ABERRANT P53 EXPRESSION IN ASTROCYTIC NEOPLASMS OF THE BRAIN - ASSOCIATION WITH PROLIFERATION

Aberrant expression of the p53 suppressor gene was evaluated in 102 ca ses of astrocytic neoplasms. Immunohistochemical staining with a monoc lonal 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 positi ve. p53 expression was significantly associated with proliferation rat e 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 gro up (n = 44), p53-positive tumors bad higher proliferation indices, sug gesting that histologically similar tumors could be divided into progn ostically different subgroups by immunohistochemical demonstration of aberrant p53 expression.