OBJECTIVETo investigate the effect of 5-fluorouracil (5-FU) on the expression of ATP-binding cassette superfamily G member 2 (ABCG2) in human colon cancer cell SW480.

METHODSSW480 cells were treated with various concentrations of 5-FU. CCK8 assay was utilized to detect the 5-FU IC50 to SW480 cells. Positive expression of ABCG2 was detected by flow cytometry, and mRNA expression of ABCG2 was detected by real time polymerase chain reaction (RT-PCR).

RESULTSThe 5-FU IC50 to SW480 cells increased as the drug concentration increased (P<0.05). Flow cytometry revealed that positive expression rate of ABCG2 in normal SW480 cells (group A) was (6.26±0.86)%. Immediately after treatment with 5-FU for 48 hours, the positive expression rate of ABCG2 (group B) was (3.43±1.18)% (P<0.05). In the second passage of cells after treatment with 5-FU for 48 hours, the positive expression rate of ABCG2 (group C) was (12.91±3.42)% (P<0.05). The mRNA expression of ABCG2 detected by RT-PCR was in accordance with the results from flow cytometry.

CONCLUSIONExpression of ABCG2 in SW480 cells can be affected by various concentrations of 5-FU.

ATP Binding Cassette Transporter, Sub-Family G, Member 2 ; ATP-Binding Cassette Transporters ; metabolism ; Cell Line, Tumor ; Colonic Neoplasms ; metabolism ; Fluorouracil ; pharmacology ; Humans ; Neoplasm Proteins ; 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 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

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

ABCG2, a half-transporter concerning with the endo and exon-toxin-efflux, plays an important role in protecting the normal tissues from the toxin-hurt as well as mediating the multidrug resistance, because many of the chemotherapeutic drugs are the substrate of ABCG2. In this paper, the advance of research about this gene's single nucleotide polymorphisms (SNPs) was explained concisely. The relationship among ABCG2, the stem cells and the tyrosine kinase inhibitor (TKI) was reviewed. The research about drug resistance related-progress in hematologic malignancies was analyzed retrospectively and the present problems and the perspective in the future were discussed.
ATP Binding Cassette Transporter, Sub-Family G, Member 2 ; ATP-Binding Cassette Transporters ; genetics ; Drug Resistance, Multiple ; genetics ; Drug Resistance, Neoplasm ; genetics ; Humans ; Neoplasm Proteins ; genetics ; Polymorphism, Single Nucleotide

In order to investigate the relationship between the expression of breast cancer resistance protein (BCRP) gene and drug resistance in patients with acute leukemia (AL), semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to examine the expression of BCRP mRNA in AL patients and 15 normal subjects. Beta(2)-microglobin (beta(2)-MG) was used as positive reference. BCRP/beta(2)-MG ratio >or= 0.5 was defined as BCRP mRNA positive. The results showed that the positive percentage of BCRP gene expression in newly diagnosed group was 37.6%. The first complete remission rate was 79.3% and 31.6% in BCRP mRNA negative and BCRP mRNA positive patients respectively. The difference was significant (P = 0.001). The expression levels of BCRP mRNA in drug resistance group and drug sensitive group were 0.962 +/- 0.426 and 0.315 +/- 0.296 respectively (P = 0.0001). The expression level of BCRP mRNA in relapsed/refractory group was significantly higher than that in newly diagnosed group (P = 0.0025). The expression level of BCRP gene in normal individuals and long-term survival group was very low and correlated with FAB subtypes. It is concluded that high expression of BCRP mRNA leads to clinical drug resistance and is an unfavorable factor for prognosis of AL patients except acute promyelocytic leukemia.
ATP Binding Cassette Transporter, Sub-Family G, Member 2 ; ATP-Binding Cassette Transporters ; genetics ; Acute Disease ; Adolescent ; Adult ; Aged ; Drug Resistance, Neoplasm ; Female ; Humans ; Leukemia ; drug therapy ; genetics ; Male ; Middle Aged ; Neoplasm Proteins ; genetics ; RNA, Messenger ; analysis

OBJECTIVETo filtrate breast cancer resistance protein (BCRP)-mediated resistant agents and to investigate clinical relationship between BCRP expression and drug resistance.

METHODSMTT assay was performed to filtrate BCRP-mediated resistant agents with BCRP expression cell model and to detect chemosensitivity of breast cancer tissue specimens to these agents. A high performance liquid chromatography (HPLC) assay was established, and was used to measure the relative dose of intracellular retention resistant agents. RT-PCR and immunohistochemistry (IHC) were employed to investigate the BCRP expression in breast cancer tissue specimens.

RESULTSMTT assay showed that the expression of BCRP increased with the increasing resistance of 5-fluorouracil (5-Fu) (P<0.05, n=3) in the cell model, while HPLC assay indicated that the intracellular retention dose of 5-Fu was significantly correlated with the expression of BCRP (r=-0.897, P<0.05, n=3). A total of 140 breast cancer tissue specimens were collected. BCRP-positive expression was detected in forty-seven specimens by both RT-PCR and IHC. As shown by MTT assay subsequently, the resistance index (RI) of 47 BCRP-positive breast cancer tissue specimens to 5-Fu was 7-12 times as high as that of adjacent normal tissue samples. BCRP expression was related to 5-Fu resistance (R2=0.8124, P<0.01).

CONCLUSIONResistance to 5-Fu can be mediated by BCRP. Clinical chemotherapy for breast cancer patients can be optimized based on BCRP-positive expression.

ATP Binding Cassette Transporter, Sub-Family G, Member 2 ; ATP-Binding Cassette Transporters ; metabolism ; Adult ; Antimetabolites, Antineoplastic ; pharmacology ; Chromatography, High Pressure Liquid ; Drug Resistance, Neoplasm ; Female ; Fluorouracil ; pharmacology ; Humans ; Immunohistochemistry ; Middle Aged ; Neoplasm Proteins ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction

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

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 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