ATP Binding Cassette Subfamily B Member 11 ; ATP Binding Cassette Transporter, Sub-Family G, Member 2 ; ATP-Binding Cassette Transporters ; physiology ; ATP-Binding Cassette, Sub-Family B, Member 1 ; physiology ; Animals ; Bile ; metabolism ; Biliary Tract ; physiology ; Drug Interactions ; Drug Resistance, Multiple ; Humans ; Liver ; physiology ; Multidrug Resistance-Associated Proteins ; physiology ; Neoplasm Proteins ; physiology ; Organic Anion Transporters ; physiology ; Organic Anion Transporters, Sodium-Dependent ; physiology ; Organic Cation Transport Proteins ; physiology ; Symporters ; physiology

<p>OBJECTIVETo evaluate the use of protein array chips in detection of multidrug-resistance proteins.p><p>METHODSHuman erythroleukemic cell line K562 and its doxorubicin-resistant counterpart K562/A02 were used in the study. Monoclonal antibodies against P-glycoprotein (P-gP), multidrug resistance-associated protein (MRP1) and breast cancer resistance protein (BCRP) were immobilized onto agarose film-coated glass. The antibody-cell binding was assessed by capturing K562 and K562/A02 cells. The protein array was observed under a microscope and the image was captured with a CCD camera. The expression levels of the three proteins were also measured by flow cytometry (FCM).p><p>RESULTSThe expression of P-gP and BCRP in K562 was very low. However, MRP1 expression was high. P-gP and MRP1 were highly expressed in K562/A02, while the expression of BCRP was low. FCM results showed that the expression rate of P-gP, MRP1 and BCRP in K562 cells was 5.98% +/- 2.19%, 95.80% +/- 3.98%, 1.03% +/- 0.45%, respectively, while that in K562/A02 cells was 92.67% +/- 1.80%, 97.18% +/- 1.02%, 3.98% +/- 0.37%, respectively. The results of protein array method are consistent with those of FCM (P > 0.05).p><p>CONCLUSIONIt is feasible to develop a new protein array technique and to provide a novel method for multi-drug resistant cell detection, with a high throughput, high specificity, simple procedure and low cost.p>
ATP Binding Cassette Transporter, Sub-Family G, Member 2 ; ATP-Binding Cassette Transporters ; analysis ; ATP-Binding Cassette, Sub-Family B, Member 1 ; analysis ; Drug Resistance, Multiple ; genetics ; Drug Resistance, Neoplasm ; genetics ; Humans ; K562 Cells ; Multidrug Resistance-Associated Proteins ; analysis ; Neoplasm Proteins ; analysis ; Protein Array Analysis

The aim of this study was to investigate the mechanism to reverse the drug resistance of leukemia cells in tetrandrine (Tet) alone or in combination with droloxifen (Drol) by using protein chips and to lay the theoretical basis for the clinical applications. Three monoclonal antibodies against P-glycoprotein (P-gp), the multidrug resistance-associated protein (MRP1) and the breast cancer resistance protein (BCRP) were immobilized onto the agarose gel film-coated glass slides. Protein chips were prepared respectively from K562/A02 cells cultured for 12, 24 and 48 hours with Tet alone or in combination with Drol. The results showed that Tet alone or in combination with Drol could decrease only the expression of P-gp in a time-dependent manner, the effect for 48 hours as follows: Tet + Drol 82.620 +/- 3.227; Tet alone 86.440 +/- 2.906; Drol alone 87.230 +/- 2.049; control 93.670 +/- 2.748 (P < 0.05). However, down-regulation of P-gp by K562/A02 cells cultured with Tet alone or in combination with Drol began at 24 hours (Tet + Drol 85.270 +/- 3.095; control 93.670 +/- 2.748, P < 0.05). The results were coincident with that of FCM. It is concluded that Tet and Drol can downregulate the expression of P-gp in the time-dependent way. There is a significant difference between Tet alone and Tet combined with Drol at 24 hours (P < 0.05). The expression of MRP1 and BCRP are not closely correlated with the reversal mechanism of Tet and Drol, and which may be involved in the mechanism of this combination to reverse multidrug resistance in leukemia.
ATP Binding Cassette Transporter, Sub-Family G, Member 2 ; ATP-Binding Cassette Transporters ; biosynthesis ; ATP-Binding Cassette, Sub-Family B, Member 1 ; biosynthesis ; Antineoplastic Agents ; pharmacology ; Benzylisoquinolines ; pharmacology ; Drug Resistance, Multiple ; Drug Resistance, Neoplasm ; drug effects ; Drug Synergism ; Humans ; K562 Cells ; Leukemia ; metabolism ; pathology ; Multidrug Resistance-Associated Proteins ; biosynthesis ; Neoplasm Proteins ; biosynthesis ; Protein Array Analysis ; Tamoxifen ; analogs & derivatives ; pharmacology

Multidrug resistance (MDR) in cancer cells can significantly attenuate the response to chemotherapy and increase the likelihood of mortality. The major mechanism involved in conferring MDR is the overexpression of ATP-binding cassette (ABC) transporters, which can increase efflux of drugs from cancer cells, thereby decreasing intracellular drug concentration. Modulators of ABC transporters have the potential to augment the efficacy of anticancer drugs. This editorial highlights some major findings related to ABC transporters and current strategies to overcome MDR.
ATP Binding Cassette Transporter, Sub-Family G, Member 2 ; ATP-Binding Cassette Transporters ; antagonists & inhibitors ; metabolism ; ATP-Binding Cassette, Sub-Family B, Member 1 ; antagonists & inhibitors ; metabolism ; Antineoplastic Agents ; therapeutic use ; Drug Resistance, Multiple ; Drug Resistance, Neoplasm ; Humans ; Molecular Targeted Therapy ; Multidrug Resistance-Associated Proteins ; antagonists & inhibitors ; metabolism ; Nanomedicine ; Neoplasm Proteins ; antagonists & inhibitors ; metabolism ; Neoplasms ; drug therapy ; metabolism ; Protein-Tyrosine Kinases ; antagonists & inhibitors

Multidrug regimens and corresponding drug interactions cause many adverse reactions and treatment failures. Drug efflux transporters: P-glycoprotein (P-gp), multidrug resistance associated protein (MRP) and breast cancer resistance protein (BCRP) in conjunction with metabolizing enzymes (cytochrome P450, CYP450) are major factors in such interaction. In recent years, a large number of studies have shown that P-gp plays a role in the oxidative metabolism of its substrates that are also substrates of CYP3A4. Combined actions of P-gp and CYP3A could account in some part for the low oral bioavailability determined for many of these dual substrates. P-gp along with efflux transporters (MRP and BCRP) having overlapping substrate specificity plays critical role in drug disposition. The relationship between MRP or BCRP and CYP3A is similar to that between P-gp and CYP3A. In this paper, we summarize the classification of efflux transporters, the main metabolizing enzymes CYP3A, clinical significance interactions mediated by efflux transporters and CYP450 enzymes and in vitro studies.
ATP Binding Cassette Transporter, Sub-Family G, Member 2 ; ATP-Binding Cassette Transporters ; metabolism ; ATP-Binding Cassette, Sub-Family B, Member 1 ; metabolism ; Biological Availability ; Cytochrome P-450 CYP3A ; metabolism ; Cytochrome P-450 Enzyme System ; metabolism ; Drug Interactions ; Humans ; Multidrug Resistance-Associated Proteins ; metabolism ; Neoplasm Proteins ; metabolism ; Substrate Specificity

<p>OBJECTIVELiver regeneration occurs through hepatocytes after acute liver injury. However, severe liver injury activates bipotential oval cells from canals of Hering which can differentiate into hepatocytes and biliary epithelial cells. Most models of oval cell activation have employed potential carcinogens to inhibit hepatocyte replication in the face of a regenerative stimulus. Oval cells must be able to withstand the toxic milieu of the damaged liver. ATP binding cassette transporters are cytoprotective efflux pumps that may contribute to the protection of these cells. The aim of this study was to determine the ABC transporter expressions in hepatic oval cells.p><p>METHODSA rat model was established by feeding 2-acetylaminofluorene combined with partial hepatectomy to activate hepatic oval cells. Oval cells were isolated and purified using selective enzymatic digestion and density gradient centrifugation from the heterogeneous hepatic cell population. The expressions of ABC transporter gene, including MDR1, MRP1 and Bcrp1, in isolated hepatic oval cells and hepatocytes were measured by quantitative real-time reverse transcription-polymerase chain reaction and those in rat liver tissues were measured by immunohistochemistry.p><p>RESULTSCompared to those in the rat hepatocytes, mRNA expressions of the genes encoding MDR1, MRP1 and Bcrp1 were increased up to 9-, 1.5- and 13.8-folds in hepatic oval cells. Immunohistochemical staining of rat liver slides demonstrated that the expression of MDR1 proteins was found around periportal areas, and Bcrp1 protein was found located on cell membranes.p><p>CONCLUSIONHepatic oval cells express high levels of the ABC transporter gene that may have cytoprotective functions during severe hepatotoxicity.p>
ATP Binding Cassette Transporter, Sub-Family G, Member 2 ; ATP-Binding Cassette Transporters ; genetics ; metabolism ; ATP-Binding Cassette, Sub-Family B, Member 1 ; genetics ; Animals ; Cell Line ; Hepatectomy ; Hepatocytes ; cytology ; metabolism ; Liver Regeneration ; Male ; Multidrug Resistance-Associated Proteins ; genetics ; RNA, Messenger ; genetics ; Rats ; Rats, Sprague-Dawley

Liver is regarded as one of the most important organs for drug clearance in the body, which mediates both the metabolism and biliary excretion of drugs. Transporters are a class of functional membrane proteins and control the movement of substances into or out of cells. Transporters, which are extensively expressed in the liver, play important roles in the drug hepatic disposition by regulating the uptake of drugs from blood into hepatocytes or the efflux of drugs and their metabolites into bile. In this review, the localization, functions and substrate selectivity of the major transporters in the liver will be summarized, and the impacts of these transporters on drug hepatic disposition, the potential drug-drug interactions as well as their genetic polymorphisms will also be reviewed.
ATP Binding Cassette Transporter, Sub-Family G, Member 2 ; ATP-Binding Cassette Transporters ; genetics ; metabolism ; ATP-Binding Cassette, Sub-Family B, Member 1 ; genetics ; metabolism ; Bile ; metabolism ; Biological Transport ; Drug Interactions ; Humans ; Liver ; metabolism ; Membrane Transport Proteins ; genetics ; metabolism ; Metabolic Clearance Rate ; Multidrug Resistance-Associated Proteins ; genetics ; metabolism ; Neoplasm Proteins ; genetics ; metabolism ; Organic Anion Transporters ; genetics ; metabolism ; Organic Anion Transporters, Sodium-Dependent ; metabolism ; Organic Anion Transporters, Sodium-Independent ; genetics ; metabolism ; Organic Cation Transport Proteins ; genetics ; metabolism ; Pharmacokinetics ; Polymorphism, Genetic ; Symporters ; metabolism

The formation of macrophage-derived foam cells is a typical feature of atherosclerosis (AS). Reverse cholesterol efflux (RCT) is one of important factors for the formation of macrophage foam cells. In this study, macrophage form cells were induced by oxidized low density lipoprotein (ox-LDL) and then treated with different concentrations of ferulic acid, so as to observe the effect of ferulic acid on the intracellular lipid metabolism in the ox-LDL-induced macrophage foam cell formation, the cholesterol efflux and the mRNA expression and protein levels of ATP binding cassette transporter A1 (ABCA1) and ATP binding cassette transporter G1 (ABCG1) that mediate cholesterol efflux, and discuss the potential mechanism of ferulic acid in resisting AS. According to the findings, compared with the control group, the ox-LDL-treated group showed significant increase in intracellular lipid content, especially for the cholesterol content; whereas the intracellular lipid accumulation markedly decreased, after the treatment with ferulic acid. The data also demonstrated that the mRNA and protein expressions of ABCA1 and ABCG1 significantly increased after macrophage foam cells were treated with different concentrations of ferulic acid. In summary, ferulic acid may show the anti-atherosclerosis effect by increasing the surface ABCA1 and ABCG1 expressions of macrophage form cells and promoting cholesterol efflux.
ATP Binding Cassette Transporter 1 ; analysis ; genetics ; ATP Binding Cassette Transporter, Sub-Family G, Member 1 ; ATP-Binding Cassette Transporters ; analysis ; genetics ; Animals ; Cells, Cultured ; Cholesterol ; metabolism ; Coumaric Acids ; pharmacology ; Foam Cells ; drug effects ; metabolism ; Lipoproteins ; analysis ; genetics ; Mice

<p>OBJECTIVETo identify the mutational genotype of three Chinese families with X-linked adrenoleukodystrophy (X-ALD: MIM#300100).p><p>METHODSTotal RNA was extracted from the peripheral blood leukocytes of patients 1, 2 and the mother of patient 3, using RNA blood Mini kit (QIAGEN). After reverse transcription, cDNA was amplified in four overlapping segments. The PCR products were purified and directly sequenced. To confirm the mutations, the genomic DNA was isolated from the patients and their family members using DNA blood isolation kit (MO-BIO) and analyzed by PCR-restrictive digestion or amplification refractory mutation system.p><p>RESULTSThree distinct mutations were detected in the ABCD1 gene of the three pedigrees. A mutation of CCC-->CGC was detected at codon 534 of the ABCD1 gene from patient 1, resulting in the arginine for proline substitution. A change of GGG-->AGG was found at codon 266 of the second patient's gene, accompanied with the replacement of glycine by arginine. A mutation of CGC-->GGC was found at codon 617 in one ABCD1 allele of the third patient's mother, leading to the glycine for arginine substitution. The three mutations were confirmed through restriction analysis or amplification refractory mutation system.p><p>CONCLUSIONThree ABCD1 gene missense mutations were detected in three unrelated Chinese families with X-linked adrenoleukodystrophy, one of which, the mutation (P534R), is novel in Chinese with ALD, and the other two G266R and R617G mutations, have been reported outside China.p>
ATP Binding Cassette Transporter, Sub-Family D, Member 1 ; ATP-Binding Cassette Transporters ; genetics ; Adrenoleukodystrophy ; genetics ; Child ; Child, Preschool ; Humans ; Male ; Mutation ; Pedigree

<p>OBJECTIVETo study the effects of high-density lipoprotein (HDL) and oxidized high-density lipoprotein (ox-HDL) on the expression of ATP-binding cassette transporter A1 (ABCAl) and cholesterol efflux in human umbilical vein endothelial cells (HUVECs).p><p>METHODSIn vitro cultured HUVECs were incubated in the presence of 100 microg/ml HDL or 100 microg/ml ox-HDL for 24 h, using PBS as the negative control. ABCA1 mRNA level and cholesterol efflux rate were determined using RT-PCR and a liquid scintillator, respectively.p><p>RESULTSHDL and ox-HDL significantly elevated the level of ABCA1 mRNA by 58% and 23% relative to the control level, respectively (P<0.05). The cholesterol efflux rate in ox-HDL group was significantly lower than that in HDL group (P<0.01).p><p>CONCLUSIONHDL increases ABCAl expression and cholesterol efflux in HUVECs. Oxidative modification of HDL decrease cholesterol efflux by inhibiting the expression of ABCAl, suggesting a possible mechanism of ox-HDL in the pathogenesis of atherosclerosis.p>
ATP Binding Cassette Transporter 1 ; ATP-Binding Cassette Transporters ; genetics ; metabolism ; Cells, Cultured ; Cholesterol ; metabolism ; Endothelial Cells ; metabolism ; Humans ; Lipoproteins, HDL ; metabolism ; physiology ; Umbilical Veins ; cytology