Identification of the synthetic surfactant nonylphenol ethoxylate: a P-glycoprotein substrate in human urine

1998 ◽  
Vol 274 (6) ◽  
pp. F1127-F1139 ◽  
Author(s):  
Jeffrey H. M. Charuk ◽  
Arthur A. Grey ◽  
Reinhart A. F. Reithmeier
Keyword(s):  
Cyclosporin A ◽  
Drug Transport ◽  
Mdck Cells ◽  
Chinese Hamster ◽  
Multidrug Resistant ◽  
The Body ◽  
Transepithelial Transport ◽  
Synthetic Surfactant ◽  
Nonylphenol Ethoxylate ◽  
P Glycoprotein

P-glycoprotein (Mdr1p) is an ATP-dependent drug efflux pump that is overexpressed in multidrug-resistant cells and some cancers. Mdr1p is also expressed in normal tissues like the kidney, where it can mediate transepithelial drug transport. A human urinary compound that reverses multidrug resistance and blocks [3H]azidopine photolabeling of P-glycoprotein was purified to homogeneity and identified by 1H-NMR and mass spectrometry as the synthetic surfactant nonylphenol ethoxylate (NPE). Multidrug-resistant Chinese hamster ovary (CHO) C5 cells accumulated less [3H]NPE than parental drug-sensitive Aux-B1 cells, and Mdr1p substrates, verapamil and cyclosporin A, increased this surfactant’s accumulation in C5 cells. NPE blocked the net transepithelial transport (basolateral to apical) of [3H]cyclosporin A in epithelia formed by Madin-Darby canine kidney (MDCK) cells. Net transepithelial transport (basal to apical) of [3H]NPE was demonstrated in MDCK cells and was inhibited by cyclosporin A. These findings show NPE is a Mdr1p substrate excreted into urine by kidney P-glycoprotein. NPE is a widely used surfactant and a known hormone disrupter that is readily absorbed orally or topically. The current findings indicate the function of kidney Mdr1p may be to eliminate exogenous compounds from the body.

Differential interaction of human renal P-glycoprotein with various metabolites and analogues of cyclosporin A

1995 ◽  
Vol 269 (1) ◽  
pp. F31-F39
Author(s):  
J. H. Charuk ◽  
P. Y. Wong ◽  
R. A. Reithmeier
Keyword(s):  
Cyclosporin A ◽  
Drug Transport ◽  
Multidrug Resistant ◽  
Drug Binding ◽  
Future Design ◽  
Drug Binding Site ◽  
P Glycoprotein ◽  
Low Concentrations ◽  
20 Nm ◽  
Design And Testing

Interactions of P-glycoprotein with several analogues and metabolites of cyclosporin A were studied to gain a better understanding of this immunosuppressant's mechanism of excretion and nephrotoxicity. Incorporation of [3H]azidopine into human renal P-glycoprotein in the presence of various concentrations of different cyclosporins was quantitated. Competitive [3H]azidopine photolabeling and 3H drug transport assays of CHRC5 multidrug-resistant cells were also conducted to evaluate effects of cyclosporins on P-glycoprotein function. Cyclosporins A [half-maximal inhibition constant (K0.5) = 20 nM] and G (K0.5 = 40 nM) blocked [3H]azidopine photolabeling of renal P-glycoprotein at very low concentrations, whereas higher concentrations of cyclosporin C (K0.5 = 500 nM) and metabolites 1, 17, and 21 (K0.5 = 200 nM) were required to inhibit photolabeling. Metabolites H and 8 were ineffective in inhibition of [3H]azidopine photolabeling of human renal P-glycoprotein. Similarly, cyclosporins A, C, and G were the best inhibitors of [3H]azidopine photolabeling of P-glycoprotein in multidrug-resistant C5 cells; the various metabolites were less effective. Cyclosporins A, C, and G also enhanced cellular accumulation of [3H]cyclosporin A and several other 3H-labeled compounds known to be transported by P-glycoprotein in multidrug-resistant C5 cells. Differential affinities of cyclosporin A metabolites for P-glycoprotein suggest considerable drug-binding site specificity. Our current hypothesis is that cyclosporin A may be more nephrotoxic than its metabolites by virtue of its superior ability to bind to and competitively inhibit urinary excretion of an endogenous P-glycoprotein substrate. Our findings provide the basis for future design and testing of new cyclosporin derivatives that have immunosuppressive activity yet may be less nephrotoxic because of their poor interaction with renal P-glycoprotein.

Inhibition of P-glycoprotein by cyclosporin A analogues and metabolites

1999 ◽  
Vol 77 (1) ◽  
pp. 47-58 ◽  
Author(s):  
Michel Demeule ◽  
Alain Laplante ◽  
Arash Sepehr-Araé ◽  
Édith Beaulieu ◽  
Diana Averill-Bates ◽  
...  
Keyword(s):  
Atpase Activity ◽  
Cyclosporin A ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Multidrug Resistant ◽  
Hydroxyl Group ◽  
Glycoprotein P ◽  
Ovary Cells ◽  
Psc 833 ◽  
P Glycoprotein

The interaction between P-glycoprotein (P-gp) from membranes isolated from multidrug-resistant Chinese hamster ovary cells and cyclosporin A (CsA) analogues and its metabolites was characterized. Screening of these latter as chemosensitizers was performed using three different assays: (i) vinblastine uptake, (ii) photoaffinity labeling by [125I]iodoaryl azidoprazosin, and (iii) P-gp ATPase activity. Oxidation of the hydroxyl group at position 1 of CsA (200-096), CsG (215-834), or CsD (PSC-833) increased their inhibition of P-gp. CsA analogues (208-032, 208-183) modified at position 11 retained their ability to inhibit P-gp while analogues modified at position 2 (CsC and CsD) lost their efficiency. The inhibitions induced by metabolites of CsA were also compared to those obtained with CsG metabolites. From all the molecules tested, PSC-833 and 280-446 peptolide were the strongest inhibitors. Our results indicate that modifications of CsA analogues at position 1 and 2 are critical for their interaction with P-gp and that CsA metabolites retain a portion of the inhibitory activity of the parent drug.Key words: P-glycoprotein, cyclosporin A, vinblastine uptake, photolabeling, ATPase activity.

scholarly journals The Fluorescent Probe Bodipy-FL-Verapamil Is a Substrate for Both P-glycoprotein and Multidrug Resistance-related Protein (MRP)-1

2002 ◽  
Vol 50 (5) ◽  
pp. 731-734 ◽  
Author(s):  
Enrico Crivellato ◽  
Luigi Candussio ◽  
Anna M. Rosati ◽  
Fiora Bartoli-Klugmann ◽  
Franco Mallardi ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Drug Transport ◽  
Mrna Level ◽  
Fluorescent Microscopy ◽  
Flow Cytometric Analysis ◽  
Cell Types ◽  
Multidrug Resistant ◽  
Related Protein ◽  
P Glycoprotein ◽  
Multidrug Resistance Related Protein

Several fluorescent probes have been used in functional studies to analyze drug transport in multidrug-resistant cells by fluorescent microscopy. Because many of these molecules have some drawbacks, such as toxicity, nonspecific background, or accumulation in mitochondria, new fluorescent compounds have been proposed as more useful tools. Among these substances, Bodipy-FL-Verapamil, a fluorescent conjugate of the drug efflux blocker verapamil, has been used to study P-glycoprotein activity in different cell types. In this study we tested by fluorescent microscopy the accumulation of Bodipy-FL- Verapamil in cell lines that overexpress either P-glycoprotein (P-gp) or multidrug resistance-related protein 1 (MRP1). Expression of P-gp and MRP1 was evaluated at the mRNA level by RT-PCR technique and at the protein level by flow cytometric analysis using C219 and MRP-m6 monoclonal antibodies. Results indicate that Bodipy-FL-Verapamil is actually a substrate for both proteins. As a consequence, any conclusion about P-gp activity obtained by the use of Bodipy-FL-Verapamil as fluorescent tracer should be interpreted with caution.

scholarly journals A possible role for a mammalian facilitative hexose transporter in the development of resistance to drugs.

1991 ◽  
Vol 11 (7) ◽  
pp. 3407-3418 ◽  
Author(s):  
J C Vera ◽  
G R Castillo ◽  
O M Rosen
Keyword(s):  
Xenopus Oocytes ◽  
Glucose Transporter ◽  
Cytochalasin B ◽  
Chinese Hamster ◽  
Multidrug Resistant ◽  
Xenopus Laevis Oocytes ◽  
Hexose Transporter ◽  
P Glycoprotein ◽  
Glut1 Protein ◽  
Facilitative Glucose Transporter

We show that D- but not L-hexoses modulate the accumulation of radioactive vinblastine in injected Xenopus laevis oocytes expressing the murine Mdr1b P-glycoprotein. We also show that X. laevis oocytes injected with RNA encoding the rat erythroid/brain glucose transport protein (GLUT1) and expressing the corresponding functional transporter exhibit a lower accumulation of [3H]vinblastine and show a greater capacity to extrude the drug than do control oocytes not expressing the rat GLUT1 protein. Cytochalasin B and phloretin, two inhibitors of the mammalian facilitative glucose transporters, can overcome the reduced drug accumulation conferred by expression of the rat GLUT1 protein in Xenopus oocytes but have no significant effect on the accumulation of drug by Xenopus oocytes expressing the mouse Mdr1b P-glycoprotein. These drugs also increase the accumulation of [3H]vinblastine in multidrug-resistant Chinese hamster ovary cells. Cytochalasin E, an analog of cytochalasin B that does not affect the activity of the facilitative glucose transporter, has no effect on the accumulation of vinblastine by multidrug-resistant Chinese hamster cells or by oocytes expressing either the mouse Mdr1b P-glycoprotein or the GLUT1 protein. In all three cases, the drug verapamil produces a profound effect on the cellular accumulation of vinblastine. Interestingly, although immunological analysis indicated the presence of massive amounts of P-glycoprotein in the multidrug-resistant cells, immunological and functional studies revealed only a minor increase in the expression of a hexose transporter-like protein in resistant versus drug-sensitive cells. Taken together, these results suggest the participation of the mammalian facilitative glucose transporter in the development of drug resistance.

Modeling of P-glycoprotein-involved epithelial drug transport in MDCK cells

1999 ◽  
Vol 277 (1) ◽  
pp. F84-F96 ◽  
Author(s):  
Shinya Ito ◽  
Cindy Woodland ◽  
Balázs Sarkadi ◽  
Guido Hockmann ◽  
Scott E. Walker ◽  
...  
Keyword(s):  
Drug Transport ◽  
Diffusion Processes ◽  
Efflux Pump ◽  
Mdck Cells ◽  
Basolateral Membrane ◽  
Drug Efflux ◽  
Drug Transfer ◽  
P Glycoprotein ◽  
Drug Efflux Pump ◽  
Apical Membranes

P-glycoprotein (P-gp) on the apical membranes of epithelial cells is known as a drug efflux pump. However, unclear is its integral quantitative role in the overall epithelial drug transfer, which also involves distinct diffusion processes in parallel and sequence. We used a simple three-compartment model to obtain kinetic parameters of each drug transfer mechanism, which can quantitatively describe the transport time courses of P-gp substrates, digoxin and vinblastine, across P-gp-expressing MDCK cell monolayers grown on permeable filters. Our results show that the model, which assumes a functionally single drug efflux pump in the apical membrane with diffusion across two membranes and intercellular junctions, is the least complex model with which to quantitatively reproduce the characteristics of the data. Interestingly, the model predicts that the MDCK apical membranes are less diffusion permeable than the basolateral membrane for both drugs and that the distribution volume of vinblastine is 10-fold higher than that of digoxin. Additional experiments verified these model predictions. The modeling approach is feasible to quantitatively describe overall kinetic picture of epithelial drug transport. Further model refinement is necessary to incorporate other modes of drug transport such as transcytosis. Also, whether P-gp solely accounts for the pump function in this model awaits more studies.

Glutathione 5-transferase and P-glycoprotein in multidrug resistant chinese hamster cells

1990 ◽  
Vol 39 (11) ◽  
pp. 1641-1645 ◽  
Author(s):  
Rheem D. Medh ◽  
Vicram Gupta ◽  
Yin Zhang ◽  
Yogesh C. Awasthi ◽  
James A. Belli
Keyword(s):  
Chinese Hamster ◽  
Multidrug Resistant ◽  
Chinese Hamster Cells ◽  
P Glycoprotein

scholarly journals A possible role for a mammalian facilitative hexose transporter in the development of resistance to drugs

1991 ◽  
Vol 11 (7) ◽  
pp. 3407-3418
Author(s):  
J C Vera ◽  
G R Castillo ◽  
O M Rosen
Keyword(s):  
Xenopus Oocytes ◽  
Glucose Transporter ◽  
Cytochalasin B ◽  
Chinese Hamster ◽  
Multidrug Resistant ◽  
Xenopus Laevis Oocytes ◽  
Hexose Transporter ◽  
P Glycoprotein ◽  
Glut1 Protein ◽  
Facilitative Glucose Transporter

We show that D- but not L-hexoses modulate the accumulation of radioactive vinblastine in injected Xenopus laevis oocytes expressing the murine Mdr1b P-glycoprotein. We also show that X. laevis oocytes injected with RNA encoding the rat erythroid/brain glucose transport protein (GLUT1) and expressing the corresponding functional transporter exhibit a lower accumulation of [3H]vinblastine and show a greater capacity to extrude the drug than do control oocytes not expressing the rat GLUT1 protein. Cytochalasin B and phloretin, two inhibitors of the mammalian facilitative glucose transporters, can overcome the reduced drug accumulation conferred by expression of the rat GLUT1 protein in Xenopus oocytes but have no significant effect on the accumulation of drug by Xenopus oocytes expressing the mouse Mdr1b P-glycoprotein. These drugs also increase the accumulation of [3H]vinblastine in multidrug-resistant Chinese hamster ovary cells. Cytochalasin E, an analog of cytochalasin B that does not affect the activity of the facilitative glucose transporter, has no effect on the accumulation of vinblastine by multidrug-resistant Chinese hamster cells or by oocytes expressing either the mouse Mdr1b P-glycoprotein or the GLUT1 protein. In all three cases, the drug verapamil produces a profound effect on the cellular accumulation of vinblastine. Interestingly, although immunological analysis indicated the presence of massive amounts of P-glycoprotein in the multidrug-resistant cells, immunological and functional studies revealed only a minor increase in the expression of a hexose transporter-like protein in resistant versus drug-sensitive cells. Taken together, these results suggest the participation of the mammalian facilitative glucose transporter in the development of drug resistance.

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