TAU PROTEINAS GLIALTUMORS MARKER:ARETROSPECTIVE STUDY Zaynab S. Abdulghany 1 *, Noora M. Kareem 2 and Imad M. AbdulRahman 3 1 Molecular Biology Department, Iraqi Center for Cancer and Medical Genetics Research, University of Mustansiriyah, Baghdad, Iraq. 2 Pathology and Forensic Medicine Department, Alnahrain College of Medicine, University of Alnahrain, Baghdad, Iraq. 3 Department of Public Health, Al-Imamain Alkadhymain Medical City, Baghdad, Iraq. Abstract Tau is a known protein expressed in brain tissue. It is expressed in different neurological diseases like Huntington’s and Alzheimer and also in different cancer types. Her2 protein is known to be a biomarker and prognostic factor in breast cancer and also expressed in different types of carcinoma like gastric, lung, salivary duct, ovarian and endometrial. To determine tau and Her2 protein expressions in different types of primary brain tumors and to assess the correlation between their expression and the grade of the tumor. 54 paraffin blocks of surgical specimen of different brain tumors had been reviewed, selected and categorized as glial, meningioma and pituitary tumors. Clinical details of all the cases were recorded from Immunohistochemistry department of Neurology Hospital in Baghdad/Iraq. Immunohistochemistry for tau and Her2 proteins were performed along with scoring. twenty men and 34 women were diagnosed and underwent surgery as having brain tumor: 30 cases were glial tissue, 22 cases were meningioma and 2 cases were pituitary. Tau protein distribution was as follows: 12 cases [22%] with 0 score, 24 cases [44%] were scored with + 1, 6 cases (11%) with +2 and 12 cases (22%) with +3 score. While Her2 protein expression was negatively scored in all cases. For the glial tumors a correlation between tau immunoreactivity and the grade of the tumors. This study found that tau protein is expressed in glial tumors and suggested that this protein could be a good biomarker for brain tumor classification and can be used as a confirmatory test for glial tumors diagnosis. Key words : Tau protein, Her2 protein, Glioma, Glial tumors, Brain tumor. Abbreviations: MAPT - microtubule-associated protein tau, Her2/neu - Human epidermal growth factor receptor 2, CNS - central nervous system, WHO- world health organization, FFPE - Formalin-Fixed Paraffin-Embedded, DAPI- 3.32 - diaminobenzidine tetrahydrochloride, H 2 O 2 - Hydrogen peroxide, SPSS - Statistical Package for Social Science, SD - standard deviation, p- probability, FTLD- front temporal lobar degeneration, IHC- immunohistochemistry. HRP- horse reddish peroxidase. According to the WHO classification of brain and CNS tumors in 2016, there are many types of brain tumors including: diffuse astrocytic and oligodendroglial tumors, other astrocytic tumors, ependymal tumors , choroid plexus tumors , tumors of pineal region, embryonal tumors, tumors of cranial and para spinal nerves which include meningioma and schawnomma, and others. Glioma which is the most common primary CNS tumors accounting for 70% of primary brain tumors can be described as a collection of tumors arising from glial cells Schwartzbaum et al., (2006). Glial tumors were divided into two major categories: astrocytic and oligodendroglial. They are histologically, Plant Archives Vol. 19 No. 2, 2019 pp. 4453-4458 e-ISSN:2581-6063 (online), ISSN:0972-5210 Introduction Globally, the incidence of most malignant brain and other central nervous system tumors is found to be low in East Asia, Southeast Asia, and India while the highest incidence have been found in Europe, Canada, the United States and Australia. This significant difference in incidence in Asian populations and European populations indicates the possible influence of origin, genetic and environmental factors in malignant brain tumors. The astrocytic tumors showed the highest distribution globally in all age groups, while medulloblastoma and other embryonal tumors were the lowest Leece et al., (2017). *Author for correspondence : E-mail: dr.nooramk@gmail.com