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Intestinal cancer induced by N-nitroso compounds
1NCI-Frederick Cancer Research Facility, BRI-Basic Research Program, Maryland 21701.
Toxicologic Pathology
|January 1, 1988
Summary
Several N-nitroso compounds cause colon tumors in rats, requiring metabolic activation. Differences in DNA alkylation and compound stability may explain varying carcinogenic effects and tumor locations.
Area of Science:
- Toxicology
- Carcinogenesis
- Organic Chemistry
Background:
- N-nitroso compounds are known carcinogens.
- Specific N-nitroso compounds induce tumors in the colon and other intestinal regions.
- The mechanism of action for these compounds involves metabolic activation.
Purpose of the Study:
- To investigate the carcinogenic potential of various N-nitroso compounds on the rat intestinal tract.
- To explore structure-activity relationships in N-nitroso compound-induced carcinogenesis.
- To identify factors influencing tumor induction sites and susceptibility.
Main Methods:
- Oral administration of various N-nitroso compounds to rats.
- Observation and documentation of tumor development in the colon and other intestinal segments.
- Comparison of carcinogenic effects between different N-nitroso compounds and sexes.
Main Results:
- Beta-oxidized n-propyl-nitrosamines, 1,2-dimethylhydrazine, azomethane, and azoxymethane are potent colon carcinogens requiring metabolic activation.
- Nitrosoalkylureas, including monoalkyl- and dialkylnitrosoureas, induced colon tumors.
- Nitrosoethylurea and nitrosohydroxyethylurea also induced tumors in the duodenum and ileum.
- Male rats exhibited higher susceptibility to intestinal tumor induction than females.
Conclusions:
- Carcinogenicity of N-nitroso compounds is influenced by their chemical structure, metabolic activation, and DNA alkylating ability.
- Compound stability and physical properties may modulate the carcinogenic process.
- Sex-based differences in susceptibility to intestinal carcinogenesis were observed.