Daunomycin inhibition of DNA and RNA synthesis

Daunomycin is a new antibiotic with antitumor activity against a variety of solid and ascites forms of transplantable animal tumors. It is effective in acute leukemias and certain solid tumors in children. Daunomycin has been considered to inhibit preferentially RNA synthesis, with inhibition of DNA only at higher concentrations, therefore having a biologic mechanism of action similar to actinomycin. The effect of this antibiotic on the 32P incorporation into DNA and RNA of 6C3HD ascites tumor in vitro and in vivo and also on the regenerating mouse liver after partial heptectomy has been studied. These observations indicate that Daunomycin is a more effective inhibitor of the synthesis of DNA than RNA, and hence the biologic mechanism of action of this antibiotic is probably different from that of actinomycin.