DNA topoisomerases and topoisomerase inhibitors.

DNA topoisomerases are ubiquitous nuclear enzymes, essential for several steps of DNA metabolism. They have recently been shown to be specific targets of a number of anticancer agents. In this review are discussed the most recent discoveries in the physiology and the molecular biology of DNA topoisomerases, and the mechanism of interaction with drugs. In addition, alterations of DNA topoisomerases are also described, as potential responsible of drug resistance.