title: DNA breaks and repair in the mouse leukemia L1210 cells exposed to three different types of interstrand DNA cross-linkers.
abstract: DNA breaks and repair in mouse leukemia L1210 cells treated with 3 different types of cross-linkers, mitomycin C (MMC), 1-(4-amino-2-methyl-5-pyrimidinyl)-methyl-3-(2-chloroethyl)-3-nitroso ure a hydrochloride (ACNU) and SN-07 (a macromolecular antibiotic), were studied. Measured in D37 values, MMC gave the highest number of cross-links per lethal 'hit' directly after the 1-h treatment in the alkaline elution assay, followed by ACNU and SN-07. A good dose-response increase in induced interstrand DNA cross-linking frequency was observed in cells treated with 2.5-10 micrograms/ml MMC and with 10-100 micrograms/ml ACNU for 1 h with and without 24-h post-incubation. After 6-h post-incubation, the highest frequency of cross-linking was observed in cells treated with 2.5 micrograms/ml MMC and 30 micrograms/ml ACNU, while cross-link production continued in the cells treated with SN-07 for 12-h post-incubation. No significant increase in DNA breaks was observed in cells treated with MMC throughout 24-h post-incubation. The highest frequency of single-strand DNA breaks in cells treated with ACNU was observed immediately after the treatment and they disappeared after 6-h post-incubation. After 24-h post-incubation, a marked enhancement of the DNA breaks was observed in cells treated with SN-07 and the cells contained double-strand DNA breaks also. RNA synthesis was not affected in the cells treated with 10 micrograms/ml MMC and slightly inhibited to 70% of control in those treated with 100 micrograms/ml ACNU, while DNA synthesis in both cells was significantly inhibited after 24-h post-incubation. By contrast, both RNA and DNA synthesis were completely inhibited in cells treated with 8.0 micrograms/ml SN-07.
authors.affiliation: Research Institute of Life Science, Snow Brand Milk Products Co., Ltd., Tochigi, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Yajima
authors.forename: S
authors.initials: S
authors.lastname: Hochi
authors.forename: N
authors.initials: N
authors.lastname: Miyata
authors.forename: T
authors.initials: T
authors.lastname: Kishi
authors.forename: G
authors.initials: G
authors.lastname: Kawanishi
mesh_terms: D000818:Animals; D018943:Anthracyclines; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D004249:DNA Damage; D004260:DNA Repair; D004261:DNA Replication / Q000187:drug effects; D007700:Kinetics; D007939:Leukemia L1210; D051379:Mice; D016685:Mitomycin; D008937:Mitomycins / Q000494:pharmacology*; D015376:Nimustine / Q000494:pharmacology*; D012334:RNA, Neoplasm / Q000096:biosynthesis; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000187:drug effects*
chemical_list: D018943:Anthracyclines; D000903:Antibiotics, Antineoplastic; D000970:Antineoplastic Agents; D008937:Mitomycins; D012334:RNA, Neoplasm; D015376:Nimustine; C054281:barminomycin I; D016685:Mitomycin