue 6 2004Peter Hau M.D. Abstract BACKGROUND Doxorubicin exhibits high efficacy in malignant glioma cell cultures. Nonetheless, as a standard formulation, doxorubicin has not been used clinically, due to poor penetration of the blood-brain barrier. Furthermore, doxorubicin is known to induce tumor resistance genes. To address both of these issues, the authors investigated the use of pegylated liposomal doxorubicin (CaelyxÔ; Essex Pharma, Munich, Germany) alone (Trial 1) and in combination with tamoxifen (Trial 2) in two sequentially performed nonrandomized prospective Phase II trials involving patients with recurrent high-grade glioma. METHODS Twenty patients were included in each trial. Progression-free survival at 6 months (PFS-6) and toxicity were the primary endpoints. Expression of the tumor resistance proteins multidrug resistance protein 1 (MDR-1) and multiple resistance protein (MRP) was evaluated by immunohistochemical methods and by sestamibi,single-photon emission computed tomography (SPECT). RESULTS The overall response rate (including cases of disease stabilization) was 40% in both Trial 1 and Trial 2. PFS-6 was 15%, and the median time to disease progression was 17 weeks. It is noteworthy that 40% of patients with Grade III tumors had long-term responses, which lasted for up to 3 years. There was no significant difference between Trial 1 and Trial 2 in terms of efficacy. Both regimens were well tolerated, with the main side effect being palmoplantar erythrodysesthesia. The authors found no correlation between clinical response and expression of tumor resistance genes or between clinical response and SPECT data. CONCLUSIONS Pegylated liposomal doxorubicin administered alone or in combination with tamoxifen is safe and moderately effective in patients with recurrent high-grade glioma. None of the putative predictors for response that were evaluated proved to be significant in this setting. Cancer 2004. © 2004 American Cancer Society. [source] Expression of Multidrug Resistance-related Transporters in Human Breast CarcinomaCANCER SCIENCE, Issue 4 2001Atsuko Kanzaki The expression levels of mRNA for multidrug resistance 1 (MDR1) gene, multidrug resistance protein 1 (MRP1), lung resistance-related protein (LRP) and breast cancer resistance protein (BCRP), which confer multidrug resistance in vitro, were examined in 43 untreated breast carcinoma patients, of whom 38 subsequently received doxorubicin-based chemotherapy after surgery, in order to elucidate the roles of these genes in drug resistance in vivo. The mRNA levels were determined using a semi-quantitative reverse-transcription polymerase chain reaction method in breast carcinoma tissues including at least 80% carcinoma cells. The expression level of BCRP gene was low and did not vary markedly in comparison with that of MDR1, MRP1 or LRP gene. The expressions of MDR1 and MRP1 genes were correlated with each other, but the expression of BCRP or LRP gene did not correlate with that of other genes. These four gene expressions were independent of age, TNM categories and the status of progesterone or estrogen receptor. The expression levels of these four genes were not related to the relapse or prognosis of the 38 patients treated with doxorubicin-based chemotherapy. P-glycoprotein (P-gp)/MDRl, MRP1 and LRP may play more important roles than BCRP in chemotherapy of human breast carcinoma. [source] The role of surfactants in the reversal of active transport mediated by multidrug resistance proteinsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2003Katrijn Bogman Abstract A variety of seven nonionic, one amphoteric and, one anionic surfactant that are applied or investigated as surfactants in drug formulation, were analyzed for their capacity to modulate carrier-mediated transport by efflux pumps. Two cell lines, murine monocytic leukemia cells overexpressing P-glycoprotein (P-gp) and Madin-Darby canine kidney cells stably overexpresssing human multidrug resistance-associated protein 2 (MRP2), were used as test systems. The modulation of P-gp and of MRP2 function was studied by the reversal of rhodamine 123 and of methylfluorescein-glutathione conjugate transport, respectively. Mechanisms that were not transporter related and could lead to misinterpretations were identified, such as probe quenching, probe encapsulation by micelles, and membrane damage. P-gp-mediated rhodamine 123 transport was inhibited by five nonionic surfactants in a concentration-dependent manner and in the order TPGS,>,Pluronic PE8100,>,Cremophor EL,>,Pluronic PE6100,,,Tween 80. In contrast, none of the surfactants showed a significant inhibition of MRP2-mediated efflux in Madin-Darby canine kidney/MRP2 cells. In conclusion, the results indicate that surfactants demonstrate a transporter-specific interaction, rather than unspecific membrane permeabilization. The present analysis offers insight in the possible mechanisms of surfactant interactions with biological membranes and could help to identify specific drug formulations. © 2003 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 92:1250,1261, 2003 [source] | ||||||||||||||||||||||||||||