Objective:To research the effect of total saponins Panax ginseng (TSPG) on the drug resistance of human erythroleukemia drug resistant cell line K562/A02 and its mechanism.Methods:The sensitivity of TSPG-treated K562/A02 cells to anticancer drugs was determined by MTT assay.Immunohistochemistry method was used to measure mdr-1 gene product P-gp and apoptosis regulation gene product bcl-2 expression. RT-PCR technique was used to examine mdr-1 mRNA expression.Results:In non-toxic dosages

TSPG strengthened the toxicity effect of doxorubicin on K562/A02 cells

while the reversing effect of TSPG was related to its concentration. Decrease in P-gp expression in K562/A02 cells was marked ( P <0.01) after 3 days of TSPG(150μg/ml)application to K562/A02 cells

but the change in bcl-2 protein expression was insignificant ( P >O. 05)after 3 days of TSPG(150μg/ml)treatment.Decrease in mdr-1 mRNA expression was significant ( P <0.01)after 24 hours of TSPG(150μg/ml) treatment.Conclusion:TSPG partly reverses the drug resistance of K562/A02 cells. The main mechanism by which TSPG reverses the drug resistance of K562/A02 cells is decreasing the expression of mdr-1 mRNA

which then decreases P-gp

the product of mdr-1 mRNA. The relationship between be 1-2 protein expression and the mechanism by which TSPG reverses the drug resistance of K562/A02 cells is not clear.