The polyacetylene
falcarinol, isolated from carrots, has been shown to be protective against chemically induced
colon cancer development in rats, but the mechanisms are not fully understood. In this study CaCo-2 cells were exposed to
falcarinol (0.5-100 microM) and the effects on proliferation, DNA damage, and apoptosis investigated. Low-dose
falcarinol exposure (0.5-10 microM) decreased expression of the apoptosis
indicator caspase-3 concomitantly with decreased basal
DNA strand breakage. Cell proliferation was increased (1-10 microM), whereas cellular attachment was unaffected by <10 microM
falcarinol. At concentrations above 20 microM
falcarinol, proliferation of CaCo-2 cells decreased and the number of cells expressing active
caspase-3 increased simultaneously with increased cell detachment. Furthermore,
DNA single-strand breakage was significantly increased at concentrations above 10 microM
falcarinol. Thus, the effects of
falcarinol on CaCo-2 cells appear to be biphasic, inducing pro-proliferative and apoptotic characteristics at low and high concentrations of
falcarinol, respectively.