NO EVIDENCE OF MUTATION IN THE HUMAN PTC GENE, RESPONSIBLE FOR NEVOIDBASAL-CELL CARCINOMA SYNDROME, IN HUMAN PRIMARY SQUAMOUS-CELL CARCINOMAS OF THE ESOPHAGUS AND LUNG

The high frequency of loss of heterozygosity that has been observed on the distal region of the long arm of chromosome 9 in squamous cell ca rcinomas of esophagus, lung, uterus, and head and neck indicates the p resence of a tumor suppressor gene(s) in this region. To investigate t he possible role of the PTC gene on chromosome 9q22.3, that was identi fied as the cause of nevoid basal cell carcinoma syndrome, during carc inogenesis in esophagus and lung, we examined 20 esophageal squamous c ell carcinomas and 10 squamous cell carcinomas of the lung for mutatio ns in any coding exon of PTC. Using single-strand conformation polymor phism and direct sequencing, we detected no mutations other than two n on-deleterious polymorphisms. Our results suggest that inactivation of some tumor suppressor gene(s) on 9q other than PTC contributes to the development of squamous cell carcinomas in these tissues.