Extra-virgin olive oil-enriched diet modulates DSS-colitis-associated colon carcinogenesis in mice.

BACKGROUND & AIMS: Patients with inflammatory bowel disease (IBD) are at increased risk for developing ulcerative colitis (UC)-associated colorectal cancer (CRC). Several studies have shown that extra virgin olive oil (EVOO) might possess anti-inflammatory, antiproliferative and antiapoptotic effects. We have evaluated EVOO diet effects on the severity of repeated colitis-associated CRC.
METHODS: Six-week-old C57BL/6 mice were randomized into two dietary groups: sunflower oil (SFO) and EVOO diets, both at 10%. Mice were exposed to 15 cycles of 0.7% dextran sodium sulphate (DSS) for 1 week followed by distilled water for 10 days. After, the rats were sacrificed and colonic damage was both histologically and biochemically assessed.
RESULTS: Disease activity index (DAI) was significantly higher on SFO vs. EVOO diet at the end of the experimental period. EVOO-fed mice showed less incidence and multiplicity of tumors than in those SFO-fed mice. β-catenin immunostaining was limited to cell membranes in control groups, whereas translocation from the cell membrane to the cytoplasm and/or nucleus was showed in DSS-treated groups and its expression was higher in SFO-fed animals. Cytokine production was significantly enhanced in SFO-fed mice, while this increase was not significant in EVOO-fed mice. Conversely, cyclooxygenase-2 (COX-2) and inducible nitric oxidase synthase (iNOS) expression were significantly lower in the animal group fed with EVOO than in the SFO group.
CONCLUSIONS: These results confirm that EVOO diet has protective/preventive effect in the UC-associated CRC. This beneficial effect was correlated with a better DAI, a minor number of dysplastic lesions, a lower β-catenin immunoreactivity, a proinflammatory cytokine levels reduction, a non modification of p53 expression and, COX-2 and iNOS reduction in the colonic tissue.