Glia-specific antigen in the intracranial tumors. Immunofluorescence study

Identification of mitophagy-related genes impacting patient survival in glioma

BACKGROUND

This study presents a new prognostic model using mitophagy-related genes (MRGs) in glioma, a type of brain tumor, developed through bioinformatics. The model seeks to improve the understanding of glioma prognosis by focusing on mitophagy, a cellular process that eliminates damaged mitochondria and influences tumor behavior and patient outcomes.

METHODS

The expression profile and clinical information of patients were downloaded from TCGA (The Cancer Genome Atlas) and GEO (Gene Expression Omnibus). By analyzing the correlation between the 14 MRGs and glioma prognosis, we established a novel prognostic model in the TCGA training cohort and validated it in the GSE16011 dataset.

RESULTS

Using univariate Cox regression, we identified 26 MRGs that were significantly enriched in various mitophagy-related pathways. After filtering variables using least absolute shrinkage and selection operator (Lasso) regression analysis, 14 MRGs were introduced to construct the predictive model. The survival analysis showed overall survival of patients with the high-risk score was considerably poorer than that with the low-risk score in both the training and validating cohorts (p < 0.01). The risk score was found to be an independent prognostic factor for glioma in both univariate and multivariate Cox regression analyses. Interestingly, Geneset enrichment analysis (GSEA) analysis revealed that multiple signaling pathways related to neurotransmission were significantly enriched in the high-risk group. Additionally, a hub miRNA-mRNA network was established, which disclosed the quantity and classification of miRNAs capable of interacting with 14 MRGs. Finally, our analysis revealed a notable association between 14 MRGs and immune functionality in gliomas.

CONCLUSION

We developed a robust and accurate prognostic model with 14 MRGs. Our findings might provide a reference for the clinical prognosis and management of glioma.

PKA and PKC activation induces opposite glial fibrillary acidic protein (GFAP) expression and morphology changes in a glioblastoma multiform cell line of clonal origin

Possible differentiation mechanisms were investigated in a glioblastoma multiform cell line (GL15) presenting an undifferentiated phenotype with weak glial fibrillary acidic protein (GFAP) and strong vimentin (VIM) expression. Serum-free conditions induced time-dependent increases of GFAP-mRNA and GFAP protein levels, associated with a process-bearing astrocytic morphology. Activation of protein kinase C (PKC) by tumor promoter phorbol 12-myrystate 13-acetate (PMA) induced a rapid morphological differentiation and a decrease in GFAP mRNA, whereas the GFAP level remained unchanged. Such parameters were shown to characterize a physiological differentiation stage in astroglial cultures. Treatment of process-bearing GL15 cells with dibutyryl cyclic AMP (dbcAMP), a protein kinase A (PKA) activator, induced a time-dependent decrease in the GFAP mRNA and GFAP protein levels and reverted morphological changes induced by serum-free conditions. Neither PMA nor dbcAMP influenced the VIM mRNA expression. In GL15 cells, PKC and PKA activation have opposite effects. Understanding the role of these kinases in malignant transformation and in the in vitro differentiation process is of both basic and clinical interest.

Developmental expression of the glial fibrillary acidic protein mRNA in the central nervous system and in cultured astrocytes

The expression of glial fibrillary acidic protein (GFAP)-mRNA during mouse brain development and in astroglial primary cultures has been investigated by using two approaches: Northern-blot evaluation using a specific cDNA probe, and cell-free translation associated with immunoprecipitation. During brain maturation (4-56 days postnatal), the GFAP-mRNA underwent a biphasic evolution. An increase was observed between birth and day 15 (i.e., during the period of astroglial proliferation), which was followed by a decrease until day 56 (i.e., during astroglial cell differentiation). At older stages (300 days), an increase was observed, which might reflect gliosis. During astroglial in vitro development (7-32 days in culture), the GFAP-mRNA showed similar variations. An increase, observed during the period of astroglial proliferation (7-18 days), was followed by a decrease which occurred in parallel to marked changes in cell shape, cell process outgrowth, and the organization and accumulation of gliofilaments. During the same culture period (7-32 days), alpha-tubulin mRNA, which was used as an internal standard, did not vary significantly. These results show that the increase of the GFAP protein and of gliofilaments observed both in vivo and in vitro during astroglial differentiation cannot be ascribed to an accumulation of the GFAP-mRNA. It might be that more than one mechanism regulates the levels of free and polymerized GFAP and of its encoding mRNA.

Immunological and biochemical strategies for the identification of brain tumor-associated antigens

Various strategies have been used to identify and characterize the antigens associated with human brain tumors. These approaches have included the raising of polyclonal and monoclonal antibodies against tumor antigens and, more recently, efforts toward the direct biochemical identification of such proteins. This review summarizes the progress made in this area, suggests reasons for the broad antigenic cross-reactivity and heterogeneity revealed by these studies, and proposes additional methods for deciphering the complex antigenic composition of human brain tumors.

Glial fibrillary acidic protein in tuberous sclerosis

We examined two cases of tuberous sclerosis for the presence of glial fibrillary acidic protein (GFAP) using the immunoperoxidase technique. The majority of abnormal giant cells in the cerebral cortex showed no reaction to anti-GFAP. Some abnormal cells in the cortical tuber and white matter showed a weak positive reaction. All of the subependymal tumor cells showed no GFAP in their cytoplasm. The abnormal giant cells in tuberous sclerosis, morphologically similar to gemistocytic astrocyte, are not accompanied by antigenic properties of GFAP.

Glial fibrillary acidic protein and induced differentiation of glia in vitro

Glial fibrillary acidic protein (GFAP), a protein largely limited to astrocytes, is abundant and uniformly distributed in spindle-shaped human astrocytoma cells in early explants in culture but becomes predominantly perinuclear as the cells assume a "flat" irregular (epithelioid) shape. GFAP moves from the predominantly perinuclear site to the periphery of the cells and into the developing processes of those cells in which differentiation has been induced by serum starvation in minimum essential medium (MEM). This redistribution of GFAP does not occur in a small percentage of cells, specifically those in which low serum concentration fails to induce morphologic differentiation. In Eagle's basal medium (BME), which, combined with serum starvation, fails to induce differentiation, there is no shift of GFAP. Spontaneously differentiated cells in media wtih 10% serum, differ morphologically from cells with induced differentiation; in the former the cell bodies are smaller and the processes better developed and longer. GFAP in the spontaneously differentiated cells is distributed throughout the cytoplasm and the processes and is more abundant than in cells with induced differentiation. The results suggest the following: (1) GFAP redistribution plays a role in glial differentiation and process formation. (2) There are differences between spontaneous and induced differentiation. (3) There is some critical difference between MEM and BME in the induction of differentiation. (4) A heterogeneous expression of GFAP is implied in the variable staining of cells grown from different primary tumors. Also it is hypothesized that GFAP may play an inhibitory role in highly plastic movements of astrocytes but not in extension and retraction movements of processes.

The utilization of native glioma antigens in the assessment of cellular and humoral immune responses in malignant glioma patients

Cellular and humoral components of the immune response have been studied preoperatively, concurrently, and serially in patients with malignant glial neoplasms. In order to assess titres of circulating antibodies to tumour cell constituents an indirect immunofluorescent technique was applied to single cell suspensions and snap frozen cell smears. In an allogeneic system, 49% of 47 test and 7% of 124 control sera gave a positive response to cytoplasmic components. The leucocyte adherence inhibition assay was applied to study 39 test and 64 control patients. Significant non-adherence of leukocytes was observed in 77% of test cases. Control parameters indicated specificity of the response. Simultaneous assessment in 28 test patients yielded a positive response for one or both assays in 89% of cases..

Immunological aspects of intrinsic glial tumors

✓ Fundamental concepts of general tumor immunology and modes of immunotherapy are presented. Significant work dealing with the relationship of the immune system to intrinsic glial neoplasms is reviewed in relation to therapeutic applications and future investigative efforts.

Glial fibrillary acidic protein (GFAP): purification from human fibrillary astrocytoma, development and validation of a radioimmunoassay for GFAP-like immunoactivity

The extraction and purification of glial fibrillary acidic protein (GFAP) from human fibrillary cerebellar astrocytoma is described. Using an immunoperoxidase method, antisera raised to the protein showed specific staining of astrocytes in normal spinal cord and in tumours of astrocytic origin. A double antibody radioimmunoassay for GFAP in tissue extract was developed, the detection limit of the assay being 360 pg. Extracts of tissues other than brain or spinal cord did not cross-react significantly in the assay, neither did purified preparations of myelin basic and S-100 proteins. Levels of GFAP in normal CNS tissue were higest in spinal cord (1370 microgram/g wet weight) but a level of 3050 microgram/g wet weight was detected in a fibrillary astrocytoma.

Glial fibrillary acidic protein in ependymomas and other brain tumors. Distribution, diagnostic criteria, and relation to formation of processes

Glial fibrillary acidic protein (GFAP) was studied in ependymomas by the three-step immunoperoxidase method and compared to results in astrocytomas and normal tissues. An order of reactivity for GFAP is presented. Diagnostic criteria, based on GFAP content, are proposed. In ependymomas GFAP-positive cells give rise to only some of the tumor cells, usually those forming tubules and perivascular arrangements. It is hypothesized that the same GFAP-positive cells may form tubules at their luminal poles and may produce perivascular arrangements at their other poles. The aberrant regulation associated with neoplastic transformation in glia is often, but not always, reflected in increased GFAP content. In both astrocytes and ependymal cells GFAP may have a similar function since in both cells the increase in GFAP appears to be related to the development of fibrillary processes.