Abstract: Objective The of this study was to investigate the effect of lycopene(LP)on the proliferation and apoptosis of human osteosarcoma MG-63 cells and to explore its mechanism.Methods MG-63 cells in the logarithmic growth phase were treated with LP(5,10 and 20μg/mL)or Cisplatin(40μg/mL)for 48h.No LP or Ciplatin treatment was as the control group.The cell growth status was observed and the cell proliferation was measured by MTT colorimetric assay.Flow cytometry(FCM)was used to detect the cell cycle and apoptosis of MG-63 cells and the apoptotic rate was calculated in this study.Reverse transcription-polymerase chain reaction(RT-PCR)was used to measure mRNA levels of Bax and bcl-2,and calculate the ratio of Bax/bcl-2 in MG-63 cells.Western blot also was used to examine the expression of caspase-3 protein in MG-63 cells.Results MG-63 cells were adherent and proliferated rapidly in the control group.The cells in LP treated groups showed that the cell proliferation was inhibited and the number of cells was significantly decreased,with retraction and detaching.The inhibitory rate of MG-63 cells in LP treated group were significantly increased when compared to the control group.LP significantly prolonged the cell cycle at the G₀/G₁ phase and shortened the cell cycle at the S and G₂/M phase.LP also significantly increased the apoptosis rate,up-regulated the mRNA level of Bax,down-regulated the mRNA level of bcl-2,increased the ratio of Bax/bcl-2 and the expression of caspase-3 protein in MG-63 cells(P＜0.05 or P＜0.01).Conclusion LP may effectively inhibit the proliferation of MG-63 cells and promote the apoptosis.The mechanism may be related to the cell cycle and the regulation of apoptosis and gene expression.

Key words: Lycopene, Osteosarcoma, Proliferation, Apoptosis, Caspase-3