Effect of Lycopene on IGF-I, IGF Binding Protein-3 and IGF Type-I Receptor in Prostate Cancer Cells

Prostate cancer is the second most common cancer that leads to death in elderly men. The risk of prostate cancer prevalence is often associated with elevated level of insulin-like growth factor I (IGF-I) and decreased level of IGF-binding protein 3 (IGFBP-3). Lycopene, a carotenoid, reduces the proliferation of cancer cells and, thus, induces apoptosis. Hence, higher intake of lycopene can be associated with a lower risk of prostate cancer. However, the mechanism of action of lycopene in prostate cancer is still unclear. The present study was carried out to find the effects of lycopene on the components of IGF system and apoptosis in an androgen-independent prostate cancer cell (PC-3). PC-3 cells were treated with various concentrations of lycopene, 20, 40 and 60 μM, each for 24, 48, 72 and 96 h, IGF-1, IGFBP-3 and IGF-I receptor (IGF-IR) levels and indication of apoptosis were evaluated. The proliferation of lycopene-treated PC-3 cells decreased significantly. At a concentration of 40 μM lycopene treatment significantly increased the level of IGFBP-3. Lycopene-induced apoptosis was indicated in annexin V and PI binding. Lycopene-induced DNA fragmentation was not detectable after 24 h after the treatment whereas the same was observed after 48 h treatment. There was a significant decrease in the IGF-IR expression after the cells were treated with lycopene and IGF-I. The data obtained suggest that the components of the IGF system may act as a positive regulator for lycopene-induced apoptosis in PC-3 cells. The results obtained are encouraging and may lead to the development of lycopene as a potential therapy for prostate cancer.