Flaxseed oil reduces the growth of human breast tumors (MCF-7) at high levels of circulating estrogen.
Flaxseed (FS) has been shown to attenuate mammary tumorigenesis, possibly due to its high alpha-linolenic acid (ALA)-rich oil (FSO) content. This study determined the effect of FSO on the growth of estrogen receptor-positive human breast tumors (MCF-7) in ovariectomized athymic mice at high premenopausal-like estrogen (E2) levels. Mice with established MCF-7 tumors were fed basal diet (control) or basal diet supplemented with FSO (40 g/kg) for 8 wks. Compared with control, FSO reduced tumor size (33%, p<0.05) and tumor cell proliferation (38%, p<0.05) and increased apoptosis (110%, p<0.001). FSO also reduced human epidermal growth factor receptor-2 (79%, p<0.05) and epidermal growth factor receptor (57%, p=0.057) expression, which then may have led to a reduction in Akt (54%, p<0.05) and phosphorylation of mitogen-activated protein kinase (MAPK) to phosphorylated MAPK (pMAPK, 28%, p<0.05). Insulin-like growth factor-1 receptor, vascular endothelial growth factor receptor, MAPK and phosphorylated Akt were not affected. FSO increased (p<0.001) serum ALA, eicosapentaenoic acid and docosahexaenoic acid and, in vitro, ALA reduced MCF-7 cell proliferation (33%, p<0.001). Thus, FSO regressed estrogen receptor-positive human breast tumorigenesis at high E2 levels via downregulation of the growth factor mediated pathway, likely through its ALA content, and may explain the anti-tumorigenicity of FS.
Inhibitory effects of rosemary extracts, carnosic acid and rosmarinic acid on the growth of various human cancer cell lines.
The leaves of Rosmarinus officinalis harvested from three different locations of Turkey were extracted by both methanolic and supercritical CO(2) extraction. Subsequently, six extracts and the active compounds, carnosic acid, and rosmarinic acid were applied to various human cancer cell lines including NCI-H82 (human, small cell lung, carcinoma), DU-145 (human, prostate, carcinoma), Hep-3B (human, black, liver, carcinoma, hepatocellular), K-562 (human chronic myeloid leukemia), MCF-7 (human, breast, adenocarcinoma), PC-3 (human, prostate, adenocarcinoma) and MDA-MB-231 (human, breast, adenocarcinoma) by MTT assay. Supercritical CO(2) extracts had superior antiproliferative effect compared to the soxhlet extracts. Although the extracts exhibited various cytotoxic effects against different cell lines, comparatively low IC(50) values ranging between 12.50 and 47.55 microg/ml were attained against K-562, being the most sensitive cell line. Moreover, carnosic acid caused the lowest cell viability with values ranging from 13 to 30 % at a concentration of 19 muM after 48 h of treatments, resulting in superior antiproliferative effect. Rosemary extract is a potential candidate to be included in the anti-cancer diet with pre-determined doses avoiding toxicity.