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DNA damage by antitumor acridines mediated by mammalian DNA topoisomerase II

T C Rowe, G L Chen, Y H Hsiang

    Cancer Research
    |April 1, 1986
    PubMed

    Insights

    Antitumor drugs cause DNA breaks by targeting mammalian DNA topoisomerase II. This enzyme mediates drug-induced DNA damage and cytotoxicity, suggesting it

    Area of Science:

    • Molecular Biology
    • Cancer Research
    • Biochemistry

    Background:

    • Antitumor drugs from various chemical classes induce protein-linked DNA breaks in mammalian cells and in vitro.
    • Mammalian DNA topoisomerase II is a potential intracellular target mediating these drug-induced DNA breaks.

    Purpose of the Study:

    • To investigate if mammalian DNA topoisomerase II is an intracellular target for antitumor drugs.
    • To explore the role of topoisomerase II-mediated DNA breaks in drug-induced cytotoxicity.

    Main Methods:

    • Purification of calf thymus DNA topoisomerase II.
    • Assaying m-AMSA-dependent DNA cleavage activity.
    • Analyzing protein-DNA covalent attachment via tyrosyl phosphate bonds.
    • Correlating in vitro DNA breaks with cellular DNA breaks and cytotoxicity using m-AMSA-related acridines.

    Main Results:

    • A single m-AMSA-dependent DNA cleavage activity copurified with DNA topoisomerase II.
    • m-AMSA induced DNA cleavage resulted in covalent protein attachment to DNA 5'-ends.
    • The covalently linked protein matched the molecular weight of purified DNA topoisomerase II.
    • In vitro topoisomerase II-mediated DNA breaks strongly correlated with cellular DNA breaks and cytotoxicity.

    Conclusions:

    • Mammalian DNA topoisomerase II is a likely intracellular target for antitumor drugs.
    • Topoisomerase II-mediated DNA breaks are implicated in the cytotoxic effects of antitumor acridines.

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