ePrints

Isolation and partial characterisation of a mammalian cell mutant hypersensitive to topoisomerase II inhibitors and X-rays

Lookup NU author(s): Dr Sally Davies, Dr Andrew Hall

Downloads

Full text for this publication is not currently held within this repository. Alternative links are provided below where available.

Abstract

We have isolated, following one-step mutagenesis, a Chinese hamster ovary cell mutant hypersensitive to the intercalating agent, adriamycin (4-fold compared to parental CHO-K1 cells). This agent exerts at least part of its cytotoxic action via inhibition of the nuclear enzyme, topoisomerase II. The mutant, designated ADR-3, showed hypersensitivity to all classes of topoisomerase II inhibitors, including actinomycin D, amsacrine (m-AMSA), etoposide (VP16) and mitoxantrone. ADR-3 cells also showed cross-sensitivity to ionizing radiation, but not to UV light. Cellular accumulation of radiolabeled actinomycin D was similar in parental and mutant cells. At equimolar doses, adriamycin induced more protein-associated DNA single- and double-strand breaks in ADR-3 cells than in CHO-K1 cells. Topoisomerase II activity was elevated to a small but significant degree in ADR-3 cells, and this was reflected in a 1.5-fold higher level of topoisomerase II protein in ADR-3 than in CHO-K1 cells, as judged by Western blotting. ADR-3 cells were hypersensitive to cumene hydroperoxide but cross-resistant to hydrogen peroxide, suggesting possible abnormality in the detoxification of peroxides by glutathione peroxidase or catalase. Glutathione peroxidase activity against hydrogen peroxide was similar in CHO-K1 and ADR-3 cell extracts, but activity against cumene hydroperoxide was evaluated to a small but significant extent in mutant cells. Catalase levels were not significantly different in ADR-3 and CHO-K1 cells. ADR-3 cells were recessive in hybrids with parental CHO-K1 cells with respect to sensitivity to topoisomerase II inhibitors and X-rays, and represent a different genetic complementation group from the previously reported adriamycin-sensitive mutant, ADR-1 [Davies et al., J. Biol. Chem., 263 (1988) 17724-17729].

Publication metadata

Author(s): Davies SM, Davies SL, Hall AG, Hickson ID

Publication type: Article

Publication status: Published

Journal: Mutation Research / DNA Repair

Year: 1990

Volume: 235

Issue: 2

Pages: 111-118

Print publication date: 01/03/1990

ISSN (print): 1568-7864

ISSN (electronic): 1568-7856

URL: http://dx.doi.org/10.1016/0921-8777(90)90064-C

DOI: 10.1016/0921-8777(90)90064-C

PubMed id: 2155384

Altmetrics

Share