Polysiphonia japonica extract suppresses the Wn/β-catenin pathway in colon cancer cells by activation of NF-κB

Abnormal activation of the Wnt/beta-catenin pathway and subsequent up-regulation of beta-catenin response transcription (CRT) are associated with the development of colon cancer. Thus, the Wnt/beta-catenin pathway is an attractive target for chemoprevention and treatment of this cancer. We used a cell-based screen to identify a methanol extract of Polysiphonia japonica (EPJ) that suppresses the Wnt/beta-catenin pathway without altering the level of B-catenin protein and reduces the expression of cyclin D1, which is a known beta-catenin/T cell factor (TCF)-dependent gene. EPJ inhibited the growth of various colon cancer cells. In addition, EPJ induced the nuclear translocation of nuclear factor-kappa B (NF-kappa B) in SW480 colon cancer cells. Our findings suggest that EPJ attenuates Wnt/kappa-catenin signaling via activation of NF-kappa B and can potentially be used as a chemopreventive agent against colon cancer.