G/C Transition on p53 Gene Alterations in Oral Carcinoma

Objective: p53 gene alterations is frequently in Head and Neck carcinomas and analysis of p53 gene can also provide clues to environmental/exogenous or endogenous etiological processes. Methods:In order to understand p53 gene alteration of oral carcinoma in-situ (CIS) and squamous cell carcinoma (SCC), Subjects were conducted to investigate the p53 gene exon 4-8 in patient with oral CIS and SCC. Twenty-five cases of formalin-fixed paraffin of CIS and 16 cases of SCC after P53 immunohistochemistry, and then subjected to microdissected and PCR amplification and followed by p53 gene direct sequencing. Results: Of all cases found 43% of CIS cases and 69% of SCC had mutation (missense, frame shift, and non sense). Therefore CIS and SCC had common point mutations at codons 196, 248, 282, and 306, which any of them known as ‘hot spots'. The p53 gene point mutations in CIS and SCC were highly transitions than transversions (20/35, 57% vs. 15/35, 43%). Furthermore, the different mutation spectrum with high transitions in C to T mutation was more frequent than in A to G (65% and 35% respectively), and some mutation involving in CpG sites. Conclusions: The high transition in p53 gene alterations of oral CIS and SCC reflect methylation and deamination of cytosine or endogenous process.