Fucoxanthin, a natural carotenoid, induces G1 arrest and GADD45 gene expression in human cancer cells.

BACKGROUND Although the antitumor effects of fucoxanthin are known, the precise mechanism of action has yet to be elucidated. MATERIALS AND METHODS HepG2 and DU145 cells were used for these investigations. The effect of fucoxanthin on gene expression was assayed using a DNA microarray system. Northern blot and/or quantitative RT-PCR were carried out to confirm any changes in gene expression. The effect of fucoxanthin on cell cycle progression was analyzed using flow cytometry. RNA interference experiments were employed for the GADD45 gene. RESULTS Fucoxanthin markedly induced GADD45A, a cell cycle-related gene, in HepG2 and DU145 cells. Concomitant G1 arrest, but not apoptosis, was observed in both cell types following treatment with fucoxanthin. The introduction of siRNA against GADD45A partially perturbed the induction of Gi arrest by fucoxanthin in both cell types. CONCLUSION Fucoxanthin induced G1 arrest in HepG2 and DU145 cells. GADD45A may be involved in fucoxanthin-induced G1 arrest.