Loss of heterozygosity of p53 gene of oral cancer detected by exfoliative cytology

The p53 tumor suppressor gene is a 16-20-kb section of cellular DNA located on the short arm of human chromosome 17 at position 17 +/- 13.1. Allelic d eletions and/or point mutations in p53 gene are now known to be associated with the development of carcinogenesis. A hallmark of p53 is that both alle les are generally altered during transformation, which usually represents a loss of heterozygosity (LOH). In this study 30 normal dental students and 22 oral cancer patients were collected from the affiliated hospital of Chun g Shan Medical and Dental College, Taichung, Taiwan. Extractions of DNA fro m the buccal mucosa or cancer surface were sampled by cytology brush. The t wo polymorphic restriction sites exon 4 and intron 6 within the p53 gene we re amplified with polymerase chain reactions followed by restriction fragme nt length polymorphism assay. In heterozygous individuals, 66% of oral canc ers demonstrated lass of p53 gene heterozygosity at the exon 4 site, and 50 % showed LOH at the intron 6 site. These results indicate that inactivation of p53 gene is associated with development and/or progression of oral canc er. The essential advantages of oral exfoliative cytology are the non-invas iveness, painlessness, rapidity, ease and cost-effectiveness of cell sampli ng and DNA extraction. Furthermore, this experimental assay might be useful for preliminary screening of carcinogenesis in human beings. (C) 1999 Else vier Science Ltd, All rights reserved.