The multidrug resistance observed in tumor cells is often associated with the expression of two membrane proteins, the P-glycoprotein (Pgp) and the multidrug resistance associated protein (MRP). These proteins function as ATP-driven efflux pumps for large lipophilic molecules. The separation of P-glycoprotein and MRP expressing cells in clinical samples would be an important tool for proper diagnosis and the development of new therapeutical strategies. Calcein-AM is efficiently exported both by Pglycoprotein and MRP, thus by using selective inhibitory agents for MRPdependent calcein-AM extrusion, we can functionally separate cells expressing Pgp or MRP. By applying the calcein-AM extrusion assay we demonstrate in different drug resistant cell lines the functional separation of P-glycoprotein and MRP expressing cells by single cell fluorescence imaging. In the same single cell apparatus the functional distinction of the two multidrug transporters is reinforced by TRITC-conjugated anti-Pgp antibody labeling experiments. The results obtained by the combination of these two methods gives us the possibility to examine the functional characteristics of P-glycoprotein and MRP in single cell experiments.
|Publication status||Published - Dec 1 1997|
ASJC Scopus subject areas
- Molecular Biology