title: A Novel Functional Domain of Tab2 Involved in the Interaction with Estrogen Receptor Alpha in Breast Cancer Cells.
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.
authors.affiliation: Department of Clinical and Biological Sciences, University of Turin, Turin, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Reineri
authors.affiliation: Bioindustry Park Silvano Fumero, Colleretto Giacosa, Turin, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Agati
authors.affiliation: Department of Clinical and Biological Sciences, University of Turin, Turin, Italy.|Center for Molecular Systems Biology, University of Turin, Turin, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Miano
authors.affiliation: CNR, i.c.r.m. Institute of Chemistry of Molecular Recognition, Milan, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Sani
authors.affiliation: Department of Clinical and Biological Sciences, University of Turin, Turin, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Berchialla
authors.affiliation: Department of Clinical and Biological Sciences, University of Turin, Turin, Italy.|Bioindustry Park Silvano Fumero, Colleretto Giacosa, Turin, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Ricci
authors.affiliation: Department of Clinical and Biological Sciences, University of Turin, Turin, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Iannello
authors.affiliation: Department of Clinical and Biological Sciences, University of Turin, Turin, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Coscujuela Tarrero
authors.affiliation: Department of Clinical and Biological Sciences, University of Turin, Turin, Italy.|Center for Molecular Systems Biology, University of Turin, Turin, Italy.
authors.forename: Santina
authors.initials: S
authors.lastname: Cutrupi
authors.affiliation: Department of Clinical and Biological Sciences, University of Turin, Turin, Italy.|Center for Molecular Systems Biology, University of Turin, Turin, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: De Bortoli
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D020816:Amino Acid Motifs; D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000235:genetics; D047628:Estrogen Receptor alpha / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006801:Humans; D061986:MCF-7 Cells; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000235:genetics / Q000494:pharmacology; D000072417:Protein Domains; D013629:Tamoxifen / Q000494:pharmacology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C506487:ESR1 protein, human; D047628:Estrogen Receptor alpha; D009363:Neoplasm Proteins; D010455:Peptides; C410585:TAB2 protein, human; D013629:Tamoxifen