The combined effects of proteasome inhibitor bortezomib with topoisomerase I and II inhibitors on topoisomerase enzymes.

Background/aim: DNA topoisomerases are ubiquitous enzymes that regulate conformational changes in DNA topology during essential cellular processes, and, for this reason, have been characterized as the cellular targets of a number of anticancer drugs. Bortezomib is a powerful proteasome inhibitor used in the treatment of hematological malignancies. In this study, we investigated the inhibitory effects of bortezomib on human topoisomerase I and II enzymes both alone and in combination modes with camptothecin and etoposide.