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Gene-specific DNA interstrand cross-links produced by nitrogen mustard in the human tumor cell line Colo320HSR
B W Futscher1, R O Pieper, W S Dalton
1Department of Pharmacology, Stritch School of Medicine, Loyola University Chicago, Maywood, Illinois 60153.
Abstract:
Genomic and gene-specific DNA interstrand cross-links produced by nitrogen mustard (HN2) were measured in the human tumor cell line Colo320HSR. Following exposures that produced greater than or equal to 1 log cell kill, it was found that HN2-induced DNA interstrand cross-links were produced and processed in a heterogeneous fashion within the genome. Cross-links were detected in the amplified, overexpressed c-myc oncogene, whereas in the weakly expressed N-ras gene and the nontranscribed, high copy number alpha-satellite sequence (of chromosome 20), cross-links were not detected. The cross-links in the c-myc oncogene disappeared more rapidly than total genomic cross-links. These results suggest that HN2-induced DNA interstrand cross-links are produced and processed in the genome in a nonrandom fashion.
Insights
Nitrogen mustard (HN2) creates DNA interstrand cross-links unevenly across the genome. These cross-links are found in active genes like c-myc but not in inactive sequences, suggesting non-random DNA damage and repair.
Area of Science:
- Molecular Biology
- Genomics
- Cancer Research
Background:
- Nitrogen mustard (HN2) is a chemotherapeutic agent that induces DNA interstrand cross-links.
- Understanding the distribution and processing of these cross-links is crucial for cancer therapy.
Purpose of the Study:
- To investigate the genomic and gene-specific distribution of HN2-induced DNA interstrand cross-links.
- To determine if DNA cross-linking by HN2 occurs randomly or in a non-random fashion within the genome.
Main Methods:
- Exposure of the human tumor cell line Colo320HSR to HN2.
- Quantification of genomic and gene-specific DNA interstrand cross-links.
- Analysis of cross-linking in the c-myc oncogene, N-ras gene, and alpha-satellite sequences.
Main Results:
- HN2-induced DNA interstrand cross-links were heterogeneously distributed within the genome.
- Cross-links were detected in the amplified, overexpressed c-myc oncogene.
- Cross-links were not detected in the weakly expressed N-ras gene or the nontranscribed alpha-satellite sequence.
- Cross-links in the c-myc oncogene were resolved more rapidly than total genomic cross-links.
Conclusions:
- HN2-induced DNA interstrand cross-links are produced and processed in a non-random manner within the genome.
- Gene activity and accessibility may influence the site and persistence of DNA cross-linking by HN2.