Gliomas are a group of brain tumors that originate from different types of glial cells in the central nervous system. The prognosis for glioma is generally poor due to limited possibilities for curative treatment. By using a systems level approach to analyze the glioma proteome with respect to clinical outcome based on genome-wide transcriptomics, 263 genes were found to be associated with prognostic outcome.

As part of the release of the Pathology Atlas, the Human Protein Atlas News will present brief summaries of several cancers included in the atlas, and highlight genes with prognostic association in the different cancer forms. Glioma is the most common type of intracranial tumor and consists of a group of malignant brain tumors that originate from various types of glial cells in the central nervous system. The most common and aggressive form is Grade IV astrocytoma, also called glioblastoma or glioblastoma multiforme. Despite being a relatively rare form of cancer, glioma affects patient's health severely. Prognosis depends on type and aggressivity of the glioma, however, in general it is poor due to limited possibilities for curative treatment. Exposure to high dose of ionizing radiation is the main risk factor for developing glioma. The analysis of prognostic genes in glioma was based on publically available gene expression data and clinical metadata from the Cancer Genome Atlas (TCGA), consisting of 153 patients with different stages of glioma. According to the analysis, 263 genes were associated with prognostic outcome, out of which 195 genes were associated with unfavourable prognosis and 68 genes with favourable prognosis.

Receptor accessory protein 2, encoded by the gene REEP2, is a member of a protein family that enhances receptor expression. REEP2,protein has also been suggested to be necessary for endoplasmic reticulum structure. High expression of the REEP2 gene is shown to be associated with unfavourable prognosis in glioma. Immunohistochemical staining of REEP2 shows a differential cytoplasmic expression pattern in glioma patient samples (Figure 1).

The PHGDH gene encodes phosphoglycerate dehydrogenase, an enzyme involved in L-serine synthesis. Mutations in this gene cause phosphoglycerate dehydrogenase deficiency, clinically characterized by neurological disorders including congenital microcephaly, psychomotor retardation and seizures. High expression of the PHGDH gene is shown to be associated with favourable prognosis in glioma. Immunohistochemical staining of PHGDH shows a differential expression pattern localized mainly to the cytoplasm in glioma patient samples (Figure 2). More information about the Glioma Proteome is available in our Pathology Atlas and in the article published in Science (Uhlen et al. 2017).

References

Histology dictionary - Glioma

Feria Hikmet Noraddin