Studying DNATopoisomerase I-Targeted Drugs In the Yeast: Saccharomyces cerevisiae

The budding yeast Saccharomyces cerevisiae has been a valuable model in establishing eukaryotic DNA topoisomerase I as the cellular target of specific antineoplastic agents, including camptothecin (1 –3 ), aclacinomycin A (4 ), and R-3, a rebeccamycin analogue (Vance, J. R., Woo, M. H., Otero, A., Bailly, C., and Bjornsti, M. A., unpublished results). This genetically tractable eukaryote has also been useful in studying mechanisms of resistance to DNA topoisomerase I-targeted drugs and providing information about drug funcion, cell cycle specificity, mutations affecting drug sensitivity, and the cellular consequences of drug treatment (reviewed in refs. 3 ,5 ).