Effects of 3'-deamino-3'-(3-cyano-4-morpholinyl)doxorubicin and doxorubicin on the survival, DNA integrity, and nucleolar morphology of human leukemia cells in vitro.
The potential mechanisms of the extremely potent anthracycline analogue 3'-deamino-3'-(3-cyano-4-morpholinyl)doxorubicin (MRA-CN) have been compared with those of doxorubicin (DOX) by examination of drug effects on colony formation, macromolecular synthesis, DNA integrity, and ultrastructure of human leukemia cells in vitro. Following a 1-h exposure, MRA-CN was found to be 1400-fold more cytocidal than DOX which correlated with the drugs' inhibitory effects on DNA and total RNA synthesis. Treatment with MRA-CN resulted in a dose-dependent production of DNA interstrand cross-links as quantified by alkaline elution. One-h treatments with DOX or 3'-deamino-3'-(4-morpholinyl) doxorubicin (the non-cyano-containing analogue of MRA-CN) produced no DNA-DNA cross-links; rather they produced protein-concealed DNA single-strand breaks. After removal of MRA-CN, the DNA of KBM-3 cells displayed time-dependent fragmentation as indicated by rapid DNA filter elution during the pH 10 lysis step which preceded pH 12 elution. Within 4 h of MRA-CN exposure (10 nM, 1 h), 50% of the cellular DNA was in the lysis fraction. By 24 h, all the cellular DNA was in this fraction. MRA-CN (10 nM), 3'-deamino-3'-(4-morpholinyl)doxorubicin (1 microM), and actinomycin D (1 microM), but not DOX (3 mircroM), each produced distinctive nucleolar macrosegregation, indicating an effect on rRNA synthesis. The alpha-CN substituent on the morpholinyl moiety of MRA-CN appears to be responsible for the unique antitumor potency of this anthracycline. Nucleolar macrosegregation is probably associated with the morpholinyl moiety and is independent of the alpha-CN substituent.
D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D002466:Cell Nucleolus / Q000187:drug effects* / Q000473:pathology; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004273:DNA, Neoplasm / Q000378:metabolism*; D003609:Dactinomycin / Q000494:pharmacology; D004317:Doxorubicin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D006801:Humans; D007938:Leukemia / Q000378:metabolism; D012334:RNA, Neoplasm / Q000096:biosynthesis; D013329:Structure-Activity Relationship
D000903:Antibiotics, Antineoplastic; D004273:DNA, Neoplasm; D012334:RNA, Neoplasm; D003609:Dactinomycin; D004317:Doxorubicin; C038555:3'-deamino-3'-(3-cyano-4-morpholinyl)doxorubicin