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

OBJECTIVETo compare the expression differences of breast cancer resistance protein(BCRP/ABCG2) and P-glycoprotein(P-gp) in breast cancer tissue before chemotherapy and in residual breast cancer tissue, and to explore its correlation with breast cancer stem cells.

METHODSImmunohistochemistry was used to detect the expression of ABCG2, P-gp, and breast cancer stem cells(BCSCs) markers(CD44 and CD24) in breast cancer tissue before chemotherapy and residual breast cancer tissue after chemotherapy. Immunofluorescence was applied for determination of the CD44 and CD24 protein expressions of BCSCs microspheres cells. The monoclone-forming ability of BCSCs microspheres cells was detected by limited dilution assay. The expressions of ABCG2, P-gp, CD44, and CD24 proteins were detected by Western blot.

RESULTSCompared with those in breast cancer tissue before chemotherapy, the expression levels of ABCG2 and P-gp were positively correlated with the expression level of CD44 protein(Χ(2)=41.34, r=0.83;Χ(2)=22.81, r=0.61) in residual breast cancer tissue after chemotherapy;meanwhile, they were negatively correlated with the expression of CD24 protein(Χ(2)=-21.25, r=0.72;Χ(2)=-17.26, r=0.65) (all P<0.05) .The diameter of BCSCs microspheres were increased significantly after chemotherapy.The content of BCSCs increased by about 2.5 times after chemotherapy.The expressions of ABCG2, P-gp and CD44 proteins significantly increased and that of CD24 protein significantly declined(P<0.05) .

CONCLUSIONChemotherapy endows residual breast cancer tissue with cancer stem cells-like features, leading to multidrug resistance of breast cancer.

ATP Binding Cassette Transporter, Sub-Family B ; ATP Binding Cassette Transporter, Sub-Family G, Member 2 ; ATP-Binding Cassette Transporters ; metabolism ; ATP-Binding Cassette, Sub-Family B, Member 1 ; metabolism ; Adult ; Aged ; Breast Neoplasms ; drug therapy ; metabolism ; CD24 Antigen ; metabolism ; Cell Culture Techniques ; Drug Resistance, Neoplasm ; Female ; Humans ; Hyaluronan Receptors ; metabolism ; Middle Aged ; Neoplasm Proteins ; metabolism ; Neoplasm, Residual ; Neoplastic Stem Cells ; cytology ; metabolism

OBJECTIVETo investigate the correlation of MDR1 and ABCG2 genetic polymorphisms with the efficacy and adverse events of irinotecan chemotherapy in patients with colorectal cancer (CRC).

METHODSClinical data of CRC patients treated with irinotecan-based chemotherapy in the Peking University Cancer Hospital between January 1996 and December 2011 were collected, and their blood samples were collected accordingly. Genomic DNA was extracted from blood samples. The following SNP detection of MDR1 and ABCG2 genes was conducted by direct sequencing method. The correlation of genetic SNPs with efficacy and toxicity of irinotecan treatment was further analyzed.

RESULTSAllele frequencies of MDR1 2677 G>T/A, ABCG2 421 C>A, 34 G>A, 376 C>T were comparable with previous studies. Genetic SNPs results from peripheral blood samples and tumor tissues were highly consistent. Patients carrying MDR1 2677 wild type had higher clinical benefit than those carrying mutant genotype, while the differences were not significant. The progression-free survival (PFS) was longer in wild-type patients as compared to mutant-type patients in second-line chemotherapy (P=0.012). There were no significant correlations between ABCG2 421 C>A, 34 G>A, 376 C>T and chemotherapy efficacy. No significant correlations were observed between MDR1 2677 G>T/A, ABCG2 421 C>A, ABCG2 34 G>A, ABCG2 376 C>T and irinotecan-related grade 3 and 4 neutropenia or diarrhea.

CONCLUSIONMDR1 2677 G>T/A may be served as a biomarker in predicting the efficacy of irinotecan chemotherapy in patients with colorectal cancer.

ATP Binding Cassette Transporter, Sub-Family B ; ATP Binding Cassette Transporter, Sub-Family G, Member 2 ; ATP-Binding Cassette Transporters ; genetics ; ATP-Binding Cassette, Sub-Family B, Member 1 ; genetics ; Adult ; Aged ; Camptothecin ; analogs & derivatives ; therapeutic use ; Colorectal Neoplasms ; drug therapy ; genetics ; Female ; Humans ; Male ; Middle Aged ; Neoplasm Proteins ; genetics ; Polymorphism, Single Nucleotide ; Retrospective Studies ; Treatment Outcome ; Young Adult

OBJECTIVETo investigate the role of ATP-binding cassette transporter G1 (ABCG1) in endothelial dysfunction induced by high glucose.

METHODSHuman aortic endothelial cells (HAECs) were incubated in the presence of 5.6 or 30 mmol/L glucose for 24-72 h with or without a 2-h pretreatment with the LXR agonist 22(R)-hydroxycholesterol. Real-time PCR and Western blotting were used to measure the mRNA and protein expressions of ABCG1; the intracellular cholesterol efflux and endothelial nitric oxide synthase (eNOS) activity were measured by scintillation counting.

RESULTSHigh glucose time-dependently suppressed ABCG1 expression and cholesterol efflux to HDL in HAECs. High glucose also decreased eNOS activity. ABCG1 down-regulation induced by high glucose, along with decreased cholesterol efflux and eNOS activity, was abolished by treatment of the cells with the LXR agonist.

CONCLUSIONEndothelial dysfunction induced by high glucose is associated with decreased ABCG1 expression.

ATP Binding Cassette Transporter, Sub-Family G, Member 1 ; ATP-Binding Cassette Transporters ; genetics ; metabolism ; Aorta ; cytology ; Cell Line ; Down-Regulation ; drug effects ; Endothelial Cells ; cytology ; metabolism ; physiology ; Glucose ; pharmacology ; Humans

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.

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.

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.

CONCLUSIONHepatic oval cells express high levels of the ABC transporter gene that may have cytoprotective functions during severe hepatotoxicity.

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

OBJECTIVETo evaluate the use of protein array chips in detection of multidrug-resistance proteins.

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).

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).

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.

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 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

OBJECTIVETo study the mechanism of topotecan (TPT) resistance in ovarian cancer cell line.

METHODSA TPT-resistant ovarian cancer cell line A2780/TPT established in this laboratory was used in this study. Intracellular rhodamine fluorescence intensity of the TPT-resistant cells and parental cells were measured by flow cytometry. The gene expression of membrane protein transporter such as transporter P-glycoprotein (P-gp), multidrug resistance associated protein (MRP), breast cancer resistance protein (BCRP) was evaluated by RT-PCR. The antisense-phosphorothioate oligonucleotide (ASODN) including a translation initiation site of BCRP mRNA was transferred into resistant cells by liposome.

RESULTSIntracellular rhodamine fluorescence intensity of the resistant cells was 31.19% of that in the parental cells (P < 0.01). No expression of P-gp was demonstrated, and that of MRP was very weak in the TPT-resistant cells (relative expression value = 0.057). BCRP was overexpressed in the TPT-resistant cells (relative expression = 0.66), but not in the parental cells. Transfer of ASODN into resistant cells resulted in a 59.42% reduction of BCRP gene expression (P < 0.05) and an obviously increased intracellular rhodamine fluorescence intensity from 5.42 to 16.63 (P < 0.05).

CONCLUSIONThe overexpression of BCRP which mediated drug efflux may play an important role in the induction of TPT-resistance in ovarian cancer.

ATP Binding Cassette Transporter, Sub-Family G, Member 2 ; ATP-Binding Cassette Transporters ; genetics ; ATP-Binding Cassette, Sub-Family B, Member 1 ; genetics ; Antineoplastic Agents ; pharmacology ; Cell Line, Tumor ; Drug Resistance, Neoplasm ; Female ; Humans ; Neoplasm Proteins ; genetics ; Ovarian Neoplasms ; drug therapy ; pathology ; RNA, Messenger ; analysis ; Topotecan ; 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