Effect of lycopene isolated from Chlorella marina on proliferation and apoptosis in human prostate cancer cell line PC-3

Even though the role of lycopene from tomato (trans form) in controlling prostate cancer was reported, lycopene (cis and trans 60:40) isolated from green algae Chlorella marina was not reported so far. The present study aimed to assess the anti-proliferative and apoptotic effect of lycopene from a new source and to compare the activity with available trans lycopene by using androgen-independent human prostate cancer cell lines. Exposure of PC-3 and DU-145 cell lines to algal lycopene (AL) at a dose of 20 and 50 mu M significantly inhibited the growth and colony formation, and the percentage of inhibition was higher than tomatal lycopene (TL)-treated groups. The stability of AL in cell culture medium was high, when compared to TL under standard cell culture conditions. The level of lycopene was not detected in PC-3 cell lines cultured in medium lacking lycopene. Staining cells with acridine orange and ethidium bromide, the PC-3 control cells showed largely non-fragmented intact nucleoid. Stronger apoptosis signal was induced with higher concentrations (50 mu M) of algal lycopene. Increased DNA damage was observed in AL- and TL-treated cells which appear as comet during single-cell gel electrophoresis. Flow cytometry results revealed that AL caused PC-3 cells to accumulate in the G(0)/G(1) phase and to undergo apoptosis. The effect was higher in AL groups than TL-treated groups. Algal lycopene showed very significant anti-proliferative and apoptotic effect in human prostate cancer cell lines. Therefore, algal lycopene from C.marina would be recommended for the treatment of prostate cancer.