WorldWideScience
1

Interaction of tamoxifen with the multidrug resistance P-glycoprotein.  

OpenAIRE

Tamoxifen is an anti-oestrogen which is currently being assessed as a prophylactic for women at high risk of breast cancer. Taxoxifen has also been shown to reverse multidrug resistance in P-glycoprotein (P-gp)-expressing cells, although the mechanism of action is unknown. In this study we demonstrate that tamoxifen interacts directly with P-gp. Plasma membranes from P-gp-expressing cells bound [3H]tamoxifen in a specific and saturable fashion. A 180 kDa membrane protein in these membranes, l...

Callaghan, R; Higgins, C. F.

1995-01-01

2

Multidrug resistance gene (P-glycoprotein) expression in the human fetus.  

OpenAIRE

P-glycoprotein, a transmembrane protein associated with multidrug resistance in cancer cells, is also expressed in normal tissues. To get more insight into the physiologic role of mdr1/P-glycoprotein, we investigated its expression in human fetal tissues after 7 to 38 weeks of gestation by an immunohistochemical technique, using three different monoclonal antibodies, and by a sensitive RNAse protection assay. Expression of mdr1-mRNA could already be demonstrated in the embryonal phase of huma...

Kalken, C.; Giaccone, G.; Valk, P.; Kuiper, C. M.; Hadisaputro, M. M.; Bosma, S. A.; Scheper, R. J.; Meijer, C. J.; Pinedo, H. M.

1992-01-01

3

Kuguacin J isolated from Momordica charantia leaves inhibits P-glycoprotein (ABCB1)-mediated multidrug resistance  

OpenAIRE

Multidrug-resistance (MDR), a phenomenon in which cancer cells exhibit simultaneous resistance to chemically unrelated drugs, is a major factor in the failure of chemotherapy in cancer patients. Resistance to chemotherapy has been correlated to the overexpression of ABC drug transporters including P-glycoprotein (P-gp) that actively efflux chemotherapeutic drugs from cancer cells. Our previous study showed that bitter melon (Momordica charantia) leaf extract (BMLE) was able to reverse the MDR...

Pitchakarn, Pornsiri; Ohnuma, Shinobu; Pintha, Komsak; Pompimon, Wilart; Ambudkar, Suresh V.; Limtrakul, Pornngarm

2011-01-01

4

Photoaffinity labeling of the multidrug-resistance-related P-glycoprotein with photoactive analogs of verapamil  

International Nuclear Information System (INIS)

Verapamil, a phenylalkylamine calcium channel blocker, has been shown to reverse multidrug resistance in tumor cells, possibly by increasing drug retention through interaction with an outward drug transporter of the resistant cells. In this study two photoactive radioactive analogs of verapamil, N-(p-azido[3,5-3H]benzoyl)aminomethyl verapamil and N-(p-azido[3-125I]salicyl)aminomethyl verapamil, were synthesized and used to identify the possible biochemical target(s) for verapamil in multidrug-resistance DC-3F/VCRd-5L Chinese hamster lung cells selected for resistance to vincristine. The results show that a specifically labeled 150- to 180-kDa membrane protein in resistant cells was immunoprecipitated with a monoclonal antibody specific for P-glycoprotein. Phenylalkylamine binding specificity was established by competitive blocking of specific photolabeling with the nonradioactive photoactive analogs as well as with verapamil. Photoaffinity labeling was also inhibited by 50 ?M concentrations of the calcium channel blockers nimodipine, nifedipine, nicardipine, azidopine, bepridil, and diltiazem and partially by prenylamine. Moreover, P-glycoprotein labeling was inhibited in a dose-dependent manner by vinblastine with half-maximal inhibition at 0.2 ?M compared to that by verapamil at 8 ?M. These data provide direct evidence that P-glycoprotein has broad drug recognition capacity and that it serves as a molecular target for calcium channel blockerular target for calcium channel blocker action in reversing multidrug resistance

5

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

OpenAIRE

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...

Li Yan; Peng Chun-Wei; Hu Wen-Qing

2009-01-01

6

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

Directory of Open Access Journals (Sweden)

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.

C.G. Machado

2003-12-01

7

Most drugs that reverse multidrug resistance also inhibit photoaffinity labeling of P-glycoprotein by a vinblastine analog  

International Nuclear Information System (INIS)

Multidrug-resistant human KB carcinoma cells express a 170,000-dalton membrane glycoprotein (P-glycoprotein) that can be photoaffinity labeled with the vinblastine analog N-(p-azido-[3-125I]salicyl]-N'-(beta-aminoethyl)vindesine. Several agents that suppress the multidrug-resistant phenotype, including N-solanesyl-N,N'-bis(3,4-dimethylbenzyl)ethylenediamine, cepharanthine, quinidine, and reserpine, were found to inhibit photolabeling of P-glycoprotein at doses comparable to those that reverse multidrug resistance. However, the phenothiazines chlorpromazine and trifluoperazine, which also effectively reverse multidrug resistance, were poor inhibitors of the photoaffinity labeling of P-glycoprotein. Chloroquine, propranolol, or atropine, which only partially reversed the drug resistance, also did not inhibit photolabeling. Naphthalene sulfonamide calmodulin inhibitors, W7 and W5, as well as many other drugs that did not circumvent multidrug resistance, did not inhibit photolabeling. These studies suggest that most, but not all, agents that phenotypically suppress multidrug resistance also inhibit drug binding to a site on P-glycoprotein with which a photoaffinity analog of vinblastine interacts

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A Potato cDNA Encoding a Homologue of Mammalian Multidrug Resistant P-Glycoprotein  

Science.gov (United States)

A homologue of the multidrug resistance (MDR) gene was obtained while screening a potato stolon tip cDNA expression library with S-15-labeled calmodulin. The mammalian MDR gene codes for a membrane-bound P-glycoprotein (170-180 kDa) which imparts multidrug resistance to cancerous cells. The potato cDNA (PMDR1) codes for a polypeptide of 1313 amino acid residues (ca. 144 kDa) and its structural features are very similar to the MDR P-glycoprotein. The N-terminal half of the PMDR1-encoded protein shares striking homology with its C-terminal half, and each half contains a conserved ATP-binding site and six putative transmembrane domains. Southern blot analysis indicated that potato has one or two MDR-like genes. PMDR1 mRNA is constitutively expressed in all organs studied with higher expression in the stem and stolon tip. The PMDR1 expression was highest during tuber initiation and decreased during tuber development.

Wang, W.; Takezawa, D.; Poovaiah, B. W.

1996-01-01

9

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english 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 v [...] olunteers (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.

C.G., Machado; R.T., Calado; A.B., Garcia; R.P., Falcão.

1653-16-01

10

Cortisol is transported by the multidrug resistance gene product P-glycoprotein  

OpenAIRE

The physiology of the multidrug transporter P-glycoprotein (Pgp) is still poorly understood. We now show evidence that cell lines with a high expression of Pgp display a reduced accumulation of cortisol and an ATP-dependent outward transport of the hormone. Cortisol efflux from Pgp negative cells does not have such an active component. Further we show that the steroid hormones cortisol, testosterone, and progesterone cause an immediate, dose-dependent increase of daunorubicin accumulation in ...

Kalken, C. K.; Broxterman, H. J.; Pinedo, H. M.; Feller, N.; Dekker, H.; Lankelma, J.; Giaccone, G.

1993-01-01

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Immunohistochemical detection of multidrug resistance associated P-glycoprotein in tumour and stromal cells of human cancers.  

OpenAIRE

The distribution of Gp 170, a multidrug resistance (MDR) associated glycoprotein, also called P-glycoprotein (P-gp), was examined by immunohistochemistry, using C219 and MRK16 monoclonal antibodies. Sixty-five tumour tissues were studied which included 40 non-lymphoid tumours, 15 chemoresistant non-Hodgkin's lymphomas and 10 Hodgkin's disease. The study was performed on both cryostat and special fixation processed and paraplast embedded (ModAMeX) sections. The latter method preserves fixation...

Schlaifer, D.; Laurent, G.; Chittal, S.; Tsuruo, T.; Soues, S.; Muller, C.; Charcosset, J. Y.; Alard, C.; Brousset, P.; Mazerrolles, C.

1990-01-01

12

Molecular basis of preferential resistance to colchicine in multidrug-resistant human cells conferred by Gly-185 ? Val-185 substitution in P-glycoprotein  

International Nuclear Information System (INIS)

Expression of P-glycoprotein, encoded by the human MDR1 gene, results in cross-resistance to many lipophilic cytotoxic drugs (multidrug resistance). P-glycoprotein is believed to function as an energy-dependent efflux pump that is responsible for decreased drug accumulation in multidrug-resistant cells. Previous work showed that preferential resistance to colchicine in a colchicine-selected multidrug-resistant cell line was caused by spontaneous mutations in the MDR1 gene that resulted in a Gly-185 ? Val-185 substitution in P-glycoprotein. The authors have now compared transfectant cell lines expressing the wild-type Gly-185 or the mutant Val-185 P-glycoprotein with regard to their levels of resistance to and accumulation and binding of different drugs. In cells expressing the mutant protein, increased resistance to colchicine and decreased resistance to vinblastine correlated with a decreased accumulation of colchicine and increased accumulation of vinblastine. Expression of the mutant P-glycoprotein also resulted in significantly increased resistance to epipodophyllotoxin and decreased resistance to vincristine and actinomycin D; smaller changes in resistance were observed for several other drugs. Unexpectedly, the mutant P-glycoprotein showed increased binding of photoactive analogs of vinblastine and verapamil and the photoactive compound azidopine and decreased binding of a photoactive colchicine analog. These results suggest that the Gly-185 ? Val-185 substigest that the Gly-185 ? Val-185 substitution affects not the initial drug-binding site of P-glycoprotein but another site, associated with the release of P-glycoprotein-bound drugs to the outside of the cell

13

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

DEFF Research Database (Denmark)

An Ehrlich ascites tumour cell line (EHR2) was selected in vivo for resistance to mitoxantrone (MITOX). The resistant cell line (EHR2/MITOX) was 6123-, 33-, and 30-fold-resistant to mitoxantrone, daunorubicin, and etoposide, respectively, but retained sensitivity to vincristine. The resistant cells showed moderate sensitisation to mitoxantrone on treatment with verapamil or cyclosporin A. Compared with EHR2, the multidrug resistance-associated protein mRNA was increased 13-fold in EHR2/MITOX. Western blot analysis showed an unchanged, weak expression of P-glycoprotein. Topoisomerase IIalpha was reduced to one-third in EHR2/MITOX relative to EHR2 cells, whereas topoisomerase IIbeta was present in EHR2 but could not be detected in EHR2/MITOX. In the resistant subline, net accumulation of MITOX (120 min) and daunorubicin (60 min) was reduced by 43% and 27%, respectively, as compared with EHR2. 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 to be associated with: 1) a quantitative reduction in topoisomerase IIalpha and beta protein; 2) reduced drug accumulation, probably as a result of increased expression of a novel transport protein with ATPase activity; and 3) increased expression of MRP mRNA.

Nielsen, D; Eriksen, J

2000-01-01

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The novel bis-benzylisoquinoline PY35 reverses P-glycoprotein-mediated multidrug resistance.  

Science.gov (United States)

Multidrug resistance (MDR) to chemotherapeutic drugs is the main cause of chemotherapy failure in cancer treatment, and it generally results from expression of ATP-dependent efflux pump P-glycoprotein (P-gp). MDR reversal agents typically act by inhibiting the drug efflux activity of P-gp, thereby increasing intracellular drug levels. PY35 is a novel 5-substituted tetrandrine (Tet) derivative (CN Application No. 201210238709.6). The present study was performed to investigate the ability of PY35 to reverse P-gp-mediated MDR and its mechanism in resistant K562/Adriamycin (ADM), MCF-7/ADM cells and their sensitive cell lines K562 and MCF-7. The ability of PY35 to reverse drug resistance was evaluated by MTT assay. The results showed that PY35 can reverse MDR more effectively than the drug prototype?Tet. The P-gp function was assessed by the Rhodamine 123 (Rho-123; a P-gp substrate) uptake assay with flow cytometry (FCM) and laser scanning confocal microscopes (LSCM); it showed that the MDR cells pumped Rho-123 out the cells, while their sensitive cells scarcely showed efflux. The presence of PY35 efficiently decreased the efflux of the Rho-123, showing that PY35 can reverse P-gp-mediated MDR by increasing the intracellular concentration of Rho-123. The intracellular accumulation of ADM was analyzed by FCM and showed that the coadministration of PY35 and ADM had clearer accumulation than the treatment of Tet and ADM, and was also more evident than treatment with only ADM. The effect of PY35 on the expression of P-gp was assessed by western blotting. The results indicated that PY35 does not inhibit the expression level of the P-gp. This study indicated that PY35 can effectively reverse P-gp-mediated MDR, not by inhibiting the expression of P-gp, but by the coadministration of PY35 and ADM that could increase the intracellular accumulation of drugs. Thus, PY35 may be a potential inhibitor to overcome drug resistance. PMID:25017650

Cao, Zhonglian; Wright, Meredith; Cheng, Jiekai; Huang, Xiaoxing; Liu, Li; Wu, Lixing; Yang, Ping

2014-09-01

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

Directory of Open Access Journals (Sweden)

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.

Li Yan

2009-11-01

16

Drug accumulation in the presence of the multidrug resistance pump : dissociation between verapamil accumulation and the action of P-glycoprotein  

DEFF Research Database (Denmark)

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 resistant P388 leukemia cell line, P388/ADR. The time course of accumulation of these drugs, and the effect of energy starvation and the presence of chloroquine on the level of their steady-state accumulation were quite disparate. Vinblastine inhibited the accumulation of verapamil whereas it enhanced the accumulation of daunomycin, another classic substrate of P-glycoprotein. Verapamil did not compete with the intracellular binding sites of vinblastine. In all these aspects, vinblastine behaved as a typical substrate of P-glycoprotein but verapamil did not. Our data suggest that verapamil is a reverser of P-glycoprotein but that its intracellular accumulation is not affected by this membrane-bound transporter.

Ayesh, S; Litman, Thomas

1997-01-01

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Multidrug resistance proteins: role of P-glycoprotein, MRP1, MRP2, and BCRP (ABCG2) in tissue defense  

International Nuclear Information System (INIS)

In tumor cell lines, multidrug resistance is often associated with an ATP-dependent decrease in cellular drug accumulation which is attributed to the overexpression of certain ATP-binding cassette (ABC) transporter proteins. ABC proteins that confer drug resistance include (but are not limited to) P-glycoprotein (gene symbol ABCB1), the multidrug resistance protein 1 (MRP1, gene symbol ABCC1), MRP2 (gene symbol ABCC2), and the breast cancer resistance protein (BCRP, gene symbol ABCG2). In addition to their role in drug resistance, there is substantial evidence that these efflux pumps have overlapping functions in tissue defense. Collectively, these proteins are capable of transporting a vast and chemically diverse array of toxicants including bulky lipophilic cationic, anionic, and neutrally charged drugs and toxins as well as conjugated organic anions that encompass dietary and environmental carcinogens, pesticides, metals, metalloids, and lipid peroxidation products. P-glycoprotein, MRP1, MRP2, and BCRP/ABCG2 are expressed in tissues important for absorption (e.g., lung and gut) and metabolism and elimination (liver and kidney). In addition, these transporters have an important role in maintaining the barrier function of sanctuary site tissues (e.g., blood-brain barrier, blood-cerebral spinal fluid barrier, blood-testis barrier and the maternal-fetal barrier or placenta). Thus, these ABC transporters are increasingly recognized for their ability to modulate the absozed for their ability to modulate the absorption, distribution, metabolism, excretion, and toxicity of xenobiotics. In this review, the role of these four ABC transporter proteins in protecting tissues from a variety of toxicants is discussed. Species variations in substrate specificity and tissue distribution of these transporters are also addressed since these properties have implications for in vivo models of toxicity used for drug discovery and development

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Tetrandrine and fangchinoline, bisbenzylisoquinoline alkaloids from Stephania tetrandra can reverse multidrug resistance by inhibiting P-glycoprotein activity in multidrug resistant human cancer cells.  

Science.gov (United States)

The overexpression of ABC transporters is a common reason for multidrug resistance (MDR) in cancer cells. In this study, we found that the isoquinoline alkaloids tetrandrine and fangchinoline from Stephania tetrandra showed a significant synergistic cytotoxic effect in MDR Caco-2 and CEM/ADR5000 cancer cells in combination with doxorubicin, a common cancer chemotherapeutic agent. Furthermore, tetrandrine and fangchinoline increased the intracellular accumulation of the fluorescent P-glycoprotein (P-gp) substrate rhodamine 123 (Rho123) and inhibited its efflux in Caco-2 and CEM/ADR5000 cells. In addition, tetrandrine and fangchinoline significantly reduced P-gp expression in a concentration-dependent manner. These results suggest that tetrandrine and fangchinoline can reverse MDR by increasing the intracellular concentration of anticancer drugs, and thus they could serve as a lead for developing new drugs to overcome P-gp mediated drug resistance in clinic cancer therapy. PMID:24856768

Sun, Yan Fang; Wink, Michael

2014-01-01

19

[Expression of P-glycoprotein as a multidrug resistance gene product in human reactive astrocytes and astrocytoma].  

Science.gov (United States)

The immunohistochemical detection of multidrug resistance (MDR1) gene products and their mRNA within brain tumor cells has already been described by Fojo et al. 1987. 63 specimens of astrocytomas and glioblastomas were analysed in the present study (Grading type 1 to 4) by means of the monoclonal antibody JSB1. The endothelial cells were positive only in astrocytic tumors with a grading of 1. Increasing tumor grading resulted in more positive immunological reactions in tumor cells. The most impressive reaction could be found in anaplastic astrocytoma and glioblastoma (G3 and G4). Overexpression of this P-glycoprotein, a plasma membrane component of a relative molecular mass of 170 kDa was not only found in tumor cells of anaplastic astrocytomas, but also in endothelial cells and some non-neoplastic brain diseases. Positive immunological reactions in protoplasmatic astrocytes could be demonstrated in cases of phenylketonuria (1/1), tuberculous leptomeningitis (2/2), SSPE (3/4), X-ray necrosis (1/1) and necrotizing viral encephalitis (1/4). According to this, it seems that astrocytes are able to express P-glycoprotein under the influence of some special metabolic conditions. This underlines the detoxicating function of reactive astrocytes within the total number of cells in the CNS. PMID:7947620

Dietzmann, K; Bossanyi, P V; Franke, D S

1994-07-01

20

Glucosylceramide synthase blockade down-regulates P-glycoprotein and resensitizes multidrug-resistant breast cancer cells to anticancer drugs.  

Science.gov (United States)

Overexpression of glucosylceramide synthase (GCS), a pivotal enzyme in glycolipid biosynthesis, contributes to cancer cell resistance to chemotherapy. We previously showed that transfection of doxorubicin-resistant MCF-7-AdrR cells with GCS antisense restored cell sensitivity to doxorubicin and greatly enhanced sensitivity to vinblastine and paclitaxel. In that study, doxorubicin promoted generation of ceramide in MCF-7-AdrR/GCS antisense cells; the present study implicates factors in addition to ceramide that augment sensitivity to chemotherapy. Although GCS antisense cells showed enhanced ceramide formation compared with MCF-7-AdrR when challenged with paclitaxel, GCS antisense cells also showed a 10-fold increase in levels of intracellular drug (paclitaxel and vinblastine). In addition, transfected cells had dramatically decreased expression (80%) of P-glycoprotein and a 4-fold decrease in the level of cellular gangliosides. Chemical inhibition of GCS produced the same effects as antisense transfection: exposure of MCF-7-AdrR cells to the GCS inhibitor 1-phenyl-2-palmitoylamino-3-morpholino-1-propanol (PPMP, 5.0 micromol/L, 4 days) decreased ganglioside levels, restored sensitivity to vinblastine, enhanced vinblastine uptake 3-fold, and diminished expression of MDR1 by 58%, compared with untreated controls. A similar effect was shown in vinblastin-resistant KB-V0.01 cells; after 7 days with PPMP (10 micromol/L), MDR1 expression fell by 84% and P-glycoprotein protein levels decreased by 50%. MCF-7-AdrR cells treated with small interfering RNAs to specifically block GCS also showed a dramatic decrease in MDR1 expression. This work shows that limiting GCS activity down-regulates the expression of MDR1, a phenomenon that may drive the chemosensitization associated with blocking ceramide metabolism. The data suggest that lipids play a role in the expression of multidrug resistance. PMID:15867385

Gouazé, Valérie; Liu, Yong-Yu; Prickett, Carlton S; Yu, Jing Y; Giuliano, Armando E; Cabot, Myles C

2005-05-01

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Modulation of P-glycoprotein-mediated multidrug resistance in K562 leukemic cells by indole-3-carbinol  

International Nuclear Information System (INIS)

Resistance to chemotherapeutic drugs is one of the major problems in the treatment of cancer. P-glycoprotein (P-gp) encoded by the mdr gene is a highly conserved protein, acts as a multidrug transporter, and has a major role in multiple drug resistance (MDR). Targeting of P-gp by naturally occurring compounds is an effective strategy to overcome MDR. Indole-3-carbinol (I3C), a glucosinolates present in cruciferous vegetables, is a promising chemopreventive agent as it is reported to possess antimutagenic, antitumorigenic, and antiestrogenic properties in experimental studies. In the present investigation, the potential of I3C to modulate P-gp expression was evaluated in vinblastine (VBL)-resistant K562 human leukemic cells. The resistant K562 cells (K562/R10) were found to be cross-resistant to vincristine (VCR), doxorubicin (DXR), and other antineoplastic agents. I3C at a nontoxic dose (10 x 10-3 M) enhanced the cytotoxic effects of VBL time dependently in VBL-resistant human leukemia (K562/R10) cells but had no effect on parent-sensitive cells (K562/S). The Western blot analysis of K 562/R 10 cells showed that I3C downregulates the induced levels of P-gp in resistant cells near to normal levels. The quantitation of immunocytochemically stained K562/R10 cells showed 24%, 48%, and 80% decrease in the levels of P-gp by I3C for 24, 48, and 72 h of incubation. The above features thus indicate that I3C could be used as a novel modulator of P-gp-mediated multidra novel modulator of P-gp-mediated multidrug resistance in vitro and may be effective as a dietary adjuvant in the treatment of MDR cancers

22

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

Science.gov (United States)

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. PMID:25765837

Su, Shan; Cheng, Xinlai; Wink, Michael

2015-02-15

23

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

OpenAIRE

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 assa...

Ayudhya, Nitaya S. N.; Samlee Mankhetkorn

2009-01-01

24

Inhibition of P-glycoprotein (ABCB1)- and multidrug resistance-associated protein 1 (ABCC1)-mediated transport by the orally administered inhibitor, CBT-1®  

OpenAIRE

Cellular expression of ATP-binding cassette (ABC) transport proteins, such as P-glycoprotein (Pgp), multidrug resistance-associated protein (MRP1), or ABCG2, is known to confer a drug-resistant phenotype. Thus, the development of effective transporter inhibitors could be of value to cancer treatment. CBT-1® is a bisbenzylisoquinoline plant alkyloid currently in development as a Pgp inhibitor. We characterized its interactions with the three major ABC transporters associated with drug resista...

Robey, Robert W.; Shukla, Suneet; Finley, Elizabeth M.; Oldham, Robert K.; Barnett, Daryl; Ambudkar, Suresh V.; Fojo, Tito; Bates, Susan E.

2007-01-01

25

Expression of multidrug resistance gene and P-glycoprotein in nasopharyngealcarcinoma cells after irradiation  

International Nuclear Information System (INIS)

Objective: To mimick a clinical fractionated protocol of exposure to X-radiation in vitro in order to investigate the changes in the function of MDR1 and P-gp in nasopharyngeal carcinoma (NPC) CNE cell before and after irradiation to determine the sequential order of radiotherapy and chemotherapy or the time of chemotherapy after radiotherapy in the treatment of NPC. Methods: Exponentially growing CNE cells were treated with fractionated X-radiation with total dose of 10 Gy (2 Gy per day for 5 days consecutively) in vitro. The expression of MDR1 gene was examined in CNE cells before irradiation and on days 4,8,13,17 and 21 after irradiation by RT-PCR, and its protein P-gp were detected by immunocytochemistry. The function of multidrug resistance protein P-gp was examined by MTT method. Results: Expression of MDR1 gene was below the level of detection before irradiation. Irradiation induced an overexpression of MDR1 gene on day 4, expression of MDR1 was decreased from day 8 to day 21. The overall expression of MDR1 was significantly more than that before irradiation (P<0.05) Expression of P-gp was below the level of detection before irradiation, which demonstrated that irradiation induced an overexpression of P-gp. This overexpression was increased from day 8 to day 21. The overpression of MDR1 gene was maintained dining a short period, however, the emergence of overpression of protein P-gp was later than that of MDR1 gene. Resistance index was 1 for both pre-irradiatiistance index was 1 for both pre-irradiation and on day 8, and up to 8,10,11.2 on days 13, 17 and 21, respectively. The change of resistance index was accordant with the condition of overexpression of P-gp . Conclusions: Expression of P-gp in nasopharyngeal carcinoma (NPC) CNE cell was below the level of detection before irradiation. Irradiation can induce an overexpression of MDR1 gene and its protein P-gp in CNE cells. The overexpression of MDR1 gene and its protein P-gp lasted a long term. (authors)

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Identification of the Interaction between P-Glycoprotein and Anxa2 in Multidrug-resistant Human Breast Cancer Cells  

Directory of Open Access Journals (Sweden)

Full Text Available Objective To explore the interaction of Anxa2 with P- Glycoprotein (P-gp in the migration and invasion of the multidrug-resistant (MDR human breast cancer cell line MCF-7/ADR. Methods A pair of short hairpin RNA (shRNA targeting P-gp was transfected into MCF-7/ADR cells, and monoclonal cell strains were screened. The expression of P-gp was detected by Western blot. Transwell chambers were used to observe the cell migration capacity and invasion ability. The interaction between P-gp and Anxa2 was examined by immunoprecipitation and immunofluorescence confocal microscopy analyses. Results P-gp expression was significantly knocked down, and there were notable decreasing trends in the migration and invasion capability of MDR breast cancer cells (P<0.05. There was a close interaction between Anxa2 and P-gp.Conclusions MCF-7/ADR is an MDR human breast cancer cell line with high migration and invasion abilities. The knockdown of P-gp notably impaired the migration and invasion abilities of the tumor cells. The interaction of Anxa2 with P-pg may play an important role in the enhanced invasiveness of MDR human breast cancer cells.

Hai-chang Zhang

2012-06-01

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N-ethylmaleimide increases P-glycoprotein photoaffinity labeling with iodoaryl-azidoprazosin in multidrug resistant cells.  

Science.gov (United States)

P-glycoprotein (P-gp) mediates a multidrug resistance (MDR) phenotype in tumor cell lines selected with lipophilic cytotoxic drugs. Transport studies using purified P-glycoprotein reconstituted into defined liposomes have shown energy-dependent drug efflux of structurally dissimilar drugs. In this report, we have examined the effects of N-ethylmaleimide, a potent inhibitor of the P-gp ATPase, on P-gp drug binding in intact MDR cells and in plasma membranes. Our results show that short term treatment of MDR cells with 1-50 microM N-ethylmaleimide led to a concentration dependent increase in P-gp photoaffinity labeling with iodoaryl-azidoparazosin (IAAP). In addition, N-ethylmaleimide increases [3H] vinblastine accumu-lation in drug-resistant but not in sensitive cells. Comparison of IAAP photolabeled P-gp from intact cells with or without N-ethylmaleimide treatment did not show differences in the pattern of IAAP photolabeled peptides. Thus, the observed increase in P-gp photolabeling with IAAP in N-ethylmaleimide treated cells is not due to photolabeling at different sites. Incubation of MDR cells with [14C] N-ethylmaleimide showed that P-gp is directly modified at several Cysteine residues, as found from a complete proteolytic digestion of [14C] Nethylmaleimide labeled P-gp. The comparison of V8 staphylococcus aureas peptides from [14C] Nethylmaleimide or IAAP modified P-gp showed some peptides to co-migrate on SDS PAGE. However, modification of plasma membranes from drug resistant cells treated with N-ethylmaleimide did not show a dose-dependent increase in P-gp photolabeling with IAAP as seen with intact MDR cells. Interestingly, N-ethylmaleimide increases P-gp phosphorylation by inhibiting the turnover of Pgp phosphates. However, inhibition of P-gp phosphorylation with calyculin A did not show an increase in P-gp photolabeling in MDR cells. Taken together, the results of this study suggest that N-ethylmaleimide potentiates P-gp photolabeling with IAAP by inhibiting P-gp ATPase thereby increasing the local concentration of IAAP in intact MDR cells. Furthermore, inhibition of P-gp ATPase by N-ethylmaleimide does not lead to conformational changes that affects P-gp drug binding. PMID:9066677

Wang, Y; Georges, E

1997-01-01

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Comparison of western blot analysis and immunocytochemical detection of P-glycoprotein in multidrug resistant cells.  

OpenAIRE

A sensitive immunocytochemical technique was developed to detect a 170,000 dalton cell membrane glycoprotein (P-gp) in cell lines resistant to vincristine and vinblastine with varying degrees of resistance. P-gp was shown very clearly using the C219 monoclonal antibody and immunocytochemical detection with either antialkaline phosphate or peroxidase-antiperoxidase with silver gold intensification. There was good correlation between the results obtained with immunocytochemical detection of P-g...

Friedlander, M. L.; Bell, D. R.; Leary, J.; Davey, R. A.

1989-01-01

29

Glicoproteína-P, resistência a múltiplas drogas (MDR) e relação estrutura-atividade de moduladores / P-glycoprotein and multidrug resistance: structure-activity relationships of modulators  

Scientific Electronic Library Online (English)

Full Text Available [...] Abstract in english Multidrug resistance, MDR is a major obstacle for cancer chemotherapy. MDR can be reversed by drugs that vary in their chemical structure and main biological activity. Many efforts have been done to overcome MDR based on studies of structure-activity relationships and in this review we summarize som [...] e aspects of MDR mediated by P-glycoprotein (P-gp), as the most experimentally and clinically tested form of drug resistance. The most significant MDR mechanisms revealed until now are shortly discussed. Physicochemical and structural properties of MDR modulators, measures of the MDR reversal, and QSAR studies are included.

Paula C., Huber; Cintia H., Maruiama; Wanda P., Almeida.

2148-21-01

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Multi-drug resistance in a canine lymphoid cell line due to increased P-glycoprotein expression, a potential model for drug-resistant canine lymphoma.  

Science.gov (United States)

Canine lymphoma is routinely treated with a doxorubicin-based multidrug chemotherapy protocol, and although treatment is initially successful, tumor recurrence is common and associated with therapy resistance. Active efflux of chemotherapeutic agents by transporter proteins of the ATP-Binding Cassette superfamily forms an effective cellular defense mechanism and a high expression of these transporters is frequently observed in chemotherapy-resistant tumors in both humans and dogs. In this study we describe the ABC-transporter expression in a canine lymphoid cell line and a sub-cell line with acquired drug resistance following prolonged exposure to doxorubicin. This sub-cell line was more resistant to doxorubicin and vincristine, but not to prednisolone, and had a highly increased P-glycoprotein (P-gp/abcb1) expression and transport capacity for the P-gp model-substrate rhodamine123. Both resistance to doxorubicin and vincristine, and rhodamine123 transport capacity were fully reversed by the P-gp inhibitor PSC833. No changes were observed in the expression and function of the ABC-transporters MRP-1 and BCRP. It is concluded that GL-40 cells represent a useful model for studying P-gp dependent drug resistance in canine lymphoid neoplasia, and that this model can be used for screening substances as potential P-gp substrates and their capacity to modulate P-gp mediated drug resistance. PMID:24975508

Zandvliet, M; Teske, E; Schrickx, J A

2014-12-01

31

Effect of P-glycoprotein and multidrug resistance associated protein gene expression on Tc-99m MIBI imaging in hepatocellular carcinoma  

International Nuclear Information System (INIS)

P-glycoprotein (Pgp) and multidrug resistance-associated protein (MRP) expressions as well as Tc-99m methoxisobutylisonitrile (MIBI) images were assessed in 25 patients hepatocellular carcinoma (HCC). Tc-99m MIBI imaging was performed 10 minutes after intravenous injection of 20 mCi Tc-99m MIBI. Using immunohistochemical staining, 60% of the HCC lesions showed positive for Pgp and 64% showed positive for MRP. In 3 patients with MIBI uptake, immunohistochemical study of tumor tissue showed no Pgp stained cells. Nevertheless, they were all positive for MRP. The result of Tc-99m MIBI imaging is more related to the expression of Pgp than MRP gene. It is possible that other membrane transporters as well as Pgp and MRP are involved in the efflux of Tc-99m MIBI

32

Selecting surfactants for the maximum inhibition of the activity of the multidrug resistance efflux pump transporter, P-glycoprotein: conceptual development.  

Directory of Open Access Journals (Sweden)

Full Text Available Amphiphilic excipients, such as surfactants, have been shown to be inhibitors of the multidrug resistance (MDR efflux pump transporter protein, P-glycoprotein (Pgp. In vitro studies using manysurfactants have demonstrated that those with an optimum hydrophilic-lipophilic balance (HLB exhibit greater efflux pump inhibition than those that are either very hydrophobic, or very hydrophilic, although the correlation of HLB to Pgp inhibition activity remains weak. Using the data from multiple in vitro studies, a model has been conceptualized that underscores the attributes of both the HLB and the critical micellar concentration (CMC, occurring in tandem, and unable of being varied independently, as key determinants toward prediction of surfactant Pgp inhibition activity. The algorithm that formalizes this concept provides a ‘semi-rational’ method of choosingsurfactants for a specific type of cancer for maximum inhibition of MDR.

Apte Shireesh Prakash

2010-12-01

33

Drug Resistance in Cortical and Hippocampal Slices from Resected Tissue of Epilepsy Patients: No Significant Impact of P-Glycoprotein and Multidrug Resistance-Associated Proteins  

Science.gov (United States)

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 (CBZ), sodium valproate, phenytoin] and two unspecific inhibitors of Pgp and MRPs [verapamil (VPM) and probenecid (PBN)] on seizure-like events (SLEs) 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 SLEs predominantly persisted in the presence of anticonvulsant drugs (90%) and also in the presence of VPM and PBN (86%). Following subsequent co-administration of anti-epileptic drugs and drug transport inhibitors, SLEs 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 CBZ in PBN 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 do not 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. PMID:25741317

Sandow, Nora; Kim, Simon; Raue, Claudia; Päsler, Dennis; Klaft, Zin-Juan; Antonio, Leandro Leite; Hollnagel, Jan Oliver; Kovacs, Richard; Kann, Oliver; Horn, Peter; Vajkoczy, Peter; Holtkamp, Martin; Meencke, Heinz-Joachim; Cavalheiro, Esper A.; Pragst, Fritz; Gabriel, Siegrun; Lehmann, Thomas-Nicolas; Heinemann, Uwe

2015-01-01

34

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

Science.gov (United States)

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 (CBZ), sodium valproate, phenytoin] and two unspecific inhibitors of Pgp and MRPs [verapamil (VPM) and probenecid (PBN)] on seizure-like events (SLEs) 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 SLEs predominantly persisted in the presence of anticonvulsant drugs (90%) and also in the presence of VPM and PBN (86%). Following subsequent co-administration of anti-epileptic drugs and drug transport inhibitors, SLEs 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 CBZ in PBN 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 do not 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. PMID:25741317

Sandow, Nora; Kim, Simon; Raue, Claudia; Päsler, Dennis; Klaft, Zin-Juan; Antonio, Leandro Leite; Hollnagel, Jan Oliver; Kovacs, Richard; Kann, Oliver; Horn, Peter; Vajkoczy, Peter; Holtkamp, Martin; Meencke, Heinz-Joachim; Cavalheiro, Esper A; Pragst, Fritz; Gabriel, Siegrun; Lehmann, Thomas-Nicolas; Heinemann, Uwe

2015-01-01

35

Modulation of multidrug resistance P-glycoprotein activity by antiemetic compounds in human doxorubicin-resistant sarcoma cells (MES-SA/Dx-5): implications on cancer therapy.  

Science.gov (United States)

Multidrug resistance (MDR) in cancer cells is often caused by the high expression of the plasma membrane drug transporter P-glycoprotein (Pgp) associated with an elevated intracellular glutathione (GSH) content in various human tumors. Several chemosensitizers reverse MDR but have significant toxicities. Antiemetic medications are often used for controlling chemotherapy-induced nausea and vomiting in cancer patient. In this in vitro study we investigated if the effects of two common antiemetic drugs such as dimenhydrinate (dime) and ondansentron (onda) and a natural compound (6)-gingerol (ginger), the active principle of ginger root, interfere on Pgp activity and intracellular GSH content in order to evaluate their potential use as chemosensitizing agents in anticancer chemotherapy. The human doxorubicin (doxo) resistant uterine sarcoma cells (MES-SA/Dx5) that overexpress Pgp, were treated with each antiemetic alone (1, 10 and 20 microM) or in combination with different doxo concentrations (2, 4, and 8 microM). We measured the intracellular accumulation and cytotoxicity of doxo (MTT assay), the cellular GSH content (GSH assay) and ROS production (DFC-DA assay), in comparison with verapamil (Ver), a specific inhibitor for Pgp, used as reference molecule. We found that exposure at 2, 4 and 8 microM doxo concentrations in the presence of dime, onda and ginger enhanced significantly doxo accumulation and cytotoxicity on resistant MES-SA/Dx5 cells when compared with doxo alone. Moreover, treatment with ginger (20 microM) increased cellular GSH content (greater than 10 percent) in resistant cells, while ROS production remained below the control values for all antiemetic compounds at all concentrations. These findings provide the rationale for innovative clinical trials of antiemetics or their derivatives as a new potential generation of chemosensitizers to improve effectiveness of the anticancer drugs in MDR human tumours. PMID:24382184

Angelini, A; Conti, P; Ciofani, G; Cuccurullo, F; Di Ilio, C

2013-01-01

36

Consequences of cell-to-cell P-glycoprotein transfer on acquired multidrug resistance in breast cancer: a cell population dynamics model  

Science.gov (United States)

Background Cancer is a proliferation disease affecting a genetically unstable cell population, in which molecular alterations can be somatically inherited by genetic, epigenetic or extragenetic transmission processes, leading to a cooperation of neoplastic cells within tumoural tissue. The efflux protein P-glycoprotein (P-gp) is overexpressed in many cancer cells and has known capacity to confer multidrug resistance to cytotoxic therapies. Recently, cell-to-cell P-gp transfers have been shown. Herein, we combine experimental evidence and a mathematical model to examine the consequences of an intercellular P-gp trafficking in the extragenetic transfer of multidrug resistance from resistant to sensitive cell subpopulations. Methodology and Principal Findings We report cell-to-cell transfers of functional P-gp in co-cultures of a P-gp overexpressing human breast cancer MCF-7 cell variant, selected for its resistance towards doxorubicin, with the parental sensitive cell line. We found that P-gp as well as efflux activity distribution are progressively reorganized over time in co-cultures analyzed by flow cytometry. A mathematical model based on a Boltzmann type integro-partial differential equation structured by a continuum variable corresponding to P-gp activity describes the cell populations in co-culture. The mathematical model elucidates the population elements in the experimental data, specifically, the initial proportions, the proliferative growth rates, and the transfer rates of P-gp in the sensitive and resistant subpopulations. Conclusions We confirmed cell-to-cell transfer of functional P-gp. The transfer process depends on the gradient of P-gp expression in the donor-recipient cell interactions, as they evolve over time. Extragenetically acquired drug resistance is an additional aptitude of neoplastic cells which has implications in the diagnostic value of P-gp expression and in the design of chemotherapy regimens. Reviewers This article was reviewed by Leonid Hanin, Anna Marciniak-Czochra and Marek Kimmel. PMID:21269489

2011-01-01

37

Grape Seed Procyanidin Reversal of P-glycoprotein Associated Multi-Drug Resistance via Down-regulation of NF-?B and MAPK/ERK Mediated YB-1 Activity in A2780/T Cells  

OpenAIRE

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 c...

Zhao, Bo-xin; Sun, Ya-bin; Wang, Sheng-qi; Duan, Lian; Huo, Qi-lu; Ren, Fei; Li, Guo-feng

2013-01-01

38

Methoxylation of 3',4'-aromatic side chains improves P-glycoprotein inhibitory and multidrug resistance reversal activities of 7,8-pyranocoumarin against cancer cells.  

Science.gov (United States)

The overexpression of P-glycoprotein (Pgp), an ATP-driven membrane exporter of hydrophobic xenobiotics, is one of the major causes of multidrug resistance (MDR) in cancer cells. Through extensive screening we have found that the extracts of Peucedanum praeruptorum Dunn. and one of the major components (+/-)-praeruptorin A (PA) may reverse Pgp-mediated multidrug resistance. Studies on novel PA derivatives have shown that (+/-)-3'-O,4'-O-dicinnamoyl-cis-khellactone (DCK) is more active than PA or verapamil and is a non-competitive inhibitor of Pgp. Here, we report that methoxylation of the cinnamoyl groups on DCK may further enhance its bioactivity. The structure-activity relationship is demonstrated by comparing two new pyranocoumarins (+/-)-3'-O,4'-O-bis(3,4-dimethoxycinnamoyl)-cis-khellactone (DMDCK) and (+/-)-3'-O,4'-O-bis(4-methoxycinnamoyl)-cis-khellactone (MMDCK). While the co-existence of 3- and 4-methoxy groups on cinnamoyl remarkably enhanced the Pgp-inhibitory activity, the lone existence of the 4-methoxy group on cinnamoyl reduced the activity. Contrary to DCK, DMDCK promoted the binding of UIC2 antibody to Pgp which signifies a conformational change of Pgp similar to that induced by transport substrates. While DCK moderately stimulated the basal Pgp-ATPase activity, DMDCK inhibited the activity. A pharmacophore search with verapamil-based template revealed that four functional groups of DMDCK could be simultaneously involved in interaction with Pgp whereas for DCK or MMDCK only three groups were involved. It is speculated that the additional 3-methoxy group on cinnamoyl allows DMDCK to interact more efficiently with Pgp substrate site(s). If DMDCK was tightly bind to Pgp substrate site(s) the complexes could be inactive with regard to transportation and ATP hydrolysis could also be inhibited. PMID:18313307

Fong, Wang-Fun; Shen, Xiao-Ling; Globisch, Christoph; Wiese, Michael; Chen, Guang-Ying; Zhu, Guo-Yuan; Yu, Zhi-Ling; Tse, Anfernee Kai-Wing; Hu, Ying-Jie

2008-04-01

39

Reversal of P-glycoprotein-mediated multidrug resistance by CD44 antibody-targeted nanocomplexes for short hairpin RNA-encoding plasmid DNA delivery.  

Science.gov (United States)

Multidrug resistance (MDR) remains one of the major reasons for the reductions in efficacy of many chemotherapeutic agents in cancer therapy. As a classical MDR phenotype of human malignancies, the adenosine triphosphate binding cassette (ABC)-transporter P-glycoprotein (MDR1/P-gp) is an efflux protein with aberrant activity that has been linked to multidrug resistance in cancer. For the reversal of MDR by RNA interference (RNAi) technology, an U6-RNA gene promoter-driven expression vector encoding anti-MDR1/P-gp short hairpin RNA (shRNA) molecules was constructed (abbreviated pDNA-iMDR1-shRNA). This study explored the feasibility of using Pluronic P123-conjugated polypropylenimine (PPI) dendrimer (P123-PPI) as a carrier for pDNA-iMDR1-shRNA to overcome tumor drug resistance in breast cancer cells. P123-PPI functionalized with anti-CD44 monoclonal antibody (CD44 receptor targeting ligand) (anti-CD44-P123-PPI) can efficiently condense pDNA into nanocomplexes to achieve efficient delivery of pDNA, tumor specificity and long circulation. The in vitro studies methodically evaluated the effect of P123-PPI and anti-CD44-P123-PPI on pDNA-iMDR1-shRNA delivery and P-gp downregulation. Our in vitro results indicated that the P123-PPI/pDNA and anti-CD44-P123-PPI/pDNA nanocomplexes with low cytotoxicity revealed higher transfection efficiency compared with the PPI/pDNA nanocomplexes and Lipofectamine™ 2000 in the presence of serum. The nanocomplexes loaded with pDNA-iMDR1-shRNA against P-gp could reverse MDR accompanied by the suppression of MDR1/P-gp expression at the mRNA and protein levels and improve the internalization and cytotoxicity of Adriamycin (ADR) in the MCF-7/ADR multidrug-resistant cell line. BALB/c nude mice bearing MCF-7/ADR tumor were utilized as a xenograft model to assess antitumor efficacy in vivo. The results demonstrated that the administration of anti-CD44-P123-PPI/pDNA-iMDR1-shRNA nanocomplexes combined with ADR could inhibit tumor growth more efficiently than ADR alone. The enhanced therapeutic efficacy of ADR may be correlated with increased accumulation of ADR in drug-resistant tumor cells. Consequently, these results suggested that the use of pDNA-iMDR1-shRNA-loaded nanocomplexes may be a promising gene delivery strategy to reverse MDR and improve the effectiveness of chemotherapy. PMID:25662500

Gu, Jijin; Fang, Xiaoling; Hao, Junguo; Sha, Xianyi

2015-03-01

40

Comparative uptake of Tc-99m sestamibi and Tc-99m tetrofosmin in cancer cells and tissue expressing P-Glycoprotein or multidrug resistance associated protein  

International Nuclear Information System (INIS)

99mTc-sestamibi(MIBI) and 99mTc-tetrofosmin have been used as substrates for P-glycoprotein (Pgp) and multidrug resistance associated protein (MRP), which are closely associated with multidrug resistance of the tumors. To understand different handling of radiotracers in cancer cell lines expressing Pgp and MRP, we compared cellular uptakes of 99mTc-MIBI and 99mTc-tetrofosmin. The effects of cyclosporin A (CsA), well-known multidrug resistant reversing agent, on the uptake of both tracers were also compared. HCT15/CL02 human colorectal cancer cells for Pgp expressing cells, and human non-small cell lung cancer A549 cells for MRP expressing cells, were used for in vitro and in vivo studies. RT-PCR, western blot analysis and immunohistochemistry were used for detection of Pgp and MRP. MDR-reversal effect with CsA was evaluated at different drug concentrations after incubation with MIBI or tetrofosmin. Radioactivities of supernatant and pellet were measured with gamma well counter. Tumoral uptake of the tracers were measured from tumor bearing nude mice treated with or without CsA. RT-PCR, western blot analysis of the cells and immunochemical staining revealed selective expression of Pgp and MRP for HCT15/CL02 and A549 cells, respectively. There were no significant difference in cellular uptakes of both tracers in HCT15/CL02 cells, but MIBI uptake was slightly higher than that of tetrofosmin in A549 cells. Co-incubation with CsAsmin in A549 cells. Co-incubation with CsA resulted in a increase in cellular uptakes of MIBI and tetrofosmin. Uptake of MIBI or tetrofosmin in HCT15/CL02 cells was increased by 10-and 2.4-fold, and by 7.5 and 6.3-fold in A549 cells, respectively. Percentage increase of MIBI was higher than that of tetrofosmin with CsA for both cells (? < 0.05). In vivo biodistribution study showed that MIBI (114% at 10 min, 257% at 60 min, 396% at 24C min) and tetrofosmin uptake (110% at 10 min, 205% at 60 min, 410% at 240 min) were progressively increased by the time, up to 240 min with CsA. But increases in tumoral uptake were not significantly different between MIBI and tetrofosmin for both tumors. MIBI seems to be a better tracer than tetrofosmin for evaluating MDR reversal effect of the modulators in vitro, but these differences were not evident in vivo tumoral uptake. Both MIBI and tetrofosmin seem to be suitable tracers for imaging Pgp-and MRP=mediated drug resistance in tumors

41

A novel compound RY10-4 downregulates P-glycoprotein expression and reverses multidrug-resistant phenotype in human breast cancer MCF-7/ADR cells.  

Science.gov (United States)

P-glycoprotein (P-gp), an important efflux transporter, is encoded by the MDR1 class of genes and is a major element of the multidrug resistance (MDR) phenomenon in breast cancers. The most common approved cause of MDR in cancer tissues is the over-expression of P-gp. At present, a novel potent anti-tumor compound RY10-4 has been synthesized by our team, which has a similar structure close to protoapigenone. We chose MCF-7/ADR cells, an adriamycin (ADR) - selected human breast tumor cell line with the MDR phenotype, to study the anticancer features of this novel compound in our experiments. In cytotoxicity and apoptosis tests, it was shown that RY10-4 significantly inhibited cell growth, induced apoptosis, potentiated ADR cytotoxicity and restored chemotherapy sensitivity in the MDR cancer cells. Furthermore, our results suggested that RY10-4 reversed MDR partially by down-regulation of P-gp and MDR1 expressions in the MCF-7/ADR cell line. Besides, it is seen that RY10-4 could reduce the intracellular ATP level. Our studies give the theoretical basis for the possible clinical applications of RY10-4 alone or in combination with other chemotherapeutic drugs in the treatment of MDR tumors. PMID:25455158

Xue, Pingping; Yang, Xiaofan; Liu, Yang; Xiong, Chaomei; Ruan, Jinlan

2014-10-01

42

Inhibition of P-glycoprotein (ABCB1)- and multidrug resistance-associated protein 1 (ABCC1)-mediated transport by the orally administered inhibitor, CBT-1((R)).  

Science.gov (United States)

Cellular expression of ATP-binding cassette (ABC) transport proteins, such as P-glycoprotein (Pgp), multidrug resistance-associated protein (MRP1), or ABCG2, is known to confer a drug-resistant phenotype. Thus, the development of effective transporter inhibitors could be of value to cancer treatment. CBT-1 is a bisbenzylisoquinoline plant alkyloid currently in development as a Pgp inhibitor. We characterized its interactions with the three major ABC transporters associated with drug resistance - Pgp, MRP1 and ABCG2 - and compared it to other known inhibitors. CBT-1 completely inhibited rhodamine 123 transport from Pgp-overexpressing cells at a concentration of 1muM. Additionally, 1 microM completely reversed Pgp-mediated resistance to vinblastine, paclitaxel and depsipeptide in SW620 Ad20 cells. CBT-1 was found to compete [(125)I]-IAAP labeling of Pgp with an IC(50) of 0.14 microM, and low concentrations of CBT-1 (<1 microM) stimulated Pgp-mediated ATP hydrolysis. In MRP1-overexpressing cells, 10 microM CBT-1 was found to completely inhibit MRP1-mediated calcein transport. CBT-1 at 25 microM did not have a significant effect on ABCG2-mediated pheophorbide a transport. Serum levels of CBT-1 in samples obtained from eight patients receiving CBT-1 increased intracellular rhodamine 123 levels in CD56+ cells 2.1- to 5.7-fold in an ex vivo assay. CBT-1 is able to inhibit the ABC transporters Pgp and MRP1, making it an attractive candidate for clinical trials in cancers where Pgp and/or MRP1 might be overexpressed. Further clinical studies with CBT-1 are warranted. PMID:18234154

Robey, Robert W; Shukla, Suneet; Finley, Elizabeth M; Oldham, Robert K; Barnett, Daryl; Ambudkar, Suresh V; Fojo, Tito; Bates, Susan E

2008-03-15

43

Inhibition of P-glycoprotein (ABCB1)- and multidrug resistance-associated protein 1 (ABCC1)-mediated transport by the orally administered inhibitor, CBT-1®  

Science.gov (United States)

Cellular expression of ATP-binding cassette (ABC) transport proteins, such as P-glycoprotein (Pgp), multidrug resistance-associated protein (MRP1), or ABCG2, is known to confer a drug-resistant phenotype. Thus, the development of effective transporter inhibitors could be of value to cancer treatment. CBT-1® is a bisbenzylisoquinoline plant alkyloid currently in development as a Pgp inhibitor. We characterized its interactions with the three major ABC transporters associated with drug resistance--Pgp, MRP1 and ABCG2—and compared it to other known inhibitors. CBT-1® completely inhibited rhodamine 123 transport from Pgp-overexpressing cells at a concentration of 1 ?M. Additionally, 1 ?M completely reversed Pgp-mediated resistance to vinblastine, paclitaxel and depsipeptide in SW620 Ad20 cells. CBT-1® was found to compete [125I]-IAAP labeling of Pgp with an IC50 of 0.14 ?M, and low concentrations of CBT-1® (< 1 ?M) stimulated Pgp-mediated ATP hydrolysis. In MRP1-overexpressing cells, 10 ?M CBT-1® was found completely inhibit MRP1-mediated calcein transport. CBT-1® at 25 ?M did not have a significant effect on ABCG2-mediated pheophorbide a transport. Serum levels of CBT-1® in samples obtained from eight patients receiving CBT-1® increased intracellular rhodamine 123 levels in CD56+ cells 2.1- to 5.7-fold in an ex vivo assay. CBT-1® is able to inhibit the ABC transporters Pgp and MRP1, making it an attractive candidate for clinical trials in cancers where Pgp and/or MRP1 might be overexpressed. Further clinical studies with CBT-1® are warranted. PMID:18234154

Robey, Robert W.; Shukla, Suneet; Finley, Elizabeth M.; Oldham, Robert K.; Barnett, Daryl; Ambudkar, Suresh V.; Fojo, Tito; Bates, Susan E.

2008-01-01

44

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

Directory of Open Access Journals (Sweden)

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.

Linardi Renata Lehn

2006-01-01

45

Expression and functional activity of the ABC-transporter proteins P-glycoprotein and multidrug-resistance protein 1 in human brain tumor cells and astrocytes.  

Science.gov (United States)

The poor prognosis of glioma patients is partly based on the minor success obtained from chemotherapeutic treatments. Resistance mechanisms at the tumor cell level may be, in addition to the blood-brain barrier, involved in the intrinsic chemo-insensitivity of brain tumors. We investigated the expression of the drug-transporter proteins P-glycoprotein (P-gp) and multidrug-resistance protein 1 (MRP1) in cell lines (N = 24) and primary cell cultures (N = 36) from neuroectodermal tumors, as well as in brain tumor extracts (N = 18) and normal human astrocytes (N = 1). We found that a considerable expression of P-gp was relatively rare in glioma cells, in contrast to MRP1, which was constitutively overexpressed in cells derived from astrocytomas as well as glioblastomas. Also, normal astrocytes cultured in vitro expressed high amounts of MRPI but no detectable P-gp. Meningioma cells frequently co-expressed P-gp and MRP1, while, most of the neuroblastoma cell lines express higher P-gp but lower MRP1 levels as compared to the other tumor types. Both, a drug-exporting and a chemoprotective function of P-gp as well as MRP1 could be demonstrated in selected tumor cells by a significant upregulation of cellular 3H-daunomycin accumulation and daunomycin cytotoxicity via administration of transporter antagonists. Summing up, our data suggest that P-gp contributes to cellular resistance merely in a small subgroup of gliomas, but frequently in neuroblastomas and meningiomas. In contrast, MRP1 is demonstrated to play a constitutive role in the intrinsic chemoresistance of gliomas and their normal cell counterpart. PMID:12125964

Spiegl-Kreinecker, Sabine; Buchroithner, Johanna; Elbling, Leonilla; Steiner, Elisabeth; Wurm, Gabriele; Bodenteich, Angelika; Fischer, Johannes; Micksche, Michael; Berger, Walter

2002-03-01

46

The antiepileptic drug mephobarbital is not transported by P-glycoprotein or multidrug resistance protein 1 at the blood-brain barrier: a positron emission tomography study  

Science.gov (United States)

Summary Aim of this study was to determine whether the carbon-11-labelled antiepileptic drug [11C]mephobarbital is a substrate of P-glycoprotein (Pgp) and can be used to assess Pgp function at the blood-brain barrier (BBB) with positron emission tomography (PET). We performed paired PET scans in rats, wild-type (FVB) and Mdr1a/b(?/?) mice, before and after intravenous administration of the Pgp inhibitor tariquidar (15 mg/kg). Brain-to-blood AUC0-60 ratios in rats and brain AUC0-60 values of [11C]mephobarbital in wild-type and Mdr1a/b(?/?) mice were similar in scan 1 and scan 2, respectively, suggesting that in vivo brain distribution of [11C]mephobarbital is not influenced by Pgp efflux. Absence of Pgp transport was confirmed in vitro by performing concentration equilibrium transport assay in cell lines transfected with MDR1 or Mdr1a. PET experiments in wild-type mice, with and without pretreatment with the multidrug resistance protein (MRP) inhibitor MK571 (20 mg/kg), and in Mrp1(?/?) mice suggested that [11C]mephobarbital is also not transported by MRPs at the murine BBB, which was also supported by in vitro transport experiments using human MRP1-transfected cells. Our results are surprising as phenobarbital, the N-desmethyl derivative of mephobarbital, has been shown to be a substrate of Pgp, which suggests that N-methylation abolishes Pgp affinity of barbiturates. PMID:22342565

Mairinger, Severin; Bankstahl, Jens P.; Kuntner, Claudia; Römermann, Kerstin; Bankstahl, Marion; Wanek, Thomas; Stanek, Johann; Löscher, Wolfgang; Müller, Markus; Erker, Thomas; Langer, Oliver

2013-01-01

47

Reversal of P-glycoprotein-medicated multidrug resistance by LBM-A5 in vitro and a study of its pharmacokinetics in vivo.  

Science.gov (United States)

The overexpression of P-glycoprotein (P-gp) in tumors leads to multidrug resistance (MDR), which is a significant obstacle in clinical cancer chemotherapy. The co-administration of anticancer drugs and MDR modulators is a promising strategy for overcoming this problem. Our study aimed to explore the reversal mechanism and safety of the MDR modulator LBM-A5 in vitro, and evaluate its pharmacokinetics and effects on doxorubicin metabolism in vivo. We evaluated an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay of anticancer agents mediated by LBM-A5, the effect of LBM-A5 on rhodamine123 intracellular accumulation, and the efflux in K562/DOX cells to investigate the reversal mechanisms of LBM-A5. The results showed that LBM-A5 inhibits rhodamine123 efflux and increases intracellular accumulation by inhibiting the efflux pump function of P-gp. Furthermore, the therapeutic index and CYP3A4 activity analysis in vitro suggested that LBM-A5 is reasonably safe to use. Also, LBM-A5 (10 mg/kg body mass) achieved the required plasma concentration in sufficient time to reverse MDR in vivo. Importantly, the LBM-A5 treatment group shared similar doxorubicin (DOX) pharmacokinetics with the free DOX group. Our results suggest that LBM-A5 effectively reverses MDR (EC50 = 483.6 ± 81.7 nmol·L(-1)) by inhibiting the function of P-gp, with relatively ideal pharmacokinetics and in a safe manner, and so may be a promising candidate for cancer chemotherapy research. PMID:25427107

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

2015-01-01

48

The study of relationship between breast cancer 99Tcm-MIBI imaging with the expression of P-glycoprotein and multidrug resistance-associated protein  

International Nuclear Information System (INIS)

Objective: To evaluate the relationship between the uptake, washout of 99Tcm-methoxy-isobutylisonitrile (MIBI) and P-glycoprotein (P-gp) or multidrug resistance-related protein (MRP) expression in 36 breast cancer patients. Methods: 36 patients with untreated breast cancer were studied prospectively a week before surgical operation, all were injected intravenously with 740 MBq 99Tcm-MIBI in the arm contralateral to the lesion. Anterior planar images were acquired at 10 and 180 min after injection and the tumor-to-normal breast ratios (T/N) and washout rates (WR) were calculated. Immunohistochemical analyses of P-gp and MRP expression were used to evaluate the removed tumor tissues after operation and categorized into four groups. The differences of the early T/N ratios, the late T/N ratios and the WR among them were compared. Results: The early T/N ratios in group A and B were higher than that in group D. There was statistic difference between group A and D (P=0.001 ), and also in group B and D (P=0.045). The late T/N ratios had no statistic differences among them (F=0.499, P=0.686). The WR of group A, B, C were higher than that in group D and there were significant differences between them (P99Tcm-MIBI from the lesions and expression of P-gp or MRP in untreated breast cancer patients. 9999Tcm-MIBI imaging with washout analysis might be a useful method for evaluating P-gp or MRP overexpression and their function in breast cancer. (authors)

49

Hypoxia-induced drug resistance: comparison to P-glycoprotein-associated drug resistance.  

Science.gov (United States)

In this report, we investigate several examples of hypoxia-induced drug resistance and compare them with P-glycoprotein associated multidrug resistance (MDR). EMT6/Ro cells exposed to drugs in air immediately after hypoxic treatment developed resistance to adriamycin, 5-fluorouracil, and actinomycin D. However, these cells did not develop resistance to colchicine, vincristine or cisplatin. When the cells were returned to a normal oxygen environment, they lost resistance. There was no correlation between the content of adriamycin and the development of adriamycin resistance induced by hypoxia. There was no difference between the efflux of adriamycin from aerobic cells and that from hypoxia-treated cells. The mRNA for P-glycoprotein was not detected in the hypoxia-treated cells. These results suggest that hypoxia-induced drug resistance is different from P-glycoprotein associated multidrug resistance. PMID:1681885

Sakata, K; Kwok, T T; Murphy, B J; Laderoute, K R; Gordon, G R; Sutherland, R M

1991-11-01

50

Assessment of the in vitro and in vivo properties of a {sup 99m}Tc-labeled inhibitor of the multidrug resistant gene product P-glycoprotein  

Energy Technology Data Exchange (ETDEWEB)

Overexpression of P-glycoprotein (Pgp), which is present in the plasma membrane of various tumor cells and in several normal cell types, contributes to the multidrug resistance (MDR) phenotype of many human cancers. As a prerequisite for therapy, the expression of Pgp must be studied. The available clinical radiopharmaceuticals for studying the expression of Pgp include the lipophilic {sup 99m}Tc cations (sestamibi, tetrofosmin) as well as [{sup 99m}Tc]Q57, [{sup 99m}Tc]Q58, and [{sup 99m}Tc]Q63. Here we describe the in vitro and in vivo properties of the structurally different complex (3-thiapentane-1,5-dithiolato)[[N-(3-phenylpropyl)-N-2(3-quinazoline-2,4 -dionyl)-ethyl]amino-ethylthiolato] oxotechnetium(V) ({sup 99/99m}Tc1) as a potential inhibitor of Pgp. {sup 99}Tc1 enhances the net cell accumulation of Pgp substrates [{sup 3}H]vinblastine, [{sup 3}H]vincristine, [{sup 3}H]colchicine, [{sup 99m}Tc]sestamibi, and [{sup 99m}Tc]tetrofosmin in rat brain endothelial cells (RBE4), an immortalized endothelial cell line that expresses Pgp. In addition, the cell accumulation of {sup 99m}Tc1 could be increased by verapamil and reserpine, which are known Pgp inhibitors. A multitracer approach was used to study the side effects of {sup 99}Tc1 on cell metabolism. The cells were simultaneously incubated with [{sup 99m}Tc]sestamibi, 2-[{sup 18}F]fluoro-2-deoxyglucose ([{sup 18}F]FDG), and various {sup 3}H-labeled tracers. Two-dimensional scatter plots of [{sup 99m}Tc]sestamibi uptake/[{sup 18}F]FDG uptake show typical changes of known Pgp inhibitors including {sup 99}Tc1. The effects of {sup 99}Tc1 on the in vivo distribution of [{sup 99m}Tc]sestamibi and [{sup 18}F]FDG in rats also are comparable with the effects of verapamil, an established Pgp inhibitor and calcium channel blocker. We conclude that {sup 99/99m}Tc1 is a transport substrate and a potential inhibitor of Pgp. Our approach may be useful in the design of further radiotracers with specificity to Pgp.

Bergmann, R. E-mail: R.Bergmann@fz-rossendorf.de; Brust, P.; Scheunemann, M.; Pietzsch, H.-J.; Seifert, S.; Roux, F.; Johannsen, B

2000-02-01

51

Involvement of P-glycoprotein and multidrug resistance associated protein 1 on the transepithelial transport of a mercaptoacetamide-based histone-deacetylase inhibitor in Caco-2 cells.  

Science.gov (United States)

Oral bioavailability is one of the important criteria for development of a drug-lead candidate. In this study, the absorptive characteristics and the efflux mechanism of a mercaptoacetamide-based histone deacetyalse (HDAC) inhibitor, coded as W2, were investigated using Caco-2 cells. The transport of W2 was asymmetric as indicated by 1.85 fold higher basolateral to apical (BL to AP) than apical to basolateral (AP to BL) flux. Such asymmetry was associated with multidrug resistance associated protein 1 (MRP1) and P-glycoprotein (P-gp), as evidenced by specific inhibition of these proteins. In the presence of verapamil and cyclosporin A, potent inhibitors of P-gp, the apparent permeability ratio (P(app) BL to AP/P(app) AP to BL) of W2 was decreased from 1.85 to 0.73 and 1.03, respectively, and the absorption from apical to basolateral side was enhanced from 13.3+/-0.2x10(-6) cm/s to 17.3+/-0.12x10(-6) cm/s and 19+/-0.3x10(-6) cm/s, respectively. Upon addition of quinidine, a mixed P-gp and MRP1 inhibitor, the permeation of W2 from the apical side was significantly increased (P(app) 17.1+/-0.32x10(-6) cm/s) while the efflux was inhibited (P(app) 21.3+/-0.19x10(-6) cm/s). Furthermore, the influence of the MRP1 inhibitors, indomethacin and N-benzyl-indomethacin (NBI) was evaluated. NBI treatment attenuated the basolateral to apical flux of W2 (P(app) 20.3+/-0.1x10(-6) cm/s), whereas this effect was completely abrogated by indomethacin (P(app) 11+/-0.4x10(-6) cm/s). The results suggest that P-gp and MRP1 transporters are capable of mediating the efflux of W2 and might play a significant role in its oral absorption. PMID:19122284

Konsoula, Zacharoula; Jung, Mira

2009-01-01

52

Multidrug-resistance gene 1-type p-glycoprotein (MDR1 p-gp) inhibition by tariquidar impacts on neuroendocrine and behavioral processing of stress  

Science.gov (United States)

SUMMARY The multidrug-resistance gene 1-type p-glycoprotein (MDR1 p-gp) is a major gate-keeper at the blood-brain barrier (BBB), protecting the central nervous system from accumulation of toxic xenobiotics and drugs. In addition, MDR1 p-gp has been found to control the intracerebral access of glucocorticoid hormones and thus to modulate the activity of the hypothalamic-pituitary-adrenocortical (HPA) system. In view of the implication of glucocorticoids in the control of behavior, we examined how acute pharmacological inhibition of MDR1 p-gp at the BBB by tariquidar (XR9576; 12 mg/kg, PO) impacts on the neuroendocrine and behavioral processing of stress in C57BL/6JIcoHim inbred mice. Inhibition of MDR1 p-gp at the BBB did not alter emotional behavior at baseline. However, mice that were sensitized by water-avoidance stress, a mild psychological stressor, displayed significantly reduced anxiety-related behavior in the elevated plus-maze test when treated with tariquidar. Tariquidar, however, had no effect on stress-coping performance assessed in the forced swim test. Investigating the impact of acute MDR1 p-gp inhibition on the glucocorticoid system, we observed a significant attenuation of the mild stress-induced increase of plasma corticosterone after tariquidar administration. In order to examine whether the anti-anxiety effect of tariquidar in sensitized animals is mediated by glucocorticoids, the animals were treated with corticosterone (1 mg/kg, SC immediately after exposure to water-avoidance stress. Corticosterone caused a significant anxiolytic-like effect in this stress-related anxiety protocol, whereas tariquidar could not further enhance corticosterone’s anti-anxiety effects. The current data show for the first time that pharmacological inhibition of MDR1 p-gp at the murine BBB by tariquidar alters emotional behavior and HPA axis activity. By facilitating the entry of corticosterone into the brain, tariquidar enhances feedback inhibition of the HPA system and in this way improves anxiety-related stress processing. These findings highlight a novel approach to the treatment of stress-related affective disorders in humans. PMID:17881135

Thoeringer, Christoph K.; Wultsch, Thomas; Shahbazian, Anaid; Painsipp, Evelin; Holzer, Peter

2015-01-01

53

1-[4-(2-Aminoethoxy)phenylcarbonyl]-3,5-bis-(benzylidene)-4-oxopiperidines: A novel series of highly potent revertants of P-glycoprotein associated multidrug resistance  

OpenAIRE

The 1-[4-(2-aminoethoxy)phenylcarbonyl]-3,5-bis-(benzylidene)-4-oxopiperidines 5–8 are a novel cluster of highly potent P-glycoprotein dependent multidrug resistance (MDR) revertants. Using a concentration of 4 ?g/mL, these compounds possess 11–43 times the potency of verapamil in reversing MDR in murine L-5178 lymphoma cells transfected with the human MDR1 gene. Structure–activity relationships reveal that the attachment of the N-aroyl group to various 3,5-bis(benzylidene)-4-piperidon...

Das, Umashankar; Molna?r, Joseph; Bara?th, Zolta?n; Bata, Zsuzsanna; Dimmock, Jonathan R.

2008-01-01

54

The prognostic significance of P-glycoprotein, multidrug resistance-related protein 1 and lung resistance protein in pediatric acute lymphoblastic leukemia: a retrospective study of 295 newly diagnosed patients by the Children's Oncology Group.  

Science.gov (United States)

Multidrug resistance (MDR) is a phenomenon by which cells become resistant to an array of structurally unrelated chemotherapeutic agents. The prognostic value that P-glycoprotein (Pgp), multidrug resistance-related protein 1 (MRP1), and lung resistance protein (LRP) have in the setting of pediatric acute lymphoblastic leukemia (ALL) is controversial. In a retrospective study, we analyzed samples obtained from 295 similarly treated pediatric ALL patients to assess whether the overexpression and/or function of these proteins at diagnosis affects outcome. Most patients (70%, 207/295) did not overexpress an MDR protein. A small number of patients expressed functional Pgp (1%, 3/295) and some overexpressed functional MRP1 (10%, 19/295), with a statistically significant number of the latter being of T-lineage as opposed to pre-B (P overexpressed both Pgp and MRP1. Additional patients expressed increased levels of LRP. Elevated levels of these proteins at diagnosis did not correlate with risk factors and did not predict an adverse prognosis. Life-table estimates and Kaplan-Meier plots did not show any significant differences between patients who overexpressed an MDR protein compared with those who did not, nor was any difference noted when the different MDR + groups were compared with one another. These data strongly support the conclusion that the overexpression of these functional drug efflux pumps at diagnosis does not contribute to treatment failure in pediatric ALL. PMID:16019505

Olson, Douglas P; Taylor, Barbara J; La, Mei; Sather, Harland; Reaman, Gregory H; Ivy, S Percy

2005-05-01

55

Bivalent probes of the human multidrug transporter P-glycoprotein.  

Science.gov (United States)

A small library of bivalent agents was designed to probe the substrate binding sites of the human multidrug transporter P-glycoprotein (P-gp). The bivalent agents were composed of two copies of the P-gp substrate emetine, linked by tethers of varied composition. An optimum distance between the emetine molecules of approximately 10 A was found to be necessary for blocking transport of the known fluorescent substrate rhodamine 123. Additionally, it was determined that hydrophobic tethers were optimal for bridging the bivalent compounds; hydrophilic or cationic moieties within the tether had a detrimental effect on inhibition of transport. In addition to acting as probes of P-gp's drug binding sites, these agents were also potent inhibitors of P-gp. One agent, EmeC5, had IC50 values of 2.9 microM for inhibiting transport of rhodamine 123 and approximately 5 nM for inhibiting the binding of a known P-gp substrate, [125I]iodoarylazidoprazosin. Although EmeC5 is an inhibitor of P-gp and was shown to interact directly with P-gp in one or more of the substrate binding sites, our data suggest that it is either not a P-gp transport substrate itself or a poor one. Most significantly, EmeC5 was shown to reverse the MDR phenotype of MCF-7/DX1 cells when co-administered with a cytotoxic agent, such as doxorubicin. PMID:16981729

Pires, Marcos M; Hrycyna, Christine A; Chmielewski, Jean

2006-09-26

56

High-activity p-glycoprotein, multidrug resistance protein 2, and breast cancer resistance protein membrane vesicles prepared from transiently transfected human embryonic kidney 293-epstein-barr virus nuclear antigen cells.  

Science.gov (United States)

Membrane-bound transporter proteins play an important role in the efflux of drugs from cells and can significantly influence the pharmacokinetics of drug molecules. This study describes the production of large amounts of high-activity transporter membrane vesicles from human embryonic kidney 293-Epstein-Barr virus nuclear antigen cells transiently transfected using a Gateway-adapted pCEP4 plasmid. Transfections were scaled up to 10-liter cell cultures, and vesicle preparations were optimized using ultracentrifugation with a sucrose cushion, which enabled us to produce hundreds of milligrams of membrane vesicles expressing human efflux transporter proteins P-glycoprotein (P-gp)/multidrug resistance 1 (ABCB1), multidrug resistance protein 2 (MRP2) (ABCC2), and breast cancer resistance protein (BCRP) (ABCG2). Assays were developed and optimized for analyzing the ATP-dependent functionality of the transporters using probe substrates and specific inhibitors. Excellent signal/noise ratios of ATP-stimulated uptake for P-gp, MRP2, and BCRP vesicles were obtained, indicating high expression of functioning transporters. The uptake kinetics of the transporters was investigated by determining K(m) and V(max) using the model substrates N-methylquinidine (P-gp), estradiol-17beta-glucuronide (MRP2), and estrone-3-sulfate (BCRP). The ATP-dependent transport was inhibited by the model inhibitors verapamil (P-gp), benzbromarone (MRP2), and sulfasalazine (BCRP). The vesicles are thus well suited to screen for possible substrates and inhibitors in high throughput systems or are used for detailed mechanistic investigations of transporter kinetics of specific substances. PMID:20071452

Karlsson, Johan E; Heddle, Catherine; Rozkov, Aleksei; Rotticci-Mulder, Joke; Tuvesson, Ola; Hilgendorf, Constanze; Andersson, Tommy B

2010-04-01

57

Sanguinarine overcomes P-glycoprotein-mediated multidrug-resistance via induction of apoptosis and oncosis in CEM-VLB 1000 cells.  

Science.gov (United States)

Permeability-glycoprotein (Pgp) positive cells are known to be encoded by the multidrug-resistance gene (MDR1), and characterized by a reduced ability to accumulate drugs. The vinblastin-resistant, Pgp positive CEM-VLB 1000 and its wild type (Pgp-negative and vinblastin-sensitive) counterpart CEM-T4 human leukemia cells, when treated with the alkaloid sanguinarine, were both found to undergo apoptosis at concentrations of 1.5 microg/ml and oncosis/blister cell death (BCD) at concentrations of 12.5 microg/ml. The aim of this study was to assess the ability of sanguinarine to overcome Pgp-mediated multidrug-resistance (MDR), and also to characterize the cell death processes of apoptosis and oncosis (or bimodal cell death) induced by sanguinarine in MDR cells. The cell death processes of apoptosis and oncosis in CEM-VLB 1000 and CEM-T4 cell lines were found to be qualitatively similar when assessed by light microscopy, terminal deoxynucleotidyl transferase (TdT) end-labeling, annexin-V-binding, trypan blue exclusion and western blot analysis. Western blotting revealed an increase in the Bax/Bcl-2 ratio and activation of caspase-3 in apoptosis but not oncosis in both cell lines. The Pgp-positive CEM-VLB 1000 cells and their wild type CEM-T4 cells were both equally sensitive to sanguinarine. Thus, sanguinarine may overcome the phenomenon of Pgp-mediated MDR by inducing apoptosis through increasing the Bax/Bcl-2 ratio and activating caspase-3, and oncosis, which involved neither. PMID:16735106

Weerasinghe, Priya; Hallock, Sarathi; Tang, Shou-Ching; Trump, Benjamin; Liepins, Andrejs

2006-08-01

58

P-glycoproteins and other multidrug resistance transporters in the pharmacology of anthelmintics: Prospects for reversing transport-dependent anthelmintic resistance  

OpenAIRE

Parasitic helminths cause significant disease in animals and humans. In the absence of alternative treatments, anthelmintics remain the principal agents for their control. Resistance extends to the most important class of anthelmintics, the macrocyclic lactone endectocides (MLs), such as ivermectin, and presents serious problems for the livestock industries and threatens to severely limit current parasite control strategies in humans. Understanding drug resistance is important for optimizing ...

Lespine, Anne; Me?nez, Ce?cile; Bourguinat, Catherine; Prichard, Roger K.

2011-01-01

59

Multidrug resistance in small cell lung cancer: expression of P-glycoprotein, multidrug resistance protein 1 and lung resistance protein in chemo-naive patients and in relapsed disease.  

Science.gov (United States)

The aim of this study was to investigate the expression of multidrug resistance-associated proteins in metastatic small cell lung cancer (SCLC) cells correlated to cisplatin/etoposide chemotherapy response and the level of those proteins in relapsed disease. Samples were obtained by transbronchial fine needle aspiration biopsy (TBNA) of enlarged mediastinal lymph nodes in 17 patients. After cytological confirmation of SCLC, cells were stained by a panel of mAbs against internal epitopes of P-gp (JSB-1), MRP1 (MRPr1), LRP (LRP-56) and cytokeratin (MNF116) and analyzed by flow cytometry. We observed a significant negative correlation for better response rate to chemotherapy with individual expression of P-gp (r=-0.93, PLRP expression. P-gp and MRP1 expression was markedly increased in metastatic cells in four out of five patients with relapsed disease (4-12 months after starting chemotherapy), in comparison to their chemo-naive values. In conclusion, the results suggest that P-gp and MRP1 might be associated with SCLC cell survival during metastasis and chemotherapy, and that overexpression of those transporters in relapsed disease could assist short-term chemotherapy efficiency. PMID:16934363

Triller, Nadja; Korosec, Peter; Kern, Izidor; Kosnik, Mitja; Debeljak, Andrej

2006-11-01

60

P-glycoprotein mediates celecoxib-induced apoptosis in multiple drug-resistant cell lines.  

Science.gov (United States)

In several neoplastic diseases, including hepatocellular carcinoma, the expression of P-glycoprotein and cyclooxygenase-2 (COX-2) are often increased and involved in drug resistance and poor prognosis. P-glycoprotein, in addition to drug resistance, blocks cytochrome c release, preventing apoptosis in tumor cells. Because COX-2 induces P-glycoprotein expression, we evaluated the effect of celecoxib, a specific inhibitor of COX-2 activity, on P-glycoprotein-mediated resistance to apoptosis in cell lines expressing multidrug resistant (MDR) phenotype. Experiments were done using MDR-positive and parental cell lines at basal conditions and after exposure to 10 or 50 micromol/L celecoxib. We found that 10 micromol/L celecoxib reduced P-glycoprotein, Bcl-x(L), and Bcl-2 expression, and induced translocation of Bax from cytosol to mitochondria and cytochrome c release into cytosol in MDR-positive hepatocellular carcinoma cells. This causes the activation of caspase-3 and increases the number of cells going into apoptosis. No effect was shown on parental drug-sensitive or on MDR-positive hepatocellular carcinoma cells after transfection with MDR1 small interfering RNA. Interestingly, although inhibiting COX-2 activity, 50 micromol/L celecoxib weakly increased the expression of COX-2 and P-glycoprotein and did not alter Bcl-x(L) and Bcl-2 expression. In conclusion, these results show that relatively low concentrations of celecoxib induce cell apoptosis in MDR cell lines. This effect is mediated by P-glycoprotein and suggests that the efficacy of celecoxib in the treatment of different types of cancer may depend on celecoxib concentration and P-glycoprotein expression. PMID:17510421

Fantappiè, Ornella; Solazzo, Michela; Lasagna, Nadia; Platini, Francesca; Tessitore, Luciana; Mazzanti, Roberto

2007-05-15

61

Multidrug resistance in ocular melanoma.  

OpenAIRE

AIMS/BACKGROUND: Metastatic disease in patients with ocular melanoma is resistant to chemotherapy. One of the main mechanisms of modulating multidrug resistance is the expression of the multidrug resistance gene 1 (MDR1) product (p-glycoprotein) by tumour cells. The purpose of this study was to evaluate the frequency of expression of the MDR1 gene in ocular melanoma whose primary treatment was surgical excision or enucleation. METHODS: Twelve recent ocular melanomas were received fresh, snap ...

Mcnamara, M.; Clynes, M.; Dunne, B.; Nicamhlaoibh, R.; Lee, W. R.; Barnes, C.; Kennedy, S. M.

1996-01-01

62

Interrogation of multidrug resistance (MDR1) P-glycoprotein (ABCB1) expression in human pancreatic carcinoma cells: correlation of 99mTc-Sestamibi uptake with western blot analysis.  

Science.gov (United States)

Histopathological studies indicate that ?63% of pancreatic tumors express multidrug resistance (MDR1) P-glycoprotein (Pgp) and its polymorphic variants. However, Pgp expression detected at the mRNA or protein level does not always correlate with functional transport activity. Because Pgp transport activity is affected by specific mutations and the phosphorylation state of the protein, altered or less active forms of Pgp may also be detected by PCR or immunohistochemistry, which do not accurately reflect the status of tumor cell resistance. To interrogate the status of the functional expression of MDR1 Pgp in MiaPaCa-2 and PANC-1 cells, cellular transport studies using Tc-Sestamibi were performed and correlated with western blot analysis. Biochemical transport assays in human pancreatic carcinoma MiaPaCa-2 and PANC-1 cells, human epidermal carcinoma drug-sensitive KB-3-1 cells, and human breast carcinoma MCF-7 cells (negative controls), and human epidermal carcinoma drug-resistant KB-8-5 cells, human breast carcinoma stably transfected with Pgp MCF-7/MDR1Pgp cells, and liver carcinoma HepG2 cells (positive controls) were performed. Protein levels were determined using a monoclonal antibody C219. Tc-Sestamibi demonstrates accumulation in human pancreatic carcinoma MiaPaCa-2 and PANC-1 cells. Uptake profiles are not affected by treatment with LY335979, a Pgp inhibitor, and correlate with western blot analysis. These cellular transport studies indicate an absence of Pgp at a functional level in MiaPaCa-2 and PANC-1 cells. Because major pancreatic tumors originate from the pancreatic duct and Tc-Sestamibi undergoes a dominant hepatobiliary mode of excretion, it would not be a sensitive probe for imaging pancreatic adenocarcinomas. Following interrogation of the functional status of Pgp in other pancreatic carcinoma cells, chemotherapeutic drugs that are also MDR1 substrates could offer alternative therapeutics for treating pancreatic adenocarcinomas. PMID:25036383

Harpstrite, Scott E; Gu, Hannah; Natarajan, Radhika; Sharma, Vijay

2014-10-01

63

A novel hypothesis for the mechanism of action of P-glycoprotein as a multidrug transporter.  

Science.gov (United States)

For years, P-glycoprotein (P-gp) has been purported to be a membrane transporter capable of selectively transporting many (but not all) lipophilic anticancer drugs with diverse chemical structures. Because the alleged functions of P-gp provide a straightforward, near-perfect explanation for the molecular mechanism of multidrug resistance associated with P-gp overexpression. However, the exact molecular mechanism for P-gp's purported function has never been clearly understood since its initial discovery some 20 yr ago. In this paper, I develop a novel working hypothesis regarding the mechanism of P-gp's action and suggest that P-gp is an energy-dependent efflux pump only for certain conjugated metabolites (probably sulfates) of the lipophilic anticancer drugs but not for the parent compounds, as was always claimed. According to this hypothesis, P-gp overexpression in most cases is not the "culprit" but instead an "accomplice" in P-gp-associated multidrug resistance. The culprit is probably the enhanced function of the metabolizing enzymes for the lipophilic anticancer drugs. This hypothesis also predicts that one of the important physiological functions of P-gp is to be part of an intracellular machinery (together with the phase I and II metabolizing enzymes) for the metabolism, detoxification, and disposition of lipophilic endogenous chemicals as well as xenobiotics, including cytotoxic anticancer drugs. There exists a considerable body of circumstantial evidence in the literature that lends strong support to this mechanistic hypothesis of P-gp's action as well as to the predicted physiological functions of P-gp. It will be of considerable interest to examine this novel hypothesis experimentally. PMID:10331739

Zhu, B T

1999-05-01

64

Multiple efflux pumps are involved in the transepithelial transport of colchicine: combined effect of p-glycoprotein and multidrug resistance-associated protein 2 leads to decreased intestinal absorption throughout the entire small intestine.  

Science.gov (United States)

The purpose of this study was to thoroughly characterize the efflux transporters involved in the intestinal permeability of the oral microtubule polymerization inhibitor colchicine and to evaluate the role of these transporters in limiting its oral absorption. The effects of P-glycoprotein (P-gp), multidrug resistance-associated protein 2 (MRP2), and breast cancer resistance protein (BCRP) inhibitors on colchicine bidirectional permeability were studied across Caco-2 cell monolayers, inhibiting one versus multiple transporters simultaneously. Colchicine permeability was then investigated in different regions of the rat small intestine by in situ single-pass perfusion. Correlation with the P-gp/MRP2 expression level throughout different intestinal segments was investigated by immunoblotting. P-gp inhibitors [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 (GF120918), verapamil, and quinidine], and MRP2 inhibitors [3-[[3-[2-(7-chloroquinolin-2-yl)vinyl]phenyl]-(2-dimethylcarbamoylethylsulfanyl)methylsulfanyl] propionic acid (MK571), indomethacin, and p-aminohippuric acid (p-AH)] significantly increased apical (AP)-basolateral (BL) and decreased BL-AP Caco-2 transport in a concentration-dependent manner. No effect was obtained by the BCRP inhibitors fumitremorgin C (FTC) and pantoprazole. P-gp/MRP2 inhibitors combinations greatly reduced colchicine mucosal secretion, including complete abolishment of efflux (GF120918/MK571). Colchicine displayed low (versus metoprolol) and constant permeability along the rat small-intestine. GF120918 significantly increased colchicine permeability in the ileum with no effect in the jejunum, whereas MK571 augmented jejunal permeability without changing the ileal transport. The GF120918/MK571 combination caused an effect similar to that of MK571 alone in the jejunum and to that of GF120918 alone in the ileum. P-gp expression followed a gradient increasing from proximal to distal segments, whereas MRP2 decreased from proximal to distal small intestinal regions. Overall, it was revealed that the combined effect of P-gp and MRP2, but not BCRP, dominates colchicine transepithelial transport, leading to complete coverage of the entire small intestine, and makes the efflux transport dominate the intestinal permeability process. PMID:19589874

Dahan, Arik; Sabit, Hairat; Amidon, Gordon L

2009-10-01

65

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

Directory of Open Access Journals (Sweden)

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 ?m 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.

Cara Andrea

2007-03-01

66

Role of multidrug resistance in photodynamic therapy  

Science.gov (United States)

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.

Diddens, Heyke C.

1992-06-01

67

Usefulness of technetium-99m tetrofosmin liver imaging to detect hepatocellular carcinoma and related to expression of P-glycoprotein or multidrug resistance associated protein-a preliminary report  

International Nuclear Information System (INIS)

Technetium-99m Tetrofsomin (Tc-TF) has been shown to be useful in identifying several types of tumors, such as breast, lung, and thyroid cancers. There was no report in the literature for Tc-TF uptake in hepatocellular carcinoma (HCC). The aim of this study was to evaluate the usefulness of Tc-TF liver imaging to detect HCC and investigate the relationship between Tc-TF liver imaging findings and P-glycoprotein (Pgp) and multidrug resistance associated protein (MRP) expression. Before any therapy, 22 patients with HCC were enrolled in this study. Tc-TF liver images were performed l0 minutes after intravenous injection of 20mCi Tc-TF. All patients had liver biopsy or surgery within l week after Tc-TF liver imaging. Immunohistochemical study of the biopsy or resected HCC specimens was performed using anti-human Pgp and MRP antibodies. Twenty of the 22 (90.9%) patients showed negative Tc-TF liver imaging results without significant Tc-TF uptake in HCC, whereas only the remaining 2 (9.1%) patients showed positive Tc-TF liver imaging results with significant Tc-TF uptake in HCC. Positive Pgp expression was observed in 13 of 20 patients with negative Tc-TF liver imaging results, whereas positive MRP expression was observed in 6 of the remaining 7 patients with negative both Tc-TF liver imaging results and Pgp expression. However, negative Pgp expression but positive MRP expression was observed in all of the remaining 2 patients with positive Tc-TF liver imaging results. The positive Tc-TF liver imaging results. The correlation between Tc-TF liver imaging findings and Pgp expression was significant and better than between Tc-TF liver imaging findings and MRP expression. Pgp or MRP expression in HCC may induce no significant Tc-TF uptake in HCC resulting in negative Tc-TF liver imaging findings. Therefore, Tc-TF liver imaging is potential to be a non-invasive method to predict Pgp or MRP expression in HCC. However, further studies with a larger series of patients and longer follow-up time are necessary to confirm our findings

68

Modification by brefeldin A, bafilomycin A1 and 7-chloro-4-nitrobenz-2-oxa-1,3-diazole (NBD) of cellular accumulation and intracellular distribution of anthracyclines in the non-P-glycoprotein-mediated multidrug-resistant cell line COR-L23/R.  

OpenAIRE

We have investigated the effects of H(+)-ATPase inhibitors, bafilomycin A1 and 7-chloro-4-nitro-benz-2-oxa-1,3 diazole (NBD), and the Golgi inhibitor, brefeldin A, on daunorubicin accumulation and doxorubicin intracellular distribution in the non-P-glycoprotein-mediated multidrug-resistant cell line COR-L23/R. This cell line overexpress a 190 kDa protein which is probably the product of the MRP gene and shows an anthracycline accumulation defect and a drastically altered intracellular anthrac...

Rhodes, T.; Barrand, M. A.; Twentyman, P. R.

1994-01-01

69

Overexpression of lung resistance-related protein and P-glycoprotein and response to induction chemotherapy in acute myelogenous leukemia  

OpenAIRE

Lung resistance-related protein (LRP) and P-glycoprotein (P-gp) are associated with multidrug resistance. P-gp overexpression reduces intracellular anticancer drug concentrations and is correlated with low remission rates. However, whether the presence of LRP influences the response to induction chemotherapy remains controversial. Therefore, we investigated the relationship of LRP and P-gp overexpression with the response to induction chemotherapy. Univariate analysis revealed that there was ...

Toshiko Motoji; Hiroki Sugimori; Yan-Hua Wang; Minoko Takanashi; Tsuyoshi Odajima; Lee, Gabriel A.; Kazue Tsuji

2012-01-01

70

Increased expression of the multidrug transporter P-glycoprotein in limbic brain regions after amygdala-kindled seizures in rats.  

Science.gov (United States)

Increased expression of the multidrug transporter P-glycoprotein (Pgp; ABCB1) has previously been found in epileptogenic brain tissue from patients with pharmacoresistant temporal lobe epilepsy (TLE) as well as in the hippocampus and other limbic brain regions in the rat kainate model of TLE. Approaches to the quantification of Pgp expression have mainly been based on subjective visual estimation of the level of Pgp immunoreactivity in brain sections. In the present study, computer-assisted image analysis based on optical density (OD) measurements was used to examine immunohistochemical expression of Pgp in the kindling model of TLE. Sections from kainate-treated rats were used for comparison. Using diaminobenzidine as chromogen, Pgp was exclusively located in brain capillary endothelial cells, which was confirmed by double-labeling with an antibody against the endothelial glucose transporter (GLUT-1). After kainate-induced seizures, the intensity of endothelial Pgp staining significantly increased by 70-80% in the dentate gyrus. A significant, albeit less marked increase in Pgp expression in this area was also seen after amygdala-kindled seizures. Furthermore, Pgp was upregulated after kindling in the hilus of the dentate gyrus, the CA1 and CA3 sectors of the hippocampus, and the piriform and cerebral cortex. In kindled rats, most Pgp alterations occurred ipsilateral to the electrode in the basolateral amygdala. The data demonstrate that computer-assisted image analysis using OD is an accurate and rapid method to determine the relative amount of Pgp protein in brain sections and the effects of seizures on this multidrug transporter. The fact that Pgp overexpression in brain capillary endothelial cells occurs in two established models of difficult-to-treat TLE substantiates the notion that seizure-induced upregulation of Pgp contributes to multidrug resistance (MDR) in epilepsy. PMID:15066676

Volk, Holger A; Potschka, Heidrun; Löscher, Wolfgang

2004-01-01

71

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

Directory of Open Access Journals (Sweden)

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 clinical drug resistance.

FrancesJaneSharom

2014-03-01

72

Overcoming Multidrug Resistance in Human Cancer Cells by Natural Compounds  

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Full Text Available Multidrug resistance is a phenomenon whereby tumors become resistant to structurally unrelated anticancer drugs. P-glycoprotein belongs to the large ATP-binding cassette (ABC transporter superfamily of membrane transport proteins. P-glycoprotein mediates resistance to various classes of anticancer drugs including vinblastine, daunorubicin, and paclitaxel, by actively extruding the drugs from the cells. The quest for inhibitors of anticancer drug efflux transporters has uncovered natural compounds, including (--epigallocatechin gallate, curcumin, capsaicin, and guggulsterone, as promising candidates. In this review, studies on the effects of natural compounds on P-glycoprotein and anticancer drug efflux transporters are summarized.

Tomohiro Nabekura

2010-05-01

73

Inhibition of Multidrug Resistance-Linked P-Glycoprotein (ABCB1) Function by 5?-Fluorosulfonylbenzoyl 5?-Adenosine: Evidence for an ATP Analog That Interacts With Both Drug-Substrate- and Nucleotide-Binding Sites†  

OpenAIRE

5?-fluorosulfonylbenzonyl 5?-adenosine (FSBA) is an ATP analog that covalently modifies several residues in the nucleotide-binding domains (NBDs) of several ATPases, kinases and other proteins. P-glycoprotein (P-gp, ABCB1) is a member of the ATP-binding cassette (ABC) transporter superfamily that utilizes energy from ATP hydrolysis for the efflux of amphipathic anticancer agents from cancer cells. We investigated the interactions of FSBA with P-gp to study the catalytic cycle of ATP hydro...

Ohnuma, Shinobu; Chufan, Eduardo; Nandigama, Krishnamachary; Miller Jenkins, Lisa M.; Durell, Stewart R.; Appella, Ettore; Sauna, Zuben E.; Ambudkar, Suresh V.

2011-01-01

74

Cytokine-mediated reversal of multidrug resistance  

OpenAIRE

The occurrence of the multidrug resistance phenotype still represents a limiting factor for successful cancer chemotherapy. Numerous efforts have been made to develop strategies for reversal and/or modulation of this major therapy obstacle through targeting at different levels of intervention. The phenomenon of MDR is often associated with overexpression of resistance-associated genes. Since the classical type of MDR in human cancers is mainly mediated by the P-glycoprotein encoded by the mul...

Stein, Ulrike; Walther, Wolfgang

1998-01-01

75

Low-level doxorubicin resistance in P-glycoprotein-negative human pancreatic tumour PSN1/ADR cells implicates a brefeldin A-sensitive mechanism of drug extrusion.  

OpenAIRE

The human pancreatic tumour cell line PSN1/ADR, stepwise selected in 17-510 nM doxorubicin, displayed a multidrug resistance not conferred by P-glycoprotein (P-gp). Resistance to 17-51 nM doxorubicin was accompanied by overexpression of the vesicular marker lung resistance-related protein (LRP). Further selection in 170 nM doxorubicin led to the activation of multidrug resistance-associated protein (MRP) and to the development of drug accumulation/retention defects sensitive to verapamil. In ...

Verovski, V. N.; Den Berge, D. L.; Delvaeye, M. M.; Scheper, R. J.; Neve, W. J.; Storme, G. A.

1996-01-01

76

Inhibition of multidrug resistance-linked P-glycoprotein (ABCB1) function by 5'-fluorosulfonylbenzoyl 5'-adenosine: evidence for an ATP analogue that interacts with both drug-substrate-and nucleotide-binding sites.  

Science.gov (United States)

5'-Fluorosulfonylbenzonyl 5'-adenosine (FSBA) is an ATP analogue that covalently modifies several residues in the nucleotide-binding domains (NBDs) of several ATPases, kinases, and other proteins. P-glycoprotein (P-gp, ABCB1) is a member of the ATP-binding cassette (ABC) transporter superfamily that utilizes energy from ATP hydrolysis for the efflux of amphipathic anticancer agents from cancer cells. We investigated the interactions of FSBA with P-gp to study the catalytic cycle of ATP hydrolysis. Incubation of P-gp with FSBA inhibited ATP hydrolysis (IC(50 )= 0.21 mM) and the binding of 8-azido[?-(32)P]ATP (IC(50) = 0.68 mM). In addition, (14)C-FSBA cross-links to P-gp, suggesting that FSBA-mediated inhibition of ATP hydrolysis is irreversible due to covalent modification of P-gp. However, when the NBDs were occupied with a saturating concentration of ATP prior to treatment, FSBA stimulated ATP hydrolysis by P-gp. Furthermore, FSBA inhibited the photo-cross-linking of P-gp with [(125)I]iodoarylazidoprazosin (IAAP; IC(50) = 0.17 mM). As IAAP is a transport substrate for P-gp, this suggests that FSBA affects not only the NBDs but also the transport-substrate site in the transmembrane domains. Consistent with these results, FSBA blocked efflux of rhodamine 123 from P-gp-expressing cells. Additionally, mass spectrometric analysis identified FSBA cross-links to residues within or nearby the NBDs but not in the transmembrane domains, and docking of FSBA in a homology model of human P-gp NBDs supports the biochemical studies. Thus, FSBA is an ATP analogue that interacts with both the drug-binding and ATP-binding sites of P-gp, but fluorosulfonyl-mediated cross-linking is observed only at the NBDs. PMID:21452853

Ohnuma, Shinobu; Chufan, Eduardo; Nandigama, Krishnamachary; Jenkins, Lisa M Miller; Durell, Stewart R; Appella, Ettore; Sauna, Zuben E; Ambudkar, Suresh V

2011-05-10

77

Inhibition of Multidrug Resistance-Linked P-Glycoprotein (ABCB1) Function by 5?-Fluorosulfonylbenzoyl 5?-Adenosine: Evidence for an ATP Analog That Interacts With Both Drug-Substrate- and Nucleotide-Binding Sites†  

Science.gov (United States)

5?-fluorosulfonylbenzonyl 5?-adenosine (FSBA) is an ATP analog that covalently modifies several residues in the nucleotide-binding domains (NBDs) of several ATPases, kinases and other proteins. P-glycoprotein (P-gp, ABCB1) is a member of the ATP-binding cassette (ABC) transporter superfamily that utilizes energy from ATP hydrolysis for the efflux of amphipathic anticancer agents from cancer cells. We investigated the interactions of FSBA with P-gp to study the catalytic cycle of ATP hydrolysis. Incubation of P-gp with FSBA inhibited ATP hydrolysis (IC50= 0.21 mM) and the binding of 8-azido[?–32P]ATP (IC50= 0.68 mM). In addition, 14C-FSBA crosslinks to P-gp, suggesting that FSBA-mediated inhibition of ATP hydrolysis is irreversible due to covalent modification of P-gp. However, when the NBDs were occupied with a saturating concentration of ATP prior to treatment, FSBA stimulated ATP hydrolysis by P-gp. Furthermore, FSBA inhibited the photocrosslinking of P-gp with [125I]-Iodoaryl-azidoprazosin (IAAP; IC50 = 0.17 mM). As IAAP is a transport substrate for P-gp, this suggests that FSBA affects not only the NBDs, but also the transport-substrate site in the transmembrane domains. Consistent with these results, FSBA blocked efflux of rhodamine 123 from P-gp-expressing cells. Additionally, mass spectrometric analysis identified FSBA crosslinks to residues within or nearby the NBDs but not in the transmembrane domains and docking of FSBA in a homology model of human P-gp NBDs supports the biochemical studies. Thus, FSBA is an ATP analog that interacts with both the drug-binding and ATP-binding sites of P-gp, but fluorosulfonyl-mediated crosslinking is observed only at the NBDs. PMID:21452853

Ohnuma, Shinobu; Chufan, Eduardo; Nandigama, Krishnamachary; Miller Jenkins, Lisa M.; Durell, Stewart R.; Appella, Ettore; Sauna, Zuben E.; Ambudkar, Suresh V.

2011-01-01

78

Multi-drug resistance (MDR1) gene and P-glycoprotein influence on pharmacokinetic and pharmacodymanic of therapeutic drugs / Influência do gene de resistência múltipla (MDR1) e da P-glicoproteína na farmacocinética e farmacodinâmica de drogas terapêuticas  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese P-glicoproteína (P-gp) é um transportador de membrana ligado ao gene de resistência múltipla (MDR1), expressado em células tumorais e também em tecidos normais como intestino, fígado, rins, membranas hematoencefálica, hemo-placentária e medula espinhal. A P-gp já foi identificada em camundongos, rat [...] os, bovinos, macacos, roedores e seres humanos e tem ganhado relevância clínica particular em função de sua expressão limitar o acesso de drogas ao cérebro e interferir com a absorção intestinal quando administradas pela via oral. Esta proteína participa da função protetora do organismo contra uma grande variedade de substratos, evitando a entrada de drogas no sistema nervoso central. A P-gp interfere também com a biodisponibilidade dos fármacos, incluindo absorção, distribuição, metabolização e excreção, influenciando assim, a farmacocinética e dinâmica dos mesmos. Desta maneira, a modulação da P-gp pode explicar alguns efeitos adversos no sistema nervoso central, induzidos por alguns fármacos após administração intravenosa, e a pobre resposta após administração oral em pacientes. A alteração na expressão ou função da P-glicoproteína tem sido associada a uma maior susceptibilidade a diversas doenças em humanos e animais. Estudos adicionais relacionados à expressão e à função da P-gp espécie-específica têm implicação clínica importante em termos de eficiência de tratamento. Abstract in english (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 t [...] his 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.

Renata Lehn, Linardi; Cláudio Corrêa, Natalini.

2006-02-01

79

Expression of P-glycoprotein, multidrug resistance-associated protein, glutathione-S-transferase pi and p53 in canine transmissible venereal tumor / Expressão da glicoproteína-P, proteína associada à múltiplas drogas, glutationa-S-transferase pi e p53 no tumor venéreo transmissível canino  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese A superexpressão das proteínas glicoproteína-P (Gp-P), proteína associada à resistência à múltiplas drogas 1 (MRP1) e p53 mutante e a enzima glutationa-S-transferase pi (GSTpi) está relacionada com resistência à quimioterapia em neoplasias humanas e caninas. Este estudo avaliou a expressão, por meio [...] da imuno-histoquímica desses marcadores em espécimes de TVT caninos sem histórico de quimioterapia prévia (TVT1, n=9) e em TVT caninos que apresentaram resposta clínica insatisfatória ao sulfato de vincristina (TVT2, n=5). A porcentagem de espécimes positivos para Gp-P, MRP1, GSTpi e p53 foram, respectivamente 88,8%, 0%, 44,5% e 22,2% no grupo TVT1 e 80%, 0%, 80% e 0% no grupo TVT2. No TVT1, um espécime apresentou expressão positiva para três marcadores e quatro para dois marcadores. No TVT2, três espécimes expressaram a Gp-P e GSTpi. Em conclusão, os TVTs caninos estudados expressaram os quatro marcadores avaliados, no entanto apenas a Gp-P e GSTpi foram significativamente expressas, principalmente no citoplasmas e no citoplasma e no núcleo, respectivamente, tanto antes da quimioterapia quanto após à exposição ao sulfato de vincristina. Estudos futuros são necessários para demonstrar a função desses dois marcadores em conferir resistência à multiplas drogas (RMD) ou predizer a resposta a quimioterapia no TVT canino. Abstract in english 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 t [...] wo 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.

Daniel G., Gerardi; Mirela, Tinucci-Costa; Ana Carolina T., Silveira; Juliana V., Moro.

2014-01-01

80

Inhibition of P-glycoprotein by two artemisinin derivatives  

OpenAIRE

P-Glycoprotein/MDR1 represents an important component of the blood brain barrier and contributes to multidrug resistance. We investigated two derivatives of the anti-malarial artemisinin, SM616 and GHP-AJM-3/23, concerning their ability to interact with P-glycoprotein. The ability of the two compounds to inhibit P-glycoprotein (P-gp) activity was examined in sensitive CCRF-CEM and P-gp over-expressing and multidrug-resistant CEM/ADR5000 cells as well as in porcine brain capillary endothelial ...

Steglich, Babette; Mahringer, Anne; Li, Ying; Posner, Gary H.; Fricker, Gert; Efferth, Thomas

2012-01-01

81

Synthesis of 5-oxyquinoline derivatives for reversal of multidrug resistance  

OpenAIRE

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...

Torsten Dittrich; Nils Hanekop; Nacera Infed; Lutz Schmitt; Manfred Braun

2012-01-01

82

BRCA2-Deficient Sarcomatoid Mammary Tumors Exhibit Multidrug Resistance.  

Science.gov (United States)

Pan- or multidrug resistance is a central problem in clinical oncology. Here, we use a genetically engineered mouse model of BRCA2-associated hereditary breast cancer to study drug resistance to several types of chemotherapy and PARP inhibition. We found that multidrug resistance was strongly associated with an EMT-like sarcomatoid phenotype and high expression of the Abcb1b gene, which encodes the drug efflux transporter P-glycoprotein. Inhibition of P-glycoprotein could partly resensitize sarcomatoid tumors to the PARP inhibitor olaparib, docetaxel, and doxorubicin. We propose that multidrug resistance is a multifactorial process and that mouse models are useful to unravel this. Cancer Res; 75(4); 732-41. ©2014 AACR. PMID:25511378

Jaspers, Janneke E; Sol, Wendy; Kersbergen, Ariena; Schlicker, Andreas; Guyader, Charlotte; Xu, Guotai; Wessels, Lodewyk; Borst, Piet; Jonkers, Jos; Rottenberg, Sven

2015-02-15

83

Elacridar enhances the cytotoxic effects of sunitinib and prevents multidrug resistance in renal carcinoma cells.  

Science.gov (United States)

Intrinsic drug resistance occurs in many renal carcinomas and is associated with increased expression of multidrug resistant proteins, which inhibits intracellular drug accumulation. Multidrug resistant protein 1, also known as P-glycoprotein, is a membrane drug efflux pump belonging to the ATP-binding cassette (ABC) transporter superfamily. ABC Sub-family B Member 2 (ABCG2) is widely distributed and is involved in the multidrug resistant phenotype. Sunitinib is a tyrosine kinase inhibitor used to treat kidney cancer that disrupts signaling pathways responsible for abnormal cancer cell proliferation and tumor angiogenesis. Multiple drug resistance is important in tyrosine kinase inhibitor-induced resistance. We hypothesized that inhibition of multidrug resistant transporters by elacridar (dual inhibitor of P-glycoprotein and ABCG 2) might overcome sunitinib resistance in experimental renal cell carcinoma. Human renal carcinoma cell lines 786-O, ACHN, and Caki-1 were treated with sunitinib or elacridar alone, or in combination. We showed that elacridar significantly enhanced sunitinib cytotoxicity in 786-O cells. P-glycoprotein activity, confirmed by P-glycoprotein function assay, was found to be inhibited by elacridar. ABCG2 expression was low in all renal carcinoma cell lines, and was suppressed only by combination treatment in 786-O cells. ABCG2 function was inhibited by sunitinib alone or combination with elacridar but not elacridar alone. These findings suggest that sunitinib resistance involves multidrug resistance transporters, and in combination with elacridar, can be reversed in renal carcinoma cells by P-glycoprotein inhibition. PMID:25455500

Sato, Hiromi; Siddig, Sana; Uzu, Miaki; Suzuki, Sayumi; Nomura, Yuki; Kashiba, Tatsuro; Gushimiyagi, Keisuke; Sekine, Yuko; Uehara, Tomoya; Arano, Yasushi; Yamaura, Katsunori; Ueno, Koichi

2015-01-01

84

Multidrug resistance in Lactococcus lactis: evidence for ATP-dependent drug extrusion from the inner leaflet of the cytoplasmic membrane.  

OpenAIRE

Lactococcus lactis possesses an ATP-dependent drug extrusion system which shares functional properties with the mammalian multidrug resistance (MDR) transporter P-glycoprotein. One of the intriguing aspects of both transporters is their ability to interact with a broad range of structurally unrelated amphiphilic compounds. It has been suggested that P-glycoprotein removes drugs directly from the membrane. Evidence is presented that this model is correct for the lactococcal multidrug transport...

Bolhuis, H.; Veen, H. W.; Molenaar, D.; Poolman, B.; Driessen, A. J.; Konings, W. N.

1996-01-01

85

Multidrug-Resistant Tuberculosis  

Centers for Disease Control (CDC) Podcasts

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.

2008-10-28

86

Multidrug-resistant tuberculosis  

OpenAIRE

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 i...

McNerney Ruth; Zager Ellen M

2008-01-01

87

Reversal of P-glycoprotein-dependent resistance to vinblastine by newly synthesized bisbenzylisoquinoline alkaloids in mouse leukemia P388 cells.  

Science.gov (United States)

We examined the ability of partially synthesized new compounds from fangchinoline and tetrandrine to reverse P-glycoprotein (P-gp)-dependent multidrug resistance (MDR) in vitro and in vivo. All compound enhanced the in vitro cyctotoxic effect of vinblastin (VBL) at 0.1 microM as potent as 10 microM verapamil against the resistant cell line P388/ADR. The combination effect tended to be strong by substitution of bulky group, resulting 5,14-dibromotetrandrine (compound #9) showed the strongest effect. Compound #9 increased intracellular VBL accumulation in P388/ADR cells, much stronger than verapamil, as well as cytotoxic combined effect. This mechanism seems to inhibit the function of P-gp, but not the expression of P-gp. In combination with VBL, this compound also synergistically prolonged the life-span of P388/ADR-bearing mice. Bisbenzylisoquinoline alkaloids and their derivatives are possible to be good candidates as modifier of MDR in cancer chemotherapy. PMID:16204959

Wang, Feng-Peng; Wang, Li; Yang, Jin-Song; Nomura, Masaaki; Miyamoto, Ken-Ichi

2005-10-01

88

Multidrug resistant Acinetobacter  

Directory of Open Access Journals (Sweden)

Full Text Available Emergence and spread of Acinetobacter species, resistant to most of the available antimicrobial agents, is an area of great concern. It is now being frequently associated with healthcare associated infections. Literature was searched at PUBMED, Google Scholar, and Cochrane Library, using the terms ?Acinetobacter Resistance, multidrug resistant (MDR, Antimicrobial Therapy, Outbreak, Colistin, Tigecycline, AmpC enzymes, and carbapenemases in various combinations. The terms such as MDR, Extensively Drug Resistant (XDR, and Pan Drug Resistant (PDR have been used in published literature with varied definitions, leading to confusion in the correlation of data from various studies. In this review various mechanisms of resistance in the Acinetobacter species have been discussed. The review also probes upon the current therapeutic options, including combination therapies available to treat infections due to resistant Acinetobacter species in adults as well as children. There is an urgent need to enforce infection control measures and antimicrobial stewardship programs to prevent the further spread of these resistant Acinetobacter species and to delay the emergence of increased resistance in the bacteria.

Manchanda Vikas

2010-01-01

89

Overexpression of lung resistance-related protein and P-glycoprotein and response to induction chemotherapy in acute myelogenous leukemia.  

Science.gov (United States)

Lung resistance-related protein (LRP) and P-glycoprotein (P-gp) are associated with multidrug resistance. P-gp overexpression reduces intracellular anticancer drug concentrations and is correlated with low remission rates. However, whether the presence of LRP influences the response to induction chemotherapy remains controversial. Therefore, we investigated the relationship of LRP and P-gp overexpression with the response to induction chemotherapy. Univariate analysis revealed that there was a significant difference between complete remission rates for acute myelogenous leukemia patients depending on their blast cell expressions, between LRP positive versus negative, P-gp positive versus negative, and LRP/P-gp double positive versus other groups. Crude odds ratios (ORs) for complete remission were 0.390, 0.360, and 0.307 for LRP positive, for P-gp positive, and LRP/P-gp double positive patients, respectively. After controlling the confounding variables by stepwise multivariate logistical regression analysis, the presence of LRP/P-gp double positivity and P-gp positivity were found to be independent prognostic factors; adjusted ORs were 0.233 and 0.393, respectively. Furthermore, the monoclonal antibody against LRP significantly increased daunorubicin acumulation (P=0.004) in the nuclei of leukemic blast cells with LRP positivity in more than 10% of the cells. An LRP reversing agent, PAK-104P, was found to increase the daunorubicin content with marginal significance (P=0.060). The present results suggest that not only the presence of P-gp, but also LRP in leukemic blast cells is a risk factor for resistance to induction chemotherapy. Inhibiting LRP function, similar to the inhibition of P-gp function, will be necessary to improve the effectiveness of induction chemotherapy. PMID:23087807

Tsuji, Kazue; Wang, Yan-Hua; Takanashi, Minoko; Odajima, Tsuyoshi; Lee, Gabriel A; Sugimori, Hiroki; Motoji, Toshiko

2012-07-11

90

Overexpression of lung resistance-related protein and P-glycoprotein and response to induction chemotherapy in acute myelogenous leukemia  

Directory of Open Access Journals (Sweden)

Full Text Available Lung resistance-related protein (LRP and P-glycoprotein (P-gp are associated with multidrug resistance. P-gp overexpression reduces intracellular anticancer drug concentrations and is correlated with low remission rates. However, whether the presence of LRP influences the response to induction chemotherapy remains controversial. Therefore, we investigated the relationship of LRP and P-gp overexpression with the response to induction chemotherapy. Univariate analysis revealed that there was a significant difference between complete remission rates for acute myelogenous leukemia patients depending on their blast cell expressions, between LRP positive versus negative, P-gp positive versus negative, and LRP/P-gp double positive versus other groups. Crude odds ratios (ORs for complete remission were 0.390, 0.360, and 0.307 for LRP positive, for P-gp positive, and LRP/P- gp double positive patients, respectively. After controlling the confounding variables by stepwise multivariate logistical regression analysis, the presence of LRP/P-gp double positivity and P-gp positivity were found to be independent prognostic factors; adjusted ORs were 0.233 and 0.393, respectively. Furthermore, the monoclonal antibody against LRP significantly increased daunorubicin acumulation (P=0.004 in the nuclei of leukemic blast cells with LRP positivity in more than 10% of the cells. An LRP reversing agent, PAK-104P, was found to increase the daunorubicin content with marginal significance (P=0.060. The present results suggest that not only the presence of P-gp, but also LRP in leukemic blast cells is a risk factor for resistance to induction chemotherapy. Inhibiting LRP function, similar to the inhibition of P-gp function, will be necessary to improve the effectiveness of induction chemotherapy.

Toshiko Motoji

2012-07-01

91

Reversal of P-glycoprotein-mediated paclitaxel resistance by new synthetic isoprenoids in human bladder cancer cell line.  

Science.gov (United States)

We isolated a paclitaxel-resistant cell line (KK47/TX30) from a human bladder cancer cell line (KK47/WT) in order to investigate the mechanism of and reversal agents for paclitaxel resistance. KK47/TX30 cells exhibited 700-fold resistance to paclitaxel and cross-resistance to vinca alkaloids and topoisomerase II inhibitors. Tubulin polymerization assay showed no significant difference in the ratio of polymerized alpha- and beta-tubulin between KK47/WT and KK47/TX30 cells. Western blot analysis demonstrated overexpression of P-glycoprotein (P-gp) and lung resistance-related protein (LRP) in KK47/TX30 cells. Drug accumulation and efflux studies showed that the decreased paclitaxel accumulation in KK47/TX30 cells was due to enhanced paclitaxel efflux. Cell survival assay revealed that verapamil and cepharanthine, conventional P-gp modulators, could completely overcome paclitaxel resistance. To investigate whether new synthetic isoprenoids could overcome paclitaxel resistance, we synthesized 31 isoprenoids based on the structure of N-solanesyl-N,N'-bis(3,4-dimethoxybenzyl)ethylenediamine (SDB), which could reverse multidrug resistance (MDR), as shown previously. Among those examined, trans-N,N'-bis(3,4-dimethoxybenzyl)-N-solanesyl-1,2-diaminocyclohexane (N-5228) could completely reverse paclitaxel resistance in KK47/TX30 cells. N-5228 inhibited photoaffinity labeling of P-gp by [(3)H]azidopine, suggesting that N-5228 could bind to P-gp directly and could be a substrate of P-gp. Next, we investigated structural features of these 31 isoprenoids in order to determine the structural requirements for the reversal of P-gp-mediated paclitaxel resistance, suggesting that the following structural features are important for overcoming paclitaxel resistance: (1) a basic structure of 8 to 10 isoprene units, (2) a cyclohexane ring or benzene ring within the framework, (3) two cationic sites in close proximity to each other, and (4) a benzyl group with 3,4-dimethoxy functionalities, which have moderate electron-donating ability. These findings may provide valuable information for the development of P-gp-mediated MDR-reversing agents. PMID:12359058

Enokida, Hideki; Gotanda, Takenari; Oku, Shoichi; Imazono, Yoshiharu; Kubo, Hiroyuki; Hanada, Toshikatsu; Suzuki, Shigenori; Inomata, Kouhei; Kishiye, Takao; Tahara, Yoshiyuki; Nishiyama, Kenryu; Nakagawa, Masayuki

2002-09-01

92

Clinical imaging of multidrug resistance in cancer  

Energy Technology Data Exchange (ETDEWEB)

The most well-characterized mechanism of multidrug resistance (MDR) involves P-glycoprotein (Pgp), a transmembrane protein acting as an ATP-dependent drug efflux pump. The recognition of {sup 9}9mTc-Sestamibi and other lipophilic cations as transport substrates for Pgp provided the necessary tool for the clinical assessment of Pgp function in patients with cancer. Many clinical studies from different institutions and trials including variety of malignancies indicate that both tumor uptake and clearance of {sup 9}9mTc-Sestamibi are correlate with Pgp expression and may be used for the phenotypic assessment of multidrug resistance. Although both parameters may predict tumor responsible to chemotherapy, the extraction of efflux rate constants appeared o provide a more direct index of Pgp function as compared tp tracer uptake ratio allowing to trace a continuous spectrum of drug transport activity. Preliminary studies the use of MDR imaging agents to monitor the modulating ability of revertant compounds. Although the results support the feasibility of this approach, the alteration of tracer pharmacokinetics induced by the modulators certainly constitute a challenge in the development of a simple functional test suitable in clinical practice. The extension of the acquired imaging methodology to tumors with redundant intrinsic resistant mechanism. Due to multifactorial nature of phenomenon, the development of new tracers with substrate specificity for other known the complex array of cellular mechanisms contributing to treatment failure.

Del Vecchi, S.; Ciarmiello, A.; Salvatore, M. [Naples Univ. Federico 2. (Italy). Medicina Nucleare. Dipt. di Scienze Biomorfologiche e Funzionali

1999-06-01

93

Clinical imaging of multidrug resistance in cancer  

International Nuclear Information System (INIS)

The most well-characterized mechanism of multidrug resistance (MDR) involves P-glycoprotein (Pgp), a transmembrane protein acting as an ATP-dependent drug efflux pump. The recognition of 99mTc-Sestamibi and other lipophilic cations as transport substrates for Pgp provided the necessary tool for the clinical assessment of Pgp function in patients with cancer. Many clinical studies from different institutions and trials including variety of malignancies indicate that both tumor uptake and clearance of 99mTc-Sestamibi are correlate with Pgp expression and may be used for the phenotypic assessment of multidrug resistance. Although both parameters may predict tumor responsible to chemotherapy, the extraction of efflux rate constants appeared o provide a more direct index of Pgp function as compared tp tracer uptake ratio allowing to trace a continuous spectrum of drug transport activity. Preliminary studies the use of MDR imaging agents to monitor the modulating ability of revertant compounds. Although the results support the feasibility of this approach, the alteration of tracer pharmacokinetics induced by the modulators certainly constitute a challenge in the development of a simple functional test suitable in clinical practice. The extension of the acquired imaging methodology to tumors with redundant intrinsic resistant mechanism. Due to multifactorial nature of phenomenon, the development of new tracers with substrate specificity for other known ith substrate specificity for other known the complex array of cellular mechanisms contributing to treatment failure

94

Synthesis of 5-oxyquinoline derivatives for reversal of multidrug resistance  

Directory of Open Access Journals (Sweden)

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.

Torsten Dittrich

2012-10-01

95

The "specific" P-glycoprotein inhibitor Tariquidar is also a substrate and an inhibitor for breast cancer resistance protein (BCRP/ABCG2).  

Science.gov (United States)

Tariquidar was developed as a specific inhibitor of the efflux transporter ABCB1. Recent positron emission tomographic brain imaging studies using [(11)C]tariquidar to measure ABCB1 (P-gp, P-glycoprotein) density in mice indicate that the inhibitor may not be as specific as previously thought. We examined its selectivity as an inhibitor and a substrate for the human transporters P-gp, breast cancer resistance protein (BCRP, ABCG2), and multidrug resistance protein 1 (MRP1, ABCC1). Our results show that at low concentrations, tariquidar acts selectively as an inhibitor of P-gp and also as a substrate of BCRP. At much higher concentrations (?100 nM), tariquidar acts as an inhibitor of both P-gp and BCRP. Thus, the in vivo specificity of tariquidar depends on concentration and the relative density and capacity of P-gp vs BCRP. PMID:22778859

Kannan, Pavitra; Telu, Sanjay; Shukla, Suneet; Ambudkar, Suresh V; Pike, Victor W; Halldin, Christer; Gottesman, Michael M; Innis, Robert B; Hall, Matthew D

2011-02-16

96

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

Directory of Open Access Journals (Sweden)

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.

Di Pietro A.

1999-01-01

97

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english 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 dom [...] ain 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.

A., Di Pietro; G., Dayan; G., Conseil; E., Steinfels; T., Krell; D., Trompier; H., Baubichon-Cortay; J.-M., Jault.

1999-08-01

98

Multidrug-resistant tuberculosis  

Directory of Open Access Journals (Sweden)

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 that inclusion of population based statistics in global surveillance data is necessary to better inform debate on the control of drug resistant tuberculosis. Summary Re-appraisal of global MDR-TB data to include population based statistics suggests that the problem of drug resistant tuberculosis in sub-Saharan Africa is more critical than previously perceived.

McNerney Ruth

2008-01-01

99

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese 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. Est [...] udos de mecanismos de resistência múltipla 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 da linhagem eritro-leucêmica K562. Esta linhagem celular, denominada Lucena 1, super-expressa a glicoproteína P e tem sua resistência revertida pelos quimio-sensibilizantes verapamil, trifluoperazina e ciclosporinas A, D e G. Ademais, demonstramos que o azul de metileno era capaz de reverter parcialmente a resistência nesta linhagem celular. Em contraste, o uso de 5-flúor-uracil aumentava a resistência de Lucena 1. Adicionalmente aos quimioterápicos, células Lucena 1 eram resistentes radiação ultra-violeta A e peróxido de hidrogênio e deixavam de mobilizar o cálcio intra-celular quando se usava tapsigargina. Mudanças no cito-esqueleto desta linhagem foram também observadas. Abstract in english 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 multidr [...] ug 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.

VIVIAN M., RUMJANEK; GILMA S., TRINDADE; KAREN, WAGNER-SOUZA; MICHELE C., MELETTI-DE-OLIVEIRA; LUIS F., MARQUES-SANTOS; RAQUEL C., MAIA; MÁRCIA A. M., CAPELLA.

2001-03-01

100

A P-glycoprotein homologue of Plasmodium falciparum is localized on the digestive vacuole  

OpenAIRE

Resistance to chloroquine in Plasmodium falciparum bears a striking similarity to the multi-drug resistance (MDR) phenotype of mammalian tumor cells which is mediated by overexpression of P-glycoprotein. We show here that the P. falciparum homologue of the P-glycoprotein (Pgh1) is a 160,000-D protein that is expressed throughout the asexual erythrocytic life cycle of the parasite. Quantitative immunoblotting analysis has shown that the protein is expressed at approximately equal levels in chl...

1991-01-01

101

Kinetic Validation of the Models for P-Glycoprotein ATP Hydrolysis and Vanadate-Induced Trapping. Proposal for Additional Steps  

OpenAIRE

P-Glycoprotein, a member of the ATP-binding cassette (ABC) superfamily, is a multidrug transporter responsible for cellular efflux of hundreds of structurally unrelated compounds, including natural products, many clinically used drugs and anti-cancer agents. Expression of P-glycoprotein has been linked to multidrug resistance in human cancers. ABC transporters are driven by ATP hydrolysis at their two cytoplasmic nucleotide-binding domains, which interact to form a closed ATP-bound sandwich d...

Lugo, Miguel Ramo?n; Sharom, Frances Jane

2014-01-01

102

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

OpenAIRE

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 ancil...

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

2013-01-01

103

Primary multidrug resistant tuberculosis  

Directory of Open Access Journals (Sweden)

Full Text Available A 37-year old man presented at our institution with back pain, low-grade fever and weight-loss. X-ray of chest (postero-anterior view showed multiple opacities with erosion of right 2nd and left 6th ribs. CT-scan of thorax and CT-guided FNAC con-firmed the diagnosis of tuberculosis of ribs. Even after 5-months of treatment with four first line drugs, the patient developed a cold abscess at the back. Mycobacterial culture and drug sensitivity of material aspirated by Radiometric method from the cold abscess showed growth of Mycobacterium tuberculosis, and those bacilli were resistant to both isoniazide and rifampicin. The patient did not have anti-tubercu-lar medication in the past, and that established the diagnosis of primary multidrug resistant tuberculosis of ribs. Patient was treated successfully with 2nd line drugs at the cost of moderate degree of hearing loss. After one and half years of treatment X-ray of chest (PA view showed complete healing of rib erosions with new bone formation.

Sarkar Supriya

2007-01-01

104

Multidrug-resistant tuberculosis.  

Science.gov (United States)

Despite the efforts made worldwide to reduce the number of cases of drug-susceptible tuberculosis, multidrug-resistant tuberculosis (MDR-TB) constitutes an important public health issue. Around 440,000 new cases of MDR-TB are estimated annually, although in 2008 only 7% of these (29,423 cases) were notified. The laboratory tests for diagnosing resistance may be phenotypic (based on culture growth in the presence of drugs) or genotypic (i.e. identification of the presence of mutations that confer resistance). The urgent need for a rapid means of detecting resistance to anti-TB drugs has resulted in the development of many genotypic methods over recent years. The treatment of MDR-TB is expensive, complex, prolonged (18-24 months) and associated with a higher incidence of adverse reactions. Some basic principles must be observed when prescribing an adequate treatment regimen for MDR-TB: (a) the association of at least four drugs (three of which should not have been used previously); (b) use of a fluoroquinolone; and (c) use of an injectable anti-TB drug. In Brazil, the therapeutic regimen for MDR-TB has been standardized and consists of five drugs: terizidone, levofloxacin, pyrazinamide, ethambutol and an aminoglycoside (streptomycin or amikacin). Pulmonary resection is an important tool in the coadjuvant treatment of MDR-TB. While a recent meta-analysis revealed an average cure rate of MDR-TB of 69%, clinical studies are currently being conducted with new drugs and with drugs already available on the market but with a new indication for TB, with encouraging results that will enable more effective treatment regimens to be planned in the future. PMID:23477764

Lemos, Antônio Carlos Moreira; Matos, Eliana Dias

2013-01-01

105

Multidrug-resistant tuberculosis  

Directory of Open Access Journals (Sweden)

Full Text Available Despite the efforts made worldwide to reduce the number of cases of drug-susceptible tuberculosis, multidrug-resistant tuberculosis (MDR-TB constitutes an important public health issue. Around 440,000 new cases of MDR-TB are estimated annually, although in 2008 only 7% of these (29,423 cases were notified. The laboratory tests for diagnosing resistance may be phenotypic (based on culture growth in the presence of drugs or genotypic (i.e. identification of the presence of mutations that confer resistance. The urgent need for a rapid means of detecting resistance to anti-TB drugs has resulted in the development of many genotypic methods over recent years. The treatment of MDR-TB is expensive, complex, prolonged (18-24 months and associated with a higher incidence of adverse reactions. Some basic principles must be observed when prescribing an adequate treatment regimen for MDR-TB: (a the association of at least four drugs (three of which should not have been used previously; (b use of a fluoroquinolone; and (c use of an injectable anti-TB drug. In Brazil, the therapeutic regimen for MDR-TB has been standardized and consists of five drugs: terizidone, levofloxacin, pyrazinamide, ethambutol and an aminoglycoside (streptomycin or amikacin. Pulmonary resection is an important tool in the coadjuvant treatment of MDR-TB. While a recent meta-analysis revealed an average cure rate of MDR-TB of 69%, clinical studies are currently being conducted with new drugs and with drugs already available on the market but with a new indication for TB, with encouraging results that will enable more effective treatment regimens to be planned in the future.

Antônio Carlos Moreira Lemos

2013-04-01

106

Transmembrane domain (TM) 9 represents a novel site in P-glycoprotein that affects drug resistance and cooperates with TM6 to mediate [125I]iodoarylazidoprazosin labeling.  

Science.gov (United States)

The multidrug resistant cell line DC-3F/ADII was obtained by stepwise selection for growth in actinomycin D (ActD). Compared with parental cells, it displays high resistance to ActD and vincristine and low resistance to colchicine and daunorubicin. These cells overexpress a form of P-glycoprotein (Pgp1) containing a double mutation, I837L and N839I, in transmembrane domain (TM) 9; when transfected into DC-3F, this mutation confers the DC-3F/ADII phenotype. We have shown previously that another cell line, DC-3F/ADX, also displays this phenotype and overexpresses a mutant form of Pgp1 containing a double mutation in TM6 (G338A, A339P). Hence, mutations in TM9 and TM6 are independently capable of conferring the same cross-resistance phenotype. The TM6 mutations inhibit the ability of cyclosporin A to reverse cross-resistance and to block labeling of the protein by [125I]iodoarylazidoprazosin (IAAP), whereas the TM9 mutations do not show similar effects. A chimeric protein containing both pairs of mutations confers twice the level of resistance to ActD than expected from the sum of the individual mutations, but it cannot be labeled to detectable levels with [125I]IAAP. Thus, TM9 represents a novel site that cooperates with TM6 to mediate drug resistance and [125I]IAAP labeling. PMID:11455011

Song, J; Melera, P W

2001-08-01

107

An atomic detail model for the human ATP binding cassette transporter P-glycoprotein derived from disulfide cross-linking and homology modeling.  

OpenAIRE

The multidrug resistance P-glycoprotein mediates the extrusion of chemotherapeutic drugs from cancer cells. Characterization of the drug binding and ATPase activities of the protein have made it the paradigm ATP binding cassette (ABC) transporter. P-glycoprotein has been imaged at low resolution by electron cryo-microscopy and extensively analyzed by disulphide cross-linking, but a high resolution structure solved ab initio remains elusive. Homology models of P-glycoprotein were generated usi...

Stenham, Dr; Campbell, Jd; Sansom, Ms; Higgins, CF; Kerr, Id; Linton, Kj

2003-01-01

108

Interaction of CCN1 with ?v?3 integrin induces P-glycoprotein and confers vinblastine resistance in renal cell carcinoma cells.  

Science.gov (United States)

Renal cell carcinoma (RCC) ranks among the most chemoresistant tumors, and P-glycoprotein (P-gp) predominates multidrug resistance mechanisms by reducing the accumulation of intracellular chemotherapy drugs such as vinblastine (VBL), which is considered the most effective chemotherapeutic agent for this neoplasia. Unfortunately, the mechanism by which the expression of P-gp is regulated and the ways to inhibit the function of P-gp are poorly understood. Our study was carried out to determine the possible role of CCN1 in P-pg-mediated drug resistance on the basis of the validated function of CCN1, an extracellular matrix protein, in promoting chemoresistance. As expected, CCN1 was overexpressed in VBL-resistant cell lines (ACHN/VBL, A498/VBL, Caki-1/VBL, and Caki-2/VBL) as measured by enzyme-linked immunosorbent assay. We then transfected non-VBL-resistant cell lines with Ad-CCN1 and observed that the IC50 of VBL increased by about 3-5 times. Furthermore, both CCN1 antibody neutralization and ?v?3 integrin antibody blockade decreased the IC50 of VBL, which showed that CCN1 and ?v?3 are associated with resistance to VBL in RCC. Simultaneously, the enhanced expression of CCN1 triggered the intracellular PI3K/Akt pathway by binding ?v?3 integrin, as shown by western blot. P-gp expression was augmented in response to activation of the PI3K/Akt pathway, which could be modified by PI3K inhibitor LY294002 or multidrug resistance siRNA transfection. Therefore, targeted restraint of CCN1 or ?v?3 integrin in combination with the administration of VBL may be beneficial in the treatment of primary and metastatic RCC. PMID:23744557

Long, Qing-Zhi; Zhou, Ming; Liu, Xiao-Gang; Du, Yue-Feng; Fan, Jin-Hai; Li, Xiang; He, Da-Lin

2013-09-01

109

P-glycoprotein and breast cancer resistance protein expression in human placentae of various gestational ages.  

Science.gov (United States)

Placental efflux transporters such as P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) protect the developing fetus from exposure to potentially toxic xenobiotics. However, little is known about the expression of these transporters in human placentae of different gestational ages. Therefore, we quantified the expression of P-gp and BCRP in human placentae of different gestational ages. We also measured the expression of various nuclear regulatory factors such as the pregnane xenobiotic factor to determine whether their expression also changes with gestational age. Syncitial microvillous plasma membranes were isolated from human placentae of various gestational ages (60-90 days, 90-120 days, and full-term C-section placentae). P-gp and BCRP expression (protein) in these preparations were measured by Western blot analysis followed by an ELISA. Expression (mRNA) of P-gp, BCRP, and nuclear regulatory factors in the placentae were quantified by quantitative real-time PCR. P-gp expression (relative to that of alkaline phosphatase) was significantly (P < 0.05) higher (44.8-fold as protein; 6.5-fold as mRNA) in early gestational age human placentae (60-90 days) vs. term placentae. In contrast, BCRP (protein and mRNA) and nuclear regulatory factors (mRNA) expression in placental tissue did not change significantly with gestational age. However, placental expression of P-gp and human chorionic gonadotropin-beta (hCG-beta) transcripts was highly correlated (r = 0.73; P < 0.0001; Spearman rank correlation). Expression of P-gp, but not BCRP, decreases dramatically with gestational age in human placentae. This decrease in P-gp expression is not caused by a change in expression of nuclear receptor transcripts but appears to be related to hCG-beta expression. The placental P-gp expression appears to be upregulated in early pregnancy to protect the fetus from xenobiotic toxicity at a time when it is most vulnerable to such toxicity. PMID:15961534

Mathias, Anita A; Hitti, Jane; Unadkat, Jashvant D

2005-10-01

110

Nocardioazines: a novel bridged diketopiperazine scaffold from a marine-derived bacterium inhibits P-glycoprotein.  

Science.gov (United States)

An Australian marine sediment-derived isolate, Nocardiopsis sp. (CMB-M0232), yielded a new class of prenylated diketopiperazine, indicative of the action of a uniquely regioselective diketopiperazine indole prenyltransferase. The bridged scaffold of nocardioazine A proved to be a noncytotoxic inhibitor of the membrane protein efflux pump P-glycoprotein, reversing doxorubicin resistance in a multidrug resistant colon cancer cell. PMID:21513295

Raju, Ritesh; Piggott, Andrew M; Huang, Xiao-Cong; Capon, Robert J

2011-05-20

111

Effects of Rifampin and Multidrug Resistance Gene Polymorphism on Concentrations of Moxifloxacin?  

OpenAIRE

Treatment regimens combining moxifloxacin and rifampin for drug-susceptible tuberculosis are being studied intensively. However, rifampin induces enzymes that transport and metabolize moxifloxacin. We evaluated the effect of rifampin and the human multidrug resistance gene (MDR1) C3435T polymorphisms (P-glycoprotein) on moxifloxacin pharmacokinetic parameters. This was a single-center, sequential design study with 16 volunteers in which sampling was performed after four daily oral doses of mo...

Weiner, Marc; Burman, William; Luo, Chi-cheng; Peloquin, Charles A.; Engle, Melissa; Goldberg, Stefan; Agarwal, Vipin; Vernon, Andrew

2007-01-01

112

Enhanced Brain Disposition and Effects of ?9-Tetrahydrocannabinol in P-Glycoprotein and Breast Cancer Resistance Protein Knockout Mice  

OpenAIRE

The ABC transporters P-glycoprotein (P-gp, Abcb1) and breast cancer resistance protein (Bcrp, Abcg2) regulate the CNS disposition of many drugs. The main psychoactive constituent of cannabis ?9-tetrahydrocannabinol (THC) has affinity for P-gp and Bcrp, however it is unknown whether these transporters modulate the brain accumulation of THC and its functional effects on the CNS. Here we aim to show that mice devoid of Abcb1 and Abcg2 retain higher brain THC levels and are more sensitive to can...

Spiro, Adena S.; Wong, Alexander; Boucher, Aure?lie A.; Arnold, Jonathon C.

2012-01-01

113

A Novel ATP-Binding Cassette Transporter Involved in Multidrug Resistance in the Phytopathogenic Fungus Penicillium digitatum  

OpenAIRE

Demethylation inhibitor (DMI)-resistant strains of the plant pathogenic fungus Penicillium digitatum were shown to be simultaneously resistant to cycloheximide, 4-nitroquinoline-N-oxide (4NQO), and acriflavine. A PMR1 (Penicillium multidrug resistance) gene encoding an ATP-binding cassette (ABC) transporter (P-glycoprotein) was cloned from a genomic DNA library of a DMI-resistant strain (LC2) of Penicillium digitatum by heterologous hybridization with a DNA fragment containing an ABC-encoding...

Nakaune, Ryoji; Adachi, Kiichi; Nawata, Osamu; Tomiyama, Masamitsu; Akutsu, Katsumi; Hibi, Tadaaki

1998-01-01

114

Current Status on Marine Products with Reversal Effect on Cancer Multidrug Resistance  

Directory of Open Access Journals (Sweden)

Full Text Available The resistance of tumor cells to a broad range of anticancer agents continues to be a problem for the success of cancer chemotherapy. Multidrug resistance (MDR is due in part to three drug transporter proteins: ABCB1/P-glycoprotein (P-gp, ABCC1/multidrug resistance protein 1 (MRP1 and ABCG2/breast cancer resistance protein (BCRP. These transporters are part of the ATP-binding cassette (ABC superfamily, whose members function as ATP-dependent drug-efflux pumps. Their activity can be blocked by various drugs such as verapamil (calcium channel blocker and cyclosporin A (immunosuppressive agent, etc. These compounds are called MDR modulators or reversals. This review highlights several marine natural products with reversal effect on multidrug resistance in cancer, including agosterol A, ecteinascidin 743, sipholane triterpenoids, bryostatin 1, and welwitindolinones.

Huiqin Guo

2012-10-01

115

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

Science.gov (United States)

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. PMID:25459885

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

2015-01-01

116

Development and characterization of P-glycoprotein 1 (Pgp1, ABCB1)-mediated doxorubicin-resistant PLHC-1 hepatoma fish cell line  

International Nuclear Information System (INIS)

The development of the multidrug resistance (MDR) phenotype in mammals is often mediated by the overexpression of the P-glycoprotein1 (Pgp, ABCB1) or multidrug resistance-associated protein (MRP)-like ABC transport proteins. A similar phenomenon has also been observed and considered as an important part of the multixenobiotic resistance (MXR) defence system in aquatic organisms. We have recently demonstrated the presence of ABC transporters in the widely used in vitro fish model, the PLHC-1 hepatoma cell line. In the present study we were able to select a highly resistant PLHC-1 sub-clone (PLHC-1/dox) by culturing the wild-type cells in the presence of 1 ?M doxorubicin. Using quantitative PCR a 42-fold higher expression of ABCB1 gene was determined in the PLHC-1/dox cells compared to non-selected wild-type cells (PLHC-1/wt). The efflux rates of model fluorescent Pgp1 substrates rhodamine 123 and calcein-AM were 3- to 4-fold higher in the PLHC-1/dox in comparison to the PLHC-1/wt cells. PLHC-1/dox were 45-fold more resistant to doxorubicin cytotoxicity than PLHC-1/wt. Similarly to mammalian cell lines, typical cross-resistance to cytotoxicity of other chemotherapeutics such as daunorubicin, vincristine, vinblastine, etoposide and colchicine, occurred. Furthermore, cyclosporine A, verapamil and PSC833, specific inhibitors of Pgp1 transport activity, completely reversed resistance of PLHC-1/dox cells to all tested drugs, resulting in EC50 values similar to the EC50 valug in EC50 values similar to the EC50 values found for PLHC-1/wt. In contrast, MK571, a specific inhibitor of MRP type of efflux transporters, sensitized PLHC-1/dox cells, neither to doxorubicin, nor to any other of the chemotherapeutics used in the study. These data demonstrate for the first time that a specific Pgp1-mediated doxorubicin resistance mechanism is present in the PLHC-1 fish hepatoma cell line. In addition, the fact that low micromolar concentrations of specific inhibitors may completely reverse a highly expressed doxorubicin resistance points to the fragility of Pgp1-mediated MXR defence mechanism in fish

117

Visualization of multidrug resistance in vivo  

International Nuclear Information System (INIS)

Various mechanisms are involved in multidrug resistance (MDR) for chemotherapeutic drugs, such as the drug efflux pumps, P-glycoprotein (Pgp) and multidrug resistance-associated protein (MRP). In this review the mechanisms involved in MDR are described and results are reviewed with particular attention to the in vivo imaging of Pgp and MRP. Various detection assays provide information about the presence of drug efflux pumps at the mRNA and protein levels. However, these methods do not yield information about the dynamic function of Pgp and MRP in vivo. For the study of Pgp- and MRP-mediated transport, single-photon emission tomography (SPET) and positron emission tomography (PET) are available. Technetium-99m sestamibi is a substrate for Pgp and MRP, and has been used in clinical studies for tumour imaging, and to visualize blockade of Pgp-mediated transport after modulation of the Pgp pump. Other 99mTc radiopharmaceuticals, such as 99mTc-tetrofosmin and several 99Tc-Q complexes, are also substrates for Pgp, but to date only results from in vitro and animal studies are available for these compounds. Several agents, including [11C]colchicine, [11C]verapamil and [11C]daunorubicin, have been evaluated for the quantification of Pgp-mediated transport with PET in vivo. The results suggest that radiolabelled colchicine, verapamil and daunorubicin are feasible substrates with which to image Pgp function in tumes with which to image Pgp function in tumours. Uptake of [11C]colchicine and [11C]verapamil is relatively high in the chest area, reducing the value of both tracers for monitoring Pgp-mediated drug transport in tumours located in this region. In addition, it has to be borne in mind that only comparison of Pgp-mediated transport of radioalabelled substrates in the absence and in the presence of Pgp blockade gives quantitative information on Pgp-mediated pharmacokinetics. Leukotrienes are specific substrates for MRP. Therefore, N-[11C]acetyl-leukotriene E4 provides an opportunity to study MRP function non-invasively. Results obtained in MRP2 mutated GY/TR rats have demonstrated visualization of MRP-mediated transport. This tracer permits the study of MRP transport function abnormalities in vivo, e.g. in Dubin-Johnson patients, who are MRP2 gene deficient. Results obtained show the feasibility of using SPET and PET to study the functionality of MDR transporters in vivo. (orig.)

118

Visualization of multidrug resistance in vivo  

Energy Technology Data Exchange (ETDEWEB)

Various mechanisms are involved in multidrug resistance (MDR) for chemotherapeutic drugs, such as the drug efflux pumps, P-glycoprotein (Pgp) and multidrug resistance-associated protein (MRP). In this review the mechanisms involved in MDR are described and results are reviewed with particular attention to the in vivo imaging of Pgp and MRP. Various detection assays provide information about the presence of drug efflux pumps at the mRNA and protein levels. However, these methods do not yield information about the dynamic function of Pgp and MRP in vivo. For the study of Pgp- and MRP-mediated transport, single-photon emission tomography (SPET) and positron emission tomography (PET) are available. Technetium-99m sestamibi is a substrate for Pgp and MRP, and has been used in clinical studies for tumour imaging, and to visualize blockade of Pgp-mediated transport after modulation of the Pgp pump. Other {sup 99m}Tc radiopharmaceuticals, such as {sup 99m}Tc-tetrofosmin and several {sup 99}Tc-Q complexes, are also substrates for Pgp, but to date only results from in vitro and animal studies are available for these compounds. Several agents, including [{sup 11}C]colchicine, [{sup 11}C]verapamil and [{sup 11}C]daunorubicin, have been evaluated for the quantification of Pgp-mediated transport with PET in vivo. The results suggest that radiolabelled colchicine, verapamil and daunorubicin are feasible substrates with which to image Pgp function in tumours. Uptake of [{sup 11}C]colchicine and [{sup 11}C]verapamil is relatively high in the chest area, reducing the value of both tracers for monitoring Pgp-mediated drug transport in tumours located in this region. In addition, it has to be borne in mind that only comparison of Pgp-mediated transport of radioalabelled substrates in the absence and in the presence of Pgp blockade gives quantitative information on Pgp-mediated pharmacokinetics. Leukotrienes are specific substrates for MRP. Therefore, N-[{sup 11}C]acetyl-leukotriene E{sub 4} provides an opportunity to study MRP function non-invasively. Results obtained in MRP{sub 2} mutated GY/TR rats have demonstrated visualization of MRP-mediated transport. This tracer permits the study of MRP transport function abnormalities in vivo, e.g. in Dubin-Johnson patients, who are MRP{sub 2} gene deficient. Results obtained show the feasibility of using SPET and PET to study the functionality of MDR transporters in vivo. (orig.) With 3 figs., 91 refs.

Hendrikse, N.H. [PET Center, University Hospital, Groningen (Netherlands)]|[Department of Internal Medicine, Division of Medical Oncology, University Hospital, Groningen (Netherlands); Franssen, E.J.F. [PET Center, University Hospital, Groningen (Netherlands)]|[Department of Nuclear Medicine, University Hospital, Groningen (Netherlands); Graaf, W.T.A. van der; Vries, E.G.E. de [Department of Internal Medicine, Division of Medical Oncology, University Hospital, Groningen (Netherlands); Vaalburg, W. [PET Center, University Hospital, Groningen (Netherlands)

1999-03-01

119

Localization of P-glycoprotein at the nuclear envelope of rat brain cells  

International Nuclear Information System (INIS)

P-Glycoprotein is a plasma membrane drug efflux protein implicated in extrusion of cytotoxic compounds out of a cell. There is now evidence that suggests expression of this transporter at several subcellular sites, including the nucleus, mitochondria, and Golgi apparatus. This study investigated the localization and expression of P-glycoprotein at the nuclear membrane of rat brain microvessel endothelial (RBE4) and microglial (MLS-9) cell lines. Immunocytochemistry at the light and electron microscope levels using P-glycoprotein monoclonals antibodies demonstrated the localization of the protein at the nuclear envelope of RBE4 and MLS-9 cells. Western blot analysis revealed a single band of 170-kDa in purified nuclear membranes prepared from isolated nuclei of RBE4 and MLS-9 cells. These findings indicate that P-glycoprotein is expressed at the nuclear envelope of rat brain cells and suggest a role in multidrug resistance at this subcellular site

120

Localization of P-glycoprotein at the nuclear envelope of rat brain cells.  

Science.gov (United States)

P-glycoprotein is a plasma membrane drug efflux protein implicated in extrusion of cytotoxic compounds out of a cell. There is now evidence that suggests expression of this transporter at several subcellular sites, including the nucleus, mitochondria, and Golgi apparatus. This study investigated the localization and expression of P-glycoprotein at the nuclear membrane of rat brain microvessel endothelial (RBE4) and microglial (MLS-9) cell lines. Immunocytochemistry at the light and electron microscope levels using P-glycoprotein monoclonals antibodies demonstrated the localization of the protein at the nuclear envelope of RBE4 and MLS-9 cells. Western blot analysis revealed a single band of 170-kDa in purified nuclear membranes prepared from isolated nuclei of RBE4 and MLS-9 cells. These findings indicate that P-glycoprotein is expressed at the nuclear envelope of rat brain cells and suggest a role in multidrug resistance at this subcellular site. PMID:17651695

Babakhanian, Karlo; Bendayan, Moise; Bendayan, Reina

2007-09-21

121

Reversal of multidrug resistance in HL-60 cells by verapamil and liposome-encapsulated doxorubicin.  

Science.gov (United States)

The means of circumventing multidrug resistance was investigated in HL-60 and HL-60R (a drug resistance variant) cell lines. The HL-60R cell line was developed from the parent line by serial exposure to increasing concentrations of doxorubicin over a 4-month period. This drug resistant cell line expressed P-glycoprotein in its cell surface and is 80-fold more resistant than the parent cell line. Multidrug resistance, as evaluated by a cell cytotoxicity assay using doxorubicin, can be overcome by use of verapamil. Multidrug resistance can also be circumvented when doxorubicin is encapsulated in liposomes. The combination of verapamil and doxorubicin-encapsulated liposomes does enhance circumvention of multidrug resistance beyond the effect of each agent alone, implying a synergistic effect. The lipid composition of the liposomes does affect the rate of drug uptake but not the overall cytotoxic effect of doxorubicin. The synergistic reversal of multidrug resistance by doxorubicin-encapsulated liposomes and verapamil suggests a multifactorial basis for drug resistance in this cell line. PMID:1673873

Sadasivan, R; Morgan, R; Fabian, C; Stephens, R

1991-05-01

122

Detection of expression and modulation of multidrug-resistance (MDR) and establishment of a new bioassay  

International Nuclear Information System (INIS)

The present thesis deals with the resistance of human malignant cells against cellular toxicity of anticancer drugs, a phenomenon representing one of the major obstacles to successful chemotherapy. One mechanism underlying a cross-resistance to different drugs called multidrug resistance (MDR) is characterized by the expression of an active transport protein (P-glycoprotein), causing decreased intracellular drug retention and cytotoxicity. The main subjects of the present work were to establish different detection methods for MDR and its modulation (by substances blocking activity of P-glycoprotein) including immunological methods (immunocytochemistry, radioimmunoassay), molecular biology (slot-blot analysis, in-situ hybridization) and functional assays (drug-accumulation analysis, drug-cytotoxicity analysis). The methods were evaluated and compared using human and mouse MDR control cell lines and human tumor cell lines established in our laboratory. In cell lines derived from human melanoma - a malignancy insensitive to chemotherapy - expression of P-glycoprotein of relatively low transporting activity was detected by different methods in 8 of 33 cases. Furthermore a new sensitive in vitro assay for the functional detection of MDR was established using the biological features of cytochalasins, a microfilament disrupting substance group. These compounds were shown to be substrates for the P-glycoprotein efflux pump and their effects on cell division (blockade of cytokffects on cell division (blockade of cytokinesis resulting in multinucleate cells) correlated with MDR-activity of the tested cells. With this new assay P-glycoprotein activity can be demonstrated and analysed over a wide range of resistance against different cytotoxic drugs. Therefore it may by a suitable tool for research and diagnosis in the field of drug resistance

123

Effect of curcumin on human colon cancer multidrug resistance in vitro and in vivo  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english OBJECTIVE: To determine whether curcumin reverses the multidrug resistance of human colon cancer cells in vitro and in vivo. METHODS: In a vincristine-resistant cell line of human colon cancer, the cell viability of curcumin-treated cells was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5- [...] diphenyltetrazolium bromide assay. Rhodamine123 efflux was evaluated to detect P-glycoprotein transporter activity, and expression of the multidrug resistance protein 1 and survivin genes was analyzed by reverse transcription polymerase chain reaction and western blotting. In addition, xenograft mouse tumors were grown and treated with curcumin. The morphology of the xenografts was investigated by hematoxylin-eosin staining. The in vivo expression of the multidrug resistance gene and P-glycoprotein and survivin genes and proteins was observed using reverse transcription-polymerase chain reaction and western blotting, respectively. RESULTS: Curcumin was not obviously toxic to the vincristine-resistant human colon cancer cells at concentrations less than 25 ?M, but the growth of cells was significantly inhibited. At concentrations greater than 25 ?M, curcumin was toxic in a concentration-dependent manner. The sensitivity of cells to vincristine, cisplatin, fluorouracil, and hydroxycamptothecin was enhanced, intracellular Rhodamine123 accumulation was increased (p

Wei-Dong, Lu; Yong, Qin; Chuang, Yang; Lei, Li.

2013-05-01

124

Multifactorial resistance to adriamycin: relationship of DNA repair, glutathione transferase activity, drug efflux, and P-glycoprotein in cloned cell lines of adriamycin-sensitive and -resistant P388 leukemia.  

Science.gov (United States)

Cloned lines of Adriamycin (ADR)-sensitive and -resistant P388 leukemia have been established, including P388/ADR/3 and P388/ADR/7 that are 5- and 10-fold more resistant than the cloned sensitive cell line P388/4 (Cancer Res., 46: 2978, 1986). A time course of ADR-induced DNA double-strand breaks revealed that in sensitive P388/4 cells, evidence of DNA repair was noted 4 h after removal of drug, whereas in resistant clone 3 and 7 cells repair was observed 1 h after drug removal. The earlier onset of DNA repair was statistically significant (p = 0.0154 for clone 3 cells, and p = 0.0009 for clone 7 cells). By contrast, once the repair process was initiated, the rate of repair was similar for all three cell lines. The level of glutathione transferase activity was determined in whole cell extracts. Enzyme activity (mean +/- SE) in sensitive cells was 9.49 +/- 1.00 nmol/min/mg protein, that in resistant clone 3 cells was 13.36 +/- 1.03 nmol/min/mg, and that in clone 7 cells was 13.96 +/- 1.44 nmol/min/mg; the 1.44-fold increase in enzyme activity in resistant cells was statistically significant (p = 0.01). Further evidence of induction of glutathione transferase was provided by Northern blot analysis using a 32P-labeled cDNA for an anionic glutathione transferase, which demonstrated approximately a twofold increase in mRNA in resistant clone 7 cells. Western blot analysis with a polyvalent antibody against anionic glutathione transferase also revealed a proportionate increase in gene product in resistant cells. Dose-survival studies showed that ADR-resistant cells were cross-resistant to actinomycin D, daunorubicin, mitoxantrone, colchicine, and etoposide, but not to the alkylating agent melphalan; this finding provided evidence that these cells are multidrug resistant. Using a cDNA probe for P-glycoprotein, a phenotypic marker for multidrug resistance, Northern blot analysis showed an increase in the steady state level of mRNA of approximately twofold in resistant clone 3 and 7 cells. Southern analysis with the same cDNA probe showed no evidence of gene amplification or rearrangement. Western blot analysis with monoclonal C219 antibody demonstrated a distinct increase in P-glycoprotein in resistant cells. Efflux of Adriamycin as measured by the efflux rate constant was identical in all three cell lines. Furthermore, the metabolic inhibitors azide and dinitrophenol did not augment drug uptake in either sensitive or resistant cells. These findings suggest that despite the increase in P-glycoprotein, an active extrusion pump was not operational in these cells.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2897875

Deffie, A M; Alam, T; Seneviratne, C; Beenken, S W; Batra, J K; Shea, T C; Henner, W D; Goldenberg, G J

1988-07-01

125

Functional imaging of the multidrug resistance in vivo  

Energy Technology Data Exchange (ETDEWEB)

Although diverse mechanisms are involved in multidrug resistance for chemotherapeutic drugs, the development of cellular P-glycoprotein(Pgp) and multidrug-resistance associated protein (MRP) are improtant factors in the chemotherapy failure to cancer. Various detection assays provide information about the presence of drug efflux pumps at the mRNA and protein levels. However these methods do not yield information about dynamic function of Pgp and MRP in vivo. Single photon emission tomograpy (SPECT) and positron emission tomograpy (PET) are available for the detection of Pgp and MRP-mediated transport. {sup 99m}Tc-sestaMIBI and other {sup 99m}Tc-radiopharmaceuticals are substrates for Pgp and MRP, and have been used in clinical studies of 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. Results obtained from recent publications are reviewed to confirm the feasibility of using SPECT and PET to study the functionality of MDR transportes in vivo.

Lee, Jae Tae [College of Medicine, Kyungpook National Univ., Taegu (Korea, Republic of)

2001-07-01

126

Functional imaging of the multidrug resistance in vivo  

International Nuclear Information System (INIS)

Although diverse mechanisms are involved in multidrug resistance for chemotherapeutic drugs, the development of cellular P-glycoprotein(Pgp) and multidrug-resistance associated protein (MRP) are improtant factors in the chemotherapy failure to cancer. Various detection assays provide information about the presence of drug efflux pumps at the mRNA and protein levels. However these methods do not yield information about dynamic function of Pgp and MRP in vivo. Single photon emission tomograpy (SPECT) and positron emission tomograpy (PET) are available for the detection of Pgp and MRP-mediated transport. 99mTc-sestaMIBI and other 99mTc-radiopharmaceuticals are substrates for Pgp and MRP, and have been used in clinical studies of tumor imaging, and to visualize blockade of Pgp-mediated transport after modulation of Pgp pump. Colchicine, verapamil and daunorubicin labeled with 11C 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-(11C]acetyl-leukotriene E4 provides an opportunity to study MRP function non-invasively in vivo. Results obtained from recent publications are reviewed to confirm the feasibility of using SPECT and PET to study the functionality of MDR transportes in vivo

127

Inhibition of anticancer drug efflux transporter P-glycoprotein by rosemary phytochemicals.  

Science.gov (United States)

The effects of dietary antioxidative and chemopreventive rosemary phytochemicals on the function of the human drug efflux transporter P-glycoprotein (MDR1, ABCB1) and multidrug resistance protein 1 (MRP1, ABCC1) were investigated using P-glycoprotein-overexpressing human carcinoma KB-C2 cells and human MRP1 gene-transfected KB/MRP cells. The effects of natural phytochemicals found in rosemary such as carnosic acid, carnosol, rosmarinic acid, and ursolic acid were investigated. The accumulation of daunorubicin or rhodamine 123, fluorescent substrates of P-glycoprotein, in KB-C2 cells increased in the presence of carnosic acid, carnosol, and ursolic acid in a concentration-dependent manner. In contrast, carnosic acid, carnosol, rosmarinic acid, and ursolic acid had no effects on the accumulation of calcein, a fluorescent substrate of MRP1, in KB/MRP cells. The ATPase activities of P-glycoprotein were stimulated by carnosic acid, carnosol, and ursolic acid. KB-C2 cells were sensitized to vinblastine cytotoxicity by carnosic acid, showing that carnosic acid reverses multidrug resistance. These results suggest that rosemary phytochemicals, such as carnosic acid, have inhibitory effects on anticancer drug efflux transporter P-glycoprotein and may become useful to enhance the efficacy of cancer chemotherapy. PMID:19944162

Nabekura, Tomohiro; Yamaki, Takeshi; Hiroi, Takashi; Ueno, Kazuyuki; Kitagawa, Shuji

2010-03-01

128

Nanodrug delivery in reversing multidrug resistance in cancer cells  

Science.gov (United States)

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 MDR in cancer cell. PMID:25071577

Kapse-Mistry, Sonali; Govender, Thirumala; Srivastava, Rohit; Yergeri, Mayur

2014-01-01

129

Nanodrug Delivery in Reversing Multidrug Resistance in Cancer Cells  

Directory of Open Access Journals (Sweden)

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 MDR in cancer cell

MayurYergeri

2014-07-01

130

P-glycoprotein and breast cancer resistance protein in acute myeloid leukaemia cells treated with the Aurora-B Kinase Inhibitor barasertib-hQPA  

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Full Text Available Abstract Background Aurora kinases play an essential role in orchestrating chromosome alignment, segregation and cytokinesis during mitotic progression, with both aurora-A and B frequently over-expressed in a variety of human malignancies. Over-expression of the ABC drug transporter proteins P-glycoprotein (Pgp and Breast cancer resistance protein (BCRP is a major obstacle for chemotherapy in many tumour types with Pgp conferring particularly poor prognosis in acute myeloid leukaemia (AML. Barasertib-hQPA is a highly selective inhibitor of aurora-B kinase that has shown tumouricidal activity against a range tumour cell lines including those of leukaemic AML origin. Methods Effect of barasertib-hQPA on the pHH3 biomarker and cell viability was measured in a panel of leukaemic cell lines and 37 primary AML samples by flow cytometry. Pgp status was determined by flow cytometry and BCRP status by flow cytometry and real-time PCR. Results In this study we report the creation of the cell line OCI-AML3DNR, which over-expresses Pgp but not BCRP or multidrug resistance-associated protein (MRP, through prolonged treatment of OCI-AML3 cells with daunorubicin. We demonstrate that Pgp (OCI-AML3DNR and KG-1a and BCRP (OCI-AML6.2 expressing AML cell lines are less sensitive to barasertib-hQPA induced pHH3 inhibition and subsequent loss of viability compared to transporter negative cell lines. We also show that barasertib-hQPA resistance in these cell lines can be reversed using known Pgp and BCRP inhibitors. We report that barasertib-hQPA is not an inhibitor of Pgp or BCRP, but by using 14[C]-barasertib-hQPA that it is effluxed by these transporters. Using phosphoHistone H3 (pHH3 as a biomarker of barasertib-hQPA responsiveness in primary AML blasts we determined that Pgp and BCRP positive primary samples were less sensitive to barasertib-hQPA induced pHH3 inhibition (p = 50 inhibition of pHH3 by barasertib-hQPA was achieved in 94.6% of these samples after 1 hour drug treatment, in contrast to the resistance of the cell lines. Conclusion We conclude that Pgp and BCRP status and pHH3 down-regulation in patients treated with barasertib should be monitored in order to establish whether transporter-mediated efflux is sufficient to adversely impact on the efficacy of the agent.

Russell Nigel H

2011-06-01

131

Reversal of P-Glycoprotein-Mediated Multidrug Resistance by Terpenoids from Maytenus Species  

OpenAIRE

The phytochemical analysis of the root bark extracts of the Chilean Maytenus, M. chubutensis, and M. magellanica (Celastraceae), led to the isolation of one phenolic nortriterpene, 1, and one diterpene with a nor-ent-kaurene skeleton, 2. In addition, four known compounds were isolated, among which compound 3 has been isolated for the first time from a natural source. Their structures were elucidated by spectroscopic methods, including 1D- and 2D-NMR (COSY, ROESY, HSQC, and HMBC) experiments, ...

Kennedy, M. L.; Llanos, G. G.; Castanys, S.; Gamarro, F.; Bazzocchi, I. L.; Jime?nez, I. A.

2011-01-01

132

P-glycoprotein and Topoisomerase II ? Expression in Advanced Gastric Cancer Patients: Association with Clinicopathological Findings  

OpenAIRE

Comparative study of markers of drug resistance in cancer tissues may be extremely helpful in selection of effective chemotherapeutic regimen. P-glycoprotein (P-gp) and Topoisomerase II ? (Topo II ?) are two fundamental proteins in multi-drug resistance phenomenon (MDR). This study determined the expression and significance of P-gp and Topo II ? proteins in advanced gastric carcinomas and correlated molecular alterations with clinicopathological findings. Tissue samples of 35 patients with...

Sepideh Arbabi Bidgoli; Bagher Minaee; Mansoor Djamali Zavarehi; Shamileh Fouladdel; Ebrahim Azizi

2006-01-01

133

Biochemical Mechanism of Modulation of Human P-glycoprotein by Stemofoline  

OpenAIRE

The resistance to chemotherapeutic drugs by cancer cells is considered to be one of the major obstacles for success in the treatment of cancer. A major mechanism underlying this multidrug resistance is the overexpression of P-glycoprotein (P-gp), resulting in an insufficient drug delivery to the tumor sites. A previous study has shown that stemofoline, an alkaloid isolated from Stemona burkillii could enhance the sensitivity of chemotherapeutics in a synergistic fashion. In the present study,...

Chanmahasathien, Wisinee; Ohnuma, Shinobu; Ambudkar, Suresh V.; Limtrakul, Pornngarm

2011-01-01

134

Multi-drug resistance 1 genetic polymorphism and prediction of chemotherapy response in Hodgkin's Lymphoma  

OpenAIRE

Abstract Background The human multi-drug resistance gene (MDR1), which encodes the major trans-membrane transporter P-glycoprotein (P-gp), was found to be associated with susceptibility to cancer and response to chemotherapy. The C3435T Polymorphism of MDR1 gene was correlated with expression levels and functions of P-gp. Here, we studied the association between MDR1 C3435T polymorphism and susceptibility to Hodgkin lymphoma (HL) and patient's response to ABVD chemotherapy regimen. Methods a ...

Haddadin William J; Matalka Ismail I; Alzoubi Karem H; Khabour Omar F; Alshogran Osama Y; Mhaidat Nizar M; Mahasneh Ibraheem O; Aldaher Ahmad N

2011-01-01

135

Partial synthesis and biological evaluation of bisbenzylisoquinoline alkaloids derivatives: potential modulators of multidrug resistance in cancer.  

Science.gov (United States)

A series of new bisbenzylisoquinoline alkaloids was partially synthesized from tetrandrine and fangchinoline and evaluated for their ability to reverse P-glycoprotein-mediated multidrug resistance (MDR) in cancer cells. All the test compounds increased the intracellular accumulation rate of rhodamine 123 in MDR cells (Bel7402 and HCT8), and most exhibited more potent MDR-reversing activity relative to the reference compound verapamil. Compounds 8, 10, 13, and 14 enhanced intracellular accumulation of doxorubicin in Bel7402 and HCT8 cells. PMID:22587798

He, Ping; Sun, Hua; Jian, Xi-Xian; Chen, Qiao-Hong; Chen, Dong-Lin; Liu, Geng-Tao; Wang, Feng-Peng

2012-01-01

136

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

DEFF Research Database (Denmark)

An Ehrlich ascites tumour cell line (EHR2) was selected for resistance to etoposide (VP16) by in vivo exposure to this agent. The resulting cell line (EHR2/VP16) was 114.3-, 5.7-, and 4.0-fold resistant to VP16, daunorubicin, and vincristine, respectively. The amount of salt-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 accumulation of [(3)H]VP16 and daunorubicin was reduced by 64% and 17%, respectively, as compared with EHR2. Deprivation of energy by addition of sodium azide increased the accumulation of both drugs to the level of sensitive cells. When glycolysis was restored by the addition of glucose to EHR2/VP16 cells loaded with drug in the presence of sodium azide, extrusion of [(3)H]VP16 and daunorubicin was induced. Addition of verapamil (25 microM) decreased the efflux of daunorubicin to the level of sensitive cells, but had only a moderate effect on the efflux of [(3)H]VP16. The resistant cells showed moderate sensitisation to VP16 on treatment with verapamil, whereas cyclosporin A had no effect. Compared with that of sensitive cells, the ATPase activity of plasma membrane vesicles prepared from EHR2/VP16 cells was very low. Vanadate inhibited the ATPase activity of EHR2/VP16 microsomes with a K(i) value of 30 microM. ATPase activity was slightly stimulated by daunorubicin, whereas vinblastine, verapamil, and cyclosporin A had no effect. In conclusion, development of resistance to VP16 in EHR2 is accompanied by a significant reduction in topoisomerase II (alpha and beta) and by increased expression of MRP mRNA (20-fold). MRP displays several points of resemblance to P-glycoprotein in its mode of action: 1) like P-glycoprotein, MRP causes resistance to a range of hydrophobic drugs; 2) MRP decreases drug accumulation in the cells and this decrease is abolished by omission of energy; and 3) MRP increases efflux of drug from cells. However, compared with that of P-glycoprotein-positive cells, the ATPase activity of MRP-positive cells is found to be low and not able to be stimulated by verapamil.

Nielsen, D; Maare, C

2000-01-01

137

[Perspectives of inhibition of multidrug resistance during cancer chemotherapy, in vitro and in vivo experiments].  

Science.gov (United States)

The development of pharmacological agents able to counteract the mechanisms of multidrug resistance in oncology has remained a major goal for the past ten years. Our purpose was to find multidrug resistance reversal agents less toxic than verapamil among various synthetic compounds: cinnamylidene ketones; 1,4-dihydropyridines; phenothiazines; heat shock 90 inhibitor peptides; betti base derivative of tylosin and among some naturally occurring plant derived jatrophane and lathyrane-type diterpenes. The first part of this thesis presents the inhibition of multidrug resistance through inhibition of the P-glycoprotein efflux pump in various cell lines. In general, the newly identified multidrug resistance modifiers were able to enhance the antiproliferative activity of selected anticancer drugs in a synergistic or additive way in in vitro experiments. The in vitro activity of betti base derivative of tylosin was confirmed by further in vivo efficacy studies in DBA/2 mice. As an alternative way of antitumor effect, apoptosis inductions of resistance modifiers were studied. The substituted dihydropyridine 13 was the most promising apoptosis inducer on mouse lymphoma cells. Human cytomegalovirus was used in a modified in vitro model for characterizing lathyrane compounds with antipromotion effect on human lung cancer cells. All the six macrocyclic lathyrane-type diterpenoids reduced the promotion in vitro , except latilagascene D, decreased IE-antigen expression of cytomegalovirus to prevent progression of tumor malignancy. PMID:19293063

Engi, Helga

2009-03-29

138

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

DEFF Research Database (Denmark)

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 (MDR1) gene single nucleotide polymorphisms (SNPs) G2677T and C3435T using the model drug digoxin.

Larsen, U L; Hyldahl Olesen, L

2007-01-01

139

Molecular models of human P-glycoprotein in two different catalytic states  

OpenAIRE

Abstract Background P-glycoprotein belongs to the family of ATP-binding cassette proteins which hydrolyze ATP to catalyse the translocation of their substrates through membranes. This protein extrudes a large range of components out of cells, especially therapeutic agents causing a phenomenon known as multidrug resistance. Because of its clinical interest, its activity and transport function have been largely characterized by various biochemical studies. In the absence of a high-resolution st...

Tulkens Paul M; Van Bambeke Françoise; Depret Grégoire; Becker Jean-Paul; Prévost Martine

2009-01-01

140

The Phosphodiesterase-5 Inhibitor Vardenafil Is a Potent Inhibitor of ABCB1/P-Glycoprotein Transporter  

OpenAIRE

One of the major causes of chemotherapy failure in cancer treatment is multidrug resistance (MDR) which is mediated by the ABCB1/P-glycoprotein. Previously, through the use of an extensive screening process, we found that vardenafil, a phosphodiesterase 5 (PDE-5) inhibitor significantly reverses MDR in ABCB1 overexpressing cancer cells, and its efficacy was greater than that of tadalafil, another PDE-5 inhibitor. The present study was designed to determine the reversal mechanisms of vardenafi...

Ding, Pei-rong; Tiwari, Amit K.; Ohnuma, Shinobu; Lee, Jeferson W. K. K.; An, Xin; Dai, Chun-ling; Lu, Qi-si; Singh, Satyakam; Yang, Dong-hua; Talele, Tanaji T.; Ambudkar, Suresh V.; Chen, Zhe-sheng

2011-01-01

141

Detection of multidrug resistance using molecular nuclear technique  

International Nuclear Information System (INIS)

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. 99m-Tc-MIBI and other 99m-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 11C 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-(11C)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. Weso 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

142

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

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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.

Choi Cheol-Hee

2005-10-01

143

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

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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 mechanism of the HA117 gene may not be similar to that of MDR1.

Chen Tingfu

2010-07-01

144

A novel PET imaging protocol identifies seizure-induced regional overactivity of P-glycoprotein at the blood-brain barrier  

Science.gov (United States)

About one third of epilepsy patients are pharmacoresistant. Overexpression of P-glycoprotein and other multidrug transporters at the blood-brain barrier is thought to play an important role in drug-refractory epilepsy. Thus, quantification of regionally different P-glycoprotein activity in the brain in vivo is essential to identify P-glycoprotein overactivity as the relevant mechanism for drug-resistance in an individual patient. Using the radiolabeled P-glycoprotein substrate (R)-[11C]verapamil and different doses of co-administered tariquidar, which is an inhibitor of P-glycoprotein, we evaluated whether small-animal positron emission tomography (PET) can quantify regional changes in transporter function in the rat brain at baseline and 48 h after a pilocarpine-induced status epilepticus. P-glycoprotein expression was additionally quantified by immunohistochemistry. To reveal putative seizure-induced changes in blood-brain barrier integrity, we performed gadolinium-enhanced magnetic resonance scans on a 7.0 Tesla small-animal scanner. Before P-glycoprotein modulation, brain uptake of (R)-[11C]verapamil was low in all regions investigated in control and post-status epilepticus rats. After administration of 3 mg/kg tariquidar, which inhibits P-glycoprotein only partially, we observed increased regional differentiation in brain activity uptake in post-status epilepticus versus control rats, which diminished after maximal P-glycoprotein inhibition. Regional increases in the efflux rate constant k2, but not in distribution volume VT or influx rate constant K1, correlated significantly with increases in P-glycoprotein expression measured by immunohistochemistry. This imaging protocol proves to be suitable to detect seizure-induced regional changes in P-glycoprotein activity and is readily applicable to humans, with the aim to detect relevant mechanisms of pharmacoresistance in epilepsy in vivo. PMID:21677164

Bankstahl, Jens P.; Bankstahl, Marion; Kuntner, Claudia; Stanek, Johann; Wanek, Thomas; Meier, Martin; Ding, Xiao-Qi; Müller, Markus; Langer, Oliver; Löscher, Wolfgang

2013-01-01

145

Multidrug-resistant Tuberculosis in Military Recruits  

OpenAIRE

We conducted a tuberculosis contact investigation for a female military recruit with an unreported history of multidrug-resistant tuberculosis (MDRTB) and subsequent recurrence. Pertinent issues included identification of likely contacts from separate training phases, uncertainty on latent MDRTB infection treatment regimens and side effects, and subsequent dispersal of the contacts after exposure.

Freier, Grace; Wright, Allen; Nelson, Gregory; Brenner, Eric; Mase, Sundari; Tasker, Sybil; Matthews, Karen L.; Bohnker, Bruce K.

2006-01-01

146

Novel structure-activity relationships and selectivity profiling of cage dimeric 1,4-dihydropyridines as multidrug resistance (MDR) modulators.  

Science.gov (United States)

Synthesized series of cage dimeric 1,4-dihydropyridines have been systematically evaluated as MDR modulators in in vitro assays to investigate structure-dependent selectivity properties of inhibiting most cancer-relevant efflux pump proteins. Structure-activity relationships of each P-glycoprotein (P-gp) and multidrug resistance associated protein (MRP) 1 and MRP2 inhibition are discussed and prove to be mainly determined by certain aromatic substitution patterns. The characterization of breast cancer resistance protein (BCRP) inhibition results in the discovery of benzyloxy substituted derivatives as selective P-gp inhibitors. PMID:20598550

Coburger, Claudius; Wollmann, Jörg; Krug, Martin; Baumert, Christiane; Seifert, Marianne; Molnár, Joséf; Lage, Hermann; Hilgeroth, Andreas

2010-07-15

147

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)

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 ?-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.

Elizabeth E. Bygarski

2014-12-01

148

Influence of multidrug resistance on 18F-FCH cellular uptake in a glioblastoma model  

International Nuclear Information System (INIS)

Multidrug resistance, aggressiveness and accelerated choline metabolism are hallmarks of malignancy and have motivated the development of new PET tracers like 18F-FCH, an analogue of choline. Our aim was to study the relationship of multidrug resistance of cultured glioma cell lines and 18F-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 theng 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.)

149

Sepsis due to multidrug resistant Acinetobacter baumannii  

Directory of Open Access Journals (Sweden)

Full Text Available In this article we describe a multidrug resistant (MDR Acinetobacter baumannii nosocomial infection clinical case. This patient in spite of having received established medical treatment presented deterioration of his clinical condition. A deep research was made in several data bases in order to present updated information in the topic and to describe the mechanism of action of antibiotics and bacterial resistance that has made difficult the management of these patients.

Javier Enrique Hernández Blanco, Ana Milena Arrieta Aguilera, Dewitt Fabian Arcón Medina, Juan Enrique Castellano Orcasita

2012-12-01

150

Ixabepilone, a novel microtubule-targeting agent for breast cancer, is a substrate for P-glycoprotein (P-gp/MDR1/ABCB1) but not breast cancer resistance protein (BCRP/ABCG2).  

Science.gov (United States)

Ixabepilone is the first epothilone to be approved for clinical use. Current data suggest the epothilones have a role in treating taxane-resistant cancers and ixabepilone is unaffected by at least some of the mechanisms underlying chemoresistance. Here, we report a series of cytotoxicity and transport studies to assess the potential role of P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) in ixabepilone resistance. A significant decrease in ixabepilone-mediated cytotoxicity was observed in Madin-Darby canine kidney cells transfected with human multidrug resistance 1 (MDR1) comparative with the parental cells (IC(50) > 2000 nM versus 90 nM). Overexpression of P-gp also resulted in significantly decreased cell susceptibility to docetaxel, paclitaxel, and vinblastine. Bidirectional transport of ixabepilone across monolayers of porcine kidney-derived cells expressing human MDR1 showed a significantly increased efflux ratio relative to the parental cells. A BCRP-overexpressing cell line was developed by transfecting human embryonic kidney (HEK)-293 cells with BCRP cDNA and confirmed by immunoblotting and bodipy prazosin and mitoxantrone uptake. Neither P-gp nor multidrug resistance protein 2 was detected in the cells by corresponding polyclonal antibodies. This HEK-BCRP cell line demonstrated resistance to docetaxel, paclitaxel, vinblastine, and mitoxantrone, in comparison with the parental cell line (7.3, 4.3, 2.9, and 11.9 resistance factor, respectively). Transport inhibition by BCRP inhibitor fumitremorgin C and broad efflux inhibitor 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 (GF120918) restored drug sensitivity. In contrast, ixabepilone was far less susceptible to BCRP-mediated resistance, resulting in a resistance factor of only 1.2-fold. In summary, these results suggest that P-gp could cause resistance to ixabepilone in tumors and affect the disposition of the drug, but it is unlikely that BCRP mediates any drug resistance to ixabepilone. PMID:21262849

Shen, H; Lee, F Y; Gan, J

2011-05-01

151

Facing multi-drug resistant tuberculosis.  

Science.gov (United States)

Multi-drug resistant tuberculosis (MDR-TB) is caused by Mycobacterium tuberculosis strains resistant to at least two of the most effective anti-tuberculosis drugs (i.e., isoniazid and rifampicin). Therapeutic regimens based on second- and third-line anti-tuberculosis medicines showed poor efficacy, safety, and tolerability profiles. It was estimated that in 2012 the multi-drug resistant tuberculosis incidence ranged from 300,000 to 600,000 cases, mainly diagnosed in the Eastern European and Central Asian countries. The highest proportion of cases is among individuals previously exposed to anti-tuberculosis drugs. Three main conditions can favour the emergence and spread of multi-drug resistant tuberculosis: the poor implementation of the DOTS strategy, the shortage or the poor quality of the anti-tuberculosis drugs, and the poor therapeutic adherence of the patients to the prescribed regimens. Consultation with tuberculosis experts (e.g., consilium) is crucial to tailor the best anti-tuberculosis therapy. New therapeutic options are necessary: bedaquiline and delamanid seem promising drugs; in particular, during the development phase they demonstrated a protective effect against the emergence of further resistances towards the backbone drugs. In the recent past, other antibiotics have been administered off-label: the most relevant efficacy, safety, and tolerability profile was proved in linezolid-, meropenem/clavulanate-, cotrimoxazole-containing regimens. New research and development activities are needed in the diagnostic, therapeutic, preventive fields. PMID:24792579

Sotgiu, Giovanni; Migliori, Giovanni Battista

2014-04-30

152

TFPI-2 downregulates multidrug resistance protein in 5-FU-resistant human hepatocellular carcinoma BEL-7402/5-FU cells.  

Science.gov (United States)

Tissue factor pathway inhibitor-2 (TFPI-2) is known to induce apoptosis and to suppress tumor metastasis in several types of cancer cells. However, there is little known about its reversal effect on chemoresistant tumor cells. This study investigated the effect of TFPI-2 in 5-fluorouracil (5-FU)-resistant human hepatocellular cancer BEL-7402/5-FU cells in vitro. We constructed TFPI-2 overexpression BEL-7402/5-FU cell lines and explored resistance index (RI) of 5-FU, function of the P-glycoprotein (P-gp) efflux pump, and the mRNA and protein expression of drug resistance gene, including multidrug resistance gene (MDR1), lung-resistance protein (LRP), multidrug resistance-associated protein (MRP1), glutathione-S-transferase-? (GST-?), excision repair cross-complementing gene 1 (ERCC1), and p38 phosphorylation. We found that TFPI-2 improved the RI of 5-FU and inhibited P-gp function. Western blotting and real-time PCR revealed that TFPI-2 also decreased mRNA and protein expression of MDR1, LRP, MRP1, GST-?, and ERCC1, whereas p38 phosphorylation was increased. We considered that TFPI-2 reduces 5-FU resistance in BEL-7402/5-FU cells, and the mechanism appears to involve p38-mediated downregulation of drug resistance gene expression such as MDR1, LRP, MRP1, GST-?, and ERCC1. PMID:23125179

Lu, Fei; Hou, Yong-Qiang; Song, Ying; Yuan, Zheng-Jiang

2013-01-01

153

Study of tea polyphenol as a reversal agent for carcinoma cell lines' multidrug resistance (study of TP as a MDR reversal agent)  

International Nuclear Information System (INIS)

The aim of this study was to examine MDR1 expression product P-glycoprotein (Pgp) and study the effect and mechanism of tea polyphenol (TP) in reversion of multidrug resistance (MDR) in carcinoma cell lines. Immunocytochemical method was used for qualitative detection of Pgp. A comparative study of cytotoxicity and multidrug resistance reversion effect was made by MTT assay for tea polyphenol and quinidine in MCF-7 and MCF-7/Adr cell lines. The multidrug resistance reversion effect and mechanism were studied by measuring the uptake of 99mTc-tetrofosmin in the carcinoma cell lines. (1) The Pgp overexpression in MCF-7/Adr cells was found to be strong positive, while the Pgp expression of MCF-7 was negative. (2) Although both tea polyphenol and quinidine could not remarkably change the toxicity of adriamycin to MCF-7, they could improve the sensitivity of MCF-7/Adr to adriamycin. The reversion index of tea polyphenol and quinidine was 3 and 10 respectively. (3) The cellular uptake of 99mTc-tetrofosmin was remarkably lower in MCF-7/Adr than in MCF-7. The uptake of 99mTc-tetrofosmin in MCF-7/Adr exhibited a 4, 13, 16 fold increase in the presence of 200, 400 and 500 ?g/ml of tea polyphenol respectively. The uptake of 99mTc-tetrofosmin in MCF-7/Adr exhibited only a 4-fold increase in the presence of 200 ?M of quinidine. Immunocytochemistry can detect P-glycoprotein expression level qualitatively. Tea polyphenol is not only an antively. Tea polyphenol is not only an anti-tumor agent, but also a multidrug resistant modulator similar to quinidine. The multidrug resistance reversion mechanism of tea polyphenol seems to be its inhibition of the activity of P-glycoprotein. Tea polyphenol has the advantage of very low toxicity in tumor treatment

154

Multidrug resistant malaria in splenectomized patient  

Directory of Open Access Journals (Sweden)

Full Text Available Malaria is a dangerous infection in splenectomized individuals. In endemic areas, managing malaria in such individuals is a clinical challenge. In the tropics, death from malaria after splenectomy has been reported, but no formal study has been undertaken. Here we discuss a case of multidrug resistant malaria in a splenectomized patient, managed by antimalarial drugs and exchange transfusion with a successful outcome.

Tauro L

2006-01-01

155

Chromosomal Instability Confers Intrinsic Multidrug Resistance  

DEFF Research Database (Denmark)

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. Identification of distinct therapeutic agents that target tumor karyotypic complexity has important clinical implications. To identify distinct therapeutic approaches to specifically limit the growth of CIN tumors, we focused on a panel of colorectal cancer (CRC) cell lines, previously classified as either chromosomally unstable (CIN+) or diploid/near-diploid (CIN-), and treated them individually with a library of kinase inhibitors targeting components of signal transduction, cell cycle, and transmembrane receptor signaling pathways. CIN+ cell lines displayed significant intrinsic multidrug resistance compared with CIN- cancer cell lines, and this seemed to be independent of somatic mutation status and proliferation rate. Confirming the association of CIN rather than ploidy status with multidrug resistance, tetraploid isogenic cells that had arisen from diploid cell lines displayed lower drug sensitivity than 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) 2011 AACR.

Lee, Alvin J. X.; Endesfelder, David

2011-01-01

156

P53 protein expression in human multidrug-resistant CEM lymphoblasts.  

Science.gov (United States)

A role for p53 in the regulation of multidrug-resistance (MDR) has been postulated as wild-type p53 suppresses and mutant p53 specifically activates the mdr1 promoter. Moreover, changes in p53 expression and/or functions could be implicated in drug resistance. As the parental lymphoblastic CCRF-CEM cell line has been described as expressing a mutated form of p53, we have examined p53 and mdm2 protein levels in the human multidrug-resistant CEM-VLB cell line variant. These drug-resistant CEM-VLB cells, which have increased expressions of mdr1 and P-glycoprotein, displayed p53 and mdm2 protein expressions similar to those observed in their sensitive CCRF-CEM counterparts. Treatment of these drug-resistant cells with non-toxic doses of the resistance-inducing drug vinblastin induced a strong increase in p53 protein and mRNA but was ineffective on mdm2 protein expression, or mdr1 mRNA expression. These data indicate that mutant p53 protein was not overexpressed in these MDR cells. This overexpression could be induced by microtubule-active drug treatment, but, as previously observed in other sensitive cell lines, mutant p53 from these MDR cells was unable to positively regulate mdm2 gene product expression. PMID:9112432

Rafki, N; Liautaud-Roger, F; Devy, L; Trentesaux, C; Dufer, J

1997-02-01

157

Study of multidrug resistance and radioresistance  

International Nuclear Information System (INIS)

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

158

Study of multidrug resistance and radioresistance  

Energy Technology Data Exchange (ETDEWEB)

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.

Kang, Yoon Koo; Yoo, Young Do

1999-04-01

159

Down-regulation of c-fos by shRNA sensitizes adriamycin-resistant MCF-7/ADR cells to chemotherapeutic agents via P-glycoprotein inhibition and apoptosis augmentation.  

Science.gov (United States)

Multidrug resistance (MDR) is a major hurdle in the treatment of cancer. Research indicated that the main mechanisms of most cancers included so-called "pump" (P-glycoprotein, P-gp) and "non-pump" (apoptosis) resistance. Identification of novel signaling molecules associated with both P-gp and apoptosis will facilitate the development of more effective strategies to overcome MDR in tumor cells. Since the proto-oncogene c-fos has been implicated in cell adaptation to environmental changes, we analyzed its role in mediating "pump" and "non-pump" resistance in MCF-7/ADR, an adriamycin (ADR)-selected human breast cancer cell line with the MDR phenotype. Elevated expression of c-fos in MCF-7/ADR cells and induction of c-fos by ADR in the parental drug-sensitive MCF-7 cells suggested a link between c-fos and MDR phenotype. Down-regulation of c-fos expression via shRNA resulted in sensitization of MCF-7/ADR cells to chemotherapeutic agents, including both P-gp and non-P-gp substrates. Further results proved that c-fos down-regulation in MCF-7/ADR cells resulted in decreased P-gp expression and activity, enhanced apoptosis, and altered expression of apoptosis-associated proteins (i.e., Bax, Bcl-2, p53, and PUMA). All above facts indicate that c-fos is involved in both P-gp- and anti-apoptosis-mediated MDR of MCF-7/ADR cells. Based on these results, we propose that c-fos may represent a potential molecular target for resistant cancer therapy, and suppressing c-fos gene expression may therefore be an effective means to temper breast cancer cell's MDR to cytotoxic chemotherapy. PMID:23494858

Shi, Ruizan; Peng, Hongwei; Yuan, Xiangfei; Zhang, Xiuli; Zhang, Yanjun; Fan, Dongmei; Liu, Xuyi; Xiong, Dongsheng

2013-08-01

160

Differential chemosensitization of P-glycoprotein overexpressing K562/Adr cells by withaferin A and Siamois polyphenols  

OpenAIRE

Abstract Background Multidrug resistance (MDR) is a major obstacle in cancer treatment and is often the result of overexpression of the drug efflux protein, P-glycoprotein (P-gp), as a consequence of hyperactivation of NF?B, AP1 and Nrf2 transcription factors. In addition to effluxing chemotherapeutic drugs, P-gp also plays a specific role in blocking caspase-dependent apoptotic pathways. One feature that cytotoxic treatments of cancer have in common is activation of the transcription factor...

Gerlo Sarah; Zhokhov Sergey; Palagani Ajay; Poompimon Wilart; Mankhetkorn Samlee; Suttana Wipob; Haegeman Guy; Berghe Wim

2010-01-01

161

Synthesis of poly[N-(2-hydroxypropyl)methacrylamide] conjugates of inhibitors of the ABC transporter that overcome multidrug resistance in doxorubicin-resistant P388 cells in vitro.  

Czech Academy of Sciences Publication Activity Database

Ro?. 15, ?. 8 (2014), s. 3030-3043. ISSN 1525-7797 R&D Projects: GA ?R GAP301/12/1254; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61389013 ; RVO:61388971 Keywords : N-(2-hydroxypropyl)methacrylamide copolymers * multidrug resistance * P-glycoprotein inhibitors Subject RIV: CD - Macromolecular Chemistry; FD - Oncology ; Hematology (MBU-M) Impact factor: 5.788, year: 2013

Šubr, Vladimír; Sivák, Ladislav; Koziolová, Eva; Braunová, Alena; Pechar, Michal; Strohalm, Ji?í; Kabešová, Martina; ?íhová, Blanka; Ulbrich, Karel; Ková?, Marek

2014-01-01

162

Terpenoids from Maytenus species and assessment of their reversal activity against a multidrug-resistant Leishmania tropica line.  

Science.gov (United States)

The phytochemical analysis of the root bark extracts of the Chilean Maytenus, M. chubutensis, and M. magellanica (Celastraceae), led to the isolation of one phenolic nortriterpene, 1, and one diterpene with a nor-ent-kaurene skeleton, 2. In addition, four known compounds were isolated, among which compound 3 has been isolated for the first time from a natural source. Their structures were elucidated by spectroscopic methods, including 1D- and 2D-NMR (COSY, ROESY, HSQC, and HMBC) experiments, comparison with data reported in the literature, and chemical correlations. The isolated compounds were assayed for their reversal activity against a multidrug-resistant Leishmania tropica line, overexpressing a P-glycoprotein related transporter. Compound 1 showed moderate multidrug-resistance reversal activity. PMID:22162167

Kennedy, María L; Llanos, Gabriel G; Castanys, Santiago; Gamarro, Francisco; Bazzocchi, Isabel L; Jiménez, Ignacio A

2011-12-01

163

P-glycoprotein activity and biological response  

International Nuclear Information System (INIS)

P-glycoprotein (P-gp) is a transmembrane drug efflux pump encoded by the MDR-1 gene in humans. Most likely P-gp protects organs against endogenous and exogenous toxins by extruding toxic compounds such as chemotherapeutics and other drugs. Many drugs are substrates for P-gp. Since P-gp is also expressed in the blood-brain barrier, P-gp substrates reach lower concentrations in the brain than in P-gp-negative tissues. Failure of response to chemotherapy of malignancies can be due to intrinsic or acquired drug resistance. Many tumors are multidrug resistant (MDR); resistant to several structurally unrelated chemotherapeutic agents. Several mechanisms are involved in MDR of which P-gp is studied most extensively. P-gp extrudes drugs out of tumor cells resulting in decreased intracellular drug concentrations, leading to the MDR phenotype. Furthermore, the MDR-1 gene exhibits several single nucleotide polymorphisms, some of which result in different transport capabilities. P-gp functionality and the effect of P-gp modulation on the pharmacokinetics of novel and established drugs can be studied in vivo by positron emission tomography (PET) using carbon-11 and fluorine-18-labeled P-gp substrates and modulators. PET may demonstrate the consequences of genetic differences on tissue pharmacokinetics. Inhibitors such as calcium-channel blockers (verapamil), cyclosporin A, ONT-093, and XR9576 can modulate the P-gp functionality. With PET the effect of P-gp modulation on the bioavahe effect of P-gp modulation on the bioavailability of drugs can be investigated in humans in vivo. PET also allows the measurement of the efficacy of newly developed P-gp modulators

164

Imaging and Targeted Therapy of Multidrug Resistance. Final Report  

International Nuclear Information System (INIS)

One focus area of DOE Office of Science was the Imaging of Gene Expression in Health and Disease in real time in tissue culture, whole animals and ultimately patients. Investigators of the Molecular Imaging Group, Washington University Medical School, ascribed to this objective and a major focus of this group directly tied into the DOE program through their efforts targeting the multidrug resistance gene (MDR1). Our plans for continuation of the program were to extend and build on this line of investigation, incorporating new molecular tools into our methodology to selectively inhibit MDR1 gene expression with novel modulation strategies. Two approaches were to be pursued: (1) high throughput screening of compounds that disrupted mutant p53 transactivation of the MDR1 promoter, and (2) knockdown of MDR1 messenger RNA with retroviral-mediated delivery of small interfering RNA constructs. These would be combined with our continuing effort to synthesize ligands and examine structure-activity relationships of bis-salicylaldehydes labeled with gallium-68 to generate PET agents for imaging MDR1 P-glycoprotein function. We would be uniquely positioned to correlate therapeutic modulation of MDR1 gene expression and protein function in the same systems in vivo using PET and bioluminescence reporters. Use of animal models such as the mdr1a/1b(-/-) gene deleted mice would also have enabled refined analysis of modulation and tracer pharmacokinetics in vivo. Overall, this DOE program and resultant tools would enable direct monitoring of novel therapeutic strategies and the MDR phenotype in relation to gene expression and protein function in vivo.

165

Predicting P-Glycoprotein-Mediated Drug Transport Based On Support Vector Machine and Three-Dimensional Crystal Structure of P-glycoprotein  

OpenAIRE

Human P-glycoprotein (P-gp) is an ATP-binding cassette multidrug transporter that confers resistance to a wide range of chemotherapeutic agents in cancer cells by active efflux of the drugs from cells. P-gp also plays a key role in limiting oral absorption and brain penetration and in facilitating biliary and renal elimination of structurally diverse drugs. Thus, identification of drugs or new molecular entities to be P-gp substrates is of vital importance for predicting the pharmacokinetics,...

Bikadi, Zsolt; Hazai, Istvan; Malik, David; Jemnitz, Katalin; Veres, Zsuzsa; Hari, Peter; Ni, Zhanglin; Loo, Tip W.; Clarke, David M.; Hazai, Eszter; Mao, Qingcheng

2011-01-01

166

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

Directory of Open Access Journals (Sweden)

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.

Lin Ge

2010-07-01

167

Yeast ABC proteins involved in multidrug resistance.  

Science.gov (United States)

Pleiotropic drug resistance is a complex phenomenon that involves many proteins that together create a network. One of the common mechanisms of multidrug resistance in eukaryotic cells is the active efflux of a broad range of xenobiotics through ATP-binding cassette (ABC) transporters. Saccharomyces cerevisiae is often used as a model to study such activity because of the functional and structural similarities of its ABC transporters to mammalian ones. Numerous ABC transporters are found in humans and some are associated with the resistance of tumors to chemotherapeutics. Efflux pump modulators that change the activity of ABC proteins are the most promising candidate drugs to overcome such resistance. These modulators can be chemically synthesized or isolated from natural sources (e.g., plant alkaloids) and might also be used in the treatment of fungal infections. There are several generations of synthetic modulators that differ in specificity, toxicity and effectiveness, and are often used for other clinical effects. PMID:24297686

Piecuch, Agata; Ob??k, Ewa

2014-03-01

168

Multidrug-resistant breast cancer: current perspectives  

Directory of Open Access Journals (Sweden)

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

Martin HL

2014-01-01

169

Inhibition of glutathione peroxidase mediates the collateral sensitivity of multidrug-resistant cells to tiopronin.  

Science.gov (United States)

Multidrug resistance (MDR) is a major obstacle to the successful chemotherapy of cancer. MDR is often the result of overexpression of ATP-binding cassette transporters following chemotherapy. A common ATP-binding cassette transporter that is overexpressed in MDR cancer cells is P-glycoprotein, which actively effluxes drugs against a concentration gradient, producing an MDR phenotype. Collateral sensitivity (CS), a phenomenon of drug hypersensitivity, is defined as the ability of certain compounds to selectively target MDR cells, but not the drug-sensitive parent cells from which they were derived. The drug tiopronin has been previously shown to elicit CS. However, unlike other CS agents, the mechanism of action was not dependent on the expression of P-glycoprotein in MDR cells. We have determined that the CS activity of tiopronin is mediated by the generation of reactive oxygen species (ROS) and that CS can be reversed by a variety of ROS-scavenging compounds. Specifically, selective toxicity of tiopronin toward MDR cells is achieved by inhibition of glutathione peroxidase (GPx), and the mode of inhibition of GPx1 by tiopronin is shown in this report. Why MDR cells are particularly sensitive to ROS is discussed, as is the difficulty in exploiting this hypersensitivity to tiopronin in the clinic. PMID:24930045

Hall, Matthew D; Marshall, Travis S; Kwit, Alexandra D T; Miller Jenkins, Lisa M; Dulcey, Andrés E; Madigan, James P; Pluchino, Kristen M; Goldsborough, Andrew S; Brimacombe, Kyle R; Griffiths, Gary L; Gottesman, Michael M

2014-08-01

170

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

Science.gov (United States)

Drug efflux transporter P-glycoprotein plays an important role in cancer chemotherapy. The nuclear factor-?B (NF-?B) transcription factors play critical roles in development and progression of cancer. In this study, the effects of natural compounds that can inhibit NF-?B 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)-? stimulated NF-?B 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-?B 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-?B activation, and may become useful to enhance the efficacy of cancer chemotherapy. PMID:25776492

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

2015-03-01

171

Trends in multidrug-resistant tuberculosis  

Directory of Open Access Journals (Sweden)

Full Text Available Multidrug-resistant tuberculosis (MDR-TB is an increasing global problem. The extent and burden of MDR-TB varies significantly from country to country and region to region. Globally, about three per cent of all newly diagnosed patients have MDR-TB and the proportion is higher in patients who had previously received anti-tuberculosis (anti-TB treatment reflecting the failure of programs designed to ensure complete cure of patients with tuberculosis. The management of MDR-TB is a challenge that should be undertaken by experienced clinicians at centers equipped with reliable laboratory services and implementation of DOTS-Plus strategy.

I. M. F. Dias-Baptista

2008-01-01

172

Role of p-glycoprotein expression in predicting response to neoadjuvant chemotherapy in breast cancer-a prospective clinical study  

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Full Text Available Abstract Background Neoadjuvant chemotherapy (NACT is an integral part of multi-modality approach in the management of locally advanced breast cancer. It is vital to predict response to chemotherapy in order to tailor the regime for a particular patient. The prediction would help in avoiding the toxicity induced by an ineffective chemotherapeutic regime in a non-responder and would also help in the planning of an alternate regime. Development of resistance to chemotherapeutic agents is a major problem and one of the mechanisms considered responsible is the expression of 170-k Da membrane glycoprotein (usually referred to as p-170 or p-glycoprotein, which is encoded by multidrug resistance (MDR1 gene. This glycoprotein acts as an energy dependent pump, which actively extrudes certain families of chemotherapeutic agents from the cells. The expression of p-glycoprotein at initial presentation has been found to be associated with refractoriness to chemotherapy and a poor outcome. Against this background a prospective study was conducted using C219 mouse monoclonal antibody specific for p-glycoprotein to ascertain whether pretreatment detection of p-glycoprotein expression could be utilized as a reliable predictor of response to neoadjuvant chemotherapy in patients with breast cancer. Patients and methods Fifty cases of locally advanced breast cancer were subjected to trucut® biopsy and the tissue samples were evaluated immunohistochemically for p-glycoprotein expression and ER, PR status. The response to neoadjuvant chemotherapy was assessed clinically and by using ultrasound after three cycles of FAC regime (cyclophosphamide 600 mg/m2, Adriamycin 50 mg/m2, 5-fluorourail 600 mg/m2 at an interval of three weeks. The clinical response was correlated with both the pre and post chemotherapy p-glycoprotein expression. Descriptive studies were performed with SPSS version 10. The significance of correlation between tumor response and p-glycoprotein expression was determined with chi square test. Results A significant relationship was found between the pretreatment p-glycoprotein expression and clinical response. The positive p-glycoprotein expression was associated with poor clinical response rates. When the clinical response was correlated with p-glycoprotein expression, a statistically significant negative correlation was observed between the clinical response and p- glycoprotein expression (p Conclusion The study concluded that pretreatment p-glycoprotein expression predicts and indicates a poor clinical response to NACT. Patients with positive p-glycoprotein expression before initiation of NACT were found to be poor responders. Thus pretreatment detection of p-glycoprotein expression may be utilized, as a reliable predictor of response to NACT in patients with breast cancer The chemotherapy induced p-glycoprotein positivity observed in the study could possibly explain the phenomenon of acquired chemoresistance and may also serve as an intermediate end point in evaluating drug response particularly if the adjuvant therapy is planned with the same regime.

Bhatia Ashima

2005-09-01

173

Correlation between uptake of 99TcM-MIBI and multidrug resistant proteins of breast cancer  

International Nuclear Information System (INIS)

Objectives: To assess the correlation between 99Tcm-MIBI uptake and the expression level of multidrug resistant proteins of breast cancer. Methods: Thirty patients with infiltrating ductal carcinoma were enrolled in this study. 99Tcm-MIBI scintigraphy were performed at 15 min and 90 min after injecting the tracer. The uptake of 99Tcm-MIBI were evaluated as tumor over background ratio with region of interest technique. Such indexes as early uptake ratio (EUR), delay uptake ratio (DUR) and retention index (RI) were calculated respectively. P-gp (P-glycoprotein) and MRP (multidrug resistant-associated protein) expression in surgically resected tumors were investigated by immunohistochemistry. Immunohistochemistry HPIAS-1000 image analysis system was used to determined the level of P-gp and MRP expression. The difference of P-gp and MRP level in the group with RI ? 0 and the group with RI99Tcm-MIBI on delayed scans in breast cancer. The uptake of 99Tcm-MIBI may be not related to the levels of MRP expression. Thus 99Tcm-MIBI scintigraphy may predict the MDR development which associated with P-gp expression in breast carcinoma. (authors)

174

Multidrug resistance-associated ABC transporters - too much of one thing, good for nothing.  

Science.gov (United States)

Abstract Overexpression of ATP-binding cassette (ABC) transporters in cancer cells results in multidrug resistance (MDR) which leads to unsuccessful chemotherapy. The most important MDR-associated members of ABC superfamily are ABC B1/P-glycoprotein/MDR1, ABC C1/multidrug resistance associated protein 1 (MRP1), and ABC G2/BCRP. This study is not only focused on function, substrates, and localization of these popular proteins but also on other ABC C family members such as ABC C2-6/MRP2-6 and ABC C7/CFTR. Current research is mainly oriented on the cancer-promoting role of these proteins, but important lessons could also be learned from the physiological roles of these proteins or from polymorphisms affecting their function. Thorough knowledge of structure and detailed mechanism of efflux can aid in the discovery of new chemotherapy targets in the future. Although the best way on how to deal with MDR would be to prevent its development, we describe some new promising strategies on how to conquer both inherited and induced MDRs. PMID:25436540

Prochazkova, Jirina; Lanova, Martina; Pachernik, Jiri

2012-08-01

175

Expression and clinical significance of multidrug resistance proteins in brain tumors  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background To investigate the mechanisms of multidrug resistance of brain tumors, to identify the site of cellular expression of P-gp in human brains in situ and to morphologically determine whether an association may exist between P-gp and caveolin-1. Methods Immunohistochemistry was used to detect the expression and location of P-glycoprotein (P-gp, Multidrug resistance-associated protein (MDR, Lung resistance-related protein (LRP, Topoisomerase II (Topo II and Glutathione-S-? (GST-? in 30 patient tumor tissues and 5 normal brain tissues. The sections were subjected to double labeling for P-gp (TRITC labeled and caveolin-1 (FITC labeled. The location and characteristics of expression of the two proteins in the blood brain barrier(BBB was observed using a laser scanning microscope. Results High expression of P-gp was detected in vessel walls and the tissue surrounding the vessels. However, expression of P-gp was low in tumor cells. The expression of the other 4 multidrug resistance proteins was not observed in the vessel walls. Laser scanning microscopy showed P-gp and caveolin-1 co-expression: the two proteins co-localized either in the luminal endothelial compartment or at the border of the luminal/abluminal compartments. Conclusion Chemotherapeutics drugs are interrupted in the end-feet of neuroepithelial cells of the BBB by P-gp, which weakens the chemotherapeutic effect. P-gp marks the BBB, and the transporter is localized in the luminal endothelial compartment where it co-localizes with caveolin-1.

Guo Zhenhua

2010-09-01

176

Quantitative analysis of MDR1 (multidrug resistance) gene expression in human tumors by polymerase chain reaction  

International Nuclear Information System (INIS)

The resistance of tumor cells ot chemotheraprutic drugs is a major obstacle to successful cancer chemotherapy. In human cells, expression of the MDR1 gene, encoding a transmembrane efflux pump (P-glycoprotein), leads to decreased intracellular accumulation and resistance to a variety of lipophilic drugs (multidrug resistance; MDR). The levels of MDR in cell lines selected in bitro have been shown to correlate with the steady-state levels of MDR1 mRNA and P-glycoprotein. In cells with a severalfold increase in cellular drug resistance, MDR1 expression levels are close to the limits of detection by conventional assays. MDR1 expression has been frequently observed in human tumors after chemotherapy and in some but not all types of clinically refactory tumors untreated with chemotherapeutic drugs. The authors have devised a highly sensitive, specific, and quantitative protocol for measuring the levels of MDR1 mRNA in clincal samples, based on the polymerase chain reaction. They have used this assay to measure MDR1 gene expression in MDR cell lines and >300 normal tissues, tumor-derived cell lines, and clinical specimens of untreated tumors of the types in which MDR1 expression was rarely observed by standard assays. Low levels of MDR1 expression were found by polymerase chain reaction in most solid tumors and leukemias tested. The frequency of samples without detectable MDR1 expression varied among different types of tumors; MDR1-negative samples were ost common among tumnegative samples were ost common among tumor types known to be relatively responsive to chemotherapy

177

Noninvasive functional imaging of P-glycoprotein-mediated doxorubicin resistance in a mouse model of hereditary breast cancer to predict response, and assign P-gp inhibitor sensitivity  

Energy Technology Data Exchange (ETDEWEB)

Using a ''spontaneous'' mammary mouse tumor model we set out to develop diagnostic approaches for non-invasive P-glycoprotein (P-gp) staging and response prediction. {sup 99m}Tc-MIBI efflux rates were measured using a gamma camera in three Brca1 {sup -/-}; p53 {sup -/-} mouse mammary tumors that have different Mdr1a/b expression levels. The efflux rates were quantified in the 10-30-min period after injection. In addition to the P-gp-mediated efflux measurements in untreated tumors, efflux measurements were performed in the presence of the P-gp inhibitor tariquidar. Volumetric doxorubicin response patterns for the different tumors were determined and correlated with the efflux rates. Combined pre- and post-inhibitor treatment imaging of P-gp-mediated efflux correlated with Mdr1a/b expression: basal (0.0026, p = 0.16), 3-fold Mdr1a/b (0.0074, p = 0.02), and 17-fold Mdr1a and 46-fold Mdr1b (0.012, p = 0.002). Based on the doxorubicin response of these tumors, we generated a computer-aided diagnosis model that predicts the likelihood of drug resistance. Quantified {sup 99m}Tc-MIBI efflux has potential to: (1) noninvasively assign Mdr1 expression levels, (2) predict the therapeutic impact of a P-gp inhibitor, and (3) noninvasively assess the probability of drug resistance. (orig.)

Leeuwen, Fijs W.B. van; Buckle, Tessa; Gilhuijs, Kenneth G.A. [The Netherlands Cancer Institute - Antoni van Leeuwenhoek Hospital, Departments of Radiology and Nuclear Medicine, Amsterdam (Netherlands); Kersbergen, Ariena; Rottenberg, Sven [The Netherlands Cancer Institute - Antoni van Leeuwenhoek Hospital, Department of Molecular Biology, Amsterdam (Netherlands)

2009-03-15

178

A lack of Adriamycin (ADR) resistance in Chinese hamster ovary (CHO) cells overexpressing P-glycoprotein (Pgp) following in vitro exposure to fractionated X-irradiation  

International Nuclear Information System (INIS)

Using x-ray pretreated CHO cells, the authors demonstrated differing accumulation of adriamycin and vincristine in cells overexpressing P-glycoprotein. Response was also varied by the addition of calcium channel antagonist verapamil. (author)

179

Effect of multidrug resistance gene-1(MDR1) expression on in-vitro uptake of Tc-99m sestaMIBI(MIBI) in murine L1210 leukemia cells  

International Nuclear Information System (INIS)

Resistance of malignant tumors to multiple chemotherapeutic agents is a major cause of treatment failure and one of the most important mechanisms of multidrug resistance is an increased expression of plasma membrane P-glycoprotein. P-glycoprotein can recognize and transport a large group of cytotoxic compounds sharing little or no structural or functional similarities, other than being relatively small, hydrophobic and cationic. Recent studies have proved that Tc-99m MIBI is transported by the P-glycoprotein in insect cells with overexpression of recombinant multidrug resistance P-glycoprotein. To demonstrate that Tc-99m MIBI is recognized by the multidrug resistant P-glycoprotein, we have quantitatively measured Tc-99m MIBI uptake in cancer cells with or without expression of MDR1 gene which is responsible for P-glycoprotein. The relationship between Tc-99m MIBI uptake and expression of MDR1 gene was evaluated. Multidrug resistance cell lines were induced from murine leukemia cell line(L1210, mouse lymphocytic leukemia cell, ATCC) with continuous challenging low dose adriamycin (Adr cell) or vincristine (Vcr cell) in culture media. Expression of MDR1 RNA was measured with reverse transcriptase polymerase chain reaction (RT-PCR) using 243 base pair primer (Kizaki et al. Blood 87:725, 1996). Cellular uptake of Tc-99m MIBI was measured at 4 .deg. C and 37 .deg. C condition, and after incubating for 60-min in 37 .deg. C RPMI media with or without 50uM or 200uM verapamil.a with or without 50uM or 200uM verapamil. RT-PCR of Adr cells revealed an intense band corresponding expression of MDR1 RNA, whereas Vcr cells weaker linear band. In contrast, RT-PCR specimen of L1210 did not show MDR1 band. Incubation of cells with Tc-99m MIBI resulted in higher uptake with L1210 than Adr or Vcr cells in either 4 .deg. C (37% L1210 vs 17% Adr or 9% Vcr, p<0.05 respectively) or 37 .deg. C (48% vs 25% or 23%, p<0.01 respectively). In the presence of verapamil, known reverser of PgP functions, incubation with verapamil resulted in increased Tc-99m MIBI uptake in Adr cell line (from 25% to 29% with 50uM or 45% with 200uM) and Vcr cell line(from 23% to 27% with 50uM or 35% with 200uM). Tc-99m MIBI uptake was not changed with verapamil in L1210 cells. These results demonstrate that MDR1 gene expressing cell lines were effectively induced in in-vitro and Tc-99m MIBI is a transporter substrate recognized by the MDR1 P-glycoprotein. Tc-99m MIBI may be useful for characterizing P-glycoprotein expression in leukemic cells in vitro

180

Quinolones and multidrug-resistant tuberculosis.  

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The prevalence of initial resistance of multidrug-resistant tuberculosis (MDR-TB) to at least isoniazid (INH) and rifampicin (RFP) in Thailand during the period 1993-1997 is reported; in this era, trends for INH + RFP + streptomycin (SM) and ethambutol (EMB), INH + RFP + SM or EMB and MDR-TB were stable. The prevalence of acquired MDR-TB is on a slight downward trend, with the latest level at 22.6%. Recommended management of MDR-TB is outlined and advantages and disadvantages of these guidelines discussed. The role of ofloxacin in MDR-TB is presented, with results from a study performed by the Thailand CDC showing that the percentage of strains resistant to ofloxacin was 4.3%, and to ciprofloxacin was 8.3%. The resistance to both ofloxacin and ciprofloxacin was very low at 1.4%. The percentage of cross-resistance between these fluoroquinolones was also low; 33% resistant to ofloxacin were also resistant to ciprofloxacin and only 17% of those resistant to ciprofloxacin were also resistant to ofloxacin. Results from a clinical trial evaluating ofloxacin with other drugs for MDR-TB are also reported. The regimen comprised ofloxacin 600 mg/day, pyrazinamide (PZA), two to three months of kanamycin (KM) or amikacin (AMK), para-aminosalicylic acid (PAS) plus EMB or thiacetazone. Drugs were given for 18 months. Follow-up was every three months for two years. Preliminary results revealed that the percentage of acquired MDR-TB resistant to specific agents was as follows: 36% resistant to INH and RFP, 23% resistant to INH, RFP plus EMB, 27% resistant to INH, RFP and SM, and 14% resistant to all four of these agents (INH + RFP + SM + EMB). All isolates were sensitive to ofloxacin. At one month of treatment, sputum culture conversion was approximately 25%, climbing to 93% by nine months of treatment. Treatment with ofloxacin in a combined regimen achieved a success rate of 78%. The role of quinolones in preventing TB in MDR-TB contacts is also discussed. PMID:10449893

Maranetra, K N

1999-01-01

181

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

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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. PMID:16277030

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

2005-01-01

182

In vitro antileukaemic activity of extracts from berry plant leaves against sensitive and multidrug resistant HL60 cells.  

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The aim of the present study was to determine in vitro antileukaemic activity of extracts obtained from selected berry plant leaves (Fragaria x ananassa Duch. cv Elsanta, raspberry Rubus ideus L. cv Polana and blueberry Vaccinium corymbosum L. cv Bluecrop) against promyelocytic HL60 cell line and its multidrug resistant sublines exhibiting two different MDR phenotypes: HL60/VINC (overexpressing P-glycoprotein) and HL60/DOX (overexpressing MRP1 protein). It was found that the blueberry extract was the most efficient against sensitive HL60 cell line (about 2-fold more active than strawberry and raspberry extracts) but presented much lower activity towards resistant cells. In contrast, strawberry and raspberry extracts exhibited the high cytotoxic activity against sensitive leukaemia HL60 cell line as well as its MDR sublines. The values of resistance factor (RF) found for these extracts were very low lying in the range 0.32/2.0. PMID:16039042

Skupie?, Katarzyna; Oszmia?ski, Jan; Kostrzewa-Nowak, Dorota; Tarasiuk, Jolanta

2006-05-18

183

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

184

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

International Nuclear Information System (INIS)

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.

185

Evidence of p-glycoprotein sequence diversity in cyathostomins.  

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P-glycoproteins (Pgps) are adenosine triphosphate-binding transporter proteins thought to be associated with multi-drug resistance in mammals and protozoans and have been suggested to be involved in the mechanism of ivermectin (IVM) resistance in Haemonchus contortus. Until now, resistance to IVM has not been reported in cyathostomins in horses in spite of its widespread and frequent use. Reasons for this might be differences in the molecular mechanism of the development of resistance. Based on this hypothesis, the present study was carried out to find homologues of Pgp in cyathostomins. A 416-bp polymerase chain reaction (PCR) product was generated using complementary DNA (cDNA) of Cylicocyclus elongatus and Cylicocyclus insigne and degenerate primers, located in the conserved Pgp nucleotide-binding domains. Resulting PCR products showed interspecific nucleotide and amino acid sequence identities of 73.3 and 76.8%, respectively. Specific primers were designed based on the Cc. elongatus sequence, and a PCR product of 268-bp was amplified from cDNA of single adults of Cylicocyclus radiatus, Cc. insigne, Cylicocyclus nassatus, Cc. elongatus, Cylicostephanus hybridus (2 individuals), Cylicostephanus goldi, Cyathostomum pateratum, Cyathostomum coronatum, and Cyathostomum catinatum. Two clusters of sequences were found representing 2 different internucleotide-binding domains (IBDs). A further distinct IBD is represented by the 416-bp PCR product of Cc. insigne. Therefore, a total of 3 clearly different sequences of the IBD were cloned and sequenced, suggesting that at least 2 Pgp genes exist in cyathostomins. PMID:15562598

Drogemuller, Michaela; Schnieder, T; von Samson-Himmelstjerna, G

2004-10-01

186

The imaging feature of multidrug-resistant tuberculosis  

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Objective: To evaluate the imaging features of multidrug-resistant tuberculosis by collecting multidrug-resistant tuberculosis verified by test of drug-sensitivity, which defined as resistance to three anti-tuberculosis drugs. Methods:Fifty-one cases of multidrug-resistant tuberculosis were categorized as group of observed, and 46 cases of drug sensitive tuberculosis were categorized as control. Cultures were positive for Mycobacterium tuberculosis in all cases with no other illness such as diabetes mellitus. All patients had chest radiographs available for review, while 64 cases had tomography and 30 cases had CT during the same time. All images were analyzed by three of the radiologists, disagreement among them was discussed and a consensus was reached. Results: There was no difference in the distribution of lesions between the multidrug-resistant tuberculosis group and control group. However, the radiological findings in the multidrug-resistant tuberculosis group were significantly more common than in control group, such as multiple nodules (10 cases), disseminated foci (23 cases), cavity (9 cases), and complications (10 cases). Comparing the dynamic cases, deteriorating cases were more commonly seen in observed group than in control group, while improved cases were less in observed group than in control group. Conclusion: Multidrug-resistant tuberculosis is the most serious tuberculosis, which is characterized with significant activity, more disseminated foci, cavcant activity, more disseminated foci, cavity, and complications. The lesion deteriorated while correct anti-tuberculosis treatment is applied. (authors)

187

Multidrug resistant yeasts in synanthropic wild birds  

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Full Text Available Abstract Background The aim of this study was to investigate the presence of multidrug resistant yeasts in the faeces of synanthropic wild birds from the Bangsar suburb of Kuala Lumpur. Methods Species characterisations of yeast isolates and determinations of antimycotic susceptibility profiles were undertaken using the commercial characterization kit, Integral System Yeasts Plus (Liofilchem, Italy. Results Fourteen species of yeasts were detected in the bird faecal samples.Candida albicans was present in 28.89% of bird faecal samples, Candida krusei (13.33%, Candida tropicalis (4.44%, Candida glabrata (4.44%, Candida parapsilosis (2.22%, Candida lambica (2.22%, Candida stellatoidea (2.22%, Candida rugosa (2.22% and Candida lusitaniae (2.22%. Amongst the non-candidal yeast isolates, Cryptococcus laurentii was present in 6.67% of bird faecal samples, Cryptococcus uniguttulatus (4.44%, Saccharomyces cerevisiae (4.44%, Trichosporon pullulans (2.22%, Trichosporon pullulans/Cryptococcus albidus (8.89% and Rhodotorula rubra/Rhodotorula glutinis (4.44%. Of the isolated yeasts, 18.1% (or 26/144 were found to be resistant to all 11 antimycotic agents they were tested against i.e. Nystatin, Amphotericin B, Flucytosine, Econazole, Ketoconazole, Clotrimazole, Miconazole, Itraconazole, Voriconazole, Fluconazole 16 and Fluconazole 64. 45.8% (or 66/144 of the bird faecal yeast isolates were resistant to four or more of the 11 antimycotic agents they were tested against. Conclusions This finding is of public health significance as these synanthropic wild birds may be reservoirs for transmission of drug resistant yeast infections to humans.

Somanath Sushela

2010-03-01

188

Chemosensitivity of prostate cancer cell lines and expression of multidrug resistance-related proteins.  

Science.gov (United States)

The aim of this study was to obtain insight into the role of the multidrug resistance (MDR) phenomenon in hormone-independent progressive prostate cancer. Using immunocytochemistry and Western blotting we determined the expression of P-glycoprotein (Pgp), multidrug resistance-associated protein (MRP), glutathione-S-transferase-pi (GST-pi), Bcl-2, Bax, topoisomerase (Topo) I, II alpha and II beta in the human prostate cancer cell lines PC3, TSU-Pr1, DU145 and LNCaP derivatives LNCaP-R, LNCaP-LNO and LNCaP-FGC. Proliferative activity was assessed by immunocytochemistry. MTT assays were used to determine the sensitivity to etoposide, doxorubicin and vinblastin. Pgp was not expressed in any of the cell lines. MRP was variably expressed. GST-pi was expressed in TSU-Pr1, PC3 and DU145. The expression of Bcl-2 was restricted to TSU-Pr1, whereas Bax was found in all cell lines. Topo II alpha was expressed at the highest level in the rapidly proliferating cell lines TSU-Pr1 and DU145. Topo I and II beta were equally expressed. Resistance profiles varied among the cell lines, with TSU-Pr1 being the most sensitive and LNCaP-LNO relatively resistant. Multiple MDR proteins were expressed in prostate cancer cell lines and may well influence response to chemotherapy. Future functional studies, using chemo-selected MDR models, may further help to determine the mechanism or combination of mechanisms underlying the resistance of prostate cancer to chemotherapy. PMID:10492644

van Brussel, J P; van Steenbrugge, G J; Romijn, J C; Schröder, F H; Mickisch, G H

1999-04-01

189

The Assembly Motif of a Bacterial Small Multidrug Resistance Protein*  

OpenAIRE

Multidrug transporters such as the small multidrug resistance (SMR) family of bacterial integral membrane proteins are capable of conferring clinically significant resistance to a variety of common therapeutics. As antiporter proteins of ?100 amino acids, SMRs must self-assemble into homo-oligomeric structures for efflux of drug molecules. Oligomerization centered at transmembrane helix four (TM4) has been implicated in SMR assembly, but the full complement of residu...

Poulsen, Bradley E.; Rath, Arianna; Deber, Charles M.

2009-01-01

190

Lapatinib Antagonizes Multidrug Resistance–Associated Protein 1–Mediated Multidrug Resistance by Inhibiting Its Transport Function  

Science.gov (United States)

Lapatinib, a tyrosine kinase inhibitor, is used in the treatment of advanced or metastatic breast cancer overexpressing human epidermal receptor 2 (HER2). Lapatinib can modulate the function of ATP-binding cassette (ABC) transporters (ABCB1 and ABCG2), which are the major mechanism responsible for multidrug resistance (MDR) in cancer. In this study, we investigated the effect of lapatinib on multidrug resistance–associated protein 1 (MRP1 [ABCC1]), MRP2 (ABCC2), MRP4 (ABCC4) and lung relative resistance protein (LRP) drug efflux pumps. We demonstrated that lapatinib could enhance the efficacy of conventional chemotherapeutic agents in MRP1-overexpressing cells in vitro and in vivo, but no effect in MRP2-, MPR4- and LRP-overexpressing cells. Furthermore, lapatinib significantly increased the accumulation of rhodamine 123 (Rho123) and doxorubicin (DOX) in MRP1-overexpressing cells. However, lapatinib did not alter the protein or mRNA expression levels of MRP1. Further studies showed that the level of phosphorylation of AKT and extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) were not altered at the indicated concentrations of lapatinib. In conclusion, lapatinib enhanced the efficacy of conventional chemotherapeutic agents in MRP1-overexpressing cells by inhibiting MRP1 transport function without altering the level of AKT or ERK1/2 phosphorylation. These findings will encourage the clinical research of lapatinib combined with conventional chemotherapeutic drugs in MRP1-overexpressing cancer patients. PMID:25105301

Ma, Shao-lin; Hu, Ya-peng; Wang, Fang; Huang, Zhen-cong; Chen, Yi-fan; Wang, Xiao-kun; Fu, Li-wu

2014-01-01

191

Bypassing multidrug resistance in human breast cancer cells with lipid/polymer particle assemblies  

Directory of Open Access Journals (Sweden)

Full Text Available Bo Li1, Hui Xu2, Zhen Li1, Mingfei Yao1, Meng Xie1, Haijun Shen1, Song Shen1, Xinshi Wang1, Yi Jin11College of Pharmaceutical sciences, Zhejiang University, Hangzhou, 2No. 202 Hospital of People's Liberation Army, Shenyang, ChinaBackground: Multidrug resistance (MDR mediated by the overexpression of adenosine triphosphate (ATP-binding cassette (ABC transporters, such as P-glycoprotein (P-gp, remains one of the major obstacles to effective cancer chemotherapy. In this study, lipid/particle assemblies named LipoParticles (LNPs, consisting of a dimethyldidodecylammonium bromide (DMAB-modified poly(lactic-co-glycolic acid (PLGA nanoparticle core surrounded by a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC shell, were specially designed for anticancer drugs to bypass MDR in human breast cancer cells that overexpress P-gp.Methods: Doxorubicin (DOX, a chemotherapy drug that is a P-gp substrate, was conjugated to PLGA and encapsulated in the self-assembled LNP structure. Physiochemical properties of the DOX-loaded LNPs were characterized in vitro. Cellular uptake, intracellular accumulation, and cytotoxicity were compared in parental Michigan Cancer Foundation (MCF-7 cells and P-gp-overexpressing, resistant MCF-7/adriamycin (MCF-7/ADR cells.Results: This study found that the DOX formulated in LNPs showed a significantly increased accumulation in the nuclei of drug-resistant cells relative to the free drug, indicating that LNPs could alter intracellular traffic and bypass drug efflux. The cytotoxicity of DOX loaded-LNPs had a 30-fold lower half maximal inhibitory concentration (IC50 value than free DOX in MCF-7/ADR, measured by the colorimetric cell viability (MTT assay, correlated with the strong nuclear retention of the drug.Conclusion: The results show that this core-shell lipid/particle structure could be a promising strategy to bypass MDR.Keywords: chemotherapy, drug delivery, polymeric nanoparticles, multidrug resistance

Li B

2012-01-01

192

Interaction of drugs of abuse and maintenance treatments with human P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2).  

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Drug interaction with P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) may influence its tissue disposition including blood-brain barrier transport and result in potent drug-drug interactions. The limited data obtained using in-vitro models indicate that methadone, buprenorphine, and cannabinoids may interact with human P-gp; but almost nothing is known about drugs of abuse and BCRP. We used in vitro P-gp and BCRP inhibition flow cytometric assays with hMDR1- and hBCRP-transfected HEK293 cells to test 14 compounds or metabolites frequently involved in addiction, including buprenorphine, norbuprenorphine, methadone, ibogaine, cocaine, cocaethylene, amphetamine, N-methyl-3,4-methylenedioxyamphetamine, 3,4-methylenedioxyamphetamine, nicotine, ketamine, Delta9-tetrahydrocannabinol (THC), naloxone, and morphine. Drugs that in vitro inhibited P-gp or BCRP were tested in hMDR1- and hBCRP-MDCKII bidirectional transport studies. Human P-gp was significantly inhibited in a concentration-dependent manner by norbuprenorphine>buprenorphine>methadone>ibogaine and THC. Similarly, BCRP was inhibited by buprenorphine>norbuprenorphine>ibogaine and THC. None of the other tested compounds inhibited either transporter, even at high concentration (100 microm). Norbuprenorphine (transport efflux ratio approoximately 11) and methadone (transport efflux ratio approoximately 1.9) transport was P-gp-mediated; however, with no significant stereo-selectivity regarding methadone enantiomers. BCRP did not transport any of the tested compounds. However, the clinical significance of the interaction of norbuprenorphine with P-gp remains to be evaluated. PMID:19887017

Tournier, Nicolas; Chevillard, Lucie; Megarbane, Bruno; Pirnay, Stéphane; Scherrmann, Jean-Michel; Declèves, Xavier

2010-08-01

193

Impact of P-glycoprotein and breast cancer resistance protein on the brain distribution of antiepileptic drugs in knockout mouse models.  

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Refractory epilepsy is reportedly associated with an overexpression of ATP-binding cassette transporters such as P-glycoprotein (Pgp) and breast cancer resistance protein (Bcrp). In this study, we examined the contribution of Pgp and Bcrp to the brain distribution of 12 antiepileptic drugs (AEDs) in Mdr1a/1b(-/-) and Mdr1a/1b(-/-)/Bcrp(-/-) mice within a therapeutic concentration range. The blood concentrations were sequentially determined, and the brain concentrations were measured at 60 min after intravenous administration. The plasma concentration profiles for each AED in the Mdr1a/1b(-/-) mice were equivalent to those in the wild-type mice. In contrast, the plasma concentration profiles of phenytoin, lamotrigine, topiramate, tiagabine, and levetiracetam in the Mdr1a/1b(-/-)/Bcrp(-/-) mice were significantly lower than the corresponding ones in the wild-type mice. The brain-to-plasma concentration ratio (Kpbrain) values of phenytoin, topiramate, and tiagabine in the Mdr1a/1b(-/-) mice were significantly higher than the corresponding ones in the wild-type mice. In contrast, the Kpbrain values of phenobarbital, clobazam, zonisamide, gabapentin, tiagabine, and levetiracetam in the Mdr1a/1b(-/-)/Bcrp(-/-) mice were significantly higher than the corresponding ones in Mdr1a/1b(-/-) mice. The Kpbrain values of the 12 AEDs in the Mdr1a/1b(-/-)/Bcrp(-/-) mice, but not wild-type mice, significantly correlated with the corresponding molecular weight values. These findings suggest that both Pgp and Bcrp restrict brain access for several AEDs. Taken together, information on the contribution of each transporter may be useful in the development of strategic treatments of refractory epilepsy. PMID:23588114

Nakanishi, Haruka; Yonezawa, Atsushi; Matsubara, Kazuo; Yano, Ikuko

2013-06-15

194

Molecular and functional characterization of P-glycoprotein in vitro.  

Science.gov (United States)

The blood-brain barrier (BBB) physically and metabolically functions as a neurovascular interface between the brain parenchyma and the systemic circulation, and regulates the permeability of several endogenous substrates and xenobiotics in and out of the central nervous system. Several membrane-associated transport proteins, such as P-glycoprotein (P-gp), multidrug resistance-associated proteins, breast cancer resistance protein, and organic anion transporting polypeptides, have been characterized at the BBB and identified to play a major role in regulating the brain bioavailability of several pharmacological agents. This chapter reviews several well-established techniques for the study of the molecular expression, cellular localization, and functional activity of transport proteins in primary and immortalized cell culture systems of the BBB. In particular, we describe the molecular characterization of P-gp/MDR1 at the transcript level using semiquantitative polymerase chain reaction (PCR), at the protein level using immunoblotting, and at the cellular level using immunofluorescence. In addition, the uptake/efflux and transepithelial flux studies, which characterize P-gp transport activity, are described. PMID:21082379

Chan, Gary N Y; Bendayan, Reina

2011-01-01

195

Development of Extensively Drug-resistant Tuberculosis during Multidrug-resistant Tuberculosis Treatment  

OpenAIRE

Rationale: Extensively drug-resistant (XDR) tuberculosis (TB) may arise in individuals on treatment for multidrug-resistant (MDR) TB. Preventing this amplification of resistance will likely improve clinical outcomes and delay the secondary spread of XDR-TB.

Shin, Sonya S.; Keshavjee, Salmaan; Gelmanova, Irina Y.; Atwood, Sidney; Franke, Molly F.; Mishustin, Sergey P.; Strelis, Aivar K.; Andreev, Yevgeny G.; Pasechnikov, Alexander D.; Barnashov, Alexander; Tonkel, Tamara P.; Cohen, Ted

2010-01-01

196

Secondary combined resistance to the multidrug-resistance-reversing activity of cyclosporin A in the cell line F4-6RADR-CsA.  

Science.gov (United States)

Multidrug-resistant tumor cells can be resensitized by combined application of the selecting cytostatic drug and a chemosensitizer, such as cyclosporin A (CsA) or a calcium channel blocker. Since clinical trials on the circumvention of multidrug resistance (MDR) with chemosensitizers report disparate results, we investigated whether tumor cells of the MDR phenotype can develop additional resistance to the cytostatic chemosensitizer combination. Thus, the Adriamycin(ADR)-selected, P-glycoprotein-positive MDR Friend leukemia cell line F4-6RADR was exposed to stepwise increased concentrations of CsA at a constant level of 0.05 microgram/ml ADR. The initial CsA concentration (plus 0.05 microgram/ml ADR) to inhibit cell growth of F4-6RADR cells by 50% (IC50) was 0.04 microgram/ml. By continuous incubation for more than 6 months, the IC50 for CsA (at constant ADR) was elevated to 3.6 micrograms/ml (90-fold), thus generating the variant F4-6RADR-CsA. The F4-6RADR-CsA cells were cross-resistant for cyclosporin H (CsH), a non-immunosuppressive derivative of CsA. As shown by immunocytochemistry as well as by the polymerase chain reaction and by Western blotting including densitometry, P-glycoprotein was preserved in the F4-6RADR-CsA variant and was expressed at a 4-fold higher level than in F4-6RADR cells. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis analysis could detect no new proteins in F4-6RADR-CsA as compared to F4-6RADR. Interestingly, resistance of F4-6RADR-CsA cells remained reversible for the calcium antagonists verapamil and dihydropyridine B859-35 (dexniguldipine-HCl), indicating that CsA and these compounds interfere with the P glycoprotein function by different pharmacodynamic mechanisms. Transport studies with [14C]ADR, performed in the presence and absence of chemosensitizers, confirmed the good correlation of P-glycoprotein function with the pattern of resistance found in proliferation assays. Cellular accumulation of [3H]cyclosporin was reduced to 71% of that of the F4-6 controls in F4-6RADR-CsA cells, but remained at the level of controls in F4-6RADR cells. Results indicate that increased amounts of the P-glycoprotein--besides other, perhaps more important mechanisms that are as yet unknown--partially mediate CsA resistance in F4-6RADR-CsA cells. We have designated this new form of resistance "secondary combined resistance" (SCR). The results suggest that at least some clinical cases of insensitivity to chemosensitizers or of relapse after reversing therapy could be explained by SCR, and that resensitizing treatment of tumor patients should be based on the consideration of several chemosensitizers of different pharmacodynamics. PMID:7907333

Dietel, M; Herzig, I; Reymann, A; Brandt, I; Schaefer, B; Bunge, A; Heidebrecht, H J; Seidel, A

1994-01-01

197

Redox Regulation of Multidrug Resistance in Cancer Chemotherapy: Molecular Mechanisms and Therapeutic Opportunities  

OpenAIRE

The development of multidrug resistance to cancer chemotherapy is a major obstacle to the effective treatment of human malignancies. It has been established that membrane proteins, notably multidrug resistance (MDR), multidrug resistance protein (MRP), and breast cancer resistance protein (BCRP) of the ATP binding cassette (ABC) transporter family encoding efflux pumps, play important roles in the development of multidrug resistance. Overexpression of these transporters has been observed freq...

Kuo, Macus Tien

2009-01-01

198

Multidrug-Resistant Staphylococcus aureus in US Meat and Poultry  

OpenAIRE

We characterized the prevalence, antibiotic susceptibility profiles, and genotypes of Staphylococcus aureus among US meat and poultry samples (n = 136). S. aureus contaminated 47% of samples, and multidrug resistance was common among isolates (52%). S. aureus genotypes and resistance profiles differed significantly among sample types, suggesting food animal–specific contamination.

Waters, Andrew E.; Contente-cuomo, Tania; Buchhagen, Jordan; Liu, Cindy M.; Watson, Lindsey; Pearce, Kimberly; Foster, Jeffrey T.; Bowers, Jolene; Driebe, Elizabeth M.; Engelthaler, David M.; Keim, Paul S.; Price, Lance B.

2011-01-01

199

Interaction of 11C-Tariquidar and 11C-Elacridar with P-glycoprotein and Breast Cancer Resistance Protein at the Human Blood-Brain Barrier  

Science.gov (United States)

The adenosine triphosphate-binding cassette transporters P-glycoprotein (Pgp) and breast cancer resistance protein (BCRP) are 2 major gatekeepers at the blood-brain barrier (BBB) which restrict brain distribution of several clinically used drugs. In this study we investigated the suitability of the radiolabeled Pgp/BCRP inhibitors 11C-tariquidar and 11C-elacridar to assess Pgp density in human brain with PET. Methods Healthy subjects underwent a first PET scan of 120 min duration with either 11C-tariquidar (n = 6) or 11C-elacridar (n = 5) followed by a second PET scan of 60 min duration with (R)-11C-verapamil. During scan 1 (at 60 min after radiotracer injection) unlabeled tariquidar (3 mg/kg) was intravenously administered. Data was analyzed using 1-tissue 2-rate-constant (1T2K) and 2-tissue 4-rate-constant (2T4K) compartment models using either metabolite-corrected or uncorrected arterial input functions. Results Following injection of 11C-tariquidar or 11C-elacridar, brain PET signal corrected for radioactivity in vasculature was very low (~0.1 standardized uptake value) with slow washout. In response to tariquidar injection, a moderate, but statistically significant rise in brain PET signal was observed for 11C-tariquidar (+27 ± 15%, P = 0.014, paired t-test) and 11C-elacridar (+21 ± 15%, P = 0.014) without changes in plasma activity concentrations. Low levels of radiolabeled metabolites (<25%) were detected in plasma at time points up to 60 min after injection of 11C-tariquidar or 11C-elacridar. The 2T4K model provided better data fits than the 1T2K model. Model outcome parameters were similar when metabolite-corrected or uncorrected input functions were used. There was no significant correlation between distribution volumes (VT) of 11C-tariquidar or 11C-elacridar and VTs of (R)-11C-verapamil in different brain regions. Conclusion The in vivo behavior of 11C-tariquidar and 11C-elacridar was consistent with that of dual Pgp/BCRP substrates. Both tracers were unable to visualize cerebral Pgp density, which was most likely related to insufficiently high binding affinities in relation to the very low density of Pgp in human brain (~1.3 nM). Despite their inability to visualize Pgp density, 11C-tariquidar and 11C-elacridar may find use as a new class of radiotracers to study the interplay of Pgp and BCRP at the human BBB in limiting brain uptake of dual substrates. PMID:23833270

Bauer, Martin; Karch, Rudolf; Zeitlinger, Markus; Stanek, Johann; Philippe, Cécile; Wadsak, Wolfgang; Mitterhauser, Markus; Jäger, Walter; Haslacher, Helmuth; Müller, Markus; Langer, Oliver

2013-01-01

200

Mechanisms of tetrandrine and 5-bromotetrandrine in reversing multidrug resistance may relate to down-regulation of multidrug resistance associated protein 7 expression.  

Science.gov (United States)

Both tetrandrine (Tet) and 5-bromotetrandrine (BrTet) can effectively reverse P-glycoprotein (P-gp)-mediated multidrug resistance (MDR). The structure of multidrug resistance associated protein 7 (MRP7) has its own specificity and difference compared with other members of the MRP family. This study was aimed to investigate whether Tet and BrTet can inhibit the expression level of MRP7 so as to further look into the mechanisms of the reversal effects of Tet and BrTet on MDR. The inhibitory effects of daunorubicin (DNR) used alone on the proliferation of K562 and K562/A02 cells were evaluated by MTT assay, the IC(50) of DNR and drug resistant folds were calculated. The mRNA level of MRP7 was tested by real-time PCR, and the protein levels of MRP7 and P-gp were tested by Western blot. The DNR accumulation was analyzed by flow cytometry (FCM). The results showed that the resistance of K562/A02 cells to DNR was 23.65-folds of that of K562 cells. After administration of 1 µmol/L Tet or 2 µmol/L BrTet, the mRNA level of MRP7 in the K562/A02 cells decreased to 2% and 12% respectively, and the protein level of MRP7 decreased by 53.2% and 83.7% respectively. The protein level of P-gp decreased by 58.47% and 52.20% in the 1 µmol/L Tet and 2 µmol/L BrTet groups. FCM detection showed that 1 µmol/L Tet and 2 µmol/L BrTet significantly increased the accumulation of DNR in K562/A02 cells by 94.32% and 271% respectively. It is concluded that Tet and BrTet both can reverse MDR in vitro. The mechanisms may be related to the inhibition of MRP7 overexpression and the increase of anticancer drug concentration in cells. At the same molar concentration, the effects of Tet and BrTet in inhibiting the protein level of MRP7 expression do not show significant difference. PMID:22739155

Cheng, Jian; Dai, Jing-Ying; Chen, Bao-An; Cai, Xiao-Hui; Wang, Shuai; Gao, Feng

2012-06-01

201

Investigation of the role of LRP in multidrug resistance  

OpenAIRE

There have been many reports linking the overexpression of the lung resistance-related protein (LRP) with cross-resistance to chemotherapeutic drugs. However, no conclusive evidence existed to link LRP with a direct role in multidrug resistance (LRP). The OAW42SR is a cell line derived from a serous adenocarcinoma of the ovaries, and displays an increase in resistance to cytotoxic drugs concomitant with a moderate increase in LRP expression. Anti- LRP ribozyme and antisense expression plasmid...

Byrne, Daragh

1998-01-01

202

Artemisinin induces doxorubicin resistance in human colon cancer cells via calcium-dependent activation of HIF-1alpha and P-glycoprotein overexpression  

OpenAIRE

BACKGROUND AND PURPOSE: Artemisinin is an antimalarial drug exerting pleiotropic effects, such as the inhibition of the transcription factor nuclear factor-kappa B and of the sarcoplasmic/endoplasmic reticulum Ca(++)-ATPase (SERCA) of P. falciparum. As the sesquiterpene lactone thapsigargin, a known inhibitor of mammalian SERCA, enhances the expression of P-glycoprotein (Pgp) by increasing the intracellular Ca(++) ([Ca(++)](i)) level, we investigated whether artemisinin and its structural hom...

Bosia, Amalia; Pescarmona, Gianpiero; Ghigo, Dario Antonio; Miraglia, Erica; Doublier, Sophie; Riganti, Chiara

2009-01-01

203

Coencapsulated doxorubicin and bromotetrandrine lipid nanoemulsions in reversing multidrug resistance in breast cancer in vitro and in vivo.  

Science.gov (United States)

Multidrug resistance has remained a major cause of treatment failure in chemotherapy due to the presence of P-glycoproteins (P-gp) that actively pump drugs from inside the cell to the outside. P-gp inhibitors were developed and coadministered with chemotherapeutic drugs to overcome the effect of efflux pumps thus enhancing the chemosensitivity of therapeutics. Our study aimed at developing a lipid nanoemulsion system for the coencapsulation of doxorubicin (DOX) and bromotetrandrine (W198) to reverse multidrug resistance (MDR) in breast cancer. W198 was a potent P-gp inhibitor, and DOX was selected as a model compound which is a common substrate for P-gp. Coencapsulated DOX and W198 lipid nanoemulsions (DOX/W198-LNs) displayed significantly enhanced cytotoxicity in DOX-resistant human breast cancer cells (MCF-7/ADR) compared with DOX loaded lipid nanoemulsions (DOX-LNs) (p < 0.05), which is due to the enhanced intracellular uptake of DOX in MCF-7/ADR cells. The biodistribution study was performed using a nude mice xenograft model, which demonstrates enhanced tumor uptake of DOX in the DOX/W198-LN treated group. Compared with DOX solution, DOX/W198-LNs showed reduced cardiac toxicity and gastrointestinal injury in rats. Taken together, DOX/W198-LNs represent a promising formulation for overcoming MDR in breast cancer. PMID:25469833

Cao, Xi; Luo, Jingwen; Gong, Tao; Zhang, Zhi-Rong; Sun, Xun; Fu, Yao

2015-01-01

204

The role of transport processes in survival of lactic acid bacteria. Energy transduction and multidrug resistance.  

Science.gov (United States)

Lactic acid bacteria play an essential role in many food fermentation processes. They are anaerobic organisms which obtain their metabolic energy by substrate phosphorylation. In addition three secondary energy transducing processes can contribute to the generation of a proton motive force: proton/substrate symport as in lactic acid excretion, electrogenic precursor/product exchange as in malolactic and citrolactic fermentation and histidine/histamine exchange, and electrogenic uniport as in malate and citrate uptake in Leuconostoc oenos. In several of these processes additional H+ consumption occurs during metabolism leading to the generation of a pH gradient, internally alkaline. Lactic acid bacteria have also developed multidrug resistance systems. In Lactococcus lactis three toxin excretion systems have been characterized: cationic toxins can be excreted by a toxin/proton antiport system and by an ABC-transporter. This cationic ABC-transporter has surprisingly high structural and functional analogy with the human MDR1-(P-glycoprotein). For anions an ATP-driven ABC-like excretion systems exist. PMID:9049023

Konings, W N; Lolkema, J S; Bolhuis, H; van Veen, H W; Poolman, B; Driessen, A J

1997-02-01

205

Multidrug Resistant Mycobacterium leprae from Patients with Leprosy  

OpenAIRE

Sequences of the folP1, rpoB, and gyrA genes were analyzed for 88 isolates of Mycobacterium leprae from leprosy patients in Japan, Haiti, Indonesia, Pakistan, and the Philippines. Thirteen isolates (14.8%) showed representative mutations in more than two genes, suggesting the emergence of multidrug-resistant M. leprae.

Maeda, Shinji; Matsuoka, Masanori; Nakata, Noboru; Kai, Masanori; Maeda, Yumi; Hashimoto, Ken; Kimura, Hiroaki; Kobayashi, Kazuo; Kashiwabara, Yoshiko

2001-01-01

206

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

Science.gov (United States)

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 extrusion pumps, could readily be available for clinical translation in the battle against resistant tumors. PMID:25173796

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

2014-11-28

207

Beneficial effect of tetrandrine on refractory epilepsy via suppressing P-glycoprotein.  

Science.gov (United States)

Patients with refractory epilepsy are resistance to antiepileptic drugs (AEDs). The mechanisms of drug resistance are varied, but one of them is the overexpression of multidrug transporters, such as P-glycoprotein (P-gp), in the brain. Tetrandrine (TTD) is a bis-benzylisoquinoline alkaloid isolated from the root of Stephania tetrandra (S, Moore) and is found to have a favorable effect against multidrug resistance (MDR) in chemotherapy. However, whether TTD affects AEDs in refractory epilepsy is unknown. In this study, we investigated the change in AED treatment efficacy in doxorubicin-induced drug resistant cells after TTD administration. We also examined the effect of TTD on seizure behaviors in the refractory epileptic rats, specifically the expression of MDR1 mRNA and P-gp protein in the cortex and hippocampus of the refractory epileptic rats. Our results demonstrated that TTD decreased cell resistance to phenytoin and valproate. TTD decreased seizure rate and increased the treatment efficacy of AEDs by reducing the expression of P-gp at mRNA and protein levels in vivo. These data support the use of TTD as an adjuvant drug for treating refractory epilepsy. PMID:25233150

Chen, Yinghui; Xiao, Xia; Wang, Cuicui; Jiang, Huiyuan; Hong, Zhen; Xu, Guoxiong

2014-10-22

208

Multidrug-Resistant Enterococci Lack CRISPR-cas  

OpenAIRE

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...

Palmer, Kelli L.; Gilmore, Michael S.

2010-01-01

209

Molecular fingerprinting of multidrug-resistant Salmonella enterica serotype Typhi.  

OpenAIRE

For epidemiologic investigations, the primary subdivision of Salmonella Typhi is vi-phage typing; 106 Vi-phage types are defined. For multidrug-resistant strains the most common types have been M1 (Pakistan) and E1 (India, Pakistan, Bangladesh, and the Arabian Gulf); a strain untypable with the Vi phages has been responsible for a major epidemic in Tajikistan. Most often, isolates from the Indian subcontinent have been resistant to ampicillin, chloramphenicol, streptomycin, sulfonamides, tetr...

Hampton, M. D.; Ward, L. R.; Rowe, B.; Threlfall, E. J.

1998-01-01

210

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

Science.gov (United States)

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 these transporters. Genistein (GNT) is a phytoestrogen abundant in soybean that exerts its genomic effects through Estrogen-Receptors and Pregnane-X-Receptor (PXR), which are involved in the regulation of the above-mentioned transporters. We evaluated the effect of GNT on the expression and activity of P-gp, MRP2, MRP3 and BCRP in HCC-derived HepG2 cells. GNT (at 1.0 and 10 ?M) increased P-gp and MRP2 protein expression and activity, correlating well with an increased resistance to sorafenib cytotoxicity as detected by the methylthiazole tetrazolium (MTT) assay. GNT induced P-gp and MRP2 mRNA expression at 10 but not at 1.0 ?M concentration suggesting a different pattern of regulation depending on the concentration. Induction of both transporters by 1.0 ?M GNT was prevented by cycloheximide, suggesting translational regulation. Downregulation of expression of the miR-379 by GNT could be associated with translational regulation of MRP2. Silencing of PXR abolished P-gp induction by GNT (at 1.0 and 10 ?M) and MRP2 induction by GNT (only at 10 ?M), suggesting partial mediation of GNT effects by PXR. Taken together, the data suggest the possibility of nutrient-drug interactions leading to enhanced chemoresistance in HCC when GNT is ingested with soy rich diets or dietary supplements. PMID:25781341

Rigalli, Juan Pablo; Ciriaci, Nadia; Arias, Agostina; Ceballos, María Paula; Villanueva, Silvina Stella Maris; Luquita, Marcelo Gabriel; Mottino, Aldo Domingo; Ghanem, Carolina Inés; Catania, Viviana Alicia; Ruiz, María Laura

2015-01-01

211

Regulation of multidrug resistance proteins by genistein in a hepatocarcinoma cell line: impact on sorafenib cytotoxicity.  

Science.gov (United States)

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 these transporters. Genistein (GNT) is a phytoestrogen abundant in soybean that exerts its genomic effects through Estrogen-Receptors and Pregnane-X-Receptor (PXR), which are involved in the regulation of the above-mentioned transporters. We evaluated the effect of GNT on the expression and activity of P-gp, MRP2, MRP3 and BCRP in HCC-derived HepG2 cells. GNT (at 1.0 and 10 ?M) increased P-gp and MRP2 protein expression and activity, correlating well with an increased resistance to sorafenib cytotoxicity as detected by the methylthiazole tetrazolium (MTT) assay. GNT induced P-gp and MRP2 mRNA expression at 10 but not at 1.0 ?M concentration suggesting a different pattern of regulation depending on the concentration. Induction of both transporters by 1.0 ?M GNT was prevented by cycloheximide, suggesting translational regulation. Downregulation of expression of the miR-379 by GNT could be associated with translational regulation of MRP2. Silencing of PXR abolished P-gp induction by GNT (at 1.0 and 10 ?M) and MRP2 induction by GNT (only at 10 ?M), suggesting partial mediation of GNT effects by PXR. Taken together, the data suggest the possibility of nutrient-drug interactions leading to enhanced chemoresistance in HCC when GNT is ingested with soy rich diets or dietary supplements. PMID:25781341

Rigalli, Juan Pablo; Ciriaci, Nadia; Arias, Agostina; Ceballos, María Paula; Villanueva, Silvina Stella Maris; Luquita, Marcelo Gabriel; Mottino, Aldo Domingo; Ghanem, Carolina Inés; Catania, Viviana Alicia; Ruiz, María Laura

2015-01-01

212

[Investigation of extensive drug resistance in multidrug resistance tuberculosis isolates].  

Science.gov (United States)

Increasing number of drug resistant tuberculosis (TB) cases, observed in recent years, is an important public health problem. Extensively drug resistant TB (XDR-TB) is the development of resistance against any fluoroquinolones and at least one of the injectable second line anti-TB drugs in addition to resistance against isoniazide and rifampicin which are the first line anti-TB drugs [definition of multidrug resistant TB (MDR-TB)]. Anti-TB therapy failed with first-line anti-TB drugs due to MDR-TB cases is being planned according to second-line anti-TB drug susceptibility test results if available and if not, standart treatment protocols are used. Although it is recommended that individual anti-TB therapy should be designed according to the isolate's susceptibility test results, standart therapeutic protocols are always needed since second-line anti-TB drug susceptibility testing generally could not be performed in developing countries like Turkey. For this reason, nationwide and regional surveillance studies to determine the resistance patterns are always needed to make decisions about the standard therapy algorithms. In this study, it was aimed to investigate the presence of extensive drug resistance among 81 MDR-TB isolates obtained from various health care facilities from Istanbul, Izmir and Manisa and to determine the XDR-TB incidence in Marmara and Aegean regions. Furthermore, we aimed to provide epidemiological data to clinicians to support their choice of second-line anti-TB drugs for MDR-TB infections. Susceptibility testing of isolates for the first and the second-line anti-TB drugs were performed by using modified Middlebrook 7H9 broth in fluorometric BACTEC MGIT 960 system (Becton Dickinson, USA). Eighty-one MDR-TB isolates included in this study were isolated from 43 (53.1%) patients residing in Istanbul, 26 (32.1%) in Izmir and 12 (14.8%) in Manisa provinces. We could not find any isolate consistent with XDR-TB definition in this study. Second-line drug resistance rates of MDR-TB isolates to amikacin and kanamycin were 1.2%, ofloxacin and levofloxacin were 2.5%, capreomycin was 14.8%, ethionamide was 37% whereas linezolid resistance was not detected. Statistically significant correlation was detected between resistance rates of these antibiotic pairs; levofloxacin-ofloxacin (p< 0.01), amikacin-kanamycin (p= 0.01) and streptomycin-ethionamide (p= 0.04). In our study, extensive drug resistance was not encountered in any MDR-TB isolates while high resistance rates was observed against ethionamide and capreomycin. It can be concluded that parenteral aminoglycosides amikasin and kanamycin, fluoroquinolones and linezolid seemed to be reliable anti-TB agents in MDR-TB treatment, however, further larger scale studies are needed. PMID:23390903

Bektöre, Bayhan; Haznedaro?lu, Tunçer; Baylan, Orhan; Ozyurt, Mustafa; Ozkütük, Nuri; Satana, Dilek; Cavu?o?lu, Cengiz; Seber, Engin

2013-01-01

213

Pharmacogenomic and molecular docking studies on the cytotoxicity of the natural steroid wortmannin against multidrug-resistant tumor cells.  

Science.gov (United States)

Wortmannin is a cytotoxic compound derived from the endophytic fungi Fusarium oxysporum, Penicillium wortmannii and Penicillium funiculosum that occurs in many plants, including medicinal herbs. The rationale to develop novel anticancer drugs is the frequent development of tumor resistance to the existing antineoplasic agents. Therefore, it is mandatory to analyze resistance mechanisms of novel drug candidates such as wortmannin as well to bring effective drugs into the clinic that have the potential to bypass or overcome resistance to established drugs and to substantially increase life span of cancer patients. In the present project, we found that P-glycoprotein-overexpressing tumor cells displaying the classical multidrug resistance phenotype toward standard anticancer drugs were not cross-resistant to wortmannin. Furthermore, three point-mutated PIK3CA protein structures revealed similar binding energies to wortmannin than wild-type PIK3CA. This protein is the primary target of wortmannin and part of the PI3K/AKT/mTOR signaling pathway. PIK3CA mutations are known to be associated with worse response to therapy and shortened its activity toward wild-type and mutant PIK3CA with similar efficacy. PMID:25636880

Kuete, Victor; Saeed, Mohamed E M; Kadioglu, Onat; Börtzler, Jonas; Khalid, Hassan; Greten, Henry Johannes; Efferth, Thomas

2015-01-15

214

Mass spectrometry reveals synergistic effects of nucleotides, lipids, and drugs binding to a multidrug resistance efflux pump  

Science.gov (United States)

Multidrug resistance is a serious barrier to successful treatment of many human diseases, including cancer, wherein chemotherapeutics are exported from target cells by membrane-embedded pumps. The most prevalent of these pumps, the ATP-Binding Cassette transporter P-glycoprotein (P-gp), consists of two homologous halves each comprising one nucleotide-binding domain and six transmembrane helices. The transmembrane region encapsulates a hydrophobic cavity, accessed by portals in the membrane, that binds cytotoxic compounds as well as lipids and peptides. Here we use mass spectrometry (MS) to probe the intact P-gp small molecule-bound complex in a detergent micelle. Activation in the gas phase leads to formation of ions, largely devoid of detergent, yet retaining drug molecules as well as charged or zwitterionic lipids. Measuring the rates of lipid binding and calculating apparent KD values shows that up to six negatively charged diacylglycerides bind more favorably than zwitterionic lipids. Similar experiments confirm binding of cardiolipins and show that prior binding of the immunosuppressant and antifungal antibiotic cyclosporin A enhances subsequent binding of cardiolipin. Ion mobility MS reveals that P-gp exists in an equilibrium between different states, readily interconverted by ligand binding. Overall these MS results show how concerted small molecule binding leads to synergistic effects on binding affinities and conformations of a multidrug efflux pump. PMID:23690617

Marcoux, Julien; Wang, Sheila C.; Politis, Argyris; Reading, Eamonn; Ma, Jerome; Biggin, Philip C.; Zhou, Min; Tao, Houchao; Zhang, Qinghai; Chang, Geoffrey; Morgner, Nina; Robinson, Carol V.

2013-01-01

215

Effect of methylglyoxal on multidrug-resistant Pseudomonas aeruginosa  

Directory of Open Access Journals (Sweden)

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.

KunihikoNishino

2014-04-01

216

Effect of methylglyoxal on multidrug-resistant Pseudomonas aeruginosa.  

Science.gov (United States)

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 ?g/ml (1.7-7.1 mM) and is not recognized by drug efflux systems. PMID:24860556

Hayashi, Katsuhiko; Fukushima, Aiko; Hayashi-Nishino, Mitsuko; Nishino, Kunihiko

2014-01-01

217

Expression of the neural cell adhesion molecule CD56 is not associated with P-glycoprotein overexpression in core-binding factor acute myeloid leukemia.  

Science.gov (United States)

Acute myeloid leukemia (AML) with rearrangement of the core-binding factor (CBF) alpha or beta subunit gene has a favorable prognosis, but CD56 expression in CBFalpha-AML is associated with short disease-free survival. A proposed mechanism is overexpression of the multidrug resistance (MDR) protein P-glycoprotein (Pgp). CD56 expression, Pgp expression and function, and expression of the additional MDR proteins multidrug resistance protein-1 (MRP-1), lung resistance protein (LRP) and breast cancer resistance protein (BCRP) were studied in pretreatment blasts from 25 CBF-AML patients. CD56 expression was frequent in CBFalpha but rare in CBFbeta, and Pgp expression and function were frequent in both subtypes. CD56 expression did not correlate with Pgp expression or function, nor with expression of the other MDR proteins. Treatment failure associated with CD56 expression in CBFalpha-AML is not likely attributable to Pgp. PMID:15068897

Suvannasankha, Attaya; Minderman, Hans; O'Loughlin, Kieran L; Sait, Sheila N J; Stewart, Carleton C; Greco, William R; Baer, Maria R

2004-05-01

218

Multidrug-Resistant Tuberculosis (MDR TB)  

Science.gov (United States)

... TB disease. What is extensively drug resistant tuberculosis (XDR TB)? Extensively drug resistant TB (XDR TB) is a rare type of MDR TB ... drugs (i.e., amikacin, kanamycin, or capreomycin). Because XDR TB is resistant to the most potent TB ...

219

Identification of the multidrug resistance-associated protein (mrp) related gene in red mullet (Mullus barbatus).  

Science.gov (United States)

Multixenobiotic resistance mechanism (MXR) in aquatic organisms is mediated by the activity of the P-glycoprotein (Pgp) transporter that binds and actively effluxes different chemicals out of cell. In addition to the Pgp, several other, non-Pgp transport proteins have been recently identified in different human and animal tissues. Given their characteristics and tissue distribution we hypothesized that members of the so-called multidrug resistance-associated protein (MRP) family may be expressed in aquatic organisms. This study attempted to identify MRP related genes in different tissues of several marine and freshwater bivalves (Mytilus galloprovincialis, Dreissena polymorpha, Anodonta cygnea) and fish species (Mullus barbatus, Cyprinus carpio, Salmo trutta). Following an alignment of known MRP1 and MRP2 human sequences, as well as the GenBank available mrp2 sequences from different animals, we determined highly conserved regions and used them to design three pairs of consensus primers. Total RNA was isolated, reverse transcribed to cDNA and the obtained cDNAs were PCR amplified with the corresponding primers. The amplified PCR products were sequenced and their homology compared with Pgp and MRP protein sequences from different species. The expression of MRP related mRNA was clearly identified only in liver tissue isolated from red mullet, with homologies at the protein level ranging from 75% to 76%. Described results clearly pointed at the possibility that at least in the red mullet MXR as a general defense mechanism may be mediated by the activities of at least two different types of transport proteins. PMID:15178032

Sauerborn, Roberta; Polancec, Darija Stupin; Zaja, Roko; Smital, Tvrtko

2004-01-01

220

Defective autophagy in multidrug resistant cells may lead to growth inhibition by BH3-mimetic gossypol.  

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The clinical efficacy of many chemotherapeutic agents has been reduced due to the development of drug resistance. In this article, we aimed to validate gossypol, a natural BH3 mimetic found in cottonseeds, as a potential therapeutic to overcome multidrug resistance (MDR). Gossypol was found to retain its efficacy in v-Ha-ras-transformed NIH 3T3 cells that overexpressed P-glycoprotein (Ras-NIH 3T3/Mdr), which was similar to the efficacy observed in their parental counterparts (Ras-NIH 3T3). A rhodamine assay revealed that the alteration of MDR activity did not contribute to the cytotoxic effect of gossypol. Gossypol caused a G2 /M arrest by the induction of p21(Cip1) and the down-regulation of p27(Kip1) expression in Ras-NIH 3T3 cells, whereas no significant G2 /M arrest was exhibited in Ras-NIH 3T3/Mdr cells. Surprisingly, a 48-h treatment with gossypol induced apoptotic cell death in Ras-NIH 3T3 cells; however, gossypol induced both apoptosis and necrosis in Ras-NIH 3T3/Mdr cells, as determined with flow cytometry analysis. More notably, gossypol preferentially induced autophagy in Ras-NIH 3T3 cells but not in Ras-NIH 3T3/Mdr cells. Coimmunoprecipitation and flow cytometric analysis revealed that gossypol-induced autophagy is independent of the dissociation of Beclin 1 from Bcl-2 in Ras-NIH 3T3 cells. Taken together, these results suggest that the antiproliferative activity of gossypol appears to be due to cell-cycle arrest at the G2 /M phase, with the induction of apoptosis in Ras-NIH 3T3 cells. In addition, defective autophagy might contribute to apoptotic and necrotic cell death in response to gossypol in Ras-NIH 3T3/Mdr cells. PMID:23254564

Ahn, Jun-Ho; Jang, Gun-Hee; Lee, Michael

2013-07-01

221

Modification of sialylation is associated with multidrug resistance in human acute myeloid leukemia.  

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Aberrant cell surface sialylation patterns have been shown to correlate with tumor progression and metastasis. However, the role of sialylation regulation of cancer multidrug resistance (MDR) remains poorly understood. This study investigated sialylation in modification on MDR in acute myeloid leukemia (AML). Using mass spectrometry (MS) analysis, the composition profiling of sialylated N-glycans differed in three pairs of AML cell lines. Real-time PCR showed the differential expressional profiles of 20 sialyltransferase (ST) genes in the both AML cell lines and bone marrow mononuclear cells (BMMCs) of AML patients. The expression levels of ST3GAL5 and ST8SIA4 were detected, which were overexpressed in HL60 and HL60/adriamycin-resistant (ADR) cells. The altered levels of ST3GAL5 and ST8SIA4 were found in close association with the MDR phenotype changing of HL60 and HL60/ADR cells both in vitro and in vivo. Further data demonstrated that manipulation of these two genes' expression modulated the activity of phosphoinositide-3 kinase (PI3K)/Akt signaling pathway and its downstream target thus regulated the proportionally mutative expression of P-glycoprotein (P-gp) and MDR-related protein 1 (MRP1), both of which are known to be involved in MDR. Blocking the PI3K/Akt pathway by its specific inhibitor LY294002 or by Akt small interfering RNA resulted in the reduced chemosensitivity of HL60/ADR cells. Therefore, this study indicated that sialylation involved in the development of MDR of AML cells probably through ST3GAL5 or ST8SIA4 regulating the activity of PI3K/Akt signaling and the expression of P-gp and MRP1. PMID:24531716

Ma, H; Zhou, H; Song, X; Shi, S; Zhang, J; Jia, L

2015-02-01

222

Enhanced effect of pH-sensitive mixed copolymer micelles for overcoming multidrug resistance of doxorubicin.  

Science.gov (United States)

P-glycoprotein (P-gp) mediated drug efflux has been recognized as a key factor contributing to the multidrug resistance (MDR) in tumor cells. To address this issue, a new pH-sensitive mixed copolymer micelles system composed of hyaluronic acid-g-poly(l-histidine) (HA-PHis) and d-?-tocopheryl polyethylene glycol 2000 (TPGS2k) copolymers was developed to co-deliver doxorubicin (DOX) and TPGS2k into drug-resistant breast cancer MCF-7 cells (MCF-7/ADR). The DOX-loaded HA-PHis/TPGS2k mixed micelles (HPHM/TPGS2k) were characterized to have a unimodal size distribution, high DOX loading content and a pH dependent drug release profile due to the protonation of poly(l-histidine). As compared to HA-PHis micelles (HPHM), the HPHM/TPGS2k showed higher and comparable cytotoxicity against MCF-7/ADR cells and MCF-7 cells, respectively. The enhanced MDR reversal effect was attributed to the higher amount of cellular uptake of HPHM/TPGS2k in MCF-7/ADR cells than HPHM, arising from the inhibition of P-gp mediated drug efflux by TPGS2k. The measurements of P-gp expression level and mitochondrial membrane potential indicate that the blank HPHM/TPGS2k inhibited P-gp activity by reducing mitochondrial membrane potential and depletion of ATP but without inhibition of P-gp expression. In vivo study of micelles in tumor-bearing mice indicate that HPHM/TPGS2k could reach the tumor site more effectively than HPHM. The pH-sensitive mixed micelles system has been demonstrated to be a promising approach for overcoming the MDR. PMID:25201738

Qiu, Lipeng; Qiao, Mingxi; Chen, Qing; Tian, Chenmin; Long, Miaomiao; Wang, Mingyue; Li, Zhen; Hu, Wen; Li, Gang; Cheng, Liang; Cheng, Lifang; Hu, Haiyang; Zhao, Xiuli; Chen, Dawei

2014-12-01

223

Lymphokine-activated killer cell susceptibility and adhesion molecule expression of multidrug resistant breast carcinoma  

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Full Text Available Abstract Reports showing susceptibility of multidrug resistant (MDR cancer cells to immune effectors, together with P-glycoprotein (P-gp expression in immune effector subsets, including immature natural killer (NK cells, and some activated T cells, suggest P-gp or some changes associated with it, have implications in immune-mediated mechanisms. A series of experiments were done to determine the nature of alterations associated with susceptibility to immune effector cells of MDR tumor cells. A cell line isolated from the malignant pleural effusion of a breast cancer patient was transfected with human and murine MDR1 genes, and four variants with different levels of MDR were obtained. Lymphokine-activated killer (LAK activity was measured by a 51Chromium release, and conjugate formation assays. MDR1 transfectant P-gp+ breast carcinoma lines had increased LAK susceptibility compared to their parent line. Some part of the increased LAK susceptibility of drug-resistant cell lines was at the binding/recognition level as shown by conjugate formation assays. This suggests that differences may exist between paired cell lines with respect to the expression of cell adhesion molecules (CAMs. Monoclonal antibodies (mAbs to CAMs and flow cytometry were used to quantitate these antigens. The CAMs studied were those previously found to be upregulated by stimulating NK cells with (interleukin-2 IL-2; ICAM-1 (CD54, LFA-3 (CD58, N-CAM (CD56, and the ? chain of LFA-1 (CD18. Although no differences in these CAMs were found between the breast carcinoma line and its MDR1-transfected variants, the target susceptibility results given above suggest that IL-2 treatment could be effective in combination with current protocols using chemotherapeutics, monoclonal antibodies (mAbs and stem cell transplantation.

Kerr Pauline E

2006-11-01

224

Effect of prostaglandin E2 on multidrug resistance transporters in human placental cells.  

Science.gov (United States)

Prostaglandin (PG) E2, a major product of cyclooxygenase (COX)-2, acts as an immunomodulator at the maternal-fetal interface during pregnancy. It exerts biologic function through interaction with E-prostanoid (EP) receptors localized to the placenta. The activation of the COX-2/PGE2/EP signal pathway can alter the expression of the ATP-binding cassette (ABC) transporters, multidrug resistance protein 1 [P-glycoprotein (Pgp); gene: ABCB1], and breast cancer resistance protein (BCRP; gene: ABCG2), which function to extrude drugs and xenobiotics from cells. In the placenta, PGE2-mediated changes in ABC transporter expression could impact fetal drug exposure. Furthermore, understanding the signaling cascades involved could lead to strategies for the control of Pgp and BCRP expression levels. We sought to determine the impact of PGE2 signaling mechanisms on Pgp and BCRP in human placental cells. The treatment of placental cells with PGE2 up-regulated BCRP expression and resulted in decreased cellular accumulation of the fluorescent substrate Hoechst 33342. Inhibiting the EP1 and EP3 receptors with specific antagonists attenuated the increase in BCRP. EP receptor signaling results in activation of transcription factors, which can affect BCRP expression. Although PGE2 decreased nuclear factor ?-light chain-enhancer of activated B activation and increased activator protein 1, chemical inhibition of these inflammatory transcription factors did not blunt BCRP up-regulation by PGE2. Though PGE2 decreased Pgp mRNA, Pgp expression and function were not significantly altered. Overall, these findings suggest a possible role for PGE2 in the up-regulation of placental BCRP expression via EP1 and EP3 receptor signaling cascades. PMID:25261564

Mason, Clifford W; Lee, Gene T; Dong, Yafeng; Zhou, Helen; He, Lily; Weiner, Carl P

2014-12-01

225

Germacrone reverses Adriamycin resistance through cell apoptosis in multidrug-resistant breast cancer cells  

OpenAIRE

Multidrug resistance (MDR) is a major obstacle to the chemotherapeutic treatment of breast cancer. Germacrone, the main component of Rhizoma Curcuma, has been shown to possess antitumor, anti-inflammatory and immunomodulatory properties. The aim of the present study was to investigate the effect of germacrone on MCF-7/Adriamycin (ADR) multidrug-resistant human breast cancer cells. The treatment of MCF-7/ADR cells with a combination of germacrone and ADR resulted in an increase in cytotoxicity...

Xie, Xiao-hong; Zhao, Hong; Hu, Yuan-yuan; Gu, Xi-dong

2014-01-01

226

Chemosensitization of a multidrug-resistant Leishmania tropica line by new sesquiterpenes from Maytenus magellanica and Maytenus chubutensis.  

Science.gov (United States)

Parasite resistance to drugs has emerged as a major problem in current medicine, and therefore, there is great clinical interest in developing compounds that overcome these resistances. In an intensive study of South American medicinal plants, herein we report the isolation, structure elucidation, and biological activity of dihydro-beta-agarofuran sesquiterpenes from the roots of Maytenus magellanica (1-14) and M. chubutensis (14-17). This type of natural products may be considered as privileged structures. The structures of 10 new compounds, 1, 3, 6-9, and12-15, were determined by means of (1)H and (13)C NMR spectroscopic studies, including homonuclear (COSY and ROESY) and heteronuclear correlation experiments (HMQC and HMBC). The absolute configurations of eight hetero- and homochromophoric compounds, 1, 3,6-9, 12, and 13, were determined by means of CD studies. Fourteen compounds, 1-3 and 6-16, have been tested on a multidrug-resistant Leishmania tropica line overexpressing a P-glycoprotein-like transporter to determine their ability to revert the resistance phenotype and to modulate intracellular drug accumulation. From this series, 1, 2, 3, 14, and 15 showed potent activity, 1 being the most active compound. The structure-activity relationships of the different compounds are discussed. PMID:11741484

Kennedy, M L; Cortés-Selva, F; Pérez-Victoria, J M; Jiménez, I A; González, A G; Muñoz, O M; Gamarro, F; Castanys, S; Ravelo, A G

2001-12-20

227

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

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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.

Molento Marcelo B.

2001-01-01

228

Cinnamylidene ketones as potential modulators of multidrug resistance in mouse lymphoma and human colon cancer cell lines.  

Science.gov (United States)

The resistance to chemotherapy of cancer cells is mediated by the overexpression of P-glycoprotein, as an ATP-dependent membrane efflux pump. Two families of compounds have been screened, the cinnamylidenecycloalkanones and cinnamylidenebenzocycloalkanones, as promising multidrug resistance (MDR) reversal agents on mouse lymphoma and human colon cancer (COL0320) cell lines. The antiproliferative effects of the cinnamylidene derivatives were tested with the MTT method The MDR effect on drug accumulation was tested by flow cytometry. Combinations of resistance modifiers and cytostatics were tested on the two cell lines to obtain evidence for additive or synergistic interactions. Verapamil was applied as a resistance-modifying positive control. The best effects in the reversal of MDR in both cell lines were exhibited by the methoxy derivatives 2-(2-methaoxycinnamylidene)indan-1-one, 2-(2-methoxycinnamylidene)-3,4-dihydro-2H-naphthalen-1-one, 6-(2-methoxycinnamylidene)-6,7,8,9-tetrahydrocyclohepten-5-one), 2-cinnamylidene-3,4-dihydro-2H-naphthalen-1-one and 6-cinnamylidene-6,7,8,9-tetrahydrobenzocyclohepten-5-one. 2-(2-methoxycinnamylidene) indan-1-one and 2-(2-methoxy-cinnamylidene)-3,4-dihydro-2H-naphthalen-1-one were able to enhance the antiproliferative activity of doxorubicin in a synergistic way. PMID:16433039

Engi, Helga; Gyémánt, Nóra; Lóránd, Tamás; Lévai, Albert; Ocsovszki, Imre; Molnár, Joseph

2006-01-01

229

Paediatric Multidrug-Resistant Tuberculosis with HIV Coinfection: A Case Report  

OpenAIRE

Background. Tuberculosis is a major public health problem, and its control has been facing a lot of challenges with emergence of HIV. The occurrence of multidrug-resistant strain has also propounded the problem especially in children where diagnosis is difficult to make. Multidrug-resistant tuberculosis (MDR-TB) is in vitro resistant to isoniazid (H) and rifampicin (R). Paediatric multi-drug resistant tuberculosis with HIV coinfection is rare, and there is no documented report from Nigeria. O...

Nwokeukwu, Huldah I.; Okafor, Paulinus N.; Onuka Okorie; Ukpabi, Ihuoma K.

2013-01-01

230

Aedesin: structure and antimicrobial activity against multidrug resistant bacterial strains.  

Science.gov (United States)

Multidrug resistance, which is acquired by both Gram-positive and Gram-negative bacteria, causes infections that are associated with significant morbidity and mortality in many clinical settings around the world. Because of the rapidly increasing incidence of pathogens that have become resistant to all or nearly all available antibiotics, there is a need for a new generation of antimicrobials with a broad therapeutic range for specific applications against infections. Aedesin is a cecropin-like anti-microbial peptide that was recently isolated from dengue virus-infected salivary glands of the Aedes aegypti mosquito. In the present study, we have refined the analysis of its structural characteristics and have determined its antimicrobial effects against a large panel of multidrug resistant bacterial strains, directly isolated from infected patients. Based the results from nuclear magnetic resonance spectroscopy analysis, Aedesin has a helix-bend-helix structure typical for a member of the family of ?-helix anti-microbial peptides. Aedesin efficiently killed Gram-negative bacterial strains that display the most worrisome resistance mechanisms encountered in the clinic, including resistance to carbapenems, aminoglycosides, cephalosporins, 4th generation fluoroquinolones, folate inhibitors and monobactams. In contrast, Gram-positive strains were insensitive to the lytic effects of the peptide. The anti-bacterial activity of Aedesin was found to be salt-resistant, indicating that it is active under physiological conditions encountered in body fluids characterized by ionic salt concentrations. In conclusion, because of its strong lytic activity against multidrug resistant Gram-negative bacterial strains displaying all types of clinically relevant resistance mechanisms known today, Aedesin might be an interesting candidate for the development of alternative treatment for infections caused by these types of bacteria. PMID:25162372

Godreuil, Sylvain; Leban, Nadia; Padilla, André; Hamel, Rodolphe; Luplertlop, Natthanej; Chauffour, Aurélie; Vittecoq, Marion; Hoh, François; Thomas, Frédéric; Sougakoff, Wladimir; Lionne, Corinne; Yssel, Hans; Missé, Dorothée

2014-01-01

231

Multidrug-Resistant Tuberculosis (MDR TB)  

Science.gov (United States)

... the CDC reported that 9.2 percent of tuberculosis cases in the U.S. were resistant to isoniazid, the ... CDC also reported that 1.3 percent of tuberculosis cases in the U.S. were resistant to both isoniazid ...

232

[Multi-drug resistant bacteria and antibiotics].  

Science.gov (United States)

Antibiotics are still routinely prescribed, despite the increase in bacterial resistance to these drugs. To contain this public health problem, doctors need to be better trained and the general public better informed. PMID:23865247

Carlet, Jean

2013-01-01

233

[Multidrug resistance determinants in acute myeloid leukemia developed in persons exposed to ionizing radiation due to the Chernobyl accident].  

Science.gov (United States)

The results of multidrug resistance determinants expression analysis on leukemic cells of 56 acute myeloid leukemia (AML) patients by immunophenotyping are presented. Of these, there were 21 persons exposed to ionizing radiation due to the Chemobyl accident with radiation-associated AML and 35 patients with spontaneous leukemia. The aim of this study was to determine if transport proteins (P-glycoprotein, LRP, and MDR1), apoptosis-related proteins (Fas, Bcl-2, Bax, p53, and Bcl-X(L)), and topoisomerase IIalpha expression in AML patients with the history of radiation exposure differed from those in spontaneous AML cases. Leukemic cells in patients with radiation-associated diseases compared to spontaneous AML more often overexpressed antiapoptotic oncoprotein Bcl-2 (12/21 vs. 6/35, p overexpression significantly correlated with resistant disease in patients with radiation-associated AML (r = 0.47, p < 0.05), but was not a prognostic variable for the treatment outcome in terms of overall survival. Defects in pathways of drug-induced apoptosis and function of pump, that actively effluxes drugs could contribute significantly to developing drug resistance in radiation-associated AML. PMID:17133722

Klimenko, S V; Bazyka, D A; Maznichenko, O L; Goliarnik, N A; Il'enko, I N; Bebeshko, V G

2006-01-01

234

Glutamate-mediated upregulation of the multidrug resistance protein 2 in porcine and human brain capillaries.  

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As a member of the multidrug-resistance associated protein (MRP) family, MRP2 affects the brain entry of different endogenous and exogenous compounds. Considering the role of this transporter at the blood-brain barrier, the regulation is of particular interest. However, there is limited knowledge regarding the factors that regulate MRP2 in neurologic disease states. Thus, we addressed the hypothesis that MRP2 might be affected by a glutamate-induced signaling pathway that we previously identified as one key mechanism in the regulation of P-glycoprotein. Studies in isolated porcine brain capillaries confirmed that glutamate and N-methyl-d-aspartic acid (NMDA) exposure upregulates expression and function of MPR2. The involvement of the NMDA receptor was further suggested by the fact that the NMDA receptor antagonist MK-801 [(5S,10R)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine], as well as the NMDA receptor glycine binding site antagonist L-701,324 [7-chloro-4-hydroxy-3-(3-phenoxy)phenyl-2(1H)-quinolinone], prevented the impact of glutamate. A role of cyclooxygenase-2 was indicated by coincubation with the cyclooxygenase-2 inhibitor celecoxib and the cyclooxygenase-1/-2 inhibitor indomethacin, which both efficaciously abolished a glutamate-induced upregulation of MRP2. Translational studies in human capillaries from surgical specimen demonstrated a relevant MRP2 efflux function and indicated an effect of glutamate exposure as well as its prevention by cyclooxygenase-2 inhibition. Taken together the findings provide first evidence for a role of a glutamate-induced NMDA receptor/cyclooxygenase-2 signaling pathway in the regulation of MRP2 expression and function. The response to excessive glutamate concentrations might contribute to overexpression of MRP2, which has been reported in neurologic diseases including epilepsy. The overexpression might have implications for brain access of various compounds including therapeutic drugs. PMID:25503388

Luna-Munguia, Hiram; Salvamoser, Josephine D; Pascher, Bettina; Pieper, Tom; Getzinger, Thekla; Kudernatsch, Manfred; Kluger, Gerhard; Potschka, Heidrun

2015-02-01

235

A highly tumor-targeted nanoparticle of podophyllotoxin penetrated tumor core and regressed multidrug resistant tumors.  

Science.gov (United States)

Podophyllotoxin (PPT) exhibited significant activity against P-glycoprotein mediated multidrug resistant (MDR) tumor cell lines; however, due to its poor solubility and high toxicity, PPT cannot be dosed systemically, preventing its clinical use for MDR cancer. We developed a nanoparticle dosage form of PPT by covalently conjugating PPT and polyethylene glycol (PEG) with acetylated carboxymethyl cellulose (CMC-Ac) using one-pot esterification chemistry. The polymer conjugates self-assembled into nanoparticles (NPs) of variable sizes (20-120 nm) depending on the PPT-to-PEG molar ratio (2-20). The conjugate with a low PPT/PEG molar ratio of 2 yielded NPs with a mean diameter of 20 nm and released PPT at ?5%/day in serum, while conjugates with increased PPT/PEG ratios (5 and 20) produced bigger particles (30 nm and 120 nm respectively) that displayed slower drug release (?2.5%/day and ?1%/day respectively). The 20 nm particles exhibited 2- to 5-fold enhanced cell killing potency and 5- to 20-fold increased tumor delivery compared to the larger NPs. The biodistribution of the 20 nm PPT-NPs was highly selective to the tumor with 8-fold higher accumulation than all other examined tissues, while the larger PPT-NPs (30 and 120 nm) exhibited increased liver uptake. Within the tumor, >90% of the 20 nm PPT-NPs penetrated to the hypovascular core, while the larger particles were largely restricted in the hypervascular periphery. The 20 nm PPT-NPs displayed significantly improved efficacy against MDR tumors in mice compared to the larger PPT-NPs, native PPT and the standard taxane chemotherapies, with minimal toxicity. PMID:25818440

Roy, Aniruddha; Ernsting, Mark J; Undzys, Elijus; Li, Shyh-Dar

2015-06-01

236

Emr, an Escherichia coli locus for multidrug resistance.  

OpenAIRE

An Escherichia coli chromosomal DNA fragment cloned on a multicopy plasmid conferred resistance to carbonylcyanide m-chlorophenylhydrazone, nalidixic acid, and a number of other toxic compounds. The sequence of the cloned emr locus located at minute 57.5 of the chromosome revealed two open reading frames, emrA and emrB. emrB encodes a highly hydrophobic 56.2-kDa peptide, with 14 potential alpha-helices to span the inner membrane. The peptide is homologous to QacA, a multidrug-resistant pump f...

Lomovskaya, O.; Lewis, K.

1992-01-01

237

Ribozyme-mediated reversal of the multidrug-resistant phenotype.  

OpenAIRE

This study examined the effects of suppressing c-fos oncogene expression on multidrug resistance (MDR). A2780S human ovarian carcinoma cells with resistance to actinomycin D were isolated and the resultant A2780AD cells exhibited the MDR phenotype. A hammerhead ribozyme designed to cleave fos RNA cloned into the pMAMneo plasmid was transfected into A2780AD cells. Induction of the ribozyme resulted in decreased expression of c-fos, as well as that of the MDR gene (mdr-1), c-jun, and mutant p53...

Scanlon, K. J.; Ishida, H.; Kashani-sabet, M.

1994-01-01

238

Gene expression in the development of multidrug resistance  

OpenAIRE

Molecular processes involved in the development of malignancy have a role to play in the establishment of the multidrug resistant (MDR) phenotype. Analysis of oncogene expression, at the mRNA level using RT-PCR, in resistant variants of the human squamous lung cell line, DLKP, and the human ovarian carcinoma cell line, OAW42, was carried out in this study. Analysis of gene expression, by RT-PCR and in situ hybridisation, on tumours from breast cancer patients was also carried out on fresh and...

Nicamhlaoibh, Roisin

1997-01-01

239

Worldwide Occurrence of Integrative Conjugative Element Encoding Multidrug Resistance Determinants in Epidemic Vibrio cholerae O1  

OpenAIRE

In the last decades, there has been an increase of cholera epidemics caused by multidrug resistant strains. Particularly, the integrative and conjugative element (ICE) seems to play a major role in the emergence of multidrug resistant Vibrio cholerae. This study fully characterized, by whole genome sequencing, new ICEs carried by multidrug resistant V. cholerae O1 strains from Nigeria (2010) (ICEVchNig1) and Nepal (1994) (ICEVchNep1). The gene content and gene order of these two ICEs are the ...

Marin, Michel A.; Fonseca, Erica L.; Andrade, Bruno N.; Cabral, Adriana C.; Vicente, Ana Carolina P.

2014-01-01

240

Anticancer Effects of the Nitric Oxide-Modified Saquinavir Derivative Saquinavir-NO against Multidrug-Resistant Cancer Cells  

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Full Text Available The human immunodeficiency virus (HIV protease inhibitor saquinavir shows anticancer activity. Although its nitric oxide-modified derivative saquinavir-NO (saq-NO was less toxic to normal cells, it exerted stronger inhibition of B16 melanoma growth in syngeneic C57BL/6 mice than saquinavir did. Saq-NO has been shown to block proliferation, upregulate p53 expression, and promote differentiation of C6 glioma and B16 cells. The anticancer activity of substances is frequently hampered by cancer cell chemoresistance mechanisms. Therefore, we here investigated the roles of p53 and the ATP-binding cassette (ABC transporters P-glycoprotein (P-gp, multidrug resistance-associated protein 1 (MRP1, and breast cancer resistance protein 1 (BCRP1 in cancer cell sensitivity to saq-NO to get more information about the potential of saq-NO as anticancer drug. Saq-NO exerted anticancer effects in lower concentrations than saquinavir in a panel of human cancer cell lines. Neither p53 mutation or depletion nor expression of P-gp, MRP1, or BCRP1 affected anticancer activity of saq-NO or saquinavir. Moreover, saq-NO sensitized P-gp-, MRP1-, or BCRP1-expressing cancer cells to chemotherapy. Saq-NO induced enhanced sensitization of P-gp- or MRP1-expressing cancer cells to chemotherapy compared with saquinavir, whereas both substances similarly sensitized BCRP1-expressing cells. Washout kinetics and ABC transporter ATPase activities demonstrated that saq-NO is a substrate of P-gp as well as of MRP1. These data support the further investigation of saq-NO as an anticancer drug, especially in multidrug-resistant tumors.

Florian Rothweiler

2010-12-01

241

Clinical evaluation of multidrug resistance associated protein expression by FDG PET and MIBI SPECT in lung cancer  

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Multidrug resistance is one of the major obstacles in the successful anticancer therapy. The aim of this study is to evaluate whether FDG PET and MIBI SPECT can be markers for p-glycoprotein (Pgp), multidrug resistance-associated protein (MRP), lung resistance protein (LRP) expression in lung cancer tissues. Eighty-eight patients with 92 lung cancer lesions were enrolled in this study. Before surgery, FDG PET imaging was performed 40 min after injection of FDG 185 MBq, and standardized uptake values (SUVs) were obtained. MIBI SPECT imaging was performed 15 min and 3 hour after injection of MIBI 370 MBq. Early ratio (ER), delayed ratio (DR), and washout rate (WR) were obtained. Pgp, MRP, and LRP expression in lung cancer tissues were determined by immunohistochemical staining. No significant correlations were observed between MIBI uptake and expression of Pgp, MRP and LRP. FDG uptake significantly correlated with expression of Pgp and LRP. The lung cancer with high degree of Pgp and LRP expression had significantly low FDG uptake. However, there is no correlation between FDG uptake and MRP expression. Pgp and LRP expression of adenocarcinomas were significantly higher than that of squamous cell carcinomas. FDG uptake of adenocarcinomas were significantly lower than that of squamous cell carcinomas. In lung adenocarcinomas, Pgp and LRP expression of bronchioloalveolar carcinomas were significantly higher than that of poorly differentiated adenocarcinomas. In contrast, FDG uptake of bronchioloalveolar carcinomas were significantly low when compared with that of poorly differentiated adenocarcinomas. In addition, it was also suggested that biological behavior of LRP expression was similar to that of Pgp expression. FDG uptake may be a marker for Pgp and LRP expression but not for MRP expression in patients with lung cancer. Both Pgp, LRP expression and FDG uptake correlate with cellular differentiation and histological type. (author)

Kodama, Yuko [Kanazawa Medical Univ., Uchinada (Japan)

2002-09-01

242

Clinical evaluation of multidrug resistance associated protein expression by FDG PET and MIBI SPECT in lung cancer  

International Nuclear Information System (INIS)

Multidrug resistance is one of the major obstacles in the successful anticancer therapy. The aim of this study is to evaluate whether FDG PET and MIBI SPECT can be markers for p-glycoprotein (Pgp), multidrug resistance-associated protein (MRP), lung resistance protein (LRP) expression in lung cancer tissues. Eighty-eight patients with 92 lung cancer lesions were enrolled in this study. Before surgery, FDG PET imaging was performed 40 min after injection of FDG 185 MBq, and standardized uptake values (SUVs) were obtained. MIBI SPECT imaging was performed 15 min and 3 hour after injection of MIBI 370 MBq. Early ratio (ER), delayed ratio (DR), and washout rate (WR) were obtained. Pgp, MRP, and LRP expression in lung cancer tissues were determined by immunohistochemical staining. No significant correlations were observed between MIBI uptake and expression of Pgp, MRP and LRP. FDG uptake significantly correlated with expression of Pgp and LRP. The lung cancer with high degree of Pgp and LRP expression had significantly low FDG uptake. However, there is no correlation between FDG uptake and MRP expression. Pgp and LRP expression of adenocarcinomas were significantly higher than that of squamous cell carcinomas. FDG uptake of adenocarcinomas were significantly lower than that of squamous cell carcinomas. In lung adenocarcinomas, Pgp and LRP expression of bronchioloalveolar carcinomas were significantly higher than that of poorly differentiated adenocarcinomas. In contrast, Ferentiated adenocarcinomas. In contrast, FDG uptake of bronchioloalveolar carcinomas were significantly low when compared with that of poorly differentiated adenocarcinomas. In addition, it was also suggested that biological behavior of LRP expression was similar to that of Pgp expression. FDG uptake may be a marker for Pgp and LRP expression but not for MRP expression in patients with lung cancer. Both Pgp, LRP expression and FDG uptake correlate with cellular differentiation and histological type. (author)

243

Multidrug-resistant hela cells overexpressing MRP1 exhibit sensitivity to cell killing by hyperthermia: Interactions with etoposide  

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Purpose: Multidrug resistance (MDR) remains one of the primary obstacles in cancer chemotherapy and often involves overexpression of drug efflux transporters such as P-glycoprotein and multidrug resistance protein 1 (MRP1). Regional hyperthermia is undergoing clinical investigation in combination with chemotherapy or radiotherapy. This study evaluates whether hyperthermia can reverse MDR mediated by MRP1 in human cervical adenocarcinoma (HeLa) cells. Methods and materials: Cytotoxicity of hyperthermia and/or etoposide was evaluated using sulforhodamine-B in HeLa cells overexpressing MRP1 and their drug-sensitive counterparts. Glutathione, glutathione peroxidase (GPx), and glutathione S-transferase (GST) were quantified by spectrophotometry. GST isoenzymes were quantified by immunodetection. Caspase activation was evaluated by fluorometry and chromatin condensation by fluorescence microscopy using Hoechst 33258. Necrosis was determined using propidium iodide. Results: The major finding is that HeLa and HeLaMRP cells are both sensitive to cytotoxicity of hyperthermia (41-45 deg C). Hyperthermia induced activation of caspase 3 and chromatin condensation. Although total levels of cell killing were similar, there was a switch from apoptotic to necrotic cell death in MDR cells. This could be explained by decreased glutathione and GPx in MDR cells. MDR cells also contained very low levels of GST and were resistant to etoposide-induced apoptosis. Hyperthermia caused a modest d apoptosis. Hyperthermia caused a modest increase in etoposide-induced apoptosis in HeLa and HeLaMRP cells, which required appropriate heat-drug scheduling. Conclusions: Hyperthermia could be useful in eliminating MDR cells that overexpress MRP1

244

Biodegradable cationic polymeric nanocapsules for overcoming multidrug resistance and enabling drug-gene co-delivery to cancer cells  

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Having unique architectural features, cationic polymeric nanocapsules (NCs) with well-defined covalently stabilized biodegradable structures were generated as potentially universal and safe therapeutic nanocarriers. These NCs were synthesized from allyl-functionalized cationic polylactide (CPLA) by highly efficient UV-induced thiol-ene interfacial cross-linking in transparent miniemulsions. With tunable nanoscopic sizes, negligible cytotoxicity and remarkable degradability, they are able to encapsulate doxorubicin (Dox) with inner cavities and bind interleukin-8 (IL-8) small interfering RNA (siRNA) with cationic shells. The Dox-encapsulated NCs can effectively bypass the P-glycoprotein (Pgp)-mediated multidrug resistance of MCF7/ADR cancer cells, thereby resulting in increased intracellular drug concentration and reduced cell viability. In vitro studies also showed that the NCs loaded with Dox, IL-8 siRNA and both agents can be readily taken up by PC3 prostate cancer cells, resulting in a significant chemotherapeutic effect and/or IL-8 gene silencing.Having unique architectural features, cationic polymeric nanocapsules (NCs) with well-defined covalently stabilized biodegradable structures were generated as potentially universal and safe therapeutic nanocarriers. These NCs were synthesized from allyl-functionalized cationic polylactide (CPLA) by highly efficient UV-induced thiol-ene interfacial cross-linking in transparent miniemulsions. With tunable nanoscopic sizes, negligible cytotoxicity and remarkable degradability, they are able to encapsulate doxorubicin (Dox) with inner cavities and bind interleukin-8 (IL-8) small interfering RNA (siRNA) with cationic shells. The Dox-encapsulated NCs can effectively bypass the P-glycoprotein (Pgp)-mediated multidrug resistance of MCF7/ADR cancer cells, thereby resulting in increased intracellular drug concentration and reduced cell viability. In vitro studies also showed that the NCs loaded with Dox, IL-8 siRNA and both agents can be readily taken up by PC3 prostate cancer cells, resulting in a significant chemotherapeutic effect and/or IL-8 gene silencing. Electronic supplementary information (ESI) available: Experimental section and Fig. S1-S6. See DOI: 10.1039/c3nr04804g

Chen, Chih-Kuang; Law, Wing-Cheung; Aalinkeel, Ravikumar; Yu, Yun; Nair, Bindukumar; Wu, Jincheng; Mahajan, Supriya; Reynolds, Jessica L.; Li, Yukun; Lai, Cheng Kee; Tzanakakis, Emmanuel S.; Schwartz, Stanley A.; Prasad, Paras N.; Cheng, Chong

2014-01-01

245

Overexpression of the Response Regulator evgA of the Two-Component Signal Transduction System Modulates Multidrug Resistance Conferred by Multidrug Resistance Transporters  

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Overexpression of evgA, a response regulator of a two-component system, increased multidrug efflux in Escherichia coli. Since overexpression of the emrKY operon, which is controlled by evgAS, could account only for deoxycholate resistance, the evgAS locus apparently controls expression of at least one other multidrug efflux operon.

Nishino, Kunihiko; Yamaguchi, Akihito

2001-01-01

246

Multidrug resistance protein gene expression in Trichoplusia ni caterpillars.  

Science.gov (United States)

Many insect species exhibit pesticide-resistant phenotypes. One of the mechanisms capable of contributing to resistance is the overexpression of multidrug resistance (MDR) transporter proteins. Here we describe the cloning of three genes encoding MDR proteins from Trichoplusia ni: trnMDR1, trnMDR2 and trnMDR3. Real-time quantitative PCR (qPCR) detected trnMDR mRNA in the whole nervous system, midgut and Malpighian tubules of final instar T.?ni caterpillars. To test whether these genes are upregulated in response to chemical challenge in this insect, qPCR was used to compare trnMDR mRNA levels in unchallenged insects with those of insects fed the synthetic pyrethroid, deltamethrin. Only limited increases were detected in a single gene, trnMDR2, which is the most weakly expressed of the three MDR genes, suggesting that increased multidrug resistance of this type is not a significant part of the response to deltamethrin exposure. PMID:23170973

Simmons, Jason; D'Souza, Olivia; Rheault, Mark; Donly, Cam

2013-02-01

247

Luteolin induces apoptosis in multidrug resistant cancer cells without affecting the drug transporter function: involvement of cell line-specific apoptotic mechanisms  

Science.gov (United States)

Bioflavonoids are of considerable interest to human health as these serve as antioxidant and anticancer agents. Although epidemiological and experimental studies suggest that luteolin, a natural bioflavonoid, exhibits chemopreventive properties, its effectiveness as an antiproliferative agent against multidrug resistant (MDR) cancers is unclear. We thus assessed the antiproliferative effects of luteolin and associated molecular mechanisms using two MDR cancer cell lines that express high levels of P-glycoprotein and ABCG2. In this paper, we demonstrate that luteolin induces apoptosis in P-glycoprotein- and ABCG2-expressing MDR cancer cells without affecting the transport functions of these drug transporters. Analysis of various proliferative signaling pathways indicated that luteolin-induced apoptosis involves reactive oxygen species generation, DNA damage, activation of ATR?Chk2?p53 signaling pathway, inhibition of NF-kB signaling pathway, activation of p38 pathway and depletion of anti-apoptotic proteins. Importantly, use of luteolin in these analyses also identified specific molecular characteristics of NCI-ADR/RES and MCF-7/MitoR cells that highlight their different tissue origins. These results suggest that luteolin possesses therapeutic potential to control the proliferation of MDR cancers without affecting the physiological function of drug transporters in the body tissues. PMID:21792893

Rao, Prema S.; Satelli, Arun; Moridani, Majid; Jenkins, Marjorie; Rao, U. Subrahmanyeswara

2011-01-01

248

Inhibition of the Emergence of Ciprofloxacin Resistance in Streptococcus pneumoniae by the Multidrug Efflux Inhibitor Reserpine  

OpenAIRE

Recent evidence supports the contribution of a multidrug efflux mechanism to fluoroquinolone resistance in Streptococcus pneumoniae. In this paper I show that reserpine, an inhibitor of multidrug transporters in gram-positive bacteria, dramatically suppresses the in vitro emergence of ciprofloxacin-resistant variants of S. pneumoniae, suggesting that the combination of a fluoroquinolone with an inhibitor of multidrug transport may help preserve the efficacy of this class of antibiotics.

Markham, Penelope N.

1999-01-01

249

Multidrug-Resistant Tuberculosis in Europe, 2010–2011  

Science.gov (United States)

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 resistant to pyrazinamide, 51.1% were resistant to ?1 second-line drug, 26.6% were resistant to second-line injectable drugs, 17.6% were resistant to fluoroquinolones, and 6.8% were extensively drug resistant. Previous treatment for TB was the strongest risk factor for MDR TB. High levels of primary transmission and advanced resistance to second-line drugs characterize MDR TB cases in Europe. PMID:25693485

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

2015-01-01

250

Human Multidrug Resistance 1 gene polymorphisms and Idiopathic Pulmonary Fibrosis  

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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

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

2015-01-01

251

Multidrug-resistant bacteroides fragilis--Seattle, Washington, 2013.  

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The Bacteroides fragilis group consists of species of obligate anaerobic bacteria that inhabit the human gut. They are among the leading pathogens isolated in the setting of intra-abdominal infections. B. fragilis strains, especially in the United States, are virtually always susceptible to metronidazole, carbapenems, and beta-lactam antibiotics. Although isolated cases of resistance to single agents have been reported, multidrug-resistant (MDR) B. fragilis strains are exceptionally rare. In May 2013, an MDR B. fragilis strain was isolated from the bloodstream and intra-abdominal abscesses of a patient who had recently received health care in India. This is only the second published case of MDR B. fragilis in the United States. This report summarizes the case and highlights the need for awareness of multidrug-resistant organisms (MDROs) in returning travelers who have received inpatient medical care outside the United States, both for timely implementation of proper infection control measures and to ensure administration of appropriate antimicrobials. PMID:23985497

2013-08-30

252

Characterization of a multidrug resistant C. difficile meat isolate.  

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Clostridium difficile is a pathogen of significant public health concern causing a life-threatening, toxin-mediated enteric disease in humans. The incidence and severity of the disease associated with C. difficile have increased in the US with the emergence of hypervirulent strains and community associated outbreaks. The detection of genotypically similar and identical C. difficile strains implicated from human infections in foods and food animals indicates the potential role of food as a source of community associated C. difficile disease. One hundred samples each of ground beef, pork and chicken obtained from geographically distant grocery stores in Connecticut were tested for C. difficile. Positive isolates were characterized by ribotyping, antibiotic susceptibility, toxin production and whole genome sequencing. Of the 300 meat samples, only two pork samples tested positive for C. difficile indicating a very low prevalence of C. difficile in meat. The isolates were non toxigenic; however, genome characterization revealed the presence of several antibiotic resistance genes and mobile elements that can potentially contribute to generation of multidrug resistant toxigenic C. difficile by horizontal gene transfer. Further studies are warranted to investigate potential food-borne transmission of the meat isolates and development of multi-drug resistance in these strains. PMID:25440554

Mooyottu, Shankumar; Flock, Genevieve; Kollanoor-Johny, Anup; Upadhyaya, Indu; Jayarao, Bhushan; Venkitanarayanan, Kumar

2015-01-01

253

Draft Genome Sequence of Multidrug Resistant Salmonella enterica serovar Weltevreden Isolated from Seafood  

Science.gov (United States)

Salmonella enterica subsp. enterica serovar Weltevereden is the most frequent serovar isolated from Asia. Here, we report a draft genome sequence of multidrug resistant Salmonella Weltevreden 9 isolated from seafood. Whole-genome of this isolate and annotation will help enhance the understanding of this pathogenic multidrug-resistant serovar. PMID:25874015

Deekshit, Vijaya Kumar; Ballamoole, Krishna Kumar; Rai, Praveen; Madhushankara; Karunasagar, Iddya; Karunasagar, Indrani

2015-01-01

254

Multidrug-Resistant Pandemic (H1N1) 2009 Infection in Immunocompetent Child  

OpenAIRE

Recent case reports describe multidrug-resistant influenza A pandemic (H1N1) 2009 virus infection in immunocompromised patients exposed to neuraminidase inhibitors because of an I223R neuraminidase mutation. We report a case of multidrug-resistant pandemic (H1N1) 2009 bearing the I223R mutation in an ambulatory child with no previous exposure to neuraminidase inhibitors.

Eshaghi, Alireza; Patel, Samir N.; Sarabia, Alicia; Higgins, Rachel R.; Savchenko, Alexei; Stojios, Peter J.; Li, Yan; Bastien, Nathalie; Alexander, David C.; Low, Donald E.; Gubbay, Jonathan B.

2011-01-01

255

p-Glycoprotein ABCB5 and YB-1 expression plays a role in increased heterogeneity of breast cancer cells: correlations with cell fusion and doxorubicin resistance  

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Full Text Available Abstract Background Cancer cells recurrently develop into acquired resistance to the administered drugs. The iatrogenic mechanisms of induced chemotherapy-resistance remain elusive and the degree of drug resistance did not exclusively correlate with reductions of drug accumulation, suggesting that drug resistance may involve additional mechanisms. Our aim is to define the potential targets, that makes drug-sensitive MCF-7 breast cancer cells turn to drug-resistant, for the anti-cancer drug development against drug resistant breast cancer cells. Methods Doxorubicin resistant human breast MCF-7 clones were generated. The doxorubicin-induced cell fusion events were examined. Heterokaryons were identified and sorted by FACS. In the development of doxorubicin resistance, cell-fusion associated genes, from the previous results of microarray, were verified using dot blot array and quantitative RT-PCR. The doxorubicin-induced expression patterns of pro-survival and pro-apoptotic genes were validated. Results YB-1 and ABCB5 were up regulated in the doxorubicin treated MCF-7 cells that resulted in certain degree of genomic instability that accompanied by the drug resistance phenotype. Cell fusion increased diversity within the cell population and doxorubicin resistant MCF-7 cells emerged probably through clonal selection. Most of the drug resistant hybrid cells were anchorage independent. But some of the anchorage dependent MCF-7 cells exhibited several unique morphological appearances suggesting minor population of the fused cells maybe de-differentiated and have progenitor cell like characteristics. Conclusion Our work provides valuable insight into the drug induced cell fusion event and outcome, and suggests YB-1, GST, ABCB5 and ERK3 could be potential targets for the anti-cancer drug development against drug resistant breast cancer cells. Especially, the ERK-3 serine/threonine kinase is specifically up-regulated in the resistant cells and known to be susceptible to synthetic antagonists.

Yang Yun-Sik

2010-07-01

256

Identification of proteins associated to multi-drug resistance in LoVo human colon cancer cells.  

Science.gov (United States)

Multi-drug resistance (MDR) limits the effectiveness of chemotherapy. P-glycoprotein encoded by the MDR1 gene, is known to be implicated in MDR phenotype, but other factors could be determinant in MDR. The aim of this study was to investigate new molecular factors potentially associated with the MDR phenotype using a proteomic approach. Two dimensional fluorescence difference gel electrophoresis (2D-DIGE) and MALDI-TOF peptide mass fingerprinting were used to determine differentially expressed proteins between LoVo human colon carcinoma cell line and one of its MDR sublines (LoVo-R1). Thirty-four differentially expressed proteins were identified. They were classified into five groups based on their biological functions: i) proteins involved in energy request pathways, ii) in detoxification pathways, iii) in cell survival activity, iv) in drug transport and v) in chaperone functions. Among these proteins, endothelin 1 and proteasome subunit beta2 regulations were validated by immunofluorescence and Western blotting, respectively, showing complete consistency with 2D-DIGE results. In conclusion, the proteomic approach indicates that multiple mechanisms are simultaneously involved in MDR. These might be useful in the search for new forms of interventional therapeutic approaches for MDR reversal. PMID:19360340

Visentin, Michele; Simula, Maria Paola; Sartor, Franca; Petrucco, Alessandra; De Re, Valli; Toffoli, Giuseppe

2009-05-01

257

Regorafenib Is Transported by the Organic Anion Transporter 1B1 and the Multidrug Resistance Protein 2.  

Science.gov (United States)

Regorafenib is a small molecule inhibitor of tyrosine kinases, and has been shown to improve the outcomes of patients with advanced colorectal cancer and advanced gastrointestinal stromal tumors. The transport profiles of regorafenib by various transporters were evaluated. HEK293/organic anion transporting polypeptide 1B1 (OATP1B1) cells exhibited increased drug sensitivity to regorafenib. Regorafenib inhibited the uptake of (3)H-estrone sulfate by HEK293/OATP1B1 cells in a dose-dependent manner, but did not affect its elimination by P-glycoproteins. The concentration of regorafenib was significantly lower in LLC-PK1/multidrug resistance protein 2 (MRP2) cells than in LLC-PK1 cells treated with the MRP2 inhibitor, MK571. MK571 abolished the inhibitory effects of regorafenib on intracellular accumulation in LLC-PK1/MRP2 cells. The uptake of regorafenib was significantly higher in HEK293/OATP1B1 cells than in OATP1B1-mock cells. Transport kinetics values were estimated to be Km=15.9?µM and Vmax=1.24?nmol/mg/min. No significant difference was observed in regorafenib concentrations between HEK293/OATP1B3 and OATP1B3-mock cells. These results indicated that regorafenib is a substrate for MRP2 and OATP1B1, and also suggest that the substrate preference of regorafenib may implicate the pharmacokinetic profiles of regorafenib. PMID:25739790

Ohya, Hiroki; Shibayama, Yoshihiko; Ogura, Jiro; Narumi, Katsuya; Kobayashi, Masaki; Iseki, Ken

2015-04-01

258

Modulation of a Schistosoma mansoni multidrug transporter by the antischistosomal drug praziquantel  

OpenAIRE

P-glycoprotein (Pgp) is an ATP-dependent efflux pump involved in transport of xenobiotics from cells that, when overexpressed, can mediate multidrug resistance in mammalian cells. Pgp may be a candidate target for new anthelmintics, as it plays critical roles in normal cell physiology, in removal of drugs from cells, and potentially in the development of drug resistance. Schistosomes are parasitic flatworms that cause schistosomiasis, which affects hundreds of millions of people worldwide. He...

Kasinathan, Ravi S.; Goronga, Tinopiwa; Messerli, Shanta M.; Webb, Thomas R.; Greenberg, Robert M.

2010-01-01

259

Functional imaging of multidrug resistance in an orthotopic model of osteosarcoma using {sup 99m}Tc-sestamibi  

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The purpose of this work was the development of an orthotopic model of osteosarcoma based on luciferase-expressing tumour cells for the in vivo imaging of multidrug resistance (MDR) with {sup 99m}Tc-sestamibi. Doxorubicin-sensitive (143B-luc{sup +}) and resistant (MNNG/HOS-luc{sup +}) osteosarcoma cell lines expressing different levels of P-glycoprotein and carrying a luciferase reporter gene were inoculated into the tibia of nude mice. Local tumour growth was monitored weekly by bioluminescence imaging and X-ray. After tumour growth, a {sup 99m}Tc-sestamibi dynamic study was performed. A subset of animals was pre-treated with an MDR inhibitor (PSC833). Images were analysed for calculation of {sup 99m}Tc-sestamibi washout half-life (t{sub 1/2}), percentage washout rate (%WR) and tumour/non-tumour (T/NT) ratio. A progressively increasing bioluminescent signal was detected in the proximal tibia after 2 weeks. The t{sub 1/2} of {sup 99m}Tc-sestamibi was significantly shorter (p < 0.05) in drug-resistant MNNG/HOS-luc{sup +} tumours (t{sub 1/2} = 87.3 {+-} 15.7 min) than in drug-sensitive 143B-luc{sup +} tumours (t{sub 1/2} = 161.0 {+-} 47.4 min) and decreased significantly with PSC833 (t{sub 1/2} = 173.0 {+-} 24.5 min, p < 0.05). No significant effects of PSC833 were observed in 143B-luc{sup +} tumours. The T/NT ratio was significantly lower (p < 0.05) in MNNG/HOS-luc{sup +} tumours than in 143B-luc{sup +} tumours at early (1.55 {+-} 0.22 vs 2.14 {+-} 0.36) and delayed times (1.12 {+-} 0.11 vs 1.62 {+-} 0.33). PSC833 had no significant effects on the T/NT ratios of either tumour. The orthotopic injection of tumour cells provides an animal model suitable for functional imaging of MDR. In vivo bioluminescence imaging allows the non-invasive monitoring of tumour growth. The kinetic analysis of {sup 99m}Tc-sestamibi washout provides information on the functional activity of MDR related to P-glycoprotein expression and its pharmacological inhibition in osteosarcoma. (orig.)

Gomes, Celia M.F. [Leiden University Medical Center, Department of Radiology, Section of Nuclear Medicine, Leiden (Netherlands); Institute of Biophysics/Biomathematics, IBILI - Faculty of Medicine, Coimbra (Portugal); Welling, Mick; Pauwels, Ernest K.J. [Leiden University Medical Center, Department of Radiology, Section of Nuclear Medicine, Leiden (Netherlands); Que, Ivo; Henriquez, Niek V.; Pluijm, Gabri van der [Leiden University Medical Center, Department of Endocrinology, Leiden (Netherlands); Romeo, Salvatore; Hogendoorn, Pancras C.W.; Cleton-Jansen, Anne M. [Leiden University Medical Center, Department of Pathology, Leiden (Netherlands); Abrunhosa, Antero J.; Botelho, M.F. [Institute of Biophysics/Biomathematics, IBILI - Faculty of Medicine, Coimbra (Portugal)

2007-11-15

260

Characterization and Identification of Multidrug Resistant Bacteria from Some Egyptian Patients  

Directory of Open Access Journals (Sweden)

Full Text Available The isolation of multidrug resistant bacteria from Egyptian patients showed a great interest to study such phenomenon. Hence, simple methods were followed herein to isolate and characterize the antibiotic resistant variants by the common phenotypic, morphological and biochemical characters. Out of 500 clinical bacterial cultures, 50 only were multidrug resistant bacteria with a value of drug resistance ability of about 10%. About 46% of multidrug resistant bacterial cultures tested were isolated from urine samples. The percentage values of both resistance and susceptibility of the 50 multidrug resistant bacterial isolates to 14 types of antibiotics were calculated. Based on their cultural, morphological and biochemical characteristics, the 50 multidrug resistant bacterial isolates were identified and categorized into eight groups. The identified bacterial species were arranged in a descending order according to their frequency percentage viz. Escherichia coli>Staphylococcus aureus> Pseudomonas aeruginosa> Klebsiella pneumoniae>Streptococcus pyogenes> Proteus vulgaris>Streptococcus pneumoniae> Staphylococcus saprophyticus. The relationship between pathogenic cases, symptoms and the identified multidrug bacterial pathogens was studied. A simple key was designed for easy differentiation and classification of the 50 multidrug resistant bacterial organisms. It was based on easily determinable characteristics which were used for rapid assignment of bacteria into genera and species.

Seham Abdel-Shafi

2013-01-01

261

Differential effects of the organochlorine pesticide DDT and its metabolite p,p'-DDE on p-glycoprotein activity and expression  

International Nuclear Information System (INIS)

1,1-Bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT) is an organochlorine pesticide. Its metabolite, 1,1-dichloro-2,2-bis(p-chlorophenyl)-ethene (p,p'-DDE) is a persistent environmental contaminant and both compounds accumulate in animals. Because multidrug resistance transporters, such as p-glycoprotein, function as a defense against xenobiotic exposure, we analyzed the ability of DDT and p,p'-DDE to act as efflux modulators. Using a competitive intact cell assay based on the efflux of the fluorescent dye rhodamine 123, we found that DDT, but not p,p'-DDE, stimulated dye retention. Subsequent studies using verapamil as competitor suggested that DDT is a weak p-glycoprotein inhibitor. Further studies addressed the ability of DDT and p,p'-DDE to induce MDR1, the gene encoding p-glycoprotein. In HepG2 cells, we found that both compounds induced MDR1 by twofold to threefold. Similar results were observed in mouse liver after a single dose of p,p'-DDE, although some gender-specific induction differences were noted. By contrast, p,p'-DDE failed to induce MDR1 in HeLa cells, indicating some cell-specific effects for induction. Further expression studies demonstrated increased levels of the endoplasmic reticulum molecular chaperone, Bip, in response to DDT, but not p,p'-DDE. These results suggest that DDT, but not p,p'-DDE, induces an endoplasmic reticulum stress response

262

Expression of multidrug resistance proteins in invasive ductal carcinoma of the breast.  

Science.gov (United States)

Chemotherapy is commonly used for the treatment of breast cancer. However, the resistance to chemotherapeutic agents, often mediated by multidrug resistance (MDR) mechanisms, is a common occurrence. The present study examined the expression of several MDR-related proteins (MRPs) in invasive ductal carcinoma (IDC) of the breast, and assessed their association with clinicopathological variables and their prognostic significance. In addition, immunohistochemistry was used to measure the expression of MRP, p-glycoprotein (P-gp), topoisomerase 2? (Topo2?), thymidylate synthase (TS) and glutathione-S-transferase ? (GST-?) in 156 resected IDCs of the breast. Pearson's ?(2) test and Spearman's correlation coefficient were used to analyze the association between MDR protein expression and several clinicopathological variables. The association between each of the five MDR proteins was also examined. Furthermore, Kaplan-Meier analysis and Cox regression modeling were used to assess overall survival. The expression of MRP, P-gp, Topo2?, TS and GST-? was detected in 20.5% (32/156), 25.0% (39/156), 84.0% (131/156), 41.7% (65/156) and 41.0% (64/156) of cases examined, respectively. No correlation was identified between MRP and Topo-2? and the clinicopathological variables examined. By contrast, P-gp (?(2)=20.226; P<0.0001) and GST-? (?(2)=35.032; P<0.0001) were found to positively correlate with tumor grade. In addition, staining for TS was associated with axillary lymph node metastasis (?(2)=42.281; P<0.0001). The expression levels of P-gp and GST-? were found to be significantly correlated (r= 0.319; P<0.0001). Furthermore, GST-? expression was elevated in estrogen receptor-negative breast cancer (?(2)=17.407; P<0.0001). Tumor histological grade, in addition to TS and GST-? expression, were significant predictors of a poor survival outcome. TS and GST-? are consequently useful prognostic biomarkers in IDC, therefore, when establishing a personalized chemotherapeutic plan, the expression of MDR proteins must be considered. PMID:25295098

Li, Weiquan; Song, Maomin

2014-11-01

263

Upregulation of Stat1-HDAC4 confers resistance to etoposide through enhanced multidrug resistance 1 expression in human A549 lung cancer cells.  

Science.gov (United States)

Despite efforts to develop efficient chemotherapeutic drug strategies to treat cancer, acquired drug resistance is a commonly encountered problem. In the present study, to investigate this phenomenon, human A549 lung cancer cells resistant to the topoisomerase inhibitor etoposide (A549RT?eto) were used and compared with A549 parental cells. A549RT?eto cells demonstrated increased resistance to etoposide?induced apoptosis when compared with A549 parental cells. Notably, A549RT?eto cells were observed to exhibit greater levels of histone deacetylase 4 (HDAC4), phospho?Stat1 and P?glycoprotein [P?gp; encoded by the multidrug resistance 1 (MDR1) gene], compared with A549 cells. To address whether HDAC4 protein is involved in etoposide resistance in A549 cells, A549RT?eto cells were treated with trichostatin A (TSA; an HDAC inhibitor) during etoposide treatment. The combined treatment was demonstrated to enhance etoposide?induced apoptosis and reduce expression levels of HDAC4, P?gp and phospho?Stat1. In addition, the suppression of Stat1 with siRNA enhanced etoposide?induced apoptosis and reduced the expression levels of HDAC4 and P?gp, suggesting that Stat1 is essential in the regulation of resistance to etoposide, and in the upregulation of P?gp. Notably, TSA treatment reduced P?gp transcript levels but Stat1 siRNA treatment did not, suggesting that P?gp is regulated by HDAC at the transcriptional level and by Stat1 at the post?transcriptional level. These results suggest that the upregulation of Stat1 and HDAC4 determines etoposide resistance through P?gp expression in human A549 lung cancer cells. PMID:25395162

Kaewpiboon, Chutima; Srisuttee, Ratakorn; Malilas, Waraporn; Moon, Jeong; Oh, Sangtaek; Jeong, Hye Gwang; Johnston, Randal N; Assavalapsakul, Wanchai; Chung, Young-Hwa

2015-03-01

264

Effects of Astragalus polysaccharides on P-glycoprotein efflux pump function and protein expression in H22 hepatoma cells in vitro  

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Full Text Available Abstract Background Astragalus polysaccharides (APS are active constituents of Astragalus membranaceus. They have been widely studied, especially with respect to their immunopotentiating properties, their ability to counteract the side effects of chemotherapeutic drugs, and their anticancer properties. However, the mechanism by which APS inhibit cancer and the issue of whether that mechanism involves the reversal of multidrug resistance (MDR is not completely clear. The present paper describes an investigation of the effects of APS on P-glycoprotein function and expression in H22 hepatoma cell lines resistant to Adriamycin (H22/ADM. Methods H22/ADM cell lines were treated with different concentrations of APS and/or the most common chemotherapy drugs, such as Cyclophosphamid, Adriamycin, 5-Fluorouracil, Cisplatin, Etoposide, and Vincristine. Chemotherapeutic drug sensitivity, P-glycoprotein function and expression, and MDR1 mRNA expression were detected using MTT assay, flow cytometry, Western blotting, and quantitative RT-PCR. Results When used alone, APS had no anti-tumor activity in H22/ADM cells in vitro. However, it can increase the cytotoxicity of certain chemotherapy drugs, such as Cyclophosphamid, Adriamycin, 5-Fluorouracil, Cisplatin, Etoposide, and Vincristine, in H22/ADM cells. It acts in a dose-dependent manner. Compared to a blank control group, APS increased intracellular Rhodamine-123 retention and decreased P-glycoprotein efflux function in a dose-dependent manner. These factors were assessed 24?h, 48?h, and 72?h after administration. APS down regulated P-glycoprotein and MDR1 mRNA expression in a concentration-dependent manner within a final range of 0.8–500?mg/L and in a time-dependent manner from 24–72?h. Conclusion APS can enhance the chemosensitivity of H22/ADM cells. This may involve the downregulation of MDR1 mRNA expression, inhibition of P-GP efflux pump function, or both, which would decrease the expression of the MDR1 protein.

Tian Qing E

2012-07-01

265

Role of old antibiotics in multidrug resistant bacterial infections.  

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Multidrug resistant bacteria infections are associated with an increase in attributable mortality and morbidity in ICU patients. Unfortunately, an emerging resistance to novel antibiotics used in the therapy of gram negative and gram positive bacteria infections is often reported in literature. Old antibiotics have been reintroduced in clinical practice. In this review we report the efficacy and safety use of older antimicrobial agents in critically ill patients. Polymyxins are used for nosocomial infection caused by Pseudomonas aeruginosa and Acinetobacter baumannii resistant strains. Patients with polymyxin-only susceptible gram-negative nosocomial pneumonia are reported to be successfully treated with inhaled colistin. Isepamicin can probably be used in intensive care units that harbor Gram-negative bacteria resistant to other aminoglycosides. Fosfomycin may be a useful alternative to linezolid and quinupristin-dalfopristin in the treatment of Vancomycin Resistant Enterococci (VRE) infections in certain clinical situations, e.g. uncomplicated urinary tract infections. Chloramphenicol has a wide antimicrobial spectrum and excellent tissue penetration; though it is sometimes used empirically in the hospital setting for the treatment of patients with unknown source of fever, its role is still a matter of controversy. The colistin/rifampicin combination might have a synergistic effect in Acinetobacter baumannii and Pseudomonas aeruginosa infections. Fusidic acid is active against staphylococcal strains. PMID:19799544

Maviglia, R; Nestorini, R; Pennisi, M

2009-09-01

266

Purification of a Multidrug Resistance Transporter for Crystallization Studies  

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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.

Kamela O. Alegre

2015-03-01

267

The Pim kinase inhibitor SGI-1776 decreases cell surface expression of P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2) and drug transport by Pim-1-dependent and -independent mechanisms.  

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Overexpression of the ATP-binding cassette (ABC) drug efflux proteins P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2) on malignant cells is associated with inferior chemotherapy outcomes. Both, ABCB1 and ABCG2, are substrates of the serine/threonine kinase Pim-1; Pim-1 knockdown decreases their cell surface expression, but SGI-1776, the first clinically tested Pim inhibitor, was shown to reverse drug resistance by directly inhibiting ABCB1-mediated transport. We sought to characterize Pim-1-dependent and -independent effects of SGI-1776 on drug resistance. SGI-1776 at the Pim-1-inhibitory and non-cytotoxic concentration of 1 ?M decreased the IC(50)s of the ABCG2 and ABCB1 substrate drugs in cytotoxicity assays in resistant cells, with no effect on the IC(50) of non-substrate drug, nor in parental cells. SGI-1776 also increased apoptosis of cells overexpressing ABCG2 or ABCB1 exposed to substrate chemotherapy drugs and decreased their colony formation in the presence of substrate, but not non-substrate, drugs, with no effect on parental cells. SGI-1776 decreased ABCB1 and ABCG2 surface expression on K562/ABCB1 and K562/ABCG2 cells, respectively, with Pim-1 overexpression, but not HL60/VCR and 8226/MR20 cells, with lower-level Pim-1 expression. Finally, SGI-1776 inhibited uptake of ABCG2 and ABCB1 substrates in a concentration-dependent manner irrespective of Pim-1 expression, inhibited ABCB1 and ABCG2 photoaffinity labeling with the transport substrate [(125)I]iodoarylazidoprazosin ([(125)I]IAAP) and stimulated ABCB1 and ABCG2 ATPase activity. Thus SGI-1776 decreases cell surface expression of ABCB1 and ABCG2 and inhibits drug transport by Pim-1-dependent and -independent mechanisms, respectively. Decrease in ABCB1 and ABCG2 cell surface expression mediated by Pim-1 inhibition represents a novel mechanism of chemosensitization. PMID:23261525

Natarajan, Karthika; Bhullar, Jasjeet; Shukla, Suneet; Burcu, Mehmet; Chen, Zhe-Sheng; Ambudkar, Suresh V; Baer, Maria R

2013-02-15

268

From mixed sigma-2 receptor/P-glycoprotein targeting agents to selective P-glycoprotein modulators: small structural changes address the mechanism of interaction at the efflux pump.  

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Generations of modulators of the efflux pump P-glycoprotein (P-gp) have been produced as tools to counteract the Multidrug Resistance (MDR) phenomenon in tumor therapy, but clinical trials were not successful so far. With the aim of contributing to the development of novel P-gp modulators, we started from recently studied high-affinity sigma-2 (?2) receptor ligands that showed also potent interaction with P-gp. For ?2 receptors high-affinity binding, a basic N-atom is a strict requirement. Therefore, we reduced the basic character of the N-atom present in these ligands, and we obtained potent P-gp modulators with poor or null ?2 receptor affinity. We also evaluated whether modulation of P-gp by these novel compounds involved consumption of ATP (as P-gp substrates do), as a source of energy to support the efflux. Surprisingly, even small structural changes resulted in opposite behavior, with amide 13 depleting ATP, in contrast to its isomer 18. Two compounds, 15 and 25, emerged for their potent activity at P-gp, and deserve further investigations as tools for P-gp modulation. PMID:25462269

Abate, Carmen; Pati, Maria Laura; Contino, Marialessandra; Colabufo, Nicola Antonio; Perrone, Roberto; Niso, Mauro; Berardi, Francesco

2015-01-01

269

Imaging multidrug resistance with 4-[18F]fluoropaclitaxel  

International Nuclear Information System (INIS)

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 mea step toward image-guided personalized medicine

270

Bacteriophages: biosensing tools for multi-drug resistant pathogens.  

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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. PMID:24434867

Tawil, N; Sacher, E; Mandeville, R; Meunier, M

2014-03-21

271

P-glycoprotein down-regulates the X-ray-induced apoptosis of a drug-resistant tumor cell line MCF-7/Adr  

International Nuclear Information System (INIS)

Objective: To investigate the regulatory effect of P-gp on X-ray-induced apoptosis of drug-resistant tumor cells. Methods: Anti-P-gp McAb was applied to block P-gp function. MCF-7/Adr, a P-gp-over-expressing drug-resistant breast cancer cell line, was irradiated with X-rays. Flow cytometry was performed to examine dynamic changes of apoptotic ratio and mitochondrial membrane potential (??m) at various times after X-ray irradiation. Results: Apoptotic ratio of the P-gp-blocked group was 25.53%±2.85 %; 30.43%±2.21%; 39.03% ±2.60%, and of the control group was 16.13%±1.16%; 21.73%±1.31%; 27.53%±2.55% at 6 h,12 h, 24 h, respectively, after X-ray irradiation. The apoptotic ratio of the P-gp-blocked group was significantly up-regulated, as compared with that of the control group (P<0.01). The mitochondrial membrane potential (??m) of both the P-gp-blocked group and the control group was decreased, but the ??m of the P-gp-blocked group was significantly lower than that of the control group (P<0.01 ). Conclusion: P-gp down-regulates the X-ray-induced apoptosis of the drug-resistant MCF-7/Adr cells and elevates the mitochondrial membrane potential (??m)

272

Characterization of a multidrug resistant Teladorsagia circumcincta isolate from Spain.  

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The aim of this work was to know the anthelmintic resistance (AR) status of a Spanish sheep flock infected by gastrointestinal nematodes (GIN) and the possible cross resistance among anthelmintics of the macrocyclic lactones (ML) family. The Faecal Egg Count Reduction Test (FECRT) was carried out to check the efficacy of albendazole (Zodalben®), levamisole (LEV) (Endex®) and an oral formulation of ivermectin (IVM) (Oramec®), at the recommended dose rates. Then, the study was extended to check the cross resistance between drugs of the ML family: injectable IVM (Ivomec®), oral moxidectin (Cydectin®), injectable moxidectin (Biodectin®) and doramectin (Dectomax®), at the recommended dose rates. The GIN species were identified after faecal cultures in all groups. The FECRT showed the resistance of a Teladorsagia circumcincta isolate against LEV (39-58%), IVM (88-92%) and doramectin (85%). This study is the first report to confirm the side resistance between these MLs, which belong to the avermectin chemical group, in a Spanish sheep flock. The in vitro efficacy of LEV and IVM was measured by the Larval Feeding Inhibition Assay (LFIA) using the IC(50) measurement (concentration needed to inhibit the ingestion of 50% L1). The values of the multidrug resistant isolate were 0.25 ?g/ml for LEV and 3 ng/ml for IVM. Both results were higher than the values obtained with a susceptible isolate, which could be indicative of AR. However, further research examining the response of a greater range of susceptible and resistant nematodes isolates should be carried out to establish a discrimination threshold. PMID:22179266

Martínez-Valladares, M; Famularo, M R; Fernández-Pato, N; Cordero-Pérez, C; Castañón-Ordóñez, L; Rojo-Vázquez, F A

2012-05-01

273

Effect of NlpE Overproduction on Multidrug Resistance in Escherichia coli?  

OpenAIRE

NlpE, an outer membrane lipoprotein, functions during envelope stress responses in Gram-negative bacteria. In this study, we report that overproduction of NlpE increases multidrug and copper resistance through activation of the genes encoding the AcrD and MdtABC multidrug efflux pumps in Escherichia coli.

Nishino, Kunihiko; Yamasaki, Seiji; Hayashi-nishino, Mitsuko; Yamaguchi, Akihito

2010-01-01

274

Multidrug Resistance-Associated Protein 1 (MRP1) mediated vincristine resistance: effects of N-acetylcysteine and Buthionine Sulfoximine  

OpenAIRE

Abstract Background Multidrug resistance mediated by the multidrug resistance-associated protein 1 (MRP1) decreases cellular drug accumulation. The exact mechanism of MRP1 involved multidrug resistance has not been clarified yet, though glutathione (GSH) is likely to have a role for the resistance to occur. N-acetylcysteine (NAC) is a pro-glutathione drug. DL-Buthionine (S,R)-sulfoximine (BSO) is an inhibitor of GSH synthesis. The aim of our study was to investigate the effect of NAC and BSO ...

Savas Burhan; Akca Hakan; Akan Selma; Akan Ilhan; Ozben Tomris

2005-01-01

275

Biochemical Mechanism of Modulation of Human P-glycoprotein by Stemofoline  

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The resistance to chemotherapeutic drugs by cancer cells is considered to be one of the major obstacles for success in the treatment of cancer. A major mechanism underlying this multidrug resistance is the overexpression of P-glycoprotein (P-gp), resulting in an insufficient drug delivery to the tumor sites. A previous study has shown that stemofoline, an alkaloid isolated from Stemona burkillii could enhance the sensitivity of chemotherapeutics in a synergistic fashion. In the present study, we have focused on the effect of stemofoline on the modulation of P-gp function in a multidrug resistant human cervical carcinoma cell line (KB-V1). The effects of stemofoline on a radiolabeled drug, [3H]-vinblastine, and fluorescent P-gp substrates, rhodamine123, and, calcein-AM accumulation or retention were investigated to confirm this finding. Stemofoline could increase the accumulation or retention of radiolabeled drugs or fluorescent P-gp substrates in a dose-dependent manner. For additional studies on drug-P-gp binding, P-gp ATPase activity was stimulated by stemofoline in a concentration-dependent manner. More evidence was offered that stemofoline inhibits the effect on photoaffinity labeling of P-gp with the [125I]-iodoarylazidoprazosin in a concentration-dependent manner. These data indicate that stemofoline may interact directly with P-gp and inhibit P-gp activity, whereas stemofoline has no effect on P-gp expression. Taken together, the results exhibit that stemofoline possesses an effective MDR modulator, and may be used in combination with conventional chemotherapeutic drugs to reverse MDR in cancer cells. PMID:21786221

Chanmahasathien, Wisinee; Ohnuma, Shinobu; Ambudkar, Suresh V.; Limtrakul, Pornngarm

2013-01-01

276

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

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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.

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

277

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

International Nuclear Information System (INIS)

Highlights: ? The BCL2-inhibitor ABT-263 is a substrate for P-glycoprotein. ? Apoptosis is inhibited by P-glycoprotein expression. ? 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 3H 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.

278

Inhibition of P-glycoprotein-mediated Multidrug Resistance (MDR) by N,N-bis(cyclohexanol)amine aryl esters: further restriction of molecular flexibility maintains high potency and efficacy.  

Science.gov (United States)

Conformational modulation of the aryl portion of a set of N,N-bis(cyclohexanol)amine aryl esters (1a-d) that are potent Pgp-dependent MDR inhibitors has been performed. Toward this end the trans-3-(3,4,5-trimethoxyphenyl)acrylic acid present in set 1 was substituted with 3-(3,4,5-trimethoxyphenyl)propanoic and 3-(3,4,5-trimethoxyphenyl)propiolic moieties to give sets 2 and 3, respectively. While the introduction of 3-(3,4,5-trimethoxyphenyl)propanoic moiety resulted in a definite drop in potency and efficacy, esterification with 3-(3,4,5-trimethoxyphenyl)propiolic acid gave four isomers (3a-d) that maintain high potency and possess optimal efficacy. These results are discussed in terms of conformational flexibility of the different sets of compounds. PMID:21145739

Martelli, Cecilia; Dei, Silvia; Lambert, Catherine; Manetti, Dina; Orlandi, Francesca; Romanelli, Maria Novella; Scapecchi, Serena; Salerno, Milena; Teodori, Elisabetta

2011-01-01

279

Effects of chemically modified tetracyclines (CMTs) in sensitive, multidrug resistant and apoptosis resistant leukaemia cell lines.  

Science.gov (United States)

Recently discovered chemically modified tetracyclines (CMTs) have shown in vitro and in vivo anti-proliferative and anti-tumour activities. Here, we evaluated in vitro the anti-proliferative and apoptotic activity of six different dedimethylamino chemically modified tetracyclines (CMT-1, CMT-3, CMT-5, CMT-6, CMT-7 and CMT-8) in sensitive and multidrug resistant myeloid leukaemia cells (HL60 and HL60R) in vitro. Three of these compounds (CMT-5, CMT-6, CMT-7) showed low cytotoxic activity both in sensitive and in resistant cells, CMT-3 was endowed with a high anti-proliferative activity only in sensitive cells and was moderately effective as apoptosis inducing agent, with an activity similar to that shown by doxycycline. On the contrary, CMT-1 and CMT-8 were very effective as programmed cell death inducing agents. The apoptotic pathway activated by these compounds involved the activation of caspases, especially caspase-9 and, for CMT-1, also the activation of FAS: Interestingly CMT-8, but not CMT-1, was able to induce apoptosis in multidrug resistant HL60R and in Fas-ligand resistant HUT78B1 cell lines. These properties, together with others previously described (e.g. anti-metastatic and anti-osteolytic activities), suggest that CMT-8 may have important applications in the clinical management of cancer. The comparative analysis of structure-activity relationship of CMT-8 and doxycycline suggests that the C-5 hydroxy moiety may play an important role in conferring activity in multidrug resistant cells. These findings appear to support the hypothesis that CMT-8 may represent an interesting lead for the development of a new class of potent apoptosis inducer agents active in multidrug resistant and Fas-ligand resistant malignancies. PMID:11350867

Tolomeo, M; Grimaudo, S; Milano, S; La Rosa, M; Ferlazzo, V; Di Bella, G; Barbera, C; Simoni, D; D'Agostino, P; Cillari, E

2001-05-01

280

Higher Desolvation Energy Reduces Molecular Recognition in Multi-Drug Resistant HIV-1 Protease  

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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.

Ladislau C. Kovari

2012-05-01

281

Prevalence of Multidrug Resistant Mycobacterium tuberculosis by Mycobacteria growth  

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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

Livani S

2012-01-01

282

Nanodrugs: optimism for emerging trend of multidrug resistance  

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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-?-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.

Khan AU

2012-08-01

283

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)

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.

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

284

Multidrug resistance in fungi: regulation of transporter-encoding gene expression.  

Science.gov (United States)

A critical risk to the continued success of antifungal chemotherapy is the acquisition of resistance; a risk exacerbated by the few classes of effective antifungal drugs. Predictably, as the use of these drugs increases in the clinic, more resistant organisms can be isolated from patients. A particularly problematic form of drug resistance that routinely emerges in the major fungal pathogens is known as multidrug resistance. Multidrug resistance refers to the simultaneous acquisition of tolerance to a range of drugs via a limited or even single genetic change. This review will focus on recent progress in understanding pathways of multidrug resistance in fungi including those of most medical relevance. Analyses of multidrug resistance in Saccharomyces cerevisiae have provided the most detailed outline of multidrug resistance in a eukaryotic microorganism. Multidrug resistant isolates of S. cerevisiae typically result from changes in the activity of a pair of related transcription factors that in turn elicit overproduction of several target genes. Chief among these is the ATP-binding cassette (ABC)-encoding gene PDR5. Interestingly, in the medically important Candida species, very similar pathways are involved in acquisition of multidrug resistance. In both C. albicans and C. glabrata, changes in the activity of transcriptional activator proteins elicits overproduction of a protein closely related to S. cerevisiae Pdr5 called Cdr1. The major filamentous fungal pathogen, Aspergillus fumigatus, was previously thought to acquire resistance to azole compounds (the principal antifungal drug class) via alterations in the azole drug target-encoding gene cyp51A. More recent data indicate that pathways in addition to changes in the cyp51A gene are important determinants in A. fumigatus azole resistance. We will discuss findings that suggest azole resistance in A. fumigatus and Candida species may share more mechanistic similarities than previously thought. PMID:24795641

Paul, Sanjoy; Moye-Rowley, W Scott

2014-01-01

285

Multidrug Resistance in Fungi: Regulation of Transporter-encoding Gene Expression  

Directory of Open Access Journals (Sweden)

Full Text Available A critical risk to the continued success of antifungal chemotherapy is the acquisition of resistance; a risk exacerbated by the few classes of effective antifungal drugs. Predictably, as the use of these drugs increases in the clinic, more resistant organisms can be isolated from patients. A particularly problematic form of drug resistance that routinely emerges in the major fungal pathogens is known as multidrug resistance. Multidrug resistance refers to the simultaneous acquisition of tolerance to a range of drugs via a limited or even single genetic change. This review will focus on recent progress in understanding pathways of multidrug resistance in fungi including those of most medical relevance. Analyses of multidrug resistance in Saccharomyces cerevisiae have provided the most detailed outline of multidrug resistance in a eukaryotic microorganism. Multidrug resistant isolates of S. cerevisiae typically result from changes in the activity of a pair of related transcription factors that in turn elicit overproduction of several target genes. Chief among these is the ATP-binding cassette-encoding gene PDR5. Interestingly, in the medically important Candida species, very similar pathways are involved in acquisition of multidrug resistance. In both C. albicans and C. glabrata, changes in the activity of transcriptional activator proteins elicits overproduction of a protein closely related to S. cerevisiae Pdr5 called Cdr1. The major filamentous fungal pathogen, Aspergillus fumigatus, was previously thought to acquire resistance to azole compounds (the principal antifungal drug class via alterations in the azole drug target-encoding gene cyp51A. More recent data indicate that pathways in addition to changes in the cyp51A gene are important determinants in A. fumigatus azole resistance. We will discuss findings that suggest azole resistance in A. fumigatus and Candida species may share more mechanistic similarities than previously thought.

ScottMoye-Rowley

2014-04-01

286

Antimicrobial resistance determinant microarray for analysis of multi-drug resistant isolates  

Science.gov (United States)

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.

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

287

Efflux pump gene hefA of Helicobacter pylori plays an important role in multidrug resistance  

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Full Text Available AIM: To determine whether efflux systems contribute to multidrug resistance of H pylori.METHODS: A chloramphenicol-induced multidrug resistance model of six susceptible H pylori strains (5 isolates and H pylori NCTC11637 was developed. Multidrug-resistant (MDR strains were selected and the minimal inhibitory concentration (MIC of erythromycin, metronidazole, penicillin G, tetracycline, and ciprofloxacin in multidrug resistant strains and their parent strains was determined by agar dilution tests. The level of mRNA expression of hefA was assessed by fluorescence real-time quantitative PCR. A H pylori LZ1026 knockout mutant (?H pylori LZ1026 for (putative efflux protein was constructed by inserting the kanamycin resistance cassette from pEGFP-N2 into hefA, and its susceptibility profiles to 10 antibiotics were evaluated.RESULTS: The MIC of six multidrug-resistant strains (including 5 clinical isolates and H pylori NCTC11637 increased significantly (? 4-fold compared with their parent strains. The expression level of hefA gene was significantly higher in the MDR strains than in their parent strains (P = 0.033. A H pylori LZ1026 mutant was successfully constructed and the ?H pylori LZ1026 was more susceptible to four of the 10 antibiotics. All the 20 strains displayed transcripts for hefA that confirmed the in vitro expression of these genes.CONCLUSION: The efflux pump gene hefA plays an important role in multidrug resistance of H pylori.

Zhi-Qiang Liu, Peng-Yuan Zheng, Ping-Chang Yang

2008-09-01

288

Treatment of nosocomial meningitis due to a multidrug resistant Acinetobacter baumannii with intraventricular colistin.  

OpenAIRE

ABSTRACT We report a case of serious nosocomial meningitis due to a multidrug-resistant Acinetobacter baumannii in a 23-year-old woman who had a posterior fossa craniotomy with upper cervical laminectomy for excision of a meningioma at the level of foramen magnum. Post-operatively, she had neck pain with continuous fever and deterioration in the level of consciousness and convulsions. The CSF was turbid and had neutrophil pleocytosis. A multidrug-resistant Acinetobacter baumannii was isola...

Zakeya Bukhary; Wafeeq Mahmood; Ahmed Al-Khani; Al-abdely, Hail M.

2005-01-01

289

Influence of efflux pump inhibitors on the multidrug resistance of Helicobacter pylori  

OpenAIRE

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...

Zhan Zhang, Zhi-qiang Liu

2010-01-01

290

Acute-onset postoperative endophthalmitis caused by multidrug-resistant Klebsiella pneumoniae  

Science.gov (United States)

The purpose of this paper is to report outcomes of intravitreal imipenem in the treatment of multidrug-resistant Klebsiella-related postoperative endophthalmitis. This observational case series consists of three eyes from three patients seen between 2013 and 2014. Multidrug-resistant Klebsiella pneumoniae is characterized by a rapid, fulminant course and severe intraocular inflammation. Intravitreal imipenem may be used to treat such infection. PMID:25258505

Sanghi, Shekhar; Pathengay, Avinash; Jindal, Animesh; Raval, Vishal; Nayak, Sameera; Sharma, Savitri; Bawdekar, Abhishek; Flynn, Harry W

2014-01-01

291

Discovering Natural Product Modulators to Overcome Multidrug Resistance in Cancer Chemotherapy  

OpenAIRE

Multidrug resistance caused by the overexpression of ABC drug transporters is a major obstacle in clinical cancer chemotherapy. For several years, it appeared that direct inhibition of ABC transporters would be the cheapest and most efficient way to combat this problem. Unfortunately, progress in finding a potent, selective inhibitor to modulate ABC transporters and restore drug sensitivity in multidrug-resistant cancer cells has been slow and challenging. Candidate drugs should ideally be se...

Wu, Chung-pu; Ohnuma, Shinobu; Ambudkar, Suresh V.

2011-01-01

292

Modulation of multidrug resistance by flavonoids. Inhibitors of glutathione conjugation and MRP-mediated transport  

OpenAIRE

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...

Zanden, J. J.

2005-01-01

293

Technetium-99m-hexakis-2-methoxyisobutylisonitrile scintigraphy and multidrug resistance-related protein expression in human primary lung cancer  

International Nuclear Information System (INIS)

The occurrence of multidrug resistance (MDR) is a major cause of resistance to chemotherapeutic agents in patients with lung cancer, in part owing to the overexpression of MDR-related proteins. Technetium-99m-hexakis-2-methoxyisobutylisonitrile (99mTc-MIBI) has been shown to be a substrate for some MDR-related proteins. The aim of this study is to evaluate the role of 99mTc-MIBI scintigraphy for functional imaging of MDR-related protein phenotypes. To determine the correlation between 99mTc-MIBI scintigraphy and the expression level of P-glycoprotein (Pgp), multidrug-resistance protein (MRP), and glutathione-S-transferase Pi (GST?), 26 patients (17 men and 9 women, median age 57.5 years) with primary lung cancer were investigated. Following intravenous administration of 925 MBq 99mTc-MIBI, single-photon emission computed tomography (SPECT) and computed tomography (CT) were performed at 15 min and 2 h. On the basis of the fused images, tumor to background (T/B) ratio of both early and delayed images, and washout rate (WR%) of 99mTc-MIBI were calculated. The immunohistochemical staining of Pgp, MRP, and GST? was performed, and the expression level was semiquantitated using a pathoimage analysis system. The imaging results were compared with the status of Pgp, MRP, and GST? expression. The WR% of 99mTc-MIBI showed a significant positive correlation with Pgp expression (r=0.560, P=0.003), as no correlatiion (r=0.560, P=0.003), as no correlation was observed between WR% and MRP or GST? (r=0.354, P=0.076; r=0.324, P=0.106). Neither early T/B nor delayed T/B correlated with the expression level of Pgp, MRP, and GST?. WR%, Pgp, and GST? expression showed significant differences between squamous cell carcinoma (group A) and adenocarcinoma (group B). There was no significant difference among Pgp, MRP, and GST? expression levels in any cases (P>0.05). Our data confirmed that 99mTc-MIBI scintigraphy is useful for determining the MDR caused by Pgp in patients with primary lung cancer. (author)

294

Interindividual Variability in Hepatic Organic Anion-Transporting Polypeptides and P-Glycoprotein (ABCB1) Protein Expression: Quantification by Liquid Chromatography Tandem Mass Spectroscopy and Influence of Genotype, Age, and Sex  

OpenAIRE

Interindividual variability in protein expression of organic anion-transporting polypeptides (OATPs) OATP1B1, OATP1B3, OATP2B1, and multidrug resistance-linked P-glycoprotein (P-gp) or ABCB1 was quantified in frozen human livers (n = 64) and cryopreserved human hepatocytes (n = 12) by a validated liquid chromatography tandem mass spectroscopy (LC-MS/MS) method. Membrane isolation, sample workup, and LC-MS/MS analyses were as described before by our laboratory. Briefly, total native membrane p...

Prasad, Bhagwat; Evers, Raymond; Gupta, Anshul; Hop, Cornelis E. C. A.; Salphati, Laurent; Shukla, Suneet; Ambudkar, Suresh V.; Unadkat, Jashvant D.

2014-01-01

295

Photoaffinity labeling of P-glycoprotein.  

Science.gov (United States)

The aim of the present review is to summarize recent progress in identifying substrate binding domains of P-glycoprotein by photoaffinity labeling. Preferred substrate binding regions have been identified using a number of photoaffinity ligands, including anthracyclines, the quinazoline iodoarylazidoprazosine (IAAP), dihydropyridines, taxanes and propafenones. These studies allowed identification of protein regions, which are involved in ligand interaction. PMID:15720286

Peer, Michael; Csaszar, Edina; Vorlaufer, Elisabeth; Kopp, Stephan; Chiba, Peter

2005-02-01

296

Where is it and how does it get there – intracellular localization and traffic of P-glycoprotein  

Directory of Open Access Journals (Sweden)

Full Text Available P-glycoprotein (P-gp, an ATP-binding cassette (ABC, is able to transport structurally and chemically unrelated substrates. Overexpression of P-gp in cancer cells significantly decreases the intercellular amount of anticancer drugs, and results in multidrug resistance in cancer cells, a major obstacle in cancer chemotherapy. P-gp is mainly localized on the plasma membrane and functions as a drug efflux pump; however, P-gp is also localized in many intracellular compartments, such as endoplasmic reticulum, Golgi, endosomes and lysosomes. P-gp moves between the intracellular compartments and the plasma membrane in a microtubule-actin dependent manner. This review highlights our current understanding of 1 the intracellular localization of P-gp; 2 the trafficking and cycling pathways among the cellular compartments as well as between these compartments and the plasma membrane; and 3 the cellular factors regulating P-gp traffic and cycling. This review also presents a potential implication in overcoming P-gp-mediated multidrug resistance by targeting P-gp traffic and cycling pathways and impairing P-gp localization on the plasma membrane.

DongFu

2013-12-01

297

FZD1 activates protein kinase C delta-mediated drug-resistance in multidrug-resistant MES-SA/Dx5 cancer cells.  

Science.gov (United States)

Multidrug-resistant (MDR) cancer is a major clinical problem in chemotherapy of cancer patients. We have noted inappropriate PKC? hypomethylation and overexpression of genes in the PKC?/AP-1 pathway in the human uterus sarcoma drug-resistant cell line, MES-SA/Dx5 cells, which also overexpress p-glycoprotein (ABCB1). Recent studies have indicated that FZD1 is overexpressed in both multidrug-resistant cancer cell lines and in clinical tumor samples. These data have led us to hypothesize that the FZD1-mediated PKC? signal-transduction pathway may play an important role in drug resistance in MES-SA/Dx5 cells. In this work, the PKC? inhibitor Rottlerin was found to reduce ABCB1 expression and to inhibit the MDR drug pumping ability in the MES-SA/Dx5 cells when compared with the doxorubicin-sensitive parental cell line, MES-SA. PKC? was up-regulated with concurrent up-regulation of the mRNA levels of the AP-1-related factors, c-JUN and c-FOS. Activation of AP-1 also correlated with up-regulation of the AP-1 downstream genes HGF and EGR1. Furthermore, AP-1 activities were reduced and the AP-1 downstream genes were down-regulated in Rottlerin-treated or PKC? shRNA-transfected cells. MES-SA/Dx5 cells were resensitized to doxorubicin-induced toxicity by co-treatment with doxorubicin and Rottlerin or PKC? shRNA. In addition, cell viability and drug pump-out ability were significantly reduced in the FZD1 inhibitor curcumin-treated and FZD1 shRNA-knockdown MES-SA/Dx5 cells, indicating involvement of PKC? in FZD1-modulated ABCB1 expression pathway. Taken together, our data demonstrate that FZD1 regulates PKC?, and the PKC?/AP-1 signalling transduction pathway plays an important role in drug resistance in MES-SA/Dx5 cells. PMID:24814288

Hung, Tsai-Hsien; Chen, Chuan-Mu; Tseng, Ching-Ping; Shen, Chih-Jie; Wang, Hui-Ling; Choo, Kong-Bung; Chong, Kowit Yu

2014-08-01

298

The cytotoxic effect and the multidrug resistance reversing action of lignans from Phyllanthus amarus.  

Science.gov (United States)

Multidrug resistance (MDR) constitutes the major obstacle to the successful treatment of cancer. In several cancer cells, MDR is thought to be mediated by the super-expression of P-glycoprotein (Pgp). Pgp extrudes drugs from the cells, therefore reducing their cytotoxicity, and its activity inhibition may reverse the MDR phenotype. The present study evaluated the possible cytotoxic effect and MDR reversing properties of the extract and compounds isolated from Phyllanthus amarus. To this purpose, two human leukaemia cell lines were employed: K-562 and its vincristine-resistant counterpart Lucena-1, a Pgp-overexpressing subline. We report here that Lucena-1 was significantly more resistant to the cytotoxicity of P. amarus derivatives: the hexane extract (HE, 100 microg/mL), the lignans-rich fraction (LRF, 100 microg/mL) and the lignans nirtetralin (NIRT, 43.2 microg/mL), niranthin (NIRA, 43 microg/mL) or phyllanthin (PHYLLA, 43 microg/mL) exerted cytotoxic effects on K-562 cells with 40.3, 66.0, 62.0, 61.0 or 24.1% of cell death, respectively. The cellular toxicity observed on Lucena-1 was 16.3, 40.4, 29.4, 30.2, or 24.8%, respectively. However, cell treatment with the lignan phyltetralin (PHYLT) up to 41.6 microg/mL had no cytotoxic action on either of the cell lines. P. amarus derivatives were also found to be effective in inhibiting Pgp activity as assessed by rhodamine accumulation in Lucena-1 cells, as were the classical Pgp inhibitors, cyclosporine A (160 nM), PSC-833 (2 microM) and verapamil (5 microM). The lignan NIRT produced the most potent inhibition (EC (50) = 29.4 microg/mL) followed by NIRA (44.3 microg/mL), LRF (49.1 microg/mL), PHYLT (99.4 microg/mL), PHYLLA and HE (> 100 microg/mL). Lucena-1 cells were more resistant to daunorubicin-induced cell death (LC (50) = 50 microM) than K562 cells (LC (50) = 4.95 microM). Of note, the P. amarus derivatives significantly potentiated 5 microM daunorubicin-induced cell death in Lucena-1 cells (P < 0.01) but not in K562 cells. After treatment only with P. amarus derivatives (100 microg/mL HE, 30 microg/mL LRF, 12.9 microg/mL NIRA, 43.2 microg/mL NIRT, 43 microg/mL PHYLLA or 41.6 microg/mL PHYLT), the Lucena-1 cellular viability was 83.7, 85.3, 101, 69.7, 75.6 or 88.7%, respectively, whereas the in the presence of daunorubincin, which was not cytotoxic PER SE, the cell viability decreased to 42.9, 42.2, 64.2, 35.4, 30.4 or 52.6%, respectively. Together, these results suggest a potential action of P. amarus derivatives as MDR reversing agents, mainly due to their ability to synergize with the action of conventional chemotherapeutics. PMID:17054045

Leite, Daniela F; Kassuya, Cândida A; Mazzuco, Tânia L; Silvestre, Aline; de Melo, Lucilia V; Rehder, Vera L; Rumjanek, Vivian M; Calixto, João B

2006-12-01

299

Structure of P-Glycoprotein Reveals a Molecular Basis for Poly-Specific Drug Binding  

Energy Technology Data Exchange (ETDEWEB)

P-glycoprotein (P-gp) detoxifies cells by exporting hundreds of chemically unrelated toxins but has been implicated in multidrug resistance (MDR) in the treatment of cancers. Substrate promiscuity is a hallmark of P-gp activity, thus a structural description of poly-specific drug-binding is important for the rational design of anticancer drugs and MDR inhibitors. The x-ray structure of apo P-gp at 3.8 angstroms reveals an internal cavity of -6000 angstroms cubed with a 30 angstrom separation of the two nucleotide-binding domains. Two additional P-gp structures with cyclic peptide inhibitors demonstrate distinct drug-binding sites in the internal cavity capable of stereoselectivity that is based on hydrophobic and aromatic interactions. Apo and drug-bound P-gp structures have portals open to the cytoplasm and the inner leaflet of the lipid bilayer for drug entry. The inward-facing conformation represents an initial stage of the transport cycle that is competent for drug binding.

Aller, Stephen G.; Yu, Jodie; Ward, Andrew; Weng, Yue; Chittaboina, Srinivas; Zhuo, Rupeng; Harrell, Patina M.; Trinh, Yenphuong T.; Zhang, Qinghai; Urbatsch, Ina L.; Chang, Geoffrey; (Scripps); (TTU)

2009-04-22

300

Selenorhodamine photosensitizers for photodynamic therapy of P-glycoprotein-expressing cancer cells.  

Science.gov (United States)

We examined a series of selenorhodamines with amide and thioamide functionality at the 5-position of a 9-(2-thienyl) substituent on the selenorhodamine core for their potential as photosensitizers for photodynamic therapy (PDT) in P-glycoprotein (P-gp) expressing cells. These compounds were examined for their photophysical properties (absorption, fluorescence, and ability to generate singlet oxygen), for their uptake into Colo-26 cells in the absence or presence of verapamil, for their dark and phototoxicity toward Colo-26 cells, for their rates of transport in monolayers of multidrug-resistant, P-gp-overexpressing MDCKII-MDR1 cells, and for their colocalization with mitochondrial specific agents in Colo-26 cells. Thioamide derivatives 16b and 18b were more effective photosensitizers than amide derivatives 15b and 17b. Selenorhodamine thioamides 16b and 18b were useful in a combination therapy to treat Colo-26 cells in vitro: a synergistic therapeutic effect was observed when Colo-26 cells were exposed to PDT and treatment with the cancer drug doxorubicin. PMID:25250825

Hill, Jacqueline E; Linder, Michelle K; Davies, Kellie S; Sawada, Geri A; Morgan, Janet; Ohulchanskyy, Tymish Y; Detty, Michael R

2014-10-23

301

The network of P-glycoprotein and microRNAs interactions.  

Science.gov (United States)

Overexpression of P-glycoprotein (P-gp) contributes to the multidrug resistance (MDR) phenotype found in many cancer cells. P-gp has been identified as a promising molecular target, although attempts to find successful therapies to counteract its function as a drug efflux pump have largely failed to date. Apart from its role in drug efflux, P-gp may have other cellular functions such as being involved in apoptosis, and is found in various locations in the cell. Its expression is highly regulated, namely by microRNAs (miRNAs or miRs). In addition, P-gp may regulate the expression of miRs in the cell. Furthermore, both P-gp and miRs may be found in microvesicles or exosomes and may be transported to neighboring, drug-sensitive cells. Here, we review this current issue together with recent evidence of this network of interactions between P-gp and miRs. PMID:24122334

Lopes-Rodrigues, Vanessa; Seca, Hugo; Sousa, Diana; Sousa, Emília; Lima, Raquel T; Vasconcelos, M Helena

2014-07-15

302

Chemoprevention and inhibition of P-glycoprotein in cancer cells by Chinese medicinal herbs.  

Science.gov (United States)

Many of the herbal extracts used in the Chinese clinical medical routine inhibit the growth of tumor cells. In the present work, extracts of 12 selected herbs were prepared with methanol, chloroform, ethyl acetate and water, and the effects of these on the multidrug resistance (MDR) and P-glycoprotein of mouse lymphoma cells transfected with the human mdr1 gene and on a human lung alveolar epithelial cell line were investigated. The extracts were tested for antiproliferative effects, and the reversal of MDR in mouse lymphoma cells. The possible chemopreventive effect of the chloroform extracts was studied on the expression of cytomegalovirus (CMV) immediate-early (IE) antigen in human lung cancer cells (A549). The antimicrobial effects of the extracts were tested on some representative micro-organisms. Certain of the chloroform extracts of the plant materials were the most effective compounds on the reversal of MDR. Two of the chloroform extracts enhanced the antiproliferative effect of doxorubicin on MDR mouse lymphoma cells. The selected extracts did not show any antibacterial effect with the agar diffusion method. Certain chloroform extracts decreased the intermediate IE antigen expression of CMV in A459 cells. PMID:18690658

Engi, Helga; Hohmann, Judit; Gang, Geng; Pusztai, Rozália; Rédei, Dóra; Kovács, Orsolya; Schelz, Zsuzsanna; Molnár, Joseph

2008-12-01

303

Expression of multidrug resistance proteins, P-gp, MRP1 and LRP, in soft tissue sarcomas analysed according to their histological type and grade.  

Science.gov (United States)

The biological behaviour of different histological types and grades of soft tissue sarcomas (STS) varies. This might result in a differing sensitivity to cytotoxic drugs. Cross-resistance to functionally and structurally distinct natural-product drugs, known as multidrug resistance (MDR), is associated with the overexpression of P-glycoprotein (P-gp), multidrug resistance-associated protein 1 (MRP1) and lung resistance-related protein (LRP). The purpose of this study was to evaluate the expression of P-gp, MRP1 and LRP in STS according to their histological type and grade. In 141 chemotherapy-naive STS patients, the expression of the three MDR proteins was detected by immunohistochemistry. Nine histological types were documented. These were 19% grade 1, 34% grade 2 and 47% grade 3 tumours. Expression of P-gp and LRP was observed more frequently than the expression of MRP1 (PLRP was strongly expressed in MFH and unspecified sarcomas, but was low in liposarcomas. MRP1 and LRP expression was significantly more common in grades 2 and 3 compared with grade 1 tumours. P-gp expression was correlated with MRP1, especially in grade 3 STS. In conclusion, P-gp, MRP1 and LRP are expressed in the majority of STS, but this expression varies according to the histological type. MRP1 and LRP, but not P-gp expression, were found to be correlated to tumour grade. MDR might contribute to the observed differences in clinical behaviour within the heterogeneous group of STS. PMID:12706359

Komdeur, R; Plaat, B E C; van der Graaf, W T A; Hoekstra, H J; Hollema, H; van den Berg, E; Zwart, N; Scheper, R J; Molenaar, W M

2003-05-01

304

Identification of multi-drug resistance gene (MDR1) in equine ileum / Identificação do gene de resistência múltipla aos fármacos no íleo de eqüinos  

Scientific Electronic Library Online (English)

Full Text Available P-glicoproteína (P-gp) é uma membrana de transporte expressa pelo gene de resistência múltipla (MDR1), presente em diversos tecidos e normais e células tumorais. Embora o gene MDR1 e a P-gp já tenham sido identificados em diferentes espécies, ainda não se têm informações com relação à especie equina [...] . O gene MDR1 e a P-gp são capazes de interferir com a bioviabilidade e a disposição de diversos fármacos, alterando a farmacocinética e a farmacodinâmica dos mesmos. A presença do gene MDR1 e da P-gp no sistema nervoso central impede a entrada de certos fármacos neste tecido e, no trato gastrointestinal, eles reduzem a absorção de fármacos e aumentam sua eliminação. Neste estudo, comprovou-se pela primeira vez, a presença do gene MDR1 no íleo de eqüinos. Sugere-se que estudos futuros sejam realizados para a determinação do impacto da presença da P-glicoproteína nos efeitos de diversos fármacos em eqüinos. Abstract in english P-glycoprotein (P-gp) is a membrane transporter encoded in the Multi-drug Resistance (MDR1) gene expressed in several normal tissues and over expressed in tumor cells. P-gp was already identified in different species but not yet in equine. MDR1 gene and P-gp are able to interfere with bioavailabilit [...] y and disposition of several drugs, altering pharmacokinetic and pharmacodinamic of drugs. The presence of the MDR1 and P-gp in the central nervous system blocks the entry of certain drugs in this tissue and reduces drug absorption and enhances drug elimination when P-gp and MDR1 are presented in the gastrointestinal tract. This study showed that the MDR1 gene is present in equine ileum. Future studies on the impact of the P-glycoprotein encoded gene MDR1 on drugs pharmacologic effects in horses are granted.

Cláudio Corrêa, Natalini; Renata Lehn, Linardi.

2006-02-01

305

Multidrug-resistant tuberculosis among male inmates in Rio de Janeiro, Brazil  

OpenAIRE

Susceptibility tests to six anti-tuberculosis drugs were performed on fifty-eight M. tuberculosis isolates obtained from tuberculous inmates in the Male Penal Sanatorium, Rio de Janeiro, Brazil. The rate of resistant tuberculosis was higher than that observed in the community. The overall resistance rate was 17.2% and 3.4% of the isolates were multi-drug resistant.

Lourenço Maria Cristina da Silva; Silva Marlei Gomes da; Fonseca Leila de Souza

2000-01-01

306

Binding site(s) on P-glycoprotein for a newly synthesized photoaffinity analog of agosterol A.  

Science.gov (United States)

Agosterol A (AG-A) is a novel agent that reverses P-glycoprotein (P-gp) and multidrug resistance protein-1 (MRP1)-meditated multidrug resistance (MDR). We have synthesized [125I]11-azidophenyl agosterol A (azidoAG-A), a photoaffinity analog of AG-A, and characterized its binding to P-gp in membrane vesicles prepared from multidrug-resistant P-gp-overexpressing KB-C2 cells. The photoanalog photolabeled intact P-gp and both the N- and C-terminal fragments of P-gp. [125I]AzidoAG-A is transported by P-gp and the intracellular accumulation of both [125I]azidoAG-A and [3H]AG-A in KB-C2 cells was lower than that in the parental drug-sensitive KB-3-1 cells. [125I]AzidoAG-A bound to the drug binding site(s) on P-gp because photoaffinity labeling of P-gp was inhibited by a variety of known P-gp substrates, including anticancer, reversing, and anti-human immunodeficiency virus (HIV) agents. The binding of [125I]azidoAG-A to P-gp differs from the binding of other photolabeled probes such as iodoaryl-azidoprazosin (IAAP) to P-gp and from the binding of [125I]azidoAG-A to MRP1 based on the differing effects of flupentixol and glutathione (GSH) on their binding. Thus, [125I]azidoAG-A will be a useful tool to elucidate the structure and function of P-gp because it directly binds to the drug binding site(s) on P-gp, is transported by P-gp, and exhibits different P-gp binding characteristics than IAAP. PMID:14552590

Mitsuo, Masahiko; Noguchi, Tomohiro; Nakajima, Yuichi; Aoki, Shunji; Ren, Xiao-Qin; Sumizawa, Tomoyuki; Haraguchi, Misako; Kobayashi, Motomasa; Baba, Masanori; Nagata, Yukihiro; Akiyama, Shin-ichi; Furukawa, Tatsuhiko

2003-01-01

307

Emergence of fluoroquinolones-resistant strains of Salmonella typhi: Watch on multidrug-resistant isolates  

Directory of Open Access Journals (Sweden)

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.

Subhash C Arya

2010-05-01

308

Multidrug-resistant nontuberculous mycobacteria isolated from cystic fibrosis patients.  

Science.gov (United States)

Worldwide, nontuberculous mycobacteria (NTM) have become emergent pathogens of pulmonary infections in cystic fibrosis (CF) patients, with an estimated prevalence ranging from 5 to 20%. This work investigated the presence of NTM in sputum samples of 129 CF patients (2 to 18 years old) submitted to longitudinal clinical supervision at a regional reference center in Rio de Janeiro, Brazil. From June 2009 to March 2012, 36 NTM isolates recovered from 10 (7.75%) out of 129 children were obtained. Molecular identification of NTM was performed by using PCR restriction analysis targeting the hsp65 gene (PRA-hsp65) and sequencing of the rpoB gene, and susceptibility tests were performed that followed Clinical and Laboratory Standards Institute recommendations. For evaluating the genotypic diversity, pulsed-field gel electrophoresis (PFGE) and/or enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR) was performed. The species identified were Mycobacterium abscessus subsp. bolletii (n = 24), M. abscessus subsp. abscessus (n = 6), Mycobacterium fortuitum (n = 3), Mycobacterium marseillense (n = 2), and Mycobacterium timonense (n = 1). Most of the isolates presented resistance to five or more of the antimicrobials tested. Typing profiles were mainly patient specific. The PFGE profiles indicated the presence of two clonal groups for M. abscessus subsp. abscessus and five clonal groups for M. abscesssus subsp. bolletii, with just one clone detected in two patients. Given the observed multidrug resistance patterns and the possibility of transmission between patients, we suggest the implementation of continuous and routine investigation of NTM infection or colonization in CF patients, including countries with a high burden of tuberculosis disease. PMID:24920766

Cândido, Pedro Henrique Campanini; Nunes, Luciana de Souza; Marques, Elizabeth Andrade; Folescu, Tânia Wrobel; Coelho, Fábrice Santana; de Moura, Vinicius Calado Nogueira; da Silva, Marlei Gomes; Gomes, Karen Machado; Lourenço, Maria Cristina da Silva; Aguiar, Fábio Silva; Chitolina, Fernanda; Armstrong, Derek T; Leão, Sylvia Cardoso; Neves, Felipe Piedade Gonçalves; Mello, Fernanda Carvalho de Queiroz; Duarte, Rafael Silva

2014-08-01

309

Genetic Diversity of Multidrug-Resistant Mycobacterium tuberculosis Isolates and Identification of 11 Novel rpoB Alleles in Taiwan  

OpenAIRE

Of 162 multidrug-resistant Mycobacterium tuberculosis isolates from Taiwan, 60.5% were found to belong to the Beijing family on the basis of spoligotyping results. IS6110 restriction fragment length polymorphism fingerprinting showed genetic diversity among the multidrug-resistant isolates. Furthermore, 90.1% of the multidrug-resistant isolates had mutations in the rpoB gene, and 11 novel alleles were recognized.

Jou, Ruwen; Chen, Huang-yau; Chiang, Chen-yuan; Yu, Ming-chih; Su, Ih-jen

2005-01-01

310

Multifunctional polyamidoamine-modified selenium nanoparticles dual-delivering siRNA and cisplatin to A549/DDP cells for reversal multidrug resistance.  

Science.gov (United States)

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. PMID:25204523

Zheng, Wenjing; Cao, Chengwen; Liu, Yanan; Yu, Qianqian; Zheng, Chuping; Sun, Dongdong; Ren, Xiaofan; Liu, Jie

2015-01-01

311

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

Science.gov (United States)

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. PMID:25486495

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

2015-01-01

312

Overview of P-glycoprotein inhibitors: a rational outlook  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Glicoproteína-p (P-gp), uma glicoproteína de transmembrana permeável, é um membro da superfamília (ABC) de cassete de gene de ligação de ATP que funciona especificamente como um carreador mediado pelo transportador de efluxo ativo primário. É amplamente distribuído por todo o corpo e apresenta uma g [...] ama diversificada de substratos. Diversos agentes terapêuticos vitais são substratos para P-gp e sua biodisponibilidade é reduzida ou a resistência é induzida devido ao efluxo de proteínas. Portanto, os inibidores da P-gp foram explorados para a superação da resistência a múltiplas drogas e problemas de biodisponibilidade deficiente dos substratos terapêuticos da P-gp. A sensibilidade das moléculas da droga à P-gp e vice-versa, pode ser estabelecida por vários modelos experimentais in silico, in vitro e in vivo. Desde a descoberta da P-gp, diversas pesquisas identificaram várias estruturas químicas como inibidores da P-gp. O objetivo deste presente estudo foi o de enfatizar a descoberta e desenvolvimento de inibidores mais novos, inertes, atóxicos e mais eficazes, visando especificamente os da P-gp, como aqueles entre os extratos vegetais, excipientes e formulações farmacêuticas, e outras moléculas racionais de droga. As aplicações do conhecimento de biologia celular e molecular, bancos de dados estruturais in silico, estudos de modelagem molecular e análises da relação quantitativa estrutura-atividade (QSAR) no desenvolvimento de novos inibidores racionais da P-gp também foram mencionados. Abstract in english P-glycoprotein (P-gp), a transmembrane permeability glycoprotein, is a member of ATP binding cassette (ABC) super family that functions specifically as a carrier mediated primary active efflux transporter. It is widely distributed throughout the body and has a diverse range of substrates. Several vi [...] tal therapeutic agents are substrates to P-gp and their bioavailability is lowered or a resistance is induced because of the protein efflux. Hence P-gp inhibitors were explored for overcoming multidrug resistance and poor bioavailability problems of the therapeutic P-gp substrates. The sensitivity of drug moieties to P-gp and vice versa can be established by various experimental models in silico, in vitro and in vivo. Ever since the discovery of P-gp, the research plethora identified several chemical structures as P-gp inhibitors. The aim of this review was to emphasize on the discovery and development of newer, inert, non-toxic, and more efficient, specifically targeting P-gp inhibitors, like those among the natural herb extracts, pharmaceutical excipients and formulations, and other rational drug moieties. The applications of cellular and molecular biology knowledge, in silico designed structural databases, molecular modeling studies and quantitative structure-activity relationship (QSAR) analyses in the development of novel rational P-gp inhibitors have also been mentioned.

Kale Mohana Raghava, Srivalli; P. K., Lakshmi.

2012-09-01

313

A mechanism for P-glycoprotein-mediated apoptosis as revealed by verapamil hypersensitivity.  

Science.gov (United States)

Selection of tumor cell lines with anticancer drugs has led to the appearance of multidrug-resistant (MDR) subclones with P-glycoprotein 1 (P-gp1) expression. These cells are cross-resistant to several structurally and functionally dissimilar drugs. Interestingly, in the process of gaining resistance, MDR cells become hypersensitive or collaterally sensitive to membrane-active agents, such as calcium channel blockers, steroids, and local anaesthetics. In this report, hypersensitivity to the calcium channel blocker, verapamil, was analyzed in sensitive and resistant CHO cell lines. Our results show that treatment with verapamil preferentially induced apoptosis in MDR cells compared to drug-sensitive cells. This effect was independent of p53 activity and could be inhibited by overexpression of the Bcl-2 gene. The induction of apoptosis by verapamil had a biphasic trend in which maximum cell death occurred at 10 microM, followed by improved cell survival at higher concentrations (50 microM). We correlated this effect to a similar biphasic trend in P-gp1 ATPase activation by verapamil in which low concentrations of verapamil (10 microM) activated ATPase, followed by inhibition at higher concentrations. To confirm the relationship between apoptosis and ATPase activity, we used two inhibitors of P-gp1 ATPase, PSC 833 and ivermectin. These ATPase inhibitors reduced hypersensitivity to verapamil in MDR cells. In addition, low concentrations of verapamil resulted in the production of reactive oxygen species (ROS) in MDR cells. Taken together, these results show that apoptosis was preferentially induced by P-gp1 expressing cells exposed to verapamil, an effect that was mediated by ROS, produced in response the high ATP demand by P-gp1. PMID:14567677

Karwatsky, Joel; Lincoln, Maximilian C; Georges, Elias

2003-10-28

314

Conservation of the multidrug resistance efflux gene oprM in Pseudomonas aeruginosa.  

OpenAIRE

An intragenic probe derived from the multidrug resistance gene oprM hybridized with genomic DNA from all 20 serotypes of Pseudomonas aeruginosa and from all 34 environmental and clinical isolates tested, indicating that the MexA-MexB-OprM multidrug efflux system is highly conserved in this organism. The oprM probe also hybridized with genomic DNA from Pseudomonas aureofaciens, Pseudomonas chlororaphis, Pseudomonas syringae, Burkholderia pseudomallei, and Pseudomonas putida, suggesting that ef...

Bianco, N.; Neshat, S.; Poole, K.

1997-01-01

315

Immunoliposomal delivery of doxorubicin can overcome multidrug resistance mechanisms in EGFR-overexpressing tumor cells.  

Science.gov (United States)

Immunoliposomes (ILs) can be constructed to target the epidermal growth factor receptor (EGFR) to provide efficient intracellular drug delivery in tumor cells. We hypothesized that this approach might be able to overcome drug resistance mechanisms, which remain an important obstacle to better outcomes in cancer therapy. ILs were evaluated in vitro and in vivo against EGFR-overexpressing pairs of human cancer cells (HT-29 and MDA-MB-231) that either lack or feature the multidrug resistance (mdr) phenotype. In multidrug-resistant cell lines, ILs loaded with doxorubicin (DOX) produced 19-216-fold greater cytotoxicity than free DOX, whereas in nonresistant cells, immunoliposomal cytotoxicity of DOX was comparable with that of the free drug. In intracellular distribution studies, free DOX was efficiently pumped out of the multidrug-resistant tumor cells, whereas immunoliposomal DOX leads to 3.5-8 times higher accumulation of DOX in the cytoplasm and 3.5-4.9 times in the nuclei compared with the free drug. Finally, in vivo studies in the MDA-MB-231 Vb100 xenograft model confirmed the ability of anti-EGFR ILs-DOX to efficiently target multidrug-resistant cells and showed impressive antitumor effects, clearly superior to all other treatments. In conclusion, ILs provide efficient and targeted drug delivery to EGFR-overexpressing tumor cells and are capable of completely reversing the multidrug-resistant phenotype of human cancer cells. PMID:22519893

Mamot, Christoph; Ritschard, Reto; Wicki, Andreas; Küng, Willy; Schuller, Jan; Herrmann, Richard; Rochlitz, Christoph

2012-06-01

316

Multidrug resistance 1 gene polymorphisms may determine Crohn's disease behavior in patients from Rio de Janeiro  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english 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-microbiota interactions and in mediating fibrosis. Understanding the effects of several drugs associated with multidrug resistance 1 gene variants may aid in the selection of customized therapeutic regimens.

Ana Teresa P., Carvalho; Renata S.B., Fróes; Barbara C., Esberard; Juliana C.V.C., Santos; Davy C. M., Rapozo; Ana B., Grinman; Tatiana A., Simão; Pedro, Nicolau Neto; Ronir R., Luiz; Antonio José V., Carneiro; Heitor S.P. de, Souza; Luis Felipe, Ribeiro-Pinto.

317

Role of FKS Mutations in Candida glabrata: MIC values, echinocandin resistance, and multidrug resistance.  

Science.gov (United States)

Candida glabrata is the second leading cause of candidemia in U.S. hospitals. Current guidelines suggest that an echinocandin be used as the primary therapy for the treatment of C. glabrata disease due to the high rate of resistance to fluconazole. Recent case reports indicate that C. glabrata resistance to echinocandins may be increasing. We performed susceptibility testing on 1,380 isolates of C. glabrata collected between 2008 and 2013 from four U.S. cities, Atlanta, Baltimore, Knoxville, and Portland. Our analysis showed that 3.1%, 3.3%, and 3.6% of the isolates were resistant to anidulafungin, caspofungin, and micafungin, respectively. We screened 1,032 of these isolates, including all 77 that had either a resistant or intermediate MIC value with respect to at least one echinocandin, for mutations in the hot spot regions of FKS1 and FKS2, the major mechanism of echinocandin resistance. Fifty-one isolates were identified with hot spot mutations, 16 in FKS1 and 35 in FKS2. All of the isolates with an FKS mutation except one were resistant to at least one echinocandin by susceptibility testing. Of the isolates resistant to at least one echinocandin, 36% were also resistant to fluconazole. Echinocandin resistance among U.S. C. glabrata isolates is a concern, especially in light of the fact that one-third of those isolates may be multidrug resistant. Further monitoring of U.S. C. glabrata isolates for echinocandin resistance is warranted. PMID:24890592

Pham, Cau D; Iqbal, Naureen; Bolden, Carol B; Kuykendall, Randall J; Harrison, Lee H; Farley, Monica M; Schaffner, William; Beldavs, Zintars G; Chiller, Tom M; Park, Benjamin J; Cleveland, Angela A; Lockhart, Shawn R

2014-08-01

318

Expression of the human multidrug transporter in insect cells by a recombinant baculovirus  

International Nuclear Information System (INIS)

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 [3H]azidopine, presumably at the same two sites as the native protein. Various drugs and reversing agents compete with the [3H]azidopine binding reaction when added in excess, indicating that the recombinant human multidrug transporter exrecombinant human multidrug transporter expressed in insect cells is functionally similar to its authentic counterpart

319

Radiation- and chemoinduced multidrug resistance in colon carcinoma cells  

International Nuclear Information System (INIS)

Background and purpose: radiation can induce multidrug resistance (MDR) and thus interfere with simultaneous or subsequent chemotherapy. In SW620 colon carcinoma cells, the interrelation of various biological endpoints of MDR was analyzed and the potential of fractionated irradiation and chemoselection to evoke MDR was compared. Material and methods: to induce/select an MDR phenotype, SW620 were exposed to either 27 Gy in 1.8-Gy daily fractions or to 50% inhibiting concentrations of doxorubicin or cisplatin, given over 6-15 weeks. Expression of genes involved in MDR, including glutathione metabolism, was determined by semiquantitative RT-PCR (reverse transcription-polymerase chain reaction). Efflux was analyzed by flow cytometry after staining with rhodamine-123 or 5-chloromethyl fluorescein diacetate. Apoptosis was monitored after pulse exposure to doxorubicin or cisplatin. Colony-forming assays were performed under continuous drug exposure. Results: a pronounced gene induction was found in MRP2 after cisplatin selection and up to 3 weeks after radiation. LRP was activated only shortly after radiation. Radiation enhanced rhodamine-123 efflux to a similar extent as short-term chemoselection but not as much as long-term drug exposure. Drug-induced apoptosis was slightly delayed in preirradiated cells. Clonogenic growth in the progeny of irradiated cells was less sensitive to cisplatin but not to doxorubicin. Conclusion: fractionated radiation can induce an MDR phenotypnated radiation can induce an MDR phenotype in SW620. However, long-term drug exposure establishes a more efficient selection. Various endpoints are not fully concordant regarding the extent of MDR. Posttranscriptional modifications, pleiotropic regulation, and alternative pathways may cause these discrepancies. (orig.)

320

Activating PKC-?1 at the blood–brain barrier reverses induction of P-glycoprotein activity by dioxin and restores drug delivery to the CNS  

OpenAIRE

Upregulation of blood–brain barrier (BBB) P-glycoprotein expression causes central nervous system (CNS) pharmacoresistance. However, activation of BBB protein kinase C-?1 (PKC-?1) rapidly reduces basal P-glycoprotein transport activity. We tested whether PKC-?1 activation would reverse CNS drug resistance caused by dioxin acting through aryl hydrocarbon receptor. A selective PKC-?1 agonist abolished the increase in P-glycoprotein activity induced by dioxin in isolated rat brain capillar...

Wang, Xueqian; Hawkins, Brian T.; Miller, David S.

2011-01-01

321

Predicting P-glycoprotein-mediated drug transport based on support vector machine and three-dimensional crystal structure of P-glycoprotein.  

Science.gov (United States)

Human P-glycoprotein (P-gp) is an ATP-binding cassette multidrug transporter that confers resistance to a wide range of chemotherapeutic agents in cancer cells by active efflux of the drugs from cells. P-gp also plays a key role in limiting oral absorption and brain penetration and in facilitating biliary and renal elimination of structurally diverse drugs. Thus, identification of drugs or new molecular entities to be P-gp substrates is of vital importance for predicting the pharmacokinetics, efficacy, safety, or tissue levels of drugs or drug candidates. At present, publicly available, reliable in silico models predicting P-gp substrates are scarce. In this study, a support vector machine (SVM) method was developed to predict P-gp substrates and P-gp-substrate interactions, based on a training data set of 197 known P-gp substrates and non-substrates collected from the literature. We showed that the SVM method had a prediction accuracy of approximately 80% on an independent external validation data set of 32 compounds. A homology model of human P-gp based on the X-ray structure of mouse P-gp as a template has been constructed. We showed that molecular docking to the P-gp structures successfully predicted the geometry of P-gp-ligand complexes. Our SVM prediction and the molecular docking methods have been integrated into a free web server (http://pgp.althotas.com), which allows the users to predict whether a given compound is a P-gp substrate and how it binds to and interacts with P-gp. Utilization of such a web server may prove valuable for both rational drug design and screening. PMID:21991360

Bikadi, Zsolt; Hazai, Istvan; Malik, David; Jemnitz, Katalin; Veres, Zsuzsa; Hari, Peter; Ni, Zhanglin; Loo, Tip W; Clarke, David M; Hazai, Eszter; Mao, Qingcheng

2011-01-01

322

Pre-Multidrug-Resistant Mycobacterium tuberculosis Beijing Strain Associated with Disseminated Tuberculosis in a Pet Dog  

OpenAIRE

Resistance to isoniazid, ethambutol, and streptomycin was detected in a Mycobacterium tuberculosis strain, belonging to the Beijing family lineage, isolated from two nodule exudates of a Yorkshire terrier with generalized tuberculosis. This report alerts medical practitioners to the risk of dissemination of pre-multidrug-resistant tuberculosis (preMDR-TB) through exposure to M. tuberculosis-shedding pets.

Botelho, Ana; Perdiga?o, Joa?o; Canto, Ana; Albuquerque, Teresa; Leal, Nuno; Macedo, Rita; Portugal, Isabel; Cunha, Mo?nica V.

2014-01-01

323

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)

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 loaded with ADM or Tet can enhance the effective accumulation of the drugs in K562/A02. We propose that Fe3O4-MNPs loaded with ADM and Tet probably have synergetic effect on reversal in multidrug resistance.Keywords: magnetic nanoparticles, tetrandrine, adriamycin, multidrug resistance reversal, leukemia K562/A02

Baoan Chen

2008-06-01

324

Rapid detection of multidrug-resistant Mycobacterium tuberculosis using the malachite green decolourisation assay  

OpenAIRE

Early detection of drug resistance in Mycobacterium tuberculosis isolates allows for earlier and more effective treatment of patients. The aim of this study was to investigate the performance of the malachite green decolourisation assay (MGDA) in detecting isoniazid (INH) and rifampicin (RIF) resistance in M. tuberculosis clinical isolates. Fifty M. tuberculosis isolates, including 19 multidrug-resistant, eight INH-resistant and 23 INH and RIF-susceptible samples, were teste...

Coban, Ahmet Yilmaz; Uzun, Meltem

2013-01-01

325

Contribution of Efflux to the Emergence of Isoniazid and Multidrug Resistance in Mycobacterium tuberculosis  

OpenAIRE

Multidrug resistant (MDR) tuberculosis is caused by Mycobacterium tuberculosis resistant to isoniazid and rifampicin, the two most effective drugs used in tuberculosis therapy. Here, we investigated the mechanism by which resistance towards isoniazid develops and how overexpression of efflux pumps favors accumulation of mutations in isoniazid targets, thus establishing a MDR phenotype. The study was based on the in vitro induction of an isoniazid resistant phenotype by prolonged serial exposu...

Machado, Diana; Couto, Isabel; Perdiga?o, Joa?o; Rodrigues, Liliana; Portugal, Isabel; Baptista, Pedro; Veigas, Bruno; Amaral, Leonard; Viveiros, Miguel

2012-01-01

326

Primary resistance, multidrug resistance, and cross-resistance pathways in HBV as a consequence of treatment failure.  

Science.gov (United States)

Antiviral resistance is now the single most important factor in treatment failure using nucleos(t)ide analogues (NA). Primary drug resistance mutations refer to amino acid change(s) that result in reduced susceptibility to an antiviral agent. Secondary compensatory mutations restore replication defects associated with primary drug resistance and may be associated with low level reduced susceptibility. Several evolutionary pathways of drug resistant HBV have been observed in patients treated with NAs. It is possible that the drug resistance mutations selected with one agent may affect the efficacy of other NAs. Several major HBV-evolutionary NA-resistance pathways (rtM204I/V, rtN236T and rtA181T/V) have now been characterised. The rtM204V/I pathway is responsible for resistance to the L: -nucleosides, such as lamivudine (LMV), telbivudine (LdT) and clevudine (CLD), and also entecavir (ETV), whilst the rtN236T pathway is responsible for adefovir (ADV) and tenofovir (TFV) resistance. Both pathways are associated with clusters of secondary mutations that can affect subsequent treatment with NAs (rtT184G, rtS202I) such as ETV. The third pathway, rtA181T/V, is associated with resistance to LMV and ADV and is a potential multi-drug resistance pathway and will probably have an impact on TFV sensitivity, either alone or with the rtN236T. In naïve patients treated with ETV, atleast three mutations arising at the same time are required: rtL180M + rtM204V plus either one of rtT184, rtS202 or rtM250 codon changes. Finally, in highly drug-experienced patients, clusters of mutations such as rtA181T/I233V/N236T/M250L, all on the one dominant HBV genome, are being detected which are associated with multi-drug resistance. Sequential treatment with nucleos(t)ide analogue reverse transcriptase inhibitors (NRTI) promotes multidrug resistance. It is likely, therefore, that development of multi-drug resistance could be reduced by combination therapy optimised to individual viral phenotypes. PMID:19669299

Locarnini, Stephen

2008-06-01

327

Multidrug Resistant Salmonella typhi in Asymptomatic Typhoid Carriers among Food Handlers in Namakkal District, Tamil Nadu  

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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.

Senthilkumar B

2005-01-01

328

Tailoring Cytotoxicity of Antimicrobial Peptidomimetics with High Activity against Multidrug-Resistant Escherichia coli  

DEFF Research Database (Denmark)

Infections with multidrug-resistant pathogens are an increasing concern for public health. Recently, subtypes of peptide-peptoid hybrids were demonstrated to display potent activity against multidrug-resistant Gram-negative bacteria. Here, structural variation of these antibacterial peptidomimetics was investigated as a tool for optimizing cell selectivity. A protocol based on dimeric building blocks allowed for efficient synthesis of an array of peptide-peptoid oligomers representing length variation as well as different backbone designs displaying chiral or achiral peptoid residues. Lack of ?-chirality in the side chains of the peptoid residues proved to be correlated to reduced cytotoxicity. Furthermore, optimization of the length of these peptidomimetics with an alternating cationic-hydrophobic design was a powerful tool to enhance the selectivity against Gram-negative pathogens over benign mammalian cells. Thus, lead compounds with a high selectivity toward killing of clinically important multidrug-resistant E. coli were identified.

Jahnsen, Rasmus D; Sandberg-Schaal, Anne

2014-01-01

329

Additional Drug Resistance in Mycobacterium tuberculosis Isolates From Resected Cavities Among Patients With Multidrug-Resistant or Extensively Drug-Resistant Pulmonary Tuberculosis  

OpenAIRE

The pathogenesis of increasing drug resistance among patients with multidrug-resistant or extensively drug-resistant tuberculosis undergoing treatment is poorly understood. Increasing drug resistance found among Mycobacterium tuberculosis recovered from cavitary isolates compared with paired sputum isolates suggests pulmonary cavities may play a role in the development of worsening tuberculosis drug resistance.

Kempker, Russell R.; Rabin, Alexander S.; Nikolaishvili, Ketino; Kalandadze, Iagor; Gogishvili, Shota; Blumberg, Henry M.; Vashakidze, Sergo

2011-01-01

330

Role of p-glycoprotein in refractoriness of seizures to antiepileptic drugs in lennox-gastaut syndrome.  

Science.gov (United States)

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 epilepsies (P epilepsies (P = 0.001) and healthy controls (P = 0.002). These findings may explain seizure refractoriness to anti-epileptic drugs in Lennox-Gastaut syndome. PMID:24762861

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

2015-02-01

331

Shornephine A: structure, chemical stability, and P-glycoprotein inhibitory properties of a rare diketomorpholine from an Australian marine-derived Aspergillus sp.  

Science.gov (United States)

Chemical analysis of an Australian marine sediment-derived Aspergillus sp. (CMB-M081F) yielded the new diketomorpholine (DKM) shornephine A (1) together with two known and one new diketopiperazine (DKP), 15b-?-hydroxy-5-N-acetyladreemin (2), 5-N-acetyladreemin (3), and 15b-?-methoxy-5-N-acetyladreemin (4), respectively. Structure elucidation of 1-4 was achieved by detailed spectroscopic analysis, supported by chemical degradation and derivatization, and biosynthetic considerations. The DKM (1) underwent a facile (auto) acid-mediated methanolysis to yield seco-shornephine A methyl ester (1a). Our mechanistic explanation of this transformation prompted us to demonstrate that the acid-labile and solvolytically unstable DKM scaffold can be stabilized by N-alkylation. Furthermore, we demonstrate that at 20 ?M shornephine A (1) is a noncytotoxic inhibitor of P-glycoprotein-mediated drug efflux in multidrug-resistant human colon cancer cells. PMID:25158286

Khalil, Zeinab G; Huang, Xiao-cong; Raju, Ritesh; Piggott, Andrew M; Capon, Robert J

2014-09-19

332

Differential chemosensitization of P-glycoprotein overexpressing K562/Adr cells by withaferin A and Siamois polyphenols  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Multidrug resistance (MDR is a major obstacle in cancer treatment and is often the result of overexpression of the drug efflux protein, P-glycoprotein (P-gp, as a consequence of hyperactivation of NF?B, AP1 and Nrf2 transcription factors. In addition to effluxing chemotherapeutic drugs, P-gp also plays a specific role in blocking caspase-dependent apoptotic pathways. One feature that cytotoxic treatments of cancer have in common is activation of the transcription factor NF?B, which regulates inflammation, cell survival and P-gp expression and suppresses the apoptotic potential of chemotherapeutic agents. As such, NF?B inhibitors may promote apoptosis in cancer cells and could be used to overcome resistance to chemotherapeutic agents. Results Although the natural withanolide withaferin A and polyphenol quercetin, show comparable inhibition of NF?B target genes (involved in inflammation, angiogenesis, cell cycle, metastasis, anti-apoptosis and multidrug resistance in doxorubicin-sensitive K562 and -resistant K562/Adr cells, only withaferin A can overcome attenuated caspase activation and apoptosis in K562/Adr cells, whereas quercetin-dependent caspase activation and apoptosis is delayed only. Interestingly, although withaferin A and quercetin treatments both decrease intracellular protein levels of Bcl2, Bim and P-Bad, only withaferin A decreases protein levels of cytoskeletal tubulin, concomitantly with potent PARP cleavage, caspase 3 activation and apoptosis, at least in part via a direct thiol oxidation mechanism. Conclusions This demonstrates that different classes of natural NF?B inhibitors can show different chemosensitizing effects in P-gp overexpressing cancer cells with impaired caspase activation and attenuated apoptosis.

Gerlo Sarah

2010-05-01

333

Reversal of P-gp and MRP1-mediated multidrug resistance by H6, a gypenoside aglycon from Gynostemma pentaphyllum, in vincristine-resistant human oral cancer (KB/VCR) cells.  

Science.gov (United States)

Multidrug resistance (MDR) to anticancer drugs is a major obstacle to successful chemotherapy in the treatment of cancers. Identification of natural compounds capable of circumventing MDR with minimal adverse side effects is an attractive goal. Here, we found that H6, a gypenoside aglycon from Gynostemma pentaphyllum, displayed potent anti-MDR activity. Average resistant fold (RF) of H6 is 1.03 and 1.04 in KB/VCR and MCF-7/ADR cells compared to their parental cells. H6 alone ranging from 2 ?mol/l to 40 ?mol/l (?M) did not display a significant anti-proliferative effect on KB/VCR cells and other cells, while the compound at these concentrations enhanced the cytotoxicity of vincristine (VCR) to KB/VCR cells. H6 showed a significant synergistic effect in combination with VCR. By quantification of sub-G(1) fraction cells, H6 also enhanced the VCR-induced apoptosis in a dose-dependent manner. The short time treatment with H6 increased the intracellular accumulation of rhodamine 123 (Rho123) and 5(6)-carboxyfluorescein diacetate (CFDA) in KB/VCR cells. Further studies showed that H6 treatment resulted in the decrease of the RNA transcript level of P-glycoprotein (P-gp), multidrug resistance-associated protein 1 (MRP1) and breast cancer resistance protein (BCRP). H6 inhibited the function of P-gp by stimulating P-gp ATPase activity and decreased MRP1 expression with a blockade of STAT3 phosphorylation. These findings suggest that H6, a multi-targets reversal agent with no significant toxic effect, may be a potential candidate to circumvent the P-gp and MRP1-mediated MDR. PMID:23051672

Zhu, Hengrui; Liu, Zulong; Tang, Lisha; Liu, Junhua; Zhou, Mei; Xie, Fang; Wang, Zheng; Wang, Yuqi; Shen, Sida; Hu, Lihong; Yu, Long

2012-12-01

334

Cytosolic superoxide dismutase activity after photodynamic therapy, intracellular distribution of Photofrin II and hypericin, and P-glycoprotein localization in human colon adenocarcinoma.  

Directory of Open Access Journals (Sweden)

Full Text Available In photodynamic therapy (PDT, a tumor-selective photosensitizer is administered and then activated by exposure to a light source of applicable wavelength. Multidrug resistance (MDR is largely caused by the efflux of therapeutics from the tumor cell by means of P-glycoprotein (P-gp, resulting in reduced efficacy of the anticancer therapy. This study deals with photodynamic therapy with Photofrin II (Ph II and hypericin (Hyp on sensitive and doxorubicin-resistant colon cancer cell lines. Changes in cytosolic superoxide dismutase (SOD1 activity after PDT and the intracellular accumulation of photosensitizers in sensitive and resistant colon cancer cell lines were examined. The photosensitizers' distributions indicate that Ph II could be a potential substrate for P-gp, in contrast to Hyp. We observed an increase in SOD1 activity after PDT for both photosensitizing agents. The changes in SOD1 activity show that photodynamic action generates oxidative stress in the treated cells. P-gp appears to play a role in the intracellular accumulation of Ph II. Therefore the efficacy of PDT on multidrug-resistant cells depends on the affinity of P-gp to the photosensitizer used. The weaker accumulation of photosensitizing agents enhances the antioxidant response, and this could influence the efficacy of PDT.

Anna Marcinkowska

2007-06-01

335

Antimicrobial susceptibility of multidrug-resistant (MDR) and extensively drug-resistant (XDR) Enterobacteriaceae isolates to fosfomycin  

OpenAIRE

Abstract The advancing antimicrobial drug resistance among Enterobacteriaceae renders the evaluation of potential novel therapeutic options necessary. We sought to evaluate the in vitro antimicrobial activity of fosfomycin against multidrug-resistant (MDR) Enterobacteriaceae isolates. Antimicrobial susceptibility to fosfomycin and 12 additional antibiotics of MDR Enterobacteriaceae isolates collected between November 2007 and April 2009 at the University Hospital of Heraklion, Cret...

Falagas, Matthew E.; Maraki, Sofia; Karageorgopoulos, Drosos E.; Kastoris, Antonia C.; Mavromanolakis, Emmanuel; Samonis, George

2010-01-01

336

The Phosphodiesterase-5 Inhibitor Vardenafil Is a Potent Inhibitor of ABCB1/P-Glycoprotein Transporter  

Science.gov (United States)

One of the major causes of chemotherapy failure in cancer treatment is multidrug resistance (MDR) which is mediated by the ABCB1/P-glycoprotein. Previously, through the use of an extensive screening process, we found that vardenafil, a phosphodiesterase 5 (PDE-5) inhibitor significantly reverses MDR in ABCB1 overexpressing cancer cells, and its efficacy was greater than that of tadalafil, another PDE-5 inhibitor. The present study was designed to determine the reversal mechanisms of vardenafil and tadalafil on ABC transporters-mediated MDR. Vardenafil or tadalafil alone, at concentrations up to 20 µM, had no significant toxic effects on any of the cell lines used in this study, regardless of their membrane transporter status. However, vardenafil when used in combination with anticancer substrates of ABCB1, significantly potentiated their cytotoxicity in ABCB1 overexpressing cells in a concentration-dependent manner, and this effect was greater than that of tadalafil. The sensitivity of the parenteral cell lines to cytotoxic anticancer drugs was not significantly altered by vardenafil. The differential effects of vardenafil and tadalafil appear to be specific for the ABCB1 transporter as both vardenafil and tadalafil had no significant effect on the reversal of drug resistance conferred by ABCC1 (MRP1) and ABCG2 (BCRP) transporters. Vardenafil significantly increased the intracellular accumulation of [3H]-paclitaxel in the ABCB1 overexpressing KB-C2 cells. In addition, vardenafil significantly stimulated the ATPase activity of ABCB1 and inhibited the photolabeling of ABCB1 with [125I]-IAAP. Furthermore, Western blot analysis indicated the incubation of cells with either vardenafil or tadalafil for 72 h did not alter ABCB1 protein expression. Overall, our results suggest that vardenafil reverses ABCB1-mediated MDR by directly blocking the drug efflux function of ABCB1. PMID:21552528

Ding, Pei-Rong; Tiwari, Amit K.; Ohnuma, Shinobu; Lee, Jeferson W. K. K.; An, Xin; Dai, Chun-Ling; Lu, Qi-Si; Singh, Satyakam; Yang, Dong-Hua; Talele, Tanaji T.; Ambudkar, Suresh V.; Chen, Zhe-Sheng

2011-01-01

337

The molecular interaction of a copper chelate with human P-glycoprotein.  

Science.gov (United States)

One of the major reasons for multidrug resistance (MDR) in cancer is the overexpression of P-glycoprotein (P-gp, ABCB1), a drug efflux pump. A novel copper complex, namely, copper (II) N-(2-hydroxyacetophenone) glycinate (CuNG) previously synthesized and characterized by the authors had been tested in this study. In a cell-based assay system with human MDR1 cDNA overexpressed mouse fibroblast NIH MDR1-G185 cell line, we demonstrated that this metal complex can directly interact with this transporter. As CuNG increased cellular accumulation of doxorubicin in P-gp-expressing cells, we presumed that of CuNG may be potential to reverse P-gp-mediated drug resistance probably by lowering the P-gp expression at the protein as well as mRNA level. Interestingly, our studies on UIC2 (a conformation sensitive monoclonal antibody) binding assay indicated the direct interaction of CuNG with P-gp. However, CuNG did not compete for the substrate binding as photoaffinity labeling of P-gp with a substrate analog [(125)I] iodoarylazidoprazosin ([(125)I] IAAP) showed approximately twofold increase in [(125)I] IAAP binding in presence of CuNG. In vitro study showed that CuNG significantly stimulated P-gp-specific ATPase activity in isolated membrane preparations from NIH MDR1-G185 cells. This result further confirmed the CuNG-P-gp direct interaction. This study also demonstrated that CuNG has a drug interaction site different from verapamil-, vinblastine- and progesterone-binding sites on P-gp. Taken together, this is the first report of molecular interaction of any Schiff's base metal chelate CuNG with human P-gp. This information may be useful to design more efficacious nontoxic metal-based drugs as MDR-reversing agents. PMID:22258826

Ghosh, Ruma Dey; Chakraborty, Paramita; Banerjee, Kaushik; Adhikary, Arghya; Sarkar, Avijit; Chatterjee, Mitali; Das, Tanya; Choudhuri, Soumitra Kumar

2012-05-01

338

The phosphodiesterase-5 inhibitor vardenafil is a potent inhibitor of ABCB1/P-glycoprotein transporter.  

Science.gov (United States)

One of the major causes of chemotherapy failure in cancer treatment is multidrug resistance (MDR) which is mediated by the ABCB1/P-glycoprotein. Previously, through the use of an extensive screening process, we found that vardenafil, a phosphodiesterase 5 (PDE-5) inhibitor significantly reverses MDR in ABCB1 overexpressing cancer cells, and its efficacy was greater than that of tadalafil, another PDE-5 inhibitor. The present study was designed to determine the reversal mechanisms of vardenafil and tadalafil on ABC transporters-mediated MDR. Vardenafil or tadalafil alone, at concentrations up to 20 µM, had no significant toxic effects on any of the cell lines used in this study, regardless of their membrane transporter status. However, vardenafil when used in combination with anticancer substrates of ABCB1, significantly potentiated their cytotoxicity in ABCB1 overexpressing cells in a concentration-dependent manner, and this effect was greater than that of tadalafil. The sensitivity of the parenteral cell lines to cytotoxic anticancer drugs was not significantly altered by vardenafil. The differential effects of vardenafil and tadalafil appear to be specific for the ABCB1 transporter as both vardenafil and tadalafil had no significant effect on the reversal of drug resistance conferred by ABCC1 (MRP1) and ABCG2 (BCRP) transporters. Vardenafil significantly increased the intracellular accumulation of [(3)H]-paclitaxel in the ABCB1 overexpressing KB-C2 cells. In addition, vardenafil significantly stimulated the ATPase activity of ABCB1 and inhibited the photolabeling of ABCB1 with [(125)I]-IAAP. Furthermore, Western blot analysis indicated the incubation of cells with either vardenafil or tadalafil for 72 h did not alter ABCB1 protein expression. Overall, our results suggest that vardenafil reverses ABCB1-mediated MDR by directly blocking the drug efflux function of ABCB1. PMID:21552528

Ding, Pei-Rong; Tiwari, Amit K; Ohnuma, Shinobu; Lee, Jeferson W K K; An, Xin; Dai, Chun-Ling; Lu, Qi-Si; Singh, Satyakam; Yang, Dong-Hua; Talele, Tanaji T; Ambudkar, Suresh V; Chen, Zhe-Sheng

2011-01-01

339

Expression of the human multidrug transporter in insect cells by a recombinant baculovirus  

Energy Technology Data Exchange (ETDEWEB)

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.

Germann, U.A.; Willingham, M.C.; Pastan, I.; Gottesman, M.M. (National Institutes of Health, Bethesda, MD (USA))

1990-03-06

340

DNA Sequence Analysis of Plasmids from Multidrug Resistant Salmonella enterica Serotype Heidelberg Isolates  

OpenAIRE

Salmonella enterica serovar Heidelberg is among the most detected serovars in swine and poultry, ranks among the top five serotypes associated with human salmonellosis and is disproportionately associated with invasive infections and mortality in humans. Salmonella are known to carry plasmids associated with antimicrobial resistance and virulence. To identify plasmid-associated genes in multidrug resistant S. enterica serovar Heidelberg, antimicrobial resistance plasmids from five isolates we...

Han, Jing; Lynne, Aaron M.; David, Donna E.; Tang, Hailin; Xu, Joshua; Nayak, Rajesh; Kaldhone, Pravin; Logue, Catherine M.; Foley, Steven L.

2012-01-01

341

Molecular Characterization of Multidrug-Resistant Escherichia coli Isolates from Irish Cattle Farms?†  

OpenAIRE

This study describes the genotypic characteristics of a collection of 100 multidrug-resistant (MDR) Escherichia coli strains recovered from cattle and the farm environment in Ireland in 2007. The most prevalent antimicrobial resistance identified was to streptomycin (100%), followed by tetracycline (99%), sulfonamides (98%), ampicillin (82%), and neomycin (62%). Resistance was mediated predominantly by strA-strB (92%), tetA (67%), sul2 (90%), blaTEM (79%), and aphA1 (63%) gene markers, respec...

Karczmarczyk, Maria; Walsh, Ciara; Slowey, Rosemarie; Leonard, Nola; Fanning, Se?amus

2011-01-01

342

A composite polymer nanoparticle overcomes multidrug resistance and ameliorates doxorubicin-associated cardiomyopathy  

OpenAIRE

Acquired chemotherapy resistance is a major contributor to treatment failure in oncology. For example, the efficacy of the common anticancer agent doxorubicin (DOX) is limited by the emergence of multidrug resistance (MDR) phenotype in cancer cells. While dose escalation of DOX can circumvent such resistance to a degree, this is precluded by the appearance of cardiotoxicity, a particularly debilitating condition in children. In vitro studies have established the ability of the natural phytoch...

Pramanik, Dipankar; Campbell, Nathaniel R.; Das, Samarjit; Gupta, Sonal; Chenna, Venugopal; Bisht, Savita; Sysa-shah, Polina; Bedja, Djahida; Karikari, Collins; Steenbergen, Charles; Gabrielson, Kathleen L.; Maitra, Amarnath; Maitra, Anirban

2012-01-01

343

Priorities in the prevention and control of multidrug-resistant Enterobacteriaceae in hospitals.  

LENUS (Irish Health Repository)

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.

Khan, A S

2012-10-01

344

The crystal structure of multidrug-resistance regulator RamR with multiple drugs.  

Science.gov (United States)

RamR is a transcriptional repressor of the gene-encoding RamA protein, which controls the expression of the multidrug efflux system genes acrAB-tolC. RamR is an important multidrug-resistance factor, however, its structure and the identity of the molecules to which it responds have been unknown. Here, we report the crystal structure of RamR in complex with multiple drugs, including berberine, crystal violet, dequalinium, ethidium bromide and rhodamine 6G. All compounds are found to interact with Phe155 of RamR, and each compound is surrounded by different amino acid residues. Binding of these compounds to RamR reduces its DNA-binding affinity, which results in the increased expression of ramA. Our results reveal significant flexibility in the substrate-recognition region of RamR, which regulates the bacterial efflux participating in multidrug resistance. PMID:23800819

Yamasaki, Suguru; Nikaido, Eiji; Nakashima, Ryosuke; Sakurai, Keisuke; Fujiwara, Daisuke; Fujii, Ikuo; Nishino, Kunihiko

2013-01-01

345

Combination of amikacin and doxycycline against multidrug-resistant and extensively drug-resistant tuberculosis.  

Science.gov (United States)

The objective of this study was to assess the activity of amikacin in combination with doxycycline against clinical strains of Mycobacterium tuberculosis in the search for new strategies against multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis. The study included 28 clinical M. tuberculosis strains, comprising 5 fully susceptible, 1 isoniazid-resistant, 17 MDR, 1 poly-resistant (streptomycin/isoniazid), 1 rifampicin-resistant and 3 XDR isolates, as well as the laboratory strain M. tuberculosis H37Rv. Minimum inhibitory concentrations (MICs) were determined using a modified chequerboard methodology in a BACTEC™ MGIT™ 960 System. Fractional inhibitory concentration indices (FICIs) were calculated, and synergy, indifference or antagonism was assessed. Whole-genome sequencing was performed to investigate the genetic basis of synergy, indifference or antagonism. The MIC50 and MIC90 values (MICs that inhibit 50% and 90% of the isolates, respectively) were, respectively, 0.5mg/L and 1.0mg/L for amikacin and 8mg/L and 16mg/L for doxycycline. The combination of amikacin and doxycycline showed a synergistic effect in 18 of the 29 strains tested and indifference in 11 strains. Antagonism was not observed. A streptomycin resistance mutation (K43R) was associated with indifference. In conclusion, the benefit of addition of doxycycline to an amikacin-containing regimen should be explored since in vitro results in this study indicate either synergy or indifference. Moreover, doxycycline also has immunomodulatory effects. PMID:25717028

Gonzalo, Ximena; Casali, Nicola; Broda, Agnieszka; Pardieu, Claire; Drobniewski, Francis

2015-04-01

346

Prevalence of multidrug resistant pathogens in children with urinary tract infection: a retrospective analysis  

Directory of Open Access Journals (Sweden)

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.

Srinivasan S, Madhusudhan NS

2014-11-01

347

Worldwide Occurrence of Integrative Conjugative Element Encoding Multidrug Resistance Determinants in Epidemic Vibrio cholerae O1  

Science.gov (United States)

In the last decades, there has been an increase of cholera epidemics caused by multidrug resistant strains. Particularly, the integrative and conjugative element (ICE) seems to play a major role in the emergence of multidrug resistant Vibrio cholerae. This study fully characterized, by whole genome sequencing, new ICEs carried by multidrug resistant V. cholerae O1 strains from Nigeria (2010) (ICEVchNig1) and Nepal (1994) (ICEVchNep1). The gene content and gene order of these two ICEs are the same, and identical to ICEVchInd5, ICEVchBan5 and ICEVchHai1 previously identified in multidrug resistant V. cholerae O1. This ICE is characterized by dfrA1, sul2, strAB and floR antimicrobial resistance genes, and by unique gene content in HS4 and HS5 ICE regions. Screening for ICEs, in publicly available V. cholerae genomes, revealed the occurrence and widespread distribution of this ICE among V. cholerae O1. Metagenomic analysis found segments of this ICE in marine environments far from the direct influence of the cholera epidemic. Therefore, this study revealed the epidemiology of a spatio-temporal prevalent ICE in V. cholerae O1. Its occurrence and dispersion in V. cholerae O1 strains from different continents throughout more than two decades can be indicative of its role in the fitness of the current pandemic lineage. PMID:25265418

Marin, Michel A.; Fonseca, Erica L.; Andrade, Bruno N.; Cabral, Adriana C.; Vicente, Ana Carolina P.

2014-01-01

348

Enhanced potency of daunorubicin against multidrug resistant subline KB-ChR-8-5-11 by a pulsed magnetic field.  

Science.gov (United States)

Tumor cell resistance to many unrelated anticancer drugs is a major obstacle during cancer chemotherapy. One mechanism of drug resistance is thought to be due to the efflux of anticancer drugs caused by P-glycoprotein. In recent years, magnetic fields have been found to enhance the potency of anticancer drugs, with favorable modulation of cancer therapy. In this study, KB-ChR-8-5-11, a multidrug resistant (MDR) human carcinoma subline, was used as a model to evaluate the ability of pulsed magnetic fields (PMF) to modulate the potency of daunorubicin (DNR) in vivo and to determine the appropriate order of exposure to drugs and PMF using an in vitro cytotoxicity assay. Solenoid coils with a ramped pulse current source were used at 250 pulses per second for both in vivo and in vitro experiments. For the in vivo study, KB-ChR-8-5-11 cells were inoculated into thymic Balbc-nu/nu female mice. Treatment was begun when the average tumor volume reached 250-450 mm3. Treatment consisted of whole body exposure to PMF for one hour, followed immediately by intravenous (i.v.) injection of 8 mg/kg DNR designated as day 0, and repeated on days 7 and 14. Among the various groups, significant differences in the tumor volume were found between PMF + saline and PMF + DNR groups (p = 0.0107) at 39 days and 42 days (p = 0.0101). No mice died in the PMF alone group, and no toxicity attributable to PMF was found during the experimental period. For the in vitro studies, the sulforhodamine blue (SRB) cytotoxicity assay was used to determine the effect of the sequence which cells are exposed to PMF and/or DNR. Cells were exposed to PMF either before (pre-PMF) or after (post-PMF) drug was added. Results showed that the IC50 was significantly different between controls and pre-PMF + DNR groups (P = 0.0096, P = 0.0088). The IC50 of the post-PMF + DNR group was not found to be significantly different from control groups. Thus, the data in this report demonstrates that PMF enhanced the potency of DNR against KB-ChR-8-5-11 xenograft in vivo, while the efficacy of DNR was potentiated in vitro by PMF exposure only when PMF exposure occurred in the presence of drug. The data in vitro suggest that the mechanism by which PMFs modulate DNR's potency may be by inhibition of the efflux pump, P-glycoprotein. Further work to determine conditions for maximum modulation of drug potency by PMFs is warranted. PMID:9216668

Liang, Y; Hannan, C J; Chang, B K; Schoenlein, P V

1997-01-01

349

Antimycobacterial Assessment of Salicylanilide Benzoates including Multidrug-Resistant Tuberculosis Strains  

Directory of Open Access Journals (Sweden)

Full Text Available The increasing emergence especially of drug-resistant tuberculosis has led to a strong demand for new anti-tuberculosis drugs. Eighteen salicylanilide benzoates were evaluated for their inhibition potential against Mycobacterium tuberculosis, Mycobacterium avium and two strains of Mycobacterium kansasii; minimum inhibitory concentration values ranged from 0.5 to 16 ?mol/L. The most active esters underwent additional biological assays. Four benzoates inhibited effectively the growth of five multidrug-resistant strains and one extensively drug-resistant strain of M. tuberculosis at low concentrations (0.25–2 ?mol/L regardless of the resistance patterns. The highest rate of multidrug-resistant mycobacteria inhibition expressed 4-chloro-2-[4-(trifluoromethyl-phenylcarbamoyl]phenyl benzoate (0.25–1 ?mol/L. Unfortunately, the most potent esters were still considerably cytotoxic, although mostly less than their parent salicylanilides.

Ji?ina Stola?íková

2012-10-01

350

Antimycobacterial assessment of Salicylanilide benzoates including multidrug-resistant tuberculosis strains.  

Science.gov (United States)

The increasing emergence especially of drug-resistant tuberculosis has led to a strong demand for new anti-tuberculosis drugs. Eighteen salicylanilide benzoates were evaluated for their inhibition potential against Mycobacterium tuberculosis, Mycobacterium avium and two strains of Mycobacterium kansasii; minimum inhibitory concentration values ranged from 0.5 to 16 ?mol/L. The most active esters underwent additional biological assays. Four benzoates inhibited effectively the growth of five multidrug-resistant strains and one extensively drug-resistant strain of M. tuberculosis at low concentrations (0.25–2 ?mol/L) regardless of the resistance patterns. The highest rate of multidrug-resistant mycobacteria inhibition expressed 4-chloro-2-[4-(trifluoromethyl)-phenylcarbamoyl]phenyl benzoate (0.25–1 ?mol/L). Unfortunately, the most potent esters were still considerably cytotoxic, although mostly less than their parent salicylanilides. PMID:23114617

Krátký, Martin; Vinšová, Jarmila; Stola?íková, Ji?ina

2012-01-01

351

Sorcin, a calcium binding protein involved in the multidrug resistance mechanisms in cancer cells.  

Science.gov (United States)

Sorcin is a penta-EF hand calcium binding protein, which participates in the regulation of calcium homeostasis in cells. Sorcin regulates calcium channels and exchangers located at the plasma membrane and at the endo/sarcoplasmic reticulum (ER/SR), and allows high levels of calcium in the ER to be maintained, preventing ER stress and possibly, the unfolded protein response. Sorcin is highly expressed in the heart and in the brain, and overexpressed in many cancer cells. Sorcin gene is in the same amplicon as other genes involved in the resistance to chemotherapeutics in cancer cells (multi-drug resistance, MDR) such as ABCB4 and ABCB1; its overexpression results in increased drug resistance to a number of chemotherapeutic agents, and inhibition of sorcin expression by sorcin-targeting RNA interference leads to reversal of drug resistance. Sorcin is increasingly considered a useful marker of MDR and may represent a therapeutic target for reversing tumor multidrug resistance. PMID:25197934

Colotti, Gianni; Poser, Elena; Fiorillo, Annarita; Genovese, Ilaria; Chiarini, Valerio; Ilari, Andrea

2014-01-01

352

Sorcin, a Calcium Binding Protein Involved in the Multidrug Resistance Mechanisms in Cancer Cells  

Directory of Open Access Journals (Sweden)

Full Text Available Sorcin is a penta-EF hand calcium binding protein, which participates in the regulation of calcium homeostasis in cells. Sorcin regulates calcium channels and exchangers located at the plasma membrane and at the endo/sarcoplasmic reticulum (ER/SR, and allows high levels of calcium in the ER to be maintained, preventing ER stress and possibly, the unfolded protein response. Sorcin is highly expressed in the heart and in the brain, and overexpressed in many cancer cells. Sorcin gene is in the same amplicon as other genes involved in the resistance to chemotherapeutics in cancer cells (multi-drug resistance, MDR such as ABCB4 and ABCB1; its overexpression results in increased drug resistance to a number of chemotherapeutic agents, and inhibition of sorcin expression by sorcin-targeting RNA interference leads to reversal of drug resistance. Sorcin is increasingly considered a useful marker of MDR and may represent a therapeutic target for reversing tumor multidrug resistance.

Gianni Colotti

2014-09-01

353

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)

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 phase III xenobiotic transporter). P-glycoprotein is present in the intestinal mucosal lining and restricts absorption of certain carcinogens, among these polycyclic aromatic hydrocarbons. Moreover, P-glycoprotein transports various endogenous substrates such as cytokines and chemokines involved in inflammation, and may thereby affect the risk of malignity. Hence, genetic variations that modify the function of P-glycoprotein may be associated with the risk of colorectal cancer (CRC). We have previously found an association between the MDR1 intron 3 G-rs3789243-A polymorphism and the risk of CRC in a Danish study population. The aim of this study was to investigate if this MDR1 polymorphism was associated with risk ofcolorectal adenoma (CA) and CRC in the Norwegian population. Methods: Using a case-control design, the association between the MDR1 intron 3 G-rs3789243-A polymorphism and the risk of colorectal carcinomas and adenomas in the Norwegian population was assessed in 167 carcinomas, 990 adenomas, and 400 controls. Genotypes were determined by allelic discrimination. Odds ratio (OR) and 95 confidence interval (95% CI) were estimated by binary logistic regression. Results: No association was found between the MDR1 polymorphism (G-rs3789243-A) and colorectal adenomas or cancer. Carriers of the variant allele of MDR1 intron 3 had odds ratios (95% CI) of 0.97 (0.72-1.29) for developing adenomas, and 0.70 (0.41-1.21) for colorectal cancer, respectively, compared to homozygous wild type carriers. Conclusion: The MDR1 intron 3 (G-rs3789243-A) polymorphism was not associated with a risk of colorectal adenomas or carcinomas in the present Norwegian study group. Thus, this MDR1 polymorphism does not seem to play an important role in colorectal carcinogenesis in this population.

Andersen, V.; Agerstjerne, L.

2009-01-01

354

Treatment of complicated intra-abdominal infections in the era of multi-drug resistant Bacteria  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract The management of severe intra-abdominal infections remains a major challenge facing surgeons and intensive care physicians, because of its association with high morbidity and mortality. Surgical management and intensive care medicine have constantly improved, but in the recent years a rapidly continuing emergence of resistant pathogens led to treatment failure secondary to infections with multi-drug resistant bacteria. In secondary peritonitis the rate of resistant germs at the initial operation is already 30%. The lack of effective antibiotics against these pathogens resulted in the development of new broad-spectrum compounds and antibiotics directed against resistant germs. But so far no "super-drug" with efficacy against all resistant bacteria exists. Even more, soon after their approval, reports on resistance against these novel drugs have been reported, or the drugs were withdrawn from the market due to severe side effects. Since pharmaceutical companies reduced their investigations on antibiotic research, only few new antimicrobial derivates are available. In abdominal surgery you may be in fear that in the future more and more patients with tertiary peritonitis secondary to multi-drug resistant species are seen with an increase of mortality after secondary peritonitis. This article reviews the current treatment modalities for complicated intra-abdominal infections with special reference to the antibiotic treatment of complicated intra-abdominal infections with multi-drug resistant species.

Herzog T

2010-11-01

355

Molecular characterization of multidrug-resistant Shigella spp. of food origin.  

Science.gov (United States)

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. PMID:25485847

Ahmed, Ashraf M; Shimamoto, Tadashi

2015-02-01

356

Genome Resequencing of the Virulent and Multidrug-Resistant Reference Strain Clostridium difficile 630.  

Science.gov (United States)

We resequenced the complete genome of the virulent and multidrug-resistant pathogen Clostridium difficile strain 630. A combination of single-molecule real-time and Illumina sequencing technology revealed the presence of an additional rRNA gene cluster, additional tRNAs, and the absence of a transposon in comparison to the published and reannotated genome sequence. PMID:25858846

Riedel, Thomas; Bunk, Boyke; Thürmer, Andrea; Spröer, Cathrin; Brzuszkiewicz, Elzbieta; Abt, Birte; Gronow, Sabine; Liesegang, Heiko; Daniel, Rolf; Overmann, Jörg

2015-01-01

357

4-Isoxazolyl-1,4-dihydropyridines exhibit binding at the multidrug resistance transporter  

Science.gov (United States)

The 4-Isoxazolyl-dihydropyridines (IDHPs) exhibit inhibition of the multidrug-resistance transporter (MDR-1), and exhibit an SAR distinct from their activity at voltage gated calcium channels (VGCC). Among the four most active IDHPs, three were branched at C-5 of the isoxazole, including the most active analog, 1k. PMID:23063517

Hulubei, Victoria; Meikrantz, Scott B.; Quincy, David A.; Houle, Tina; McKenna, John I; Rogers, Mark E.; Steiger, Scott; Natale, N.R.

2012-01-01

358

PolyHPMA conjugates with inhibitors of ABC transporter overcoming multidrug resistance in cancer treatment.  

Czech Academy of Sciences Publication Activity Database

Tsukuba : Tsukuba Bioengineering Initiative, 2013. s. 53. [International Conference on Biomaterials Science in Tsukuba /2./ - ICBS 2013. 19.03.2013-22.03.2013, Tsukuba] R&D Projects: GA ?R GAP301/12/1254 Institutional support: RVO:61389013 ; RVO:61388971 Keywords : multidrug resistance * drug delivery systems * ABC transporter inhibitors Subject RIV: CD - Macromolecular Chemistry; FD - Oncology ; Hematology (MBU-M)

Šubr, Vladimír; Kabešová, Martina; Sivák, Ladislav; Ulbrich, Karel; Ková?, Marek; ?íhová, Blanka

359

Isolation and characterization of antimicrobial compounds in plant extracts against multidrug-resistant Acinetobacter baumannii.  

Science.gov (United States)

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. PMID:23630600

Miyasaki, Yoko; Rabenstein, John D; Rhea, Joshua; Crouch, Marie-Laure; Mocek, Ulla M; Kittell, Patricia Emmett; Morgan, Margie A; Nichols, Wesley Stephen; Van Benschoten, M M; Hardy, William David; Liu, George Y

2013-01-01

360

Nitrate reductase assay using sodium nitrate for rapid detection of multidrug resistant tuberculosis  

OpenAIRE

We validated the nitrate reductase assay (NRA) for the detection of multidrug-resistant Mycobacterium tuberculosis (MDR-TB) using sodium nitrate (NaNO3) in replacement of potassium nitrate (KNO3) as nitrate source. NaNO3 is cheaper than KNO3 and has no restriction on use which facilitates the implementation of NRA to detect MDR-TB.

Maíra Bidart Macedo; Andrea Von Groll; Krista Fissette; Juan Carlos Palomino; Pedro Eduardo Almeida da Silva; Anandi Martin

2012-01-01

361

Pacemaker Lead Endocarditis Due to Multidrug-Resistant Corynebacterium striatum Detected with Sonication of the Device ?  

OpenAIRE

Corynebacterium striatum is a commensal of human skin and has been recently recognized as an emerging pathogen. A case of nosocomial pacemaker lead endocarditis due to a multidrug-resistant C. striatum strain is described, highlighting the role of sonication as a diagnostic tool in cardiac device infections.

Oliva, Alessandra; Belvisi, Valeria; Iannetta, Marco; Andreoni, Carolina; Mascellino, Maria T.; Lichtner, Miriam; Vullo, Vincenzo; Mastroianni, Claudio M.

2010-01-01

362

Downregulation of taurine uptake in multidrug resistant Ehrlich ascites tumor cells  

DEFF Research Database (Denmark)

In daunorubicin resistant Ehrlich ascites tumor cells (DNR), the initial taurine uptake was reduced by 56% as compared to the parental, drug sensitive Ehrlich cells. Kinetic experiments indicated that taurine uptake in Ehrlich cells occurs via both high- and low-affinity transporters. The maximal rate constant for the initial taurine uptake was reduced by 45% (high-affinity system) and 49% (low affinity system) in the resistant subline whereas the affinity of the transporters to taurine was unchanged. By immunoblotting we identified 3 TauT protein bands in the 50-70 kDa region. A visible reduction in the intensity of the band with the lowest molecular weight was observed in resistant cells. Quantitative RT-PCR indicated a significant reduction in the amount of taurine transporter mRNA in the resistant cells. Drug resistance in DNR Ehrlich cells is associated with overexpression of the mdr1 gene product P-glycoprotein (P-gp). Using 5 progressively DNR resistant Ehrlich cell sublines with different P-gp expression pattern no correlation between taurine uptake and P-gp expression was found. Taurine uptake in MDR1 transfected NIH/3T3 mouse fibroblasts was in contrast to the findings in Ehrlich cells increased compared to the parental fibroblasts. It is concluded that the reduced taurine uptake in resistant Ehrlich cells reflects a down regulation of the taurine transporter at the mRNA and protein level and it is most probably not related to P-gp overexpression.

Poulsen, K A; Litman, Thomas

2002-01-01

363

P-Glycoprotein Limits Oral Availability, Brain Penetration, and Toxicity of an Anionic Drug, the Antibiotic Salinomycin?  

OpenAIRE

Salinomycin is a polyether organic anion that is extensively used as a coccidiostatic antibiotic in poultry and commonly fed to ruminant animals to improve feed efficiency. However, salinomycin also causes severe toxicity when accidentally fed to animals in high doses. In addition, humans are highly sensitive to salinomycin and severe toxicity has been reported. Multidrug efflux transporters like P-glycoprotein (P-gp), BCRP, and MRP2 are highly expressed in the intestine and can restrict the ...

Lagas, Jurjen S.; Sparidans, Rolf W.; Waterschoot, Robert A. B.; Wagenaar, Els; Beijnen, Jos H.; Schinkel, Alfred H.

2007-01-01

364

Characterization of integrons and resistance genes in multidrug-resistant Salmonella enterica isolated from meat and dairy products in Egypt.  

Science.gov (United States)

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. ?-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 meat and dairy products in Egypt, with the possibility of their transfer to humans leading to therapeutic failure. Therefore, the overuse of antibiotics in animals should be drastically reduced in developing countries. PMID:25113044

Ahmed, Ashraf M; Shimamoto, Toshi; Shimamoto, Tadashi

2014-10-17

365

Multidrug resistant bacteria in companion animals: impact on animal health and zoonotic aspects  

DEFF Research Database (Denmark)

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 health, treatment options and potential zoonotic impact.

Damborg, Peter Panduro

366

Blonanserin, a novel atypical antipsychotic agent not actively transported as substrate by P-glycoprotein.  

Science.gov (United States)

Although blonanserin, a novel atypical antipsychotic agent with dopamine D(2)/serotonin 5-HT(2A) antagonistic properties, displays good brain distribution, the mechanism of this distribution has not been clarified. P-glycoprotein [(P-gp) or multidrug resistance protein 1 (MDR1)] is an efflux transporter expressed in the brain and plays an important role in limiting drug entry into the central nervous system (CNS). In particular, P-gp can affect the pharmacokinetics and efficacy of antipsychotics, and exacerbate or soothe their adverse effects. In this study, we conducted in vitro and in vivo experiments to determine whether blonanserin is a P-gp substrate. Risperidone and its active metabolite 9-hydroxyrisperidone, both of which are P-gp substrates, were used as reference drugs. Affinity of blonanserin, risperidone, and 9-hydroxyrisperidone for P-gp was evaluated by in vitro transcellular transport across LLC-PK1, human MDR1 cDNA-transfected LLC-PK1 (LLC-MDR1), and mouse Mdr1a cDNA-transfected LLC-PK1 (LLC-Mdr1a). In addition, pharmacokinetic parameters in the brain and plasma (B/P ratio) of test compounds were measured in mdr1a/1b knockout (KO) and wild-type (WT) mice. The results of in vitro experiments revealed that P-gp does not actively transport blonanserin as a substrate in humans or mice. In addition, blonanserin displayed comparable B/P ratios in KO and WT mice, whereas B/P ratios of risperidone and 9-hydroxyrisperidone differed markedly in these animals. Our results indicate that blonanserin is not a P-gp substrate and therefore its brain distribution is unlikely to be affected by this transporter. PMID:22691713

Inoue, Tomoko; Osada, Kenichi; Tagawa, Masaaki; Ogawa, Yuriko; Haga, Toshiaki; Sogame, Yoshihisa; Hashizume, Takanori; Watanabe, Takashi; Taguchi, Atsushi; Katsumata, Takashi; Yabuki, Masashi; Yamaguchi, Noboru

2012-10-01

367

Evidence for two nonidentical drug-interaction sites in the human P-glycoprotein.  

Science.gov (United States)

Human P-glycoprotein (Pgp) confers multidrug resistance to cancer cells by ATP-dependent extrusion of a great many structurally dissimilar hydrophobic compounds. The manner in which Pgp recognizes these different substrates is unknown. The protein shows internal homology between its N- and C-terminal halves, each comprised of six putative transmembrane helices and a consensus ATP binding/utilization site. Photoactive derivatives of certain Pgp substrates specifically label two regions, one on each half of the protein. In this study, using [125I]iodoarylazidoprazosin ([125I]IAAP), a photoactive analog of prazosin, we have demonstrated the presence of two nonidentical drug-interaction sites within Pgp. Taking advantage of a highly susceptible trypsin cleavage site in the linker region of Pgp, we characterized the [125I]IAAP binding to the N- and C-terminal halves. cis(Z)-Flupentixol, a modulator of Pgp function, preferentially increased the affinity of [125I]IAAP for the C-terminal half of the protein (C-site) by reducing the Kd from 20 to 6 nM without changing the labeling or affinity (Kd = 42-46 nM) of the N-terminal half (N-site). Also, the concentration of vinblastine (Pgp substrate) and cyclosporin A (Pgp modulator) required for 50% inhibition of [125I]IAAP binding to the C-site was increased 5- to 6-fold by cis(Z)-flupentixol without any effect on the N-site. In addition, [125I]IAAP binding to the N-site was less susceptible than to C-site to inhibition by vanadate which blocks ATP hydrolysis and drug transport. These data demonstrate the presence of at least two nonidentical substrate interaction sites in Pgp. PMID:9380680

Dey, S; Ramachandra, M; Pastan, I; Gottesman, M M; Ambudkar, S V

1997-09-30

368

Evidence for two nonidentical drug-interaction sites in the human?P-glycoprotein  

Science.gov (United States)

Human P-glycoprotein (Pgp) confers multidrug resistance to cancer cells by ATP-dependent extrusion of a great many structurally dissimilar hydrophobic compounds. The manner in which Pgp recognizes these different substrates is unknown. The protein shows internal homology between its N- and C-terminal halves, each comprised of six putative transmembrane helices and a consensus ATP binding/utilization site. Photoactive derivatives of certain Pgp substrates specifically label two regions, one on each half of the protein. In this study, using [125I]iodoarylazidoprazosin ([125I]IAAP), a photoactive analog of prazosin, we have demonstrated the presence of two nonidentical drug-interaction sites within Pgp. Taking advantage of a highly susceptible trypsin cleavage site in the linker region of Pgp, we characterized the [125I]IAAP binding to the N- and C-terminal halves. cis(Z)-Flupentixol, a modulator of Pgp function, preferentially increased the affinity of [125I]IAAP for the C-terminal half of the protein (C-site) by reducing the Kd from 20 to 6 nM without changing the labeling or affinity (Kd = 42–46 nM) of the N-terminal half (N-site). Also, the concentration of vinblastine (Pgp substrate) and cyclosporin A (Pgp modulator) required for 50% inhibition of [125I]IAAP binding to the C-site was increased 5- to 6-fold by cis(Z)-flupentixol without any effect on the N-site. In addition, [125I]IAAP binding to the N-site was less susceptible than to C-site to inhibition by vanadate which blocks ATP hydrolysis and drug transport. These data demonstrate the presence of at least two nonidentical substrate interaction sites in Pgp. PMID:9380680

Dey, Saibal; Ramachandra, Muralidhara; Pastan, Ira; Gottesman, Michael M.; Ambudkar, Suresh V.

1997-01-01

369

P-glycoprotein efflux pump expression and activity in Calu-3 cells.  

Science.gov (United States)

The purpose of this work was to determine if the sub-bronchial epithelial cell model, Calu-3, expresses the functionally active P-glycoprotein (Pgp) efflux pump. Calu-3 cells express lower levels of Pgp than both Caco-2 and A549 cells as determined by Western Blot analysis. In Calu-3 cells, accumulation of the Pgp substrates rhodamine 123 (Rh123) and calcein acetoxymethyl ester (calcein-AM) was increased in the presence of the specific Pgp inhibitors cyclosporin A (CsA), vinblastine, and taxol. Significant inhibition of Pgp activity was not observed until after 2 h in both cell lines. The organic anion/multidrug resistance associated protein-1 (MRP1) inhibitors, probenecid and indomethacin, did not affect Rh123 accumulation, whereas an increase in calcein accumulation was observed by both agents. The metabolic inhibitor sodium azide decreased the efflux of Rh123 out of Calu-3 cells to the same degree as CsA, supporting inhibition of an active, efflux pathway. The basolateral-to-apical transport of Rh123 was significantly higher than that in the reverse direction, indicating a secretory pathway of efflux that was inhibited 25-fold by CsA. Basolateral-to-apical transport of Rh123 was inhibited slightly with both MRP1 inhibitors; however, no significant effect of Rh123 net secretion was observed. Mixed inhibitor studies demonstrated that Rh123 efflux was mainly Pgp mediated. These results support an energy-dependent Pgp efflux pump pathway that is sensitive to inhibition with CsA in Calu-3 cells. PMID:11288109

Hamilton, K O; Backstrom, G; Yazdanian, M A; Audus, K L

2001-05-01

370

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

DEFF Research Database (Denmark)

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 obtained by docking into a homology model of P-gp, to supervised machine learning methods, such as Kappa nearest neighbor, support vector machine (SVM), random forest and binary QSAR, by using a large, structurally diverse data set. In addition, the applicability domain of the models was assessed using 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 ChemScore resulted in the correct prediction of 61 % of the external test set. This demonstrates that ligand-based models currently remain the methods of choice for accurately predicting P-gp inhibitors. However, structure-based classification offers information about possible drug/protein interactions, which helps in understanding the molecular basis of ligand-transporter interaction and could therefore also support lead optimization.

Klepsch, Freya; Poongavanam, Vasanthanathan

2014-01-01

371

Plasmid profiling of multidrug resistant Escherichia coli strains isolated from urinary tract infection patients  

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Full Text Available Introduction- Urinary tract infection is a common community-acquired bacterial disease. Escherichia coli is reported to be the major cause of urinary tract infection. Aim & Objective- The study was conducted with the aim of determining the antibiotic resistance pattern and plasmid profile of multidrug resistant Escherichia coli isolated from Urinary Tract Infection patients. Materials and Method- Antibiotic susceptibility tests were performed against E. coli following the protocol for the Kirby-Bauer disc diffusion method. Plasmid DNA was isolated following the protocol of Kado and Liu. Results- Multidrug resistant isolates exhibited high resistance to drugs like Amoxicillin, Cefixime, Ciprofloxacin, Cotrimethoxazole, Norfloxacin and Ofloxacin. The plasmid profiling showed that all, except one, isolate contained at least one plasmid. A band of approximately 23 kb was seen in most of the isolates.

Sabin Khadgi

2013-03-01

372

In silico structure-based screening of versatile P-glycoprotein inhibitors using polynomial empirical scoring functions  

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Full Text Available Sergey Shityakov, Carola FörsterDepartment of Anesthesia and Critical Care, University of Würzburg, Würzburg, GermanyAbstract: 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 (r2=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.Keywords: ATP-binding cassette transporter, P-gp inhibitors, multidrug resistance, molecular docking, POLSCORE

Shityakov S

2014-03-01

373