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Effect of Epigallocatechin gallate (EGCG), a green tea ployphenol, on estrogen regulated genes in breast cancer cell line MCF7.

ABSTRACT: Epigallocatechin gallate (EGCG), the major green tea polyphenol, has been a subject of global interest as a potential chemopreventive or chemotherapeutic supplement for breast cancer. While on one hand epidemiological studies suggest inverse correlation between green tea consumption and breast cancer risk, investigations using cell culture and animal models of breast carcinogenesis on the other hand have demonstrated antiproliferative, antitumor, anti-invasive and anti-metastatic properties of EGCG. Mechanism of how EGCG affects cell proliferation, apoptosis, migration and cell cycle by affecting the function of a wide range of molecular targets have also been studied. However, the question as to how EGCG impacts on estrogen responsive genes has not been addressed. This issue is of relevance to our notion of EGCG as a potential chemopreventive or chemotherapeutic agent against breast cancer, which is estrogen dependent in majority of the newly diagnosed cases. Here, using the estrogen receptor α (ERα) positive MCF-7 breast cancer cells as a model, we have examined the effect of EGCG on the estrogen regulated genes.

ORGANISM(S): Homo sapiens

PROVIDER: GSE56245 | GEO | 2015/04/01

SECONDARY ACCESSION(S): PRJNA242734

REPOSITORIES: GEO

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Project description:Overexpression of the epidermal growth factor receptor family member Her-2/neu in breast cancer leads to autophosphorylation of the receptor, and induction of multiple downstream signaling pathways including Akt kinase to NF-ï«B cascade that is associated with poor prognosis. Previously, we demonstrated green tea polyhenol epigallocatechin 3-gallate (EGCG) inhibits growth of NF639 Her-2/neu-driven breast cancer cells via reducing receptor autophosphorylation, and downstream Akt and NF-ï«B activities (Pianetti et al., 2002). Interestingly, we noted that upon prolonged culture in the presence of EGCG some cells developed resistance to the polyphenol. Here we report that resistant cells have lost tyrosine phosphorylation on the Her-2/neu receptor. Surprisingly, they displayed elevated NF-ï«B activity, and inhibition of this activity sensitized cells to EGCG. Data from microarray analysis of the original and resistant NF639 populations of cells were subjected to Gene Set Enrichment Analysis (GSEA) pathway analysis, which revealed that the mitogen activated protein kinase (MAPK) pathway was activated in the resistant cells. Treatment of the resistant cells with a combination of EGCG and the MAPK inhibitor U0216 dramatically reduced colony growth and mesenchymal phenotype. Thus, activation of the MAPK pathway mediates resistance to EGCG. Our studies suggest that gene expression profiling of drug resistant cells may provide a mechanism of determining effective systemic therapies for treatment of these advanced cancers. Experiment Overall Design: Total RNA from original NF639 cells and EGCG resistant NF639 cells were harvested using the UltraspecII RNA isolation kit (Biotecx), following the manufacturerâs instruction. The RNA samples were submitted to Boston University Microarray Resource for microarray hybridization using Affymetrix Mouse 430A 2.0 chips. RNAs from two independent experiments were analyzed and data pooled for computational analysis.

Dataset Information

Effect of Epigallocatechin gallate (EGCG), a green tea ployphenol, on estrogen regulated genes in breast cancer cell line MCF7.

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