Glioma Research Paper

Gliomas represent the most common primary brain tumors. In Egypt, astrocytic tumors are the most common glial tumors (79.4% of all gliomas)[1].Histopathologic diagnosis is important for definitive prognostication and treatment. According to the 2007 WHO classification, astrocytoma is classified into four pathological grades: pilocytic astrocytoma (Grade I), diffuse astrocytoma (Grade II), anaplastic astrocytoma “AA” (Grade III) and glioblastoma multiforme “GBM” (Grade IV) [2].
The tumor cells vigorously invade the surrounding tissue, which renders complete surgical resection difficult and leads to the high incidence of recurrence. Patient clinical history reflects the aggressiveness of his tumor; and in spite of multimodal treatment, the median survival time after diagnosis of GBM does not exceed 12 months [3]. However, some patients with similar grades of astrocytoma
have clear discrepancy in survival. Increasing evidence shows that certain tumor biomarkers are more suitable for prognosis assessment of tumors than the pathological grading system [4].
Identification of the cellular origin of gliomas represents a tool for improving the treatment strategies.
The neural stem cell (NSC) and progenitor cells, in addition to differentiated adult glia, represent a substrate for neoplastic transformation. The progression toward a tumorigenic state may occur through abnormal ‘developmental’ programs [5]. The size and the degree of organization of the NSC in a particular tumor might be an important parameter in detecting the clinical course of disease [6].
Recent research suggests that the tumor biology and the resistance to treatment are closely connected to the existence of cancer stem cells (CSCs). The importance of CSCs for estimating the prognosis of gliomas patients has therefore been widely evaluated using several markers closely related to the presence of these cells [8].
Berger et al [7] have proposed a theory that neural stem cells found in the subventricular zone (SVZ) of the mature brain infiltrate and grow into the area surrounding the SVZ, differentiate into glioma progenitor cells, and then extend into the brain, leading to glioma
formation.
Nestin is an intermediate filament (IF) protein involved in the organization of the cytoskeleton, but it has also been implicated in cell signaling, organogenesis, and cell metabolism. Nestin is expressed abundantly during early embryogenesis in neuroepithelial stem cells but is absent in most cells of the mature CNS [9]. It may be expressed in astrocytes of the adult CNS in response to cellular stress, such as neoplastic transformation. It has been detected in primary CNS tumors but not in carcinoma metastases [10-13].
Since proliferative activity is a reliable method to determine tumor biology, there have been continuous researches to assess such biological markers [14]. Survivin is a member of the inhibitors of apoptosis-family, which promotes survival of tumor cells [15]. It is commonly expressed in embryonic and neoplastic tissues and barely expressed in normal cells [16].There is a limited experience with survivin immunostaining and prognosis in anaplastic astrocytoma, and conflicting data exist in glioblastoma [17,18]. Furthermore, survivin may promote radiation resistance in glioblastoma [19].
The aim of this study was to investigate the expression of nestin in different grades of astrocytoma and to evaluate its possible prognostic role in correlations with other prognostic parameters including the survivin index.