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Daunomycin modifies the sequence-selective recognition of DNA by actinomycin
G S Ridge1, C Bailly, D E Graves
1Department of Pharmacology, University of Cambridge, UK.
Nucleic Acids Research
|December 11, 1994
Summary
Daunomycin alters how the antitumour drug actinomycin D binds to DNA. This drug interaction may explain the increased toxicity observed when these two drugs are used together in cancer therapy.
Area of Science:
- Biochemistry
- Molecular Biology
- Pharmacology
Background:
- Actinomycin D typically binds to DNA at CpG sites.
- Daunomycin's effect on actinomycin D binding, particularly to AT regions, is not well understood.
- Combination chemotherapy with these agents can lead to increased toxicity.
Purpose of the Study:
- To investigate the effect of daunomycin on actinomycin D's DNA binding.
- To determine if daunomycin causes actinomycin D to bind to AT regions.
Main Methods:
- Used a photoreactive 7-azido derivative of actinomycin D.
- Studied binding to three different DNA fragments in the presence and absence of daunomycin.
Main Results:
- Daunomycin altered actinomycin D's DNA binding.
- Actinomycin D was displaced from primary GpC sites to secondary sites on the DNA.
- Displacement was not specifically towards AT regions.
Conclusions:
- Daunomycin influences actinomycin D's DNA binding preferences.
- This altered binding mechanism provides a potential explanation for the enhanced toxicity of combined actinomycin D and daunomycin therapy.