title: The contribution of deficient DNA repair to chromosomal radiosensitivity of CHO cells after G2 irradiation.
abstract: We compared cytogenetic responses of the parental Chinese hamster ovary (CHO) cell line and its DNA repair-deficient strains to irradiation during the G2 phase. Chromatid breaks were quantified in cells entering metaphase in the presence or absence of cytosine arabinoside (ara-C) 0.5-1.5 hours after exposure to x-rays or UV-C. Addition of ara-C, an inhibitor of DNA repair replication, significantly increased chromatid break frequency (CBF) in the parental line, but not in the strains deficient in nucleotide excision repair (NER). This increase (ara-C effect) was comparable to that in repair-proficient normal human lymphocytes. We conclude that CBF in cells entering metaphase in the presence of ara-C 0.5-1.5 hours after DNA damage represents a functional in vitro assay for evaluating the DNA repair capacity of mammalian cells in culture.
authors.affiliation: Laboratory of Cellular and Molecular Biology, National Cancer Institute, Bethesda, Maryland, USA.
authors.forename: K K
authors.initials: KK
authors.lastname: Sanford
authors.forename: R
authors.initials: R
authors.lastname: Parshad
mesh_terms: D000818:Animals; D016466:CHO Cells; D002455:Cell Division / Q000187:drug effects / Q000528:radiation effects; D002460:Cell Line; D002869:Chromosome Aberrations; D002875:Chromosomes / Q000187:drug effects / Q000528:radiation effects; D006224:Cricetinae; D003561:Cytarabine / Q000494:pharmacology*; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair / Q000187:drug effects* / Q000528:radiation effects*; D045643:DNA Repair Enzymes; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects / Q000528:radiation effects*; D000075223:Poly-ADP-Ribose Binding Proteins; D011836:Radiation Tolerance; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection; D014466:Ultraviolet Rays; D014965:X-Rays