The aim of this study was to investigate the effect of intracellular acidification on the P-gp in K562/A02 cells. Confocal laser microscope was used to determine the intracellular acidification. MTT assay was used to detect the cytotoxicity of intracellular acidification on K562 and K562/A02 cells. Flow cytometry was applied to measure the influence of intracellular acidification on the activity of P-gp. The P-gp expression at protein and mRNA levels were determined by Western blot and real-time RT-PCR respectively. The results indicated that intracellular acidification had no obvious cytotoxicity on K562 and K562/A02 cells. The function of P-gp in K562/A02 cells weakened along with decrease of intracellular acidification, the intracellular acidification significantly increased the accumulation of Rhodamine 123 (Rh 123) and suppressed the efflux of Rh 123 mediated by P-gp. The intracellular acidification also inhibited the expression of P-gp in K562/A02 cells at protein and mRNA levels which showed intracellular acidification with time-dependence. It is concluded that the intracellular acidification can inhibit the expression and function of P-gp in K562/A02 cells.
ATP Binding Cassette Transporter, Sub-Family B ; ATP-Binding Cassette, Sub-Family B, Member 1 ; metabolism ; Drug Resistance, Multiple ; Drug Resistance, Neoplasm ; Humans ; Hydrogen-Ion Concentration ; K562 Cells

ATP Binding Cassette Transporter, Sub-Family B ; genetics ; Cholestasis, Intrahepatic ; classification ; genetics ; Humans

ATP Binding Cassette Transporter, Sub-Family B ; metabolism ; Animals ; Anticonvulsants ; pharmacology ; Brain ; drug effects ; metabolism ; Rats

<b>OBJECTIVEb>To 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.

<b>METHODSb>Immunohistochemistry 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.

<b>RESULTSb>Compared 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) .

<b>CONCLUSIONb>Chemotherapy 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

<b>OBJECTIVEb>To investigate the correlation of MDR1 and ABCG2 genetic polymorphisms with the efficacy and adverse events of irinotecan chemotherapy in patients with colorectal cancer (CRC).

<b>METHODSb>Clinical 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.

<b>RESULTSb>Allele 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.

<b>CONCLUSIONb>MDR1 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

<b>OBJECTIVEb>To investigate the expression of multidrug resistance gene ABCB1 and ABCG2 in FaDu cells (human hypopharyngeal carcinoma cell line) and the multidrug resistance (MDR) cell lines FaDu/T transformed from FaDu cells by taxol and underlying mechanisms of MDR.

<b>METHODSb>The multidrug resistance sensitivities of FaDu and FaDu/T to cisplatin (DDP), 5-fluorouracil (5-FU), doxorubicin (Dox), and vincristine (VCR) were examined by methyl-thiazolyl-tetrazolium (MTT) assay. The mRNA and protein expressions of multidrug resistance genes ABCB1 and ABCG2 were analysed with RT-PCR, Western blot and laser confocal microscopy. JNK signal proteins were detected through Western blot.

<b>RESULTSb>The multidrug resistance of FaDu/T cells to Taxol, DDP, 5-FU, ADM and VCR was more than that of FaDu cells. The expression of ABCB1 in FaDu/T cells was significantly higher than that in FaDu cells (t = 22.42, P < 0.05), but the expression of ABCG2 in FaDu/T cells was significantly lower than that in FaDu cells (t = 10.06, P < 0.05). JNK signal was inhibited in FaDu or FaDu/T cells and the inhibited JNK was reactivated by taxol or anisomycin (an activator for MAPK signal transduction pathways). Anisomycin down-regulated the expression of ABCB1 (F = 33.72, P < 0.05) and up-regulated the expression of ABCG2 (F = 220.16, P < 0.05) in FaDu/T cells, but not in FaDu/T cells pretreated by JNK inhibitor SP600125 (P > 0.05).

<b>CONCLUSIONb>The overexpression of ABCB1 and the down-regulation of ABCG2 in FaDu/T cells were the main features of MDR in hypopharyngeal carcinomas, in which JNK signal transduction pathways could play an important role.

ATP Binding Cassette Transporter, Sub-Family B ; ATP-Binding Cassette Sub-Family B Member 2 ; ATP-Binding Cassette Transporters ; genetics ; ATP-Binding Cassette, Sub-Family B, Member 1 ; genetics ; Cell Line, Tumor ; Drug Resistance, Multiple ; genetics ; Drug Resistance, Neoplasm ; genetics ; Humans ; Hypopharyngeal Neoplasms ; genetics

The study was aimed to explore the NF-kappaB continual activity and the expression of WT1 and MDR1 in acute non-lymphocytic leukemia (ANLL) patients, and to investigate if the three factors affect the curative effect of ANLL together as to provide some theoretical basis for finding new measures to improve the curative effect of refractory ANLL. The bone marrow samples of 45 ANLL patients was collected. 45 patients including 20 primary ANLL patients (A group) and 25 refractory ANLL patients. Refractory ANLL patients were divided into 2 sub-groups (B, C groups). The primary patients who was no effect after more than two courses of treatment were taken as group B, and the patients with more than two relapses were taken as group C. At the same time, 15 patients with simple iron deficiency anemia were collected as negative control. The NF-kappaB continual activity was measured by using electrophoretic mobility shift assay (EMSA) and the expressions of WT1, MDR1 were detected by reverse transcriptase polymerase chain reaction (RT-PCR). The results showed that the activity of NF-kappaB and the expressions of WT1, MDR1 were not detected in 15 samples of simply iron deficiency anemia subjects. The NF-kappaB continual activity, the expression levels of WT1 and MDR1 in the refractory group were significantly higher than that in primary group (P<0.001). But the NF-kappaB continual activity, the expression of WT1 gene and MDR1 gene were not significantly different between group B and group C (P>0.05). By assaying the relativity between the them the NF-kappaB continual activity and the expression of WT1 or MDR1 had positive correlation in ANLL patients. It is concluded that the NF-kappaB continual activity, the overexpression of WT1 and MDR1 may be one of the reasons causing poor curative effect in acute non-lymphocytic leukemia. The NF-kappaB continual activity and the expression of WT1, MDR1, all show positive correlation in ANLL patients.
ATP Binding Cassette Transporter, Sub-Family B ; ATP-Binding Cassette, Sub-Family B, Member 1 ; biosynthesis ; genetics ; Female ; Humans ; Leukemia, Myeloid, Acute ; genetics ; metabolism ; Male ; NF-kappa B ; metabolism ; WT1 Proteins ; biosynthesis ; genetics

<b>OBJECTIVEb>To investigate the effect of tetrandrine (TTD) on doxorubicin-induced mdr1 gene expression and its mechanism.

<b>METHODSb>MTT assay was used to detect the cytotoxicity of TTD to K562 cells. K562 cells were treated with doxorubicin alone or 0.6 microg/ml doxorubicin combined with various concentrations of TTD. RT-PCR was used to detect the mRNA expression of mdr1 and NF-kappa B. Flow cytometry was used to assay the expression of P-glycoprotein (P-gp). Intracellular rhodamine 123 (Rho123) retention assay was applied to test the P-gp function.

<b>RESULTSb>After treatment with 0.6 microg/ml doxorubicin for 24 hours, the expressions of mdr1 mRNA, NF-kappa B mRNA and P-gp in K562 cells were increased from 0.171 +/- 0.012, 0.783 +/- 0.090, 7.85 +/- 0.15 to 0.428 +/- 0.012, 1.075 +/- 0.047 and 73.68 +/- 1.84, respectively. The intracellular Rho123 retention was decreased from 711.9 +/- 63.6 to 347.8 +/- 60.6, indicating up-regulation of P-gp function (P<0.05). Pretreatment of K562 cells with 2.0 microg/ml TTD for 24 hours and then incubated for another 24 h with doxorubicin, the expressions of mdr1 mRNA, NF-kappa B mRNA, P-gp and up-regulation of P-gp function induced by doxorubicin were prevented in K562 cells (0.148 +/- 0.006, 0.627 +/- 0.098, 7.18 +/- 0.38 and 799.7 +/- 45.8, respectively P<0.05). But 0.5 microg/ml and 1.0 microg/ml TTD had little effect.

<b>CONCLUSIONSb>TTD inhibits the expression of mdr1 mRNA, P-gp and up-regulated P-gp function induced by doxorubicin in a dose dependent manner. The mechanism of this effect may be down-regulation of NF-kappa B by TTD.

ATP Binding Cassette Transporter, Sub-Family B ; ATP-Binding Cassette, Sub-Family B, Member 1 ; genetics ; metabolism ; Benzylisoquinolines ; pharmacology ; Doxorubicin ; pharmacology ; Humans ; K562 Cells ; NF-kappa B ; metabolism ; RNA, Messenger ; genetics ; Up-Regulation ; drug effects

Drug metabolism will change significantly during inflammation, including the reduction of expression and activity of many drug metabolizing enzymes and transporters. Body would release a series of inflammatory cytokines which can regulate drug metabolizing enzymes. Recent studies have revealed that drug transporters are also regulated by the cytokines with obvious species difference. Mechanism studies show that several transcription factors play important roles during the signal pathways of regulation. This review focuses on the progress in the regulation of drug transporters during inflammation.
ATP Binding Cassette Subfamily B Member 11 ; ATP Binding Cassette Transporter, Sub-Family B ; metabolism ; ATP Binding Cassette Transporter, Sub-Family G, Member 2 ; ATP-Binding Cassette Transporters ; metabolism ; Animals ; Biological Transport ; Humans ; Inflammation ; metabolism ; Membrane Transport Proteins ; metabolism ; Multidrug Resistance-Associated Proteins ; metabolism ; Neoplasm Proteins ; metabolism ; Organic Anion Transporters ; metabolism ; Organic Cation Transport Proteins ; metabolism ; Signal Transduction

<b>OBJECTIVEb>To explore the impact of extracellular acidic environment on the expression and activity of P-glycoprotein (P-gp) and on the P-gp-mediated cytotoxicity of daunomycin in cancer cells by using microfluidic chip technology.

<b>METHODSb>The A549 cells cultured on a microfluidic chip were divided into experiment group and control group. The experiment group was exposed to an acidic cell culture medium (pH 6.6), while the control group was treated with a neutral cell culture medium (pH 7.4). The expression of P-gp was detected by cell immunofluorescense analysis and the activity of P-gp was evaluated by Rhodamine 123 efflux experiment. Meanwhile, the cytotoxicity of daunomycin was analyzed by cell live/dead fluorescence staining method.

<b>RESULTSb>Microfluidic chip designed in this study could provide a suitable microenvironment for the growth of A549 cells and the A549 cells reached the confluence of 90% after inoculation for 72 h. Treatment of the acidic cell culture media on A549 cells did not make a significant difference on the expression level of P-gp. However, the activity of P-gp was significantly enhancement and peaked at 6 h after treatment with acidic cell culture media. Meanwhile, the cytotoxicity of daunomycin reduced significantly after treatment with acidic cell culture medium for 6 h,and a reversal effect was obtained when synergy with verapamil.

<b>CONCLUSIONSb>Microfluidic chip technology can shorten the analysis time and reduce the reagent consumption. It can be used as a new technology platform for understanding the mechanisms of multi-drug resistance and for screening highly efficient multi-drug resistance reversal agents.

ATP Binding Cassette Transporter, Sub-Family B ; ATP-Binding Cassette, Sub-Family B, Member 1 ; Cell Culture Techniques ; Cell Line, Tumor ; Culture Media ; Daunorubicin ; Extracellular Space ; Humans ; Hydrogen-Ion Concentration ; Microfluidics