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Expression, Detergent Solubilization, and Purification of a Membrane Transporter, the MexB Multidrug Resistance Protein
Published on: December 3, 2010
Multidrug resistance: a role for cholesterol efflux pathways?
1Dept of Biological Regulation, Weizmann Institute of Science, 76100, Rehovot, Israel. moti.liscovitch@weizmann.ac.il
Abstract:
Multidrug resistance (MDR) severely impairs the efficacy of cancer chemotherapy. Several protein transporters that mediate drug export have been identified, but additional adaptations appear to be necessary for full-fledged drug resistance. The cell surface density of caveolae and the expression of the caveolar coat protein caveolin are dramatically increased in MDR cancer cells. Acquisition of MDR might thus be accompanied by upregulation of caveolin-dependent cholesterol efflux pathways, raising the possibility that these same pathways are utilized for delivering drugs from intracellular compartments to the plasma membrane, where drugs can be extruded from the cells by drug efflux ATPases. The upregulation of caveolin mandates a phenotypic change of MDR cells in terms of their cholesterol homeostasis and is accompanied by loss of important features of the transformed phenotype of MDR cancer cells.
Insights
Multidrug resistance (MDR) in cancer cells involves increased caveolin and caveolae, potentially aiding drug export. This adaptation alters cholesterol homeostasis and reduces cancer cell transformation features.
Area of Science:
- Biochemistry
- Cell Biology
- Cancer Research
Background:
- Multidrug resistance (MDR) significantly reduces chemotherapy effectiveness in cancer treatment.
- While drug efflux transporters are known, other cellular adaptations are crucial for MDR.
- Increased cell surface caveolae and caveolin expression are observed in MDR cancer cells.
Purpose of the Study:
- To investigate the role of caveolin and caveolae in multidrug resistance.
- To explore the connection between caveolin-dependent cholesterol efflux and drug transport in MDR cells.
- To understand how caveolin upregulation impacts the phenotype and cholesterol homeostasis of MDR cancer cells.
Main Methods:
- Analysis of caveolae and caveolin expression in multidrug-resistant cancer cells.
- Investigation of cholesterol efflux pathways in relation to MDR.
- Assessment of phenotypic changes and cholesterol homeostasis in MDR cells with altered caveolin levels.
Main Results:
- Multidrug-resistant cancer cells exhibit dramatically increased cell surface caveolae and caveolin expression.
- Upregulation of caveolin correlates with enhanced caveolin-dependent cholesterol efflux pathways.
- These pathways may facilitate intracellular drug transport to the plasma membrane for extrusion by efflux ATPases.
- Caveolin upregulation leads to altered cholesterol homeostasis and a loss of transformed cell phenotype in MDR cells.
Conclusions:
- Caveolin and caveolae play a significant role in the development of multidrug resistance in cancer.
- Caveolin-mediated cholesterol transport pathways are implicated in the mechanism of drug extrusion.
- Targeting caveolin or associated pathways may offer novel strategies to overcome MDR and re-sensitize cancer cells to chemotherapy.
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