Preventive and antiproliferative effects of tomato extracts on colorectal cancer

Colorectal cancer represents the third most common cancer and the fourth cause for cancer death in both sexes worldwide. Different epidemiological and observational evidences strictly correlated the risk of colorectal cancer to lifestyle, especially to diet. Numerous studies have investigated the effect of antioxidant substances derived from food but data on lycopene or tomato extracts are still rare. This project is based on comparing the effects of extracts (total and lipophilic fractions) obtained from fresh tomato of one tomato cultivar (corbarino) versus another tomato variety (tangerino), this latter known to have lycopene already in bioactive isoform. Using two colorectal carcinoma cell lines we previously investigated the ability of tomatoes to inhibit cancer cell growth and proliferation and hypothesized a selective action on cancer cells and a lack of an effect on non-cancer cells (normal human fibroblasts). We noticed a major effect of tangerino tomato extracts, particularly of total fraction. These data made us hypothesize a possible effect of tomato extract on cell cycle. We analyzed cell cycle progression by flow cytometry. Data obtained showed that there are not great differences between treatment and control, but we noticed different peaks in sub G0/G1 phase, suggesting a possible cellular death via apoptosis. At the molecular level, we found variation in the expression of different proteins (RBL1, RBL2, pAKT, p21cip1, p27kip1, etc) involved in different cellular mechanisms. Based on the known anti-inflammatory effect of lycopene, we also performed a western blot for IL6 and IL10 to understand if tomato extracts have an impact on the inflammation process. Data showed a reduction of IL6 and a small increase of IL10 levels, compatible with an anti-inflammatory action.