Related Experiment Videos
A comparative study of the interactions of bleomycin with nuclei and purified DNA
M R Ciriolo1, J Peisach, R S Magliozzo
1Department of Molecular Pharmacology, Albert Einstein College of Medicine of Yeshiva University, Bronx, New York 10461.
Abstract:
Fe(III)-bleomycin associates strongly with rat liver nuclei and binds to nuclear DNA. Metal-free and Cu(II)-bleomycin, however, do not bind to nuclei. The treatment of nuclei with activated iron-bleomycin results in nucleic base and base propenal release from the DNA, and also gives membrane peroxidation. Isolation and quantitation of the base propenals and free bases released subsequent to activated bleomycin treatment reveal an alteration in the stoichiometry of these products compared to those released from purified DNA. With nuclei, significantly less propenal is formed, although the yield of free base is equivalent to that from purified DNA. The membrane peroxidation products from nuclei are the same as those obtained from microsomal membranes treated with activated bleomycin. Superoxide dismutase inhibits the membrane peroxidation but has no effect on the DNA breakage reactions. The results implicate a role for iron in mediating the in vivo action of bleomycin and also reveal a potentially toxic effect, membrane peroxidation, separate from DNA damage.
Insights
Iron-bleomycin damages DNA and causes membrane peroxidation in liver nuclei. This iron-mediated damage, distinct from DNA breakage, highlights bleomycin
Area of Science:
- Biochemistry
- Molecular Biology
- Toxicology
Background:
- Bleomycin is an anticancer drug that induces DNA damage.
- The role of iron in bleomycin's mechanism of action and potential side effects is not fully understood.
Purpose of the Study:
- To investigate the interaction of iron-bleomycin with rat liver nuclei and its effects on DNA and cellular membranes.
- To differentiate bleomycin-induced DNA damage from other toxic effects.
Main Methods:
- Treatment of isolated rat liver nuclei and purified DNA with activated iron-bleomycin.
- Quantitation of released nucleic bases and base propenals.
- Analysis of membrane peroxidation products.
- Assessment of superoxide dismutase's effect on peroxidation and DNA breakage.
Main Results:
- Fe(III)-bleomycin binds to liver nuclei and DNA, causing DNA base and base propenal release.
- Nuclei treatment yields less propenal but equivalent free base compared to purified DNA.
- Activated iron-bleomycin induces membrane peroxidation in nuclei and microsomal membranes.
- Superoxide dismutase inhibits membrane peroxidation but not DNA breakage.
Conclusions:
- Iron is crucial for mediating bleomycin's in vivo effects on DNA.
- Bleomycin can cause membrane peroxidation, a toxic effect separate from DNA damage.
- These findings elucidate bleomycin's complex mechanism and potential toxicity.