Estrogen acts as a complete mammary carcinogen in ACI rats. Prevention studies in this model allowed us to identify agents that are effective against estrogen-induced mammary carcinogenesis. In this study, we investigated efficacy of dietary berries and ellagic acid to reduce estrogen-mediated mammary tumorigenesis. Female ACI rats (8-9 wk) were fed either AIN-93M diet (n = 25) or diet supplemented with either powdered blueberry (n = 19) and black raspberry (n = 19) at 2.5% wt/wt each or ellagic acid (n = 22) at 400 ppm. Animals received implants of 17beta-estradiol 2 wk later, were palpated periodically for mammary tumors, and were euthanized after 24 wk. No differences were found in tumor incidence at 24 wk; however, tumor volume and multiplicity were reduced significantly after intervention. Compared with the control group (average tumor volume = 685 +/- 240 mm3 and tumor multiplicity = 8.0 +/- 1.3), ellagic acid reduced the tumor volume by 75% (P < 0.005) and tumor multiplicity by 44% (P < 0.05). Black raspberry followed closely, with tumor volume diminished by > 69% (P < 0.005) and tumor multiplicity by 37% (P = 0.07). Blueberry showed a reduction (40%) only in tumor volume. This is the first report showing the significant efficacy of both ellagic acid and berries in the prevention of solely estrogen-induced mammary tumors.

To determine whether dietary berries and ellagic acid prevent 17β-estradiol (E 2 )-induced mammary tumors by altering estrogen metabolism, we randomized August-Copenhagen Irish rats (n = 6 per group) into five groups: sham implant + control diet, E 2 implant + control diet (E 2 -CD), E 2 + 2.5% black raspberry (E 2 -BRB), E 2 + 2.5% blueberry (E 2 -BB), and E 2 + 400 ppm ellagic acid (E 2 -EA). Animals were euthanized at early (6 wk), intermediate (18 wk), and late (24 wk) phases of E 2 carcinogenesis, and the mammary tissue was analyzed for gene expression changes using quantitative real-time PCR. At 6 weeks, E 2 treatment caused a 48-fold increase in cytochrome P450 1A1 (CYP1A1; P < 0.0001), which was attenuated by both BRB and BB diets to 12-and 21-fold, respectively (P < 0.001). E 2 did not alter CYP1B1 levels, but both berry and EA diets significantly suppressed it by 11-and 3.5-fold, respectively, from baseline (P < 0.05). There was a 5-fold increase in 17β-hydroxysteroid dehydrogenase 7 (17βHSD7), and this was moderately abrogated to ∼2-fold by all supplementation (P < 0.05). At 18 weeks, CYP1A1 was elevated by 15-fold in E 2 -CD and only E 2 -BB reduced this increase to 7-fold (P < 0.05). Catechol-O-methyltransferase expression was elevated 2-fold by E 2 treatment (P < 0.05), and all supplementation reversed this. At 24 weeks, CYP1A1 expression was less pronounced but still high (8-fold) in E 2 -treated rats. This increase was reduced to 3.2-and 4.6-fold by E 2 -BRB and E 2 -EA, respectively (P < 0.05), but not by E 2 -BB. Supplementation did not alter the effect of E 2 on steroid receptors. The diets also significantly suppressed mammary tumor incidence (10-30%), volume (41-67%), and multiplicity (38-51%; P < 0.05). Berries may prevent mammary tumors by suppressing the levels of E 2 -metabolizing enzymes during the early phase of E 2 carcinogenesis. Cancer Prev Res; 3(6); 727-37. ©2010 AACR.

Breast cancer is the most commonly diagnosed cancer among women worldwide. Many women have become more aware of the benefits of increasing fruit consumption, as part of a healthy lifestyle, for the prevention of cancer. The mechanisms by which fruits, including berries, prevent breast cancer can be partially explained by exploring their interactions with pathways known influence cell-proliferation and evasion of cell-death. Two receptor pathways- estrogen receptor (ER) and tyrosine kinase receptors, especially the epidermal growth factor receptor (EGFR) family- are drivers of cell-proliferation and play a significant role in the development of both primary and recurrent breast cancer. There is strong evidence to show that several phytochemicals present in berries such as cyanidin, delphinidin, quercetin, kaempferol, ellagic acid, resveratrol and pterostilbene, interact with and alter the effects of these pathways. Further, they also induce cell death (apoptosis and autophagy) via their influence on kinase signaling. In this review, we summarize in vitro data regarding the interaction of berry polyphenols with the specific receptors and the mechanisms by which they induce cell death. Further, we also present in vivo data of primary breast cancer prevention by individual compounds and whole berries. Finally, we present a possible role for berries and berry compounds in the prevention of breast cancer and our perspective on the areas that require further research.

Lack of understanding of endocrine resistance remains one of the major challenges for breast cancer researchers, clinicians, and patients. Current reductionist approaches to understanding the molecular signaling driving resistance have offered mostly incremental progress over the past 10 years. As the field of systems biology has begun to mature, the approaches and network modeling tools being developed and applied therein offer a different way to think about how molecular signaling and the regulation of critical cellular functions are integrated. To gain novel insights, we first describe some of the key challenges facing network modeling of endocrine resistance, many of which arise from the properties of the data spaces being studied. We then use activation of the unfolded protein response (UPR) following induction of endoplasmic reticulum stress in breast cancer cells by antiestrogens, to illustrate our approaches to computational modeling. Activation of UPR is a key determinant of cell fate decision making and regulation of autophagy and apoptosis. These initial studies provide insight into a small subnetwork topology obtained using differential dependency network analysis and focused on the UPR gene XBP1. The XBP1 subnetwork topology incorporates BCAR3, BCL2, BIK, NFκB, and other genes as nodes; the connecting edges represent the dependency structures amongst these nodes. As data from ongoing cellular and molecular studies become available, we will build detailed mathematical models of this XBP1-UPR network.

DNA damage is a pre-requisite for the initiation of cancer and agents that reduce this damage are useful in cancer prevention. In this study, we evaluated the ability of whole berries and berry phytochemical, ellagic acid to reduce endogenous oxidative DNA damage. Ellagic acid was selected based on >95% inhibition of 8-oxodeoxyguosine (8-oxodG) and other unidentified oxidative DNA adducts induced by 4-hydroxy-17ß-estradiol and CuCl 2 in vitro. Inhibition of the latter occurred at lower concentrations (10 µM) than that for 8-oxodG (100 µM). In the in vivo study, female CD-1 mice (n=6) were fed either a control diet or diet supplemented with ellagic acid (400 ppm) and dehydrated berries (5% w/w) with varying ellagic acid contents -blueberry (low), strawberry (medium) and red raspberry (high), for 3 weeks. Blueberry and strawberry diets showed moderate reductions in endogenous DNA adducts (25%). However, both red raspberry and ellagic acid diets showed a significant reduction of 59% (p <0.001) and 48% (p < 0.01), respectively. Both diets also resulted in a 3-8 fold over-expression of genes involved in DNA repair such as xeroderma pigmentosum group A complementing protein (XPA), DNA excision repair protein (ERCC5) and DNA ligase III (DNL3). These results suggest that red raspberry and Int. J. Mol. Sci. 2008, 9 328 ellagic acid reduce endogenous oxidative DNA damage by mechanisms which may involve increase in DNA repair.