Breast Neoplasms ; metabolism ; Female ; Humans ; Multidrug Resistance-Associated Proteins ; genetics ; metabolism ; Receptor, Epidermal Growth Factor ; metabolism ; Receptors, Progesterone ; metabolism

OBJECTIVETo investigate the effect of multidrug resistance-associated protein 4 (MRP4) expression on the radiosensitivity of colorectal carcinoma cell lines in vitro.

METHODSThe vector of shRNA for RNA interference was constructed and then transfected into HCT116 cell line to steadily down-regulate the expression of MRP4. HCT116 cells were divided into 3 groups including the CON group(non-transfected), NC group (negative control virus was added), and KD group (RNAi target was added for transfection). To test the effectiveness of RNA interference, real-time polymerase chain reaction and Western blot were used to measure the expression pattern of MRP4 at both mRNA and protein levels, respectively. For the examination of the effect of RNA interference of MRP4 on the radiosensitivity, flow cytometry was used to calculate the rate of apoptotic cells 24 h after 4 Gy radiation. Proliferation of the cells was measured via MTT assay at different time points.

RESULTSShRNA plasmid was successfully constructed. Transfection of this constructed vector into HCT116 cell line caused steady silencing of MRP4 expression (HCT116-KD). MRP4 mRNA and protein expression were significantly down-regulated following RNA interference(P<0.05). Twenty-four hours after radiation, the apoptosis rate of KD cell line was (71.7±0.8)%, significantly higher than that in the CON group [(56.1±0.9)%] and NC group[(59.8±0.8)%](P<0.05). Fourty-eight hours and 72 hours after radiation, the proliferation was significantly inhibited in KD cells compared to the control groups(P<0.05).

CONCLUSIONSExpression of MRP4 is closely related to radio-tolerance of colorectal carcinoma. Down-regulation of MRP4 expression by RNA interference enhances radiosensitivity of colorectal carcinoma cell lines in vitro. MRP4 may be an effective molecular marker for predicting the radiosensitivity of colorectal carcinoma.

Colorectal Neoplasms ; genetics ; metabolism ; Down-Regulation ; HCT116 Cells ; Humans ; Multidrug Resistance-Associated Proteins ; genetics ; RNA Interference ; Radiation Tolerance ; genetics

OBJECTIVETo study the reverse effect and its mechanism of tetrandrine (Tet) on human breast cancer cells resistant to tamoxifen (MCF-7/TAM).

METHODSThe drug toxicity and the reverse effect of Tet on MCF-7/TAM cells were detected by MTT assay. The effects of multidrug resistance protein 1 (MRP1) gene of Tet on MCF-7iTAM cells were detected by real-time fluorescence quantitative PCR. The changes of MRP1 protein on MCF-7JTAM cells were detected by Western blot.

RESULTSTet had a significant reversal of drug resistance on MCF-7/TAM cells. The non-cytotoxic dose (0. 625 microg/mL) reversed the resistance by 2.0 folds. MRP1 was reduced at gene (P <0.05) and protein levels when Tet effected on MCF-7ITAM cells.

CONCLUSIONTet could reverse the drug resistance of MCF-7/TAM cells, and the reverse mechanism may be related to down-regulating MRP1 expression.

Benzylisoquinolines ; pharmacology ; Drug Resistance, Neoplasm ; drug effects ; genetics ; Female ; Humans ; MCF-7 Cells ; drug effects ; Multidrug Resistance-Associated Proteins ; metabolism ; Tamoxifen ; pharmacology

OBJECTIVETo explore the relationship between multidrug resistance (Mdr) and malignancy. To observe whether P-glycoprotein (P-gp) overexpression had the same bioactivity as osteogenic stem cell turning into more mature cell or more complex phenotype when parent cell line turned to Mdr phenotype.

METHODSSix cell sublines of Mdr phenotype with different expression degree were analyzed. Stathmin generally identified in malignancy cell and stem cell, was a microtubule associated protein and the signal of differentiation in osteogenic stem cell. RT-PCR and hybridization in situ were used to analyze the relationship between Mdr1 mRNA and expression of Stathmin mRNA and VEGF mRNA.

RESULTSMorphological and functional analysis of Mdr phenotype showed the P-gp-positive cell lines were more differentiated than the parent cells in terms of enhanced activity of cellular alkaline phosphatase. These subclones all displayed a decrease in potential malignancy such as tumor growth rate and metastatic ability. A significant negative correlation could be identified between Mdr1 mRNA and expression of VEGF and Stathmin mRNA.

CONCLUSIONExpression of Mdr1/P170 indicated osteosarcoma cells differentiated towards more mature state, which will develop the new research field of Mdr and supply the new research method of the function of P- gp.

ATP-Binding Cassette, Sub-Family B, Member 1 ; genetics ; metabolism ; Cell Differentiation ; Cell Line, Tumor ; Drug Resistance, Multiple ; Drug Resistance, Neoplasm ; Gene Expression ; Humans ; Multidrug Resistance-Associated Proteins ; genetics ; metabolism ; Osteosarcoma ; genetics ; metabolism ; physiopathology ; Vascular Endothelial Growth Factor A ; genetics ; metabolism

OBJECTIVE: This study aimed to explore the relationship among expression of Survivin and MRP and drug resistance in NPC. METHOD: Expression of Survivin were detected by immunohistochemistry method in 45 cases of NPC and 24 cases of normal mucous membrane of nasopharynx (NMMN). The relationship between expression of Survivin and pathological factors in NPC were analysized. Expression of Survivin and MRP were detected in 31 patients of NPC with paclitaxel resistance and 20 patients of NPC without paclitaxel resistance. The relation- ship among the expression of Survivin or MRP and paclitaxel resistance in NPC were analysized. The paclitaxel resistance cell line, 5-8F-PTX(+); was established by a step-increased method. The expression of Survivin and MRP were detected by western blot in 5-8F-PTX(+) and 5-8F. RESULT: The positive were 71. 1% (32/45) in NPC and 8.33% (2/24) in NMMN. And there were significantly differences between them (P < .05). There were relationship among expression of Survivin and differentiation degree, lymph node metastasis, distant metastasis, and clinic stages of NPC. The positive were 75.9% (31/39) in moderately differentiated NPC and 16.7% (1/6) in lowly differentiated NPC, respectively. There were significantly differences between them (P < 0.05). The positive of Survivin were 83.9% (26/31) in NPC patients with paclitaxel resistance and 45.0% (9/20) in NPC patients without Paclitaxel resistance, respectively. There were significantly differences between them (P < 0.05). The positive of MRP were 87.1% (27/31) in NPC patients with paclitaxel resistance and 40.0% (8/20) in NPC patients without paclitaxel resistance, respectively. There were significantly differences between them (P < 0.05). There were positive correlation between the expression of Survivin and MRP in NPC patients with Paclitaxel resistance. The expression of Survivin and MRP were higher in 5-8F-PTX(+) than in 5-8F. The IC50 of paclitaxel, cDDP, 5-FU and Vincristine were significantly higher in 5-8F-PTX(+) than in 5-8F. CONCLUSION There were relationship among the expression of Survivin and difference, metastasis and TNM stages of NPC. Survivin may serves as a molecular marker for development and progress in NPC. There were relationship among the high expression of Survivin and MRP and increasing of drug resistance in NPC.
Antineoplastic Agents ; pharmacology ; Carcinoma ; Cisplatin ; Drug Resistance, Neoplasm ; Fluorouracil ; Humans ; Immunohistochemistry ; Inhibitor of Apoptosis Proteins ; genetics ; metabolism ; Lymphatic Metastasis ; Multidrug Resistance-Associated Proteins ; genetics ; metabolism ; Nasopharyngeal Carcinoma ; Nasopharyngeal Neoplasms ; genetics ; metabolism ; Nasopharynx ; metabolism ; Paclitaxel ; pharmacology ; Survivin ; Vincristine

OBJECTIVETo investigate the correlation between miR-221 and epithelial-mesenchymal transition (EMT) in drug-resistant glioma cells.

METHODSThe expression levels of miR-221, PTEN, p-Akt, E-cadherin, vimentin, and MRP1 were quantitatively analyzed in Z1 cells (primary drug-resistant cells), Z2 cells (drug-sensitive cells) and Z2-BCNU cells (drug-resistant cells) using fluorescent real-time PCR and Western blotting.

RESULTSThe expression levels of PTEN were significantly increased in Z2 cells compared with Z1 and Z2-BCNU cells which overexpressed miR-221 and vimentin. The expression levels of vimentin, p-Akt and MRP1 were significantly decreased in Z2 cells overexpressing E-cadherin.

CONCLUSIONMiR-221 regulates the expression of EMT-related genes through down-regulation of PTEN and activation of PI3-K/Akt signaling.

Cadherins ; metabolism ; Cell Line, Tumor ; Drug Resistance, Neoplasm ; Epithelial-Mesenchymal Transition ; Gene Expression Regulation, Neoplastic ; Humans ; MicroRNAs ; genetics ; metabolism ; Multidrug Resistance-Associated Proteins ; metabolism ; PTEN Phosphohydrolase ; metabolism ; Proto-Oncogene Proteins c-akt ; metabolism ; Signal Transduction ; Vimentin ; metabolism

OBJECTIVETo investigate the role of multidrug resistance-associated protein 2 (MRP2) in the hepatic cell membrane of rats.

METHODSThirty healthy Wistar rats were divided randomly into six groups based on time of administration (2 w, 4 w, 6 w) of 20 mg/kg of sodium arsenite, and their corresponding control groups. Animals were administered every other day. Arsenic content in blood and bile were detected by atomic absorption spectroscopy (AAS), and the expression of MRP2 in the membrane of hepatocyte by Western blotting was determined.

RESULTSTotal arsenic levels (including organic arsenic and inorganic arsenic) in blood and bile were significantly higher than control groups (P < 0.05) at all three different time points, especially in 2 w and 4 w group (16.8 and 13.8 fold greater than that in control). The expression of MRP2 increased 36.61%, 32.36%, 12.73% more respectively in 2 w, 4 w, 6 w groups than those in control groups (P < 0.05). The expression of MRP2 was correlated with total arsenic content in bile (r = 0.713, P < 0.05).

CONCLUSIONSBile is one of the major routes for the excretion of arsenite and its metabolites, and the overexpression of MRP2 may play an important role in the bile excretion of them at early stage.

Animals ; Arsenic Poisoning ; metabolism ; Arsenites ; pharmacology ; Bile ; metabolism ; Hepatocytes ; drug effects ; metabolism ; Liver ; metabolism ; Membrane Transport Proteins ; genetics ; metabolism ; Multidrug Resistance-Associated Proteins ; genetics ; metabolism ; Random Allocation ; Rats ; Rats, Wistar

Amino Acid Substitution ; Drug Resistance, Multiple, Bacterial ; physiology ; Escherichia coli ; physiology ; Escherichia coli Proteins ; genetics ; metabolism ; Membrane Potentials ; physiology ; Models, Biological ; Multidrug Resistance-Associated Proteins ; genetics ; metabolism ; Mutation, Missense

OBJECTIVESTo investigate the reversal effect of gene MDR1 and MRP with combinational antisense phosphorothioate oligonucleotide on Drug-resistant human hepatocellular carcinoma cells SMMC-7721/ADM.

METHODSSMMC-7721/ADM was transfected with synthetic antisense phosphorothioate oligonucleotides complementary to gene MDR1 and MRP mediated by Lipofectamine. Drug sensitivity was measured by MTT assay, Fluorescence intensity of cells was determined by flow cytometric analysis, RH123 and DNR retention was assayed by confocal scanning laser microscopy.

RESULTSASODN of MDR1+MRP increased the sensitivity of SMMC-7721/ADM to chemotherapeutic drug more significantly than that any of MDR1 and MRP did separately. But they did not enhance the inhibition expression of protein of p190 or p170.

CONCLUSIONDrug-resistance could be reversed significantly when antisense phosphorothioate oligonucleotide of MDR1+MRP were transfected into drug-resistant human hepatocellular carcinoma cells SMMC-7721/ADM together.

Carcinoma, Hepatocellular ; drug therapy ; genetics ; Cell Line, Tumor ; Daunorubicin ; metabolism ; pharmacology ; Doxorubicin ; pharmacology ; Drug Resistance, Neoplasm ; Genes, MDR ; Humans ; Liver Neoplasms ; drug therapy ; genetics ; Multidrug Resistance-Associated Proteins ; genetics ; Oligonucleotides, Antisense ; pharmacology ; Rhodamine 123 ; metabolism

Our previous study demonstrated that BM-cyclin 1, a traditional anti-mycoplasma drug, could effectively reverse the multidrug resistance (MDR) of C-A120 cells. The present study aims to explore the reversal effect of BM-cyclin 1 on MDR and its mechanisms in BALB/C nude mice bearing C-A120 cells. Immunoblotting analysis and reverse transcription-polymerase chain reaction (RT-PCR) were used to study the change in multidrug resistance-associated protein 2 (MRP2) induced by BM-cyclin 1. We found that the expression levels of MRP2 protein and mRNA in C-A120 cells treated with BM-cyclin 1 were reduced significantly. Chemical colorimetry revealed no significant change in the level of glutathione (GSH). In the xenograft model, the inhibitory rate of C-A120 cells growth in BM-cyclin 1 plus adriamycin (ADM) group was 52%, which was significantly higher than in control group (P<0.01). The immunoblotting and RT-PCR results conclusively demonstrated that BM-cycin 1 could significantly reduce the expression of MRP2 in transplanted tumor. In conclusion, BM-cyclin 1 could effectively reverse the MDR of C-A120 cells in vivo by suppressing the expression of MRP2.
Animals ; Antiprotozoal Agents ; pharmacology ; Cell Line, Tumor ; Diterpenes ; pharmacology ; Down-Regulation ; Doxorubicin ; pharmacology ; Drug Resistance, Multiple ; drug effects ; Humans ; Mice ; Mice, Nude ; Minocycline ; pharmacology ; Multidrug Resistance-Associated Proteins ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Xenograft Model Antitumor Assays