LOW INCIDENCE OF POINT MUTATION AT CODON 12 OF K-RAS PROTOONCOGENE IN SQUAMOUS-CELL CARCINOMA OF THE UPPER AERODIGESTIVE TRACT

Forty-two cases of squamous cell carcinoma arising in the upper aerodigestive tract were examined to determine the incidence and type of point mutation in codon 12 of the c-K-ras gene by using the polymerase chain reaction and oligonucleotide hybridization techniques on DNA extracted from paraffin blocks. DNA sequencing, in addition, was performed in 4 cases. No point mutation was detected in codon 12 of c-K-ras in the 42 squamous cell carcinomas we examined. According to the results of DNA sequencing of 4 cases, codon 13 also revealed no point mutation. Thus, point mutational activation of codon 12 of c-K-ras oncogene is an uncommon event in human upper aerodigestive tract squamous cell carcinoma.