Transcriptional specificities of adriamycin

The transcriptional effect of adriamycin using E. coli RNA polymerase on several single- and double-stranded DNAs of known base content and sequence is studied in vitro. The results show that adriamycin inhibits strongly and with little difference toward both poly[d(A-T)] and poly[d(G-C)] templates, and that it inhibits both single- and double-stranded DNA directed RNA synthesis, albeit the inhibition is clearly preferential to the double-stranded alternating copolymers over the double- and single-stranded homopolymers. Since adriamycin inhibition of RNA synthesis can be totally abolished when assayed in excess amount of DNA, the possibility that adriamycin may also directly inhibit the enzyme RNA polymerase per se is ruled out.