Golgi complex in brefeldin A resistant in multidrug resistant cells

The multidrug resistance (MDR) is one of the main reasons for chemotherapeu tic failures in cancer patients, The overexpression of an MDR1 gene product , P-glycoprotein (Pgp), leads to the appearance of resistant tumor cells, I n the previous paper(Erokhina, 1997) we demonstrated that the first stages of the Pep-mediated MDR are accompanied by the reorganization of cytoskelet on elements and the vacuolar system. These data were true for two independe ntly isolated sublines of Syrian hamster embryo fibroblasts transformed by the Raus sarcoma virus, In this study we continued the investigation of pro perties of the vacuolar system in Pgp-expressing cells. Brefeldin A (BFA), which is not a Pgp substrate, affects different elements of vacuolar system and blocks vesicular transport, Our data demonstrate that BFA has differen t effects on parental and resistant cells, In parental-cells, the Golgi app aratus and vesicular transport are sensitive to BFA, while in resistant sub lines, BFA affects the vesicular transport, but not the Golgi apparatus str ucture. We discuss the existance of similar and different BFA targets in pa rental and resistant cells and their role in the evolution of multidrug res istant mechanisms.