Figure 7

The mdr phenotype of MCF-7/Adr cells and its reversion with hydralazine and verapamil. a) Untreated MCF-7/Adr cells had no intracellular retention of adriamycin as indicated by MI, whereas verapamil and hydralazine clearly led to drug retention, and b) hydralazine decreased mdr1 gene expression as evaluated by RT-PCR. Figure 7c demonstrates that pre-treatment with verapamil led to only a 50% decrease in viability when cells were exposed to adriamycin as compared with an 85% reduction achieved with hydralazine pre-treatment.