scholarly journals Activation of Mitogen-Activated Protein Kinase in Estrogen Receptor α–Positive Breast Cancer Cells In vitro Induces an In vivo Molecular Phenotype of Estrogen Receptor α–Negative Human Breast Tumors

2006 ◽  
Vol 66 (7) ◽  
pp. 3903-3911 ◽  
Author(s):  
Chad J. Creighton ◽  
Amy M. Hilger ◽  
Shalini Murthy ◽  
James M. Rae ◽  
Arul M. Chinnaiyan ◽  
...  
Keyword(s):  
Estrogen Receptor ◽  
Breast Cancer Cells ◽  
Estrogen Receptor Α ◽  
Mitogen Activated Protein Kinase ◽  
Human Breast ◽  
Molecular Phenotype ◽  
Mitogen Activated Protein ◽  
Positive Breast Cancer

scholarly journals AIB1 Is a Conduit for Kinase-Mediated Growth Factor Signaling to the Estrogen Receptor

2000 ◽  
Vol 20 (14) ◽  
pp. 5041-5047 ◽  
Author(s):  
Jaime Font de Mora ◽  
Myles Brown
Keyword(s):  
Estrogen Receptor ◽  
Growth Factors ◽  
Growth Factor ◽  
Mitogen Activated Protein Kinase ◽  
Growth Factor Signaling ◽  
Breast Cancers ◽  
Mapk Activation ◽  
Mitogen Activated Protein

ABSTRACT Growth factor modulation of estrogen receptor (ER) activity plays an important role in both normal estrogen physiology and the pathogenesis of breast cancer. Growth factors are known to stimulate the ligand-independent activity of ER through the activation of mitogen-activated protein kinase (MAPK) and the direct phosphorylation of ER. We found that the transcriptional activity of AIB1, a ligand-dependent ER coactivator and a gene amplified preferentially in ER-positive breast cancers, is enhanced by MAPK phosphorylation. We demonstrate that AIB1 is a phosphoprotein in vivo and can be phosphorylated in vitro by MAPK. Finally, we observed that MAPK activation of AIB1 stimulates the recruitment of p300 and associated histone acetyltransferase activity. These results suggest that the ability of growth factors to modulate estrogen action may be mediated through MAPK activation of the nuclear receptor coactivator AIB1.

scholarly journals Phosphorylation at serines 104 and 106 by Erk1/2 MAPK is important for estrogen receptor-α activity

2008 ◽  
Vol 40 (4) ◽  
pp. 173-184 ◽  
Author(s):  
Ross S Thomas ◽  
Naveed Sarwar ◽  
Fladia Phoenix ◽  
R Charles Coombes ◽  
Simak Ali
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Activation Function ◽  
Estrogen Receptor Α ◽  
Mitogen Activated Protein Kinase ◽  
Breast Cancer Patients ◽  
Independent Manner ◽  
Stimulation Of

Phosphorylation of estrogen receptor-α (ERα) at specific residues in transcription activation function 1 (AF-1) can stimulate ERα activity in a ligand-independent manner. This has led to the proposal that AF-1 phosphorylation and the consequent increase in ERα activity could contribute to resistance to endocrine therapies in breast cancer patients. Previous studies have shown that serine 118 (S118) in AF-1 is phosphorylated by extracellular signal-regulated kinases 1 and 2 (Erk1/2) mitogen-activated protein kinase (MAPK) in a ligand-independent manner. Here, we show that serines 104 (S104) and 106 (S106) are also phosphorylated by MAPK in vitro and upon stimulation of MAPK activity in vivo. Phosphorylation of S104 and S106 can be inhibited by the MAP-erk kinase (MEK)1/2 inhibitor U0126 and by expression of kinase-dead Raf1. Further, we show that, although S118 is important for the stimulation of ERα activity by the selective ER modulator 4-hydroxytamoxifen (OHT), S104 and S106 are also required for the agonist activity of OHT. Acidic amino acid substitution of S104 or S106 stimulates ERα activity to a greater extent than the equivalent substitution at S118, suggesting that phosphorylation at S104 and S106 is important for ERα activity. Collectively, these data indicate that the MAPK stimulation of ERα activity involves the phosphorylation not only of S118 but also of S104 and S106, and that MAPK-mediated hyperphosphorylation of ERα at these sites may contribute to resistance to tamoxifen in breast cancer.

Clomiphene Analogs with Activity In Vitro and In Vivo against Human Breast Cancer Cells

1998 ◽  
Vol 55 (6) ◽  
pp. 841-851 ◽  
Author(s):  
R.Jeffrey Baumann ◽  
Tammy L. Bush ◽  
Doreen E. Cross-Doersen ◽  
Elizabeth A. Cashman ◽  
Paul S. Wright ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Human Breast Cancer ◽  
Breast Cancer Cells ◽  
Human Breast Cancer Cells ◽  
Human Breast

scholarly journals Role for the Ran Binding Protein, Mog1p, in Saccharomyces cerevisiae SLN1-SKN7 Signal Transduction

2004 ◽  
Vol 3 (6) ◽  
pp. 1544-1556 ◽  
Author(s):  
Jade Mei-Yeh Lu ◽  
Robert J. Deschenes ◽  
Jan S. Fassler
Keyword(s):  
Signal Transduction ◽  
Transcription Factor ◽  
Osmotic Stress ◽  
Kinase Activity ◽  
Mitogen Activated Protein Kinase ◽  
Osmotic Response ◽  
Mitogen Activated Protein ◽  
Kinase Pathway

ABSTRACT Yeast Sln1p is an osmotic stress sensor with histidine kinase activity. Modulation of Sln1 kinase activity in response to changes in the osmotic environment regulates the activity of the osmotic response mitogen-activated protein kinase pathway and the activity of the Skn7p transcription factor, both important for adaptation to changing osmotic stress conditions. Many aspects of Sln1 function, such as how kinase activity is regulated to allow a rapid response to the continually changing osmotic environment, are not understood. To gain insight into Sln1p function, we conducted a two-hybrid screen to identify interactors. Mog1p, a protein that interacts with the yeast Ran1 homolog, Gsp1p, was identified in this screen. The interaction with Mog1p was characterized in vitro, and its importance was assessed in vivo. mog1 mutants exhibit defects in SLN1-SKN7 signal transduction and mislocalization of the Skn7p transcription factor. The requirement for Mog1p in normal localization of Skn7p to the nucleus does not fully account for the mog1-related defects in SLN1-SKN7 signal transduction, raising the possibility that Mog1p may play a role in Skn7 binding and activation of osmotic response genes.

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