DIETARY-EFFECTS OF FATTY-ACIDS ON GROWTH AND METASTASIS OF KPL-1 HUMAN BREAST-CANCER CELLS IN-VIVO AND IN-VITRO

To evaluate the effects of dietary fats on breast cancer growth and me tastasis, KPL-1 human breast carcinoma cells which have a propensity f or axillary lymph node metastasis when inoculated into the thoracic ma mmary fat pad of female nude mice were examined. The mice were fed one of three semipurified diets containing 9.5% eicosapentaenoic acid plu s 0.5% linoleic acid (EPA diet), 10% linoleic acid (LA diet), or 9.5% palmitic acid plus 0.5% linoleic acid (PA diet), or commercial laborat ory chow containing 8. 5% fat of which 4.1% was LA, 1.1% was PA, 0.06% was EPA, and 3.24% was other (Standard diet) starting 19 days before tumor cell inoculation and continuing until the end of the experiment (43 days after tumor cell inoculation). The tumor growth was faster an d at a higher incidence in the mice fed the LA diet, and much slower a nd at a lower incidence in the EPA diet group compared with the mice f ed the PA or Standard diet; the two separate experiment demonstrated i dentical results. The differences in tumor weight between the LA and P A groups and between the PA and EPA groups were significant (P < 0.05, respectively) at the termination of the experiment; the differences w ere due to different tumor cell proliferation rates. In an in vitro MT T assay, fatty acids showed direct stimulatory ol inhibitory effects o n the KPL-1 cells. Lymph node metastasis was seen in the LA and Standa rd diet groups, whereas it was not seen in the PA or EPA groups. The b ody weights were significantly lighter in the LA and EPA groups compar ed with the PA and Standard diet groups (P < 005 respectively). The re sults indicate that the EPA diet produced a. reduction in tumor cell g rowth and metastasis whereas the LA diet had an enhancing effect on th ese parameters; dietary fatty acids may thus have a direct role in the growth and metastasis of human breast carcinoma independent of their systemic effects.