N-3 polyunsaturated fatty acids accentuate B16 melanoma growth and metastasis through suppression of tumoricidal function of T cells and macrophages.

BACKGROUND

The antitumor effects of the n-3 polyunsaturated fatty acids (PUFAs) are still controversial and as yet undefined.

MATERIALS AND METHODS

EPA-28, a fish oil enriched with n-3 PUFAs including eicosapentaenoic and docosahexaenoic acids, was administered subcutaneously into C57BL/6 mice before and after subcutaneous inoculation of B16 melanoma cells. The effects of EPA-28 on the antitumor activities of T cells and macrophages were investigated.

RESULTS

The treatment of the mice with EPA-28 before and after the tumor inoculation enhanced the growth and metastasis of B16 melanoma and decreased the survival rate of the tumor-bearing mice. The treatment also decreased the number of CD4+ T cells in the spleen and tumor draining lymph nodes on day 14 after the tumor inoculation. Moreover, EPA-28 suppressed the antimelanoma cytolytic activity of T cells and macrophages of the tumor-bearing mice.

CONCLUSION

The results suggest that EPA-28 treatment increased both the growth and metastasis of B16 melanoma cells by suppressing the cytolytic function of both T cells and macrophages.