Project description:Circular RNAs are single-stranded covalently closed non-coding RNAs expressed in a variety of tissues and cells. Glioblastoma (GBM) is the most aggressive and lethal tumor in the central nervous system, characterized by high recurrence and mortality rates. Here we explore circRNA expression profiles in 26 primary and 3 recurrent GBM samples and compare them to healthy brain tissue. Additionally we compare expression of circRNA in GBM patients blood in comparison to healthy donor blood.
Project description:Despite the progress in medicine, no significant advancement in the standard of care for glioblastoma (GBM) patients have been reached. GBM heterogeneity, poor blood–brain barrier penetration and resistance to therapy highlight the need for new targets and clinical treatments. A step toward clinical translation includes the eradication of GBM Tumor-Initiating Cells (TICs), responsible for GBM heterogeneity and relapse. By using patient-derived TICs and xenograft orthotopic models, we demonstrate that Lysine-specific histone demethylase 1A (LSD1) is a druggable target in GBM. Here, we analyze the effect of LSD1i treatment on histone H3K4 in primary human cells and mouse brains.
Project description:Glioblastoma multiforme (GBM), a highly malignant and heterogeneous brain tumor, contains various types of tumor and non-tumor cells. Whether GBM cells can trans-differentiate into non-neural cell types, including mural cells or endothelial cells, to support tumor growth and invasion remains controversial. Here we generated two genetic GBM models de novo in immunocompetent mouse brains, mimicking essential pathological and molecular features of human GBMs. Single-cell RNA sequencing showed that patterns of copy-number variations (CNVs) of mural cells and endothelial cells were distinct from those of GBM cells, indicating discrete origins of GBM cells and vascular components. Furthermore, lineage tracing and transplantation studies demonstrated that, although blood vessels in GBM brains underwent drastic remodeling, GBM cells did not give rise to non-neural cell types in the brain. Intriguingly, GBM cells could randomly express mesenchymal markers, including those for mural cells, during gliomagenesis. Most importantly, single-cell CNV analysis of human GBM specimens also strongly suggested that GBM cells and vascular cells are separate lineages. Instead, non-neural cell types expanded by proliferation during tumorigenesis. Therefore, cross-lineage trans-differentiation of GBM cells is very unlikely to occur during gliomagenesis. Our findings advance understanding of cell lineage dynamics during gliomagenesis, and have implications for targeted treatment of GBMs.
Project description:Glioblastoma multiforme (GBM), a highly malignant and heterogeneous brain tumor, contains various types of tumor and non-tumor cells. Whether GBM cells can trans-differentiate into non-neural cell types, including mural cells or endothelial cells, to support tumor growth and invasion remains controversial. Here we generated two genetic GBM models de novo in immunocompetent mouse brains, mimicking essential pathological and molecular features of human GBMs. Single-cell RNA sequencing showed that patterns of copy-number variations (CNVs) of mural cells and endothelial cells were distinct from those of GBM cells, indicating discrete origins of GBM cells and vascular components. Furthermore, lineage tracing and transplantation studies demonstrated that, although blood vessels in GBM brains underwent drastic remodeling, GBM cells did not give rise to non-neural cell types in the brain. Intriguingly, GBM cells could randomly express mesenchymal markers, including those for mural cells, during gliomagenesis. Most importantly, single-cell CNV analysis of human GBM specimens also strongly suggested that GBM cells and vascular cells are separate lineages. Instead, non-neural cell types expanded by proliferation during tumorigenesis. Therefore, cross-lineage trans-differentiation of GBM cells is very unlikely to occur during gliomagenesis. Our findings advance understanding of cell lineage dynamics during gliomagenesis, and have implications for targeted treatment of GBMs.
Project description:Comparative expression analysis of RNA isolated from microvesicles from serum from glioblastoma multiforme (GBM) patients and normal healthy individuals. Blood samples from 9 patients diagnosed with de-novo primary GBM were collected immediately prior to surgery. Blood from 7 normal healthy controls was collected from volunteers recruited at the MGH blood bank. From each sample, RNA was isolated from microvesicles isolated from 1 mL of serum, and the RNA was linearly amplified and labeled with Cy3. The amplified and labeled RNA was hybridized to 16 individual Agilent Arrays.
Project description:Here, by mapping H3K27ac deposition, we analyze the active regulatory landscapes across primary GBM biopsies, normal brain tissues, and cell line counterparts. Analysis of differentially regulated enhancers, especially super-enhancers between GBM and normal brain tissues, as well as among GBM samples with matched RNA-sequencing data, uncovered unrecognized layers of oncogenic core transcriptional dependency and inter-tumor heterogeneity. Moreover, we demonstrate the functional relevance of leading candidates of super-enhancer-driven transcriptional factors, long non-coding RNAs, and druggable targets in GBM. Through profiling of transcriptional enhancers, our integrative study provides clinically relevant insights into GBM molecular classification, pathogenesis, and therapeutic innovations.
Project description:Glioblastoma (GBM) is the most common and most aggressive primary brain tumor in adults. The existence of a small population of stem-like tumor cells that efficiently propagate tumors and resist cytotoxic therapy is one proposed mechanism leading to the resilient behavior of tumor cells and poor prognosis. In this study, we performed an in-depth analysis of the DNA methylation landscape in GBM-derived cancer stem cells (GSCs). Parallel comparisons of primary tumors and GSC lines derived from these tumors with normal controls (a neural stem cell (NSC) line and normal brain tissue) identified groups of hyper- and hypomethylated genes that display a trend of either increasing or decreasing methylation levels in the order of controls, primary GBMs, and their counterpart GSC lines, respectively. Interestingly, concurrent promoter hypermethylation and gene body hypomethylation were observed in a subset of genes including MGMT, AJAP1 and PTPRN2. These unique DNA methylation signatures were also found in primary GBM-derived xenograft tumors indicating that they are not tissue culture-related epigenetic changes. Integration of GSC-specific epigenetic signatures with gene expression analysis further identified candidate tumor suppressor genes that are frequently down regulated in GBMs such as SPINT2, NEFM and PENK. Forced re-expression of SPINT2 reduced glioma cell proliferative capacity, anchorage independent growth, cell motility, and tumor sphere formation in vitro. The results from this study demonstrate that GSCs possess unique epigenetic signatures that may play important roles in the pathogenesis of GBM. The reduced representation bisulfite sequencing (RRBS) approach (Meissner et al., 2008) was used to generate genome-wide single-base resolution CpG methylation profiles of three primary GBMs (1063T, 1133T, and 1142T) and three GSC lines (1063S, 1133S, 1142S) derived from these primary GBM tumors. The NSC line and the normal brain (NB) tissue sample were used as controls for comparison purposes. In addition, we analyzed three GBM xenograft tumor tissue samples (Mayo22, Mayo39, Mayo59) developed by Dr. Jann N. Sarkaria of Mayo Clinic.
Project description:Purpose: Glioblastoma (GBM) is highly resistant to treatment, largely due to disease heterogeneity and resistance mechanisms. We sought to investigate a promising drug that can inhibit multiple aspects of cancer cell survival mechanisms and become effective therapeutics for GBM patients. Experimental Design: To investigate TG02, an agent with known penetration of the Blood-Brain Barrier, we examined the effects as single agent and in combination with temozolomide, a commonly used chemotherapy in GBM. We utilized human GBM cells and a syngeneic mouse orthotopic GBM model, evaluating survival and the pharmacodynamics of TG02. Mechanistic studies included TG02-induced transcriptional regulation, apoptosis and RNA sequencing in treated GBM cells as well as the investigation of mitochondrial and glycolytic function assays. Results: We demonstrated that TG02 inhibited cell proliferation, induced cell death, and synergized with temozolomide in GBM cells with different genetic background but not in astrocytes. TG02-induced cytotoxicity was blocked by the overexpression of phosphorylated CDK9, suggesting a CDK9-dependent cell killing. TG02 suppressed transcriptional progression of anti-apoptotic proteins, and induced apoptosis in GBM cells. We further demonstrated that TG02 caused mitochondrial dysfunction and glycolytic suppression and ultimately ATP depletion in GBM. A prolonged survival was observed in GBM mice receiving combined treatment of TG02 and temozolomide. The TG02-induced decrease of CDK9 phosphorylation was confirmed in the brain tumor tissue. Conclusions: TG02 inhibits multiple survival mechanisms and synergistically decreases energy production with temozolomide, representing a promising therapeutic strategy in GBM, currently under investigation in an ongoing clinical trial.
Project description:The purpose of this study is to determine whether the combination of two agents, INC280 and bevacizumab, is safe and effective when administered to patients with Glioblastoma Multiforme (GBM) who have progressed after receiving prior therapy or who have unresectable GBM.
Project description:Brain tumors, either primary or secondary, have limited therapeutic options despite advances in understanding tumor driving gene mutations and heterogeneity within tumor cells. The cellular and molecular composition of brain tumor stroma, an important modifier of tumor growth, has been less investigated and understood. Especially, studies focusing on brain tumor blood vessels are rare, yet, the brain endothelium and the blood-brain barrier (BBB) are the major obstacle for efficient drug delivery. In this study we have employed the RNA sequencing approach to get insights into transcriptional alterations of endothelial cells isolated from primary and secondary brain tumors. We used an immunoprecipitation approach to enrich for endothelial cells of normal brain, glioblastoma (GBM) and adenocarcinoma brain metastasis (BM). Analysis of the endothelial transcriptome showed that both the GBM and the BM vasculature showed deregulation of genes implicated in cell proliferation, angiogenesis, deposition of extracellular matrix (ECM), and deregulation of genes defining the BBB dysfunction module. We describe alterations in the BBB genes in the GBM and BM vasculature and identify proteins that could be exploited for developing drug delivery platforms into primary and secondary brain tumors. In addition, we identify deregulated expression of genes defining vessel-associated fibroblasts in the GBM tissue, highlighting that the cellular composition of the brain tumor stroma deserves further investigation.