Cryo-EM structure of human heptameric pannexin 2 channel.

Pannexin 2 (Panx2) is a large-pore ATP-permeable channel with critical roles in various physiological processes, such as the inflammatory response, energy production and apoptosis. Its dysfunction is related to numerous pathological conditions including ischemic brain injury, glioma and glioblastoma multiforme. However, the working mechanism of Panx2 remains unclear. Here, we present the cryo-electron microscopy structure of human Panx2 at a resolution of 3.4 Å. Panx2 structure assembles as a heptamer, forming an exceptionally wide channel pore across the transmembrane and intracellular domains, which is compatible with ATP permeation. Comparing Panx2 with Panx1 structures in different states reveals that the Panx2 structure corresponds to an open channel state. A ring of seven arginine residues located at the extracellular entrance forms the narrowest site of the channel, which serves as the critical molecular filter controlling the permeation of substrate molecules. This is further verified by molecular dynamics simulations and ATP release assays. Our studies reveal the architecture of the Panx2 channel and provide insights into the molecular mechanism of its channel gating.

Deletion of endothelial α-parvin inhibits tumour angiogenesis, reduces tumour growth and induces tumour cell apoptosis.

Alpha-parvin (α-pv), an adaptor protein that mediates integrin-dependent cell-matrix interactions, is essential for endothelial cells migration and proliferation and is a key player in physiological angiogenesis. The role of α-pv in pathological angiogenesis is unknown. Here we demonstrate that endothelial α-pv is required for tumour angiogenesis. Using an inducible knockout approach in which the α-pv gene (Parva) was inactivated specifically in endothelial cells of brain tumour-bearing mice, we show that loss of endothelial α-pv results in reduced vessel density and decreased vascular complexity of the pathological neo-vasculature without affecting the structure of the brain vasculature around tumour. Reduced tumour vascularisation is associated with a significant increase in tumour cell apoptosis and a reduction in tumour volume. Together, our data show for the first time that endothelial α-pv is required for tumour vascularisation and tumour progression in vivo.

Cannabidiol converts NF-κB into a tumor suppressor in glioblastoma with defined antioxidative properties.

BACKGROUND: The transcription factor NF-κB drives neoplastic progression of many cancers including primary brain tumors (glioblastoma [GBM]). Precise therapeutic modulation of NF-κB activity can suppress central oncogenic signaling pathways in GBM, but clinically applicable compounds to achieve this goal have remained elusive. METHODS: In a pharmacogenomics study with a panel of transgenic glioma cells, we observed that NF-κB can be converted into a tumor suppressor by the non-psychotropic cannabinoid cannabidiol (CBD). Subsequently, we investigated the anti-tumor effects of CBD, which is used as an anticonvulsive drug (Epidiolex) in pediatric neurology, in a larger set of human primary GBM stem-like cells (hGSC). For this study, we performed pharmacological assays, gene expression profiling, biochemical, and cell-biological experiments. We validated our findings using orthotopic in vivo models and bioinformatics analysis of human GBM datasets. RESULTS: We found that CBD promotes DNA binding of the NF-κB subunit RELA and simultaneously prevents RELA phosphorylation on serine-311, a key residue that permits genetic transactivation. Strikingly, sustained DNA binding by RELA-lacking phospho-serine 311 was found to mediate hGSC cytotoxicity. Widespread sensitivity to CBD was observed in a cohort of hGSC defined by low levels of reactive oxygen species (ROS), while high ROS content in other tumors blocked CBD-induced hGSC death. Consequently, ROS levels served as a predictive biomarker for CBD-sensitive tumors. CONCLUSIONS: This evidence demonstrates how a clinically approved drug can convert NF-κB into a tumor suppressor and suggests a promising repurposing option for GBM therapy.

TAMEP are brain tumor parenchymal cells controlling neoplastic angiogenesis and progression.

Aggressive brain tumors like glioblastoma depend on support by their local environment and subsets of tumor parenchymal cells may promote specific phases of disease progression. We investigated the glioblastoma microenvironment with transgenic lineage-tracing models, intravital imaging, single-cell transcriptomics, immunofluorescence analysis as well as histopathology and characterized a previously unacknowledged population of tumor-associated cells with a myeloid-like expression profile (TAMEP) that transiently appeared during glioblastoma growth. TAMEP of mice and humans were identified with specific markers. Notably, TAMEP did not derive from microglia or peripheral monocytes but were generated by a fraction of CNS-resident, SOX2-positive progenitors. Abrogation of this progenitor cell population, by conditional Sox2-knockout, drastically reduced glioblastoma vascularization and size. Hence, TAMEP emerge as a tumor parenchymal component with a strong impact on glioblastoma progression.

Targeting APLN/APLNR Improves Antiangiogenic Efficiency and Blunts Proinvasive Side Effects of VEGFA/VEGFR2 Blockade in Glioblastoma.

Antiangiogenic therapy of glioblastoma (GBM) with bevacizumab, a VEGFA-blocking antibody, may accelerate tumor cell invasion and induce alternative angiogenic pathways. Here we investigate the roles of the proangiogenic apelin receptor APLNR and its cognate ligand apelin in VEGFA/VEGFR2 antiangiogenic therapy against distinct subtypes of GBM. In proneural GBM, apelin levels were downregulated by VEGFA or VEGFR2 blockade. A central role for apelin/APLNR in controlling GBM vascularization was corroborated in a serial implantation model of the angiogenic switch that occurs in human GBM. Apelin and APLNR are broadly expressed in human GBM, and knockdown or knockout of APLN in orthotopic models of proneural or classical GBM subtypes significantly reduced GBM vascularization compared with controls. However, reduction in apelin expression led to accelerated GBM cell invasion. Analysis of stereotactic GBM biopsies from patients as well as from in vitro and in vivo experiments revealed increased dissemination of APLNR-positive tumor cells when apelin levels were reduced. Application of apelin-F13A, a mutant APLNR ligand, blocked tumor angiogenesis and GBM cell invasion. Furthermore, cotargeting VEGFR2 and APLNR synergistically improved survival of mice bearing proneural GBM. In summary, we show that apelin/APLNR signaling controls GBM angiogenesis and invasion and that both pathologic features are blunted by apelin-F13A. We suggest that apelin-F13A can improve the efficiency and reduce the side effects of established antiangiogenic treatments for distinct GBM subtypes. SIGNIFICANCE: Pharmacologic targeting of the APLNR acts synergistically with established antiangiogenic treatments in glioblastoma and blunts therapy resistance to current strategies for antiangiogenesis.See related commentary by Amoozgar et al., p. 2104.

Neurologic Functional Outcomes of Decompressive Hemicraniectomy Versus Conventional Treatment for Malignant Middle Cerebral Artery Infarction: A Systematic Review and Meta-Analysis.

OBJECTIVE: The aims of this study were to evaluate decompressive hemicraniectomy (DHC) versus conventional treatment (CT) for patients with malignant middle cerebral artery (MCA) infarction and to investigate the impact of age and surgical timing on neurologic function and mortality. METHODS: We searched English and Chinese databases for randomized controlled trials or observational studies published before August 2016. Outcomes included good functional outcome (GFO), mortality, and National Institutes of Health Stroke Scale and Barthel index scores. RESULTS: This meta-analysis included 25 studies (1727 patients). There were statistically significant differences between DHC and CT groups in terms of GFO (P < 0.0001), mortality (P < 0.00001), and National Institutes of Health Stroke Scale and Barthel index scores (P < 0.0001) at different follow-up points. Significant differences were observed between the groups in survival with moderately severe disability (P < 0.00001); no differences were observed in survival with severe disability. In the subgroup analysis, in the DHC group, GFO was less in patients >60 years old (9.65%) versus ≤60 years old (38.94%); more patients >60 years old had moderately severe or severe disability (55.27%) compared with patients ≤60 years old (44.21%). CONCLUSIONS: DHC could significantly improve GFO and reduces mortality of patients of all ages with malignant MCA infarction compared with CT, without increasing the number of patients surviving with severe disability. However, patients in the DHC group more frequently had moderately severe disability. Patients >60 years old with malignant MCA infarction had a higher risk of surviving with moderately severe or severe disability and less GFO.

The Prognosis of Anti-Angiogenesis Treatments Combined with Standard Therapy for Newly Diagnosed Glioblastoma: A Meta-Analysis of Randomized Controlled Trials.

BACKGROUND AND PURPOSE: Although bevacizumab (BV) has been approved as second-line therapy for recurrent glioblastoma (GB), the efficacy and safety of BV for patients with newly diagnosed GB remain unclear. METHODOLOGY/PRINCIPAL FINDINGS: We systematically searched electronic databases (PubMed, EMBASE, OVID, etc.) to identify related studies published from January 1966 and August 2016. Eight randomized controlled trials including a total of 2,185 patients with GB were included. We found that the median progression-free survival (PFS) was higher in the BV group than in the standard therapy (ST) group (pooled hazard ratio, 0.73; 95%CI, 0.62-0.86; P = 0.0001). Compared with ST, BV improved the PFS rate at 6 months (OR 3.33, 95% CI 2.73-4.06, p<0.00001) and 12 months (OR 2.10, 95% CI 1.74-2.54, p<0.00001). There were no significant differences in median overall survival between the BV and ST groups (OR, 1.01; 95%CI, 0.83-1.23; P = 0.95). The BV group had higher survival rates at 6 months (OR, 1.41; 95% CI, 1.09-1.84; P = 0.01) and 12 months (OR, 1.23; 95% CI, 1.02-1.48; P = 0.03), but a low survival rate at the 36-month follow-up (OR, 0.57; 95% CI, 0.32-0.98; P = 0.04). For the incidence of adverse events, three adverse outcomes were found to be significantly different between BV and ST groups, including hypertension (8.37% vs. 1.62%, p<0.000001), proteinuria (7.65% vs. 0%, p<0.001), and fatigue (14.54% vs. 9.01%, p = 0.05). CONCLUSIONS/SIGNIFICANCE: Our study indicates that combination of BV with ST for newly diagnosed GB did not improve the median overall survival but result in longer median PFS, maintaining the quality of life and functional status. However, the long-term use of BV is associated with a higher incidence of adverse events and mortality. STUDY REGISTRATION: This research was registered at PROSPERO. (Registration Number: CRD42016038247).

[Application of intraoperative magnetic resonance imaging and multimodal navigation in surgical resection of glioblastoma].

OBJECTIVE: To evaluate the efficacy of intraoperative magnetic resonance imaging (iMRI) and multimodal navigation in surgical resection of glioblastoma. METHODS: Between February 2009 and July 2010, 76 glioblastoma patients underwent surgical resection guided by iMRI and multimodal navigation. The cohort consisted of 43 male and 33 female patients, with a mean age of 49 years (range: 14-79 years). Rates of gross total resection (GTR) and extent of resection (EoR) were calculated at first and final iMRI scans.Pearson χ(2) test was used to compare the rates of GTR. RESULTS: iMRI and multimodal navigation were successfully implemented in all cases. Rates of GTR were misestimated by neurosurgeons in 24 cases (31.6%), which were confirmed by first iMRI. Total tumor resection were achieved in 20 cases (26.3%) as a result of iMRI scan, increasing the rates of gross total resection from 52.6% to 78.9% (χ(2) = 11.692, P = 0.001). Extent of resection in 28 patients who underwent further tumor resection were increased from 81.5% to 98.1%, leading to the overall extent of resection improved from 92.3% to 98.4%. At 3-month follow-up, 3 cases (3.9%) developed permanent neurologic deficits. The mean clinical follow-up was 15.6 months (range 3.0-45.0 months). The 2-year overall survival rate was 19.7%. The median progression-free survival of gross total resection group was 12 months (95% CI: 10.1-13.9 months), compared with 9 months (95%CI: 7.9-10.1 months) of the subtotal resection group (χ(2) = 4.756, P = 0.029). The overall survival of gross total resection group was 16 months (95% CI: 13.7-18.3 months), compared with 12 months (95% CI: 9.7-14.3 months) of the subtotal resection group (χ(2) = 7.885, P = 0.005). CONCLUSION: Combined with multimodal navigation, iMRI helps maximize surgical resection of glioblastoma, preserving neurological function while increasing progression-free survival and overall survival.