Abstract

This proposal represents an attempt to study the molecular basis of altered drug accumulation in cells overexpressing the P- glycoprotein (pGP). This proposal is aimed at evaluating the kinetic differences in drug translocation in cells expressing different levels of pGP generated either by selection in cytotoxic agents or co- selection in G418. Drug translocation will be monitored using fluorescent substrates (doxorubicin, coumarin-vinblastine, COL-FITC) by continuous monitoring of fluorescence. The studies will determine the importance of pHi and the electrical plasma membrane potential in the role of drug translocation and the role of pGP in the generation of these physiological parameters. These parameters will be characterized in cell lines expressing different amounts of pGP. pHi will be modulated by incubation in at different levels of C02 and extracellular HCO3 and membrane potential with ouabain and tri-ethyl-ammonium.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
7R01GM054516-03
Application #
2546037
Study Section
Experimental Therapeutics Subcommittee 1 (ET)
Project Start
1995-09-30
Project End
1999-09-29
Budget Start
1997-09-30
Budget End
1999-09-29
Support Year
3
Fiscal Year
1997
Total Cost
Indirect Cost

  Institution

Name
Georgetown University
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
049515844
City
Washington
State
DC
Country
United States
Zip Code
20057

  Publications

Fritz, F; Howard, E M; Hoffman, M M et al. (1999) Evidence for altered ion transport in Saccharomyces cerevisiae overexpressing human MDR 1 protein. Biochemistry 38:4214-26
Weisburg, J H; Roepe, P D; Dzekunov, S et al. (1999) Intracellular pH and multidrug resistance regulate complement-mediated cytotoxicity of nucleated human cells. J Biol Chem 274:10877-88
Santai, C T; Fritz, F; Roepe, P D (1999) Effects of ion gradients on H+ transport mediated by human MDR 1 protein. Biochemistry 38:4227-34
Roepe, P D; Martiney, J A (1999) Are ion-exchange processes central to understanding drug-resistance phenomena? Trends Pharmacol Sci 20:62-5
Robinson, L J; Roberts, W K; Ling, T T et al. (1997) Human MDR 1 protein overexpression delays the apoptotic cascade in Chinese hamster ovary fibroblasts. Biochemistry 36:11169-78
Wei, L Y; Hoffman, M M; Roepe, P D (1997) Altered pHi regulation in 3T3/CFTR clones and their chemotherapeutic drug-selected derivatives. Am J Physiol 272:C1642-53
Wadkins, R M; Roepe, P D (1997) Biophysical aspects of P-glycoprotein-mediated multidrug resistance. Int Rev Cytol 171:121-65
Hoffman, M M; Roepe, P D (1997) Analysis of ion transport perturbations caused by hu MDR 1 protein overexpression. Biochemistry 36:11153-68
Hoffman, M M; Wei, L Y; Roepe, P D (1996) Are altered pHi and membrane potential in hu MDR 1 transfectants sufficient to cause MDR protein-mediated multidrug resistance? J Gen Physiol 108:295-313
Roepe, P D; Wei, L Y; Hoffman, M M et al. (1996) Altered drug translocation mediated by the MDR protein: direct, indirect, or both? J Bioenerg Biomembr 28:541-55

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