Modulatory effects of quercetin on proliferation and differentiation of the human colorectal cell line Caco-2

The effect of the dietary flavonoid quercetin was investigated on proliferation and differentiation of the human colon cancer cell line Caco-2. Confluent Caco-2 monolayers exposed to quercetin showed a biphasic effect on cell proliferation and a decrease in cell differentiation (0.001 < P < 0.05). During differentiation Caco-2 cells formed 5 phase II metabolites, of which the amount of 4'-O-methyl-quercetin-3'-O-glucuronide correlated with the differentiation grade (r = 0.99, P < 0.003). The increment of cell proliferation at low quercetin concentrations and the decrease in cell differentiation are effects opposite to what would be expected for a functional food ingredient with anti-carcinogenic potential. (c) 2005 Elsevier Ireland Ltd. All rights reserved.