title: TRIM28 interacts with EZH2 and SWI/SNF to activate genes that promote mammosphere formation.
abstract: Histone methyl transferase EZH2 (Enhancer of Zeste Homolog 2) is generally associated with H3K27 methylation and gene silencing, as a member of the polycomb repressor 2 (PRC2) complex. Immunoprecipitation and mass spectrometry of the EZH2-protein interactome in estrogen receptor positive, breast cancer-derived MCF7 cells revealed EZH2 interactions with subunits of chromatin remodeler SWI/SNF complex and TRIM28, which formed a complex with EZH2 distinct from PRC2. Unexpectedly, transcriptome profiling showed that EZH2 primarily activates, rather than represses, transcription in MCF7 cells and with TRIM28 co-regulates a set of genes associated with stem cell maintenance and poor survival of breast cancer patients. TRIM28 depletion repressed EZH2 recruitment to chromatin and expression of this gene set, in parallel with decreased CD44hi/CD24lomammosphere formation. Mammosphere formation, inhibited by EZH2 depletion, was rescued by ectopic expression of EZH2 but not by TRIM28 expression or by EZH2 mutated at the region (pre-SET domain) of TRIM28 interaction. These results support PRC2-independent functions of EZH2 and TRIM28 in activation of gene expression that promotes mammary stem cell enrichment and maintenance.
authors.affiliation: Genes and Development Graduate Program, The University of Texas Graduate School of Biomedical Sciences at Houston, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.|Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.|Center for Cancer Epigenetics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Surgery, University of Michigan School of Medicine, Ann Arbor, Michigan, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Xi
authors.affiliation: Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.|Center for Cancer Epigenetics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: W
authors.identifier: 0000-0001-9931-5990
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.|Center for Cancer Epigenetics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: R L
authors.initials: RL
authors.lastname: McCarthy
authors.affiliation: Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.|Center for Cancer Epigenetics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: S A
authors.initials: SA
authors.lastname: Stratton
authors.affiliation: Department of Surgery, University of Michigan School of Medicine, Ann Arbor, Michigan, USA.
authors.forename: W
authors.initials: W
authors.lastname: Zou
authors.affiliation: Department of Molecular and Cellular Biology, Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA.
authors.forename: W
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.|Center for Cancer Epigenetics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: S Y
authors.initials: SY
authors.lastname: Dent
authors.affiliation: Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.|Center for Cancer Epigenetics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: A K
authors.initials: AK
authors.lastname: Jain
authors.affiliation: Genes and Development Graduate Program, The University of Texas Graduate School of Biomedical Sciences at Houston, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.|Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.|Center for Cancer Epigenetics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: M C
authors.initials: MC
authors.lastname: Barton
mesh_terms: D001943:Breast Neoplasms / Q000235:genetics / Q000473:pathology*; D002448:Cell Adhesion / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics; D049109:Cell Proliferation / Q000235:genetics; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D000071221:Enhancer of Zeste Homolog 2 Protein / Q000378:metabolism*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D057809:HEK293 Cells; D006801:Humans; D061986:MCF-7 Cells; D014411:Neoplastic Stem Cells / Q000473:pathology / Q000502:physiology*; D011485:Protein Binding; D012097:Repressor Proteins / Q000378:metabolism*; D018874:Spheroids, Cellular / Q000378:metabolism / Q000473:pathology / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism*; D000076183:Tripartite Motif-Containing Protein 28; D014407:Tumor Cells, Cultured
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D012097:Repressor Proteins; C445179:SWI-SNF-B chromatin-remodeling complex; D014157:Transcription Factors; C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; C101116:TRIM28 protein, human; D000076183:Tripartite Motif-Containing Protein 28