p53 and pRb Expression In Oral Cancer and Precancer Lesions

The tumour suppressor genes, namely p53 and pRb are frequently mutated in many human cancers and are related to altered expression of their protein products namely p53 and pRb. Objectives: To study the expression of p53 and pRb proteins in oral squamous cell carcinoma (OSCC), epithelial dysplasia and epithelial hyperplasia tissues. To correlate p53 and pRb expression with risk habits of betel quid chewing and alcohol consumption. Methods: Twenty cases of OSCC, 20 cases of epithelial dysplasias and 20 cases of epithelial hyperplasia were selected from paraffin-embedded archival tissues of the Oral Pathology department, Faculty of Dentistry, University of Malaya. Five normal tissues were included as comparison. All tissues were cut into 5µm sections and subjected to immunohistochemical peroxidase method using monoclonal p53 (DO7) and pRb antibodies respectively. All stained sections were analyzed by light microscopy and a semiquantitative scoring system was used to evaluate the expression of the respective proteins. Results: Twelve cases out of 20 SCC cases and 9 cases from 20 cases of epithelial dysplasia showed p53 overexpression. Only 1 case of epithelial hyperplasia showed p53 overexpression. All normal tissue showed no p53 expression. In pRb expression, only 7 out of 20 cases of SCC and 5 cases out of 20 cases of epithelial dysplasia showed abnormal pRb expression. Only 1 epithelial hyperplasia and 1normal tissue show abnormal pRb expression. Strong correlation of p53 and pRb expression with risk habit of betel quid chewing or alcohol consumption was not observed. Conclusion: The findings of this study was comparable with other studies which showed progression of p53 and pRb altered expression from precancer to cancer lesions. This study was supported by University of Malaya's grant ( Vot F: F0124/2004B )