Effects of tuna oil on tumor growth and metastasis to liver in intrasplenic Lewis lung carcinoma (LLC)-implanted mice

Abstract

There are a number of reports that n-3 polyunsaturated fatty acids (PUFA) in fish oils have various physiological effects such as anti-hyperlipidemic, anti-thrombosis and anti-tumor actions. UFA such as oleic acid, linoleic acid, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in tuna oil are composed in triacylglycerols (TAG). In the present study, we examined the antitumor and antimetastatic activities of tuna triacylglycerols. Tuna triacylglycerols (1000 mg/kg) significantly inhibited the tumor growth in the spleen of mice with intrasplenically implanted Lewis lung carcinoma (LLC). In the LLC-bearing mice, the liver metastasis was inhibited by orally administered tuna triacylglycerols (1000 or 2000 mg/kg). DHA mainly contains as the fatty acids in the tuna triacylglycerols. We found that free DHA inhibited the DNA synthesis in LLC cells and human microvascular endothelial cells (HMVEC), and Matrigel-induced capillary-like tube formation by HMVEC in vitro. In conclusion, it seems likely that the antitumor and antimetastatic activities of tuna triacylglycerols may partly be associated with the inhibition of the DNA synthesis in tumor and endothelial cells, and tumor-induced angiogenesis by free DHA produced from tuna oils.