Objective: To study the influence of selenium chiston (SC) on mdr-1 gene and P-glycprotein(P-gp) expression in multidrug resistance human leukemia cell line K562/ adriamycin(ADM) in vitro. Method: After treated with 100

200 mg·L-1 SC for 24 h. The expression level of P-gp in K562/ADM was determined by western blot and transcription of mdr-1 gene was detected by semi-quantitative RT-PCR. The intracellular ADM concentration was tested by HPLC. The proliferation of K562/ADM cell line was determinde by MTT. Result: The relative efficiency of K562/ADM to ADM and the intracellular accumulation of ADM increased after SC treatment and the effect of 200 mg·L-1 SC was more obvious than that of 100 mg·L-1 SC(P<0.01);SC could inhibit the expression of mdr-1/P-gp according to results of semi-quantitative RT-PCR and Western blot(P<0.01)

the down-regulating rate on mdr-1/P-gp was(40.87±3.19)%and(35.08±0.09)% in 100 mg·L-1 SC group

(78.24±3.42)%and(79.61±0.23)% in 200 mg·L-1 SC group. Conclusion: SC could obviously inhibite the P-gp protein and mdr-1 gene expression and could effectively restore the sensitivity of K562/ADM cells to conventional chemotherapeutic.