P53 GENE-MUTATIONS IN ORAL CARCINOMAS FROM INDIA

In this study, we analyzed 53 oral squamous-cell carcinomas among Indi ans for the presence of alterations in the tumor-suppressor gene p53 b y PCR-SSCP and sequencing methods. Our results showed that 21% (11/53) of oral carcinomas analyzed carried mutations within the exons 5-8 of the p53 gene. We have identified II single-base pair substitutions co nsisting of 10 mis-sense mutations and one at the splice acceptor site , and one deletion mutation involving 4 consecutive bases. The majorit y of the base substitutions were transitions (5 TA to CG and 5 GC to A T), while only one transversion (TA to GC) was observed. Probable hot- spots for the mutation induction were identified at codons 149 and 274 , which have not been observed before in head-and-neck cancers. The mu tational spectrum might have originated from base alkylations at guani ne and thymine residues, caused by some alkylating agents. The present results are thus consistent with the involvement of tobacco-related n itrosoamines in the etiology of oral squamous-cell carcinoma. (C) 1996 Wiley-Liss, Inc.