A Study of the Relationship between p53 Mutation and Proliferating Activities in Astrocytic Tumors

Lee, Geun Ho; Choi, Jong Sang

Abstract

To evaluate the relationship between p53 protein expression and proliferating activity in astrocytic tumors, we performed a study using 37 cases of astrocytic tumors; 13 cases of low-grade astrocytoma (LGA), 9 cases of anaplastic astrocytoma (ANA), and 15 cases of glioblastoma multiforme (GM). The p53 protein expression was studied by immunohistochemical staining (IHC) with DO-7 monoclonal antibody in 37 cases and p53 mutation was detected by single strand conformational polymorphism (SSCP) using PCR products of 31 cases. Proliferating activities were detected by Ki-67 (MIB-1) and proliferating cell nuclear antigen (PCNA). Immunohistochemically, 24.3% (9/37) of astrocytic neoplasms showed p53 expression, which consisted of 7.7% (1/13) of LGA, 44.4% (4/9) of ANA, and 26.7% (4/15) of GM. The p53 expression was statistically significant between the tumor grades. p53 mutations on exon 5 were noted in 6 (19.4%) out of 31 cases of astrocytic tumors. Average indices of MIB-1 and PCNA were 1.5 2.6% and 7.0 10.1% in LGA, 10.0 12.7% and 23.7 23.2% in ANA, and 30.9 22.4% and 69.9 26.7% in GM, respectively. p53 positive group by IHC showed significantly higher average MIB-1 (26.2 23.5%) and PCNA index (56.7 30.3%) than those (12.1 18.3%, 27.6 29.6%) of p53 negative group (p<0.05). p53 mutation group also showed significantly higher MIB-1 (30.7 26.0%) and PCNA index (55.5 32.6%) than those without p53 mutation (10.8 16.5%, 24.2 28.7% respectively). These results showed that about one-fifth of astrocytic tumors have p53 abnormalities, which were related with higher proliferating activities than those without p53 abnormalities.