p53 protein overexpression in astrocytic neoplasms

Abnormalities of the p53 gene are the most common molecular change in human cancer. In the central nervous system, mutant p53 gene is frequently identified in the tumors with astrocytic differentiation. To investigate the relation between histologic subtypes and p53 protein overexpression, we examined 81 cases of astrocytic neoplasms (24 benign astrocytoma, 28 anaplastic astrocytoma and 29 glioblastoma multiforme) using the standard immunohistochemical method. All were formalin-fixed and paraffin-embedded tissue. The p53 immunoreactivity was found in 4/24 benign astrocytoma, 18/28 anaplastic astrocytoma, 22/29 glioblastoma multiforme. The degree of immunoreactivity closely correlated with histologic subtypes (p<0.001). Overall p53 protein expression was most frequently detected in glioblastoma multiforme, but strong immunoreactivity (3+) was more frequently found in the anaplastic astrocytoma than in glioblastoma multiforme. Although the frequency of p53 protein expression is low, 4 benign astrocytoma showed distinct nuclear staining. In conclusion the malignant progression of astrocytic neoplasms may be associated with increasing expression of p53 protein.