DESCRIPTION: Multidrug Resistance
P-glycoprotein (P-gp), the product of the multidrug resistance (MDR)-1 gene acts as a unidirecitonal efflux pump in the membrane of AML cells and lowers the intracellular concentration of cytotoxic agents by pumping them out of leukemic cells. Therefore, P-gp confers resistance to a variety of chemotherapy drugs, including daunorubicin. On the contrary, in vitro data suggest that the intracellular accumulation of idarubicin is less affected by P-gp.[6,7]
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| The pumping activity of P-gp can be demonstrated through flow cytometry by monitoring the efflux of rhodamine 123 from AML blasts (labeled with stem cell CD34 antigen) over 60 minutes. Functional P-gp is present if a significant fraction of blasts become rhodamine negative or dull during this time period. |
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| The presence of P-gp can be documented by antibody staining as shown in the histogram in comparison to the control cell population[4,6] |
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