p53 in Canine Mammary Tumors: From Molecular Pathogenesis to Biomarker Applications and Comparative Oncology.

Canine mammary tumors (CMTs) are common neoplasms in female dogs and serve as an important naturally occurring model for studying human breast cancer. The p53 protein plays an important role in CMT biology, with alterations in the p53 pathway implicated in tumor development, progression, and tumor microenvironment regulation. However, reported frequencies of TP53 mutations and p53 expression vary among CMT studies, and their associations with malignancy are not uniform. Thus, p53 has potential as a biomarker for CMT, although its clinical applicability requires standardized assessment and further validation. Studies examining p53 in combination with other molecular markers, p53-miRNA interactions, and the role of p53 in chemoresistance further highlight its potential diagnostic, prognostic, and therapeutic relevance. This review synthesizes current evidence on TP53/p53 alterations, biological functions, and biomarker applications in CMT, with particular emphasis on evidence heterogeneity, methodological limitations, and species-specific differences relevant to comparative oncology.