[Effect of lycopene on the proliferation of MCF-7 and MDA-MB-231 cells].

OBJECTIVE: To test the effect of lycopene on the proliferation and apoptosis of the estrogen receptor(ER)-positive MCF-7 and ER-negative MDA-MB-231 human breast cancer cell lines. METHODS: The cell proliferation was analyzed by the MTT and the H3-TdR incorporation. The effect of lycopene on the cell cycle and apoptosis of the synchronized cells was observed through flow cytometry. RESULTS: Lycopene inhibited the growth and DNA synthesis of both ER-positive MCF-7 and ER-negative MDA-MB-231 cells in a dose-dependent pattern. The maximum inhibition effect appeared after 4 days of exposure to lycopene, with an inhibition rate of 52.6% and 61.9% for the MCF-7 and MDA-MB-231 cells respectively. The flow cytometry analysis found more cells in the G0/G1 phase and less cells in the S and G2/M phase after 24 hours of exposure to lycopene. Lycopene induced apoptosis for the MDA-MB-231 cells, but not for the MCF-7 cells. CONCLUSION: Lycopene inhibits the growth of ER-positive MCF-7 cells through the inhibition of the cell cycle progression. The inhibition of ER- negative MDA-MB-231 cells by lycopene is associated not only with the G1 phase cell cycle-arrest but also the induction of apoptosis.