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Sample records for multidrug resistance p-glycoprotein

  1. Bacterial multidrug resistance mediated by a homologue of the human multidrug transporter P-glycoprotein

    NARCIS (Netherlands)

    Konings, WN; Poelarends, GJ

    2002-01-01

    Most ATP-binding cassette (ABC) multidrug transporters known to date are of eukaryotic origin, such as the P-glycoproteins (Pgps) and multidrug resistance-associated proteins (MRPs). Only one well-characterized ABC multidrug transporter, LmrA, is of bacterial origin. On the basis of its structural a

  2. Differential expression of sphingolipids in P-glycoprotein or multidrug resistance-related protein 1 expressing human neuroblastoma cell lines

    NARCIS (Netherlands)

    Dijkhuis, AJ; Douwes, J; Kamps, W; Sietsma, H; Kok, JW

    2003-01-01

    The sphingolipid composition and multidrug resistance status of three human neuroblastoma cell lines were established. SK-N-FI cells displayed high expression and functional (efflux) activity of P-glycoprotein, while multidrug resistance-related protein 1 was relatively abundant and most active in S

  3. Age-related changes of the multidrug resistance P-glycoprotein function in normal human peripheral blood T lymphocytes

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    C.G. Machado

    2003-12-01

    Full Text Available The multidrug resistance P-glycoprotein is a transmembrane efflux pump expressed by lymphocytes and is involved in their cytolytic activity. In the present study, we investigated the age-related changes of P-glycoprotein function in normal peripheral blood lymphocytes. Blood samples from 90 normal volunteers (age range, 0 to 86 years were analyzed. P-glycoprotein function was assessed by the flow cytometric rhodamine 123 assay. P-glycoprotein function was highest in cord blood and progressively declined with age in peripheral blood T CD4+ and CD8+ cells. In contrast, P-glycoprotein function did not vary with age in CD19+ B or CD16+CD56+ natural killer cells. These data suggest that the decline in P-glycoprotein function in T CD4+ and CD8+ lymphocytes as a function of age may contribute to the decrease in T cell cytolytic activity with aging.

  4. Discovery of novel P-glycoprotein-mediated multidrug resistance inhibitors bearing triazole core via click chemistry.

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    Liu, Baomin; Qiu, Qianqian; Zhao, Tianxiao; Jiao, Lei; Hou, Jianyu; Li, Yunman; Qian, Hai; Huang, Wenlong

    2014-08-01

    A novel series of P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) inhibitors bearing a triazol-phenethyl-tetrahydroisoquinoline scaffold were designed and synthesized via click chemistry. Most of the synthesized compounds showed higher reversal activity than verapamil (VRP). Among them, the most potent compound 5 showed a comparable activity with the known potent P-gp inhibitor WK-X-34 with lower cytotoxicity (IC50s > 100 μm). Compared with VRP, compound 5 exhibited more potency in increasing drug accumulation in K562/A02 MDR cells. Moreover, compound 5 persisted longer chemo-sensitizing effect (>24 h) than VRP (<6 h) with reversibility. Given the low intrinsic cytotoxicity and the potent reversal activity, compound 5 may represent a promising candidate for developing P-gp-mediated MDR inhibitor.

  5. Effect of multidrug resistance 1/P-glycoprotein on the hypoxia-induced multidrug resistance of human laryngeal cancer cells.

    Science.gov (United States)

    Li, Dawei; Zhou, Liang; Huang, Jiameng; Xiao, Xiyan

    2016-08-01

    In a previous study, it was demonstrated that hypoxia upregulated the multidrug resistance (MDR) of laryngeal cancer cells to chemotherapeutic drugs, with multidrug resistance 1 (MDR1)/P-glycoprotein (P-gp) expression also being upregulated. The present study aimed to investigate the role and mechanism of MDR1/P-gp on hypoxia-induced MDR in human laryngeal carcinoma cells. The sensitivity of laryngeal cancer cells to multiple drugs and cisplatin-induced apoptosis was determined by CCK-8 assay and Annexin-V/propidium iodide staining analysis, respectively. The accumulation of rhodamine 123 (Rh123) in the cells served as an estimate of drug accumulation and was evaluated by flow cytometry (FCM). MDR1/P-gp expression was inhibited using interference RNA, and the expression of the MDR1 gene was analyzed using reverse transcription-quantitative polymerase chain reaction and western blotting. As a result, the sensitivity to multiple chemotherapeutic agents and the apoptosis rate of the hypoxic laryngeal carcinoma cells increased following a decrease in MDR1/P-gp expression (PP-gp markedly increased intracellular Rh123 accumulation (PP-gp serves an important role in regulating hypoxia-induced MDR in human laryngeal carcinoma cells through a decrease in intracellular drug accumulation.

  6. Laurus nobilis L. Seed Extract Reveals Collateral Sensitivity in Multidrug-Resistant P-Glycoprotein-Expressing Tumor Cells.

    Science.gov (United States)

    Saab, Antoine M; Guerrini, Alessandra; Zeino, Maen; Wiench, Benjamin; Rossi, Damiano; Gambari, Roberto; Sacchetti, Gianni; Greten, Henry Johannes; Efferth, Thomas

    2015-01-01

    The frequent failure of standard cancer chemotherapy requires the development of novel drugs capable of killing otherwise drug-resistant tumors. Here, we have investigated a chloroform extract of Laurus nobilis seeds. Fatty acids and 23 constituents of the volatile fraction were identified by gas chromotography/flame ionization detection (GC/FID) and gas chromatography/mass spectrometry (GC/MS), in good agreement with (1)H NMR (nuclear magnetic resonance) spectrum. Multidrug-resistant P-glycoprotein-expressing CEM/ADR5000 leukemia cells were hypersensitive (collaterally sensitive) toward this extract compared to drug-sensitive CCRF-CEM cells, whereas CEM/ADR5000 cells were 2586-fold resistant to doxorubicin as control drug. Collateral sensitivity was verified by measurement of apoptotic cells by flow cytometry. The log10IC50 values of 3 compounds in the extract (limonene, eucalyptol, oleic acid) did not correlate with mRNA expression of the P-glycoprotein-coding ABCB1/MDR1 gene and accumulation of the P-glycoprotein substrate rhodamine in the NCI panel of tumor cell lines. A microarray-based profile of 20 genes predicted resistance to doxorubicin and 7 other anticancer drugs involved in the multidrug resistance phenotype but not to limonene, eucalyptol and oleic acid. In conclusion, our results show that Laurus nobilis seed extract is suitable to kill multidrug-resistant P-glycoprotein expressing tumor cells.

  7. Reversion of P-Glycoprotein-Mediated Multidrug Resistance in Human Leukemic Cell Line by Diallyl Trisulfide

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    Qing Xia

    2012-01-01

    Full Text Available Multidrug resistance (MDR is the major obstacle in chemotherapy, which involves multiple signaling pathways. Diallyl trisulfide (DATS is the main sulfuric compound in garlic. In the present study, we aimed to explore whether DATS could overcome P-glycoprotein-(P-gp-mediated MDR in K562/A02 cells, and to investigate whether NF-κB suppression is involved in DATS-induced reversal of MDR. MTT assay revealed that cotreatment with DATS increased the response of K562/A02 cells to adriamycin (the resistance reversal fold was 3.79 without toxic side effects. DATS could enhance the intracellular concentration of adriamycin by inhibiting the function and expression of P-gp, as shown by flow cytometry, RT-PCR, and western blot. In addition, DATS resulted in more K562/A02 cell apoptosis, accompanied by increased expression of caspase-3. The expression of NF-κB/p65 (downregulation was significantly linked to the drug-resistance mechanism of DATS, whereas the expression of IκBα was not affected by DATS. Our findings demonstrated that DATS can serve as a novel, nontoxic modulator of MDR, and can reverse the MDR of K562/A02 cells in vitro by increasing intracellular adriamycin concentration and inducing apoptosis. More importantly, we proved for the first time that the suppression of NF-κB possibly involves the molecular mechanism in the course of reversion by DATS.

  8. Modulation of P-glycoprotein function and multidrug resistance in cancer cells by Thai plant extracts.

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    Takano, M; Kakizoe, S; Kawami, M; Nagai, J; Patanasethnont, D; Sripanidkulchai, B; Yumoto, R

    2014-11-01

    The effects of ethanol extracts from Thai plants belonging to the families of Annonaceae, Rutaceae, and Zingiberaceae on P-glycoprotein (P-gp) function and multidrug resistance were examined in paclitaxel-resistant HepG2 (PR-HepG2) cells. All the extracts tested, significantly increased the accumulation of [3H]paclitaxel, a P-gp substrate, in the cells. Among nine extracts, Z01 and Z02, extracts from Curcuma comosa and Kaempferia marginata (Zingiberaceae family), respectively, potently increased the accumulation. In addition, Z01 and Z02 increased the accumulation of other P-gp substrates, rhodamine 123 and doxorubicin, in PR-HepG2 cells in a concentration-dependent manner. Increased accumulation of rhodamine 123 and doxorubicin by Z01 and Z02 was also confirmed by confocal laser scanning microscopy. The effect of Z01 and Z02 pretreatment on the expression of MDR1 mRNA was also examined. The expression of MDR1 mRNA was not affected by the treatment of PR-HepG2 cells with these extracts for 48 hours. Cytotoxicity of paclitaxel was examined by XTT and protein assays in the absence and presence of Z02. Z02 potentiated the cytotoxicity of paclitaxel in PR-HepG2 cells. These results suggest that Curcuma comosa and Kaempferia marginata belonging to Zingiberaceae are useful sources to search for new P-gp modulator(s) that can be used to overcome multidrug resistance of cancer cells.

  9. Extracellular galectin-3 programs multidrug resistance through Na+/K+-ATPase and P-glycoprotein signaling.

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    Harazono, Yosuke; Kho, Dhong Hyo; Balan, Vitaly; Nakajima, Kosei; Hogan, Victor; Raz, Avraham

    2015-08-14

    Galectin-3 (Gal-3, LGALS3) is a pleotropic versatile, 29-35 kDa chimeric gene product, and involved in diverse physiological and pathological processes, including cell growth, homeostasis, apoptosis, pre-mRNA splicing, cell-cell and cell-matrix adhesion, cellular polarity, motility, adhesion, activation, differentiation, transformation, signaling, regulation of innate/adaptive immunity, and angiogenesis. In multiple diseases, it was found that the level of circulating Gal-3 is markedly elevated, suggesting that Gal-3-dependent function is mediated by specific interaction with yet an unknown ubiquitous cell-surface protein. Recently, we showed that Gal-3 attenuated drug-induced apoptosis, which is one of the mechanisms underlying multidrug resistance (MDR). Here, we document that MDR could be mediated by Gal-3 interaction with the house-keeping gene product e.g., Na+/K+-ATPase, and P-glycoprotein (P-gp). Gal-3 interacts with Na+/K+-ATPase and induces the phosphorylation of P-gp. We also find that Gal-3 binds P-gp and enhances its ATPase activity. Furthermore Gal-3 antagonist suppresses this interaction and results in a decrease of the phosphorylation and the ATPase activity of P-gp, leading to an increased sensitivity to doxorubicin-mediated cell death. Taken together, these findings may explain the reported roles of Gal-3 in diverse diseases and suggest that a combined therapy of inhibitors of Na+/K+-ATPase and Gal-3, and a disease specific drug(s) might be superior to a single therapeutic modality.

  10. Essential features of the P-glycoprotein pharmacophore as defined by a series of reserpine analogs that modulate multidrug resistance.

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    Pearce, H L; Safa, A R; Bach, N J; Winter, M A; Cirtain, M C; Beck, W T

    1989-07-01

    We have shown previously that reserpine is an effective "modulator" of P-glycoprotein-associated multidrug resistance (MDR). In addition to enhancing drug cytotoxicity in our multidrug-resistant human leukemia cell line, CEM/VLB100, reserpine strongly competes with a photoactivatible analog of vinblastine, N-(p-azido-3-[125I]iodosalicyl)-N'-(beta-aminoethyl)vindesine, for binding to P-glycoprotein. We also demonstrated previously that there are three substructural domains present in many compounds that modulate P-glycoprotein-associated MDR: a basic nitrogen atom and two planar aromatic rings. In the present study, we wished to test more rigorously the hypothesis that not only are these domains necessary for modulators of MDR but also they must exist in an appropriate conformation. Reserpine is a modulator of MDR in which these domains are present in a well-defined conformation. Accordingly, we prepared eight compounds that vary the spatial orientation of these domains, using either naturally occurring reserpine or yohimbine as chemical templates. When tested for their ability to enhance the cytotoxic activity of natural product antitumor drugs in CEM/VLB100 cells, five compounds that retained the pendant benzoyl function in an appropriate spatial orientation all modulated MDR. By contrast, compounds lacking this moiety failed to do so. These active modulators competed strongly with the 125I-labeled vinblastine analog for binding to P-glycoprotein in plasma membrane vesicles prepared from these cells. Conformational analysis using molecular mechanics revealed the structural similarities of the active modulators. Our results support the hypothesis that the relative disposition of aromatic rings and basic nitrogen atom is important for modulators of P-glycoprotein-associated MDR, and they suggest a ligand-receptor relationship for these agents. These results also provide direction for the definition of an MDR "pharmacophore."

  11. The expression and significance of P-glycoprotein, lung resistance protein and multidrug resistance-associated protein in gastric cancer

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    Li Yan

    2009-11-01

    Full Text Available Abstract Background To detect the expression of multidrug resistance molecules P-glycoprotein (P-gp, Lung resistnce protein (LRP and Multidrug resistance-associated protein (MRP and analyze the relationship between them and the clinico-pathological features. Methods The expressions of P-gp, LRP and MRP in formalin-fixed paraffin-embedded tissue sections from 59 gastric cancer patients were determined by a labbelled Streptavidin-Peroxidase (SP immunohistochemical technique, and the results were analyzed in correlation with clinicopathological data. None of these patients received chemotherapy prior to surgery. Results The positive rates of P-gp, LRP, MRP were 86.4%, 84.7% and 27.1%, respectively. The difference between the positive rate of P-gp and MRP was significant statistically, as well as the difference between the expression of MRP and LRP. No significant difference was observed between P-gp and LRP, but the positively correlation between the expression of P-gp and LRP had been found. No significant correlation between the expression of P-gp, LRP, MRP and the grade of differentiation were observed. The expression of P-gp was correlated with clinical stages positively (r = 0.742, but the difference with the expression of P-gp in different stages was not significant. Conclusion The expressions of P-gp, LRP and MRP in patients with gastric cancer without prior chemotherapy are high, indicating that innate drug resistance may exist in gastric cancer.

  12. Expression of P-glycoprotein and multidrug resistance associated protein in Ehrlich ascites tumor cells after fractionated irradiation

    DEFF Research Database (Denmark)

    Nielsen, D; Maare, C; Eriksen, J;

    2001-01-01

    PURPOSE: To characterize irradiated murine tumor cells with respect to drug resistance, drug kinetics, and ATPase activity, and to evaluate the possible role of P-glycoprotein (PGP) and murine multidrug resistance associated protein (Mrp1) in the drug-resistant phenotype of these cells. METHODS...... AND MATERIALS: Sensitive Ehrlich ascites tumor cells (EHR2) were in vitro exposed to fractionated irradiation (60 Gy). Western blot analysis was performed for determination of PGP and Mrp1, reverse transcriptase-polymerase chain reaction (RT-PCR) for determination of mdr1a + b mRNA, and semiquantitative RT......, the release of inorganic phosphate from ATP was quantified using a colorimetric method. RESULTS: Compared with EHR2, the irradiated cell line EHR2/irr showed increased expression of PGP (threefold), Mrp1 (eightfold), and Mrp1 mRNA (sixfold), and a slight reduction of mdr1b mRNA, whereas mdr1a was present...

  13. Down-regulation of the P-glycoprotein relevant for multidrug resistance by intracellular acidification through the crosstalk of MAPK signaling pathways.

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    Jin, Weina; Lu, Ying; Li, Qinghua; Wang, Jian; Zhang, Hongju; Chang, Guoqiang; Lin, Yani; Pang, Tianxiang

    2014-09-01

    In our previous study, we have found that the tumor multidrug resistance mediated by P-glycoprotein could be reversed by sustained intracellular acidification through down-regulating the multidrug resistance gene 1 mRNA and P-glycoprotein expression. However, the molecular events linking the intracellular acidification and the regulation of P-glycoprotein remain unclear. In the present study, the molecular pathways involved in the regulation of P-glycoprotein expression by the intracellular acidification were investigated. We found that the P-glycoprotein expression was down-regulated by the intracellular acidification through inhibition of p38 mitogen-activated protein kinase (MAPK) and the activation of c-Jun N-terminal kinase (JNK) in the resisitant K562/DOX cells. In the sensitive K562 and HL60 cell lines, the changes of the p38 MAPK expression after the acidification are not as obvious as that of K562/DOX cells, but the activation of extracellular signal-regulated kinase (ERK) is also observed, which indicates that the down-regulation of p38 MAPK by the intracellular acidification might be the resistant cell line specific. Blockade of ERK and JNK signaling by the inhibitors or RNA interference increased p38MAPK activities suggesting that cross-talk within MAPKs is also important for this response. Our study provides the first direct evidence that the reversal of P-glycoprotein-mediated multidrug resistance by intracellular acidification is mediated by the crosstalk of MAPK signaling pathways.

  14. Characterization of phosphine complexes of technetium(III) as transport substrates of the multidrug resistance P-glycoprotein and functional markers of P-glycoprotein at the blood-brain barrier.

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    Luker, G D; Rao, V V; Crankshaw, C L; Dahlheimer, J; Piwnica-Worms, D

    1997-11-18

    The multidrug resistance (MDR1) P-glycoprotein functions as a broad specificity efflux transporter of structurally diverse natural product and xenobiotic compounds. P-glycoprotein also is an important component of the functional blood-brain barrier. To enable further studies of function and modulation of MDR1 P-glycoprotein in vitro and in vivo, two novel phosphine technetium(III) complexes were designed and characterized: trans-[2,2'-(1, 2-ethanediyldiimino)bis(1, 5-methoxy-5-methyl-4-oxo-hexenyl)]bis[methylbis(3-methoxy-1- propyl)ph osphine]Tc(III) (Tc-Q58) and trans-[5,5'-(1,2-ethanediyl diimino)bis(2-ethoxy-2-methyl-3-oxo-4-pentenyl)]bis[dimethyl(3- methox y-1-propyl)phosphine)]Tc(III) (Tc-Q63). In human drug-sensitive KB 3-1 cells and multidrug-resistant KB 8-5 and 8-5-11 derivative cell lines, expressing nonimmunodetectable, low, and high levels of MDR1 P-glycoprotein, respectively, accumulation of Tc-Q58 and Tc-Q63 was inverse to expression of the transporter. Differences between drug-sensitive and multidrug-resistant cells, while detectable at picomolar concentrations of each radiopharmaceutical, were independent of tracer concentration. Ratios of tracer accumulation in KB 3-1 and 8-5 cells were 62.3 and 48.1 for Tc-Q58 and Tc-Q63, respectively. Cell contents of Tc-Q58 and Tc-Q63 were enhanced up to 60-fold in MDR cells by known modulators of MDR1 P-glycoprotein, while drugs not in the multidrug-resistant phenotype had no effect on their accumulation. In KB 8-5 cells, potency of modulators was GF120918 > cyclosporin A > verapamil. Accumulation of Tc-Q58 and Tc-Q63 in Sf9 insect cells infected with a recombinant baculovirus containing human MDR1 P-glycoprotein was reduced in a GF120918-reversible manner (EC50 phosphine-containing metal complexes. As shown with Tc-Q58, these Q complexes can be used to detect transport activity and modulation of MDR1 P-glycoprotein in vitro and to directly monitor the functional status of P-glycoprotein at the blood

  15. Characterisation of non-P-glycoprotein multidrug-resistant Ehrlich ascites tumour cells selected for resistance to mitoxantrone

    DEFF Research Database (Denmark)

    Nielsen, D; Eriksen, J; Maare, C;

    2000-01-01

    . The efflux of daunorubicin from preloaded EHR2/MITOX cells was significantly increased. EHR2/MITOX microsomes had a significant basal unstimulated ATPase activity. The apparent K(i) value for vanadate inhibition of the ATPase activity in EHR2/MITOX microsomes was not significantly different from the K......(i) value for P-glycoprotein-positive cells. However, whereas verapamil (50 microM) inhibited the ATPase activity of EHR2/MITOX microsomes, it stimulated the ATPase activity of microsomes derived from P-glycoprotein-positive cells. In conclusion, the resistance in EHR2/MITOX was multifactorial and appeared...

  16. Topology and Function of Human p-Glycoprotein in Multidrug Resistant Breast Cancer Cells

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    1999-08-01

    analysis and both drug transport and regulation of swelling-activated chloride currents were examined. To date our results are incomplete to draw...P-glycoprotein, topology, 15. NUMBER.OF PAGES Breast Cancer 32 swelling-activated chloride currents 16. PRICE CODE 17. SECURITY CLASSIFICATION 18...important proteins such as the cystic fibrosis transmembrane conductance regulator ( CFTR ) (1;2). This superfamily is generally characterized by a

  17. Effects of indole alkaloids on multidrug resistance and labeling of P-glycoprotein by a photoaffinity analog of vinblastine.

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    Beck, W T; Cirtain, M C; Glover, C J; Felsted, R L; Safa, A R

    1988-06-30

    Multidrug resistant cells are characterized by decreased drug accumulation and retention, thought to be mediated by a high molecular weight glycoprotein, P-glycoprotein (P-gp). Agents such as verapamil have been shown to increase anticancer drug cytotoxicity and increase the amount of drug accumulated and retained by such cells. We show here that in addition to verapamil, reserpine, chloroquine, quinine, quinacrine, yohimbine, vindoline, and catharanthine also enhance the cytotoxicity of vinblastine (VLB) in a multidrug resistant, human leukemic cell line, CEM/VLB1K, described here for the first time. These cells express P-gp as a doublet that is photoaffinity labeled by the analog of VLB, N(p-azido-[3-125I]salicyl)-N'-beta-aminoethylvindesine ([125I]NASV). Both reserpine and, to a lesser extent, verapamil, compete with [125I]NASV for binding to P-gp. We also found that chloroquine, quinacrine, vindoline, and catharanthine, each of which enhanced VLB cytotoxicity in CEM/VLB1K cells by 10- to 15-fold, similarly inhibited [125I]NASV labeling of P-gp. However, neither quinine nor yohimbine inhibited this labeling, and the inhibition produced by catharanthine and vindoline was the greatest or exclusively on the lower band of the P-gp doublet. Our results suggest a complex relationship between the ability of a compound to modulate MDR and its ability to compete for binding to P-gp.

  18. Natural lignans from Arctium lappa modulate P-glycoprotein efflux function in multidrug resistant cancer cells.

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    Su, Shan; Cheng, Xinlai; Wink, Michael

    2015-02-15

    Arctium lappa is a well-known traditional medicinal plant in China (TCM) and Europe that has been used for thousands of years to treat arthritis, baldness or cancer. The plant produces lignans as secondary metabolites which have a wide range of bioactivities. Yet, their ability to reverse multidrug resistance (MDR) in cancer cells has not been explored. In this study, we isolated six lignans from A. lappa seeds, namely arctigenin, matairesinol, arctiin, (iso)lappaol A, lappaol C, and lappaol F. The MDR reversal potential of the isolated lignans and the underlying mechanism of action were studied using two MDR cancer cell lines, CaCo2 and CEM/ADR 5000 which overexpress P-gp and other ABC transporters. In two-drug combinations of lignans with the cytotoxic doxorubicin, all lignans exhibited synergistic effects in CaCo2 cells and matairesinol, arctiin, lappaol C and lappaol F display synergistic activity in CEM/ADR 5000 cells. Additionally, in three-drug combinations of lignans with the saponin digitonin and doxorubicin MDR reversal activity was even stronger enhanced. The lignans can increase the retention of the P-gp substrate rhodamine 123 in CEM/ADR 5000 cells, indicating that lignans can inhibit the activity of P-gp. Our study provides a first insight into the potential chemosensitizing activity of a series of natural lignans, which might be candidates for developing novel adjuvant anticancer agents.

  19. HIF-1α inhibition reverses multidrug resistance in colon cancer cells via downregulation of MDR1/P-glycoprotein.

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    Jianfang Chen

    Full Text Available BACKGROUND: Multidrug resistance (MDR is one of the major reasons chemotherapy-based treatments fail. Hypoxia is generally associated with tumor chemoresistance. However, the correlation between the heterodimeric hypoxia-inducible factor-1 (HIF-1 and the multidrug resistance (MDR1 gene/transporter P-glycoprotein (P-gp remains unclear. This study aims to explore the molecular mechanisms of reversing colon cancer MDR by focusing on the target gene HIF-1α. METHODS: A chemotherapeutic sensitivity assay was used to observe the efficiency of MDR reversal in LoVo multicellular spheroids (MCS. The apoptotic level induced by different drugs was examined by flow cytometry (FCM. Binding of HIF-1α to the MDR1 gene promoter was evaluated by Chromatin immunoprecipitation (ChIP. The relationship between HIF-1α/P-gp expression and sensitivity to chemotherapy was analyzed. RESULTS: The sensitivity of LoVo MCS to all four chemotherapy drugs was decreased to varying degrees under hypoxic conditions. After silencing the HIF-1α gene, the sensitivities of LoVo MCS to all four chemotherapy drugs were restored. The apoptotic levels that all the drugs induced were all decreased to various extents in the hypoxic group. After silencing HIF-1α, the apoptosis level induced by all four chemotherapy drugs increased. The expression of HIF-1α and P-gp was significantly enhanced in LoVo MCS after treatment with hypoxia. Inhibiting HIF-1α significantly decreased the expression of MDR1/P-gp mRNA or protein in both the LoVo monolayers and LoVo MCS. The ChIP assay showed that HIF-1α was bound to the MDR1 gene promoter. Advanced colon carcinoma patients with expression of both HIF-1α and P-gp were more resistant to chemotherapy than that with non expression. CONCLUSIONS: HIF-1α inhibition reverses multidrug resistance in colon cancer cells via downregulation of MDR1/P-gp. The expression of HIF-1α and MDR1/P-gp can be used as a predictive marker for chemotherapy resistance

  20. Design, synthesis and evaluation of novel triazole core based P-glycoprotein-mediated multidrug resistance reversal agents.

    Science.gov (United States)

    Jiao, Lei; Qiu, Qianqian; Liu, Baomin; Zhao, Tianxiao; Huang, Wenlong; Qian, Hai

    2014-12-15

    A novel series of triazol-N-ethyl-tetrahydroisoquinoline based compounds were designed and synthesized via click chemistry. Most of the synthesized compounds showed P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) reversal activities. Among them, compound 7 with little cytotoxicity towards GES-1 cells (IC50 >80μM) and K562/A02 cells (IC50 >80μM) exhibited more potency than verapamil (VRP) on increasing anticancer drug accumulation in K562/A02 cells. Moreover, compound 7 could significantly reverse MDR in a dose-dependent manner and also persist longer chemo-sensitizing effect than VRP with reversibility. Further mechanism studies revealed that compound 7 in reversing MDR revealed that it could remarkably increase the intracellular accumulation of both rhodamine-123 (Rh123) and adriamycin (ADM) in K562/A02 cells as well as inhibit their efflux from the cells. These results suggested that compound 7 showed more potency than the classical P-gp inhibitor VRP under the same conditions, which may be a promising P-gp-mediated MDR modulator for further development.

  1. Design, synthesis and biological evaluation of LBM-A5 derivatives as potent P-glycoprotein-mediated multidrug resistance inhibitors.

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    Wu, Yuxiang; Pan, Miaobo; Dai, Yuxuan; Liu, Baomin; Cui, Jian; Shi, Wei; Qiu, Qianqian; Huang, Wenlong; Qian, Hai

    2016-05-15

    A novel series of P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) inhibitors with triazol-N-phenethyl-tetrahydroisoquinoline or triazol-N-ethyl-tetrahydroisoquinoline scaffold were designed and synthesized via click chemistry. Most of the synthesized compounds showed higher reversal activity than verapamil (VRP). Among them, the most potent compound 4 showed a comparable activity with the known potent P-gp inhibitor WK-X-34 with lower cytotoxicity toward K562 cells (IC50>100μM). Compared with VRP, compound 4 exhibited more potency in increasing drug accumulation in K562/A02 MDR cells. Moreover, compound 4 could significantly reverse MDR in a dose-dependent manner and also persist longer chemo-sensitizing effect than VRP with reversibility. Further mechanism studies revealed that compound 4 could remarkably increase the intracellular accumulation of Adriamycin (ADM) in K562/A02 cells as well as inhibit rhodamine-123 (Rh123) efflux from the cells. These results suggested that compound 4 may represent a promising candidate for developing P-gp-mediated MDR inhibitors.

  2. Turning the gun on cancer: Utilizing lysosomal P-glycoprotein as a new strategy to overcome multi-drug resistance.

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    Seebacher, Nicole; Lane, Darius J R; Richardson, Des R; Jansson, Patric J

    2016-07-01

    Oxidative stress plays a role in the development of drug resistance in cancer cells. Cancer cells must constantly and rapidly adapt to changes in the tumor microenvironment, due to alterations in the availability of nutrients, such as glucose, oxygen and key transition metals (e.g., iron and copper). This nutrient flux is typically a consequence of rapid growth, poor vascularization and necrosis. It has been demonstrated that stress factors, such as hypoxia and glucose deprivation up-regulate master transcription factors, namely hypoxia inducible factor-1α (HIF-1α), which transcriptionally regulate the multi-drug resistance (MDR), transmembrane drug efflux transporter, P-glycoprotein (Pgp). Interestingly, in addition to the established role of plasma membrane Pgp in MDR, a new paradigm of intracellular resistance has emerged that is premised on the ability of lysosomal Pgp to transport cytotoxic agents into this organelle. This mechanism is enabled by the topological inversion of Pgp via endocytosis resulting in the transporter actively pumping agents into the lysosome. In this way, classical Pgp substrates, such as doxorubicin (DOX), can be actively transported into this organelle. Within the lysosome, DOX becomes protonated upon acidification of the lysosomal lumen, causing its accumulation. This mechanism efficiently traps DOX, preventing its cytotoxic interaction with nuclear DNA. This review discusses these effects and highlights a novel mechanism by which redox-active and protonatable Pgp substrates can utilize lysosomal Pgp to gain access to this compartment, resulting in catastrophic lysosomal membrane permeabilization and cell death. Hence, a key MDR mechanism that utilizes Pgp (the "gun") to sequester protonatable drug substrates safely within lysosomes can be "turned on" MDR cancer cells to destroy them from within.

  3. A novel curcumin derivative which inhibits P-glycoprotein, arrests cell cycle and induces apoptosis in multidrug resistance cells.

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    Lopes-Rodrigues, Vanessa; Oliveira, Ana; Correia-da-Silva, Marta; Pinto, Madalena; Lima, Raquel T; Sousa, Emília; Vasconcelos, M Helena

    2017-01-15

    Cancer multidrug resistance (MDR) is a major limitation to the success of cancer treatment and is highly associated with the overexpression of drug efflux pumps such as P-glycoprotein (P-gp). In order to achieve more effective chemotherapeutic treatments, it is important to develop P-gp inhibitors to block/decrease its activity. Curcumin (1) is a secondary metabolite isolated from the turmeric of Curcuma longa L.. Diverse biological activities have been identified for this compound, particularly, MDR modulation in various cancer cell models. However, curcumin (1) has low chemical stability, which severely limits its application. In order to improve stability and P-gp inhibitory effect, two potential more stable curcumin derivatives were synthesized as building blocks, followed by several curcumin derivatives. These compounds were then analyzed in terms of antitumor and anti-P-gp activity, in two MDR and sensitive tumor lines (from chronic myeloid leukemia and non-small cell lung cancer). We identified from a series of curcumin derivatives a novel curcumin derivative (1,7-bis(3-methoxy-4-(prop-2-yn-1-yloxy)phenyl)hepta-1,6-diene-3,5-dione, 10) with more potent antitumor and anti-P-gp activity than curcumin (1). This compound (10) was shown to promote cell cycle arrest (at the G2/M phase) and induce apoptosis in the MDR chronic myeloid leukemia cell line. Therefore it is a really interesting P-gp inhibitor due to its ability to inhibit both P-gp function and expression.

  4. Impact of BCRP/MXR, MRP1 and MDR1/P-Glycoprotein on thermoresistant variants of atypical and classical multidrug resistant cancer cells

    DEFF Research Database (Denmark)

    Stein, Ulrike; Lage, Hermann; Jordan, Andreas;

    2002-01-01

    The impact of the ABC transporters breast cancer resistance protein/mitoxantrone resistance associated transporter (BCRP/MXR), multidrug resistance-associated protein 1 (MRP1) and multidrug resistance gene-1/P-glycoprotein (MDR1/PGP) on the multidrug resistance (MDR) phenotype in chemoresistance...... and thermoresistance was investigated in the parental human gastric carcinoma cell line EPG85-257P, the atypical MDR subline EPG85-257RNOV, the classical MDR subline EPG85-257RDB and their thermoresistant counterparts EPG85-257P-TR, EPG85-257RNOV-TR and EPG85-257RDB-TR. Within the atypical MDR subline EPG85-257RNOV...... was increased relative to thermosensitive sublines. Although it could be shown that the overexpressed ABC transporters were functionally active, however, no decreased drug accumulations of doxorubicin, mitoxantrone and rhodamine 123 were observed. Thus, expression of BCRP/MXR, MRP1 and MDR1/PGP was found...

  5. Nilotinib counteracts P-glycoprotein-mediated multidrug resistance and synergizes the antitumoral effect of doxorubicin in soft tissue sarcomas.

    Directory of Open Access Journals (Sweden)

    Victor Hugo Villar

    Full Text Available The therapeutic effect of doxorubicin (DXR in the treatment of soft tissue sarcomas (STS is limited by its toxicity and the development of multidrug resistance (MDR, the latter mainly induced by high expression of efflux pumps (e.g., P-glycoprotein [P-gp]. Therefore, the search for alternative therapies, which sensitize these tumors to chemotherapy while maintaining a low toxicity profile, is a rational approach. We assessed efficacy and molecular mechanisms involved in the antiproliferative effects of the tyrosine kinase inhibitors, nilotinib and imatinib, as single agents or in combination with DXR, in human synovial sarcoma SW982 and leiomyosarcoma SK-UT-1 cells. As single compound nilotinib (1-10 µM was more potent than imatinib inhibiting the growth of SK-UT-1 and SW982 cells by 33.5-59.6%, respectively. Importantly, only nilotinib synergized the antitumoral effect of DXR (0.05-0.5 µM by at least 2-fold, which clearly surpassed the mere sum of effects according to isobolographic analysis. Moreover, nilotinib in combination with DXR had a sustained effect on cell number (-70.3±5.8% even 12 days after withdrawal of drugs compared to DXR alone. On the molecular level, only nilotinib fully blocked FBS-induced ERK1 and p38 MAPK activation, hence, reducing basal and DXR-induced up-regulation of P-gp levels. Moreover, efflux activity of the MDR-related proteins P-gp and MRP-1 was inhibited, altogether resulting in intracellular DXR retention. In high-risk STS tumors 53.8% and 15.4% were positive for P-gp and MRP-1 expression, respectively, with high incidence of P-gp in synovial sarcoma (72.7%. In summary, nilotinib exhibits antiproliferative effects on cellular models of STS and sensitizes them to DXR by reverting DXR-induced P-gp-mediated MDR and inhibiting MRP-1 activity, leading to a synergistic effect with potential for clinical treatment.

  6. Lathyrol diterpenes as modulators of P-glycoprotein dependent multidrug resistance: structure-activity relationship studies on Euphorbia factor L3 derivatives.

    Science.gov (United States)

    Jiao, Wei; Wan, Zhongmin; Chen, Shuang; Lu, Runhua; Chen, Xiaozhen; Fang, Dongmei; Wang, Jiufeng; Pu, Shengcai; Huang, Xin; Gao, Haixiang; Shao, Huawu

    2015-05-14

    Five series of 37 new acylate and epoxide derivatives (3-39) of Euphorbia factor L3, a lathyrol diterpene isolated from Euphorbia lathyris, were designed by modifying the hydroxyl moiety of C-3, C-5, or C-15. Chemoreversal effects of the acylates on multidrug resistance (MDR) were evaluated in breast cancer multidrug-resistant MCF-7/ADR cells that overexpress P-glycoprotein (P-gp). Eight derivatives exhibited greater chemoreversal ability than verapamil (VRP) against adriamycin (ADR) resistance. Compounds 19 and 25 exhibited 4.8 and 4.0 times, respectively, more effective reversal ability than VRP against ADR resistance. To determine the key characteristics of Euphorbia factor L3 derivatives that contribute to MDR reversal, we conducted a structure-activity relationship study of these compounds. The simulation studies indicated different possible mechanisms and revealed the important influence of hydrophobic interactions and hydrogen bonds in the flexible cavity of P-gp.

  7. Asclepiasterol, a novel C21 steroidal glycoside derived from Asclepias curassavica, reverses tumor multidrug resistance by down-regulating P-glycoprotein expression

    OpenAIRE

    Yuan, Wei-Qi; Rong-rong ZHANG; Wang, Jun; Ma, Yan; Li, Wen-Xue; Jiang, Ren-Wang; Cai, Shao-Hui

    2016-01-01

    Multidrug resistance (MDR) mediated by P-glycoprotein (P-gp) is a major cause of cancer therapy failure. In this study, we identified a novel C21 steroidal glycoside, asclepiasterol, capable of reversing P-gp-mediated MDR. Asclepiasterol (2.5 and 5.0μM) enhanced the cytotoxity of P-gp substrate anticancer drugs in MCF-7/ADR and HepG-2/ADM cells. MDR cells were more responsive to paclitaxel in the presence of asclepiasterol, and colony formation of MDR cells was only reduced upon treatment wit...

  8. Rack1 Mediates the Interaction of P-Glycoprotein with Anxa2 and Regulates Migration and Invasion of Multidrug-Resistant Breast Cancer Cells

    Science.gov (United States)

    Yang, Yi; Wu, Na; Wang, Zhiyong; Zhang, Fei; Tian, Ran; Ji, Wei; Ren, Xiubao; Niu, Ruifang

    2016-01-01

    The emergence of multidrug resistance is always associated with more rapid tumor recurrence and metastasis. P-glycoprotein (P-gp), which is a well-known multidrug-efflux transporter, confers enhanced invasion ability in drug-resistant cells. Previous studies have shown that P-gp probably exerts its tumor-promoting function via protein-protein interaction. These interactions were implicated in the activation of intracellular signal transduction. We previously showed that P-gp binds to Anxa2 and promotes the invasiveness of multidrug-resistant (MDR) breast cancer cells through regulation of Anxa2 phosphorylation. However, the accurate mechanism remains unclear. In the present study, a co-immunoprecipitation coupled with liquid chromatography tandem mass spectrometry-based interactomic approach was performed to screen P-gp binding proteins. We identified Rack1 as a novel P-gp binding protein. Knockdown of Rack1 significantly inhibited proliferation and invasion of MDR cancer cells. Mechanistic studies demonstrated that Rack1 functioned as a scaffold protein that mediated the binding of P-gp to Anxa2 and Src. We showed that Rack1 regulated P-gp activity, which was necessary for adriamycin-induced P-gp-mediated phosphorylation of Anxa2 and Erk1/2. Overall, the findings in this study augment novel insights to the understanding of the mechanism employed by P-gp for promoting migration and invasion of MDR cancer cells. PMID:27754360

  9. 1-[3-(2-Hydroxyethylsulfanyl)propanoyl]-3,5-bis(benzylidene)-4-piperidones: A novel cluster of P-glycoprotein dependent multidrug resistance modulators.

    Science.gov (United States)

    Das, Umashankar; Pati, Hari N; Baráth, Zoltan; Csonka, Ákos; Molnár, Joseph; Dimmock, Jonathan R

    2016-02-15

    A series of 1-[3-(2-hydroxyethylsulfanyl)propanoyl]-3,5-bis(benzylidene)-4-piperidones 4a-e display promising P-glycoprotein dependent multidrug resistance (MDR) revertant properties and are significantly more potent than a reference drug verapamil when evaluated against L-5178Y MDR lymphoma cells. These dienones may be referred to as dual agents having both MDR revertant properties and tumour-selective cytotoxicity. In particular, 3,5-bis(4-chlorobenzylidene)-1-[3-(2-hydroxyethylsulfanyl]propanoyl-4-piperidone 4d emerged as a lead molecule for further development based on its MDR revertant properties, cytotoxic potencies and tumour-selective toxicity. The structure-activity relationships reveal important structural requirements for further designing of potent MDR revertants.

  10. Regulation of Multidrug Resistance P-Glycoprotein in the Developing Blood-Brain Barrier: Interplay between Glucocorticoids and Cytokines.

    Science.gov (United States)

    Iqbal, M; Baello, S; Javam, M; Audette, M C; Gibb, W; Matthews, S G

    2016-03-01

    P-glycoprotein (P-gp) encoded by Abcb1 provides protection to the developing brain from xenobiotics. P-gp in brain endothelial cells (BECs) derived from the developing brain microvasculature is up-regulated by glucocorticoids and inhibited by pro-inflammatory cytokines in vitro. However, little is known about how prenatal maternal glucocorticoid treatment can affect Abcb1/P-gp function and subsequent cytokine regulation in foetal BECs. We hypothesised that glucocorticoid exposure increases Abcb1/P-gp in the foetal brain microvasculature and enhances the sensitivity of Abcb1/P-gp in BECs to the inhibitory effects of cytokines. BECs isolated from dexamethasone- or vehicle-exposed foetal guinea pigs were cultured and treated with interleukin-1β, interleukin-6 or tumour necrosis factor-α, and Abcb1/P-gp expression and function were assessed. Prenatal dexamethasone exposure significantly increased Abcb1/P-gp expression/activity and cytokine receptor levels in BECs of the foetal brain microvasculature. Foetal dexamethasone exposure in vivo also increased the subsequent responsiveness of BECs to pro-inflammatory cytokines in vitro. In conclusion, maternal treatment with synthetic glucocorticoids appears to prematurely mature P-gp mediated drug resistance at the foetal BBB in vivo and profoundly impact the subsequent responsiveness of P-gp to pro-inflammatory cytokines in the foetal BEC. The significance of these findings to foetal brain protection against xenobiotics and other P-gp substrates in vivo requires further elaboration. However, the results of the present study may have implications for human pregnancy and foetal brain protection, particularly in cases of preterm birth combined with infection.

  11. Drug resistance in cortical and hippocampal slices from resected tissue of epilepsy patients: no significant impact of P-glycoprotein and Multidrug resistance associated proteins.

    Directory of Open Access Journals (Sweden)

    Nora eSandow

    2015-02-01

    Full Text Available Drug resistant patients undergoing epilepsy surgery have a good chance to become sensitive to anticonvulsant medication, suggesting that the resected brain tissue is responsible for drug resistance. Here, we address the question whether P-glycoprotein (Pgp and multidrug resistance associated proteins (MRPs expressed in the resected tissue contribute to drug resistance in vitro. Effects of anti-epileptic drugs (carbamazepine, sodium valproate, phenytoin and two unspecific inhibitors of Pgp and MRPs (verapamil and probenecid on seizure-like events induced in slices from 35 hippocampal and 35 temporal cortex specimens of altogether 51 patients (161 slices were studied. Although in slice preparations the blood brain barrier is not functional, we found that seizure-like events predominantly persisted in the presence of anticonvulsant drugs (90% and also in the presence of verapamil and probenecid (86%. Following subsequent co-administration of antiepileptic drugs and drug transport inhibitors, seizure-like events continued in 63% of 143 slices. Drug sensitivity in slices was recognized either as transition to recurrent epileptiform transients (30% or as suppression (7%, particularly by perfusion with carbamazepine in probenecid containing solutions (43%, 9%. Summarizing responses to co-administration from more than one slice per patient revealed that suppression of seizure-like activity in all slices was only observed in 7 % of patients. Patients whose tissue was completely or partially sensitive (65 % presented with higher seizure frequencies than those with resistant tissue (35 %. However, corresponding subgroups of patients don’t differ with respect to expression rates of drug transporters. Our results imply that parenchymal MRPs and Pgp are not responsible for drug resistance in resected tissue.

  12. Expression of P-glycoprotein, multidrug resistance-associated protein, glutathione-S-transferase pi and p53 in canine transmissible venereal tumor

    Directory of Open Access Journals (Sweden)

    Daniel G. Gerardi

    2014-01-01

    Full Text Available The overexpression of proteins P-glycoprotein (P-gp, multidrug resistance-associated protein (MRP1, mutant p53, and the enzyme glutathione-S-transferase (GSTpi are related to resistance to chemotherapy in neoplasms. This study evaluated the expression of these markers by immunohistochemistry in two groups of canine TVT, without history of prior chemotherapy (TVT1, n=9 and in TVTs presented unsatisfactory clinical response to vincristine sulfate (TVT2, n=5. The percentage of specimens positively stained for P-gp, MRP1, GSTpi and p53 were, respectively 88.8%, 0%, 44.5% and 22.2% in TVT1 and 80%, 0%, 80% and 0% in TVT2. In TVT1, one specimen presented positive expression for three markers and four specimens for two markers. In TVT2, three specimens expressed P-gp and GSTpi. In conclusion, the canine TVTs studied expressed the four markers evaluated, but just P-gp and GSTpi were significantly expressed, mainly at cytoplasm and cytoplasm and nuclei, respectively, either before chemotherapy as after vincristine sulfate exposure. Future studies are needed to demonstrate the function of these two markers in conferring multidrug resistance (MDR or predict the response to chemotherapy in canine TVT.

  13. REVERSION OF MULTIDRUG RESISTANCE IN THE P-GLYCOPROTEIN POSITIVE BREAST CANCER CELL LINE(MCF-7/ADR) BY INTRODUCTION OF HAMMERHEAD RIBOZYME

    Institute of Scientific and Technical Information of China (English)

    袁亚维; 张积仁; K.J.Scanlon; 陆长德; 祁国荣

    1998-01-01

    A hammerhead ribozyme which slte-specifically cleaved the GUC position in codon 880 of the mdrl mRNA was designed. The target site was chosen between the two ATP binding sites, which may be impottant for the function of the P-C-p as an ATPodependent pump. A DNA sequence encoding the riboxyme gene was then incorporated into a eukaryotic expression vector (pH 0 Apt-1 neo) and transfeeted into the breast cancer cell line MCF-7/Adr, which is resistant to adrlamycin and expresses the MDR phenmype. The ribozyme was stably expressed in the cell line by the RNA dot blotting assay. The result of Northern blot assay showed that the expressed ribozyme could decrease the level of mdrl mRNA expression by 83.5%; and the expressed ribozyme could inhiblte the formation of P-glycoprotein detected by immuno-cytochemistry assay and could reduce the cell''s resistance to adrimycin; this means that the resistant cells were 1 000-fold mcre resistant than the parental cell line(MCF-7), whereas those cell clones that showed ribozyme expression were only 6-fold more resistant than the parental cell line. These results show that a potentially useful tool is at hand which may inactivate MDR1 mRNA and revert the multidrug resistance phenotype.

  14. Gomisin A alters substrate interaction and reverses P-glycoprotein-mediated multidrug resistance in HepG2-DR cells.

    Science.gov (United States)

    Wan, Chi-Keung; Zhu, Guo-Yuan; Shen, Xiao-Ling; Chattopadhyay, Apurba; Dey, Saibal; Fong, Wang-Fun

    2006-09-28

    Through an extensive herbal drug screening program, we found that gomisin A, a dibenzocyclooctadiene compound isolated from Schisandra chinensis, reversed multidrug resistance (MDR) in Pgp-overexpressing HepG2-DR cells. Gomisin A was relatively non-toxic but without altering Pgp expression, it restored the cytotoxic actions of anticancer drugs such as vinblastine and doxorubicin that are Pgp substrates but may act by different mechanisms. Several lines of evidence suggest that gomisin A alters Pgp-substrate interaction but itself is neither a Pgp substrate nor competitive inhibitor. (1) First unlike Pgp substrates gomisin A inhibited the basal Pgp-associated ATPase (Pgp-ATPase) activity. (2) The cytotoxicity of gomisin A was not affected by Pgp competitive inhibitors such as verapamil. (3) Gomisin A acted as an uncompetitive inhibitor for Pgp-ATPase activity stimulated by the transport substrates verapamil and progesterone. (4) On the inhibition of rhodamine-123 efflux the effects of gomisin A and the competitive inhibitor verapamil were additive, so were the effects of gomisin A and the ATPase inhibitor vanadate. (5) Binding of transport substrates with Pgp would result in a Pgp conformational change favoring UIC-2 antibody reactivity but gomisin A impeded UIC-2 binding. (6) Photocrosslinking of Pgp with its transport substrate [125I]iodoarylazidoprazosin was inhibited by gomisin A in a concentration-dependent manner. Taken together our results suggest that gomisin A may bind to Pgp simultaneously with substrates and alters Pgp-substrate interaction.

  15. Saikosaponin A, an active glycoside from Radix bupleuri, reverses P-glycoprotein-mediated multidrug resistance in MCF-7/ADR cells and HepG2/ADM cells.

    Science.gov (United States)

    Ye, Rui-Ping; Chen, Zhen-Dong

    2017-02-01

    1. The expression and function of P-glycoprotein (P-gp) is associated with the phenotype of multidrug resistance (MDR). Saikosaponin A (SSA) is a triterpenoid saponin isolated from Radix Bupleuri. This study was mainly designed to understand effects of SSA on MDR in MCF-7/ADR and HepG2/ADM cells. 2. MDR reversal was examined as the alteration of cytotoxic drugs IC50 in resistant cells in the presence of SSA by MTT assay, and was compared with the non-resistant cells. Apoptosis and uptake of P-gp substrates in the tumor cells were detected by flow cytometry. Western blot was performed to assay the expression of P-gp. 3. Our results demonstrate SSA could increase the chemosensitivity of P-gp overexpressing HepG2/ADM and MCF-7/ADR cells to doxorubicin (DOX), vincristine (VCR) and paclitaxel. SSA promoted apoptosis of MCF-7/ADR cells in the presence of DOX. Moreover, it could also increase the retention of P-gp substrates DOX and rhodamine 123 in MCF-7/ADR cells, and decrease digoxin efflux ratio in Caco-2 cell monolayer. Finally, a mechanistic study showed that SSA reduced P-gp expression without affecting hydrolytic activity of P-gp. 4. In conclusion, our findings suggest that SSA could be further developed for sensitizing resistant cancer cells and used as an adjuvant therapy together with anticancer drugs to improve their therapeutic efficacies.

  16. Development of multidrug resistance due to multiple factors including P-glycoprotein overexpression under K-selection after MYC and HRAS oncogene activation.

    Science.gov (United States)

    Nakamura, Yukari; Sato, Hiroyuki; Motokura, Toru

    2006-05-15

    Multistep tumorigenesis is a form of microevolution consisting of mutation and selection. To clarify the role of selection modalities in tumor development, we examined two alternative evolutionary conditions, r-selection in sparse culture, which allows cells to proliferate rapidly, and K-selection in confluent culture, in which overcrowding constrains cell proliferation. Using MYC- and EJ-RAS-transformed rat embryo fibroblasts, we found that K-selected cells acquired and stably maintained multidrug resistance (MDR) to DOX, VCR, MTX and Ara-C. Then, we examined the involvement of a number of factors potentially causal of the development of MDR, that is, ploidy, Tp53 mutation, doubling time and the expression levels of genes related to drug resistance. Although ploidy status and Tp53 mutations did not correlate with MDR, we found that Abcb1/Mdr1, encoding P-glycoprotein (Pgp), was significantly upregulated after K-selection. Cyclosporin A, a competitive inhibitor of Pgp, increased the intracellular accumulation of DOX and reduced the resistance to it. Indeed, the population of Pgp-transfected cells significantly expanded under K-, but not under r-selection. In addition to Pgp upregulation, altered expression of other genes such as Cda/cytidine deaminase and Slc29a1/equilibrative nucleoside transporter 1 and prolonged doubling times were associated with MDR. This system reproduces events associated with MDR in vivo and would be useful for analysis of MDR development.

  17. Crystal structure of the antigen-binding fragment of a monoclonal antibody specific for the multidrug-resistance-linked ABC transporter human P-glycoprotein

    Energy Technology Data Exchange (ETDEWEB)

    Esser, Lothar; Shukla, Suneet; Zhou, Fei; Ambudkar, Suresh V.; Xia, Di

    2016-07-27

    P-glycoprotein (P-gp) is a polyspecific ATP-dependent transporter linked to multidrug resistance in cancers that plays important roles in the pharmacokinetics of a large number of drugs. The drug-resistance phenotype of P-gp can be modulated by the monoclonal antibody UIC2, which specifically recognizes human P-gp in a conformation-dependent manner. Here, the purification, sequence determination and high-resolution structure of the Fab fragment of UIC2 (UIC2/Fab) are reported. Purified UIC2/Fab binds human P-gp with a 1:1 stoichiometry. Crystals of UIC2/Fab are triclinic (space groupP1), with unit-cell parametersa= 40.67,b= 44.91,c= 58.09 Å, α = 97.62, β = 99.10, γ = 94.09°, and diffracted X-rays to 1.6 Å resolution. The structure was determined by molecular replacement and refined to 1.65 Å resolution. The asymmetric unit contains one molecule of UIC2/Fab, which exhibits a positively charged antigen-binding surface, suggesting that it might recognize an oppositely charged extracellular epitope of P-gp.

  18. Multi-drug resistance (MDR1 gene and P-glycoprotein influence on pharmacokinetic and pharmacodymanic of therapeutic drugs

    Directory of Open Access Journals (Sweden)

    Linardi Renata Lehn

    2006-01-01

    Full Text Available (MDR1 gene expressed in tumor cells and also in several normal tissues, such as intestine, liver, kidney, blood-brain barrier, spinal cord, and placenta. P-gp has been identified in mice, rat, bovine, monkey, rodents, and human beings and has been receiving a particular clinical relevance because this protein expression limits brain access and intestinal absorption of many drugs. This protein plays a role as a protective barrier against a wide variety of substrates, avoiding drug entry into the central nervous system. P-glycoprotein also interferes with drug bioavailability and disposition, including absorption, distribution, metabolization, and excretion, influencing pharmacokinetic and pharmacodynamic of drugs. Modulation of P-gp may help the efficacy of treatment of several diseases and can explain some adverse central nervous system effects induced by drugs after intravenous administration and the poor response of oral administration in patients. Alteration in P-gp expression or function has been associated with several diseases susceptibility in humans and animals. Furthermore, additional studies relating MDR1 and P-gp expression has an important clinical implication also in terms of treatment efficacy.

  19. Asclepiasterol, a novel C21 steroidal glycoside derived from Asclepias curassavica, reverses tumor multidrug resistance by down-regulating P-glycoprotein expression.

    Science.gov (United States)

    Yuan, Wei-Qi; Zhang, Rong-Rong; Wang, Jun; Ma, Yan; Li, Wen-Xue; Jiang, Ren-Wang; Cai, Shao-Hui

    2016-05-24

    Multidrug resistance (MDR) mediated by P-glycoprotein (P-gp) is a major cause of cancer therapy failure. In this study, we identified a novel C21 steroidal glycoside, asclepiasterol, capable of reversing P-gp-mediated MDR. Asclepiasterol (2.5 and 5.0μM) enhanced the cytotoxity of P-gp substrate anticancer drugs in MCF-7/ADR and HepG-2/ADM cells. MDR cells were more responsive to paclitaxel in the presence of asclepiasterol, and colony formation of MDR cells was only reduced upon treatment with a combination of asclepiasterol and doxorubicin. Consistent with these findings, asclepiasterol treatment increased the intracellular accumulation of doxorubicin and rhodamine 123 (Rh123) in MDR cells. Asclepiasterol decreased expression of P-gp protein without stimulating or suppressing MDR1 mRNA levels. Asclepiasterol-mediated P-gp suppression caused inhibition of ERK1/2 phosphorylation in two MDR cell types, and EGF, an activator of the MAPK/ERK pathway, reversed the P-gp down-regulation, implicating the MAPK/ERK pathway in asclepiasterol-mediated P-gp down-regulation. These results suggest that asclepiasterol could be developed as a modulator for reversing P-gp-mediated MDR in P-gp-overexpressing cancer variants.

  20. Diatrizoate, Iopromide and Iotrolan Enhanced Cytotoxicity of Daunorubicin in Multidrug Resistant K562/adr Cells: Impaired the Mitochondrial and Inhibited the P-Glycoprotein Function

    Directory of Open Access Journals (Sweden)

    Nitaya S.N. Ayudhya

    2009-01-01

    Full Text Available Multidrug resistance was an obstacle in cancer chemotherapy because the cells decreased their intracellular drug accumulation by energy-dependent compounds efflux pumps such as P-glycoprotein (P-gp. This study observed some iodinated radiographic contrast media, diatrizoate, iopromide and iotrolan affected the cellular energetic state and the kinetics of P-gp in drug-sensitive K562 and drug resistant K562/adr cell lines using spectrophotometer and spectrofluorometer. By colorimetric MTT assay, it was found that contrast media (0-3500 µM had no effect on both K562 and K562/adr cell viabilities, but in co-treatment with daunorubicin (DNR, diatrizoate decreased cell viability in K562/adr cells by decreasing ICso of DNR from 610.7 ±74.5 nM to 360±108.9 nM. The change in cellular energetic state was studied using rhodamine B as a probe to estimate mitochondrial membrane potential (ΔΨm. The results showed that 3500 µM diatrizoate decreased ΔΨm from 162.2±0.3 mV to 86.9±9.9 mV in K562/adr cells. The kinetics of P-gp-mediated efflux of DNR could be reduced by diatrizoate from 0 (no inhibition to 0.65±0.11. This inhibition could be partially prevented in co-incubation with 20 nM concanamycin A or 10 µM cytochalasin B. Among the three molecules, diatrizoate showed the best efficiency. It could be proposed for further studies that diatrizoate could be used as MDR identification or MDR imaging and also acted as MDR sensitizing agent in cancer treatments.

  1. P-glycoprotein attenuates DNA repair activity in multidrug-resistant cells by acting through the Cbp-Csk-Src cascade.

    Science.gov (United States)

    Lin, Li-Fang; Wu, Ming-Hsi; Pidugu, Vijaya Kumar; Ho, I-Ching; Su, Tsann-Long; Lee, Te-Chang

    2017-02-03

    Recent studies have demonstrated that P-glycoprotein (P-gp) expression impairs DNA interstrand cross-linking agent-induced DNA repair efficiency in multidrug-resistant (MDR) cells. To date, the detailed molecular mechanisms underlying how P-gp interferes with Src activation and subsequent DNA repair activity remain unclear. In this study, we determined that the C-terminal Src kinase-binding protein (Cbp) signaling pathway involved in the negative control of Src activation is enhanced in MDR cells. We also demonstrated that cells that ectopically express P-gp exhibit reduced activation of DNA damage response regulators, such as ATM, Chk2, Braca1 and Nbs1 and hence attenuated DNA double-strand break repair capacity and become more susceptible than vector control cells to DNA interstrand cross-linking (ICL) agents. Moreover, we demonstrated that P-gp can not only interact with Cbp and Src but also enhance the formation of inhibitory C-terminal Src kinase (Csk)-Cbp complexes that reduce phosphorylation of the Src activation residue Y416 and increase phosphorylation of the Src negative regulatory residue Y527. Notably, suppression of Cbp expression in MDR cells restores cisplatin-induced Src activation, improves DNA repair capacity, and increases resistance to ICL agents. Ectopic expression of Cbp attenuates cisplatin-induced Src activation and increases the susceptibility of cells to ICL agents. Together, the current results indicate that P-gp inhibits DNA repair activity by modulating Src activation via Cbp-Csk-Src cascade. These results suggest that DNA ICL agents are likely to have therapeutic potential against MDR cells with P-gp-overexpression.

  2. Oleanolic and maslinic acid sensitize soft tissue sarcoma cells to doxorubicin by inhibiting the multidrug resistance protein MRP-1, but not P-glycoprotein.

    Science.gov (United States)

    Villar, Victor Hugo; Vögler, Oliver; Barceló, Francisca; Gómez-Florit, Manuel; Martínez-Serra, Jordi; Obrador-Hevia, Antònia; Martín-Broto, Javier; Ruiz-Gutiérrez, Valentina; Alemany, Regina

    2014-04-01

    The pentacyclic triterpenes oleanolic acid (OLA) and maslinic acid (MLA) are natural compounds present in many plants and dietary products consumed in the Mediterranean diet (e.g., pomace and virgin olive oils). Several nutraceutical activities have been attributed to OLA and MLA, whose antitumoral effects have been extensively evaluated in human adenocarcinomas, but little is known regarding their effectiveness in soft tissue sarcomas (STS). We assessed efficacy and molecular mechanisms involved in the antiproliferative effects of OLA and MLA as single agents or in combination with doxorubicin (DXR) in human synovial sarcoma SW982 and leiomyosarcoma SK-UT-1 cells. As single compound, MLA (10-100 μM) was more potent than OLA, inhibiting the growth of SW982 and SK-UT-1 cells by 70.3 ± 1.11% and 68.8 ± 1.52% at 80 μM, respectively. Importantly, OLA (80 μM) or MLA (30 μM) enhanced the antitumoral effect of DXR (0.5-10 μM) by up to 2.3-fold. On the molecular level, efflux activity of the multidrug resistance protein MRP-1, but not of the P-glycoprotein, was inhibited. Most probably as a consequence, DXR accumulated in these cells. Kinetic studies showed that OLA behaved as a competitive inhibitor of substrate-mediated MRP-1 transport, whereas MLA acted as a non-competitive one. Moreover, none of both triterpenes induced a compensatory increase in MRP-1 expression. In summary, OLA or MLA sensitized cellular models of STS to DXR and selectively inhibited MRP-1 activity, but not its expression, leading to a higher antitumoral effect possibly relevant for clinical treatment.

  3. Reversion effects of curcumin on multidrug resistance of MNNG/HOS human osteosarcoma cells in vitro and in vivo through regulation of P-glycoprotein

    Institute of Scientific and Technical Information of China (English)

    SI Meng; ZHAO Jie; LI Xin; TIAN Ji-guang; LI Yong-gang; LI Jian-min

    2013-01-01

    Background P-glycoprotein (P-gp) encoded by ATP-binding cassette sub-family B member 1 (ABCB1) gene is a kind of ATP-dependent drug transporter,which plays important roles in multidrug resistance (MDR) of human cancers,such as osteosarcoma.Curcumin is a natural phenolic coloring compound originating from the rhizomes of Curcuma longa,which is proved to possess antitumor biological activities including reversion of MDR.However,the effect and molecular mechanisms of curcumin to osteosarcoma MDR remain unclear.Methods We established a human osteosarcoma drug-resistant cell line MNNG/HOS/MTX by pulse exposure to methotrexate (MTX) and verified that the new cell lines were cross-resistant to other anticancer agents.Then,according to the cytotoxicity assay,we reversed MDR of MNNG/HOS/MTX by 30 μmol/L curcumin,and detected the mechanisms of curcumin reversing MDR through Real-time PCR,Western blotting assay,and Rhodamine123 (Rh123)transport test.Finally,we evaluated the effect of curcumin reversing MDR in vivo by MNNG/HOS/MTX cells xenograft-nude mice model.Results MNNG/HOS/MTX was proved to be a human osteosarcoma MDR cell line.MTT tumor chemosensitivity test indicates that 30 μmol/L curcumin attenuates the half maximal inhibitory concentration (IC50) and resistance index (RI)to MTX,diamminedichloroplatinum (DDP),adriamycin (ADM),ifosfamide (IFO),and epirubicin (EPI) in MNNG/HOS/MTX cells (P <0.05).Real-time PCR and Western blotting assays demonstrated that curcumin down-regulated P-gp expression of MNNG/HOS/MTX cells.Rh123 transport test showed that curcumin inhibited the transport function of P-gp in vitro.In vivo studies showed that curcumin displayed the features of sensitizing antitumor drugs and inhibiting the proliferation,invasion,and metastasis of osteosarcoma MDR cells.Conclusion Down-regulation of P-gp and inhibition of the function of P-gp efflux pump may contribute to MDR reversion induced by curcumin in vitro and in vivo.

  4. Interaction of the P-Glycoprotein Multidrug Transporter with Sterols.

    Science.gov (United States)

    Clay, Adam T; Lu, Peihua; Sharom, Frances J

    2015-11-01

    The ABC transporter P-glycoprotein (Pgp, ABCB1) actively exports structurally diverse substrates from within the lipid bilayer, leading to multidrug resistance. Many aspects of Pgp function are altered by the phospholipid environment, but its interactions with sterols remain enigmatic. In this work, the functional interaction between purified Pgp and various sterols was investigated in detergent solution and proteoliposomes. Fluorescence studies showed that dehydroergosterol, cholestatrienol, and NBD-cholesterol interact intimately with Pgp, resulting in both quenching of protein Trp fluorescence and enhancement of sterol fluorescence. Kd values indicated binding affinities in the range of 3-9 μM. Collisional quenching experiments showed that Pgp-bound NBD-cholesterol was protected from the external milieu, resonance energy transfer was observed between Pgp Trp residues and the sterol, and the fluorescence emission of bound sterol was enhanced. These observations suggested an intimate interaction of bound sterols with the transporter at a protected nonpolar site. Cholesterol hemisuccinate altered the thermal unfolding of Pgp and greatly stabilized its basal ATPase activity in both a detergent solution and reconstituted proteoliposomes of certain phospholipids. Other sterols, including dehydroergosterol, did not stabilize the basal ATPase activity of detergent-solubilized Pgp, which suggests that this is not a generalized sterol effect. The phospholipid composition and cholesterol hemisuccinate content of Pgp proteoliposomes altered the basal ATPase and drug transport cycles differently. Sterols may interact with Pgp and modulate its structure and function by occupying part of the drug-binding pocket or by binding to putative consensus cholesterol-binding (CRAC/CARC) motifs located within the transmembrane domains.

  5. Novel 5-oxo-hexahydroquinoline derivatives: design, synthesis, in vitro P-glycoprotein-mediated multidrug resistance reversal profile and molecular dynamics simulation study

    Science.gov (United States)

    Shahraki, Omolbanin; Edraki, Najmeh; Khoshneviszadeh, Mehdi; Zargari, Farshid; Ranjbar, Sara; Saso, Luciano; Firuzi, Omidreza; Miri, Ramin

    2017-01-01

    Overexpression of the efflux pump P-glycoprotein (P-gp) is one of the important mechanisms of multidrug resistance (MDR) in many tumor cells. In this study, 26 novel 5-oxo-hexahydroquinoline derivatives containing different nitrophenyl moieties at C4 and various carboxamide substituents at C3 were designed, synthesized and evaluated for their ability to inhibit P-gp by measuring the amount of rhodamine 123 (Rh123) accumulation in uterine sarcoma cells that overexpress P-gp (MES-SA/Dx5) using flow cytometry. The effect of compounds with highest MDR reversal activities was further evaluated by measuring the alterations of MES-SA/Dx5 cells’ sensitivity to doxorubicin (DXR) using MTT assay. The results of both biological assays indicated that compounds bearing 2-nitrophenyl at C4 position and compounds with 4-chlorophenyl carboxamide at C3 demonstrated the highest activities in resistant cells, while they were devoid of any effect in parental nonresistant MES-SA cells. One of the active derivatives, 5c, significantly increased intracellular Rh123 at 100 µM, and it also significantly reduced the IC50 of DXR by 70.1% and 88.7% at 10 and 25 µM, respectively, in MES-SA/Dx5 cells. The toxicity of synthesized compounds against HEK293 as a noncancer cell line was also investigated. All tested derivatives except for 2c compound showed no cytotoxicity. A molecular dynamics simulation study was also performed to investigate the possible binding site of 5c in complex with human P-gp, which showed that this compound formed 11 average H-bonds with Ser909, Thr911, Arg547, Arg543 and Ser474 residues of P-gp. A good agreement was found between the results of the computational and experimental studies. The findings of this study show that some 5-oxo-hexahydroquinoline derivatives could serve as promising candidates for the discovery of new agents for P-gp-mediated MDR reversal. PMID:28243063

  6. Novel 5-oxo-hexahydroquinoline derivatives: design, synthesis, in vitro P-glycoprotein-mediated multidrug resistance reversal profile and molecular dynamics simulation study.

    Science.gov (United States)

    Shahraki, Omolbanin; Edraki, Najmeh; Khoshneviszadeh, Mehdi; Zargari, Farshid; Ranjbar, Sara; Saso, Luciano; Firuzi, Omidreza; Miri, Ramin

    2017-01-01

    Overexpression of the efflux pump P-glycoprotein (P-gp) is one of the important mechanisms of multidrug resistance (MDR) in many tumor cells. In this study, 26 novel 5-oxo-hexahydroquinoline derivatives containing different nitrophenyl moieties at C4 and various carboxamide substituents at C3 were designed, synthesized and evaluated for their ability to inhibit P-gp by measuring the amount of rhodamine 123 (Rh123) accumulation in uterine sarcoma cells that overexpress P-gp (MES-SA/Dx5) using flow cytometry. The effect of compounds with highest MDR reversal activities was further evaluated by measuring the alterations of MES-SA/Dx5 cells' sensitivity to doxorubicin (DXR) using MTT assay. The results of both biological assays indicated that compounds bearing 2-nitrophenyl at C4 position and compounds with 4-chlorophenyl carboxamide at C3 demonstrated the highest activities in resistant cells, while they were devoid of any effect in parental nonresistant MES-SA cells. One of the active derivatives, 5c, significantly increased intracellular Rh123 at 100 µM, and it also significantly reduced the IC50 of DXR by 70.1% and 88.7% at 10 and 25 µM, respectively, in MES-SA/Dx5 cells. The toxicity of synthesized compounds against HEK293 as a noncancer cell line was also investigated. All tested derivatives except for 2c compound showed no cytotoxicity. A molecular dynamics simulation study was also performed to investigate the possible binding site of 5c in complex with human P-gp, which showed that this compound formed 11 average H-bonds with Ser909, Thr911, Arg547, Arg543 and Ser474 residues of P-gp. A good agreement was found between the results of the computational and experimental studies. The findings of this study show that some 5-oxo-hexahydroquinoline derivatives could serve as promising candidates for the discovery of new agents for P-gp-mediated MDR reversal.

  7. Expression and significance of glucose transporter-1, P-glycoprotein, multidrug resistance-associated protein and glutathione S-transferase-π in laryngeal carcinoma

    Science.gov (United States)

    MAO, ZHONG-PING; ZHAO, LI-JUN; ZHOU, SHUI-HONG; LIU, MENG-QIN; TAN, WEI-FENG; YAO, HONG-TIAN

    2015-01-01

    Increasing glucose transporter-1 (GLUT-1) activity is one of the most important ways to increase the cellular influx of glucose. We previously demonstrated that increased GLUT-1 expression was an independent predictor of survival in patients with laryngeal carcinoma. Thus, GLUT-1 may present a novel therapeutic target in laryngeal carcinoma. In this study, the expression of GLUT-1, P-glycoprotein (P-gp), multidrug resistance-associated protein 1 (MRP1) and glutathione S-transferase-π (GST-π) in laryngeal carcinomas was investigated by immunohistochemistry. Additionally, possible correlations between GLUT-1 and P-gp, MRP1 and GST-π and various clinicopathological parameters were analyzed. In this study, 52.9% (18/34), 58.8% (20/34), 20.6% (7/34) and 58.8% (20/34) of the laryngeal carcinomas were positive for GLUT-1, P-gp, MRP1 and GST-π, respectively. The expression of GLUT-1, P-gp, MRP1 and GST-π was higher in laryngeal carcinoma specimens when compared with laryngeal precancerous lesions (P<0.05). Pearson’s correlation analysis showed correlations between GLUT-1 and P-gp (r=0.364; P=0.034), GLUT-1 and MRP1 (r=0.359; P=0.037) and P-gp and GST-π (r=0.426; P=0.012). GLUT-1 expression was found to significantly correlate with tumor-node-metastasis classification (P=0.02) and clinical stage (P=0.037). Furthermore, P-gp was found to significantly correlate with clinical stage (P=0.026). Univariate analysis showed that MRP1 expression was significantly associated with poor survival (c2=5.16; P=0.023). Multivariate analysis revealed that lymph node metastasis (P=0.009) and MRP1 overexpression (P=0.023) were significant predictors of poor survival. In the present study, the expression of GLUT-1, P-gp, MRP1 and GST-π in laryngeal carcinomas was investigated, as well as the correlations between these proteins. P-gp was found to significantly correlate with clinical stage, while MRP1 overexpression was significantly associated with poor survival. PMID:25621055

  8. Nude mice multi-drug resistance model of orthotopic transplantation of liver neoplasm and Tc-99m MIBI SPECT on p-glycoprotein

    Institute of Scientific and Technical Information of China (English)

    Yu Han; Xiao-Ping Chen; Zhi-Yong Huang; Hong Zhu

    2005-01-01

    AIM: To establish a model of drug-resistant neoplasms using a nude mice model, orthotopic transplantation of liver neoplasm and sporadic abdominal chemotherapy.METHODS: Hepatocellular carcinoma cells HepG2 were cultured and injected subdermally to form the tumorsupplying mice. The orthotopic drug-resistant tumors were formed by implanting the tumor bits under the envelope of the mice liver and induced by abdominal chemotherapy with Pharmorubicin. Physical examination, ultrasonography, spiral CT and visual inspection were used to examine tumor progression. RT-PCR and immunohistochemistry wereused to detect expression of mdr1 mRNA and its encodedprotein p-glycoprotein (p-gp). Tc-99m sestamibi scintigraphy was performed by obtaining planar abdominal images at 20 min after injection, and the liver/heart ratios werecalculated.RESULTS: Post-implantation mortality was 0% (0/25),tumor implantation success was 90% (22/25), and the rate of implanting successfully for the second time was 100% (3/3). Tumor induction using Pharmorubicin was 80% (16/20). The mdr1 mRNA expression of the induced group was 23 times higher than that of the control group, and p-gp protein expression was 13-fold higher compared to the control group. The liver/heart ratio (as assessed in vivo, using Tc-99m radiography) was decreased significantly in the induced group as compared to the control group. CONCLUSION: We have established an in vivo model of mdr1 in nude mice by orthotopic transplantation of liver neoplasm coupled to chemotherapy. We propose that identification of drug resistance as characterized by decreased 99mTc-ppm radiography due to enhanced clearance by p-gp may be useful in detecting in vivo drug resistance, as well as a useful tool in designing more effective therapies.

  9. Pentamidine movement across the murine blood-brain and blood-cerebrospinal fluid barriers: effect of trypanosome infection, combination therapy, P-glycoprotein, and multidrug resistance-associated protein.

    Science.gov (United States)

    Sanderson, Lisa; Dogruel, Murat; Rodgers, Jean; De Koning, Harry Pieter; Thomas, Sarah Ann

    2009-06-01

    During the first stage of human African trypanosomiasis (HAT), Trypanosoma brucei gambiense is found mainly in the blood, and pentamidine treatment is used. Pentamidine is predominantly ineffective once the parasites have invaded the central nervous system (CNS). This lack of efficacy is thought to be due to the inability of pentamidine to cross the blood-brain barrier, although this has never been explored directly. This study addresses this using brain perfusion in healthy mice, P-glycoprotein-deficient mice, and in a murine model of HAT (T. brucei brucei). The influence of additional antitrypanosomal drugs on pentamidine delivery to the CNS also was investigated. Results revealed that [(3)H]pentamidine can cross the blood-brain barrier, although a proportion was retained by the capillary endothelium and failed to reach the healthy or trypanosome-infected brain (up to day 21 p.i.). The CNS distribution of pentamidine was increased in the final (possibly terminal) stage of trypanosome infection, partly because of loss of barrier integrity (days 28-35 p.i.) as measured by [(14)C]sucrose and [(3)H]suramin. Furthermore, pentamidine distribution to the CNS involved influx and efflux [via P-glycoprotein and multidrug resistance-associated protein (MRP)] transporters and was affected by the other antitrypanosomal agents, suramin, melarsoprol, and nifurtimox, but not eflornithine. These interactions could contribute to side effects or lead to the development of parasite resistance to the drugs. Thus, great care must be taken when designing drug combinations containing pentamidine or other diamidine analogs. However, coadministration of P-glycoprotein and/or MRP inhibitors with pentamidine or other diamidines might provide a means of improving efficacy against CNS stage HAT.

  10. Synthesis of new steroidal inhibitors of P-glycoprotein-mediated multidrug resistance and biological evaluation on K562/R7 erythroleukemia cells.

    Science.gov (United States)

    de Ravel, Marc Rolland; Alameh, Ghina; Melikian, Maxime; Mahiout, Zahia; Emptoz-Bonneton, Agnès; Matera, Eva-Laure; Lomberget, Thierry; Barret, Roland; Rocheblave, Luc; Walchshofer, Nadia; Beltran, Sonia; El Jawad, Lucienne; Mappus, Elisabeth; Grenot, Catherine; Pugeat, Michel; Dumontet, Charles; Le Borgne, Marc; Cuilleron, Claude Yves

    2015-02-26

    A simple route for improving the potency of progesterone as a modulator of P-gp-mediated multidrug resistance was established by esterification or etherification of hydroxylated 5α/β-pregnane-3,20-dione or 5β-cholan-3-one precursors. X-ray crystallography of representative 7α-, 11α-, and 17α-(2'R/S)-O-tetrahydropyranyl ether diastereoisomers revealed different combinations of axial-equatorial configurations of the anomeric oxygen. Substantial stimulation of accumulation and chemosensitization was observed on K562/R7 erythroleukemia cells resistant to doxorubicin, especially using 7α,11α-O-disubstituted derivatives of 5α/β-pregnane-3,20-dione, among which the 5β-H-7α-benzoyloxy-11α-(2'R)-O-tetrahydropyranyl ether 22a revealed promising properties (accumulation index 2.9, IC50 0.5 μM versus 1.2 and 10.6 μM for progesterone), slightly overcoming those of verapamil and cyclosporin A. Several 7α,12α-O-disubstituted derivatives of 5β-cholan-3-one proved even more active, especially the 7α-O-methoxymethyl-12α-benzoate 56 (accumulation index 3.8, IC50 0.2 μM). The panel of modulating effects from different O-substitutions at a same position suggests a structural influence of the substituent completing a simple protection against stimulating effects of hydroxyl groups on P-gp-mediated transport.

  11. Is Rhodamine 123 an Appropriate Fluorescent Probe to Assess P-Glycoprotein Mediated Multidrug Resistance in Vinblastine-Resistant CHO Cells?

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    Jordi Pétriz

    1997-01-01

    Full Text Available Cellular drug resistance, which involves several mechanisms such as P‐glycoprotein (P‐gp overexpression, kinetic and metabolic quiescence, or the increase in the intracellular levels of glutathione, limits the effectiveness of cancer treatment. It has been reported that functional assessment of the cationic dye rhodamine 123 (Rho123 efflux reveals accurately the drug‐resistant phenotype. To study cellular drug resistance, we have obtained a CHO‐K1 derived cell line resistant to vinblastine by means of multistep selection. This cell line (CHOVBR displays high reactivity with a monoclonal antibody (MAb (C219 directed against an internal domain of P‐gp, and an active Rho123 efflux, as shown by parallel flow cytometric and fluorometric assays. However, under similar experimental conditions, the drug‐sensitive parental cell line CHO‐K1 (as well as the myeloblastic KG1 and KG1a cell lines, was also able to pump Rho123 out. These parental CHO‐K1 cells had a very low reactivity against the C219 Mab, as confirmed by Western blot analysis. Both vinblastine and verapamil inhibited Rho123 efflux in CHO‐K1 cells, but had no effect on CHOVBR cultures. Also, deprivation of vinblastine for one month did not affect Rho123 efflux in these cells. Our results suggest that the activity of P‐gp appears to be essential, but not sufficient to confer drug resistance, and that Rho123‐based functional assays of drug resistance should be evaluated for each cellular experimental model.

  12. Coniferyl Ferulate, a Strong Inhibitor of Glutathione S-Transferase Isolated from Radix Angelicae sinensis, Reverses Multidrug Resistance and Downregulates P-Glycoprotein

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    Chang Chen

    2013-01-01

    Full Text Available Glutathione S-transferase (GST is the key enzyme in multidrug resistance (MDR of tumour. Inhibition of the expression or activity of GST has emerged as a promising therapeutic strategy for the reversal of MDR. Coniferyl ferulate (CF, isolated from the root of Angelica sinensis (Oliv. Diels (Radix Angelicae sinensis, RAS, showed strong inhibition of human placental GST. Its 50% inhibition concentration (IC50 was 0.3 μM, which was greater than a known GSTP1-1 inhibitor, ethacrynic acid (EA, using the established high-throughput screening model. Kinetic analysis and computational docking were used to examine the mechanism of GST inhibition by CF. Computational docking found that CF could be fully docked into the gorge of GSTP1-1. The further exploration of the mechanisms showed that CF was a reversible noncompetitive inhibitor with respect to GSH and CDNB, and it has much less cytotoxicity. Apoptosis and the expression of P-gp mRNA were evaluated in the MDR positive B-MD-C1 (ADR+/+ cell line to investigate the MDR reversal effect of CF. Moreover, CF showed strong apoptogenic activity and could markedly decrease the overexpressed P-gp. The results demonstrated that CF could inhibit GST activity in a concentration-dependent manner and showed a potential MDR reversal effect for antitumour adjuvant therapy.

  13. The synthesis and evaluation of a solution phase indexed combinatorial library of non-natural polyenes for reversal of P-glycoprotein mediated multidrug resistance.

    Science.gov (United States)

    Andrus, M B; Turner, T M; Sauna, Z E; Ambudkar, S V

    2000-08-11

    A combinatorial library of polyenes, based on (-)-stipiamide, has been constructed and evaluated for the discovery of new multidrug resistance reversal agents. A palladium coupling was used to react each individual vinyl iodide with a mixture of the seven acetylenes at near 1:1 stoichiometry. The coupling was also used to react each individual acetylene with the mixture of six vinyl iodides to create 13 pools indexed in two dimensions for a total of 42 compounds. Individual compounds were detected at equimolar concentration. The vinyl iodides, made initially using a crotylborane addition to generate the anti1,2-hydroxylmethyl products, were now made using a more efficient norephedrine propionate boron enolate aldol reaction. The indexed approach, ideally suited for cellular assays that involve membrane-bound targets, allowed for the rapid identification of reversal agents using assays with drug-resistant human breast cancer MCF7-adrR cells. Intersections of potent pools identified new compounds with promising activity. Aryl dimension pools showed R = ph and naphthyl as the most potent. The acetylene dimension had R' = phenylalaninol and alaninol as the most potent. Isolated individual compounds, both active and nonpotent, were assayed to confirm the library results. The most potent new compound was 4ek (R = naphthyl, R' = phenylaninol) at 1.45 microM. Other nonnatural individual naphthyl-amide compounds showed potent MDR reversal including the morpholino-amide 4ej (1.69 microM). Synergistic activities attributed to the two ends of the molecule were also identified. Direct interaction with Pgp was established by ATPase and photoaffinity displacement assays. The results indicate that both ends of the polyene reversal agent are involved in Pgp interaction and can be further modified for increased potency.

  14. pH-Responsive therapeutic solid lipid nanoparticles for reducing P-glycoprotein-mediated drug efflux of multidrug resistant cancer cells

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    Chen HH

    2015-08-01

    Full Text Available Hsin-Hung Chen,1 Wen-Chia Huang,2 Wen-Hsuan Chiang,2 Te-I Liu,2 Ming-Yin Shen,2,3 Yuan-Hung Hsu,4 Sung-Chyr Lin,1 Hsin-Cheng Chiu2 1Department of Chemical Engineering, National Chung Hsing University, Taichung, 2Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, 3Department of Surgery, National Taiwan University Hospital-Hsinchu Branch, 4Pharmaceutical Optimization Technology Division, Biomedical Technology and Device Research Laboratory, Industrial Technology Research Institute, Hsinchu, Taiwan Abstract: In this study, a novel pH-responsive cholesterol-PEG adduct-coated solid lipid nanoparticles (C-PEG-SLNs carrying doxorubicin (DOX capable of overcoming multidrug resistance (MDR breast cancer cells is presented. The DOX-loaded SLNs have a mean hydrodynamic diameter of ~100 nm and a low polydispersity index (under 0.20 with a high drug-loading efficiency ranging from 80.8% to 90.6%. The in vitro drug release profiles show that the DOX-loaded SLNs exhibit a pH-controlled drug release behavior with the maximum and minimum unloading percentages of 63.4% at pH 4.7 and 25.2% at pH 7.4, respectively. The DOX-loaded C-PEG-SLNs displayed a superior ability in inhibiting the proliferation of MCF-7/MDR cells. At a DOX concentration of 80 µM, the cell viabilities treated with C-PEG-SLNs were approximately one-third of the group treated with free DOX. The inhibition activity of C-PEG-SLNs could be attributed to the transport of C-PEG to cell membrane, leading to the change of the composition of the cell membrane and thus the inhibition of permeability glycoprotein activity. This hypothesis is supported by the confocal images showing the accumulation of DOX in the nuclei of cancer cells and the localization of C-PEG on the cell membranes. The results of in vivo study further demonstrated that the DOX delivered by the SLNs accumulates predominantly in tumor via enhanced permeability and retention effect, the

  15. pH-Responsive therapeutic solid lipid nanoparticles for reducing P-glycoprotein-mediated drug efflux of multidrug resistant cancer cells.

    Science.gov (United States)

    Chen, Hsin-Hung; Huang, Wen-Chia; Chiang, Wen-Hsuan; Liu, Te-I; Shen, Ming-Yin; Hsu, Yuan-Hung; Lin, Sung-Chyr; Chiu, Hsin-Cheng

    2015-01-01

    In this study, a novel pH-responsive cholesterol-PEG adduct-coated solid lipid nanoparticles (C-PEG-SLNs) carrying doxorubicin (DOX) capable of overcoming multidrug resistance (MDR) breast cancer cells is presented. The DOX-loaded SLNs have a mean hydrodynamic diameter of ~100 nm and a low polydispersity index (under 0.20) with a high drug-loading efficiency ranging from 80.8% to 90.6%. The in vitro drug release profiles show that the DOX-loaded SLNs exhibit a pH-controlled drug release behavior with the maximum and minimum unloading percentages of 63.4% at pH 4.7 and 25.2% at pH 7.4, respectively. The DOX-loaded C-PEG-SLNs displayed a superior ability in inhibiting the proliferation of MCF-7/MDR cells. At a DOX concentration of 80 μM, the cell viabilities treated with C-PEG-SLNs were approximately one-third of the group treated with free DOX. The inhibition activity of C-PEG-SLNs could be attributed to the transport of C-PEG to cell membrane, leading to the change of the composition of the cell membrane and thus the inhibition of permeability glycoprotein activity. This hypothesis is supported by the confocal images showing the accumulation of DOX in the nuclei of cancer cells and the localization of C-PEG on the cell membranes. The results of in vivo study further demonstrated that the DOX delivered by the SLNs accumulates predominantly in tumor via enhanced permeability and retention effect, the enhanced passive tumor accumulation due to the loose intercellular junctions of endothelial cells lining inside blood vessels at tumor site, and the lack of lymphatic drainage. The growth of MCF-7/MDR xenografted tumor on Balb/c nude mice was inhibited to ~400 mm(3) in volume as compared with the free DOX treatment group, 1,140 mm(3), and the group treated with 1,2 distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)] solid lipid nanoparticles, 820 mm(3). Analysis of the body weight of nude mice and the histology of organs and tumor after the

  16. Membrane fluidization by ether, other anesthetics, and certain agents abolishes P-glycoprotein ATPase activity and modulates efflux from multidrug-resistant cells.

    Science.gov (United States)

    Regev, R; Assaraf, Y G; Eytan, G D

    1999-01-01

    The anesthetics benzyl alcohol and the nonaromatic chloroform and diethyl ether, abolish P-glycoprotein (Pgp) ATPase activity in a mode that does not fit classical competitive, noncompetitive, or uncompetitive inhibition. At concentrations similar to those required for inhibition of ATPase activity, these anesthetics fluidize membranes leading to twofold acceleration of doxorubicin flip-flop across lipid membranes and prevent photoaffinity labeling of Pgp with [125I]-iodoarylazidoprazosin. Similar concentrations of ether proved nontoxic and modulated efflux from Pgp-overexpressing cells. A similar twofold acceleration of doxorubicin flip-flop rate across membranes was observed with neutral mild detergents, including Tween 20, Nonidet P-40 and Triton X-100, and certain Pgp modulators, such as verapamil and progesterone. Concentrations of these agents, similar to those required for membrane fluidization, inhibited Pgp ATPase activity in a mode similar to that observed with the anesthetics. The mode of inhibition, i.e. lack of evidence for classical enzyme inhibition and the correlation of Pgp ATPase inhibition with membrane fluidization over a wide range of concentrations and structures of drugs favors the direct inhibition of Pgp ATPase activity by membrane fluidization. The unusual sensitivity of Pgp to membrane fluidization, as opposed to acceleration of ATPase activity of ion transporters, could fit the proposed function of Pgp as a 'flippase', which is in close contact with the membrane core.

  17. Inhibition of P-glycoprotein, multidrug resistance-associated protein 2 and cytochrome P450 3A4 improves the oral absorption of octreotide in rats with portal hypertension.

    Science.gov (United States)

    Sun, Xiao-Yu; Duan, Zhi-Jun; Liu, Zhen; Tang, Shun-Xiong; Li, Yang; He, Shou-Cheng; Wang, Qiu-Ming; Chang, Qing-Yong

    2016-12-01

    The aim of the present study was to increase the intestinal transport of octreotide (OCT) by targeting the first-pass impact to identify a potential method for decreasing portal vein pressure (PVP) using oral OCT. Thus, the bioavailability of intestinally absorbed OCT was evaluated in normal rats and rats with portal hypertension (PH) that had been administered P-glycoprotein/multidrug resistance-associated protein 2/cytochrome P450 3A4 (P-gp/MRP2/CYP3A4) inhibitors. The mRNA and protein expression levels of P-gp, MRP2 and CYP3A4 were evaluated in normal and PH rats with or without OCT and the inhibitors using RT-PCR, western blot and immunohistochemical analyses. The potential effects of the inhibitor administration on PVP were also examined. The results suggest that P-gp, MRP2 and CYP3A4 play important roles in prohibiting the enteral absorption of OCT, particularly under a PH environment. Moreover, inhibitors of P-gp, MRP2 and CYP3A4 decrease the first-pass effects of OCT and effectively reduce PVP under PH conditions. Therefore, the present results suggest P-gp, MRP2 and CYP3A4 are key factors in the intestinal absorption of OCT. The inhibition of P-gp, MRP2 and CYP3A4 can markedly decrease the first-pass effects of OCT, and their use may facilitate the use of orally administered OCT.

  18. Clitocine reversal of P-glycoprotein associated multi-drug resistance through down-regulation of transcription factor NF-κB in R-HepG2 cell line.

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    Jianguo Sun

    Full Text Available Multidrug resistance (MDR is one of the major reasons for failure in cancer chemotherapy and its suppression may increase the efficacy of therapy. The human multidrug resistance 1 (MDR1 gene encodes the plasma membrane P-glycoprotein (P-gp that pumps various anti-cancer agents out of the cancer cell. R-HepG2 and MES-SA/Dx5 cells are doxorubicin induced P-gp over-expressed MDR sublines of human hepatocellular carcinoma HepG2 cells and human uterine carcinoma MES-SA cells respectively. Herein, we observed that clitocine, a natural compound extracted from Leucopaxillus giganteus, presented similar cytotoxicity in multidrug resistant cell lines compared with their parental cell lines and significantly suppressed the expression of P-gp in R-HepG2 and MES-SA/Dx5 cells. Further study showed that the clitocine increased the sensitivity and intracellular accumulation of doxorubicin in R-HepG2 cells accompanying down-regulated MDR1 mRNA level and promoter activity, indicating the reversal effect of MDR by clitocine. A 5'-serial truncation analysis of the MDR1 promoter defined a region from position -450 to -193 to be critical for clitocine suppression of MDR1. Mutation of a consensus NF-κB binding site in the defined region and overexpression of NF-κB p65 could offset the suppression effect of clitocine on MDR1 promoter. By immunohistochemistry, clitocine was confirmed to suppress the protein levels of both P-gp and NF-κB p65 in R-HepG2 cells and tumors. Clitocine also inhibited the expression of NF-κB p65 in MES-SA/Dx5. More importantly, clitocine could suppress the NF-κB activation even in presence of doxorubicin. Taken together; our results suggested that clitocine could reverse P-gp associated MDR via down-regulation of NF-κB.

  19. Di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone (Dp44mT) overcomes multidrug resistance by a novel mechanism involving the hijacking of lysosomal P-glycoprotein (Pgp).

    Science.gov (United States)

    Jansson, Patric J; Yamagishi, Tetsuo; Arvind, Akanksha; Seebacher, Nicole; Gutierrez, Elaine; Stacy, Alexandra; Maleki, Sanaz; Sharp, Danae; Sahni, Sumit; Richardson, Des R

    2015-04-10

    Multidrug resistance (MDR) is a major obstacle in cancer treatment. More than half of human cancers express multidrug-resistant P-glycoprotein (Pgp), which correlates with a poor prognosis. Intriguingly, through an unknown mechanism, some drugs have greater activity in drug-resistant tumor cells than their drug-sensitive counterparts. Herein, we investigate how the novel anti-tumor agent di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone (Dp44mT) overcomes MDR. Four different cell types were utilized to evaluate the effect of Pgp-potentiated lysosomal targeting of drugs to overcome MDR. To assess the mechanism of how Dp44mT overcomes drug resistance, cellular studies utilized Pgp inhibitors, Pgp silencing, lysosomotropic agents, proliferation assays, immunoblotting, a Pgp-ATPase activity assay, radiolabeled drug uptake/efflux, a rhodamine 123 retention assay, lysosomal membrane permeability assessment, and DCF (2',7'-dichlorofluorescin) redox studies. Anti-tumor activity and selectivity of Dp44mT in Pgp-expressing, MDR cells versus drug-sensitive cells were studied using a BALB/c nu/nu xenograft mouse model. We demonstrate that Dp44mT is transported by the lysosomal Pgp drug pump, causing lysosomal targeting of Dp44mT and resulting in enhanced cytotoxicity in MDR cells. Lysosomal Pgp and pH were shown to be crucial for increasing Dp44mT-mediated lysosomal damage and subsequent cytotoxicity in drug-resistant cells, with Dp44mT being demonstrated to be a Pgp substrate. Indeed, Pgp-dependent lysosomal damage and cytotoxicity of Dp44mT were abrogated by Pgp inhibitors, Pgp silencing, or increasing lysosomal pH using lysosomotropic bases. In vivo, Dp44mT potently targeted chemotherapy-resistant human Pgp-expressing xenografted tumors relative to non-Pgp-expressing tumors in mice. This study highlights a novel Pgp hijacking strategy of the unique dipyridylthiosemicarbazone series of thiosemicarbazones that overcome MDR via utilization of lysosomal Pgp transport activity.

  20. Involvement of CD147 on multidrug resistance through the regulation of P-glycoprotein expression in K562/ADR leukemic cell line

    Directory of Open Access Journals (Sweden)

    Aoranit Somno

    2016-01-01

    Full Text Available The relationship between P-gp and CD147 in the regulation of MDR in leukemic cells has not been reported. This study aimed to investigate the correlation between CD147 and P-gp in the regulation of drug resistance in the K562/ADR leukemic cell line. The results showed that drug-resistant K562/ADR cells expressed significantly higher P-gp and CD147 levels than drug-free K562/ADR cells. To determine the regulatory effect of CD147 on P-gp expression, anti-CD147 antibody MEM-M6/6 significantly decreased P-gp and CD147 mRNA and protein levels. This is the first report to show that CD147 mediates MDR in leukemia through the regulation of P-gp expression.

  1. Grape seed procyanidin reversal of p-glycoprotein associated multi-drug resistance via down-regulation of NF-κB and MAPK/ERK mediated YB-1 activity in A2780/T cells.

    Directory of Open Access Journals (Sweden)

    Bo-xin Zhao

    Full Text Available The expression and function of P-glycoprotein (P-gp is associated with the phenotype of multi-drug resistance (MDR, leading chemotherapy failure of patients suffered with cancer. Grape seed procyanidin(GSP is a natural polyphenol supplement with anti-inflammatory effect. Present study assessed a new use of GSP on the MDR reversal activity and its possible molecular mechanisms in MDR1-overpressing paclitaxel resistant ovarian cancer cells. Our results showed GSP significantly enhanced the cytotoxicity of paclitaxel and adriamycin in paclitaxel resistant A2780/T cells but its parental A2780 cells. Furthermore, GSP strongly inhibited P-gp expression by blocking MDR1 gene transcription, as well as, increased the intracellular accumulation of the P-gp substrate rhodamine-123 in A2780/T cells. Nuclear factor-κB(NF-κB activity, IκB degradation level and NF-κB/p65 nuclear translocation induced by lipopolysaccharide (LPS and receptor activator for nuclear factor-κB ligand (RANKL were markedly inhibited by pre-treatment with GSP. Meanwhile, GSP inhibited MAPK/ERK pathway by decreasing the phosphorylation of ERK1/2, resulting in reduced the Y-box binding protein 1 (YB-1 activation with blocking its nuclear translocation. Moreover, the up-regulation of P-gp expression, the activation of AKT/NF-κB and MAPK/ERK pathway induced by LPS was attenuated by GSP administration. Compared with PDTC and U1026, inhibitor of NF-κB and MAPK/ERK respectively, GSP showed the same tendency of down-regulating NF-κB and MAPK/ERK mediated YB-1 activities. Thus, GSP reverses P-gp associated MDR by inhibiting the function and expression of P-gp through down-regulation of NF-κB activity and MAPK/ERK pathway mediated YB-1 nuclear translocation, offering insight into the mechanism of reversing MDR by natural polyphenol supplement compounds. GSP could be a new potential MDR reversal agent used for combination therapy with chemotherapeutics in clinic.

  2. HIV-1 integrase inhibitors are substrates for the multidrug transporter MDR1-P-glycoprotein

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    Cara Andrea

    2007-03-01

    Full Text Available Abstract Background The discovery of diketoacid-containing derivatives as inhibitors of HIV-1 Integrase (IN (IN inhibitors, IINs has played a major role in validating this enzyme as an important target for antiretroviral therapy. Since the in vivo efficacy depends on access of these drugs to intracellular sites where HIV-1 replicates, we determined whether the IINs are recognized by the multidrug transporter MDR1-P-glycoprotein (P-gp thereby reducing their intracellular accumulation. To address the effect of IINs on drug transport, nine quinolonyl diketo acid (DKA derivatives active on the HIV-1 IN strand transfer (ST step and with EC50 ranging from 1.83 to >50 μm in cell-based assays were tested for their in vitro interaction with P-gp in the CEM-MDR cell system. IINs were investigated for the inhibition and induction of the P-gp function and expression as well as for multidrug resistance (MDR reversing ability. Results The HIV-1 IINs act as genuine P-gp substrates by inhibiting doxorubicin efflux and inducing P-gp functional conformation changes as evaluated by the modulation of UIC2 mAb epitope. Further, IINs chemosensitize MDR cells to vinblastine and induce P-gp expression in drug sensitive revertants of CEM-MDR cells. Conclusion To our knowledge, this is the first demonstration that HIV-1 IINs are P-gp substrates. This biological property may influence the absorption, distribution and elimination of these novels anti HIV-1 compounds.

  3. P-Glycoprotein and Drug Resistance in Systemic Autoimmune Diseases

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    Andrea Picchianti-Diamanti

    2014-03-01

    Full Text Available Autoimmune diseases such as systemic lupus erythematosus (SLE, rheumatoid arthritis (RA and psoriatic arthritis (PsA are chronic inflammatory disorders of unknown etiology characterized by a wide range of abnormalities of the immune system that may compromise the function of several organs, such as kidney, heart, joints, brain and skin. Corticosteroids (CCS, synthetic and biologic immunosuppressive agents have demonstrated the capacity to improve the course of autoimmune diseases. However, a significant number of patients do not respond or develop resistance to these therapies over time. P-glycoprotein (P-gp is a transmembrane protein that pumps several drugs out of the cell, including CCS and immunosuppressants; thus, its over-expression or hyper-function has been proposed as a possible mechanism of drug resistance in patients with autoimmune disorders. Recently, different authors have demonstrated that P-gp inhibitors, such as cyclosporine A (CsA and its analogue Tacrolimus, are able to reduce P-gp expression and or function in SLE, RA and PsA patients. These observations suggest that P-gp antagonists could be adopted to revert drug resistance and improve disease outcome. The complex inter-relationship among drug resistance, P-gp expression and autoimmunity still remains elusive.

  4. DUSP1 induces paclitaxel resistance through the regulation of p-glycoprotein expression in human ovarian cancer cells.

    Science.gov (United States)

    Kang, Yu-Seon; Seok, Hyun-Jeong; Jeong, Eun-Jeong; Kim, Yuna; Yun, Seok-Joong; Min, Jeong-Ki; Kim, Sun Jin; Kim, Jang-Seong

    2016-09-01

    The heterogeneity and genetic instability of ovarian cancer cells often lead to the development of drug resistance, closely related with the increased cancer-related mortality. In this study, we investigated the role of dual-specificity phosphatase 1 (DUSP1) in the development of the resistance in human ovarian cancer cells against paclitaxel. Overexpression of DUSP1 in HeyA8 human ovarian cancer cells (HeyA8-DUSP1) up-regulated the expression of the drug efflux pump, p-glycoprotein. Consequently, HeyA8-DUSP1 cells are highly resistant to paclitaxel, with the resistance comparable to that of a multi-drug resistance cell line (HeyA8-MDR). Moreover, over expression of DUSP1 significantly increased the activation of p38 MAPK, leaving the activation of ERK1/2 and JNK1/2 unaffected. Pharmacological suppression of p38 MAPK activity prevents the up-regulation of p-glycoprotein expression and the consequent resistance against paclitaxel in HeyA8-DUSP1 cells. By contrast, HeyA8-MDR cells expressed a significantly higher level of DUSP1, but treatment with small interference RNA against DUSP1 significantly suppressed the expression of p-glycoprotein and the resistance against paclitaxel in HeyA8-MDR cells. Ectopic expression of MKK3, an upstream activator of p38 MAPK, significantly up-regulated the expression of p-glycoprotein and increased the consequent resistance against paclitaxel in HeyA8 cells. Collectively, these data indicated that DUSP1 may induce the resistance against paclitaxel through the p38 MAPK-mediated overexpression of p-glycoprotein in human ovarian cancer cells.

  5. Contribution of mdr1b-type P-glycoprotein to okadaic acid resistance in rat pituitary GH3 cells.

    Science.gov (United States)

    Ritz, V; Marwitz, J; Sieder, S; Ziemann, C; Hirsch-Ernst, K I; Quentin, I; Steinfelder, H J

    1999-08-01

    Okadaic acid as well as other, structurally different, inhibitors of serine/threonine phosphatases 1 and 2A induce apoptosis in pituitary GH3 cells. Incubation with stepwise raised concentrations of okadaic acid resulted in the isolation of cells that were increasingly less sensitive to the cytotoxic effect of this agent. After about 18 months cells were selected that survived at 300 nM okadaic acid, which is about 30 times the initially lethal concentration. This study revealed that a major pharmacokinetic mechanism underlying cell survival was the development of a P-glycoprotein-mediated multidrug resistance (MDR) phenotype. The increase in mRNA levels of the mdr1b P-glycoprotein isoform correlated with the extent of drug resistance. Functional assays revealed that increasing drug resistance was paralleled by a decreased accumulation of rhodamine 123, a fluorescent dye which is a substrate of mdr1-mediated efflux activity. Resistance could be abolished by structurally different chemosensitizers of P-glycoprotein function like verapamil and reserpine but not by the leukotriene receptor antagonist MK571 which is a modulator of the multidrug resistance-associated protein (MRP). Okadaic acid resistance included cross-resistance to other cytotoxic agents that are substrates of mdr1-type P-glycoproteins, like doxorubicin and actinomycin D, but not to non-substrates of mdr1, e.g. cytosine arabinoside. Thus, functional as well as biochemical features support the conclusion that okadaic acid is a substrate of the mdr1-mediated efflux activity in rat pituitary GH3 cells. Maintenance of resistance after withdrawal of okadaic acid as well as metaphase spreads of 100 nM okadaic acid-resistant cells suggested a stable MDR genotype without indications for the occurrence of extrachromosomal amplifications, e.g. double minute chromosomes.

  6. Role of multidrug resistance in photodynamic therapy

    Science.gov (United States)

    Diddens, Heyke C.

    1992-06-01

    Multidrug resistance in cancer chemotherapy is a well established phenomenon. One of the most common phenotypical changes in acquired or intrinsic multidrug resistance in human tumor cells is the overexpression of the mdrl gene product P-glycoprotein, which acts as an active efflux pump. Increased levels of P-glycoprotein are associated with resistance to a variety of anticancer drugs commonly used in tumor chemotherapy like anthracyclins, vinca- alcaloids, epipodophyllotoxins or actinomycin D. We investigated the efficacy or photodynamic therapy in the treatment of tumor cells expressing the multidrug resistance phenotype. Our data show that multidrug resistant cells are highly cross resistant to the phototoxic stain rhodamine 123 but exhibit only low degrees of cross resistance (2 - 3 -folds) to the photosensitizers Photosan-3, Clorin-2, methylene blue and meso-tetra (4- sulfonatophenyl) porphine (TPPS4). Resistance is associated with a decrease in intracellular accumulation of the photosensitizer. Verapamil, a membrane active compound known to enhance drug sensitivity in multidrug resistant cells by inhibition of P-glycoprotein, also increases phototoxicity in multidrug resistant cells. Our results imply that tumors expressing the multidrug resistance phenotype might fail to respond to photochemotherapy with rhodamine 123. On the other hand, multidrug resistance may not play an important role in photodynamic therapy with Photosan-3, Chlorin-2, methylene blue or TPPS4.

  7. Complex interplay between the P-glycoprotein multidrug efflux pump and the membrane: its role in modulating protein function

    Directory of Open Access Journals (Sweden)

    Frances Jane Sharom

    2014-03-01

    Full Text Available Multidrug resistance in cancer is linked to expression of the P-glycoprotein multidrug transporter (Pgp, ABCB1, which exports many structurally diverse compounds from cells. Substrates first partition into the bilayer and then interact with a large flexible binding pocket within the transporter’s transmembrane regions. Pgp has been described as a hydrophobic vacuum cleaner or an outwardly-directed drug/lipid flippase. Recent X-ray crystal structures have shed some light on the nature of the drug-binding pocket and suggested routes by which substrates can enter it from the membrane. Detergents have profound effects on Pgp function, and several appear to be substrates. Biochemical and biophysical studies in vitro, some using purified reconstituted protein, have explored the effects of the membrane environment. They have demonstrated that Pgp is involved in a complex relationship with its lipid environment, which modulates the behaviour of its substrates, as well as various functions of the protein, including ATP hydrolysis, drug binding and drug transport. Membrane lipid composition and fluidity, phospholipid headgroup and acyl chain length all influence Pgp function. Recent studies focusing on thermodynamics and kinetics have revealed some important principles governing Pgp-lipid and substrate-lipid interactions, and how these affect drug binding and transport. In some cells, Pgp is associated with cholesterol-rich microdomains which may modulate its functions. The relationship between Pgp and cholesterol remains an open question; however it clearly affects several aspects of its function in addition to substrate-membrane partitioning. The action of Pgp modulators appears to depend on their membrane permeability, and membrane fluidizers and surfactants reverse drug resistance, likely via an indirect mechanism. A detailed understanding of how the membrane affects Pgp substrates and Pgp’s catalytic cycle may lead to new strategies to combat

  8. Overexpression of P-glycoprotein induces acquired resistance to imatinib in chronic myelogenous leukemia cells

    Institute of Scientific and Technical Information of China (English)

    Xing-Xiang Peng; Amit K. Tiwari; Hsiang-Chun Wu; Zhe-Sheng Chen

    2012-01-01

    Imatinib,a breakpoint cluster region (BCR)-Abelson murine leukemia (ABL) tyrosine kinase inhibitor (TKI),has revolutionized the treatment of chronic myelogenous leukemia (CML).However,development of multidrug resistance(MDR) limits the use of imatinib.In the present study,we aimed to investigate the mechanisms of cellular resistance to imatinib in CML.Therefore,we established an imatinib-resistant human CML cell line (K562-imatinib) through a stepwise selection process.While characterizing the phenotype of these cells,we found that K562-imatinib cells were 124.6-fold more resistant to imatinib than parental K562 cells.In addition,these cells were cross-resistant to second- and third-generation BCR-ABL TKIs.Western blot analysis and reverse transcription-polymerase chain reaction(RT-PCR) demonstrated that P-glycoprotein (P-gp) and MDR1 mRNA levels were increased in K562-imatinib cells.In addition,accumulation of [14C]6-mercaptopurine (6-MP) was decreased,whereas the ATP-dependent efflux of [14C] 6-MP and [3H]methotrexate transport were increased in K562-imatinib cells.These data suggest that the overexpression of P-gp may play a crucial role in acquired resistance to imatinib in CML K562-imatinib cells.

  9. Evaluation of the expression of P-glycoprotein in propoxur-resistant Caco-2 cells.

    Directory of Open Access Journals (Sweden)

    Shabnam Yazdian

    2014-10-01

    Full Text Available There is a great concern about the effect of propoxur, as one of the more common N-methyl carbamate pesticides, on human health due to its extensive use in agricultural and non-agricultural applications. Caco-2 cells became resistant to propoxur, and the resistance was confirmed through MTT assay. Then the cell membrane integrity and P-glycoprotein expression were measured by LDH assay and western blot analysis, respectively and compared to the parent cells.  Contrary to what was expected, the expression of P-glycoprotein in propoxur resistant cells was lower than parent cells.This study indicates that the resistance to propoxur may not be related to P-glycoprotein expression directly, since P-glycoprotein expression has decreased in these cells.

  10. Structures of the Multidrug Transporter P-glycoprotein Reveal Asymmetric ATP Binding and the Mechanism of Polyspecificity.

    Science.gov (United States)

    Esser, Lothar; Zhou, Fei; Pluchino, Kristen M; Shiloach, Joseph; Ma, Jichun; Tang, Wai-Kwan; Gutierrez, Camilo; Zhang, Alex; Shukla, Suneet; Madigan, James P; Zhou, Tongqing; Kwong, Peter D; Ambudkar, Suresh V; Gottesman, Michael M; Xia, Di

    2017-01-13

    P-glycoprotein (P-gp) is a polyspecific ATP-dependent transporter linked to multidrug resistance in cancer; it plays important roles in determining the pharmacokinetics of many drugs. Understanding the structural basis of P-gp, substrate polyspecificity has been hampered by its intrinsic flexibility, which is facilitated by a 75-residue linker that connects the two halves of P-gp. Here we constructed a mutant murine P-gp with a shortened linker to facilitate structural determination. Despite dramatic reduction in rhodamine 123 and calcein-AM transport, the linker-shortened mutant P-gp possesses basal ATPase activity and binds ATP only in its N-terminal nucleotide-binding domain. Nine independently determined structures of wild type, the linker mutant, and a methylated P-gp at up to 3.3 Å resolution display significant movements of individual transmembrane domain helices, which correlated with the opening and closing motion of the two halves of P-gp. The open-and-close motion alters the surface topology of P-gp within the drug-binding pocket, providing a mechanistic explanation for the polyspecificity of P-gp in substrate interactions.

  11. Structures of the Multidrug Transporter P-glycoprotein Reveal Asymmetric ATP Binding and the Mechanism of Polyspecificity*♦

    Science.gov (United States)

    Esser, Lothar; Zhou, Fei; Pluchino, Kristen M.; Shiloach, Joseph; Ma, Jichun; Tang, Wai-kwan; Gutierrez, Camilo; Zhang, Alex; Shukla, Suneet; Madigan, James P.; Zhou, Tongqing; Kwong, Peter D.; Ambudkar, Suresh V.; Gottesman, Michael M.; Xia, Di

    2017-01-01

    P-glycoprotein (P-gp) is a polyspecific ATP-dependent transporter linked to multidrug resistance in cancer; it plays important roles in determining the pharmacokinetics of many drugs. Understanding the structural basis of P-gp, substrate polyspecificity has been hampered by its intrinsic flexibility, which is facilitated by a 75-residue linker that connects the two halves of P-gp. Here we constructed a mutant murine P-gp with a shortened linker to facilitate structural determination. Despite dramatic reduction in rhodamine 123 and calcein-AM transport, the linker-shortened mutant P-gp possesses basal ATPase activity and binds ATP only in its N-terminal nucleotide-binding domain. Nine independently determined structures of wild type, the linker mutant, and a methylated P-gp at up to 3.3 Å resolution display significant movements of individual transmembrane domain helices, which correlated with the opening and closing motion of the two halves of P-gp. The open-and-close motion alters the surface topology of P-gp within the drug-binding pocket, providing a mechanistic explanation for the polyspecificity of P-gp in substrate interactions. PMID:27864369

  12. Multidrug efflux pumps: the structures of prokaryotic ATP-binding cassette transporter efflux pumps and implications for our understanding of eukaryotic P-glycoproteins and homologues.

    Science.gov (United States)

    Kerr, Ian D; Jones, Peter M; George, Anthony M

    2010-02-01

    One of the Holy Grails of ATP-binding cassette transporter research is a structural understanding of drug binding and transport in a eukaryotic multidrug resistance pump. These transporters are front-line mediators of drug resistance in cancers and represent an important therapeutic target in future chemotherapy. Although there has been intensive biochemical research into the human multidrug pumps, their 3D structure at atomic resolution remains unknown. The recent determination of the structure of a mouse P-glycoprotein at subatomic resolution is complemented by structures for a number of prokaryotic homologues. These structures have provided advances into our knowledge of the ATP-binding cassette exporter structure and mechanism, and have provided the template data for a number of homology modelling studies designed to reconcile biochemical data on these clinically important proteins.

  13. P-glycoprotein inhibition of drug resistant cell lines by nanoparticles.

    Science.gov (United States)

    Singh, Manu Smriti; Lamprecht, Alf

    2016-01-01

    Several pharmaceutical excipients are known for their ability to interact with cell membrane lipids and reverse the phenomenon of multidrug resistance (MDR) in cancer. Interestingly, many excipients act as stabilizers and are key ingredients in a variety of nano-formulations. In this study, representatives of ionic and non-ionic excipients were used as surface active agents in nanoparticle (NP) formulations to utilize their MDR reversing potential. In-vitro assays were performed to elucidate particle-cell interaction and accumulation of P-glycoprotein (P-gp) substrates-rhodamine-123 and calcein AM, in highly drug resistant glioma cell lines. Chemosensitization achieved using NPs and their equivalent dose of free excipients was assessed with the co-administered anti-cancer drug doxorubicin. Among the excipients used, non-ionic surfactant, Cremophor® EL, and cationic surfactant, cetyltrimethylammonuium bromide (CTAB), demonstrated highest P-gp modulatory activity in both free solution form (up to 7-fold lower IC50) and as a formulation (up to 4.7-fold lower IC50) as compared to doxorubicin treatment alone. Solutol® HS15 and Tween® 80 exhibited considerable chemosensitization as free solution but not when incorporated into a formulation. Sodium dodecyl sulphate (SDS)-based nanocarriers resulted in slightly improved cytotoxicity. Overall, the results highlight and envisage the usage of excipient in nano-formulations in a bid to improve chemosensitization of drug resistant cancer cells towards anti-cancer drugs.

  14. Levistolide A overcomes P-glycoprotein-mediated drug resistance in human breast carcinoma cells

    Institute of Scientific and Technical Information of China (English)

    Fei CHEN; Tao WANG; Jia WANG; Zi-qiang WANG; Ming QIAN

    2008-01-01

    Aim:The aim of the present study was to investigate the reversing effect of levistolide A (LA) on P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) in human breast carcinoma Bcap37/MDR1 cells. Methods:After chemotherapeu-tic drugs (adriamycin or vincristine) used alone or in combination with LA, cell proliferation was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazo-lium bromide assay and cell cycle distribution by flow cytometry. RT-PCR was used to detect MDR1 gene transcription and the Western blot assay was used to assess P-gp expression and the cleavages of poly(ADP-ribose) polymerase and caspase-3. Apoptosis was detected by terminal transferase-mediated dUTP nick end-labeling assay. Moreover, the P-gp function was evaluated by the intracellu-lar accumulation of the P-gp substrate detected by flow cytometry. Results:We found the subcytotoxic doses of LA significantly enhanced adriamycin- or vinc-ristine-induced G2/M arrest and apoptosis. These effects were consistent with the ability of LA to inhibit P-gp function. Moreover, LA dramatically enhanced the verapamil (VER) ability to reverse drug resistance. Conclusion:LA has the poten-tial to be developed as a novel P-gp modulator. Furthermore, the combination of LA and VER might represent a more sufficient but less toxic anti-MDR regimen.

  15. Increased Expression of P-Glycoprotein Is Associated With Chlorpyrifos Resistance in the German Cockroach (Blattodea: Blattellidae).

    Science.gov (United States)

    Hou, Weiyuan; Jiang, Chu; Zhou, Xiaojie; Qian, Kun; Wang, Lei; Shen, Yanhui; Zhao, Yan

    2016-09-15

    A principal method for control of the German cockroach, Blattella germanica (L.), is the broad-spectrum organophosphorus insecticide, chlorpyrifos (O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothioate); however, extensive and repeated application has resulted in the development of resistance to chlorpyrifos in this insect. Evidence suggests that ATP-binding cassette protein transporters, including P-glycoprotein, are involved in insecticide resistance. However, little is known of the role of P-glycoprotein in insecticide resistance in the German cockroach. Here, we developed a chlorpyrifos-resistant strain of German cockroach and investigated the relationship between P-glycoprotein and chlorpyrifos resistance using toxicity assays; inhibition studies with two P-glycoprotein inhibitors, verapamil and quinine; P-glycoprotein-ATPase activity assays; and western blotting analysis. After 23 generations of selection from susceptible strain cockroaches, we obtained animals with high resistance to chlorpyrifos. When P-glycoprotein-ATPase activity was inhibited by verapamil and quinine, we observed enhanced susceptibility to chlorpyrifos in both control and chlorpyrifos-resistant cockroaches. No significant alterations of P-glycoprotein expression or ATPase activity were observed in cockroaches acutely exposed to LD50 doses of chlorpyrifos for 24 h, while P-glycoprotein expression and ATPase activity were clearly elevated in the chlorpyrifos-resistant cockroach strain. Thus, we conclude that P-glycoprotein is associated with chlorpyrifos resistance in the German cockroach and that elevated levels of P-glycoprotein expression and ATPase activity may be an important mechanism of chlorpyrifos resistance in the German cockroach.

  16. Mechanism of flavonoids against P-glycoprotein mediated tumor multidrug resistance:research advances%黄酮类化合物抵抗P-糖蛋白介导肿瘤多药耐药特性机制研究进展

    Institute of Scientific and Technical Information of China (English)

    韩嘉华; 朱斯琦; 谢燕

    2016-01-01

    Multidrug resistance(MDR)is one of the important reasons for the failure of chemotherapy in clinic,whereas the mechanism of MDR is very complicated. At present,it is considered that the efflux protein P-glycoprotein(P-gp)is one of the main factors which can lead to MDR,descreasing the successful rate of chemotherapy because chemotherapeutics with different structures and functions can be effluxed by P-gp. Flavonoids are found in many kinds of plants and have a wide range of pharmacological activi⁃ties. Besides,recent studies have reported that flavonoids can reverse the MDR of tumor and affect the expression and function of ef⁃flux transporter,especially P-gp. In this review,we elucidate the mechanisms of flavonoids reversing tumor MDR mediated by P-gp from the following aspects:inhibition of P-gp protein expression,inhibition of P-gp efflux function,and prevention of combining P-gp and its substrate,etc. The review can provide some ideas and references for the application of flavonoids in tumor therapy.%多药耐药(MDR)的产生是临床上治疗肿瘤失败的重要原因之一,而MDR的相关机制却十分复杂。目前认为P-糖蛋白(P-gp)是介导MDR的主要因素之一,它能将不同结构和功能的化疗药物排出细胞外,明显降低化疗的成功率。黄酮类化合物存在于多种植物中,具有广泛的药理活性,近年研究发现,黄酮类化合物具有逆转肿瘤MDR作用,能影响外排转运蛋白特别是P-gp的表达和功能。本文从黄酮类化合物抑制P-gp蛋白表达的分子机制、抑制P-gp的外排功能、阻止P-gp与底物结合等方面来阐述黄酮成分抵抗P-gp介导肿瘤MDR特性的机制,为黄酮类化合物在肿瘤治疗方面的应用提供思路和借鉴。

  17. Use of P-glycoprotein gene probes to investigate anthelmintic resistance in Haemonchus contortus and comparison with Onchocerca volvulus

    NARCIS (Netherlands)

    Kwa, M.S.G.; Okoli, M.N.; Schulz-Key, H.; Okongkwo, P.O.; Roos, M.H.

    1998-01-01

    A P-glycoprotein gene probe from the sheep parasitic nematode Haemonchus contortus was developed and used to analyse restriction fragment length polymorphisms between susceptible isolates and isolates resistant to either benzimidazole; levamisole and benzimidazole; or benzimidazole, ivermectin and c

  18. Multidrug resistance associated proteins in multidrug resistance

    OpenAIRE

    Sodani, Kamlesh; Patel, Atish; Kathawala, Rishil J.; Chen, Zhe-Sheng

    2012-01-01

    Multidrug resistance proteins (MRPs) are members of the C family of a group of proteins named ATP-binding cassette (ABC) transporters. These ABC transporters together form the largest branch of proteins within the human body. The MRP family comprises of 13 members, of which MRP1 to MRP9 are the major transporters indicated to cause multidrug resistance in tumor cells by extruding anticancer drugs out of the cell. They are mainly lipophilic anionic transporters and are reported to transport fr...

  19. Drug-protein hydrogen bonds govern the inhibition of the ATP hydrolysis of the multidrug transporter P-glycoprotein.

    Science.gov (United States)

    Chufan, Eduardo E; Kapoor, Khyati; Ambudkar, Suresh V

    2016-02-01

    P-glycoprotein (P-gp) is a member of the ATP-binding cassette transporter superfamily. This multidrug transporter utilizes energy from ATP hydrolysis for the efflux of a variety of hydrophobic and amphipathic compounds including anticancer drugs. Most of the substrates and modulators of P-gp stimulate its basal ATPase activity, although some inhibit it. The molecular mechanisms that are in play in either case are unknown. In this report, mutagenesis and molecular modeling studies of P-gp led to the identification of a pair of phenylalanine-tyrosine structural motifs in the transmembrane region that mediate the inhibition of ATP hydrolysis by certain drugs (zosuquidar, elacridar and tariquidar), with high affinity (IC50's ranging from 10 to 30nM). Upon mutation of any of these residues, drugs that inhibit the ATPase activity of P-gp switch to stimulation of the activity. Molecular modeling revealed that the phenylalanine residues F978 and F728 interact with tyrosine residues Y953 and Y310, respectively, in an edge-to-face conformation, which orients the tyrosines in such a way that they establish hydrogen-bond contacts with the inhibitor. Biochemical investigations along with transport studies in intact cells showed that the inhibitors bind at a high affinity site to produce inhibition of ATP hydrolysis and transport function. Upon mutation, they bind at lower affinity sites, stimulating ATP hydrolysis and only poorly inhibiting transport. These results also reveal that screening chemical compounds for their ability to inhibit the basal ATP hydrolysis can be a reliable tool to identify modulators with high affinity for P-gp.

  20. Resistance to paclitaxel in a cisplatin-resistant ovarian cancer cell line is mediated by P-glycoprotein.

    Directory of Open Access Journals (Sweden)

    Britta Stordal

    Full Text Available The IGROVCDDP cisplatin-resistant ovarian cancer cell line is also resistant to paclitaxel and models the resistance phenotype of relapsed ovarian cancer patients after first-line platinum/taxane chemotherapy. A TaqMan low-density array (TLDA was used to characterise the expression of 380 genes associated with chemotherapy resistance in IGROVCDDP cells. Paclitaxel resistance in IGROVCDDP is mediated by gene and protein overexpression of P-glycoprotein and the protein is functionally active. Cisplatin resistance was not reversed by elacridar, confirming that cisplatin is not a P-glycoprotein substrate. Cisplatin resistance in IGROVCDDP is multifactorial and is mediated in part by the glutathione pathway and decreased accumulation of drug. Total cellular glutathione was not increased. However, the enzyme activity of GSR and GGT1 were up-regulated. The cellular localisation of copper transporter CTR1 changed from membrane associated in IGROV-1 to cytoplasmic in IGROVCDDP. This may mediate the previously reported accumulation defect. There was decreased expression of the sodium potassium pump (ATP1A, MRP1 and FBP which all have been previously associated with platinum accumulation defects in platinum-resistant cell lines. Cellular localisation of MRP1 was also altered in IGROVCDDP shifting basolaterally, compared to IGROV-1. BRCA1 was also up-regulated at the gene and protein level. The overexpression of P-glycoprotein in a resistant model developed with cisplatin is unusual. This demonstrates that P-glycoprotein can be up-regulated as a generalised stress response rather than as a specific response to a substrate. Mechanisms characterised in IGROVCDDP cells may be applicable to relapsed ovarian cancer patients treated with frontline platinum/taxane chemotherapy.

  1. Progesterone-adenine hybrids as bivalent inhibitors of P-glycoprotein-mediated multidrug efflux: design, synthesis, characterization and biological evaluation.

    Science.gov (United States)

    Zeinyeh, Waël; Mahiout, Zahia; Radix, Sylvie; Lomberget, Thierry; Dumoulin, Axel; Barret, Roland; Grenot, Catherine; Rocheblave, Luc; Matera, Eva-Laure; Dumontet, Charles; Walchshofer, Nadia

    2012-10-01

    Bivalent ligands were designed on the basis of the described close proximity of the ATP-site and the putative steroid-binding site of P-glycoprotein (ABCB1). The syntheses of 19 progesterone-adenine hybrids are described. Their abilities to inhibit P-glycoprotein-mediated daunorubicin efflux in K562/R7 human leukemic cells overexpressing P-glycoprotein were evaluated versus progesterone. The hybrid with a hexamethylene linker chain showed the best inhibitory potency. The efficiency of these progesterone-adenine hybrids depends on two main factors: (i) the nature of the linker and (ii) its attachment point on the steroid skeleton.

  2. Interaction of multidrug resistance reversal agents with P-glycoprotein ATPase activity on blood-brain barrier%多药耐药逆转剂与血脑屏障上P-糖蛋白ATP酶活性间的相互作用

    Institute of Scientific and Technical Information of China (English)

    何玲; 刘国卿

    2002-01-01

    目的:进一步探讨P-糖蛋白(P-gp)与其多种耐药逆转剂间ATP依赖性相互作用的机制.方法:从牛脑灰质中分离得到微血管内皮细胞(BCEC),制成细胞膜,定磷法测定BCEC膜上P-gp ATPase活性.结果:维拉帕米(Ver)、长春新碱(VCR)、阿霉素(Dox)、粉防己碱(Tet)、蝙蝠葛碱(DRC)、小檗胺(BBM)以及蝙蝠葛苏林碱(DRS)增加基础P-gpATPase活性,其Km值分别约为17、5.9、41、2.3、11、23和22 μmol/L.小檗碱(BBR)仅有轻微的激活作用,延胡索乙素(dl-THP)和左旋四氢巴马汀(l-THP)不改变基础P-gp ATPase活性.环孢素A(CsA)抑制基础P-gp ATPase活性;竞争性抑制Ver或VCR激活的P-gp ATPase活性;非竞争性抑制Dox或Tet激活的P-gp ATPase活性.Dox非竞争性抑制Tet-激活的P-gp ATPase活性.结论:各种多药耐药逆转剂与P-gp相互作用的机制及其对P-gp ATPase活性的影响各不相同.CsA、Ver和VCR在血脑屏障P-gp上的结合部位可能是重叠的或者是有相互联系的,而CsA、Dox和Tet与P-gp的结合是相互独立的,并存在各自不同的结合部位.%AIM: To gain further insights into the mechanism of the ATP-dependent interaction of P-glycoprotein (P-gp) with various multidrug resistance (MDR) reversal agents.METHODS: Bovine brain capillary endothelial cells (BCEC) were isolated from cerebral gray matter using modifications of the mechanical homogenization technique. Plasma membranes were prepared from BCEC.The P-gp adenosine triphosphatase (ATPase) activity of the isolated BCEC membranes was estimated by measuring inorganic phosphate liberation. RESULTS:The basal P-gp ATPase activity was increased by verapamil ( Ver ), vincristine ( VCR ), doxorubicin (Dox), tetrandrine (Tet), dauricine (DRC), berbamine (BBM), and daurisoline (DRS), with respective halfmaximal activity concentrations Km of about 17, 5.9,41, 2.3, 11, 23, and 22 μmol/L. Berberine (BBR)produced a relatively slight activation. dl-Tetrahydropalmatine (dl-THP) and l

  3. Resistant mechanisms of anthracyclines--pirarubicin might partly break through the P-glycoprotein-mediated drug-resistance of human breast cancer tissues.

    Science.gov (United States)

    Kubota, T; Furukawa, T; Tanino, H; Suto, A; Otan, Y; Watanabe, M; Ikeda, T; Kitajima, M

    2001-01-01

    Juliano and Ling initially reported the expression of a 170 kDa glycoprotein in the membrane of Chinese hamster ovarian cells in 1976, and named this glycoprotein P-glycoprotein (P-gp) based on its predicted role of causing "permeability" of the cell membrane. After much research on anthracycline-resistance, this P-gp was finally characterized as a multidrug-resistant protein coded by the mdr1 gene. Multidrug resistance associated protein (MRP) was initially cloned from H69AR, a human small cell-lung carcinoma cell line which is resistant to doxorubicin (DXR) but does not express P-gp. MRP also excretes substrates through the cell membrane using energy from ATP catabolism. The substrate of MRP is conjugated with glutathione before active efflux from cell membrane. Recently, membrane transporter proteins were re-categorized as members of "ATP-Binding Cassette transporter"(ABC-transporter) superfamily, as shown at http://www.med.rug.nl/mdl/humanabc.htm and http://www.gene.ucl.ac.uk/nomenclature/genefamily/abc.html. A total of ABC transporters have been defined, and MDR1 and multidrug resistance associated protein 1 (MRP1) were reclassified as ABCB1 and ABCC1, respectively. Their associated superfamilies include 11 and 13 other protein, in addition to ABCB and ABCC, respectively. Lung resistance-related protein (LRP) is not a member of the superfamily of ABC transporter proteins, because it shows nuclear membrane expression and transports substrate between nucleus and cytoplasm. LRP was initially cloned from a non-small cell lung carcinoma cell line, SW1573/2R120 which is resistant to DXR, vincristine, etoposide and gramicidin D and does not express P-gp. The mechanisms of resistance remains unclear, and why some resistant cell lines express P-gp and others express MRP and/or LRP is likewise unclear.

  4. P-糖蛋白抑制剂HZ08对裸鼠体内肿瘤多药耐药逆转以及对大鼠肝P450酶影响%Effects of HZ08,a novel P-glycoprotein inhibitor, on the reversal of P-glyco-protein mediated multidrug resistance in nude mice and cytochrome P-450 ac-tivities in rat liver microsomes

    Institute of Scientific and Technical Information of China (English)

    严方; 李运曼; 王秋娟; 方伟蓉; 康恺; 张陆勇

    2008-01-01

    目的:考察P-糖蛋白抑制剂HZ08 对K562/ADM接种裸鼠体内肿瘤多药耐药的逆转作用及HZ08对大鼠肝P450酶亚型的影响.方法:K562/ADM接种的裸鼠尾静脉注射HZ08和阿霉素4周,与对照组和阳性药组比较瘤重;HZ08与CYP450亚型特异性底物在大鼠肝微粒体中温孵,与对照组比较测定HZ08 对于CYP450亚型的影响.结果:HZ08可显著减小裸鼠体内的瘤重,并对大鼠肝微粒体CYP3A4有较弱的抑制作用,对其他P450酶亚型无显著抑制作用.结论:HZ08在裸鼠体内具有较好的逆转P-糖蛋白介导的肿瘤多药耐药的作用,并且在体外实验中对P450酶具有较小的影响.%Aim: To evaluate the effects of HZ08, a novel P-glycoprotein inhibitor, on reversing tumor resistance of K562/ADM to adriamycin in nude mice and on the activities of cytochromes P-450 (GYP) isoforms. Methods: Nude mice bearing K562/ADM were injected at different doses of HZ08 with adriamycin for 4 weeks. The tumor weights of HZ08 treatment groups were determined and compared to those of the control and positive groups. In addition, the effects of HZ08 were examined on GYP isoforms-mediated metabolism of specific substrates by GYP isoforms in rat liver microsomes in the presence or absence of HZ08. Results: The tumor weights of HZ08 treatment groups were significantly decreased and HZ08 was a relatively potent inhibitor of CYP3A4, with no significant effects on other isoforms tested. Conclusion: HZ08 has potent effects on reversing P-glycoprotein mediated tumor multidrug resistance in rive with little influence on cytoehrome P-450 activities of rat liver.

  5. Nuclear localization of P-glycoprotein is responsible for protection of the nucleus from doxorubicin in the resistant LoVo cell line.

    Science.gov (United States)

    Szaflarski, Witold; Sujka-Kordowska, Patrycja; Januchowski, Radosław; Wojtowicz, Karolina; Andrzejewska, Małgorzata; Nowicki, Michał; Zabel, Maciej

    2013-07-01

    The high expression of P-glycoprotein (P-gp) belongs to one of the most important factors causing multidrug-resistant (MDR) of cancer cells. P-gp is primarily associated with plasma membrane; however, small fraction of that protein is present in the nuclear envelope. Such phenomenon is observed in cancer cells and may result in the selection of MDR cells as the secondary tumor and/or resistant metastasis that significantly shorten patient survival rate. Here, we confirmed nuclear localization of P-gp in resistant LoVo cells and demonstrated its impact on doxorubicin efflux from the nucleus to cytoplasm. Furthermore, we showed that P-gp located at the nuclear envelope might have a different glycoside chain when compared to the form located in the cytoplasm. It suggests that the glycoside chain plays a role in the intracellular trafficking of P-gp and may decide about the destination place in the cell.

  6. P-glycoprotein-mediated resistance to chemotherapy in cancer cells: using recombinant cytosolic domains to establish structure-function relationships

    Directory of Open Access Journals (Sweden)

    Di Pietro A.

    1999-01-01

    Full Text Available Resistance to chemotherapy in cancer cells is mainly mediated by overexpression of P-glycoprotein (Pgp, a plasma membrane ATP-binding cassette (ABC transporter which extrudes cytotoxic drugs at the expense of ATP hydrolysis. Pgp consists of two homologous halves each containing a transmembrane domain and a cytosolic nucleotide-binding domain (NBD which contains two consensus Walker motifs, A and B, involved in ATP binding and hydrolysis. The protein also contains an S signature characteristic of ABC transporters. The molecular mechanism of Pgp-mediated drug transport is not known. Since the transporter has an extraordinarily broad substrate specificity, its cellular function has been described as a "hydrophobic vacuum cleaner". The limited knowledge about the mechanism of Pgp, partly due to the lack of a high-resolution structure, is well reflected in the failure to efficiently inhibit its activity in cancer cells and thus to reverse multidrug resistance (MDR. In contrast to the difficulties encountered when studying the full-length Pgp, the recombinant NBDs can be obtained in large amounts as soluble proteins. The biochemical and biophysical characterization of recombinant NBDs is shown here to provide a suitable alternative route to establish structure-function relationships. NBDs were shown to bind ATP and analogues as well as potent modulators of MDR, such as hydrophobic steroids, at a region close to the ATP site. Interestingly, flavonoids also bind to NBDs with high affinity. Their binding site partly overlaps both the ATP-binding site and the steroid-interacting region. Therefore flavonoids constitute a new promising class of bifunctional modulators of Pgp.

  7. Temozolomide reverses doxorubicin resistance by inhibiting P-glycoprotein in malignant glioma cells.

    Science.gov (United States)

    Zhang, Rong; Saito, Ryuta; Shibahara, Ichiyo; Sugiyama, Shinichiro; Kanamori, Masayuki; Sonoda, Yukihiko; Tominaga, Teiji

    2016-01-01

    Temozolomide is a standard chemotherapy agent for malignant gliomas, but the efficacy is still not satisfactory. Therefore, combination chemotherapy using temozolomide with other anti-tumor compounds is now under investigation. Here we studied the mechanism of the synergistic anti-tumor effect achieved by temozolomide and doxorubicin, and elucidated the inhibitory effect of temozolomide on P-glycoprotein (P-gp). Temozolomide significantly enhanced sensitivity to P-gp substrate in glioma cells, particularly in P-gp-overexpressed cells. Synergetic effects, as determined by isobologram analysis, were observed by combining temozolomide and doxorubicin. Subsequently, flow cytometry was utilized to assess the intracellular retention of doxorubicin in cells treated with doxorubicin with or without temozolomide. Temozolomide significantly increased the accumulation of doxorubicin in these cells. The P-gp adenosine triphosphatase (ATPase) assay showed that temozolomide inhibited the ATPase activity of P-gp. In addition, temozolomide combined with doxorubicin significantly prolonged the survival of 9L intracranial allografted glioma-bearing rats compared to single agent treatment. Collectively, our findings suggest that temozolomide can reverse doxorubicin resistance by directly affecting P-gp transport activity. Combination chemotherapy using temozolomide with other agents may be effective against gliomas in clinical applications.

  8. 盐酸千金藤碱逆转K562/ADR细胞多药耐药性及其机制%Correlation between reversing effect of cepharanthine hydrochloride on multidrug resistance and P-glycoprotein expression and function of K562/ADR cells

    Institute of Scientific and Technical Information of China (English)

    彭有梅; 王宁; 王亚峰; 韩立; 张艳; 江金花; 周玉冰; 王庆端

    2012-01-01

    研究盐酸千金藤碱(cepharanthine hydrochloride,CH)逆转K562/ADR细胞多药耐药性及其机制.采用MTT法检测多柔比星(adriamycin,ADR)单用及分别与CH、维拉帕米(verapamil,VER)合用的细胞毒作用;采用流式细胞仪,测定CH对细胞内ADR蓄积、罗丹明123 (Rho123)蓄积和泵出及P糖蛋白(P-gp)表达的影响.结果表明,CH(4 μmol·L-1)使K562/ADR细胞对ADR的敏感性增加7.43倍,逆转活性是VER的3.19倍,但对K562敏感株基本无影响.同时CH浓度依赖性地增加K562/ADR细胞内ADR和Rho123的蓄积,减少Rho123的泵出,抑制P糖蛋白的表达,但对K562细胞均无明显影响.CH在体外逆转肿瘤细胞多药耐药性的作用可能与其抑制P糖蛋白的功能和表达有关.%In this study, cepharanthine hydrochloride (CH) was tested for its potential ability to modulate the expression and function of P-glycoprotein (P-gp) in the multidmg-resistant human chronic myelogenous leukemia cell line K562/ADR. Cytotoxicity of adriamycin (ADR) alone or in combination with CH or verapamil (VER) in K562 and K562/ADR cells was determined by MTT assay. Based on flow cytometric technology, the effect of CH or VER on the uptake and efflux of rhodaminel23 (Rhol23) and the accumulation of ADR in these cells was detected by measuring Rhol23 or ADR-associated mean fluorescence intensity (MFI). The effects of CH and VER on P-glycoprotein (P-gp) expression in K562 and K562/ADR cells were also measured using a flow cytometry with PE-conjugated P-glycoprotein antibody. The results show that CH significantly enhanced the sensitivity of K562/ADR cells to ADR, 4 μmol·L"1 of CH enhanced the sensitivity of K562/ADR cells to ADR by 7.43 folds, the reversal activity was 3.19 times higher than that of verapamil. However, CH had no effect on drug-sensitive K562 cells (P < 0.05). CH increased Rhol23 and ADR accumulation in a concentration-dependent manner (2-8 umol·L-1) and inhibited the efflux of Rhol23 from these cells, but

  9. Co-treatment by docetaxel and vinblastine breaks down P-glycoprotein mediated chemo-resistance

    Directory of Open Access Journals (Sweden)

    Mahsa Mohseni

    2016-03-01

    Results: Combination treatment of the cells with docetaxel and vinblastine decreased the IC50 values for docetaxel from (30±3.1 to (15±2.6 nM and for vinblastine from (30±5.9 to (5±5.6 nM (P≤0.05.               P-glycoprotein mRNA expression level showed a significant up-regulation in the cells incubated with each drug alone (P≤0.001. Incubation of the cells with combined concentrations of both agents neutralized P-glycoprotein overexpression (P≤0.05. Adding verapamil, a P-glycoprotein inhibitor caused a further increase in the percentage of apoptotic cells when the cells were treated with both agents.  Conclusion:Our results suggest that combination therapy along with P-glycoprotein inhibition can be considered as a novel approach to improve the efficacy of chemotherapeutics in cancer patients with high P-glycoprotein expression.

  10. Diminished expression of multidrug resistance-associated protein 1 (MRP1) in bronchial epithelium of COPD patients

    NARCIS (Netherlands)

    van der Deen, Margaretha; Marks, Hendrik; Willemse, Brigitte W. M.; Postma, Dirkje S.; Muller, Michael; Smit, Egbert F.; Scheffer, George L.; Scheper, Rik J.; de Vries, Elisabeth G. E.; Timens, Wim

    2006-01-01

    Cigarette smoke is the principal risk factor for chronic obstructive pulmonary disease (COPD). Multidrug resistance proteins, such as multidrug resistance-associated protein-1 (MRP1), P-glycoprotein (P-gp), and lung resistance-related protein (LRP), may protect against oxidative stress and toxic com

  11. Multidrug resistance: Physiological principles and nanomedical solutions.

    Science.gov (United States)

    Kunjachan, Sijumon; Rychlik, Błażej; Storm, Gert; Kiessling, Fabian; Lammers, Twan

    2013-11-01

    Multidrug resistance (MDR) is a pathophysiological phenomenon employed by cancer cells which limits the prolonged and effective use of chemotherapeutic agents. MDR is primarily based on the over-expression of drug efflux pumps in the cellular membrane. Prominent examples of such efflux pumps, which belong to the ATP-binding cassette (ABC) superfamily of proteins, are Pgp (P-glycoprotein) and MRP (multidrug resistance-associated protein), nowadays officially known as ABCB1 and ABCC1. Over the years, several strategies have been evaluated to overcome MDR, based not only on the use of low-molecular-weight MDR modulators, but also on the implementation of 1-100(0) nm-sized drug delivery systems. In the present manuscript, after introducing the most important physiological principles of MDR, we summarize prototypic nanomedical strategies to overcome multidrug resistance, including the use of carrier materials with intrinsic anti-MDR properties, the use of nanomedicines to modify the mode of cellular uptake, and the co-formulation of chemotherapeutic drugs together with low- and high-molecular-weight MDR inhibitors within a single drug delivery system. While certain challenges still need to be overcome before such constructs and concepts can be widely applied in the clinic, the insights obtained and the progress made strongly suggest that nanomedicine formulations hold significant potential for improving the treatment of multidrug-resistant malignancies.

  12. Multidrug resistance associated proteins in multidrug resistance

    Institute of Scientific and Technical Information of China (English)

    Kamlesh Sodani; Atish Patel; Rishil J. Kathawala; Zhe-Sheng Chen

    2012-01-01

    Multidrug resistance proteins (MRPs) are members of the C family of a group of proteins named ATP-binding cassette (ABC) transporters.These ABC transporters together form the largest branch of proteins within the human body.The MRP family comprises of 13 members,of which MRP1 to MRP9 are the major transporters indicated to cause multidrug resistance in tumor cells by extruding anticancer drugs out of the cell.They are mainly lipophilic anionic transporters and are reported to transport free or conjugates of glutathione (GSH),glucuronate,or sulphate.In addition,MRP1 to MRP3 can transport neutral organic drugs in free form in the presence of free GSH.Collectively,MRPs can transport drugs that differ structurally and mechanistically,including natural anticancer drugs,nucleoside analogs,antimetabolites,and tyrosine kinase inhibitors.Many of these MRPs transport physiologically important anions such as leukotriene C4,bilirubin glucuronide,and cyclic nucleotides.This review focuses mainly on the physiological functions,cellular resistance characteristics,and probable in vivo role of MRP1 to MRP9.

  13. Effects of multidrug resistance, antisense RNA on the chemosensitivity of hepatocellular carcinoma cells

    Institute of Scientific and Technical Information of China (English)

    Bo Li; Jian-Ping Gong; Tian Ye; Lei Zhao; De-Hua Li; Xing-Hua Gou; Lan-Ying Zhao; Lei Han; Lin Chen; Lu-Nan Yan

    2006-01-01

    BACKGROUND: Multidrug resistance is a major obstacle in cancer chemotherapy. We examined whether the antisense RNA of multidrug resistance gene 1 (mdr1) could reverse multidrug resistance in the human hepatocellular carcinoma (HCC) cell line SMMC7721/ADM. METHODS: The recombinant adenoviruses pAdEasy-GFP-ASmdr1 product was produced by the adenoviral vector AdEasy system, which can express antisense RNA against the mdr1 gene. Following that, the recombinant adenovirus was transfected into the P-glycoprotein-producing multidrug resistance cell line, SMMC7721/ADM human HCC cells resistant to adriamycin (ADM) and daunorubicin (DNR). In order to investigate the reversal of multidrug resistance phenotype, we measured the expression of mdr1 mRNA by RT-PCR and the production of P-glycoprotein by lfow cytometry. The sensitivities for ADM and DNR SMMC7721/ADM cells were examined by [3-(4, 5-dimethylthi-azol-2-yl)-2,5 diphenyl-terazolium bromide] (MTT) analysis. RESULTS: The low-level expression of mdr1 mRNA and P-glycoprotein production were observed in parental sensitive cells SMMC/7721 in addition to the overexpression of mdr1 mRNA and P-glycoprotein in SMMC7721/ADM cells. The transfection of antisense-RNA into SMMC7721/ADM cells resulted in decreases of mdr1 mRNA and P-glycoprotein, but increase of drug sensitivities. The sensitivities of transfected SMMC7721/ADM cells to ADM and DNR in IC50 reduced by 31.25% and 62.96%respectively. CONCLUSIONS: Mdr1 antisense RNA can increase the sensitivities of SMMC7721/ADM cells to anticancer drug by decreasing the expression of the mdr1 gene and inhibiting P-glycoprotein expression. This strategy may be applicable to cancer patients with P-glycoportein mediated multidrug resistance.

  14. Expression and cellular distribution of multidrug resistance-related proteins in the hippocampus of patients with mesial temporal lobe epilepsy

    NARCIS (Netherlands)

    E. Aronica; J.A. Gorter; M. Ramkema; S. Redeker; F. Ozbas-Gercer; E.A. van Vliet; G.L. Scheffer; R.J. Scheper; P. van der Valk; J.C. Baayen; D. Troost

    2004-01-01

    Purpose: This study investigated the cellular distribution of different multidrug resistance (MDR)-related proteins such as P-glycoprotein (P-gp), the multidrug resistance-associated proteins (MRP) 1 and 2, and the major vault protein (MVP) in normal and sclerotic hippocampus of patients with medica

  15. Medicated serum prepared with Chinese herbal medicine Zhizhen Recipe down-regulates activity of nuclear factor-KB and expression of P-glycoprotein in human colorectal cancer multidrug-resistant cell line HCT-8/VCR%至真方含药血清对人大肠癌多药耐药细胞HCT-8/VCR内核因子κB活性及P-糖蛋白表达与功能的抑制作用

    Institute of Scientific and Technical Information of China (English)

    蔡松柏; 张旭; 陈志霞; 孔令春; 王松坡

    2011-01-01

    To investigate the effects of medicated serum prepared with Chinese herbal medicine Zhizhen Recipe (ZZR) on activity of nuclear factor-kB (NF-kB) and expression and function of P-glycoprotein (P-gp) in human colorectal cancer multidrug-resistant cell line HCT-8/VCR.Methods: The multidrug resistance of HCT-8/VCR cells was detected by cell counting kit-8 method, and the experimental concentrations of ZZR-medicated serum were determined by the same way. HCT-8 and HCT-8/ VCR cells were treated with ZZR-medicated serum of medium dose for 24 h. The activity of NF-kB was determined by enzyme-linked immunosorbent assay. The intracellular distribution of P-gp was detected by laser scanning confocal microscopy, and the mean fluorescence intensity of rhodamine 123 was detected by flow cytometry.Results: ZZR-medicated sera with volume fraction of 8% , 16% and 32% of medium dose were confirmed as the experimental sera. Compared with the untreated group, NF-kB activities of the ZZR-medicated serum groups (ZZR-medicated serum with volume fraction of 8%, 16% and 32% of medium dose) were obviously down-regulated (P<0. 01), which had a negative correlation with the concentrations. After interfering HCT-8/VCR with ZZR-medicated serum of different concentrations for 24 h, P-gp in HCT-8/VCR transmitted gradually from cell membrane to cytoplasm and nuclei. Nuclei became pyknotic and cracking. Compared with the untreated group, the mean fluorescence intensities of ZZR-medicated serum groups declined with concentration gradients (P<0. 01). The efflux of intracellular rhodamine 123 decreased, the wave crest shifted to right, and the intracellular fluorescence intensity strengthened (P<0.01). Conclusion: ZZR-medicated sera of experimental concentrations down-regulate activity of NF-KB and expression and function of P-gp in human colorectal cancer multidrug-resistant cell line HCT-8/VCR and the effect is related to the concentrations.%目的:探讨至真方是

  16. ANALYSIS OF THE EXPRESSION OF MRP, THE GENE FOR A NEW PUTATIVE TRANSMEMBRANE DRUG TRANSPORTER, IN HUMAN MULTIDRUG RESISTANT LUNG-CANCER CELL-LINES

    NARCIS (Netherlands)

    ZAMAN, GJR; VERSANTVOORT, CHM; SMIT, JJM; EIJDEMS, EWHM; DEHAAS, M; SMITH, AJ; BROXTERMAN, HJ; MULDER, NH; DEVRIES, EGE; BAAS, F; BORST, P

    1993-01-01

    Human cells can become multidrug resistant (MDR) by an increase in the activity of the MDR1 P-glycoprotein or by other, as vet unknown mechanisms, referred to as non-P-glycoprotein mediated MDR (non-Pgp MDR). S. P. C. Cole et al. [Science (Washington DC), 258: 1650-1654, 1992] recently reported that

  17. MDR3 P-glycoprotein, a phosphatidylcholine translocase, transports several cytotoxic drugs and directly interacts with drags as judged by interference with nucleotide trapping

    NARCIS (Netherlands)

    Smith, A.J.; van Helvoort, A.; van Meer, G.; Szabó, K.; Welker, E.; Szakács, G.; Váradi, A.; Sarkadi, B.; Borst, P.

    2000-01-01

    The human MDR3 gene is a member of the multidrug resistance (MDR) gene family. The MDR3 P-glycoprotein is a transmembrane protein that translocates phosphatidylcholine. The MDR1 P-glycoprotein related transports cytotoxic drugs. Its overexpression can make cells resistant to a variety of drugs. Atte

  18. Multidrug-Resistant Tuberculosis

    Centers for Disease Control (CDC) Podcasts

    2008-10-28

    In this podcast, Dr. Oeltmann discusses multidrug-resistant tuberculosis. An outbreak occurred in Thailand, which led to 45 cases in the U.S. This serious illness can take up to 2 years to treat. MDR TB is a real threat and a serious condition.  Created: 10/28/2008 by Emerging Infectious Diseases.   Date Released: 10/28/2008.

  19. ANTIPSYCHOTICS REVERSE P-GLYCOPROTEIN-MEDIATED DOXORUBICIN RESISTANCE IN HUMAN UTERINE SARCOMA MES-SA/Dx5 CELLS: A NOVEL APPROACH TO CANCER CHEMOTHERAPY.

    Science.gov (United States)

    Angelini, A; Ciofani, G; Conti, P

    2015-01-01

    Multidrug resistance (MDR) mediated by P-glycoprotein (Pgp) remains one of the major obstacles to effective cancer chemotherapy. Several chemosensitizers have been used in vivo and in vitro to reverse MDR but have exhibited several unwanted side effects. Antipsychotics are often administered to treat psychiatric disorders such as delirium, anxiety and sleep disorders in cancer patients during chemotherapy. The present in vitro study, examined the effects of two common antipsychotic compounds, haloperidol and risperidone, and a natural compound such as theobromine on reversing MDR Pgp-mediated, to evaluate their potential use as chemosensitizing agents. The human doxorubicin (doxo) resistant uterine sarcoma cells (MES-SA/Dx5) that overexpress Pgp (100-fold), were treated with the antipsychotic alone (1, 10 and 20 μM) or in combination with different concentrations of doxo (2, 4 and 8 μM). The accumulation and cytotoxicity of doxo (MTT assay) and cellular GSH content (GSH assay) in comparison with verapamil, a well-known Pgp inhibitor, used as reference molecule were examined. It was found that the three compounds significantly enhanced the intracellular accumulation of doxo in resistant cancer cells, when compared with cells receiving doxo alone (p 30%) in resistant cells, when compared to untreated control cells (peffective Pgp inhibitor with the lowest toxicity.

  20. THE ROLE OF P-GLYCOPROTEIN IN RATIONAL PHARMACOTHERAPY IN CARDIOLOGY

    Directory of Open Access Journals (Sweden)

    A. V. Shulkin

    2015-09-01

    Full Text Available On the basis of the analysis of published data the role of P-glycoprotein, carrier protein, in rational pharmacotherapy in cardiology was shown on the example of its substrates – digoxin, antiplatelet agents and anticoagulants. Determination of C3435T polymorphism of multidrug resistance gene (MDR1, encoding P-glycoprotein, in pharmacotherapy with digoxin, antiplatelet drugs (clopidogrel tikagrelol, prasugrel and anticoagulants (dabigatran etexilate, rivaroxaban, edoxaban is not feasible in routine practice. Drug in- teractions have clinical implications for the efficacy and safety of pharmacotherapy in coadministration of these drugs with P-glycoprotein substrates, inducers and inhibitors.

  1. THE ROLE OF P-GLYCOPROTEIN IN RATIONAL PHARMACOTHERAPY IN CARDIOLOGY

    Directory of Open Access Journals (Sweden)

    A. V. Shulkin

    2013-01-01

    Full Text Available On the basis of the analysis of published data the role of P-glycoprotein, carrier protein, in rational pharmacotherapy in cardiology was shown on the example of its substrates – digoxin, antiplatelet agents and anticoagulants. Determination of C3435T polymorphism of multidrug resistance gene (MDR1, encoding P-glycoprotein, in pharmacotherapy with digoxin, antiplatelet drugs (clopidogrel tikagrelol, prasugrel and anticoagulants (dabigatran etexilate, rivaroxaban, edoxaban is not feasible in routine practice. Drug in- teractions have clinical implications for the efficacy and safety of pharmacotherapy in coadministration of these drugs with P-glycoprotein substrates, inducers and inhibitors.

  2. The effect of the plasticizer diethylhexyl phthalate on transport activity and expression of P-glycoprotein in parental and doxo-resistant human sarcoma cell lines.

    Science.gov (United States)

    Angelini, A; Centurione, L; Sancilio, S; Castellani, M L; Conti, P; Di Ilio, C; Porreca, E; Cuccurullo, F; Di Pietro, R

    2011-01-01

    Multidrug resistance (MDR) to cancer therapy is frequently associated with the over-expression of the multidrug transporter MDR1 gene product P-glycoprotein (Pgp) in several types of human tumours. Various chemosensitizers have been used to inhibit Pgp activity but toxicity limits their clinical application. Di(2-ethylhexyl)phthalate (DEHP) is a plasticizer that is released from polyvinyl chloride (PVC) medical devices. Therefore, cancer patients undertaking chemotherapy are exposed to a clinically important amount of DEHP through blood and blood component transfusions, apheresis products, intravenous chemotherapy, parenteral nutrition and other medical treatments. The present study was designed to investigate the effects of DEHP on transport activity and expression of Pgp in order to evaluate its potential use as a chemosensitizer in cancer therapy. Human doxorubicin (doxo) resistant sarcoma cells (MES-SA/Dx5) that over-express Pgp were treated with different doses of doxo (2, 4 and 8 μM) in the presence or absence of various concentrations of DEHP (3, 6 and 12 μM) that were clinically achievable in vivo. Our results show that co-treatment with 2, 4 and 8 μM doxo in the presence of the lowest concentration of DEHP (3 μM) enhanced significantly doxo accumulation in MES-SA/Dx5 cells and, consistently increased the sensitivity to doxo, when compared to controls receiving only doxo. In contrast, higher DEHP concentrations (6 and 12 μM) induced MES-SA/Dx5 to extrude doxo decreasing doxo cytotoxicity toward resistant cells below control values. These results are consistent with the increase in Pgp expression levels in parental MES-SA cells treated with 3, 6 and 12 μM DEHP for 24 h and compared to untreated controls. All in all, these findings suggest a potential clinical application of DEHP as a chemosensitizer to improve effectiveness of the antineoplastic drugs in MDR human tumours.

  3. Expression of Survivin Gene and Its Relationship with Clinical Multidrug Resistance in Osteosarcoma

    Institute of Scientific and Technical Information of China (English)

    NIETao; DAIMin; ZONGShizhang

    2005-01-01

    Objective: To study the expression of survivin and its relationship with clinical multidrug resistance in osteosarcoma. Methods: By using immunohistochemistry (S-P) method, the expression of Survivin in osteosarcoma, osteochondroma and normal osseous tissue, and the expression of P-glycoprotein in osteosarcoma was detected. Results: Survivin positive expression rate was 65.71% in osteosarcoma, but no expression of Survivin was detectable in osteochondroma and normal osseous tissue. The positive expression rate of Survivin was significantly associated with Enneking clinical stages and histological typing (WHO), but no relationship was found among Survivin expression and age, sex and tumor location. The positive expression rate of P-glycoprotein was 45.71%. There was a significant correlation between Survivin and p-glycoprotein. Conclusion: Survivin overexpression was significantly associated with clinical multidrug resistance in osteosarcoma. It could be a potential target for treatment of osteosarcoma.

  4. Guggulsterone of Commiphora mukul resin reverses drug resistance in imatinib-resistant leukemic cells by inhibiting cyclooxygenase-2 and P-glycoprotein.

    Science.gov (United States)

    Xu, Hong-Bin; Xu, Lu-Zhong; Mao, Xia-Ping; Fu, Jun

    2014-06-15

    The purpose of this study was to investigate the effects of guggulsterone on cyclooxygenase-2 and P-glycoprotein mediated drug resistance in imatinib-resistant K562 cells (K562/IMA). MTT cytotoxicity assay, flow cytometry, western blot analysis, and ELISA were performed to investigate the anti-proliferative effect, the reversal action of drug resistance, and the inhibitory effect on cyclooxygenase-2, P-glycoprotein, BCR/ABL kinase, and PGE2 release in K562/IMA cells by guggulsterone. The results showed that co-administration of guggulsterone resulted in a significant increase in chemo-sensitivity of K562/IMA cells to imatinib, compared with imatinib treatment alone. Rhodamine123 accumulation in K562/IMA cells was significantly enhanced after incubation with guggulsterone (60, 120 μM), compared with untreated K562/IMA cells (pP-glycoprotein and prostaglandin E2. However, guggulsterone had little inhibitory effect on the activity of BCR/ABL kinase. The present study indicates guggulsterone induces apoptosis by inhibiting cyclooxygenase-2 and down-regulating P-glycoprotein expression in K562/IMA cells.

  5. Prolonged weightlessness affects promyelocytic multidrug resistance.

    Science.gov (United States)

    Piepmeier, E H; Kalns, J E; McIntyre, K M; Lewis, M L

    1997-12-15

    An immortalized promyelocytic cell line was studied to detect how doxorubicin uptake is affected by microgravity. The purpose of this experiment was to identify the effect that microgravity may have on multidrug resistance in leukocytes. HL60 cells and HL60 cells resistant to anthracycline (HL60/AR) were grown in RPMI and 10% FBS. Upon reaching orbit in the Space Shuttle Endeavour, the cells were robotically mixed with doxorubicin. Three days after mixing, cells were fixed with paraformaldehyde/glutaraldehyde. Ground control experiments were conducted concurrently using a robot identical to the one used on the Shuttle. Fixed cells were analyzed within 2 weeks of launch. Confocal micrographs identified changes in cell structure (transmittance), drug distribution (fluorescence), and microtubule polymerization (fluorescence). Flight cells showed a lack of cytoskeletal polymerization resulting in an overall amorphic globular shape. Doxorubicin distribution in ground cells included a large numbers of vesicles relative to flight cells. There was a greater amount of doxorubicin present in flight cells (85% +/- 9.7) than in ground control cells (43% +/- 26) as determined by image analysis. Differences in microtubule formation between flight cells and ground cells could be partially responsible for the differences in drug distribution. Cytoskeletal interactions are critical to the function of P-glycoprotein as a drug efflux pump responsible for multidrug resistance.

  6. Inhibition of rhodamine 123 secretion by cyclosporin A as a model of P-glycoprotein mediated transport in liver.

    Science.gov (United States)

    Stapf, V; Thalhammer, T; Huber-Huber, R; Felberbauer, F; Gajdzik, L; Graf, J

    1994-01-01

    The interaction between P-glycoprotein modulators and P-glycoprotein mediated transport was investigated using rhodamine 123 in the isolated perfused rat liver of a mutant (TR-) rat strain. TR- rats, deficient in the canalicular multispecific anion transport system, are unable to extrude organic anions (glucuronides) and therefore excrete solely unconjugated rhodamine 123 via P-glycoprotein. Cyclosporin A, a modulator of multidrug resistance in tumor cells, inhibited the biliary secretion of rhodamine 123 dose dependently in a non-competitive manner. Both cyclosporin A and rhodamine inhibited photoaffinity labeling of immunoprecipitated P-glycoprotein with azidopine, indicating binding to hepatic P-glycoprotein. Our results indicate that monitoring the biliary rhodamine 123 secretion in the isolated perfused liver of TR- rats offers a new system for testing modulators of P-glycoprotein like cyclosporin A.

  7. Synthesis of 5-oxyquinoline derivatives for reversal of multidrug resistance

    Directory of Open Access Journals (Sweden)

    Torsten Dittrich

    2012-10-01

    Full Text Available The inhibition of ABC (ATP binding cassette transporters is considered a powerful tool to reverse multidrug resistance. Zosuquidar featuring a difluorocyclopropyl-annulated dibenzosuberyl moiety has been found to be an inhibitor of the P-glycoprotein, one of the best-studied multidrug efflux pumps. Twelve 5-oxyisoquinoline derivatives, which are analogues of zosuquidar wherein the dibenzosuberyl-piperazine moiety is replaced by either a diarylaminopiperidine or a piperidone-derived acetal or thioacetal group, have been synthesized as pure enantiomers. Their inhibitory power has been evaluated for the bacterial multidrug-resistance ABC transporter LmrCD and fungal Pdr5. Four of the newly synthesized compounds reduced the transport activity to a higher degree than zosuquidar, being up to fourfold more efficient than the lead compound in the case of LmrCD and about two times better for Pdr5.

  8. Interactions of retinoids with the ABC transporters P-glycoprotein and Breast Cancer Resistance Protein

    Science.gov (United States)

    Tarapcsák, Szabolcs; Szalóki, Gábor; Telbisz, Ágnes; Gyöngy, Zsuzsanna; Matúz, Krisztina; Csősz, Éva; Nagy, Péter; Holb, Imre J.; Rühl, Ralph; Nagy, László; Szabó, Gábor; Goda, Katalin

    2017-01-01

    Retinoids – derivatives of vitamin A – are important cell permeant signaling molecules that regulate gene expression through activation of nuclear receptors. P-glycoprotein (Pgp) and ABCG2 are plasma membrane efflux transporters affecting the tissue distribution of numerous structurally unrelated lipophilic compounds. In the present work we aimed to study the interaction of the above ABC transporters with retinoid derivatives. We have found that 13-cis-retinoic acid, retinol and retinyl-acetate inhibited the Pgp and ABCG2 mediated substrate transport as well as the substrate stimulated ATPase activity of these transporters. Interestingly, 9-cis-retinoic acid and ATRA (all-trans retinoic acid), both are stereoisomers of 13-cis-retinoic acid, did not have any effect on the transporters’ activity. Our fluorescence anisotropy measurements revealed that 13-cis-retinoic acid, retinol and retinyl-acetate selectively increase the viscosity and packing density of the membrane. Thus, the mixed-type inhibition of both transporters by retinol and ABCG2 by 13-cis-retinoic acid may be the collective result of direct interactions of these retinoids with the substrate binding site(s) and of indirect interactions mediated by their membrane rigidifying effects. PMID:28145501

  9. Mitochondrial P-glycoprotein ATPase contributes to insecticide resistance in the cotton bollworm, Helicoverpa armigera (Noctuidae: Lepidoptera).

    Science.gov (United States)

    Akbar, S Md; Aurade, Ravindra M; Sharma, H C; Sreeramulu, K

    2014-09-01

    Cotton bollworm, Helicoverpa armigera, is one of the most damaging polyphagous pests worldwide, which has developed high levels of resistance to commonly applied insecticides. Mitochondrial P-glycoprotein (Pgp) was detected in the insecticide-resistant strain of H. armigera using C219 antibodies, and its possible role was demonstrated in the efflux of xenobiotic compounds using spectrofluorometer. The TMR accumulated in mitochondria in the absence of ATP, and effluxed out in presence of ATP; the process of efflux was inhibited in the presence of ortho-vandate, an inhibitor of Pgp, in insecticide-resistant larvae of H. armigera. The mitochondria isolated from insecticide-resistant larvae were resistant to insecticide-induced inhibition of oxygen consumption and cytochrome c release. Membrane potential decreased in a dose-dependent manner in the presence of higher concentration of insecticides (>50 µM) in mitochondria of insecticide-resistant larvae. In conclusion, mitochondrial Pgp ATPase detected in the insecticide-resistant larvae influenced the efflux of xenobiotic compounds. Pgp might be involved in protecting the mitochondrial DNA and the components of the electron transport chain from damage due to insecticides, and contributing to the resistance to the deleterious effects of insecticides on the growth of insecticide-resistant H. armigera larvae.

  10. Characterisation of multidrug-resistant Ehrlich ascites tumour cells selected in vivo for resistance to etoposide

    DEFF Research Database (Denmark)

    Nielsen, D; Maare, C; Eriksen, J;

    2000-01-01

    -extractable immunoreactive topoisomerase IIalpha and beta in EHR2/VP16 was reduced by 30-40% relative to that in EHR2. The multidrug resistance-associated protein (MRP) mRNA was increased 20-fold in EHR2/VP16 as compared with EHR2, whereas the expression of P-glycoprotein was unchanged. In EHR2/VP16, the steady-state...

  11. Multidrug-resistant tuberculosis

    Directory of Open Access Journals (Sweden)

    McNerney Ruth

    2008-01-01

    Full Text Available Abstract Background With almost 9 million new cases each year, tuberculosis remains one of the most feared diseases on the planet. Led by the STOP-TB Partnership and WHO, recent efforts to combat the disease have made considerable progress in a number of countries. However, the emergence of mutated strains of Mycobacterium tuberculosis that are resistant to the major anti-tuberculosis drugs poses a deadly threat to control efforts. Multidrug-resistant tuberculosis (MDR-TB has been reported in all regions of the world. More recently, extensively drug resistant-tuberculosis (XDR-TB that is also resistant to second line drugs has emerged in a number of countries. To ensure that adequate resources are allocated to prevent the emergence and spread of drug resistance it is important to understand the scale of the problem. In this article we propose that current methods of describing the epidemiology of drug resistant tuberculosis are not adequate for this purpose and argue for the inclusion of population based statistics in global surveillance data. Discussion Whereas the prevalence of tuberculosis is presented as the proportion of individuals within a defined population having disease, the prevalence of drug resistant tuberculosis is usually presented as the proportion of tuberculosis cases exhibiting resistance to anti-tuberculosis drugs. Global surveillance activities have identified countries in Eastern Europe, the former Soviet Union and regions of China as having a high proportion of MDR-TB cases and international commentary has focused primarily on the urgent need to improve control in these settings. Other regions, such as sub-Saharan Africa have been observed as having a low proportion of drug resistant cases. However, if one considers the incidence of new tuberculosis cases with drug resistant disease in terms of the population then countries of sub-Saharan Africa have amongst the highest rates of transmitted MDR-TB in the world. We propose

  12. A P-Glycoprotein Is Linked to Resistance to the Bacillus thuringiensis Cry3Aa Toxin in a Leaf Beetle

    Directory of Open Access Journals (Sweden)

    Yannick Pauchet

    2016-12-01

    Full Text Available Chrysomela tremula is a polyvoltine oligophagous leaf beetle responsible for massive attacks on poplar trees. This beetle is an important model for understanding mechanisms of resistance to Bacillus thuringiensis (Bt insecticidal toxins, because a resistant C. tremula strain has been found that can survive and reproduce on transgenic poplar trees expressing high levels of the Cry3Aa Bt toxin. Resistance to Cry3Aa in this strain is recessive and is controlled by a single autosomal locus. We used a larval midgut transcriptome for C. tremula to search for candidate resistance genes. We discovered a mutation in an ABC protein, member of the B subfamily homologous to P-glycoprotein, which is genetically linked to Cry3Aa resistance in C. tremula. Cultured insect cells heterologously expressing this ABC protein swell and lyse when incubated with Cry3Aa toxin. In light of previous findings in Lepidoptera implicating A subfamily ABC proteins as receptors for Cry2A toxins and C subfamily proteins as receptors for Cry1A and Cry1C toxins, this result suggests that ABC proteins may be targets of insecticidal three-domain Bt toxins in Coleoptera as well.

  13. A P-Glycoprotein Is Linked to Resistance to the Bacillus thuringiensis Cry3Aa Toxin in a Leaf Beetle

    Science.gov (United States)

    Pauchet, Yannick; Bretschneider, Anne; Augustin, Sylvie; Heckel, David G.

    2016-01-01

    Chrysomela tremula is a polyvoltine oligophagous leaf beetle responsible for massive attacks on poplar trees. This beetle is an important model for understanding mechanisms of resistance to Bacillus thuringiensis (Bt) insecticidal toxins, because a resistant C. tremula strain has been found that can survive and reproduce on transgenic poplar trees expressing high levels of the Cry3Aa Bt toxin. Resistance to Cry3Aa in this strain is recessive and is controlled by a single autosomal locus. We used a larval midgut transcriptome for C. tremula to search for candidate resistance genes. We discovered a mutation in an ABC protein, member of the B subfamily homologous to P-glycoprotein, which is genetically linked to Cry3Aa resistance in C. tremula. Cultured insect cells heterologously expressing this ABC protein swell and lyse when incubated with Cry3Aa toxin. In light of previous findings in Lepidoptera implicating A subfamily ABC proteins as receptors for Cry2A toxins and C subfamily proteins as receptors for Cry1A and Cry1C toxins, this result suggests that ABC proteins may be targets of insecticidal three-domain Bt toxins in Coleoptera as well. PMID:27929397

  14. Amurensin G, a potent natural SIRT1 inhibitor, rescues doxorubicin responsiveness via down-regulation of multidrug resistance 1

    DEFF Research Database (Denmark)

    Oh, Won Keun; Cho, Kyoung Bin; Hien, Tran Thi

    2010-01-01

    The transition from a chemotherapy-responsive cancer to a chemotherapy-resistant one is accompanied by increased expression of multidrug resistance 1 (MDR1, p-glycoprotein), which plays an important role in the efflux from the target cell of many anticancer agents. We recently showed that a Forkh...

  15. Bile canalicular cationic dye secretion as a model for P-glycoprotein mediated transport.

    Science.gov (United States)

    Thalhammer, T; Stapf, V; Gajdzik, L; Graf, J

    1994-04-01

    This study explores properties of P-glycoprotein dependent membrane transport in rat liver with the use of acridine orange as the substrate. We studied the biliary secretion of the dye, its binding to canalicular membrane P-glycoprotein, and effects of the inhibitor cyclosporin A: acridine orange is excreted into bile together with less hydrophobic and glucuronidated metabolites. Cyclosporin A inhibited both the secretion of acridine orange and of its metabolites. In TR- animals, a rat strain that is deficient of the canalicular multi-specific organic anion transport system, non-metabolized acridine orange is the predominant species in bile and its secretion is also inhibited by cyclosporin A. Binding of acridine orange to liver P-glycoprotein was analyzed by photoaffinity labeling with azidopine, a substrate of P-glycoprotein dependent transport in multi-drug resistant tumor cells. Labeling of the immunoprecipitated P-glycoprotein was inhibited by acridine orange, verapamil, and by cyclosporin A. The results show that biliary secretion of acridine orange is highly analogous to P-glycoprotein mediated membrane drug transport in tumor cells that exhibit multi-drug resistance.

  16. Acetylcholine receptor subunit and P-glycoprotein transcription patterns in levamisole-susceptible and -resistant Haemonchus contortus

    Science.gov (United States)

    Sarai, Ranbir S.; Kopp, Steven R.; Coleman, Glen T.; Kotze, Andrew C.

    2013-01-01

    The mechanism of resistance to the anthelmintic levamisole in parasitic nematodes is poorly understood, although there is some evidence implicating changes in expression of nicotinic acetylcholine receptor (nAChR) subunit genes. Hence, in order to define levamisole resistance mechanisms in some Australian field-derived isolates of Haemonchus contortus we examined gene expression patterns and SNPs in nAChR subunit genes, as well as expression levels for P-glycoprotein (P-gp) and receptor ancillary protein genes, in various life stages of one levamisole-sensitive and three levamisole-resistant isolates of this species. Larvae of two isolates showed high-level resistance to levamisole (resistance ratios at the IC50 > 600) while the third isolate showed a degree of heterogeneity, with a resistance factor of only 1.1-fold at the IC50 alongside the presence of a resistant subpopulation. Transcription patterns for nAChR subunit genes showed a great degree of variability across the different life stages and isolates. The most consistent observation was the down-regulation of Hco-unc-63a in adults of all resistant isolates. Transcription of this gene was also reduced in the L3 stage of the two most resistant isolates, highlighting its potential as a resistance marker in the readily accessible free-living stages. There was down regulation of all four Hco-unc-29 paralogs in adults of one resistant isolate. There were no consistent changes in expression of P-gps or ancillary protein genes across the resistant isolates. The present study has demonstrated a complex pattern of nAChR subunit gene expression in H. contortus, and has highlighted several instances where reduced expression of subunit genes (Hco-unc-63a, Hco-unc-29) may be associated with the observed levamisole resistance. The data also suggests that it will be difficult to detect resistance using gene transcription-based methods on pooled larval samples from isolates containing only a resistant subpopulation due to

  17. Human intestinal P-glycoprotein activity estimated by the model substrate digoxin

    DEFF Research Database (Denmark)

    Larsen, U L; Hyldahl Olesen, L; Nyvold, Charlotte Guldborg;

    2007-01-01

    P-glycoprotein (Pgp) plays a part in the intestinal uptake of xenobiotics and has been associated with susceptibility to ulcerative colitis. The aim of this study was to examine Pgp activity in relation to age, gender, medical treatment (rifampicin or ketoconazole) and the multidrug resistance (M...

  18. Multidrug-Resistant TB

    Science.gov (United States)

    Cox, Helen; Coomans, Fons

    2016-01-01

    Abstract The right to enjoy the benefits of scientific progress (REBSP) is a little-known but potentially valuable right that can contribute to rights-based approaches to addressing multidrug-resistant TB (MDR-TB). We argue that better understanding of the REBSP may help to advance legal and civil society action for health rights. While the REBSP does not provide an individual entitlement to have a new drug developed for MDR-TB, it sets up entitlements to expect a state to establish a legislative and policy framework aimed at developing scientific capacity to address the most important health issues and at disseminating the outcomes of scientific research. By making scientific findings available and accessible, people can be enabled to claim the use of science for social benefits. Inasmuch as the market fails to address neglected diseases such as MDR-TB, the REBSP provides a potential counterbalance to frame a positive obligation on states to both marshal their own resources and to coordinate the actions of multiple other actors towards this goal, including non-state actors. While the latter do not hold the same level of accountability as states, the REBSP can still enable the recognition of obligations at a level of “soft law” responsibilities.

  19. Signaling to P-glycoprotein-A new therapeutic target to treat drug-resistant epilepsy?

    NARCIS (Netherlands)

    Hartz, A.M.; Notenboom, S.; Bauer, B.

    2009-01-01

    Epilepsy affects more than 60 million people worldwide. While most patients can be treated with antiepileptic drugs, up to 40% of patients respond poorly to pharmacotherapy. This drug resistance is not well understood and presents a major clinical problem. In this short review we provide background

  20. Multidrug resistance in tumour cells: characterisation of the multidrug resistant cell line K562-Lucena 1

    Directory of Open Access Journals (Sweden)

    VIVIAN M. RUMJANEK

    2001-03-01

    Full Text Available Multidrug resistance to chemotherapy is a major obstacle in the treatment of cancer patients. The best characterised mechanism responsible for multidrug resistance involves the expression of the MDR-1 gene product, P-glycoprotein. However, the resistance process is multifactorial. Studies of multidrug resistance mechanisms have relied on the analysis of cancer cell lines that have been selected and present cross-reactivity to a broad range of anticancer agents. This work characterises a multidrug resistant cell line, originally selected for resistance to the Vinca alkaloid vincristine and derived from the human erythroleukaemia cell K562. This cell line, named Lucena 1, overexpresses P-glycoprotein and have its resistance reversed by the chemosensitisers verapamil, trifluoperazine and cyclosporins A, D and G. Furthermore, we demonstrated that methylene blue was capable of partially reversing the resistance in this cell line. On the contrary, the use of 5-fluorouracil increased the resistance of Lucena 1. In addition to chemotherapics, Lucena 1 cells were resistant to ultraviolet A radiation and hydrogen peroxide and failed to mobilise intracellular calcium when thapsigargin was used. Changes in the cytoskeleton of this cell line were also observed.A resistência a múltiplos fármacos é o principal obstáculo no tratamento de pacientes com câncer. O mecanismo responsável pela resistência múltipla mais bem caracterizado envolve a expressão do produto do gene MDR-1, a glicoproteína P. Entretanto, o processo de resistência tem fatores múltiplos. Estudos de mecanismos de resistência m��ltipla a fármacos têm dependido da análise de linhagens celulares tumorais que foram selecionadas e apresentam reatividade cruzada a uma ampla faixa de agentes anti-tumorais. Este trabalho caracteriza uma linhagem celular com múltipla resistência a fármacos, selecionada originalmente pela resistência ao alcalóide de Vinca vincristina e derivado

  1. Regulation of Multidrug Resistance Proteins by Genistein in a Hepatocarcinoma Cell Line: Impact on Sorafenib Cytotoxicity

    OpenAIRE

    2015-01-01

    Hepatocellular carcinoma (HCC) is the fifth most frequent cancer worldwide. Sorafenib is the only drug available that improves the overall survival of HCC patients. P-glycoprotein (P-gp), Multidrug resistance-associated proteins 2 and 3 (MRP2 and 3) and Breast cancer resistance protein (BCRP) are efflux pumps that play a key role in cancer chemoresistance. Their modulation by dietary compounds may affect the intracellular accumulation and therapeutic efficacy of drugs that are substrates of t...

  2. In vivo evaluation of P-glycoprotein and breast cancer resistance protein modulation in the brain using [{sup 11}C]gefitinib

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, Kazunori [Department of Molecular Probes, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555 (Japan)], E-mail: kawamur@nirs.go.jp; Yamasaki, Tomoteru; Yui, Joji; Hatori, Akiko; Konno, Fujiko; Kumata, Katsushi; Irie, Toshiaki; Fukumura, Toshimitsu; Suzuki, Kazutoshi; Kanno, Iwao; Zhang Mingrong [Department of Molecular Probes, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555 (Japan)

    2009-04-15

    Gefitinib (Iressa) is a selective inhibitor of epidermal growth factor receptor (EGFR) tyrosine kinase. Recent studies confirmed that gefitinib interacted with the breast cancer resistance protein (BCRP) at submicromolar concentrations, whereas other multidrug transporters, including P-glycoprotein (P-gp), showed much lower reactivity toward gefitinib. Recently, many tracers for positron emission tomography (PET) have been prepared to study P-gp function in vivo; however, PET tracers had not been evaluated for both P-gp and BCRP modulation in the brain. Therefore, we evaluated in vivo brain penetration-mediated P-gp and BCRP in mice using [{sup 11}C]gefitinib. Co-injection with gefitinib (over 50 mg/kg), a nonspecific P-gp modulator cyclosporin A (50 mg/kg), and the dual P-gp and BCRP modulator GF120918 (over 5 mg/kg) induced an increase in the brain uptake of [{sup 11}C]gefitinib in mice 30 min after injection. In the PET study of mice, the radioactivity level in the brain with co-injection of GF120918 (5 mg/kg) was three- to fourfold higher than that in control after initial uptake. The radioactivity level in the brain in P-gp and Bcrp knockout mice was approximately eightfold higher than that in wild-type mice 60 min after injection. In conclusion, [{sup 11}C]gefitinib is a promising PET tracer to evaluate the penetration of gefitinib into the brain by combined therapy with P-gp or BCRP modulators, and into brain tumors. Furthermore, PET study with GF120918 is a promising approach for evaluating brain penetration-mediated P-gp and BCRP.

  3. Pregnane X receptors regulate CYP2C8 and P-glycoprotein to impact on the resistance of NSCLC cells to Taxol.

    Science.gov (United States)

    Chen, Yan; Huang, Wandan; Chen, Feiyu; Hu, Guoping; Li, Fenglei; Li, Jianhua; Xuan, Aiguo

    2016-12-01

    Cytochrome P450 2C8 (CYP2C8) is one of the enzymes that primarily participate in producing metabolisms of medications and P-glycoprotein (P-gp) has been regarded as one of the important molecules in chemotherapeutically induced multidrug resistance (MDR). In addition, the pregnane X receptor (PXR) is involved in regulating both CYP2C8 and P-gp. We aim to research the effect of PXR on Taxol-resistant non-small-cell lung cancer (NSCLC cells) via regulating CYP2C8 and P-gp. NSCLC cells were treated with SR12813, LY335979, or PXR siRNA. Cell counting kit (CCK-8) assay was used to detect cell vitality. Colony formation assay was used to observe cell proliferation. Western blotting, real-time polymerase chain reaction (RT-PCR), and immunofluorescence staining were conducted to analyze the expressions of PXR, CYP2C8, and P-gp. Taxol and its metabolic products were detected by high-performance liquid chromatography (HPLC). The expression of PXR in A549 cell line was higher than that in other cell lines. The accumulation of PXR was observed in the nucleus after cells were treated with SR12813. Besides, SR12813 induced higher expressions of CYP2C8 and P-gp proteins. We also discovered that pretreatment with SR12813 reversed the inhibition of cell viability and proliferation after the Taxol treatment in comparison to the SR12813 untreated group. Furthermore, the hydroxylation products of Taxol analyzed by HPLC were increased in comparison to the SR12813 untreated group, indicating that high expressions of CYP2C8 and P-gp enhanced the resistance of A549 cells to Taxol. For cells treated with PXR siRNA, cell viability, cell proliferation, and Taxol metabolites were significantly reduced after the Taxol treatment in comparison to the siRNA-negative group. The cell viability, cell proliferation, and Taxol metabolites were regulated by the expressions of PXR, P-gp, and CYP2C8. That is, PXR expression has an important effect on the resistance of NSCLC cells to Taxol via

  4. Postprandial chylomicron formation and fat absorption in multidrug resistance gene 2 P-glycoprotein-deficient mice

    NARCIS (Netherlands)

    Voshol, PJ; Minich, DM; Havinga, R; Elferink, RPJO; Verkade, HJJ; Groen, AK; Kuipers, F

    2000-01-01

    Background & Aims: It has been proposed that biliary phospholipids fulfill specific functions in the absorption of dietary fat from the intestine, but the physiological significance has not been established. The aim of this study was to evaluate the role of biliary phospholipids in dietary fat absor

  5. ATP-binding cassette transporters are enriched in non-caveolar detergent-insoluble glycosphingolipid-enriched membrane domains (DIGs) in human multidrug-resistant cancer cells

    NARCIS (Netherlands)

    Hinrichs, JWJ; Klappe, K; Hummel, [No Value; Kok, JW

    2004-01-01

    In this study we show that P-glycoprotein in multi-drug-resistant 2780AD human ovarian carcinoma cells and multidrug resistance-associated protein 1 in multi-drug-resistant HT29(col) human colon carcinoma cells are predominantly located in Lubrol-based detergent-insoluble glycosphingolipid-enriched

  6. Drug accumulation in the presence of the multidrug resistance pump

    DEFF Research Database (Denmark)

    Ayesh, S; Litman, Thomas; Stein, W D

    1997-01-01

    We studied the interaction between the multidrug transporter, P-glycoprotein, and two compounds that interact with it: vinblastine, a classical substrate of the pump, and verapamil, a classical reverser. Steady-state levels of accumulation of these two drugs were determined in a multidrug resista...

  7. Activity of the dietary flavonoid, apigenin, against multidrug-resistant tumor cells as determined by pharmacogenomics and molecular docking.

    Science.gov (United States)

    Saeed, Mohamed; Kadioglu, Onat; Khalid, Hassan; Sugimoto, Yoshikazu; Efferth, Thomas

    2015-01-01

    Apigenin is a common dietary flavonoid with considerable cytotoxic activity in vitro and in vivo. Despite many mechanistic studies, less is known about resistance factors hampering apigenin's activity. We investigated the ATP-binding cassette (ABC) transporters BCRP/ABCG2, P-glycoprotein/ABCB1 and its close relative ABCB5. Multidrug-resistant cells overexpressing these ABC transporters were not cross-resistant toward apigenin. Moreover, apigenin inhibited not only P-glycoprotein but also BCRP by increasing cellular uptake of doxorubicin and synergistic inhibition of cell viability in combination with doxorubicin or docetaxel in multidrug-resistant cells. To perform in silico molecular docking studies, we first generated homology models for human P-glycoprotein and ABCB5 based on the crystal structure of murine P-glycoprotein. Their nucleotide binding domains (NDBs) revealed the highest degrees of sequence homologies (89%-100%), indicating that ATP binding and cleavage is of crucial importance for ABC transporters. Molecular docking of apigenin bound to the NDBs of P-glycoprotein and ABCB5 in molecular docking studies. Hence, apigenin may compete with ATP for NDB-binding leading to energy depletion to fuel the transport of ABC transporter substrates. Furthermore, we performed COMPARE and hierarchical cluster analyses of transcriptome-wide mRNA expression profiles of the National Cancer Institute tumor cell line panel. Microarray-based mRNA expressions of genes of diverse biological functions (signal transduction, transcriptional regulation, ubiquitination, autophagy, metabolic activity, xenobiotic detoxification and microtubule formation) significantly predicted responsiveness of tumor cells to apigenin. In conclusion, apigenin's activity is not hampered by classical mechanisms of multidrug resistance and the inhibition of ABC transporters by apigenin indicates that apigenin may overcome multidrug resistance in otherwise refractory tumors.

  8. The ABC family of multidrug transporters in microorganisms

    NARCIS (Netherlands)

    van Veen, H.W; Konings, W.N

    1998-01-01

    Multidrug transporters are membrane proteins that are able to expel a broad range of toxic molecules from the cell. In humans, the overexpression of the multidrug resistance P-glycoprotein (Pgp) and the multidrug resistance-associated protein MRP1 (MRP) is a principal cause of resistance of cancers

  9. Bypassing P-Glycoprotein Drug Efflux Mechanisms: Possible Applications in Pharmacoresistant Schizophrenia Therapy

    Directory of Open Access Journals (Sweden)

    Famida G. Hoosain

    2015-01-01

    Full Text Available The efficient noninvasive treatment of neurodegenerative disorders is often constrained by reduced permeation of therapeutic agents into the central nervous system (CNS. A vast majority of bioactive agents do not readily permeate into the brain tissue due to the existence of the blood-brain barrier (BBB and the associated P-glycoprotein efflux transporter. The overexpression of the MDR1 P-glycoprotein has been related to the occurrence of multidrug resistance in CNS diseases. Various research outputs have focused on overcoming the P-glycoprotein drug efflux transporter, which mainly involve its inhibition or bypassing mechanisms. Studies into neurodegenerative disorders have shown that the P-glycoprotein efflux transporter plays a vital role in the progression of schizophrenia, with a noted increase in P-glycoprotein function among schizophrenic patients, thereby reducing therapeutic outcomes. In this review, we address the hypothesis that methods employed in overcoming P-glycoprotein in cancer and other disease states at the level of the BBB and intestine may be applied to schizophrenia drug delivery system design to improve clinical efficiency of drug therapies. In addition, the current review explores polymers and drug delivery systems capable of P-gp inhibition and modulation.

  10. The importance of drug-transporting P-glycoproteins in toxicology.

    Science.gov (United States)

    van Tellingen, O

    2001-03-31

    The importance of specific transport in toxicology is becoming increasingly clear and the work on P-glycoprotein has certainly been a major contribution to these growing insights. P-Glycoproteins were discovered by their ability to confer multidrug resistance in mammalian tumour cells. They are localised in the cell membrane where they actively extrude a wide range of compounds including many anti-cancer drugs from the cell. Besides in tumour cells, drug-transporting P-glycoproteins are also expressed in a polarised fashion in normal tissues that perform an excretory or barrier function, such as the liver, kidneys, intestines, brain endothelial cells. Based on this expression profile, it has been proposed that P-glycoproteins are important in protecting the host by reducing exposure to xenobiotics. Further studies with P-glycoprotein knockout mice have clearly established this protective function. In general, the clearance of substrate drugs is lower in knockout mice due to a diminished hepatobiliary excretion, direct intestinal excretion and/or increased enterohepatic cycling. Moreover, their uptake in sanctuary sites, such as the brain or the foetus, was profoundly higher in P-glycoprotein knockout mice, as was the uptake of drugs from the gastro-intestinal tract into the systemic circulation following oral ingestion. These results clearly highlight the impact that transport proteins can play in toxicology.

  11. Selection of resistant acute myeloid leukemia SKM-1 and MOLM-13 cells by vincristine-, mitoxantrone- and lenalidomide-induced upregulation of P-glycoprotein activity and downregulation of CD33 cell surface exposure.

    Science.gov (United States)

    Imrichova, D; Messingerova, L; Seres, M; Kavcova, H; Pavlikova, L; Coculova, M; Breier, A; Sulova, Z

    2015-09-18

    Bone marrow cells and peripheral blood mononuclear cells obtained from both acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) patients contain upregulated levels of cell surface antigen CD33 compared with healthy controls. This difference enables the use of humanized anti-CD33 antibody conjugated to cytotoxic agents for CD33 targeted immunotherapy. However, the expression of the membrane-bound drug transporter P-glycoprotein (P-gp) has been shown to be critical for resistance against the cytotoxicity of a humanized anti-CD33 antibody conjugated to maytansine-derivative DM4. The aim of the present study was to examine whether the expression of P-gp in AML cell lines is associated with changes in CD33 expression. For this purpose, we established drug resistant variants of SKM-1 and MOLM-13 AML cell lines via the selection of parental cells for resistance to vincristine, mitoxantrone and lenalidomide. All three substances induced a multidrug resistance (MDR) phenotype in SKM-1 cells associated with strong upregulation of P-gp and downregulation of CD33. However, in MOLM-13 cells, the upregulation of P-gp and downregulation of CD33 were present only in cells selected for resistance to vincristine and mitoxantrone but not lenalidomide. Inverse expression of P-gp and CD33 were observed in all resistant variants of SKM-1 and MOLM-13 cells. The MDR phenotype of resistant variants of SKM-1 and MOLM-13 cells was associated with alterations in apoptotic regulatory proteins and downregulation of the multidrug resistance associated protein 1 and breast cancer resistance protein.

  12. Enhancement of cellular uptake and cytotoxicity of curcumin-loaded PLGA nanoparticles by conjugation with anti-P-glycoprotein in drug resistance cancer cells

    Institute of Scientific and Technical Information of China (English)

    Wanisa PUNFA; Supachai YODKEEREE; Pornsiri PITCHAKARN; Chadarat AMPASAVATE; Pornngarm LIMTRAKUL

    2012-01-01

    Aim:To compare the anti-cancer activity and cellular uptake of curcumin (Cur) delivered by targeted and non-targeted drug delivery systems in multidrug-resistant cervical cancer cells.Methods:Cur was entrapped into poly (DL-lactide-co-glycolide) (PLGA) nanoparticles (Cur-NPs) in the presence of modified-pluronic F127 stabilizer using nano-precipitation technique.On the surface of Cur-NPs,the carboxy-terminal of modified pluronic F127 was conjugated to the amino-terminal of anti-P-glycoprotein (P-gp) (Cur-NPs-APgp).The physical properties of the Cur-NPs,including particle size,zeta potential,particle morphology and Cur release kinetics,were investigated.Cellular uptake and specificity of the Cur-NPs and Cur-NPs-APgp were detected in cervical cancer cell lines KB-V1 (higher expression of P-gp) and KB-3-1 (lower expression of P-gp) using fluorescence microscope and flow cytometry,respectively.Cytotoxicity of the Cur-NPs and Cur-NPs-APgp was determined using MTT assay.Results:The particle size of Cur-NPs and Cur-NPs-APgp was 127 and 132 nm,respectively.The entrapment efficiency and actual loading of Cur-NPs-APgp (60% and 5μg Cur/mg NP) were lower than those of Cur-NPs (99% and 7 μg Cur/mg NP).The specific binding of Cur-NPs-APgp to KB-V1 cells was significantly higher than that to KB-3-1 cells.Cellular uptake of Cur-NPs-APgp into KB-V1 cells was higher,as compared to KB-3-1 cells.However,the cellular uptake of Cur-NPs and Cur-NPs-lgG did not differ between the two types of cells.Besides,the cytotoxicity of Cur-NPs-APgp in KB-V1 cells was higher than those of Cur and Cur-NPs.Conclusion:The results demonstrate that Cur-NPs-APgp targeted to P-gp on the cell surface membrane of KB-V1 cells,thus enhancing the cellular uptake and cytotoxicity of Cur.

  13. The T687G SNP in a P-glycoprotein gene of Fasciola hepatica is not associated with resistance to triclabendazole in two resistant Australian populations.

    Science.gov (United States)

    Elliott, Timothy P; Spithill, Terry W

    2014-11-01

    Triclabendazole (TCBZ) is widely used for control of Fasciola hepatica (liver fluke) in animals and humans and resistance to this drug is now widespread. However, the mechanism of resistance to TCBZ is not known. A T687G single nucleotide polymorphism (SNP) in a P-glycoprotein gene was proposed as a molecular marker for TCBZ resistance in F. hepatica (Wilkinson et al., 2012). We analyzed this Pgp gene from TCBZ-susceptible and TCBZ-resistant populations from Australia to determine if the SNP was a marker for TCBZ resistance. From the 21 parasites studied we observed 27 individual haplotypes in the Pgp sequences which comprised seven haplotypic groups (A-G), with haplotypes A and B representing 81% of the total observed. The T687G SNP was not observed in either of the resistant or susceptible populations. We conclude that the T687G SNP in this Pgp gene is not associated with TCBZ resistance in these Australian F. hepatica populations and therefore unlikely to be a universal molecular marker for TCBZ resistance.

  14. CD44-engineered mesoporous silica nanoparticles for overcoming multidrug resistance in breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xin; Liu, Ying; Wang, Shouju; Shi, Donghong [Department of Radiology, Jinling Hospital, Clinical School of Medical College, Nanjing University, Nanjing 210002 (China); Zhou, Xianguang [National Clinical Research Center of Kidney Diseases, Jinling Hospital, Nanjing 210016 (China); Wang, Chunyan; Wu, Jiang; Zeng, Zhiyong; Li, Yanjun; Sun, Jing [Department of Radiology, Jinling Hospital, Clinical School of Medical College, Nanjing University, Nanjing 210002 (China); Wang, Jiandong [Department of Pathology, Jinling Hospital, Clinical School of Medical College, Nanjing University, Nanjing 210002 (China); Zhang, Longjiang [Department of Radiology, Jinling Hospital, Clinical School of Medical College, Nanjing University, Nanjing 210002 (China); Teng, Zhaogang, E-mail: tzg@fudan.edu.cn [Department of Radiology, Jinling Hospital, Clinical School of Medical College, Nanjing University, Nanjing 210002 (China); State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Lu, Guangming, E-mail: cjr.luguangming@vip.163.com [Department of Radiology, Jinling Hospital, Clinical School of Medical College, Nanjing University, Nanjing 210002 (China); State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China)

    2015-03-30

    Graphical abstract: - Highlights: • CD44-engineered mesoporous silica nanoparticles are synthesized. • The mechanism of CD44-engineered mesoporous silica nanoparticles is revealed. • This new delivery system increased the drug accumulation in vitro and in vivo. • This new delivery system offers an effective approach to treat multidrug resistance. - Abstract: Multidrug resistance is a major impediment for the successful chemotherapy in breast cancer. CD44 is over-expressed in multidrug resistant human breast cancer cells. CD44 monoclonal antibody exhibits anticancer potential by inhibiting proliferation and regulating P-glycoprotein-mediated drug efflux activity in multidrug resistant cells. Thereby, CD44 monoclonal antibody in combination with chemotherapeutic drug might be result in enhancing chemosensitivity and overcoming multidrug resistance. The purpose of this study is to investigate the effects of the CD44 monoclonal antibody functionalized mesoporous silica nanoparticles containing doxorubicin on human breast resistant cancer MCF-7 cells. The data showed that CD44-modified mesoporous silica nanoparticles increased cytotoxicity and enhanced the downregulation of P-glycoprotein in comparison to CD44 antibody. Moreover, CD44-engineered mesoporous silica nanoparticles provided active target, which promoted more cellular uptake of DOX in the resistant cells and more retention of DOX in tumor tissues than unengineered counterpart. Animal studies of the resistant breast cancer xenografts demonstrated that CD44-engineered drug delivery system remarkably induced apoptosis and inhibited the tumor growth. Our results indicated that the CD44-engineered mesoporous silica nanoparticle-based drug delivery system offers an effective approach to overcome multidrug resistance in human breast cancer.

  15. Tumor endothelial expression of P-glycoprotein upon microvesicular transfer of TrpC5 derived from adriamycin-resistant breast cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Dong, YePing; Pan, QiongXi; Jiang, Li; Chen, Zhen; Zhang, FangFang; Liu, YanJun; Xing, Hui; Shi, Mei; Li, Jiao; Li, XiYuan; Zhu, YaoDan; Chen, Yun; Bruce, Iain C.; Jin, Jian, E-mail: jinjian31@126.com; Ma, Xin, E-mail: maxin@jiangnan.edu.cn

    2014-03-28

    Highlights: • TrpC5 was mainly accumulated in microvesicles of drug-resistant MCF-7/ADM cells. • Microvesicles from MCF-7/ADM transferred TrpC5 to endothelial cells. • TrpC5 inhibition reduced P-glycoprotein accumulation on tumor blood vessels in vivo. - Abstract: Treatment of carcinoma commonly fails due to chemoresistance. Studies have shown that endothelial cells acquire resistance via the tumor microenvironment. Microvesicle (MV) shedding from the cell membrane to the microenvironment plays an important role in communication between cells. The aim of the present study was to determine whether MCF-7 adriamycin-resistant cells (MCF-7/ADM) shed MVs that alter the characteristics of human microvessel endothelial cells (HMECs). MVs from tumor cells transferred a Ca{sup 2+}-permeable channel TrpC5 to HMECs, inducing the expression of P-glycoprotein (P-gp) by activation of the transcription factor NFATc3 (nuclear factor of activated T cells isoform c3). Expression of the mdr1 gene was blocked by the TrpC5-blocking antibody T5E3, and the production of P-gp in HMECs was reduced by blockade of TrpC5. Thus, we postulate that endothelial cells acquire the resistant protein upon exposure to TrpC5-containg MVs in the microenvironment, and express P-gp in the TrpC5–NFATc3 signal pathway.

  16. P-glycoprotein targeted nanoscale drug carriers

    KAUST Repository

    Li, Wengang

    2013-02-01

    Multi-drug resistance (MDR) is a trend whereby tumor cells exposed to one cytotoxic agent develop cross-resistance to a range of structurally and functionally unrelated compounds. P -glycoprotein (P -gp) efflux pump is one of the mostly studied drug carrying processes that shuttle the drugs out of tumor cells. Thus, P -gp inhibitors have attracted a lot of attention as they can stop cancer drugs from being pumped out of target cells with the consumption of ATP. Using quantitive structure activity relationship (QSAR), we have successfully synthesized a series of novel P -gp inhibitors. The obtained dihydropyrroloquinoxalines series were fully characterized and then tested against bacterial and tumor assays with over-expressed P -gps. All compounds were bioactive especially compound 1c that had enhanced antibacterial activity. Furthermore, these compounds were utilized as targeting vectors to direct drug delivery vehicles such as silica nanoparticles (SNPs) to cancerous Hela cells with over expressed P -gps. Cell uptake studies showed a successful accumulation of these decorated SNPs in tumor cells compared to undecorated SNPs. The results obtained show that dihydropyrroloquinoxalines constitute a promising drug candidate for targeting cancers with MDR. Copyright © 2013 American Scientific Publishers All rights reserved.

  17. Resistance to the macrocyclic lactone moxidectin is mediated in part by membrane transporter P-glycoproteins: Implications for control of drug resistant parasitic nematodes.

    Science.gov (United States)

    Bygarski, Elizabeth E; Prichard, Roger K; Ardelli, Bernadette F

    2014-12-01

    Our objective was to determine if the resistance mechanism to moxidectin (MOX) is similar of that to ivermectin (IVM) and involves P-glycoproteins (PGPs). Several Caenorhabditis elegans strains were used: an IVM and MOX sensitive strain, 13 PGP deletion strains and the IVM-R strain which shows synthetic resistance to IVM (by creation of three point mutations in genes coding for α-subunits of glutamate gated chloride channels [GluCls]) and cross-resistance to MOX. These strains were used to compare expression of PGP genes, measure motility and pharyngeal pumping phenotypes and evaluate the ability of compounds that inhibit PGP function to potentiate sensitivity or reverse resistance to MOX. The results suggest that C. elegans may use regulation of PGPs as a response mechanism to MOX. This was indicated by the over-expression of several PGPs in both drug sensitive and IVM-R strains and the significant changes in phenotype in the IVM-R strain in the presence of PGP inhibitors. However, as the inhibitors did not completely disrupt expression of the phenotypic traits in the IVM-R strain, this suggests that there likely are multiple avenues for MOX action that may include receptors other than GluCls. If MOX resistance was mediated solely by GluCls then exposure of the IVM-R strain to PGP inhibitors should not have affected sensitivity to MOX. Targeted gene deletions showed that protection of C. elegans against MOX involves complex mechanisms and depends on the PGP gene family, particularly PGP-6. While the results presented are similar to others using IVM, there were some important differences observed with respect to PGPs which may play a role in the disparities seen in the characteristics of resistance to IVM and MOX. The similarities are of concern as parasites resistant to IVM show some degree but not complete cross-resistance to MOX; this could impact nematodes that are resistant to IVM.

  18. Resistance to the macrocyclic lactone moxidectin is mediated in part by membrane transporter P-glycoproteins: Implications for control of drug resistant parasitic nematodes

    Directory of Open Access Journals (Sweden)

    Elizabeth E. Bygarski

    2014-12-01

    Full Text Available Our objective was to determine if the resistance mechanism to moxidectin (MOX is similar of that to ivermectin (IVM and involves P-glycoproteins (PGPs. Several Caenorhabditis elegans strains were used: an IVM and MOX sensitive strain, 13 PGP deletion strains and the IVM-R strain which shows synthetic resistance to IVM (by creation of three point mutations in genes coding for α-subunits of glutamate gated chloride channels [GluCls] and cross-resistance to MOX. These strains were used to compare expression of PGP genes, measure motility and pharyngeal pumping phenotypes and evaluate the ability of compounds that inhibit PGP function to potentiate sensitivity or reverse resistance to MOX. The results suggest that C. elegans may use regulation of PGPs as a response mechanism to MOX. This was indicated by the over-expression of several PGPs in both drug sensitive and IVM-R strains and the significant changes in phenotype in the IVM-R strain in the presence of PGP inhibitors. However, as the inhibitors did not completely disrupt expression of the phenotypic traits in the IVM-R strain, this suggests that there likely are multiple avenues for MOX action that may include receptors other than GluCls. If MOX resistance was mediated solely by GluCls then exposure of the IVM-R strain to PGP inhibitors should not have affected sensitivity to MOX. Targeted gene deletions showed that protection of C. elegans against MOX involves complex mechanisms and depends on the PGP gene family, particularly PGP-6. While the results presented are similar to others using IVM, there were some important differences observed with respect to PGPs which may play a role in the disparities seen in the characteristics of resistance to IVM and MOX. The similarities are of concern as parasites resistant to IVM show some degree but not complete cross-resistance to MOX; this could impact nematodes that are resistant to IVM.

  19. The inhibitory and combinative mechanism of HZ08 with P-glycoprotein expressed on the membrane of Caco-2 cell line

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yanyan; Hu, Yahui; Feng, Yidong; Kodithuwakku, Nandani Darshika; Fang, Weirong [State Key Laboratory of Natural Medicines, Department of Physiology, China Pharmaceutical University, Nanjing 210009 (China); Li, Yunman, E-mail: yunmanlicpu@hotmail.com [State Key Laboratory of Natural Medicines, Department of Physiology, China Pharmaceutical University, Nanjing 210009 (China); Huang, Wenlong [Center of Drug Discovery, China Pharmaceutical University, Nanjing 210009 (China)

    2014-01-15

    Recently, the research and development of agents to reverse the phenomenon of multidrug resistance has been an attractive goal as well as a key approach to elevating the clinical survival of cancer patients. Although three generations of P-glycoprotein modulators have been identified, poor clearance and metabolism render these agents too toxic to be used in clinical application. HZ08, which has been under investigation for several years, shows a dramatic reversal effect with low cytotoxicity. For the first time, we aimed to describe the interaction between HZ08 and P-glycoprotein in Caco-2 cell line in which P-glycoprotein is overexpressed naturally. Cytotoxicity and multidrug resistance reversal assays, together with flow cytometry, fluorescence microscopy and siRNA interference as well as Caco-2 monolayer transport model were employed in this study to evaluate the interaction between HZ08 and P-glycoprotein. This study revealed that HZ08 was capable of reversing adriamycin resistance mediated by P-glycoprotein as a result of intracellular enhancement of adriamycin accumulation, which was found to be superior to verapamil. In addition, we confirmed that HZ08 suppressed the transport of Rhodamine123 in the Caco-2 monolayer model but had little effect on P-glycoprotein expression. The transport of HZ08 was diminished by P-glycoprotein inhibitors (verapamil and LY335979) and its accumulation was increased via siRNA targeting MDR1 in Caco-2 cells. Furthermore, considering the binding site of P-glycoprotein, verapamil performed as a competitive inhibitor with HZ08. In conclusion, as a P-glycoprotein substrate, HZ08 inhibited P-glycoprotein activity and may share the same binding site of verapamil to P-glycoprotein. - Highlights: • The cytotoxicity and reversing effect of HZ08 was measured in Caco-2 cell line. • HZ08 inhibited the transport of Rhodamine123 across Caco-2 cell monolayer. • The efflux ratio of HZ08 was dropped when combined with P-glycoprotein

  20. Ceramide 1-Phosphate Increases P-Glycoprotein Transport Activity at the Blood-Brain Barrier via Prostaglandin E2 Signaling.

    Science.gov (United States)

    Mesev, Emily V; Miller, David S; Cannon, Ronald E

    2017-04-01

    P-glycoprotein, an ATP-driven efflux pump, regulates permeability of the blood-brain barrier (BBB). Sphingolipids, endogenous to brain tissue, influence inflammatory responses and cell survival in vitro. Our laboratory has previously shown that sphingolipid signaling by sphingosine 1-phosphate decreases basal P-glycoprotein transport activity. Here, we investigated the potential for another sphingolipid, ceramide 1-phosphate (C1P), to modulate efflux pumps at the BBB. Using confocal microscopy and measuring luminal accumulation of fluorescent substrates, we assessed the transport activity of several efflux pumps in isolated rat brain capillaries. C1P treatment induced P-glycoprotein transport activity in brain capillaries rapidly and reversibly. In contrast, C1P did not affect transport activity of two other major efflux transporters, multidrug resistance protein 2 and breast cancer resistance protein. C1P induced P-glycoprotein transport activity without changing transporter protein expression. Inhibition of the key signaling components in the cyclooxygenase-2 (COX-2)/prostaglandin E2 signaling cascade (phospholipase A2, COX-2, multidrug resistance protein 4, and G-protein-coupled prostaglandin E2 receptors 1 and 2), abolished P-glycoprotein induction by C1P. We show that COX-2 and prostaglandin E2 are required for C1P-mediated increases in P-glycoprotein activity independent of transporter protein expression. This work describes how C1P activates a signaling cascade to dynamically regulate P-glycoprotein transport at the BBB and offers potential clinical targets to modulate neuroprotection and drug delivery to the CNS.

  1. BME, a novel compound of anthraquinone, down regulated P-glycoprotein expression in doxorubicin-resistant human myelogenous leukemia (K562/DOX) cells via generation of reactive oxygen species.

    Science.gov (United States)

    Wang, Jianhong; Liu, Lu; Cen, Juan; Ji, Biansheng

    2015-09-01

    P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) in tumor cells is still a main obstacle for the chemotherapeutic treatment of cancers. Thus, development of effective MDR reversing agents is an important approach in the clinic. The present study revealed that BME, a novel compound of anthraquinone, elevated intracellular accumulation of the P-gp substrates and reduced concentration resulting in 50% inhibition of cell growth (IC50) values for doxorubicin (DOX) in doxorubicin-resistant human myelogenous leukemia (K562/DOX) cells. Further more, BME was also reported to down regulated P-gp expression accompanying with generation of nontoxic low level of intracellular reactive oxygen species (iROS) and activation of extracellular signal-regulated kinase (ERK)1/2 as well as c-JUN N-terminal kinase (JNK). However, treatment with N-acetyl-cysteine (NAC), U0216 and SP600125 almost abolished actions of the BME mentioned above. These results indicated that the effect of the BME on the P-gp may be involved in generation of nontoxic low level of iROS and activation of ERK1/2 or JNK, which suggested valuable clues to screen and develop P-gp reversing agents.

  2. Molecular Pathways: Regulation and Therapeutic Implications of Multidrug Resistance

    Science.gov (United States)

    Chen, Kevin G.; Sikic, Branimir I.

    2012-01-01

    Multidrug transporters constitute major mechanisms of multidrug resistance (MDR) in human cancers. The ABCB1 (MDR1) gene encodes a well-characterized transmembrane transporter, termed P-glycoprotein (P-gp), which is expressed in many normal human tissues and cancers. P-gp plays a major role in the distribution and excretion of drugs, and is involved in intrinsic and acquired drug resistance of cancers. The regulation of ABCB1 expression is complex, and has not been well studied in a clinical setting. In this review, we elucidate molecular signaling and epigenetic interactions that govern ABCB1 expression and the development of MDR in cancer. We focus on acquired expression of ABCB1 that is associated with genomic instability of cancer cells, including mutational events that alter chromatin structures, gene rearrangements, and mutations in tumor suppressor proteins (e.g., mutant p53) that guard the integrity of genome. In addition, epigenetic modifications of the ABCB1 proximal and far upstream promoters by either demethylation of DNA or acetylation of histone H3 play a pivotal role in inducing ABCB1 expression. We describe a molecular network that coordinates genetic and epigenetic events leading to the activation of ABCB1. These mechanistic insignts provide additional translational targets and potential strategies to deal with clinical MDR. PMID:22344233

  3. Iodination increases the activity of verapamil derivatives in reversing PGP multidrug resistance.

    Science.gov (United States)

    Barattin, Regis; Gerby, Bastien; Bourges, Kevin; Hardy, Gaëlle; Olivares, Jose; Boutonnat, Jean; Arnoult, Christophe; D'Hardemare, Amaury D U Moulinet; Ronot, Xavier

    2010-07-01

    Iodinated derivatives of verapamil were synthesized and tested as P-glycoprotein (Pgp)-mediated multidrug resistance (MDR) reversal agents. The ability of these compounds to revert MDR was evaluated on daunorubicin-resistant K562 cells, by measuring the intracellular accumulation of rhodamine 123, a fluorescent probe of Pgp transport activity. One of the investigated compounds (16c) was found to be a more potent MDR reversal agent than verapamil and cyclosporin A, used as reference molecules. Further in vitro studies showed that compound 16c restored daunorubicin activity and, when used alone, did not induce cell death, cell cycle perturbation and modification of calcium channel activity in comparison with verapamil.

  4. IPEC-J2 MDR1, a Novel High-Resistance Cell Line with Functional Expression of Human P-glycoprotein (ABCB1) for Drug Screening Studies

    DEFF Research Database (Denmark)

    Saaby, Lasse; Helms, Hans Christian Cederberg; Brodin, Birger

    2016-01-01

    The P-glycoprotein (P-gp) efflux pump has been shown to affect drug distribution and absorption in various organs and to cause drug resistance in cancer therapy. The aim of this work was to develop a cell line to serve as a screening system for potential substrates of P-gp. This requires a cell...... line with high paracellular tightness, low expression of nonhuman ABC transporters, and high expression of functional human P-gp (ABCB1). The porcine intestinal epithelial cell line, IPEC-J2, was selected as a transfection host, due to its ability to form extremely high-resistance monolayers (>10,000 Ω...... for the efflux transport by substrate profiling, combined with application of P-gp and BCRP inhibitors. Furthermore, the compounds atenolol, citalopram, and mitoxantrone were identified as P-gp substrates. Functional P-gp expression was shown to be stable through at least 10 cell passages. In conclusion...

  5. Acute myeloid leukemia cells MOLM-13 and SKM-1 established for resistance by azacytidine are crossresistant to P-glycoprotein substrates.

    Science.gov (United States)

    Messingerova, Lucia; Imrichova, Denisa; Kavcova, Helena; Turakova, Katarina; Breier, Albert; Sulova, Zdena

    2015-10-01

    Establishment of the acute myeloid leukemia cells SKM-1 and MOLM-13 for resistance by azacytidine (AzaC) resulted in SKM-1/AzaC and MOLM-13/AzaC cell variants with reduced sensitivity to AzaC. Despite the fact that AzaC is not substrate of P-glycoprotein (P-gp), the adaptation procedure resulted in an induction in P-gp expression/efflux activity that confers crossresistance to P-gp substrates in both resistant cell variants. While the resistance to P-gp substrates in SKM-1/AzaC and MOLM-13/AzaC cells could be reversed by the P-gp inhibitors, resistance to AzaC was insensitive to these inhibitors in both resistant cell variants. In addition, NF-κB and the antiapoptotic protein Bcl-2 were downregulated and the proapoptotic proteins Bax and p53 were upregulated in both resistant cell variants when compared with their sensitive counterparts. Moreover, at least five times the elevation in overall glutathione S-transferase activity was measured with 1-chloro-2, 5-dinitrobenzene as a substrate in the resistant variant of both cell lines. Taken together, the findings of the present study indicate that the treatment of AML cells with AzaC might lead to a drug resistance phenotype that may be associated with cross resistance to P-gp substrates and substrates of glutathione S-transferases.

  6. P-glycoprotein is expressed and causes resistance to chemotherapy in EBV-positive T-cell lymphoproliferative diseases.

    Science.gov (United States)

    Yoshimori, Mayumi; Takada, Honami; Imadome, Ken-Ichi; Kurata, Morito; Yamamoto, Kouhei; Koyama, Takatoshi; Shimizu, Norio; Fujiwara, Shigeyoshi; Miura, Osamu; Arai, Ayako

    2015-10-01

    Epstein-Barr virus-positive T-cell lymphoproliferative diseases (EBV-T-LPDs) are rare lymphomas with poor prognosis. Although chemotherapeutic strategies such as CHOP have been often selected, they have exhibited only limited efficacy. To clarify the mechanism of chemoresistance, we examined P-glycoprotein (P-gp) expression. P-gp acts as an energy-dependent efflux pump that excretes drugs from the cytoplasm, resulting in low-intracellular drug concentrations and poor sensitivity to chemotherapy. We examined P-gp expression in EBV-positive cells by immunohistochemistry staining in three patients of EBV-T-LPDs and the expression was detected in all patients. We also examined mdr1 mRNA expression by reverse-transcriptase polymerase-chain reaction (RT-PCR) in EBV-positive tumor cells from these patients and additional three patients. The expression was detected in all examined patients. In five EBV-T-LPDs patients, P-gp function was detected by Rhodamine-123 efflux assay in these cells. The efflux was inhibited by treatment with a P-gp inhibitor, cyclosporine A (CsA). We also examined and detected P-gp expression in EBV-positive T-cell lines SNT8 and SNT16 established from EBV-T-LPDs patients, by RT-PCR and western blotting. The function was also detected by Rhodamine-123 efflux in these cell lines. Inhibition and knock down of P-gp by CsA and siRNA, respectively, enhanced etoposide- and doxorubicin-induced cell death in the EBV-positive T-cell lines. Finally, we infected the T-cell line MOLT4 with EBV, and found that mdr1 mRNA expression and Rhodamine 123 efflux were upregulated after infection. These results indicated that enhanced P-gp expression contributed to the chemoresistance of EBV-T-LPDs.

  7. P-glycoprotein alters blood–brain barrier penetration of antiepileptic drugs in rats with medically intractable epilepsy

    Directory of Open Access Journals (Sweden)

    Ma A

    2013-12-01

    Full Text Available Aimei Ma,1,* Cuicui Wang,2,3,* Yinghui Chen,2,3 Weien Yuan4 1Department of Neurology, The People's Hospital of Shanxi Province, Taiyuan, 2Department of Neurology, Jinshan Hospital, Fudan University, 3Department of Neurology, Shanghai Medical College, Shanghai, 4School of Pharmacy, Shanghai JiaoTong University, Shanghai, People's Republic of China *These authors contributed equally to this work Abstract: P-glycoprotein is one of the earliest known multidrug transporters and plays an important role in resistance to chemotherapeutic drugs. In this study, we detected levels of P-glycoprotein and its mRNA expression in a rat brain model of medically intractable epilepsy established by amygdala kindling and drug selection. We investigated whether inhibition of P-glycoprotein affects the concentration of antiepileptic drugs in cortical extracellular fluid. We found that levels of P-glycoprotein and its mRNA expression were upregulated in epileptic cerebral tissue compared with cerebral tissue from normal rats. The concentrations of two antiepileptic drugs, carbamazepine and phenytoin, were very low in the cortical extracellular fluid of rats with medically intractable epilepsy, and were restored after blockade of P-glycoprotein by verapamil. These results show that increased P-glycoprotein levels alter the ability of carbamazepine and phenytoin to penetrate the blood–brain barrier and reduce the concentrations of these agents in extracellular cortical fluid. High P-glycoprotein levels may be involved in resistance to antiepileptic drugs in medically intractable epilepsy. Keywords: P-glycoprotein, medically intractable epilepsy, antiepileptic drugs, amygdala kindling, verapamil

  8. eEF-2 Phosphorylation Down-Regulates P-Glycoprotein Over-Expression in Rat Brain Microvessel Endothelial Cells.

    Directory of Open Access Journals (Sweden)

    Xing Hua Tang

    Full Text Available We investigated whether glutamate, NMDA receptors, and eukaryote elongation factor-2 kinase (eEF-2K/eEF-2 regulate P-glycoprotein expression, and the effects of the eEF-2K inhibitor NH125 on the expression of P-glycoprotein in rat brain microvessel endothelial cells (RBMECs.Cortex was obtained from newborn Wistar rat brains. After surface vessels and meninges were removed, the pellet containing microvessels was resuspended and incubated at 37°C in culture medium. Cell viability was assessed by the MTT assay. RBMECs were identified by immunohistochemistry with anti-vWF. P-glycoprotein, phospho-eEF-2, and eEF-2 expression were determined by western blot analysis. Mdr1a gene expression was analyzed by RT-PCR.Mdr1a mRNA, P-glycoprotein and phospho-eEF-2 expression increased in L-glutamate stimulated RBMECs. P-glycoprotein and phospho-eEF-2 expression were down-regulated after NH125 treatment in L-glutamate stimulated RBMECs.eEF-2K/eEF-2 should have played an important role in the regulation of P-glycoprotein expression in RBMECs. eEF-2K inhibitor NH125 could serve as an efficacious anti-multidrug resistant agent.

  9. Nanodrug Delivery in Reversing Multidrug Resistance in Cancer Cells

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    Sonali eKapse-Mistry

    2014-07-01

    Full Text Available Different mechanisms in cancer cells become resistant to one or more chemotherapeutics is known as multidrug resistance(MDR which hinders chemotherapy efficacy. Potential factors for MDR includes enhanced drug detoxification, decreased drug uptake, increased intracellular nucleophiles levels, enhanced repair of drug induced DNA damage, overexpression of drug transporter such as P-glycoprotein(P-gp, multidrug resistance-associated proteins(MRP1, MRP2 and breast cancer resistance protein(BCRP. Currently nanoassemblies such as polymeric/solid lipid/inorganic/metal nanoparticles, quantum dots, dendrimers, liposomes, micelles has emerged as an innovative, effective and promising platforms for treatment of drug resistant cancer cells. Nanocarriers have potential to improve drug therapeutic index, ability for multifunctionality, divert ABC-transporter mediated drug efflux mechanism and selective targeting to tumor cells, cancer stem cells, tumor initiating cells or cancer microenvironment. Selective nanocarrier targeting to tumor overcomes dose-limiting side effects, lack of selectivity, tissue toxicity, limited drug access to tumor tissues, high drug doses and emergence of multiple drug resistance with conventional or combination chemotherapy. Current review highlights various nanodrug delivery systems to overcome mechanism of MDR by neutralizing, evading or exploiting the drug efflux pumps and those independent of drug efflux pump mechanism by silencing Bcl-2 and HIF1 gene expressions by siRNA and miRNA, modulating ceramide levels and targeting NF-B. Theragnostics combining a cytotoxic agent, targeting moiety, chemosensitizing agent and diagnostic imaging aid are highlighted as effective and innovative systems for tumor localization and overcoming MDR. Physical approaches such as combination of drug with thermal/ultrasound/photodynamic therapies to overcome MDR are focused. The review focuses on newer drug delivery systems developed to overcome

  10. Multidrug Resistance: An Emerging Crisis

    Directory of Open Access Journals (Sweden)

    Jyoti Tanwar

    2014-01-01

    Full Text Available The resistance among various microbial species (infectious agents to different antimicrobial drugs has emerged as a cause of public health threat all over the world at a terrifying rate. Due to the pacing advent of new resistance mechanisms and decrease in efficiency of treating common infectious diseases, it results in failure of microbial response to standard treatment, leading to prolonged illness, higher expenditures for health care, and an immense risk of death. Almost all the capable infecting agents (e.g., bacteria, fungi, virus, and parasite have employed high levels of multidrug resistance (MDR with enhanced morbidity and mortality; thus, they are referred to as “super bugs.” Although the development of MDR is a natural phenomenon, the inappropriate use of antimicrobial drugs, inadequate sanitary conditions, inappropriate food-handling, and poor infection prevention and control practices contribute to emergence of and encourage the further spread of MDR. Considering the significance of MDR, this paper, emphasizes the problems associated with MDR and the need to understand its significance and mechanisms to combat microbial infections.

  11. Multidrug resistance: an emerging crisis.

    Science.gov (United States)

    Tanwar, Jyoti; Das, Shrayanee; Fatima, Zeeshan; Hameed, Saif

    2014-01-01

    The resistance among various microbial species (infectious agents) to different antimicrobial drugs has emerged as a cause of public health threat all over the world at a terrifying rate. Due to the pacing advent of new resistance mechanisms and decrease in efficiency of treating common infectious diseases, it results in failure of microbial response to standard treatment, leading to prolonged illness, higher expenditures for health care, and an immense risk of death. Almost all the capable infecting agents (e.g., bacteria, fungi, virus, and parasite) have employed high levels of multidrug resistance (MDR) with enhanced morbidity and mortality; thus, they are referred to as "super bugs." Although the development of MDR is a natural phenomenon, the inappropriate use of antimicrobial drugs, inadequate sanitary conditions, inappropriate food-handling, and poor infection prevention and control practices contribute to emergence of and encourage the further spread of MDR. Considering the significance of MDR, this paper, emphasizes the problems associated with MDR and the need to understand its significance and mechanisms to combat microbial infections.

  12. High functional P-glycoprotein activity is more often present in T-cell acute lymphoblastic leukaemic cells in adults than in children

    NARCIS (Netherlands)

    Plasschaert, SLA; Vellenga, E; De Bont, ESJM; van der Kolk, D.M.; Veerman, AJP; Sluiter, WJ; Daenen, SMG; De Vries, EGE; Kamps, WA

    2003-01-01

    There is a distinct difference in prognosis between childhood versus adult acute lymphoblastic leukaemia (ALL). To define whether multidrug resistance (MDR) genes might contribute to this distinction, the expression and functional activity of P-glycoprotein (P-gp) and MDR associated proteins (MRP) w

  13. Multi-drug resistance gene (MDR1) and opioid analgesia in horses

    OpenAIRE

    Natalini Cláudio Corrêa; Cunha Anderson Fávaro da; Linardi Renata Lehn

    2006-01-01

    Opioid absorption in the intestinal tract as well as its effects in the central nervous system is modulated by the P-glycoprotein (P-gp) encoded in the Multi-drug Resistance gene (MDR1) also named ATP-binding cassete, subfamily B, member 1 (ABCB1). This MDR1 gene acts as a selective pump. The expression of this protein in humans and rodents inhibits cellular uptake of substrate opioids. The presence of the intestinal iso-enzyme CYP3A4 associated with MDR1 gene decreases the opioid analgesic a...

  14. Expression of multidrug resistance-related markers in primary neuroblastoma

    Institute of Scientific and Technical Information of China (English)

    吕庆杰; 董芳; 张锦华; 李晓晗; 马颖; 姜卫国

    2004-01-01

    Background Multidrug resistance is associated with a poor prognosis in various human cancers. However, the clinical significance of the expression of multidrug resistance-related markers in neuroblastoma is still on debate. In this study, the effect of the expression of p-glycoprotein (P-gp), multidrug resistance-associated protein (MRP), and lung resistance protein (LRP) in neuroblastoma was evaluated. Methods The streptavidin-biotin immunoperoxidase (SP) technique was used to evaluate the expression of P-gp, MRP, and LRP in 70 cases of untreated primary neuroblastoma. Results The frequencies of the expression of P-gp, MRP, and LRP were 61.4%, 38.6%, and 24.3%, respectively. A significant positive correlation was observed between P-gp and MRP expression (P=0.001), as well as between LRP and MRP expression (P=0.01). The rates of expression of P-gp and MRP were higher in tumors from patients aged greater than one year old than in tumors from patients aged less than 1 year old at time of diagnosis (P=0.01 and 0.018, respectively). MRP expression in tumors that had metastasized was significantly more frequent than in tumors that had not metastasized (P=0.015). The expression of all tested proteins showed a significant relationship with whether or not the tumor had differentiated (P=0.006, 0.000 or 0.001, respectively). MRP expression was significantly associated with a reduction in both median survival time and 2-year cumulative survival (P=0.02). By contrast, P-gp and MRP expression did not correlate with survival. According to Cox regression analysis, only the co-expression of P-gp and MRP had significant prognostic value (relative hazard, 3.513, P=0.033). Conclusions The intrinsic, multidrug resistance of neuroblastoma involves the combined effects of P-gp, MRP, and LRP. MRP expression may be an important factor determining prognosis in neuroblastoma.

  15. Stereoselective Modulation of P-Glycoprotein by Chiral Small Molecules.

    Science.gov (United States)

    Carocci, Alessia; Catalano, Alessia; Turi, Francesco; Lovece, Angelo; Cavalluzzi, Maria M; Bruno, Claudio; Colabufo, Nicola A; Contino, Marialessandra; Perrone, Maria G; Franchini, Carlo; Lentini, Giovanni

    2016-01-01

    Inhibition of drug efflux pumps such as P-glycoprotein (P-gp) is an approach toward combating multidrug resistance, which is a significant hurdle in current cancer treatments. To address this, N-substituted aryloxymethyl pyrrolidines were designed and synthesized in their homochiral forms in order to investigate the stereochemical requirements for the binding site of P-gp. Our study provides evidence that the chiral property of molecules could be a strategy for improving the capacity for interacting with P-gp, as the most active compounds of the series stereoselectively modulated this efflux pump. The naphthalene-1-yl analogue (R)-2-[(2,3-dichlorophenoxy)methyl]-1-(naphthalen-1-ylmethyl)pyrrolidine) [(R)-7 a] emerged foremost for its potency and stereoselectivity toward P-gp, with the S enantiomer being nearly inactive. The modulation of P-gp by (R)-7 a involved consumption of ATP, thus demonstrating that the compound behaves as a P-gp substrate.

  16. 2-Pyrrolinodoxorubicin and its peptide-vectorized form bypass multidrug resistance.

    Science.gov (United States)

    Castex, Cédric; Merida, Peggy; Blanc, Emmanuelle; Clair, Philippe; Rees, Anthony R; Temsamani, Jamal

    2004-07-01

    A well-known mechanism leading to the emergence of multidrug-resistant tumor cells is the overexpression of P-glycoprotein, which is capable of lowering intracellular drug concentrations. In the present study, we tested the capability of 2-pyrrolinodoxorubicin (p-DOX), a highly potent derivative of DOX, to bypass multidrug resistance. The accumulation, intracellular distribution and cytotoxicity of p-DOX were tested in two cell lines (K562 and A2780) and their DOX-resistant counterparts (K562/ADR and A2780/ADR). Cellular accumulation and cytotoxicity were dramatically lowered for DOX in resistant cell lines, in comparison with non-resistant cells. In contrast, cellular accumulation, intracellular distribution and cytotoxicity of p-DOX were independent of the nature of the cell lines. The p-DOX showed potent dose-dependent inhibition of cell growth against resistant cells as compared with DOX. After treatment of resistant cells with verapamil, the intracellular levels of DOX were markedly increased and consequent cytotoxicity improved. In contrast, treatment of resistant cells with verapamil did not cause any further enhancement of cell uptake or an increase in the cytotoxic effect of the derivative p-DOX, indicating that the compound bypasses the P-glycoprotein. Finally, we show that vectorization of p-DOX by a peptide vector (SynB3) which has been shown to enhance the brain uptake of DOX and to decrease its heart accumulation does not affect this property. These results indicate that p-DOX and its vectorized form are potent and effective in overcoming multidrug resistance.

  17. The reversal effects of 3-bromopyruvate on multidrug resistance in vitro and in vivo derived from human breast MCF-7/ADR cells.

    Directory of Open Access Journals (Sweden)

    Long Wu

    Full Text Available P-glycoprotein mediated efflux is one of the main mechanisms for multidrug resistance in cancers, and 3-Bromopyruvate acts as a promising multidrug resistance reversal compound in our study. To test the ability of 3-Bromopyruvate to overcome P-glycoprotein-mediated multidrug resistance and to explore its mechanisms of multidrug resistance reversal in MCF-7/ADR cells, we evaluate the in vitro and in vivo modulatory activity of this compound.The in vitro and in vivo activity was determined using the MTT assay and human breast cancer xenograft models. The gene and protein expression of P-glycoprotein were determined using real-time polymerase chain reaction and the Western blotting technique, respectively. ABCB-1 bioactivity was tested by fluorescence microscopy, multi-mode microplate reader, and flow cytometry. The intracellular levels of ATP, HK-II, and ATPase activity were based on an assay kit according to the manufacturer's instructions.3-Bromopyruvate treatment led to marked decreases in the IC50 values of selected chemotherapeutic drugs [e.g., doxorubicin (283 folds, paclitaxel (85 folds, daunorubicin (201 folds, and epirubicin (171 folds] in MCF-7/ADR cells. 3-Bromopyruvate was found also to potentiate significantly the antitumor activity of epirubicin against MCF-7/ADR xenografts. The intracellular level of ATP decreased 44%, 46% in the presence of 12.5.25 µM 3-Bromopyruvate, whereas the accumulation of rhodamine 123 and epirubicin (two typical P-glycoprotein substrates in cells was significantly increased. Furthermore, we found that the mRNA and the total protein level of P-glycoprotein were slightly altered by 3-Bromopyruvate. Moreover, the ATPase activity was significantly inhibited when 3-Bromopyruvate was applied.We demonstrated that 3-Bromopyruvate can reverse P-glycoprotein-mediated efflux in MCF-7/ADR cells. Multidrug resistance reversal by 3-Bromopyruvate occurred through at least three approaches, namely, a decrease in the

  18. Comparative tissue pharmacokinetics and efficacy of moxidectin, abamectin and ivermectin in lambs infected with resistant nematodes: Impact of drug treatments on parasite P-glycoprotein expression.

    Science.gov (United States)

    Lloberas, Mercedes; Alvarez, Luis; Entrocasso, Carlos; Virkel, Guillermo; Ballent, Mariana; Mate, Laura; Lanusse, Carlos; Lifschitz, Adrian

    2013-12-01

    The high level of resistance to the macrocyclic lactones has encouraged the search for strategies to optimize their potential as antiparasitic agents. There is a need for pharmaco-parasitological studies addressing the kinetic-dynamic differences between various macrocyclic lactones under standardized in vivo conditions. The current work evaluated the relationship among systemic drug exposure, target tissue availabilities and the pattern of drug accumulation within resistant Haemonchus contortus for moxidectin, abamectin and ivermectin. Drug concentrations in plasma, target tissues and parasites were measured by high performance liquid chromatography. Additionally, the efficacy of the three molecules was evaluated in lambs infected with resistant nematodes by classical parasitological methods. Furthermore, the comparative determination of the level of expression of P-glycoprotein (P-gp2) in H. contortus recovered from lambs treated with each drug was performed by real time PCR. A longer persistence of moxidectin (P ivermectin at day 2 post-treatment. However, the efficacy against H. contortus was 20.1% (ivermectin), 39.7% (abamectin) and 89.6% (moxidectin). Only the ivermectin treatment induced an enhancement on the expression of P-gp2 in the recovered adult H. contortus, reaching higher values at 12 and 24 h post-administration compared to control (untreated) worms. This comparative pharmacological evaluation of three of the most used macrocyclic lactones compounds provides new insights into the action of these drugs.

  19. The multidrug-resistant phenotype associated with overexpression of the new ABC half-transporter, MXR (ABCG2)

    DEFF Research Database (Denmark)

    Litman, Thomas; Brangi, M; Hudson, E;

    2000-01-01

    known as ABCP1 or BCRP. The pharmacodynamics of mitoxantrone and 12 other fluorescent drugs were evaluated by confocal microscopy in four multidrug-resistant human colon (S1) and breast (MCF-7) cancer cell lines. We utilized two sublines, MCF-7 AdVp3000 and S1-M1-80, and detected overexpression of MXR...... by PCR, immunoblot assay and immunohistochemistry. These MXR overexpressing sublines were compared to cell lines with P-glycoprotein- and MRP-mediated resistance. High levels of cross-resistance were observed for mitoxantrone, the anthracyclines, bisantrene and topotecan. Reduced levels of mitoxantrone......, daunorubicin, bisantrene, topotecan, rhodamine 123 and prazosin were observed in the two sublines with high MXR expression. Neither the P-glycoprotein substrates vinblastine, paclitaxel, verapamil and calcein-AM, nor the MRP substrate calcein, were extruded from MCF-7 AdVp3000 and S1-M1-80 cells. Thus...

  20. The ABCs of multidrug resistance in malaria.

    NARCIS (Netherlands)

    Koenderink, J.B.; Kavishe, R.A.; Rijpma, S.R.; Russel, F.G.M.

    2010-01-01

    Expanding drug resistance could become a major problem in malaria treatment, as only a limited number of effective antimalarials are available. Drug resistance has been associated with single nucleotide polymorphisms and an increased copy number of multidrug resistance protein 1 (MDR1), an ATP-bindi

  1. Multidrug resistance reversal in human gastric carcinoma cells by neferine

    Institute of Scientific and Technical Information of China (English)

    Jian-Guo Cao; Xiao-Qing Tang; Shu-Hong Shi

    2004-01-01

    AIM: To investigate the reversal effect of neferine on multidrug resistance in human gastric carcinoma cell line.METHODS: Cells of a human gastric cancer cells line, SGC7901,and its vincristine (VCR) -resistant variant, SGC7901/VCR,were cultivated with or without neferine and/or VCR. The cytotoxic effect of VCR was evaluated by the MTT assay. Cell apoptosis induced by VCR was determined by flow cytometry (FCM). The expression of P-glycoprotein (P-gp) and a multidrug-resistance-associated protein (MRP) in cells was examined by immunofluorescence and FCM.RESULTS: Neferine at the concentration from 2.5 μmol/L to 10 μmol/L had no cytotoxicity to SGC7901 cells, and its variant SGC7901/VCR cells. The IC50 of VCR against SGC7901 and SGC7901/VCR cells was 0.059 μg/mL and 2.32 μg/mL,respectively, indicating that SGC7901/VCR cells were 39 times more resistant to VCR than its parent SGC7 901 cells. After treatment with neferine at concentrations of 2.5, 5 and 10 μmol/L, the IC50 of VCR to SGC7901/VCR cell line decreased to 0.340, 0.128 and 0.053 μg/mL, respectively,thus, increased the chemosensitivity by 6.8-, 18.1- and 43.8-fold, respectively. SGC7901/VCR cells were apoptosis resistant to VCR. Neferine (2.5, 5 and 10 μmol/L) promoted the VCR-induced apoptosis of SGC7901/VCR cells in a dosedependent manner. The expressions of P-gp and MRP were strongly positive in SGC7901/VCR cells, which were significantly down-regulated after treatment with neferine (10 μmol/L)for 24 h.CONCLUSION: Neferine reverses multidrug resistance of human gastric carcinoma SGC7901/VCR cells, which may be associated with the down-regulations of P-gp and MRP expression in SGC701/VCR cells.

  2. MDRl/P-Glycoprotein Function. II. Effect of Hypotonicity and Inhibitors on Cl- Efflux and Volume Regulation

    Science.gov (United States)

    1996-01-01

    ability of MDR1-expressing vs. parental cells multidrug resistance; P-glycoprotein; chloride channel. chlo- to carry out a regulatory volume decrease...NIH/ fibrosis transmembrane conductance regulator ( CFTR ), 3T3MDR murine fibroblasts, FEM-X and FEM-XvMDR which is a Cl- channel (20). The MDR1...the fact chloride channels in volume regulation by T lymphocytes. In: that valinomycin is also an inhibitor of MDR1 trans- Cell Physiology of Blood

  3. Pharmacological, molecular, and cytogenetic analysis of "atypical" multidrug-resistant human leukemic cells.

    Science.gov (United States)

    Beck, W T; Cirtain, M C; Danks, M K; Felsted, R L; Safa, A R; Wolverton, J S; Suttle, D P; Trent, J M

    1987-10-15

    We previously described the cross-resistance patterns and cellular pharmacology of a human leukemic cell line, CEM/VM-1, selected for resistance to the epipodophyllotoxin teniposide (M. K. Danks et al., Cancer Res., 47: 1297-1301, 1987). Compared to CEM/VLB100, which is a well characterized "classic" multidrug-resistant (MDR) cell line, the CEM/VM-1 cells display "atypical" multidrug resistance (at-MDR) in that they are cross-resistant to a wide variety of natural product antitumor drugs, except the Vinca alkaloids, and they are not impaired in their ability to accumulate radiolabeled epipodophyllotoxin. We have extended our characterization of this at-MDR cell line in the present study. In comparison to CEM/VLB100 cells, we found that CEM/VM-1 cells are not cross-resistant to either actinomycin D or colchicine. Verapamil and chloroquine, which enhance the cytotoxicity of vinblastine in CEM/VLB100 cells, had little or no ability to do so in the CEM/VM-1 cells. Membrane vesicles of the two resistant sublines were examined for overexpression of the MDR-associated plasma membrane protein (P-glycoprotein, Mr 170,000 protein, or 180,000 glycoprotein) by photoaffinity labeling with the vinblastine analogue N-(p-azido[3-125I]salicyl)-N'-beta-aminoethylvindesine. We were unable to visualize the MDR-associated protein in the CEM/VM-1 membranes with this photoaffinity probe under conditions in which the P-glycoprotein was readily seen in the membranes of CEM/VLB100 cells. Furthermore, no hybridization of the pMDR1 complementary DNA was seen in slot-blot analyses of the RNA from at-MDR cells, indicating that the mdr gene coding for P-glycoprotein is not overexpressed as is the case in the classic MDR cells. However, cytogenetic analysis indicated that the CEM/VM-1 cells contained an abnormally banded region on chromosome 13q, suggesting that a gene other than mdr may be amplified in these cells. Thus, despite the two cell lines having approximately equal degrees of resistance

  4. Modulation of human multidrug-resistance MDR-1 gene by natural curcuminoids

    Directory of Open Access Journals (Sweden)

    Buddhasukh Duang

    2004-04-01

    Full Text Available Abstract Background Multidrug resistance (MDR is a phenomenon that is often associated with decreased intracellular drug accumulation in patient's tumor cells resulting from enhanced drug efflux. It is related to the overexpression of a membrane protein, P-glycoprotein (Pgp-170, thereby reducing drug cytotoxicity. A variety of studies have tried to find MDR modulators which increase drug accumulation in cancer cells. Methods In this study, natural curcuminoids, pure curcumin, demethoxycurcumin and bisdemethoxycurcumin, isolated from turmeric (Curcuma longa Linn, were compared for their potential ability to modulate the human MDR-1 gene expression in multidrug resistant human cervical carcinoma cell line, KB-V1 by Western blot analysis and RT-PCR. Results Western blot analysis and RT-PCR showed that all the three curcuminoids inhibited MDR-1 gene expression, and bisdemethoxycurcumin produced maximum effect. In additional studies we found that commercial grade curcuminoid (approximately 77% curcumin, 17% demethoxycurcumin and 3% bisdemthoxycurcumin decreased MDR-1 gene expression in a dose dependent manner and had about the same potent inhibitory effect on MDR-1 gene expression as our natural curcuminoid mixtures. Conclusion These results indicate that bisdemethoxycurcumin is the most active of the curcuminoids present in turmeric for modulation of MDR-1 gene. Treatment of drug resistant KB-V1 cells with curcumin increased their sensitivity to vinblastine, which was consistent with a decreased MDR-1 gene product, a P-glycoprotein, on the cell plasma membrane. Although many drugs that prevent the P-glycoprotein function have been reported, this report describes the inhibition of MDR-1 expression by a phytochemical. The modulation of MDR-1 expression may be an attractive target for new chemosensitizing agents.

  5. Detection of multidrug resistance using molecular nuclear technique

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jae Tae; Ahn, Byeong Cheol [School of Medicine, Kyungpook National Univ., Daegu (Korea, Republic of)

    2004-04-01

    Although the outcome of cancer patients after cytotoxic chemotherapy is related diverse mechanisms, multidrug resistance (MDR) for chemotherapeutic drugs due to cellular P-glycoprotein (Pgp) or multidrug-resistance associated protein (MRP) is most important factor in the chemotherapy failure to cancer. A large number of pharmacologic compounds, including verapamil, quinidine, tamoxifen, cyclosporin A and quinolone derivatives have been reported to overcome MDR. Single photon emission computed tomography (SPECT) and positron emission tomography (PET) are available for the detection of Pgp and MRP-mediated transporter. {sup 99}m-Tc-MIBI and other {sup 99}m-Tc-radiopharmaceuticals are substrates for Pgp and MRP, and have been used in clinical studies for tumor imaging, and to visualize blockade of Pgp-mediated transport after modulation of Pgp pump. Colchicine, verapamil and daunorubicin labeled with {sup 11}C have been evaluated for the quantification of Pgp-mediated transport with PET in vivo and reported to be feasible substrates with which to image Pgp function in tumors. Leukotrienes are specific substrates for MRP and N-({sup 11}C)acetyl-leukotriene E4 provides an opportunity to study MRP function non-invasively in vivo. SPECT and PET pharmaceuticals have successfully used to evaluate pharmacologic effects of MDR modulators. Imaging of MDR and reversal of MDR with bioluminescence in a living animal is also evaluated for future clinical trial. We have described recent advances in molecular imaging of MDR and reviewed recent publications regarding feasibility of SPECT and PET imaging to study the functionality of MDR transporters in vivo.

  6. ABC transporters as multidrug resistance mechanisms and the development of chemosensitizers for their reversal

    Directory of Open Access Journals (Sweden)

    Choi Cheol-Hee

    2005-10-01

    Full Text Available Abstract One of the major problems related with anticancer chemotherapy is resistance against anticancer drugs. The ATP-binding cassette (ABC transporters are a family of transporter proteins that are responsible for drug resistance and a low bioavailability of drugs by pumping a variety of drugs out cells at the expense of ATP hydrolysis. One strategy for reversal of the resistance of tumor cells expressing ABC transporters is combined use of anticancer drugs with chemosensitizers. In this review, the physiological functions and structures of ABC transporters, and the development of chemosensitizers are described focusing on well-known proteins including P-glycoprotein, multidrug resistance associated protein, and breast cancer resistance protein.

  7. The multidrug resistance 1 (MDR1) gene polymorphism G-rs3789243-A is not associated with disease susceptibility in Norwegian patients with colorectal adenoma and colorectal cancer; a case control study

    DEFF Research Database (Denmark)

    Andersen, V.; Agerstjerne, L.; Jensen, D.;

    2009-01-01

    Background: Smoking, dietary factors, and alcohol consumption are known life style factors contributing to gastrointestinal carcinogenesis. Genetic variations in carcinogen handling may affect cancer risk. The multidrug resistance 1(MDR1/ABCB1) gene encodes the transport protein P-glycoprotein (a...

  8. Differential role of P-glycoprotein and breast cancer resistance protein in drug distribution into brain, CSF and peripheral nerve tissues in rats.

    Science.gov (United States)

    Huang, Liyue; Li, Xingwen; Roberts, Jonathan; Janosky, Brett; Lin, Min-Hwa Jasmine

    2015-01-01

    1. This study was designed to evaluate how the absence of P-glycoprotein (Pgp, Mdr1a), breast cancer-resistance protein (Bcrp, Abcg2) or both affects drug distribution into sciatic nerves, brain and cerebrospinal fluid (CSF) in rats. 2. Pgp substrate (loperamide), BCRP substrates (dantrolene and proprietary compound X) and dual substrates (imatinib and proprietary compound Y) were well distributed into sciatic nerves with comparable nerve to plasma concentration ratios between wild-type and knockout (KO) rats. 3. Brain exposure increased substantially in Mdr1a(-/-) rats for loperamide and in Mdr1a(-/-)/Abcg2(-/-) rats for imatinib and compound Y, but minimally to modestly in Abcg2(-/-) rats for dantrolene and compound X. The deletion of Mdr1a or Abcg2 alone had little effect on brain distribution of compound Y. 4. While CSF to unbound brain concentration ratio remained ≥3 in the KO animals for dantrolene, compounds X and Y, it was reduced to 1 in the Mdr1a(-/-)/Abcg2(-/-) rats for imatinib. 5. The data indicate that Pgp and Bcrp do not play significant roles in drug distribution into peripheral nerve tissues in rats, while working in concert to regulate brain penetration. Our results further support that CSF concentration may not be a good surrogate for unbound brain concentration of efflux substrates.

  9. Effects of natural nuclear factor-kappa B inhibitors on anticancer drug efflux transporter human P-glycoprotein.

    Science.gov (United States)

    Nabekura, Tomohiro; Hiroi, Takashi; Kawasaki, Tatsuya; Uwai, Yuichi

    2015-03-01

    Drug efflux transporter P-glycoprotein plays an important role in cancer chemotherapy. The nuclear factor-κB (NF-κB) transcription factors play critical roles in development and progression of cancer. In this study, the effects of natural compounds that can inhibit NF-κB activation on the function of P-glycoprotein were investigated using human MDR1 gene-transfected KB/MDR1 cells. The accumulation of daunorubicin or rhodamine 123, fluorescent substrates of P-glycoprotein, in KB/MDR1 cells increased in the presence of caffeic acid phenetyl ester (CAPE), licochalcone A, anacardic acid, celastrol, xanthohumol, magnolol, and honokiol in a concentration-dependent manner. In contrast, lupeol, zerumbone, thymoquinone, emodin, and anethol had no effects. The ATPase activities of P-glycoprotein were stimulated by CAPE, licochalcone A, anacardic acid, celastrol, xanthohumol, magnolol, and honokiol. Tumor necrosis factor (TNF)-α stimulated NF-κB activation was inhibited by CAPE, licochalcone A, anacardic acid, and xanthohumol. KB/MDR1 cells were sensitized to vinblastine cytotoxicity by CAPE, licochalcone A, anacardic acid, xanthohumol, magnolol, and honokiol, showing that these natural NF-κB inhibitors reverse multidrug resistance. These results suggest that natural compounds, such as CAPE, licochalcone A, and anacardic acid, have dual inhibitory effects on the anticancer drug efflux transporter P-glycoprotein and NF-κB activation, and may become useful to enhance the efficacy of cancer chemotherapy.

  10. Marine Natural Products as Models to Circumvent Multidrug Resistance.

    Science.gov (United States)

    Long, Solida; Sousa, Emília; Kijjoa, Anake; Pinto, Madalena M M

    2016-07-08

    Multidrug resistance (MDR) to anticancer drugs is a serious health problem that in many cases leads to cancer treatment failure. The ATP binding cassette (ABC) transporter P-glycoprotein (P-gp), which leads to premature efflux of drugs from cancer cells, is often responsible for MDR. On the other hand, a strategy to search for modulators from natural products to overcome MDR had been in place during the last decades. However, Nature limits the amount of some natural products, which has led to the development of synthetic strategies to increase their availability. This review summarizes the research findings on marine natural products and derivatives, mainly alkaloids, polyoxygenated sterols, polyketides, terpenoids, diketopiperazines, and peptides, with P-gp inhibitory activity highlighting the established structure-activity relationships. The synthetic pathways for the total synthesis of the most promising members and analogs are also presented. It is expected that the data gathered during the last decades concerning their synthesis and MDR-inhibiting activities will help medicinal chemists develop potential drug candidates using marine natural products as models which can deliver new ABC transporter inhibitor scaffolds.

  11. Functional study of the novel multidrug resistance gene HA117 and its comparison to multidrug resistance gene 1

    Directory of Open Access Journals (Sweden)

    Chen Tingfu

    2010-07-01

    Full Text Available Abstract Background The novel gene HA117 is a multidrug resistance (MDR gene expressed by all-trans retinoic acid-resistant HL-60 cells. In the present study, we compared the multidrug resistance of the HA117 with that of the classical multidrug resistance gene 1 (MDR1 in breast cancer cell line 4T1. Methods Transduction of the breast cancer cell line 4T1 with adenoviral vectors encoding the HA117 gene and the green fluorescence protein gene (GFP (Ad-GFP-HA117, the MDR1 and GFP (Ad-GFP-MDR1 or GFP (Ad-GFP was respectively carried out. The transduction efficiency and the multiplicity of infection (MOI were detected by fluorescence microscope and flow cytometry. The transcription of HA117 gene and MDR1 gene were detected by reverse transcription polymerase chain reaction (RT-PCR. Western blotting analysis was used to detect the expression of P-glycoprotein (P-gp but the expression of HA117 could not be analyzed as it is a novel gene and its antibody has not yet been synthesized. The drug-excretion activity of HA117 and MDR1 were determined by daunorubicin (DNR efflux assay. The drug sensitivities of 4T1/HA117 and 4T1/MDR1 to chemotherapeutic agents were detected by Methyl-Thiazolyl-Tetrazolium (MTT assay. Results The transducted efficiency of Ad-GFP-HA117 and Ad-GFP-MDR1 were 75%-80% when MOI was equal to 50. The transduction of Ad-GFP-HA117 and Ad-GFP-MDR1 could increase the expression of HA117 and MDR1. The drug resistance index to Adriamycin (ADM, vincristine (VCR, paclitaxel (Taxol and bleomycin (BLM increased to19.8050, 9.0663, 9.7245, 3.5650 respectively for 4T1/HA117 and 24.2236, 11.0480, 11.3741, 0.9630 respectively for 4T1/MDR1 as compared to the control cells. There were no significant differences in drug sensitivity between 4T1/HA117 and 4T1/MDR1 for the P-gp substrates (ADM, VCR and Taxol (P Conclusions These results confirm that HA117 is a strong MDR gene in both HL-60 and 4T1 cells. Furthermore, our results indicate that the MDR

  12. Integrated assessment of ivermectin pharmacokinetics, efficacy against resistant Haemonchus contortus and P-glycoprotein expression in lambs treated at three different dosage levels.

    Science.gov (United States)

    Alvarez, Luis; Suarez, Gonzalo; Ceballos, Laura; Moreno, Laura; Canton, Candela; Lifschitz, Adrián; Maté, Laura; Ballent, Mariana; Virkel, Guillermo; Lanusse, Carlos

    2015-05-30

    The main goals of the current work were: (a) to assess the ivermectin (IVM) systemic exposure and plasma disposition kinetics after its administration at the recommended dose, x5 and x10 doses to lambs, (b) to compare the clinical efficacy of the same IVM dosages in lambs infected with an IVM-resistant isolate of Haemonchus contortus, and (c) to assess the expression of the transporter protein P-glycoprotein (P-gp) in H. contortus recovered at 14 days after administration of the IVM dose regimens. There were two separated trials where IVM was administered either subcutaneously (SC, Experiment I) or intraruminally (IR, Experiment II). Each experiment involved twenty-four (24) lambs artificially infected with a highly resistant H. contortus isolate. Animals were allocated into 4 groups (n=6) and treated with IVM at either 0.2 (IVM x1), 1 (IVM x5) or 2mg/kg (IVM x10). Plasma samples were collected up to 12 days post-treatment and analysed by HPLC. An untreated-control Group was included to assess the comparative anthelmintic efficacy of the different treatments. The level of expression of Pgp in H. contortus specimens obtained from lambs both untreated and IR treated with the different IVM doses was quantified by real time PCR. Parametric and non-parametric tests were used to compare the statistical significance of the results (PP-gp in adult H. contortus at 14 days post-treatment compared to samples collected from the untreated control group. An enhanced parasite exposure of the drug at the abomasum may explain the improved efficacy against this recalcitrant H. contortus isolate observed only after the IR administration at 5- and 10-fold the IVM therapeutic dosage.

  13. Nuclear multidrug-resistance related protein 1 contributes to multidrug-resistance of mucoepidermoid carcinoma mainly via regulating multidrug-resistance protein 1: a human mucoepidermoid carcinoma cells model and Spearman's rank correlation analysis.

    Directory of Open Access Journals (Sweden)

    Bolei Cai

    Full Text Available BACKGROUND: Multidrug resistance-related protein 1 (MRP1/ABCC1 and multidrug resistance protein 1 (MDR1/P-glycoprotein/ABCB1 are both membrane-bound drug transporters. In contrast to MDR1, MRP1 also transports glutathione (GSH and drugs conjugated to GSH. Due to its extraordinary transport properties, MRP1/ABCC1 contributes to several physiological functions and pathophysiological incidents. We previously found that nuclear translocation of MRP1 contributes to multidrug-resistance (MDR of mucoepidermoid carcinoma (MEC. The present study investigated how MRP1 contributes to MDR in the nuclei of MEC cells. METHODS: Western blot and RT-PCR was carried out to investigate the change of multidrug-resistance protein 1 (MDR1 in MC3/5FU cells after MRP1 was downregulated through RNA interference (RNAi. Immunohistochemistry (IHC staining of 127 cases of MEC tissues was scored with the expression index (EI. The EI of MDR1 and MRP1 (or nuclear MRP1 was analyzed with Spearman's rank correlation analysis. Using multiple tumor tissue assays, the location of MRP1 in other tissues was checked by HIC. Luciferase reporter assays of MDR1 promoter was carried out to check the connection between MRP1 and MDR1 promoter. RESULTS: MRP1 downregulation led to a decreased MDR1 expression in MC3/5FU cells which was caused by decreased activity of MDR1 promoter. IHC study of 127 cases of MEC tissues demonstrated a strong positive correlation between nuclear MRP1 expression and MDR1 expression. Furthermore, IHC study of multiple tumor tissue array sections showed that although nuclear MRP1 widely existed in MEC tissues, it was not found in normal tissues or other tumor tissues. CONCLUSIONS: Our findings indicate that nuclear MRP1 contributes to MDR mainly through regulating MDR1 expression in MEC. And the unique location of MRP1 made it an available target in identifying MEC from other tumors.

  14. The (SNP) of multi-drug resistance 1 protein (MDR1,P-glycoprotein) in Chinese Han population

    Institute of Scientific and Technical Information of China (English)

    DanLI; Guo-liangZHANG; XinWANG; Xiu-yunBU

    2004-01-01

    AIM: To investigate the single nucleotide polymorphism (SNP) of multi-drug resistance 1 protein (MDR1, P-glycoprotein) in the Chinese Han population. METHODS'. DNA was extracted from 200 p,L heparin-anticoagulated whole blood using QIAamp Blood Kit. A polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) was used for the detection of C3435T SNP. The PCR product of 248 bp was digested with

  15. Persistent expression and function of P-glycoprotein on peripheral blood lymphocytes identifies corticosteroid resistance in patients with systemic lupus erythematosus.

    Science.gov (United States)

    Kansal, Amit; Tripathi, Deepak; Rai, Mohit K; Agarwal, Vikas

    2016-02-01

    Corticosteroids (CS) are the mainstay of treatment in systemic lupus erythematosus (SLE) patients. However, some patients have poor response to CS treatment. Among the multiple mechanisms of CS resistance, overexpression of P-glycoprotein (P-gp) on peripheral blood lymphocytes (PBL) may be one of them as this result in efflux of CS from lymphocytes. Thus, we evaluated the role of P-gp protein on PBLs in patients with SLE in its response to CS therapy. SLE patients (n = 42) (fulfilling ACR revised criteria) who were naïve to CS and immunosuppressive drugs were enrolled. Disease activity was assessed using SLE disease activity index (SLEDAI) and expression, and function of P-gp was evaluated by flow cytometry at baseline and after 3 months of therapy with CS. At 3 months, patients with SLEDAI >4 and SLEDAI ≤4 were grouped as nonresponders and responders, respectively. P-gp expression was significantly increased on PBLs of SLE patients as compared to healthy controls (p < 0.001). P-gp expression and function correlated with SLEDAI (r = 0.49, p = 0.005; and r = 0.49, p = 0.001, respectively). P-gp expression and function were not different in responders and nonresponders at baseline. However, at 3 months of CS therapy, P-gp expression and function decreased in responders (p < 0.001 and p < 0.005, respectively), whereas in nonresponders, it remained unchanged. Persistent overexpression and activity of P-gp are associated with poor response to CS in CS naïve patients of SLE.

  16. Influence of multidrug resistance on {sup 18}F-FCH cellular uptake in a glioblastoma model

    Energy Technology Data Exchange (ETDEWEB)

    Vanpouille, Claire; Jeune, Nathalie le; Clotagatide, Anthony; Dubois, Francis [Universite de Lyon, Universite Jean Monnet-Cancer Research Group IFRESIS 143, Saint-Etienne (France); Kryza, David; Janier, Marc [Hospice Civils de Lyon, Quai Des Celestins, CREATIS, UMR CNRS, Lyon (France); Perek, Nathalie [Universite de Lyon, Universite Jean Monnet-Cancer Research Group IFRESIS 143, Saint-Etienne (France); Laboratoire de Biophysique, Faculte de Medecine, Saint-Etienne (France)

    2009-08-15

    Multidrug resistance, aggressiveness and accelerated choline metabolism are hallmarks of malignancy and have motivated the development of new PET tracers like {sup 18}F-FCH, an analogue of choline. Our aim was to study the relationship of multidrug resistance of cultured glioma cell lines and {sup 18}F-FCH tracer uptake. We used an in vitro multidrug-resistant (MDR) glioma model composed of sensitive parental U87MG and derived resistant cells U87MG-CIS and U87MG-DOX. Aggressiveness, choline metabolism and transport were studied, particularly the expression of choline kinase (CK) and high-affinity choline transporter (CHT1). FCH transport studies were assessed in our glioblastoma model. As expected, the resistant cell lines express P-glycoprotein (Pgp), multidrug resistance-associated protein isoform 1 (MRP1) and elevated glutathione (GSH) content and are also more mobile and more invasive than the sensitive U87MG cells. Our results show an overexpression of CK and CHT1 in the resistant cell lines compared to the sensitive cell lines. We found an increased uptake of FCH (in % of uptake per 200,000 cells) in the resistant cells compared to the sensitive ones (U87MG: 0.89{+-}0.14; U87MG-CIS: 1.27{+-}0.18; U87MG-DOX: 1.33{+-}0.13) in line with accelerated choline metabolism and aggressive phenotype. FCH uptake is not influenced by the two ATP-dependant efflux pumps: Pgp and MRP1. FCH would be an interesting probe for glioma imaging which would not be effluxed from the resistant cells by the classic MDR ABC transporters. Our results clearly show that FCH uptake reflects accelerated choline metabolism and is related to tumour aggressiveness and drug resistance. (orig.)

  17. Multidrug resistance: Physiological principles and nanomedical solutions

    NARCIS (Netherlands)

    Kunjachan, S.; Rychlik, B.; Storm, G.; Kiessling, F.; Lammers, T.G.G.M.

    2013-01-01

    Multidrug resistance (MDR) is a pathophysiological phenomenon employed by cancer cells which limits the prolonged and effective use of chemotherapeutic agents. MDR is primarily based on the over-expression of drug efflux pumps in the cellular membrane. Prominent examples of such efflux pumps, which

  18. Drug efflux proteins in multidrug resistant bacteria

    NARCIS (Netherlands)

    vanVeen, HW; Konings, WN

    1997-01-01

    Bacteria contain an array of transport proteins in their cytoplasmic membrane. Many of these proteins play an important role in conferring resistance to toxic compounds. The multidrug efflux systems encountered in prokaryotic cells are very similar to those observed in eukaryotic cells. Therefore, a

  19. P-glycoprotein regulating biphasic insulin secretion in rat pancreatic beta cells

    Institute of Scientific and Technical Information of China (English)

    TANG Yun-zhao; LI Dai-qing; SUN Fu-jun; LI Li; YU De-min

    2009-01-01

    Background A 65-kD mdr1(multi-drug resistance protein 1,P-glycoprotein)-like protein has been suggested to be the regulatory protein to the chloride channel protein 3(CIC-3)mediating insulin granules acidification and release in mouse pancreatic beta cells.But the protein has not been deeply investigated.In this study,we identified existence of the 65-kda protein in rat islets and preliminarily explored its biological functions.Methods Total RNAs of rat kidneys served as positive controls,and pancreas,islets and INS-1 cells were extracted for reverse-transcript PCR(RT-PCR),respectively.The cDNAs were run with specific primers selected from the mRNA of abcblb encoding P-glycoprotein.All PCR products were visualized in agarose gel electrophoresis and sequenced.Homogenates of rat islets and INS-1 cells were applied to SDS-PAGE.P-glycoprotein was detected by a specific monoclonal antibody,C219.Biphasic insulin release was measured in static incubations of rat islets with radioimmunology assay.Results Compared with positive control,expression of the P-glycoprotein mRNA segments were detected in the islets,INS-1 cells and pancreas.Sequence analysis confirmed that the PCR products were matched with mRNA of P-glycoprotein.A 65-kda protein was recognized by the antibody in the islets homogenate but not in that of INS-1 cells in Western-blotting.Instead,the homogenate of INS-1 cells contained a 160-kda protein recognized by the antibody.Insulin secretion of rat islets were stimulated by high glucose(16.7mmol/L),and showed biphasic curve during 60-minute incubation.After co-incubation with cyclosporine A(CsA),specific inhibitor to P-glycoprotein,the second phase of insulin secretion was reduced significantly while the first phase was not influenced.Conclusions The 65-kda protein expressed in rat islets is most likely a mini-P-glycoprotein.It may play a key role regulating biphasic insulin release.

  20. Primary disseminated extrapulmonary multidrug resistant tuberculosis

    Directory of Open Access Journals (Sweden)

    S K Das

    2012-01-01

    Full Text Available Disseminated tuberculosis is a common mode of presentation of tuberculosis in patients both with and without HIV/AIDS in India. However, primary multidrug resistance in disseminated tuberculosis involving only the extrapulmonary sites in an immunocompetent adult is rare. Here, we report a case of a 19-year-old man who had disseminated tuberculosis involving left pleura, pericardium, peritoneum and intraabdominal lymph nodes. He was initially taking WHO category I antituberculous drugs, but was not responding in spite of 5 months of chemotherapy. Culture of the pleural biopsy specimen grew Mycobacterium tuberculosis which was resistant to isoniazid and rifampicin. He was put on therapy for multidrug resistant tuberculosis,following 24 months of chemotherapyhe had an uneventful recovery.

  1. [Travellers and multi-drug resistance bacteria].

    Science.gov (United States)

    Takeshita, Nozomi

    2012-02-01

    The number of international travellers has increased. There is enormous diversity in medical backgrounds, purposes of travel, and travelling styles among travellers. Travellers are hospitalized abroad because of exotic and common diseases via medical tourism. This is one way of transporting and importing human bacteria between countries, including multi-drug resistant organisms. In developing countries, the antimicrobial resistance in Shigella sp. and Salmonella sp. have been a problem, because of this trend, the first choice of antibiotics has changed in some countries. Community acquired infections as well as hospital acquired infections with MRSA, multi-drug resistance (MDR) Pseudomonas aeruginosa, and ESBL have been a problem. This review will discuss the risk of MDR bacterial infectious diseases for travellers.

  2. PET imaging of multidrug resistance in tumors using 18F-fluoropaclitaxel.

    Science.gov (United States)

    Kurdziel, Karen A; Kiesewetter, D O

    2010-01-01

    The failure of solid tumors to respond to chemotherapy is a complicated and clinically frustrating issue. The ability to predict which tumors will respond to treatment could reduce the human and monetary costs of cancer therapy by allowing pro-active selection of a chemotherapeutic to which the tumor does not express resistance. PET/CT imaging with a radiolabeled form of paclitaxel, F-18 fluoropaclitaxel (FPAC), may be able to predict the uptake of paclitaxel in solid tumors, and as a substrate of P-glycoprotein, it may also predict which tumors exhibit multidrug resistance (MDR), a phenotype in which tumors fail to respond to a wide variety of chemically unrelated chemotherapeutic agents. This article reviews the synthetic, preclinical and early human data obtained during the development phase of this promising new radiopharmaceutical.

  3. THE ROLE OF MULTIDRUG RESISTANCE ASSOCIATED PROTEIN (MRP) IN THE BLOOD-BRAIN BARRIER AND OPIOID ANALGESIA

    OpenAIRE

    Su, Wendy; Pasternak, Gavril W.

    2013-01-01

    The blood brain barrier protects the brain from circulating compounds and drugs. The ATP-binding cassette (ABC) transporter P-glycoprotein (Pgp) is involved with the barrier, both preventing the influx of agent from the blood into the brain and facilitating the efflux of compounds from the brain into the blood, raising the possibility of a similar role for other transporters. Multidrug resistance associated protein (MRP), a 190 kDa protein similar to Pgp is also ABC transport that has been im...

  4. Chromosomal Instability Confers Intrinsic Multidrug Resistance

    DEFF Research Database (Denmark)

    Lee, Alvin J. X.; Endesfelder, David; Rowan, Andrew J.

    2011-01-01

    their diploid parental cells only with increasing chromosomal heterogeneity and isogenic cell line models of CIN+ displayed multidrug resistance relative to their CIN- parental cancer cell line derivatives. In a meta-analysis of CRC outcome following cytotoxic treatment, CIN+ predicted worse progression......-free or disease-free survival relative to patients with CIN- disease. Our results suggest that stratifying tumor responses according to CIN status should be considered within the context of clinical trials to minimize the confounding effects of tumor CIN status on drug sensitivity. Cancer Res; 71(5); 1858-70. (c......Aneuploidy is associated with poor prognosis in solid tumors. Spontaneous chromosome missegregation events in aneuploid cells promote chromosomal instability (CIN) that may contribute to the acquisition of multidrug resistance in vitro and heighten risk for tumor relapse in animal models...

  5. Study of multidrug resistance and radioresistance

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Yoon Koo; Yoo, Young Do

    1999-04-01

    We investigated the mechanism of 5-FU, adriamycin, radiation resistance in Korean gastric cancer cells. First we investigated the relation between Rb and multidrug resistance. Rb stable transfectants exhibited 5- to 10- fold more resistance to adriamycin than the control cells. These Rb transfectants showed increased MDR1 expression. We also investigated up-regulation in radiation-resistant tumor tissues. HSP27, MRP-8, GST, and NKEF-B were up-regulated in radiation resistant tumor. Expression of NKEF-B was also increased by radiation exposure in Head and Neck cells. These results demonstrated that NKEF-B is a stress response protein and it may have an important role in radiation resistance.

  6. Circumvention of multi-drug resistance of cancer cells by Chinese herbal medicines

    Directory of Open Access Journals (Sweden)

    Lin Ge

    2010-07-01

    Full Text Available Abstract Multi-drug resistance (MDR of cancer cells severely limits therapeutic outcomes. A proposed mechanism for MDR involves the efflux of anti-cancer drugs from cancer cells, primarily mediated by ATP-binding cassette (ABC membrane transporters including P-glycoprotein. This article reviews the recent progress of using active ingredients, extracts and formulae from Chinese medicine (CM in circumventing ABC transporters-mediated MDR. Among the ABC transporters, Pgp is the most extensively studied for its role in MDR reversal effects. While other MDR reversal mechanisms remain unclear, Pgp inhibition is a criterion for further mechanistic study. More mechanistic studies are needed to fully establish the pharmacological effects of potential MDR reversing agents.

  7. Effects of highly purified anthraquinoid compounds from Aloe vera on sensitive and multidrug resistant leukemia cells.

    Science.gov (United States)

    Grimaudo, S; Tolomeo, M; Gancitano, R; Dalessandro, N; Aiello, E

    1997-01-01

    Folk medicine has attributed antitumor properties to preparations from Aloe vera. We have studied the effects of five purified compounds from the plant on human K562 leukemia and on its multidrug resistant (MDR) variant, K562/R. The glycosides aloin A and B, aloesin and aloeresin were devoid of antitumor activity up to 200 mu M concentrations. Only the aglycone aloe emodin produced reproducible antitumor effects, which, interestingly, were more pronounced in the MDR, P-glycoprotein overexpressing, cell line. Its IC50 was in fact 29 mu M in K562 and 10.5 mu M in K562/R. Aloe emodine caused mainly cytostasis and accumulation of the cells in the S and G(2)-M phases of the cell cycle during the first 48 h of treatment. Thereafter, massive cell death ensued. Research on the antitumor activity of compounds extracted from Aloe vera probably deserves continuation.

  8. Regulation of pregnane-X-receptor, CYP3A and P-glycoprotein genes in the PCB-resistant killifish (Fundulus heteroclitus) population from New Bedford Harbor

    Energy Technology Data Exchange (ETDEWEB)

    Gräns, Johanna; Wassmur, Britt; Fernández-Santoscoy, María [Department of Biological and Environmental Sciences, University of Gothenburg, Box 463, SE 405 30 Gothenburg (Sweden); Zanette, Juliano; Woodin, Bruce R.; Karchner, Sibel I. [Biology Department, MS #32, Woods Hole Oceanographic Institution, Woods Hole, MA 02543 (United States); Nacci, Diane E.; Champlin, Denise; Jayaraman, Saro [Office of Research and Development, National Health and Environmental Effects Research Laboratory, Atlantic Ecology Division, United States Environmental Protection Agency, 27 Tarzwell Drive, Narragansett, RI 02882 (United States); Hahn, Mark E.; Stegeman, John J. [Biology Department, MS #32, Woods Hole Oceanographic Institution, Woods Hole, MA 02543 (United States); Celander, Malin C., E-mail: malin.celander@gu.se [Department of Biological and Environmental Sciences, University of Gothenburg, Box 463, SE 405 30 Gothenburg (Sweden)

    2015-02-15

    Highlights: • Basal levels of PXR and Pgp mRNA are lower in liver of fish from NBH than from SC. • Hepatic PXR, CYP3A and Pgp mRNA levels are induced by PCB in fish from NBH. • Both non-dioxin-like and dioxin-like PCBs induce PXR, CYP3A and Pgp in NBH fish. • Branchial PXR and CYP3A mRNA levels are induced by PCB 126 in fish from SC. • There is possible cross-talk between AhR and PXR signaling in killifish. - Abstract: Killifish survive and reproduce in the New Bedford Harbor (NBH) in Massachusetts (MA), USA, a site severely contaminated with polychlorinated biphenyls (PCBs) for decades. Levels of 22 different PCB congeners were analyzed in liver from killifish collected in 2008. Concentrations of dioxin-like PCBs in liver of NBH killifish were ∼400 times higher, and the levels of non-dioxin-like PCBs ∼3000 times higher than in killifish from a reference site, Scorton Creek (SC), MA. The NBH killifish are known to be resistant to the toxicity of dioxin-like compounds and to have a reduced aryl hydrocarbon receptor (AhR) signaling response. Little is known about the responses of these fish to non-dioxin-like PCBs, which are at extraordinarily high levels in NBH fish. In mammals, some non-dioxin-like PCB congeners act through nuclear receptor 1I2, the pregnane-X-receptor (PXR). To explore this pathway in killifish, a PXR cDNA was sequenced and its molecular phylogenetic relationship to other vertebrate PXRs was determined. Killifish were also collected in 2009 from NBH and SC, and after four months in the laboratory they were injected with a single dose of either the dioxin-like PCB 126 (an AhR agonist) or the non-dioxin-like PCB 153 (a mammalian PXR agonist). Gills and liver were sampled three days after injection and transcript levels of genes encoding PXR, cytochrome P450 3A (CYP3A), P-glycoprotein (Pgp), AhR2 and cytochrome P450 1A (CYP1A) were measured by quantitative PCR. As expected, there was little effect of PCB exposure on mRNA expression of

  9. Regulation of pregnane-X-receptor, CYP3A and P-glycoprotein genes in the PCB-resistant killifish (Fundulus heteroclitus) population from New Bedford Harbor.

    Science.gov (United States)

    Gräns, Johanna; Wassmur, Britt; Fernández-Santoscoy, María; Zanette, Juliano; Woodin, Bruce R; Karchner, Sibel I; Nacci, Diane E; Champlin, Denise; Jayaraman, Saro; Hahn, Mark E; Stegeman, John J; Celander, Malin C

    2015-02-01

    Killifish survive and reproduce in the New Bedford Harbor (NBH) in Massachusetts (MA), USA, a site severely contaminated with polychlorinated biphenyls (PCBs) for decades. Levels of 22 different PCB congeners were analyzed in liver from killifish collected in 2008. Concentrations of dioxin-like PCBs in liver of NBH killifish were ∼400 times higher, and the levels of non-dioxin-like PCBs ∼3000 times higher than in killifish from a reference site, Scorton Creek (SC), MA. The NBH killifish are known to be resistant to the toxicity of dioxin-like compounds and to have a reduced aryl hydrocarbon receptor (AhR) signaling response. Little is known about the responses of these fish to non-dioxin-like PCBs, which are at extraordinarily high levels in NBH fish. In mammals, some non-dioxin-like PCB congeners act through nuclear receptor 1I2, the pregnane-X-receptor (PXR). To explore this pathway in killifish, a PXR cDNA was sequenced and its molecular phylogenetic relationship to other vertebrate PXRs was determined. Killifish were also collected in 2009 from NBH and SC, and after four months in the laboratory they were injected with a single dose of either the dioxin-like PCB 126 (an AhR agonist) or the non-dioxin-like PCB 153 (a mammalian PXR agonist). Gills and liver were sampled three days after injection and transcript levels of genes encoding PXR, cytochrome P450 3A (CYP3A), P-glycoprotein (Pgp), AhR2 and cytochrome P450 1A (CYP1A) were measured by quantitative PCR. As expected, there was little effect of PCB exposure on mRNA expression of AhR2 or CYP1A in liver and gills of NBH fish. In NBH fish, but not in SC fish, there was increased mRNA expression of hepatic PXR, CYP3A and Pgp upon exposure to either of the two PCB congeners. However, basal PXR and Pgp mRNA levels in liver of NBH fish were significantly lower than in SC fish. A different pattern was seen in gills, where there were no differences in basal mRNA expression of these genes between the two

  10. Multidrug-resistant breast cancer: current perspectives

    Directory of Open Access Journals (Sweden)

    Martin HL

    2014-01-01

    Full Text Available Heather L Martin,1 Laura Smith,2 Darren C Tomlinson11BioScreening Technology Group, Leeds Institutes of Molecular Medicine, University of Leeds, Leeds, UK; 2Leeds Institute of Cancer and Pathology, University of Leeds, Leeds, UKAbstract: Breast cancer is the most common cancer in women worldwide, and resistance to the current therapeutics, often concurrently, is an increasing clinical challenge. By understanding the molecular mechanisms behind multidrug-resistant breast cancer, new treatments may be developed. Here we review the recent advances in this understanding, emphasizing the common mechanisms underlying resistance to both targeted therapies, notably tamoxifen and trastuzumab, and traditional chemotherapies. We focus primarily on three molecular mechanisms, the phosphatidylinositide 3-kinase/Akt pathway, the role of microRNAs in gene silencing, and epigenetic alterations affecting gene expression, and discuss how these mechanisms can interact in multidrug resistance. The development of therapeutics targeting these mechanisms is also addressed.Keywords: PI3K/Akt, epigenetics, miRNA, ER, HER2, triple negative

  11. What is Multidrug and Extensively Drug Resistant TB?

    Science.gov (United States)

    ... and Extensively Drug Resistant TB? Multidrug-resistant tuberculosis ( MDR TB ) is a very dangerous form of tuberculosis. Some ... TB medicine so that you will not develop MDR TB. Extensively drug-resistant TB ( XDR TB ) is an ...

  12. Doctors Seeing More HIV Patients with Multidrug Resistance

    Science.gov (United States)

    ... html Doctors Seeing More HIV Patients With Multidrug Resistance People resistant to older medication also have problems ... to modern drugs had HIV mutations linked with resistance to older drugs called thymidine analogues. Among patients ...

  13. Multidrug-Resistant Tuberculosis Complicated by Nosocomial Infection with Multidrug-Resistant Enterobacteriaceae

    NARCIS (Netherlands)

    Gröschel, Matthias I; Omansen, Till F; de Lange, Wiel; van der Werf, Tjip S; Lokate, M.; Bathoorn, Erik; Akkerman, Onno W; Stienstra, Ymkje

    2016-01-01

    Treatment of mycobacterial diseases such as tuberculosis (TB) entails long and intense antimicrobial therapy. TB patients are at risk of coinfection with other multidrug-resistant bacteria, such as those from Enterobacteriaceae family, because of antimicrobial selection pressure and nosocomial trans

  14. Human multidrug resistance ABCB and ABCG transporters: participation in a chemoimmunity defense system.

    Science.gov (United States)

    Sarkadi, Balázs; Homolya, László; Szakács, Gergely; Váradi, András

    2006-10-01

    In this review we give an overview of the physiological functions of a group of ATP binding cassette (ABC) transporter proteins, which were discovered, and still referred to, as multidrug resistance (MDR) transporters. Although they indeed play an important role in cancer drug resistance, their major physiological function is to provide general protection against hydrophobic xenobiotics. With a highly conserved structure, membrane topology, and mechanism of action, these essential transporters are preserved throughout all living systems, from bacteria to human. We describe the general structural and mechanistic features of the human MDR-ABC transporters and introduce some of the basic methods that can be applied for the analysis of their expression, function, regulation, and modulation. We treat in detail the biochemistry, cell biology, and physiology of the ABCB1 (MDR1/P-glycoprotein) and the ABCG2 (MXR/BCRP) proteins and describe emerging information related to additional ABCB- and ABCG-type transporters with a potential role in drug and xenobiotic resistance. Throughout this review we demonstrate and emphasize the general network characteristics of the MDR-ABC transporters, functioning at the cellular and physiological tissue barriers. In addition, we suggest that multidrug transporters are essential parts of an innate defense system, the "chemoimmunity" network, which has a number of features reminiscent of classical immunology.

  15. Reversal of MRP7 (ABCC10-mediated multidrug resistance by tariquidar.

    Directory of Open Access Journals (Sweden)

    Yue-Li Sun

    Full Text Available Multidrug resistance protein 7 (MRP7, ABCC10 is a recently discovered member of the ATP-binding cassette (ABC family which are capable of conferring resistance to a variety of anticancer drugs, including taxanes and nucleoside analogs, in vivo. MRP7 is highly expressed in non-small cell lung cancer cells, and Mrp7-KO mice are highly sensitive to paclitaxel, making MRP7 an attractive chemotherapeutic target of non-small cell lung cancer. However, only a few inhibitors of MRP7 are currently identified, with none of them having progressed to clinical trials. We used MRP7-expressing cells to investigate whether tariquidar, a third generation inhibitor of P-glycoprotein, could inhibit MRP7-mediated multidrug resistance (MDR. We found that tariquidar, at 0.1 and 0.3 µM, significantly potentiated the sensitivity of MRP7-transfected HEK293 cells to MRP7 substrates and increased the intracellular accumulation of paclitaxel. We further demonstrated that tariquidar directly impaired paclitaxel efflux and could downregulate MRP7 protein expression in a concentration- and time-dependent manner after prolonged treatment. Our findings suggest that tariquidar, at pharmacologically achievable concentrations, reverses MRP7-mediated MDR through inhibition of MRP7 protein expression and function, and thus represents a promising therapeutic agent in the clinical treatment of chemoresistant cancer patients.

  16. ABC transporters and multidrug resistance in Aspergillus nidulans

    OpenAIRE

    ANDRADE, A. C.

    2000-01-01

    The term multidrug resistance (MDR) stands for simultaneous cellular resistance to chemically unrelated toxicants and is often associated with overproduction of multidrug-efflux proteins of the A TP- b inding- c assette (ABC) superfamily. The ABC transporters comprise a large and multifunctional family of proteins. Besides multidrug transporters, the superfamily includes proteins involved in transmembrane transport of various substances such as ions, amino acids, peptides, sugars, vitamins, s...

  17. Salvianolic acid A shows selective cytotoxicity against multidrug-resistant MCF-7 breast cancer cells.

    Science.gov (United States)

    Wang, Xin; Wang, Chunyan; Zhang, Longjiang; Li, Yanjun; Wang, Shouju; Wang, Jiandong; Yuan, Caiyun; Niu, Jia; Wang, Chengsheng; Lu, Guangming

    2015-02-01

    Multidrug resistance (MDR) is a major cause for incurable breast cancer. Salvianolic acid A (SAA), the hydrophilic polyphenolic derivative of Salvia miltiorrhiza Bunge (Danshen/Red Sage), was examined for cytotoxicities to MDR MCF-7 human breast cancer cells and their parental counterparts. We have shown that SAA inhibited proliferation, caused cell cycle arrest at the S phase, and induced apoptosis dose dependently to the two kinds of cancer cells. However, the resistant cells were significantly susceptible to the inhibition of SAA compared with the parental cells. SAA increased the level of reactive oxygen species (ROS) by 6.2-fold in the resistant cells, whereas the level of SAA-induced ROS changed only by 1.6-fold in their parental counterparts. Thus, the data showed that the selective cytotoxicity resulted from the hypersensitivity of the resistant cells to the strongly elevated ROS by SAA. In addition, SAA-triggered apoptosis was associated with increased caspase-3 activity, disrupted mitochondrial membrane potential, downregulated Bcl-2 expression, and upregulated Bax expression in the resistant cells. Moreover, SAA downregulated the level of P-glycoprotein, which was overexpressed in the resistant cells. This indicated that SAA modulated MDR. Furthermore, SAA showed higher antitumor activity than did doxorubicin in xenografts established from the resistant cells. The present work raised a possibility that SAA might be considered a potential choice to overcome MDR for the selective susceptibility of the resistant breast cancer cells to SAA treatment.

  18. ABC transporters and multidrug resistance in Aspergillus nidulans

    NARCIS (Netherlands)

    Andrade, A.C.

    2000-01-01

    The term multidrug resistance (MDR) stands for simultaneous cellular resistance to chemically unrelated toxicants and is often associated with overproduction of multidrug-efflux proteins of the A TP- b inding- c assette (ABC) superfamily. The ABC tr

  19. Nonspecifically enhanced therapeutic effects of vincristine on multidrug-resistant cancers when coencapsulated with quinine in liposomes.

    Science.gov (United States)

    Xu, Yuzhen; Qiu, Liyan

    2015-01-01

    The use of vincristine (VCR) to treat cancer has been limited by its dose-dependent toxicity and development of drug resistance after repeated administrations. In this study, we investigated the mechanism by which quinine hydrochloride (QN) acts as a sensitizer for VCR. Our experiments used three kinds of multidrug-resistant cancer cells and demonstrated that QN worked by inducing intracellular depletion of adenosine triphosphate, increasing adenosine triphosphatase activity, and decreasing P-glycoprotein expression. Based on these results, we designed and prepared a VCR and QN codelivery liposome (VQL) and investigated the effect of coencapsulated QN on the in vitro cytotoxicity of VCR in cells and three-dimensional multicellular tumor spheroids. The antitumor effects of the formulation were also evaluated in multidrug-resistant tumor-bearing mice. The results of this in vivo study indicated that VQL could reverse VCR resistance. In addition, it reduced tumor volume 5.4-fold when compared with other test groups. The data suggest that VQL could be a promising nanoscaled therapeutic agent to overcome multidrug resistance, and may have important clinical implications for the treatment of cancer.

  20. Pumping of drugs by P-glycoprotein

    DEFF Research Database (Denmark)

    Litman, Thomas; Skovsgaard, Torben; Stein, Wilfred D

    2003-01-01

    The apparent inhibition constant, Kapp, for the blockade of P-glycoprotein (P-gp) by four drugs, verapamil, cyclosporin A, XR9576 (tariquidar), and vinblastine, was measured by studying their ability to inhibit daunorubicin and calcein-AM efflux from four strains of Ehrlich cells with different...... levels of drug resistance and P-gp content. For daunorubicin as a transport substrate, Kapp was independent of [P-gp] for verapamil but increased strictly linearly with [P-gp] for vinblastine, cyclosporin A, and XR9576. A theoretical analysis of the kinetics of drug pumping and its reversal shows...... that Kapp for inhibition should increase linearly with the amount of pumps present in the membrane for a reverser that inhibits pumping from the cytoplasmic face. In contrast, if the reverser acts by blocking transport from the outer face, i.e., preemptively, Kapp should be independent of the number...

  1. Differential control of cholesterol and fatty acid biosynthesis in sensitive and multidrug-resistant LoVo tumor cells.

    Science.gov (United States)

    Santini, Maria Teresa; Napolitano, Mariarosaria; Ferrante, Antonella; Rainaldi, Gabriella; Arancia, Giuseppe; Bravo, Elena

    2003-01-01

    Multidrug resistance (MDR) describes the decrease in sensitivity of tumor cells to a wide variety of cytotoxic compounds. Although a central role has been ascribed to the P-glycoprotein (Pgp) pump in MDR, lipids also appear to be extremely important. However, their precise role in MDR is not yet fully understood. It was the aim of the present paper to gain a deeper understanding of intracellular lipid equilibrium in both sensitive and MDR tumor cells. In particular, intracellular cholesterol biosynthesis and cholesterol esterification were examined in LoVo-sensitive and Pgp-overexpressing resistant cells. The data presented seem to suggest that the higher synthesis of cholesteryl ester and triglyceride observed in resistant with respect to wild-type cells is due to a greater production of fatty acids in these cells. The results are discussed in view of the possible roles of sterol regulatory element-binding proteins and Pgp in these phenomena.

  2. Preliminary studies on phenothiazine-mediated reversal of multidrug resistance in mouse lymphoma and COLO 320 cells.

    Science.gov (United States)

    Pajak, Beata; Molnar, Joseph; Engi, Helga; Orzechowski, Arkadiusz

    2005-01-01

    The ability of phenothiazine derivatives to inhibit the transport activity of P-glycoprotein in resistant mouse lymphoma and MDR/COLO 320 cells was studied. A rhodamine 123 efflux from the above-mentioned neoplastic cells in the presence of tested compounds was examined by flow cytometry. Two of the phenothiazine derivatives, namely perphenazine and prochlorperazine dimaleate, proved to be effective inhibitors of the rhodamine efflux. Other tested phenothiazine derivatives (promethazine hydrochloride, oxomemazine, methotrimeprazine maleate, trifluoropromazine hydrochloride, trimeprazine) also modulated the intracellular drug accumulation in both resistant cell lines, however, they exerted additional cytotoxic effects. The differences observed between the effects of the test compounds on intracellular drug accumulation could be the outcome of differences in phenothiazine's chemical structure, which is crucial for drug-cell membrane interactions. The results of this study provide information about a new group of compounds that offer promise in multidrug resistance reversal in tumor cells.

  3. Silencing of P-glycoprotein increases mortality in temephos-treated Aedes aegypti larvae.

    Science.gov (United States)

    Figueira-Mansur, J; Ferreira-Pereira, A; Mansur, J F; Franco, T A; Alvarenga, E S L; Sorgine, M H F; Neves, B C; Melo, A C A; Leal, W S; Masuda, H; Moreira, M F

    2013-12-01

    Re-emergence of vector-borne diseases such as dengue and yellow fever, which are both transmitted by the Aedes aegypti mosquito, has been correlated with insecticide resistance. P-glycoproteins (P-gps) are ATP-dependent efflux pumps that are involved in the transport of substrates across membranes. Some of these proteins have been implicated in multidrug resistance (MDR). In this study, we identified a putative P-glycoprotein in the Ae. aegypti database based on its significantly high identity with Anopheles gambiae, Culex quinquefasciatus, Drosophila melanogaster and human P-gps. The basal ATPase activity of ATP-binding cassette transporters in larvae was significantly increased in the presence of MDR modulators (verapamil and quinidine). An eightfold increase in Ae. aegypti P-gp (AaegP-gp) gene expression was detected in temephos-treated larvae as determined by quantitative PCR. To analyse the potential role of AaegP-gp in insecticide efflux, a temephos larvicide assay was performed in the presence of verapamil. The results showed an increase of 24% in temephos toxicity, which is in agreement with the efflux reversing effect. RNA interference (RNAi)-mediated silencing of the AaegP-gp gene caused a significant increase in temephos toxicity (57%). In conclusion, we have demonstrated for the first time in insects that insecticide-induced P-gp expression can be involved in the modulation of insecticide efflux.

  4. Multiple Drug Transport Pathways through Human P-Glycoprotein.

    Science.gov (United States)

    McCormick, James W; Vogel, Pia D; Wise, John G

    2015-07-21

    P-Glycoprotein (P-gp) is a plasma membrane efflux pump that is commonly associated with therapy resistances in cancers and infectious diseases. P-gp can lower the intracellular concentrations of many drugs to subtherapeutic levels by translocating them out of the cell. Because of the broad range of substrates transported by P-gp, overexpression of P-gp causes multidrug resistance. We reported previously on dynamic transitions of P-gp as it moved through conformations based on crystal structures of homologous ABCB1 proteins using in silico targeted molecular dynamics techniques. We expanded these studies here by docking transport substrates to drug binding sites of P-gp in conformations open to the cytoplasm, followed by cycling the pump through conformations that opened to the extracellular space. We observed reproducible transport of two substrates, daunorubicin and verapamil, by an average of 11-12 Å through the plane of the membrane as P-gp progressed through a catalytic cycle. Methylpyrophosphate, a ligand that should not be transported by P-gp, did not show this movement through P-gp. Drug binding to either of two subsites on P-gp appeared to determine the initial pathway used for drug movement through the membrane. The specific side-chain interactions with drugs within each pathway seemed to be, at least in part, stochastic. The docking and transport properties of a P-gp inhibitor, tariquidar, were also studied. A mechanism of inhibition by tariquidar that involves stabilization of an outward open conformation with tariquidar bound in intracellular loops or at the drug binding domain of P-gp is presented.

  5. Salinomycin overcomes ABC transporter-mediated multidrug and apoptosis resistance in human leukemia stem cell-like KG-1a cells

    Energy Technology Data Exchange (ETDEWEB)

    Fuchs, Dominik [Research Group Molecular Neuro-Oncology, German Cancer Research Center, Im Neuenheimer Feld 280, D-69120 Heidelberg (Germany); Institute of Immunology, University of Heidelberg, Im Neuenheimer Feld 305, D-69120 Heidelberg (Germany); Daniel, Volker; Sadeghi, Mahmoud; Opelz, Gerhard [Institute of Immunology, University of Heidelberg, Im Neuenheimer Feld 305, D-69120 Heidelberg (Germany); Naujokat, Cord, E-mail: cord.naujokat@med.uni-heidelberg.de [Institute of Immunology, University of Heidelberg, Im Neuenheimer Feld 305, D-69120 Heidelberg (Germany)

    2010-04-16

    Leukemia stem cells are known to exhibit multidrug resistance by expression of ATP-binding cassette (ABC) transporters which constitute transmembrane proteins capable of exporting a wide variety of chemotherapeutic drugs from the cytosol. We show here that human promyeloblastic leukemia KG-1a cells exposed to the histone deacetylase inhibitor phenylbutyrate resemble many characteristics of leukemia stem cells, including expression of functional ABC transporters such as P-glycoprotein, BCRP and MRP8. Consequently, KG-1a cells display resistance to the induction of apoptosis by various chemotherapeutic drugs. Resistance to apoptosis induction by chemotherapeutic drugs can be reversed by cyclosporine A, which effectively inhibits the activity of P-glycoprotein and BCRP, thus demonstrating ABC transporter-mediated drug resistance in KG-1a cells. However, KG-1a are highly sensitive to apoptosis induction by salinomycin, a polyether ionophore antibiotic that has recently been shown to kill human breast cancer stem cell-like cells and to induce apoptosis in human cancer cells displaying multiple mechanisms of drug and apoptosis resistance. Whereas KG-1a cells can be adapted to proliferate in the presence of apoptosis-inducing concentrations of bortezomib and doxorubicin, salinomycin does not permit long-term adaptation of the cells to apoptosis-inducing concentrations. Thus, salinomycin should be regarded as a novel and effective agent for the elimination of leukemia stem cells and other tumor cells exhibiting ABC transporter-mediated multidrug resistance.

  6. 锌原卟啉ZnPP Ⅸ对Bel/FU肝癌耐药细胞株p-糖蛋白及化疗敏感性的影响%ZnPP Ⅸ's effect on p-glycoprotein expression and chemosensitivity of drug-resistant hepatic carcinoma cell line

    Institute of Scientific and Technical Information of China (English)

    张隽开; 王忠裕; 巩鹏; 罗海峰; 牟国煜

    2011-01-01

    目的:评估锌原卟啉(ZnPP)Ⅸ对Bel/FU肝癌耐药细胞株P-糖蛋白(p-glycoprotein,p-GP)的影响,探讨ZnPP Ⅸ作为化疗耐药逆转剂可能性及相关作用机制.方法:不同浓度的ZnPP Ⅸ作用于Bel/FU肝癌化疗耐药细胞株,MTT法检测细胞株对化疗药物的半数抑制浓度(IC50)、Western blot检测p-GP表达量、罗丹明潴留试验检测p-GP药物外排功能.结果:ZnPP Ⅸ作用于Bel/FU细胞诱导24 h后,化疗药物IC50值均显著降低,P-GP表达量明显降低(P均<0.01),p-GP药物外排功能减弱.结论:ZnPP Ⅸ可通过影响p-GP蛋白质水平的表达,减弱P-GP药物外排功能,使肝癌耐药细胞株的化疗敏感性降低;ZnPP Ⅸ可作为一种潜在的化疗耐药逆转剂.%Objective: To evaluate ZnPP IX's effect on the expression of p-glycoprotein (P-GP)and the chemosensitivity of drug-resistant hepatic carcinoma Bel/Fu cell line,and to explore the relevant regulating mechanism. Methods: After Bel/FU cells being induced by different gradient concentrations of ZnPP IX for 24 h, MTT assay was carried out to detect the sensitivity of Bel/Fu:P-glycoprotein protein level was determined by Western blot analysis; Rhodamine123 retention fluorescent intensity measured by flow cytometry was used to detect the function of p-GP. Results:After Bel/FU cells being dealt with ZnPP IX for 24 h,there were significant differences in 50% inhibiting concentration (IC50) of chemical drugs between control groups and contrast group. IC50 of control groups decreased obviously. Meanwhile, p-GP protein level expression in the cells of control groups were observably lower than that in contrast group. The curve of Rhodamine123 retention fluorescent intensity in the control cells shift to the right, which indicated that the efflux pump function of p-GP was weakened. Conclusions: ZnPP IX can increase the chemosensitivity of Bel/FU cell line,which relates with its action in down-regulation of P-glycoprotein expression. ZnPP IX may be

  7. Mechanisms of multidrug resistance in cancer.

    Science.gov (United States)

    Gillet, Jean-Pierre; Gottesman, Michael M

    2010-01-01

    The development of multidrug resistance (MDR) to chemotherapy remains a major challenge in the treatment of cancer. Resistance exists against every effective anticancer drug and can develop by numerous mechanisms including decreased drug uptake, increased drug efflux, activation of detoxifying systems, activation of DNA repair mechanisms, evasion of drug-induced apoptosis, etc. In the first part of this chapter, we briefly summarize the current knowledge on individual cellular mechanisms responsible for MDR, with a special emphasis on ATP-binding cassette transporters, perhaps the main theme of this textbook. Although extensive work has been done to characterize MDR mechanisms in vitro, the translation of this knowledge to the clinic has not been crowned with success. Therefore, identifying genes and mechanisms critical to the development of MDR in vivo and establishing a reliable method for analyzing clinical samples could help to predict the development of resistance and lead to treatments designed to circumvent it. Our thoughts about translational research needed to achieve significant progress in the understanding of this complex phenomenon are therefore discussed in a third section. The pleotropic response of cancer cells to chemotherapy is summarized in a concluding diagram.

  8. Ligand and structure-based classification models for Prediction of P-glycoprotein inhibitors

    DEFF Research Database (Denmark)

    Klepsch, Freya; Poongavanam, Vasanthanathan; Ecker, Gerhard Franz

    2014-01-01

    The ABC transporter P-glycoprotein (P-gp) actively transports a wide range of drugs and toxins out of cells, and is therefore related to multidrug resistance and the ADME profile of therapeutics. Thus, development of predictive in silico models for the identification of P-gp inhibitors is of great...... interest in the field of drug discovery and development. So far in-silico P-gp inhibitor prediction was dominated by ligand-based approaches, due to the lack of high-quality structural information about P-gp. The present study aims at comparing the P-gp inhibitor/non-inhibitor classification performance...... an algorithm based on Euclidean distance. Results show that random forest and SVM performed best for classification of P-gp inhibitors and non-inhibitors, correctly predicting 73/75 % of the external test set compounds. Classification based on the docking experiments using the scoring function Chem...

  9. Brain penetration of ivermectin and selamectin in mdr1a,b P-glycoprotein- and bcrp- deficient knockout mice.

    Science.gov (United States)

    Geyer, J; Gavrilova, O; Petzinger, E

    2009-02-01

    P-glycoprotein, which is encoded by the multi-drug resistance gene (MDR1), highly restricts the entry of ivermectin into the brain by an ATP-driven efflux mechanism at the blood-brain barrier. In dogs with a homozygous MDR1 mutation though, ivermectin accumulates in the brain and provokes severe signs of neurotoxicosis and even death. In contrast to ivermectin, selamectin is safer in the treatment of MDR1 mutant dogs, suggesting that selamectin is transported differently by P-glycoprotein across the blood-brain barrier. To test this, we applied selamectin to mdr1-deficient mdr1a,b(-/-) knockout mice and wild-type mice. Brain penetration, organ distribution, and plasma kinetics were analyzed after intravenous, oral, and dermal spot-on application in comparison with ivermectin. We found that in vivo both macrocyclic lactone compounds are substrates of P-glycoprotein and that these strongly accumulate in the brain of mdr1a,b(-/-) knockout mice compared with wild-type mice at therapeutic doses of 12 mg/kg selamectin and 0.2 mg/kg ivermectin. However, selamectin accumulates to a much lesser degree (5-10 times) than ivermectin (36-60 times) in the absence of P-glycoprotein. This could explain the broader margin of safety of selamectin in MDR1 mutant dogs. In liver, kidney, and testes, ivermectin and selamectin accumulated less than four times as much in mdr1a,b mutant mice as in wild-type mice. Breast cancer resistance protein (Bcrp)-deficient bcrp(-/-) knockout mice were also included in the application studies, but showed no differences in brain concentrations or organ distribution of either ivermectin or selamectin compared with wild-type mice. This indicates that Bcrp is not a relevant efflux carrier for these macrocyclic lactone compounds in vivo at the blood-brain barrier.

  10. Curcumin as a Modulator of P-Glycoprotein in Cancer: Challenges and Perspectives

    Directory of Open Access Journals (Sweden)

    Vanessa Lopes-Rodrigues

    2016-11-01

    Full Text Available Multidrug resistance (MDR presents a serious challenge to the efficiency of cancer treatment, and may be associated with the overexpression of drug efflux pumps. P-glycoprotein (P-gp is a drug efflux pump often found overexpressed in cases of acquired MDR. Nevertheless, there are no P-gp inhibitors being used in the current clinical practice, due to toxicity problems, drug interactions, or pharmacokinetic issues. Therefore, it is important to identify novel inhibitors of P-gp activity or expression. Curcumin is a secondary metabolite isolated from the turmeric of Curcuma longa L. which has been associated with several biological activities, particularly P-gp modulatory activity (by inhibiting both P-gp function and expression. However, curcumin shows extensive metabolism and instability, which has justified the recent and intensive search for analogs of curcumin that maintain the P-gp modulatory activity but have enhanced stability. This review summarizes and compares the effects of curcumin and several curcumin analogs on P-glycoprotein function and expression, emphasizing the potential of these molecules for the possible development of safe and effective inhibitors of P-gp to overcome MDR in human cancer.

  11. Curcumin as a Modulator of P-Glycoprotein in Cancer: Challenges and Perspectives

    Science.gov (United States)

    Lopes-Rodrigues, Vanessa; Sousa, Emília; Vasconcelos, M. Helena

    2016-01-01

    Multidrug resistance (MDR) presents a serious challenge to the efficiency of cancer treatment, and may be associated with the overexpression of drug efflux pumps. P-glycoprotein (P-gp) is a drug efflux pump often found overexpressed in cases of acquired MDR. Nevertheless, there are no P-gp inhibitors being used in the current clinical practice, due to toxicity problems, drug interactions, or pharmacokinetic issues. Therefore, it is important to identify novel inhibitors of P-gp activity or expression. Curcumin is a secondary metabolite isolated from the turmeric of Curcuma longa L. which has been associated with several biological activities, particularly P-gp modulatory activity (by inhibiting both P-gp function and expression). However, curcumin shows extensive metabolism and instability, which has justified the recent and intensive search for analogs of curcumin that maintain the P-gp modulatory activity but have enhanced stability. This review summarizes and compares the effects of curcumin and several curcumin analogs on P-glycoprotein function and expression, emphasizing the potential of these molecules for the possible development of safe and effective inhibitors of P-gp to overcome MDR in human cancer. PMID:27834897

  12. Thyroid Hormone and P-Glycoprotein in Tumor Cells

    Directory of Open Access Journals (Sweden)

    Paul J. Davis

    2015-01-01

    Full Text Available P-glycoprotein (P-gp; multidrug resistance pump 1, MDR1; ABCB1 is a plasma membrane efflux pump that when activated in cancer cells exports chemotherapeutic agents. Transcription of the P-gp gene (MDR1 and activity of the P-gp protein are known to be affected by thyroid hormone. A cell surface receptor for thyroid hormone on integrin αvβ3 also binds tetraiodothyroacetic acid (tetrac, a derivative of L-thyroxine (T4 that blocks nongenomic actions of T4 and of 3,5,3′-triiodo-L-thyronine (T3 at αvβ3. Covalently bound to a nanoparticle, tetrac as nanotetrac acts at the integrin to increase intracellular residence time of chemotherapeutic agents such as doxorubicin and etoposide that are substrates of P-gp. This action chemosensitizes cancer cells. In this review, we examine possible molecular mechanisms for the inhibitory effect of nanotetrac on P-gp activity. Mechanisms for consideration include cancer cell acidification via action of tetrac/nanotetrac on the Na+/H+ exchanger (NHE1 and hormone analogue effects on calmodulin-dependent processes and on interactions of P-gp with epidermal growth factor (EGF and osteopontin (OPN, apparently via αvβ3. Intracellular acidification and decreased H+ efflux induced by tetrac/nanotetrac via NHE1 is the most attractive explanation for the actions on P-gp and consequent increase in cancer cell retention of chemotherapeutic agent-ligands of MDR1 protein.

  13. Structure-activity relationship study of novel 2-aminobenzofuran derivatives as P-glycoprotein inhibitors.

    Science.gov (United States)

    Chen, Chien-Yu; Lin, Chin-Min; Lin, Hui-Chang; Huang, Chien-Fu; Lee, Chih-Yu; Si Tou, Tze-Chun; Hung, Chin-Chuan; Chang, Chih-Shiang

    2017-01-05

    Treatment of cancer patients with chemotherapeutic drugs is often associated with the occurrence of tumors with a multidrug resistance (MDR). Furthermore, the relation between overexpression of P-glycoprotein (P-gp) and resistant cancers has been well established. In this study, novel 2-aminobenzofuran derivatives were synthesized and tested for their ability to modulate P-gp mediated multidrug resistance (MDR) in vitro. The most potent compound, 43, increased P-gp inhibitory activity at 5 μM by 11.12-fold and was 3.6-fold stronger than verapamil. Furthermore, 43 can sensitize Flp-In™-293/MDR cells toward vincristine, paclitaxel and doxorubicin by 17.95-fold, 13.68-fold and 26.43-fold at 2.5 μM, respectively. 43 also can sensitize the resistant cancer cell line KBvin toward vincristine, paclitaxel and doxorubicin by 246.43-fold, 38.72-fold and 5.16-fold at 2.5 μM, respectively. In conclusion, important aspects for developing potent P-gp inhibitors have been emphasized in this study, providing a starting point for the further structural optimization of P-gp inhibitors.

  14. Epidemiology of Primary Multidrug-Resistant Tuberculosis, Vladimir Region, Russia.

    Science.gov (United States)

    Ershova, Julia V; Volchenkov, Grigory V; Kaminski, Dorothy A; Somova, Tatiana R; Kuznetsova, Tatiana A; Kaunetis, Natalia V; Cegielski, J Peter; Kurbatova, Ekaterina V

    2015-11-01

    We studied the epidemiology of drug-resistant tuberculosis (TB) in Vladimir Region, Russia, in 2012. Most cases of multidrug-resistant TB (MDR TB) were caused by transmission of drug-resistant strains, and >33% were in patients referred for testing after mass radiographic screening. Early diagnosis of drug resistance is essential for preventing transmission of MDR TB.

  15. The human P-glycoprotein transporter enhances the type I interferon response to Listeria monocytogenes infection.

    Science.gov (United States)

    Sigal, Nadejda; Kaplan Zeevi, Millie; Weinstein, Shiri; Peer, Dan; Herskovits, Anat A

    2015-06-01

    Human multidrug efflux transporters are known for their ability to extrude antibiotics and toxic compounds out of cells, yet accumulating data indicate they have additional functions in diverse physiological processes not related to drug efflux. Here, we show that the human multidrug transporter P-glycoprotein (P-gp) (also named MDR1 and ABCB1) is transcriptionally induced in the monocytic cell line THP-1 upon infection with the human intracellular bacterial pathogen Listeria monocytogenes. Notably, we found that P-gp is important for full activation of the type I interferon response elicited against L. monocytogenes bacteria. Both inhibition of P-gp function by verapamil and inhibition of its transcription using mRNA silencing led to a reduction in the magnitude of the type I response in infected cells. This function of P-gp was specific to type I interferon cytokines elicited against cytosolic replicating bacteria and was not observed in response to cyclic di-AMP (c-di-AMP), a molecule that was shown to be secreted by L. monocytogenes during infection and to trigger type I interferons. Moreover, P-gp was not involved in activation of other proinflammatory cytokines, such as those triggered by vacuolar-restricted L. monocytogenes or lipopolysaccharide (LPS). Taken together, these findings demonstrate a role for P-gp in proper development of an innate immune response against intracellular pathogens, highlighting the complexity in employing therapeutic strategies that involve inhibition of multidrug resistance (MDR) efflux pumps.

  16. Establishment of hepatocellular carcinoma multidrug resistant monoclone cell line HepG2/mdr1

    Institute of Scientific and Technical Information of China (English)

    CHEN Yong-bing; XIE Jian-guo; YANG Jia-yin; YAN Lü-nan; YAN Mao-lin; GONG Jian-ping; XIA Ren-pin; LIU Li-xin; LI Ning; LU Shi-chun; ZHANG Jing-guang; ZENG Dao-bing

    2007-01-01

    Background The multidrug resistance (MDR) associated with the expression of the mdr1 gene and its product P-glycoprotein is a major factor in the prognosis of hepatocellular carcinoma cell (HCC) patients treated with chemotherapy. Our study was to establish a stable HCC MDR cell line where a de novo acquisition of multidrug resistance specifically related to overexpression of a transgenic mdr1.Methods The 4.5-kb mdr1 cDNA obtained from the plasmid pHaMDR1-1 was cloned into the PCI-neo mammalian expression vector, later was transferred by liposome to human hepatocarcinoma cell line HepG2. Then the transfected HepG2 cells resisting G418 were clustered and cultured and the specific fragment of mdr1 cDNA, mRNA and the P-glycoprotein (Pgp) in these HepG2 cells were detected by PCR, RT-PCR and flow cytometry, respectively. The accumulation of the daunorubicin was determinated by flow cytometry simultaneously. The nude mice model of grafting tumour was established by injecting subcutaneously HepG2/mdr1 cells in the right axilla. When the tumour diameter reached 5 mm, adriamycin was injected into peritoneal cavity. The size and growth inhibition of tumour were evaluated.Results The mdr1 expression vector was constructed successfully and the MDR HCC line HepG2/mdr1 developed.The PCR analysis showed that the specific fragment of mdr1 cDNA in HepG2/mdr1 cells, but not in the control group HepG2 cells. Furthermore, the content of the specific fragment of mdr1 mRNA and Pgp expression in HepG2/mdr1 cells were (59.7±7.9)% and (12.28±2.09)%, respectively, compared with (16.9±3.2)% and (3.07±1.06)% in HepG2 cells.In the nude mice HCC model, the tumour genes of both groups were identified. After ADM therapy, the mean size of HepG2 cell tumours was significantly smaller than HepG2/mdr1 cell tumours.Conclusion The approach using the transfer of mdr1 cDNA may be applicable to the development of MDR hepatocarcinoma cell line, whose MDR mechanism is known. This would provide the

  17. Effect of curcumin on multidrug resistance in resistant human gastric carcinoma cell line SGC7901/VCR

    Institute of Scientific and Technical Information of China (English)

    Xiao-qing TANG; Hu BI; Jian-qiang FENG; Jian-guo CAO

    2005-01-01

    Aim: To investigate the reversal effects of curcumin on multidrug resistance (MDR)in a resistant human gastric carcinoma cell line. Methods: The cytotoxic effect of vincristine (VCR) was evaluated by MTT assay. The cell apoptosis induced by VCR was determined by propidium iodide (PI)-stained flow cytometry (FCM) and a morphological assay using acridine orange (AO)/ethidium bromide (EB) dual staining. P-glycoprotein (P-gp) function was demonstrated by the accumulation and efflux of rhodamine123 (Rh123) using FCM. The expression of P-gp and the activation of caspase-3 were measured by FCM using fluorescein isothiocyanate (FITC)-conjugated anti-P-gp and anti-cleaved caspase-3 antibodies, respectively.Results: Curcumin, at concentrations of 5 μmol/L, 10 μmol/L, or 20 μmol/L, had no cytotoxic effect on a parent human gastric carcinoma cell line (SGC7901) or its VCR-resistant variant cell line (SGC7901/VCR). The VCR-IC50 value of the SGC7901/VCR cells was 45 times more than that of the SGC7901cells and the SGC7901/VCR cells showed apoptotic resistance to VCR. SGC7901/VCR cells treated with 5μmol/L, 10 μmol/L, or 20 μmol/L curcumin decreased the IC50 value of VCR and promoted VCR-mediated apoptosis in a dose-dependent manner. Curcumin (10μmol/L) increased Rh 123 accumulation and inhibited the efflux of Rh 123 in S GC7901/VCR cells, but did not change the accumulation and efflux of Rh123 in SGC7901cells. P-gp was overexpressed in SGC7901/VCR cells, whereas it was downregulated after a 24-h treatment with curcumin (10 μmol/L). Resistant cells treated with 1μmol/L VCR alone showed 77% lower levels of caspase-3 activation relative to SGC7901 cells, but the activation of caspase-3 in the resistant cell line increased by 44% when cells were treated with VCR in combination with curcumin.Conclusion: Curcumin can reverse the MDR of the human gastric carcinoma SGC7901/VCR cell line. This might be associated with decreased P-gp function and expression, and the promotion of

  18. Genetic knockdown and pharmacological inhibition of parasite multidrug resistance transporters disrupts egg production in Schistosoma mansoni.

    Directory of Open Access Journals (Sweden)

    Ravi S Kasinathan

    2011-12-01

    Full Text Available P-glycoprotein (Pgp and multidrug resistance-associated proteins (MRPs are ATP-dependent transporters involved in efflux of toxins and xenobiotics from cells. When overexpressed, these transporters can mediate multidrug resistance (MDR in mammalian cells, and changes in Pgp expression and sequence are associated with drug resistance in helminths. In addition to the role they play in drug efflux, MDR transporters are essential components of normal cellular physiology, and targeting them may prove a useful strategy for development of new therapeutics or of compounds that enhance the efficacy of current anthelmintics. We previously showed that expression of Schistosoma mansoni MDR transporters increases in response to praziquantel (PZQ, the current drug of choice against schistosomiasis, and that reduced PZQ sensitivity correlates with higher levels of these parasite transporters. We have also shown that PZQ inhibits transport by SMDR2, a Pgp orthologue from S. mansoni, and that PZQ is a likely substrate of SMDR2. Here, we examine the physiological roles of SMDR2 and SmMRP1 (the S. mansoni orthologue of MRP1 in S. mansoni adults, using RNAi to knock down expression, and pharmacological agents to inhibit transporter function. We find that both types of treatments disrupt parasite egg deposition by worms in culture. Furthermore, administration of different MDR inhibitors to S. mansoni-infected mice results in a reduction in egg burden in host liver. These schistosome MDR transporters therefore appear to play essential roles in parasite egg production, and can be targeted genetically and pharmacologically. Since eggs are responsible for the major pathophysiological consequences of schistosomiasis, and since they are also the agents for transmission of the disease, these results suggest a potential strategy for reducing disease pathology and spread.

  19. Multidrug-resistant tuberculosis in Europe, 2010-2011

    NARCIS (Netherlands)

    Gunther, G.; Leth, F. van; Alexandru, S.; Altet, N.; Avsar, K.; Bang, D.; Barbuta, R.; Bothamley, G.; Ciobanu, A.; Crudu, V.; Davilovits, M.; Dedicoat, M.; Duarte, R.; Gualano, G.; Kunst, H.; Lange, W. de; Leimane, V.; Magis-Escurra Ibanez, C.; McLaughlin, A.M.; Muylle, I.; Polcova, V.; Pontali, E.; Popa, C; Rumetshofer, R.; Skrahina, A.; Solodovnikova, V.; Spinu, V.; Tiberi, S.; Viiklepp, P.; Lange, C.

    2015-01-01

    Drug-resistant Mycobacterium tuberculosis is challenging elimination of tuberculosis (TB). We evaluated risk factors for TB and levels of second-line drug resistance in M. tuberculosis in patients in Europe with multidrug-resistant (MDR) TB. A total of 380 patients with MDR TB and 376 patients with

  20. Multidrug-Resistant Tuberculosis in Europe, 2010-2011

    NARCIS (Netherlands)

    Guenther, Gunar; van Leth, Frank; Alexandru, Sofia; Altet, Neus; Avsar, Korkut; Bang, Didi; Barbuta, Raisa; Bothamley, Graham; Ciobanu, Ana; Crudu, Valeriu; Danilovits, Manfred; Dedicoat, Martin; Duarte, Raquel; Gualano, Gina; Kunst, Heinke; de Lange, Wiel; Leimane, Vaira; Magis-Escurra, Cecile; McLaughlin, Anne-Marie; Muylle, Inge; Polcova, Veronika; Pontalli, Emanuele; Popa, Christina; Rumetshofer, Rudolf; Skrahina, Alena; Solodovnikova, Varvara; Spinu, Victor; Tiberi, Simon; Viiklepp, Piret; Lange, Christoph

    2015-01-01

    Drug-resistant Mycobacterium tuberculosis is challenging elimination of tuberculosis (TB). We evaluated risk factors for TB and levels of second-line drug resistance in M. tuberculosis in patients in Europe with multidrug-resistant (MDR) TB. A total of 380 patients with MDR TB and 376 patients with

  1. Pharmacokinetics of ertapenem in patients with multidrug-resistant tuberculosis

    NARCIS (Netherlands)

    van Rijn, Sander P; van Altena, Richard; Akkerman, Onno W; van Soolingen, Dick; van der Laan, Tridia; de Lange, Wiel C M; Kosterink, Jos G W; van der Werf, Tjip S; Alffenaar, Jan-Willem C

    2016-01-01

    Treatment of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB) is becoming more challenging because of increased levels of drug resistance against second-line TB drugs. One promising group of antimicrobial drugs is carbapenems. Ertapenem is an attractive carbapenem for

  2. The inhibitory effect of pseudolaric acid B on gastric cancer and multidrug resistance via Cox-2/PKC-α/P-gp pathway.

    Directory of Open Access Journals (Sweden)

    Qian Sun

    Full Text Available AIM: To investigate the inhibitory effect of pseudolaric acid B on subcutaneous xenografts of human gastric adenocarcinoma and the underlying molecular mechanisms involved in its multidrug resistance. METHODS: Human gastric adenocarcinoma SGC7901 cells and drug-resistant SGC7901/ADR cells were injected into nude mice to establish a subcutaneous xenograft model. The effects of pseudolaric acid B with or without adriamycin treatment were compared by determining the tumor size and weight. Cyclo-oxygenase-2, protein kinaseC-α and P-glycoprotein expression levels were determined by immunohistochemistry and western blot. RESULTS: Pseudolaric acid B significantly suppressed the tumor growth induced by SGC7901 cells and SGC7901/ADR cells. The combination of pseudolaric acid B and the traditional chemotherapy drug adriamycin exhibited more potent inhibitory effects on the growth of gastric cancer in vivo than treatment with either pseudolaric acid B or adriamycin alone. Protein expression levels of cyclo-oxygenase-2, protein kinaseC-α and P-glycoprotein were inhibited by pseudolaric acid B alone or in combination with adriamycin in SGC7901/ADR cell xenografts. CONCLUSION: Pseudolaric acid B has a significant inhibitory effect and an additive inhibitory effect in combination with adriamycin on the growth of gastric cancer in vivo, which reverses the multidrug resistance of gastric neoplasm to chemotherapy drugs by downregulating the Cox-2/PKC-α/P-gp/mdr1 signaling pathway.

  3. Multidrug resistance-1 in T lymphocytes and natural killer cells of adults with idiopathic thrombocytopenic purpura: effect of prednisone treatment.

    Science.gov (United States)

    López-Karpovitch, Xavier; Graue, Gerardo; Crespo-Solís, Erick; Piedras, Josefa

    2008-07-01

    High P-glycoprotein-mediated multidrug resistance-1 (P-gp/MDR1) activity in lymphocytes from idiopathic thrombocytopenic purpura (ITP) patients may affect disease outcome. ITP treatment includes glucocorticoids that are substrates of P-gp; hence, P-gp functional activity and antigenic expression were assessed by flow cytometry in T and natural killer (NK) cells from ITP patients before and after prednisone therapy. Herein, patients' T and NK cells did not show increased MDR1 functional activity, whereas P-gp antigenic expression was significantly enhanced in both therapy-free and prednisone-treated patients. Prednisone treatment did not significantly modify the function and expression of MDR1 in T and NK cells of ITP patients.

  4. Demethoxycurcumin modulates human P-glycoprotein function via uncompetitive inhibition of ATPase hydrolysis activity.

    Science.gov (United States)

    Teng, Yu-Ning; Hsieh, Yow-Wen; Hung, Chin-Chuan; Lin, Hui-Yi

    2015-01-28

    Curcuminoids are major components of Curcuma longa L., which is widely used as spice in food. This study aimed at identifying whether curcumin, demethoxycurcumin, and bisdemethoxycurcumin could modulate efflux function of human P-glycoprotein and be used as chemosensitizers in cancer treatments. Without altering P-glycoprotein expression levels and conformation, the purified curcuminoids significantly inhibited P-glycoprotein efflux function. In rhodamine 123 efflux and calcein-AM accumulation assays, demethoxycurcumin demonstrated the highest inhibition potency (inhibitory IC50 = 1.56 ± 0.13 μM) among the purified curcuminoids, as well as in the fold of reversal assays. Demethoxycurcumin inhibited P-glycoprotein-mediated ATP hydrolysis under concentrations of P-glycoprotein. These results suggested that demethoxycurcumin may be a potential additive natural product in combination with chemotherapeutic agents in drug-resistant cancers.

  5. Breast cancer resistance protein (BCRP/ABCG2) and P-glycoprotein (P-gp/ABCB1) transport afatinib and restrict its oral availability and brain accumulation.

    Science.gov (United States)

    van Hoppe, Stéphanie; Sparidans, Rolf W; Wagenaar, Els; Beijnen, Jos H; Schinkel, Alfred H

    2017-03-10

    Afatinib is a highly selective, irreversible inhibitor of EGFR and (HER)-2. It is orally administered for the treatment of patients with EGFR mutation-positive types of metastatic NSCLC. We investigated whether afatinib is a substrate for the multidrug efflux transporters ABCB1 and ABCG2 and whether these transporters influence oral availability and brain and other tissue accumulation of afatinib. We used in vitro transport assays to assess human (h)ABCB1-, hABCG2- or murine (m)Abcg2-mediated transport of afatinib. To study the single and combined roles of Abcg2 and Abcb1a/1b in oral afatinib disposition, we used appropriate knockout mouse strains. Afatinib was transported well by hABCB1, hABCG2 and mAbcg2 in vitro. Upon oral administration of afatinib, Abcg2(-/-), Abcb1a/1b(-/-) and Abcb1a/1b(-/-);Abcg2(-/-) mice displayed a 4.2-, 2.4- and 7-fold increased afatinib plasma AUC0-24 compared with wild-type mice. Abcg2-deficient strains also displayed decreased afatinib plasma clearance. At 2h, relative brain accumulation of afatinib was not significantly altered in the single knockout strains, but 23.8-fold increased in Abcb1a/1b(-/-);Abcg2(-/-) mice compared to wild-type mice. Abcg2 and Abcb1a/1b restrict oral availability and brain accumulation of afatinib. Inhibition of these transporters may therefore be of clinical importance for patients with brain (micro)metastases positioned behind an intact blood-brain barrier.

  6. Association between DNA methylation and multidrug resistance in human glioma SHG-44 cells.

    Science.gov (United States)

    Chen, Jin; Xu, Zhong-Ye; Wang, Feng

    2015-01-01

    The aim of the present study was to evaluate the association between DNA methylation and multidrug resistance (MDR) in glioma and identify novel effectors responsible for MDR in human gliomas. An MDR glioma cell line, SGH-44/ADM, was developed using adriamycin (ADM) impulse treatment. Cryopreservation, recovery and withdrawal were performed to evaluate the stability of SGH-44/ADM cells. The adherence rate and cellular morphology were observed by microscopy, and the cell growth curve and doubling time were determined. DNA methylation was analyzed using a methylated DNA immunoprecipitation microarray chip (MeDIP-Chip). The cell cycle, Rh123 ingestion and exudation, and SGH-44/ADM apoptosis were analyzed by flow cytometry. SGH-44/ADM cells showed little difference as compared with parental cells, except that SGH-44/ADM cells were bigger in size with a wizened nucleus. Compared to SGH-44 cells, a larger proportion of SGH-44/ADM cells remained in G1 and S phase, as measured by flow cytometry. The MDR of SGH-44/ADM was associated with the upregulation of multi-drug resistance 1, prostaglandin-endoperoxide synthase 2 (COX-2); protein kinase C α (PKCα); however, the expression of these genes was not associated with DNA methylation. In the MeDIP-Chip analysis, 74 functions were markedly enhanced, and seven significant pathways were observed. Genes including SNAP47, ARRB2, PARD6B, TGFB1, VPS4B and CBLB were identified by gene ontology analysis. The predominant molecular mechanism of MDR in SGH-44/ADM cells was identified as exocytosis and efflux. The expression of COX-2, PKCα and P-glycoprotein (Pgp) was not found to be associated with DNA methylation. Genes including SNAP47, VAMP4 and VAMP3 may serve as the downstream effectors of Pgp, COX-2 or PKCα; however, further experiments are required to verify these observations.

  7. Resistance patterns, prevalence, and predictors of fluoroquinolones resistance in multidrug resistant tuberculosis patients

    Directory of Open Access Journals (Sweden)

    Nafees Ahmad

    2016-02-01

    Full Text Available Abstract Background Fluoroquinolones are the backbone of multidrug resistant tuberculosis treatment regimens. Despite the high burden of multidrug resistant tuberculosis in the country, little is known about drug resistance patterns, prevalence, and predictors of fluoroquinolones resistance among multidrug resistant tuberculosis patients from Pakistan. Objective To evaluate drug resistance patterns, prevalence, and predictors of fluoroquinolones resistance in multidrug resistant tuberculosis patients. Methods This was a cross-sectional study conducted at a programmatic management unit of drug resistant tuberculosis, Lady Reading Hospital Peshawar, Pakistan. Two hundred and forty-three newly diagnosed multidrug resistant tuberculosis patients consecutively enrolled for treatment at study site from January 1, 2012 to July 28, 2013 were included in the study. A standardized data collection form was used to collect patients’ socio-demographic, microbiological, and clinical data. SPSS 16 was used for data analysis. Results High degree of drug resistance (median 5 drugs, range 2–8 was observed. High proportion of patients was resistant to all five first-line anti-tuberculosis drugs (62.6%, and more than half were resistant to second line drugs (55.1%. The majority of the patients were ofloxacin resistant (52.7%. Upon multivariate analysis previous tuberculosis treatment at private (OR = 1.953, p = 0.034 and public private mix (OR = 2.824, p = 0.046 sectors were predictors of ofloxacin resistance. Conclusion The high degree of drug resistance observed, particularly to fluoroquinolones, is alarming. We recommend the adoption of more restrictive policies to control non-prescription sale of fluoroquinolones, its rational use by physicians, and training doctors in both private and public–private mix sectors to prevent further increase in fluoroquinolones resistant Mycobacterium tuberculosis strains.

  8. Sinomenine sensitizes multidrug-resistant colon cancer cells (Caco-2 to doxorubicin by downregulation of MDR-1 expression.

    Directory of Open Access Journals (Sweden)

    Zhen Liu

    Full Text Available Chemoresistance in multidrug-resistant (MDR cells over expressing P-glycoprotein (P-gp encoded by the MDR1 gene, is a major obstacle to successful chemotherapy for colorectal cancer. Previous studies have indicated that sinomenine can enhance the absorption of various P-gp substrates. In the present study, we investigated the effect of sinomenine on the chemoresistance in colon cancer cells and explored the underlying mechanism. We developed multidrug-resistant Caco-2 (MDR-Caco-2 cells by exposure of Caco-2 cells to increasing concentrations of doxorubicin. We identified overexpression of COX-2 and MDR-1 genes as well as activation of the NF-κB signal pathway in MDR-Caco-2 cells. Importantly, we found that sinomenine enhances the sensitivity of MDR-Caco-2 cells towards doxorubicin by downregulating MDR-1 and COX-2 expression through inhibition of the NF-κB signaling pathway. These findings provide a new potential strategy for the reversal of P-gp-mediated anticancer drug resistance.

  9. Multidrug-resistant tuberculosis, Somalia, 2010-2011.

    Science.gov (United States)

    Sindani, Ireneaus; Fitzpatrick, Christopher; Falzon, Dennis; Suleiman, Bashir; Arube, Peter; Adam, Ismail; Baghdadi, Samiha; Bassili, Amal; Zignol, Matteo

    2013-03-01

    In a nationwide survey in 2011, multidrug-resistant tuberculosis (MDR TB) was found in 5.2% and 40.8% of patients with new and previously treated TB, respectively. These levels of drug resistance are among the highest ever documented in Africa and the Middle East. This finding presents a serious challenge for TB control in Somalia.

  10. Carriage and transmission dynamics of multidrug-resistant Enterobacteriaceae

    NARCIS (Netherlands)

    Haverkate, M.R.

    2015-01-01

    Antimicrobial-resistant bacteria cause big problems in health care. Infections with these bacteria are hard to treat and lead to high morbidity, mortality, and costs. In this PhD thesis, carriage and transmission dynamics of multidrug-resistant Enterobacteriaceae have been investigated in various se

  11. Multidrug resistant to extensively drug resistant tuberculosis: What is next?

    Indian Academy of Sciences (India)

    Amita Jain; Pratima Dixit

    2008-11-01

    Drug resistant tuberculosis is a man made problem. While tuberculosis is hundred percent curable, multidrug resistant tuberculosis (MDR-TB) is difficult to treat. Inadequate and incomplete treatment and poor treatment adherence has led to a newer form of drug resistance known as extensively drug resistant tuberculosis (XDR-TB). XDR-TB is defined as tuberculosis caused by Mycobacterium tuberculosis strain, which is resistant to at least rifampicin and isoniazid among the first line anti tubercular drugs (MDR-TB) in addition to resistance to any fluroquinolones and at least one of three injectable second line anti tubercular drugs i.e. amikacin, kanamycin and/or capreomycin. Mismanagement of tuberculosis paves the way to drug resistant tuberculosis. Emergence of XDR-TB is reported world wide. Reported prevalence rates of XDR-TB of total MDR cases are; 6.6% overall worldwide, 6.5% in industrialized countries, 13.6% in Russia and Eastern Europe, 1.5% in Asia, 0.6% in Africa and Middle East and 15.4% in Republic of Korea. Better management and control of tuberculosis specially drug resistant TB by experienced and qualified doctors, access to standard microbiology laboratory, co-morbitidy of HIV and tuberculosis, new anti-TB drug regimens, better diagnostic tests, international standards for second line drugs (SLD)-susceptibility testing, invention of newer anti-tubercular molecules and vaccines and knowing the real magnitude of XDR-TB are some of the important issues to be addressed for effective prevention and management of XDR-TB.

  12. Multi-drug resistance gene (MDR1 and opioid analgesia in horses

    Directory of Open Access Journals (Sweden)

    Natalini Cláudio Corrêa

    2006-01-01

    Full Text Available Opioid absorption in the intestinal tract as well as its effects in the central nervous system is modulated by the P-glycoprotein (P-gp encoded in the Multi-drug Resistance gene (MDR1 also named ATP-binding cassete, subfamily B, member 1 (ABCB1. This MDR1 gene acts as a selective pump. The expression of this protein in humans and rodents inhibits cellular uptake of substrate opioids. The presence of the intestinal iso-enzyme CYP3A4 associated with MDR1 gene decreases the opioid analgesic activity due to an increase in intestinal metabolism, with a predicted intestinal first pass extraction around 20% which significantly influences the oral availability of opioids. In the central nervous system, P-gp expression decreases opioid neuronal uptake diminishing the analgesic effects. It is unknown if horses have the MDR1 gene and P-gp and what are the effects on opioid absorption, metabolism, and analgesia. Identifying the MDR1 gene and P-gp status in horses is of great importance in order to better understand opioid pharmacologic effects in horses.

  13. Multidrug resistance 1 gene variants, pesticide exposure, and increased risk of DNA damage.

    Science.gov (United States)

    Chen, Chun-Chieh; Huang, Chun-Huang; Wu, Man-Tzu Marcie; Chou, Chia-Hsuan; Huang, Chia-Chen; Tseng, Tzu-Yen; Chang, Fang-Yu; Li, Ying-Ti; Tsai, Chun-Cheng; Wang, Tsung-Shing; Wong, Ruey-Hong

    2014-01-01

    The P-glycoprotein, encoded by the multidrug resistance (MDR)1 gene, extrudes fat-soluble compounds to the extracellular environment. However, the DNA damage of pesticides in subjects with genetic variation in MDR1 has not been investigated. In this study, the comet assay was applied to examine the extent of DNA damage in the peripheral blood of 195 fruit growers who had been exposed to pesticides and 141 unexposed controls. The MDR1 polymorphisms were identified. Questionnaires were administered to obtain demographic data and occupational history. Results showed subjects experiencing high (2.14 μm/cell, P pesticide exposure (2.18 μm/cell, P pesticide-exposed groups. Combined analysis revealed that pesticide-exposed fruit growers with MDR1 -129 TT genotype had the greatest DNA damage in the subjects with the combinations of pesticide exposure and MDR1 -129 genotypes. In conclusion, pesticide exposed individuals with susceptible MDR1 -129 genotypes may experience increased risk of DNA damage.

  14. Targeting ABCB1-mediated tumor multidrug resistance by CRISPR/Cas9-based genome editing

    Science.gov (United States)

    Yang, Yang; Qiu, Jian-Ge; Li, Yong; Di, Jin-Ming; Zhang, Wen-Ji; Jiang, Qi-Wei; Zheng, Di-Wei; Chen, Yao; Wei, Meng-Ning; Huang, Jia-Rong; Wang, Kun; Shi, Zhi

    2016-01-01

    The RNA-guided clustered regularly interspaced short palindromic (CRISPR) in combination with a CRISPR-associated nuclease 9 (Cas9) nuclease system is a new rapid and precise technology for genome editing. In the present study, we applied the CRISPR/Cas9 system to target ABCB1 (also named MDR1) gene which encodes a 170 kDa transmembrane glycoprotein (P-glycoprotein/P-gp) transporting multiple types of chemotherapeutic drugs including taxanes, epipodophyllotoxins, vinca alkaloids and anthracyclines out of cells to contribute multidrug resistance (MDR) in cancer cells. Our data showed that knockout of ABCB1 by CRISPR/Cas9 system was succesfully archieved with two target sgRNAs in two MDR cancer cells due to the alteration of genome sequences. Knockout of ABCB1 by CRISPR/Cas9 system significantly enhances the sensitivity of ABCB1 substrate chemotherapeutic agents and the intracellular accumulation of rhodamine 123 and doxorubicin in MDR cancer cells. Although now there are lots of limitations to the application of CRISPR/Cas9 for editing cancer genes in human patients, our study provides valuable clues for the use of the CRISPR/Cas9 technology in the investigation and conquest of cancer MDR. PMID:27725879

  15. A role for multidrug resistance protein 4 (MRP4; ABCC4) in human dendritic cell migration.

    Science.gov (United States)

    van de Ven, Rieneke; Scheffer, George L; Reurs, Anneke W; Lindenberg, Jelle J; Oerlemans, Ruud; Jansen, Gerrit; Gillet, Jean-Pierre; Glasgow, Joel N; Pereboev, Alexander; Curiel, David T; Scheper, Rik J; de Gruijl, Tanja D

    2008-09-15

    The capacity of dendritic cells (DCs) to migrate from peripheral organs to lymph nodes (LNs) is important in the initiation of a T cell-mediated immune response. The ATP-binding cassette (ABC) transporters P-glycoprotein (P-gp; ABCB1) and the multidrug resistance protein 1 (MRP1; ABCC1) have been shown to play a role in both human and murine DC migration. Here we show that a more recently discovered family member, MRP4 (ABCC4), is expressed on both epidermal and dermal human skin DCs and contributes to the migratory capacity of DCs. Pharmacological inhibition of MRP4 activity or down-regulation through RNAi in DCs resulted in reduced migration of DCs from human skin explants and of in vitro generated Langerhans cells. The responsible MRP4 substrate remains to be identified as exogenous addition of MRP4's known substrates prostaglandin E(2), leukotriene B(4) and D(4), or cyclic nucleotides (all previously implicated in DC migration) could not restore migration. This notwithstanding, our data show that MRP4 is an important protein, significantly contributing to human DC migration toward the draining lymph nodes, and therefore relevant for the initiation of an immune response and a possible target for immunotherapy.

  16. Reversal of P-gp-mediated multidrug resistance in colon cancer by cinobufagin.

    Science.gov (United States)

    Yuan, Zeting; Shi, Xiaojing; Qiu, Yanyan; Jia, Tingting; Yuan, Xia; Zou, Yu; Liu, Cheng; Yu, Hui; Yuan, Yuxia; He, Xue; Xu, Ke; Yin, Peihao

    2017-03-01

    Cinobufagin (CBF) is isolated from the skin and posterior auricular glands of the Asiatic toad (Bufo gargarizans). This study investigated the reversal effect of CBF on P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) in colon cancer. The effect of CBF on the cytotoxicity of anticancer drugs in P-gp overexpressing LoVo/ADR, HCT116/L, Cao-2/ADR cells and their parental cells was determined using CCK-8 assay. Apoptosis of anti-cancer drugs and accumulation of doxorubicin (DOX) and Rhodamine 123 (Rho123) in P-gp overexpressing cells were evaluated by flow cytometry. Results indicated that CBF significantly enhanced the sensitivity of P-gp substrate drugs on P-gp overexpressing cells, but had no effect on their parental cells. CBF enhanced the effect of DOX against P-gp-overexpressing LoVo/ADR cell xenografts in nude mice. Moreover, CBF also increased cell apoptosis of chemotherapy agents and intracellular accumulation of DOX and Rho123 in the MDR cells. Further research on the mechanisms revealed non-competitive inhibition of P-gp ATPase activity, but without altering the expression of P-gp. These findings demonstrated that CBF could be further developed into a safe and potent P-gp modulator for combination use with anticancer drugs in cancer chemotherapy.

  17. Multidrug resistance-selective antiproliferative activity of Piper amide alkaloids and synthetic analogues.

    Science.gov (United States)

    Wang, Yue-Hu; Goto, Masuo; Wang, Li-Ting; Hsieh, Kan-Yen; Morris-Natschke, Susan L; Tang, Gui-Hua; Long, Chun-Lin; Lee, Kuo-Hsiung

    2014-10-15

    Twenty-five amide alkaloids (1-25) from Piper boehmeriifolium and 10 synthetic amide alkaloid derivatives (39-48) were evaluated for antiproliferative activity against eight human tumor cell lines, including chemosensitive and multidrug-resistant (MDR) cell lines. The results suggested tumor type-selectivity. 1-[7-(3,4,5-Trimethoxyphenyl)heptanoyl]piperidine (46) exhibited the best inhibitory activity (IC50=4.94 μM) against the P-glycoprotein (P-gp)-overexpressing KBvin MDR sub-line, while it and all other tested compounds, except 9, were inactive (IC50 >40 μM) against MDA-MB-231 and SK-BR-3. Structure-activity relationships (SARs) indicated that (i) 3,4,5-trimethoxy phenyl substitution is critical for selectivity against KBvin, (ii) the 4-methoxy group in this pattern is crucial for antiproliferative activity, (iii) double bonds in the side chain are not needed for activity, and (iv), in arylalkenylacyl amide alkaloids, replacement of an isobutylamino group with pyrrolidin-1-yl or piperidin-1-yl significantly improved activity. Further study on Piper amides is warranted, particularly whether side chain length affects the ability to overcome the MDR cancer phenotype.

  18. Modulation of multidrug resistance 1 expression and function in retinoblastoma cells by curcumin

    Directory of Open Access Journals (Sweden)

    Seethalakshmi Sreenivasan

    2013-01-01

    Full Text Available Objective: To determine the possible interaction of curcumin with P-glycoprotein (P-gp expression and function by in vitro and in silico studies. Materials and Methods: In this study, curcumin was compared for its potential to modulate the expression and function of P-gp in Y79 RB cells by western blot, RT-PCR (reverse transcription polymerase chain reaction and functional assay. Further, in silico molecular modeling and docking simulations were performed to deduce the inhibitory binding mode of curcumin. Results: Western blot and RT-PCR analysis decreased the expression of P-gp in a dose-dependent manner. The effect of curcumin on P-gp function was demonstrated by Rhodamine 123 (Rh123 accumulation and efflux study. Curcumin increased the accumulation of Rh123 and decreased its efflux in retinoblastoma (RB cells. In addition, curcumin inhibited verapamil stimulated ATPase activity and photoaffinity labeling study showed no effect on the binding of 8-azido-ATP-biotin, indicating its interaction at the substrate binding site. Moreover, molecular docking studies concurrently infer the binding of curcumin into the substrate binding site of P-gp with a binding energy of -7.66 kcal/mol. Conclusion: These findings indicate that curcumin suppresses the MDR1 expression and function, and therefore may be useful as modulators of multidrug resistance in RB tumor.

  19. Reversal effect and mechanism of Ginkgo biloba exocarp extracts in multidrug resistance of mice S180 tumor cells

    Science.gov (United States)

    Hu, Bi-Yuan; Gu, Yun-Hao; Cao, Chen-Jie; Wang, Jun; Han, Dong-Dong; Tang, Ying-Chao; Chen, Hua-Sheng; Xu, Aihua

    2016-01-01

    The aim of the present study was to investigate the reversal effect and its related mechanism of Ginkgo biloba exocarp extracts (GBEEs) in obtained multidrug resistance (MDR) of mice S180 tumor cells in vitro and in vivo. In order to simulate the clinical PFC [cis-dichlorodiamineplatinum, cisplatin (DDP) + fluorouracil (FU), FU+cyclophosphamide and cyclophosphamide] scheme, a gradually increasing dose was administered in a phased induction in order to induce S180 cells in vivo and to make them obtain multidrug resistance. The results in vitro demonstrated that GBEE could significantly increase the IC50 of DDP on S180 MDR cells, increase the accumulation of Adriamycin (ADR) and rhodamine 123 (Rho 123), and reduce the efflux of Rho 123 of S180 MDR cells. The results from the in vivo treatment with a combination of GBEE and DDP to S180 MDR ascites tumor in mice demonstrated that each dose of GBEE could effectively reverse the drug-resistance of S180 MDR cells to DDP in order to extend the survival time of mice with ascite tumors and inhibit tumor growth in solid tumor mice. In addition, GBEE effectively inhibited the expression of MDR-1 mRNA and multidrug resistance-associated protein-1 mRNA in S180 MDR cells of ascites tumor in mice and improved the expression levels of cytokines, including interleukin (IL)-3, IL-18 and interferon-γ in the blood serum of S180 MDR tumor-bearing mice. The present study showed that the mechanism of GBEE reversal of MDR may be associated with the inhibition of the functional activity of P-glycoprotein, the downregulation of drug resistance related gene expression of S180 MDR cells and the improvement of the production of related serum cytokines of S180 MDR tumor mice. PMID:27698692

  20. Reversal effect and mechanism of Ginkgo biloba exocarp extracts in multidrug resistance of mice S180 tumor cells.

    Science.gov (United States)

    Hu, Bi-Yuan; Gu, Yun-Hao; Cao, Chen-Jie; Wang, Jun; Han, Dong-Dong; Tang, Ying-Chao; Chen, Hua-Sheng; Xu, Aihua

    2016-10-01

    The aim of the present study was to investigate the reversal effect and its related mechanism of Ginkgo biloba exocarp extracts (GBEEs) in obtained multidrug resistance (MDR) of mice S180 tumor cells in vitro and in vivo. In order to simulate the clinical PFC [cis-dichlorodiamineplatinum, cisplatin (DDP) + fluorouracil (FU), FU+cyclophosphamide and cyclophosphamide] scheme, a gradually increasing dose was administered in a phased induction in order to induce S180 cells in vivo and to make them obtain multidrug resistance. The results in vitro demonstrated that GBEE could significantly increase the IC50 of DDP on S180 MDR cells, increase the accumulation of Adriamycin (ADR) and rhodamine 123 (Rho 123), and reduce the efflux of Rho 123 of S180 MDR cells. The results from the in vivo treatment with a combination of GBEE and DDP to S180 MDR ascites tumor in mice demonstrated that each dose of GBEE could effectively reverse the drug-resistance of S180 MDR cells to DDP in order to extend the survival time of mice with ascite tumors and inhibit tumor growth in solid tumor mice. In addition, GBEE effectively inhibited the expression of MDR-1 mRNA and multidrug resistance-associated protein-1 mRNA in S180 MDR cells of ascites tumor in mice and improved the expression levels of cytokines, including interleukin (IL)-3, IL-18 and interferon-γ in the blood serum of S180 MDR tumor-bearing mice. The present study showed that the mechanism of GBEE reversal of MDR may be associated with the inhibition of the functional activity of P-glycoprotein, the downregulation of drug resistance related gene expression of S180 MDR cells and the improvement of the production of related serum cytokines of S180 MDR tumor mice.

  1. Elevated STAT3 Signaling-Mediated Upregulation of MMP-2/9 Confers Enhanced Invasion Ability in Multidrug-Resistant Breast Cancer Cells

    Directory of Open Access Journals (Sweden)

    Fei Zhang

    2015-10-01

    Full Text Available The development of multidrug resistance greatly impedes effective cancer therapy. Recent advances in cancer research have demonstrated that acquisition of multidrug resistance by cancer cells is usually accompanied by enhanced cell invasiveness. Several lines of evidence indicated that cross activation of other signaling pathways during development of drug resistance may increase invasive potential of multidrug-resistant (MDR cancer cells. However, the accurate mechanism of this process is largely undefined. In this study, to better understand the associated molecular pathways responsible for cancer progression induced by drug resistance, a MDR human breast cancer cell line SK-BR-3/EPR with P-glycoprotein overexpression was established using stepwise long-term exposure to increasing concentration of epirubicin. The SK-BR-3/EPR cell line exhibited decreased cell proliferative activity, but enhanced cell invasive capacity. We showed that the expression of metastasis-related matrix metalloproteinase (MMP-2/9 was elevated in SK-BR-3/EPR cells. Moreover, SK-BR-3/EPR cells showed elevated activation of STAT3. Activation of STAT3 signaling is responsible for enhanced invasiveness of SK-BR-3/EPR cells through upregulation of MMP-2/9. STAT3 is a well-known oncogene and is frequently implicated in tumorigenesis and chemotherapeutic resistance. Our findings augment insight into the mechanism underlying the functional association between MDR and cancer invasiveness.

  2. Elevated STAT3 Signaling-Mediated Upregulation of MMP-2/9 Confers Enhanced Invasion Ability in Multidrug-Resistant Breast Cancer Cells.

    Science.gov (United States)

    Zhang, Fei; Wang, Zhiyong; Fan, Yanling; Xu, Qiao; Ji, Wei; Tian, Ran; Niu, Ruifang

    2015-10-16

    The development of multidrug resistance greatly impedes effective cancer therapy. Recent advances in cancer research have demonstrated that acquisition of multidrug resistance by cancer cells is usually accompanied by enhanced cell invasiveness. Several lines of evidence indicated that cross activation of other signaling pathways during development of drug resistance may increase invasive potential of multidrug-resistant (MDR) cancer cells. However, the accurate mechanism of this process is largely undefined. In this study, to better understand the associated molecular pathways responsible for cancer progression induced by drug resistance, a MDR human breast cancer cell line SK-BR-3/EPR with P-glycoprotein overexpression was established using stepwise long-term exposure to increasing concentration of epirubicin. The SK-BR-3/EPR cell line exhibited decreased cell proliferative activity, but enhanced cell invasive capacity. We showed that the expression of metastasis-related matrix metalloproteinase (MMP)-2/9 was elevated in SK-BR-3/EPR cells. Moreover, SK-BR-3/EPR cells showed elevated activation of STAT3. Activation of STAT3 signaling is responsible for enhanced invasiveness of SK-BR-3/EPR cells through upregulation of MMP-2/9. STAT3 is a well-known oncogene and is frequently implicated in tumorigenesis and chemotherapeutic resistance. Our findings augment insight into the mechanism underlying the functional association between MDR and cancer invasiveness.

  3. Farnesiferol A from Ferula persica and galbanic acid from Ferula szowitsiana inhibit P-glycoprotein-mediated rhodamine efflux in breast cancer cell lines.

    Science.gov (United States)

    Hanafi-Bojd, Mohammad Yahya; Iranshahi, Mehrdad; Mosaffa, Fatemeh; Tehrani, Shahireh Omidvar; Kalalinia, Fatemeh; Behravan, Javad

    2011-09-01

    In multidrug resistance (MDR), cancer cells exposed to anticancer agents develop resistance to a wide variety of chemicals and chemotherapeutic agents. Sesquiterpene coumarins are reported to inhibit P-glycoprotein and/or increase cytotoxicity of anticancer drugs in P-gp-overexpressing cell lines. In the current study, we investigated the effects of galbanic acid (from the roots of Ferula szowitsiana) and farnesiferol A (from the roots of Ferula persica) on functionality of the drug transporter P-glycoprotein (P-gp) using a rhodamine 123 efflux assay in a doxorubicin resistant breast cancer cell line (MCF7/Adr). Compared to verapamil, the well-known inhibitor of P-gp, galbanic acid (5, 10, and 25 µg/mL), significantly inhibited the P-gp activity. In inhibition of the P-gp transporter, farnesiferol A (0.5 µg/mL) was more potent than verapamil at 15 min exposure. Our results indicate that the plant derived sesquiterpene coumarins, farnesiferol A and galbanic acid, may be promising candidates to be considered for further studies on the reversal of multidrug resistance phenotype in chemotherapy of cancer patients.

  4. Linezolid susceptibility in Helicobacter pylori, including strains with multidrug resistance.

    Science.gov (United States)

    Boyanova, Lyudmila; Evstatiev, Ivailo; Gergova, Galina; Yaneva, Penka; Mitov, Ivan

    2015-12-01

    Only a few studies have evaluated Helicobacter pylori susceptibility to linezolid. The aim of the present study was to assess linezolid susceptibility in H. pylori, including strains with double/multidrug resistance. The susceptibility of 53 H. pylori strains was evaluated by Etest and a breakpoint susceptibility testing method. Helicobacter pylori resistance rates were as follows: amoxicillin, 1.9%; metronidazole, 37.7%; clarithromycin, 17.0%; tetracycline, 1.9%; levofloxacin, 24.5%; and linezolid (>4 mg/L), 39.6%. The linezolid MIC50 value was 31.2-fold higher than that of clarithromycin and 10.5-fold higher than that of levofloxacin; however, 4 of 11 strains with double/multidrug resistance were linezolid-susceptible. The MIC range of the oxazolidinone agent was larger (0.125-64 mg/L) compared with those in the previous two reports. The linezolid resistance rate was 2.2-fold higher in metronidazole-resistant strains and in strains resistant to at least one antibiotic compared with the remaining strains. Briefly, linezolid was less active against H. pylori compared with clarithromycin and levofloxacin, and linezolid resistance was linked to resistance to metronidazole as well as to resistance to at least one antibiotic. However, linezolid activity against some strains with double/multidrug resistance may render the agent appropriate to treat some associated H. pylori infections following in vitro susceptibility testing of the strains. Clinical trials are required to confirm this suggestion.

  5. Inhibition of multixenobiotic resistance transporters (MXR) by silver nanoparticles and ions in vitro and in Daphnia magna

    NARCIS (Netherlands)

    Georgantzopoulou, Anastasia; Cambier, Sébastien; Serchi, Tommaso; Kruszewski, Marcin; Balachandran, Yekkuni L.; Grysan, Patrick; Audinot, Jean Nicolas; Ziebel, Johanna; Guignard, Cédric; Gutleb, Arno C.; Murk, Tinka

    2016-01-01

    The P-glycoprotein (P-gp, ABCB1) and multidrug resistance associated protein 1 (MRP1), important members of the ABC (ATP-binding cassette) transporters, protect cells and organisms via efflux of xenobiotics and are responsible for the phenomenon of multidrug or multixenobiotic resistance (MXR). I

  6. Modulating cancer multidrug resistance by sertraline in combination with a nanomedicine.

    Science.gov (United States)

    Drinberg, Velthe; Bitcover, Rivka; Rajchenbach, Wolf; Peer, Dan

    2014-11-28

    Inherent and acquired multiple drug resistance (MDR) to chemotherapeutic drugs is a major obstacle in cancer treatment. The ATP Binding Cassettes (ABC) transporter super family that act as extrusion pumps such as P-glycoprotein and multidrug-resistance-associated-proteins have prominent roles in cancer MDR. One of the most efficient strategies to modulate this active drug efflux from the cells is to physically block the pump proteins and thus change the balance between drug influx and efflux toward an accumulation of drug inside the cell, which eventually cumulates into cell death. MDR modulators (also known as chemosensitizers) were found among drugs approved for non-cancer indications. Yet, toxicity, adverse effects, and poor solubility at doses required for MDR reversal prevent their clinical application. Previous reports have shown that drugs belonging to the selective serotonin reuptake inhibitors (SSRI) family, which are clinically used as antidepressants, can act as effective chemosensitizers both in vitro and in vivo in tumor bearing mouse models. Here, we set out to explore whether sertraline (Zoloft®), a molecule belonging to the SSRI family, can be used as an MDR modulator. Combining sertraline with another FDA approved drug, Doxil® (pegylated liposomal doxorubicin), is expected to enhance the effect of chemotherapy while potentially reducing adverse effects. Our findings reveal that sertraline acts as a pump modulator in cellular models of MDR. In addition, in an aggressive and highly resistant human ovarian xenograft mouse model the use of sertraline in combination with Doxil® generated substantial reduction in tumor progression, with extension of the median survival of tumor-bearing mice. Taken together, our results show that sertraline could act as a clinically relevant cancer MDR inhibitor. Moreover, combining two FDA approved drugs, DOXIL®, which favor the influx of chemotherapy inside the malignant cell with sertraline, which blocks the

  7. Redox active copper chelate overcomes multidrug resistance in T-lymphoblastic leukemia cell by triggering apoptosis.

    Science.gov (United States)

    Ganguly, Avishek; Basu, Soumya; Banerjee, Kaushik; Chakraborty, Paramita; Sarkar, Avijit; Chatterjee, Mitali; Chaudhuri, Soumitra Kumar

    2011-05-01

    Multidrug resistance (MDR) mediated by the over expression of drug efflux protein P-glycoprotein (P-gp) is one of the major impediments to successful treatment of cancer. P-gp acts as an energy-dependent drug efflux pump and reduces the intracellular concentration of structurally unrelated drugs inside the cells. Therefore, there is an urgent need for development of new molecules that are less toxic to normal cell and preferentially effective against drug resistant malignant cells. In this preclinical study we report the apoptotic potential of copper N-(2-hydroxyacetophenone) glycinate (CuNG) on doxorubicin resistant T lymphoblastic leukaemia cells (CEM/ADR5000). To evaluate the cytotoxic effect of CuNG, we used different normal cell lines (NIH 3T3, Chang liver and human PBMC) and cancerous cell lines (CEM/ADR5000, parental sensitive CCRF-CEM, SiHa and 3LL) and conclude that CuNG preferentially kills cancerous cells, especially both leukemic cell types irrespective of their MDR status, while leaving normal cell totally unaffected. Moreover, CuNG involves reactive oxygen species (ROS) for induction of apoptosis in CEM/ADR5000 cells through the intrinsic apoptotic pathway. This is substantiated by our observation that antioxidant N-acetyle-cysteine (NAC) and PEG catalase could completely block ROS generation and, subsequently, abrogates CuNG induced apoptosis. On the other hand, uncomplexed ligand N-(2-hydroxyacetophenone) glycinate (NG) fails to generate a significant amount of ROS and concomitant induction of apoptosis in CEM/ADR5000 cells. Therefore, CuNG induces drug resistant leukemia cells to undergo apoptosis and proves to be a molecule having therapeutic potential to overcome MDR in cancer.

  8. Entamoeba histolytica P-glycoprotein (EhPgp) inhibition, induce trophozoite acidification and enhance programmed cell death.

    Science.gov (United States)

    Medel Flores, Olivia; Gómez García, Consuelo; Sánchez Monroy, Virgina; Villalba Magadaleno, José D'Artagnan; Nader García, Elvira; Pérez Ishiwara, D Guillermo

    2013-11-01

    Programmed cell death (PCD) is induced in Entamoeba histolytica by a variety of stimuli in vitro and in vivo. In mammals, intracellular acidification serves as a global switch for inactivating cellular processes and initiates molecular mechanisms implicated in the destruction of the genome. In contrast, intracellular alkalinization produced by P-glycoprotein overexpression in multidrug-resistant cells has been related to apoptosis resistance. Our previous studies showed that overexpression of E. histolytica P-glycoprotein (PGP) altered chloride-dependent currents and triggered trophozoite swelling, the reverse process of cell shrinkage produced during PCD. Here we showed that antisense inhibition of PGP expression produced a synchronous death of trophozoites and the enhancement of biochemical and morphological characteristics of PCD induced by G418. The nucleus was contracted, and the nuclear membrane was disrupted. Moreover, chromatin was extensively fragmented. Ca(2+) concentration was increased, while the intracellular pH (ipH) was acidified. In contrast, PGP overexpression prevented intracellular acidification and circumvented the apoptotic effect of G418.

  9. Polymorphisms in Plasmodium falciparum chloroquine resistance transporter and multidrug resistance 1 genes

    DEFF Research Database (Denmark)

    Venkatesan, Meera; Gadalla, Nahla B; Stepniewska, Kasia;

    2014-01-01

    Adequate clinical and parasitologic cure by artemisinin combination therapies relies on the artemisinin component and the partner drug. Polymorphisms in the Plasmodium falciparum chloroquine resistance transporter (pfcrt) and P. falciparum multidrug resistance 1 (pfmdr1) genes are associated...

  10. Development and characterization of multidrug resistant human hepatocarcinoma cell line in nude mice

    Institute of Scientific and Technical Information of China (English)

    Bao-Jin Zhai; Ze-Yong Shao; Chun-Liang Zhao; Kai Hu; Feng Wu

    2006-01-01

    AIM: To establish a multidrug resistant (MDR) cell subline from the human hepatocarcinoma cell line (HepG2)in nude mice.METHODS: HepG2 cell cultures were incubated with increasing concentrations of adriamycin (ADM) to develop an ADM-resistant cell subline (HepG2/ADM) with crossresistance to other chemotherapeutic agents. Twenty male athymic BALB/c-nu/nu mice were randomized into HepG2/nude and HepG2/ADM/nude groups (10 in each group). A cell suspension (either HepG2 or HepG2/ADM)was injected subcutaneously into mice in each group.Tumor growth was recorded, and animals were sacrificed 4-5 wk after cell implantation. Tumors were prepared for histology, and viable tumor was dispersed into a single-cell suspension. The IC50 values for a number of chemotherapeutic agents were determined by 2, 3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide inner salt (MTT) assay. Rhodamine-123retention/efflux and the level of resistance-associated proteins were determined by flow cytometry. The mRNA expression of mdr1, mrp and Irp genes was detected using reverse transcriptase polymerase chain reaction (RT-PCR) in HepG2/nude and HepG2/ADM/nude groups.RESULTS: The appearances of HepG2/nude cells were slightly different from those of HepG2/ADM/nude cells.Similar tumor growth curves were determined in both groups. A cross-resistance to ADM, vincristine, cisplatin and 5-fiuorouracil was seen in HepG2/ADM/nude group.The levels of P-glycoprotein and multidrug resistanceassociated proteins were significantly increased. The mRNA expression levels of mdr1, mrp and Irp were higher in HepG2/ADM/nude cells.CONCLUSION: ADM-resistant HepG2 subline in nude mice has a cross resistance to chemotherapeutic drugs.Tt may be used as an in vivo model to investigate the mechanisms of MDR, and explore the targeted approaches to overcoming MDR.

  11. Bacterial Multidrug Efflux Pumps: Much More Than Antibiotic Resistance Determinants

    Science.gov (United States)

    Blanco, Paula; Hernando-Amado, Sara; Reales-Calderon, Jose Antonio; Corona, Fernando; Lira, Felipe; Alcalde-Rico, Manuel; Bernardini, Alejandra; Sanchez, Maria Blanca; Martinez, Jose Luis

    2016-01-01

    Bacterial multidrug efflux pumps are antibiotic resistance determinants present in all microorganisms. With few exceptions, they are chromosomally encoded and present a conserved organization both at the genetic and at the protein levels. In addition, most, if not all, strains of a given bacterial species present the same chromosomally-encoded efflux pumps. Altogether this indicates that multidrug efflux pumps are ancient elements encoded in bacterial genomes long before the recent use of antibiotics for human and animal therapy. In this regard, it is worth mentioning that efflux pumps can extrude a wide range of substrates that include, besides antibiotics, heavy metals, organic pollutants, plant-produced compounds, quorum sensing signals or bacterial metabolites, among others. In the current review, we present information on the different functions that multidrug efflux pumps may have for the bacterial behaviour in different habitats as well as on their regulation by specific signals. Since, in addition to their function in non-clinical ecosystems, multidrug efflux pumps contribute to intrinsic, acquired, and phenotypic resistance of bacterial pathogens, the review also presents information on the search for inhibitors of multidrug efflux pumps, which are currently under development, in the aim of increasing the susceptibility of bacterial pathogens to antibiotics. PMID:27681908

  12. Evaluation of the P-glycoprotein- and breast cancer resistance protein-mediated brain penetration of {sup 11}C-labeled topotecan using small-animal positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Yamasaki, Tomoteru; Fujinaga, Masayuki; Kawamura, Kazunori; Hatori, Akiko; Yui, Joji [Department of Molecular Probes, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555 (Japan); Nengaki, Nobuki; Ogawa, Masanao; Yoshida, Yuichiro [Department of Molecular Probes, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555 (Japan); SHI Accelerator Service, Ltd., Tokyo 141-8686 (Japan); Wakizaka, Hidekatsu [Department of Biophysics, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555 (Japan); Yanamoto, Kazuhiko [Division of Health Sciences, Graduate School of Medicine, Osaka University, Osaka 565-0871 (Japan); Fukumura, Toshimitsu [Department of Molecular Probes, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555 (Japan); Zhang Mingrong, E-mail: zhang@nirs.go.jp [Department of Molecular Probes, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba 263-8555 (Japan)

    2011-07-15

    Introduction: Topotecan (TPT) is a camptothecin derivative and is an anticancer drug working as a topoisomerase-I-specific inhibitor. But TPT cannot penetrate through the blood-brain barrier. In this study, we synthesized a new positron emission tomography (PET) probe, [{sup 11}C]TPT, to evaluate the P-glycoprotein (Pgp)- and breast cancer resistance protein (BCRP)-mediated brain penetration of [{sup 11}C]TPT using small-animal PET. Methods: [{sup 11}C]TPT was synthesized by the reaction of a desmethyl precursor with [{sup 11}C]CH{sub 3}I. In vitro study using [{sup 11}C]TPT was carried out in MES-SA and doxorubicin-resistant MES-SA/Dx5 cells in the presence or absence of elacridar, a specific inhibitor for Pgp and BCRP. The biodistribution of [{sup 11}C]TPT was determined using small-animal PET and the dissection method in mice. Results: The transport of [{sup 11}C]TPT to the extracellular side was determined in MES-SA/Dx5 cells exhibiting the expressions of Pgp and BCRP at high levels. This transport was inhibited by coincubation with elacridar. In Mdr1a/b{sup -/-}Bcrp1{sup -/-} mice, PET results indicated that the brain uptake of [{sup 11}C]TPT was about two times higher than that in wild-type mice. Similarly, the brain penetration of [{sup 11}C]TPT in wild-type mice was increased by treatment with elacridar. The radioactivity in the brain of elacridar-treated mice was maintained at a certain level after the injection of [{sup 11}C]TPT, although the radioactivity in the blood decreased with time. Conclusions: We demonstrated the increase of brain penetration of [{sup 11}C]TPT by deficiency and inhibition of Pgp and BCRP functions using small-animal PET in mice.

  13. Infection by multidrug-resistant Elizabethkingia meningoseptica: case reports

    Directory of Open Access Journals (Sweden)

    Jailton Lobo da Costa Lima

    2014-12-01

    Full Text Available We report two cases of sepsis in critically ill patients in two tertiary care hospitals in Recife-PE, Brazil. The first case is an 87-year-old patient with chronic myeloid leukemia and sepsis; and the second case is a 93-year-old patient with prostate cancer and septic shock caused by multidrug-resistant (MDR Elizabethkingia meningoseptica.

  14. Confronting multidrug-resistant Acinetobacter baumannii: a review.

    Science.gov (United States)

    Neonakis, Ioannis K; Spandidos, Demetrios A; Petinaki, Efthimia

    2011-02-01

    Multidrug-resistant Acinetobacter baumannii (MDR-AB) infections are difficult to treat owing to the extremely limited armamentarium. The present review reports all available treatment options against MDR-AB, including single molecules, combination schemes, and alternative modes of antimicrobial administration. Additionally, a group of recently reported peptides with anti-MDR-AB activity is described.

  15. Antimicrobial activity of peptidomimetics against multidrug-resistant Escherichia coli

    DEFF Research Database (Denmark)

    Jahnsen, Rasmus D; Frimodt-Møller, Niels; Franzyk, Henrik

    2012-01-01

    -lactamase-producing Escherichia coli was assessed by testing an array comprising different types of cationic peptidomimetics obtained by a general monomer-based solid-phase synthesis protocol. Most of the peptidomimetics possessed high to moderate activity toward multidrug-resistant E. coli as opposed to the corresponding...

  16. Invasive Infections with Multidrug-Resistant Yeast Candida auris, Colombia

    Science.gov (United States)

    Morales-López, Soraya E.; Parra-Giraldo, Claudia M.; Ceballos-Garzón, Andrés; Martínez, Heidys P.; Rodríguez, Gerson J.; Álvarez-Moreno, Carlos A.

    2017-01-01

    Candida auris is an emerging multidrug-resistant fungus that causes a wide range of symptoms. We report finding 17 cases of C. auris infection that were originally misclassified but correctly identified 27.5 days later on average. Patients with a delayed diagnosis of C. auris had a 30-day mortality rate of 35.2%. PMID:27983941

  17. Multidrug-Resistant Pathogens in Hospitalized Syrian Children

    Science.gov (United States)

    Kassem, Diana Faour; Hoffmann, Yoav; Shahar, Naama; Ocampo, Smadar; Salomon, Liora; Zonis, Zeev

    2017-01-01

    Since 2013, wounded and ill children from Syria have received treatment in Israel. Screening cultures indicated that multidrug-resistant (MDR) pathogens colonized 89 (83%) of 107 children. For 58% of MDR infections, the pathogen was similar to that identified during screening. MDR screening of these children is valuable for purposes of isolation and treatment. PMID:27618479

  18. Multidrug transporters and antibiotic resistance in Lactococcus lactis

    NARCIS (Netherlands)

    Poelarends, GJ; Mazurkiewicz, P; Konings, WN

    2002-01-01

    The Gram-positive bacterium Lactococcus lactis produces two distinct multidrug transporters, designated LmrA and LmrP, that both confer resistance to a wide variety of cationic lipophilic cytotoxic compounds as well as to many clinically relevant antibiotics. While LmrP is a proton/drug antiporter t

  19. FG020326 Sensitized Multidrug Resistant Cancer Cells to Docetaxel-Mediated Apoptosis via Enhancement of Caspases Activation

    Directory of Open Access Journals (Sweden)

    Li-Wu Fu

    2012-05-01

    Full Text Available Apoptotic resistance is the main obstacle for treating cancer patients with chemotherapeutic drugs. Multidrug resistance (MDR is often characterized by the expression of P-glycoprotein (P-gp, a 170-KD ATP-dependent drug efflux protein. Functional P-gp can confer resistance to activate caspase-8 and -3 dependent apoptosis induced by a range of different stimuli, including tumor necrosis and chemotherapeutic drugs such as docetaxel and vincristine. We demonstrated here that comparison of sensitive KB cells, P-gp positive (P-gp+ve KBv200 cells were extremely resistant to apoptosis induced by docetaxel. FG020326, a pharmacological inhibitor of P-gp function, could enhance concentration-dependently the effect of docetaxel on cell apoptosis and sensitize caspase-8, -9 and -3 activation in P-gp overexpressing KBv200 cells, but not in KB cells. Therefore, the enhancement of caspase-8, -9 and -3 activation induced by docetaxel may be one of the key mechanisms of the reversal of P-gp mediated docetaxel resistance by FG020326.

  20. Horizontal gene transfer—emerging multidrug resistance in hospital bacteria

    Institute of Scientific and Technical Information of China (English)

    SenkaDZIDIC; VladimirBEDEKOVIC

    2003-01-01

    The frequency and spectrum of antibiotic resistant infections have increased worldwide during the past few decades. This increase has been attributed to a combination of microbial characteristics, the selective pressure of antimicrobial use, and social and technical changes that enhance the transmission of resistant organisms. The resistance is acquired by mutational changer or by the acquisition of resistance-encoding genetic material which is transfered from another bacteria. The spread of antibiotic resistance genes may be causally related to the overuse of antibiotics in human health care and in animal feeds, increased use of invasive devices and procedures, a greater number of susceptible hosts, and lapses in infection control practices leading to increased transmission of resistant organisms. The resistance gene sequences are integrated by recombination into several classes of naturally occurring gene expression cassettes and disseminated within the microbial population by horizontal gene transfer mechanisms: transformation, conjugation or transduction. In the hospital, widespread use of antimicrobials in the intensive care units (ICU) and for immunocompromised patients has resulted in the selection of multidrug-resistant organisms. Methicilin-resistant Staphylococci, vancomycin resistant Enterococci and extended-spectrum betalactamase(ESBL) producing Gram negative bacilli are identified as major phoblem in nosocomial infections. Recent surveillance studies have demonstrated trend towares more seriously ill patients suffering from multidrug-resistant nosocomial infections. Emergence of multiresistant bacteria and spread of resistance genes should enforce the aplication of strict prevention strategies, including changes in antibiotic treatment regimens, hygiene measures, infection prevention and control of horizontal nosocomial transmission of organisms.

  1. Multidrug-Resistant Enterococci Lack CRISPR-cas

    OpenAIRE

    Palmer, Kelli L.; Michael S Gilmore

    2010-01-01

    Clustered, regularly interspaced short palindromic repeats (CRISPR) provide bacteria and archaea with sequence-specific, acquired defense against plasmids and phage. Because mobile elements constitute up to 25% of the genome of multidrug-resistant (MDR) enterococci, it was of interest to examine the codistribution of CRISPR and acquired antibiotic resistance in enterococcal lineages. A database was built from 16 Enterococcus faecalis draft genome sequences to identify commonalities and polymo...

  2. Inhibition of P-Glycoprotein and Multidrug Resistance-Associated Protein 2 Regulates the Hepatobiliary Excretion and Plasma Exposure of Thienorphine and Its Glucuronide Conjugate

    Science.gov (United States)

    Kong, Ling-Lei; Shen, Guo-Lin; Wang, Zhi-Yuan; Zhuang, Xiao-Mei; Xiao, Wei-Bin; Yuan, Mei; Gong, Ze-Hui; Li, Hua

    2016-01-01

    Thienorphine (TNP) is a novel partial opioid agonist that has completed phase II clinical evaluation as a promising drug candidate for the treatment of opioid dependence. Previous studies have shown that TNP and its glucuronide conjugate (TNP-G) undergo significant bile excretion. The purpose of this study was to investigate the roles of efflux transporters in regulating biliary excretion and plasma exposure of TNP and TNP-G. An ATPase assay suggested that TNP and TNP-G were substrates of P-gp and MRP2, respectively. The in vitro data from rat hepatocytes showed that bile excretion of TNP and TNP-G was regulated by the P-gp and MRP2 modulators. The accumulation of TNP and TNP-G in HepG2 cells significantly increased by the treatment of mdr1a or MRP2 siRNA for P-gp or MRP2 modulation. In intact rats, the bile excretion, and pharmacokinetic profiles of TNP and TNP-G were remarkably changed with tariquidar and probenecid pretreatment, respectively. Tariquidar increased the Cmax and AUC0-t and decreased MRT and T1/2 of TNP, whereas probenecid decreased the plasma exposure of TNP-G and increased its T1/2. Knockdown P-gp and MRP2 function using siRNA significantly increased the plasma exposure of TNP and TNP-G and reduced their mean retention time in mice. These results indicated the important roles of P-gp and MRP2 in hepatobiliary excretion and plasma exposure of TNP and TNP-G. Inhibition of the efflux transporters may affect the pharmacokinetics of TNP and result in a drug-drug interaction between TNP and the concomitant transporter inhibitor or inducer in clinic. PMID:27555820

  3. Inhibition of P-glycoprotein and multidrug resistance-associated protein 2 regulates the hepatobiliary excretion and plasma exposure of thienorphine and its glucuronide conjugate

    Directory of Open Access Journals (Sweden)

    Ling-Lei Kong

    2016-08-01

    Full Text Available Thienorphine (TNP is a novel partial opioid agonist that has completed phase II clinical evaluation as a promising drug candidate for the treatment of opioid dependence. Previous studies have shown that TNP and its glucuronide conjugate (TNP-G undergo significant bile excretion. The purpose of this study was to investigate the roles of efflux transporters in regulating biliary excretion and plasma exposure of TNP and TNP-G. An ATPase assay suggested that TNP and TNP-G were substrates of P-gp and MRP2, respectively. The in vitro data from rat hepatocytes showed that bile excretion of TNP and TNP-G was regulated by the P-gp and MRP2 modulators. The accumulation of TNP and TNP-G in HepG2 cells significantly increased by the treatment of mdr1a or MRP2 siRNA for P-gp or MRP2 modulation. In intact rats, the bile excretion and pharmacokinetic profiles of TNP and TNP-G were remarkably changed with tariquidar and probenecid pretreatment, respectively. Tariquidar increased the Cmax and AUC0-t and decreased MRT and T1/2 of TNP, whereas probenecid decreased the plasma exposure of TNP-G and increased its T1/2. Knockdown P-gp and MRP2 function using siRNA significantly increased the plasma exposure of TNP and TNP-G and reduced their mean retention time in mice. These results indicated the important roles of P-gp and MRP2 in hepatobiliary excretion and plasma exposure of TNP and TNP-G. Inhibition of the efflux transporters may affect the pharmacokinetics of TNP and result in a drug-drug interaction between TNP and the concomitant transporter inhibitor or inducer in clinic.

  4. P-Glycoprotein/MDR1 Regulates Pokemon Gene Transcription Through p53 Expression in Human Breast Cancer Cells

    Directory of Open Access Journals (Sweden)

    Wei Xu

    2010-08-01

    Full Text Available P-glycoprotein (Pgp, encoded by the multidrug resistance 1 (MDR1 gene, is an efflux transporter and plays an important role in pharmacokinetics. In this study, we demonstrated that the pokemon promoter activity, the pokemon mRNA and protein expression can be significantly inhibited by Pgp. Chromatin immunoprecipitation assay showed that Pgp can bind the pokemon prompter to repress pokemon transcription activity. Furthermore, Pgp regulated pokemon transcription activity through expression of p53 as seen by use of p53 siRNA transfected MCF-7 cells or p53 mutated MDA-MB-231 cells. Moreover, p53 was detected to bind with Pgp in vivo using immunoprecipitation assay. Taken together, we conclude that Pgp can regulate the expression of pokemon through the presence of p53, suggesting that Pgp is a potent regulator and may offer an effective novel target for cancer therapy.

  5. Effect of PSC 833, a potent inhibitor of P-glycoprotein, on the growth of astrocytoma cells in vitro.

    Science.gov (United States)

    Sadanand, V; Kankesan, J; Yusuf, A; Stewart, C; Rutka, J T; Thiessen, J J; Ling, V; Rao, P M; Rajalakshmi, S; Sarma, D S R

    2003-07-30

    Malignant astrocytomas have been found to express P-glycoprotein (Pgp, mdr1 gene product). It was hypothesized that in addition to conferring multidrug resistance, Pgp is intimately associated with the development of astrocytomas. Accordingly, we studied the effect of PSC 833 (PSC, Novartis), a potent inhibitor of Pgp, on the growth of Pgp-expressing astrocytoma cells. The results showed that in all the cell lines tested, PSC (10-60 microM) inhibited the growth as well as induced cell death. Cells exposed to PSC exhibited DNA ladder characteristic of apoptosis. PSC-induced cell death could be reversed by Z-VAD-fmk, a general caspase inhibitor, indicating that PSC-induced cell death was characteristic of caspase-mediated apoptosis. These results suggest a novel therapeutic strategy in the treatment of malignant astrocytomas by inhibitors of Pgp.

  6. Modulation of Bacterial Multidrug Resistance Efflux Pumps of the Major Facilitator Superfamily

    Directory of Open Access Journals (Sweden)

    Sanath Kumar

    2013-01-01

    Full Text Available Bacterial infections pose a serious public health concern, especially when an infectious disease has a multidrug resistant causative agent. Such multidrug resistant bacteria can compromise the clinical utility of major chemotherapeutic antimicrobial agents. Drug and multidrug resistant bacteria harbor several distinct molecular mechanisms for resistance. Bacterial antimicrobial agent efflux pumps represent a major mechanism of clinical resistance. The major facilitator superfamily (MFS is one of the largest groups of solute transporters to date and includes a significant number of bacterial drug and multidrug efflux pumps. We review recent work on the modulation of multidrug efflux pumps, paying special attention to those transporters belonging primarily to the MFS.

  7. Double-transduced MDCKII cells to study human P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2) interplay in drug transport across the blood-brain barrier.

    Science.gov (United States)

    Poller, Birk; Wagenaar, Els; Tang, Seng Chuan; Schinkel, Alfred H

    2011-04-04

    P-glycoprotein (P-gp/ABCB1) and breast cancer resistance protein (BCRP/ABCG2) combination knockout mice display disproportionately increased brain penetration of shared substrates, including topotecan and several tyrosine kinase inhibitors, compared to mice deficient for only one transporter. To better study the interplay of both transporters also in vitro, we generated a transduced polarized MDCKII cell line stably coexpressing substantial levels of human ABCB1 and ABCG2 (MDCKII-ABCB1/ABCG2). Next, we measured concentration-dependent transepithelial transport of topotecan, sorafenib and sunitinib. By blocking either one or both of the transporters simultaneously, using specific inhibitors, we aimed to mimic the ABCB1-ABCG2 interplay at the blood-brain barrier in wild-type, single or combination knockout mice. ABCB1 and ABCG2 contributed to similar extents to topotecan transport, which was only partly saturable. For sorafenib transport, ABCG2 was the major determinant at low concentrations. However, saturation of ABCG2-mediated transport occurred at higher sorafenib concentrations, where ABCB1 was still fully active. Furthermore, sunitinib was transported equally by ABCB1 and ABCG2 at low concentrations, but ABCG2-mediated transport became saturated at lower concentrations than ABCB1-mediated transport. The relative impact of these transporters can thus be affected by the applied drug concentrations. A comparison of the in vitro observed (inverse) transport ratios and cellular accumulation of the drugs at low concentrations with in vivo brain penetration data from corresponding Abcb1a/1b⁻/⁻, Abcg2⁻/⁻ and Abcb1a/1b;Abcg2⁻/⁻ mouse strains revealed very similar qualitative patterns for each of the tested drugs. MDCKII-ABCB1/ABCG2 cells thus present a useful in vitro model to study the interplay of ABCB1 and ABCG2.

  8. Reversal of MDR1 gene-dependent multidrug resistance using short hairpin RNA expression vectors

    Institute of Scientific and Technical Information of China (English)

    GAN Hui-zhu; ZHENG De-ming; ZHANG Gui-zhen; ZHAO Ji-sheng; ZHANG Feng-chun; BU Li-sha; YANG Shao-juan; PIAO Song-lan; DU Zhen-wu; GAO Shen

    2005-01-01

    Background RNA interference using short hairpin RNA (shRNA) can mediate sequence-specific inhibition of gene expression in mammalian cells. A vector-based approach for synthesizing shRNA has been developed recently. Overexpression of P-glycoprotein (P-gp), the MDR1 gene product, confers multidrug resistance (MDR) to cancer cells. In this study, we reversed MDR using shRNA expression vectors in a multidrug-resistant human breast cancer cell line (MCF-7/AdrR). Methods The two shRNA expression vectors were constructed and introduced into MCF-7/AdrR cells. Expression of MDR1 mRNA was assessed by RT-PCR, and P-gp expression was determined by Western Blot and immunocytochemistry. Apoptosis and sensitization of the breast cancer cells to doxorubicin were quantified by flow cytometry and methyl thiazolyl tetrazolium (MTT) assays, respectively. Cellular daunorubicin accumulation was assayed by laser confocal scanning microscopy (LCSM). Statistical significance of differences in mean values was evaluated by Student's t tests. P<0.05 was considered statistically significant.Results In MCF-7/AdrA cells transfected with MDR1-A and MDR1-B shRNA expression vectors, RT-PCR showed that MDR1 mRNA expression was reduced by 40.9% (P<0.05), 30.1% (P<0.01) (transient transfection) and 37.6 % (P<0.05), 28.0% (P<0.01) (stable transfection), respectively. Western Blot and immunocytochemistry showed that P-gp expression was significantly and specifically inhibited. Resistance against doxorubicin was decreased from 162-fold to 109-fold (P<0.05), 54-fold (P<0.01) (transient transfection) and to 108-fold (P<0.05), 50-fold (P<0.01) (stable transfection). Furthermore, shRNA vectors significantly enhanced the cellular daunorubicin accumulation. The combination of shRNA vectors and doxorubicin significantly induced apoptosis in MCF-7/AdrR cells. Conclusions shRNA expression vectors effectively reduce MDR expression in a sustained fashion and can restore the sensitivity of drug-resistant cancer

  9. The B-cell lymphoma 2 (BCL2)-inhibitors, ABT-737 and ABT-263, are substrates for P-glycoprotein

    Energy Technology Data Exchange (ETDEWEB)

    Vogler, Meike, E-mail: mv62@le.ac.uk [MRC Toxicology Unit, University of Leicester, LE1 9HN Leicester (United Kingdom); Dickens, David, E-mail: David.Dickens@liverpool.ac.uk [Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, L69 3GL Liverpool (United Kingdom); Dyer, Martin J.S., E-mail: mjsd1@le.ac.uk [MRC Toxicology Unit, University of Leicester, LE1 9HN Leicester (United Kingdom); Owen, Andrew, E-mail: aowen@liverpool.ac.uk [Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, L69 3GL Liverpool (United Kingdom); Pirmohamed, Munir, E-mail: munirp@liv.ac.uk [Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, L69 3GL Liverpool (United Kingdom); Cohen, Gerald M., E-mail: gmc2@le.ac.uk [MRC Toxicology Unit, University of Leicester, LE1 9HN Leicester (United Kingdom)

    2011-05-06

    Highlights: {yields} The BCL2-inhibitor ABT-263 is a substrate for P-glycoprotein. {yields} Apoptosis is inhibited by P-glycoprotein expression. {yields} Overexpression of P-glycoprotein may contribute to resistance to ABT-263 or ABT-737. -- Abstract: Inhibition of BCL2 proteins is one of the most promising new approaches to targeted cancer therapy resulting in the induction of apoptosis. Amongst the most specific BCL2-inhibitors identified are ABT-737 and ABT-263. However, targeted therapy is often only effective for a limited amount of time because of the occurrence of drug resistance. In this study, the interaction of BCL2-inhibitors with the drug efflux transporter P-glycoprotein was investigated. Using {sup 3}H labelled ABT-263, we found that cells with high P-glycoprotein activity accumulated less drug. In addition, cells with increased P-glycoprotein expression were more resistant to apoptosis induced by either ABT-737 or ABT-263. Addition of tariquidar or verapamil sensitized the cells to BCL2-inhibitor treatment, resulting in higher apoptosis. Our data suggest that the BCL2-inhibitors ABT-737 and ABT-263 are substrates for P-glycoprotein. Over-expression of P-glycoprotein may be, at least partly, responsible for resistance to these BCL2-inhibitors.

  10. Expression polymorphism of the blood-brain barrier component P-glycoprotein (MDR1) in relation to Parkinson's disease.

    Science.gov (United States)

    Furuno, Taku; Landi, Maria-Teresa; Ceroni, Mauro; Caporaso, Neil; Bernucci, Ilaria; Nappi, Giuseppe; Martignoni, Emilia; Schaeffeler, Elke; Eichelbaum, Michel; Schwab, Matthias; Zanger, Ulrich M

    2002-10-01

    Because drug transporters such as P-glycoprotein, the product of the multidrug resistance (MDR1 ) gene, contribute to the function of the blood-brain barrier, we hypothesized that differences in their expression could affect the uptake of neurotoxic xenobiotics, thereby modulating interindividual susceptibility for neurological disorders such as Parkinson's disease. In a pilot case-control study comprising 95 Parkinson's disease patients (25 early-onset patients with onset age T in exon 26, 2677G > T,A in exon 21, and -129T > C in exon 1b. There were no statistically significant associations between any of these polymorphisms and Parkinson's disease. However, a distribution pattern consistent with our hypothesis was observed in that the frequency of the 3435T/T genotype, which had previously been associated with decreased P-glycoprotein expression and function, was highest in the early-onset Parkinson's disease group (36.0%), second-highest in the late-onset Parkinson's disease group (22.9%), and lowest in the control group (18.9%). Furthermore, we confirmed that the MDR1 exon 21 and exon 26 polymorphisms are in significant linkage disequilibrium since the [2677G, 3435C] and [2677T, 3435T] haplotypes were far more frequently observed than expected. In conclusion, MDR1 and other drug transporters represent plausible candidates as Parkinson's disease risk genes. Larger studies are required to confirm this role in the etiology of Parkinson's disease.

  11. Fallopia japonica, a Natural Modulator, Can Overcome Multidrug Resistance in Cancer Cells

    Directory of Open Access Journals (Sweden)

    Safaa Yehia Eid

    2015-01-01

    Full Text Available Resistance of cancer cells to chemotherapy is controlled by the decrease of intracellular drug accumulation, increase of detoxification, and diminished propensity of cancer cells to undergo apoptosis. ATP-binding cassette (ABC membrane transporters with intracellular metabolic enzymes contribute to the complex and unresolved phenomenon of multidrug resistance (MDR. Natural products as alternative medicine have great potential to discover new MDR inhibitors with diverse modes of action. In this study, we characterized several extracts of traditional Chinese medicine (TCM plants (N = 16 for their interaction with ABC transporters, cytochrome P3A4 (CYP3A4, and glutathione-S-transferase (GST activities and their cytotoxic effect on different cancer cell lines. Fallopia japonica (FJ (Polygonaceae shows potent inhibitory effect on CYP3A4 P-glycoprotein activity about 1.8-fold when compared to verapamil as positive control. FJ shows significant inhibitory effect (39.81% compared with the known inhibitor ketoconazole and 100 μg/mL inhibited GST activity to 14 μmol/min/mL. FJ shows moderate cytotoxicity in human Caco-2, HepG-2, and HeLa cell lines; IC50 values were 630.98, 198.80, and 317.37 µg/mL, respectively. LC-ESI-MS were used to identify and quantify the most abundant compounds, emodin, polydatin, and resveratrol, in the most active extract of FJ. Here, we present the prospect of using Fallopia japonica as natural products to modulate the function of ABC drug transporters. We are conducting future study to evaluate the ability of the major active secondary metabolites of Fallopia japonica to modulate MDR and their impact in case of failure of chemotherapy.

  12. Sensitization of multidrug-resistant human cancer cells to Hsp90 inhibitors by down-regulation of SIRT1.

    Science.gov (United States)

    Kim, Hak-Bong; Lee, Su-Hoon; Um, Jee-Hyun; Oh, Won Keun; Kim, Dong-Wan; Kang, Chi-Dug; Kim, Sun-Hee

    2015-11-03

    The effectiveness of Hsp90 inhibitors as anticancer agents was limited in multidrug-resistant (MDR) human cancer cells due to induction of heat shock proteins (Hsps) such as Hsp70/Hsp27 and P-glycoprotein (P-gp)-mediated efflux. In the present study, we showed that resistance to Hsp90 inhibitors of MDR human cancer cells could be overcome with SIRT1 inhibition. SIRT1 knock-down or SIRT1 inhibitors (amurensin G and EX527) effectively suppressed the resistance to Hsp90 inhibitors (17-AAG and AUY922) in several MDR variants of human lymphoblastic leukemia and human breast cancer cell lines. SIRT1 inhibition down-regulated the expression of heat shock factor 1 (HSF1) and subsequently Hsps and facilitated Hsp90 multichaperone complex disruption via hyperacetylation of Hsp90/Hsp70. These findings were followed by acceleration of ubiquitin ligase CHIP-mediated mutant p53 (mut p53) degradation and subsequent down-regulation of P-gp in 17-AAG-treated MDR cancer cells expressing P-gp and mut p53 after inhibition of SIRT1. Therefore, combined treatment with Hsp90 inhibitor and SIRT1 inhibitor could be a more effective therapeutic approach for Hsp90 inhibitor-resistant MDR cells via down-regulation of HSF1/Hsps, mut p53 and P-gp.

  13. Effect of multidrug resistance modulators on the activity of ivermectin and moxidectin against selected strains of Haemonchus contortus infective larvae

    Directory of Open Access Journals (Sweden)

    Molento Marcelo B.

    2001-01-01

    Full Text Available Nematode parasites have shown resistance to the anthelmintics, ivermectin and moxidectin, and there is evidence that the over-expression of parasite P-glycoprotein (P-gp may account, at least in part, for resistance to ivermectin. The objective of this study was to evaluate whether the multidrug resistance (MDR modulators, verapamil, CL 347.099 (an analog of verapamil and cyclosporin A, would enhance the efficacy of ivermectin and moxidectin against selected strains of Haemonchus contortus using an in vitro larval migration assay. The modulators had no effects on the number of migrating larvae when used alone. Ivermectin and moxidectin showed a significant (P<0.05 increase in its efficacy by 52.8 and 58.5% respectively, when used in association with verapamil against a moxidectin-selected strain. CL 347,099 also increased significantly (P<0.05 the ivermectin and moxidectin efficacy by 24.2 and 40.0% respectively, against an ivermectin-selected strain and by 40.0 and 75.6% respectively, against an moxidectin-selected strain. At the concentrations tested cyclosporin A showed a variable effect on increasing the efficacy of the anthelmintics against the susceptible and resistant strains.

  14. Increased action of triclabendazole (TCBZ) in vitro against a TCBZ-resistant isolate of Fasciola hepatica following its co-incubation with the P-glycoprotein inhibitor, R(+)-verapamil.

    Science.gov (United States)

    Savage, J; Meaney, M; Brennan, G P; Hoey, E; Trudgett, A; Fairweather, I

    2013-11-01

    A study has been carried out to investigate whether the action of triclabendazole (TCBZ) against Fasciola hepatica is altered by inhibition of P-glycoprotein (Pgp)-linked drug efflux pumps. The Sligo TCBZ-resistant fluke isolate was used for these experiments and the Pgp inhibitor selected was R(+)-verapamil [R(+)-VPL]. In the first experiment, flukes were initially incubated for 2h in R(+)-VPL (1×10(-4) M), then incubated in R(+)-VPL + triclabendazole sulphoxide (TCBZ.SO) (50μg/ml) until flukes ceased movement (at 9h post-treatment). In a second experiment, flukes were incubated in TCBZ.SO alone and removed from the incubation medium following cessation of motility (after 15h). In the third experiment, flukes were incubated for 24h in R(+)-VPL on its own. Changes to the tegumental system and gut following drug treatment and following Pgp inhibition were assessed by means of light microscope histology and transmission electron microscopy. Incubation of the Sligo isolate in either R(+)-VPL or TCBZ.SO on their own had a limited impact on the tegumental syncytium and tegumental cells; the changes were consistent with a stress response by the fluke to drug action. Greater disruption was observed when the drugs were combined, in terms of the vacuolation and sloughing of the syncytium, spine disruption and the cessation of secretory activity in, and degradation of, the tegumental cells. In the gut, treatment with R(+)-VPL on its own did not lead to any cellular changes. Some limited changes to the mitochondria and the granular endoplasmic reticulum were observed after incubation in TCBZ.SO alone, together with reduced secretory activity and evidence of autophagy. However, these changes were far more pronounced in combination-treated flukes. The results of this study support the concept of altered drug efflux in TCBZ-resistant flukes and indicate that drug transporters may play a role in the development of drug resistance.

  15. Providing a molecular mechanism for P-glycoprotein; why would I bother?

    Science.gov (United States)

    Callaghan, Richard

    2015-10-01

    It is almost 40 years since the drug efflux pump P-glycoprotein (permeability glycoprotein or P-gp) was shown to confer multi-drug resistance in cancer cells. This protein has been one of the most extensively investigated transport proteins due to its intriguing mechanism and its affect in oncology. P-gp is known to interact with over 300 compounds and the ability to achieve this has not yet been revealed. Following the binding of substrate and nucleotide, a complex series of conformational changes in the membrane and cytosolic domains translocates substrate across the membrane. Despite over 30 years of biochemical investigation, the availability of structural data and a plethora of chemical tools to modulate its function, the molecular mechanism remains a mystery. In addition, overcoming its activity in resistant cancer cells has not been achieved in the clinic, thereby garnering some degree of pessimism in the field. This review highlights the progress that has been achieved in understanding this complex protein and the value of undertaking molecular studies.

  16. Evading P-glycoprotein mediated-efflux chemoresistance using Solid Lipid Nanoparticles.

    Science.gov (United States)

    Cavaco, Marco C; Pereira, Carolina; Kreutzer, Bruna; Gouveia, Luis F; Silva-Lima, Beatriz; Brito, Alexandra M; Videira, Mafalda

    2017-01-01

    Multidrug resistance (MDR), whereby cancer cells become resistant to the cytotoxic effects of various structurally and mechanistically unrelated chemotherapeutic agents, is a major problem in the clinical treatment of cancer. P-glycoprotein (P-gp) is a transmembrane protein responsible for drug efflux, which decreases drug intracellular bioavailability, consequently decreasing their efficacy against cancer. Solid Lipid Nanoparticles (SLNs) have not only the ability to protect the entrapped drug against proteolytic degradation, but also allow a selective intracellular targeting. Hypothetically, the entrapped drug enter the target cells by different uptake mechanisms, "nanocitose", as compared to the free drug and may evade efflux-transporters, like P-gp. The functional role of P-gp in limiting the permeability of the anticancer drug paclitaxel (Ptx) was assessed in MDA-MB-436 cells. The observed increase in the pharmacologic efficacy of drug entrapped in SLN relatively to the free drug indicates that this system is shielding the drug. Therefore, "blinding" the nanoparticle from the efflux transporters. The effect was confirmed by the decrease expression of P-gp with loaded-SLNs and through the impact on cellular MDR1 expression. Besides the ability to prevent MDR events, functionalization of SLN with a specific antibody against membrane receptors (anti-CD44v6) improves the nanoparticle capability to target selectively malignant cells. This results allow to anticipate that poor clinical outcomes related to tumour P-gp overexpression might be overcome in a near future.

  17. pH regulation in sensitive and multidrug resistant Ehrlich ascites tumor cells

    DEFF Research Database (Denmark)

    Litman, Thomas; Pedersen, S F; Kramhøft, B;

    1998-01-01

    Maintenance and regulation of intracellular pH (pHi) was studied in wild-type Ehrlich ascites tumor cells (EHR2) and five progressively daunorubicin-resistant, P-glycoprotein (P-gp)-expressing strains, the maximally resistant of which is EHR2/1.3. Steady-state pHi was similar in cells expressing ...... to aspects of development of drug resistance other than P-gp....

  18. Multidrug-resistant tuberculosis in Europe, 2010-2011

    DEFF Research Database (Denmark)

    Günther, Gunar; van Leth, Frank; Alexandru, Sofia

    2015-01-01

    Drug-resistant Mycobacterium tuberculosis is challenging elimination of tuberculosis (TB). We evaluated risk factors for TB and levels of second-line drug resistance in M. tuberculosis in patients in Europe with multidrug-resistant (MDR) TB. A total of 380 patients with MDR TB and 376 patients...... with non-MDR TB were enrolled at 23 centers in 16 countries in Europe during 2010-2011. A total of 52.4% of MDR TB patients had never been treated for TB, which suggests primary transmission of MDR M. tuberculosis. At initiation of treatment for MDR TB, 59.7% of M. tuberculosis strains tested were...

  19. The secondary resistome of multidrug-resistant Klebsiella pneumoniae

    Science.gov (United States)

    Jana, Bimal; Cain, Amy K.; Doerrler, William T.; Boinett, Christine J.; Fookes, Maria C.; Parkhill, Julian; Guardabassi, Luca

    2017-01-01

    Klebsiella pneumoniae causes severe lung and bloodstream infections that are difficult to treat due to multidrug resistance. We hypothesized that antimicrobial resistance can be reversed by targeting chromosomal non-essential genes that are not responsible for acquired resistance but essential for resistant bacteria under therapeutic concentrations of antimicrobials. Conditional essentiality of individual genes to antimicrobial resistance was evaluated in an epidemic multidrug-resistant clone of K. pneumoniae (ST258). We constructed a high-density transposon mutant library of >430,000 unique Tn5 insertions and measured mutant depletion upon exposure to three clinically relevant antimicrobials (colistin, imipenem or ciprofloxacin) by Transposon Directed Insertion-site Sequencing (TraDIS). Using this high-throughput approach, we defined three sets of chromosomal non-essential genes essential for growth during exposure to colistin (n = 35), imipenem (n = 1) or ciprofloxacin (n = 1) in addition to known resistance determinants, collectively termed the “secondary resistome”. As proof of principle, we demonstrated that inactivation of a non-essential gene not previously found linked to colistin resistance (dedA) restored colistin susceptibility by reducing the minimum inhibitory concentration from 8 to 0.5 μg/ml, 4-fold below the susceptibility breakpoint (S ≤ 2 μg/ml). This finding suggests that the secondary resistome is a potential target for developing antimicrobial “helper” drugs that restore the efficacy of existing antimicrobials. PMID:28198411

  20. Moxidectin has a lower neurotoxic potential but comparable brain penetration in P-glycoprotein-deficient CF-1 mice compared to ivermectin.

    Science.gov (United States)

    Janko, C; Geyer, J

    2013-06-01

    The anti-parasitic drugs ivermectin (IVM) and moxidectin (MOX) normally show limited brain penetration in vertebrates because of effective drug efflux at the blood-brain barrier by P-glycoprotein, encoded by the multi-drug resistance (MDR1) gene. However, dogs with homozygous nt230(del4) mutation in the MDR1 gene do not express a functionally active P-glycoprotein and show increased brain penetration of these drugs, resulting in neurological toxicity to different degrees. Thus, whereas IVM provokes neurological toxicity at 0.1 mg/kg, MOX is tolerated at this dosage. To investigate whether this difference is attributable to lower brain penetration of MOX in the absence of P-glycoprotein or to their neurotoxic potential, we applied IVM and MOX to P-glycoprotein-deficient CF-1 mice and comparatively analysed the absolute drug concentrations in the brain. Furthermore, we quantified drug-induced neurotoxicity by measuring the walking performance of the mice on a rotarod setup. We found that at a dosage of 0.2 mg/kg, representing 0.23 μmol/kg IVM and 0.31 μmol/kg MOX, the absolute drug concentrations in the brain were comparable with 100.8 pmol/g and 140.2 pmol/g, respectively. However, MOX induced the same degree of neurotoxicosis at the higher dosage of 1.09 μmol/kg (0.7 mg/kg) compared with IVM at 0.40 μmol/kg (0.35 mg/kg), demonstrating the 2.7-fold lower neurotoxic potential of MOX compared to IVM. This could be explained by a lower binding affinity or lower intrinsic activity of MOX at the relevant central nervous system receptors compared with IVM.

  1. Knockdown of HOXA10 reverses the multidrug resistance of human chronic mylogenous leukemia K562/ADM cells by downregulating P-gp and MRP-1.

    Science.gov (United States)

    Yi, Ying-Jie; Jia, Xiu-Hong; Wang, Jian-Yong; Li, You-Jie; Wang, Hong; Xie, Shu-Yang

    2016-05-01

    Multidrug resistance (MDR) of leukemia cells is a major obstacle in chemotherapeutic treatment. The high expression and constitutive activation of P-glycoprotein (P-gp) and multidrug resistance protein-1 (MRP-1) have been reported to play a vital role in enhancing cell resistance to anticancer drugs in many tumors. The present study aimed to investigate the reversal of MDR by silencing homeobox A10 (HOXA10) in adriamycin (ADR)-resistant human chronic myelogenous leukemia (CML) K562/ADM cells by modulating the expression of P-gp and MRP-1. K562/ADM cells were stably transfected with HOXA10-targeted short hairpin RNA (shRNA). The results of reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot analysis showed that the mRNA and protein expression of HOXA10 was markedly suppressed following transfection with a shRNA-containing vector. The sensitivity of the K562/ADM cells to ADR was enhanced by the silencing of HOXA10, due to the increased intracellular accumulation of ADR. The accumulation of ADR induced by the silencing of HOXA10 may be due to the downregulation of P-gp and MRP-1. Western blot analysis revealed that downregulating HOXA10 inhibited the protein expression of P-gp and MRP-1. Taken together, these results suggest that knockdown of HOXA10 combats resistance and that HOXA10 is a potential target for resistant human CML.

  2. Heterocyclic cyclohexanone monocarbonyl analogs of curcumin can inhibit the activity of ATP-binding cassette transporters in cancer multidrug resistance.

    Science.gov (United States)

    Revalde, Jezrael L; Li, Yan; Hawkins, Bill C; Rosengren, Rhonda J; Paxton, James W

    2015-02-01

    Curcumin (CUR) is a phytochemical that inhibits the xenobiotic ABC efflux transporters implicated in cancer multidrug resistance (MDR), such as P-glycoprotein (P-gp), breast cancer resistance protein (BCRP) and multidrug resistance-associated proteins 1 and 5 (MRP1 and MRP5). The use of CUR in the clinic however, is complicated by its instability and poor pharmacokinetic profile. Monocarbonyl analogs of CUR (MACs) are compounds without CUR's unstable β-diketone moiety and were reported to have improved stability and in vivo disposition. Whether the MACs can be used as MDR reversal agents is less clear, as the absence of a β-diketone may negatively impact transporter inhibition. In this study, we investigated 23 heterocyclic cyclohexanone MACs for inhibitory effects against P-gp, BCRP, MRP1 and MRP5. Using flow cytometry and resistance reversal assays, we found that many of these compounds inhibited the transport activity of the ABC transporters investigated, often with much greater potency than CUR. Overall the analogs were most effective at inhibiting BCRP and we identified three compounds, A12 (2,6-bis((E)-2,5-dimethoxy-benzylidene)cyclohexanone), A13 (2,6-bis((E)-4-hydroxyl-3-methoxybenzylidene)-cyclohexanone) and B11 (3,5-bis((E)-2-fluoro-4,5-dimethoxybenzylidene)-1-methylpiperidin-4-one), as the most promising BCRP inhibitors. These compounds inhibited BCRP activity in a non-cell line, non-substrate-specific manner. Their inhibition occurred by direct transporter interaction rather than modulating protein or cell surface expression. From these results, we concluded that MACs, such as the heterocyclic cyclohexanone analogs in this study, also have potential as MDR reversal agents and may be superior alternatives to the unstable parent compound, CUR.

  3. Reversal of multidrug resistance phenotype in human breast cancer cells using doxorubicin-liposome-microbubble complexes assisted by ultrasound.

    Science.gov (United States)

    Deng, Zhiting; Yan, Fei; Jin, Qiaofeng; Li, Fei; Wu, Junru; Liu, Xin; Zheng, Hairong

    2014-01-28

    The circumvention of multidrug resistance (MDR) plays a critically important role in the success of chemotherapy. The aim of this work is to investigate the effectiveness and possible mechanisms of the reversal of MDR phenotype in human breast cancer cells by using doxorubicin-liposome-microbubble complexes (DLMC) assisted by ultrasound (US). DLMC is fabricated through conjugating doxorubicin (DOX)-liposome (DL) to the surface of microbubbles (MBs) via the biotin-avidin linkage. The resulting drug-loaded complexes are then characterized and incubated with MCF-7/ADR human breast cancer cells and followed by US exposure. Our results show the more rapid cellular uptake, evident enhancement of nuclear accumulation and less drug efflux in the resistant cells treated by DLMC+US than those treated by DL, DL+verapamil under the same US treatment or DLMC without US. The enhanced drug delivery and cellular uptake also associated with the increase of cytotoxicity against MCF-7/ADR cells, lower MCF-7/ADR cell viability and higher apoptotic cells. Mechanism investigations further disclose a significant increase of reactive oxygen species (ROS) level, enhanced DNA damage and obvious reduction of P-glycoprotein expression in the resistant cells treated with DLMC+US compared with the control cases of cells treated by DLMC, DL+US or DL+verapamil+US. In conclusion, our study demonstrates that DLMC in combination with US may provide an effective delivery of drug to sensitize cells to circumvent MDR and to enhance the therapeutic index of the chemotherapy.

  4. Multidrug-Resistant Tuberculosis: Treatment and Outcomes of 93 Patients

    Directory of Open Access Journals (Sweden)

    Sarah K Brode

    2015-01-01

    Full Text Available BACKGROUND: Tuberculosis (TB remains a leading cause of death worldwide and the emergence of multidrug-resistant TB (MDR TB poses a threat to its control. There is scanty evidence regarding optimal management of MDR TB. The majority of Canadian cases of MDR TB are diagnosed in Ontario; most are managed by the Tuberculosis Service at West Park Healthcare Centre in Toronto. The authors reviewed 93 cases of MDR TB admitted from January 1, 2000 to December 31, 2011.

  5. Daunorubicin and gambogic acid coloaded cysteamine-CdTe quantum dots minimizing the multidrug resistance of lymphoma in vitro and in vivo

    Science.gov (United States)

    Zhou, Yi; Wang, Ruju; Chen, Bing; Sun, Dan; Hu, Yong; Xu, Peipei

    2016-01-01

    To minimize the side effects and the multidrug resistance (MDR) arising from daunorubicin (DNR) treatment of malignant lymphoma, a chemotherapy formulation of cysteamine-modified cadmium tellurium (Cys-CdTe) quantum dots coloaded with DNR and gambogic acid (GA) nanoparticles (DNR-GA-Cys-CdTe NPs) was developed. The physical property, drug-loading efficiency and drug release behavior of these DNR-GA-Cys-CdTe NPs were evaluated, and their cytotoxicity was explored by 3-[4,5-dimethylthiazol-2-y1]-2,5-diphenyltetrazolium bromide assay. These DNR-GA-Cys-CdTe NPs possessed a pH-responsive behavior, and displayed a dose-dependent antiproliferative activity on multidrug-resistant lymphoma Raji/DNR cells. The accumulation of DNR inside the cells, revealed by flow cytometry assay, and the down-regulated expression of P-glycoprotein inside the Raji/DNR cells measured by Western blotting assay indicated that these DNR-GA-Cys-CdTe NPs could minimize the MDR of Raji/DNR cells. This multidrug delivery system would be a promising strategy for minimizing MDR against the lymphoma.

  6. Functional evidence of multidrug resistance transporters (MDR in rodent olfactory epithelium.

    Directory of Open Access Journals (Sweden)

    Adrien Molinas

    Full Text Available BACKGROUND: P-glycoprotein (Pgp and multidrug resistance-associated protein (MRP1 are membrane transporter proteins which function as efflux pumps at cell membranes and are considered to exert a protective function against the entry of xenobiotics. While evidence for Pgp and MRP transporter activity is reported for olfactory tissue, their possible interaction and participation in the olfactory response has not been investigated. PRINCIPAL FINDINGS: Functional activity of putative MDR transporters was assessed by means of the fluorometric calcein acetoxymethyl ester (calcein-AM accumulation assay on acute rat and mouse olfactory tissue slices. Calcein-AM uptake was measured as fluorescence intensity changes in the presence of Pgp or MRP specific inhibitors. Epifluorescence microscopy measured time course analysis in the olfactory epithelium revealed significant inhibitor-dependent calcein uptake in the presence of each of the selected inhibitors. Furthermore, intracellular calcein accumulation in olfactory receptor neurons was also significantly increased in the presence of either one of the Pgp or MRP inhibitors. The presence of Pgp or MRP1 encoding genes in the olfactory mucosa of rat and mouse was confirmed by RT-PCR with appropriate pairs of species-specific primers. Both transporters were expressed in both newborn and adult olfactory mucosa of both species. To assess a possible involvement of MDR transporters in the olfactory response, we examined the electrophysiological response to odorants in the presence of the selected MDR inhibitors by recording electroolfactograms (EOG. In both animal species, MRPs inhibitors induced a marked reduction of the EOG magnitude, while Pgp inhibitors had only a minor or no measurable effect. CONCLUSIONS: The findings suggest that both Pgp and MRP transporters are functional in the olfactory mucosa and in olfactory receptor neurons. Pgp and MRPs may be cellular constituents of olfactory receptor neurons and

  7. Neuronal and glial expression of the multidrug resistance gene product in an experimental epilepsy model.

    Science.gov (United States)

    Lazarowski, Alberto; Ramos, Alberto Javier; García-Rivello, Hernán; Brusco, Alicia; Girardi, Elena

    2004-02-01

    1. Failure of anticonvulsive drugs to prevent seizures is a common complication of epilepsy treatment known as drug-refractory epilepsy but their causes are not well understood. It is hypothesized that the multidrug resistance P-glycoprotein (Pgp-170), the product of the MDR-1 gene that is normally expressed in several excretory tissues including the blood brain barrier, may be participating in the refractory epilepsy. 2. Using two monoclonal antibodies against Pgp-170, we investigated the expression and cellular distribution of this protein in the rat brain during experimentally induced epilepsy. Repeated seizures were induced in male Wistar rats by daily administration of 3-mercaptopropionic acid (MP) 45 mg/kg i.p. for either 4 days (MP-4) or 7 days (MP-7). Control rats received an equivalent volume of vehicle. One day after the last injection, rats were sacrificed and brains were processed for immunohistochemistry for Pgp-170. As it was previously described, Pgp-170 immunostaining was observed in some brain capillary endothelial cells of animals from control group. 3. Increased Pgp-170 immunoreactivity was detected in MP-treated animals. Besides the Pgp-170 expressed in blood vessels, neuronal, and glial immunostaining was detected in hippocampus, striatum, and cerebral cortex of MP-treated rats. Pgp-170 immunolabeled neurons and glial cells were observed in a nonhomogeneous distribution. MP-4 animals presented a very prominent Pgp-170 immunostaining in the capillary endothelium, surrounding astrocytes and some neighboring neurons while MP-7 group showed increased neuronal labeling. 4. Our results demonstrate a selective increase in Pgp-170 immunoreactivity in the brain capillary endothelial cells, astrocytes, and neurons during repetitive MP-induced seizures. 5. The role for this Pgp-170 overexpression in endothelium and astrocytes as a clearance mechanism in the refractory epilepsy, and the consequences of neuronal Pgp-170 expression remain to be disclosed.

  8. Antiviral Drug- and Multidrug Resistance in Cytomegalovirus Infected SCT Patients

    Directory of Open Access Journals (Sweden)

    Katharina Göhring

    2015-01-01

    Full Text Available In pediatric and adult patients after stem cell transplantation (SCT disseminated infections caused by human cytomegalovirus (HCMV can cause life threatening diseases. For treatment, the three antivirals ganciclovir (GCV, foscarnet (PFA and cidofovir (CDV are approved and most frequently used. Resistance to all of these antiviral drugs may induce a severe problem in this patient cohort. Responsible for resistance phenomena are mutations in the HCMV phosphotransferase-gene (UL97 and the polymerase-gene (UL54. Most frequently mutations in the UL97-gene are associated with resistance to GCV. Resistance against all three drugs is associated to mutations in the UL54-gene. Monitoring of drug resistance by genotyping is mostly done by PCR-based Sanger sequencing. For phenotyping with cell culture the isolation of HCMV is a prerequisite. The development of multidrug resistance with mutation in both genes is rare, but it is often associated with a fatal outcome. The manifestation of multidrug resistance is mostly associated with combined UL97/UL54-mutations. Normally, mutations in the UL97 gene occur initially followed by UL54 mutation after therapy switch. The appearance of UL54-mutation alone without any detection of UL97-mutation is rare. Interestingly, in a number of patients the UL97 mutation could be detected in specific compartments exclusively and not in blood.

  9. Natural History of Multi-Drug Resistant Organisms in a New Military Medical Facility

    Science.gov (United States)

    2013-12-01

    Staphylococcus saprophyticus 14 (3) Enterococcus (faecium and faecalis) 11 (2) The remaining 11 species each comprised less than 2% of total 169 (32...environment plays in the transmission of multidrug-resistant Gram-negative bacteria and methicillin-resistant Staphylococcus aureus (MDRO) is increasingly...Pseudomonas aeruginosa, methicillin- resistant Staphylococcus aureus (MRSA); Klebsiella pneumoniea; and Clostridium difficile. Multidrug- resistance (MDR

  10. On the mechanism of substrate/non-substrate recognition by P-glycoprotein.

    Science.gov (United States)

    Mukhametov, Azat; Raevsky, Oleg A

    2017-01-01

    P-Glycoprotein (P-gp, multi-drug resistance protein, MDR1) plays a gatekeeper role, interfering delivery of multiple pharmaceuticals to the target tissues and cells. We performed Molecular Dynamics (MD) simulations to generate fifty side-chain variants for P-gp (PDB ID: 4Q9H-L) followed by docking of 31 drugs (0.6≤ER≤22.7) to the whole surface except the ATPase domains and the extracellular part. A selection of the most negative energy complex for each ligand followed. All compounds docked to the two areas - the main binding cavity at the top of P-gp (12.5% of compounds with ER2), and the binding sites in the middle of P-gp (87.5% of ER2). Our results show that anti-substrates (ER2) might behave differently in relation to the P-gp. According to our calculations, the anti-substrates almost do not bind the main binding cavity (MBC) of P-gp and rather approach the other binding sites on the protein; the substrates preferably bind the MBC; the intermediate compounds with 1≤ER≤2 bind both MBC and other binding sites almost equally. The modelling results are in line with the known hypothesis that binding the MBC is prerequisite for the pumping the compound off the P-gp.

  11. Haemonchus contortus P-glycoprotein-2: in situ localisation and characterisation of macrocyclic lactone transport.

    Science.gov (United States)

    Godoy, Pablo; Lian, Jing; Beech, Robin N; Prichard, Roger K

    2015-01-01

    Haemonchus contortus is a veterinary nematode that infects small ruminants, causing serious decreases in animal production worldwide. Effective control through anthelmintic treatment has been compromised by the development of resistance to these drugs, including the macrocyclic lactones. The mechanisms of resistance in H. contortus have yet to be established but may involve efflux of the macrocyclic lactones by nematode ATP-binding-cassette transporters such as P-glycoproteins. Here we report the expression and functional activity of H. contortus P-glycoprotein 2 expressed in mammalian cells and characterise its interaction with the macrocyclic lactones, ivermectin, abamectin and moxidectin. The ability of H. contortus P-glycoprotein 2 to transport different fluorophore substrates was markedly inhibited by ivermectin and abamectin in a dose-dependent and saturable way. The profile of transport inhibition by moxidectin was markedly different. H. contortus P-glycoprotein 2 was expressed in the pharynx, the first portion of the worm's intestine and perhaps in adjacent nervous tissue, suggesting a role for this gene in regulating the uptake of avermectins and in protecting nematode tissues from the effects of macrocyclic lactone anthelmintic drugs. H. contortus P-glycoprotein 2 may thus contribute to resistance to these drugs in H. contortus.

  12. Reversal of Multidrug Resistance in Breast Cancer

    Science.gov (United States)

    1994-08-23

    cellular resistance to multiple therapeutic agents such as anthracyclines, vinca alkaloids , epipodophyllotoxins, taxol, and actinomycin-D. MDR1 gene...Sci USA 84:3004.1987. Zacher, V., Thomas, R.A., and Goustin, A.S. Absolute quantification of target DNA: a simple competitive PCR for efficient...target appears to be the microtubular apparatus, but unlike vinca alkaloids or epipodophyllotoxin, Paclitaxel actually promotes microtubular assemblyin

  13. Role of P-glycoprotein in refractoriness of seizures to antiepileptic drugs in Lennox-Gastaut syndrome.

    Science.gov (United States)

    Kumar, Achal; Tripathi, Deepak; Paliwal, Vimal Kumar; Neyaz, Zafar; Agarwal, Vikas

    2015-02-01

    Mechanism of seizure refractoriness to antiepileptic drugs in children with Lennox-Gastaut syndrome is not known. Efflux of antiepileptic drugs due to increased expression/function of P-glycoprotein, a multidrug efflux transporter protein on the cell surface is a proposed mechanism. The authors studied the expression/function of P-glycoprotein on peripheral blood mononuclear cells of 29 children with Lennox-Gastaut syndrome, 23 children with other epilepsies, and 19 healthy children. The authors found a higher P-glycoprotein expression/function in Lennox-Gastaut syndrome, a higher percent positive cells as compared to children with other epilepsy (P P = 0.012), higher P-glycoprotein expression as compared to healthy controls (P = 0.003), a higher total P-glycoprotein expression (relative florescence intensity × percent positive cells) as compared to children with other epilepsies (P P P-glycoprotein function as compared to children with other epilepsies (P = 0.001) and healthy controls (P = 0.002). These findings may explain seizure refractoriness to anti-epileptic drugs in Lennox-Gastaut syndome.

  14. Reversal of multidrug resistance in drug-resistant human gastric cancer cell line SGC7901/VCR by antiprogestin drug mifepristone

    Institute of Scientific and Technical Information of China (English)

    Da-Qiang Li; Zhi-Biao Wang; Jin Bai; Jie Zhao; Yuan Wang; Kai Hu; Yong-Hong Du

    2004-01-01

    AIM: To explore the reversal effect of mifepristone on multidrug resistance (MDR) in drug-resistant human gastric cancer cell line SGC7901/VCR and its mechanisms.METHODS: Expression of multidrug resistance-associated protein(MRP) was detected using reverse transcriptionpolymerase chain reaction(RT-PCR). Flow cytometry was used to assay the expression of P-glycoprotein(P-gp), Bcl-2,Bax, and the mean fluorescent intensity of intracellular rhodamine 123 in the cells. Meanwhile, the protein levels of Bcl-2 and Bax were also detected by Western blotting analysis. The sensitivity of cells to the anticancer agent,vincrimycin(VCR), and the intracellular [3H]VCR accumulation were determined by tetrazolium blue (MTT) assay and a liquid scintillation counter, respectively.RESULTS: Expression of MRP and P-gp in SGC7901/VCR cells was 6.04-and 8.37-fold higher as compared with its parental SGC7901 cells, respectively. After treatment with 1, 5, 10, and 20 μmol/L mifepristone, SGC7901/VCR cells showed a 1.34-, 2.29-, 3.11-, and 3.71-fold increase in the accumulation of intracellular VCR, a known substrate of MRP,and a 1.03-, 2.04-, 3.08-, and 3.68-fold increase in the retention of rhodamine 123, an indicator of P-gp function, respectively.MTT assay revealed that the resistance of SGC7901/VCR cells to VCR was 11.96-fold higher than that of its parental cells. The chemosensitivity of SGC7901/VCR cells to VCR was enhanced by 1.02-, 7.19-, 12.84-, and 21.17-fold after treatment with mifepristone at above-mentioned dose. After 96 h of incubation with mifepristone 10 μmol/L, a concentration close to plasma concentrations achievable in human, the expression of Bcl-2 protein was decreased to (9.21±0.65)%from (25.32±1.44)%, whereas the expression of Bax protein was increased to (19.69±1.13)% from (1.24±0.78)%(P<0.01). Additionally, the effects of mifepristone on the expression of Bcl-2 and Bax proteins in SGC7901/VCR cells were further demonstrated by Western blotting analysis

  15. Overcoming Multidrug Resistance in Cancer Stem Cells

    Directory of Open Access Journals (Sweden)

    Karobi Moitra

    2015-01-01

    Full Text Available The principle mechanism of protection of stem cells is through the expression of ATP-binding cassette (ABC transporters. These transporters serve as the guardians of the stem cell population in the body. Unfortunately these very same ABC efflux pumps afford protection to cancer stem cells in tumors, shielding them from the adverse effects of chemotherapy. A number of strategies to circumvent the function of these transporters in cancer stem cells are currently under investigation. These strategies include the development of competitive and allosteric modulators, nanoparticle mediated delivery of inhibitors, targeted transcriptional regulation of ABC transporters, miRNA mediated inhibition, and targeting of signaling pathways that modulate ABC transporters. The role of ABC transporters in cancer stem cells will be explored in this paper and strategies aimed at overcoming drug resistance caused by these particular transporters will also be discussed.

  16. The purified and functionally reconstituted multidrug transporter LmrA of Lactococcus lactis mediates the transbilayer movement of specific fluorescent phospholipids

    NARCIS (Netherlands)

    Margolles, A; Putman, M; van Veen, HW; Konings, WN

    1999-01-01

    Lactococcus lactis possesses an ATP-binding cassette transporter, LmrA, which is a homolog of the mammalian multidrug resistance (MDR) P-glycoprotein, and is able to transport a broad range of structurally unrelated amphiphilic drugs. A histidine tag was introduced at the N-terminus of LmrA to facil

  17. Photoexcited quantum dots for killing multidrug-resistant bacteria

    Science.gov (United States)

    Courtney, Colleen M.; Goodman, Samuel M.; McDaniel, Jessica A.; Madinger, Nancy E.; Chatterjee, Anushree; Nagpal, Prashant

    2016-05-01

    Multidrug-resistant bacterial infections are an ever-growing threat because of the shrinking arsenal of efficacious antibiotics. Metal nanoparticles can induce cell death, yet the toxicity effect is typically nonspecific. Here, we show that photoexcited quantum dots (QDs) can kill a wide range of multidrug-resistant bacterial clinical isolates, including methicillin-resistant Staphylococcus aureus, carbapenem-resistant Escherichia coli, and extended-spectrum β-lactamase-producing Klebsiella pneumoniae and Salmonella typhimurium. The killing effect is independent of material and controlled by the redox potentials of the photogenerated charge carriers, which selectively alter the cellular redox state. We also show that the QDs can be tailored to kill 92% of bacterial cells in a monoculture, and in a co-culture of E. coli and HEK 293T cells, while leaving the mammalian cells intact, or to increase bacterial proliferation. Photoexcited QDs could be used in the study of the effect of redox states on living systems, and lead to clinical phototherapy for the treatment of infections.

  18. Targeted multidrug-resistance reversal in tumor based on PEG-PLL-PLGA polymer nano drug delivery system

    Directory of Open Access Journals (Sweden)

    Guo L

    2015-07-01

    Full Text Available Liting Guo,1 Haijun Zhang,1 Fei Wang,1 Ping Liu,1 Yonglu Wang,1,2 Guohua Xia,1 Ran Liu,1 Xueming Li,2 Haixiang Yin,2 Hulin Jiang,3 Baoan Chen11Department of Hematology and Oncology (Key Department of Jiangsu Medicine, The Affiliated Zhongda Hospital, Medical School of Southeast University, 2School of Pharmacy, Nanjing University of Technology, 3Department of Pharmaceutics, School of Pharmacy, China Pharmaceutical University, Nanjing, People’s Republic of ChinaAbstract: The study investigated the reversal of multidrug resistance (MDR and the biodistribution of nanoparticles (NPs that target leukemia cells in a nude mice model via a surface-bound transferrin (Tf. The cytotoxic cargo of daunorubicin (DNR and tetrandrine (Tet was protected in the NPs by an outer coat composed of polyethylene glycol (PEG-poly-l-lysine (PLL-poly(lactic-co-glycolic acid (PLGA NPs. Injection of DNR-Tet-Tf-PEG-PLL-PLGA NPs into nude mice bearing MDR leukemia cell K562/A02 xenografts was shown to inhibit tumor growth, and contemporaneous immunohistochemical analysis of tumor tissue showed the targeted NPs induced apoptosis in tumor cells. Targeted tumor cells exhibited a marked increase in Tf receptor expression, with noticeable decreases in P-glycoprotein, MDR protein, and nuclear factor κB, as assessed by quantitative real-time polymerase chain reaction and Western blot analysis. Moreover, the concentration of DNR was shown to increase in plasma, tumor tissue, and major organs. Flow cytometry analysis with a near-infrared fluorescent (NIRF dye, NIR797, was used to study the effectiveness of Tf as a targeting group for leukemia cells, a finding that was supported by NIRF imaging in tumor-bearing nude mice. In summary, our studies show that DNR-Tet-Tf-PEG-PLL-PLGA NPs provide a specific and effective means to target cytotoxic drugs to MDR tumor cells.Keywords: PEG-PLL-PLGA nanoparticles, transferrin, tetrandrine, multidrug resistance

  19. MULTIDRUG RESISTANT BACTERIA IN A TERTIARY CARE HOS PITAL.

    Directory of Open Access Journals (Sweden)

    Sujata

    2012-12-01

    Full Text Available ABSTRACT: BACKGROUND: Antibiotic resistance is a global problem in the hos pitals as well as in the community. Selection pressure exerted by over use of antimicrobial agents is the commonest predisposing factor of development of resist ance. Problems faced are especially with Methicillin Resistant Staphylococcus aureus (MR SA, Vancomycin Resistant Enterococci (VRE and Multidrug resistant Gram-negative bacilli (MDR-GNB. AIMS: A study was undertaken to find out the prevalence of all bacteri a isolated in this hospital from different specimens, which are resistant to first line antibio tics and their antimicrobial susceptibility pattern with higher antibiotics during a six-month pe riod. MATERIAL AND METHODS: All isolates from different specimens were processed by s tandard techniques and identified by standard biochemical tests. Antibiotic susceptibilit y was performed on Mueller Hinton Agar (MHA by Kirby-Bauer Disc Diffusion Method (KBDDM, according to CLSI guidelines. Those resistant to first line antibiotics were further te sted for higher antibiotics. For Extended Spectrum β -lactamse (ESBL detection, double disc synergy met hod was carried out for all Gram-negative bacilli. RESULTS: Out of 2987 bacteria grown, 904 (30.3% were multi drug resistant bacteria. Resistance to first line antib iotics was 83.4% and resistance to all higher antibiotics tested was 16.6%. Sixty percent of Staph ylococcus aureus was MRSA and all were sensitive to vancomycin. Prevalence of VRE was 5.3 %. Carbapenem resistant Pseudomonas aeruginosa and Acinetobacter species were 19.1% and 9.8% respectively and 10.1% of Klebsiella species was carbapenem resistant. CONCLUSIONS: This study highlights the extensive problem of antibiotic resistance encounter ed in this hospital. Thus, prudent and appropriate uses of antibiotics are required to reduce the emergence of resistance. Each hospital should also have its own antibiotic policy based on the susceptibility pattern of

  20. Molecular cloning of cDNAs which are highly overexpressed in mitoxantrone-resistant cells

    DEFF Research Database (Denmark)

    Miyake, K; Mickley, L; Litman, Thomas;

    1999-01-01

    Reports of multiple distinct mitoxantrone-resistant sublines without overexpression of P-glycoprotein or the multidrug-resistance associated protein have raised the possibility of the existence of another major transporter conferring drug resistance. In the present study, a cDNA library from mito...

  1. [Multidrug-resistant tuberculosis: current epidemiology, therapeutic regimens, new drugs].

    Science.gov (United States)

    Gómez-Ayerbe, C; Vivancos, M J; Moreno, S

    2016-09-01

    Multidrug and extensively resistant tuberculosis are especially severe forms of the disease for which no efficacious therapy exists in many cases. All the countries in the world have registered cases, although most of them are diagnosed in resource-limited countries from Asia, Africa and South America. For adequate treatment, first- and second-line antituberculosis drugs have to be judiciously used, but the development of new drugs with full activity, good tolerability and little toxicity is urgently needed. There are some drugs in development, some of which are already available through expanded-access programs.

  2. Overcoming multidrug resistance(MDR) in cancer by nanotechnology

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The emerging nanotechnology-based drug delivery holds tremendous potential to deliver chemotherapeutic drugs for treatment of multidrug resistance(MDR) cancer.This drug delivery system could improve the pharmacokinetic behavior of antitumor drugs,deliver chemotherapeutic drugs to target sites,control release of drugs,and reduce the systemic toxicity of drugs in MDR cancer.This review addresses the use of nanotechnology to overcome MDR classified on the bases of the fundamental mechanisms of MDR and various approaches to deliver drugs for treatment of MDR cancer.

  3. Human Multidrug Resistance 1 gene polymorphisms and Idiopathic Pulmonary Fibrosis

    Science.gov (United States)

    Martinelli, Marcella; Scapoli, Luca; Pacilli, Angela Maria Grazia; Carbonara, Paolo; Girardi, Ambra; Mattei, Gabriella; Rodia, Maria Teresa; Solmi, Rossella

    2015-01-01

    Background: For the first time we tested an association between the human multidrug resistance gene 1 (MDR1) polymorphisms (SNPs) and idiopathic pulmonary fibrosis (IPF). Several MDR1 polymorphisms are associated with pathologies in which they modify the drug susceptibility and pharmacokinetics. Materials and Methods: We genotyped three MDR1 polymorphisms of 48 IPF patients and 100 control subjects with Italian origins. Results: No evidence of association was detected. Conclusion: There are 50 known MDR1 SNPs, and their role is explored in terms of the effectiveness of drug therapy. We consider our small-scale preliminary study as a starting point for further research. PMID:25767528

  4. Transport of diclofenac by breast cancer resistance protein (ABCG2) and stimulation of multidrug resistance protein 2 (ABCC2)-mediated drug transport by diclofenac and benzbromarone.

    Science.gov (United States)

    Lagas, Jurjen S; van der Kruijssen, Cornelia M M; van de Wetering, Koen; Beijnen, Jos H; Schinkel, Alfred H

    2009-01-01

    Diclofenac is an important analgesic and anti-inflammatory drug, widely used for treatment of postoperative pain, rheumatoid arthritis, and chronic pain associated with cancer. Consequently, diclofenac is often used in combination regimens and undesirable drug-drug interactions may occur. Because many drug-drug interactions may occur at the level of drug transporting proteins, we studied interactions of diclofenac with apical ATP-binding cassette (ABC) multidrug efflux transporters. Using Madin-Darby canine kidney (MDCK)-II cells transfected with human P-glycoprotein (P-gp; MDR1/ABCB1), multidrug resistance protein 2 (MRP2/ABCC2), and breast cancer resistance protein (BCRP/ABCG2) and murine Bcrp1, we found that diclofenac was efficiently transported by murine Bcrp1 and moderately by human BCRP but not by P-gp or MRP2. Furthermore, in Sf9-BCRP membrane vesicles diclofenac inhibited transport of methotrexate in a concentration-dependent manner. We next used MDCK-II-MRP2 cells to study interactions of diclofenac with MRP2-mediated drug transport. Diclofenac stimulated paclitaxel, docetaxel, and saquinavir transport at only 50 microM. We further found that the uricosuric drug benzbromarone stimulated MRP2 at an even lower concentration, having maximal stimulatory activity at only 2 microM. Diclofenac and benzbromarone stimulated MRP2-mediated transport of amphipathic lipophilic drugs at 10- and 250-fold lower concentrations, respectively, than reported for other MRP2 stimulators. Because these concentrations are readily achieved in patients, adverse drug-drug interactions may occur, for example, during cancer therapy, in which drug concentrations are often critical and stimulation of elimination via MRP2 may result in suboptimal chemotherapeutic drug concentrations. Moreover, stimulation of MRP2 activity in tumors may lead to increased efflux of chemotherapeutic drugs and thereby drug resistance.

  5. Effect of methylglyoxal on multidrug-resistant Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Katsuhiko eHayashi

    2014-04-01

    Full Text Available Honey has a complex chemistry, and its broad-spectrum antimicrobial activity varies with floral source, climate, and harvesting conditions. Methylglyoxal was identified as the dominant antibacterial component of manuka honey. Although it has been known that methylglyoxal has antibacterial activity against gram-positive bacteria, including methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus, there is not much information describing its activity against gram-negative bacteria. In this study, we report the effect of methylglyoxal against multidrug-resistant Pseudomonas aeruginosa (MDRP using 53 clinically isolated strains. We also assessed the effect of deleting the five multidrug efflux systems in P. aeruginosa, as well as the efflux systems in Escherichia coli and Salmonella enterica serovar Typhimurium, on MICs of methylglyoxal. Our results indicate that methylglyoxal inhibits the growth of MDRP at concentrations of 128–512 µg/ml (1.7–7.1 mM and is not recognized by drug efflux systems.

  6. Second-line drug resistance in multidrug-resistant tuberculosis cases of various origins in the Netherlands.

    NARCIS (Netherlands)

    Ingen, J. van; Boeree, M.J.; Wright, A.; Laan, T.; Dekhuijzen, P.N.R.; Soolingen, D van

    2008-01-01

    SETTING: The Netherlands. OBJECTIVE: To investigate the frequency of resistance to second-line drugs among multidrug-resistant tuberculosis (MDR-TB) cases and its correlation with patients' geographic origin. DESIGN: Retrospective laboratory database study of multidrug-resistant Mycobacterium tuberc

  7. Novel understanding of ABC transporters ABCB1/MDR/P-glycoprotein, ABCC2/MRP2, and ABCG2/BCRP in colorectal pathophysiology

    DEFF Research Database (Denmark)

    Andersen, Vibeke; Svenningsen, Katrine; Almind Knudsen, Lina;

    2015-01-01

    transporter proteins, inflammatory bowel disease, ulcerative, colitis, Crohns disease, colorectal cancer, colitis, intestinal inflammation, intestinal carcinogenesis, ABCB1/P-glycoprotein (P-gp/CD243/MDR1), ABCC2/multidrug resistance protein 2 (MRP2) and ABCG2/breast cancer resistance protein (BCRP), Abcb1....../Mdr1a, abcc2/Mrp2, abcg2/Bcrp, knock-out mice, tight junction, membrane lipid function. RESULTS: Recently, human studies reported that changes in the levels of ABC transporters were early events in the adenoma-carcinoma sequence leading to CRC. A link between ABCB1, high fat diet and gut microbes...... translocation from one side to the other of the cell membrane lipid bilayer by ABC transporters affecting inflammatory response and/or function of tight junctions, phagocytosis and vesicle trafficking. Also, diet and microbes give rise to molecules which are potential substrates for the ABC transporters...

  8. The role of multidrug resistance-associated protein in the blood-brain barrier and opioid analgesia.

    Science.gov (United States)

    Su, Wendy; Pasternak, Gavril W

    2013-09-01

    The blood-brain barrier protects the brain from circulating compounds and drugs. The ATP-binding cassette (ABC) transporter P-glycoprotein (Pgp) is involved with the barrier, both preventing the influx of agent from the blood into the brain and facilitating the efflux of compounds from the brain into the blood, raising the possibility of a similar role for other transporters. Multidrug resistance-associated protein (MRP), a 190 kDa protein, similar to Pgp is also ABC transporter that has been implicated in the blood-brain barrier. The current study explores its role in opioid action. Immunohistochemically, it is localized in the choroid plexus in rats and can be selectively downregulated by antisense treatment at both the level of mRNA, as shown by RT-PCR, and protein, as demonstrated immunohistochemically. Behaviorally, downregulation of MRP significantly enhances the analgesic potency of systemic morphine in MRP knockout mice and in antisense-treated rats by lowering the blood-brain barrier. Following intracerebroventricular administration, a number of compounds, including some opioids, are rapidly secreted from the brain into the blood where they contribute to the overall analgesic effects by activating peripheral systems. MRP plays a role in this efflux. Downregulating MRP expression leads to a corresponding decrease in the transport and a diminished analgesic response from opioids administered intracerebroventricularly. Thus, the transporter protein MRP plays a role in maintaining the blood-brain barrier and modulates the activity of opioids.

  9. Multidrug-resistant pathogens in the food supply.

    Science.gov (United States)

    Doyle, Marjorie E

    2015-04-01

    Antimicrobial resistance, including multidrug resistance (MDR), is an increasing problem globally. MDR bacteria are frequently detected in humans and animals from both more- and less-developed countries and pose a serious concern for human health. Infections caused by MDR microbes may increase morbidity and mortality and require use of expensive drugs and prolonged hospitalization. Humans may be exposed to MDR pathogens through exposure to environments at health-care facilities and farms, livestock and companion animals, human food, and exposure to other individuals carrying MDR microbes. The Centers for Disease Control and Prevention classifies drug-resistant foodborne bacteria, including Campylobacter, Salmonella Typhi, nontyphoidal salmonellae, and Shigella, as serious threats. MDR bacteria have been detected in both meat and fresh produce. Salmonellae carrying genes coding for resistance to multiple antibiotics have caused numerous foodborne MDR outbreaks. While there is some level of resistance to antimicrobials in environmental bacteria, the widespread use of antibiotics in medicine and agriculture has driven the selection of a great variety of microbes with resistance to multiple antimicrobials. MDR bacteria on meat may have originated in veterinary health-care settings or on farms where animals are given antibiotics in feed or to treat infections. Fresh produce may be contaminated by irrigation or wash water containing MDR bacteria. Livestock, fruits, and vegetables may also be contaminated by food handlers, farmers, and animal caretakers who carry MDR bacteria. All potential sources of MDR bacteria should be considered and strategies devised to reduce their presence in foods. Surveillance studies have documented increasing trends in MDR in many pathogens, although there are a few reports of the decline of certain multidrug pathogens. Better coordination of surveillance programs and strategies for controlling use of antimicrobials need to be implemented in

  10. Draft Genome of the Multidrug-Resistant Acinetobacter baumannii Strain A155 Clinical Isolate.

    Science.gov (United States)

    Arivett, Brock A; Fiester, Steven E; Ream, David C; Centrón, Daniela; Ramírez, Maria S; Tolmasky, Marcelo E; Actis, Luis A

    2015-03-26

    Acinetobacter baumannii is a bacterial pathogen with serious implications on human health, due to increasing reports of multidrug-resistant strains isolated from patients. Total DNA from the multidrug-resistant A. baumannii strain A155 clinical isolate was sequenced to greater than 65× coverage, providing high-quality contig assemblies.

  11. The lactococcal secondary multidrug transporter LmrP confers resistance to lincosamides, macrolides, streptogramins and tetracyclines

    NARCIS (Netherlands)

    Putman, M; van Veen, HW; Degener, JE; Konings, WN

    2001-01-01

    The active efflux of toxic compounds by (multi)drug transporters is one of the mechanisms that bacteria have developed to resist cytotoxic drugs. The authors describe the role of the lactococcal secondary multidrug transporter LmrP in the resistance to a broad range of clinically important antibioti

  12. Long-term Administration Induced P-glycoprotein-mediated Drug Resistance at Blood-Brain Barrier%长期用药在血脑屏障上诱导P-糖蛋白介导的耐药性

    Institute of Scientific and Technical Information of China (English)

    何玲; 张陆勇; 刘国卿

    2003-01-01

    目的:考察长期用药在血脑屏障上是否引起耐药性及P-糖蛋白(P-gp)表达增强.方法:原代牛脑微血管内皮细胞(BCEC)加入环孢素A(CsA),长春新碱(VCR),阿霉素(Dox),或粉防己碱(Tet),初始剂量分别为0.0083,0.091,0.34,或0.32 μmol/L,培养至传代剂量翻倍.连续作用21,37,51或69 d后,用罗丹明123(Rh123)检测P-gp功能.将各药物诱导69天的BCEC制膜,用酶联免疫吸附法(ELISA)测定P-gp表达.结果:Dox用药37 d使胞内Rh123浓度降低38%.连续给药51和69 d后,Dox分别使胞内Rh123浓度降低47%和57%,VCR组分别降低36%和40%.而CsA和Tet组一直未见明显变化.维拉帕米(10μmol/L)分别使CsA、Tet、Dox和VCR诱导组BCEC内Rh123的摄取增加92%、85%、143%和186%.Dox和VCR连续用药69 d使P-gp的表达增强45%和32%.结论:长期使用Dox或VCR可在血脑屏障上诱导P-gp介导的耐药性以及P-gp表达增强.%AIM: To study whether long-term administration could induce drug resistance and P-glycoprotein(P-gp) expression at blood-brain barrier(BBB). METHOD: Primary bovine brain capillary endothelial cells(BCECs) were cultured in the presence of cyclosporin A(CsA),vincrinstine(VCR),doxorubicin(Dox),or tetrandrine(Tet) at the original concentration of 0.0083,0.091,0.34,or 0.32 μmol/L,respectively. The drug was maintained until the BCECs approached confluence,at which point the subculture and doubling of drug would be repeated,and the whole process continued through 4-5 cycles. Using rhodamine 123(Rh123) to examine the functional activity of P-gp expressed in drug-treated BCECs after a period of 21,37,51,and 69 d respectively. The plasma membranes of BCECs pretreated with inducing drug for 69 d were isolated and prepared,and the P-gp expression in the plasma membranes was detected by enzyme-linked immunosorbent assay(ELISA). RESULT: No significant change in P-gp function was observed in comparison with the control on d21. Administration of Dox obviously decreased the

  13. How to Measure Export via Bacterial Multidrug Resistance Efflux Pumps

    Directory of Open Access Journals (Sweden)

    Jessica M. A. Blair

    2016-07-01

    Full Text Available Bacterial multidrug resistance (MDR efflux pumps are an important mechanism of antibiotic resistance and are required for many pathogens to cause infection. They are also being harnessed to improve microbial biotechnological processes, including biofuel production. Therefore, scientists of many specialties must be able to accurately measure efflux activity. However, myriad methodologies have been described and the most appropriate method is not always clear. Within the scientific literature, many methods are misused or data arising are misinterpreted. The methods for measuring efflux activity can be split into two groups, (i those that directly measure efflux and (ii those that measure the intracellular accumulation of a substrate, which is then used to infer efflux activity. Here, we review the methods for measuring efflux and explore the most recent advances in this field, including single-cell or cell-free technologies and mass spectrometry, that are being used to provide more detailed information about efflux pump activity.

  14. bba, a synthetic derivative of 23-hydroxybutulinic acid, reverses multidrug resistance by inhibiting the efflux activity of MRP7 (ABCC10.

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    Jun-Jiang Chen

    Full Text Available Natural products are frequently used for adjuvant chemotherapy in cancer treatment. 23-O-(1,4'-bipiperidine-1-carbonyl betulinic acid (BBA is a synthetic derivative of 23-hydroxybutulinic acid (23-HBA, which is a natural pentacyclic triterpene and the major active constituent of the root of Pulsatillachinensis. We previously reported that BBA could reverse P-glycoprotein (P-gp/ABCB1-mediated multidrug resistance (MDR. In the present study, we investigated whether BBA has the potential to reverse multidrug resistance protein 7 (MRP7/ABCC10-mediated MDR. We found that BBA concentration-dependently enhanced the sensitivity of MRP7-transfected HEK293 cells to paclitaxel, docetaxel and vinblastine. Accumulation and efflux experiments demonstrated that BBA increased the intracellular accumulation of [(3H]-paclitaxel by inhibiting the efflux of [(3H]-paclitaxel from HEK293/MRP7 cells. In addition, immunoblotting and immunofluorescence analyses indicated no significant alteration of MRP7 protein expression and localization in plasma membranes after treatment with BBA. These results demonstrate that BBA reverses MRP7-mediated MDR through blocking the drug efflux function of MRP7 without affecting the intracellular ATP levels. Our findings suggest that BBA has the potential to be used in combination with conventional chemotherapeutic agents to augment the response to chemotherapy.

  15. Clinical relevance of P-glycoprotein expression in haematological malignancies

    NARCIS (Netherlands)

    K. Nooter (Kees); P. Sonneveld (Pieter)

    1994-01-01

    textabstractAlthough, generally speaking, haematological malignancies are chemotherapy-responsive tumours and high remission induction rates are obtained, disease-related death is the rule rather than the exception. The appearance of cell populations, resistant to multidrug-based chemotherapy, const

  16. A gene optimization strategy that enhances production of fully functional P-glycoprotein in Pichia pastoris.

    Directory of Open Access Journals (Sweden)

    Jiangping Bai

    Full Text Available BACKGROUND: Structural and biochemical studies of mammalian membrane proteins remain hampered by inefficient production of pure protein. We explored codon optimization based on highly expressed Pichia pastoris genes to enhance co-translational folding and production of P-glycoprotein (Pgp, an ATP-dependent drug efflux pump involved in multidrug resistance of cancers. METHODOLOGY/PRINCIPAL FINDINGS: Codon-optimized "Opti-Pgp" and wild-type Pgp, identical in primary protein sequence, were rigorously analyzed for differences in function or solution structure. Yeast expression levels and yield of purified protein from P. pastoris (∼130 mg per kg cells were about three-fold higher for Opti-Pgp than for wild-type protein. Opti-Pgp conveyed full in vivo drug resistance against multiple anticancer and fungicidal drugs. ATP hydrolysis by purified Opti-Pgp was strongly stimulated ∼15-fold by verapamil and inhibited by cyclosporine A with binding constants of 4.2±2.2 µM and 1.1±0.26 µM, indistinguishable from wild-type Pgp. Maximum turnover number was 2.1±0.28 µmol/min/mg and was enhanced by 1.2-fold over wild-type Pgp, likely due to higher purity of Opti-Pgp preparations. Analysis of purified wild-type and Opti-Pgp by CD, DSC and limited proteolysis suggested similar secondary and ternary structure. Addition of lipid increased the thermal stability from T(m ∼40 °C to 49 °C, and the total unfolding enthalpy. The increase in folded state may account for the increase in drug-stimulated ATPase activity seen in presence of lipids. CONCLUSION: The significantly higher yields of protein in the native folded state, higher purity and improved function establish the value of our gene optimization approach, and provide a basis to improve production of other membrane proteins.

  17. STUDIES ON ANTIBACTERIAL EFFECT OF APAMARGA (ACHYRANTHES ASPERA ON MULTI-DRUG RESISTANT CLINICAL ISOLATES

    Directory of Open Access Journals (Sweden)

    Patil Usha

    2013-04-01

    Full Text Available Recent reports on emergence of multidrug resistant bacteria are cause of concern in medical world. Several ayurvedic drugs have been proved to contain the antimicrobial activity. Literature on effect of ayurvedic drugs on multidrug resistant bacterial pathogens is limited. Present study reports the antimicrobial effect of Achyranthes aspera (Apamarga crude extracts on the clinical isolates of multidrug resistant bacteria. The drug was evaluated by using phytochemical tests. Crude extracts of aqueous, methanol, ethanol and chloroform was prepared. Antibacterial activity against clinically isolated multidrug resistant bacteria belonging to groups of bacillus, citrobacter, E.coli, klebsiella, proteus and salmonella was tested. The drug showed highest efficacy against Bacillus organism while least effectiveness on Proteus spp bacteria. Results of the study conclude that the medicinal plant A. aspera might be useful against multidrug resistance in pathogens of clinical importance.

  18. Antibiotic resistance determinants of a group of multidrug-resistant Acinetobacter baumannii in China.

    Science.gov (United States)

    Xiao-Min, Xu; You-Fen, Fan; Wei-Yun, Feng; Zu-Huang, Mi; Xing-Bei, Weng

    2014-06-01

    A group of Acinetobacter baumannii confers multidrug resistance, but the molecular epidemiology and multidrug resistance mechanisms are poorly understood. Nineteen isolates were identified, and the antimicrobial susceptibility profile was determined using the disc diffusion method. Then, PCR of 78 kinds of resistance-associated genes were performed. A novel variant of blaADC gene: blaADC-67 gene (Genbank accession No. JX169789) was prevalent in all 19 isolates. Moreover, ISAba1 could also provide strong promoter to upregulate the expression of blaADC67 to confer resistance to beta-lactam. This is the first report of emergence of blaADC-67 in A. baumannii worldwide, which might confer resistance to beta-lactam.

  19. Synergistic effect of folate-mediated targeting and verapamil-mediated P-gp inhibition with paclitaxel -polymer micelles to overcome multi-drug resistance.

    Science.gov (United States)

    Wang, Feihu; Zhang, Dianrui; Zhang, Qiang; Chen, Yuxuan; Zheng, Dandan; Hao, Leilei; Duan, Cunxian; Jia, Lejiao; Liu, Guangpu; Liu, Yue

    2011-12-01

    Multidrug resistance (MDR) in tumor cells is a significant obstacle for successful cancer chemotherapy. Overexpression of drug efflux transporters such as P-glycoprotein (P-gp) is a key factor contributing to the development of tumor drug resistance. Verapamil (VRP), a P-gp inhibitor, has been reported to be able to reverse completely the resistance caused by P-gp. For optimal synergy, the drug and inhibitor combination may need to be temporally colocalized in the tumor cells. Herein, we investigated the effectiveness of simultaneous and targeted delivery of anticancer drug, paclitaxel (PTX), along with VRP, using DOMC-FA micelles to overcome tumor drug resistance. The floate-functionalized dual agent loaded micelles resulted in the similar cytotoxicity to PTX-loaded micelles/free VRP combination and co-administration of two single-agent loaded micelles, which was higher than that of PTX-loaded micelles. Enhanced therapeutic efficacy of dual agent micelles could be ascribe to increased accumulation of PTX in drug-resistant tumor cells. We suggest that the synergistic effect of folate receptor-mediated internalization and VRP-mediated overcoming MDR could be beneficial in treatment of MDR solid tumors by targeting delivery of micellar PTX into tumor cells. As a result, the difunctional micelle systems is a very promising approach to overcome tumor drug resistance.

  20. Purification of a Multidrug Resistance Transporter for Crystallization Studies

    Directory of Open Access Journals (Sweden)

    Kamela O. Alegre

    2015-03-01

    Full Text Available Crystallization of integral membrane proteins is a challenging field and much effort has been invested in optimizing the overexpression and purification steps needed to obtain milligram amounts of pure, stable, monodisperse protein sample for crystallography studies. Our current work involves the structural and functional characterization of the Escherichia coli multidrug resistance transporter MdtM, a member of the major facilitator superfamily (MFS. Here we present a protocol for isolation of MdtM to increase yields of recombinant protein to the milligram quantities necessary for pursuit of structural studies using X-ray crystallography. Purification of MdtM was enhanced by introduction of an elongated His-tag, followed by identification and subsequent removal of chaperonin contamination. For crystallization trials of MdtM, detergent screening using size exclusion chromatography determined that decylmaltoside (DM was the shortest-chain detergent that maintained the protein in a stable, monodispersed state. Crystallization trials of MdtM performed using the hanging-drop diffusion method with commercially available crystallization screens yielded 3D protein crystals under several different conditions. We contend that the purification protocol described here may be employed for production of high-quality protein of other multidrug efflux members of the MFS, a ubiquitous, physiologically and clinically important class of membrane transporters.

  1. Protein phosphatase complex PP5/PPP2R3C dephosphorylates P-glycoprotein/ABCB1 and down-regulates the expression and function.

    Science.gov (United States)

    Katayama, Kazuhiro; Yamaguchi, Miho; Noguchi, Kohji; Sugimoto, Yoshikazu

    2014-04-01

    P-glycoprotein (P-gp)/ABCB1 is a key molecule of multidrug resistance in cancer. Protein phosphatase (PP) 2A, regulatory subunit B, gamma (PPP2R3C), which is a regulatory subunit of PP2A and PP5, was identified as a binding candidate to P-gp. Immunoprecipitation-western blotting revealed that PP5 and PPP2R3C were coprecipitated with P-gp, while PP2A was not. PP5/PPP2R3C dephosphorylated protein kinase A/protein kinase C-phosphorylation of P-gp. Knockdown of PP5 and/or PPP2R3C increased P-gp expression and lowered the sensitivity to vincristine and doxorubicin. Consequently, our results indicate that PP5/PPP2R3C negatively regulates P-gp expression and function.

  2. Establishment of a Multidrug Resistance Cell Line A549/cDDP of Human Lung Adenocarcinoma and Expression Analysis of Multidrug Resistance-Associated Genes

    Directory of Open Access Journals (Sweden)

    Yongcheng PAN

    2009-03-01

    Full Text Available Background and objective It has been proven that chemotherapy failure caused by multidrug resistance in lung tumor cells is the main cause for the patient's survival rate. The aim of this study is to establish a multidrug resistance cell line of human lung adenocarcinoma and study the mechanism of multidrug resistance. Methods Human lung adenocarcinoma cell line A549 was induced to multidrug resistance cell line A549/cDDP by intermittentadministration of high dose of cisplatin (cDDP. The multidrug resistance was detected by using MTT assay. The levels of expression of MDR-1 gene-coded P-glycoportein (P-gp, multidrug resistance-associated protein (MRP, and GSH/GST were examined by flow cytometric assay. The levels of expression of MDR and MRP gene were also detected by RTPCR in both A549/cDDP and A549 cell lines. Results A549/cDDP was resistant to many anti-tumor agents. The IC50 of A549/cDDP was 16.87 times higher than that of A549. The expressions of P-gp and MRP in A549/cDDP were increased significantly to (70.5±4.9% and (29.4±2.9%, respectively, vs (42.4±5.6% and (21.4±3.5% in A549. There was no difference of the GSH/GST expression between A549/cDDPand A549 cells. Conclusion A549/cDDP is a model with multidrug resistance and the levels of MDR and MRP mRNA expressions are remarkably higher in A549/cDDP than those in A549.

  3. Cytokine-induced killer cells showing multidrug resistance and remaining cytotoxic activity to tumor cells after transfected with mdr1 cDNA

    Institute of Scientific and Technical Information of China (English)

    李惠芳; 杨永红; 石永进; 王逸群; 朱平

    2004-01-01

    Background Routine treatment of cancer such as surgery, radiation or chemotherapy is sometimes unable to erdiacate metastatic malignant cells. So we tried a new method and increased the adoptive immunotherapy of Cytokine-induced killer (CIK) cells in tumor patients and the multidrug resistance (mdr1) cDNA was transfected into CIK cells. Methods CIK cells were obtained from peripheral blood and induced by IFN-γ, anti-CD3 monoclonal antibody, IL-2 and IL-1. CIK cells were transfected with plasmid PHaMDR containing human mdr1 cDNA by electroporation. RT-PCR was used to detect mdr1 mRNA in transfected CIK cells. P-glycoprotein (P-gp) expressed on surface of CIK cells was assayed by FITC-conjugated anti-P-gp monoclonal antibody and flow cytometry. Multidrug resistance to doxorubicin and colchicine and cytotoxic activity to human breast cancer cell line MCF7 were performed using MTT method.Results mdr1 mRNA was detected in transfected CIK cells. P-gp was expressed on the surface of the transfected CIK cells, and the P-gp positive cells reached 21%-37% of the total CIK cells after transfection. The IC50 to doxorubicin increased to 22.3-45.8 times, and that to colchicines to 6.7-11.35 times, as compared to those of untransfected CIK cells. However, the cytotoxic activity to MCF7 cell line remained unaltered.Conclusions CIK cells were successfully transfected with mdr1 cDNA by using electroporation. The transfected CIK cells had the characteristics of multidrug resistance without change in their cytotoxic activity to tumor cells.

  4. 耐药相关蛋白P-gp、MRP、LRP在非小细胞肺癌组织中的表达及意义%The expression and significance of the multidrug resistance-related proteins P-gp, MRP and LRP in human non-small cell lung cancer tissues

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Objective: To explore the expression and significance of the multidrug resistance-related proteins P-glycoprotein (P-gp), multidrug resistance-related protein (MRP), lung resistance protein (LRP) in human non-small cell lung cancer (NSCLC) tissues and paratumor tissues. Methods: Immunohistochemistry (IHC) was used to examine the expression level of proteins P-gp, MRP and LRP in 43 samples of NSCLC and 15 samples of paratumor tissues. Results: The expression rates of P-gp, MRP and LRP in 43 tumor tissues were 74.42% (32/43), 67.44% (29/43) and 88.37% (38/43), respectively, while in 15 paratumor tissues were 13.33% (2/15), 20.00% (3/15) and 6.67% (1/15), respectively. There was significant difference in the expression of proteins (P-gp, MRP and LRP) between lung cancer tissues and paratumor tissues (P < 0.05). The expression of proteins P-gp, LRP in lung adenocarcinoma were higher than that in other pathological carcinomas (P < 0.05). The expression of protein MRP was not related to pathological type, clinical stage and classification of histodifferentiation (P >0.05). Conclusion: Multidrug resistance is more common in NSCLC. The proteins of P-gp, MRP and LRP participated in the formation of multidrug resistance in lung cancer. Detection of multidrug resistance-related proteins in lung cancer tissues may be useful to choice drugs.

  5. Susceptibility of multidrug resistant clinical pathogens to a chlorhexidine formulation.

    Science.gov (United States)

    Günther, F; Kaiser, S J; Fries, T; Frank, U; Mutters, N T

    2015-01-01

    Multidrug resistant pathogens are a widespread problem in the hospital setting especially on intensive care units (ICU). This study evaluated the susceptibility of clinical isolates of gramnegative extensively drug resistant organisms (XDR), methicillinresistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococcus (VRE) to a proprietary chlorhexidine digluconate (CHG) formulation used in one brand of CHG-impregnated cloths. Ten isolates each of XDR Pseudomonas aeruginosa, XDR Acinetobacter baumannii, XDR Klebsiella pneumoniae, XDR Escherichia coli, MRSA, and vancomycin-resistant Enterococcus faecium from our hospital were tested. All isolates were susceptible to the proprietary CHG formulation (0.5%, 1%, 2%), with 99% to 100% suppression of growth at the earliest time point in time kill assays (1 minute for gram-positive and 15 seconds for gram-negative organisms). Minimum inhibitory concentrations ranged from 1 : 4096 to 1 : 65536 for MRSA, 1 : 1024 to 1 : 2048 for VRE, 1 : 2048 to 1 : 4096 for XDR E. coli, 1 : 512 to 1 : 2048 for XDR A. baumannii, 1 : 512 to 1 : 1024 for XDR P. aeruginosa, and 1 : 512 to 1 : 1024 for XDR K. pneumoniae. Cloths impregnated with this CHG formulation provide effective protection against colonization and infection by many pathogens. This study provides in vitro evidence that the proprietary CHG formulation used in one brand of CHG-impregnated cloths is effective against XDR gram-negative organisms, MRSA, and VRE.

  6. Imaging multidrug resistance with 4-[18F]fluoropaclitaxel.

    Science.gov (United States)

    Kurdziel, Karen A; Kalen, Joseph D; Hirsch, Jerry I; Wilson, John D; Agarwal, Rakesh; Barrett, Daniel; Bear, Harry D; McCumiskey, James F

    2007-10-01

    Multidrug resistance (MDR) is a cause of treatment failure in many cancer patients. MDR refers to a phenotype whereby a tumor is resistant to a large number of natural chemotherapeutic drugs. Having prior knowledge of the presence of such resistance would decrease morbidity from unsuccessful therapy and allow for the selection of individuals who may benefit from the coadministration of MDR-inhibiting drugs. The Tc-99m-labeled single-photon-emitting radiotracers sestamibi and tetrofosmin have shown some predictive value. However, positron-emitting radiotracers, which allow for dynamic quantitative imaging, hold promise for a more accurate and specific identification of MDRtumors.MDR-expressing tumors are resistant to paclitaxel, which is commonly used as a chemotherapeutic agent. 4-[18F]Fluoropaclitaxel (FPAC) is a PET-radiolabeled analogue of paclitaxel. Preclinical studies have shown the uptake of FPAC to be inversely proportional to tumor MDR expression. FPAC PET imaging in normal volunteers shows biodistribution to be similar to that in nonhuman primates. Imaging in a breast cancer patient showed FPAC localization in a primary tumor that responded to chemotherapy, while failure to localize in mediastinal disease corresponded with only partial response.FPAC PET imaging shows promise for the noninvasive pretreatment identification of MDR-expressing tumors. While much additional work is needed, this work represents a step toward image-guided personalized medicine.

  7. Imaging multidrug resistance with 4-[{sup 18}F]fluoropaclitaxel

    Energy Technology Data Exchange (ETDEWEB)

    Kurdziel, Karen A. [Department of Radiology, Virginia Commonwealth University, Richmond, VA (United States)], E-mail: kurdziel@vcu.edu; Kalen, Joseph D. [School of Medicine, Virginia Commonwealth University, Richmond, VA (United States)], E-mail: jdkalen@vcu.edu; Hirsch, Jerry I. [School of Medicine, Virginia Commonwealth University, Richmond, VA (United States)], E-mail: jihirsch@vcu.edu; Wilson, John D. [School of Medicine, Virginia Commonwealth University, Richmond, VA (United States)], E-mail: wilsonjd@hsc.vcu.edu; Agarwal, Rakesh [Surgical Oncology, Virginia Commonwealth University, Richmond, VA (United States)], E-mail: dbarrett@vcu.edu; Barrett, Daniel [School of Medicine, Virginia Commonwealth University, Richmond, VA (United States)], E-mail: ragarwal@vcu.edu; Bear, Harry D. [Surgical Oncology, Virginia Commonwealth University, Richmond, VA (United States)], E-mail: 9jmccumi@mail2.vcu.edu; McCumiskey, James F. [Department of Radiology, Virginia Commonwealth University, Richmond, VA (United States)], E-mail: hbear@hsc.vcu.edu

    2007-10-15

    Multidrug resistance (MDR) is a cause of treatment failure in many cancer patients. MDR refers to a phenotype whereby a tumor is resistant to a large number of natural chemotherapeutic drugs. Having prior knowledge of the presence of such resistance would decrease morbidity from unsuccessful therapy and allow for the selection of individuals who may benefit from the coadministration of MDR-inhibiting drugs. The Tc-99m-labeled single-photon-emitting radiotracers sestamibi and tetrofosmin have shown some predictive value. However, positron-emitting radiotracers, which allow for dynamic quantitative imaging, hold promise for a more accurate and specific identification of MDRtumors.MDR-expressing tumors are resistant to paclitaxel, which is commonly used as a chemotherapeutic agent. 4-[{sup 18}F]Fluoropaclitaxel (FPAC) is a PET-radiolabeled analogue of paclitaxel. Preclinical studies have shown the uptake of FPAC to be inversely proportional to tumor MDR expression. FPAC PET imaging in normal volunteers shows biodistribution to be similar to that in nonhuman primates. Imaging in a breast cancer patient showed FPAC localization in a primary tumor that responded to chemotherapy, while failure to localize in mediastinal disease corresponded with only partial response.FPAC PET imaging shows promise for the noninvasive pretreatment identification of MDR-expressing tumors. While much additional work is needed, this work represents a step toward image-guided personalized medicine.

  8. Multidrug-resistant tuberculosis and migration to Europe

    DEFF Research Database (Denmark)

    Hargreaves, S; Lönnroth, K; Nellums, L B

    2016-01-01

    Multidrug-resistant tuberculosis (MDR-TB) in low-incidence countries in Europe is more prevalent among migrants than the native population. The impact of the recent increase in migration to EU and EEA countries with a low incidence of TB (<20 cases per 100 000) on MDR-TB epidemiology is unclear. ...... to treat and prevent MDR-TB among migrants in Europe. An evidence-base is urgently needed to inform guidelines for effective approaches for MDR-TB management in migrant populations in Europe....... outcomes. Although concerns have been raised around 'health tourists' migrating for MDR-TB treatment, numbers are probably small and data are lacking. Migrants experience significant barriers to testing and treatment for MDR-TB, exacerbated by increasingly restrictive health systems. Screening for latent...

  9. Preparation of silver nanoparticles fabrics against multidrug-resistant bacteria

    Science.gov (United States)

    Hanh, Truong Thi; Thu, Nguyen Thi; Hien, Nguyen Quoc; An, Pham Ngoc; Loan, Truong Thi Kieu; Hoa, Phan Thi

    2016-04-01

    The silver nanoparticles (AgNPs)/peco fabrics were prepared by immobilization of AgNPs on fabrics in which AgNPs were synthesized by γ-irradiation of the 10 mM AgNO3 chitosan solution at the dose of 17.6 kGy. The AgNPs size has been estimated to be about 11 nm from TEM image. The AgNPs content onto peco fabrics was of 143±6 mg/kg at the initial AgNPs concentration of 100 ppm. The AgNPs colloidal solution was characterized by UV-vis spectroscopy and TEM image. The antibacterial activity of AgNPs/peco fabrics after 60 washings against Staphylococcus aureus and Klebsiella pneumoniae was found to be over 99%. Effects of AgNPs fabics on multidrug-resistant pathogens from the clinical specimens were also tested.

  10. Bacteriophages: biosensing tools for multi-drug resistant pathogens.

    Science.gov (United States)

    Tawil, N; Sacher, E; Mandeville, R; Meunier, M

    2014-03-21

    Pathogen detection is of utmost importance in many sectors, such as in the food industry, environmental quality control, clinical diagnostics, bio-defence and counter-terrorism. Failure to appropriately, and specifically, detect pathogenic bacteria can lead to serious consequences, and may ultimately be lethal. Public safety, new legislation, recent outbreaks in food contamination, and the ever-increasing prevalence of multidrug-resistant infections have fostered a worldwide research effort targeting novel biosensing strategies. This review concerns phage-based analytical and biosensing methods targeted towards theranostic applications. We discuss and review phage-based assays, notably phage amplification, reporter phage, phage lysis, and bioluminescence assays for the detection of bacterial species, as well as phage-based biosensors, including optical (comprising SPR sensors and fiber optic assays), electrochemical (comprising amperometric, potentiometric, and impedimetric sensors), acoustic wave and magnetoelastic sensors.

  11. Treatment strategy based on targeting P-glycoprotein on peripheral lymphocytes in patients with systemic autoimmune disease.

    Science.gov (United States)

    Tsujimura, Shizuyo; Tanaka, Yoshiya

    2012-02-01

    Although corticosteroids, immunosuppressants and disease-modifying antirheumatic drugs (DMARDs) are widely used in the treatment of various systemic autoimmune diseases such as systemic lupus erythematosus (SLE), we often experience patients with systemic autoimmune diseases who are resistant to these treatments. P-glycoprotein (P-gp) of membrane transporters, a product of the multiple drug resistance (MDR)-1 gene, is known to play a pivotal role in the acquisition of drug resistance to chemotherapy in malignancy. However, the relevance of MDR-1 and P-gp to resting and activated lymphocytes, which are the major target in the treatment of systemic autoimmune diseases, remains unclear. Studies from our laboratories found surface expression of P-gp on peripheral lymphocytes in patients with SLE and a significant correlation between the expression level and disease activity. Such expression is induced not only by genotoxic stresses but also by various stimuli including cytokines, resulting in active efflux of drugs from the cytoplasm of lymphocytes, resulting in drug-resistance and high disease activity. However, the use of both P-gp antagonists (e.g., cyclosporine) and inhibition of P-gp synthesis with intensive immunosuppressive therapy successfully reduces the efflux of corticosteroids from lymphocytes in vitro, suggesting that P-gp antagonists and P-gp synthesis inhibitors could be used to overcome drug-resistance in vivo and improve outcome. In conclusion, lymphocytes activated by various stimuli in patients with highly active disease apparently acquire MDR-1-mediated multidrug resistance against corticosteroids and probably some DMARDs, which are substrates of P-gp. Inhibition/reduction of P-gp could overcome such drug resistance. The expression of P-gp on lymphocytes is a promising marker of drug resistance and a suitable target to combat drug resistance in patients with active systemic autoimmune diseases.

  12. Molecular model of the outward facing state of the human P-glycoprotein (ABCB1, and comparison to a model of the human MRP5 (ABCC5

    Directory of Open Access Journals (Sweden)

    Sager Georg

    2007-09-01

    Full Text Available Abstract Background Multidrug resistance is a particular limitation to cancer chemotherapy, antibiotic treatment and HIV medication. The ABC (ATP binding cassette transporters human P-glycoprotein (ABCB1 and the human MRP5 (ABCC5 are involved in multidrug resistance. Results In order to elucidate structural and molecular concepts of multidrug resistance, we have constructed a molecular model of the ATP-bound outward facing conformation of the human multidrug resistance protein ABCB1 using the Sav1866 crystal structure as a template, and compared the ABCB1 model with a previous ABCC5 model. The electrostatic potential surface (EPS of the ABCB1 substrate translocation chamber, which transports cationic amphiphilic and lipophilic substrates, was neutral with negative and weakly positive areas. In contrast, EPS of the ABCC5 substrate translocation chamber, which transports organic anions, was generally positive. Positive-negative ratios of amino acids in the TMDs of ABCB1 and ABCC5 were also analyzed, and the positive-negative ratio of charged amino acids was higher in the ABCC5 TMDs than in the ABCB1 TMDs. In the ABCB1 model residues Leu65 (transmembrane helix 1 (TMH1, Ile306 (TMH5, Ile340 (TMH6 and Phe343 (TMH6 may form a binding site, and this is in accordance with previous site directed mutagenesis studies. Conclusion The Sav1866 X-ray structure may serve as a suitable template for the ABCB1 model, as it did with ABCC5. The EPS in the substrate translocation chambers and the positive-negative ratio of charged amino acids were in accordance with the transport of cationic amphiphilic and lipophilic substrates by ABCB1, and the transport of organic anions by ABCC5.

  13. The Transmission Interfaces Contribute Asymmetrically to the Assembly and Activity of Human P-glycoprotein.

    Science.gov (United States)

    Loo, Tip W; Clarke, David M

    2015-07-01

    P-glycoprotein (P-gp; ABCB1) is an ABC drug pump that protects us from toxic compounds. It is clinically important because it confers multidrug resistance. The homologous halves of P-gp each contain a transmembrane (TM) domain (TMD) with 6 TM segments followed by a nucleotide-binding domain (NBD). The drug- and ATP-binding sites reside at the interface between the TMDs and NBDs, respectively. Each NBD is connected to the TMDs by a transmission interface involving a pair of intracellular loops (ICLs) that form ball-and-socket joints. P-gp is different from CFTR (ABCC7) in that deleting NBD2 causes misprocessing of only P-gp. Therefore, NBD2 might be critical for stabilizing ICLs 2 and 3 that form a tetrahelix bundle at the NBD2 interface. Here we report that the NBD1 and NBD2 transmission interfaces in P-gp are asymmetric. Point mutations to 25 of 60 ICL2/ICL3 residues at the NBD2 transmission interface severely reduced P-gp assembly while changes to the equivalent residues in ICL1/ICL4 at the NBD1 interface had little effect. The hydrophobic nature at the transmission interfaces was also different. Mutation of Phe-1086 or Tyr-1087 to arginine at the NBD2 socket blocked activity or assembly while the equivalent mutations at the NBD1 socket had only modest effects. The results suggest that the NBD transmission interfaces are asymmetric. In contrast to the ICL2/3-NBD2 interface, the ICL1/4-NBD1 transmission interface is more hydrophilic and insensitive to mutations. Therefore the ICL2/3-NBD2 transmission interface forms a precise hydrophobic connection that acts as a linchpin for assembly and trafficking of P-gp.

  14. Modulation of P-glycoprotein efflux pump: induction and activation as a therapeutic strategy.

    Science.gov (United States)

    Silva, Renata; Vilas-Boas, Vânia; Carmo, Helena; Dinis-Oliveira, Ricardo Jorge; Carvalho, Félix; de Lourdes Bastos, Maria; Remião, Fernando

    2015-05-01

    P-glycoprotein (P-gp) is an ATP-dependent efflux pump encoded by the MDR1 gene in humans, known to mediate multidrug resistance of neoplastic cells to cancer therapy. For several decades, P-gp inhibition has drawn many significant research efforts in an attempt to overcome this phenomenon. However, P-gp is also constitutively expressed in normal human epithelial tissues and, due to its broad substrate specificity, to its cellular polarized expression in many excretory and barrier tissues, and to its great efflux capacity, it can play a crucial role in limiting the absorption and distribution of harmful xenobiotics, by decreasing their intracellular accumulation. Such a defense mechanism can be of particular relevance at the intestinal level, by significantly reducing the intestinal absorption of the xenobiotic and, consequently, avoiding its access to the target organs. In this review, the current knowledge on this important efflux pump is summarized, and a new focus is brought on the therapeutic interest of inducing and/or activating P-gp for limiting the toxicity caused by its substrates. Several in vivo and in vitro studies validating the use of such a therapeutic strategy are discussed. An extensive literature search for reported P-gp inducers/activators and for the experimental models used in their characterization was conducted. Those studies demonstrate that effective antidotal pathways can be achieved by efficiently promoting the P-gp-mediated efflux of deleterious xenobiotics, resulting in a significant reduction in their intracellular levels and, consequently, in a significant reduction of their toxicity.

  15. Human P-glycoprotein exhibits reduced affinity for substrates during a catalytic transition state.

    Science.gov (United States)

    Ramachandra, M; Ambudkar, S V; Chen, D; Hrycyna, C A; Dey, S; Gottesman, M M; Pastan, I

    1998-04-01

    Human P-glycoprotein (Pgp), a plasma membrane protein that confers multidrug resistance, functions as an ATP-dependent drug efflux pump. Pgp contains two ATP binding/utilization sites and exhibits ATPase activity that is stimulated in the presence of substrates and modulating agents. The mechanism of coupling of ATP hydrolysis to drug transport is not known. To understand the role of ATP hydrolysis in drug binding, it is necessary to develop methods for purifying and reconstituting Pgp that retains properties including stimulation of ATPase activity by known substrates to an extent similar to that in the native membrane. In this study, (His)6-tagged Pgp was expressed in Trichoplusia ni (High Five) cells using the recombinant baculovirus system and purified by metal affinity chromatography. Upon reconstitution into phospholipid vesicles, purified Pgp exhibited specific binding to analogues of substrates and ATP in affinity labeling experiments and displayed a high level of drug-stimulated ATPase activity (specific activity ranging from 4.5 to 6.5 micromol min-1 mg-1). The ATPase activity was inhibited by ADP in a competitive manner, and by vanadate and N-ethylmaleimide at low concentrations. Vanadate which is known to inhibit ATPase activity by trapping MgADP at the catalytic site inhibited photoaffinity labeling of Pgp with substrate analogues, [125I]iodoarylazidoprazosin and [3H]azidopine, only under ATP hydrolysis conditions. Because vanadate-trapped Pgp is known to resemble the ADP and phosphate-bound catalytic transition state, our findings indicate that ATP hydrolysis results in a conformation with reduced affinity for substrates. A catalytic transition conformation with reduced affinity would essentially result in substrate dissociation and supports a model for drug transport in which an ATP hydrolysis-induced conformational change leads to drug release toward the extracellular medium.

  16. Prediction of promiscuous p-glycoprotein inhibition using a novel machine learning scheme.

    Directory of Open Access Journals (Sweden)

    Max K Leong

    Full Text Available BACKGROUND: P-glycoprotein (P-gp is an ATP-dependent membrane transporter that plays a pivotal role in eliminating xenobiotics by active extrusion of xenobiotics from the cell. Multidrug resistance (MDR is highly associated with the over-expression of P-gp by cells, resulting in increased efflux of chemotherapeutical agents and reduction of intracellular drug accumulation. It is of clinical importance to develop a P-gp inhibition predictive model in the process of drug discovery and development. METHODOLOGY/PRINCIPAL FINDINGS: An in silico model was derived to predict the inhibition of P-gp using the newly invented pharmacophore ensemble/support vector machine (PhE/SVM scheme based on the data compiled from the literature. The predictions by the PhE/SVM model were found to be in good agreement with the observed values for those structurally diverse molecules in the training set (n = 31, r(2 = 0.89, q(2 = 0.86, RMSE = 0.40, s = 0.28, the test set (n = 88, r(2 = 0.87, RMSE = 0.39, s = 0.25 and the outlier set (n = 11, r(2 = 0.96, RMSE = 0.10, s = 0.05. The generated PhE/SVM model also showed high accuracy when subjected to those validation criteria generally adopted to gauge the predictivity of a theoretical model. CONCLUSIONS/SIGNIFICANCE: This accurate, fast and robust PhE/SVM model that can take into account the promiscuous nature of P-gp can be applied to predict the P-gp inhibition of structurally diverse compounds that otherwise cannot be done by any other methods in a high-throughput fashion to facilitate drug discovery and development by designing drug candidates with better metabolism profile.

  17. Multidrug resistance and ESBL-producing Salmonella spp. isolated from broiler processing plants.

    Science.gov (United States)

    Ziech, Rosangela Estel; Lampugnani, Camila; Perin, Ana Paula; Sereno, Mallu Jagnow; Sfaciotte, Ricardo Antônio Pilegi; Viana, Cibeli; Soares, Vanessa Mendonça; Pinto, José Paes de Almeida Nogueira; Bersot, Luciano dos Santos

    2016-01-01

    The aim of this study was to investigate the occurrence of multidrug-resistant, extended spectrum beta-lactamase (ESBL) producing Salmonella spp. isolated from conveyor belts of broiler cutting rooms in Brazilian broiler processing plants. Ninety-eight strains of Salmonella spp. were analyzed. Multidrug resistance was determined by the disk diffusion test and the susceptibility of the isolated bacteria was evaluated against 18 antimicrobials from seven different classes. The double disk diffusion test was used to evaluate ESBL production. Of the 98 strains tested, 84 were multidrug resistant. The highest rates of resistance were against nalidixic acid (95%), tetracycline (91%), and the beta-lactams: ampicillin and cefachlor (45%), followed by streptomycin and gentamicin with 19% and 15% of strain resistance, respectively. By contrast, 97% of the strains were sensitive to chloramphenicol. 45% of the strains were positive for the presence of ESBL activity. In this study, high rates of multidrug resistance and ESBL production were observed in Salmonella spp.

  18. Brain accumulation of the EML4-ALK inhibitor ceritinib is restricted by P-glycoprotein (P-GP/ABCB1) and breast cancer resistance protein (BCRP/ABCG2)

    NARCIS (Netherlands)

    Kort, Anita; Sparidans, Rolf; Wagenaar, Els; Beijnen, Jacob; Schinkel, Alfred H.

    2015-01-01

    We aimed to clarify the roles of the multidrug transporters ABCB1 and ABCG2 in oral availability and brain accumulation of ceritinib, an oral anaplastic lymphoma kinase (ALK) inhibitor used to treat metastatic non-small cell lung cancer (NSCLC) after progression on crizotinib. Importantly, NSCLC is

  19. MiR-466b-1-3p regulates P-glycoprotein expression in rat cerebral microvascular endothelial cells.

    Science.gov (United States)

    Yang, Xiaobo; Ren, Weimin; Shao, Yiye; Chen, Yinghui

    2017-04-03

    Epilepsy is one of the most common neurological disorders, and approximately one-third of epilepsy cases are resistant to treatment with anti-epileptic drug (AED). P-glycoprotein (P-gp) is a multi-drug transporter that is thought to play a pivotal role in multiple drug resistance (MDR) in epilepsy. The regulatory mechanism of P-gp remains largely unknown; however, recent studies have demonstrated that microRNAs (miRNAs) may regulate the chemo-resistance mediated by P-gp. This study investigated the effect of specific miRNAs that regulate P-gp expression in rat cerebral microvascular endothelial cells (RCMECs). Primary cultures of RCMECs were treated with phenobarbital (PB) at various concentrations to induce P-gp overexpression. MiRNA microarrays were used to investigate the expression profiles of miRNAs in the resistant RCMECs induced by PB and corresponding non-resistant cells. Our data demonstrated decreased miR-466b-1-3p expression in the resistant cells compared with the non-resistant cells. Moreover, the recombinant RNA of 466b-1-3p (mimic) and the artificial antisense RNA of miR-466b-1-3p (inhibitor) were constructed and transfected into resistant RCMECs. The expression and function of P-gp were measured by Western blotting, quantitative real-time polymerase chain reaction (qRT-PCR) and flow cytometry using rhodamine efflux. The mRNA and protein levels of P-gp increased as the concentration of PB increased, whereas miR-466b-1-3p levels decreased with increasing PB concentrations (Pp mimic down-regulated P-gp expression, whereas the miR-466b-1-3p inhibitor up-regulated P-gp expression (Pp may regulate PB-induced P-gp expression in RCMECs.

  20. "Emergence of Multidrug Resistant Strains of Escherichia coli Isolated from Urinary Tract Infections"

    OpenAIRE

    R Moniri; Khorshidi, A; H Akbari

    2003-01-01

    The emergence of multidrug resistant strains of Escherichia coli has complicated treatment decision and may lead to treatment failures. From April to November 2001 we prospectively evaluated the prevalence of resistance to trimethoprim-sulfamethoxazole (SXT), gentamicin, cephalothin, ciprofloxacin, and nitrofurantoin in 220 Escherichia coli isolates from patients with urinary tract infections in kashan, Iran. To assess the current breadth of multidrug resistance among urinary isolates of E. c...

  1. Synthesis, biological evaluation and 3D-QSAR studies of new chalcone derivatives as inhibitors of human P-glycoprotein.

    Science.gov (United States)

    Parveen, Zahida; Brunhofer, Gerda; Jabeen, Ishrat; Erker, Thomas; Chiba, Peter; Ecker, Gerhard F

    2014-04-01

    P-glycoprotein (P-gp) is an ATP-dependent multidrug resistance efflux transporter that plays an important role in anticancer drug resistance and in pharmacokinetics of medicines. Despite a large number of structurally and functionally diverse compounds, also flavonoids and chalcones have been reported as inhibitors of P-gp. The latter share some similarity with the well studied class of propafenones, but do not contain a basic nitrogen atom. Furthermore, due to their rigidity, they are suitable candidates for 3D-QSAR studies. In this study, a set of 22 new chalcone derivatives were synthesized and evaluated in a daunomycin efflux inhibition assay using the CCRF.CEM.VCR1000 cell line. The compound 10 showed the highest activity (IC50=42nM), which is one order of magnitude higher than the activity for an equilipohillic propafenone analogue. 2D- and 3D-QSAR studies indicate the importance of H-bond acceptors, methoxy groups, hydrophobic groups as well as the number of rotatable bonds as pharmacophoric features influencing P-gp inhibitory activity.

  2. Nanodrugs: optimism for emerging trend of multidrug resistance

    Directory of Open Access Journals (Sweden)

    Khan AU

    2012-08-01

    Full Text Available Asad U KhanMedical Microbiology and Molecular Biology Laboratory, Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, IndiaThis is with reference to an article published recently in your journal regarding the antibiotic activity of chitosan-coated silver nanoparticles.1 This is an inspiring move towards control of infection caused by multidrug-resistant bacteria which has become a serious problem for clinicians and physicians worldwide.2 At the moment, carbapenems are being used as the drugs of choice to combat infections. However, the emergence of carbapenem resistance has changed current remedial approaches in the management of serious infections. One of the latest enzymes, NDM-1 (New Delhi metallo-β-lactamase-1, first identified in a Swedish patient of Indian origin in 2008,3 has been key in the development of resistance to almost all antibiotics. Infection caused by NDM-1 producers is widespread on the Indian subcontinent,4 and is now emerging in the US and other countries throughout the world.5View original paper by Jena and colleagues.

  3. [Multidrug-resistant tuberculosis: challenges of a global emergence].

    Science.gov (United States)

    Comolet, T

    2015-10-01

    Drug-resistant tuberculosis, in particular Multi-Drug Resistant (MDR-TB) is an increasing global concern and a major burden for some developing countries, especially the BRICS. It is assumed that every year roughly 350 000 new MDR-TB cases occur in the world, on average in 20.5% of TB patients that have been previously treated but also in 3.5% of persons that have never been on TB treatment before. The global distribution of cases is very heterogeneous and is now better understood thanks to a growing number of specific surveys and routine surveillance systems: incidence is much higher in southern Africa and in all countries formerly part of the USSR. Countries with weak health systems and previously inefficient TB control programs are highly vulnerable to MDR epidemics because program failures do help creating, maintaining and spreading resistances. Global response is slowly rolled out and diagnosis capacities are on the rise (mostly with genotypic methods) but adequate and successful treatment and care is still limited to a minority of global cases. From a public health perspective the MDR-TB growing epidemics will not be controlled merely by the introduction of few new antibiotics because it is also linked to patient's compliance and adequate case management supported by efficient TB program. In depth quality improvement will only be achieved after previous errors are thoroughly analyzed and boldly corrected.

  4. α-Tocopherols modify the membrane dipole potential leading to modulation of ligand binding by P-glycoprotein

    OpenAIRE

    Davis, Sterenn; Davis, Benjamin M.; Richens, Joanna L.; Vere, Kelly-Ann; Petrov, Peter G.; Winlove, C. Peter; O’Shea, Paul

    2015-01-01

    α-Tocopherol (vitamin E) has attracted considerable attention as a potential protective or palliative agent. In vitro, its free radical-scavenging antioxidant action has been widely demonstrated. In vivo, however, vitamin E treatment exhibits negligible benefits against oxidative stress. α-Tocopherol influences lipid ordering within biological membranes and its derivatives have been suggested to inhibit the multi-drug efflux pump, P-glycoprotein (P-gp). This study employs the fluorescent memb...

  5. Higher Desolvation Energy Reduces Molecular Recognition in Multi-Drug Resistant HIV-1 Protease

    Directory of Open Access Journals (Sweden)

    Ladislau C. Kovari

    2012-05-01

    Full Text Available Designing HIV-1 protease inhibitors that overcome drug-resistance is still a challenging task. In this study, four clinical isolates of multi-drug resistant HIV-1 proteases that exhibit resistance to all the US FDA-approved HIV-1 protease inhibitors and also reduce the substrate recognition ability were examined. A multi-drug resistant HIV-1 protease isolate, MDR 769, was co-crystallized with the p2/NC substrate and the mutated CA/p2 substrate, CA/p2 P1’F. Both substrates display different levels of molecular recognition by the wild-type and multi-drug resistant HIV-1 protease. From the crystal structures, only limited differences can be identified between the wild-type and multi-drug resistant protease. Therefore, a wild-type HIV-1 protease and four multi-drug resistant HIV-1 proteases in complex with the two peptides were modeled based on the crystal structures and examined during a 10 ns-molecular dynamics simulation. The simulation results reveal that the multi-drug resistant HIV-1 proteases require higher desolvation energy to form complexes with the peptides. This result suggests that the desolvation of the HIV-1 protease active site is an important step of protease-ligand complex formation as well as drug resistance. Therefore, desolvation energy could be considered as a parameter in the evaluation of future HIV-1 protease inhibitor candidates.

  6. Quantitative assessment of p-glycoprotein expression and function using confocal image analysis.

    Science.gov (United States)

    Hamrang, Zahra; Arthanari, Yamini; Clarke, David; Pluen, Alain

    2014-10-01

    P-glycoprotein is implicated in clinical drug resistance; thus, rapid quantitative analysis of its expression and activity is of paramout importance to the design and success of novel therapeutics. The scope for the application of quantitative imaging and image analysis tools in this field is reported here at "proof of concept" level. P-glycoprotein expression was utilized as a model for quantitative immunofluorescence and subsequent spatial intensity distribution analysis (SpIDA). Following expression studies, p-glycoprotein inhibition as a function of verapamil concentration was assessed in two cell lines using live cell imaging of intracellular Calcein retention and a routine monolayer fluorescence assay. Intercellular and sub-cellular distributions in the expression of the p-glycoprotein transporter between parent and MDR1-transfected Madin-Derby Canine Kidney cell lines were examined. We have demonstrated that quantitative imaging can provide dose-response parameters while permitting direct microscopic analysis of intracellular fluorophore distributions in live and fixed samples. Analysis with SpIDA offers the ability to detect heterogeniety in the distribution of labeled species, and in conjunction with live cell imaging and immunofluorescence staining may be applied to the determination of pharmacological parameters or analysis of biopsies providing a rapid prognostic tool.

  7. Molecular characterization of multidrug-resistant Klebsiella pneumoniae isolates

    Directory of Open Access Journals (Sweden)

    Xiang-hua Hou

    2015-09-01

    Full Text Available Klebsiella pneumoniae is an important cause of healthcare-associated infections worldwide. Selective pressure, the extensive use of antibiotics, and the conjugational transmission of antibiotic resistance genes across bacterial species and genera facilitate the emergence of multidrug-resistant (MDR K. pneumoniae. Here, we examined the occurrence, phenotypes and genetic features of MDR K. pneumoniae isolated from patients in intensive care units (ICUs at the First Affiliated Hospital of Xiamen University in Xiamen, China, from January to December 2011. Thirty-eight MDR K. pneumoniae strains were collected. These MDR K. pneumoniae isolates possessed at least seven antibiotic resistance determinants, which contribute to the high-level resistance of these bacteria to aminoglycosides, macrolides, quinolones and β-lactams. Among these isolates, 24 strains were extended-spectrum β-lactamase (ESBL producers, 2 strains were AmpC producers, and 12 strains were both ESBL and AmpC producers. The 38 MDR isolates also contained class I (28/38 and class II integrons (10/38. All 28 class I-positive isolates contained aacC1, aacC4, orfX, orfX’ and aadA1 genes. β-lactam resistance was conferred through blaSHV (22/38, blaTEM (10/38, and blaCTX-M (7/38. The highly conserved blaKPC-2 (37/38 and blaOXA-23(1/38 alleles were responsible for carbapenem resistance, and a gyrAsite mutation (27/38 and the plasmid-mediated qnrB gene (13/38 were responsible for quinolone resistance. Repetitive-sequence-based PCR (REP-PCR fingerprinting of these MDR strains revealed the presence of five groups and sixteen patterns. The MDR strains from unrelated groups showed different drug resistance patterns; however, some homologous strains also showed different drug resistance profiles. Therefore, REP-PCR-based analyses can provide information to evaluate the epidemic status of nosocomial infection caused by MDR K. pneumoniae; however, this test lacks the power to discriminate some

  8. Molecular characterization of multidrug-resistant Klebsiella pneumoniae isolates.

    Science.gov (United States)

    Hou, Xiang-hua; Song, Xiu-yu; Ma, Xiao-bo; Zhang, Shi-yang; Zhang, Jia-qin

    2015-01-01

    Klebsiella pneumoniae is an important cause of healthcare-associated infections worldwide. Selective pressure, the extensive use of antibiotics, and the conjugational transmission of antibiotic resistance genes across bacterial species and genera facilitate the emergence of multidrug-resistant (MDR) K. pneumoniae. Here, we examined the occurrence, phenotypes and genetic features of MDR K. pneumoniae isolated from patients in intensive care units (ICUs) at the First Affiliated Hospital of Xiamen University in Xiamen, China, from January to December 2011. Thirty-eight MDR K. pneumoniae strains were collected. These MDR K. pneumoniae isolates possessed at least seven antibiotic resistance determinants, which contribute to the high-level resistance of these bacteria to aminoglycosides, macrolides, quinolones and β-lactams. Among these isolates, 24 strains were extended-spectrum β-lactamase (ESBL) producers, 2 strains were AmpC producers, and 12 strains were both ESBL and AmpC producers. The 38 MDR isolates also contained class I (28/38) and class II integrons (10/38). All 28 class I-positive isolates contained aacC1, aacC4, orfX, orfX' and aadA1 genes. β-lactam resistance was conferred through bla SHV (22/38), bla TEM (10/38), and bla CTX-M (7/38). The highly conserved bla KPC-2 (37/38) and bla OXA-23(1/38) alleles were responsible for carbapenem resistance, and a gyrAsite mutation (27/38) and the plasmid-mediated qnrB gene (13/38) were responsible for quinolone resistance. Repetitive-sequence-based PCR (REP-PCR) fingerprinting of these MDR strains revealed the presence of five groups and sixteen patterns. The MDR strains from unrelated groups showed different drug resistance patterns; however, some homologous strains also showed different drug resistance profiles. Therefore, REP-PCR-based analyses can provide information to evaluate the epidemic status of nosocomial infection caused by MDR K. pneumoniae; however, this test lacks the power to discriminate some

  9. Antimicrobial resistance determinant microarray for analysis of multi-drug resistant isolates

    Science.gov (United States)

    Taitt, Chris Rowe; Leski, Tomasz; Stenger, David; Vora, Gary J.; House, Brent; Nicklasson, Matilda; Pimentel, Guillermo; Zurawski, Daniel V.; Kirkup, Benjamin C.; Craft, David; Waterman, Paige E.; Lesho, Emil P.; Bangurae, Umaru; Ansumana, Rashid

    2012-06-01

    The prevalence of multidrug-resistant infections in personnel wounded in Iraq and Afghanistan has made it challenging for physicians to choose effective therapeutics in a timely fashion. To address the challenge of identifying the potential for drug resistance, we have developed the Antimicrobial Resistance Determinant Microarray (ARDM) to provide DNAbased analysis for over 250 resistance genes covering 12 classes of antibiotics. Over 70 drug-resistant bacteria from different geographic regions have been analyzed on ARDM, with significant differences in patterns of resistance identified: genes for resistance to sulfonamides, trimethoprim, chloramphenicol, rifampin, and macrolide-lincosamidesulfonamide drugs were more frequently identified in isolates from sources in Iraq/Afghanistan. Of particular concern was the presence of genes responsible for resistance to many of the last-resort antibiotics used to treat war traumaassociated infections.

  10. 2'[(18)F]-fluoroethylrhodamine B is a promising radiotracer to measure P-glycoprotein function.

    Science.gov (United States)

    Trencsényi, György; Kertész, István; Krasznai, Zoárd T; Máté, Gábor; Szalóki, Gábor; Szabó Judit, P; Kárpáti, Levente; Krasznai, Zoltán; Márián, Teréz; Goda, Katalin

    2015-07-10

    In vivo detection of the emergence of P-glycoprotein (Pgp) mediated multidrug resistance in tumors could be beneficial for patients treated with anticancer drugs. PET technique in combination with appropriate radiotracers could be the most convenient method for detection of Pgp function. Rhodamine derivatives are validated fluorescent probes for measurement of mitochondrial membrane potential and also Pgp function. The aim of this study was to investigate whether 2'[(18)F]-fluoroethylrhodamine B ((18)FRB) a halogenated rhodamine derivative previously synthesized for PET assessment of myocardial perfusion preserved its Pgp substrate character. ATPase assay as well as accumulation experiments carried out using Pgp(+) and Pgp(-) human gynecologic (A2780/A2780(AD) and KB-3-1/KB-V1) and a mouse fibroblast cell pairs (NIH 3T3 and NIH 3T3 MDR1) were applied to study the interaction of (18)FRB with Pgp. ATPase assay proved that (18)FRB is a high affinity substrate of Pgp. Pgp(-) cells accumulated the (18)FRB rapidly in accordance with its lipophilic character. Dissipation of the mitochondrial proton gradient by a proton ionophore CCCP decreased the accumulation of rhodamine 123 (R123) and (18)FRB into Pgp(-) cells. Pgp(+) cells exhibited very low R123 and (18)FRB accumulation (around 1-8% of the Pgp(-) cell lines) which was not sensitive to the mitochondrial proton gradient; rather it was increased by the Pgp inhibitor cyclosporine A (CsA). Based on the above data we conclude that (18)FRB is a high affinity Pgp substrate and consequently a potential PET tracer to detect multidrug resistant tumors as well as the function of physiological barriers expressing Pgp.

  11. Effects of mefloquine use on Plasmodium vivax multidrug resistance.

    Science.gov (United States)

    Khim, Nimol; Andrianaranjaka, Voahangy; Popovici, Jean; Kim, Saorin; Ratsimbasoa, Arsene; Benedet, Christophe; Barnadas, Celine; Durand, Remy; Thellier, Marc; Legrand, Eric; Musset, Lise; Menegon, Michela; Severini, Carlo; Nour, Bakri Y M; Tichit, Magali; Bouchier, Christiane; Mercereau-Puijalon, Odile; Ménard, Didier

    2014-10-01

    Numerous studies have indicated a strong association between amplification of the multidrug resistance-1 gene and in vivo and in vitro mefloquine resistance of Plasmodium falciparum. Although falciparum infection usually is not treated with mefloquine, incorrect diagnosis, high frequency of undetected mixed infections, or relapses of P. vivax infection triggered by P. falciparum infections expose non-P. falciparum parasites to mefloquine. To assess the consequences of such unintentional treatments on P. vivax, we studied variations in number of Pvmdr-1 (PlasmoDB accession no. PVX_080100, NCBI reference sequence NC_009915.1) copies worldwide in 607 samples collected in areas with different histories of mefloquine use from residents and from travelers returning to France. Number of Pvmdr-1 copies correlated with drug use history. Treatment against P. falciparum exerts substantial collateral pressure against sympatric P. vivax, jeopardizing future use of mefloquine against P. vivax. A drug policy is needed that takes into consideration all co-endemic species of malaria parasites.

  12. What's new in multidrug-resistant pathogens in the ICU?

    Science.gov (United States)

    Zilahi, Gabor; Artigas, Antonio; Martin-Loeches, Ignacio

    2016-12-01

    Over the last several decades, antibacterial drug use has become widespread with their misuse being an ever-increasing phenomenon. Consequently, antibacterial drugs have become less effective or even ineffective, resulting in a global health security emergency. The prevalence of multidrug-resistant organisms (MDROs) varies widely among regions and countries. The primary aim of antibiotic stewardship programs is to supervise the three most influential factors contributing to the development and transmission of MDROs, namely: (1) appropriate antibiotic prescribing; (2) early detection and prevention of cross-colonization of MDROs; and (3) elimination of reservoirs. In the future, it is expected that a number of countries will experience a rise in MDROs. These infections will be associated with a high consumption of healthcare resources manifested by a prolonged hospital stay and high mortality. As a counteractive strategy, minimization of broad-spectrum antibiotic use and prompt antibiotic administration will aid in reduction of antibiotic resistance. Innovative management approaches include development and implementation of rapid diagnostic tests that will help in both shortening the duration of therapy and allowing early targeted therapy. The institution of more accessible therapeutic drug monitoring will help to optimize drug administration and support a patient-specific approach. Areas where further research is required are investigation into the heterogeneity of critically ill patients and the need for new antibacterial drug development.

  13. Biofilm formation in clinical isolates of nosocomial Acinetobacter baumannii and its relationship with multidrug resistance

    Directory of Open Access Journals (Sweden)

    Ebrahim Babapour

    2016-06-01

    Conclusions: Since most of the multidrug resistant strains produce biofilm, it seems necessary to provide continuous monitoring and determination of antibiotic susceptibility of clinical A. baumannii. This would help to select the most appropriate antibiotic for treatment.

  14. Impact of fungal drug transporters on fungicide sensitivity, multidrug resistance and virulence

    NARCIS (Netherlands)

    Waard, de M.A.; Andrade, A.C.; Hayashi, K.; Schoonbeek, H.; Stergiopoulos, I.; Zwiers, L.H.

    2006-01-01

    Drug transporters are membrane proteins that provide protection for organisms against natural toxic products and fungicides. In plant pathogens, drug transporters function in baseline sensitivity to fungicides, multidrug resistance (MDR) and virulence on host plants. This paper describes drug transp

  15. Ontogeny, aging, and gender-related changes in hepatic multidrug resistant protein genes in rats.

    Science.gov (United States)

    Zhu, Qiong-Ni; Hou, Wei-Yu; Xu, Shang-Fu; Lu, Yuan-Fu; Liu, Jie

    2017-02-01

    Multidrug resistance proteins (Mrps) are efflux transporters playing important roles in endogenous substances and xenobiotics transport out of the liver. Children, elderly, gender and physio-pathological conditions could influence their expression and result in changes in drug disposition.

  16. Phenotypic and genotypic analysis of multidrug-resistant tuberculosis in Ethiopia.

    NARCIS (Netherlands)

    Agonafir, M.; Lemma, E.; Wolde-Meskel, D.; Goshu, S.; Santhanam, A.; Girmachew, F.; Demissie, D.; Getahun, M.; Gebeyehu, M.; Soolingen, D. van

    2010-01-01

    SETTING: National Tuberculosis Reference Laboratory, Addis Ababa, Ethiopia. OBJECTIVES: To determine the drug susceptibility pattern of Mycobacterium tuberculosis isolates and to genetically characterise multidrug-resistant tuberculosis (MDR-TB) isolates. DESIGN: A total of 107 M. tuberculosis isola

  17. Risk factors for nosocomial bloodstream infection caused by multidrug resistant gram-negative bacilli in pediatrics

    Directory of Open Access Journals (Sweden)

    Mariana V. Arnoni

    2007-04-01

    Full Text Available The aim of this study was to identify the risk factors for nosocomial bloodstream infections by multidrug resistant Gram-negative bacilli. From November 2001 to December 2003, in the Pediatric Department of the Santa Casa de São Paulo, a retrospective case-control study was developed concerning patients who had nosocomial bloodstream infection caused by Gram-negative bacilli. Patients with multidrug resistant infections were designated as case patients, and control patients were those with an infection that did not meet the criteria for multidrug resistance. Previous use of central venous catheter and previous use of vancomycin plus third generation cephalosporins were associated to a higher chance of infections by multidrug resistant Gram-negative bacilli (Odds ratio - 5.8 and 5.2, respectively. Regarding sensitivity of the isolated agents, 47.8% were multidrug resistant, 54.2% were Klebsiella spp. ESBL producers and 36.4% were imipenem resistant Pseudomonas aeruginosa. The lethality rate was 36.9% in the studied cases and this rate was significantly higher in the group of patients with multidrug resistant infections (p=0.013. Risk factor identification as well as the knowledge of the susceptibility of the nosocomial infectious agents gave us the possibility to perform preventive and control strategies to reduce the costs and mortality related to these infections.

  18. Reversal of the multidrug resistance by drug combination using multifunctional liposomes

    Science.gov (United States)

    Patel, Niravkumar R.

    One of the major obstacles to the success of cancer chemotherapy is the multi-drug resistance (MDR) that results due mainly to the over-expression of drug efflux transporter pumps such as P-glycoprotein (P-gp). Highly efficacious third generation P-gp inhibitors, like tariquidar, have shown promising results against MDR. However, P-gp is also expressed in normal tissues like the blood-brain barrier, gastrointestinal tract, liver and kidney. It is therefore important to limit the exposure of P-gp inhibitors to normal tissues and increase their co-localization with anticancer agents in tumor tissues to maximize the efficacy of a P-gp inhibitor. To minimize non-specific binding and increase its delivery to tumor tissues, liposomes, self-assembling phospholipid vesicles, were chosen as a drug delivery vehicle. The liposome has been identified as a system capable of carrying molecules with diverse physicochemical properties. It can also alter the pharmacokinetic profile of loaded molecules which is a concern with both tariquidar and paclitaxel. Liposomes can easily be surface-modified rendering them cell-specific as well as organelle-specific. The main objective of present study was to develop an efficient liposomal delivery system which would deliver therapeutic molecules of interest to tumor tissues and avoid interaction with normal tissues. In this study, the co-delivery of tariquidar and paclitaxel into tumor cells to reverse the MDR using long-circulating cationic liposomes was investigated. SKOV-3TR, the resistant variant of SKOV-3 and MCF-7/ADR, the resistant variant of MCF-7 were used as model cell lines. Uniform liposomal formulations were generated with high incorporation efficiency and no apparent decrease in tariquidar potency towards P-gp. Tariquidar- and paclitaxel- co-loaded long-circulating liposomes showed significant re-sensitization of SKOV-3TR and MCF-7/ADR for paclitaxel in vitro. Further modification of these liposomes with antitumor 2C5 resulted

  19. Hospital costs of nosocomial multi-drug resistant Pseudomonas aeruginosa acquisition

    Directory of Open Access Journals (Sweden)

    Morales Eva

    2012-05-01

    Full Text Available Abstract Background We aimed to assess the hospital economic costs of nosocomial multi-drug resistant Pseudomonas aeruginosa acquisition. Methods A retrospective study of all hospital admissions between January 1, 2005, and December 31, 2006 was carried out in a 420-bed, urban, tertiary-care teaching hospital in Barcelona (Spain. All patients with a first positive clinical culture for P. aeruginosa more than 48 h after admission were included. Patient and hospitalization characteristics were collected from hospital and microbiology laboratory computerized records. According to antibiotic susceptibility, isolates were classified as non-resistant, resistant and multi-drug resistant. Cost estimation was based on a full-costing cost accounting system and on the criteria of clinical Activity-Based Costing methods. Multivariate analyses were performed using generalized linear models of log-transformed costs. Results Cost estimations were available for 402 nosocomial incident P. aeruginosa positive cultures. Their distribution by antibiotic susceptibility pattern was 37.1% non-resistant, 29.6% resistant and 33.3% multi-drug resistant. The total mean economic cost per admission of patients with multi-drug resistant P. aeruginosa strains was higher than that for non-resistant strains (15,265 vs. 4,933 Euros. In multivariate analysis, resistant and multi-drug resistant strains were independently predictive of an increased hospital total cost in compared with non-resistant strains (the incremental increase in total hospital cost was more than 1.37-fold and 1.77-fold that for non-resistant strains, respectively. Conclusions P. aeruginosa multi-drug resistance independently predicted higher hospital costs with a more than 70% increase per admission compared with non-resistant strains. Prevention of the nosocomial emergence and spread of antimicrobial resistant microorganisms is essential to limit the strong economic impact.

  20. 乳腺癌实施化疗后癌干细胞同P-糖蛋白及耐药蛋白在残存癌组织中表达的相关性%Breast cancer stem cells after chemotherapy with P - glycoprotein and resistant protein expression of correlation in the residual carcinoma tissue

    Institute of Scientific and Technical Information of China (English)

    乔婉晴; 涂巍

    2014-01-01

    目的:研究乳腺癌实施化疗后癌干细胞、P-糖蛋白及耐药蛋白在残存癌组织中的表达情况。方法将本院2012年5月至2013年5月收治的53例乳腺癌患者作为研究对象,比较化疗前后癌组织中癌干细胞、P-糖蛋白及耐药蛋白表达情况。结果患者化疗后,残留癌细胞中的癌干细胞含量上升且形成的微球体直径增加,与化疗前相比差异具有显著性(t=6.3615,191.3086;P=0.0000);患者化疗后,残留癌细胞中癌干细胞内谷胱甘肽转移酶π、拓补异构酶Ⅱ的阳性表达率上升,与化疗前相比差异具有显著性(χ2=3.9775,4.4002;P=0.0461,0.0359);患者化疗后,残留癌组织中P-糖蛋白表达水平上升,而耐药蛋白表达水平上升极其明显;与化疗前相比差异极其显著(t=6.5045,11.2765;P=0.0000)。结论乳腺癌患者在化疗后,残存癌组织中的癌干细胞含量上升、P-糖蛋白及耐药蛋白的阳性表达率上升,产生一定的耐药性。%ObjectiveTo study the breast cancer stem cells after chemotherapy, P-glycoprotein and resistant protein expression in the residual carcinoma tissue.MethodsFrom May 2012 to May 2013 were 53 cases of breast cancer patients as the research object, compared before and after chemotherapy cancer stem cells in cancer tissue, P-glycoprotein and resistant protein expression.ResultsThe patients after chemotherapy, residual carcinoma cells in cancer stem cells content increased and the formation of the microsphere diameter increase, signiifcant difference compared with before treatment (t=6.3615, 191.3086;P=6.3615). Cancer stem cells in patients after chemotherapy, residual cancer cells within the glutathione transferase PI, the topology isomerase II the positive expression rate of rise, compared with before treatment with statistical signiifcance (χ2=3.9775, 3.9775;P=0.0461, 0.0359); after chemotherapy, patients with residual P-glycoprotein

  1. Modulation of multidrug resistance by flavonoids. Inhibitors of glutathione conjugation and MRP-mediated transport

    OpenAIRE

    Zanden, van, J.J.

    2005-01-01

    In this thesis, the use of flavonoids for inhibition of two important players in the glutathione related biotransformation system involved in multidrug resistance was investigated using several in vitro model systems. The enzymes of interest included the phase II glutathione S-transferase enzyme GSTP1-1, able to detoxify anticancer agents through conjugation with glutathione and the two multidrug resistance proteins MRP1 and MRP2 involved in glutathione mediated cellular efflux of, amongst ot...

  2. Influence of efflux pump inhibitors on the multidrug resistance of Helicobacter pylori

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    AIM:To evaluate the effect of efflux pump inhibitors (EPIs) on multidrug resistance of Helicobacter pylori (H. pylori).METHODS: H. pylori strains were isolated and cultured on Brucella agar plates with 10% sheep's blood. The multidrug resistant (MDR) H. pylori were obtained with the inducer chloramphenicol by repeated doubling of the concentration until no colony was seen, then the susceptibilities of the MDR strains and their parents to 9 antibiotics were assessed with agar dilution tests. The present stud...

  3. Prevalence of Multidrug Resistant Mycobacterium tuberculosis by Mycobacteria growth

    Directory of Open Access Journals (Sweden)

    Livani S

    2012-01-01

    Full Text Available Background and objectives: Identification and monitoring ofmultidrugresistant Mycobacterium tuberculosis strains (MDR ishighlighted by the high risk of their spreading in different areas.Prevalence of these strains was evaluated in Golestan province innortheast of Iran.Material and Methods: Drug susceptibility testing to Isoniazid andrifampin was carried out for 148 clinical samples that had grown inMycobacteria growth indicator tube (MGIT system, according to themanufacturer's instructions (Becton-Dickinson, USA. The associationof drug resistance frequency with demographic characteristics andgrowth time were investigated. The appropriate statistical tests, X2 andstudent Ttest were performed for comparison of these variants. A pvalue>0.05 was considered significant in all cases.Results: The turnaround time required for growth of Mycobacteriumtuberculosis in MGIT system was between 2 to 55 days (mean16.3±10.4 days. Of all samples studied, 17.6% and 3.4% wereresistant to Isoniazid and rifampin, respectively, and 3.4% (5 sampleswere MDR (CI 95%; 1- 6%. The turnaround time required fordetermining MDR cases was 9.6 days. No statistically significantassociation was found between the resistance to the drugs and none ofthe factors including sex, age, type of clinical sample, and positivity ofthe smear.Conclusion: The prevalence of MDR in the studied region wasdetermined to be 3.4% which is similar to the country-wideevaluations. The turnaround time for Mycobacterium growth and antidrug susceptibility result can be shortened by MGIT method.Key words: Mycobacterium tuberculosis, Mycobacterium GrowthIndicator Tube, Multidrug Resistant

  4. [Fosfomycin--its significance for treatment of diseases due to multidrug-resistant bacteria].

    Science.gov (United States)

    Stock, Ingo

    2015-01-01

    Fosfomycin is a bactericidal phosphonic acid derivative, which engages by inhibiting pyruvyltransferase at an early stage in the peptidoglycan synthesis. It shows a broad spectrum of activity that includes many multidrug-resistant gram-negative and gram-positive bacteria. Fosfomycin is active against most strains of Pseudomonas aeruginosa and several multidrug-resistant Enterobacteriaceae, e.g., Escherichia coli strains expressing extended spectrum beta-lactamases (ESBL) and Klebsiella pneumoniae strains with decreased susceptibilities to carbapenems. Most methicillin-resistant Staphylococcus aureus (MRSA) strains as well as enterococci with and without vancomycin resistance are also sensitive to fosfomycin. During the last decade, a variety of studies showed that fosfomycin is not only suitable for treating uncomplicated urinary tract diseases, but also for the treatment of many other diseases caused by bacterial pathogens with and without multidrug resistance. However, large controlled studies demonstrating the efficacy of the drug to treat diseases caused by multidrug-resistant bacteria are still missing. Considering the low number of antibacterial agents with good activity against multidrug-resistant bacteria, fosfomycin should be evaluated as an important antibiotic for the treatment of several severe illnesses due to these pathogens. However, because some multidrug-resistant bacteria are also resistant to fosfomycin, this agent should only be applied if the pathogen is sensitive to this drug. In addition, because rapid development of resistance cannot be excluded if fosfomycin will be applied alone, this drug should only be given in combination with other effective drugs for the treatment of serious systemic diseases due to multidrug-resistant bacterial pathogens.

  5. Machine learning-, rule- and pharmacophore-based classification on the inhibition of P-glycoprotein and NorA.

    Science.gov (United States)

    Ngo, T-D; Tran, T-D; Le, M-T; Thai, K-M

    2016-09-01

    The efflux pumps P-glycoprotein (P-gp) in humans and NorA in Staphylococcus aureus are of great interest for medicinal chemists because of their important roles in multidrug resistance (MDR). The high polyspecificity as well as the unavailability of high-resolution X-ray crystal structures of these transmembrane proteins lead us to combining ligand-based approaches, which in the case of this study were machine learning, perceptual mapping and pharmacophore modelling. For P-gp inhibitory activity, individual models were developed using different machine learning algorithms and subsequently combined into an ensemble model which showed a good discrimination between inhibitors and noninhibitors (acctrain-diverse = 84%; accinternal-test = 92% and accexternal-test = 100%). For ligand promiscuity between P-gp and NorA, perceptual maps and pharmacophore models were generated for the detection of rules and features. Based on these in silico tools, hit compounds for reversing MDR were discovered from the in-house and DrugBank databases through virtual screening in an attempt to restore drug sensitivity in cancer cells and bacteria.

  6. Computational predictive models for P-glycoprotein inhibition of in-house chalcone derivatives and drug-bank compounds.

    Science.gov (United States)

    Ngo, Trieu-Du; Tran, Thanh-Dao; Le, Minh-Tri; Thai, Khac-Minh

    2016-11-01

    The human P-glycoprotein (P-gp) efflux pump is of great interest for medicinal chemists because of its important role in multidrug resistance (MDR). Because of the high polyspecificity as well as the unavailability of high-resolution X-ray crystal structures of this transmembrane protein, ligand-based, and structure-based approaches which were machine learning, homology modeling, and molecular docking were combined for this study. In ligand-based approach, individual two-dimensional quantitative structure-activity relationship models were developed using different machine learning algorithms and subsequently combined into the Ensemble model which showed good performance on both the diverse training set and the validation sets. The applicability domain and the prediction quality of the developed models were also judged using the state-of-the-art methods and tools. In our structure-based approach, the P-gp structure and its binding region were predicted for a docking study to determine possible interactions between the ligands and the receptor. Based on these in silico tools, hit compounds for reversing MDR were discovered from the in-house and DrugBank databases through virtual screening using prediction models and molecular docking in an attempt to restore cancer cell sensitivity to cytotoxic drugs.

  7. Inhibition of P-Glycoprotein Mediated Efflux of Paclitaxel by Coumarin Derivatives in Cancer Stem Cells: An In Silico Approach.

    Science.gov (United States)

    Tripathi, Anushree; Misra, Krishna

    2016-01-01

    P-glycoprotein (P-gp) is well known to cause multidrug resistance (MDR) in cancer cells. This MDR leads to cancer recurrence which is a major obstacle in cancer treatment. High P-gp expression has been observed in the population of cancer stem cells (CSCs) having self-renewal potential. Early detection and inhibition of these CSCs is directly beneficial to cancer treatment. In this study coumarin derivatives are used to inhibit efflux process and thereby enhance bioavailability of various drugs like paclitaxel (PTX). This drug is most commonly used for the treatment of cancers of breast, ovary, head and neck. Coumarin derivatives can be used to reduce the growth of breast cancer stem cells through P-gp mediated efflux inhibition and paclitaxel bioavailability enhancement. With the use of computational approaches including molecular docking simulation and pharmacophore study, few coumarin derivatives have been found to be more potential inhibitors of P-gp mediated efflux. Based on high affinity inhibitors, new coumarin derivatives have been designed and docked at active site cavity of P-gps. Some newly designed coumarin derivatives were found to be more potent due to their higher binding affinity towards target protein. The finding that newly designed coumarins can be exploited for inhibition of P-gp mediated efflux in order to enhance paclitaxel bioavailability and can inhibit breast cancer stem cell growth is significant for designing potent anticancer drugs.

  8. In silico structure-based screening of versatile P-glycoprotein inhibitors using polynomial empirical scoring functions.

    Science.gov (United States)

    Shityakov, Sergey; Förster, Carola

    2014-01-01

    P-glycoprotein (P-gp) is an ATP (adenosine triphosphate)-binding cassette transporter that causes multidrug resistance of various chemotherapeutic substances by active efflux from mammalian cells. P-gp plays a pivotal role in limiting drug absorption and distribution in different organs, including the intestines and brain. Thus, the prediction of P-gp-drug interactions is of vital importance in assessing drug pharmacokinetic and pharmacodynamic properties. To find the strongest P-gp blockers, we performed an in silico structure-based screening of P-gp inhibitor library (1,300 molecules) by the gradient optimization method, using polynomial empirical scoring (POLSCORE) functions. We report a strong correlation (r (2)=0.80, F=16.27, n=6, P<0.0157) of inhibition constants (Kiexp or pKiexp; experimental Ki or negative decimal logarithm of Kiexp) converted from experimental IC50 (half maximal inhibitory concentration) values with POLSCORE-predicted constants (KiPOLSCORE or pKiPOLSCORE), using a linear regression fitting technique. The hydrophobic interactions between P-gp and selected drug substances were detected as the main forces responsible for the inhibition effect. The results showed that this scoring technique might be useful in the virtual screening and filtering of databases of drug-like compounds at the early stage of drug development processes.

  9. Identification and characterization of functionally important elements in the multidrug resistance protein 1 COOH-terminal region.

    Science.gov (United States)

    Westlake, Christopher J; Payen, Lea; Gao, Mian; Cole, Susan P C; Deeley, Roger G

    2004-12-17

    The ATP binding cassette (ABC) transporter, multidrug resistance protein 1 (MRP1/ABCC1), transports a broad spectrum of conjugated and unconjugated compounds, including natural product chemotherapeutic agents. In this study, we have investigated the importance of the COOH-terminal region of MRP1 for transport activity and basolateral plasma membrane trafficking. The COOH-terminal regions of some ABCC proteins have been implicated in protein trafficking, but the function of this region of MRP1 has not been defined. In contrast to results obtained with other ABCC proteins, we found that the COOH-proximal 30 amino acids of MRP1 can be removed without affecting trafficking to basolateral membranes. However, the truncated protein is inactive. Furthermore, removal of as few as 4 COOH-terminal amino acids profoundly decreases transport activity. Although amino acid sequence conservation of the COOH-terminal regions of ABC proteins is low, secondary structure predictions indicate that they consist of a broadly conserved helix-sheet-sheet-helix-helix structure. Consistent with a conservation of secondary and tertiary structure, MRP1 hybrids containing the COOH-terminal regions of either the homologous MRP2 or the distantly related P-glycoprotein were fully active and trafficked normally. Using mutated proteins, we have identified structural elements containing five conserved hydrophobic amino acids that are required for activity. We show that these are important for binding and hydrolysis of ATP by nucleotide binding domain 2. Based on crystal structures of several ABC proteins, we suggest that the conserved amino acids may stabilize a helical bundle formed by the COOH-terminal three helices and may contribute to interactions between the COOH-terminal region and the protein's two nucleotide binding domains.

  10. The multidrug resistance 1 gene Abcb1 in brain and placenta: comparative analysis in human and guinea pig.

    Science.gov (United States)

    Pappas, Jane J; Petropoulos, Sophie; Suderman, Matthew; Iqbal, Majid; Moisiadis, Vasilis; Turecki, Gustavo; Matthews, Stephen G; Szyf, Moshe

    2014-01-01

    The Multidrug Resistance 1 (MDR1; alternatively ABCB1) gene product P-glycoprotein (P-gp), an ATP binding cassette transporter, extrudes multiple endogenous and exogenous substrates from the cell, playing an important role in normal physiology and xenobiotic distribution and bioavailability. To date, the predominant animal models used to investigate the role of P-gp have been the mouse and rat, which have two distinct genes, Abcb1a and Abcb1b. In contrast, the human has a single gene, ABCB1, for which only a single isoform has been validated. We and others have previously shown important differences between Abcb1a and Abcb1b, limiting the extrapolation from rodent findings to the human. Since the guinea pig has a relatively long gestation, hemomonochorial placentation and neuroanatomically mature offspring, it is more similar to the human, and may provide a more comparable model for investigating the regulation of P-gp in the brain and placenta, however, to date, the Abcb1 gene in the guinea pig remains to be characterized. The placenta and fetal brain are barrier sites that express P-gp and that play a critical role of protection of the fetus and the fetal brain from maternally administered drugs and other xenobiotics. Using RNA sequencing (RNA-seq), reverse transcription-polymerase chain reaction (RT-PCR) and quantitative PCR (QPCR) to sequence the expressed isoforms of guinea pig Abcb1, we demonstrate that like the human, the guinea pig genome contains one gene for Abcb1 but that it is expressed as at least three different isoforms via alternative splicing and alternate exon usage. Further, we demonstrate that these isoforms are more closely related to human than to rat or mouse isoforms. This striking, overall similarity and evolutionary relatedness between guinea pig Abcb1 and human ABCB1 indicate that the guinea pig represents a relevant animal model for investigating the function and regulation of P-gp in the placenta and brain.

  11. IMPROVING P-gp EXPRESSION IN HUMAN MONONUCLEAR CELLS IN VITRO TRANSFECTED BY MULTIDRUG RESISTANCE-1 mRNA

    Institute of Scientific and Technical Information of China (English)

    Yang Xiang; Lei Li; Fang Tian; Xiu-yu Yang

    2005-01-01

    Objective To evaluate the expression and function activity of P-glycoprotein (P-gp) in human mononuclear cells (MNCs) in vitro transfected by multidrug resistance-1 (MDR1) mRNA.Methods Two MDR1 cDNA vectors, pT7TS_MDR1 and pGEM5Zf(+)_MDR1, were constructed and transcripted in vitro. Vector pGEM5Zf(+)_MDR1 only contained the coding region ofmdrl cDNA, and pT7TS_MDR1 also included Xeponus β-globin 5' and 3' untranslated region. MNCs were prepared from peripheral blood of parvicellular lung cancer patient. The two human mdrl mRNAs were then transferred into human MNCs in vitro by DOTAP. And the expression efficiency and pump functon of P-gp were measured with flow cytometry.Results Expression of P-gp significantly elevated in both transferred cells compared with untransferred cells (P< 0.01).And pT7TS_MDR1 showed higher capability in elevating the expression of P-gp than pGEM5Zf(+)_MDR1 (P < 0.01). The P-gp function was elevated in both pT7TS_MDR1 and pGEM5Zf(+)_MDR1 groups. The survival ratio of MNCs in erythrocyte-lysis-solution (ELS, 86.07%) and lymphocyte-isolation-solution (LIS, 83.67%) had no significant difference.The CD34+ cells content of the MNCs used for transfection was 2.65% and 1.01% in ELS and LIS group, respectively (P <0.01).Conclusions It is a feasible approach to improve P-gp expression in human MNCs by transfection of MDR-1 mRNA.And the ELS may be more suitable for purifing MNCs for mRNA transfection than LIS.

  12. The emergence and outbreak of multidrug-resistant typhoid fever in China.

    Science.gov (United States)

    Yan, Meiying; Li, Xinlan; Liao, Qiaohong; Li, Fang; Zhang, Jing; Kan, Biao

    2016-06-22

    Typhoid fever remains a severe public health problem in developing countries. The emergence of resistant typhoid, particularly multidrug-resistant typhoid infections, highlights the necessity of monitoring the resistance characteristics of this invasive pathogen. In this study, we report a typhoid fever outbreak caused by multidrug-resistant Salmonella enterica serovar Typhi strains with an ACSSxtT pattern. Resistance genes conferring these phenotypes were harbored by a large conjugative plasmid, which increases the threat of Salmonella Typhi and thus requires close surveillance for dissemination of strains containing such genes.

  13. Localized Down-regulation of P-glycoprotein by Focused Ultrasound and Microbubbles induced Blood-Brain Barrier Disruption in Rat Brain

    Science.gov (United States)

    Cho, HongSeok; Lee, Hwa-Youn; Han, Mun; Choi, Jong-ryul; Ahn, Sanghyun; Lee, Taekwan; Chang, Yongmin; Park, Juyoung

    2016-01-01

    Multi-drug resistant efflux transporters found in Blood-Brain Barrier (BBB) acts as a functional barrier, by pumping out most of the drugs into the blood. Previous studies showed focused ultrasound (FUS) induced microbubble oscillation can disrupt the BBB by loosening the tight junctions in the brain endothelial cells; however, no study was performed to investigate its impact on the functional barrier of the BBB. In this study, the BBB in rat brains were disrupted using the MRI guided FUS and microbubbles. The immunofluorescence study evaluated the expression of the P-glycoprotein (P-gp), the most dominant multi-drug resistant protein found in the BBB. Intensity of the P-gp expression at the BBB disruption (BBBD) regions was significantly reduced (63.2 ± 18.4%) compared to the control area. The magnitude of the BBBD and the level of the P-gp down-regulation were significantly correlated. Both the immunofluorescence and histologic analysis at the BBBD regions revealed no apparent damage in the brain endothelial cells. The results demonstrate that the FUS and microbubbles can induce a localized down-regulation of P-gp expression in rat brain. The study suggests a clinically translation of this method to treat neural diseases through targeted delivery of the wide ranges of brain disorder related drugs. PMID:27510760

  14. Localized Down-regulation of P-glycoprotein by Focused Ultrasound and Microbubbles induced Blood-Brain Barrier Disruption in Rat Brain

    Science.gov (United States)

    Cho, Hongseok; Lee, Hwa-Youn; Han, Mun; Choi, Jong-Ryul; Ahn, Sanghyun; Lee, Taekwan; Chang, Yongmin; Park, Juyoung

    2016-08-01

    Multi-drug resistant efflux transporters found in Blood-Brain Barrier (BBB) acts as a functional barrier, by pumping out most of the drugs into the blood. Previous studies showed focused ultrasound (FUS) induced microbubble oscillation can disrupt the BBB by loosening the tight junctions in the brain endothelial cells; however, no study was performed to investigate its impact on the functional barrier of the BBB. In this study, the BBB in rat brains were disrupted using the MRI guided FUS and microbubbles. The immunofluorescence study evaluated the expression of the P-glycoprotein (P-gp), the most dominant multi-drug resistant protein found in the BBB. Intensity of the P-gp expression at the BBB disruption (BBBD) regions was significantly reduced (63.2 ± 18.4%) compared to the control area. The magnitude of the BBBD and the level of the P-gp down-regulation were significantly correlated. Both the immunofluorescence and histologic analysis at the BBBD regions revealed no apparent damage in the brain endothelial cells. The results demonstrate that the FUS and microbubbles can induce a localized down-regulation of P-gp expression in rat brain. The study suggests a clinically translation of this method to treat neural diseases through targeted delivery of the wide ranges of brain disorder related drugs.

  15. Tetracyclines for multidrug-resistant Acinetobacter baumannii infections.

    Science.gov (United States)

    Falagas, Matthew E; Vardakas, Konstantinos Z; Kapaskelis, Anastasios; Triarides, Nikolaos A; Roussos, Nikolaos S

    2015-05-01

    Multidrug-resistant (MDR) Acinetobacter baumannii infections have emerged as a serious threat worldwide. As novel agents have yet to be developed, understanding the effectiveness and safety of older antibiotics has become a priority. The purpose of this systematic review was to summarise the available clinical evidence on the use of tetracyclines for the treatment of A. baumannii infections. Ten retrospective studies regarding doxycycline and minocycline for the treatment of 185 A. baumannii infections (of which 65.4% were respiratory infections and 13% were bloodstream infections) in 156 patients were available. In most cases (86.4%), tetracyclines were administered in combination with another agent. The usual dosage of doxycycline or minocycline was 100mg intravenous or per os twice daily (usually with a 200mg loading dose for minocycline). Clinical success was achieved in 120 (76.9%) of 156 patients; in 87 (71.9%) of 121 respiratory infections and in 21 (87.5%) of 24 bloodstream infections. Twenty-two deaths occurred in 100 recorded cases. Microbiological eradication was attained in 72 (71.3%) of 101 available cases and documented microbiological eradication was reached in 59 (66.3%) of 89 available cases. Adverse events were noted in only 1 of 88 cases. Overall, although tetracycline-containing regimens showed encouraging results, more data from larger comparative trials are required to establish a role for these antibiotics in the treatment of MDR A. baumannii infections.

  16. Multidrug resistant citrobacter: an unusual cause of liver abscess.

    Science.gov (United States)

    Kumar, Prabhat; Ghosh, Soumik; Rath, Deepak; Gadpayle, A K

    2013-04-22

    Liver abscesses are infectious, space occupying lesions in the liver, the two most common abscesses being pyogenic and amoebic. A pyogenic liver abscess (PLA) is a rare condition with a reported incidence of 20 per 100 000 hospital admissions in the western population. The right lobe of the liver is the most common site in both types of liver abscess. Clinical presentation is elusive with complaints of fever, right upper quadrant pain in the abdomen and hepatomegaly with or without jaundice. The aetiology of PLA has changed in the past few decades and may be of biliary, portal, arterial or traumatic origin, but many cases are still cryptogenic. The most common organisms causing PLA are Gram-negative aerobes, especially Escherichia coli and Klebsiella pneumoniae. Studies have shown a high degree of antimicrobial susceptibility of isolated organism resulting in an overall lower mortality in PLA. Here, we present a case of PLA caused by multidrug-resistant Citrobacter freundii, which is an unusual organism to be isolated.

  17. Intracellular pH and the Control of Multidrug Resistance

    Science.gov (United States)

    Simon, Sanford; Roy, Deborshi; Schindler, Melvin

    1994-02-01

    Many anticancer drugs are classified as either weak bases or molecules whose binding to cellular structures is pH dependent. Accumulation of these drugs within tumor cells should be affected by transmembrane pH gradients. Indeed, development of multidrug resistance (MDR) in tumor cells has been correlated with an alkaline shift of cytosolic pH. To examine the role of pH in drug partitioning, the distribution of two drugs, doxorubicin and daunomycin, was monitored in fibroblasts and myeloma cells. In both cell types the drugs rapidly accumulated within the cells. The highest concentrations were measured in the most acidic compartments-e.g., lysosomes. Modifying the cellular pH in drug-sensitive cells to mimic reported shifts in MDR caused an immediate change in the cellular drug concentration. Drug accumulation was enhanced by acidic shifts and reversed by alkaline shifts. All of these effects were rapid and reversible. These results demonstrate that the alkaline shift observed in MDR is sufficient to prevent the accumulation of chemotherapeutic drugs independent of active drug efflux.

  18. Dominance of multidrug resistant CC271 clones in macrolide-resistant streptococcus pneumoniae in Arizona

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    Bowers Jolene R

    2012-01-01

    Full Text Available Abstract Background Rates of resistance to macrolide antibiotics in Streptococcus pneumoniae are rising around the world due to the spread of mobile genetic elements harboring mef(E and erm(B genes and post-vaccine clonal expansion of strains that carry them. Results Characterization of 592 clinical isolates collected in Arizona over a 10 year period shows 23.6% are macrolide resistant. The largest portion of the macrolide-resistant population, 52%, is dual mef(E/erm(B-positive. All dual-positive isolates are multidrug-resistant clonal lineages of Taiwan19F-14, mostly multilocus sequence type 320, carrying the recently described transposon Tn2010. The remainder of the macrolide resistant S. pneumoniae collection includes 31% mef(E-positive, and 9% erm(B-positive strains. Conclusions The dual-positive, multidrug-resistant S. pneumoniae clones have likely expanded by switching to non-vaccine serotypes after the heptavalent pneumococcal conjugate vaccine release, and their success limits therapy options. This upsurge could have a considerable clinical impact in Arizona.

  19. Diverse and abundant multi-drug resistant E. coli in Matang mangrove estuaries, Malaysia.

    Science.gov (United States)

    Ghaderpour, Aziz; Ho, Wing Sze; Chew, Li-Lee; Bong, Chui Wei; Chong, Ving Ching; Thong, Kwai-Lin; Chai, Lay Ching

    2015-01-01

    E.coli, an important vector distributing antimicrobial resistance in the environment, was found to be multi-drug resistant, abundant, and genetically diverse in the Matang mangrove estuaries, Malaysia. One-third (34%) of the estuarine E. coli was multi-drug resistant. The highest antibiotic resistance prevalence was observed for aminoglycosides (83%) and beta-lactams (37%). Phylogenetic groups A and B1, being the most predominant E. coli, demonstrated the highest antibiotic resistant level and prevalence of integrons (integron I, 21%; integron II, 3%). Detection of phylogenetic group B23 downstream of fishing villages indicates human fecal contamination as a source of E. coli pollution. Enteroaggregative E. coli (1%) were also detected immediately downstream of the fishing village. The results indicated multi-drug resistance among E. coli circulating in Matang estuaries, which could be reflective of anthropogenic activities and aggravated by bacterial and antibiotic discharges from village lack of a sewerage system, aquaculture farms and upstream animal husbandry.

  20. [Significance of efflux pumps in multidrug resistance of Gram-negative bacteria].

    Science.gov (United States)

    Wiercińska, Olga; Chojecka, Agnieszka; Kanclerski, Krzysztof; Rőhm-Rodowald, Ewa; Jakimiak, Bożenna

    2015-01-01

    The phenomenon of multidrug. resistance of bacteria is a serious problem of modern medicine. This resistance largely is a consequence of abuse and improper use of antibacterial substances, especially antibiotics and chemotherapeutics in hospital settings. Multidrug resistance is caused by a number of interacting mechanisms of resistance. Recent studies have indicated that efflux pumps and systems of efflux pumps are an important determinant of this phenomenon. Contribute to this particular RND efflux systems of Gram-negative bacteria, which possess a wide range of substrates such as antibiotics, dyes, detergents, toxins and active substances of disinfectants and antiseptics. These transporters are usually encoded on bacterial chromosomes. Genes encoding efflux pumps' proteins may also be carried on plasmids and other mobile genetic elements. Such pumps are usually specific to a small group of substrates, but as an additional mechanism of resistance may contribute to the multidrug resistance.

  1. Modulation of breast cancer resistance protein mediated atypical multidrug resistance using RNA interference delivered by adenovirus

    Institute of Scientific and Technical Information of China (English)

    LI Wen-tong; ZHOU Geng-yin; WANG Chun-ling; GUO Cheng-hao; SONG Xian-rang; CHI Wei-ling

    2005-01-01

    @@ Clinical multidrug resistance (MDR) of malignancies to many antineoplastic agents is the major obstacle in the successful treatment of cancer. The emergence of breast cancer resistance protein (BCRP), a member of the adenosine triphosphate (ATP) binding cassette (ABC) transporter family, has necessitated the development of antagonists. To overcome the BCRP-mediated atypical MDR, RNA interference (RNAi) delivered by adenovirus targeting BCRP mRNA was used to inhibit the atypical MDR expression by infecting MCF-7/MX100 cell lines with constructed RNAi adenovirus.

  2. Emergence of fluoroquinolones-resistant strains of Salmonella typhi: Watch on multidrug-resistant isolates

    Directory of Open Access Journals (Sweden)

    Subhash C Arya

    2010-05-01

    Full Text Available Subhash C Arya, Nirmala Agarwal, Shekhar Agarwal, Dolly WadhwaSant Parmanand Hospital, Delhi, IndiaEmergence of multidrug-resistant Salmonella typhi has been responsible for clinical challenges for clinicians. Recently, frequent isolation and dissemination of fluoroquinolones-resistant strains of S. enterica in Surabaya, Indonesia was in the news. Subsequently, Yangai and colleagues1 recommended regular communications between laboratory professionals and clinicians. Collaboration between laboratory personnel and clinicians would be essential to offer a rational empiric antibiotic recipe while awaiting antibiotic susceptibility test results (AST for any patient.

  3. Multifunctional polyamidoamine-modified selenium nanoparticles dual-delivering siRNA and cisplatin to A549/DDP cells for reversal multidrug resistance.

    Science.gov (United States)

    Zheng, Wenjing; Cao, Chengwen; Liu, Yanan; Yu, Qianqian; Zheng, Chuping; Sun, Dongdong; Ren, Xiaofan; Liu, Jie

    2015-01-01

    Multidrug resistance (MDR) is a major barrier against effective cancer treatment. Dual-delivering a therapeutic small interfering RNA (siRNA) and chemotherapeutic agents has been developed to reverse drug resistance in tumor cells. In this study, amine-terminated generation 5 polyamidoamine (PAMAM) dendrimers (G5.NH2)-modified selenium nanoparticles (G5@Se NP) were synthesized for the systemic dual-delivery of mdr1 siRNA and cisplatin (cis-diamminedichloroplatinum-(II), DDP), which was demonstrated to enhance siRNA loading, releasing efficiency and gene-silencing efficacy. When the mdr1 siRNA was conjugated with G5@Se NP via electrostatic interaction, a significant down-regulation of P-glycoprotein and multidrug resistance-associated protein expression was observed; G5@Se-DDP-siRNA arrested A549/DDP cells at G1 phase and led to enhanced cytotoxicity in A549/DDP cells through induction of apoptosis involving the AKT and ERK signaling pathways. Interestingly, G5@Se-DDP NP were much less reactive than DDP in the reactions with both MT and GSH, indicating that loading of DDP in a nano-delivery system could effectively prevent cell detoxification. Furthermore, animal studies demonstrated that the new delivery system of G5@Se-DDP-siRNA significantly enhanced the anti-tumor effect on tumor-bearing nude mice, with no appreciable abnormality in the major organs. These results suggest that G5@Se NP could be a potential platform to combine chemotherapy and gene therapy technology in the treatment of human disease.

  4. Draft genome sequence of a multidrug-resistant Chryseobacterium indologenes isolate from Malaysia

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    Choo Yee Yu

    2016-03-01

    Full Text Available Chryseobacterium indologenes is an emerging pathogen which poses a threat in clinical healthcare setting due to its multidrug-resistant phenotype and its common association with nosocomial infections. Here, we report the draft genome of a multidrug-resistant C. indologenes CI_885 isolated in 2014 from Malaysia. The 908,704-kb genome harbors a repertoire of putative antibiotic resistance determinants which may elucidate the molecular basis and underlying mechanisms of its resistant to various classes of antibiotics. The genome sequence has been deposited in DDBJ/EMBL/GenBank under the accession number LJOD00000000.

  5. Multidrug resistant Acinetobacter baumannii in veterinary medicine--emergence of an underestimated pathogen?

    Science.gov (United States)

    Müller, Stefanie; Janssen, Traute; Wieler, Lothar H

    2014-01-01

    The proportion of multidrug resistant bacteria causing infections in animals has continuously been increasing. While the relevance of ESBL (extended spectrum beta-lactamase)-producing Enterobacteriaceae spp. and MRSA (methicillin resistant Staphylococcus aureus) is unquestionable, knowledge about multidrug resistant Acinetobacter baumannii in veterinary medicine is scarce. This is a worrisome situation, as A. baumannii are isolated from veterinary clinical specimens with rising frequency. The remarkable ability of A. baumannii to develop multidrug resistance and the high risk of transmission are known in human medicine for years. Despite this, data regarding A. baumannii isolates of animal origin are missing. Due to the changing role of companion animals with closer contact between animal and owner, veterinary intensive care medicine is steadily developing. It can be assumed that the number of "high risk" patients with an enhanced risk for hospital acquired infections will be rising simultaneously. Thus, development and spread of multidrug resistant pathogens is envisioned to rise. It is possible, that A. baumannii will evolve into a veterinary nosocomial pathogen similar to ESBL-producing Enterobacteriaceae and MRSA. The lack of attention paid to A. baumannii in veterinary medicine is even more worrying, as first reports indicate a transmission between humans and animals. Essential questions regarding the role of livestock, especially as a potential source of multidrug resistant isolates, remain unanswered. This review summarizes the current knowledge on A. baumannii in veterinary medicine for the first time. It underlines the utmost significance of further investigations of A. baumannii animal isolates, particularly concerning epidemiology and resistance mechanisms.

  6. 捻转血矛线虫伊维菌素耐药株P-糖蛋白基因多态性的PCR-RFLP分析%Polymorphism analysis of P-glycoprotein gene in Haemonchus contortus of ivermectin resistance strains by PCR-RFLP

    Institute of Scientific and Technical Information of China (English)

    刘鑫远; 杨晓野; 王瑞; 杨莲茹; 罗晓平; 阿拉腾宝力格; 贺志雄

    2012-01-01

    To study the differences of P-glycoprotein gene between ivermectin-resistant(HY) and sus- ceptible strains(HM) of Haemonchus contortus and further clarify the relationship between P-glycoprotein gene and ivermectin resistance in future, the polymorphism of P-glycoprotein gene from ivermectin-resis- rant strain of H. contortus in sheep was analyzed by PCR-restriction fragment length polymorphism. The result showed that the PCR products of HM group were resistive to the restriction enzyme Kpn I , whileHY group were vulnerable to the enzyme. The statistics data showed that 10 nematodes of ivermectin-sus- ceptible strains were all homozygote(BB);in 20 nematodes of ivermectin-resistance strain, there were 6 ivermectin-resistant homozygotes (AA, 30 %), 13 heterozygotes (AB, 65% ) and only 1 ivermectin-suscepti- ble homozygote(BB, 5 %). The heterozygote(AB) was the most dominant genotype, followed by ivermectin- resistant homozygotes(AA),and ivermectin-susceptible homozygote(BB) was the least. The resistance al- lele A was the most dominant gene,and took 62.5%,while allele B was only 37.5% of the samples. The homologous analysis revealed that the P-glycoprotein gene of ivermectin resistance(hcpgp-1) shared low homology(80. 2% to 89. 3%) with the susceptible strains. Besides, mutant sites on the hcpgp-1 gene of ivermectin-resistant strains were also found. This paper could provide a reference for studying the effects of P-glycoprotein gene in ivermectin resistance. And it also could supply basic information for the mechanism study of resistance to common anthelmintics of H. contortus.%为了解P-糖蛋白基因在捻转血矛线虫伊维菌素耐药株和敏感株间的差异,进一步弄清该基因与伊维菌素耐药性产生的关系,用PCR-RFLP方法分析了捻转血矛线虫伊维菌素耐药株P-糖蛋白基因hcpgp-1的多态性,并对所得序列进行测序。结果表明:捻转血矛线虫伊维菌素敏感

  7. Ivermectin induces P-glycoprotein expression and function through mRNA stabilization in murine hepatocyte cell line.

    Science.gov (United States)

    Ménez, Cécile; Mselli-Lakhal, Laïla; Foucaud-Vignault, Magali; Balaguer, Patrick; Alvinerie, Michel; Lespine, Anne

    2012-01-15

    Ivermectin is widely used in human and veterinary medicine for the control of helminth infections. Ivermectin is known to interact with P-glycoprotein (P-gp/MDR1), being a good substrate and a potent inhibitor, however, the influence of ivermectin on the expression of the transporter has not been investigated. Expression of P-glycoprotein was investigated in cultured mouse hepatocytes acutely exposed to ivermectin. The two P-glycoprotein murine isoforms, Mdr1a and Mdr1b, mRNA levels were assessed by real-time RT-PCR. Ivermectin induced a clear time- and concentration-dependent up-regulation of Mdr1a and Mdr1b mRNA levels (as early as a 12-h exposure and up to 2.5-fold at 10μM). Moreover, ivermectin-treated cells displayed enhanced cellular efflux of the P-glycoprotein substrate calcein that was inhibited by the P-glycoprotein blocker valspodar, providing evidence that the ivermectin-induced P-glycoprotein was functional. The mechanisms underlying these effects were investigated. Ivermectin-mediated Mdr1 mRNA induction was independent of the two nuclear receptors CAR and PXR, which are known to be involved in drug transporters regulation. Moreover, by using reporter cell lines that detects specific ligand-activated transcription factors, we showed that ivermectin did not displayed CAR, PXR or AhR ligand activities. However, studies with actinomycin D revealed that the half-life of Mdr1a and Mdr1b mRNA were significantly prolonged by two-fold in ivermectin-treated cells suggesting a post-transcriptional mode of ivermectin regulation. This study demonstrates for the first time that ivermectin induces P-glycoprotein overexpression through post-transcriptional mRNA stabilization, thus offering insight into the mechanism of reduced therapeutic efficacy and development of ivermectin-resistant parasites.

  8. Absence of P-glycoprotein transport in the pharmacokinetics and toxicity of the herbicide paraquat.

    Science.gov (United States)

    Lacher, Sarah E; Gremaud, Julia N; Skagen, Kasse; Steed, Emily; Dalton, Rachel; Sugden, Kent D; Cardozo-Pelaez, Fernando; Sherwin, Catherine M T; Woodahl, Erica L

    2014-02-01

    Genetic variation in the multidrug resistance gene ABCB1, which encodes the efflux transporter P-glycoprotein (P-gp), has been associated with Parkinson disease. Our goal was to investigate P-gp transport of paraquat, a Parkinson-associated neurotoxicant. We used in vitro transport models of ATPase activity, xenobiotic-induced cytotoxicity, transepithelial permeability, and rhodamine-123 inhibition. We also measured paraquat pharmacokinetics and brain distribution in Friend leukemia virus B-type (FVB) wild-type and P-gp-deficient (mdr1a(-/-)/mdr1b(-/-)) mice following 10, 25, 50, and 100 mg/kg oral doses. In vitro data showed that: 1) paraquat failed to stimulate ATPase activity; 2) resistance to paraquat-induced cytotoxicity was unchanged in P-gp-expressing cells in the absence or presence of P-gp inhibitors GF120918 [N-(4-[2-(1,2,3,4-tetrahydro-6,7-dimethoxy-2-isoquinolinyl)ethyl]-phenyl)-9,10-dihydro-5-methoxy-9-oxo-4-acridine carboxamide] and verapamil-37.0 [95% confidence interval (CI): 33.2-41.4], 46.2 (42.5-50.2), and 34.1 µM (31.2-37.2)-respectively; 3) transepithelial permeability ratios of paraquat were the same in P-gp-expressing and nonexpressing cells (1.55 ± 0.39 and 1.39 ± 0.43, respectively); and 4) paraquat did not inhibit rhodamine-123 transport. Population pharmacokinetic modeling revealed minor differences between FVB wild-type and mdr1a(-/-)/mdr1b(-/-) mice: clearances of 0.47 [95% confidence interval (CI): 0.42-0.52] and 0.78 l/h (0.58-0.98), respectively, and volume of distributions of 1.77 (95% CI: 1.50-2.04) and 3.36 liters (2.39-4.33), respectively; however, the change in clearance was in the opposite direction of what would be expected. It is noteworthy that paraquat brain-to-plasma partitioning ratios and total brain accumulation were the same across doses between FVB wild-type and mdr1a(-/-)/mdr1b(-/-) mice. These studies indicate that paraquat is not a P-gp substrate. Therefore, the association between ABCB1 pharmacogenomics and

  9. ACTION OF NEWER DISINFECTANTS ON MULTIDRUG RESISTANT BACTERIA

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    Bipasa

    2014-03-01

    Full Text Available BACKGROUND: Current procedures for infection control in hospital environments have not been successful in curbing the rise in infections by multi-drug-resistant (MDR pathogens. Emergence of resistance to chemical disinfectants is increasing steadily and has been reported worldwide. So prevention of multidrug-resistant health care associated infections (HAI has become a priority issue and great challenge to clinicians. This requires appropriate sterilization and disinfection procedures and strict adherence to protocol in infection control policy. There is a need to evaluate the efficacy of newer disinfectants which have come into the market for better control of HAI. AIMS AND OBJECTIVES: The aim of this study was to evaluate and compare disinfection efficacy of three newer disinfectants– Novacide (didecyldimethylammonium chloride and polyhexamethylene biguanide, Silvicide a strong oxidizing agent (hydrogen peroxide and silver nitrate and Virkon, a powerful oxidizing agent (a stabilized blend of peroxygen compounds and potassium salts, pitting them against two time-honored conventional disinfectants phenol and lysol and testing them against common MDR clinical isolates, reference strains and spores. MATERIALS AND METHODS: All the disinfectants at different dilutions were tested for bactericidal efficacy by liquid suspension time-kill tests. A heavy initial microbial load was simulated by preparing bacterial inoculum. Numbers of viable cells were counted and reduction in microbial colony counts before and after disinfectant exposure was expressed as log reduction. RESULTS: Among the disinfectants, Novacide was most effective. All clinical MDR bacterial isolates and reference strains were killed within 30 seconds of exposure at 0.156% solution, whereas spores got killed after 30 minutes of exposure at 2.5% solution which is the recommended concentration. For Silvicide all vegetative bacteria were killed at 5% solution after 20 minutes contact time

  10. Antitumor agents 286. Design, synthesis, and structure-activity relationships of 3'R,4'R-disubstituted-2',2'-dimethyldihydropyrano[2,3-f]chromone (DSP) analogues as potent chemosensitizers to overcome multidrug resistance.

    Science.gov (United States)

    Zhou, Ting; Shi, Qian; Bastow, Kenneth F; Lee, Kuo-Hsiung

    2010-12-23

    In this study, various 3'R,4'R-disubstituted-2',2'-dimethydihydropyrano[2,3-f]chromone (DSP) derivatives were discovered as potent chemosensitizers in the treatment of multidrug resistant cancer cells. Twenty-four DSP analogues (5-28) were synthesized and evaluated against a multidrug resistant (MDR) cell line (KB-Vin) with and without vincristine (VCR). All DSP analogues exhibited low intrinsic cytotoxicity. However, in combination treatment, most DSPs reversed resistance to VCR and lowered the GI₅₀ value of VCR by 12-349-fold. At a concentration of 1 μg/mL, three compounds, 11, 14, and 21, fully reversed resistance to VCR in KB-Vin cancer cells, a 2-fold increase compared to verapamil, a first-generation chemosensitizer. Detailed structure-activity relationship (SAR) conclusions were established based on 3' and 4' substitutions. Moreover, a preliminary mechanism study indicated that the chemosensitizing activity of DSP analogues results from inhibition of P-glycoprotein (P-gp) overexpressed in MDR cancer cells.

  11. Multidrug resistant Gram-negative bacilli in lower respiratory tract infections.

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    Shashidhar Vishwanath

    2013-12-01

    Full Text Available Lower respiratory tract infections are among important causes of morbidity and mortality for all age groups. The emergence of multidrug resistant Gram-negative bacilli is an issue of increasing concern.A retrospective study including respiratory specimens (sputum and BAL was conducted in our tertiary care centre. Samples were processed for microscopy, culture and susceptibility testing following standard methods. Multidrug resistant Gram-negative bacilli causing lower respiratory tract infections were studied for their causation of disease. The effect of appropriate treatment on clinical outcome was observed.A total of 472 Gram-negative pathogens were isolated from sputum and broncho-alveolar lavage fluid specimens during the study period. Among these Gram-negative pathogens 175 (37% were found to be multidrug resistant. Klebsiella pneumoniae 85 (48.6% and Acinetobacter spp. 59 (33.7% were the predominant multidrug resistant Gram-negative bacilli isolated. Based on clinico-microbiological correlation, 138 (78.9% multidrug resistant isolates were found to be pathogenic and the rest 37 (21.1% were considered as colonizers. After initiating appropriate antibiotic therapy, clinical improvement was seen in 110 (79.7% patients. In the patients who showed improvement, amikacin (34.3% and cefoperazone-sulbactum (21.8% were found to be the most effective drugs.A large majority of the isolated multidrug resistant Gram-negative bacilli were found to be pathogenic. Regular surveillance which directs appropriate empirical therapy; and good clinic-microbiological workup of each case of lower respiratory tract infection can reduce the morbidity and mortality associated with multidrug resistant organisms.

  12. Multidrug resistance 1 gene polymorphisms may determine Crohn's disease behavior in patients from Rio de Janeiro

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    Ana Teresa P. Carvalho

    2014-01-01

    Full Text Available OBJECTIVES: Conflicting data from studies on the potential role of multidrug resistance 1 gene polymorphisms in inflammatory bowel disease may result from the analysis of genetically and geographically distinct populations. Here, we investigated whether multidrug resistance 1 gene polymorphisms are associated with inflammatory bowel diseases in patients from Rio de Janeiro. METHODS: We analyzed 123 Crohn's disease patients and 83 ulcerative colitis patients to determine the presence of the multidrug resistance 1 gene polymorphisms C1236T, G2677T and C3435T. In particular, the genotype frequencies of Crohn's disease and ulcerative colitis patients were analyzed. Genotype-phenotype associations with major clinical characteristics were established, and estimated risks were calculated for the mutations. RESULTS: No significant difference was observed in the genotype frequencies of the multidrug resistance 1 G2677T/A and C3435T polymorphisms between Crohn's disease and ulcerative colitis patients. In contrast, the C1236T polymorphism was significantly more common in Crohn's disease than in ulcerative colitis (p = 0.047. A significant association was also found between the multidrug resistance 1 C3435T polymorphism and the stricturing form of Crohn's disease (OR: 4.13; p = 0.009, whereas no association was found with penetrating behavior (OR: 0.33; p = 0.094. In Crohn's disease, a positive association was also found between the C3435T polymorphism and corticosteroid resistance/refractoriness (OR: 4.14; p = 0.010. However, no significant association was found between multidrug resistance 1 gene polymorphisms and UC subphenotypic categories. CONCLUSION: The multidrug resistance 1 gene polymorphism C3435T is associated with the stricturing phenotype and an inappropriate response to therapy in Crohn's disease. This association with Crohn's disease may support additional pathogenic roles for the multidrug resistance 1 gene in regulating gut

  13. Molecular characterization of multidrug resistant hospital isolates using the antimicrobial resistance determinant microarray.

    Directory of Open Access Journals (Sweden)

    Tomasz A Leski

    Full Text Available Molecular methods that enable the detection of antimicrobial resistance determinants are critical surveillance tools that are necessary to aid in curbing the spread of antibiotic resistance. In this study, we describe the use of the Antimicrobial Resistance Determinant Microarray (ARDM that targets 239 unique genes that confer resistance to 12 classes of antimicrobial compounds, quaternary amines and streptothricin for the determination of multidrug resistance (MDR gene profiles. Fourteen reference MDR strains, which either were genome, sequenced or possessed well characterized drug resistance profiles were used to optimize detection algorithms and threshold criteria to ensure the microarray's effectiveness for unbiased characterization of antimicrobial resistance determinants in MDR strains. The subsequent testing of Acinetobacter baumannii, Escherichia coli and Klebsiella pneumoniae hospital isolates revealed the presence of several antibiotic resistance genes [e.g. belonging to TEM, SHV, OXA and CTX-M classes (and OXA and CTX-M subfamilies of β-lactamases] and their assemblages which were confirmed by PCR and DNA sequence analysis. When combined with results from the reference strains, ~25% of the ARDM content was confirmed as effective for representing allelic content from both Gram-positive and -negative species. Taken together, the ARDM identified MDR assemblages containing six to 18 unique resistance genes in each strain tested, demonstrating its utility as a powerful tool for molecular epidemiological investigations of antimicrobial resistance in clinically relevant bacterial pathogens.

  14. Treatment of multidrug-resistant pseudomonas aeruginosa using extended-infusion antimicrobial regimens.

    Science.gov (United States)

    Heil, Emily L; Lowery, Ashleigh V; Thom, Kerri A; Nicolau, David P

    2015-01-01

    In the management of multidrug-resistant infections in critically ill patients with multiorgan dysfunction, consideration must be given to the pharmacokinetics and pharmacodynamics of an antimicrobial agent to optimize dosing. We describe a 25-year-old woman who was undergoing thrice-weekly hemodialysis and developed multidrug-resistant Pseudomonas aeruginosa bacteremia secondary to infected left and right ventricular assist devices. After multiple courses of antibiotics, her blood cultures revealed that the infecting organism was becoming progressively more resistant to antibiotic options. Cefepime 2 g administered over 3 hours/day (in combination with colistimethate) provided adequate drug levels for multidrug-resistant, cefepime-intermediate P. aeruginosa bacteremia in this patient. We present the clinical case of this patient, followed by a discussion of possible therapeutic approaches to be considered, including illustration of the principles of using extended-infusion antimicrobial regimens, and present the patient's resulting clinical course.

  15. Reversal in multidrug resistance by magnetic nanoparticle of Fe3O4 loaded with adriamycin and tetrandrine in K562/A02 leukemic cells

    Directory of Open Access Journals (Sweden)

    Baoan Chen

    2008-06-01

    Full Text Available Baoan Chen1,5, Qian Sun1,5, Xuemei Wang2, Feng Gao1, Yongyuan Dai1, Yan Yin1, Jiahua Ding1, Chong Gao1, Jian Cheng1, Jingyuan Li2, Xinchen Sun1, Ningna Chen1, Wenlin Xu3, Huiling Shen3, Delong Liu41Department of Hematology, Zhongda Hospital, Southeast University, Nanjing, China; 2State Key Lab of Bioelectronics(Chien-Shiung Wu Laboratory, Southeast University, Nanjing 210096, China; 3Department of Hematology, The First People’s Hospital of Zhenjiang, Zhenjiang, China; 4Westchester Medical Center, New York Medical College, NY, USA; 5These authors have contributed equally to this work.Abstract: Drug resistance is a primary hindrance for efficiency of chemotherapy. To investigate whether Fe3O4-magnetic nanoparticles (Fe3O4-MNPs loaded with adriamycin (ADM and tetrandrine (Tet would play a synergetic reverse role in multidrug resistant cell, we prepared the drug-loaded nanoparticles by mechanical absorption polymerization to act with K562 and one of its resistant cell line K562/A02. The survival of cells which were cultured with these conjugates for 48 h was observed by MTT assay. Using cells under the same condition described before, we took use of fluorescence microscope to measure fluorescence intensity of intracellular ADM at an excitation wavelength of 488 nm. P-glycoprotein (P-gp was analyzed with flow cytometer. The expression of mdr1 mRNA was measured by RT-PCR. The results showed that the growth inhibition efficacy of both the two cells increased with augmenting concentrations of Fe3O4-MNPs which were loaded with drugs. No linear correlation was found between fluorescence intensity of intracellular adriamycin and augmenting concentration of Fe3O4-MNPs. Tet could downregulate the level of mdr-1 gene and decrease the expression of P-gp. Furthermore, Tet polymerized with Fe3O4-MNPs reinforced this downregulation, causing a 100-fold more decrease in mdr1 mRNA level, but did not reduce total P-gp content. Our results suggest that Fe3O4-MNPs

  16. Virulence and genomic feature of multidrug resistant Campylobacter jejuni isolated from broiler chicken

    Directory of Open Access Journals (Sweden)

    Haihong Hao

    2016-10-01

    Full Text Available The aim of this study was to reveal the molecular mechanism involved in multidrug resistance and virulence of Campylobacter jejuni isolated from broiler chickens. The virulence of six multidrug resistant C. jejuni was determined by in vitro and in vivo methods. The de novo whole genome sequencing technology and molecular biology methods were used to analyze the genomic features associated with the multidrug resistance and virulence of a selected isolate (C. jejuni 1655. The comparative genomic analyses revealed a large number of single nucleotide polymorphisms, deletions, rearrangements, and inversions in C. jejuni 1655 compared to reference C. jejuni genomes. The co-emergence of Thr-86-Ile mutation in gyrA gene, A2075G mutation in 23S rRNA gene, tetO, aphA and aadE genes and pTet plasmid in C. jejuni 1655 contributed its multidrug resistance to fluoroquinolones, macrolides, tetracycline and aminoglycosides. The combination of multiple virulence genes may work together to confer the relative higher virulence in C. jejuni 1655. The co-existence of mobile gene elements (e.g. pTet and CRISPR-Cas system in C. jejuni 1655 may play an important role in the gene transfer and immune defense. The present study provides basic information of phenotypic and genomic features of C. jejuni 1655, a strain recently isolated from a chicken displaying multidrug resistance and relatively high level of virulence.

  17. Virulence and Genomic Feature of Multidrug Resistant Campylobacter jejuni Isolated from Broiler Chicken

    Science.gov (United States)

    Hao, Haihong; Ren, Ni; Han, Jing; Foley, Steven L.; Iqbal, Zahid; Cheng, Guyue; Kuang, Xiuhua; Liu, Jie; Liu, Zhenli; Dai, Menghong; Wang, Yulian; Yuan, Zonghui

    2016-01-01

    The aim of this study was to reveal the molecular mechanism involved in multidrug resistance and virulence of Campylobacter jejuni isolated from broiler chickens. The virulence of six multidrug resistant C. jejuni was determined by in vitro and in vivo methods. The de novo whole genome sequencing technology and molecular biology methods were used to analyze the genomic features associated with the multidrug resistance and virulence of a selected isolate (C. jejuni 1655). The comparative genomic analyses revealed a large number of single nucleotide polymorphisms, deletions, rearrangements, and inversions in C. jejuni 1655 compared to reference C. jejuni genomes. The co-emergence of Thr-86-Ile mutation in gyrA gene, A2075G mutation in 23S rRNA gene, tetO, aphA and aadE genes and pTet plasmid in C. jejuni 1655 contributed its multidrug resistance to fluoroquinolones, macrolides, tetracycline, and aminoglycosides. The combination of multiple virulence genes may work together to confer the relative higher virulence in C. jejuni 1655. The co-existence of mobile gene elements (e.g., pTet) and CRISPR-Cas system in C. jejuni 1655 may play an important role in the gene transfer and immune defense. The present study provides basic information of phenotypic and genomic features of C. jejuni 1655, a strain recently isolated from a chicken displaying multidrug resistance and relatively high level of virulence. PMID:27790202

  18. Mutational and acquired carbapenem resistance mechanisms in multidrug resistant Pseudomonas aeruginosa clinical isolates from Recife, Brazil

    Science.gov (United States)

    Cavalcanti, Felipe Lira de Sá; Mirones, Cristina Rodríguez; Paucar, Elena Román; Montes, Laura Álvarez; Leal-Balbino, Tereza Cristina; de Morais, Marcia Maria Camargo; Martínez-Martínez, Luis; Ocampo-Sosa, Alain Antonio

    2015-01-01

    An investigation was carried out into the genetic mechanisms responsible for multidrug resistance in nine carbapenem-resistant Pseudomonas aeruginosaisolates from different hospitals in Recife, Brazil. Susceptibility to antimicrobial agents was determined by broth microdilution. Polymerase chain reaction (PCR) was employed to detect the presence of genes encoding β-lactamases, aminoglycoside-modifying enzymes (AMEs), 16S rRNA methylases, integron-related genes and OprD. Expression of genes coding for efflux pumps and AmpC cephalosporinase were assessed by quantitative PCR. The outer membrane proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The blaSPM-1, blaKPC-2 and blaGES-1 genes were detected in P. aeruginosaisolates in addition to different AME genes. The loss of OprD in nine isolates was mainly due to frameshift mutations, premature stop codons and point mutations. An association of loss of OprD with the overexpression of MexAB-OprM and MexXY-OprM was observed in most isolates. Hyper-production of AmpC was also observed in three isolates. Clonal relationship of the isolates was determined by repetitive element palindromic-PCR and multilocus sequence typing. Our results show that the loss of OprD along with overexpression of efflux pumps and β-lactamase production were responsible for the multidrug resistance in the isolates analysed. PMID:26676375

  19. Folate concentration dependent transport activity of the Multidrug Resistance Protein 1 (ABCC1).

    NARCIS (Netherlands)

    Hooijberg, J.H.; Jansen, G.; Assaraf, Y.G.; Kathmann, I.; Pieters, R.; Laan, AC; Veerman, A.J.P.; Kaspers, G.J.L.; Peters, G.J.

    2004-01-01

    The Multidrug Resistance Protein MRP1 (ABCC1) can confer resistance to a variety of therapeutic drugs. In addition, MRP1/ABCC1 mediates cellular export of natural folates, such as folic acid and l-leucovorin. In this study we determined whether cellular folate status affected the functional activity

  20. Role of multidrug resistance protein (MRP) in glutathione S-conjugate transport in mammalian cells

    NARCIS (Netherlands)

    Muller, M; deVries, EGE; Jansen, PLM

    1996-01-01

    The human multidrug resistance protein (MRP), a 190-kDa member of the ABC-protein superfamily, is an ATP-dependent glutathione S-conjugate carrier (GS-X pump) and is present in membranes of many, if not all, cells, Overexpression of MRP in tumor cells contributes to resistance to natural product dru

  1. Multidrug resistance in oncology and beyond : from imaging of drug efflux pumps to cellular drug targets

    NARCIS (Netherlands)

    Nagengast, Wouter B; Oude Munnink, Thijs H; Dijkers, Eli; Hospers, Geesiena; Brouwers, Adrienne H; Schröder, Carolien P; Lub-de Hooge, Marjolijn; de Vries, Elisabeth G E

    2010-01-01

    Resistance of tumor cells to several structurally unrelated classes of natural products, including anthracyclines, taxanes, and epipodophyllotoxines, is often referred as multidrug resistance (MDR). This is associated with ATP-binding cassette transporters, which function as drug efflux pumps such a

  2. Molecular characterisation of multidrug-resistant Salmonella enterica serovar Typhimurium isolates from Gomel region, Belarus

    DEFF Research Database (Denmark)

    Tapalski, D.; Hendriksen, Rene S.; Hasman, Henrik;

    2007-01-01

    an infection outside hospitals in the Gomel region of Belarus. Thirty-one isolates were highly similar according to PFGE and MLVA typing, were multidrug-resistant, including resistance to ceftiofur, and harboured the bla(CTX-M-5) gene. These results indicate that a common source may have been responsible...

  3. Highly successful treatment outcome of multidrug-resistant tuberculosis in the Netherlands, 2000-2009

    NARCIS (Netherlands)

    van Altena, R.; de Vries, G.; Haar, C. H.; de Lange, W. C. M.; Magis-Escurra, C.; van den Hof, S.; van Soolingen, D.; Boeree, M. J.; van der Werf, T. S.

    2015-01-01

    SETTING: Resistance to the two key anti-tuberculosis drugs isoniazid and rifampicin is a characteristic of multidrug-resistant tuberculosis (MDR-TB). MDR-TB is a scourge requiring toxic, prolonged treatment and is associated with poor outcomes. The Netherlands is a country with a long-standing, inte

  4. Multi-drug resistant tuberculosis in the Netherlands : Personalised treatment and outcome

    NARCIS (Netherlands)

    van Altena, Richard

    2016-01-01

    Tuberculosis (TB) caused by bacilli that are resistant to the two major drugs, rifampicin and isoniazid is defined as Multi-Drug Resistant TB or MDRTB. MDRTB kills around 50% of people affected around the world. In contrast, treatment results of MDR-TB in the Netherlands (1985-2013) have consistentl

  5. Biofilm-Forming Capability of Highly Virulent, Multidrug-Resistant Candida auris

    Science.gov (United States)

    Sherry, Leighann; Ramage, Gordon; Kean, Ryan; Borman, Andrew; Johnson, Elizabeth M.; Richardson, Malcolm D.

    2017-01-01

    The emerging multidrug-resistant yeast pathogen Candida auris has attracted considerable attention as a source of healthcare–associated infections. We report that this highly virulent yeast has the capacity to form antifungal resistant biofilms sensitive to the disinfectant chlorhexidine in vitro. PMID:28098553

  6. Multidrug-Resistant Bacteroides fragilis Bacteremia in a US Resident: An Emerging Challenge

    Directory of Open Access Journals (Sweden)

    Cristian Merchan

    2016-01-01

    Full Text Available We describe a case of Bacteroides fragilis bacteremia associated with paraspinal and psoas abscesses in the United States. Resistance to b-lactam/b-lactamase inhibitors, carbapenems, and metronidazole was encountered despite having a recent travel history to India as the only possible risk factor for multidrug resistance. Microbiological cure was achieved with linezolid, moxifloxacin, and cefoxitin.

  7. Spinosad is a potent inhibitor of canine P-glycoprotein

    NARCIS (Netherlands)

    Schrickx, Johannes A

    2014-01-01

    Inhibition of the drug transporter P-glycoprotein (P-gp) by the oral flea preventative spinosad has been suggested as the underlying cause of the drug-drug interaction with ivermectin. In this study, an in vitro model consisting of canine cells was validated to describe the inhibitory effect of drug

  8. Establishment of a P-glycoprotein substrate screening model and its preliminary application

    Institute of Scientific and Technical Information of China (English)

    Yi Wang; Jiang Cao; Su Zeng

    2004-01-01

    AIM: To establish a high P-glycoprotein (P-gp) expressing cell line as a model for studying drug absorption and distribution, and to explore the preliminary application of this screening model.METHODS: A full-length MDR1 cDNA fragment in plasmid pMDRA1 was first subcloned into plasmid pET28a(+), then MDR1 cDNA was cut from the recombinant plasmid with double-digestion and ligated into the mammalian expression vector pcDNA3.1(+). The recombinant plasmid pcDNA3.1(+)/MDR1 was transfected into breast cancer cell line Bcap37using the Superfect transfection reagent. Several stably transfected clones were obtained after selection with G418.Real-time fluorescent quantitative RT- PCR and Western blot methods were used to detect the expression of P-gp, and the cellular location of the expressed protein was determined by immunohistochemical staining. Drug sensitivity assay was used to evaluate the biological function of expressed P-gp.Concentration of quercetin in cells was determined by highperformance liquid chromatography (HPLC).RESULTS: The recombinant plasmid was confirmed to be inserted in the correct orientation by restrictive enzyme digestion and DNA sequencing. Real-time fluorescent quantitative RT-PCR showed a higher level of P-cp mRNA in transfected cells compared to that in the control cells, and the Western blot result also indicated that P-gp expression in transfected cells was higher than that in control cells. The immunohistochemical staining showed that the expressed P-gp was localized on cell membranes. Drug sensitivity assay showed that the IC50 for adriamycin and colchicine of the transfected cells was higher than that of the control cells.The concentration of quercetin in model cells was lower than that in control cells by HPLC. After P-gp inhibitor verapamil was administered, the concentration of quercetin in model cells was increased.CONCLUSION: A high P-gp expressing ceil line can be established, which could provide a suitable in vitro model system for

  9. P glycoprotein: a new mechanism to control drug-induced nephrotoxicity.

    Science.gov (United States)

    del Moral, R G; Olmo, A; Aguilar, M; O'Valle, F

    1998-01-01

    The role of P glycoprotein (P-gp) in kidney is now being explored, and under physiological conditions, this protein is thought to be an excretory pump of cationic xenobiotics and metabolites. Functionally, two different types of P-gp have been described, but only the class I has been related to drug transport, and its overexpression confers the multidrug resistance phenotype in tumoral cells. It has been proposed that P-gp is involved in the energy-dependent transport of substrates through the cell membrane (toxic metabolites, toxins, nutrients, ions, peptides, etc.)--like a 'hydrophobic molecule vacuum cleaner'. Several physiological functions have been attributed to P-gp: defense against xenobiotic aggression and transmembrane transport of prenylcysteine methyl esters, removing these cytotoxic metabolites from cells. A variety of substrates ranging from chemotherapeutics to steroid hormones, antibiotics, and calcium channel blockers can be transported by P-gp, suggesting the possible involvement of this protein in other unknown functions. Results from our group and others have suggested that overexpression of P-gp in renal tubular and mesangial cells prevents pharmacological nephrotoxicity by cyclosporin A (CsA). On the other hand CsA, a substrate of the pump, could act as a blocker in tubular cells by competitive inhibition. One relevant aspect in kidney is the possible relationship between P-gp and protein kinase C. Several reports suggest that protein kinase C may play a role in inducing the P-gp overexpression in cells under xenobiotic pressure, through activation of the ras oncoprotein family. This could be mediated directly by angiotensin II as a ras activator. This way, the detoxicant function of P-gp against products of the ras catabolism could mediate their accumulation when the 'vacuum cleaner' function is blocked by CsA or tacrolimus, contributing to the initial development of fibroblastic activation that leads to interstitial fibrosis associated with

  10. Enterococcus faecalis as multidrug resistance strains in clinical isolates in Imam Reza Hospital in Kermanshah, Iran.

    Science.gov (United States)

    Mohammadi, F; Ghafourian, S; Mohebi, R; Taherikalani, M; Pakzad, I; Valadbeigi, H; Hatami, V; Sadeghifard, N

    2015-01-01

    The current study aimed to investigate the prevalence of vancomycin-resistant Enterococcus in E. faecalis and E. faecium and antimicrobial susceptibility patterns, then dominant genes responsible for vancomycin resistance were determined. For this propose, 180 clinical isolates of Enterococcus were subjected for identification and antibiotic susceptibility assay. Then, the gene responsible vancomycin resistant strains were determined. The results demonstrated the E. faecalis as a dominant Enterococcus. Resistance to erythromycin was dominant and multidrug resistance strains observed in E. faecalis. vanA was responsible for vancomycin resistance. In conclusion, a high rate of resistance to antibiotics in Enterococcus is clearly problematic, and a novel strategy is needed to decrease resistance in Enterococcus.

  11. Electroporation adopting trains of biphasic pulses enhances in vitro and in vivo the cytotoxic effect of doxorubicin on multidrug resistant colon adenocarcinoma cells (LoVo).

    Science.gov (United States)

    Meschini, Stefania; Condello, Maria; Lista, Pasquale; Vincenzi, Bruno; Baldi, Alfonso; Citro, Gennaro; Arancia, Giuseppe; Spugnini, Enrico P

    2012-09-01

    Few articles in the literature have focused on electroporation as a strategy to reverse multidrug resistance (MDR) of tumour cells and they are mostly limited to the improved efficacy of bleomycin. We tested the application of trains of biphasic pulses to cell suspensions and to murine xenografts as a strategy to increase the uptake of doxorubicin (DOX) and to enhance its cytotoxicity against chemoresistant cells. The human colon adenocarcinoma cell line LoVo DX, expressing MDR phenotype with high levels of P-glycoprotein (P-gp), has been used. The in vitro and in vivo studies gave the following results: (i) the application of the electric pulses to the cell suspension, immediately before DOX administration, induced a significant increase of drug retention; (ii) confocal microscopy observations showed a remarkable increase of intranuclear accumulation of DOX induced by electroporation; (iii) cell survival assay revealed a decrease of cell viability in the cultures treated with the combination of electroporation and doxorubicin; (iv) scanning electron microscopy observations revealed consistent morphological changes after the combined exposure to electroporation and doxorubicin; (v) in implanted mice the combined treatment induced an evident slowdown on the tumour growth when compared to treatment with DOX alone; (vi) histopathological analysis evidenced tumour destruction and its replacement by scar tissue in the tumours treated with the combination of doxorubicin and electroporation.

  12. Multidrug Resistant Salmonella typhi in Asymptomatic Typhoid Carriers among Food Handlers in Namakkal District, Tamil Nadu

    Directory of Open Access Journals (Sweden)

    Senthilkumar B

    2005-01-01

    Full Text Available Purpose: to screen Salmonella typhi in asymptomatic typhoid carriers and to find out drug resistance and ability of the strains to transmit drug resistance to other bacteria. Methods: Cultural characters, biochemical tests, antibiotic sensitivity test (disc diffusion, agarose gel electrophoresis, and conjugation protocols were done. Thirty five stool samples were collected from the suspected food handlers for the study. Results: Among 35 samples, (17.14% yielded a positive result. Out of these 4 (20.0% were women and 2 (13.33% were men. The isolates were tested with a number of conventional antibiotics viz, amikacin, amoxicillin, ampicillin, chloramphenicol, ciprofloxacin, co-trimaxazole, rifampicin, gentamicin, nalidixic acid, ofloxacin and tetracycline. Five isolates were having the multidrug resistant character. Four (66.66% multidrug resistant isolates were found to have plasmids, while one (16.66% multidrug resistant isolate had no plasmid and the chromosome encoded the resistance. Only one strain (16.66% showed single antibiotic resistance in the study and had no plasmid DNA. The molecular weights of the plasmids were determined and found to be 120 kb.The mechanism of spreading of drug resistance through conjugation process was analyzed. In the conjugation studies, the isolates having R+ factor showed the transfer of drug resistance through conjugation, which was determined by the development of antibiotic resistance in the recipients. Conclusion: This study shows that drug resistant strains are able to transfer genes encoding drug resistance.

  13. Multidrug-resistant Pseudomonas aeruginosa and Acinetobacter baumannii: resistance mechanisms and implications for therapy.

    Science.gov (United States)

    Zavascki, Alexandre P; Carvalhaes, Cecília G; Picão, Renata C; Gales, Ana C

    2010-01-01

    Pseudomonas aeruginosa and Acinetobacter baumannii are major nosocomial pathogens worldwide. Both are intrinsically resistant to many drugs and are able to become resistant to virtually any antimicrobial agent. An increasing prevalence of infections caused by multidrug-resistant (MDR) isolates has been reported in many countries. The resistance mechanisms of P. aeruginosa and A. baumannii include the production of beta-lactamases, efflux pumps, and target-site or outer membrane modifications. Resistance to multiple drugs is usually the result of the combination of different mechanisms in a single isolate or the action of a single potent resistance mechanism. There are many challenges in the treatment of MDR P. aeruginosa and A. baumannii, especially considering the absence of new antimicrobials in the drug-development pipeline. In this review, we present the major resistance mechanisms of P. aeruginosa and A. baumannii, and discuss how they can affect antimicrobial therapy, considering recent clinical, microbiological, pharmacokinetic and pharmacodynamic findings of the main drugs used to treat MDR isolates.

  14. Identification of mutations conferring streptomycin resistance in multidrug-resistant tuberculosis of China.

    Science.gov (United States)

    Zhao, Li-Li; Liu, Hai-Can; Sun, Qing; Xiao, Tong-Yang; Zhao, Xiu-Qin; Li, Gui-Lian; Zeng, Chun-Yan; Wan, Kang-Lin

    2015-10-01

    We investigated the spectrum and frequency of mutations in rpsL, rrs, and gidB among 140 multidrug-resistant tuberculosis (MDR-TB) clinical isolates from China. The association between mutations and different genotypes was also analyzed. Our data revealed that 65.7% of MDR-TB were resistant to streptomycin (STR), and 90.2% of STR-resistant isolates were Beijing strains. STR resistance was correlated with Beijing family (P=0.00). Compared with phenotypic data, detection of mutations for the combination of these 3 genes exhibited 94.6% sensitivity, 91.7% specificity, and 93.6% accuracy. The most common mutations in STR-resistant isolates were rpsL128, 262, and rrs514, of which rpsL128 showed association with Beijing lineage (P=0.00). A combination of these 3 mutations can serve as the reliable predictors for STR resistance, showing the sensitivity, specificity, and accuracy of 85.9%, 97.9%, and 90.0%, respectively. Furthermore, gidBA276C, not A615G, was Beijing lineage specific. These findings are useful to develop rapid molecular diagnostic methods for STR resistance in China.

  15. Inhibition of mTOR Pathway by Rapamycin Decreases P-glycoprotein Expression and Spontaneous Seizures in Pharmacoresistant Epilepsy.

    Science.gov (United States)

    Chi, Xiaosa; Huang, Cheng; Li, Rui; Wang, Wei; Wu, Mengqian; Li, Jinmei; Zhou, Dong

    2017-04-01

    The mammalian target of rapamycin (mTOR) has been demonstrated to mediate multidrug resistance in various tumors by inducing P-glycoprotein (P-gp) overexpression. Here, we investigated the correlation between the mTOR pathway and P-gp expression in pharmacoresistant epilepsy. Temporal cortex specimens were obtained from patients with refractory mesial temporal lobe epilepsy (mTLE) and age-matched controls who underwent surgeries at West China Hospital of Sichuan University between June 2014 and May 2015. We established a rat model of epilepsy kindled by coriaria lactone (CL) and screened pharmacoresistant rats (non-responders) using phenytoin. Non-responders were treated for 4 weeks with vehicle only or with the mTOR pathway inhibitor rapamycin at doses of 1, 3, and 6 mg/kg. Western blotting and immunohistochemistry were used to detect the expression of phospho-S6 (P-S6) and P-gp at different time points (1 h, 8 h, 1 day, 3 days, 1 weeks, 2 weeks, and 4 weeks) after the onset of treatment. Overexpression of P-S6 and P-gp was detected in both refractory mTLE patients and non-responder rats. Rapamycin showed an inhibitory effect on P-S6 and P-gp expression 1 week after treatment in rats. In addition, the expression levels of P-S6 and P-gp in the 6 mg/kg group were significantly lower than those in the 1 mg/kg or the 3 mg/kg group at the same time points (all P P P-gp expression in drug-resistant epilepsy. Inhibition of the mTOR pathway by rapamycin may be a potential therapeutic approach for pharmacoresistant epilepsy.

  16. Selective induction of P-glycoprotein at the CNS barriers during symptomatic stage of an ALS animal model.

    Science.gov (United States)

    Chan, Gary N Y; Evans, Rebecca A; Banks, David B; Mesev, Emily V; Miller, David S; Cannon, Ronald E

    2017-02-03

    P-glycoprotein (P-gp), Breast cancer resistance protein (BCRP) and Multidrug resistance-associated protein 2 (MRP2) residing at the blood-brain barrier (BBB) and the blood-spinal cord barrier (BSCB) are major obstacles for drug delivery to the Central Nervous System (CNS). Disease-induced changes of these xenobiotic transporters at the CNS barriers have been previously documented. Changes in the functional expression of these transporters at the CNS barriers would limit the clinical efficacy of therapeutic agents targeting the CNS. In this study, we characterized the changes in expression and efflux activity of P-gp, BCRP and MRP2 at the BBB and BSCB of an amyotrophic lateral sclerosis (ALS) SOD1-G93A transgenic rat model across the three stages of disease progression: pre-onset, onset and symptomatic. Up-regulation of P-gp and BCRP at the BBB and BSCB during disease progression of ALS would reduce drug entry to the CNS, while any decreases in transport activity would increase drug entry. In SOD rats at the ALS symptomatic stage, we observed increases in both P-gp transport activity and expression compared to age-matched wildtypes. BCRP and MRP2 levels were unchanged in these animals. Immunohistochemical analysis in brain and spinal cord capillaries of SOD rats from all three ALS stages and age-matched wildtypes showed no differences in nuclear localization of a known P-gp regulator, nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB). It suggests that NFκB may have a limited role during P-gp induction observed in our study and additional signaling pathways could be responsible for this response. Our observations imply that novel pharmacological approaches for treating ALS require selecting drugs that are not P-gp substrates in order to improve therapeutic efficacy in the CNS during ALS progression.

  17. Reversal of HCC Drug Resistance by Using Hammerhead Ribozymes against Multidrug Resistance 1 Gene

    Institute of Scientific and Technical Information of China (English)

    QIAO Sen; WANG Hai; CHEN Xiaoping

    2005-01-01

    To reverse multidrug resistance(MDR) of HepG2 by anti-MDR1 hammerhead ribozyme,an anti-MDR1 hammerhead ribozyme was developed and delivered to P-gp-overproducing human hepatocarcinoma cell line HepG2 by a retroviral vector containing RNA polymerase Ⅲ promoter.The expression of mdr1/Pgp and Rz was detected in HepG2, HepG2 multidrug-resistant cell line and HepG2 Rz-transfected cells by semi quantitative RT-PCR and Western blot methods. Moreover, MTT assay was employed to detect the sensitivity of these ribozyme-transfected cells, and Rhodamine123 (Rh123) was used to test the function of Pgp. The Rz- transfected HepG2 cells became doxorubicin-sensitive, which was concomitant with the decreased MDR1 expression. The study showed that the retrovirus vector encoding the anti-MDR1 ribozyme may be applicable to the treatment of MDR cells.

  18. Management of patients with multidrug-resistant/extensively drug-resistant tuberculosis in Europe : a TBNET consensus statement

    NARCIS (Netherlands)

    Lange, Christoph; Abubakar, Ibrahim; Alffenaar, Jan-Willem C.; Bothamley, Graham; Caminero, Jose A.; Carvalho, Anna Cristina C.; Chang, Kwok-Chiu; Codecasa, Luigi; Correia, Ana; Crudu, Valeriu; Davies, Peter; Dedicoat, Martin; Drobniewski, Francis; Duarte, Raquel; Ehlers, Cordula; Erkens, Connie; Goletti, Delia; Guenther, Gunar; Ibraim, Elmira; Kampmann, Beate; Kuksa, Liga; de lange, Wiel; van Leth, Frank; van Lunzen, Jan; Matteelli, Alberto; Menzies, Dick; Monedero, Ignacio; Richter, Elvira; Ruesch-Gerdes, Sabine; Sandgren, Andreas; Scardigli, Anna; Skrahina, Alena; Tortoli, Enrico; Volchenkov, Grigory; Wagner, Dirk; van der Werf, Marieke J.; Williams, Bhanu; Yew, Wing-Wai; Zellweger, Jean-Pierre; Cirillo, Daniela Maria

    2014-01-01

    The emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB) substantially challenges TB control, especially in the European Region of the World Health Organization, where the highest prevalence of MDR/XDR cases is reported. The current management of patients wit

  19. Impact of Genetic Polymorphisms of ABCB1 (MDR1, P-Glycoprotein) on Drug Disposition and Potential Clinical Implications: Update of the Literature.

    Science.gov (United States)

    Wolking, Stefan; Schaeffeler, Elke; Lerche, Holger; Schwab, Matthias; Nies, Anne T

    2015-07-01

    ATP-binding cassette transporter B1 (ABCB1; P-glycoprotein; multidrug resistance protein 1) is an adenosine triphosphate (ATP)-dependent efflux transporter located in the plasma membrane of many different cell types. Numerous structurally unrelated compounds, including drugs and environmental toxins, have been identified as substrates. ABCB1 limits the absorption of xenobiotics from the gut lumen, protects sensitive tissues (e.g. the brain, fetus and testes) from xenobiotics and is involved in biliary and renal secretion of its substrates. In recent years, a large number of polymorphisms of the ABCB1 [ATP-binding cassette, sub-family B (MDR/TAP), member 1] gene have been described. The variants 1236C>T (rs1128503, p.G412G), 2677G>T/A (rs2032582, p.A893S/T) and 3435C>T (rs1045642, p.I1145I) occur at high allele frequencies and create a common haplotype; therefore, they have been most widely studied. This review provides an overview of clinical studies published between 2002 and March 2015. In summary, the effect of ABCB1 variation on P-glycoprotein expression (messenger RNA and protein expression) and/or activity in various tissues (e.g. the liver, gut and heart) appears to be small. Although polymorphisms and haplotypes of ABCB1 have been associated with alterations in drug disposition and drug response, including adverse events with various ABCB1 substrates in different ethnic populations, the results have been majorly conflicting, with limited clinical relevance. Future research activities are warranted, considering a deep-sequencing approach, as well as well-designed clinical studies with appropriate sample sizes to elucidate the impact of rare ABCB1 variants and their potential consequences for effect sizes.

  20. Enhanced de novo ceramide generation through activation of serine palmitoyltransferase by the P-glycoprotein antagonist SDZ PSC 833 in breast cancer cells.

    Science.gov (United States)

    Wang, Hongtao; Giuliano, Armando E; Cabot, Myles C

    2002-07-01

    SDZ PSC 833 (PSC 833), a P-glycoprotein-targeted multidrug resistance modulator, sensitizes cancer cells to chemotherapy. Here we show that PSC 833 also potentiates the formation of ceramide. Because ceramide is a second messenger in chemotherapy-induced apoptosis, knowledge of the lipid pathways influenced by PSC 833 is of relevance. In intact MDA-MB 468 breast cancer cells, ceramide generation increased 3-fold 1 h after PSC 833 addition (5.0 microM). Cyclosporine A, a structural analogue, failed to impact ceramide metabolism. Sphinganine, the upstream precursor of ceramide, also increased in response to PSC 833, and this could be blocked by adding L-cycloserine, a serine palmitoyltransferase (SPT) inhibitor. Exposure of cultured cells to PSC 833 (30 min to 4 h; 1-10 microM), followed by isolation of microsomes for in vitro assay, increased SPT activity 60%, whereas palmitoyl CoA synthetase and ceramide synthase activities were not altered. SPT activity was also heightened by pretreating cells with either paclitaxel, N-(4-hydroxyphenyl)retinamide, etoposide, or daunorubicin; however, activation was half that attained by PSC 833. PSC 833 stimulated ceramide generation in other breast cancer cell lines as well, including BT-20, MDA-MB 231, Hs 578T, T-47D, and MCF-7. In summary, several types of anticancer agents and the P-glycoprotein modulator PSC 833 share the ability to increase cellular ceramide levels by activation of SPT, the rate-limiting enzyme in the de novo pathway of ceramide synthesis. These data provide novel insight in the area of lipid-mediated cell death.

  1. Multidrug resistance and ESBL-producing Salmonella spp. isolated from broiler processing plants

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    Rosangela Estel Ziech

    2016-03-01

    Full Text Available Abstract The aim of this study was to investigate the occurrence of multidrug-resistant, extended spectrum beta-lactamase (ESBL producing Salmonella spp. isolated from conveyor belts of broiler cutting rooms in Brazilian broiler processing plants. Ninety-eight strains of Salmonella spp. were analyzed. Multidrug resistance was determined by the disk diffusion test and the susceptibility of the isolated bacteria was evaluated against 18 antimicrobials from seven different classes. The double disk diffusion test was used to evaluate ESBL production. Of the 98 strains tested, 84 were multidrug resistant. The highest rates of resistance were against nalidixic acid (95%, tetracycline (91%, and the beta-lactams: ampicillin and cefachlor (45%, followed by streptomycin and gentamicin with 19% and 15% of strain resistance, respectively. By contrast, 97% of the strains were sensitive to chloramphenicol. 45% of the strains were positive for the presence of ESBL activity. In this study, high rates of multidrug resistance and ESBL production were observed in Salmonella spp.

  2. Multidrug resistance and ESBL-producing Salmonella spp. isolated from broiler processing plants

    Science.gov (United States)

    Ziech, Rosangela Estel; Lampugnani, Camila; Perin, Ana Paula; Sereno, Mallu Jagnow; Sfaciotte, Ricardo Antônio Pilegi; Viana, Cibeli; Soares, Vanessa Mendonça; de Almeida Nogueira Pinto, José Paes; dos Santos Bersot, Luciano

    2016-01-01

    The aim of this study was to investigate the occurrence of multidrug-resistant, extended spectrum beta-lactamase (ESBL) producing Salmonella spp. isolated from conveyor belts of broiler cutting rooms in Brazilian broiler processing plants. Ninety-eight strains of Salmonella spp. were analyzed. Multidrug resistance was determined by the disk diffusion test and the susceptibility of the isolated bacteria was evaluated against 18 antimicrobials from seven different classes. The double disk diffusion test was used to evaluate ESBL production. Of the 98 strains tested, 84 were multidrug resistant. The highest rates of resistance were against nalidixic acid (95%), tetracycline (91%), and the beta-lactams: ampicillin and cefachlor (45%), followed by streptomycin and gentamicin with 19% and 15% of strain resistance, respectively. By contrast, 97% of the strains were sensitive to chloramphenicol. 45% of the strains were positive for the presence of ESBL activity. In this study, high rates of multidrug resistance and ESBL production were observed in Salmonella spp. PMID:26887244

  3. Multidrug resistant Acinetobacter baumannii: a descriptive study in a city hospital

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    Pratap Siddharth

    2010-07-01

    Full Text Available Abstract Background Multidrug resistant Acinetobacter baumannii, (MRAB is an important cause of hospital acquired infection. The purpose of this study is to determine the risk factors for MRAB in a city hospital patient population. Methods This study is a retrospective review of a city hospital epidemiology data base and includes 247 isolates of Acinetobacter baumannii (AB from 164 patients. Multidrug resistant Acinetobacter baumannii was defined as resistance to more than three classes of antibiotics. Using the non-MRAB isolates as the control group, the risk factors for the acquisition of MRAB were determined. Results Of the 247 AB isolates 72% (177 were multidrug resistant. Fifty-eight percent (143/247 of isolates were highly resistant (resistant to imipenem, amikacin, and ampicillin-sulbactam. Of the 37 patients who died with Acinetobacter colonization/infection, 32 (86% patients had the organism recovered from the respiratory tract. The factors which were found to be significantly associated (p ≤ 0.05 with multidrug resistance include the recovery of AB from multiple sites, mechanical ventilation, previous antibiotic exposure, and the presence of neurologic impairment. Multidrug resistant Acinetobacter was associated with significant mortality when compared with sensitive strains (p ≤ 0.01. When surgical patients (N = 75 were considered separately, mechanical ventilation and multiple isolates remained the factors significantly associated with the development of multidrug resistant Acinetobacter. Among surgical patients 46/75 (61% grew a multidrug resistant strain of AB and 37/75 (40% were resistant to all commonly used antibiotics including aminoglycosides, cephalosporins, carbepenems, extended spectrum penicillins, and quinolones. Thirty-five percent of the surgical patients had AB cultured from multiple sites and 57% of the Acinetobacter isolates were associated with a co-infecting organism, usually a Staphylococcus or Pseudomonas. As

  4. Multidrug-resistant Gram-negative bacteria-resistant infections: epidemiology, clinical issues and therapeutic options

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    Matteo Bassetti

    2016-12-01

    Full Text Available In the last decade, we have witnessed a dramatic increase in the number of multidrug resistant Gram-negative (MDRGN bacterial pathogens, both in Italy and worldwide, with Enterobacteriacae (mostly Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii being the major threats in clinical practice. Inadequate empirical antimicrobial therapy of severe infections caused by MDR Enterobacteriacae has been associated with an increased morbidity and mortality. However, a careful selection of patients who may receive empirical treatment covering MDR Enterobacteriacae is important to avoid the overuse of broad-spectrum antibiotics. The aim of this review is to describe the mechanism of resistance, epidemiology, risk factors, clinical issues, and therapeutic options for MDRGN pathogens.

  5. [MOLECULAR CHARACTERISTICS OF THE MULTIDRUG-RESISTANT MYCOBACTERIUM TUBERCULOSIS STRAINS IN THE NORTHWEST RUSSIA].

    Science.gov (United States)

    Vyazovaya, A A; Mokrousov, I V; Zhuravlev, V Yu; Solovieva, N S; Otten, T F; Manicheva, O A; Vishnevsky, B I; Narvskaya, O V

    2016-01-01

    The goal of this work was to study the genotypic characteristics of the multidrug-resistant (MDR, i.e., resistant to at least rifampicine and isoniazid) Mycobacterium tuberculosis strains isolated in 2011-2012 from tuberculosis (TB) patients in the Northwest Russia. Spoligotyping of 195 M. tuberculosis isolates identified 14 different spoligotypes and assigned isolates to the genetic families Beijing (n = 162, 83%), LAM (n = 15), H3/URAL (n = 14), as well as T, Haarlem and X. Spoligotypes SIT1 (Beijing), SIT42 (LAM) and SIT262 (H3/URAL) were the most prevalent. Irrespective to the genotype, all the isolates were resistant to streptomycin. The multidrug resistance was accompanied by the resistance to ethionamide (56%), amikacin (31%), kanamycin (40%), and capreomycin (33%). The ethambutol resistance was found in 71% (n = 115) and 42% (n = 14) of the Beijing and non-Beijing strains, respectively (p Russia continues to be dominated by the Beijing family strains.

  6. Importance of inducible multidrug resistance 1 expression in HL-60 cells resistant to gemtuzumab ozogamicin.

    Science.gov (United States)

    Matsumoto, Taichi; Jimi, Shiro; Hara, Shuuji; Takamatsu, Yasushi; Suzumiya, Junji; Tamura, Kazuo

    2012-07-01

    Resistance to gemtuzumab ozogamicin (GO) hampers the effective treatment of refractory acute myeloid leukemia (AML). To clarify the mechanism of resistance to GO, HL-60 cells were persistently exposed to GO in order to establish GO-resistant HL-60 (HL-60/GOR) cells. Multidrug resistance 1 (MDR-1) was strongly expressed in HL-60/GOR cells, but not in HL-60 cells. Although withdrawal of GO after the chronic exposure of HL-60/GOR cells to this compound gradually decreased MDR-1 expression to trace levels, reintroducing GO restored high MDR-1 expression in HL-60/GOR cells, but not in HL-60 cells. These results indicate that HL-60/GOR cells acquired the ability to induce MDR-1 expression in response to GO. U0126, a MEK1/2 inhibitor, prevented GO-inducible MDR-1 expression and abrogated GO resistance in HL-60/GOR cells. These results suggest that in the clinical use of GO, inducible MDR-1 expression in tumor cells should be investigated before treatment with GO. If the cells are positive then MEK1/2 inhibitors may be effective in overcoming resistance to GO.

  7. P-glycoprotein activity in the blood-brain barrier is affected by virus-induced neuroinflammation and antipsychotic treatment.

    Science.gov (United States)

    Doorduin, Janine; de Vries, Erik F J; Dierckx, Rudi A; Klein, Hans C

    2014-10-01

    A large percentage of schizophrenic patients respond poorly to antipsychotic treatment. This could be explained by inefficient drug transport across the blood-brain barrier due to P-glycoprotein mediated efflux. P-glycoprotein activity and expression in the blood-brain barrier can be affected by inflammation and pharmacotherapy. We therefore investigated the effect of herpes simplex virus type-1 (HSV-1) induced neuroinflammation and antipsychotic treatment on P-glycoprotein activity. Rats were inoculated with HSV-1 or PBS (control) on day 0 and treated with saline, clozapine or risperidone from day 0 up until day 4 post-inoculation. Positron emission tomography with the P-glycoprotein substrate [11C]verapamil was used to assess P-glycoprotein activity at day 6 post-inoculation. Disease symptoms in HSV-1 inoculated rats increased over time and were not significantly affected by treatment. The volume of distribution (VT) of [11C]verapamil was significantly lower (10-22%) in HSV-1 inoculated rats than in control rats. In addition, antipsychotic treatment significantly affected the VT of [11C]verapamil in all brain regions, although this effect was drug dependent. In fact, VT of [11C]verapamil was significantly increased (22-39%) in risperidone treated rats in most brain regions when compared to clozapine treated rats and in midbrain when compared to saline treated rats. No interaction between HSV-1 inoculation and antipsychotic treatment on VT of [11C]verapamil was found. In this study we demonstrated that HSV-1 induced neuroinflammation increased and risperidone treatment decreased P-glycoprotein activity. This finding is of importance for the understanding of treatment resistance in schizophrenia, and warrants further investigation of the underlying mechanism and the importance in clinical practice.

  8. Expression of the human multidrug transporter in insect cells by a recombinant baculovirus

    Energy Technology Data Exchange (ETDEWEB)

    Germann, U.A.; Willingham, M.C.; Pastan, I.; Gottesman, M.M. (National Institutes of Health, Bethesda, MD (USA))

    1990-03-06

    The plasma membrane associated human multidrug resistance (MDR1) gene product, known as the 170-kDa P-glycoprotein or the multidrug transporter, acts as an ATP-dependent efflux pump for various cytotoxic agents. The authors expressed recombinant human multidrug transporter in a baculovirus expression system to obtain large quantities and further investigate its structure and mechanism of action. MDR1 cDNA was inserted into the genome of the Autographa californica nuclear polyhedrosis virus under the control of the polyhedrin promoter. Spodoptera frugiperda insect cells synthesized high levels of recombinant multidrug transporter 2-3 days after infection. The transporter was localized by immunocytochemical methods on the external surface of the plasma membranes, in the Golgi apparatus, and within the nuclear envelope. The human multidrug transporter expressed in insect cells is not susceptible to endoglycosidase F treatment and has a lower apparent molecular weight of 140,000, corresponding to the nonglycosylated precursor of its authentic counterpart expressed in multidrug-resistant cells. Labeling experiments showed that the recombinant multidrug transporter is phosphorylated and can be photoaffinity labeled by ({sup 3}H)azidopine, presumably at the same two sites as the native protein. Various drugs and reversing agents compete with the ({sup 3}H)azidopine binding reaction when added in excess, indicating that the recombinant human multidrug transporter expressed in insect cells is functionally similar to its authentic counterpart.

  9. Priorities in the prevention and control of multidrug-resistant Enterobacteriaceae in hospitals.

    LENUS (Irish Health Repository)

    Khan, A S

    2012-10-01

    Multidrug-resistant Enterobacteriaceae (MDE) are a major public health threat due to international spread and few options for treatment. Furthermore, unlike meticillin-resistant Staphylococcus aureus (MRSA), MDE encompass several genera and multiple resistance mechanisms, including extended-spectrum beta-lactamases and carbapenemases, which complicate detection in the routine diagnostic laboratory. Current measures to contain spread in many hospitals are somewhat ad hoc as there are no formal national or international guidelines.

  10. Prevalence of multidrug resistant pathogens in children with urinary tract infection: a retrospective analysis

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    Srinivasan S, Madhusudhan NS

    2014-11-01

    Full Text Available Urinary tract infection (UTI is one of the commonest medical problems in children. It can distress the child and may cause kidney damage. Prompt diagnosis and effective treatment can prevent complications in the child. But treatment of UTI in children has now become a challenge due to the emergence of multidrug resistant bacteria. Aims & Objectives: To know the bacteriological profile and susceptibility pattern of urinary tract infections in children and to know the prevalence of multidrug resistant uropathogens. Materials & Methods: A retrospective analysis was done on all paediatric urine samples for a period of one year. A total of 1581 samples were included in the study. Antimicrobial susceptibility testing was done on samples showing significant growth by Kirby-Bauer disc diffusion method. Statistical analysis: Prevalence and pattern were analyzed using proportions and percentages. Results: E.coli was the most predominant organism (56% causing UTI in children followed by Klebsiella sp (17%. Fifty three percent of gram negative organisms isolated from children were found to be multidrug resistant. Majority of E. coli isolates were found to be highly resistant to Ampicillin (91% and Cotrimoxazole (82% and highly sensitive to Imipenem (99% and Amikacin (93%. Conclusion: Paediatric UTI was common in children less than 5 years of age. Gram negative bacteria (E. coli and Klebsiella sp were more common than gram positive bacteria. Our study revealed that multidrug resistance was higher in E.coli.

  11. Epstein-Barr virus-negative aggressive natural killer-cell leukaemia with high P-glycoprotein activity and phosphorylated extracellular signal-regulated protein kinases 1 and 2

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    Sanja Perkovic

    2012-09-01

    Full Text Available Aggressive natural killer-cell leukaemia (ANKL is a rare type of disease with fulminant course and poor outcome. The disease is more prevalent among Asians than in other ethnic groups and shows strong association with Epstein-Barr virus (EBV and P-glycoprotein (P-gp expression associated with multidrug resistance. Here we present a case of a 47 year old Caucasian female with a prior medical history of azathioprine treated ulcerative colitis who developed EBV-negative form of ANKL. The patient presented with hepatosplenomegaly, fever and nausea with peripheral blood and bone marrow infiltration with up to 70% of atypical lymphoid cells positive for cCD3, CD2, CD7, CD56, CD38, CD45, TIA1 and granzyme B, and negative for sCD3, CD4, CD5, CD8, CD34 and CD123 indicative of ANKL. Neoplastic CD56+ NK-cells showed high level of P-glycoprotein expression and activity, but also strong expression of phosphorylated extracellular signal-regulated protein kinases 1 and 2 (ERK1/2 MAP kinase. The patient was treated with an intensive polychemotherapy regimen designed for treatment of acute lymphoblastic leukaemia, but one month after admission developed sepsis, coma and died of cardiorespiratory arrest. We present additional evidence that, except for the immunophenotype, leukaemic NK-cells resemble normal NK-cells in terms of P-gp functional capacity and expression of phosphorylated ERK1/2 signalling molecule. In that sense drugs that block P-glycoprotein activity and activated signalling pathways might represent new means for targeted therapy.

  12. Surveillance of multidrug resistant suppurative infection causing bacteria in hospitalized patients in an Indian tertiary care hospital

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    Nabakishore Nayak

    2014-01-01

    Conclusions: Of these S. aureus, particularly the methicillin resistant strain predominates, followed by strains of S. pyogenes and P. aeruginosa that were in the higher proportions of multidrug resistance.

  13. ABC multidrug transporters in schistosomes and other parasitic flatworms.

    Science.gov (United States)

    Greenberg, Robert M

    2013-12-01

    Schistosomiasis, a neglected tropical disease affecting hundreds of millions, is caused by parasitic flatworms of the genus Schistosoma. Treatment and control of schistosomiasis relies almost exclusively on a single drug, praziquantel (PZQ), a dangerous situation for a disease of this magnitude. Though PZQ is highly effective overall, it has drawbacks, and reports of worms showing PZQ resistance, either induced in the laboratory or isolated from the field, are disconcerting. Multidrug transporters underlie multidrug resistance (MDR), a phenomenon in which resistance to a single drug is accompanied by unexpected cross-resistance to several structurally unrelated compounds. Some of the best studied multidrug transporters are members of the ancient and very large ATP-binding cassette (ABC) superfamily of efflux transporters. ABC multidrug transporters such as P-glycoprotein (Pgp; ABCB1) are also associated with drug resistance in parasites, including helminths such as schistosomes. In addition to their association with drug resistance, however, ABC transporters also function in a wide variety of physiological processes in metazoans. In this review, we examine recent studies that help define the role of schistosome ABC transporters in regulating drug susceptibility, and in normal schistosome physiology, including reproduction and excretory activity. We postulate that schistosome ABC transporters could be useful targets for compounds that enhance the effectiveness of current therapeutics as well as for agents that act as antischistosomals on their own.

  14. Severe infection with multidrug-resistant Salmonella choleraesuis in a young patient with primary sclerosing cholangitis

    Science.gov (United States)

    Ferstl, Philip G; Reinheimer, Claudia; Jozsa, Katalin; Zeuzem, Stefan; Kempf, Volkhard AJ; Waidmann, Oliver; Grammatikos, Georgios

    2017-01-01

    Massive global spread of multidrug-resistant (MDR) Salmonella spp. expressing extended-spectrum beta-lactamase (ESBL) and additional resistance to fluoroquinolones has often been attributed to high international mobility as well as excessive use of oral antibiotics in livestock farming. However, MDR Salmonella spp. have not been mentioned as a widespread pathogen in clinical settings so far. We demonstrate the case of a 25-year-old male with primary sclerosing cholangitis who tested positive for MDR Salmonella enterica serotype Choleraesuis expressing ESBL and fluoroquinolone resistance. The pathogen was supposedly acquired during a trip to Thailand, causing severe fever, cholangitis and pancreatitis. To our knowledge, this is the first report of Salmonella enterica serotype Choleraesuis in Europe expressing such a multidrug resistance pattern. ESBL resistance of Salmonella enterica spp. should be considered in patients with obstructive biliary tract pathology and travel history in endemic countries. PMID:28373776

  15. [Antimicrobial therapy in severe infections with multidrug-resistant Gram-negative bacterias].

    Science.gov (United States)

    Duszyńska, Wiesława

    2010-01-01

    Multidrug-resistant Gram-negative bacteria pose a serious and rapidly emerging threat to patients in healthcare settings, and are especially prevalent and problematic in intensive therapy units. Recently, the emergence of pandrug-resistance in Gram-negative bacteria poses additional concerns. This review examines the clinical impact and epidemiology of multidrug-resistant Gram-negative bacteria as a cause of increased morbidity and mortality among ITU patients. Beta-lactamases, cephalosporinases and carbapenemases play the most important role in resistance to antibiotics. Despite the tendency to increased resistance, carbapenems administered by continuous infusion remain the most effective drugs in severe sepsis. Drug concentration monitoring, albeit rarely used in practice, is necessary to ensure an effective therapeutic effect.

  16. Molecular characterization of multidrug-resistant Shigella spp. of food origin.

    Science.gov (United States)

    Ahmed, Ashraf M; Shimamoto, Tadashi

    2015-02-02

    Shigella spp. are the causative agents of food-borne shigellosis, an acute enteric infection. The emergence of multidrug-resistant clinical isolates of Shigella presents an increasing challenge for clinicians in the treatment of shigellosis. Several studies worldwide have characterized the molecular basis of antibiotic resistance in clinical Shigella isolates of human origin, however, to date, no such characterization has been reported for Shigella spp. of food origin. In this study, we characterized the genetic basis of multidrug resistance in Shigella spp. isolated from 1600 food samples (800 meat products and 800 dairy products) collected from different street venders, butchers, retail markets, and slaughterhouses in Egypt. Twenty-four out of 27 Shigella isolates (88.9%) showed multidrug resistance phenotypes to at least three classes of antimicrobials. The multidrug-resistant Shigella spp. were as follows: Shigella flexneri (66.7%), Shigella sonnei (18.5%), and Shigella dysenteriae (3.7%). The highest resistance was to streptomycin (100.0%), then to kanamycin (95.8%), nalidixic acid (95.8%), tetracycline (95.8%), spectinomycin (93.6%), ampicillin (87.5%), and sulfamethoxazole/trimethoprim (87.5%). PCR and DNA sequencing were used to screen and characterize integrons and antibiotic resistance genes. Our results indicated that 11.1% and 74.1% of isolates were positive for class 1 and class 2 integrons, respectively. Beta-lactamase-encoding genes were identified in 77.8% of isolates, and plasmid-mediated quinolone resistance genes were identified in 44.4% of isolates. These data provide useful information to better understand the molecular basis of antimicrobial resistance in Shigella spp. To the best of our knowledge, this is the first report of the molecular characterization of antibiotic resistance in Shigella spp. isolated from food.

  17. The culturable soil antibiotic resistome: a community of multi-drug resistant bacteria.

    Directory of Open Access Journals (Sweden)

    Fiona Walsh

    Full Text Available Understanding the soil bacterial resistome is essential to understanding the evolution and development of antibiotic resistance, and its spread between species and biomes. We have identified and characterized multi-drug resistance (MDR mechanisms in the culturable soil antibiotic resistome and linked the resistance profiles to bacterial species. We isolated 412 antibiotic resistant bacteria from agricultural, urban and pristine soils. All isolates were multi-drug resistant, of which greater than 80% were resistant to 16-23 antibiotics, comprising almost all classes of antibiotic. The mobile resistance genes investigated, (ESBL, bla NDM-1, and plasmid mediated quinolone resistance (PMQR resistance genes were not responsible for the respective resistance phenotypes nor were they present in the extracted soil DNA. Efflux was demonstrated to play an important role in MDR and many resistance phenotypes. Clinically relevant Burkholderia species are intrinsically resistant to ciprofloxacin but the soil Burkholderia species were not intrinsically resistant to ciprofloxacin. Using a phenotypic enzyme assay we identified the antibiotic specific inactivation of trimethoprim in 21 bacteria from different soils. The results of this study identified the importance of the efflux mechanism in the soil resistome and variations between the intrinsic resistance profiles of clinical and soil bacteria of the same family.

  18. Evaluation of [{sup 11}C]laniquidar as a tracer of P-glycoprotein: radiosynthesis and biodistribution in rats

    Energy Technology Data Exchange (ETDEWEB)

    Luurtsema, Gert [Department of Nuclear Medicine and PET Research, VU University Medical Centre, P.O. Box 7057, 1007 MB Amsterdam (Netherlands)], E-mail: g.luurtsema@vumc.nl; Schuit, Robert C.; Klok, Rob P.; Verbeek, Joost; Leysen, Josee E.; Lammertsma, Adriaan A.; Windhorst, Albert D. [Department of Nuclear Medicine and PET Research, VU University Medical Centre, P.O. Box 7057, 1007 MB Amsterdam (Netherlands)

    2009-08-15

    At present, P-glycoprotein (P-gp) function can be studied using positron emission tomography (PET) together with a labelled P-gp substrate such as (R)-[{sup 11}C]verapamil. Such a tracer is, however, less suitable for investigating P-gp (over)expression. Laniquidar is a third-generation P-gp inhibitor, which has been used in clinic trials for modulating multidrug resistance transporters. The purpose of the present study was to develop the radiosynthesis of [{sup 11}C]laniquidar and to assess its suitability as a tracer of P-gp expression. The radiosynthesis of [{sup 11}C]laniquidar was performed by methylation of the carboxylic acid precursor with [{sup 11}C]CH{sub 3}I. The product was purified by HPLC and reformulated over a tC{sub 18} Seppak, yielding a sterile solution of [{sup 11}C]laniquidar in saline. For evaluating [{sup 11}C]laniquidar, rats were injected with 20 MBq [{sup 11}C]laniquidar via a tail vein and sacrificed at 5, 15, 30 and 60 min after injection. Several tissues and distinct brain regions were dissected and counted for radioactivity. In addition, uptake of [{sup 11}C]laniquidar in rats pretreated with cyclosporine A and valspodar (PSC 833) was determined at 30 min after injection. Finally, the metabolic profile of [{sup 11}C]laniquidar in plasma was determined. [{sup 11}C]Laniquidar could be synthesized in moderate yields with high specific activity. Uptake in brain was low, but significantly increased after administration of cyclosporine A. Valspodar did not have any effect on cerebral uptake of [{sup 11}C]laniquidar. In vivo rate of metabolism was relatively low. Further kinetic studies are needed to investigate the antagonistic behaviour of [{sup 11}C]laniquidar at tracer level.

  19. Capreomycin-induced optic neuritis in a case of multidrug resistant pulmonary tuberculosis

    Directory of Open Access Journals (Sweden)

    Magazine Rahul

    2010-01-01

    Full Text Available A patient of multidrug-resistant pulmonary tuberculosis was prescribed an anti-tubercular regimen containing capreomycin. Patient developed optic neuritis 3 months after starting treatment. Investigations did not reveal any specific cause for this ocular condition and on discontinuing capreomycin his vision recovered. We conclude that capreomycin is the cause of reversible optic neuritis in our case.

  20. Distribution and physiology of ABC-Type transporters contributing to multidrug resistance in bacteria

    NARCIS (Netherlands)

    Lubelski, Jacek; Konings, Wil N.; Driessen, Arnold J. M.

    2007-01-01

    Membrane proteins responsible for the active efflux of structurally and functionally unrelated drugs were first characterized in higher eukalyotes. To date, a vast number of transporters contributing to multidrug resistance (MDR transporters) have been reported for a large variety of organisms. Pred

  1. Identification of New Drug Targets in Multi-Drug Resistant Bacterial Infections

    Science.gov (United States)

    2012-10-01

    COVERED 26 September 2011 25 September 2012 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Identification of New Drug Targets in Multi-Drug Resistant...will be necessary for the fragment based screening and subsequent design of new drug lead compounds. To accompany and validate the structural studies

  2. Intestinal Decontamination of Multidrug-resistant Klebsiella pneumoniae After Recurrent Infections in an Immunocompromised Host

    Science.gov (United States)

    Kronman, Matthew P.; Zerr, Danielle M.; Qin, Xuan; Englund, Janet; Cornell, Cathy; Sanders, Jean E.; Myers, Jeffrey; Rayar, Jaipreet; Berry, Jessica E.; Adler, Amanda L.; Weissman, Scott J.

    2014-01-01

    Multidrug-resistant (MDR) Enterobacteriaceae infections are associated with increased morbidity. We describe a 20-year-old hematopoietic cell transplantation recipient with recurrent MDR Klebsiella pneumoniae infection, prolonged intestinal colonization, and subsequent intestinal decontamination. Further study should evaluate stool surveillance, molecular typing, and fecal microbiota transplantation for patients with intestinal MDR Enterobacteriaceae carriage. PMID:25041704

  3. Antibacterial activities of ethanol extracts of Philippine medicinal plants against multidrug-resistant bacteria

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    Demetrio L. Valle Jr.

    2015-07-01

    Conclusions: P. betle had the greatest potential value against both Gram-negative and Gram-positive multidrug-resistant bacteria. Favorable antagonistic activities were also exhibited by the ethanol extracts of Psidium guajava, Phyllanthus niruri and Ehretia microphylla.

  4. Recycling antibiotics into GUMBOS: A new combination strategy to combat multi-drug resistant bacteria

    Science.gov (United States)

    The emergence of multi-drug resistant bacteria, coupled with the lack of new antibiotics in development, is fast evolving into a global crisis. New strategies utilizing existing antibacterial agents are urgently needed. We propose one such strategy in which four outmoded ß-lactam antibiotics (amp...

  5. Isolation and characterization of antimicrobial compounds in plant extracts against multidrug-resistant Acinetobacter baumannii.

    Directory of Open Access Journals (Sweden)

    Yoko Miyasaki

    Full Text Available The number of fully active antibiotic options that treat nosocomial infections due to multidrug-resistant Acinetobacter baumannii (A. baumannii is extremely limited. Magnolia officinalis, Mahonia bealei, Rabdosia rubescens, Rosa rugosa, Rubus chingii, Scutellaria baicalensis, and Terminalia chebula plant extracts were previously shown to have growth inhibitory activity against a multidrug-resistant clinical strain of A. baumannii. In this study, the compounds responsible for their antimicrobial activity were identified by fractionating each plant extract using high performance liquid chromatography, and determining the antimicrobial activity of each fraction against A. baumannii. The chemical structures of the fractions inhibiting >40% of the bacterial growth were elucidated by liquid chromatography/mass spectrometry analysis and nuclear magnetic resonance spectroscopy. The six most active compounds were identified as: ellagic acid in Rosa rugosa; norwogonin in Scutellaria baicalensis; and chebulagic acid, chebulinic acid, corilagin, and terchebulin in Terminalia chebula. The most potent compound was identified as norwogonin with a minimum inhibitory concentration of 128 µg/mL, and minimum bactericidal concentration of 256 µg/mL against clinically relevant strains of A. baumannii. Combination studies of norwogonin with ten anti-Gram negative bacterial agents demonstrated that norwogonin did not enhance the antimicrobial activity of the synthetic antibiotics chosen for this study. In conclusion, of all identified antimicrobial compounds, norwogonin was the most potent against multidrug-resistant A. baumannii strains. Further studies are warranted to ascertain the prophylactic and therapeutic potential of norwogonin for infections due to multidrug-resistant A. baumannii.

  6. Characterization of putative multidrug resistance transporters of the major facilitator-superfamily expressed in Salmonella Typhi

    DEFF Research Database (Denmark)

    Shaheen, Aqsa; Ismat, Fouzia; Iqbal, Mazhar

    2015-01-01

    of this study was to gain insight into the substrate specificity of previously uncharacterized transporters of Salmonella Typhi to identify their role in the development of multidrug resistance. S. Typhi genes encoding putative members of the major facilitator superfamily were cloned and expressed in the drug...

  7. Novel mechanism of bacteriocin secretion and immunity carried out by lactococcal multidrug resistance proteins

    NARCIS (Netherlands)

    Gajic, O; Buist, G; Kojic, M; Topisirovic, L; Kuipers, OP; Kok, J

    2003-01-01

    A natural isolate of Lactococcus lactis was shown to produce two narrow spectrum class II bacteriocins, designated LsbA and LsbB. The cognate genes are located on a 5.6-kb plasmid within a gene cluster specifying LmrB, an ATP-binding cassette-type multidrug resistance transporter protein. LsbA is a

  8. Expression of multidrug resistance-associated proteins predicts prognosis in childhood and adult acute lymphoblastic leukemia

    NARCIS (Netherlands)

    Plasschaert, SLA; de Bont, ESJM; Boezen, M; vander Kolk, DM; Daenen, SMJG; Faber, KN; Kamps, WA; de Vries, EGE; Vellenga, E

    2005-01-01

    PURPOSE: Patients with acute lymphoblastic leukemia (ALL) are treated with a variety of chemotherapeutic drugs, which can be transported by six multidrug resistance-associated proteins (MRP). These MRPs have strongly overlapping functional activities. The aim of this study was to investigate the exp

  9. Evaluation of macrolides for possible use against multidrug-resistant Mycobacterium tuberculosis

    NARCIS (Netherlands)

    van der Paardt, Anne-Fleur; Wilffert, Bob; Akkerman, Onno W.; de Lange, Wiel C. M.; van Soolingen, Dick; Sinha, Bhanu; van der Werf, Tjip S.; Kosterink, Jos G. W.; Alffenaar, Jan-Willem C.

    2015-01-01

    Multidrug-resistant tuberculosis (MDR-TB) is a major global health problem. The loss of susceptibility to an increasing number of drugs behoves us to consider the evaluation of non-traditional anti-tuberculosis drugs. Clarithromycin, a macrolide antibiotic, is defined as a group 5 anti-tuberculosis

  10. Individualized treatment of multidrug-resistant tuberculosis using therapeutic drug monitoring

    NARCIS (Netherlands)

    Bolhuis, Mathieu S; Akkerman, Onno W; Sturkenboom, Marieke G G; de Lange, Wiel C M; van der Werf, Tjip S; Alffenaar, Jan-Willem C

    2016-01-01

    OBJECTIVE/BACKGROUND: Globally, approximately 50% of patients with multidrug-resistant tuberculosis (MDR-TB) experience treatment failure. MDR-TB treatment is hindered by adverse events, toxicity of the second-line anti-TB drugs, logistics and costs, especially in low-income countries, and problems

  11. A cohort study on the outcome of multidrug-resistant tuberculosis in elderly patients

    Institute of Scientific and Technical Information of China (English)

    郝晓晖

    2014-01-01

    Objective To investigate the clinical curative effect and outcomes of multidrug-resistant tuberculosis(MDRTB)in elderly patients.Methods Fifty-nine elderly patients with MDR-TB were enrolled from Shanghai Pulmonary Hospital from January 2007 to January 2010,and80 younger patients with MDR-TB during the same period served as the control group.Clinical characteristics,out-

  12. Targeting multidrug-resistant tuberculosis (MDR-TB) by therapeutic vaccines

    NARCIS (Netherlands)

    Prabowo, Satria A.; Groeschel, Matthias I.; Schmidt, Ed D. L.; Skrahina, Alena; Mihaescu, Traian; Hasturk, Serap; Mitrofanov, Rotislav; Pimkina, Edita; Visontai, Ildik; de Jong, Bouke; Stanford, John L.; Cardona, Pere-Joan; Kaufmann, Stefan H. E.; van der Werf, Tjipke

    2013-01-01

    Tuberculosis (TB) has scourged humankind for millennia, and latent infection affects nearly one-third of today's world population. The emergence of multidrug-resistant (MDR)-TB is a major global threat and reflects treatment failure of drug-sensitive disease. MDR-TB management is a burden for patien

  13. Potential antimicrobial agents for the treatment of multidrug-resistant tuberculosis

    NARCIS (Netherlands)

    Alsaad, Noor; Wilffert, Bob; van Altena, Richard; de Lange, Wiel C. M.; van der Werf, Tjip S.; Kosterink, Jos G. W.; Alffenaar, Jan-Willem C.

    2014-01-01

    Treatment of multidrug-resistant (MDR) tuberculosis (TB) is challenging because of the high toxicity of second-line drugs and the longer treatment duration than for drug-susceptible TB patients. In order to speed up novel treatment for MDR-TB, we suggest considering expanding the indications of alre

  14. Multidrug-resistant tuberculosis, People's Republic of China, 2007-2009.

    NARCIS (Netherlands)

    He, G.X.; Wang, H.Y.; Borgdorff, M.W.; Soolingen, D. van; Werf, M.J. van der; Liu, Z.M.; Li, X.Z.; Guo, H.; Zhao, Y.L.; Varma, J.K.; Tostado, C.P.; Hof, S. van den

    2011-01-01

    We conducted a case-control study to investigate risk factors for multidrug-resistant tuberculosis (MDR TB) in the People's Republic of China. Genotyping analysis was used to estimate the percentage of cases from recent transmission among 100 MDR TB case-patients hospitalized during April 2007-July

  15. Beauvericin counteracted multi-drug resistant Candida albicans by blocking ABC transporters

    DEFF Research Database (Denmark)

    Tong, Yaojun; Liu, Mei; Zhang, Yu

    2016-01-01

    screening and whole-cell based mechanism study, identified a natural product, beauvericin (BEA) as a drug efflux pump modulator, which can reverse the multi-drug resistant phenotype of Candida albicans by specifically blocking the ATP-binding cassette (ABC) transporters; meantime, BEA alone has fungicidal...

  16. What do proton motive force driven multidrug resistance transporters have in common?

    NARCIS (Netherlands)

    Mazurkiewicz, P.; Driessen, A.J.M.; Konings, W.N

    2005-01-01

    The extensive progress of genome sequencing projects in recent years has demonstrated that multidrug resistance (MDR) transporters are widely spread among all domains of life. This indicates that they play crucial roles in the survival of organisms. Moreover, antibiotic and chemotherapeutic treatmen

  17. Multidrug resistant Acinetobacter baumannii reaches a new frontier: prosthetic hip joint infection.

    Science.gov (United States)

    Hischebeth, G T R; Wimmer, M D; Molitor, E; Seifert, H; Gravius, S; Bekeredjian-Ding, I

    2015-02-01

    Acinetobacter baumannii is an emerging nosocomial pathogen primarily in countries with a high prevalence of multidrug resistance. Here we report the detection of a bla OXA23 carbapenemase-producing A. baumannii strain in a German patient with prosthetic hip joint infection following several hip joint surgeries but no history of foreign travel.

  18. [Reversing effects of emodin on multidrug resistance in resistant HL-60/ADR cells].

    Science.gov (United States)

    Chen, Ying-Yu; Li, Jing; Hu, Jian-Da; Zheng, Jing; Zheng, Zhi-Hong; Zhu, Liang-Fang; Chen, Xin-Ji; Lin, Zhen-Xing

    2013-12-01

    This study was aimed to investigate the reversing effects of emodin on multidrug resistance (MDR) in resistant HL-60/ADR cells, and to explore the underlying mechanisms. The MTT assay was used to assess the chemoresistance of HL-60/ADR cells to emodin and 8 chemotherapeutic agents commonly used in clinic. The reversal effects of emodin on MDR of HL-60/ADR cells were also evaluated by MTT method. DNA ploidy analysis and DNA Ladder assay were used to detect apoptosis-induced effects on HL-60/ADR cells via the adriamycin (ADR) and emodin combination. The expression changes of the drug resistance-associated genes and proteins were detected by RT-PCR and Western Blot respectively. The intracellular accumulation and subcellular distribution of ADR and DNR were measured by flow cytometry and confocal laser scanning microscopy. The results showed that emodin inhibited HL-60/ADR cell proliferation with an average IC50 value of 24.09 ± 1.72 µmol/L, which was similar to that of the parental HL-60 cells (average IC50 = 23.18 ± 0.87 µmol/L). HL-60/ADR cells were resistant to a variety of chemotherapeutic agents, such as ADR, DNR, VP16, VCR,Ara-C, HHT, MTZ and THP. The reversal multiple were between 1.58 and 4.12 after the treatment with low concentration of emodin combined with the above mentioned different agents. The combination of ADR with emodin showed the best reversal effects, and the typical hypodiploid peak (apoptotic peak) and DNA ladder could be detected after the co-treatment.In addition, emodin down-regulated the mRNA and protein expression levels of MRP1, TOPOIIβ, GST π and BCL-2. Furthermore, the addition of emodin enhanced ADR and DNR intracellular accumulation and subcellular distribution in HL-60/ADR cells in dose-dependent manner. It is concluded that the emodin shows reversing effects on the multidrug resistant HL-60/ADR cells, possibly via decreasing the expression levels of drug resistance-associated genes, increasing the intracellular accumulation of

  19. Characterization of integrons and resistance genes in multidrug-resistant Salmonella enterica isolated from meat and dairy products in Egypt.

    Science.gov (United States)

    Ahmed, Ashraf M; Shimamoto, Toshi; Shimamoto, Tadashi

    2014-10-17

    Foodborne pathogens are a leading cause of illness and death, especially in developing countries. The problem is exacerbated if bacteria attain multidrug resistance. Little is currently known about the extent of antibiotic resistance in foodborne pathogens and the molecular mechanisms underlying this resistance in Africa. Therefore, the current study was carried out to characterize, at the molecular level, the mechanism of multidrug resistance in Salmonella enterica isolated from 1600 food samples (800 meat products and 800 dairy products) collected from different street venders, butchers, retail markets and slaughterhouses in Egypt. Forty-seven out of 69 isolates (68.1%) showed multidrug resistance phenotypes to at least three classes of antimicrobials. The incidence of multidrug-resistant isolates was higher in meat products (37, 69.8%) than in dairy products (10, 62.5%). The multidrug-resistant serovars included, S. enterica serovar Typhimurium (24 isolates, 34.8%), S. enterica serovar Enteritidis, (15 isolates, 21.8%), S. enterica serovar Infantis (7 isolates, 10.1%) and S. enterica non-typable serovar (1 isolate, 1.4%). The highest resistance was to ampicillin (95.7%), then to kanamycin (93.6%), spectinomycin (93.6%), streptomycin (91.5%) and sulfamethoxazole/trimethoprim (91.5%). PCR and DNA sequencing were used to screen and characterize integrons and antibiotic resistance genes and 39.1% and 8.7% of isolates were positive for class 1 and class 2 integrons, respectively. β-lactamase-encoding genes were identified in 75.4% of isolates and plasmid-mediated quinolone resistance genes were identified in 27.5% of isolates. Finally, the florphenicol resistance gene, floR, was identified in 18.8% of isolates. PCR screening identified S. enterica serovar Typhimurium DT104 in both meat and dairy products. This is the first study to report many of these resistance genes in dairy products. This study highlights the high incidence of multidrug-resistant S. enterica in

  20. FG020326-1oaded nanoparticle with PEG and PDLLA improved pharma-codynamics of reversing multidrug resistance in vitro and in vivo

    Institute of Scientific and Technical Information of China (English)

    Wen-jing DENG; Xiao-qiang YANG; Yong-ju LIANG; Li-ming CHEN; Yan-yan YAN; Xin-tao SHUAI; Li-wu FU

    2007-01-01

    Aim: FG020326, a novel imidazole derivative, is a potent multidrug-resistance (MDR) modulator in vitro and in vivo. However, FG020326 is insoluble. PEDLLA-FG020326 is a FG020326-loaded nanoparticle formed with diblock eopolymers of poly (ethylene glycol)-bloek-poly (D,L-lactic acid) (PEG:PDLLA, PEDLLA) that can solubilize FG020326. This work was intended to evaluate the pharmacody-namics of PEDLLA-FG020326 on reversing MDR in vitro and in vivo.Methods: Cytotoxicity was determined by tetrazolium assay. The intraceUular accumulation and efflux of doxorubicin (Dox) were detected by fluorescence spectrophotometry.The function of P-glycoprotein was examined by Rhodamine 123 (Rh 123) accumu-lation detected by flow cytometry. The KBv200 cell xenograft model was estab-lished to investigate the effect of PEDLLA-FG020326 on reversing MDR in vivo.Results: PEDLLA-FG020326 and FG020326 exhibited 56.4- and 35.9-fold activity in reversing KBv200 cells to vincristine (VCR) resistance, respectively and 14.98-and 7.64-fold to Dox resistance, respectively. PEDLLA-FG020326 was much stron-ger than FG020326, resulting in the increase of Dox and Rh123 accumulation and the decrease of intracellular Dox extrusion in KBv200 cells. Importantly, PEDLLA-FG020326 exhibited more powerful activity than FG020326 in enhancing the effect of VCR against KBv200 cell xenografts in nude mice, but did not appear more toxic.Conclusion: The pharmacodynamics of FG020326 was improved by incorporating it into a micellar nanoparticle formed with PEG-block-PDLLA copolymers.

  1. Multidrug resistant bacteria in companion animals: impact on animal health and zoonotic aspects

    DEFF Research Database (Denmark)

    Damborg, Peter Panduro

    The role of companion animals as a source of antibiotic resistant bacteria has historically been given little emphasis when compared with that of food animals. However, various resistant bacteria may cause serious treatment problems in companion animal medicine. Some of the most important multidrug......-resistant bacteria include methicillin-resistant Staphylococcus pseudintermedius (MRSP), methicillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae. These bacteria will be described with focus on their prevalence across Europe, their impact on animal...

  2. Development of Classification Models for Identifying “True” P-glycoprotein (P-gp Inhibitors Through Inhibition, ATPase Activation and Monolayer Efflux Assays

    Directory of Open Access Journals (Sweden)

    Anna Maria Bianucci

    2012-06-01

    Full Text Available P-glycoprotein (P-gp is an efflux pump involved in the protection of tissues of several organs by influencing xenobiotic disposition. P-gp plays a key role in multidrug resistance and in the progression of many neurodegenerative diseases. The development of new and more effective therapeutics targeting P-gp thus represents an intriguing challenge in drug discovery. P-gp inhibition may be considered as a valid approach to improve drug bioavailability as well as to overcome drug resistance to many kinds of tumours characterized by the over-expression of this protein. This study aims to develop classification models from a unique dataset of 59 compounds for which there were homogeneous experimental data on P-gp inhibition, ATPase activation and monolayer efflux. For each experiment, the dataset was split into a training and a test set comprising 39 and 20 molecules, respectively. Rational splitting was accomplished using a sphere-exclusion type algorithm. After a two-step (internal/external validation, the best-performing classification models were used in a consensus predicting task for the identification of compounds named as “true” P-gp inhibitors, i.e., molecules able to inhibit P-gp without being effluxed by P-gp itself and simultaneously unable to activate the ATPase function.

  3. Evaluation of multidrug resistance-1 gene C>T polymorphism frequency in patients with asthma

    Directory of Open Access Journals (Sweden)

    Ümran Toru

    2015-10-01

    Full Text Available OBJECTIVES:Asthma is a chronic inflammatory lung disease characterized by bronchial hyperresponsiveness and airflow obstruction. Genetic and oxidative stress factors, in addition to pulmonary and systemic inflammatory processes, play a pivotal role in the pathogenesis of asthma. The products of the multidrug resistance-1 gene protect lung tissue from oxidative stress. Here, we aimed to evaluate the association between the multidrug resistance-1 gene C>T polymorphism and asthma with regard to oxidative stress-related parameters of asthmatic patients.METHODS:Forty-five patients with asthma and 27 healthy age-matched controls were included in this study. Blood samples were collected in tubes with ethylenediaminetetraacetic acid. DNA was extracted from the blood samples. The multidrug resistance-1 gene polymorphism was detected by polymerase chain reaction and a subsequent enzyme digestion technique. The serum levels of total oxidant status and total antioxidant status were determined by the colorimetric measurement method.RESULTS:The heterozygous polymorphic genotype was the most frequent in both groups. A significant difference in the multidrug resistance-1 genotype frequencies between groups indicated an association of asthma with the TT genotype. A significant difference between groups was found for wild type homozygous participants and carriers of polymorphic allele participants. The frequency of the T allele was significantly higher in asthmatic patients. The increase in the oxidative stress index parameter was significant in the asthma group compared with the control group.CONCLUSIONS:The multidrug resistance-1 gene C/T polymorphism may be an underlying genetic risk factor for the development of asthma via oxidant-antioxidant imbalance, leading to increased oxidative stress.

  4. Multidrug and heavy metal-resistant Raoultella planticola isolated from surface water.

    Science.gov (United States)

    Koc, Serkan; Kabatas, Burak; Icgen, Bulent

    2013-08-01

    A surface water isolate of Raoultella sp. having both multidrug- and multimetal-resistant ability was isolated and identified as Raoultella planticola. R. planticola displayed resistance to 15 drugs like ampicillin, amoxicillin/clavulanic acid, aztreonam, erythromycin, imipenem, oxacillin, pefloxacin, penicillin, piperacillin, piperacillin/tazobactam, rifampin, sulbactam/cefoperazone, ticarsillin, ticarsillin/clavulanic acid, vancomycin, and to 11 heavy metals like aluminum, barium, copper, iron, lead, lithium, manganese, nickel, silver, strontium, and tin. The multidrug and multi-metal-resistant R. planticola may remain present in the environment for a long time. Due to a possible health risk of these pathogenic bacteria, a need exists for an accurate assessment of their acquired resistance to multiple drugs and metals.

  5. Antimicrobial metallopolymers and their bioconjugates with conventional antibiotics against multidrug-resistant bacteria.

    Science.gov (United States)

    Zhang, Jiuyang; Chen, Yung Pin; Miller, Kristen P; Ganewatta, Mitra S; Bam, Marpe; Yan, Yi; Nagarkatti, Mitzi; Decho, Alan W; Tang, Chuanbing

    2014-04-02

    Bacteria are now becoming more resistant to most conventional antibiotics. Methicillin-resistant Staphylococcus aureus (MRSA), a complex of multidrug-resistant Gram-positive bacterial strains, has proven especially problematic in both hospital and community settings by deactivating conventional β-lactam antibiotics, including penicillins, cephalosporins, and carbapenems, through various mechanisms, resulting in increased mortality rates and hospitalization costs. Here we introduce a class of charged metallopolymers that exhibit synergistic effects against MRSA by efficiently inhibiting activity of β-lactamase and effectively lysing bacterial cells. Various conventional β-lactam antibiotics, including penicillin-G, amoxicillin, ampicillin, and cefazolin, are protected from β-lactamase hydrolysis via the formation of unique ion-pairs between their carboxylate anions and cationic cobaltocenium moieties. These discoveries could provide a new pathway for designing macromolecular scaffolds to regenerate vitality of conventional antibiotics to kill multidrug-resistant bacteria and superbugs.

  6. REVERSAL EFFECTS OF MIFEPRISTONE ON MULTIDRUG RESISTANCE(MDR) IN DRUG-RESISTANT BREAST CANCER CELL LINE MCF7/ADR IN VITRO AND IN VIVO

    Institute of Scientific and Technical Information of China (English)

    李大强; 潘丽华; 邵志敏

    2004-01-01

    Objective: To explore the reversal effect of mifepristone on multidrug resistance (MDR) in drug-resistant human breast cancer cell line MCF7/ADR and its mechanisms. Methods: Expression of MDR1 and MDR-associated protein(MRP) mRNA in MCF7/ADR cells was detected using reverse transcription- polymerase chain reaction(RT-PCR). Western blotting was used to assay the protein levels of P-glycoprotein (P-gp) and MRP. Intracellular rhodamine 123 retention and [3H]vincristine (VCR) accumulation were measured by flow cytometry and liquid scintillation counter, respectively. MTT reduction assay was used to determine the sensitivity of cells to the anticancer agent, adriamycin (ADR). Additionally, a MCF7/ADR cell xenograft model was established to assess the reversal effect of mifeprisone on MDR in MCF7/ADR cells in vivo. Results: Miferpristone dose-dependently down- regulated the expression of MDR1 and MRP mRNA in MCF7/ADR cells, accompanied by a significant decrease in the protein levels of P-gp and MRP. After exposure to 5, 10, and 20 μmol/L mifepristone, MCF7/ADR cells showed a 3.87-, 5.81-, and 7.40-fold increase in the accumulation of intracellular VCR(a known substrate of MRP), and a 2.14-, 4.39-, and 5.53-fold increase in the retention of intracellular rhodamine 123(an indicator of P-gp function), respectively. MTT analysis showed that the sensitivity of MCF7/ADR cells to ADR was enhanced by 7.23-, 13.62-, and 20.96-fold after incubation with mifepristone as above-mentioned doses for 96 h. In vivo, mifepristone effectively restored the chemosensitivity of MCF7/ADR cells to ADR. After 8 weeks of administration with ADR(2 mg·kg-1·d-1) alone or in combination with mifepristone(50 mg·kg-1·d-1), the growth inhibitory rate of xenografted tumors in nude mice was 8.08% and 37.25%, respectively. Conclusion: Mifepristone exerts potent reversal effects on MDR in MCF7/ADR cells in vitro and in vivo through down- regulation of MDR1/P-gp and MRP expression and inhibition of P

  7. Cloning and characterization of the rat multidrug resistance-associated protein 1

    OpenAIRE

    Yang, Ziping; Li, Cheryl S. W.; Shen, Danny D.; Ho, Rodney J. Y.

    2002-01-01

    Multidrug resistance-associated protein 1 (MRP1) was originally shown to confer resistance of human tumor cells to a broad range of natural product anticancer drugs. MRP1 has also been shown to mediate efflux transport of glutathione and glucuronide conjugates of drugs and endogenous substrates. An ortholog of MRP1 in the mouse has been cloned and characterized. Significant functional differences between murine and human MRP1 have been noted. Since drug disposition and pharmacology studies of...

  8. In vitro antimicrobial activity of five essential oils on multidrug resistant Gram-negative clinical isolates

    OpenAIRE

    Sakkas, Hercules; Gousia, Panagiota; Economou, Vangelis; Sakkas, Vassilios; Petsios, Stefanos; Papadopoulou, Chrissanthy

    2016-01-01

    Aim/Background: The emergence of drug-resistant pathogens has drawn attention on medicinal plants for potential antimicrobial properties. The objective of the present study was the investigation of the antimicrobial activity of five plant essential oils on multidrug resistant Gram-negative bacteria. Materials and Methods: Basil, chamomile blue, origanum, thyme, and tea tree oil were tested against clinical isolates of Acinetobacter baumannii (n = 6), Escherichia coli (n = 4), Klebsiella pneum...

  9. Novel Bis-Indole Agents Active Against Multidrug-Resistant Acinetobacter baumannii

    Science.gov (United States)

    Jacobs, Michael R.; Bajaksouzian, Saralee; Good, Caryn E.; Butler, Michelle M.; Williams, John D.; Peet, Norton P.; Bowlin, Terry L.; Endimiani, Andrea; Bonomo, Robert A

    2013-01-01

    The in vitro activity of five novel Microbiotix bis-indole agents (MBXs) against 30 multidrug-resistant (MDR) A. baumannii (including 18 resistant to carbapenems) was evaluated. Overall, MIC90s ranged from 1-8 μg/ml, whereas those for imipenem were > 64 μg/ml. MBX 1196 was the most potent (MIC90 1 μg/ml). MBXs are compounds that are highly effective against MDR A. baumannii. PMID:21146724

  10. Whole genome sequencing of emerging multidrug resistant Candida auris isolates in India demonstrates low genetic variation

    OpenAIRE

    2016-01-01

    Candida auris is an emerging multidrug resistant yeast that causes nosocomial fungaemia and deep-seated infections. Notably, the emergence of this yeast is alarming as it exhibits resistance to azoles, amphotericin B and caspofungin, which may lead to clinical failure in patients. The multigene phylogeny and amplified fragment length polymorphism typing methods report the C. auris population as clonal. Here, using whole genome sequencing analysis, we decipher for the first time that C. auris ...

  11. The burden of transmitted multi-drug resistance among epidemics of tuberculosis: A transmission model

    OpenAIRE

    Emily A Kendall; Fofana, Mariam O.; Dowdy, David W.

    2015-01-01

    Background Multidrug-resistant tuberculosis (MDR-TB) can be acquired through de novo mutation during TB treatment or through transmission from other individuals with active MDR-TB. Understanding the balance between these two mechanisms is essential when allocating resources for MDR-TB. Methods We constructed a dynamic transmission model of an MDR-TB epidemic, allowing for both treatment-related acquisition and person-to-person transmission of resistance. We used national TB notification data ...

  12. Multidrug-resistant Acinetobacter Infection Mortality Rate and Length of Hospitalization

    OpenAIRE

    Sunenshine, Rebecca H.; Wright, Marc-Oliver; Maragakis, Lisa L.; Harris, Anthony D.; Song, Xiaoyan; Hebden, Joan; Cosgrove, Sara E.; Anderson, Ashley; Carnell, Jennifer; Jernigan, Daniel B.; Kleinbaum, David G.; Perl, Trish M.; Standiford, Harold C.; Srinivasan, Arjun

    2007-01-01

    Acinetobacter infections have increased and gained attention because of the organism’s prolonged environmental survival and propensity to develop antimicrobial drug resistance. The effect of multidrug-resistant (MDR) Acinetobacter infection on clinical outcomes has not been reported. A retrospective, matched cohort investigation was performed at 2 Baltimore hospitals to examine outcomes of patients with MDR Acinetobacter infection compared with patients with susceptible Acinetobacter infectio...

  13. Anthelmintic Avermectins Kill Mycobacterium tuberculosis, Including Multidrug-Resistant Clinical Strains

    OpenAIRE

    Lim, Leah E.; Vilchèze, Catherine; Ng, Carol; Jacobs, William R.; Ramón-García, Santiago; Thompson, Charles J

    2013-01-01

    Avermectins are a family of macrolides known for their anthelmintic activities and traditionally believed to be inactive against all bacteria. Here we report that members of the family, ivermectin, selamectin, and moxidectin, are bactericidal against mycobacterial species, including multidrug-resistant and extensively drug-resistant clinical strains of Mycobacterium tuberculosis. Avermectins are approved for clinical and veterinary uses and have documented pharmacokinetic and safety profiles....

  14. Bactericidal Efficacy of Allium sativum (garlic Against Multidrug Resistant Vibrio cholerae O1 Epidemic Strains

    Directory of Open Access Journals (Sweden)

    Pramod Kumar

    2016-09-01

    Full Text Available In recent years, emerging trend of antibiotic resistance in Vibrio cholerae associated with cholera epidemics is a matter of serious concern for the management of the disease. Indiscriminate use of antibiotics generally results in selection of antibiotic resistant strains. Introduction of newer antibiotics is a challenging task for the researchers as bacteria soon attain resistance. Therefore, identifying natural compounds of medicinal importance for control of cholera would be the best alternative. Garlic (Allium sativum was recognised for many centuries in early Chinese, Egyptian and Indian civilisations as an herbal or traditional medicine. In present study, garlic was selected for screening of antimicrobial efficacy against V. cholerae. A total of 55 V. cholerae strains isolated from various outbreaks/epidemics were subjected to antimicrobial testing as per CLSI, USA 2010 guidelines. Antimicrobial screening of garlic extract was performed against all the multidrug resistant strains of V. cholerae. The garlic extracts showed antibacterial activity against all the V. cholerae strains tested, irrespective of their origin, multidrug resistance and virulence. Antibacterial efficacy of garlic on V. cholerae was also evident from in vivo study on sealed adult mice model. Thus, the Garlic extract harnesses the potential to control infection of multidrug resistant V. cholerae, especially in outbreak like situations in remote and under developed areas where drug supply itself is a challenge

  15. Intraventricular ciprofloxacin usage in treatment of multidrug-resistant central nervous system infections: report of four cases

    Directory of Open Access Journals (Sweden)

    Ayse Karaaslan

    2014-12-01

    Full Text Available In recent years, multidrug-resistant microorganisms appear as important nosocomial pathogens which treatment is quite difficult. As sufficient drug levels could not be achieved in cerebrospinal fluid during intravenous antibiotic therapy for central nervous system infections and due to multidrug-resistance treatment alternatives are limited. In this study, four cases of central nervous system infections due to multidrug-resistant microorganisms who were successfully treated with removal of the devices and intraventricular ciprofloxacin are presented. In conclusion, intraventricular ciprofloxacin can be used for treatment of central nervous system infections if the causative microorganism is sensitive to the drug and no other alternative therapy is available.

  16. Transmission of extensively drug-resistant and multidrug resistant Mycobacterium tuberculosis in families identified by genotyping

    Institute of Scientific and Technical Information of China (English)

    YAN Li-ping; QIN Lian-hua; ZHANG Qing; SUN Hua; HAN Min; XIAO He-ping

    2013-01-01

    Background Diagnosis and appropriate treatment of multidrug-resistant tuberculosis (MDR-TB) remain major challenges.We sought to elucidate that persons who share a household with drug resistance tuberculosis patients are at high risk for primary drug resistance tuberculosis and how to prevent these outbreaks.Methods We used 12-locus mycobacterial interspersed repetitive unit and 7-locus variable-number tandem repeat to identify household transmission of extensively drug resistant and multiple drug resistant Mycobacterium tuberculosis in three families admitted in Shanghai Pulmonary Hospital affiliated with Tongji University.Drug susceptibility tests were done by the modified proportion method in the MGIT 960 system in the same time.Clinical data were also obtained from the subjects' medical records.Results All of the six strains were defined as Beijing genotype by the deletion-targeted multiplex PCR (DTM-PCR) identification on the genomic deletion RD105.Strains from family-1 had the same minisatellite interspersed repetitive unit (MIRU) pattem (232225172531) and the same MIRU pattern (3677235).Strains from family-2 had the same MIRU pattern (2212261553323) and the same MIRU pattern (3685134).Strains from family-3 did not have the same MIRU pattern and they differed at only one locus (223326173533,223325173533),and did not have the same VNTR pattern with two locus differed (3667233,3677234).Conclusions Household transmission exists in the three families.A clear chain of tuberculosis transmission within family exists.Tuberculosis susceptibility should be considered when there is more than one tuberculosis patients in a family.Household tuberculosis transmission could be prevented with adequate treatment of source patients.

  17. EFFECTS OF IN VIVO GENE TRANSDUCTION OF ANTI-MDR1 RIBOZYME IN COMBINATION WITH CHEMOTHERAPY ON