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.

Identifying a TFIID interactome via integrated biochemical and high-throughput proteomic studies

“…This D1 peptide has strong homology to both Sox2 ( Figure 2) and TIF1A (Supplementary Figure 3A), which are transcriptional co-regulators [46,47]. Intriguingly, a recent study documented an interaction between Sox2 with TAF2 via immunopurification of Sox2 followed by MudPIT analysis [31], which is consistent with our D1-peptide label transfer results ( Figure 4A). We have also confirmed a direct interaction between Sox2 and TFIID using peer-reviewed) is the author/funder.…”

“…TAF2, 3, or 4) cross-linked to the SBED-labeled GST-peptides. However, a recent study using immunopurification of Sox2 followed by MudPIT analysis revealed an interaction between Sox2 with TAF2 [31]. It is thereby likely that the GST-D1 peptide contacts TAF2 in this experiment.…”

Musashi-2 promotes migration and invasion in bladder cancer via activation of the JAK2/STAT3 pathway

“…In addition, Msi2 isoform 2 appears to be the major isoform expressed in bladder cancer cell lines and tissues, which was consistent with the expression pattern of Msi2 in glioblastoma cells and embryonic stem cells. 18,19 Clinical analysis also indicated that high expression of Msi2 was correlated with poor overall and Msi2 promotes bladder cancer metastasis via JAK2/STAT3 pathway C Yang et al recurrence-free survival in patients with bladder cancer. Moreover, in vitro assays indicated that overexpression of Msi2 promoted, while silencing of Msi2 inhibited, the migration and invasiveness of bladder cancer cell through activating JAK2/STAT3 pathway.…”

“…Msi2 expression was negatively Msi2 promotes bladder cancer metastasis via JAK2/STAT3 pathway C Yang et al associated with AML patients outcome, 21 while the expression of NUMB, which was negatively regulated by Msi2 both in vitro and in vivo, 19 was not associated with overall survival in AML patients. 22 Mu et al 23 reported that high Msi2 expression could indicate poor prognosis in adult B-cell acute lymphoblastic leukemia.…”

Brain Tumor Treatment: 2017 Update

“…Alternatively, CSCs were identified in a murine brain tumor population by expressing EGFP under the control of nucleostemin promoter (a p53 mediate cell cycle modulator often expressed by highly proliferative cells) (Tamase, Muraguchi et al 2009). Furthermore, screening of BTSCs using flow-cytometry and Elisa have identified CD133, MMP-9, nestin, Pax6, Math-1, musashi-1, BMI-1, CXCR4, CX3CR1, c-Myc and Sox2 expressing BTSCs from both gliomas and medulloblastomas (Tamase, Muraguchi et al 2009, Cox, Wilder et al 2013, Sullivan, Nahed et al 2014). 1) High expression acts as an independent prognosis marker for malignant gliomas (Krogh Petersen, Jensen et al 2016).…”