Suppressive effects of lycopene and β-carotene on the viability of the human esophageal squamous carcinoma cell line EC109

The molecular mechanisms underlying the chemopreventive effects of carotenoids in different types of cancer are receiving increasing attention. In the present study, the role of peroxisome proliferatoractivated receptor γ (PPARγ) in the effect of lycopene and βcarotene on the viability of EC109 human esophageal squamous carcinoma cells was investigated. The viability of EC109 cells was evaluated using MTT assays. The effects of lycopene and βcarotene on the expression of PPARγ, p21WAF1/CIP1, cyclin D1 and cyclooxygenase2 (COX2) were analyzed by western blotting. Lycopene and βcarotene (540 µM) dose and timedependently reduced the viability of the EC109 cells. GW9662, an irreversible PPARγ antagonist, partly attenuated the decrease in EC109 cell viability induced by these carotenoids. Lycopene and βcarotene treatments upregulated the expression of PPARγ and p21WAF1/CIP1, and downregulated the expression of cyclin D1 and COX2. These modulatory effects of the carotenoid treatments were suppressed by GW9662, suggesting that the inhibition of EC109 cell viability by lycopene and βcarotene involves PPARγ signaling pathways and the modulation of p21WAF1/CIP1, cyclin D1 and COX2 expression.