[BD-40, intercalating 9-azaellipticine derivative, induces breaks in cellular DNA associated with protein bridges]

The nature of the lesions induced in cell DNA by BD-40, a chemical analog of Ellipticine was analyzed by submitting DNA from drug-treated cells to alkaline sucrose gradient centrifugation. DNA size reduction was only observed when cell lysates were digested by proteolytic enzymes. This result indicates that BD-40 induces DNA breaks which are masked by bridges involving DNA-protein interaction. This is a new type of DNA lesion induced in DNA by an intercalating agent.