TABLE 1

Interactions of steroid drugs and some endogenous steroid hormones with BCRP-mediated transport of mitoxantrone

MEF3.8-BCRP and its parental subline were preincubated with a test compound for 1 h, then 10 μM mitoxantrone was applied to the medium, accumulation was allowed for 1 h, and cells were subsequently evaluated by flow cytometry. Data are expressed as a mean ± S.D. from at least three experiments.


Test Compound

Concentration

Inhibitory Potency
μM %#
Beclomethasone## 20 40.4 ± 3.2**
6α-methylprednisolone 50 21.5 ± 2.2**
Corticosterone 50 20.7 ± 4.0*
Triamcinolone 50 15.3 ± 4.3*
Dexamethasone 50 13.2 ± 2.4**
Betamethasone 50 10.9 ± 3.5*
Prednisone 50 7.4 ± 1.6*
Dexamethasone-21-phosphate 50 0.5 ± 1.5
Hydrocortisone 50 -0.4 ± 1.8
Prednisolone 50 -2.9 ± 1.6
Aldosterone 50 -3.2 ± 5.0
Digoxin 50 45.1 ± 1.7**
Ursodeoxycholic acid 50 2.8 ± 4.3
Ko143
1
100
  • # Inhibitory potency of tested compounds was related to the effect of reference inhibitor Ko143 at a concentration of 1 μM (set at 100% inhibition of BCRP).

  • ## The solubility limit of beclomethasone in medium is 20 μM.

  • * p < 0.05; **p < 0.01