Arivazhagan Arimappamagan

miR-219-5p Inhibits Receptor Tyrosine Kinase Pathway by Targeting EGFR in Glioblastoma

Glioblastoma is one of the common types of primary brain tumors with a median survival of 12–15 months. The receptor tyrosine kinase (RTK) pathway is known to be deregulated in 88% of the patients with glioblastoma. 45% of GBM patients show amplifications and activating mutations in EGFR gene leading to the upregulation of the pathway. In the present study, we demonstrate that a brain specific miRNA, miR-219-5p, repressed EGFR by directly binding to its 3′-UTR. The expression of miR-219-5p was downregulated in glioblastoma and the overexpression of miR-219-5p in glioma cell lines inhibited the proliferation, anchorage independent growth and migration. In addition, miR-219-5p inhibited MAPK and PI3K pathways in glioma cell lines in concordance with its ability to target EGFR. The inhibitory effect of miR-219-5p on MAPK and PI3K pathways and glioma cell migration could be rescued by the overexpression of wild type EGFR and vIII mutant of EGFR (both lacking 3′-UTR and thus being insensitive to miR-219-5p) suggesting that the inhibitory effects of miR-219-5p were indeed because of its ability to target EGFR. We also found significant negative correlation between miR-219-5p levels and total as well as phosphorylated forms of EGFR in glioblastoma patient samples. This indicated that the downregulation of miR-219-5p in glioblastoma patients contribute to the increased activity of the RTK pathway by the upregulation of EGFR. Thus, we have identified and characterized miR-219-5p as the RTK regulating novel tumor suppressor miRNA in glioblastoma.

A Fourteen Gene GBM Prognostic Signature Identifies Association of Immune Response Pathway and Mesenchymal Subtype with High Risk Group

Background Recent research on glioblastoma (GBM) has focused on deducing gene signatures predicting prognosis. The present study evaluated the mRNA expression of selected genes and correlated with outcome to arrive at a prognostic gene signature. Methods Patients with GBM (n = 123) were prospectively recruited, treated with a uniform protocol and followed up. Expression of 175 genes in GBM tissue was determined using qRT-PCR. A supervised principal component analysis followed by derivation of gene signature was performed. Independent validation of the signature was done using TCGA data. Gene Ontology and KEGG pathway analysis was carried out among patients from TCGA cohort. Results A 14 gene signature was identified that predicted outcome in GBM. A weighted gene (WG) score was found to be an independent predictor of survival in multivariate analysis in the present cohort (HR = 2.507; B = 0.919; p<0.001) and in TCGA cohort. Risk stratification by standardized WG score classified patients into low and high risk predicting survival both in our cohort (p = <0.001) and TCGA cohort (p = 0.001). Pathway analysis using the most differentially regulated genes (n = 76) between the low and high risk groups revealed association of activated inflammatory/immune response pathways and mesenchymal subtype in the high risk group. Conclusion We have identified a 14 gene expression signature that can predict survival in GBM patients. A network analysis revealed activation of inflammatory response pathway specifically in high risk group. These findings may have implications in understanding of gliomagenesis, development of targeted therapies and selection of high risk cancer patients for alternate adjuvant therapies.

A 16-Gene Signature Distinguishes Anaplastic Astrocytoma from Glioblastoma

Anaplastic astrocytoma (AA; Grade III) and glioblastoma (GBM; Grade IV) are diffusely infiltrating tumors and are called malignant astrocytomas. The treatment regimen and prognosis are distinctly different between anaplastic astrocytoma and glioblastoma patients. Although histopathology based current grading system is well accepted and largely reproducible, intratumoral histologic variations often lead to difficulties in classification of malignant astrocytoma samples. In order to obtain a more robust molecular classifier, we analysed RT-qPCR expression data of 175 differentially regulated genes across astrocytoma using Prediction Analysis of Microarrays (PAM) and found the most discriminatory 16-gene expression signature for the classification of anaplastic astrocytoma and glioblastoma. The 16-gene signature obtained in the training set was validated in the test set with diagnostic accuracy of 89%. Additionally, validation of the 16-gene signature in multiple independent cohorts revealed that the signature predicted anaplastic astrocytoma and glioblastoma samples with accuracy rates of 99%, 88%, and 92% in TCGA, GSE1993 and GSE4422 datasets, respectively. The protein-protein interaction network and pathway analysis suggested that the 16-genes of the signature identified epithelial-mesenchymal transition (EMT) pathway as the most differentially regulated pathway in glioblastoma compared to anaplastic astrocytoma. In addition to identifying 16 gene classification signature, we also demonstrated that genes involved in epithelial-mesenchymal transition may play an important role in distinguishing glioblastoma from anaplastic astrocytoma.

STAT-1 expression is regulated by IGFBP-3 in malignant glioma cells and is a strong predictor of poor survival in patients with glioblastoma

OBJECT Insulin-like growth factor binding proteins (IGFBPs) have been implicated in the pathogenesis of glioma. In a previous study the authors demonstrated that IGFBP-3 is a novel glioblastoma biomarker associated with poor survival. Since signal transducer and activator of transcription 1 (STAT-1) has been shown to be regulated by IGFBP-3 during chondrogenesis and is a prosurvival and radioresistant molecule in different tumors, the aim in the present study was to explore the functional significance of IGFBP-3 in malignant glioma cells, to determine if STAT-1 is indeed regulated by IGFBP-3, and to study the potential of STAT-1 as a biomarker in glioblastoma. METHODS The functional significance of IGFBP-3 was investigated using the short hairpin (sh)RNA gene knockdown approach on U251MG cells. STAT-1 regulation by IGFBP-3 was tested on U251MG and U87MG cells by shRNA gene knockdown and exogenous treatment with recombinant IGFBP-3 protein. Subsequently, the expression of STAT-1 was analyzed with real-time reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry (IHC) in glioblastoma and control brain tissues. Survival analyses were done on a uniformly treated prospective cohort of adults with newly diagnosed glioblastoma (136 patients) using Kaplan-Meier and Cox regression models. RESULTS IGFBP-3 knockdown significantly impaired proliferation, motility, migration, and invasive capacity of U251MG cells in vitro (p < 0.005). Exogenous overexpression of IGFBP-3 in U251MG and U87MG cells demonstrated STAT-1 regulation. The mean transcript levels (by real-time RT-PCR) and the mean labeling index of STAT-1 (by IHC) were significantly higher in glioblastoma than in control brain tissues (p = 0.0239 and p < 0.001, respectively). Multivariate survival analysis revealed that STAT-1 protein expression (HR 1.015, p = 0.033, 95% CI 1.001-1.029) along with patient age (HR 1.025, p = 0.005, 95% CI 1.008-1.042) were significant predictors of shorter survival in patients with glioblastoma. CONCLUSIONS IGFBP-3 influences tumor cell proliferation, migration, and invasion and regulates STAT-1 expression in malignant glioma cells. STAT-1 is overexpressed in human glioblastoma tissues and emerges as a novel prognostic biomarker.

Tubercular meningitis with hydrocephalus with HIV co-infection: role of cerebrospinal fluid diversion procedures

OBJECT Hydrocephalus is one of the commonest complications of tubercular meningitis (TBM), and its incidence is increasing with the HIV epidemic. Literature evaluating the role of ventriculoperitoneal shunts in HIV-positive patients with TBM and their long-term prognosis is scarce. METHODS Between June 2002 and October 2012, 30 HIV-positive patients with TBM and hydrocephalus underwent ventriculoperitoneal shunt placement. Thirty age-, sex-, and grade-matched HIV-negative patients with TBM and hydrocephalus were randomly selected as the control group. Outcome was analyzed at discharge (short-term outcome) and at follow-up (long-term outcome). Univariate and multivariate analyses were performed to look for predictors of outcome; p < 0.05 was considered significant. RESULTS There were no differences in the clinical, radiological, or biochemical parameters between the 2 groups. Short-term outcome was better in the HIV-negative group (76.7% improvement) than in the HIV-positive group (70%). However, the long-term outcome in HIV-positive patients was very poor (66.7% mortality and 76.2% poor outcome) compared with HIV-negative patients (30.8% mortality and 34.6% poor outcome). Seropositivity for HIV is an independent predictor of poor outcome both in univariate and multivariate analyses (p = 0.038). However, in contrast to previous reports, of 5 patients with TBM in good Palur grades among the HIV-positive patients, 4 (80%) had good outcome following shunt placement. CONCLUSIONS The authors recommend that shunt treatment should not be performed in HIV-positive patients in poor Palur grade with hydrocephalus. A trial of external ventricular drainage should be undertaken in such patients, and shunt treatment should be performed only if there is any improvement. However, HIV-positive patients in good Palur grades should undergo VP shunt placement, as these patients have better outcomes than previously reported.

Preservation of cognitive and musical abilities of a musician following surgery for chronic drug-resistant temporal lobe epilepsy: a case report.

ABSTRACT Mesial temporal lobe epilepsy (TLE) affects a range of cognitive functions and musical abilities. We report a 16-year-old boy diagnosed with drug-resistant right-medial TLE. He is a professional musician, trained in Carnatic classical music. Clinical, electrophysiological, magnetic resonance imaging (MRI) and positron emission tomography evaluation localized the seizure focus to the right medial temporal lobe. Patient underwent detailed neuropsychological evaluation and functional MRI (fMRI) for musical abilities prior to surgery. He underwent an awake craniotomy and tailored resection of lateral neocortex as well as amygdalohippocampectomy under guidance of cortical stimulation and clinical monitoring. The superior temporal gyrus where activation was revealed on task-based fMRI was preserved. At 16-month follow-up, there was no seizure recurrence and his cognitive functions including musical abilities did not deteriorate with surgery. The task-based fMRI while listening to music revealed bilateral frontotemporal activation. There was evidence of increased left frontotemporal connectivity during the postsurgical period in the resting state fMRI. It is hypothesized that the intact neuropsychological and musical abilities might be as a result of intense musical training from an early age despite the illness leading to functional and neural adaptation of the brain might have contributed to his preserved cognitive functions and musical skills. Intense musical training at a young age perhaps not only honed a range of cognitive functions but also resulted in functionally more efficient cognitive networks despite the surgical resection.

Incidence of deep venous thrombosis in patients undergoing elective neurosurgery – A prospective cohort based study

Introduction: The exact incidence of deep vein thrombosis (DVT) in the Indian neurosurgical patient population is uncertain. This situation is quite different from its well-documented incidence in the Caucasian population.This study aims to analyze the incidence, etiopathogenesis, and risk factors in the development of DVT in Indians. This will enable us to formulate country-specific guidelines for its appropriate and timely prophylaxis. Aims and Objectives: To study the incidence of deep venous thrombosis in patients undergoing elective neurosurgery. Materials and Methods: This was a prospective cohort based study analyzing a total of 273 adult (>18 years) patients who underwent elective neurosurgery during a period of 1 year from November 2013 to December 2014.A preoperative baseline Doppler ultrasonography and coagulation profile was performed, followed by postoperative surveillance Doppler ultrasonography biweekly until discharge. Statistical analysis was performed using chi-square test and Pearsons correlation analysis. Results: A total of 33 patients (12.08%) developed DVT in the postoperative period. Hypertension, frequent alcohol intake, smoking, and obesity were found to be the risk factors (P = 0.001). Significant association was observed between malignant tumors, meningiomas, and DVT (P = 0.001). Intraoperative supine and lateral position for more than 5 h, the severity of postoperative motor deficit, and ambulation delay of more than 2 days were significant risk factors (P = 0.001). Conclusion: Our study, one of the first of its kind, details the incidence and etiopathogenesis of DVT in the Indian neurosurgical population. We recommend an early usage of prophylaxis (mechanical and/or pharmacological) in the perioperative period for the high risk category of patients. We hope that this data can be used for preparing country-specific guidelines for DVT prophylaxis.

Rare Pathologies in the Posterior Third Ventricular Region in Children: Case Series and Review

Tumors of the pineal region in children often belong to 2 categories, namely germ cell tumors and pineal parenchymal tumors. Very rare pathologies have previously been reported in this region. Most of these tumors may be similar radiologically, while their management differs. The present series reports 2 children with pineal region tumors, each one being a rare pathological entity by itself, namely an embryonal tumor with abundant neuropil and true rosettes (ETANTR) and a rosette-forming glioneuronal tumor (RGNT). Very few such cases in each pathology have been reported in the literature for the pediatric age group up to now. Our series consists of 2 children, both presenting with a raised intracranial pressure of short duration. Imaging revealed lesions in the pineal region with similar radiological features. Both ETANTR and RGNT demonstrated mild enhancement. The 2 patients underwent surgical decompression either by Poppens approach (n = 1) or a supracerebellar infratentorial approach (n = 1). The patient with ETANTR was advised radiotherapy, while the child with RGNT was advised a regular follow-up. This series presents some rare pathologies which can occur in the posterior third ventricular region with similar radiological features. Management differs based on the histology of the case.

P53 stratification reveals the prognostic utility of matrix metalloproteinase-9 protein expression in glioblastoma

BACKGROUND Despite the conventional acceptance of the matrix metalloproteinases (MMP)-2 and MMP-9, as markers of invasion in glioblastoma (GBM), there is no large body of evidence supporting their role as prognostic markers. Since the co-expression of MMPs with p53 was noted to be prognostic in other cancers, we evaluated the protein expression of MMP-2 and MMP-9 in GBM and explored their prognostic relevance with respect to p53 expression. MATERIALS AND METHODS Tumor tissues from a uniformly treated cohort of 132 GBM patients were examined for MMP-2, MMP-9, and p53 protein expression by immunohistochemistry (IHC). Survival analyses were performed by Cox-regression and Kaplan-Meier (KM) survival analysis. P53 IHC-based stratification of all GBM cases was performed, and subgroup-specific expression of MMP-2 and MMP-9 was correlated with survival. RESULTS MMP-2 and MMP-9 were expressed in p53 positive as well as p53 negative GBM tumors. MMP-2 and MMP-9 protein expressions had no correlation with prognosis. MMP-9 expression, however, emerged as a strong independent predictor of poor survival in p53 positive GBMs on both Cox-regression analysis (P = 0.036) and KM survival analysis (P = 0.008). Further, even on multivariate analysis, MMP-9 remained strongly associated with poor prognosis (P = 0.010). CONCLUSIONS MMP-9 expression strongly associates with poor prognosis in p53 positive GBMs, but the absence of such correlation in p53 negative GBMs, skews the overall relation of this molecule with prognosis. The study highlights that the dual positivity of MMP-9 and p53 is of prognostic relevance in GBM.

Syringomyelia secondary to cervical spondylosis: Case report and review of literature

Syringomyelia secondary to cervical spondylosis is a rare entity to encounter in clinical practice. We discuss the case of a 53-year-old lady who presented with a syringomyelic syndrome and was found to have cervical spondylosis on imaging. Cine-MRI revealed an obstruction of cerebrospinal fluid (CSF) flow in the cervical spinal subarachnoid space. Decompression of the same led to clinical and radiological improvement. There is a potential causal association between cervical spondylosis and syringomyelia. MRI CSF flow studies may help in deciding the course of treatment in such cases. A subset of patients with cervical spondylosis and concurrent spinal cord signal intensity changes may show reversal of the same following intervention.