title: A transcriptional repressive role for epithelial-specific ETS factor ELF3 on oestrogen receptor alpha in breast cancer cells.
abstract: Oestrogen receptor-α (ERα) is a ligand-dependent transcription factor that primarily mediates oestrogen (E2)-dependent gene transcription required for mammary gland development. Coregulators critically regulate ERα transcription functions by directly interacting with it. In the present study, we report that ELF3, an epithelial-specific ETS transcription factor, acts as a transcriptional repressor of ERα. Co-immunoprecipitation (Co-IP) analysis demonstrated that ELF3 strongly binds to ERα in the absence of E2, but ELF3 dissociation occurs upon E2 treatment in a dose- and time-dependent manner suggesting that E2 negatively influences such interaction. Domain mapping studies further revealed that the ETS (E-twenty six) domain of ELF3 interacts with the DNA binding domain of ERα. Accordingly, ELF3 inhibited ERα's DNA binding activity by preventing receptor dimerization, partly explaining the mechanism by which ELF3 represses ERα transcriptional activity. Ectopic expression of ELF3 decreases ERα transcriptional activity as demonstrated by oestrogen response elements (ERE)-luciferase reporter assay or by endogenous ERα target genes. Conversely ELF3 knockdown increases ERα transcriptional activity. Consistent with these results, ELF3 ectopic expression decreases E2-dependent MCF7 cell proliferation whereas ELF3 knockdown increases it. We also found that E2 induces ELF3 expression in MCF7 cells suggesting a negative feedback regulation of ERα signalling in breast cancer cells. A small peptide sequence of ELF3 derived through functional interaction between ERα and ELF3 could inhibit DNA binding activity of ERα and breast cancer cell growth. These findings demonstrate that ELF3 is a novel transcriptional repressor of ERα in breast cancer cells. Peptide interaction studies further represent a novel therapeutic option in breast cancer therapy.
authors.affiliation: Molecular and Cellular Oncology Laboratory, Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad 500046, Telangana, India.
authors.forename: Vijaya Narasihma Reddy
authors.initials: VN
authors.lastname: Gajulapalli
authors.affiliation: Molecular and Cellular Oncology Laboratory, Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad 500046, Telangana, India.
authors.forename: Venkata Subramanyam Kumar
authors.initials: VS
authors.lastname: Samanthapudi
authors.affiliation: Department of Biochemistry, Sri Krishnadevaraya University, Anantapur 515003, Andhra Pradesh, India.
authors.forename: Madhusudana
authors.initials: M
authors.lastname: Pulaganti
authors.affiliation: Molecular and Cellular Oncology Laboratory, Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad 500046, Telangana, India.
authors.forename: Saratchandra Singh
authors.initials: SS
authors.lastname: Khumukcham
authors.affiliation: Department of Biotechnology, Acharya Nagarjuna University, Guntur, Andhra Pradesh, India.
authors.forename: Vijaya Lakhsmi
authors.initials: VL
authors.lastname: Malisetty
authors.affiliation: School of Chemistry, University of Hyderabad, Hyderabad 500046, Telangana, India.
authors.forename: Lalitha
authors.initials: L
authors.lastname: Guruprasad
authors.affiliation: Department of Biochemistry, Sri Krishnadevaraya University, Anantapur 515003, Andhra Pradesh, India.
authors.forename: Suresh Kumar
authors.initials: SK
authors.lastname: Chitta
authors.affiliation: Molecular and Cellular Oncology Laboratory, Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad 500046, Telangana, India manavathibsl@uohyd.ernet.in.
authors.forename: Bramanandam
authors.initials: B
authors.lastname: Manavathi
mesh_terms: D000595:Amino Acid Sequence; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects / Q000502:physiology; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D047628:Estrogen Receptor alpha / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005260:Female; D006367:HeLa Cells; D006801:Humans; D061986:MCF-7 Cells; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D050783:Proto-Oncogene Proteins c-ets / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013629:Tamoxifen / Q000378:metabolism / Q000494:pharmacology; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; C105529:ELF3 protein, human; C506487:ESR1 protein, human; D047628:Estrogen Receptor alpha; D050783:Proto-Oncogene Proteins c-ets; D014157:Transcription Factors; D013629:Tamoxifen
keywords: breast cancer; epithelial-specific ETS transcription factor-1 (ESE1/ELF3); oestrogen receptor alpha; transcriptional repression