WorldWideScience
1

Cellular localization of the multidrug-resistance gene product P-glycoprotein in normal human tissues.  

OpenAIRE

Monoclonal antibody MRK16 was used to determine the location of P-glycoprotein, the product of the multidrug-resistance gene (MDR1), in normal human tissues. The protein was found to be concentrated in a small number of specific sites. Most tissues examined revealed very little P-glycoprotein. However, certain cell types in liver, pancreas, kidney, colon, and jejunum showed specific localization of P-glycoprotein. In liver, P-glycoprotein was found exclusively on the biliary canalicular front...

Thiebaut, F.; Tsuruo, T.; Hamada, H.; Gottesman, M. M.; Pastan, I.; Willingham, M. C.

1987-01-01

2

Spontaneous Reversal of P-Glycoprotein Expression in Multidrug Resistant Cell Lines  

OpenAIRE

Increased expression of P-glycoprotein encoded by the mdr-1 gene is a well-characterised mechanism for resistance to cancer chemotherapeutic drugs in cell lines. However, the P-glycoprotein expression after removal of the selection pressure has not fully been elucidated. The stability of P-glycoprotein expression in the presence (+) and absence (-) of vincristine (30 or 150 nM) was studied in multidrug resistant K562 cell lines (VCR30+, VCR150+, VCR30- and VCR150-) for 11 months. The P-glycop...

Green, Henrik; Lotfi, Kourosh; Zackrisson, Anna Lena; Peterson, Curt

2003-01-01

3

Multidrug-resistance P-glycoprotein (MDR1) secretes platelet-activating factor  

OpenAIRE

The human multidrug-resistance (MDR1) P-glycoprotein (Pgp) is an ATP-binding-cassette transporter (ABCB1) that is ubiquitously expressed. Often its concentration is high in the plasma membrane of cancer cells, where it causes multidrug resistance by pumping lipophilic drugs out of the cell. In addition, MDR1 Pgp can transport analogues of membrane lipids with shortened acyl chains across the plasma membrane. We studied a role for MDR1 Pgp in transport to the cell surface ...

Raggers, R. J.; Vogels, Ilse; Meer, Gerrit

2001-01-01

4

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

OpenAIRE

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 progressiv...

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

2003-01-01

5

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

6

Pharmacokinetic modeling of multidrug resistance P-glycoprotein transport of gamma-emitting substrates  

Energy Technology Data Exchange (ETDEWEB)

P-glycoprotein, the human multidrug resistance (MDR1) gene product, is an integral membrane protein expressed on the plasma membrane of MDR tumor cells and is the best characterized of a family of efflux transporters that confer chemotherapeutic resistance. The use of gamma-emitting {sup 99m}Tc-agents to image P-glycoprotein function in human tumors in vivo has been proposed. Net tumor cell content of {sup 99m}Tc-Sestamibi, {sup 99m}Tc-Tetrofosmin and several {sup 99m}Tc-Q-complexes ({sup 99m}Tc-Q58 and {sup 99m}Tc-Q63) are function of passive potential-dependent influx and MDR1 P-glycoprotein-mediated active extrusion. To better understand the overall fidelity of these P-glycoprotein substrates to report MDR activity in vivo in relation to tissue perfusion, a compartmental model of tracer pharmacokinetics was developed. Modeling indicates that tissue perfusion will impact pharmacokinetics in vivo in a manner that will tend to diminish P-glycoprotein-mediated phenotypic differences between tissues when they are perfusion-limited. However, dynamic imaging to extract efflux rate constants is independent of perfusion and may represent the highest quality methodology for collecting the desired information regarding activity of the efflux transporter. Much work remains to translate these concepts and biological targeting properties into clinical practice.

Bae, K. T.; Piwnica-Worms, D. [St. Louis, Washington Univ. (United States). Mallinckrodt Institute of Radiology. Lab. of Molecular Radiopharmacology]|[St. Louis, Washington Univ. (United States). Dept. of Molecular Biology and Pharmacology

1997-06-01

7

Pharmacokinetic modeling of multidrug resistance P-glycoprotein transport of gamma-emitting substrates  

International Nuclear Information System (INIS)

P-glycoprotein, the human multidrug resistance (MDR1) gene product, is an integral membrane protein expressed on the plasma membrane of MDR tumor cells and is the best characterized of a family of efflux transporters that confer chemotherapeutic resistance. The use of gamma-emitting 99mTc-agents to image P-glycoprotein function in human tumors in vivo has been proposed. Net tumor cell content of 99mTc-Sestamibi, 99mTc-Tetrofosmin and several 99mTc-Q-complexes 99mTc-Q58 and 99mTc-Q63) are function of passive potential-dependent influx and MDR1 P-glycoprotein-mediated active extrusion. To better understand the overall fidelity of these P-glycoprotein substrates to report MDR activity in vivo in relation to tissue perfusion, a compartmental model of tracer pharmacokinetics was developed. Modeling indicates that tissue perfusion will impact pharmacokinetics in vivo in a manner that will tend to diminish P-glycoprotein-mediated phenotypic differences between tissues when they are perfusion-limited. However, dynamic imaging to extract efflux rate constants is independent of perfusion and may represent the highest quality methodology for collecting the desired information regarding activity of the efflux transporter. Much work remains to translate these concepts and biological targeting properties into clinical practice

8

ZD6474 reverses multidrug resistance by directly inhibiting the function of P-glycoprotein  

OpenAIRE

P-glycoprotein (P-gp) pumps multiple types of drugs out of the cell, using energy generated from ATP, and confers multidrug resistance (MDR) on cancer cells. ZD6474 is an orally active, selective inhibitor of the vascular endothelial growth factor receptor, epidermal growth factor receptor, and rearranged during transfection tyrosine kinases. This study was designed to examine whether ZD6474 reverses P-gp-mediated MDR in cancer cells. Here, we show that clinically achievable levels of ZD6474 ...

Mi, Y.; Lou, L.

2007-01-01

9

Characterization of multidrug resistance P-glycoprotein transport function with an organotechnetium cation  

Energy Technology Data Exchange (ETDEWEB)

Multidrug resistance (MDR) in mammalian cells and tumors is associated with overexpression of an {approximately}170 integral membrane efflux transporter, the MDR1 P-glycoprotein. Hexakis(2-methoxyisobutyl isonitrile) technetium(I) (Tc-SESTAMIBI), a {gamma}-emitting lipophilic cationic metallopharmaceutical, has recently been shown to be a P-glycoprotein transport substrate. Exploiting the negligible lipid membrane adsorption properties of this organometallic substrate, we studied the transport kinetics, pharmacology, drug binding, and modulation of P-glycoprotein in cell preparations derived from a variety of species and selection strategies, including SW-1573, V79, Alex, and CHO drug-sensitive cells and in 77A, LZ-8, and Alex/A.5 MDR cells. Rapid cell accumulation (T{sub 1/2} {approx} 6 min) of the agent to a steady state was observed which was inversely proportional to immunodetectable levels of P-glycoprotein. Many MDR cytotoxic agents inhibited P-glycoprotein-mediated Tc-SESTAMIBI efflux, thereby enhancing organometallic cation accumulation. 70 refs., 7 figs., 2 tabs.

Piwnica-Worms, D.; Vallabhaneni, V.R. [Washington Univ. Medical School, St. Louis, MO (United States); Kronauge, J.F. [Harvard Medical School, Boston, MA (United States)] [and others

1995-09-26

10

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

OpenAIRE

We have shown previously that reserpine is an effective "modulator" of P-glycoprotein-associated multidrug resistance (MDR). In addition to enhancing drug cytotoxicity in our multidrug-resistant human leukemia cell line, CEM/VLB100, reserpine strongly competes with a photoactivatible analog of vinblastine, N-(p-azido-3-[125I]iodosalicyl)-N'-(beta-aminoethyl)vindesine, for binding to P-glycoprotein. We also demonstrated previously that there are three substructural domains present in many comp...

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

1989-01-01

11

Expression of hamster P-glycoprotein and multidrug resistance in DNA-mediated transformants of mouse LTA cells.  

OpenAIRE

The overexpression of a plasma membrane glycoprotein, P-glycoprotein, is strongly correlated with the expression of multidrug resistance. This phenotype (frequently observed in cell lines selected for resistance to a single drug) is characterized by cross resistance to many drugs, some of which are used in cancer chemotherapy. In the present study we showed that DNA-mediated transformants of mouse LTA cells with DNA from multidrug-resistant hamster cells acquired the multidrug resistance phen...

Deuchars, K. L.; Du, R. P.; Naik, M.; Evernden-porelle, D.; Kartner, N.; Bliek, A. M.; Ling, V.

1987-01-01

12

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) immunohistochem...

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

2009-01-01

13

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.

Machado C.G.

2003-01-01

14

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

OpenAIRE

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 G...

Safa, A. R.; Stern, R. K.; Choi, K.; Agresti, M.; Tamai, I.; Mehta, N. D.; Roninson, I. B.

1990-01-01

15

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

16

Effect of methylxanthines derived from pentoxifylline on P-glycoprotein mediated multidrug resistance  

International Nuclear Information System (INIS)

In this paper study of multidrug resistance (MDR) antitumor agents - P-glycoprotein (PGP) is presented. The ability of pentoxifylline (PTX) to depress resistance mediated by overexpression of PGP in mouse leukemic cell line L 121 ONCR resistant to vincristine (VCR) was described earlier. PTX depressed the resistance of these cells in a dose and time dependent manner. This effect was accompanied by increased level of [3H]-vincristine accumulation by these cells. The methylxanthines with different length of this aliphatic side chain were synthesized and their capability to depress MDR was tested. The results indicated that the position of carbonyl group plays a crucial role for the ability of the derivative to depress MDR of L 121 ONCR cells. (authors)

17

Modulation of P-Glycoprotein Mediated Multidrug Resistance (Mdr in Cancer Using Chemosensitizers.  

Directory of Open Access Journals (Sweden)

Full Text Available Multidrug resistance (MDR is one of the main obstacles in the chemotherapy of cancer. MDR is associated with the over expression of P-glycoprotein (P-gp, resulting in increased efflux of chemotherapy from cancer cells. Inhibiting P-gp as a method to reverse MDR in cancer patients has been studied extensively, but the results have generally been disappointing. First-generation agents were limited by unacceptable toxicity, whereas second-generation agents had bettertolerability but were confounded by unpredictable pharmacokinetic interactions and interactions with other transporter proteins. Third-generation inhibitors have high potency and specificity for P-gp. Furthermore, pharmacokinetic studies to date have shown no appreciable impact on drug metabolism and no clinically significant drug interactions with common chemotherapy agents. Third-generation P-gp inhibitors have shown promise in clinical trials. The continued development of these agents may establish the true therapeutic potential of P-gp-mediated MDR reversal.

Velingkar V.S

2010-03-01

18

A new method for a quantitative assessment of P-glycoprotein-related multidrug resistance in tumour cells.  

OpenAIRE

A rapid, functional and quantitative diagnostic method for the estimation of the P-glycoprotein (P-gp)-dependent multidrug resistance is required in the clinical treatment of human tumours, as chemotherapy protocols and resistance-reversing agents could be applied accordingly. In the present work, by using a calcein accumulation method in combination with immunorecognition and drug-resistance studies, a new method is described for the quantitative estimation of the expression and function of ...

Homolya, L.; Hollo?, M.; Mu?ller, M.; Mechetner, E. B.; Sarkadi, B.

1996-01-01

19

Directed evolution of P-glycoprotein cysteines reveals site-specific, non-conservative substitutions that preserve multidrug resistance  

OpenAIRE

Pgp (P-glycoprotein) is a prototype ABC (ATP-binding-cassette) transporter involved in multidrug resistance of cancer. We used directed evolution to replace six cytoplasmic Cys (cysteine) residues in Pgp with all 20 standard amino acids and selected for active mutants. From a pool of 75000 transformants for each block of three Cys, we identified multiple mutants that preserved drug resistance and yeast mating activity. The most frequent substitutions were glycine and serine for Cys427 (24 and...

Douglas J. Swartz; Leo Mok; Sri K. Botta; Anukriti Singh; Guillermo A. Altenberg; Ina L. Urbatsch

2014-01-01

20

Acridones circumvent P-glycoprotein-associated multidrug resistance (MDR) in cancer cells.  

Science.gov (United States)

Multidrug resistance (MDR) mediated by overexpression of MDR1 P-glycoprotein (P-gp) is one of the best characterized transporter-mediated barriers to successful chemotherapy in cancer patients. Chemosensitizers are the agents that increase the sensitivity of multidrug-resistant cells to the toxic influence of previously less effective drugs. In an attempt to find such vital chemosensitizers, a series of N(10)-substituted-2-chloroacridone analogous (1-17) have been synthesized. Compound 1 was prepared by the Ullmann condensation of o-chlorobenzoic acid and p-chloroaniline followed by cyclization. The N-(omega-chloroalkyl) analogues were found to undergo iodide catalyzed nucleophilic substitution reaction with secondary amines and the resultant products were characterized by spectral methods. The lipophilicity expressed in log(10)P and pK(a) of compounds has been determined. All compounds were examined for their ability to increase the uptake of vinblastine (VLB) in MDR KBCh(R)-8-5 cells and the results showed that the compounds 6, 8, 11-14, 16, and 17 at their respective IC(50) concentrations caused a 1.0- to 1.7-fold greater accumulation of VLB than did a similar concentration of the standard modulator, verapamil (VRP). Results of the efflux experiment showed that VRP and each of the modulators significantly inhibited the efflux of VLB, suggesting that they may be competitors for P-gp. All modulators effectively competing with [(3)H]azidopine for binding to P-gp pointed out this transport membrane protein as their likely site of action. Compounds at IC(10) were evaluated for their efficacy to modulate the cytotoxicity of VLB and the results showed that modulators 11, 13, 14, 16, and 17 were able to completely reverse the 25-fold resistance of KBCh(R)-8-5 cells to VLB. Examination of the relationship between lipophilicity and antagonism of MDR showed a reasonable correlation suggesting that hydrophobicity is one of the determinants of potency for anti-MDR activity of 2-chloroacridones. The results allowed us to draw preliminary conclusions about structural features of 2-chloroacridones important for MDR modulation. PMID:17933543

Gopinath, Vadiraj S; Thimmaiah, Padma; Thimmaiah, Kuntebommanahalli N

2008-01-01

21

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

Energy Technology Data Exchange (ETDEWEB)

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 {yields} 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 {yields} 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.

Safa, A.R.; Stern, R.K.; Choi, Kyunghee; Agresti, M.; Tamai, Ikumi; Mehta, N.D.; Roninson, I.B. (Univ. of Chicago, IL (USA))

1990-09-01

22

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

23

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

24

In vivo and in vitro multitracer analyses of P-glycoprotein expression-related multidrug resistance  

International Nuclear Information System (INIS)

P-glycoprotein (Pgp) is an ABC (ATP binding cassette) transporter that is often overexpressed in tumours, contributing significantly to their multidrug resistance. In this study, we explored whether the radiotracers used in tumour diagnostics can be used for in vivo visualisation of Pgp-related multidrug resistance. We also examined the effects of different Pgp modulators on the accumulation of these radioligands in tumours with or without Pgp expression. In a SCID BC-17 mouse model, cells of the drug-sensitive KB-3-1 (MDR-) and the KB-V1 Pgp-expressing (MDR+) human epidermoid carcinoma cell lines were inoculated to yield tumours in opposite flanks. For in vivo scintigraphic (biodistribution) and positron emission tomography (PET) examinations, the mice were injected with technetium-99m hexakis-2-methoxybutylisonitrile (99mTc-MIBI), carbon-11 labelled methionine and fluorine-18 fluoro-2-deoxy-d-glucose (18FDG). For validation, in vitro cell studies with 99mTc-MIBI,99mTc-tetrofosmin, [11C]methionine and 18FDG were carried out using a gamma counter. The expression and function of the MDR product were proved by immunohistochemistry and spectrofluorimetry. 99mTc-MIBI uptake was significantly lower in KB-V1 cells as compared with KB-3-1-derived tumours in vivo (Pgp+/Pgp- =0.61±0.13; P+/Pgp- =0.08±0.01p+/Pgp- =0.08±0.01; P99mTc-MIBI uptake in the Pgp+ cells, while verapamil failed to modify it. 18FDG uptake was significantly higher in KB-V1 tumours (Pgp+/Pgp- =1.36±0.05; P+/Pgp-=1.52 ±0.12; P + and MDR - cell lines, verapamil significantly increased it. When the animals were treated with verapamil, the ratio of 99mTc-MIBI uptake in the MDR + tumours to that in the MDR - tumours decreased to 0.38 ±0.05 (P 18FDG uptake increased to 2.1 ±0.3 (P 11C]methionine uptake in the MDR + and MDR - tumours and cell lines, nor was [ 11C]methionine accumulation modified by cyclosporin A. Parallel administration of 18FDG and 99mTc-MIBI combined with verapamil treatment seems to be a good candidate as a non-invasive marker for the diagnosis of MDR-related Pgp expression in tumours. (orig.)

25

Effects of chemosensitizer on 99Tcm-MIBI uptake of P-glycoprotein induced multidrug-resistant carcinoma cells  

International Nuclear Information System (INIS)

Objective: To observe the changes of 99Tcm-methoxyisobutylisonitrile (MIBI) uptake kinetics and P-glycoprotein levels after using verapamil in multidrug-resistant (MDR) human breast cells MCF-7/Adr, and to establish a method to evaluate the effects of chemosensitizer on P-glycoprotein using 99Tcm-MIBI. Methods: MDR breast carcinoma cells, MCF-7/Adr, were incubated at 37 degree C. 1)Verapamil (10?mol/L), a chemosensitizer, was added into cell culture medium used for verapamil group, while for control group, the same quotient of DMEM. Cells were harvested after 2 h incubation with 99Tcm-MIBI. 2)Verapamil (10 ?mol/L) was added into cell culture medium for verapamil group and incubated for 20, 40, 60, 80 min, 8, 24, 48 and 72 h respectively. Cells were harvested after 2 h incubation with 99Tcm-MIBI. The radioactivity and P-glycoprotein expression levels were determined. Results: 1) After 2 h incubation with verapamil the 99Tcm-MIBI uptake was remarkably higher in verapamil group than in control group (t=2.33, P0.05). 2) In verapamil group, 99Tcm-MIBI uptake increased with incubation time prolonging (F=58.2, P99Tcm-MIBI uptake negatively correlated to the P-glycopre negatively correlated to the P-glycoprotein expression levels (r=- 0.73, P99Tcm-MIBI accumulation and P-glycoprotein levels (r=0.16, P>0.05). Conclusion: Chemosensitizers may impact the cellular uptake of 99Tcm-MIBI in P-glycoprotein over-expressing MDR tumor cells

26

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

27

In vivo and in vitro multitracer analyses of P-glycoprotein expression-related multidrug resistance  

Energy Technology Data Exchange (ETDEWEB)

P-glycoprotein (Pgp) is an ABC (ATP binding cassette) transporter that is often overexpressed in tumours, contributing significantly to their multidrug resistance. In this study, we explored whether the radiotracers used in tumour diagnostics can be used for in vivo visualisation of Pgp-related multidrug resistance. We also examined the effects of different Pgp modulators on the accumulation of these radioligands in tumours with or without Pgp expression. In a SCID BC-17 mouse model, cells of the drug-sensitive KB-3-1 (MDR{sup -}) and the KB-V1 Pgp-expressing (MDR{sup +}) human epidermoid carcinoma cell lines were inoculated to yield tumours in opposite flanks. For in vivo scintigraphic (biodistribution) and positron emission tomography (PET) examinations, the mice were injected with technetium-99m hexakis-2-methoxybutylisonitrile ({sup 99m}Tc-MIBI), carbon-11 labelled methionine and fluorine-18 fluoro-2-deoxy-d-glucose ({sup 18}FDG). For validation, in vitro cell studies with {sup 99m}Tc-MIBI,{sup 99m}Tc-tetrofosmin, [{sup 11}C]methionine and {sup 18}FDG were carried out using a gamma counter. The expression and function of the MDR product were proved by immunohistochemistry and spectrofluorimetry. {sup 99m}Tc-MIBI uptake was significantly lower in KB-V1 cells as compared with KB-3-1-derived tumours in vivo (Pgp{sup +}/Pgp{sup -} =0.61{+-}0.13; P<0.01) and cells in vitro (Pgp{sup +}/Pgp{sup -} =0.08{+-}0.01; P<0.001).Cyclosporin A reversed {sup 99m}Tc-MIBI uptake in the Pgp+ cells, while verapamil failed to modify it. {sup 18}FDG uptake was significantly higher in KB-V1 tumours (Pgp{sup +}/Pgp{sup -} =1.36{+-}0.05; P<0.01) and cells (Pgp{sup +}/Pgp{sup -}=1.52 {+-}0.12; P <0.001). Whereas cyclosporin A eliminated the difference between FDG uptake in MDR {sup +} and MDR {sup -} cell lines, verapamil significantly increased it. When the animals were treated with verapamil, the ratio of {sup 99m}Tc-MIBI uptake in the MDR {sup +} tumours to that in the MDR {sup -} tumours decreased to 0.38 {+-}0.05 (P <0.01), while the ratio of {sup 18}FDG uptake increased to 2.1 {+-}0.3 (P <0.001). There were no significant differences in the [ {sup 11}C]methionine uptake in the MDR {sup +} and MDR {sup -} tumours and cell lines, nor was [ {sup 11}C]methionine accumulation modified by cyclosporin A. Parallel administration of {sup 18}FDG and {sup 99m}Tc-MIBI combined with verapamil treatment seems to be a good candidate as a non-invasive marker for the diagnosis of MDR-related Pgp expression in tumours. (orig.)

Marian, Terez; Balkay, Laszlo; Mikecz, Pal; Tron, Lajos [PET Center, University of Debrecen (Hungary); Szabo, Gabor; Goda, Katalin; Nagy, Henrietta; Krasznai, Zoltan [Department of Biophysics and Cell Biology, University of Debrecen, Nagyerdei krt 98, 4012, Debrecen (Hungary); Szincsak, Nora; Juhasz, Istvan [Department of Dermatology, University of Debrecen (Hungary); Galuska, Laszlo [Center of Nuclear Medicine, University of Debrecen (Hungary)

2003-08-01

28

Inhibition of N-linked glycosylation of P-glycoprotein by tunicamycin results in a reduced multidrug resistance phenotype.  

OpenAIRE

Characterisation of altered glycosylation of P-glycoprotein (P-gp) found associated with the absence of a multidrug resistance (MDR) phenotype in cell lines prompted an investigation to assess the role of post-translational processing in establishing P-gp efflux pump functionally. The clone A cell line used in this study displays a strong MDR phenotype mediated by high constitutive levels of expression of P-gp. Incubation of clone A cells with tunicamycin for different periods resulted in a t...

Kramer, R.; Weber, T. K.; Arceci, R.; Ramchurren, N.; Kastrinakis, W. V.; Steele, G.; Summerhayes, I. C.

1995-01-01

29

Multidrug resistance 1 gene (P-glycoprotein 170): an important determinant in gastrointestinal disease?  

OpenAIRE

The interface between luminal contents and intestinal epithelium constitutes the largest area of interaction between the host and the environment. There is now strong evidence that the gene product of the multidrug resistant pump (MDR) plays a critical role in host-bacterial interactions in the gastrointestinal tract and maintenance of intestinal homeostasis. This review highlights the efflux mechanism in the intestinal epithelium which is mediated by the multidrug resistant pump, also known ...

Ho, G-t; Moodie, F. M.; Satsangi, J

2003-01-01

30

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

OpenAIRE

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...

Safa, A. R.

1988-01-01

31

Intercellular transfer of P-glycoprotein mediates acquired multidrug resistance in tumor cells  

OpenAIRE

The overexpression of P-glycoprotein (P-gp) causes resistance to chemotherapy in many tumor types. Here, we report intercellular transfer of functional P-gp from P-gp-positive to P-gp-negative cells in vitro and in vivo. The expression of acquired P-gp is transient in isolated cells but persists in the presence of P-gp-positive cells or under the selective pressure of colchicine. The intercellular transfer of functional P-gp occurs between different tumor cell types and results in increased d...

Levchenko, Andre; Mehta, Bipin M.; Niu, Xinle; Kang, Grace; Villafania, Liliana; Way, Denise; Polycarpe, Dolores; Sadelain, Michel; Larson, Steven M.

2005-01-01

32

8-Prenylnaringenin is an inhibitor of multidrug resistance-associated transporters, P-glycoprotein and MRP1.  

Science.gov (United States)

Flavonoids with hydrophobic e.g. prenyl substituents might constitute the promising candidates for multidrug resistance (MDR) reversal agents. The interaction of 8-prenylnaringenin (8-isopentenylnaringenin), a potent phytoestrogen isolated from common hop (Humulus lupulus), with two multidrug resistance-associated ABC transporters of cancer cells, P-glycoprotein and MRP1, has been studied for the first time. Functional test based on the transport of fluorescent substrate BCECF revealed that the flavonoid strongly inhibited MRP1 transport activity in human erythrocytes (IC(50)=5.76+/-1.80muM). Expression of MDR-related transporters in drug-sensitive (LoVo) and doxorubicin-resistant (LoVo/Dx) human colon adenocarcinoma cell lines was characterized by RT-PCR and immunochemical methods and elevated expression of P-glycoprotein in resistant cells was found to be the main difference between these two cell lines. By means of flow cytometry it was shown that 8-prenylnaringenin significantly increased the accumulation of rhodamine 123 in LoVo/Dx cells. Doxorubicin accumulation in both LoVo and LoVo/Dx cells observed by confocal microscopy was also altered in the presence of 8-prenylnaringenin. However, the presence of the studied compound did not increase doxorubicin cytotoxicity to LoVo/Dx cells. It was concluded that 8-prenylnaringenin was not able to modulate MDR in human adenocarcinoma cell line in spite of the ability to inhibit both P-glycoprotein and MRP1 activities. To our best knowledge, this is the first report of 8-prenylnaringenin interaction with clinically important ABC transporters. PMID:20633549

Weso?owska, Olga; Wi?niewski, Jerzy; Sroda, Kamila; Krawczenko, Agnieszka; Bielawska-Pohl, Aleksandra; Paprocka, Maria; Du?, Danuta; Michalak, Krystyna

2010-10-10

33

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

34

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

35

Carboxymethylcellulose-based and docetaxel-loaded nanoparticles circumvent P-glycoprotein-mediated multidrug resistance.  

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Taxanes are a class of anticancer agents with a broad spectrum and have been widely used to treat a variety of cancer. However, its long-term use has been hampered by accumulating toxicity and development of drug resistance. The most extensively reported mechanism of resistance is the overexpression of P-glycoprotein (Pgp). We have developed a PEGylated carboxymethylcellulose conjugate of docetaxel (Cellax), which condenses into ?120 nm nanoparticles. Here we demonstrated that Cellax therapy did not upregulate Pgp expression in MDA-MB-231 and EMT-6 breast tumor cells, whereas a significant increase in Pgp expression was measured with native docetaxel (DTX) treatment. Treatment with DTX led to 4-7-fold higher Pgp mRNA expression and 2-fold higher Pgp protein expression compared with Cellax treatment in the in vitro and in vivo system, respectively. Cellax also exhibited significantly increased efficacy compared with that of DTX in a taxane-resistant breast tumor model. Against the highly Pgp expressing EMT6/AR1 cells, Cellax exhibited a 6.5 times lower IC50 compared with that of native DTX, and in the in vivo model, Cellax exhibited 90% tumor growth inhibition, while native DTX had no significant antitumor activity. PMID:24564177

Roy, Aniruddha; Murakami, Mami; Ernsting, Mark J; Hoang, Bryan; Undzys, Elijus; Li, Shyh-Dar

2014-08-01

36

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

37

Astragaloside IV reduces the expression level of P-glycoprotein in multidrug-resistant human hepatic cancer cell lines  

Science.gov (United States)

Astragaloside is a saponin widely used in traditional Chinese medicine and has been reported to be a potent multidrug resistance (MDR) reversal agent. The present study investigated the role of astragaloside IV (ASIV) in the regulation of P-glycoprotein (P-gp, encoded by the mdr1 gene) and its effect on the reversal of MDR. The activity of ASIV was evaluated using human hepatic cancer cells Bel-7402 and the corresponding 5-fluorouracil (5-FU) resistant cells Bel-7402/FU. ASIV (0.08 mg/ml) potentiated the cytotoxicity of 5-FU which was demonstrated using the MTT assay on Bel-7402/FU cells. ASIV reduced the expression of P-gp as was revealed by immunocytochemistry. Accumulation and efflux studies with the P-gp substrate, rhodamine 123 (Rh123), demonstrated that ASIV inhibited P-gp-mediated drug efflux. Furthermore, it was demonstrated that ASIV enhanced the drug accumulation of 5-FU using a high performance liquid chromatography (HPLC) assay for drug resistant cells. Furthermore, ASIV may downregulate the expression of P-gp, which was examined using western blot analysis and polymerase chain reaction. In conclusion, the results of the present study indicated that ASIV reverses the drug resistance of Bel-7402/FU cells by downregulating the expression of mdr1. ASIV may represent a potent modulator of P-gp-mediated MDR in hepatic cancer therapy. PMID:24676670

WANG, PEI-PEI; XU, DU-JUAN; HUANG, CAN; WANG, WEI-PING; XU, WEN-KE

2014-01-01

38

Astragaloside ? reduces the expression level of P-glycoprotein in multidrug-resistant human hepatic cancer cell lines.  

Science.gov (United States)

Astragaloside is a saponin widely used in traditional Chinese medicine and has been reported to be a potent multidrug resistance (MDR) reversal agent. The present study investigated the role of astragaloside ? (ASIV) in the regulation of P-glycoprotein (P-gp, encoded by the mdr1 gene) and its effect on the reversal of MDR. The activity of ASIV was evaluated using human hepatic cancer cells Bel-7402 and the corresponding 5-fluorouracil (5-FU) resistant cells Bel-7402/FU. ASIV (0.08 mg/ml) potentiated the cytotoxicity of 5-FU which was demonstrated using the MTT assay on Bel-7402/FU cells. ASIV reduced the expression of P-gp as was revealed by immunocytochemistry. Accumulation and efflux studies with the P-gp substrate, rhodamine 123 (Rh123), demonstrated that ASIV inhibited P-gp-mediated drug efflux. Furthermore, it was demonstrated that AS? enhanced the drug accumulation of 5-FU using a high performance liquid chromatography (HPLC) assay for drug resistant cells. Furthermore, ASIV may downregulate the expression of P-gp, which was examined using western blot analysis and polymerase chain reaction. In conclusion, the results of the present study indicated that ASIV reverses the drug resistance of Bel-7402/FU cells by downregulating the expression of mdr1. ASIV may represent a potent modulator of P-gp-mediated MDR in hepatic cancer therapy. PMID:24676670

Wang, Pei-Pei; Xu, Du-Juan; Huang, Can; Wang, Wei-Ping; Xu, Wen-Ke

2014-06-01

39

Compounds from Chinese herbal medicines as reversal agents for P-glycoprotein-mediated multidrug resistance in tumours.  

Science.gov (United States)

Multidrug resistance (MDR) is a major obstacle to successful cancer chemotherapy. One of the main underlying mechanisms of this resistance is the over-expression of P-glycoprotein (P-gp), an ATP-dependent transmembrane transporter protein encoded by the MDR1 gene. P-gp might transport anti-cancer drugs out of cancer cells and decrease effective intracellular drug concentrations. An effective approach to overcome MDR is to inhibit the function of P-gp or its expression on the surface of cancer cells. Thus, application of MDR reversal agents can be seen as a potentially important means by which to overcome the clinical drug resistance of tumour cells and improve the efficacy of chemotherapy. Recently, research efforts worldwide have focused on reversal mechanisms for MDR and on the identification of reversal agents. Chinese scholars have performed a great deal of exploratory work by screening for efficacy and low toxicity in drug resistance reversal compounds. These compounds may provide more lead compounds with greater activity, leading to the development of more effective therapies for MDR cancer cells. In this review, the function and efficiency of novel compounds derived from traditional Chinese medicines are described. PMID:24643703

Li, C; Sun, B-Q; Gai, X-D

2014-07-01

40

Membrane transport of camptothecin: facilitation by human P-glycoprotein (ABCB1) and multidrug resistance protein 2 (ABCC2)  

OpenAIRE

Abstract Background The purpose of the present study was to continue the investigation of the membrane transport mechanisms of 20-(S)-camptothecin (CPT) in order to understand the possible role of membrane transporters on its oral bioavailability and disposition. Methods The intestinal transport kinetics of CPT were characterized using Caco-2 cells, MDCKII wild-type cells and MDCKII cells transfected with human P-glycoprotein (PGP) (ABCB1) or human multidrug res...

Lee Sung-Hack; Paranjpe Pankaj V; Guo Ailan; Luo Feng R; Lalloo Anita K; Vyas Viral; Rubin Eric; Sinko Patrick J

2004-01-01

41

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)

42

Modulation of the multidrug resistance P-glycoprotein: Detection with technetium-99m-sestamibi in vivo  

Energy Technology Data Exchange (ETDEWEB)

Overexpression of the multidrug resistance (MDR1) P-glycoprotein (Pgp) has been documented in nearly all forms of human cancers and increased levels of Pgp in some tumors correlate with poor response to treatment. Technetium-99m-sestamibi has recently been validated as a Pgp transport substrate. Pgp is also normally expressed along the biliary canalicular surface of hepatocytes and the luminal side of proximal tubule cells in the kidney, while not expressed in heart. Focused on these organs with known Pgp status, we present the findings on {sup 99m}Tc-sestamibi showed normal, prompt clearance of the radiotracer from the liver and kidneys relative to the heart. After administration of the Pgp modulator, {sup 99m}Tc-sestamibi was selectively retained in the liver and kidneys. Hepatobiliary and renal clearance of {sup 99m}Tc-sestamibi are Pgp-mediated, and inhibition of Pgp transport in these organs can be successfully imaged using {sup 99m}Tc-sestamibi in patients. Similar results might be expected with this and related radiopharmaceuticals for functional imaging of Pgp transport and modulation in tumors. 34 refs., 2 figs.

Luker, G.D.; Fracasso, P.M.; Dobkin, J.; Piwnica-Worms, D. [Washington Univ. School of Medicine, St. Louis, MO (United States)

1997-03-01

43

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

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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

44

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

DEFF Research Database (Denmark)

PURPOSE: To characterize irradiated murine tumor cells with respect to drug resistance, drug kinetics, and ATPase activity, and to evaluate the possible role of P-glycoprotein (PGP) and murine multidrug resistance associated protein (Mrp1) in the drug-resistant phenotype of these cells. METHODS AND MATERIALS: Sensitive Ehrlich ascites tumor cells (EHR2) were in vitro exposed to fractionated irradiation (60 Gy). Western blot analysis was performed for determination of PGP and Mrp1, reverse transcriptase-polymerase chain reaction (RT-PCR) for determination of mdr1a + b mRNA, and semiquantitative RT-PCR for Mrp1 mRNA. The clonogenic assay was applied to investigate sensitivity, whereas the steady-state drug accumulation of daunorubicin (DNR), 3H-vincristine (VCR), and 3H-etoposide (VP16) was measured by spectrofluorometry and scintillation counting, respectively. For determining of ATPase activity, the release of inorganic phosphate from ATP was quantified using a colorimetric method. RESULTS: Compared with EHR2, the irradiated cell line EHR2/irr showed increased expression of PGP (threefold), Mrp1 (eightfold), and Mrp1 mRNA (sixfold), and a slight reduction of mdr1b mRNA, whereas mdr1a was present in EHR2 but could not be detected in EHR2/irr. EHR2/irr developed sixfold resistance to VP16, twofold resistance to vincristine, but remained sensitive to DNR. Addition of the PGP inhibitor, verapamil (VER) or depletion of glutathione by buthionine sulfoximine (BSO) partly reversed the resistance in EHR2/irr. In EHR2/irr, the steady-state accumulation of 3H-VCR and 3H-VP16 was significantly decreased as compared with EHR2, whereas the accumulation of DNR was unchanged. The ATPase activity of plasma membrane vesicles prepared from EHR2/irr cells was similar to that of wild-type EHR2 cells. The ATPase activity was neither stimulated by vinblastine nor VER. CONCLUSION: Irradiation induced a multidrug-resistant phenotype in sensitive tumor cells. This phenotype was characterized by increased expression of Mrp1 mRNA, Mrp1, and PGP but decreased expression of mdr1a + b mRNA. The influence of irradiation on PGP and Mrp1 expression seemed to be different.

Nielsen, D; Maare, C

2001-01-01

45

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

International Nuclear Information System (INIS)

Purpose: To characterize irradiated murine tumor cells with respect to drug resistance, drug kinetics, and ATPase activity, and to evaluate the possible role of P-glycoprotein (PGP) and murine multidrug resistance associated protein (Mrp1) in the drug-resistant phenotype of these cells. Methods and Materials: Sensitive Ehrlich ascites tumor cells (EHR2) were in vitro exposed to fractionated irradiation (60 Gy). Western blot analysis was performed for determination of PGP and Mrp1, reverse transcriptase-polymerase chain reaction (RT-PCR) for determination of mdr1a + b mRNA, and semiquantitative RT-PCR for Mrp1 mRNA. The clonogenic assay was applied to investigate sensitivity, whereas the steady-state drug accumulation of daunorubicin (DNR), 3H-vincristine (VCR), and 3H-etoposide (VP16) was measured by spectrofluorometry and scintillation counting, respectively. For determining of ATPase activity, the release of inorganic phosphate from ATP was quantified using a colorimetric method. Results: Compared with EHR2, the irradiated cell line EHR2/irr showed increased expression of PGP (threefold), Mrp1 (eightfold), and Mrp1 mRNA (sixfold), and a slight reduction of mdr1b mRNA, whereas mdr1a was present in EHR2 but could not be detected in EHR2/irr. EHR2/irr developed sixfold resistance to VP16, twofold resistance to vincristine, but remained sensitive to DNR. Addition of the PGP inhibitor, verapamil (VER) or depletion of glutathione by buthionine sulfoxletion of glutathione by buthionine sulfoximine (BSO) partly reversed the resistance in EHR2/irr. In EHR2/irr, the steady-state accumulation of 3H-VCR and 3H-VP16 was significantly decreased as compared with EHR2, whereas the accumulation of DNR was unchanged. The ATPase activity of plasma membrane vesicles prepared from EHR2/irr cells was similar to that of wild-type EHR2 cells. The ATPase activity was neither stimulated by vinblastine nor VER. Conclusion: Irradiation induced a multidrug-resistant phenotype in sensitive tumor cells. This phenotype was characterized by increased expression of Mrp1 mRNA, Mrp1, and PGP but decreased expression of mdr1a + b mRNA. The influence of irradiation on PGP and Mrp1 expression seemed to be different

46

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

OpenAIRE

Abstract 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...

Webb Glenn; Boulangé-Lecomte Céline; Magal Pierre; Pasquier Jennifer; Le Foll Frank

2011-01-01

47

In vivo imaging and specific targeting of P-glycoprotein expression in multidrug resistant nude mice xenografts with [125I]MRK-16 monoclonal antibody  

International Nuclear Information System (INIS)

Multidrug resistance (MDR) in tumors is associated with P-glycoprotein (Pgp) expression. In vivo quantitation of Pgp may allow MDR to be evaluated noninvasively prior to treatment planning. The purpose of this study was to radiolabel MRK-16, a monoclonal antibody that targets an external epitope of P-glycoprotein, and perform in vivo quantitation of P-glycoprotein in a MDR xenograft nude mouse model. MRK-16 was labeled with 125I by the iodogen method, with subsequent purification by size exclusion chromatography. Groups of 10 Balb/c mice were each xenografted with colchicine-resistant or -sensitive neuroblastoma cell lines, respectively. Whole body clearance and tumor uptake over time was quantitated by gamma camera imaging, and biodistribution studies were performed with [125]MRK-16 and an isotype matched control antibody, A33. Quantitative autoradiography and immunohistochemistry analysis of tumors was also evaluated to confirm specific targeting of [125I]MRK-16. Peak tumor uptake was at 2-3 days post-injection, and was significantly greater in resistance compared to sensitive tumors (mean % injected dose/g ± SD) (18.76 ± 2.94 vs 10.93 ± 0.96; p 125I]MRK-16 was confirmed by comparison to [131I]A33 in biodistribution studies, and localized to cellular components of tissue stroma by colar components of tissue stroma by comparison of histologic and autoradiographic sections of sensitive and resistant tumors. Immunoblot analysis demonstrated a 4.5-fold difference in P-glycoprotein expression between sensitive and resistant cell lines without colchicine selective pressure. We conclude that in vivo quantitation of P-glycoprotein in MDR tumors can be performed with [125I]MRK-16. These findings suggest a potential clinical application for radiolabeled MRK-16 in the in vivo evaluation of multidrug resistance in tumors

48

Understanding polyspecificity within the substrate-binding cavity of the human multidrug resistance P-glycoprotein.  

Science.gov (United States)

Human P-glycoprotein (P-gp) controls drugs bioavailability by pumping structurally unrelated drugs out of cells. The X-ray structure of the mouse P-gp ortholog has been solved, with two SSS enantiomers or one RRR enantiomer of the selenohexapeptide inhibitor QZ59, found within the putative drug-binding pocket (Aller SG, Yu J, Ward A, Weng Y, Chittaboina S, Zhuo R, Harrell PM, Trinh YT, Zhang Q, Urbatsch IL et al. (2009). Science 323, 1718-1722). This offered the first opportunity to localize the well-known H and R drug-binding sites with respect to the QZ59 inhibition mechanisms of Hoechst 33342 and daunorubicin transports, characterized here in cellulo. We found that QZ59-SSS competes efficiently with both substrates, with K(I,app) values of 0.15 and 0.3 ?M, which are 13 and 2 times lower, respectively, than the corresponding K(m,app) values. In contrast, QZ59-RRR non-competitively inhibited daunorubicin transport with moderate efficacy (K(I,app) = 1.9 ?M); it also displayed a mixed-type inhibition of the Hoechst 33342 transport, resulting from a main non-competitive tendency (K(i2,app) = 1.6 ?M) and a limited competitive tendency (K(i1,app) = 5 ?M). These results suggest a positional overlap of QZ59 and drugs binding sites: full for the SSS enantiomer and partial for the RRR enantiomer. Crystal structure analysis suggests that the H site overlaps both QZ59-SSS locations while the R site overlaps the most embedded location. PMID:24219411

Martinez, Lorena; Arnaud, Ophélie; Henin, Emilie; Tao, Houchao; Chaptal, Vincent; Doshi, Rupak; Andrieu, Thibault; Dussurgey, Sébastien; Tod, Michel; Di Pietro, Attilio; Zhang, Qinghai; Chang, Geoffrey; Falson, Pierre

2014-02-01

49

Directed evolution of P-glycoprotein cysteines reveals site-specific, non-conservative substitutions that preserve multidrug resistance  

Directory of Open Access Journals (Sweden)

Full Text Available Pgp (P-glycoprotein is a prototype ABC (ATP-binding-cassette transporter involved in multidrug resistance of cancer. We used directed evolution to replace six cytoplasmic Cys (cysteine residues in Pgp with all 20 standard amino acids and selected for active mutants. From a pool of 75000 transformants for each block of three Cys, we identified multiple mutants that preserved drug resistance and yeast mating activity. The most frequent substitutions were glycine and serine for Cys427 (24 and 20%, respectively and Cys1070 (37 and 25% of the Walker A motifs in the NBDs (nucleotide-binding domains, Cys1223 in NBD2 (25 and 8% and Cys638 in the linker region (24 and 16%, whereas close-by Cys669 tolerated glycine (16% and alanine (14%, but not serine (absent. Cys1121 in NBD2 showed a clear preference for positively charged arginine (38% suggesting a salt bridge with Glu269 in the ICL2 (intracellular loop 2 may stabilize domain interactions. In contrast, three Cys residues in transmembrane ?-helices could be successfully replaced by alanine. The resulting CL (Cys-less Pgp was fully active in yeast cells, and purified proteins displayed drug-stimulated ATPase activities indistinguishable from WT (wild-type Pgp. Overall, directed evolution identified site-specific, non-conservative Cys substitutions that allowed building of a robust CL Pgp, an invaluable new tool for future functional and structural studies, and that may guide the construction of other CL proteins where alanine and serine have proven unsuccessful.

Douglas J. Swartz

2014-06-01

50

Membrane transport of camptothecin: facilitation by human P-glycoprotein (ABCB1 and multidrug resistance protein 2 (ABCC2  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background The purpose of the present study was to continue the investigation of the membrane transport mechanisms of 20-(S-camptothecin (CPT in order to understand the possible role of membrane transporters on its oral bioavailability and disposition. Methods The intestinal transport kinetics of CPT were characterized using Caco-2 cells, MDCKII wild-type cells and MDCKII cells transfected with human P-glycoprotein (PGP (ABCB1 or human multidrug resistance protein 2 (MRP2 (ABCC2. The effects of drug concentration, inhibitors and temperature on CPT directional permeability were determined. Results The absorptive (apical to basolateral and secretory (basolateral to apical permeabilities of CPT were found to be saturable. Reduced secretory CPT permeabilities with decreasing temperatures suggests the involvement of an active, transporter-mediated secretory pathway. In the presence of etoposide, the CPT secretory permeability decreased 25.6%. However, inhibition was greater in the presence of PGP and of the breast cancer resistant protein inhibitor, GF120918 (52.5%. The involvement of additional secretory transporters was suggested since the basolateral to apical permeability of CPT was not further reduced in the presence of increasing concentrations of GF120918. To investigate the involvement of specific apically-located secretory membrane transporters, CPT transport studies were conducted using MDCKII/PGP cells and MDCKII/MRP2 cells. CPT carrier-mediated permeability was approximately twofold greater in MDCKII/PGP cells and MDCKII/MRP2 cells than in MDCKII/wild-type cells, while the apparent Km values were comparable in all three cell lines. The efflux ratio of CPT in MDCKII/PGP in the presence of 0.2 ?M GF120918 was not completely reversed (3.36 to 1.49. However, the decrease in the efflux ratio of CPT in MDCKII/MRP2 cells (2.31 to 1.03 suggests that CPT efflux was completely inhibited by MK571, a potent inhibitor of the Multidrug Resistance Protein transporter family. Conclusions The current results provide evidence that PGP and MRP2 mediate the secretory transport of CPT in vitro. However, the involvement of other transporters cannot be ruled out based on these studies. Since these transporters are expressed in the intestine, liver and kidney variations in their expression levels and/or regulation may be responsible for the erratic oral absorption and biliary excretion of CPT observed in human subjects.

Lee Sung-Hack

2004-05-01

51

Technetium-99m methoxyisobutylisonitrile imaging for parathyroid adenoma: relationship to P-glycoprotein or multidrug resistance-related protein expression  

International Nuclear Information System (INIS)

Gland size has been reported to have a major influence on localisation of parathyroid adenomas by technetium-99m methoxyisobutylisonitrile (99mTc-MIBI) imaging. It has also been suggested that P-glycoprotein (Pgp) expression in parathyroid adenomas may influence localisation because false negative studies have been reported with large tumours and true positives with very small tumours. Therefore, the purpose of this study was to retrospectively evaluate the relationship between 99mTc-MIBI parathyroid imaging results and Pgp or multidrug resistance-related protein (MRP) expression in parathyroid adenomas. Before surgery, 47 patients with large parathyroid adenomas (larger than 1.5 g) underwent early and delayed parathyroid imaging, 10 min and 2 h after intravenous injection of 99mTc-MIBI. Immunohistochemical analyses (IHA) were performed, using multiple non-consecutive sections of the operative specimens, to detect Pgp or MRP expression. According to the results of IHA, the 34 parathyroid adenomas were separated into four groups: (1) three adenomas positive for both Pgp and MRP expression, (2) one adenoma positive for Pgp but negative for MRP expression, (3) four adenomas negative for Pgp but positive for MRP expression and (4) 39 adenomas with negative for both Pgp and MRP expression. All 39 adenomas in group 4 could be detected by 99mTc-MIBI parathyroid imaging. None of the eight adenomas in groups 1-3 could be detected by enomas in groups 1-3 could be detected by 99mTc-MIBI parathyroid imaging (P99mTc-MIBI imaging in localising parathyroid adenomas preoperatively. (orig.)

52

Technetium-99m methoxyisobutylisonitrile imaging for parathyroid adenoma: relationship to P-glycoprotein or multidrug resistance-related protein expression  

Energy Technology Data Exchange (ETDEWEB)

Gland size has been reported to have a major influence on localisation of parathyroid adenomas by technetium-99m methoxyisobutylisonitrile ({sup 99m}Tc-MIBI) imaging. It has also been suggested that P-glycoprotein (Pgp) expression in parathyroid adenomas may influence localisation because false negative studies have been reported with large tumours and true positives with very small tumours. Therefore, the purpose of this study was to retrospectively evaluate the relationship between {sup 99m}Tc-MIBI parathyroid imaging results and Pgp or multidrug resistance-related protein (MRP) expression in parathyroid adenomas. Before surgery, 47 patients with large parathyroid adenomas (larger than 1.5 g) underwent early and delayed parathyroid imaging, 10 min and 2 h after intravenous injection of {sup 99m}Tc-MIBI. Immunohistochemical analyses (IHA) were performed, using multiple non-consecutive sections of the operative specimens, to detect Pgp or MRP expression. According to the results of IHA, the 34 parathyroid adenomas were separated into four groups: (1) three adenomas positive for both Pgp and MRP expression, (2) one adenoma positive for Pgp but negative for MRP expression, (3) four adenomas negative for Pgp but positive for MRP expression and (4) 39 adenomas with negative for both Pgp and MRP expression. All 39 adenomas in group 4 could be detected by {sup 99m}Tc-MIBI parathyroid imaging. None of the eight adenomas in groups 1-3 could be detected by {sup 99m}Tc-MIBI parathyroid imaging (P<0.05). It is concluded that not only the size of parathyroid adenomas but also significant Pgp or MRP expression limits the sensitivity of {sup 99m}Tc-MIBI imaging in localising parathyroid adenomas preoperatively. (orig.)

Kao, Albert [Departments of Nuclear Medicine and Medical Research, China Medical College Hospital, No. 2, Yuh-Der Road, Taichung 404 (Taiwan); Shiau, Yu-Chien [Department of Nuclear Medicine, Far Eastern Memorial Hospital, Institute of Biomedical Engineering, College of Electrical Engineering, National Taiwan University, Taipei (Taiwan); Tsai, Shih-Chuan [Department of Nuclear Medicine, Show-Chwan Memorial Hospital, Chunghua (Taiwan); Wang, Jhi-Joung [Department of Medical Research, Chi-Mei Medical Center, Tainan (Taiwan); Ho, Shung-Tai [School of Medicine, National Defense Medical Center, Taipe (Taiwan)

2002-08-01

53

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

54

Reversion of multidrug resistance in the P-glycoprotein-positive human pancreatic cell line (EPP85-181RDB) by introduction of a hammerhead ribozyme.  

OpenAIRE

A major problem in cytostatic treatment of many tumours is the development of multidrug resistance (MDR4). This is most often accompanied by the overexpression of a membrane transport protein, P-glycoprotein, and its encoding mRNA. In order to reverse the resistant phenotype in cell cultures, we constructed a specific hammerhead ribozyme possessing catalytic activity that cleaves the 3'-end of the GUC sequence in codon 880 of the mdr1 mRNA. We demonstrated that the constructed ribozyme is abl...

Holm, P. S.; Scanlon, K. J.; Dietel, M.

1994-01-01

55

Vanadate trapping of nucleotide at the ATP-binding sites of human multidrug resistance P-glycoprotein exposes different residues to the drug-binding site  

OpenAIRE

The human multidrug resistance P-glycoprotein uses ATP to transport a wide variety of structurally unrelated cytotoxic compounds out of the cell. In this study, we used cysteine-scanning mutagenesis and cross-linking studies to identify residues that are exposed to the drug-binding site upon vanadate trapping. In the absence of nucleotides, C222(TM4) was cross-linked to C868(TM10) and C872(TM10); C306(TM5) was cross-linked to C868(TM10), C872(TM10), C945(TM11), C982(TM12), and C984(TM12); and...

Loo, Tip W.; Clarke, David M.

2002-01-01

56

Effect of anthracycline analogs on photolabelling of p-glycoprotein by [125I]iodomycin and [3H]azidopine: relation to lipophilicity and inhibition of daunorubicin transport in multidrug resistant cells.  

OpenAIRE

Eight anthracycline analogs that have been shown to modulate multidrug resistance (Friche et al., Biochem. Pharmacol., 39, 1721-1726; 1990) were tested for their inhibitory effect on the photolabelling of P-glycoprotein. We photoaffinity labelled P-glycoprotein in daunorubicin (DNR) resistant Ehrlich ascites tumour cells (EHR2/DNR +) with a [125I]iodinated Bolton-Hunter derivative of daunorubicin ([125I]iodomycin) and with [3H]azidopine. The photolabelling of P-glycoprotein by [125I]iodomycin...

Friche, E.; Demant, E. J.; Sehested, M.; Nissen, N. I.

1993-01-01

57

Photodynamic therapy inhibits p-glycoprotein mediated multidrug resistance via JNK activation in human hepatocellular carcinoma using the photosensitizer pheophorbide a  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Multidrug resistance (MDR is frequently observed after prolonged treatment in human hepatoma with conventional anti-tumor drugs, and photodynamic therapy (PDT is a recently suggested alternative to overcome MDR. The therapeutic potential of PDT was evaluated in a multidrug resistance (MDR human hepatoma cell line R-HepG2 with photosensitizer pheophorbide a (Pa. Results Our results demonstrated that intracellular accumulation of Pa was not reduced by the overexpression of P-glycoprotein. Pa-based PDT (Pa-PDT significantly inhibited the growth of R-HepG2 cells with an IC50 value of 0.6 ?M. Mechanistic study demonstrated that genomic DNA fragmentation and phosphatidylserine externalization occurred where increase of intracellular singlet oxygen level triggers the phosphorylation of c-Jun N-terminal Kinase (JNK and leads to activation of intrinsic apoptotic caspases cascade during the Pa-PDT treatment. The cytotoxicity of Pa-PDT, accumulation of sub-G1 population, and depolarization of mitochondrial membrane could be inhibited by JNK inhibitor in the Pa-PDT treated cells. Interestingly, the Pa-PDT induced JNK activation showed inhibitory effect on MDR by the down-regulation of P-glycoprotein in R-HepG2 cells in a dose-dependent manner. In addition, significant reduction of tumor size was obtained in Pa-PDT treated R-HepG2-bearing nude mice with no significant damages in liver and heart. Conclusion In summary, our findings provided the first evidence that PDT could inhibit the MDR activity by down-regulating the expression of P-glycoprotein via JNK activation using pheophorbide a as the photosensitizer, and our work proved that Pa-PDT inhibited the growth of MDR hepatoma cells by mitochondrial-mediated apoptosis induction.

Kong Siu-Kai

2009-07-01

58

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

DEFF Research Database (Denmark)

The impact of the ABC transporters breast cancer resistance protein/mitoxantrone resistance associated transporter (BCRP/MXR), multidrug resistance-associated protein 1 (MRP1) and multidrug resistance gene-1/P-glycoprotein (MDR1/PGP) on the multidrug resistance (MDR) phenotype in chemoresistance and thermoresistance was investigated in the parental human gastric carcinoma cell line EPG85-257P, the atypical MDR subline EPG85-257RNOV, the classical MDR subline EPG85-257RDB and their thermoresistant counterparts EPG85-257P-TR, EPG85-257RNOV-TR and EPG85-257RDB-TR. Within the atypical MDR subline EPG85-257RNOV expression of BCRP/MXR and of MRP1 were clearly enhanced (vs. parental and classical MDR lines). MDR1/PGP expression was distinctly elevated in the classical MDR subline EPG85-257RDB (vs. parental and atypical MDR sublines). In all thermoresistant counterparts basal expression of BCRP/MXR, MRP1 and MDR1/PGP was increased relative to thermosensitive sublines. Although it could be shown that the overexpressedABC transporters were functionally active, however, no decreased drug accumulations of doxorubicin, mitoxantrone and rhodamine 123 were observed. Thus, expression of BCRP/MXR, MRP1 and MDR1/PGP was found to be dependent on the appropriate type of chemoresistance; correlating with a classical or atypical MDR phenotype. Within the thermoresistant variants, however, the increase in ABC transporter expression did obviously not influence the MDR phenotype.

Stein, Ulrike; Lage, Hermann

2002-01-01

59

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

60

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

Energy Technology Data Exchange (ETDEWEB)

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.

Chang, C.-S. E-mail: changcs@vghtc.gov.tw; Huang, W.-T.; Yang, S.-S.; Yeh, H.-Z.; Kao, C.-H.; Chen, G.-H

2003-02-01

61

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

62

Increased sensitivity to gemcitabine of P-glycoprotein and multidrug resistance-associated protein-overexpressing human cancer cell lines.  

OpenAIRE

0.05), respectively. P-glycoprotein and MRP1 overexpression possibly caused a cellular stress resulting in increased gemcitabine metabolism and sensitivity, while reversal of collateral gemcitabine sensitivity by verapamil also suggests a direct relation between the presence of membrane efflux pumps and gemcitabine sensitivity.

Bergman, A. M.; Pinedo, H. M.; Talianidis, I.; Veerman, G.; Loves, Wj; Wilt, C. L.; Peters, G. J.

2003-01-01

63

Apoptosis induction and modulation of P-glycoprotein mediated multidrug resistance by new macrocyclic lathyrane-type diterpenoids.  

Science.gov (United States)

The macrocyclic lathyrane diterpenes, latilagascenes D-F (1-3) and jolkinol B (4), were isolated from the methanol extract of Euphorbia lagascae, and evaluated for multidrug resistance reversing activity on mouse lymphoma cells. All compounds displayed very strong activity compared with that of the positive control, verapamil. The structure-activity relationship is discussed. The evaluation of compounds 1 and 4, and of latigascenes A-C (5-7), isolated from the same species, as apoptosis-inducers was also carried out. Compound 1 was the most active. Furthermore, in the model of combination chemotherapy, the interaction between the doxorubicine and latilagascene B (6) was studied in vitro, on human MDR1 gene transfected mouse lymphoma cells, showing that the type of interaction was synergistic. Latilagascenes D-F (1-3) are new compounds whose structures were established on the basis of spectroscopic methods, including 2D NMR experiments (COSY, HMQC, HMBC and NOESY). PMID:17035027

Duarte, Noélia; Varga, Andras; Cherepnev, Georg; Radics, Rita; Molnár, Joseph; Ferreira, Maria-José U

2007-01-01

64

Identification of Residues in the Drug Translocation Pathway of the Human Multidrug Resistance P-glycoprotein by Arginine Mutagenesis*  

OpenAIRE

P-glycoprotein (P-gp, ATP-binding cassette B1) is a drug pump that extracts toxic drug substrates from the plasma membrane and catalyzes their ATP-dependent efflux. To map the residues in the drug translocation pathway, we performed arginine-scanning mutagenesis on all transmembrane (TM) segments (total = 237 residues) of a P-gp processing mutant (G251V) defective in folding (15% maturation efficiency) (glycosylation state used to monitor folding). The rationale was that arginines introduced ...

Loo, Tip W.; Bartlett, M. Claire; Clarke, David M.

2009-01-01

65

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

66

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

Energy Technology Data Exchange (ETDEWEB)

{sup 99m}Tc-sestamibi(MIBI) and {sup 99m}Tc-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 {sup 99m}Tc-MIBI and {sup 99m}Tc-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 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 ({rho} < 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.

Cho, Jung Ah; Lee, Jae Tae; Yoo, Jung Ah [School of Medicine, Kyungpook National University, Daegu (Korea, Republic of)] (and others)

2005-02-15

67

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

68

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

69

Detecting parathyroid adenoma using technetium-99m tetrofosmin: comparison with P-glycoprotein and multidrug resistance related protein expression--a preliminary report  

International Nuclear Information System (INIS)

The aim of this study was to investigate the relationships among technetium-99m tetrofosmin (Tc-TF) accumulation in parathyroid adenoma and the expression of P-glycoprotein (Pgp) or multidrug resistance related protein (MRP). Before operation, 33 patients with parathyroid adenomas (larger than 1.5 gm) were studied with parathyroid scintigraphy 10 minutes and 2 hours after intravenous injection of Tc-TF before operation. Immunohistochemical analyses (IHA) were performed on multiple nonconsecutive sections of operative parathyroid specimens to detect Pgp or MRP expression. According to the results of IHA, the 33 parathyroid adenomas were separated into four groups: (1) 2 adenomas with both positive Pgp and positive MRP expression, (2) 1 adenomas with positive Pgp but negative MRP expression, (3) 2 adenomas with negative Pgp but positive MRP expression, and (4) 28 adenomas with both negative Pgp and negative MRP expression. All of 28 adenomas in the group 4 could be detected by Tc-TF parathyroid imaging. All of 5 adenomas in the groups 1 to 3 could not be detected by TcTF parathyroid imaging (p < 0.05). Not only the size of parathyroid adenomas, but also significant Pgp or MRP expression limited the sensitivity of Tc-TF parathyroid imaging to localize parathyroid adenomas before operation

70

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

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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

71

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

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

Nitaya S.N. Ayudhya

2009-01-01

72

P-Glycoprotein-Mediated Efflux and Drug Sequestration in Lysosomes Confer Advantages of K562 Multidrug Resistance Sublines to Survive Prolonged Exposure to Cytotoxic Agents  

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Full Text Available Problem statement: Cellular drug resistance to anticancer agents is major obstacle in cancer chemotherapy and the mechanisms by which these MDR cells possess for protecting themselves to survive prolonged exposure to cytotoxic agents still debating. The study aimed to clarify the role of P-glycoprotein (Pgp and enhanced drug sequestration in lysosomes to confer the multidrug resistance K562 cells with varied degree of Pgp expression. Approach: Erythromyelogenous leukemic K562 and its corresponding Pgp-over expression K562/adr (RF = 26.5 and K562/10000 (RF = 39.6 cells were used. The transport of intrinsic fluorescence molecules including acridine orange and pirarubicin across plasma membrane of living cells was performed by using spectrofluorometric and flow cytometric analysis. Results: Pirarubicin passively diffused through the plasma membrane of K562, K562/adr and K562/10000 cells with the same values of k+ = 3.4±0.3 pL. s-1.cell-1. Similar results were found for acridine orange, which passively diffused through plasma membrane of these cell lines about 30-fold faster than pirarubicin. The mean rate of Pgp-mediated efflux coefficient (ka of pirarubicin was equal to 2.6 ± 0.9 pL.s-1.cell-1 for K562/adr and 4.7 ± 1.0 pL.s-1.cell-1 for K562/10000 cells. The Pgp-mediated efflux of acridine orange could not be determined for K562/adr cells while an enhancement of exocytosis in K562/10000 cells was characterized. The acridine orange exhibited antiproliferative activity and IC50 for K562, K562/adr and K562/10000 cells was 447±40, 715±19 and 1,719±258 nM, respectively. Cytotoxicity of acridine orange was increased by 2-fold in the presence of and 25 nM monensin. Conclusion: The results clearly demonstrated for the first time that by using the same methods and cell lines. The predominant cellular defense mechanism determined in multidrug resistant cells depends upon the nature of molecular probes used. As molecular probe, pirarubicin clearly showed that the Pgp-mediated efflux of drug play as predominant mechanism while AO clearly demonstrated the role of drug sequestration in lysosomes following an enhance exocytosis in both MDR sublines.

Nathupakorn Dechsupa

2009-01-01

73

Interaction of forskolin with the P-glycoprotein multidrug transporter  

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Forskolin and 1,9-dideoxyforskolin, an analogue that does not activate adenylyl cyclase, were tested for their ability to enhance the cytotoxic effects of adriamycin in human ovarian carcinoma cells, SKOV3, which are sensitive to adriamycin and express low levels of P-glycoprotein, and a variant cell line, SKVLB, which overexpresses the P-glycoprotein and has the multidrug reing ance (MDR) phenotype. Forskolin and 1,9-dideoxyforskolin both increased the cytotoxic effects of adriamycin in SKVLB cells, yet had no effect on SKOV3 cells. Two photoactive derivatives of forskolin have been synthesized, 7-O-((2-(3-(4-azido-3-({sup 125}I)iodophenyl)propionamido)ethyl)carbamyl)forskolin, {sup 125}I-6-AIPP-Fsk, and 6-O-((2-(3-(4-azido-3-({sup 125}I)iodophenyl)propionamido)ethyl)carbamyl)forskolin, {sup 125}I-6-AIPP-Fsk, which exhibit specificity for labeling the glucose transporter and aing lyl cyclase, respectively. Both photolabels identified a 140-kDa protein in membranes from SKVLB cells whose labeling was inhibited by forskolin and 1,9-dideoxyforskolin. The data are consistent with forskolin binding to the P-glycoprotein analogous to that of other chemosensitizing drugs that have been shown to partially reverse MDR. The ability of forskolin photolabels to specifically label the transporter, the adenylyl cyclase, and the P-glycoprotein suggests that these proteins may share a common biing g domain for forskolin analogues.

Ming s, D.I.; Seamon, K.B. (Food and Drug Administration, Bethesda, MD (United States)); Speicher, L.A.; Tew, K.D. (Fox Chase Cancer Research Center, Philadelphia, PA (United States)); Ruoho, A.E. (Univ. of Wisconsin, Madison (United States))

1991-08-27

74

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)

75

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

76

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

77

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

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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

78

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

Science.gov (United States)

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

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

2015-01-01

79

Assessment of the in vitro and in vivo properties of a 99mTc-labeled inhibitor of the multidrug resistant gene product P-glycoprotein  

International Nuclear Information System (INIS)

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 99mTc cations (sestamibi, tetrofosmin) as well as [99mTc]Q57, [99mTc]Q58, and [99mTc]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) (99/99mTc1) as a potential inhibitor of Pgp. 99Tc1 enhances the net cell accumulation of Pgp substrates [3H]vinblastine, [3H]vincristine, [3H]colchicine, [99mTc]sestamibi, and [99mTc]tetrofosmin in rat brain endothelial cells (RBE4), an immortalized endothelial cell line that expresses Pgp. In addition, the cell accumulation of 99mTc1 could be increased by verapamil and reserpine, which are known Pgp inhibitors. A multitracer approach was used to study the side effects of 99Tc1 on cell metabolism. The cells were simultaneously incubated with [99mTc]sestamibi, 2-[18F]fluoro-2-deoxyglucose ([18F]FDG), and various 18F]FDG), and various 3H-labeled tracers. Two-dimensional scatter plots of [99mTc]sestamibi uptake/[18F]FDG uptake show typical changes of known Pgp inhibitors including 99Tc1. The effects of 99Tc1 on the in vivo distribution of [99mTc]sestamibi and [18F]FDG in rats also are comparable with the effects of verapamil, an established Pgp inhibitor and calcium channel blocker. We conclude that 99/99mTc1 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

80

Clinical study of 99mTc-MIBI SPECT imaging for detection of multidrug resistant p-glycoprotein expression in lung cancer  

International Nuclear Information System (INIS)

Purpose: Multidrug resistance (MDR) of tumor to cytotoxic drugs is a common cause for failure of chemotherapy in the majority of cancer patients. One of the mechanisms of MDR is due to drug efflux driven by p-glycoprotein (p-GP) expressed on the membrane of tumor cells. the aim of the present study was to develop a method of functional imaging with 99mTc-MIBI to detect the drug efflux mediated by p-GP in lesion of lung cancer. Methods: Before chemotherapy 99mTc-MIBI imaging was performed on each patient with a two-phase protocol (30 and 120 minutes postinjection) in a tomographic mode. Retention indices (RIs) of 99mTc-MIBI at tumor sites were calculated from counts at the lesion sites and the negative value of RI was defined as p-GP positive. According to criteria proposed by the WHO, therapeutic tumor response was scored as no response (NR), partial regression (PR) or complete regression (CR) after 3 courses of chemotherapy. Then, the significance of this technique was assessed. Results: In total, 71 original lesions of lung cancer patients (staged as IIIb?IV) were included in this study. 35 lesions were p-GP(+) and 36 lesions were p-GP(-) by MIBI imaging. 29 (82.9%) lesions in the p-GP (+) group had a therapeutic score of NR, while 24 lesions (66.7%) in p-GP(-) were scored as CR or PR. The accuracy of this method was 74.6%(53/71). Conclusions: Several invasive methods such as immunohistochemical staining and PCR have beeohistochemical staining and PCR have been developed to detect p-GP in tissue. Compared with biopsy, which was subject to sampling errors and heterogeneity of p-GP expression, the present technique was a non-invasive and independent from sampling errors. Therefore, it might serve as an effective complement to the other techniques to detect p-GP mediated MDR

81

The Remarkable Transport Mechanism of P-glycoprotein; a Multidrug Transporter  

OpenAIRE

Human P-glycoprotein (ABCB1) is a primary multidrug transporter located in plasma membranes, that, utilizes the energy of ATP hydrolysis to pump toxic xenobiotics out of cells. P-glycoprotein employs a most unusual molecular mechanism to perform this drug transport function. Here we review our work to elucidate the molecular mechanism of drug transport by P-glycoprotein. High level heterologous expression of human P-glycoprotein, in the yeast Saccharomyces cerevisiae, has facilitated biophysi...

Al-shawi, Marwan K.; Omote, Hiroshi

2005-01-01

82

Photodynamic therapy inhibits p-glycoprotein mediated multidrug resistance via JNK activation in human hepatocellular carcinoma using the photosensitizer pheophorbide a  

OpenAIRE

Abstract Background Multidrug resistance (MDR) is frequently observed after prolonged treatment in human hepatoma with conventional anti-tumor drugs, and photodynamic therapy (PDT) is a recently suggested alternative to overcome MDR. The therapeutic potential of PDT was evaluated in a multidrug resistance (MDR) human hepatoma cell line R-HepG2 with photosensitizer pheophorbide a (Pa). Results Our results demonstrated that intracellular accumulation of Pa was not...

Kong Siu-Kai; Waye Mary; Tsui Stephen; Xuan Ngoc-Ha; Zhang Dong-Mei; Tang Patrick; Fong Wing-Ping; Fung Kwok-Pui

2009-01-01

83

Analysis of Multidrug Transporter in Living Cells. Inhibition of P-glycoprotein-mediated Efflux of Anthracyclines by Ionophores.  

Science.gov (United States)

One of the major obstacles of chemotherapy is that, after repeated treatments, cellular resistance to the drug appears. The problem is that the tumor cells become resistant not only to the drugs which have been used during the treatment but also to other drugs which are structurally and functionally unrelated. This is termed 'multidrug resistance' (MDR). MDR is frequently associated with decreased drug accumulation resulting from enhanced drug efflux. This is correlated with the presence of a membrane protein, P-glycoprotein, which pumps a wide variety of drugs out of cells thus reducing their toxicity. The search for molecules able to reverse MDR is very important. We here report that mobile ionophores such as valinomycin, nonactin, nigericin, monensin, calcimycin, lasalocid inhibit the efflux of anthracycline by P-glycoprotein whereas, channel-forming ionophores such as gramicidin do not. Cyclosporin which is also a strong Ca(2+) chelating agent also inhibits the P-glycoprotein-mediated efflux of anthracycline. PMID:18476229

Borrel, M N; Pereira, E; Fiallo, M; Garnier-Suillerot, A

1994-01-01

84

Using 99mTc-MIBI to evaluate the effects of chemosensitizer on P-glycoprotein in multidrug-resistant carcinoma cells  

International Nuclear Information System (INIS)

Aim: In order to explore the possibility of 99mTc-MIBI to evaluate the impacts of chemosensitizer on P-glycoprotein and thereby to assess the effects of chemosensitizer, the changes of 99mTc-MIBI uptake kinetics and P-glycoprotein levels were observed after using verapamil in MDR human breast cells MCF-7/Ad in the present study. Material and Methods: MDR breast carcinoma cells, MCF-7/Adr were incubated at 37 deg. C. (1) Verapamil (10?mol/L), a chemosensitizer, was added into cell culture medium, while in control group, the same quotient of DMEM. Cells were harvested after 2h incubation with 99mTc-MIBI. (2) Verapamil (10?mol/L) was added into cell culture medium and incubated for 20min, 40min, 60min, 80min, 8h, 24h, 48h, and 72h respectively. Cells were harvested after 2h incubation with 99mTc-MIBI. The radioactivity and P-glycoprotein expression levels were determined. Results: (1) After 2h incubation with verapamil the cellular uptake of 99mTc-MIBI was remarkably higher control group than (t=2.33, P99mTc-MIBI uptake increased with incubation time prolonging (F=58.2 P99mTc-MIBI uptake negatively correlated to the P-glycoprotein expression levels (r= 0.73 P99mTc-MIBI accumulation and P-glycoprotein levels(r=0.16 P>0.05). Conclusion: 99mTc-MIBI may be potentially used to evaluate the effects of chemosensitizer on P-glycoprotein expression levels

85

Using 99mTc-MIBI to evaluate the effects of chemosensitizer on P-glycoprotein in multidrug-resistant carcinoma cells  

International Nuclear Information System (INIS)

Purpose: The changes of 99'mTc-MIBI uptake kinetics and P-glycoprotein levels were observed after using verapamil in MDR human breast cells MCF-7/Adr, in order to establish a method to evaluate the impacts of the chemosensitizer on P-glycoprotein using 99mTc-MIBI and thereby to assess the effects of chemosensitizer. Methods: MDR breast carcinoma cells, MCF-7/Adr were incubated at 370C. (1) Verapamil (10?mol/L), was added into cell culture medium, while in control group, the same quotient of DMEM. Cells were harvested after 2h incubation with 99mTc-MIBI. (2) Verapamil (10?mol/L) was added into cell culture medium and incubated for 20min, 40min, 60min, 80min, 8h, 24h, 48h and 72h respectively. Cells were harvested after 2h incubation with 99mTc-MIBI. The radioactivity and P-glycoprotein expression levels were determined. Results: (1) after 2h incubation with verapamil the cellular uptake of 99mTc-MIBI in verapamil group was remarkably higher than control (t=2.33, P99mTc-MIBI uptake increased with incubation time prolonging (F=58.2,P99mTc-MIBI uptake negatively correlated to the P-glycoprotein expression levels (r=0.73,P99mTc-MIBI accumulation and P-glycoprotein levels(r=0.16,P>0.05). Conclusions: 99mTc-MIBI may be used to evaluate the effects of chemosensitizer on P-glycoprotein expression levels

86

To predict response chemotherapy using technetium-99m tetrofosmin chest images in patients with untreated small cell lung cancer and compare with p-glycoprotein, multidrug resistance related protein-1, and lung resistance-related protein expression  

Energy Technology Data Exchange (ETDEWEB)

Our preliminary studies found technetium-99m tetrofosmin (Tc- TF) chest imaging was related to Pgp or MRP1 expression and successfully predict chemotherapy response and in SCLC in human. However, there was no published literature to study relationship of Tc-TF chest images and LRP expression in SCLC patients. Therefore, the aim of this study was to investigate the relationships among Tc- TF accumulation in untreated small cell lung cancer (SCLC), the expression of P-glycoprotein (Pgp), multidrug resistance related protein-1 (MRP1), and lung resistance-related protein (LRP), as well as the response to chemotherapy in patients with untreated SCLC. Thirty patients with SCLC were studied with chest images 15 to 30 minutes after intravenous injection of Tc-TF before chemotherapeutic induction. Tumor-to-background (T/B) ratios were obtained on the static and plantar Tc-TF chest images. The response to chemotherapy was evaluated upon completion of chemotherapy by clinical and radiological methods. These patients were separated into 15 patients with good response and 15 patients with poor response. No significant differences of prognostic factors (Karnofsky performance status, tumor size, or tumor stage) were found between the patients with good and poor responses. Immunohistochemical analyses were performed on multiple nonconsecutive sections of biopsy specimens to detect Pgp, MRP1, and LRP expression. The difference in T/B ratios on the Tc-TF chest images of the patients with good versus poor response was significant. The differences in T/B ratios of the patients with positive versus negative Pgp expression and with positive versus negative MRP1 expression were significant. The difference in T/B ratios of the patients with positive versus negative LRP expression was not significant. We concluded that Tc-TF chest images could accurately predict chemotherapy response of patients with SCLC. In addition, The Tc-TF tumor uptake was related to Pgp or MRP1 but not LPR expression in SCLC.

Kuo, T.-H.; Liu, F.-Y.; Chuang, C.-Y.; Wu, H.-S.; Wang, J.-J.; Kao, Albert E-mail: albertkaotw@yahoo.com.tw

2003-08-01

87

6,7-Dimethoxy-2-{2-[4-(1H-1,2,3-triazol-1-yl)phenyl]ethyl}-1,2,3,4-tetrahydroisoquinolines as Superior Reversal Agents for P-Glycoprotein-Mediated Multidrug Resistance.  

Science.gov (United States)

P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) is a major obstacle for successful cancer chemotherapy. Based on our previous study, 17 novel compounds with the 6,7-dimethoxy-2-{2-[4-(1H-1,2,3-triazol-1-yl)phenyl]ethyl}-1,2,3,4-tetrahydroisoquinoline scaffold were designed and synthesized. Among them, 2-[(1-{4-[2-(6,7-dimethoxy-3,4-dihydroisoquinolin-2(1H)-yl)ethyl]phenyl}-1H-1,2,3-triazol-4-yl)methoxy]-N-(p-tolyl)benzamide (compound 7?h) was identified as a potent modulator of P-gp-mediated MDR, with high potency (EC50 =127.5±9.1?nM), low cytotoxicity (TI>784.3), and long duration (>24?h) in reversing doxorubicin (DOX) resistance in K562/A02 cells. Compound 7?h also enhanced the effects of other MDR-related cytotoxic agents (paclitaxel, vinblastine, and daunorubicin), increased the accumulation of DOX and blocked P-gp-mediated rhodamine?123 efflux function in K562/A02 MDR cells. Moreover, 7?h did not have any effect on cytochrome (CYP3A4) activity. These results indicate that 7?h is a relatively safe modulator of P-gp-mediated MDR that has good potential for further development. PMID:25470220

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

2014-12-01

88

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

89

To predict response chemotherapy using technetium-99m tetrofosmin chest images in patients with untreated small cell lung cancer and compare with p-glycoprotein, multidrug resistance related protein-1, and lung resistance-related protein expression  

International Nuclear Information System (INIS)

Our preliminary studies found technetium-99m tetrofosmin (Tc- TF) chest imaging was related to Pgp or MRP1 expression and successfully predict chemotherapy response and in SCLC in human. However, there was no published literature to study relationship of Tc-TF chest images and LRP expression in SCLC patients. Therefore, the aim of this study was to investigate the relationships among Tc- TF accumulation in untreated small cell lung cancer (SCLC), the expression of P-glycoprotein (Pgp), multidrug resistance related protein-1 (MRP1), and lung resistance-related protein (LRP), as well as the response to chemotherapy in patients with untreated SCLC. Thirty patients with SCLC were studied with chest images 15 to 30 minutes after intravenous injection of Tc-TF before chemotherapeutic induction. Tumor-to-background (T/B) ratios were obtained on the static and plantar Tc-TF chest images. The response to chemotherapy was evaluated upon completion of chemotherapy by clinical and radiological methods. These patients were separated into 15 patients with good response and 15 patients with poor response. No significant differences of prognostic factors (Karnofsky performance status, tumor size, or tumor stage) were found between the patients with good and poor responses. Immunohistochemical analyses were performed on multiple nonconsecutive sections of biopsy specimens to detect Pgp, MRP1, and LRP expression. The difference in T/B ratios on the Tc-TF chest images of the patients wi the Tc-TF chest images of the patients with good versus poor response was significant. The differences in T/B ratios of the patients with positive versus negative Pgp expression and with positive versus negative MRP1 expression were significant. The difference in T/B ratios of the patients with positive versus negative LRP expression was not significant. We concluded that Tc-TF chest images could accurately predict chemotherapy response of patients with SCLC. In addition, The Tc-TF tumor uptake was related to Pgp or MRP1 but not LPR expression in SCLC

90

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

91

Inhibition of P-Glycoprotein-Mediated Paclitaxel Resistance by Reversibly Linked Quinine Homodimers  

OpenAIRE

P-glycoprotein (P-gp), an ATP-dependent drug efflux pump, has been implicated in multidrug resistance of several cancers as a result of its overexpression. In this work, rationally designed second-generation P-gp inhibitors are disclosed, based on dimerized versions of the substrates quinine and quinidine. These dimeric agents include reversible tethers with a built-in clearance mechanism. The designed agents were potent inhibitors of rhodamine 123 efflux in cultured c...

Pires, Marcos M.; Emmert, Dana; Hrycyna, Christine A.; Chmielewski, Jean

2009-01-01

92

Technetium-99m sestamibi single photon emission computed tomography findings correlated with p-glycoprotein expression, encoded by the multidrug resistance gene-1 messenger ribonucleic acid, in intracranial meningiomas  

International Nuclear Information System (INIS)

The present study evaluated whether technetium-99m sestamibi (99mTc-MIBI) single photon emission computed tomography (SPECT) characteristics of intracranial meningioma are correlated with the histological malignancy, proliferative potential, and P-glycoprotein (Pgp) expression, encoded by the multidrug resistance gene-1 (MDR-1) messenger ribonucleic acid (mRNA). Twenty-one patients with intracranial meningiomas, including 17 benign and four nonbenign meningiomas, underwent 99mTc-MIBI SPECT imaging at 15 minutes (early) and 3 hours (delayed) after injection. The tumor-to-normal pituitary gland ratio was calculated on both early (ER) and delayed (DR) images. Retention index (RI) was calculated using the following formula: (DR-ER)/ER x 100%. Meningioma specimens were examined by immunohistochemistry using anti-Pgp and MIB-1 monoclonal antibody. MDR-1 mRNA expression was also investigated using reverse transcription-polymerase chain reaction assay. 99mTc-MIBI was highly accumulated and retained in the tumors. 99mTc-MIBI SPECT findings were not related to MIB-1 labeling index. 99mTc-MIBI SPECT RI of the Pgp-positive group (-9.12±22.27%) was significantly lower than that of the Pgp-negative group (28.79±22.80%) (p=0.0016). No significant difference was seen in ER and DR between the positive and negative groups. These results show that 99mTc-MIBI may not be useful for determining proliferative potential and determining proliferative potential and histological malignancy, but could predict anticancer drug resistance related to the expression of MDR-1 mRNA and its gene product Pgp in patients with intracranial meningiomas. (author)

93

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

OpenAIRE

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 intrace...

Cara Andrea; Andreotti Mauro; Galluzzo Clementina; Verdoliva Antonio; Costi Roberta; Molinari Agnese; Dupuis Maria; Cianfriglia Maurizio; Di Santo Roberto; Palmisano Lucia

2007-01-01

94

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

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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

95

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

96

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  

Energy Technology Data Exchange (ETDEWEB)

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 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.

Ding, H.J.; Huang, W.T.; Tsai, C.S.; Chang, C.S.; Kao, A. E-mail: albertkaotw@yahoo.com.tw

2003-05-01

97

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

98

Alternative (non-P-glycoprotein) mechanisms of drug resistance in non-Hodgkin's lymphoma.  

Science.gov (United States)

Drug resistance remains a significant obstacle to improving therapeutic outcome following treatment for malignant lymphoma. Eliminating P-glycoprotein as one mechanism of drug resistance may select for alternative, non-P-glycoprotein mechanisms of drug resistance. Understanding these alternative forms of drug resistance is imperative in order to improve therapy for NHL. PMID:9336726

Dalton, W S

1997-10-01

99

Identification of members of the P-glycoprotein multigene family.  

OpenAIRE

Overproduction of P-glycoprotein is intimately associated with multidrug resistance. This protein appears to be encoded by a multigene family. Thus, differential expression of different members of this family may contribute to the complexity of the multidrug resistance phenotype. Three lambda genomic clones isolated from a hamster genomic library represent different members of the hamster P-glycoprotein gene family. Using a highly conserved exon probe, we found that the hamster P-glycoprotein...

Ng, W. F.; Sarangi, F.; Zastawny, R. L.; Veinot-drebot, L.; Ling, V.

1989-01-01

100

P-Glycoprotein and Drug Resistance in Systemic Autoimmune Diseases  

Directory of Open Access Journals (Sweden)

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

Andrea Picchianti-Diamanti

2014-03-01

101

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

102

Interaction of the P-glycoprotein multidrug efflux pump with cholesterol: effects on ATPase activity, drug binding and transport.  

Science.gov (United States)

Resistance to a broad spectrum of structurally diverse chemotherapeutic drugs (multidrug resistance; MDR) is a major impediment to the treatment of cancer. One cause of MDR is the expression at the tumor cell surface of P-glycoprotein (Pgp), which functions as an ATP-powered multidrug efflux pump. Since Pgp interacts with its substrates after they partition into the lipid bilayer, changes in membrane physicochemical properties may have substantial effects on its functional activity. Various interactions between cholesterol and Pgp have been suggested, including a role for the protein in transbilayer movement of cholesterol. We have characterized several aspects of Pgp-cholesterol interactions, and found that some of the previously reported effects of cholesterol result from inhibition of Pgp ATPase activity by the cholesterol-extracting reagent, methyl-beta-cyclodextrin. The presence of cholesterol in the bilayer modulated the basal and drug-stimulated ATPase activity of reconstituted Pgp in a modest fashion. Both the ability of drugs to bind to the protein and the drug transport and phospholipid flippase functions of Pgp were also affected by cholesterol. The effects of cholesterol on drug binding affinity were unrelated to the size of the compound. Increasing cholesterol content greatly altered the partitioning of hydrophobic drug substrates into the membrane, which may account for some of the observed effects of cholesterol on Pgp-mediated drug transport. Pgp does not appear to mediate the flip-flop of a fluorescent cholesterol analogue across the bilayer. Cholesterol likely modulates Pgp function via effects on drug-membrane partitioning and changes in the local lipid environment of the protein. PMID:19049391

Eckford, Paul D W; Sharom, Frances J

2008-12-23

103

Bifendate-chalcone hybrids: A new class of potential dual inhibitors of P-glycoprotein and breast cancer resistance protein.  

Science.gov (United States)

We previously described bifendate-chalcone hybrids as potent P-glycoprotein inhibitors. In the present work, we determine whether these compounds could reverse breast cancer resistance protein (BCRP, ABCG2)-mediated multidrug resistance using HEK293/BCRP cells which was BCRP-transfected stable HEK293 cells. Results indicated that compounds 8d, 8f, 8g and 8h could significantly enhance mitoxantrone accumulation in HEK293/BCRP cells via inhibiting BCRP drug efflux function. The most active compound 8g exhibited little intrinsic cytotoxicity (IC50>100?M), and could reverse BCRP-mediated drug resistance independent of decreasing BCRP expression level. Notably, 8g had little inhibitory effect on multidrug resistance-associated protein 1 (MRP1, ABCC1), another drug efflux transporter. The present findings, together with the previous results, suggest that 8g might be act as dual inhibitors of P-gp and BCRP. PMID:25446092

Gu, Xiaoke; Ren, Zhiguang; Peng, Hui; Peng, Sixun; Zhang, Yihua

2014-12-12

104

Enhanced gene delivery efficiency of cationic liposomes coated with PEGylated hyaluronic acid for anti P-glycoprotein siRNA: A potential candidate for overcoming multi-drug resistance.  

Science.gov (United States)

RNA interference is an effective method to achieve highly specific gene regulation. However, the commonly used cationic liposomes have poor biocompatibility, which may lead to systematic siRNA delivery of no avail. PEGylation is a good strategy in shielding the positive charge of cationic liposomes, but the enhanced serum stability is often in company with compromised cellular uptake and endosome escape. In this study, PEG was covalently linked to negatively charged hyaluronic acid and it was used to coat the liposome-siRNA nanoparticles. The resulting PEG-HA-NP complex had a diameter of 188.6±10.8nm and a dramatically declined zeta-potential from +34.9±4.0mV to -18.2±2.2mV. Owing to the reversed surface charge, PEG-HA-NP could remain stable in fetal bovine serum (FBS) to up to 24h. In contrast with normal PEGylation, hyaluronic acid and PEG co-modified PEG-HA-NP provided comparable cellular uptake and P-glycoprotein downregulation efficacy in MCF-7/ADR cells compared with Lipofectamine RNAiMAX and naked NP regardless of its anionic charged surface. Because of its good biocompatibility in serum, PEG-HA-NP possessed the best tumor accumulation, cellular uptake and subsequently the strongest P-glycoprotein silencing capability in tumor bearing mice compared with naked NP and HA-NP after i.v. injection, with a 34% P-glycoprotein downregulation. Therefore, PEG-HA coated liposomal complex was demonstrated to be a promising siRNA delivery system in adjusting solid tumor P-glycoprotein expression, which may become a potential carrier in reversing MDR for breast cancer therapy. PMID:25448564

Ran, Rui; Liu, Yayuan; Gao, Huile; Kuang, Qifang; Zhang, Qianyu; Tang, Jie; Huang, Kai; Chen, Xiaoxiao; Zhang, Zhirong; He, Qin

2014-12-30

105

Overcoming Multidrug Resistance in Human Cancer Cells by Natural Compounds  

Directory of Open Access Journals (Sweden)

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

106

New structure-activity relationship studies in a series of N,N-bis(cyclohexanol)amine aryl esters as potent reversers of P-glycoprotein-mediated multidrug resistance (MDR).  

Science.gov (United States)

As a continuation of previous research on a new series of potent and efficacious P-gp-dependent multidrug resistant (MDR) reversers with a N,N-bis(cyclohexanol)amine scaffold, we have designed and synthesized several analogs by modulation of the two aromatic moieties linked through ester functions to the N,N-bis(cyclohexanol)amine, aiming to optimize activity and to extend structure-activity relationships (SAR) within the series. This scaffold, when esterified with two different aromatic carboxylic acids, gives origin to four geometric isomers (cis/trans, trans/trans, cis/cis and trans/cis). The new compounds were tested on doxorubicin-resistant erythroleukemia K562 cells (K562/DOX) in the pirarubicin uptake assay. Most of them resulted in being potent modulators of the extrusion pump P-gp, showing potency values ([I](0.5)) in the submicromolar and nanomolar range. Of these, compounds 2b, 2c, 3d, 5a-d and 6d, showed excellent efficacy with a ?(max) close to 1. Selected compounds (2d, 3a, 3b, 5a-d) were further studied to evaluate their doxorubicin cytotoxicity potentiation (RF) on doxorubicin-resistant erythroleukemia K562 cells and were found able to enhance significantly doxorubicin cytotoxicity on K562/DOX cells. The results of both pirarubicin uptake and the cytotoxicity assay, indicate that the new compounds of the series are potent P-gp-mediated MDR reversers. They present a structure with a mix of flexible and rigid moieties, a property that seems critical to allow the molecules to choose the most productive of the several binding modes possible in the transporter recognition site. In particular, compounds 5c and 5d, similar to the already reported analogous isomers 1c and 1d,(29) are potent and efficacious modulators of P-gp-dependent MDR and may be promising leads for the development of MDR-reversal drugs. PMID:23245571

Orlandi, Francesca; Coronnello, Marcella; Bellucci, Cristina; Dei, Silvia; Guandalini, Luca; Manetti, Dina; Martelli, Cecilia; Romanelli, Maria Novella; Scapecchi, Serena; Salerno, Milena; Menif, Hayette; Bello, Ivan; Mini, Enrico; Teodori, Elisabetta

2013-01-15

107

P-glycoprotein-mediated efflux of hydroxyrubicin, a neutral anthracycline derivative, in resistant K562 cells.  

Science.gov (United States)

Hydroxyrubin (OH-Dox), a neutral doxorubicin derivative that is only slightly cross-resistant to doxorubicin (Dox), can be actively pumped out of resistant K562 cells by P-glycoprotein (P-gp). This efflux is saturable and can be inhibited by verapamil. The Michaelis constant is equal to 2 +/- 0.5 microM. However, the efficiency of P-gp in pumping out the drugs is 2.5 times less for OH-Dox than for Dox. This shows that in order to be pumped out by P-gp a molecule does not necessarily have to have a basic center. The mean influx coefficient for the drug is 5 times higher for OH-Dox than for Dox. In conclusion, the degree of resistance of analogs is related not only to their ability to be recognized and transported by P-gp but also, and probably essentially, to their kinetics of uptake. Both parameters have to be taken into account in the rational design of new compounds capable of overcoming multidrug resistance. PMID:7805856

Borrel, M N; Fiallo, M; Priebe, W; Garnier-Suillerot, A

1994-12-19

108

The multidrug resistance (mdr1) gene product functions as an ATP channel.  

OpenAIRE

The multidrug resistance (mdr1) gene product, P-glycoprotein, is responsible for the ATP-dependent extrusion of a variety of compounds, including chemotherapeutic drugs, from cells. The data presented here show that cells with increased levels of the P-glycoprotein release ATP to the medium in proportion to the concentration of the protein in their plasma membrane. Furthermore, measurements of whole-cell and single-channel currents with patch-clamp electrodes indicate that the P-glycoprotein ...

Abraham, E. H.; Prat, A. G.; Gerweck, L.; Seneveratne, T.; Arceci, R. J.; Kramer, R.; Guidotti, G.; Cantiello, H. F.

1993-01-01

109

Simultaneous expression of two P-glycoprotein genes in drug-sensitive Chinese hamster ovary cells.  

OpenAIRE

Overexpression of P-glycoprotein is characteristic of multidrug-resistant cells. We analyzed four P-glycoprotein transcripts that are simultaneously expressed in a drug-sensitive Chinese hamster ovary cell line. We concluded that these transcripts are encoded by two distinct members of a P-glycoprotein multigene family, each of which has two alternative polyadenylation sites. A comparison of the two hamster sequences with the single reported human and mouse P-glycoprotein cDNA sequences demon...

Endicott, J. A.; Juranka, P. F.; Sarangi, F.; Gerlach, J. H.; Deuchars, K. L.; Ling, V.

1987-01-01

110

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

111

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

112

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

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Full Text Available Multidrug resistance to chemotherapy is a major obstacle in the treatment of cancer patients. The best characterised mechanism responsible for multidrug resistance involves the expression of the MDR-1 gene product, P-glycoprotein. However, the resistance process is multifactorial. Studies of multidrug resistance mechanisms have relied on the analysis of cancer cell lines that have been selected and present cross-reactivity to a broad range of anticancer agents. This work characterises a multidrug resistant cell line, originally selected for resistance to the Vinca alkaloid vincristine and derived from the human erythroleukaemia cell K562. This cell line, named Lucena 1, overexpresses P-glycoprotein and have its resistance reversed by the chemosensitisers verapamil, trifluoperazine and cyclosporins A, D and G. Furthermore, we demonstrated that methylene blue was capable of partially reversing the resistance in this cell line. On the contrary, the use of 5-fluorouracil increased the resistance of Lucena 1. In addition to chemotherapics, Lucena 1 cells were resistant to ultraviolet A radiation and hydrogen peroxide and failed to mobilise intracellular calcium when thapsigargin was used. Changes in the cytoskeleton of this cell line were also observed.

RUMJANEK VIVIAN M.

2001-01-01

113

Effect of pentoxifylline on P-glycoprotein mediated vincristine resistance of L1210 mouse leukemic cell line  

International Nuclear Information System (INIS)

Effect of pentoxifylline (PTX) on vincristine (VCR) resistance of multidrug resistant L1210/VCR mouse leukemic cell line was studied. Reversal effect of PTX (in concentration 50-150 mg dm-3) on vincristine resistance, i.e. potentiation of vincristine cytotoxicity on L1210/VCR cells by PTX was found. PTX alone in the above concentration did not exert any significant effect on sensitive or resistant cell lines in the absence of vincristine. Resistance of L1210/VCR cell line was found previously to be accompanied with overexpression of drug transporting P-glycoprotein. Indeed, lower level of 3H-vincristine accumulation by resistant L1210/VCR cell line in comparison with sensitive L1210 cell line was observed. Accumulation of 3H-vincristine by L1210/VCR cell line was significantly increased in the presence of PTX. PTX in the same condition did not exert any considerable effect on accumulation of 3H-vincristine by nonresistant L1210 cells. Observable morphological damage was observed in 1210/VCR cells cultivated in medium containing vincristine (0.2 mg dm-3) and pentoxifylline (100 mg dm-3) in comparison with the non-damaged cells in the presence of vincristine or pentoxifylline alone. The results obtained indicate that pentoxifylline may be considered as a reversal agent in multidrug resistance. (author)

114

Macrocyclic diterpenes resensitizing multidrug resistant phenotypes.  

Science.gov (United States)

Herein, collateral sensitivity effect was exploited as a strategy to select effective compounds to overcome multidrug resistance in cancer. Thus, eleven macrocyclic diterpenes, namely jolkinol D (1), isolated from Euphorbia piscatoria, and its derivatives (2-11) were evaluated for their activity on three different Human cancer entities: gastric (EPG85-257), pancreatic (EPP85-181) and colon (HT-29) each with a variant selected for resistance to mitoxantrone (EPG85-257RN; EPP85-181RN; HT-29RN) and one to daunorubicin (EPG85-257RD; EPP85-181RD; HT-29RD). Jolkinol D (1) and most of its derivatives (2-11) exhibited significant collateral sensitivity effect towards the cell lines EPG85-257RN (associated with P-glycoprotein overexpression) and HT-29RD (altered topoisomerase II expression). The benzoyl derivative, jolkinoate L (8) demonstrated ability to target different cellular contexts with concomitant high antiproliferative activity. These compounds were previously assessed as P-glycoprotein modulators, at non-cytotoxic doses, on MDR1-mouse lymphoma cells. A regression analysis between the antiproliferative activity presented herein and the previously assessed P-glycoprotein modulatory effect showed a strong relation between the compounds that presented both high P-glycoprotein modulation and cytotoxicity. PMID:24864039

Reis, Mariana A; Paterna, Angela; Ferreira, Ricardo J; Lage, Hermann; Ferreira, Maria-José U

2014-07-15

115

Multidrug Resistance in Bacteria  

OpenAIRE

Large amounts of antibiotics used for human therapy, as well as for farm animals and even for fish in aquaculture, resulted in the selection of pathogenic bacteria resistant to multiple drugs. Multidrug resistance in bacteria may be generated by one of two mechanisms. First, these bacteria may accumulate multiple genes, each coding for resistance to a single drug, within a single cell. This accumulation occurs typically on resistance (R) plasmids. Second, multidrug resistance may also occur b...

Nikaido, Hiroshi

2009-01-01

116

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

117

Cytotoxicity of rhein, the active metabolite of sennoside laxatives, is reduced by multidrug resistance-associated protein 1  

OpenAIRE

Anthranoid laxatives, belonging to the anthraquinones as do anthracyclines, possibly increase colorectal cancer risk. Anthracyclines interfere with topoisomerase II, intercalate DNA and are substrates for P-glycoprotein and multidrug resistance-associated protein 1. P-glycoprotein and multidrug resistance-associated protein 1 protect colonic epithelial cells against xenobiotics. The aim of this study was to analyse the interference of anthranoids with these natural defence mechanisms and the ...

Gorkom, B. A. P.; Timmer-bosscha, H.; Jong, S.; Kolk, D. M.; Kleibeuker, J. H.; Vries, E. G. E.

2002-01-01

118

Collateral sensitivity as a strategy against cancer multidrug resistance  

OpenAIRE

While chemotherapy remains the most effective treatment for disseminated tumors, acquired or intrinsic drug resistance accounts for approximately 90% of treatment failure. Multidrug resistance (MDR), the simultaneous resistance to drugs that differ both structurally and mechanistically, often results from drug efflux pumps in the cell membrane that reduce intracellular drug levels to less than therapeutic concentrations. Expression of the MDR transporter P-glycoprotein (P-gp, MDR1, ABCB1) has...

Pluchino, Kristen M.; Hall, Matthew D.; Goldsborough, Andrew S.; Callaghan, Richard; Gottesman, Michael M.

2012-01-01

119

Modulation of HLA class I expression in multidrug-resistant human rhabdomyosarcoma cells  

OpenAIRE

An abnormal HLA expression has been detected in some tumors including rhabdomyosarcoma (RMS). Classical cytotoxic treatment of these tumors, the most common childhood soft tissue malignancy, may induce multidrug resistance (MDR) associated with the expression of a 170-kDa membrane-associated glycoprotein (P-glycoprotein). In order to analyse the connection between modulation of HLA expression and the development of the MDR phenotype mediated by P-glycoprotein in RMS, we used three resistant R...

Melguizo, Consolacion; Prados Salazar, Jose? Carlos; Marchal Corrales, Juan Antonio; Ve?lez, Celia; Carrillo Delgado, Esmeralda Esperanza; Boulaiz, Houria; Sa?nchez Montesinos, I.; Madeddu, Roberto Beniamino; Ara?nega, A.

2003-01-01

120

Analysis of Multidrug Transporter in Living Cells. Inhibition of P-glycoprotein-mediated Efflux of Anthracyclines by Ionophores  

OpenAIRE

One of the major obstacles of chemotherapy is that, after repeated treatments, cellular resistance to the drug appears. The problem is that the tumor cells become resistant not only to the drugs which have been used during the treatment but also to other drugs which are structurally and functionally unrelated. This is termed ‘multidrug resistance’ (MDR). MDR is frequently associated with decreased drug accumulation resulting from enhanced drug efflux. This is correlated with t...

Borrel, Marie-nicole; Pereira, Elene; Fiallo, Marina; Garnier-suillerot, Arlette

1994-01-01

121

P-glycoprotein efflux pump plays an important role in Trypanosoma cruzi drug resistance  

OpenAIRE

Drug resistance in protozoan parasites has been associated with the P-glycoprotein (Pgp), an energy-dependent efflux pump that transports substances across the membrane. Interestingly, the genes TcPGP1 and TcPGP2 have been described in Trypanosoma cruzi, although the function of these genes has not been fully elucidated. The main goal of this work was to investigate Pgp efflux pump activity and expression in T. cruzi lines submitted to in vitro induced resistance to the compounds 4-N-(2-metho...

Campos, Mo?nica Caroline Oliveira; Castro-pinto, Denise Barc?ante; Ribeiro, Grazielle Alves; Berredo-pinho, Ma?rcia Moreira; Gomes, Leonardo Henrique Ferreira; Da Silva Bellieny, Myrtes Santos; Goulart, Carla Marins; Echevarria, A?urea; Leon, Leonor Laura

2013-01-01

122

Effect of Emergence of Fluoroquinolone Resistance on Intrinsic Expression of P-Glycoprotein Phenotype in Corneal Epithelial Cells  

Science.gov (United States)

Abstract Purpose Multidrug resistance (MDR) represents a major obstacle to the success of antimicrobial fluoroquinolone (FQ) therapy. MDR-associated efflux protein pumps antimicrobial agents out of the corneal cells, leading to suboptimal eradication of microbes. This article examines whether long-term FQ (levofloxacin, ofloxacin, and gatifloxacin) therapy can modify the MDR phenotype (P-glycoprotein [P-gp]) on corneal epithelial cells (Statens Seruminstitut Rabbit Cornea [SIRC]). Methods To study the effect of FQ, SIRC cells without any exposure to FQ (control) were compared with the cells exposed to ofloxacin, levofloxacin, and gatifloxacin at a concentration of 10??g/mL for 3 weeks. Efflux activity of P-gp was assessed by in vitro uptake studies (fluorescent and radioactive), flow cytometry, and quantitative real-time polymerase chain reaction (qRT-PCR). Results In the presence of FQ, elevated P-gp expression was noted with uptake, flow cytometry, and qRT-PCR analyses. This study confirms that long-term exposure to antibiotics, particularly FQ, can induce overexpression of P-gp efflux transporter present on the corneal cells. P-gp overexpression is commonly noticed in anticancer drug resistance cell lines; however, for the first time, this report describes overexpression of P-gp due to FQ exposure. Conclusions Based on this result, it is suggested that strategies should be developed and implemented not only to overcome resistance to ocular pathogen but also to FQ-induced cellular resistance. PMID:21830912

Barot, Megha; Gokulgandhi, Mitan R.; Haghnegahdar, Megan; Dalvi, Pranjali

2011-01-01

123

Modulation of multidrug resistance gene expression in human breast cancer cells by (-)-gossypol-enriched cottonseed oil.  

Science.gov (United States)

P-glycoprotein, the product of the multidrug resistance 1 gene, acts as an efflux pump and prevents sufficient intracellular accumulation of several anticancer agents. Thus, it plays a major role in multidrug cancer resistance. Using the non-radioactive cell proliferation MTS assay, none of three ...

124

Molecular Pathways: Regulation and Therapeutic Implications of Multidrug Resistance  

OpenAIRE

Multidrug transporters constitute major mechanisms of multidrug resistance (MDR) in human cancers. The ABCB1 (MDR1) gene encodes a well-characterized transmembrane transporter, termed P-glycoprotein (P-gp), which is expressed in many normal human tissues and cancers. P-gp plays a major role in the distribution and excretion of drugs, and is involved in intrinsic and acquired drug resistance of cancers. The regulation of ABCB1 expression is complex, and has not been well studied in a clinical ...

Chen, Kevin G.; Sikic, Branimir I.

2012-01-01

125

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

126

Detection of P-glycoprotein isoforms by gene-specific monoclonal antibodies.  

OpenAIRE

P-glycoprotein is a highly conserved membrane protein shown to be overexpressed in many multidrug-resistant tumor cell lines. P-glycoprotein is encoded by a small gene family in mammalian cells. Class I and II isoforms cause multidrug resistance, whereas class III does not. In this report, we have characterized three P-glycoprotein-specific monoclonal antibodies (mAbs) by high-resolution epitope mapping with a series of hexapeptides. mAb C494 is gene specific, binding to a sequence present on...

Georges, E.; Bradley, G.; Gariepy, J.; Ling, V.

1990-01-01

127

Multidrug resistant enteric fever.  

Science.gov (United States)

Multidrug resistant typhoid fever (MDRT) is becoming an alarming public health problem in and around Pondicherry, South India. A retrospective review of the multidrug resistant typhoid fever cases admitted to the paediatrics ward of JIPMER Hospital, Pondicherry (India) during 1990 is presented. Prolonged pyrexia, chills and rigors, toxaemia, and tender hepatomegaly often more than 3 cm below the costal margin (often without splenomegaly) were striking features of MDRT cases. The incidence of complications was also greater. Positive blood cultures were observed even after weeks of antibiotic therapy, indicating persistent bacteraemia; resistance was almost always observed for multiple drugs (two or more). The fluoroquinolone group of drugs such as ciprofloxacin have been found to be the best for MDRT in terms of rapid response and cost effectiveness. Cefotaxime has moderate efficacy. PMID:1495126

Chandra, R; Srinivasan, S; Nalini, P; Rao, R S

1992-08-01

128

Cytotoxicity of rhein, the active metabolite of sennoside laxatives, is reduced by multidrug resistance-associated protein 1.  

Science.gov (United States)

Anthranoid laxatives, belonging to the anthraquinones as do anthracyclines, possibly increase colorectal cancer risk. Anthracyclines interfere with topoisomerase II, intercalate DNA and are substrates for P-glycoprotein and multidrug resistance-associated protein 1. P-glycoprotein and multidrug resistance-associated protein 1 protect colonic epithelial cells against xenobiotics. The aim of this study was to analyse the interference of anthranoids with these natural defence mechanisms and the direct cytotoxicity of anthranoids in cancer cell lines expressing these mechanisms in varying combinations. A cytotoxicity profile of rhein, aloe emodin and danthron was established in related cell lines exhibiting different levels of topoisomerases, multidrug resistance-associated protein 1 and P-glycoprotein. Interaction of rhein with multidrug resistance-associated protein 1 was studied by carboxy fluorescein efflux and direct cytotoxicity by apoptosis induction. Rhein was less cytotoxic in the multidrug resistance-associated protein 1 overexpressing GLC4/ADR cell line compared to GLC4. Multidrug resistance-associated protein 1 inhibition with MK571 increased rhein cytotoxicity. Carboxy fluorescein efflux was blocked by rhein. No P-glycoprotein dependent rhein efflux was observed, nor was topoisomerase II responsible for reduced toxicity. Rhein induced apoptosis but did not intercalate DNA. Aloe emodin and danthron were no substrates for MDR mechanisms. Rhein is a substrate for multidrug resistance-associated protein 1 and induces apoptosis. It could therefore render the colonic epithelium sensitive to cytotoxic agents, apart from being toxic in itself. PMID:11986786

van Gorkom, B A P; Timmer-Bosscha, H; de Jong, S; van der Kolk, D M; Kleibeuker, J H; de Vries, E G E

2002-05-01

129

The combined use of paclitaxel-loaded nanoparticles with a low-molecular-weight copolymer inhibitor of P-glycoprotein to overcome drug resistance  

Directory of Open Access Journals (Sweden)

Full Text Available Chung Ping Leon Wan,* Kevin Letchford,* John K Jackson, Helen M Burt Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, Canada*These authors contributed equally to this workAbstract: Two types of nanoparticles were prepared using the diblock copolymer methoxy poly(ethylene glycol-block-poly(caprolactone (MePEG-b-PCL, with either a short PCL block length, which forms micelles, or with a longer PCL block length, which forms kinetically "frozen core" structures termed nanospheres. Paclitaxel (PTX-loaded micelles and nanospheres were evaluated for their cytotoxicity, cellular polymer uptake, and drug accumulation in drug-sensitive (Madin–Darby Canine Kidney [MDCK]II and multidrug-resistant (MDR P-glycoprotein (P-gp-overexpressing (MDCKII-MDR1 cell lines. Both types of PTX-loaded nanoparticles were equally effective at inhibiting proliferation of MDCKII cells, but PTX-loaded micelles were more cytotoxic than nanospheres in MDCKII-MDR1 cells. The intracellular accumulation of both PTX and the diblock copolymers were similar for both nanoparticles, suggesting that the difference in cytotoxicity might be due to the different drug-release profiles. Furthermore, the cytotoxicity of these PTX-loaded nanoparticles was enhanced when these systems were subsequently or concurrently combined with a low-molecular-weight MePEG-b-PCL diblock copolymer, which we have previously demonstrated to be an effective P-gp inhibitor. These results suggest that the dual functionality of MePEG-b-PCL might be useful in delivering drug intracellularly and in modulating P-gp in order to optimize the cytotoxicity of PTX in multidrug-resistant cells.Keywords: multidrug resistance, paclitaxel, nanoparticles, micelles, nanospheres, P-glycoprotein

Wan CP

2013-01-01

130

Reversal of vinblastine transport by chlorpromazine in membrane vesicles from multidrug-resistant human CCRF-CEM leukaemia cells.  

OpenAIRE

The mechanism of action of 2-chlorpromazine (2-chloro-10-(3-dimethylaminopropyl)-phenothiazine) as a reversal agent for P-glycoprotein-mediated multidrug resistance was investigated using inside out-orientated membrane vesicles prepared from vinblastine-resistant human CCRF-CEM leukaemia cells (VBL1000). 2-Chlorpromazine (10 microM) completely inhibited ATP-dependent P-glycoprotein-mediated vinblastine accumulation in the vesicles. Whereas in the absence of added ligands VBL transport was des...

Syed, S. K.; Christopherson, R. I.; Roufogalis, B. D.

1998-01-01

131

Interaction of Transported Drugs with the Lipid Bilayer and P-Glycoprotein through a Solvation Exchange Mechanism  

OpenAIRE

Broad substrate specificity of human P-glycoprotein (ABCB1) is an essential feature of multidrug resistance. Transport substrates of P-glycoprotein are mostly hydrophobic and many of them have net positive charge. These compounds partition into the membrane. Utilizing the energy of ATP hydrolysis, P-glycoprotein is thought to take up substrates from the cytoplasmic leaflet of the plasma membrane and to transport them to the outside of the cell. We examined this model by molecular dynamics sim...

Omote, Hiroshi; Al-shawi, Marwan K.

2006-01-01

132

Development of peptide-based reversing agents for p-glycoprotein-mediated resistance to carfilzomib.  

Science.gov (United States)

Carfilzomib is a novel class of peptidyl epoxyketone proteasome inhibitor and has demonstrated promising activity in multiple clinical trials to treat patients with multiple myeloma and other types of cancers. Here, we investigated molecular mechanisms underlying acquired resistance to carfilzomib and a potential strategy to restore cellular sensitivity to carfilzomib. H23 and DLD-1 cells (human lung and colon adenocarcinoma cell lines) with acquired resistance to carfilzomib displayed marked cross-resistance to YU-101, a closely related proteasome inhibitor, and paclitaxel, a known substrate of Pgp. However, carfilzomib-resistant cells remained sensitive to bortezomib, a clinically used dipeptide with boronic acid pharmacophore. In accordance with these observations, carfilzomib-resistant H23 and DLD-1 cells showed marked upregulation of P-glycoprotein (Pgp) as compared to their parental controls, and coincubation with verapamil, a Pgp inhibitor, led to an almost complete restoration of cellular sensitivity to carfilzomib. These results indicate that Pgp upregulation plays a major role in the development of carfilzomib resistance in these cell lines. In developing a potential strategy to overcome carfilzomib resistance, we as a proof of concept prepared a small library of peptide analogues derived from the peptide backbone of carfilzomib and screened these molecules for their activity to restore carfilzomib sensitivity when cotreated with carfilzomib. We found that compounds as small as dipeptides are sufficient in restoring carfilzomib sensitivity. Taken together, we found that Pgp upregulation plays a major role in the development of resistance to carfilzomib in lung and colon adenocarcinoma cell lines and that small peptide analogues lacking the pharmacophore can be used as agents to reverse acquired carfilzomib resistance. Our findings may provide important information in developing a potential strategy to overcome drug resistance. PMID:22734651

Ao, Lin; Wu, Ying; Kim, Donghern; Jang, Eun Ryoung; Kim, Kyunghwa; Lee, Do-Min; Kim, Kyung Bo; Lee, Wooin

2012-08-01

133

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

134

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

135

Multidrug-resistant tuberculosis  

Directory of Open Access Journals (Sweden)

Full Text Available Introduction: tuberculosis is an increasing problem of global health and the microbialdrug resistance a generating element of worry.Clinical case: 19 year-old patient, who admitted to the emergency room for presentinghemoptysis and who had history of pulmonary tuberculosis with irregular treatment.Multidrug-resistant tuberculosis was documented and different strategies of availablemedical treatment were considered. Due to the increased epidemiological risk and thehistory of poor adherence to the treatment, an in-hospital treatment was carried outwith a satisfactory response.Conclusion: multidrug-resistant tuberculosis is a social risk, keeping the route oftransmission of the disease. Rev.cienc.biomed. 2013;4(1:159-164RESUMEN:Introducción: la tuberculosis (TB pulmonar es un problema creciente de saludmundial y la resistencia a los antibióticos un elemento de preocupación.Caso clínico: paciente de 19 años, quien ingresó al servicio de urgencias por presentarhemoptisis. Antecedente de TB con tratamiento irregular. Se documentó resistenciaa varios medicamentos. Se consideraron las diferentes estrategias de tratamientodisponible. Debido al elevado riesgo epidemiológico y la historia de pobre adherencia altratamiento, se realizó manejo intrahospitalario con respuesta satisfactoria.Conclusiones: la tuberculosis multirresistente (MDR-TB representa un riesgo parala comunidad, teniendo en cuenta la vía de transmisión de la entidad. Rev.cienc.biomed. 2013;4(1:159-164

Álvarez-Gaviria Manuel

2013-06-01

136

The cyclin-dependent kinase inhibitor roscovitine and the nucleoside analog sangivamycin induce apoptosis in caspase-3 deficient breast cancer cells independent of caspase mediated P-glycoprotein cleavage: Implications for therapy of drug resistant breast cancers  

OpenAIRE

Resistance to multiple chemotherapeutic agents is a common clinical problem which can arise during cancer treatment. Drug resistance often involves overexpression of the multidrug resistance MDR1 gene, encoding P-glycoprotein (P-gp), a 170-kDa glycoprotein belonging to the ATP-binding cassette superfamily of membrane transporters. We have recently demonstrated apoptosis-induced, caspase-3-dependent P-gp cleavage in human T-lymphoblastoid CEM-R VBL100 cells. However, P-gp contain many aspartat...

Cappellini, Alessandra; Chiarini, Francesca; Ognibene, Andrea; Mccubrey, James A.; Martelli, Alberto M.

2009-01-01

137

P-glycoprotein expression in primary and metastatic malignant melanoma.  

Science.gov (United States)

Metastatic malignant melanoma is notoriously resistant to chemotherapeutic agents, but the exact mechanisms involved in this drug resistance are unknown. One recently defined major mechanism of multidrug resistance involves the overexpression of P-glycoprotein on cell membranes. In order to evaluate the significance of this putative drug efflux pump for chemoresistance of malignant melanoma, five different antibodies were employed to examine P-glycoprotein expression on tissue from 33 primary malignant melanomas and 35 metastases, before and after chemotherapy, using immunohistological techniques. The expression of P-glycoprotein was low on primary cutaneous melanomas (three of 33), and on metastases (one of 35). Normal tissue in and around the melanoma showed reactivity of endothelial cells, stromal cells and eccrine sweat glands with several antibodies tested. Chemotherapy with drugs commonly used in metastatic melanoma, including agents known to induce P-glycoprotein expression in other tumours (vindesine, cisplatin) had no effect on P-glycoprotein expression in human melanoma metastases. The high chemoresistance of human melanoma cells in vitro and in vivo is probably not mediated via P-glycoprotein, and other possible mechanisms involved will have to be explored in future studies. PMID:7748745

Schadendorf, D; Herfordt, R; Czarnetzki, B M

1995-04-01

138

First evidence of the P-glycoprotein gene expression and multixenobiotic resistance modulation in earthworm.  

Science.gov (United States)

Multixenobiotic resistance (MXR) is an important mechanism of cellular efflux mediated by ATP binding cassette (ABC) transporters that bind and actively remove toxic substrates from the cell. This study was the first to identify ABC transporter P-glycoprotein (P-gp/ABCB1) as a representative of the MXR phenotype in earthworm (Eisenia fetida). The identified partial cDNA sequence of ABCB1 overlapped with ABCB1 homologues of other organisms from 58.5 % to 72.5 %. We also studied the effect of five modulators (verapamil, cyclosporine A, MK571, probenecid, and orthovanadate) on the earthworm's MXR activity by measuring the accumulation of model substrates rhodamine B and rhodamine 123 in whole body tissue of the adult earthworm. MK571, orthovanadate, and verapamil significantly inhibited MXR activity, and rhodamine 123 turned out to better reflect MXR activity in that species than rhodamine B. Our results show that E. fetida can serve well as a test organism for environmental pollutants that inhibit MXR activity. PMID:24622780

Bošnjak, Ivana; Bielen, Ana; Babi?, Sanja; Sver, Lidija; Popovi?, Natalija Topi?; Strunjak-Perovi?, Ivan?ica; Což-Rakovac, Rozelinda; Klobu?ar, Roberta Sauerborn

2014-03-01

139

The application of 99Tcm-MIBI scintimammography to diagnose multidrug resistance of breast cancer  

International Nuclear Information System (INIS)

The author discussed the main mechanism of multidrug resistance of breast cancer tissues, and the correlation between technetium-99m sestamibi (99Tcm-MIBI) breast imaging results, with the expression of drug resistance proteins P-glycoprotein and glutathione-S-transferase-? in human breast cancer. Through not all the results reported before matched each other, as a kind of a noninvasive simple functional test imaging technology in vitro, SPECT can be used to diagnose P-glycoprotein expression in breast cancer, and can be used to predict chemotherapy response

140

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

141

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

142

The Dual Cyclooxygenase/5-Lipoxygenase Inhibitor Licofelone Attenuates P-Glycoprotein-Mediated Drug Resistance in the Injured Spinal Cord  

OpenAIRE

There are currently no proven effective treatments that can improve recovery of function in spinal cord injury (SCI) patients. Many therapeutic compounds have shown promise in pre-clinical studies, but clinical trials have been largely unsuccessful. P-glycoprotein (Pgp, Abcb1b) is a drug efflux transporter of the blood–spinal cord barrier that limits spinal cord penetration of blood-borne xenobiotics. Pathological Pgp upregulation in diseases such as cancer causes heightened resistance to a...

Dulin, Jennifer N.; Moore, Meredith L.; Grill, Raymond J.

2013-01-01

143

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

OpenAIRE

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.

Bankstahl, Jens P.; Bankstahl, Marion; Kuntner, Claudia; Stanek, Johann; Wanek, Thomas; Meier, Martin; Ding, Xiao-qi; Mu?ller, Markus; Langer, Oliver; Lo?scher, Wolfgang

2011-01-01

144

Multidrug-resistant tuberculosis  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english 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; Eliana Dias, Matos.

2013-04-01

145

Evidence of multidrug resistance transporters in rodents olfactory epithelium and their implication in the response to odorants  

OpenAIRE

Multidrug resistance (MDR) is a property of various cells associated with the capacity to reject or efflux a wide range of potentially harmful substances out of the cell. Pumps that effect such efflux are membrane proteins and belong to the ATP- binding cassette (ABC) superfamily. Among the members of the ABC family two are conferring MDR, P-glycoprotein (Pgp) and the multidrug resistance-associated protein (MRP1). In this study we investigated the functional activity of MDR transporters in o...

Molinas, Adrien

2011-01-01

146

Molecular model of the outward facing state of the human P-glycoprotein (ABCB1), and comparison to a model of the human MRP5 (ABCC5)  

OpenAIRE

Abstract Background Multidrug resistance is a particular limitation to cancer chemotherapy, antibiotic treatment and HIV medication. The ABC (ATP binding cassette) transporters human P-glycoprotein (ABCB1) and the human MRP5 (ABCC5) are involved in multidrug resistance. Results In order to elucidate structural and molecular concepts of multidrug resistance, we have constructed a molecular model of the ATP-bound outward facing conformation of the human multidrug ...

Sager Georg; Sylte Ingebrigt; Ravna Aina W

2007-01-01

147

Roles of P-Glycoprotein, Bcrp, and Mrp2 in Biliary Excretion of Spiramycin in Mice?  

OpenAIRE

The multidrug resistance proteins P-glycoprotein (P-gp), breast cancer resistance protein (Bcrp), and multidrug resistance-associated protein 2 (Mrp2) are the three major canalicular transport proteins responsible for the biliary excretion of most drugs and metabolites. Previous in vitro studies demonstrated that P-gp transported macrolide antibiotics, including spiramycin, which is eliminated primarily by biliary excretion. Bcrp was proposed to be the primary pathway for spiramycin secretion...

Tian, Xianbin; Li, Jun; Zamek-gliszczynski, Maciej J.; Bridges, Arlene S.; Zhang, Peijin; Patel, Nita J.; Raub, Thomas J.; Pollack, Gary M.; Brouwer, Kim L. R.

2007-01-01

148

Multidrug-Resistant Tuberculosis (MDR TB)  

Science.gov (United States)

... Home > Lung Disease > Tuberculosis > factsheets Multidrug-Resistant Tuberculosis (MDR TB) Fact Sheet March 2013 Multidrug-resistant tuberculosis (MDR TB) is a form of tuberculosis that is resistant ...

149

Quercetin as a Potential Modulator of P-Glycoprotein Expression and Function in Cells of Human Pancreatic Carcinoma Line Resistant to Daunorubicin  

Directory of Open Access Journals (Sweden)

Full Text Available P-glycoprotein (P-gp is one of the ABC transporters responsible for the resistance of several tumours to successful chemotherapy. Numerous agents are capable of interfering with the P-gp-mediated export of drugs but unfortunately most of them produce serious side effects. Some plant polyphenols, including the flavonol quercetin (Q, manifest anti-neoplastic activity mainly due to their influence on cell cycle control and apoptosis. Reports are also available which show that Q may intensify action of cytostatic drugs and suppress the multidrug resistance (MDR phenomenon. The study aimed at determination if Q sensitizes cells resistant to daunorubicin (DB through its effect on P-gp expression and action. The experiments were conducted on two cell lines of human pancreatic carcinoma, resistant to DB EPP85-181RDB and sensitive EPP85-181P as a comparison. Cells of both lines were exposed to selected concentrations of Q and DB, and then membranous expression of P-gp and its transport function were examined. The influence on expression of gene for P-gp (ABCB1 was also investigated. Results of the studies confirmed that Q affects expression and function of P-gp in a concentration-dependent manner. Moreover it decreased expression of ABCB1. Thus, Q may be considered as a potential modulator of P-gp.

Piotr Dziegiel

2010-02-01

150

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

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Full Text Available 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<0.05, and the expression of the multidrug resistance gene and P-glycoprotein were significantly suppressed (p<0.05. The combination of curcumin and vincristine significantly inhibited xenograft growth. The expression of the multidrug resistance protein 1 and survivin genes was significantly reduced in xenografts of curcumin-treated mice and mice treated with both curcumin and vincristine relative to control mice. CONCLUSION: Curcumin has strong reversal effects on the multidrug resistance of human colon carcinoma in vitro and in vivo.

Wei-Dong Lu

2013-05-01

151

Targeted chemotherapy in drug-resistant tumors, noninvasive imaging of P-glycoprotein-mediated functional transport in cancer, and emerging role of Pgp in neurodegenerative diseases.  

Science.gov (United States)

Multidrug resistance (MDR) mediated by overexpression of P-glycoprotein (Pgp) is one of the best characterized transporter-mediated barriers to successful chemotherapy in cancer patients and is also a rapidly emerging target in the progression of neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Therefore, strategies capable of delivering chemotherapeutic agents into drug-resistant tumors and targeted radiopharmaceuticals acting as ultrasensitive molecular imaging probes for detecting functional Pgp expression in vivo could be expected to play a vital role in systemic biology as personalized medicine gains momentum in the twenty-first century. While targeted therapy could be expected to deliver optimal doses of chemotherapeutic drugs into the desired targets, the interrogation of Pgp-mediated transport activity in vivo via noninvasive imaging techniques (SPECT and PET) would be beneficial in stratification of patient populations likely to benefit from a given therapeutic treatment, thereby assisting management of drug resistance in cancer and treatment of neurodegenerative diseases. Both strategies could play a vital role in advancement of personalized treatments in cancer and neurodegenerative diseases. Via this tutorial, authors make an attempt in outlining these strategies and discuss their strengths and weaknesses. PMID:19949924

Sivapackiam, Jothilingam; Gammon, Seth T; Harpstrite, Scott E; Sharma, Vijay

2010-01-01

152

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

153

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

OpenAIRE

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...

Lin Ge; Kw, To Kenneth; Chai Stella

2010-01-01

154

Synthesis, activity and pharmacophore development for isatin-?-thiosemicarbazones with selective activity towards multidrug resistant cellsa  

OpenAIRE

We have recently identified a new class of compounds that selectively kill cells that express P-glycoprotein (P-gp, MDR1), the ATPase efflux pump that confers multidrug resistance on cancer cells. Several isatin-?-thiosemicarbazones from our initial study have been validated, and a range of analogs synthesized and tested. A number demonstrated improved MDR1-selective activity over the lead, NSC73306 (1). Pharmacophores for cytotoxicity and MDR1-selectivity were generated to delineate the str...

Hall, Matthew D.; Salam, Noeris K.; Hellawell, Jennifer L.; Fales, Henry M.; Kensler, Caroline B.; Ludwig, Joseph A.; Szakacs, Gergely; Hibbs, David E.; Gottesman, Michael M.

2009-01-01

155

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

156

The role of half-transporters in multidrug resistance  

DEFF Research Database (Denmark)

ATP-binding cassette proteins comprise a superfamily of transporter proteins, a subset of which have been implicated in multidrug resistance. Although P-glycoprotein was described over 15 years ago, the recent expansion in the number of transporters identified has prompted renewed interest in the role of drug transporters in clinical drug resistance. These newly identified transporters include additional members of the MRP family, ABC2, and a new half-transporter, MXR/BCRP/ABCP1. This half-transporter confers high levels of resistance to mitoxantrone, anthracyclines, and the camptothecins SN-38 and topotecan. At 72 kDa, MXR localizes to the plasma membrane in cells which highly overexpress the protein either through gene amplification or though gene rearrangement. Future studies will be aimed at identifying an inhibitor, and attempting to translate recognition of this new transporter into a target for anticancer treatment.

Bates, S E; Robey, R

2001-01-01

157

Multidrug Resistance in Prostate Cancer  

OpenAIRE

Advanced hormone refractory prostate cancer constitutes a therapeutic challenge, because all available treatment strategies have failed to substantially increase cancer specific survival. Among these strategies, a multitude of chemotherapeutic approaches did not offer a superior life expectancy longer than a few months. Failure of chemotherapy may be caused by multidrug resistance (MDR) mechanisms protecting cancer cells against cytotoxic drugs. The question arises whether the...

Brussel, J. P.

2005-01-01

158

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

159

Pharmacotherapy for multidrug resistant tuberculosis  

OpenAIRE

The current global concern in the treatment of tuberculosis (TB) is the emergence of resistance to the two most potent drugs namely, isoniazid and rifampicin. Emergence of multidrug resistance tuberculosis (MDR-TB) is now a health problem faced by most of the developing countries as well as developed countries across the globe. MDR-TB is a man-made disease that is caused by improper treatment, inadequate drug supplies, and poor patient supervision. HIV infection and AIDS have been implicated ...

Chhabra, Naveen; Aseri, M. L.; Dixit, Ramakant; Gaur, S.

2012-01-01

160

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

161

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

162

Direct interaction between verapamil and doxorubicin causes the lack of reversal effect of verapamil on P-glycoprotein mediated resistance to doxorubicin in vitro using L1210/VCR cells  

International Nuclear Information System (INIS)

Mouse leukemic cell sub-line L 1210/VCR exerts expressive multidrug resistance (MDR) that is mediated by P-glycoprotein. Cells originally adapted to vincristine are also extremely resistant to doxorubicin. Resistance to both vincristine and doxorubicin is connected with depression of drug uptake. While resistance of L 121 O cells to vincristine could be reversed by verapamil as chemo-sensitizer, resistance of cells to doxorubicin was insensitive to verapamil. Action of verapamil (well-known inhibitor of PGP activity) on multidrug resistance was often used as evidence that MDR is mediated by PGP. From this point it may be possible that the resistance of L1210/VCR cells to vincristine is mediated by PGP and the resistance to doxorubicin is mediated by other PGP-independent system. Another and more probable explanation of different effect of verapamil on resistance of L1210/VCR cells to vincristine and doxorubicin may be deduced from the following fact: Using UV spectroscopy we found that doxorubicin dissolved in water buffered medium interacts effectively with verapamil. This interaction may be responsible for the decrease of concentration of both drugs in free effective form and consequently for higher survival of cells. In contrast to doxorubicin vincristine does not give any interaction with verapamil that is measurable by UV spectroscopy and resistance of L1210/VCR cells to vincristine may be fully reversed by verapamil. (authors)thors)

163

Overcoming multidrug resistance by RNA interference.  

Science.gov (United States)

The ATP-binding cassette (ABC)-transporter P-glycoprotein (Pgp, also known as ABCB1) is the best characterized factor involved in multidrug resistance (MDR) of cancer cells. Pgp, which is encoded by the MDR1 gene, acts as a membrane-embedded drug extrusion pump for multiple structurally unrelated cytotoxic drugs. Inhibition of the pump activity of Pgp by low-molecular weight pharmacologically active compounds as a method to reverse MDR in cancer patients has been studied extensively, but so far clinical trials have generally been disappointing. Thus, experimental strategies for overcoming MDR are under investigation. These approaches include the application of the RNA interference (RNAi) technology. RNAi is a physiological mechanism triggered by small double-stranded RNA molecules resulting in a sequence-specific gene-silencing. Besides its potential for development of novel therapeutics, RNAi also offers the possibility for specific inhibition of cellular targets in functional investigations. For specific inhibition of Pgp by triggering the RNAi pathway, transient gene-silencing by application of small interfering RNA (siRNA), and stable inhibition by transfection of MDR cancer cells with short hairpin RNA (shRNA) encoding expression cassettes encoded on plasmid DNA are described. Efficacy of RNAi on MDR1 mRNA expression level is determined by quantitative real-time RT-PCR and Northern blot. The consequences of RNAi on protein expression level are measured by Western blot and immunohistochemistry. The effects on the drug extrusion activity are measured by a drug accumulation assay based on flow cytometry, and reversal of the drug-resistant phenotype by assessment of drug-specific IC(50)-values by a cell proliferation assay based on colorimetry. PMID:19949936

Stege, Alexandra; Krühn, Andrea; Lage, Hermann

2010-01-01

164

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

DEFF Research Database (Denmark)

Mechanisms of drug resistance other than P-glycoprotein are of increasing interest as the list of newly identified members of the ABC transport family has grown. We sought to characterize the phenotype of the newly discovered ABC transporter encoded by the mitoxantrone resistance gene, MXR, also known as ABCP1 or BCRP. The pharmacodynamics of mitoxantrone and 12 other fluorescent drugs were evaluated by confocal microscopy in four multidrug-resistant human colon (S1) and breast (MCF-7) cancer cell lines. We utilized two sublines, MCF-7 AdVp3000 and S1-M1-80, and detected overexpression of MXR by PCR, immunoblot assay and immunohistochemistry. These MXR overexpressing sublines were compared to cell lines with P-glycoprotein- and MRP-mediated resistance. High levels of cross-resistance were observed for mitoxantrone, the anthracyclines, bisantrene and topotecan. Reduced levels of mitoxantrone, daunorubicin, bisantrene, topotecan, rhodamine 123 and prazosin were observed in the two sublines with high MXR expression. Neither the P-glycoprotein substrates vinblastine, paclitaxel, verapamil and calcein-AM, nor the MRP substrate calcein, were extruded from MCF-7 AdVp3000 and S1-M1-80 cells. Thus, the multidrug-resistant phenotype due to MXR expression is overlapping with, but distinct from, that due to P-glycoprotein. Further, cells that overexpress the MXR protein seem to be more resistant to mitoxantrone and topotecan than cells with P-glycoprotein-mediated multidrug resistance. Our studies suggest that the ABC half-transporter, MXR, is a potent, new mechanism for conferring multiple drug resistance. Definition of its mechanism of transport and its role in clinical oncology is required.

Litman, Thomas; Brangi, M

2000-01-01

165

Limited oral bioavailability and active epithelial excretion of paclitaxel (Taxol) caused by P-glycoprotein in the?intestine  

OpenAIRE

In mice, the mdr1a and mdr1b genes encode drug-transporting proteins that can cause multidrug resistance in tumor cells by lowering intracellular drug levels. These P-glycoproteins are also found in various normal tissues such as the intestine. Because mdr1b P-glycoprotein is not detectable in the intestine, mice with a homozygously disrupted mdr1a gene [mdr1a(?/?) mice] do not contain functional P-glycoprotein in this organ. We have used these mdr1a(?/?) mice to study the effect of g...

Sparreboom, A.; Asperen, J.; Mayer, U.; Schinkel, A. H.; Smit, J. W.; Meijer, D. K. F.; Borst, P.; Nooijen, W. J.; Beijnen, J. H.; Tellingen, O.

1997-01-01

166

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

OpenAIRE

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...

Molento Marcelo B.; Prichard Roger K.

2001-01-01

167

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

168

Apatinib (YN968D1) reverses multidrug resistance by inhibiting the efflux function of multiple ATP-binding cassette transporters  

OpenAIRE

Apatinib, a small-molecule multi-targeted tyrosine kinase inhibitor, is in phase III clinical trial for treatment of patients with non-small cell lung cancer and gastric cancer in China. In this study, we determined the effect of apatinib on the interaction of specific antineoplastic compounds with P-glycoprotein (P-gp, ABCB1), multidrug resistance protein 1 (MRP1, ABCC1) and breast cancer resistance protein (BCRP, ABCG2). Our results showed that apatinib significantly enhanced the cytotoxici...

Mi, Yan-jun; Liang, Yong-ju; Huang, Hong-bing; Zhao, Hong-yun; Wu, Chung-pu; Wang, Fang; Tao, Li-yang; Zhang, Chuan-zhao; Dai, Chun-ling; Tiwari, Amit K.; Ma, Xiao-xu; Wah To, Kenneth Kin; Ambudkar, Suresh V.; Chen, Zhe-sheng; Fu, Li-wu

2010-01-01

169

Mobile ionophores are a novel class of P-glycoprotein inhibitors. The effects of ionophores on 4'-O-tetrahydropyranyl-adriamycin incorporation in K562 drug-resistant cells.  

Science.gov (United States)

The decrease of the intracellular concentration of drug in resistant cells compared to sensitive cells is, in most cases, correlated with the presence, in the membrane of resistant cells, of a 170-kDa P-glycoprotein responsible for an active efflux of the drug. In an attempt to identify mechanism(s) by which multidrug resistance can be circumvented, we have examined the cellular accumulation of 4'-O-tetrahydropyranyl-adriamycin, alone and in conjunction with various ionophores on the one hand and with cyclosporin A on the other hand. The present study was performed using a spectrofluorometric method with which it is possible to follow continuously the uptake and release of fluorescent molecules by living cells, as the incubation of the cells with the drug proceeds. Erythroleukemia K562 cell lines were used. Using experimental conditions in which these ionophores were unable to modify either the intracellular pH, or the transmembrane potential, or to induce an intracellular ATP depletion, we have shown that mobile ionophores as well as cyclosporin inhibit the P-glycoprotein-mediated efflux of 4'-O-tetrahydropyranyl-adriamycin in K562 resistant cells, whereas gramicidin, a channel-forming ionophore, does not. The concentration that must be used to inhibit 50% of the efflux was 0.7 microM for valinomycin, 0.4 microM for nonactin, 0.2 microM for nigericin, 1.1 microM for monensin, 0.4 microM for lasalocid, 1.2 microM for calcimycin and 0.4 microM for cyclosporin. Due to the high toxicity of the ionophores, the observation that they increased 4'-O-tetrahydropyranyl-adriamycin accumulation in the multidrug-resistant cells is not correlated with an effect of these compounds on drug resistance. However, the correlation exists in the case of cyclosporin. From our data showing that lipophilic neutral complexes, formed between carboxylic ionophores and metal ions, are both able to inhibit the P-glycoprotein-mediated efflux of anthracycline we can infer that the lipophilicity but not the cationic charge is an important physical property. PMID:7518390

Borrel, M N; Pereira, E; Fiallo, M; Garnier-Suillerot, A

1994-07-01

170

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

171

Changes in P-glycoprotein activity are mediated by the growth of a tumour cell line as multicellular spheroids  

OpenAIRE

Abstract Background Expression of P-glycoprotein (P-gp), the multidrug resistance (MDR) 1 gene product, can lead to multidrug resistance in tumours. However, the physiological role of P-gp in tumours growing as multicellular spheroids is not well understood. Recent evidence suggests that P-gp activity may be modulated by cellular components such as membrane proteins, membrane-anchoring proteins or membrane-lipid composition. Since, multicellular spheroids studies have evidenc...

Raúl Barrera-Rodríguez; Valeria Ponce

2005-01-01

172

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

173

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

174

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-04-15

175

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

International Nuclear Information System (INIS)

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

176

Cremophor EL reversed multidrug resistance in vitro but not in tumor-bearing mouse models.  

Science.gov (United States)

Cremophor EL (CreEL), a polyethylene castor oil used as a vehicle for cyclosporin A and taxol, reverses P-glycoprotein-mediated drug resistance. The vehicle in an i.v. dosage form of PSC 833, [3'-keto-Bmt1]-[Val2]-cyclosporin, contains CreEL and has been presumed to have the potentiation of the reversal activity of PSC 833. To examine this possibility, we compared reversal activities of CreEL and PSC 833 against multidrug resistance (MDR) in vitro and in vivo. Both CreEL and PSC 833 inhibited P-glycoprotein-mediated efflux of [3H]vincristine from adriamycin-resistant myelogenous leukemia K562. The sensitization of multidrug-resistant cell lines to anticancer drugs by CreEL and PSC 833 was selective to MDR-related agents, suggesting a specific interference of the P-glycoprotein function by the two MDR modulators. The concentration-dependent activity of the modulators demonstrated that CreEL is at least 100 times less potent than PSC 833. The in vivo reversal effects of CreEL alone and PSC 833 in the vehicle were investigated in multidrug-resistant tumor-bearing mouse models. In vincristine-resistant P388 leukemia-bearing mice, neither i.v. nor i.p. administration of CreEL even at 1440 mg/kg enhanced the antitumor activity of adriamycin. The in vivo negligible activity of CreEL was confirmed in an HCT-15-bearing athymic mouse model. In contrast, PSC 833 significantly enhanced the antitumor activity of adriamycin in the in vivo models. The reversal activity of CreEL restricted to in vitro leads us to conclude that the vehicle containing CreEL did not potentiate the activity of PSC 833 in the tumor-bearing mouse models. PMID:8991185

Watanabe, T; Nakayama, Y; Naito, M; Oh-hara, T; Itoh, Y; Tsuruo, T

1996-11-01

177

Development of peptide-based reversing agents for P-glycoprotein-mediated resistance to carfilzomib  

OpenAIRE

Carfilzomib is a novel class of peptidyl epoxyketone proteasome inhibitor and has demonstrated promising activity in multiple clinical trials to treat patients with multiple myeloma and other types of cancers. Here, we investigated molecular mechanisms underlying acquired resistance to carfilzomib and a potential strategy to restore cellular sensitivity to carfilzomib. H23 and DLD-1 cells (human lung and colon adenocarcinomas cell lines) with acquired resistance to carfilzomib displayed marke...

Ao, Lin; Wu, Ying; Kim, Donghern; Jang, Eun Ryoung; Kim, Kyunghwa; Lee, Do-min; Kim, Kyung Bo; Lee, Wooin

2012-01-01

178

99Tcm-tetrofosmin: a functional imaging agent of evaluation P-glycoprotein modulation in vivo  

International Nuclear Information System (INIS)

99Tcm-tetrof0smin is a widely available and conveniently prepared tracer that has been shown to be a transport substrate for P-glycoprotein and multidrug resistance protein in vitro and in vivo. Its properties are similar but not identical to those of 99Tcm-sestamibi. The available data suggest that clinical studies involving imaging of multidrug resisttance function and in vivo modulation of multidrug resisttanee function could be performed with 99Tcm-tetrofosmin or 99Tcm-sestamibi, but the two should probably not be used interchangeably. (authors)

179

Downregulation of mdr-1 expression by 8-Cl-cAMP in multidrug resistant MCF-7 human breast cancer cells.  

OpenAIRE

8-Cl-cAMP, a site-selective analogue of cAMP, decreased mdr-1 expression in multidrug-resistant human breast cancer cells. A sixfold reduction of mdr-1 mRNA expression by 8-Cl-cAMP began within 8 h of treatment and was associated with a decrease in the synthesis of P-glycoprotein and with an increase in vinblastine accumulation. A reduction in mdr-1 expression after 8-Cl-cAMP treatment was also observed in multidrug-resistant human ovarian cancer cell lines. 8-Cl-cAMP is known to change the r...

Scala, S.; Budillon, A.; Zhan, Z.; Cho-chung, Y. S.; Jefferson, J.; Tsokos, M.; Bates, S. E.

1995-01-01

180

ATP-dependent transport of vinblastine in vesicles from human multidrug-resistant cells  

Energy Technology Data Exchange (ETDEWEB)

Resistance of human cancer cells to multiple cytotoxic hydrophobic agents (multidrug resistance) is due to overexpression of the MDR1 gene, whose product is the plasma membrane P-glycoprotein. Plasma membrane vesicles partially purified from multidrug-resistant human KB carcinoma cells, but not from drug-sensitive cells, accumulate ({sup 3}H)vinblastine in an ATP-dependent manner. This transport is osmotically sensitive, with an apparent K{sub m} of 38 {mu}M for ATP and of {approx} 2 {mu}M for vinblastine. The nonhydrolyzable analog adenosine 5{prime}-({beta},{gamma}-imido)triphosphate does not substitute for ATP but is a competitive inhibitor of ATP for the transport process. Vanadate, and ATPase inhibitor, is a potent noncompetitive inhibitor of transport. These results indicate that hydrolysis of ATP is probably required for active transport vinblastine. Several other drugs to which multidrug-resistant cell lines are resistant inhibit transport, with relative potencies as follows: vincristine > actinomycin D > daunomycin > colchicine = puromycin. Verapamil and quinidine, which reverse the multidrug-resistance phenotype, are good inhibitors of the transport process. These results confirm that multidrug-resistant cells express an energy-dependent plasma membrane transporter for hydrophobic drugs, and establish a system for the detailed biochemical analysis of this transport process.

Horio, M.; Gottesman, M.M.; Pastan, I. (National Institutes of Health, Bethesda, MD (USA))

1988-05-01

181

ATP-dependent transport of vinblastine in vesicles from human multidrug-resistant cells  

International Nuclear Information System (INIS)

Resistance of human cancer cells to multiple cytotoxic hydrophobic agents (multidrug resistance) is due to overexpression of the MDR1 gene, whose product is the plasma membrane P-glycoprotein. Plasma membrane vesicles partially purified from multidrug-resistant human KB carcinoma cells, but not from drug-sensitive cells, accumulate [3H]vinblastine in an ATP-dependent manner. This transport is osmotically sensitive, with an apparent Km of 38 ?M for ATP and of ? 2 ?M for vinblastine. The nonhydrolyzable analog adenosine 5'-[?,?-imido]triphosphate does not substitute for ATP but is a competitive inhibitor of ATP for the transport process. Vanadate, and ATPase inhibitor, is a potent noncompetitive inhibitor of transport. These results indicate that hydrolysis of ATP is probably required for active transport vinblastine. Several other drugs to which multidrug-resistant cell lines are resistant inhibit transport, with relative potencies as follows: vincristine > actinomycin D > daunomycin > colchicine = puromycin. Verapamil and quinidine, which reverse the multidrug-resistance phenotype, are good inhibitors of the transport process. These results confirm that multidrug-resistant cells express an energy-dependent plasma membrane transporter for hydrophobic drugs, and establish a system for the detailed biochemical analysis of this transport process

182

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

183

Effects of dietary ingredients on function and expression of P-glycoprotein in human intestinal epithelial cells.  

Science.gov (United States)

The present study was conducted to investigate the functional and transcriptional modulation of P-glycoprotein (MDR-1) by several dietary ingredients (piperine, capsaicin, daidzein, genistein, sesamin, curcumin, taurine) in vinblastine-resistant colon carcinoma LS-180 cells (LS-180V cells). The amount of rhodamine 123 accumulated in LS-180V cells was significantly increased by capsaicin, piperine and sesamin, whereas it was significantly reduced by daidzein and genistein which stimulated the efflux of rhodamine 123. These results suggest that the P-glycoprotein-mediated efflux is inhibited by piperine, capsaicin and sesamin and stimulated by daidzein and genistein. The concurrent addition of piperine and capsaicin seemed to inhibit synergistically the P-glycoprotein-mediated efflux. Pretreatment with sesamin for 48 h caused a significant increase in MDR1 mRNA expression without a significant effect on the expression of P-glycoprotein or accumulation of rhodamine 123. Similar pretreatment with other ingredients had little effect on the expression of MDR1 mRNA or P-glycoprotein, suggesting that they do not cause transcriptional modulation of P-glycoprotein. Piperine, genistein and curcumin have been suggested to stimulate P-glycoprotein-mediated efflux without increasing P-glycoprotein expression. In LS-180V cells, significant increases in mRNA levels of multi-drug resistance associated protein 1 (MRP1) or MRP3 were observed on pretreatment with capsaicin, daidzein, piperine and sesamin. In conclusion, our results suggest that P-glycoprotein-mediated efflux is significantly affected by dietary ingredients. Also, capsaicin, daidzein, piperine and sesamin increased significantly the mRNA expression of MRP1 or MRP3. Thus, the present study provides further evidence that repeated exposure to dietary ingredients can cause drug-food interactions by affecting the function and mRNA expression of intestinal transporters such as P-glycoprotein. PMID:20118549

Okura, Takashi; Ibe, Michiko; Umegaki, Keizo; Shinozuka, Kazumasa; Yamada, Shizuo

2010-01-01

184

Poloxamer 407/TPGS mixed micelles for delivery of gambogic acid to breast and multidrug-resistant cancer  

OpenAIRE

Vipin Saxena, M Delwar HussainDepartment of Pharmaceutical Sciences, Irma Lerma Rangel College of Pharmacy, Texas A&M Health Science Center, Kingsville, TX, USABackground: Delivery of a high concentration of anticancer drugs specifically to cancer cells remains the biggest challenge for the treatment of multidrug-resistant cancer. Poloxamers and D-?-Tocopheryl polyethylene glycol 1000 succinate (TPGS) are known inhibitors of P-glycoprotein (P-gp). Mixed micelles prepared fro...

Md, Hussain; Saxena V

2012-01-01

185

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

Directory of Open Access Journals (Sweden)

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

186

Identification of multi-drug resistance gene (MDR1 in equine ileum  

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Full Text Available 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 bioavailability 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.

Natalini Cláudio Corrêa

2006-01-01

187

Imaging of multidrug resistance in cancer  

OpenAIRE

Primary intrinsic and/or acquired multidrug resistance (MDR) is the main obstacle to successful cancer treatment. Functional molecular imaging of MDR in cancer using single photon or positron emitters may be helpful to identify multidrug-resistant tumours and predict not only those patients who are resistant to treatment, with a clinically unfavourable prognosis, but also those who are susceptible to the development of drug toxicity or even certain tumours . Variations in the mdr1 gene produc...

Dizdarevic, S.; Peters, A. M.

2011-01-01

188

Quercetin as a Potential Modulator of P-Glycoprotein Expression and Function in Cells of Human Pancreatic Carcinoma Line Resistant to Daunorubicin  

OpenAIRE

P-glycoprotein (P-gp) is one of the ABC transporters responsible for the resistance of several tumours to successful chemotherapy. Numerous agents are capable of interfering with the P-gp-mediated export of drugs but unfortunately most of them produce serious side effects. Some plant polyphenols, including the flavonol quercetin (Q), manifest anti-neoplastic activity mainly due to their influence on cell cycle control and apoptosis. Reports are also available which show that Q may intensify a...

Piotr Dziegiel; Magdalena Chmielewska; Maciej Zabel; Sylwia Borska; Miroslaw Sopel

2010-01-01

189

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

OpenAIRE

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...

Russell Nigel H; Seedhouse Claire; Grundy Martin; Pallis Monica

2011-01-01

190

Susceptibility of juvenile and adult blood–brain barrier to endothelin-1: regulation of P-glycoprotein and breast cancer resistance protein expression and transport activity  

OpenAIRE

Abstract Background P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) play a critical role in keeping neurotoxic substances from entering the brain. We and others have previously reported an impact of inflammation on the regulation of adult blood–brain barrier (BBB) efflux transporters. However, studies in children have not been done. From the pediatric clinical perspective, it is important to understand how the central nervous system (CNS) and BBB drug effl...

Harati Rania; Villégier Anne-Sophie; Banks William A; Mabondzo Aloise

2012-01-01

191

Identification of the cyclosporin-binding site in P-glycoprotein.  

Science.gov (United States)

The binding site of cyclosporin A to P-glycoprotein was characterized by using a multidrug-resistant Chinese hamster ovary cell line. P-glycoprotein photolabeled with diazirine-cyclosporin A analogue was purified by a two-step process involving continuous elution electrophoresis followed by wheat germ agglutinin-agarose precipitation. The cyclosporin A covalently bound to P-glycoprotein and to subsequent proteolytic fragments was detected by Western blot analysis using a monoclonal antibody against cyclosporin A. Proteolytic digestion of purified P-glycoprotein by V8 generated a major fragment of 15 kDa photolabeled by cyclosporin A, while proteolysis of P-glycoprotein photolabeled by [125I]-iodoaryl azidoprazosin generated a major fragment of 7 kDa. Limited proteolysis of cyclosporin A-photolabeled P-glycoprotein with trypsin indicated that the major binding site for cyclosporin A was in the C-terminal half of the protein. This cyclosporin A binding site was further characterized with chemical agents (N-chlorosuccinimide, cyanogen bromide, and 2-nitro-5-thiocyanobenzoate). These three chemical agents established a proteolytic profile of P-glycoprotein for fragments photolabeled with cyclosporin A and for fragments that contained the C494 and C219 epitopes. The smallest fragments generated by these chemical agents include the transmembrane domains (TMs) 10, 11, and 12 of P-glycoprotein. When the fragments generated by these chemical agents are aligned, the region that binds cyclosporin A is reduced to the 953-1007 residues. These combined results suggest that the major binding site of cyclosporin A occurs between the end of TM 11 and the end of TM 12. PMID:9922180

Demeule, M; Laplante, A; Murphy, G F; Wenger, R M; Béliveau, R

1998-12-22

192

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

193

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

Science.gov (United States)

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 compared with that of ADR alone, as determined using an MTT assay. Flow cytometric analysis revealed that germacrone promoted cell apoptosis in a dose-dependent manner, whilst treatment with germacrone plus ADR enhanced the apoptotic effect synergistically. Furthermore, the results from the western blot analysis demonstrated that augmenting ADR treatment with germacrone resulted in a reduction of anti-apoptotic protein expression levels (bcl-2) and enhancement of pro-apoptotic protein expression levels (p53 and bax) in MCF-7/ADR cells compared with the levels achieved by treatment with ADR alone. In addition, germacrone significantly reduced the expression of P-glycoprotein via the inhibition of the multidrug resistance 1 (MDR1) gene promoter. These findings demonstrate that germacrone has a critical role against MDR and may be a novel MDR reversal agent for breast cancer chemotherapy. PMID:25289068

Xie, Xiao-Hong; Zhao, Hong; Hu, Yuan-Yuan; Gu, Xi-Dong

2014-11-01

194

New natural sesquiterpenes as modulators of daunomycin resistance in a multidrug-resistant Leishmania tropica line.  

Science.gov (United States)

The effects produced by nine dihydro-beta-agarofuran sesquiterpenes isolated from Crossopetalum tonduzii (1-8) and Maytenus macrocarpa (9) (Celastraceae) on the reversion of the resistant phenotype on a multidrug-resistant Leishmania line and their binding to recombinant C-terminal nucleotide-binding domain of Leishmania P-glycoprotein-like transporter were studied. The structures of the new compounds (1-5) were elucidated by spectroscopic methods, including (1)H-(13)C heteronuclear correlation (HMQC), long-range correlation spectra with inversal detection (HMBC), ROESY experiments, and chemical correlations. The absolute configuration of one of them (1) was determined by CD studies. The structure-activity relationship is discussed. PMID:10543882

Pérez-Victoria, J M; Tincusi, B M; Jiménez, I A; Bazzocchi, I L; Gupta, M P; Castanys, S; Gamarro, F; Ravelo, A G

1999-10-21

195

Ceramide and glucosylceramide upregulate expression of the multidrug resistance gene MDR1 in cancer cells  

OpenAIRE

In the present study we used human breast cancer cell lines to assess the influence of ceramide and glucosylceramide (GC) on expression of MDR1, the multidrug resistance gene that codes for P-glycoprotein (P-gp), because GC has been shown to be a substrate for P-gp. Acute exposure (72 h) to C8-ceramide (5 µg/ml culture medium), a cell-permeable ceramide, increased MDR1 mRNA levels by 3-and 5-fold in T47D and in MDA-MB-435 cells, respectively. Acute exposure of MCF-7 and MDA-MB-231 cells to C...

Gouaze?-andersson, Vale?rie; Yu, Jing Y.; Kreitenberg, Adam J.; Bielawska, Alicja; Giuliano, Armando E.; Cabot, Myles C.

2007-01-01

196

Multidrug resistance 1 gene expression and AgNOR in childhood acute leukemias  

OpenAIRE

The multidrug resistance 1 (MDR1) gene product, P-glycoprotein (Pgp/p170) is a membrane protein, which acts as an ATP dependant efflux pump that expels a wide variety of organic compounds including chemotherapeutic agents from the cell. Pgp over expression has been demonstrated to be linked with poor treatment outcome and poor prognosis in a number of malignant tumors. AgNORs is a simple, reliable and inexpensive method of evaluating the proliferative activity of a tumor. We have studied MDR1...

Balamurugan, S.; Sugapriya, D.; Shanthi, P.; Thilaka, V.; Venkatadesilalu, S.; Pushpa, V.; Madhavan, M.

2007-01-01

197

Selective modulation of P-glycoprotein activity by steroidal saponines from Paris polyphylla.  

Science.gov (United States)

Bio-guided fractionation of the roots of Paris polyphylla (Trilliaceae), based on inhibition of P-glycoprotein-mediated daunorubicin efflux in K562/R7 cell line, led to isolation and identification of the three saponins 3-O-Rha(1-->2)[Ara(1-->4)]Glc-pennogenine, gracillin and polyphyllin D, and the two ecdysteroids 20-hydroxyecdysone and pinnatasterone. These compounds were tested for multidrug reversion on P-glycoprotein (ABCB1) with both drug-selected and transfected cell lines, and also on Breast Cancer Resistance Protein (BCRP/ABCG2). By contrast to a weak efficiency on BCRP, the three saponins displayed significant effects as inhibitors of P-glycoprotein-mediated drug efflux. PMID:18940238

Nguyen, Van Thi Bao; Darbour, Nicole; Bayet, Christine; Doreau, Agnès; Raad, Imad; Phung, Binh Hoa; Dumontet, Charles; Di Pietro, Attilio; Dijoux-Franca, Marie-Geneviève; Guilet, David

2009-01-01

198

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

199

Anthracyclines, proteasome activity and multi-drug-resistance  

OpenAIRE

Abstract Background P-glycoprotein is responsible for the ATP-dependent export of certain structurally unrelated compounds including many chemotherapeutic drugs. Amplification of P-glycoprotein activity can result in multi-drug resistance and is a common cause of chemotherapy treatment failure. Therefore, there is an ongoing search for inhibitors of P-glycoprotein. Observations that cyclosporin A, and certain other substances, inhibit both the proteasome and P-glycoprotein le...

Pajonk Frank; McBride William H; Fekete Mirela R

2005-01-01

200

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2014-01-15

201

The stabilisation of purified, reconstituted P-glycoprotein by freeze drying with disaccharides ?  

OpenAIRE

The drug efflux pump P-glycoprotein (P-gp) (ABCB1) confers multidrug resistance, a major cause of failure in the chemotherapy of tumours, exacerbated by a shortage of potent and selective inhibitors. A high throughput assay using purified P-gp to screen and characterise potential inhibitors would greatly accelerate their development. However, long-term stability of purified reconstituted ABCB1 can only be reliably achieved with storage at ?80 °C. For example, at 20 °C, the activity of ABC...

Heikal, Adam; Box, Karl; Rothnie, Alice; Storm, Janet; Callaghan, Richard; Allen, Marcus

2008-01-01

202

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

203

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

204

Role of intestinal P-glycoprotein in the plasma and fecal disposition of docetaxel in humans  

OpenAIRE

Multidrug resistance (MDR)-1-P-glycoprotein (P-gp) is a drug-transporting protein that is abundantly present in biliary ductal cells and epithelial cells lining the gastrointestinal tract. Here, we have determined the role of P-gp in the metabolic disposition of the antineoplastic agent docetaxel (Taxotere) in humans. Pharmacokinetic profiles were evaluated in five cancer patients receiving treatment cycles with docetaxel alone ...

Zuylen, L.; Verweij, J.; Nooter, K.; Brouwer, E.; Stoter, G.; Sparreboom, A.

2000-01-01

205

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 h...

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

2009-01-01

206

Expression of P-glycoprotein in hepatocellular carcinoma: a potential marker of prognosis.  

OpenAIRE

AIMS: (1) To investigate the immunohistochemical expression of the multidrug resistance gene (MDR1) product P-glycoprotein in histological samples from 31 hepatocellular carcinomas (HCCs); and (2) to correlate the results with cell proliferation, p53 expression, the disease-free interval, and cumulative patient survival. METHODS: C219 (a monoclonal antibody), CM-1 (a polyclonal rabbit anti-human antibody) and PC10 (a monoclonal mouse anti-human antibody) were used to detect expression of P-gl...

Soini, Y.; Virkaja?rvi, N.; Raunio, H.; Pa?a?kko?, P.

1996-01-01

207

The Reversal Effects of 3-Bromopyruvate on Multidrug Resistance In Vitro and In Vivo Derived from Human Breast MCF-7/ADR Cells  

Science.gov (United States)

Purpose P-glycoprotein mediated efflux is one of the main mechanisms for multidrug resistance in cancers, and 3-Bromopyruvate acts as a promising multidrug resistance reversal compound in our study. To test the ability of 3-Bromopyruvate to overcome P-glycoprotein-mediated multidrug resistance and to explore its mechanisms of multidrug resistance reversal in MCF-7/ADR cells, we evaluate the in vitro and in vivo modulatory activity of this compound. Methods The in vitro and in vivo activity was determined using the MTT assay and human breast cancer xenograft models. The gene and protein expression of P-glycoprotein were determined using real-time polymerase chain reaction and the Western blotting technique, respectively. ABCB-1 bioactivity was tested by fluorescence microscopy, multi-mode microplate reader, and flow cytometry. The intracellular levels of ATP, HK-II, and ATPase activity were based on an assay kit according to the manufacturer’s instructions. Results 3-Bromopyruvate treatment led to marked decreases in the IC50 values of selected chemotherapeutic drugs [e.g., doxorubicin (283 folds), paclitaxel (85 folds), daunorubicin (201 folds), and epirubicin (171 folds)] in MCF-7/ADR cells. 3-Bromopyruvate was found also to potentiate significantly the antitumor activity of epirubicin against MCF-7/ADR xenografts. The intracellular level of ATP decreased 44%, 46% in the presence of 12.5.25 µM 3-Bromopyruvate, whereas the accumulation of rhodamine 123 and epirubicin (two typical P-glycoprotein substrates) in cells was significantly increased. Furthermore, we found that the mRNA and the total protein level of P-glycoprotein were slightly altered by 3-Bromopyruvate. Moreover, the ATPase activity was significantly inhibited when 3-Bromopyruvate was applied. Conclusion We demonstrated that 3-Bromopyruvate can reverse P-glycoprotein-mediated efflux in MCF-7/ADR cells. Multidrug resistance reversal by 3-Bromopyruvate occurred through at least three approaches, namely, a decrease in the intracellular level of ATP and HK-II bioactivity, the inhibition of ATPase activity, and the slight decrease in P-glycoprotein expression in MCF-7/ADR cells. PMID:25372840

Yuan, Weiqi; Wu, Baojian; Wang, Hao; Liu, Guangquan; Wang, Xiaoxiong; Du, Jun; Cai, Shaohui

2014-01-01

208

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

Science.gov (United States)

Triclabendazole (TCBZ) is widely used for control of Fasciola hepatica (liver fluke) in animals and humans and resistance to this drug is now widespread. However, the mechanism of resistance to TCBZ is not known. A T687G single nucleotide polymorphism (SNP) in a P-glycoprotein gene was proposed as a molecular marker for TCBZ resistance in F. hepatica (Wilkinson et al., 2012). We analyzed this Pgp gene from TCBZ-susceptible and TCBZ-resistant populations from Australia to determine if the SNP was a marker for TCBZ resistance. From the 21 parasites studied we observed 27 individual haplotypes in the Pgp sequences which comprised seven haplotypic groups (A-G), with haplotypes A and B representing 81% of the total observed. The T687G SNP was not observed in either of the resistant or susceptible populations. We conclude that the T687G SNP in this Pgp gene is not associated with TCBZ resistance in these Australian F. hepatica populations and therefore unlikely to be a universal molecular marker for TCBZ resistance. PMID:25481750

Elliott, Timothy P; Spithill, Terry W

2014-11-01

209

Multidrug resistance in patients with osteoarticular tuberculosis  

Directory of Open Access Journals (Sweden)

Full Text Available This paper describes prevalence of multidrug resistant tuberculosis (MDR TB among 285 patients treated in clinic of National Center for TB Problems (Kazakhstan during 2007-2009. Data were obtained through clinical examination of patients and bacteriological culture investigation of postoperative material. The drug resistance in patients with OAT in 54.0% was confirmed on the base of microbiological investigation (culturing on Lowenstein-Jensen medium, and in 12.6% clinical resistance took place. The relatively high multidrug resistance revealed in patients with OAT is connected to the thorough sampling of the pathological material intraoperatively.

Layla Amanzholova

2011-04-01

210

The effectiveness of annonaceous acetogenins against multidrug -resistant tumor cells, and, the bioactivity-directed fractionation of the unripe fruit of {\\it Persea americana\\/}  

OpenAIRE

The problem of multidrug resistance (MDR)--wherein cancer cells become resistant to structurally unrelated antineoplastic agents--was approached by investigating the hypothesis that the biochemical difference between MDR and parental cancer cells, i.e., the ATP-dependent P-glycoprotein (P-gp), results in a higher demand for ATP in the MDR cancer cells. Therefore, the acetogenins, which are biologically active natural products that have a potent ability to decrease ATP levels, were investigate...

Oberlies, Nicholas Hunter

1997-01-01

211

Detection of multidrug resistance using molecular nuclear technique  

Energy Technology Data Exchange (ETDEWEB)

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

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

2004-04-01

212

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

Directory of Open Access Journals (Sweden)

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

213

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

Directory of Open Access Journals (Sweden)

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

214

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

Science.gov (United States)

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. PMID:25516824

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

2014-12-01

215

The multidrug resistance phenotype: 31P nuclear magnetic resonance characterization and 2-deoxyglucose toxicity.  

Science.gov (United States)

In order to identify changes in 31P nuclear magnetic resonance (NMR) spectra associated with multiple drug resistance (MDR), a number of wild type and drug-resistant cancer cell lines were studied. The resistant cells included cells selected with various drugs, mainly Adriamycin, as well as cells transfected with the human multidrug resistance gene (MDR1 gene), which encodes P-glycoprotein. In most cases, 31P NMR spectra were significantly different from those of parental, drug-sensitive lines. The spectra of resistant cells generally indicated increased levels of ATP and phosphocreatine in the cytoplasm. These changes are compatible with the increased glucose utilization rate previously described for resistant cells. Major changes were also observed in the levels of glycerophosphocholine and glycerophosphoethanolamine. Changes in cellular metabolism reflected by 31P NMR spectra depend on the drug used to select the cells for MDR. The direction of these changes was not consistent for all cell lines studied and could not be directly attributed to expression of P-glycoprotein, suggesting that the changes may be related to alterations in metabolism and membrane function associated with other mechanisms of MDR. The results demonstrate the suitability of 31P NMR for studies of biochemical changes associated with MDR. The toxicity of 2-deoxyglucose, a glucose antimetabolite, was investigated in addition to the NMR studies and was found to be consistently higher in multidrug-resistant cells than in the parental drug-sensitive lines. For MCF-7 breast cancer cells, where several sublines with different levels of resistance were available, the toxicity was highest for the most resistant lines. PMID:1998955

Kaplan, O; Jaroszewski, J W; Clarke, R; Fairchild, C R; Schoenlein, P; Goldenberg, S; Gottesman, M M; Cohen, J S

1991-03-15

216

Screening Compounds with a Novel High-Throughput ABCB1-Mediated Efflux Assay Identifies Drugs with Known Therapeutic Targets at Risk for Multidrug Resistance Interference  

OpenAIRE

ABCB1, also known as P-glycoprotein (P-gp) or multidrug resistance protein 1 (MDR1), is a membrane-associated multidrug transporter of the ATP-binding cassette (ABC) transporter family. It is one of the most widely studied transporters that enable cancer cells to develop drug resistance. Reliable high-throughput assays that can identify compounds that interact with ABCB1 are crucial for developing new therapeutic drugs. A high-throughput assay for measuring ABCB1-mediated calcein AM efflux wa...

Ansbro, Megan R.; Shukla, Suneet; Ambudkar, Suresh V.; Yuspa, Stuart H.; Li, Luowei

2013-01-01

217

Synthesis and structure-activity evaluation of isatin-?-thiosemicarbazones with improved selective activity towards multidrug-resistant cells expressing P-glycoproteina  

OpenAIRE

Cancer multidrug resistance (MDR) mediated by ATP-binding cassette (ABC) transporters presents a significant unresolved clinical challenge. One strategy to resolve MDR is to develop compounds that selectively kill cells over-expressing the efflux transporter P-glycoprotein (MDR1, P-gp, ABCB1). We have previously reported structure-activity studies based around the lead compound NSC73306 (1, 1-isatin-4-(4?-methoxyphenyl)-3-thiosemicarbazone, 4.3-fold selective). Here we sought to extend this...

Hall, Matthew D.; Brimacombe, Kyle R.; Varonka, Matthew S.; Pluchino, Kristen M.; Monda, Julie K.; Li, Jiayang; Walsh, Martin J.; Boxer, Matthew B.; Warren, Timothy H.; Fales, Henry M.; Gottesman, Michael M.

2011-01-01

218

Expression of P-glycoprotein-mediated drug resistance in CHO cells surviving a single X-ray dose of 30 Gy  

International Nuclear Information System (INIS)

The authors reported previously that Chinese hamster ovary (CHO) cells surviving exposure to repeated doses of 9 Gy of X-irradiation in vitro expressed a multiple drug resistance phenotype characterized by cross-resistance to epipodophyllotoxins and to Vinca alkaloids, and by P-glycoprotein (Pgp) overexpression. They now show that exposure of these CHO cells to a single 30-Gy X-ray dose similarly resulted in the survivors expressing resistance to vincristine and to etoposide and overexpressing Pgp. In agreement with data obtained on cells which received repeated X-ray exposures, this Pgp overexpression occurred in the absence of any significant elevation of Pgp mRNA. However, the reduced ability to accumulate rhodamine 123 identified in these sublines, and the ability of verapamil to reverse this accumulation defect, implies that the Pgp which was overexpressed was functional. (author)

219

Overcoming of P-glycoprotein mediated vincristine resistance of L1210/VCR mouse leukemic cells could be induced by pentoxifylline but not by theophylline and caffeine  

International Nuclear Information System (INIS)

Effects of xanthine derivatives (pentoxifylline (PTX), caffeine, theophylline, 1-methyl-3-isobutylxanthine) on P-glycoprotein mediated vincristine resistance of L1210/VCR mouse leukemic cell sub-line were studied. From the applied xanthines only PTX was found to reverse the vincristine resistance of the above cells. Moreover, only PTX, but not other xanthine, increased the accumulation of [3H]vincristine by L1210/VCR cells. Thus it may be concluded that PTX-induced reversal of vincristine (VCR) resistance could not be explained from the point of known pharmacological effects of PTX that are common for other xanthines such as inhibition of phosphodiesterase activity, calcium mobilizing effect, inhibition of tumor necrosis factor ? (TNF), etc. (author)

220

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-08-15

221

Multidrug resistant yeasts in synanthropic wild birds  

OpenAIRE

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...

Somanath Sushela; Mohandas Kavitha; Lord Alexander; Ambu Stephen

2010-01-01

222

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

Energy Technology Data Exchange (ETDEWEB)

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 tumor types known to be relatively responsive to chemotherapy.

Noonan, K.E.; Beck, C.; Holzmayer, T.A.; Chin, J.E.; Roninson, I.B. (Univ. of Illinois, Chicago (USA)); Wunder, J.S.; Andrulis, I.L. (Mount Sinai Hospital, Toronto, Ontario (Canada)); Gazdar, A.F. (National Cancer Inst., Bethesda, MD (USA)); Willman, C.L.; Griffith, B. (Univ. of New Mexico, Albuquerque (USA)); Von Hoff, D.D. (Univ. of Texas, San Antonio (USA))

1990-09-01

223

Multidrug-resistant Tuberculosis in Central Asia  

OpenAIRE

Multidrug-resistant tuberculosis (MDR-TB) has emerged as a major threat to TB control, particularly in the former Soviet Union. To determine levels of drug resistance within a directly observed treatment strategy (DOTS) program supported by Médecins Sans Frontières in two regions in Uzbekistan and Turkmenistan, Central Asia, we conducted a cross-sectional survey of smear-positive TB patients in selected districts of Karakalpakstan (Uzbekistan) and Dashoguz (Turkmenistan). High levels of MDR...

Cox, Helen Suzanne; Orozco, Juan Daniel; Male, Roy; Ruesch-gerdes, Sabine; Falzon, Dennis; Small, Ian; Doshetov, Darebay; Kebede, Yared; Aziz, Mohammed

2004-01-01

224

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

Energy Technology Data Exchange (ETDEWEB)

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 {sup 99m}Tc-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 {sup 99m}Tc-tetrofosmin was remarkably lower in MCF-7/Adr than in MCF-7. The uptake of {sup 99m}Tc-tetrofosmin in MCF-7/Adr exhibited a 4, 13, 16 fold increase in the presence of 200, 400 and 500 {mu}g/ml of tea polyphenol respectively. The uptake of {sup 99m}Tc-tetrofosmin in MCF-7/Adr exhibited only a 4-fold increase in the presence of 200 {mu}M of quinidine. Immunocytochemistry can detect P-glycoprotein expression level qualitatively. 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.

Zhu Aizhi E-mail: zhuaizhi@263.net; Wang Xiangyun; Guo Zhenquan

2001-08-01

225

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 tra...

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

2010-01-01

226

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

OpenAIRE

P-glycoprotein (Pgp), encoded by the multidrug resistance 1 (MDR1) gene, is an efflux transporter and plays an important role in pharmacokinetics. In this study, we demonstrated that the pokemon promoter activity, the pokemon mRNA and protein expression can be significantly inhibited by Pgp. Chromatin immunoprecipitation assay showed that Pgp can bind the pokemon prompter to repress pokemon transcription activity. Furthermore, Pgp regulated pokemon transcription activity through expression of...

Wei Xu; Yuyang Jiang; Xuyu Zu; Shengnan He; Zhenhua Xie; Feng Liu

2010-01-01

227

In silico structure-based screening of versatile P-glycoprotein inhibitors using polynomial empirical scoring functions  

OpenAIRE

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&n...

Shityakov S; Förster C

2014-01-01

228

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

229

The Multidrug Resistance 1 Gene Abcb1 in Brain and Placenta: Comparative Analysis in Human and Guinea Pig  

OpenAIRE

The Multidrug Resistance 1 (MDR1; alternatively ABCB1) gene product P-glycoprotein (P-gp), an ATP binding cassette transporter, extrudes multiple endogenous and exogenous substrates from the cell, playing an important role in normal physiology and xenobiotic distribution and bioavailability. To date, the predominant animal models used to investigate the role of P-gp have been the mouse and rat, which have two distinct genes, Abcb1a and Abcb1b. In contrast, the human has a single gene, ABCB1, ...

Pappas, Jane J.; Petropoulos, Sophie; Suderman, Matthew; Iqbal, Majid; Moisiadis, Vasilis; Turecki, Gustavo; Matthews, Stephen G.; Szyf, Moshe

2014-01-01

230

Proteome analysis of multidrug-resistant, breast cancer–derived microparticles  

Science.gov (United States)

Cancer multidrug resistance (MDR) occurs when cancer cells evade the cytotoxic actions of chemotherapeutics through the active efflux of drugs from within the cells. Our group have previously demonstrated that multidrug-resistant breast cancer cells spontaneously shed microparticles (MPs) and that these MPs can transfer resistance to drug-responsive cells and confer MDR on those cells in as little as 4 h. Furthermore, we also showed that, unlike MPs derived from leukaemia cells, breast cancer–derived MPs display a tissue selectivity in the transfer of P-glycoprotein (P-gp), transferring the resistance protein only to malignant breast cells. This study aims to define the proteome of breast cancer–derived MPs in order to understand the differences in protein profiles between those shed from drug-resistant versus drug-sensitive breast cancer cells. In doing so, we detail the protein cargo required for the intercellular transfer of MDR to drug-sensitive recipient cells and the factors governing the transfer selectivity to malignant breast cells. We describe the first proteomic analysis of MPs derived from human breast cancer cells using SDS PAGE and liquid chromatography–tandem mass spectrometry (LC/MS/MS), in which we identify 120 unique proteins found only in drug-resistant, breast cancer–derived MPs. Our results demonstrate that the MP-mediated transfer of P-gp to recipient cells occurs alongside CD44; the Ezrin, Radixin and Moesin protein family (ERM); and cytoskeleton motor proteins within the MP cargo. PMID:25206959

Pokharel, Deep; Padula, Matthew P.; Lu, Jamie F.; Tacchi, Jessica L.; Luk, Frederick; Djordjevic, Steven P.; Bebawy, Mary

2014-01-01

231

Proteome analysis of multidrug-resistant, breast cancer-derived microparticles.  

Science.gov (United States)

Cancer multidrug resistance (MDR) occurs when cancer cells evade the cytotoxic actions of chemotherapeutics through the active efflux of drugs from within the cells. Our group have previously demonstrated that multidrug-resistant breast cancer cells spontaneously shed microparticles (MPs) and that these MPs can transfer resistance to drug-responsive cells and confer MDR on those cells in as little as 4 h. Furthermore, we also showed that, unlike MPs derived from leukaemia cells, breast cancer-derived MPs display a tissue selectivity in the transfer of P-glycoprotein (P-gp), transferring the resistance protein only to malignant breast cells. This study aims to define the proteome of breast cancer-derived MPs in order to understand the differences in protein profiles between those shed from drug-resistant versus drug-sensitive breast cancer cells. In doing so, we detail the protein cargo required for the intercellular transfer of MDR to drug-sensitive recipient cells and the factors governing the transfer selectivity to malignant breast cells. We describe the first proteomic analysis of MPs derived from human breast cancer cells using SDS PAGE and liquid chromatography-tandem mass spectrometry (LC/MS/MS), in which we identify 120 unique proteins found only in drug-resistant, breast cancer-derived MPs. Our results demonstrate that the MP-mediated transfer of P-gp to recipient cells occurs alongside CD44; the Ezrin, Radixin and Moesin protein family (ERM); and cytoskeleton motor proteins within the MP cargo. PMID:25206959

Pokharel, Deep; Padula, Matthew P; Lu, Jamie F; Tacchi, Jessica L; Luk, Frederick; Djordjevic, Steven P; Bebawy, Mary

2014-01-01

232

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

233

E.typographi multidrug resistant efflux pumps  

OpenAIRE

The aim of the study was to determine activity of MDR pumps in yet uninvestigated E. typography cells discovered in bark beetle gut microflora. The cells were exposed to myrcene anintegral part essential oils. The Investigations were carried out at department of Biochemistry of VMU using potentiometric analysis of a flow through the cell envelope of an universal substrate of multidrug resistant pumps substrate TPP+ions. Reactions of E. typography cells to myrcene were compared with effects of...

Bagdonas, Vytenis

2014-01-01

234

Reversal of multidrug resistance by surfactants.  

OpenAIRE

Cremophor EL, a pharmacologically inactive solubilising agent, has been shown to reverse multidrug resistance (MDR). Using flow cytometric evaluation of equilibrium intracellular levels of daunorubicin (DNR), we found that eight other surface active agents will also reverse MDR. All the active detergents contain polyethoxylated moieties but have no similarities in their hydrophobic components. The properties of three polyethoxylated surfactants that showed the lowest toxicities, Cremophor, Tw...

Woodcock, D. M.; Linsenmeyer, M. E.; Chojnowski, G.; Kriegler, A. B.; Nink, V.; Webster, L. K.; Sawyer, W. H.

1992-01-01

235

The major vault protein (MVP), a new multidrug resistance associated protein, is frequently expressed in multiple myeloma.  

Science.gov (United States)

The major vault protein (MVP), a ribonucleoprotein complex which mediates the transport of xenobiotic toxins, has been implicated in multidrug resistance (MDR) not mediated by p-glycoprotein (P-gp) or multidrug resistance related protein (MRP). We evaluated, via immunohistochemistry, the presence of MVP in plasma cells of myeloma patients. Among 73 patients registered with the Southwest Oncology Group (SWOG), 52 patients (74%) were positive for MVP. The presence of MVP and P-gp were significantly associated (p 5%) was significantly associated with shorter OS (log rank p-value = 0.0002). The collective work indicates that MVP protein is common and abundant in myeloma with potential relevance to therapeutic response. PMID:10439368

Rimsza, L M; Campbell, K; Dalton, W S; Salmon, S; Willcox, G; Grogan, T M

1999-07-01

236

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.

237

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

238

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

239

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

240

PTRF/cavin-1 is essential for multidrug resistance in cancer cells.  

Science.gov (United States)

Since detergent-resistant lipid rafts play important roles in multidrug resistance (MDR), their comprehensive proteomics could provide new insights to understand the underlying molecular mechanism of MDR in cancer cells. In the present work, lipid rafts were isolated from MCF-7 and adriamycin-resistant MCF-7/ADR cells and their proteomes were analyzed by label-free quantitative proteomics. Polymerase I and transcript release factor (PTRF)/cavin-1 was measured to be upregulated along with multidrug-resistant P-glycoprotein, caveolin-1, and serum deprivation protein response/cavin-2 in the lipid rafts of MCF-7/ADR cells. PTRF knockdown led to reduction in the amount of lipid rafts on the surface of MCF7/ADR cells as determined by cellular staining with lipid raft-specific dyes such as S-laurdan2 and FITC-conjugated cholera toxin B. PTRF knockdown also reduced MDR in MCF-7/ADR cells. These data indicate that PTRF is necessary for MDR in cancer cells via the fortification of lipid rafts. PMID:23214712

Yi, Jae-Sung; Mun, Dong-Gi; Lee, Hyun; Park, Jun-sub; Lee, Jung-Woo; Lee, Jae-Seon; Kim, Su-Jin; Cho, Bong-Rae; Lee, Sang-Won; Ko, Young-Gyu

2013-02-01

241

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

242

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

243

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  

International Nuclear Information System (INIS)

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. 99mTc-MIBI efflux rates were measured using a gamma camera in three Brca1 -/-; p53 -/- 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 99mTc-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.)

244

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)

245

Identification of an ABCB1 (P-glycoprotein)-positive carfilzomib-resistant myeloma subpopulation by the pluripotent stem cell fluorescent dye CDy1.  

Science.gov (United States)

Multiple myeloma (MM) is characterized by the malignant expansion of differentiated plasma cells. Although many chemotherapeutic agents display cytotoxic activity toward MM cells, patients inevitably succumb to their disease because the tumor cells become resistant to the anticancer drugs. The cancer stem cell hypothesis postulates that a small subpopulation of chemotherapy-resistant cancer cells is responsible for propagation of the tumor. Herein we report that efflux of the pluripotent stem cell dye CDy1 identifies a subpopulation in MM cell lines characterized by increased expression of P-glycoprotein, a member of the ABC (ATP-binding cassette) superfamily of transporters encoded by ABCB1. We also demonstrate that ABCB1-overexpressing MM cells are resistant to the second-generation proteasome inhibitor carfilzomib that recently received accelerated approval for the treatment of therapy-refractive MM by the U.S. Food and Drug Administration. Moreover, increased resistance to carfilzomib in sensitive MM cells following drug selection was associated with upregulation of ABCB1 cell-surface expression which correlated with increased transporter activity as measured by CDy1 efflux. We further show that chemosensitization of MM cells to carfilzomib could be achieved in vitro by cotreatment with vismodegib, a hedgehog pathway antagonist which is currently in MM clinical trials. CDy1 efflux may therefore be a useful assay to determine whether high expression of ABCB1 is predictive of poor clinical responses in MM patients treated with carfilzomib. Our data also suggest that inclusion of vismodegib might be a potential strategy to reverse ABCB1-mediated drug resistance should it occur. PMID:23475625

Hawley, Teresa S; Riz, Irene; Yang, Wenjing; Wakabayashi, Yoshiyuki; Depalma, Louis; Chang, Young-Tae; Peng, Weiqun; Zhu, Jun; Hawley, Robert G

2013-04-01

246

Poloxamer 407/TPGS mixed micelles for delivery of gambogic acid to breast and multidrug-resistant cancer  

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Full Text Available Vipin Saxena, M Delwar HussainDepartment of Pharmaceutical Sciences, Irma Lerma Rangel College of Pharmacy, Texas A&M Health Science Center, Kingsville, TX, USABackground: Delivery of a high concentration of anticancer drugs specifically to cancer cells remains the biggest challenge for the treatment of multidrug-resistant cancer. Poloxamers and D-?-Tocopheryl polyethylene glycol 1000 succinate (TPGS are known inhibitors of P-glycoprotein (P-gp. Mixed micelles prepared from Poloxamer 407 and TPGS may increase the therapeutic efficacy of the drug by delivering high concentrations inside the cells and inhibiting P-gp. Gambogic acid (GA is a naturally derived novel anticancer agent, but poor solubility and toxic side effects limit its use. In this study, we have developed Poloxamer 407 and TPGS mixed micelle-encapsulating GA for the treatment of breast and multidrug-resistant cancer.Methods: GA-loaded Poloxamer 407/TPGS mixed micelles were prepared using a thin film hydration method, and their physicochemical properties were characterized. Cellular accumulation and cytotoxicity of the GA-loaded Poloxamer 407/TPGS mixed micelles were studied in breast cancer cells, MCF-7 cells, and multidrug-resistant NCI/ADR-RES cells.Results: The diameter of GA-loaded Poloxamer 407/TPGS mixed micelles was about 17.4 ± 0.5 nm and the zeta potential -13.57 mV. The entrapment efficiency of GA was 93.1% ± 0.5% and drug loading was about 9.38% ± 0.29%. Differential scanning calorimetry and X-ray powder diffraction studies confirmed that GA is encapsulated by the polymers. The in vitro release studies showed that mixed micelles sustained the release of GA for more than 4 days. Results from cellular uptake studies indicated that GA-loaded Poloxamer 407/TPGS mixed micelles had increased cellular uptake of GA in NCI/ADR-RES cells. Cytotoxicity of GA-loaded Poloxamer 407/TPGS mixed micelles was found to be 2.9 times higher in multidrug-resistant NCI/ADR-RES cells, and 1.6 times higher in MCF-7 cells, as compared with unencapsulated GA.Conclusion: This study suggests that Poloxamer 407/TPGS mixed micelles can be used as a delivery system for GA to treat breast and multidrug-resistant cancer.Keywords: gambogic acid, Poloxamer 407, TPGS, P-glycoprotein, multidrug resistance, breast cancer

Hussain MD

2012-02-01

247

Up-regulation of P-glycoprotein confers acquired resistance to 6-mercaptopurine in human chronic myeloid leukemia cells  

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To investigate the mechanisms of cellular resistance to 6-mercaptopurine (6-MP) in chronic myeloid leukemia (CML), a 6-MP resistant cell line (K562-MP5) was established by stepwise selection of the CML cell line (K562). The results of the drug sensitivity analysis of the K562-MP5 cell line revealed the cells to be 339-fold more resistant to 6-MP compared with the parental K562 cells. K562-MP5 cells exhibited decreased accumulation and increased efflux of [14C]6-MP and its metabolites. In addi...

Peng, Xing-xiang; Shi, Zhi; Tiwari, Amit K.; Damaraju, Vijaya L.; Fu, Liwu; Cass, Carol E.; Ashby, Charles R.; Kruh, Gary D.; Chen, Zhe-sheng

2011-01-01

248

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  

OpenAIRE

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 ...

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

2012-01-01

249

SmeDEF Multidrug Efflux Pump Contributes to Intrinsic Multidrug Resistance in Stenotrophomonas maltophilia  

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Stenotrophomonas maltophilia is an emerging nosocomial pathogen that displays high-level intrinsic resistance to a variety of structurally unrelated antimicrobial agents. Efflux mechanisms are known to contribute to acquired multidrug resistance in this organism, and indeed, one such multidrug efflux system, SmeDEF, was recently identified. Still, the importance of SmeDEF to intrinsic antibiotic resistance in S. maltophilia had not yet been determined. Reverse transcription-PCR confirmed expr...

Zhang, Li; Li, Xian-zhi; Poole, Keith

2001-01-01

250

?Bedaquiline for multidrug-resistant tuberculosis.  

Science.gov (United States)

Resistance to drugs used to treat tuberculosis (TB) is a major public health problem that threatens progress made in TB management and control worldwide. It may result from improper use of antibiotics, including prescription of non-standard treatment regimens and poor adherence to drug therapy. Multidrug-resistant TB (MDR-TB) is defined as resistance to isoniazid and rifampicin, with or without resistance to other first-line drugs. Extensively drug-resistant TB (XDR-TB) refers to resistance to at least isoniazid and rifampicin, and to any fluoroquinolone, and to any of the three second-line injectables ?(amikacin, capreomycin and kanamycin). In 2012, DTB discussed the investigation, management and treatment of patients with MDR- and XDR-TB. Earlier this year, ?bedaquiline (Sirturo) and ?delamanid (Deltyba) were authorised by the European Medicines Agency (EMA) under its 'conditional market authorisation' scheme for use as part of an appropriate combination regimen for pulmonary MDR-TB in adult patients "when an effective treatment regimen cannot otherwise be composed for reasons of resistance or tolerability." In this article, we review the evidence for bedaquiline in the management of MDR-TB. PMID:25395481

2014-11-01

251

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

252

From MDR to MXR : new understanding of multidrug resistance systems, their properties and clinical significance  

DEFF Research Database (Denmark)

The ATP binding cassette (ABC) superfamily of membrane transporters is one of the largest protein classes known, and counts numerous proteins involved in the trafficking of biological molecules across cell membranes. The first known human ABC transporter was P-glycoprotein (P-gp), which confers multidrug resistance (MDR) to anticancer drugs. In recent years, we have obtained an increased understanding of the mechanism of action of P-gp as its ATPase activity, substrate specificity and pharmacokinetic interactions have been investigated. This review focuses on the functional characterization of P-gp, as well as other ABC transporters involved in MDR: the family of multidrug-resistance-associated proteins (MRP1-7), and the recently discovered ABC half-transporter MXR (also known as BCRP, ABCP and ABCG2). We describe recent progress in the analysis of protein structure-function relationships, and consider the conceptual problem of defining and identifying substrates and inhibitors of MDR. An in-depth discussion follows of how coupling of nucleotide hydrolysis to substrate transport takes place, and we propose a scheme for the mechanism of P-gp function. Finally, the clinical correlations, both for reversal of MDR in cancer and for drug delivery, are discussed.

Litman, Thomas; Druley, T E

2001-01-01

253

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

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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. 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.

Chun, K. A.; Lee, J.; Chun, S. H.; Sohn, S. K.; Yi, C. K.; Lee, K. B. [College of Medicine, Kyungpook National Univ., Taegu (Korea, Republic of); Kim, J. H. [College of Medicine, Youngnam Univ., Taegu (Korea, Republic of)

1997-07-01

254

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

255

Disruption of vitellogenesis and spermatogenesis by triclabendazole (TCBZ) in a TCBZ-resistant isolate of Fasciola hepatica following incubation in vitro with a P-glycoprotein inhibitor.  

Science.gov (United States)

A study has been carried out to investigate whether the action of triclabendazole (TCBZ) against Fasciola hepatica is altered by inhibition of P-glycoprotein (Pgp)-linked drug efflux pumps. The Sligo TCBZ-resistant fluke isolate was used for these experiments and the Pgp inhibitor selected was R(+)-verapamil [R(+)-VPL]. In the first experiment, flukes were initially incubated for 2 h in R(+)-VPL (100 ? m), then incubated in R(+)-VPL+triclabendazole sulphoxide (TCBZ.SO) (50 ?g mL-1, or 133·1 ? m) until flukes ceased movement (at 9 h post-treatment). In a second experiment, flukes were incubated in TCBZ.SO alone and removed from the incubation medium following cessation of motility (after 15 h). In the third experiment, flukes were incubated for 24 h in R(+)-VPL on its own. Changes to the testis tubules and vitelline follicles following drug treatment and following Pgp inhibition were assessed by means of light microscope histology and transmission electron microscopy. Incubation of the Sligo isolate in either R(+)-VPL or TCBZ.SO on their own had a limited impact on the morphology of the two tissues. Greater disruption was observed when the drugs were combined, in terms of the block in development of the spermatogenic and vitelline cells and the apoptotic breakdown of the remaining cells. Sperm formation was severely affected and abnormal. Large spaces appeared in the vitelline follicles and synthesis of shell protein was disrupted. The results of this study support the concept of altered drug efflux in TCBZ-resistant flukes and indicate that drug transporters may play a role in the development of drug resistance. PMID:24889697

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

2014-07-01

256

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

Science.gov (United States)

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

257

Design real-time reversal of tumor multidrug resistance cleverly with shortened carbon nanotubes  

Directory of Open Access Journals (Sweden)

Full Text Available Pingping Wu,1 Shang Li,2 Haijun Zhang2 1Jiangsu Cancer Hospital, Nanjing, People’s Republic of China; 2Department of Oncology, Zhongda Hospital, Medical School, Southeast University, Nanjing, People’s Republic of ChinaAbstract: Multidrug resistance (MDR in tumors renders many currently available chemotherapeutic drugs ineffective. Research in nanobiotechnology-based therapeutic alternatives has provided innovative and promising strategies to overcome MDR. The aim of this study was to investigate whether the new strategy of a co-loaded reversal agent and chemotherapeutic drug with shortened carbon nanotubes (CNTs would show useful effects on the real-time reversal of tumor MDR. CNTs were cut and purified via ultrasonication and oxidative acid treatment to optimize their length for drug-delivery vehicles, then verapamil (Ver and doxorubicin (Dox were co-loaded on shortened CNTs (denoted as Ver/Dox/shortened CNTs, which acted as a drug delivery system. The multidrug resistant leukemia K562/A02 cells were treated with the denoted Ver/Dox/shortened CNTs. The real-time reversal of tumor MDR were evaluated by flow cytometer, 3-(4,5-Dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide assays, acridine orange/ethidium bromide staining, and Western blot analysis. In the same MDR tumor cells the new strategy of a co-loaded reversal agent and chemotherapeutic drug with CNTs could inhibit the function of P-glycoprotein in real-time by Ver as reversal agent, significantly increase the uptake of Dox, enhance the sensitivity of the MDR cancer cells to the chemotherapeutic agent, and induce apoptosis. It was therefore concluded that a co-loaded reversal agent and chemotherapeutic drug with shortened CNTs could have real-time reversal ability of MDR in tumors, which could represent a promising approach in cancer therapy.Keywords: multidrug resistance, carbon nanotubes, drug delivery system, tumor

Wu P

2014-12-01

258

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

International Nuclear Information System (INIS)

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, [11C]TPT, to evaluate the P-glycoprotein (Pgp)- and breast cancer resistance protein (BCRP)-mediated brain penetration of [11C]TPT using small-animal PET. Methods: [11C]TPT was synthesized by the reaction of a desmethyl precursor with [11C]CH3I. In vitro study using [11C]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 [11C]TPT was determined using small-animal PET and the dissection method in mice. Results: The transport of [11C]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-/-Bcrp1-/- mice, PET results indicated that the brain uptake of [11C]TPT was about two times higher than that in wild-type mice. Similarly, the brain penetration of [11C]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 t was maintained at a certain level after the injection of [11C]TPT, although the radioactivity in the blood decreased with time. Conclusions: We demonstrated the increase of brain penetration of [11C]TPT by deficiency and inhibition of Pgp and BCRP functions using small-animal PET in mice.

259

Reduced mRNA levels for the multidrug-resistance genes in cAMP-dependent protein kinase mutant cell lines.  

Science.gov (United States)

We have previously shown that in Chinese hamster ovary (CHO) cells, a mutant cell line with a defective regulatory subunit (RI) for the cAMP-dependent protein kinase (Abraham et al: Mol. Cell. Biol., 7:3098-3106, 1987), and a transfectant cell line expressing the same mutant kinase, showed increased sensitivity to a number of drugs that are known to be substrates for the multidrug transporter (P-glycoprotein). In the current study we have investigated the mechanism by which cAMP-dependent protein kinase controls drug resistance. We report here that the sensitivity of the kinase defective CHO cell lines to multiple drugs results from decreased RNA levels for the multidrug-resistance gene. Similar results were obtained with mouse Y1 adrenal cells. Wild-type Y1 cells had high levels of P-glycoprotein due to expression of both the mdr1b and mdr2 genes, whereas the cAMP-dependent protein kinase mutant Kin 8 cells had decreased RNA levels for these genes. A Kin 8 transfectant with restored cAMP-dependent protein kinase activity recovered mdr expression, indicating a cause and effect relationship between the protein kinase mutations and mdr expression. No changes in nuclear run-off assays could be detected, suggesting a non-transcriptional mechanism of regulation. Wild-type Y1 cells are more drug sensitive despite having higher levels of P-glycoprotein than the mutant cells. This paradoxical result may be explained by the higher rate of synthesis of steroids by the wild-type Y1 cells, which appear to be inhibitors of P-glycoprotein transport activity. PMID:1352302

Chin, K V; Chauhan, S S; Abraham, I; Sampson, K E; Krolczyk, A J; Wong, M; Schimmer, B; Pastan, I; Gottesman, M M

1992-07-01

260

Saturable Active Efflux by P-Glycoprotein and Breast Cancer Resistance Protein at the Blood-Brain Barrier Leads to Nonlinear Distribution of Elacridar to the Central Nervous System  

OpenAIRE

The study objective was to investigate factors that affect the central nervous system (CNS) distribution of elacridar. Elacridar inhibits transport mediated by P-glycoprotein (P-gp) and breast cancer resistance protein (Bcrp) and has been used to study the influence of transporters on brain distribution of chemotherapeutics. Adequate distribution of elacridar across the blood-brain barrier (BBB) and into the brain parenchyma is necessary to target tumor cells in the brain that overexpress tra...

Sane, Ramola; Agarwal, Sagar; Mittapalli, Rajendar K.; Elmquist, William F.

2013-01-01

261

Investigation of the role of glutamine-471 and glutamine-1114 in the two catalytic sites of P-glycoprotein.  

Science.gov (United States)

P-glycoprotein, also known as multidrug resistance protein, pumps drugs out of cells using ATP hydrolysis as the energy source. Glutamine-471 and the corresponding glutamine-1114 in the two catalytic sites of P-glycoprotein are conserved in ABC transporters. X-ray structures show that they lie close to the bound nucleotide. Proposed functional roles are (1) activation of the attacking water for ATP hydrolysis, (2) coordination of the essential Mg(2+) cofactor in Mg nucleotide, and (3) signal communication between catalytic site reaction chemistry and drug-binding sites. We made mutations Q471A, Q471E, Q1114A, and Q1114E in mouse MDR3 P-glycoprotein. Pure mutant and wild-type proteins were prepared and subjected to enzymatic and biochemical characterization. We conclude from the results that the primary role of this glutamine residue is in interdomain signal communication. Coordination of the Mg(2+) cofactor is not a critical functional role, neither is activation of the attacking water molecule, although an auxiliary role in positioning the water cannot be ruled out. We found that equivalent mutations (Ala or Glu) in either of the two P-glycoprotein catalytic sites produced the same effects, implying functional symmetry of the two sites. PMID:11009605

Urbatsch, I L; Gimi, K; Wilke-Mounts, S; Senior, A E

2000-10-01

262

Trends in multidrug-resistant tuberculosis  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english 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 pr [...] eviously 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; S. M. R. S., Usó; J., Marcondes-Machado.

263

Multidrug-resistant tuberculosis in pregnancy  

International Nuclear Information System (INIS)

This is a case report of 26 years old pregnant woman with multidrug-resistant tuberculosis (MDR TB), treated at outpatient department of New Delhi Tuberculosis (NDTB) Centre, India with second line agents. Before presentation at NDTB Centre, she had been treated with first line drugs for approximately one and-a-half-year, including category II re-treatment DOTS regimen under RNTCP. Patient conceived twice during her anti-TB treatment. The first one was during her category II treatment, when put on second line drugs. We describe congenital abnormalities documented in her second child exposed in-utero to second line anti-tubercular drugs with a brief review of treatment of MDR TB in pregnancy. (author)

264

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

265

Impact of P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2) gene dosage on plasma pharmacokinetics and brain accumulation of dasatinib, sorafenib, and sunitinib.  

Science.gov (United States)

Low brain accumulation of anticancer drugs due to efflux transporters may limit chemotherapeutic efficacy, necessitating a better understanding of the underlying mechanisms. P-glycoprotein (Abcb1a/1b) and breast cancer resistance protein (Abcg2) combination knockout mice often display disproportionately increased brain accumulation of shared drug substrates compared with single transporter knockout mice. Recently developed pharmacokinetic models could explain this phenomenon. To experimentally test these models and their wider relevance for tyrosine kinase inhibitors and other drugs, we selected dasatinib, sorafenib, and sunitinib because of their divergent oral availability and brain accumulation profiles: the brain accumulation of dasatinib is mainly restricted by Abcb1, that of sorafenib mainly by Abcg2, and that of sunitinib equally by Abcb1 and Abcg2. We analyzed the effect of halving the efflux activity of these transporters at the blood-brain barrier by generating heterozygous Abcb1a/1b;Abcg2 knockout mice and testing the plasma and brain levels of the drugs after oral administration at 10 mg/kg. Real-time reverse transcription-polymerase chain reaction analysis confirmed the ?2-fold decreased expression of both transporters in brain. Interestingly, whereas complete knockout of the transporters caused 24- to 36-fold increases in brain accumulation of the drugs, the heterozygous mice only displayed 1.6- to 1.9-fold increases of brain accumulation relative to wild-type mice. These results are well in line with the predictions of the pharmacokinetic models and provide strong support for their validity for a wider range of drugs. Moreover, retrospective analysis of fetal accumulation of drugs across the placenta in Abcb1a/1b heterozygous knockout pups suggests that these models equally apply to the maternal-fetal barrier. PMID:23843632

Tang, Seng Chuan; de Vries, Niels; Sparidans, Rolf W; Wagenaar, Els; Beijnen, Jos H; Schinkel, Alfred H

2013-09-01

266

Management of multidrug resistant bacterial endemic.  

Science.gov (United States)

The fight against multi-drug resistant Gram-negative bacilli (MDRGNB), especially extended-spectrum ?-lactamase producing Enterobacteriaceae, is about to be lost in our country. The emergence of new resistance mechanisms to carbapenems in these Enterobacteriaceae exposes patients to a risk of treatment failure without any other therapeutic options. This dramatic situation is paradoxical because we are well aware of the 2 major factors responsible for this situation: 1) MDRO cross-transmission, associated with a low compliance to standard precautions, especially hand hygiene, and 2) overexposure of patients to antibiotics. The implementation of a "search and isolate" policy, which was justified to control the spread of some MDRO that remained rare in the country, was not associated with a better adherence to standard precautions. The antibiotic policy and the measures implemented to control antibiotic consumptions have rarely been enforced and have shown inconsistent results. Notably, no significant decrease of antibiotic consumption has been observed. There is no excuse for these poor results, because some authors evaluating the effectiveness of programs for the control of MDRO have reported their positive effects on antimicrobial resistance without any detrimental effects. It is now urgent to deal with the 2 major factors by establishing an educational and persuasive program with quantified and opposable objectives. Firstly, we have to improve the observance of hand hygiene above 70%. Secondly, we have to define and reach a target for the reduction of antibiotic consumption both in community and in hospital settings. PMID:25169940

Zahar, J-R; Lesprit, P

2014-09-01

267

Herbal modulation of P-glycoprotein.  

Science.gov (United States)

P-glycoprotein (Pgp) is a 170 kDa phosphorylated glycoprotein encoded by human MDR1 gene. It is responsible for the systemic disposition of numerous structurally and pharmacologically unrelated lipophilic and amphipathic drugs, carcinogens, toxins, and other xenobiotics in many organs, such as the intestine, liver, kidney, and brain. Like cytochrome P450s (CYP3A4), Pgp is vulnerable to inhibition, activation, or induction by herbal constituents. This was demonstrated by using an ATPase assay, purified Pgp protein or intact Pgp-expressing cells, and proper probe substrates and inhibitors. Curcumin, ginsenosides, piperine, some catechins from green tea, and silymarin from milk thistle were found to be inhibitors of Pgp, while some catechins from green tea increased Pgp-mediated drug transport by heterotropic allosteric mechanism, and St. John's wort induced the intestinal expression of Pgp in vitro and in vivo. Some components (e.g., bergamottin and quercetin) from grapefruit juice were reported to modulate Pgp activity. Many of these herbal constituents, in particular flavonoids, were reported to modulate Pgp by directly interacting with the vicinal ATP-binding site, the steroid-binding site, or the substrate-binding site. Some herbal constituents (e.g., hyperforin and kava) were shown to activate pregnane X receptor, an orphan nuclear receptor acting as a key regulator of MDR1 and many other genes. The inhibition of Pgp by herbal constituents may provide a novel approach for reversing multidrug resistance in tumor cells, whereas the stimulation of Pgp expression or activity has implication for chemoprotective enhancement by herbal medicines. Certain natural flavonols (e.g., kaempferol, quercetin, and galangin) are potent stimulators of the Pgp-mediated efflux of 7,12-dimethylbenz(a)-anthracene (a carcinogen). The modulation of Pgp activity and expression by these herb constituents may result in altered absorption and bioavailability of drugs that are Pgp substrates. This is exemplified by increased oral bioavailability of phenytoin and rifampin by piperine and decreased bioavailability of indinavir, tacrolimus, cyclosporine, digoxin, and fexofenadine by coadministered St. John's wort. However, many of these drugs are also substrates of CYP3A4. Thus, the modulation of intestinal Pgp and CYP3A4 represents an important mechanism for many clinically important herb-drug interactions. Further studies are needed to explore the relative role of Pgp and CYP3A4 modulation by herbs and the mechanism for the interplay of these two important proteins in herb-drug interactions. PMID:15072439

Zhou, Shufeng; Lim, Lee Yong; Chowbay, Balram

2004-02-01

268

Drug resistance pattern in multidrug resistance pulmonary tuberculosis patients  

International Nuclear Information System (INIS)

To evaluate the frequency of drug resistance profiles of multidrug resistant tuberculosis (MDR-TB) isolates of pulmonary tuberculosis patients, against both the first and the second line drugs. Study Design: An observational study. Place and Duration of Study: The multidrug resistant tuberculosis (MDR-TB) ward of Ojha Institute of Chest Diseases (OICD), Karachi, from 1996 to 2006. Methodology: Culture proven MDR-TB cases (resistant to both isoniazid and Rifampicin) were retrospectively reviewed. Susceptibility testing was performed at the clinical laboratory of the Aga Khan University. Sensitivity against both first and second line anti-tuberculosis drugs was done. Susceptibility testing was performed using Agar proportion method on enriched middle brook 7H10 medium (BBL) for Rifampicin, Isoniazid, Streptomycin, Ethambutol, Ethionamide, Capreomycin and Ciprofloxacin. Pyrazinamide sensitivity was carried out using the BACTEC 7H12 medium. During the study period MTB H37Rv was used as control. Results: Out of total 577 patients, all were resistant to both Rifampicin and Isoniazid (INH). 56.5% isolates were resistant to all five first line drugs. Resistances against other first line drugs was 76.60% for Pyrazinamide, 73% for Ethambutol and 68.11% for Streptomycin. Five hundred and ten (88%) cases were MDR plus resistant to one more first line drug. Forty (07%) isolates were MDR plus Quinolone-resistant. They were sensitive to Capreomycin but sensitivity against Amikacin aeomycin but sensitivity against Amikacin and Kanamycin were not tested. Conclusion: There were high resistance rates in MDR-TB to remaining first line and second line drugs. Continuous monitoring of drug resistance pattern especially of MDR isolates and treatment in specialized centers is a crucial need for future TB control in Pakistan. (author)

269

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

270

Establishment of a human hepatoma multidrug resistant cell line in vitro  

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Full Text Available AIM: To establish a multidrug-resistant hepatoma cell line (SK-Hep-1, and to investigate its biological characteristics.METHODS: A highly invasive SK-Hep-1 cell line of human hepatocellular carcinoma, also known as malignant hepatoma was incubated with a high concentration of cisplatin (CDDP to establish a CDDP-resistant cell subline (SK-Hep-1/CDDP. The 50% inhibitory dose (IC50 values and the resistance indexes [(IC50 SK-Hep-1/CDDP/(IC50 SK-Hep-1] for other chemotherapeutic agents and the growth curve of cells were all evaluated using cell counting kit-8 assays. The distribution of the cell cycles were detected by flow cytometry. Expression of acquired multidrug resistance P-glycoprotein (MDR1, ABCB1 and multidrug resistance-associated protein 1 (MRP1, ABCC1 was compared with that in parent cells by Western blotting and immunofluorescence combined with laser scanning confocal microscopy.RESULTS: The SK-Hep-1/CDDP cells (IC50 = 70.61 ± 1.06 ?g/mL was 13.76 times more resistant to CDDP than the SK-Hep-1 cells (IC50 = 5.13 ± 0.09 ?g/mL, and CDDP-resistant cells also demonstrated cross-resistance to many anti-tumor agents such as doxorubicin, 5-fluorouracil and vincristine. Similar morphologies were determined in both SK-Hep-1 and SK-Hep-1/CDDP groups. The cell cycle distribution of the SK-Hep-1/CDDP cell line exhibited a significantly increased percentage of cells in S (42.2% ± 2.65% vs 27.91% ± 2.16%, P < 0.01 and G2/M (20.67% ± 5.69% vs 12.14% ± 3.36%, P < 0.01 phases in comparison with SK-Hep-1 cells, while the percentage of cells in the G0/G1 phase decreased (37.5% ± 5.05% vs 59.83% ± 3.28%, P < 0.01. The levels of MDR1 and MRP1 were overexpressed in the SK-Hep-1/CDDP cells exhibiting the MDR phenotype.CONCLUSION: Multiple drug resistance of multiple drugs in the human hepatoma cell line SK-Hep-1/CDDP was closely related to the overexpression of MDR1 and MRP1.

Yuan Zhou, Xian-Long Ling, Shi-Wei Li, Xin-Qiang Li, Bin Yan

2010-05-01

271

Establishment of a Multidrug Resistance Cell Line A549/cDDP of Human Lung Adenocarcinoma and Expression Analysis of Multidrug Resistance-Associated Genes  

OpenAIRE

Background and objective It has been proven that chemotherapy failure caused by multidrug resistance in lung tumor cells is the main cause for the patient's survival rate. The aim of this study is to establish a multidrug resistance cell line of human lung adenocarcinoma and study the mechanism of multidrug resistance. Methods Human lung adenocarcinoma cell line A549 was induced to multidrug resistance cell line A549/cDDP by intermittentadministration of high dose of cisplatin (cDDP). The mul...

Pan, Yongcheng; Zhao, Weigang; Wang, Jianjun; Liu, Quan; Yang, Guanghai; Li, Jinsong

2009-01-01

272

The Connection between the Toxicity of Anthracyclines and Their Ability to Modulate the P-Glycoprotein-Mediated Transport in A549, HepG2, and MCF-7 Cells  

OpenAIRE

Multidrug resistance (MDR) is a major obstacle to the successful chemotherapy of solid tumors. We compared the resistance of the most popular solid tumors, breast adenocarcinoma (MCF-7 cell line) and nonsmall cell lung (A549 cell line) hepatocellular liver carcinoma (HepG2 cells), to aclarubicin (ACL) and doxorubicin (DOX). This research aimed at determining the relation between the toxicity of ACL and DOX, their cell accumulation, and then effect on P-glycoprotein functionality. ACL is more ...

Aneta Rogalska; Marzena Szwed; Ej Rychlik, B. X. A. X. C.

2014-01-01

273

Characterization of a multidrug-resistant, novel bacteroides genomospecies.  

Science.gov (United States)

Metronidazole- and carbapenem-resistant Bacteroides fragilis are rare in the United States. We isolated a multidrug-resistant anaerobe from the bloodstream and intraabdominal abscesses of a patient who had traveled to India. Whole-genome sequencing identified the organism as a novel Bacteroides genomospecies. Physicians should be aware of the possibility for concomitant carbapenem- and metronidazole-resistant Bacteroides infections. PMID:25529016

Salipante, Stephen J; Kalapila, Aley; Pottinger, Paul S; Hoogestraat, Daniel R; Cummings, Lisa; Duchin, Jeffrey S; Sengupta, Dhruba J; Pergam, Steven A; Cookson, Brad T; Butler-Wu, Susan M

2015-01-01

274

Characterization of a Multidrug-Resistant, Novel Bacteroides Genomospecies  

Science.gov (United States)

Metronidazole- and carbapenem-resistant Bacteroides fragilis are rare in the United States. We isolated a multidrug-resistant anaerobe from the bloodstream and intraabdominal abscesses of a patient who had traveled to India. Whole-genome sequencing identified the organism as a novel Bacteroides genomospecies. Physicians should be aware of the possibility for concomitant carbapenem- and metronidazole-resistant Bacteroides infections. PMID:25529016

Salipante, Stephen J.; Kalapila, Aley; Pottinger, Paul S.; Hoogestraat, Daniel R.; Cummings, Lisa; Duchin, Jeffrey S.; Sengupta, Dhruba J.; Pergam, Steven A.; Cookson, Brad T.

2015-01-01

275

Chitosan-g-TPGS nanoparticles for anticancer drug delivery and overcoming multidrug resistance.  

Science.gov (United States)

To overcome the P-glycoprotein (P-gp)-induced multidrug resistance (MDR) of cancer cells, a novel copolymer, chitosan-graft-D-?-tocopheryl polyethylene glycol 1000 (TPGS) (CT) was synthesized for doxorubicin (DOX) delivery by the P-gp inhibiting virtue of TPGS. DOX-loaded CT nanoparticles (NPs) were fabricated by a modified solvent extraction/evaporation method combined with ionic cross-linking to form a uniform particle size of 140-180 nm with ?40% DOX loading efficiency. These drug-loaded CT NPs demonstrated a pH-responsive release behavior, and DOX was released more quickly under low pH values. Significant cell cytotoxicity was observed on the human hepatocarcinoma cells (HepG2 and BEL-7402) and human breast adenocarcinoma cells (MCF-7). The cell cytotoxicity and apoptosis of drug-resistant cells (MCF-7/DOX and BEL-7402/5-Fu), was greatly enhanced as compared to Adriamycin. The IC50 value showed that DOX-loaded CT NPs could be 1.5-199-fold more effective than Adriamycin. This can be attributed to the P-gp blocking and down-regulation of ATP levels by the CT NPs. The potential of these NPs to act as an oral delivery system was also investigated. Both the pharmacokinetic properties and in vivo antitumor activity of DOX-loaded CT NPs were improved compared with Adriamycin. PMID:24229050

Guo, Yuanyuan; Chu, Min; Tan, Songwei; Zhao, Shuang; Liu, Hanxiao; Otieno, Ben Oketch; Yang, Xiangliang; Xu, Chuanrui; Zhang, Zhiping

2014-01-01

276

Combination of tunicamycin with anticancer drugs synergistically enhances their toxicity in multidrug-resistant human ovarian cystadenocarcinoma cells  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background The pharmacologic modulatory effects of the antibiotic, tunicamycin (TM, on multidrug-resistant human UWOV2 ovarian cancer cells are reported. The UWOV2 cell line was derived from a cystadenocarcinoma in a patient refractory to combination chemotherapy with actinomycin D, vincristine (VCR, cis-diaminedichloroplatinum (II (CDDP and doxorubicin (DXR. In an attempt to explain drug resistance in this cell line, we examined the effects of TM on their sensitivity to various anticancer drugs, the uptake, efflux and retention of [3H]VCR, and their ability to bind [14C]DXR and [3H]azidopine (AZD, a photoaffinity label of the multidrug transporter, P-glycoprotein (Pgp. Results TM effectively decreased the EC50 for DXR, EXR, VCR and CDDP, thus enhancing their cytotoxicity. The antibiotic also prolonged the intracellular retention time of [3H]VCR and increased the binding of both [14C]DXR and [3H]AZD to the cells. Conclusion It is concluded that the pharmacomodulatory effects of TM in these cells are mediated by global inhibition of protein and glycoprotein synthesis and synergistic interaction with antineoplastic drugs. The ability of TM to enhance the sensitivity of drug resistant tumour cells may have impact on the design and optimization of novel resistance modifiers to improve the efficacy of combination treatment of intractable neoplasms.

Gabriels Gary A

2007-04-01

277

Phytochemical analysis and cytotoxicity towards multidrug-resistant leukemia cells of essential oils derived from Lebanese medicinal plants.  

Science.gov (United States)

Juniperus excelsa fruit essential oil as well as J. oxycedrus, Cedrus libani, and Pinus pinea wood essential oils have been obtained with yields between 2.2?±?0.3?% to 3.4?±?0.5?% and analyzed by gas chromatography. Sesquiterpenes mainly characterized C. libani and J. oxycedrus essential oils, while in P. pinea and J. excelsa, monoterpenes were the most abundant compounds. In J. oxycedrus, cis-calamenene (7.8?%), cuparene (3.8?%), and cis-thujopsenal (2.0?%) have been detected for the first time. The cytotoxic activity of these essential oils against drug-sensitive CCRF-CEM and multidrug-resistant P-glycoprotein-expressing CEM/ADR5000 leukemia cells has been investigated (IC?? values: 29.46 to 61.54?µg/mL). Remarkably, multidrug-resistant CEM/ADR5000 cells did not reveal cross-resistance, indicating that these essential oils might be useful to treat otherwise drug-resistant and refractory tumors. PMID:23154840

Saab, Antoine M; Guerrini, Alessandra; Sacchetti, Gianni; Maietti, Silvia; Zeino, Ma?en; Arend, Joachim; Gambari, Roberto; Bernardi, Francesco; Efferth, Thomas

2012-12-01

278

Disposition of Cremophor EL in humans limits the potential for modulation of the multidrug resistance phenotype in vivo.  

Science.gov (United States)

The purpose of the present study was to characterize the distribution and elimination kinetics of the paclitaxel vehicle Cremophor EL (CrEL), a polyoxyethylated castor oil that can modulate P-glycoprotein-mediated multidrug resistance in vitro. The pharmacokinetics of CrEL were studied using noncompartmental models in 23 patients with histological proof of malignant solid tumors, receiving paclitaxel as a 3-h i.v. infusion at dose levels ranging from 100-225 mg/m2 (corresponding to CrEL doses of 8.33-18.8 ml/m2). Serial plasma samples were obtained before and up to 72 h after drug administration, and were analyzed for the presence of CrEL by a novel colorimetric dye-binding microassay. The area under the plasma concentration versus time curves and the peak plasma levels of CrEL increased from 253+/-36.8 (mean+/-SD) to 680+/- 180 microl.h/ml, and from 3.40+/-0.10 to 6.58+/-0.52 microl/ml, respectively, consistent with linear pharmacokinetics. Disappearance of CrEL from the central plasma compartment was characterized by a terminal elimination half-life of 84.1+/-20.4 h, resulting in extended persistence of substantial levels even at 1 week after paclitaxel treatment. The observed volume of distribution was extremely low and averaged 3.70+/-0.49 liters/m2, implying that the tumor delivery of CrEL is insignificant. Our results indicate that CrEL is a relatively slow clearance compound and that its distribution is limited to the central plasma compartment. Hence, CrEL is not likely to play a role in reversing P-glycoprotein-mediated multidrug resistance to paclitaxel in vivo. PMID:9717822

Sparreboom, A; Verweij, J; van der Burg, M E; Loos, W J; Brouwer, E; Viganò, L; Locatelli, A; de Vos, A I; Nooter, K; Stoter, G; Gianni, L

1998-08-01

279

The Heterogeneous Evolution of Multidrug-Resistant Mycobacterium tuberculosis  

OpenAIRE

Recent surveillance data of multidrug-resistant tuberculosis (MDR-TB) reported the highest rates of resistance ever documented. As further amplification of resistance in MDR strains of Mycobacterium tuberculosis occurs, extensively drug-resistant (XDR) and totally drug resistant (TDR) TB are beginning to emerge. Whilst for the most part, the epidemiological factors involved in the spread of MDR-TB are understood, insights into the bacterial drivers of MDR-TB have been gained only recently, la...

Mu?ller, Borna; Borrell, Sonia; Rose, Graham; Gagneux, Sebastien

2012-01-01

280

The multidrug-resistance transporter ABCB5 is expressed in human placenta.  

Science.gov (United States)

ATP-binding cassette (ABC) transporters in placenta protectively transport drugs and xenobiotics. ABCB5 [subfamily B (MDR/TAP)] is a novel ABC multidrug-resistance transporter that also mediates cell fusion, stem cell function, and vasculogenic plasticity. Immunohistochemistry and double-labeling immunofluorescence staining for ABCB5 and ABCB5/CD200, respectively, was performed on formalin-fixed, paraffin-embedded placental tissue from 5 first trimester, 5 second trimester, and 5 term pregnancies as well as 5 partial moles, and 5 complete moles. In addition, tumor cells from 5 choriocarcinoma and 5 placental site trophoblastic tumor cases were examined. ABCB5 staining was observed in villous trophoblasts in 100% (5/5) of first trimester placentas (with progressive decrease in term placentas); 100% of partial moles (5/5); and 100% of complete moles (5/5). Notably, reactivity was discretely restricted to the inner trophoblast layer, with no staining of overlying syncytiotrophoblast. Antibody specificity and localization was confirmed further by in situ hybridization. ABCB5 expression was retained in 20% of choriocarcinomas (1/5) and 40% of placental site trophoblastic tumors (2/5). Prior studies have localized expression of multidrug-resistance-1, also known as ABCB1, within the syncytiotrophoblast of early placentas, where it serves a protective function as an efflux transporter. Our results show that ABCB5 is preferentially expressed in the cytotrophoblast layer of placental villi. The expression of this novel biomarker at the maternal-fetal interface raises questions on its role in placental structure and function as well as on its potential contribution to the protective efflux provided by other P-glycoprotein transporters. PMID:24300535

Volpicelli, Elgida R; Lezcano, Cecilia; Zhan, Qian; Girouard, Sasha D; Kindelberger, David W; Frank, Markus H; Frank, Natasha Y; Crum, Christopher P; Murphy, George F

2014-01-01

281

Using 99Tcm-MIBI to evaluate tumor multidrug resistance and monitor the reversing of chemosensitizer  

International Nuclear Information System (INIS)

Objective: To study the correlation between uptake of 99Tcm-methoxyisobutylisonitrile (MIBI) and multidrug-resistant P-glycoprotein (gp), and to evaluate the effect of chemosensitizer. Methods: Tumor bearing mice model was established by implanting human cancer cell line MCF-7/Adr, the model mice were randomized into two groups: chemosensitizer verapamil group and control group. Before and after giving verapamil, 99Tcm-MIBI imaging was performed at 15, 60, 90, 120 min, respectively. Mice of the control group were sacrificed after the pre-verapamil imaging, and mice of the verapamil group were sacrificed after the post-verapamil imaging to get %ID/g of tumor and major organs. The level of P-gp was measured with immunocytochemical assay and mRNA of mdr1 gene determined with RT-PCR was obtained simultaneously. Results: After giving verapamil the TPN ratio of tumor increased significantly except on 120 min imaging. 99Tcm-MIBI uptake difference between the verapamil group and control group was obvious (P=0.045, 0.015, 0.042, respectively). The expression of mdr1 mRNA decreased significantly after verapamil reversing (t=4.873, P=0.008). The level of P-gp declined from 0.1038 ± 0.0078 to 0.0096 ± 0.0059 (t=3.579, P=0.023). The 99Tcm-MIBI uptake of tumor, liver and kidney rose obviously after reversing, %ID/g increments were 106.83%, 40.35%, 166.07%, respectively whereas it was slightly %, respectively whereas it was slightly declined, -12.82%, in heart. Conclusion: 99Tcm-MIBI imaging may evaluate multidrug resistance (MDR) mediated by P-gp and be used to monitor the reversing effect of chemosensitizer in P-gp positive tumors

282

Design real-time reversal of tumor multidrug resistance cleverly with shortened carbon nanotubes  

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Multidrug resistance (MDR) in tumors renders many currently available chemotherapeutic drugs ineffective. Research in nanobiotechnology-based therapeutic alternatives has provided innovative and promising strategies to overcome MDR. The aim of this study was to investigate whether the new strategy of a co-loaded reversal agent and chemotherapeutic drug with shortened carbon nanotubes (CNTs) would show useful effects on the real-time reversal of tumor MDR. CNTs were cut and purified via ultrasonication and oxidative acid treatment to optimize their length for drug-delivery vehicles, then verapamil (Ver) and doxorubicin (Dox) were co-loaded on shortened CNTs (denoted as Ver/Dox/shortened CNTs), which acted as a drug delivery system. The multidrug resistant leukemia K562/A02 cells were treated with the denoted Ver/Dox/shortened CNTs. The real-time reversal of tumor MDR were evaluated by flow cytometer, 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, acridine orange/ethidium bromide staining, and Western blot analysis. In the same MDR tumor cells the new strategy of a co-loaded reversal agent and chemotherapeutic drug with CNTs could inhibit the function of P-glycoprotein in real-time by Ver as reversal agent, significantly increase the uptake of Dox, enhance the sensitivity of the MDR cancer cells to the chemotherapeutic agent, and induce apoptosis. It was therefore concluded that a co-loaded reversal agent and chemotherapeutic drug with shortened CNTs could have real-time reversal ability of MDR in tumors, which could represent a promising approach in cancer therapy. PMID:25525333

Wu, Pingping; Li, Shang; Zhang, Haijun

2014-01-01

283

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

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The aim of the present study was to evaluate the association between DNA methylation and multidrug resistance (MDR) in glioma and identify novel effectors responsible for MDR in human gliomas. An MDR glioma cell line, SGH-44/ADM, was developed using adriamycin (ADM) impulse treatment. Cryopreservation, recovery and withdrawal were performed to evaluate the stability of SGH-44/ADM cells. The adherence rate and cellular morphology were observed by microscopy, and the cell growth curve and doubling time were determined. DNA methylation was analyzed using a methylated DNA immunoprecipitation microarray chip (MeDIP-Chip). The cell cycle, Rh123 ingestion and exudation, and SGH-44/ADM apoptosis were analyzed by flow cytometry. SGH-44/ADM cells showed little difference as compared with parental cells, except that SGH-44/ADM cells were bigger in size with a wizened nucleus. Compared to SGH-44 cells, a larger proportion of SGH-44/ADM cells remained in G1 and S phase, as measured by flow cytometry. The MDR of SGH-44/ADM was associated with the upregulation of multi-drug resistance 1, prostaglandin-endoperoxide synthase 2 (COX-2); protein kinase C ? (PKC?); however, the expression of these genes was not associated with DNA methylation. In the MeDIP-Chip analysis, 74 functions were markedly enhanced, and seven significant pathways were observed. Genes including SNAP47, ARRB2, PARD6B, TGFB1, VPS4B and CBLB were identified by gene ontology analysis. The predominant molecular mechanism of MDR in SGH-44/ADM cells was identified as exocytosis and efflux. The expression of COX-2, PKC? and P-glycoprotein (Pgp) was not found to be associated with DNA methylation. Genes including SNAP47, VAMP4 and VAMP3 may serve as the downstream effectors of Pgp, COX-2 or PKC?; however, further experiments are required to verify these observations. PMID:25333456

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

2015-01-01

284

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

285

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

286

Antitumor activity of new liposomal prodrug of mitomycin C in multidrug resistant solid tumor: insights of the mechanism of action.  

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The antitumor activity of a novel thiolytically cleavable lipid-based prodrug of mitomycin C (MMC) delivered by STEALTH liposomes (SL) was studied in drug resistant human ovarian carcinoma A2780/AD model and compared with free MMC and both free and SL forms of an established anticancer drug--doxorubicin (DOX). It was found that SL-prodrug (SL-pMMC) possessed enhanced antitumor activity when compared with the parent MMC, free DOX, and SL-DOX. An observance of the high antitumor efficiency of SL-pMMC was a result of its preferential accumulation in the tumor by the enhanced permeability and retention (EPR) effect, suppression of multidrug resistance (MDR) associated with P-glycoprotein and MRP drug efflux pumps, activation of caspase-dependent apoptosis signaling pathways and suppression of antiapoptotic cellular defense by increasing the BAX/BCL2 ratio. Consequently, the described SL-pMMC formulations can be considered good candidates for the chemotherapy of multidrug resistant tumors. PMID:17671898

Zalipsky, Samuel; Saad, Maha; Kiwan, Radwan; Ber, Elizabeth; Yu, Ning; Minko, Tamara

2007-01-01

287

Sinomenine Sensitizes Multidrug-Resistant Colon Cancer Cells (Caco-2) to Doxorubicin by Downregulation of MDR-1 Expression  

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Chemoresistance in multidrug-resistant (MDR) cells over expressing P-glycoprotein (P-gp) encoded by the MDR1 gene, is a major obstacle to successful chemotherapy for colorectal cancer. Previous studies have indicated that sinomenine can enhance the absorption of various P-gp substrates. In the present study, we investigated the effect of sinomenine on the chemoresistance in colon cancer cells and explored the underlying mechanism. We developed multidrug-resistant Caco-2 (MDR-Caco-2) cells by exposure of Caco-2 cells to increasing concentrations of doxorubicin. We identified overexpression of COX-2 and MDR-1 genes as well as activation of the NF-?B signal pathway in MDR-Caco-2 cells. Importantly, we found that sinomenine enhances the sensitivity of MDR-Caco-2 cells towards doxorubicin by downregulating MDR-1 and COX-2 expression through inhibition of the NF-?B signaling pathway. These findings provide a new potential strategy for the reversal of P-gp-mediated anticancer drug resistance. PMID:24901713

Liu, Zhen; Duan, Zhi-Jun; Chang, Jiu-Yang; Zhang, Zhi-feng; Chu, Rui; Li, Yu-Ling; Dai, Ke-Hang; Mo, Guang-quan; Chang, Qing-Yong

2014-01-01

288

Effect of phenoxazine MDR modulators on photoaffinity labeling of P-glycoprotein by [3H] azidopine: an approach to understand drug resistance in cancer chemotherapy  

International Nuclear Information System (INIS)

P-glycoprotein (P-gp) rich membrane fractions from KB-VI cells were isolated and the interaction of [3H] azidopine with membrane fractions in the presence of 25, 50 and 100 ?M concentration of each of the twenty N10 -substituted phenoxazines, was under taken and the extent of competition was compared to a standard modulator, verapamil. Competition data showed that only two modulators 4 and 6 exhibited the maximum competition (>50%). Among the compounds examined, three of them interact strongly (>50%), six marginally (<45%) and remaining failed to interact with P-gp, indicating that there may be multiple mechanisms for MDR. (author)

289

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

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Killifish survive and reproduce in the New Bedford Harbor (NBH) in Massachusetts (MA), USA, a site severely contaminated with polychlorinated biphenyls (PCBs) for decades. Levels of 22 different PCB congeners were analyzed in liver from killifish collected in 2008. Concentrations of dioxin-like PCBs in liver of NBH killifish were ?400 times higher, and the levels of non-dioxin-like PCBs ?3000 times higher than in killifish from a reference site, Scorton Creek (SC), MA. The NBH killifish are known to be resistant to the toxicity of dioxin-like compounds and to have a reduced aryl hydrocarbon receptor (AhR) signaling response. Little is known about the responses of these fish to non-dioxin-like PCBs, which are at extraordinarily high levels in NBH fish. In mammals, some non-dioxin-like PCB congeners act through nuclear receptor 1I2, the pregnane-X-receptor (PXR). To explore this pathway in killifish, a PXR cDNA was sequenced and its molecular phylogenetic relationship to other vertebrate PXRs was determined. Killifish were also collected in 2009 from NBH and SC, and after four months in the laboratory they were injected with a single dose of either the dioxin-like PCB 126 (an AhR agonist) or the non-dioxin-like PCB 153 (a mammalian PXR agonist). Gills and liver were sampled three days after injection and transcript levels of genes encoding PXR, cytochrome P450 3A (CYP3A), P-glycoprotein (Pgp), AhR2 and cytochrome P450 1A (CYP1A) were measured by quantitative PCR. As expected, there was little effect of PCB exposure on mRNA expression of AhR2 or CYP1A in liver and gills of NBH fish. In NBH fish, but not in SC fish, there was increased mRNA expression of hepatic PXR, CYP3A and Pgp upon exposure to either of the two PCB congeners. However, basal PXR and Pgp mRNA levels in liver of NBH fish were significantly lower than in SC fish. A different pattern was seen in gills, where there were no differences in basal mRNA expression of these genes between the two populations. In SC fish, but not in NBH fish, there was increased mRNA expression of branchial PXR and CYP3A upon exposure to PCB126 and of CYP3A upon exposure to PCB153. The results suggest a difference between the two populations in non-AhR transcription factor signaling in liver and gills, and that this could involve killifish PXR. It also implies possible cross-regulatory interactions between that factor (presumably PXR) and AhR2 in liver of these fish. PMID:25553538

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

2015-02-01

290

Expression of members of the multidrug resistance protein family in human term placenta.  

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The placenta serves, in part, as a barrier to exclude noxious substances from the fetus. In humans, a single-layered syncytium of polarized trophoblast cells and the fetal capillary endothelium separate the maternal and fetal circulations. P-glycoprotein is present in the syncytiotrophoblast throughout gestation, consistent with a protective role that limits exposure of the fetus to hydrophobic and cationic xenobiotics. We have examined whether members of the multidrug resistance protein (MRP) family are expressed in term placenta. After screening a placenta cDNA library, partial clones of MRP1, MRP2, and MRP3 were identified. Immunofluorescence and immunoblotting studies demonstrated that MRP2 was localized to the apical syncytiotrophoblast membrane. MRP1 and MRP3 were predominantly expressed in blood vessel endothelia with some evidence for expression in the apical syncytiotrophoblast. ATP-dependent transport of the anionic substrates dinitrophenyl-glutathione and estradiol-17-beta-glucuronide was also demonstrated in apical syncytiotrophoblast membranes. Given the cellular distribution of these transporters, we hypothesize that MRP isoforms serve to protect fetal blood from entry of organic anions and to promote the excretion of glutathione/glucuronide metabolites in the maternal circulation. PMID:11004020

St-Pierre, M V; Serrano, M A; Macias, R I; Dubs, U; Hoechli, M; Lauper, U; Meier, P J; Marin, J J

2000-10-01

291

Cationic submicron emulsions overcome multidrug resistance in SGC7901/VCR cells.  

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The over-expression of P-glycoprotein (P-gp) is associated with the development of multi-drug resistance (MDR) in cancer cells. In this study, we examined whether cationic submicron emulsions (CSEs) can efficiently deliver hydroxycamptothecin (HCPT) into MDR cells (SGC7901/VCR cells) via electrostatic-mediated endocytosis, thus overcoming MDR. We prepared HCPT-CSEs and rhodamine-123-CSEs (RH-123-CSEs), and examined the in vitro cytotoxic activity of HCPT-CSEs and the intracellular accumulation of HCPT and RH-123 in SGC7901/VCR cells. The HCPT-CSEs significantly increased the intracellular accumulation of HCPT (8.2-fold higher than HCPT-injection) and enhanced cytotoxic activity of HCPT (2.7-fold higher than HCPT-injection with verapamil). The fluorescence microscopic and flow cytometric detection on RH-123 supported the intracellular accumulation effect of CSEs. These results indicate CSEs may enhance drug-CSEs internalization followed by releasing their contents into the cytoplasm (near nuclear), thus lowering P-gp-mediated drug efflux. Furthermore, these in vitro results suggest that CSEs are a potentially useful drug delivery system to circumvent P-gp-mediated MDR of tumor cells. PMID:21434576

Zhao, Yong-Xing; Liang, Wen-Quan; Wang, Ye; Liu, Dan-Xing

2011-02-01

292

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

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The P-glycoprotein, encoded by the multidrug resistance (MDR)1 gene, extrudes fat-soluble compounds to the extracellular environment. However, the DNA damage of pesticides in subjects with genetic variation in MDR1 has not been investigated. In this study, the comet assay was applied to examine the extent of DNA damage in the peripheral blood of 195 fruit growers who had been exposed to pesticides and 141 unexposed controls. The MDR1 polymorphisms were identified. Questionnaires were administered to obtain demographic data and occupational history. Results showed subjects experiencing high (2.14??m/cell, P tail moment than controls (1.28??m/cell). Compared to the MDR1 T-129C (rs3213619) TC/CC carriers, the TT carriers had increased DNA tail moment in controls (1.30 versus 1.12??m/cell, P < 0.01). Similar results were observed in the high and low pesticide-exposed groups. Combined analysis revealed that pesticide-exposed fruit growers with MDR1 -129 TT genotype had the greatest DNA damage in the subjects with the combinations of pesticide exposure and MDR1 -129 genotypes. In conclusion, pesticide exposed individuals with susceptible MDR1 -129 genotypes may experience increased risk of DNA damage. PMID:24791009

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

2014-01-01

293

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

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Full Text Available 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 total of 130 paraffin embedded tissue samples collected from HL patients were analyzed to identify the C3435T polymorphism. As a control group, 120 healthy subjects were enrolled in the study. The C3435T Polymorphism was genotyped by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP method. Data analysis was carried out using the statistical package SPSS version 17 to compute all descriptive statistics. Chi-square and Fisher exact tests were used to evaluate the genotype distribution and allele frequencies of the studied polymorphism. Results these studies revealed that the frequency of T allele was significantly higher in HL patients compared to the controls (P 0.05. Conclusions these results suggest that MDR1 C3435T polymorphism might play a role in HL occurrence; however this polymorphism is not correlated with the clinical response to ABVD.

Haddadin William J

2011-07-01

294

Study of the mechanisms underlying the reversal of multidrug resistance of human neuroblastoma multidrug-resistant cell line SK-N-SH/MDR1 by low-intensity pulsed ultrasound.  

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The aim of the present study was to investigate the underlying mechanism(s) involved in reversing multidrug resistance (MDR) of SK-N-SH/MDR1 by low-intensity pulsed ultrasound (LIPUS). Membrane alteration of SK-N-SH/MDR1 cells exposed to LIPUS was analyzed by scanning electron microscopy (SEM). Immunofluorescence and western blotting were used\\ to detect changes in the expression of the MDR-related proteins P-glycoprotein (P-gp), multidrug resistance protein 1 (MRP1) and glutathione-s-transferase-? (GST-?) after the optimum ultrasonic. The optimum ultrasonic conditions were 0.3 MHz, 1.0 W/cm², 40 sec and the chemosensitivity of SK-N-SH/MDR1 cells was significantly increased (P0.05). We demonstrated that LIPUS effectively reverses the MDR of SK-N-SH/MDR1, presumably via augmenting membrane permeability and decreasing the P-gp expression of SK-N-SH/MDR1. PMID:23483136

Sun, Yanhui; Li, Qin; Xu, Youhua; Pu, Conglun; Zhao, Lihua; Guo, Zhenhua; Ding, Xionghui; Jin, Xianqing

2013-05-01

295

Effect of magnetic nanoparticles of Fe3O4 and wogonin on the reversal of multidrug resistance in K562/A02 cell line  

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Full Text Available Jian Cheng,1,* Lin Cheng,1,* Baoan Chen,1,2 Guohua Xia,1 Chong Gao,1 Huihui Song,1 Wen Bao,1 Qinglong Guo,3 Haiwei Zhang,3 Xuemei Wang41Department of Hematology, Key Medical Disciplines of Jiangsu Province, Zhongda Hospital, Medical School of Southeast University, 2Department of Oncology of Southeast University, 3Key Laboratory of Carcinogenesis and Intervention of Jiangsu Province, China Pharmaceutical University, 4State Key Laboratory of Bioelectronics, Southeast University, Nanjing, People's Republic of China *These authors contributed equally to this workBackground: Multidrug resistance is the main obstacle to the efficiency of systemic chemotherapy against hematologic malignancy. This study investigated the reversible effect of the copolymer wogonin and daunorubicin coloaded into Fe3O4 magnetic anoparticles, and the mechanism potentially involved.Methods: The growth inhibition rate of K562/A02 cells was investigated by MTT assay, and apoptosis of cells and the intracellular daunorubicin concentration were detected by flow cytometry. Distribution of nanoparticles taken up by K562/A02 cells was observed under a transmission electron microscope and demonstrated by Prussian blue staining. The transcription level of MDR1 mRNA and expression of P-glycoprotein were determined by reverse transcriptase polymerase chain reaction and Western blotting assay, respectively.Results: The reversible effect of daunorubicin-wogonin magnetic nanoparticles was 8.87-fold that of daunorubicin + wogonin and of daunorubicin magnetic nanoparticles. Transmission electron microscopy and Prussian blue staining revealed that the nanoparticles were located in the endosome vesicles of cytoplasm. Also, the apoptosis rate and accumulation of intracellular daunorubicin in the daunorubicin-wogonin magnetic nanoparticle group were significantly higher than that in the daunorubicin, daunorubicin + wogonin, and daunorubicin magnetic nanoparticle groups. Furthermore, transcription of MDR1 mRNA and expression of P-glycoprotein in K562/A02 cells were significantly downregulated in the daunorubicin-wogonin magnetic nanoparticle group compared with the other groups.Conclusion: These findings suggest that the remarkable effects of the novel daunorubicin-wogonin magnetic nanoparticle formulation on multidrug resistant K562/A02 leukemia cells would be a promising strategy for overcoming multidrug resistance.Keywords: magnetic nanoparticles, Fe3O4, wogonin, multidrug resistance, daunorubicin, P-glycoprotein

Cheng J

2012-06-01

296

Noninvasive detection of multidrug resistance in patients with hematological malignancies: are we there yet?  

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The success of chemotherapy in the treatment of malignancies may be limited by cellular mechanisms leading to drug resistance. In hematological malignancies, mechanisms leading to the development of multidrug resistance (MDR) include overexpression of the membrane-based export pump P-glycoprotein (Pgp) and the MDR-associated protein (MRP). Recently, the overexpression of the lung-resistance protein (LRP) has also been associated with reduced intracellular drug accumulation. A major problem in assessing the significance of the expression of these resistance proteins in clinical MDR has been the variability of detection techniques either at the mRNA or protein level. Currently, the detection of resistance proteins relies heavily on antibody and cDNA probes, and these methods may not be informative about the in vivo function of Pgp, MRP, or LRP. Nuclear medicine imaging techniques such as single-photon emission tomography (SPECT) and positron emission tomography (PET) have been evaluated for noninvasive determination of the presence and the function of Pgp- and MRP-mediated transport systems. Technetium 99m ((99m)Tc)-sestamibi, an agent in clinical use for myocardial perfusion and tumor imaging, is recognized as a substrate for Pgp and MRP, and has been used to visualize Pgp expression. (99m)Tc-tetrofosmin is also a substrate for the Pgp efflux pump mechanism and is used to evaluate Pgp function in in vitro and in vivo studies. Recently, radiopharmaceuticals including carbon 11-labeled colchicine, verapamil, and daunorubicin have been used in cell line and animal studies for the evaluation of Pgp-mediated transport functions using PET technology. Preliminary results suggest that the potential to detect MDR in tumors prior to or after exposure to chemotherapeutic agents exists in imaging using either (99m)Tc-labeled compounds and SPECT or positron emitting compounds and PET. PMID:11970764

Kostakoglu, Lale

2002-03-01

297

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

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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

298

Expression of P-glycoprotein in adult T-cell leukemia cells  

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We have examined the expression of P-glycoprotein (P-gp) in adult T-cell leukemia (ATL) samples from 25 patients. Based on immunoblotting with a monoclonal antibody against P-gp, C219, 8 of 20 ATL patients were P-gp positive at the initial presentation. All 6 patients at the relapsed stage were P-gp positive, and refractory to chemotherapy. The expression of MDR1 mRNA in P-gp-positive ATL cells was increased at the relapsed stage of one patient. P-gp of this patient was photolabeled with (3H)azidopine and the labeling was inhibited with nimodipine, vinblastine and progesterone. These results suggest that P-gp expressed in ATL cells from patients at relapsed stage has the same binding site(s) for the drugs as that in multidrug resistant cells, and is correlated with the refractory nature of the cells to chemotherapy.

Kuwazuru, Y.; Hanada, S.; Furukawa, T.; Yoshimura, A.; Sumizawa, T.; Utsunomiya, A.; Ishibashi, K.; Saito, T.; Uozumi, K.; Maruyama, M. (Kagoshima Univ. (Japan))

1990-11-15

299

Expression of P-glycoprotein in adult T-cell leukemia cells  

International Nuclear Information System (INIS)

We have examined the expression of P-glycoprotein (P-gp) in adult T-cell leukemia (ATL) samples from 25 patients. Based on immunoblotting with a monoclonal antibody against P-gp, C219, 8 of 20 ATL patients were P-gp positive at the initial presentation. All 6 patients at the relapsed stage were P-gp positive, and refractory to chemotherapy. The expression of MDR1 mRNA in P-gp-positive ATL cells was increased at the relapsed stage of one patient. P-gp of this patient was photolabeled with [3H]azidopine and the labeling was inhibited with nimodipine, vinblastine and progesterone. These results suggest that P-gp expressed in ATL cells from patients at relapsed stage has the same binding site(s) for the drugs as that in multidrug resistant cells, and is correlated with the refractory nature of the cells to chemotherapy

300

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

301

Swelling-activated chloride channels in multidrug-sensitive and - resistant cells  

OpenAIRE

Resistance to chemotherapeutic agents in neoplastic cells is often mediated by expression of P-glycoprotein, which functions as a drug- efflux pump for a broad range of substrates. We have used a combination of patch clamp and video-imaging techniques to examine the expression and drug-efflux function of P-glycoprotein and to determine the possible correlation with swelling-activated chloride channels in drug- sensitive and -resistant cell lines. Two pairs of cell lines were used in these exp...

1994-01-01

302

Ecological aspects of the multidrug resistance to chemotherapy agents ????????????? ????????????? ???????????? ?????????? ?????? ? ???????????????????? ??????????. ????????????? ???????  

OpenAIRE

This paper presents generalized and analyzed literature data concerning the main mechanisms of the development of multidrug resistance (MDR) produced by tumour cells to chemotherapeutic agents. The conclusion is made about the biological role of acquired MDR phenotype for the tumour cell population.? ?????? ???????? ? ???????????????? ???????????? ??????, ?????????? ???????? ?????????? ???????? ?????...

Volkova Tatyana; Bagina Ulyana

2012-01-01

303

Ecological aspects of the multidrug resistance to chemotherapy agents ????????????? ????????????? ???????????? ?????????? ?????? ? ???????????????????? ??????????. ????????????? ???????  

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Full Text Available This paper presents generalized and analyzed literature data concerning the main mechanisms of the development of multidrug resistance (MDR produced by tumour cells to chemotherapeutic agents. The conclusion is made about the biological role of acquired MDR phenotype for the tumour cell population.? ?????? ???????? ? ???????????????? ???????????? ??????, ?????????? ???????? ?????????? ???????? ???????? ????????????? ????????????? ???????????? (??? ?????????? ?????? ? ???????????????????? ??????????. ??????? ?????????? ? ????????????? ???? ?????????????? ???????? ??? ??? ????????? ?????????? ?????? ? ?????.

Volkova Tatyana

2012-07-01

304

Pilot study on multidrug resistant tuberculosis in Nigeria  

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Full Text Available Background: Drug resistant tuberculosis (TB has lately emerged and it represents a serious public health problem. We set out to determine drug resistance among TB patients. Methods: Using automated BACTEC cultures, multidrug resistant-tuberculosis (MDR-TB was investigated in 117 diagnosed cases in Abuja, Nigeria. Results: Ten (31% of 32 culture-positive patients were resistant to at least one and four (13% to all of the four drugs tested. No association between drug resistance and human immunodeficiency virus (HIV infection was found. Conclusions: MDR-TB is present in Nigeria and larger studies are urgently required. TB clinical management and control efforts should be improved.

Lawson L

2010-09-01

305

Carotenoids reverse multidrug resistance in cancer cells by interfering with ABC-transporters.  

Science.gov (United States)

Proteins of the ATP-binding cassette superfamily, mainly P-glycoprotein (P-gp; MDR1), play an important role in the development of multidrug resistance (MDR) in cancer cells and thus in the potential failure of chemotherapy. A selection of carotenoids (?-carotene, crocin, retinoic acid, canthaxanthin, and fucoxanthin) was investigated whether they are substrates of P-gp, and if they can reverse MDR in resistant Caco-2 and CEM/ADR5000 cells as compared to the sensitive parent cell line CCRF-CEM. The activity of ABC transporter was determined in resistant and sensitive cells by spectrofluorometry and flow cytometry using the substrates doxorubicin, rhodamine 123, and calcein as fluorescent probes. The carotenoids increased accumulation of these P-gp substrates in a dose-dependent manner indicating that they themselves also function as substrates. Fucoxanthin and canthaxanthin (50-100 ?M) produced a 3-5-fold higher retention of the fluorescent probes than the known competitive inhibitor verapamil. Carotenoids showed a low cytotoxicity in cells with MDR with IC(50) values between 100 and 200 ?M. The combination of carotenoids with eight structurally different cytotoxic agents synergistically enhanced their cytotoxicity in Caco-2 cells, probably by inhibiting the function of the ABC transporters. For example, fucoxanthin synergistically enhanced the cytotoxicity of 5-FU 53.37-fold, of vinblastine 51.01-fold, and of etoposide 12.47-fold. RT-PCR was applied to evaluate the mRNA levels of P-gp in Caco-2 cells after treatment with carotenoids. Fucoxanthin and canthaxanthin significantly decreased P-gp levels to 12% and 24%, respectively as compared to untreated control levels (p<0.001). This study implies that carotenoids may be utilised as chemosensitisers, especially as adjuvants in chemotherapy. PMID:22770743

Eid, Safaa Yehia; El-Readi, Mahmoud Zaki; Wink, Michael

2012-08-15

306

Cytotoxic and multidrug resistance reversal activities of novel 1,4-dihydropyridines against human cancer cells.  

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Multidrug resistance (MDR) caused by P-glycoprotein (P-gp, ABCB1, MDR-1) transporter over-expression in cancer cells substantially limits the effectiveness of chemotherapy. 1,4-Dihydropyridines (DHPs) derivatives possess several pharmacological activities. In this study, 18 novel asymmetrical DHPs bearing 3-pyridyl methyl carboxylate and alkyl carboxylate moieties at C3 and C5 positions, respectively, as well as nitrophenyl or hetero aromatic rings at C4 were synthesized and tested for MDR reversal with the aim of establishing a structure-activity relationship (SAR) for these agents. Effect of these compounds on P-gp mediated MDR was assessed in P-gp over-expressing MES-SA/DX5 doxorubicin resistant cells by flow cytometric detection of rhodamine 123 efflux. MDR reversal was further examined as the alteration of doxorubicin?s IC50 in MES-SA/DX5 cells in the presence of DHPs by MTT assay and was compared to nonresistant MES-SA cells. Direct anticancer effect was examined against 4 human cancer cells including HL-60, K562, MCF-7 and LS180. Calcium channel blocking (CCB) activity was also measured as a potential side effect. Most DHPs, particularly compounds bearing 3-nitrophenyl (A2B2 and A3B2) and 4-nitrophenyl (A3B1 and A4B1) moieties at C4 significantly inhibited rhodamine 123 efflux at 5-25µM, showing that the mechanism of MDR reversal by these agents is P-gp transporter modulation. Same derivatives were also able to selectively lower the resistance of MES-SA/DX5 to doxorubicin. A2B2 bearing ethyl carboxylate at C5 had also high direct antitumoral effect (IC50 range: 3.77-15.60?M). Our findings suggest that SAR studies of DHPs may lead to the discovery of novel MDR reversal agents. PMID:25445037

Shekari, Farnaz; Sadeghpour, Hossein; Javidnia, Katayoun; Saso, Luciano; Nazari, Farhad; Firuzi, Omidreza; Miri, Ramin

2015-01-01

307

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

308

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

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

Li-Wu Fu

2012-05-01

309

Characterization and Identification of Multidrug Resistant Bacteria from Some Egyptian Patients  

OpenAIRE

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 ...

Seham Abdel-Shafi; Ouda, Sahar M.; Ibrahim Elbalat; Gamal Enan

2013-01-01

310

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

311

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

312

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

313

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

314

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

315

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

316

Tunicamycin Depresses P-Glycoprotein Glycosylation Without an Effect on Its Membrane Localization and Drug Efflux Activity in L1210 Cells  

OpenAIRE

P-glycoprotein (P-gp), also known as ABCB1, is a member of the ABC transporter family of proteins. P-gp is an ATP-dependent drug efflux pump that is localized to the plasma membrane of mammalian cells and confers multidrug resistance in neoplastic cells. P-gp is a 140-kDa polypeptide that is glycosylated to a final molecular weight of 170 kDa. Our experimental model used two variants of L1210 cells in which overexpression of P-gp was achieved: either by adaptation of parental cells (S) to vin...

Zdenka Sulová; Albert Breier; Dana Cholujová; Mário Šereš; Tatiana Buben?íkova

2011-01-01

317

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

318

Novel multidrug resistant microorganisms in critically ill: a potential threat.  

Science.gov (United States)

Infections due to multidrug resistant (MDR) pathogens are among the major threats in critically ill patients. Reduced vancomycin susceptibility in Staphylococcus aureus, high-level aminoglycoside resistance in enterococci, extended spectrum beta-lactamase and carbapenemases production in Enterobacteriaceae, carbapenem and colistin resistance in Pseudomonas spp. and Acinetobacter spp. are increasing in many intensive care units around the world. In the last few years some new anti-Gram-positive agents have been developed, whereas for Gram-negatives the available options are very limited. Infections control and antimicrobial stewardship programs are currently the only available options to avoid a further increase of these pathogens. PMID:24594917

Grossi, P A; Tebini, A; Dalla Gasperina, D

2015-01-01

319

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

320

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

Science.gov (United States)

Curcumin (CUR) is a phytochemical that inhibits the xenobiotic ABC efflux transporters implicated in cancer multidrug resistance (MDR), such as P-glycoprotein (P-gp), breast cancer resistance protein (BCRP) and multidrug resistance-associated proteins 1 and 5 (MRP1 and MRP5). The use of CUR in the clinic however, is complicated by its instability and poor pharmacokinetic profile. Monocarbonyl analogs of CUR (MACs) are compounds without CUR's unstable ?-diketone moiety and were reported to have improved stability and in vivo disposition. Whether the MACs can be used as MDR reversal agents is less clear, as the absence of a ?-diketone may negatively impact transporter inhibition. In this study, we investigated 23 heterocyclic cyclohexanone MACs for inhibitory effects against P-gp, BCRP, MRP1 and MRP5. Using flow cytometry and resistance reversal assays, we found that many of these compounds inhibited the transport activity of the ABC transporters investigated, often with much greater potency than CUR. Overall the analogs were most effective at inhibiting BCRP and we identified three compounds, A12 (2,6-bis((E)-2,5-dimethoxy-benzylidene)cyclohexanone), A13 (2,6-bis((E)-4-hydroxyl-3-methoxybenzylidene)-cyclohexanone) and B11 (3,5-bis((E)-2-fluoro-4,5-dimethoxybenzylidene)-1-methylpiperidin-4-one), as the most promising BCRP inhibitors. These compounds inhibited BCRP activity in a non-cell line, non-substrate-specific manner. Their inhibition occurred by direct transporter interaction rather than modulating protein or cell surface expression. From these results, we concluded that MACs, such as the heterocyclic cyclohexanone analogs in this study, also have potential as MDR reversal agents and may be superior alternatives to the unstable parent compound, CUR. PMID:25543853

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

2015-02-01

321

Chromosomal Instability Confers Intrinsic Multi-Drug Resistance  

OpenAIRE

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 ...

Lee, Alvin J. X.; Endesfelder, David; Rowan, Andrew J.; Walther, Axel; Birkbak, Nicolai J.; Futreal, P. Andrew; Downward, Julian; Szallasi, Zoltan; Tomlinson, Ian P. M.; Kschischo, Maik; Swanton, Charles

2011-01-01

322

Resource implications of patients with multidrug resistant tuberculosis  

OpenAIRE

BACKGROUND—Multidrug resistant tuberculosis (MDR TB) requires a complex drug regimen and lengthy multidisciplinary care. The financial cost of successful management of each case is potentially large.?METHODS—The costs of managing nine HIV negative patients with pulmonary MDR TB were compared with 18 age group and ethnicity matched controls with fully sensitive disease. Calculations included: cost of outpatient visits and inpatient stays including negative pressure i...

White, V.; Moore-gillon, J.

2000-01-01

323

Paclitaxel Nanocrystals for Overcoming Multidrug Resistance in Cancer  

OpenAIRE

Here we described a paclitaxel (PTX) nanocrystals formulation using D-?-tocopheryl polyethylene glycol 1000 succinate (TPGS) as the sole excipient for overcoming multidrug resistance (MDR), a key challenge in current cancer therapy. To the best of our knowledge, it is the first report on PTX nanocrystals which can reverse MDR. TPGS serves as a surfactant to stabilize the nanocrystals and a P-gp inhibitor to reverse MDR. The size and morphology of the nanocrystals were studied by transmission...

Liu, Yang; Huang, Leaf; Liu, Feng

2010-01-01

324

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

Science.gov (United States)

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

325

Metal nanobullets for multidrug resistant bacteria and biofilms.  

Science.gov (United States)

Infectious diseases were one of the major causes of mortality until now because drug-resistant bacteria have arisen under broad use and abuse of antibacterial drugs. These multidrug-resistant bacteria pose a major challenge to the effective control of bacterial infections and this threat has prompted the development of alternative strategies to treat bacterial diseases. Recently, use of metallic nanoparticles (NPs) as antibacterial agents is one of the promising strategies against bacterial drug resistance. This review first describes mechanisms of bacterial drug resistance and then focuses on the properties and applications of metallic NPs as antibiotic agents to deal with antibiotic-sensitive and -resistant bacteria. We also provide an overview of metallic NPs as bactericidal agents combating antibiotic-resistant bacteria and their potential in vivo toxicology for further drug development. PMID:25138828

Chen, Ching-Wen; Hsu, Chia-Yen; Lai, Syu-Ming; Syu, Wei-Jhe; Wang, Ting-Yi; Lai, Ping-Shan

2014-11-30

326

Structural basis and dynamics of multidrug recognition in a minimal bacterial multidrug resistance system.  

Science.gov (United States)

TipA is a transcriptional regulator found in diverse bacteria. It constitutes a minimal autoregulated multidrug resistance system against numerous thiopeptide antibiotics. Here we report the structures of its drug-binding domain TipAS in complexes with promothiocin A and nosiheptide, and a model of the thiostrepton complex. Drug binding induces a large transition from a partially unfolded to a globin-like structure. The structures rationalize the mechanism of promiscuous, yet specific, drug recognition: (i) a four-ring motif present in all known TipA-inducing antibiotics is recognized specifically by conserved TipAS amino acids; and (ii) the variable part of the antibiotic is accommodated within a flexible cleft that rigidifies upon drug binding. Remarkably, the identified four-ring motif is also the major interacting part of the antibiotic with the ribosome. Hence the TipA multidrug resistance mechanism is directed against the same chemical motif that inhibits protein synthesis. The observed identity of chemical motifs responsible for antibiotic function and resistance may be a general principle and could help to better define new leads for antibiotics. PMID:25489067

Habazettl, Judith; Allan, Martin; Jensen, Pernille Rose; Sass, Hans-Jürgen; Thompson, Charles J; Grzesiek, Stephan

2014-12-23

327

P-GLYCOPROTEIN QUANTITATION IN ACUTE LEUKEMIA  

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Full Text Available Multi drug resistance(MDR is a major problem in the treatment of cancer and hemalological malignancies. This resistance is multi factorial and is the result of decreased intra cellular drug accumulation. This is partly due to the presence of a 170KD intra membranous protein termed P-glycoprotein(P-gp that is an energy-dependent efflux pump which has increased expression on drug-resistance cells. In this study we identified the presence of P-gp by staining with Fluorescent Iso Thio Cyanate (FITC conjugated anti P-gp in acute leukemia patients and flow cytometry in addition to performing immunophenotype analysis and French, American British (FAB classification. Results revealed that one fifth of leuke¬mic patients expressed P-gp and this phenotype was more prevalent in Acute Undifferentiated Leukemia(AUL and Acute Myelogenous Leukemia (AML than in Acute Lymphoblastic Leukemia(ALL. Other findings showed a logical rela¬tionship between this phenotype and age groups. There was not any association between P-gp+ phenotype and FAB and Immunophenotyping sub classification, but there was a linear relationship between CD34 and CD7 expression and P-gp+ phenotype. The accumulation of P-gp molecule that was stated as Mean Fluores¬cence Intensity (MFI on the blasts1 membrane of AUL and AML patients showed marked increase in comparison to ALL. Furthermore MFI in P-gp+ relapsed patients was much more than P-gp+ pretreatment patients.

A.A. Pourfathollali

2003-06-01

328

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 effec...

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

2005-01-01

329

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

Science.gov (United States)

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

330

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)

331

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

332

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

Energy Technology Data Exchange (ETDEWEB)

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

333

Medical Treatment of Pulmonary Multidrug-Resistant Tuberculosis  

OpenAIRE

Treatment of multidrug-resistant tuberculosis (MDR-TB) is challenging because of the high toxicity of second-line drugs and the longer treatment duration required compared with drug-susceptible TB. The efficacy of treatment for MDR-TB is poorer than that for drug-susceptible TB. The selection of drugs in MDR-TB is based on previous treatment history, drug susceptibility results, and TB drug resistance patterns in the each region. Recent World Health Organization guidelines recommend the use o...

Shim, Tae Sun; Jo, Kyung-wook

2013-01-01

334

Multidrug-resistant Acinetobacter baumannii infection in children.  

Science.gov (United States)

Acinetobacter baumannii is a Gram-negative coccobacillus causing serious nosocomial infections. The recent emergence of strains of bacteria, which are resistant to common antibiotics, has made the treatment of these infections increasingly complex. We report the case of a young patient affected by AIDS, who suffered brain toxoplasmosis and sepsis due to multidrug-resistant A baumannii. This bacterial infection was successfully treated with colistin and tigecycline. In addition, we review recent literature on this topic, from the year 2000 to date. PMID:22688471

De Luca, Maia; Angelino, Giulia; Calò Carducci, Francesca Ippolita; Martino, Alessandra; Bernardi, Stefania; Bernaschi, Paola; Carletti, Michaela; D'Argenio, Patrizia; Palma, Paolo

2011-01-01

335

New Antibiotics in Development Against Multidrug-Resistant Bacteria  

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Full Text Available The rapid development of resistance to antimicrobial agents caused to investigate new antimicrobial agents for the treatment of various infections and new antibiotic effect mechanisms. Methicillin-resistant Staphylococcus aureus (MRSA, vancomycin-resistant enterococci (VRE, extended-spectrum beta-lactamase (ESBL Escherichia coli and Klebsiella spp., multidrug-resistant strains of Acinetobacter baumannii and Pseudomonas aeruginosa are the most important targets for new antibacterial. Development speed of new antibacterial agents decreased dramatically in the last ten years. Correct use of antibiotics should be the basic principle to avoid the development of resistance. In addition, although the development of new antibiotics is so important, the main purpose should be determining the new targets in order to minimize undesired effects and drug interactions, detecting new antibiotics effect mechanisms and developing new antibiotics for these purposes.

Soner Yýlmaz

2013-05-01

336

Tuberculosis Multidrogoresistente / Multidrug-resistant tuberculosis  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish La tuberculosis es una enfermedad infecciosa causada por el Mycobacterium tuberculosis. En el año 2010 se registraron 8.8 millones de casos incidentes en el mundo y en los últimos años han aparecido poblaciones bacterianas de micobacterias con resistencia a los fármacos de primera línea. Se ha defin [...] ido la presencia de resistencia a rifampicina e isoniacida como multidrogoresistencia, estimándose una incidencia mundial aproximada de 3.6%. Esta revisión de tema se centrará en la situación de la tuberculosis multidrogoresistente en el mundo, incluyendo un análisis regional de la casuística Colombiana. Se comentarán los principales mecanismos de resistencia del microorganismo, los genes implicados en la misma y los factores de riesgo asociados a la generación de resistencia en algunas comunidades. Abstract in english Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis. In 2010, there were 8.8 million incident cases in the world, and, in recent years, populations of mycobacteria with resistance to first-line drugs have emerged. The resistance to rifampin and isoniazid has been defined as mu [...] ltidrugresistant tuberculosis (TB MDR). TB MDR has an incidence of approximately 3.6% in the world. This review will focus on the current stage TB MDR in the world, including a regional analysis of Colombian cases. It will discuss the mechanism of resistance of the microorganism, genes involved, and the risk factors associated with the generation of resistance in some communities

German A, Acevedo; Agustín, Vega; Wellman, Ribón.

2013-12-01

337

Selective toxicity of NSC73306 in MDR1-positive cells as a new strategy to circumvent multidrug resistance in cancer.  

Science.gov (United States)

ATP-binding cassette (ABC) proteins include the best known mediators of resistance to anticancer drugs. In particular, ABCB1 [MDR1/P-glycoprotein (P-gp)] extrudes many types of drugs from cancer cells, thereby conferring resistance to those agents. Attempts to overcome P-gp-mediated drug resistance using specific inhibitors of P-gp has had limited success and has faced many therapeutic challenges. As an alternative approach to using P-gp inhibitors, we characterize a thiosemicarbazone derivative (NSC73306) identified in a generic screen as a compound that exploits, rather than suppresses, P-gp function to induce cytotoxicity. Cytotoxic activity of NSC73306 was evaluated in vitro using human epidermoid, ovarian, and colon cancer cell lines expressing various levels of P-gp. Our findings suggest that cells become hypersensitive to NSC73306 in proportion to the increased P-gp function and multidrug resistance (MDR). Abrogation of both sensitivity to NSC73306 and resistance to P-gp substrate anticancer agents occurred with specific inhibition of P-gp function using either a P-gp inhibitor (PSC833, XR9576) or RNA interference, suggesting that cytotoxicity was linked to MDR1 function, not to other, nonspecific factors arising during the generation of resistant or transfected cells. Molecular characterization of cells selected for resistance to NSC73306 revealed loss of P-gp expression and consequent loss of the MDR phenotype. Although hypersensitivity to NSC73306 required functional expression of P-gp, biochemical assays revealed no direct interaction between NSC73306 and P-gp. This article shows that NSC73306 kills cells with intrinsic or acquired P-gp-induced MDR and indirectly acts to eliminate resistance to MDR1 substrates. PMID:16651436

Ludwig, Joseph A; Szakács, Gergely; Martin, Scott E; Chu, Benjamin F; Cardarelli, Carol; Sauna, Zuben E; Caplen, Natasha J; Fales, Henry M; Ambudkar, Suresh V; Weinstein, John N; Gottesman, Michael M

2006-05-01

338

D-?-tocopherol polyethylene glycol succinate-based redox-sensitive paclitaxel prodrug for overcoming multidrug resistance in cancer cells.  

Science.gov (United States)

To overcome the multidrug resistance (MDR) of P-glycoprotein (P-gp) substrate anticancer drugs, such as paclitaxel (PTX), a novel dual-functional prodrug, D-?-tocopherol polyethylene glycol succinate (TPGS) based PTX prodrug (TPGS-S-S-PTX), was synthesized here to fulfill the synergistic effect of P-gp inhibiting and intracellular redox-sensitive release. The prodrug could self-assemble into stable micelles in physiological environment with a diameter of ?140 nm, while it disassociated in reductive condition and released PTX and TPGS active derivatives rapidly. High cell cytotoxicity in PTX-resistant human ovarian cell line A2780/T was observed with enhanced PTX accumulation due to the P-gp inhibition by the TPGS moiety. The IC50 of TPGS-S-S-PTX was 55% and 91% more effective than that of Taxol (clinical formulation of PTX) and uncleavable TPGS-C-C-PTX prodrug, respectively. This was found to be related with the increased apoptosis/necrosis and cell arrest in G2/M phase. In vivo evaluation of the TPGS-S-S-PTX prodrug exhibited an extended half-life, increased AUC (area under the concentration-time curve), enhanced tumor distribution and significant tumor growth inhibition with reduced side effects as compared to Taxol and TPGS-C-C-PTX. This prodrug has great potential in improving efficiency in the treatment of MDR tumors. PMID:25102234

Bao, Yuling; Guo, Yuanyuan; Zhuang, Xiangting; Li, Dan; Cheng, Bolin; Tan, Songwei; Zhang, Zhiping

2014-09-01

339

Effect of microRNA-21 on multidrug resistance reversal in A549/DDP human lung cancer cells.  

Science.gov (United States)

Lung cancer is a predominant cause of cancer-related mortality and numerous lung cancer patients succumb to the disease due to drug resistance. A number of microRNAs (miRNAs) are upregulated in cancer and are involved in tumorigenesis, functioning as oncogenes. Several functional studies have shown that miR-21 is important in carcinogenesis; however, none of these studies has investigated multidrug resistance (MDR) reversal in human lung cancer cells. In the present study, the effect of miR-21 on MDR reversal was analyzed in A549/DDP lung cancer cells. The data demonstrated the following after miR-21 silencing: Proliferation of the tumor cells was inhibited, cell apoptosis and oxidative damage were increased, the cell cycle was blocked at the G0/G1 phase, expression levels of P-glycoprotein were reduced, accumulation of Rhodamine 123 was increased, and the MDR-related genes encoding MDR1, MPR, glutathione S-transferase-?, B-cell lymphoma 2, cyclin-dependent kinase 1, cystathione and glutathione were downregulated. Further mechanistic analysis revealed that miR-21 silencing reduced AKT phosphorylation and transcriptional activation of E2F-1 and Twist. In conclusion, this study demonstrated that miR-21 silencing reversed lung cancer cell MDR by modulation of MDR-related gene expression and inhibition of the AKT signaling pathway, suggesting that miR-21 may be a potential therapeutic candidate in patients with MDR lung cancer. PMID:25323306

Dong, Zuoliang; Ren, Li; Lin, Li; Li, Jiang; Huang, Yiwen; Li, Jinhong

2015-01-01

340

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

Science.gov (United States)

Programmed cell death (PCD) is induced in Entamoeba histolytica by a variety of stimuli in vitro and in vivo. In mammals, intracellular acidification serves as a global switch for inactivating cellular processes and initiates molecular mechanisms implicated in the destruction of the genome. In contrast, intracellular alkalinization produced by P-glycoprotein overexpression in multidrug-resistant cells has been related to apoptosis resistance. Our previous studies showed that overexpression of E. histolytica P-glycoprotein (PGP) altered chloride-dependent currents and triggered trophozoite swelling, the reverse process of cell shrinkage produced during PCD. Here we showed that antisense inhibition of PGP expression produced a synchronous death of trophozoites and the enhancement of biochemical and morphological characteristics of PCD induced by G418. The nucleus was contracted, and the nuclear membrane was disrupted. Moreover, chromatin was extensively fragmented. Ca(2+) concentration was increased, while the intracellular pH (ipH) was acidified. In contrast, PGP overexpression prevented intracellular acidification and circumvented the apoptotic effect of G418. PMID:24012862

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

2013-11-01

341

Diversity and evolution of the small multidrug resistance protein family  

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Full Text Available Abstract Background Members of the small multidrug resistance (SMR protein family are integral membrane proteins characterized by four ?-helical transmembrane strands that confer resistance to a broad range of antiseptics and lipophilic quaternary ammonium compounds (QAC in bacteria. Due to their short length and broad substrate profile, SMR proteins are suggested to be the progenitors for larger ?-helical transporters such as the major facilitator superfamily (MFS and drug/metabolite transporter (DMT superfamily. To explore their evolutionary association with larger multidrug transporters, an extensive bioinformatics analysis of SMR sequences (> 300 Bacteria taxa was performed to expand upon previous evolutionary studies of the SMR protein family and its origins. Results A thorough annotation of unidentified/putative SMR sequences was performed placing sequences into each of the three SMR protein subclass designations, namely small multidrug proteins (SMP, suppressor of groEL mutations (SUG, and paired small multidrug resistance (PSMR using protein alignments and phylogenetic analysis. Examination of SMR subclass distribution within Bacteria and Archaea taxa identified specific Bacterial classes that uniquely encode for particular SMR subclass members. The extent of selective pressure acting upon each SMR subclass was determined by calculating the rate of synonymous to non-synonymous nucleotide substitutions using Syn-SCAN analysis. SUG and SMP subclasses are maintained under moderate selection pressure in comparison to integron and plasmid encoded SMR homologues. Conversely, PSMR sequences are maintained under lower levels of selection pressure, where one of the two PSMR pairs diverges in sequence more rapidly than the other. SMR genomic loci surveys identified potential SMR efflux substrates based on its gene association to putative operons that encode for genes regulating amino acid biogenesis and QAC-like metabolites. SMR subclass protein transmembrane domain alignments to Bacterial/Archaeal transporters (BAT, DMT, and MFS sequences supports SMR participation in multidrug transport evolution by identifying common TM domains. Conclusion Based on this study, PSMR sequences originated recently within both SUG and SMP clades through gene duplication events and it appears that SMR members may be evolving towards specific metabolite transport.

Turner Raymond J

2009-06-01

342

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

OpenAIRE

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

343

Chinese hamster pleiotropic multidrug-resistant cells are not radioresistant  

Energy Technology Data Exchange (ETDEWEB)

The inherent cellular radiosensitivity of a Chinese hamster ovary pleiotropic cell line that is multidrug resistant (CHRC5) was compared to that of its parental cell line (AuxB1). Radiation survival curve parameters n and D0 were 4.5 and 1.1 Gy, respectively, for the CHRC5 line and 5.0 and 1.2 Gy, respectively, for the parental line. Thus, the inherent radiosensitivity of the two lines was similar even though key intracellular free radical scavenging and detoxifying systems employing glutathione, glutathione transferase, and catalase produced enzyme levels that were 2.0-, 1.9-, and 1.9-fold higher, respectively, in the drug-resistant cell line. Glutathione depletion by buthionine sulfoximine resulted in the same extent of aerobic radiosensitization in both lines (approximately 10%). Incorporation of iododeoxyuridine into cellular DNA sensitized both cell lines to radiation. These studies indicate that pleiotropic drug resistance does not necessarily confer radiation resistance.

Mitchell, J.B.; Gamson, J.; Russo, A.; Friedman, N.; DeGraff, W.; Carmichael, J.; Glatstein, E.

1988-01-01

344

[Multidrug resistant Acinetobacter baumanii:clinical update and new highlights].  

Science.gov (United States)

The role of multidrug resistant Acinetobacter baumanii and its clinical relevance have been recently appreciated as a ubiquitous opportunistic nosocomial pathogen. Risk factors associated with A. baumanii infection include severe underlying diseases, previous surgery, invasive procedures, treatment with broad-spectrum antibiotics, length of hospital stay, admission to intensive care units (ICU). Carbapenem-multidrug resistant A. baumanii infections are probably associated to greater severity and more complications; in our cohort mortality was 49.3% and related mortality (within 72 hours) was 10.39%. However, severe underlying diseases probably play an important role in the clinical outcome of patients with MDR-C A. baumanii infection and controversy exists regarding the real mortality attributable to antimicrobial resistance because a high proportion of deaths took place > 7 days after diagnosis. Nevertheless, in our experience, carbapenem resistance, inappropriate therapy and monotherapy are associated to a higher mortality. Special attention should be paid to design well-controlled prospective clinical trials to determine the optimal antimicrobial therapy in critically ill patients suspected of having MDR Acinetobacter infection. PMID:20232019

Torres, Hernández A; Vázquez, E García; Yagüe, G; Gómez, J Gómez

2010-03-01

345

Concordance of resistance profiles in households of patients with multidrug-resistant tuberculosis.  

Science.gov (United States)

We estimated the proportion of household contacts whose drug-susceptibility test results matched those of the purported source patient with multidrug-resistant tuberculosis. Ninety-nine (88.4%) contacts had isolates resistant to isoniazid and rifampin, and 41 (36.6%) contacts had isolates with results that also matched the purported source for ethambutol, streptomycin, and pyrazinamide. PMID:24170196

Parr, Jonathan B; Mitnick, Carole D; Atwood, Sidney S; Chalco, Katiuska; Bayona, Jaime; Becerra, Mercedes C

2014-02-01

346

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

347

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

Directory of Open Access Journals (Sweden)

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

348

Intracellular pH and the control of multidrug resistance.  

OpenAIRE

Many anticancer drugs are classified as either weak bases or molecules whose binding to cellular structures is pH dependent. Accumulation of these drugs within tumor cells should be affected by transmembrane pH gradients. Indeed, development of multidrug resistance (MDR) in tumor cells has been correlated with an alkaline shift of cytosolic pH. To examine the role of pH in drug partitioning, the distribution of two drugs, doxorubicin and daunomycin, was monitored in fibroblasts and myeloma ce...

1994-01-01

349

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

Science.gov (United States)

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

350

Clofazimine in the treatment of multidrug-resistant tuberculosis.  

Science.gov (United States)

Clofazimine has shown activity against Mycobacterium tuberculosis, including multidrug-resistant strains in vitro and in animal studies. However, clinical experience with clofazimine in multidrug-resistant tuberculosis (MDR-TB) is scarce. We reported our clinical experience with 39 MDR-TB patients treated with combination regimens that included clofazimine. From January 2008 to March 2011, 39 patients received clofazimine for the treatment of MDR-TB in Shanghai Pulmonary Hospital. Patients had isolates resistant to a median of six drugs (range, 2-11 drugs). Of the 39 cases, 36 had cavitary changes noted on initial chest radiograph or chest computed tomography, and positive sputum-smear microscopy results at the time of MDR-TB diagnosis. At data censure, 15 of the 39 patients had successful therapy, with at least five consistently negative cultures documented for the final 12 months of treatment. Eleven continued to receive treatment. There were no deaths. Thirteen patients had a poor outcome, including four defaults and nine treatment failures. Culture conversion occurred in 22 cases at a median of 12 weeks. Side-effects occurred in 34 patients, mainly including skin discolouration, ichthyosis and gastrointestinal adverse events. No patients reported significant toxicity likely to be attributable to clofazimine therapy. Adverse events were managed by combinations of dose adjustment and symptom management. In our experience, clofazimine was well tolerated and may have efficacy in the treatment of MDR-TB. PMID:22192631

Xu, H-B; Jiang, R-H; Xiao, H-P

2012-11-01

351

How multidrug resistance in typhoid fever affects treatment options.  

Science.gov (United States)

Salmonella enterica serotype Typhi (S. Typhi) is an enteric pathogen that causes typhoid fever. The infection can be severe, with significant morbidity and mortality, requiring antimicrobial therapy. Cases of S. Typhi infection in the United States and other developed countries are often associated with travel to endemic regions. The empirical use of first-line drugs for therapy, including ampicillin, chloramphenicol, and trimethoprim/sulfamethoxazole, has resulted in transmissible multidrug resistance. With the global increase in multidrug-resistant S. Typhi, use of ciprofloxacin, with excellent oral absorption, few side effects, and cost-effectiveness, has become popular for treatment. However, decreased ciprofloxacin susceptibility due to point mutations in the S. Typhi genes gyrA and/or parC has caused treatment failures, necessitating alternative therapeutic options. S. Typhi is typically genetically homogenous, with phylogenetic and epidemiological studies showing that identical clones and diverse S. Typhi types often coexist in the same geographic region. Studies investigating point mutations have demonstrated that selective pressure from empirical use of first-line drugs and fluoroquinolones has led to the global emergence of haplotype H-58. Antibiotic resistance is subject to high selective pressure in S. Typhi and thus demands careful use of antimicrobials. PMID:25069595

Tatavarthy, Aparna; Luna, Vicki A; Amuso, Philip T

2014-09-01

352

Identification of an ABCB1 (P-glycoprotein)-positive carfilzomib-resistant myeloma subpopulation by the pluripotent stem cell fluorescent dye CDy1  

OpenAIRE

Multiple myeloma (MM) is characterized by the malignant expansion of differentiated plasma cells. Although many chemotherapeutic agents display cytotoxic activity toward MM cells, patients inevitably succumb to their disease because the tumor cells become resistant to the anticancer drugs. The cancer stem cell hypothesis postulates that a small subpopulation of chemotherapy-resistant cancer cells is responsible for propagation of the tumor. Herein we report that efflux of the pluripotent stem...

Hawley, Teresa S.; Riz, Irene; Yang, Wenjing; Wakabayashi, Yoshiyuki; Depalma, Louis; Chang, Young-tae; Peng, Weiqun; Zhu, Jun; Hawley, Robert G.

2013-01-01

353

Forced Expression of Heat Shock Protein 27 (Hsp27) Reverses P-Glycoprotein (ABCB1)-mediated Drug Efflux and MDR1 Gene Expression in Adriamycin-resistant Human Breast Cancer Cells*  

OpenAIRE

Mutant p53 accumulation has been shown to induce the multidrug resistance gene (MDR1) and ATP binding cassette (ABC)-based drug efflux in human breast cancer cells. In the present work, we have found that transcriptional activation of the oxidative stress-responsive heat shock factor 1 (HSF-1) and expression of heat shock proteins, including Hsp27, which is normally known to augment proteasomal p53 degradation, are inhibited in Adriamycin (doxorubicin)-resistant MCF-7 cells (MCF-7/adr). Such ...

Kanagasabai, Ragu; Krishnamurthy, Karthikeyan; Druhan, Lawrence J.; Ilangovan, Govindasamy

2011-01-01

354

Liposomal sphingomyelin influences the cellular lipid profile of human lymphoblastic leukemia cells without effect on P-glycoprotein activity.  

Science.gov (United States)

Sphingomyelin (SM)/cholesterol liposomes are currently investigated as drug carriers in cancer therapy. However, no data is available on the influence of SM itself on P-glycoprotein (P-gp) mediated multidrug resistance. P-gp is at least partly located in sphingolipid-enriched lipid raft domains of the plasma membrane, and its activity depends on the lipid profile of the membrane, which could be altered by therapeutical SM liposomes. Therefore, the aim of this study was to analyze the effect of liposomal SM on P-gp activity, P-gp distribution in microdomains, SM content of the membrane domains, and sensitivity of human lymphoblastic CEM cells toward cytotoxic drugs in vitro. Assays were conducted in CEM and multidrug resistant CEM/ADR5000 cells. SM-only liposomes were prepared by a newly developed ethanol injection protocol and thoroughly characterized. Inclusion of SM into the membrane was analyzed by fluorescence microscopy and flow cytometry. Influence of SM liposomes on P-gp activity was assessed by rhodamine efflux and calcein assay, and sensitivity toward cytotoxic drugs was analyzed by flow cytometric 7-AAD staining. Influence on P-gp distribution was analyzed by Western blot after density gradient centrifugation. SM 16:0, 18:0, and 24:1 were quantified by liquid chromatography coupled to tandem mass spectrometry. P-gp was mainly located in nonraft fractions, which did not change upon liposome treatment. Liposomes increased SM 16:0 and SM 24:1 content in nonraft domains, but not in raft domains of multidrug resistant cells. SM-only liposomes did not influence P-gp activity and chemosensitivity. In conclusion, SM-only liposomes in therapeutic amounts did not influence P-gp mediated multidrug resistance in CEM cells. PMID:23379426

Zembruski, Nadine C L; Nguyen, Chi D L; Theile, Dirk; Ali, Ramadan M M; Herzog, Melanie; Hofhaus, Götz; Heintz, Udo; Burhenne, Jürgen; Haefeli, Walter E; Weiss, Johanna

2013-03-01

355

Cell-free microfluidic determination of P-glycoprotein interactions with substrates and inhibitors.  

Science.gov (United States)

The membrane protein P-glycoprotein (P-gp) plays key roles in the oral bioavailability of drugs, their blood brain barrier passage as well as in multidrug resistance. For new drug candidates it is mandatory to study their interaction with P-gp, according to FDA and EMA regulations. The vast majority of these tests are performed using confluent cell layers of P-gp overexpressing cell lines that render these tests laborious. In this study, we introduce a cell-free microfluidic assay for the rapid testing of drug- P-gp interactions. Cell-derived vesicles are prepared from MDCKII-MDR1 overexpressing cells and immobilized on the surface of a planar microfluidic device. The drug is delivered continuously to the vesicles and calcein accumulation is monitored by means of a fluorescence assay and total internal reflection fluorescence (TIRF) microscopy. Only small amounts of compounds (~10 ?l) are required in concentrations of 5, 25 and 50 ?M for a test that provides within 5 min information on the apparent dissociation constant of the drug and P-gp. We tested 10 drugs on-chip, 9 of which are inhibitors or substrates of P-glycoprotein and one negative control. We benchmarked the measured apparent dissociation constants against an alternative assay on a plate reader and reference data from FDA. These comparisons revealed good correlations between the logarithmic apparent dissociation constants (R(2)?=?0.95 with ATPase assay, R(2)?=?0.93 with FDA data) and show the reliability of the rapid on-chip test. The herein presented assay has an excellent screening window factor (Z'-factor) of 0.8, and is suitable for high-throughput testing. PMID:24928366

Eyer, Klaus; Herger, Michael; Krämer, Stefanie D; Dittrich, Petra S

2014-12-01

356

Multiwavelength videomicrofluorometry for multiparametric investigations of multidrug resistance  

Science.gov (United States)

A major problem in the cancer chemotherapy is the development of resistance to a whole range of drugs not only similar to the drugs used for resistance induction but also to some functionally and structurally unrelated. It's one of the multifactorial causes of failure of chemotherapy. Thus it appears essential to evaluate the multi-drug resistance (MDR) in living cells populations to: detect the MDR phenotype, to discriminate between resistant and sensitive cells, to identify mechanisms which are involved in the induction or the reversion of resistance and to study the cytotoxic process. Such a challenge implies the use of multiparametric approach that has been possible using a protocol involving microfluorometry connected to numerical image analysis on single living cells. This protocol relays on the correlation existing between the decreased intracellular accumulation of some fluorescent probes such as Hoechst 33342 (Ho342) and Rhodamine 123 (R123) in resistant cells. The simultaneous estimation of the fluorescence intensities of these probes has required the use of a third probe, the Nile Red, for cell contour delineation. The analysis of parameters related to Ho342 and R123 allows the discrimination of sensitive and resistant cells. So the multiparametric approach using multi-wavelength image analysis, which appears to be a powerful technique, has allowed us to show on human lymphoblastoid CCRF-CEM cells lines that the cytotoxic effects could be different depending on the cell resistance or on the cytotoxic drug used: Adriamycine, Vinblastine and the different cell behavior could be used for cell differentiation.

Rocchi, Emmanuelle; Salmon, Jean-Marie; Vigo, Jean; Viallet, Pierre M.

1996-05-01

357

Comparative study on reversal efficacy of SDZ PSC 833, cyclosporin a and verapamil on multidrug resistance in vitro and in vivo  

Energy Technology Data Exchange (ETDEWEB)

A non-immunosuppressive cyclosporin, SDZ PSC 833 (PSC833), shows a reversal effect on multidrug resistance (MDR) by functional modulation of MDR1 gene product, P-glycoprotein. The objective of the present study was to compare the reversal efficacy of three multidrug resistance modulators, PSC833, cyclosporin A (CsA) and verapamil (Vp). PSC833 has approximately 3-10-fold greater potency than CsA and Vp with respect to the restoring effect on reduced accumulation of doxorubicin (ADM) and vincristine (VCR) in ADM-resistant K562 myelogenous leukemia cells (K562/ADM) in vitro and also on the sensitivity of K562/ADM to ADM and VCR in in vitro growth inhibition. The in vivo efficacy of a combination of modifiers (PSC833 and CsA: 50 mg/kg, Vp 100 mg/kg administered p.o. 4 h before the administration of anticancer drugs) with anticancer drugs (ADM 2.5 mg/kg i.p., Q4D days 1, 5 and 9, VCR 0.05 mg/kg i.p., QD days 1-5) was tested in ADM-resistant P388-bearing mice. PSC833 significantly enhanced the increase in life span by more than 80%, whereas CsA and Vp enhanced by less than 50%. This reversal potency, which exceeded that of CsA and Vp, was confirmed by therapeutic experiments using colon adenocarcinoma 26-bearing mice. These results demonstrated that PSC833 has significant potency to reverse MDR in vitro and in vivo, suggesting that PSC833 is a good candidate for reversing multidrug resistance in clinical situations. (orig.).

Watanabe, Toru [Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, Tokyo (Japan)]|[Tsukuba Research Inst., Sandoz Pharmaceuticals, Ltd., Ibaragi (Japan); Tsuge, Harumi [Inst. of Molecular and Cellular Biosciences, Tokyo Univ. (Japan); Oh-Hara, Tomoko [Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, Tokyo (Japan); Naito, Mikihiko [Inst. of Molecular and Cellular Biosciences, Tokyo Univ. (Japan); Tsuruo, Takashi [Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, Tokyo (Japan)]|[Inst. of Molecular and Cellular Biosciences, Tokyo Univ. (Japan)

1995-12-31

358

The Culturable Soil Antibiotic Resistome: A Community of Multi-Drug Resistant Bacteria  

OpenAIRE

Understanding the soil bacterial resistome is essential to understanding the evolution and development of antibiotic resistance, and its spread between species and biomes. We have identified and characterized multi-drug resistance (MDR) mechanisms in the culturable soil antibiotic resistome and linked the resistance profiles to bacterial species. We isolated 412 antibiotic resistant bacteria from agricultural, urban and pristine soils. All isolates were multi-drug resistant, of which...

Walsh, Fiona; Duffy, Brion

2013-01-01

359

Molecular characterization, spread and evolution of multidrug resistance in Salmonella enterica Typhimurium DT104  

OpenAIRE

Multidrug-resistant Salmonella enterica serovar Typhimurium phage type DT104 has emerged during the last decade as a global health problem because of its involvement in diseases in animals and humans. Multidrug-resistant DT104 strains are mostly resistant to ampicillin, chloramphenicol, streptomycin, sulfonamides and tetracyclines (ACSSuT resistance type). The genes coding for such resistances are clustered on the chromosome. This paper reviews new developments in the characterization of S. e...

Cloeckaert, Axel; Schwarz, Stefan

2001-01-01

360

Purification and characterization of N-glycosylation mutant mouse and human P-glycoproteins expressed in Pichia pastoris cells.  

Science.gov (United States)

P-glycoprotein confers multidrug resistance in mammalian cells and basic structure-function studies of it are germane to anti-cancer and anti-AIDS therapy. Pure, detergent-soluble mouse MDR3 and human MDR1 P-glycoproteins have recently been obtained in sufficient quantity for high-resolution structure analysis after expression in Pichia pastoris (N. Lerner-Marmarosh et al. (1999) J. Biol. Chem. 274, 34711-34718). The degree of glycosylation of these preparations was unknown, and was of relevance for crystallization studies. Therefore mutant proteins in which the N-glycosylation sites were eliminated (Asn --> Gln in mouse MDR3 Pgp, Asn --> Gln or Ala in human MDR1 Pgp) were expressed in P. pastoris and purified to homogeneity. Yields of mutant Pgp were the same as for parent wild-type proteins. Nucleotide-binding and catalytic (ATPase) characteristics were completely normal in the mutant proteins. Mass spectrometry indicated that mutant and wild-type proteins did not differ significantly in mass, demonstrating that the wild-type proteins contain no N-glycosylation. PMID:11361134

Urbatsch, I L; Wilke-Mounts, S; Gimi, K; Senior, A E

2001-04-01

361

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.  

Science.gov (United States)

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

362

Inhibition of glucosylceramide synthase does not reverse drug resistance in cancer cells.  

OpenAIRE

The multidrug-resistant cancer cell lines NCI/AdR(RES) and MES-SA/DX-5 have higher glycolipid levels and higher P-glycoprotein expression than the chemosensitive cell lines MCF7-wt and MES-SA. Inhibiting glycolipid biosynthesis by blocking glucosylceramide synthase has been proposed to reverse drug resistance in MDR cells by causing an increased accumulation of proapoptotic ceramide during treatment of cells with cytotoxic drugs. We treated both multidrug-resistant cell lines with the glucosy...

Norris-cervetto, E.; Callaghan, R; Platt, Fm; Dwek, Ra; Butters, Td

2004-01-01

363

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

Energy Technology Data Exchange (ETDEWEB)

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

364

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.

365

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

Energy Technology Data Exchange (ETDEWEB)

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

366

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

367

Effect of multidrug resistance gene-1(mdr1) overexpression on in-vitro uptake of 99mTc-sestaMIBI in murine L1210 leukemia cells  

International Nuclear Information System (INIS)

To determine whether 99mTc-MIBI is recognized by the multidrug resistant P-glycoprotein (Pgp), we have measured quantitatively 99mTc-MIBI uptake in cancer cells. The effects of various Pgp reversing agents on cellular 99mTc-MIBI uptake were also investigated in the presence of multidrug resistance gene-1 (mdr 1 gene) overexpression. We measured percentage uptake of 99mTc-MIBI at different incubation temperatures both in mdr1 positive and negative cells. The effects of verapamil, cyclosporin, and dipyridamole on cellular uptake of 99mTc-MIBI were also evaluated with or without overexpression of mdr1 gene in cultured murine leukemia L1210 cells. The mdr1 gene expressing cell lines were effectively induced in in vitro with continuous application of low-dose adriamycin or vincristine. Cellular uptake of 99mTc-MIBI was higher in mdr1 negative L1210 cells than those of mdr1 positive cells, and higher when incubated in 37 .deg. C than 4 .deg. C. In the presence of verapamil, cyclosporin or dipyridamole, 99mTc-MIBI uptake was increased upto 604% in mdr1 positive cells. Cellular uptake of 99mTc-MIBI is lower in leukemia cells over-expressing mdr1 gene, and MDR-reversing agents increase cellular uptake. These results suggest the 99mTc-MIBI can be used for characterizing Pgp expression and developing MDR-reversing agents in vitro

368

Human ABCB1 (P-glycoprotein) and ABCG2 Mediate Resistance to BI 2536, a Potent and Selective Inhibitor of Polo-like Kinase 1  

OpenAIRE

The overexpression of the serine/threonine specific polo-like kinase 1 (Plk1) has been detected in various types of cancer, and thus has fast become an attractive therapeutic target for cancer therapy. BI 2536 is the first selective inhibitor of Plk1 that inhibits cancer cell proliferation by promoting G2/M cell cycle arrest at nanomolar concentrations. Unfortunately, alike most chemotherapeutic agents, the development of acquired resistance to BI 2536 is prone to present a significant therap...

Wu, Chung-pu; Hsiao, Sung-han; Sim, Hong-may; Luo, Shi-yu; Tuo, Wei-cherng; Cheng, Hsing-wen; Li, Yan-qing; Huang, Yang-hui; Ambudkar, Suresh V.

2013-01-01

369

Olomoucine II, but Not Purvalanol A, Is Transported by Breast Cancer Resistance Protein (ABCG2) and P-Glycoprotein (ABCB1)  

OpenAIRE

Purine cyclin-dependent kinase inhibitors have been recognized as promising candidates for the treatment of various cancers; nevertheless, data regarding interaction of these substances with drug efflux transporters is still lacking. Recently, we have demonstrated inhibition of breast cancer resistance protein (ABCG2) by olomoucine II and purvalanol A and shown that these compounds are able to synergistically potentiate the antiproliferative effect of mitoxantrone, an ABCG2 substrate. In this...

Hofman, Jakub; Kuc?era, Radim; Cihalova, Daniela; Klimes, Jiri; Ceckova, Martina; Staud, Frantisek

2013-01-01

370

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)

371

Comparative Genome Sequence Analysis of Multidrug-Resistant Acinetobacter baumannii? †  

Science.gov (United States)

The recent emergence of multidrug resistance (MDR) in Acinetobacter baumannii has raised concern in health care settings worldwide. In order to understand the repertoire of resistance determinants and their organization and origins, we compared the genome sequences of three MDR and three drug-susceptible A. baumannii isolates. The entire MDR phenotype can be explained by the acquisition of discrete resistance determinants distributed throughout the genome. A comparison of closely related MDR and drug-susceptible isolates suggests that drug efflux may be a less significant contributor to resistance to certain classes of antibiotics than inactivation enzymes are. A resistance island with a variable composition of resistance determinants interspersed with transposons, integrons, and other mobile genetic elements is a significant but not universal contributor to the MDR phenotype. Four hundred seventy-five genes are shared among all six clinical isolates but absent from the related environmental species Acinetobacter baylyi ADP1. These genes are enriched for transcription factors and transporters and suggest physiological features of A. baumannii that are related to adaptation for growth in association with humans. PMID:18931120

Adams, Mark D.; Goglin, Karrie; Molyneaux, Neil; Hujer, Kristine M.; Lavender, Heather; Jamison, Jennifer J.; MacDonald, Ian J.; Martin, Kristienna M.; Russo, Thomas; Campagnari, Anthony A.; Hujer, Andrea M.; Bonomo, Robert A.; Gill, Steven R.

2008-01-01

372

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

373

Demethoxycurcumin Modulates Human P-Glycoprotein Function via Uncompetitive Inhibition of ATPase Hydrolysis Activity.  

Science.gov (United States)

Curcuminoids are major components of Curcuma longa L., which is widely used as spice in food. This study aimed at identifying whether curcumin, demethoxycurcumin, and bisdemethoxycurcumin could modulate efflux function of human P-glycoprotein and be used as chemosensitizers in cancer treatments. Without altering P-glycoprotein expression levels and conformation, the purified curcuminoids significantly inhibited P-glycoprotein efflux function. In rhodamine 123 efflux and calcein-AM accumulation assays, demethoxycurcumin demonstrated the highest inhibition potency (inhibitory IC50 = 1.56 ± 0.13 ?M) among the purified curcuminoids, as well as in the fold of reversal assays. Demethoxycurcumin inhibited P-glycoprotein-mediated ATP hydrolysis under concentrations of additive natural product in combination with chemotherapeutic agents in drug-resistant cancers. PMID:25594233

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

2015-01-28

374

Functional imaging of multidrug resistance in an orthotopic model of osteosarcoma using 99mTc-sestamibi  

International Nuclear Information System (INIS)

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 99mTc-sestamibi. Doxorubicin-sensitive (143B-luc+) and resistant (MNNG/HOS-luc+) 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 99mTc-sestamibi dynamic study was performed. A subset of animals was pre-treated with an MDR inhibitor (PSC833). Images were analysed for calculation of 99mTc-sestamibi washout half-life (t1/2), 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 t1/2 of 99mTc-sestamibi was significantly shorter (p + tumours (t1/2 = 87.3 ± 15.7 min) than in drug-sensitive 143B-luc+ tumours (t1/2 = 161.0 ± 47.4 min) and decreased significantly with PSC833 (t1/2 = 173.0 ± 24.5 min, p + tumours. The T/NT ratio was significantly lower (p + tumours than in 143B-lucp>+ tumours than in 143B-luc+ 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 99mTc-sestamibi washout provides information on the functional activity of MDR related to P-glycoprotein expression and its pharmacological inhibition in osteosarcoma. (orig.)

375

P-glycoprotein inhibitors of natural origin as potential tumor chemo-sensitizers: A review  

Science.gov (United States)

Resistance of solid tumors to treatment is significantly attributed to pharmacokinetic reasons at both cellular and multi-cellular levels. Anticancer agent must be bio-available at the site of action in a cytotoxic concentration to exert its proposed activity. P-glycoprotein (P-gp) is a member of the ATP-dependent membrane transport proteins; it is known to pump substrates out of cells in ATP-dependent mechanism. The over-expression of P-gp in tumor cells reduces the intracellular drug concentrations, which decreases the cytotoxicity of a broad spectrum of antitumor drugs. Accordingly, P-gp inhibitors/blockers are potential enhancer for the cellular bioavailability of several clinically important anticancer drugs such as, anthracyclines, taxanes, vinca alkaloids, and podophyllotoxins. Besides several chemically synthesized P-gp inhibitors/blockers, some naturally occurring compounds and plant extracts were reported for their modulation of multidrug resistance; however, this review will focus only on major classes of naturally occurring inhibitors viz., flavonoids, coumarins, terpenoids, alkaloids and saponins.

Abdallah, Hossam M.; Al-Abd, Ahmed M.; El-Dine, Riham Salah; El-Halawany, Ali M.

2014-01-01

376

Evidence for p-glycoprotein modification of insecticide toxicity in mosquitoes of the Culex pipiens complex.  

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Pesticide resistance has parallels with multi-drug resistance syndrome of tumours in clinical medicine, which has been linked to an ATP-dependent pump, p-glycoprotein (P-gp). P-gps pump drugs out of the cell, thereby reducing cellular concentrations of the chemical. P-gps have been found in several invertebrate species and have been shown to provide a defence against environmental xenobiotics, including pesticides. This study used a model cell culture system to investigate the interaction of pesticides with P-gp. Ivermectin and endosulfan were shown to be strong inhibitors of dye transport out of cells, which is a standard measure of P-gp modulation. We then investigated the action of a P-gp inhibitor, verapamil (calcium channel blocker), on insecticide toxicity to fourth-instar mosquito larvae of the Culex pipiens L. complex (Diptera: Culicidae). Verapamil increased toxicity to examples of three insecticide classes (cypermethrin, endosulfan, ivermectin), but not to chlorpyrifos (organophosphate). The discovery of a novel protective mechanism in mosquitoes, with a wide substrate range, has implications for the control of important pest and vector species. PMID:12109718

Buss, D S; McCaffery, A R; Callaghan, A

2002-06-01

377

Polymorphisms in the multiple drug resistance protein 1 and in P-glycoprotein 1 are associated with time to event outcomes in patients with advanced multiple myeloma treated with bortezomib and pegylated liposomal doxorubicin  

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Single nucleotide polymorphisms (SNPs) in the multiple drug resistance protein 1 (MRP1) and P-glycoprotein 1 (MDR1) genes modulate their ability to mediate drug resistance. We therefore sought to retrospectively evaluate their influence on outcomes in relapsed and/or refractory myeloma patients treated with bortezomib or bortezomib with pegylated liposomal doxorubicin (PLD). The MRP1/R723Q polymorphism was found in five subjects among the 279 patient study population, all of whom received PLD?+?bortezomib. Its presence was associated with a longer time to progression (TTP; median 330 vs. 129 days; p?=?0.0008), progression-free survival (PFS; median 338 vs. 129 days; p?=?0.0006), and overall survival (p?=?0.0045). MDR1/3435(C?>?T), which was in Hardy–Weinberg equilibrium, showed a trend of association with PFS (p?=?0.0578), response rate (p?=?0.0782) and TTP (p?=?0.0923) in PLD?+?bortezomib patients, though no correlation was found in the bortezomib arm. In a recessive genetic model, MDR1/3435 T was significantly associated with a better TTP (p?=?0.0405) and PFS (p?=?0.0186) in PLD?+?bortezomib patients. These findings suggest a potential role for MRP1 and MDR1 SNPs in modulating the long-term outcome of relapsed and/or refractory myeloma patients treated with PLD?+?bortezomib. Moreover, they support prospective studies to determine if such data could be used to tailor therapy to the genetic makeup of individual patients. PMID:20532504

Buda, Gabriele; Ricci, Deborah; Huang, C. Chris; Favis, Reyna; Cohen, Nadine; Zhuang, Sen H.; Harousseau, Jean-Luc; Sonneveld, Pieter; Bladé, Joan

2010-01-01

378

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  

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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

379

A multifaceted analysis of HIV-1 protease multidrug resistance phenotypes  

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Full Text Available Abstract Background Great strides have been made in the effective treatment of HIV-1 with the development of second-generation protease inhibitors (PIs that are effective against historically multi-PI-resistant HIV-1 variants. Nevertheless, mutation patterns that confer decreasing susceptibility to available PIs continue to arise within the population. Understanding the phenotypic and genotypic patterns responsible for multi-PI resistance is necessary for developing PIs that are active against clinically-relevant PI-resistant HIV-1 variants. Results In this work, we use globally optimal integer programming-based clustering techniques to elucidate multi-PI phenotypic resistance patterns using a data set of 398 HIV-1 protease sequences that have each been phenotyped for susceptibility toward the nine clinically-approved HIV-1 PIs. We validate the information content of the clusters by evaluating their ability to predict the level of decreased susceptibility to each of the available PIs using a cross validation procedure. We demonstrate the finding that as a result of phenotypic cross resistance, the considered clinical HIV-1 protease isolates are confined to ~6% or less of the clinically-relevant phenotypic space. Clustering and feature selection methods are used to find representative sequences and mutations for major resistance phenotypes to elucidate their genotypic signatures. We show that phenotypic similarity does not imply genotypic similarity, that different PI-resistance mutation patterns can give rise to HIV-1 isolates with similar phenotypic profiles. Conclusion Rather than characterizing HIV-1 susceptibility toward each PI individually, our study offers a unique perspective on the phenomenon of PI class resistance by uncovering major multidrug-resistant phenotypic patterns and their often diverse genotypic determinants, providing a methodology that can be applied to understand clinically-relevant phenotypic patterns to aid in the design of novel inhibitors that target other rapidly evolving molecular targets as well.

Doherty Kathleen M

2011-12-01

380

Reversal of multidrug resistance in vitro by co-delivery of MDR1 targeting siRNA and doxorubicin using a novel cationic poly(lactide-co-glycolide) nanoformulation.  

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Over expression of drug efflux transporters such as P-glycoprotein (P-gp) cumulatively leading to multidrug resistance (MDR) embodies a major hindrance for successful cancer therapy. A paradigm nanomedicinal approach involving an anticancer drug and modulators of drug resistance within one multifunctional nanocarrier-based delivery system represent an ideal modality for the treatment of MDR. In this regards, we have developed a cationic polymeric nanoparticulate system loaded with MDR1-siRNA and doxorubicin. Results indicated augmented synergistic effect of combinational nanoformulation in overcoming MDR in MCF-7/ADR cells. Therefore, the above regime could be a promising co-delivery system for effective therapy of drug resistant breast cancer. PMID:25178825

Misra, Ranjita; Das, Manasi; Sahoo, Bhabani Sankar; Sahoo, Sanjeeb K

2014-11-20

381

Inhibitory effects of terpenoids on multidrug resistance-associated protein 2- and breast cancer resistance protein-mediated transport.  

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The possibility of interactions between natural products/supplements and conventional prescription medicines is one of the most important issues in pharmacotherapeutic safety. Recently, we reported that some terpenoids such as (R)-(+)-citronellal and glycyrrhetic acid, which are present in herbal medicines, can act as inhibitors of P-glycoprotein (MDR1/ABCB1). In the present study, the effects of seven terpenoids on multidrug resistance-associated protein 2 (MRP2/ABCC2) and breast cancer resistance protein (BCRP/ABCG2)-mediated transport were investigated in vitro. Membrane vesicles were prepared from MRP2 cDNA transfected Sf9 cells derived from pupal ovarian tissue of Spodoptera frugiperda, a fall armyworm, and BCRP cDNA transfected LLC-PK1 cells derived from porcine kidney. MRP2- or BCRP-mediated efflux transport was measured as ATP-dependent accumulation of [(3)H]estradiol 17-beta-d-glucuronide (E(2)17betaG) into membrane vesicles collected by a rapid filtration technique. The effects of (R)-(+)-citronellal, (S)-(-)-beta-citronellol, alpha-terpinene, terpinolene, (-)-beta-pinene, abietic acid, and glycyrrhetic acid on the intravesicular accumulation of [(3)H]E(2)17betaG were examined. Large decreases in the [(3)H]E(2)17betaG accumulation into vesicles from MRP2-overexpressing Sf9 cells were observed in the presence of glycyrrhetic acid and abietic acid, and their IC(50) values were about 20 and 51 microM, respectively. [(3)H]E(2)17betaG accumulation into vesicles from BCRP-overexpressing LLC-PK1 cells was suppressed by only glycyrrhetic acid, with an IC(50) value of about 39 microM. Other terpenoids used in this study did not alter the ATP-dependent accumulation of [(3)H]E(2)17betaG. These findings suggest that glycyrrhetic acid and abietic acid can potently inhibit MRP2- or BCRP-mediated membrane transport and may interact with their substrates in pharmacokinetic processes. PMID:18436619

Yoshida, Naoko; Takada, Tappei; Yamamura, Yoshikazu; Adachi, Isao; Suzuki, Hiroshi; Kawakami, Junichi

2008-07-01

382

Establishment of a Multidrug Resistance Cell Line A549/cDDP of Human Lung Adenocarcinoma and Expression Analysis of Multidrug Resistance-Associated Genes  

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Full Text Available Background and objective It has been proven that chemotherapy failure caused by multidrug resistance in lung tumor cells is the main cause for the patient's survival rate. The aim of this study is to establish a multidrug resistance cell line of human lung adenocarcinoma and study the mechanism of multidrug resistance. Methods Human lung adenocarcinoma cell line A549 was induced to multidrug resistance cell line A549/cDDP by intermittentadministration of high dose of cisplatin (cDDP. The multidrug resistance was detected by using MTT assay. The levels of expression of MDR-1 gene-coded P-glycoportein (P-gp, multidrug resistance-associated protein (MRP, and GSH/GST were examined by flow cytometric assay. The levels of expression of MDR and MRP gene were also detected by RTPCR in both A549/cDDP and A549 cell lines. Results A549/cDDP was resistant to many anti-tumor agents. The IC50 of A549/cDDP was 16.87 times higher than that of A549. The expressions of P-gp and MRP in A549/cDDP were increased significantly to (70.5±4.9? and (29.4±2.9?, respectively, vs (42.4±5.6? and (21.4±3.5? in A549. There was no difference of the GSH/GST expression between A549/cDDPand A549 cells. Conclusion A549/cDDP is a model with multidrug resistance and the levels of MDR and MRP mRNA expressions are remarkably higher in A549/cDDP than those in A549.

Yongcheng PAN

2009-03-01

383

Modulation of P-glycoprotein function by sphingosine kinase-1 in brain endothelial cells.  

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P-glycoprotein (P-gp), an ABC-transporter highly expressed in brain capillaries, protects the brain by extruding xenobiotics. However, its overexpression has also been associated with the multidrug resistance phenotype in tumors. Here, we have investigated the regulation of P-gp transport activity by sphingosine kinase 1 (SphK-1) in brain endothelial cells. We first demonstrated that SphK-1 is overexpressed in endothelial cells (EC) isolated from rat brain tumors compared with EC from normal brain. We also provide evidence that the overexpression of SphK-1 in the cerebral EC line RBE4 leads to the up-regulation of P-gp, both at the gene and protein levels, and that this modulation depends on the catalytic activity of SphK-1. Moreover, we determined the effect of sphingosine-1-phosphate (S1P), the product of SphK-1, on P-gp function. S1P strongly stimulates P-gp transport activity, without modulating its expression. Finally, we found that the S1P-mediated stimulation of P-gp activity is mediated by S1P-1 and S1P-3 receptors at the RBE4 cell surface. Altogether, these results indicate that SphK-1 and its product S1P are involved in the control of P-gp activity in RBE4 cells. Since SphK-1 is overexpressed in EC from brain tumors, these data also suggest that this kinase and its product could contribute to the acquisition and the maintenance of the multidrug resistance phenotype in brain tumor-derived endothelial cells. PMID:17316399

Pilorget, Anthony; Demeule, Michel; Barakat, Stéphane; Marvaldi, Jacques; Luis, José; Béliveau, Richard

2007-03-01

384

Imaging multidrug resistance with 4-[18F]fluoropaclitaxel  

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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

385

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; Corde