Angiogenic Gene Signature Derived from Subtype Specific Cell Models Segregate Proneural and Mesenchymal Glioblastoma

Intertumoral molecular heterogeneity in glioblastoma identifies four major subtypes based on expression of molecular markers. Among them, the two clinically interrelated subtypes, proneural and mesenchymal, are the most aggressive with proneural liable for conversion to mesenchymal upon therapy. Using two patient-derived novel primary cell culture models (MTA10 and KW10), we developed a minimal but unique four-gene signature comprising genes vascular endothelial growth factor A (VEGF-A), vascular endothelial growth factor B (VEGF-B) and angiopoietin 1 (ANG1), angiopoietin 2 (ANG2) that effectively segregated the proneural (MTA10) and mesenchymal (KW10) glioblastoma subtypes. The cell culture preclassified as mesenchymal showed elevated expression of genes VEGF-A, VEGF-B and ANG1, ANG2 as compared to the other cell culture model that mimicked the proneural subtype. The differentially expressed genes in these two cell culture models were confirmed by us using TCGA and Verhaak databases and we refer to it as a minimal multigene signature (MMS). We validated this MMS on human glioblastoma tissue sections with the use of immunohistochemistry on preclassified (YKL-40 high or mesenchymal glioblastoma and OLIG2 high or proneural glioblastoma) tumor samples (n = 30). MMS segregated mesenchymal and proneural subtypes with 83% efficiency using a simple histopathology scoring approach (p = 0.008 for ANG2 and p = 0.01 for ANG1). Furthermore, MMS expression negatively correlated with patient survival. Importantly, MMS staining demonstrated spatiotemporal heterogeneity within each subclass, adding further complexity to subtype identification in glioblastoma. In conclusion, we report a novel and simple sequencing-independent histopathology-based biomarker signature comprising genes VEGF-A, VEGF-B and ANG1, ANG2 for subtyping of proneural and mesenchymal glioblastoma

Resolution of Tonsillar Herniation and Cervical Syringomyelia Following Resection of a Large Petrous Meningioma: Case Report and Review of Literature

We describe a case of a large, petrous meningioma associated with tonsillar herniation and cervical syringomyelia. The patient, a 53-year-old woman, had a 6-month history of a dull, aching pain in the occipital region associated with numbness in the right C2 dermatome and left gaze evoked nystagmus. Magnetic resonance imaging (MRI) revealed a large tumor in the right posterior fossa associated with moderate supratentorial hydrocephalus. Secondary tonsillar herniation and cervical syringomyelia extending from C2 to C6 were also identified. The tumor, later confirmed to be a meningioma originating from the petrous region, was resected completely via a retrosigmoid approach. Postoperative MRI demonstrated total resolution of the tonsillar herniation and cervical syringomyelia. The radiological features, potential pathophysiological mechanisms, and treatment strategies are discussed in relation to the recent literature

Attenuation of Tumor Suppressive Function of FBXO16 Ubiquitin Ligase Activates Wnt Signaling In Glioblastoma

Glioblastoma (GBM) is one of the most aggressive and lethal types of brain tumor. Despite the advancements in conventional or targeted therapies, median survival of GBM patients is less than 12 months. Amongst various signaling pathways aberrantly activated in glioma, active Wnt/β-catenin signaling pathway is one of the crucial oncogenic players. β-catenin, an important mediator of Wnt signaling pathway, gets phosphorylated by GSK3β complex. Phosphorylated β-catenin is specifically recognized by β-Trcp1, a F-box/WD40-repeat protein and with the help of Skp1 it plays a central role in recruiting phosphorylated β-catenin for degradation. In GBM, expression of β-TrCP1 and its affinity for β catenin is reported to be very low. Hence, we investigated whether any other members of the E3 ubiquitin ligase family could be involved in degradation of nuclear β-catenin. We here report that FBXO16, a component of SCF E3 ubiquitin ligase complex, is an interacting protein partner for β-catenin and mediates its degradation. Next, we show that FBXO16 functions as a tumor suppressor in GBM. Under normal growth conditions, FBXO16 proteasomally degrades β-catenin in a GSK-3β independent manner. Specifically, the C-terminal region of FBXO16 targets the nuclear β-catenin for degradation and inhibits TCF4/LEF1 dependent Wnt signaling pathway. The nuclear fraction of β-catenin undergoes K-48 linked poly-ubiquitination in presence of FBXO16. In summary, we show that due to low expression of FBXO16, the β-catenin is not targeted in glioma cells leading to its nuclear accumulation resulting in active Wnt signaling. Activated Wnt signaling potentiates the glioma cells toward a highly proliferative and malignant state

Original Article - Anterior instrumentation for cervical spine tuberculosis: An analysis of surgical experience with 61 cases

OBJECTIVE: To evaluate the efficacy of anterior instrumentation in patients with subaxial and cervicodorsal spinal tuberculosis in reconstruction of the spine, providing pain relief, neurological recovery and prevention of deformity. MATERIALS AND METHODS: The records of 61 consecutive patients, of surgically treated spinal tuberculosis affecting C3 to D2 region, in our neuro and spinal surgery unit over a five-year period were retrospectively reviewed. Patients with involvement of the C3-C6 vertebrae underwent excision of the involved vertebrae and intervertebral discs followed by reconstruction with titanium implants by anterior approach. A transclavicular approach was used for patients with involvement of the C7-D2 vertebrae. A five-drug antituberculous regimen was administered for a period of one year. The follow-up ranged from 24 to 84 months (mean 38 months). Clinical and radiological assessment using flexion and extension radiographs was performed at 24 months for all cases. RESULTS: The neck pain score based on a visual analog scale (1-10) changed from a pre-operative average of 7 to 2 at follow-up after 4 months. Fifty-two patients (85%) had complete relief of pain while 16 patients who had Grade III to IV muscle strength regained complete power. The asymmetric wasting in patients with involvement of the cervicodorsal region did not recover completely. Flexion-extension radiographs at 24 months did not show any evidence of instability or nonunion. CONCLUSIONS: Anterior reconstruction using titanium plates and locking screws for stabilization of the subaxial and cervicodorsal region tuberculosis is a useful adjunct in preventing kyphotic deformity. A satisfactory segmental stability and fusion is achieved by this technique

Tumor suppressive miRNA-34a suppresses cell proliferation and tumor growth of glioma stem cells by targeting Akt and Wnt signaling pathways

MiRNA-34a is considered as a potential prognostic marker for glioma, as studies suggest that its expression negatively correlates with patient survival in grade III and IV glial tumors. Here, we show that expression of miR-34a was decreased in a graded manner in glioma and glioma stem cell-lines as compared to normal brain tissues. Ectopic expression of miR-34a in glioma stem cell-lines HNGC-2 and NSG-K16 decreased the proliferative and migratory potential of these cells, induced cell cycle arrest and caused apoptosis. Notably, the miR-34a glioma cells formed significantly smaller xenografts in immuno-deficient mice as compared with control glioma stem cell-lines. Here, using a bioinformatics approach and various biological assays, we identify Rictor, as a novel target for miR-34a in glioma stem cells. Rictor, a defining component of mTORC2 complex, is involved in cell survival signaling. mTORC2 lays downstream of Akt, and thus is a direct activator of Akt. Our earlier studies have elaborated on role of Rictor in glioma invasion (Das et al., 2011). Here, we demonstrate that miR34a over-expression in glioma stem cells profoundly decreased levels of p-AKT (Ser473), increased GSK-3β levels and targeted for degradation β-catenin, an important mediator of Wnt signaling pathway. This led to diminished levels of the Wnt effectors cyclin D1 and c-myc. Collectively, we show that the tumor suppressive function of miR-34a in glioblastoma is mediated via Rictor, which through its effects on AKT/mTOR pathway and Wnt signaling causes pronounced effects on glioma malignancy