Flaxseed attenuates the tumor growth stimulating effect of soy protein in ovariectomized athymic mice with MCF‐7 human breast cancer xenografts

Abstract

In several epidemiological studies, a phytoestrogen-rich diet containing lignans and isoflavones is associated with reduced breast cancer risk, but experimental findings are controversial. In postmenopausal mammary cancer xenograft model, flaxseed (FS), a rich source of plant lignans, reduced breast cancer growth, while soy protein (SP), a rich source of isoflavones, enhanced it. The intake of phytoestrogens is increasing particularly among postmenopausal women, emphasizing the importance of elucidating their interactive effects on breast cancer. Our study determined the effect of FS and SP diets, alone and in combination, on the established human breast cancer MCF-7 tumor growth in ovariectomized athymic nude mice. Tumor bearing mice were divided into 4 groups and fed for 25 weeks either the basal diet (BD), or BD supplemented with 10% FS, 20% SP or 10% FS and 20% SP. After estrogen deprivation, FS regressed the tumor size similar to that of control. SP initially regressed the tumors but starting at week 13, the tumors regressed significantly less than in control and 43% of the tumors were regrowing until the end of the experiment and were significantly larger in size than in control. The combination of SP with FS reduced the tumor growth similar to that of control, as suggested also by the reduced tumor cell proliferation index. In conclusion, dietary FS did not stimulate the growth of estrogen responsive MCF-7 cancers in ovariectomized mice, while long-term consumption of SP did. Furthermore, FS reduced the tumor growth stimulating effect of SP to the same level as control, suggesting tumor growth attenuating effect of FS. ' 2006 Wiley-Liss, Inc.

Low Dose Estrogen Supplementation Reduces Mortality of Mice in Estrogen-Dependent Human Tumor Xenograft Model

“…Similar observations have also been reported using estrogen-dependent MCF-7 tumor xenograft models. [7][8][9] Saarinen and coworkers reported that while they evaluate the effect of soy protein and flaxseed, a rich source of plant lignans, on tumor growth in estrogen-dependent MCF-7 tumor xenograft model, mice in various treatment groups died before the end of experiment due to unknown reason.…”

“…2,4) In the process of establishing a MCF-7 tumor xenograft model, we observed the unexplained death of some mice, similar to the experiences of others. [7][8][9] The present investigation was undertaken to find an explanation for these deaths. We also examined whether supplementation with a reduced amount of estrogen might support the growth of MCF-7 cells implanted to nude mice.…”

Apical electrolyte concentration modulates barrier function and tight junction protein localization in bovine mammary epithelium

“…Many in vitro mammary epithelial cell lines are currently being used to study the dynamics of the gland and to examine a variety of pathologies, including breast cancer (11,15,26,28,37). In most cases mammary cancer cell lines of epithelial origin are being grown on solid supports, which precludes full membrane polarization and the opportunity to assess physiological function.…”

Plant Extracts and Plant-Derived Compounds: Promising Players in Countermeasure Strategy Against Radiological Exposure: A Review

“…Linum usitatissimum L. (Family: Linaceae) produces flaxseed (FS), rich in omega-3 fatty acids and lignans, and has been reported to exhibit antitumor (Wang et al, 2005;Saarinen et al, 2006;Bergman et al, 2007;Zhang et al, 2008;Chen et al, 2009;Lindahl et al, 2011), free radicalscavenging ability and prevention against oxidative tissue damages when administered prior to radiation exposure (Kinniry et al, 2006;Dupasquier et al, 2007;Lee et al, 2008;Razi et al, 2011). Antioxidant action of FS was evaluated in PMVEC, isolated from murine lungs (Lee et al, 2009).…”