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

The study investigates the functionality of the p53 gene in horses, both healthy and those with cutaneous squamous cell carcinomas. Results showed a significant level of homology between human and equine amino acid sequences, and evidence of p53 mutations in some instances of the equine cancer.

Research Methodology

• The researchers utilized the polymerase chain reaction (PCR), a method widely used in molecular biology to make multiple copies of a specific DNA segment. This enabled them to amplify the equine p53 between exons 2 and 9.
• Using primers designed from conserved regions in other species, they managed to sequence an 828 base pair region corresponding to codons 25-313 of human p53 in both directions.

Comparison of Human and Equine Sequences

• The comparison of human and equine sequences revealed an 87% homology (similarity in genetic sequences owing to shared ancestry) in the analyzed region, indicating a high degree of evolutionary conservation between the two species.
• The homology rate was even higher in the conserved domains II-V, reaching 96%, which underscores the fundamental nature and importance of these specific domains in the function of the p53 protein.

Equine Cutaneous Squamous Cell Carcinomas Analysis

• The researchers directly sequenced from exons 5-8 eight cases of equine cutaneous or mucocutaneous squamous cell carcinomas, a form of skin cancer particularly common in horses.
• Out of these eight cases, two were found to have point mutations in the p53 gene, leading to single amino acid substitutions. These mutations can alter the function of the p53 protein, often leading to unrestrained cell growth and proliferation, thus contributing to the development of cancer.