American Society of Hematology

Figure 1

$Coadministration of dasatinib and MEK1/2 inhibitors markedly increases apoptosis in Bcr/Abl+ human leukemia cells and CML CD34+ cells. (A) K562 cells were exposed to 5 μM PD184352 (PD) and 0.6 nM dasatinib (Das) alone or in combination for 48 hours, after which the percentage of apoptotic cells was determined by annexin-V/PI analysis as described in “Materials and methods.” (B) K562 cells were exposed for 48 hours to the designated concentration of dasatinib alone or in conjunction with 5 μM PD, after which the percentage of apoptotic cells was determined. (C) K562 cells were exposed to the designated concentration of PD alone or in combination with 0.6 nM dasatinib for 48 hours, after which apoptosis was determined. (D) K562 cells were treated with PD184352 (5 μM) or dasatinib (0.6 nM) individually or in combination for the indicated intervals, after which the extent of cell death was determined. (E) K562 cells were exposed to varying concentrations of PD184352 and dasatinib at a fixed ratio; then combination index (CI) values were determined in relation to the fractional effect using a commercially available software program as described in “Materials and methods.” Combination index values less than 1.0 correspond to a synergistic interaction. (F) K562 cells were exposed to the MEK1/2 inhibitor U0126 (20 μM) and dasatinib (0.6 nM) alone or in combination for 48 hours, after which the percentage of apoptosis was determined. (G) LAMA-84 cells were exposed to 1 μM PD and 0.5 nM dasatinib alone or in combination for 48 hours, after which the percentage of apoptotic cells was determined. CI value was determined in LAMA-84 cells as the cells were exposed to varying concentrations of PD and dasatinib (inset). All values represent the means ± SD for duplicate determinations performed on 3 separate occasions. In all cases, apoptosis was determined by annexin-V/PI staining and flow cytometry. (H) CD34+ cells isolated from the bone marrow of a patient with chronic-phase CML and a patient with a nonmyeloid hematologic disorder (iron deficiency) were exposed to PD184352 (2.5 μM) with or without dasatinib (1 nM) alone and in combination for 48 hours. At the end of this period, the percentage of apoptotic cells was determined by annexin-V/PE.$

Coadministration of dasatinib and MEK1/2 inhibitors markedly increases apoptosis in Bcr/Abl⁺ human leukemia cells and CML CD34⁺ cells. (A) K562 cells were exposed to 5 μM PD184352 (PD) and 0.6 nM dasatinib (Das) alone or in combination for 48 hours, after which the percentage of apoptotic cells was determined by annexin-V/PI analysis as described in “Materials and methods.” (B) K562 cells were exposed for 48 hours to the designated concentration of dasatinib alone or in conjunction with 5 μM PD, after which the percentage of apoptotic cells was determined. (C) K562 cells were exposed to the designated concentration of PD alone or in combination with 0.6 nM dasatinib for 48 hours, after which apoptosis was determined. (D) K562 cells were treated with PD184352 (5 μM) or dasatinib (0.6 nM) individually or in combination for the indicated intervals, after which the extent of cell death was determined. (E) K562 cells were exposed to varying concentrations of PD184352 and dasatinib at a fixed ratio; then combination index (CI) values were determined in relation to the fractional effect using a commercially available software program as described in “Materials and methods.” Combination index values less than 1.0 correspond to a synergistic interaction. (F) K562 cells were exposed to the MEK1/2 inhibitor U0126 (20 μM) and dasatinib (0.6 nM) alone or in combination for 48 hours, after which the percentage of apoptosis was determined. (G) LAMA-84 cells were exposed to 1 μM PD and 0.5 nM dasatinib alone or in combination for 48 hours, after which the percentage of apoptotic cells was determined. CI value was determined in LAMA-84 cells as the cells were exposed to varying concentrations of PD and dasatinib (inset). All values represent the means ± SD for duplicate determinations performed on 3 separate occasions. In all cases, apoptosis was determined by annexin-V/PI staining and flow cytometry. (H) CD34⁺ cells isolated from the bone marrow of a patient with chronic-phase CML and a patient with a nonmyeloid hematologic disorder (iron deficiency) were exposed to PD184352 (2.5 μM) with or without dasatinib (1 nM) alone and in combination for 48 hours. At the end of this period, the percentage of apoptotic cells was determined by annexin-V/PE.

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