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Updated: Mar 9, 2026
Systems Biology of Metabolic Regulation by Estrogen Receptor Signaling in Breast Cancer
Published on: March 17, 2016
A Novel Functional Domain of Tab2 Involved in the Interaction with Estrogen Receptor Alpha in Breast Cancer Cells
Stefania Reineri1, Silvia Agati2, Valentina Miano1,3
1Department of Clinical and Biological Sciences, University of Turin, Turin, Italy.
Abstract:
Tab2, originally described as a component of the inflammatory pathway, has been implicated in phenomena of gene de-repression in several contexts, due to its ability to interact with the NCoR corepressor. Tab2 interacts also with steroid receptors and dismisses NCoR from antagonist-bound Estrogen and Androgen Receptors on gene regulatory regions, thus modifying their transcriptional activity and leading to pharmacological resistance in breast and prostate cancer cells. We demonstrated previously that either Tab2 knock-down, or a peptide mimicking the Estrogen Receptor alpha domain interacting with Tab2, restore the antiproliferative response to Tamoxifen in Tamoxifen-resistant breast cancer cells. In this work, we map the domain of Tab2 responsible of Estrogen Receptor alpha interaction. First, using both co-immunoprecipitation and pull-down with recombinant proteins, we found that the central part of Tab2 is primarily responsible for this interaction, and that this region also interacts with Androgen Receptor. Then, we narrowed down the essential interaction region by means of competition assays using recombinant protein pull-down. The interaction motif was finally identified as a small region adjacent to, but not overlapping, the Tab2 MEKK1 phosphorylation sites. A synthetic peptide mimicking this motif efficiently displaced Tab2 from interacting with recombinant Estrogen Receptor alpha in vitro, prompting us to test its efficacy using derivatives of the MCF7 breast carcinoma cell lines that are spontaneously resistant to Tamoxifen. Indeed, we observed that this mimic peptide, made cell-permeable by addition of the TAT minimal carrier domain, reduced the growth of Tamoxifen-resistant MCF7 cells in the presence of Tamoxifen. These data indicate a novel functional domain of the Tab2 protein with potential application in drug design.
Insights
Researchers identified a novel Tab2 protein domain that interacts with Estrogen Receptor alpha. A peptide mimicking this domain reduced growth in Tamoxifen-resistant breast cancer cells, suggesting new therapeutic strategies for cancer drug resistance.
Area of Science:
- Molecular Biology
- Cancer Research
- Endocrinology
Background:
- Tab2 protein, known for inflammatory pathways, also interacts with NCoR corepressor and steroid receptors.
- Tab2's interaction with Estrogen Receptor alpha (ERα) and Androgen Receptor (AR) influences transcriptional activity and contributes to drug resistance in breast and prostate cancers.
- Previous studies showed Tab2 knockdown or ERα-mimicking peptides restore anti-proliferative responses to Tamoxifen in resistant breast cancer cells.
Purpose of the Study:
- To map the specific domain of Tab2 responsible for its interaction with Estrogen Receptor alpha (ERα).
- To identify a novel functional motif within Tab2 for potential therapeutic targeting.
- To evaluate the efficacy of a peptide mimicking this motif in overcoming Tamoxifen resistance in breast cancer cells.
Main Methods:
- Co-immunoprecipitation and pull-down assays with recombinant proteins to identify the Tab2 region interacting with ERα and AR.
- Competition assays using recombinant proteins to narrow down the essential interaction motif within Tab2.
- In vitro assays with a synthetic peptide mimicking the identified motif and cell-based assays using Tamoxifen-resistant MCF7 breast carcinoma cell lines.
Main Results:
- The central region of Tab2 was identified as the primary interaction site for ERα and AR.
- A specific interaction motif, adjacent to but not overlapping MEKK1 phosphorylation sites, was pinpointed within Tab2.
- A cell-permeable peptide mimicking this motif effectively displaced Tab2 from ERα in vitro and reduced the growth of Tamoxifen-resistant MCF7 cells in the presence of Tamoxifen.
Conclusions:
- A novel functional domain within the Tab2 protein mediating ERα interaction has been characterized.
- A synthetic peptide mimicking this domain shows potential in overcoming Tamoxifen resistance in breast cancer.
- These findings suggest a new avenue for drug design targeting Tab2-ERα interactions to combat endocrine therapy resistance.
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