Evidence that mAMSA induces topoisomerase action

Abstract
Evidence is presented that the topoisomerase inhibitors novobiocin and coumermycin inhibit the production of double-strand breaks in mouse mastocytoma cell nuclear DNA by the anticancer drug 4′[(9-acridinyl)amino]-methanesulphon-m-anisidide (mAMSA). Novobiocin did not inhibit resealing of DNA breaks induced by mAMSA. It is suggested that mAMSA intercalation into DNA induces the action of a type II topoisomerase. mAMSA and oAMSA were equally effective in breaking the DNA in isolated nuclei.