Journal
BRITISH JOURNAL OF CANCER
Volume 98, Issue 6, Pages 1132-1140Publisher
NATURE PUBLISHING GROUP
DOI: 10.1038/sj.bjc.6604261
Keywords
Ebp1; PA2G4; phosphorylation; PAK1; breast cancer
Categories
Funding
- NCI NIH HHS [R01 CA76047, R01 CA076047] Funding Source: Medline
- PHS HHS [R21 088882-01] Funding Source: Medline
Ask authors/readers for more resources
The ErbB3 binding protein ( Ebp1) is a transcriptional corepressor that inhibits the activity of proliferation- associated genes and the growth of human breast cancer cell lines. Treatment of breast cancer cells with the ErbB3 ligand heregulin ( HRG) results in increased phosphorylation of Ebp1 and transcriptional repression. The p21- activated serine/ threonine kinase 1 ( PAK1), which plays an important role in breast cancer progression and resistance to the anti- oestrogen tamoxifen, is also activated by HRG. We therefore examined the ability of PAK1 to phosphorylate and regulate the function of Ebp1. We found that PAK1 phosphorylated Ebp1 in vitro and mapped the phosphorylation site to threonine 261. Both HRG treatment and expression of a constitutively activated PAK1 in MCF- 7 breast cancer cells enhanced threonine phosphorylation of Ebp1. In MCF- 7 cells, ectopically expressed Ebp1 bound endogenous PAK1 and this association was enhanced by treatment with HRG. Mutation of the PAK1 phosphorylation site to glutamic acid, mimicking a phosphorylated state, completely abrogated the ability of Ebp1 to repress transcription, inhibit growth of breast cancer cell lines and contribute to tamoxifen sensitivity. These studies demonstrate for the first time that Ebp1 is a substrate of PAK1 and the importance of the PAK1 phosphorylation site for the functional activity of Ebp1 in breast cancer cells.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available