Inhibition of N-nitrosomethylbenzylamine-induced tumorigenesis in the rat esophagus by dietary freeze-dried strawberries.

Abstract

In the present study, we examined the ability of dietary freeze-dried strawberries to inhibit N-nitrosomethylbenzylamine (NMBA)-induced tumorigenesis in the rat esophagus. Initially, we conducted a bioassay to determine the effects of dietary freeze-dried strawberries on esophageal tumor development. Two weeks prior to NMBA treatment, animals were placed on a control diet or diets containing 5 and 10% freeze-dried strawberries. NMBA treatment was once per week for 15 weeks. At 30 weeks, 5 and 10% freeze-dried strawberries in the diet caused significant reductions in esophageal tumor multiplicity of 24 and 56%, respectively. Based on these results, we conducted studies to determine potential mechanisms by which freeze-dried strawberries inhibit tumorigenesis. In a short-term bioassay, we evaluated the effects of dietary freeze-dried strawberries on the formation of O6-methylguanine in the rat esophagus. Animals were placed on control diet or diets containing 5 and 10% freeze-dried strawberries for two weeks. At the end of this period, animals received a single subcutaneous dose of NMBA and were killed 24 h later. A significant decrease in O6-methylguanine levels was observed in the esophageal DNA of animals fed strawberries, suggesting that one or more components in strawberries influence the metabolism of NMBA to DNA-damaging species. Finally, in order to evaluate post-initiation effects, we conducted a study where freeze-dried strawberries were administered in the diet only following NMBA treatment. Animals were placed on control diet and dosed with NMBA three times per week for 5 weeks. Immediately following NMBA treatment, animals were placed on control diet or diets containing 5 and 10% freeze-dried strawberries. At 25 weeks, 5 and 10% freeze-dried strawberries in the diet significantly reduced tumor multiplicity by 38 and 31%, respectively. Our data suggest that dietary freeze-dried strawberries effectively inhibit NMBA-induced tumorigenesis in the rat esophagus.

• Authors: P S Carlton, L A Kresty, J C Siglin, M A Morse, J Lu, C Morgan, G D Stoner
• Journal: Carcinogenesis (Carcinogenesis) Vol. 22 Issue 3 Pg. 441-6 (Mar 2001) ISSN: 0143-3334 [Print] England
• PMID: 11238184 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Anticarcinogenic Agents
• Carcinogens
• DNA Adducts
• nitrosobenzylmethylamine
• Dimethylnitrosamine

Topics

• Animals
• Anticarcinogenic Agents
• Carcinogens (toxicity)
• DNA Adducts
• Dimethylnitrosamine (analogs & derivatives, antagonists & inhibitors, toxicity)
• Esophageal Neoplasms (chemically induced, prevention & control)
• Fruit
• Male
• Rats