Production of protein-associated DNA breaks by 10-[diethylaminopropylamino]-6-methyl-5H-pyrido[3',4':4,5]pyrrolo [2,3-g]isoquinoline in cultured L1210 cells and in isolated nuclei: comparison with other topoisomerase II inhibitors.
10-[3-Diethylaminopropylamino]-6-methyl-5H-pyrido[3',4':4,5] pyrrolo[2,3-g]isoquinoline (PZE) is an ellipticine derivative currently in clinical trials. PZE has been postulated to produce cellular DNA lesions by an uncommon mechanism. PZE-induced DNA damage was further investigated in L1210 cells in culture. PZE was highly cytotoxic for these cells (90% inhibitory concentration = 3.1 microM). The effects of PZE on cellular DNA were studied first by alkaline sucrose sedimentation, in comparison with those of 4'-(9-acridinylamino)methanesulfon-m-anisidide (m-AMSA). Like m-AMSA, PZE induced DNA strand breaks which were detected without a proteolytic treatment of the cell lysate. This result rules out the existence of covalent protein bridges sealing DNA termini at the break sites. PZE was less active than m-AMSA. DNA fragmentation was maximum at 5 microM and was lower at higher concentrations. The DNA effects of PZE were also studied by alkaline elution, and compared with those of Adriamycin and m-AMSA. Like Adriamycin, PZE induced single-strand breaks (SSBs) in a bell-shaped manner with respect to drug concentration. The maximum SSB frequency [1784 +/- 370 (SEM) rad equivalents)] was obtained at 16 microM. The kinetics of SSB reversion after drug removal was slower than in the case of m-AMSA. Similar bell-shaped curves were obtained for PZE-induced double-strand breaks and DNA-protein cross-links. PZE induced more double-strand breaks per SSB than did m-AMSA. However, as in the case of m-AMSA, PZE induced equal SSB and DNA-protein cross-link frequencies. These results suggest that PZE induces DNA breaks by inhibiting topoisomerase II as do other antitumor intercalators.
Pierson
V
V
Sanofi Recherche, Toulouse, France.
Pierre
A
A
Pommier
Y
Y
Gros
P
P
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002467:Cell Nucleus / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D004247:DNA / Q000032:analysis; D004249:DNA Damage; D004277:DNA, Single-Stranded / Q000378:metabolism; D007211:Indoles; D007364:Intercalating Agents / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology*; D007939:Leukemia L1210 / Q000378:metabolism / Q000473:pathology; D011506:Proteins / Q000378:metabolism*; D059005:Topoisomerase II Inhibitors; D014407:Tumor Cells, Cultured / Q000187:drug effects
D000970:Antineoplastic Agents; D004277:DNA, Single-Stranded; D007211:Indoles; D007364:Intercalating Agents; D007546:Isoquinolines; D011506:Proteins; D059005:Topoisomerase II Inhibitors; C024256:pazelliptine; D004247:DNA