title: Leukaemia-specific chromosome damage detected by comet with fluorescence in situ hybridization (comet-FISH).
abstract: Acute myeloid leukaemia (AML) is associated with exposure to benzene and treatment with chemotherapeutic agents. It is thought to arise from damage to specific regions of DNA, resulting in chromosome rearrangements or loss. For instance, a deletion on the long arm of chromosome 5 [e.g. del(5q31)] is common in AML patients previously treated with alkylating agents, such as melphalan, or exposed to benzene. Translocations of the MLL gene at 11q23 are frequently observed in AML arising from treatment with topoisomerase II inhibitors, such as etoposide. Our goal was to determine whether or not breakage at 5q31 and 11q23 is selectively induced by these chemical agents. To address this question, the comet assay combined with fluorescence in situ hybridization (comet-FISH) was used to detect DNA breakage in the specific chromosomal regions in an in vitro model. TK6 lymphoblastoid cells were exposed to melphalan, etoposide or the benzene metabolite, hydroquinone (HQ), at various concentrations. HQ, melphalan and etoposide induced DNA breaks at both 5q31 and 11q23 chromosome regions in a dose-dependant manner. However, HQ produced significantly more DNA damage at 5q31 than at 11q23. Etoposide produce slightly more DNA damage at 11q23 and melphalan had a somewhat greater effect at 5q31, but not significantly so. Thus, HQ and melphalan act similarly, perhaps explaining some similarities between benzene- and alkylating agent-induced AML. Comet-FISH also appears to be a useful approach for detecting and comparing damage to specific chromosome regions of significance in leukaemogenesis.
authors.affiliation: Division of Environmental Health Sciences, School of Public Health, 140 Warren Hall, University of California, Berkeley, California 94720, USA.
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Escobar
authors.forename: Martyn T
authors.initials: MT
authors.lastname: Smith
authors.forename: Ananth
authors.initials: A
authors.lastname: Vasishta
authors.forename: Alan E
authors.initials: AE
authors.lastname: Hubbard
authors.forename: Luoping
authors.initials: L
authors.lastname: Zhang
mesh_terms: D000477:Alkylating Agents / Q000633:toxicity*; D045744:Cell Line, Tumor; D002880:Chromosomes, Human, Pair 11 / Q000187:drug effects* / Q000648:ultrastructure; D002895:Chromosomes, Human, Pair 5 / Q000187:drug effects* / Q000648:ultrastructure; D020552:Comet Assay / Q000379:methods*; D004249:DNA Damage; D011495:Histone-Lysine N-Methyltransferase; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D015470:Leukemia, Myeloid, Acute / Q000139:chemically induced / Q000235:genetics*; D008214:Lymphocytes / Q000187:drug effects / Q000648:ultrastructure; D051788:Myeloid-Lymphoid Leukemia Protein / Q000235:genetics; D014178:Translocation, Genetic
chemical_list: D000477:Alkylating Agents; C497422:KMT2A protein, human; D051788:Myeloid-Lymphoid Leukemia Protein; D011495:Histone-Lysine N-Methyltransferase