CINNAMIC ACID INHIBITS PROLIFERATION AND MODULATES BRUSH-BORDER MEMBRANE ENZYME-ACTIVITIES IN CACO-2 CELLS

The objective of the present study was to examine whether cinnamic aci d exerts antitumor activity against colon cancer cells in vitro. For t his purpose we investigated the effect of cinnamic acid on cell prolif eration and on the differentiation markers alkaline phosphatase, sucra se and aminopeptidase N in human colon adenocarcinoma cells (Caco-2). Cinnamic acid (2.5-8.0 mM) prolonged the doubling time and inhibited t he DNA synthesis of growing cells. The antiproliferative effect occurr ed rapidly after 2 h of treatment with 8.0 mM cinnamic acid and reache d nearly maximal values after 8 h of treatment. Sucrase and aminopepti dase N activities were stimulated under cinnamic acid treatment (4.0-8 .0 mM), while alkaline phosphatase activity was inhibited in postconfl uent cells (8.0 mM). Similar effects on enzyme activities were seen in non-proliferating cells. Cinnamic acid did not alter the adhesion to collagen matrix or cell viability. Intracellular cAMP levels were decr eased significantly after 1 h of treatment with 8.0 mM cinnamic acid, suggesting that cinnamic acid induces its effects on enzyme activities partly by modulating the cAMP signaling pathway. (C) 1998 Elsevier Sc ience Ireland Ltd. All rights reserved.