BACKGROUND: Multidrug resistance (MDR) is a main reason for paclitaxel (TAX) 
treatment failure. Indirubin-3'-monoxime (IRO) and Matrine are traditional 
Chinese medicines, which may reverse the resistance of tumor cells to some 
chemotherapy drugs, but the relationship between paclitaxel resistance and 
Matrine is still unclear. The aim of this study was to explore the potential 
molecular mechanism of IRO and Matrine in reversal of TAX resistance.
METHODS: In this study, MTT assay was used to measure the non-cytotoxic dosage 
of IRO and Matrine on NCI-H520/TAX25 cells and determine the reversal extent of 
TAX resistance under non-toxic doses. In addition, RT-PCR and Western blotting 
were used to evaluate the mRNA expression and the protein level of survivin, 
Oct-4, and Sox-2 in NCI-H520/TAX25 cells using semi-quantitative methods.
RESULTS: There was no obvious inhibition on sensitive cell strains and 
drug-resistant strains, when the final concentration was at lest 4 µmol/L for 
IRO and 100 µmol/L for Matrine. So 4 µmol/L of IRO and 100 µmol/L of Matrine 
were considered as the reversal dosage. When 4 µmol/L of IRO or 100 µmol/L of 
Matrine were used together with TAX, the sensitivity to TAX increased evidently 
in NCI-H520/TAX2 cells; the reversal rate of IRO and Matrine was about 1.92 
(43.56/22.6 nmol/L) and 1.74 (43.56/25.0 nmol/L), respectively. The mRNA 
expression and the protein level of survivin, Oct-4, and Sox-2 in NCI-H520/TAX25 
decreased significantly (P < 0.05) after addition of IRO or Matrine in TAX 
treatment, compared to that of TAX treatment alone.
CONCLUSION: The decrease in both mRNA expression and protein level of survivin, 
Oct-4, and Sox-2 might be the molecular mechanism, by which IRO and Matrine 
mediate the reversal of TAX resistance.