الفهرس 
Expression of Oct4protein in astrocytic tumours histopathologic and immunohistochemical study
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Abstract
Objective: Gliomas are one of the most fatal diseases. Despite advances in treatment strategies, they remain resistant to therapy and this could be attributed to glioma stem cells (GSCs). Oct4 is a member of the POU transcription factor family. Its expression is restricted to pluripotent stem cells and is downregulated when differentiation starts during embryonic development. It is undetectable in adult normal tissue. It could be detected in astrocytomas. It accounts for maintenance and propagation of tumours. Material and methods: Sixty six paraffin embedded biopsies of astrocytomas were collected including; 12 cases of grade I astrocytoma (8 as pilocytic astrocytoma and 4 as SEGA), 19 cases of grade II astrocytoma (14 as diffuse astrocytoma, 4 as pleomorphic xanthoastrocytoma and 1 as pilomyxoid astrocytoma), 15 cases of grade III astrocytoma (anaplastic astrocytoma) and 20 cases of grade IV astrocytoma (16 as glioblastoma and 4 as gliosarcoma). All the cases were studied immunohistochemically using monoclonal anti-Oct4 protein antibody. Results: Oct4 was expressed in 30 cases; 10 cases showed nuclear expression, 9 cases showed cytoplasmic expression and 11 cases showed both. The higher the grade of astrocytoma, the more was the expression and the percentage of positive tumour cells. The intensity of expression was not related to the grade. Oct4 was not expressed in normal brain tissue. Conclusion: Oct4 is a stem cell marker that is expressed in astrocytomas but not in normal brain tissue. Its expression is higher in high grade astrocytomas