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Unscheduled DNA synthesis induced by streptonigrin in ataxia telangiectasia fibroblasts

A M Taylor, H B Laher, G R Morgan

    Carcinogenesis
    |June 1, 1985
    PubMed

    Insights

    Streptonigrin antibiotic causes DNA strand breaks in cultured cells. Ataxia telangiectasia (A-T) cells show sensitivity to this DNA damage, indicating a repair deficiency in A-T cells.

    Area of Science:

    • Molecular Biology
    • Genetics
    • Pharmacology

    Background:

    • Streptonigrin is an antitumour antibiotic with known DNA-damaging properties.
    • It affects DNA synthesis and colony-forming ability at low doses.
    • Higher doses can induce unscheduled DNA synthesis (UDS), suggesting excision repair of DNA adducts.

    Purpose of the Study:

    • To investigate the sensitivity of Ataxia telangiectasia (A-T) cells to streptonigrin.
    • To determine if A-T cells can perform excision repair of streptonigrin-induced DNA damage.
    • To elucidate the specific mechanism of streptonigrin's action in A-T cells.

    Main Methods:

    • Exposure of cultured cells, including A-T cells and normal cells, to streptonigrin.
    • Measurement of unscheduled DNA synthesis (UDS) as an indicator of excision repair.
    • Assessment of DNA strand breaks and their repair capacity.

    Main Results:

    • A-T cells demonstrated unusual sensitivity to streptonigrin.
    • A-T cells exhibited excision repair capacity, measured by UDS, comparable to normal cells.
    • The DNA strand-breaking effect of streptonigrin appears to be the primary cause of sensitivity in A-T cells.

    Conclusions:

    • A-T cells possess excision repair capabilities for streptonigrin-induced DNA damage.
    • The heightened sensitivity of A-T cells to streptonigrin is linked to its DNA strand-breaking activity.
    • This finding supports the hypothesis that A-T cells have a deficiency in repairing certain types of DNA strand breaks.

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