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Inhibition of post-replication repair by isonicotinic acid hydrazide

O L Klamerth

    Mutation Research
    |May 1, 1978
    PubMed

    Insights

    Ionicotinic acid hydrazide (INH) inhibits DNA repair in Chinese hamster cells and reduces cell division in human lymphocytes when exposed to the mutagen N-methyl-N-nitrosourea (MNU). INH did not affect unscheduled DNA synthesis.

    Area of Science:

    • Molecular biology
    • Cell biology
    • Toxicology

    Background:

    • Ionicotinic acid hydrazide (INH) is a known tuberculostatic drug.
    • Alkylating mutagens like N-methyl-N-nitrosourea (MNU) can induce DNA damage.
    • DNA repair mechanisms are crucial for maintaining genomic integrity.

    Purpose of the Study:

    • To investigate the effects of INH on DNA repair and cell proliferation in the presence of MNU.
    • To determine if INH affects different DNA repair pathways.

    Main Methods:

    • Exposure of peripheral human lymphocytes to MNU and INH.
    • Assessment of cell number and mitotic index in human lymphocytes.
    • Exposure of Chinese hamster cells (CHO) to MNU and INH.
    • Analysis of post-replication repair and unscheduled DNA synthesis in CHO cells.

    Main Results:

    • INH, even at low doses, decreased cell number and mitotic index in human lymphocytes exposed to MNU.
    • INH inhibited the post-replication repair process in CHO cells treated with MNU.
    • INH did not influence unscheduled DNA synthesis in CHO cells.

    Conclusions:

    • INH exhibits genotoxic effects by interfering with DNA repair and cell proliferation.
    • The findings suggest INH may potentiate the mutagenic effects of MNU.
    • INH specifically inhibits post-replication repair, not unscheduled DNA synthesis.

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