Year of Publication

2007

Document Type

Dissertation

College

Graduate School

Department

Nutritional Sciences

First Advisor

Ramesh C. Gupta

Abstract

Breast cancer is the most frequently diagnosed cancer among women around the world. The hormone 17-estradiol (E2) is strongly implicated as a causative agent in this cancer. Since estrogen acts as a complete carcinogen, agents that interfere with the carcinogenic actions of E2 are required. Most agents effective against experimental mammary carcinogenesis have been employed as pure compounds disregarding the synergy that exists between several phytonutrients in a whole food. In these studies we have taken a unified approach, by employing a pure phytonutrient ellagic acid and whole foods that contain the phytonutrient at various levels berries, in the prevention of E2- induced mammary cancer in ACI rats. We have also used a tiered approach by screening several phytochemicals in vitro and implementing these results in both short- and long-term studies. Initially, several phytochemicals were tested as pure compounds against oxidative DNA damage induced by 4-hydroxy estradiol and CuCl2. Ellagic acid, was the most effective agent (andgt;98% reduction). In a short-term in vivo study, both dietary blueberry and strawberry (5% w/w), were ineffective in reducing the baseline oxidative DNA damage in the livers of CD-1 mice. However, red raspberry (5% w/w) was highly effective (50% reduction) and ellagic acid (400 ppm) was moderately effective (25% reduction). Further both diets up-regulated hepatic DNA repair genes in a similar fashion. In a long-term estradiol-induced mammary carcinogenicity study in ACI rats, dietary berries (2.5% w/w) and ellagic acid (400 ppm) reduced both tumor volume and tumors per animal to different extents (50-75%). One mechanism by which these dietary interventions inhibit mammary tumorigenesis may be via modulation of E2 metabolism, especially at the early stages of carcinogenesis. At 6 weeks after E2 treatment both berries and ellagic acid or berries alone significantly offset E2- induced changes in CYP1B1 and CYP1A1 expressions respectively. In addition, no toxicity or adverse effects are observed when rodents were fed either berries (1 - 5%) or ellagic acid (400 ppm). These data taken collectively support the possibility of using natural foods such as berries as an adjuvant to current pharmacological therapies in the prevention and treatment of breast cancer.

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