Table 1

Sensitization of MDR cell lines to doxorubicin by XR9576, GG918, and PSC 833a

Drug-sensitive cells
Doxorubicin IC50 (nm)
With no modulator30.545.213
With XR9576 100 nm549.611
Drug-resistant cells
Doxorubicin IC50 (nm)
With no modulator101935.8972927.4
With XR9576
3 nm59825.6523.61040
10 nm24.717.5117.473
30 nm7.17.743.820
50 nm7.47.242.414
100 nm6.86.743.113
With GG918
3 nm484.2NDb282.1647
10 nm3829.6116.551
30 nm9.21745.518
50 nm7.810.443.414
100 nm7.17.643.114
With PSC 833
50 nm89.225.4444.3678
100 nm40.220.4233.8627
300 nm30.58.35858
500 nm287.936.828
1000 nm26.9ND41.113c
  • aThe values represent results from a single potentiation assay performed in quadruplicate wells as described in “Materials and Methods” and is representative of at least three separate experiments.

  • b ND, not done.

  • c Toxic, modulator alone inhibited cell growth by >10% of control value.