title: Efp targets 14-3-3 sigma for proteolysis and promotes breast tumour growth.
abstract: Oestrogen exerts its influence on target organs through activating oestrogen receptors (ERs) and regulating downstream genes by means of their oestrogen-responsive elements. Efp, a target gene product of ER alpha, is a member of the RING-finger B-box coiled-coil (RBCC) motif family. Efp is predominantly expressed in various female organs as well as in breast cancers, and is thought to be essential for oestrogen-dependent cell proliferation and organ development Efp-disrupted mice display underdeveloped uteri and reduced oestrogen responsiveness. Here we show that Efp is a RING-finger-dependent ubiquitin ligase (E3) that targets proteolysis of 14-3-3 sigma, a negative cell cycle regulator that causes G2 arrest. We demonstrate that tumour growth of breast cancer MCF7 cells implanted in female athymic mice is reduced by treatment with antisense Efp oligonucleotide. Efp-overexpressing MCF7 cells in ovariectomized athymic mice generate tumours in the absence of oestrogen. Loss of Efp function in mouse embryonic fibroblasts results in an accumulation of 14-3-3 sigma, which is responsible for reduced cell growth. These data provide an insight into the cell-cycle machinery and tumorigenesis of breast cancer by identifying 14-3-3 sigma as a target for proteolysis by Efp, leading to cell proliferation.
authors.affiliation: Department of Geriatric Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Urano
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Saito
authors.forename: Tohru
authors.initials: T
authors.lastname: Tsukui
authors.forename: Masayo
authors.initials: M
authors.lastname: Fujita
authors.forename: Takayuki
authors.initials: T
authors.lastname: Hosoi
authors.forename: Masami
authors.initials: M
authors.lastname: Muramatsu
authors.forename: Yasuyoshi
authors.initials: Y
authors.lastname: Ouchi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Inoue
mesh_terms: D048948:14-3-3 Proteins; D000818:Animals; D014408:Biomarkers, Tumor; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D019556:COS Cells; D002453:Cell Cycle; D002455:Cell Division; D003546:Cysteine Endopeptidases / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004967:Estrogens / Q000494:pharmacology; D005092:Exonucleases; D005095:Exoribonucleases; D005260:Female; D017353:Gene Deletion; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D008025:Ligases / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009097:Multienzyme Complexes / Q000378:metabolism; D009363:Neoplasm Proteins; D009368:Neoplasm Transplantation; D011233:Precipitin Tests; D046988:Proteasome Endopeptidase Complex; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D020798:Two-Hybrid System Techniques; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases
chemical_list: D048948:14-3-3 Proteins; D014408:Biomarkers, Tumor; D004268:DNA-Binding Proteins; D004967:Estrogens; D009097:Multienzyme Complexes; D009363:Neoplasm Proteins; D011506:Proteins; D014157:Transcription Factors; C490034:Trim25 protein, mouse; D025801:Ubiquitin; D044767:Ubiquitin-Protein Ligases; D005092:Exonucleases; D005095:Exoribonucleases; C413442:SFN protein, human; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D008025:Ligases