Analysis of the equine tumor suppressor gene p53 in the normal horse and in eight cutaneous squamous cell carcinomas

Wild type equine p53 was amplified between exons 2 and 9 by the polymerase chain reaction using primers designed from conserved regions in other 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 p53 point mutations resulting in single amino acid substitutions.