EFFECTS OF DIETARY MENHADEN OIL, SOY, AND A CYCLOOXYGENASE INHIBITOR ON HUMAN BREAST-CANCER CELL-GROWTH AND METASTASIS IN NUDE-MICE

The purpose of Study 1 was to examine the effect of dietary soy on the progression of MDA-MB-435 human breast cancer cell solid tumors in nu de mice. When toasted soy chips were fed at levels of 5%, 10%, or 20% (wt/wt) in a high-fat, linoleic acid-rich diet for 12 weeks, there was a trend for larger mammary fat pad tumors to occur with increasing so y intake. However, compared with the controls the severity of macrosco pic lung metastasis was reduced significantly in the groups fed 10% an d 20% soy. Study 2 compared the effects of diets containing 23% corn o il (CO), 18% menhaden oil (MO) + 5% CO, 18% MO + 5% CO + 10% soy chips , and MO or soy-supplemented diets + indomethacin treatment in the sam e animal model. Feeding the 18% MO diet without soy or indomethacin re duced primary tumor growth; statistically significant effects were not observed in any of the other groups. All three of the groups with MO supplementation showed a reduction in the occurrence and severity of m acroscopic lung metastases, together with the expected decreases in tu mor prostaglandin E levels. These effects were most pronounced when MO was combined with indomethacin treatment. When indomethacin was given with dietary soy, the previously reported suppressive effect of the c yclooxygenase inhibitor on MDA-MB-435 cell tumor progression was lost, despite reductions in tumor prostaglandin E concentrations.