Reversal of multidrug resistance and inhibition of DNA topoisomerase Ⅱ by emulsion of seed oil of Brucea Javanica / 中国药理学通报

ABSTRACT

AIM To explore the reversal effect of multidrug resistance (MDR) and the influence on topoisomerase (TOPO) activity by emulsion of seed oil of Bbrucea Javanica (ESOBJ) in vitro . METHODS Cytotoxic effects of ESOBJ against sensitive and resistance tumor cells were deter mined by MTT assay. Influences of ESOBJ on the catalytic activities of TOPO Ⅰ and TOPO Ⅱ were measured by TOPO Ⅰ mediated negatively super coiled pBR322 relaxation and TOPOⅡ mediated kDNA decatenation. RESULTS 0 025 g?L -1 of ESOBJ could reverse MDR in various MDR cell lines such as K562/A02?MCF 7/ADM and KB/VCR. DNA TOPO Ⅱ mediated kDNA decatenation experiment showed marked inhibitory action of ESOBJ on TOPO Ⅱ activity at the concentration of 0 31 g?L -1 and TOPO Ⅱ activity was totally inhibited by ESOBJ at the concentration of 2 5 g?L -1 . On the other hand, ESOBJ exhibited no influence on DNA TOPO I mediated pBR322 relaxation and on DNA directly. CONCLUSION ESOBJ could reverse MDR to a certain extent in vitro , and inhibit the activity of TOPO Ⅱ significantly.