LOSS OF HETEROZYGOSITY AND MUTATION ANALYSIS OF THE P16 (9P21) AND P53 (17P13) GENES IN SQUAMOUS-CELL CARCINOMA OF THE HEAD AND NECK

We analyzed allelic loss at the p53 gene (17p13) and at chromosome reg ion 9p21 in 35 primary head and neck squamous cell carcinomas, Loss of heterozygosity (LOH) at p53 and 9p21 was found in 50 and 75% of infor mative cases, respectively, LOH at the p53 gene did not increase signi ficantly with tumor stage, but was more frequent in moderately and poo rly differentiated tumors than in well-differentiated tumors. LOH plus mutation or homozygous deletion of p53 was limited to advanced stage and poorly differentiated tumors, Allelic loss at 9p21 is frequent in early stage head and neck squamous cell carcinoma and is not significa ntly associated with LOH at p53. The second exon of the p16/MTS1/CDKN2 gene was found to be homozygously deleted in 1 of 19 cases showing LO B at 9p21, but direct sequencing did not show mutations in the remaini ng 18 cases. This suggests that p16 plays a limited role in the develo pment of head and neck squamous cell carcinoma.