Molecular biological and immunohistochemical analysis of tp53 in human ameloblastomas

Abstract

Ameloblastoma is the most frequent epithelial tumor of the jaws. The spread is locally invasive and it tends to recur. Malignant transformation and occurrence of metastases has been described. Immunohistochemical analysis shows an enhanced expression of P53 protein in ameloblastomas. Mutation of the tp53 tumor suppressor gene was verified in several human tumors. In this study histological sections were analyzed for the expression of P53 protein and the tp53 gene was examined for mutations. Tumor DNA from 29 patients with an ameloblastoma was examined for mutations in exons 5 to 8 of the tp53 tumor suppressor gene using PCR, SSCP,- and sequential analysis. Histological sections of the tumors were analyzed immunohistochemically for an overexpression of P53 protein. Two tp53 mutations (6.9%) in ameloblastomas were verified for the first time. In all 58.6% of the tumors showed an immunoreactivity for P53 protein. There was a statistically significant positive correlation (Fisher's exact test p<0.0148) between an increased number of P53-positive tumor cells and the appearance of recurrence. In the face of the uncertain postoperative behavior of ameloblastomas, the immunohistochemical verification of more than 10% P53-positive tumor cells may give a prognostic indication for a tendency to recurrence.