<?xml version='1.0' encoding='UTF-8'?><xml><records><record><source-app name="HighWire" version="7.x">Drupal-HighWire</source-app><ref-type name="Journal Article">17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">FERREIRA, MARIA-JOSÉ U.</style></author><author><style face="normal" font="default" size="100%">DUARTE, NOÉLIA</style></author><author><style face="normal" font="default" size="100%">GYÉMÁNT, NORA</style></author><author><style face="normal" font="default" size="100%">RADICS, RITA</style></author><author><style face="normal" font="default" size="100%">CHEREPNEV, GEORGY</style></author><author><style face="normal" font="default" size="100%">VARGA, ANDRAS</style></author><author><style face="normal" font="default" size="100%">MOLNÁR, JOSEPH</style></author></authors><secondary-authors></secondary-authors></contributors><titles><title><style face="normal" font="default" size="100%">Interaction between Doxorubicin and the Resistance Modifier Stilbene on Multidrug Resistant Mouse Lymphoma and Human Breast Cancer Cells</style></title><secondary-title><style face="normal" font="default" size="100%">Anticancer Research</style></secondary-title></titles><dates><year><style  face="normal" font="default" size="100%">2006</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2006-09-01 00:00:00</style></date></pub-dates></dates><pages><style  face="normal" font="default" size="100%">3541-3546</style></pages><volume><style face="normal" font="default" size="100%">26</style></volume><issue><style face="normal" font="default" size="100%">5A</style></issue><abstract><style  face="normal" font="default" size="100%">The hydroxystilbene trans-3,5,3′,4′-tetrahydroxystilbene (piceatannol) (1), isolated from the methanol extract of Euphorbia lagascae defatted seeds, was methylated to yield the derivatives trans-3,5,3′,4′-tetramethoxystilbene (2), (trans-3,5-dihydroxy-3′,4′-dimethoxystilbene) (3) and trans-3,5,3′-trihydroxy-4′-methoxystilbene (4). The structures of the compounds were assigned by spectroscopic methods (IR, 1H-NMR, 13C-NMR and MS). The ability of piceatannol (1) and the three methylated derivatives to modulate the transport activity of P-glycoprotein (P-gp) and apoptosis induction on the L5178 mouse lymphoma cell line containing the human MDR1 gene was studied by flow cytometry. The reversal of multidrug-resistance (MDR) was investigated by measuring the accumulation of rhodamine-123, a fluorescent substrate analog of doxorubicin, in cancer cells. Verapamil was applied as a positive control. For the evaluation of the compounds as apoptosis inducers, tumor cells were stained with FITC-labelled annexin-V and propidium iodide. The tetramethylated derivative (2) was found to be a powerful inhibitor of P-gp activity. Compounds 1 and 2 showed an increased apoptotic effect in the MDR subline, the most active being piceatannol (1). Furthermore, in the combination chemotherapy model, the interaction between doxorubicin and the resistance modifier 2 was studied in vitro. The results of checkerboard experiments indicated that the type of interaction was additive between doxorubicin and compound 2 on the human MDR1 gene-transfected mouse lymphoma cells. However, in the MCF7/dox human breast cancer cells, the interaction was non-additive. The degree of additive and non-additive interactions were close to the borderline of the FIX values corresponding to the two types of interactions. Copyright© 2006 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved</style></abstract></record></records></xml>