Relationships between PTEN gene mutations and prognosis in glioma: a meta-analysis

Molecular Characteristics of Thalamic Gliomas in Adults

The 2016 World Health Organization classification of central nervous system tumor firstly introduces molecular diagnosis to glioma, while the molecular features of adult thalamic gliomas (ATGs) in a relatively large sample have not been reported. We aimed at exploring molecular characteristics in ATGs. The data of 97 and 575 newly diagnosed ATGs and superficial gliomas (SGs) patients were collected, and we performed a comparative analysis of molecular characteristics between them. We analyzed expressions of molecules as follow: H3 K27M, isocitrate dehydrogenase1 (IDH1), Ki-67, O6-Methylguanine-DNA methyltransferase (MGMT) promoter, EGFR, p53, ATRX, GFAP, Oligo2, PTEN, MGMT, and MMP9 by immunohistochemistry. Direct gene sequencing was performed to test the H3 K27M, IDH1, and TERT promoter mutation. The median age at diagnosis of ATGs was 36.0 years, and majority of them were high-grade glioma. We found a significant difference in H3 K27M mutation (P = 0.003), IDH1 mutation (P < 0.001), MGMT promoter methylation (P = 0.005), and Ki67 > 0.1 (P < 0.001) between ATGs and SGs. The statuses of IDH1 (P < 0.001), MGMT promoter (P < 0.001), and Ki67 (P < 0.001) were significantly different between these two groups in lower-grade gliomas. And statuses of IDH1 (P < 0.001), Ki67 (P < 0.001), and EGFR (P = 0.032) were different between these two groups in high-grade gliomas. Only Ki67 > 0.1 was differentially expressed between lower- and high-grade gliomas in ATGs (P = 0.014). The high occurrence of H3 K27M mutation and Ki67 > 0.1, rare occurrence of IDH1 mutation, and MGMT promoter methylation in ATGs suggested that ATGs may be a distinct type of glioma entity.

DETERMINATION OF MOLECULAR GENETIC MARKERS IN PROGNOSIS OF THE EFFECTIVENESS OF TREATMENT OF MALIGNANT INTRACEREBRAL BRAIN TUMORS

Intracerebral malignant brain tumors remain one of the most complex problems of neuro-oncology. Today, promising results of the use of targeted drugs have been received, which determine the important diagnostic and predictive value of molecular genetic markers of glial and metastatic brain tumors. Aim: The study of the prevalence of MGMT (O6-methylguanine-DNA methyltransferase) and PTEN (phosphatase and tensin homologue deleted on chromosome 10) gene expression by real time polymerase chain reaction in tumor tissue of gliomas and brain metastases. Materials and methods: From thirty patients were received tumor material (29 cases of glioma III-IV degree of anaplasia and one case of metastatic brain lesion of adenocarcinoma). The normalized expression of MGMT and PTEN genes was determined by real-time polymerase chain reaction. Results: In all 30 (100 %) patients with tumor fragments, we determined normalized expression of MGMT and PTEN genes. In most cases, 53 % of the observations (16 out of 30 patients) showed a low normalized expression of MGMT gene (<40 c. u.) and a low normalized PTEN expression rate of 73 % (22 out of 30 patients) (<40 c. u.). The average expression level of the MGMT gene in the range from 40 to 100 c. u. (6/20 % of patients) was considered prognostic favourable for the response to temozolomide chemotherapy. Conclusions: The study of MGMT gene expression, a chemotherapy marker for temozolomide, indicates a trend toward correlation between expression levels and therapeutic efficacy. The study of the expression of the PTEN gene, the blocker of the PI3K / AKT signal pathway, indicates a different degree of expression of this enzyme in the tumour samples studied. The predictive value of the indicator for target therapy is appropriate in comparison with the EGFR mutation. Further profound analysis of the results is required with increasing number of sampling and observation period.

IDH1 status is significantly different between high-grade thalamic and superficial gliomas

BACKGROUND

While major progress has been made in diagnosis and treatment of gliomas based on molecules, molecular features of thalamic glioma have rarely been reported till now.

OBJECTIVE

IDH1 mutation is important for prognosis of gliomas and represents a distinctive category of glioma. We intended to survey specific molecular abnormalities in high-grade thalamic gliomas (WHO III-IV).

METHODS

We collected data of 50 and 93 newly diagnosed high-grade thalamic and superficial glioma patients respectively and conducted a comparative analysis of molecular characteristics between them. We analyzed expressions of molecules as follow: IDH1/2, P53, Ki-67, ATRX, PTEN, MMP9 and MGMT by Immunohistochemistry (IHC). Direct gene sequencing was performed to test the IDH1(R 132H) mutation.

RESULTS

We found a significant difference of IDH1 mutation between those high-grade gliomas, with 92% (46/50) of the thalamic tumors and 71% (66/93) of the superficial gliomas showing IDH1 wild-type (p= 0.004). It also showed that IDH1 mutation in superficial glioblastomas 18.6% (13/70) occurred more than thalamic glioblastomas 2.6% (1/39) (p= 0.017). As to high-grade superficial gliomas, there were 26 patients with IDH1 mutation, which contained 7, 13, and 6 high, moderate and low Ki-67 expression gliomas, respectively. The IDH1 wild-type group (62 patients), was composed of 29, 30, and 3 high, moderate and low Ki-67 expression gliomas, respectively. There was a significant distinction between the IDH1 mutation and Ki-67 expressions (p= 0.024). We also noted that the occurrence of low Ki-67 expressions 23.1% (6/26) in IDH1 mutation group was outnumbered than IDH1 wild-type group 4.8% (3/62) (p= 0.018). In addition, we found PTEN negative correlated with MMP9 negative in thalamic high-grade gliomas, whereas no such difference was found in superficial gliomas (p= 0.016).

CONCLUSION

The rare occurrence of IDH1 mutant high-grade thalamic gliomas strongly suggested that the high-grade thalamic glioma is another distinct tumor entity as compared to the high-grade superficial gliomas.

Gene Mutation Profiles in Primary Diffuse Large B Cell Lymphoma of Central Nervous System: Next Generation Sequencing Analyses

The existence of a potential primary central nervous system lymphoma-specific genomic signature that differs from the systemic form of diffuse large B cell lymphoma (DLBCL) has been suggested, but is still controversial. We investigated 19 patients with primary DLBCL of central nervous system (DLBCL CNS) using the TruSeq Amplicon Cancer Panel (TSACP) for 48 cancer-related genes. Next generation sequencing (NGS) analyses have revealed that over 80% of potentially protein-changing mutations were located in eight genes (CTNNB1, PIK3CA, PTEN, ATM, KRAS, PTPN11, TP53 and JAK3), pointing to the potential role of these genes in lymphomagenesis. TP53 was the only gene harboring mutations in all 19 patients. In addition, the presence of mutated TP53 and ATM genes correlated with a higher total number of mutations in other analyzed genes. Furthermore, the presence of mutated ATM correlated with poorer event-free survival (EFS) (p = 0.036). The presence of the mutated SMO gene correlated with earlier disease relapse (p = 0.023), inferior event-free survival (p = 0.011) and overall survival (OS) (p = 0.017), while mutations in the PTEN gene were associated with inferior OS (p = 0.048). Our findings suggest that the TP53 and ATM genes could be involved in the molecular pathophysiology of primary DLBCL CNS, whereas mutations in the PTEN and SMO genes could affect survival regardless of the initial treatment approach.

Pediatric Gliomatosis Cerebri: A Review of 15 Years

Gliomatosis cerebri is a rare glial tumor that carries a poor prognosis. Seen in both adults and children, gliomatosis cerebri appears to differ in these populations as with adult versus pediatric glioblastoma. We present 10 children who either presented to the Weill Cornell Medical College or enrolled in the institution's Gliomatosis Cerebri International Registry alongside a cohort of 89 pediatric patients reported in the literature between 2000 and 2014. Age ranged from 4 months to 21 years, with a male to female ratio of 1.71. Median overall survival for patients in the registry cohort was 17 months (n = 10) and for the historic cohort was 13 months (n = 52). Overall survival was analyzed for the combined cohort and was significantly longer when presenting at age ≥ 10 (20 vs 10 months), for boys (18 vs 11 months), and with low-grade pathology (26.5 vs 12 months) but did not vary significantly by treatment approach.

Transmembrane-4-L-six-family-1, a potential predictor for poor prognosis, overexpressed in human glioma

Transmembrane-4-L-six-family-1 (TM4SF1), a tumor-associated antigen, is expressed in various human epithelial malignancies including breast, ovarian, lung, and colon carcinomas. The aim of the present study was to measure TM4SF1 gene expression in human glioma tissues and to investigate its relationship with patient outcome. We measured TM4SF1 expression in tumor tissue from 72 patients with glioma and in eight control brain tissues by means of quantitative reverse transcription-PCR, western blotting, and immunohistochemistry. The survival data including age, sex, Karnofsky performance scores, epilepsy, size of tumor, extent of resection, pathological grade, and TM4SF1 expression were analyzed using Kaplan-Meier analysis and the multivariate test method (Cox's proportional hazards model). We observed a higher level of TM4SF1 expression in human glioma tissues than in control brain tissues. Furthermore, TM4SF1 expression increased with ascending tumor grade (rs=0.950, P<0.05). Kaplan-Meier analysis with the log-rank test indicated that high TM4SF1 expression had a significant negative impact on overall survival (P<0.001). Moreover, multivariate Cox regression analysis revealed that TM4SF1 was an independent prognostic marker in glioma patients. These findings indicate that (a) TM4SF1 is overexpressed in human gliomas in general and (b) the precise level of expression might predict outcome and could be of clinical value.

Surgical Ventricular Entry is a Key Risk Factor for Leptomeningeal Metastasis of High Grade Gliomas

Leptomeningeal metastasis (LM) of high grade gliomas (HGG) can lead to devastating disease courses. Understanding of risk factors for LM is important to identify patients at risk. We reviewed patient records and magnetic resonance imaging (MRI) of all patients with a first diagnosis of HGG who underwent surgery in our institution between 2008 and 2012. To assess the influence of potential risk factors for LM and the impact of LM on survival multivariate statistics were performed. 239 patients with a diagnosis of HGG and at least 6 months of MRI and clinical follow-up were included. LM occurred in 27 (11%) patients and was symptomatic in 17 (65%). A strong correlation of surgical entry to the ventricle and LM was found (HR: 8.1). Ventricular entry was documented in 137 patients (57%) and LM ensued in 25 (18%) of these. Only two (2%) of 102 patients without ventricular entry developed LM. Median overall survival of patients after diagnosis of LM (239 days) was significantly shorter compared to patients without LM (626 days). LM is a frequent complication in the course of disease of HGG and is associated with poor survival. Surgical entry to the ventricle is a key risk factor for LM.

Association of Telomerase Reverse Transcriptase Promoter Mutations with the Prognosis of Glioma Patients: a Meta-Analysis

Previous studies have found that telomerase reverse transcriptase (TERT) has vital roles in the development of malignant diseases including glioma. The occurrence of TERT promoter mutations in gliomas is frequent. So far, several studies on the association between TERT promoter mutations and prognosis of gliomas had been published, but the conclusion was still not uncertain. The aim of the present meta-analysis was to assess the association between TERT promoter mutations and survival of glioma patients by pooling data from published studies. PubMed, Embase, and Web of Science were searched for articles on the association between TERT promoter mutations and survival of glioma patients until June 30, 2015. Hazard ratios (HR) and the 95% confidence intervals (CIs) were utilized to analyze the prognosis of glioma patients with TERT promoter mutations. Heterogeneity of included studies was assessed using Cochrane's Q test and I (2) method. Eleven studies with a total of 3,444 glioma patients were finally included into the meta-analysis. Nine studies reported the HRs adjusting for other confounding factors. Meta-analysis of total 11 studies suggested that TERT promoter mutations were significantly associated with worse prognosis of patients with gliomas (HR = 2.07, 95% CI = 1.58-2.71, P < 0.00001). Meta-analysis of nine studies with adjusted outcomes suggested that TERT promoter mutations were independently associated with worse prognosis of patients with gliomas (HR = 2.28, 95% CI = 1.72-3.01, P < 0.00001). In conclusion, TERT promoter mutation is a promising biomarker for predicting worse prognosis for patients with gliomas. More prospective well-designed cohort studies are needed to further validate its prognostic role in gliomas.

PIPs in neurological diseases

Phosphoinositide (PIP) lipids regulate many aspects of cell function in the nervous system including receptor signalling, secretion, endocytosis, migration and survival. Levels of PIPs such as PI4P, PI(4,5)P2 and PI(3,4,5)P3 are normally tightly regulated by phosphoinositide kinases and phosphatases. Deregulation of these biochemical pathways leads to lipid imbalances, usually on intracellular endosomal membranes, and these changes have been linked to a number of major neurological diseases including Alzheimer's, Parkinson's, epilepsy, stroke, cancer and a range of rarer inherited disorders including brain overgrowth syndromes, Charcot-Marie-Tooth neuropathies and neurodevelopmental conditions such as Lowe's syndrome. This article analyses recent progress in this area and explains how PIP lipids are involved, to varying degrees, in almost every class of neurological disease. This article is part of a Special Issue entitled Brain Lipids.

Exosome-mediated delivery of the intrinsic C-terminus domain of PTEN protects it from proteasomal degradation and ablates tumorigenesis

PTEN mutation is a frequent feature across a plethora of human cancers, the hot-spot being its C-terminus (PTEN-CT) regulatory domain resulting in a much diminished protein expression. In this study, the presence of C-terminus mutations was confirmed through sequencing of different human tumor samples. The kinase CKII-mediated phosphorylation of PTEN at these sites makes it a loopy structure competing with the E3 ligases for binding to its lipid anchoring C2 domain. Accordingly, it was found that PTEN-CT expressing stable cell lines could inhibit tumorigenesis in syngenic breast tumor models. Therefore, we designed a novel exosome-mediated delivery of the intrinsic PTEN domain, PTEN-CT into different cancer cells and observed reduced proliferation, migration, and colony forming ability. The delivery of exosome containing PTEN-CT to breast tumor mice model was found to result in significant regression in tumor size with the tumor sections showing increased apoptosis. Here, we also report for the first time an active PTEN when its C2 domain is bound by PTEN-CT, probably rendering its anti-tumorigenic activities through the protein phosphatase activity. Therefore, therapeutic interventions that focus on PTEN E3 ligase inhibition through exosome-mediated PTEN-CT delivery can be a probable route in treating cancers with low PTEN expression.