title: 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 KB-A-1 cells by 5.2 and 2.5 times, respectively, but no such effects were found on drug sensitive 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) decreased in the KB-3-1 cells, which was induced by different concentrations of doxorubicin, whereas the intracellular ROS induced by doxorubicin in KB-A-1 cells maintained a high level. Such observation suggests that drug resistant cells undergo oxidative stress. Furthermore, this elevated redox level in KB-A-1 cells was inhibited by either TP or EGCG. These results demonstrate that the reversal effect of TP and EGCG on MDR acts, at least in part, regulating the doxorubicin induced intracellular concentration of ROS.
authors.affiliation: Department of Molecular & Cellular Biochemistry, Chandler Medical Center, University of Kentucky, Lexington, Kentucky 40536, USA. yuyingmei@uky.edu
authors.forename: Yuying
authors.initials: Y
authors.lastname: Mei
authors.forename: Dongzhi
authors.initials: D
authors.lastname: Wei
authors.forename: Jianwen
authors.initials: J
authors.lastname: Liu
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D002392:Catechin / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D005419:Flavonoids / Q000494:pharmacology*; D006801:Humans; D007624:KB Cells; D018384:Oxidative Stress / Q000187:drug effects; D010636:Phenols / Q000494:pharmacology*; D059808:Polyphenols; D017382:Reactive Oxygen Species / Q000378:metabolism; D013662:Tea / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols; D017382:Reactive Oxygen Species; D013662:Tea; D004317:Doxorubicin; D002392:Catechin; C045651:epigallocatechin gallate