Adriamycin-induced compaction of isolated chromatin

Adriamycin and certain other agents such as daunomycin, rubidazone and 1,4-dihydroxyl-5,8 bis [[2-[(2-hydroxyethyl)amino]ethyl]amino]-9,10-anthracenedione (DHAQ) were capable of inducing a considerable increase in the sedimentation rate of isolated chromatin. In contrast, N-trifluoroacetyl-adriamycin-14-valerate (AD-32) was without effect in this system. Electron microscope studies of chromatin incubated with adriamycin, rubidazone and DHAQ showed that all of these drugs were capable of inducing the formation of highly condensed DNA structures. When chromatin was treated with 0.4 M NaCl, its ability to serve as a substrate for adriamycin-induced compaction was abolished. However, the salt-treated chromatin could still be condensed by DHAQ and rubidazone. The results of this study, therefore, show that a variety of closely related antitumor agents are capable of condensing isolated chromatin. However, certain of these compounds had distinct substrate requirements for the compaction reaction.