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Research Grants Awarded
Natural Indole Control of the Promotion of Precancerous Breast Cells
Clinical breast cancer is thought to arise from promotion of malignant precancerous breast lesions. Precancerous lesions, in turn, arise from weakly malignant preneoplastic breast cells. Currently, model cell systems to study promotion of precancerous lesions to clinical breast cancer do not exist. Overexpression of either estrogen receptor alpha (ER- a ) or Her2/Neu is frequently observed in precancerous lesions, and is hypothesized to influence the estrogen sensitivity of the resulting tumors. We propose to directly test whether ectopic expression of either ER- a or Her2/Neu markedly increases malignancy of human preneoplastic breast cells by assessing their ability to become precancerous cell lines that closely resemble high risk breast lesions. This model system will then be used to test the efficacy of two phytochemicals derived from cruciferous vegetables, Indole-3-Carbinol (I3C), and its dimer 3,3’-Diindolyl methane (DIM), in preventing promotion of precancerous lesions to breast cancer. Both natural indole molecules have been shown to be effective anti-proliferative agents in human breast cancer cells, however, nothing is known about the ability of I3C or DIM to inhibit promotion of precancerous breast cells to breast cancer. The overall objective of this study is to establish a novel human mammary cell system that represents precancerous lesions, and to use this model system to uncover the chemopreventative potential of I3C and DIM. The first of aim of will be to express exogenous ER- a or Her-2/Neu in MCF10AT cells, a human mammary preneoplastic cell line, in order to generate precancerous breast cell lines. The malignant phenotype and estrogen sensitivity of these precancerous cell lines will first be characterized in culture. Malignant lesion pathology, angiogenesis and tumorigenicity will be assessed by nude mouse xenografts. The second aim of this study will be to test the effects of I3C or DIM on the proliferation, cell control, and malignant phenotype in cell culture as well as in nude mouse outgrowths. This project, upon successful completion, is expected to generate two novel precancerous cell lines that closely resemble precancerous high risk lesions in the human breast, thus providing a much needed system for future studies on breast cancer prevention.
Development of clinical breast cancer from normal mammary cells occurs in a stepwise fashion. One such step in this process is the formation of altered cells with properties that resemble cancer cells (termed precancerous lesions) from their immediate predecessor cells (termed preneoplastic lesions). Inhibiting the formation and growth of these precancerous lesions would lead to a decreased incidence of clinical breast cancer. Thus, potentially promising strategies to prevent breast cancer involve the identification of therapeutic compounds that block the formation of clinical breast cancer from precancerous lesions. However, only limited experimental human mammary cell systems exist to study the progression of precancerous lesions to clinical breast cancer. I propose to develop a novel cell line system that models human precancerous lesions to characterize the chemopreventative properties of natural phytochemicals. Specifically, I plan to test the effects of Indole-3-Carbinol (I3C) and its dimer 3,3'-Diindolyl methane (DIM), which are derived from cruciferous vegetables such as broccoli, Brussels sprouts, and cabbage. Both I3C and DIM have been shown to inhibit the growth of human breast cancer cells in culture, but their effects on precancerous cells have not been studied. Starting with MCF10AT cells, a cell line that resembles human mammary preneoplastic cells, I plan to generate experimentally altered cell lines that resemble high risk precancerous lesions by elevating the levels of estrogen receptor-alpha or Her-2/neu. The rationale for this strategy is that high levels of either gene are commonly observed in high risk precancerous mammary lesions in humans and are thought to promote human breast cancer. The first aim of this proposal will be to characterize the cancerous properties of these newly developed cell lines in cell culture as well as in nude mice, which allows the formation of human mammary cell derived tumors. The second aim of this proposal will be to determine the ability of either I3C or DIM to inhibit the growth and cancer cell properties of the precancerous model cell lines in comparison to their predecessor MCF10AT cell line. The project, upon successful completion, will establish a unique cell line system to study the precancerous steps that lead to clinical breast cancer and provide a model to test novel prevention strategies, such as dietary phytochemicals.