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Modification by catechol and resorcinol of upper digestive tract carcinogenesis in rats treated with
S Yamaguchi1, M Hirose, S Fukushima
1First Department of Pathology, Nagoya City University, Medical School, Japan.
Abstract:
Modifying effects of the environmental contaminant catechol, and its isomers resorcinol and hydroquinone, on methyl-N-amylnitrosamine (MNAN)-induced carcinogenesis were studied in male F344 rats. Groups of 15 rats were given three i.p. injections of 25 mg/kg of body weight of MNAN within the initial 2-wk period, and commencing 1 wk thereafter they were administered 0.8% catechol, 0.8% resorcinol, or 0.8% hydroquinone in powdered basal diet or were given basal diet alone for 49 wk. Additional groups of 10 to 15 rats were similarly treated without prior carcinogen exposure. Histological examination after sacrifice at wk 52 revealed that the incidences of tongue papillomas and esophageal squamous cell carcinomas in the groups given MNAN followed by catechol (57.1% and 64.3%) or resorcinol (50% and 58.8%) were significantly higher than those in the carcinogen only controls (9.1, and 0%, respectively). Hydroquinone also enhanced the development of esophageal squamous cell carcinomas but was less active than catechol or resorcinol. The incidence of alveolar hyperplasia in the lungs of the group given MNAN followed by catechol (0%) was, in contrast, significantly reduced as compared to the control value (54.5%). Hydroquinone and resorcinol showed a similar but non-significant tendency. These results indicated that the environmental contaminant, catechol and its isomers, may play a role in the development of human upper gastrointestinal cancer, in addition to exerting modifying effects in other organs.
Insights
Environmental contaminants catechol and its isomers significantly increased upper gastrointestinal tumors in rats exposed to methyl-N-amylnitrosamine (MNAN). These compounds may influence human cancer development and affect other organs.
Area of Science:
- Toxicology
- Carcinogenesis
- Environmental Health
Background:
- Environmental contaminants can modify carcinogen-induced effects.
- Catechol, resorcinol, and hydroquinone are common environmental contaminants.
Purpose of the Study:
- To investigate the modifying effects of catechol and its isomers on methyl-N-amylnitrosamine (MNAN)-induced carcinogenesis in rats.
- To assess the role of these contaminants in upper gastrointestinal cancer development.
Main Methods:
- Male F344 rats were administered methyl-N-amylnitrosamine (MNAN) via intraperitoneal injection.
- Following MNAN exposure, rats received diets containing catechol, resorcinol, or hydroquinone for 49 weeks.
- Tumor incidence and histological changes were examined after 52 weeks.
Main Results:
- Catechol and resorcinol significantly increased the incidence of tongue papillomas and esophageal squamous cell carcinomas compared to MNAN-only controls.
- Hydroquinone also enhanced esophageal tumors, though to a lesser extent.
- Catechol significantly reduced lung alveolar hyperplasia, while hydroquinone and resorcinol showed a similar non-significant trend.
Conclusions:
- Catechol and its isomers can act as promoters in MNAN-induced carcinogenesis, particularly in the upper gastrointestinal tract.
- These findings suggest a potential role for environmental contaminants like catechol in human upper gastrointestinal cancer.
- The study also highlights modifying effects on other organs, such as the lungs.