Table 3

Resistance to antitumor drugs conferred by human MRP2 in transfected HEK-293 cells

DrugHEK-Co CellsHEK-MRP2 Cells
Etoposide (μM)0.3  ± 0.11.2  ± 0.54.03-b
Cisplatin (μM)2.4  ± 0.624.2  ± 4.410.03-b
Doxorubicin (nM)44.3  ± 0.3346.3  ± 48.17.83-b
Epirubicin (nM)3.8  ± 1.518.8  ± 2.05.03-b

Sensitivity to drugs was determined using MTT cell viability assays as described in Experimental Procedures. All values were obtained in the presence of MDR1 P-glycoprotein inhibitor LY335979 (0.25 μM). Trichostatin A was omitted in this experiment. Data represent the mean ± S.D. (n ≥ 6). The significance of relative resistance factors (RR) was calculated by Student’st test.

  • 3-a The relative resistance factor (RR) was calculated by dividing the IC50 value of cells transfected with MRP2 expression vector (HEK-MRP2) by the IC50 value of cells transfected with the control vector (HEK-Co).

  • 3-b P ≤ .01 compared to HEK-Co.