Objective:To investigate the effect and mechanism of Jiedu Quyu prescription on drug resistance reversal for MCF-7/ADM human breast cancer cells. Method:The 3-(4

5-dimethylthiazol-2-yl)-2

5-diphenyltetrazolium bromide (MTT) was performed to test the effect of Jiedu Quyu prescription on proliferation of MCF-7/ADM cells. Flow cytometry was used to detect the concentration of intracellular rhodamine (Rh)-123

Real-time PCR and Western blot were used to analyze the expression of genes and proteins

including multiple drug resistant 1 (MDR1) and breast cancer resistant protein (BCRP). Result:After treatment with 1.25

2.50 g·L-1 Jiedu Quyu prescription

the reverse fold (RF) of MCF-7/ADM was 1.7 and 3.0 respectively (P <0.05); the concentration of intracellular Rh-123 was enhance for 1.8 and 2.5 times respectively as compared with control group (P <0.05). The protein and mRNA expression levels of MDR1 and BCRP were down-regulated obviously (P <0.05); MDR1 mRNA expression level was decreased by 35.5% and 56.0% respectively (P <0.05)

while BCRP mRNA expression level was decreased by 41.6% and 49.5% respectively (P <0.05). Conclusion:Jiedu Quyu prescription could enhance the sensitivity of human breast cancer cell line MCF-7/ADM to adriamycin

and reverse drug resistance of MCF-7/ADM. Its mechanism may be correlated with down-regulation of MDR1 and BCRP

as well as inhibition of intracellular drug efflux.