Evaluating the effect of lycopene on telomerase activity in the human leukemia cell line K562

Telomerase has been proposed as a novel and potentially selective target in cancer therapy. Many plant-derived products can induce apoptosis via telomerase inhibition. Lycopene (a carotenoid pigment) has been found to exhibit the various biological effects on different types of cancer cells, but its effect on telomerase activity has not been investigated. Therefore, this study aimed to examine the apoptosis-inducing effect of lycopene on human leukemia cell line K562, with particular emphasis on its effect on telomerase inhibition. Anti-proliferative effect of lycopene at different doses (0-20µm) and time intervals (24-72 h) on K562 cells was evaluated using the 3-(4, 5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. To measure apoptosis, the Hoechst 33342 staining method and flow cytometry were used. The telomerase activity was determined using the telomeric repeat amplification protocol (TRAP) and ELISA assay. The treatment of the K562 cells with lycopene dose-dependently resulted in a significant inhibition of cell growth and telomerase activity compared to the untreated cells. Furthermore, a positive correlation was found between telomerase inhibition and the induction of apoptosis in lycopene-treated K562 cells. The results of this study suggest a novel mechanism in the anti-cancer activity of lycopene in human leukemia K562 cells and may provide a basis for the future development of anti-telomerase agents.