[Antitumor agents targeting mammalian topoisomerases]

Topoisomerase II is now viewed as an important cellular target of antitumor drugs including both DNA intercalators (m-AMSA, ellipticine and Adriamycin) and the nonintercalator epipodophyllotoxin derivatives (VP-16 and VM-26). Topoisomerase I is also shown to be the cellular target of camptotecin. These drugs targeting topoisomerase have been used to establish a relationship between drug-induced cleavable complex formation and cytotoxicity. Mechanistically oriented screening based on the identification of these chemotherapeutic targets have identified a number of antitumor agents that induce topoisomerases mediated DNA cleavage. The new antitumor drugs targeting topoisomerases are reviewed.