A rapid and sensitive flow cytometric method for the detection of multidrug-resistant cells.
Multidrug-resistant (MDR) cells are characterized by a defect in drug accumulation caused by activity of an energy-dependent rapid drug efflux pump. The action of this drug pump can be inhibited by specific agents, referred to as membrane transport modulating agents (MTMAs), resulting in a restoration of the intracellular drug accumulation. This paper presents a flow cytometric assay for the detection of MDR cells, which is based on the ability of these cells to respond to MTMAs. Daunorubicin net-uptake kinetics were measured of anthracycline-sensitive (A2780/S) and -resistant (A2780/R) human ovarian carcinoma cells in vitro. A2780/R cells accumulated significantly less (about a factor of 5) daunorubicin as compared to A2780/S cells. Addition of verapamil or cyclosporin A to A2780/R cells at steady-state daunorubicin uptake led to a dose-dependent increase in cellular daunorubicin accumulation. The sensitivity of the assay was determined by testing mixtures of A2780/S and A2780/R cells. Analysis of A2780/S cells contaminated with A2780/R cells showed that as few as 2.5% MDR cells could readily be detected in the mixture. In conclusion, this functional assay enables the detection of MDR cells in a heterogeneous cell suspension and is ideally suited for the study of the occurrence of typical MDR in human cancer.
Daniel den Hoed Cancer Center, Rotterdam, The Netherlands.
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H
Herweijer
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G
van den Engh
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K
Nooter
D000903:Antibiotics, Antineoplastic / Q000494:pharmacology* / Q000627:therapeutic use; D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D002277:Carcinoma; D002460:Cell Line; D004352:Drug Resistance, Microbial; D004354:Drug Screening Assays, Antitumor / Q000379:methods*; D005260:Female; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D010051:Ovarian Neoplasms; D014407:Tumor Cells, Cultured / Q000032:analysis* / Q000187:drug effects
D000903:Antibiotics, Antineoplastic; D000970:Antineoplastic Agents