126: Metabolic and motile reprogramming of ER positive breast cancer cells following long-term estrogen deprivation

HOXA5 is a homeobox-containing gene associated with the development of the lung, gastrointestinal tract, and vertebrae. Here, we investigate potential roles and the gene regulatory mechanism in HOXA5 in breast cancer cells. Our studies demonstrate that HOXA5 expression is elevated in breast cancer tissues and in estrogen receptor (ER)-positive breast cancer cells. HOXA5 expression is critical for breast cancer cell viability. Biochemical studies show that estradiol (E2) regulates HOXA5 gene expression in cultured breast cancer cells in vitro. HOXA5 expression is also upregulated in vivo in the mammary tissues of ovariectomized female rats. E2-induced HOXA5 expression is coordinated by ERs. Knockdown of either ERα or ERβ downregulated E2-induced HOXA5 expression. Additionally, ER co-regulators, including CBP/p300 (histone acetylases) and MLL-histone methylases (MLL2, MLL3), histone acetylation-, and H3K4 trimethylation levels are enriched at the HOXA5 promoter in present E2. In summary, our studies demonstrate that HOXA5 is overexpressed in breast cancer and is transcriptionally regulated via estradiol in breast cancer cells.

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Insulin-like Growth Factor Receptor Levels Are Regulated by Cell Density and by Long Term Estrogen Deprivation in MCF7 Human Breast Cancer Cells

Journal of Biological Chemistry ◽

10.1074/jbc.m105892200 ◽

2001 ◽

Vol 276 (43) ◽

pp. 40080-40086 ◽

Cited By ~ 48

Author(s):

Ruth L. Stephen ◽

Lesley E. Shaw ◽

Camilla Larsen ◽

David Corcoran ◽

Philippa D. Darbre

Keyword(s):

Breast Cancer ◽

Growth Factor ◽

Cancer Cells ◽

Human Breast Cancer ◽

Breast Cancer Cells ◽

Growth Factor Receptor ◽

Human Breast Cancer Cells ◽

Human Breast ◽

Estrogen Deprivation

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SGK3 Is an Estrogen-Inducible Kinase Promoting Estrogen-Mediated Survival of Breast Cancer Cells

Molecular Endocrinology ◽

10.1210/me.2010-0294 ◽

2011 ◽

Vol 25 (1) ◽

pp. 72-82 ◽

Cited By ~ 35

Author(s):

Yuanzhong Wang ◽

Dujin Zhou ◽

Sheryl Phung ◽

Selma Masri ◽

David Smith ◽

...

Keyword(s):

Breast Cancer ◽

Protein Kinase ◽

Cell Survival ◽

Cancer Cells ◽

Breast Cancer Cells ◽

Dependent Manner ◽

Binding Regions ◽

Er Positive ◽

Mcf 7 ◽

Positive Breast Cancer

Serum- and glucocorticoid-inducible kinase 3 (SGK3) is a protein kinase of the AGC family of protein kinase A, protein kinase G, and protein kinase C and functions downstream of phosphatidylinositol 3-kinase (PI3K). Recent study revealed that SGK3 plays a pivotal role in Akt/protein kinase B independent signaling downstream of oncogenic PI3KCA mutations in breast cancer. Here we report that SGK3 is an estrogen receptor (ER) transcriptional target and promotes estrogen-mediated cell survival of ER-positive breast cancer cells. Through a meta-analysis on 22 microarray studies of breast cancer in the Oncomine database, we found that the expression of SGK3 is significantly higher (5.7-fold, P < 0.001) in ER-positive tumors than in ER-negative tumors. In ER-positive breast cancer cells, SGK3 expression was found to be induced by 17β-estradiol (E2) in a dose- and time-dependent manner, and the induction of SGK3 mRNA by E2 is independent of newly synthesized proteins. We identified two ERα-binding regions at the sgk3 locus through chromatin immunoprecipitation with massively parallel DNA sequencing. Promoter analysis revealed that ERα stimulates the activity of sgk3 promoters by interaction with these two ERα-binding regions on E2 treatment. Loss-of-function analysis indicated that SGK3 is required for E2-mediated cell survival of MCF-7 breast carcinoma cells. Moreover, overexpression of SGK3 could partially protect MCF-7 cells against apoptosis caused by antiestrogen ICI 182,780. Together, our study defines the molecular mechanism of regulation of SGK3 by estrogen/ER and provides a new link between the PI3K pathway and ER signaling as well as a new estrogen-mediated cell survival mechanism mediated by SGK3 in breast cancer cells.

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