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Phytoestrogens regulate mRNA and protein levels of guanine nucleotide‐binding protein, beta‐1 subunit (GNB1) in MCF‐7 cells
Author(s) -
Naragoni Srivatcha,
Sankella Shireesha,
Harris Kinesha,
Gray Wesley G.
Publication year - 2009
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.21699
Subject(s) - estrogen receptor , estrogen receptor alpha , estrogen , messenger rna , estrogen receptor beta , biology , gene expression , microbiology and biotechnology , chemistry , gene , endocrinology , biochemistry , genetics , cancer , breast cancer
Phytoestrogens (PEs) are non‐steroidal ligands, which regulate the expression of number of estrogen receptor‐dependent genes responsible for a variety of biological processes. Deciphering the molecular mechanism of action of these compounds is of great importance because it would increase our understanding of the role(s) these bioactive chemicals play in prevention and treatment of estrogen‐based diseases. In this study, we applied suppression subtractive hybridization (SSH) to identify genes that are regulated by PEs through either the classic nuclear‐based estrogen receptor or membrane‐based estrogen receptor pathways. SSH, using mRNA from genistein (GE) treated MCF‐7 cells as testers, resulted in a significant increase in GNB1 mRNA expression levels as compared with 10 nM 17β estradiol or the no treatment control. GNB1 mRNA expression was up regulated two‐ to fivefold following exposure to 100.0 nM GE. Similarly, GNB1 protein expression was up regulated 12‐ to 14‐fold. GE regulation of GNB1 was estrogen receptor‐dependent, in the presence of the anti‐estrogen ICI‐182,780, both GNB1 mRNA and protein expression were inhibited. Analysis of the GNB1 promoter using ChIP assay showed a PE‐dependent association of estrogen receptor α (ERα) and β (ERβ) to the GNB1 promoter. This association was specific for ERα since association was not observed when the cells were co‐incubated with GE and the ERα antagonist, ICI. Our data demonstrate that the levels of G‐protein, beta‐1 subunit are regulated by PEs through an estrogen receptor pathway and further suggest that PEs may control the ratio of α‐subunit to β/γ‐subunits of the G‐protein complex in cells. J. Cell. Physiol. 219: 584–594, 2009. © 2009 Wiley‐Liss, Inc.