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Laser Microirradiation to Study In Vivo Cellular Responses to Simple and Complex DNA Damage
Published on: January 31, 2018
Enediyne-mediated DNA damage in nuclei is modulated at the level of the nucleosome
L Yu1, I H Goldberg, P C Dedon
1Division of Toxicology, Massachusetts Institute of Technology, Cambridge 02139.
Abstract:
DNA damage in HeLa nuclei and isolated nucleosome core particles has been examined for several members of the enediyne family of antitumor antibiotics: calicheamicin gamma 1I (CAL), esperamicin A1 (ESP A1), esperamicin C (ESP C), and neocarzinostatin (NCS). In nuclei, both NCS and ESP A1 produced DNA damage limited to the linker region of the nucleosome, while CAL and ESP C, an analog of ESP A1 missing the deoxyfucose-anthranilate moiety, damaged both the core and linker DNA. DNA fragments produced by CAL and ESP C in the nucleosome core occurred with a 10-11-nucleotide periodicity similar to that produced by DNase I, while damage produced by NCS and ESP A1 appeared to be limited to the terminal portions of the core DNA. The damage in nuclei is shown to be caused directly by the drugs with little contribution from endogenous factors, such as nucleases and topoisomerases. Features of drug structure that may limit damage to the nucleosome core include the presence of substituents on both sides of the CAL/ESP-type core, and the presence of an intercalating moiety, such as the naphthoate of NCS and possibly the anthranilate of ESP A1.
Insights
Enediyne antitumor antibiotics calicheamicin gamma 1I (CAL) and esperamicin C (ESP C) damage both core and linker DNA in nucleosomes. Neocarzinostatin (NCS) and esperamicin A1 (ESP A1) primarily damage linker DNA.
Area of Science:
- Molecular Biology
- Biochemistry
- Pharmacology
Background:
- Enediyne antibiotics are potent DNA-damaging agents used in cancer therapy.
- Understanding their interaction with nucleosomes is crucial for drug development.
Purpose of the Study:
- To investigate the DNA-damaging patterns of enediyne antibiotics within nucleosomes.
- To correlate drug structure with DNA damage localization.
Main Methods:
- Treatment of HeLa nuclei and isolated nucleosome core particles with CAL, ESP A1, ESP C, and NCS.
- Analysis of DNA fragmentation patterns using gel electrophoresis.
- Comparison of drug-induced damage with DNase I digestion.
Main Results:
- CAL and ESP C damaged both nucleosomal core and linker DNA, with a 10-11 nucleotide periodicity in the core.
- NCS and ESP A1 predominantly damaged linker DNA and terminal core DNA.
- Drug-induced damage was direct, with minimal contribution from endogenous nucleases.
Conclusions:
- Enediyne antibiotic DNA damage patterns vary based on drug structure and substituents.
- Structural features like substituents and intercalating moieties influence DNA targeting within nucleosomes.
- These findings provide insights into the mechanism of action for enediyne-based chemotherapeutics.
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