A. Didier et al., DETECTION OF P-GLYCOPROTEIN EXPRESSION BY TUMORAL CELLS WITH NBDL-CSA, A FLUORESCENT DERIVATIVE OF CYCLOSPORINE-A, Anti-cancer drugs, 7(3), 1996, pp. 257-265
The P-glycoprotein (P-gp) molecules which expressed on multidrug-resis
tant (MDR) tumor efflux a variety of anti-cancer drugs, such as doxoru
bicin, Though first described as an inhibitor of P-gp function, cyclos
porin A (CsA) was more recently shown to behave as a substrate of the
P-gp pump, The retention of [H-3]CsA was reduced in MDR cells of the h
uman leukemic GEM cell subline, in comparison with the drug-sensitive
parental (Par) subline, MDR-GEM cell treatment by the P-gp blockers re
stored the [H-3]CsA retention to the control Par-GEM cell levels, Usin
g a novel fluorescent GsA derivative, [N-epsilon-(4-nitrobenzofurazan-
7-yl)-D-Lys(8)] cyclosporin (NBDL-CsA), we now show that MDR cells can
be distinguished from Par cells both at the cell population level (in
microculture) and at the single cell level (by use of flow cytometry)
.