Many in-vitro studies using cultured prostate cancer cells suggest that lycopene could be used as a drug for the treatment of prostate cancer. An Indian study by University of Madras showed that lycopene reduced cell growth and induced apoptosis of PC-3 prostate cancer cells [1]. Kanagaraj and co-workers mainly looked at the influence of lycopene on the insulin-like growth factor-I system and found that lycopene significantly increased the level of IGF-binding protein 3. This protein has been shown to inhibit the proliferation of prostate cancer cells by a signaling pathway independent of IGF.
Gunasekera and his co-workers also found that lycopene inhibited prostate cancer cell proliferation in a laboratory experiment [4]. They tested the effect of lycopene derived from grapefruit and commercial lycopene on cultured prostate cancer cells (androgen-independent and androgen-responsive). Lycopene inhibited the growth of the prostate cancer cells in a concentration and time-dependent manner but had no such effect on non-malignant prostate cancer cells. Liu et al investigated the preventive mechanisms of lycopene in prostate cancer. They found that lycopene reversed dihydrotestosterone effects of prostate cancer cells on the death of normal human prostate epithelial cells, decreased production of IGF-I by prostate cancer cells and inhibited IGF-I stimulated growth of normal prostate epithelial cells. They suggested that lycopene probably acted by attenuating phosphorylation of protein kinases [2].
Lycopene induces apoptosis in cultured prostate cancer cells, inhibits cell proliferation. Lycopene also changes the cell cycle distribution by increasing the proportion of G0/G1 phase and decreasing the proportion of S and G2/M phase. It downregulates the expression of cyclin D1 and upregulates the expression of Bax, a protein that promotes apoptosis. Overexpression of cyclin D1 is important in the development of many cancers including breast, prostate and colon cancers [3].
A Canadian in-vitro study lead by Ivanov of the Prostate Research Centre at Vancouver General Hospital, University of British Columbia, supported further studies about lycopene to prevent and treat prostate cancer. Ivanov and co-workers tested the effect of lycopene on the growth and survival of androgen-responsive and androgen-independent prostate cancer cells. They found that lycopene stopped cancer cell growth of both cell types by inducing G0/G1 cell cycle arrest. Only the androgen-responsive cells underwent apoptosis [5].
[1] Kanagaraj P, Vijayababu MR, Ravisankar B, Anbalagan J, Aruldhas MM, Arunakaran J. "Effect of lycopene on insulin-like growth factor-I, IGF binding protein-3 and IGF type-I receptor in prostate cancer cells. " J Cancer Res Clin Oncol. 2007 Jun;133(6):351-9.
[2] Liu X, Allen JD, Arnold JT, Blackman MR. "Lycopene inhibits IGF-I signal transduction and growth in normal prostate epithelial cells by decreasing DHT-modulated IGF-I production in cocultured reactive stromal cells." Carcinogenesis. 2008 Feb 17.
[3] Wang A, Zhang L. " Effect of lycopene on proliferation and cell cycle of hormone refractory prostate cancer PC-3 cell line." Wei Sheng Yan Jiu. 2007 Sep;36(5):575-8.
[4] Gunasekera RS, Sewgobind K, Desai S, Dunn L, Black HS, McKeehan WL, Patil B. "Lycopene and lutein inhibit proliferation in rat prostate carcinoma cells.". Nutr Cancer. 2007;58(2):171-7.
[5] Ivanov NI, Cowell SP, Brown P, Rennie PS, Guns ES, Cox ME. "Lycopene differentially induces quiescence and apoptosis in androgen-responsive and -independent prostate cancer cell lines. " Clin Nutr. 2007 Apr;26(2):252-63.
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