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Published on: June 6, 2017
Isolation of hydroxyurea-resistant CHO cells with altered levels of ribonucleotide reductase
Abstract:
A Chinese hamster ovary cell line selected for resistance to hydroxyurea was serially cultivated in the absence of a selective agent, and cells with decreased resistance to the cytotoxic effects of hydroxyurea gradually accumulated in the population. Three stable subclones with differing drug sensitivities were isolated from this mixed population and were found to contain intracellular levels of drug-sensitive ribonucleotide reductase which correlated with the degree of cellular resistance to hydroxyurea. This new class of hydroxyurea resistance was expressed in a codominant fashion in cell-cell hybridization studies. Also, the enhanced enzyme activity in the drug-resistant cells was observed only during the cell cycle S phase of synchronized cells. The properties of these drug-resistant lines indicate that they will be useful for genetic and biochemical studies.
Insights
Hydroxyurea resistance in Chinese hamster ovary cells decreased over time without selective pressure. Drug-sensitive ribonucleotide reductase levels correlated with reduced hydroxyurea resistance, useful for genetic studies.
Area of Science:
- Cell Biology
- Biochemistry
- Genetics
Background:
- Hydroxyurea is a cytotoxic agent used in cancer therapy.
- Understanding drug resistance mechanisms is crucial for improving treatment efficacy.
- Chinese hamster ovary (CHO) cells are a widely used model system in toxicology and genetics.
Purpose of the Study:
- To investigate the mechanisms of hydroxyurea resistance in CHO cells.
- To characterize the properties of hydroxyurea-resistant cell lines.
- To assess the utility of these cell lines for genetic and biochemical studies.
Main Methods:
- Serial cultivation of hydroxyurea-resistant CHO cells without selective agent.
- Isolation and characterization of stable subclones with varying drug sensitivities.
- Measurement of intracellular ribonucleotide reductase levels.
- Cell-cell hybridization studies.
- Analysis of enzyme activity during the cell cycle.
Main Results:
- Cells with decreased hydroxyurea resistance accumulated upon serial cultivation.
- Three subclones exhibited differing drug sensitivities correlating with intracellular ribonucleotide reductase levels.
- Hydroxyurea resistance was expressed codominantly in cell hybrids.
- Enhanced enzyme activity was observed specifically during the S phase of synchronized cells.
Conclusions:
- A novel class of hydroxyurea resistance, linked to drug-sensitive ribonucleotide reductase, was identified.
- These resistant cell lines offer valuable tools for genetic and biochemical investigations of drug resistance.
- The cell cycle-dependent enzyme activity provides insights into the regulation of hydroxyurea resistance.
