title: Imatinib (STI571) induces DNA damage in BCR/ABL-expressing leukemic cells but not in normal lymphocytes.
abstract: Imatinib (STI571) is a 2-phenylaminopyrimidine derivative used mostly in the treatment of chronic myeloid leukaemia. It targets the BCR/ABL oncogenic tyrosine kinase, inhibiting its activity. Using the alkaline comet assay we showed that STI571 at concentrations ranging from 0.2 to 2 microM induced DNA damage in human leukemic K562 and BV173 cells expressing the BCR/ABL oncogene, whereas it had no effect in normal human lymphocytes and leukemic CCRF-CEM cells without the expression of BCR/ABL. Imatinib did not induce DNA strand breaks in the direct interaction with DNA as examined by the circular plasmid relaxation assay. Because the extent of DNA damage observed in the neutral and pH 12.1 versions of the comet assay was much lesser than in the alkaline version, we concluded that the drug induced DNA alkali-labile sites rather than strand breaks. K562 cells were unable to repair H(2)O(2)-induced DNA damage during a 120-min incubation, if they had been preincubated with STI571, whereas normal lymphocytes did so within 60 min. Pre-treatment of K562 cells with Vitamins A, C and E reduced the extent of DNA damage evoked by STI571. Similar results brought experiments with the nitrone spin traps POBN and PBN, suggesting that free radicals may be involved in the formation of DNA lesions induced by STI571 in K562 cells. These cells exposed to imatinib and treated with endonuclease III, formamidopyrimidine-DNA glycosylase and 3-methyladenine-DNA glycosylase II, the enzymes recognizing oxidized and alkylated bases, displayed greater extent of DNA damage than those not treated with these enzymes. Therefore, the mechanism of the anti-leukemic action of STI571 may involve not only the inhibition of BCR/ABL, but also DNA damage in the cells expressing this fusion protein. DNA damage induced by STI571 may follow from oxidative and alkylative base modifications.
authors.affiliation: Department of Molecular Genetics, University of Lodz, Ul. Banacha 12/16, 90-237 Lodz, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Czechowska
authors.forename: Tomasz
authors.initials: T
authors.lastname: Poplawski
authors.forename: Jozef
authors.initials: J
authors.lastname: Drzewoski
authors.forename: Janusz
authors.initials: J
authors.lastname: Blasiak
mesh_terms: D000328:Adult; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D001205:Ascorbic Acid / Q000494:pharmacology; D001549:Benzamides; D020552:Comet Assay; D004249:DNA Damage / Q000502:physiology*; D004260:DNA Repair / Q000502:physiology; D016044:Fusion Proteins, bcr-abl; D006801:Humans; D000068877:Imatinib Mesylate; D020014:K562 Cells; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics; D008214:Lymphocytes / Q000187:drug effects* / Q000201:enzymology; D008297:Male; D010879:Piperazines / Q000494:pharmacology*; D010957:Plasmids; D011505:Protein-Tyrosine Kinases / Q000096:biosynthesis* / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology*; D018709:Statistics, Nonparametric; D014801:Vitamin A / Q000494:pharmacology; D014810:Vitamin E / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D010879:Piperazines; D011743:Pyrimidines; D014801:Vitamin A; D014810:Vitamin E; D000068877:Imatinib Mesylate; D011505:Protein-Tyrosine Kinases; D016044:Fusion Proteins, bcr-abl; D001205:Ascorbic Acid