Drug resistance profiles of HEK cells expressing wild-type BCRP and its variants Relative resistance factors (RR) were obtained by dividing the IC50 values of cells expressing wild-type BCRP (482R) or its variants by the IC50 values of the vector control cells. The ratios represent the relative levels of resistance of the variants as compared with wild-type BCRP after normalization for differences in BCRP expression. The relative BCRP expression levels shown in Fig. 1B were used for these calculations. Since wild-type BCRP and the variants did not confer resistance to daunorubicin and rhodamine 123, the ratios for daunorubicin and rhodamine 123 were not calculated. The IC50 values shown are means ± S.D. of at least three independent experiments.
MX | Topotecan | Daunorubicin | Rhodamine 123 | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| IC50 | RR | Ratio | IC50 | RR | Ratio | IC50 | RR | IC50 | RR | |||||||
| nM | nM | nM | nM | |||||||||||||
| pcDNA | 32.5 ± 3.1 | 8.5 ± 1.0 | 34.2 ± 4.1 | 5797.9 ± 1209.4 | ||||||||||||
| 482R-21 | 226.3 ± 27.4 | 7.0 | 1.0 | 122.8 ± 23.3 | 14.4 | 1.0 | 40.0 ± 1.7 | 1.2 | 10281.0 ± 1445.4 | 1.7 | ||||||
| I206L-13 | 209.7 ± 19.5 | 6.5 | 2.06 | 124.9 ± 17.1 | 14.7 | 2.25 | 25.6 ± 2.8 | 0.7 | 8829.4 ± 1454.8 | 1.5 | ||||||
| N590Y-1 | 287.9 ± 24.0* | 8.9 | 0.35 | 130.5 ± 17.8 | 15.4 | 0.30 | 19.9 ± 2.3 | 0.6 | 7867.9 ± 3691.1 | 1.3 | ||||||
| D620N-9 | 271.9 ± 33.3* | 8.4 | 0.48 | 278.3 ± 18.9* | 32.7 | 0.91 | 31.6 ± 1.8 | 0.9 | 15469.3 ± 1762.5 | 2.6 | ||||||
↵* Indicates that the un-normalized IC50 values of the 482R cells are significantly different (p < 0.05) from the N590Y or D620N cells as calcualted by Student's t test