calcein-am and 6-carboxyfluorescein

MRP1 activity was evaluated and compared in 11 cell lines with different levels of MRP1 expression using functional assays of calcein acetoxymethyl ester (calcein-AM), carboxyfluorescein diacetate (CFDA) and Rhodamine 123 (Rh123) in combination with the modulators cyclosporin A (CsA), probenecid and MK571. A good correlation was found between MRP1 expression and the modulatory effect of MK571 on calcein-AM uptake (P = 0.01 and probenecid effect on CFDA uptake (P = 0.02). Additionally, the combined modulatory effect of MK571 and probenecid on CFDA uptake (P < 0.0001) and on calcein-AM uptake (P = 0.0001) were highly significant. No correlation was found between MRP1 expression and the effects of three modulators on Rh123 uptake or efflux. In conclusion, calcein-AM and CFDA uptake assays are the best choices to probe MRP1 activity and combination of two modulators may improve the efficiency of these assays.

Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Biological Transport; Bronchodilator Agents; Cyclosporine; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Enzyme Inhibitors; Fluoresceins; Fluorescent Dyes; Humans; Leukemia; Multidrug Resistance-Associated Proteins; Probenecid; Propionates; Quinolines; Rhodamine 123; Tumor Cells, Cultured