BOSTONLycopene, the carotenoid that gives tomatoes their vivid red color, may act as a chemopreventive agent against certain types of cancer. Nonalcoholic steatohepatitis (NASH) is a liver disease that occurs in subjects without a history of alcohol abuse. Researchers at Tufts University investigated the efficacy of an equivalent dosage of dietary lycopene from either a pure compound or a tomato extract (TE) against NASH-promoted hepatocarcinogenesis (Int J Cancer. 2010;126(8):1788-96). Six groups of rats were injected with diethylnitrosamine (DEN) and then fed either Lieber-DeCarli control diet or high-fat diet (HFD) with or without lycopene or TE for six weeks.
Results showed both lycopene and TE supplementations significantly decreased the number of altered hepatic foci expressing the placental form of glutathione S-transferase in the livers of HFD-fed rats. This was associated with significantly lower proliferating cell nuclear antigen positive hepatocytes and cyclinD1 protein, as well as decreased activation of extracellular signal-regulated kinase and nuclear NF-kappaB. Although both lycopene and TE supplementations reduced HFD-induced lipid peroxidation in the livers, researchers observed significantly decreased cytochrome P450 2E1, inflammatory foci and mRNA expression of proinflammatory cytokines (TNF-alpha, IL-1beta and IL-12) in the HFD+TE fed group, but increased nuclear NF-E2-related factor-2 and heme oxygenase-1 proteins in the HFD+lycopene fed group, relative to HFD feeding alone. Data indicated lycopene and TE can inhibit NASH-promoted hepatocarcinogenesis mainly as a result of reduced oxidative stress, which could be fulfilled through different mechanisms.