Low-grade glioma: supratentorial astrocytoma, oligodendroglioma, and oligoastrocytoma in adults

FYN as an emerging biological biomarker for prognosis and potential therapeutic target in LGG

OBJECTIVES

This study aimed to explore the expression, clinical significance, and functional mechanism of FYN in lower-grade gliomas (LGG).

METHODS

The mRNA and protein expression of FYN in LGG tissues were detected using databases including OncoLnc, GEPIA, and Human protein atlas (HPA). The UCSC Xena browser, TIMER, STRING and Metascape databases were used to investigate Kaplan-Meier survival curves, correlations between FYN expression and various types of immune cell infiltration, protein interaction network and possible functional mechanism.

RESULTS

FYN expression in LGG, IDH mutation or 1p19q co-deletion subgroup was significantly higher than in corresponding control groups (p < 0.05). Patients with higher FYN expression had longer overall survival (p < 0.05). Male or no 1p19q co-deletion groups with higher FYN expression also had longer overall survival (p < 0.05). FYN expression had close correlation with infiltrating levels of cell purity, CD4+T cells, macrophages, and CD8+T cells (p < 0.05). Protein interaction network result showed correlation among FYN, SH2D1A, LCK, CAV1, SRC, CBL and PTK2. Functional enrichment analysis revealed that FYN and its related genes mainly participated in bacterial invasion of epithelial cells and natural killer cell mediated cytotoxicity. Peptidyl-tyrosine phosphorylation, negative regulation of anoikis, immune effector process, transmembrane receptor protein tyrosine kinase signaling pathway, epidermal growth factor receptor signaling pathway, and negative regulation of protein modification process may be the critical biological process.

CONCLUSIONS

FYN is up-expressed in LGG and related to its good prognosis. It participated in tumor pathophysiological processes and may be a therapeutic target for LGG.

Cyclophilin A contributes to shikonin-induced glioma cell necroptosis and promotion of chromatinolysis

Shikonin induces glioma cell death via necroptosis, a caspase-independent programmed cell death pathway that is chiefly regulated by receptor-interacting serine/threonine protein kinase1 (RIP1) and 3 (RIP3). Chromatinolysis is considered as one of the key events leading to cell death during necroptosis. It is usually accompanied with nuclear translocation of AIF and formation of γ-H2AX. Cyclophilin A (CypA) is reported to participate in the nuclear translocation of AIF during apoptosis. However, it remains unclear whether CypA contributes to necroptosis and regulation of chromatinolysis. In this study, our results revealed for the first time that shikonin promoted time-dependent CypA activation, which contributed to nuclear translocation of AIF and γ-H2AX formation. In vitro studies showed that knockdown of CypA by siRNA or inhibition of CypA by its specific inhibitor, cyclosporine A (CsA), not only significantly mitigated shikonin-induced glioma cell death, but also prevented chromatinolysis. Mechanistically, activated CypA targeted mitochondria and triggered mitochondrial superoxide overproduction, which then promoted AIF translocation from mitochondria into the nucleus by depolarizing the mitochondria and intensified the formation of γ-H2AX by promoting intracellular accumulation of ROS. Additionally, the CypA in the nucleus can form DNA degradation complexes with AIF and γ-H2AX, which also promote the execution of chromatinolysis. Thus, we demonstrate that CypA contributes to shikonin-induced glioma cell necroptosis and promotion of chromatinolysis.

Patient and treatment factors associated with survival among pediatric glioblastoma patients: A Surveillance, Epidemiology, and End Results study

Glioblastoma (GBM) is a rare malignancy in children. The United States Surveillance, Epidemiology, and End Results (SEER) database allows large-scale analyses of clinical characteristics and prognostic features. We used it to study patients aged <20 years with histologically confirmed GBM (2000-2010) and examined the relationship between patient demographics, tumor characteristics, patterns of treatment, and outcomes. The primary outcome was disease-specific survival. 302 subjects were identified, with median age 11 years. Median follow-up was 32 months (95% CI 27-39). 34.4% had gross total resection (GTR). 61% underwent radiation after surgery (17% of subjects <3 years, 67% of those aged 4-19 years). Median survival and 2-year survival rates were 20 months and 46.9%, respectively. In multivariate analyses, age, tumor location, extent of resection, and year of diagnosis were significantly associated with the primary outcome. Compared to those aged 0-4 years, subjects aged 5-9 years and 10-14 years had higher risk of mortality. Infratentorial tumor location (HR 2.0, 95% CI 1.2-3.3, p = 0.007) and subtotal resection (HR 2.04, 95% CI 1.4-3.0, p < 0.001) were associated with increased mortality. Later year of diagnosis was significantly associated with decreased risk of death (HR 0.93, 95% CI 0.9-0.99, p = 0.031). There was no association between sex, race, region, or tumor size and the primary outcome. Repeat analyses examining all-cause mortality identified the same risk factors as for CNS cancer-specific mortality. Younger age, supratentorial location, GTR, and later year of diagnosis were associated with improved survival.

Integration of epidemiology, immunobiology, and translational research for brain tumors

We recently identified a pivotal role for the host type I interferon (IFN) pathway in immunosurveillance against de novo mouse glioma development, especially through the regulation of immature myeloid cells (IMCs) in the glioma microenvironment. The present paper summarizes our published work in a number of areas. We have identified single-nucleotide polymorphisms (SNPs) in human IFN genes that dictate altered prognosis of patients with glioma. One of these SNPs (rs12553612) is located in the promoter of IFNA8 and influences its activity. Conversely, recent epidemiologic data show that chronic use of nonsteroidal anti-inflammatory drugs lowers the risk of glioma. We translated these findings back to our de novo glioma model and found that cyclooxygenase-2 inhibition enhances antiglioma immunosurveillance by reducing glioma-associated IMCs. Taken together, these findings suggest that alterations in myeloid cell function condition the brain for glioma development. Finally, in preliminary work, we have begun applying novel immunotherapeutic approaches to patients with low-grade glioma with the aim of preventing malignant transformation. Future research will hopefully better integrate epidemiological, immunobiological, and translational techniques to develop novel, preventive approaches for malignant gliomas.

Differences in molecular genetics between pediatric and adult malignant astrocytomas: age matters

The microscope - the classical tool for the investigation of cells and tissues - remains the basis for the classification of tumors throughout the body. Nowhere has this been more true than in the grading of astrocytomas. In spite of the fact that our parents warned us not to judge a book by its cover, we have continued to assume that adult and pediatric malignant gliomas that look the same, will have the same mutations, and thus respond to the same therapy. Rapid advances in molecular biology have permitted us the opportunity to go inside the cell and characterize the genetic events that underlie the true molecular heterogeneity of adult and pediatric brain tumors. In this paper, we will discuss some of the important clinical differences between pediatric and adult gliomas, with a focus on the molecular analysis of these different age groups.

Assessment of therapeutic response and treatment planning for brain tumors using metabolic and physiological MRI

MRI is routinely used for diagnosis, treatment planning and assessment of response to therapy for patients with glioma. Gliomas are spatially heterogeneous and infiltrative lesions that are quite variable in terms of their response to therapy. Patients classified as having low-grade histology have a median overall survival of 7 years or more, but need to be monitored carefully to make sure that their tumor does not upgrade to a more malignant phenotype. Patients with the most aggressive grade IV histology have a median overall survival of 12-15 months and often undergo multiple surgeries and adjuvant therapies in an attempt to control their disease. Despite improvements in the spatial resolution and sensitivity of anatomic images, there remain considerable ambiguities in the interpretation of changes in the size of the gadolinium-enhancing lesion on T(1) -weighted images as a measure of treatment response, and in differentiating between treatment effects and infiltrating tumor within the larger T(2) lesion. The planning of focal therapies, such as surgery, radiation and targeted drug delivery, as well as a more reliable assessment of the response to therapy, would benefit considerably from the integration of metabolic and physiological imaging techniques into routine clinical MR examinations. Advanced methods that have been shown to provide valuable data for patients with glioma are diffusion, perfusion and spectroscopic imaging. Multiparametric examinations that include the acquisition of such data are able to assess tumor cellularity, hypoxia, disruption of normal tissue architecture, changes in vascular density and vessel permeability, in addition to the standard measures of changes in the volume of enhancing and nonenhancing anatomic lesions. This is particularly critical for the interpretation of the results of Phase I and Phase II clinical trials of novel therapies, which are increasingly including agents that are designed to have anti-angiogenic and anti-proliferative properties as opposed to having a direct effect on tumor cell viability.

The profile of Th17 subset in glioma

The Th17 cell subset is involved in many autoimmune and infectious pathologies. It is also associated with the tumorigenesis process and poor prognosis of certain tumors. However, its expression and function in glioma cases remain unclear. We measured the percentage of Th17 cells in peripheral blood mononuclear cells (PBMCs) and compared the concentrations of relevant cytokines in the serum of 35 glioma patients and 20 healthy donors. Protein, mRNA, and levels of Th17-relevant cytokines in 24 glioma tissues and 5 cerebral trauma tissues were also assessed. We evaluated whether Th17-relevant cytokines were associated with the clinical stages of glioma. The results showed that there were no significant differences in the volume of Th17 cells in PBMCs and serum concentrations of interferon (IFN)-γ, interleukin (IL)-17, IL-6, IL-23, and TGF-β between glioma patients and healthy donors nor did these differences exist in patients with different clinical stages of glioma. Different expression patterns of Th17-relevant cytokines were observed in glioma tissues when compared to trauma tissues. High mRNA-positive ratios of IL-17 (19/24) and retinoid-related orphan receptor (RORC) (18/24) were observed in glioma tissues, but not in trauma tissues. Positive ratios of transforming growth factor (TGF)-β were higher in trauma tissues and glioma grade II than in glioma grade IV. IL-6, IFN-γ, and IL-1β showed high positive ratios, but showed no significant differences between trauma tissues or grades of glioma. None of the glioma and trauma tissues was positive for IL-23. High positive ratios of IL-17 in glioma tissue were confirmed via analysis of immunohistochemical staining. The results demonstrated that IL-17 and other Th17-relevant cytokines could be expressed in glioma tissues. IL-17 expression, the hallmark of Th17 cell subset, may play an important role in glioma tumorigenesis and progression.

Immunotherapeutic approaches for glioma

The development of effective immunotherapy strategies for glioma requires adequate understanding of the unique immunological microenvironment in the central nervous system (CNS) and CNS tumors. Although the CNS is often considered to be an immunologically privileged site and poses unique challenges for the delivery of effector cells and molecules, recent advances in technology and discoveries in CNS immunology suggest novel mechanisms that may significantly improve the efficacy of immunotherapy against gliomas. In this review, we first summarize recent advances in the CNS and CNS tumor immunology. We address factors that may promote immune escape of gliomas. We also review advances in passive and active immunotherapy strategies for glioma, with an emphasis on lessons learned from recent early-phase clinical trials. We also discuss novel immunotherapy strategies that have been recently tested in non-CNS tumors and show great potential for application to gliomas. Finally, we discuss how each of these promising strategies can be combined to achieve clinical benefit for patients with gliomas.

Subtelomeric analysis of pediatric astrocytoma: subchromosomal instability is a distinctive feature of pleomorphic xanthoastrocytoma

Astrocytic neoplasms are genetically heterogeneous; however a low frequency of genomic changes has been found in juvenile pilocytic astrocytoma (PA) in molecular studies. Concerning pleomorphic xanthoastrocytomas (PXA), recent studies have given heterogeneous results for chromosomal alterations. We studied the subtelomeric regions of 19 primary astrocytoma tumors. Results were near normality for the PA group with relative scarcity of chromosomal imbalances, except for the duplication of 3pter in 4/15 and deletion of 21qter in 5/15 of them. In contrast, a specific profile was observed in the 4 PXA tumoral samples. This involved 3pter, 14qter and 19pter duplication and 4qter, 6qter, 9qter, 13cen, 17pter, 18qter and 21qter deletion. Our results indicate that the chromosomal and genetic aberrations in PXAs differed from those typically associated with the diffusely infiltrating astrocytic and oligodendroglial gliomas. These genetic differences would likely contribute to the more favorable behavior of PXAs and may be helpful for molecular differential diagnosis of pediatric cerebral tumors.

Preoperative estimation of residual volume for WHO grade II glioma resected with intraoperative functional mapping

Despite the lack of class I evidence, it is widely agreed that surgery can improve the functional and vital prognosis for WHO grade II gliomas when the resection is at least subtotal radiologically, that is, leaving less than 10 cm(3) of visible residual tumor. Because these tumors frequently invade functional areas, the preoperative estimation of the probable residual volume remains challenging. This article presents a probabilistic map of postoperative residues, with the aim of predicting before the decision for surgical intervention whether the resection could be subtotal. We selected 65 patients who underwent surgery with intraoperative functional mapping between 1999 and 2004 for a WHO grade II glioma located in a sensorimotor and/or language area. For each case, the postoperative image was normalized on a standard atlas, and the residual tumor was segmented. A probabilistic map of residues was then computed. The fusion between the map and a preoperative image allowed a preoperative estimation of the expected extent of resection. The map enhances the regions where grade II glioma cannot be resected. The success rate for the preoperative classification of partial versus subtotal resection is 82%. Although both its reliability and accuracy have to be improved, this probabilistic map gives preoperatively an objective estimation of the expected extent of resection for grade II glioma resected under intraoperative functional mapping. This rationale will assist in decisions regarding surgical resection and may thus contribute to the elaboration of a therapeutic consensus for WHO grade II glioma.

Low‐Grade Gliomas in Adults

Low-grade gliomas are a heterogeneous group of neoplasms usually encountered in younger patient populations. These tumors represent a unique challenge because most patients will survive a decade or more and may be at a higher risk for treatment-related complications. Clinical observations over the years have identified a subset of low-grade gliomas that tends to manifest more aggressive clinical behavior and require earlier, more aggressive intervention. Clinical and molecular parameters may allow better assessment of prognosis and application of risk-adjusted management strategies that may include resection, radiation, or chemotherapy. Improved methods of long-term cognitive and functional assessment are desperately needed in this patient population.

Diffusely infiltrative low-grade gliomas in adults

Diffusely infiltrating low-grade gliomas (LGGs) include astrocytomas, oligodendrogliomas, and mixed oligoastrocytomas (WHO grade 2). Due to the routine use of magnetic resonance imaging, there is an increasing need to formulate treatment guidelines for patients with LGGs. However, there is little consensus about the optimal treatment strategy for diffusely infiltrative LGGs, and the clinical management of LGGs is one of the most controversial areas in neurooncology. Although the standard of care has not been established, several randomized trials are beginning to provide some answers. Furthermore, laboratory correlative studies are defining subsets of LGG that may identify patients with better prognoses and increased chance of responding to therapy. This article reviews the most recent data regarding the treatment of LGG, emphasizing evidenced based approaches from current clinical trials.

Cytokine gene therapy for malignant glioma

Despite advances in surgical and adjuvant therapy, the prognosis for malignant gliomas remains dismal. Malignant gliomas, like other malignancies, are able to overcome host immune defences through a variety of mechanisms that have become increasingly well-characterised over the past decade. However, this 'immunologically privileged' status of the brain is not absolute. Systemic immunisation with brain-specific antigens can induce immune responses that are manifested in the CNS, such as experimental allergic encephalomyelitis. The efficacy of peripheral immunisation against brain tumours has also been demonstrated in preclinical models. Based on these observations, clinical trials of peripheral immunisations with brain tumour-derived antigens have been initiated. A limitation of this approach is that the immunological environment within brain tumours is suboptimal for functions of antitumour immune effector cells. As a means to overcome this issue, delivery of cytokine genes to the tumour site may reverse the inhibitory immunological environment of the brain tumours and enhance the efficacy of peripheral vaccine-induced immune effector cells. The brain tumour environment may also be rendered more immunologically favourable by the delivery of additional antigen-presenting cells that can provide infiltrating effector cells with secondary activation signals. Indeed, the authors' recent data indicate that the injection of intracranial tumours with dendritic cells secreting interferon-alpha enhances the efficacy of peripheral vaccinations with tumour-specific antigens by cross-priming tumour antigen-specific T cells in the cervical lymph nodes. This review highlights the recent literature on cytokine gene therapy for brain tumours, and proposes the effective use of cytokine gene delivery both at the site of vaccines (i.e., the site of antigen presentation) and within the target brain tumours (i.e., the site where the effector cells exert their antitumour immunity). Successful immunogene therapy for brain tumours requires detailed understanding of cytokine functions and the use of them at the appropriate stages/sites of the immunological milieu.

Identification of consistent novel submegabase deletions in low-grade oligodendrogliomas using array-based comparative genomic hybridization

We have analyzed 18 low-grade gliomas using array comparative genomic hybridization (aCGH) with an average resolution of <500 kb. Because the majority of these tumors showed loss of chromosome arms 1p and 19q, we used custom statistical approaches to define submegabase hemizygous losses throughout the genome that correlated with 19q loss. As a result of this analysis, we have identified a approximately 550-kb region in 11q13 and a approximately 300-kb region in 13q12 that showed hemizygous deletion in virtually all the tumors analyzed regardless of their 1p/19q status. FISH analyses of interphase nuclei from the same tumors used for aCGH analysis confirmed the hemizygous loss. The identification of such specific changes provides a potentially very useful diagnostic marker for this subgroup of low-grade tumors. These regions of the genome define small numbers of candidate genes that are within the deletions. The aCGH analysis also defined the spectrum of gain and loss of genomic regions in low-grade oligodendrogliomas.