Taxol has been regarded as one of the most successful anti-cancer drugs identified from natural sources to date. Although Taxol is known to sensitize cells by stabilizing microtubules, its ability to cause DNA damage in peripheral blood lymphocytes and to induce oxidative stress and apoptosis indicates that Taxol may have other modes of cytotoxic action. This study focuses on identifying the additional targets of Taxol that may contribute to its multifaceted cell killing property, using Saccharomyces cerevisiae. We show that yeast oxidative stress response mutants (sod1Δ, tsa1Δ and cta1Δ) and DNA damage response mutants (mre11∆, sgs1∆ and sub1∆) are highly sensitive to Taxol. Our results also show that Taxol increases the level of reactive oxygen species (ROS) in yeast oxidative stress response mutant strains. Further, 4',6-Diamidino-2'-phenylindole (DAPI) and acridine orange/ethidium bromide (AO/EB) staining show that Taxol induces apoptotic features such as nuclear fragmentation and chromatin condensation in DNA repair mutants. On the whole, our results suggest that Taxol's cytotoxic property is attributed to its multifaceted mechanism of action. Yeast S. cerevisiae anti-oxidant and DNA repair gene mutants are sensitive to Taxol compared to wild-type, suggesting yeast model can be used to identify the genetic targets of anti-cancer drugs.
Keywords: Saccharomyces cerevisiae; DNA damage response; Taxol; oxidative stress.
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