Effect of dietary linoleic acid level on lodgement, proliferation and survival of mammary tumor metastases.

ABSTRACT

High levels of dietary linoleic acid (182) have been shown to increase the spontaneous metastasis of line 4526 mouse mammary tumors. In this report, the influence of 182 on specific events of tumor metastasis, namely, lodgement, proliferation and survival, were studied using spontaneous and experimental metastasis assays with line 4526 cells. A significantly greater number of radiolabeled tumor cells lodged in the lungs of mice fed 4, 8 and 12% 182 when compared with mice fed lower levels of 182. The effect of dietary 182 appeared to be on the host tissue (lungs) and not the tumor cells. Lodgement of tumor cells first cultured in serum of mice fed 182 then injected into mice fed 1% 182 was not affected. There were no significant differences in the percentage of [3H]thymidine labeled metastatic cells from lungs of mice fed different levels of 182. However, the number of surface lung nodules that appeared in mice 21 days after injection of unlabeled line 4526 cells increased in mice fed 8 and 12% 182 compared with those fed lower levels of 182. Thus, dietary 182 may increase metastasis by influencing the lodgement, implantation and survival but not proliferation of line 4526 mouse mammary tumor cells.