Expression of Extracellular Matrix Metalloproteinase (MMP-9), E-Cadherin and Proliferation-associated Antigen Ki-67 and their Reciprocal Correlation in Canine Mammary Adenocarcinomas

Background: The purpose of the present study was to determine the expression of the proteins related to tumour metastatic potential, including matrix metalloproteinase (MMP)-9 and E-cadherin, in correlation with the expression of proliferation-associated antigen (Ki-67) in canine mammary adenocarcinomas. Materials and Methods: Material for the studies was obtained during surgery from 35 dogs of various breeds, aged 7 to 16 years. Neoplastic tumours were verified by a pathologist. The studied proteins were detected by immunohistochemical reactions. The microphotographs of the studied tumours were subjected to computer-assisted image analysis using MultiScaneBase V 14.02 software. Results: Expression of MMP-9 was noted in almost 83% of the tumours, expression of E-cadherin in 77% of tumours, while expression of Ki-67 antigen was detected in fewer than 26% of studied tumours. Conclusion: The positive correlation (r=0.375) between expressions of MMP-9 and Ki-67 and negative correlations between E-cadherin and Ki-67 (r=-0.383) as well as between MMP-9 and E-cadherin (r=-0.45) could suggest that expression and biological significance of the studied markers in mammmary adenocarcinomas in dogs resembles the pattern noted in ductal carcinoma, i.e. in the most frequent histological type of malignant tumour in humans. This may point to suitability of the animal model in studies on mechanism of neoplasia and metastases in humans.