Notch signaling regulates metabolic heterogeneity in glioblastoma stem cells.

Glioblastoma (GBM) stem cells (GSCs) reside in both hypoxic and vascular microenvironments within tumors. The molecular mechanisms that allow GSCs to occupy such contrasting niches are not understood. We used patient-derived GBM cultures to identify GSC subtypes with differential activation of Notch signaling, which co-exist in tumors but occupy distinct niches and match their metabolism accordingly. Multipotent GSCs with Notch pathway activation reside in perivascular niches, and are unable to entrain anaerobic glycolysis during hypoxia. In contrast, most CD133-expressing GSCs do not depend on canonical Notch signaling, populate tumors regardless of local vascularity and selectively utilize anaerobic glycolysis to expand in hypoxia. Ectopic activation of Notch signaling in CD133-expressing GSCs is sufficient to suppress anaerobic glycolysis and resistance to hypoxia. These findings demonstrate a novel role for Notch signaling in regulating GSC metabolism and suggest intratumoral GSC heterogeneity ensures metabolic adaptations to support tumor growth in diverse tumor microenvironments

Lineage-coupled clonal capture identifies clonal evolution mechanisms and vulnerabilities of BRAF

Targeted cancer therapies have revolutionized treatment but their efficacies are limited by the development of resistance driven by clonal evolution within tumors. We developed CAPTURE , a single-cell barcoding approach to comprehensively trace clonal dynamics and capture live lineage-coupled resistant cells for in-depth multi-omics analysis and functional exploration. We demonstrate that heterogeneous clones, either preexisting or emerging from drug-tolerant persister cells, dominated resistance to vemurafenib in BRA

Global Industry Reorganization and Market Concentration : Automobiles, Steel, and Airlines

Glioblastoma multiforme (GBM) is a deadly primary brain malignancy. Glioblastoma stem cells (GSC), which have the ability to self-renew and differentiate into tumor lineages, are believed to cause tumor recurrence due to their resistance to current therapies. A subset of GSCs is marked by cell surface expression of CD133, a glycosylated pentaspan transmembrane protein. The study of CD133-expressing GSCs has been limited by the relative paucity of genetic tools that specifically target them. Here, we present CD133-LV, a lentiviral vector presenting a single chain antibody against CD133 on its envelope, as a vehicle for the selective transduction of CD133-expressing GSCs. We show that CD133-LV selectively transduces CD133+ human GSCs in dose-dependent manner and that transduced cells maintain their stem-like properties. The transduction efficiency of CD133-LV is reduced by an antibody that recognizes the same epitope on CD133 as the viral envelope and by shRNA-mediated knockdown of CD133. Conversely, the rate of transduction by CD133-LV is augmented by overexpression of CD133 in primary human GBM cultures. CD133-LV selectively transduces CD133-expressing cells in intracranial human GBM xenografts in NOD.SCID mice, but spares normal mouse brain tissue, neurons derived from human embryonic stem cells and primary human astrocytes. Our findings indicate that CD133-LV represents a novel tool for the selective genetic manipulation of CD133-expressing GSCs, and can be used to answer important questions about how these cells contribute to tumor biology and therapy resistance

Multiple modes of PRC2 inhibition elicit global chromatin alterations in H3K27M pediatric glioma

A methionine substitution at lysine-27 on histone H3 variants (H3K27M) characterizes ~80% of diffuse intrinsic pontine gliomas (DIPG) and inhibits polycomb repressive complex 2 (PRC2) in a dominant-negative fashion. Yet, the mechanisms for this inhibition and abnormal epigenomic landscape have not been resolved. Using quantitative proteomics, we discovered that robust PRC2 inhibition requires levels of H3K27M greatly exceeding those of PRC2, seen in DIPG. While PRC2 inhibition requires interaction with H3K27M, we found that this interaction on chromatin is transient, with PRC2 largely being released from H3K27M. Unexpectedly, inhibition persisted even after PRC2 dissociated from H3K27M-containing chromatin, suggesting a lasting impact on PRC2. Furthermore, allosterically activated PRC2 is particularly sensitive to H3K27M, leading to the failure to spread H3K27me from PRC2 recruitment sites and consequently abrogating PRC2's ability to establish H3K27me2-3 repressive chromatin domains. In turn, levels of polycomb antagonists such as H3K36me2 are elevated, suggesting a more global, downstream effect on the epigenome. Together, these findings reveal the conditions required for H3K27M-mediated PRC2 inhibition and reconcile seemingly paradoxical effects of H3K27M on PRC2 recruitment and activity

Adult Primary Spinal Epidural Extraosseous Ewing’s Sarcoma: A Case Report and Review of the Literature

Background. Extraosseous Ewing’s sarcoma in the spinal epidural space is a rare malignancy, especially in adults. Case Presentation. A 40-year-old male presented with back pain and urinary hesitancy. MRI revealed a thoracic extradural mass with no osseous involvement. He underwent surgery for gross total resection of the mass, which was diagnosed as Ewing’s sarcoma. He was subsequently treated with chemoradiotherapy. He remains disease-free 1 year after surgery. Review of the literature indicated only 45 previously reported cases of spinal epidural extraosseous Ewing’s sarcoma in adults. Conclusions. Extraosseous Ewing’s sarcoma in the spinal epidural space is a rare clinical entity that should be included in the differential for spinal epidural masses. Its treatment is multidisciplinary but frequently requires surgical intervention due to compressive neurologic symptoms. Gross total resection appears to correlate with improved outcomes

Preplanning prediction of the left anterior descending artery maximum dose based on patient, dosimetric, and treatment planning parameters

Purpose: Maximum dose to the left anterior descending artery (LADmax) is an important physical constraint to reduce the risk of cardiovascular toxicity. We generated a simple algorithm to guide the positioning of the tangent fields to reliably maintain LADmax <10 Gy. Methods and materials: Dosimetric plans from 146 consecutive women treated prone to the left breast enrolled in prospective protocols of accelerated whole breast radiation therapy, with a concomitant daily boost to the tumor bed (40.5 Gy/15 fraction to the whole breast and 48 Gy to the tumor bed), provided the training set for algorithm development. Scatter plots and correlation coefficients were used to describe the bivariate relationships between LADmax and several parameters: distance from the tumor cavity to the tangent field edge, cavity size, breast separation, field size, and distance from the tangent field. A logistic sigmoid curve was used to model the relationship of LADmax and the distance from the tangent field. Furthermore, we tested this prediction model on a validation data set of 53 consecutive similar patients. Results: A lack of linear relationships between LADmax and distance from cavity to LAD (−0.47), cavity size (−0.18), breast separation (−0.02), or field size (−0.28) was observed. In contrast, distance from the tangent field was highly negatively correlated to LADmax (-0.84) and was used in the models to predict LADmax. From a logistic sigmoid model we selected a cut-point of 2.46 mm (95% confidence interval, 2.19-2.74 mm) greater than which LADmax is <10 Gy (95% confidence interval, 9.30-10.72 Gy) and LADmean is <3.3 Gy. Conclusions: Placing the edge of the tangents at least 2.5 mm from the closest point of the contoured LAD is likely to assure LADmax is <10 Gy and LADmean is <3.3 Gy in patients treated with prone accelerated breast radiation therapy

CD133-LV transduces CD133+ cells in primary GBM xenografts in the mouse brain.

<p><b>A</b>. Intracranial xenograft tumors were generated using injection of GBML20 cells (5×10⁵ cells/animal) and tumor formation (red circle) was confirmed with small animal MRI 1.5 months after injection. High titer stocks of CD133-LV or VSVG-LV expressing TagBFP were injected into the tumor and animals were sacrificed 7 days later for immunofluorescence analysis. <b>B</b>. CD133-LV - transduced cells expressing TagBFP (red) show cell surface immunoreactivity for CD133 (green). <b>C</b>. CD133+ cells were significantly more enriched among TagBFP+ transduced cells in the case of CD133-LV compared to VSVG-LV.</p

CD133-LV transduces CD133+ cells in primary human GBM cultures <i>in vitro</i>.

<p><b>A</b>. Plasma membrane topology of CD133. CD133-LV recognizes an epitope on the second extracellular loop of the glycoprotein. <b>B</b>. Envelope protein of CD133-LV (Hmut: mutant hemagglutinin, 141.7Fv: single chain antibody against 293C3 epitope on second extracellular loop of CD133). Hmut and 141.7Fv are separated by a linker peptide. <b>C</b>. Observations collected from 3 primary GBM cultures. <b>i</b>. Primary GBM cultures are maintained as tumorspheres in suspension using media supplemented with EGF and bFGF. <b>ii</b>. Cell surface CD133 expression varies among different GBM lines, as assayed by flow cytometry. <b>iii,iv</b>. Flow cytometric analysis of transduction efficiency with CD133-LV (<b>iii</b>) and VSVG-LV (<b>iv</b>) expressing TagBFP. <b>D</b>. CD133-LV transduction efficiency correlates with the CD133 content of three primary GBM cultures (MOI = 5). <b>E</b>. Fluorescent microscopy shows a human GBM tumorsphere with scattered cells transduced with CD133-LV and thereby expressing TagBFP. This image was taken three days after incubation of cells with CD133-LV. <b>F</b>. Transduction of GBML3 cultures (CD133 content is 1.7±0.1%) with CD133-LV is dose-dependent and transduction efficiency is significantly lower than with pantropic VSVG-LV.</p