Repression of mammosphere formation of human breast cancer cells by soy isoflavone genistein and blueberry polyphenolic acids suggests diet-mediated targeting of cancer stem-like/progenitor cells

Abstract

Mammary stem cells are undifferentiated epithelial cells, which initiate mammary tumors and render them resistant to anticancer therapies, when deregulated. Diets rich in fruits and vegetables are implicated in breast cancer risk reduction, yet underlying mechanisms are poorly understood. Here, we addressed whether dietary factors selectively target mammary epithelial cells that display stem-like/progenitor subpopulations with previously recognized tumor-initiating potential. Using estrogen receptor-positive MCF-7 and estrogen receptor-negative MDA-MB-231 human breast cancer cell lines and freshly isolated epithelial cells from MMTV-Wnt-1 transgenic mouse mammary tumors, we demonstrate that sera of adult mice consuming soy isoflavone genistein (GEN) or blueberry (BB) polyphenol-containing diets alter the population of stem-like/progenitor cells, as measured by their functional ability to self-renew and form anchorage-independent spheroid cultures in vitro at low frequency (1-2%). Serum effects on mammosphere formation were dose-dependently replicated by GEN (40 nM >2 μM) and targeted the basal stem-like CD44+/CD24-/ESA+ and the luminal progenitor CD24+ subpopulations in MDA-MB-231 and MCF-7 cells. GEN inhibition of mammosphere formation was mimicked by the Akt inhibitor perifosine and was associated with enhanced tumor suppressor phosphatase and tensin homologue deleted on chromosome ten (PTEN) expression. In contrast, a selected mixture of BB phenolic acids was only active in MDA-MD-231 cells and its CD44+/CD24-/ESA+ subpopulation, and this activity was independent of induction of PTEN expression. These findings delineate a novel and selective function of distinct dietary factors in targeting stem/progenitor cell populations in estrogen receptor-dependent and -independent breast cancers.

Metformin and soybean-derived bioactive molecules attenuate the expansion of stem cell-like epithelial subpopulation and confer apoptotic sensitivity in human colon cancer cells

“…Moreover, in a mouse model of breast cancer and in breast cancer cells in vitro, dietary intake of soy protein isolate and treatment with Gen, respectively, decreased the frequency of the mammary basal stem celllike subpopulation, which was associated with decreased mammary tumor incidence and oncogenic molecular profile (Montales et al 2012;Rahal et al 2013). Based on this previous body of work, we hypothesized that combination(s) of MET and bioactive soy factors would increase the therapeutic efficacy of the CRC drug 5-FU by targeting cancer stem cells.…”

“…CD44 ? cell fractions were seeded at a density of 2 9 10 3 cells per well in ultra-low attachment plates (Corning Inc., Corning, NY) in plating medium [phenol red-free MEM supplemented with B27 media (Invitrogen); 20 ng/ml human basic fibroblast growth factor (Invitrogen, Carlsbad, CA), 20 ng/ml epidermal growth factor (Invitrogen), 10 lg/ml heparin (Sigma-Aldrich), 1 % ABAM, and 100 lg/ml gentamicin (Sigma-Aldrich)] (Montales et al 2012). Treatments were MET (60 lM), soy bioactive factors (3 lM each for b-con and Gly; 2 lM each for Lun and Gen), and insulin (2 lM), singly and with the indicated combinations.…”

“…(F) (Montales et al 2012). Primers (Supplemental Table 1) were designed using Primer Express (Applied Biosystems, Foster City, CA) and synthesized by Integrated DNA Technologies, Inc. (Coralville, IA).…”

“…Nevertheless, the potential interactions of MET and bioactive dietary components with known antitumor activities for CRC prevention and treatment, and specifically in the context of targeting CSC, have not been delineated. The importance of the latter is underscored by recent reports that dietary factors including the soy isoflavone genistein (Gen) (Montales et al 2012;Rahal et al 2013), polyphenolic compounds present in blueberries (Montales et al 2012), curcumin (Kakarala et al 2010), and resveratrol (Kao et al 2009), all of which have been reported to possess anti-metabolic/anti-diabetic properties (Gilbert and Liu 2013;Valsecchi 2013;Yeh et al 2014;Rouse et al 2014), can inhibit expansion of basal stem-like mammary cells with tumorigenic potential.…”

Endocrine Disruptors and Breast Cancer Risk - Time to Consider the Environment

“…In vitro studies of the effect of soy isoflavones on breast cancer cell lines reported some beneficial effects such as reactivation of tumor suppressor genes BRCA1 and BRCA2 silenced by promoter hypermethylation (Bosviel et al, 2012), inhibition of the breast cancer progenitor cell proliferation (Montales et al, 2012), induction of apoptosis and inhibiting the proliferative signals mediated through NFκB (Seo et al, 2011). Conversely, some others have noticed opposite, stimulatory, effects on tumor cell growth (van Duursen et al, 2011).…”