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

Abnormal activation of the Wnt/β-catenin pathway and subsequent up-regulation of β-catenin response transcription (CRT) are associated with the development of colon cancer. Thus, the Wnt/β-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/β-catenin pathway without altering the level of β-catenin protein and reduces the expression of cyclin D1, which is a known β-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-κB (NF-κB) in SW480 colon cancer cells. Our findings suggest that EPJ attenuates Wnt/β-catenin signaling via activation of NF-κB and can potentially be used as a chemopreventive agent against colon cancer.