Reversal of multidrug resistance in KB cells with tea polyphenol antioxidant capacity

Abstract

Tea polyphenol (TP), (-)-epigallocatechin gallate (EGCG) in particular, were examined for their reversal effects on multidrug resistance (MDR) with their antioxidant capacities. TP and EGCG were proved to exert reversal effects on drug resistance of KB-A-1 cells by 5.2 and 2.5 times, respectively, but no such effects were found on KB-3-1 cells. With a redox indicator 6 – carboxy - 2’,7’ - dichlorodihydrofluorescein (CDCFH), it could be found that the intracellular reactive oxygen species (ROS) was in a decreasing manner in the KB-3-1 cells, which was induced by defferent concentrations of doxorubicin, whereas the intracellular ROS induced by doxorubicin in KB-A-1 cells maintained at a high level. Such observation suggests that drug resistance cells undergo oxidantive stress. Furthermore, this elevated redox level in KB-A-1 cells is inhibited by either TP or EGCG. Thus, these results demonstrate that the reversal effect of TP and EGCG on MDR through, at least in part, regulating the doxorubicin induced intracellular concentration of ROS.