title: The SOX2-interactome in brain cancer cells identifies the requirement of MSI2 and USP9X for the growth of brain tumor cells.
abstract: Medulloblastomas and glioblastomas, the most common primary brain tumors in children and adults, respectively, are extremely difficult to treat. Efforts to identify novel proteins essential for the growth of these tumors may help to further our understanding of the biology of these tumors, as well as, identify targets for future therapies. The recent identification of multiple transcription factor-centric protein interaction landscapes in embryonic stem cells has identified numerous understudied proteins that are essential for the self-renewal of these stem cells. To identify novel proteins essential for the fate of brain tumor cells, we examined the protein interaction network of the transcription factor, SOX2, in medulloblastoma cells. For this purpose, Multidimensional Protein Identification Technology (MudPIT) identified >280 SOX2-associated proteins in the medulloblastoma cell line DAOY. To begin to understand the roles of SOX2-associated proteins in brain cancer, we focused on two SOX2-associated proteins, Musashi 2 (MSI2) and Ubiquitin Specific Protease 9x (USP9X). Recent studies have implicated MSI2, a putative RNA binding protein, and USP9X, a deubiquitinating enzyme, in several cancers, but not brain tumors. We demonstrate that knockdown of MSI2 significantly reduces the growth of DAOY cells as well as U87 and U118 glioblastoma cells. We also demonstrate that the knockdown of USP9X in DAOY, U87 and U118 brain tumor cells strongly reduces their growth. Together, our studies identify a large set of SOX2-associated proteins in DAOY medulloblastoma cells and identify two proteins, MSI2 and USP9X, that warrant further investigation to determine whether they are potential therapeutic targets for brain cancer.
authors.affiliation: Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.
authors.forename: Jesse L
authors.initials: JL
authors.lastname: Cox
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Wilder
authors.forename: Joshua M
authors.initials: JM
authors.lastname: Gilmore
authors.forename: Erin L
authors.initials: EL
authors.lastname: Wuebben
authors.forename: Michael P
authors.initials: MP
authors.lastname: Washburn
authors.forename: Angie
authors.initials: A
authors.lastname: Rizzino
mesh_terms: D000818:Animals; D001932:Brain Neoplasms / Q000473:pathology*; D060846:Cell Engineering; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival; D055785:Gene Knockdown Techniques; D051379:Mice; D011485:Protein Binding; D016601:RNA-Binding Proteins / Q000378:metabolism*; D055748:SOXB1 Transcription Factors / Q000378:metabolism*; D043222:Ubiquitin Thiolesterase / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*
chemical_list: C438151:MSI2 protein, human; D016601:RNA-Binding Proteins; C527782:SOX2 protein, human; D055748:SOXB1 Transcription Factors; C506234:USP9X protein, human; D043222:Ubiquitin Thiolesterase