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Alteration of chromatin structure induced by the binding of adriamycin, daunorubicin and ethidium bromide
Abstract:
The results reported in this paper show the changes in chromatin structure caused by the binding of adriamycin (ADR), daunorubicin (DR) and ethidium bromide (EtdBr) to DNA in chromatin, either isolated or in nuclei or whole cells. Micrococcal nuclease was used as the structural probe of chromatin. The binding of the drugs to chromatin DNA induced two structural changes. First, it produced an unfolding of the overall chromatin structure as evidenced by the increased production of acid-soluble oligonucleotides for the drug-treated samples above the level of the control sample. Second, it caused a disruption of the core particle structure with increased production of DNA of subnucleosomal size and smearing of the nucleosome pattern. The effects were greatest for duanorubicin, followed by adriamycin and ethidium bromide.
Insights
Adriamycin, daunorubicin, and ethidium bromide alter chromatin structure by causing unfolding and disrupting core particles. Daunorubicin showed the most significant impact on DNA organization.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Chromatin, the complex of DNA and proteins, dictates DNA accessibility and gene regulation.
- Intercalating agents and DNA-binding drugs can alter DNA and chromatin structure.
- Understanding drug-induced structural changes is crucial for pharmacology and molecular biology.
Purpose of the Study:
- To investigate the structural modifications in chromatin induced by adriamycin (ADR), daunorubicin (DR), and ethidium bromide (EtdBr).
- To compare the effects of these three drugs on DNA organization within isolated chromatin, nuclei, and whole cells.
Main Methods:
- Chromatin structural analysis using micrococcal nuclease as a probe.
- Treatment of isolated chromatin, nuclei, and whole cells with ADR, DR, and EtdBr.
- Quantification of acid-soluble oligonucleotides and subnucleosomal DNA fragments to assess structural changes.
Main Results:
- Drug binding induced chromatin unfolding, evidenced by increased acid-soluble oligonucleotides.
- Core particle structure disruption occurred, leading to subnucleosomal DNA fragments and altered nucleosome patterns.
- Daunorubicin exhibited the most potent effects, followed by adriamycin, and then ethidium bromide.
Conclusions:
- Adriamycin, daunorubicin, and ethidium bromide significantly alter chromatin higher-order structure.
- The drugs cause both global chromatin unfolding and specific disruption of nucleosome core particles.
- Drug-induced structural changes vary in magnitude, with daunorubicin being the most disruptive.