Lycopene and Lutein Inhibit Proliferation in Rat Prostate Carcinoma Cells

Abstract

Consumption of lycopene, a carotenoid without provitamin A activity, has been associated with a lower risk of prostate and breast cancer. Lutein is another carotenoid that may be associated with a reduced risk of age-related macular degeneration, the leading cause of blindness in adults 65 years of age and older. Bioactive compounds such as lycopene and lutein, derived from natural plant sources, have been shown to act at low substrate levels through the action of intrinsic cytokines and growth factors and their receptors within tissues, particularly those of the fibroblast growth factor and transforming growth factor β families. The effects of grapefruit-derived and commercial lycopene and lutein preparations on androgen independent cultured malignant type II tumor cells [Dunning R3327AT3 or AT3 cells (androgen-responsive, slow-growing tumor cells with well developed epithelium and stroma)] were compared to their benign parent type I tumor epithelial cells (DTE). Results demonstrated that both lycopene, in an α -cyclodextrin water soluble carrier, and lutein inhibited malignant AT3 cells in a concentration and time-dependent manner. No such effect was observed when benign DTE cells were examined, demonstrating selective inhibition of extremely malignant AT3 prostate cancer cells relative to their benign parent. Lutein demonstrated a similar but slightly diminished response as lycopene. When cells were treated with cocktails of lycopene and lutein, no synergistic or additive effect occurred. These studies are consistent with epidemiological studies that show inverse relationships of these carotenoids with prostate cancer.

Acknowledgments and Notes

We thank Dr. Mikio Kan for providing FGF-1 and TGF-β, Maki Kan and Thanh Tran for their expert technical assistance, and Ms. Natachia Olivo for assistance with manuscript preparation. BSP was supported by the USDA-CSREES IFAFS#2001–52102–02294 and USDA-CSREES#2005–34402–14401 “Designing Foods for Health” through the Vegetable & Fruit Improvement Center. RSG was partially supported by University of Houston-Victoria faculty research grants.