Effects of Lycopene on Growth Factor Response in Prostate Cancer Cells

Dietary and nutritional factors are considered critical modulating factors in prostate cancer development. Epidemiological data have suggested to the idea that dietary consumption of lycopene, found in tomatoes, may prevent prostate cancer. This study examined the mechanism by which lycopene interacts with prostate cancer cells, with the goal of discovering less toxic treatment and prevention options. The hypothesis that was addressed was that lycopene interferes with growth factor‐mediated signal transduction in prostate cancer cells. The effects of lycopene on PC‐3, a human prostate cancer cell line, were analyzed using proliferation assays, immunoblot analysis, and confocal microscopy. The growth factors used were lysophosphatidic acid (LPA) and epidermal growth factor (EGF). Lycopene (10 μM) inhibited LPA and EGF‐induced proliferation of PC‐3 cells, confirming previous unpublished results. Lycopene also inhibited activation of Akt in response to LPA and EGF as assessed by immunoblotting. Confocal immunofluorescence microscopy showed that the decrease in activated Akt was most prominent in the cell nucleus. These results confirm the ability of lycopene to inhibit growth factor response in human prostate cancer cells, and suggest new directions for future studies.