Aberrant p53 expression in astrocytic neoplasms of the brain: association with proliferation

Aberrant expression of the p53 suppressor gene was evaluated in 102 cases of astrocytic neoplasms. Immunohistochemical staining with a monoclonal antibody (DO-7) and a polyclonal antibody (CM-1) to p53 protein (both wild type and mutant) on formalin-fixed paraffin sections showed a strong correlation with malignancy grade. The staining was positive in 49% of malignant neoplasms (grades III and IV) and in 19 to 29% of grade II astrocytomas, whereas none of the grade I tumors were positive. p53 expression was significantly associated with proliferation rate determined by immunohistochemical proliferating cell nuclear antigen (PCNA)-staining (median PCNA-labeling index (%): 4.22 (DO-7-positive) versus 1.18 (DO-7-negative), P < 0.0001; 4.02 (CM-1-positive) versus 1.18 (CM-1-negative), P < 0.001). Interestingly, in the glioblastoma group (n = 44), p53-positive tumors had higher proliferation indices, suggesting that histologically similar tumors could be divided into prognostically different subgroups by immunohistochemical demonstration of aberrant p53 expression.