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CHO mutants resistant to colchicine, colcemid or griseofulvin have an altered beta-tubulin

F Cabral, M E Sobel, M M Gottesman

    Cell
    |May 1, 1980
    PubMed

    Insights

    Researchers identified Chinese hamster ovary (CHO) cell mutants resistant to anti-mitotic drugs. These mutants exhibit alterations in beta-tubulin, indicating a genetic basis for drug resistance in these cells.

    Area of Science:

    • Cell Biology
    • Genetics
    • Biochemistry

    Background:

    • Anti-mitotic drugs like colchicine, colcemid, and griseofulvin target microtubule polymerization.
    • Understanding cellular resistance mechanisms is crucial for cancer therapy and drug development.
    • Chinese hamster ovary (CHO) cells are a widely used model system in toxicology and genetics.

    Purpose of the Study:

    • To isolate and characterize single-step mutants of CHO cells resistant to anti-mitotic drugs.
    • To investigate the molecular basis of drug resistance in these mutants.
    • To determine if resistance is due to alterations in beta-tubulin or changes in cell permeability.

    Main Methods:

    • Isolation of drug-resistant CHO cell mutants.
    • Two-dimensional gel electrophoresis to analyze protein alterations.
    • In vitro translation assays using reticulocyte lysate to assess mRNA.
    • Cross-resistance studies to differentiate between beta-tubulin and permeability mutants.

    Main Results:

    • Several mutants resistant to colchicine, colcemid, or griseofulvin were isolated.
    • Two-dimensional gel analysis revealed alterations in the beta-tubulin subunit in some resistant mutants.
    • Mutants showed reduced wild-type beta-tubulin and an additional, more basic isoelectric point variant.
    • Messenger RNAs for both wild-type and variant beta-tubulins were detected, ruling out post-translational modification.

    Conclusions:

    • Single-step mutations in CHO cells can confer resistance to anti-mitotic drugs.
    • Alterations in the beta-tubulin protein are a primary mechanism for resistance to certain anti-mitotic agents.
    • The observed beta-tubulin variants result from changes at the genetic level, not post-translational modification.

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