DESCRIPTION: Iron is an essential nutrient utilized in metabolic processes and in cell proliferation. In addition, mammary epithelial cells have a unique requirement for iron, because they synthesize iron-lactoferrin complex as an iron source of mother's milk to meet the iron needs of the newborn. Our hypothesis is that the chronic ingestion of diets containing high iron concentrations overloads the iron storage and utilization capacity of mammary cells and in concert with estrogen induces mammary tumors. The excess iron may cause toxicities such as lipid peroxidation and free radical-mediated DNA and protein damage. Cells damaged by these processes and at the same time responding to estrogen stimulation of growth may be transformed and develop into mammary tumors. Dr. Liehr will examine this hypothesis by addressing the following questions. 1. a) Does iron accumulate in kidney of hamsters or mammary tissue of Noble (Nb) rats (animal models for estrogen-induced carcinogenesis) in response to estrogen treatment? b) Is this iron accumulation an estrogen receptor-dependent process? c) Does iron continue to accumulate in these rodent organs under conditions of chronic treatment with estradiol implants and cause toxicity at excess tissue iron concentrations? d)Does iron redistribute to organs of estrogen-induced carcinogenesis in estrogen-treated animals receiving a low iron-containing diet? 2. Does a low iron diet (3.5 ppm Fe) prevent estrogen-induced carcinogenesis? 3. Does iron accumulate in "normal" tissue surrounding tumors of breast cancer patients compared to controls? 4. What are the cellular mechanisms of action and interaction between iron and estrogens in MCF-10A immortal human mammary epithelial cells and in MCF-7 breast cancer cells? His studies will determine whether dietary iron accumulation causes breast cancer. In future experiments he will extend his findings to understanding the interactions of vitamins A and D with estrogens and iron in the etiology of breast cancer, and extend his hypothesis to prostate cancer.