Mechanism of Anti-Invasive Action of Docosahexaenoic Acid in SW480 Human Colon Cancer

Colon cancer is one of the most common malignancies in the western world and the second leading cause of cancer death in Korea. Epidemiology studies have shown a reduced incidence of colon cancer among populations consuming a large quantity of ω3-polyunsaturated fatty acids (ω3-PUFA) of ma-rine origin. Recently, it has been found that ω3-PUFA has an antineoplastic effect in several cancers. This study was designed to investigate the mechanism of the anti-invasive effect of ω3-PUFA in colon cancer. ω3-PUFA, docosahexaenoic acids (DHA) and eicosapentaenoic acid (EPA) treatment resulted in a dose-dependent inhibition of cell growth in SW480 human colon cancer cells. In contrast, arach-idonic acid (AA), a ω6-PUFA, exhibited no significant effect. This action likely involves apoptosis, giv-en that DHA treatment increased apoptotic cells in TUNEL assay. Moreover, invasiveness of SW480 cells was inhibited following treatment of DHA in a dose-dependent manner; in contrast, AA had no effect. The levels of MMP-9 and MMP-2 mRNA decreased after DHA pretreatment. MMP-9 and MMP-2 promoter activities were also inhibited by DHA treatment. The levels of NF-kB and p-IkB pro-tein were down-regulated by DHA pretreatment in a dose dependent manner. In addition, DHA in-hibited NF-kB promoter reporter activities. These findings suggest that ω3-PUFA may inhibit cancer cell invasion by inhibition of MMPs via reduction of NF-kB in colon cancer. In conclusion, ω3-PUF