Dietary omega-3 polyunsaturated fatty acids promote colon carcinoma metastasis in rat liver
Griffini, P.; Fehres, O.; Klieverik, L.; Vogels, I.M.; Tigchelaar, W.; Smorenburg, S.M.; Van Noorden, C.J.
Cancer Research 58(15): 3312-3319
1998
ISSN/ISBN: 0008-5472 PMID: 9699661 Document Number: 486831
The effects of OMEGA-3 polyunsaturated fatty acids (PUFAs) and OMEGA-6 PUFAs on the development of experimentally induced colon carcinoma metastasis in rat liver were investigated quantitatively in vivo. Rats were kept on either a low-fat diet or on a fish oil (OMEGA-3 PUFAs) or safflower oil (OMEGA-6 PUFAs) diet for 3 weeks before the administration of colon cancer cells to the portal vein, until they were sacrificed at 1 or 3 weeks after tumor transplantation. At 1 week after transplantation, the fish oil diet had induced 7-fold more metastases (in terms of number and size) than had the low-fat diet, whereas the safflower oil diet had not affected the number and total volume of metastases. At 3 weeks after tumor transplantation, the fish oil diet and the safflower oil diet had induced, respectively, 10- and 4-fold more metastases (number) and over 1000- and 500-fold more metastases (size) than were found in the livers of rats on the low-fat diet. These differences were sex independent. Immunohistochemical analysis revealed that the immune system in the liver (Kupffer cells, pit cells, T cells, newly recruited macrophages, and the activation state of macrophages) did not play a significant role in this diet-dependent outgrowth of tumors. In conclusion, OMEGA-3 and OMEGA-6 PUFAs promote colon cancer metastasis in the liver without down-regulating the immune system. This finding has serious implications for the treatment of cancer patients with fish oil diet to right cachexia.