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Supplement: International Conference on Diet, Nutrition, and Cancer

Green Tea Polyphenol Epigallocatechin-3 Gallate (EGCG) Affects Gene Expression of Breast Cancer Cells Transformed by the Carcinogen 7,12-Dimethylbenz[a]Anthracene^1,2,3

Department of Biochemistry and Women’s Health Interdisciplinary Research Center, Boston University School of Medicine, Boston, MA 02118-2394; and ^* Cancer Metastasis Research Center, Yonsei University College of Medicine, Seodaemun-Gu, Seoul 120–752, Korea

⁴To whom correspondence should be addressed. E-mail: gsonensh{at}bu.edu.

ABSTRACT

Since the 1980s, the incidence of late-onset breast cancer has been increasing in the United States. Known risk factors, such as genetic modifications, have been estimated to account for 5 to 10% of breast cancer cases, and these tend to be early onset. Thus, exposure to and bioaccumulation of ubiquitous environmental chemicals, such as polycyclic aromatic hydrocarbons (PAHs), have been proposed to play a role in this increased incidence. Treatment of female Sprague-Dawley rats with a single dose of the PAH 7,12-dimethylbenz[a]anthracene (DMBA) induces mammary tumors in 90 to 95% of test animals. We showed previously that female rats treated with DMBA and given green tea as drinking fluid displayed significantly decreased mammary tumor burden and invasiveness and a significantly increased latency to first tumor. Here we used cDNA microarray analysis to elucidate the effects of the green tea polyphenol epigallocatechin-3 gallate (EGCG) on the gene expression profile in a DMBA-transformed breast cancer cell line. RNA was isolated, in quadruplicate, from D3–1 cells treated with 60 µg/mL EGCG for 2, 7, or 24 h and subjected to analysis. Semiquantitative RT-PCR and Northern blot analyses confirmed the changes in the expression of 12 representative genes seen in the microarray experiments. Overall, our results documented EGCG-altered expression of genes involved in nuclear and cytoplasmic transport, transformation, redox signaling, response to hypoxia, and PAHs.

KEY WORDS: • EGCG • DMBA • microarray • breast cancer