Table 1

Resistance of transfected HEK 293 cells to chemotherapeutic agents

DrugIC501-aResistance factor
HEKPC7HEKmrpHEKMRPHEKmrpHEKMRP
Vincristine1.87  ± 0.8117.03  ± 6.071-a , 1-b 46.30  ± 8.781-a , 1-b 9.124.8
(n = 3)(n = 3)(n = 3)
Vinblastine2.23  ± 1.01-b 5.12  ± 2.131-b 11.49  ± 8.931-b 2.35.2
(n = 3)(n = 3)(n = 3)
VP-161.62  ± 0.866.24  ± 2.261-a 22.10  ± 12.701-a 4.014.0
(n = 4)(n = 4)(n = 4)
Doxorubicin0.128  ± 0.0730.062  ± 0.0211.21  ± 0.661-a <19.4
(n = 3)(n = 3)(n = 3)
Daunorubicin0.061  ± 0.0100.037  ± 0.0090.326  ± 0.1081-a <15.3
(n = 3)(n = 3)(n = 3)
Epirubicin0.076  ± 0.0390.035  ± 0.0110.674  ± 0.1881-a <18.9
(n = 4)(n = 4)(n = 4)
Colchicine0.0880.0640.235<12.7
(0.064, 0.111)(0.058, 0.070)(0.092, 0.378)
Cisplatin8.02  ± 0.744.09  ± 0.921-a 5.10  ± 2.33<1<1
(n = 3)(n = 3)(n = 3)
Novobiocin266.08  ± 22.57302.87  ± 19.14389.40  ± 7.711-a 1.11.5
(n = 3)(n = 3)(n = 3)

The IC50 values were determined using the 3-(4,5-dimethylthiazol-z-yl)-2,5-diphenyltetrazolium assay and are expressed as μm concentrations unless otherwise indicated. Values are mean ± standard deviation of three or four independent experiments. When fewer than three experiments were performed, the IC50 values of the individual experiments are given in parentheses. When three or more independent experiments were carried out, statistical significance was determined using an unpaired t test. The resistance factors are expressed as the ratio of the IC50 value of HEK 293 cells transfected with human (HEKMRP) or murine (HEKmrp) MRP expression vectors relative to cells transfected with vector alone (HEKPC7).

    • 1-a Values obtained with the resistant cell populations, HEKMRP and HEKmrp, are significantly different from those obtained with sensitive cells HEKPC7 (p ≤ 0.05).

    • 1-b Values are given in nm.