Curcumin-induced differential gene expression in MCF-7 breast cancer cell line
Research Institute, Miami Children's Hospital, Miami, FL, United States
Curcumin (diferuloyl methane), the yellow-colored dietary pigment from the rhizomes of turmeric (Curcuma longa L) has anti-inflammatory, anti-tumor, anti-proliferative and anti-oxidant properties. It is a potent inhibitor of mutagenesis and chemically induced carcinogenesis in animal tumor models. Curcumin regulates an array of cellular processes such as inhibition of lipid peroxidation, nictric oxide synthetase activity, epidermal growth factor (EGF) receptor intrinsic kinase activity, NFkB activity, protein kinase activity and production of reactive oxygen species. We have investigated the cytotoxic, apoptosis and gene-regulatory effects of both turmeric and the active ingredient curcumin on MCF-7 human breast carcinoma cell line and compared with their effect on MCF-10A human mammary epithelial cells. Inhibitory concentrations indicated that MCF-7 cells were more sensitive to turmeric and curcumin than MCF-10A cells. Spectrometric measurement of curcumin in the medium showed that MCF-10A cells detoxify curcumin and retain comparatively less drug in the medium than MCF-7 cells, thereby reducing cytotoxic effect in MCF-10A cells. Curcumin induced significantly higher percentage of annexin-v positive apoptotic cells in MCF-7 than MCF-10A cells. Apoptosis was usually preceded by the induction of high caspase activity. Microarray hybridization of apoptotic arrays with labeled first strand probe of total RNAs was performed to identify and characterize the genes regulated by curumin in tumor cells. Apoptotic arrays hybridized with RNA from curcumin treated cells showed upregulation of pro-apoptotic genes (caspase 2, 4, and 6, growth arrest and DNA damage inducible protein, IL-1 beta convertase, APO 1, mdm2, glutathione S-transferase mu, MAPKK1) and down-regulation of anti-apoptotic genes (p53, p73, bcl-2, c-myc, c-jun, glutathione reductase, IGF-1R, inhibitor of apoptotic protein 3-API3, defender against cell death-DAD). Of the 285 genes present in the Clonetech apoptotic array, 208 were altered by curcumin. The gene expression changes were significantly higher (upto 14-fold) in MCF-7 cells than in MCF-10A cells (<2-fold). Our results suggest that curcumin caused apoptosis in breast cancer cells by regulating a number of genes associated with apoptosis. Curcumin has enormous potential for prevention and treatment of cancer. (Supported by Miami Children's Hospital Funds for Alternative Medicine)
Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Nice, France; February 7 - 10, 2004; in oral session 793 (Dietary influences).