High incidence of H-ras oncogene mutations in squamous cell carcinoma of lip vermilion.

Nine specimens of well-differentiated squamous cell carcinoma of the lip vermilion have been analyzed for the presence of H-ras oncogene mutations, using the technique of hybridization with synthetic oligonucleotide probes on in vitro amplified tumour DNA. Five specimens harbored mutations: four in codon 12 and one in codon 13. This high incidence (55%) of mutated H-ras genes suggests that their activation may play an important role in lip tumour development and may be connected to the exposure to chemical and/or physical carcinogens.