There are two main anticancer effects of lycopene: oxidative mechanism and non-oxidative mechanism.
1. Oxidative
Lycopene is the most potent antioxidant among common carotenoids in the oxidative mechanism. It inhibits singlet oxygen (1O2) and scavenges nitrogen dioxide radicals (NO2·), sulfur-based radicals (RS·) and sulfonyl radicals (RSO·2 ). During singlet oxygen quenching, energy is transferred from 1O2 to the lycopene molecule, transforming into an energy-rich triplet state.
Capture other ROS, NO2· or peroxynitrite, resulting in the oxidative decomposition of lycopene molecules.
Therefore, lycopene can protect the body from oxidation of lipids, proteins and DNA in vivo.
2. Non-oxidative
In a non-oxidative mechanism, lycopene inhibits the phosphorylation of carcinogens on regulatory proteins, such as the p53 and Rb anti-cancer genes. It stops cell division during the quiescent cell phase of the cell cycle to the prophase of DNA synthesis.
Lycopene-induced regulation of cytochrome P4502E1 by hepatic metabolic enzymes is a potential mechanism for protection from carcinogen-induced preneoplastic lesions in rat liver. Lycopene effectively reduces cell proliferation induced by insulin growth factor, a potent mitogen in various cancer cell lines.
Summary
Consumption of tomatoes and their products or circulating levels of lycopene are inversely associated with cancer risk, especially breast, colon, lung and prostate cancers.