Abstract
Mammary tumors are among the most common neoplasms in dogs and cats, yet cross-species genomic and proteomic comparisons remain limited. This study aimed to characterize the expression of key oncogenic markers—PTEN, AKT, COX-2, TGF-β1, PCNA, and occludin—in canine and feline mammary tumors and to compare molecular subtypes with human breast cancer. A retrospective cohort of 120 formalin-fixed, paraffin-embedded mammary tumor samples (60 canine, 60 feline) was analyzed using immunohistochemistry and tissue microarray. Expression levels were scored semi-quantitatively and correlated with histopathological grade, lymph node metastasis, and survival. Additionally, targeted gene amplification (Cyclin A) was assessed via quantitative PCR. Results revealed that PTEN loss was more frequent in feline tumors (65% vs. 40%, p=0.01) and associated with shorter survival in both species. COX-2 overexpression was prevalent in canine inflammatory carcinomas (80%) but rare in feline tumors (12%). TGF-β1 expression correlated with epithelial-mesenchymal transition markers (E-cadherin loss, vimentin gain). PCNA labeling index was higher in malignant versus benign lesions (p
Keywords
mammary tumor, canine, feline, comparative oncology, immunohistochemistry, PTEN, COX-2, molecular subtypes