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Quercetin does not significantly affect the protection of a fish oil diet in early colon carcinogenesis
Author(s) -
Paulhill K J,
Taddeo S S,
Carroll R J,
Chapkin R S,
Lupton J R,
Turner N D
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a58-b
Subject(s) - fish oil , antioxidant , catalase , reactive oxygen species , superoxide dismutase , apoptosis , corn oil , polyunsaturated fatty acid , chemistry , tunel assay , endogeny , endocrinology , oxidative stress , medicine , biochemistry , biology , food science , fatty acid , fish <actinopterygii> , fishery
Quercetin (Q) may protect against colon cancer due to its antioxidant activity. In contrast, we have shown that a fish oil diet (FO; n‐3 fatty acids), compared to corn oil (CO; n‐6 fatty acids), protects against colon cancer by decreasing endogenous antioxidant activities leading to increased reactive oxygen species (ROS), an inducer of apoptosis. We hypothesized that adding an antioxidant to a pro‐oxidant diet could negate the protective effect of FO by counteracting FO effects on colonocyte redox status. To test this, we provided 40 rats with FO or CO (fiber = pectin) diets supplemented with 0 or 0.45% Q for 10 wk. All rats were injected with AOM on d 21 and 28. Aberrant crypts (AC) (marker for colon cancer) and apoptosis (TUNEL) were measured. Catalase (CAT) and Mn superoxide dismutase (SOD) activity were indicators of endogenous antioxidant capacity. AC numbers were lower (p=0.0001) in FO vs CO rats, but AC tended to increase (P<0.098) for FO diets containing Q. Surprisingly, dietary lipid did not affect apoptosis, yet apoptosis was elevated (P=0.0002) by Q for FO and CO diets. CAT activity was higher (p=0.0204) in FO vs CO rats, however, Q lowered (P=0.068) CAT activity in FO rats. SOD activity was not affected by diet. Despite increasing apoptosis, Q did not lower AC formation. The small increase in AC caused by Q in the FO diet may result from the lower CAT activity caused by the combination. The long‐term consequences of supplementing antioxidants to a diet thought to exert its anticancer effect through a pro‐oxidant mechanism are unknown and deserve further study. Funding: USDA‐CSREES 2005‐34402‐16401, NIEHS P30‐ES09106.