Induction and distribution of damage in CHO-K1 and the X-ray-sensitive hamster cell line xrs5, measured by the cytochalasin-B-cytokinesis block micronucleus assay

PJ Johnston, E Stoppard, Peter Edward Bryant

Research output: Contribution to journalArticlepeer-review

Abstract

The micronucleus assay holds promise as a method for determining clastogenic effects of particular agents and for examining relative sensitivities of eukaryotic cells to such clastogens, In the following work, a detailed examination of the induction of micronuclei in radio-resistant Chinese hamster ovary fibroblasts (CHO-K1) and the DNA double-strand break repair-defective daughter cell line, xrs5, was performed. Cells were exposed to gamma-irradiation, bleomycin, etoposide, camptothecin and the restriction endonuclease P upsilon uII. By a simplified statistical analysis of data, information on the expression of chromosomal damage, the distribution of damage and the role of cell cycle effects on damage expression was obtained from a relatively small number of cells. Ail 5 clastogens resulted in elevated levels of micronuclei in xrs5 compared to CHO-K1. An analysis of the distribution of micronuclei within treated populations revealed differences between the modes of damage. Significant deviation from the expected values indicated that expression of micronuclei does not follow an expected Poisson distribution, The frequencies of binucleated cells;indicated micronucleus frequencies do not correlate with inhibition of cell cycle progression. This work also demonstrates that caution is required in the interpretation of data obtained through micronucleus assays. In particular, it does not appear possible to proscribe simple numerical values of relative sensitivity or clastogenicity based on the relative number of micronuclei induced alone, (C) 1997 Elsevier Science B.V.

Original languageEnglish
Pages (from-to)1-12
Number of pages12
JournalDNA Repair
Volume385
Issue number1
DOIs
Publication statusPublished - Oct 1997

Keywords

  • etoposide
  • camptothecin
  • bleomycin
  • restriction endonuclease
  • streptolysin-O
  • DOUBLE-STRAND BREAKS
  • SISTER-CHROMATID EXCHANGES
  • CHROMOSOMAL-ABERRATIONS
  • MUTANT-CELLS
  • TOPOISOMERASE-II
  • CYTOGENETICAL CHARACTERIZATION
  • CYTOLOGICAL CHARACTERIZATION
  • RESTRICTION ENDONUCLEASES
  • MAMMALIAN-CELLS
  • DNA

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