The effect of lycopene on cell growth and oxidative DNA damage of Hep3B human hepatoma cells

Lycopene, the predominant carotenoid in tomatoes and tomato- based foods, is reported to protect against various cancers, especially prostate cancer. We investigated the effect of lycopene on DNA damage and cell growth inhibition in the Hep3B human hepatoma cell line. Lycopene was analyzed by HPLC, and cell proliferation was determined by 3-( 4,5dimethylthiazolyl- 2)- 2,5- diphenyltetrazolium bromide ( MTT) assay. A final lycopene concentration of 0.1 - 50 mu M was added to cells plated in 96- well plates. After a 24- hr incubation, cell viability was measured as absorbance at 570 nm after the MTT assay. The effects of lycopene on cell cycle progression were investigated with flow cytometry. Lycopene induced G0/ G1 arrest and S phase block. Oxidative DNA damage was determined by the Comet ( single- cell gel electrophoresis) assay. Lycopene inhibited cell growth in a dose- dependent manner. Cell growth was inhibited 20% at 0.2 mu M lycopene and 40% at 50 M lycopene after a 24- hr incubation. In the Comet assay, lycopene- treated cells showed less DNA damage than did placebo- treated cells. The inhibition of Hep3B cell growth in this study demonstrates the antitumor properties of lycopene.