[Reversal of multidrug resistance by lomerizine in K562/ADM cells]

Aim: To study the effect of lomerizine (Lom) on the reversal of multidrug resistance (MDR) in K562/ADM cells and its mechanism.

Methods: MTT assay was used to determine the influence of Lom on the cytotoxicity of adriamycin (ADM). The effect of Lom on the Apoptosis induced by ADM and vincristine (VCR) in K562/ADM cells was detected using flow cytometry. Intracellular accumulation of ADM was measured by fluorescence spectrophotometry. Flow cytometry was used to investigate the efflux of rhodamine 123 (Rh123) and the expression of P-glycoprotein (P-gp) in K562/ADM cells.

Results: Lom increased the cytotoxicity of ADM and the Apoptosis induced by ADM or VCR in K562/ADM cells. At the concentration of 3, 10 and 30 micromol x L(-1), Lom reduced the IC50 value of ADM from 79.03 micromol x L(-1) to 28.14, 8.16 and 3.16 micromol x L(-1), respectively. Lom increased the intracellular accumulation of ADM and inhibited the efflux of Rh123 in K562/ ADM cells. No change in P-gp expression was observed after the treatment of Lom for 72 h.

Conclusion: Lom had strong reversal effect on MDR in K562/ADM cells by inhibiting P-gp function.