Molecular neuropathology of low-grade gliomas and its clinical impact

ATP1B3 may promote glioma proliferation and migration through MAPK/NF-KB signaling pathway

Objective

To investigate the function of ATPase Na+/K+ Transporting Subunit Beta 3 (ATP1B3) in gliomas and the molecular mechanisms associated with them in order to identify a novel target and approach for glioma clinical diagnosis and treatment.

Methods

The Cancer Genome Atlas (TCGA), a public tumor database, and the Chinese Glioma Genome Atlas (CGGA) were used to evaluate the differential expression of ATP1B3 in glioma cells of various grades. Its connection to patient survival and prognosis; The siRNA interference approach instantly reduced the amount of ATP1B3 expression in the glioma cell lines U87MG and U251MG. The knockdown efficiency was assessed by Western Blotting (WB) and RT-qPCR. Following ATP1B3 knockdown, the ability of glioma cells to proliferate, migrate, and invade was identified using the Transwell assay and CCK-8. The proteins that might interact with ATP1B3 were filtered out using the TCGA database and literature analysis. The WB assay was used to determine the expression level of Protein Phosphatase 1 Catalytic Subunit Alpha (PPP1CA) following ATP1B3 deletion, immunoprecipitation was used to determine the direct influence of the two proteins, and immunofluorescence was used to analyze the distribution of ATP1B3 and PPP1CA proteins in glioma cells. Cyclin D1 and vascular endothelial growth factor A(VEGFA) expression alterations following ATP1B3 deletion were identified using the WB assay. Following ATP1B3 knockdown, the WB assay was used to determine the expression levels of p-Raf1, p-MEK 1/2, p-ERK 1/2, p-IκBα, and p-P65 in the MAPK and NF-κB signaling pathway.

Results

Database analysis revealed a negative correlation between the patients' prognosis and the expression level of ATP1B3, and a positive correlation with the malignant degree of the glioma. The mRNA and protein expression levels of ATP1B3 were significantly decreased after knockout, and the proliferation, migration and invasion ability of cells in knockout group were significantly lower than those in control group, with statistical difference. The immunoprecipitation results were negative, and the knockdown group's PPP1CA expression was lower than the control group's. Following ATP1B3 knockdown, Cyclin D1 and VEGFA protein expression levels dropped, and the effects were statistically significant. There was a statistically significant drop in the expression levels of p-Raf1, p-MEK 1/2, p-ERK 1/2, p-IκBα, and p-P65 following ATP1B3 deletion.

Conclusion

In gliomas, ATP1B3 is highly expressed. Glioma cell motility, invasion, and proliferation all decline when ATP1B3 expression is lowered. The downstream protein PPP1CA is indirectly regulated by ATP1B3. By controlling the MAPK and NF-κB signaling pathways, ATP1B3 may have a role in the invasion, migration, and proliferation of glioma cells. As a result, the ATP1B3 gene might be a biological target for treatment and a possible neurotumor diagnostic.

Metabolic Profiling of IDH Mutation and Malignant Progression in Infiltrating Glioma

Infiltrating low grade gliomas (LGGs) are heterogeneous in their behavior and the strategies used for clinical management are highly variable. A key factor in clinical decision-making is that patients with mutations in the isocitrate dehydrogenase 1 and 2 (IDH1/2) oncogenes are more likely to have a favorable outcome and be sensitive to treatment. Because of their relatively long overall median survival, more aggressive treatments are typically reserved for patients that have undergone malignant progression (MP) to an anaplastic glioma or secondary glioblastoma (GBM). In the current study, ex vivo metabolic profiles of image-guided tissue samples obtained from patients with newly diagnosed and recurrent LGG were investigated using proton high-resolution magic angle spinning spectroscopy (¹H HR-MAS). Distinct spectral profiles were observed for lesions with IDH-mutated genotypes, between astrocytoma and oligodendroglioma histologies, as well as for tumors that had undergone MP. Levels of 2-hydroxyglutarate (2HG) were correlated with increased mitotic activity, axonal disruption, vascular neoplasia, and with several brain metabolites including the choline species, glutamate, glutathione, and GABA. The information obtained in this study may be used to develop strategies for in vivo characterization of infiltrative glioma, in order to improve disease stratification and to assist in monitoring response to therapy.

Magnetic resonance analysis of malignant transformation in recurrent glioma

Background

Patients with low-grade glioma (LGG) have a relatively long survival, and a balance is often struck between treating the tumor and impacting quality of life. While lesions may remain stable for many years, they may also undergo malignant transformation (MT) at the time of recurrence and require more aggressive intervention. Here we report on a state-of-the-art multiparametric MRI study of patients with recurrent LGG.

Methods

One hundred and eleven patients previously diagnosed with LGG were scanned at either 1.5 T or 3 T MR at the time of recurrence. Volumetric and intensity parameters were estimated from anatomic, diffusion, perfusion, and metabolic MR data. Direct comparisons of histopathological markers from image-guided tissue samples with metrics derived from the corresponding locations on the in vivo images were made. A bioinformatics approach was applied to visualize and interpret these results, which included imaging heatmaps and network analysis. Multivariate linear-regression modeling was utilized for predicting transformation.

Results

Many advanced imaging parameters were found to be significantly different for patients with tumors that had undergone MT versus those that had not. Imaging metrics calculated at the tissue sample locations highlighted the distinct biological significance of the imaging and the heterogeneity present in recurrent LGG, while multivariate modeling yielded a 76.04% accuracy in predicting MT.

Conclusions

The acquisition and quantitative analysis of such multiparametric MR data may ultimately allow for improved clinical assessment and treatment stratification for patients with recurrent LGG.

Refined brain tumor diagnostics and stratified therapies: the requirement for a multidisciplinary approach

Individualized therapies are popular current concepts in oncology and first steps towards stratified medicine have now been taken in neurooncology through implementation of stratified therapeutic approaches. Knowledge about the molecular basis of brain tumors has expanded greatly in recent years and a few molecular alterations are studied routinely because of their clinical relevance. However, no single targeted agent has yet been fully approved for the treatment of glial brain tumors. In this review, we argue that multidisciplinary and integrated approaches are essential for translational research and the development of new treatments for patients with malignant gliomas, and we present a conceptual framework in which to place the components of such an interdisciplinary approach. We believe that this ambitious goal can be best realized through strong cooperation of brain tumor centers with local hospitals and physicians; such an approach enables close dialogue between expert subspecialty clinicians and local therapists to consider all aspects of this increasingly complex set of diseases.

Magnetic resonance of 2-hydroxyglutarate in IDH1-mutated low-grade gliomas

Recent studies have indicated that a significant survival advantage is conferred to patients with gliomas whose lesions harbor mutations in the genes isocitrate dehydrogenase 1 and 2 (IDH1/2). IDH1/2 mutations result in aberrant enzymatic production of the potential oncometabolite D-2-hydroxyglutarate (2HG). Here, we report on the ex vivo detection of 2HG in IDH1-mutated tissue samples from patients with recurrent low-grade gliomas using the nuclear magnetic resonance technique of proton high-resolution magic angle spinning spectroscopy. Relative 2HG levels from pathologically confirmed mutant IDH1 tissues correlated with levels of other ex vivo metabolites and histopathology parameters associated with increases in mitotic activity, relative tumor content, and cellularity. Ex vivo spectroscopic measurements of choline-containing species and in vivo magnetic resonance measurements of diffusion parameters were also correlated with 2HG levels. These data provide extensive characterization of mutant IDH1 lesions while confirming the potential diagnostic value of 2HG as a surrogate marker of patient survival. Such information may augment the ability of clinicians to monitor therapeutic response and provide criteria for stratifying patients to specific treatment regimens.

Long-term epilepsy-associated tumors

The term long-term epilepsy associated tumor (LEAT) encompasses lesions identified in patients investigated for long histories (often 2 years or more) of drug-resistant epilepsy. They are generally slowly growing, low grade, cortically based tumors, more often arising in younger age groups and in many cases exhibit neuronal in addition to glial differentiation. Gangliogliomas and dysembryoplastic neuroepithelial tumors predominate in this group. LEATs are further united by cyto-architectural changes that may be present in the adjacent cortex which have some similarities to developmental focal cortical dysplasias (FCD); these are now grouped as FCD type IIIb in the updated International League Against Epilepsy (ILAE) classification. In the majority of cases, surgical treatments are beneficial from both perspectives of managing the seizures and the tumor. However, in a minority, seizures may recur, tumors may show regrowth or recurrence, and rarely undergo anaplastic progression. Predicting and identifying tumors likely to behave less favorably are key objectives of the neuropathologist. With immunohistochemistry and modern molecular pathology, it is becoming increasingly possible to refine diagnostic groups. Despite this, some LEATs remain difficult to classify, particularly tumors with "non-specific" or diffuse growth patterns. Modification of LEAT classification is inevitable with the goal of unifying terminological criteria applied between centers for accurate clinico-pathological-molecular correlative data to emerge. Finally, establishing the epileptogenic components of LEAT, either within the lesion or perilesional cortex, will elucidate the cellular mechanisms of epileptogenesis, which in turn will guide optimal surgical management of these lesions.