Recent studies indicate that diets rich in phytoestrogens and n-3 fatty acid have anticancer potential. This study determined the effect of flaxseed (FS), the richest source of lignans and alpha-linolenic acid, on growth and metastasis of established human breast cancer in a nude mice model. Estrogen receptor-negative human breast cancer cells, MDA-MB-435, were injected into the mammary fat pad of mice (Ncr nu/nu) fed a basal diet (BD). At Week 8, mice were randomized into two diet groups, such that the groups had similar tumor size and body weight. One continued on the BD, while the other was changed to BD supplemented with 10% FS, until sacrifice at Week 15. A significant reduction (P < 0.05) in tumor growth rate and a 45% reduction (P = 0.08) in total incidence of metastasis were observed in the FS group. Lung metastasis incidence was 55.6% in the BD group and 22.2% in the FS group, while the lymph node metastasis incidence was 88.9% in the BD group and 33.3% in the FS group (P < 0.05). Mean tumor number (tumor load) of total and lymph node metastasis was significantly lower in the FS than in the BD group (P < 0.05). Metastatic lung tumor number was reduced by 82%, and a significantly lower tumor trend (P < 0.01) was observed in the FS group. Lung weight, which also reflects metastatic tumor load, in the FS group was reduced by 20% (P < 0.05) compared with the BD group. Immunohistochemical study showed that Ki-67 labeling index and expression of insulin-like growth factor I and epithelial growth factor receptor in the primary tumor were lower in the FS (P < 0.05) than in the BD group. In conclusion, flaxseed inhibited the established human breast cancer growth and metastasis in a nude mice model, and this effect is partly due to its downregulation of insulin-like growth factor I and epidermal growth factor receptor expression.
Docosahexaenoic acid (DHA) is important for brain function, however, the exact
amount required for the brain is not agreed upon. While it is believed that the
synthesis rate of DHA from α-linolenic acid (ALA) is low, how this
synthesis rate compares with the amount of DHA required to maintain brain DHA
levels is unknown. The objective of this work was to assess whether DHA
synthesis from ALA is sufficient for the brain. To test this, rats consumed a
diet low in n-3 PUFAs, or a diet containing ALA or DHA for 15 weeks. Over the 15
weeks, whole body and brain DHA accretion was measured, while at the end of the
study, whole body DHA synthesis rates, brain gene expression, and DHA uptake
rates were measured. Despite large differences in body DHA accretion, there was
no difference in brain DHA accretion between rats fed ALA and DHA. In rats fed
ALA, DHA synthesis and accretion was 100-fold higher than brain DHA accretion of
rats fed DHA. Also, ALA-fed rats synthesized approximately 3-fold more DHA than
the DHA uptake rate into the brain. This work indicates that DHA synthesis from
ALA may be sufficient to supply the brain.
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