Mutation of p53 gene codon 63 in saliva as a molecular marker for oral squamous cell carcinomas

The inactivation of tumor suppressor gene (TSG) is important during multist age carcinogenesis. The p53 TSG is frequently mutated in oral squamous cell carcinomas. These mutations can serve as very specific markers for the pre sence of tumor cells in a background of normal cells. In this study, 10 ora l squamous cell carcinoma patients and 27 normal dental students were colle cted from Chung Shan Medical and Dental College Hospital, Taichung, Taiwan. Extractions of DNA from saliva were obtained. Ex,von 4 and intron 6 within the p53 gene were amplified with polymerase chain reactions (PCRs) followe d by DNA sequence analysis. DNA sequence analysis of PCR products revealed that five of eight (67.5%) tumor saliva samples and five of 27 (18.52%) hea lthy saliva samples contained p53 exon 4 codon 63 mutations. These results were significantly different by using Chi-square test (P < 0.05). Thr major ity of the base substitutions were C deletions. Probable hot spots for the mutation were identified at exon 4 codon 63, which has not been observed be fore in head and neck cancers. Our study indicated that mutation of p53 cod on 63 in saliva might be a molecular marker for oral squamous cell carcinom as. in addition, the amount of DNA recovered from saliva in most cases is s ufficiently large and its quality suitable to enable PCR amplification whic h could be used in the search for mutations. The protocol described is rapi d, cheap, and easy to perform, and may be useful for epidemiological studie s for oral carcinogenesis. (C) 2000 Elsevier Science Ltd. All rights reserv ed.