Overexpression and Mutation of p53 Gene in Epithelial Ovarian Cancer

Lee, S K; Lee, J H

Abstract

We adapted p53 immunohistochemical staining (IHS) for use in the paraffin embedded tissue blocks in 50 patients including 38 epithelial ovarian carcinomas and 12 low malignant potentials (LMP). 20 of these 50 cases, including 17 carcinomas and 3 LMP, were examined by single strand confirmation polymorphism (SSCP) analysis of polymerase chain reaction (PCR) products. Because the exons of 5 to 8 of the p53 gene are frequently the site of mutations in many human tumors, analysis of the p53 gene mutation were focused on these sites. The 39.5% incidence of p53 overexpression observed in ovarian cancer is considerably higher than the 8.3% incidence in LMP (p=0.04). 5 (25%) of the tumors demonstrated a SSCP band shift in exon 5 to 8 of p53 gene, including 3 in exon 5 and 2 in exon 7, and all mutations had immunohistochemically detectable p53 protein. There was no significant relationship between the overexpression and mutation of p53 and clinicopathological parameters except histologic grade. The more undifferentiated the primary tumor, the more frequent p53 overexpression and mutation (p=0.02, p=0.01). Recurrent disease developed in 46.7% of p53 overexpressed cases, but there was no relationship between overall survival and p53 overexpression (p > 0.05). Mutation and overexpression of p53 gene are less frequent in early stage ovarian cancers than in advanced cases, and appears to be implicated in late event of ovarian tumorigenesis.