Document Detail

Inhibition of the MRP1-mediated transport of the menadione-glutathione conjugate (thiodione) in HeLa cells as studied by SECM.
MedLine Citation:
PMID:  22679290     Owner:  NLM     Status:  MEDLINE    
Oxidative stress induced in live HeLa cells by menadione (2-methyl-1,4-napthaquinone) was studied in real time by scanning electrochemical microscopy (SECM). The hydrophobic molecule menadione diffuses through a living cell membrane where it is toxic to the cell. However, in the cell it is conjugated with glutathione to form thiodione. Thiodione is then recognized and transported across the cell membrane via the ATP-driven MRP1 pump. In the extracellular environment, thiodione was detected by the SECM tip at levels of 140, 70, and 35 µM upon exposure of the cells to menadione concentrations of 500, 250, and 125 µM, respectively. With the aid of finite element modeling, the kinetics of thiodione transport was determined to be 1.6 10(-7) m/s, about 10 times faster than menadione uptake. Selective inhibition of these MRP1 pumps inside live HeLa cells by MK571 produced a lower thiodione concentration of 50 µM in presence of 500 µM menadione and 50 µM MK571. A similar reduced (50% drop) thiodione efflux was observed in the presence of monoclonal antibody QCRL-4, a selective blocking agent of the MRP1 pumps. The reduced thiodione flux confirmed that thiodione was transported by MRP1, and that glutathione is an essential substrate for MRP1-mediated transport. This finding demonstrates the usefulness of SECM in quantitative studies of MRP1 inhibitors and suggests that monoclonal antibodies can be a useful tool in inhibiting the transport of these MDR pumps, and thereby aiding in overcoming multidrug resistance.
Dipankar Koley; Allen J Bard
Publication Detail:
Type:  Journal Article     Date:  2012-06-07
Journal Detail:
Title:  Proceedings of the National Academy of Sciences of the United States of America     Volume:  109     ISSN:  1091-6490     ISO Abbreviation:  Proc. Natl. Acad. Sci. U.S.A.     Publication Date:  2012 Jul 
Date Detail:
Created Date:  2012-07-18     Completed Date:  2012-10-11     Revised Date:  2013-07-12    
Medline Journal Info:
Nlm Unique ID:  7505876     Medline TA:  Proc Natl Acad Sci U S A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  11522-7     Citation Subset:  IM    
Center for Electrochemistry, Department of Chemistry and Biochemistry, University of Texas at Austin, 1 University Station A5300, Austin, TX 78712-0165, USA.
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MeSH Terms
Antibodies, Monoclonal / pharmacology
Biological Transport / drug effects,  physiology
Electrochemical Techniques
Finite Element Analysis
Glutathione / analogs & derivatives*,  metabolism
HeLa Cells
Microscopy, Scanning Probe / methods*
Molecular Dynamics Simulation
Molecular Structure
Multidrug Resistance-Associated Proteins / metabolism,  pharmacology*
Oxidative Stress / physiology*
Propionates / pharmacology
Quinolines / pharmacology
Vitamin K 3 / analogs & derivatives*,  metabolism
Reg. No./Substance:
0/Antibodies, Monoclonal; 0/Multidrug Resistance-Associated Proteins; 0/Propionates; 0/Quinolines; 0/menadione-S-glutathione conjugate; 0/multidrug resistance-associated protein 1; 115104-28-4/verlukast; 58-27-5/Vitamin K 3; 70-18-8/Glutathione

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