Abstract
Background: Decreased p63 protein expression in canine transitional cell carcinoma (TCC) of the urinary bladder is associated with vascular invasion of the tumor, metastasis, and shortened survival. ΔNp63, an isoform of p63, is downregulated in high-grade invasive urothelial carcinoma in humans. However, the clinical significance of ΔNp63 expression in canine urinary bladder tumors is unknown. Therefore, it is important to investigate ΔNp63 expression patterns in TCC, the most common urinary bladder tumor in dogs.
Aim: This study aimed to evaluate the expression and role of ΔNp63 in canine TCC of the urinary bladder.
Methods: ΔNp63 expression was compared between the normal canine urinary bladder, polypoid cystitis, and TCC. The correlation of ΔNp63 expression with histopathological and clinical findings was further evaluated, and its usefulness as a prognostic factor was examined.
Results: We observed that ΔNp63 was highly expressed in the normal urinary bladder and polypoid cystitis in dogs, and its expression levels were low in TCC. Furthermore, low levels of ΔNp63 expression were associated with vascular invasion, metastasis, and shortened survival in dogs with TCC.
Conclusion: These results indicate that ΔNp63 expression could serve as a useful biomarker for invasion, metastasis, and prognosis of canine TCC of the urinary bladder.

Key words: metastasis, ΔNp63, survival, transitional cell carcinoma, urinary bladder