Olive oil prevents benzo(a)pyrene [B(a)P]-induced colon carcinogenesis through altered B(a)P metabolism and decreased oxidative damage in Apc(Min) mouse model

Abstract

Colon cancer ranks third in cancer-related mortalities in the United States. Many studies have investigated factors that contribute to colon cancer in which dietary and environmental factors have been shown to play an integral role in the etiology of this disease. Specifically, human dietary intake of environmental carcinogens such as polycyclic aromatic hydrocarbons has generated interest in looking at how it exerts its effects in gastrointestinal carcinogenesis. Therefore, the objective of this study was to investigate the preventative effects of olive oil on benzo(a)pyrene [B(a)P]-induced colon carcinogenesis in adult Apc(Min) mice. Mice were assigned to a control (n=8) or treatment group (n=8) consisting of 25, 50 and 100-μg B(a)P/kg body weight (bw) dissolved in tricaprylin [B(a)P-only group] or olive oil daily via oral gavage for 60 days. Our studies showed that Apc(Min) mice exposed to B(a)P developed a significantly higher number (P<0.05) of larger dysplastic adenomas compared to those exposed to B(a)P + olive oil. Treatment of mice with B(a)P and olive oil significantly altered (P<0.05) the expression of drug-metabolizing enzymes in both the colon and liver tissues. However, only GST activity was significantly higher (P<0.05) in the liver of mice treated with 50- and 100-μg B(a)P/kg bw + olive oil. Lastly, olive oil promoted rapid detoxification of B(a)P by decreasing its organic metabolite concentrations and also decreasing the extent of DNA damage to colon and liver tissues (P<0.05). These results suggest that olive oil has a protective effect against B(a)P-induced colon tumors.

Keywords: Apc(Min) mouse; Benzo(a)pyrene; Colon cancer; Drug-metabolizing enzymes; Olive oil; Oxidative DNA damage; Polycyclic aromatic hydrocarbons.