Résumé
This study was aimed to investigate the reversible effect of cyclosporine A, raloxifene and their combination on multidrug resistance cell line K562/A02. The IC(50) (the concentration causing 50% inhibition of cell growth) of DNR were assayed by MTT method, the expression level of mdr-1 mRNA was assayed by RT-PCR, p-glycoprotein (P-gp) expression and intracellular DNR concentration were detected by flow cytometry. The results showed that the IC(50) of DNR on K562/A02 and K562 cells were 23.51 mg/L and 0.29 mg/L, respectively. The IC(50) of DNR on K562/A02 cells in treatment with raloxifene CsA and both combination were 5.98, 8.15 and 3.68 mg/L respectively, but both drugs not influenced IC(50) of DNR on K562 cells. Pretreating K562/A02 cells with raloxifene (2.5 mg/L) or CsA (1 mg/L) for 48 hours partially restored the sensitivity of K562/A02 cells to DNR. Cyclosporine A and raloxifene (alone or combination) elevated the intracellular DNR concentration in K562/A02, down regulated P-gp and mdr-1 mRNA expressions. It is concluded that multidrug resistance (MDR) can be partially reversed by CsA or raloxifene, the combination of both drugs shows a great synergistic reversal effect.