Topoisomerase II alpha, rather than II beta, is a promising target in development of anti-cancer drugs

DNA topoisomerase II (TOP2) is a wellknown anticancer target. Its inhibitors are among the most effective anticancer drugs currently in clinical use. TOP2-targeting agents fall into two major classes of "Topo poisons" and "Topo inhibitors" based on their mechanisms of action. Mammalian cells possess two genetically distinct TOP2 isoforms, TOP2 alpha and TOP2 beta, that are differentially regulated and play different roles in living cells. Compared to TOP2 beta, TOP2 alpha may be an efficacious and safe chemotherapeutic target for cancer treatment. This review discusses the advantage of targeting TOP2 alpha over TOP2 beta and action of various agents on TOP2 alpha.