Lycopene, a major component in tomato, exhibited potential anti-carcinogenic activity. In contrast to most organ systems, the epithelial cells of gastrointestinal tract are exposed to high concentration of lycopene. However, its effects on gastrointestinal epithelium have not been studied well. To study its mechanism of action, we investigated the effects of lycopene on proliferation in human colon cancer cells. Here, we show that lycopene inhibited cell proliferation in HT-29 cells with EC50 value of 10 microM and potently induced cell apoptosis. Treatment of HT-29 cells with lycopene caused suppression of survival signaling pathways, apoptosis and cell cycle arrest. Lycopene caused a decrease in the phosphorylation form of Akt and p27 protein. Lycopene also induced the phosphorylation of p53 and subsequently induced the expression of BAX apoptotic protein. Furthermore, lycopene suppressed the expression of COX-2 and alleviated the progression of malignant colorectal colon cancer cells. In conclusion, lycopene may inhibit the growth of colon cancer cells via suppression of PI-3K/Akt survival signaling pathways and act as a potent new anticancer compound with improved selectivity toward transformed cells.
[Proc Amer Assoc Cancer Res, Volume 47, 2006]