The relative expression of the drug-efflux pumps P-gp, MRP, LRP, and BCRP was evaluated by mean fluorescence index (MFI) and the Kolmogorov-Smirnov analysis (D values) in five leukemic subpopulations: CD34+CD38-CD123+ (LSCs), CD34+CD38+CD123-, CD34+CD38+CD123+, CD34+CD38+CD123-, and CD34- mature cells in 26 bone marrow samples of CD34+ AML cases.
Presence of BCRP only in subpopulations and discordance among BCRP measurements suggest complex biology of BCRP in AML and incomplete modeling by cell lines.
At diagnosis BCRP activity was undetectable in AML blasts from 23/26 cases, while Pgp activity was present in 36/45 and MRP activity in 26/44 of the cases.
Recently, the breast cancer-resistant protein (BCRP), the equivalent of mitoxantrone-resistant protein (MXR) or placental ABC transporter (ABCP), was described in AML.