Effects of lycopene on the growth of lung cancer cells in vitro and lung cancer in nude mice

Objective To investigate the effects of lycopene (LP) on the proliferation, apoptosis of human non-small cell lung cancer A549 cells in vitro and transplanted tumor growth in lung cancer-bearing nude mice. Methods Cell experiments in vitro: the A549 cells were cultured in vitro and the cells in logarithmic growth phase were grouped into blank group (culture medium), LP (5, 10, 20 mg/L) groups and cisplatin (40 mg/L) group, n=10.48 h after drug intewention, the cell morphology and apoptosis were observed; the cell cycle and the cellular growth inhibition rate were detected.Animal experiments in vivo: the nude mice models bearing lung cancer were made by injecting inoculation human lung cell line A549 at right groin area and grouped into model group, LP [5, 10, 20 mg/(kg·d)] groups and cisplatin 2 mg/(kg·d) group.The inhibition rate was calculated; the histopathological changes and the tumor cells apoptosis were observed, the expression of B-cell lymphoma/leukemia-2 (Bcl-2), Bax, cleved caspase-3 were detected. Results Cell experiments in vitro: The A549 cells in blank group showed adherent growth and proliferation rapidly, while the cells in LP groups and cisplatin group showed that the proliferation was inhibited, the cell number was significantly reduced, and showing retraction, loose and off phenomenon.Compared with blank group, the morphological of LP groups was abnormalities, the percent in G0-G1 phase of cell cycle were increased, the cellular growth inhibition rate in LP groups and cisplatin group were significantly increased, the apoptosis rate was significantly increased (all P<0.05). Animal experiments in vivo: Compared with model group, the inhibition rate of 10, 20 mg/(kg·d) LP were significantly increased; necrosis presentation, tumor cell shrinkage and other pathological morphological changes appeared in 10, 20 mg/(kg·d) LP groups; the expression of Bcl-2 was significantly decreased, the expression of Bax was significantly increased, the ratio of Bax/Bcl-2 were significantly increased, the expression of cleved caspase-3 protein were significantly increased; all of the difference above were significant (P<0.05). Conclusions LP can effectively inhibit the growth of lung cancer cells in vitro and the growth of transplanted tumor in vivo, which perhaps related to its effects of altering the lung cancer cell cycle and promoting lung cancer cell apoptosis. Key words: Lycopene; Lung cancer; Cell cycle; Growth inhibition rate; Apoptosis