Project description:Glioblastoma is one of the most malignant brain tumors with poor prognosis and their development and progression are known to be driven by glioblastoma stem cells. Although glioblastoma stem cells lose their cancer stemness properties during cultivation in serum-containing medium, little is known about the molecular mechanisms regulating signaling alteration in relation to reduction of stemness. In order to elucidate the global phosphorylation-related signaling events, we performed a SILAC-based quantitative phosphoproteome analysis of serum-induced dynamics in glioblastoma stem cells established from the tumor tissues of the patient. Among a total of 2,876 phosphorylation sites on 1,584 proteins identified in our analysis, 732 phosphorylation sites on 419 proteins were regulated through the alteration of stem cell characteristics.
Project description:The key role of RNA-binding proteins (RBPs) in posttranscriptional regulation of gene expression is intimately tied to their subcellular localization. Dysregulated localization may severely disrupt the biological functions of RBPs. To reveal the regulatory mechanisms of RBPs, methods for systematically mapping the subcellular localized RBPs and monitoring their translocations under physiological conditions are in high demand. Herein, a subcellular-specific RNA labeling method was developed for efficient enrichment and deep profiling of nuclear and cytoplasmic RBPs. A total of 1221 nuclear RBPs and 1333 cytoplasmic RBPs were enriched and identified using nuclear/cytoplasm targeting enrichment probes, which represented an increase of 54.4% and 85.7% compared with previous reports. The probes were further applied in the first omics-level investigation of subcellular-specific RBP-RNA interactions upon ferroptosis induction. Interestingly, large-scale RBPs displayed enhanced interaction with RNAs in nucleus but reduced association with RNAs in cytoplasm during ferroptosis process. Among these RBPs with regulated RNA-binding, translation was found as one of the commonly enriched GO functions by different ferroptosis inducers, indicating ferroptosis could disturb protein translation via different pathways. Furthermore, we discovered dozens of nucleoplasmic translocation candidate RBPs upon ferroptosis induction and validated representative ones by immunofluorescence imaging. The enrichment of TCA cycle in the translocation candidate RBPs may provide new insights for investigating their possible roles in ferroptosis induced metabolism dysregulation. The above findings suggest the potential of our enrichment method for high-throughput RBP mapping with organelle-level spatial resolution.
Project description:Kruppel-like factor-9 (KLF9), a member of the large KLF transcription factor family, has emerged as a regulator of oncogenesis, cell differentiation and neural development; however, the molecular basis for KLF9M-bM-^@M-^Ys diverse contextual functions remains unclear. This study focuses on the functions of KLF9 in human glioblastoma stem-like cells. We establish for the first time a genome-wide map of KLF9-regulated targets in human glioblastoma stem-like cells, and show that KLF9 functions as a transcriptional repressor and thereby regulates multiple signaling pathways involved in oncogenesis and stem cell regulation. A detailed analysis of one such pathway, integrin signaling, shows that the capacity of KLF9 to inhibit glioblastoma cell stemness and tumorigenicity requires ITGA6 repression. These findings enhance our understanding of the transcriptional networks underlying cancer cell stemness and differentiation, and identify KLF9-regulated molecular targets applicable to cancer therapeutics. Two cell lines were used as biological replicates. Each cell line has one KLF9 induction sample and one control sample.
Project description:Acquired and primary therapy resistance remain a major hurdle in clinical treatment of multiple myeloma (MM). Despite the availability of broad spectrum anti-cancer drugs, most MM patients eventually relapse and become refractory to current treatments. Therefore, we explored whether therapy-resistant MM cells are sensitive to ferroptosis induction, an iron-catalyzed mode of cell death associated with increased lipid peroxidation. In this study, we exposed glucocorticoid-resistant MM1R and glucocorticoid-sensitive MM1S cells to ferroptosis inducers RSL3 and evaluated their transcriptional changes via RNA sequencing. Compared to untreated controls, ferroptotic RSL3-treated cells displayed a significant upregulation of genes involved in inflammation, kinase signaling, cellular stress, and cell death pathways. Pre-treatment with ferroptosis inhibitor Fer-1 partly reverted these RSL3-induced transcriptional changes and revealed that especially genes involved in metal binding, nuclear receptor signaling, chromatin remodeling, and gene transcription regulation are pivotal for ferroptosis induction. Overall, these findings suggest that ferroptosis effectively targets MM1 cells and that RSL3-mediated ferroptosis triggers similar oxidative stress and cell death pathways in both MM1R and MM1S cells, irrespective of their glucocorticoid-sensitivity status.
Project description:Chromatin accessibility discriminates stem from mature cell populations, enabling the identification of primitive stem-like cells in primary tumors, such as Glioblastoma (GBM) where self-renewing cells driving cancer progression and recurrence are prime targets for therapeutic intervention. We show, using single-cell chromatin accessibility, that primary GBMs harbor a heterogeneous self-renewing population whose diversity is captured in patient-derived glioblastoma stem cells (GSCs). In depth characterization of chromatin accessibility in GSCs identifies three GSC states: Reactive, Constructive, and Invasive, each governed by uniquely essential transcription factors and present within GBMs in varying proportions. Orthotopic xenografts reveal that GSC states associate with survival, and identify an invasive GSC signature predictive of low patient survival. Our chromatin-driven characterization of GSC states improves prognostic precision and identifies dependencies to guide combination therapies.