Effects of grape syrup in colorectal cancer: study in Wistar rats

Abstract

Colorectal cancer is the third cause of cancer in the world, in both sexes, and the second leading cause in developed countries. Malnutrition in cancer patients is a frequent complication as a result of cytokine production by the tumor and surgical treatments, chemotherapy and/or radiotherapy. The preventive treatment, directed to the consumption of foods that have antineoplastic properties, may assist in reducing these rates. The grape is a fruit widely investigated in the prevention of cardiovascular disease and recently in cancer research. The amount of phenolics present in grapes has multiple biological effects such as antioxidant, anti-inflammatory antimicrobial and anticarcinogenic activities. Resveratrol, one of the substances present in this fruit, has anti-inflammatory properties and may act to inhibit production of COX-2. This situation leads us to an investigation to detect the effectiveness of grape syrup in colorectal cancer, dysplasia and cancer already present. The intent of this experimental research is to show the effectiveness of possible properties existing in grape in colorectal cancer. Objective: To evaluate the effects of grape syrup on colon cancer induced in Wistar rats, by studying the oxidative modification of DNA and expression of Cox-2. Methods: Wistar male rats (n= 50) aged 8-10 weeks weighing approximately 250-300g were divided into five groups (n = 10 animals each), where the SHAM control group will receive saline. In the experimental group all animals will receive azoxymethane (AOM) 15mg/kg body weight once a week for two weeks and divided into three groups: G-O2 that after receiving AOM will not receive treatment, G-03: that 1 week after the last application of AOM will be treated with grape syrup 1% every two days, G-04: after 1 week of the last application of AOM will be treated with 2% grape syrup every two days and the G-05 will be treated with the grape syrup 2% without treatment with AOM. Normal and damaged mucosa will be subjected to the comet assay (analysis by single cell gel) in order to evaluate and detect DNA damage. The expression of COX-2 will be studied by immunohistochemistry and gene expression, the response evaluation will be semi-quantitative and the results will be measured by a scoring system based on intensity and percentage of positive cells. (AU)