ANALYSIS OF THE EQUINE TUMOR-SUPPRESSOR GENE P53 IN THE NORMAL HORSE AND IN 8 CUTANEOUS SQUAMOUS-CELL CARCINOMAS

Wild type equine p53 was amplified between exons 2 and 9 by the polyme rase chain reaction using primers designed from conserved regions in o ther species. An 828 base pair region, corresponding to codons 25-313 of human p53, was sequenced in both directions. Human and equine amino acid sequences were 87% homologous in this region and 96% homologous in conserved domains II-V. Of eight equine cutaneous or mucocutaneous squamous cell carcinomas directly sequenced from exons 5-8, two had p5 3 point mutations resulting in single amino acid substitutions.