Immunohistochemical evaluation of P53 exprssion in astrocytomas

ABSTRACT

Alteration of the P53 tumor suppressor gene is implicated in tumorigenesis and in progression of a wide variety of human cancers, including gliomas. Accumulation of P53 protein is used as indicator of alteration in P53 gene. Less is known about P53 expression in reactive non-neoplastic lesions [gliosis]. This work is done to verify, the presence of P53 in astrocytomas through immunohistochemistry as well as correlating its expression with clinicopathological parameters and to detect its role in differentiating gliosis from low grade astrocytomas. Ninety-one astrocyromas and 24 cases of reactive gliosis were retrospectively collected from Pathology Department in Assiut University Hospital and private laboratories. Astrocytomas were classified and graded according to WHO classification [2000] using H and E stained sections from formalin fixed paraffin embedded blocks. P53 was immunohistochemically evaluated in selected 46 cases of astrocytomas and 12 cases of reactive gliosis. Glioblastoma multiforme [WHO grade IV] was the predominant grade of astrocytomas. The mean age of patients with asirocytomas showed upregulation with grade. There was male sex predilection in all grades of astrocytomas. P53 protein was detected in 58.7% of astrocytomas including all grades. The immunoreactivity score showed gradual upregulation with increasing grade. There was positive insignificant correlation between P53 expression and age, cellularity and mitosis and positive significant correlation between its expression and pleomorphism, microvascular proliferation and necrosis. All cases of ghosts except one showed negative P53 immunoreactivity. In P53 protein alteration is an early event in lumarigenesis and progression of astrocytomas and is a useful diagnostic tool in diagnosis of high grade gliomas. P53 provides just one more procedure in differentiation of glios is from low grade astrocyromas