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Updated: Jun 27, 2025
Expression, Detergent Solubilization, and Purification of a Membrane Transporter, the MexB Multidrug Resistance Protein
Published on: December 3, 2010
Membrane-Fusing Vehicles for Re-Sensitizing Transporter-Mediated Multiple-Drug Resistance in Cancer
Sahel Vahdati1,2, Alf Lamprecht1
1Departments of Pharmaceutics, Institute of Pharmacy, University of Bonn, 53121 Bonn, Germany.
Abstract:
Reversing the multiple drug resistance (MDR) arising from the overexpression of the efflux transporters often fails mainly due to the high toxicity or the poor water solubility of the inhibitors of these transporters. Here, we demonstrate the delivery of an inhibitor targeting three ABC transporters (ABCB1, ABCC1 and ABCG2) directly to the cell membrane using membrane-fusing vehicles (MFVs). Three different transfected MDCK II cell lines, along with parental cells, were used to investigate the inhibitory effect of cyclosporine A (CsA) in solution versus direct delivery to the cell membrane. CsA-loaded MFVs successfully reversed MDR for all three investigated efflux transporters at significantly lower concentrations compared with CsA in solution. Results showed a 15-fold decrease in the IC50 value for ABCB1, a 7-fold decrease for ABCC1 and an 11-fold decrease for ABCG2. We observed binding site specificity for ABCB1 and ABCG2 transporters. Lower concentrations of empty MFVs along with CsA contribute to the inhibition of Hoechst 33342 efflux. However, higher concentrations of CsA along with the high amount of MFVs activated transport via the H-binding site. This supports the conclusion that MFVs can be useful beyond their role as delivery systems and also help to elucidate differences between these transporters and their binding sites.
Insights
Membrane-fusing vehicles (MFVs) effectively deliver cyclosporine A (CsA) to reverse multidrug resistance (MDR) mediated by ABC transporters. This targeted delivery uses lower concentrations and reveals transporter binding site differences.
Area of Science:
- Biochemistry
- Cell Biology
- Pharmacology
Background:
- Multidrug resistance (MDR) poses a significant challenge in medicine, often stemming from the overexpression of ATP-binding cassette (ABC) transporters.
- Current inhibitors of these efflux transporters frequently exhibit high toxicity or poor water solubility, limiting their therapeutic efficacy.
- Developing effective strategies to overcome MDR requires novel drug delivery systems that can enhance inhibitor potency and reduce side effects.
Purpose of the Study:
- To investigate the efficacy of delivering cyclosporine A (CsA), an inhibitor of ABCB1, ABCC1, and ABCG2 transporters, directly to the cell membrane using membrane-fusing vehicles (MFVs).
- To compare the MDR-reversing capabilities of CsA delivered via MFVs versus CsA in solution.
- To explore the potential of MFVs in elucidating transporter binding site specificities.
Main Methods:
- Utilized three transfected MDCK II cell lines overexpressing ABCB1, ABCC1, and ABCG2, alongside parental cells.
- Administered CsA loaded into MFVs directly to the cell membrane.
- Compared the inhibitory concentrations (IC50) of CsA in solution versus MFVs for reversing MDR.
- Investigated the effect of MFVs and CsA concentrations on Hoechst 33342 efflux.
Main Results:
- CsA-loaded MFVs significantly reversed MDR mediated by all three tested ABC transporters at lower concentrations compared to CsA in solution.
- Observed substantial reductions in IC50 values: 15-fold for ABCB1, 7-fold for ABCC1, and 11-fold for ABCG2.
- Demonstrated binding site specificity for ABCB1 and ABCG2 transporters.
- Identified that MFVs, beyond drug delivery, can modulate transporter activity and help differentiate binding sites.
Conclusions:
- MFVs provide an effective delivery system for CsA, overcoming limitations of traditional administration and significantly enhancing its MDR-reversing potential.
- The MFV delivery system allows for the use of lower, less toxic concentrations of CsA.
- This approach offers insights into the distinct binding characteristics of ABC transporters, particularly ABCB1 and ABCG2.
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