The influence of lycopene on the proliferation of human breast cell line (MCF-7)

Lycopene, a non-provitaminic carotenoid, present in many fruit and vegetables, such as tomatoes and their processed products, has been associated with decreased risk of chronic diseases including cancer. The influence of lycopene on the proliferation of the breast tumour cell line (MCF-7) was tested using MTT and BrdU assays at different time intervals (from 24 to 72 h) and dose-response (from 0.125 to 100 mu M). The induction of Gap Junction Intercellular Communication (GJIC) was evaluated by dye-transfer assay using Lucifer Yellow on monolayer cells treated with different lycopene concentrations (from 0.125 to 5 mu M) for 6 to 48 h. The Minimal Inhibitory Concentration (MIC) of lycopene was of 5 mu M, after a 24 h exposure. A prolonged exposure time (72 h) induced a similar inhibitory effect. Lycopene stimulated the functionality of GJIC at concentrations of I mu M after 24 h and this effect was dose-dependent. The induction of GJIC by lycopene was confirmed by an increased expression of connexin 43. Collectively, the above data confirm the inhibitor effects of lycopene on MCF-7 cell growth and suggest that lycopene is involved in the modulation of the gap junction intercellular communication in this cell line, as observed for other cancer cell lines. (c) 2006 Elsevier Ltd. All rights reserved.